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a 17-year - old boy presented with severe headache of 2 weeks duration and sudden decrease in vision in both eyes for 10 days , right eye followed by left within 5 days . on examination , right eye had no perception of light and left eye had of counting fingers close to face vision .
pupil was fixed dilated and nonreacting to light in right eye and left eye pupil was normal in size , but had ill - sustained reaction to light .
fundus examination revealed subtle temporal pallor of optic disc in both eyes [ fig . 1 ] .
he had undergone computed tomography of the brain and orbit which revealed a lesion in the spheno - ethmoid sinus which was slightly hyperdense .
bone windows showed erosion of the roof of ethmoidal sinus [ fig . 2 ] .
mri of the brain revealed a lesion in the spheno - ethmoid sinuses and located between the two internal carotid arteries which was hyperintense on t1w images and iso- to hyperintense on t2w images [ fig .
picture of the optic nerve head right ( a ) and left ( b ) preoperative ct scan of the brain and paranasal sinuses coronal section ( a ) with bone cuts ( b ) shows lesion in the spheno - ethmoid sinus which is slightly hyperdense and erosion of bone in the roof of the ethmoidal sinus preoperative mri of the brain t1w ( a and b ) : axial sections showing hyperintense lesion in the spheno - ethmoid sinuses and located between the two internal carotid arteries .
t2w ( c and d ) : axial and coronal sections showing iso- to hyperintense lesion patient was immediately referred to neurosurgeon for surgical intervention , but there was a delay of 2 days by the patient .
when he presented to the neurosurgeon , he had developed right oculomotor nerve paresis in addition to the sixth nerve paresis .
right trans - ethmo - sphenoidal approach and total evacuation of the mucocele under general anesthesia .
one week after surgery , the right eye condition was same , but left eye showed vision improvement to counting fingers at 4 m ; pupil was sluggishly reacting to light .
one month after surgery the right eye showed only abducent nerve paresis , while oculomotor nerve paresis was completely resolved ; pupil showed relative afferent pupillary defect .
left eye showed improvement in vision of 6/6 , n6 , and pupillary reaction was normal . on 2 months follow - up , both eyes had full range of ocular movements [ fig . 4 ] .
postoperative clinical picture of the patient showing full range of ocular movements postoperative ct scan of the brain and paranasal sinuses axial section ( a ) with bone window ( b ) showing complete excision of the lesion
mucoceles are cyst - like lesions lined with respiratory epithelium that most commonly produce bone destruction within the paranasal sinuses . approximately two - thirds of all mucoceles involve the frontal sinuses , and the majority of the remainder involve the ethmoidal sinus .
sphenoidal mucoceles occur rarely and have an incidence of 1% of all paranasal sinus mucoceles .
anterior clinoid mucoceles causing optic neuropathy and cranial nerve palsies are reported in the literature , but sphenoid mucoceles causing both optic neuropathy and ophthalmoplegia are very rare and we could not find any similar report in the literature .
the most common is headache ( frontal or retroorbital ; 70% of patient ) and second is visual disturbance ( 65% of patients ) .
other visual symptoms include diplopia , ocular muscle paresis , exophthalmus , and complete visual loss .
the slow and silent expansion of a mucocele may be unsuspected until bone is eroded and it impinges on adjacent structures .
proposed theories for development of mucocele include chronic infection , allergic sinonasal disease , trauma , previous surgery , and in some cases the cause remains uncertain .
lund and milroy proposed that the obstruction to sinus outflow in combination with superimposed infection caused the release of cytokines from lymphocytes and monocytes .
the cytokine release would stimulate fibroblasts to secrete prostoglandins and collagenases , which in turn could stimulate bone resorption leading to expansion of the mucocele .
a large mucocele produces a classic radiographic appearance of an enlarged distorted sinus with a bony defect representing a breakthrough into the adjacent structures .
the ct features include a homogeneous iso- to hyperdense expansile mass , which completely fills the sinus cavity and surrounding structures .
on contrast administration , there is no increase in the density of mucocele due to its avascular mucoid content .
differential diagnosis includes hypophyseal , tumors , craniopharyngioma , meningioma , chordoma , dysgerminoma , cholesteatoma , and tumors arising from nasopharynx , sinuses , and base of the skull .
surgical treatment options consists of trans - nasal endoscopic , trans - ethmoidal , trans - antral , trans - palatal , and trans - septal .
the degree of improvement in visual acuity after an operation depends on visual acuity before the operation , the mode of development of the mucocele , and the time from onset of the disease until surgery .
have described that if surgery is delayed for more than 610 days after the start of visual loss and if there is optic atrophy , the visual prognosis seems to be poor .
the above presented case had symptoms in the right eye for 15 days and in the left eye for 10 days .
although there was no optic atrophy in the right eye , the vision did not improve .
poor recovery of the right eye could be due to comparative delay in presentation and intervention .
mucoceles , though rare , have to be considered in the differential of visual deterioration .
early surgery of these benign lesions will lead to complete recovery even in patients with poor vision . | sphenoid sinus mucocele comprises only 2% of all paranasal sinus mucoceles . in literature
, there is a case report on sphenoidal mucocele causing bilateral optic neuropathy , with unilateral partial recovery and cranial nerve palsy , but we did not come across any literature with bilateral optic neuropathy and ophthalmoplegia together caused by spheno - ethmoidal mucocele .
we present such a rare case of spheno - ethmoidal mucocele causing bilateral optic neuropathy and unilateral sixth nerve palsy who had postsurgery , unilateral good vision recovery , and complete resolution of sixth nerve palsy . |
neck pain is a common musculoskeletal problem that up to 70% of the world population will experience at some point in their lives .
intramedullary spinal cord metastasis is an exceedingly rare complication of malignancy that affects less than 1% of all patients with cancer .
we report a case of a 61-year - old man who presented to primary care clinic with 1-month history of worsening neck pain with associated neurologic deficits . despite initial conservative management ,
magnetic resonance imaging of the cervical spine showed vasogenic edema of the brain and spinal cord and nodularity at the c4-c5 level .
a computed tomography of the chest showed a dense lesion in the left lower lobe of the lung ; histopathology of the biopsied specimen was consistent with moderately differentiated lung adenocarcinoma .
a high index of suspicion is necessary when chronic neck pain acutely worsens , changes in character , or is accompanied by neurologic deficits .
intramedullary spinal cord metastases are rare complications of systemic cancer that commonly present with neck pain and upper extremity paraesthesias ; early diagnosis and management are necessary to prevent complications such as spinal cord hemisection syndrome or spinal cord transection .
neck pain is a common musculoskeletal problem that up to 70% of the world population will experience at some point in their lives .
chronic neck pain is defined as pain in the posterior cervical region that has been present for at least 3 months . in most cases , no specific cause of neck pain is identified , and pain is managed with modalities including opioid medications and epidural injections .
there are , however , certain situations in which the cause of pain must be investigated .
signs of spinal cord involvement as evidenced by paraesthesias and motor deficits warrant further imaging .
this report discusses a 61-year - old man who presented with acute worsening of his chronic neck pain and was ultimately diagnosed with stage iv moderately differentiated adenocarcinoma of the lung .
a 61-year - old man with a medical history of chronic neck and back pain secondary to a motor vehicle accident presented to the clinic with a 1-month history of worsening neck pain .
the x - ray of the cervical spine showed evidence of degenerative disk disease , and he was prescribed hydrocodone .
one week later , the patient returned with progressive worsening of pain associated with upper extremity weakness , decreased grip strength , numbness , and paraesthesias of bilateral upper extremities .
activities of daily living were reported to be severely limited as the patient was unable to dress or bathe himself without assistance .
social history was significant for a several year history of construction work and negative for tobacco or alcohol use . on examination , temperature was 36c , blood pressure was 140/88 mm hg , and pulse was 75 beats per minute . point tenderness was noted on palpation of the cervical spine , and strength and range of motion testing were limited by severe pain .
magnetic resonance imaging ( mri ) of the cervical spine ordered by the primary care physician showed extensive vasogenic edema of the brain and spinal cord as well as a single nodular lesion at the c4-c5 level ( figure 1 ) .
the patient was subsequently admitted to the hospital and had an mri of the brain , cervical , thoracic , and lumbar spinal cord .
imaging revealed innumerable ring - enhancing lesions throughout both cerebral hemispheres , basal ganglia , and cerebellum concerning for metastases .
there was also evidence of a 6 mm 14 mm 9 mm - enhancing nodule in the right lateral ventral spinal cord at the level of c4-c5 .
no other spinal cord lesions were noted . computed tomography ( ct ) of the chest , abdomen , and pelvis
was ordered , revealing a dense consolidation of the left lower lobe ( figure 2 ) .
other ct findings concerning for metastases included mediastinal and periportal lymphadenopathy , a low - density lesion in the posterior spleen , and a nonspecific small sclerotic lesion of the left iliac bone .
although there was initially concern for an infectious process , blood cultures and infectious workup were negative .
transbronchial biopsy of the lesion confirmed the presence of a moderately differentiated adenocarcinoma of the lung with evidence of lymphovascular invasion . in the setting of wide metastases noted on ct
, the disease was found to be consistent with stage iv adenocarcinoma of the left lung .
t1-weighted sagittal image , single spinal cord lesion at c4-c5 level with extensive surrounding vasogenic edema .
dense consolidation noted in left lower lobe , consistent with lung adenocarcinoma with possible overlying infectious process .
promptly after diagnosis , the patient was started on palliative whole brain radiation therapy and spinal radiation therapy .
the tumor was found to be anaplastic lymphoma kinase ( alk ) gene positive , and the patient was subsequently started on crizotinib , an oral tyrosine kinase inhibitor targeting alk . due to central nervous system ( cns ) involvement , dexamethasone was initiated with plan for a long prednisone taper .
this patient s disease course was complicated by steroid - induced psychosis and acute hypoxic respiratory failure which was believed to be multifactorial .
he was found to have a left - sided pleural effusion for which a thoracentesis was performed .
unfortunately , the patient experienced a prompt reaccumulation of loculated fluid , and his respiratory status continued to decline .
intramedullary spinal cord metastasis ( iscm ) is the rarest form of cns complication of a systemic cancer .
the most common primary malignancy leading to iscm is lung cancer , with 47% of cases originating from primary lung cancers .
the next most common primary malignancies giving rise to iscm are breast cancer , melanoma , and lymphoma .
awareness of spinal cord metastasis as a potential cause of neck pain is important to aid in timely diagnosis and treatment .
symptoms quickly progress over the period of days to weeks , frequently resulting in cord hemisection syndrome ( brown - squard ) or spinal cord transection .
the worse the neurologic deficit is at time of symptom presentation , the worse the patient s prognosis will be .
there are several features that help differentiate neck pain secondary to spinal cord compression from degenerative joint disease ( djd ) .
specifically , metastatic spinal cord compression can occur at any level , whereas djd is rarely seen outside of the cervical or lumbar spine .
furthermore , the pain associated with djd is familiar to the patient and has been present intermittently over the span of years , whereas the pain of iscm is commonly seen as a new pain or acute worsening of pain .
it is important to pay attention to these differentiating signs as once the initial neurologic deficit is seen , it may rapidly progress to paralysis over the period of hours to days .
patients with symptoms concerning for cord compression should undergo immediate mri , preferably within 1 day of symptom onset .
magnetic resonance imaging is the imaging modality of choice in the diagnosis of iscm . in this case , the patient s primary care provider appropriately ordered an mri for the initial workup , leading to the diagnosis of iscm as the initial presentation of lung adenocarcinoma .
magnetic resonance imaging allows for accurate localization and differentiation between different types of spinal cord tumors .
signal intensity of the tumor on t2-weighted images helps to differentiate between neoplastic and nonneoplastic lesions ; more specifically , signal patterns can suggest specific diagnoses within these broad categories .
alternatively , although ct may provide evidence that there is spinal cord enlargement or presence of a tumor , it can not delineate the cause .
metastatic spinal cord compression is an oncologic emergency ; early diagnosis is important to prevent neurologic decline .
the initial treatment of choice is radiation , in addition to glucocorticoids , with the goal of minimizing pain and preserving or restoring neurologic function .
indications for neurosurgical intervention are failed radiotherapy , radioresistant tumor types , or rapidly evolving neurologic symptoms .
a high index of suspicion is necessary when chronic neck pain acutely worsens , changes in character , or is accompanied by neurologic deficits .
intramedullary spinal cord metastases are rare complications of systemic cancer that commonly present with neck pain and upper extremity paraesthesias ; early diagnosis and management are necessary to prevent complications such as spinal cord hemisection syndrome or spinal cord transection . | introduction : neck pain is a common musculoskeletal problem that up to 70% of the world population will experience at some point in their lives .
intramedullary spinal cord metastasis is an exceedingly rare complication of malignancy that affects less than 1% of all patients with cancer.case report : we report a case of a 61-year - old man who presented to primary care clinic with 1-month history of worsening neck pain with associated neurologic deficits . despite initial conservative management ,
the patient continued to have progressive worsening of sensory and motor deficits .
magnetic resonance imaging of the cervical spine showed vasogenic edema of the brain and spinal cord and nodularity at the c4-c5 level .
a computed tomography of the chest showed a dense lesion in the left lower lobe of the lung ; histopathology of the biopsied specimen was consistent with moderately differentiated lung adenocarcinoma.conclusions:a high index of suspicion is necessary when chronic neck pain acutely worsens , changes in character , or is accompanied by neurologic deficits .
these clinical signs warrant further investigation into a secondary cause of neck pain .
intramedullary spinal cord metastases are rare complications of systemic cancer that commonly present with neck pain and upper extremity paraesthesias ; early diagnosis and management are necessary to prevent complications such as spinal cord hemisection syndrome or spinal cord transection . |
chronic venous insufficiency ( cvi ) is characterised by the retrograde flow of blood in the
lower extremity .
cvi and its sequel of varicose veins and venous hypertension are among the
most common disorders that affect daily life1 .
the annual incidence of cvi is 26% and 1.9% in women and men , respectively2 .
the main risk factors for cvi include family history , prolonged standing , history of deep
venous thrombosis , age , obesity , and pregnancy2 .
the venous hypertension of cvi usually begins with oedema and
varicose veins and progresses to stasis cellulitis and pigmentation of skin leading into
lipodermatosclerosis and ulceration3 .
since established venous insufficiency can not be cured by pharmacological interventions
alone , it is most commonly treated by non - invasive methods4 , 5 .
the compression therapy
relieves cvi symptoms by improving venous function and hence is preferred among other
physical therapies to treat venous and lymphatic insufficiency of lower limbs .
the
compression stockings ( cs ) and calf muscle pump exercises increase venous return and are
mainstay of conservative treatment4 , 6,7,8 .
ct exerts the highest compression at the ankle which gradually decreases towards knee ,
thereby ensuring the upward flow of blood in the direction of heart and preventing reflux
towards foot or in lateral superficial veins .
the compression pressure gradient of cs , by
reducing diameter of major veins , increases velocity and volume of blood flow and decreases
the venous hypertension and symptoms9 , 10 .
cvi considerably affects patient s health - related quality of life ( hrqol ) . in many
patients ,
the pain and discomfort of cvi affects physical mobility , working capacity and
social life11 .
the international society
for vascular surgery recommended to expand outcome measures for venous disease studies to
include patient - reported measures of functioning and hrqol .
it noted that comprehensive
evaluation of venous disease should include assessment of clinical outcomes and hrqol12 . for chronic conditions like cvi
, the
assessment of hrqol can provide important information on disease burden that may not be
adequately captured with traditional physician - based measures of morbidity or mortality13 .
due to chronic nature of cvi , the long term usage of the cs may be rough considering the
compliance of the patient .
therefore , the present study was aimed to analyse the effect of
short term use of cs on symptoms of cvi and hrqol in cvi patients .
the patients visiting outpatient clinic , at department of cardiovascular surgery , abant
izzet baysal university hospital bolu , turkey were enrolled in this study .
the study was
approved by the clinical research ethics committee of abant izzet baysal university faculty
of medicine ( ib.30.2.ab.0.20.05.04050.01.0460 ) .
inclusion criteria were patients without prior treatment for cvi or varicose vein surgery
and for those the disease was categorised as c2 and c3 according to ceap classification .
exclusion criteria included presence of deep vein thrombosis , congestive heart failure ,
malignancy , patients having more advanced skin changes such as lipodermatosclerosis skin
ulcers or other dermatological disease with pruritus , and patients who had ongoing use of
cs .
all patients enrolled were given detailed explanation of the study following which informed
consent was obtained from them . a questionnaire including demographic information ,
occupational details , and relevant medical history
the generic ,
disease specific hrqol , and depression - related questionnaire was requested from 126
patients .
the turkish version of nottingham health profile ( nhp ) was used to measure a generic hrqol .
it contains 38 questions with assigned individual score from six different categories such
as energy level ( el ; n=3 ) , pain ( p ; n=8 ) , emotional reaction ( er ; n=8 ) , sleep ( s ; n=5 ) ,
social isolation ( si ; n=5 ) , and physical abilities ( pa ; n=8 ) .
for calculation of final score in each category , variation in number
of items per category was rationalised by computing percentage score ( i.e. , each sum was
multiplied by 100 and divided by the number of items in the category ) .
possible scores
ranged from 0 ( indicating all no answers in that category or absence of distress ) to 100
( all yes answers indicating maximal distress ) .
the questionnaire on 26 items from 2 categories of veines - qol / sym measured severity of
symptoms of cvi and its impact on hrqol from patient s perspective .
the five different
frequencies ( always , a few times a week , once a week , once in a few weeks , and never ) for
symptoms fullness of lower extremities , pain , swelling , night cramps , heat / burning
sensation , restless legs , itching , tingling / stinging sensation , and throbbing under 10
different items were assessed .
limitations in daily activities ( 9 items ) , greatest intensity
during the day ( 1 item ) , change over the past year ( 1 item ) , and psychological impact ( 5
items ) were covered by the hrqol scale of 2 to 7 points for response on intensity ,
frequency , or agreement .
the highest score indicated better outcomes in
veines - qol and on veines - sym scale .
veines - qol / sym ; turkish validity and reliability were
established by study of kutlu et al15 .
the beck depression inventory ( bdi ) consists of 21 items ; it is a self - report rating
inventory that measures characteristic of attitude and symptoms of depression .
the study group included
44 patients who regularly used cs and remaining 82 patients who did not use cs were included
in control group .
the class 2 cs ( jobst brand ) of
height below knee and pressure gradient of 2332 mmhg were used .
the patients were asked to
wear cs as soon as they wake up in the morning and take it off before going to bed .
they
were asked to use cs for a period of four weeks , exercise regularly and apply skin care
moisturiser ( ph 5.5 ) .
the exercises prescribed were ankle pumping and heel lifts ( 3 sets of
10 repeats ) and daily walk of 3045 minutes .
the patients were warned that they should not
wear cs while sleeping due to high resting pressure .
the patients ( without use of cs ) in the control group were also prescribed same exercises
and skin care .
all assessments were repeated after a four - week treatment . the statistical program for social sciences ( spss 18.0 , spss inc . ,
quantitative data were presented as mean and standard
deviation and qualitative data as percentage ( % ) and frequency ( n ) .
an independent t - test
was used to compare the differences in venous symptoms , depression and hrqol scores between
groups .
of the 203 patients with cvi interviewed for this study , 77 were excluded due to habitants
of town or village ( n=33 ) , absence of inclusion criteria ( n=27 ) , and rejection to
participate into study ( n=17 ) .
the remaining 126 patients were enrolled into the study :
study group ( n=44 ) and control group ( n=82 ) .
nine patients ( 2 from study group and 7 from
control group ) did not undergo last evaluation .
thus , the study was completed with 117
patients ( 73 females and 44 males ) : study group ( n=42 ) and control group ( n=75 ) .
the average
age of patients was 60.9 9.4 years in study group and 63.1 4.9 years for patients in
control group .
the height ( cm ) , bodyweight ( kg ) and body mass index ( bmi ) ( kg / m ) for
patients in both groups were comparable ( table
1table 1.demographic and clinical features of the patientsstudy groupn=42x sdcontrol groupn=75x sdage ( years)60.9 9.4 63.1 4.9*height ( m)1.63 0.51.63 0.0weight ( kg)81.1 11.679.8 9.5bmi ( kg / m)30.2
values are mean sd , * p<0.05 there were significant differences between groups for veines / sym sub - parameters , nhp , bdi ,
veines - qol and veines / sym total scores before and after receiving treatment ( p<0.001 )
( table 2table 2.comparison of differences for veines - qol , nhp and bdi measurements of the
patients between groups ( n=117)study groupn=42x sdcontrol groupn=75x sdveines
18.2*bdi3.8 8.2 1.3 1.6**values are mean sd , * p<0.05 ) . furthermore , pre- and post - treatment total score differences for each group
were evaluated and maximum differences were found in study group for the scores of nhp , bdi ,
veines - qol , and veines / sym ( table 3table 3.comparison of pre and post treatment scores for groups ( n=75)pre treatmentpost treatmentx sdx sdveines / symstudy group22.4 7.528.5 9.7*control group29.2 10.127.6 9.8*veines - qolstudy group67.8 13.376.7 15.5*control group76.8 16.773.3 16.0*nhpstudy group213.8 157.1166.1 124.2*control group182.0 118.6198.0 120.5*bdistudy group11.0 8.57.1 7.7*control group12.1
* values are mean sd , * p<0.05 * values are mean sd , * p<0.05
the present study showed that short - term use of cs in cvi patients has decreased symptoms
and significantly improved quality of life in these patients .
the compression treatment for venous insufficiency in lower extremity has been used for
hundreds of years since hippocrates . the compression treatment that applies
the reduction in venous reflux due to application of compression below knee is well
known19 . in 112 cvi patients , the use
of cs ( pressure 3040 mmhg ) for one month significantly improved lower extremity pain ,
oedema , activity tolerance , depression , sleep disorders and qol9 . in this study , cs of below knee length
was preferred due to
its comfort , improvement in cs calf muscle pump , and low cost .
cs decreases venous symptoms such as pain , oedema , stasis , and skin changes20 .
the venous symptoms were improved by the
use of class 2 ( 3040 mmhg ) and class 3 ( 4050 mmhg ) cs for six weeks21 .
similarly , a significant decrease in symptom severity
( pain , depression , swelling , sleep ) and increase in activity tolerances were observed in cvi
patients after use of cs for one month9 .
the use of cs improved pain and symptoms in 90% patients with cvi22 . in line with this ,
the decrease in venous symptom scores
suggests importance of short - term cs usage .
the difficulty in wearing cs , financial burden , discomfort of heat and tightness of
stocking are responsible for low compliance of cs use in cvi patients .
based on review of
patients self - report , the mediterranean climate characteristics of hot weather , high cost
of compression stockings , and difficulty to wear were the possible reasons .
it is known that venous
hypertension increases after removing stockings . in a study comparing the duration of cs
usage ,
the use of cs for entire day is more beneficial than for only half day24 . in order to decrease ambulatory venous
hypertension and to obtain maximum benefits ,
patients were asked to wear cs all day long .
the cs usage in patients was regularly checked via telephone interviews .
although venous diseases are highly prevalent , its effect on daily activities and quality
of life are not investigated thoroughly .
both general and disease - specific qol are accepted
as a standard to determine changes in qol .
the qol measurement enables better understanding
of impact of the disease while evaluating specific problem25 . in this study ,
disease - specific qol was assessed along with veines - qol whereas general qol
was assessed with nhp . at the end of one month
, significant improvement was observed in
venous symptoms , veines - qol scores and nhp parameters in group that used cs than that did
not use cs .
thus cs usage improved overall qol suggested by improvement in both
disease - specific and general qol scores . in earlier study ,
the use of two different cs for a two - week duration was found to be
beneficial for qol in both groups26 .
the
use of class 1 ( 1015 mmhg ) cs for four weeks significantly increased qol compared with and
placebo pressure ( 36 mmhg ) stockings27 .
in a similar study , it was observed that a four - week use of cs increases qol and improves
symptoms of cvi28 .
the decrease of qol in cvi is based on physical function and mobility in addition to
depression and social isolation .
depression limits performance in physical , social , and
personal activities leading to disability27 .
it was reported that 68% of the patients with venous ulceration
suffer fear , depression , social isolation , anger , anxiety , and negative self - image29 . however , there is inadequate research on
evaluation of depression level in venous diseases and use of scales in directly evaluating
depression . in earlier study in patients with venous ulcers and bdi ,
the scale is used to
determine presence of various levels of depression30 . in this study ,
depression was assessed by bdi and short - term use
of cs decreased venous symptoms in cvi patients , improved daily activities , independence
levels and thus significantly decreased depression levels when baseline and final bdi
results were compared in the study group .
therefore , regular and long - term use of cs will
improve well being of cvi patients .
this study was aimed to assess short - term effects of cs use in cvi patients .
although these
patients should have been followed up for longer term , long - term monitoring was not possible
due to transportation difficulties , family reasons , and financial problems .
nevertheless , we
contacted the patients from control group and educated them about the short - term benefits of
cs use . due to risk of development of venous ulcers in the advanced stages of cvi
, the regular use
of stocking starting from the early stages is recommended to prevent occurrence of cvi
symptoms .
further studies are necessary to evaluate the effect of cs use by cvi patients in
turkish economy and financial burden on cvi individuals in turkey . based on the findings of
this study ,
if the patients could be convinced to use cs for short - term duration , the
favourable effects will promote long - term use . | [ purpose ] this study was aimed to analyse the effects of short - term use of compression
stockings ( cs ) on symptoms and qol in patients with chronic venous insufficiency ( cvi ) .
[ subjects and methods ] based on the ceap classification c2 and c3 , 117 patients with cvi
were enrolled in this study .
the participants were divided into two groups .
the control
group refused to use cs , however , was advised to do exercises and take skin care whereas
the cs group used cs and performed exercise .
the data were collected by using nottingham
health profile ( nhp ) , venous insufficiency epidemiological and economic study
( veines - qol / sym ) and beck depression inventory ( bdi ) at baseline and after four weeks of
treatment and compared within and in between groups . [ results ] the comparison of pre- and
post - treatment differences between groups was statistically significant for all
parameters . in the study group , pre- and post - treatment scores for each parameter were
significantly different . however , elevated scores in the control group suggested worsening
of the illness .
[ conclusion ] this study established that short - term use of cs in patients
with cvi significantly improved disease specific and general qol by reducing venous
symptoms .
further studies with larger sample size are necessary to confirm these
findings . |
currently , two instruments are used to assess intraocular lens ( iol ) power : the ultrasound ( us ) a - scan and optical biometry based on partial coherence interferometry ( pci )
some authors have shown better refractive predictability with pci than with contact us,12345 whereas others have shown comparable results between pci and immersion us.67 the lenstar ( haag - streit ag , koeniz , switzerland ) and iolmaster ( carl zeiss , jena , germany ) biometers have been used to make accurate biometry measurements for choosing iol power on the basis of predicted postoperative refractive outcomes .
previous studies have reported the accuracy and repeatability of ocular biometry by use of the lenstar biometer.89 in addition , ocular biometry measurements by use of the lenstar instrument show a high degree of consistency with measurements made by use of the pci - based iolmaster biometer and a - scan.8 the manufacturer 's recommended a - constants are based on us measurements and thus may not be directly transferable to measurements obtained by using light - based pci .
previous studies have proven that optimization produces more favorable outcomes for predicting refraction with the use of pci after cataract surgeries.101112 however , no study has been published on the benefits of optimization of the iol constant and the factors related to the accuracy of iol power calculation by use of the lenstar biometer .
the purpose of this study was to evaluate and compare refractive outcomes obtained by conventional methods ( manual and automated keratometer with contact us ) and by use of the lenstar biometer with and without iol - constant optimization .
factors affecting the accuracy of iol power calculations by lenstar with and without iol - constant optimization were also investigated .
study subjects included a total of 86 patients ( 100 eyes ) who underwent uncomplicated phacoemulsification surgery with in - the - bag iol implantation in the department of ophthalmology , chonnam national university hospital , between may 2013 and october 2013 .
informed consent was obtained from each subject enrolled in this study . the chonnam national university hospital institutional review board reviewed and approved the study protocol .
all study conduct adhered to the tenets of the declaration of helsinki . before surgery , the patients underwent assessments of uncorrected visual acuity and best corrected visual acuity , manifest refraction and slit - lamp examination , intraocular pressure measurement with goldmann applanation tonometry , and dilated fundus examination .
corneal curvature was measured by using lenstar ( haag - streit ag ) , an automated keratometer ( kr 8900 ; topcon , tokyo , japan ) , and a manual keratometer ( bausch & lomb , rochester , ny , usa ) .
axial length ( al ) was also measured with lenstar and a - scan ( mentor ; mentor o & o inc . ,
the average time of examination with the lenstar was 1 or 2 minutes in all patients .
patients with posterior capsular opacification , mature cataracts , previous ocular surgery other than cataract surgery , intraoperative complications , postoperative visual acuity less than 6/12 , or poor cooperation were excluded from this study .
the surgeries were performed with the use of topical anesthesia by one surgeon . a temporal corneal incision , continuous curvilinear capsulorrhexis , hydrodissection , and phacoemulsification with the infinity machine ( alcon , fort worth , tx , usa ) were performed to remove the cataract .
the iols used in the study were one - piece acrylic iols ( sn60wf ; alcon ) .
manifest refraction , uncorrected visual acuity , best corrected visual acuity , and intraocular pressure were assessed four times postoperatively : at 1 week , 2 weeks , 1 month , and 2 months after the surgery .
iol power calculations were obtained by measurements with ( 1 ) automated keratometer and a - scan ( ak + a ) , ( 2 ) manual keratometer and a - scan ( mk + a ) , ( 3 ) lenstar without iol - constant optimization ( lw
/ oo ) , and ( 4 ) lenstar with iol - constant optimization ( lwo ) . the iol power calculation with lenstar
the target was emmetropia using the srk / t formula ( recommended and previously optimized ultrasound a - constant , 118.7 ; lenstar optimized a - constant , 119.02 ) .
the optimized iol constant was obtained from east valley ophthalmology ( mesa , az , usa ; www.doctor-hill.com ) .
the final refraction [ spherical equivalent ( se ) ] was measured by using an autorefractometer ( kr 8900 ; topcon ) at 2 months postoperatively .
mean absolute error ( mae ) was defined as the average absolute value of the numerical error ( ie , the final postoperative se minus the predicted postoperative se ) .
accuracy was analyzed by comparing the mean numerical errors ( mnes ) and maes among devices . the distribution and proportion of maes within 0.5 to 2.0 d were investigated .
factors related to the accuracy of iol power calculation included severity of nuclear sclerosis , corneal curvature , spherical equivalent , and al before cataract surgery ; the statistical significance of these factors on maes was investigated .
severity of nucleosclerosis was determined by using the lens opacities classification system ( locs ) iii classification ( mild : no2/nc2 , moderate : > no2/nc2 and no4/nc4 , and severe : >
the als were categorized into three groups : shorter than 23 mm , 23 to 25 mm , and longer than 25 mm .
corneal curvature was also categorized into three groups : smaller than 42 d , 42 to 44 d , and larger than 44 d.13 spss version 18.0 for windows ( spss inc . , chicago , usa ) and medcalc ( medcalc , mariakerke , belgium ) were used .
corneal curvature measurements were compared among the three instruments by using analysis of variance ( anova ) .
bland - altman plots were used to assess the level of agreement ( loa ; width of the 95% limits of agreement ) .
the kruskal - wallis test was used to test the difference among instruments for mne and mae .
the student 's t - test and kruskal - wallis test were used to analyze the factors affecting mae .
before surgery , the patients underwent assessments of uncorrected visual acuity and best corrected visual acuity , manifest refraction and slit - lamp examination , intraocular pressure measurement with goldmann applanation tonometry , and dilated fundus examination .
corneal curvature was measured by using lenstar ( haag - streit ag ) , an automated keratometer ( kr 8900 ; topcon , tokyo , japan ) , and a manual keratometer ( bausch & lomb , rochester , ny , usa ) .
axial length ( al ) was also measured with lenstar and a - scan ( mentor ; mentor o & o inc . ,
the average time of examination with the lenstar was 1 or 2 minutes in all patients .
patients with posterior capsular opacification , mature cataracts , previous ocular surgery other than cataract surgery , intraoperative complications , postoperative visual acuity less than 6/12 , or poor cooperation were excluded from this study .
the surgeries were performed with the use of topical anesthesia by one surgeon . a temporal corneal incision , continuous curvilinear capsulorrhexis , hydrodissection , and phacoemulsification with the infinity machine ( alcon , fort worth , tx , usa ) were performed to remove the cataract .
the iols used in the study were one - piece acrylic iols ( sn60wf ; alcon ) .
manifest refraction , uncorrected visual acuity , best corrected visual acuity , and intraocular pressure were assessed four times postoperatively : at 1 week , 2 weeks , 1 month , and 2 months after the surgery .
iol power calculations were obtained by measurements with ( 1 ) automated keratometer and a - scan ( ak + a ) , ( 2 ) manual keratometer and a - scan ( mk + a ) , ( 3 ) lenstar without iol - constant optimization ( lw
/ oo ) , and ( 4 ) lenstar with iol - constant optimization ( lwo ) . the iol power calculation with lenstar
the target was emmetropia using the srk / t formula ( recommended and previously optimized ultrasound a - constant , 118.7 ; lenstar optimized a - constant , 119.02 ) .
the optimized iol constant was obtained from east valley ophthalmology ( mesa , az , usa ; www.doctor-hill.com ) .
the final refraction [ spherical equivalent ( se ) ] was measured by using an autorefractometer ( kr 8900 ; topcon ) at 2 months postoperatively .
mean absolute error ( mae ) was defined as the average absolute value of the numerical error ( ie , the final postoperative se minus the predicted postoperative se ) .
accuracy was analyzed by comparing the mean numerical errors ( mnes ) and maes among devices . the distribution and proportion of maes within 0.5 to 2.0 d were investigated .
factors related to the accuracy of iol power calculation included severity of nuclear sclerosis , corneal curvature , spherical equivalent , and al before cataract surgery ; the statistical significance of these factors on maes was investigated .
severity of nucleosclerosis was determined by using the lens opacities classification system ( locs ) iii classification ( mild : no2/nc2 , moderate : > no2/nc2 and no4/nc4 , and severe : > no4/nc4 ) .
the als were categorized into three groups : shorter than 23 mm , 23 to 25 mm , and longer than 25 mm .
corneal curvature was also categorized into three groups : smaller than 42 d , 42 to 44 d , and larger than 44 d.13
, chicago , usa ) and medcalc ( medcalc , mariakerke , belgium ) were used .
corneal curvature measurements were compared among the three instruments by using analysis of variance ( anova ) .
bland - altman plots were used to assess the level of agreement ( loa ; width of the 95% limits of agreement ) .
the kruskal - wallis test was used to test the difference among instruments for mne and mae .
the student 's t - test and kruskal - wallis test were used to analyze the factors affecting mae .
corneal curvatures measured by mk , ak , and lenstar were 43.981.49 d , 43.921.49 d , and 43.861.49 d , respectively ( table 1 ) .
no statistically significant difference was found in the corneal curvatures obtained by using the three instruments ( p=0.85 ) .
the measurements of al obtained by using lenstar were significantly higher than those obtained by using a - scan ( 23.371.13 mm versus 23.201.13 mm ; p<0.01 ) . however , bland - altman plots of keratometry and al data revealed excellent agreement between instruments with a 95% loa ( figs . 1 and 2 ) .
the mnes were -0.110.51 , -0.190.55 , -0.240.58 , and -0.210.61 for mk + a , ak + a , lw / oo , and lwo , respectively .
there were no significant differences in mne between the methods used for iol power calculation ( p=0.13 ) .
the maes were 0.500.40 , 0.510.43 , 0.670.52 , and 0.550.49 for mk + a , ak + a , lw / oo , and lwo , respectively .
the proportions of mae within 0.5 d were 62% , 58% , 46% , and 62% for mk + a , ak + a , lw / oo , and lwo , respectively
. the respective ratios of mae within 1.0 d were 86% , 84% , 76% , and 82% ( table 2 ) . in the analysis of the factors affecting the iol power calculation by use of lenstar with and without iol - constant optimization , severity of nucleosclerosis and preoperative
without iol - constant optimization , the mae was significantly smaller in eyes with als between 23 and 25 mm than in eyes with an al shorter than 23 mm or longer than 25 mm ( p=0.03 ; table 3 ) .
with iol - constant optimization , the mae was significantly smaller in the eyes with corneal curvature greater than 44 d ( p=0.03 ; table 4 ) .
in contrast , the mae was larger when the corneal curvature was less than 44 d.
in cases involving cataract surgery , preoperative iol power calculations are indispensable for reaching the desired postoperative goal .
an error of 0.1 mm in al measurement can lead to mae values of 0.25 d to 0.75 d. an error of 0.5 d in the keratometric reading also can lead to a refractive error of 1.17 d.14 in this study , we found a high degree of consistency between corneal curvature and als measured by lenstar and measurements made by other instruments .
the previous study also demonstrated that ocular biometric findings obtained by using a - scan , iol master , and lenstar were highly comparable.9 however , another study reported that the al values in eyes with cataracts were significantly longer when measured by lenstar than when measured by a - scan.15 our study also showed that als obtained by using lenstar were 0.17 mm higher than als measured by use of a - scan .
second , al is measured at the level of the retinal pigment epithelium and not the internal limiting membrane .
constant optimization is the process by which the iol constant is adjusted to minimize systematic errors.16 the process of constant optimization has little effect on the distribution of outcomes around the mean,16 but maximizes the proportion of eyes within a particular target range and minimizes the mae .
iol constant optimization has been shown to significantly improve prediction accuracy for contact us ( from 79.7% to 82.5% within 1.0 d),17 immersion us ( from 60.0% to 65.0% within 0.5 d),11 and optical biometry ( from 76 - 89% to 92 - 94% within 1.0 d , dependent upon iol model and formula).12 the previous study reported that serial modifications to the a - constant were successful in reducing the unexpected errors.10 other studies found significant improvement in iol power prediction and refractive outcomes when using iolmaster with optimized a - constants , generating refractive errors of < 0.25 d in 40% ,
< 0.50 d in 75% , and < 1.0 d in 95% of eyes.18 however , no study has reported differences in refractive outcomes by use of lenstar with and without iol - constant optimization . furthermore , this is first report that has analyzed the factors related to the accuracy of iol power calculation with the use of the lenstar biometer .
we evaluated mne and mae with and without iol - constant optimization by use of the lenstar biometer .
the mne and mae were also compared with values based on the refractive power obtained by mk + a and ak + a. the mne and mae did not differ significantly between groups .
however , measurement accuracy is better characterized by the proportion of eyes under the refractive value limits of 0.5 d and 1.0 d. the ratios of mae within 0.5 d and 1.0 d using lwo ( 62% and 82% ) were superior to those using lw / oo ( 46% and 76% ) .
furthermore , the results of mae within 0.5 d or 1.0 d using lw / oo were worse than those of conventional methods .
previous studies have shown various effects of al , keratometry , and the severity of cataract on the precision of iol power calculations with iolmaster.192021 ueda et al.19 reported that postoperative outcome was affected by cataract density using iolmaster .
hsieh and wang,13 however , reported that many factors , including age , al , keratometry , severity of cataract , and dm status exerted no effects on iol power predictability regardless of the iol power calculation method using iolmaster or a - scan . in the present study , we investigated preoperative factors that affected the accuracy of iol power calculation with and without iol - constant optimization with the use of lenstar .
we found that various factors , including the severity of nuclear sclerosis and preoperative spherical equivalent , had insignificant effects on mae regardless of iol - constant optimization .
however , before iol - constant optimization , al had a significant effect only when it was either longer than 25 mm or shorter than 23 mm .
hsemeyer et al.21 reported that the difference in refractive error using iolmaster was significantly larger in eyes with an al shorter than or equal to 23.2 mm than in eyes with an al longer than 23.2 mm .
kim et al.22 also demonstrated that eyes with an al 23 mm showed significantly greater hyperopic shifts in postoperative refraction . however , song et al.3 reported that the mae increased in eyes with an al longer than 25 mm .
the previous study reported a trend that the mae was smaller in the group with keratometric readings less than 42 d when autorefractometer , ultrasound , and iolmaster were used , but not significantly.13 in the present study , after iol - constant optimization , on the other hand , corneal curvature led to significant differences in mae ( > 44 d ; p=0.03 ) .
additional studies of the different factors affecting iol power calculation using lenstar according to iol constant optimization will be needed in the future .
first , our study had a retrospective design involving a relatively small number of patients .
third , we did not compare our results with rotating scheimpflug imaging , scanning slit corneal topography , and iolmaster , which have been broadly used for iol - power calculation .
fourth , we did not compare various iol - power calculation formulas . in conclusion ,
lenstar with iol - constant optimization improved the prediction of refractive power compared with lenstar without iol - constant optimization after cataract surgery .
the refractive outcomes of the conventional method were as accurate as lenstar with iol - constant optimization .
however , the results of mae within 0.5 or 1.0 d using lenstar without optimization were worse than those of conventional methods .
the al can influence the accuracy of refractive outcomes determined by using lenstar without iol - constant optimization ; whereas , with iol - constant optimization , significant differences depend on corneal curvature .
therefore , our results suggest that these factors should be taken into consideration before cataract surgery . | this retrospective study was performed to compare refractive outcomes measured by conventional methods and by use of the lenstar biometer and to investigate the factors affecting intraocular lens ( iol ) power calculation with lenstar with and without iol - constant optimization .
the study included 100 eyes of 86 patients who underwent cataract surgery .
corneal curvature was measured with a manual keratometer ( mk ) , automated keratometer ( ak ) , and the lenstar biometer , and axial length ( al ) was measured by a - scan and lenstar .
mean numerical error ( mne ) and mean absolute error ( mae ) were compared between ak and mk with a - scan , and lenstar with and without optimization .
factors affecting the accuracy of the iol power calculation by use of lenstar with and without optimization were analyzed .
no significant differences were observed in the mne or mae among the devices .
the proportion of mae within 0.5 d was higher for lenstar with optimization ( 62.7% ) than without optimization ( 46.2% ) .
the proportion of mae within 0.5 d was 62% and 58% for mk and ak with a - scan , respectively . without optimization ,
the mae was smaller in eyes with als between 23 mm and 25 mm ( p=0.03 ) , whereas it was smaller at higher corneal powers when the iol constant was optimized ( > 44 d , p=0.03 ) .
the iol power calculations showed no significant differences among the devices , but the results of mae within 0.5 d by use of lenstar without optimization were worse than those of conventional methods .
the al influenced the accuracy of refractive outcomes determined by using lenstar without optimization , and corneal curvature was shown to affect the accuracy of refractive measurements using lenstar with optimization . |
SECTION 1. TEACHER RECRUITMENT.
Subpart 1 of part A of title IV of the Higher Education Act of 1965
is amended--
(1) in chapter 3, by redesignating section 407E (20 U.S.C.
1070a-35) as section 406E; and
(2) by inserting after such chapter 3 the following new
chapter:
``CHAPTER 4--FUTURE MATH AND SCIENCE TEACHER RECRUITMENT
``SEC. 407A. SHORT TITLE; FINDINGS.
``(a) Short Title.--This chapter may be cited as the `Recruit and
Reward Future Math and Science Teachers of America Act of 2001'.
``(b) Findings.--Congress finds the following:
``(1) United States high school students rate 16th and
19th, respectively, in science and math out of 21 countries.
``(2) Of United States high school students who take math
courses, 22 percent are taught by teachers who did not prepare
in that field.
``(3) Of United States high school students who take
biology courses, 24 percent are taught by teachers who did not
prepare in that field.
``(4) Of United States high school students who take
chemistry courses, 30 percent are taught by teachers who did
not prepare in that field.
``(5) Of United States high school students who take
physics courses, 56 percent are taught by teachers who did not
prepare in that field.
``(6) Teachers' knowledge and skills powerfully influence
student learning.
``(7) More than 2,000,000 teachers will need to be hired
over the next decade.
``(8) The ability of the United States to place highly
qualified math and science teachers specializing in their field
of instruction will depend on proactive policies that increase
funding for teacher training, recruitment, and induction.
``SEC. 407B. PURPOSE; APPROPRIATIONS AUTHORIZED.
``(a) Purpose.--It is the purpose of this chapter to make grants
available, through a pilot program, to eligible institutions described
in section 407C, to enable such institutions to provide 500 scholarship
awards to outstanding students enrolled in an accredited teacher
training graduate program who are committed to pursuing careers
teaching math and science at an urban or rural secondary level
classroom.
``(b) Authorization of Appropriations.--There are authorized to be
appropriated to carry out this chapter $5,000,000 in each of the fiscal
years 2002, 2003, and 2004.
``SEC. 407C. SCHOLARSHIP DESIGNATION AND SELECTION CRITERIA.
``(a) Scholarship Designation.--Funds made available under this
chapter shall be designated as the `National Math and Science Teacher
Scholarships'.
``(b) Selection Criteria.--The Secretary of Education may award
funds for National Math and Science Teacher Scholarships on a
competitive basis to qualifying institutions of higher education that
have graduate programs in teacher training. The Secretary may not
provide any individual institution of higher education with more than
$100,000 per academic year for the purpose of the National Math and
Science Teacher Scholarships. An institution applying for such
scholarships may only be eligible to receive funds if such institution
is ranked by the Secretary in the top 25 percent of schools in the
State in which the institution is located with the highest percentage
of graduates passing the State teacher qualification assessment for new
teachers. Notwithstanding the preceding sentence, if there are fewer
than 4 such institutions in a State, only the institution with the
highest percentage of such graduates shall be eligible to receive
funding.
``(c) Priorities.--The Secretary shall give priority to eligible
institutions that meet 1 or more of the following criteria:
``(1) Provide a year long internship program in a
professional development school.
``(2) Provide mentoring programs for novice teachers in
their first 3 years.
``(3) Demonstrate a history of placing graduates in rural
and urban schools.
``(4) Demonstrate that there is a high retention rate of
teachers that the institution places in teaching positions.
``SEC. 407D. INDIVIDUAL SCHOLARSHIP ELIGIBILITY.
``An individual may be eligible for a National Math and Science
Teacher Scholarship only if such individual--
``(1) is a citizen or national of the United States or an
alien lawfully admitted to the United States for permanent
residence;
``(2) is majoring in a physical or life science or
mathematics graduate teacher training program;
``(3) is enrolled in a higher education institution that--
``(A) is ranked by the Secretary in the top 25
percent of schools in the State in which the
institution is located with the highest percentage of
graduates passing the State teacher qualification
assessment for new teachers; or
``(B) if there are fewer than 4 such institutions
in a State, is the institution with the highest
percentage of such graduates; and
``(4) is willing to teach math or science in a rural or
urban public secondary school for no less than 3 full academic
years.
``SEC. 407E. SCHOLARSHIP AMOUNT.
``(a) Amount of Award.--
``(1) In general.--The amount of a scholarship awarded by
participating teacher training graduate programs under this
chapter for any academic year shall be $10,000 per student,
except that in no case shall the total amount of the
scholarship exceed the total cost of attendance.
``(2) Insufficient funds.--In any fiscal year in which the
amount appropriated to carry out this chapter is insufficient
to award 500 scholarships, the Secretary shall reduce the
number of awards to eligible institutions.
``(b) Assistance Not To Exceed Cost of Attendance.--No individual
shall receive an award under this chapter in any academic year which
exceeds the cost of attendance. A scholarship awarded under this
chapter shall not be reduced on the basis of the student's receipt of
other forms of Federal student financial assistance.
``SEC. 407F. AGREEMENT; SCHOLARSHIP REPAYMENT PROVISIONS.
``(a) Agreement.--Recipients of the National Math and Science
Teachers Scholarships shall agree to teach in an urban or rural public
secondary school for no less than 3 full academic years.
``(b) Repayment for Failure To Fulfill Agreement.--Any recipients
of a Scholarship found by the Secretary to be in noncompliance with the
agreement entered into under subsection (a) of this section shall be
required to repay a pro rata amount of the scholarship awards received,
plus interest and, where applicable, reasonable collection fees, on a
schedule and at a rate of interest prescribed by the Secretary by
regulations.
``SEC. 407G. EXCEPTIONS TO REPAYMENT PROVISIONS.
``An individual recipient of a Scholarship under this chapter shall
not be considered in violation of the agreement entered into pursuant
to section 407F during any period in which the recipient--
``(1) is pursuing a full-time course of study in math and
science at an accredited institution;
``(2) is serving, not in excess of 3 years, as a member of
the armed services of the United States;
``(3) is temporarily disabled for a period of time not to
exceed 3 years as established by sworn affidavit of a qualified
physician;
``(4) is seeking and unable to find full-time employment
for a single period not to exceed 12 months;
``(5) is seeking and unable to find full-time employment as
a math and science teacher in a public or private nonprofit
elementary or secondary school or education program for a
single period not to exceed 27 months;
``(6) satisfies the provision of additional repayment
exceptions that may be prescribed by the Secretary in
regulations issued pursuant to this section; or
``(7) is permanently totally disabled, as established by
sworn affidavit of a qualified physician.
``SEC. 407H. REPORT TO CONGRESS.
``Three years after the date on which funds are first made
available to carry out this chapter, the Secretary of Education shall
submit a report to Congress evaluating the success of the National Math
and Science Teacher Scholarships pilot program in recruiting math and
science teachers to teach in America's public secondary schools.''. | Recruit and Reward Future Math and Science Teachers of America Act of 2001 - Amends the Higher Education Act of 1965 to establish the National Math and Science Teacher Scholarships pilot program to recruit and train future secondary school mathematics and science teachers.Authorizes the Secretary of Education to award competitive grants to higher education institutions with graduate programs in teacher training to make such scholarships to outstanding students enrolled in such programs who are committed to pursuing careers in secondary school mathematics and science teaching.Makes institutions eligible only if they are ranked by the Secretary in the top 25 percent of schools in their States with the highest percentage of graduates passing the State teacher qualification assessment for new teachers. Gives priority to institutions with one or more of the following: (1) a year-long internship program in a professional development school; (2) mentoring programs for novice teachers in their first three years; (3) a history of placing graduates in rural and urban schools; and (4) a high retention rate of teachers that the institution places in teaching positions.Requires scholarship recipients to agree to teach in an urban or rural public secondary school for at least three full academic years, or repay the pro rata amount of awards received, plus interest, for any failure to fulfill such obligation, with specified exceptions. |
asthma is a common condition that affects 5 - 10% of the population worldwide.1 al - though known since antiquity , asthma has only recently been defined as being only partially reversible.2 it places a substantial burden on family , health care services and on society as a whole . in children , it im - pairs ability to enjoy or take part in sporting events , it affects sleep patterns and school attendance . in adults
, it affects the quality of life and days of work.34 it is widely accepted that there is an increase in morbidity and mortality due to bronchial asthma.5 this may be attributed to environmental and social changes such as rapid urbanization , increased exposure to indoor allergens and occupational exposure.16 in the kingdom of saudi arabia , the prevalence of asthma was 12% , with vast regional variations ranging from less than 10% in dammam to 23% in hail.7 bahrah is a semiurban area in the middle of the desert along the highway between makkah and jeddah .
two brick factories are located near houses in the city . in the last few years
the number of asthma cases attending local primary health care centers ( phccs ) has risen .
a case control design was used to execute the study . assuming that the prevalence of exposure among the controls was 20% , study power of 80% at 95% confidence level with 1:1 case control ratio , a sample size of 110 cases and 110 controls was determined .
all cases of bronchial asthma residing in bahrah diagnosed by treating physicians and consistent with diagnostic criteria of asthma in the national protocol1 and attending the outpatient clinics of the two phccs in bahrah were included until the predetermined sample size was recruited .
for each case , a control of corresponding age and sex was chosen from visitors to phccs in bahrah with no history of asthma , nor complaint of respiratory symptoms .
data were collected by means of a struc - tured questionnaire completed by personal interviews with cases and controls .
data consisted of personal characteristics , e.g. age , sex , medical history and environ - mental exposures , e.g. to indoor plants , ani - mals and smoking . to determine the distance from houses to brick factories a map of the city drawn to the scale of 1.5 :
the houses were located on the map and the distance to the nearest factory was measured and converted into actual distances .
cases were considered severe if they reported history of admission to hospital as a result of asthma .
chi - square for linear trend was used to assess association between bronchial asthma and distance from houses to factories . the odds ratio and its 95% confidence interval were used as a measure of risk .
factors found to be significantly associated with asthma in bivariate analysis were submitted to multivariate logistic regres - sion analysis for control of confounders .
each group consisted of 64 males ( 58% ) and 46 ( 42% ) females .
the mean ages for cases and con - trols were 22.4 ( 16.7 ) and 22.8 ( 16.1 years ) , respectively .
table 1 shows that there is no association between education and bronchial asthma ( p>0.05 ) .
the risk of asthma is significantly higher among housewives and students than other groups ( or=3.29 , ci=1.21- 9.02 and or= 2.92 , ci=1.42 - 7.03 , respectively ) .
persons with family history of asthma face more than five - fold the risk of its occurrence compared to those without such history ( or=5.45 , ci=2.93 - 10.2 ) .
persons suffering from allergic rhinitis , skin atopy or
recurrent respiratory infections face an increased risk of asthma ( or=9.89 , ci=4.87 - 20.31 ; or=6.31 , ci=2.55 - 17.67
and or=10.5 , ci=5.11 - 21.89 respectively ) .
table 2 reveals the risk of asthma to be significantly high among persons living in houses with concrete courtyards , or with pets ( or=2.45 , ci=1.26 - 5.01 and or= 2.29 , ci=1.02 - 5.17 , respectively ) .
the risk of asthma is also high , but not statistically significant , among persons who have indoor plants or those who use chemical cleansing agents ( or=1.43 , ci=0.79 - 2.62 and or=1.99 , ci=0.37 - 13.15 respectively ) .
personal factors among cases and controls of bronchial asthma in bahrah , saudi arabia environmental factors among cases and controls of bronchial asthma in bahrah , saudi arabia table 3 shows that there is significant linear association between both the occurrence and severity of bronchial asthma with the distance from houses and brick factories ( p<0.001 ) .
the highest risk was among those living within one kilometer of the factories ( or=10.2 , ci=3.07 - 38.63 and or=9.27 , ci= 2.79 - 35.23 , respectively ) .
there was no linear trend between distance from the main road in bahrah and occurrence of asthma ( p>0.05 ) .
distance between houses of cases and controls of bronchial asthma and brick factories and roads in bahrah , saudi arabia table 4 shows the result of multivariate logistic regression analysis of factors found to be significantly associated with asthma in bicariate analysis .
persons living within more than five - fold the risk of asthma compared to those living further away ( or=5.1 , ci=2.33 - 11.16 ) .
also , persons with posi - tive family history of asthma , skin atopy , allergic rhinitis and recurrent respiratory infections are at high independent risk of asthma ( or=4.6 , ci=2.16 - 9.7 ; or=4.6 , ci=1.53 - 13.87 ; or=3.4 , ci=1.49 - 7.69 and or=4.1 , ci=1.79 - 9.22 , respectively ) .
asthma is the most common chronic disease in children3 and an important disease among adults.38 risk factors of asthma vary from place to place according to several factors , including urbanization.9 this study revealed that allergic rhinitis and atopic dermatitis increased the risk of asthma .
many other studies support this finding and have shown the co - existence of allergic rhinitis and asthma.1013 zhao et al used multivariate logistic regression anal - ysis and found a high significant risk of asthma among persons with allergic rhinitis or itchy rash.14 el - gamal et al reported independent association between personal history of allergy and bronchial asthma.15 immunological studies have shown that children with atopic dermatitis present non - specific bronchial hyperactivity ( 58 - 82% ) which is a risk factor for later development of asthma.1617 recurrent respiratory tract infections were found to be an independent risk factor for bronchial asthma in the present study ( or=4.1 , ic=1.79 - 9.22 ) .
paul et al con - sidered viral respiratory diseases as a defined risk factor for developing asthma.18 martinez et al found also that recurrent lower respiratory tract infection in early life triggers the development of asthma later in life.19 the present study revealed that persons with family history of bronchial asthma were at high risk of developing asthma ( or=4.6 , ci=2.169.78 ) .
the same finding was reported by infante - rivard who found increased significant risk of asthma among those with familial history of asthma.20 al - frayh et al supported this finding and reported that 35.9% of children who wheeze have mothers with asthma and 40.7% have fathers with asthma.21 studies of twins have shown a significant increase in concordance among monozygotic twins compared to dizygotic twins , providing evidence for genetic predisposition.22 how - ever , no gene or genes involved in the inheritance of atopy and asthma have been identified.23 environmental tobacco smoke was suggested as a risk factor for bronchial asthma.2425 the present study did not support this suggestion . in children , this inconsistency may be explained by the observation that more parents whose children had been diagnosed as asthmatic had quit smoking than parents of healthy controls.26 in agreement with the present finding , pewits found that smoking does not appear to be related to asthma per se in adults when chronic conditions are removed and those at risk do not smoke , quit smoking or smoke very little.27 distance from home to brick factory as a measure of exposure to air pollution was found to be a significant risk factor for both the occurrence and severity of asthma .
living near these factories ( 1 km . ) carried the highest risk ( or=5.1 , ci=2.33 11.16 ) .
this pollutes air with so2 , no2 , co2 and co particles.28 several mechanisms have been proposed to explain the pollution - induced asthma .
these include damage to airway epithelium , induced changes in lung function and enhanced release of inflammatory mediators.29 this study shows the presence of animals at home to be a risk factor for asthma ( or=2.27 ) . however , the risk was not statistically significant ( ci= 0.935.55 ) .
many investigators have studied the etiological significance of animal handlers and suggested that they had high risk of asthma.3031 regarding the role of exposure to indoor plants , the present study reveals an insignificant association between indoor plants and asthma ( or= 1.43 , ci=0.79 2.62 ) .
this finding is inconsistent with reports of high sensitization of allergic patients to regional pollens.32 the inconsistency may be due to differences in exposure to specific regional pollens .
precise measurement of pollen allergens can also give more accurate results about the role of plants and pollens .
the lack of precise measurement for detailed environmental factors and the small sample size were the main limitations of the present work .
an in - depth environmental study to assess the levels of air pollutants in bahrah is highly recommended .
atopic diseases , e.g. allergic rhinitis and atopic dermatitis , should be prevented through the avoidance of inhalant and cutaneous allergens , parti - cularly by those with positive family history of asthma . | background : asthma is a common health problem whose prevalence in saudi arabia has risen over the last few decades .
brick factories in the city of bahrah have exacerbated the problem , and increasing numbers of asthma cases are attending local primary health care centers.objective:determine the risk factors of asthma in bahrah.materials and methods : the study was comprised of 110 cases of bronchial asthma resident in bahrah who were diagnosed by the treating physicians and 110 healthy controls matched in age and sex .
a questionnaire was completed from cases and controls , consisting of data regarding personal , familial , indoor and outdoor environmental factors that may be potential risk factors to asthma .
bivariate and multivariate logistic regression analyses were done to assess risk factors.results:the mean ages of cases and controls were 22.4 ( 16.7 ) and 22.8 ( 16.1 ) years , respectively .
each group consisted of 64 males ( 58% ) and 46 ( 42% ) females .
there was a significant association between distance from houses to brick factories and bronchial asthma ( chi square for linear trend = 26.6 , p<0.001 ) .
multivariate logistic regression analysis showed that living within one kilometer of a brick factory ( or=5.1 , ci=2.33 - 11.16 ) , family history ( or=4.6 , ci=2.16 - 9.78 ) , allergic rhinitis ( or=3.39 , ci=1.49 - 7.69 ) , skin atopy ( or=4.6 , ci=1.53 - 13.87 ) and recurrent respiratory tract infections ( or=4.1 , ci=1.79 - 9.22 ) were independent risk factors for asthma in bahrah.conclusions and recommendations : brick factories , family history and history of rhinitis , skin atopy , or recurrent respiratory tract infections are risk factors of bronchial asthma .
an in - depth study to asses air pollution in bahrah is recom - mended .
people are advised not to live near brick factories . |
Wanted teen Ethan Couch and his mother may be traveling together in her pickup truck, Tarrant County authorities said Monday at a news conference on the nationwide manhunt.
Investigators are sifting through “hundreds and hundreds” of leads — including flight, credit card and cell phone records — as they search for Couch, 18, and his mom, Tonya Couch, 48.
The teen has been wanted since Dec. 11, after he missed his probation meeting, authorities said. Couch’s notorious “affluenza” defense in 2013 spared him jail time for killing four innocent bystanders in a drunk-driving crash. Another victim, a teenager, was left severely brain damaged and paralyzed.
Former District Judge Jean Boyd sentenced Couch to probation — a “miscarriage of justice” that continues to enrage many in Tarrant County, said Sheriff Dee Anderson.
“He continues to believe the law doesn’t apply to him, which is how he was raised,” said Anderson, who was visibly angry at a news conference Monday. “If he has enough money, he can get out of it.”
Anderson said Couch showed no remorse or sympathy the night he killed the victims or afterward. Couch, then 16, who had been drinking at his parents’ second home in Burleson, got behind the wheel with seven people piled into his Ford pickup, authorities said.
That night, Couch had a blood alcohol content of 0.24 — three times the legal limit for an adult — and was driving 70 mph in a 40-mph zone, authorities said.
“I said then, we’re not through with Ethan Couch — he’s not the kind of person who rehabilitates, who learns his lesson,” Anderson said.
Authorities asked for the public’s help in finding Tonya Couch’s Ford pickup truck. It’s a black 2011 Ford F150 Harley Davidson edition with 23 inch chrome wheels and Texas license plate BC50945. There’s damage to the pickup — a “crease” on the passenger side panel.
Couch’s attorneys, Scott Brown and Reagan Wynn, released a short statement saying they learned that Couch’s probation officer hasn’t been able to reach him or his mother for “the last several days,” prompting the court to call for his detention. The attorneys declined further comment.
Authorities said they’re not sure the teen and his mom are together, or that she is helping him elude law enforcement. But investigators have a “strong suspicion” that’s the case, Anderson said. Authorities pledged to file criminal charges against anyone proven to have helped Couch elude capture.
Anderson said he believes Couch decided to go on the run after someone tweeted a video that appeared to show Couch at a beer pong game where there was alcohol. The Twitter user wrote that Couch was violating his probation. His probation terms prohibited him from drinking alcohol, so he wanted to run from the potential jail time he faced, Anderson said.
ya boy ethan couch violating probation. i got more if u want @CityofBurleson @TarrantCountyDA pic.twitter.com/otiGprQ1uD — h (@BlondeSpectre) December 2, 2015
Tarrant County District Attorney Sharen Wilson said Couch wasn’t allowed to leave the county without asking permission from his probation officer, which he didn’t do. She declined to say whether his passport had been confiscated.
Wilson said the victims’ families are being re-traumatized by Couch’s disappearance, and Christmastime makes it even harder. Couch killed 24-year-old Breanna Mitchell, whose SUV had broken down, and three people who had stopped to help: youth pastor Brian Jennings 41, and Hollie Boyles, 52, and her daughter, Shelby Boyles, 21.
A surviving victim, Sergio Molina, 17, was left severely brain damaged and paralyzed. Another teenage survivor, Soliman Mohmand, suffered broken bones and internal injuries.
“There isn’t anything more difficult in the world than these people being without their family members and us being focused on the man who killed them,” Wilson said. “It’s just heartbreaking.”
Couch and his mother lived together by themselves, Anderson said. She was divorced from Couch’s father, Fred Couch, who cooperated with investigators right after Ethan and his mom’s disappearance, telling them he hadn’t heard from either of them in about two weeks.
Tonya Couch’s mother reported the 48-year-old missing on Sunday. That allowed authorities to enter her name in a national database with a note saying that she is possibly with a fugitive. That way, if police look her up, they will see that information, Anderson said.
Couch received 10 years’ probation last year in his intoxication manslaughter case after a psychologist testified he suffered from “affluenza” because his family’s wealth and a dysfunctional relationship with his parents left him without a sense of responsibility.
Wilson has filed to move Couch’s case to adult court. If it remains in juvenile court, she said, the maximum he could serve would be four months in detention, until he turns 19 in April. But if the case is moved to adult court, he could face 10 years in prison.
“Hopefully, we will be able to hold him accountable … and make him pay a price since he hasn’t had to do that so far,” Anderson said.
In addition to local authorities and the U.S. marshals, the FBI is also assisting with the nationwide search.
There is a $5,000 reward for information leading to Couch’s capture. Anyone with information about the case may call the U.S. Marshals Service at 800-336-0102.
The Associated Press and staff writer Claire Cardona contributed reporting. ||||| TARRANT COUNTY, Texas -- Officials released photos Monday of a pickup truck belonging to Tonya Couch, the missing mother of a wanted teen made famous when his lawyer told a Texas court the boy suffered from "affluenza."
Couch and her son, Ethan, have been missing for more than a week. Ethan Couch, who was 16 years old when he killed four pedestrians in a drunk driving crash, was sentenced in 2013 to 10 years of probation. He is required to check in with a probation officer regularly, but has allegedly been out of contact with authorities for about two weeks.
Tarrant County Sheriff Dee Anderson said at a press conference Monday morning that authorities believe the mother and son are together, and potentially fled the county in her black 2011 Ford F-150 pick-up.
Tarrant County Sheriff's Office
"We're trying to account for everything that's possible," Anderson said. "And this pickup truck is one thing we can't account for."
The truck is a Harley Davidson-themed special edition with 23 inch chrome wheels, and Texas License Plate BC-50945, according to officials. Anderson acknowledged during the press conference that investigators don't know for sure that Tonya and Ethan couch are together.
"We can't even prove that they're together, we certainly believe that they're together," Anderson said. "If she helped him in any way, we're going to file criminal charges against her."
U.S. Marshals Service
Texas sheriff's deputies, U.S. Marshals and the FBI are all searching for the Ethan Couch, whose 2013 sentence cause controversy after his lawyer argued in court that he didn't understand consequences due to his parents' wealth -- a syndrome the lawyer called "affluenza."
Authorities believe Ethan Couch fled after the Tarrant County District Attorney's Office began investigating a video that surfaced online allegedly showing the teen at a party with several people playing beer pong, a drinking game.
Tarrant County District Attorney Sharen Wilson said that while her office was looking into the video, it's not why they're now searching for Ethan Couch and his mother.
"The problem for him on the juvenile probation is that he's not here. Juveniles have to ask for permission to leave the county, and we believe he's not in the county," Wilson said.
In November, Wilson's office asked a court to move the now 18-year-old's case to adult court, where the potential repercussions for failing to follow the rules of probation are greater.
"He's looking at possible penitentiary time if he's transferred to adult court," Wilson said, of the potential punishment for Ethan Couch's disappearance.
Anderson, who is running for reelection in 2016, has conducted a media blitz while searching for Ethan Couch, appearing on national and local television regularly to give updates on the search. On Monday, he said that at the scene of Couch's deadly June 2013 car crash, "those who dealt with him at the accident scene and in the post-accident scene saw no remorse."
The 16-year-old's blood-alcohol level was three times the legal limit for an adult and there were traces of Valium in his system when he lost control of his pickup truck and plowed into a group of people helping a woman whose car had stalled.
When he was sentenced six months later to probation, there was widespread outrage in Tarrant County, and Anderson was among many public officials who decried it.
"Obviously this case is very very important to my agency," Anderson said Monday. "Unfortunately for us, my deputies had to investigate the devastating crime scene ....which resulted from the irresponsible decision that Ethan Couch made." | – "Affluenza teen" Ethan Couch, the Texas 18-year-old who allegedly violated his probation after a drunk-driving crash that killed four bystanders, is still missing along with his mother. They may be traveling in her black 2011 Ford F150 pickup truck, authorities said at a press conference Monday. The Harley Davidson edition truck has 23-inch chrome wheels, a "crease" of damage on the passenger side panel, and Texas license plate BC50945. Per the Dallas News, a "visibly angry" Tarrant County Sheriff Dee Anderson said Couch "continues to believe the law doesn’t apply to him, which is how he was raised. If he has enough money, he can get out of it." He added that investigators have a "strong suspicion" the two are together and Couch's mother is helping him flee the law, though they don't know for sure. Tonya Couch, 48, has now officially been reported missing, CBS News reports. That means she's in a national database for missing persons, and authorities added a note saying she might be with a fugitive, which police will see if they look her up. Anderson said Couch did not appear to have any sympathy after killing the victims: "I said then, we’re not through with Ethan Couch—he’s not the kind of person who rehabilitates, who learns his lesson." Couch missed a probation meeting after a video surfaced that appeared to show him drinking alcohol, and authorities have been looking for him ever since. Anderson said Couch was prohibited from drinking as part of his probation, and likely wanted to escape the jail time he could have faced over the video. Couch's mother is divorced from his father, and authorities say Couch's father has been cooperating with investigators and told them he hadn't heard from his son or his ex, who lived together, in about two weeks. Investigators say they are looking into "hundreds and hundreds" of leads. |
Venice, Louisiana (CNN) -- President Obama said Sunday his administration has mounted a "relentless response" to the oil spill unleashed by the sinking of an offshore drill rig in the Gulf of Mexico.
Obama met with local, state and federal officials involved in the cleanup in southeastern Louisiana, the closest stretch of coastline threatened by the massive spill. Afterward, he said that despite "the most advanced technology available," the spill may not be stopped for many days.
"I'm not going to rest, and none of the gentlemen and women who are here are going to rest or be satisfied, until the leak is stopped at the source, the oil on the Gulf is contained and cleaned up and the people of this region are able to go back to their lives and their livelihoods," he said. "We will spare no resource to clean up whatever damage is caused."
Obama met with the commandant of the Coast Guard, Adm. Thad Allen; EPA administrator Lisa Jackson; Louisiana Gov. Bobby Jindal; and the presidents of several parish governments after arriving, White House spokesman Robert Gibbs said. The president's briefing included an update on the procedures being attempted to cap the well and the economic and environmental impact of the spill, Gibbs said.
After landing in New Orleans, Louisiana, on Sunday, Obama joined Jindal on a two-hour drive to Venice, a staging ground for efforts to fight the growing slick.
Appearing on CNN's "State of the Union," Homeland Security Secretary Janet Napolitano, Interior Secretary Ken Salazar and Allen warned that the leaking oil from a rig explosion could continue for weeks with dire consequences.
"It potentially is catastrophic," Salazar said. "I think we have to prepare for the worst."
That would mean oil damaging sensitive coastal wetlands and industries, including a vital fishing sector that was damaged by Hurricane Katrina in 2005.
Obama initially planned to fly over the affected area by helicopter, but weather conditions prevented the flight. Before his trip, Cabinet officials warned he would find a dire situation.
Officials warn of possible catastrophe
Salazar blamed the explosion that caused the spill on a failure in rig technology intended to prevent so-called blowouts.
"There is no doubt at all here that what has happened is the blowout prevention mechanism at the bottom of the well ... is defective," Salazar said. "While there have been blowouts in the past, we have never seen anything that has been quite of this magnitude."
The well is owned by oil company BP. Lamar McKay, president of BP America, told ABC's "This Week" that the company doesn't know why the blowout preventer failed.
All three officials interviewed by CNN repeatedly emphasized that BP is legally responsible for spill and clean-up efforts. They avoided direct criticism of the company, but said BP must do more to try to cap the gushing well.
Allen called the spill "one of the most complex things we've ever dealt with," and said it was impossible so far to predict how much oil will eventually leak.
"If we lost a total well head, it could be 100,000 barrels or more a day," he said.
BP said two Louisiana communities, Venice and Port Fourchon, will likely be the first places hit by the oil slick. Nearly 1 million feet of booms have been deployed in an effort to protect precious estuaries and wildlife, even as thousands of barrels of crude oil continued gushing into the water. Drilling new wells to stop the flow would take a month or two, and it was unclear if the leak could be contained or slowed before then.
WDSU: Rush to save Lake Pontchartrain
McKay said the company is building a containment system to prevent the leaking oil from spreading, but it may take another six to eight days to deploy it. Meanwhile, the company is working to battle the slick offshore and to clean up any oil that reaches the coast.
"We're still working hard, still working hard on the blowout preventer and see if we can actuate this piece of evidently failed equipment," he said. But he compared that to "doing open-heart surgery at 5,000 feet in the dark with robot-controlled submarines."
Sen. Mary Landrieu and Rep. Charlie Melancon, both of Louisiana, said they want the government to put more pressure on BP to find a solution.
"Our government needs to get somewhere between 'drill, baby, drill' and 'spill, baby, spill,' " Melancon said on CBS' "Face the Nation." Landrieu told the same program that the government should force BP to immediately start drilling remedial wells at the site "and hope that one can fix this."
The slick has already taken a toll on life along the Gulf Coast, bringing fishing and tourism to a halt in many places and threatening to cripple those industries for weeks to come.
"I'm pretty much on pause right now. ... It's just a big waiting game," said David Boola, a fisherman who operates boat trips for tourists out of Venice.
WDSU: Oil spill causes empty shrimp nets
Allen noted BP was deploying its top technology such as the remote operation vehicles, which the government doesn't have.
At the same time, Napolitano and Salazar said the Obama administration had reacted quickly to what they called an escalating situation.
Napolitano noted the incident was first an explosion and fire, with a search-and-rescue effort for missing rig workers. It then worsened when the rig sank two days later, followed by the increasing oil leak, she said.
While BP was the first responder, the Coast Guard reacted right away to the situation and deployed 70 vessels and 1 million feet of boom for possible service, Napolitano said.
Salazar noted that the Obama administration has ordered inspections of "blowout preventers" on other Gulf rigs. The government's job was to "keep the boot on the neck" of BP to ensure it meets its obligations in stopping the spill, dealing with the oil slick and paying for all costs and damages.
Also on the CNN program Sunday, Florida's Republican Senate candidate Marco Rubio called the oil slick a "crisis" but withheld judgment on the administration's response. According to Rubio, it appeared that much of the early information provided to the federal government by BP had been "either inaccurate or shortcoming."
In recent days, Rubio said, "We've seen the administration move aggressively, and I hope aggressively enough."
BP partnered with government officials to hold town hall meetings throughout the region Saturday to respond to concerns about the spill's consequences. But Louisiana Gov. Bobby Jindal suggested the response to the oil slick has so far been inadequate.
"We continue to be concerned with BP's ability to respond to this incident," he said.
Environmentalist Richard Charter of the Defenders of Wildlife organization said the oil leak could cause damage that would last decades.
"This event is a self-feeding fire," Charter said. "It is so big and expanding so fast that it's pretty much beyond human response that can be effective.
"You're looking at a long-term poisoning of the area," he said. "Ultimately, this will have a multidecade impact."
The oil spill started April 20, after an explosion on the BP contractor Transocean Ltd.'s Deepwater Horizon drilling platform. Eleven oil-rig workers remain missing and are presumed dead.
The rig sank April 22 about 50 miles off the southeast coast of Louisiana, and the untapped wellhead is gushing oil into the Gulf of Mexico. About 1.6 million gallons of oil have spilled since the explosion, the Coast Guard said Saturday. ||||| Update: Oil slicked federal waters closed to fishermen Oil expected to reach Florida coast in 3 days Next Page 1
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| 3 Previous Page Update 2:11 p.m. The National Oceanographic and Atmospheric Administration is restricting fishing in federal waters most affected by the oil spill, primarily between Louisiana state waters near the mouth of the Mississippi River to waters off of Florida's Pensacola Bay, for a minimum of 10 days according to a press release on deepwaterhorizonresponse.com. The closure is effective immediately and detailed information can be found at sero.nmfs.noaa.gov. Related Oil Spill May 1 Fishermen who wish to file a claim in regards to loss of money or livelihood, damage to boats and more can contact BP at (800) 440-0858. The Coast Guard may also be able to provide assistance and can be reached at 800-280-7118.
“NOAA scientists are on the ground in the area of the oil spill taking water and seafood samples in an effort to ensure the safety of the seafood and fishing activities,” said Dr. Jane Lubchenco, NOAA Administrator, who met with more than 100 fishermen in Louisiana's Plaquemines Parish on Friday night. “Balancing economic and health concerns, this order closes just those areas that are affected by oil. There should be no health risk in seafood currently in the marketplace.” “We stand with America's fisherman, their families and businesses in impacted coastal communities during this very challenging time. Fishing is vital to our economy and our quality of life and we will work tirelessly protect to it," said Secretary of Commerce Gary Locke. NOAA is a bureau of the U.S. Department of Commerce. According to NOAA, there are 3.2 million recreational fishermen in the Gulf of Mexico region who took 24 million fishing trips in 2008. Commercial fishermen in the Gulf harvested more than 1 billion pounds of fin fish and shellfish in 2008. BP will be hiring fishermen to help clean up from the spill. Interested fishermen should call (425) 745-8017. Earlier story Residents in Wakulla County are preparing for the possibility that the Deepwater Horizon oil spill will soon reach Big Bend beaches. One group of volunteers is planning to clean beaches of litter and debris today, which they say will get the beaches in better shape in case the spill comes their way. Another group is preparing for the possibility that they'll have to clean, treat and care for any affected animals.
(2 of 3) Meanwhile, Gov. Charlie Crist has been told that oil from the massive spill off the coast of Louisiana won't reach Florida beaches for at least three days.
But Crist was also told that it's only a matter of time until oil washes up on the Panhandle's sugar-white sands and beyond. Crist was briefed on the spill Saturday by the U.S. Coast Guard, BP PLC and Florida environmental Secretary Michael Sole. He also was shown equipment that's ready to try to contain the oil. Crist said, "We're going to see oil. I wish we weren't, but I think we're going to see it." Related Oil Spill May 1 Florida emergency-management officials said it's possible because of unpredictable weather and other conditions that some coastal areas could see an oily residue in coming days. Trajectories released Saturday from the National Oceanic and Atmospheric Administration go out only three days. The State Emergency Operations Center in Tallahassee was partially activated Saturday, and Bay, Escambia, Gulf, Okaloosa, Santa Rosa and Walton counties remained under a state of emergency. State representatives were at the Unified Command at the U.S. Coast Guard's Sector Mobile in Alabama, and Crist visited staging areas in Pensacola. State agencies were conducting pre-impact assessments, including samplings of water, fish, shellfish and habitats along the Florida coast. "We are ready to respond as necessary," said Lauren McKeague, spokeswoman for the Florida Division of Emergency Management. In Wakulla County, veterinarian Dr. Norm Griggs is heading up an effort to ready supplies, staging areas and volunteers, said Sue Damon, a Shell Point resident. Organizers are looking for empty coastal businesses where volunteers would be able to clean animals affected by the oil spill. "I just can't even imagine the magnitude of this," she said. "We are preparing ourselves for the worst-case scenario." The organization is on Facebook under "Help Prepare for Florida Oil Spill in Panhandle." Other volunteers are gathering 2 p.m. today at Wakulla County High School, 3237 Coastal Highway, Crawfordville. They're planning to clean beaches of trash and debris before any possible arrival of the oil spill.
(3 of 3) "Some of the experts have suggested that we pick up some of the man-made debris that could absorb oil," said Scott Nelson, emergency management director for Wakulla County. "Right now, it's not eminent, but we're trying to be proactive."
Franklin County Emergency Management officials said they were monitoring the spill, too, and taking part in daily conference calls with other officials statewide. The Coast Guard earlier estimated that about 200,000 gallons of oil are spewing out each day — which would mean 1.6 million gallons of oil have spilled since the April 20 explosion that killed 11 workers. However, Coast Guard officials later said it's impossible to know exactly how much oil is leaking. One expert cautioned that if the spill continues growing unchecked, sea currents could suck the sheen down past the Florida Keys and then up the Eastern Seaboard. The environmental mess could eclipse the Exxon Valdez disaster, when an oil tanker spilled 11 million gallons off Alaska's shores in 1989. Related Oil Spill May 1 Next Page 1
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| 3 Previous Page ||||| President Barack Obama, on a trip to Venice, Louisiana, the site of intense response efforts to the recent oil spill in the Gulf of Mexico , promised "an all-hands on deck" response to a "massive and possibly unprecedented environmental disaster."
"I want to emphasize that from day one, we have prepared and planned for the worst while hoping for the best," the president said.
Obama reiterated that it is BP's responsibility to pay for the cleanup: "BP is responsible for this leak. BP will be paying the bill. But as president of the United States, I will spare no effort until this spill is cleaned up."
The president spoke outside the U.S. Coast Guard station in Venice just miles from the approaching oil spill. As rain fell, he said, "I was told it was drizzling. Is this a Louisiana drizzle?"
Obama received a briefing from Adm. Thad Allen, the retiring U.S. Coast Guard commandant who Saturday was appointed to oversee the cleanup response to the April 20 Deepwater Horizon rig explosion.
Allen told Obama where booms had been placed to protect the shoreline and said the Mississippi River's current is acting as a buffer in the delta to block oil from flowing west of the river.
The president had also received a briefing on the oil spill aboard Air Force One on his way to Louisiana. Obama arrived in Venice about 2:30 p.m. in a motorcade with about three dozen people, including his chief of staff, Rahm Emmanuel, Louisiana Gov. Bobby Jindal and Lt. Gov. Mitch Landrieu, who will be sworn in as the mayor of New Orleans on Monday.
The president landed at Louis Armstrong Airport at 12:30 p.m. and had to scrap plans to take a helicopter to Venice because of low cloud cover.
White House spokesman Robert Gibbs said, "It is a serious situation. I wouldn't characterize it necessarily as a worsening situation but as a continuing very serious situation with a lot of oil leaking."
| – President Obama visited Louisiana this afternoon, seeing for himself the effects of the continuing oil spill and promising an "all-hands-on-deck" reaction, the Times-Picayune reports. "BP is responsible for this leak. BP will be paying the bill," he said. "But as president of the United States, I will spare no effort until this spill is cleaned up." Gov. Bobby Jindal met Air Force One at Louis Armstrong airport near New Orleans, and they drove 2 hours to the coast. Poor weather prevented the president and his entourage from taking a helicopter tour of the region, where waves of oil are washing ashore, reports CNN. Federally regulated fishing grounds from Louisiana to Florida have been closed and will remain off-limits for at least 10 days, reports the Tallahassee Democrat. |
seasonal influenza transmission varies throughout the world with time of year and region.1 the mechanisms behind influenza seasonality are not well understood ; however , multiple factors , including virological , immunological , environmental , and social factors likely contribute to the observed seasonal patterns of influenza transmission.2 , 3 these factors give rise to annual influenza epidemics during the winter months in northern and southern hemisphere temperate climates.4 in tropical and subtropical climates , influenza activity may be detected throughout the year , although there is increasing evidence of a notable seasonal component to influenza activity in some tropical countries.3 , 5
pandemic influenza viruses can emerge at any time of year , but it is not clear whether the factors that drive yearly seasonal influenza transmission influence transmission of a novel virus to which the population has little immunity ( resulting in increased population susceptibility , higher attack rates , and prolonged viral shedding in comparison with seasonal influenza ) . it has been postulated that there were seasonal variations in the transmission of pandemic influenza viruses during the 20th century , as they appeared to have had either a secondary or a tertiary wave of activity at the time of the historical influenza season.6 , 7 the a(h1n1)pdm09 pandemic of 20092010 also demonstrated a seasonal component to transmission early during the pandemic , in the americas.8 for example , surveillance during april to august 2009 pointed to higher rates of a(h1n1)pdm09 infection in southern hemisphere temperate countries , where the pandemic began at the time that seasonal influenza activity was expected.5 , 9 , 10
the a(h1n1)pdm09 pandemic provides a unique opportunity to study pandemic influenza transmission dynamics because there were more surveillance data from tropical and subtropical countries obtained during this pandemic than from any previous time in history.11 the objectives of our study are to describe the transmission patterns of the a(h1n1)pdm09 virus throughout the world and to identify whether they varied in relation to geography ( i.e. , latitude and climatic regions ) and time of year when a(h1n1)pdm09 was first detected in relation to countries ' historical influenza season
. this knowledge could be useful for pandemic preparedness , as it might help identify the best timing for the implementation of public health interventions or the distribution of limited supplies during a pandemic .
we compiled laboratoryconfirmed influenza virological reports for the influenza a subtypes h3n2 , seasonal h1n1 , and a(h1n1)pdm09 from recognized sovereign states and other administrative regions ( i.e. , entities not formally recognized as sovereign states such as new caledonia ) around the world ( all referred to as
the study period included the 62 weeks from june 11 , 2009 , to august 10 , 2010 , coinciding with the official start and end date of the pandemic period , as stated by the world health organization ( who ) .
our data sources included virological influenza data obtained by who in flunet11 as well as regional and national laboratory surveillance web sites ( e.g. , http://www.euroflu.org , http://www.nicd.ac.za/ ) .
we analyzed influenza virological data from countries that reported laboratoryconfirmed influenza results for 70% of weeks in the study period and that reported > 120 positive a(h1n1)pdm09 samples during the study period .
we obtained 2010 world population projections and population density by country.12 in addition , we categorized countries by income groups according to world bank classifications ( high income , uppermiddle income , lowermiddle income and low income)13 to identify whether income groups were equally represented in our study ( trend test ) .
we examined each country 's influenza virological data by calculating the proportion of a(h1n1)pdm09positive specimens identified each week , out of all a(h1n1)pdm09positive samples tested during the study period ( weekly proportion ) .
we then graphed the weekly proportions for each country to help us visualize the countries ' influenza activity .
we used locally weighted scatterplot smoothing ( loess ) to create smoothed curves of influenza activity for each country ( figure 1 ) . using the smoothed data , we determined the following parameters of a(h1n1)pdm09 activity for each country : week of first detection of the a(h1n1)pdm09 virus , the proportion of a(h1n1)pdm09 specimens detected during the week of highest activity ( peak activity ) , number of weeks from first a(h1n1)pdm09 detection until the week of peak activity ( time to peak ) , number of weeks when 90% of a(h1n1)pdm09 specimens were detected ( i.e. , time encompassing the 5th and 95th percentiles of cumulative a(h1n1)pdm09 weekly proportion ) , and number of waves of a(h1n1)pdm09 activity during the study period . we defined a wave as the time period including an increase and subsequent decrease in a(h1n1)pdm09 activity and including a peak week of activity .
a peak week was defined as a week during which the loesssmoothed proportion of a(h1n1)pdm09 activity was higher than the week immediately preceding it and immediately following it , and when the weekly proportion was at least 1% higher than in the troughs on either side .
costa rica showed only one wave of pandemic activity ( figure 1 ) ; the proportion of a(h1n1)pdm09positive specimens identified during the peak week ( week 27 ) was 67% , and it was 05% during the trough week that followed ( week 43 ) .
the smaller increases observed later in the study period did not meet the peak definition .
this method helped us to avoid counting spurious fluctuations as peaks and was selected after evaluating a range of thresholds .
examples of the weekly proportion of influenza a(h1n1)pdm09positive specimens using locally weighted scatterplot smoothing technique in three selected countries .
countries were then classified into climatic regions by using their central latitude ( i.e. , the latitude at the center of the country ) : northern and southern temperate ( central latitude |30| ) , subtropical ( central latitude |235299| and tropical ( central latitude |234|).14 we also classified countries into two other categories : those where a(h1n1)pdm09 was first detected during the start of the country 's historical influenza season and those where a(h1n1)pdm09 was detected at any other time .
the start of the historical influenza season was defined as the time encompassing the 6 weeks before the start of the influenza season and the first half of the season .
the timing of country 's historical influenza season ( i.e. , typical month of start and end of the season ) was only known for a subgroup of countries ( 17 in temperate regions and 22 in tropical
subtropical regions ) based on data from a prior study.15 in the case of china , data from mainland temperate and subtropical regions , chinese taipei and hong kong sar , were analyzed separately .
we quantified the number of weeks between initial detection of a(h1n1)pdm09 in mexico and the united states ( third week in april 2009 ) and the first report of a(h1n1)pdm09 in every country .
we then calculated the median number of weeks of first a(h1n1)pdm09 detection for each continent .
we compared the parameters of a(h1n1)pdm09 activity described above ( peak activity , time to peak , number of weeks between the 5 and 95th percentiles of cumulative a(h1n1)pdm09 weekly proportion , and number of waves ) between countries in temperate and tropical subtropical climatic regions .
we also compared the same parameters of a(h1n1)pdm09 activity between countries where a(h1n1)pdm09 was first detected during the start of countries ' historical influenza season and those where a(h1n1)pdm09 was introduced at any other time of the year .
this was made for the subgroup of 39 countries for which we had data on the timing of the historical influenza season , as described above .
in addition , we explored whether there was a correlation between the following variables : peak activity and the proportion of cases within the 12week period around the peak ; latitude and peak activity ; latitude and number of weeks from detection of a(h1n1)pdm09 to countries ' peak week ; latitude and the proportion of total a(h1n1)pdm09positive specimens out of total influenza apositive specimens during the pandemic .
lastly , we calculated the minimum doubling time of a(h1n1)pdm09 in each country using the following formula : doubling time = ln(2)/ln(weekly proportion of a(h1n1)pdm09/proportion in the previous week ) .
we compared the mean doubling time in northern hemisphere temperate , southern hemisphere temperate , and tropical subtropical countries .
we used sas 9.2 ( sas institute inc . , cary , nc , usa ) to conduct wilcoxon rank sum tests and kruskal wallis tests to compare continuous data , chisquare tests to compare categorical data , spearman 's test to identify correlations , and cochran armitage test to identify trends .
eighty of these countries provided sufficient laboratoryconfirmed influenza data to meet our inclusion criteria and were included in our analyses ( figure 2 ) ( table s1 ) .
the 80 countries have a cumulative population of 55 billion persons or 80% of the world 's population . among these 80 countries ,
47 ( 59% ) were classified as temperate ( 45 from the northern hemisphere and two from the southern hemisphere ) and 33 ( 41% ) were tropical subtropical . as there were only five subtropical countries , we grouped them with the tropical countries for all analyses . among 213 countries
that had been classified by the world bank into income group classifications , our sample countries included 31 ( 45% ) of 69 highincome countries , 21 ( 44% ) of 48 uppermiddleincome countries , 17 ( 30% ) of 56 lowermiddleincome countries , and 8 ( 20% ) of 40 lowincomecountries
map of the world highlighting the countries included in our analyses and the number of weeks from the time of first world detection of influenza a(h1n1)pdm09 ( third week of april , 2009 ) , until the median week of detection in each continent .
the median number of weeks from first detection of a(h1n1)pdm09 in mexico and the united states ( third week in april 2009 ) until first detection in countries from each continent was 2 weeks ( range 020 ) in north / central america , 3 weeks ( range 015 ) in south america , six weeks ( range 221 ) in europe , 8 weeks ( range 510 ) in oceania , 9 weeks ( range 240 ) in asia , and 16 weeks ( range 725 ) in africa ( p < 001 ) ( figure 2 ) .
the median proportion of a(h1n1)pdm09 specimens detected during the peak week ( peak activity ) was significantly higher in temperate ( 012 ) than in tropical subtropical ( 009 ) regions ( p < 001 ) ( table 1 ) .
we found fewer median number of weeks between the 5th and 95th percentiles of the a(h1n1)pdm09 weekly proportion in temperate countries ( 20 weeks [ 1324 interquartile range ( iqr ) ] ) than in tropical
we also identified a positive correlation between peak activity and the proportion of cases within the 12week period around the peak ( r
s = 079 , p < 001 ) ( figure 3a ) .
the median number of weeks from first detection of a(h1n1)pdm09 to peak week was 25 weeks ( 2027 iqr ) in temperate and 9 weeks ( 616 iqr ) in tropical subtropical countries ( p < 001 ) , consistent with a positive correlation between country latitude and number of weeks from country detection of a(h1n1)pdm09 to country peak week ( r
s = 046 , p < 001 ) ( figure 3b ) . parameters of influenza a(h1n1)pdm09 activity by climatic region wilcoxon rank sum tests and kruskal wallis tests
correlation between countries ' influenza a(h1n1)pdm09 weekly proportion in the peak week ( peak activity ) and the proportion of cases within the 12week period around the peak ( a ) . correlation between country latitude and number of weeks from country detection of influenza a(h1n1)pdm09 until countries ' peak week ( b ) .
correlation between countries ' central latitude and the proportion of influenza a(h1n1)pdm09positive specimens , out of all influenza apositive specimens ( d ) . in 44 ( 98% )
of 45 northern hemisphere temperate countries , the peak week occurred within the 12 weeks from the 2nd week of october to the 4th week of december 2009 , a time corresponding to the autumn winter period in the region ( figure 4 ) .
this time typically also corresponds to the early part of the countries ' historical influenza season .
the peak week of the two southern hemisphere temperate countries also clustered within their autumn winter period
. however , among the tropical countries , the peak week occurred over a period of 47 weeks , extending from the 3rd week of may 2009 to the 4th week of march 2010 .
there were 26 countries with more than one wave of activity , but there was no significant difference in the number of waves , by climatic region ( table 1 ) .
the mean a(h1n1)pdm09 minimum doubling time was not significantly different in northern hemisphere temperate ( 63 days [ 26 sd ] ) , southern hemisphere temperate ( 57 days [ 15 sd ] ) , and tropical subtropical countries ( 62 days [ 23 sd ] ) ( p = 04 ) ( figure 3c ) .
time course of the peak influenza a(h1n1)pdm09 weekly proportion ( peak week ) by country and climatic region .
the black bars represent the peak week of h1n1pdm09 virus activity for each country during the pandemic .
we found a positive correlation between countries ' central latitude and countries ' proportion of total a(h1n1)pdm09positive specimens out of total influenza apositive samples for the pandemic period ( r
s = 076 , p < 001 ) ( figure 3d ) .
we had data on the timing of the historical influenza season for a subgroup of 39 countries .
the median number of weeks from first a(h1n1)pdm09 detection until peak week was 8 weeks ( 613 iqr ) in countries where a(h1n1)pdm09 was first identified during the start of their historical influenza season .
the median number of weeks from first detection until peak week was 25 weeks ( 2027 iqr ) in countries where first detection occurred at any other time of the year ( p < 001 ) .
three of 14 ( 21% ) countries had more than one wave of a(h1n1)pdm09 where a(h1n1)pdm09 was introduced during the start of the historical influenza season , compared with 12 of 25 countries ( 48% ) where it was introduced during any other time , although this difference was not statistically significant ( p = 017 ) .
there was no statistically significant association between peak activity and the median number of weeks between the 5th and 95th percentiles of a(h1n1)pdm09 weekly proportion , among countries where a(h1n1)pdm09 was introduced during the start of the historical influenza season compared with countries where it was introduced at any other time of the year ( table 2 ) .
parameters of influenza a(h1n1)pdm09 activity in countries where influenza a(h1n1)pdm09 was first detected during the start of countries ' historical influenza season and countries where it was first detected at a different time of the year wilcoxon rank sum tests and kruskal wallis tests were used to compare continuous data , chisquare tests to compare categorical data .
eighty of these countries provided sufficient laboratoryconfirmed influenza data to meet our inclusion criteria and were included in our analyses ( figure 2 ) ( table s1 ) .
the 80 countries have a cumulative population of 55 billion persons or 80% of the world 's population . among these 80 countries ,
47 ( 59% ) were classified as temperate ( 45 from the northern hemisphere and two from the southern hemisphere ) and 33 ( 41% ) were tropical subtropical . as there were only five subtropical countries , we grouped them with the tropical countries for all analyses . among 213 countries
that had been classified by the world bank into income group classifications , our sample countries included 31 ( 45% ) of 69 highincome countries , 21 ( 44% ) of 48 uppermiddleincome countries , 17 ( 30% ) of 56 lowermiddleincome countries , and 8 ( 20% ) of 40 lowincomecountries
map of the world highlighting the countries included in our analyses and the number of weeks from the time of first world detection of influenza a(h1n1)pdm09 ( third week of april , 2009 ) , until the median week of detection in each continent . the median number of weeks from first detection of a(h1n1)pdm09 in mexico and the united states ( third week in april 2009 ) until first detection in countries from each continent was 2 weeks ( range 020 ) in north / central america , 3 weeks ( range 015 ) in south america , six weeks ( range 221 ) in europe , 8 weeks ( range 510 ) in oceania , 9 weeks ( range 240 ) in asia , and 16 weeks ( range 725 ) in africa ( p < 001 ) ( figure 2 ) .
the median proportion of a(h1n1)pdm09 specimens detected during the peak week ( peak activity ) was significantly higher in temperate ( 012 ) than in tropical subtropical ( 009 ) regions ( p < 001 ) ( table 1 ) .
we found fewer median number of weeks between the 5th and 95th percentiles of the a(h1n1)pdm09 weekly proportion in temperate countries ( 20 weeks [ 1324 interquartile range ( iqr ) ] ) than in tropical subtropical countries ( 27 weeks [ 1744 iqr ] , p < 001 ) ( table 1 ) .
we also identified a positive correlation between peak activity and the proportion of cases within the 12week period around the peak ( r
s = 079 , p <
the median number of weeks from first detection of a(h1n1)pdm09 to peak week was 25 weeks ( 2027 iqr ) in temperate and 9 weeks ( 616 iqr ) in tropical subtropical countries ( p < 001 ) , consistent with a positive correlation between country latitude and number of weeks from country detection of a(h1n1)pdm09 to country peak week ( r
s = 046 , p < 001 ) ( figure 3b ) .
parameters of influenza a(h1n1)pdm09 activity by climatic region wilcoxon rank sum tests and kruskal wallis tests were used to compare continuous data , chisquare tests to compare categorical data .
correlation between countries ' influenza a(h1n1)pdm09 weekly proportion in the peak week ( peak activity ) and the proportion of cases within the 12week period around the peak ( a ) .
correlation between country latitude and number of weeks from country detection of influenza a(h1n1)pdm09 until countries ' peak week ( b ) .
correlation between countries ' central latitude and the proportion of influenza a(h1n1)pdm09positive specimens , out of all influenza apositive specimens ( d ) . in 44 ( 98% )
of 45 northern hemisphere temperate countries , the peak week occurred within the 12 weeks from the 2nd week of october to the 4th week of december 2009 , a time corresponding to the autumn winter period in the region ( figure 4 ) .
this time typically also corresponds to the early part of the countries ' historical influenza season .
the peak week of the two southern hemisphere temperate countries also clustered within their autumn winter period . however , among the tropical countries , the peak week occurred over a period of 47 weeks , extending from the 3rd week of may 2009 to the 4th week of march 2010 .
there were 26 countries with more than one wave of activity , but there was no significant difference in the number of waves , by climatic region ( table 1 ) .
the mean a(h1n1)pdm09 minimum doubling time was not significantly different in northern hemisphere temperate ( 63 days [ 26 sd ] ) , southern hemisphere temperate ( 57 days [ 15 sd ] ) , and tropical subtropical countries ( 62 days [ 23 sd ] ) ( p = 04 ) ( figure 3c ) .
time course of the peak influenza a(h1n1)pdm09 weekly proportion ( peak week ) by country and climatic region .
the black bars represent the peak week of h1n1pdm09 virus activity for each country during the pandemic .
we found a positive correlation between countries ' central latitude and countries ' proportion of total a(h1n1)pdm09positive specimens out of total influenza apositive samples for the pandemic period ( r
s = 076 , p < 001 ) ( figure 3d ) .
we had data on the timing of the historical influenza season for a subgroup of 39 countries .
the median number of weeks from first a(h1n1)pdm09 detection until peak week was 8 weeks ( 613 iqr ) in countries where a(h1n1)pdm09 was first identified during the start of their historical influenza season .
the median number of weeks from first detection until peak week was 25 weeks ( 2027 iqr ) in countries where first detection occurred at any other time of the year ( p < 001 ) .
three of 14 ( 21% ) countries had more than one wave of a(h1n1)pdm09 where a(h1n1)pdm09 was introduced during the start of the historical influenza season , compared with 12 of 25 countries ( 48% ) where it was introduced during any other time , although this difference was not statistically significant ( p = 017 ) . there was no statistically significant association between peak activity and the median number of weeks between the 5th and 95th percentiles of a(h1n1)pdm09 weekly proportion , among countries where a(h1n1)pdm09 was introduced during the start of the historical influenza season compared with countries where it was introduced at any other time of the year ( table 2 ) .
parameters of influenza a(h1n1)pdm09 activity in countries where influenza a(h1n1)pdm09 was first detected during the start of countries ' historical influenza season and countries where it was first detected at a different time of the year wilcoxon rank sum tests and kruskal wallis tests were used to compare continuous data , chisquare tests to compare categorical data .
during the 20092010 pandemic , a(h1n1)pdm09 activity was associated with latitude ; specifically , our analysis demonstrated that temperate countries had higher intensity ( higher median peak ) but shorter duration of a(h1n1)pdm09 activity ( fewer weeks between the 5th and 95th percentiles ) than tropical subtropical countries .
the positive correlation between peak activity and the proportion of cases within the 12week period around the peak demonstrates that countries with higher peak incidence had more concentrated waves overall .
these findings are consistent with our initial hypothesis , as we anticipated that pandemic influenza would show similar behavior to seasonal influenza viruses and readily transmit , during a shorter time period , in temperate climate countries , and demonstrate less intense activity spread out over a longer period of time in tropical climate countries .
we also demonstrate that in northern and southern hemisphere temperate countries , the peak week of pandemic activity was most frequently identified within a 12week period during their autumn winter season ( the time of year when seasonal influenza is typically circulating ) , while in tropical countries , the timing of the peak was heterogeneously distributed over a 47week period .
these findings may explain why the median number of weeks from first a(h1n1)pdm09 detection until reaching peak week was longer in temperate climate countries , as 45 of 47 temperate countries in our study were in the northern hemisphere , and they were experiencing spring when a(h1n1)pdm09 was introduced ( a time of year when influenza activity is low in these climatic regions ) .
it is also consistent with our finding that countries where a(h1n1)pdm09 was introduced during the start of their historical influenza season had less time until peak a(h1n1)pdm09 activity was reached , and although not statistically significant , these countries also had lower probabilities of having a second wave of pandemic activity . as the timing of the historical influenza season corresponds to the time of year when the environmental , social , or biological factors responsible for influenza seasonality create a setting for enhanced influenza virus transmission,2 ,
3 we suggest that these factors might also have a role in the transmission of novel influenza viruses .
the positive correlation between countries ' central latitudes and their proportion of a(h1n1)pdm09positive specimens out of all influenza apositive specimens maybe the result of the emergence of a(h1n1)pdm09 when little to no seasonal influenza was circulating in northern hemisphere temperate countries ; hence , a(h1n1)pdm09 would comprise a higher proportion of influenza infections .
in contrast , in tropical countries , with more yearround influenza transmission and seasonal influenza circulating , a(h1n1)pdm09 would comprise a lower proportion of infections .
our findings have implications for pandemic preparedness , as they could inform the timing when supplies , services , and public health interventions might be most needed during a pandemic .
the time from first identification of a novel influenza strain until it is detected in every continent can be weeks , and countries that are not in the epicenter of a pandemic should consider using this time to implement early interventions that may help further delay the spread of pandemic viruses , as recommended by who.16 countries in temperate climates might need to plan for the highest levels of activity during the autumn
winter ( despite the fact that some might face an initial wave of activity close to the introduction of the pandemic virus ) ; this is supported by findings from previous pandemics in countries like the united states . , where peaks of activity occurred during the autumn / winter months.6 , 7 , 17 countries in tropical climates can expect influenza activity to be spread out over a longer period of time , with no evident pattern in the timing of their peak activity .
other investigators have made efforts to use influenza information obtained through current surveillance systems along with morbidity and mortality data from previous pandemics to generate models that may help estimate the burden of a future pandemic.18 there were also several contributions from mathematical modeling during the a(h1n1)pdm09 pandemic.19 some models have even looked at the role of seasonality in previous pandemics as well as the potential role in future pandemics.20 our findings suggest the potential utility of accounting for latitude and historical timing of the influenza season when modeling the behavior of pandemic viruses .
although we analyzed data from 80 countries containing approximately 80% of the world 's population , these data might not be representative of all regions within each country , and our data may not be globally representative .
this is especially true of lowerincome countries , as these were underrepresented in comparison with higherincome countries .
the number of samples tested , laboratory methods used , sampling criteria , and reporting practices varied by country which might limit the comparability of data between countries .
timing of the historical influenza season was known for less than half of the countries in this study .
we were unable to compare the absolute incidence of a(h1n1)2009 between countries , as data available to us did not include rates of illness .
the transmission of pandemic influenza a(h1n1)2009 exhibited important similarities with the transmission of seasonal influenza , despite the fact that it was a novel virus to which the majority of the population had little preexisting immunity . in comparison with tropical and subtropical countries , we found that countries in temperate climates had higher peaks , shorter durations of pandemic activity , and higher proportions of a(h1n1)pdm09 among influenza apositive samples .
the time of year likely played a role in temperate climate countries , as the peak of pandemic activity occurred during the fall
the opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the centers for disease control and prevention or the institutions with which the authors are affiliated .
table s1 . countries included in analyses along with their central latitude and climatic region . | backgroundseasonal influenza activity varies with geography and time of year.objectiveto describe how pandemic influenza a(h1n1)2009 [ a(h1n1)pdm09 ] activity varied during the 20092010 pandemic.methodswe analyzed influenza virological data compiled by the world health organization from june 2009august 2010 .
we calculated weekly proportions of a(h1n1)pdm09positive specimens out of all a(h1n1)pdm09positive specimens detected during the study period for each country .
we compared parameters of pandemic activity ( e.g. , peak a[h1n1]pdm09 weekly proportion [ peak activity ] , number of weeks between the 5th and 95th percentiles of a(h1n1)pdm09 cumulative weekly proportion [ duration of activity ] ) between countries in temperate and tropical subtropical regions .
we quantified the proportion of a(h1n1)pdm09 out of all influenza a specimens by country and correlated it with countries ' central latitudes.resultswe analyzed data from 80 countries ( 47 temperate , 33 tropical
subtropical ) .
the median proportion of cases identified during the peak week was higher in temperate ( 012 ) than in tropical subtropical ( 009 ) regions ( p < 001 ) .
the median duration of activity was longer in tropical
subtropical ( 27 weeks ) than in temperate countries ( 20 weeks ) ( p < 001 ) . in most temperate countries ( 98% ) , peak pandemic activity occurred during the fall
winter period .
there was a positive correlation between country central latitude and proportion of a(h1n1)pdm09 out of all influenza a specimens ( r : 076 ; p < 001).conclusionsthe transmission of a(h1n1)pdm09 exhibited similarities with seasonal influenza transmission in that activity varied between temperate and tropical subtropical countries and by time of year .
our findings suggest the potential utility of accounting for these factors during future pandemic planning . |
ancient indian literature comprises a remarkably broad definition of medicinal plants and considers all plant parts to be potential sources of medicinal substances . however , a key obstacle which has hindered the acceptance of the alternative medicines in the developed countries is the lack of documentation and rigorous quality control .
there is a need for documentation of research work carried out on traditional medicines . with this backdrop
, it becomes extremely important to make an effort toward standardization of the plant - based medicines .
administration of drug in various dosage forms provides an opportunity to the physician to choose better options .
kwatha preparations are one among the panchavidha kashaya kalpana which are highly effective , but they are to be used when freshly prepared and they are often overlooked due to the preparation method and palatability . in the present study , dashanga kwatha , a known formulation used in urdhwaga amlapitta ( non - ulcer dyspepsia ) , was converted into tablet form by rasakriya method to increase the shelf life , make it palatable , easy to dispense , for dose fixation , etc . with the intention of standardization and quality control of the plant - based drugs ,
the crude drugs mentioned in chakradutta in amlapitta rogadhikara for the preparation of dashanga kwatha were taken from the pharmacy of ipgt and ra , gujarat ayurved university , jamnagar , after proper authentication by the department of pharmacognosy of the institute .
then , the physical impurities were removed and the drugs were washed with water , sorted and sun dried below 45c . dried drugs were stored in tightly closed containers .
the crude drugs used in dashanga kwatha with their botanical identities and parts used are given in table 1 .
crude drugs of dashanga kwatha the authenticated crude drugs were crushed to a coarse powder separately and then mixed thoroughly with 8 parts of water in a stainless steel container and then continuous mild heat was applied until it was reduced to one - fourth of its initial quantity . during the heating process , continuous
stirring was done to facilitate the evaporation and avoid any deterioration due to burning of materials . after a desirable reduction in volume
was achieved , the kwatha was filtered through single folded cotton cloth and collected in a separate vessel .
then , the kwatha was boiled again over slow fire on a gas stove , maintaining the temperature between 90c and 95c till a semisolid consistency is obtained . as the water evaporates , the viscosity of the extract increases , resulting in ghana form .
then , the ghana was mixed with the churna of dashanga ( up to 10% of extract ) further forming a solid mass .
16 sieve and granules were prepared and then dried at 50c in a hot air oven for 10 hours .
the formulation was then compressed in a single - punch tablet press with a target weight of 250 mg .
dashanga kwatha and dashanga kwatha ghana tablet were subjected to various analytical parameters as follows .
organoleptic parameters : rupa ( color ) , rasa ( taste ) , gandha ( odor ) and sparsha ( touch)physico - chemical parameters : ph of 5% aqueous soln . ,
loss on drying at 110c , ash value , acid insoluble ash , water soluble extractive , methanol soluble extractivequantitative tests for tablet : weight variation test , tablet hardness test , tablet disintegration time , friabilityqualitative tests for various functional groups : tannins , mucilages , sterols / terpenoids , ascorbic acid , alkaloids , saponins , starch , flavonoids , glycosides and carbohydrateschromatographic analysis : high performance thin layer chromatographic ( hptlc)test solution : methanol extract of dashanga kwatha ghana tablets.stationary phase : silica gel gf254toluene : ethyl acetate ( 8:1.5 v / v ) was selected as the solvent system through trial and error method . the developed plate was visualized under visible day light , short uv ( 254 nm ) , long uv ( 366 nm ) .
the rf values were recorded.toxicological : heavy metal analysis , pesticide residue valuemicrobial overload : bacterial and fungal growth study was carried outreagents and chemicals : all the reagents and chemicals used for the study were of analytical grade .
organoleptic parameters : rupa ( color ) , rasa ( taste ) , gandha ( odor ) and sparsha ( touch ) physico - chemical parameters : ph of 5% aqueous soln . ,
loss on drying at 110c , ash value , acid insoluble ash , water soluble extractive , methanol soluble extractive quantitative tests for tablet : weight variation test , tablet hardness test , tablet disintegration time , friability qualitative tests for various functional groups : tannins , mucilages , sterols / terpenoids , ascorbic acid , alkaloids , saponins , starch , flavonoids , glycosides and carbohydrates chromatographic analysis : high performance thin layer chromatographic ( hptlc ) test solution : methanol extract of dashanga kwatha ghana tablets .
stationary phase : silica gel gf254 toluene : ethyl acetate ( 8:1.5 v / v ) was selected as the solvent system through trial and error method .
the developed plate was visualized under visible day light , short uv ( 254 nm ) , long uv ( 366 nm ) .
toxicological : heavy metal analysis , pesticide residue value microbial overload : bacterial and fungal growth study was carried out reagents and chemicals : all the reagents and chemicals used for the study were of analytical grade .
the crude drugs mentioned in chakradutta in amlapitta rogadhikara for the preparation of dashanga kwatha were taken from the pharmacy of ipgt and ra , gujarat ayurved university , jamnagar , after proper authentication by the department of pharmacognosy of the institute .
then , the physical impurities were removed and the drugs were washed with water , sorted and sun dried below 45c . dried drugs were stored in tightly closed containers .
the crude drugs used in dashanga kwatha with their botanical identities and parts used are given in table 1 .
the authenticated crude drugs were crushed to a coarse powder separately and then mixed thoroughly with 8 parts of water in a stainless steel container and then continuous mild heat was applied until it was reduced to one - fourth of its initial quantity . during the heating process , continuous
stirring was done to facilitate the evaporation and avoid any deterioration due to burning of materials . after a desirable reduction in volume
was achieved , the kwatha was filtered through single folded cotton cloth and collected in a separate vessel . then , the kwatha was boiled again over slow fire on a gas stove , maintaining the temperature between 90c and 95c till a semisolid consistency is obtained . as the water evaporates , the viscosity of the extract increases , resulting in ghana form .
then , the ghana was mixed with the churna of dashanga ( up to 10% of extract ) further forming a solid mass .
16 sieve and granules were prepared and then dried at 50c in a hot air oven for 10 hours .
the formulation was then compressed in a single - punch tablet press with a target weight of 250 mg .
dashanga kwatha and dashanga kwatha ghana tablet were subjected to various analytical parameters as follows .
organoleptic parameters : rupa ( color ) , rasa ( taste ) , gandha ( odor ) and sparsha ( touch)physico - chemical parameters : ph of 5% aqueous soln . ,
loss on drying at 110c , ash value , acid insoluble ash , water soluble extractive , methanol soluble extractivequantitative tests for tablet : weight variation test , tablet hardness test , tablet disintegration time , friabilityqualitative tests for various functional groups : tannins , mucilages , sterols / terpenoids , ascorbic acid , alkaloids , saponins , starch , flavonoids , glycosides and carbohydrateschromatographic analysis : high performance thin layer chromatographic ( hptlc)test solution : methanol extract of dashanga kwatha ghana tablets.stationary phase : silica gel gf254toluene : ethyl acetate ( 8:1.5 v / v ) was selected as the solvent system through trial and error method .
the developed plate was visualized under visible day light , short uv ( 254 nm ) , long uv ( 366 nm ) .
the rf values were recorded.toxicological : heavy metal analysis , pesticide residue valuemicrobial overload : bacterial and fungal growth study was carried outreagents and chemicals : all the reagents and chemicals used for the study were of analytical grade .
organoleptic parameters : rupa ( color ) , rasa ( taste ) , gandha ( odor ) and sparsha ( touch ) physico - chemical parameters : ph of 5% aqueous soln . ,
loss on drying at 110c , ash value , acid insoluble ash , water soluble extractive , methanol soluble extractive quantitative tests for tablet : weight variation test , tablet hardness test , tablet disintegration time , friability qualitative tests for various functional groups : tannins , mucilages , sterols / terpenoids , ascorbic acid , alkaloids , saponins , starch , flavonoids , glycosides and carbohydrates chromatographic analysis : high performance thin layer chromatographic ( hptlc ) test solution : methanol extract of dashanga kwatha ghana tablets .
stationary phase : silica gel gf254 toluene : ethyl acetate ( 8:1.5 v / v ) was selected as the solvent system through trial and error method .
the developed plate was visualized under visible day light , short uv ( 254 nm ) , long uv ( 366 nm ) .
toxicological : heavy metal analysis , pesticide residue value microbial overload : bacterial and fungal growth study was carried out reagents and chemicals : all the reagents and chemicals used for the study were of analytical grade .
comparative organoleptic characters were the following : rupa ( color ) was dark brown , rasa ( taste ) was bitter , gandha ( odor ) was characteristic due to the specific properties of the various ingredients and sparsha ( consistency / texture ) of dashanga kwatha was liquid and dashanga kwatha ghana tablet was smooth as given in table 2 .
organoleptic parameters of dashanga kwatha and tablet ph of the kwatha was 4.53 0.03 and that of tablet was 4.21 0.02 , loss on drying in kwatha was 3.4 0.20% w / w and in tablet was 0.09 0.01% w / w as given in table 3 .
physico - chemical parameters of dashanga kwatha and tablet the average weight of the tablet was 251.23 mg , hardness of tablet was 2.74 0.079 and disintegration time was 33 min and friability was 0.92% as given in table 4 .
quantitative parameters of dashanga kwatha ghana tablet qualitative analysis reveals the presence of tannins , mucilage , ascorbic acid , alkaloids , saponins , glycosides , flavonoids and carbohydrates in the formulation , whereas sterols / terpenoids and starch were absent as given in table 5 . qualitative parameters of dashanga kwatha and dashanga kwatha ghana tablet findings of the analysis of hptlc , heavy metals , pesticide residual value , microbial count and pathogens of dashanga kwatha ghana tablet are shown in tables 610 , respectively .
rf values of hptlc analysis of methanolic extract at long uv ( 366 nm ) rf values of hptlc analysis of methanolic extract at short uv ( 254 nm ) pesticide residual value total microbial count and pathogens
ghana kalpana , a second derivative preparation of kwatha kalpana , is one of the extraction methods in which water soluble material is extracted by kwatha method and reheated till it is converted into concentrated solid form .
the procedure adopted to convert dashanga kwatha ghana into tablet form was wet granulation method of tablet preparation .
gum acacia was added as the binding agent ( 1% ) of the derived ghana , i.e. 70 g in powder form along with the 10% powder of dashanga kwatha .
its addition imparts cohesiveness and ensures that the tablet remains intact after compression as well as imparts desired hardness and size .
however , it has the disadvantage of being variable in its composition based on its natural origin , and it is usually fairly contaminated with bacteria .
drying of granules in hot air oven was carried out at 4550c for 6 hours to reduce microbial proliferation .
since lubrication is basically a coating process , the finer the particle size of the lubricant , the more effective the lubricant is likely to be . with the help of tablet punching machine
the organoleptic parameters form the basic criteria for selecting a raw drug and also to confirm the finished product .
color was brownish , taste was bitter and odor was characteristic due to the specific properties of the various ingredients [ table 2 ] .
the ph conventionally represents the acidity and alkalinity ; ph of the kwatha and tablet showed to be weak acidic in nature .
loss on drying indicates the moisture content ; in the present sample , it was 0.1% .
ash value depends upon the inorganic substances present in the particular drug ; this parameter has importance in quality control and standardization of drugs .
the higher the inorganic substances present in drugs , more will be the ash value . here
, the ash value was 12.0 0.30% which may be due to the extensive heating process involved in preparation of this formulation [ table 3 ] .
soluble principles of the samples were seen in water and methanol ; in water , it was 49.6% and in methanol , it was 40% . in both the media ,
solubility of sample was more as the sample itself which was used to prepare the tablet was derived from water extractive . in the solubility test ,
increase in water soluble extractive was found , which depicts its more bioavailability in water medium [ table 3 ] .
disintegration time was 33 min and friability was not more than 0.92% on an average [ table 4 ] .
physico - chemical analysis of dashanga kwatha ghana tablet was done for the quality control purpose .
qualitative tests are used to detect the presence of functional groups , which play a very important role in the expression of biological activity .
the present study reveals the presence of tannins , mucilage , ascorbic acid , alkaloids , saponins , glycosides , flavonoids and carbohydrates in the formulation , whereas sterols / terpenoids and starch were found to be absent [ table 5 ] .
preliminary hptlc profile of dashanga kwatha ghana tablet has been developed [ figures 13 ] .
this can be considered as the reference standard for validating this formulation in future [ tables 6 and 7 ] .
densitogram of dashanga kwatha ghana tablets ( a 254 nm , b 366 nm ) hptlc profile of dashanga kwatha ghana tablets ( a 254 nm , b
366 nm ) photograph chromplate ( a 254 nm , b 366 nm ) heavy metals were not detected [ table 8 ] , thus showing the purity of the raw drugs and also the finished product .
medicinal plant materials are liable to be affected by pesticide residues which accumulate from agricultural practices of spraying , treating soils during cultivation and through the administration of fumigants during storage .
organophosphorous pesticides were found below the detection limit , which is a clear indication of quality land practices and safe storage of raw drugs [ table 9 ] .
medicinal plant matters normally carry bacteria and moulds often originating in soil in high numbers . in the present formulation ,
the microbial count was within permissible limits [ table 10 ] , which indicates the proper hygiene norms followed during the preparation of formulation and packing .
the study reveals that sufficient quality control parameters were followed during the preparation of formulation .
organoleptic parameters , physicochemical analysis , heavy metal analysis , pesticide residue and microbial overload analysis were carried out as per the norms of who guidelines and the absence of heavy metals , pesticides in raw material and microbes in the finished product indicates the genuineness of final product .
hptlc profile generated in this particular study can be considered as a preliminary tool ascertaining the authenticity of dashanga kwatha ghanavati in the tablet form . | herbal medicines have a long therapeutic history and are still serving many of the health needs of a large population of the world .
however , the quality control and quality assurance still remains a challenge because of the high variability of chemical components involved .
herbal drugs , singularly and in combinations , contain numerous compounds in complex matrices in which no single active constituent is responsible for the overall efficacy .
this creates a challenge in establishing quality control standards and standardization of finished herbal drugs .
many preparations have been mentioned in ayurvedic text books for the treatment of urdhwaga amlapitta ( non - ulcer dyspepsia ) .
dashanga kwatha is one such known formulation . in this study , dashanga kwatha was converted into tablet form to increase the shelf life , make it easy to dispense , for dose fixation , etc .
the dashanga kwatha ghana tablet was subjected to organoleptic analysis , phytochemical analysis , and qualitative analysis to detect the presence of various functional groups , and to high performance thin layer chromatography ( hptlc ) examination by optimizing the solvent systems .
the investigation revealed the presence of tannins , mucilage , ascorbic acid , alkaloids , saponins , glycosides , flavonoids and carbohydrates mainly . |
SECTION 1. ESTABLISHMENT OF COMMISSION.
For the purpose of preserving and interpreting for the educational
and inspirational benefit of present and future generations the unique
and significant contribution to our national heritage of certain
historic and cultural lands, waterways, and edifices in the Great Falls
of the Passaic/S.U.M. National Historic District located in the City of
Paterson, State of New Jersey (Alexander Hamilton's laboratory for the
development of industrial America as well as America's first industrial
city) with emphasis on harnessing this unique urban environment for its
educational value as well as for recreation, there is hereby
established the Great Falls Historic District Commission (hereinafter
referred to as the ``Commission''), the purpose of which shall be to
prepare a plan for the preservation, interpretation, development, and
use, by public and private entities, of the historic, cultural, and
architectural resources of the Great Falls of Passaic/S.U.M. National
Historic District in the City of Paterson, State of New Jersey.
SEC. 2. MEMBERS.
(a) In General.--The Commission shall consist of nine members, as
follows:
(1) The Secretary of the Interior, the Secretary of Housing
and Urban Development, the Secretary of Transportation, and the
Secretary of Commerce, all ex officio.
(2) Five members appointed by the Secretary of the
Interior, one of whom shall be the Director of the National
Park Service, two of whom shall be appointed from
recommendations submitted by the Mayor of the City of Paterson,
one of whom shall be appointed from recommendations submitted
by the Board of Chosen Freeholders of the County of Passaic,
New Jersey, and one of whom shall be appointed from
recommendations submitted by the Governor of the State of New
Jersey. The members appointed pursuant to this paragraph shall
have knowledge and experience in one or more of the fields of
history, architecture, the arts, recreation planning, city
planning, or government.
(b) Substitute Members; Compensation.--(1) Each member of the
Commission specified in paragraph (1) of subsection (a) and the
Director of the National Park Service may designate an alternate
official to serve in his stead.
(2) Members appointed pursuant to paragraph (2) of subsection (a)
who are officers or employees of the Federal Government, the City of
Paterson, the County of Passaic, or the State of New Jersey, shall
serve without compensation as such. Other members, when engaged in
activities of the Commission, shall be entitled to compensation at the
rate of not to exceed $100 per diem. All members of the Commission
shall receive reimbursement for necessary travel and subsistence
expenses incurred by them in the performance of the duties of the
Commission.
SEC. 3. ORGANIZATION.
(a) Chairman.--(1) The Commission shall elect a Chairman from among
its members.
(2) Financial and administrative services (including those relating
to budgeting, accounting, financial reporting, personnel, and
procurement) shall be provided for the Commission by the General
Services Administration, for which payments shall be made in advance,
or by reimbursement, from funds of the Commission in such amounts as
may be agreed upon by the Chairman of the Commission and the
Administrator, General Services Administration. The regulations of the
Department of the Interior for the collection of indebtedness of
personnel resulting from erroneous payments shall apply to the
collection of erroneous payments made to or on behalf of a Commission
employee, and regulations of said Secretary for the administrative
control of funds shall apply to appropriations of the Commission. The
Commission shall not be required to prescribe such regulations.
(b) Staff.--The Commission shall have power to appoint and fix the
compensation of such additional personnel as may be necessary to carry
out its duties, without regard to the provisions of the civil service
laws and the Classification Act of 1949.
(c) Temporary and Intermittent Services.--The Commission may also
procure, without regard to the civil service laws and the
Classification Act of 1949, temporary and intermittent services to the
same extent as is authorized for the executive departments by section
15 of the Administrative Expenses Act of 1946, but at rates not to
exceed $100 per diem for individuals.
(d) Facilities and Services.--The members of the Commission
specified in paragraph (1) of section 2(a) shall provide the
Commission, on a reimbursable basis, with such facilities and services
under their jurisdiction and control as may be needed by the Commission
to carry out its duties, to the extent that such facilities and
services are requested by the Commission and are otherwise available
for that purpose. To the extent of available appropriations, the
Commission may obtain, by purchase, rental, donation, or otherwise,
such additional property, facilities, and services as may be needed to
carry out its duties. Upon the termination of the Commission all
property, personal and real, and unexpended funds shall be transferred
to the Department of the Interior.
SEC. 4. PLAN.
It shall be the duty of the Commission to prepare the plan referred
to in section 1, and to submit the plan together with any
recommendations for additional legislation, to the Congress not later
than eighteen months from the effective date of this Act. The plan for
the Great Falls of the Passaic/S.U.M. Historic District shall include
considerations and recommendations, without limitation, regarding--
(1) the objectives to be achieved by the establishment,
development, and operation of the area;
(2) the types of use, both public and private, to be
accommodated;
(3) criteria for the design and appearance of buildings,
facilities, open spaces, and other improvements;
(4) a program for the staging of development;
(5) the anticipated interpretive, cultural, and
recreational programs and uses for the area;
(6) the proposed ownership and operation of all structures,
facilities, and lands;
(7) areas where cooperative agreements may be anticipated;
and
(8) estimates of costs, both public and private, of
implementing and insuring continuing conformance to the plan.
SEC. 5. TERMINATION.
The Commission shall be dissolved (1) upon the termination, as
determined by its members, of need for its continued existence for the
implementation of the plan and the operation or coordination of the
entity established by the plan, or (2) upon expiration of a two-year
period commencing on the effective date of this Act, whereupon the
completed plan has not been submitted to the Congress, whichever occurs
later.
SEC. 6. PROPOSED AUTHORIZATIONS TO BE INCLUDED IN PLAN.
(a) In General.--It is contemplated that the plan to be developed
may propose that the Commission may be authorized to--
(1) acquire lands and interests therein within the Great
Falls of the Passaic/S.U.M. Historic District by purchase,
lease, donation, or exchange;
(2) hold, maintain, use, develop, or operate buildings,
facilities, and any other properties;
(3) sell, lease, or otherwise dispose of real or personal
property as necessary to carry out the plan;
(4) enter into and perform such contracts, leases,
cooperative agreements, or other transactions with any agency
or instrumentality of the United States, the State of New
Jersey, and any governmental unit within its boundaries, or any
person, firm, association, or corporation as may be necessary;
(5) establish (through covenants, regulations, agreements,
or otherwise) such restrictions, standards, and requirements as
are necessary to assure development, maintenance, use, and
protection of the Great Falls of the Passaic/S.U.M. Historic
District in accordance with the plan; and
(6) borrow money from the Treasury of the United States in
such amounts as may be authorized in appropriations Acts on the
basis of obligations issued by the Commission in accordance
with terms and conditions approved by the Secretary of the
Treasury.
(b) Purchase of Obligations.-- The Secretary of the Treasury is
authorized and directed to purchase any such obligations of the
Commission.
SEC. 7. TITLE TO PROPERTY.
Title to property of the Commission shall be in the name of the
Commission, but it shall not be subject to any Federal, State, or
municipal taxes.
SEC. 8. AUTHORIZATION OF APPROPRIATIONS.
There are authorized to be appropriated not to exceed $200,000 for
the preparation of the plan authorized by this Act. | Establishes the Great Falls Historic District Commission to prepare a plan for the preservation, interpretation, development, and use of the historic, cultural, and architectural resources of the Great Falls of Passaic/S.U.M. National Historic District in Paterson, New Jersey.
Authorizes appropriations for the preparation of the plan. |
Ukrainian President Petro Poroshenko is calling for the deployment of U.N. peacekeepers to monitor a cease-fire in eastern Ukraine, amid reports that at least 13 soldiers were killed while withdrawing from the town of Debaltseve. (Reuters)
Ukrainian President Petro Poroshenko is calling for the deployment of U.N. peacekeepers to monitor a cease-fire in eastern Ukraine, amid reports that at least 13 soldiers were killed while withdrawing from the town of Debaltseve. (Reuters)
Hopes for a cease-fire in Ukraine were fading on Thursday as fighting spread again across the war-torn east a day after a stinging defeat for government forces.
The renewal in combat from the Sea of Azov northward nearly 100 miles to the rebels’ new trophy of Debaltseve, a key railway hub, dimmed hopes for a peace deal reached last week. Rebels said Thursday they would continue to “purge” their new territory of Ukrainian soldiers, threatening further violence in the coming days.
The continued battles came as Ukraine’s government reported steeper losses than it had initially stated in a chaotic pullout from Debaltseve a day earlier. The conflict is increasingly threatening the stability of Ukraine’s government, which must explain to citizens why it allowed an entrapment that led to the bloody denouement on Wednesday. European leaders and the White House also face credibility questions, having threatened tough consequences if the peace plan failed to take hold.
Ukraine’s military said Thursday that at least 13 soldiers were killed and 92 captured on Wednesday alone. An additional 82 soldiers were missing after the pullback from Debaltseve. Prospects for their recovery were grim; many of the troops who escaped said they had left corpses behind in the retreat over the frozen Ukrainian steppe.
[Read: Ukrainian soldiers recall desperate run to safety]
View Graphic Map: Cease-fire pull back lines
After the defeat, Ukrainian President Petro Poroshenko pleaded for U.N. peacekeepers to fan out across Ukraine’s border with Russia, as well as the front line between rebel and government territory. The request amounted to a stark admission that he no longer believes Ukraine can defend itself alone.
But Russian diplomats said Thursday that any such mission would derail the cease-fire agreement reached last week in the Belarusan capital, Minsk, by the leaders of Russia, Ukraine, France and Germany. Russia holds veto power on the U.N. Security Council and could scuttle any proposal for U.N. peacekeepers.
Even many Poroshenko allies questioned the handling of the operation during which thousands of Ukrainian soldiers were encircled and trapped under heavy bombardment by rebel forces. Combined with Ukraine’s grinding economic difficulties, the military debacle means Poroshenko may face an erosion of support in Kiev only eight months after taking power.
Later, Poroshenko told reporters that after the peace deal was signed, rebels and Russian forces “destroyed Debaltseve, wiping it off the face of the Earth. Today Debaltseve resembles a lunar landscape.”
Russia has denied sending its troops to eastern Ukraine in the conflict, which has cost more than 5,600 lives.
The group charged with monitoring the two sides’ compliance with the agreement said Thursday that a key part of the plan — the pullback of heavy weaponry from the front lines — did not appear to be happening, despite claims from both sides that they were doing so.
“The Minsk documents are not a shopping list; it’s one integrated whole,” said Michael Bociurkiw, a spokesman for the Organization for Security and Cooperation in Europe.
1 of 63 Full Screen Autoplay Close March 3, 2015 Tuesday March 2, 2015 Monday Feb. 21, 2015 Saturday Feb. 19, 2015 Feb. 18, 2015 Wednesday Feb. 14, 2015 Saturday Feb. 9 to Feb. 10, 2015 Skip Ad × Violence persists in eastern Ukraine View Photos Fighting between government forces and pro-Russian separatists intensified a day before a cease-fire took effect. Caption As part of the cease-fire, government forces and rebels swapped prisoners. March 5, 2015 An elderly woman walks to a bus stop in Donetsk, Ukraine, a stronghold for pro-Russian rebels. The neighborhood, close to the city's airport, has seen heavy shelling over the past months. John MacDougall/AFP/Getty Images Buy Photo Wait 1 second to continue.
The organization said later that both sides had been using heavy weaponry on Thursday across the region.
Observers have not been allowed into Debaltseve, the scene of the hardest fighting in recent days, Bociurkiw said. Rebel leaders said Thursday that OSCE teams could soon enter — but only after the pro-Russian forces had emptied the town of pro-Ukraine holdouts.
“Tomorrow, or maximum the day after tomorrow, the purge of Debaltseve will be over. The OSCE mission will be able to visit,” said rebel military spokesman Eduard Basurin, according to Russian news agencies. If Ukrainian forces continued shelling rebel positions, the rebels would pull out of the peace deal, he warned.
Fighting flared Thursday near the key Ukrainian-held port city of Mariupol, where an eastern suburb came under heavy artillery attack by rebel forces. Witnesses in Donetsk also reported artillery fire lasting for hours.
In spite of the violence, German Chancellor Angela Merkel and French President François Hollande appeared Thursday to be clinging to hopes that the peace plan would take hold. Merkel’s office said the leaders had agreed to “hold firm to the Minsk agreements despite the grave breach of the cease-fire in Debaltseve.”
But rising discontent could be seen clearly in Ukraine after the military defeat. Borys Filatov, deputy governor of the eastern region of Dnipropetrovsk, urged Poroshenko, nominally an ally, to “live not by lies” after the president said Wednesday that only six soldiers had died in the pullout.
And Semen Semenchenko, a militia commander-turned-lawmaker who is also theoretically a Poroshenko ally, said Thursday that he and other volunteer commanders were forming an alternative “coordinating headquarters” to exchange intelligence and battle planning. The group would exist outside the formal structures of the Ukrainian military, an unusual decision that suggested splits in the military command.
Poroshenko’s request for international peacekeepers would depend on finding a peacekeeping force acceptable to both sides, probably ruling out any involvement for European Union, U.S. or Russian soldiers.
A Ukrainian military spokesman said Thursday that more than 90 percent of its forces had been withdrawn from Debaltseve. Reporters who visited the devastated town Thursday said they heard continued shooting at its outskirts, suggesting that some final holdouts may remain there. Rebels were fully in control of the territory.
The trauma hospital in government-held Artemivsk — about 30 miles northwest of Debaltseve — was largely cleared Thursday of the wounded soldiers who were there a day earlier, although the smell of dirt, sweat and blood lingered in the halls.
Doctors and nurses would not say how many soldiers they had treated.
But Yura Sadyha, 29, a soldier who had returned from the front a few days earlier and volunteered to help carry the wounded into the hospital, said that more than 200 soldiers came through it Wednesday for treatment.
“It’s an awful situation, because so many more people were left on the battlefield,” Sadyha said, rubbing his eyes after working at the hospital for 24 hours straight.
Demirjian reported from Artemivsk. ||||| Image copyright AP Image caption President Poroshenko said about 2,500 troops withdrew from Debaltseve on Wednesday
Russia's UN ambassador Vitaly Churkin has denounced Ukraine's call for the deployment of UN peacekeepers in eastern Ukraine as a destructive move.
The Ukrainian president's call "raises suspicions that he wants to destroy the Minsk accords", Mr Churkin said.
The Minsk ceasefire deal was reached a week ago but fighting round the strategic town of Debaltseve saw the withdrawal of Ukrainian troops there.
Shelling significantly increased in the rebel-held city of Donetsk on Thursday.
And Ukrainian officials reported mortar attacks by separatists on the coastal town of Shirokyne, near Mariupol.
'Violation'
Mr Churkin accused Ukrainian President Petro Poroshenko of seeking a new scheme instead of doing what he had signed up to.
"If one proposes new schemes right away, the question arises whether [the accords] will be respected", he said.
The leadership of the self-proclaimed Donetsk People's Republic described the call for peacekeepers as a violation of the Minsk accords.
The leaders of Russia, Ukraine, Germany and France, the four parties to the Minsk accords, held further talks over the phone on Thursday.
The French presidency said the ceasefire breaches were denounced and the leaders called for "the implementation of the full package of measures agreed in Minsk" including a full ceasefire, withdrawal of heavy weapons and the release of prisoners.
Media playback is unsupported on your device Media caption President Poroshenko met troops who withdrew from Debaltseve
Mr Poroshenko called for UN-mandated peacekeepers to enforce the ceasefire after fighting continued following the rebel advance on Debaltseve.
A police mission by the European Union would be the best format for a peacekeeping operation, Mr Poroshenko said on his website.
It would help guarantee security "in a situation where the promise of peace is not being kept", he told an emergency meeting of Ukraine's national security and defence council.
Analysis: Jonathan Marcus, BBC defence and diplomatic correspondent
Could a peacekeeping force help to secure the ceasefire in eastern Ukraine?
Well for a start there would need to be a functioning ceasefire; nobody is going to send troops into an active war zone. Just getting agreement at the UN for such a force might be an insurmountable diplomatic hurdle.
Russia - with a key veto power on the Security Council - is not just an interested bystander. Despite its denials, it is seen by Ukraine and the West as an active participant in the conflict.
An effective peacekeeping force paradoxically might be in nobody's interests. Peacekeepers tend to fix battle lines in place. In Ukraine both sides probably have further ambitions on the ground. The Russian-backed separatists may well want to advance further and the Ukrainian government's forces certainly aspire to take back territory that they have lost.
Many experts fear there is a lot more fighting to be done whether this ceasefire is implemented or not.
Nearly 2,500 Ukrainian soldiers withdrew from Debaltseve on Wednesday.
Ukraine's army said 82 soldiers were still missing on Thursday. Rebels claim to have captured hundreds.
Earlier a senior Ukrainian military official said 22 Ukrainian soldiers had died in Debaltseve over the past three days. Rebel claims of a much higher figure have been dismissed by the government.
Under threat
The ceasefire, which officially came into effect on Sunday, has reportedly seen some heavy weaponry withdrawn by both sides.
However, the BBC's Ian Pannell in Donetsk reported a significant increase in shelling on Thursday, with artillery fire shaking buildings in the city centre.
Meanwhile Ukrainian military spokesman Anatoliy Stelmakh said rebels had attacked the town of Shirokyne with tanks and weaponry.
After the fall of Debaltseve the peace agreement appears to be under serious threat, our correspondent says.
Earlier rebel spokesman Eduard Basurin said Debaltseve was now "completely under the control" of the separatists, with just "scattered" pockets of resistance that were being "neutralised".
Nato chief Jens Stoltenberg said the rebels' offensive had put the wider peace agreement at risk.
The White House said both the rebels and Russia had failed to live up to the terms of the Minsk agreement.
But Russian Foreign Minister Sergei Lavrov insisted the rebels' actions in Debaltseve had not violated the ceasefire because it was a rebel-held city at the time of the agreement.
Media playback is unsupported on your device Media caption Footage of Debaltseve captured by a drone showed evidence of shelling
Most of the city's 25,000 population has been evacuated but about 5,000 civilians are still believed to be in the town.
Fighting began in eastern Ukraine in April, a month after Russia annexed the Crimea peninsula.
The UN says more than 5,600 people have been killed, but there are fears the actual death toll could be much higher.
Ukraine's pro-Western government says Russia is supporting the separatists with troops and weapons, but the Kremlin has consistently denied this.
Minsk agreement: Key points
Ceasefire from 00:01 on 15 February (22:01 GMT 14 February)
Heavy weapons to be withdrawn, beginning on 16 February and completed in two weeks - beyond a buffer zone behind the current front line for Ukrainian forces and behind the September front line for separatist forces
All prisoners to be released; amnesty for those involved in fighting
Withdrawal of all foreign troops and weapons from Ukrainian territory. Disarmament of all illegal groups
Ukraine to allow resumption of normal life in rebel areas, by lifting restrictions
Constitutional reform to enable decentralisation for rebel regions by the end of 2015
Ukraine to control border with Russia if conditions met by the end of 2015
Do you live in eastern Ukraine or have friends and family in the region? What do you think about the recent developments? You can email your experiences to [email protected]
Please include a contact number if you wish to be contacted by a BBC journalist. ||||| Ukrainian President Petro Poroshenko has called for an international peacekeeping mission for his country after ordering several thousand of his troops out of the strategic eastern Ukrainian town of Debaltseve, which has been taken over by Russia-backed separatists.
Poroshenko's office reported late Wednesday that a meeting of the country's National Defense and Security Council chaired by the Ukrainian president had come to a decision that the United Nations should be asked to send "a peacekeeping mission, which will act in accordance with the mandate of the U.N. Security Council."
The move came just hours after thousands of Ukrainian troops fled Debaltseve, a strategic rail hub that links the separatist strongholds of Luhansk and Donetsk.
The rebels reportedly captured hundreds of government troops and surrounded those it did not take prisoner, cutting off their food and water supplies.
White House comments
The White House said Wednesday that it is "crystal clear" that the separatists in eastern Ukraine and Russia are not living up to the cease-fire agreement negotiated last week in Minsk, Belarus, and warned of possible costs.
“We believe that it is important for all sides to live up to [the Minsk] agreement. It is also crystal clear that Russia-backed separatists and Russia themselves have not lived up to their commitments that they made in the context of [the Minsk] negotiations,” spokesman Josh Earnest told reporters.
Earnest added that the separatists and Moscow may incur “greater costs” and “should be mindful of that as they consider their next steps.”
He said that Washington continues to believe that “the way the situation can be revolved is around the negotiating table."
Map of Debaltseve, Ukraine x Map of Debaltseve, Ukraine
Putin gloats
Tuesday in Hungary, Russian President Vladimir Putin took a more philosophical view of Kyiv's losing control over Debaltseve and said the cease-fire negotiated last week must be implemented.
"Of course, it is always bad to lose. Of course, it is always painful to lose, especially if you lose to yesterday's miners and tractor mechanics," Putin said, referring to rebel fighters Kyiv and many Western goverments claim are supported by Moscow with manpower and weapons. "But life is life, and it will definitely go on.... We should resolve the main task -- save lives of lives of the people who are there now, to insure that they would return to their families, and fulfill the whole plan agreed on in Minsk,'' said Putin.
Germany condemned on Wednesday the pro-Russian separatists' offensive at Debaltseve, calling it a clear violation of a cease-fire agreed to last week, but said it was too early to call the broader Minsk peace deal dead.
Chancellor Angela Merkel's spokesman Steffen Seibert said Europe stood ready to introduce new sanctions against Russia.
Ukrainian President Petro Poroshenko, right, shakes hands with Ukrainian servicemen in the town of Artemivsk, Ukraine, Feb. 18, 2015. x Ukrainian President Petro Poroshenko, right, shakes hands with Ukrainian servicemen in the town of Artemivsk, Ukraine, Feb. 18, 2015.
EU, NATO reaction
Also stepping up Western criticism of the rebel offensive on Debaltseve, European Union foreign policy chief Federica Mogherini said in Brussels, "The actions by the Russia-backed separatists in Debaltseve are a clear violation of the cease-fire.
“The EU stands ready to take appropriate action in case the fighting and other negative developments in violation of the Minsk agreements continue,” she said, making an apparent threat of further economic sanctions on Moscow.
Voicing his concerns about fighting at Debaltseve, NATO Secretary-General Jens Stoltenberg said the refusal of pro-Russian separatists to respect the cease-fire threatened the Minsk accord.
“The refusal of the separatists to respect the cease-fire threatens the agreement, as does their denial of access to the area for the OSCE monitors,” Stoltenberg told reporters in the Latvian capital where he was attending a meeting of European Union defense ministers.
He also said Russian forces, artillery and air defense units were still active in Ukraine.
Watch video report from VOA's Zlatica Hoke:
Tuesday, the U.N. Security Council unanimously adopted a resolution drafted by Russia that supports the Minsk cease-fire deal, while calling for rebels to respect the territorial integrity of Ukraine.
Meanwhile, Ukraine is approaching the first anniversary on February 20 of the Maidan uprising, when months of anti-government protests in Kyiv turned violent, with security forces opening fire on protesters, killing over a hundred of them. The escalation led Ukraine's Moscow-backed president Viktor Yanukovych to flee Kyiv for Russia.
Some material for this report came from Reuters, AP and AFP. | – In an unraveling ceasefire with Russia-backed separatists, Ukraine lost the city of Debaltseve yesterday; the BBC also reports that shelling picked up in the rebel-held city of Donetsk, and that separatists have been conducting mortar attacks in the town of Shirokyne. So it's perhaps not surprising that Ukrainian President Petro Poroshenko asked yesterday for the UN to step in and send peacekeepers to the eastern part of the country, as per the Washington Post. But Russia isn't having any of that, telling its adversary to keep UN peacekeepers out or risk violating the Minsk deal reached last week, the BBC reports. Poroshenko's call for help "raises suspicions that he wants to destroy the Minsk accords," says Vitaly Churkin, the Russian ambassador, per the BBC. "If one proposes new schemes right away, the question arises whether [the accords] will be respected." Poroshenko today called Vladimir Putin, German Chancellor Angela Merken, and French President Francois Hollande—the parties who drafted the ceasefire—and implored them not to act like "what happened in Debaltseve" met ceasefire mandates, the Post reports. The Russian foreign minister says the taking of the city does adhere to the rules, because Debaltseve was held by rebels before the deal, the BBC notes. One analyst for the BBC isn't even sure a peacekeeping mission would work, saying that "nobody is going to send troops into an active war zone," and that Russia and Ukraine will both dig their heels in to take (or take back) what they think is theirs. Still, the White House seems to know where it stands: "It is … crystal clear that Russia-backed separatists and Russia themselves have not lived up to their commitments that they made," press secretary Josh Earnest said yesterday, per Voice of America. Hollande's office issued a statement saying a "new push" was under way to enforce the ceasefire, the Post notes. |
A Kansas University professor who used the n-word during a class discussion about race is on leave while the university investigates a discrimination complaint against her.
Andrea Quenette, assistant professor of communication studies, said she was notified Friday morning that five individuals, whose names she does not know, filed a discrimination complaint against her with KU’s Office of Institutional Opportunity and Access. She said her supervisors agreed to her request for a leave of absence with pay until the investigation concludes.
The formal complaint follows more than a week of public criticism perpetuated by graduate students in the communications department. Students have posted messages to Twitter with the hashtag #FireAndreaQuenette, shared a lengthy letter online and complained about her in a Student Senate meeting Wednesday night.
Sparking their outrage was Quenette’s use of the n-word and statements about retention rates at KU and the concept of systematic racism during her Communications Studies 930 class — focused on best practices for graduate students who teach undergraduate classes — on Nov. 12, the morning after KU’s heated university-wide town hall forum on race.
Quenette, who is 33 and has been teaching at KU for two years, said she believes academic freedom protects her comments and that they were not discriminatory.
“I didn’t intend to offend anyone, I didn’t intend to hurt anyone. I didn’t direct my words at any individual or group of people,” she told the Journal-World tearfully in a phone interview Friday.
“It was an open conversation about a serious issue that is affecting our campus, and it will affect our teachers. In that regard, I consider it within my purview … to talk about those issues.”
The graduate students saw it differently.
“It was outright racism,” said Amy Schumacher, a first-year Ph.D. student who was in the class, which she said is composed of nine white students and one black student. “I don’t think that it was an open dialogue — she wasn’t receptive to hearing any other ideas.”
Schumacher said she believes Quenette “actively violated policies” during the discussion, hurt students’ feelings — including the one black student, who left “devastated” — and has a previous history of being unsympathetic to students.
Class discussion in dispute
Diversity in the classroom was, coincidentally, on the syllabus for Quenette’s Nov. 12 class.
Inspired by the previous night’s forum, Quenette said, a student asked how they could talk about race issues in their own classes, and the conversation naturally shifted to how the university should address problems.
“I tried to preface everything I said with, ‘I don’t experience racial discrimination so it’s hard for me to understand the challenges that other people face, because I don’t often see those,'” said Quenette, who is white.
She said she pointed out that racist incidents on other campuses, including the University of Missouri in Columbia, have been very visible, and she used the n-word when comparing KU to them.
“I haven’t seen those things happen, I haven’t seen that word spray-painted on our campus, I haven’t seen students physically assaulted,” Quenette said.
Quenette said she could have apologized “in the moment” if anyone had responded but that no one did, and the discussion continued.
On the subject of low graduation rates for black students and whether institutionalized racism is to blame — students in class said it was — Quenette said students who don’t graduate do so for a number of reasons, and from what she’s seen at KU it’s often academic performance. Quenette said she’s on a College of Liberal Arts and Sciences committee studying retaining and supporting students, and that “all students” who come to KU with low academic preparedness are at risk.
She acknowledged there was “confusion” during that conversation and that it ended “abruptly” when class was over.
Schumacher, who is also white, described Quenette’s interactions during the conversation as “disparaging” and “deeply disturbing.”
“They articulated not only her lack of awareness of racial discrimination and violence on this campus and elsewhere but an active denial of institutional, structural and individual racism,” Schumacher wrote in the letter signed by the students in the class, plus one other graduate student. “This denial perpetuates racism in and of itself.”
Schumacher said students “had no words” and most “just shut down” after Quenette’s use of the n-word in class.
The next class
Graduate students gathered with other communications faculty and administrators for a town hall of their own on Monday, to which Quenette was asked not to come.
At the next class meeting, on Tuesday, the graduate students demanded that Quenette read aloud their letter, “An Open Letter Calling for the Termination of Dr. Andrea Quenette for Racial Discrimination.”
Quenette said she began reading the letter but stopped partway through, stating that there were legal implications and that she would not read any more.
She then listened as some students read personal statements aloud.
“I feel terrible, upset and sad that I had hurt their feelings and made them feel uncomfortable, because I do care about them as people,” Quenette said. “I felt frustrated by some of the things written in the letter that I don’t remember happening like they described.”
Quenette had prepared a statement of her own to clarify her comments and apologize.
But she said several students said they didn’t want to hear her apology.
“Someone said, ‘No, this is over,’ and they all got up and left,” Quenette said.
Schumacher said students insisted Quenette read their letter aloud “to make sure that she got it.”
She described Quenette as calloused, dismissive and scoffing despite “pain” visible on students’ faces. Schumacher said it became clear that Quenette still was not respecting the students, so they told her they did not want to hear her statement and left.
Social media campaign
Jyleesa Hampton has been one of the main tweeters for #FireAndreaQuenette.
Hampton, a first-year communications graduate student, is not in Quenette’s class but did sign the letter demanding her termination. Hampton said she is one of two black students in the 13-student cohort, and after the Nov. 12 class several students immediately rushed to her office to tell her what had happened.
“People talked about being scared to return to class, scared to have her in charge of their grades,” Hampton said. “I don’t think it will be a safe environment for me” teaching next year, she added.
Hampton said the group took to social media to ensure they were taken seriously.
“My concern was that the university or the department may try and sweep this under the rug or not take this seriously because we are students,” Hampton said. “We wanted to create consciousness about the events in question to provoke a response.
“Social media is a powerful force to bring awareness to instances of racism.”
Investigation open
Quenette said the social media campaign has been “very hurtful.”
Fearing she could lose her job, Quenette said, she hopes to secure an attorney to represent her in KU’s investigation process, and her husband set up a “Go Fund Me” account online to help raise money they need to hire one.
“The current political climate, the nature of the situation, the seriousness of the allegations that have been put forth, I’m in the spotlight and under tremendous pressure,” Quenette said.
Administrative leave means that Quenette is relieved of all teaching and service responsibilities and will remain off campus until the investigation is complete, university spokesman Joe Monaco said. He said such leave is often used “to address substantial disruptions to the learning environment or concerns about individuals’ welfare while IOA conducts its investigation.”
Monaco said IOA’s investigation of Quenette will determine whether the behavior in question — which includes last week’s in-class discussion and other conduct prior to then — violated KU policy and the Faculty Code of Rights, Responsibilities and Conduct.
Where is the line between free speech in the classroom and inappropriate speech?
Chancellor Bernadette Gray-Little, speaking generally Friday in a separate interview with the Journal-World, said that’s difficult to define and can depend on a lot of nuanced factors, down to the goal of the class and a faculty member’s relationships with students.
“I don’t think it’s possible to draw that line in a clear way that everyone will agree that this is on one side and this is on the other,” she said. “I don’t think we’re going to get a bright line.” ||||| Professor on leave after slur
LAWRENCE — A white University of Kansas professor is on paid leave after using a racial slur during a class discussion about race.
The Lawrence Journal-World reports that the university is investigating a discrimination complaint against Andrea Quenette.
The assistant professor of communication studies says she was notified Friday morning that five people filed a discrimination complaint against her.
She requested the leave of absence and the school said she will remain off-campus until the investigation is complete.
Quenette used the slur in her Nov. 12 class after a heated university-wide town hall forum on race following the events at the University of Missouri. She also discussed retention rates at KU and the concept of systematic racism.
She says she “didn’t intend to offend anyone.” ||||| An Open Letter Calling for the Termination of Dr. Andrea Quenette for Racial Discrimination
What follows is a letter collectively written by the students currently enrolled in COMS 930 at the University of Kansas.
To Whom It May Concern:
On the morning of November 12, 2015, a question was posed by Communication Studies Masters student Abigail Kingsford in her COMS 930 class, a required seminar with the primary purpose of instilling best practices in graduate students teaching COMS 130 (public speaking) for the first time. She inquired, “In light of last night’s university-wide town hall meeting about race and discrimination on campus, what is the best approach to talk about that event and these issues with our students?”
We students in the class began discussing possible ways to bring these issues up in our classes when COMS 930 instructor Dr. Andrea Quenette abruptly interjected with deeply disturbing remarks. Those remarks began with her admitted lack of knowledge of how to talk about racism with her students because she is white. “As a white woman I just never have seen the racism…It’s not like I see �?Nigger’ spray painted on walls…” she said.
As you can imagine, this utterance caused shock and disbelief. Her comments that followed were even more disparaging as they articulated not only her lack of awareness of racial discrimination and violence on this campus and elsewhere but an active denial of institutional, structural, and individual racism. This denial perpetuates racism in and of itself. After Ph.D. student Ian Beier presented strong evidence about low retention and graduation rates among Black students as being related to racism and a lack of institutional support, Dr. Quenette responded with, “Those students are not leaving school because they are physically threatened everyday but because of academic performance.” This statement reinforces several negative ideas: that violence against students of color is only physical, that students of color are less academically inclined and able, and that structural and institutional cultures, policies, and support systems have no role in shaping academic outcomes. Dr. Quenette’s discourse was uncomfortable, unhelpful, and blatantly discriminatory.
The university has an obligation to address such behavior. We have met as a cohort and expressed our shock, anger, and pain that the discussion of race in COMS 930 on Thursday, November 12 caused us all. Below we have outlined the specific incidents/comments we found unacceptably offensive.
Use of the n-word.
This phraseology is inhospitable, anti-Black, and unacceptable. It has several negative implications. First, it has negative ramifications for our teaching pedagogy; it creates a model for teaching that is based on discrimination and outright oppression, which is antithetical and counterproductive to the goal of civic engagement crucial to the Basic Course. Second, it prohibits the creation of an inclusive and tolerant culture within the department that involves faculty, staff, and students. Third, it is unprofessional and based upon racially insensitive notions of how language is used and ignores research being produced by our very own department. Dr. Angela Gist gave a great colloquium on her research on the rhetoric of dignity and its implications for creating a positive, productive organizational environment. Furthermore, the usage of racially charged rhetoric ignores the plethora of phenomenological data we have about the way students of color experience the university. Most immediately concerning are the ways this terminology functions as terroristic and threatening to the cultivation of a safe learning environment.
2. The assertion that an inability to see racism means that it does not exist on this campus.
Dr. Quenette indicated that because she has not experienced or witnessed discrimination, it is not happening at KU. She asked for more evidence, and was dismissive of the multiple examples provided. These comments demonstrate not only an unwillingness to accept evidence contrary to her own ideas and experiences but also exemplify the dismissal and questioning of minority students’ experiences that has reinforced the very structural discrimination they seek to destroy by speaking up.
These comments betray a lack of empathy and care for students of color who are facing academic struggles, which is particularly troubling for our incoming cohort of graduate teaching assistants as we are crafting our own teaching pedagogy. Furthermore, it denies the necessity for social and academic institutional programs in support of disenfranchised students.
3. The assumption that retention rates of African-American students is solely due to their lack of academic ability rather than discrimination, structural racism, or institutional barriers.
This discourse is academically irresponsible, morally abhorrent, and patently untrue. To deny the historical legacies of slavery, racial discrimination, and oppression is to perpetuate a space where students are discouraged to ask for access and support as needed. Our concern is that we are being taught that if a minority student approaches us for additional resources or support, we would have no obligation or compelling reason to do so. Nothing in the world is more dangerous than sincere ignorance.
4. The lack of training or constructive strategies provided to better enable us 1) to teach and be inclusive of diverse students and 2) discuss sensitive issues like racism on campus, and the dismissal of the need to add these trainings to COMS 930 and/or the orientation preceding it.
This issue is particularly troubling given the nature of this class and the unique position we are in to foster dialogue and increase understanding. Dr. Quenette unequivocally failed in her official duties as a public employee of this university, director of the Communication Studies Basic Course, and as the instructor of the COMS 930 course when she failed to constructively engage in necessary conversations and provide us the vital tools for improving the inclusiveness of our classrooms.
Furthermore, we have found the comments made by Dr. Quenette actively violate the following policies by which she is bound by her role at the University of Kansas:
The official University of Kansas Racial and Ethnic Harassment policy and corresponding Board of Regents statement, which reads: “The University of Kansas, Lawrence, is committed to programs and activities that are free of racial or ethnic discrimination. To carry out the mission of this institution, the university community must provide and maintain a working and learning environment that fosters respect among all members of the community. The university’s goal is to provide an environment where individuals are free to develop intellectually, personally, professionally, and socially without intimidation or fear. Intimidation and harassment affect not only those who suffer the harassment but also the entire community. Racial and ethnic discrimination is a violation of federal and state law, including Title VII of the Civil Rights Act of 1964 and the Kansas Acts Against Discrimination. The Kansas Board of Regents is particularly concerned about the continuing societal problems of harassment. . . It is the policy of the Board that such conduct cannot and will not be tolerated at the institutions under its governance and control. Each Regents institution shall develop and maintain specific policies which seek to (i) identify prohibited conduct in these areas, (ii) educate campus constituencies with regard to these negative behaviors, (iii) eliminate such behaviors, and (iv) set forth the manner in which such behaviors or conduct are to be addressed” [emphasis added]. The University of Kansas mission statement, which reads: “The university is committed to excellence. It fosters a multicultural environment in which the dignity and rights of the individual are respected. Intellectual diversity, integrity, and disciplined inquiry in the search for knowledge are of paramount importance” [emphasis added]. The College of Liberal Arts and Sciences Mission Statement, which reads: “In the College of Liberal Arts & Sciences at KU, we learn without boundaries. Through our innovative research and teaching, we emphasize interdisciplinary education, global awareness, and experiential learning. This ensures our graduates are engaged, socially responsible citizens who are empowered to build their futures in Kansas and the world” [emphasis added]. Sentiments echoed in the Chancellor’s Letter issued November 13, 2015 which reinforces, “when it comes to racism and discrimination, change is unlikely to happen from the top down. Change has to happen from within our university, and it must involve all of us — administrators, students, faculty, staff and alumni — working together” [emphasis added]. The Communication Graduate Studies handbook, which reads: “The enrollment in COMS 930: Each Graduate Teaching Assistant during the first semester of teaching is required to enroll in the section of 930 entitled “Seminar in Teaching Oral Communication.” The class meets weekly and carries two hours of credit. “Its purpose is to provide the assistant instructor with additional insight and expertise in the teaching fundamentals of oral communication generally, and, in particular, the program as it is conducted at the University of Kansas” [emphasis added].
Dr. Quenette’s deployment of racially violent rhetoric not only creates a non-inclusive environment in opposition to one of the University of Kansas’ core tenets, but actively destroys the very possibility of realizing those values and goals. We are frustrated and disappointed at Dr. Quenette’s lack of efficacious response to the repeated request to have any workshops on reaching diverse students, creating an inclusive classroom space, or discussing sensitive issues. She actively and continually denied the necessity of these trainings.
5. Aggressive, unprofessional behavior unacceptable of a university faculty member and public employee.
We have consistently been concerned throughout the semester with Dr. Quenette’s frequent and extreme defensiveness, continued belittlement of graduate student feedback, and confrontational demeanor in response to anonymous evaluations of the orientation process. Comments that reflected an increased desire for diversity training, representation, and discussion during orientation were cast as irrelevant and unnecessary at multiple junctions in the COMS 930 course. Furthermore, in the COMS 930 course, Dr. Quenette consistently misrepresented and denied speech calling attention to sexist remarks, racially insensitive comments, inappropriate jokes, constant swearing, hostility to alternative teaching methods, and ridicule of incoming GTAs that were all made apparent in the evaluations of orientation and/or during COMS 930 class sessions. Further cause for concern is Dr. Quenette’s multiple violations of anonymity and targeting individual student comments for direct confrontation in relation to these orientation evaluations and in-class comments.
6. A pattern of behavior that indicates recent issues are far from isolated and warrant Dr. Quenette’s termination.
Aside from these most recent transgressions, there are a number of other concerns we have about Dr. Quenette’s continued appointment and presence in the department. These concerns include, but are not limited to: jokes about suicide when asked how we should discuss a recent on-campus suicide with our students, disclosing personal information about other students that may pose external safety risks, and disdain and mockery for graduates in the COMS 930 course who request additional resources and support.
Dr. Quenette has created a culture of disrespect for all students by calling undergraduates “stupid” and doubting their intellectual abilities. Dr. Quenette has made it a habit to disparage the reputations of veteran GTAs in the Communication Studies department by naming them and mocking their classroom policies and procedures, and disclosing private information regarding research projects involving other GTAs. Dr. Quenette exposed information about the personal location of a former GTA in the midst of a domestic violence situation. Dr. Quenette breached FERPA regulations by showing the midterm grades of previous students during the new GTA orientation, specifically, the grades of Cassandra Bird and Michael Eisenstadt.
Given the above concerns that demonstrate Dr. Quenette’s inability to carry out key tenets and responsibilities as the Basic Course Director and COMS 930 instructor we request Dr. Quenette’s immediate termination. Dr. Quenette’s continued presence as department faculty creates an unsafe learning space and hostile work environment which puts at risk students’ ability to complete their degree programs, teach the Basic Course, and fulfill the guiding principals of the department and university writ large.
A number of complaints have been filed with the Office of Institutional Opportunity and Access about this incident and others. The response that more dialogue is needed to resolve this problem is insufficient to redress our claim that the space of dialogue is coded through terror and hostility. The belief that democratic deliberation is neutral is wrong and dangerous. We appreciate the IOA’s commitment to “students’ ability to file complaints and have their voice heard without fear of retaliation.” What is needed now is action upon those complaints. Do not allow the guise of free speech to be invoked and crowd out our demand — legal precedent indicates that Dr. Quenette’s speech is not protected by the First Amendment.
The U.S. Supreme Court ruled in Garcetti v. Ceballos that: “when public employees make statements pursuant to their official duties, the employees are not speaking as citizens for First Amendment purposes, and the Constitution does not insulate their communications from employer discipline.” Admittedly, the Court has not settled on the question of whether or not this analysis extends to “scholarship or teaching.” The situation in which the analysis most consistency does not apply is when a professor communicates as a “citizen speaking on a matter of public concern.” Dr. Quenette was speaking directly about discussing race in our classes while assuming her role as instructor of COMS 930, a course teaching new instructors how to teach well; she was thus speaking pursuant to her official duties and not as a citizen. In Sheldon v. Dhillon, Garcetti did not apply because it could not be determined that a professor was dismissed for “conduct [that] was reasonably related to a legitimate pedagogical concern.” Dr. Quenette’s comments in this specific class, though, clearly demonstrate a legitimate pedagogical concern. The goal of the course is to produce practitioners, so by imbuing racist language, remarks, and viewpoints into the pedagogy her students were meant to replicate, Dr. Quenette was training us to perpetrate acts and ideas violating the policies of the university. Therefore, her speech is not protected by the First Amendment and employer discipline for her remarks is not only legal, but necessary based on her breach of contract.
We want to be absolutely clear that we will not attend this class, we will not accept being graded by Dr. Quenette, we will not recruit, and we will not feel safe to learn and grow as teachers and scholars while under the supervision of Dr. Quenette. Her relationship with the University of Kansas, the Department of Communication Studies, and the Basic Course should be terminated.
Sincerely,
Gabrielle A. Byrd, Jyleesa R. Hampton, Benton J. Bajorek, Ian Beier, Benjamin L. Compton, Matthew D. Kay, Abigail N. Kingsford, Adam R. Raimond, Amy L. Schumacher, Talya P. Slaw, and Joshua Smith ||||| Andrea Quenette is an assistant professor and Basic Course Director in the Communication Studies department at the University of Kansas. In her duties, she is responsible for supervising the public speaking classes in the department and the graduate students who teach and support this program. She is also a researcher and teacher herself. After the events that occurred at the University of Missouri, KU decided to open a dialogue about racial relations at the university. The forum, conducted by the Chancellor, was politically charged and revealed a lot of resentment among students.
Andrea is teaching a required class for all graduate students about college teaching. She has taught this class several times and received positive course reviews from her students. Furthermore, she has never had any complaints, formal or informal, filed against her and she has received positive student evaluations and reviews by peers both in her department at KU but throughout her career.
On the morning of November 12, the day after the forum, she attempted to lead a class discussion on how to address issues of diversity in the classroom. In alignment with the design of the course and the law, discussions in this class were designed to be open, frank and honest conversations representing academic freedom for both students and Andrea. She tried her best to help the students realize that it will not always be easy to see racism, especially if they haven’t experienced it firsthand. She also tried to propose practical solutions and give perspective as an experienced university professor. In this discussion she used a racial slur as an example of ugly language, not directed at any student or individual and in the interest of adding to the discussion. She also explained that as a white person, she was ill-equipped to fully discuss racism because she hasn’t experienced it first-hand. She was honest and tried to be helpful.
What has transpired in the last week has been nothing short of traumatic. The graduate students, offended by her contributions to this discussion have banded together using pressure both on and off campus to wrongfully terminate Andrea without due process. Andrea was advised to go to the next class meeting and listen to the students concerns and apologize for the way the class went. They didn’t allow her to apologize and one student yelled at her. They have mounted a social media misinformation campaign that has made Andrea afraid to go to campus and even pull out of a professional conference. She has barely eaten or slept in 7 days. We have two young children who wonder why Mama is constantly crying. This harassment has been inescapable. The Twitter hashtag #FireAndreaQuenette is particularly disturbing. An open letter has been published full of misinformation and half-truths along with a drastic misrepresentation of the actual class discussion. This was also circulated among Andrea’s colleagues and peers.
Andrea will now need to fight for her job, both at the university level, and possibly in court. We do not know how what our future holds. We came to Kansas with the goal of raising our children and enjoying a town and a university we were proud to be a part of. All of that is now in doubt because of what has happened. Andrea is the least political person I know but she is now being swept along in a charged firestorm. She is a wonderful person, mother, and wife. She is dedicated to her job and requires many of those things from her students.
Any help you can offer is appreciated, we need to consult an attorney and don’t have the money to hire the specialized representation we need. | – A white professor is on leave and under investigation after using the n-word in class—but she says her actions were part of a legitimate conversation about race, the Topeka Capital-Journal reports. Andrea Quenette, an assistant professor of communication studies at the University of Kansas, says she requested a paid leave of absence after learning that five people made a discrimination complaint against her. "I didn’t intend to offend anyone, I didn’t intend to hurt anyone," she tells the Lawrence Journal-World. "It was an open conversation about a serious issue" and thus fair game in class, she says. But Amy Schumacher, a PhD student in Quenette's mostly white class, called it a case of "outright racism." What happened: During a Nov. 12 class for graduate students, Quenette responded to a question about how they should discuss race when teaching undergraduates. At one point, she said she saw little racism on campus: "As a white woman I just never have seen the racism. … It’s not like I see (n-----) spray painted on walls…," she said, according to a long online letter complaining about her. The letter also accuses her of blaming lower black graduation rates at the school on poor academic performance, not racism. Now Quenette has retained a lawyer and her husband has started a GoFundMe page to pay legal bills. But students aren't bending: Quenette "articulated ... her lack of awareness of racial discrimination and violence on this campus and elsewhere," Schumacher says. "This denial perpetuates racism in and of itself." (President Obama made headlines when he used the n-word during an interview.) |
extra - articular manifestations ( exra ) in patients with rheumatoid arthritis ( ra ) have been observed with at a frequency of 17.8 to 40.9% .
exra are associated with comorbidities , erosions , more aggressive disease , high rate for disability , and premature mortality .
it has been described that patients with exra have a 2.5-fold increase in mortality compared with ra without exra .
characteristics associated with exra include male gender , genetics ( hla - drb1 * 04 subtype ) , positive rheumatoid factor ( rf ) , antinuclear antibodies ( ana ) , and some environmental factors particularly smoking [ 4 , 5 ] .
besides of rf and ana , other autoantibodies have been tested as factors associated with exra .
anti - cyclic citrullinated peptide ( anti - ccp ) antibodies are commonly observed in the serum of ra patients , where the frequency varies between 55% and 69% .
although several studies have evaluated the association of anti - ccp with exra , the results have not been always consistent .
in a case - control study found an association of rheumatoid factor ( rf ) and anti - ccp with the presence of exra , although these authors observed a borderline not significant difference in anti - ccp levels in exra compared with their controls without exra . on the other side , korkmaz et al .
did not observe an association between anti - ccp with exra in patients with long disease duration or with early ra .
antibodies against mutated citrullinated vimentin ( anti - mcv ) have been tested most recently for the diagnosis of ra , showing high sensitivity and specificity for the diagnosis of the disease .
nevertheless , there is a lack of information on studies evaluating the association between anti - mcv with exra . to date , to the best of our knowledge
, only one study has evaluated the possible association between anti - mcv antibodies with exra .
these authors did no observe an association between anti - mcv or anti - ccp with exra ; however , this interesting study did not make explicit the methodology to identify exra making it necessary to reevaluate this information .
therefore , because the information about the possible relationship between anti - mcv and exra is still insufficient , we designed a study to evaluate whether there is an association of anti - mcv or anti - ccp with exra .
we evaluated consecutive patients with ra from an outpatient secondary - care center in guadalajara , mexico ( department of internal medicine - rheumatology , hospital general regional 110 , imss ) .
study participants were included if they were mexicans mestizo ( defined as having at least two generations of ancestors born in western mexico ) and only one person per family was recruited . to be included ,
patients with ra had to meet the acr 1987 criteria for ra to have an established diagnosis and be 18 years old or older .
pregnant or nursing patients , those with other autoimmune disorders such as myasthenia gravis , hashimoto tiroiditis , or any overlapping syndrome were excluded .
patients with diagnosis of chronic infections including b or c hepatitis , human immunodeficiency virus , tuberculosis , or other chronic infections were also excluded ( the assessment for these exclusion criteria was based on the information obtained in a chart review of each patient ) .
patients were invited to participate and after signing an informed consent they were assessed by one researcher through a structured interview about epidemiological characteristics ( such as age at the time of the study ) and disease antecedents ; disease duration was defined as the time from the onset of first symptoms of ra until the inclusion in the present study and was assessed through das-28 for disease activity , haq - di for functioning , and other clinical measures .
all the included patients were systematically assessed during the evolution of the disease and at the time of the study for presence of eexra ( table 1 ) , using a structured protocol based on a modification of the criteria described by turesson et al . to identify patients with exra .
briefly , all the patients were systematically assessed by two researchers ( both rheumatologists ) with a structured interrogatory , physical examination , and chart review ; if an exra was suspected , this patient was sent for confirmation to an specialist of the organ being involved ( for example , ophthalmologist , cardiologist , pulmonologist , dermatologist , and nephrologist ) .
the exra assessed included pericarditis ( assessed by clinical judgment and confirmed by echocardiography ) , pleuritis ( assessed by clinical judgment and thorax radiographs ) , felty 's syndrome ( based on clinical evidence of splenomegaly confirmed by ultrasound and neutropenia < 1.8 10 described in at least 2 occasions ) , major cutaneous vasculitis ( based on clinical judgment confirmed by biopsy ) , and neuropathy ( based on clinical judgment and positive results poly / mononeuropathy at electromyography ) .
ocular involvement that was investigated included scleritis , epiescleritis , uveitis , or retinal vasculitis ( these were diagnosed by ophthalmologists ) , glomerulonephritis ( required being corroborated by nephrologist and renal biopsy if required ) , vasculitis involving other organs ( these were identified by an specialist and if required a biopsy was performed ) , amyloidosis ( based on clinical judgment and positive biopsy if required ) , keratonconjunctivitis sicca ( was assessed in all patients and diagnosed if they had positive rose - bengal staining and positive schirmer 's test < 5 mm/5 minutes ) , xerostomia ( clinical judgment and abnormal sialometry and if required with minor salivary gland biopsy showing lymphocytic infiltrate ) , secondary sjgren 's syndrome ( ss ) ( diagnosed if patients met at least two of the following criteria keratonconjunctivitis sicca , xerostomia , positivity for anti - ro , or anti - la antibodies and lymphocytic infiltrate in minor salivary gland biopsy ) .
pulmonary involvement included bronchiolitis obliterans or organizing pneumonia ( based on clinical judgment by a pulmonologist ) , whereas pulmonary fibrosis or interstitial lung disease were diagnosed based on clinical judgment by pulmonologist plus restrictive pattern in lung function test and confirmed by positive findings in high - resolution computed tomography of the lung .
subcutaneous rheumatoid nodules were assessed in the physical examination and the diagnosis based in clinical judgment and biopsy if required .
chronic anemia was diagnosed if a hemoglobin < 11 g / dl was observed at least in 3 occasions in the last 6 months before the evaluation and other causes of anemia were excluded .
severe manifestations were considered in presence of pulmonary fibrosis ( or other entities involving lung ) , moderate or severe pericarditis / pleuritis , vasculitis involving major organs or cutaneous vasculitis with ulcers or gangrene , mono / polyneuritis multiplex , epiescleritis / scleritis , felty 's syndrome , amyloid deposition , and glomerulonephritis . at the same day of the clinical evaluation ,
a venous blood sample was obtained to quantify the titers of anti - ccp and anti - mcv antibodies .
anti - ccp was detected with elisa ( diastat , axis - shield diagnostics limited , uk ) .
positive anti - ccp was defined as a serum concentration 5 iu / ml .
sera with anti - ccp levels above the calibration curve were rerun after dilution to obtain actual semiquantitative values for all samples .
elisa kits for detection of anti - mcv ( orgentec diagnostika gmbh , mainz , germany ) were used according to manufacturer 's instructions with the recommended cut - off value of 20 iu / ml .
rf and c - reactive protein ( crp ) were quantified in serum by nephelometry using a venous blood sample taken at the same day of the evaluation ; the rf was measured on iu / ml and assessed using standard nephelometric assay according to the manufacturer 's specifications ( dade behring , de ) .
a positive result was defined as a level of > 20 ui / ml .
crp was measured on mg / l and assessed using vitros chemistry systems crp slides , according to the manufacture 's specifications ( ortho clinical diagnostics , inc.100.indigo creek drive ; rochester ny 14626 - 5101 ) . erythrocyte sedimentation rate ( esr ) was determined using wintrobe technique .
quantitative variables were expressed as means and standard deviations and qualitative variables in frequency and percentages .
comparisons in proportions between groups were performed with chi - square ( or fisher exact test when required ) and comparisons in means between groups were performed by student 's t - test for independent samples . a logistic regression analysis of factors associated with exra was performed and odds ratios ( or ) and 95% confidence intervals ( 95% ci ) were computed for each variable associated with exra introduced in the final model .
all analyses were performed two - tailed , and statistical significance was considered when p 0.05 .
the study was approved by the research and ethics committee of the hospital in guadalajara , mexico .
the study was approved by the research and ethics committee of the hospital number of approval r-2010 - 1303 - 29 .
the total number of patients invited to participate was 235 with ra , of them 10 patients ( 4.3% ) were excluded for the following reasons : five had overlapping syndrome , two had hepatitis b infection , and three were under study for tuberculosis
.
table 2 describes the clinical characteristics of 225 patients with ra included in the study .
most of them were women ( 92% ) , the mean age was 52.47 years , and 64 ( 28.4% ) had a history of smoking .
regarding the characteristics of the disease , they had a mean for disease duration for 8.97 years , with a das28 score of 5.04 and haq - di score of 0.84 , whereas 94 ( 41.8% ) had steinbrocker radiological stage iii or iv in their hands .
of these 225 patients , 95 ( 42.2% ) had exra , the most frequently observed was ss in 25.8% , chronic anemia in 14.7% , rheumatoid nodules in 10.2% , and peripheral neuropathy in 5.3% .
all the patients included had serological determination of anti - ccp and anti - mcv although only 204 patients had serum determination for rf .
the frequencies of positivity for the autoantibodies were rf 66.2% , anti - ccp 68.9% , and anti - mcv 69.7% .
the mean levels of rf were 119.11 iu / ml , of anti - ccp were 72.44 iu / ml , and of anti - mcv 156.85 iu / ml .
one - hundred and forty patients ( 62.2% ) had positivity for both anti - ccp and anti - mcv antibodies , while 110 patients ( 53.9% ) displayed positivity for anti - ccp , anti - mcv and rf antibodies .
other characteristics of these 225 patients including laboratory variables and their treatments are also shown in this table .
table 3 compares the clinical characteristics as well as the serological profile of ra patients without exra with those with exra .
patients with exra were older ( p = 0.73 ) and had longer disease duration ( p < 0.001 ) , higher number of tender joints ( p = 0.004 ) , higher frequency of steinbrocker radiological stage iii or iv in their hands ( p = 0.01 ) , and higher levels of crp ( p = 0.01 ) .
no differences in titers of rf , anti - ccp , or anti - mcv were observed between patients with ra versus exra . regarding the treatments , a higher proportion of patients without exra were receiving mtx at the time of the study compared with the group with exra ( p = 0.007 ) although no statistical significant differences were observed between exra and the group without exra in mtx dose or anti - tnf agents . in table 4
, we compare the frequency of specific exra of patients with positivity for these autoantibodies versus patients with negativity for these autoantibodies .
frequency of rheumatoid nodules was higher in patients with positive rf ( 14.1% versus 2.9% , p = 0.01 ) , also positive anti - ccp higher frequency of rheumatoid nodules ( 12.9% versus 4.3% , p = 0.048 ) .
similarly , the frequency of rheumatoid nodules was higher in patients with positive anti - mcv as compared with those without these antibodies ( 13.4% versus 2.9% , p = 0.02 ) .
other specific manifestations including ss , chronic anemia , and peripheral neuropathy were not associated with the presence of positivity for these autoantibodies , whereas the number of patients with other specific manifestations such as pulmonary fibrosis , raynaud syndrome , felty syndrome , thrombosis , scleritis , or interstitial vasculitis were too low to allow statistical comparisons . in data not shown in tables , no differences were observed in anti - ccp levels , in patients with ss versus patients without these manifestations ( 69.92 versus 80.15 iu / ml resp . ,
p = 0.48 ) , chronic anemia ( 72.97 versus 69.51 iu / ml resp .
, p = 0.84 ) , rheumatoid nodules ( 69.80 versus 95.33 iu / ml resp . , p = 0.18 ) , or peripheral neuropathy ( 73.77 versus 45.57 iu / ml resp .
similarly , no differences were observed in serum titers of anti - mcv in ss ( 160.86 versus 144.84 iu / ml resp .
, p = 0.57 ) , chronic anemia ( 152.02 versus 184.71 iu / ml resp . ,
p = 0.42 ) , rheumatoid nodules ( 151.59 versus 201.06 iu / ml resp . , p = 0.27 ) , or peripheral neuropathy ( 158.92 versus 121.89 iu / ml resp .
patients with specific manifestations of exra were compared regarding to the number of positive autoantibodies that they had .
patients who had rheumatoid nodules had higher frequency of two or more types of autoantibodies compared with patients without nodules ( 90.9% versus 66.5% resp . ,
the number of autoantibodies was not associated with ss ( p = 0.8 ) , chronic anemia ( p = 0.5 ) , or peripheral neuropathy ( p = 0.4 ) .
again total group patients with exra were not associated with the number of autoantibodies ( p = 0.6 ) .
levels of anti - ccp correlated with the score of the health assessment questionnaire - disability index ( haq - di ) ( r = 0.154 , p = 0.03 ) , erythrocyte sedimentation rate ( esr ) , ( r = 0.155 , p = 0.03 ) , and rf ( p = 0.254 , p < 0.001 ) , whereas anti - mcv titres only correlated with rf ( r = 0.169 , p = 0.02 ) .
table 5 shows a comparison of clinical characteristics between patients who presented a specific exra versus those who did not .
patients with ss had lower age ( p = 0.001 ) and lower disease duration ( p = 0.005 ) , also had a higher proportion of patients diagnosed before year 2000 ( p = 0.009 ) , higher prevalence of chloroquine treatment ( p = 0.008 ) , and lower prevalence of mtx treatment ( p = 0.04 ) .
instead , patients with anemia had a lower das28 ( p = 0.005 ) and lower crp levels ( p = 0.015 ) . in patients with rheumatoid nodules lower disease duration ( p = 0.001 ) ,
higher proportion of patients diagnosed before year 2000 ( p = 0.010 ) , higher proportion of steinbrocker 's score iii or iv ( p = 0.004 ) , higher proportion of + rf ( p = 0.01 ) , higher frequency of + anti - ccp ( p = 0.048 ) , anti - mcv ( p = 0.02 ) , lower frequency of mtx utilization ( p = 0.001 ) , higher proportion of azathioprine users
table 6 shows the results of the multivariate regression analysis of variables associated with exra presence . using the forward stepwise method ,
variables associated with exra were age ( p = 0.015 ) , disease duration ( p = 0.007 ) , das-28 ( p = 0.002 ) , and haq - di ( p = 0.007 ) .
no significant associations were identified between presence of exra with anti - ccp and anti - mcv levels .
our results showed that 42% of our patients had exra ; the variables associated with this involvement in the adjusted analysis are older age , longer disease duration , das-28 score , and haq - di score , whereas no association was observed between anti - ccp or anti - mcv antibodies and exra as general group . for specific exra , there was a weak association between the presence of rheumatoid nodules and positivity for rf , anti - ccp , or anti - mcv antibodies but no relationship was found between these autoantibodies and ss , chronic anemia , or peripheral neuropathy .
the frequency of exra in ra observed in our study is similar to that described by turesson et al .
a review of 12 studies evaluating exra in ra revealed a variation of 17.8% to 40.9% ; this frequency varies depending on the study designs , methodology , and definitions used for the detection of exra as well as characteristics of the center from where the patients were procured .
the most frequent exra observed in our study were ss , chronic anemia , and rheumatoid nodules . among these different studies ,
the frequency of ss and sicca syndrome vary from 7.3% to 19.6% , whereas the frequency of chronic anemia varies between 30% and 70% and rheumatoid nodules have been reported from 2.1% to 38.2% [ 1 , 13 ] . because the main objective of the study was to identify the possible association of anti - ccp or anti - mcv autoantibodies with exra , we examined primarily all the patients that had one or more exra and subsequently , those patients were with a specific exra .
we did not observe an association between the presence of exra as total group and positivity for anti - ccp .
our data differ from observations made by salinas et al . who described a significant association between anti - ccp and exra .
on the other side , turesson et al . observed an association between anti - ccp and exra but only in those patients with severe exra , whereas this association does not persisted when exra was evaluated in general .
unfortunately , a limitation in our study was that the number of patients with severe exra was too small to allow statistical comparisons . regarding the ss
, we did not observe an association between ss and positivity for anti - ccp or anti - mcv antibodies . while some groups designate the ss associated to ra as a
ss , this syndrome could be considered as an overlap disease more than an exra .
barcelos et al . identified that patients with secondary ss had higher frequency of anti - ccp antibodies although their sample was small and therefore is limited in its appropriateness to generalize their results .
we have recently informed the results of a case - control study performed obtained from a different population where we observed a significant association between positivity for anti - ccp antibodies and the presence of interstitial lung disease associated to ra ( ild - ra ) .
nevertheless , in this present study , we were limited to evaluate this association because the low prevalence observed of ild - ra .
we did not observe an association between anti - mcv and exra as total group .
although , as described above , we have found a weak but significant association between positivity for this autoantibody and rheumatoid nodules , finding that requires to be reproduced by other studies .
an association was observed between the nonutilization of mtx and exra , although this association was not observed with dose or anti - tnf agents .
. identified that during the course of treatment , around a half of their patients experienced a decrease in rf or anti - ccp levels .
these data are in concordance with our findings related to lower frequency of exra in mtx users . on the other side nicaise roland et al .
have described that patients with ra treated with infliximab may have a decrease in anti - ccp and anti - mcv levels with the therapy .
we did not identified statistical differences on the frequency of exra in users of anti - tnf agents , nevertheless , a clear limitation for our analysis is the small proportion of patients that were treated with these agents .
our study has several limitations , first because our study was designed to include consecutive patients with ra tested for presence of exra and although we evaluated 225 patients , we were unable to identify a significant number of severe exra , therefore , we did not test associations in these subgroups .
nevertheless , we identified a significant number of patients with nonsevere exra and found no associations except for rheumatoid nodules .
another limitation inherent to this cross - sectional design is that we only tested for anti - ccp and anti - mcv antibodies in one occasion , being necessary in further studies to test these auto - antibodies several times to identify variations in their titers .
hence , further longitudinal studies are required to test if patients with ra with higher titers for these autoantibodies will develop a higher rate of exra in the long - run .
another limitation of our study is the long disease duration observed in some of our patients , in this case is expected that the age of our patients at the time of the study is closely related with ra duration .
therefore we observed in the multivariate analysis that disease duration is relevant confounder in the final model .
relevantly , in the best of our knowledge this is the first study performed in mexican patients that test the association between anti - ccp or anti - mcv anti - bodies with exra , and also is one of the few studies where patients are obtained from a secondary - care center ; this last characteristic constitutes an advantage compared with studies performed in tertiary - care centers where exra is expected be more severe and are more likely to have referral bias . in conclusion , we identified that 42% of our patients with ra have extra - articular manifestations .
variables associated with exra were age , disease duration , das-28 score , and haq - di score .
this study did not observe an association between exra as total group and the positivity or titers of anti - ccp or anti - mcv antibodies .
further studies with more severe exra should be performed to identify if these autoantibodies are associated with these specific manifestations . | we evaluated the association between anti - cyclic citrullinated peptide antibodies ( anti - ccp ) and anti - mutated citrullinated vimentin antibodies ( anti - mcv ) with the presence of extra - articular ( exra ) manifestations in 225 patients with rheumatoid arthritis ( ra ) .
ninety - five patients had exra and 130 had no exra .
there was no association of anti - ccp and anti - mcv levels with the presence of exra as total group ( p = 0.40 and p = 0.91 , resp . ) . making an analysis of individual manifestations , rheumatoid nodules
were associated with positivity for rheumatoid factor ( rf ) ; ( p = 0.01 ) , anti - ccp ( p = 0.048 ) , and anti - mcv ( p = 0.02 ) . instead ,
rf , anti - ccp , or anti - mcv were not associated with ss , chronic anemia , or peripheral neuropathy .
levels of anti - ccp correlated with the score of the health assessment questionnaire - disability index ( haq - di ) ( r = 0.154 , p = 0.03 ) , erythrocyte sedimentation rate ( esr ) ; ( r = 0.155 , p = 0.03 ) , and rf ( p = 0.254 , p < 0.001 ) , whereas anti - mcv titres only correlated with rf ( r = 0.169 , p = 0.02 ) . on adjusted analysis
, exra was associated with longer age ( p = 0.015 ) , longer disease duration ( p = 0.007 ) , higher das-28 score ( p = 0.002 ) , and higher haq - di score ( p = 0.007 ) , but serum levels of anti - ccp and anti - mcv were not associated .
these findings show the need to strengthen the evaluation of the pathogenic mechanisms implied in each specific exra manifestation . |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Urban Flooding Awareness Act of
2015''.
SEC. 2. URBAN FLOODING DEFINED.
(a) In General.--In this Act, the term ``urban flooding'' means the
inundation of property in a built environment, particularly in more
densely populated areas, caused by rain falling on increased amounts of
impervious surface and overwhelming the capacity of drainage systems,
such as storm sewers.
(b) Inclusions.--In this Act, the term ``urban flooding''
includes--
(1) situations in which stormwater enters buildings through
windows, doors, or other openings;
(2) water backup through sewer pipes, showers, toilets,
sinks, and floor drains;
(3) seepage through walls and floors;
(4) the accumulation of water on property or public rights-
of-way; and
(5) the overflow from water bodies, such as rivers and
lakes.
(c) Exclusion.--In this Act, the term ``urban flooding'' does not
include flooding in undeveloped or agricultural areas.
(d) Primary Focus of Study.--Although the definition of the term
``urban flooding'' in this section acknowledges that flooding may be
caused in part by the overflow of rivers or other bodies of water, the
primary focus of the study under section 3 shall be on urban areas
outside of special flood hazard areas, as that term is defined by the
Federal Emergency Management Agency.
SEC. 3. URBAN FLOODING STUDY.
(a) Agreement With National Academy of Sciences.--The Administrator
of the Federal Emergency Management Agency shall enter into an
agreement with the National Academy of Sciences under which the
National Academy of Sciences will conduct a study on urban flooding in
accordance with the requirements of this section.
(b) Contents.--
(1) General review and evaluation.--In conducting the
study, the National Academy of Sciences shall review and
evaluate the latest available research, laws, regulations,
policies, best practices, procedures, and institutional
knowledge regarding urban flooding.
(2) Specific issue areas.--The study shall include, at a
minimum, an examination of the following:
(A) The prevalence and costs associated with urban
flooding events across the United States, with a focus
on the largest metropolitan areas and any clear trends
in frequency and severity over the past 2 decades.
(B) The adequacy of existing federally provided
flood risk information and the most cost effective
methods and products to identify, map, or otherwise
characterize the risk of property damage from urban
flooding on a property-by-property basis, whether or
not a property is in or adjacent to a 1-percent (100-
year) flood plain, and the potential for training and
certifying local experts in flood risk characterization
as a service to property purchasers and owners and
their communities.
(C) The causes of urban flooding and its apparent
increase over the past 20 years, including the impacts
of--
(i) global climate change;
(ii) increasing urbanization and the
associated increase in impervious surfaces; and
(iii) undersized, deteriorating, and
otherwise ineffective stormwater
infrastructure.
(D) The most cost-effective strategies, practices,
technologies, policies, standards, or rules used to
reduce the impacts of urban flooding, with a focus on
decentralized, easy-to-install, and low-cost
approaches, such as nonstructural and natural
infrastructure on public and private property. The
examination under this subparagraph shall include an
assessment of opportunities for implementing innovative
strategies and practices on government-controlled land,
such as Federal, State, and local roads, parking lots,
alleys, sidewalks, buildings, recreational areas, and
open space.
(E) The role of the Federal Government and State
governments, as conveners, funders, and advocates, in
spurring market innovations based on public-private-
nonprofit partnerships. Such innovations may include
smart home technologies for improved flood warning
systems connected to high-resolution weather forecast
data and Internet- and cellular-based communications
systems.
(F) The most sustainable and effective methods for
funding flood risk and flood damage reduction at all
levels of government, including--
(i) the potential for establishing a State
revolving fund program for flood prevention
projects similar to the revolving fund programs
under the Federal Water Pollution Control Act
and the Safe Drinking Water Act;
(ii) stormwater fee programs using
impervious surface as the basis for fee rates
and providing credits for the installation of
flood prevention or other stormwater management
features;
(iii) grant programs; and
(iv) public-private partnerships.
(G) Information and education strategies and
practices, including nontraditional approaches such as
the use of community colleges and social media, for
community leaders, government staff, and property
owners on--
(i) flood risks;
(ii) flood risk reduction strategies and
practices; and
(iii) the availability and effectiveness of
different types of flood insurance policies.
(H) The relevance of the National Flood Insurance
Program and Community Rating System to urban flooding
areas outside traditional flood plains, and strategies
for improving compliance, broadening coverage, and
increasing participation under the programs.
(I) Strategies for protecting communities in the
lower elevations of a watershed or drainage area from
the flooding impacts of development in upstream
communities, including a review of--
(i) potential standards for watershed-wide
flood protection planning; and
(ii) cost-effective and equitable legal
options for a downstream community when
upstream communities act in a way that
increases flooding downstream.
(J) Cost-effective strategies for reducing
infiltration/inflow into combined and separate sewer
systems.
(K) Opportunities to increase coordination between
stormwater management programming under the Federal
Water Pollution Control Act (33 U.S.C. 1251 et seq.)
and flood risk management and mitigation programming
under various laws, including the Robert T. Stafford
Disaster Relief and Emergency Assistance Act (42 U.S.C.
5121 et seq.) and the National Flood Insurance Act of
1968 (42 U.S.C. 4001 et seq.).
(c) Consultation.--
(1) In general.--The Administrator of the Federal Emergency
Management Agency shall carry out this section in consultation
with the Secretary of the Army (acting through the Chief of
Engineers), the Secretary of Housing and Urban Development, the
Administrator of the Environmental Protection Agency, the
Director of the United States Geological Survey, the Chief of
the Natural Resources Conservation Service, the Administrator
of the Small Business Administration, State, regional, and
local stormwater management agencies, State insurance
commissioners, and such other interested parties as the
Administrator of the Federal Emergency Management Agency
considers appropriate.
(2) Cooperation.--The head of each Federal agency referred
to in paragraph (1) shall cooperate with the Administrator of
the Federal Emergency Management Agency in carrying out this
section as requested by the Administrator.
(d) Report to Congress.--Not later than December 31, 2016, the
Administrator of the Federal Emergency Management Agency shall submit
to the Committee on Financial Services and the Committee on
Appropriations of the House of Representatives and the Committee on
Banking, Housing, and Urban Affairs and the Committee on Appropriations
of the Senate a report containing the findings of the National Academy
of Sciences based on the results of the study, including
recommendations for implementation of strategies, practices, and
technologies relating to urban flooding by Congress and the executive
branch. | Urban Flooding Awareness Act of 2015 Directs the Federal Emergency Management Agency (FEMA) to enter into an agreement with the National Academy of Sciences (NAS) to conduct a study on urban flooding. Defines "urban flooding" as the inundation of property in a built environment, particularly in more densely populated areas, caused by rain falling on increased amounts of impervious surface and overwhelming the capacity of drainage systems. Requires the primary focus of the study to be on urban areas outside of special flood hazard areas. Directs the NAS to evaluate the latest research, laws, regulations, policies, best practices, procedures, and institutional knowledge regarding urban flooding. Requires the study to include an examination of: the prevalence of and costs associated with urban flooding events across the United States, with a focus on the largest metropolitan areas and trends in frequency and severity over the past two decades; the adequacy of federally provided flood risk information and the most cost-effective methods and products to characterize the risk of property damage from urban flooding on a property-by-property basis; the potential for training and certifying local experts in flood risk characterization as a service to property purchasers and owners; the causes of urban flooding and its apparent increase; the most cost-effective strategies, practices, technologies, policies, standards, or rules used to reduce the impacts of urban flooding; the role of the federal and state governments in spurring market innovations based on public-private-nonprofit partnerships; the most sustainable and effective methods for funding flood risk and flood damage reduction at all levels of government; the relevance of the National Flood Insurance Program and Community Rating System to urban flooding areas outside traditional flood plains and strategies for improving compliance, broadening coverage, and increasing participation under the Program; strategies for protecting communities in the lower elevations of a watershed or drainage area from the flooding impacts of development in upstream communities; cost-effective strategies for reducing infiltration/inflow into combined and separate sewer systems; and opportunities to increase coordination between stormwater management programming under the Federal Water Pollution Control Act and flood risk management and mitigation programming under various laws. |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Code Talkers Recognition Act of
2008''.
SEC. 2. PURPOSE.
The purpose of this Act is to require the issuance of medals to
express the sense of Congress that--
(1) the service of Native American code talkers to the
United States deserves immediate recognition for dedication and
valor; and
(2) honoring Native American code talkers is long overdue.
SEC. 3. FINDINGS.
Congress finds that--
(1) when the United States entered World War I, Native
Americans were not accorded the status of citizens of the
United States;
(2) without regard to that lack of citizenship, members of
Indian tribes and nations enlisted in the Armed Forces to fight
on behalf of the United States;
(3) the first reported use of Native American code talkers
was on October 17, 1918;
(4)(A) during World War I, Choctaw code talkers were the
first code talkers who played a role in United States military
operations by transmitting vital communications that helped
defeat German forces in Europe;
(B) because the language used by the Choctaw code talkers
in the transmission of information was not based on a European
language or on a mathematical progression, the Germans were
unable to understand any of the transmissions;
(C) this was the first time in modern warfare that such a
transmission of messages in a native language was used for the
purpose of confusing an enemy;
(5) on December 7, 1941, Japan attacked Pearl Harbor,
Hawaii, and Congress declared war the following day;
(6)(A) the Federal Government called on the Comanche Nation
to support the military effort during World War II by
recruiting and enlisting Comanche men to serve in the Army to
develop a secret code based on the Comanche language;
(B) the Army recruited approximately 50 Native Americans
for special native language communication assignments; and
(C) the Marines recruited several hundred Navajos for duty
in the Pacific region;
(7)(A) during World War II, the United States employed
Native American code talkers who developed secret means of
communication based on native languages and were critical to
winning the war; and
(B) to the frustration of the enemies of the United States,
the code developed by the Native American code talkers proved
to be unbreakable and was used extensively throughout the
European theater;
(8) in 2001, Congress and President Bush honored Navajo
code talkers with congressional gold medals for the
contributions of the code talkers to the United States Armed
Forces as radio operators during World War II;
(9) soldiers from the Assiniboine, Cherokee, Cheyenne,
Chippewa/Oneida, Choctaw, Comanche, Cree, Crow, Hopi, Kiowa,
Menominee, Meskwaki, Mississauga, Muscogee, Osage, Pawnee, Sac
and Fox, Seminole, and Sioux (Lakota and Dakota) Indian tribes
and nations also served as code talkers during World War II;
(10) the heroic and dramatic contributions of Native
American code talkers were instrumental in driving back Axis
forces across the Pacific during World War II; and
(11) Congress should provide to all Native American code
talkers the recognition the code talkers deserve for the
contributions of the code talkers to United States victories in
World War I and World War II.
SEC. 4. DEFINITIONS.
In this Act:
(1) Code talker.--The term ``code talker'' means a Native
American who--
(A) served in the Armed Forces during a foreign
conflict in which the United States was involved; and
(B) during the term of service of the Native
American, participated in communication using a native
language.
(2) Recognized tribe.--The term ``recognized tribe'' means
any of the following Indian tribes (as defined in section 4 of
the Indian Self-Determination and Education Assistance Act (25
U.S.C. 450b)):
(A) Assiniboine.
(B) Chippewa and Oneida.
(C) Choctaw.
(D) Comanche.
(E) Cree.
(F) Crow.
(G) Hopi.
(H) Kiowa.
(I) Menominee.
(J) Mississauga.
(K) Muscogee.
(L) Sac and Fox.
(M) Sioux.
(3) Secretary.--The term ``Secretary'' means the Secretary
of the Treasury.
SEC. 5. CONGRESSIONAL GOLD MEDALS.
(a) Award Authorization.--The Speaker of the House of
Representatives and the President pro tempore of the Senate shall make
appropriate arrangements for the award, on behalf of Congress, of gold
medals of appropriate design in recognition of the service of Native
American code talkers of each recognized tribe.
(b) Design and Striking.--
(1) In general.--The Secretary shall strike the gold medals
awarded under subsection (a) with appropriate emblems, devices,
and inscriptions, as determined by the Secretary.
(2) Designs of medals emblematic of tribal affiliation and
participation.--The design of a gold medal under paragraph (1)
shall be emblematic of the participation of the code talkers of
each recognized tribe.
(3) Treatment.--Each medal struck pursuant to this
subsection shall be considered to be a national medal for
purposes of chapter 51 of title 31, United States Code.
(c) Action by Smithsonian Institution.--The Smithsonian
Institution--
(1) shall accept and maintain such gold medals, and such
silver duplicates of those medals, as recognized tribes elect
to send to the Smithsonian Institution;
(2) shall maintain the list developed under section 6(1) of
the names of Native American code talkers of each recognized
tribe; and
(3) is encouraged to create a standing exhibit for Native
American code talkers or Native American veterans.
SEC. 6. NATIVE AMERICAN CODE TALKERS.
The Secretary, in consultation with the Secretary of Defense and
the recognized tribes, shall--
(1)(A) determine the identity, to the maximum extent
practicable, of each Native American code talker of each
recognized tribe;
(B) include the name of each Native American code talker
identified under subparagraph (A) on a list, to be organized by
recognized tribe; and
(C) provide the list, and any updates to the list, to the
Smithsonian Institution for maintenance under section 5(c)(2);
and
(2) determine whether any Indian tribe that is not a
recognized tribe should be eligible to receive a gold medal
under this Act.
SEC. 7. DUPLICATE MEDALS.
(a) Silver Duplicate Medals.--
(1) In general.--The Secretary shall strike duplicates in
silver of the gold medals struck under section 5(b), to be
awarded in accordance with paragraph (2).
(2) Eligibility for award.--
(A) In general.--A Native American shall be
eligible to be awarded a silver duplicate medal struck
under paragraph (1) in recognition of the service of
Native American code talkers of the recognized tribe of
the Native American, if the Native American served in
the Armed Forces as a code talker in any foreign
conflict in which the United States was involved during
the 20th century.
(B) Death of code talker.--In the event of the
death of a Native American code talker who had not been
awarded a silver duplicate medal under this subsection,
the Secretary may award a silver duplicate medal to the
next of kin or other personal representative of the
Native American code talker.
(C) Determination.--Eligibility for an award under
this subsection shall be determined by the Secretary in
accordance with section 6.
(b) Bronze Duplicate Medals.--The Secretary may strike and sell
duplicates in bronze of the gold medals struck under section 5(b), in
accordance with such regulations as the Secretary may prescribe, at a
price sufficient to cover--
(1) the costs of striking the bronze duplicates, including
labor, materials, dyes, use of machinery, and overhead
expenses; and
(2) the costs of striking the silver duplicate and gold
medals under subsection (a) and section 5(b), respectively.
SEC. 8. AUTHORITY TO USE FUND AMOUNTS; PROCEEDS OF SALE.
(a) Authority To Use Fund Amounts.--There are authorized to be
charged against the United States Mint Public Enterprise Fund such
amounts as are necessary to pay for the cost of the medals struck
pursuant to this Act.
(b) Proceeds of Sale.--Amounts received from the sale of duplicate
bronze medals authorized under section 7(b) shall be deposited into the
United States Mint Public Enterprise Fund. | Code Talkers Recognition Act of 2008 - Directs the Speaker of the House of Representatives and the President pro tempore of the Senate to arrange for the award of gold medals in recognition of the service of Native American code talkers of specified Indian tribes. Defines "code talker" as a Native American who served in the Armed Forces during a foreign conflict and who participated in miliatary communications using a native language.
Requires the Secretary of the Treasury, in consultation with the Secretary of Defense and Indian tribes, to identify Native American code talkers eligible for a gold medal. |
SECTION 1. TAX EXEMPT TREATMENT OF CERTAIN BONDS ISSUED IN CONNECTION
WITH DELINQUENT REAL PROPERTY TAXES.
(a) In General.--Section 148 of the Internal Revenue Code of 1986
is amended by redesignating subsection (i) as subsection (j) and by
inserting after subsection (h) the following new subsection:
``(i) Special Rule for Delinquent Tax Bonds.--
``(1) In general.--For purposes of this section, a bond
which meets the requirements of paragraph (2) shall not be
treated as an arbitrage bond.
``(2) Delinquent tax bond requirements.--A bond meets the
requirements of this paragraph if--
``(A) the bond is issued primarily to facilitate
the collection or receipt of delinquent real property
taxes levied for school districts that provide
education primarily below the post-secondary level,
``(B) all sale proceeds of the issue of which the
bond is a part (other than sale proceeds, if any, to be
used for costs of issuance and the establishment of a
reasonably required reserve or replacement fund) are
transferred, within 30 days after the date of issue of
the bond, to governmental units that levy, collect, or
receive real property taxes,
``(C)(i) the amount of the sale proceeds so
transferred does not exceed the amount of delinquent
real property taxes for the year (or the preceding
year) certified by such units to the issuer of the bond
as uncollected, and
``(ii) such certification is made as of a specific
date which occurs during the 5-month period preceding
the date of the issuance of the bond,
``(D) the maturity date of the bond is not later
than 3 months after the date of the issue, and
``(E) all delinquent real property taxes (and
interest, fees, and penalties attributable to such
taxes) received by such governmental units after the
specific date referred to in subparagraph (C) and
before any maturity date of such issue are used, within
3 months of receipt, for the payment of principal,
interest, or redemption price of the issue of which the
bond is a part (to the extent that such taxes,
interest, fees, and penalties do not exceed such
principal, interest, and redemption price, in the
aggregate).
For purposes of this part, proceeds of the issue which are
transferred in accordance with subparagraph (B) shall be
treated as spent on the date so transferred.
``(3) Refunding bonds.--A bond (or series of bonds) issued
to refund a bond meeting the requirements of paragraph (2)
shall be treated as meeting such requirements only if, in
addition to meeting such requirements--
``(A) the maturity date of the refunding bond is
not later than 26 months after the date of issuance of
the original bond, and
``(B) the requirements of subclauses (II) and (III)
of section 144(a)(12)(A)(ii) are met.''
(b) Coordination With Hedge Bond Rules.--Section 149(g)(3) of such
Code is amended by adding at the end the following new subparagraph:
``(D) Exception for delinquent tax bond.--For
purposes of this subsection, the term `hedge bond'
shall not include any bond that meets the requirements
of section 148(i)(2).''
(c) Coordination With Pooled Financial Bond Rules.--Section
149(f)(4)(B) of such Code is amended--
(1) by striking ``or'' at the end of clause (i),
(2) by striking the period at the end of clause (ii) and
inserting ``, or'', and
(3) by adding at the end the following new clause:
``(iii) section 148(i) applies to such
bond.''
(d) Coordination With Private Activity Bond Rules.--Paragraph (2)
of section 141(c) of such Code (relating to private activity bond;
qualified bond) is amended by striking ``or'' at the end of
subparagraph (A), by striking the period at the end of subparagraph (B)
and inserting ``, or'', and by adding at the end the following new
subparagraph:
``(C) is with respect to a bond which meets the
requirements of section 148(i)(2) (relating to
delinquent tax bonds).''
(e) Effective Date.--The amendments made by this section shall
apply to bonds issued after the date of the enactment of this Act. For
purposes of the preceding sentence, a bond (or series of bonds) issued
to refund a bond shall be treated as being issued on the date of
issuance of the refunded bond, if the refunding bond meets the
requirements of subclauses (I), (II), and (III) of section
144(a)(12)(A)(ii) of the Internal Revenue Code of 1986. | Amends the Internal Revenue Code to provide that certain bonds issued by local governments in connection with delinquent real property taxes (delinquent tax bonds) may be treated as tax exempt.Requires: (1) such a bond to be issued (with a three-month maturity date) primarily to facilitate the collection or receipt of delinquent real property taxes levied for school districts that provide education primarily below the post-secondary level; and (2) that all delinquent real property taxes (and interest, fees, and penalties attributable to them) received by such governmental units after a specified date but before any maturity date are used, within three months of receipt, for the payment of principal, interest, or redemption price of the issue of which the bond is a part (to the extent that such taxes, interest, fees, and penalties do not exceed such principal, interest, and redemption price, in the aggregate). |
galaxy clusters provide one of the most powerful tools to constrain the key cosmological parameters . in the era of precision cosmology
, it is important to determine their mass as accurately as possible before using them as a cosmological probe .
any kind of simplified assumption about the properties of galaxy clusters could cause substantial systematics in the mass estimation .
the triaxial shapes of galaxy clusters are one of such properties .
it has been long known both observationally and numerically that the galaxy clusters are noticeably triaxial ( e.g. , * ? ? ? * ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ) . while plenty of efforts have been already made to take into account the triaxial shapes of galaxy clusters @xcite , previous studies have been largely focused on the statistical treatment of cluster triaxiality
for the measurement of the gas mass fraction of galaxy clusters that can provide powerful constraints on the density parameter and the dark energy equation of state @xcite , however , it is necessary to deal with the individual clusters and their triaxial shapes .
the standard picture based on the cosmic web theory @xcite explains that galaxy clusters are rare events corresponding to the local maxima of the initial density field and form at the dense nodes of the local filaments in the cosmic web through tidal interactions with the surrounding matter . the tidal effect from the surrounding matter results in the deviation of cluster shapes from spherical symmetry as well as the preferential alignments of cluster galaxies ( or halos ) with the major axes of their host clusters @xcite . in the frame of this standard scenario , (
* hereafter , lk06 ) have recently developed an analytic algorithm to reconstruct the triaxial shapes of individual clusters .
the key concept of the lk06 algorithm is that the two axial ratios of a triaxial cluster are related to the eigenvalues of the local tidal shear tensor . by measuring the spatial alignment of the cluster galaxies with the major axis of their host cluster
, one can determine the eigenvalues of the local tidal tensor , which will in turn yields the two axial ratios of a triaxial cluster .
testing their analytic model against high - resolution n - body simulations , lk06 have shown that their algorithm works well within @xmath4 errors .
now that the lk06 algorithm is known to work in principle , it is time to test the algorithm against observations .
our goal here is to apply the lk06 algorithm to real observational data and examine its validity in practice . here
, we use the virgo cluster as a target , whose triaxial shape has been very recently measured observationally @xcite .
the organization of this paper is as follows . in 2 , a brief overview of the lk06 algorithm
is provided and how to incorporate the two dimensional projection effect into the algorithm is explained . in 3 , the virgo cluster data are analyzed and its triaxial shapes are reconstructed using the lk06 algorithm . in 4 ,
the results are summarized , and the advantages and the caveats of our model are discussed .
according to the lk06 algorithm , the cluster triaxial shape originates from its tidal interaction with the surrounding matter distribution .
this assumption has been verified from high - resolution n - body simulation which demonstrated clearly that the tidal field elongates the cluster shapes ( e.g. , * ? ? ? * and references therein ) .
lk06 has shown that the two axial ratios of a triaxial cluster are related to the three eigenvalues of the local tidal tensor defined as the second derivative of the gravitational potential : @xmath5 where @xmath6 ( with @xmath7)are the three principal axis lengths of a cluster and @xmath8 ( with @xmath9 ) are the three eigenvalues of the local tidal tensor , @xmath10 . according to this formula , one can estimate the cluster axial ratios if @xmath11 is fixed by fitting the probability density distribution , @xmath12 analytically to the observational data .
lk06 suggested that the preferential locations of the cluster galaxies near the cluster major axes given the local tidal tensor be described as @xmath13 where @xmath14 is the unit position vector of a cluster galaxy , @xmath15 is the unit tidal shear tensor , and @xmath16 $ ] is the correlation parameter that represents the correlation strength between @xmath17 and @xmath18 . under the assumption that the minor axis of the tidal shear tensor is in the direction of the cluster major axis , equation ( [ eqn : corr ] ) basically describes the alignment between the position of a cluster galaxy and the major axis of its host cluster .
if @xmath19 , there is a maximum alignment .
if @xmath20 , there is a maximum anti - alignment .
the case of @xmath21 corresponds to no alignment .
let @xmath22 be the angle between the host cluster major axis and the galaxy position vector . under the assumption that the cluster major axis is in the direction of the minor principal axis of the tidal shear tensor , the probability density distribution of @xmath23 was derived by lk6 as @xmath24 where @xmath25 is an azimuthal angle of @xmath17 measured in an arbitrary coordinate system . here , covariance matrix @xmath26 is defined as @xmath27 .
note that equation ( [ eqn : gen ] ) holds good for any arbitrary coordinate system in which the tidal shear tensor is not necessarily diagonal . in the principal axis frame of the tidal tensor , equation ( [ eqn : pri ] ) can be expressed only in terms of the three eigenvalues of the tidal shear tensor as @xmath28 where @xmath29 are the eigenvalues of @xmath18 , related to @xmath30 as @xmath31 where @xmath32 is the linear density threshold for a dark halo @xcite satisfying the following constraint of @xmath33 .
the key concept of lk06 algorithm is that by fitting equation ( [ eqn : gen ] ) to the observed probability distribution , one can find the best - fit values of @xmath34 and @xmath35 , and then determine the cluster axial ratios using equation ( [ eqn : axi ] ) .
although lk06 algorithm allows us in principle to reconstruct the three dimensional intrinsic triaxial shapes of individual clusters , it is restricted to the cases where the informations on the three dimensional positions of the cluster galaxies in the cluster principal axis frame are given .
unfortunately , for most clusters , these informations are not available but only two dimensional projected images of clusters . in @xmath36
, we attempt to modify the lk06 algorithm in order to incorporate the two dimensional projection effect .
let us suppose that the position vectors of the cluster galaxies are all projected along the line of sight direction onto the plane of a sky . unless the major axis of the host cluster is perfectly aligned with the line - of - sight direction to the cluster center , one would expect that the projected position vectors of the cluster galaxies should show a tendency to be aligned with the projected major principal axes
. let @xmath37 be the angle between the projected cluster major axis and galaxy position vector in the plane of sky .
the probability distribution can be calculated by integrating equation ( [ eqn : gen ] ) along the line of sight as @xmath38 where @xmath39 is now chosen to be in the direction of the line of sight .
in other words , we consider a certain cartesian coordinate system in which the @xmath40 direction is parallel to the line of the sight to the cluster center of mass .
note that in this coordinate system the tidal tensor is not necessarily diagonal . through the similarity transformation @xmath41 with @xmath42 one
can express the nondiagonal unit tidal tensor @xmath18 in terms of its eigenvalues.here , the rotation matrix @xmath43 has the form of @xcite @xmath44 where @xmath45 is the polar coordinate of the line - of - sight direction in the principal axis frame of the cluster . through equations ( [ eqn:2dp])-([eqn : bin ] )
, we finally final an analytic expression for the probability density distribution of @xmath46 in terms of @xmath47 and the correlation parameter @xmath35 : @xmath48 with the factor @xmath49 defined as @xmath50(a_1\hat{\lambda}_{1}+a_2\hat{\lambda}_{2 } + a_3\hat{\lambda}_{3})(1 - \hat{x}^{2}_{3 } ) , \nonumber \\ & & + [ ( 1 + s)^2 - 3s(1 + s)](c_1\hat{\lambda}_{1 } + c_2\hat{\lambda}_{2 } + c_3\hat{\lambda}_{3})\hat{x}^{2}_{3 } , \nonumber \\ & & + 6s(1 + s)(b_1\hat{\lambda}_{1}+ b_2\hat{\lambda}_{2 } + b_3\hat{\lambda}_{3})\hat{x}_{3}\sqrt{1 - \hat{x}^{2}_{3}},\end{aligned}\ ] ] where the coefficients @xmath51 are given as @xmath52 with this new modified algorithm in the two dimensional space , we can reconstruct the intrinsic shape of a triaxial cluster halo from the observed two dimensional image .
the virgo cluster is the nearest richly populated cluster of galaxies whose properties has been studied fruitfully for long . it is known to have approximately @xmath0 member galaxies @xcite and located at a distance of approximately @xmath53 mpc from us @xcite with the major axis inclined at an angle of approximately @xmath54 with respect to the line of sight @xcite . near the center of the virgo cluster
is located the large ellipticity galaxy @xmath55 ( or virgo a ) .
the major axis of the virgo cluster is found to be inclined approximately @xmath56 with respect to the line of sight direction to @xmath55 @xcite .
we use data from the virgo cluster catalogue @xcite which compiles the equatorial coordinates of total @xmath0 member galaxies .
let @xmath57 and @xmath58 represent the three dimensional distance to a member galaxy and its equatorial coordinates , respectively . under the assumption that the position of @xmath55 is the center of mass of the virgo cluster , the cartesian coordinate of a member galaxy in the center of mass frame can be written as @xmath59 where @xmath60 represents the position of @xmath55 .
the equatorial coordinates of @xmath55 is measured to be @xmath61 and @xmath62 .
the distance to virgo a , @xmath63 , from us is also known to be approximately @xmath53mpc ( @xcite ; sbf survey ) .
thus , we have a full information on @xmath60 .
now let us consider a coordinate system where the third axis is in in the direction of the line of sight to @xmath55 .
let @xmath64 be the spherical polar coordinate of the member galaxy in this coordinate system .
it can be found through coordinate transformation as @xmath65 where @xmath66 is the polar coordinate of m87 , so that @xmath67 . in the plane of sky projected along the line of sight direction , the spherical polar coordinates of the member galaxy can be regarded as the cartesian coordinates as @xmath68 , @xmath69 , and @xmath70 .
basically , it represents a two dimensional projected position of a virgo cluster member galaxy in the plane of sky with the position of @xmath55 as a center . for each member galaxy from the virgo cluster catalogue
, we have determined the two dimensional projected position @xmath71 using the given equatorial coordinates . to measure the alignments between the positions of the virgo cluster galaxies and the projected major axis of the virgo cluster and compare the distribution of the alignment angles with the analytic model ( eq.[[eqn:2dp ] ] ) ,
it is necessary to find the direction of the projected major axis in the coordinate system of @xmath72 .
equivalently , it is necessary to have an information on the polar coordinates of the line of sight , @xmath73 with respect to the three dimensional principal axis of the virgo cluster .
the seminal paper of @xcite provides us with the information on @xmath74 i.e. , the angle between the three dimensional major axis of the virgo cluster and the line of sight direction as approximately @xmath56 .
however , we still need the azimuthal angle @xmath75 of the major axis of the virgo cluster . to find the azimuthal angle @xmath75 , we first let @xmath76 and @xmath77 in the analytic model ( eq.[[eqn:2dp ] ] ) .
it implies that we choose a certain cartesian coordinates @xmath78 where the angle @xmath75 vanishes .
then , we transform the coordinate system of @xmath72 into this new coordinate system as @xmath79 here , note that @xmath80 corresponds to the projected major axis of the virgo cluster in the @xmath72 coordinate system .
it is expected that in this new @xmath78-coordinate system the the observationally measured distribution should fit the analytic model ( eq.[[eqn:2dp ] ] best . for a given @xmath75
, we measure the alignment angle between the projected major axis and position vector of each virgo cluster galaxy as @xmath81 where @xmath82 .
then , by counting the number of galaxies galaxy s number density as a function of @xmath83 , we can derive the probability distribution , @xmath84 .
we fit this observational distribution with the analytic model , adjusting the values of @xmath34 and @xmath35 through @xmath85-minimization .
we repeart the whole process varying the value of @xmath75 , and seek for the value of @xmath75 which yields the smallest @xmath85 value . as a final step ,
we determine the corresponding best - fit values of @xmath86 and @xmath87 .
finally , we find the axial ratios of the virgo cluster to be @xmath88 and @xmath89 by using equation ( [ eqn : axi ] ) with the constraint of @xmath33 .
the best - fit value of @xmath35 is also determined to be @xmath90 , indicating that the positions of the cluster galaxies are indeed aligned with the major axes of the virgo cluster .
figure [ [ fig : plane ] ] plots the two dimensional projected positions of the virgo cluster galaxies in the @xmath78-coordinate system .
the arrow represents the direction of the projected major axis determined from the chosen value of @xmath75 .
figure [ fig : fit ] plots the probability distribution of the alignment angles for four different cases of @xmath75 . in each panel ,
the histogram with poisson errors is the observational distribution while the solid line represents the analytic fitting model .
the dotted line stands for the case of no alignment at all .
the top left panel corresponds to the finally chosen value of @xmath75 for which the analytic fitting model and the observational result agree with each other best .
the other three panels show the three exemplary cases of @xmath75 for which the analytic fitting model and the observational result do not agree with each other well with relatively high @xmath85 value . to investigate whether the reconstructed axial ratios of the virgo cluster changes with the radius from the center , we introduce a cut - off radius , @xmath91 , and remeasure the axial ratios using only those galaxies located within @xmath91 from the center in the @xmath78- corrodinate system .
we repeat the same process but using four different values of @xmath91 .
table [ tab : fit ] lists the values of the resulting best - fit axial ratios @xmath92 and @xmath93 , and the best - fit correlation parameter for the four different cut - off radii of @xmath94 .
as can be seen , at the inner radius smaller than the maximum one , the shape tends to be more prolate - like , consistent with recent numerical report ( e.g. , * ? ? ?
note also that the value of @xmath35 is consistently @xmath90 , which implies the strength of the tidal interaction with surrounding matter is consistent .
figure [ fig : radii ] plots the probability distributions for the four different cases of @xmath91 .
the top left panel shows the case of maximum cut - off radius .
as can be seen , the agreements between the analytic fitting model and the observational result are quite good even at inner radii .
we have modified the cluster reconstruction algorithm which was originally developed by @xcite to apply it to the two dimensional projected images of galaxy clusters in practice . assuming that unless the cluster major axes are in the line - of - sight direction , we have found that the alignments between the galaxy positions and the projected major axes can be used to reconstruct the two axial ratios of the triaxial clusters .
we have applied the modified algorithm to the observational data of the virgo cluster and shown that the reconstructed axial ratios of ( @xmath1 : @xmath2 : @xmath3 ) are in good agreement with the recent report from the virgo cluster survey @xcite , which proves the validity and usefulness of our method in practice .
now that the virgo cluster is found to be triaxial , let us discuss on the triaxiality effect on the mass estimation . for simplification ,
let us assume that the virgo cluster has a uniform density .
then , the mass of the triaxial virgo cluster with the axial ratios given as @xmath95 is estimated to be @xmath96 times larger than the spherical case since the spherical radius is close to the minor axis length of the virgo cluster since the major axis of the virgo cluster is very well aligned with the line of sight direction .
therefore , it can cause maximum @xmath97 errors to neglect the virgo cluster triaxiality .
the most prominent merit of our method over the previous one is that it reconstructs directly the _ intrinsic three dimensional structures _ of the underlying triaxial dark matter halo using the fact that the cluster triaxiality originated from the tidal interaction .
conventionally , the triaxial shape of a cluster is found through calculating its inertia momentum tensor .
this conventional method , however , is unlikely to yield the _ intrinsic _ shape of the underlying dark matter halo unless the target cluster is a well relaxed system .
in addition , our method does not resort to any simplified assumption like the axis - symmetry or the alignment with the line - of - sight and etc .
yet , it is worth mentioning here a couple of limitations of our method .
first , it assumes that the major axes of the clusters are not aligned with the line - of - sight direction so that the alignments between the galaxy positions and the projected major axes can be measured .
second , for the virgo cluster , the crucial information on the angle @xmath74 between the three dimensional major axis and the line of sight has been already given @xcite . which simplifies the whole of our method since it was only @xmath75 that has to be determined .
for most clusters , however , this information is not given , so that both the values of @xmath74 and @xmath75 have to be determined through fitting before finding the axial ratios .
third , its success is subject to the validity of the lk06 algorithm .
according to the numerical test , the lk06 algorithm suffers approximately @xmath4 errors for the case that the number of the member galaxies is not high enough .
it implies that the lk06 algorithm is definitely restricted to the rich clusters with large numbers of galaxies .
therefore , it may be necessary to refine and improve the lk06 algorithm itself for the application to poor cluster samples .
our future work is in this direction .
100 algood , b. et al .
2006 , , 367 , 1781 altay , g. , colberg , j. m. , & croft , r. a. c. 2006 , , 370 , 1422 anninos , p. , & norman , m. l. 1996 , , 459 , 12 bardeen , b. , bond , r. j. , kaiser , n. , & szalay , h. 1986 , , 23 , 567 basilakos , s. , plionis , m. , & maddox , s.j .
2000 , , 316 , 779 binggeli , b. 1982 , , 107 , 338 binggeli , b. , sandage , a. , & tammann , g. , a. 1985 , , 90 , 1681 binney , j. 1985 , , 212 , 767 bohringer , h. et al .
1994 , nature , 368 , 828 bond , j. r. , kofman , l. , & pogosyan , d. 1996 , nature , 380 , 603 cen , r. 1997 , , 485 , 39 cooray , a. r. 1998 , , 339 , 623 eke , v. r. , cole , s. , & frenk , c. s. 1996 , , 282 , 263 evrard , a. e. 1997 , , 292 , 289 fabricant , d. , gorenstein , p. 1983
, , 267 , 535 ferramacho , l. d. , & blanchard , a. 2007 , , 463 , 423 fouque , p. s. , solanes , j. m. , sanchis , t. , & balowski , c. 2001 , , 375 , 770 fox , d. c. , & pen u. l. 2002 , , 574 , 38 frenk , c. s. , white , s. d. m. , davis , m. , efstathiou , g. 1988 , , 327 , 507 hayashi , e. , navarro , j. f. , & springel , v. 2007 , accepted hopkins , p. f. , bahcall , n. , & bode , p. 2005
, , 618 , 1 jing , y.p . , & suto , y. 2002 , , 574 , 538 kasun , s. f. , evrard , a. e. 2005 , , 629 , 781 klypin , a. , cottlober , s. , & kravtsov , a. v. 1999 , , 516 , 530 laroque , s. j. 2006 , , 652 , 917 lee , j. , pen , u. l. 2001 , , 555 , 106 lee , j. , suto , y. 2003 , , 585 , 151 lee , j. , suto , y. 2004 , , 601 , 599 lee , j. , kang , xi , & jing , y. p. 2005
, , 639 , l5 lee , j. , kang , xi 2006 , , 637 , 561 lokas , e. l. , mamon , g. a. 2003 , , 343 , 401 lubin , l. m. , cen , r. , bahcall , n. a. , & ostriker , j. p. 1996
, apj , 460 , 10 mamon , g. a. , sanchis , t. s. , & solanes , j. m. 2004 , , 414 , 445 mclaughlin , d. e. 1999 , , 512 , l9 mei , s. et al .
2007 , , 655 , 144 mohr , j. j. , mathiesen , b. , & evrard , a .
e. 1999 , , 517 , 627 nulsen , p. e. j. , bohringer , h. 1995 , , 274 , 1093 paz , d. j. , lambas , d. g. , padilla , n. , & merchan , m. 2006 , , 366 , 1503 plionis , m. , barrow , j. d. , & frenk , c. s. 1991 , , 249 , 662 sanderson , a. j. r. 2003 , , 340 , 989 schindler , s. , binggeli , b. , & bohringer , h. 1999 , , 343 , 420 smith , r. e. , & watts , p. i. r. 2005 , , 360 , 203 solanes , j. m. 2002 , , 124 , 2440 struble , m. f. , peebles , p. j. e. 1985 , , 90 , 582 suto , y. , sasaki , s. , & makino , n. 1998 , , 509 , 544 suwa , t. , habe , a. , yoshikawa , k. , & okamoto , t. 2003 , , 588 , 7 tonry , j. l. et al .
2001 , , 546 , 681 warren , m. s. , quinn , p. j. , salmon , j. k. , zurek , w. h. , , 399 , 405 west , m. j. 1989 , , 347 , 610 west , m. j. , blakeslee , j. p. 2000 , , 543
, l27 white , s. d. m. , navarro , j. , & evrard , a. e. , & frenk , c. s. 1993 , nature , 366 , 429 zentner , a. r. et al .
2005 , , 629 , 219 ccccc @xmath98 & @xmath0 & @xmath99 & @xmath3 & @xmath90 + @xmath100 & @xmath101 & @xmath102 & @xmath103 & @xmath90 + @xmath104 & @xmath105 & @xmath102 & @xmath103 & @xmath90 + @xmath106 & @xmath107 & @xmath102 & @xmath103 & @xmath90 + [ tab : fit ] | to use galaxy clusters as a cosmological probe , it is important to account for their triaxiality . assuming that the triaxial shapes of galaxy clusters are induced by the tidal interaction with the surrounding matter , lee and kang recently developed a reconstruction algorithm for the measurement of the axial ratio of a triaxial cluster .
we examine the validity of this reconstruction algorithm by performing an observational test of it with the virgo cluster as a target .
we first modify the lk06 algorithm by incorporating the two dimensional projection effect .
then , we analyze the @xmath0 member galaxies from the virgo cluster catalogue and find the projected direction of the virgo cluster major axis by measuring the anisotropy in the spatial distribution of the member galaxies in the two dimensional projected plane . applying the modified reconstruction algorithm to the analyzed data , we find that the axial ratio of the triaxial virgo cluster is ( @xmath1 : @xmath2 : @xmath3 ) .
this result is consistent with the recent observational report from the virgo cluster survey , proving the robustness of the reconstruction algorithm .
it is also found that at the inner radii the shape tends to be more like prolate .
we discuss the possible effect of the virgo cluster triaxiality on the mass estimation . |
a stochastic cellular automata ( ca ) model of pedestrian flow is considered here .
our model takes inspiration from stochastic floor field ( ff ) ca model @xcite that provides pedestrians with a map which `` shows '' the shortest distance from current position to a target . in this paper
we focus on mathematical formalizing and implementation to the model such behavioral aspects of decision making process as : while moving people follow at least two strategies the shortest path and the shortest time
. strategies may vary , cooperate and compete depending on current position .
this is a next attempt to extend basis ff model towards a behavioral aspect making more flexible / realistic decision making process and improve simulation of individual and collective dynamics of people flow .
the space ( plane ) is known and sampled into cells @xmath0 which can either be empty or occupied by one pedestrian ( particle ) only @xcite .
cells may be occupied by walls and other nonmovable obstacles .
so space is presented by 2 matrixes : @xmath1 @xmath2 a _ static floor field _ ( sff ) @xmath3 is used in the model .
field @xmath3 coincides with the sampled space .
a value of each @xmath4 saves the shortest distance from cell @xmath5 to a nearest exit ; i.e. , s increases radially from exit cells where @xmath4 are zero .
it does nt evolve with time and is nt changed by the presence of the particles .
one can consider @xmath3 as a map that pedestrians use to move to the nearest exit .
starting people positions are known . a target point for each pedestrian
is the nearest exit .
each particle can move to one of four its next - neighbor cells or to stay in present cell ( the von neumann neighborhood ) at each discrete time step @xmath6 fig .
[ fig1 ] ; i.e. , @xmath7 .
( 230,90 ) ( 0,0)(1,0)90(0,30)(1,0)90(0,60)(1,0)90(0,90)(1,0)90(0,0)(0,1)90(30,0)(0,1)90(60,0)(0,1)90(90,0)(0,1)90(45,45)(-1,0)30(45,45)(1,0)30(45,45)(0,1)30(45,45)(0,-1)30(45,45)(140,0)(1,0)90(140,30)(1,0)90(140,60)(1,0)90(140,90)(1,0)90(140,0)(0,1)90(170,0)(0,1)90(200,0)(0,1)90(230,0)(0,1)90(152.5,9.5)0(211.5,9.5)0(152.5,69.5)0(211.5,69.5)0(145,43)@xmath8(179,43)@xmath9(175,13)@xmath10(175,73)@xmath11(205,43)@xmath12
+ generally speaking , a direction for each particle at each time step is random and determined in accordance with a transition probabilities distribution ( and transition rules ) . so a main problem is to determine `` right '' transition probabilities ( and transition rules ) .
a typical scheme for stochastic ca models is used here .
there is step of some preliminary calculations . then at each time
step transition probabilities are calculated , and direction is chosen . if there are more then one candidates to one cell a conflict resolution procedure is applied , and then a simultaneous transition of all particles is made .
in our case the _ preliminary step _ includes calculations of sff @xmath3 .
each cell @xmath4 saves shortest discreet distance to the nearest exit .
the unit of such distance is a number of steps . to calculate the field @xmath3 ( and only here )
we admit diagonal transitions and consider that a vertical and horizontal movement to the nearest cell has a length of @xmath13 ; a length of a diagonal movement to the nearest cell is @xmath14 .
( it s clear that movement through a corner of walls or collums is forbidden and around movement is admitted in such cases only . )
it is made a discreet distance more close to continuous one .
probabilities to move from cell @xmath5 to each of four the nearest cells are calculated in the following way : @xmath15 where @xmath16 .
moreover @xmath17 only if @xmath18 correspondingly . a probability to stay at present cell is nt calculated directly . but
decision rules are organized in a way that such opportunity may be realized , and a people patience is reproduced by this means .
* decisions rules * are the following @xcite : 1 .
if @xmath19 then motion is forbidden , otherwise a target cell @xmath20 is chosen randomly using the transition probabilities
. 2 . 1 . if @xmath21 and @xmath22 then a target cell @xmath20 is fixed .
2 . if @xmath21 and @xmath23 then the cell @xmath20 is not available for moving and a `` people patience '' can be realized . to do it probabilities of the cell @xmath20 and all other
occupied the nearest neighbors are given to an opportunity not to leave the present position .
a target cell is randomly chosen again among empty neighbors and the present position .
3 . whenever two or more pedestrians have the same target cell , the movement of all involved pedestrians is denied with the probability @xmath24 , i.e. all pedestrians remain at their places @xcite .
one of the candidates moves to the desired cell with the probability @xmath25 .
a pedestrian that is allowed to move is chosen randomly .
pedestrians that are allowed to move perform their motion to the target cell .
pedestrians that stand in exit cells are removed from the room .
these rules are applied to all particles at the same time ; i.e. , parallel update is used . mostly in this paper we focus on transition probabilities . in normal situations
people choose their route carefully ( see @xcite and reference therein ) .
pedestrians keep a certain distance from other people and obstacles .
the more hurried a pedestrian is and the more tight crowd is the more smaller this distance is .
while moving people follow at least two strategies the shortest path and the shortest time . in ff models people move to the nearest exit , and their wish to move there does nt depend on a current distance to the exit .
from the probability view point this means that for each particle among all the nearest neighbor cells a neighbor with the smallest @xmath3 should have the largest probability .
so a main driving force for each pedestrian is to minimize sff @xmath3 at each time step .
but in this case only a strategy of the shortest path is mainly realized , and a slight regard to an avoidance of congestions is supposed .
this is not realistic for people movement .
an idea to improve a dynamics in a ff model is to introduce an environment analyzer in a probability formula .
it should decrease an influence of a short path strategy and increase the possibility to move to a direction with favorable conditions for a moving .
this will provide some kind of `` trade off '' between two main strategies . in this paper
we introduce a revised idea of the environment analyzer @xcite and make an attempt to mathematically formalize a complex decision making process that people do choosing their path while moving their strategies may vary : cooperate , coincide and compete depending on a current position and an environment ; i.e. , depending on a place and time .
at first let us present a probability formula and later we are discussing it in details .
for example , the transition probability to move from a cell @xmath5 to the up neighbor is : @xmath26 here * @xmath27 the main driven force : 1 .
@xmath28 ; 2 .
@xmath29 a sensitivity parameter ( model parameter ) that can be interpreted as the knowledge of the shortest way to the destination point , or as a wish to move to the destination point .
@xmath30 means that pedestrians do nt use information from the sff @xmath3 and move randomly .
the higher @xmath31 is the more directed is movement of pedestrians . +
as far as , sff depict direct distance from each cell to the nearest exit then @xmath32 if cell @xmath33 is closer to exit than current the cell @xmath5 . @xmath34
if the current cell is closer . and
@xmath35 if cells @xmath5 and @xmath33 are equidistant to the exit .
+ in contrast to other authors that deal with the ff model ( e.g. , @xcite , @xcite , @xcite , @xcite ) and use pure values of the field @xmath3 in the probability formula we propose to use only @xmath36 . from a mathematical view point
it is the same but computationally this trick has a great advantage .
values of sff may be too high ( it depends on a size of the space ) , and @xmath37 is uncomputable .
this is a significant restriction of that models .
at the same time @xmath38 , and problem of computing @xmath39 is absent ; * @xmath40 a factor that takes into account a people density in the direction : 1 .
@xmath41 a distance to a the nearest obstacle in this direction ( @xmath42 ) ; 2 . @xmath43 a `` visibility '' radius ( a model parameter ) is a maximal distance ( number of cells ) at which the pedestrian can look through to collect information about the density and possible obstacles ( but not pedestrians ) ; 3 .
density @xmath44 , if all @xmath45 cells are empty in this direction then @xmath46 , if all @xmath45 cells are occupied by people in this direction then @xmath47 .
we estimate density by using idea of the kernel rosenblat - parzen s @xcite density estimate , and @xmath48 were @xmath49 @xmath50 ; 4 .
@xmath51 a people sensitivity parameter ( a model parameter ) determines an influence of the people density .
the higher @xmath52 is the more pronounced is the strategy of the shortest path .
* @xmath53 a factor that takes into account walls and obstacles : 1 .
@xmath54 a wall sensitivity parameter ( a model parameter ) determines an influence of walls and obstacles ; 2 .
@xmath55 , + @xmath56 + an idea of the function @xmath57 goes from a fact that people avoid obstacles only moving towards a destination point .
but if people take detours ( that means not minimizing the sff ) approaching to obstacles is not avoiding . * note that only walls and obstacles turn the probability to `` zero '' .
probabilities to move from cell @xmath5 to each of four neighbors are : @xmath58(1-w_{i-1,j});\end{gathered}\ ] ] @xmath59(1-w_{i , j+1});\end{gathered}\ ] ] @xmath60(1-w_{i+1,j});\end{gathered}\ ] ] @xmath61(1-w_{i , j-1});\end{gathered}\ ] ] in - a product @xmath62 is the environment analyzer that deals with people and walls .
parameters @xmath52 and @xmath63 allow to tune sensitivity of the model to the people density and the approaching to obstacles correspondingly . and as far as @xmath64 , @xmath65 and @xmath66 both parameters should nt be less then @xmath31 . the term @xmath67 is only to avoid obstacles ahead , we will not discuss it here and let @xmath68 .
the following the shortest path strategy means to take detours around high density regions if it is possible .
the term @xmath69 works as a reduction of the main driving force ( that provides the shortest path strategy ) , and probability of detours becomes higher .
the higher @xmath51 is the more pronounced the shortest time strategy is .
note that the low people density makes influence of @xmath69 small , and the probability of the shortest path strategy increases for the particle .
here we present some simulation results to demonstrate that our idea works .
we use one space and compare 2 sets of parameters .
size of space is @xmath70 ( @xmath71 cells @xmath72 @xmath73 cells ) with one exit ( @xmath74 ) .
recall that the space is sampled into cells of size @xmath0 which can either be empty or occupied by one pedestrian only .
the static field @xmath3 is presented in fig .
2a . in fig .
2b are stating positions of particles .
they move towards exit with @xmath75 .
here we do nt present some quantity results and only demonstrate a quality difference of the flow dynamics for 2 sets of model parameters for the model presented .
the first set of parameters is @xmath76 , @xmath77 , @xmath78 .
the second set is @xmath76 , @xmath79 , @xmath78 .
a following moving condition are reproduced by both sets pedestrians know a way to the exit very well , they want go to the exit ( it is determined by @xmath31 ) , a visibility is good ( @xmath80 ) , attitude to walls is `` loyal '' ( @xmath68 ) .
only one parameter varies here , it s @xmath52 . in the first case ( @xmath77 ) a prevailing moving strategy is the shortest path . fig .
3 presents an evacuation in different moments for this case .
+ , @xmath78 , @xmath77.,title="fig : " ] , @xmath78 , @xmath77.,title="fig : " ] , @xmath78 , @xmath77.,title="fig : " ] + + , @xmath78 , @xmath77.,title="fig : " ] , @xmath78 , @xmath77.,title="fig : " ] , @xmath78 , @xmath77.,title="fig : " ] + the other set of parameters @xmath76 , @xmath79 , @xmath78 ( see fig . 4 ) allows to realize both strategies depending on conditions .
recall that the term @xmath69 in - works only if the people density @xmath81 , and it reduces the probability of the shortest path strategy depending on density s value . + , @xmath78 , @xmath79.,title="fig : " ] , @xmath78 , @xmath79.,title="fig : " ] , @xmath78 , @xmath79.,title="fig : " ] + + , @xmath78 , @xmath79.,title="fig : " ] , @xmath78 , @xmath79.,title="fig : " ] , @xmath78 , @xmath79.,title="fig : " ] +
figures 3 - 4 show a great difference in the flow dynamics that obtained by following only one movement strategy and by `` keeping in mind '' both strategies at a time .
the case of @xmath79 , i.e. , when both strategies of the shortest path and the shortest time are well pronounced , gives a more realistic shape of flow .
a model dynamics proper needs a careful investigation and it is go on .
a necessity of the @xmath52 spatial adaptation is already clear .
d. helbing , _ traffic related self - driven many - particle systems .
_ 1em plus 0.5em minus 0.4emrev .
phys . * 73 * , 4 , 2001 , 1067 - 1141 .
k. nishinari , a. kirchner ; a. namazi ; a. schadschneider .
_ extended floor field ca model for evacuation dynamics .
_ 1em plus 0.5em minus 0.4emieice trans.inf . & syst.e87-d,2004 , 726 .
e. kirik , t. yurgelyan , d. krouglov .
_ an intelligent floor field cellular automation model for pedestrian dynamics .
_ 1em plus 0.5em minus 0.4em proceedings of the summer computer simulation conference 2007 , the mission valley marriott san diego , california , 2007 , 10311036 .
( http://arxiv.org/abs/0906.2707v1 ) c. m. henein , t. white .
_ macroscopic effects of microscopic forces between agents in crowd models .
_ 1em plus 0.5em minus 0.4emphysica a , 373 , 2007 , 694718 .
d. yanagisawa , k. nishinari .
_ mean - field theory for pedestrian outflow through an exit .
_ 1em plus 0.5em minus 0.4emphysical review , e 76 , 2007 , 061117 .
e. parzen .
_ on estimation of probability density function .
_ 1em plus 0.5em minus 0.4em ann.math .
vol.33 , 1962 , 10651076 .
a. schadschneider , a. seyfried .
_ validation of ca models of pedestrian dynamics with fundamental diagrams .
_ 1em plus 0.5em minus 0.4emcybernetics and systems , vol .
40 ( 5 ) , 2009 , 367389 . | this paper deals with a mathematical model of a pedestrian movement . a stochastic cellular automata ( ca ) approach is used here . the floor field ( ff )
model is a basis model .
ff models imply that virtual people follow the shortest path strategy .
but people are followed by a strategy of the shortest time as well .
this paper is focused on how to mathematically formalize and implement to a model these features of the pedestrian movement .
some results of a simulation are presented .
cellular automata ; pedestrian dynamics ; transition probabilities ; artificial intelligence |
with the first polarized @xmath1+@xmath1 collisions at @xmath3 = 200 gev at the relativistic heavy ion collider ( rhic ) , a large single transverse spin asymmetry ( @xmath0 ) for neutron production in very forward kinematics was discovered by a polarimeter development experiment @xcite . that experiment was designed to measure the asymmetry for very forward photons and used an electromagnetic calorimeter .
the calorimeter was used to identify neutrons , originally to remove them from the photon data , when a large asymmetry was observed in forward neutrons .
the neutron energy resolution was coarse , so no cross section measurement was reported .
the discovery inspired the phenix experiment to use existing very forward hadronic calorimeters , with additional shower maximum detectors , to measure the neutron transverse asymmetry at the phenix interaction point at rhic with a significantly better neutron energy resolution .
here we report the first measurements of very forward inclusive and semi - inclusive neutron production cross sections at @xmath3 = 200 gev and measurements of @xmath0 for forward and backward production with improved neutron energy resolution .
the @xmath0 is a left
right asymmetry written as : @xmath7 for yields observed to the left when facing along the polarized proton s momentum vector , where @xmath8 ( @xmath9 ) is the production cross section when the protons are polarized up ( down ) .
the @xmath0 with cross section measurements for higher energy @xmath1@xmath2@xmath1 collisions provide qualitatively new information toward an understanding of the production mechanism .
, for the reggeon exchange model shown with lorentz invariant variables @xmath10 and @xmath11 .
`` @xmath12 '' is a proton or positron for @xmath1@xmath2@xmath1 or @xmath13 reactions .
@xmath14 indicates a regge trajectory with isospin odd such as @xmath15 , @xmath16 , @xmath17 and pomeron-@xmath15 in the regge theory . for pion exchange , @xmath14 = @xmath15 .
] cross sections of inclusive neutron production in unpolarized @xmath1@xmath2@xmath1 collisions were measured at the isr from @xmath3 = 30.6 to 62.7 gev @xcite .
these cross sections have been described using one pion exchange ( ope ) models @xcite . in ope
, the incoming proton emits a pion which scatters on the other proton as shown in figure [ fig_i_1 ] .
kinematics of the neutron are characterized by two variables , @xmath4 and @xmath18 defined by , @xmath19 where @xmath20 is the momentum component of the neutron in the proton - beam direction , @xmath21 and @xmath22 are energies of the neutron and the proton beam , and @xmath23 is the polar angle of the neutron from the beam direction which is very small ( @xmath24mrad ) for forward neutron production .
the measured cross section showed a peak around @xmath25 and was found to have almost no @xmath3 dependence .
ope models gave a reasonable description of the data .
ope models were also used to describe proton and photon induced production of neutrons measured at the hera @xmath5 collider @xcite .
these measurements probe the pion structure function at small @xmath26 .
the na49 collaboration also published the cross section for forward neutron production for @xmath1@xmath2@xmath1 collisions at @xmath3 = 17.3 gev @xcite .
they compared the result with those from isr and hera and found they did not agree .
the neutron asymmetry provides a new tool to probe the production mechanism . for the ope model
, @xmath0 arises from an interference between spin - flip and spin - nonflip amplitudes .
since the pion - exchange amplitude is fully spin - flip , the asymmetry is sensitive to other reggeon exchange amplitudes which are spin - nonflip , even for small amplitudes .
this paper presents the @xmath27 dependence of cross sections , inclusive and semi - inclusive ( with a beam - beam interaction requirement ) , and @xmath0 for very forward and very backward neutron production in polarized @xmath1@xmath2@xmath1 collisions at @xmath3 = 200 gev .
a plan view of the experimental setup for very forward neutron measurement at phenix @xcite is shown in fig . [ fig_e_1 ] .
the rhic polarized proton beams were vertically polarized .
each collider ring of rhic was filled with up to 111 bunches in a 120 bunch pattern , spaced 106 ns apart , with predetermined patterns of polarization signs for the bunches .
the colliding beam rotating clockwise when viewed from above is referred to as the `` blue beam '' and the beam rotating counterclockwise , the `` yellow beam '' .
neutrons were measured by a zero - degree calorimeter ( zdc ) @xcite with a position - sensitive shower - maximum detector ( smd ) .
one zdc module is composed of cu - w alloy absorbers with pmma - based communication grade optical fibers , and corresponds to 1.7 nuclear interaction lengths .
a single photomultiplier collects erenkov light via optical fibers .
three zdc modules are located in series ( 5.1 nuclear interaction lengths ) at @xmath281800 cm away from the collision point , covering 10 cm in the transverse plane .
the smd comprises @xmath26-@xmath29 scintillator strip hodoscopes and is inserted between the first and second zdc modules ( see fig . 5 of @xcite ) at approximately the depth of the maximum of the hadronic shower .
the @xmath26-coordinate ( horizontal ) is given by 7 scintillator strips of 15 mm width , while the @xmath29-coordinate ( vertical ) is given by 8 strips of 20 mm width , tilted by 45 degrees .
the neutron position can be reconstructed from the energy deposited in scintillators with the centroid method .
we calculated the centroid : @xmath30 where @xmath31 and @xmath32 are the energy deposit and the position of the @xmath33-th scintillator , respectively .
the number of scintillators with pulse height above the minimum ionization particle ( mip ) peak is shown as @xmath34 which is defined as the smd multiplicity .
detectors are located downstream of the rhic dipole ( dx ) magnet , so that collision - related charged particles are swept out .
a forward scintillation counter , with dimensions 10@xmath3512 cm , was installed in front of the zdc to remove charged particle backgrounds from other sources . in this analysis , we used only the south zdc detector , which is facing the yellow beam . as a beam luminosity monitor , beam beam counters ( bbcs ) are used .
the bbc comprises 64 photomultiplier tubes and 3 cm thick quartz erenkov radiators .
the two bbcs are mounted around the beam pipe @xmath28144 cm away from the collision point which cover @xmath28(3.03.9 ) in pseudorapidity and @xmath36 in azimuth .
the neutron data were collected in 2006 with two triggers .
one is the zdc trigger for neutron inclusive measurements , requiring an energy deposit in the south zdc greater than 5 gev .
the other trigger was a zdc@xmath37bbc trigger , a coincidence trigger of the zdc trigger with bbc hits which are defined as one or more charged particles in both of the bbc detectors .
we note that the zdc trigger was prescaled due to data acquisition limitations .
therefore , the zdc trigger samples are significantly smaller than the zdc@xmath37bbc trigger samples . in order to evaluate the detector performance ,
simulation studies were performed with geant3 with gheisha @xcite which simulated the response of the prototype zdc to hadrons well . a single neutron event generator and pythia ( version 6.220 ) @xcite were used to generate events .
the single neutron event generator simulated neutrons as a function of @xmath27 and @xmath38 .
the @xmath4 distribution which was used for the simulation input was determined as a differential cross section , @xmath39 , in the cross section analysis ( section [ sec_ax_1 ] ) .
the @xmath18 distribution is difficult to determine by the phenix data alone since the position and energy resolutions are insufficient to adequately determine it , so the @xmath18 distribution from the isr result , exp(@xmath404.8 @xmath18 ( gev/@xmath41 ) ) , was used as simulation input , assuming @xmath18 scaling from the isr to the phenix energies . to check the reliability of this assumption ,
distributions of radial distance from the detector center , @xmath42 , for the data and simulation were compared based on the relation of @xmath43 as , @xmath44 where @xmath45 is the distance from the collision point to the detector , corresponding to 1800 cm , and @xmath42 is determined for the shower centroid with eq .
( [ eq_e_1 ] ) .
the comparison of @xmath42 distributions with the integration of measured zdc energies 20120 gev agreed well as shown in fig .
[ fig_m_2:2 ] .
distributions for the data and simulation with the exponential @xmath18 shape .
distributions agreed within @xmath42@xmath464 cm . ]
the neutron energy measurement with the zdc was degraded by a nonlinearity of the photoelectron yield and shower leakage out the back and sides of the detector ( edge effect ) .
the zdc response was studied by simulation with the single neutron event generator .
the energy linearity and resolution were evaluated from the response to incident neutrons with energies from 20 to 100 gev in the simulation .
the absolute scale was normalized at 100 gev with the experimental data .
the zdc response below 100 gev exhibits nonlinear behavior as shown in fig .
[ fig_e_1_5 ] .
we applied a correction of the nonlinearity to the experimental data based on this result .
we used the difference between the linear and nonlinear response as a component of the systematic uncertainty in the determination of the cross section ( section [ sec_ax_1 ] ) .
( gev@xmath47 ) .
solid line shows the fit result ; @xmath48 = 65%/@xmath49 + 15% . ] as shown in fig .
[ fig_e_1_5 ] , the energy resolution for 20100 gev neutrons was described by @xmath50 the absolute scale of the energy measurement was normalized with the 100 gev single neutron peak in heavy ion collisions . however , the energy of neutrons from @xmath1@xmath2@xmath1 collisions was below 100 gev , so simulation was used to estimate the detector response for neutron energies in this region .
figure [ fig_e_2 ] shows the absolute energy scale calibrated by observing one neutron from peripheral cu+cu collisions at @xmath51 = 200 gev ; 100 gev neutrons less than 2 mrad from the beam axis produced the single neutron peak .
the energy resolution expected from simulation was about 22% for the 100 gev neutron and was consistent with the observed width of the single neutron peak as shown in fig .
[ fig_e_2 ] .
the energy nonlinearity was confirmed by the single neutron peak from cu+cu collisions at @xmath51 = 62.4 gev shown in fig .
[ fig_e_3 ] which peaked at [email protected] gev , consistent with nonlinearity indicated by the simulation .
= 200 gev .
peripheral events were selected by requiring bbc inactivity . ]
= 62.4 gev .
the neutron peak position was determined with a gaussian + polynomial fit . ]
the edge effect was studied by a prototype zdc with a 100 gev proton beam at cern . generally ,
the measured energy decreased near the edge , however , nearest the pmt , the measured energy increased .
this was found to be caused by the fibers in the top region which connected to the pmt ( see fig . 5 of @xcite ) ; where the shower hit the fibers directly .
the simulation used to study the prototype reproduced this effect .
a residual edge effect was seen in the data at the top and bottom of the detector , so we chose to apply a fiducial cut to minimize the effect .
according to the simulation , 95100% of the incident energy was contained within @xmath52 3 cm .
the position resolutions were evaluated by the simulation .
figure [ fig_m_7 ] shows the position resolution ( rms ) as a function of the neutron incident energy for @xmath26 ( horizontal ) and @xmath29 ( vertical ) positions .
the position resolution was approximately 1 cm for the neutron energy at 100 gev .
( top ) and @xmath29 ( bottom ) .
circles show measured values .
they were well reproduced by a second order polynomial fit .
red lines show the fit results . ] near the edge of the detector , the position measurement is also affected by shower leakage .
if the incident position was in the edge area , the output position was shifted to the detector center due to shower leakage , independent of neutron energy .
this position shift caused by the edge effect is corrected based on the simulation .
the reliability of the position measurement was studied by comparing hadron shower shapes of the data and simulation .
the shower width and highest shower fraction among all scintillators were calculated for @xmath26 and @xmath29 independently .
we compared the measured distribution with simulation for each smd multiplicity since the hadron shower shape sensitively depends on the smd multiplicity .
the distribution of @xmath29 was well reproduced by the simulation , however the distribution of @xmath26 was not well reproduced , especially for the highest shower fraction in high smd multiplicity events .
the systematic uncertainties for the position measurement were estimated by matching the highest shower fraction of @xmath26 by smearing the simulated shower shapes in case of the smd multiplicity = 7 , which shows the worst agreement between the data and simulation .
after the smearing to match the highest shower fraction , the shower width of the simulation also reproduced that of the experimental data .
the position resolution increased 14% after the smearing .
events within the detector acceptance in @xmath1@xmath2@xmath1 collisions were studied with geant3 with pythia event generators , and the performance of neutron identification and its reliability were evaluated .
we studied particle species detected in the zdc with the 5 gev energy threshold which was required for the zdc trigger ( without the bbc coincidence requirement ) . in about 92% of events , only a single particle was detected by the zdc in each @xmath1@xmath2@xmath1 collision , mainly photons , neutrons and protons .
energy distributions for these three particles are plotted in fig .
[ fig_m_19 ] .
@xmath2@xmath1 collision are shown . ] only neutral particles , photons and neutrons , were expected to be detected with the zdc due to sweeping of charged particles by the dx magnet .
however scattered protons could hit the dx magnet or beam pipe and create a hadronic shower and particles from the shower could hit the zdc .
most of the photons and neutrons were generated by diffractive and gluon scattering processes . in pythia hard processes , neutrons are generated mainly from string fragmentation ( @xmath2465% ) and then decay from @xmath53 .
the forward photons were generated by decays of @xmath54s ( @xmath2491% ) and @xmath55s ( @xmath247% ) .
protons were generated by elastic and diffractive processes .
particles depositing less than 20 gev of energy in the zdc were predominantly photons and protons as shown in fig .
[ fig_m_19 ] .
photons are mostly absorbed in the first zdc module , which is 51 radiation lengths long .
thus , photons were removed by requiring energy deposited in the smd or in the second zdc module . in photon
rejection with the smd , more than one scintillator above threshold ( the smd multiplicity @xmath56 2 ) were required for both @xmath26 and @xmath29 . after applying this cut , the neutron purity was estimated to be [email protected]% .
in photon rejection with the second zdc module , energy deposited in the second zdc module above 20 gev was required . after applying this cut ,
the neutron purity was estimated to be [email protected]% . in the analyses of the cross section and the asymmetry , photon rejection with the smd was applied since the position information calculated by the smd was required .
rejection with the second zdc was used for the estimation of the rejection efficiency with the smd which is discussed in section [ sec_ax_1 ] .
the charge veto counter was used to reject protons . a neutron energy above 20 gev and the charge veto cut removed most proton events , as discussed later in this section .
the main backgrounds after neutron identification are @xmath57s and protons .
the purities were estimated for neutron energies above 20 gev . in the cross section and the asymmetry analyses
, we also required the acceptance cut and/or a higher energy cut . in these cases ,
the purities improve and are estimated in each analysis section . in the isr experiment ,
the @xmath57 contamination to the neutron measurement was estimated from the @xmath58 measurements @xcite .
they obtained 10 % contamination at @xmath4=0.2 and less than 4 % at @xmath590.4 .
the fraction of @xmath57 to neutron in pythia is consistent with the isr result .
we have included no correction for the @xmath60 contamination in this analysis .
the proton background is very sensitive to the materials around the zdc and the magnet tuning in the accelerator .
the systematic uncertainty of proton contamination was estimated by the simulation using the measured fraction of charged events in the charge veto counter .
noise was estimated by the pedestal width of the data and was incorporated into the simulation . for the proton contamination analysis ,
photon events were removed by requiring the second zdc module cut .
the fraction of proton events can be estimated as a fraction of charged candidates , which are the events with one more mips in the charge veto counter .
these fractions were 0.42 and 0.28 for the data and simulation , respectively .
proton events in the experimental data were about 1.5 times more frequent than that of the simulation .
we ascribe the difference to beam conditions that cause interactions with materials around the dx magnet and the zdc .
the threshold dependence of the selection of charged particle candidates was also studied .
the change in charged particle fraction was less than 1% so that the threshold dependence was negligibly small .
therefore , the factor 1.5 was a reasonable estimate for the fraction of charged candidates between the data and simulation .
the proton background was estimated and included in the systematic uncertainties . according to the simulation study for the structure of proton events ,
proton events should be detected in the direction of beam bending which is negative @xmath26 for the south zdc .
this behavior was confirmed by the experimental data as shown in fig .
[ fig_m_21:2 ] which is a plot of the @xmath26 position determined by the smd @xmath61 the charge distribution in the charge veto counter .
most charged candidates were distributed in the negative @xmath26 region .
we assumed the proton background @xmath0 equals zero and evaluated its systematic uncertainty by the dilution method with @xmath62=0 in the asymmetry analysis .
position calculated by the smd @xmath61 the charge distribution in the charge veto counter for the experimental data .
most charged events were distributed in the negative @xmath26 region which is the direction of beam bending by the dx magnet . ]
the differential cross section with respect to @xmath4 was measured : @xmath63 where @xmath64 is the number of neutrons after the correction of cut efficiencies and the energy unfolding . for the cross section analysis ,
6.5 million events taken by the zdc trigger were used from the sampled luminosity of 240 nb@xmath65 .
the acceptance cut @xmath42@xmath462 cm was used to select kinematics similar to the isr experiment .
we assumed the beam axis was the same as the zdc center in this analysis and the deviation was evaluated as a systematic uncertainty .
the beam axis compared to the zdc center is discussed in appendix a. @xmath462 cm , corresponds to @[email protected] gev/@xmath41 ) . ]
figure [ fig_ax_1 ] shows the energy distribution measured with the zdc after the neutron identification and the acceptance cut .
the energy spectrum was peaked at about 70 gev , and this was used for a stability check of the zdc gain run by run , which was found to be stable .
the ratio of the neutron yield to the bbc counts without the collision vertex requirement was used for a stability check of the neutron selection , and it was also found to be stable .
one background source was beam - gas interaction .
beam - gas events are normally removed by requiring a forward - backward coincidence of the bbc detectors . however ,
this could not be done for the zdc triggered events .
instead , we evaluated the fraction of beam - gas background using the 9 noncolliding bunch crossings with the combination of filled and empty bunches at phenix .
we found that the fraction was [email protected] on average , negligibly small .
the neutron hit position was calculated by the centroid method using the distribution of scintillator charge above the threshold in the smd , eq .
( [ eq_e_1 ] ) . in this analysis ,
the same threshold was applied to the data and simulation and the efficiency of the smd cut was estimated by simulation .
the difference of efficiencies caused by uncertainty of the smd cut efficiency was estimated using the nearly pure neutron sample by the neutron identification with the second zdc cut ( section [ sec_m_9 ] ) .
the energy spectrum was corrected based on the smd cut efficiency before the energy unfolding .
the measured neutron energy with the zdc is smeared by the energy resolution . to extract the initial energy distribution ,
it is necessary to unfold the measured energy distribution .
the energy unfolding method is described in appendix b. the zdc energy response to neutrons below 100 gev was found by the simulation to be nonlinear as described in section [ sec_m_3 ] .
this nonlinearity was included in the transition matrix @xmath66 of appendix b , and corrected by the energy unfolding . since the hadronic interaction
could only be determined from simulation , a systematic uncertainty was included , using the variation of the cross section evaluated with a different matrix @xmath66 with a linear response .
the efficiency of the experimental cuts , including the neutron identification and the acceptance cut , for the unfolded @xmath4 distribution was estimated by the simulation with the single neutron event generator .
the acceptance cut used the radius , @xmath42 , and the efficiency was evaluated from the @xmath18 distribution based on eq .
( [ eq_i_3 ] ) : @xmath67 gev/@xmath41 . for the @xmath18 distribution , we used two distributions : a gaussian form @xmath68 , where @xmath69 was obtained by hera @xcite with error evaluation , and an exponential form @xmath70 , where @xmath71 ( gev@xmath72)@xmath65 which was used in the isr analysis @xcite .
the simulated @xmath18 distributions with those two input distribution were compared with experimental data normalized to the same total entries .
it was found that the differences between data and those two inputs were not large as shown in fig .
[ fig_ptdist ] .
distribution from experimental data ( black closed circles ) and two simulations using gaussian form ( blue open squares ) and exponential form ( red open circles ) inputs . ]
figure [ fig_ax_10 ] shows the simulated @xmath18 distributions ( dashed line ) in each @xmath4 bin .
the geometrical maximum @xmath18 for the acceptance cut , @xmath73 cm , in each @xmath4 are given by @xmath74 gev/@xmath41 , shown as dot - dashed vertical lines .
the actual @xmath18 distributions with the experimental cuts were smeared due to the position resolution and the energy resolution , shown as solid lines .
ratios of these counts are the efficiency for the experimental cuts , and are listed in table [ tab_ax_2 ] .
the errors were derived considering the uncertainty in the parameter @xmath69 in the gaussian form evaluated by hera .
there is no significant difference in the result in case of using the isr ( exponential ) @xmath18 distribution .
distributions using the gaussian @xmath18 shape .
initial @xmath18 distributions are shown as dashed lines in each @xmath4 region .
the expected @xmath18 region for the acceptance , @xmath73 cm , is below the vertical dot - dashed lines , which are the maximum @xmath18 calculated as @xmath75 gev/@xmath41 .
the actual @xmath18 distributions with the experimental cuts are shown as solid lines . ] .
the expected @xmath18 for @xmath522 cm , mean @xmath18 value with the experimental cut , and the efficiency for the experimental cut estimated by the simulation ( fig .
[ fig_ax_10 ] ) .
the errors were derived considering the uncertainty in the parameter @xmath69 in the gaussian form evaluated by hera . [ cols="<,^,^ " , ] [ tab_re_5 ] dependence of @xmath0 for neutron production in the zdc trigger sample ( top ) and for the zdc@xmath37bbc trigger sample ( bottom ) .
the error bars show statistical uncertainties and brackets show @xmath18-correlated systematic uncertainties .
systematic scale uncertainties listed in table [ table : syserr_an ] and polarization scale uncertainties are not included . ]
the @xmath27 dependence of @xmath0 for production is listed in table [ tab_re_4 ] and [ tab_re_5 ] , and plotted in fig .
[ fig_re_4 ] .
the @xmath76 data were fitted with a sine curve , eq.([eq_ip_3:3 ] ) , to obtain @xmath0 with @xmath77 .
the mean @xmath4 values were determined according to section [ sec_aa_1 ] .
statistical uncertainties are shown as error bars and @xmath18-correlated systematic uncertainties are shown as brackets .
scale uncertainties from the asymmetry measurements and the beam polarization are not included .
we observe significant negative @xmath0 for neutron production in the positive @xmath4 region and with no energy dependence within the uncertainties , both for inclusive neutron production and for production including a beam - beam interaction requirement .
no significant backward neutron production asymmetry is observed .
the measurement of the cross section for the @xmath1@xmath2@xmath1 production of neutrons at @xmath3=200 gev has been presented here , and it is consistent with @xmath4 scaling when compared to isr results .
these cross sections are described by the ope model in regge calculus @xcite .
therefore , the observed large asymmetry for neutron production at rhic , as presented in @xcite and here , may arise from the interference between a spin - flip amplitude due to the pion exchange and nonflip amplitudes from other reggeon exchanges .
so far our knowledge of reggeon exchange components for neutron production is limited to the pion . under the ope interpretation , the asymmetry has sensitivity to the contribution of all spin nonflip reggeon exchanges , even if the amplitudes are small .
recently kopeliovich _ et al .
_ calculated the @xmath0 of forward neutron production from the interference of pion and reggeon exchanges , and the results were in good agreement with the phenix data @xcite
. we can also discuss our results based on the meson - cloud model @xcite .
this model gives a good description for the result from a drell - yan experiment at fnal , e866@xcite .
in this model , the drell - yan process is generated by the interaction between the @xmath45 quark in one proton and the @xmath78 quark in the @xmath79 of @xmath80 state for other proton . in this model
the neutron should be generated with very forward kinematics , possibly similar to the kinematics of the results presented here .
the meson - cloud model was successfully applied to neutron production in the isr experiment @xcite and we expect it is applicable to our @xmath0 and cross section measurements for higher energy @xmath1@xmath2@xmath1 collisions .
we have measured the cross section and single transverse spin asymmetry , @xmath0 , for very forward neutron production in polarized @xmath1+@xmath1 collisions at @xmath3=200 gev .
the results from the phenix experiment at rhic were based on a zero degree hadronic calorimeter ( zdc ) augmented by a shower maximum detector , covering neutron production angles to @xmath23=2.2 mrad .
a large @xmath0 for neutron production had been observed in a polarimeter development experiment at rhic , using an electromagnetic calorimeter to identify neutrons , with coarse neutron energy resolution@xcite .
the phenix experiment then outfitted existing zdc detectors to act as polarimeters to monitor the beam polarizations and polarization directions at the experiment .
the results presented here are based on studies with the zdc polarimeter , which due to a much better measurement of the neutron energy , provide first measurements of the neutron production cross section at rhic energy , and the dependence of @xmath0 on the neutron energy .
the measured cross section is consistent with @xmath4 scaling from isr results . within uncertainties ,
the observed @xmath0 were consistent with the previous result at rhic @xcite and for @xmath81 ( the region measured by this experiment ) no significant @xmath4 dependence was observed .
we also present measured @xmath0 for neutrons produced backward from the polarized beam .
these results are consistent with zero .
the cross sections for large @xmath4 neutron production , as well as those in @xmath5 collisions at hera , are largely reproduced by a one pion exchange model ( ope ) . using this model , the observed large asymmetry for the neutron production
would be considered to come from the interference between a spin - flip amplitude due to the pion exchange and nonflip amplitudes from other reggeon exchanges .
on the basis of the ope model , the large neutron @xmath0 would have sensitivity to the contribution of other reggeon exchanges .
future measurements of neutron production cross sections and asymmetries will include analysis of rhic runs at @xmath3=62.4 gev and at 500 gev .
the measurements at different center of mass energies will probe the @xmath4 and @xmath18 dependence for neutron production at fixed , very forward production angles @xmath822.2 mrad .
we thank the staff of the collider - accelerator and physics departments at brookhaven national laboratory and the staff of the other phenix participating institutions for their vital contributions .
we acknowledge support from the office of nuclear physics in the office of science of the department of energy , the national science foundation , a sponsored research grant from renaissance technologies llc , abilene christian university research council , research foundation of suny , and dean of the college of arts and sciences , vanderbilt university ( u.s.a ) , ministry of education , culture , sports , science , and technology and the japan society for the promotion of science ( japan ) , conselho nacional de desenvolvimento cientfico e tecnolgico and fundao de amparo pesquisa do estado de so paulo ( brazil ) , natural science foundation of china ( p. r. china ) , ministry of education , youth and sports ( czech republic ) , centre national de la recherche scientifique , commissariat lnergie atomique , and institut national de physique nuclaire et de physique des particules ( france ) , bundesministerium fr bildung und forschung , deutscher akademischer austausch dienst , and alexander von humboldt stiftung ( germany ) , hungarian national science fund , otka ( hungary ) , department of atomic energy and department of science and technology ( india ) , israel science foundation ( israel ) , national research foundation and wcu program of the ministry education science and technology ( korea ) , ministry of education and science , russian academy of sciences , federal agency of atomic energy ( russia ) , vr and wallenberg foundation ( sweden ) , the u.s
. civilian research and development foundation for the independent states of the former soviet union , the us - hungarian fulbright foundation for educational exchange , and the us - israel binational science foundation .
the zdc center was aligned to the beam axis at the beginning of the 2003 run .
we assumed that the beam axis was on the zdc center in this analysis of 2005 data .
we used two approaches to estimate the beam and zdc alignment .
peripheral neutrons from a heavy ion run just prior to the polarized proton run gave centers of @xmath83 cm and @xmath84 cm at the south zdc .
the center of the asymmetry @xmath0 was also used to determine the center of the beam axis at the zdc , since @xmath0 must be zero at zero production angle .
we used the zdc@xmath37bbc trigger sample in this analysis .
the asymmetry was measured for a vertically polarized beam to obtain the center in @xmath26 , and for a special run with horizontally polarized beam to obtain the center in @xmath29 .
the results were @xmath85 cm and @xmath86 cm .
the results of the two techniques agreed reasonably for @xmath26 , and did not agree for @xmath29 . the beam axis shifts that we observed were considered as systematic uncertainties for the results .
the uncertainties were determined from variations of the cross section and asymmetry obtained by moving the center of acceptance while keeping the same cut region ( for example , @xmath42@xmath462 cm for the cross section analysis ) .
the measured neutron energy with the zdc is smeared by the energy resolution . for the extraction of the original energy distribution ,
it is necessary to unfold the measured energy distribution .
we use an unfolding method proposed in @xcite .
we assume that the initial distribution @xmath87 is smeared to the measured distribution @xmath88 and this smearing is described by a linear combination .
their relation can be given by a transition matrix @xmath89 as , @xmath90 or @xmath91 .
if the smearing effect is large , the result is very sensitive to a small change of @xmath66 .
it can be discussed using an orthogonal decomposition .
the matrix @xmath66 is diagonalized into @xmath92 with a transformation matrix @xmath93 , @xmath94 where @xmath95 , and @xmath96 and @xmath97 are new vectors transformed from @xmath98 and @xmath99 , respectively .
the diagonal elements of the matrix @xmath92 are the eigenvalues @xmath100 of the matrix @xmath66 .
each of the coefficients @xmath101 and @xmath102 in @xmath103 is transformed independently of any other coefficient by using eigenvalue @xmath104 , @xmath105 in order to perform the unfolding , the coefficients @xmath102 have been affected by statistical fluctuations of the elements of measured vector @xmath98 . the @xmath101 which includes the information of initial vector @xmath26 is obtained by @xmath106 . the statistical fluctuation of the @xmath102 amplified in the case of small eigenvalue @xmath104 , resulting in instability .
reasonable result can be obtained by cutting the @xmath102 which has a large statistical uncertainty .
first , the coefficients @xmath102 were calculated .
three sets of the transition matrix @xmath66 , which have the same energy resolution but different initial energy distributions , were prepared with a simulation to check the statistical error propagation of the @xmath102 .
initial shapes were prepared to increase , be flat and decrease as a function of @xmath4 .
these shapes are close to the cross sections at @xmath18 @xmath107 0.0 gev/@xmath41 , 0.2 gev/@xmath41 and 0.4 gev/@xmath41 in the isr results .
energy spectra before and after the unfolding are plotted in fig .
[ fig_ax_15 ] .
horizontal axis is changed to @xmath4 by eq .
( [ eq_i_2 ] ) .
n. n. nikolaev , w. schafer , a. szczurek , and j. speth , phys .
d * 60 * , 014004 ( 1999 ) .
u. dalesio and h. j. pirner , eur . phys . j. a * 7 * , 109 ( 2000 ) .
a. b. kaidalov , v. a. khoze , a. d. martin , and m. g. ryskin , eur .
j. c * 47 * , 385 ( 2006 ) .
a. bunyatyan and b. povh , eur .
phys . j. a * 27 * , 359 ( 2006 ) .
s. chekanov _ et al . _
( zeus collaboration ) , nucl .
b * 776 * , 1 ( 2007 ) .
f. d. aaron _ et al . _
( h1 collaboration ) , eur .
j. c * 68 * , 381 ( 2010 ) .
t. anticic _ et al . _
( na49 collaboration ) , eur .
j. c * 65 * , 9 ( 2010 ) .
k. adcox _ et al . _
( phenix collaboration ) , nucl . instrum .
a * 499 * , 469 ( 2003 ) .
c. adler , a. denisov , e. garcia , m. j. murray , h. strobele , and s. n. white , nucl .
instrum .
a * 470 * , 488 ( 2001 ) .
r. brun , f. carminati , and s. giani , `` geant detector description and simulation tool , '' cern - w5013 .
b. z. kopeliovich , i. k. potashnikova , i. schmidt , and j. soffer , phys .
d * 84 * , 114012 ( 2011 ) k. g. boreskov and a. b. kaidalov , eur . phys .
j. c * 10 * , 143 ( 1999 ) ; r. j. fries and a. schafer , phys .
b * 443 * , 40 ( 1998 ) . | the energy dependence of the single - transverse - spin asymmetry , @xmath0 , and the cross section for neutron production at very forward angles were measured in the phenix experiment at rhic for polarized @xmath1@xmath2@xmath1 collisions at @xmath3=200 gev .
the neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad .
we report results for neutrons with momentum fraction of @xmath4=0.45 to 1.0 .
the energy dependence of the measured cross sections were consistent with @xmath4 scaling , compared to measurements by an isr experiment which measured neutron production in unpolarized @xmath1@xmath2@xmath1 collisions at @xmath3=30.662.7 gev .
the cross sections for large @xmath4 neutron production for @xmath1@xmath2@xmath1 collisions , as well as those in @xmath5 collisions measured at hera , are described by a pion exchange mechanism .
the observed forward neutron asymmetries were large , reaching @xmath6 for @xmath4=0.8 ; the measured backward asymmetries , for negative @xmath4 , were consistent with zero .
the observed asymmetry for forward neutron production is discussed within the pion exchange framework , with interference between the spin - flip amplitude due to the pion exchange and nonflip amplitudes from all reggeon exchanges . within the pion exchange description ,
the measured neutron asymmetry is sensitive to the contribution of other reggeon exchanges even for small amplitudes . |
mammary glands are anatomical structures that distinguish mammals from all other animals and secrete milk for offspring . these organs are considered composite secretory organs and are made up of various types of cells , including epithelial cells , adipocytes , fibroblasts , and vascular endothelial cells ( macias & hinck , 2012 ) .
there are three major stages of mammary gland development : embryonic , pubertal , and reproductive stages . in embryonic mammary gland development ,
the epithelial placodes of ectoderm formation during early embryo development give rise to the mammary gland structures during morphogenesis ( pispa & thesleff , 2003 ) .
the placodes fundamentally regulate epithelial - mesenchymal interactions and generate the rudimentary ductal structure of the gland present at birth .
the puberty and reproductive stages of mammary gland development occur continuously through hormonal regulation associated with pubertal growth , pre gnancy , lactation , and involution . at birth ,
these small ducts can grow allometrically following the growth phase and undergo expansion , called ductal morphogenesis , until puberty .
puberty in mammals initiates morphogenesis of branched structures in the mammary gland ; this process is mutually regulated by growth hormone ( gh ) , estrogen , and insulin - like growth factor ( igf)- 1 to generate a ductal tree ( howlin et al . , 2006 ) .
during pregnancy , alveoli of the mammary glands , which secrete milk , are generated through combined action of progesterone and prolactin ( prl ) . in the mature structure
, short branched ducts are controlled by progesterone ; however , alveologenesis occurs only during pregnancy through induction by prl and progesterone .
when the levels of progesterone and prl increase in the serum , branched alveoli are developed , and adipose tissue and blood flow are increased . after achieving milk production ,
prl is decreased , and involution , defined as remodeling back to the original adult state , occurs . in bovines , colostrum is secreted during late gestation and for the first few days after calving . in this review , we will focus on the igf pathway and its role in developmental processes and involute interactions in bovine mammary glands components .
the igf pathway consists of three ligands ( igf - i , igfii , and insulin ) , their receptors ( igf - ir , igf - iir , and insulin receptor ) , high - affinity binding proteins ( igf binding protein [ igfbp ] 16 ) , and their specific proteases ( le roith , 2003 ) ; the complex interactions among these components maintain cellular mechanisms . as shown in fig .
1 , these igf ligands play various roles in mammalian growth , development , and metabolism and act as endocrine factors that prevent apoptotic signaling .
mammary epithelial cells are influenced by many components of the igf system , particularly igfbps .
the interactions between igfs and igfbps have been shown to inhibit igf - i or igf - ii binding with igf - ir and igf - iir through competitive mechanisms ( kelley et al . , 1996 ) .
bovine mammary epithelial cells have been reported to express all three igf receptors ( hadsell et al . , 1990 ) , to synthesize igfbps ( gibson et al . , 1999 ) , and to produced igf - ii ( baumrucker et al . , 1993 ) .
igf-1 mrna is expressed in mammary glands of pregnant and lactating cows ( glimm et al . , 1992 ; sharma et al . , 1994 ) , whereas cultured primary mammary gland cells do not exhibit igf-1 expression .
recent studies have suggested that igf - i plays a critical role in growth hormone ( gh)-induced mammary ductal growth .
the igf and gh interaction is important for regulation of mammalian epithelial cell proliferation and differentiation .
igf - i is circulated through its interaction with gh , which is the major inducer of alveolar growth ( kleinberg , 1997 ) .
there are correlations between igf - i and gh expression , and these correlations may directly mediate mammary growth ( ruan et al . , 1992 ) .
additionally , gh has been shown to induce igf - i expression in mammary tissue ( ruan et al . , 1995 ) .
furthermore , igf - i can promote ductal development in implanted mammary glands and synergizes with estrogen to support the generation of terminal end buds ( tebs ) and ductal elongation in ovariectomized mice ( ruan et al .
several studies have reported that igf - i and igfr interactions are associated with cell proliferation and apoptosis through inhibition of wnt signaling ( richard - parpaillon et al . , 2002 ; rota & wood , 2015 ) .
igf may specifically influence igf-1r owing to its greater binding affinity than igf - ii or insulin ( jones & clemmons , 1995 ) .
moreover , igf - iir binds more specifically to igf - ii than igf - i and does not bind with insulin ( massague et al . , 1982 ; rechler & nissley , 1985 ) . in general ,
mammary gland development is characterized by ductal growth in nonpregnant heifers . while igf - i is highly expressed during the early stages of mammogenesis when compared with that during lactation ,
this protein exhibits potential proliferative functions throughout the entire process of bovine mammary gland development .
additionally , igf-1r and gh receptor mrna expression levels are decreased during the lactation stage .
these decreases in mrna levels in bovine mammary tissue have been shown to be species specific ( plath - gabler et al . , 2001 ) .
different types of igf-1r transcripts have been discovered in bovine mammary glands ( glimm et al . , 1992 ) .
igfbps , which are encoded by six similar transcripts , are regulated based on their interactions with igfs and their specific binding proteins ( ballard et al .
igfbp bioactivity inhibits the functions of igf - i and igf - ii by competition with igf - ir and igf - iir through igf - i and igf - ii near the cell surface .
furthermore , igfs and igfbps can influence interactions with other growth pathways or igf - independent functions ( kelley et al .
the interactions between igfbps and igfs are regulated by proteases by affecting the binding affinity of igfbp for igfs .
modifications of igfbps , such as protein phosphorylation and binding with other factors , may affect their interactions with other proteins ( mccusker et al .
for example , when igfbp-1 binds to integrin , igfbp-3 binding at the cell surface is decreased because the specific affinity of igfbp-3 for igf-1 is reduced when igfbp-3 interacts with cell surface molecules ( conover & powell , 1991 )
. moreover , suppression of igf - i release from igfbp-3 may occur through the interaction between igfs and igfir , thus reducing the activity of igfs .
igfbp expression during mammary gland development has also been studied by analysis of the contributions of igfbp-2 and -5 to branching mammogenesis during pregnancy ( wood & yee , 2000 ) .
all igfbps exhibit high - affinity binding with igfs ; however , igfbps also have other functions independent of igfs . igfbp-1 and
-2 include the tripeptide arg - gly - asp ( rgd ) sequence , which is recognized by cell surface integrins and cell adhesion molecules .
igfbp-1 overexpression in chinese hamster cells increases cell migration ( jones et al . , 1993 ) .
additionally , igfbp-3 has independent effects on the modulation of bax and bcl-2 , inducing apoptosis in human breast cancer cells through igf - i ( butt et al . , 2000 ) and inhibiting proliferation in type i igf receptor - knockout mice ( valentinis et al . , 1995 ) .
recent studies have demonstrated that igfbp-3 regulates transforming growth factor ( tgf)- during programmed cell death through interactions between p53 and igf - independent signaling ( rajah et al . , 1997 ) .
additionally , the tgf- receptor can interact with igfbp-3 ( leal et al . , 1997 ) .
moreover , igfbp-5 has been shown to activate dna synthesis in osteoblasts through a pathway independent of igf - i ( andress , 1995 ) .
both igfbp-3 and -5 contain a putative nuclearlocalization sequence ( nls ) ( radulescu , 1994 ) and have been shown to be expressed in the nuclei using immunelogical localization methods ( jaques et al .
these results suggest that igfbps can also contribute to intracellular functions , such as proliferation , apoptosis , and cell migration .
thus , these observations also provide insights into whether the high concentrations of igfbp-5 in bovine milk interact with igf - dependent or -independent pathways . in human milk production , igfbp- 2
is more highly expressed than igfbp-1 and igfbp-3 ( erickson et al . , 1993 ; donovan & odle , 1994 ) , and igfbp-1 and igfbp-3 are present at lower concentrations than igfbp-2 in human milk .
mrnas encoding igfbp-2 and -3 are expressed in porcine mammary glands ( simmen et al . , 1988 ) .
thus , igfbp-2 and - 3 in milk is derived from the mammary glands . in bovine serum , igfbp-2 is highly expressed during the early lactation stage and decreased during the dry period ( vicini et al . , 1991 ) .
igfbp-2 is not expressed in maternal serum , but is expressed in lactating mammary glands , suggesting that igfbp-2 is synthesized in mammary glands .
igfbp-4 expression has been identified in rat mammary glands , although the concentration is lower than that in serum ( donovan et al . , 1995 ) . igfbp-5 and -6 are not present in milk during the lactation stage .
igfs and igfbps may enter milk from the serum by paracellular interactions and secretion by epithelial cells .
however , involuting mammary glands exhibit increased levels of igfbp-2 , igfbp-4 , and igfbp-5 mrnas .
igf-1 is a survival factor for several different types of cells and is regulated by gh ( travers et al . , 1996 ) .
of all the hormonal changes that occur during the involution stage , prl is able to influence only igfbp-5 synthesis , suggesting that the prolactin is a potential inhibitor of igfbp-5 .
the igf pathway consists of three ligands ( igf - i , igfii , and insulin ) , their receptors ( igf - ir , igf - iir , and insulin receptor ) , high - affinity binding proteins ( igf binding protein [ igfbp ] 16 ) , and their specific proteases ( le roith , 2003 ) ; the complex interactions among these components maintain cellular mechanisms . as shown in fig .
1 , these igf ligands play various roles in mammalian growth , development , and metabolism and act as endocrine factors that prevent apoptotic signaling .
mammary epithelial cells are influenced by many components of the igf system , particularly igfbps .
the interactions between igfs and igfbps have been shown to inhibit igf - i or igf - ii binding with igf - ir and igf - iir through competitive mechanisms ( kelley et al . , 1996 ) .
bovine mammary epithelial cells have been reported to express all three igf receptors ( hadsell et al . ,
1990 ) , to synthesize igfbps ( gibson et al . , 1999 ) , and to produced igf - ii ( baumrucker et al . , 1993 ) .
igf-1 mrna is expressed in mammary glands of pregnant and lactating cows ( glimm et al . , 1992 ; sharma et al . , 1994 ) , whereas cultured primary mammary gland cells do not exhibit igf-1 expression .
recent studies have suggested that igf - i plays a critical role in growth hormone ( gh)-induced mammary ductal growth .
the igf and gh interaction is important for regulation of mammalian epithelial cell proliferation and differentiation .
igf - i is circulated through its interaction with gh , which is the major inducer of alveolar growth ( kleinberg , 1997 ) .
there are correlations between igf - i and gh expression , and these correlations may directly mediate mammary growth ( ruan et al . , 1992 ) .
additionally , gh has been shown to induce igf - i expression in mammary tissue ( ruan et al . , 1995 ) .
furthermore , igf - i can promote ductal development in implanted mammary glands and synergizes with estrogen to support the generation of terminal end buds ( tebs ) and ductal elongation in ovariectomized mice ( ruan et al .
several studies have reported that igf - i and igfr interactions are associated with cell proliferation and apoptosis through inhibition of wnt signaling ( richard - parpaillon et al . , 2002 ; rota & wood , 2015 ) .
igf may specifically influence igf-1r owing to its greater binding affinity than igf - ii or insulin ( jones & clemmons , 1995 ) .
moreover , igf - iir binds more specifically to igf - ii than igf - i and does not bind with insulin ( massague et al . , 1982 ; rechler & nissley , 1985 ) .
in general , mammary gland development is characterized by ductal growth in nonpregnant heifers . while igf - i is highly expressed during the early stages of mammogenesis when compared with that during lactation ,
this protein exhibits potential proliferative functions throughout the entire process of bovine mammary gland development .
additionally , igf-1r and gh receptor mrna expression levels are decreased during the lactation stage .
these decreases in mrna levels in bovine mammary tissue have been shown to be species specific ( plath - gabler et al . , 2001 ) .
different types of igf-1r transcripts have been discovered in bovine mammary glands ( glimm et al . , 1992 ) .
igfbps , which are encoded by six similar transcripts , are regulated based on their interactions with igfs and their specific binding proteins ( ballard et al . , 1989 ) .
igfbp bioactivity inhibits the functions of igf - i and igf - ii by competition with igf - ir and igf - iir through igf - i and igf - ii near the cell surface .
furthermore , igfs and igfbps can influence interactions with other growth pathways or igf - independent functions ( kelley et al .
the interactions between igfbps and igfs are regulated by proteases by affecting the binding affinity of igfbp for igfs .
modifications of igfbps , such as protein phosphorylation and binding with other factors , may affect their interactions with other proteins ( mccusker et al .
for example , when igfbp-1 binds to integrin , igfbp-3 binding at the cell surface is decreased because the specific affinity of igfbp-3 for igf-1 is reduced when igfbp-3 interacts with cell surface molecules ( conover & powell , 1991 )
. moreover , suppression of igf - i release from igfbp-3 may occur through the interaction between igfs and igfir , thus reducing the activity of igfs .
igfbp expression during mammary gland development has also been studied by analysis of the contributions of igfbp-2 and -5 to branching mammogenesis during pregnancy ( wood & yee , 2000 ) .
all igfbps exhibit high - affinity binding with igfs ; however , igfbps also have other functions independent of igfs . igfbp-1 and -2 include the tripeptide arg - gly - asp ( rgd ) sequence , which is recognized by cell surface integrins and cell adhesion molecules .
igfbp-1 overexpression in chinese hamster cells increases cell migration ( jones et al . , 1993 ) .
additionally , igfbp-3 has independent effects on the modulation of bax and bcl-2 , inducing apoptosis in human breast cancer cells through igf - i ( butt et al . , 2000 ) and inhibiting proliferation in type i igf receptor - knockout mice ( valentinis et al . , 1995 ) .
recent studies have demonstrated that igfbp-3 regulates transforming growth factor ( tgf)- during programmed cell death through interactions between p53 and igf - independent signaling ( rajah et al . , 1997 ) .
additionally , the tgf- receptor can interact with igfbp-3 ( leal et al . , 1997 ) .
moreover , igfbp-5 has been shown to activate dna synthesis in osteoblasts through a pathway independent of igf - i ( andress , 1995 ) .
both igfbp-3 and -5 contain a putative nuclearlocalization sequence ( nls ) ( radulescu , 1994 ) and have been shown to be expressed in the nuclei using immunelogical localization methods ( jaques et al .
these results suggest that igfbps can also contribute to intracellular functions , such as proliferation , apoptosis , and cell migration .
thus , these observations also provide insights into whether the high concentrations of igfbp-5 in bovine milk interact with igf - dependent or -independent pathways . in human milk production , igfbp- 2
is more highly expressed than igfbp-1 and igfbp-3 ( erickson et al . , 1993 ; donovan & odle , 1994 ) , and igfbp-1 and igfbp-3
mrnas encoding igfbp-2 and -3 are expressed in porcine mammary glands ( simmen et al . , 1988 ) .
thus , igfbp-2 and - 3 in milk is derived from the mammary glands . in bovine serum , igfbp-2 is highly expressed during the early lactation stage and decreased during the dry period ( vicini et al . , 1991 ) .
igfbp-2 is not expressed in maternal serum , but is expressed in lactating mammary glands , suggesting that igfbp-2 is synthesized in mammary glands .
igfbp-4 expression has been identified in rat mammary glands , although the concentration is lower than that in serum ( donovan et al . , 1995 ) . igfbp-5 and -6 are not present in milk during the lactation stage .
igfs and igfbps may enter milk from the serum by paracellular interactions and secretion by epithelial cells .
however , involuting mammary glands exhibit increased levels of igfbp-2 , igfbp-4 , and igfbp-5 mrnas .
igf-1 is a survival factor for several different types of cells and is regulated by gh ( travers et al . , 1996 ) .
of all the hormonal changes that occur during the involution stage , prl is able to influence only igfbp-5 synthesis , suggesting that the prolactin is a potential inhibitor of igfbp-5 .
in bovine mammary glands , mammary gland development occurs through complex regulation of the igf pathway . although igf pathway ligands ( igf - i , igf - ii , and insulin ) affect various cellular mechanisms , including proliferation , migration , and apoptosis , the roles of these ligands in mammary gland development depend on associations with their specific receptors , e.g. , igfbps and igf - r .
2 describes the general interactions among igfbps , ligands , and their specific receptors in mammary epithelial cells .
igfs can not interact with their receptors when igf - i and igf - ii bind to igfbps owing to competitive interactions between igf and igfbps .
igfbps are degraded by proteases , whereas igfs are free to bind with igf receptors .
igfbps are present in bovine serum , whereas igfbps are expressed in mammary epithelial cells .
in addition , igfbps are secreted in bovine milk derived from mammary gland epithelial cells .
furthermore , at the involution stage , igfbps are decreased in milk and epithelial cells , along with prl and gh , resulting in degradation of mammary glands .
mammary glands are considered highly sensitive to hormones and igf signal transduction during the developmental stage .
therefore , improving our understanding of and igfbp interactions and secretion during mammary gland development may facilitate increased milk productivity through induction of mammogenesis . | the insulin - like growth factor ( igf ) pathway is a key signal transduction pathway involved in cell proliferation , migration , and apoptosis . in dairy cows , igf family proteins and binding receptors , including their intracellular binding partners , regulate mammary gland development .
igfs and igf receptor interactions in mammary glands influence the early stages of mammogenesis , i.e. , mammary ductal genesis until puberty .
the igf pathway includes three major components , igfs ( such as igf - i , igf - ii , and insulin ) , their specific receptors , and their high - affinity binding partners ( igf binding proteins [ igfbps ] ; i.e. , igfbp16 ) , including specific proteases for each igfbp .
additionally , igfs and igfbp interactions are critical for the bioactivities of various intracellular mechanisms , including cell proliferation , migration , and apoptosis .
notably , the interactions between igfs and igfbps in the igf pathway have been difficult to characterize during specific stages of bovine mammary gland development . in this review
, we aim to describe the role of the interaction between igfs and igfbps in overall mammary gland development in dairy cows . |
Tim Pawlenty says he holds no hard feelings for being passed over by Mitt Romney as his vice presidential running mate.
"I'm not disappointed. I didn't get something I didn't expect," the former Minnesota governor told ABC "This Week" host George Stephanopoulos. Pawlenty had been considered for John McCain's running mate on the 2008 Republican presidential ticket and was also widely thought of to be a top choice for Romney.
He didn't find any comfort in knowing that Obama campaign strategist David Axelrod had previously said Pawlenty would be a good vice presidential pick.
"I told David off-air, I'm reminded by the old phrase 'Get off my side, because I don't think that helped" Pawlenty joked.
Read more about: ABC News, Mitt Romney, George Stephanopoulos, Tim Pawlenty, 2012 Elections ||||| Sen. John McCain on Sunday called Mitt Romney's vice presidential pick of Rep. Paul Ryan an "excellent choice."
The Arizona Republican and unsuccessful presidential candidate in 2008 said he doesn't think the Wisconsin Republican will outshine Romney.
"I had that problem," McCain joked on "Fox News Sunday." "I don't think that's the case [with Ryan.]"
McCain again defended his selection of former Alaska Gov. Sarah Palin to join him on the ticket in 2008.
"I'm still proud of my running mate. I'm proud of Sarah and her family and the work we did," McCain said. He also noted that Ryan is also a "bold choice" who will help Romney navigate his agenda through the Congress.
Read more about: John McCain, Mitt Romney, Paul Ryan ||||| Wisconsin Gov. Scott Walker sees his home state as competitive for Republicans in the fall, despite having not awarding their electoral college votes to the GOP nominee since Ronald Reagan in 1984, and he sees his own recall election as an example of that.
"I thought it was competitive after our election, and I think it's even more competitive with Paul Ryan on the line. And I think it's not just because Paul is from Wisconsin" Walker said Sunday on NBC’s “Meet the Press."
The key to winning in Wisconsin: The truth, Walker said.
"We saw in my election two months a go what they want more than anything is people that will tell them the truth, who are courageous and willing to take on tough decisions and Mitt Romney and Paul Ryan are exactly the kind of comeback team to make that happen," Walker said.
Walker added that despite his conservative appeal, Ryan can also reach swing voters.
"He has tremendous appeal to swing voters, independent voters in states like Wisconsin, that are battleground because he's smart and he's bold but he listens and he relates well to voters all across the political spectrum," Walker said.
Read more about: Paul Ryan, Wisconsin, Scott Walker, 2012 Elections ||||| Newt Gingrich on Sunday backed Mitt Romney's vice presidential pick, Paul Ryan, saying that he no longer has issues with the Medicare provision in Ryan's budget proposal.
The former Republican House speaker and unsuccessful presidential contender, who back in May 2011 characterized Rep. Paul Ryan's budget plan as "right-wing social engineering," said on CBS's "Face the Nation" that Ryan's substance is what sets him apart.
"You now have a national leader who is capable of talking in detail with the American people about some very complicated topics," Gingrich said.
Further he said that the Wisconsin Republican congressman answered his issues with the Medicare plan by reworking it with Sen. Ron Wyden (D-Ore.) and including different options.
"He came back with an improved Medicare plan. He met my only objection," Gingrich said.
Read more about: Medicare, Newt Gingrich, Mitt Romney, Paul Ryan, Ron Wyden ||||| Obama campaign strategist David Axelrod says President Barack Obama thinks Rep. Paul Ryan is bright but "wrong'"and "extreme."
"He thinks he's a perfectly genial and bright guy. He just thinks his theory is wrong. I mean Congressman Ryan is a right-wing ideologue and that's reflected in the positions that he's taken," Axelrod told CNN “State of the Union” host Candy Crowley Sunday, before highlighting Ryan's budget plan as extreme and being against "a woman's right to choose".
"Good person. Genial person but his views are quite harsh," Axelrod said.
He also referenced Newt Gingrich in attacking Ryan's plan.
"Newt Gingrich called it right-wing social engineering, and he was right about that," Axelrod said.
Read more about: Cnn, David Axelrod, Paul Ryan, 2012 Elections ||||| Rep. Debbie Wasserman Schultz said on Sunday that by picking Rep. Paul Ryan as his running mate, Republican Presidential candidate Mitt Romney has embraced "shredding the safety net" of seniors' health care.
The Democratic National Committee chairwoman, speaking on "Fox News Sunday," said that Ryan has "embraced an extremist proposal."
The Republican ticket "would leave them to have massive gaps in coverage and drive their health care costs up," according to Wasserman Schultz.
As a member of the House Budget Committee, Wasserman Schultz said she has had a front row seat to see how the proposal by Ryan, the committee chairman, would allow insurance companies to cherry pick the best people to insure.
Read more about: Debbie Wasserman Schultz, Mitt Romney, Paul Ryan | – DC's finest wasted no time reacting to Mitt Romney's choice of Paul Ryan as his runningmate this morning, with Republicans applauding as Democrats immediately pounced on the Wisconsin Republican. Highlights from your Sunday dial, as per Politico: John McCain: Ryan is an "excellent choice," who won't outshine the top of the ticket. "I had that problem," McCain joked. Nevertheless, "I'm still proud of my runningmate. I'm proud of Sarah and her family and the work we did." David Axelrod on President Obama's opinion of Ryan: "He thinks he's a perfectly genial and bright guy. He just thinks his theory is wrong. I mean Congressman Ryan is a right-wing ideologue and that's reflected in the positions that he's taken." Tim Pawlenty: "I'm not disappointed. I didn't get something I didn't expect." Debbie Wasserman Schultz: By picking Ryan, Romney has endorsed "shredding the safety net" of Medicare and "embraced an extremist proposal." The ticket would stick seniors with "massive gaps in coverage and drive their health care costs up." Newt Gingrich on Ryan's 'right-wing social engineering': "He came back with an improved Medicare plan. He met my only objection. You now have a national leader who is capable of talking in detail with the American people about some very complicated topics." Scott Walker on Wisconsin: "I thought it was competitive after our election, and I think it's even more competitive with Paul Ryan on the line." Wisconsinites want candidates "who are courageous and willing to take on tough decisions and Mitt Romney and Paul Ryan are exactly the kind of comeback team to make that happen." |
both humans and animals can be directly infected through contact with infected tissue or urine or indirectly through contact with contaminated soil and water [ 4 , 5 ] . in humans
, typical symptoms can include fever , headaches , chills , vomiting , sore muscles , jaundice , red eyes , abdominal pain , diarrhea , and rashes .
leptospirosis can become considerably dangerous if not treated , potentially leading to kidney damage , meningitis , liver failure , and respiratory problems .
leptospirosis has been recognized as an important occupational hazard of agriculture manual laborers , sewage workers , animal handlers , forestry workers and other outdoor workers who work in wet conditions , and butchers .
the transmission cycle involves interaction between one or more animal hosts harboring leptospires , an environment favorable for its survival , and human beings .
leptospirosis in human occurs in two courses : anicteric or benign ( between 85 and 90% of cases ) and icteric or serious , also known as weil 's diseases ( between 10 and 15% of cases ) .
the wide spectrums of clinical symptoms that characterize leptospirosis make its diagnosis easily confused with other febrile diseases .
leptospira interrogans , which causes human leptospirosis , consists of over 24 serogroups made up of a large and expanding number of serovars .
these are identified by specific laboratory tests like isolation of organism by culture , specific antigen detection by gene amplification by polymerase chain reaction ( pcr ) , or antibody detection by microscopic agglutination test ( mat ) .
igm antibodies may disappear after six months and igg antibodies persist for two to 10 years after infection .
mat has a high degree of specificity , identifies serogroups , and is accepted worldwide , but it is expensive , time consuming , and labour intensive .
knowledge of high level of exposure and prevalence of leptospirosis in an area helps the primary physician in deciding to start early antibiotic treatment on clinical assessment .
antibiotic treatment should be started as soon as possible on clinical suspicion of leptospirosis because organ damage sets in by the second half of first week itself and late antibiotic treatment does not influence the outcome ( some strains like lai may cause earlier mortality in the first three days ) . presently available
culture and antibody based tests become positive only after the end of first week of infection and are unhelpful in deciding to start antibiotics early . developing vaccines for domestic animals and humans to bring down
vaccines should be specific for the group of strains particular to a region ; hence the identification of local serogroup(s ) is important .
documenting high level of seroprevalence among rodents is also important to impress upon the general public the need for rodent control and protective barriers for farmers as important methods of control of leptospirosis .
leptospirosis appears to be on the increase in kerala , tamil nadu , and andamans during the last two decades , probably due to increased farming and inadequate rodent control . since the 1980s
, outbreaks are being increasingly reported especially from the states of tamil nadu , kerala , and karnataka . till may 2001
major contribution to the number of cases had been rendered by chennai with 509 cases .
other units reporting cases are kanchipuram , cuddalore , pudukkottai , thiruvannamalai , tirupattur , kanyakumari , tiruppur , vellore , villupuram , and erode . in response to this need , the present study is an integrated approach including analysis of seroprevalence , incidence , most common clinical course , circulating serovars , and transmission factors of leptospirosis in and around vellore zone .
the town of vellore , tamil nadu , is situated on the west of the palamathi hill range .
the area is characterized by a tropical climate . according to the meteorological data acquired the meteorological observatory , the area vellore had a high mean relative humidity ( 75% ) except from march to june .
the mean monthly temperature ranges from a low of 16.9c in december to a high of 40c in may .
the study design includes the detection of different leptospiral serovars from patients reporting fever and rodents ; particularly rats are chosen for the study because they are the source of most human cases of leptospirosis .
the office of senior entomologist of zonal entomological team was contacted and proper permission to study the rate of prevalence among patients has been obtained .
the study was based on the signs and symptoms of the patients reporting fever in vellore municipal clinic ( urban malarial scheme ) .
the blood was taken from 129 patients having signs and symptoms of leptospirosis such as fever , headache , chills , rashes , body pain , vomiting , cough , abdominal pain , jaundice , and myalgia .
3 ml of intravenous blood was collected from patients and coagulated by centrifuging at 1500 rpm for 15 minutes .
details of sera sample number , patient name , age , sex , date of collection , address , duration of illness , and symptoms of the illness were also recorded . in the zet ( zonal entomological team , vellore )
laboratory the sera were examined by anti - leptospira igm dipsticks leptospira test ( macroscopic slide agglutination test ( msat ) ) which was used to detect positive cases
. then positive cases of leptospiral vials were labeled , sealed , and sent to the leptospirosis research laboratory , madhavaram , chennai , for further serovars ' examination . in the laboratory the sera were examined by microscopic agglutination test ( mat ) .
the antigen panel included the following 12 serovars : icterohaemorrhagiae , canicula , grippotyphosa , hebdomadis , pomona , autumnalis , pyrogenes , tarassovi , ballum , australis , javanica , and hardjo .
the cutoff point was dilutions 1 : 100 and the predominant serovar was that with the highest dilution .
positive cases were analyzed using epidemiological data such as age , sex , regional distribution , and serovars as well as clinical data like signs and symptoms .
about 24 rats were captured live from the market place of the vellore municipality , the mundy street .
five rats belong to the species rattus rattus ( house rat ) and another 19 rats belong to the species rattus norvegicus ( godown rat )
anti - leptospira igm dipsticks leptospira test ( macroscopic slide agglutination test ( msat ) ) was used to detect positive cases and mat ( microscopic agglutination test ) was used to determine serovars .
antigen and cut - off values were as those used for the human seroprevalence study .
serum samples were collected during the period of october 2009 , november 2009 , and february 2010 from a total of 129 febrile patients and 24 rats having signs and symptoms of leptospirosis . from the collected serum samples tested by means of macroscopic slide agglutination test ( msat ) , 10 out of 129 patients and 10 out of 24 rats were found positives ( table 1 ) . in human beings out of 10 positive cases ,
5 cases were found to be males and 5 cases were found to be females .
table 2 represents the agewise distribution of leptospiral antibodies in humans . below the age of 15 one case
was found to be positive for leptospirosis , between the ages of 16 and 25 two cases were found to be positive for leptospirosis , between the ages of 26 and 35 two cases were found to be positive for leptospirosis , between the ages of 36 and 45 two cases were found to be positive for leptospirosis , and between the ages of 46 and 55 one case was found to be positive for leptospirosis , followed by two cases above the age of 55 which were found to be positive for leptospirosis .
fever and headache were reported by 7 cases , fever , headache , and myalgia by 6 cases , fever , headache , myalgia , and body pain by 4 cases , and fever , myalgia , body pain , and vomiting by 1 case .
fever was found to have lasted for less than 5 days among one positive case and for more than 5 days and less than 10 days among 5 positive cases . among positives
one case had fever for more than 10 days and less than 15 days and for more than 20 days and less than 25 days in one positive case .
headache was reported by 107 cases , vomiting by 17 cases , and body pain by 71 cases .
cough was reported by 13 cases , myalgia by 56 cases , and abdominal pain by 10 cases .
there are 12 leptospiral serovars ( canicula , icterohaemorrhagiae , grippotyphosa , hebdomadis , pomona , autumnalis , pyrogenes , tarassovi , ballum , javanica , australis , and hardjo ) which were tested in human beings and rats . out of 10 positives human being cases , the serovar autumnalis was found to be present only in one case .
the main aim of the study was to validate the case definition . in this study
the survey conducted during the monsoon season , that is , october and november , and after the monsoon season , that is , february , shows an increase in the prevalence of leptospirosis .
these findings correlate with the findings of the study by ko et al . , which showed that leptospirosis could be the cause of many febrile illnesses in urban slums during and after the monsoon seasons .
this suggests that rain does play an important role in the dissemination of the disease to human beings .
epidemics associated with high case fatality ( greater than 15% ) break out annually during seasonal periods of heavy rainfall in poor urban areas that lack basic sanitation infrastructure .
rainfall and exposure were defined as an important correlation in diagnosing patients with leptospirosis in india . since vellore experienced scanty rainfall this monsoon ,
it would have resulted in the minimal dissemination of the disease in human beings with 8.1% during the monsoon and post monsoon season .
since rainfall plays an important part in the dissemination of disease , the basic sanitation infrastructure needs to be improved in the vellore urban zone .
the study proves the point that leptospirosis mostly occurs in working age groups and also in children .
these findings contradict with the study by davol which showed the mean age of the confirmed cases of leptospirosis was 39 years . increasing age and multiple chronic health conditions
also , children can be at risk by playing in infected water or having contact with infected animals .
after the flood occurred in mumbai in july 2000 , a total of 53 children below the age of 12 years were admitted to a pediatrics department and were tested for leptospirosis .
however , the highest mortality rates remain among the elderly and those with weil 's syndrome .
the study has also confirmed the male to female ratio was 1 : 1 .
leptospirosis is more prevalent in men and also in women ; that is , both are equally affected because of the fact that nowadays both of them were more exposed to the contaminated environment .
this finding contradicts the findings of the study by davol which showed the male to female ratio was 3 : 1 .
the commonest symptoms of those who were confirmed as having leptospirosis were fever , headache , myalgia , and vomiting ; other symptoms were not that common .
these findings correlate with the findings of the study by davol which showed all positive cases having symptoms like fever , headache , and myalgia . in this study ,
the leptospirosis was more prevalent in the cases having fever more than 5 days and less than 10 days among 5 positive cases .
fever which was found to have lasted for less than 5 days in one positive case was also reported .
these findings correlate with the findings of the study by rao et al . which showed the duration of fever of leptospirosis mostly occurs with a range of 220 days and lasts for a month also
. these findings also correlate with the findings of the study by chrispal et al .
which showed that a total of 398 acute undifferentiated febrile illnesses ( duration 521 days ) of patients were diagnosed in tertiary care hospital in south india proven scrub typhus ( 47.5% ) ; malaria ( 17.1% ) ; enteric fever ( 8.0% ) ; dengue ( 7.0% ) ; leptospirosis ( 3.0% ) ; spotted fever rickettsiosis ( 1.8% ) ; hantavirus ( 0.3% ) ; and others .
the symptoms like fever , headache , and vomiting are most noticeable during the 417 days following infection ; then the fever normally decreases and bacterial lysis occurs . totally 233 batteries of leptospira antigens ( serovars ) were present . in leptospirosis research laboratory , madhavaram , chennai , only 12 batteries of leptospira antigens ( canicula , icterohaemorrhagiae , grippotyphosa , hebdomadis , pomona , autumnalis , pyrogenes , tarassovi , ballum , javanica , australis , and hardjo ) were used to find out the serovars . out of 10 positives human being cases ,
the positive serovar case was female above 55 years and the duration of fever was 6 days .
thus remaining serovars may be present in other positive cases . in this study white fancy rats domestic albino ( rattus norvegicus ) and house rats ( rattus rattus ) were identified as the potential infection source for acute leptospirosis in humans .
no serovars were present among the positive cases because only 12 batteries of leptospira antigens were used .
some signs and symptoms are more common with particular serovars . for example , jaundice occurs in 83% of individuals with serovar icterohaemorrhagiae infection and in 30% of individuals with serovar pomona infection .
foregoing facts denote that the epidemiology of leptospirosis is complex . in a given area one
animal species harbours one serotype or , at most , a few serovars that are weakly differentiated antigenically .
it is also obvious that epidemiology of leptospirosis is dynamic and ever changing , thus responding to the ecological changes .
the public health importance of leptospirosis lies in its occupational , seasonal , sex , and age related incidence .
a further problem that can not be ignored is the fact that most people at risk of leptospirosis live in developing countries without ready access to specialized diagnostic or treatment facilities .
knowledge and research in leptospirosis are not available in most developed countries to which developing countries turn for scientific assistance .
the situation is aggravated when inadequate statistics in developed countries indicate a spuriously low rate of leptospirosis , leading to an impression that the disease is not existent or unimportant and does not justify allocation of funds for the maintenance of existing research surveillance or for new studies toward solutions to the problems .
the purpose of this experimental study is to present analytical data so as to provide information regarding the prevalence of leptospirosis in vellore zone . due to the derth of manpower and time
, this experimental study could be conducted and details are gathered from a limited number of samples only .
serological test in leptospirosis will help the clinicians to confirm the diagnosis and start the treatment at an early stage .
thus , these findings may help devise a better control strategy against the disease in this zone . | leptospirosis is a severe spirochetal zoonosis in the world .
it is considered an occupational disease of persons engaged in agriculture , sewage works , forestry , and animal slaughtering .
a study was conducted with an objective of assessing the seroprevalence of leptospirosis in and around vellore district , tamil nadu .
the study was based on the signs and symptoms of the patients reporting fever in vellore municipal clinic ( urban malarial scheme ) .
blood samples were collected from 129 patients .
animal studies were conducted from 24 rodents captured form the market place of the vellore municipality . in the zet ( zonal entomological team , vellore ) laboratory the sera were examined by macroscopic slide agglutination test ( msat ) . in the mast ,
totally 10 positive leptospiral cases from human beings and 10 positive leptospiral cases from rats ( rattus rattus and rattus norvegicus ) were found out .
then both positive cases of leptospiral vials were labeled , sealed , and sent to the leptospirosis research laboratory , madhavaram , chennai , for further serovars examination . among the various serovars identified autumnalis was more prevalent .
our findings showed that the age groups between 15 and 55 years showed more susceptibility .
particularly the adults were more infected .
the majority of seropositive individuals in the cases had only subclinical infection .
rodents were abundant and contributed to enzootic and endemic prevalence of leptospirosis . |
Anant Goel, Nabanita De, Qinglin Chen and Mark Craft. Nabanita De Facebook is facing increasing criticism over its role in the 2016 US presidential election because it allowed propaganda lies disguised as news stories to spread on the social-media site unchecked.
The spreading of false information during the election cycle was so bad that President Barack Obama called Facebook a "dust cloud of nonsense."
And Business Insider's Alyson Shontell called Facebook CEO Mark Zuckerberg's reaction to this criticism "tone-deaf." His public stance is that fake news is such a small percentage of the stuff shared on Facebook that it couldn't have had an impact. This even while Facebook has officially vowed to do better and insisted that ferreting out the real news from the lies is a difficult technical problem.
Just how hard of a problem is it for an algorithm to determine real news from lies?
Not that hard.
During a hackathon at Princeton University, four college students created one in the form of a Chrome browser extension in just 36 hours. They named their project "FiB: Stop living a lie."
The students are Nabanita De, a second-year master's student in computer science student at the University of Massachusetts at Amherst; Anant Goel, a freshman at Purdue University; Mark Craft, a sophomore at the University of Illinois at Urbana-Champaign; and Qinglin Chen, a sophomore also at the University of Illinois at Urbana-Champaign.
Their News Feed authenticity checker works like this, De tells us:
"It classifies every post, be it pictures (Twitter snapshots), adult content pictures, fake links, malware links, fake news links as verified or non-verified using artificial intelligence.
"For links, we take into account the website's reputation, also query it against malware and phishing websites database and also take the content, search it on Google/Bing, retrieve searches with high confidence and summarize that link and show to the user. For pictures like Twitter snapshots, we convert the image to text, use the usernames mentioned in the tweet, to get all tweets of the user and check if current tweet was ever posted by the user."
The browser plug-in then adds a little tag in the corner that says whether the story is verified.
For instance, it discovered that this news story promising that pot cures cancer was fake, so it noted that the story was "not verified."
FiB project
But this news story about the Simpsons being bummed that the show predicted the election results? That was real and was tagged "verified."
FiB project
The students have released their extension as an open-source project, so any developer with the know-how can install it and tweak it.
A Chrome plug-in that labels fake news obviously isn't the total solution for Facebook to police itself. Ideally, Facebook will remove fake stuff completely, not just add a tiny, easy-to-miss tag that requires a browser extension.
But the students show that algorithms can be built to determine within reasonable certainty which news is true and which isn't and that something can be done to put that information in front of readers as they consider clicking.
Facebook, by the way, was one of the companies sponsoring this hackathon event.
Word is that many Facebook employees are so upset about this situation that a group of renegade employees inside the company is taking it upon themselves to figure out how to fix this issue, BuzzFeed reports. Maybe FiB will give them a head start. ||||| The group is hoping to challenge the position by CEO Mark Zuckerberg that the platform has no responsibility to address the issue following the election of Donald Trump.
Stephen Lam / Reuters
SAN FRANCISCO — Facebook employees have formed an unofficial task force to question the role their company played in promoting fake news in the lead-up to Donald Trump's victory in the US election last week, amid a larger, national debate over the rise of fake and misleading news articles in a platform used by more than 150 million Americans. The task force, which sources tell BuzzFeed News includes employees from across the company, has already rebutted a statement made by Facebook CEO Mark Zuckerberg at a conference last week that the argument that fake news on Facebook affected the election was “a pretty crazy idea.” “It’s not a crazy idea. What’s crazy is for him to come out and dismiss it like that, when he knows, and those of us at the company know, that fake news ran wild on our platform during the entire campaign season,” said one Facebook employee, who works in the social network’s engineering division. He, like the four other Facebook employees who spoke to BuzzFeed News for this story, would only speak on condition of anonymity. All five employees said they had been warned by their superiors against speaking to press, and feared they would lose their jobs if named. The employees declined to provide many details on the task force. One employee said “more than dozens” of employees were involved, and that they had met twice in the last six days. At the moment, they are meeting in secret, to allow members of the group to speak freely and without fear of condemnation from senior management. The group plans to formalize its meetings and eventually make a list of recommendations to Facebook’s senior management. Another Facebook employee said while the task force remained small, “hundreds” of Facebook employees had expressed dissatisfaction with the company’s stance on fake news in private online chats, and wanted to support efforts to challenge that position. Facebook did not respond to a request for comment from BuzzFeed News, but in a statement to media last week, a Facebook spokesperson said, “While Facebook played a part in this election, it was just one of many ways people received their information – and was one of the many ways people connected with their leaders, engaged in the political process and shared their views.” In the wake of Trump’s victory, Facebook has been facing questions over its responsibility in spreading misinformation or failing to clamp down on the sharing of fake news. Almost half of adult Americans rely on Facebook as a source of news, a recent study by the Pew Research Center found. A recent report by BuzzFeed News found that the three large left-wing pages published false or misleading information in nearly 20% of posts, while the three big right-wing Facebook pages published it 38% of the time. The report concluded: “The best way to attract and grow an audience for political content on the world’s biggest social network is to eschew factual reporting and instead play to partisan biases using false or misleading information that simply tells people what they want to hear.” Or, as former Facebook designer Bobby Goodlatte wrote on his own Facebook wall on November 8, “Sadly, News Feed optimizes for engagement. As we’ve learned in this election, bullshit is highly engaging. A bias towards truth isn't an impossible goal. Wikipedia, for instance, still bends towards the truth despite a massive audience. But it's now clear that democracy suffers if our news environment incentivizes bullshit.”
Dado Ruvic / Reuters
Those involved in the task force who spoke to BuzzFeed News said they were reviewing whether Facebook had devoted enough resources to responding to user reports of fake news, or whether it had effectively used features that automatically scan the platform for certain kinds of offensive content. “There is a lot more we could be doing using tools already built and in use across Facebook to stop other offensive or harmful content,” said a second Facebook employee who has been a longtime engineer there. “We do a lot to stop people from posting nudity or violence, from automatically flagging certain sites to warning people who post content that doesn’t meet the community guidelines,” the employee said. He added that while Facebook users were encouraged to flag fake news, the guidelines for removing that sort of content were not clear. “If someone posts a fake news article, which claims that the Clintons are employing illegal immigrants, and that incites people to violence against illegal immigrants, isn’t that dangerous, doesn’t that also violate our community standards?” In a January 2015 update, Facebook promised fewer fake news stories by giving users a tool to self-report fake stories on their feeds. In the nearly two years since, Facebook has refused to give reporters access to metrics showing how often fake news is reported and/or removed from their platform. A BuzzFeed News report found that even when fake news was flagged on one Facebook page, it was simply moved to another. Facebook came under fire in May amid accounts by recent employees that personal bias was pushing the platform’s Trending Topics section towards more liberal news sites. In the wake of the report, Facebook fired its entire Trending Topics team, and said it would instead rely on an algorithm — though as BuzzFeed News reported, experts warned that algorithms were likely to increase the spread of fake news. The months that followed saw Facebook court controversy by removing the Pulitzer Prize-winning photo of a 9-year-old girl fleeing napalm bombs during the Vietnam war for violating nudity standards, as well as removing a breast cancer awareness video for similar reasons. As BuzzFeed News reported, the removal of the posts was repeatedly blamed on a system error, and they were eventually reinstated. “Facebook, by design, by algorithm, and by policy, has created a platform that amplifies misinformation,” said Zeynep Tufekci, an associate professor at the University of North Carolina at Chapel Hill, who has been vocal in the need for social media to consider their role in spreading fake news.
Ntb Scanpix / Reuters ||||| SAN FRANCISCO (Reuters) - Alphabet Inc’s Google (GOOGL.O) and Facebook Inc (FB.O) on Monday announced measures aimed at halting the spread of “fake news” on the internet by targeting how some purveyors of phony content make money: advertising.
The Google logo adorns the entrance of Google Germany headquarters in Hamburg, Germany July 11, 2016. REUTERS/Morris Mac Matzen
Google said it is working on a policy change to prevent websites that misrepresent content from using its AdSense advertising network, while Facebook updated its advertising policies to spell out that its ban on deceptive and misleading content applies to fake news.
The shifts comes as Google, Facebook and Twitter Inc (TWTR.N) face a backlash over the role they played in the U.S. presidential election by allowing the spread of false and often malicious information that might have swayed voters toward Republican candidate Donald Trump.
The issue has provoked a fierce debate within Facebook especially, with Chief Executive Mark Zuckerberg insisting twice in recent days that the site had no role in influencing the election.
Facebook’s steps are limited to its ad policies, and do not target fake news sites shared by users on their news feeds.
“We do not integrate or display ads in apps or sites containing content that is illegal, misleading or deceptive, which includes fake news,” Facebook said in a statement, adding that it will continue to vet publishers to ensure compliance.
Google’s move similarly does not address the issue of fake news or hoaxes appearing in Google search results. That happened in the last few days, when a search for ‘final election count’ for a time took users to a fake news story saying Trump won the popular vote. Votes are still being counted, with Democratic candidate Hillary Clinton showing a slight lead.
Nor does Google suggest that the company has moved to a mechanism for rating the accuracy of particular articles.
Rather, the change is aimed at assuring that publishers on the network are legitimate and eliminating financial incentives that appear to have driven the production of much fake news.
“Moving forward, we will restrict ad serving on pages that misrepresent, misstate, or conceal information about the publisher, the publisher’s content, or the primary purpose of the web property,” Google said in a statement.
The company did not detail how it would implement or enforce the new policy.
MACEDONIA NEWS
AdSense, which allows advertisers to place text ads on the millions of websites that are part of Google’s network, is a major source of money for many publishers.
A report in BuzzFeed News last month showed how tiny publishers in Macedonia were creating websites with fake news - much of it denigrating Clinton - which were widely shared on Facebook.
That sharing in turn led people to click on links which brought them to the Macedonian websites, which could then make money on the traffic via Google’s AdSense.
Facebook has been widely blamed for allowing the spread of online misinformation, most of it pro-Trump, but Zuckerberg has rejected the notion that Facebook influenced the outcome of the election or that fake news is a major problem on the service.
“Of all the content on Facebook, more than 99 percent of what people see is authentic,” he wrote in a blog post on Saturday. “Only a very small amount is fake news and hoaxes.”
Google has long had rules for its AdSense program, barring ads from appearing next to pornography or violent content. Work on the policy update announced on Monday began before the election, a Google spokeswoman said.
The company uses a combination of humans and artificial intelligence to review sites that apply to be a part of AdSense, and sites continue to be monitored after they are accepted, a former Google employee who worked on ad systems said. Google’s artificial intelligence systems learn from sites that have been removed from the program, speeding the removal of similar sites.
The issue of fake news is critical for Google from a business standpoint, as many advertisers do not want their brands to be touted alongside dubious content. Google must constantly hone its systems to try to stay one step ahead of unscrupulous publishers, the former employee said.
Google has not said whether it believes its search algorithms, or its separate system for ranking results in the Google News service, also need to be modified to cope with the fake news issue.
Fil Menczer, a professor of informatics and computing at Indiana University who has studied the spread of misinformation on social media, said Google’s move with AdSense was a positive step.
“One of the incentives for a good portion of fake news is money,” he said. “This could cut the income that creates the incentive to create the fake news sites.”
However, he cautioned that detecting fake news sites was not easy. “What if it is a site with some real information and some fake news? It requires specialized knowledge and having humans (do it) doesn’t scale,” he said. ||||| Facebook’s decision to clarify its ad policy language is notable because Mark Zuckerberg, the social network’s chief executive, has repeatedly fobbed off criticism that the company had an effect on how people voted. In a post on his Facebook page over the weekend, he said that 99 percent of what people see on the site is authentic, and only a tiny amount is fake news and hoaxes.
“Over all, this makes it extremely unlikely hoaxes changed the outcome of this election in one direction or the other,” Mr. Zuckerberg wrote.
Yet within Facebook, employees and executives have been increasingly questioning their responsibilities and role in influencing the electorate, The New York Times reported on Saturday.
Facebook’s ad policy update will not stem the flow of fake news stories that spread through the news feeds that people see when they visit the social network.
Facebook has long spoken of how it helped influence and stoke democratic movements in places like the Middle East, and it tells its advertisers that it can help sway its users with ads. Facebook reaches 1.8 billion people around the globe, and the company is one of the largest distributors of news online. A Pew Research Center study said that nearly half of American adults rely on Facebook as a news source.
Google’s decision on Monday relates to the Google AdSense system that independent web publishers use to display advertising on their sites, generating revenue when ads are seen or clicked on. The advertisers pay Google, and Google pays a portion of those proceeds to the publishers. More than two million publishers use Google’s advertising network.
For some time, Google has had policies in place prohibiting misleading advertisements from its system, including promotions for counterfeit goods and weight-loss scams. Google’s new policy, which it said would go into effect “imminently,” will extend its ban on misrepresentative content to the websites its advertisements run on. | – Mark Zuckerberg says fake news on Facebook didn't help tip the election in Donald Trump's favor, but that hasn't stopped the site, along with Google, from starting to address the issue. Although they're not directly taking on the fake news sites themselves, the two platforms are trying to put the kibosh on ads on sites with phony content, Reuters reports. Google is rejiggering its policy so sites with misleading content can't use its AdSense network, while Facebook is taking a similar approach with an update to its Audience Network policy, per the New York Times. "We do not integrate or display ads in apps or sites containing content that is illegal, misleading, or deceptive, which includes fake news," Facebook said in a statement. In its own remarks, Google notes it will "restrict ad serving" on pages that "misrepresent, misstate, or conceal information about the publisher" or its content. An Indiana University professor applauds the moves, noting to Reuters "this could cut the income that creates the incentive to create the fake news sites." Meanwhile, per BuzzFeed, a group of "more than dozens" of Facebook workers are rebutting their employer with an unauthorized task force looking into what role fake news on Facebook may have played in the election. "It's not a crazy idea," one Facebook worker says, referring to Zuckerberg's dismissal. "What's crazy is for him to come out and dismiss it like that, when he knows, and those of us at the company know, that fake news ran wild on our platform during the entire campaign season." The group is said to be meeting in secret to avoid reprisals from management, but it plans to soon "formalize" and submit suggestions to the company. (Business Insider highlights students who took just 36 hours to bust the fake-news flow.) |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Crags, Colorado Land Exchange Act of
2015''.
SEC. 2. PURPOSES.
The purposes of this Act are--
(1) to authorize, direct, expedite and facilitate the land
exchange set forth herein; and
(2) to promote enhanced public outdoor recreational and
natural resource conservation opportunities in the Pike
National Forest near Pikes Peak, Colorado via acquisition of
the non-Federal land and trail easement.
SEC. 3. DEFINITIONS.
In this Act:
(1) BHI.--The term ``BHI'' means Broadmoor Hotel, Inc., a
Colorado corporation.
(2) Federal land.--The term ``Federal land'' means all
right, title, and interest of the United States in and to
approximately 83 acres of land within the Pike National Forest,
El Paso County, Colorado, together with a non-exclusive
perpetual access easement to BHI to and from such land on
Forest Service Road 371, as generally depicted on the map
entitled ``Proposed Crags Land Exchange-Federal Parcel-Emerald
Valley Ranch'', dated March 2015.
(3) Non-federal land.--The term ``non-Federal land'' means
the land and trail easement to be conveyed to the Secretary by
BHI in the exchange and is--
(A) approximately 320 acres of land within the Pike
National Forest, Teller County, Colorado, as generally
depicted on the map entitled ``Proposed Crags Land
Exchange-Non-Federal Parcel-Crags Property'', dated
March 2015; and
(B) a permanent trail easement for the Barr Trail
in El Paso County, Colorado, as generally depicted on
the map entitled ``Proposed Crags Land Exchange-Barr
Trail Easement to United States'', dated March 2015,
and which shall be considered as a voluntary donation
to the United States by BHI for all purposes of law.
(4) Secretary.--The term ``Secretary'' means the Secretary
of Agriculture, unless otherwise specified.
SEC. 4. LAND EXCHANGE.
(a) In General.--If BHI offers to convey to the Secretary all
right, title, and interest of BHI in and to the non-Federal land, the
Secretary shall accept the offer and simultaneously convey to BHI the
Federal land.
(b) Land Title.--Title to the non-Federal land conveyed and donated
to the Secretary under this Act shall be acceptable to the Secretary
and shall conform to the title approval standards of the Attorney
General of the United States applicable to land acquisitions by the
Federal Government.
(c) Perpetual Access Easement to BHI.--The nonexclusive perpetual
access easement to be granted to BHI as shown on the map referred to in
section 3(2) shall allow--
(1) BHI to fully maintain, at BHI's expense, and use Forest
Service Road 371 from its junction with Forest Service Road 368
in accordance with historic use and maintenance patterns by
BHI; and
(2) full and continued public and administrative access and
use of FSR 371 in accordance with the existing Forest Service
travel management plan, or as such plan may be revised by the
Secretary.
(d) Route and Condition of Road.--BHI and the Secretary may
mutually agree to improve, relocate, reconstruct, or otherwise alter
the route and condition of all or portions of such road as the
Secretary, in close consultation with BHI, may determine advisable.
(e) Exchange Costs.--BHI shall pay for all land survey, appraisal,
and other costs to the Secretary as may be necessary to process and
consummate the exchange directed by this Act, including reimbursement
to the Secretary, if the Secretary so requests, for staff time spent in
such processing and consummation.
SEC. 5. EQUAL VALUE EXCHANGE AND APPRAISALS.
(a) Appraisals.--The values of the lands to be exchanged under this
Act shall be determined by the Secretary through appraisals performed
in accordance with--
(1) the Uniform Appraisal Standards for Federal Land
Acquisitions;
(2) the Uniform Standards of Professional Appraisal
Practice;
(3) appraisal instructions issued by the Secretary; and
(4) shall be performed by an appraiser mutually agreed to
by the Secretary and BHI.
(b) Equal Value Exchange.--The values of the Federal and non-
Federal land parcels exchanged shall be equal, or if they are not
equal, shall be equalized as follows:
(1) Surplus of federal land value.--If the final appraised
value of the Federal land exceeds the final appraised value of
the non-Federal land parcel identified in section 3(3)(A), BHI
shall make a cash equalization payment to the United States as
necessary to achieve equal value, including, if necessary, an
amount in excess of that authorized pursuant to section 206(b)
of the Federal Land Policy and Management Act of l976 (43
U.S.C. 1716(b)).
(2) Use of funds.--Any cash equalization moneys received by
the Secretary under paragraph (1) shall be--
(A) deposited in the fund established under Public
Law 90-171 (commonly known as the ``Sisk Act''; 16
U.S.C. 484a); and
(B) made available to the Secretary for the
acquisition of land or interests in land in Region 2 of
the Forest Service.
(3) Surplus of non-federal land value.--If the final
appraised value of the non-Federal land parcel identified in
section 3(3)(A) exceeds the final appraised value of the
Federal land, the United States shall not make a cash
equalization payment to BHI, and surplus value of the non-
Federal land shall be considered a donation by BHI to the
United States for all purposes of law.
(c) Appraisal Exclusions.--
(1) Special use permit.--The appraised value of the Federal
land parcel shall not reflect any increase or diminution in
value due to the special use permit existing on the date of the
enactment of this Act to BHI on the parcel and improvements
thereunder.
(2) Barr trail easement.--The Barr Trail easement donation
identified in section 3(3)(B) shall not be appraised for
purposes of this Act.
SEC. 6. MISCELLANEOUS PROVISIONS.
(a) Withdrawal Provisions.--
(1) Withdrawal.--Lands acquired by the Secretary under this
Act shall, without further action by the Secretary, be
permanently withdrawn from all forms of appropriation and
disposal under the public land laws (including the mining and
mineral leasing laws) and the Geothermal Steam Act of 1930 (30
U.S.C. 1001 et seq.).
(2) Withdrawal revocation.--Any public land order that
withdraws the Federal land from appropriation or disposal under
a public land law shall be revoked to the extent necessary to
permit disposal of the Federal land parcel to BHI.
(3) Withdrawal of federal land.--All Federal land
authorized to be exchanged under this Act, if not already
withdrawn or segregated from appropriation or disposal under
the public lands laws upon enactment of this Act, is hereby so
withdrawn, subject to valid existing rights, until the date of
conveyance of the Federal land to BHI.
(b) Postexchange Land Management.--Land acquired by the Secretary
under this Act shall become part of the Pike-San Isabel National Forest
and be managed in accordance with the laws, rules, and regulations
applicable to the National Forest System.
(c) Exchange Timetable.--It is the intent of Congress that the land
exchange directed by this Act be consummated no later than one year
after the date of the enactment of this Act.
(d) Maps, Estimates, and Descriptions.--
(1) Minor errors.--The Secretary and BHI may by mutual
agreement make minor boundary adjustments to the Federal and
non-Federal lands involved in the exchange, and may correct any
minor errors in any map, acreage estimate, or description of
any land to be exchanged.
(2) Conflict.--If there is a conflict between a map, an
acreage estimate, or a description of land under this Act, the
map shall control unless the Secretary and BHI mutually agree
otherwise.
(3) Availability.--Upon enactment of this Act, the
Secretary shall file and make available for public inspection
in the headquarters of the Pike-San Isabel National Forest a
copy of all maps referred to in this Act. | . Crags, Colorado Land Exchange Act of 2015 (Sec. 4) This bill directs the Department of Agriculture (USDA), if the Broadmoor Hotel, Inc., (BHI) offers to convey to the USDA 320 acres of specified nonfederal land in the Pike National Forest in Teller County, Colorado, and a permanent trail easement for the Barr Trail in El Paso County, Colorado, to accept the offer and convey to BHI 83 acres of specified federal land within the Forest, together with a non-exclusive perpetual access easement for BHI to and from such land on Forest Service Road 371. The nonexclusive perpetual access easement granted to BHI shall allow: (1) BHI to fully maintain, at its own expense, and use Forest Service Road 371 from its junction with Forest Service Road 368 in accordance with historic BHI use and maintenance patterns; and (2) full and continued public and administrative access and use of FSR 371 in accordance with the existing Forest Service travel management plan, or as it may be revised by USDA. (Sec. 5) The USDA shall determine the values of the lands to be exchanged through appraisals following specified requirements. The values shall be equal, or if they are not equal, equalized as prescribed by this Act. The appraised value of the federal land parcel shall not reflect any increase or diminution in value due to the existing special use permit to BHI on the parcel and its improvements. The Barr Trail easement donation shall not be appraised for purposes of this Act. (Sec. 6) The lands acquired by the USDA under this Act shall, without further USDA action, be permanently withdrawn from all forms of appropriation and disposal under the public land laws (including the mining and mineral leasing laws) and the Geothermal Steam Act of 1930, except to the extent necessary to permit the disposal of the federal land parcel to BHI. The land acquired by the USDA under this Act shall become part of the Pike-San Isabel National Forest. It is the intent of Congress that the land exchange directed by this Act be completed within one year of this Act's enactment. |
Paramount Pictures / Skydance Productions
Those madcap galoots, Captain James T. Kirk (Chris Pine) and “Bones” McCoy (Karl Urban), are trying to escape a band of chalk-faced aboriginals on the Class-M planet Nibiru. Having broken a Starfleet rule by intervening in a prehistoric civilization, they run for their lives, like Bob Hope and Bing Crosby hightailing it out of Zanzibar after one of their schemes went kaflooey. Reaching a cliff, with the natives in angry pursuit, Jim and Bones leap desperately toward the water far below. Now they’re Butch and Sundance, in every way except for yelling, “S—!” as they plummet to safety. They’re just one Enterprise crew member short of being the Three Stooges.
Actually, Moe — Mr. Spock (Zachary Quinto) — is trapped nearby in an erupting volcano, its spewing lava reminiscent of the kitsch special effects from the 1940 One Million B.C., but in 3-D and gaudy color. Kirk, back on the Enterprise, ignores another Starfleet dictum and flies into the inferno to rescue Spock; the primitive Nibirians gape at the spacecraft with the same perplexed wonder as the apes at the 2001 monolith. When the Enterprise returns to Earth, Rear Admiral Christopher Pike (Bruce Greenwood) demotes Kirk to Starfleet Academy and separates him from Spock. Pike might be an exasperated homeroom teacher forced to keep two troublemakers apart — or a father regretting that he gave his reckless teen son the keys to the starship.
(READ: Can the new Star Trek Make Science Fiction Fun Again?)
Any prequel series to a movie franchise is obliged to imagine younger versions of famous characters. We know from the Star Trek TV series, spawned in 1966 by Gene Roddenberry, and from the six subsequent feature films starring William Shatner and Leonard Nimoy, that Kirk is the man of action, Spock the half-Vulcan half-man of thought. J.J. Abrams applied that dichotomy to his 2009 Star Trek reboot and now to the first sequel to the prequel, Star Trek Into Darkness. (Abrams has his plate full with revered sci-fi franchises. Disney has entrusted him with reviving Star Wars.)
(READ: Mary Pols’ review of J.J. Abrams’ 2009 Star Trek)
The difference between the Roddenberry and Abrams Kirks: This one has a severe case of arrested development. He’s always spoiling for a fight that might endanger his crew, nay, alter the fate of the universe. Not that Into Darkness doesn’t provide bustling fun equal to its modest ambitions or that the script (by the writing duo of Robert Orci and Alex Kurtzman and Abrams’ co-creator of Lost, Damon Lindelof) doesn’t find rich plunder in the maleficence of an early Star Trek villain. But with its emphasis on its hero’s adolescent anger, the movie turns this venerable science-fiction series — one that prided itself on addressing complex issues in a nuanced and mature fashion — into its own kids’ version: Star Trek Tiny Toons. At times, the viewer is almost prodded to mutter, “Grow up!”
When catastrophe reunites the crew members for one more mission, we find the rest of them suffering growing pains as well. Spock, who’s hardly on speaking terms with Kirk after the Nibiru caper, endures a puppy-love spat with Communications Officer Uhura (Zoe Saldana). Engineer Scotty (Simon Pegg) has a tiff with Kirk and decides to sit this voyage out, though he’ll prove useful later. That leaves Ensign Chekov (Anton Yelchin) to keep the Enterprise from exploding midflight — another case of a boy trying to do a man’s job. Ship’s helmsman Sulu (John Cho) is not prominent enough to have a teething problem; he and Bones prowl the craft and work to keep their less stable colleagues out of trouble.
(READ: J.J. Abrams on making Super 8)
The Enterprise also has a stowaway, Carol Marcus (Alice Eve). Security must be lax under Kirk’s command, especially as regarding a pretty blonde. Carol adds the requisite erotic tension — actually sub-erotic, since sexual interest is irrelevant in a boys-in-space epic. There was more sincere budding love in Abrams’ last film, the excellent Super 8, in which four 12-year-old boys teamed with a 14-year-old girl to do battle against an alien invasion and its government cover-up. Those middle schoolers faced their challenges far more sensibly than some of the Enterprise crew members do theirs. They’re like the kids from Glee charged with saving the universe — or getting a third season for Smash. (All right, some missions are impossible.)
** Warning! Spoilers ahead **
A few grownups step into this Darkness. Pike is the mutton-chopped father figure who, in the 2009 Star Trek, saved Kirk from a bar fight with space cadets and recommended him for the academy. Admiral Marcus (Peter Weller, more than a quarter-century after he starred in RoboCop) is Pike’s superior and Carol’s dad; his galactic trigger finger proves even itchier than Kirk’s. But the real adult supervision comes from a fellow named John Harrison (Benedict Cumberbatch). Harrison mounts a one-man 9/11-style terrorist assault on Starfleet Central, destroys the archive housing Klingon intel and, in the process, wipes out so many of the senior officers that Kirk and the gang, among the few survivors, are assigned to capture him on Kronos, the Klingon home planet.
(READ: Corliss on the first season of the original Star Trek)
Good luck with that. “He is ruthless, brilliant and will not hesitate to kill every single one of you,” warns Spock Prime (Nimoy, back for another fleeting guest shot). Harrison is also the movie’s one compelling character, and if you want to know his true identity, don’t read the cast list on the Internet Movie Database. We shall say only that he has his origins in the “Space Seed” episode of the TV show’s first season; he later graced one of the best of the feature films. (For teasing purposes, we’ll add that that picture’s title anagrams to What the ho, Frank! and the actor’s name to Drat! Abnormal Icon!) Cumberbatch raises the anxiety level and performance standard whenever he’s onscreen. As the latest Sherlock Holmes on BBC, he has embodied a supersmart hero of the 1890s. Here he is the supersmart villain of the 1990s, teleported to the 23rd century.
** All Clear! You have left the Spoiler Zone **
With high cheekbones and the penetrating stare of a superior automaton — or maybe just a posh Englishman looking pityingly on the other, mostly American actors — Cumberbatch infuses Into Darkness with a creepy class. Everyone else has to make do by looking fabulous. Chris Pine’s face has the blurry handsomeness of James Dean painted on velvet. (When he and Greenwood confront each other, going eyeball to eyeball, the only question is: Whose are bluer?) Saldana, remembered as the Pandoran princess in Avatar, wears eyelashes as long as light-years; and on Kronos, when she speaks Klingon, it sounds like a Sonnet from the Portuguese. Eve, the perfect woman in She’s Out of My League, provides light-dark contrast to Saldana and flashes her panties, perhaps to establish her availability as a Kirk girlfriend in a later episode.
Can a woman ever lasso this wild man? His heroic impulsiveness occasionally translates as the crackpottery of a gung-ho sergeant leading his men into the Big Galactic Muddy. When Pike disciplines Kirk and reminds him that he is meant to be primarily an explorer, not a warrior, it might be the spirit of Gene Roddenberry speaking. The original series didn’t hold to the suspicious, maybe paranoid belief that each new planet (read: the Soviet Union) harbored a doomsday threat to Starfleet (read: America). The show sought accommodation and understanding with distant peoples as much as triumph over alien warlords. That’s why Kirk and Spock had equal dramatic and ethical pull.
(READ: a 1975 story on the earliest Trekkies by subscribing to TIME)
Parables of equanimity suit a TV series more than an action picture; one is essentially liberal, the other conservative. And the ’60s, they were so long ago. Abrams knows that every contemporary sci-fi film is really a war movie and that Star Trek, to be modern, had to grow a tougher skin. Kirk, the rogue warrior, may be heading for the borderline of sociopathy, but he has to be right in his hunches about the predatory nature of the creatures out there. Yet that makes Spock an irrelevancy — the professor type from old sci-fi movies who tried reasoning with the evil or barbarous life forms before they swatted him into unconsciousness. A pacifist who hopes to be Magellan, Spock must stand aside while the cowboy king does his thing.
One aspect of Star Trek, at least, has to be honored in any prequel. Our planet and the universe can be on the brink of annihilation, but most of the Enterprise crew members are immortal; they must survive to populate the 1966 TV show. Into Darkness flirts with the demise of one prominent character, but when he revives, Bones says, “Oh, don’t be melodramatic. You were barely dead.” This series will survive as well, until 2016 — when, you can bet, there will be a third Star Trek to celebrate the TV show’s 50th anniversary. Here’s hoping that those three years will bestow a measure of maturity on all concerned: Kirk and his bright curators too. ||||| "Star Trek Into Darkness": Who made J.J. Abrams the sci-fi god? These are the voyages of the -- oh, the hell with it! Let's blow some stuff up and chase a generic supervillain
Apparently I missed the papal conclave. Not the one with Pope Francis and the Argentine torture scandals; I heard about that. I’m talking about the high-level secret meeting in the super-secret sub-orbital space fortress where J.J. Abrams was elected sole curator, conservator and monarch of three generations’ worth of nerdy pop culture history. Seriously, people, how does one guy end up in charge of both the “Star Trek” and “Star Wars” reboots? Give me a break! Isn’t that kind of nuts and megalomaniacal and wrong and just too much of the same flavor of peppermint hazelnut chip ice cream from that one summer in Connecticut, when “Alligator Woman” was on the radio every single day? (We can discuss this another time, but if I could create a world in which Joss Whedon had taken on “Star Trek,” and given Abrams the freakin’ “Avengers,” I’d do it in a heartbeat.)
I’ve got nothing against J.J. Abrams. He’s got verve and enthusiasm and considerable technical ability, and amid the hackwork that underlies so much of big-budget film and TV that stands out. I have generally enjoyed his work over the years, although if you pressed me I’d probably express the snobby opinion that it’s all been very slightly downhill since “Felicity” and “Alibi.” I thought about becoming a big fan of “Lost” and sort of meant to, but then I noticed that I wasn’t getting any younger and there were lots of other things to pay attention to, and also that the show had patches of remarkable dumbness. “Super 8” was super fun, two summers back, but also conveyed the odd sensation that Abrams lacked any artistic personality of his own, so he had flayed Steven Spielberg and was wearing his skin, like an Aztec sacrificial priest.
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But if you’re a fan of either “Star Trek” or “Star Wars” or both, you don’t need me to deal you that they’re very different universes with divergent and often warring realms of fandom. (You “both” people: What the hell is wrong with you? Are you Episcopalians? Do you use both Android and iOS, depending on day of the week? Do you root for both the Yankees and the Red Sox, because both cities are kinda cool?) Abrams’ infamous comments that he was never much of a “Star Trek” fan – “It always felt too philosophical to me,” he recently told Jon Stewart – made it seem as if he’s been using the second-most-popular science-fiction franchise of all time as a placeholder, while waiting for the gig he really wanted, the one without all that boring philosophy, to open up. Next up, Abrams plans remakes of “Jaws” and “The Godfather” and “Midnight Cowboy” and “The Exorcist,” all made slightly too jovial and with gratuitous lens-flare. (OK, that’s not true, at least not yet.)
So that’s an admittedly long-winded way of working my way around to the question of what’s wrong (and right) with “Star Trek Into Darkness,” Abrams’ splashy and largely agreeable mega-budget sequel to his 2009 “Star Trek” reboot. As “Trek” buffs already understand – and have furiously debated for the last four years – this reboot features Mr. Spock (Zachary Quinto, who is terrific) and Capt. Kirk (Chris Pine, who is, um, not terrific) but is set not in the universe of Gene Roddenberry’s original TV show and subsequent films but in an alternate timeline often dubbed the “Abramsverse” (though in fact it’s mostly the work of screenwriter Roberto Orci). This alternate universe features many of the same characters and a roughly similar reality but all kinds of stuff is different and wildly inconsistent, from the size of the starships (many times larger) to the existence of many previously unknown alien races to the fact that Jim Kirk can drive a stick-shift. (You think I’m kidding!) If you’re really interested, go study the intensely detailed work of Bernd Schneider at Ex Astris Scientia, but I can summarize: The Abramsverse is considered canonical by hardcore fans only because they have no choice; it's “Trek”-flavored, but largely made-up and WTF.
To extend the metaphor still further, the Abrams “Star Trek” movies feel as if they didn’t just depict an alternate universe but were created in one – a universe in which the original “Star Trek” was an action-adventure Marvel Comics title rather than a geeky, Enlightenment-saturated 1960s TV series. Start with that idea, and you can make sense of almost everything about “Star Trek Into Darkness.” There are the pumped-up, gym-toned physiques of Kirk, Spock, Lt. Uhura (Zoe Saldana) and everybody else, and the cutting-edge synthetic fabrics that make the whole thing resemble a 23rd-century workout video. There are the often spectacular and just as often nonsensical CGI outer-space action sequences (I saw this in IMAX 3-D, and it looked terrific). There’s the dumbed-down dialogue – not Spock’s, in fairness -- and the incoherent scheming of Benedict Cumberbatch’s super-soldier ultra-villain, a compelling presence who turns out, depressingly, to be kind of an idiot.
Yes, it’s true that Abrams and writers Orci, Alex Kurtzman and Damon Lindelof have reinvented one of the most feared and revered villains from the original “Trek” universe, and have also worked a neat inversion on a key plot twist from the most beloved of the “Trek” movies. (Let’s leave it there for now, shall we?) There are references and in-jokes aplenty for “Star Trek” fans, but let’s be honest: That’s probably 10 percent of the target audience, and “Star Trek Into Darkness” never even tries to feel like an “old-continuity” “Trek” fiction. This is a brawny, mass-audience, popcorn-transmission vehicle, pretty much in the vein of Whedon’s “Avengers” and Shane Black’s “Iron Man 3,” and possibly not quite as successful as either. It’s made with verve and gusto – some of the outer-space shots are among the most beautiful to be found in the genre -- and an entirely predictable formula. It throws in a few winks at the “Star Trek” nerds in the same obligatory way it slaps a veneer of post-9/11 apocalyptic sobriety on its plot. (I’m getting pretty sick of that one, honestly.)
After an eye-popping but ultimately irrelevant prelude in which Kirk violates the Prime Directive in order to save Spock from the crater of an erupting volcano, and suffers a temporary career setback, Starfleet offices in London and San Francisco – which evidently have crappy security or none at all -- come under attack from the renegade secret agent played by Cumberbatch. After a lot of action-movie roaring and smirking and blam-blam-blam, Kirk gets his captain’s chair back, and heals his rift with his overly honest Vulcan senior officer, but only because Starfleet’s commander, Adm. Marcus (the leathery Peter Weller) is sending them to the Klingon homeworld armed with a bunch of super-secret photon torpedoes – all to kill one guy at the risk of starting a catastrophic war. Cough-cough-Osama-cough.
There’s a lot of good material in the excitingly paced first half, especially the “Starship Troopers”-style suggestion that the Federation is being perverted into an expansionist military empire while its citizens aren’t paying attention. Hmm, where'd they come up with that crazy idea? Production design never fails to look great, but the plot switchbacks become increasingly obvious as the movie plods on, and despite Cumberbatch’s abundant charisma the writers deliberately avoid twisting the character’s samey, invincible, permanently pissed-off supervillain-ness in any interesting directions. One of the biggest differences “Trek” buffs have noted between the Abramsverse and the “Prime Universe” is the disappearance of moral cost and consequence (as in the destruction of Vulcan in the 2009 film). Here we see an enormous terrorist attack, many times bigger than 9/11, which comes and goes as a plot element and is mentioned again.
There’s absolutely nothing wrong with “Star Trek Into Darkness” – once you understand it as a generic comic-book-style summer flick faintly inspired by some half-forgotten boomer culture thing. (Here’s something to appreciate about Abrams: This is a classic PG-13 picture, with little or no sex or swearing, but one that never condescends.) That’s the way almost everyone will experience it, and fair enough. Still, if you feel like bitching about it, come on over. We’ll crack a couple of watery brews and complain (in Klingon) about Uhura’s ill-fitting romance with Spock, or Chris Pine’s frat-boy weightlifter Kirk, who completely lacks the air of provincial, semi-educated suavity that made William Shatner the greatest bad actor in TV history. Or the fact that those in charge of the “Star Trek” universe could have entrusted its rebirth to someone who actually liked it. ||||| Star Trek Into Darkness opens on a primitive planet, where the natives are restless and a volcano, in mid-eruption, traps First Officer Spock (Zachary Quinto) over a boiling ocean of lava. Naturally, the Vulcan stays cool as a cucumber, ready to die to save his crew an impeccably logical decision that also happens to be the compassionate one. But Capt. James T. Kirk (Chris Pine), commander of the U.S.S. Enterprise, has other ideas. He'll rescue Spock, even if that means violating a Federation rule that says the Enterprise can't be exposed to the planet's uncivilized hordes. Kirk, who never met a regulation he couldn't trash, guides the starship up into the air and over to where his comrade is about to perish, and the white-mud-caked warriors stare at the ship as if it were a god. It's a sensation that the movie transmits to the audience, since the Enterprise, emitting an awesome thrummm, never looked quite so massive or looming.
Four years ago, director J.J. Abrams rebooted the Star Trek franchise with great swagger by treating the launch film as a unique pop culture origin story. The movie was all about how the Enterprise crew first came together, but really it was about how Chris Pine and Zachary Quinto rose up to become those superheroes of yore, Kirk and Spock, by echoing the looks, voices, and personalities of William Shatner and Leonard Nimoy just enough, while still making the roles their own. The two actors now really have a chance to get their Kirk and Spock on. Pine, with ice blue eyes and lips that dance on the edge of a smirk, does something marvelously clever: He evokes Shatner's hamminess by underplaying it. And Quinto makes the glowering, dagger-browed Spock almost fiercely withholding. Into Darkness provides room for these actors to deepen their interplay. The movie has an often sinister grandeur, but the images never overpower the human (or Vulcan) factor.
Like Abrams' first Trek movie, this one is positioned as a prequel to the original TV series and subsequent films, though it also lifts (and twists) elements from that sacred text, 1982's Star Trek II: The Wrath of Khan. Kirk and Spock, each following his own nature (hothead, detached brainiac), are usually at loggerheads, but even when they wind up coming to the same conclusion, they can't stop arguing about how they got there, and that's part of the movie's texture of cocky one-upmanship. The whole Enterprise crew has become a collection of colliding egos. Zoë Saldana's badass Uhura, who's in the middle of a lovers' quarrel with Spock; John Cho as the so-stoic-he's-cool Sulu; Simon Pegg's frantically funny and resourceful Scotty these characters pop out at us with a new dynamism. And they all confront a villain who has been brilliantly retrofitted to throw everyone, including the audience, off guard.
This dastardly dude is a boyish-looking terrorist named John Harrison, who starts off by striking a note of urban chaos. But it's not long before he's revealed to be how can I say this? a foe familiar to Trekkies, with a concealed agenda and 70 of his comrades cryogenically frozen in photon-torpedo capsules. He's played by rising British star Benedict Cumberbatch in a totally original way, with the physicality of a dancer and an eager, puckish sincerity that ingeniously disguises his vengeful mission. Once Harrison's been captured and placed in a cell, Kirk has to listen to his own hunches about who this man is and what he wants. That's the real ''darkness'' the film's title is referring to: the place where you're no longer certain what the right thing to do is. And that's a place of genuine excitement. Into Darkness is a sleek, thrilling epic that's also a triumphantly witty popcorn morality play. It's everything you could want in a Star Trek movie. A | – Four years after he first thrilled audiences and annoyed hard core Trekkies with Star Trek, JJ Abrams is back with Star Trek Into Darkness, and critics are gushing over it, saying it's even more thrilling—and perhaps even more likely to annoy fans. "It's crazy good," gushes Peter Travers at Rolling Stone. "Kudos to Abrams for going bigger without going stupid." The plot, like the best Trek stories, is topical, centered on domestic terrorism, and Benedict Cumberbatch's John Harrison is "a villain for the ages." The "darkness" in the title refers to the moral gray area Kirk and company are forced into, and "that's a place of genuine excitement," writes Owen Gleiberman at Entertainment Weekly. This is a smart blockbuster, "a triumphantly witty popcorn morality play. It's everything you could want in a Star Trek movie." Richard Corliss at Time found himself a bit annoyed at the perpetual immaturity shown by Abrams' version of Kirk. "The movie turns this venerable science-fiction series—one that prided itself on addressing complex issues in a nuanced and mature fashion—into its own kids’ version: Star Trek Tiny Toons," he writes. And Andrew O'Hehir at Salon is all too willing to speak for the disgruntled fan. The movie's fine, he writes, "once you understand it as a generic comic-book-style summer flick faintly inspired by some half-forgotten boomer culture thing." But he for one is annoyed by its "entirely predictable formula," its "dumbed-down dialogue," and its abandonment of Roddenberry's moral heft. "Those in charge of the Star Trek universe could have entrusted its rebirth to someone who actually liked it." |
the ground state of exotic fermion cooper pairing with mismatched fermi surfaces is a longstanding problem in the theory of superconductivity @xcite . in electronic superconductors ,
the mismatched fermi surfaces are normally induced by the zeeman energy splitting @xmath0 in a magnetic field . for
@xmath1-wave pairing at weak coupling , it is known that , at a critical field @xmath2 where @xmath3 is the pairing gap at vanishing mismatch , a first - order phase transition from the gapped bcs state to the normal state occurs @xcite .
further theoretical studies showed that the inhomogeneous larkin - ovchinnikov - fulde - ferrell ( loff ) state can survive in a narrow window @xmath4 , where the upper critical field @xmath5 @xcite .
however , since the thermodynamic critical field is much lower than @xmath6 due to strong orbit effect , it is rather hard to observe the loff state in ordinary superconductors @xcite .
in recent years , experimental evidences for the loff state in some superconducting materials have been reported @xcite . on the other hand ,
exotic pairing phases have promoted new interest in the studies of dense quark matter under the circumstances of compact stars @xcite and ultracold atomic fermi gases with population imbalance @xcite .
color superconductivity in dense quark matter appears due to the attractive interactions in certain diquark channels @xcite . because of the constraints from beta equilibrium and electric charge neutrality , different quark flavors ( @xmath7 , @xmath8 , and @xmath1 ) acquire mismatched fermi surfaces .
quark color superconductors under compact - star constraints as well as atomic fermi gases with population imbalance therefore provide rather clean systems to realize the long - sought exotic loff phase . around the tricritical point in the temperature - mismatch phase diagram
, the loff phase can be studied rigorously by using the ginzburg - laudau ( gl ) analysis since both the gap parameter and the pair momentum are vanishingly small @xcite .
it was found that the solution with two antipodal wave vectors is the preferred one @xcite .
however , the real ground state of the loff phase is still debated due to the limited theoretical approaches at zero temperature .
so far rigorous studies of the loff phase at zero temperature are restricted to its 1d structures including the fulde - ferrell ( ff ) state with a plane - wave form @xmath9 and the larkin - ovhinnikov ( lo ) state with an antipodal - wave form @xmath10 .
a recent self - consistent treatment of the 1d modulation @xcite show that a solitonic lattice is formed near the lower critical field , and the phase transition to the bcs state is continuous . near the upper critical field
the gap function becomes sinusoidal , and the transition to the normal state is of first order .
in addition to these 1d structures , there exist a large number of 3d crystal structures .
the general form of a crystal structure of the order parameter can be expressed as @xmath11 a specific crystal structure corresponds to a multi - wave configuration determined by the @xmath12 unit vectors @xmath13 ( @xmath14 ) . in general , we expect two competing mechanisms : increasing the number of waves tends to lower the energy , but it may also causes higher repulsive interaction energy between different wave directions . in a pioneer work ,
bowers and rajagopal investigated 23 different crystal structures by using the gl approach @xcite , where the grand potential measured with respect to the normal state was expanded up to the order @xmath15 , @xmath16 with @xmath17 being the density of state at the fermi surface and the pair momentum fixed at the optimal value @xmath18 . among the structures with @xmath19 , the favored one seems to be the body - centered cubic ( bcc ) with @xmath20 @xcite .
further , it was conjectured that the face - centered cubic ( fcc ) with @xmath21 @xcite is the preferred structure since its @xmath22 is negative and the largest @xcite . for bcc structure ,
the gl analysis up to the order @xmath15 predicts a strong first - order phase transition at @xmath23 with the gap parameter @xmath24 @xcite .
the prediction of a strong first - order phase transition may invalidate the gl approach itself . on the other hand , by using the quasiclassical equation approach with a fourier expansion for the order parameter , combescot and mora @xcite predicted that the bcc - normal transition is of rather weak first order : the upper critical field @xmath25 is only about @xmath26 higher than @xmath27 with @xmath28 at @xmath29 .
if this result is reliable , it indicates that the higher - order expansions in the gl analysis is important for quantitative predictions .
to understand this intuitively , let us simply add the eighth - order term @xmath30 to the gl potential ( [ gl ] ) .
a detailed analysis of the influence of a positive @xmath31 on the phase transition is presented in appendix a. we find that with increasing @xmath31 , the first - order phase transition becomes weaker and the upper critical field @xmath25 decreases .
for @xmath32 , the phase transition approaches second order and @xmath33 .
therefore , to give more precise predictions we need to study the higher - order expansions and the convergence property of the gl series , or use a different way to evaluate the grand potential without assuming a small value of @xmath34 . for a specific crystal structure given by ( [ crystal ] ) , it is periodic in coordinate space . as a result ,
the eigenvalue equation for the fermionic excitation spectrum in this periodic pair potential , which is known as the bogoliubov - de gennes ( bdg ) equation , is in analogy to the schrdinger equation of quantum particles in a periodic potential .
this indicates that the fermionic excitation spectrum has a band structure , which can be solved from the bdg equation .
the grand potential can be directly evaluated once the fermionic excitation spectrum is known @xcite . in this work , we present a solid - state - like calculation of the grand potential of the bcc structure .
our numerical results show that the phase transition from the bcc state to the normal state is of rather weak first order , consistent with the work by combescot and mora @xcite .
this implies that it is quite necessary to evaluate the higher - order terms in the gl expansion to improve the quantitative predictions .
to be specific , we consider a general effective lagrangian for two - flavor quark pairing at high density and at weak coupling .
the lagrangian density is given by @xcite @xmath35\psi+{\cal l}_{\rm int},\ ] ] where @xmath36 denotes the two - flavor quark field and @xmath37 is the quark dispersion with the momentum operator @xmath38 . in the momentum representation
we have @xmath39 .
the quark chemical potentials are specified by the diagonal matrix @xmath40 in the flavor space , where @xmath41 the interaction lagrangian density which leads to cooper pairing between different flavors can be expressed as @xcite @xmath42 where @xmath43 is the coupling constant and @xmath44 is the second pauli matrix in the flavor space .
notice that we have neglected the antiquark degree of freedom because it plays no role at high density and at weak coupling .
we have also neglected the color and spin degrees of freedom , which simply give rise to a degenerate factor .
color superconductivity is characterized by nonzero expectation value of the diquark field @xmath45 . for the purpose of studying inhomogeneous phases
, we set the expectation value of @xmath46 to be static but inhomogeneous , i.e. , @xmath47 . with the nambu - gorkov spinor @xmath48
, the mean - field lagrangian reads @xmath49 the order parameters of the bcc and fcc structures can be expressed as @xmath50\end{aligned}\ ] ] and @xmath51 respectively .
therefore , we consider a 3d periodic structure where the unit cell is spanned by three linearly independent vectors @xmath52 , @xmath53 , and @xmath54 with @xmath55 for bcc and @xmath56 for fcc .
the order parameter is periodic in space , i.e. , @xmath57 .
it can be decomposed into a discrete set of fourier components , @xmath58}e^{i{\bf g}_{[lmn]}\cdot { \bf r}},\end{aligned}\ ] ] where the reciprocal lattice vector @xmath59 reads @xmath60}=\frac{2\pi}{a}\left(l{\bf e}_x+m{\bf e}_y+n{\bf e}_z\right),\ \ \ l , m , n\in \mathbb{z}.\end{aligned}\ ] ] the fourier component @xmath61}$ ] can be evaluated as @xmath62\end{aligned}\ ] ] and @xmath63 for bcc and fcc structures , respectively .
then we consider a finite system in a cubic box defined as @xmath64 $ ] with the length @xmath65 . for convenience
we impose the periodic boundary condition .
the thermodynamic limit is reached by setting @xmath66 . using the momentum representation
, we have the fourier transformation @xmath67 here @xmath68 is the volume of the system , @xmath69 is the fermion matsubara frequency , and the quantized momentum @xmath70 is given by @xmath71 with @xmath72 .
the partition function of the system is given by @xmath73[d\psi^\dagger]e^{-{\cal s}}\ ] ] with the euclidean action @xmath74 .
the grand potential per volume reads @xmath75 in the mean - field approximation , the action @xmath76 is quadratic .
therefore , the partition function @xmath77 and grand potential @xmath78 can be evaluated . using the fourier expansions for @xmath79 and @xmath34
, we obtain the mean - field action @xmath80 where the effective hamiltonian matrix @xmath81 reads @xmath82 the effective hamiltonian @xmath81 is a huge matrix in nambu - gorkov , flavor , and ( discrete ) momentum spaces .
it is hermitian and can in principle be diagonalized . assuming that the eigenvalues of @xmath81 is denoted by @xmath83
, we can formally express the grand potential as @xmath84 where the function @xmath85 .
the summation over @xmath59 can be worked out as @xmath86 . in practice ,
diagonalization of the matrix @xmath81 is infeasible .
however , @xmath87 can be brought into a block - diagonal form with @xmath88 independent blocks in the momentum space according to the famous bloch theorem @xcite . to understand this
, we consider the eigenvalue equation for the fermionic excitation spectrum in the coordinate space , which is known as the bdg equation . for our system ,
the bdg equation reads @xmath89 according to the bloch theorem , the solution of the eigenfunction @xmath90 takes the form of the so - called bloch function .
we have @xmath91 where @xmath92 is the momentum in the brillouin zone ( bz ) and the function @xmath93 has the same periodicity as the order parameter @xmath94 .
we therefore have the similar fourier expansion @xmath95 substituting this expansion into the bdg equation , for a given @xmath92 we obtain a matrix equation @xmath96 where the matrix @xmath97 is given by @xmath98 this shows that , for a given @xmath92-point in the bz , we can solve the eigenvalue spectrum @xmath99 by diagonalizing the matrix @xmath97 . without loss of generality
, the bz can be chosen as @xmath100 $ ] . for a quantized volume @xmath68 containing @xmath88 unit cells ,
we have @xmath88 allowed momenta @xmath92 in the bz .
accordingly , the grand potential is now given by @xmath101.\end{aligned}\ ] ] in the thermodynamic limit @xmath66 , the summation @xmath102 is replaced by an integral over the bz .
the hamiltonian matrix @xmath97 can be further simplified to lower the matrix size . after a proper rearrangement of the eigenvector @xmath103
, we find that @xmath87 can be decomposed into two blocks .
we have @xmath104 .
the blocks can be expressed as @xmath105 where @xmath106 is the identity matrix and the matrix @xmath107 is given by @xmath108 the eigenvalues of @xmath109 do not depend on the sign of @xmath34 . moreover , replacing the @xmath110 by @xmath111 amounts to a replacement of the eigenvalue spectrum @xmath112 by @xmath113 .
therefore , the two blocks contribute equally to the grand potential and we only need to determine the eigenvalues of @xmath109 .
the hamiltonian matrix ( [ highdensity ] ) represents the general problem of two - species pairing with mismatched fermi surfaces . in the weak coupling limit
, the pairing is dominated near the fermi surfaces .
therefore , the physical result should be universal in terms of the pairing gap @xmath3 at vanishing mismatch and the density of state @xmath17 at the fermi surface .
( lower panel ) for the ff state as a function of @xmath3 at @xmath114 mev .
the thin lines denote results in the weak - coupling limit .
the blue solid and red dashed lines correspond to @xmath115 mev and @xmath116 mev , respectively .
[ fig1],title="fig:",width=325 ] ( lower panel ) for the ff state as a function of @xmath3 at @xmath114 mev .
the thin lines denote results in the weak - coupling limit .
the blue solid and red dashed lines correspond to @xmath115 mev and @xmath116 mev , respectively .
[ fig1],title="fig:",width=321 ] in the following we shall focus on the zero - temperature case .
the grand potential @xmath78 is divergent and hence a proper regularization scheme is needed . since we need to deal with the bloch momentum @xmath117 ,
the usual three - momentum cutoff scheme @xcite is not appropriate for numerical calculations .
moreover , we are interested in the grand potential @xmath118 measured with respect to the normal state . therefore , we employ a pauli - villars - like regularization scheme , in which @xmath118 is well - defined @xcite .
the renormalized " grand potential is given by @xcite @xmath119 where @xmath120 with @xmath121 and @xmath122 . here
@xmath123 denotes the eigenvalue spectrum of @xmath109 .
the coupling constant @xmath43 can be fixed by the bcs gap @xmath3 at @xmath124 .
we expect that at weak coupling the physical results depend on the cutoff @xmath125 only through the bcs gap @xmath3 @xcite . in fig .
[ fig1 ] , we show the stability window for the ff state as a function of @xmath3 . in the weak coupling limit , the critical fields depend only on @xmath3 .
for accuracy reason @xcite , we shall choose @xmath126 mev at @xmath114 mev , which corresponds to the realistic value of @xmath3 at moderate density @xcite .
since the size of the ff window @xmath127 depends very weakly on @xmath3 and @xmath125 , we can use the upper critical field @xmath27 obtained in fig .
[ fig1 ] to calibrate " @xmath110 and appropriately extrapolate the results to the weak coupling limit .
for a given @xmath92-point in the bz , we can diagonalize the hamiltonian matrix @xmath109 to obtain its eigenvalue spectrum @xmath112
. the choice of the @xmath92-points in the bz should be dense enough to achieve the thermodynamic limit @xcite .
the eigenvalue equation can be rewritten as @xmath128 \phi_{\bf g}({\bf k}),\end{aligned}\ ] ] where the hamiltonian matrix @xmath129 reads @xmath130 here @xmath131 and we have used the fact @xmath132 .
the eigenstate @xmath103 includes two components @xmath133 and @xmath134 as usual in the bcs theory .
we have @xmath135 we notice that @xmath110 can be absorbed into the eigenvalues .
it is easy to prove that the eigenvalues of @xmath136 do not depend on the sign of @xmath34 .
moreover , if @xmath137 is an eigenvalue of @xmath136 , @xmath138 must be another eigenvalue .
therefore , replacing the @xmath110 by @xmath111 amounts to a replacement of the eigenvalue spectrum @xmath112 by @xmath113 .
however , the matrix @xmath107 has infinite dimensions because the integers @xmath139 run from @xmath140 to @xmath141 .
therefore , we have to make a truncation in order to perform a calculation .
it is natural to make a symmetrical truncation , i.e. , @xmath142 for sufficiently large @xmath143 , the contribution from the high - energy bands becomes vanishingly small and the grand potential @xmath118 converges to its precise value . after making this truncation , the matrix equation can be expressed as @xmath144 where @xmath7 and @xmath145 are @xmath146-dimensional vectors and @xmath147 are @xmath148 matrices .
the matrix elements of @xmath147 can be formally expressed as @xmath149,[l^\prime , m^\prime , n^\prime]}=-{\bf h}_{22}^{[l , m , n],[l^\prime , m^\prime , n^\prime ] } = \xi_{[l , m , n]}\delta_{l , l^\prime}\delta_{m , m^\prime}\delta_{n , n^\prime},\nonumber\\ & & { \bf h}_{12}^{[l , m , n],[l^\prime , m^\prime , n^\prime]}={\bf h}_{21}^{[l , m , n],[l^\prime , m^\prime , n^\prime ] } = \delta_{[l - l^\prime , m - m^\prime , n - n^\prime ] } , \label{elements}\end{aligned}\ ] ] where @xmath150}=\sqrt{\left(k_x+\frac{2\pi l}{a}\right)^2+\left(k_y+\frac{2\pi m}{a}\right)^2+\left(k_z+\frac{2\pi n}{a}\right)^2}-\mu.\end{aligned}\ ] ] here the matrix index @xmath151 $ ] corresponds to the reciprocal lattice vector @xmath152}=(2\pi / a)(l{\bf e}_x+m{\bf e}_y+n{\bf e}_z)$ ] .
it shows that the blocks @xmath153 and @xmath154 are diagonal . the off - diagonal blocks @xmath155 and @xmath156 carry the information of the order parameter @xmath34 and characterize the crystal structure . for a specific value of @xmath143 , we can write down the explicit form of the vectors @xmath7 and @xmath145 and the matrices @xmath147 . here
we use @xmath157 as an example .
the vectors @xmath7 and @xmath145 are @xmath158-dimensional can be expressed as @xmath159 } \\
u_{[-1,0 ] } \\ u_{[-1,1 ] } \\ u_{[0,-1 ] } \\ u_{[0,0 ] } \\ u_{[0,1 ] } \\ u_{[1,-1 ] } \\ u_{[1,0 ] } \\
u_{[1,1]}\end{array}\right),\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \upsilon=\left(\begin{array}{cc } \upsilon_{[-1,-1 ] } \\ \upsilon_{[-1,0 ] } \\ \upsilon_{[-1,1 ] } \\ \upsilon_{[0,-1 ] } \\ \upsilon_{[0,0 ] } \\ \upsilon_{[0,1 ] } \\ \upsilon_{[1,-1 ] } \\ \upsilon_{[1,0 ] } \\ \upsilon_{[1,1 ] } \end{array}\right),\end{aligned}\ ] ] where @xmath160}$ ] and @xmath161}$ ] are defined as @xmath162}=\left(\begin{array}{cc } u_{[l , m,-1 ] } \\
u_{[l , m,0 ] } \\
u_{[l , m,1]}\end{array}\right),\ \
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \upsilon_{[l , m]}=\left(\begin{array}{cc } \upsilon_{[l , m,-1 ] }
\\ \upsilon_{[l , m,0 ] }
\\ \upsilon_{[l , m,1 ] } \end{array}\right).\end{aligned}\ ] ] in this representation , the off diagonal blocks @xmath155 and @xmath156 are given by @xmath163 for bcc structure and @xmath164 for fcc structure , respectively .
here the blocks @xmath165 and @xmath166 are defined as @xmath167 in principle , the eigenvalue spectrum @xmath112 can be obtained by diagonalizing the matrix @xmath168 with a size @xmath169 .
we notice that the matrix size @xmath169 grows dramatically with increasing cutoff @xmath143 .
therefore , for realistic diagonalization , it is better to reduce the size of the matrix .
here we find that , with a proper rearrangement of the basis @xmath170 or after a similarity transformation , the matrix @xmath168 becomes block diagonal .
we have @xmath171 where size of the blocks @xmath172 and @xmath173 are both @xmath146 .
the eigenvector @xmath170 is now defined as @xmath174 for @xmath157 , the @xmath158-dimensional vectors @xmath175 and @xmath176 are given by @xmath177 } \\
u_{[-1,-1,0 ] } \\ \upsilon_{[-1,-1,1 ] } \\ u_{[-1,0,-1 ] } \\ \upsilon_{[-1,0,0 ] } \\ u_{[-1,0,1 ] } \\ \upsilon_{[-1,1,-1 ] } \\ u_{[-1,1,0 ] } \\ \upsilon_{[-1,1,1 ] } \\ u_{[0,-1,-1 ] } \\ \upsilon_{[0,-1,0 ] } \\ u_{[0,-1,1 ] } \\ \upsilon_{[0,0,-1 ] } \\ u_{[0,0,0 ] } \\ \upsilon_{[0,0,1]}\\ u_{[0,1,-1 ] } \\ \upsilon_{[0,1,0 ] } \\ u_{[0,1,1 ] } \\ \upsilon_{[1,-1,-1 ] } \\ u_{[1,-1,0 ] } \\ \upsilon_{[1,-1,1 ] } \\ u_{[1,0,-1 ] } \\ \upsilon_{[1,0,0 ] } \\ u_{[1,0,1 ] } \\ \upsilon_{[1,1,-1 ] } \\ u_{[1,1,0 ] } \\
\upsilon_{[1,1,1]}\end{array}\right ) , \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \phi_-=\left(\begin{array}{cc } u_{[-1,-1,-1 ] } \\ \upsilon_{[-1,-1,0 ] } \\ u_{[-1,-1,1 ] } \\ \upsilon_{[-1,0,-1 ] } \\u_{[-1,0,0 ] } \\ \upsilon_{[-1,0,1 ] } \\ u_{[-1,1,-1 ] } \\ \upsilon_{[-1,1,0 ] } \\ u_{[-1,1,1 ] } \\ \upsilon_{[0,-1,-1 ] } \\ u_{[0,-1,0 ] } \\ \upsilon_{[0,-1,1 ] } \\ u_{[0,0,-1 ] } \\ \upsilon_{[0,0,0 ] } \\ u_{[0,0,1]}\\ \upsilon_{[0,1,-1 ] } \\ u_{[0,1,0 ] } \\ \upsilon_{[0,1,1 ] } \\ u_{[1,-1,-1 ] } \\ \upsilon_{[1,-1,0 ] } \\ u_{[1,-1,1 ] } \\ \upsilon_{[1,0,-1 ] } \\ u_{[1,0,0 ] } \\ \upsilon_{[1,0,1 ] } \\ u_{[1,1,-1 ] } \\ \upsilon_{[1,1,0 ] } \\ u_{[1,1,1]}\end{array}\right),\end{aligned}\ ] ] which is just a proper rearrangement of the original basis given by ( [ basis ] ) .
the blocks @xmath172 and @xmath173 are given by @xmath178 where @xmath155 is given by ( [ elements ] ) or ( [ mbcc ] ) and ( [ mfcc ] ) for @xmath157 .
@xmath179 is a diagonal matrix containing the kinetic energies @xmath180}$ ] .
we have @xmath181,[l^\prime , m^\prime , n^\prime ] } = ( -1)^{l+m+n}\xi_{[l , m , n]}\delta_{l , l^\prime}\delta_{m , m^\prime}\delta_{n , n^\prime}.\end{aligned}\ ] ] for @xmath157 , we obtain @xmath182},\xi_{[-1,-1,0]},-\xi_{[-1,-1,1]},\cdots,\nonumber\\ & & \ \ \ \ \ \ \ \ \xi_{[0,0,0]},\cdots,-\xi_{[1,1,-1]},\xi_{[1,1,0]},-\xi_{[1,1,1]}).\end{aligned}\ ] ] it is easy to show that the eigenvalue spectra of @xmath172 and @xmath173 are dependent : if the eigenvalue spectrum of @xmath172 is given by @xmath183 , the eigenvalue spectrum of @xmath173 reads @xmath184 .
therefore , we only need to diagonalize the matrix @xmath172 or @xmath173 which has a size @xmath146 .
once the eigenvalue spectrum of @xmath172 is known , the eigenvalue spectrum of hamiltonian matrix @xmath109 is given by @xmath185 therefore , we can in principle calculate the potential landscape @xmath186 .
the solution @xmath187 of a specific crystal structure corresponds to the global minimum of the potential landscape .
to achieve satisfying convergence we normally need a large cutoff @xmath143
. however , the matrix size @xmath146 and hence the computing time and cost grow dramatically with increasing @xmath143 .
the cutoff @xmath143 needed for convergence can be roughly estimated from the maximum momentum @xmath188 in the matrix , @xmath189 the value of @xmath188 can be estimated from the lo state .
the calculation of the lo state is much easier than 3d structures because the matrix size becomes @xmath190 .
the details of the calculation of the lo state are presented in appendix b. for @xmath126 mev we need @xmath191gev @xcite .
since we are interested in the region @xmath192 $ ] and the optimal pair momentum is @xmath193 , we estimate @xmath194 for bcc and @xmath195 for fcc .
these huge matrix sizes are beyond the capability of our current computing facilities . on the other hand , even though a supercomputer may be able to diagonalize these huge matrices , the computing time and cost are still enormous , which makes the calculation infeasible . .
[ fig3],width=328 ] since we are interested in the grand potential @xmath118 rather than the band structure ( the eigenvalues ) , we can neglect a small amount of the off - diagonal couplings @xmath34 in the matrix @xmath172 . by doing so
, the huge matrix @xmath172 can be decomposed into a number of blocks with size @xmath196 . for symmetry reason , we set the centers of these blocks at the reciprocal lattice vectors @xmath197}=(2d+1)\frac{2\pi}{a}(n_x{\bf e}_x+n_y{\bf e}_y+n_z{\bf e}_z)\ ] ] with @xmath198 . with increasing @xmath8
, the grand potential converges to the result from exact diagonalization .
convergence is normally reached at some value @xmath199 .
the details of our computational scheme are presented in appendix c. if the block size @xmath200 is within our computing capability , the calculation becomes feasible .
fortunately , we find that this computational scheme works for the bcc structure . at present , we are not able to perform a calculation for the fcc structure , since the value of @xmath201 needed for convergence is much larger .
note that the computing cost is still very large even though we have employed this effective computational scheme .
we have performed calculations of the bcc structure for @xmath202 mev @xcite at @xmath114 mev @xcite . for different values of @xmath3 ,
the results are almost the same in terms of the quantity @xmath203 .
therefore , we anticipate that our results can be appropriately extrapolated to the weak coupling limit @xmath204 . in the following ,
we shall present the result for @xmath205 mev . for a given value of @xmath206
, we calculate the potential curve @xmath207 at various values of @xmath208 and search for the optimal pair momentum and the minimum of the potential landscape .
the potential curves at the optimal pair momenta for several values of @xmath206 are shown in fig .
[ fig2 ] . with increasing value of @xmath206 , the potential minimum gets shallower . at a critical value @xmath209 , the potential minimum approaches zero and a first - order phase transition to the normal state occurs .
the comparison of the grand potentials of various phases are shown in fig .
[ fig3 ] . for the lo state ,
its phase transition to the normal state occur almost at the same point as the ff state , @xmath210 . at @xmath211 ,
the grand potential of the bcc structure is negative , which indicates that the bcc structure is energetically favored around the ff - normal transition point .
well below the ff - normal transition point , the bcc state has higher grand potential than the lo state and hence is not favored . near the bcs - lo transition ,
the solitionic state becomes favored @xcite . however
, this does not change our qualitative conclusion .
our result is qualitatively consistent with the gl analysis @xcite .
however , the quantitative difference is significant : the gl analysis predicts a strong first - order phase transition and a large upper critical field @xcite , while our result shows a weak first - order phase transition at which @xmath28 . on the other hand ,
our result is quantitatively compatible with the quasiclassical equation approach @xcite , where it shows that the bcc structure is preferred in a narrow window around @xmath211 at zero temperature @xcite .
therefore , the gl analysis up to the order @xmath15 may not be quantitatively sufficient .
we notice that the lo state already shows the limitation of the gl analysis : while the gl analysis predicts a second - order phase transition , exact calculation shows a first - order phase transition @xcite ( see also appendix b ) . in the future ,
it is necessary to study the higher - order expansions and the convergence property of the gl series , which would help to quantitatively improve the gl predictions .
in summary , we have performed an solid - state - like calculation of the ground - state energy of a 3d structure in crystalline color superconductivity .
we proposed a computational scheme to overcome the difficulties in diagonalizing matrices of huge sizes .
our numerical results show that the bcc structure is preferred in a small window around the conventional ff - normal phase transition point , which indicates that the higher - order terms in the gl approach are rather important . in the future it would be possible to perform a calculation for the fcc structure with stronger computing facilities and/or with better method of matrix diagonalization .
this solid - state - like approach can also be applied to study the crystalline structures of the three - flavor color - superconducting quark matter @xcite and the inhomogeneous chiral condensate @xcite .
_ acknowledgments _ we thank profs .
mark alford , joseph carlson , roberto casalbuoni , stefano gandolfi , hui hu , xu - guang huang , massimo mannarelli , sanjay reddy , armen sedrakian , and shiwei zhang for useful discussions and comments .
the work of g. c. and p. z. was supported by the nsfc under grant no .
11335005 and the most under grant nos . 2013cb922000 and 2014cb845400 .
the work of l. h. was supported by the us department of energy topical collaboration
neutrinos and nucleosynthesis in hot and dense matter " .
l. h. also acknowledges the support from frankfurt institute for advanced studies in the early stage of this work .
the numerical calculations were performed at tsinghua national laboratory for information science and technology .
in the ginzburg - landau ( gl ) theory of crystalline color superconductors at zero temperature and at weak coupling , the grand potential measured with respect to the normal state , @xmath212 , is expanded as @xcite @xmath213 where @xmath17 is the density of state at the fermi surface .
the coefficient @xmath214 is universal for all crystal structures and is given by @xcite @xmath215 + let us consider the vicinity of the conventional loff - normal transition point @xmath211 , where we have @xmath216 at the pair momentum @xmath18 , we obtain @xmath217 for convenience , we make the gl potential dimensionless by using the variables @xmath218 , @xmath219 , @xmath220 , @xmath221 , and @xmath222 .
we have @xmath223 the gl coefficients @xmath224 and @xmath225 for a number of crystalline structures were first calculated by bowers and rajagopal @xcite .
the predictions for the nature of the phase transitions were normally based on the gl potential up to the sixth order ( @xmath226 ) . to our knowledge , the higher order gl coefficients have never been calculated . here
we show that the higher - order gl expansions are important for the prediction of the phase transition . to be specific ,
let us consider the bcc structure .
its gl coefficients @xmath224 and @xmath225 have been evaluated as @xcite @xmath227 since @xmath228 , the phase transition to the normal state should be of first order . if we employ the gl potential up to the sixth order , we predict a strong first - order phase transition at @xmath229 .
let us turn on the eighth - order term and study how the size of the coefficient @xmath230 influences the quantitative prediction of the phase transition . in fig .
[ glbcc ] , we show the gl potential curves for two different values of @xmath230 at @xmath211 . for vanishing @xmath230 , the potential curve develops a deep minimum @xmath231 at @xmath232 , which indicates a strong first - order phase transition at @xmath233 .
however , for a large value @xmath234 , we find a shallow minimum @xmath235 located at @xmath236 . in fig .
[ glbcc2 ] , we show the gl potential curves at the first - order phase transition point @xmath29 . for @xmath237
we find a strong first - order phase transition at @xmath229 , where the minima located at @xmath238 and @xmath239 become degenerate .
for @xmath234 , however , we observe a much weaker first - order phase transition at @xmath240 , where the degenerate minima are located at @xmath238 and @xmath241 .
these results clearly show that , for larger @xmath230 , the first - order phase transition becomes weaker . for @xmath242
, we expect that @xmath243 . on the other hand ,
if @xmath230 is small or even negative , then the next order @xmath244 would become important .
the order parameter of the lo state is given by @xmath245 it is periodic along the @xmath246 direction with the periodicity @xmath55 .
so it can be decomposed into a discrete set of fourier components , @xmath247 the fourier component @xmath248 is given by @xmath249 the matrix equation takes a similar form as the 3d structures .
we have @xmath250 \phi_n({\bf k}),\end{aligned}\ ] ] where the hamiltonian matrix @xmath251 reads @xmath252 with @xmath253 we notice that only the motion in the @xmath246 direction becomes quantized .
the bz for @xmath254 can be defined as @xmath255 or @xmath256 .
the eigenstate @xmath257 includes two components @xmath258 and @xmath259 .
we have @xmath260 if @xmath137 is an eigenvalue of @xmath136 , @xmath138 must be another eigenvalue . therefore , replacing the @xmath110 by @xmath111 amounts to a replacement of the eigenvalue spectrum @xmath112 by @xmath113 . after a truncation @xmath261
, we obtain a finite matrix equation @xmath262 where @xmath7 and @xmath145 are @xmath263-dimensional vectors and @xmath147 are @xmath264 matrices . for a specific value of @xmath143 , we can write down the explicit form of the vectors @xmath7 and @xmath145 and the matrices @xmath147 . here
we use @xmath265 as an example .
the vectors @xmath7 and @xmath145 are @xmath266-dimensional can be expressed as @xmath267 the matrices @xmath147 can be explicitly written as @xmath268 the eigenvalue spectrum @xmath112 can be obtained by diagonalizing the matrix @xmath168 with a size @xmath269 . with a proper rearrangement of the basis @xmath170 or a similarity transformation , we have @xmath171 where the sizes of @xmath172 and @xmath173 are both @xmath190 .
the basis @xmath170 is now defined as @xmath174 for @xmath265 , the @xmath266-dimensional vectors @xmath175 and @xmath176 are given by @xmath270 the blocks @xmath172 and @xmath173 can be expressed as @xmath271 @xmath179 is a diagonal matrix containing the kinetic energies .
we have @xmath272 the eigenvalue spectra of @xmath172 and @xmath173 are dependent : if the eigenvalue spectrum of @xmath172 is given by @xmath183 , the eigenvalue spectrum of @xmath173 reads @xmath184 .
therefore , we need only to diagonalize the matrix @xmath172 or @xmath173 which has a dimension @xmath190 .
once the eigenvalue spectrum of @xmath172 is known , the eigenvalue spectrum of hamiltonian matrix @xmath109 is given by @xmath273 .
the thermodynamic potential of the lo state at zero temperature can be expressed as @xmath274 similar pauli - villas - like regularization scheme should be applied finally . in fig .
[ lo ] ( a ) , we show the grand potential of the lo state for @xmath275 mev . the grand potential for the self - consistent 1d modulation for @xmath275 mev was also reported in @xcite .
we find that the results for the lo state and the self - consistent 1d modulation agrees with each other near the phase transition to the normal state . near the bcs - lo transition point , the self - consistent 1d modulation has lower grand potential than the lo state .
it was shown in @xcite that the self - consistent 1d modulation forms a soliton lattice structure near the lower critical field , which lowers the grand potential of the system .
near the upper critical field the gap function becomes sinusoidal , and therefore the grand potentials of the lo state and the 1d modulation agree with each other .
we notice that the phase transition from the lo state to the normal state is of first order , which is in contradiction to the prediction from the gl analysis . to understand the reason , we show in fig .
[ lo ] ( b ) the potential curve at @xmath276 and at the optimal pair momentum @xmath277 .
we find that the potential curve has two minima : a shallow minimum at @xmath278 and a deep minimum at @xmath279 .
obviously , the shallow minimum is responsible for the gl theory which predicts a second - order phase transition .
however , the deep global minimum , which can not be captured by the gl theory up to the order @xmath226 , is responsible for the real first - order phase transition
. therefore , the lo state already shows the importance of the higher - order expansions in the gl theory .
the key problem in the numerical calculation is the diagonalization of the matrix @xmath172 or @xmath173 and obtaining all the eigenvalues . for bcc and fcc structures , we use a symmetrical truncation @xmath280 with a large cutoff @xmath281 .
however , the matrix size grows dramatically with increasing cutoff @xmath143 , which makes the calculation infeasible because of not only the computing capability of current computing facilities but also the computing time and cost .
notice that we need to diagonalize the matrix @xmath172 for various values of the momentum @xmath92 in the bz , the gap parameter @xmath34 , and the pair momentum @xmath208 .
we first estimate the size of @xmath143 needed for the convergence of the grand potential @xmath118 .
the matrix size @xmath146 and hence the computing time and cost grow dramatically with increasing @xmath143 .
the cutoff @xmath143 is related to the maximum momentum @xmath188 in each direction ( @xmath282 , @xmath283 , and @xmath246 ) .
we have @xmath284 this maximum momentum can be roughly estimated from the calculation of the lo state . for the lo state , the matrix size becomes @xmath190 and exact diagonalization is possible .
the regime of @xmath110 we are interested in is @xmath285 $ ] and the optimal pair momentum is located at @xmath286 . from the calculation of the lo state at @xmath126 mev , we find that @xmath188 must reach at least @xmath266gev for convergence .
notice that we have @xmath287 for bcc and @xmath288 for fcc .
therefore , the cutoff @xmath143 for bcc can be estimated as @xmath194 , which corresponds to a matrix size @xmath289 .
for fcc , the cutoff is even larger because of the factor @xmath290 .
we have @xmath195 for fcc , which corresponds to a matrix size @xmath291 .
notice that this is only a naive estimation . in practice ,
the cutoff needed for convergence may be smaller or larger .
exact diagonalization of such huge matrices to obtain all the eigenvalues are impossible with our current computing facility .
we therefore need a feasible scheme to evaluate the grand potential @xmath118 .
notice that decreasing the value of @xmath3 does not reduce the size of the matrices . in this case , even though @xmath188 becomes smaller , the pair momentum @xmath208 also gets smaller .
let us call an off - diagonal element @xmath34 in @xmath172 or @xmath173 a coupling " . because our goal is to evaluate the grand potential @xmath118 rather than to know exactly all the band dispersions ( eigenvalues ) , we may neglect a small amount of couplings to lower the size of the matrices . by neglecting this small amount of couplings ,
the huge matrix @xmath172 becomes block diagonal with each block having a much smaller size .
in general , we expect that the omission of a small amount of couplings @xmath34 induces only a perturbation to the grand potential @xmath118 .
we shall call this scheme small block method ( sbm ) . to be specific , the size of the small blocks in our calculation is @xmath196 with @xmath292 . in general
, we have @xmath293 . for symmetry reason
, we require that the centers of these blocks are located at the reciprocal lattice vectors @xmath294}=(2d+1)\frac{2\pi}{a}(n_x{\bf e}_x+n_y{\bf e}_y+n_z{\bf e}_z)\end{aligned}\ ] ] with @xmath198 . this scheme makes the sbm feasible even though @xmath146 is not divisible by @xmath196 . in practice , we first choose a large cutoff @xmath143 which is sufficient for convergence . by increasing the value of @xmath8 , we find that the grand potential @xmath118 finally converges . in practice ,
if the grand potentials evaluated at several values of @xmath8 , i.e. , @xmath295 , @xmath296 , ... , and @xmath201 ( @xmath297 ) , are very close to each other , we identify that the grand potential converges to its precise value from exact diagonalization . at the converging value @xmath199 , the block size @xmath200 is normally much smaller than the total size @xmath146 .
this scheme makes the calculation feasible and also saves a lot of computing time and cost .
the matrices for the 3d structures are huge and can not be written down here . for the sake of simplicity
, let us use the lo state as a toy example for the sbm . in this case , the matrix size and the block size are @xmath190 and @xmath298 , respectively .
the centers of the blocks are located at the reciprocal lattice vectors @xmath299 with @xmath300 . for @xmath301 ,
the matrix @xmath172 reads therefore , by neglecting a small amount of couplings , we have made the large matrix @xmath172 block - diagonal .
notice that this is only a toy example for the sbm . in practice , @xmath301 and @xmath304 is obviously not enough for convergence . for the lo state , exact diagonalization of the matrices at @xmath286
is quite easy because the size of the matrices is @xmath190 .
we can therefore check the error induced by the sbm . the relative error induced by the sbm
can be defined as @xmath306 where @xmath307 and @xmath308 are the grand potentials obtained from the sbm and exact diagonalization , respectively . in fig .
[ error ] ( a ) , we show a numerical example of the relative error for the lo state at @xmath309 and @xmath310 . in the calculations , we use @xmath311 and @xmath312 .
we find that the relative error is very small , generally of order @xmath313 .
the slightly larger error around @xmath314 is due to the fact that @xmath118 itself is very small there .
for the bcc structure , we are not able to check the relative error at @xmath286 because it is impossible to exactly diagonalize the matrices with a huge size @xmath146
. however , we can check the @xmath8 dependence of the grand potential .
for pair momentum around @xmath286 , we choose a sufficiently large cutoff @xmath143 and increase the value of @xmath8 .
we evaluate the grand potentials for various values of @xmath8 ( i.e. , @xmath295 , @xmath296 , ... , and @xmath201 ) .
if they are very close to each other , we identify that the grand potential converges .
then the grand potential @xmath118 can be evaluated at @xmath199 . in fig .
[ error ] , we show the @xmath8 dependence of the grand potential of the bcc structure at @xmath315 , @xmath316 , and @xmath317 . in the calculation
we choose @xmath311 which is sufficiently large to guarantee the convergence at large @xmath59 .
we find that for bcc structure , @xmath201 is normally within the range @xmath318 , which is feasible for a calculation . for fcc structure ,
we do not find a satisfying convergence at these small values of @xmath8 . | it is generally believed that the inhomogeneous larkin - ovchinnikov - fulde - ferrell ( loff ) phase appears in a color superconductor when the pairing between different quark flavors is under the circumstances of mismatched fermi surfaces .
however , the real crystal structure of the loff phase is still unclear because an exact treatment of 3d crystal structures is rather difficult . in this work we present a solid - state - like calculation of the ground - state energy of the body - centered cubic ( bcc ) structure for two - flavor pairing by diagonalizing the hamiltonian matrix in the bloch space without assuming a small amplitude of the order parameter .
we develop a computational scheme to overcome the difficulties in diagonalizing huge matrices .
our results show that the bcc structure is energetically more favorable than the 1d modulation in a narrow window around the conventional loff - normal phase transition point , which indicates the significance of the higher - order terms in the ginzburg - landau approach . |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Small Business Regulatory Assistance
Act of 1998''.
SEC. 2. PURPOSE.
The purpose of this Act is to establish a system of confidential
voluntary compliance with Federal regulations that will--
(1) provide a low-cost process to significantly improve
voluntary compliance by small business concerns with Federal
regulations;
(2) improve the level of outreach to the small business
community; and
(3) provide for unbiased feedback to Federal agencies on
the small business regulatory environment.
SEC. 3. ESTABLISHMENT OF PROGRAM.
The Small Business Act (15 U.S.C. 637 et seq.) is amended by
inserting after section 21A the following:
``SEC. 21B. SMALL BUSINESS REGULATORY RELIEF.
``(a) Definitions.--In this section:
``(1) Assistant administrator.--The term `Assistant
Administrator' means the Assistant Administrator for Small
Business Development Centers of the Administration.
``(2) Compliance assistance plan.--The term `compliance
assistance plan' means a 5-year plan jointly developed and
revised annually by each participating agency, the Assistant
Administrator, and representatives of an association
representing a majority of small business development centers,
for the establishment and maintenance of the system of
voluntary compliance.
``(3) Participating agency.--The term `participating
agency' means--
``(A) the Internal Revenue Service of the
Department of the Treasury;
``(B) the Environmental Protection Agency; and
``(C) the Department of Labor.
``(4) Small business development center.--The term `small
business development center'--
``(A) means a small business development center
established pursuant to section 21; and
``(B) includes a consortium of 2 or more small
business development centers.
``(5) System of voluntary compliance.--The term `system of
voluntary compliance' means a system under which small business
development centers provide confidential assistance to 1 or
more small business concerns in achieving voluntary compliance
with regulatory requirements imposed on small business concerns
by a participating agency.
``(b) Duties of the Participating Agency--
``(1) Compliance assistance plan.--Not later than 90 days
after the enactment of the Small Business Regulatory Assistance
Act of 1998 and annually thereafter, each participating agency,
the Assistant Administrator, and representatives of an
association representing a majority of small business
development centers, shall agree to a compliance assistance
plan.
``(2) Contents of the compliance assistance plan.--The
compliance assistance plan agreed to under paragraph (1) shall
include--
``(A) the regulatory compliance objectives of each
participating agency;
``(B) the regulatory compliance priorities of each
participating agency;
``(C) identification of the types of services,
materials, and resources to be developed or used by
each participating agency;
``(D) identification of facilities, expertise, and
other resources of each participating agency that may
be accessed by the Assistant Administrator, a small
business development center, or a small business
concern participating in the system of voluntary
compliance established under this section; and
``(E) performance outcome measures and evaluation
criteria to be used by each participating agency in
evaluating the effectiveness of the system of voluntary
compliance established under this section.
``(c) Duties of the Office of Small Business Development Centers.--
``(1) Implementation and administration of the compliance
assistance plan.--
``(A) In general.--Based on the compliance
assistance plan agreed to under subsection (b)(1), not
later than 180 days after the date of enactment of the
Small Business Regulatory Assistance Act of 1998, the
Assistant Administrator, with the agreement of an
association representing a majority of small business
development centers, shall develop and publish
guidelines for the establishment by small business
development centers of the system of voluntary
compliance in accordance with this section.
``(B) Guideline requirements.--The guidelines
published under subparagraph (A) shall--
``(i) establish priorities for the types of
assistance to be provided to small business
concerns under the system of voluntary
compliance established by small business
development centers under this section; and
``(ii) establish standards relating to
educational, technical, and support services
required by small business development centers
to provide a system of voluntary compliance.
``(C) Program delivery.--The guidelines established
under subparagraph (A) shall--
``(i) require that the assistance to small
business concerns participating in the system
of voluntary compliance under this section to
be carried out by small business development
centers, which shall, to the maximum extent
practicable, access other existing Federal and
State nonpunitive, compliance and technical
assistance programs, including, but not limited
to, the technical and environmental compliance
assistance programs established under section
507 of the Clean Air Act Amendments of 1990;
and
``(ii) provide that certain national
service delivery and support requirements be
carried out under contract with an association
representing the majority of small business
development centers.
``(D) Issuance of grant.--Not later than 150 days
after the submission of work plans under subsection
(d)(1), the Assistant Administrator shall make a grant
to each small business development center to carry out
the system of voluntary compliance.
``(d) Duties of Small Business Development Centers.--
``(1) Work plan.--Beginning not later that 60 days after
the date on which the guidelines are published by the Assistant
Administrator under subsection (c)(1)(A), each small business
development center shall, on an annual basis, submit to the
Assistant Administrator a work plan under which the small
business development center will carry out the system of
voluntary compliance in accordance with such guidelines.
``(2) Assistance provided.--
``(A) In general.--Subject to subparagraph (B), the
assistance to small business concerns participating in
the system of voluntary compliance shall include--
``(i) access to information and resources;
``(ii) training and educational activities;
``(iii) confidential, free-of-charge, one-
on-one in-depth counseling;
``(iv) technical assistance; and
``(v) referrals to experts.
``(B) Exception for legal services.--No small
business development center (or any person relied on by
a small business development center in providing
assistance under this section) shall provide legal
services, other than the provision of basic business
law information, without the endorsement of the State
Bar Association of each State in which the small
business development center (or any person relied on by
a small business development center in providing
assistance under this section) are providing services
under this section.
``(3) Reports; recommendations--
``(A) In general.--Each small business development
center receiving assistance under this section shall,
on an annual basis, submit to the Assistant
Administrator a report on the assistance provided by
the small business development center under this
section.
``(B) Privacy protection.--No small business
development center (or any person relied on by a small
business development center in providing assistance
under this section) shall be required to disclose the
name or address of any small business concern
participating in the system of voluntary compliance
under this section.
``(C) Audits.--Subparagraph (B) shall not be
construed to prevent the Assistant Administrator or the
Inspector General of the Administration from auditing a
small business development center (or any person relied
on by a small business development center in providing
assistance under this section).
``(e) Evaluations.--
``(1) Annual report.--The Assistant Administrator shall, on
an annual basis, submit to the Committees on Small Business of
the Senate and the House of Representatives and to the
Regulatory Fairness Board established under section 29 a
report, which shall include--
``(A) a description of the types of assistance
provided by small business development centers to small
business concerns participating in the system of
voluntary compliance;
``(B) the level of outreach to small business
concerns achieved by small business development centers
under this section; and
``(C) recommendations for improvements in the
regulation of small business concerns participating in
the system of voluntary compliance.
``(2) Independent national assessment.--Upon the expiration
of the 3-year period beginning on the date on which a majority
of small business development centers have received grants to
begin implementation of the work plans described under
subsection (d)(1), the Comptroller General of the United States
shall provide for an evaluation of the system of voluntary
compliance established under this section which shall be
submitted to the Committees on Small Business of the Senate and
the House of Representatives.
``(f) Funding.--
``(1) In general.--Subject to paragraph (2), the total
amount received under this section in any fiscal year by small
business development centers located in a State shall not
exceed the sum of--
``(A) the State's pro rata share of the amount made
available under subsection (g), based on the population
of the State as compared to the total population in the
United States; and
``(B) $300,000.
``(2) Exception.--Amounts made available to a small
business development center by the Administration or another
agency to carry out section 21(c)(3)(G) shall not be included
in the calculation of maximum funding of a small business
development center under paragraph (1).
``(3) Exemption from matching requirement.--Amounts made
available to a small business development center under this
section shall not be subject to the matching funds requirements
or the eligibility requirements of section 21(a)(4).
``(4) Certification requirement.--
``(A) In general.--Subject to subparagraph (B),
after September 30, 2000, the Assistant Administrator
may not make any amount available under this section to
a small business development center, unless the small
business development center (or with respect to a
consortium of small business development centers
receiving assistance under this section as a single
grantee, each center within consortium) has been
approved under the certification program under section
21(k)(2).
``(B) Waiver.--The Associate Administrator may
waive the requirements of subparagraph (A) with respect
to a small business development center if the Associate
Administrator determines that the small business
development center is making a good faith effort to
obtain the certification described in subparagraph (A).
``(5) Administrative costs.--Not more than 2 percent of the
amount made available under subsection (g) in each fiscal year
may be used by the Assistant Administrator for the costs of
administration, evaluation, and reporting under this section.
``(g) Authorization of Appropriations.--There are authorized to be
appropriated to carry out this section--
``(1) $40,000,000 for fiscal year 1999;
``(2) $50,000,000 for fiscal year 2000;
``(3) $62,000,000 for fiscal year 2001; and
``(4) $77,000,000 for fiscal year 2002.''. | Small Business Regulatory Assistance Act of 1998 - Amends the Small Business Act to require each participating Federal agency (the Internal Revenue Service, Environmental Protection Agency, and Department of Labor), the Assistant Administrator for Small Business Development Centers of the Small Business Administration, and representatives of an association representing a majority of small business development centers (SBDCs) to agree to a small business regulatory compliance assistance plan.
Directs the Assistant Administrator to develop and publish guidelines for the establishment by SBDCs of a system of small business voluntary regulatory compliance (system), with specified guideline requirements. Outlines the assistance to be provided to participating small businesses, with an exception concerning legal services.
Requires annual reports from: (1) each SBDC to the Assistant Administrator on assistance provided; and (2) the Assistant Administrator to the House and Senate Small Business Committees and the Regulatory Fairness Board concerning the assistance provided under this Act, the level of outreach to small businesses achieved by SBDCs, and recommendations for improvements in the regulation of small businesses participating in the system. Directs the Comptroller General to evaluate the system and submit findings to such Committees.
Provides State funding limits for such assistance, with exceptions and an exemption from matching requirements.
Prohibits the Assistant Administrator from providing any funds to an SBDC after September 30, 2000, unless such SBDC has been approved for funding under a certification requirement (with a waiver for a good faith effort to achieve such certification).
Authorizes appropriations for FY 1999 through 2002. |
let @xmath0 be two natural numbers satisfying the stable condition @xmath1 , and @xmath2 be the moduli space of stable curves with genus @xmath3 and @xmath4 marked points . denote by @xmath5 ( @xmath6 ) the first chern class of the @xmath7-th tautological line bundle @xmath8 on @xmath2 , and denote by @xmath9 ( @xmath10 ) the @xmath11-th chern class of the hodge bundle @xmath12 on @xmath2 .
the hodge integrals are defined as the following integrals : @xmath13 they arise naturally in the localization computation of gromov - witten invariants for toric varieties , and are also related to many interesting mathematical objects , like hurwitz numbers , irreducible representations of symmetric groups , and so on @xcite .
denote by @xmath14 the @xmath11-th chern character of the hodge bundle @xmath12 on @xmath2 .
they are polynomials of @xmath15 , and satisfy @xmath16 becuase of the mumford relation @xcite .
the genus @xmath3 free energy for hodge integrals are defined as the following generating series @xmath17 and the full genera free energy and the partition function are defined as @xmath18 we proved in @xcite that the function @xmath19 , where @xmath20 , satisfies a family of partial differential equations @xmath21 where @xmath22 are differential polynomials , and these equations form a hamiltonian integrable hierarchy , which is called the hodge hierarchy . in particular , when @xmath23 , the hodge hierarchy is just the korteweg - de vries ( kdv ) hierarchy , so the hodge hierarchy is actually a deformation of the kdv hierarchy with @xmath24 s as deformation parameters .
when @xmath24 s equal to other values , the hodge hierarchy may coincide with some known integrable systems .
for example , if @xmath25 then we have @xmath26 where @xmath27 is the chern polynomial of the hodge bundle @xmath12 given by @xmath28 so the corresponding partition function @xmath29 is also called the partition function for _ linear hodge integrals_. it is proved by buryak in @xcite that the hodge hierarchy for linear hodge integrals is equivalent to the intermediate long wave ( ilw ) hierarchy .
if we take @xmath30 then we have @xmath31 we conjectured and proved the following theorem in @xcite and @xcite respectively : introduce a shift operator @xmath32 , and define @xmath33 then we have @xmath34 more generally , @xmath35 is given by the @xmath7-th equation of the volterra lattice hierarchy ( also called the discrete kdv hierarchy ) , @xmath36,\ ] ] where @xmath37 .
the hodge integrals that appear in belong to the class of _ special cubic hodge integrals _
, whose general form is given by @xmath38 where @xmath39 satisfy the so - called _ local calabi - yau condition _
@xmath40 the special cubic hodge integrals arise in the localization computation of gromov - witten invariants for toric calabi - yau threefolds , so they are very important in the study of mirror symmetry and other related areas .
therefore , the analogue of the above theorem for more general special cubic hodge integrals is an important problem .
let us take @xmath41 then we have @xmath42 let us denote @xmath43 and define @xmath44 boris dubrovin and di yang showed in @xcite that the function @xmath45 satisfies , at the approximation up to @xmath46 , the following equation @xmath47 they found that this equation is a certain reduction of the semi - discrete 2d toda lattice @xcite , and they conjectured that @xmath45 should satisfy a certain reduction of the integrable hierarchy associated to the semi - discrete 2d toda lattice . by continuing dubrovin - yang s calculation , it can be shown that at the approximation up to @xmath46 the function @xmath45 also satisfies the following equation @xmath48 where @xmath49 is given by @xmath50 note that the roles played by @xmath51 and @xmath52 are symmetric , so , if we introduce @xmath53 and exchange @xmath51 and @xmath52 , we obtain @xmath54 which implies that @xmath55 one can also obtain @xmath56 by using a similar argument .
the purpose of the present paper is to give a precise statement of dubrovin - yang s conjecture on the integrable hierarchy that governs the cubic hodge integrals satisfying the local calabi - yau condition .
we will give the definition of the integrable hierarchy in terms of lax pair representation , study its hamiltonian structure and tau structure , and find multi - soliton solutions .
suppose @xmath57 are two arbitrary complex numbers .
we consider the following lax operator : @xmath58 where @xmath59 , @xmath60 , and @xmath32 .
[ lem - trivial ] denote @xmath61 , then the following statements hold true : * there exists an operator @xmath62 where @xmath63 are differential polynomials of @xmath45 , such that @xmath64 .
* there exists an operator @xmath65 where @xmath66 are differential polynomials of @xmath45 , such that @xmath67 .
the definition of the fractional power of @xmath68 will be given in sec.[sec-2 ] .
the fractional volterra hierarchy ( fvh ) is defined by the following lax equations : @xmath69 , \label{fvh}\ ] ] where @xmath70 , @xmath71 , and the operator @xmath72 reads @xmath73 in the above definition , the positive or negative part of an operator is given by @xmath74 define the residue operation as follow @xmath75 then the main results of the present paper is the following theorem .
[ thm - main ] the fvh has the following properties : * it is integrable , that is , for any @xmath76 and @xmath77 , we have @xmath78=0.\ ] ] * it can be written as a hierarchy of hamiltonian systems @xmath79 where the hamiltonian operator @xmath80 reads @xmath81 and the hamiltonians @xmath82 are given by @xmath83 * it has a tau structure .
more presicely , define @xmath84 then for any solution @xmath85 , there exists a function @xmath86 , such that @xmath87 the dubrovin - yang conjecture for the special cubic hodge integrals can be stated as the following _ hodge - fvh correspondence_. [ main - conj ] let @xmath88 be the free energy of hodge integrals with @xmath24 given in , and @xmath89 , @xmath90 , @xmath45 be given in , .
then the recombined hodge hierarchy @xmath91 coincides with the fvh after the rescaling @xmath92 the paper is arranged as follow : in sec.[sec-2 ] we give the definition of the lax operator @xmath68 and its fractional powers . in sec.[sec-3 ] we prove the main theorem of the paper . in sec.[sec-4 ] we present the multi - soliton solutions of the fvh .
finally , in sec.[sec-5 ] we give some concluding remarks .
let @xmath93 be a commutative @xmath94-algebra with a gradation @xmath95 such that @xmath93 is topological complete with respect to the induced decreasing filtration @xmath96 an element @xmath97 can be decomposed as @xmath98 we often write it as @xmath99 where @xmath100 is just a formal parameter , whose power counts the degree .
let @xmath101 be a derivation with degree one , that is @xmath102 .
since @xmath93 is complete , the exponential map of @xmath103 is well - defined , which is called the shift operator , and is denoted by @xmath104 then , for any complex number @xmath105 , we can defined the @xmath106-th power of @xmath107 as follow : @xmath108 let @xmath109 be a complex number .
the ring of fractional pseudo - difference operators with step size @xmath110 is defined as the following @xmath93-module @xmath111 equipped with the following multiplication : @xmath112 we adopt the @xmath113-adic topology on @xmath114 , so that its elements are convergent .
we further assume that there is a suitable topology on @xmath115 such that the exponential map @xmath116 is well - defined .
then it is easy to see that @xmath117 is also well - defined , since @xmath118 where @xmath119 does exist due to the completeness of @xmath93 .
suppose @xmath120 , and @xmath121 has the following form @xmath122 the main goal of the this section is to construct the @xmath106-th power of @xmath68 for an arbitrary @xmath123 .
we consider the case with @xmath124 first . by using the integral form of the baker - campbell - hausdorff ( bch ) formula ( see e.g. @xcite ) , one can obtain the following identity : @xmath125 so the @xmath106-th power of @xmath124 can be defined as @xmath126 on the other hand , if @xmath127 its logrithm is given by @xmath128 which is convergent in the @xmath113-adic topology of @xmath114 . finally ,
if @xmath68 is given by , we can write it as @xmath129 , where @xmath130 we define @xmath131 , @xmath132 , then @xmath133 which can be obtained from the bch formula again . then the @xmath106-th power of @xmath68 is defined as @xmath134
let @xmath45 be the coordinate on @xmath94 , and @xmath115 be the @xmath94-algebra of entire functions on @xmath94 .
we define @xmath135,\ ] ] which is completed with respect to the following degree @xmath136 then @xmath93 satisfies the assumptions given in the last section .
define @xmath137 then @xmath103 is a degree - one derivation , so we can define its exponential map @xmath107 on @xmath93 , and the ring @xmath114 of fractional pseudo - difference operators with an arbitrary step size @xmath109 .
let @xmath57 be two arbitrary complex numbers , and @xmath138 , then the following operator @xmath139 is an element of @xmath140 , which is called the lax operator of the fvh . according to the definitions given in the last section
, we can define the @xmath106-th power of @xmath68 in both @xmath114 and @xmath141 for an arbitrary @xmath105 .
we denote @xmath142 then they fulfill the requirements asked in lemma [ lem - trivial ] , so this lemma is proved trivially
. then we can define @xmath143 as , and define the fvh by .
it is needed to explain that why the equation gives a partial differential equation for @xmath45 .
we take the @xmath144 case for example .
denote by @xmath145 , then there is @xmath146 such that @xmath147=[l^{\frac{\alpha+\beta}{\beta}k } , l]=0,\ ] ] so the equation can be written as @xmath148=-[b ' , l].\ ] ] let @xmath149 , then we have @xmath150 in the above equation , both of the second term and the third term are formal power series of @xmath151 .
however , the second term does nt contain negative powers of @xmath151 , while the third term does nt contain positive powers of @xmath151 , so both of them should be equal to the zeroth power of @xmath151 , so it gives a partial differential equation for @xmath45 .
the @xmath152 case is similar . according to the definitions given in the last section
, one can show that @xmath153 then it is easy to obtain the @xmath154-flow of the fvh @xmath155 similarly , we have @xmath156 so the @xmath157-flow of the fvh reads @xmath158 the local calabi - yau condition is symmetric in @xmath51 , @xmath52 , @xmath159 , so there should exist an @xmath160-action on @xmath161 . in sect.[sec-1 ] , we used the reflection @xmath162 to obtain the flow @xmath163 from the flow @xmath164 .
the other elements of @xmath160 can be also used .
for example , if we intoduce the following flows : @xmath165 and consider the action of @xmath166 or @xmath167 on @xmath161 , then one can obtain the flow @xmath168 from @xmath164 or @xmath163 : @xmath169 one can also find other flows @xmath170 by using the similar method .
however , we do not know how to represent these new flows in the lax form .
the following lemma can be easily proved by using the definition , of the fvh , so we omit its proof . for @xmath171 , @xmath172
, we have @xmath173=0.\ ] ] by using this lemma , one can proved the first part of theorem [ thm - main ] , that is , the equation indeed define an integrable system . to prove the second part of the theorem
, we need to use some identities about the variational derivatives of @xmath82 . for @xmath70 , and @xmath71
, we have @xmath174 we prove the @xmath144 case only , since the proof for the @xmath152 case is similar . recall that @xmath175 by using the following well - known identity @xmath176 one can show that @xmath177 so we have @xmath178 on the other hand , we write @xmath179 as @xmath180 then , by using the bch formula , we obtain @xmath181 so we have @xmath182 where we used the following identity : @xmath183 finally , by replacing @xmath184 by @xmath185 , the lemma is proved .
for @xmath70 , and @xmath71 , we have @xmath186 suppose in @xmath114 or @xmath141 we have @xmath187 where the summation is truncated on the positive or negative direction .
so we have @xmath188 then we use two methods to compute @xmath189 : @xmath190 it is easy to see that @xmath191 , so we have @xmath192 where @xmath193 belong to the kernel of @xmath194 , so they must be constants . finally , by taking @xmath195 , one can show that @xmath196 . the lemma is proved . by using the above two identities
, we have @xmath197{\lambda}_1=\left(1-{\lambda}_1^{-1}\right)\operatorname{\mathrm{res}}a_i^k\\ = & \left(1-{\lambda}_1^{-1}\right)\frac{{\lambda}_3 - 1}{{\lambda}_2 - 1}\operatorname{\mathrm{res}}\left(e^u { \lambda}_1^{-1}a_i^k l^{-1}\right)=p\left(\frac{\delta h_{i , k}}{\delta u}\right).\end{aligned}\ ] ] the operator @xmath80 is obviously a hamiltonian operator , so the second part of theorem [ thm - main ] is proved . to prove the third part of theorem [ thm - main ] , we first derive some identities that are satisfied by the functions @xmath198 in the following lemma . for @xmath171 , @xmath199 , we have @xmath200 we only prove the @xmath144 case , since the @xmath152 case is similar .
the first identity can be easily proved by using the definition , of the fvh . to prove the second one , we first represent @xmath201 and @xmath202 in the forms
@xmath203 then we have @xmath204\\ = & \operatorname{\mathrm{res}}\left[\sum_{m=0}^k \operatorname{\mathrm{res}}\left(a_i^k { \lambda}_3^{-m}\right){\lambda}_3^m , \sum_{n\in{\mathbb{z } } } \operatorname{\mathrm{res}}\left(a_j^l { \lambda}_3^{-n}\right){\lambda}_3^n\right]\\ = & \sum_{m=1}^k\left(\operatorname{\mathrm{res}}\left(a_i^k { \lambda}_3^{-m}\right){\lambda}_3^m\left(\operatorname{\mathrm{res}}\left(a_j^l { \lambda}_3^{m}\right)\right)\right.\\ & \qquad\qquad \left.-\operatorname{\mathrm{res}}\left(a_j^l { \lambda}_3^{m}\right){\lambda}_3^{-m}\left(\operatorname{\mathrm{res}}\left(a_i^k { \lambda}_3^{-m}\right)\right)\right)\\ = & \sum_{m=1}^k\left({\lambda}_3^m-1\right)\left(\operatorname{\mathrm{res}}\left({\lambda}_3^{-m}a_i^k\right)\operatorname{\mathrm{res}}\left(a_j^l { \lambda}_3^{m}\right)\right)\\ = & \left({\lambda}_3 - 1\right)\omega_{i , k ; j , l}.\end{aligned}\ ] ] the lemma is proved .
[ lem - iden ] the differential polynomials @xmath198 satisfy the following identities : @xmath205 where @xmath206 , @xmath207 .
the above lemma implies that @xmath208 so there are constants @xmath209 and @xmath210 such that @xmath211 note that the terms on the left hand side of have positive degrees , so we have @xmath212 . to find @xmath209 ,
let us take @xmath195 and @xmath213 , then the binomial series gives @xmath214 so we have @xmath215 which imply @xmath216 . a proof of these identities and their generalization can be found in @xcite .
the lemma is proved .
finally , to prove the last part of theorem [ thm - main ] , we only need to verify the compatibility of the equations - , which has been proved in the above two lemmas .
so theorem [ thm - main ] is now proved .
the lax equations of the fvh are the compatibility conditions of the following linear systems : @xmath217 in this section , we are to apply darboux transformation method @xcite to these linear systems in order to obtain special solutions , in particular soliton solutions , of the fvh .
suppose @xmath85 is a solution of the fvh , and @xmath218 is an eigenvalue of the corresponding lax operator @xmath68 , then one can find a solution @xmath219 of the above lax pair , which is called a wave function for the potential @xmath45 and the eigenvalue @xmath218 .
suppose @xmath220 is a wave function for the potential @xmath45 and the eigenvalue @xmath218 .
define operators @xmath221 then @xmath222 has the form @xmath223 , where @xmath224 moreover , @xmath225 is also a solution of the fvh .
it is easy to verify the expression .
to prove that @xmath225 is also a solution of the fvh , one need to show @xmath226,\ ] ] which is implied by the equation @xmath227 here @xmath228 is the operator with @xmath68 replaced by @xmath222 .
we take the @xmath144 case for example .
then @xmath229 it is easy to see that @xmath230 so the equation also can be written as @xmath231 by using the following expression of the operator @xmath232 ( in @xmath114 ) : @xmath233 one can show that @xmath234 which implies immediately .
the lemma is proved . by applying the darboux transformation @xmath4 times
, we obtain the following theorem . its proof is standard @xcite , so we omit it here .
suppose @xmath45 is a solution of the fvh , and @xmath235 are the wave functions for the eigenvalues @xmath236 of @xmath68 .
define operators @xmath237 where @xmath238 then @xmath222 has the form @xmath223 , where @xmath239 moreover , @xmath225 is also a solution of the fvh .
it is easy to see that the function @xmath240 is a trivial solution of fvh .
starting from this solution , we can obtain the @xmath4-soliton solutions of fvh by using the above theorem .
denote by @xmath241 , and assume that @xmath242 is an eigenvalue of @xmath243 .
suppose @xmath244 is a root of the equation @xmath245 , then it is easy to see that the function @xmath246 where @xmath247 is a wave function for the eigenvalue @xmath218 .
we assume @xmath248 are two positive real numbers from now on , and @xmath218 is a real number such that @xmath249 then the equation @xmath245 always has two real roots @xmath250 and @xmath251 , such that @xmath252 in this case , the general real wave function has the following form : @xmath253 where @xmath254 are arbitrary real numbers . to construct the @xmath4-soliton solution ,
let us take @xmath255 satisfying the condition , and denote @xmath256 where @xmath257 are some real numbers . then we have the @xmath4-soliton solution @xmath258 where @xmath259 is given by .
this expression also shows that @xmath259 is the tau function for the solution @xmath45 .
note that not all choices of @xmath260 lead to a positive @xmath259 .
it is an interesting problem to find the condition such that @xmath261 for all @xmath262 .
take @xmath263 , @xmath264 , @xmath265 and @xmath266 for @xmath70 , @xmath267 .
then the function @xmath268 gives a @xmath269-soliton solution for the @xmath154-flow of the fvh , see figure [ fig-1]-[fig-4 ] .
, scaledwidth=80.0% ] , scaledwidth=80.0% ] 1em , scaledwidth=80.0% ] , scaledwidth=80.0% ]
the fractional volterra hierarchy that we constructed in this paper is a generalization of the usual volterra lattice hierarchy .
we can also view this hierarchy as a certain reduction of the 2d toda lattice hierarchy @xcite .
indeed , the operators @xmath270 introduced in lemma [ lem - trivial ] satisfy the following equations : @xmath271,\quad { \varepsilon}\frac{{\partial}a_i}{{\partial}t^{2,k}}=-\left[\left(a_2^k\right)_- , a_i\right],\ ] ] so the fvh is actually a reduction of the 2d toda lattice hierarchy with the shift operator @xmath272 .
the reduction condition is given by @xmath273 where @xmath274 , @xmath275 are two nonzero complex numbers .
furthermore , one can consider the following more general reduction condition : @xmath276 where @xmath277 is a positive integer .
this condition will lead to a fractional generalization of the bigraded toda lattice hierarchy @xcite .
1em * acknowledgement * we are grateful to boris dubrovin and di yang for sharing with us their discovery of the relation of special cubic hodge integrals with the equation and for helpful discussions .
we would also like to thank fedor petrov and vladimir dotsenko for their proof of the four identities given in the end of sect.[sec-3 ] .
this work is supported by nsfc no .
11371214 and no.11471182 . | the generating function of cubic hodge integrals satisfying the local calabi - yau condition is conjectured to be a tau function of a new integrable system which can be regarded as a fractional generalization of the volterra lattice hierarchy , so we name it the _ fractional volterra hierarchy_. in this paper , we give the definition of this integrable hierarchy in terms of lax pair and hamiltonian formalisms , construct its tau functions , and present its multi - soliton solutions . |
chronic kidney disease ( ckd ) , which prevalence is still growing worldwide , confers a higher risk of coronary artery disease ( cad ) , chronic heart failure ( chf ) and/or death independently of conventional cardiovascular risk factors ( 1 , 2 ) . tens of millions of persons worldwide have combined cardiovascular disease ( cvd ) and ckd ( 3 ) . the risk of cvd in patients with chronic renal disease appears to be far greater than in the general population ( 4 ) .
the incidence of cardiac morbidity and mortality is high in patients treated with hemodialysis ( hd ) ( 5 ) .
cardiovascular disease is the principal cause of mortality in patients with renal failure and left ventricular ( lv ) abnormalities that are adverse prognostic indicators for cardiovascular outcome ( 6 ) .
hd - induced myocardial stunning driven by ischemia is a recognized complication of hd , which can be ameliorated by hd techniques that improve hemodynamic ( 7 ) .
end - stage renal disease ( esrd ) associates with numerous changes in cardiac structure and function that may account for the sustained high prevalence of morbidity and mortality from cardiovascular disease , particularly ischaemic heart disease and heart failure ( 8) . the aim of this study was to evaluate the relationship between hd and the echocardiographic findings in patients with advanced renal failure in the west of iran .
in an analytical and cross - sectional study between 2012 and 2014 that was approved by the ethics committee of kermanshah university of medical sciences , 150 patients with chronic kidney disease ( ckd ) ( disease signs were confirmed for them clinically ) referred to emam reza hospital , kermanshah , iran .
we checked the general characteristics such as age , sex , hypertension and diabetes in the patients .
the echocardiographic information was checked in all patients before the first hd and after one year .
measurement method for ejection fraction was e balling and for diastolic function was tissue doppler .
anemia , thyroid conditions and hd through an arteriovenous fistula or permanent catheter of hd for the patients are not considered .
inclusion criteria : advanced kidney disease , having of complete echocardiographic information and the similarity of effects on echocardiographic findings , such as drugs of inotrope .
exclusion criteria : having of incomplete echocardiographic information , effective treatment measures , such as cabg and valve repair . for analyzing of data , was used spss version 20 software ( spss , inc . , chicago , usa ) .
the t - test was done for means and chi - square test for other values .
the mean age at diagnosis for the patients was 57.8 years ( range , 12 to 86 year ) , 79 patients ( 52.7% ) were males ( table 1 ) .
out of 150 patients , 112 patients ( 74.7% ) had diabetes and 117 patients ( 78% ) had a history of hypertension .
the characteristics of patients ( n=150 ) there were significant differences between before the first hd and after one year for all the echocardiographic findings in table 2 .
prevalence of the echocardiographic findings was more after the first hd compared with before the first hd in all patients ( p<0.05 ) .
the echocardiographic findings of the patients , before and after the first hemodialysis ( n=150 ) table 3 shows the echocardiographic findings for 112 diabetic patients , before the first hd and after one year .
prevalence of the echocardiographic findings was more after the first hd compared with before the first hd in diabetic patients ( p<0.05 ) .
the echocardiographic findings of diabetic patients , before and after the first hemodialysis ( n=112 ) table 4 shows the echocardiographic findings for 38 non - diabetic patients , before the first hd and after one year .
the prevalence of the echocardiographic findings was more after the first hd compared with before the first hd in non - diabetic patients ( p<0.05 ) , exception for the tricuspid valve stenosis , impaired right ventricular volume , systolic dysfunction and pulmonary hypertension that had no significant differences before and after the first hd ( p>0.05 ) .
the echocardiographic findings of non - diabetic patients , before and after the first hemodialysis ( n=38 )
in this study , we checked the relationship between hd ( before the first dialysis compared with after one year ) and the echocardiographic findings in patients with ckd .
in addition , we divided the patients into two groups ( diabetic and non - diabetic patients ) and then compared the echocardiographic findings before the first dialysis compared with after one year
a lot of cross - sectional studies in dialysis patients reported that traditional cvd risk factors such as hypertension and hypercholesterolemia had low predictive power , while markers of inflammation and malnutrition were highly correlated with cardiovascular mortality ( 9 ) . on the other hand ,
patients with ckd have increased risks of accelerated atherosclerosis , nonfatal myocardial infarction , congestive heart failure , atrial and ventricular arrhythmias , and cardiac death and also present difficult scenarios in using conventional cardioprotective therapy ( 3 ) .
ckd accelerates the course of coronary artery disease , independent of conventional cardiac risk factors ( 10 ) .
vascular calcification ( vc ) is highly prevalent and rapidly progressive in high stage ckd ( 11 ) . in ckd patients ,
lv diastolic dysfunction occurs frequently and is associated with heart failure ( hf ) and higher mortality ( 12 ) .
the former causes concentric lv hypertrophy , results of hypertension and aortic stenosis , and is also associated with diabetes mellitus and anemia .
the clinical consequences of cardiomyopathy include heart failure , ischaemic heart disease , dialysis hypotension , and arrhythmias . the adverse impact of ischaemic heart disease is probably mediated through the development of cardiac failure ( 13 ) .
the results indicate that lv diastolic dysfunction as revealed by the increased peak velocity of atrial filling reflects arterial stiffening in type 2 diabetic ( t2d ) patients .
in addition , myocardial wall thickening at the lv outflow tract reflects not only arterial stiffening but also carotid atherosclerosis . therefore , these abnormal echocardiographic findings of lv diastolic dysfunction and myocardial wall thickening may be useful markers of the presence of progressive arteriosclerosis in t2d patients ( 14 ) .
one study ( 11 ) , showed for the first time that microcirculatory dysfunction is specifically associated with a vc .
furthermore , both vc and microcirculatory dysfunction are associated with atherosclerosis , arterial stiffness , autonomic dysfunction and lv hypertrophy as well as all cause and cardiovascular mortality ( 11 , 15 , 16 ) .
it has been reported that ischemia maintained for several hours by subtotal coronary occlusion can also cause lv dysfunction that persists for days after the release of the occlusion and restoration of myocardial blood flow .
stunning has also been demonstrated in conscious dogs with subtotal coronary obstruction in which ischemia was induced by muscular exercise ( 17 ) .
hd - induced myocardial stunning is common , and may contribute to the development of heart failure and increased mortality in hd patients .
after 12 months , both groups of patients ( with and without evidence of hd - induced regional wall motion abnormalities ) exhibited a significant deterioration in sbp during hd .
conventional hd exerts a significant acute cardiovascular stress , the exact consequences of which are poorly understood .
this study supports the contention that subclinical myocardial ischemia is commonly precipitated by dialysis ( 18 ) .
the absence of sinus rhythm was an important risk indicator for all - cause death and cardiovascular events in patients with t2d on hd .
lv hypertrophy was predictive of stroke and sudden death ( 19 ) . compared with non - diabetics ,
diabetics had a 48% significant increase in the primary endpoint , a 56% significant increase in cardiovascular death , a 30% significant increase in myocardial infarction , a 39% significant increase in stroke , and a 206% significant increase in hospitalization for congestive heart failure ( 20 ) . in our study
, there was no significant different between before and after the first dialysis in non - diabetic patients compared with diabetic patients in some of cvd factors .
also , according to the findings of this study , seems that more accurate selection of patients for dialysis , paying special attention to hemodynamic change during dialysis , patient education about diet and better control of uremia and diabetes is essential . | background : the incidence of cardiac morbidity and mortality is high in patients treated with hemodialysis ( hd ) . the aim of this study was to evaluate the relationship between hd and the echocardiographic findings in patients with chronic kidney disease ( ckd).methods : between 2012 and 2014 , 150 patients with ckd .
the echocardiographic data were done based on american society of cardiology ( ase ) .
measurement method for ejection fraction was e balling and for diastolic function was tissue doppler .
anemia , thyroid conditions and dialysis through an arteriovenous fistula or permanent catheter of dialysis for the patients are not considered.results:the mean age at diagnosis for the patients was 57.8 years , 52.7% were males .
out of 150 patients , 112 patients ( 74.7% ) had diabetes and 117 patients ( 78% ) had a history of hypertension .
the prevalence of all echocardiographic findings was more after the first dialysis compared with before the first dialysis in diabetic patients ( p<0.05 ) , but in non - diabetic patients , was not for the tricuspid valve stenosis , impaired right ventricular volume , systolic dysfunction and pulmonary hypertension ( p>0.05).conclusions : according to the findings of this study , seems that more accurate selection of patients for dialysis , paying special attention to hemodynamic change during dialysis , patient education about diet and better control of uremia and diabetes is essential . |
alzheimer 's disease ( ad ) is the leading cause of dementia in older adults .
currently 4.5 million americans have ad and this number is expected to rise to 13.2 million by the year 2050 .
estimates within canada suggest that over half a million individuals over 65 years of age have ad or a related disease [ 2 , 3 ] .
while memory problems are the most characteristic symptom of this disorder , many individuals also experience progressive problems with communication [ 46 ] .
the objective of this paper was to systematically review the effectiveness of methods to improve communication between individuals with ad and their formal and informal caregivers .
the decline of communication abilities in ad is gradual and is characterized primarily by problems with object naming [ 79 ] , coherence , and discourse production including the use of fewer information units , fewer target propositions , and an increased proportion of pronoun use .
language comprehension also worsens gradually , although phonological and syntactic skills remain preserved until the advanced stages of the disease [ 14 , 15 ] .
the deterioration of the individual 's ability to communicate contributes considerably to the stress and burden of caregivers [ 1618 ] and is often classified among the most serious stressors that caregivers must face [ 19 , 20 ] .
poor communication between the caregiver and the care recipient can lead to conflicts , isolation or depression in one or both of these individuals [ 18 , 21 , 22 ] and may lead to earlier placement in institutions [ 1618 , 23 ] .
adoption of practices to enhance the verbal communication of individuals with ad could help mitigate these problems . knowing which practices are effective
would therefore be of interest to nursing and rehabilitative staff , as well as family members .
different methods have been proposed to maximize the potential of caregiver - patient communication and include memory aids , education and training of caregivers , and activity programs .
memory aids generally consist of biographical information ( e.g. , name , address , telephone number , etc . ) , photos of family members , and descriptions of important events in the life of the individual . by using images and phrases that are brief and simple ,
memory aids seek to capitalize on patients ' automatic communication abilities , with the goal of improving the structure and quality of communication with others . at the linguistic level ,
memory aids provide semantic support in the form of sentences , words and images , and access to other semantic information stored in long - term memory .
moreover , the provided written support can be used to compensate for certain comprehension deficits that may appear when instructions are provided verbally . by offering visual cues , memory aids can also serve to remind individuals of the current task or topic of conversation , thus enabling them to better participate in the communicative interaction .
these cues also limit the number of choices that must be made and provide concrete topics for conversation .
socially , memory aids support the desire to communicate , another aspect of communication that often remains intact in individuals with dementia .
caregiver communication enhancement education and training techniques constitute another group of methods used to improve communication between caregivers and care recipients .
focused is a systematic program with the goals of providing caregivers with information pertaining to ad and communication , correcting any misinformation pertaining to communicating with individuals diagnosed with this disease , and offering techniques aimed at maximizing communication potential .
diverse strategies are recommended such as using close - ended or choice - based questions rather than open - ended ones , using direct and simple phrases , repeating key words and ideas in the conversation , noting a change in the topic of conversation , using direct contact ( e.g. , touch , eye contact ) , as well as utilizing comments and nonverbal cues to preserve the quality and flow of the conversation .
other similar programs incorporate a variety of additional strategies including : offering positive feedback when individuals with dementia follow through on requests , giving the individuals sufficient time to answer a request or a question , and speaking with the individuals about their life and pastimes .
feedback to caregivers related to their use of specific versus general instructions , one - step instructions , and positive comments to the person with dementia is also recommended .
in addition , there are programs to teach caregivers tailor - made strategies to improve communication on the part of a particular person with ad .
this individualized approach assists the caregiver to identify effective and noneffective conversation techniques and to use participants ' strengths to improve their interactions .
aspects of conversation that can be analyzed include turn - taking during a communicative interaction , topic maintenance , and resolving communication breakdowns .
the caregiver communication enhancement education and training program uses a similar approach .
as well , there are a number of activity - based approaches to increasing communication .
these interventions may be carried out individually or in groups and use very specific ( e.g. , preparing a meal ) or diverse activities to stimulate communication .
generally , the focus of these groups is on improving or maintaining a number of functional skills , with communication being one . to date ,
there have been two systematic reviews of interventions to improve the communication of persons with ad with caregivers . in the first ,
the focus was solely on strategies used by formal health care workers ; the effectiveness of interventions with family and other informal care givers was not included in this review .
the purpose of this project was to conduct a review with the goal of identifying , based on empirical evidence , the most effective ways for enhancing the verbal communication of an individual with ad with his or her formal or informal caregiver .
this outcome was chosen as the focus because it was felt to be the best measure of success in optimizing communication between these two partners .
it was anticipated that the literature would contain only a limited number of randomized controlled trials ( rcts ) investigating the efficacy of methods used to improve communication between individuals with ad and their caregivers .
therefore , it was decided that all relevant studies , regardless of the experimental method used , would be included in this review .
the following inclusion criteria were adopted : ( i ) the study must be experimentally - based ; ( ii ) the results must be quantitative in nature ; ( iii ) the intervention examined by the study must be specifically designed to improve verbal communication between the individuals with dementia and their caregivers ; ( iv ) at least 50% of the individuals sampled must have a confirmed diagnosis of ad .
where the specific dementia diagnosis of the participants was not provided , the studies were included if the majority of the participants were women , since ad is the most common dementia diagnosis among women .
the two exclusion criteria were that : ( 1 ) the study was published in a language other than english or french ; and ( 2 ) communication outcome measures were directed exclusively at the caregiver ( i.e. , there was no information on the effect of the intervention on the verbal communication of the individual with dementia ) .
a literature search was conducted up to july 2006 and then updated in june 2009 using the following computerized databases : psychinfo ( starting from 1872 ) , cinahl ( starting from 1982 ) , embase ( starting from 1980 ) , medline ( starting from 1966 ) , rehabdata , and comdis .
search terms were identified by a research librarian ( search terms available on request ) .
as well , we consulted a database of articles relevant to communicating with individuals diagnosed with dementia that had been compiled by kerry byrne under the supervision of her doctoral advisor , j.b .
first , all of the titles of articles produced by the literature search were read by two reviewers ( two of the authors ) who judged whether the study was likely to meet the inclusion criteria .
next , for all those judged as potential candidates by either reviewer , abstracts were obtained and read .
subsequently , the actual articles were obtained if both reviewers felt that the abstract indicated that the study was likely to meet the inclusion criteria . in cases where there was disagreement , a third individual ( another author )
was consulted to cast the deciding vote . following retrieval of the articles , the two reviewers performed a detailed analysis of each study .
a third author calculated effect sizes ( cohen 's d ) and p - values where possible .
finally , based on these results , a summary recommendation was made concerning communication interventions with individuals with ad using the strength of recommendation taxonomy ( sort ) criteria . using these criteria , systematic reviews or high - quality rcts provide level a evidence . according to the sort guidelines a
high - quality rct is defined as including concealed allocation , blinding if possible , intention - to - treat analysis , adequate statistical power , and adequate followup ( at least 80% ) .
this allows for rcts to be considered high quality even when patients can not be masked to treatment allocation , a criterion that can be difficult to meet in many communication studies .
other types of studies provide level b evidence , as they may be open to threats to internal validity such as observer bias , allocation bias , placebo or hawthorn affect , or lack of control for co - occurring treatments or maturation .
titles and abstracts of 2000 articles were identified in the electronic searches ( 1296 from the original search and 704 from the updated search ) .
sixty - seven papers were identified as potentially appropriate to the review and were obtained and assessed .
fifty - three were excluded from the review ( table 1 ) . among studies with experimental methods ,
the most common reasons for exclusion were noninclusion of measures of communication for the affected individual during conversation with caregivers and intervention not directed at enhancing the affected individual 's communication .
in six of the included studies , the care recipients had an unspecified diagnosis of dementia .
the inclusion criteria previously described in the methodology were applied , but certain cases remained problematic . in the case of allen - burge et al .
no information was given on whether questionable might be akin to possible dementia , the more standard way of stating that some , but not all , of the criteria for diagnosis are met .
however , given that the mmse scores of participants were consistent with a diagnosis of dementia , the study was included .
burgio et al . posed a similar problem in that only 52.9% of the sampled experimental group had a diagnosis of dementia . again , since the participants ' mmse scores appeared uniformly very low , we decided to include this study in the review .
of the 13 studies included in the review , eight examined the effects of memory books , three evaluated training programs , and two reported on the outcomes of activity programs .
the setting , participants , interventions , and designs of these studies are summarized in table 2 . the results of each of the included studies are displayed in table 3 .
neither met the sort criteria for a high quality rct . of designs used in the six remaining studies ,
4 were single subject multiple baseline bourgeois 1990 , bourgeois 1992 , bourgeois 1996 , hoerster 2001 , one was a pretest - posttest study allen - burge 2001 and one was a case study spilkin 2003 .
the results of one of the rcts examining the impact of memory aids and caregiver training on participants ' communication with formal caregivers indicated that , following this intervention , participants produced significantly more utterances and more informative communications during 5-minute conversations with their formal caregivers . due to the reporting methods used in the other rct that examined memory aids and staff training burgio 2001 , effect sizes for these outcomes could not be calculated .
the authors noted no significant effect for group x time differences in coherent verbal interactions with formal caregivers .
the pretest - posttest study of memory aids and staff training indicated that the percentage of time in coherent speech , percentage of time talking with others , and the number of positive statements to formal caregivers per hour all increased following intervention , but that these effects returned to pretest levels at one - month followup .
two of the multiple baseline single - subject studies demonstrated improvement in on - topic statements to informal caregivers following the use of memory books and caregiver training for most of the participants [ 27 , 90 ] .
an additional multiple baseline single - subject study demonstrated possible improvement in on - topic statements to formal caregivers but the results were difficult to interpret due to the lack of a stable baseline .
the one case study of memory aids demonstrated increased maximal turns and improved topic maintenance with formal caregivers following intervention .
social validation for this intervention was provided by most caregivers noting improved participant communication in all but one study . using the sort criteria ,
given the above results , the use of memory aids with caregiver training would be recommended for use by clinicians with a rating strength of b. this rating is supported by results from two rcts from which there were mixed results .
there were three studies that examined different education and training programs for the communication partner .
one , a lower - quality rct , assessed a family visit training program mccallion 1999 .
a second pretest - posttest study examined affected individuals ' responses to direct or indirect listener repair responses gentry 2007 .
no clinically or statistically significant changes in communication were noted in the lower - quality rct of family visiting intervention program mccallion 1999 .
the pretest - posttest study of individualized communication prescriptions demonstrated a significant change in number of words per topic , but not number of total words acton 2007 . in the pretest - posttest study of indirect versus direct communication repair , all three participants demonstrated less topic changes under the indirect repair gentry 2007 . due to the small number of participants , the significance of these findings could not be tested . within these studies
there was no firm support for intensive caregiver training , with the exception of individualized communication prescriptions .
overall , the strength of recommendation for this intervention was c , a result supported by one rct .
one , a high - quality rct , examined the effects of a walking and talking intervention cott 2002 . the other , a nonrandomized controlled trial , examined the effects of a breakfast club group pietro 1998 .
in the only high - quality rct included in this review , cott and her colleagues examined the effects of a program in which pairs of residents were encouraged to talk with one another , either while sitting or while walking .
neither condition led to better communication outcomes and both , in fact , demonstrated a tendency to worsened outcomes . using a nonrandomized controlled trial ,
pietro and boczko demonstrated the effectiveness of a daily group intervention that focused on communication stimulated by the preparation and sharing of breakfast . using the sort criteria , straight conversational or walking and talking programs
would not be recommended , but a breakfast - based activity group would receive a recommendation with a rating strength of b. this rating is not supported by results from an rct .
prior to discussing some generalities regarding ways of improving communicative interactions between individuals with ad and their caregivers gleaned from this , it is important first to note some important observations from our search results .
first , almost one - third of the excluded papers reported the results of interventions to enhance communication between individuals with alzheimer 's disease and their communication partners but did not include a quantitative change in the verbal communication of the affected individual with a conversational partner .
rather , these studies used language measures that do not capture communicative interaction ( e.g. , naming ) , or measured aspects of caregiver communication or knowledge of recommendations . in order to convincingly demonstrate the effectiveness of interventions in improving the communication of individuals with alzheimer 's disease , future studies must include measures that reflect the communication abilities of the affected individual .
as well , among the studies that met the criterion of having a communication outcome , there were only four randomized control trials addressing this issue , and three were considered lower quality .
it must be acknowledged that it is often difficult to conduct an rct within the field of communication disorders and , as such case - studies and single - subject designs have traditionally been used .
however , due to their ability to better control threats to internal validity , rcts are regarded as the gold standard in determining the clinical efficacy of an intervention . to this end , it is suggested that future studies investigating the efficacy of recommended techniques to improve communication of persons with ad follow the rct protocol when possible , including those criteria necessary to be considered a high - quality rct ( particularly masking of evaluators ) . in light of the above , and the fact that there were only a few studies meeting the inclusion criteria for selection , the majority of which had compromised internal validity due to methodological limitations , one must be cautious about generalizing the results of this review to clinical practice .
nonetheless , bearing in mind these methodological limitations ( including weak estimates , small sample sizes , absence of control groups , nonrandom group allocation , and few instances of blinding of evaluators ) , trends in performances did emerge allowing us to suggest the following recommendations .
memory aids demonstrated the clearest effectiveness in improving patients ' discourse related to the particular topics that were linked to the memory - aids .
these tools appear to be effective in enhancing topic maintenance , as evidenced in improvement in time on topic , words per topic , and fewer topic changes .
this suggests that these interventions are addressing verbal attention and helping individuals focus their thoughts .
as well , participants ' performance decreased over time where followup training was not provided .
this latter finding underscores the importance of continuing training for communication partners using these tools .
memory aids have received only limited testing with family caregivers ( e.g. , spouses ) . on the one hand , memory aids and training may be more or less effective when used by family caregivers compared to formal caregivers .
family caregivers may already be familiar with the content of memory books ( e.g. , family members , pets , previous occupation ) and therefore able to initiate related conversation without them .
on the other hand , memory books may cue the family caregiver to converse on specific topics , and these conversations may benefit from the in - depth shared knowledge of these topics . further research on this intervention with family caregivers is recommended .
the family visit intervention program could not be considered an effective intervention given the research available to date .
only two studies of activity - based programs that included evaluation of communication outcomes were identified in our search .
the breakfast club intervention demonstrated promising results in a nonrandomized trial ; a high - quality trial of this intervention is warranted .
lack of an effect of walking and talking in a high - quality rct is likely due to the divided attention demands of the combined tasks .
lack of effect of the conversation - based intervention in this study seems to indicate that increasing the opportunity to converse without other support or stimulation , such as that provided by a shared activity , may not enhance communication .
our results build on those of zientz et al . by demonstrating level b evidence for the effectiveness of memory aids with caregiver training .
they also build on mcgilton et al . by extending the search beyond formal caregivers in institutional settings .
this systematic review was carried out using recommended methods including a search strategy designed by a research librarian , and selection of studies and extraction of data by two independent reviewers .
one important limitation of the review was that effect sizes could not be calculated for all outcomes due to the data presentation limitations within the original studies .
opening the inclusion criteria to allow for studies using a wide variety of experimental designs ( i.e. , not just rcts ) allowed us to consider the findings of a greater number of studies .
however , conclusions from studies with different levels of validity may be misleading . to counteract this possibility
this systematic review of the efficacy of techniques used to improve communication between individuals with ad and their caregivers indicated the highest level of support for the use of memory aids combined with caregiver training .
future high - quality studies of these interventions , incorporating measures of communicative interaction and measures of topic maintenance , are recommended . | alzheimer 's disease is the leading cause of dementia in older adults .
although memory problems are the most characteristic symptom of this disorder , many individuals also experience progressive problems with communication .
this systematic review investigates the effectiveness of methods to improve the verbal communication of individuals with alzheimer 's disease with their caregivers .
the following databases were reviewed : psychinfo , cinahl , embase , medline , rehabdata , and comdis .
the inclusion criteria were : ( i ) experimentally based studies , ( ii ) quantitative results , ( iii ) intervention aimed at improving verbal communication of the affected individual with a caregiver , and ( iv ) at least 50% of the sample having a confirmed diagnosis of alzheimer 's disease .
a total of 13 studies met all of the inclusion criteria .
one technique emerged as potentially effective : the use of memory aids combined with specific caregiver training programs . the strength of this evidence was restricted by methodological limitations of the studies .
both adoption of and further research on these interventions are recommended . |
After being driven off the stage Saturday afternoon, Democratic presidential candidate Bernie Sanders addressed the issue later before a large crowd at the University of Washington.
Set to speak at a Seattle park during the afternoon, Sanders was interrupted by activists from Black Lives Matter, who demanded the opportunity to address the crowd about police brutality against African-Americans. Sanders’ campaign allowed the activists to speak — they also sought 4 1/2 minutes of silence. When Sanders, amid some commotion and confusion, subsequently tried to regain the microphone, he was unable to do so.
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At that point, Sanders waved to the crowd and left the stage, greeting some of those who had come to hear him. Some of the crowd, which was attending an event called “Social Security Works,” was audibly restless as the protesters spoke, with some people chanting: “Let Bernie speak.” As he exited through the crowd, he urged people to come hear him in the evening.
Speaking Saturday night before an estimated 12,000 people at the University of Washington’s basketball arena, the Vermont senator addressed some of the issues behind the afternoon confrontation.
“No president will fight harder to end institutional racism and reform criminal justice system,” he said, according to The Associated Press. “Too many lives have been destroyed by [the] war on drugs, by incarceration; we need to educate people. We need to put people to work.”
Sanders also issued a statement on his website about the Black Lives Matter controversy.
“I am disappointed that two people disrupted a rally attended by thousands at which I was invited to speak about fighting to protect Social Security and Medicare. I was especially disappointed because on criminal justice reform and the need to fight racism there is no other candidate for president who will fight harder than me,” he said.
During the afternoon incident at Westlake Park, one of the protesters told the crowd: “I was going to tell Bernie how racist this city is — with all of its progressives — but you’ve already done that for me.”
The Hill.com said the speaker identified herself as Marissa Johnson, though she is known on Facebook as Marissa Jenae. A second protester was identified as Mara Jacqueline Willaford.
Black Lives Matter Seattle explained their actions in a news release: “The problem with Sanders, and with white Seattle progressives in general, is that they are utterly and totally useless (when not outright harmful) in terms of the fight for Black lives. While we are drowning in their liberal rhetoric, we have yet to see them support Black grassroots movements or take on any measure of risk and responsibility for ending the tyranny of white supremacy.”
The requested 4 1/2 minutes of silence were meant to mark the 4 1/2 hours that Michael Brown’s body remained exposed on the street after he was shot to death by police officer Darren Wilson in Ferugson, Missouri. That fatal shooting occurred one year ago, and the anniversary was marked by protesters in Ferguson; on Sunday night, a protester was shot by police there after allegedly firing upon the officers.
Protest leaders have argued that Sanders is dismissive of their concerns, falling back on his status as the most liberal candidate in the Democratic field — and his history of civil rights activism in the 1960s — as shields against criticism on racial issues.
On July 18 at a Netroots Nation gathering in Phoenix, Black Lives Matter activists disrupted an interview with Sanders and another Democratic candidate, former Maryland Gov. Martin O’Malley.
“During the action, you saw Bernie Sanders trying to talk us down, trying to speak over us,” said Angela Peoples, one of the organizers of the protest at Netroots at that time. “Basically it was as if he was trying to pretend that there weren’t 15 people in the room screaming ‘black lives matter.’”
Sanders supporters, on the other hand, complain that the activists are undermining the one candidate most likely to adopt policies that would improve the plight of many African-Americans.
Sanders’ speech Saturday night at the Hec Edmundson Pavilion also discussed the issues that have been the staple of his campaign, including economic inequality. According to the Seattle Post-Intelligencer, this line drew the biggest ovation of the night: “No person should work 40 hours a week for poverty wages.”
The candidate drew an even bigger crowd Sunday night in Portland, Oregon, speaking at the home of the NBA’s Trail Blazers to an estimated 19,000 people inside, with thousands more listening on loudspeakers outside. Notably, he was preceded by Symone Sanders, an African-American who was recently hired by his campaign to be his press secretary. She urged the crowd to chant, “We stand together,” should Sanders’ speech be interrupted by protesters. ||||| Black Lives Matter protesters prevented the Democratic presidential candidate from speaking Saturday afternoon at Westlake.
A Seattle speech by Democratic presidential candidate Bernie Sanders was pre-empted in a chaotic confrontation Saturday afternoon with a pair of Black Lives Matter protesters, who took the stage and refused to let him speak.
The Vermont senator, who has drawn huge crowds around the country, was to be the star attraction and final speaker for a rally at Westlake Park to celebrate the 80th birthday of Social Security and the success of other anti-poverty programs.
But his afternoon plans were scuttled by protesters determined to turn attention instead to Sunday’s anniversary of the shooting by a white police officer of Michael Brown, an unarmed black man in Ferguson, Mo.
Latest: Sanders vows anti-racism fight at L.A. event
It wasn’t the first disruptive tactic for activist who hijacked Sanders rally
Later in the evening, Sanders received the reception he’d expected from the Seattle area as the progressive alternative to Democratic presidential front-runner Hillary Rodham Clinton.
An estimated 15,000 supporters packed Hec Edmundson Pavilion and an overflow area as Sanders took the stage to thunderous applause and delivered an hourlong populist stemwinder about his plans to wrest the country from the control of billionaires.
As the crowd stomped and cheered, Sanders pledged to fight for a full menu of progressive policies, including 12 weeks of paid leave for new parents, a federal minimum wage of $15 an hour, and an end to unequal pay for women.
“This is not utopian dreaming,” Sanders said. “This is the country we can create if we are prepared to stand together.”
At Westlake, Sanders was just starting to address the crowd, thanking Seattle for being “one of the most progressive cities in the United States of America.”
That’s as far as he got before two women walked onstage and grabbed the microphone.
“If you do not listen … your event will be shut down,” one of the protesters told organizers, who offered to let them speak after Sanders. After a back and forth with the screaming protesters, organizers relented and said the demonstrators could go first.
Some in the largely white audience booed and chanted for protesters to let the senator talk. A few yelled for police to make arrests.
Marissa Johnson, one of the protesters, shot back, “I was going to tell Bernie how racist this city is, filled with its progressives, but you did it for me,” accusing the audience of “white supremacist liberalism.” She cited Seattle’s own police problems, including an ongoing Justice Department consent decree over use of force.
The activists demanded 4½ minutes of silence in memory of Brown, to symbolize the 4½ hours his body lay on a Ferguson street. While rally organizers raised their hands in support, some in the crowd yelled profanities.
After the few minutes of silence, the protesters said they wanted to confront Sanders for failing to address their concerns when he was similarly interrupted at a town hall for liberal activists in Phoenix last month. Johnson beckoned Sanders to stand closer as she spoke — he refused.
The Westlake protesters would not let Sanders take the microphone, prompting rally organizer Robby Stern to say the event was over because the demonstrators were determined to stop it.
Sanders left the stage and walked through the crowd, greeting supporters, before leaving in a white Jeep for a fundraiser at the Comet Tavern on Capitol Hill.
At the Comet, reporters were barred, but Sanders could be heard by a crowd watching outside through open windows.
“When we stand together, when black and white stand together, when gay and straight stand together, when women and men stand together,” Sanders told the cheering crowd, which paid $200 to $1,000 to get in, “when we stand together, there is nothing, nothing, that we cannot accomplish.”
In a written statement addressing the Westlake protest, Sanders said he was “disappointed that two people disrupted a rally attended by thousands … I was especially disappointed because on criminal-justice reform and the need to fight racism there is no other candidate for president who will fight harder than me.”
In a news release posted on social media, local Black Lives Matter activists said they were holding Sanders and other white progressives accountable for failing to support their movement.
Citing the anniversary of Brown’s death, they said, “We honor black lives by doing the unthinkable, the unapologetic, and the unrespectable.”
Activists with the movement have shut down Seattle streets and local events before, arguing such direct action is needed to shake people out of complacency over the deaths of black men and women at the hands of police. In December, they disrupted a Christmas tree-lighting ceremony at Westlake.
Some Sanders supporters were chagrined at the way his speech was cut off and said the protesters hurt their own cause.
“Why would they pick Bernie Sanders to do this to? He has stuck up for civil rights,” said Diane Jerich-Domin, of Port Ludlow, Jefferson County, who added that she had attended Black Lives Matter protests after Ferguson.
Gerald Hankerson, president of the Seattle King County NAACP, said he was “torn” by the protest. Hankerson spoke at the Westlake rally and led the crowd at one point in a chant of “Black Lives Matter.”
But he said he was surprised at how hostile some in the liberal crowd were to the protesters.
“I know they were there to hear Bernie, but what was missed was the message of these two women,” Hankerson said. “I would have loved to have seen Bernie respond to what they wanted.”
This video contains language that some viewers may find offensive.
This video contains language that some viewers may find offensive. Video courtesy of Adam Ward.
At the UW event, 12,000 supporters flooded the arena and 3,000 more were in the overflow crowd outside, the fire marshal said.
Lynn Bloss, 70, said she’d been aware of Sanders for a long time, but only recently became a big supporter as he seeks the presidency. She has a disabled son, so Sanders’ support for expanding health care and education are particularly important to her and her husband.
A former Clinton fan, Bloss said she found Sanders more genuine. “He’s invigorating and he’s authentic,” Bloss said. “I feel like we’re really getting the truth from him.”
A self-proclaimed democratic socialist, the independent senator, 73, had been expecting a warm welcome in Seattle, known for its liberal politics.
A few thousand had gathered at Westlake for the 1 p.m. event, which featured hours of speeches from local activists and politicians in favor of protecting and expanding Social Security, Medicare and other programs that have kept millions out of poverty.
Before the ending disruption, the event had a celebratory air, with musical acts and a crowd united in chanting to “Scrap the Cap” — referring to a proposal to tax rich people on all their earnings instead of just the first $118,500, to protect and expand Social Security.
A group of Seattle police on bikes and on foot monitored the event, but no arrests were made. Detective Patrick Michaud said rally organizers “asked us not to move up and make any arrests.”
Stern, the longtime local labor activist who emceed the rally, said while it was “a very disappointing ending, the program itself was fantastic” and got out the message of the importance of preserving and expanding Social Security.
Sanders’ visit was part of a West Coast swing. He is scheduled to speak in Portland on Sunday and in Los Angeles on Monday. | – Liberals cussing out black protesters in Seattle? Apparently it happened: Bernie Sanders was starting a speech at Westlake Park yesterday when two female activists for Black Lives Matter snatched his microphone and demanded people's attention, the Seattle Times reports. "If you do not listen … your event will be shut down," one of them said. Organizers of the event—intended to celebrate Social Security's 80th birthday—relented, allowing protesters to commemorate today's one-year anniversary of the Michael Brown shooting. But some in the mostly white crowd called for the protesters' arrest while others booed or chanted against them. The Vermont senator tried taking the mic back at one point but couldn't do so, Politico reports. "I was going to tell Bernie how racist this city is, filled with its progressives, but you did it for me," said protester Marissa Johnson, who accused people present of "white supremacist liberalism." She mentioned police issues in Seattle and called for 4 1/2 minutes of silence for Brown, during which some shouted profanities. As for Sanders, the Democratic presidential candidate went on to give a speech about the need for financial equality to 15,000 supporters at Hec Edmundson Pavilion. He also released a statement saying he was “disappointed that two people disrupted a rally attended by thousands" and cited his belief in criminal-justice reform. Black Lives Matter activists had interrupted a public interview with Sanders in Phoenix just last month. |
this study adopted applied research approach in two phases . in the first step , this study conducted theoretical health equity audit models in the texts , and then , employed the delphi technique.9 this phase was conducted to study the experiences of other countries in this regard and select the most appropriate model for iranian health system . the models of health equity audit of canada , australia , uk and switzerland were reviewed and the uk 's model for iranian case was adopted .
the uk 's health administration system is the same as the current health management system of iran ( e.g. , referral system for needy and villagers).10 there is also existence of an equity - oriented health system in uk , considering the importance of preparing and applying specific and practical patterns in health evaluation and principles of the 60-year - old national health service ( nhs ) in uk with the commitment to equal access and treatment for all , regardless of social class , income or status,11 and its positive actions in the field of health equity audit .
however , scope of this research included the nhs of uk ; and the time scope was from the past to the present .
uk 's information was collected by using the available on - line data bases , such as library resources and information released by nhs , the electronic databases like iranmedex , pubmed , emerald , and science direct .
this study applied a questionnaire in order to gathering data.12 questionnaire was made according to the uk model .
it was categorized in four major sections : indicators , equity audit topics , organizations responsible for carrying out equity audit model and health equity audit stages .
the validity of the questionnaire was assessed using the collective opinions of top five academic experts and specialists in health sector .
the questionnaires filled up by 18 academic experts including : scholars with a relevant university degree in health care management , members of expert committees , the people who have enough work experiences ( at least 5 years ) in health institutions , such as the ministry of health , schools of medical sciences and health care centers . finally , with the aim of achieving consensus on the basic model and converting it to the final model , a revision of the earlier model was done , defects ( resulting from the phase ii ) were removed and the re - revised model was sent to the previous experts who participated in phase ii . once again , their views were collected .
this process repeated several times until a concord was achieved and the final model were extracted .
this phase was conducted to study the experiences of other countries in this regard and select the most appropriate model for iranian health system .
the models of health equity audit of canada , australia , uk and switzerland were reviewed and the uk 's model for iranian case was adopted .
the uk 's health administration system is the same as the current health management system of iran ( e.g. , referral system for needy and villagers).10 there is also existence of an equity - oriented health system in uk , considering the importance of preparing and applying specific and practical patterns in health evaluation and principles of the 60-year - old national health service ( nhs ) in uk with the commitment to equal access and treatment for all , regardless of social class , income or status,11 and its positive actions in the field of health equity audit .
however , scope of this research included the nhs of uk ; and the time scope was from the past to the present .
uk 's information was collected by using the available on - line data bases , such as library resources and information released by nhs , the electronic databases like iranmedex , pubmed , emerald , and science direct .
this study applied a questionnaire in order to gathering data.12 questionnaire was made according to the uk model .
it was categorized in four major sections : indicators , equity audit topics , organizations responsible for carrying out equity audit model and health equity audit stages .
the validity of the questionnaire was assessed using the collective opinions of top five academic experts and specialists in health sector . the questionnaires filled up by 18 academic experts including : scholars with a relevant university degree in health care management , members of expert committees , the people who have enough work experiences ( at least 5 years ) in health institutions , such as the ministry of health , schools of medical sciences and health care centers .
finally , with the aim of achieving consensus on the basic model and converting it to the final model , a revision of the earlier model was done , defects ( resulting from the phase ii ) were removed and the re - revised model was sent to the previous experts who participated in phase ii . once again , their views were collected .
this process repeated several times until a concord was achieved and the final model were extracted .
this phase was conducted to study the experiences of other countries in this regard and select the most appropriate model for iranian health system .
the models of health equity audit of canada , australia , uk and switzerland were reviewed and the uk 's model for iranian case was adopted .
the uk 's health administration system is the same as the current health management system of iran ( e.g. , referral system for needy and villagers).10 there is also existence of an equity - oriented health system in uk , considering the importance of preparing and applying specific and practical patterns in health evaluation and principles of the 60-year - old national health service ( nhs ) in uk with the commitment to equal access and treatment for all , regardless of social class , income or status,11 and its positive actions in the field of health equity audit .
however , scope of this research included the nhs of uk ; and the time scope was from the past to the present .
uk 's information was collected by using the available on - line data bases , such as library resources and information released by nhs , the electronic databases like iranmedex , pubmed , emerald , and science direct .
this study applied a questionnaire in order to gathering data.12 questionnaire was made according to the uk model .
it was categorized in four major sections : indicators , equity audit topics , organizations responsible for carrying out equity audit model and health equity audit stages .
the validity of the questionnaire was assessed using the collective opinions of top five academic experts and specialists in health sector .
the questionnaires filled up by 18 academic experts including : scholars with a relevant university degree in health care management , members of expert committees , the people who have enough work experiences ( at least 5 years ) in health institutions , such as the ministry of health , schools of medical sciences and health care centers . finally , with the aim of achieving consensus on the basic model and converting it to the final model , a revision of the earlier model was done , defects ( resulting from the phase ii ) were removed and the re - revised model was sent to the previous experts who participated in phase ii . once again , their views were collected .
this process repeated several times until a concord was achieved and the final model were extracted .
confidentiality of interviews was respected . overall analysis of results was done without insertion of the names .
a total of 18 academic experts were identified and the questionnaires were distributed among them in university , separately .
17 academic experts provided a positive response towards implementation of health equity audit in iran , and only one did not provide a direct answer ; instead he stated that , we must set concepts , principles and cultural infrastructures of equity first , and then audits may be performed .
agreeable topics , performing agencies , equity audit stages , and equity indicators in the uk health system were identified and ultimately proposed viewpoints in the above fields were provided and the proposed health equity audit model for iran was presented as follows .
health equity audit is a tool that enables the identification and redistribution of resources on the basis of need.11 the study results based on expert opinions is that using health equity audit in iran 's health system is valuable : 1 . to increase awareness of its application across the country , 2 . to document its practical ability in health centers , 3 . to increase its acceptance politically , 4 . to do self - assessment equity in health centers , 5 .
to prevent health inequalities in the future , 6 . to consider local issues around the country and local population groups with special health needs , 7 . to compare health inequalities in similar groups , 8 . for focusing on community health issues to identify the cumulative effects of unequal access to services , 9 .
to ensure that new initiatives and current priorities to reduce health inequalities have been in agreement with the health ministry schemes , 10 .
for the appropriate investment in reducing health inequalities , and 11 . for the planning , implementation and evaluation of local interventions .
on the other hand , considering no investigation has been done about health equity audit in iran and unfamiliarity with this topic , the obvious achievements of the study on identification of equity audit model was focusing on four major sections including indicators , equity audit topics , audit organizations to perform equity and health equity audit stages in uk and ultimately proposing a health equity audit model for iran .
since the selection of the topics related to health equity audit is based on the national and local preferences , 28 main axes ( with 195 minor axes ) in the uk health system were studied.5 themes such as quitting smoking , stroke , childhood obesity , coronary heart disease , and diabetes were the top five main topics in health equity audit in the uk health equity system.13 in contrast with the 28 main axes above , access to primary care , immunization and vaccination , family planning and contraceptive services , children 's health and mental health were proposed as five priority ( or primary ) axes in iran .
since the organizations involved in the health equity audit process of uk are discordant with iran , just to inform experts , information on the uk was given to them , and 9 organizations which could participate in equity audit process in iran were listed in the questionnaire . finally , after considering experts comments , suggested items are presented in table 2 .
considering that the iranian government is the trustee , the result shows that the priority in equity audit for iran will be with independent organizations .
health equity audit topics in united kingdom compared with the topics agreed by experts for health equity audit in order of preference for iran .
audit organizations to perform equity in united kingdom compared with the proposed audit organizations to perform equity agreed by experts in order of preference for iran health equity audit stages in united kingdom model compared with the health equity audit stages in the proposed model for iran health equity audit steps in the proposed model for iran in iran according to a gap in the field of health equity , reviewing the health equity audit process , priority is to identify equity profile , identifying the gap and then , reaching an agreement with partners on issues with most dilated gaps ; and another stage is to agree on priorities for action , but in uk the priority is to agree on priorities and partners , and preparation of an equity profile and analyzing the data and then identifying the use of evidence for effective local action . it should be mentioned that from the six stages of the health equity audit review , expert comments in the stages 1 , 2 and 3 , were different from those in the uk model , but their comments were similar to those in the uk model in stages 4 , 5 and 6 .
one of the important achievements of this study was providing details of the proposed model of health equity audit for iran for offering better understanding of the equity audit topic and optimizing its capabilities in iran 's health system .
table 4 contains health equity and health inequality indicators under three main parts : demographic indicators ( with 6 sub - sections ) , community health status indicators ( with 7 sub - sections ) , indicators of health care services ( with 3 sub - sections ) and samples of uk 's and iran 's indicators in the relevant columns were compared .
the purpose of this part was to help health practitioners and stakeholders to promote the knowledge of community health status . comparing sample indicators in united kingdom health system with those in iran finally
, it can be said that , although in iran the government executes the affairs now , but it could be the responsibility of independent proposed boards to make a plan about , establishing equity and performing stability , reducing social and economic inequalities , reducing the income gap and equitable distribution of income in the country , reducing poverty , deprivation and empowering the poor , through targeted resource allocation and efficient social security payments and subsidies , comprehensive poverty alleviation planning and social equity , and carrying out all activities associated with economic development according to the health equity audit . also , to generate relevant evidence and take appropriate actions to tackle health inequities , local authorities need a variety of tools . in order to facilitate a comprehensive understanding of health systems performance , these tools should : 1 . adopt a multi - sectoral approach , 2 .
be operationally feasible and sustainable.10 authors believe that future studies on the formation of health equity audit team with attendance of independent proposed boards ( citing findings in table 4 ) in iran , conducting independent analytical research about health equity in iran and ultimately , implementing the model presented on this study and analyzing its results to promote health equity in iran are necessary .
sk and shahzm contributed equally to design , data collection and review , questionnaire preparation , review and comments by experts and writing the manuscript . | background : health equity audit , as an alternative solution , is a process by which local partners systematically review inequalities in the patients ` health , their access to appropriate services and health system outputs .
then , necessary activities needed in order to have more equitable services are agreed on and these concurrences become the executive scheme and action initiates .
therefore , it is pivotal for health care organizations to pay special attention to this important topic .
the objective of the current study was to review the health equity audit model in different countries to gather viewpoints of various involved groups in health sector , particularly health experts , and to offer a practical and appropriate model for health equity audit in iran.methods:this study adopted applied research approach in two phases .
in the first step , this study conducted theoretical health equity audit models in the texts ; the experiences of other countries were studied and the most appropriate model for iranian health system was selected . in the second step , this study employed the delphi technique . according to the delphi technique the questionnaire applied in order to gather data and
then , the final model was extracted.results:agreeable topics , performing agencies , 6 equity audit stages , and equity indicators under 3 main parts with 16 sub - sections were elaborated and viewpoints of iranian experts in the above fields were gathered and presented as the proposed health equity audit model for iran.conclusions:this study reviewed the model of health equity audit for uk and provided a comparative model for health system of iran with respect to the opinions of academic experts . |
despite recent advances in imaging modalities , it is very difficult to distinguish benign lesions from malignant lesions presenting as polypoid lesions of the gallbladder ( plg ) .
the current consensus regarding a treatment strategy for plg is that a solitary , sessile polyp larger than 1 cm and a patient older than 60 years should be removed surgically because it can mask malignancy .
we treated a patient with an inflammatory polyp of the gallbladder mimicking early polypoid cancer and discuss this rare entity .
a 69-year - old male was admitted to our hospital with a plg that was found incidentally .
tumor markers such as carcinoembryonic antigen and cancer antigen 19 - 9 were also within normal range .
ultrasonography ( us ) revealed a polypoid lesion with isodensity of the liver measuring 16 mm in maximum size in the fundus of the gallbladder . enhanced computed tomography ( ct ) demonstrated marked enhancement of the polyp , although it was not clearly detected on unenhanced ct ( fig .
1a ) . magnetic resonance imaging showed a subpedunculated and smooth - surfaced polyp with the upper two - thirds of its mass constricted . with a tentative diagnosis of early polypoid cancer of the gallbladder
intraoperative us showed a mushroom - shaped polyp with hyperechoic spots on the surface and with an inner echopenic area ( fig .
resected specimens revealed a smooth - surfaced polyp with the upper two - thirds of its mass constricted ( fig .
histological study revealed a nonneoplastic polyp with edematous stroma and infiltration of lymphcytes and plasmacytes with partial formation of lymph follicles .
atypical epithelium was not present , although the surface epithelium was complicated and intestinal metaplasia was found .
a microscopic intramural calculus was present , although there were no macroscopic stones in the gallbladder ( fig .
inflammatory polyps of the gallbladder are defined as tumor - like lesions in the category of benign tumors and tumor - like lesions of the gallbladder and extrahepatic bile ducts that have radiologic manifestations . among the tumor - like lesions of the gallbladder , inflammatory polyps are relatively rare , accounting for 1.4 to 12% of plg in recent published data ; hence cholesterol polyps comprise the majority of nonneoplastic polyps of the gallbladder .
inflammatory polyps of the gallbladder histologically consist of vascular connective tissue containing inflammatory infiltrates , and there is hyperplastic epithelial invagination .
these polyps appear to be the result of enlargement and fusion of villi due to chronic inflammation . in the present case ,
very few case reports of inflammatory polyps of the gallbladder have been published , so the typical characteristics of imaging findings have not been described precisely .
this differentiation of ultrasonographic findings may depend on the size of the polyp ; the former measured 15 8 mm and the latter 8 3 mm .
reported the presence of a hyperechoic line around the inflammatory polyp , as intraoperative us showed hyperechoic spots on the surface of the polyp in the present case .
this finding probably depends on the difference of density originating from the complication of the epithelial surface of the polyp .
endoscopic us showed , however , that hyperechoic spots were nonspecific findings for an inflammatory polyp because aggregations of hyperechoic spots , which represented multiple granules of cholesterosis , have also been recognized in a high percentage of cholesterol polyps .
furukawa et al . reported that not all cholesterol polyps and hyperplastic polyps were detected on unenhanced ct , and concluded that the configuration of polypoid lesions depicted on enhanced ct and visualization of them on unenhanced ct are helpful in differentiating neoplastic lesions that should be resected from other benign lesions . in conclusion , intraoperative us as well as endoscopic us could be helpful to differentiate benign polypoid lesions from malignant ones .
the histological manifestation of inflammatory polyp of the gallbladder should guide the examination of us findings . | we treated a 69-year - old male with a 16-mm polyp of the gallbladder . enhanced computed tomography demonstrated marked enhancement . with a tentative diagnosis of early polypoid cancer of the gallbladder
, open cholecystectomy was performed .
intraoperative ultrasound showed hyperechoic spots on the surface of the polyp with an inner echopenic area .
the histological diagnosis was an inflammatory polyp that manifested nonneoplastic , edematous stroma , and infiltration of lymphcytes and plasmacytes . |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Radio Free Iran Act''.
SEC. 2. FINDINGS.
Congress makes the following findings:
(1) It is the policy of the United States to support the
right of the people of Iran to seek, receive, and impart
information and ideas through any media, regardless of
frontiers, in accordance with article 19 of the Universal
Declaration of Human Rights.
(2) Consonant with this policy, radio broadcasting to Iran
may be effective in furthering the open communication of
accurate information and ideas about Iran to the people of
Iran.
(3) Such broadcasting to Iran, operated in a manner not
inconsistent with the broad foreign policy of the United States
and in accordance with high professional standards, would be in
the national interest.
SEC. 3. RADIO BROADCASTING TO IRAN.
(a) In General.--In order to carry out the objectives set forth in
section 2, the United States Information Agency shall provide for the
open communication of information and ideas on Iran through the use of
radio broadcasting to Iran. Radio broadcasting to Iran under this
section shall serve as a consistently reliable and authoritative source
of accurate, objective, and comprehensive news on Iran.
(b) Requirements Relating to Broadcasting.--(1) Radio broadcasting
under subsection (a) shall be provided in accordance with standards
that ensure the broadcast of programs which are objective, accurate,
and balanced, and which present a variety of views. Such standards
shall be established by the board established under section 4.
(2) Radio broadcasting under subsection (a) shall be provided in
the Farsi language.
(c) Designation of Broadcasts.--Any program of United States
Government radio broadcasts in the Farsi language under this section
shall be designated ``Radio Free Iran''.
(d) Relationship With Other Radio Service to Iran.--It is the sense
of Congress that radio broadcasting under this section supplement and
not supplant other radio broadcasting and radio broadcasting services
to Iran in the Farsi language that are provided by the United States
Government.
(e) Authority To Contract.--The Director of the United States
Information Agency may carry out this section by means of grants,
contracts, and leases and by such other means as the Director
determines appropriate. Any grant, contract, or lease under this
subsection shall specify that payment thereunder by the Director is
subject to the availability of appropriations therefor.
(f) Assistance From Other Government Agencies.--The Director may
secure on a reimbursable basis from any department or agency of the
Federal Government, with the concurrence of the head of the department
or agency, any technical or administrative support or services
(including personnel and property) that the Director may require in
order to provide radio broadcasting to Iran under this section. Any
reimbursement under this subsection shall be credited to the
appropriation from which the support or services was derived.
SEC. 4. ADVISORY BOARD.
(a) In General.--There is hereby established an advisory board to
be known as the Advisory Board for Radio Free Iran (in this section
referred to as the ``Board'').
(b) Membership Matters.--(1) The Board shall be composed of eight
members of whom--
(A) four shall be appointed by the President;
(B) two shall be appointed by the President pro tempore of
the Senate, upon the recommendation of the majority and
minority leaders of the Senate; and
(C) two shall be appointed by the Speaker of the House of
Representatives, in consultation with the minority leader of
the House of Representatives.
(2) Members shall be appointed for terms of 4 years. Any vacancy in
the Board shall not affect its powers but shall be filled in the same
manner as the original appointment.
(3) The President shall designate one member of the Board to be the
Chairman.
(c) Duties.--The Board shall have the following duties:
(1) To establish standards for the broadcast of programs
under section 3, which standards shall ensure that such
programs are objective, accurate, and balanced, and present a
variety of views.
(2) To monitor the broadcast of programs under that section
in order to ensure that the programs meet the standards so
established.
(d) Compensation.--(1) Each member of the Board who is not an
officer or employee of the Federal Government shall be compensated at a
rate equal to the daily equivalent of the annual rate of basic pay
prescribed for level IV of the Executive Schedule under section 5315 of
title 5, United States Code, for each day (including travel time)
during which such member is engaged in the performance of the duties of
the Board. All members of the Board who are officers or employees of
the United States shall serve without compensation in addition to that
received for their services as officers or employees of the United
States.
(2) The members of the Board shall be allowed travel expenses,
including per diem in lieu of subsistence, at rates authorized for
employees of agencies under subchapter I of chapter 57 of title 5,
United States Code, while away from their homes or regular places of
business in the performance of services for the Board.
(e) Procurement of Supplies and Services.--The Board may, to the
extent it considers necessary to carry out its duties under this
section, procure supplies, services, and other personal property,
including specialized electronic equipment.
SEC. 5. AUTHORIZATION OF APPROPRIATIONS.
(a) Authorization of Appropriations.--There are authorized to be
appropriated for the United States Information Agency for fiscal year
1996 such sums as may be necessary for purposes of carrying out this
Act, in-cluding the activities of the Board established under section
4.
(b) Availability of Funds.--Amounts appropriated under this section
shall remain available until expended. | Radio Free Iran Act - Directs the United States Information Agency to provide for the open communication of information and ideas on Iran through the use of radio broadcasting to Iran. Designates any U.S. Government radio broadcasts in the Farsi language to Iran as "Radio Free Iran."
Establishes the Advisory Board for Radio Free Iran to establish standards to ensure that programs are objective, accurate, and balanced and present a variety of views.
Authorizes appropriations. |
thyroid cancer is one of the most common types of endocrine malignancy , the incidence rate of which has rapidly increased during previous years ( 1,2 ) .
it has been estimated that the annual number of cases of thyroid cancer diagnosed in the usa and the associated mortality rate are 12.9/100,000 and 0.5/100,000 individuals , respectively ( 3 ) .
papillary thyroid cancer ( ptc ) , characterized by papillary architecture , psammoma bodies and specific nuclear features , including nuclear orientation , nuclear chromatin and nuclear grooving , is the major form of thyroid cancer , accounting for 8085% of all thyroid malignancies ( 4 ) .
although ptc has a favorable prognosis , certain cases exhibit aggressive clinical characteristics , including invasion and metastasis , and the management of ptc remains controversial ( 5,6 ) .
therefore , it is essential to investigate the molecular mechanisms of ptc and identify potential biomarkers , which may be beneficial for improving treatment .
the current understanding of the molecular mechanisms of ptc has improved significantly , particularly with the development of next generation sequencing and microarray technology .
it has been reported that mutations of braf ( t1796a and v599e ) causing the activation of serine / threonine kinase may be an alternative mechanism of oncogenic mitogen - activated protein kinase pathway activation and are important in the development of ptc ( 79 ) .
the chemokine receptor , cxcr7 not only activates the phosphoinositide 3-kinase / akt and nuclear factor-b signaling pathways , but it also downregulates the notch signaling pathway to regulate the growth and metastasis of ptc , according to gene expression profiling analysis of ptc ( 10 ) .
amyloid precursor protein is overexpressed in ptc and may become a potential novel therapeutic target for ptc ( 11 ) .
it has been revealed that certain important upregulated micrornas ( mirs ) , including mir-221 , mir-222 and mir-146 , and the regulation of kit are involved in the pathogenesis of ptc , based on previous microarray analysis of gse3467 ( 12 ) .
zhu et al ( 13 ) showed that trefoil factor 3 , cut - like homeobox 2 and forkhead box protein a2 are associated with the development of ptc , and the differentially expressed genes ( degs ) are primarily associated with positive regulation of gene expression , gene transcription and metabolic processes . in the previous study by zhu et al ( 13 )
only the gse3678 dna microarray data set was downloaded for deg screening and subsequent enrichment analysis . in the present study , two dna microarray data sets , gse3467 and gse3678 ,
the degs found to be simultaneously differentially expressed in the tumor samples of these two data sets were screened for enrichment analysis and interaction network construction .
gene expression profiles . the two gene expression profiling data sets , gse3467 and gse3678 , were downloaded from the gene expression omnibus ( geo ; http://www.ncbi.nlm.nih.gov/geo/ ) ( 14 ) .
gse3467 ( 12 ) consisted of 18 paired tumor and normal thyroid tissue samples from nine patients with ptc .
the gse3678 data set contained seven ptc samples and seven paired normal thyroid tissue samples . the platform used for these two data sets was the gpl570 [ hg - u133_plus_2 ] affymetrix human genome u133 plus 2.0 array .
the probes without annotation of the gene expression profiles were filtered , and the probes were transformed into gene symbols .
the average value of a gene symbol corresponding to multiple probes was calculated for the expression level analysis . the log2 transformation
, background correction and data normalization were performed using the genechip robust multi - array analysis ( gcrma ) method within bioconductor ( http://www.bioconductor.org ) ( 15 ) .
the degs were screened out by using the linear models for microarray analysis ( limma ) package in r software ( 16 ) with the cut - off criteria of adjusted p<0.01 and |log2 fold - change ( fc)|>2 . functional and pathway enrichment analyses . functional and pathway enrichment analyses for the common degs were performed using the database for annotation , visualization and integrated discovery online tools ( 17 ) based on the gene ontology ( go ) ( 18 ) and kyoto encyclopedia of genes and genomes ( 19 ) databases .
the go terms in three categories , including biological process , cellular component and molecular function , were identified with p<0.05 . for pathway enrichment analysis , p0.05 was set as the threshold .
construction and analysis of the protein - protein interaction ( ppi ) network . the physical ppis and pathway interactions
were selected for ppi network construction using the gene multiple association network integration algorithm ( http://www.genemania.org/ ) ( 20 ) plug - in of cytoscape software ( www.cytoscape.org ; version 3.4.0 ) .
the representative subnetwork containing nodes with high levels of interconnection was further derived from the ppi network using molecular complex detection software ( baderlab.org/software/mcode ) ( 21 ) .
in addition , the potential drugs of the hub degs in the subnetwork were searched using the drugbank database ( www.drugbank.ca ) ( 22 ) and the potential drug - like ligands , which interacted with the genes , were screened from the diverse - lib database in mtiopenscreen ( bioserv.rpbs.univ-paris-diderot.fr/services/mtiopenscreen ) ( 23 ) according to lipinski 's rule of five ( 24 ) .
identification of degs . following data preprocessing , the standardized expression profiling data showed that the median values of gene expression were almost at the same level , indicating that the degree of standardization was sufficient to be used for the subsequent analysis ( fig .
a total of 384 and 262 degs were identified for gse3467 and gse3678 , respectively .
in addition , 167 genes were found to be simultaneously differentially expressed in the tumor samples of these two data sets ( fig .
among these 167 common degs , 77 genes were upregulated and 90 genes were downregulated .
the correlation of the expression values for the 167 genes was 0.97 ( p<2.2e-16 ; fig .
the common degs were primarily associated with the cellular components of the plasma membrane ( p=2.60e-05 ) and integral to the membrane ( p=0.002429 ) .
certain common degs , including lc26a4 , gabrb3 , gabrb2 and clcnkb , were significantly enriched in the anion transmembrane transporter activity ( p=4.45e-04 ) and chloride anion binding ( p=0.005756 ) .
in addition , serpina1 , cited1 and ghr were involved with response to steroid hormone stimulus ( p=0.001849 ) .
fn1 , lamb3 and col13a1 were enriched in cell adhesion ( p=0.011121 ; table i ) .
in addition , two significant pathways were enriched for the common degs ( table ii ) .
the aldh1a3 , aox1 , hgd , adh1b and tpo genes were significantly involved in the tyrosine metabolism pathway ( p=0.001 ) .
another five common degs , including nrcam , ncam1 , cldn1 , cldn10 and cdh3 , were enriched in the cell adhesion molecules pathway ( p=0.05 ) . interaction network analysis .
there were eight common degs , of which met , serpina1 , lgals3 , fn1 , lamb3 , krt19 and col13a1 were upregulated , and tnfrsf11b was downregulated ) in the constructed subnetwork ( fig .
3 ) . the fn1 deg can interact with serpina1 , lgals3 , tnfrsf11b and lamb3 .
there were also pathway interactions between any two of the fn1 , col13a1 and lamb3 degs .
the potential drugs for fn1 and serpina1 were examined further , as these two degs showed higher degrees in the interaction subnetwork and may be critical in the regulatory process .
the results revealed that two drugs , lanoteplase and ocriplasmin , were found for fn1 , and four potential drugs , -mercaptoethanol , recombinant 1-antitrypsin , ppl-100 and api , were found for serpina1 ( table iii ) .
lanoteplase is currently under clinical investigation and ocriplasmin , whose pharmacological action involves the cleavage of fibronectin protein , has been approved by the food and drug administration ( 25 ) . for serpina1 ,
-mercaptoethanol is during experimental stage and the other three drugs are under clinical investigation . in addition , five potential drug - like compounds with binding energies below 8.4 were screened out from the diverse - lib database in mtiopenscreen ( table iv ) .
the 24350490 compound , with a binding energy of 8.7 kcal / mol , has six hydrogen bond acceptors and one hydrogen bond donor .
another compound , 17506143 , with a binding energy of 8.6 kcal / mol has seven hydrogen bond acceptors and one hydrogen bond donor . the structural interactions between serpina1 and these two drug - like compounds
in the present study , 167 genes were identified to be simultaneously differentially expressed in the tumor samples of gse3467 and gse3678 .
the subsequent pathway enrichment analysis revealed that aldh1a3 , aox1 , hgd , adh1b and tpo were significantly involved in tyrosine metabolism .
several studies have revealed that the protooncogene , ret , which encodes a tyrosine kinase cell surface receptor , is involved in the oncogenesis of ptc by activating its tyrosine kinase , either by rearrangement or mutation ( 26,27 ) .
it has been confirmed that the mrna expression level of tpo is markedly suppressed leading to low thyroid peroxidase activity in ptc ( 28 ) .
thyroid peroxidase oxidizes iodide to form active iodine for addition onto tyrosine residues on thyroglobulin for the production of thyroid hormones ( 29 ) . in the present study , tpo
therefore , aldh1a3 , aox1 , hgd , adh1b and tpo may be important in ptc via their involvement in the tyrosine metabolism pathway .
by contrast , the nrcam , ncam1 , cldn1 , cldn10 and cdh3 were significantly enriched in the pathway of cell adhesion molecules .
molecules associated with cell adhesion , for example icam-1 , are known to be involved in papillary growth and proliferative capacity ( 30 ) .
the pathway enrichment analysis indicated that these common degs are involved in the pathogenesis and progression of ptc by regulating the pathways of tyrosine metabolism and cell adhesion molecules .
the representative subnetwork derived from the interaction network in the present study contained seven upregulated common degs ( met , serpina1 , lgals3 , fn1 , lamb3 and col13a1 ) and one downregulated deg ( tnfrsf11b ) .
the met , serpina1 , lgals3 and fn1 degs have been identified to be the potent biomarkers for ptc in previous studies ( 31,32 ) .
the expression levels of fn1 and met have been also reported to be upregulated in papillary thyroid carcinoma ( 33 ) .
the functional enrichment analysis revealed that fn1 was significantly enriched in the plasma membrane , extracellular matrix and cell adhesion .
vasko et al ( 34 ) showed that epithelial - to - mesenchymal transition is common in ptc invasion .
it has been demonstrated that the genes differentially expressed in aggressive ptc are primarily associated with cell adhesion ( 35 ) .
in addition , fn1 can interact with serpina1 , lgals3 , tnfrsf11b and lamb3 , according to the subnetwork .
these results suggested that fn1 might be involved in pct by regulating the epithelial - to - mesenchymal transition and interacting with other degs .
therefore , ocriplasmin may be of assistance in the prevention or treatment of ptc due to the cleavage of fibronectin .
another common deg with a higher degree , serpina1 , was significantly associated with the functions of response to steroid hormone stimulus and response to estrogen stimulus in the present study .
vierlinger et al ( 37 ) showed that serpina1 can be considered as a single marker for ptc . in papillary thyroid tumors and normal thyroid tissue ,
estrogen and progesterone receptors have been identified in thyroid tissue responsive to steroid hormones ( 38 ) .
kawabata et al ( 39 ) reported estrogen receptor ( er ) is expressed at high levels in papillary thyroid cancer , suggesting that er may be involved in the development , physiology and pathology of papillary carcinoma .
therefore , upregulated expression levels of serpina1 may contribute to the response to steroid hormones in ptc . in the present study ,
ser47 are critical for the binding of compounds by forming hydrogen bonds ( 40 ) , the amino acid around the pocket , which binds with compounds , may be critical for the function of serpina1
. therefore , -mercaptoethanol and recombinant 1-antitrypsin may be the potential drugs for ptc .
in addition , the gene and protein expression levels of important degs may be better confirmed using experimental studies . in conclusion
, the common degs identified from gse3467 and gse3678 were found to have the potential for use as candidate biomarkers for ptc .
the upregulated expression levels of fn1 and serpina1 may be involved in ptc by regulating the epithelial - to - mesenchymal transition and response to steroid hormones , respectively .
furthermore , ocriplasmin , -mercaptoethanol and recombinant 1-antitrypsin may be potential drugs for the treatment of ptc . in further investigations , confirmation of the expression levels of important genes is required , as is the examination of ptc at different stages . | the present study aimed to systematically examine the molecular mechanisms of papillary thyroid cancer ( ptc ) , and identify potential biomarkers and drugs for the treatment of ptc .
two microarray data sets ( gse3467 and gse3678 ) , containing 16 ptc samples and 16 paired normal samples , were downloaded from the gene expression omnibus database . the differentially expressed genes ( degs )
were identified using the linear models for microarray analysis package .
subsequently , the common degs were screened for functional and pathway enrichment analysis using the database for annotation visualization and integrated discovery .
the representative interaction subnetwork was further derived using molecular complex detection software .
in addition , the potential drugs for the hub degs in the subnetwork were screened from drugbank and the potential drug - like ligands , which interacted with genes , were selected using mtiopenscreen .
a total of 167 common degs , including 77 upregulated and 90 downregulated degs , were screened .
the common degs were associated with the functions of plasma membrane , extracellular matrix , response to steroid hormone stimulus and cell adhesion , and the pathways of tyrosine metabolism and cell adhesion molecules were significantly enriched .
a total of eight common degs ( met , serpina1 , lgals3 , fn1 , tnfrsf11b , lamb3 and col13a1 ) were involved in the subnetwork .
the two drugs , lanoteplase and ocriplasmin , and four drugs , -mercaptoethanol , recombinant 1-antitrypsin , ppl-100 and api , were found for fn1 and serpina1 , respectively .
the common degs identified may be potential biomarkers for pct .
fn1 and serpina1 may be involved in ptc by regulating epithelial - to - mesenchymal transition and responding to steroid hormone stimuli , respectively .
ocriplasmin , -mercaptoethanol and recombinant 1-antitrypsin may be potential drugs for the treatment of ptc . |
the icecube collaboration reported 37 events ranging from 60tev to 3pev within three years of operation , correspond to a @xmath2 excess over the background atmospheric neutrinos and muons@xcite .
the observed events can be fitted by a hard spectra ( @xmath3 ) with @xmath4 and a cutoff above 2pev , implied by the non - detection of higher energy events , or alternatively by a slightly softer but unbroken power - law spectrum with index @xmath5@xcite .
the best - fit single - flavor astrophysical flux ( @xmath6 ) is @xmath7 , assuming a @xmath1 spectrum .
the sky distribution of the these events is consistent with isotropy @xcite , implying an extragalactic origin or possibly galactic halo origin @xcite , although a fraction of them could come from galactic sources @xcite .
the source of these icecube neutrinos is , however , unknown .
jets and/or cores of active galactic nuclei ( agn ) , and gamma - ray burst ( grbs ) have been suggested to be possible sources , where the photo - hadronic ( e.g. , @xmath8 ) reaction is typically the main neutrino generation process @xcite . on the other hand , starburst galaxies and galaxy clusters
may also produce pev neutrinos , mainly via the hadronuclear ( e.g. , @xmath0 ) reaction @xcite . in this paper
, we concern the @xmath0 process in starburst galaxies , following earlier works in which remnants of supernovae in general @xcite or a special class of supernova
hypernovae @xcite in starburst galaxies accelerate cosmic rays ( crs ) , which in turn produce neutrinos by interacting with the dense surrounding medium during propagation in their host galaxies . here
we use starburst galaxies to mean those galaxies that have much higher specific star formation rates ( ssfr ) than the `` main sequence '' of star - forming galaxies . to produce neutrinos with energy @xmath9
, we require a source located at redshift @xmath10 to accelerate protons to energies of @xmath11 @xcite .
it is suggested that semi - relativistic hypernova remnants in starburst galaxies , by virtue of their fast ejecta , are able to accelerate protons to eev energies .
alternatively , assuming sufficient amplification of the magnetic fields in the starburst region , normal supernova remnants might also be able to accelerate protons to @xmath12 ev and produce pev neutrinos @xcite . in @xmath0 collisions , charged and neutral pions are both generated .
charged pions decay to neutrinos ( @xmath13 ) , while neutral pions decay to gamma - rays ( @xmath14 ) .
thus , pev neutrinos are accompanied by high - energy gamma - rays . for a @xmath1 neutrino spectrum with a single - flavor flux of @xmath15 produced by @xmath16 decay ,
the flux of gamma - rays from @xmath17-decay is @xmath18 .
while low - energy gamma - rays may escape freely from the galaxy , very high energy ( vhe ) gamma - rays are absorbed by the soft photons in starbursts , as starburst galaxies are optically thick to vhe gamma rays @xcite .
the absorbed gamma - rays will convert to electron - positron ( @xmath19 ) pairs , which then initiate electromagnetic cascades on soft background photons , reprocessing the energy of vhe photons to low - energy emission and contributing to the diffuse gamma - ray background pairs formed during the cascades is not taken into account . assuming a flat cascade gamma - ray spectrum ( i.e. , @xmath20 with @xmath21 ) ,
the additional contribution to the gamma - ray background flux by the cascade emission can reach as much as @xmath22 .
another component that can contribute to the diffuse gamma - ray emission is @xmath19 pairs produced simultaneously with the neutrinos in the @xmath16 decay .
the ic scatterings of these pairs with infrared photons will produce very high energy photons , which may be absorbed and finally contribute to the cascade gamma - ray component with a flux @xmath23 .
noting that the observed gamma - ray background flux observed by fermi / lat is @xmath24 at @xmath25 gev @xcite , the total diffuse gamma - ray flux associated with pev neutrinos in the @xmath0 scenario would thus contribute @xmath26 of the observed diffuse gamma - ray background in the @xmath25 gev range . ] .
detailed calculations show that the diffuse gamma - ray emission associated with sub - pev / pev neutrinos contribute a fraction @xmath27 to the gamma - ray background when the source density follows the star - formation history and contribute a fraction @xmath28 for non - evolving source density case @xcite .
analytical calculations in @xcite show that this fraction is about @xmath28 . since
other sources , such as agns @xcite or truly diffuse gamma - ray emission from the propagation of ultra - high energy cosmic rays ( uhecrs ) in cosmic microwave and infrared background radiation , also contribute significantly to the diffuse gamma - ray background , a tension between a too high diffuse gamma - ray flux expected from sources and the observed background flux exists .
however , the above calculations do not consider the synchrotron cooling of electron - positron ( @xmath19 ) pairs formed during the cascades . as we argue in this paper
, this synchrotron loss effect could reduce the flux of cascade gamma - ray emission significantly . in this paper , we calculate the accumulated diffuse gamma - ray flux by considering the synchrotron loss of @xmath19 produced by the absorbed gamma - rays in the magnetic fields of the starburst region . for reasonable assumptions of the strength of the magnetic fields in the starburst region , we find that the synchrotron loss dominates over the inverse - compton ( ic ) scattering loss .
since the synchrotron emission goes into energies below gev , the intensity of the cascade gamma - ray component is significantly reduced in the @xmath25 gev energy range . in 2 ,
we first obtain the normalization of the gamma - ray flux of an individual starburst galaxy with the observed neutrino flux . in 3 , we calculate the gamma - ray flux after considering the synchrotron loss .
then in 4 , we calculate the accumulated gamma - ray flux from the population of starburst galaxies .
finally we give our conclusions and discussions in 5 .
to calculate the accumulated diffuse gamma - ray flux , we need to know the the gamma - ray flux from individual starburst galaxies and then integrate over contributions by all the starburst galaxies in the universe .
the gamma - ray flux of an individual galaxy can be then calibrated with the observed neutrino flux , assuming that all the observed neutrinos by icecube are produced by starburst galaxies .
as the neutrino flux is linearly proportionally to the cosmic - ray proton flux and the efficiency in transferring the proton energy to secondary pions , the single - flavor ( @xmath6 ) neutrino luminosity per unit energy from a starburst galaxy is expressed by @xmath29 where @xmath30 , @xmath31 is the cr proton flux at some fixed energy and @xmath32 is the pion production efficiency .
@xmath33 is the index of the proton spectrum ( @xmath34 ) , and we assume @xmath35 , as expected from fermi acceleration , unless otherwise specified .
starbursts have very high star formation rates ( @xmath36 ) of massive stars .
massive stars produce supernova or hypernovae , which accelerate crs in the remnant blast waves , so we expect that @xmath37 . on the other hand ,
the radiation of a large population of hot young stars are absorbed by dense dust and reradiated in the infrared band , so @xmath38 , where @xmath39 is the total infrared luminosity of the starburst galaxy .
thus we expect that @xmath40 , so @xmath41 where @xmath42 is the normalization factor and @xmath43 is the bolometric luminosity of the sun .
the pionic efficiency is @xmath44 , where @xmath45 is the energy - loss time for @xmath0 collisions and @xmath46 is the escape time of protons .
@xmath47 , where the factor 0.5 is inelasticity , @xmath48 is the particle density of gas and @xmath49 is the inelastic proton collision cross section , which is insensitive to proton energy . introducing a parameter @xmath50 as the surface mass density of the gas ( where @xmath51 is the length scale of the starburst region )
, the energy loss time is @xmath52 we use @xmath53 as the reference value and @xmath54 in the following calculations . ] because neutrinos are dominantly produced by high redshift starbursts , as implied by the star - formation history , and high redshift starburst typically have @xmath55 @xcite .
there are two ways for crs to escape from a galaxy .
one is the advective escape via a galactic wind and the other is the diffusive escape .
the advective escape time is @xmath56 where @xmath57 is the velocity of galactic wind .
one can see that protons lose almost all their energy in dense starburst galaxies with @xmath58 , if the advective time is shorter than the diffusive escape time .
little is known about the diffusive escape time in starbursts .
the diffusive escape time can be estimated as @xmath59 , where @xmath60 is the diffusion coefficient , @xmath61 and @xmath62 are normalization factors , and @xmath63 depending on the spectrum of interstellar magnetic turbulence . as in @xcite and @xcite , we assume a lower diffusion coefficient @xmath64 at @xmath65 for starburst galaxies , because the magnetic fields in nearby starburst galaxies such as m82 and ngc253 are observed to be @xmath66 times stronger than in our galaxy and the diffusion coefficient is expected to scale with the cr larmor radius in the case of bohm diffusion .
the fact that no break in the gev - tev gamma - ray spectrum up to several tev from hess observations also suggests a small diffusion coefficient in starburst galaxies @xcite .
the diffusive escape time is thus @xmath67 for @xmath68 @xcite .
alternatively , @xcite assume that crs stream out the starbursts at the average alfvn speed @xmath69 , so @xmath70 where @xmath71 is the magnetic field in the starburst region .
the escape time is the minimum of the advective time and the diffusive time , i.e. @xmath72 . the accumulated neutrino flux can be estimated by summing up the contribution by all starburst galaxies throughout the whole universe , i.e. @xmath73}{h_{0}\sqrt{(1+z)^{3}\omega _ { m}+\omega _ { \lambda } } } dl_{\rm tir}dz,\ ] ] where @xmath74 represents the luminosity function of starburst , @xmath75 , @xmath76 , @xmath77 .
herschel pep / hermes has recently provided an estimation of the ir - galaxy luminosity function for separate classes @xcite , which is a modified - schechter function @xmath78\,.\ ] ] for starburst galaxies , @xmath79 , @xmath80 , @xmath81 , @xmath82 .
@xmath83 evolves with redshift as @xmath84 with @xmath85 . for @xmath86
, it evolves as @xmath87 when @xmath88 , and as @xmath89 when @xmath90 , with @xmath91 , @xmath92 and @xmath93 .
we set @xmath94 and the luminosity ranges from @xmath95 to @xmath96 .
we assume all the observed neutrinos are produced by starburst galaxies , so we can normalize the accumulated diffuse neutrino flux in eq .
( 7 ) with the observed flux at pev energy , i.e. @xmath97 using the central values of the above parameters in the luminosity function ( e.g. @xmath98 , @xmath99 and @xmath100 ) , we get @xmath101 for @xmath35 . varying the values of these parameters within their error , the value of @xmath42 changes within a factor of a few . however , we note that the result of the accumulated gamma - ray flux , as calculated below in 4 , remains almost unchanged .
we also find that the spectrum of the accumulated neutrino flux , as given by eq.(7 ) , is flat ( @xmath102 ) for either choice of the diffusive escape times in eq.(5 ) or eq.(6 ) . for @xmath0 collisions ,
the energy flux in @xmath17-decay gamma - rays is @xmath103 , where @xmath104 represents the differential cr energy flux .
since the neutrino flux is @xmath105 , the gamma - ray luminosity per unit energy resulted from the @xmath17-decay is related to the neutrino luminosity by @xmath106 thus the @xmath17-decay photon luminosity per unit energy of a single starburst should be @xmath107 for @xmath35 .
the @xmath0 process produces neutral pions @xmath17 and charged pions @xmath16 .
the neutral pion decay produces gamma - rays . besides
, @xmath19 pairs from the decay of @xmath16 , can also produce gamma - rays through ic scattering off the soft photons in the starburst region , mainly the infrared photons ( in competing with the synchrotron radiation in the magnetic field ) .
while the low - energy gamma - rays can escape and contribute to the diffuse gamma - ray background , the vhe gamma - rays will be absorbed due to the dense photon field in the starburst region .
the absorbed gamma - rays will be converted into @xmath19 pairs , which initiate cascades through interactions with the soft photons . as the vhe gamma - rays cascade down to enough low energies
, they can escape out of the starburst and also contribute to the diffuse gamma - ray background .
below we consider the separate contributions by the absorbed gamma - rays and the unabsorbed ones .
rapid star formation process makes an intense infrared photon field in the starburst .
the vhe gamma - ray photons may be absorbed by background photons and generate @xmath19 pairs .
the optical depth is @xmath108 , where @xmath109 is the cross section for pair - production @xcite and @xmath110 is the number density the infrared background photons .
we adopt the optical - infrared spectral energy models for the nuclei of starburst galaxies developed by and take arp 220 as a template for starbursts to calculate the absorption optical depth . using arp220 as
a template is because its infrared luminosity is close to luminosities of those starburst galaxies that contribute dominantly to the diffuse neutrino background ( see 4 ) .
we find that the absorption energy does not change too much if we use m82 as a template instead . for simplicity , we assume all starbursts have the same photon spectra as arp 220 . with such simplifications ,
the optical depth @xmath111 in a starbusrt depends only on its total infrared luminosity @xmath39 .
1 shows the corresponding absorption energy @xmath112 ( where @xmath113 ) as a function of the total infrared luminosity of starburst galaxies for different choices of @xmath114,@xmath53 and @xmath54 .
it can be seen that photons with energies above @xmath115 will be absorbed inside the starburst region .
the @xmath17 decay gamma - rays above @xmath112 will be absorbed in the soft photons in the starbursts and produce pairs , each carrying about half energy of the initial photons ( @xmath116 ) .
these pairs , together with the pairs resulted from @xmath16 decay , will cool through synchrotron and ic emission .
the synchrotron photon energy is @xmath117 , where @xmath118 is the energy of @xmath19 pairs and @xmath71 is the magnetic field in the starburst region . under reasonable assumptions about the magnetic field in the starburst region
, the synchrotron photon energy is below gev energies , so their contribution to the diffuse gamma - ray flux at @xmath25 gev is negligible .
note that the most constraining point of the gamma - ray background is around 100 gev , since the observed gamma - ray background flux decreases with the energy .
the ic photon energy is @xmath119 $ ] , where @xmath120 is the lorentz factor of the pair and @xmath121 is the energy of the soft background photons . approximating the soft photons as infrared photons with energy @xmath122 , the ic photons have energy of @xmath123 .
the ic photons above @xmath112 will be absorbed and an electro - magnetic cascade will be developed .
this cascade process transfers the energy of absorbed gamma - rays to lower and lower energies , until the secondary photons can escape from absorption .
the escaped gamma - ray photons can then contribute to the diffuse gamma - ray background . in order to calculate the fraction of the energy loss of @xmath19 pairs transferred to the cascade emission
, we need to know the energy loss fraction of @xmath19 through the ic emission .
energy loss timescales are crucial for assessing the fraction of energy loss in these two processes .
@xcite argued that in order for starburst galaxies to fall on the observed fir - radio correlation , the synchrotron cooling time in starbursts must be shorter than the ic cooling time and the escape time for relativistic electrons .
the reason is that , if this constraint is not satisfied , any variation in the ratio between the magnetic field and photon energy density ( @xmath124 ) would lead to large changes in the fraction of cosmic ray electron energy radiated via synchrotron radiation .
a linear fir - radio correlation would then require significant fine tuning .
the synchrotron timescale depends on the magnetic field in the starburst region .
the magnetic fields in starbursts are not well - understood and we parameterize the strength of the magnetic field in terms of the gas surface density @xmath125 with the following three scalings : + i ) first , in the assumption that the magnetic energy density equilibrates with the total hydrostatic pressure of the interstellar medium , @xmath126 @xcite , where @xmath127 is the gravitational constant .
fields strength as large as this equipartition are possible if the magnetic energy density equilibrates with the turbulent energy density of the ism . the measurements of zeeman splitting associated with oh megamasers for eight galaxies suggest that the magnetic energy density in the interstellar medium of starburst galaxies is indeed comparable to their hydrostatic gas pressure @xcite .
+ ii)@xmath128 is sometimes assumed , motivated by setting the magnetic energy density equal to the pressure in the ism produced by star formation ( @xmath129 ) . because of @xmath130 ( where @xmath131 is the star formation rate per unit area ) and the schmidt scaling law for star - formation @xmath132 @xcite , the scaling @xmath128 follows .
+ iii)the third is the minimum energy magnetic field case @xmath133 , which is obtained using the observed radio flux and assuming comparable cosmic - ray and magnetic energy densities @xcite .
although such a low magnetic field is not favored , as argued in various aspects @xcite , we keep this case in the calculation just to illustrate the difference when a low magnetic field strength is considerred .
+ thus , the strength of the magnetic fields can be summarized as @xcite @xmath134as the gas surface density @xmath135 scales with the surface density of star formation rate as @xmath136 and the star formation rate ( @xmath137 ) scales linearly with the total infrared luminosity @xmath138 , we get the relation ( assuming a constant star - formation radius @xmath51 ) @xmath139 the synchrotron energy loss timescale of @xmath140 is @xmath141 @xcite , while the ic energy loss timescale of relativistic @xmath140 , for a graybody approximation for the soft background photons , is given by @xcite @xmath142 where @xmath143 is the energy density of the soft photons , @xmath144 , @xmath145 is the temperature of the graybody radiation field and @xmath120 is the lorentz factor of @xmath146 .
note that eq.(14 ) applies to both the thomson scatterings and the scatterings in the klein - nishina regime when @xmath120 is very high . the fraction of the energy loss through synchrotron radiation is @xmath147 for one electron or positron of a particular energy . since this fraction is a function of the energy of @xmath19 ,
we integrate it over a proper energy range to estimate the fraction of the total energy loss of @xmath19 through synchrotron radiation in the energy range , which is @xmath148 where @xmath149 is used for the maximum energy of @xmath19 , corresponding to a maximum neutrino energy of @xmath150 .
we show , in fig.2 , this fraction for starburst galaxies with different @xmath138 .
the black , red and blue lines represent , respectively , the @xmath151 , @xmath152 and @xmath153 cases .
it shows that for both the @xmath151 and @xmath152 cases , the synchrotron loss constitute a fraction @xmath154 of the total energy loss .
there are two factors that leads to such a large synchrotron loss fraction : 1 ) the magnetic energy density is larger than the photon energy density in these cases ; 2 ) the klein - nishina effect for @xmath19 above @xmath155 @xcite causes the ic energy loss time to increase with @xmath120 , while the synchrotron loss time continues to fall as @xmath156 .
while the synchrotron loss energy goes into low - energy emission and thus does not contribute to the diffuse high - energy gamma - ray background , the ic loss energy will cascade down to the relevant energy range of the diffuse gamma - ray emission .
if the cascade develops sufficiently , the spectrum of the cascade emission has a nearly universal form of @xmath157 where @xmath112 is the absorption cutoff energy , @xmath158 is the break energy corresponding to @xmath159 , and @xmath160 typically .
the spectrum above @xmath112 decreases rapidly as @xmath161 .
the normalization of the cascade emission spectrum is determined by equating the total cascade energy with the total ic energy loss above @xmath112 , i.e. @xmath162 where @xmath163 is the energy of all @xmath17-decay gamma - rays above @xmath112 and the factor @xmath164 represents the sum contributions by the @xmath17-decay gamma - rays and the gamma - rays from ic scattering of @xmath165-decay @xmath140 , the latter of which has a flux about half of that of @xmath17-decay gamma - rays . the gamma - rays from @xmath17 decay with energies below @xmath112 will escape out of the starburst galaxies and contribute directly to the diffuse gamma - ray background .
this flux is model - independent and readily obtained from the observed neutrino flux by using eq.(10 ) . for a flat neutrino spectrum ,
the differential flux of @xmath17-decay gamma - rays below @xmath112 is @xmath166 .
as we pointed out before , the electrons and positrons accompanying with the neutrino production in the @xmath16 decay also contribute to the diffuse gamma - rays through ic scattering of soft background photons .
these @xmath19 pairs cool by both synchrotron and ic emission .
we denote the flux contributed by ic process with @xmath167 , which is important only when the magnetic energy density in the starburst region is low .
therefore the flux of the unabsorbed gamma - rays is @xmath168 adding the luminosity of the unabsorbed gamma - rays and that of the cascade gamma - rays , we get the total gamma - ray photon luminosity emitted from one starburst galaxy @xmath169
once the gamma - rays escape out of the starburst galaxy , they will further interact with the extragalactic infrared and microwave background photons , and similar cascades are formed for vhe gamma - rays . in this case , however , @xmath112 is different and dependent on the redshift distribution of starburst galaxies .
the cascade emission spectrum has the same form as equation ( 16 ) .
taking such cosmic cascades into consideration , the accumulated gamma - ray flux includes two parts , one is from the direct source contribution and the other is from the intergalactic cascades , i.e. @xmath170 where @xmath171 represents the direct source contribution by starburst galaxies and @xmath172 represents the flux from the intergalactic cascades .
the direct source contribution can be obtained by integrating the contributions of all starburst galaxies in the universe over their redshift and luminosity range , i.e. , @xmath173}{h_{0}\sqrt{(1+z)^{3}\omega _
{ m}+\omega _ { \lambda } } } dl_{\rm tir}dz , \ ] ] where @xmath174 = { l_{total}}[(1 + z){e_\gamma } ] { e^{-\tau ' _ { \gamma\gamma } ( { e_\gamma } , z)}}$ ] and @xmath175 is the absorption optical depth due to the extragalactic infrared and microwave background photons . the accumulated diffuse gamma - ray flux are shown in figures 3 - 5 for the cases of @xmath53 , @xmath114 and @xmath54 respectively .
it can be seen that , the diffuse gamma - ray flux in the case considering the synchrotron loss is less than half of that in the case neglecting the synchrotron loss .
this is because that the cascade component resulted from the absorbed gamma - rays is strongly suppressed due to the synchrotron radiation of the @xmath19 .
the accumulated diffuse gamma - ray flux after considering the synchrotron loss effect contributes @xmath176 of the observed diffuse gamma - ray background by fermi / lat at @xmath177 for both @xmath178 and @xmath128 cases .
for a steeper neutrino spectrum , since the energy fraction in absorbed gamma - rays above @xmath112 is lower , this effect is expected to be less important . as in @xcite
, we study the allowed range of the spectral index by the observed gamma - ray background data .
we find that the index must be @xmath179 , as shown in fig.6 , in order not to violate the observed gamma - ray background data by fermi / lat , which is in agreement with the results in @xcite .
we also study how much the starburst galaxies in different luminosity ranges and redshift ranges contribute to the diffuse gamma - ray background .
fig.7 shows the contributions in each luminosity range to the total flux .
it can be seen that most flux is contributed by the starbursts in the luminosity range from 10@xmath180 to 10@xmath181 @xmath182 . for starburst galaxies of such high luminosity ,
the pion production efficiency @xmath32 is close to 1 and these galaxies are proton calorimeters .
fig.8 shows the contributions by starburst galaxies in different redshift ranges to the total flux .
as expected , the dominant contribution is by starburst galaxies in the redshift range of @xmath183 .
starburst galaxies , which have many supernova or hypernova explosions , are proposed to be a possible source for the sub - pev / pev neutrinos recently detected by icecube @xcite .
we have shown that the minimum diffuse gamma - ray flux associated with these sub - pev / pev neutrinos is about @xmath184 , which is a factor of two lower than the case without considering the synchrotron loss of the @xmath185 pairs resulted from the absorption of very high energy photons .
this minimum diffuse gamma - ray flux constitute a fraction of @xmath176 of the observed gamma - ray background flux at @xmath25 gev energies , thus leaving a relatively large room for other sources to contribute to the gamma - ray background .
it was proposed that hypernovae remnants in starburst galaxies accelerate protons to @xmath186 @xcite , which then produce pev neutrinos via @xmath0 collisions with the dense surrounding medium @xcite .
remnants of normal supernovae may accelerate protons to pev energies , so they may not contribute to the @xmath187 tev neutrino flux , but they can produce @xmath188 tev gamma rays , thus contributing to the diffuse gamma - ray background as well .
but as long as the diffuse gamma - ray flux contributed by these normal supernovae does not exceed that contributed by the hypernova remnants too much , the total diffuse flux may still fall below the observed background
. it may be also possible that , if the remnants of normal supernovae produce a gamma - ray flux 3 - 4 times higher , the total gamma - ray flux from starburst galaxies can reach the level of the observed one .
interestingly , @xcite recently show that star - forming and starburst galaxies can explain the whole diffuse gamma - ray background in the 0.3 - 30 gev range .
we thank peter mszros , kohta murase and ruoyu liu for useful discussions , and the referee for the valuable report .
this work is supported by the 973 program under grant 2014cb845800 , the nsfc under grants 11273016 and 11033002 , and the excellent youth foundation of jiangsu province ( bk2012011 ) . | one attractive scenario for the excess of sub - pev / pev neutrinos recently reported by icecube is that they are produced by cosmic rays in starburst galaxies colliding with the dense interstellar medium .
these proton - proton ( @xmath0 ) collisions also produce high - energy gamma - rays , which finally contribute to the diffuse high - energy gamma - ray background .
we calculate the diffuse gamma - ray flux with a semi - analytic approach and consider that the very high energy gamma - rays will be absorbed in the galaxies and converted into electron - position pairs , which then lose almost all their energy through synchrotron radiation in the strong magnetic fields in the starburst region .
since the synchrotron emission goes into energies below gev , this synchrotron loss reduces the diffuse high - energy gamma - ray flux by a factor of about two , thus leaving more room for other sources to contribute to the gamma - ray background . for a @xmath1 neutrino spectrum ,
we find that the diffuse gamma - ray flux contributes about 20% of the observed diffuse gamma - ray background in the 100 gev range . however , for a steeper neutrino spectrum , this synchrotron loss effect is less important , since the energy fraction in absorbed gamma - rays becomes lower . |
Mums are now a flower of a different color. Japanese researchers have added a hint of clear sky to the humble plant’s palette, genetically engineering the first-ever “true blue” chrysanthemum.
“Obtaining blue-colored flowers is the Holy Grail for plant breeders,” says Mark Bridgen, a plant breeder at Cornell University. The results are “very exciting.”
Compounds called delphinidin-based anthocyanin pigments are responsible for the natural blues in such flowers as pansies and larkspur. Mums lack those compounds. Instead, the flowers come in a variety of other colors, evoking fiery sunsets, new-fallen snow and all things chartreuse.
In previous attempts to engineer a blue hue in chrysanthemums — and roses and carnations — researchers inserted the gene for a key enzyme that controls production of these compounds, causing them to accumulate. But ||||| Scientists genetically engineer the world’s first blue chrysanthemum
True blue flowers are a rarity in nature—they occur only in select species like morning glories and delphiniums. Now, researchers have created a genuinely blue chrysanthemum by adding two genes to the normally pink or reddish flower. The advance could be applied to other species—and it may mean that florists wanting to hawk blooms of blue will no longer have to dye them.
“This [advance] is of great impact,” says Toru Nakayama, a plant biochemist at Tohoku University in Sendai, Japan, who was not involved with the work. There are several popular commercial species for which no true blue varieties exist, he notes.
We all think we’ve seen blue flowers before. And in some cases, it’s true. But according to the Royal Horticultural Society’s color scale—the gold standard for flowers—most “blues” are really violet or purple. Florists and gardeners are forever on the lookout for new colors and varieties of plants, however, but making popular ornamental and cut flowers, like roses, vibrant blue has proved quite difficult. “We’ve all been trying to do this for a long time and it’s never worked perfectly,” says Thomas Colquhoun, a plant biotechnologist at the University of Florida in Gainesville who was not involved with the work.
True blue requires complex chemistry. Anthocyanins—pigment molecules in the petals, stem, and fruit—consist of rings that cause a flower to turn red, purple, or blue, depending on what sugars or other groups of atoms are attached. Conditions inside the plant cell also matter. So just transplanting an anthocyanin from a blue flower like a delphinium didn’t really work.
Naonobu Noda, a plant biologist at the National Agriculture and Food Research Organization in Tsukuba, Japan, tackled this problem by first putting a gene from a bluish flower called the Canterbury bell into a chrysanthemum. The gene’s protein modified the chrysanthemum’s anthocyanin to make the bloom appear purple instead of reddish. To get closer to blue, Noda and his colleagues then added a second gene, this one from the blue-flowering butterfly pea. This gene’s protein adds a sugar molecule to the anthocyanin. The scientists thought they would need to add a third gene, but the chrysanthemum flowers were blue with just the two genes, they report today in Science Advances .
“That allowed them to get the best blue they could obtain,” says Neil Anderson, a horticultural scientist at the University of Minnesota in St. Paul who was not involved with the work.
Chemical analyses showed that the blue color came about in just two steps because the chrysanthemums already had a colorless component that interacted with the modified anthocyanin to create the blue color. “It was a stroke of luck,” Colquhoun says. Until now, researchers had thought it would take many more genes to make a flower blue, Nakayama adds.
The next step for Noda and his colleagues is to make blue chrysanthemums that can’t reproduce and spread into the environment, making it possible to commercialize the transgenic flower. But that approach could spell trouble in some parts of the world. “As long as GMO [genetically modified organism] continues to be a problem in Europe, blue [flowers] face a difficult economic future,” predicts Ronald Koes, a plant molecular biologist at the University of Amsterdam who was not involved with the work. But others think this new blue flower will prevail. “It’s certainly an advance for the retail florist,” Anderson says. “It would have a lot of market value worldwide.”
As for Noda and other scientists, the blue blooms mean that at long last, they understand the biochemistry of this remarkable color. ||||| Naonobu Noda/NARO
Roses are red, but science could someday turn them blue. That’s one of the possible future applications of a technique researchers have used to genetically engineer blue chrysanthemums for the first time.
Chyrsanthemums come in an array of colours, including pink, yellow and red. But all it took to engineer the truly blue hue — and not a violet or bluish colour — was tinkering with two genes, scientists report in a study published on 26 July in Science Advances1. The team says that the approach could be applied to other commercially important flowers, including carnations and lilies.
“Consumers love novelty,” says Nick Albert, a plant biologist at the New Zealand Institute for Plant & Food Research in Palmerston North, New Zealand. And “people actively seek out plants with blue flowers to fill their gardens”.
Plenty of flowers are bluish, but it’s rare to find true blue in nature, says Naonobu Noda, a plant researcher at the National Agriculture and Food Research Organization near Tsukuba, Japan, and lead study author. Scientists, including Noda, have tried to artificially produce blue blooms for years: efforts that have often produced violet or bluish hues in flowers such as roses and carnations. Part of the problem is that naturally blue blossoming plants aren’t closely related enough to commercially important flowers for traditional methods — including selective breeding — to work.
Most truly blue blossoms overexpress genes that trigger the production of pigments called delphinidin-based anthocyanins. The trick to getting blue flowers in species that aren’t naturally that colour is inserting the right combination of genes into their genomes. Noda came close in a 2013 study2 when he and his colleagues found that adding a gene from a naturally blue Canterbury bells flower (Campanula medium) into the DNA of chrysanthemums (Chrysanthemum morifolium) produced a violet-hued bloom.
Getting the blues
Noda says he and his team expected that they would need to manipulate many more genes to get the blue chrysanthemum they produced in their latest study. But to their surprise, adding only one more borrowed gene from the naturally blue butterfly pea plant (Clitoria ternatea) was enough.
Anthocyanins can turn petals red, violet or blue, depending on the pigment’s structure. Noda and his colleagues found that genes from the Canterbury bells and butterfly pea altered the molecular structure of the anthocyanin in the chrysanthemum. When the modified pigments interacted with compounds called flavone glucosides, the resulting chrysanthemum flowers were blue. The team tested the wavelengths given off by their blossoms in several ways to ensure that the flowers were truly blue.
The quest for blue blooms wouldn't only be applicable to the commercial flower market. Studying how these pigments work could also lead to the sustainable manufacture of artificial pigments, says Silvia Vignolini, a physicist at the University of Cambridge, UK, who has studied the molecular structure of the intensely blue marble berry.
Regardless, producing truly blue flowers “is a great achievement and demonstrates that the underlying chemistry required to achieve 'blue' is complex and remains to be fully understood”, says Albert. ||||| PHOTOS: Japanese Scientists Turn Chrysanthemums 'True Blue'
Enlarge this image toggle caption Naonobu Noda/NARO Naonobu Noda/NARO
Japanese scientists have genetically engineered a chrysanthemum flower that is "true blue" — a color that has long eluded flower breeders and researchers.
Blue has proved a challenge to produce in many other popular flowers, including roses, carnations and lilies.
It hasn't happened until now in chrysanthemums due to the "recalcitrant and unpredictable expression of introduced genes," Naonobu Noda from Japan's National Agriculture and Food Research Organization tells The Two-Way. Noda is the lead author of the paper released today in Science Advances.
When scientists tried previously to introduce genes to create a blue color, Noda said, the flower would "shut them off by as yet unknown mechanisms." Other attempts produced violet flowers, not blue ones.
The researchers then took genes from two very blue flowers — butterfly peas and Canterbury bells — and snuck them into the chrysanthemum.
toggle caption Wikimedia Commons
Those two genes modified the chrysanthemums' natural pigment to create a colorful molecule called delphinidin.
(Interestingly, delphinidin is also found in Cabernet Sauvignon grapes).
The scientists said the petals only turned a brilliant "true blue" due to an interaction between the delphinidin and the chrysanthemum's other, colorless compounds.
How do you define "true blue"? The Royal Horticultural Society has strict parameters, as defined by its color charts:
toggle caption Naonobu Noda/NARO
Noda says that this is a simpler process than they were expecting to have pigments express blue coloration, and adds that the technique might be applicable to other flowers, like roses and lilies.
Chrysanthemums are the most popular flower in Japan, according to The Associated Press. Here's more from the wire service:
"Like the cherry blossom, the chrysanthemum, called 'kiku' in Japanese, symbolizes the season, but more than that, it's a symbol of the country itself. The monarchy is referred to as the Chrysanthemum Throne and the imperial crest is a stylized mum blossom. That seal is embossed on Japanese passports. The flower is also a common motif in art, and it's seen in everyday life depicted on the 50-yen coin."
However, don't expect to see blue mums in stores soon. Noda says they have no specific plans for their sale, adding that "as they are genetically modified organisms, it is not easy to commercialize." ||||| Abstract Various colored cultivars of ornamental flowers have been bred by hybridization and mutation breeding; however, the generation of blue flowers for major cut flower plants, such as roses, chrysanthemums, and carnations, has not been achieved by conventional breeding or genetic engineering. Most blue-hued flowers contain delphinidin-based anthocyanins; therefore, delphinidin-producing carnation, rose, and chrysanthemum flowers have been generated by overexpression of the gene encoding flavonoid 3′,5′-hydroxylase (F3′5′H), the key enzyme for delphinidin biosynthesis. Even so, the flowers are purple/violet rather than blue. To generate true blue flowers, blue pigments, such as polyacylated anthocyanins and metal complexes, must be introduced by metabolic engineering; however, introducing and controlling multiple transgenes in plants are complicated processes. We succeeded in generating blue chrysanthemum flowers by introduction of butterfly pea UDP (uridine diphosphate)–glucose:anthocyanin 3′,5′-O-glucosyltransferase gene, in addition to the expression of the Canterbury bells F3′5′H. Newly synthesized 3′,5′-diglucosylated delphinidin-based anthocyanins exhibited a violet color under the weakly acidic pH conditions of flower petal juice and showed a blue color only through intermolecular association, termed “copigmentation,” with flavone glucosides in planta. Thus, we achieved the development of blue color by a two-step modification of the anthocyanin structure. This simple method is a promising approach to generate blue flowers in various ornamental plants by metabolic engineering.
INTRODUCTION Flower color is one of the most important breeding targets for ornamental plants because it has a great influence on customer choice in buying potted flowers, garden flowers, and cut flowers. Rose, chrysanthemum, carnation, lily, and gerbera are major ornamental plants in terms of both value and production yields in the global cut flower market. Although white, yellow, orange, red, magenta, and green variants of these flowers have been domesticated from wild species and bred by mutation breeding and interspecific hybridization, violet or blue flowers have not been produced by conventional breeding methods. Hence, this goal is of particular interest both to the floricultural industry and in the field of horticultural and plant sciences. In general, anthocyanin pigments contribute to the development of red, purple, and blue flower colors. The B-ring hydroxylation and methylation patterns of anthocyanins contribute to the development of flower color. The abovementioned cut flower plants have cyanidin-based anthocyanins with two hydroxyl groups at the 3′ and 4′ positions on the B-ring, which are responsible for reddish coloration. Because these flowers lack flavonoid 3′,5′-hydroxylase (F3′5′H) activity, they do not synthesize delphinidin-based anthocyanins, which have an additional hydroxyl group at the 5′ position and are responsible for the bluish coloration in many plants (1). The cytochrome P450 enzyme F3′5′H controls the biosynthesis of delphinidin-based anthocyanins (1). Recently, the F3′5′H was introduced into rose and carnation plants, and the resulting genetic transformants produced novel violet flowers that accumulate delphinidin-based anthocyanins (2–5). We also introduced Canterbury bells (Campanula medium) F3′5′H into chrysanthemum. The coloration of these transgenic chrysanthemum plants became bluer, but the flowers were still limited to purple/violet (6, 7). An accumulation of delphinidin-based anthocyanins is necessary to develop purple/violet color but not sufficient to produce a true blue color. The blue color development of flowers has been well studied, and several mechanisms have been described. These include intramolecular associations within anthocyanin via attached glycosyl and aromatic acyl groups (8, 9), intermolecular associations of anthocyanin with copigment compounds such as aromatic acid derivatives and flavonoids (8, 10), metal complex formation with anthocyanin and flavonoid (8, 11, 12), and modification of vacuolar pH to higher values (8, 13, 14). Because modification of vacuolar pH and metal ion transportation might disturb cellular homeostasis, we initially proceeded by modification of anthocyanin with sugar and aromatic acyl groups to facilitate intramolecular associations. The major anthocyanins of natural chrysanthemums are cyanidin 3-O-(6″-O-malonyl)glucoside (A1) (15) and cyanidin 3-O-(3″,6″-di-O-malonyl)glucoside (A2) (16), whereas those of purple/violet transgenic chrysanthemums are their delphinidin analogs (A5 and A6) (Fig. 1 and fig. S1) (6). Delphinidin 3-O-(6″-O-malonyl)glucoside-3′,5′-di-O-(6‴,6‴′-di-O-p-coumaroyl)glucoside (ternatin D3) is one of the simplest polyacylated anthocyanins responsible for the blue coloration of Clitoria ternatea (butterfly pea) (fig. S1) (17). In transgenic chrysanthemums, ternatin D3 is likely to be the least-modified blue anthocyanin. Therefore, we tried to synthesize ternatin D3 in chrysanthemums by hydroxylation at the 3′ and 5′ positions and by attachment of p-coumaroyl-glucosyl moieties at these hydroxyl groups. In the process of examining this transformation, we unexpectedly generated blue flower plants by means of glucosylation without aromatic acylation. We then studied the mechanism of blue coloration by analyzing newly synthesized anthocyanins and their intermolecular associations in chrysanthemum petals. Fig. 1 Scheme for introducing 3′,5′-hydroxylation and 3′,5′-glucosylation into the anthocyanin biosynthetic pathway in chrysanthemum petals. The major anthocyanin of ‘Taihei’ wild-type chrysanthemum was cyanidin-based anthocyanin (A1). F3'5'H, flavonoid 3',5-hydroxylase; A3′5′GT, UDP-glucose:anthocyanin 3′,5′-O-glucosyltransferase.
RESULTS Blue coloration in transgenic chrysanthemums First, we introduced the butterfly pea gene CtA3′5′GT encoding UDP (uridine diphosphate)–glucose:anthocyanin 3′,5′-glucosyltransferase (18) into chrysanthemums by using binary vector pB249 (Fig. 1 and fig. S2). Although transgenic plants expressing CtA3′5′GT were obtained, their flowers did not show a color change to bluish hue (table S1). Next, to achieve hydroxylation and glucosylation of the B-ring of anthocyanin in chrysanthemums, we used the binary vector pB423 to coexpress the Canterbury bells gene F3′5′H (CamF3′5′H) and the gene CtA3′5′GT (Fig. 1 and fig. S2). Both transgenes were expressed under the control of the chrysanthemum F3H promoter. We also designed vector pB428 containing a chrysanthemum F3′H RNA interference (RNAi) construct (7, 19) to reduce the accumulation of red cyanidin derivatives, in addition to the CamF3′5′H and CtA3′5′GT cassettes (fig. S2 and table S1), and used this vector for transformation. As a result, 19 of 32 (59%) transgenic ‘Taihei’ chrysanthemum lines harboring the simpler pB423 construct changed their flower color to a blue hue within the blue or violet-blue color groups of the Royal Horticultural Society (RHS) Colour Charts (Fig. 2A and table S1). Fig. 2 Anthocyanins derived from ray florets of blue-colored transgenic chrysanthemums. (A) High-performance LC (HPLC) chromatograms of anthocyanins in blue petal extracts detected at 530 nm. (B) Ultraviolet (UV)–visible absorption spectra of A7 and A8 recorded during online HPLC under acidic conditions. An additional spectral maximum at around 320 nm was not detected in either, indicating a lack of aromatic acyl groups. (C) Chemical structures and MS/MS fragmentation spectra of A7 and A8. The product ions of A7 at m/z = 789 [M]+ were 627 (−Glc), 465 (−2 × Glc), and 303 (−3 × Glc). The product ions of A8 at m/z = 875 [M]+ were 713 (−Glc), 627 (−Glc, −Mal), 465 (−2 × Glc, −Mal), and 303 (−3 × Glc, −Mal; delphinidin aglycone). Dotted arrows show the proposed fragmentation scheme. Glc, glucosyl; Mal, malonyl; A7, delphinidin 3,3′,5′-tri-O-glucoside (preternatin C5); A8, delphinidin 3-O-(6″-O-malonyl)glucoside-3′,5′-di-O-glucoside (ternatin C5). Anthocyanin structures in blue chrysanthemums The blue ray florets of transgenic chrysanthemums mainly contained anthocyanins A7 and A8 and minor anthocyanin A3 (Fig. 2A and fig. S1). The absorbance spectra indicated the absence of an aromatic acyl moiety in these anthocyanin structures (Fig. 2B). We analyzed A8 in the extracts of blue ray florets by liquid chromatography–photodiode array–mass spectrometry (LC-PDA-MS) and detected a molecular ion at mass/charge ratio (m/z) = 875 [M]+ corresponding to malonylated delphinidin triglucoside (Fig. 2C). We identified the structure of A8 as delphinidin 3-O-(6″-O-malonyl)glucoside-3′,5′-di-O-glucoside (ternatin C5) (Fig. 2) (17) by further analyses of LC-MS, 1H nuclear magnetic resonance (NMR), and nuclear Overhauser effect spectroscopy (NOESY) spectra and high-resolution MS (Supplementary Materials and Methods). Partial hydrolysis of A8 produced A7, which was confirmed by coelution with authentic standard in HPLC. LC-MS analysis yielded the molecular ion of A7 at m/z = 789 [M]+ and product ions corresponding to the loss of the glucosyl moiety from A7. These results suggested that the A7 structure was delphinidin 3,3′,5′-tri-O-glucoside (preternatin C5) (17, 18). From the spectral data of LC-MS (m/z = 697 [M]+), high-resolution MS, and 1H NMR, we determined the minor anthocyanin A3 structure to be cyanidin 3-O-(6″-O-malonyl)glucoside-3′-O-glucoside (Fig. 1). All these anthocyanins were glucosylated at the 3′- and/or 5′-hydroxyl groups (Supplementary Materials and Methods). Coloration, anthocyanin composition, and transgene expression We obtained various colored transgenic ‘Sei Arabella’ chrysanthemums carrying CamF3′5′H and CtA3′5′GT. Using these plants, we analyzed the relationship among coloration, anthocyanin composition, and transgene expression (Figs. 3 and 4). Most transgenic lines with flowers in the blue/violet-blue group were distributed below a hue angle of 290°. Almost all lines had shifted from the red-purple group of wild type to the blue/violet-blue group (Fig. 3). Fig. 3 Flower color distribution of transgenic ‘Sei Arabella’. Hue of flower color was evaluated by hue angle (H°), where H° near 270 shows blue color, H° from 300 to 340 shows violet to purple color, and H° over 340 shows red color. Chroma value describes the color strength. The color names given in parentheses are color groups according to the RHS Colour Charts. Circles, wild-type ‘Sei Arabella’; diamonds, transgenic lines. Fig. 4 Flower coloration, anthocyanin composition, and transgene expression in transgenic ‘Sei Arabella’. (A) Pictures of representative flower colors of wild-type and transgenic lines. Each line presents the color group and number of RHS Colour Charts. (B) Anthocyanin composition. (C and D) Relative expression of CamF3′5′H (C) and the resultant delphinidin-based anthocyanins (D). Contents of delphinidin-based anthocyanins corresponded well with the expression of CamF3′5′H. (E and F) Relative expression of CtA3′5′GT (E) and the resultant 3′/3′,5′-glucosylated anthocyanins (F). Contents of 3′/3′,5′-glucosylated anthocyanins corresponded well with the expression of CtA3′5′GT. (G) Visible absorption spectra of fresh petals of wild-type (pink), 1916-10 (purple), and 1916-23 (blue) lines. (H) Visible absorption spectra of major anthocyanins derived from pink (A1; wild type), purple-violet (A5), and blue/violet-blue (A8) chrysanthemums in acetate buffer (pH 5.6). The flowers of wild-type plants accumulated non–3′-glucosylated cyanidin-based anthocyanins (A1 and A2) and exhibited a pink color (Fig. 4, A and B, and fig. S3). The flower color of transgenic 1916-10 plants, which accumulated non–3′/3′,5′-glucosylated delphinidin-based anthocyanins (A5 and A6), exhibited a purple color. On the other hand, the purplish pink flowers of transgenic 1916-25 plants mainly accumulated 3′-glucosylated cyanidin-based anthocyanin (A3). In contrast, the flowers of 1916-18, 1916-12, and 1916-23 lines, which accumulated 3′,5′-glucosylated delphinidin-based anthocyanins (A7 to A9), were blue (Fig. 4, A and B, and fig. S3). We also detected flavone glucosides and caffeoylquinates in ray florets of wild-type and transgenic lines. The composition of these analytes was almost the same in the different flower colored lines (fig. S4). The blue coloration was dependent on the composition ratio of the 3′,5′-glucosylated delphinidin-based anthocyanins (Fig. 4, A and B). We verified the expression of the transgenes in ray florets by quantitative real-time polymerase chain reaction (qRT-PCR) assay. In purple flower colored lines, transgenic 1916-10 plants expressed only CamF3′5′H, whereas transgenic 1916-25 plants expressed CtA3′5′GT with a low level of CamF3′5′H. The violet/blue transgenic lines 1916-18, 1916-12, and 1916-23 expressed both CamF3′5′H and CtA3′5′GT. The content of the delphinidin-based anthocyanins correlated with the relative expression of CamF3′5′H, whereas the content of the 3′- and/or 5′-glucosylated anthocyanins correlated with the relative expression of CtA3′5′GT (Fig. 4, C to F). These results indicated that CtA3′5′GT efficiently glycosylated both cyanidin- and delphinidin-based anthocyanins in transgenic chrysanthemums. As mentioned above, the content of flavone glucosides and caffeoylquinates, which are candidates for copigments (8, 10), was almost the same among the wild-type and transgenic lines (fig. S4). In addition, expression of CamF3′5′H led to the production of some new flavonoids, such as C2 (fig. S4, B to E). Spectra of major anthocyanins and intact ray florets The intact pink-colored petals of host ‘Sei Arabella’ exhibited a visible absorbance spectrum, with the peak of the maximum wavelength of visible absorption (λ vismax ) at 556 nm. The spectrum of the purple-violet petals of transgenic chrysanthemums was shifted to longer wavelengths, with the λ vismax at 561 nm. The blue petals showed a characteristic spectrum with a longer wavelength, with the λ vismax at 573 nm, and a second absorption maximum called a shoulder at around 615 nm (Fig. 4G). The major anthocyanins of pink-colored wild-type plants, purple-violet–colored transgenic lines, and blue-colored lines were A1 and A2, A5 and A6, and A7 and A8, respectively (Fig. 4B and table S2). In the acidic solution of the HPLC solvent, A1 had a λ vismax at 518 nm. The λ vismax of A5 shifted toward a longer wavelength at 527 nm, whereas that of A8 shifted toward a shorter wavelength at 511 nm (Fig. 2B). In acetate buffer solution at pH 5.6 corresponding to the pH of the petal juice, the λ vismax of the A1, A5, and A8 absorption spectra was 533 nm, 535 nm (with a shoulder at 565 nm), and 561 nm (with a shoulder at 590 nm), respectively (Fig. 4H), with successively longer wavelength shifts. Even in solution at the pH of the petals, the λ vismax of each major anthocyanin was shorter than its corresponding value for intact petals (Fig. 4, G and H). These results suggested that the flower color of chrysanthemums arises from intermolecular copigmentation of the major anthocyanin with another compound in the petals. Identification of copigments for blue coloration We attempted to identify the copigment counterpart of major anthocyanin A8 responsible for generating the blue flower coloration of transgenic chrysanthemums by analyzing an extract from the blue petals of the ‘Taihei’ transgenic chrysanthemum using a cross–thin-layer chromatography (cross-TLC) method (20). After the development of the TLC plate, red, violet, and blue regions were visible in the anthocyanin development lines (Fig. 5A). Observation under UV light irradiation showed that the blue and violet regions crossed with a yellow fluorescent band (X) and an invisible band (Y), respectively (Fig. 5B). These results suggested that bands X and Y contained copigments that shifted the red coloration of anthocyanin A8 to a more bluish coloration. Fig. 5 Copigments responsible for blue coloration associated with anthocyanin. (A and B) Developed TLC plate observed under fluorescent light (A) and UV light (365 nm) (B). Blue arrows indicate blue color parts on the anthocyanin bands overlapping with band X, which showed yellow fluorescence under UV light. Purple arrows indicate violet color parts overlapping with band Y, which was invisible under fluorescent and UV light. Broken lines indicate regions recovered for LC-MS analyses. (C to E) HPLC chromatograms of extracts from the cellulose TLC plate of band X (C) and band Y (D) and of the blue petal extract (E) monitored by absorption at 360 nm for flavonoids. C1 and C1′ were major compounds detected in band X. C2 and C2′ were major compounds detected in band Y. (F and G) Structures of C1 (F) and C2 (G). Arrows indicate heteronuclear multiple-bond coherence. C1′ and C2′ were identified as demalonyl derivatives of C1 and C2, respectively. We extracted compounds contained in bands X and Y from the cellulose TLC plate. The two major peaks detected in the band X extract were assigned as C1 and C1′, and those in band Y were assigned as C2 and C2′ (Fig. 5, C and D). We analyzed these compounds by LC–PDA–MS analysis: λ max peaks in the UV-visible spectrum were observed at 345, 268, and 236 nm for C1 and at 351, 269, and 235 nm for C2, and their molecular ions ([M + H]+) were determined as m/z = 535 for C1 and 551 for C2 (Fig. 5, C to E, and figs. S4 and S5). We purified these compounds from blue ray florets (Fig. 5E) and identified their structures. C1 and C2 were identified as luteolin 7-O-(6″-O-malonyl)glucoside (21, 22) and tricetin 7-O-(6″-O-malonyl)glucoside, respectively, by high-resolution MS analysis and a series of NMR experiments [1H NMR, 13C NMR, heteronuclear multiple-bond correlation (HMBC), and heteronuclear multiple-quantum coherence (HMQC)] (see Fig. 5, F and G, and Supplementary Materials and Methods). The molecular ions of C1′ and C2′ corresponded to the demalonylated derivatives of C1 and C2, respectively, and thus were identified as luteolin 7-O-glucoside and tricetin 7-O-glucoside, respectively (fig. S5). In vitro reconstruction of blue flower color The molar ratio of sum of the 3′,5′-diglucosylated anthocyanins (A7, A8, and A9), C1, and C2 in the ray florets of chrysanthemums was 1:1.7:0.4 on average. The ratio of total flavones to total anthocyanins was approximately 5:1 (table S2). On the basis of the compound ratio, we performed copigmentation experiments in acetate buffer (pH 5.6) to approximate the pH of the ‘Taihei’ chrysanthemum petal juice. Increasing the concentration of C1 in A8 assay solution led to increased absorption (known as a hyperchromic shift) and a longer wavelength shift (known as a bathochromic shift) of λ vismax , with a shoulder peak at around 600 nm (Fig. 6A). On the addition of five or more equivalents of C1 to A8, the color of the buffer solution turned from violet to blue owing to the bathochromic shift (Fig. 6, A and D). The λ vismax peak shifted from 560 to 570 nm, and the shoulder region shifted from 590 to around 610 nm, yielding an absorption spectrum similar to that of intact blue petals (Figs. 4G and 6, A and H). Fig. 6 In vitro reconstruction of petal color by mixing isolated components. Anthocyanin and copigment were mixed in acetate buffer (pH 5.6). (A) Visible absorption spectra of A8 and its mixture with C1. (B) Visible absorption spectra of A5 and its mixture with C1. (C) Visible absorption spectra of A1 and its mixture with C1. (D) Color of A8 solution (left) and its mixture with C1 (1:10) (right). (E) Color of A5 solution (left) and its mixture with C1 (1:10) (right). (F) Visible absorption spectrum of mixture of A7 or A8 with various flavone glycosides (C1, C2, C1′, and F1′). (G) Visible absorption spectra of a mixture of A8, C1 and C2 solution and its mixture with Fe3+ or Mg2+ ion. (H) Summary of bathochromic shifts and hyperchromic shifts by A8, A5, and A1 solutions by mixing with C1 (1:5). A8, ternatin C5; A5, delphinidin 3-O-(6′′-O-malonyl)glucoside; A1, cyanidin 3-O-(6″-O-malonyl)glucoside; C1, luteolin 7-O-(6″-O-malonyl)glucoside; C2, tricetin 7-O-(6″-O-malonyl)glucoside; C1′, flavone 7-O-glucoside; F1′, apigenin 7-O-glucoside. Addition of C1 to A5 led to an increase in absorbance at around 565 nm and resulted in the same absorption spectrum as that of intact petals of purple-violet chrysanthemums (Figs. 4G and 6, B and E). Moreover, addition of C1 to A1 also led to an increase in absorbance at around 540 to 550 nm and a longer wavelength shift of the λ vismax (Fig. 6C). Overall, we observed longer wavelength shifts of the λ vismax and shoulder peaks because of copigmentation following the addition of C1 to A1, A5, and A8. In addition, we confirmed the copigmentation effect of C2, C1′, and apigenin 7-O-glucoside (F1′) on A8 (Fig. 6F). Because metal ions such as Mg2+ or Fe3+ are often involved in blue flower color development (8, 11, 12), we investigated whether these ions are involved in the blue chrysanthemum coloration. However, we did not observe spectral changes on the addition of Mg2+ or Fe3+ ions to the A8, C1, and C2 mixtures (Fig. 6G). We observed a bathochromic shift of λ vismax and shoulder peaks due to copigmentation with C1 for all tested anthocyanins, whereas the largest shift of λ vismax and the shoulder was Δ15 and Δ13 nm for A5 and A8, respectively (Fig. 6H). We observed the effect of copigmentation with C1 for three anthocyanins that have differences in the B-ring structure. Whereas the hyperchromic shift was observed equally among the anthocyanins for the λ vismax and shoulder peaks, the bathochromic shift showed a differential effect. The bathochromic shift of λ vismax was stronger for A5 than for A8. Thus, the blue coloration of A8 is associated with the bathochromic shift of the shoulder peak of absorption at 590 nm rather than the λ vismax peak.
DISCUSSION Here, we have generated true blue-colored chrysanthemums by introducing only two genes, CamF3′5′H and CtA3′5′GT. Although we also introduced an F3′H RNAi construct to down-regulate the production of red cyanidin derivatives (7, 19), this construct was not essential for the generation of blue flowers. Among all genetically engineered flowers reported to date (9), these transgenic chrysanthemums have produced the most blue-shifted flowers. The blue coloration was dependent on both the coexpression of CamF3′5′H and CtA3′5′GT and the resulting accumulation of 3′,5′-glucosylated delphinidin-based anthocyanins, which do not have aromatic acyl moieties (Fig. 4, A and B). This finding has not been previously reported. This result was unexpected because it has been previously understood that glycosylation on the 3′- and 5′-hydroxyl groups of anthocyanins is responsible for red coloration in flowers (23–26). For example, 3′,5′-diglucosylated delphinidin galactosides, obtained from berries of the Siberian dogwood Cornus alba ‘Sibirica,’ have absorption spectra with a λ vismax peak at a shorter wavelength than their non–3′,5′-glucosylated analogs under acidic conditions (26, 27). Similar results were obtained in this study; under acidic conditions, 3′,5′-glucosylated delphinidin 3-malonylglucoside (A8) had an absorption spectrum having a λ vismax peak at a shorter wavelength than both its non–3′,5′-glucosylated analog (A5) and the cyanidin-based analog (A1). Hence, this finding prompted us to examine the mechanisms of blue coloration in the transgenic chrysanthemums. The coloration of anthocyanins changes under various pH conditions. We therefore analyzed the absorption spectra of the principal accumulated anthocyanins under a weakly acidic condition (pH 5.6), regarded as the pH of the juice from ray floret tissues containing blue-pigmented vacuoles. Under this condition, A8 solution had a λ vismax peak at a longer wavelength and showed a bluer coloration than the A5 solution (Figs. 4H and 6). This result indicates that 3′,5′-glucosylation of delphinidin-based anthocyanins produces a more bluish color in planta. Nevertheless, the absorption spectrum of the blue ray florets had λ vismax and shoulder peaks at a much longer wavelength than the A8 solution (Fig. 4, G and H). This suggests that, besides the violet coloration under weakly acidic conditions, there is an additional mechanism concerned with blue color development. One assumed mechanism of blue coloration is the intramolecular association of polyacylated anthocyanins, in which a hydrophobic stacking structure is formed between aromatic acyl moieties and the anthocyanidin chromophore (8, 9). However, anthocyanins without aromatic acyl moieties, such as A8, cannot form any such interaction by themselves. We therefore considered the possibility of intermolecular associations of the 3′,5′-diglucosylated anthocyanins with copigments (8, 10). Shimizu-Yumoto et al. (20) developed the cross-TLC method, which can comprehensively detect copigments in a sample loaded on the TLC plate based on coloration changes in the development line of anthocyanins caused by overlap with development lines of copigments. We therefore applied the cross-TLC method to detect copigments in the extract of the blue ray florets of transgenic chrysanthemums. Consequently, C1 and C2 compounds were detected as copigment candidates (Fig. 5). These candidate copigment compounds were determined to be the major flavone luteolin 7-O-(6″-O-malonyl)glucoside (C1) and the minor tricetin 7-O-(6″-O-malonyl)glucoside (C2). When A8 was added to the C1 solution at pH 5.6, the λ vismax and shoulder peaks shifted to a longer wavelength and showed a bluer color than A8 solution without C1. A spectral pattern similar to that of blue ray florets was regenerated when C1 was mixed with A8 at a ratio of 5:1. C1 had a similar copigmentation effect on A7 (Fig. 6F). C2 also had the same effect on A8. We also detected other major flavones, apigenin 7-O-(6″-O-malonyl)glucoside (F1) and acacetin 7-O-(6″-O-malonyl)glucoside (F2) in the petals (table S2). The demalonyl analog of F1, apigenin 7-O-glucoside, and the demalonyl analog of C1, luteolin 7-O-glucoside, also had a copigmentation effect in vitro (Fig. 6F). Because a malonyl moiety is not involved in copigmentation, F1 is likely to contribute to the blue coloration as a copigment in planta. However, we did not detect a clear copigmentation effect of F1 by the cross-TLC method. In this case, we assumed that the crossing positions of the anthocyanin and F1 overlapped with those of C1 and C2 and showed a violet or blue color (Fig. 5). The molar ratio of flavones to anthocyanins in ray florets of blue chrysanthemum lines was distributed between 2.2 and 10.4. The content of flavone glucosides as copigments is thought to be sufficient for blue coloration by association with anthocyanin molecules in the ray florets of transgenic chrysanthemums. We believe that caffeoylquinates are not copigments involved in blue pigmentation in planta because they accumulate separately from anthocyanins, which are present in epidermal cells (fig. S6). Metal ions are involved in intermolecular associations leading to blue flower color development in some blue flowers (10–12). We therefore investigated whether the spectrum of the 3′,5′-diglucosylated anthocyanin and flavone mixture was altered by the addition of Fe3+ or Mg2+ ions. However, neither a spectral change nor an effect on blue color development was observed (Fig. 6G). We conclude that the blue flower color of chrysanthemum is mainly due to an intermolecular association between 3′,5′-diglucosylated delphinidins and flavone 7-glucoside derivatives. Flavone 7-glycoside derivatives have been reported as copigments associated with delphinidin-based anthocyanins or its 3′- and/or 5′-methoxylated derivatives to produce blue or violet coloration in the flower petals of lupin (Lupinus sp.) (28) and torenia (Torenia fournieri) (29). The 3′- and/or 4′-hydroxyflavone 7-glycosides including C1 are major flavonoids in wild-type chrysanthemums, whereas C2, which is further hydroxylated at the 5′ position of the B-ring, is undetectable. C2 is synthesized owing to the expression of the introduced CamF3′5′H gene. We also reconstructed the UV-visible absorption spectrum of purple/violet-colored chrysanthemums and that of the pink-colored chrysanthemums in vitro by mixing C1 and A5 and by mixing C1 and A1, respectively (Figs. 4G and 6, B and C). Flavone 7-glycoside derivatives are also involved as copigments in both the purple/violet and pink coloration of transgenic and wild-type chrysanthemum flowers, respectively. The bathochromic shift for blue coloration is caused both by the hydroxylation and glucosylation of the anthocyanin B-ring and by copigmentation with flavone glucoside (Fig. 6H). An anthocyanin molecule can alter its structure from a flavylium ion structure showing a red color to a quinonoidal base structure showing a purple color and successively to an anionic quinonoidal base structure showing a blue color (8, 10). Copigments can alter this structural equilibrium through hydrophobic stacking interactions with the anthocyanin molecule. A5 seems to be present as the flavylium ion (λ vismax = ca. 530 nm) and the quinonoidal base (λ vismax = ca. 570 nm) structures in solution at pH 5.6, whereas A8 seems to be present as the quinonoidal base and/or the anionic quinonoidal base (λ vismax = ca. 570 and ca. 610 nm) (Fig. 6). We consider that the coloration and spectral change caused by the addition of copigment C1 are due to a change in this equilibrium: The proportion of the quinonoidal base structure increased for A5, whereas that of the anionic quinonoidal base structure increased for A8. Previously reported structures of blue flower pigments, such as polyacylated anthocyanins and metalloanthocyanins (8, 9), are too complex to be realized by metabolic engineering because the fine manipulation of multiple transgenes would be necessary. In our case, only two transgenes, namely, CamF3′5′H and CtA3′5′GT, were enough to generate blue chrysanthemums: The 3′,5′-diglucosylated delphinidin exhibits a blue color by intermolecular association with flavone glucosides under the weakly acidic pH conditions of general flower petals. The flavone glycosides are naturally occurring flavonoids in a wide variety of plant species; hence, this two-step modification of anthocyanin structure by B-ring hydroxylation and glucosylation is a highly promising approach to generating blue-colored flowers, which overcomes the problems arising from the introduction and regulation of multiple genes.
MATERIALS AND METHODS Plant materials Chrysanthemum morifolium ‘Taihei’ (disbud type), ‘Sei Arabella’ (decorative type), ‘Sei Shawl’ (decorative type), 940-0765 (formerly 94-765; disbud type), T27 (small-flowered pompons type), T37 (small-flowered pompons type), and T57 (decorative type) were used for the host in transformation experiments (table S1). They were cultivated in vitro and maintained as previously described (6). Plant transformation and cultivation Binary vectors were introduced into the Agrobacterium tumefaciens strain EHA105 (30), and chrysanthemum leaf explants from in vitro propagation were used for transformation, as previously described (6). Transgenic plants were transferred to soil and grown for 1 month under long-day treatment via exposure to 4-hour night-break illuminations; short-day flowering was then induced by exposure to 11-hour day length in a glasshouse for genetically modified plants. After collection, petals were frozen in liquid nitrogen and stored at −80°C until further analysis. Construction of transgenes We constructed the three binary vectors (pB423, pB428, and pB249) in fig. S2 and table S1 in accordance with a previously reported protocol (6, 31), with partial modification as described in Supplementary Materials and Methods. All gene expression cassettes were constructed in the pBI121 vector. Canterbury bells (C. medium) F3′5′H (CamF3′5′H; GenBank accession number FW570877) and butterfly pea (C. ternatea) A3′5′GT (CtA3′5′GT, UGT78K8; GenBank accession number AB115560) were expressed by using the CmF3H promoter (GenBank accession number FW570860), Arabidopsis heat shock protein 18.2 gene terminator (32), Agrobacterium NOS terminator, and NtADH-5′ untranslated region (5′UTR) as a translational enhancer (33). The RNAi cassette for down-regulation of CmF3′H was expressed under the control of the CmF3H promoter and Agrobacterium NOS terminator in pB428. We obtained the RNAi trigger sequence of CmF3′H by PCR amplification and the Gateway LR reaction with the pANDA35K vector (34). The primer sets used in vector construction are listed in table S3. qRT-PCR analysis Total RNA was extracted from petals of chrysanthemums by using TRIzol Reagent (Thermo Fisher Scientific) and the PureLink RNA Mini Kit (Thermo Fisher Scientific) and then treated with the PureLink DNase Set (Thermo Fisher Scientific), in accordance with the manufacturer’s instructions. First-strand complementary DNAs (cDNAs) were synthesized by the SuperScript III First-Strand Synthesis System (Thermo Fisher Scientific) from 1 μg of total RNA in 20 μl of reaction mixture. The resulting cDNA (50 ng) in 20 μl of qRT-PCR mixture with SYBR Premix Ex Taq II (Tli RNase H Plus) (Takara Bio) was subjected to qRT-PCR on Takara Thermal Cycler Dice (TP800), in accordance with the manufacturer’s protocol (Takara Bio). The primers BGT49F (5′-caccttccacctctcttgaacc-3′) and BGT133R (5′-aagtgtgtgtgccgatgaatg-3′) were used for CtA3′5′GT expression analyses. Expression of CamF3′5′H mRNA and actin mRNA as a control was analyzed as previously described (6). Levels of transgene mRNAs were normalized to actin mRNA and were presented relative to transformant 1916-18, which contained 65% of delphinidin-based anthocyanins and the same total anthocyanin content as wild type. Flower color measurement The ray floret colors of chrysanthemum flowers were evaluated under fluorescent light with reference to the RHS Colour Charts (5th edition). The L* value for lightness, a* value for redness/greenness, and b* value for yellowness/blueness of CIEL*a*b* color space were measured in at least three replicates by a CD100 spectrum colorimeter (Yokogawa Meters and Instruments). The color hue angle (H°) and C* value indicating chroma were calculated based on the L*a*b* values. We calculated H° values and C* values by the arctangent of b*/a* and the square root of the sum of (a*)2 and (b*)2, respectively. Absorbance spectra of fresh petals of chrysanthemums were analyzed with an integrated sphere attachment ISR-2200 on a Shimadzu UV-2450 spectrophotometer (Shimadzu). LC-MS analyses LC-MS analysis was performed by an ACQUITY UPLC system with an ACQUITY TQD tandem mass spectrometer (Waters Japan) using an ACQUITY UPLC BEH C18 column [1.7 μm particle diameter, 2.1 mm inner diameter (i.d.) × 100 mm; Waters] at 35°C. The mobile phase was composed of 1% formic acid containing water (solvent A) and 1% formic acid containing acetonitrile (MeCN) (solvent B). A solvent gradient of 0 to 35% B (0 to 40 min) and 35% B (40 to 45 min) at a flow rate of 0.1 ml min−1 was used. Chromatograms were obtained at 360 nm for acylquinates and flavonoids and 530 nm for anthocyanins; photodiode array spectra were recorded from 200 to 800 nm. The measurement conditions were as follows: positive ion mode; capillary voltage, 3.5 kV; cone voltage, 10 V; source block temperature, 150°C; desolvation temperature, 350°C; flow rate of desolvation gas, 500 liters hour−1; flow rate of cone gas, 50 liters hour−1; collision energy, 20 to 50 V; scan range, 180 to 1080 m/z; detector voltage, 1.7 kV. Cross-TLC method for copigment detection A 10% acetic acid extract from blue petals of transgenic chrysanthemums was loaded on a cellulose TLC glass plate (100 × 100 mm; Merck Millipore), as previously described (20). The loaded TLC plate was developed with n-butyl alcohol/acetic acid/water (4:1:2, v/v) at room temperature. After the developed plate had been air-dried, the coloration change and associated compounds were observed on fluorescent light (light box New5000 inverter, Fujicolor) and under UV light (254/365 nm; CSN-15 AC, Cosmo-Bio). The R f values of anthocyanins on cellulose TLC were as follows: ternatin C5 (A8), 0.15; preternatin C5 (A7), 0.11; cyanidin 3-O-(6″-O-malonyl)glucoside-3′-O-glucoside (A3), 0.30. We recovered cellulose powders containing copigment candidates from the TLC plate by spatula and soaked them with 300 μl of 10% acetic acid containing 40% MeCN solution to reextract the copigments. The extracts were centrifuged and filtered for analysis by LC-MS. Isolation of anthocyanins and flavones Frozen petals from blue-colored chrysanthemums (fresh weight, ~2.5 kg) were soaked in ~5.9 liters of 10% formic acid and filtered through a 100-mesh filter. This operation was repeated with 6 liters of 10% formic acid. The combined extract containing flavonoids was centrifuged at 3000 rpm for 10 min, and the supernatant was passed through and adsorbed on a column containing 3 liters of Diaion HP-20 resin (Mitsubishi Kasei). The column was washed with 9 liters of 0.1% formic acid, and anthocyanins and flavonoids were eluted with 0.1% formic acid in methyl alcohol (MeOH). After evaporation and lyophilization, the residue (14.2 g) was dissolved in 0.1% formic acid in 20% MeCN and separated by chromatography on YMC-Pack ODS A (S-15 μm, 50 mm i.d. × 250 mm) in the same solvent, at a flow rate of 30 ml min−1 and with detection at 360 nm. We collected 11 consecutive fractions: Delphinidin 3,3′,5′-tri-O-glucoside (A7; preternatin C5), delphinidin 3-O-(6″-O-malonyl)glucoside-3′,5′-di-O-glucoside (A8; ternatin C5), and cyanidin 3-O-(6″-O-malonyl)glucoside-3′-O-glucoside (A3; Cy3MG3′G) were collected in fraction 1; tricetin 7-O-(6″-O-malonyl)glucoside (C2; Tr7MG) was collected in fraction 2; and luteolin 7-O-(6″-O-malonyl)glucoside (C1; Lt7MG) was collected in fraction 3. Each fraction was evaporated and lyophilized and then dissolved in 0.1% formic acid in 10% MeCN. Fraction 1 was treated by preparative HPLC for rough separation of A3 and A8 using 0.1% formic acid in 35% MeOH at a flow rate of 30 ml min−1. A3 and A8 were finally purified and isolated from these fractions by preparative HPLC using 0.5% formic acid in 20% MeOH, at a flow rate of 28 ml min−1 and with detection at 530 nm. C1 and C2 were isolated from fractions 2 and 3, respectively, by preparative HPLC using 0.1% formic acid in 35% MeOH, at a flow rate of 30 ml min−1 and with detection at 280 nm. The two isolated anthocyanins and two flavone fractions were evaporated and lyophilized; ternatin C5 (A8; 52 mg), Cy3MG3′G (A3; 9.8 mg), Lt7MG (C1; 201.5 mg), and Tr7MG (C2; 52 mg) were obtained as dark reddish or yellowish powders. High-resolution MS analysis High-resolution mass spectra of purified anthocyanins and flavones were obtained by an Agilent 1200 LC instrument equipped with electrospray ionization–time-of-flight–MS (JMS-T100LP, JEOL). Samples were dissolved in MeOH (0.01 mg ml−1), and 10- to 20-μl aliquots were analyzed. The measurement conditions were as follows: solvent, MeOH; needle voltage, 2.2 kV; orifice 1 voltage, 85 V; orifice 2 voltage, 10 V; ring lens voltage, 25 V; peaks voltage, 2 kV; flow rate of drying gas, 1 liter min−1; flow rate of nebulizing gas, 0.5 liter min−1; desolvating temperature, 250°C; orifice 1 temperature, 80°C. The high-resolution MS data are provided in Supplementary Materials and Methods. NMR experiments of anthocyanins and copigments Anthocyanins A8 and A3 were purified from petals of blue-colored transgenic chrysanthemums. A8 and A3 were dissolved in 10% (v/v) trifluoroacetic acid (TFA)–CD 3 OD mixture and TFA–dimethyl sulfoxide (DMSO)–d 6 mixture, respectively. The purified copigments C1 and C2 from petals of blue-colored transgenic chrysanthemums were dissolved in DMSO-d 6 . 1H NMR and NOESY spectra of anthocyanins and 1H NMR, 13C NMR, HMBC, HMQC, and homonuclear correlation spectroscopy spectra of copigments were obtained on a JNM-ECZ600R/S1 spectrometer (JEOL). The observation frequency for 1H and 13C measurement was 600.17 and 150.91 MHz, respectively. The residual proton peak of CD 3 OD was used as the internal standard (3.3 parts per million). The NMR data are provided in Supplementary Materials and Methods. Petal color reconstruction experiments The petal color reconstruction experiments were conducted in acetate buffer at pH 5.6, the average pH value of petals in homogenate measurements. Petals (~5 g) of chrysanthemums were ground in liquid nitrogen and soaked in 15 ml of distilled water. The petal juice was measured immediately with a D-71 pH meter equipped with a 9611-10D pH electrode (Horiba). The concentrations (nanomoles per milligram of petals) of anthocyanins and flavones in petals were calculated, with reference to standard graphs of delphinidin 3-glucoside (Funakoshi) and luteolin (Funakoshi), from the HPLC peak area at 530 and 360 nm, respectively. The flavones—luteolin 7-O-glucoside (C1′), apigenin 7-O-glucoside (F1′), C1, and C2—were dissolved in DMSO. C1′ and F1′ were purchased from Funakoshi. The anthocyanins—preternatin C5 (A7), ternatin C5 (A8), A3, delphinidin 3-O-(6″-O-malonyl)glucoside (Dp3MG; A5) (35), and cyanidin 3-O-(6″-O-malonyl)glucoside (Cy3MG, A1) (15, 36)—were dissolved in distilled water. A5 was purified from petals of a butterfly pea mauve line (35). A1 was synthesized and purified from the reaction product of cyanidin 3-glucoside (Funakoshi) and malonyl coenzyme A (Sigma-Aldrich) by using crude enzyme extract from petals of butterfly pea (36). For petal color reconstruction in vitro, buffer solution [96 to 78 μl of 100 mM acetate buffer (pH 5.6)] and flavone (2 to 20 μl of 10 mM flavone in DMSO) were added to a 1.5-ml microcentrifuge tube. Next, anthocyanin (2 μl of 10 mM anthocyanin aqueous solution) was added to the mixture in a total volume of 100 μl, and the absorption spectrum was recorded in a super-micro black cell (path length, 10 mm; Shimadzu) by using a UV-2450 spectrophotometer (Shimadzu). Spectra were also recorded in the presence of metal ions. Divalent magnesium salt, Mg(OAc) 2 , was dissolved at 10 mM in distilled water, and 2 μl were added to the mixture. Trivalent ion salt, FeNH 4 (SO 4 ) 2 , was dissolved at 1 mM in distilled water, and 2 μl were added to the mixture.
SUPPLEMENTARY MATERIALS Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1602785/DC1 Supplementary Materials and Methods fig. S1. Structures of anthocyanins. fig. S2. Schematic representation of binary vectors used for chrysanthemum transformation. fig. S3. Anthocyanin profiles of representative ‘Sei Arabella’ transgenic lines. fig. S4. Flavonoids and caffeoylquinates profiles of representative ‘Sei Arabella’ transgenic lines. fig. S5. LC-MS analysis of copigment extract from a cellulose TLC plate. fig. S6. Flavonoids and caffeoylquinates profiles of whole and epidermal petal tissue from a blue transgenic line. table S1. Flower color changes due to expression of CamF3′5′H and/or CtA3′5′GT. table S2. Anthocyanin and flavone content and their ratios in petals of ‘Sei Arabella’ and blue/violet-blue–colored transgenic chrysanthemums. table S3. Primer sets used in binary vector construction.
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REFERENCES AND NOTES ↵ T. A. Holton , F. Brugliera , D. R. Lester , Y. Tanaka , C. D. Hyland , J. G. T. Menting , C.-Y. Lu , E. Farcy , T. W. Stevenson , E. C. Cornish , Cloning and expression of cytochrome P450 genes controlling flower colour . Nature 366 , 276 – 279 ( ). ↵ Y. Fukui , Y. Tanaka , T. Kusumi , T. Iwashita , K. Nomoto , A rationale for the shift in colour towards blue in transgenic carnation flowers expressing the flavonoid 3′,5′-hydroxylase gene . Phytochemistry 63 , 15 – 23 ( ). Y. Tanaka, F. Brugliera, in Flowering and its Manipulation, vol. 20 of Annual Plant Reviews, C. Ainsworth, Ed. (Blackwell, 2006), chap. 9. Y. Katsumoto , M. Fukuchi-Mizutani , Y. Fukui , F. Brugliera , T. A. Holton , M. Karan , N. Nakamura , K. Yonekura-Sakakibara , J. Togami , A. Pigeaire , G.-Q. Tao , N. S. Nehra , C.-Y. Lu , B. K. Dyson , S. Tsuda , T. Ashikari , T. Kusumi , J. G. Mason , Y. Tanaka , Engineering of the rose flavonoid biosynthetic pathway successfully generated blue-hued flowers accumulating delphinidin . Plant Cell Physiol. 48 , 1589 – 1600 ( ). ↵ Y. Tanaka , F. Brugliera , Flower colour and cytochromes P450 . Philos. Trans. R. Soc. Lond. B Biol. Sci. 368 , 20120432 ( ). ↵ N. Noda , R. Aida , S. Kishimoto , K. Ishiguro , M. Fukuchi-Mizutani , Y. Tanaka , A. Ohmiya , Genetic engineering of novel bluer-colored chrysanthemums produced by accumulation of delphinidin-based anthocyanins . Plant Cell Physiol. 54 , 1684 – 1695 ( ). ↵ F. Brugliera , G.-Q. Tao , U. Tems , G. Kalc , E. Mouradova , K. Price , K. Stevenson , N. Nakamura , I. Stacey , Y. Katsumoto , Y. Tanaka , J. G. Mason , Violet/blue chrysanthemums—Metabolic engineering of the anthocyanin biosynthetic pathway results in novel petal colors . Plant Cell Physiol. 54 , 1696 – 1710 ( ). ↵ K. Yoshida , M. Mori , T. Kondo , Blue flower color development by anthocyanins: From chemical structure to cell physiology . Nat. Prod. Rep. 26 , 884 – 915 ( ). ↵ N. Sasaki , T. Nakayama , Achievements and perspectives in biochemistry concerning anthocyanin modification for blue flower coloration . Plant Cell Physiol. 56 , 28 – 40 ( ). ↵ P. Trouillas , J. C. Sancho-García , V. De Freitas , J. Gierschner , M. Otyepka , O. Dangles , Stabilizing and modulating color by copigmentation: Insights from theory and experiment . Chem. Rev. 116 , 4937 – 4982 ( ). ↵ T. Kondo , K. Yoshida , A. Nakagawa , T. Kawai , H. Tamura , T. Goto , Structural basis of blue-colour development in flower petals from Commelina communis . Nature 358 , 515 – 518 ( ). ↵ M. Shiono , N. Matsugaki , K. Takeda , Phytochemistry: Structure of the blue cornflower pigment . Nature 436 , 791 ( ). ↵ K. Yoshida , T. Kondo , Y. Okazaki , K. Katou , Cause of blue petal colour . Nature 373 , 291 ( ). ↵ S. Fukuda-Tanaka , Y. Inagaki , T. Yamaguchi , N. Saito , S. Iida , Colour-enhancing protein in blue petals . Nature 407 , 581 ( ). ↵ N. Saito , K. Toki , T. Honda , K. Kawase , Cyanidin 3-malonylglucuronylglucoside in Bellis and cyanidin 3-malonylglucoside in Dendranthema . Phytochemistry 27 , 2963 – 2966 ( ). ↵ M. Nakayama , M. Koshioka , M. Shibata , S. Hiradate , H. Sugie , M.-a. Yamaguchi , Identification of cyanidin 3-O-(3″,6″-O-dimalonyl-β-glucopyranoside) as a flower pigment of Chrysanthemum (Dendranthema grandiflorum) . Biosci. Biotechnol. Biochem. 61 , 1607 – 1608 ( ). ↵ N. Terahara , K. Toki , N. Saito , T. Honda , T. Matsui , Y. Osajima , Eight new anthocyanins, ternatins C1–C5 and D3 and preternatins A3 and C4 from young Clitoria ternatea flowers . J. Nat. Prod. 61 , 1361 – 1367 ( ). ↵ K. Kogawa , N. Kato , K. Kazuma , N. Noda , M. Suzuki , Purification and characterization of UDP-glucose: Anthocyanin 3′,5′-O-glucosyltransferase from Clitoria ternatea . Planta 226 , 1501 – 1509 ( ). ↵ H. He , H. Ke , H. Keting , X. Qiaoyan , D. Silan , Flower colour modification of chrysanthemum by suppression of F3′H and overexpression of the exogenous Senecio cruentus F3′5′H gene . PLOS ONE 8 , e74395 ( ). ↵ H. Shimizu-Yumoto , N. Hayashi , K. Ichimura , M. Nakayama , Slantingly cross loading sample system enables simultaneous performance of separation and mixture to detect molecular interactions on thin-layer chromatography . J. Chromatogr. A 1245 , 183 – 189 ( ). ↵ K. E. Schwinn , K. R. Markham , N. K. Giveno , Floral flavonoids and the potential for pelargonidin biosynthesis in commercial chrysanthemum cultivars . Phytochemistry 35 , 145 – 150 ( ). ↵ T. Sugawara , K. Igarashi , Identification of major flavonoids in petals of edible chrysanthemum flowers and their suppressive effect on carbon tetrachloride-induced liver injury in mice . Food Sci Technol. Res. 15 , 499 – 506 ( ). ↵ N. Saito , J. B. Harborne , A cyanidin glycoside giving scarlet coloration in plants of the Bromeliaceae . Phytochemistry 22 , 1735 – 1740 ( ). J. B. Harborne, R. J. Grayer, in The Flavonoids: Advances in Research Since 1980, J. B. Harborne, Ed. (Springer, 1988), chap. 1. Ø. M. Andersen, M. Jordheim, in Flavonoids: Chemistry, Biochemistry and Applications, Ø. M. Andersen, K. R. Markham, Eds. (Taylor & Francis, 2006), chap. 10. ↵ Ø. M. Andersen, M. Jordheim, in Comprehensive Natural Products II: Chemistry and Biology, L. Mander, H.-W. Liu, Eds. (Elsevier Science, 2010), chap. 3.16. ↵ Ø. Bjorøy , T. Fossen , Ø. M. Andersen , Anthocyanin 3-galactosides from Cornus alba ‘Sibirica’ with glucosidation of the B-ring . Phytochemistry 68 , 640 – 645 ( ). ↵ K. Takeda , J. B. Harborne , P. G. Waterman , Malonylated flavonoids and blue flower colour in lupin . Phytochemistry 34 , 421 – 423 ( ). ↵ R. Aida , K. Yoshida , T. Kondo , S. Kishimoto , M. Shibata , Copigmentation gives bluer flowers on transgenic torenia plants with the antisense dihydroflavonol-4-reductase gene . Plant Sci. 160 , 49 – 56 ( ). ↵ E. E. Hood , S. B. Gelvin , L. S. Melchers , A. Hoekema , New Agrobacterium helper plasmids for gene transfer to plants . Transgenic Res. 2 , 208 – 218 ( ). ↵ M. Kuroda , M. Kimizu , C. Mikami , A simple set of plasmids for the production of transgenic plants . Biosci. Biotechnol. Biochem. 74 , 2348 – 2351 ( ). ↵ S. Nagaya , K. Kawamura , A. Shinmyo , K. Kato , The HSP terminator of Arabidopsis thaliana increases gene expression in plant cells . Plant Cell Physiol. 51 , 328 – 332 ( ). ↵ J. Satoh , K. Kato , A. Shinmyo , The 5′-untranslated region of the tobacco alcohol dehydrogenase gene functions as an effective translational enhancer in plant . J. Biosci. Bioeng. 98 , 1 – 8 ( ). ↵ D. Miki , K. Shimamoto , Simple RNAi vectors for stable and transient suppression of gene function in rice . Plant Cell Physiol. 45 , 490 – 495 ( ). ↵ K. Kazuma , N. Noda , M. Suzuki , Flavonoid composition related to petal color in different lines of Clitoria ternatea . Phytochemistry 64 , 1133 – 1139 ( ). ↵ K. Kogawa , K. Kazuma , N. Koto , N. Noda , M. Suzuki , Biosynthesis of malonylated flavonoid glycosides on the basis of malonyltransferase activity in the petals of Clitoria ternatea . J. Plant Physiol. 164 , 886 – 894 ( ). | – A development of "great impact" has been made in the world of flowers—specifically among chrysanthemums, which researchers have just turned a true-blue hue for the first time, per Science. The magazine explains that vibrant blue flowers are hard to find in nature—only a few species exist, and others we think are blue are really more purple or violet. Scientists have long tried to manufacture blue versions of flowers, but the complexities of plant pigmentation have stymied them: For a flower to "turn" blue, pigment molecules called anthocyanins have to have just the right amount of sugar or other atoms, and the plant cells have to offer just the right conditions. A Cornell scientist tells Science News that such a flower is the "Holy Grail," while a University of Florida plant biotechnologist says previous efforts have "never worked perfectly." Until now. In a study published in the Science Advances journal, success came via the work of Naonobu Noda, a plant biologist in Japan who used a double-punch technique to turn a chrysanthemum blue, per the Royal Horticultural Society's color scale. He inserted not one, but two genes into his samples: one from the bluish Canterbury bell flower, another from the butterfly pea. And although his team had anticipated having to add a third, two did the trick, as a color-free component already in the chrysanthemum interacted well with the altered anthocyanin. Per Nature, the scientists say this genetic alteration may also be used on other commercially coveted flowers such as carnations and lilies, though Noda tells NPR we likely won't see these modified blooms in florists anytime soon. (Monsanto wants to make flowers that "bloom on command.") |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Bear Protection Act of 1999''.
SEC. 2. FINDINGS.
Congress finds that--
(1) all 8 extant species of bear--Asian black bear, brown
bear, polar bear, American black bear, spectacled bear, giant
panda, sun bear, and sloth bear--are listed on Appendix I or II
of the Convention on International Trade in Endangered Species
of Wild Fauna and Flora (27 UST 1087; TIAS 8249) (referred to
in this section as ``CITES'');
(2) Article XIV of CITES provides that Parties to CITES may
adopt stricter domestic measures regarding the conditions for
trade, taking, possession, or transport of species on Appendix
I or II, and the Parties to CITES adopted a resolution (Conf.
10.8) urging Parties to take immediate action to demonstrably
reduce the illegal trade in bear parts and derivatives;
(3) the Asian bear populations have declined significantly
in recent years, as a result of habitat loss and poaching due
to a strong demand for bear viscera used in traditional
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(4) Federal and State undercover operations have revealed
that American bears have been poached for their viscera;
(5) while most American black bear populations are
generally stable or increasing, commercial trade could
stimulate poaching and threaten certain populations if the
demand for bear viscera increases; and
(6) prohibitions against the importation into the United
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prohibitions against the interstate trade, of bear viscera and
products containing, or labeled or advertised as containing,
bear viscera will assist in ensuring that the United States
does not contribute to the decline of any bear population as a
result of the commercial trade in bear viscera.
SEC. 3. PURPOSES.
The purpose of this Act is to ensure the long-term viability of the
world's 8 bear species by--
(1) prohibiting international trade in bear viscera and
products containing, or labeled or advertised as containing,
bear viscera;
(2) encouraging bilateral and multilateral efforts to
eliminate such trade; and
(3) ensuring that adequate Federal legislation exists with
respect to domestic trade in bear viscera and products
containing, or labeled or advertised as containing, bear
viscera.
SEC. 4. DEFINITIONS.
In this Act:
(1) Bear viscera.--The term ``bear viscera'' means the body
fluids or internal organs, including the gallbladder and its
contents but not including blood or brains, of a species of
bear.
(2) Import.--The term ``import'' means to land on, bring
into, or introduce into any place subject to the jurisdiction
of the United States, whether or not the landing, bringing, or
introduction constitutes an importation within the meaning of
the customs laws of the United States.
(3) Person.--The term ``person'' means--
(A) an individual, corporation, partnership, trust,
association, or other private entity;
(B) an officer, employee, agent, department, or
instrumentality of--
(i) the Federal Government;
(ii) any State, municipality, or political
subdivision of a State; or
(iii) any foreign government;
(C) a State, municipality, or political subdivision
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(D) any other entity subject to the jurisdiction of
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(4) Secretary.--The term ``Secretary'' means the Secretary
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of Columbia, the Commonwealth of Puerto Rico, the Virgin
Islands, Guam, the Commonwealth of the Northern Mariana
Islands, American Samoa, and any other territory, commonwealth,
or possession of the United States.
(6) Transport.--The term ``transport'' means to move,
convey, carry, or ship by any means, or to deliver or receive
for the purpose of movement, conveyance, carriage, or shipment.
SEC. 5. PROHIBITED ACTS.
(a) In General.--Except as provided in subsection (b), a person
shall not--
(1) import into, or export from, the United States bear
viscera or any product, item, or substance containing, or
labeled or advertised as containing, bear viscera; or
(2) sell or barter, offer to sell or barter, purchase,
possess, transport, deliver, or receive, in interstate or
foreign commerce, bear viscera or any product, item, or
substance containing, or labeled or advertised as containing,
bear viscera.
(b) Exception for Wildlife Law Enforcement Purposes.--A person
described in subparagraph (B) or (C) of section 4(3) may import into,
or export from, the United States, or transport between States, bear
viscera or any product, item, or substance containing, or labeled or
advertised as containing, bear viscera if the importation, exportation,
or transportation--
(1) is solely for wildlife law enforcement purposes; and
(2) is authorized by a valid permit issued under Appendix I
or II of the Convention on International Trade in Endangered
Species of Wild Fauna and Flora (27 UST 1087; TIAS 8249), in
any case in which such a permit is required under the
Convention.
SEC. 6. PENALTIES AND ENFORCEMENT.
(a) Criminal Penalties.--A person that knowingly violates section 5
shall be fined under title 18, United States Code, imprisoned not more
than 1 year, or both.
(b) Civil Penalties.--
(1) Amount.--A person that knowingly violates section 5 may
be assessed a civil penalty by the Secretary of not more than
$25,000 for each violation.
(2) Manner of assessment and collection.--A civil penalty
under this subsection shall be assessed, and may be collected,
in the manner in which a civil penalty under the Endangered
Species Act of 1973 may be assessed and collected under section
11(a) of that Act (16 U.S.C. 1540(a)).
(c) Products, Items, and Substances.--Any bear viscera, or any
product, item, or substance sold, imported, or exported, or attempted
to be sold, imported, or exported, in violation of this section
(including any regulation issued under this section) shall be seized
and forfeited to the United States.
(d) Regulations.--After consultation with the Secretary of the
Treasury, the Secretary of Health and Human Services, and the United
States Trade Representative, the Secretary shall issue such regulations
as are necessary to carry out this section.
(e) Enforcement.--The Secretary, the Secretary of the Treasury, and
the Secretary of the department in which the Coast Guard is operating
shall enforce this section in the manner in which the Secretaries carry
out enforcement activities under section 11(e) of the Endangered
Species Act of 1973 (16 U.S.C. 1540(e)).
(f) Use of Penalty Amounts.--Amounts received as penalties, fines,
or forfeiture of property under this section shall be used in
accordance with section 6(d) of the Lacey Act Amendments of 1981 (16
U.S.C. 3375(d)).
SEC. 7. DISCUSSIONS CONCERNING TRADE PRACTICES.
The Secretary and the Secretary of State shall discuss issues
involving trade in bear viscera with the appropriate representatives of
countries trading with the United States that are determined by the
Secretary and the United States Trade Representative to be the leading
importers, exporters, or consumers of bear viscera, and attempt to
establish coordinated efforts with the countries to protect bears.
SEC. 8. REPORT.
Not later than 1 year after the date of enactment of this Act, the
Secretary, in cooperation with appropriate State agencies, shall submit
to the Committee on Environment and Public Works of the Senate and the
Committee on Resources of the House of Representatives a report
detailing the progress of efforts to end the illegal trade in bear
viscera. | Bear Protection Act of 1999 - Prohibits any person from: (1) importing bear viscera into, or exporting it from, the United States; or (2) selling bear viscera, bartering, offering it for sale or barter, or purchasing, possessing, transporting, delivering, or receiving it in interstate or foreign commerce. Subjects persons who violate such prohibitions to specified penalties. Waives such prohibition for wildlife law enforcement purposes where a valid permit has been issued.
Requires the Secretary of the Interior and the Secretary of State to discuss issues involving such trade with the appropriate representatives of countries that are the leading importers, exporters, or consumers of such products. Requires the Secretary of the Interior to report to Congress on the progress of efforts to end illegal trade in bear viscera. |
turbulent magnetic fields play an important role in many astrophysical processes such as amplification of magnetic fields , accretion , viscous heating and thermal conduction in a turbulent magnetised plasma , etc . @xcite .
one of the most important processes where the presence of turbulent magnetic fields is necessary is the diffusive shock acceleration . in particular ,
the collisionless shock waves themselves are generated via magnetic turbulence , which mediates interactions between particles . in the acceleration process
the turbulence is required to trap accelerated particles around shock front for successive crossings , in which they gain energy .
the acceleration of the particles is accompanied by their radiation .
the character of the radiation can reveal details of the acceleration as well as the properties of the turbulent medium where the acceleration occurs .
the geometry and the scale of turbulence could be reflected in the polarization properties of the radiation .
a completely isotropic turbulence does not produce any net polarization .
however , if the scale of the turbulence is sufficiently large one can detect the fluctuations of the polarization and study the structure of the magnetic field @xcite . in the case of small - scale turbulence , the only way to observe a polarised radiation is the specific anisotropic geometry of the turbulent magnetic field .
this concerns , for example , the objects like grbs . the turbulent magnetic fields in the shock waves can be generated by a variety of plasma instabilities @xcite .
particle - in - cell ( pic ) simulations show that a weibel instability is a key component for generation of the relativistic collisionless shock waves and amplification of magnetic fields @xcite . as proposed in ref .
@xcite in the context of the magnetic field amplification in grbs , the anisotropy of colliding beams is transferred to the energy of the small - scale turbulent magnetic field .
the characteristic scale of the turbulence is of the order of the plasma skin - depth .
here it is interesting to note that the amplification occurs predominantly for the components of the field which are perpendicular to the direction of beams . the analysis of pic simulations conducted in ref .
@xcite reveals also a significant anisotropy of the turbulence at the saturation stage of amplification .
however , the turbulence becomes more isotropic in a course of non - linear evolution far behind the shock front @xcite .
the radiation of electrons in the small - scale magnetic fields significantly differs from the regular synchrotron radiation @xcite . because of the turbulence
, the formation length of the radiation can be smaller than the formation length required for synchrotron radiation . in this case the qualitatively different type of radiation - jitter radiation - appears .
the conditions for realization of this regime of radiation is the smallness of the characteristic length of the turbulence @xmath0 compared to the _ non - relativistic _ larmor radius @xmath1 .
thus the appearance of the jitter radiation is determined solely by the properties of the magnetic field . because of smaller formation length , the characteristic frequency of jitter radiation @xmath2 is larger than the characteristic frequency of synchrotron radiation @xmath3 by the factor @xmath4 , i.e. @xmath5 , where @xmath6 .
the mechanism of jitter radiation has been revisited in ref .
it has been shown that the power spectrum of radiation behaves as a constant at frequencies smaller than the characteristic frequency of jitter radiation , contrary to the earlier claimed @xmath7 behaviour @xcite .
the spectrum at high frequencies is a power - law with index determined by the turbulent spectrum .
the total power of the jitter radiation equals the total power of the synchrotron radiation in the isotropic magnetic field .
thus presence of the small - scale turbulence affects the radiation spectrum but does not touch total losses . in this paper
we show that a similar relation occurs for polarisation properties : the turbulence influences only the spectral degree of polarisation whereas the degree of polarisation of total radiation is the same for jitter and synchrotron radiations . concerning the polarisation of radiation from grbs ,
the synchrotron radiation is assumed to be the main mechanism for the production of polarised emission .
while the weibel instability seems to be inevitable in generation of inner and outer shocks , it is not clear whether the weibel instability indeed produces small enough turbulence for the operation of the jitter regime .
the simulations of ref .
@xcite show that the jitter radiation regime can operate during the growing stage while the current filaments merge , and , at the later times , after reaching the non - linear regime when magnetic field starts to decay .
while the growth of the magnetic field occurs very fast , the decaying stage looks more promising for production of significant portion of jitter radiation . at the saturation stage
, it is more probable that the synchrotron regime is at work .
so it makes a sense to consider the polarisation properties of both synchrotron and jitter regimes for a specific configuration of the turbulent magnetic field generated by weibel instability .
the polarisation properties of the radiation in the turbulent magnetic field with the so - called slab geometry have been studied in refs .
@xcite . assuming an independence of the radiation from different parts of the emitting region , laing @xcite has averaged the radiation from power - law electron distribution over the isotropically distributed directions of the magnetic field in the plane .
while this approach works for synchrotron radiation , the calculations in the case of jitter radiation should take into account the coherence of the turbulent magnetic field .
this has not been done in the calculations of ref .
@xcite where the polarisation of jitter radiation has been studied in the manner of ref .
it has led them to incorrect the conclusion that jitter radiation can give a @xmath8 polarisation .
in this paper we study the polarisation properties of the radiation from isotropically distributed electrons in a turbulent magnetic field with slab geometry .
the calculations have been conducted in the general tensor form which is not attached to any specific coordinate system and allows us to avoid any assumptions about principle axis of the polarisation ellipse .
for calculations we follow the approach proposed in ref .
the averaging of the obtained formulae for jitter radiation over all directions of observation reproduces the results obtained for the isotropic turbulence considered in ref .
the derived formulae can be used for an arbitrary energy distribution of electrons .
we compare the polarisation properties of the synchrotron and jitter radiation and show that the synchrotron radiation is more polarised in the case of monoenergetic distributions . for the power - law distribution of electrons the analytical formula for the degree of polarisation of jitter radiation
is obtained .
the paper has the following structure . sections 2 and 3 describe the calculations of the polarization produced in the jitter and synchrotron radiation regimes , respectively . in the section 4 we present the results and compare two cases .
finally , in section 5 we discuss the main results and make conclusions .
the spectral power of the emission of a charged particle at the moment @xmath9 can be written in the form @xcite : @xmath10 where @xmath11}{(1-\b n\b \beta(t))^2 } e^{i\phi(t)}.\ ] ] the complex vector @xmath12 depends on time through the particle velocity @xmath13 , the acceleration @xmath14 , and the exponential factor @xmath15 , which depends on the radius - vector of the particle .
here @xmath16 is the unit vector in the direction of observation .
the function @xmath17 is the complex conjugation of @xmath12 .
( [ eq : pow ] ) gives the total power of radiation per unit frequency and per unit solid angle irrespective of polarization . to take into account the directions of the oscillation of the electric field vector in the electromagnetic wave
, one should consider instead of just the scalar product the direct product of the electric field vector in the fourier space .
this can be done by rewriting eq .
( [ eq : pow ] ) in the tensor form : @xmath18 the intensity of the radiation polarized in the direction @xmath19 then can be easily found as @xmath20 .
note that the quantity @xmath21 is the equivalent of the polarization tensor which is usually determined as @xmath21 normalised to the intensity @xmath22 @xcite . in this paper , for convenience , we refer to this quantity as polarization tensor .
the jitter radiation is realized in the small - scale chaotic magnetic field with the correlation length @xmath0 smaller that nonrelativistic larmor radius @xmath23 .
we assume that statistically averaged magnetic field is @xmath24 .
the radiation should be averaged over all possible configurations of magnetic field . under this condition
@xmath0 determines the scale of particle path where the observed radiation is generated . at distances @xmath25 ,
the particle radiation is incoherent . the value of the integrand in eq .
( [ eq : powik ] ) tends to zero at @xmath26 because the magnetic fields become uncorrelated and the time - averaged product @xmath27 . as discussed in ref .
@xcite , the condition @xmath28 allows us to perform the calculations in the framework of perturbation theory . since @xmath29 , we can assume , as a zeroth approximation , that @xmath30 , @xmath31 . with such accuracy , we have @xmath32 where @xmath33 , @xmath34 $ ] , @xmath35 , and @xmath36 .
the tensor @xmath37 has a quite complicated structure .
if the distribution of the particles is isotropic one can simplify @xmath37 by averaging directions of the velocity @xmath38 over the azimuthal angle with respect to the direction of observation @xmath16 .
the tensor can be further simplified taking into account that the angle between @xmath39 and @xmath16 is small ( @xmath40 ) and @xmath41 .
after tedious calculations , we obtain @xmath42 where the fourth - rank tensor @xmath43 is @xmath44 here we have introduced the variable @xmath45 , where @xmath46 is the angle between @xmath39 and @xmath16 .
the tensor @xmath47 is the two - dimensional kronecker delta perpendicular to the direction @xmath16 .
taking into account relativistic effects we can write in these designations @xmath48 and @xmath49 to continue the further calculations one should average eq .
( [ eq : powik1 ] ) over all possible configurations of the magnetic field .
this leads to appearance of the correlation function @xmath50 where @xmath51 , @xmath52 , @xmath53 , and @xmath54 .
we consider the case of the two - dimensional stochastic magnetic field with directions parallel to a plane .
let us introduce a vector @xmath55 which is the normal unit vector to the plane .
then the correlation function should satisfy the following conditions @xmath56 following to the procedure described in ref .
@xcite , the correlation function of the statistically homogeneous and stationary field could be presented in the form of a fourier integral : @xmath57 where @xmath58 and @xmath59 . because of the condition @xmath60 , the fourier components of the correlation function obey the transversality conditions : @xmath61 taking into account the conditions of eq .
( [ eq : kpers ] ) and eq .
( [ eq : kperq ] ) , the most general form of the correlation function is @xmath62 where @xmath63 and @xmath64 . below
we will consider the case of stationary magnetic fields with the function @xmath65 which does not depend on the scalar product @xmath66 : @xmath67 here @xmath68 is the dirac delta function , and the function @xmath69 is normalised such that @xmath70 combining eqs .
( [ eq : powik1],[eq : kdef],[eq : kexp],[eq : kfform ] ) we obtain @xmath71 here the integration over @xmath72 has been cancelled using @xmath68 in eq .
( [ eq : psit ] ) and the velocity @xmath38 in the exponent has been substituted by @xmath16 . to find the total radiation power emitted by an isotropic distribution of the particles in the direction @xmath16 ,
let us integrate eq .
( [ eq : powik2 ] ) over directions of velocity @xmath38 . because the angle between @xmath73 and @xmath16 is small
, one can adopt @xmath74 .
it is convenient to perform this integration using variable @xmath45 with limits of integration from zero to infinity : @xmath75 this integral is calculated using the delta function @xmath76 appearing after the integration over @xmath77 in eq .
( [ eq : powik2 ] ) : @xmath78 where @xmath79 here @xmath80 is the cosine of the angle between @xmath81 and @xmath16 , @xmath82 is the azimuthal angle of @xmath81 relative to the direction of @xmath16 , and the tensor @xmath83 .
taking into account that @xmath84 is symmetric tensor , the tensor part of the integrand is simplified to @xmath85 where @xmath86 is a two - dimensional tensor perpendicular to the direction @xmath16 ; it is expressed as @xmath87 let us introduce two - dimensional projection of the vector @xmath55 on the plane perpendicular to the direction @xmath16 @xmath88 then the tensor @xmath86 integrated over azimuthal angle @xmath82 should have the following structure @xmath89 the trace of the tensor and contraction with tensor @xmath90 results in two algebraic equations .
the solution of these equations is @xmath91 where @xmath92 the integration over the azimuthal angle gives @xmath93 where @xmath94 .
thus the integration of eq .
( [ eq : tk ] ) over the azimuthal angle @xmath82 gives @xmath95 eq .
( [ eq : powik4 ] ) can be rewritten as @xmath96 where @xmath97 here we have changed the integration variable from @xmath98 to @xmath99 using eq .
( [ eq : xisub ] ) and expressed @xmath100 through @xmath99 .
also , for convenience of notations the interchange @xmath101 has been applied .
after rather simple but tedious calculations we obtain @xmath102 @xmath103 where @xmath104 is the heaviside step function , @xmath105 . finally we can write the result as @xmath106 where we suppose that @xmath107 is the two - dimensional kronecker delta , and @xmath108 here the functions @xmath109 and @xmath110 are given by eqs .
( [ eq : f1 ] ) , ( [ eq : f2 ] ) . the functions @xmath111 and @xmath112 correspond up to the common prefactor to the stokes parameters @xmath113 and @xmath114 as they are usually determined .
the lower index @xmath115 refers to the jitter radiation .
the results written in this form are convenient because the degree of polarization can be immediately written as : @xmath116 indeed , the intensity observed in the direction @xmath19 is @xmath117 where @xmath118 is the angle between two two - dimensional vectors @xmath119 and @xmath19 . as @xmath120 and @xmath121 ,
from the definition @xmath122 we obtain eq .
( [ eq : qr ] ) .
let us find the total radiation by integrating the power spectrum @xmath123 over the frequency @xmath124 .
taking into account the normalization condition given by eq .
( [ eq : psinorm ] ) , we obtain @xmath125 the calculations give @xmath126 one can show that the polarisation of the total radiation is expressed as @xmath127 eq .
( [ eq : intpol ] ) represents a general expression for the degree of polarization of the total intensity of ultrarelativistic particles in the magnetic field of given geometry .
below we show that this expression also appears in the case of the synchrotron radiation . the total intensity averaged over directions of @xmath16 ( @xmath128 )
is @xmath129 it coincides with the radiation intensity in the totally chaotic magnetic field ( without a preferred direction ) .
averaging of the power spectrum over directions of @xmath16 leads to @xmath130 where @xmath131 , and @xmath132 the expression coincides with the formula obtained in ref .
the polarization of synchrotron radiation in the case of homogeneous magnetic field is described by the matrix @xcite : @xmath133 where @xmath134 here @xmath135 is the cyclotron frequency of electrons in the magnetic field with the strength @xmath136 , @xmath137 and @xmath138 are the pitch angle and lorentz factor of the radiating electron .
the function @xmath139 and @xmath140 are expressed through the modified bessel functions @xmath141 and @xmath142 in the following way : @xmath143 the power spectrum of synchrotron radiation is obtained as the trace of the matrix in eq .
( [ eq : spsinmat ] ) : @xmath144 the polarisation matrix in eq .
( [ eq : spsinmat ] ) is written in the plane perpendicular to the direction of observation @xmath16 , in a particular system of coordinates where @xmath145 and @xmath146 axes are directed along acceleration @xmath147 and along the direction @xmath148 perpendicular to it , respectively .
let us rewrite eq .
( [ eq : spsinmat ] ) for an arbitrary reference coordinate system in the tensor form : @xmath149 where @xmath150 here @xmath151 is the unit vector in the direction of acceleration @xmath152 , where @xmath153 is the unit vector in the direction of magnetic field . in this expression the velocity @xmath39 can be substituted by @xmath16 .
thus we obtain @xmath154 and @xmath155 let us assume that magnetic field has a slab structure , i.e. the directions of the magnetic field are parallel to a plane . designating the normal vector to the plane as @xmath55 , we can always choose two perpendicular to each other vectors @xmath156 and @xmath157 lying in the plane in a way that vectors @xmath156 , @xmath157 , and @xmath55 constitute a right - handed coordinate system
. then the vectors @xmath16 and @xmath153 are expressed as @xmath158 it follows from eq .
( [ eq : ne1s ] ) that @xmath159 the substitution of eq .
( [ eq : e1e2 ] ) to eq .
( [ eq : be1e2 ] ) leads to @xmath160 then we have @xmath161 notice that @xmath162 is perpendicular to @xmath16 and has only two non - zero components in the system of coordinates with one of the axis directed along @xmath16 .
indeed the vector @xmath163 is the projection of vector @xmath55 on the plane perpendicular to @xmath16 and can be rewritten as @xmath164 where @xmath119 is determined in eq .
( [ eq : detss ] ) .
further we consider @xmath119 as a two - dimensional vector .
analogously , the vector @xmath165 could be written as @xmath166 where @xmath167 is a two - dimensional antisymmetric symbol .
thus , in the plane perpendicular to @xmath16 we can write @xmath168 introducing @xmath169 and @xmath170 , we have @xmath171 then the first tensor in eq .
( [ eq : rhos ] ) can be written as @xmath172 where @xmath107 is the two - dimensional kronecker delta .
taking the vector product of @xmath16 and @xmath162 from eq .
( [ eq : ntb ] ) we obtain @xmath173 analogously , this vector can be written in two - dimensional form : @xmath174 the second tensor in eq .
( [ eq : rhos ] ) has the following form @xmath175 the direction of the magnetic field enters also in the argument of the functions @xmath139 and @xmath140 through the sine of the pitch angle @xmath176 , which can be expressed as @xmath177 taking in mind that at averaging over the angle @xmath178 the expressions with the factor @xmath179 drop out , the tensor @xmath180 in eq .
( [ eq : rhos ] ) can be written as @xmath181 or in the more convenient form @xmath182 finally we can write @xmath183 where @xmath184 here @xmath185 where @xmath186 . here , as before , the functions @xmath187 and @xmath188 correspond up to the prefactor to the stokes parameters @xmath113 and @xmath114 .
the lower index @xmath189 refers to the synchrotron radiation . if the magnetic field is distributed over the strength with the distribution function @xmath190 , we should average the power spectrum in eq .
( [ eq : ppolar ] ) @xmath191 notice that this operation does not change the tensor structure of @xmath192 .
the total power spectrum can be found by taking the trace of @xmath192 : @xmath193 the power spectrum in some particular direction @xmath19 in the plane perpendicular to @xmath16 is @xmath194 i.e. it depends on the scalar product between projection of the normal vector @xmath55 and the direction of the polarizer @xmath195 .
note that the polarization tensor has the same structure as for the case of the jitter radiation .
thus , the degree of polarization of the synchrotron radiation in the slab geometry is @xmath196 the integration of the @xmath192 over the frequency in eq .
( [ eq : pqr ] ) leads to @xmath197 then the degree of polarization of the total radiation is @xmath198 which coincides with eq .
( [ eq : intpol ] ) .
now we analyse the results obtained in the previous sections . in particular , we use eqs .
( [ eq : jittensor]-[eq : qrjit ] ) for the jitter radiation and eqs .
( [ eq : ppolar]-[eq : pqr ] ) for the synchrotron radiation .
the expressions obtained in the previous sections do not specify the exact form of the turbulent spectrum or the distribution over the strength .
below we describe the distributions which are used for the presentation of the final results . in the regime of synchrotron radiation
the spatial correlation of the magnetic fields has no impact on the radiation spectrum .
therefore the variation of the magnetic field can be considered as a set of homogeneous magnetic fields with a certain distribution over the strength and the direction without an introduction of the turbulent spectrum .
the calculations leading to eq .
( [ eq : pqr ] ) have been conducted for the isotropic in the plane magnetic field with the constant strength . assuming that the variations of the magnetic field strength are distributed isotropically and homogeneously along the plane
, one can describe the large - scale turbulence via the distribution over the magnetic field strength : @xmath199 where @xmath200 and @xmath201 . in the same manner as in ref .
@xcite we consider the following three types of distributions : @xmath202 here @xmath203 describes homogeneous magnetic field , @xmath204 is the gauss type distribution with narrow dispersion , and @xmath205 is the distribution of power - law type with wide dispersion around @xmath206 . for all distributions
we have : @xmath207 unlike the synchrotron radiation , the jitter radiation depends on the spacial correlations of the magnetic field , and the turbulence spectrum determines the form of the radiation spectrum .
( [ eq : qrjit ] ) is derived for the homogeneous isotropic turbulence in the plane . in this case
the spectrum of turbulence is described by the scalar function @xmath69 .
it is convenient to present this function in the form @xmath208 which provides convergence of the integrals in eq .
( [ eq : qrjit ] ) at @xmath209 .
the normalization constant that satisfies the condition of eq .
( [ eq : psinorm ] ) is @xmath210 where @xmath211 is the gamma function .
note that the presence of the large - scale turbulence in the form given by eq .
( [ eq : strdist ] ) does not change the results .
indeed , the variance of a small - scale turbulent magnetic field @xmath212 enters linearly to the expressions for the jitter radiation .
averaging of @xmath213 over strength distributions gives , according to eq .
( [ eq : distvar ] ) , @xmath213 again . the results for the degree of polarization of jitter radiation based on eqs .
( [ eq : qrjit],[eq : qr ] ) are shown in figs .
[ fig : jitpolarization53]-[fig : jitpolarization ] .
the curves are calculated for the case of the turbulent spectrum given by eq .
( [ eq : jitturbspec ] ) with correlation length @xmath214 .
the typical behaviour of the polarization degree with frequency for different observation angles is shown in fig .
[ fig : jitpolarization53 ] for the spectral index of turbulence @xmath215 .
the observation angle is counted from the normal to the plane with chaotic magnetic field .
if one observes the plane along the normal ( with line of sight perpendicular to the plane ) , the radiation appears totally unpolarized . in this case
, there is no preferential direction because the directions of the magnetic field are isotropically distributed and the fluxes of the radiation with different polarization are equal .
however , when the observation is conducted at an angle to the normal , the isotropic picture is broken : while the angle between the line of sight and the directions of magnetic field perpendicular to the plane formed by line of sight and the normal remains @xmath216 , the angle in other directions changes .
thus , the fluxes of the radiation with polarization in one direction would be dominant compared to the fluxes with polarization in other directions .
one can see in fig .
[ fig : jitpolarization53 ] that in accordance with this consideration the polarization generally increases with the angle . however , at small frequencies and at angles close to @xmath216 the opposite behaviour is seen . the analysis of the results presented in figs .
[ fig : jitpolarization53]-[fig : jitpolarization ] shows that at angles greater and smaller than @xmath217 , the behaviour of the polarization with frequency is different .
namely , at the angles smaller than @xmath218 the derivative of the degree of polarization is positive at any frequency which means that the polarization is a strictly increasing function of frequency . at low and high frequencies the polarization grows slowly producing some kind of plateaus . between these plateaus
one can observe sharp increase of the polarization located between @xmath219 and @xmath220 around the characteristic frequency of the jitter radiation @xmath221 .
the transition region between the plateaus becomes sharper and starts at lower frequencies with the increase of the observation angel . at the critical angle @xmath218 the polarization changes the sign of the derivative at the point @xmath222 becoming a decreasing function at small frequencies .
for the angle @xmath223 shown in fig .
[ fig : jitpolarization53 ] this values is @xmath224 . because of the very slow variation
, the change of trend at this frequency is barely seen . for larger angles
the point of the minimum where the derivative changes its sign is more pronounced . at the angle
@xmath216 this point shifts to zero .
thus , from the physical point of view , one can consider that at the observation angle @xmath216 the behaviour of the degree of polarization as function of frequency again changes to monotonically increasing function .
one of the explanations of such an interesting behaviour of polarization with the observation angle at small frequencies could be that this is a mathematical artefact due to the delta - functional distribution of the directions of the magnetic field in three - dimensional space ( all the directions lie in the plane ) .
one can show that the polarization degree converges to the constant limit at high frequencies .
indeed , at high frequencies the turbulent spectrum behaves as @xmath225 thus , the degree of polarization is @xmath226 after calculation of the integral we obtain the analytical expression for the maximum of the jitter polarization which depends on the angle of observation ( @xmath227 ) and the spectral index of the turbulence @xmath228 : @xmath229 the value of the high - frequency plateau of the degree of polarization increases with the observation angle and spectral index .
specifically , at the angle @xmath230 the polarization @xmath231 is as high as @xmath232 , @xmath233 , and @xmath234 for the spectral indices @xmath235 , @xmath236 , @xmath237 , respectively ( see fig . [
fig : jitpolarization ] ) .
the polarization at the maximum of the spectral energy distribution @xmath238 is @xmath239 , @xmath240 , and @xmath241 . using eqs .
( [ eq : qrjit ] ) and ( [ eq : jitturbspec ] ) one can show that at low frequencies the degree of polarization as function of frequency also tends to the constant which is now independent on the spectral index of turbulence .
after quite tedious calculations one can obtain that this constant is @xmath242 at the observational angle @xmath216 this limit is reached at zero frequency .
but at angles close to @xmath216 the polarization can attain the low frequency plateau at physically meaningful frequencies and can be as high as almost @xmath243 . as it is clear from eqs .
( [ eq : jhighlimit ] ) and ( [ eq : jlowlimit ] ) , and fig .
( [ fig : jitpolarization ] ) that the degree of polarization does not depend on the spectral index of turbulence at low frequencies and increases with it at high frequencies
. the higher value of the spectral index corresponds to the turbulence when more energy is concentrated at larger scales of turbulence .
this means that the turbulence with smaller scale gives less polarized radiation at high frequencies .
the spectral power of jitter radiation also depends on the observation angle .
it is convenient to plot the spectral energy distribution normalized to the total averaged intensity given by eq .
( [ eq : avinten ] ) : @xmath244 the result is presented in fig . [
fig : totalpowerjitter53 ] .
the form of the spectrum does not change at large frequencies but slightly decreases with the angle .
it can be shown that the high frequency slope is determined by the spectral index of turbulence . indeed , in accordance with eq .
( [ eq : psihigh ] ) , eq .
( [ eq : qrjit ] ) gives @xmath245 at low frequencies , the form of the spectrum depends on the angle . in the limit of the small frequencies the behaviour of the function @xmath246
is well described by the following expression : @xmath247 where a common constant is omitted and @xmath248 . from this expression
one can see that spectral power tends to a constant .
it should be noted that at angles smaller than @xmath249 the function tends to the constant from below , whereas at larger angles it tends to the same constant from above . at @xmath230
the function behaves as @xmath250 .
the maximum of the spectral energy distribution is around @xmath238 .
taking into account a prefactor omitted in eq .
( [ eq : assymp ] ) one can show that at small frequencies the function @xmath246 grows with @xmath228 as it can be seen from fig .
[ fig : totalpowerjitter ] .
the degree of polarization of the synchrotron radiation is shown in fig .
[ fig : synpolarization ] .
for the same reason as in the case of the jitter radiation , the polarization is zero at the observation angle @xmath251 and increases with the observation angle .
the curve indicated as homogeneous b presents the case of radiation of an electron with the pitch - angle @xmath216 in the homogeneous magnetic field .
the polarization for the case of the distributions of the magnetic field strength @xmath203 , @xmath204 , and @xmath205 are shown by solid , dashed , and dotted curves , respectively .
one can see that for all angles the polarization grows with frequency and tends to a constant at small frequencies . in the case of homogeneous b
this constant equals @xmath243 .
as expected , at large frequencies the polarization is smaller for broader distributions of the magnetic field strength .
[ fig : polangle ] shows the degree of polarization as a function of observation angle . at the characteristic frequency
the polarization can be as high as @xmath241 . note that the polarization increases with the observation angle faster at high frequencies . the spectral energy distribution , @xmath252 , for the case @xmath203 is presented in fig .
[ fig : totalpowersyn ] . in contrary to the polarization , it decreases with the observation angle .
this anticorrelation is seen from the comparison of the results shown in fig .
[ fig : synpolarization ] and [ fig : totalpowersynb ] .
indeed , the broader distributions of magnetic field strength correspond to smaller polarization degree but larger intensity .
the distribution @xmath204 gives a slower decrease of intensity than in the case @xmath203 . in the case of @xmath205 , as shown in ref .
@xcite , the spectral energy distribution falls down as a power - law distribution . . in fig .
[ fig : comparison ] we compare the polarization degrees of the jitter and synchrotron radiation for different observation angles . at all angles and frequencies ,
the monoenergetic distribution of electrons produces more polarized radiation in the synchrotron than in the jitter regime .
it can also be seen in fig .
( [ fig : polangle ] ) where the low - frequency limit given by eq .
( [ eq : jlowlimit ] ) is shown by dashed line .
note that this feature of polarization of radiation by monoenergetic electrons , can not be generalized for an arbitrary distribution .
as it is shown in the next section the jitter radiation can be more polarized for certain electron distributions .
( [ eq : qrjit ] ) and ( [ eq : pqr ] ) allow calculations of the radiation properties for arbitrary distributions of electrons .
an important case is the power - law energy distribution of electrons .
if one takes into account that the geometry of turbulent magnetic fields discussed in this paper can be realized in the shock waves where the particles are accelerated typically with a power - law distribution , the consideration of power - law distribution of electrons is natural . in this section
we derive the formulas for the polarization of jitter radiation for the power - law distributions of electrons and compare them with the expressions for the synchrotron radiation obtained in ref .
@xcite . for the power - law distribution over the lorentz factor of electrons @xmath138 ,
@xmath253 the polarization tensor is @xmath254 where @xmath255 it should be noted that in the case of a power - law electron energy distribution the dependence of the power spectrum of the jitter radiation on frequency is identical to the synchrotron spectrum , namely , @xmath256 . introducing the spectral index of radiation @xmath257 , the degree of polarization of the jitter radiation is @xmath258 the calculation of the integrals gives @xmath259 note this expression coincides with the formula given by eq .
( [ eq : jhighlimit ] ) for the high - frequency limit in the case of monoenergetic electron distribution .
however , contrary to eq .
( [ eq : jhighlimit ] ) , this expression formally does not depend on the spectrum of the magnetic field turbulence . in the derivation of eq .
[ eq : jitpowpol ] we have neglected the low - energy cut - off of the electron distribution @xmath260 , assuming @xmath261 . for the non - zero value of @xmath260 , in the limit @xmath262 , where @xmath3 is the characteristic frequency of the synchrotron radiation corresponding to the lorentz factor @xmath260 , one can obtain the correction terms to the numerator and denominator in eq .
( [ eq : plawpol ] ) .
specifically , in the case of the turbulent spectrum given by eq .
( [ eq : jitturbspec ] ) we have @xmath263 at large frequencies , the correction terms , which depend on the spectral index of the turbulence @xmath228 , negligibly contribute to this expression , thus can be discarded .
the calculations of the degree of polarization of synchrotron radiation is @xcite @xmath264 where @xmath265.\end{aligned}\ ] ] here @xmath266 , and @xmath267 and @xmath268 are the legendre and associated legendre functions , respectively .
the degrees of polarization as a function of the observation angle given by eq .
( [ eq : jitpowpol ] ) for the jitter radiation ( solid lines ) and by eq .
( [ eq : synpowpol ] ) for the synchrotron radiation ( dashed lines ) are presented in fig .
[ fig : powerpolar ] . at spectral index of the radiation @xmath269
both expressions for the polarization are equal to @xmath270 at @xmath271 the polarization of the synchrotron radiation is higher . at @xmath272 the polarization of the jitter radiation becomes larger at all observation angles .
in this paper , the polarization properties of the radiation produced by isotropically distributed electrons in a _ turbulent _ magnetic field with directions strictly parallel to the plane ( so - called slab geometry ) have been studied .
we consider two extreme cases of the small and large turbulent scales . in the large - scale turbulent magnetic field
ultrarelativistic electrons radiate in the regular synchrotron regime .
the geometry of the field affects insignificantly the spectral energy distribution of radiation for a given turbulence spectrum .
the intensity observed at different observation angles differs within a factor of two ( see fig . [
fig : totalpowersyn ] ) .
the polarization is more sensitive to the observation angle .
it changes from @xmath273 , when the magnetic field plane is observed face - on to higher than @xmath274 when the plane is observed edge - on ( fig .
[ fig : synpolarization ] ) . both the intensity and the polarization are sensitive to the distributions over the magnetic field strength ( figs .
[ fig : totalpowersynb ] and [ fig : synpolarization ] ) . at high frequencies
the radiation spectrum in the cutoff region falls down slower in the case of broader field distribution . at the same time
the radiation becomes less polarized in turbulent field with a broader distribution . in a small - scale turbulent magnetic field ,
the properties of radiation of electrons are substantially different from the properties of the synchrotron radiation .
namely , if the characteristic length of the turbulence @xmath0 is smaller than the non - relativistic larmor radius @xmath275 , electrons emit in the jitter radiation regime .
the jitter radiation is determined by the scale of turbulence and , therefore , by definition , occurs only in the turbulent media . in the slab geometry of turbulent magnetic field , which can be generated in the relativistic shock waves , e.g. by weibel instability , we derived analytical formulae presented in eqs .
( [ eq : jittensor ] and [ eq : qrjit ] ) in the tensor form .
we derived also the spectral energy distribution of the jitter radiation field as a function of the observation angle @xmath46 . after averaging over @xmath46
, it naturally leads to the results derived in ref .
@xcite in the case of isotropic turbulence .
the jitter radiation has distinct spectral features .
the maximum of the spectral energy distribution is achieved at @xmath238 which is shifted @xmath276 times towards higher frequencies compared to the position of the maximum of the synchrotron radiation . at high frequencies
the spectrum has a power - law form ; the slope depends on the spectrum of the magnetic turbulence ( see eq .
( [ eq : jhighpower ] ) ) . at low frequencies ,
it is described by eq .
( [ eq : assymp ] ) which tends to a constant . as in the case of synchrotron radiation ,
the jitter radiation is not polarized when the magnetic field plane is observed face - on
. it grows with increase of the angle from this direction . in general , the polarization of the jitter and synchrotron radiations have similar properties . in both regimes , it increases with the frequency and the observation angle .
but they are different in details . in the case of the monoenergetic distribution of electrons ,
the polarization of the synchrotron radiation is higher than the polarization of the jitter radiation at all observation angles and frequencies .
however , for the power - law distribution of elections the polarization of the jitter radiation can be higher . | we study the polarization properties of the jitter and synchrotron radiation produced by electrons in highly turbulent anisotropic magnetic fields .
the net polarization is provided by the geometry of the magnetic field the directions of which are parallel to a certain plane .
such conditions may appear in the relativistic shocks during the amplification of the magnetic field through the so - called weibel instability . while the polarization properties of the jitter radiation allows extraction of direct information on the turbulence spectrum as well as the geometry of magnetic field , the polarization of the synchrotron radiation reflects the distribution of the magnetic field over its strength .
for the isotropic distribution of monoenergetic electrons , we found that the degree of polarization of the synchrotron radiation is larger than the polarization of the jitter radiation .
for the power - law energy distribution of electrons the relation between the degree of polarization of synchrotron and jitter radiation depends on the spectral index of the distribution . |
BAY VILLAGE, Ohio – Actor and comedian Drew Carey offered to help Bay Village police find the perpetrators behind a prank played on an autistic teenager.
Via Twitter, Carey said that if the police want to start a reward fund to find the people who organized the prank, he would donate $10,000 to it.
Carey, a Cleveland native, followed up by saying if police found the pranksters without a reward, he would donate to Autism Speaks.
The 14-year-old boy's mother found a cell phone video of several Bay High School students dumping a bucket filled with urine and feces on her son in a twisted rendition of the ALS Ice Bucket Challenge.
The video was posted on Instagram.
Bay Village Police Chief Mark Spaetzel called the prank "heinous," and said charges would be brought as soon as police identify the teens who organized the prank.
Bay Village School District faculty sent a letter to students and parents this week informing them of the situation and saying the actions of the teenagers in the video do not reflect the majority of their student body.
The high school organized a vigil for the teen prior to a Friday night football game.
If the Bay Village PD wants to start a reward fund to find who did this, contact me. I'll donate $10k. http://t.co/ugqeLbu5ob — Drew Carey (@DrewFromTV) September 6, 2014 ||||| CLEVELAND, Ohio — Drew Carey's offer to start a reward fund to find the people responsible for a prank on an autistic Bay Village teen is getting some additional backing from Jenny McCarthy and her husband, Donnie Wahlberg.
The actress, comedian and former co-host of "The View" tweeted Sunday night that she will contribute $10,000 to a fund to help Bay Village police catch those responsible for a cruel prank involving the ALS Ice Bucket Challenge.
Carey already had pledged $10,000:
I'm joining Drew Carey's 10K Reward to Find Perpetrators Behind Horrible ALS Bucket Prank. Now it's 20k! #justice — Jenny McCarthy (@JennyMcCarthy) September 8, 2014
McCarthy's husband, an actor and former member of the boy band New Kids on the Block, tweeted later that he also is pledging $10,000. Former talk show host Montel Williams says he plans to contribute.
Carey responded to McCarthy with his own tweet saying "yay!" and also said that on Monday he will start an online effort to raise more money:
I’ll be working on a kickstarter or gofundme or something on Monday RT @TheBardockObama @DrewFromTV how can I add $5,000.00 to the fund? — Drew Carey (@DrewFromTV) September 8, 2014
Last week, a video showed Bay High students dumping urine and feces on a 14-year-old special-needs student, telling him it was part of the ALS Ice Bucket Challenge. The video was posted on Instagram.
Bay Village police are investigating the incident and are receiving cooperation from the school district. The prank did not occur on school grounds or during school hours, police said, although they are unsure where it took place.
A news release from the city says anyone who wants to make a personal donation to the family of the victim should contact the law offices of Valore & Gordillo at 440-333-7330. | – Drew Carey has offered $10,000 to help find a group of Cleveland-area teenagers who humiliated an autistic boy with their twisted take on the ALS ice bucket challenge. The 14-year-old's mother contacted police after discovering that the group of teens had used the boy's phone to record a video of them dumping a bucket of urine, feces, and spit on him and telling him it was part of the challenge, reports the Cleveland Plain Dealer. Comedian and Price Is Right host Carey, a Cleveland native, says that if police find the teens behind the "horrendous" prank themselves and the reward isn't needed, he will give the money to the Autism Speaks group instead, Mashable reports. The reward more than tripled last night as more celebrities followed Carey's lead, another Plain Dealer story reports. After ex-View host Jenny McCarthy pledged $10,000, her new husband Donnie Wahlberg offered another $10,000, and Montel Williams also promised to contribute. |
it appears that many perovskite manganites , when doped by holes up to the level corresponding to the formal valence of mn @xmath6@xmath7 , exhibit very specific properties , inherent to only this particular hole concentration and different from other doping regimes .
the compounds are insulating and at certain temperature range ( typically at low temperatures ) form rather peculiar magnetic ordering consisting of ferromagnetic ( fm ) zigzag chains , coupled antiferromagnetically
[ fig.chains ] . in the case of three - dimensional manganites ,
this is the well known ce - type antiferromagnetic ( afm ) ordering , which was proposed long ago by goodenough,@xcite and first observed by wollan and koehler in la@xmath8ca@xmath9mno@xmath10 near @xmath11@xmath12@xmath13.@xcite the zigzag afm ordering appeared to be a more generic and was observed recently in a number of systems , including the layered manganite la@xmath14sr@xmath15mno@xmath16 ( refs . ) and the double - layer manganite lasr@xmath17mn@xmath17o@xmath18 ( ref . ) .
the magnetic ordering is accompanied by the orbital ordering,@xcite which is also shown in fig . [ fig.chains ] .
the insulating zigzag afm state can be transformed into the metallic fm state by applying an external magnetic field.@xcite other examples of such compounds and detailed description of their properties can be found in the review articles.@xcite the systems are usually referred to as the charge ordered manganites , implying that the homogeneous state of mn@xmath19 ions in the lattice is unstable towards the charge disproportionation amongst two alternately aligned types of sites : @xmath20mn@xmath19@xmath21mn@xmath22@xmath6mn@xmath23 .
the electronic configurations of the mn@xmath22 and mn@xmath23 ions are @xmath24 and @xmath25 , respectively .
thus , the @xmath26 orbitals are half - filled in both cases , giving rise to the afm superexchange interaction between nearest neighbors . due to the strong hund s rule coubling ,
the @xmath5 electron and three @xmath26 electrons at the mn@xmath23 site are aligned ferromagnetically .
it is assumed that the @xmath5 electron is mobile and can hop to the neighboring mn@xmath22 by forming the fm double - exchange ( de ) coupling in a certain number of mn@xmath23-mn@xmath22 bonds.@xcite the occupied @xmath5 orbitals are ordered in the direction of these bonds so to maximize the de coupling .
this is the basic physical idea underlying goodenough s conjecture for the ce - type afm ordering.@xcite the picture had no solid justification and for many years remained to be on the level of a hypothesis .
only very recently it was realized by several authors that , at least at very low temperatures , the basic proporties of the charge ordered manganites can be understood exclusively from the viewpoint of the de physics.@xcite due to the strong hund s rule coupling , the mn ions form a high - spin state in manganites .
therefore , the intraatomic exchange splitting is large .
if it is much larger than the kinetic hoppings between nearest - neighbor @xmath5 orbitals , the minority - spin @xmath5 states can be projected out of the problem . in the case of afm ordering , this will suppress all kinetic hoppings between mn - sites with opposite directions of the spin magnetic moments . in the following
we will refer to this picture as the de limit .
thus , the ce phase in the de limit will be effectively devided into the one - dimensional zigzag chains
. this will create two geometrically different types of mn - sites : the so - called bridge sites @xmath27 and @xmath28 , and the corner sites @xmath29 and @xmath30 see fig . [ fig.chains ] .
however , the difference is not necessarily related with the integer change of atomic charges when going from one type of mn - sites to another . in the other words , the bridge sites are not necessarily occupied by the mn@xmath23 ions and the corner sites - by the mn@xmath22 ions .
the two - fold degeneracy of @xmath5 levels plays a very important role in the problem .
the isolated chain behaves as a band insulator .
the only occupied @xmath5 orbitals at the sites @xmath27 and @xmath28 are @xmath31@xmath32@xmath33 and @xmath34@xmath32@xmath33 , respectively , that is exactly the orbital ordering shown in fig .
[ fig.chains ] . in our recent letter ( ref
we argued that the local stability of the zigzag afm state can be explained by the anisotropy of the interatomic magnetic interactions in the de limit , whereas the charge ordering itself may be irrelevant to the problem . in the present paper we will further ellaborate this de picture . in sec .
[ sec : tbmodel ] we will derive the tight - binding ( tb ) hamiltonian for the zigzag chain , discuss basic features of the electronic structure , and obtain several useful expressions for matrix elements of the green function and for the wavefunctions . in sec .
[ sec : exchanges ] we will derive analytical expressions for magnetic interactions in the de limit and address the problem of local and global stability of the zigzag afm ordering .
these two sections will also clarify the main results published in ref . .
sec : optics ] we will turn to the optical properties of the zigzag chain and discuss possible implications for the resonant x - ray scattering near mn @xmath4-absorption edge.@xcite in sec . [ sec : lsda ] we will discuss validity of the tb picture by comparing it with results of first - principles band structure calculations in the local - spin - density approximation ( lsda ) . a brief summary will be given in sec .
[ sec : summary ] .
we would like to emphasize from the very beginning that we treat the minimal model which can be proposed for perovskite manganites .
the model is based on the de physics and takes into account the two - fold degeneracy of the @xmath5 levels .
the combination of these two ingredients represents a necessary basis for the analysis of manganite compounds .
the main purspose of this paper is to argue that such a simple degenerate de model provides a very consistent description for the low - temperature properties of the ce state in manganites . at present
it is not clear whether the same de model will be sufficient in the high - temperature regime . in sec .
[ sec : summary ] , we will collect some remarks on this matter .
we are planning this paper as the first part in the series of two publications dealing with the electronic structure and properties of the charge ordered manganites .
the present work contains mainly the model analysis .
results of the first - principles band structure calculations and the structure optimization will be presented in ref . .
the first reports about this activity can be found in refs . .
in fact , the basic idea of the de picture discussed in ref . was inspired by lsda calculations of the zigzag afm phase in layered manganites ( ref . ) .
the basic translation properties of the single zigzag chain are given by the symmetry operation @xmath35@xmath12@xmath36 , which combines the 180@xmath37 rotation around the axis @xmath38 $ ] , @xmath39 , with the translation @xmath40@xmath12@xmath41 $ ] connecting the sites @xmath27 and @xmath28 .
therefore , it is convenient to choose the atomic bases at different sites in such a form that they can be transformed to each other by the operation @xmath42@xmath12@xmath43 , where @xmath44 is the integer number of translations separating two sites . for the @xmath5 states this can be achieved by adopting the following basis orbitals : @xmath45 at the site @xmath27 ,
@xmath46 at the site @xmath29 , @xmath47 at the site @xmath28 , and @xmath48 at the site @xmath30 , which are periodically repeated to the whole chain .
we assume that the kinetic hoppings between nearest - neighbor @xmath5 orbitals are of the @xmath49 type and can be parameterized in accordance with the slater - koster rules.@xcite in the above basis , this yields the following nonvanishing matrix elements between sites @xmath27 , @xmath29 and @xmath28 of the chain 1 in fig .
[ fig.chains ] : @xmath50 in the notation @xmath51 , @xmath44 and @xmath52 stand for the site indices , @xmath53 and @xmath54 - for the orbital ( basis ) indices .
the absolute value of the @xmath49 two - center integral is used as the energy unit .
the atomic orbitals @xmath55 of the sites @xmath27 and @xmath28 are inert and do not participate in the hoppings . in the local representation given by eqs .
( [ eqn : basisa])-([eqn : basisbb ] ) , any translation @xmath56 in the real space will transform the matrix of kinetic hoppings to itself .
therefore , we can apply the generalized bloch transformation @xmath57 , @xmath32@xmath58@xmath59@xmath60@xmath59@xmath58 , to the de hamiltonian in the real space @xmath61@xmath12@xmath62@xmath32@xmath63 .
this leads to the following @xmath0@xmath1@xmath0 hamiltonian in the reciprocal space , in the basis of generalized bloch orbitals of @xmath64 , @xmath65 and @xmath66 type : @xmath67 the parameter @xmath68@xmath69@xmath70 was added in order to simulate the charge disproportionation between the sites @xmath27(@xmath28 ) and @xmath29(@xmath30 ) .
the hamiltonian has the following eigenvalues : + @xmath71@xmath12@xmath72@xmath73@xmath74 , the bonding ( @xmath32 ) and antibonding ( @xmath6 ) bands , and + @xmath75@xmath12@xmath68 , a nonbonding band , which has nonvanishing weight only at the sites @xmath29 and @xmath30 .
all three bands are separated by energy gaps .
thus , if there is exactly one electron per two sites @xmath27 and @xmath29 , the low - lying bonding band is fully occupied and the system behaves as an one - dimensional band insulator .
therefore , the insulating behavior of the so - called charge ordered manganites may not be related with the charge ordering .
rather , it may be a consequence of the peculiar zigzag afm ordering , combined with the de physics .
corresponding densities of states are shown in fig .
[ fig.tbdos ] .
( details of calculations are given in appendix [ subsec : dos ] . ) as expected for the one - dimensional system , the densities of states diverge at the band edges .
since only @xmath31@xmath32@xmath33 ( @xmath34@xmath32@xmath33 ) state are occupied at the sites @xmath27(@xmath28 ) , the zigzag afm ordering in the degenerate de model automatically leads to the orbital ordering shown in fig .
[ fig.chains ] . in the reciprocal space ,
the green function for the hamiltonian ( [ eqn : hamiltonian ] ) is given by @xmath76@xmath12@xmath77@xmath32@xmath78@xmath6@xmath79^{-1}$ ] , where @xmath80 is a positive infinitesimal .
it has the following matrix elements : @xmath81 @xmath82 @xmath83 @xmath84 @xmath85 @xmath86 the green function elements in the real space are obtained by the fourier transformation : @xmath87 where @xmath88 and @xmath89 correspond to either @xmath27 or @xmath29 in eqs .
( [ eqn : g11aa])-([eqn : g12bb ] ) .
this is the local representation for the green function , meaning that the form of the basis orbitals @xmath53 and @xmath54 varies from site to site as prescribed by eqs .
( [ eqn : basisa])-([eqn : basisbb ] ) .
we search the wave - functions of the hamiltonian ( [ eqn : hamiltonian ] ) in the form : @xmath90 by substituting this expression into the secular equation @xmath91@xmath92@xmath12@xmath70 , the wavefunctions can be found as follows . for the bonding and antibonding states
@xmath71 we obtain : @xmath93@xmath12@xmath32@xmath94 and @xmath95@xmath12@xmath96 .
corresponding wave - functions are given by @xmath97 at the site @xmath27 , and @xmath98 at the site @xmath29 .
for the nonbonding states @xmath75@xmath12@xmath68 we have : @xmath99@xmath12@xmath100 and @xmath101@xmath12@xmath102 .
then , the wave - functions will have nonvanishing elements only at the corner sites .
they are given by @xmath103 the wave - functions at the sites @xmath28(@xmath30 ) are related with the ones at the site @xmath27(@xmath29 ) by the transformation : @xmath104
we consider small nonuniform rotations of the spin magnetic moments on a discrete lattice , characterized by the angles @xmath105 .
if @xmath106 is the direction of the spin magnetic moment at the site @xmath107 corresponding to an equilibrium , the new direction is given by @xmath108@xmath12@xmath106@xmath6@xmath109 , where @xmath110 - \frac{1}{2 } ( \mbox{\boldmath$\delta\varphi$}_{\it i})^2 { \bf e}^0_{\it i}. \label{eqn : rotations}\ ] ] in the second order of @xmath105 , the total energy change takes isotropic heisenberg form ( ref .
, see also appendix [ apndx ] ) : @xmath111 and the parameters @xmath112 can be expressed through the second derivatives of the total energy with respect to the angles @xmath105.@xcite in the afm state we have @xmath106@xmath12@xmath113 ( @xmath106@xmath12@xmath32@xmath113 ) if the sites @xmath107 and @xmath114 belong the same ( different ) sublattices . following the work by de gennes ( ref .
) we assume that the total energy consists of two contributions : @xmath115$]@xmath12@xmath116$]@xmath6@xmath117 $ ] , where @xmath116 $ ] is the kinetic ( double - exchange ) energy of the @xmath5 electrons , and @xmath117$]@xmath12@xmath32@xmath118 is the energy of afm superexchange interactions between nearest neighbors @xmath119 . in practice ,
the coupling @xmath120@xmath121 is associated with the localized @xmath26 spins , and may also account for some interactions amongst @xmath5 electrons beyond the de limit.@xcite in this model , the nearest - neighbor magnetic interaction is the sum of generally anisotropic de coupling @xmath122 ( the second derivative of the kinetic energy of the @xmath5 electrons ) and the isotropic superexchange coupling : @xmath123@xmath12@xmath122@xmath6@xmath120 .
parameters @xmath124 depend on the magnetic state in which they are calculated and define conditions of the local stability of this magnetic state . the magnetic ordering is stabilized globally if it has the lowest energy amongst all possible locally stable magnetic states . in other words , this is the magnetic ground state of the system . although the _ total energy change _ near @xmath125 has the form of the heisenberg model
( [ eqn : heisenberg ] ) , it does not necessary mean that the same expression is applicable for the _ absolute value of the total energy _ in the point @xmath125 , i.e. generally it does not hold @xmath126$]@xmath12@xmath127@xmath128 .
one example illustrating such a violation is the de model , where only interatomic de interactions in the fm bonds contribute to the kinetic energy.@xcite the total energy in the de model can still be expressed in terms of @xmath112 , but the form of this expression will be different from the heisenberg model . in the de limit , magnetic interactions between nearest neighbors located in the same chain , @xmath129 ( see fig . [ fig.chains ] for notations ) ,
can be calculated as:@xcite @xmath130 using matrix elements of the green function , eqs .
( [ eqn : g11ab ] ) and ( [ eqn : g12ab ] ) , and the kinetic hoppings , eq .
( [ eqn : hoppings ] ) , we obtain : @xmath131 the interaction @xmath129 is always positive and responsible for the fm coupling within the chain .
the numerical value for @xmath68@xmath12@xmath70 is @xmath132@xmath133@xmath134 .
the charge disproportionation will reduce @xmath129 .
indeed , the former is defined as the difference of atomic populations at the sites @xmath27 and @xmath29 , @xmath135@xmath12@xmath136@xmath32@xmath137 , which yields:@xcite @xmath138 the dependence @xmath129 versus @xmath135 is shown in fig .
[ fig.ja1b1 ] . as @xmath135 increases
, @xmath129 decreases .
therefore , the charge ordering suppresses the fm de coupling within the chain and plays a destructive role in the magnetic stability of the ce - type afm ordering . in the de limit
, magnetic interactions between antiferromagnetically coupled atoms are given by the following expression:@xcite @xmath140 where @xmath141 is the trace over the orbital indices .
( [ eqn : de_afm ] ) , the sites @xmath107 and @xmath142 belong to one zigzag chain , and the sites @xmath114 and @xmath143 belong to another zigzag chain , different from the first one .
if @xmath107@xmath12@xmath144 and @xmath114@xmath12@xmath145 for the geometry shown in fig . [ fig.chains ] , we will have the following six nonvanishing contributions to the exchange coupling ( [ eqn : de_afm ] ) : @xmath146 @xmath147 @xmath148 @xmath149 @xmath150 @xmath151 the nonbonding @xmath152@xmath32@xmath153 ( @xmath154@xmath32@xmath153 ) orbitals of @xmath27 ( @xmath28 ) sites are unoccupied and can be dropped in the analysis of magnetic interactions of the single zigzag chain . however , they contribute to the inter - chain interactions . the corresponding element of the green function is @xmath155@xmath12@xmath156@xmath32@xmath157@xmath6@xmath158 , where @xmath159 is the energy position of the atomic @xmath152@xmath32@xmath153 ( @xmath154@xmath32@xmath153 ) levels .
the remaining elements of the green function listed above are given by eqs .
( [ eqn : g11aa])-([eqn : g22bb ] ) .
corresponding hopping matrix elements in the local coordinate frame ( [ eqn : basisa])-([eqn : basisbb ] ) are @xmath160@xmath12@xmath161@xmath12@xmath162 , @xmath163@xmath12@xmath32@xmath164@xmath12@xmath32@xmath165@xmath12@xmath166 , and @xmath167@xmath12@xmath32@xmath168 .
then , noting that @xmath169@xmath12@xmath170 , we obtain the following expression : @xmath171 the numerical value of this integral for @xmath159@xmath12@xmath68@xmath12@xmath70 is @xmath172@xmath133@xmath173 , which is significantly smaller than the value of the intra - chain integral @xmath132 .
such an anisotropy of magnetic interactions in the de limit readily explain the local stability of the ce - type afm ordering in the @xmath11-@xmath139 plane . indeed , by combining @xmath129 and @xmath174 with the isotropic superexchange interaction @xmath120
, we obtain the following condition of the local stability : @xmath175 i.e. , we require the total coupling @xmath122@xmath6@xmath120 to be fm within the chain and afm between the chains . since @xmath172@xmath176@xmath132 , this condition can be easily satisfied . in the two - dimensional case ,
this is the only condition of the local stability of the zigzag afm ordering . in the three - dimensional case , the inequality ( [ eqn : ls.2d ] )
shall be combined with remaining two conditions of the local stability in the bonds @xmath144@xmath32@xmath177 and @xmath178@xmath32@xmath179 connecting neighboring @xmath11-@xmath139 planes
[ fig.chains ] . in the local basis of atomic orbitals ( [ eqn : basisa])-([eqn : basisbb ] ) ,
the kinetic hoppings between sites @xmath144 and @xmath177 , along the @xmath180 direction , are @xmath181@xmath12@xmath162 , @xmath182@xmath12@xmath183@xmath12@xmath166 , and @xmath184@xmath12@xmath168 .
then , applying eq .
( [ eqn : de_afm ] ) for @xmath107@xmath12@xmath144 and @xmath114@xmath12@xmath177 , and noting that @xmath185@xmath12@xmath186 , we obtain:@xcite @xmath187 the numerical value of this integral for @xmath159@xmath12@xmath68@xmath12@xmath70 is @xmath188@xmath133@xmath189 . for the @xmath29-sites ,
the only nonvanishing hopping along the @xmath180-direction is @xmath190@xmath12@xmath191 .
then , applying eq .
( [ eqn : de_afm ] ) for @xmath107@xmath12@xmath178 and @xmath114@xmath12@xmath179 , and noting that @xmath170@xmath12@xmath192 , we obtain : @xmath193 for @xmath159@xmath12@xmath68@xmath12@xmath70 , @xmath194 can be estimated as @xmath195@xmath133@xmath196 , which is different from the value reported in ref . .
the reason is the following . in ref . , we employed a different basis of atomic orbitals at the sites @xmath29 and @xmath30 . in that basis , the green function @xmath170 has off - diagonal elements with respect to the orbital indices , which have been neglected in the analysis of magnetic interactions in ref . .
the new values of the exchange integrals take into account these terms .
the correction appears to be small for the in - plane exchange interaction @xmath172 and modifies it only in the fourth digit after the comma .
however , the change of the inter - plane exchange interaction @xmath195 appears to be more significant . with this new value of @xmath195 , the main statement of ref . appears to be even stronger . if @xmath120 satisfies the condition @xmath197 the fm coupling is stabilized in the bond @xmath144-@xmath178 , and the afm coupling is stabilized in the bonds @xmath144-@xmath145 , @xmath144-@xmath177 and @xmath178-@xmath179 .
since @xmath195@xmath198@xmath199@xmath176@xmath132 , appearance of the three - dimensional ce - type afm ordering can be fully explained by the anisotropy of magnetic interactions in the de limit .
we will call eq .
( [ eqn : ls.3d.hard ] ) the hard condition of the local stability .
similar to ref . , we can also consider the ce - type afm ordering in the regime : @xmath200 when the total coupling in the bond @xmath178-@xmath179 is ferromagnetic . even in this case , the ce - type afm ordering may remain stable due to the joint effect of magnetic interactions in the bonds @xmath144-@xmath177 , @xmath144-@xmath178 and @xmath144-@xmath145 .
we will call eq .
( [ eqn : ls.3d.soft ] ) the soft condition of the local stability . in ref .
we argued that in the de limit the kinetic energy for a collinear magnetic state m is related with the interatomic de coupling parameter in the fm bonds , @xmath201 , as @xmath202@xmath12@xmath32@xmath203 , where @xmath204 is the number of fm bonds .
the superexchange energy is given by @xmath205@xmath12@xmath32@xmath206@xmath32@xmath207 , where @xmath208 is the number of afm bonds .
this represents the connection between the parameters @xmath209 and the total energy of the de model .
let us consider the three - dimensional case . for the hole concentration
@xmath11@xmath12@xmath13 we can expect three possibilities : the fm ordering ( @xmath210@xmath12@xmath211 , @xmath204@xmath12@xmath212 , and @xmath208@xmath12@xmath70 ) , the a - type afm ordering ( @xmath210@xmath12@xmath213 , @xmath204@xmath12@xmath214 , and @xmath208@xmath12@xmath20 ) , and the ce - type afm ordering ( @xmath210@xmath12@xmath215,@xmath204@xmath12@xmath20 , and @xmath208@xmath12@xmath214 ) .
the chain - like c - type afm ordering is unstable for @xmath11@xmath12@xmath13,@xcite and can be excluded from the analysis .
corresponding total energies are given by : @xmath216@xmath12@xmath32@xmath217@xmath32@xmath218 , @xmath219@xmath12@xmath220@xmath221@xmath32@xmath120 , and @xmath222@xmath12@xmath32@xmath223@xmath6@xmath120 .
conditions of the local stability of the fm and a - type afm states are @xmath224@xmath176@xmath225 and @xmath226@xmath176@xmath224@xmath227 , respectively , where @xmath226 is the nearest - neighbor exchange interaction between antiferromagnetically coupled atoms in the de limit .
hard and soft conditions of the local stability of the ce - type afm ordering are given by eqs .
( [ eqn : ls.3d.hard ] ) and ( [ eqn : ls.3d.soft ] ) , respectively .
numerical values of the exchange integrals for @xmath11@xmath12@xmath13 and @xmath68@xmath12@xmath159@xmath12@xmath70 are @xmath225@xmath133@xmath228 , @xmath221@xmath229@xmath230 and @xmath226@xmath231@xmath232.@xcite corresponding phase diagram is shown in fig .
[ fig.local-global ] , where we plot the total energies for each magnetic state on the interval inside of which this magnetic state is locally stable
. we also added the data for two canted spin states which may exist for @xmath11@xmath12@xmath13 .
these solutions of the de model can be regarded as intermediate states between : + ( 1 ) the fm and a - type afm ordering ( the canted spin state of the fa type ) ; + ( 2 ) the a- and g - type afm ordering ( the canted spin state of the ag type).@xcite from fig .
[ fig.local-global ] we can conclude that the ce - type afm ordering may coexist only with the a - type afm ordering and the canted spin ordering of the ag type . the fm ordering and the canted spin ordering of the fa type may develop only for smaller @xmath224 , when the ce - type afm ordering is already unstable .
if @xmath224@xmath69@xmath233 ( the crossing point of ce and a total energy curves ) , the ce - type afm state has the lowest energy amongst the states ce , a and ag , and is the magnetic ground state of the system . in the two - dimensional case ,
the phase diagram is very simple : the total energy of the zigzag afm state ( @xmath204@xmath12@xmath20 , @xmath208@xmath12@xmath20 ) , @xmath234@xmath12@xmath32@xmath223 , shall be compared with the total energy of the two - dimensional fm state ( @xmath204@xmath12@xmath214 , @xmath208@xmath12@xmath70 ) , @xmath235@xmath12@xmath32@xmath236@xmath32@xmath237 , where @xmath238@xmath133@xmath230.@xcite conditions of the local stability are : @xmath224@xmath176@xmath238 for the two - dimensional fm ordering , and eq .
( [ eqn : ls.2d ] ) for the zigzag afm ordering .
two states coexist in the interval @xmath174@xmath176@xmath224@xmath176@xmath238 . if @xmath224@xmath69@xmath233 , the zigzag afm state has lower energy than the fm state and vice versa .
we assume that the jahn - teller distortion ( jtd ) results in the shift of atomic @xmath154@xmath32@xmath153/@xmath31@xmath32@xmath33 ( @xmath152@xmath32@xmath153/@xmath34@xmath32@xmath33 ) levels of the @xmath27 ( @xmath28 ) sites by @xmath73@xmath239 .
this is equivalent to the following choice of the parameters of our original hamiltonian : @xmath159@xmath12@xmath240 and @xmath68@xmath241@xmath239 , i.e. in addition to the local splitting at the @xmath27 ( @xmath28 ) sites , we shift all the states upwards by @xmath239 .
obviously , the constant shift does not affect the magnetic interactions .
thus , the jtd in such a picture will be accompanied by a charge disproportionation , and suppress the fm de coupling within the chain ( see fig .
[ fig.ja1b1 ] ) .
this is , in principle , a negative consequence which lowers the upper boundary of the local stability of the zigzag afm ordering .
nevertheless , for relatively small distortions , the change of @xmath129 is also expected to be small .
the effect of @xmath240 on the interatomic interactions in the afm bonds @xmath144-@xmath145 , @xmath144-@xmath177 and @xmath178-@xmath179 is more dramatic . the results are summarized in fig . [ fig.jt.exchange ] .
in order to evaluate the magnitude of the oxygen displacement which results in the splitting @xmath240 , we consider the following procedure:@xcite ( i ) we start with a general tb hamiltonian on an undistorted cubic lattice , in the basis of mn(@xmath2 ) and o(@xmath242 ) orbitals interacting via nearest - neighbor @xmath243 hoppings , the distance - dependence of which is simulated by the harrison low : @xmath244@xmath245@xmath246 ; ( ii ) we switch on the jtd of the mno@xmath247 octahedra around the bridge sites , the @xmath248 mode,@xcite ( it is assumed that the total volume of the mno@xmath247 octahedron remains to be constant ) ; ( iii ) we project out the o(@xmath242 ) states .
this results in the on - site splitting of @xmath5 orbitals , @xmath240@xmath133@xmath249 ( in units of the effective @xmath49 two - center integral for the undistorted cubic lattice ) , where the oxygen displacement is described by the parameter @xmath250@xmath12@xmath251@xmath32@xmath252@xmath6@xmath253 , with @xmath254 ( @xmath255 ) being the long ( short ) mn - o bond length in the distorted mno@xmath247 octahedron .
then , the behavior of magnetic interactions shown in fig . [ fig.jt.exchange ] suggests that even a modest distortion @xmath250@xmath12@xmath256 ( @xmath240@xmath133@xmath257 , see also ref . ) may reduce the fm contribution to the afm bonds @xmath144-@xmath145 and @xmath178-@xmath179 by up to 20% , whereas the coupling in the fm bond @xmath144-@xmath178 remains practically unchanged .
therefore , the jtd significantly lowers the low boundary of the local stability for the zigzag afm ordering . as the result ,
the range of parameters @xmath224 which stabilize the zigzag afm ordering significantly widens .
in order to evaluate the optical conductivity tensor @xmath258 for the single zigzag chain we take the following steps . first , we include the mn(@xmath3 ) states in our model and evaluate their admixture into the eigenfunctions of hamiltonian ( [ eqn : hamiltonian ] ) using the simplest perturbation theory .
we assume that the main perturbation is caused by the kinetic hoppings between nearest - neighbor mn(@xmath3 ) and mn(@xmath2 ) orbitals.@xcite the hoppings are of the @xmath243 type and can be parameterized in accordance with slater - koster rules.@xcite it is further assumed that the energy splitting between the atomic @xmath3 and @xmath2 levels , @xmath259 , is much larger than the corresponding bandwidths , so that the band dispersion can be neglected in the perturbation theory expansion ( this is certainly a very crude approximation , especially for the @xmath3 band , the validity of which will be discussed in sec .
[ sec : lsda ] ) .
thus , the mixture of the mn(@xmath3 ) and mn(@xmath2 ) states will be controlled by the parameter @xmath260@xmath12@xmath261@xmath262@xmath259 , where @xmath261 is the @xmath3-@xmath2 two - center integral.@xcite then , by knowing distribution of the mn(@xmath3 ) and mn(@xmath2 ) states we can find matrix elements of the interband optical transitions @xmath263@xmath21@xmath75 and @xmath263@xmath21@xmath264 , and express them through the intra - atomic dipole @xmath3-@xmath2 matrix elements . finally , the optical conductivity can be calculated using the kubo formula . due to the one - dimensional character of the problem ,
the solution along this line can be carried out analytically .
for simplicity we will consider only the case of homogeneous charge distribution ( @xmath68@xmath12@xmath70 ) .
the simple tb picture considered in this section is of course very oversimplified and can not provide a good quantitative description .
however , it appears to be very useful in the analysis of symmetry properties and the structure of the conductivity tensor in terms of partial contributions from different sites of the system .
first , we consider the admixture of the @xmath3-orbitals @xmath265 and @xmath266 into the bonding and antibonding states of the hamiltonian ( [ eqn : hamiltonian ] ) . taking in to account the explicit form of the wavefunctions at the sites @xmath27 and @xmath28 given by eqs .
( [ eqn : wfpma ] ) and ( [ eqn : wfaabb ] ) , and considering the nearest - neighbor @xmath243 hoppings from the sites @xmath27 and @xmath28 to the site @xmath29 of the chain 1 in fig . [ fig.chains ] , we obtain the following corrections to the wavefunctions at the site @xmath29 , in the first order of @xmath260 : @xmath267 starting with the sites @xmath29 and @xmath30 and considering the hoppings onto the site @xmath27 , we obtain : @xmath268 similar analysis applied to the nonbonding state @xmath269 yields : @xmath270 since @xmath269 has nonvanishing elements only at the sites of @xmath29 and @xmath30 type and the kinetic @xmath2-@xmath3 hoppings are restricted by the nearest neighbors , the correction @xmath271 may exist only at the ( neighboring ) sites of @xmath27 type .
corresponding corrections at the sites @xmath28 and @xmath30 can be found using eq .
( [ eqn : wfaabb ] ) .
the nonvanishing intra - atomic dipole matrix elements obey the following rules:@xcite @xmath272@xmath32@xmath273@xmath274@xmath275@xmath32@xmath276@xmath198@xmath277 , @xmath278@xmath32@xmath273@xmath274@xmath279@xmath32@xmath280@xmath12@xmath32@xmath281 , and @xmath282@xmath32@xmath283@xmath274@xmath284@xmath282@xmath32@xmath285@xmath274@xmath286 .
then , using results of secs .
[ subsec : wavefunctions ] and [ subsec : mn.4p ] for @xmath68@xmath12@xmath70 , we obtain the following matrix elements : @xmath287 for the bonding - nonbonding transitions at the sites @xmath27 and @xmath28 ; @xmath288 for the bonding - nonbonding transitions at the sites @xmath29 and @xmath30 ; @xmath289 for the bonding - antibonding transitions at the sites @xmath27 and @xmath28 ; and @xmath290 for the bonding - antibonding transitions at the sites @xmath29 and @xmath30 . the inter - band optical conductivity tensor can be obtained using the kubo formula : @xmath291 where @xmath292@xmath12 @xmath11 , @xmath139 ; @xmath293 and @xmath294 stand for the initial state @xmath295@xmath12@xmath32 ; @xmath296 and @xmath297 stand for the final state @xmath298@xmath12@xmath70 or
@xmath6 .
we consider only site - diagonal contributions in eq .
( [ eqn : kubo ] ) .
the integral can be evaluated along the same line as for the local densities of states in appendix [ subsec : dos ] .
then , we obtain the following nonvanishing contributions to the conductivity tensor : @xmath299 at the sites @xmath27 and @xmath28 , where @xmath300 for the bonding - nonbonding transitions ( we drop the common multiplier @xmath301 ) , and @xmath302 for the bonding - antibonding transitions ; @xmath303 and @xmath304 at the sites @xmath29 and @xmath30 , where @xmath305 for the bonding - nonbonding transitions , and @xmath306 for the bonding - antibonding transitions .
the results are shown in fig .
[ fig.opt.tb ] .
the conductivity spectrum consists of two parts originating from the bonding - nonbonding and bonding - antibonding transitions , and spreading within the intervals @xmath191@xmath59@xmath307@xmath59@xmath308 and @xmath20@xmath59@xmath307@xmath59@xmath309 , respectively .
taking into account that a realistic estimate for the effective @xmath49 two - center integral is about 0.7 ev ( for the undistorted lattice , without buckling of mn - o - mn bonds),@xcite they roughly correspond to the energy ranges @xmath310@xmath59@xmath307@xmath59@xmath311 ev and @xmath312@xmath59@xmath307@xmath59@xmath313 ev .
we note that the components of the conductivity tensor associated with the bridge ( @xmath27,@xmath28 ) and the corner ( @xmath29,@xmath30 ) sites are characterized by different optical axes .
the tensors @xmath314 and @xmath315 are diagonal in the basis of cubic axes @xmath11@xmath12@xmath316 $ ] and @xmath139@xmath12@xmath317 $ ] shown in fig .
[ fig.chains ] . in this basis ,
each of the tensors has only one nonvanishing diagonal element , correspondingly @xmath318 and @xmath319 , connected by the symmetry transformation ( [ eqn : ocasym ] ) .
therefore , the total conductivity @xmath314@xmath6@xmath320 behaves as an isotropic object in the plane @xmath11-@xmath139 .
conversely , the tensors @xmath321@xmath12@xmath322 are diagonal in the basis of orthorhombic axes @xmath323@xmath12@xmath324 $ ] and @xmath325@xmath12@xmath38 $ ] , which are rotated with respect to cubic ones by 45@xmath37 . in the orthorhombic frame , they have only one nonvanishing diagonal element @xmath326@xmath12@xmath327@xmath12@xmath328 in the direction of propagation of the zigzag chain ( the @xmath325-direction ) .
this gives rise to an anisotropy of the optical conductivity , which has been observed experimentally in la@xmath14sr@xmath15mno@xmath16 by using a birefringence technique.@xcite the energy range corresponding to the bonding - nonbonding transitions roughly agrees with the position of the mid - infrared peak observed in la@xmath14sr@xmath15mno@xmath16 around 1.0 - 1.3 ev.@xcite high intensity of experimental peak may be partly attributed to the ( quasi- ) one - dimensional character of the problem and divergence of the optical conductivity at the band edges .
another possibility is the lack of the inversion symmetry at the corner sites @xmath29 and @xmath30 . in this case
, the atomic @xmath2 and @xmath3 orbitals may belong to the same representation of the local symmetry group .
this is an additional channel of mixing of the @xmath2 and @xmath3 states at the corner atoms , which contributes to probabilities of the optical transitions .
the jtd around the bridge sites can affect the conductivity spectrum indirectly , through the induced charge disproportionation , in a way similar to the intra - chain de interaction considered in sec .
[ subsec : jt.exchange ] .
since the charge disproportionation @xmath68@xmath69@xmath70 increases the energy gap between the bonding and nonbonding bands and decrease the width of the former , we expect the upward shift of the optical absorption center and narrowing of the spectrum in the region of the bonding - nonbonding transitions .
if the charge disproportionation does not take place ( @xmath68@xmath12@xmath70 ) , the optical conductivity is expected to be the smooth function in the region of bonding - antibonding transitions and reveals the same symmetry properties as for the bonding - nonbonding ones .
the resonant x - ray scattering near the mn @xmath4-absorption edge is considered as a powerful experimental tool , which allows to probe the charge and orbital distribution in the perovskite manganites.@xcite the interpretation of experimental data is , however , hampered by the fact that the direct dipole transitions are allowed to the @xmath3 states but not directly to the @xmath329 states in the case of @xmath4-absorption .
therefore , the understanding of how the @xmath3 states interact with polarized @xmath2 orbitals represents a special interest.@xcite here we would like to show how the geometry of the zigzag chain imposes some constraints on the distribution of the mn(@xmath3 ) states , which should be reflected in the lowest energy part of the @xmath4-absorption spectrum of manganites with the zigzag afm ordering . in accordance with the tb picture ( fig .
[ fig.tbdos ] ) , the first unoccupied band which is involved in the transitions is the nonbonding band composed of the @xmath2 orbitals of the corner atoms @xmath29 and @xmath30 .
if the hoppings between @xmath2 and @xmath3 orbitals are restricted by nearest neighbors , the @xmath3 states will have nonvanishing weight only at the bridge sites @xmath27 and @xmath28 in the nonbonding part of the spectrum .
this interaction , given by eqs .
( [ eqn : wf0ap ] ) and ( [ eqn : wfaabb ] ) , results in the ordering of @xmath330 and @xmath331 orbitals .
since the @xmath5 orbitals of the bridge atoms do not contribute to the nonbonding band , there is nothing to re - expand over the @xmath3 orbitals of the neighboring ( corner ) atoms , and the corresponding weight of the @xmath3 states at the corner atoms will be zero .
thus , in accordance with our tb picture , the lowest energy part of the @xmath4-absorption spectrum probes the @xmath330 and @xmath331 states of the bridge atoms , which carry the information about the distribution of the @xmath5 states at the corner atoms .
the purpose of this section is to discuss validity of the tb model for the zigzag afm state by comparing it with results of first - principles band structure calculations in the local - spin - density approximation ( lsda ) .
lsda and its extension in the form of the generalized gradient approximation ( gga ) work reasonably well in manganites.@xcite there are several unresolved problems , such as the relative stability of the jahn - teller distorted insulating a - type afm state and the metallic fm state in lamno@xmath10 : the standard band calculations account well for various magnetic properties of lamno@xmath10 with the experimental crystal structure,@xcite however the full optimization of the crystal structure substantially reduces the jtd and makes the a - type afm state energetically less favorable than the fm state.@xcite to say the truth , similar problem was encountered also in la@xmath14sr@xmath15mno@xmath16 , where after the structure optimization in gga the fm state had lower energy than the zigzag afm state.@xcite however , it is also true that at present the problem has no feasible solution .
for example , the lda@xmath6@xmath332 ( or gga@xmath6@xmath332 ) approach only worsen the picture of magnetic interactions in lamno@xmath10.@xcite this may be related with the fact that the relative position of the oxygen @xmath242 and mn(@xmath329 ) states ( the so - called charge - transfer energy ) is incorrect in lda@xmath6@xmath332 , that leads to a large error in the calculated parameters of magnetic interactions.@xcite thus , we believe that the lsda provides the most reliable reference point for the analysis of magnetic properties of manganites .
the quasi - one - dimensional tb model is a substantial simplification for realistic material , in several respect .
( i ) the de limit is not realized in perovskite manganites.@xcite
so , in the zigzag afm state the chains are not fully isolated from each other , and the system is not strictly one - dimensional .
( ii ) the distribution of mn(@xmath2 ) states is affected by other factors , which are not included explicitely in the tb model , particularly by the oxygen @xmath242 and mn(@xmath333 ) states.@xcite ( iii ) the mn(@xmath3 ) states generally form a very broad band . in this respect ,
our attempt to simulate the optical properties by starting with atomic @xmath3-levels and considering their interations with the @xmath5 bands in a perturbative manner was a crude approximation .
it allows to catch the basic symmetry properties of the optical conductivity tensor , but certainly not all the details and the absolute values of the conductivity itself .
we use the asa - lmto method in the nearly orthogonal representation.@xcite the wigner - seitz sphere radii for nonequivalent sites were chosen from the charge neutrality condition inside the spheres .
the calculations have been performed for the phenomenological virtual - crystal alloy y@xmath14sr@xmath15mno@xmath16 using the lattice parameters of the real two - dimensional perovskite la@xmath14sr@xmath15mno@xmath16.@xcite in addition , we also investigated the effect of the jtd around the bridge sites .
the latter is characterized by the parameter @xmath250 introduced in sec .
[ subsec : jt.exchange ] .
the partial densities of mn(@xmath2 ) and mn(@xmath3 ) states are shown in fig . [ fig.lsdados ] .
they reveal many similarities to the tb picture .
there are aslo some differences .
we note the following .
first , there is the clear splitting of the majority - spin @xmath2 states into the bonding band located around @xmath32@xmath13 ev ( the case of @xmath250@xmath12@xmath70 ) , the nonbonding bands around @xmath310 ev , and the antibonding band around @xmath334 ev .
two nonbonding bands are composed of the @xmath5 states of the corner ( @xmath29 and @xmath30 ) atoms and the @xmath154@xmath32@xmath153 ( @xmath152@xmath32@xmath153 ) states of the bridge @xmath27 ( @xmath28 ) atoms . even without the jtd , the system is insulating and the band gap is 0.3 ev .
this value is however smaller than the estimate @xmath310 ev expected from the tight - bonding analysis ( the value of effective two - center @xmath49 integral ) .
the difference is caused by the additional broadening of the bonding and nonbonding bands in the lsda .
the jtd increases the band - gap ( for example , for @xmath250@xmath12@xmath335 the band - gap is @xmath310 ev ) .
second , the partial densities of states in the bonding part of the spectrum clearly shows the characteristic peaks at the band edges , which is the signature of ( quasi- ) one - dimensional behavior .
the bandwidth is however larger than @xmath336@xmath32@xmath337@xmath1@xmath310@xmath133@xmath13 ev , expected from the tb analysis .
the density of nonbonding and antibonding state is modified more significantly .
particularly , the nonbonding and antibonding parts of the spectrum overlap with the minority - spin @xmath26 band ( not shown in fig .
[ fig.lsdados ] ) .
the minority - spin @xmath26 states may interact with the majority - spin @xmath5 states of the neighboring zigzag chains either directly , via next nearest - neighbor hoppings ( note , that the nearest - neighbor hoppings between the @xmath26 and @xmath5 orbitals are forbidden in the cubic lattice ref . ) , or indirectly , via the oxygen @xmath242 band . as the result , the nonbonding
states associated with the corner atoms @xmath29 and @xmath30 are significantly broadened ( to be compared with the @xmath250-peak expected from the tb analysis - fig .
[ fig.tbdos ] ) .
conversely , the @xmath154@xmath32@xmath153 and @xmath152@xmath32@xmath153 states of the bridge sites @xmath27 and @xmath28 are only weakly bonded , resulting in the high peak of the density of states around @xmath13 ev . due to the hybridization , the distribution of the majority - spin mn(@xmath3 ) states around the fermi level repeat the characteristic bonding - nonbonding - antibonding splitting of the mn(@xmath2 ) states . the nonbonding part of the spectrum is composed mainly of the @xmath11 ( @xmath139 ) orbitals of the bridge atoms @xmath27 ( @xmath28 ) .
the contribution of the @xmath3 orbitals of the corner atoms into this region is significantly smaller .
the corresponding optical conductivity is shown in fig .
[ fig.opt.lsda ] .
some details of calculations can be found in refs . .
here we only would like to mention that in order to speed up rather heavy calculations ( note that taking into consideration the zigzag afm ordering , the unit cell of y@xmath14sr@xmath15mno@xmath16 consists of 56 atoms ) , the brillouin zone integration in the calculations of optical conductivity was replaced by a summation with the phenomenological lorentzian broadening of @xmath338 ev .
this causes some artificial broadening of the spectrum . nevertheless , we believe that all important features are preserved in it , and were not washed out by the broadening . as the test , one can consider the off - diagonal element @xmath339 in the low - energy part of the spectrum .
it clearly shows two peak around @xmath340 ev and @xmath341 ev ( the case of @xmath250@xmath12@xmath70 ) , corresponding to two peaks of the ( quasi- ) one - dimensional density of states in the bonding region ( fig .
[ fig.lsdados ] ) , in a close analogy with the tb picture ( fig .
[ fig.opt.tb ] ) .
surprisingly however that the shape of diagonal conductivity in the @xmath342-plane is very different , contrary to our expectations based on the tb model . in the low - energy part of the spectrum it has only one large peak at @xmath310 ev . the difference can not be simply attributed to the broadening effects , because otherwise similar broadening would be expected also for the off - diagonal component of the conductivity tensor .
unfortunately , on the level of first - principles band structure calculations , it is rather difficult to decompose the optical conductivity unambiguously into partial contributions and to elucidate the origin of the spectral shape .
most probably , the difference between the lsda calculations and the tb analysis is caused at once by several factors outlined in the beginning of this section . in the tb model , two contributions to the conductivity spectrum in the region of bonding - nonbonding transitions , @xmath318 and @xmath343 , are comparable ( see fig .
[ fig.opt.tb ] ) . the off - diagonal element of the conductivity tensor , which is responsible for the anisotropy of optical properties , is related with the diagonal one by eq .
( [ eqn : ocbsym.1 ] ) .
therefore , @xmath344 is expected to be of the same order of magnitude as the total diagonal conductivity @xmath318@xmath6@xmath343 . however , in a more realistic situation , when the system is not strictly one - dimensional , the optical anisotropy is significantly reduced .
for example , in the lsda we have only @xmath345@xmath346@xmath347 in the region of bonding - nonbonding transitions .
the jtd around the bridge sites results in the upward shift of the low - energy peak and the simultaneous decrease of its intensity .
two experimental groups reported somewhat different results for the peak position at the low temperature : @xmath348 ev ( ref . ) and @xmath349 ev ( ref . ) .
both are larger than @xmath310 ev obtained in the lsda calculations without the jtd .
the jtd @xmath250@xmath12@xmath335 yields the new peak position @xmath348 ev , in agreement with one of the experimental reports .
however , the obtained intensity @xmath350 @xmath351 at the peak maximum appears to be smaller than the experimental one , which is about @xmath352 @xmath351.@xcite another effect of the jtd is the redistribution of the in - plane conductivity around @xmath353 ev , in the region of bonding - antibonding transition .
as expected for the layered perovskite compound , the in - plane ( @xmath354 ) and out - of - plane ( @xmath355 ) components of the optical conductivity reveal a strong anisotropy , in a good agreement with the experimental finding for la@xmath14sr@xmath15mno@xmath16.@xcite finally , we calculate nearest - neighbor magnetic interactions in y@xmath14sr@xmath15mno@xmath16 as the function of the jahn - teller distortion @xmath250 , using the same approach as in ref . . for small @xmath250
we obtain @xmath356@xmath133@xmath357@xmath6@xmath358 mev and @xmath359@xmath133@xmath360@xmath32@xmath361 mev .
therefore , even without the jtd , the magnetic interactions in the zigzag afm state show a very strong anisotropy @xmath362@xmath69@xmath363 , in a good agreement with the tb analysis . in the lsda ,
a small jtd @xmath250@xmath364@xmath256 becomes indispensable to stabilize the afm coupling @xmath359@xmath176@xmath70 between neighboring zigzag chains .
properties of the so - called charge - ordered manganites are typically regarded as one of the most striking examples of the strong coupling amongst the spin , charge and orbital degrees of freedom .
the coupling , which is reflected in the number of transport , structural and magnetic phenomena , is also believed to be responsible for the peculiar form of the ordered state realized at low temperatures . in the present work we tried to elucidate the cause of such an unusual behavior and to understand it from the viewpoint of the magnetic spin ordering .
we found that the zigzag form of the antiferromagnetic spin ordering , combined with the de physics , already provides a very consistent description for various low - temperature properties of the charge - ordered manganites . in the de limit ,
the one - dimensional fm zigzag chains become effectively separated from each other .
the one - dimensional character of the chains leads to the anisotropy of electronic properties .
the anisotropy of nearest - neighbor magnetic interactions in the de limit , combined with the isotropic superexchange interaction @xmath120 , readily explains the local stability of the zigzag afm state .
formally , the basic de picture is sufficient to understand the local stability .
the jtd significantly reduces the fm de contribution to the afm bonds , and in this way widens the region of local stability of the zigzag afm ordering .
it appears that in the wide range of parameters @xmath120 , the zigzag afm ordering is stable not only locally , but also globally , meaning that this is indeed the magnetic ground state of the system .
we also expect the anisotropy of optical properties , which is related with the distribution of the @xmath5 states at the corner atoms of the zigzag chain .
the two - fold degeneracy of the @xmath5 levels plays a very important role in the problem , and is responsible for the insulating behavior and the orbital ordering developed at the bridge sites of the zigzag chain .
thus , we believe that the nature of the low - temperature ce state in manganites is magnetic .
the charge ordering reduces mobility of the @xmath5 electrons and tends to destroy the ferromagnetic coupling within the chain .
therefore , it is expected to be small and play only minor role in the problem .
applicability of this picture to the high - temperature regime is still in question .
particularly , many charge ordered manganites are characterized by the existence of two transition temperatures : the long - range afm ordering occurs below the nel temperature @xmath365 , whereas the charge and orbital ordering orderings occur simultaneously below another critical temperature @xmath366 . in accordance with neutron scattering measurements , it holds @xmath365@xmath176@xmath366 ( see , e.g. , ref . ) .
this fact is typically considered as the strong experimental evidence that the charge and orbital degrees of freedom play a decisive role in the interval @xmath365@xmath176@xmath367@xmath176@xmath366 and drive the afm ce ordering at @xmath365.@xcite however , other experimental data suggest that the exact nature of the state realized between @xmath365 and @xmath366 is much more complicated , and still far from the complete understanding .
+ 1 ) some magnetic experiments simply do no see the existence of the transition point @xmath365 .
for example , the behavior of spin magnetization in the external magnetic field shows the characteristic metamagnetic transition both below and above @xmath365 , which disappears only at @xmath366.@xcite the magnetic susceptibility shows a pronounced peak at @xmath366 and no anomaly at @xmath365.@xcite these data suggest that , although there is no long - range magnetic order , the magnetic fluctuations and the effects of short - range order continue to play a very important role in the interval @xmath365@xmath176@xmath367@xmath176@xmath366 .
+ 2 ) the high - resolution electron microscopy clearly reveals the existence of the one - dimensional chains ( stripes ) even above @xmath365 , though the exact from of the stripes is not quite clear yet.@xcite it is also not clear whether these stripes have a magnetic origin or not .
if they do , it would be a strong argument in the favor of the magnetic scenario considered in the present work , although the perfect geometry of the fm zigzag chain may be destroyed at elevated temperatures . in this respect ,
an interesting theoretical result has been obtained by hotta _
et al_. they argued that the class of one - dimensional zigzag objects , which preserves the insulating behavior at @xmath11@xmath12@xmath13 is actually much wider and is not limited by the zigzag chain shown in fig .
[ fig.chains ] .
all these new zigzag configuration have higher energies , and therefore are not realized as the ground state at low temperatures .
however , they may carry a considerable weight in the thermodynamics averages and therefore contribute to the high - temperature behavior of the charge ordered manganites .
i thank k. terakura for valuable discussions .
the present work is partly supported by new energy and industrial technology development organization ( nedo ) .
the local density of states at the site @xmath88 is given by @xmath368 using the explicit expressions for the matrix elements of the green function , eqs .
( [ eqn : g11aa])-([eqn : g22bb ] ) , noting that @xmath32@xmath369@xmath32@xmath370@xmath6@xmath79^{-1}$]@xmath12@xmath371@xmath32@xmath372 , and taking into account that @xmath373 where the derivative is evaluated at the point @xmath71@xmath12@xmath374 , one can find the following expressions for the partial densities of states : @xmath375[\varepsilon(\varepsilon-\delta_{\rm c})-1 ] } } , \label{eqn : n11a}\ ] ] @xmath376 @xmath377 the total density of states , @xmath378@xmath12@xmath379@xmath6@xmath380@xmath6@xmath381 , is given by @xmath382[\varepsilon(\varepsilon-\delta_{\rm c})-1 ] } } + \delta(\varepsilon-\delta_{\rm c } ) .
\label{eqn : ntotal}\ ] ]
here we argue that the invariance of the total energy with respect to uniform rotations of all spin magnetic moments by the same angle automatically leads to the isotropic heisenberg form for the total energy change associated with small rotations of an arbitrary type eq .
( [ eqn : heisenberg ] ) . for simplicity
we consider the fm ordering for which @xmath106@xmath198@xmath383 does not depend on the site @xmath107 . by expanding @xmath384 $ ] in the taylor series
we obtain in the second order : @xmath385 \simeq e_t [ { \bf e}^0 ] - \sum_{\it i } f_{\it i } ( \mbox{\boldmath$\delta$}^{(2)}{\bf e}_{\it i } \cdot { \bf e}^0 ) -\frac{1}{2 } \sum_{\it ij } j_{\it ij } ( \mbox{\boldmath$\delta$}^{(1)}{\bf e}_{\it i } \cdot \mbox{\boldmath$\delta$}^{(1)}{\bf e}_{\it j } ) .
\label{eqn : ap1}\ ] ] in eq .
( [ eqn : ap1 ] ) we employed the requirement of rotational invariance for the perturbed system : if all spins are rotated the same angle , the total energy does not change .
therefore , @xmath383 and @xmath109 may enter the expression for the total energy change only through the scalar products .
noting that @xmath386 and @xmath387 are given by eq .
( [ eqn : rotations ] ) and employing again the requirement of rotational invariance for the unperturbed system ( that is the total energy does not change if all spins @xmath125 are rotated by the same angle @xmath388@xmath198@xmath389 ) we find the following condition : @xmath390 this proves validity of eq .
( [ eqn : heisenberg ] ) for the fm ordering .
the generalization to the afm ordering is straightforward , because similar arguments can be applied both for the intra- and inter - spin - sublattice interactions in the afm state . here we consider only the hard condition of the local stability of the a - type afm ordering and require the sign of the nearest - neighbor magnetic coupling to correspond directly the type of the magnetic ordering .
for example , due to existance of the longer - range interactions between the antiferromagnetically coupled layers , the stability of the a - type afm ordering with respect to the spin canting is given by a
condition , where the lower boundary for @xmath224 is only @xmath394 when @xmath11@xmath12@xmath13.@xcite the canted spin states of the fa type have been considered in our previous work ( ref . ) .
the canted spin states of the ag type can be generated along the same line and corresponds to the combination of angles @xmath395 , in the notations of ref . .
if stable , the ag states have the lowest energy amongst the collinear fm , a- , c- , and g - type afm states and all possible intermediate canted states for @xmath11@xmath12@xmath13 . i. v. solovyev and k. terakura , j. korean phys . soc .
* 33 * , 375 ( 1998 ) ; and in proceedings of moscow international symposium on magnetism ( moscow state university - faculty of physics , moscow , 1999 ) , p. 155 . for comparison
, the cooperative jtd in lamno@xmath10 corresponds to @xmath250@xmath133@xmath230
g. matsumoto , j. phys .
* 29 * , 606 ( 1970 ) ; j. b. a. a. elemans , b. van laar , k. r. van der veen , and b. o. loopstra , j. solid state chem . * 3 * , 238 ( 1971 ) .
we do not consider the on - site interactions between the @xmath2 and @xmath3 orbitals , which are caused by the nonsphericity of the coulomb potential .
the effect is believed to be small.@xcite in this respect , results of the lsda band structure calculations presented in sec .
[ sec : lsda ] correspond to the same level of approximation : the calculations were performed in the asa geometry,@xcite meaning that at each atomic site the coulomb and exchange potentials were averaged over the angles within the atomic sphere .
n. hamada , h. sawada , and k. terakura , in _ spectroscopy of mott insulators and correlated metals _ , edited by a. fujimori and y. tokura ( springer - verlag , berlin , 1995 ) , p. 95 ; d. d. sarma , n. shanthi , s. r. barman , n. hamada , h. sawada and , k. terakura , phys .
lett . * 75 * , 1126 ( 1995 ) ; w. e. pickett and d. j. singh , phys .
b * 53 * , 1146 ( 1996 ) .
moreover , in accordance with resonant x - ray scattering studies , the charge ordering is characterized by much larger correlation length and is considered as the driving force of the orbital ordering
m. v. zimmermann , j. p. hill , d. gibbs , m. blume , d. casa , b. keimer , y. murakami , y. tomioka , and y. tokura , phys .
* 83 * , 4872 ( 1999 ) .
though , this is not the only one scenario .
another possibility is the temperature transition of the ce - type afm state to the homogeneous fm state , which is observed for example in pr@xmath396sr@xmath396mno@xmath10 and nd@xmath396sr@xmath396mno@xmath10.@xcite this schenario seems to be consistent with the magnetic origine of the ce state . | the low - temperature properties of the so - called charge ordered state in 50% doped perovskite manganites are described from the viewpoint of the magnetic spin ordering . in these systems ,
the zigzag antiferromagnetic ordering , combined with the double - exchange physics , effectively divides the whole sample into the one - dimensional ferromagnetic zigzag chains and results in the anisotropy of electronic properties .
the electronic structure of one such chain is described by an effective @xmath0@xmath1@xmath0 hamiltonian in the basis of mn(@xmath2 ) orbitals .
we treat this problem analytically and consider the following properties : ( i ) the nearest - neighbor magnetic interactions ; ( ii ) the distribution of the mn(@xmath2 ) and mn(@xmath3 ) states near the fermi level , and their contribution to the optical conductivity and the resonant x - ray scattering near the mn @xmath4-absorption edge .
we argue that the anisotropy of magnetic interactions in the double - exchange limit , combined with the isotropic superexchange interactions , readily explains both the local and the global stability of the zigzag antiferromagnetic state .
the two - fold degeneracy of @xmath5 levels plays a very important role in the problem and explains the insulating behavior of the zigzag chain , as well as the appearance of the orbital ordering in the double - exchange model .
importantly , however , the charge ordering itself is expected to play only a minor role and is incompatible with the ferromagnetic coupling within the chain .
we also discuss possible effects of the jahn - teller distortion and compare the tight - binding picture with results of band structure calculations in the local - spin - density approximation . |
left - handed materials , plasmon - polariton systems , and localized modes in random media are attracting nowadays the ever - increasing interest of physicists and engineers .
this is due to both the fundamental character of the problems and promising applications in photonics , subwavelength optics , random lasing , etc .
there have been a number of separate investigations and reviews of these phenomena ( see , e.g. , @xcite ) , but no detailed comparison has been attempted in spite of their deep underlying similarities . discussing analogies between these systems and with their simple classical counterparts provides a more unified understanding , new insights , and can be illuminating .
there are numerous examples of fundamental physical phenomena that can be explained in terms of classical oscillators .
resonators provide the next - step generalization revealing additional common features such as , e.g. , the `` critical coupling effect '' crucial for open wave systems with dissipation .
below we briefly describe the complex systems mentioned above and analyze them in terms of simple resonator models .
note that here we do not consider microwave and optical resonators , quantum dots , mie resonances , impurity zones in periodic structures , cavities in photonic srystals , etc .
our goal is to demonstrate that a broad variety of physical phenomena in systems that do _ not _ contain conventional resonant cavities , nonetheless can be adequately described in terms of classical resonators . in 1968
veselago examined electromagnetic wave propagation in a virtual medium with simultaneous negative permittivity and permeability @xcite .
he showed that such left - handed medium ( lhm ) was characterized by an unusual negative refraction : the incident and refracted beams at the interface between the lhm and ordinary media ( hereafter , the vacuum ) lie on the same side of the normal to the interface .
this property implies that a flat lhm slab can act as a lens forming a 3d image of the object , as illustrated in fig . 1 .
interest in lhm grew very fast after pendry s paper @xcite , where it was shown that a lhm slab can act as a _ perfect _ lens .
namely , a lhm slab with permittivity and permeability having the same absolute value as in the surrounding medium @xmath0 forms a perfect copy of an object : all details of the object , even smaller than the wavelength of light , are reproduced ( for reviews , see , e.g. , @xcite ) . in practice ,
left - handed materials are artificial periodic structures ( metamaterials ) , and any `` perfect lens '' will have a finite resolution limited by the size of the unit cell .
metallic thin films can also provide super - resolution for the near evanescent field @xcite .
but for propagating waves , a metallic layer acts as a very good mirror : only an exponentially small part of the radiation can penetrate through it .
surprisingly , in 1998 ebbesen _
_ @xcite found that an optically opaque metal film perforated with a periodic array of _ sub - wavelength_-sized holes was abnormally _ transparent _ for certain resonant frequencies or angles of incidence , fig
. 2 . the energy flux through the film can be orders of magnitude larger than the cumulative flux through the holes when considered as isolated ( for reviews , see , e.g. , @xcite ) .
in addition to its fundamental interest , this effect offers promising applications as tunable filters , spatial and spectral multiplexors , etc .
( see , e.g. , @xcite ) .
total internal reflection ( tir ) occurs when an oblique light beam strikes an interface between two transparent media , and the refractive index is smaller on the other side of the interface .
for instance , the incident light is totally reflected from the prism bottom ( which is the tir surface ) , as shown in fig .
a polished silver plate is also a very good mirror that reflects all the incident light , as in fig .
however , when the tir surface and the plate are located right next to each other , the reflected beam can disappear and all the light can be _ totally absorbed _ by the silver plate @xcite , as illustrated in fig . 3c
. total absorption can also be observed in the microwave frequency band . when replacing the prism by a reflecting sub - wavelength diffraction grating , fig .
3d , and the silver plate by an overdense plasma ( i.e. , a plasma whose langmuir ( plasma ) frequency is higher than the incident wave frequency ) , fig . 3e
, the same effect appears : the incident electromagnetic wave can be totally absorbed by the plasma @xcite , fig . 3f , even though both elements act separately as very good mirrors .
extraordinary optical transmission and total absorbtion can be observed in a quite different system : 1d random dielectric media .
although the medium is locally transparent , the wave field intensity typically decays exponentially deep into the medium , so that a long enough sample reflects the incident wave as a good mirror .
this is because of multiple wave scattering in randomly - inhomogeneous media producing a strong ( anderson ) localization of the wave field @xcite ( for reviews , see , e.g. , @xcite ) .
a simple manifestation of this effect is the almost - total reflection of light from a thick stack of transparencies @xcite .
however , there is a set of resonant frequencies , individual for each random sample , which correspond to a _
high transmission _ of the wave through the sample accompanied by a large concentration of energy in a finite region inside the sample @xcite ( see fig . 4 ) . like optical `` speckle patterns '' ,
such resonances ( localized states ) represent a unique `` fingerprint '' of each random sample . in active random media , regions that localize waves
are sources of electromagnetic radiation producing a so - called random lasing effect , which offers the smallest lasers , just a few - wavelengths in size @xcite .
if the sample has small losses , the resonant transparency can turn into a _ total absorption _ of the incident wave @xcite .
the notion of resonator implies the existence of eigenmodes _ localized _ in space .
the localization of modes is usually achieved by a sandwich - type `` mirror - cavity - mirror '' structure which is analogous to a quantum - mechanical potential well bounded by potential barriers and can be of any nature ( see fig . 5 ) . in a closed resonator without dissipation
each mode is characterized by its resonant frequency ( energy level ) @xmath1 and spatial structure of the field @xmath2 .
the eigenmode field @xmath3 can be factorized as @xmath4 where @xmath5 is a solution of the harmonic oscillator equation : @xmath6 depending on whether the modes are localized in all spatial dimensions or not , the resulting spectrum can be either discrete or continuous .
the resonator can be non - conservative due to internal _ dissipation _ of energy .
furthermore , the barriers can allow small energy _
leakage _ either from or to the cavity , e.g. due to ` under - barrier ' tunnelling via evanescent waves . in such cases
one has to consider the resonator as an open system with quasi - modes characterized by fuzzy energy levels of a finite width , fig .
the time dependence of the fields is not purely harmonic anymore and can be described as an oscillator with damping : @xmath7 here , the dimensionless _ q - factor _ characterizes the total losses in the resonator : @xmath8 where @xmath9 and @xmath10 are the q - factors responsible for the dissipation and leakage , respectively .
the dimensionless half - width of the resonant peak in the spectrum equals @xmath11 the tunnelling of an incident plane wave through an open 1d resonator is characterized by the transmission and reflection coefficients @xmath12 and @xmath13 .
the transmittance @xmath12 is usually small due to the opaque barriers , but if the frequency of the incident wave coincides with one of the eigenmode frequencies , an effective resonant tunneling occurs . the corresponding transmission coefficient , @xmath14 , is given by @xcite : @xmath15 here @xmath16 and @xmath17 are the leakage q - factors ( @xmath18 ) , which are related to the transmittances @xmath19 and @xmath20 of the two barriers by @xcite @xmath21 here @xmath22 is the wave group velocity inside the resonator and @xmath23 is the resonator cavity length ( so that @xmath24 is the round - trip travel time of the wave inside the cavity ) .
hereafter we will assume @xmath25 , where @xmath26 is the wave number of the resonant wave .
note that the total transparency , @xmath27 , is achieved only in a dissipationless symmetric resonator , i.e. @xmath28 the reflection coefficient @xmath13 is close to unity off - resonance and is characterized by sharp resonant dips on - resonance .
the resonant reflection coefficient is given by @xcite : @xmath29 in contrast to the transmittance ( [ eq3 ] ) , the reflectance ( [ eq6 ] ) reaches its minimum value also in dissipative asymmetric resonators @xcite : @xmath30 this is the so - called _ critical coupling _ effect . in the important particular case when the second barrier is opaque , @xmath31 , @xmath32 , so that the total transmittance vanishes , @xmath33 , the reflectance spectrum exhibits pronounced resonant dips , with @xmath34 , if the leakage and dissipation q - factors are equal to each other ( see , e.g. @xcite ) : @xmath35
. then , the incident wave is totally absorbed by an open resonator , so that all the wave energy penetrates into the resonator and dissipates therein .
two resonators can be coupled by the fields penetrating through the barriers .
this system ( outside the critical coupling regime ) can be effectively described by the coupled oscillators model .
when the first ( incoming ) resonator is excited by a monochromatic source with frequency @xmath36 , the appropriate oscillator equations can be written as follows : @xmath37 where @xmath38 @xmath39 is the field in the first ( second ) resonator , @xmath40 and @xmath41 are the dimensionless time and frequency , @xmath42 is the coupling coefficient , and @xmath43 is the effective exciting force from the incident field .
the steady - state solutions of eqs .
( [ eq8 ] ) are oscillations with amplitudes @xmath44 and @xmath45 given by : @xmath46 near - resonance , @xmath47 , the frequency dependencies of these amplitudes at different values of the @xmath48 factor are shown in fig .
there can be seen that when the condition @xmath49 is satisfied , there are two collective resonant modes with equal field amplitudes in the two resonators .
their frequencies are shifted from the eigenfrequency of the oscillators , @xmath50 , due to losses and coupling : @xmath51 as @xmath48 decreases , the resonant peaks in the spectra are located near each other and meet when @xmath52 . in the regime
@xmath53 there is one peak at @xmath54 .
the parameter @xmath48 that appears in the model has a simple physical meaning : it determines whether the two resonators should be considered as essentially coupled or isolated .
when @xmath55 , the losses are negligible and the field characteristics are essentially determined by the coupling . remarkably , in this case the field intensity in the first ( incoming ) resonator is negligible at @xmath54 , and almost all the energy is concentrated in the second resonator : @xmath56 . on the contrary ,
when the losses prevail over the coupling , @xmath57 , the incident wave only excites the first resonator , and the energy is concentrated mostly in it : @xmath58 .
the interface between materials with different signs of the permittivity , @xmath59 and @xmath60 , ( or permeability , @xmath61 and @xmath62 ) , supports surface @xmath63- ( or @xmath64- ) polarized waves , also known as _ plasmon - polaritons _ ( pp ) .
pp were discovered in 1957 by ritche @xcite while studying a metal - vacuum interface . renewed
interest in plasmon - polaritons comes from their considerable role in contemporary nano - physics @xcite .
the interface between regular ( @xmath59 , @xmath61 ) and left - handed ( @xmath60 , @xmath62 ) materials supports pp with an arbitrary polarization @xcite .
pp are electromagnetic waves which are trapped at the interface , their electromagnetic fields decaying exponentially deep into both media ( fig .
hence , the interface forms a peculiar resonator with eigenmodes which are localized along the normal to the interface but can propagate freely along the interface .
spatial eigenfunctions of this resonator have the form : @xmath65 and are characterized by a dispersion relation @xmath66 . here
the interface is associated with the @xmath67 plane , the subscript `` @xmath68 '' indicates vectors within the @xmath69 plane , and the decay constant @xmath70 can take different values in the two media .
the plasmon - polariton resonator possesses all the features that are inherent to usual resonators : eigenfrequency , q - factor , topography of eigenmode fields , etc .
it will be shown below that the identification of pp as a resonator is more than an analogy , since it captures the main physical process underlying this phenomenon .
an exponential profile of the pp field suggests that it can interact with _ evanescent _ , non - propagating fields from an external source , which are characterized by a purely imaginary wave - vector component : @xmath71 .
furthermore , an incident _ propagating _ electromagnetic plane wave can not excite the pp resonator . this is because for propagating waves ( pw ) @xmath72 , whereas for plasmon - polaritons @xmath73 . at the same time ,
evanescent waves ( ew ) are characterized by @xmath74 and can excite the pp resonator .
there are methods to convert a propagating wave into an evanescent one .
this allows the interaction of light with plasmon - polaritons , which has lead to a new branch of physics : _ plasmonics _ ( see , e.g. , @xcite ) .
let us examine the transmission of a plane wave through an optically thick metal film perforated with small , sub - wavelength holes , as shown in fig .
two surfaces of the smooth metal film can be associated with two identical pp resonators , coupled by their fields , as shown in fig .
as it has been noticed , pps can not be directly excited by the incident plane wave ; however , pps can interact through periodic modulations of the surface @xcite .
the effective interaction of pps with light occurs at some resonance frequency @xmath75 ( or angle of propagation @xmath76 ) , at which their wave vectors differ by a reciprocal lattice vector @xmath77 : @xmath78 one can say that the pp wave vector shifted by a reciprocal lattice vector acquires a real @xmath79-component , or vice versa , the shifted propagating mode becomes evanescent in the @xmath79 direction .
thus , the periodic structure can be considered as a _ mode transformer_. ( it is worth remarking that while in microwave electronics such structures are used for slowing down the eigenmodes , here we deal with a speedup of the pp eigenmodes . )
the periodic corrugation of the metal surface can be treated as a diffraction grating placed on the surface .
the grating can be located at a distance @xmath80 from the smooth surface ; it remains coupled with plasmons - polaritons by their field @xcite , as shown in fig .
7b , c .
now we can make use of the general theory of resonators .
assuming the dissipation to be negligible , @xmath81 , the q - factor of the pp resonator is determined by the energy leakage from the resonator due to the transformation of the evanescent waves into the propagating ones : @xmath82 here , @xmath83 is the transformation coefficient at the diffraction grating , and the exponential dependence arises due to decay of the evanescent field intensity between the metal surface and grating .
the coupling coefficient between the two pp resonators is determined by the field of the first resonator acting on the second one : @xmath84 where @xmath85 is the film thickness .
the dependence of the transmission coefficient @xmath12 on the normalized incident wave frequency @xmath86 is described by eqs .
( [ eq8])([eq10 ] ) , and is illustrated in fig .
it exhibits two nearby peaks : @xmath27 at @xmath87 , when @xmath88 , or one peak @xmath89 at @xmath54 when @xmath90 . a characteristic field distribution for the total transmission is shown in fig .
the coupling parameter decreases as @xmath85 grows , and the transmission spectrum @xmath91 changes as in fig .
6a . the same dependence of the transmission spectrum on the film thickness has been obtained in @xcite and in many other papers concerned with particular geometries and specific modifications .
in fact , all these features are just general properties of two coupled resonators , independently of details .
thus , the light transmission through a perforated ( corrugated ) metal film can be divided into three processes : ( i ) transformation of the incident plane wave into an evanescent wave on the first diffraction grating , ( ii ) resonant `` penetration '' of the evanescent field through two coupled plasmon - polariton resonators , ( iii ) reverse transformation into the propagating wave on the second grating , fig .
it may seem at first that the larger the transformation coefficient at the diffraction grating is , the better the transmission is .
however , larger transformation coefficients result in smaller q - factors .
when @xmath92 exceeds a critical value , the transmission becomes less than one and decreases with @xmath92 @xcite . in the above model
, it is easy to incorporate dissipation characterized by a small imaginary part of the dielectric constant , @xmath93 , by introducing the dissipation q - factor @xmath94 the dissipation is negligible only if @xmath95 .
otherwise , even very small dissipation will drastically affect the resonance phenomena as it is compared to the exponentially small parameters ( [ eq12 ] ) and ( [ eq13 ] ) .
if @xmath96 , the dissipation may substantially suppress the transmission .
when @xmath97 , the dissipation breaks down the coupling between two pp resonators on either side of the film , and they can be regarded as essentially independent . for the system under consideration
this means that only the first resonator will be excited by the incident wave and the metallic film can be considered as a semi - infinite medium , fig .
7c . in such a case ,
the transmission through the film vanishes at all frequencies . at the same time , the resonances show up in the reflection spectrum which exhibits sharp dips at some frequencies . for some critical distance between the diffraction grating and metal , @xmath98 ,
the resonant reflectance drops to zero , @xmath34 , and the incident wave is totally absorbed by the metal , fig .
3 . this effect can be readily explained in terms of the same resonator model : ( i ) the incident plane wave transforms into an evanescent mode at the diffraction grating and ( ii ) it excites a pp resonator at the metal surface and is totally absorbed due to the critical coupling effect , fig .
7c . in our case
the critical coupling condition , eq .
( [ eq7 ] ) , reads @xmath99 with eqs .
( [ eq12 ] ) and ( [ eq14 ] ) . the application of diffraction gratings for the pp resonator excitation is most convenient in plasma experiments .
when a properly designed grating is placed in front of the plasma surface , the reflected wave vanishes ( see fig . 3 bottom ) @xcite . an analogous phenomenon in optics
is known as `` frustrated total internal reflection '' @xcite . similarly to a diffraction grating , a total internal reflection interface can be used for plasmon - polariton excitation on a metal surface @xcite . in the so - called otto - configuration ,
a metal is placed at a distance @xmath80 from the bottom of a prism where the light is totally reflected ( top of fig .
3 ) . the incident light , with @xmath100 ,
penetrates into the prism with the wave vector projection @xmath101 ( @xmath102 is the refractive index of the prism ) .
it generates an evanescent wave in vacuum near the bottom and can excite the the pp resonator at a resonance frequency @xmath75 ( or angle of propagation @xmath76 ) where @xmath103 the leakage q - factor of the pp resonator is given by eq .
( [ eq12 ] ) , where @xmath104 is the coefficient of transformation to the evanescent wave at the bottom of the prism . at a critical distance @xmath98 the reflected light disappears , which evidences the critical coupling regime .
note that when the metal film is so thin that @xmath105 , the high resonant transparency of the film can be observed when the identical prism is located symmetrically near the opposite side of the film @xcite .
this configuration is absolutely analogous to the above - considered grating metal grating system , fig .
7b . the total absorption of an incident wave due to the critical coupling can be used for the simultaneous determination of both the real and imaginary parts of the metal ( plasma ) permittivity .
on the one hand , the resonant frequency @xmath1 ( or the angle of incidence ) is determined by the resonance with the pp mode , which depends on the real part of the metal permittivity , @xmath106 . on the other hand ,
the critical coupling distance @xmath107 between the prism ( grating ) and the metal ( plasma ) surface depends on the dissipative q - factor ( [ eq14 ] ) related to the imaginary part @xmath108 of the permittivity .
thus , the critical coupling regime provides a mapping between @xmath109 and @xmath110 and makes it possible to retrieve the complex permittivity of the metal ( plasma ) via external measurements .
while a dielectric medium is transparent for propagating plane waves and a metal surface supports pp evanescent modes , a left - handed material combines both of these features .
let the source of a monochromatic electromagnetic field ( the object ) be located at a distance @xmath80 from the surface of a flat slab of an ` ideal ' lhm ( @xmath111 ) of width @xmath112 , as shown in fig .
the source radiates propagating plane - wave harmonics with @xmath113 , as well as evanescent waves with @xmath114 the propagating waves are focused by the lhm slab and form the image on the opposite side of the slab , fig . 1 .
the ideal lhm is perfectly matched with the vacuum due to the equivalence of their impedances @xmath115 , and , therefore , there is no reflected wave in this case .
the image field is almost equal to the source one : all the plane waves reach the focal plane ( located at a distance @xmath116 from the slab ) with the same phase as they had in the source plane .
the abberation ( imperfection ) of the image might only be caused by the loss of evanescent harmonics , which are responsible for the sub - wavelength details of the object .
remarkably , even sub - wavelength information is not lost in the ideal lhm ( pendry s ) lens .
this can be easily understood if we consider the surfaces of the lhm slab as two coupled pp resonators , as we did to explain the high transmission of the perforated metalic films .
evanescent waves from the source excite the first pp resonator .
a distinguishing feature of the pp mode at the ideal lhm / vacuum interface is that its dispersion relation is precisely the same as for evanescent modes in the vacuum @xcite .
this implies that _ all _ the evanescent waves ( [ eq16 ] ) are in resonance with the pp resonator on the ideal lhm surface @xcite .
in other words , @xmath117 and @xmath118 for any frequency ( the material dispersion is neglected here ) .
the evanescent field distribution can be found from eqs .
( [ eq8 ] ) and ( [ eq9 ] ) .
the pp resonators at the dissipationless lhm surface are characterized by an infinite q - factor , @xmath119 because there is no leakage from the pp to radiative modes .
we associate the amplitudes @xmath44 and @xmath45 with the field amplitude at the input and output surfaces of the slab . then the effective external force is given by @xmath120 where @xmath121 is the amplitude of the evanescent field of the source .
the coupling parameter is given by eq .
( [ eq13 ] ) , as it was for the metallic film .
according to eqs .
( [ eq9 ] ) with @xmath54 and @xmath122 ( see also fig .
6 ) , the input resonator is not excited , @xmath123 whereas the amplitude at the output is exponentially large : @xmath124~.\ ] ] in the image half - space , the evanescent field decreases with the same decrement @xmath70 and at the distance @xmath116 from the second interface ( the total distance from the source is @xmath125 ) takes on the initial value ( fig .
7d ) : @xmath126 since the phases of evanescent waves are not changed along the @xmath79-axis , the evanescent fields in the focal plane precisely reproduce those in the source plane .
this means that the image created by both propagating and evanescent waves is a _
perfect _ copy of the source .
exactly the same evanescent field distribution in the pendry s lens follows from the accurate solution of maxwell equations ( see , e.g. , @xcite ) .
it is worth noting that the electromagnetic nature of waves has not been involved in our consideration of sub - wavelength imaging .
the same result can be achieved using other kinds of waves , e.g. , liquid - surface waves @xcite , surface electromagnetic waves propagating along special types of interfaces @xcite , and surface josephson plasma waves @xcite in layered superconductors .
if a small dissipation is present in lhm , it can be taken into account by introducing the dissipation q - factor ( refeq14 ) in eqs .
( [ eq8 ] ) and ( [ eq9 ] ) ( here , for simplicity , the permeability is assumed to be real ) .
the destructive effect of dissipation in the lhm , reducing the image quality , is defined by the ratio between the q - factor and the coupling parameter @xmath127 . when @xmath128 , the image abberation is small . when @xmath129 , the dissipation is crucial and practically destroys the penetration of evanescent waves through the lhm slab .
this limitation of the ideality of pendry s lens has been discussed in @xcite using a wave approach . at the same time
, the dissipation affects the propagating waves in a lhm lens in the same manner as in normal media , because the lhm slab do not form resonator for propagating waves .
the dissipation significantly affects the propagation waves only when @xmath130 .
the resonant transmission of waves through a 1d random sample is accompanied by a large concentration of energy inside the sample , as shown in fig . 4 .
such field distributions can be regarded as quasi - modes of an open system . among various localized states ,
high transparency accompanies only those modes that are located near the center of the sample .
localized modes and anomalous transparency can be explained by the existence of effective high - q resonator cavities inside of the sample .
figure 8 demonstrates the transparencies of different parts of the sample from fig .
it is clearly seen that the middle section , where the energy was concentrated , is almost transparent to the resonant frequencies , while the side parts are practically opaque to the wave .
thus , each localized state at a frequency @xmath75 can be associated with a typical resonator structure comprised of an almost transparent segment ( `` cavity '' ) bounded by essentially non - transparent regions ( `` barriers '' ) @xcite .
the wave tunnelling through such a system can be treated as a particular case of the general problem of the transmission through an open resonator .
the distinguishing feature of the random medium is that there are no regular walls ( the medium is locally transparent in each point ) and transmittances of barriers are exponentially small as a result of anderson localization .
moreover , different segments of the sample turn out to be transparent for different frequencies , i.e. , each localized mode is associated with its own resonator . the resonant tunnelling through a random sample can be described by eq .
( [ eq3 ] ) , where the barrier transmittances and q - factors are estimated as @xcite @xmath131 and the total leakage q - factor is @xmath132 . here
@xmath133 and @xmath134 are the distances from the cavity to the ends of the sample ( the barrier lengths ) and @xmath135 is the localization length .
the latter is the only spatial scale responsible for the localization , and the cavity size should be estimated as @xmath136 .
this simple model drastically reduces the level of complexity of the problem : the disordered medium with a huge number of random elements can be effectively described now through a few characteristic scales , namely , the localization length , the wavelength , and the size of the sample . all the main features and characteristics of the resonances ( transmittance , field intensity , spectral half - width and the density of states ) can be estimated from the resonator model in good agreement with experimental data @xcite
. in particular the perfect resonant transmission takes place only for a symmetric dissipationless resonator , eq .
( [ eq5 ] ) , which corresponds to wave localization in the middle of the sample and a maximal total q - factor .
note that a long enough sample can contain two or more isolated transparent regions where the wave field is localized .
these form the so - called `` necklace states '' predicted in @xcite and observed in @xcite .
necklace states can be easily incorporated in our general scheme as two or more resonators coupled by their evanescent fields , eqs .
( [ eq8])([eq10 ] ) @xcite .
the coupling coefficient between the nearest resonators is @xmath137 where @xmath85 is the distance between the effective cavities .
it seems reasonable to assume that dissipation in the sample material worsens the observability of resonances .
however , surprisingly , small losses can improve the conditions for the detection of localized states
. a large number of resonances , which are not visible in the transmission spectrum , become easily detected in the _ reflection _ spectrum @xcite , fig . 9 .
this is clarified in terms of the critical coupling phenomenon . if the dissipation , @xmath138 , given by eq .
( [ eq14 ] ) , exceeds the leakage , @xmath139 , for the modes localized in the middle of the sample : @xmath140 the transmission is strongly suppressed for all frequencies , and @xmath141 . at the same time , the other states located closer to the input of the sample and , therefore , characterized by higher @xmath139 can be excited .
according to the critical coupling condition ( [ eq7 ] ) , the resonant reflectance drops to zero when the dissipation and leakage q - factors are of the same order .
for the modes localized in the first half of the sample we can set , with an exponential accuracy , @xmath142 , @xmath143 , so that the critical coupling condition reads @xmath35 as for the case of a semi - infinite medium .
the resonator model enables one to find characteristic parameters of localized states and of the sample via external measurements of the transmission and reflection coefficients @xcite . by measuring resonant and typical off - resonance values of the transmittance and reflectance , eqs .
( [ eq3 ] ) and ( [ eq6 ] ) , along with the resonance spectral half - width , it is possible to determine ( at least , to estimate ) the localization length , dissipation factor , position of the localized state , and its field intensity .
some of these internal quantities usually can not be determined via direct measurements , but are crucial , e.g. , for the random lasing problem .
for example , the critical coupling condition connects the position of the localization region with the dissipation rate in the medium , while the latter can be determined through the half - width of the resonant deep in the reflectance .
it should be also noted that random systems consisting of repeated elements of several types can exhibit transmission resonances of another kind , which are not accompanied by the energy localization and can not be described by the resonator model , see , e.g. , @xcite . * resonator characteristics * & * enhanced transparency * & * total absorption in plasma * & * frustrated tir in optics * & * ideal lhm lens * & * localization in random medium * + * dissipation q - factor , * @xmath138 & + * leakage q - factor , * @xmath139 & & @xmath144 & @xmath145 , @xmath146 + * coupling coefficient , * @xmath127 & @xmath147 & & @xmath147 & @xmath148 + * resonance condition , @xmath75 * & & @xmath149 & @xmath150 & @xmath75 +
the sub - wavelength resolution of a flat lhm lens , abnormal transparency of a perforated metal film , localized states in disordered media , frustrated total internal refraction , and total absorption of an electromagnetic wave by an overdense plasma are all phenomena related to different areas of physics and are characterized by different spatial scales , from the nano - scale to centimeters and larger . in spite of such enormous differences ,
the main properties of these phenomena have much in common with each other and , on a deeper level , with simple resonator systems .
as we have shown , all these phenomena can be treated in a universal way as wave transmission through one or two coupled resonators .
a careful mapping between the resonator and the problem parameters allows one to understand thoroughly the physical properties of the problem and forecast how the parameters affect the result .
of course , accurate descriptions of wave transmission through complex systems ( for example , periodically - perforated metal films or random media ) involve particular details of a given sample and depend , e.g. , on the geometry of the periodic structure or on the specific realization of the random process .
nonetheless , fundamental features of these systems which are independent of details can be revealed only through a unified approach emphasizing the physical essence of the problem .
resonator models provide such an approach . in some cases ( e.g. , for evanescent fields in the lhm lens ) resonator description results in
the _ exact _ solution of the problem .
furthermore , in the case of random media such model is the _ only _ formalism which enables one to estimate the parameters of the individual localized states .
one of the important common features of all resonator systems is their high sensitivity to internal dissipation .
even very small dissipation , which has negligible effects for usual propagating waves , may dramatically modify the localized resonance states .
usually dissipation destroys the resonant transmission but develops resonant dips in the reflection spectrum .
the reason for this is that the excitation of a resonator is always accompanied by a huge field intensity therein , proportional to the q - factor .
the energy dissipated per unit time is determined by the product of the dissipation rate and the field intensity .
thus , a small dissipation rate is multiplied by a high q - factor and can be crucial . also , establishing a one - to - one correspondence with classical resonator allows retrieving the _ internal _ characteristics of an investigated system using the _ external _ response to a probing signal ( incident wave ) . in this way
, one can determine the complex permittivity of metal or plasma , location and field intensity of localized states in random medium , etc .
remarkably , dissipation can be favorable for such purposes , revealing some hidden internal features through the critical coupling effect . to conclude ,
the central result of this brief review , i.e. the mapping between the resonator and the problems parameters , is summarized in table 1 .
we have considered only a few , probably more intriguing and non - trivial , systems allowing the resonator consideration .
a more complete list of such systems would be much longer , since any wave system with localized modes can be treated as a generalized resonator .
in particular , numerous quantum systems ( not considered here ) with potential wells , tunnelling , and relaxation could be effectively treated within the open - resonator framework ( see , e.g. , @xcite ) .
finally , it should be also noted that for some of the systems considered above there exist alternative _ ad hoc _ methods of description .
for instance , negative refraction and optical cloaking allow a natural representation in the geometrical formalism of general relativity @xcite .
we gratefully acknowledge partial support from the national security agency ( nsa ) , laboratory physical science ( lps ) , army research office ( aro ) , national science foundation ( nsf ) grant no .
eia-0130383 , jsps - rfbr 06 - 02 - 91200 , and core - to - core ( ctc ) program supported by japan society for promotion of science ( jsps ) .
k.b . acknowledges support from stcu grant p-307 and crdf grant uam2 - 1672-kk-06 .
s.s . acknowledges support from the ministry of science , culture and sport of japan via the grant - in aid for young scientists no 18740224 , the epsrc via no .
ep / d072581/1 , ep / f005482/1 , and esf network - programme `` arrays of quantum dots and josephson junctions '' . | superresolution , extraordinary transmission , total absorption , and localization of electromagnetic waves are currently attracting growing attention .
these phenomena are related to different physical systems and are usually studied within the context of different , sometimes rather sophisticated , approaches .
remarkably , all these seemingly unrelated phenomena owe their origin to the same underlying physical mechanism
wave interaction with an open resonator . here
we show that it is possible to describe all of these effects in a unified way , mapping each system onto a simple resonator model .
such description provides a thorough understanding of the phenomena , explains all the main features of their complex behavior , and enables to control the system via the resonator parameters : eigenfrequencies , q - factors , and coupling coefficients . |
chemotaxis , the directed movement of cells in response to chemical gradients , plays an important role in many biological fields , such as embryogenesis , immunology , cancer growth , and wound healing @xcite . at the macroscopic level ,
chemotaxis models can be formulated in terms of the cell density @xmath0 and the concentration of the chemical signal @xmath1 .
a classical model to describe the time evolution of these two variables is the ( patlak- ) keller - segel system , suggested by patlak in 1953 @xcite and keller and segel in 1970 @xcite . assuming that the time scale of the chemical signal is much larger than that of the cell movement , the classical parabolic - elliptic keller - segel equations read as follows : @xmath2 where @xmath3 is a bounded domain or @xmath4 , with homogeneous neumann boundary and initial conditions .
the parameter @xmath5 is the secretion rate at which the chemical substance is emitted by the cells .
the nonlinear term @xmath6 models the cell movement towards higher concentrations of the chemical signal .
this model exhibits the phenomenon of cell aggregation .
the more cells are aggregated , the more the attracting chemical signal is produced by the cells .
this process is counterbalanced by cell diffusion , but if the cell density is sufficiently large , the nonlocal chemical interaction dominates diffusion and results in a blow - up of the cell density . in two space dimensions , the critical threshold for blow - up
is given by @xmath7 if @xmath8 is a bounded connected domain with @xmath9 boundary @xcite and @xmath10 in the radial and whole - space case @xcite .
the existence and uniqueness of smooth global - in - time solutions in the subcritical case is proved for bounded domains in @xcite and in the whole space in @xcite . in the critical case @xmath10 ,
a global whole - space solution exists , which becomes unbounded as @xmath11 @xcite .
furthermore , there exist radially symmetric initial data such that , in the supercritical case , the solution forms a @xmath12-singularity in finite time @xcite . motivated by numerical and modeling issues , the question how blow up can be avoided has been investigated intensively the last years .
it has been suggested to modify the chemotactic sensitivity ( modeling , e.g. , volume - filling effects ) , to allow for degenerate cell diffusion , or to include suitable growth - death terms .
we refer to @xcite for references .
another idea is to introduce additional cell diffusion in the equation for the chemical concentration @xcite .
this diffusion term avoids , even for arbitrarily small diffusion constants , the blow - up and leads to the global - in - time existence of weak solutions @xcite .
the model , which is investigated in this paper , reads as follows : @xmath13 where @xmath14 is the additional diffusion constant .
we impose the homogeneous neumann boundary and initial conditions @xmath15 the advantage of the additional diffusion term is that blow - up of solutions is translated to large gradients which may help to determine the blow - up time numerically .
another advantage is that the enlarged system exhibits an interesting entropy structure ( see below ) . at first sight
, the additional term @xmath16 seems to complicate the mathematical analysis .
indeed , the resulting diffusion matrix of the system is neither symmetric nor positive definite , and we can not apply the maximum principle to the equation for the chemical signal anymore . it was shown in @xcite that all these difficulties can be resolved by the observation that the above system possesses a logarithmic entropy , @xmath17 which is dissipated according to @xmath18 suitable gagliardo - nirenberg inequalities applied to the right - hand side lead to gradient estimates for @xmath19 and @xmath20 , which are the starting point for the global existence and long - time analysis . in this paper
, we aim at developing a finite volume scheme which preserves the entropy structure on the discrete level by generalizing the scheme proposed in @xcite .
in contrast to @xcite , we are able to prove the existence of discrete solutions and their numerical convergence to the continuous solution for all values of the initial mass . moreover , we show that the discrete solution converges for large times to the homogeneous steady state if @xmath21 or @xmath22 are sufficiently small , using a new discrete logarithmic sobolev inequality ( proposition [ prop.dlsi ] ) . in the literature
, there exist several approaches to solve the classical keller - segel system numerically .
the parabolic - elliptic model was approximated by using finite difference @xcite or finite element methods @xcite .
also a dynamic moving - mesh method @xcite , a variational steepest descent approximation scheme @xcite , and a stochastic particle approximation @xcite were developed . concerning numerical schemes for the parabolic - parabolic model ( in which @xmath23 is added to the second equation in ) , we mention the second - order central - upwind finite volume method of @xcite , the discontinuous finite element approach of @xcite , and the conservative finite element scheme of @xcite .
we also cite the paper @xcite for a mixed finite element discretization of a keller - segel model with nonlinear diffusion .
there are only a few works in which a numerical analysis of the scheme was performed .
filbet proved the existence and numerical convergence of finite volume solutions @xcite .
error estimates for a conservative finite element approximation were shown by saito @xcite .
epshteyn and izmirlioglu proved error estimates for a fully discrete discontinuous finite element method @xcite .
convergence proofs for other schemes can be found in , e.g. , @xcite .
this paper contains the first numerical analysis for the keller - segel model with additional cross - diffusion .
its originality comes from the fact that we `` translate '' all the analytical properties of @xcite on a discrete level , namely positivity preservation , mass conservation , entropy stability , and entropy dissipation ( under additional hypotheses ) .
the paper is organized as follows .
section [ sec.main ] is devoted to the description of the finite volume scheme and the formulation of the main results .
the existence of a discrete solution is shown in section [ sec.ex ] .
a discrete version of the entropy - dissipation relation and corresponding gradient estimates are proved in section [ sec.est ] .
these estimates allow us to obtain in section [ sec.conv ] the convergence of the discrete solution to the continuous one when the approximation parameters tend to zero .
a proof of the discrete logarithmic sobolev inequality is given in section [ sec.dlsi ] .
the long - time behavior of the discrete solution is investigated in section [ sec.long ] .
finally , we present some numerical examples in section [ sec.num ] and compare the discrete solutions to our model with those computed from the classical keller - segel system .
in this section , we introduce the finite volume scheme and present our main results .
let @xmath3 be an open , bounded , polygonal subset .
an admissible mesh of @xmath8 is given by a family @xmath24 of control volumes ( open and convex polygons ) , a family @xmath25 of edges , and a family of points @xmath26 which satisfy definition 9.1 in @xcite .
this definition implies that the straight line between two neighboring centers of cells @xmath27 is orthogonal to the edge @xmath28 .
for instance , voronoi meshes are admissible meshes ( * ? ? ? * example 9.2 ) .
triangular meshes satisfy the admissibility condition if all angles of the triangles are smaller than @xmath29 ( * ? ? ?
* example 9.1 ) .
we distinguish the interior edges @xmath30 and the boundary edges @xmath31 .
the set of edges @xmath25 equals the union @xmath32 . for a control volume @xmath33 ,
we denote by @xmath34 the set of its edges , by @xmath35 the set of its interior edges , and by @xmath36 the set of edges of @xmath37 included in @xmath38 .
furthermore , we denote by d the distance in @xmath39 and by m the lebesgue measure in @xmath39 or @xmath40 .
we assume that the family of meshes satisfies the following regularity requirement : there exists @xmath41 such that for all @xmath33 and all @xmath42 with @xmath28 , it holds @xmath43 this hypothesis is needed to apply discrete sobolev - type inequalities @xcite . introducing for @xmath44 the notation @xmath45 we define
the transmissibility coefficient @xmath46 the size of the mesh is denoted by @xmath47 let @xmath48 be some final time and @xmath49 the number of time steps . then the time step size and the time points are given by , respectively , @xmath50 we denote by @xmath51 an admissible space - time discretization of @xmath52 composed of an admissible mesh @xmath24 of @xmath53 and the values @xmath54 and @xmath55 .
the size of this space - time discretization @xmath56 is defined by @xmath57 .
let @xmath58 be the linear space of functions @xmath59 which are constant on each cell @xmath33 .
we define on @xmath58 the discrete @xmath60 norm , discrete @xmath61 seminorm , and discrete @xmath61 norm by , respectively , @xmath62 @xmath63 where @xmath64 , @xmath65 , and @xmath66 for @xmath67 .
we are now in the position to define the finite volume discretization of - .
let @xmath51 be a finite volume discretization of @xmath68 .
the initial datum @xmath69 is approximated by its @xmath70 projection on control volumes : @xmath71 and @xmath72 is the characteristic function on @xmath37 . denoting by @xmath73 and @xmath74 approximations of the mean value of @xmath75 and @xmath76 on @xmath37 , respectively
, the numerical scheme reads as follows : @xmath77 for all @xmath33 and @xmath78 . here , @xmath79 , @xmath80 , and @xmath81 the approximation @xmath82 is computed from with @xmath83 .
this scheme is based on a fully implicit euler discretization in time and a finite volume approach for the volume variable .
the implicit scheme allows us to establish discrete entropy - dissipation estimates which would not be possible with an explicit scheme .
this approximation is similar to that in @xcite except the additional cross - diffusion term in the second equation .
the numerical approximations @xmath84 and @xmath85 of @xmath86 and @xmath20 are defined by @xmath87,\ ] ] and @xmath88 .
furthermore , we define approximations @xmath89 and @xmath90 of the gradients of @xmath86 and @xmath20 , respectively . to this end , we introduce a dual mesh : for @xmath33 and @xmath91 , let @xmath92 be defined by : * if @xmath93 , @xmath92 is the cell ( `` diamond '' ) whose vertices are given by @xmath94 , @xmath95 , and the end points of the edge @xmath28 . * if @xmath96 , @xmath92 is the cell ( `` triangle '' ) whose vertices are given by @xmath94 and the end points of the edge @xmath28 .
an example of construction of @xmath97 can be found in @xcite .
clearly , @xmath92 defines a partition of @xmath8 .
the approximate gradient @xmath89 is a piecewise constant function , defined in @xmath98 by @xmath99 where @xmath100 is given as in and @xmath101 is the unit vector normal to @xmath102 and outward to @xmath37 .
the approximate gradient @xmath90 is defined in a similar way .
our first result is the existence of solutions to the finite volume scheme .
[ thm.ex ] let @xmath3 be an open , bounded , polygonal subset and let @xmath103 be an admissible discretization of @xmath104 .
the initial datum satisfies @xmath105 , @xmath106 in @xmath8
. then there exists a solution @xmath107 to - satisfying @xmath108 properties and show that the scheme is positivity preserving and mass conserving .
it is also entropy stable ; see below .
let @xmath109 be a sequence of admissible space - time discretizations indexed by the size @xmath110 of the discretization .
we denote by @xmath111 the corresponding meshes of @xmath8 .
we suppose that these discretizations satisfy uniformly in @xmath112 , i.e. , @xmath41 does not depend on @xmath112 .
let @xmath113 be a finite volume solution , constructed in theorem [ thm.ex ] , on the discretization @xmath114 .
we set @xmath115 .
our second result concerns the convergence of @xmath116 to a weak solution @xmath117 to - .
[ thm.conv ] let the assumptions of theorem [ thm.ex ] hold . furthermore , let @xmath109 be a sequence of admissible discretizations satisfying uniformly in @xmath112 , and let @xmath116 be a sequence of finite volume solutions to -
. then there exists @xmath117 such that , up to a subsequence , @xmath118 and @xmath119 is a weak solution to - in the sense of @xmath120 for all test functions @xmath121)$ ] .
it is shown in ( * ? ? ?
* theorem 1.3 ) that , if the secretion rate @xmath5 is sufficiently small or the diffusion parameter @xmath14 is sufficiently large , the solution @xmath117 to - converges exponentially fast to the homogeneous steady state @xmath122 , where @xmath123 and @xmath124 .
the proof in @xcite is based on the logarithmic sobolev inequality .
therefore , we state first a novel discrete version of this inequality , which is proved in section [ sec.dlsi ] .
[ prop.dlsi ] let @xmath125 @xmath126 be an open bounded polyhedral domain and let @xmath24 be an admissible mesh of @xmath8 satisfying .
then there exists a constant @xmath127 only depending on @xmath8 , @xmath128 , and @xmath129 such that for all @xmath64 , @xmath130 where we abbreviated @xmath131 .
the constant @xmath127 can be made more precise .
let @xmath132 be the constant in the discrete sobolev inequality ( * ? ? ?
* theorem 4 ) @xmath133 where @xmath134 ( and @xmath135 if @xmath136 ) , and let @xmath137 be the constant in the discrete poincar - wirtinger inequality ( * ? ? ?
1 ) @xmath138 where @xmath139 and @xmath140 , @xmath131 .
then @xmath141 for our result on the long - time behavior , we introduce the discrete relative entropy @xmath142 = \sum_{k\in{\mathcal{t}}}{\text{\rm m}}(k)n_k^k\log\left(\frac{n_k^k}{n^*}\right)\ge 0 , \quad k\ge 0.\ ] ] [ thm.long ] let the assumptions of theorem [ thm.ex ] hold and let @xmath143 be a solution to - .
then for all @xmath144 , @xmath145 + \delta t(1-c^*)\big|\sqrt{n^{k+1}}\big|_{1,2,{\mathcal{t}}}^2 + \frac{\delta t}{2\delta}\|s^{k+1}-s^*\|_{1,2,{\mathcal{t}}}^2 \le e[n^k|n^*],\ ] ] where @xmath146 , @xmath147 only depending on @xmath8 , and @xmath129 is the parameter in .
in particular , if @xmath148 , the discrete relative entropy is nonincreasing and @xmath149\|n_0\|_{l^1(\omega ) } } \left(1+\frac{1-c^*}{c_l}\delta t \right)^{-k/2 } , \\ \|s^k - s^*\|_{1,2,{\mathcal{t } } } & \le \sqrt{\frac{2\delta e[n^0|n^{*}]}{\delta t } } \left(1+\frac{1-c^*}{c_l}\delta t \right)^{-(k-1)/2 } , \quad k\in{{\mathbb n}},\end{aligned}\ ] ] where @xmath127 is the constant in the discrete logarithmic sobolev inequality ( see proposition [ prop.dlsi ] ) . in particular , for each @xmath33 , @xmath150 in @xcite , the long - time behavior of solutions is shown under the condition @xmath151 for a constant @xmath147 appearing in some poincar - sobolev inequality .
we observe that our condition depends additionally on the regularity of the finite volume mesh .
the convergence of @xmath152 is approximately exponential for sufficiently small @xmath153 .
the convergence result for @xmath154 is weaker in view of the factor @xmath155 . in @xcite , the exponential convergence of @xmath156
is shown in the @xmath157 norm only and therefore , our result is not surprising .
in this section , we prove theorem [ thm.ex ] . the proof is based on the brouwer fixed - point theorem .
let @xmath158 and let @xmath159 be a solution to and , with @xmath160 replaced by @xmath161 , satisfying - .
we introduce the set @xmath162 the finite - dimensional space @xmath163 is convex and compact . in the following ,
we define the fixed - point operator by solving a linearized problem .
first , we construct @xmath164 using the following scheme : @xmath165 second , we compute @xmath166 using the scheme @xmath167 _ step 1 : existence and uniqueness for and . _
the linear system can be written as @xmath168 , where @xmath169 is the matrix with the elements @xmath170 and @xmath171 is the vector with the elements @xmath172 since for all @xmath173 , @xmath174 the matrix @xmath169 is strictly diagonally dominant with respect to the columns and hence , @xmath169 is invertible .
this shows the unique solvability of .
similarly , can be written as @xmath175 , where @xmath176 is the matrix with the elements @xmath177 and @xmath178 is the vector with the elements @xmath179 , @xmath33 .
the diagonal elements of @xmath176 are positive , and the off - diagonal elements are nonpositive .
moreover , @xmath176 is strictly diagonal dominant with respect to the columns since for all @xmath93 , we have @xmath180 which yields @xmath181 and hence , @xmath182 we infer that @xmath176 is an m - matrix and invertible , which gives the existence and uniqueness of a solution @xmath183 to .
the m - matrix property of @xmath176 implies that @xmath184 is positive . as a consequence ,
since @xmath185 and @xmath178 are nonnegative componentwise , by the induction hypothesis , @xmath186 is nonnegative componentwise .
this means that @xmath183 satisfies . summing over @xmath33
, we compute @xmath187 _ step 2 : continuity of the fixed - point operator . _ the solution to and defines the fixed - point operator @xmath188 , @xmath189 .
we have to show that @xmath190 is continuous .
for this , let @xmath191 be a sequence converging to @xmath86 in @xmath58 as @xmath192 .
setting @xmath193 and @xmath194 , we have to prove that @xmath195 in @xmath58 . using the scheme ,
we construct first @xmath196 ( respectively , @xmath197 ) from @xmath198 ( respectively , @xmath86 ) .
then , using the scheme , we obtain @xmath199 ( respectively , @xmath183 ) .
we claim that @xmath200 in @xmath58 as @xmath192 . indeed , since the map @xmath201 , where @xmath202 is constructed from , is linear on the finite dimensional space @xmath58 , it is obviously continuous .
moreover , using the scheme and performing the same computations as in the proof of theorem 2.1 in @xcite , it follows that @xmath203 the right - hand side converges to zero as @xmath204 in @xmath58 , which proves that @xmath205 in @xmath58 .
_ step 3 : application of the fixed - point theorem . _
the assumptions of the brouwer fixed - point theorem are satisfied , implying the existence of a fixed point of @xmath190 , i.e. of a solution @xmath206 to satisfying .
we have shown in step 1 that holds for @xmath206 .
finally , we construct @xmath207 using scheme .
the proof of theorem [ thm.conv ] is based on suitable a priori estimates which are shown in this section .
we introduce a discrete version of the entropy functional used in @xcite : @xmath208 [ prop.ent ] there exists a constant @xmath209 only depending on @xmath8 , @xmath21 , @xmath12 , @xmath210 , and @xmath129 ( see ) such that for all @xmath144 , @xmath211 by the convexity of @xmath212 , we find that @xmath213 inserting the scheme , we can write @xmath214 now , we argue similarly as in the proof of lemma 3.1 in @xcite . we employ the symmetry of @xmath215 and a taylor expansion of @xmath216 around @xmath217 to infer that @xmath218 where @xmath219 for some @xmath220 .
we perform a summation by parts in @xmath221 , using again the symmetry of @xmath215 : @xmath222 reordering the sum and using the expression for @xmath223 in the taylor expansion of log , it is shown in @xcite that @xmath224 the taylor expansion shows that @xmath225 , which gives @xmath226 summarizing the estimates for @xmath227 and @xmath221 , leads to @xmath228 the first term can be estimated for @xmath28 as follows : @xmath229 in order to bound the second term , we multiply the scheme by @xmath230 and sum over @xmath33 : @xmath231 by summation by parts , we find that @xmath232 inserting into and employing , it follows that @xmath233 it remains to estimate the right - hand side .
we follow the proof of proposition 3.1 in @xcite .
the hlder inequality yields @xmath234 the discrete @xmath235 norm of @xmath207 can be bounded by the discrete @xmath236 norm using the discrete sobolev inequality @xmath237 where @xmath209 depends only on @xmath8 and @xmath129 . for the discrete @xmath238 norm of @xmath206
, we employ the discrete gagliardo - nirenberg inequality ( * ? ? ?
* theorem 3 ) with @xmath239 : @xmath240 where @xmath209 depends only on @xmath8 and @xmath129 .
mass conservation implies that @xmath241 with these estimates , becomes @xmath242 then , by young s inequality with @xmath243 , @xmath244 , @xmath245 , @xmath246 together with , this finishes the proof .
summing over @xmath88 and using the mass conservation , we conclude immediately the following @xmath112-uniform bounds for the family of solutions @xmath247 to - with discretizations @xmath114 : @xmath248 [ prop.bound ] the family @xmath249 is bounded in @xmath250 .
first , we claim that @xmath251 is bounded in @xmath252 .
to simplify the notation , we write @xmath253 . applying the cauchy - schwarz inequality , we obtain @xmath254 observe that in two space dimensions , @xmath255 since the straight line between @xmath94 and @xmath95 is orthogonal to the edge @xmath28 . using this property , the mesh regularity assumption , and the mass conservation , it follows that @xmath256 in view of the entropy stability estimate , we infer that @xmath251 is bounded in @xmath257 @xmath258 .
because of the discrete sobolev inequality ( * ? ? ?
* theorem 4 ) , @xmath259 the family @xmath251 is bounded in @xmath260 . in order to estimate the approximate gradient of @xmath261
, we employ .
the last term in is treated as follows .
we multiply by @xmath262 , sum over @xmath33 , and sum by parts : @xmath263 inserting this estimate into , we infer that @xmath264 summing this inequality over @xmath88 and observing that the right - hand side is uniformly bounded , we conclude that @xmath265 is bounded in @xmath260 , which finishes the proof .
we prove theorem [ thm.conv ] .
consider the family @xmath247 of approximate solutions to - . in order to apply compactness results ,
we need to control the difference @xmath266 . to this end , let @xmath267 , where @xmath268 .
we denote by @xmath269 the average of @xmath270 in the control volume @xmath37 . using scheme and the notation @xmath271 , @xmath272 where @xmath209 only depends on @xmath8 . summing over @xmath88 and employing hlder s inequality ,
the uniform bound on @xmath261 from proposition [ prop.bound ] and on @xmath273 from imply the existence of a constant @xmath209 , independent of @xmath112 , such that @xmath274 now , similarly as in the proof of lemma 10.6 in @xcite , for all @xmath275 , @xmath276 where @xmath277 , \\ 0 & \quad\mbox{if } k\delta t\not\in(t , t+\tau ] .
\end{array}\right.\ ] ] inserting into the above inequality and observing that @xmath278 we infer that @xmath279 this gives a uniform estimate for the time translations of @xmath261 in @xmath280 .
since the embedding @xmath281 is compact for all @xmath65 in two space dimensions , we conclude from the discrete aubin lemma @xcite that there exists a subsequence of @xmath251 , not relabeled , such that , as @xmath282 , @xmath283 furthermore , since @xmath265 is bounded in @xmath260 , there exists @xmath284 such that @xmath285 it is shown in the proof of lemma 4.4 in @xcite that @xmath286 in the sense of distributions .
the bound of @xmath287 in @xmath250 implies the existence of a subsequence , which is not relabeled , such that @xmath288 again , it follows that @xmath289 in the sense of distributions .
the limit @xmath282 in the scheme - is performed exactly as in the proofs of propositions 4.2 and 4.3 in @xcite , using the above convergence results and the fact that @xmath290 converges weakly to @xmath6 in @xmath291 .
compared to @xcite , we have to pass to the limit also in the additional cross - diffusion term which does not give any difficulty since this term is linear in @xmath261 .
this shows that @xmath117 solves the weak formulation - , finishing the proof .
the proof follows ( * ? ? ?
* lemma 2.1 ) .
set @xmath292 where @xmath131 and @xmath293 . then @xmath294 and @xmath295 .
using jensen s inequality for the ( probability ) measure @xmath296 , we find that for @xmath297 , @xmath298 because of @xmath299 for @xmath300 . with the definition of @xmath301 ,
this inequality becomes @xmath302 by the discrete sobolev inequality , we infer that for @xmath303 ( and @xmath304 if @xmath305 ) @xmath306 inequality ( 4.2.19 ) in @xcite ( adapted to domains with general measure ) shows that @xmath307 hence , with the discrete poincar inequality , @xmath308 and proposition [ prop.dlsi ] follows .
in this section , we prove theorem [ thm.long ] . similarly as in the proof of proposition [ prop.ent ] ( see and ) , we have @xmath309&-e[n^k|n^ * ] = \sum_{k\in{\mathcal{t}}}{\text{\rm m}}(k)(h(n_k^{k+1})-h(n_k^k ) ) \nonumber \\ & \le -\delta t\sum_{\substack{\sigma\in{\mathcal{e}}_{\rm int},\\ \sigma = k|l } } \tau_\sigma\big|d\big(\sqrt{n^{k+1}}\big)_{k,\sigma}\big|^2 + \delta t\sum_{\substack{\sigma\in{\mathcal{e}}_{\rm int},\\ \sigma = k|l } } \tau_\sigma ds_{k,\sigma}^{k+1}dn_{k,\sigma}^{k+1}. \label{aux7}\end{aligned}\ ] ] in view of the identity @xmath124 , we can formulate the scheme for all @xmath33 as @xmath310 multiplying this equation by @xmath311 and summing over @xmath33 gives @xmath312 replacing the last term in by the above equation and using the cauchy - schwarz and young inequalities , it follows that @xmath309-e[n^k|n^ * ] & + \delta t\big|\sqrt{n^{k+1}}\big|_{1,2,{\mathcal{t}}}^2 + \frac{\delta t}{\delta}\|s^{k+1}-s^*\|_{1,2,{\mathcal{t}}}^2 \\ & = \frac{\mu\delta t}{\delta}\sum_{k\in{\mathcal{t}}}{\text{\rm m}}(k)(n_k^{k+1}-n^*)(s_k^{k+1}-s^ * ) \\ & \le \frac{\mu^2\delta t}{2\delta}\|n^{k+1}-n^*\|_{0,2,{\mathcal{t}}}^2 + \frac{\delta t}{2\delta}\|s^{k+1}-s^*\|_{0,2,{\mathcal{t}}}^2.\end{aligned}\ ] ] the second term on the right - hand side can be absorbed by the corresponding expression on the left - hand side . for the first term , we employ the continuous embedding of @xmath313 into @xmath314 in dimension 2 and the definition of the seminorm @xmath315 ( * ? ? ?
* theorem 2 ) : @xmath316 then , using inequality , we can estimate : @xmath317 setting @xmath146 , this yields @xmath145-e[n^k|n^ * ] + \delta t(1-c^*)\big|\sqrt{n^{k+1}}\big|_{1,2,{\mathcal{t}}}^2 + \frac{\delta t}{2\delta}\|s^{k+1}-s^*\|_{1,2,{\mathcal{t}}}^2 \le 0.\ ] ] to proceed , we assume that @xmath318 . with the discrete logarithmic sobolev inequality ( proposition [ prop.dlsi ] ) , @xmath145 \le c_l|\sqrt{n^{k+1}}|_{1,2,{\mathcal{t}}}^2,\ ] ] we infer that @xmath319\left(1+\frac{1-c^*}{c_l}\delta t\right)-e[n^k|n^ * ] + \frac{\delta t}{2\delta}\|s^{k+1}-s^*\|_{1,2,{\mathcal{t}}}^2 \le 0,\ ] ] and hence , @xmath320
\le \left(1+\frac{1-c^*}{c_l}\delta t\right)^{-k } e[n^0|n^*].\ ] ] then , by the csiszr - kullback inequality ( * ? ? ?
3.1 ) ( this result is valid in bounded domains too ) , @xmath321 \le 4\|n_0\|_{l^1(\omega ) } \left(1+\frac{1-c^*}{c_l}\delta t\right)^{-k } e[n^0|n^*].\ ] ] going back to , we find that @xmath322 \le \frac{2\delta}{\delta t}\left(1+\frac{1-c^*}{c_l}\delta t\right)^{-k } e[n^0|n^*],\ ] ] which concludes the proof .
in this section , we investigate the numerical convergence rates and give some examples illuminating the long - time behavior of the finite volume solutions to nonhomogeneous steady states .
we compute first the spatial convergence rate of the numerical scheme .
we consider the system on the square @xmath323 .
the time step is chosen to be @xmath324 , and the final time is @xmath325 .
the initial data is the gaussian @xmath326 where @xmath327 , @xmath328 , and @xmath329 .
the model parameters are @xmath330 and @xmath331 .
we compute the numerical solution on a sequence of square meshes . the coarsest mesh is composed of @xmath332 squares . the sequence of meshes is obtained by dividing successively the size of the squares by 4 .
then , the finest grid is made of @xmath333 squares .
the @xmath60 error at time @xmath334 is given by @xmath335 where @xmath336 represents the approximation of the cell density computed from a mesh of size @xmath337 and @xmath338 is the `` exact '' solution computed from a mesh with @xmath333 squares ( and with @xmath324 ) .
the numerical scheme is said to be of order @xmath339 if for all sufficiently small @xmath340 , it holds that @xmath341 for some constant @xmath209 .
figure [ fig.cr ] shows that the convergence rates in the @xmath342 , @xmath70 , and @xmath343 norms are around one .
as expected , the scheme is of first order . according to theorem [ thm.long ]
, the solution to the keller - segel system converges to the homogeneous steady state if @xmath21 or @xmath22 are sufficiently small .
we will verify this property experimentally .
to this end , let @xmath323 and @xmath346 where @xmath327 and @xmath347 .
we compute the approximate solution on a @xmath348 cartesian grid , and we choose @xmath349 . in figure
[ fig.ent1 ] , we depict the temporal evolution of the relative entropy @xmath350 $ ] in semi - logarithmic scale . in all cases shown , the convergence seems to be of exponential rate .
the rate becomes larger for larger values of @xmath12 or smaller values of @xmath21 which is in agreement with estimate .
in fact , the constant @xmath351 is proportional to @xmath352 ( see theorem [ thm.long ] ) and the rate improves if @xmath352 is smaller . as a numerical check , we computed the evolution of the relative entropies for different grid sizes @xmath353 and different time step sizes @xmath354 .
figure [ fig.ent2 ] shows that the decay rate does not depend on the time step or the mesh considered . in this subsection
, we explore the behavior of the solutions to for different values of @xmath12 .
we choose @xmath323 with a @xmath355 cartesian grid , @xmath331 , and @xmath356 .
we consider two nonsymmetric initial functions with mass @xmath357 : @xmath358 where @xmath327 , @xmath329 , and @xmath359 ( see figure [ fig.init ] ) .
we consider first the case @xmath360 , which corresponds to the classical parabolic - elliptic keller - segel system . in this case ,
our finite volume scheme coincides with that of @xcite .
we recall that solutions to the classical parabolic - elliptic model blow up in finite time if the initial mass satisfies @xmath361 @xcite ( in the non - radial case ) .
the numerical results at a time just before the numerical blow - up are presented in figure [ fig.nonsymm.0 ] .
we observe the blow - up of the cell density in finite time , and the blow - up occurs at the boundary , as expected .
more precisely , it occurs at that corner which is closest to the global maximum of the initial datum .
next , we choose @xmath330 and @xmath362 .
according to theorem [ thm.ex ] , the numerical solution exists for all time .
this behavior is confirmed in figure [ fig.nonsymm.23 ] , where we show the cell density at time @xmath363 . at this time , the solution is very close to the steady state which is nonhomogeneous .
we observe a smoothing effect of the cross - diffusion parameter @xmath12 ; the cell density maximum decreases with increasing values of @xmath12 .
we consider , as in the previous subsection , the domain @xmath323 with a @xmath355 cartesian grid , @xmath331 , and @xmath364 . here , we consider the radially symmetric initial datum @xmath365 with @xmath366 and @xmath327 . since @xmath367 and
the initial datum is radially symmetric , we expect that the solution to the classical keller - segel model ( @xmath360 ) blows up in finite time @xcite .
figure [ fig.symm.0 ] shows that this is indeed the case , and blow - up occurs in the center of the domain .
in contrast to the classical keller - segel system , when taking @xmath330 , the cell density peak moves to a corner of the domain and converges to a nonhomogeneous steady state ( see figure [ fig.symm.3 ] ) .
the time evolution of the @xmath343 norm of the cell density shows an interesting behavior ( see figure [ fig.symm.linfty ] ) .
we observe two distinct levels .
the first one is reached almost instantaneously .
the @xmath343 norm stays almost constant and the cell density seems to stabilize at an intermediate symmetric state ( figure [ fig.symm.3]a ) .
after some time , the @xmath343 norm increases sharply and the cell density peak moves to the boundary ( figure [ fig.symm.3]b ) .
then the solution stabilizes again ( figure [ fig.symm.3]c ) .
we note that we obtain the same steady state when using a gaussian centered at @xmath370 .
we consider the domain @xmath371 @xmath372 and compute the approximate solutions on a @xmath373 cartesian grid with @xmath374 .
the secretion rate is again @xmath331 , and we choose the initial data @xmath375 and @xmath376 , defined in - with mass @xmath377 .
if @xmath360 , the solution blows up in finite time and the blow up occurs in a corner as in the square domain ( see figure [ fig.nonsymm.r0 ] ) . if @xmath330 , the approximate solutions converge to a non - homogeneous steady state ( figure [ fig.nonsymm.r3 ] ) .
interestingly , before moving to the corner , the solution evolving from the nonsymmetric initial datum @xmath376 shows some intermediate behavior ; see figure [ fig.nonsymm.r3]b .
the domain is still the rectangle @xmath378 , we take a @xmath373 cartesian grid , @xmath331 , and @xmath364 .
we choose the initial datum @xmath368 , defined in , with @xmath366 .
clearly , the approximate solution to the classical keller - segel model @xmath360 blows up in finite time in the center @xmath379 of the rectangle .
when @xmath330 , the cell density peak first moves to the closest boundary point before moving to a corner of the domain , as in the square domain ( figure [ fig.symm.r ] ) .
however , in contrast to the case of a square domain , there exist _ two _ intermediate states , one up to time @xmath380 and another in the interval @xmath381 , and one final state for long times ( see figure [ fig.symm.rl ] ) .
we note that the same qualitative behavior is obtained using @xmath362 .
c. budd , r. carretero - gonzlez , and r. russell .
precise computations of chemotactic collapse using moving mesh methods .
_ j. comput .
_ 202 ( 2005 ) , 463 - 487 . m. burger , j. a. carrillo , and m .-
wolfram . a mixed finite element method for nonlinear diffusion equations .
_ kinetic related models _ 3 ( 2010 ) , 59 - 83 .
a. guionnet and b. zegarlinski .
lectures on logarithmic sobolev inequalities . in : j. azma
( eds . ) , _ sminaire de probabilits _ , vol . 36 , pp . 1 - 134 , lect . notes math .
1801 , springer , berlin , 2003 . | a finite volume scheme for the ( patlak- ) keller - segel model in two space dimensions with an additional cross - diffusion term in the elliptic equation for the chemical signal is analyzed .
the main feature of the model is that there exists a new entropy functional yielding gradient estimates for the cell density and chemical concentration .
the main features of the numerical scheme are positivity preservation , mass conservation , entropy stability , and under additional assumptions entropy dissipation . the existence of a discrete solution and its numerical convergence to the continuous solution is proved .
furthermore , temporal decay rates for convergence of the discrete solution to the homogeneous steady state is shown using a new discrete logarithmic sobolev inequality .
numerical examples point out that the solutions exhibit intermediate states and that there exist nonhomogeneous stationary solutions with a finite cell density peak at the domain boundary . |
meningiomas constitute approximately 20% of all brain tumors8 ) . in 1922 , harvey cushing first used the term meningioma16 ) . according to the world health organization ( who ) histologic grading system , three grades of meningiomas with increasing risks of recurrence are distinguished8 ) . benign or common - type tumors with a low rate of recurrence ( 7 - 20% )
are assigned to grade i. grade ii meningiomas include atypical meningiomas as well as the rare chordoid and clear cell ( intracranial ) variants , and exhibit a higher risk of recurrence ( 29 - 40% ) . grade iii meningiomas are anaplastic meningiomas with high mitotic activity ( 20/10 high - power fields ) and/or obviously malignant cytology , as well as the rare variants , papillary and rhabdoid meningiomas .
the recurrence rate of anaplastic meningiomas is suggested to be 50 - 78% . whereas a retrospective review showed that resections of who grade ii meningiomas are less often classified by surgeons as gross total when compared with benign meningiomas , a majority of who grade ii meningiomas are still able to undergo gross total resection ( gtr ) as the initial treatment17 ) . the subsequent prognosis and optimal management after gtr of who grade ii meningiomas remain unclear .
we sought to define the long - term recurrence rate and predictive factors for recurrence of who grade ii meningiomas .
between 1993 and 2005 , 448 patients with an intracranial meningioma were treated surgically at our institution by one surgeon .
the mean duration of follow - up was 45 months ( range , 3 - 175 months ) .
twenty - eight tumors had undergone simpson grade i ( complete ) resection , as confirmed by both the surgeon 's impression at the time of surgery and the first post - operative imaging scans .
this study was approved by the institutional review board at our institution . the patient and tumor characteristics of 55 who grade ii meningiomas are summarized in table 1 .
age at the time of diagnosis was defined as the patient 's age at the time of his or her first surgery .
tumor size was defined by the largest tumor diameter rounded to the nearest centimeter on imaging scans before the initial surgery .
the tumors were sub - grouped according to location , as follows : convexity ; parasagittal ; falx ; sphenoid ridge ; cerebellopontine angle ; tuberculum sellae ; olfactory groove ; and tentorium ( table 2 ) . "
complete resection " is defined as simpson grade i , and " incomplete resection " is defined as simpson grade ii , iii , or iv .
the meningiomas were also divided into groups , as follows : convexity and non - convexity groups .
the anatomic distribution of the 55 meningiomas that were totally resected during this period differed in having a higher proportion of tumors in the " convexity " group ( 19 of 25 patients ) and a lower proportion in the " non - convexity " group ( 9 of 30 patients ) .
patients with completely resected who grade ii meningiomas who do not receive radiation therapy are observed closely in our institution .
we recommend post - operative radiation therapy in patients with grade ii meningiomas which are not completely resected . in recurrent cases
gamma knife radiosurgery is an alternative treatment modality in small or surgically inaccessible meningiomas or meningiomas , and patients of advanced age and poor operative risk .
logistic regression , mantel - cox , and breslow - gehan - wilcoxon univariate and multivariate models were used to compare the recurrence - free survival distributions across subgroups .
the following variable data were analyzed by multiple regression analysis with recurrence as the dependent variable : age ; gender ; tumor size ; peritumoral edema ; extent of tumor removal ; and tumor location .
between 1993 and 2005 , 448 patients with an intracranial meningioma were treated surgically at our institution by one surgeon .
the mean duration of follow - up was 45 months ( range , 3 - 175 months ) .
twenty - eight tumors had undergone simpson grade i ( complete ) resection , as confirmed by both the surgeon 's impression at the time of surgery and the first post - operative imaging scans .
this study was approved by the institutional review board at our institution . the patient and tumor characteristics of 55 who grade ii meningiomas are summarized in table 1 .
age at the time of diagnosis was defined as the patient 's age at the time of his or her first surgery .
tumor size was defined by the largest tumor diameter rounded to the nearest centimeter on imaging scans before the initial surgery .
the tumors were sub - grouped according to location , as follows : convexity ; parasagittal ; falx ; sphenoid ridge ; cerebellopontine angle ; tuberculum sellae ; olfactory groove ; and tentorium ( table 2 ) . "
complete resection " is defined as simpson grade i , and " incomplete resection " is defined as simpson grade ii , iii , or iv .
the meningiomas were also divided into groups , as follows : convexity and non - convexity groups .
the anatomic distribution of the 55 meningiomas that were totally resected during this period differed in having a higher proportion of tumors in the " convexity " group ( 19 of 25 patients ) and a lower proportion in the " non - convexity " group ( 9 of 30 patients ) .
patients with completely resected who grade ii meningiomas who do not receive radiation therapy are observed closely in our institution .
we recommend post - operative radiation therapy in patients with grade ii meningiomas which are not completely resected . in recurrent cases
gamma knife radiosurgery is an alternative treatment modality in small or surgically inaccessible meningiomas or meningiomas , and patients of advanced age and poor operative risk .
logistic regression , mantel - cox , and breslow - gehan - wilcoxon univariate and multivariate models were used to compare the recurrence - free survival distributions across subgroups .
the following variable data were analyzed by multiple regression analysis with recurrence as the dependent variable : age ; gender ; tumor size ; peritumoral edema ; extent of tumor removal ; and tumor location .
of the 448 patients , 20 had who grade iii meningiomas , 55 had who grade ii meningiomas , and 373 had benign meningiomas .
a multivariate analysis was then performed to assess the following eight variables as possible prognostic factors for tumor recurrence : 1 ) age ; 2 ) gender ; 3 ) tumor location ; 4 ) tumor size ; 5 ) peritumoral edema ; 6 ) post - operative radiation therapy ; 7 ) histologic type ; and 8) extent of resection . of these eight factors ,
three were predictive of recurrence based on multivariate analysis , as follows : pathologic subtype ( p=0.001 ) ; degree of resection ( p=0.001 ) ; and peritumoral edema ( p=0.016 ) .
the extent of resection was a significant independent predictive factor for who grade ii meningiomas ( p=0.05 ) ( table 3 ) .
of the 55 patients diagnosed with who grade ii meningiomas at our institution between 1993 and 2005 , 26 were men and 29 were women .
the mean age at the time of diagnosis was 55 years ( range , 19 - 82 years ) .
clinical follow - up included serial imaging for an average of 45 months after tumor resection ( range , 3 - 175 months ) with 40% of the patients followed either to recurrence or for at least 5 years after surgery . in who grade ii patients , 14 had recurrences 7 - 96 months post - operatively ; 11 patients had recurrences 5 years post - operatively ( mean time to recurrence , 42.9 months ) , and 3 had recurrences 10 years post - operatively .
complete resection was achieved in 28 patients and incomplete resection was achieved in 27 patients .
the recurrence rate between the two groups of ' who grade ii meningioma patients ( complete resection ) ' and ' who grade i meningioma patients ( complete or incomplete resection ) ' were 14.2% and 11.5% , respectively ( table 4 , fig . 1 , 2c ) .
although it was difficult to show statistical significance , the recurrence rates were similar between the benign meningioma treatment group and the who grade ii meningioma without radiotherapy treatment group ( p=0.844 ) .
however , the relative risk ( rr ) of recurrence was significantly higher for patients with who grade ii meningiomas with incomplete resections ( 10/27 , rr=37% ) than patients with complete resections ( 4/28 , rr=14% ) , independent of post - operative radiotherapy .
2b represents the recurrence - free survival between the two treatment groups ( p=0.05 ) . in the incomplete resection group
five of 7 patients had recurrences after post - operative radiotherapy ( table 4 ) .
we analyzed the recurrence - free survival between these two groups , but it was difficult to interpret the statistical significance of the influence of radiotherapy on recurrence ( p=0.314 ) .
when subdividing this group based on simpson grade , the simpson grade iii or iv group had a high risk of recurrence regardless of post - operative radiotherapy ( n=3 , rr=100% ) . however ,
if the degree of resection was simpson grade ii , the recurrence rate was similar to the complete resection group , although post - operative radiotherapy was not administered ( 3/18 , rr=15.5% ) .
table 5 shows the information regarding patients who did not receive radiotherapy after incomplete resection ; five patients had recurrences .
this group had distinguishing features from other groups . with the exception of one patient ,
all patients were in the non - convexity area , and in whom it was more difficult to perform complete resections than in patients in the convexity area .
most of the patients had moderate - to - severe degrees of peritumoral edema ; three of the patients had several recurrences .
we delivered post - operative radiotherapy to this patients who had more risky conditions for recurrence than other patients .
anatomically , there were higher proportions of convexity meningiomas in the completely resected group [ 67% ( 19/28 ) ] than in the incompletely resected group [ 22% ( 6/27 ) ] .
considering the importance of the degree of resection and post - operative radiation therapy , we compared the simpson grade i resection group without radiotherapy in convexity and simpson grade ii resection followed by post - operative radiotherapy group in non - convexity .
the recurrence rate was significantly higher in the latter ( 60% ) than the former ( 15% ) .
in this study , we sought to define the long - term recurrence rate of who grade ii meningiomas after complete or incomplete resection , as well as factors influencing recurrence , including post - operative radiation .
thus , we attempted to reveal what clinicopathologic features may be useful for predicting recurrence of who grade ii meningiomas .
it is well - known that the histologic type is a significant prognostic factor in overall meningiomas . in our study , according to the kaplan - meier survival analysis , the recurrence rate between the pathologic types was shown to be lowest in who grade i meningiomas and highest in who grade iii meningiomas ( fig .
the recurrence rate increased with the histologic grade rising , consistent with the findings of ayerbe et al.1 ) mantle et al.9 ) reported that meningiomas invade brain tissue along cells , forming bridges between the cortex and surface of the tumor .
mantle et al.9 ) suggested that the invasive cells were the main reason for tumor recurrence .
some authors state that tumor size may be helpful in predicting the recurrence of who grade ii meningioma14 ) . also , several studies reported that males have higher recurrence rate4,15 ) , and development of tumors in patients at a young age ( < 40 years ) was associated with higher likelihood of recurrence15 ) , although these were not clear in this or other studies7,12 ) . in the present study ,
the degree of peritumoral edema is a significant prognostic factor in overall meningiomas , but has no predictability for who grade ii meningiomas ( fig . 2d , table 3 ) .
some authors have reported statistical significance as predictive factors for recurrence of meningiomas20 ) because edema represent a variety of pathologic changes , such as a cerebral - pial vascular supply and cerebral white matter hypoperfusion13,18,20 ) .
the degree of resection as a significant independent predictive factor of recurrence in who grade ii meningiomas as well as in overall meningiomas , many authors had reported similar results .
mirimanoff et al.11 ) reported recurrence - free survival rates after total resection of 93% at 5 years , 80% at 10 years , and 68% at 15 years ; compared with partial resection , the recurrence - free survival rates dropped to 63% , 45% , and 9% , respectively12 ) .
jaaskelainen5 ) reported that after complete resection the recurrence rates were 19% at the 20-year follow - up .
the same group reported that in patients with atypical or malignant meningiomas after complete resection the risk of recurrence was 38% and 78% at 5 years , respectively6 ) .
goyal et al.3 ) reported that 8 of 22 patients had local recurrences , including 2 of 15 with gtr , 3 of 4 with str , and all 3 patients had resection of unknown extent . at 10 years , patients with gtr had a higher local control rate than those who had a str or a resection of unknown extent ( 87% vs. 17% ; p=0.02 ) .
the most important factors that determine the likelihood of meningioma recurrences is the extent of tumor resection .
although location was not a significant predictive factor for recurrence of meningiomas in our study , location is an important factor influencing the extent of resection of meningiomas .
convexity meningiomas are an indication for complete resection , simpson grade i can also identify complete resection most significantly than other locations .
we reasoned that comparing the two groups , simpson grade i resection without rt in the convexity group and simpson grade ii resection followed by post - operative radiotherapy in the non - convexity group was meaningful to minimize bias . for amplifying the clarity of the relationship between the extent of resection and recurrence considering the potential difficulty of radical resection in non - convexity , we compared two groups to the exclusion of the simpson grade iii or iv group ; the recurrence rate of the former was 15.7% and the recurrence rate of the latter was 60% .
it was reconfirmed that the extent of resection was a powerful factor for decreasing recurrence of who grade ii meningiomas .
post - operative adjuvant radiotherapy after surgical resection of who grade ii meningiomas continues to be controversial . in our study
furthermore , the incompletely resected group with radiotherapy had a higher recurrence rate than the group without radiotherapy .
in contrast to our expectations , some patients did well for many years after subtotal resections alone .
we presumed the cause of a higher recurrence rate was due to the fact that the patients had been expected to have a worse prognosis because of factors , such as severe edema or complex site or previous recurrence underwent radiotherapy ( table 5 ) .
most of the authors tend not to recommend adjuvant radiotherapy in grade i meningiomas . if gross total resection was achieved , however , there are significant variations in opinion about the effect of post - operative radiotherapy in cases of completely resected grade ii meningiomas10 ) therefore , we compared the recurrence rate between two groups ( the overall treatment group of benign meningiomas and the complete resection group of who grade ii meningiomas without radiotherapy ) .
although it was difficult to show statistical significance ( p=0.844 ) , the recurrence rate between the two groups were similar to each other ( table 4 , fig . 2c ) .
this suggests that complete resection of who grade ii meningiomas reduced the recurrence rate to that of who grade i meningiomas , regardless of post - operative radiotherapy .
however , in the completely resected group , the effect of post - operative radiation therapy was uncertain in this study .
we subdivided the incomplete resection group through simpson grade for researching the effect of post - operative radiotherapy .
the group performed by simpson grade iii or iv had a significantly high risk of recurrence without reference to post - operative radiotherapy .
if the degree of resection is simpson grade ii , the recurrence rate is similar to the complete resection group , although post - operative radiotherapy was not performed .
it is questionable whether or not post - operative radiotherapy must be performed in who grade ii meningiomas after simpson grade ii resection .
some authors have found statistical significance between radiotherapy and the recurrence rate , and they recommended irradiation , irrespective of the extend of resection2,19 ) . however , in another study3 ) in which 8 of 22 patients with atypical meningiomas received post - operative radiotherapy , local control was 87% at 5 and 10 years following gtr , and radiotherapy had no significant impact on local control or overall survival .
mccarthy et al.11 ) reported studies which included patients with grade ii meningiomas who underwent gross total resection , and failed to demonstrate a statistically significant change in local control or survival in patients receiving adjuvant radiotherapy .
a number of authors do not recommend radiotherapy for atypical meningiomas regarding the extent of surgical resection because the majority of patients with atypical meningiomas would ultimately experience local recurrence despite a course of conventional radiation treatment5,7 ) there are no randomized trials to support any opinion regarding the role of post - operative radiotherapy , and it is still debatable whether or not these patients should be carefully observed or treated pre - emptively . because of the rarity of who grade ii meningiomas and differences in the way who grade ii meningiomas are classified , the literature on the role of radiation in treating such patients are difficult to interpret .
this study had a limitation with respect to the small sample size . also , the data for our study were collected retrospectively , and thus a potential for bias may exist . the gold standard for evaluating
our treatment policy is a prospective randomized trial , but this approach is thought to be difficult due to the rarity of atypical meningiomas .
nevertheless , the fact that the surgical procedure was performed by one surgeon adds credibility to our study .
1 ) in who grade ii meningiomas , complete resection ( simpson grade i ) is the most important factor for preventing recurrence .
however , in the completely resected group , the effect of post - operative radiation therapy is uncertain in this study .
2 ) if the degree of resection is simpson grade ii , the recurrence rate is similar to the complete resection group , although post - operative radiotherapy is not performed .
it is questionable whether or not post - operative radiotherapy must be performed in who grade ii meningiomas after simpson grade ii resection .
3 ) regardless of post - operative radiotherapy , if the degree of resection is simpson grade iii or iv , the risk of recurrence is significantly high .
1 ) in who grade ii meningiomas , complete resection ( simpson grade i ) is the most important factor for preventing recurrence .
however , in the completely resected group , the effect of post - operative radiation therapy is uncertain in this study .
2 ) if the degree of resection is simpson grade ii , the recurrence rate is similar to the complete resection group , although post - operative radiotherapy is not performed .
it is questionable whether or not post - operative radiotherapy must be performed in who grade ii meningiomas after simpson grade ii resection .
3 ) regardless of post - operative radiotherapy , if the degree of resection is simpson grade iii or iv , the risk of recurrence is significantly high .
the extent of resection is the most powerful independent predictive factor for recurrence of who grade ii meningiomas . if complete resection was performed , the recurrence rate of who grade ii meningiomas was reduced to that of benign meningiomas , regardless of adjuvant treatment .
post - operative adjuvant radiotherapy was not a significant factor in this study , also it continued to be controversial according to previous reports .
however , because of several limitations of this study , re - estimation of the role of post - operative radiotherapy is required . | objectiveintracranial meningiomas are primarily benign tumors with a good prognosis .
although who grade ii meningiomas are rare ( 2 - 10% ) , who grade ii meningiomas have higher recurrence and mortality rates than benign .
we evaluated the patient recurrence rate and investigated the prognostic factors of who grade ii meningiomas.methodsbetween 1993 and 2005 , 55 patients were diagnosed with who grade ii meningiomas in our hospital . who grade ii meningiomas ( n=55 ) were compared with other who grades meningiomas ( i , n=373 ; and iii , n=20 ) .
the patients had a median age of 48.4 years ( range , 14 - 17 years ) , a male - to - female ratio of 26 : 29 , and a mean follow - up time of 45 months ( range , 3 - 175 months).resultsin who grade ii meningiomas , only the extent of resection was a significant prognostic factor .
post - operative radiotherapy had no significant influence on tumor recurrence ( p=0.053 ) .
the relative risk of recurrence was significantly higher in who grade ii meningiomas with incomplete resection ( 10/27 , rr=37% ) than in who grade ii meningiomas with complete resection ( 4/28 , rr=14% ) regardless of post - operative radiotherapy . in the incomplete resection group , simpson grade iii or iv had a significantly high risk of recurrence regardless of post - operative rt ( n=3 , rr=100% ) however , if the degree of resection was simpson grade ii , the recurrence rate was similar to the complete resection group even though post - operative rt was not performed.conclusioncomplete resection was the most powerful independent predictive factor of the recurrence rate in who grade ii meningiomas .
post - operative adjuvant rt was not a significant factor in this study . |
intensive monitoring of black hole x - ray binaries ( bhbs ) has established a set of characteristic outburst states classified by the x - ray luminosity , colour ( `` hardness '' ) , rms variability , and spectral shape ( e.g. @xcite , hereafter rm06 ) . at the highest observed luminosities , the spectrum is dominated by a steep ( photon index @xmath2 ) power law extending in some cases to mev energies @xcite .
this `` steep power law '' or `` high intermediate '' state is associated with quasi - periodic oscillations ( qpos ) .
the high - frequency ( @xmath3 ) qpos ( hfqpos ) are of particular interest , as their frequencies are comparable to the expected orbital frequency near the innermost stable circular orbit ( isco ) of a stellar mass black hole .
hfqpos have been observed in seven bhbs , with typical amplitudes @xmath4 . in some cases
twin frequencies appear with a 3:2 ratio ( e.g. , * ? ? ?
they are associated with the power law ( hard ) rather than the accretion disc ( soft ) spectral component ( rm06 ) .
observations of hfqpos are a promising means to measure black hole spin @xcite and probe strong gravity , provided that a model for their origin can be found .
many models have been proposed for hfqpos , e.g. oscillations in accretion discs @xcite or orbiting hotspots @xcite , but from these models it is difficult to determine why a 3:2 frequency ratio should be seen , why the qpos should be associated with the power law spectral component , and why they should appear only at high luminosity .
numerical mhd simulations of black hole accretion discs do not find significant power from orbiting hotspots @xcite .
on the other hand , localized vertical oscillation modes are observed in vertically stratified radiation mhd shearing box simulations @xcite .
the two strongest modes are the vertical epicyclic oscillation and lowest - order acoustic breathing mode . in a radiation - dominated medium
( with adiabatic index @xmath5 ) , the period ratio of these modes is @xmath6 , nearly identical to the observed 3:2 ratio of hfqpos in several sources .
this ratio is completely independent of the detailed vertical structure @xcite .
these vertical oscillations have also been observed in global mhd simulations @xcite , where they appear to be independently excited at each radius , so that their frequencies scale approximately as @xmath7 .
the modes will therefore blend together into broadband noise when averaging the emission over the disc , unless some mechanism exists which can filter the power from a narrow range in radius .
the origin of the steep power law spectrum observed in bhbs at near eddington luminosities is also poorly understood .
a hot , tenuous corona could compton scatter the bulk of the disc seed photons into a power law @xcite .
radiative transfer calculations from an mhd simulation have shown that steep power law spectra can be produced in this way if enough of the accreting material goes into the corona rather than the disc @xcite . however
, this scenario does not naturally explain the origin or properties of observed hfqpos .
we propose an alternative scenario for the steep power law state , where the accretion disc itself produces the entire x - ray spectrum .
we use a semi - analytic accretion disc model to calculate approximate spectra ( [ sec : spectral - calculation ] ) and hfqpo profiles ( [ sec : filt - high - freq ] ) , demonstrating that high quality oscillations are naturally associated with steep power law spectra , and that both only appear at high luminosities .
we give a qualitative example of measuring spin from hfqpo and spectral observations of gro j1655 - 40 in [ sec : parameter - space - spin ] , and discuss further implications and predictions of the model in
[ sec : discussion ] .
accretion disc spectra at luminosities comparable to eddington could naturally provide a filter for hfqpos , as long as sufficient radiation can be generated by the inner radii . at high luminosities ,
radiation - dominated discs are expected to become effectively optically thin .
global , general relativistic mhd simulations have found that the inner radii can still produce a significant amount of emission ( e.g. , * ? ? ?
@xcite showed that the combination of these factors can lead to a rapid increase in gas temperature in the inner radii , leading to a high energy power law spectral tail from the superposition of saturated wien spectra . at high luminosity , this power law tail becomes dominant , consistent with the observed steep power law spectra in bhbs where the hfqpos are seen ( figure [ spectra ] ) .
the gas temperature , and the peak energy of the resulting wien spectra , rise rapidly inwards .
therefore , the power law tail is naturally associated with a narrow range of radius .
this effect can explain the presence of sharp hfqpos ( @xmath8 ) in steep power law spectra and their association with high energy photons ( figure [ qpo ] ) .
we demonstrate the plausibility of this scenario for the steep power law state by estimating spectra and qpo power profiles from the semi - analytic thin accretion disc model of ( * ? ? ?
this model is a generalization of the standard thin disc model @xcite allowing for a non - zero stress and luminosity at the isco .
effective temperature profiles from the ak00 model are in reasonable agreement with current grmhd simulations @xcite .
the ak00 model only adds a single parameter to standard accretion disc models , @xmath9 , the increase in overall radiative efficiency relative to a standard accretion disc , and is therefore a simple way to capture the required physics .
however , we note that a more complicated slim disc model ( e.g. , * ? ? ?
* ) would provide a more realistic treatment of accretion physics at high luminosity , where advection is important and the disc is no longer thin .
the other model parameters are the @xcite viscosity parameter @xmath10 , the normalized accretion rate ( @xmath11 ) , and the black hole mass ( @xmath12 ) and spin ( @xmath13 ) . here
we fix @xmath14 and @xmath15 and vary the other parameters .
sample disc - integrated spectrum ( top ) and contributions from several annuli ( bottom ) .
many radii contribute to the spectral peak , while the rapid increase in gas temperature in the effectively optically thin annuli lead to well separated spectral peaks , whose sum leads to a steep power law tail .
the local spectra are saturated compton ( wien ) spectra , whose luminosities are significantly suppressed in comparison to blackbody spectra at the same temperature .
the parameters are @xmath16 , @xmath17 , and @xmath18 .
the resulting luminosity is @xmath19 . ]
synthetic qpo profiles from our sample disc model .
annuli spectra are assumed to contribute to the power at the local vertical epicyclic frequency , and are integrated over various bands in energy and then normalized . at low energies ,
many radii contribute , resulting in a broad flat profile .
a sharp qpo - like peak is produced at higher energies where a narrow range in radius dominates the total flux .
the quality factor , measured as @xmath20 for a gaussian profile , is @xmath21 , @xmath22 , @xmath23 for energy bands of @xmath24 , @xmath25 , and @xmath26 kev .
the model parameters are @xmath16 , @xmath17 , and @xmath18 . compare to the observed @xmath27 hz qpo in gro 1655 - 40 @xcite . ]
we use the ak00 surface density , effective temperature , and scale height profiles to calculate the gas temperature and spectrum from each disc annulus , spaced evenly in @xmath28 .
we use a one zone model ( ignoring vertical structure ) , and assume that radiation pressure dominates throughout the disc .
the local spectrum is calculated using the approximate solutions for comptonised bremsstrahlung with @xmath29 described in @xcite 7.6 .
the temperature and spectrum are calculated iteratively by matching the integrated local spectrum to the flux required by the model at that radius : @xmath30 , where @xmath31 is the intensity .
( we neglect relativistic factors in this spectral calculation , though they are included in the disc structure model . ) in optically thick annuli at relatively large radius , the intensity is a modified blackbody spectrum with a colour - correction factor @xmath32 .
effectively optically thin annuli instead produce a wien spectrum with a total flux of @xmath33 , where @xmath34 is the bremsstrahlung emissivity , @xmath35 is the disc scale height , and @xmath36 is the amplification factor of the local bremsstrahlung emission by inverse compton scattering .
the wien intensity is much smaller than the blackbody intensity at the same temperature in the inner radii where absorption is inefficient . in order to maintain the required effective temperature
, the gas must become extremely hot , reaching gas temperatures a factor @xmath37 larger than the effective temperature near the isco for @xmath38 ( figure [ tautemp ] ) .
this does not occur in nt73 discs , where the effective temperature artificially drops to zero at the isco .
sample spectra from the full disc and several local area - weighted annuli are shown in figure [ spectra ] .
the rapid increase in gas temperature in the inner radii leads to a superposition of wien spectra with higher and higher energy peaks .
although their normalizations also increase moving inwards , fewer annuli contribute to the emission , creating a power law tail with a photon index of @xmath39 , in agreement with observed steep power law spectra ( rm06 ) . on the steep power law tail portion of the spectrum ,
the flux at a given energy is produced by a narrow range in radius .
we roughly estimate the hfqpo component of the power spectrum of our model by assuming that the local qpo flux amplitude is proportional to the total local x - ray flux .
a linear rms - flux relation is seen locally in radiation mhd simulations and is also seen observationally @xcite .
we further assume that the qpo amplitude is proportional to the rms noise . using this approximation ,
the qpo profile is calculated by integrating the flux in each annulus over a desired energy band , and dividing by the total flux in that energy band .
each annulus contributes to the qpo amplitude at a different frequency , which we take to be the vertical epicyclic frequency at that radius for a chosen black hole mass and spin .
the profile is then normalized by the total flux in the band , and squared to convert to power .
a sample qpo profile is shown in figure [ qpo ] corresponding to the spectrum in figure [ spectra ] .
the parameters are chosen to reproduce the observed @xmath40 oscillation in gro 1655 - 40 at @xmath41 hz ( cf .
rm06 figure 11 ) .
when the flux of a chosen energy band is dominated by optically thick annuli , a wide range of radii contribute and the profile is flat with no qpo ( e.g. , @xmath42 kev ) . when the flux in the energy band is dominated by optically thin annuli , qpos naturally emerge from the narrow range in radius corresponding to the band .
the qpo profiles are narrower ( higher @xmath43 ) when integrated over smaller energy bands .
the q values found are @xmath44 for hard energy bands
( @xmath45 kev ) depending on the model parameters and energy band , consistent with observed hfqpos .
measures of optical depth ( top ) and temperature ( bottom ) as functions of radius for the model in figures [ spectra ] and [ qpo ] .
the gas temperature becomes significantly larger than the effective temperature in the inner radii where the absorption opacity is small.,title="fig : " ] + measures of optical depth ( top ) and temperature ( bottom ) as functions of radius for the model in figures [ spectra ] and [ qpo ] .
the gas temperature becomes significantly larger than the effective temperature in the inner radii where the absorption opacity is small.,title="fig : " ] regions of model parameter space in qpo frequency ( top ) and luminosity ( bottom ) vs. black hole spin .
the different shaded regions correspond to i ) spectra with @xmath46 and qpos with @xmath47 integrated over 6 - 30 kev ( blue ) , ii ) the subset with qpo frequencies @xmath48 hz ( orange ) , and iii ) the subset where the qpo frequency is stable over factors @xmath45 in luminosity and where @xmath49 as seen in gro j1655 - 40 ( rm06 , red ) .
we use these constraints to qualitatively estimate a spin of @xmath50 for gro j1655 - 40.,title="fig : " ] + regions of model parameter space in qpo frequency ( top ) and luminosity ( bottom ) vs. black hole spin .
the different shaded regions correspond to i ) spectra with @xmath46 and qpos with @xmath47 integrated over 6 - 30 kev ( blue ) , ii ) the subset with qpo frequencies @xmath48 hz ( orange ) , and iii ) the subset where the qpo frequency is stable over factors @xmath45 in luminosity and where @xmath49 as seen in gro j1655 - 40 ( rm06 , red ) .
we use these constraints to qualitatively estimate a spin of @xmath50 for gro j1655 - 40.,title="fig : " ] figure [ gro ] shows the portion of parameter space where the disc model produces power law spectra with @xmath51 along with qpos ( @xmath47 ) .
such models are possible at all black hole spin values over a range of luminosity , producing a wide range of hfqpo frequencies at each spin .
power law spectra require higher luminosities for small black hole spin , because the effective optical depth is higher at fixed luminosity .
the qpo frequency increases with spin along with the underlying vertical epicyclic mode frequency .
the maximum qpo frequency at each spin is the mode frequency at the isco , the model inner boundary .
physically , we expect that standing vertical oscillations should not exist inside that radius , although exactly where the modes are present in radius should be investigated with future simulations
. a large range of qpo frequencies are possible at each value of black hole spin .
however , it is still possible to have relatively stationary qpos ( @xmath52 changes ) over ranges of factors @xmath53 in luminosity as observed ( e.g. , * ? ? ?
* ) , as long as the luminosity changes derive from variations in the accretion rate .
changing the luminosity by changing @xmath9 instead leads to large changes in the spectral shape and qpo frequency with luminosity , inconsistent with observations .
the favored value is @xmath54 , or equivalently a smooth effective temperature profile with radius ( figure [ tautemp ] ) .
the radius where the qpo emerges is @xmath55 , and measuring black hole spin from observed hfqpos requires measuring this radius using spectral information .
we demonstrate this procedure using the x - ray binary gro j1655 - 40 as an example .
the measured @xmath56 qpo constrains the parameter space , but solutions still exist at all values of black hole spin .
the stability of hfqpos with factor of few changes in luminosity limits the spin to @xmath57 , and the observed photon indices @xmath58 ( rm06 ) would lead to an estimate @xmath50 .
this is comparable to the spin measured using the thermal continuum method ( @xmath59 , @xcite ) , but lower than that inferred from fluorescent iron line measurements ( @xmath60 , @xcite ) and higher than a recent estimate from the relativistic precession qpo model ( @xmath61 * ? ? ?
this is a qualitative example .
quantitatively , the spin constraint is subject to systematic uncertainties from our choice of disc model ( surface density and effective temperature profiles ) and approximations used in the spectral calculation .
we have proposed a novel model for steep power law state spectra and hfqpos in bhbs .
we propose that hfqpos are due to local vertical epicyclic and acoustic breathing modes , whose frequency ratio is @xmath62 in radiation pressure dominated media , independent of vertical structure .
a standard disc becomes effectively optically thin well outside the isco at high luminosity , and these annuli must become extremely hot to produce significant luminosities .
we have shown that saturated wien spectra from these annuli can lead to the observed steep power law spectrum , and simultaneously provide a filter to associate the observed x - ray energy band with a narrow range in radius , and hence a narrow range in hfqpo frequency .
this model can therefore simultaneously explain the steep power law state spectra and hfqpos within the context of standard thin accretion disc theory .
we have given an example for how to use the model along with observed hfqpos and spectral properties to estimate black hole spin , qualitatively inferring @xmath50 for gro j1655 - 40 .
for simplicity , we have used the ak00 model , which is based on standard thin disc accretion theory but can explain luminosity profiles from numerical mhd simulations of black hole accretion discs @xcite .
however , it is not clear whether standard thin disc accretion theory can be applied when the disc is radiation - dominated .
recent radiation mhd simulations have found that the disc may be thermally unstable ( jiang , stone & davis 2013 , submitted ) , and the non - linear saturation of the instability has not yet been studied .
global simulations of the entire disc will be needed to determine its structure , but it may still be that it resembles that of a standard thin disc .
observationally , there is little evidence for the thermal instability in bhbs , except perhaps in some sources reaching very high luminosities @xcite .
the important assumptions of our model are that the surface density decreases with decreasing radius , so that at high luminosities the inner radii become effectively optically thin , and that these radii have substantial luminosities ( high effective temperatures ) .
we have used approximate analytic solutions for the emergent spectrum and ignored the vertical disc structure .
the results qualitatively agree with more accurate radiative transfer calculations @xcite . the gas temperature should continue to increase inside the isco , and including these annuli would likely extend the spectrum to higher energies ( @xmath63 ) .
relativistic effects , including doppler beaming , are also likely to modify the spectrum further from what is assumed here , and a proper ray tracing calculation ( e.g. @xcite ) of the model spectrum and hfqpos will be necessary to make more robust predictions . extending the power law emission to photon energies beyond an mev @xcite may also require a nonthermal electron population .
we have also ignored the effects of radiative advection @xcite , which become important at the high luminosities considered .
@xcite further showed that in some cases bhb spectra become softer at high luminosities , implying that the disc is truncated outside of the isco , unlike what we have assumed here .
the present treatment is sufficient to demonstrate the promise of the model , and we intend to address many of these issues in the future .
the amplitudes of simulated modes relative to the noise is uncertain , but we can estimate the local mode amplitudes required to explain the observed hfqpos using our model . for the acoustic breathing mode ( proposed to be @xmath64 ) , the flux perturbation is @xmath65 , where @xmath66 is the velocity perturbation and @xmath67 is the sound speed . for the observed qpo amplitudes of order a per cent , a small velocity perturbation should suffice to excite the mode to observable levels .
the vertical epicyclic mode is a displacement of the fluid in the vertical direction , and does not directly lead to a flux perturbation . in order to produce an observable qpo ,
this motion must be detectable , e.g. , from doppler beaming .
the flux perturbation for doppler beaming would be @xmath68 , where @xmath69 is the vertical displacement . at small radius , where the scale height is large ( @xmath70 ) , this is a small displacement .
observationally , the hfqpos forming the stable 3:2 ratio pair do not always appear simultaneously
. this would not be surprising if they correspond to the vertical epicyclic and acoustic breathing modes , given their distinct excitation physics .
the vertical epicyclic mode requires a vertically asymmetric momentum ejection to displace the local disc centre of mass .
the observed trend that the vertical epicyclic mode is seen at higher power law luminosities @xcite is interesting since those observations may be closer in time to the observed transient jet ejections , which could excite vertical disc oscillations . in our model ,
the disc is optically thick to electron scattering at all radii ( @xmath71 , figure [ tautemp ] ) , and the photon diffusion time out from the midplane is a factor of @xmath72 longer than the mode period .
however , in current radiation mhd simulations the breathing mode amplitude grows linearly with height up to the photosphere , where the diffusion time becomes short , allowing the mode to produce flux variations at each radius .
we have assumed that the modes are excited independently at each radius , as found in the global simulations of @xcite .
recent measurements find stable phase lags over the range of qpo frequencies @xcite , perhaps suggesting at least some radial coherence for the modes .
in addition to our spectral filtering mechanism , trapping the modes in the radial direction would allow for higher quality factors and more stable qpo frequencies than found here .
for example , localised rings of pressure and density , such as might form in the development of a radiation pressure driven viscous " instability @xcite , could create coherent axisymmetric oscillations @xcite .
the proposed model makes several predictions testable with current archival data and future x - ray missions .
first , we predict that restricting the energy band used to measure the power spectrum should lead to higher quality hfqpos , since this is effectively selecting for a narrower set of radii in the accretion disc .
in addition , the measured hfqpo frequencies are not necessarily expected to match the mode frequency at the isco or at any particular radius .
small variations in the radius where the qpo profile peaks should lead to frequency changes of @xmath73 as the luminosity varies by factors of several , and shifts of similar magnitudes are reported by @xcite .
we further predict that the qpo frequency should decrease with increasing luminosity , as disc temperatures corresponding to a particular photon energy band move to larger radius .
detections of hfqpos in hard x - rays may also find shifts of the hfqpo to higher frequency .
the vertical epicyclic mode and the lowest order acoustic breathing mode are the most pronounced in current local radiation mhd simulations of black hole accretion discs , but several other higher order modes are present as well .
these could lead to additional hfqpos at higher frequency .
although we have assumed these two modes , the proposed steep power law spectrum is a general mechanism for filtering modes from a narrow range of radii , and could apply to other models for disc oscillations or orbiting inhomogeneities .
further , if hfqpos are the result of narrow ranges in radius producing certain energy ranges of steep power law spectra , then this should have consequences for the broadband noise as well .
for example , the power spectrum slope or break frequency may depend on the chosen x - ray energy band .
the b type low - frequency qpos are correlated with hfqpos in the steep power law state @xcite , but are left unexplained by our model .
future studies aiming to explain the origin of these features may be guided by the framework for the steep power law spectrum and hfqpos presented here .
we thank d. altamirano , s. davis , c. done , j. krolik , and e. quataert for stimulating discussions related to this work , as well as the referee , o. straub , for useful comments .
this work was partially supported by the university of california high - performance astrocomputing center . | we propose a new model of the steep power law state of luminous black hole x - ray binaries .
the model uses the fact that at high luminosities , the inner radii of radiation pressure dominated accretion discs are expected to i ) become effectively optically thin and ii ) produce significant luminosities .
the gas temperature therefore rises sharply inwards , producing local saturated compton spectra with rapidly increasing peak energy . these spectra sum together to form a steep power law tail to the spectrum .
a given photon energy on this tail corresponds to a narrow range in radius , so that local vertical oscillations of the disc naturally produce high quality high - frequency quasi - periodic oscillations ( hfqpos ) in the hard x - ray band .
the two lowest order modes have a robust frequency ratio of @xmath0 .
this model explains the appearance of steep power law spectra and hfqpos at high luminosity , the 3:2 hfqpo frequency ratios , and their association with the power law spectral component .
we predict an increase in qpo quality factor when the power spectrum is restricted to a narrower photon energy band , and an increase in hfqpo frequency at higher x - ray energies or lower luminosities .
future x - ray telescopes could detect additional hfqpos from higher order modes .
we demonstrate how this model could be used to measure black hole spin from hfqpos , and qualitatively estimate the spin of gro j1655 - 40 as @xmath1 .
[ firstpage ] accretion , accretion discs black hole physics x - rays : binaries relativity |
idiopathic cluster of differentiation 4 ( cd4 + ) t - cell lymphocytopenia ( icl ) is a rare non human immunodeficiency virus ( hiv)-related syndrome with unclear natural history and prognosis that was first reported and defined in 1992 .
icl has been observed in patients after the onset of an opportunistic infection without known immunosuppression .
a 20-year - old hispanic male patient without significant past medical history presented with progressive shortness of breath and cough for 3 weeks .
the hiv rapid screening test as well as the sputum acid - fast bacilli test were both positive .
the cd4 count was noticed to be low . however , the hiv western blot test was negative , and the hiv viral load was within normal limit .
follow - up after 8 weeks revealed a persistent low cd4 + count , and the repeated hiv tests were negative .
the clinical features of icl range from an asymptomatic condition to life - threatening complications that imitate the clinical course of hiv - infected patients . the differential diagnosis in adults comprises primarily hiv infection and other diseases or drug side effects .
icl is very rare and should be considered in the absence of any defined immunodeficiency or therapy associated with depressed levels of cd4 + t - cells .
early detection and recognition of the disease allow purposeful and systemic treatment approach and screening for the affected patients .
idiopathic cluster of differentiation 4 ( cd4)+ lymphocytopenia ( icl ) was first defined in 1992 by the us centers for disease control and prevention ( cdc)1 as : a documented absolute cd4 t - lymphocyte count of < 300 cells / mm or < 20% of total t - cells on two separate time points at least six weeks apart without evidence of infection on hiv-1 or hiv-2 testing , and without immunodeficiency or therapy related to decrease of cd4 t - cells
the cdc definition allows the inclusion of patients with pan - lymphocytopenia and normal cd4:cd8 ratio .
icl is a very rare syndrome with an unknown etiology , not caused by human immunodeficiency virus ( hiv)-1 , hiv-2 , human t - lymphotropic virus type i , or human t - lymphotropic virus type ii , and not appearing to be caused by any transmissible agent.2 sporadic icl cases are reported from all over the world .
icl has been observed in patients after the onset of opportunistic infection without known immunocompromisation or immunosuppression .
we are reporting a case of a young hispanic male who presented with progressive dry cough and shortness of breath , which turned out to be a case of icl with pulmonary tuberculosis .
a 20-year - old hispanic male with no past medical history presented to our institution complaining of generalized weakness for 4 weeks , progressive cough with yellowish sputum , as well as persistent shortness of breath for 3 weeks , and intermittent fever and chills for 35 days prior to admission .
he had lived with his girlfriend for 2 years and stated to be monogamous over this period .
he was born in texas and had not traveled outside the us for the last 12 years .
physical examination revealed a cachectic and tachypneic patient in no acute distress with bilateral diffuse crackles and rhonchi .
computed tomography of the chest ( figure 1 ) showed diffuse tree - in - bud nodularity , bronchiectasis , and thick - walled cavities in the upper lobes and moderate right simple pleural effusion .
the acid - fast bacilli sputum test was positive , and the patient was started on combination treatment for tuberculosis .
the cd4 + and cd8 counts were low ( 124 and 185 , respectively ) with a low cd4:cd8 ratio of 0.7 .
further workup including immunoglobulin a , immunoglobulin g , and immunoglobulin m levels , urine protein electrophoresis , and serum protein electrophoresis was unremarkable .
the pleural fluid cytology revealed atypical lymphocytes consistent with the established diagnosis of pulmonary tuberculosis .
he was taking his medication to treat tuberculosis and had regular health care follow - up .
he was found to be completely asymptomatic with a cd4 + count of 188 cells / mm .
after finishing his treatment for tuberculosis , he was evaluated in clinic , had a cd4 + count of 212 cells / mm , and remained asymptomatic .
with the increased incidence of acquired immunodeficiency syndrome and the related risk of opportunistic infections , the public attention was higher to investigate more about possible other associations .
the cd4 + t - lymphocyte is reduced in hiv infection as well as in icl , and the opportunistic infections that affect patients with icl are similar to those in hiv - positive patients with low cd4 + t - lymphocyte counts.3 in our patient , the initial presentation with a false - positive hiv test might be attributed to the existing infection with tuberculosis .
several reports described this association over the last 20 years.4,5 however , hiv screening must be considered in the presence of tuberculosis or other opportunistic infections in a low - risk patient , as in our case . in 1993 ,
the cdc reviewed 23,179 cases in its acquired immunodeficiency syndrome reporting registry and discovered 47 cases that met the diagnostic criteria for icl .
there was no detectable bias of the age at diagnosis or in the sex of the patients ( 29 males and 18 females).6 no cases of icl were identified among the 2,028 screened blood donors.7 the etiology of icl is unknown and not clearly understood .
a few observational studies have suggested the role of various immune defects and their association to cd4 + lymphocyte function .
apoptosis of cd4 + lymphocytes or the activation of cd4 + due to an unidentified pathogen stimulation could be factors that result in the development of icl.8,9 genetic predisposition may also be involved .
however , very few familial cases have been reported who presented with icl.10,11 the human leukocyte antigen - d ( hla - d ) related cd4 + cells were discovered to be higher in patients with icl compared to the control group.8 icl - affected patients tend to have a progressive decline of cd4 + lymphocyte cell count ; whereas , hiv - infected patients have a slower decline of cd4 + lymphocyte cell count .
several reports have demonstrated the expansion of t - cells as a result of t - cell redistribution or concomitant infection.12,13 a differential diagnosis for cd4 + lymphocytopenia includes : autoimmune disorders ; malignancy ; infectious causes ; medication - induced ; or other primary immunodeficiency diseases or syndromes.1418 the hiv infection is the most common differential diagnosis of low cd4 + lymphocytopenia .
bacterial , fungal , parasitic , and viral infections can depress the cd4 + count ; however , the cd4:cd8 ratio remains unaffected.19,20
cryptococcus is the most common cause of opportunistic infection in icl , followed by mycobacterium and herpes zoster virus .
kaposi s sarcoma in icl patients is associated with a severe reduction of cd4 + counts in combination with hypogammaglobulinemia or steroid therapy.21,22 hematological malignancies have also been proposed to cause cd4 + lymphocytopenia .
ayoub et al described the association between non - hodgkin s lymphoma ( mucosa - associated lymphatic tissue , large cell lymphoma , and burkitt s lymphoma ) with lymphocytopenia and a normal cd4:cd8 ratio.23 patients with icl may have a predisposition for developing cervical neoplasias , depending on the human papillomavirus type .
according to several studies , icl was present in patients with various autoimmune disorders.2426 the risk of opportunistic infections in autoimmune patients with cd4 + lymphocytopenia is not known .
glck et al demonstrated in a cross - sectional study of 97 patients with autoimmune disease that the effect of immunosuppressive therapy is associated with higher infection rate and decrease of cd4 + t - lymphocyte cell counts.27 cyclophosphamide caused a more profound decrease in lymphocytes and cd4 + cells ( < 250 cells / ml ) compared to methotrexate or azathioprine .
a few reports have demonstrated an improved cd4 + t - lymphocyte cell count with antimycobacterial treatment in icl patients with mycobacterial infections.28 icl seems to persist despite treatment and remission in those with an autoimmune disorder .
pneumococcal prophylaxis is recommended when the cd4 + t - cell count is < 200 cells / ul.29 lifetime prophylaxis is indicated for cryptococcosis and relapsing herpes infection .
prophylaxis and treatment for hepatitis b and hepatitis c infection should be similar to the established recommendations for patients with hiv infection .
clinical features of icl range from being asymptomatic to life - threatening complications that are similar to the clinical course of patients with hiv infection .
the simultaneous occurrence of opportunistic infections often permits the detection of new onset of icl . established guidelines for the treatment of idiopathic and non - hiv - related secondary cd4 + lymphocytopenia are not available , and current recommendations are controversial .
icl should be considered in the absence of any immunodeficiency disorder or immunosuppressive therapy associated with decreased cd4 + t - lymphocyte cell count .
early consideration and recognition of the disease can allow for a more purposeful and systemic approach to screening and therapy . | introductionidiopathic cluster of differentiation 4 ( cd4 + ) t - cell lymphocytopenia ( icl ) is a rare non human immunodeficiency virus ( hiv)-related syndrome with unclear natural history and prognosis that was first reported and defined in 1992 .
icl has been observed in patients after the onset of an opportunistic infection without known immunosuppression.case presentationa 20-year - old hispanic male patient without significant past medical history presented with progressive shortness of breath and cough for 3 weeks .
chest computed tomography showed bilateral cavitary lesions in the upper lung lobes .
the hiv rapid screening test as well as the sputum acid - fast bacilli test were both positive .
the patient was started on antituberculosis therapy .
the cd4 count was noticed to be low . however , the hiv western blot test was negative , and the hiv viral load was within normal limit .
further radiologic studies , hemato - oncologic , and autoimmune workups were normal .
the patient was discharged on the treatment for tuberculosis .
follow - up after 8 weeks revealed a persistent low cd4 + count , and the repeated hiv tests were negative.conclusionthe clinical features of icl range from an asymptomatic condition to life - threatening complications that imitate the clinical course of hiv - infected patients .
the differential diagnosis in adults comprises primarily hiv infection and other diseases or drug side effects .
icl is very rare and should be considered in the absence of any defined immunodeficiency or therapy associated with depressed levels of cd4 + t - cells .
early detection and recognition of the disease allow purposeful and systemic treatment approach and screening for the affected patients . |
one of the fundamental questions of solar system formation is the origin of planetary spins .
the spin axes of three of the four giant planets in our solar system are tilted significantly , with the present values of the obliquities ( the angle between the spin axis and the orbit normal ) of jupiter , saturn , uranus , and neptune equal to @xmath0 , @xmath1 , @xmath2 , and @xmath3 , respectively .
@xcite has recently proposed a unified mechanism for the origin of the obliquities of the giant planets .
the starting point of brunini s model is the so - called nice model @xcite for the establishment of the orbital architecture of the giant planets . in the nice model ,
the outer solar system was initially compact , with jupiter and saturn closer than their mutual 2:1 mean - motion resonance and all of the giant planets within @xmath4 of the sun .
the scattering of planetesimals initially in a disk starting just beyond the orbits of the planets caused jupiter to migrate inward and saturn , uranus , and neptune outward .
when jupiter and saturn crossed the 2:1 mean - motion resonance , their orbital eccentricities were excited and the orbits of uranus and neptune were destabilized .
a phase of close encounters among the giant planets followed , and uranus and neptune were scattered outward .
the orbital eccentricities and inclinations of the giant planets were eventually damped to their present values by the interactions with planetesimals .
@xcite has performed numerical simulations of the nice model that follow the evolution of the planetary spin axes .
he found that large obliquities are generated during the encounter phase and that the final obliquities are similar to the present values , including the @xmath2 obliquity of uranus .
@xcite has subsequently retracted his paper on the basis that simulations performed with another numerical code do not reproduce the previous results and show changes in the obliquities of only a few degrees in most runs .
however , he did not provide any physical explanation as to why the later numerical results are more likely to be correct .
given the wide publicity of the first results , we thought it important to show in this paper a simple analytic argument ( section 2 ) that explains why significant obliquities of the outer planets can not result from close encounters between these planets in the nice model .
the analytic argument is verified by numerical simulations ( section 3 ) .
we note that a summary of our results was presented by @xcite prior to the retraction by @xcite .
while our focus is on the nice model , our analysis of the obliquity changes in encounters can also be adapted to any scenario involving close encounters among the planets , such as the scenario proposed by ( * ? ? ?
* see also @xcite ) , in which several ice giants were formed in the outer solar system and all but two were ejected by encounters .
let us consider the change in the spin direction of a planet of mass @xmath5 , radius @xmath6 , and spin frequency @xmath7 , due to an encounter with a perturbing planet of mass @xmath8 .
if we assume principle axis rotation , the spin angular momentum of the planet is @xmath9 and the torque from the perturber at a distance @xmath10 in the direction @xmath11 is @xmath12 where @xmath13 is the unit vector of the spin direction , @xmath14 is the moment of inertia of the planet normalized to @xmath15 , and @xmath16 is the quadrupole coefficient of the planet .
the torque from the planet s oblate figure on a satellite locks the satellite to the planet s equator plane if the nodal precession period of the satellite is short compared to the timescale on which the spin direction of the planet is changed @xcite . in the above equations , @xmath17 is the orbital angular momentum ( normalized to @xmath18 ) of the satellites whose orbits are coupled to the planet s equator , and @xmath19 is the ratio of the torque from the perturber on the satellites to that directly exerted on the planet ( see @xcite for explicit definitions of @xmath17 and @xmath20 ) . from @xmath21 , the rate of change of the spin direction is @xmath22 where @xmath23 is the mass of the sun and @xmath24 is the precession constant of the planet ( plus its satellites ) at the _ current _ orbital semimajor axis , @xmath25 , of the planet .
because the torque decreases rapidly with the distance @xmath10 , we expect the total change in the spin direction in an encounter , @xmath26 , to be roughly equal to the rate of change at closest approach , @xmath27 , times the duration of closest approach , @xmath28 : @xmath29 where @xmath30 and @xmath31 are , respectively , the relative separation and speed at closest approach and the proportionality constant is a function of the encounter geometry .
a more accurate expression for @xmath32 can be obtained by neglecting solar gravity and using the two - body approximation during the encounter .
then @xmath33 where @xmath34(@xmath35 ) and @xmath36 are , respectively , the eccentricity and true anomaly of the relative orbit . in the coordinate system where the relative orbit is in the @xmath37-@xmath38 plane and
the closest approach is in the @xmath37 direction , the integration in eq .
( [ deltas ] ) yields @xmath39 \sin 2\theta \sin\phi { \mbox{\boldmath $ \hat x$}}\nonumber \\ & & \qquad -\left[\arccos(-1/e ) + { e \over 3 } \left(4 - 1/e^2\right ) \left(1 - 1/e^2\right)^{1/2}\right ] \sin 2\theta \cos\phi { \mbox{\boldmath $ \hat y$}}\nonumber \\ & & \qquad + { 2 e \over 3 } \left(1 - 1/e^2\right)^{3/2 } \sin^2\theta \sin2\phi { \mbox{\boldmath $ \hat z$}}\bigg\ } , \end{aligned}\ ] ] where @xmath40 and @xmath41 are the spherical coordinate angles specifying the orientation of the spin axis in the @xmath42 system : @xmath43
. contour plots of the magnitude , @xmath26 , as a function of @xmath40 and @xmath41 show that @xmath26 reaches equal maximum values at four points with @xmath44 or @xmath45 and @xmath46 or @xmath47 for any @xmath48 . for @xmath49 ( i.e. , parabolic encounter ) ,
@xmath50 , which is independent of @xmath41 and maximum at @xmath44 or @xmath45 .
the plot of the maximum @xmath26 for a given @xmath34 as a function of @xmath34 shows that it decreases monotonically with increasing @xmath34 .
thus @xmath26 , as a function of @xmath34 , @xmath40 , and @xmath41 , is maximum for @xmath49 and @xmath44 or @xmath45 : @xmath51 since uranus has the largest current obliquity and the largest changes in its spin direction come from encounters with saturn , we consider first the change in the spin direction of uranus due to an encounter with saturn . as we shall see in figs .
[ fig1 ] and [ fig2 ] , saturn s orbit ( of semimajor axis @xmath52 ) remains nearly circular , and an encounter between saturn and uranus must have uranus on an eccentric orbit ( of eccentricity @xmath53 ) , with uranus usually near its perihelion .
thus the relative encounter speed at large separation is @xmath54 \la 0.22 ( g m_0/a_{\rm s})^{1/2}$ ] if @xmath55 .
since the encounter phase occurs long after the formation of the regular satellites in the nice model , the regular satellite systems must survive the encounter , and a reasonable lower limit to the separation @xmath30 at closest approach is the semimajor axis @xmath56 of the orbit of titan around saturn . for @xmath57 , @xmath58 ( where @xmath59 and @xmath60 are the masses of saturn and uranus , respectively ) , and @xmath61^{1/2 } \approx [ 2 g ( m_{\rm s } + m_{\rm u})/r_p]^{1/2}$ ] .
so the maximum change in the spin direction of uranus from an encounter with saturn is @xmath62 if we adopt @xmath63 from @xcite . for the same encounter between uranus and saturn , the maximum change in the spin direction of saturn
is @xmath64 if @xmath65 @xcite .
if we also adopt @xmath66 from @xcite , the changes from an encounter between neptune and saturn are nearly identical to those from an encounter between uranus and saturn , with @xmath67 and @xmath68 , because uranus and neptune have similar masses and @xmath69 ( see eq .
( [ deltasmax ] ) ) . for an encounter between uranus and neptune , @xmath70 .
we do not consider encounters with jupiter , since such encounters usually result in systems that do not resemble the solar system by , e.g. , ejecting the planet encountering jupiter @xcite .
the precession constants adopted above include the contributions from the satellites of the planets . in the case of uranus ,
the contributions are mainly from titania and oberon
. however , the nodal precession periods of titania and oberon ( @xmath71 due to the oblateness of uranus alone and @xmath72 with the inclusion of the secular interactions among the satellites ; @xcite ) are much longer than the encounter timescale with either saturn ( @xmath73days for @xmath74 ) or neptune ( @xmath75day for @xmath76 ) , and their orbits would not be able to follow the equator of uranus during the encounter @xcite .
this would reduce @xmath77 and hence the already small maximum change in the spin direction of uranus by a factor of @xmath78 .
similarly , without the contributions from the satellites to the precession constants , the maximum changes in the spin directions of neptune and saturn are reduced by a factor of @xmath79 and @xmath80 , respectively .
then the maximum change in the spin direction is @xmath81 for any pair - wise encounter among saturn , uranus , and neptune , even if we consider an extremely close encounter with @xmath30 equal to twice the sum of the planetary radii , which the regular satellite systems are unlikely to survive .
we have just shown that the change in the spin direction in _ inertial space _ during an encounter between the planets is very small .
thus any change in the obliquity ( which is defined as the angle between the spin axis and the orbit normal ) must be due to a change in the orbital inclination . as we shall see in , e.g. , figs .
[ fig1 ] and [ fig2 ] , the orbital inclinations of the ice giants can reach maximum values of @xmath82@xmath83 during the encounter phase .
however , because the timescale on which the inclination is changed by encounters and damped by planetesimals ( @xmath84 ) is much less than the precession period of the spin axis about the orbit normal due to solar torque ( @xmath85 for uranus ) , there is not enough time for the spin axis to precess much due to solar torque , and the spin axis does not stray far from its initial position nearly perpendicular to the initial orbital planes of the planets .
therefore , we expect the obliquities to return to small values as the inclinations are damped to their present values .
to verify the analytic argument in section 2 and to eliminate the possibility of unexpected secular spin - orbit effects , we have performed numerical simulations of the sun and the four giant planets using the symplectic @xmath86-body code symba @xcite , which we have modified to include spin evolution . for the orbital evolution ,
we ignore the negligible effects of the oblateness of the planets , and we use imposed migration and damping of eccentricity and inclination to model the effects of the planetesimals . @xcite
have described how symba can be modified to include forced migration and damping of eccentricity and inclination .
the unit vector @xmath87 of the spin direction of planet @xmath88 is evolved according to @xmath89 where the symbols are as in eq .
( [ dsdt ] ) , but with the subscript 0 for the sun and @xmath90 for the planets . in eq .
( [ dskdt ] ) , the first term is due to the torque from the sun and the second term is due to the torques from the other planets . the recursively subdivided time step used by symba to handle close encounters between the planets is also implemented for the spin evolution due to the planetary torques . in the appendix
, we describe in more details how symba is modified to include spin evolution and the tests that were performed .
we present the results from 4 series of runs , each with 30 simulations .
the simulations were performed with a time step of @xmath91 . for the precession constants at the current orbital semimajor axes , we adopt @xmath92 for jupiter , @xmath93 for saturn , @xmath94 for the initially inner ice giant , and @xmath95 for the initially outer ice giant .
these values include the contributions from the satellites @xcite .
although the inner and outer ice giants can switch positions ( see , e.g. , fig .
[ fig1 ] ) , the fact that we adopt the parameters of uranus ( neptune ) for the initially inner ( outer ) ice giant is not important , because uranus and neptune have similar masses and @xmath69 .
the four series of runs have the following initial conditions in common : the orbital eccentricities are @xmath96 ; both the orbit normals and the spin axes are tilted by @xmath96 radians ( or @xmath97 ) from the @xmath98-axis of the inertial frame ; the mean anomalies , the arguments of perihelion , and the longitudes of the ascending nodes on the @xmath37-@xmath38 plane of both the orbits and the equators are random variables . in series i ,
the initial orbital semimajor axes and the imposed migration and damping of eccentricity and inclination are similar to those adopted by @xcite .
the initial semimajor axis of jupiter is @xmath99 .
the initial semimajor axis of saturn is varied in the range @xmath100@xmath101 , whereas those of the ice giants are varied in the ranges @xmath102@xmath103 and @xmath104@xmath105 , while keeping the initial orbital separation of the ice giants larger than @xmath106 .
the imposed migration rate is @xmath107 where @xmath108 is the difference between the current semimajor axis , @xmath109 , and the initial semimajor axis .
the migration timescale @xmath110 is varied between @xmath111 and @xmath112 , and the total time span of a simulation is @xmath113 .
the imposed eccentricity and inclination damping rates are @xmath114 respectively , with @xmath115 .
the eccentricity and inclination dampings are applied only if the orbital distance of a planet is between just outside the initial orbit of the outer ice giant and @xmath116 .
series ii is similar to series i , but with @xmath117 .
series iii and iv have initial orbital semimajor axes closer to those adopted by @xcite and use a different prescription for migration and damping .
the initial @xmath99 , and the initial semimajor axes of saturn and the inner and outer ice giants are varied in the ranges @xmath118@xmath119 , @xmath120@xmath121 , and @xmath122@xmath123 , respectively , with the ice giants at least @xmath106 apart . the main difference from series
i and ii is that the semimajor axis of the inner ice giant is about @xmath124 larger .
for the imposed migration , we use eq .
( [ dakdt ] ) for jupiter and saturn and @xmath125 \label{dakdtice}\ ] ] for the ice giants . with the inner ice giant further from saturn initially ,
the migration rate in eq .
( [ dakdtice ] ) ensures that the ice giants do not migrate too far by the time of the jupiter - saturn 2:1 resonance crossing , as seen in the simulations of @xcite .
for all planets , the damping rates are @xmath126 and they are applied at all times .
this form of damping has been used to model planet - disk interactions ( e.g. , @xcite ) , and it has the reasonable property of tying the damping rates to the migration rate ( i.e. , less damping when the migration slows down ) .
we adopt @xmath127 for series iii and
@xmath128 for series iv .
the fractions of cases with all four giant planets surviving on reasonable orbits are @xmath129 , @xmath130 , @xmath131 , and @xmath132 in series i iv , respectively .
they are all roughly consistent with the @xmath133 reported by @xcite , given the small number of simulations in tsiganis et al .
( @xmath134 simulations ) and in each of our series ( @xmath135 simulations ) .
the results from two typical simulations with all four giant planets surviving on reasonable orbits one from series i and the other from series iii are shown in figs .
[ fig1 ] and [ fig2 ] .
[ fig1 ] is an example where the ice giants switch positions . in each figure , panel a shows the evolution of the orbital semimajor axes @xmath136 , the perihelion distances @xmath137 , and the aphelion distances @xmath138 , while panels b , c , and d show the evolution of the orbital inclinations @xmath139 , the tilts of the spin axes from the @xmath98-axis of the inertial frame ( which is nearly perpendicular to the initial orbital planes of the planets ) , and the obliquities @xmath140 , respectively . it can be seen from the correlation of the changes in panels b and d of each figure that large changes in the obliquities of saturn and the ice giants during close encounters are due to changes in orbital inclinations .
the changes in the directions of the spin axes relative to inertial space during the encounters are minuscule ( panel c ) . as the inclinations
are damped to small values , the spin axes keep their orientations in inertial space , and the obliquities are similarly decreased .
these behaviors are exactly what we expect from the analytic argument in section 2 . for jupiter
, we note that both the obliquity and the tilt of the spin axis from the inertial @xmath98-axis increase to @xmath111@xmath141 degrees in figs .
[ fig1 ] and [ fig2 ] .
this could be due to secular spin - orbit coupling , because the spin precession due to solar torque is quite fast for jupiter ( @xmath92 ) , but a detailed examination of this process is beyond the scope of the present paper . among the cases with all four giant planets surviving on reasonable orbits ( @xmath142 out of @xmath143 simulations in all four series )
, there are only four cases where one or both of the ice giants have final obliquities greater than @xmath144 , including one case where one of the ice giants ( neptune ) has a final obliquity greater than @xmath145 ( @xmath146 ) .
however , these cases involve one or two extremely close encounters between the planets ( usually between saturn and the initially inner ice giant ) , for which the regular satellite systems are unlikely to survive .
even if the regular satellites could survive these encounters , their orbits would not be able to follow the equators of the planets during the encounters , and the final obliquities obtained in our simulations ( which include the contributions from the satellites ) should be reduced by a factor of @xmath147@xmath148 ( see section 2 ) and @xmath149 even in the most extreme case .
we have analyzed the evolution of the obliquities of the giant planets in the nice model @xcite , where the jupiter - saturn 2:1 resonance crossing led to close encounters among the giant planets and the orbital eccentricities and inclinations were eventually damped to their present values by the interactions with planetesimals .
we presented a simple analytic argument which shows that the change in the spin direction of a planet in inertial space during an encounter between the planets is very small and that the change in the obliquity ( which is measured from the orbit normal ) is due to the change in the orbital inclination .
since the inclinations are changed by encounters and damped by planetesimal interactions on timescales much shorter than the timescales on which the spins precess due to solar torques , especially for uranus and neptune , the obliquities return to small values if they are small before the encounters .
we have performed simulations using the symplectic integrator symba modified to include spin evolution .
the numerical results are consistent with the analytic argument leading to no significant remnant obliquities .
the analytic argument provides a physical explanation as to why the numerical results reported by @xcite , which are not confirmed by later simulations by him using another numerical code @xcite or the simulations in this paper , are indeed incorrect .
giant impacts in the late stages of the formation of uranus and neptune remain a plausible explanation for the obliquities of the ice giants , but a giant impact origin for saturn s obliquity is problematic because of its large mass and spin angular momentum @xcite .
alternatively , the obliquities of the giant planets could be generated by any process that twists the total angular momentum vector of the solar system on a timescale of @xmath150 @xcite .
however , the similarity between saturn s spin - axis precession rate and the nodal regression rate of neptune s orbit , and the near match of saturn s @xmath1 obliquity to that of the cassini state 2 of the secular spin - orbit resonance , strongly argue for the capture of saturn into the cassini state whose obliquity increases during the dispersal of the planetesimal disk @xcite .
we thank h. f. levison and k. tsiganis for informative discussions .
this research was supported in part by nasa grants nng05gk58 g and nng06gf42 g ( m.h.l . and s.j.p . ) , nasa grant nng04gj11 g ( w.r.w . ) , and nsf grant phy 99 - 07949 ( e.p . ) .
in this appendix we describe how the symplectic integrator symba @xcite is modified to include the evolution of the spin axes according to eq .
( [ dskdt ] ) and the tests that were performed .
our algorithm differs from the lie - poisson integrator for rigid body dynamics by @xcite in assuming principle axis rotation and handling close encounters .
symba is based on a variant of the @xcite method , with the gravitational @xmath86-body hamiltonian written in terms of positions relative to the sun and barycentric momenta , and employs a multiple time step technique to handle close encounters .
the potential of the gravitational interaction between planets @xmath151 and @xmath88 is of the form @xmath152 , which we simplify as @xmath153 in the following discussion . in symba , a set of cutoff radii @xmath154 is chosen , with @xmath155 a few times the mutual hill radius , and the potential @xmath153 is decomposed into @xmath156 , or equivalently the force @xmath157 into @xmath158 .
the properties of the partition functions @xmath159 are such that ( i ) @xmath160 ( except @xmath161 ) increases smoothly from zero at @xmath162 to one at @xmath163 and then decreases smoothly to zero at @xmath164 and ( ii ) @xmath161 increases smoothly from zero at @xmath165 to one at @xmath166 .
the force @xmath167 is to be applied with a time step @xmath168 , with @xmath169 an integer ( @xmath170 in the standard implementation ) .
a single step of overall time step @xmath171 of the symba algorithm can be represented by the following sequence of substeps : @xmath172 in the substep @xmath173 , each planet takes a linear drift in its heliocentric position ( corresponding to a linear drift in the position of the sun from the barycenter ) for time @xmath174 . in the substep @xmath175 , each planet receives a kick to its linear momentum due to the @xmath176 level forces from the other planets for time @xmath174 . in the recursive substep @xmath177 , a planet that is not having close encounters ( i.e. , a planet whose separation from any other planet is greater than @xmath155 ) evolves along a kepler orbit for time @xmath171 , while a pair of planets having an encounter have their time steps recursively subdivided to a maximum level of @xmath178 with the force at level @xmath17 , @xmath167 , applied with a time step @xmath168 if their separation @xmath179 during the overall step ( see @xcite for details ) . in eq .
( [ dskdt ] ) , the torque on the spin axis of planet @xmath88 from planet @xmath151 is of the form @xmath180 , which we simplify as @xmath181 in this discussion . as for the force @xmath157 , we decompose @xmath182 into @xmath183 using the partition functions @xmath159 , and @xmath184 is to be applied with a time step @xmath168 .
thus our modified algorithm ( with imposed migration and damping ) can be represented by the following sequence of substeps : @xmath185 in the substep @xmath186 , the orbital semimajor axis @xmath136 of each planet is changed according to the exact solution to the imposed migration rate ( with all of the other orbital elements fixed ) for time @xmath174 ( see @xcite for details ) .
similarly , the orbital eccentricity @xmath34 and inclination @xmath139 of each planet are changed according to the exact solutions to the imposed damping rates for time @xmath174 in the substep @xmath187 . in the substep @xmath188 , the spin of each planet
is evolved due to the solar torque ( i.e. , the first term in eq . ( [ dskdt ] ) ) alone for time @xmath174 , which is a rotation of @xmath87 by an angle @xmath189 about @xmath190 , because @xmath190 is fixed during this substep .
the substep @xmath191 is the same as @xmath175 in the original symba algorithm , but it also evolves the spin direction of each planet due to the @xmath176 level torques from the other planets for time @xmath174 . unlike the substep applying the solar torque alone , there is not an exact solution for the change in the spin direction with the torques from multiple planets , and we use the midpoint method .
similarly , @xmath192 is the same as @xmath177 , but it also applies the torque at level @xmath17 , @xmath184 , with a time step @xmath168 , recursively down to the maximum level @xmath178 , for a pair of planets having an encounter .
we have tested our implementation of the spin evolution with several tests . in the first set of tests
, we checked that the code produces the correct spin axis precession around the orbit normal in the presence of the solar torque alone .
we integrated jupiter alone with a variety of orbital eccentricity @xmath34 ( up to 0.2 ) .
we also integrated the four giant planets with their current @xmath34 and @xmath139 , but with their masses reduced by a factor of @xmath193 ( so that they are on unperturbed kepler orbits ) .
a variety of obliquities @xmath140 were used , and we integrated for @xmath194 using a time step of @xmath195 .
we found a small variation in @xmath140 ( up to @xmath196 degrees ) over the period of an orbit , which is expected since eq .
( [ dskdt ] ) is not orbit - averaged , but there was no detectable secular change in @xmath140 .
the average spin precession rate ( measured by the total change in the longitude of the ascending node of the equator on the orbital plane ) agreed with the analytic result @xmath197 to better than one part in @xmath198 . in the second set of tests
, we checked that the code produces the correct capture into ( and escape from ) secular spin - orbit resonance .
the simulations were simplified versions of the ones in @xcite .
we integrated saturn alone with a time step of @xmath199 .
initially , @xmath200 , @xmath201 and @xmath202 ( the last being the amplitude associated with the perturbation to saturn s orbital plane due to the nodal regression of neptune ) .
we imposed an orbital nodal precession rate of @xmath203 ( magnitude decreasing with time ) or @xmath204 ( magnitude increasing with time ) , with @xmath205@xmath206 . in the cases where @xmath207 was decreased from above @xmath208 to below @xmath208 ,
saturn s spin was captured into cassini state 2 , with the obliquity librating about the analytic result in @xcite . in the cases where @xmath207 was increased from below @xmath208 to above @xmath208 ,
the spin was first captured into cassini state 1 , with the obliquity librating about the analytic result in @xcite .
there was a jump in the obliquity when cassini state 1 disappeared , and the obliquity subsequently oscillated about a constant value .
the results agreed with the analytic theory and numerical results of @xcite and @xcite .
as a very stringent test of the spin evolution due to close mutual planetary interactions , we performed simulations similar to the binary planet test described in @xcite , where two planets are in a bound orbit and their center of mass orbits a star .
the center of mass of the binary was placed in a @xmath209 circular orbit about a solar - mass star .
the initial semimajor axis of the relative orbit of the binary was @xmath210 and the initial eccentricity was @xmath211 .
one planet had a mass of @xmath212 and the other @xmath213 .
both planets had the same precession constant as jupiter , and their initial obliquities were @xmath214 and @xmath215 .
we integrated this system for @xmath216 ( or about 16000 orbital periods of the binary ) . because the torques of the planets on each other dominated over the torques from the sun , the average precession rates of the spin axes around the normal to the relative orbit are known analytically , if we ignore the solar torques .
we found that the numerical precession rates agreed with the analytic results to within 0.0008 and 0.0022 fractionally for planets 1 and 2 , respectively .
the small discrepancies were not sensitive to the time step ( we used @xmath195 and smaller ) , and they are likely real and due to solar perturbations .
solar perturbations also caused the eccentricity of the relative orbit to vary between @xmath211 and @xmath217 and the obliquities to show small variations on the same timescale .
brunini , a. , 2006a .
origin of the obliquities of the giant planets in mutual interactions in the early solar system .
nature 440 , 11631165 .
brunini , a. , 2006b .
retraction : origin of the obliquities of the giant planets in mutual interactions in the early solar system .
nature 443 , 1013 .
chiang , e. , lithwick , y. , murray - clay , r. , buie , m. , grundy , w. , holman , m. , 2006 . a brief history of trans - neptunian space . in : reipurth , b. , jewitt , d. , keil , k. ( eds . ) , protostars and planets v. univ . of arizona press , tucson , in press .
dones , l. , tremaine , s. , 1993 . on the origin of planetary spins .
icarus 103 , 6792 .
duncan , m. j. , levison , h. f. , lee , m. h. , 1998 .
a multiple time step symplectic algorithm for integrating close encounters .
j. 116 , 20672077 .
goldreich , p. , 1965 .
inclination of satellite orbits about an oblate precessing planet .
j. 70 , 59 .
goldreich , p. , lithwick , y. , sari , r. , 2004 .
planet formation by coagulation : a focus on uranus and neptune .
42 , 549601 .
hamilton , d. p. , ward , w. r. , 2004 .
tilting saturn .
ii . numerical model .
j. 128 , 25102517 .
laskar , j. , jacobson , r. a. , 1987 .
an analytical ephemeris of the uranian satellites .
188 , 212224 .
lee , m. h. , peale , s. j. , 2002 .
dynamics and origin of the 2:1 orbital resonances of the gj 876 planets .
j. 567 , 596609 .
lee , m. h. , peale , s. j. , pfahl , e. , ward , w. r. , 2006 .
evolution of the obliquities of the giant planets during migration .
lissauer , j. j. , safronov , v. s. , 1991 .
the random component of planetary rotation .
icarus 93 , 288297 .
touma , j. , wisdom , j. , 1994 .
lie - poisson integrators for rigid body dynamics in the solar system .
j. 107 , 11891202 .
tremaine , s. , 1991 . on the origin of the obliquities of the outer planets .
icarus 89 , 8592 .
tsiganis , k. , gomes , r. , morbidelli , a. , levison , h. f. , 2005 .
origin of the orbital architecture of the giant planets of the solar system .
nature 435 , 459461 .
ward , w. r. , hamilton , d. p. , 2004 . tilting saturn . i. analytic model .
j. 128 , 25012509 .
wisdom , j. , holman , m. , 1991 .
symplectic maps for the n - body problem .
j. 102 , 15281538 . | tsiganis et al . [ tsiganis , k. , et al . , 2005 .
nature 435 , 459461 ] have proposed that the current orbital architecture of the outer solar system could have been established if it was initially compact and jupiter and saturn crossed the 2:1 orbital resonance by divergent migration .
the crossing led to close encounters among the giant planets , but the orbital eccentricities and inclinations were damped to their current values by interactions with planetesimals .
brunini [ brunini , a. , 2006 .
nature 440 , 11631165 ] has presented widely publicized numerical results showing that the close encounters led to the current obliquities of the giant planets .
we present a simple analytic argument which shows that the change in the spin direction of a planet relative to an inertial frame during an encounter between the planets is very small and that the change in the obliquity ( which is measured from the orbit normal ) is due to the change in the orbital inclination .
since the inclinations are damped by planetesimal interactions on timescales much shorter than the timescales on which the spins precess due to the torques from the sun , especially for uranus and neptune , the obliquities should return to small values if they are small before the encounters .
we have performed simulations using the symplectic integrator symba , modified to include spin evolution due to the torques from the sun and mutual planetary interactions .
our numerical results are consistent with the analytic argument for no significant remnant obliquities . |
despite great progress in pharmacotherapy and interventional treatment , acute coronary syndromes ( acs ) remain the major cause of mortality and morbidity in the modern world .
inflammation plays a key role in the initiation and promotion of atherosclerotic lesions and can trigger acs by the induction of plaque instability .
c - reactive ( crp ) protein is an extensively studied inflammatory factor whose prognostic value in cardiovascular diseases in recent years has become increasingly important [ 27 ] . additionally , crp is no longer merely considered a marker but also emerges as a mediator of atherosclerosis [ 8 , 9 ] .
thus , considering the generally available lipid profile a tool for risk assessment , it seems that crp and the lipid profile besides the patient 's clinical characteristics could lead to the most tangible benefit for assessing the risk of acs development . on the other hand , in recent years
the value of crp in this setting has been extensively debated . in a large meta - analysis of 22 prospective studies in healthy individuals , danesh et al . found that in studies published after 2000 , the prognostic value of crp in predicting acs was much weaker than in a meta - analysis of research results from before 2000 .
this led to a critical review of the role of crp in the assessment of occurrence of cardiovascular events and less optimistic application of its determination for the primary and secondary prevention [ 10 , 11 ] .
in contrast with these data , a recent individual participant meta - analysis of 160,309 patients confirmed substantial continuous associations between crp concentration and the risks of acs , ischaemic stroke , and vascular mortality .
one of the best known risk factors and a primary target of therapy is elevated concentration of low - density lipoprotein cholesterol ( ldl - c ) . despite many studies indicating the need for determination of ldl - c in patients at risk of acs
, it is more and more often suggested that focusing solely on ldl - c is not an optimal diagnostic and therapeutic strategy .
triglyceride - rich lipoproteins , including very low - density lipoproteins ( vldl ) and intermediate - density lipoproteins ( idl ) , also exert atherogenic properties .
patients , who achieved a reduction in ldl - c even below 70 mg / dl , still are at the so - called residual risk of atherothrombotic events .
atherogenic factors that influence this residual risk consist of elevated idl and vldl levels and the presence of small dense ldl particles , which are not detected in a basic lipid panel .
the coexistence of high triglycerides ( tg ) and low high - density lipoprotein cholesterol ( hdl - c ) , called atherogenic dyslipidemia , is associated with elevated apolipoprotein b concentration .
while the role of apolipoproteins in coronary risk assessment is an evolving debate , the apob : apoa - i ratio is becoming increasingly important [ 14 , 15 ] .
the results of the amoris and interheart studies demonstrated that the apob : apoa - i ratio was the strongest predictor for myocardial infarction among all investigated variables and most importantly , like crp , was able to identify subjects at high risk even when ldl - c values were considered normal [ 16 , 17 ] . as the routine determination of apolipoproteins and crp in acs risk stratification remains controversial , this study aims to investigate whether evaluation of these markers enhances , besides the traditional lipid profile , the assessment process for the risk of acs development .
we screened consecutive patients admitted due to the initial diagnosis of acs to the department of cardiology and internal medicine at the university hospital in bydgoszcz within the first 6 hours from the onset of chest pain .
the exclusion criteria were as follows : ( i ) chronic heart failure ( new york heart association class ii
iv ) , ( iii ) pulmonary embolism within 6 months preceding the enrolment , ( iv ) creatinine concentration > 176.8 mmol / l , ( v ) acs within 6 weeks preceding the enrolment , ( vi ) the presence of features suggestive of an active inflammatory process on admission , and ( vii ) therapy with steroids , immunosuppressive agents , and nonsteroidal anti - inflammatory drugs ( excluding low doses of aspirin ) . among 267 subjects , who fulfilled the requirements of the study according to the inclusion and exclusion criteria ,
47 patients were diagnosed with unspecified chest pain or other heart diseases and were excluded from further analysis .
the final study group consisted of 220 patients ( 91 females and 129 males , aged 64 12 years ) .
patients with acs were subsequently definitely diagnosed with unstable angina ( ua ; n = 96 ) , non - st - elevation myocardial infarction ( nstemi ; n = 57 ) , or st - elevation myocardial infarction ( stemi ; n = 67 ) .
clinically healthy volunteers ( 61 women and 55 men , aged 52 9 years ) with no evidence of present renal , metabolic or inflammatory disease , heart failure , and recent myocardial infarction served as controls .
dyslipidemia was defined by at least one abnormal level of serum lipid parameters : total cholesterol ( tc ) > 5.2 mmol / l , tg > 1.7 mmol / l , ldl - c > 2.6 mmol / l , hdl - c < 1.3 mmol / l for women and < 1.0 mmol / l for men according to the modified definition of third report of the national cholesterol education program .
hypertension was diagnosed if systolic blood pressure exceeded 140 mmhg and/or diastolic blood pressure was above 90 mmhg .
the study protocol was approved by the bioethics committee at nicolaus copernicus university in torun collegium medicum in bydgoszcz and written informed consent was obtained from all patients and controls .
venous blood samples were collected from patients on hospital admission within 6 hours of chest pain onset .
serum was assayed on admission for cardiac troponin i ( ctni ) and lipid parameters ( architect ci8200 , abbott diagnostics ) . any increase of ctni above 0.032 ng / ml ( the 99th percentile for the healthy population measured with a 10% coefficient of variation ) was considered a positive result .
high - sensitivity crp ( hscrp ) was measured using the bn ii system nephelometer ( n high - sensitivity crp ; siemens healthcare diagnostics , deerfield , il , usa ) , providing excellent precision with the coefficient of variation reported by the manufacturer of less than 10% .
coefficients of variation for hscrp estimated in our laboratory were below 3.5% and below 4.5% for hscrp concentrations below 1
mg / l and above 3 mg / l , respectively . the lower limit of crp detection was 0.17
serum apoa - i and apob100 concentrations were measured in samples stored frozen at 80c no longer than 6 months ( architect ci8200 ) and the ratio of apob : apoa - i was calculated .
tc : hdl - c < 4 and tg : hdl - c <3 were regarded as optimal . according to walldius and jungner the apob : apoa - i ratio over 0.8 for women and 0.9 for men was considered to represent high risk ofacs .
crp concentrations for the first 100 patients in the study group and for the first 50 patients in the control group were , respectively , 5.55 7.19 and 1.41 1.61 mg / l . based on these results and
assuming a 2-sided alpha value of 0.05 , we calculated that enrolment of 220 patients in the study group and 116 patients in the control group would provide a 99.8 power to demonstrate a significant difference in crp concentrations between patients with and without acs .
we decided to obtain such high power to be able to conduct credible multivariate analyses .
the kolmogorov - smirnov test was used to assess normality of distribution of investigated parameters .
variances in the two groups with normal distribution were examined using the levene 's test .
comparison between the groups was performed by using the chi - square test for categorical variables , the unpaired student 's t - test , anova followed by the tukey test for normally distributed variables , and the mann - whitney u - test and the kruskal - wallis test for nonnormally distributed variables , with the post hoc dunn 's tests .
logistic regression was performed to determine associations between baseline parameters and the risk of acs development .
clinical utility of laboratory parameters was determined by analysis of receiver operating characteristic ( roc ) curves . statistical analysis and sample size calculation
were performed using spss 17.0 software package ( spss , chicago , il , usa ) and statistica 10.0 for windows ( statsoft , tulsa , ok , usa ) .
baseline characteristics of the study participants , including lipid parameters , crp , and apolipoproteins concentrations constituting major cardiovascular risk factors , are shown in table 1 .
patients with acs , compared with controls , had higher concentrations of tc , ldl - c , non - hdl - c , and tg , but lower levels of hdl - c and apoa - i .
they also presented significantly higher values of atherogenic indexes such as tc : hdl - c , ldl - c : hdl - c , apob : apoa - i , and tg : hdl - c , reflecting insulin resistance , as well as fourfold higher median concentration of c - reactive protein in comparison with the control group .
a quarter of acs patients were diagnosed with type 2 diabetes . in the course of further analysis the patients were divided into groups based on the specific clinical diagnosis ( table 2 ) .
ua patients formed the largest group , also characterized by lower age compared with those with stemi and nstemi .
statistically significant differences between the ua and stemi groups were found for ldl - c , non - hdl - c and the ldl - c : hdl - c , ratio .
apob concentration and the apob : apoa - i ratio were substantially higher in stemi patients compared with the ua and nstemi groups , while between the latter two no major differences were found .
crp concentration was markedly higher in patients with stemi and nstemi compared with those with ua .
correlation analysis showed no significant relationships between serum crp and other variables in the control group .
in contrast , in the acs group , weak but statistically significant correlations were observed between crp concentration and the apob : apoa - i ratio ( r = 0.16 ; p = 0.02 ) , the tg : hdl - c ratio ( r = 0.15 ; p = 0.02 ) , the ldl - c : hdl - c ratio ( r = 0.15 ; p = 0.02 ) , and the tc : hdl - c ratio ( r = 0.14 ; p = 0.03 ) , respectively .
also a weak but statistically significant negative correlation between crp and hdl - c ( r = 0.14 ; p = 0.04 ) was found in this group .
the odds ratio for the occurrence of acs among the conventional risk factors was highest for hypertension , then followed by age , dyslipidemia , and smoking ( table 3 ) .
the probability of acs occurrence , depending on the measured laboratory parameters and calculated ratios , was presented using logistic regression after adjustment for age , gender , and smoking status successively . in order to avoid data redundancy , the variables have been divided into primary variables ( table 4 ) and secondary variables ( data not presented ) .
measured analytes have been identified as the primary variables , while variables resulting from calculations of other parameters were classified as secondary .
the estimator of risk for acs occurrence was the logistic odds ratio , which was given along with a 95% confidence interval and significance level .
the first model designed , model 0 unadjusted , was highly significant and based on the result of a pseudomeasure of quality of the fit - r nagelkerke explained 47% of the variation for acs occurrence . in this model , all tc , hdl - c , ldl - c , tg , apoa - i , and apob did not facilitate the risk stratification for acs development . only crp significantly increased the probability of the occurrence of acs ( by 60% ) .
model 1 after adjustment for age was also highly significant and explained approximately 74% of the variation for the presence of acs . among the primary variables only crp increased the risk of acs ( by approximately 55% ) .
another model , which was also highly significant and explained approximately 75% of the variability for acs development , was designed after adjustment for age and sex .
tc affected the risk of acs in 12% , whereas hdl - c and apoa - i markedly lowered this risk . in this model ,
the last of the models , model 3 for the primary variables , was adjusted for age , sex , and smoking status .
this model was also highly significant and explained approximately 86% of the variation for the presence of acs .
table 5 displays the results of logistic regression models with both the primary and secondary variables .
size distortions associated with the collinearity of independent quantitative variables depended on the value of the correlation coefficient between the two variables . a preliminary analysis of correlations between lipid variables from table 5 revealed only moderate strength of the correlation coefficients between these variables .
in addition , we run a tolerance analysis that indicated that these variables can be tolerated in the model .
model 0 , adjusted neither for age , sex , nor smoking , was highly significant and based on the result of a pseudo measure of quality of the fit - r nagelkerke explained 49% of the variation for the presence of acs .
in this model , crp was the only significant predictor for the occurrence of acs , increasing the probability of disease by 60% .
model 1 , after adjustment for age , was highly significant and explained 75% of variation for acs development . in this model ,
while the predictive value of crp alone in model 1 was 56% , adjustment for age and sex , as performed in model 2 , increased it to 64% .
the highest odds ratio for acs occurrence was obtained in model 3 ( including adjustment for age , sex , and smoking status ) for the primary and secondary variables .
this model was also highly significant and explained 90% of variation for the presence of acs . in this model , elevated crp concentration nearly doubled the likelihood of acs .
finally , we evaluated the roc curves to assess diagnostic accuracies of investigated variable for the prediction of acs occurrence .
the highest level of discrimination of acs was found for crp ( area under the curve [ auc ] = 0.80 ) , however , this was not significantly different from the diagnostic accuracy of three other variables : tc : hdl - c ( auc = 0.78 ) , ldl - c : hdl - c , and tg : hdl - c ( auc = 0.77 ) .
for all measured parameters sensitivity , specificity , positive predictive value , and negative predictive value were calculated . among them ,
the most valuable results were obtained for c - reactive protein and lipid ratios ( table 6 ) .
a roc analysis revealed an optimal cut - off point for crp of 0.85 mg / l .
our study clearly indicates that crp possesses a higher prognostic value in terms of acs prediction than apolipoproteins and lipid profile .
the difference in crp level between patients with and without acs was much more pronounced in our data than for apolipoproteins and lipid parameters and remained significant after adjustment for age , sex , and smoking status .
furthermore , assessment of the diagnostic accuracy confirmed a very good ability of crp to discriminate between cases and controls . to increase the robustness of our findings we enrolled into our study only patients diagnosed with acs within first 6 hours from the onset of chest pain .
we established this time frame restriction in the inclusion criteria to minimize a potential impact of necrosis - related inflammatory reaction on crp concentration .
elevated crp concentration in patients who presented to hospital with chest pain due to acs was previously demonstrated by others [ 19 , 20 ] . in our study the highest crp levels were observed in nstemi and stemi patients and were considerably higher than in ua patients .
these observations are consistent with results of other researchers showing higher crp concentrations in patients with myocardial infarction than with stable or unstable coronary artery disease [ 1922 ] .
additionally , some investigators have reported crp levels to be higher in patients with stemi than in those with nstemi and noted their further and significant decrease in patients with ua [ 21 , 23 ] . however , in these trials blood sampling beyond 6 hours from the onset of chest pain was in agreement with the study protocols .
therefore , the observed variation in crp concentrations among the types of acs might be at least partially attributed to the differences in the area of the infarcted myocardium . on the other hand ,
there are also reports demonstrating lack of significant differences in crp concentrations at baseline among patients with acs [ 24 , 25 ] .
it should be also acknowledged that elevated crp concentration on admission is suggested to be a marker for anatomic complexity of culprit lesions [ 23 , 24 ] .
crp concentration above 3 mg / l , close to this present in our acs patients , is currently recommended by the centers for disease control and prevention ( cdc ) and the american heart association ( aha ) as an independent predictor of cardiovascular events in patients at intermediate global risk ( class of recommendation iia , level of evidence b ) .
nevertheless , the optimal cut - off point for hscrp test determined by roc analysis in our study was 0.85 mg / l .
this may indicate a higher diagnostic value of the test for low concentrations of crp .
our cut - off point is close to 1 mg / l , being a lower limit for the intermediate risk category according the cdc and aha statement .
calculations performed using our data for the cut - off point of 3 mg / l revealed a slightly lower sensitivity but higher specificity than for the cut - off point of 0.85 mg / l . in line with our findings , the results of the jupiter trial support lower than 3 mg / l cut - off point for increased cardiovascular risk . in this randomized , placebo - controlled study of 17,802 apparently healthy persons with ldl - c concentration below 2.6
mg / l or higher , rosuvastatin significantly reduced the incidence of major cardiovascular events .
interestingly , another recent study has addressed the prognostic efficacy of hscrp in acs patients presenting within 6 hours from the onset of chest pain and identification of the optimal cut - off value to determine the long - term prognosis . in this cohort hscrp level above 1.1
our study group , diagnosed with acs , was diverse in terms of established risk factors including dyslipidemia , hypertension , diabetes , and smoking ; each of them is capable of explaining the occurrence of high crp concentrations .
acs patients have a higher risk of subsequent cardiovascular events , featuring myocardial infarction , stroke , and death .
primary and major strategies to diminish premature cardiovascular morbidity and mortality should include the identification and treatment of established risk factors , especially hypertension , dyslipidemia , smoking , obesity , and diabetes .
although the study group was characterized by dyslipidemia , the median concentrations of lipids , except for ldl - c and non - hdl - c , were within normal limits . also , the median concentration of apolipoprotein a - i and apob remained normal .
the calculated atherogenicity indexes , except for tc : hdl - c and ldl - c : hdl - c , also did not exceed the reference values . however , although remaining within normal ranges , there were statistically significant differences concerning all parameters , compared with the control group . it might be explained by the lower prevalence of risk factors in the control group , since as evidenced by the baseline characteristics , the prevalence of dyslipidemia , hypertension , and smoking in this group was significantly lower and there were no patients with diabetes .
the reduced values of the lipid parameters could be also due to statin therapy , which in the study group was received by 69% of patients prior to admission . despite ongoing statin therapy
the residual cardiovascular risk can still be significant in patients with dyslipidemia . in our study
, significant correlations between crp and atherogenic indexes were observed only among those diagnosed with acs . as we know
, these indicators demonstrate the atherogenicity and the presence of small dense ldl as well as insulin resistance .
there is growing evidence that targeting other lipids , such as triglycerides and hdl - c , is an important way to reduce the residual cardiovascular risk , particularly in patients with frank metabolic dysfunction . in our study
we observed that out of the basic lipids and apolipoproteins only hdl - c and apoa - i importantly limited the risk of cardiovascular events , but not in every model , and that after switching to models incorporating the secondary variables such as atherogenicity indexes , this effect was negligible .
in contrast , we found that crp significantly improved risk prediction models ' accuracy and that it was the strongest predictor of acs in each of the logistic regression models designed .
acs risk was highest for crp compared with the lipid parameters , atherogenicity indexes , and apolipoproteins ( odds ratio = 1.9 ) in the model designed after adjustment for age , sex , and smoking .
to the best of our knowledge , despite the large number of publications on crp , to date only few studies have been published concerning the clinical utility of crp in comparison with apolipoproteins and simple lipid indexes calculated on the basis of the routine lipid profile . based on a subanalysis of the
prove it - timi 22 trial including acs patients receiving statin therapy , ray et al . concluded that the addition of hscrp to lipid - based measurements significantly improved risk prediction , while apob : apoa - i , tc : hdl - c , non - hdl - c and ldl - c provided a similar risk prediction accuracy .
in contrast , the interheart case - control study suggested that apob : apoa - i provides the highest odds ratio for myocardial infarction occurrence compared with ldl - c and tc : hdl - c , . in the present study ,
crp significantly improved risk prediction irrespective of lipids , apolipoproteins , and their calculated ratios included .
moreover , based on roc curve analysis , crp becomes the most important discriminator of acs cases compared with other parameters . besides the role of crp , considering the discrimination power assessed by roc analysis , also tc : hdl - c , ldl - c : hdl - c , and tg : hdl - c showed similar and significant performance for acs prediction .
the discrimination power was assessed quantitatively as the auc , which was 0.80 for crp , 0.78 for tc : hdl - c and 0.77 for ldl - c : hdl - c , and tg : hdl - c .
the aucs for crp in the nphs - ii trial and in the eas trial were 0.61 ( 95% confidence interval 0.570.66 ) and 0.62 ( 95% confidence interval 0.570.67 ) , respectively .
however , in these studies the measurement of crp at baseline was performed in healthy individuals and perhaps due to this fact it provided only limited discrimination for cardiovascular events compared with the population burdened with additional risk factors . in our study
we failed to demonstrate any relation of apob and apob : apoa - i with the onset of the cardiovascular event .
the lack of influence of apolipoproteins and the lipid ratios on the occurrence of acs could be explained by the earlier use of statins in approximately 70% of patients ; however , it is not consistent with the fact that statins also decrease crp level independently of lowering ldl - c and apob concentrations .
this leads to the suggestion of the pivotal role of inflammation in comparison to the subsidiary involvement of small dense atherogenic lipoproteins in the process leading to acs .
finally , it remains an unsolved issue whether crp directly contributes to atherothrombotic events and may be a potential therapeutic target , or if it just reflects an increased risk for unfavourable outcome as a bystander marker [ 8 , 9 ] .
a large body of basic scientific evidence suggests that crp possesses proatherogenic features . as demonstrated by williams et al .
, crp increases the activity of matrix metalloproteinase 1 and collagenases produced by monocytes and macrophages , which contributes to the destabilization of atherosclerotic plaque .
another study demonstrated a positive correlation between the intensity of staining for the presence of crp in atherosclerotic lesions in coronary arteries , the concentration of this protein in plasma , and the number of unstable plaques with a thin fibrous cap .
forte et al . showed that in patients with acs , crp is produced and released within the coronary circulation , which is associated with impairment of endothelial function .
first , findings of our study due to its case - control design associated with the potential for confounding may be rather hypothesis - generating than definitive .
second , our cases and controls slightly differed in terms of age and gender distribution .
however , the strength of the association between crp concentration and the acs occurrence in our study was even greater after adjustment for these variables .
third , we enrolled a broad spectrum of acs patients and detailed estimation of the relationship between crp concentration and the acs occurrence may vary among different acs types .
however , our inclusion criteria reflect a real - world setting and at the early stage of acs , when we collected blood samples , it is usually unlikely to differentiate between nstemi and ua .
fourth , we can not exclude the modulatory effect of prior statin therapy given in a substantial proportion of cases on the obtained results .
fifth , we accounted in our calculations neither for diurnal and seasonal variations in crp concentration nor for physical activity of the study participants .
sixth , in our study we evaluated exclusively crp , apolipoproteins , and the traditional lipid profile .
it remains unclear whether novel biomarkers such as high - sensitivity cardiac troponins , myeloperoxidase , growth differentiation factor-15 , and interleukin 1 receptor - like 1 ( st2 ) possess an additional predictive value to that obtained from crp measurement and validated risk scores [ 39 , 40 ] .
our study indicates that crp superiorly to apolipoproteins and lipid profile facilitates the risk stratification for acs occurrence
. however , large prospective cohort trials are required to verify our findings and assess whether novel biomarkers possess an additional predictive value to that obtained from crp measurement and validated risk scores . | objective . to investigate whether assessment of c - reactive protein ( crp ) and apolipoproteins ,
besides the traditional lipid profile , enhances the assessment process for the risk of acute coronary syndrome ( acs ) .
methods .
the study group consisted of 220 consecutive patients admitted to hospital within the first 6 hours from the onset of chest pain .
patients were diagnosed with unstable angina ( n = 96 ) , non - st - elevation myocardial infarction ( nstemi ; n = 57 ) , or st - elevation myocardial infarction ( stemi ; n = 67 ) .
acs patients were compared with 116 healthy volunteers in a case - control study .
the serum was assayed on admission for crp , apolipoproteins apoai and apob100 , and lipid parameters .
results .
the highest concentrations of crp were found in nstemi and stemi , with a median value four - fold higher in acs patients than in controls ( p < 0.0001 ) . only crp significantly increased the probability of acs development ( adjusted odds ratio for a 1 mg / l increase 1.90 ; 95% confidence interval [ ci ] 1.342.89 ) and explained 90% of the variation for acs development .
similarly , we demonstrated the highest diagnostic accuracy for crp among all investigated markers ( area under the curve 0.80 ; 95% ci 0.750.85 ) .
conclusions .
our study indicates that crp superiorly to apolipoproteins and lipid profile facilitates the risk stratification for acs occurrence . |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Prevention of Escapement of
Genetically Altered Salmon in the United States Act''.
SEC. 2. PROHIBITION ON SALE OF GENETICALLY ALTERED SALMON.
(a) Prohibition.--It shall be unlawful for a person--
(1) to ship, transport, offer for sale, sell, or purchase a
covered fish, or a product containing covered fish, in
interstate or foreign commerce;
(2) to have custody, control, or possession of, with the
intent to ship, transport, offer for sale, sell, or purchase a
covered fish, or a product containing covered fish, in
interstate commerce;
(3) to engage in net-pen aquaculture of covered fish;
(4) to release a covered fish into a natural environment;
or
(5) to have custody, control, or possession of a covered
fish with the intent to release it into a natural environment.
(b) Exception.--Subsection (a) shall not apply to a fish, fish
part, or product--
(1) under confined use, or intended for confined use, for
scientific research;
(2) collected for the purpose of enforcing this Act; or
(3) if the Under Secretary of Commerce for Oceans and
Atmosphere, in consultation with the Director of the United
States Fish and Wildlife Service and any other Federal, State,
or tribal entity the Under Secretary considers appropriate,
reviews any application requesting an action by a department or
agency of the Federal government to permit an act prohibited
under subsection (a), including any environmental assessment
prepared as part of that application, and--
(A) prepares a finding of no significant impact in
accordance with the National Environmental Policy Act
of 1969 (42 U.S.C. 4321 et seq.); or
(B) finds the application to be consistent with an
environmental impact statement prepared by the Under
Secretary in accordance with section 102(2)(C) of the
National Environmental Policy Act of 1969 (42 U.S.C.
4332) that includes--
(i) an environmental risk analysis that
assesses the potential direct and indirect
impacts from escapement of covered fish on wild
and cultured fish stocks and environments that
may be exposed to such covered fish;
(ii) a failure mode and effects analysis
that quantitatively assesses the best- and
worst-case probabilities of failure of each
applicable confinement technique;
(iii) an assessment of the costs of control
or eradication of escaped covered fish; and
(iv) an assessment of the potential
economic damage in terms of loss of production
or sales to relevant wild and cultured fish
stocks and environments from the escapement of
covered fish.
(c) Environmental Impact Considerations.--
(1) Notice.--Each agency, department, or other unit of the
Federal Government shall promptly notify the Under Secretary of
Commerce for Oceans and Atmosphere when an action involving
covered fish, or a product containing covered fish is first
identified by such unit.
(2) Ensuring compliance.--The Under Secretary of Commerce
for Oceans and Atmosphere, in cooperation with each Federal,
State, or tribal entity that the Under Secretary considers
appropriate, may monitor any mitigation measures proposed under
subsection (b)(3) to ensure implementation and compliance
therewith.
(3) Provisions as complementary.--The provisions of this
Act are in addition to, and shall not affect the operation of,
other Federal, State, or local laws regulating a covered fish,
or a product containing covered fish.
(d) Rules and Regulations.--The Secretary shall prescribe such
rules and regulations as the Secretary considers necessary to carry out
the provisions of this Act.
SEC. 3. ENFORCEMENT AND PENALTIES.
(a) Enforcement.--The Secretary of Commerce may enforce section 2
in the same manner, by the same means, and with the same jurisdiction,
powers, and duties provided under sections 308, 309, 310, and 311 of
the Magnuson-Stevens Fishery Conservation and Management Act (16 U.S.C.
1858, 1859, 1860, and 1861).
(b) Penalties.--A person who violates section 2 shall be subject to
the penalties, and entitled to the privileges and immunities, under
sections 308, 309, 310, and 311 of the Magnuson-Stevens Fishery
Conservation and Management Act (16 U.S.C. 1858, 1859, 1860, and 1861).
SEC. 4. REPORT ON RISKS TO WILD FISH STOCKS.
Not later than 180 days after the date of enactment of this Act,
the Under Secretary of Commerce for Oceans and Atmosphere shall
transmit to the Committee on Commerce, Science, and Transportation of
the Senate and the Committee on Natural Resources of the House of
Representatives the report under section 1007 of the Food and Drug
Administration Amendments Act of 2007 (21 U.S.C. 2106).
SEC. 5. DEFINITIONS.
In this Act:
(1) Confined use.--The term ``confined use'' means any
operation, undertaken within a secured, land-based facility,
that involves a covered fish controlled by specific measures
that effectively prevent the covered fish from having contact
with and impact on the external environment, including
biological and physical confinement measures.
(2) Covered fish.--The term ``covered fish'' means any
finfish, live or dead, including the gametes, fertilized eggs,
offspring, and descendants thereof, that is modified or
produced through the application of recombinant
deoxyribonucleic acid (DNA) technologies, using DNA from an
organism's own genome or that of another species, that overcome
natural physiological reproductive barriers and that are not
techniques used in traditional breeding and selection.
(3) Finding of no significant impact.--The term ``finding
of no significant impact'' has the meaning given the term in
section 1508.13 of title 40, Code of Federal Regulations.
(4) Product.--The term ``product'' means an item
manufactured or produced for sale or use as food. | Prevention of Escapement of Genetically Altered Salmon in the United States Act This bill prohibits a person from: shipping, transporting, offering for sale, selling, or purchasing a genetically altered finfish, or a food product containing those fish, in commerce; having custody, control, or possession of those fish or food products with the intent to ship, transport, offer for sale, sell, or purchase them in commerce; engaging in net-pen aquaculture (pens of fish contained by nets) of those fish; releasing those fish into a natural environment; or having custody, control, or possession of those fish with the intent to release them into a natural environment. Fish, fish parts, or products confined for scientific research or collected to enforce this Act are exempted from the prohibition. An additional exemption is established if the National Oceanic and Atmospheric Administration (NOAA): (1) prepares a finding of no significant impact in accordance with the National Environmental Policy Act of 1969 after reviewing an application requesting a federal agency to permit activity prohibited by this Act, or (2) finds the application to be consistent with an environmental impact statement that includes an environmental risk analysis and specified assessments of costs and potential economic damage. Each federal agency must promptly notify NOAA when an action involving those fish or food products is first identified by the agency. The Department of Commerce may enforce penalties for violations of this Act under specified provisions of the Magnuson-Stevens Fishery Conservation and Management Act. |
amorphous magnetic wires are of interest for their actual and potential use , e. g. in sensors @xcite . as it is almost usual in micromagnetism , their properties depend on the technique of sample preparation and thermal treatment . then , they are a good subject for computational science . the problem of the stray field and/or magnetization distribution of the wire have been treated either by means of a purely computational methods , where the wire volume is divided into magnetically polarized units @xcite , or within the dipolar or similar model approximation @xcite .
the latter approach is particularly suitable for magnetic arrays , formed as sets of parallel microwires perpendicular to the array @xcite .
other authors used an approximation of a homogeneous interaction field @xcite . as it was pointed out by velazquez et al .
@xcite , the homogeneous field does not work for short interwire distances .
moreover , in fact the spatial distribution of the magnetization near the wire ends remains unknown ; and it is precisely in this area where the remagnetization process starts . as a consequence , our knowledge on the subtle process of the switching of the magnetic moment in the wire advances with difficulties , despite an obvious interest motivated by technology .
recent progress in the field is due to an application of some phenomenological theories , and by the obtained accordance of the results with experimental data @xcite . although this procedure improved much our understanding of the underlying physical mechanisms , still questions seem to be not much less valuable than answers . here
we are interested in the bistable hysteresis loops for various orientations of the wires with respect to each other and to the applied field .
the motivation is the potential flexibility of the hysteresis loops , which we expect to result when we modify mutual positions and orientations of the wires . on the other hand , it is desirable to confront the experimental data with the model calculations .
even simplified , the model provides a reference point , and the departures between model and reality tells us where an established picture fails .
our method here is to use a simplified model of the interaction , where the wires are magnetized homogeneously and the wire diameter is set to zero .
this leaves the stray field of a wire reduced to the field created by two magnetic charges , placed at the wire ends .
the approximation of an infinitely thin wire is justified as long as the wire - wire distance is much larger than the wire diameter .
the resulting formula is more refined than the approximation of a homogeneous field , and much easier to use than the micromagnetic simulation .
this advantage allows to calculate the interaction field for any mutual position and/or orientation of the wires . despite of its practical ease
, there is an additional methodological argument for the assumption on the homogeneous distribution of the magnetization .
let us suppose the case of two parallel wires , which form two edges of a rectangle .
this system has been investigated by several authors @xcite .
the experimental results on the hysteresis clearly prove that the stray field of the wires act as to prefer the antiparallel orientations of their magnetic moments .
it is reasonable to expect that the stray field of one wire acting at another wire should be evaluated near the end of the latter wire ; it is at this point where the remagnetization process starts .
then , every deviation from the homogeneous distribution of the magnetization weakens the interaction field , what makes the model uneffective .
let us add that in our numerical simulations reported from section 3 we are going to evaluate the interaction field not near the wires ends , but at the wires ends .
this simplification is expected not to change results remarkably as long as the wires are not parallel .
we are interested in two questions : i ) which geometrical configurations of the wires allow for the bistability , ii ) what kinds of the hysteresis loops appear for various wire configurations ? the former question appears as a consequence of the fact , that for some mutual positions and orientations of the wires , the effective ( external + interaction ) field causing the large barkhausen jump at one wire end changes its sign at a point along of the wire ; then the domain wall is stopped at this point and the bistability is lost . in this case
some more complex behaviour of the hysteresis loop can be expected ; for clarity we limit the subject of this text to the bistable case . the second question is a necessary introduction to consider magnetic properties of sets of magnetostatically interacting elements .
such systems are of potential interest e.g. for submicrometer magnetic dots @xcite .
we hope that the answer , even simplified , will activate the search of spatial configurations of the wires which can be useful for other new applications .
the condition applied here can seem to be too restrictive , because in fact the bistability can still be observed if the point at the wire where the field along the wire is zero may vanish at an increasing applied field before the domain wall reaches it . here , however , we are not going to rely on these dynamical effects .
we limit our interest to the cases where the bistability is observed even in the limit of small frequency , and the field amplitude only as large as to activate the switching process . on the other hand , it is known that at field below the order of 1 a / m the domain wall motion is much slower .
however , this effect does not influence the shape of the hysteresis loop as long as the period 1/@xmath9 of the applied sinusoidal field is larger than the time of the remagnetization .
our discussion is limited to this case .
it is known that the wire properties depend on the applied tensile stress @xcite . for the purposes of this work , most important
agent is the stress dependence of the switching ( coercive ) field .
we should repeat here that the condition of the bistability considered in this text is applied for the effective field ( applied field + interaction ) which triggers the domain wall motion .
the enhancement of the switching field by the tensile stress demands an increase of the external field , what influences the bistability condition .
then we consider the tensile stress as an important and nontrivial factor which can change the system properties .
the layout of this text is as follows . in the next section
the data are provided on the experimental dependence of the switching field of the wire on the applied tensile stress . in section 3
we outline the question on the bistability of interacting wires , and we ilustrate this question by an analytical solution in the simplest case of parallel wires . in section 4 ,
conditions of the bistability are investigated numerically .
this section contains also some examples of the hysteresis loops of various bistable systems , including the case with the applied tensile stress .
final conclusions close the text .
in order to capture the dependence of the switching field vs the tensile stress the axial hysteresis loop of as - cast wire of the nominal composition @xmath10 , the diameter @xmath11 @xmath12 and the length of @xmath13 @xmath14 was measured by means of the conventional induction method @xcite .
the frequency of the external sine - like field was equal to @xmath15 @xmath16 and the amplitude of was set to @xmath17 @xmath18 .
one end of a wire was fixed to the sample holder , while to the other one a mechanical loading was attached in order to apply the additional tensile stress @xmath19 during the magnetic measurement .
the mechanical loading was being changed from zero to @xmath20 @xmath21 . obtained values of the switching field @xmath22
are shown in fig . 1 .
the wires considered here are iron - based straight pieces of amorphous alloy , @xmath23=10 cm long , with diameter of 2@xmath24=120 micrometers .
their magnetization is @xmath25=5.6@xmath26 a / m .
this kind of wires are well worked out in the literature @xcite .
the magnetic pole at each end contains the magnetic charge @xmath27= @xmath280.0063 am .
the switching ( coercive ) field is about 10 a / m .
suppose that a center of such a wire is placed at the coordination center , and the wire is parallel to oz - axis .
in the surrounding space , there are planes where the vertical component of the stray field is equal to the applied field , equal in this case to the switching field .
if a system of two wires is to be bistable , the second wire can not go through such a plane .
if it does , the domain wall in the second wire is stopped . in the ( r - z ) plane ,
the condition that the field created by one magnetic pole plus the external field @xmath29 cancel with the field created by another magnetic pole is @xmath30 where @xmath31 for @xmath29=0 , the equation can be untangled . expressing all lengths in units of @xmath32 , what is a half of the wire length , and
after some simple manipulation we get the equation @xmath33 one of the consequences of this condition is that parallel wires of exactly the same length and very close to each other cease their bistability if they are mutually shifted along their length .
let us consider the case when they are not shifted ; then they form edges of a rectangle .
the axial component of the stray field created at an end of one wire at distance @xmath34 from the closer end of another wire is @xmath35 where @xmath36 is the interwire distance .
this component is maximal at the point @xmath34 where @xmath37 , and its value at the maximum varies with @xmath36 approximately as @xmath38 .
if @xmath39 , the contribution to the stray field from other wire end is negligible .
however , this evaluation relies on an assumption that the remagnetization starts at the point at the wire where the stray field from another wire has a maximum .
this assumption remains not justified .
also , the obtained values of the interaction field much excess the observed value , which is of order of 10 a / m for the distance @xmath36 of 1 mm @xcite .
this can mean , that in fact the switching starts at smaller value of @xmath34 , i.e. closer to the wire end .
anyway , the evaluation @xmath40 seems to better reflect the experimental data of ref .
@xcite , than the formula used in ref .
@xcite for microwires @xmath41 at least for small interwire distance @xmath36 .
the latter formula can be derived as the interaction between the opposite ends of the wires .
we should add that the authors of ref .
@xcite used is to test the stray field dependence on the wire length .
the stress dependence of the point @xmath34 where the remagnetization starts could explain the observed variation of the interaction field with stress @xcite .
the values of the interaction field , observed in this experiment , are as large as 500 a / m .
this order of magnitude can be reproduced by the formula @xmath38 , given above .
then , the observed difference between the conventional and the cold - drawn wires can be discussed in terms of the position of the point , where the remagnetization starts .
in figs . 2 - 8 we show numerical solutions of the same problem for various mutual orientations of the wires .
the value of the applied field is taken as to get the remagnetization .
this means that the effective field at one end of the wire is equal to the switching field . here
again , the question is : will the domain wall reach the other wire end ? marked areas in the figures give the values of the parameters , where the answer is `` no '' .
let us assume that the magnetic field is along the oz axis .
the spatial configurations are : wire a along the field , wire b in the same plane xz forms an angle @xmath42 ( fig .
2 ) ; one wire along the field , another perpendicular , also in the plane xz but with y different by 2 mm ( fig .
3 ) ; two wires in the parallel planes xz with distance 2 mm one from another , both wires form angles @xmath43 with the field ( fig .
4 ) ; two wires in the same plane xz , one perpendicular to the field , another forms angle @xmath44 with the former , as clock hands ( fig .
5 ) ; two wires in the same plane xz , one parallel to the field , another forms angle @xmath44 with the former , as clock hands ( fig .
6 ) ; two wires in the same plane xz form the same angle with the field , rotating as bird wings ( fig .
7 ) ; three wires along three edges of a tetrahedron , form the same angles with the field ( fig . 8) . in the case shown in fig .
6 we include also the tensile stress , as large as to enhance the switching field @xmath45 from 10 to 15 a / m .
this is shown to change remarkably the area where the bistability is absent .
we also show some parameters of the obtained hysteresis loops .
the width of the horizontal part of the loops which is responsible for the wire - wire interaction @xcite , is denoted as @xmath46 .
the right - shift of the loop center along the field axis is denoted as @xmath47 , and the width of the loop - as @xmath48 . in several cases ,
the results reflect obvious properties of the systems .
for example , for the wires almost perpendicular to the applied field , the hysteresis loop must be very wide .
we note that when the wires are not parallel to the applied field , the measured and calculated @xmath46 ceases its simple interpretation as the interaction field , but depends also on the orientation of wires with respect to the external field .
to summarize main shortcomings of our approach : _
i ) _ the wire - wire interaction is approximated with an assumption on the uniform wire magnetization , _ ii ) _ our considerations are limited to the case of strict bistability , where the domain wall moves till the end of the wire at the same external field as it started to move . as it was remarked above , the former approximation can be justified if the distance between wires is much larger ( at least one order of magnitude ) than the wire diameter .
the second limitation excludes many cases which can be of interest . in these cases the dynamics of domain walls depends on the field amplitude and frequency @xcite , and the numerical solution of the equation of motion of the domain wall seems to be the only proper method .
even with the drawbacks listed above , the results of the model calculations point out that spatial configurations of bistable wires offer a rich variety of hysteresis loops .
the parameters of the loops can be controlled by the modification of mutual positions of the wires , the angles formed by the wires and the applied magnetic field and of the applied tensile stress .
the obtained hysteresis loop reveal stable states , which remain until the external field is enhanced above some critical values .
then , these states encode the information on previous conditions applied to the wire .
+ k. k. and p. g. are grateful to julian gonzlez and arcady zhukov for helpful discussions and kind hospitality .
00 m. vzquez and a. hernando , j. phys .
d * 29 * ( 1996 ) 939 .
m. vzquez , physica b * 299 * ( 2001 ) 302 .
k. mohri , t. uchiyama , l. p. shen , c. m. cai and l. v. panina , j. magn .
magn . mater .
* 249 * ( 2002 ) 351 .
r. hertel , j. magn .
magn . mater .
* 249 * ( 2002 ) 251 .
h. forster , t. schrefl , w. scholz , d. suess , v. tsiantos and j. fidler , j. magn .
magn . mater .
* 249 * ( 2002 ) 181 .
j. velzquez , k. r. pirota and m. vzquez , ieee trans . magn .
* 39 * ( 2003 ) 3049 .
r. varga , k. l. garcia , m. vzquez and p. vojtanik , phys .
* 94 * ( 2005 ) 17201 .
a. kaczanowski and k. kuakowski , micr . eng .
* 81 * ( 2005 ) 317 .
j. velzquez , c. garcia , m. vzquez and a. hernando , phys .
b * 54 * ( 1996 ) 9903 . l. c. sampaio , e. h. c. p. sinnecker , g. r. c. cernicchiaro , m. knobel , m. vazquez and m. velazquez , phys .
b * 61 * ( 2000 ) 8976 .
t. a. savas , m. farhoud , h. i. smith , m. hwang and c. a. ross , j. appl .
* 85 * ( 1999 ) 6160 .
r. p. cowburn and m. e. welland , science * 287 * ( 2000 ) 1466 .
a. mitra and m. vzquez , j. phys .
* 23 * ( 1990 ) 228 .
m. vzquez , j. gonzlez and a. hernando , j. magn .
magn . mater .
* 53 * ( 1986 ) 323 .
chen , n. m. dempsey , a. hernando and m. vzquez , j. phys .
* 28 * ( 1995 ) 1022 . c. gomez - polo , m. vzquez and d
chen , appl .
. lett . * 62 * ( 1993 ) 108 .
p. gawroski , z. zhukov , j. m. blanco , j. gonzlez and k. kuakowski , j. magn .
* 290 - 291 * ( 2005 ) 595 .
g. krupiska , a. zhukov , j. gonzlez and k. kuakowski , comp .
* 36 * ( 2006 ) 268 . | long - range magnetostatic interaction between wires strongly depends on their spatial position .
this interaction , combined with applied tensile stress , influences the hysteresis loop of the system of wires through the stress dependence of their coercive fields . as a result
, we obtain a set of stable magnetic states of the system , dependent on the applied field , applied stress and mutual positions of the wires .
these states can be used to encode the system history .
* stable states of systems of bistable magnetostrictive wires against applied field , applied stress and spatial geometry * + p. gawroski@xmath0 , a. chizhik@xmath1 , j. m. blanco@xmath2 and k. kuakowski@xmath3 + _ @xmath4 faculty of physics and applied computer science , agh university of science and technology , al .
mickiewicza 30 , 30 - 059 krakw , poland + @xmath5 departamento fisica de materiales , facultad de quimica , upv , 1072 , 20080 san sebastian , spain + @xmath2 departamento fisica aplicada i , eupds , upv / ehu , plaza europa , 1 , 20018 san sebastian , spain + @xmath6e - mail : [email protected] + @xmath7e - mail : [email protected] + @xmath8e - mail : [email protected] + _ _ pacs numbers : _
75.50.kj , 75.60.ej , 75.80.+q _ keywords : _ micromagnetism , amorphous wires , hysteresis , magnetostatics |
FILE - In this Feb. 4, 2015 file photo, Supreme Court Justice Ruth Bader Ginsburg speaks at Georgetown University Law Center in Washington. Ginsburg’s public criticism of Donald Trump is dividing legal... (Associated Press)
WASHINGTON (AP) — The Latest on Campaign 2016 ahead of the Republican and Democratic National conventions (all times EDT):
12:05 a.m.
Former House Speaker Newt Gingrich is responding to Thursday night's truck attack in France by arguing for the expulsion from the U.S. of any Muslim who believes in Sharia law.
Gingrich is being considered as a possible running mate by presumptive Republican presidential nominee Donald Trump.
The former Georgia congressman said on Fox News Channel's "Hannity" that the U.S. "should frankly test every person here who is of a Muslim background, and if they believe in Sharia, they should be deported. Sharia is incompatible with Western civilization."
Gingrich is calling the attack in Nice, France, which killed at least 80 people, "the fault of Western elites who lack the guts to do what is right, to do what is necessary, and to tell us the truth, and that starts with Barack Obama."
__
11:45 p.m.
Hillary Clinton says Americans stand "in strong solidarity with the people of France," after a truck attack in Nice, France, adding, "We will not be intimidated."
A truck carrying weapons and hand grenades plowed through a group of people celebrating Bastille Day in Nice late Thursday, killing at least 80 people.
The Democratic presidential candidate says the U.S. and France will never let terrorists undermine democratic values. She says the "cowardly attack only strengthens our commitment to our alliance and to defeating terrorism around the world."
__
10 p.m.
Republican presidential candidate Donald Trump says in the aftermath of a deadly truck attack in France that if he's elected president he would ask Congress for a declaration of war on the Islamic State.
In an interview with Fox News Channel's "The O'Reilly Factor," Trump says, "This is war." He spoke after a truck carrying weapons and hand grenades drove onto a sidewalk in Nice, France, and plowed through people celebrating Bastille Day, killing at least 77 people.
Trump says to fight the Islamic State, which he calls a "cancer," NATO should be used "for a purpose."
It was not immediately clear Thursday night who was behind the attack.
In a separate interview on Fox, Democratic candidate Hillary Clinton says the U.S. needs to "stand strongly" with France and strengthen our alliances, including with NATO, to ferret out terrorism and prevent future attacks. Clinton says she would intensify efforts to put together a more effective coalition against terrorism.
__
9:50 p.m.
A committee at the Republican National Convention has defeated an effort by conservatives who want to let delegates vote for any presidential candidate they'd like.
Thursday's vote by the convention's rules committee was a major blow to forces trying to derail Donald Trump's nomination at the GOP gathering next week.
The 112-member panel is dominated by top party officials and delegates loyal to Trump.
The proposal's author is Colorado delegate Kendal Unruh. She has said she'll try to force a vote on her proposal in the full convention next week — a vote she'll also be likely to lose.
__
9:05 p.m.
Tim Tebow won't be at the Republican National Convention after all.
The former football star was to be among the biggest names at next week's GOP convention in Cleveland.
But he says in a Thursday night Facebook post that his attendance was simply a rumor. He commented roughly 12 hours after Donald Trump's campaign announced his status as a convention speaker.
Tebow says: "I just got back from the Philippines, and I wake up this morning to find out that I'm speaking at the Republican National Convention. It's amazing how fast rumors fly. And that's exactly what it is, a rumor."
Tebow says he'd do "anything for America." But that won't include appearing in Cleveland next week on Trump's behalf.
Tebow says he'll focus his time instead on helping children through his foundation.
8:55 p.m.
A committee holding early meetings at the Republican National Convention has decided to vote sooner than expected on an uphill drive by opponents of Donald Trump to "unbind" delegates so they can vote for any presidential candidate they'd like.
The convention rules committee had planned to hold a vote on that proposal Friday. But working late into the evening, the panel voted to hold that roll call Thursday evening.
The proposal by Colorado delegate Kendal Unruh would let delegates vote their conscience and back any contender, not the one they were committed to by state primaries and caucuses.
When the full convention holds its meetings next week, Unruh and other conservatives hope that change would let the gathering block Trump's nomination to be GOP presidential candidate. But they are unlikely to prevail.
__
7:35 p.m.
Donald Trump is insisting that he has yet to settle on a running mate.
The presumptive Republican presidential nominee says in an interview on Fox News Channel, "I haven't made a final, final decision."
Indiana Gov. Mike Pence has emerged as a late favorite for the job, but Trump advisers caution that the businessman had not made a final decision and could still change his mind.
Trump tells Fox that Pence has done a wonderful job in Indiana, but adds that fellow finalists Chris Christie and Newt Gingrich as "fantastic" people.
Trump has canceled a Friday news conference where he planned to make public his VP choice, citing the truck attack in France that has killed dozens.
Trump says that it's "crazy what's going on" and says, "We have to get awfully tough and we have to get very, very smart."
___
7:13 p.m.
Donald Trump says on Twitter that he is delaying the announcement of his running mate following the deadly truck attack in France.
After a day of speculation about who might join Trump atop the Republican Party's presidential ticket, Trump tweets on Thursday night: "In light of the horrible attack in Nice, France, I have postponed tomorrow's news conference concerning my Vice Presidential announcement."
Trump had been scheduled to unveil his pick at an 11 a.m. news conference at a hotel in midtown Manhattan.
Late Thursday, a truck drive onto the sidewalk and plowed through a crowd of revelers who'd been gathered to watch Bastille Day fireworks in Nice, France. Authorities say dozens of people are dead.
___
6:20 p.m.
Talks aimed at averting some battles at the Republican National Convention between GOP leaders and conservatives have broken down.
That increases the chances of a confrontation between the two sides next week when the full convention meets in Cleveland.
The longshot effort by conservatives to "unbind" delegates and let them back any candidate they want was not addressed by the talks. That issue is seemingly headed toward a fight next week.
Leaders of the Republican National Committee spent hours Thursday meeting with conservatives who are pushing populist changes in party rules that would weaken leadership powers. The two sides could not reach agreement.
Conservatives hope to force votes on their proposals by the full convention. Party leaders say they'll be able to defeat them, but they'd hoped to avoid battles on national television.
__
4:40 p.m.
Sen. Ted Cruz is refusing to condemn a rebellion against Donald Trump at the Republican National Convention as the fiery Texas conservative weighs his political future against the prospect of a national Republican embarrassment.
Cruz's continued public silence, as his loyalists actively plotted to undermine Trump on Thursday, irked Trump allies and Republican leaders alike, all eager to avoid a public spectacle when the four-day gathering formally begins on Monday.
Yet having accepted a speaking slot on the main stage, there are signs the 45-year-old senator is willing to cooperate with Trump's campaign — privately, at least — even as he works to sustain his popularity among anti-Trump conservatives.
___
2:52 p.m.
Hillary Clinton is assuring Senate Democrats that she will pick a "very qualified" vice presidential candidate during their weekly luncheon on Capitol Hill.
The former secretary of state was asked during the private luncheon who she would choose as her running mate, prompting a roar from the audience and promises that they wouldn't tell anyone.
Clinton says after the luncheon that she had a "great conversation" with them and talked about ways to bring economic opportunity to the nation and "build a strong Democratic party."
Lawmakers say Clinton's former Democratic opponent, Bernie Sanders, received applause at the lunch. The meeting also included potential Clinton running mates like Tim Kaine of Virginia, Elizabeth Warren of Massachusetts and Sherrod Brown of Ohio.
___
2:37 p.m.
Newt Gingrich says he still has not heard from Donald Trump about his running mate selection.
In a brief interview with The Associated Press, Gingrich said he was still expecting to hear from the Republican nominee Thursday. Gingrich told the AP earlier in the day that he had expected to receive word from Trump sometime after 1 p.m.
____
2:29 p.m.
Former House Speaker Newt Gingrich says that Donald Trump's impending vice presidential decision ultimately comes down to whether he wants a fellow "pirate" or a "relatively stable, more normal person."
Gingrich is one of the three finalists the presumptive GOP nominee is considering for his running mate.
He's speaking on Facebook live about the intricacies of the vetting process and sharing his thoughts on the two other finalists: Indiana Gov. Mike Pence and New Jersey Gov. Chris Christie.
Gingrich suggests that he has yet to hear from Trump about his decision.
He says, "We'll find out what Donald Trump decides to do."
___
1:25 p.m.
Hillary Clinton has arrived at a weekly luncheon with Senate Democrats where she is expected to brief them on her presidential campaign.
The presumptive Democratic nominee said Thursday, "it's great to be back here in the Senate." She received loud applause from the Democratic members.
Clinton was joined at the lunch by some of her former colleagues as well as potential vice presidential choices, including Tim Kaine of Virginia, Elizabeth Warren of Massachusetts and Sherrod Brown of Ohio.
Her onetime Democratic presidential rival Bernie Sanders was also at the lunch. He endorsed Clinton in New Hampshire on Tuesday.
Clinton was scheduled to campaign in Virginia with Kaine later in the day.
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12:00 p.m.
House Speaker Paul Ryan says Indiana Gov. Mike Pence would be a good pick for Donald Trump's vice president.
Ryan says it's no secret he's a big fan of Pence's and holds him in very high regard.
Ryan tells reporters Thursday: "I hope that he picks a good movement conservative. Clearly Mike is one of those."
The Wisconsin Republican says he doesn't know what Trump will do, and "I hope he makes a good pick and clearly that would be a good one."
Trump's vice presidential announcement is expected soon with the Republican National Convention getting under way in Cleveland next week.
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11:55 a.m
Hillary Clinton is vowing to expand upon President Barack Obama's executive actions on immigration despite the Supreme Court's recent deadlocked ruling.
Clinton says in a speech at the League of United Latin American Citizens' national convention that she will put a comprehensive immigration bill before Congress in her first 100 days of office.
She says the high court did not "actually rule on the substance of the case" and it's within the authority of the president to temporarily stop the deportation for millions of people living in the U.S. illegally.
Clinton says she will create a "simple, straight forward system" in which people with sympathetic cases or a history of serving their communities can make their case and become eligible for deferred action.
The Democratic presidential candidate was also meeting Thursday with Senate Democrats and campaigning with Virginia Sen. Tim Kaine, a possible vice presidential pick.
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11:52 a.m.
Newt Gingrich says he is hosting a "Facebook Live" event Thursday afternoon to discuss the Republican "vice presidential picks and the VP selection process."
Gingrich is one of the finalists to join Donald Trump on the November ticket. Earlier Thursday, the former House speaker told The Associated Press that he expects to hear from Trump shortly after 1 p.m. about whether he's been chosen. Gingrich's Facebook event is scheduled for 2 p.m.
Gingrich, who has been active on the social media venue, hosted a Facebook Live event with Trump earlier this month.
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11:18 a.m.
Indiana Gov. Mike Pence quickly exited a planned speaking event in Indianapolis shortly after releasing details about a new economic development initiative.
The Republican governor is considered a top contender to become Donald Trump's vice president pick. Pence and his entourage swiftly exited the building and climbed into a waiting motorcade.
His office and his re-election campaign have not released details of any other planned events after several days of repeated public appearances.
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11:12 a.m.
Senior U.S. national security officials say they are worried about the potential for violence at the Republican National Convention to be held in Cleveland next week.
During congressional testimony Thursday, Homeland Security Secretary Jeh (jay) Johnson says he's concerned that demonstrations outside the convention hall may get out of hand.
Johnson says he will be inspecting the security around the convention hall during a visit Friday. He says he says similar concerns about the Democratic convention to be held in Philadelphia. He'll be visiting that site next week.
Johnson tells the House Homeland Security Committee there will be 4,000 U.S. government security personnel in Cleveland.
FBI Director James Comey says anytime there is a large, national event there is concern that radical people and groups may be drawn to it.
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10:56 a.m.
A pivotal committee of delegates at the Republican National Convention has abruptly taken a recess of several hours, just as it was beginning to consider rules changes proposed by conservatives and foes of presumptive presidential nominee Donald Trump.
Some delegates said the Trump campaign and top GOP officials were trying to see if they could strike a compromise with conservatives trying to let delegates back any candidate they want and offering other rules changes.
A leader of those conservatives is Ken Cuccinelli, who was a campaign adviser to Texas Sen. Ted Cruz's now abandoned presidential campaign. GOP Chairman Reince Priebus and top Trump campaign officials were also in the convention center.
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10:24 a.m.
Newt Gingrich says he expects to hear from Donald Trump about his vice presidential decision as early as Thursday afternoon.
In a brief interview with The Associated Press, Gingrich says he expects the decision sometime after 1pm. He says he had not heard from the Trump campaign Thursday morning.
Gingrich, the former House speaker, is among Trump's top choices, along with Indiana Gov. Mike Pence and New Jersey Gov. Chris Christie.
Gingrich praised Trump for running a "very fair, open process" and said he looked forward to the businessman's decision.
Trump and his running mate will make their first joint appearance Friday in New York.
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10:16 a.m.
Supreme Court Justice Ruth Bader Ginsburg says she regrets her "ill-advised" public criticism of Donald Trump.
Ginsburg says in a statement issued by the court on Thursday that judges should avoid commenting on a candidate for public office. She promises to be more circumspect in the future.
Ginsburg told The Associated Press last week that she did not want to think about the prospect of Trump winning the presidency. She escalated her criticism in subsequent media interviews.
She came under attack for her comments in recent days, leading to Thursday's statement.
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8:40 a.m.
Donald Trump's campaign and party leaders seem poised to defeat GOP renegades trying to derail the billionaire's presidential nomination. But it's unclear they'll prevail before the dispute flares into a potentially angry and embarrassing floor fight next week.
The two sides on Thursday were beginning what could be a two-day faceoff at early meetings of the convention's rules committee. That panel's initial votes are expected to demonstrate how firmly Trump and GOP Chairman Reince Priebus control the convention, which meets in full next week. ||||| Washington (CNN) President Barack Obama on Friday issued a thinly veiled rebuke of former House Speaker Newt Gingrich's call for the U.S. to test every person with a Muslim background to see if they believe in Sharia law and deport those who do.
Addressing the terror attack in Nice, France, that left more than 80 people dead, Obama didn't mention Gingrich by name, but there was little doubt who he was calling out.
"In the wake of last night's attacks, we've heard more suggestions that all Muslims in America be targeted, tested for their beliefs, some deported or jailed," Obama said in remarks from the White House. "And the very suggestion is repugnant and an affront to everything that we stand for as Americans."
Obama's implicit critique of Gingrich was a part of broader point he made Friday in response to the Nice attack, which he called "sickening."
"It's been a difficult several weeks in the United States, but the divide that exists is not between races and ethnicities and religions," Obama said. "And those impulses, when we do not speak out against them and build institutions to protect people from those impulses, they can take over. They can be unleashed, so all of us have responsibilities, not just a few."
Obama said the fight against terrorists will be won when the United States "stays true to our values."
Earlier Friday, White House Press Secretary Josh Earnest was asked directly about the former speaker's comments.
"It sounds like he may need to consult his copy of the pocket Constitution as well," Earnest said at a White House press briefing, adding that "proposals like that, rhetoric like that, is un-American by its very definition."
Gingrich's original comments came on Thursday night during an interview on Fox News, hours after a truck rampaged through a Bastille Day celebration in Nice.
"Let me be as blunt and direct as I can be: Western civilization is in a war. We should frankly test every person here who is of a Muslim background, and if they believe in Sharia, they should be deported," Gingrich said in an interview with Fox News' Sean Hannity. "Sharia is incompatible with Western civilization. Modern Muslims who have given up Sharia, glad to have them as citizens. Perfectly happy to have them next door."
Gingrich defended those comments Friday during an appearance on Facebook Live but acknowledged that "deportation is impossible" with American citizens.
"It's not appropriate under the Constitution, and historically, we've always said if you fought against the United States, that the correct answers were basically jail as opposed to deportation," he said. "I think we have to talk through what should be the right way of handling people who are here but are not citizens."
Newt Gingrinch speaks on February 27, 2015.
Gingrich also used the Facebook Live appearance to try to assuage Muslims living in the U.S.
"If you are a practicing Muslim and you believe deeply in your faith, but you're also loyal to the United States and you believe in the Constitution, you should have your rights totally, completely protected within the Constitution," Gingrich said. "You should have nothing to fear. Your children should have nothing to fear."
"This is not about targeting a particular religion or targeting people who practice in a particular way," he added. "This is about looking at particular characteristics that we have learned painfully, time after time, involve killing people, involve attacks on our civilization."
Muslims and experts on Islam quickly criticized Gingrich's initial comments.
Apparently a lot of ppl who know nothing abt Islam are now experts on Islam and sharia, telling Muslims what their religion *actually* says — Shadi Hamid (@shadihamid) July 15, 2016
"Apparently a lot of people who know nothing about Islam are now experts on Islam and sharia, telling Muslims what their religion actually says," tweeted Shadi Hamid, a senior fellow at the Brookings Institution.
While Sharia is often defined as "Islamic law," there is no single book of jurisprudence followed by all 1.6 billion Muslims. In fact, there are varying interpretations and legal opinions -- called fatwas -- most of which concern rituals, family matters and personal spirituality. In that way, Sharia is similar to Jewish law, and Israel is among the countries that allow Sharia courts, noted The Atlantic's Jeffrey Goldberg.
Omar Suleiman, a popular Muslim scholar in Dallas, took a defiant stance toward Gingrich's comments.
"Newt Gingrich, I'll make your job easier for you: I believe in every single tenet of my faith," Suleiman wrote in a Facebook post . "Because of that, I speak against extremists overseas and extremists like you and the fraud running for President. You can try to deport me now."
Gingrich calls for monitoring mosques
During the interview on Thursday, Hannity asked Gingrich how "you possibly ascertain whether or not that person really wants assimilation, really wants a new life, or whether or not they want to expand that caliphate, which is what we're at war against?"
"The first step is you have to ask them the questions," Gingrich responded. "The second step is you have to monitor what they're doing on the Internet. The third step is, let me be very clear, you have to monitor the mosques. I mean, if you're not prepared to monitor the mosques, this whole thing is a joke. Where do you think the primary source of recruitment is? Where do you think the primary place of indoctrination is? You've got to look at the madrassas -- if you're a school which is teaching Sharia, you want to expel it from the country."
The comments by Gingrich -- who was a finalist to be Donald Trump's running mate before the real estate mogul tapped Indiana Gov. Mike Pence on Thursday -- are similar to ones made by Trump himself last fall , when he called for surveillance of "certain mosques" to counter terrorist threats.
Gingrich also said Thursday that calling Islam a "religion of peace" is "bologna."
"It's not that Islamists are necessarily evil, but they're not necessarily a religion of peace," Gingrich said.
Gingrich then turned his focus to President Barack Obama, citing many leading Democrats' argument for stricter gun regulation laws after the Orlando terror attack , where 49 individuals where shot and killed inside a nightclub.
"I fully expect by tomorrow morning that President Obama will have rediscovered his left-wing roots and will give a press conference in which he'll explain that the problem is too many trucks," Gingrich said. "If only we had truck regulation, then we wouldn't have problems like Nice because it is trucks that are dangerous. I mean that's the exact analog to Orlando and just tells you how nuts the left wing in America is."
Trump's campaign manager Paul Manafort was asked to respond to Gingrich's comments on CNN's "New Day," but said he didn't know what Gingrich's comments were and what the context was.
"The point is the country's got serious problems dealing with terrorism," Manafort said.
Gingrich was also asked about Trump's decision to select Pence as his running mate. The former House speaker acknowledged it appeared the Indiana governor was the choice, but said, "I've not been officially told." | – Newt Gingrich managed to out-Trump Donald Trump in the wake of Thursday night's horrific attack in Nice, calling for nothing less than the ideological testing of all Muslims in the US and the expulsion of those who don't pass muster. "Let me be as blunt and direct as I can be. Western civilization is in a war. We should frankly test every person here who is of a Muslim background, and if they believe in Sharia, they should be deported," Gingrich told Fox News' Sean Hannity, per CNN. "Sharia is incompatible with Western civilization. Modern Muslims who have given up Sharia, glad to have them as citizens." Gingrich added that Muslims should also have their mosques and online activities monitored. Gingrich went on to blame the attack on President Obama, saying it was "the fault of Western elites who lack the guts to do what is right, to do what is necessary, and to tell us the truth, and that starts with Barack Obama," the AP reports. He predicted that Obama will give a press conference "in which he'll explain that the problem is too many trucks." Gingrich, who had been in the running to become Trump's VP choice, told Hannity that it now appears that Indiana Gov. Mike Pence has gotten the nod, "but I've not been officially told yet." Trump, who spoke to Fox's Bill O'Reilly, didn't go as far as Gingrich, but he said as president, he would ask Congress to declare war on global terrorism, reports the New York Times. "If you look at it, this is war. Coming from all different parts," he said. "And frankly it's war, and we're dealing with people without uniforms." (Trump has delayed his VP announcement, which had been scheduled for Friday morning.) |
WASHINGTON — A few hours before President Obama offered his historic endorsement of same-sex marriage on Wednesday, Vice President Joseph R. Biden Jr. apologized to the president in the Oval Office for forcing Mr. Obama’s hand by airing his own views three days earlier, several people briefed on the exchange said on Thursday.
Mr. Biden declared in an interview on Sunday that he was “absolutely comfortable” with same-sex marriage, a position that went considerably further than the president’s “evolving” views on the matter and scrambled the White House’s carefully laid plans for confronting one of the most sensitive social issues in the election.
Mr. Obama, in an interview with ABC News, said the vice president had gotten “a little bit over his skis” but had done so “out of generosity of spirit.” The president bore Mr. Biden no lingering ill will, according to several officials, though the episode enraged Mr. Obama’s senior advisers in the White House and on the campaign.
It was easily the biggest instance of crossed wires between the garrulous vice president and his more button-down boss, in an administration that has been marked by occasional eruptions by Mr. Biden. And its effect was magnified both because it involved a fraught social issue and because it came just as the general election campaign is heating up.
People who know both men said they did not believe that Mr. Biden had an ulterior motive in pre-empting the president, despite the fact that he has not ruled out running for president himself in 2016. Indeed, several gay rights activists said, whatever affection Mr. Biden’s candor might have won him with gay voters, he would still lag behind other potential Democratic candidates like Gov. Andrew M. Cuomo of New York or Secretary of State Hillary Rodham Clinton, who are both seen as champions of the gay community.
Mr. Biden has said nothing publicly since his remarks on the NBC program “Meet the Press.” But he has told staff members at the White House that he regrets putting the president in an awkward spot, several officials said. These officials declined to characterize his precise remarks to Mr. Obama, or Mr. Obama’s response.
The White House had planned for the president to endorse same-sex marriage as soon as next Monday, when he was scheduled to give an interview to the ABC program “The View.” Instead, in the wake of Mr. Biden’s interview, the president’s aides hastily scheduled an interview Wednesday with Robin Roberts of ABC News. ||||| Vice President Biden apologized to President Obama on Wednesday morning for saying he supported same-sex marriage before the administration had planned to, White House officials said.
Obama said he understood, saying he knew Biden had spoken from the heart, according to the officials.
“The President has been the leader on this issue from day one and the Vice President never intended to distract from that,” Kendra Barkoff, the vice president’s press secretary, said Thursday in a statement.
The apology came the first time Biden and Obama spoke after Sunday, when NBC’s “Meet the Press” broadcast an interview with Biden in which he said he was “comfortable” with men marrying men and women marrying women.
At the time, Obama had yet to publicly endorse same-sex marriage.
On Wednesday, President Obama told ABC’s Robin Roberts that Biden “probably got a little bit over his skis” on the issue.
Administration officials insisted that Obama had reached his own decision earlier this year but said that he told only a small circle of people, numbering roughly six or seven, and made clear to advisers that he wanted to announce his support before the Democratic National Convention in Charlotte, scheduled for the first week of September.
The timeline was sped up, however, by Biden’s comments, the officials said in a briefing with reporters Wednesday at the White House, speaking on the condition that they not be named or quoted.
White House officials learned about Biden’s statement soon after the news program was recorded Friday. They said Obama then decided he wanted to make his position known.
In the interview, Biden said, “Look. I am vice president of the United States of America. The president sets the policy. I am absolutely comfortable with the fact that men marrying men, women marrying women and heterosexual men and women marrying are entitled to the same exact rights, all the civil rights, all the civil liberties. And quite frankly, I don’t see much of a distinction beyond that.”
Immediately after its airing Sunday morning, a Biden spokesman said that the vice president “was saying what the president has said previously — that committed and loving same-sex couples deserve the same rights and protections enjoyed by all Americans, and that we oppose any effort to roll back those rights.
“That’s why we stopped defending the constitutionality of Section 3 of the Defense of Marriage Act in legal challenges and support legislation to repeal it,” the aide said. “Beyond that, the vice president was expressing that he too is evolving on the issue, after meeting so many committed couples and families in this country.”
Obama senior adviser David Axelrod said via Twitter shortly after Biden spoke: “What VP said-that all married couples should have exactly the same legal rights-is precisely POTUS’s position.” | – Skeptics may think Joe Biden's public comments on gay marriage were carefully orchestrated, but the White House insists it was just Joe being Joe. In fact, Biden apologized to the president the first time the two spoke afterward, reports the New York Times and Washington Post. (Both cite anonymous administration officials.) The apology came yesterday morning, hours before Obama offered his own public support for same-sex marriage. Biden reportedly told the president that he didn't intend to force Obama's hand on the matter. In the Post's telling, Obama responded that he had no hard feelings because Biden gave an honest and heartfelt response to a question. In his subsequent ABC interview, Obama said Biden had "probably gotten a little over his skis" on the matter. In any event, it seems to have worked out fine for the vice president. |
A team of Dallas doctors has achieved a significant milestone in an experimental surgery that is hoped to one day dramatically change the lives of women born with no uterus and other fertility issues.
In late November, a baby boy delivered at Baylor University Medical Center became the first in the nation to be born to a mom whose reproductive organs had been implanted from another woman’s body.
Only a handful of teams globally have ever attempted the controversial uterine transplant surgery. In 2016, Baylor became the first in the U.S. to try it, using organs donated by women who are not deceased.
Eight women have received a donated uterus in the Baylor program to date. So far, one has achieved the ultimate outcome: a baby. That infant, delivered via C-section last month, is now known as “Baby Number Nine,” as only eight other babies in the world have been born as a result of the novel procedure.
It’s a major milestone that follows a years-long journey by a determined North Texas team, said transplant surgeon and lead investigator Dr. Giuliano Testa. ||||| For the first time in the United States, a woman who was born without a uterus gave birth to a baby. The landmark birth took place at Baylor University Medical Center at Dallas, a part of Baylor Scott & White, TIME reports exclusively.
“We’ve been preparing for this moment for a very long time,” says Dr. Liza Johannesson, an ob-gyn and uterus transplant surgeon at Baylor. “I think everyone had tears in their eyes when the baby came out. I did for sure.” The woman and her husband asked that their identity not be revealed in order to protect their privacy
The birth took place at Baylor — the first birth in the hospital’s ongoing uterus transplant clinical trial. Women who participate in the trial have what’s called absolute uterine factor infertility (AUI), which means their uterus is nonfunctioning or nonexistent. Most of the women in the trial have a condition called Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome — and have lived their entire lives under the assumption that they would never be able to be pregnant or give birth to a baby. The procedure could also work for women with other medical issues, such as certain cancers.
“We do transplants all day long,” says Dr. Giuliano Testa, the leader of the uterus transplant clinical trial at Baylor, and surgical chief of abdominal transplant for Baylor Annette C. and Harold C. Simmons Transplant Institute. “This is not the same thing. I totally underestimated what this type of transplant does for these women. What I’ve learned emotionally, I do not have the words to describe.”
The birth was a scheduled Caesarean section, and most members of the multidisciplinary clinical trial team were present. The baby was delivered healthy and screaming. “I’ve delivered a lot of babies, but this one was special,” says Dr. Robert T. Gunby Jr., the obstetrician and gynecologist who delivered the baby. “When I started my career we didn’t even have sonograms. Now we are putting in uteruses from someone else and getting a baby.”
The moment Dr. Gunby first held up the baby was emotional for many members of the medical team. “Outside my own children, this is the most excited I’ve ever been about any baby being born,” says Dr. Gregory J. McKenna, a transplant surgeon at Baylor. “I just started to cry.”
A donor’s gift
Taylor Siler, 36, a registered nurse in the Dallas area, donated her uterus to the woman who recently gave birth. Siler wasn’t always certain she wanted to have children, but she says deciding to get pregnant was one of her best decisions. “Once they lay that baby in your arms,” Siler says. “Your life changes forever.”
Siler, who has two boys aged 6 and 4, came across a news segment about Baylor’s uterus transplant program. She and her husband had already decided they were not going to have any more children, and she wanted to offer someone else a shot at motherhood. “I have family members who struggled to have babies, and it’s not fair,” says Siler. “I just think that if we can give more people that option, that’s an awesome thing.”
Siler went through extensive screening about both her physical and mental health before getting approval for the trial. Participating required surgery and about 12 weeks of recovery. Baylor says it typically takes about five hours for the wombs to be removed from the living donors, and another five to transplant.
Though she did not know the woman who received her uterus, Siler and the recipient exchanged letters on the day of the surgery, and the recipient sent Siler another letter to let her know when she was pregnant. Baylor informed Siler this week that the woman had given birth. “I’ve just been crying and getting teary thinking about it, “ says Siler, who had not yet met the new mother when she spoke to TIME. “I think about her every day and I probably will for the rest of my life.”
How a uterus transplant works
The women in the clinical trial are transplanted with a uterus from either a living or deceased donor. The woman who gave birth received her transplant from Siler, who was a so-called “altruistic” living donor: a stranger who volunteered to donate her uterus to a woman without one. So far, Baylor says they’ve had over 70 women express interest in donating their uterus.
Baylor will complete a total of 10 uterus transplants as part of its first trial. So far the hospital has completed eight. At least three have failed. The hospital has confirmed to Time that there is another woman in the trial who is pregnant, using a living donor uterus.
The baby's father rests his hand on the child. Baylor University Medical Center at Dallas.
Baylor’s uterus transplant program is one of a handful to launch in the United States in recent years, and it’s the first to use both living and deceased donors. Successful uterus transplants from live donors have taken place in Sweden — a medical team at Sahlgrenska University Hospital in Gothenburg pioneered the first uterus transplant trial that resulted in eight births. This first birth at Baylor is the first to replicate that success.
Dr. Johannesson was part of the original uterus transplant team and has since moved to Texas in order to work on the Baylor program. “We were very proud of the first birth in Sweden,” she says. “But this birth is what’s going to make the field grow, because this is the first time this has been replicated anywhere else. This step is equally, if not even more, important.”
The recipients in the clinical trial are between the ages of 20 to 35, and the donors must be between ages 30 to 60. “When you donate a kidney, you do it to help someone live longer and get off dialysis,” says Dr. Testa. “For these women, they are donating an experience.”
Most of the women in the trial have moved to the Dallas area in order to undergo the procedures and the many follow up visits and tests. Once the women in the trial are transplanted with the uterus, they wait to recover and achieve menstruation, usually about four weeks from transplant. Women whose transplant is successful can then attempt in vitro fertilization (IVF). (The women in the trial have functioning ovaries that are not attached to their wombs, which is why IVF is required to get pregnant.)
Uterus transplants are expensive, with some estimates putting the cost at up to $500,000. Like other infertility treatments, it’s very rare that an insurance company would cover the procedure, which is largely viewed as elective. Baylor covered the cost of the first 10 transplants in the clinical trial, but the medical team is now seeking funding—largely through donations from institutions and private donors—in order to continue. The team says many more transplants need to be done before it could be provided as a standard treatment. “The reality is that it’s going to be very difficult for many women to afford this,” says Testa.
The baby's feet in the father's hands. Baylor University Medical Center at Dallas
Renewed hope
Last year, when Baylor began the trial, Testa told TIME that the study would not be deemed a success unless the transplants resulted in a birth. Compared to other transplants that he regularly performs, like liver or kidneys, where surgeons know within minutes if the organ is working, Testa says waiting through the pregnancy after uterus transplant can feel excruciating.
“I was already nervous when my wife was pregnant, and this felt worse, like it was my pregnancy,” says Testa.
Since the procedure requires an otherwise healthy person to undergo multiple surgeries and take powerful medication, women in uterus transplant trials often say they experience comments from people asking why they don’t opt for surrogacy or adoption. “A lot of people underestimate the impact that infertility can have on a person’s wellbeing,” says Johannesson. “It can have such a profound impact.”
Baylor says they do not view uterus transplants as a replacement for other approaches like adoption or surrogacy, but as another option for women and their partners.
Baylor will continue to follow the health of the baby as part of the study. The goal is for the birth to mark the beginning of a new field of infertility treatment research, rather than be an outlier.
“For the girl who is getting the [infertility] diagnosis now, it’s not hopeless,” says Kristin Posey Wallis, a uterine transplant nurse at Baylor who works closely with women and their donors. “There’s hope.”
Contact us at [email protected]. ||||| (Photo: Baylor Scott & White)
DALLAS - It's a boy! And a medical breakthrough in the United States.
Baylor Scott & White announced Friday that the first baby was born in the United States to a mother who received a uterus transplant at a Dallas hospital.
"The delivery at Baylor University Medical Center at Dallas is a breakthrough in medical research and a major milestone in a landmark clinical trial," said Baylor Scott & White in a video posted to their Twitter account.
Back in January of 2016, Baylor University Medical Center at Dallas told WFAA they planned to implant wombs into 10 women. Each of the women had absolute uterine factor infertility (AUFI), which means they had a non-existent or non-functioning uterus.
BREAKING: Baylor University Medical Center at Dallas Announces First Baby Born in United States to Mother Who Received #UterusTransplant. pic.twitter.com/Lp0RJmuRvj — Baylor Scott & White (@bswhealth) December 1, 2017
The first uterus transplant trial took place in Sweden, where there were five live births. Their first successful birth was in September 2014.
The Cleveland Clinic was the first to begin a clinical trial in the United States to help women give birth through uterus transplants. However, the nation's first such transplant failed due to a fungal infection that compromised blood flow to the uterus.
The surgery was performed on a 26-year-old patient in late February of 2016 but doctors were forced to remove the transplanted uterus a little more than two weeks later.
Over a nine-day period in September of 2016, Baylor performed four uterine transplants. Baylor doctors were assisted by a Swedish medical team during the procedures. Three of the transplants failed but the fourth led to the first uterus transplant birth in the U.S.
© 2018 WFAA-TV | – For the first time ever in the US, a woman born without a uterus has given birth, Time reports. The baby boy was delivered via a planned Caesarean section in late November at Baylor University Medical Center at Dallas; the historic birth was announced Friday. "We've been preparing for this moment for a very long time," uterus transplant surgeon Dr. Liza Johannesson says. Baylor has completed eight uterus transplants as part of an ongoing clinical trial, but at least three have failed. The unidentified woman was the first to give birth with a transplanted uterus in the US and only the ninth woman in the world to do so, according to the Dallas Morning News. Multiple surgeons at Baylor report crying during the birth. “It gives hope to women who didn’t feel like they had hope,” says Dr. Colin Koon, a member of the transplant team. The women in the clinical trial have absolute uterine factor infertility, which means their uterus doesn't work or isn't there, and many had grown up without hope of giving birth. Doctors say the uterus transplant procedure could also one day help women with other medical complications, such as cancer-related hysterectomies, give birth. “I have family members who struggled to have babies, and it’s not fair,” 36-year-old Taylor Siler tells Time. “I just think that if we can give more people that option, that’s an awesome thing.” Siler donated the uterus that made last month's historic birth possible. The first attempt at a uterus transplant birth in the US failed due to a fungal infection last year at the Cleveland Clinic, WFAA reports. |
autosomal dominant polycystic kidney disease ( adpkd ) is a common inherited disease that affects approximately 1 in 1,000 individuals .
the disease 's main clinical manifestations are bilateral renal cyst formation and hypertension , and the half of these patients reach end stage renal failure by the age of 60 yr ( 1 ) .
adpkd is genetically heterogeneous and most of the afflicted families have mutations of either pkd1 on chromosome 16 ( -85% ) or pkd2 on chromosome 4 ( -15% ) ( 2 - 3 ) .
pkd1 encodes polycystin-1 ( pc-1 ) , which is an integral membrane protein of 4,302 amino acids with an expected molecular mass of 462 kda ( 4,5 ) .
pc-1 is widely expressed in the renal tubular epithelium and it is thought to be a cell - cell / matrix receptor molecule at the cell surface . pc-1 and pc-2 may heterodimerize to form a pc complex and this could function as the same signaling pathway ( 6,7 ) . however , there are controversies about the pc-1 expression and function when using different antibodies to study them .
the large size and the low expression of pc-1 have made the study of pc-1 very difficult .
there are also some doubts as to the specificity of the pc-1 antibodies ( 8,9 ) . as an initial approach towards studying adpkd and to obtain more insight into pc-1 expression , we have carried out immunoblot and immunochemical analyses of the pc-1 expression in the tubular cells of fetal , adult and adpkd kidneys .
we used human embryonic kidney ( hek ) 293 cells and renal proximal tubular epithelial cellsr ( rptecs ) for performing immunoblottting .
the cells were grown to 70 - 90% confluence and they were then lysed in phosphate buffered saline that contained 0.5% nonidet p-40 .
a large amount of protein ( -400 g each ) was separated on 4% sds - page gel with or without boiling .
the membranes were blocked with 5% nonfat dry milk for 1 hr and they were next incubated with primary antibodies diluted at 1:500 .
we used two pc-1 antibodies ; c-20 ( santa cruz , sc-10372 , santa cruz , ca , u.s.a . ) was used as the c - terminal antibody and p-15 ( santa cruz , sc-10307 , santa cruz , ca , u.s.a . ) was used as the n - terminal antibody .
after washing , the membranes were incubated for 1 hr at room temperature with the peroxidase - labeled secondary antibody ( anti - goat igg - hrp , santa cruz ) at 1:500 dilution .
the membrane - bound antibodies were detected by using the enhanced chemiluminescence detection system ( amersham biosciences , bucks , u.k . ) .
normal fetal kidney was obtained from autopsy ( gestation age : 20 weeks , weight : 305 grams ) after spontaneous abortion .
adult kidneys were obtained from renal tumor nephrectomy patients ( a male 58 yr old and a male 63 yr old ) .
the autosomal dominant polycystic kidneys were obtained from pkd1 patients ( a male 53 yr old and a male 46 yr old ) who had the typical clinical manifestations during transplant nephrectomy .
all the tissues were embedded in optimal cutting temperature compound ( sakura tissue tek , torrance , ca , u.s.a . ) and stored at -70 until further use .
cryosections 5 m thick were cut , and the tissues were fixed in acetone at -20 for 10 min and then washed with phosphate - buffered saline . after blocking the endogenous peroxidase activity , the primary antibodies ( c-20 and p-15 ) were diluted to 1:100 and the sections were incubated for 1 hr with them at room temperature .
after washing , the sections were incubated for 45 min with the secondary antibody ( bionylated anti - goat ig , dako , glostrup , denmark ) .
the reaction was developed with 3-amino-9-ethylcarbazol ( aec , red stain ) or with 3,3'diaminobenzidine ( dab , brown stain ) .
we used human embryonic kidney ( hek ) 293 cells and renal proximal tubular epithelial cellsr ( rptecs ) for performing immunoblottting .
the cells were grown to 70 - 90% confluence and they were then lysed in phosphate buffered saline that contained 0.5% nonidet p-40 .
a large amount of protein ( -400 g each ) was separated on 4% sds - page gel with or without boiling .
the membranes were blocked with 5% nonfat dry milk for 1 hr and they were next incubated with primary antibodies diluted at 1:500 .
we used two pc-1 antibodies ; c-20 ( santa cruz , sc-10372 , santa cruz , ca , u.s.a . ) was used as the c - terminal antibody and p-15 ( santa cruz , sc-10307 , santa cruz , ca , u.s.a . ) was used as the n - terminal antibody .
after washing , the membranes were incubated for 1 hr at room temperature with the peroxidase - labeled secondary antibody ( anti - goat igg - hrp , santa cruz ) at 1:500 dilution .
the membrane - bound antibodies were detected by using the enhanced chemiluminescence detection system ( amersham biosciences , bucks , u.k . ) .
normal fetal kidney was obtained from autopsy ( gestation age : 20 weeks , weight : 305 grams ) after spontaneous abortion .
adult kidneys were obtained from renal tumor nephrectomy patients ( a male 58 yr old and a male 63 yr old ) .
the autosomal dominant polycystic kidneys were obtained from pkd1 patients ( a male 53 yr old and a male 46 yr old ) who had the typical clinical manifestations during transplant nephrectomy .
all the tissues were embedded in optimal cutting temperature compound ( sakura tissue tek , torrance , ca , u.s.a . ) and stored at -70 until further use .
cryosections 5 m thick were cut , and the tissues were fixed in acetone at -20 for 10 min and then washed with phosphate - buffered saline . after blocking the endogenous peroxidase activity , the primary antibodies ( c-20 and p-15 ) were diluted to 1:100 and the sections were incubated for 1 hr with them at room temperature .
after washing , the sections were incubated for 45 min with the secondary antibody ( bionylated anti - goat ig , dako , glostrup , denmark ) .
the reaction was developed with 3-amino-9-ethylcarbazol ( aec , red stain ) or with 3,3'diaminobenzidine ( dab , brown stain ) .
we confirmed that the c-20 antibody was sensitive for detecting pc-1 by performing immunoprecipitation ( 10 ) , and we confirmed the pc-1 expression in the hek 293 cells and in the rptec lysates ( fig .
1 ) . however , this was technically difficult because of the large size of the pc-1 molecule and its faint expression level . in the fetal and adult kidneys ,
the patterns of expression were diffuse and cytoplasmic at the proximal tubules , distal tubules and collecting ducts .
the expression in the fetal kidney was more prominent in the proximal tubules ( fig .
the pc-1 proteins were weakly expressed in the tubular or cystlining epithelial cells , as compared to that of the fetal and adult kidneys .
we confirmed that the c-20 antibody was sensitive for detecting pc-1 by performing immunoprecipitation ( 10 ) , and we confirmed the pc-1 expression in the hek 293 cells and in the rptec lysates ( fig .
however , this was technically difficult because of the large size of the pc-1 molecule and its faint expression level .
in the fetal and adult kidneys , the staining was restricted to tubular epithelial cells cytoplasm ( fig .
the patterns of expression were diffuse and cytoplasmic at the proximal tubules , distal tubules and collecting ducts .
the expression in the fetal kidney was more prominent in the proximal tubules ( fig .
the pc-1 proteins were weakly expressed in the tubular or cystlining epithelial cells , as compared to that of the fetal and adult kidneys .
the identification of pc-1 , which is the major gene mutated protein seen in adpkd , is a major step for discovering the pathogenesis in this common hereditary disease .
however , there 's been some controversy about the pc-1 expression when using different antibodies to detect it .
the difficulties for studying pc-1 are due to the antibody specificity and the low levels of pc-1 expression in cells and tissues .
moreover , two thirds of the pkd1 gene is duplicated on chromosome 16 and there are at least three homologus genes .
our study showed that pc-1 may be very weakly expressed in the renal tubular cells , as observed by immunoblotting , and it is widely expressed in the fetal and adult renal tubular epithelial cells cytoplasm , as observed by immunochemistry . before this study
, we confirmed that c-20 antibody was sensitive to detect the pkd-1 c - terminal by performing immunoprecipitation ( 10 ) . to verify the specificity of the immunohistochemical staining , we performed immunoblot analysis of the kidney cells ( hek 293 cells and rptecs ) , the kidney tissues ( fetal and adults ) and the adpkd tissues .
we were unable to detect the pc-1 band in the kidney tissues and the adpkd tissues .
this is suggested that the pc-1 is either not expressed at detectable levels in normal and adpkd kidneys , or it is lost during sample preparation .
however , we were able to detect low levels of pc-1 in the kidney cells . according to the previous reports ( 8,9 ) ,
immunoblotting of pc-1 was technically difficult because of the large size of the pc-1 molecule and the faint level of expression .
a number of published papers have described the pc-1 expression in normal renal and cystic tissue .
11 ) have reported that in the early fetal kidney , pc-1 was localized to the plasma membranes of the ureteric buds and the s - shaped bodies . however , in the late fetal kidney and in the adpkd kidney , the majority of pc-1 staining was intracellular .
they detected several bands in the fetal kidney and no bands were detected in the adult kidney by immunoblotting .
they detected about a 400 kda pc-1 band in the fetal and adult mouse and human kidneys .
pc-1 was noted to be localized at the plasma membrane and pc-1 expression was seen in most ( -90% ) of the adpkd cysts .
ong et al . ( 14 ) reported that in adult pkd1 tissue , the majority of cysts ( -80% ) showed pc-1 expression , although pc-1 staining was absent in a variable , but significant minority of the cysts ( -20% ) .
leeuwen et al . ( 15 ) found that the mutant pkd1 mice that had a reduced pkd1 gene expression showed polycystic kidney disease .
they generated a novel mouse model with a hypomorphic pkd1 allele , and the pathologic features of this mouse were similar to the human adpkd phenotype .
recently , roitbak et al . ( 16 ) have reported that pc-1 formed a complex with e - cadherin and -catenin at both the cell membrane and intracellularly .
enhanced phosphorylation of pc-1 changed its subcellular localization and its ability to form protein complexes .
second , the pc-1 is expressed in the tubular epithelium and in the adpkd cyst epithelium .
third , the subcellular localization of pc-1 is mainly on the cell surface membrane and it may be changed in some conditions .
our results showed similar patterns of pc-1 expression for the fetal , adult and adpkd kidneys , but our immunohistochmical study showed a cytoplasmic staining pattern of pc-1 .
however , in the hek 293 cells grown to 80% confluency , we found that the pc-1 was localized on the cell surface membrane by performing immunofluorescent staining with using c-20 antibody ( 10 ) .
. the epitope recognized by these antibodies may be not the full length , but rather , they are only a fraction of the pc-1 .
pc-1 is the pkd 1 gene translated protein , and it is a 4,302 amino acids glycoprotein with an expected molecular mass of 460 kda .
experimental studies have shown that pc-1 is a highly glycosylated 520 kda polypeptide that is present in the plasma membrane ( 6,7 ) . by performing amino acid sequence homology analysis , pc-1 was found to be a membrane receptor that is capable of binding and interacting with ligands .
recent research have shown that pc-1 is also localized to the renal cilia and to the protein - mediated mechanosensation in the primary cilium of the kidney ( 17,18 ) in summary , we have found by performing immunoblotting that pc-1 is expressed at a very low level in the renal tubular cells .
however , pc-1 is widely expressed in the fetal and adult renal tubular epithelial cells cytoplasm , as was noted upon performing the immunohistochemistry . in the adpkd kidney ,
the pc-1 proteins were heterogenously and weakly expressed in the tubular or cyst lining epithelial cells . a reduced pc-1 expression
our data suggests that the development of kidney may regulate the expression of pc-1 , and the altered pc-1 expression may contribute to cyst formation seen in adpkd . | the mutation of the pkd1 gene causes autosomal dominant polycystic kidney disease ( adpkd ) , and the pkd1 gene encodes polycystin-1 ( pc-1 ) .
pc-1 is thought to be a cell - cell / matrix adhesion receptor molecule at the cell surface that is widely expressed in the kidney . however , there are controversies about the role of pc-1 protein and its expression when using different antibodies to detect it .
we used two pc-1 antibodies ; c-20 ( santa cruz , sc-10372 ) as the c - terminal antibody , and p-15 ( santa cruz , sc-10307 ) as the n - terminal antibody .
we evaluated the pc-1 expression by performing immunoblotting on the human embryonic kidney ( hek ) 293 cells and the renal proximal tubular epithelial cell ( rptec ) lysates .
we characterized the expression of pc-1 in the fetal , adult and polycystic kidneys tissues by performing immunohistochemistry .
we confirmed the pc-1 expression in the hek 293 cells and the rptec lysates , but the expression was very low .
the pc-1 proteins were diffusely expressed in the tubular epithelial cells cytoplasm in the fetal and adult kidneys , and the pc-1 expression was more prominent in the proximal tubules of the fetal kidney . in the adpkd kidney , the pc-1 proteins were heterogenously and weakly expressed in the tubular or cyst lining epithelial cells .
our data suggests that the development of the kidney may regulate the expression of pc-1 , and an altered pc-1 expression may contribute to cyst formation in adpkd . |
gastric volvulus is defined as the rotation of the stomach or part of the stomach by more than 180 , which creates a closed loop obstruction .
it can lead to ulceration , perforation , hemorrhage , or ischemia of the incarcerated stomach .
quick detection and prompt surgical correction are the mainstays of therapy for acute gastric volvulus .
the traditional treatment of gastric volvulus includes laparotomy , gastric detorsion , and gastric fixation .
if the volvulus is secondary to a diaphragmatic defect , the defect should be corrected .
the present report describes the case of a 50-year - old patient with acute primary gastric volvulus who was treated by laparoscopic reduction with percutaneous endoscopic gastrostomy ( peg ) .
while this approach has been employed for chronic gastric volvulus , to our knowledge , it has not been used for the treatment of acute gastric volvulus .
a 50-year - old man with a medical history of subdural hematoma 8 years previously recently reported the sudden onset of pain in the epigastric area .
he visited the local hospital and was checked by simple abdominal x - rays , abdominal computed tomography ( ct ) and gastroscopy .
he was diagnosed with acute gastric volvulus and was transferred to our hospital for an emergency operation .
his vital signs were as follows : temperature , 36.9 ; heart rate , 70/min ; blood pressure , 170/90 mmhg ; and respiration , 16/min . on physical examination ,
both the abdominal erect and supine x - ray views reveal the distention and air - fluid levels in the stomach ( fig .
2a depicts the twisted axis : the stomach was rotated along the axis that joins the mid and lesser curvatures ( mesentero - axial volvulus ) .
2b , arrow indicates the esophagus and gastroesophageal junction , and arrow shows that the body portion is superior to the fundus area .
2c shows that the gastric low body is located below the diaphragm and is connected to the duodenum .
since this is one of the symptoms and a sign of gastric strangulation , an emergency operation was scheduled . after administering a general anesthetic ,
the surgeon stood to the right of the patient and the first assistant stood opposite the surgeon .
the umbilical camera port was established by using an open technique . after establishing a pneumoperitoneum ,
blood stains in the greater omentum were detected along with a mass - like twisted stomach below the diaphragm ( fig .
the reduction of the gastric volvulus was performed by placing traction on the greater omentum with two atraumatic bowel graspers .
3d ) . an endoscopic image of the peg after its insertion is shown in fig .
an upper gastrointestinal ( gi ) contrast study was performed on the third postoperative day and complete reduction of the stomach was confirmed without any evidence of obstruction ( fig .
the patient was put on a diet on the fourth postoperative day and was discharged on the sixth .
he was readmitted for the removal of the peg 2 months after the initial operation . after fasting beginning at midnight
five months after his initial operation , the abdominal scars had almost completely disappeared ( fig .
after administering a general anesthetic , the patient was placed in the inverted y position .
the surgeon stood to the right of the patient and the first assistant stood opposite the surgeon .
the umbilical camera port was established by using an open technique . after establishing a pneumoperitoneum ,
blood stains in the greater omentum were detected along with a mass - like twisted stomach below the diaphragm ( fig .
the reduction of the gastric volvulus was performed by placing traction on the greater omentum with two atraumatic bowel graspers .
3d ) . an endoscopic image of the peg after its insertion is shown in fig .
an upper gastrointestinal ( gi ) contrast study was performed on the third postoperative day and complete reduction of the stomach was confirmed without any evidence of obstruction ( fig .
the patient was put on a diet on the fourth postoperative day and was discharged on the sixth .
he was readmitted for the removal of the peg 2 months after the initial operation . after fasting beginning at midnight ,
five months after his initial operation , the abdominal scars had almost completely disappeared ( fig .
although rare , acute gastric volvulus is a gi condition that has catastrophic complications if it is not treated promptly .
although endoscopic reduction can be achieved in patients with chronic forms of gastric volvulus , it is not recommended for initial therapy in an acute setting , except for the treatment of high risk patients .
the first reported case of gastric volvulus was by berti in 1866 after he performed an autopsy on a 60-year - old woman .
berg is credited with the first successful operative reduction of a gastric volvulus in 1896 . in 1904
, borchardt described the classic triad of severe epigastric pain and distention , vomiting , followed by violent retching without the ability to vomit , and difficulty or inability to pass through a nasogastric tube .
gastric volvulus occurs when the stomach rotates along its longitudinal axis ( organo - axial volvulus ) , or along the axis joining the midlesser and greater curvatures ( mesentero - axial volvulus ) .
one - third of gastric volvulus cases are caused by congenitally lax gastrocolic ligaments or are acquired .
two - thirds of gastric volvulus cases are secondary to paraesophageal hernia or a diaphragmatic defect .
the signs and symptoms of gastric volvulus depend upon the rapidity of onset , the degree of rotation , and the amount of obstruction .
clinically , gastric volvulus may present either as an acute abdominal emergency or as a chronic recurrent problem .
vascular compromise that leads to gangrene occurs in 5 - 28% of patients who present with acute volvulus .
patients with gastric infarction may present with gi hemorrhage , acute cardiopulmonary distress , or shock .
the reported overall mortality rates of acute gastric volvulus range from 15% to 20% , while those for chronic gastric volvulus range from 0% to 13% .
strangulation is considered the chief cause of this high death rate . in the present case ,
we believe that the acute gastric volvulus caused abrupt stomach distension and was one of the causes of short gastric artery tearing .
supporting this is that most of the blood and the hematoma were observed near the spleen .
endoscopic decompression and reduction has also been used to treat acute gastric volvulus in high risk patients .
eckhauser and ferroon introduced dual percutaneous gastrostomy for gastric fixation in chronic volvulus in 1985 . in most cases of acute gastric volvulus ,
the goals of surgery are reduction of the volvulus , gastic fixation to prevent recurrence , and repair of any predisposing factors .
emergent laparoscopic reduction and anterior gastropexy was first reported in 2003 . a laparoscopic approach to treatment
several recent reports describe a laparoscopic approach to both acute and chronic gastric volvulus with good results .
laparoscopic surgery is now a safe and acceptable approach for treating gastric volvulus , with minimal morbidity and shorter hospital stays . in summary ,
the case of a 50-year - old patient with acute primary gastric volvulus who was treated successfully by laparoscopic reduction and peg is reported here .
laparoscopic reduction combined with peg is a feasible and safe method for not only chronic gastric volvulus , but also for acute gastric volvulus . | acute gastric volvulus requires emergency surgery , and a laparoscopic approach for both acute and chronic gastric volvulus was reported recently to give good results . the case of a 50-year - old patient with acute primary gastric volvulus who was treated by laparoscopic reduction and percutaneous endoscopic gastrostomy
is described here .
this approach seems to be feasible and safe for not only chronic gastric volvulus , but also acute gastric volvulus . |
since the discovery of the first optical afterglow @xcite associated with a gamma - ray burst ( grb ) , several robotic telescopes have been developed to perform rapid follow - up observations of grb afterglows .
fast robotic follow - ups are now possible because of the improved localization of grbs provided by current gamma - ray satellites ( _ hete - ii _ ,
_ integral _ , _ swift _ , _ interplanetary network _ ) ; real - time grb alerts are received from these satellites through the grb coordinates network ( gcn ) @xcite within a few seconds of the grb onset and provide positions with typical uncertainties of a few arcmin .
observations within minutes of the grb can be crucial to determine the properties of the close circumburst environment , potentially providing clues to the nature of the progenitor . to date
, only a few grbs have measurements of their optical afterglow starting as early as a few minutes after the grb : 990123 , 021004 , 021211 , 030418 , 041006 , 041218 , 041219a , 050319 , 050401 , 050502a , 050525 , 050712 , 050713a , 050730 , 050801 , 050802 , 050820a , 050824 , 050904 , 050908 , 050922c , 051021a ( october 2005 ) .
figure [ fig : lc ] shows the early afterglow light curves for all of them within the first day after the burst .
for each grb we collected unfiltered , @xmath5 , @xmath6 and @xmath7 observations .
the liverpool telescope ( lt ) , owned and operated by liverpool john moores university ( ljmu ) , has a 2-m diameter primary mirror , altitude - azimuth design , final focal ratio f/10 . it was designed and built by telescope technologies limited , with the robotic control system and instrumentation being provided by the ljmu astrophysics research institute @xcite .
it is situated at the observatorio del roque de los muchachos , on the canary island la palma . due to the fully opening enclosure and to the fast slew rate of 2@xmath8/s ,
the telescope can start observations within 13 min of the receipt of the gcn alert notice .
lt has five instrument ports : four folded and one straight - through , selected by a deployable rotating mirror in the ag box within 30 s. the telescope is equipped with the _ ratcam _ optical ccd camera , and with the _ supircam _ 12.5 @xmath9 m camera . a _
prototype spectrograph _ and an optical polarimeter ( _ ringo _ ) based on a design by @xcite are expected to be operating later in 2006 .
a higher resolution , higher sensitivity and generally more capable spectrograph ( _ frodospec _ ) is being developed for deployment in 2007 .
table [ tab : instr ] reports the main characteristics of each instrument .
in addition to the grb follow - up program , which has high priority on the lt , the robotic control @xcite and automated scheduler @xcite allow the lt to conduct an optimized science program of observations of time variable sources over a wide range of timescales from target of opportunity ( e.g. novae , supernovae , anomalies in gravitational lenses ) to longer - term monitoring ( e.g. agn , variable stars ) , when no grb observations are required .
ll optical ccd camera - & 2048@xmath102048 pixels , 0.135``/pixel , fov [email protected] , + & 8 filter selections ( u , g , r , i , z , b , v , h@xmath11 , nd2.0 ) + & - from lt first light , july 2003 + 1 - 2.5 micron camera - & 256@xmath10256 pixels , 0.4''/pixel , fov [email protected] , + ( with imperial college ) & z , j , h , k filters - from late 2005 + - & 49 , 1.7 " fibres , 512@xmath10512 pixels , r=1000 ; + ( with university of manchester ) & 3500 @xmath4 @xmath12 @xmath4 7000 - from 2006 + optical polarimeter & ring polarimeter based on the design of @xcite + & - from 2006 + integral field & r=4000 , 8000 ; + double beam spectrograph - & 4000 @xmath4 @xmath12 @xmath4 9500 - from 2007 + ( with university of southampton ) & +
when a grb fulfills all the requirements to be observed with the lt , the grb over - ride mode is triggered . the grb program takes control of the telescope and triggers the so - called `` detection mode '' ( sec .
[ sec : dm ] ) , during which a small number of sloan @xmath0-band short - exposure images are taken .
these images are then transferred to the lt proxy machine , a network - attached on - site computer . the automatic lt grb pipeline , called _ liverpool telescope transient rapid analysis pipeline _
( hereafter _ lt - trap _ ) , is then invoked to process , analyze and interpret these images and returns a value to indicate whether any variable optical transient ( ot ) candidate has been identified .
the result of this analysis drives the automatic selection of the subsequent observing mode as follows : * identification of a fading ot with @xmath13 @xmath14 multi - color imaging mode ( sec . [ sec : mcim ] ) ; * identification of a fading ot with @xmath15 @xmath14 polarimetry mode ( 2006)/spectroscopy mode ( 2007 ) ( sec .
[ sec : sm ] ) ; * no identification of an ot @xmath14 riz mode ( sec . [ sec : riz ] ) . figure [ fig : strategy ] shows a diagram of the overall observing strategy when the grb over - ride mode is triggered .
the grb target of opportunity control agent ( grb toca ) is a shell script that is invoked in response to a grb alert being received at lt via a socket connection .
this script uses the toca of the lt robotic control system ( rcs ) to take control of the telescope , provided that the grb position is observable and other requirements are fulfilled , e.g. : * the positional error circle is sufficiently small ( error radius @xmath16 arcmin ) ; * altitude above horizon is @xmath17 ; * the position does not match any known x - ray catalog source ; * in the case of _ swift _ alert , the image significance should not be low ( to - date , no real grb was found to have the low image significance flag raised ) ; * none of the five known soft - gamma ray repeaters ( sgrs ) , sgr 1900 + 14 , sgr 1806 - 20 , sgr 1627 - 41 , sgr 0526 - 66 and sgr 1801 - 23 , lies in the error circle . as noted above , the average delay between the arrival time of the gcn alert and the start time of observations ranges between 1 and 3 min . in the case of an sgr lying in the error circle ,
the grb toca triggers a sgr follow - up ir observation with the _ supircam _ according to the strategy defined in an sgr follow - up approved proposal led by the lt grb group . currently , the automatic sgr follow - up program is still under test , so the presence of an sgr in the error circle merely invalidates the grb follow - up observation .
when all of the above conditions are fulfilled , the grb toca repoints the telescope , then triggers the acquisition of the first set of images scheduled in the detection mode ( following commissioning of ringo ( 2006 ) , the detection mode exposures will be preceded by an initial short polarimetric exposure ) .
the _ lt - trap _ is then invoked to analyze these images and consequently choose the most suitable observing strategy ( see sec .
[ sec : dm ] for a detailed description ) .
the ringo exposure will be analyzed offline at a later time and plays no part in real - time decision making ; the motivations of this choice are explained in section [ sec : pm ] .
the grb toca and the _ lt - trap _ communicate through the noticeboard , which is a plain text file continuously updated until the end of observations .
this not only reports in real time a detailed chronological sequence of all the actions and results acquired through , following technical conventions , but also represents a useful real - time human - readable interface for the users responsible for monitoring the on - going observation sequence .
the dm consists of a sequence of two sets of three 10-s exposure images taken in @xmath0 .
these are the first images of the grb field acquired by the telescope .
once each set has been acquired and copied to the proxy machine , the grb toca invokes the grb astrometric fit script on each image .
after object extraction and comparison with standard catalogs , an ot candidates list is extracted for each set of three images .
these ot candidates are then processed by the grb variability script , which aims to identify sources common to each image set and evaluate possible variability .
finally the dm reports the best ot candidate ( if any ) out of the two merged lists .
this shell is responsible for fitting the astrometry and identifying possible ot candidates .
below we report the detailed sequence of operations performed on each single image by this script : 1 . source extraction using a customized version of _ sextractor 2.3.2 _
@xcite is performed ; if the number of sources extracted is lower than 3 , it does not attempt to fit the astrometry .
in contrast , if more than 20 sources are extracted , only the 20 brightest ones are used in the astrometric fit procedure .
a @xmath18 portion of the usno b1.0 astrometric catalog @xcite , centered on the centroid position of the grb , is retrieved from a complete copy stored locally on the lt proxy machine . in case of problems accessing the local catalog ,
the script attempts to retrieve it through the on - line interface of the usno b1.0 .
3 . the retrieved catalog image is then cropped to match exactly the field of view of the lt .
optical extinction for the field is determined from the dust maps by @xcite .
an astrometric fit is performed using an adapted version of the wcs @xcite tool _
imwcs 3.5.3 _ @xcite .
the fit is considered to have failed if either the number of matched sources is lower than 3 or if the fraction of matched sources is lower than 50% .
if the astrometric fit is successful , the pixel - to - sky coordinates transformation is performed through the wcs tool _
xy2sky 3.5.7 _ @xcite , based on the result of the astrometric fit . a typical value for the fit residual is @xmath190.3 arcsec . 7 .
in case of astrometric fit failure , all the image sources are considered in principle as potential ot candidates and they are reported in the ot candidates files , although with a lower confidence level ( see below ) .
the pixel - to - sky coordinate transformation is performed assuming the nominal pointing ( typical accuracy currently of @xmath191020 arcsec , with a target on completion of commissioning of the telescope of 2 arcsec ) . in this case
, the script ends at this point .
selection of the ot candidates : if the astrometric fit is successful , all the image sources are cross - checked with the catalog stars and classified according to a set of criteria .
a 17-bit variable is assigned to each source and describes its properties .
each image source not associated with any usno
b1.0 star is assigned 50 points . each bit of the 17-bit variable
is assigned a given number of points to be added to the initial 50 points credit ( see table [ tab : grbpipe ] ) .
9 . selected classes of non - associated image sources
are a priori excluded from the candidate search . among them , the objects with clearly non - stellar psfs are probably the most important ( e.g. cosmic ray events , reflections , failed deblending ) . a mean stellar psf is defined on each image based on real - time associated objects median statistics .
each selected ot candidate is assigned a confidence level directly related to the total number of points accrued . 11 .
each selected ot candidate is cross - checked with the on - line gsc2.3 and 2mass catalogs and its confidence level is adjusted accordingly ( see table [ tab : grbpipe ] ) . when the astrometric fit is successful , magnitudes are estimated from the usno
b1.0 stars that have been matched .
we use as zero point the median value of the offset needed to have a match between the instrumental magnitude and the @xmath5 magnitude reported in the usno
b1.0 catalog .
the error associated with the zero - point is then evaluated in terms of the clipped ( @xmath20 ) root mean square deviation with respect to the usno b1.0 .
rrllr 1 & 1 & the extracted magnitude is biased by bright neighbours & astrometric & 0 + 2 & 2 & the object has been deblended & astrometric & -10 + 3 & 4 & at least one pixel is saturated ( @xmath21 60000 counts ) & astrometric & 0 + 4 & 8 & object truncated ( close to the image border ) & astrometric & -50 + 5 & 16 & aperture data incomplete or corrupted & astrometric & -10 + 6 & 32 & isophotal data incomplete or corrupted & astrometric & -10 + 7 & 64 & memory overflow occurred during deblending & astrometric & -10 + 8 & 128 & memory overflow during extraction & astrometric & -20 + 9 & 256 & was nt possible to check gsc and/or 2mass & astrometric & -20 + 10 & 512 & a gsc2.3 object lies close ( @xmath4 2 arcsec ) & astrometric & -50 + 11 & 1024 & a 2mass object lies close ( @xmath4 2 arcsec ) & astrometric & -30 + 12 & 2048 & a bright usno star ( r@xmath413 ) is close ( @xmath450px ) & astrometric & -20 + 13 & 4096 & astrometric fit failed assuming nominal pointing & astrometric & -50 + 14 & 8192 & object detected in at least 2 ot lists & variability & + 30 + 15 & 16384 & object not detected in at least 1 ot list & variability & -10 + 16 & 32768 & variability detected over 23 images & variability & + 50 + 17 & 65536 & astrometric fit warning & variability & 0 + after the _ lt - trap _ script described above has run on the three images , the three resulting ot candidates files , each reporting a list of potential ots found in each single image , are cross - checked through the so - called `` variability script '' .
this shell script is invoked by the grb toca and aims to recognize objects common to each of the ot candidates files , as well as to evaluate possible significant magnitude variations between the three images .
this variation is evaluated by performing a @xmath22 test on the zero hypothesis that there is no significant variation . if the three values of magnitude are found to be consistent with a constant value with a significance lower than 1% , the variability bit is raised ( table [ tab : grbpipe ] ) .
each ot candidate confidence level is finally adjusted on the basis of the variability results ( bit number 16 , see table [ tab : grbpipe ] ) .
table [ tab : grbpipe ] reports the meaning of each bit of the 17-bit variable assigned to each ot candidate and the points assigned to each flag .
the confidence level is evaluated by dividing the total points by 100 : when this ratio is @xmath23 , the confidence level is set to zero ; when the ratio is @xmath24 , the level is assigned 1.0 ( highest confidence level possible ) . the final threshold on the confidence level for an ot candidate to trigger the multi - color imaging mode ( sec . [ sec : mcim ] )
is currently set at 0.7 . in case of more than one ot candidate with confidence level above the threshold
, the grb toca accepts that with the highest value .
if the ambiguity is still unresolved , it assumes the first on the list .
however , all the information regarding the other candidates is reported in the noticeboard file as well as in the product files .
the meaning of each single bit described in table [ tab : grbpipe ] is self - explanatory , apart from the last bit , called `` astrometric fit warning '' , which requires an explanation .
this bit is raised whenever at least one of the three images has a failure in the astrometric fit and at least another one has a successful astrometric fit . in this case , the identification of the same object in different images is performed on the basis of pixel coordinates , while the sky coordinates are taken from the image with the correct astrometry .
however , so far this case has turned out to be very rare : either all or none of them are successfully astrometrically fitted .
for this reason , the current points assigned to this bit are zero . to test the sensitivity of the script
, we simulated on real images an ot fading according to a power law , @xmath25 ( where @xmath26 is the grb onset time ) .
the script detected significant variability for @xmath2712 , for objects at least as bright as @xmath281617 , provided that the dm is triggered at @xmath29 s. also , in the case of grb 050502a , where the dm was triggered at @xmath30 s , the _ lt - trap _ detected significant variability : the magnitudes evaluated by the _ lt - trap _ were for the three dm images : @xmath31,@xmath32 and @xmath33 .
the corresponding @xmath22 test gave the following result : @xmath34 , with a significance of @xmath35 .
it must be pointed out that the systematic error affecting the usno
b1.0 magnitudes is around 0.3 mag ; furthermore , it is not possible to correct for color terms at this stage .
however , this is not relevant , as the purpose of the script is to establish relative variations , regardless of the absolute values . to account for possible variations in the zero point
, the script adopts the following approach : it calculates the root mean square deviation of the three zero points and adds it in quadrature to the statistical error of each of the three magnitudes .
after the dm has completed its imaging and analysis sequence , the appropriate observation mode is triggered automatically on the basis of the results of the analysis performed by the _ lt - trap _ on the dm images ( see fig .
[ fig : strategy ] and table [ tab : om ] ) .
this mode is triggered by the grb toca when the dm finds an ot candidate with the required confidence level .
it consists of a multi - color imaging sequence cycling through three sloan @xmath36 , @xmath3 and @xmath0 filters until the end of the first hour .
the ordered sequence , @xmath36 , @xmath3 and @xmath0 , is repeated with different exposure times : the first two times with 30-s exposure , then it continues with 60-s exposure cycles up to 18 times . before may 16 , 2005 , this mode operated in the same way but used a slightly different set of filters , @xmath37 , as used for grb 050502a @xcite .
the motivation for changing and optimizing the filter choice ( post may 16 ) was threefold : 1 ) the greater sensitivity at @xmath36 band , 2 ) the small separation between @xmath38 and @xmath7 filter central wavelengths ( @xmath39 and @xmath40 , respectively ) and 3 ) the recognized need for denser sampling of the light curves at early times . a key unsolved problem in the astrophysics of grbs is the geometry of the ejecta and the role of magnetic fields .
direct measurements of polarization at _ early times _ provide stringent constraints on current jet and internal shock models .
as described in section [ sec : lt ] , we will have unique access to a simple optical polarimeter , ringo , on the lt from the end of 2006 .
polarimetry mode ( pm ) will be triggered following the identification by _ lt - trap _ of a candidate ot with @xmath41 mag and high significance , and will consist of an automatic series of polarimetric exposures taken with ringo , with increasing exposure times : 30s , 60s , 120s , 240s , etc .
these exposures will not be reduced and analyzed in real - time , but post - processing will extract the @xmath0 band light curve and any polarization evolution of the ot .
although less sensitive than ratcam , ringo will detect polarization to a few % in @xmath42 15 mag ots in a 30-s exposure . in combination with the initial polarimetric exposure that will be obtained immediately
before the dm begins , this mode aims to measure the polarization properties from the first minutes after the burst . following commissioning of frodospec ( 2007 )
, the identification of a candidate ot with @xmath41 mag and high significance will result in the triggering of an automatic spectroscopic observation .
the goal of the initial spectroscopic observations will be to obtain an early redshift estimate , whilst subsequent spectra taken during the first hour will provide valuable information on the time evolution of the grb environment and light curve .
short exposure @xmath0 will be interspersed with spectroscopic observations to ensure the ot has not faded below the sensitivity limit of the spectrograph . in the case of a rapidly fading ot , the observing mode will revert to mcim after the initial spectrum has been obtained .
lll dm & 2 x ( 3x10 s in @xmath0 ) & ( 3x10 s in @xmath5 ) + ( 1x10 s in @xmath43 ) + rizm & ( @xmath44 x 2 min ) in ( @xmath0 , @xmath3 , @xmath2 ) , @xmath45 & + mcim & 2 x ( 30 s in @xmath46 ) + @xmath44 x ( 1 min in @xmath46 ) & cycles of @xmath47 : 1x30s , 1x1min , @xmath44x ( 2 min , 3 min ) + sm & for ots with @xmath41 mag ( expected in 2007 ) & @xmath48 mag + pm & 30s , 60s , 120s ... for ots with @xmath41 mag ( expected in 2006 ) &
+ when the dm does not identify an ot candidate , the grb toca invokes the `` riz mode '' .
this consists of a sequence of 2-min exposure @xmath0 , @xmath3 and @xmath2 images : first , one @xmath0 , one @xmath3 and one @xmath2 , then two @xmath0 followed by two @xmath3 and by two @xmath2 , then three @xmath0 followed by three @xmath3 and three @xmath2 and so on . prior to november 2005 , this mode consisted of @xmath49 cycles only ; we have subsequently adapted this mode to include additional @xmath2 exposures that are inserted at the end of each @xmath49 cycle to enable identification of possible higher redshift bursts ( z @xmath50 6 ) that may be faint in @xmath0 but brighter in @xmath2 .
this mode is designed to be sensitive to possible faint optical afterglows ( whether intrinsically faint or at higher redshift ) , allowing @xmath51 band light curves to be constructed when the ot is detectable in longer exposures but too faint to have been identified automatically by the detection mode , or to provide deep upper limits at early time when no ot is present . under average conditions , i.e. seeing of @xmath52 arcsec , 2-min exposure limiting magnitudes are around @xmath532122 , @xmath542021 and @xmath5520 .
the lt is the prime member of the global 2-m robotic telescopes network called `` _
robonet-1.0_. '' this network includes two other facilities : the faulkes telescope north ( ftn ) located in maui ( hawaii ) and the faulkes telescope south ( fts ) in siding spring ( australia ) , both mainly supported by the dill faulkes educational trust and intended for use by uk schools and various scientific observing programs .
all the three telescopes are operated remotely through the operations management centre in liverpool jmu and , when fully commissioned , will all operate in fully robotic mode . under the _ robonet-1.0 _
project , comprising a consortium of ten uk universities funded by the uk pparc , a fraction of time on the two fts is reserved for post first hour grb follow - up by consortium members ( see @xcite for details ) . following the successful operation of _ lt - trap _ on the lt
, it was deployed on the faulkes telescopes , with a slightly - modified observing mode choice following the ot identification stage ( see fig . [
fig : strategy ] ) .
fts is currently undergoing commissioning so is not yet available robotically ; the ftn is fully robotic and has performed a number of follow - up observations minutes after a grb ; for this reason , hereafter we will limit our discussion to ftn .
the rapid ( @xmath56 hr ) robotic follow - up observations of grbs on ftn is a collaborative project between liverpool john moores university and the university of leicester .
the optical filters available on the ft are different from the lt : bessell @xmath57 , sloan @xmath3 , neutral @xmath58 , @xmath59iii and @xmath60 .
the dm consists of only one set of three 10-s images in @xmath5 .
regardless of the results of the dm , three more 10-s images are acquired in the following filters , respectively : @xmath38 , @xmath7 , @xmath3 . in the case of identification of an ot candidate with @xmath48 , the grb toca will triggers a spectroscopic observation . as in the case of lt ,
the threshold on the confidence level for an ot candidate to be considered as a good candidate is currently set to 0.7 .
the logic of the selection of the ot candidate is exactly the same as for the lt ( sec .
[ sec : grb_pipe_var ] ) . presently , regardless of the possible identification of an ot candidate with @xmath61 and confidence level @xmath62 from the dm , the grb toca triggers a sequence of multi - color observations according to the following scheme : cycles of @xmath63 with increasing exposure times : 30 s ( once ) , 60 s ( once ) , then it goes on continuously switching between 120 s and 180 s exposures in order to limit the effects of tracking problems .
although the number of grbs so far observed is still small , we have attempted to estimate the reliability of the ot candidates automatically identified by the _ lt - trap _ as follows . for each of the grbs followed up robotically within minutes , we counted the ot candidates identified as a function of their confidence level .
when the confidence level is above the threshold ( currently set to 0.7 ) , the ot is taken to be a true ot candidate ( toc ) , otherwise it is a fake ot candidate ( foc ) .
when a true afterglow is present , we call it a true ot ( to ) ; similarly , if any non - grb source that could mimic a grb afterglow is present , we call it a fake ot ( fo ) .
let @xmath64 be the probability that a to is automatically identified as a toc .
the closer @xmath64 to 1 , the better the _ lt - trap _ capability of identifying genuine grb afterglows .
likewise , let @xmath65 be the probability that a fo is automatically identified as a foc .
the closer @xmath65 to 1 , the better the _ lt - trap _ capability of rejecting fake grb afterglows . in practice
we do know that @xmath64 and @xmath65 are somehow correlated : a low threshold on the confidence level would increase @xmath64 but also decrease @xmath65 .
the opposite is true for a high value of the same threshold .
so far , the current value ( 0.7 ) has turned out to be a good trade - off . however , as a first approximation we treat them as unrelated and eventually we discuss the opposite case of total correlation .
let @xmath66 and @xmath67 the total number of to observed and the total number of to identified as toc , respectively .
likewise , let @xmath68 and @xmath69 the total number of fo observed and the total number of fo identified as foc , respectively .
the probability @xmath70 ( @xmath71 ) to identify @xmath67 ( @xmath69 ) toc ( foc ) out of @xmath66 to ( @xmath68 fo ) , given @xmath64 ( @xmath65 ) , is given by the binomial distribution ( under the sensible assumption that different grbs are independent from each other ) : @xmath72 we do not know either @xmath64 or @xmath65 , but so far we counted the following : @xmath73 , @xmath74 ; @xmath75 , @xmath76 ( in fact _ lt - trap _ so far correctly identified both @xmath77 ots and failed to reject 2 out of 15 fake ots ) . from the bayes theorem
, we derive the probability @xmath78 to have @xmath79 , given @xmath80 and @xmath81 : @xmath82 we then apply the maximum likelihood method and find the value for @xmath79 which maximizes @xmath78 . to this end ,
the denominator of eq .
[ eq : bayes ] can be ignored . concerning the knowledge of the prior @xmath83 , in both cases as a first guess we may assume the most simple case of a uniform distribution
. then we refine it thanks to the information derived from our tests , according to which a sensible approximation is given by a truncated normal distribution centered on 0.8 and sigma of 0.3 .
however , it must be pointed out that the prior strongly depends on the kind of afterglow population one considers . for this reason
, we consider these two opposite cases of uniform and truncated normal distributions .
when a uniform prior is assumed , the best value is straightforwardly given by @xmath84 : @xmath85 and @xmath86 .
when we assume a more refined prior , i.e. @xmath87 , the best values are @xmath88 ( fig . [
fig : pp ] , solid line ) and @xmath89 .
eventually , we can provide confidence intervals on both @xmath64 and @xmath65 at given levels from the distributions obtained with the truncated normal priors : @xmath90 and @xmath91 ( 50% cl ) ; @xmath92 and @xmath93 ( 90% cl ) . if we take into account the correlation between @xmath64 and @xmath65 , the total probability of eq .
[ eq : bayes ] is replaced by the more general one : @xmath94 at this stage , it is difficult to model the anticorrelation between @xmath64 and @xmath65 in the bivariate prior @xmath95 , particularly for the small sample of grbs so far collected .
we then studied the opposite case of a total anticorrelation between the two variables , in which @xmath65 is completely determined by the value of @xmath64 , by solving eq .
[ eq : anticorr ] : @xmath96 where @xmath97 is the same expression derived in eq .
[ eq : bayes ] , assuming truncated normal priors .
the meaning of eq .
[ eq : anticorr ] is that , for each value @xmath98 , @xmath99 is determined so that the probability that @xmath100 , is equal to the probability that @xmath101 ; it is straightforward to verify that the greater @xmath99 , the smaller @xmath98 and vice versa .
this is just one sensible assumption of total anticorrelation among other possible alternative assumptions .
figure [ fig : pp ] shows the probability density for @xmath64 derived in this case of total anticorrelation ( dashed line ) .
the best values for @xmath64 and @xmath65 and their confidence intervals derived in this case ( truncated normal priors ) are the following : @xmath102 and @xmath103 ( 50% cl ) ; @xmath104 and @xmath105 ( 90% cl ) .
remarkably , in spite of the opposite cases of variables @xmath64 and @xmath65 either totally unrelated or totally anticorrelated , the results seem to give consistent confidence intervals , as shown by fig . [
fig : pp ] .
the wide confidence interval of @xmath64 is understandably due to the low number of to observed so far , rather than the limits of the _ lt - trap_. we expect to give more precise estimates of both probabilities as soon as the sample of grb afterglows detected is more numerous .
to - date ( october 2005 ) , over a period of two months , lt followed up in a fully automated fashion using the real - time pipeline six grbs and ftn followed up five more .
table [ tab : results ] reports for each of these eleven follow - up observations the start time from the grb trigger , the filters used , the number of frames acquired and the gcn circulars issued by the lt / ftn collaboration reporting on the corresponding lt / ftn observations . the most successful case so far is represented by the automatic detection of the afterglow of grb 050502a @xcite followed by the acquisition of the first early ( @xmath56hr ) multi - color light curve @xcite .
this latter case is also notable for longer term follow - up using the _ robonet-1.0 _ network .
the other case of prompt detection is grb 050713a @xcite , although in this case the afterglow was not identified automatically because of the poor quality of the images affected by the presence of a @xmath106 star in the field , but recognized afterward by visual inspection .
llllrlrc ftn & 050412 & _ swift _ & @xmath107 & 2.5 & @xmath108 & 23 & none + lt & 050502a & _ integral _ & @xmath37 & 3.1 & @xmath109 & 25 & 3325 + ftn & 050504 & _ integral _ & @xmath107 & 3.7 & @xmath110 & 38 & 3351 + lt & 050520 & _ integral _ & @xmath49 & 4.5 & @xmath111 & 18 & 3437 + lt & 050528 & _ swift _ & @xmath49 & 2.5 & @xmath112 & 36 & 3497 + lt & 050713a & _ swift _ & @xmath0 & 2.4 & @xmath113 & 3 & 3588 + ftn & 050713b & _ swift _ & @xmath5 & 3.3 & @xmath114 & 6 & 3592 + ftn & 050716 & _ swift _ & @xmath107 & 3.8 & @xmath115 & 20 & 3625 + lt & 050730 & _ swift _ & @xmath49 & 50 & @xmath116 & 36 & 3706 + lt & 050904 & _ swift _ & @xmath49 & 3.8 & & 31 & none + ftn & 050925 & _ swift _ & @xmath107 & 3.3 & @xmath117 & 12 & 4035 + the power and robustness of the _ lt - trap _ is illustrated in the case of grb 050730 @xcite : this grb occurred before twilight at the lt site , so was triggered manually and , although the ot was not recognized during the dm because of the high sky background due to the sky not yet being completely dark , it was automatically identified in the subsequent rim as an unknown fading source of @xmath118 at @xmath119 min after the grb . in the other cases , the combination of sensitivity and rapid response made it possible to derive deep upper limits , as in the cases of grb 050504 with @xmath110 @xcite and grb 050716 with @xmath115 @xcite 34 min after the grb trigger time . in the future ,
we plan to refine the strategy when an ot candidate with @xmath61 and confidence level @xmath62 is found from the dm ; in particular , exposure times will be tuned dynamically on the basis of the estimated magnitude of the best ot candidate .
automatic polarimetry , near - infrared and spectroscopy follow - up modes will be implemented on the lt following completion of instrument commissioning .
cg and ag acknowledge their marie curie fellowships from the european commission .
cgm acknowledges financial support from the royal society .
am acknowledges financial support from the uk pparc .
mfb is supported by a pparc senior fellowship .
the liverpool telescope is operated on the island of la palma by liverpool john moores university at the observatorio del roque de los muchachos of the instituto de astrofisica de canarias .
the faulkes telescope north is operated with support from the dill faulkes educational trust .
gomboc , a. , et al . , 2005a , proc .
of the 4th workshop gamma
ray bursts in the afterglow era , rome , 2004 , eds : piro , l. , amati , l. , covino , s. , & gendre , b. , il nuovo cimento , in press ( preprint : astro - ph/0502505 ) | the 2-m liverpool telescope ( lt ) , owned by liverpool john moores university , is located in la palma ( canary islands ) and operates in fully robotic mode . in 2005 ,
the lt began conducting an automatic grb follow - up program .
on receiving an automatic grb alert from a gamma - ray observatory ( _ swift _ , _ integral _ , _ hete - ii _ , _ ipn _ )
the lt initiates a special override mode that conducts follow - up observations within 23 min of the grb onset .
this follow - up procedure begins with an initial sequence of short ( 10-s ) exposures acquired through an @xmath0 band filter .
these images are reduced , analyzed and interpreted automatically using pipeline software developed by our team called `` _ lt - trap _ '' ( _ liverpool telescope transient rapid analysis pipeline _ ) ; the automatic detection and successful identification of an unknown and potentially fading optical transient triggers a subsequent multi - color imaging sequence . in the case of a candidate brighter than @xmath1 , either a polarimetric ( from 2006 ) or a spectroscopic observation ( from 2007 ) will be triggered on the lt . if no candidate is identified , the telescope continues to obtain @xmath2 , @xmath0 and @xmath3 band imaging with increasingly longer exposure times .
here we present a detailed description of the _ lt - trap _ and briefly discuss the illustrative case of the afterglow of grb 050502a , whose automatic identification by the lt just 3 min after the grb , led to the acquisition of the first early - time ( @xmath41 hr ) multi - color light curve of a grb afterglow . |
What was supposed to be one man’s special day at Disney World turned out to be less than magical.
Marc Rubin, 57, who was visiting from New York, had plans to propose to his girlfriend in front of Cinderella’s Castle, but things went awry when he got into an altercation with a park employee who asked he move from the parade route.
EASYJET PASSENGER REMOVED FROM FLIGHT FOR SMOKING IN BATHROOM, 'PUTTING WHOLE PLANE IN DANGER'
When the cast member, Nicole Guzman-Ortiz, 24, made the request, Rubin reportedly screamed at her, grabbed her shirt and threatened to punch her in the face, according to the arrest report.
But Rubin is now suing Walt Disney Parks and Resorts for more than $15,000 over the 2015 incident, claiming he was falsely accused of battery and wrongfully arrested, according to a lawsuit filed late last month.
The suit claims Rubin was “willing to accommodate” Ortiz’ request to move, but asked for a “brief delay” so the rest of his group, who were minors, could return from a concession stand they had gone to — he said he didn't want to lose sight of them. However, his request was denied by the park employee, despite “legitimate safety concerns.”
Shortly after the apparent altercation between Rubin and Ortiz, her manager came over to assist with the situation. At that time, Rubin reportedly became loud and aggressive toward him, as well, the arrest report states.
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While the manager didn’t witness Rubin grab Ortiz, he told police he witnessed Rubin’s “demeanor and arrogance.”
Rubin was escorted to the park’s security office and later arrested and charged. He had planned to propose at the conclusion of the night’s festivities.
A spokesperson for Disney told Fox News, "The safety of the people who work in and visit our parks is very important to us. We will respond to the allegations as appropriate in court.” ||||| A Suffolk County man is suing Walt Disney World, claiming he was falsely arrested after a 2015 dispute with a park employee over his marriage proposal plans.
Marc Rubin, 57, said in court documents he had hoped to propose to his now-wife in front of Cinderella’s Castle at the Magic Kingdom park after a parade when a Disney employee requested he move from his intended spot.
Rubin said in the suit that he was falsely accused of battery by park staff and detained by the Orange County Sheriff’s Office.
Rubin is seeking at least $15,000 in damages and other costs. The suit was filed Sept. 27 in Orange County Circuit Court.
“The safety of the people who work in and visit our parks is very important to us,” a Disney spokeswoman said in a statement. “We will respond to the allegations as appropriate in court.”
Rubin’s attorney, John W. Zielinski, of Orlando, Florida, did not respond to a request for comment.
According to Rubin’s suit, the July 8, 2015, proposal was “an event that was intended to be one of the most important” of his life. After the theme park’s nightly parade, Rubin said he staked out a spot in front of the castle while his girlfriend and other family members, including two teens, visited a concession cart.
Rubin said he was then approached by a female park employee who asked him to move from the location. According to court documents, Rubin was willing to move, but asked to stay until his family returned.
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An argument followed, with Rubin and the park offering different accounts of what happened. Rubin said he never touched the employee and that the employee continued to insist he move “without regard to the legitimate safety concerns” about Rubin being separated from his family.
According to a sheriff’s office arrest report obtained by Disney, the park employee said she asked Rubin to move out of the parade route, about 3 feet, and that he refused to do so, becoming angry. The employee told police that Rubin threatened to have her fired and grabbed her shirt when she turned around to walk away.
The employee then called security. Her manager told police that he arrived to find Rubin screaming at the employee. He said Rubin then argued with him as well and grabbed his shirt, too, though he declined to press charges.
A sheriff’s office representative was not available for comment.
According to court records, Rubin was arrested and charged with misdemeanor battery. He pleaded no contest to a disorderly conduct charge and paid a fine of $100, plus court costs, in 2015.
Rubin claims in the court documents that Disney World failed to provide surveillance video he said would have exonerated him and failed to conduct an internal investigation before reporting the incident to the sheriff’s office, among other claims.
He said he “suffered injury and resulting pain and suffering, mental anguish, loss of capacity for the enjoyment of life, embarrassment and humiliation, loss of earnings, and loss of ability to earn money” as a result of his arrest. | – A Long Island man thought July 8, 2015, was going to be "one of the most important" days of his life, but now he's suing Disney World for ruining it. Fox News reports on Marc Rubin's lawsuit, which the 57-year-old filed Sept. 27 in Florida's Orange County Circuit Court, and which outlines how he claims a Disney employee marred his marriage proposal plans. Per his suit, Rubin was planning to ask for his girlfriend's hand in marriage in front of Cinderella Castle on that summer day, but as he was looking for just the right spot to do it, he says he was approached by park worker Nicole Guzman-Ortiz, 24. Per an arrest report, Guzman-Ortiz says she asked Rubin to move three feet to make way for a soon-to-start parade and he refused; in his suit, Rubin says he was waiting for minors he was with to come back from the concession stand and needed to stay in place for "legitimate safety concerns." Per the arrest report on the ensuing argument, Guzman-Ortiz says Rubin then threatened to make sure she was fired and yanked on her shirt collar when she tried to leave, Newsday notes. A manager who arrived on the scene told police he didn't see Rubin grab Guzman-Ortiz's collar, but he did witness Rubin's "arrogance"; he says Rubin grabbed his shirt as well. Rubin was arrested for misdemeanor battery, pleaded no contest to a disorderly conduct charge, and paid a $100 fine, plus court costs. His claim, which asks for at least $15,000 in damages and other costs, notes he's also suing for negligence, claiming the park didn't release surveillance footage that would've shown he never touched anyone. "The safety of the people who work in and visit our parks is very important to us," a Disney rep says in a statement. "We will respond to the allegations as appropriate in court." |
even if rarely , breast cancer ( bc ) affects men . to date , in western countries , male breast cancer ( mbc ) is < 1% of all breast tumors and < 1% of all cancers in men , , .
recent epidemiological studies suggest that the incidence of mbc is increasing by 1.1% per year , .
mbc incidence is generally low compared with the female bc ( fbc ) , but there is substantial variation between countries .
the highest overall rates adjusted for age occur in israel ( 1.08 per 100,000 person - years ) , while the rates are the lowest in southeast asia , particularly in thailand ( 0.14 per 100000 person - years ) .
the reason for this variability is to be found mainly in the genetic susceptibility for the population .
common factors bc risk , such as genetic , hormonal and environmental factors , are involved in the pathogenesis of bc in women as in men .
the main predisposing factor mbc is a positive family history ( fh ) of bc .
patients with a positive first degree fh have a 2.0 times greater risk , which increases to more than 5.0 times with the number of affected relatives and relatives of the first onset , thus suggesting an important role of genetic factors in the risk of mbc . from an epidemiological point of view , the male breast cancer mbc is similar to the female postmenopausal and , in general , treatment mbc follows the same indications postmenopausal fbc . however
, the clinical and pathological features of mbc do not exactly match those of the fbc and this would explain why mortality rates and survival are significantly lower in male than in female patients . and
now estimated that up to 10% of all the mbcs are hereditary forms caused by germline mutations in inherited well identified susceptibility genes bc . with their mutation frequency and extent of their impact in bc susceptibility
mutations in two genes leading bc high risk , brca1 and brca2 , occur infrequently in the population , but give it a high risk of bc for the individual , .
the moderate risk of bc is determined by genetic variants associated with brca1/2 pathways in dna repair .
these variations occur in < 1% of the population , and their contribution to the risk of bc is < 5% , .
the low penetrance , however , makes their function of onset of the disease still barely comprehensible .
doubtless , brca1 and brca2 are the major susceptibility genes in high - risk families . in cases
these are responsible for 6076% of mbc occur in high - risk families , while the frequency of brca1 mutations varies from 10% to 16% , , , .
the vast majority of brca1/2 mutations are truncating mutations ; however , it was also identified a large number of missense variants . at present
, there is no evidence of a correlation between the position of the mutation in the brca1 or brca2 gene and the risk of mbc .
brca1/2 polymorphic variants may also be associated with an increased risk of bc , , , .
interestingly , as there is an association between the variant brca2 n372h and the risk of mbc in young men , .
specific mutations in brca1 and brca2 show high frequency in specific countries or ethnic groups , in particular , genetically isolated populations ; this would explain the higher incidence ( > 2% in total ) in the ashkenazi jewish male population than the general population of the united states , , , .
recently were studied specific brca - associated phenotypes otherwise identified in mbc , ; it was discovered that most of the mbc brca1-related are negative her2 ( her2 ) , and grade 3 tumors show high proliferative activity . in the study that we propose
, we evaluated the clinical pathological characteristics , biological and genetic implications , treatment and prognosis of cases of mbc treated in the breast unit of the hospital
it was performed analysis regarding cases of mbc treated in twenty years in a single center .
inclusion criteria were male patients > 18 years with localized breast cancer , locally advanced or metastatic .
we excluded from the study patients who had no follow - up after initial diagnosis .
all the diagnosis of breast cancer had preoperative histological confirmation ; tumoral staging was performed with the 2007 edition of the tnm classification .
the tumor histological classification was performed using the scarff - bloom and richardson ( sbr ) system histology .
immuno histochemical analysis to determine the estrogen ( er ) and progesterone receptor ( pr ) status was performed using standard procedures on 4 micron paraffin sections of tissue samples stained with the monoclonal antibodies 6f11 and 1a6 for er and pr , respectively .
the description of the clinical data was produced in percentage or in terms of mean and median standard deviation .
survival was calculated using the kaplan meier method , and for the evaluation of the relationship between the explanatory variables was used the program xlstat
the treatment of each patient was determined by the medical staff of the breast unit , while the consent , signed by all the patients , was approved by the multidisciplinary oncology group and by the ethics committee of the hospital .
it was performed analysis regarding cases of mbc treated in twenty years in a single center .
inclusion criteria were male patients > 18 years with localized breast cancer , locally advanced or metastatic .
we excluded from the study patients who had no follow - up after initial diagnosis .
all the diagnosis of breast cancer had preoperative histological confirmation ; tumoral staging was performed with the 2007 edition of the tnm classification .
the tumor histological classification was performed using the scarff - bloom and richardson ( sbr ) system histology .
immuno histochemical analysis to determine the estrogen ( er ) and progesterone receptor ( pr ) status was performed using standard procedures on 4 micron paraffin sections of tissue samples stained with the monoclonal antibodies 6f11 and 1a6 for er and pr , respectively .
the description of the clinical data was produced in percentage or in terms of mean and median standard deviation .
survival was calculated using the kaplan meier method , and for the evaluation of the relationship between the explanatory variables was used the program xlstat
the treatment of each patient was determined by the medical staff of the breast unit , while the consent , signed by all the patients , was approved by the multidisciplinary oncology group and by the ethics committee of the hospital .
santa maria in terni , italy , with a diagnosis of breast cancer between january 1995 and december 2014 were retrospectively analyzed and evaluated in terms of general characteristics and survival .
the median time for the consultation was 28 months ( range : 348 months ) . according to the tnm classification
, tumors were classified as t1 : 4 cases ( 9% ) , t2 : 9 ( 18.5% ) , t4 and t3 , 25 and 9 cases , respectively , 52.5% and 20% . in 27 patients ( 57.2% ) ,
locally advanced disease was classified as n1 , while in 25.2% of cases ( 12 patients ) was classified as n2 .
he was diagnosed with invasive ductal carcinoma ( idc ) in 45 cases ( 95% ) ; for the two remaining cases this was infiltrating ductal carcinoma with paget 's disease of the breast ( 2.5% ) and infiltrating lobular carcinoma ( ilc ) ( 2.5% ) . according to the classification scarff - bloom richardson grade ii or iii was predominant ( 82% of cases ) .
axillary lymph nodes containing metastases ( n+ ) in 79.4% of cases ( 39 patients ) .
both estrogen receptor ( er ) and progesterone receptor ( pr ) were positive in 67% ( 31 patients ) .
santa maria in terni , italy , with a diagnosis of breast cancer between january 1995 and december 2014 were retrospectively analyzed and evaluated in terms of general characteristics and survival .
the median time for the consultation was 28 months ( range : 348 months ) . according to the tnm classification
, tumors were classified as t1 : 4 cases ( 9% ) , t2 : 9 ( 18.5% ) , t4 and t3 , 25 and 9 cases , respectively , 52.5% and 20% . in 27 patients ( 57.2% ) ,
locally advanced disease was classified as n1 , while in 25.2% of cases ( 12 patients ) was classified as n2 .
he was diagnosed with invasive ductal carcinoma ( idc ) in 45 cases ( 95% ) ; for the two remaining cases this was infiltrating ductal carcinoma with paget 's disease of the breast ( 2.5% ) and infiltrating lobular carcinoma ( ilc ) ( 2.5% ) . according to the classification scarff - bloom richardson grade ii or iii was predominant ( 82% of cases ) .
axillary lymph nodes containing metastases ( n+ ) in 79.4% of cases ( 39 patients ) .
both estrogen receptor ( er ) and progesterone receptor ( pr ) were positive in 67% ( 31 patients ) .
thirty - four patients ( 71% ) were treated with radical mastectomy ( rm ) , while the modified radical mastectomy ( mrm ) was performed in three cases ; in the other three cases was performed simple mastectomy ( sm ) , without lymph node dissection , and in only one case was performed lumpectomy . in six patients ( 13% ) was determined only palliative treatment .
twenty - three patients of thirty - four patients received radiation therapy ; the median dose delivered was 50 gy to the breast , chest wall and regional lymph nodes .
chemotherapy ( anthracycline - based protocol , ac60 or fec 100 ) was given in the neoadjuvant situation in two cases , in adjuvant situation in nine cases .
hormone therapy was delivered in twenty patients adjuvant situation : tamoxifen alone in 20 cases , tamoxifen with orchiectomy in one case .
table 2 summarizes the methods of treatment according to the tnm stage . during the median follow - up of 38 months ( 3168 months ) ; evolution has been characterized by local recurrences in eight cases ( 17% of all patients ) .
the site of bone metastases was in six cases ; lung in four cases ; liver in two cases ; liver and skin in one case and pleura and skin in one case .
the 5 and 10 year overall survival ( os ) rates were 63% and 55% .
male breast cancer has many similarities to breast cancer in women , but there are distinct functions that need to be appreciated . in recent years , there has been an increase in the incidence of this disease .
review of surveillance , epidemiology and end result data ( seer ) indicate an increased incidence of male breast cancer , from 1.0 per 100,000 men in the late 1970s to 1.2 per 100,000 men from 2000 to 2004 , ; this value of incidence has increased steadily , so that in some countries have already led to 1.4 per 100,000 men .
the average age at diagnosis for men with breast cancer is 67 years , which is about 510 years the average age at diagnosis for women , .
the average age of our patients ( 62 years ) is slightly lower than that of other series .
the male breast cancer is probably caused by the concomitant effects of various risk factors , including clinical disorders related to hormonal imbalances , some occupational exposures and environmental and genetic risk factors , for example , a family history of breast cancer and mutations in the breast cancer predisposing genes , like the brca genes , and possibly other .
similar to breast cancer in women , mbc is likely to be caused by the concurrent effects of different risk factors , including clinical disorders relating to hormonal imbalances , certain occupational and environmental exposures , and genetic risk factors , for instance a positive family history ( fh ) of breast cancer ( bc ) and mutations in bc predisposing genes , such as brca genes , and possibly others . as is the case in female bcs , mbcs are highly sensitive to hormonal changes .
in particular , hormonal imbalance between an excess of estrogen and a deficiency of testosterone increases the risk of the disease .
this imbalance may occur endogenously due to testicular abnormalities , including , undescended testes , congenital inguinal hernia , orchitis , orchiectomy and testicular injury .
in general , liver damage and disease , caused by the effects of several drugs or their metabolites , may affect hepatic functions and lead to hyperestrogenism .
obesity is one of the most common causes of hyperoestrogenization in men because of increased peripheral aromatization of androgens .
klinefelter s syndrome , characterized by 47xxy karyotype , testicular dysgenesis , gynecomastia , low testosterone concentrations and increased gonadotrophins , is strongly associated with mbc risk .
individuals with this syndrome have a 2050 times higher risk over the general male population .
an upset in estrogen or androgen balance is a causal factor in gynecomastia , which is extremely common in pubescent boys , may occur in men over the age of 50 and is found in 638% of male pts affected by bc .
however , the incidence of gynecomastia in mbc pts is no higher than in the general male population ; gynecomastia , therefore , does not in itself seem to represent a risk factor for mbc , . as in women ,
ionizing radiations have been considered as possible causal cofactors in the etiology of mbc , .
occupational exposure to heat and electromagnetic radiation are postulated to be linked to mbc risk . a higher frequency of breast cancer
is reported in men who have worked in hot environments , such as blast furnaces , steel works , rolling and finishing mills , , possibly because long - lasting exposure to high ambient temperatures can lead to testicular failure . as for women ,
alcoholic beverages seem to represent a risk factor for the development of mbc , with an increase of 16% for each increase of 10 g / day of alcohol intake .
moreover , strong consumers of alcoholic beverages ( more than 90 g / day ) present a 6-fold increased or to develop mbc when compared to light consumers ( < 15 g / day ) , .
overall , with the exception of alcohol consumption , dietary factors seem to play a marginal role in the etiology of mbc .
similar to fbc , a positive fh of bc is associated with increased risk of mbc .
data from population - based studies have shown that about 20% of all mbc pts have a history of bc in a first - degree female relative , , , , , , .
in general , a positive fh of either female or male breast cancer among first - degree relatives confers a 23-fold increase in mbc risk , , , , , , , , , , , , ,
. the risk increases with increasing numbers of first - degree relatives affected and with early onset in affected relatives .
in addition to bc families , mbc cases have also been reported in families with the hereditary non - polyposis colorectal cancer ( hnpcc ) syndrome , and cowden syndrome , .
a personal history of a second primary tumor is reported in more than 11% of mbc pts , .
mbc predisposition can result from germ - line mutations in the high - penetrance brca2 ( omim # 6600185 ) and , with lower frequency , brca1 ( omim # 113705 ) genes . the presence of mbc within high - risk bc families indicates a high likelihood of brca2 mutations with a frequency ranging from 60 to 76% , whereas brca1 mutations frequency ranges from 10 to 16% , , , .
brca2 mutations are currently considered as the major genetic risk factor for mbc , however , there is no evidence for a correlation between the location of the mutation within brca2 gene and risk of mbc .
the median age at bc diagnosis among brca2 mutation carriers is earlier ( median , 58.8 years ) than that of negative cases ( median , 67.9 years ) .
male carriers of brca2 germ - line mutations have a higher risk of developing bc than men in the general population .
male brca2 mutation carriers have been estimated to have a lifetime risk of 6.9% for developing bc , which is approximately 80100 times higher than in the general population .
the most common clinical sign of breast cancer onset in men is a painless palpable swelling sub areolar .
other symptoms may include involvement nipple , with retraction and/or ulceration and/or bleeding , axillary lymphadenopathy and gynecomastia , . because male breast lobules has not fully formed , the male type of breast cancer is the most common invasive ductal carcinoma ( idc ) ( 8595% ) , .
the result of our study was comparable with a ratio of 95% for idc and this was significantly higher than the other histological types .
lobular carcinoma in situ , paget 's disease , and inflammatory breast cancer have rarely been described in males .
positivity rate receptor is more common in men with breast cancer , compared to women . in several studies , er and pr positivity was reported 7593% , . in our study , both the estrogen receptor ( er ) and progesterone receptor ( pr ) were positive in 67% .
however , recent studies are in favor of the amendment radical mastectomy or simple combination with radiotherapy .
postoperative radiotherapy does get local control , but no effect was observed on survival . in men treated with mastectomy , adjuvant radiation therapy has been shown to decrease local recurrence .
tamoxifen has been shown to lead to increased survival rates in women with hormone - sensitive disease and today is generally considered the standard adjuvant treatment for male breast cancer hormone - dependent . the tolerance of the drug has not been sufficiently studied in males , and its main side effects are deep vein thrombosis , reduced libido , impotence , mood swings and hot flashes . the chemotherapy should be used in case of absence or doubt on endocrine - reactivity .
the taxanes may be considered when the lymph nodes are involved . regarding the use of adjuvant trastuzumab , since there are no specific data , its use should be considered based on the patient and tumor characteristics .
the survival rate at 5 and 10 years overall patient with male breast cancer are about 60 and 40% , respectively , .
the number of histologically positive axillary lymph nodes and tumor size were significant prognostic factors .
another negative prognostic factor is the advanced age at the time of diagnosis , as the increased presence of comorbidities may limit the possibility of treatment .
we believe , while recognizing that much will be clarified by a better knowledge of their genetic engineering and epigenetic , extremely important collection of studies and pilot retrospective series .
efforts to develop randomized , prospective studies in cooperative groups and other consortia clinical trials are essential .
alessandro sanguinetti , nicola avenia : participated substantially in conception , design , and execution of the study and in the analysis and interpretation of data ; also the drafted and editing of the manuscript .
andrea polistena , roberta lucchini , massimo monacelli , sergio galasse , stefano avenia , roberta triola , walter bugiantella , fausto rondelli , roberto cirocchi : participated substantially in conception , design , and execution of the study and in the analysis and interpretation of data . | highlightsmale breast cancer ( mbc ) is a rare disease representing less than 1% of all malignancies in men andonly 1% of all incident breast cancers.management consisted especially of radical mastectomy ; followed by adjuvant radiotherapy and hormonal therapy with or without chemotherapy.future research for better understanding of this disease at national or international level are needed to improve the management and prognosis of male patients . |
autoimmune pancreatitis ( aip ) and pancreatic cancer have recently been reported.[15 ] in such cases , cytological examination can be difficult due to sclerosis , inflammation and reactive atypia in the corresponding tissue .
in cytological examinations , some authors have reported that when a smear preparation exhibits a predominance of inflammatory cells ( lymphocytes and plasma cells ) with sparse epithelial cells lacking atypia , a cytological diagnosis of aip may be possible . here , we report , a case of invasive pancreatic ductal carcinoma with marked lymphoplasmacytic infiltration . although ductal cancer was suggested based on endoscopic ultrasound guided fine - needle aspiration ( eus - fna ) cytology findings , other medical examinations indicated chronic pancreatitis or aip .
a 75-year - old man without a history of malignancy was referred to our institution because of weight loss and a mass lesion in the pancreas tail .
the patient 's cea level was elevated ( 12.7 ng / ml ; normal , 0 - 6 ng / ml ) , but the ca 19 - 9 level was within the normal range ( 25.6 u / ml ; normal , 0 - 37.0 u / ml ) .
no increase was noted in the serum amylase level ( 51 iu / l ; normal value , 25 - 120 iu / l ) or the lipase level ( 22 u / l ; normal value , 13 - 49 u / l ) .
dynamic - enhanced computed tomography ( ct ) imaging showed a mass measuring 20 mm in the tail of the pancreas with no dilation of the main pancreatic duct , anomalous arrangement of the pancreaticobiliary ducts , or obstructive jaundice .
endoscopic retrograde cholangiopancreatography ( ercp ) revealed a narrowing of the main pancreatic duct at the tail .
these results suggested that the mass lesion in the pancreas was caused by chronic pancreatitis or autoimmune pancreatitis , rather than a pancreatic carcinoma .
further laboratory tests showed a normal igg level ( 1100 mg / ml ; normal , 800 - 1800 mg / ml ) , a normal igg4 level ( 67.0 mg / ml ; normal , 4 - 180 mg / ml ) and the absence of antinuclear antibody .
the eus - fna specimens showed a mixture of abnormal columnar epithelia and abundant lymphocytes .
smear preparations of the eus - fna materials from the pancreas tumor were stained using diff - quik solution .
cytoblocks were made by allowing the aspirated materials to clot in 10% buffered formalin , followed by treatment in alginic acid .
the smear preparations showed numerous lymphocytes including plasma cells with necrotic material [ figure 1a ] and small clusters of atypical epithelial cells [ figure 1b ] .
the atypical cells had a high nuclear to cytoplasmic ratio ; the cells were hyperchromatic and contained prominent nucleoli .
the papanicolaou - stained smear preparations and the cytoblock preparations showed similar findings . in the cytoblock specimens , some plasma cells were immunoreactive to anti - igg4 antibody .
( a ) numerous lymphocytes and plasma cells with necrotic material and fibrosis are visible ( diff - quik , 400 ) ; ( b ) atypical epithelial cells ( diff - quik , 1000 ) ; ( c ) the cut surface of the resected specimen show an elastic , hard , white mass that was located in the pancreas tail ; ( d ) ductal adenocarcinoma with lymphoplasmacytic infiltration was visible ( h and e , 100 ) ; ( e ) immunohistochemical findings showed abundant igg4-positive plasma cells around the pancreatic duct and cancer cells ( ihc , 100 ) the cut surface of the resected pancreas showed an elastic , hard , white mass in the pancreas tail [ figure 1c ] . in the histopathologic examination , intralobular and interlobular
no granulocytic epithelial lesions were found , so these histological features were compatible with the characteristics of type 1 autoimmune pancreatitis - lymphoplasmacytic sclerosing pancreatitis ( type 1 aip - lpsp ) .
invasive ductal adenocarcinoma with lymphoplasmacytic infiltration was also observed in these lesions [ figure 1d ] .
immunohistochemical staining , revealed abundant igg4-positive plasma cells ( > 50 cells per high - power field [ hpf ] ) around the pancreatic duct and tumor cells [ figure 1e ] .
the pathological diagnosis was moderately differentiated tubular adenocarcinoma with abundant lymphoplasmacytic infiltration and aip - lpsp features .
smear preparations of the eus - fna materials from the pancreas tumor were stained using diff - quik solution .
cytoblocks were made by allowing the aspirated materials to clot in 10% buffered formalin , followed by treatment in alginic acid .
the smear preparations showed numerous lymphocytes including plasma cells with necrotic material [ figure 1a ] and small clusters of atypical epithelial cells [ figure 1b ] .
the atypical cells had a high nuclear to cytoplasmic ratio ; the cells were hyperchromatic and contained prominent nucleoli .
the papanicolaou - stained smear preparations and the cytoblock preparations showed similar findings . in the cytoblock specimens , some plasma cells were immunoreactive to anti - igg4 antibody .
( a ) numerous lymphocytes and plasma cells with necrotic material and fibrosis are visible ( diff - quik , 400 ) ; ( b ) atypical epithelial cells ( diff - quik , 1000 ) ; ( c ) the cut surface of the resected specimen show an elastic , hard , white mass that was located in the pancreas tail ; ( d ) ductal adenocarcinoma with lymphoplasmacytic infiltration was visible ( h and e , 100 ) ; ( e ) immunohistochemical findings showed abundant igg4-positive plasma cells around the pancreatic duct and cancer cells ( ihc , 100 ) the cut surface of the resected pancreas showed an elastic , hard , white mass in the pancreas tail [ figure 1c ] .
in the histopathologic examination , intralobular and interlobular fibrosis was observed , with numerous lymphocyte and plasma cell infiltrations .
no granulocytic epithelial lesions were found , so these histological features were compatible with the characteristics of type 1 autoimmune pancreatitis - lymphoplasmacytic sclerosing pancreatitis ( type 1 aip - lpsp ) .
invasive ductal adenocarcinoma with lymphoplasmacytic infiltration was also observed in these lesions [ figure 1d ] .
immunohistochemical staining , revealed abundant igg4-positive plasma cells ( > 50 cells per high - power field [ hpf ] ) around the pancreatic duct and tumor cells [ figure 1e ] .
the pathological diagnosis was moderately differentiated tubular adenocarcinoma with abundant lymphoplasmacytic infiltration and aip - lpsp features .
in the current report , we were able to make a correct diagnosis of pancreatic carcinoma based on the presence of atypical epithelial cells in eus - fna specimens with concomitant aip - lpsp features .
the differentiation of pancreatic ductal adenocarcinoma from focal chronic pancreatitis , such as autoimmune pancreatitis , is particularly difficult in some cases . indeed , although aip can be well controlled with corticosteroids , some patients undergo a pancreatic resection . this diagnostic and management dilemma has been discussed in detail .
the proposed criteria for diagnosing aip include radiological studies , laboratory examinations , histopathological features , and response to steroid therapy.[79 ] because a definitive diagnosis of aip , based on its characteristic histopathology , can only be made using surgically resected tissues , establishing preoperative criteria for aip using biopsy specimens has not been practical .
moreover , kamisawa et al . , reported the possibility that pancreatic cancer may develop in aip patients .
they proposed that k - ras mutations may be frequently detected in aip patients , and aip may be a risk factor for gastric and colonic cancer .
eus - fna cytology improves the diagnosis of pancreatic masses , providing a sensitivity of 80%-90% , a specificity of 95%-100% , and an accuracy of 90%-95% .
eus - fna cytology is often a helpful indicator for determining therapeutic strategies for patients with pancreatic masses , possibly leading to either resection or careful observation in patients in whom diagnosis , resectability , or operability are in question . in our case , the radiology findings suggested either aip or chronic pancreatitis , and only the eus - fna cytology findings indicated pancreatic adenocarcinoma .
thus , eus - fna was a very useful tool for the preoperative differential diagnosis of pancreatic adenocarcinoma and aip .
if patients partially meet the criteria for the diagnosis of aip and/or the mass lesion in the pancreas remains unchanged during steroid therapy , resection should be considered because of the possibility of pancreatic cancer .
even if the cytological findings are negative for malignancy and the patient is diagnosed as having aip , a possible association with adenocarcinoma should be considered .
indeed , our eus - fna findings showed numerous lymphocytes and plasma cells with associated necrosis .
these findings seemed to indicate aip , but atypical epithelial cells were present ; thus , we were able to diagnose the patient as having pancreatic ductal adenocarcinoma accurately .
eus - fna findings may be useful in guiding therapeutic management and may prevent the misdiagnosis of pancreatic tumors .
eus - fna cytology should be further improved to enable pancreatic carcinomas to be distinguished from aip , thereby preventing opportunities for potentially curative resections from being lost while avoiding unnecessary surgical interventions for those with aip . | a 75-year - old man was diagnosed as having pancreatic ductal carcinoma containing remarkable lymphocytic and plasma cell infiltration , as revealed by the cytological examination of endoscopic ultrasound guided fine - needle aspiration ( eus - fna ) specimen .
the eus - fna specimen showed small amounts of atypical epithelium with noticeable lymphocytes and plasma cells .
a pancreatic resection was performed , and the histopathological features showed an invasive pancreatic ductal carcinoma with autoimmune pancreatitis ( aip ) lymphoplasmacytic sclerosing pancreatitis ( lpsp)-like lesions .
most of the plasma cells were immunoreactive to anti - igg4 antibody .
eus - fna may be necessary for the differential diagnosis of aip and pancreatic cancer , and close attention should be given to the presence of marked lymphoplasmacytic cells in eus - fna specimens while making the diagnosis . |
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Email notifications are only sent once a day, and only if there are new matching items. ||||| Hanover Central teacher Travis Lechien was fired, after allegations arose that he gave students alcohol at his home, and took some of them to a strip club. He now faces misdemeanor charges. Kim Vatis reports. (Published Thursday, Oct. 24, 2013)
A northwest Indiana teacher who allegedly took some students to a strip club and gave them alcoholic beverages at his home was terminated Tuesday night, district officials said.
"We take this seriously," Supt. Tom Taylor said of the investigation surrounding Travis Lechien.
Lechien, of Crown Point, faces up to one year in prison on three Class A misdemeanor charges of contributing to the delinquency of a minor. The charges were filed Oct. 7, records show.
The 31-year-old had been suspended without pay from his job as a chemistry teacher at Hanover Central High School since Sept. 10. He was a teacher at the school for 10 years, the Times of Northwest Indiana reported.
Defendant Doesn't Take Stand in Bat Beating Trial
Heriberto Veramontes' lawyers tried to prove their client didn't beat and rob Natasha McShane and Stacy Jurich in April 2010. (Published Thursday, Oct. 24, 2013)
Court documents said Lechien allowed the students to drink beer and other alcoholic beverages at his home and took some of them to a strip club in Hammond to celebrate a student's birthday.
An affidavit states Lechien and the students were pulled over on their way home from the strip club after Lechien, who was driving at the time, was speeding, according to public information officer Patti Van Til with the Lake County Sheriff's Department.
The affidavit also states several students, some 18 and others younger, said they often "hung out" at Lechien's house and sometimes drank beer and hard liquor as well as used flavored tobacco from a hookah the students said belonged to the teacher.
Defense attorney Richard Wolter said he hadn't reviewed the case enough to comment but that Lechien intended to plead not guilty.
Taylor said the incident "puts a stain" on all teachers. ||||| Emailer’s remorse is a very real thing. It can be described as that gut-wrenching feeling one experiences after clicking “send” on an email they’d like to have back. You can’t have it back, though, thus the unease. Once it’s out, it’s permanent. This feeling is commonly the result of writing something regretful to a friend during a harshly-worded exchange amid heightened emotions, or accidentally CC-ing the wrong person in an email about personal business. Rarely does it hit after attaching sexually explicit nudies of yourself to email that was blasted out to an entire class, the very class that you help lead.
Per multiple sources, and currently breaking over Twitter, a teacher assistant at the University of Iowa sent out an email to students of a math class that was intended to assign a homework assignment. The attachment was not a set of math problems, however, but was actually a series of nude photos featuring the female T.A. and a male counterpart — possibly screenshots from a sex video.
breaking news: an Iowa TA accidentally emailed naked pictures of herself to 80+ students instead of sending the study guide #uhoh — Olivia Middleton (@livinthemiddle) October 23, 2013 University of Iowa is the #1 party school and #1 Teacher sextape school #hilarious — Wiley (@Jackwarning) October 23, 2013 Class with the most famous TA in University of Iowa history starts in an hour and a half. Wish me luck! Should I ask for an autograph? — Andrew Merschman (@merschman) October 23, 2013
Andrew Merschman is excited, as I assume many others are around campus. I predict a high attendance rate in this class for the rest of the week. You gotta feel for this poor girl, though. It may be a rough semester for her.
Details are minimal at this point, but we will update this story as they come in.
9:50am CST Update: We obtained a copy of the email. View it below.
10:03am CST Update: We also obtained the nude images. I cannot post them here for obvious reasons. However, I’ll try to describe them for you.
The images are from a video chat that is quite sexual in nature. It appears that two people are “cyber-sexing” from different locations using video equipment. Both are nude and, well, “engaging” themselves in a sexual manner. They appear to be having a grand time. Furthermore, some of the images are in .gif form (short, animated clips).
12:01pm CST Update: The T.A. was back in class this morning trying to play it off like nothing ever happened.
Per tipster:
The TA was teaching her 7:30 discussion session this morning trying to act like nothing happened but clearly very rattled. No one said anything about it but it was just extremely awkward.
Thursday Update: The T.A. is no longer with the class.
In a move that really just had to be made, the teacher assistant has been removed from her position. From KCRG in Iowa:
A University of Iowa teaching assistant who accidentally emailed nude pictures of herself to math students is no longer assigned to their class. University spokesman Tom Moore confirmed the assignment change for the graduate student late Wednesday, but didn’t immediately elaborate.
___
Listen to Roger Dorn discuss this story on Kansas City’s 96.5 The Buzz:
Image via Iowa Now
*** | – Here's an extracurricular activity that won't look so great on your kid's college applications: visiting a strip club with his chemistry teacher. Travis Lechien, 31, was fired from Indiana's Hanover Central High School on Tuesday for allegedly taking teens to a strip club to celebrate a student's birthday, NBC Chicago reports. The ex-teacher also faces jail time; he's been charged with contributing to the delinquency of a minor, the Northwest Indiana Times reports. Additional choice detail No. 1: The affidavit explains that Lechien was pulled over for speeding, with the teens in his car, post-strip club. And No. 2: The students, some younger than 18, also say they "hung out" at Lechien's house frequently, drinking alcohol and smoking from Lechien's hookah. And that's not even this week's only inappropriate teacher story: A University of Iowa teaching assistant accidentally sent nude pictures to students in her math class, the Press-Citizen reports. TotalFratMove.com has a screenshot of the email, which reads, "Hi Class, I attach the solutions for number 76 and 78 in this email." It reports the TA gamely made it to class yesterday morning, "clearly very rattled," which makes sense considering how many people had been discussing the incident on Twitter. University officials are asking students to delete the message and say they are investigating the incident. |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Roadless Area Conservation Act of
2002''.
SEC. 2. FINDINGS AND PURPOSE.
(a) In General.--Congress finds that--
(1) there is a compelling need to establish national
protection for inventoried roadless areas of the National
Forest System in order to protect the unique social and
ecological values of those irreplaceable resources;
(2) roadless areas protect healthy watersheds and their
numerous benefits, such as--
(A) protecting downstream communities from floods
and tempering the effects of drought;
(B) ensuring a supply of clean water for domestic,
agricultural, and industrial uses;
(C) helping maintain abundant and healthy fish and
wildlife populations and habitats;
(D) providing the setting for many forms of outdoor
recreation; and
(E) providing drinking water to millions of
citizens from the more than 354 municipal watersheds
found on roadless areas;
(3) maintaining roadless areas in a relatively undisturbed
condition--
(A) saves downstream communities millions of
dollars in water filtration costs; and
(B) is crucial to preserve the flow of affordable,
clean water to a growing population;
(4) the protection of roadless areas can maintain
biological strongholds and refuges for many imperiled species
by halting the ongoing fragmentation of the landscape into
smaller and smaller parcels of land divided by road corridors;
(5) roadless areas conserve native biodiversity by serving
as a bulwark against the spread of nonnative invasive species;
(6) roadless areas provide unparalleled opportunities for
hiking, camping, picnicking, wildlife viewing, hunting,
fishing, cross-country skiing, canoeing, mountain-biking, and
similar activities;
(7) while roadless areas may have many wilderness-like
attributes, unlike wilderness areas, the use of mechanized
means of travel is allowed in many roadless areas;
(8) roadless areas contain many sites sacred to Native
Americans and other groups that use roadless areas for
spiritual and religious retreats;
(9) from the inception of Federal land management, it has
been the mission of the Forest Service and other agencies to
manage the National Forest System for the dual purposes of
resource extraction and conservation;
(10) consistent with that dual mission, this Act--
(A) protects social and ecological values, while
allowing for many multiple uses of inventoried roadless
areas; and
(B) does not impose any limitations on the use of,
or access to, private, State, or National Forest System
land outside inventoried roadless areas;
(11) establishing a consistent national policy for the
protection of inventoried roadless areas--
(A) ensures that the considerable long-term
ecological and economic benefits of protecting roadless
areas for future generations are properly considered;
(B) diminishes the likelihood of controversy at the
project level; and
(C) enables the Forest Service to focus on the
economic and environmental benefits of reducing
hazardous fuel buildups in already roaded portions of
the landscape;
(12) the National Fire Plan indicates that fires are almost
twice as likely to occur in roaded areas as in roadless areas,
because roadless areas are generally located further away from
communities and are harder to access;
(13) the report entitled ``Protecting People and Sustaining
Resources in Fire-Adapted Ecosystems--A Cohesive Strategy'' (65
Fed. Reg. 67480) advocates a higher priority for fuel reduction
on land that is near communities and readily accessible
municipal watersheds;
(14) the Forest Service has an enormous backlog of
maintenance needs for the existing 386,000 mile road system of
the Forest Service that will cost millions of dollars to
eliminate;
(15) no State or private land owner would continue to build
new roads in the face of such an enormous backlog;
(16) failure to maintain forest roads--
(A) limits public access; and
(B) causes degradation of water quality and
wildlife and fish habitat; and
(17) protection of roadless areas--
(A) will impact less than 0.5 percent of the
national timber supply; and
(B) will have a negligible impact on oil and gas
production since--
(i) the entire National Forest System
provides only approximately 0.4 percent of the
quantity of oil and gas that is produced in the United States; and
(ii) roadless areas provide only a fraction
of the quantity of oil and gas that is produced
in the National Forest System.
(b) Purpose.--The purpose of this Act is to provide, within the
context of multiple-use management, lasting protection for inventoried
roadless areas within the National Forest System.
SEC. 3. DEFINITIONS.
In this Act:
(1) Classified road.--
(A) In general.--The term ``classified road'' means
a road wholly or partially within, or adjacent to,
National Forest System land that is determined to be
needed for long-term motor vehicle access.
(B) Inclusions.--The term ``classified road''
includes a State road, a county road, a privately owned
road, a National Forest System road, and any other road
authorized by the Forest Service.
(2) Inventoried roadless area.--The term ``inventoried
roadless area'' means an area identified in the set of
inventoried roadless area maps contained in the document
entitled ``Forest Service Roadless Area Conservation, Final
Environmental Impact Statement, Volume 2'', dated November
2000, which is on file at the national headquarters office of
the Forest Service, or any subsequent update or revision of
those maps.
(3) Responsible official.--The term ``responsible
official'' means the Forest Service line officer or employee
with the authority and responsibility to make decisions
regarding protection and management of inventoried roadless
areas under this Act.
(4) Road.--The term ``road'' means a motor vehicle
travelway over 50 inches wide, unless designated and managed as
a trail.
(5) Road construction.--The term ``road construction''
means activity that results in the addition of classified road
or temporary road miles.
(6) Road improvement.--The term ``road improvement'' means
activity that results in--
(A) an increase of the traffic service level of an
existing road;
(B) expansion of the capacity of the road; or
(C) a change in the original design function of the
road.
(7) Roadless area characteristics.--The term ``roadless
area characteristics'' means resources or features that are
often present in and characterize inventoried roadless areas,
including--
(A) high quality or undisturbed soil, water, and
air;
(B) sources of public drinking water;
(C) diversity of plant and animal communities;
(D) habitat for--
(i) threatened, endangered, candidate, or
sensitive species, and species proposed for
listing, under the Endangered Species Act of
1973 (16 U.S.C. 1531 et seq.); and
(ii) species dependent on large,
undisturbed areas of land;
(E) primitive, semiprimitive nonmotorized, and
semiprimitive motorized classes of dispersed
recreation;
(F) reference landscapes;
(G) natural appearing landscapes with high scenic
quality;
(H) traditional cultural properties and sacred
sites; and
(I) other locally identified unique
characteristics.
(8) Road maintenance.--The term ``road maintenance'' means
ongoing upkeep of a road necessary to retain or restore the
road in accordance with approved road management objectives.
(9) Road realignment.--The term ``road realignment'' means
an activity that results in--
(A) a new location of all or part of an existing
road; and
(B) treatment of the old roadway.
(10) Road reconstruction.--The term ``road reconstruction''
means an activity that results in improvement, or realignment,
of an existing classified road.
(11) Temporary road.--The term ``temporary road'' means a
road that is--
(A) authorized by contract, permit, lease, other
written authorization, or emergency operation; and
(B) not intended to be part of the forest
transportation system and not necessary for long-term
resource management.
(12) Unclassified road.--The term ``unclassified road''
means a road on National Forest System land that is not managed
as part of the forest transportation system, such as--
(A) an unplanned road, abandoned travelway, or off-
road vehicle track that has not been designated and
managed as a trail; and
(B) a road that was once under permit or other
authorization and was not decommissioned on the
termination of the authorization.
SEC. 4. PROHIBITION ON ROAD CONSTRUCTION AND ROAD RECONSTRUCTION IN
INVENTORIED ROADLESS AREAS.
(a) Prohibition.--Except as provided in subsection (b), road
construction and road reconstruction may not take place in an
inventoried roadless area of the National Forest System.
(b) Exceptions.--Road construction and road reconstruction may take
place, including through the use of appropriated funds, in an
inventoried roadless area of the National Forest System if the
responsible official determines that--
(1) a road is needed to protect public health and safety in
a case of an imminent threat of flood, fire, or other
catastrophic event that, without intervention, would cause the
loss of life or property;
(2) a road is needed to conduct--
(A) a response action under the Comprehensive
Environmental Response, Compensation, and Liability Act
of 1980 (42 U.S.C. 9601 et seq.); or
(B) a natural resource restoration action under--
(i) that Act;
(ii) section 311 of the Federal Water
Pollution Control Act (33 U.S.C. 1321); or
(iii) the Oil Pollution Act of 1990 (33
U.S.C. 2701 et seq.);
(3) a road is needed pursuant to a reserved or outstanding
right, or as provided for by law or treaty;
(4) a road realignment is needed--
(A) to prevent irreparable resource damage that
arises from the design, location, use, or deterioration
of a classified road that cannot be mitigated by road
maintenance; and
(B) to provide for essential public or private
access, natural resource management, or public health
or safety;
(5) road reconstruction is needed to implement a road
safety improvement project on a classified road determined to
be hazardous on the basis of accident experience or accident
potential with respect to the road;
(6)(A) a Federal-aid highway project authorized under title
23, United States Code, is--
(i) in the public interest; or
(ii) consistent with the purposes for which the
land was reserved or acquired; and
(B) no other reasonable and prudent alternative to the
project exists; or
(7)(A) a road is needed in conjunction with--
(i) the continuation, extension, or renewal of a
mineral lease on land that is under lease by the
Secretary of the Interior as of January 12, 2001; or
(ii) the issuance of a new lease issued immediately
on expiration of an existing lease described in clause
(i);
(B) road construction or road reconstruction under this
paragraph will be conducted in a manner that--
(i) minimizes the effects on surface resources;
(ii) prevents unnecessary or unreasonable surface
disturbance; and
(iii) complies with all applicable laws (including
regulations), lease requirements, and land and resource
management plan directives; and
(C) a road constructed or reconstructed under this
paragraph will be removed on the earlier of--
(i) the date on which the road is no longer needed
for the purposes of the lease; or
(ii) the date of termination or expiration of the
lease.
(c) Road Maintenance.--A classified road in an inventoried roadless
area may be maintained.
SEC. 5. PROHIBITION ON TIMBER CUTTING, SALE, OR REMOVAL IN INVENTORIED
ROADLESS AREAS.
(a) Prohibition.--Except as provided in subsection (b), timber may
not be cut, sold, or removed in an inventoried roadless area of the
National Forest System.
(b) Exceptions.--Timber may be cut, sold, or removed in an
inventoried roadless area if the responsible official determines that
the cutting, sale, or removal of the timber is expected to be
infrequent and--
(1) the cutting, sale, or removal of generally small
diameter timber--
(A) will improve or maintain 1 or more roadless
area characteristics; and
(B) is needed--
(i) to improve habitat for threatened,
endangered, candidate, or sensitive species,
and species proposed for listing, under the
Endangered Species Act of 1973 (16 U.S.C. 1531
et seq.); or
(ii) to maintain or restore the
characteristics of ecosystem composition and
structure, such as to reduce the risk of
uncharacteristic wildfire effects, within the
range of variability that would be expected to
occur under a natural disturbance regime of the
current climatic period;
(2) the cutting, sale, or removal of timber is incidental
to the implementation of a management activity not otherwise
prohibited by this Act;
(3) the cutting, sale, or removal of timber is needed and
appropriate for personal or administrative use, in accordance
with part 223 of title 36, Code of Federal Regulations; or
(4) roadless characteristics have been substantially
altered in a portion of an inventoried roadless area as a
result of the construction of a classified road and subsequent
timber harvest, if--
(A) the road construction and subsequent timber
harvest occurred after the area was designated an
inventoried roadless area and before January 12, 2001;
and
(B) timber is cut, sold, or removed only in the
substantially altered portion of the inventoried
roadless area.
SEC. 6. SCOPE AND APPLICABILITY.
(a) Effect.--This Act does not--
(1) revoke, suspend, or modify any permit, contract, or
other legal instrument authorizing the occupancy and use of
National Forest System land issued or entered into before
January 12, 2001;
(2) compel the amendment or revision of any land and
resource management plan;
(3) revoke, suspend, or modify any decision concerning any
project or activity made before January 12, 2001; or
(4) apply to road construction, reconstruction, or the
cutting, sale, or removal of timber in an inventoried roadless
area of the Tongass National Forest if a notice of availability
of a draft environmental impact statement for such activity has
been published in the Federal Register before January 12, 2001.
(b) Limitation on Revision.--The prohibitions and restrictions
established in this Act are not subject to reconsideration, revision,
or rescission in any subsequent project decision or amendment or
revision to any land and resource management plan carried out in
accordance with section 6 of the Forest and Rangeland Renewable
Resources Planning Act of 1974 (16 U.S.C. 1604). | Roadless Area Conservation Act of 2002 - Prohibits road construction and road reconstruction in inventoried roadless areas of the National Forest System. Specifies exceptions, including because: (1) there is threat of a catastrophic event; (2) a natural resource restoration action is necessary; or (3) a Federal-aid highway project is in the public interest or is consistent with the purposes for which the land was reserved or acquired.Forbids timber from being cut, sold, or removed in an inventoried roadless area. Permits various exceptions, including for specified environmental reasons, if the responsible official determines that the cutting, sale, or removal of timber is expected to be infrequent.Declares that this Act does not: (1) revoke, suspend, or modify legal instruments and decisions concerning the use of NFS land made before January 12, 2001; (2) compel the amendment or revision of any land and resource management plan; or (3) apply to specified activities in the Tongass National Forest.States that the prohibitions and restrictions of this Act cannot be reconsidered, modified, or terminated under the Forest and Rangeland Renewable Resources Planning Act of 1974. |
the stomach is a central metabolic crossroad wherein numerous signals converge and depart to control nutrient intake , appetite , and general metabolic homeostasis .
thus , data gleaned over the last few years have shown that the stomach plays a key role in the regulation of food intake through the secretion of peptides such as ghrelin .
in addition , gastric emptying through the regulation of gastric distension also influence the rate of intestinal exposure of nutrients thereby influencing the secretion of a vast array of gastrointestinal hormones which in turn also control food intake and/or energy expenditure .
therefore , the stomach has emerged as a key organ in the regulation of body weight homeostasis , and gastric surgery is at the front line of treatment of patients with morbid obesity .
however , there is a general lack of knowledge on the adaptation process that take part in the stomach in relation to energy balance .
we felt the critical question pending was to identify the subcellular events that take place in this tissue and its relationship to alterations in energy balance .
disulfide isomerase glucose - regulated protein 58 ( also known as , grp58 , erp57 , er-60 , erp60 , erp61 ) is a molecular chaperone member of the er - stress signaling pathway . specifically , grp58 is a 58 kda thiol - disulfide oxidoreductase protein , physiologically involved in the folding catalysts modification of disulfide bonds in glycoprotein [ 3 , 4 ] , and has been previously identified in the stomach as a marker for human gastric cancer .
moreover , it is also highly expressed in liver , placenta , and lung , and weakly expressed in other tissues . in vitro and in vivo studies
have shown that grp58 protein acts on glycosylated substrates through the er resident lectins - calnexin and the calreticulin system to catalyze the isomerization or exchange of disulfide bonds [ 6 , 7 ] .
grp58 substrates share common properties : they are glycoprotein , heavily disulfide bonded , and likely to form nonnative disulfide bonds [ 6 , 7 ] .
most of these substrates contain abundant domains of cysteine residues , which usually promote formation of the disulfide bonds during glycoprotein folding [ 68 ] . in line with the interrelation among metabolism , er - stress and chaperone function
, it has been shown that grp58 expression is induced by different stress conditions , such as glucose deprivation or hypoxia [ 9 , 10 ] .
furthermore , hepatic grp58 was phosphorylated after 12-h/24-h fasting and after leptin treatment , and interacts with the jak - stat signaling pathway implicated in the intracellular signal transduction of leptin .
although grp58 is a marker for human gastric cancer , few studies have addressed the regulation and potential role of er - stress , and in particular that of grp58 , in gastric function .
our results demonstrate that grp58 is expressed in rat gastric and reveal that gastric grp58 mrna expression and dephosphorylation are increased after leptin treatment . therefore , our results suggest that gastric grp58 might play an important role in the regulation of energy homeostasis .
adult male sprague dawley rats ( 250300 g , 810 weeks old ) were bred in the animalario general usc ; university of santiago de compostela , spain , and male leptin - deficient mice ( 8 weeks old ) were purchased from charles river , barcelona , spain .
animals were housed in open cages under conditions of controlled illumination ( 12-hour light / dark schedule ) , humidity , and temperature .
the animals were sacrificed by decapitation in a room separate from other experimental animals in the afternoon ( 16:00 - 17:00 h ) . the gastric mucosa was then collected and frozen at 80c until analysis .
all experiments were conducted in accordance with the european union laws on protection regarding laboratory animals after previous approval by the ethics committee of the university of santiago de compostela , spain ( permit number : pgidit06pxib208063pr ) .
animal groups ( n = 8 per group ) were deprived of food for 48 h while the control group was fed ad libitum .
all animals had free access to tap water . gastric mucosa was rapidly dissected and stored at 80c until proteomic and mrna analyses were performed .
we next investigated whether leptin affects gastric mucosa grp58 mrna expression and modifications in the protein phosphorylation pattern shift .
rats and mice were assigned to one of the following groups ( n = 8 per group ) : ( a ) i.p . vehicle fed ad libitum ; ( b ) i.p .
animals were treated with recombinant leptin ( l-4146 , sigma - aldrich ) at a dose of 0.8 g / kg of body weight every 12 h for 3 days ( intraperitoneal injection ) as described elsewhere . for the proteomic
setting , we treated rats with leptin at short term : 6 h and 24 h before the sacrifice with a single intraperitoneal injection ( 0,8 g / kg of body weight in a volume of 0.25 ml ) .
the reason we carried out this short - term experiment for proteomic approaches is that the pattern shift of phosphorylation / dephosphorylation is commonly faster than changes at transcriptional level .
western blot analysis from 1d and 2d gels were performed as described elsewhere . briefly , gastric mucosa proteins were resolved by polyacrylamide gel electrophoresis according to the method described below and transferred to nitrocellulose membrane ( hybond c - super , amersham pharmacia biotech ) .
santa cruz biotechnology , santa cruz , ca , usa ) and alpha - tubulin ( sigma ; poole , uk ) .
the membranes after incubation with respective secondary antibodies were probed with hrp - conjugated secondary antibodies and the signal was developed with chemiluminescence reagents ( tropix , bedford ; ma , usa ) and exposed to x - ray film .
gastric mucosa was lysed at 4c using a tissue homogenizator ( omni tissuemaster-125 homogenizers ) .
lysates were prepared in lysis buffer ( 7 m urea , 2 m thiourea , 4% chaps , 5 mm magnesium acetate , 20 mmtris hcl ph 8.5 , 0.2% ampholytes w / v , and bromophenol trace ) .
samples were centrifuged at 15000 g under 4c during 15 min to remove the debris as described previously .
first dimension isoelectric focusing was performed with the horizontal multiphor ipgphor iii system ( ge healthcare , formerly amersham biosciences ) ; using 11 cm ipg strips ( ph 47 , ge healthcare ) . the sample ( 50 g ) was dissolved by soaking in 200 l of rehydration buffer ( 7 m urea , 2 m thiourea , 4% chaps and bromophenol trace ) during 8 hours .
then , it was loaded onto an 11 cm - linear range with ph 47 immobilized gradient strip ( 4 gels per experimental group and each one originated from different animals ) and isoelectric focusing was performed as recommended by the manufacturer , ramping the voltage subsequently applied to reach 6000 vht .
the strips containing focused proteins were thawed , equilibrated , and reduced in equilibration buffer ( 6 m urea , 50 mm m tris - cl ph 8.8 , 2% sds , 30% glycerol , and 2% ( w / v ) dtt ) during 15 min , then alkylated in equilibration buffer ( 6 m urea , 50 mm tris - cl ph 8.8 , 30% glycerol , 2% sds , 2.5% ( w / v ) iodoacetamide .
equilibrated strips were transferred to a sds - page gel ( 10% ) , secured in place by molten agarose and subjected to electrophoresis ( mini - protean tetra cell ; bio - rad laboratories ) .
afterwards , electrophoresis gels were stained using plusone silver staining kit , protein ( ge healthcare ) , as recommended by the manufacturer protocols .
spots were excised automatically in a propic station ( genomic solutions , uk ) and digested with modified porcine trypsin ( sequencing grade ; promega ) , by using a progest digestion station ( genomic solutions , u.k . ) .
the gel specimens were destained twice over 30 min at 37c with 200 mm ammonium bicarbonate/40% acetonitrile .
gel pieces were then subjected to three consecutive dehydratation / rehydratation cycles with pure acetonitrile and 25 mm ammonium bicarbonate in 50% acetonitrile , respectively , and finally dehydrated for 5 min with pure acetonitrile and dried out over 4 h at room temperature .
then , 20 l trypsin , at a concentration of 12.5 ng/l in 25 mm ammonium bicarbonate was added to the dry gel pieces and the digestion proceded at 37c for 12 h. peptides were extracted from gel plugs by adding 1 l of 10% ( v / v ) trifluoracetic acid ( tfa ) and incubating for 15 min .
then , they were desalted and concentrated by using c-18 ziptip columns ( millipore ) in a proms station ( genomic solutions , u.k . ) and directly loaded onto the maldi plate using -cyano hydroxycinnamic acid as the matrix .
mass analysis of peptides of each sample were performed with a maldi - tof / tof ( 4700 proteomics analyzer , applied biosystems , usa ) in automatic mode with the following setting : for the ms data , m / z range 800 to 4000 with an accelerating voltage of 20 kv and delayed extraction , peak density of maximum 50 peaks per 200 da , minimal s / n ratio of 10 and maximum peak at 65 .
spectra were internally calibrated with peptides from trypsin autolysis ( m + h+ = 842.509 , m + h+ = 2211.104 ) . for the ms / ms data
, mass range was set between 60 da and 10 da below each precursor mass , with a minimum s / n ratio of 5 , a maximum number of peak set at 65 and peak density of maximum 50 peaks per 200 da .
proteins were assigned identification by peptide mass fingerprinting and confirmed by ms / ms analysis .
mascot 2.0 search engine ( matrix science , u.k . ) was used for protein identification running on gps software ( applied biosystems ) over the national center for biotechnology information ( ncbi ) protein database ( updated monthly ) .
search setting allowed one missed cleavage with the selected trypsin enzyme , an ms / ms fragment tolerance of 0.2 da and a precursor mass tolerance of 100 ppm .
proteins with a statistically significant ( p < 0.05 ) were positively assigned identification after considering mr and pi values . total rna from gastric mucosa
was extracted using trizol ( invitrogen , inc . ) according to the manufacturer 's instructions .
rna was reverse transcribed and the resulting cdna was synthesized from 2 ug total rna by random priming rt .
the resulting cdna was subjected to pcr amplification as described at [ 13 , 16 ] using sense and antisense primers specific for the rat grp58 and the housekeeping gene hypoxanthine guanine phosphoribosyltransferase ( hprt ) mrnas ( table 1 ) . for real - time semiquantitative analysis we used the applied biosystems 7500 real - time pcr system ( applied biosystems , ca , usa ) , as previously described [ 1315 ] .
rat grp58 and 18s ribosomal rrna relative gene expression quantification was made using specific primers and taqman fluorescent probes for these target genes , and the sequences are described in table 1 .
the results are shown as the means sem ( standard error of the mean ) and analyzed by using graphpad instat 3.05 ( graphpad software , inc . ) software . statistical significance was determined by student 's t - test when two groups were compared . in the experiments constituted by three groups
the data were analyzed by one - way anova followed by a post hoc multiple comparison test ( bonferroni test ) .
expression of the mrna encoding grp58 gene ( figure 1 ) was evaluated by rt - pcr and compared to housekeeping gene hprt .
this analysis demonstrates the expression of the message of the gene in male rat liver and gastric mucosa whereas its expression was not found in tissues such as pancreas and brain ( figure 1 ) . after discovering that grp58 is expressed in the gastric mucosa by means of rt - pcr
, we employed western blot analysis to determine whether the message is translated into protein . using a specific primary antibody for grp58
, we detected a major band in protein extracts of rat gastric , and observed that protein levels of grp58 were decreased after 24 h and 48 h of fasting ( figure 2 ) .
moreover , in the gastric mucosa of rats fasted during 48 h , we found that the band had a lower molecular weight , likely suggesting a dephosphorylation ( figure 2 ) . to test the hypothesis that grp58 was dephosphorylated during fasting
representative 2-de gel images of rat gastric tissue with differential expressed protein in fed state ( figure 3(a ) ) compared to fasted state ( figure 3(b ) ) . differentially expressed protein spots ( marked with letters ) were picked , digested with trypsin , and analyzed by peptide mass fingerprinting as previously described ( tables 2 and 3 ) [ 17 , 18 ] .
the peptide mass fingerprints were acquired by mass spectrometry using a matrix - assisted laser desorption / ionization time - of - flight ( maldi - tof ) .
all analyzed spots correspond to multiple phosphorylated forms of grp58 protein , which were identified by the comparison of peptide mass fingerprint data generated by maldi - tof mass spectrometry against theoretically digested homo sapiens , swiss - prot and trembl database , and by the use of mascot software . among the identified protein spots ,
a 4-protein series with identical molecular weight of approximately 58 kda and different isoelectric points were identified as grp58 .
the identified phosphorylated forms of grp58 protein in rat gastric along with referred data are listed in table 3 .
these phosphorylation profile shifts were identified through a 2-de western blot analysis using an anti - grp58 antibody , recognizing four immunoreactive protein spots ( figures 4(a ) and 4(b ) ) that showed a basic shifted signal in the profile of grp58 .
additionally , using 2de , we found that 48 h of fasting dephosphorylated gastric mucosa grp58 in comparison with rats fed ad libitum ( figure 5 ) .
when 48 h fasted - rats were treated with leptin for 6 hours or 24 h , we observed that the fasting - induced grp58 dephosphorylation was blunted ( figure 5 ) .
therefore , our results indicate that the dephosphorylation of gastric mucosa grp58 induced by fasting , a hypoleptinemic state , is likely mediated by circulating leptin levels .
we then measured the mrna expression of gastric mucosa grp58 in the same experimental paradigm described above , meaning , fed ad libitum , fasted , and fasted leptin - treated rats .
we failed to detect any significant change in the gene expression of grp58 of fasted rats when compared to feed ad libitum rats ( figure 6(a ) ) .
however , we found that leptin treatment was able to trigger gastric mucosa grp58 mrna levels in fasted rats in comparison with vehicle - treated rats ( figure 6(a ) ) .
similar results were detected in fed ad libitum rats , which showed a clear upregulation in grp58 gene expression after the leptin treatment ( figure 6(b ) ) . according to pharmacological data , the endogenous lack of leptin downregulated gastric mucosa grp58 gene expression when compared to wild - type mice ( figure 6(c ) ) . finally , when leptin - deficient mice were fasted for 48 h we failed to detect changes in grp58 mrna levels , but when those fasted mice were treated with exogenous leptin , an increase in gastric mucosa grp58 gene expression was found ( figure 6(d ) ) .
overall , our findings show that leptin is an important mediator of grp58 gene expression in the gastric mucosa .
the endoplasmic reticulum ( er ) is a multifunctional organelle that plays a critical role in multiple cellular processes including , among others , protein and lipid biosynthesis , steroid production , calcium homeostasis , and carbohydrate metabolism .
in addition , the er contains a large number of calcium - dependent molecular chaperones and folding enzymes , which are physiologically responsible for several cotranslational and posttranslational modifications [ 22 , 23 ] .
alterations in energy metabolism including glucose / energy deprivation , oxidative injury , hypoglycemia , hypoxia , and high - fat diet impair er homeostasis .
more specifically , nutritional excess induces er stress in subcutaneous adipose tissue of obese human subjects .
additionally , er stress has been related to the development of atherosclerosis and diabetes [ 2427 ] .
for instance , obese humans and rodents develop er stress in liver and adipose tissues , leading to insulin resistance whereas weight - loss decreases er stress and improves insulin sensitivity , suggesting a correlation between er stress and the metabolic syndrome [ 27 , 28 ] . by using proteomics analysis , we found evidence of a grp58 phosphorylation / dephosphorylation pattern shift in the rat gastric under changes in nutritional status . more specifically , using the 2de gel methodology and peptide mass fingerprinting - protein identification by means of maldi - tof mass spectrometry
, we show that gastric mucosa grp58 is dephosphorylated by fasting , and this effect is blunted when fasted rats are treated with leptin .
grp58 , a well - known stress protein , has been previously identified in the stomach as a marker for human gastric cancer .
furthermore , previous works have demonstrated the presence of leptin and leptin receptor in the stomach , suggesting that gastric mucosa cells may be targets for leptin [ 29 , 30 ] .
grp58 and signal transducer and activator of transcription 3 ( stat3 ) , an essential signaling molecule mediating the biological actions of leptin , have been localized in both the cytoplasm and nucleus [ 32 , 33 ] . in this regard
, some studies have shown that grp58 may be implicated in the transcriptional control of stat3 [ 12 , 32 ] .
notwithstanding the evidence mentioned above , there was a general lack of knowledge regarding a potential role of gastric grp58 in metabolism .
concurring with a role of gastric grp58 on energy balance , we demonstrate that leptin induces , whereas leptin - deficiency reduces , gastric mucosa grp58 mrna expression , suggesting that leptin modulates both grp58 phosphorylation and expression . since these effects seem to be nutritional , it is plausible to hypothesize that other tissues that are target of leptin action in nutritional context like the intestine might be also involved in the regulation of grp58 .
for instance , leptin is expressed and secreted by inflamed colonic epithelial cells , it may act as a growth factor in colon tissue .
thus , the role of leptin on grp58 throughout the entire gastrointestinal tract deserves further investigation .
our findings obtained in rat gastric differ from data obtained in the rat liver , where it was found that serine 150 of grp58 was phosphorylated by both fasting and leptin .
thereby , those results were indicating that nutritional - induced changes in liver grp58 phosphorylation were not mediated by circulating leptin levels . our current data demonstrating that leptin blocks the fasting - induced dephosphorylation of gastric grp58 suggest that changes in the activity of this protein are modulated by nutritional status .
importantly , leptin seems to be responsible for those nutritional - induced changes in gastric grp58 phosphorylation .
moreover , the different results obtained in the pattern of grp58 phosphorylation in the liver and the stomach suggests that grp58 is regulated by nutritional status in a tissue - specific manner . since we have detected multiple phosphorylated forms of grp58 protein in the gastric mucosa ( figure 2 ) , we hypothesize that these phosphorylated forms could contribute to the tissue - specific regulation of grp58 in response to fasting and leptin treatment .
first , the functional role of phosphorylation / dephosphorylation of grp58 caused by physiological and physiopathological conditions is largely unknown .
second , the sites of phosphorylation / dephosphorylation of grp58 are different in each tissue [ 11 , 37 ] , so it might be possible that the grp58 phosphorylated forms that we detected in the gastric mucosa also have different phosphorylation sites .
third , the factors that induce these phosphorylation / dephosphorylation shifts in a tissue - specific manner are mostly unknown .
all these issues seem relevant to elucidate the precise role and mechanisms mediating grp58 actions in the organism .
in addition to the actions of nutritional status on the pattern of gastric mucosa grp58 phosphorylation , we have also assessed the regulation of grp58 gene expression .
our findings indicate that leptin increases grp58 mrna expression whereas leptin deficiency decreases the levels of this protein . since leptin lowers blood glucose levels and leptin - deficient mice
are hyperglycemic , our results are in agreement with previous in vitro results indicating that grp58 expression is induced by glucose deprivation .
although grp58 mrna expression remained unchanged after fasting , we found that its protein levels were decreased after 24 h and 48 h of fasting .
therefore , it is likely that the actions of leptin on grp58 are dependent of nutritional status . on the other hand
, the ingestion of specific components of the diet like fructose increases the secretion of gastric leptin , and this might also affect grp58 gastric levels
. taken together , our findings obtained on the dephosphorylation and total mrna expression of grp58 indicate that leptin regulates the phosphorylation and expression of gastric grp58 in rats
. it also seems reasonable to hypothesize that at least some of the actions of leptin at the gastric level might be mediated by grp58 . in conclusion ,
our results demonstrate that grp58 phosphorylation responds rapidly to changes in dietary energy and leptin treatment , and thereby support that grp58 can play an important physiological role in the signaling pathways related to energy balance in the stomach .
more precisely , our findings indicate that ( a ) fasting dephosphorylates gastric mucosa grp58 , ( b ) leptin blunts fasting - induced grp58 dephosphorylation , and ( c ) leptin stimulates gastric mucosa mrna expression .
dissection of the molecular pathways mediating the interactions between er stress - related factors and nutrient availability , as well as their target genes may open a new avenue for the study of obesity and other metabolic disorders . | the stomach secretes a wide range of peptides with essential metabolic functions , and thereby plays an important role in the regulation of energy homeostasis .
disulfide isomerase glucose - regulated protein 58 ( grp58 ) is a molecular chaperone member of the endoplasmic reticulum ( er ) stress signaling pathway , which is a marker for human gastric cancer .
since grp58 seems to be regulated by a phosphorylation / dephosphorylation pattern shift , we used the 2de gel methodology and peptide mass fingerprinting - protein identification by means of maldi - tof mass spectrometry .
we show that gastric mucosa grp58 is dephosphorylated by fasting , and this effect is blunted when fasted rats are treated with leptin .
furthermore , we assessed the gene expression of grp58 under different physiological settings known to be associated with energy homeostasis ( fasting , leptin treatment and leptin deficiency ) .
we found that intraperitoneal administration of leptin increases whereas leptin deficiency decreases grp58 mrna levels .
however , grp58 expression remains unchanged after fasting , indicating that leptin actions on grp58 are no direct sensitivity to fasting .
dissection of the molecular pathways mediating the interactions between er stress - related factors and nutrient availability , as well as their target genes , may open a new avenue for the study of obesity and other metabolic disorders . |
we employed an empirical model of the relationship between climate and dengue based on the known global distribution of dengue ( 12 ) . the climate factor that predicts the presence of dengue most accurately is the long - term average humidity of a region , expressed as average annual vapour pressure , which is an expression of both humidity and temperature .
mosquito survival is strongly dependent on moisture and humidity levels ; longer mosquito lifespans increase the likelihood of multiple blood feeds and hence transmission of dengue .
warmer temperatures also facilitate dengue transmission through speeding up replication rate of the virus within the vector , reducing the extrinsic incubation period and thus time to infectivity .
the model does not attempt to predict the current or potential geographic range of the vector itself , which may extend beyond regions where virus transmission is currently observed .
we used this climate - disease relationship to model the regions in australia that are at high risk of becoming suitable for dengue transmission under four different climate change scenarios ( box 1 ) . from annual average vapour pressure and temperature baseline data for each statistical division ( sd ) ( 13 ) for the period 19611990 ( 14 ) , we calculated relative humidity by using standard meteorological conversion formulae .
we calculated the probability that one ( or more ) epidemics of dengue fever could occur , defining regions to be at risk of dengue where the model indicated a greater than 50% probability of transmission .
the four climate scenarios used were produced by australia 's commonwealth scientific and industrial research organisation ( csiro ) for the australian government 's garnaut climate change review ( 15 ) .
three of the scenarios assume no action is taken to reduce emissions ; emissions remain high and continue to rise , mean global temperature increase is around 4.5c by 2100 .
strong action is taken ; emissions are significantly reduced over coming decades , co2 stabilises at 420 ppm by 2100 , and mean global temperature increase is around 2c .
we estimated the future population at risk using population projections for each sd in the national census data ( 16 , 17 ) .
we obtained the estimates for the capital cities and rest - of - state areas for each state and territory between 2004 and 2100 .
the capital city estimates from this dataset were used for the entire period ; the rest - of - state estimates were adjusted to reflect predicted trends in the sds within them . for this we used an earlier set of sd population predictions from 2004 to 2019 ( 18 ) to interpolate sd populations from 2020 to 2049 to the australian bureau of statistics ( abs ) estimate for 2050 ( 19 , 20 ) . in the absence of sub - state level projections from the abs from 2050 to 2100
, we made the simplifying assumption that the proportional contribution each sd made to the rest - of - state totals up to 2050 would remain for the rest of the century . on this basis , we estimated the rest - of - state population totals for the period 2051 and 2100 , taking the abs 2100 values as the endpoint . to estimate numbers of annual infections in the future ,
a minimum expected average annual incidence of dengue infection was derived from baseline using notifications between 1991 and 2007 ( 10 , ( scott ritchie , far north queensland health service , personal communication ) ) ( i.e. not including the most recent and unusual 20082009 epidemic ) and population resident in the at risk region .
an upper incidence estimate for future infections was derived from numbers of infections during the most recent outbreak ( n.b .
even this upper estimate is conservative as it does not take into account likely changing transmission intensity in the future ) .
regular donors from each state to estimate future percentage declines in national blood supply based on modelled dengue transmission areas , population at risk and projected incidence of infection .
this current pattern of blood donation by state was estimated from a recent national survey of over 2,000 adults ( methods described elsewhere ( 21 ) ) where response was usually donate at least every six months. we estimated that the annual public health and health care cost of dengue is approximately $ 2.82 per person living in transmission - risk areas .
this is comprised of :
surveillance and control : $ 2.56 per person , for vector surveillance and control , health education , case ascertainment and follow - up , and training of specialist staff ( scott ritchie , far north queensland health , personal communication ) .
approximately three times the number of diagnostic tests are conducted for dengue and associated viruses as the number of confirmed tests .
routine testing during the year might results in another 50 tests being conducted 650 in all .
approximately half these are pcr ( @$75 ) and the other half igm elisa ( @$180 ) ( ( scott ritchie , far north queensland health service , personal communication ) , ( russell simmons , queensland health scientific services , personal communication)).treatment costs : 7c per person , from an average of two visits to a general practitioner ( one to seek a test , and another to get the results ) and additional follow - up checks for approximately 10% of cases . a standard level b general practice consultation is $ 55 .
assuming all confirmed cases and 50% of unconfirmed cases attend a general practice 2.1 times in an average year , this makes 546 visits at baseline at a cost of approximately $ 30,000 ( scott ritchie , far north queensland health service , personal communication).hospital costs : deaths to date have been rare and generally occur before protracted hospital stays incur notable system costs.time off work due to dengue illness or caring for a sick child is an additional economic cost that we have estimated previously ( 1 ) to be 0.005 days per year per person living in a dengue transmission region .
surveillance and control : $ 2.56 per person , for vector surveillance and control , health education , case ascertainment and follow - up , and training of specialist staff ( scott ritchie , far north queensland health , personal communication ) .
diagnostic costs : 19c per person .
approximately three times the number of diagnostic tests are conducted for dengue and associated viruses as the number of confirmed tests .
routine testing during the year might results in another 50 tests being conducted 650 in all .
approximately half these are pcr ( @$75 ) and the other half igm elisa ( @$180 ) ( ( scott ritchie , far north queensland health service , personal communication ) , ( russell simmons , queensland health scientific services , personal communication ) ) .
treatment costs : 7c per person , from an average of two visits to a general practitioner ( one to seek a test , and another to get the results ) and additional follow - up checks for approximately 10% of cases . a standard level b general practice consultation is $ 55 .
assuming all confirmed cases and 50% of unconfirmed cases attend a general practice 2.1 times in an average year , this makes 546 visits at baseline at a cost of approximately $ 30,000 ( scott ritchie , far north queensland health service , personal communication ) .
hospital costs : deaths to date have been rare and generally occur before protracted hospital stays incur notable system costs .
we employed an empirical model of the relationship between climate and dengue based on the known global distribution of dengue ( 12 ) . the climate factor that predicts the presence of dengue most accurately is the long - term average humidity of a region , expressed as average annual vapour pressure , which is an expression of both humidity and temperature .
mosquito survival is strongly dependent on moisture and humidity levels ; longer mosquito lifespans increase the likelihood of multiple blood feeds and hence transmission of dengue .
warmer temperatures also facilitate dengue transmission through speeding up replication rate of the virus within the vector , reducing the extrinsic incubation period and thus time to infectivity .
the model does not attempt to predict the current or potential geographic range of the vector itself , which may extend beyond regions where virus transmission is currently observed .
we used this climate - disease relationship to model the regions in australia that are at high risk of becoming suitable for dengue transmission under four different climate change scenarios ( box 1 ) . from annual average vapour pressure and temperature baseline data for each statistical division ( sd ) ( 13 ) for the period 19611990 ( 14 ) , we calculated relative humidity by using standard meteorological conversion formulae .
we calculated the probability that one ( or more ) epidemics of dengue fever could occur , defining regions to be at risk of dengue where the model indicated a greater than 50% probability of transmission .
the four climate scenarios used were produced by australia 's commonwealth scientific and industrial research organisation ( csiro ) for the australian government 's garnaut climate change review ( 15 ) .
three of the scenarios assume no action is taken to reduce emissions ; emissions remain high and continue to rise , mean global temperature increase is around 4.5c by 2100 .
strong action is taken ; emissions are significantly reduced over coming decades , co2 stabilises at 420 ppm by 2100 , and mean global temperature increase is around 2c .
we estimated the future population at risk using population projections for each sd in the national census data ( 16 , 17 ) .
we obtained the estimates for the capital cities and rest - of - state areas for each state and territory between 2004 and 2100 .
the capital city estimates from this dataset were used for the entire period ; the rest - of - state estimates were adjusted to reflect predicted trends in the sds within them . for this we used an earlier set of sd population predictions from 2004 to 2019 ( 18 ) to interpolate sd populations from 2020 to 2049 to the australian bureau of statistics ( abs ) estimate for 2050 ( 19 , 20 ) . in the absence of sub - state level projections from the abs from 2050 to 2100
, we made the simplifying assumption that the proportional contribution each sd made to the rest - of - state totals up to 2050 would remain for the rest of the century . on this basis , we estimated the rest - of - state population totals for the period 2051 and 2100 , taking the abs 2100 values as the endpoint . to estimate numbers of annual infections in the future ,
a minimum expected average annual incidence of dengue infection was derived from baseline using notifications between 1991 and 2007 ( 10 , ( scott ritchie , far north queensland health service , personal communication ) ) ( i.e. not including the most recent and unusual 20082009 epidemic ) and population resident in the at risk region .
an upper incidence estimate for future infections was derived from numbers of infections during the most recent outbreak ( n.b .
even this upper estimate is conservative as it does not take into account likely changing transmission intensity in the future ) .
regular donors from each state to estimate future percentage declines in national blood supply based on modelled dengue transmission areas , population at risk and projected incidence of infection .
this current pattern of blood donation by state was estimated from a recent national survey of over 2,000 adults ( methods described elsewhere ( 21 ) ) where response was usually donate at least every six months.
we estimated the future population at risk using population projections for each sd in the national census data ( 16 , 17 ) .
we obtained the estimates for the capital cities and rest - of - state areas for each state and territory between 2004 and 2100 . the capital city estimates from this dataset were used for the entire period ; the rest - of - state estimates were adjusted to reflect predicted trends in the sds within them . for this we used an earlier set of sd population predictions from 2004 to 2019 ( 18 ) to interpolate sd populations from 2020 to 2049 to the australian bureau of statistics ( abs ) estimate for 2050 ( 19 , 20 ) . in the absence of sub - state level projections from the abs from 2050 to 2100 , we made the simplifying assumption that the proportional contribution each sd made to the rest - of - state totals up to 2050
would remain for the rest of the century . on this basis , we estimated the rest - of - state population totals for the period 2051 and 2100 , taking the abs 2100 values as the endpoint . to estimate numbers of annual infections in the future ,
a minimum expected average annual incidence of dengue infection was derived from baseline using notifications between 1991 and 2007 ( 10 , ( scott ritchie , far north queensland health service , personal communication ) ) ( i.e. not including the most recent and unusual 20082009 epidemic ) and population resident in the at risk region .
an upper incidence estimate for future infections was derived from numbers of infections during the most recent outbreak ( n.b .
even this upper estimate is conservative as it does not take into account likely changing transmission intensity in the future ) .
regular donors from each state to estimate future percentage declines in national blood supply based on modelled dengue transmission areas , population at risk and projected incidence of infection .
this current pattern of blood donation by state was estimated from a recent national survey of over 2,000 adults ( methods described elsewhere ( 21 ) ) where response was usually donate at least every six months.
we estimated that the annual public health and health care cost of dengue is approximately $ 2.82 per person living in transmission - risk areas .
this is comprised of :
surveillance and control : $ 2.56 per person , for vector surveillance and control , health education , case ascertainment and follow - up , and training of specialist staff ( scott ritchie , far north queensland health , personal communication ) .
approximately three times the number of diagnostic tests are conducted for dengue and associated viruses as the number of confirmed tests .
routine testing during the year might results in another 50 tests being conducted 650 in all .
approximately half these are pcr ( @$75 ) and the other half igm elisa ( @$180 ) ( ( scott ritchie , far north queensland health service , personal communication ) , ( russell simmons , queensland health scientific services , personal communication)).treatment costs : 7c per person , from an average of two visits to a general practitioner ( one to seek a test , and another to get the results ) and additional follow - up checks for approximately 10% of cases . a standard level b general practice consultation is $ 55 . assuming all confirmed cases and 50% of unconfirmed cases attend a general practice 2.1 times in an average year
, this makes 546 visits at baseline at a cost of approximately $ 30,000 ( scott ritchie , far north queensland health service , personal communication).hospital costs : deaths to date have been rare and generally occur before protracted hospital stays incur notable system costs.time off work due to dengue illness or caring for a sick child is an additional economic cost that we have estimated previously ( 1 ) to be 0.005 days per year per person living in a dengue transmission region .
surveillance and control : $ 2.56 per person , for vector surveillance and control , health education , case ascertainment and follow - up , and training of specialist staff ( scott ritchie , far north queensland health , personal communication ) .
diagnostic costs : 19c per person .
approximately three times the number of diagnostic tests are conducted for dengue and associated viruses as the number of confirmed tests .
routine testing during the year might results in another 50 tests being conducted 650 in all .
approximately half these are pcr ( @$75 ) and the other half igm elisa ( @$180 ) ( ( scott ritchie , far north queensland health service , personal communication ) , ( russell simmons , queensland health scientific services , personal communication ) ) .
treatment costs : 7c per person , from an average of two visits to a general practitioner ( one to seek a test , and another to get the results ) and additional follow - up checks for approximately 10% of cases .
a standard level b general practice consultation is $ 55 . assuming all confirmed cases and 50% of unconfirmed cases attend a general practice 2.1 times in an average year , this makes 546 visits at baseline at a cost of approximately $ 30,000 ( scott ritchie , far north queensland health service , personal communication ) .
hospital costs : deaths to date have been rare and generally occur before protracted hospital stays incur notable system costs .
under each of the three no emissions action scenarios , there is an increase in the geographic spread and hence the number of sds that are favourable to dengue transmission ( fig .
, the geographic region suitable for the transmission of dengue is expected to extend far to the south and west from its current distribution .
the regions at risk include all coastal areas of queensland and into new south wales , northern western australia and the northern territory . in scenarios 1 ( hot and dry ) and 2 ( hot , median humidity ) , dengue transmission areas extend south in queensland to include brisbane ( and west to mt isa in scenario 2 ) , and into broome in western australia .
in contrast , under emissions mitigation ( the strong action scenario 4 ( warm ) ) , dengue transmission - suitable areas remain limited to northern queensland and to darwin .
areas suitable in australia for dengue transmission in 2100 under four climate change scenarios ( > 50% likelihood of transmission ) .
the number of people at risk from dengue ( i.e. the population living in transmission - risk areas ) estimated under each scenario in coming decades is shown in fig . 3 , and
the percentage changes are represented in table 1 . the number of people living in regions in australia at high risk ( > 50% ) of dengue transmission under four climate change scenarios .
scenarios : 1 , hot ( dry ) ; 2 , hot ( median humidity ) ; 3 , hot ( wet ) ; 4 , warm ( strong mitigation ) .
percentage change in numbers of people living in transmission - risk areas , selected years annual rates of confirmed infection are estimated to be between 47/100,000 and 230/100,000 in dengue susceptible regions , with a further 28/100,000138/100,000 sub - clinical infections likely .
table 2 shows the range estimate for the number of people to be infected with dengue based on the exposed population and these current rates of infection .
estimated annual numbers of new dengue infections under the four climate scenarios
using population at risk projections ( fig .
lower estimate is calculated from average annual incidence rate 19912007 ; upper estimate is calculated from the much larger 20082009 outbreak . note .
these upper estimates are likely to be conservative in a climate changed future as they do not consider changes to transmission intensity or a shift from an epidemic to endemic pattern of disease . the increase in number of people at risk and
hence the potential infections observed over the next four decades is gradual and due solely to expected population growth in existing dengue regions rather than to a geographic expansion of transmission - suitable areas . around mid - century , however , step - changes occur under each of the three no action scenarios as a result of geographic expansion incorporating new population centres . by the end of the century , strong mitigation action could reduce the number of people living in dengue transmission zones in australia by between 80 and 90% , depending on how regional climates respond to increased carbon concentrations ( becoming dryer or wetter , respectively ) . the regional contributions to australia 's blood supply , estimated by current self - report of
regular donation and the percentage of australia 's population in each state and territory is shown in table 3 .
the estimated future proportion of the state 's population living in transmission - risk areas in selected years is shown in table 4 .
australia 's blood donors by state / territory and population distribution proportion of the population within each dengue - risk state living in transmission areas under the four scenarios note : this proportion is extrapolated from the current pattern of residence and no allowances have been made for future contributions from internal migration .
as reduction in blood supply during an outbreak is geographically determined , the proportion of the population in each state living in transmission - risk zones relates directly to the potential decline in blood supply in each state during an outbreak ( assuming that blood donors are evenly distributed throughout the population of each state ) .
we estimated the percentage of donors in each state that are likely to be at least periodically affected by dengue outbreaks by multiplying the proportion of each state 's population in transmission - risk zones by each state 's percentage contribution to national blood supply ( table 5 ) .
projected decline in blood supply in australian states and territories with high risk transmission regions , and nationally blood supply in the state of queensland will be most affected as it can expect declines of at least between 61 and 93% of its blood supply by the end of the century ( and at least 15% in the decades before then ) , which will occur at least periodically if transmission patterns do not intensify .
estimates of the average annual economic costs to public health and surveillance are shown in table 6 and estimated annual number of work days lost are shown in table 7 .
average annual public health costs ( millions $ aus ) under the four scenarios for selected years , based on cost per person living in regions at risk average annual number of lost workdays under the four scenarios , based on days per person living in regions at risk
under each of the three no emissions action scenarios , there is an increase in the geographic spread and hence the number of sds that are favourable to dengue transmission ( fig .
, the geographic region suitable for the transmission of dengue is expected to extend far to the south and west from its current distribution .
the regions at risk include all coastal areas of queensland and into new south wales , northern western australia and the northern territory . in scenarios 1 ( hot and dry ) and 2 ( hot , median humidity ) , dengue transmission areas extend south in queensland to include brisbane ( and west to mt isa in scenario 2 ) , and into broome in western australia .
in contrast , under emissions mitigation ( the strong action scenario 4 ( warm ) ) , dengue transmission - suitable areas remain limited to northern queensland and to darwin .
areas suitable in australia for dengue transmission in 2100 under four climate change scenarios ( > 50% likelihood of transmission ) .
the number of people at risk from dengue ( i.e. the population living in transmission - risk areas ) estimated under each scenario in coming decades is shown in fig . 3 , and the percentage changes are represented in table 1 . the number of people living in regions in australia at high risk ( > 50% ) of dengue transmission under four climate change scenarios .
scenarios : 1 , hot ( dry ) ; 2 , hot ( median humidity ) ; 3 , hot ( wet ) ; 4 , warm ( strong mitigation ) .
percentage change in numbers of people living in transmission - risk areas , selected years annual rates of confirmed infection are estimated to be between 47/100,000 and 230/100,000 in dengue susceptible regions , with a further 28/100,000138/100,000 sub - clinical infections likely .
table 2 shows the range estimate for the number of people to be infected with dengue based on the exposed population and these current rates of infection .
estimated annual numbers of new dengue infections under the four climate scenarios
using population at risk projections ( fig .
3 ) . lower estimate is calculated from average annual incidence rate 19912007 ; upper estimate is calculated from the much larger 20082009 outbreak .
these upper estimates are likely to be conservative in a climate changed future as they do not consider changes to transmission intensity or a shift from an epidemic to endemic pattern of disease .
the increase in number of people at risk and hence the potential infections observed over the next four decades is gradual and due solely to expected population growth in existing dengue regions rather than to a geographic expansion of transmission - suitable areas . around mid - century , however , step - changes occur under each of the three no action scenarios as a result of geographic expansion incorporating new population centres . by the end of the century
, strong mitigation action could reduce the number of people living in dengue transmission zones in australia by between 80 and 90% , depending on how regional climates respond to increased carbon concentrations ( becoming dryer or wetter , respectively ) .
the regional contributions to australia 's blood supply , estimated by current self - report of regular donation and the percentage of australia 's population in each state and territory is shown in table 3 .
the estimated future proportion of the state 's population living in transmission - risk areas in selected years is shown in table 4 .
australia 's blood donors by state / territory and population distribution proportion of the population within each dengue - risk state living in transmission areas under the four scenarios note : this proportion is extrapolated from the current pattern of residence and no allowances have been made for future contributions from internal migration .
as reduction in blood supply during an outbreak is geographically determined , the proportion of the population in each state living in transmission - risk zones relates directly to the potential decline in blood supply in each state during an outbreak ( assuming that blood donors are evenly distributed throughout the population of each state ) .
we estimated the percentage of donors in each state that are likely to be at least periodically affected by dengue outbreaks by multiplying the proportion of each state 's population in transmission - risk zones by each state 's percentage contribution to national blood supply ( table 5 ) .
projected decline in blood supply in australian states and territories with high risk transmission regions , and nationally blood supply in the state of queensland will be most affected as it can expect declines of at least between 61 and 93% of its blood supply by the end of the century ( and at least 15% in the decades before then ) , which will occur at least periodically if transmission patterns do not intensify .
estimates of the average annual economic costs to public health and surveillance are shown in table 6 and estimated annual number of work days lost are shown in table 7 .
average annual public health costs ( millions $ aus ) under the four scenarios for selected years , based on cost per person living in regions at risk average annual number of lost workdays under the four scenarios , based on days per person living in regions at risk
in coming decades in australia , the geographic regions favouring dengue transmission are expected to expand across a number of states and encompass new populations unless strong mitigation action is taken .
if no or insignificant action is taken to reduce global carbon emissions , the distribution of dengue transmission - suitable areas could , at the very least , progress southward along the queensland coast and include the northernmost parts of western australia .
if conditions are wetter , transmission - suitable areas could extend into new south wales along the east coast , as far south as port hedland in western australia and throughout the northern territory . in terms of numbers of people affected , up to eight times as many people could be at risk compared to scenarios based on strong mitigation .
if several dengue outbreaks were to occur spontaneously in different areas or spread between the newly transmission - suitable regions , blood collections and potentially the supply of fresh blood products could be greatly reduced across australia .
people living in towns and cities never before exposed to dengue would be especially susceptible during outbreaks . large numbers of people could become infected , increasing the amount of virus circulating in the population and furthering risk of transmission .
for example , in 1993 , an estimated 26% of the population were infected in one outbreak that occurred in the queensland town of charters towers ( 22 ) .
it predicts current global dengue presence with an accuracy of 89% based on areas deemed to have a greater than 50% chance of transmission ( 12 ) .
this means that some regions returning a lower than 50% probability estimate in the model could still be suitable for dengue transmission , and dengue will , on occasion , occur outside these areas .
such is the case with townsville which was affected by the most recent australian outbreak .
importantly , this model does not predict vector distribution but rather regions suitable for future virus transmission , based on current known transmission regions .
vectors do exist , and have existed in the past , in regions in australia where transmission does not currently occur ( 23 ) .
the model is thus influenced by human behaviour , such as surveillance programmes that have kept dengue from being more widespread in recent years than it otherwise might be , and is informed by current urban features and infrastructure .
for example , near universal water reticulation in non - remote areas of australia has reduced domestic storage and thus a. aegypti breeding sites .
such behavioural factors and infrastructure are not static ; beebe et al . have suggested that human adaptation to climate change may cause further spreading of the aedes mosquito in australia and more intense epidemics as recent prolonged water shortages have already , in some urban areas , led to the re - installation of domestic water storage facilities ( 23 ) .
the altered distribution of dengue modelled here is predicted to reduce queensland 's blood supply by between 61 and 93% by the end of the century , unless strong mitigation action is taken .
although changing transmission intensity was not modelled here , it is a likely outcome of climate change , especially in regions that become more humid or where minimum temperatures ( night - time or winter - time ) are not sufficiently low to disrupt either vector activity or replication of the virus ( 24 ) .
again conservatively , we estimate that blood supply in the northern territory could be reduced by more than double the current potential periodic loss , and australia 's national supply could be reduced by up to 20% .
larger reductions in queensland 's blood supply are likely to occur earlier than modelled here as some years will most certainly experience outbreaks outside these boundaries . under all but the strong mitigation scenario ,
the potential economic costs of dengue to australia are considerable ; up to $ 22 million annual public health costs in today 's terms , and 40,000 work days if transmission intensity remains unchanged .
the costs of other vector - borne disease not modelled here are also likely to be affected by climate change in a similar manner .
we used costs from 2006 to 2008 and did not account for any variation in costs over time .
we assumed , conservatively , that the cost per person will remain the same in future , and that the pattern of dengue in australia will also remain the same ( i.e. epidemic ) . if , however , changing transmission patterns mean that dengue becomes established in australia , the associated health system costs are likely to increase substantially above our estimated baseline per person amount .
first , unlike the present , there would no longer be years with few or even no cases of dengue recorded .
second , a much larger campaign of mosquito eradication would be needed across the endemic towns and cities .
this would involve trained personnel , broad scale and intensive community education , and mosquito spraying .
currently this work is only focused on hot spots the local areas ( usually sections or suburbs ) where cases have been identified in a particular season .
we made no assumptions about future tourism patterns and how these may affect the introduction of dengue cases . at present , all outbreaks in australia begin with an infected person who enters from another country . if tourism were to increase markedly ( especially to and from dengue - endemic countries ) , this might result in more outbreaks in australia .
as well , the introduction of other serotypes of dengue ( and hence the risk of the more serious complication of dengue haemorrhagic disease ) will also come from residents returning or foreign tourists .
this is a random event , and we have not modelled the possible consequences and costs involved .
factors that affect disease severity include ethnicity , age , nutritional status , the sequence of two different dengue infections , the genotype of the infecting virus , and the competence of the clinical and laboratory surveillance systems .
we assumed that australia 's future health system , demographic , social and environmental influences on disease severity will broadly represent those of today . currently , there are very few deaths due to dengue fever in australia ( about 0.3 deaths per year ) .
the number of deaths from exposure to different dengue serotypes is , however , likely to increase if dengue transmission becomes more intense and the virus becomes endemic as the risk of sustaining multiple infections in a lifetime increases .
we have assumed that the average number of dengue haemorrhagic fever cases is not likely to increase in future .
australian cases that occurred between 2003 and 2004 were aged 3270 years , but in southeast asia , dengue haemorrhagic fever predominantly occurs among children .
a possible explanation for the older age of patients in northern queensland is the long period between the dengue 1 and 2 epidemics in this region , which means that only older people or those who had been infected previously while overseas were susceptible to dengue haemorrhagic fever .
if outbreaks of different dengue serotypes occur more frequently in future ( due to random chance , increased global virus activity or higher tourism numbers ) , or if dengue became established locally , this would probably change the age profile of haemorrhagic fever towards younger people ( 24 ) .
worldwide , the warmer temperatures associated with climate change are expected to enhance transmission in already affected areas and to increase the likelihood of its emergence in new areas ( 25 ) .
scenario - based modelling using global climate models and average temperature increases has consistently projected increases to the latitudinal range of dengue transmission and increased transmission intensity in already affected areas , and predicts that the dengue virus will become established in areas that are currently marginal for transmission .
for example , over the coming decades dengue is predicted to spread into new areas further south in south america and africa as well as australia ( 12 , 24 ) , further north into the usa ( 12 ) , while parts of india , the middle east and southeast asia classified as low risk will become high risk ( 12 ) .
these models found that transmission intensity is expected to increase not only in northern australia , but also across india and thailand , eastern and northern africa , and in south and central america .
the epidemic potential of dengue virus is expected to increase in a number of major cities even with only a small increase in average temperature ( 26 , 27 ) , and new patterns of year round transmission occurring in some regions , including northern australia ( 24 ) .
the modelling of dengue and blood supply in australia thus highlights what is most certainly a global problem ; climate change induced blood shortages and impacts on safety could become a significant and long - term issue , especially in regions already struggling to control vector - borne disease or those that are presently on the margins of current disease distribution , and even more so in countries which already struggle to meet their blood supply needs .
such changes are probably already well underway ; the incidence of dengue is observed to be increasing in parts of the americas and asia ( 28 , 29 ) .
the potential for climate change to reduce future blood supply extends to a number of other vector - borne pathogens .
the transfusion - transmissibility of other vector - borne viruses of importance to australia , including ross river virus , barmah forest virus and murray valley encephalitis is currently unknown ( 30 ) .
these viruses are also expected to increase in incidence , intensity and geographic distribution as conditions become more favourable to mosquitoes and virus replication , a situation that could have further detrimental impacts on australian blood supply .
climate change impacts could further contribute to future blood shortages across the world as other globally important vector - borne diseases are similarly affected . while the modelling presented here
examines average trends across coming decades for a single virus , there is considerable evidence that transmission of a number of vector - borne diseases is already intensifying and expanding geographically .
for example , the recent emergence of chikungunya in northern italy caused a reduction in blood supply and plasma for manufacture ( 31 ) , while this and other vector - borne diseases such as west nile virus are becoming established in previously unaffected regions ( 32 , 33 ) .
the increasing global movement of blood and blood products adds another dimension to future blood safety ; transfusion transmission risk is not geographically contained in an already affected region and could potentially lead to local transmission in a previously unaffected area , while any contaminated supplies are becoming more difficult to trace and recall . in the modelling of future reductions in blood supply , a possible change to the use of blood products was not taken into account
. the annual rate of ivig use in australia has increased approximately 57% since 2003 and platelet use has increased approximately 13% , while plasma - derived factor viii and factor ix have declined in favour of recombinant technology over the same period ( 34 ) .
it is not possible to speculate reasonably on whether the net therapeutic need for blood will increase or decrease in coming decades . by mid - century , rather than merely increasing the frequency or amplitude of outbreaks in already affected areas as seems to be occurring
, the impact of climate change on expanding dengue - transmission regions in australia will become obvious . by then , it is possible that medical therapies will no longer rely on donated blood , or that dengue has become a readily treatable or curable infection , or that an accurate and reliable screening test has become available .
the development of an effective dengue vaccine and/or the future application of pathogen reduction technology to blood components may also mitigate the risks .
however , there remain a large number of other vector - borne pathogens , and possibly some emerging ones , that will also be affected by climate change .
if the current situation for screening and vaccination , and our reliance on blood products holds for the future , we expect the safety and availability of blood products around the world to be compromised by climate change unless blood collections can be adequately increased in non - affected areas .
other countries already intensely affected by dengue may experience much earlier increases in the transmission range and intensity of vector - borne disease than is expected for australia , and will be thus be subject to contemporary medical technology and therapy . with its national control of blood component inventory ,
australia is well prepared to be able to move blood components into areas of need as required ( anthony keller , personal communication ) .
many other regions of the world do not have such a safety net that can be invoked when outbreaks occur , and with climate change expected to affect a number of vector - borne infections worldwide , periodic or even continuous shortfalls in blood supply should be expected and planned for .
climate in australia and elsewhere over coming decades will be shaped by future global carbon emissions .
the level of global emissions will be heavily dependent on the action taken by national governments , especially those of currently high polluting countries , such as australia , and those with large populations that are rapidly industrialising , such as india and china . while some climate change is already in the pipeline , strong emission reductions are needed to avert global average warming of greater than 2c , the threshold of dangerous and irreversible climate change ( 35 ) .
it is estimated that a 50% global reduction in emissions by 2050 is required in order to stabilise co2 concentration below 450 ppm and warming below 2c ( 35 ) , equivalent to the strong mitigation scenario that was used here .
international action on emissions at this level could help safeguard future blood supply around the world , as demonstrated here for dengue transmission in australia .
however , both the virus and the vectors are highly sensitive to climate , thus even a much smaller increase in global mean temperature will affect and may already be affecting the transmission of vector - borne disease . importantly , and perhaps as demonstrated by the recent epidemic of dengue in australia , outbreaks of vector - borne disease will become more difficult to control as the climate changes .
regions that are currently under disease surveillance may need to expand rapidly and control measures implemented swiftly .
regulatory action to reduce potential breeding habitats should be considered well in advance , such as adequate screening of water tanks to inhibit oviposition by mosquitoes , even if global warming is kept to a minimum by strong emission reductions .
it is difficult when assessing the impacts of climate change on any health outcome to predict precise changes in occurrence or distribution .
this is especially true for vector - borne diseases , where innumerable environmental , human and other animal behaviours and physiologies are affected ( 36 ) .
the example presented here of how climate change could affect the supply of blood in australia by extending the range of dengue - favourable environments illustrates what should be a global concern , and highlights the importance of considering what may be a less obvious climate impact on health .
this work was partially funded by the australian federal government 's garnaut climate change review and the school of medicine , university of western sydney internal grant scheme . | backgroundclimate change is expected to promote more intense and prolonged outbreaks of vector - borne disease , and alter the geographic boundaries of transmission .
this has implications for the safety and supply of fresh blood products around the world . in australia ,
a recent outbreak of dengue fever caused a prolonged regional shortage in the supply of fresh blood products.objectiveto highlight the potential for climate change to affect the safety and supply of blood globally through its impact on vector - borne disease , using the example of dengue in australia as a case-study.designwe modelled geographic regions in australia suitable for dengue transmission over the coming century under four climate change scenarios , estimated changes to the population at risk and effect on blood supply.resultsgeographic regions with climates that are favourable to dengue transmission could expand to include large population centres in a number of currently dengue - free regions in australia and reduce blood supply across several states.conclusionunless there is strong intergovernmental action on greenhouse gas reduction , there could be an eight - fold increase in the number of people living in dengue prone regions in australia by the end of the century .
similar impacts will be experienced elsewhere and for other vector - borne diseases , with regions currently on the margins of transmission zones most affected .
globally , climate change is likely to compound existing problems of blood safety and supply in already endemic areas and cause future shortages in fresh blood products through its impact on transmission of vector - borne disease . |
@xcite conducted a comparison project of numerical simulations of the formation of a massive cluster of galaxies in a cold dark matter ( cdm ) universe in which the results of twelve independent simulation codes were compared . both eulerian mesh codes and lagrangian smoothed particle hydrodynamics ( hereafter sph ; * ? ? ?
* ; * ? ? ?
* ) codes were used in this comparison project . in this project
, they took into account only gravity and hydrodynamics so that the comparison was simplified .
this project is known as the `` santa barbara cluster comparison project '' .
although most of global properties reasonably converged , there was a systematic difference in entropy profiles of the clusters in simulations with different methods .
the results of the eulerian mesh codes showed the central core in entropy profiles , whereas those of sph codes did not ( see figure 18 in their paper ) .
later studies confirmed this tendency ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
@xcite interpreted that this difference might reflect the difference in the treatment of shocks of sph and mesh codes .
@xcite pointed out that there are `` fundamental differences '' between eulerian mesh and lagrangian sph codes ( see also * ? ? ?
* ; * ? ? ?
this difference is originated from the fact that the standard formulation of sph ( hereafter ssph , where @xmath0 and @xmath1 are the mass and density of a particle , as the discrete volume element for the discretization of the equations . ] ) has difficulties when dealing with contact discontinuities .
since ssph requires the differentiability of the density field , the density around a contact discontinuity has a large error .
in particular , the density of particles in the low - density side of the contact discontinuity is overestimated by a large factor .
this error propagates to the pressure evaluation , resulting in the _ unphysical surface tension _ and the suppression of fluid instabilities ( see figure 1 in * ? ? ?
we can solve this problem by using the volume element which does not depend on the density @xcite , by introducing extra dissipation terms @xcite , by using the integration form to evaluate the derivatives of physical quantities @xcite , by employing the non - standard equation of motion which breaks newton s third law @xcite , and by adopting the godunov sph @xcite where physical quantities are smoothed twice @xcite .
@xcite used a diffusive quantity , @xmath2 , instead of the mass and mass density , to formulate the sph approximation .
each particle has the @xmath3 , and from that its density is calculated using the usual formula to calculate mass density from mass of particles in sph .
since all of the sph codes used in the santa barbara cluster comparison project were based on ssph , the cuspy entropy profile obtained with sph codes might be , at least partly , the artifact caused by the unphysical surface tension . in the hierarchical structure formation scenario , a cluster of galaxies grows through mergers of a number of small building blocks which contain cold , low - entropy gas .
the unphysical surface tension of ssph tends to protect cold gas clumps in the building blocks against the fluid instabilities and the ram - pressure stripping , as demonstrated by the `` blob test '' of @xcite . as a result
, cold clumps might reach the center of the cluster due to the dynamical friction with keeping their low entropy state , resulting in a cuspy entropy profile of the cluster .
some of techniques described above have been applied to the cluster formation simulations in order to investigate their effect on the central entropy structure .
@xcite added a diffusion term to the energy equation which mimics the turbulence mixing and performed the santa barbara cluster simulations .
they found that the entropy core could be formed , but the size and depth of the entropy core depended strongly on the diffusion coefficient and numerical resolutions ( see their figures 12 and 13 ) .
@xcite carried out a set of comparison tests of the cluster formation in a @xmath4cdm universe with sph and an adaptive mesh refinement ( amr ) codes , focusing on the formation of the entropy core . in their comparison tests , they used not only ssph but also their new sph , sphs @xcite which avoids multivalues of physical quantities by artificial diffusion terms with a higher order dissipation switch and increases the force accuracy by adopting a higher order kernel with a large number of neighbor particles . in sphs runs ,
the entropy core was formed in the cluster center and its size was consistent to that obtained by an amr code , ramses @xcite .
this good agreement is achieved when the maximum dissipation parameter @xmath5 ( see their figure 6 ) . on the other hand , in the case with @xmath6 ,
the entropy profile has a core , but it is smaller and the core entropy is lower than those with converged values . in the case with @xmath7 , it is close to that found with ssph .
recently , @xcite reported a new comparison test of a numerical cluster in a @xmath4cdm universe .
they showed that sph codes with the artificial conductivity ( hereafter ac ) term and sphs give entropy profiles which are close to those given by amrs ( i.e. , cored profiles ) , although they did not provide the results of the parameter tests .
the agreement with the results of amr calculations does not guarantee the validity of the results , since eulerian schemes have their own limitations .
an obvious one comes from its eulerian nature . in order to integrate the motion and internal energy of fast - moving cold gas clump
, very high accuracy is required .
the internal energy of a gas clump can be many orders of magnitudes smaller than its kinetic energy in the reference frame of the mesh .
numerical error comes from the kinetic energy , but it affects the internal energy of the clump .
consider the case that a molecular cloud moves in a galaxy following the galactic potential .
the typical temperature of the cloud is @xmath8 while the virial temperature which corresponds to the typical kinematic energy is @xmath9 for a galaxy of the milky way size .
the energy difference between the thermal and kinetic energies of the cloud becomes about five orders of magnitude .
very high accuracy is , thus , required to keep the structure of the clump , and this requirement in turn results in the requirement of high spacial resolution and small time step .
otherwise , a large error is induced by the loss of significant digits and/or negative pressure .
a remedy for this problem is the dual energy formulation @xcite . in this formulation , both total ( @xmath10 ) and internal ( @xmath11 ) energies are solved independently .
then , either @xmath11 or @xmath12 , where @xmath13 is the kinetic energy , is used to evaluate pressure , depending on the fraction of the thermal energy . for the high mach number fluid , e.g. , @xmath14
, @xmath11 is adopted to evaluate pressure . otherwise , since @xmath15 , the loss of significant digits occurs .
another difficulty is that the eulerian formulation is not the galilean invariant , which leads to the numerical diffusion .
an example of this problem can be seen in figure 14 of @xcite . in eulerian codes ,
an initially hydrostatic cluster decays after 1 gyr evolution , in particular in enzo @xcite with zeus @xcite and flash @xcite , when a translational velocity was added . in principle , by going to higher spatial resolution , we can reduce the rate of decay by reducing the effect of the numerical dissipation @xcite .
nevertheless , compared to lagrangian codes with the same effective accuracy , the computational cost would be much higher .
the other way is to adopt higher spatial order schemes , such as essentially non - oscillatory polynomial interpolation ( eno ; * ? ? ?
* ) , weighted eno ( weno ; * ? ? ?
* ) , and constrained interpolation profile ( cip ; * ? ? ?
* ) schemes
. however , these schemes are computationally expensive and it is difficult to combine high - order schemes with amr in a consistent way .
the latter is serious because joint interfaces of finer and coarse meshes lose their accurracy @xcite and thus careful treatment is necessary .
recently , novel numerical schemes have been developed and used in the field of numerical astrophysics .
@xcite developed a moving mesh scheme which is free from the above problem of the eulerian mesh codes . in @xcite
, he carried out simulations of the santa barbara cluster with `` arepo '' , an implementation of his moving mesh scheme , and reported that the entropy core was formed .
the size of the core is smaller than those obtained by amr simulations and the entropy at the core is lower than those obtained by amr simulations .
@xcite developed a new code `` gizmo '' which implemented a meshless method and found that in cluster simulations with gizmo entropy cores similar to those of arepo is formed .
these results are quite encouraging
. however these two codes use similar approaches , such as quasi - lagrangian nature using riemann solvers .
further tests with different schemes are important . in this paper
, we report the results of santa barbara cluster simulations obtained with the density independent formulation of sph ( disph ) @xcite .
since disph is free from the unphysical surface tension , we can expect that it gives better results compared to ssph .
in addition , since disph do not introduce artificial dissipations , we can expect that the result is not affected by free parameters .
the structure of this paper is as follows . in [
sec : disph ] we give a brief review of the formulation of ssph and disph and their advantages and disadvantages .
we then describe the initial condition and our numerical methods in [ sec : method ] .
the comparison is carried out in [ sec : results ] and discussion is given in
[ sec : discussion ] .
in the sph method , all physical quantities are evaluated using the kernel approximation over the field discretized by particles .
the kernel approximation for a physical quantity @xmath16 is given by @xmath17 where @xmath18 and @xmath19 are position vectors , @xmath20 is a function with a compact support called the kernel function , and @xmath21 is the kernel size .
we approximate this spatial integration by the summation over particles expressed as @xmath22 where @xmath23 and @xmath24 are the values of @xmath16 at the positions of particles @xmath25 and @xmath26 , respectively , and @xmath27 is the volume element associated with particle @xmath26 . in ssph , we use @xmath28 where @xmath29 and @xmath30 are the mass and density of particle @xmath26 , respectively . from eqs . and , by substituting @xmath1 into @xmath16
, we have @xmath31 note that eq .
gives the _ smoothed _ estimate of the density field .
thus , the density near a contact discontinuity suffers a very large error .
consider the case that we evaluate the density around a contact discontinuity using eq .
the density of a particle at the low - density side is over - estimated , while that of a particle at the high - density side is under - estimated .
the absolute amount of the error is similar at the both sides .
the relative error is much larger at the low - density side , simply because the true density is smaller .
this large overestimate of the density results in equally large overestimate of the pressure for low - density particles near the contact discontinuity , which then causes a strong repulsive force .
this repulsive force works as an unphysical surface tension ( e.g. , * ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
if the distribution of the internal energy is sufficiently smooth , this unphysical surface tension does not show up even with the smoothed density . the ac term introduced by @xcite automatically reduces the pressure jump by spreading the internal energy . .
] a switch is always used to avoid unnecessary diffusion . in disph , unlike ssph , the pressure ( or its arbitrary function ) is used to evaluate the volume element @xcite .
the pressure field is smooth everywhere , except at the shock front . in sph ,
the shock is handled by the artificial viscosity ( hereafter av ) which smooths the velocity field and prevents multivalues . as a by - product , we have a smoothed pressure distribution in sph simulations , even at the shock front .
therefore , we can expect that the problem of ssph at the contact discontinuity is solved if we use a volume element based on the pressure .
this is the basic idea of disph .
the simplest form of the fundamental equation used in disph can be obtained by using the volume element @xmath32 , where @xmath33 and @xmath34 are the energy density and the internal energy of particle @xmath26 , respectively .
substituting @xmath35 into @xmath16 in eq . and using the energy density based volume element , we have @xmath36 since the pressure is smooth at contact discontinuities and even at the shock front , we can obtain smoothed values without large errors .
note that , if one uses disph for a non - ideal gas , one needs to use pressure directly instead of the energy density @xcite , because it is no longer smooth .
we note that this formulation itself does not introduce any dissipation .
in disph , as a trade - off for using of the smoothed pressure for the formulation , the density distribution has a jump at a contact discontinuity if the internal energy distribution there is not smooth ( see figure 2 in * ? ? ?
* ) . while this jump does not affect the motion of particles , it is necessary to be aware of this `` unphysical '' density jump when one uses this density to evaluate physical quantities , such as radiative cooling
as is noted by @xcite and @xcite , the simplest solution is to use the smoothed density . in the same manner as ssph , disph can conserve the total energy , linear and angular momentum .
if we use a variation principle for the derivation of sph equations @xcite , we can obtain a set of conservative sph equations @xcite .
the equations in this derivation have the so - called `` grad-@xmath21 '' term . moreover ,
if we carefully constructs energy and momentum equations , we can obtain another set of the conservative equations which do not involve the grad-@xmath21 term ( see section 5.6 in * ? ? ?
here we adopt disph with the grad-@xmath21 term , which is more robust under the strong shock . in appendix
[ sec : method : timeintegration ] , we show the result of the three - dimensional collapse test @xcite .
the relative energy error from the beginning and the end of the simulation is @xmath37% , which is comparable to the previous studies ( e.g. , * ? ? ?
* ; * ? ? ?
the initial condition we used here is basically the same as that used in @xcite .
the volume of their initial condition is @xmath38 in the comoving space and the initial redshift is @xmath39 .
the @xmath40 overdensity is imposed at the center of the volume so that a massive cluster will be formed at the center .
there are two set of initial conditions with different resolutions : @xmath41 and @xmath42 particles .
the cosmology is the standard cdm and the hubble parameter is @xmath43 where @xmath44 .
we integrated the formation and evolution of the santa barbara cluster with a vacuum boundary condition in the physical space .
we cut the central spherical volume with the radius of @xmath45 in the comoving space and remapped it to the physical space at @xmath46 .
then , we imposed the hubble flow corresponding to the initial redshift .
following @xcite , we assumed @xmath47 and @xmath48 .
since the original initial conditions of @xcite are for dm only simulations , we divided each particle into two particles which have the same position and velocity of the original particle but have different masses , i.e. , that one has @xmath49 and the other has @xmath50 of the original particle mass , for simulations involving both dm and gas . the number of particles , the mass of particles and the spatial resolutions ( softening lengths for dm and baryon : @xmath51 and @xmath52 ) are summarized in table [ tab : parameters ] .
for both of low- and high - resolution models , we performed two runs , one with the standard sph , and the other with disph .
we carried out five high - resolution ssph runs involving ac .
these five runs adopted different values for the maximum dissipation parameter .
in addition , two extra models which combine the low mass and the high spatial resolutions ( mixed 1 ) and the high mass and the low spatial resolutions ( mixed 2 ) are adopted in order to investigate the effect of the resolutions further .
we also carried out two runs with ssph and disph for each model .
thus , in total we performed thirteen runs . [ cols=">,^,^,^,^,^",options="header " , ] + we used a parallel @xmath53-body / sph code asura @xcite for this experiment .
the gravitational interactions between particles were calculated by the tree method @xcite . the tree with grape method @xcite was used .
the parallelization method of the gravity calculation was that proposed by @xcite .
we adopted the symmetrized plummer potential and its multipole expansion @xcite so that we can calculate the gravitational interactions between particles with different values of softening lengths by a single tree .
the opening angles for the ordinary three dimensions and softening lengths were set to @xmath54 following @xcite .
the phantom - grape library was used for the calculation of particle - particle interactions in order to accelerate the calculation @xcite .
the equation of state of the ideal gas with the specific heat ratio @xmath55 was used . in order to handle shocks ,
the av term proposed by @xcite was used .
in addition to this , we used an av switch proposed by @xcite in which the value of the av parameter , @xmath56 , changes in the range of @xmath57 . following @xcite , a modification which accelerates the increase of @xmath56 at lower @xmath56 regime and slows it at higher @xmath56 regime
was also used .
the balsara limiter @xcite was adopted in order to reduce the shear viscosity .
we employed the wendland c4 kernel which is free from the paring instability @xcite .
the number of neighbor particles was kept within @xmath58 .
this higher order kernel with a larger number of neighbor particles can reduce the so - called e0 error @xcite .
the time integration was carried out by a second order scheme ( see appendix [ sec : method : timeintegration ] for details ) .
the individual and hierarchical time - step methods were used @xcite . for sph particles , the time - step limiter , which enforces the time - step difference among neighboring particles to be small enough to follow strong shocks ,
was used @xcite .
the fast scheme , which allows each particle to have different time - steps for gravitational and hydrodynamical interactions and integrates these two interactions independently , was also adopted @xcite .
when we used the fast scheme , the computational time ( wall - clock time ) became half of what it was without fast ( we used 128 cpu cores of cray xc30 in this comparison ) .
this gain is almost the same as that reported in @xcite , although simulation setups in both runs were completely different .
following previous studies @xcite , we define a dense region which is formed at the center of the simulation volume and with the mean density is 200 times higher than the background density as the `` santa barbara cluster '' .
we express the radius where the mean density becomes 200 times of the background density as @xmath59 and call it the virial radius .
the procedure to find the center and size of the santa barbara cluster is as follows .
first , we find a particle of which total energy is the lowest and adopt it as the center of the cluster of galaxies .
then , we sort all of particles based on the distance from the center of the cluster in ascending order .
we calculate the mean density from the center to the outer part following the particle order , and we halt this operation when the mean density becomes less than 200 times of the background density .
we regard the distance from the center to the particle position where we halt this operation as the virial radius .
this simple strategy works well for the santa barbara test in which a single massive cluster is formed near the center of the simulation volume . in order to draw radial profiles
, we use a density weighted center instead of the halo center since the peak of the baryon distribution does not always coincide with the position of particle with the lowest total energy .
we use the following definition as the density weighted center @xcite : @xmath60 where we only take care of the gas particles in the virial radius . for this density @xmath30
, we just used the ssph - estimated density .
the kernel function and the number of neighbor particles are the same as those described in [ sec : method : numerical ] .
in this section , we compare the properties of the santa barbara cluster obtained by simulations with ssph and disph , and then investigate the origin of the difference in the entropy profile .
we first describe the global properties of the santa barbara cluster in [ sec : results : globalproperties ] .
the density , temperature and entropy distributions in the clusters obtained by simulations with ssph and disph at @xmath61 are compared in [ sec : results : snapshots ] . in [ sec : results : radialprofile ] , we compare radial profiles .
we investigate how the central entropy core / cusp formed in [ sec : results : entropy : formation ] . in
[ sec : results : ac ] , we investigate the contribution of the ac term for the cluster entropy profile . in order to avoid confusion
, we use the label `` sph '' to indicate the results of ssph on figures and `` disph '' for the results of disph .
the average of virial radii of the santa barbara clusters of the four runs ( the high- and low - resolution runs with ssph and disph ) is @xmath62 .
this radius is somewhat larger than those obtained in previous studies @xcite .
the total mass within @xmath59 is @xmath63 which is @xmath64 larger than those obtained by @xcite .
these differences are probably due to the difference in the treatment of the boundary condition .
we used the open boundary condition , while all runs in @xcite adopted the periodic boundary condition .
since the radius of the initially imposed overdensity region is @xmath65 , the cut - off radius of @xmath45 would be insufficient to remove boundary effects . nonetheless , as we see later , the central region of the cluster does not seem to be affected by the boundary condition . in the following , we call the santa barbara cluster just `` cluster '' , for brevity .
we found that the clusters obtained by disph contain more gas than those obtained by ssph .
the gas fractions of the cluster with disph are @xmath66 which are close to the results of high resolution mesh codes in @xcite and also the cosmic averaged value of @xmath67 for this model . on the other hand , those of ssph are
@xmath68 which are close to those of ssph runs in @xcite , @xmath69 .
figure [ fig : virial : density ] shows the gas density maps of the four runs within @xmath59 at @xmath61 .
these density maps are not very different . however ,
when we inspect these maps carefully , we find several differences .
first , we can see that the central densities in runs with ssph are higher than those with disph .
the density of the innermost regions of the clusters with ssph is one order of magnitude higher than that with disph .
second , for both of ssph and disph runs , the central density of the cluster is higher for runs with high mass resolution ( large number of particles ) .
figure [ fig : virial : temperature ] shows the temperature distribution within the cluster of four runs .
we can see that the clusters of ssph runs contain more small - scale substructures compared to those of disph runs .
figure [ fig : virial : entropy ] shows the entropy distributions ; the definition of the entropy we adopted in this paper is @xmath70 where @xmath71 and @xmath1 are the temperature in the unit of kelvin and the density in the unit of @xmath72 , respectively , and this definition is the same as that used in @xcite .
it is obvious that the values of the central entropy in ssph runs are much lower than those in disph runs .
the clusters in disph runs have no or a little amount of gas with entropy below @xmath73 , while the clusters in ssph runs have significant amounts of such gas at the center .
it is also clear that the entropy distributions of the cluster in disph runs are smoother than those of clusters in ssph runs . in other words
, the entropy distribution indicates that the gas in the clusters of ssph runs is not well mixed .
figure [ fig : radialprofiles ] shows the radial profiles of the cluster at @xmath61 . in this figure , we used two high - resolution results . in this plots ,
`` sb '' denotes the averaged profiles in @xcite , `` arepo '' is the result of a moving mesh code arepo by @xcite . as expected , with this formalism the entropy generation is slightly suppressed @xcite . on the other hand
, @xcite pointed out that spurious heating from riemann solver errors affects an entropy profile when this formalism turned off .
hence , we adopt the original data shown in @xcite .
] , and `` nyx '' denotes the result of an amr code nyx by @xcite .
-body / gas dynamics code designed for large scale cosmological simulations . in this code , the fluid evolution is solved by a finite volume method with a block structured amr .
the dual energy formulation is used .
the riemann solver is used for the evaluation of fluxes . according to these features ,
nyx is one of good representatives of the state - of - the - art amr codes .
the entropy profile of the santa barbara cluster with nyx is almost identical to those with enzo @xcite and art @xcite . ]
we note that these data were taken from figures in their papers : figure 18 in @xcite for sb , figure 45 in @xcite for arepo ( we adopt the result labeled @xmath41 ) , and figure 7 in @xcite for nyx .
we also note that the entropy profile with gizmo reported by @xcite is comparable to that with arepo .
the density profiles of dm ( the top - left panel of figure [ fig : radialprofiles ] ) of all four runs agree very well .
the central density of gas of the ssph run is significantly higher than those of the other three runs . here , `` sb '' , `` arepo '' and our disph results seem to agree well .
note , however , that the `` sb '' plot is the average of 7 sph and 5 mesh - based scheme runs , and sph models in @xcite gave the result similar to our ssph run , while the mesh runs gave a central density even lower than arepo / disph results .
thus , the agreement between our disph result and the arepo result is rather good , whereas all ssph runs gave high central densities and amr runs , lower density . from the temperature profile ( the left - bottom panel of figure [ fig : radialprofiles ] ) and density profile ( the top - right panel ) of the gas component , we can see that the standard sph gives a central cusp with the temperature decreasing inward , while arepo and disph give constant - density , constant - temperature cores .
mesh runs in @xcite also gave constant - density cores , but their cores are systematically larger than those obtained by arepo and our disph .
the averaged `` sb '' profile of the temperature shows a sign of central decrease , since it is the average of sph ( decreasing ) and mesh ( increasing ) profiles .
we can see the same tendency in the entropy profile ( the bottom - right panel ) . in figure
[ fig : entropy : comparison ] , we plot the entropy profiles of our low - resolution runs , as well as those of our high - resolution runs and three results from the literature ( `` sb '' , `` arepo '' and `` nyx '' ) .
we can see that for disph runs , the difference in resolution does not make much difference in the entropy profile ; the entropy profiles with disph are consistent with that obtained by a moving mesh code arepo .
on the other hand , our low - resolution ssph run gave a central entropy significantly higher than that of our high - resolution ssph run .
our low - resolution ssph result is similar to those of the ssph simulations in @xcite and @xcite .
thus , it is clear that the `` core '' in these previous ssph results is due to the limitations in the numerical resolution . from this figure
, we find that the central entropy in the high - resolution disph run is slightly higher than that in the low - resolution disph run , although we saw the opposite sense from the entropy maps ( figure [ fig : virial : entropy ] ) .
this is because there is an offset of @xmath74 between the position of the entropy minimum and the plot center ( the density weighted center ) in the high - resolution disph run , and it makes the rather flatter central entropy profile .
thus , there is no discrepancy . in order to assess which parameters , i.e. , mass and spatial resolutions , are more crucial to the final entropy profile of the cluster , we carried out two extra models with disph and ssph which mix resolutions ; ( 1 ) with the high mass / low spatial resolutions ( `` mixed resolution 1 '' ) and ( 2 ) with the low mass / high spatial resolutions ( `` mixed resolution 2 '' ) . as shown in figure [ fig : entropy : mixed ] , the former run reproduced the entropy profile of the high - resolution ssph run , while the latter run did that of the low - resolution ssph run .
a slight difference is found only in the very central region ( @xmath75 ) .
hence , in the ssph runs , the central structure of the entropy profile is sensitive to the small scale power of the initial density fluctuations .
there is no significant influence on the results with disph .
the good agreement between results with disph , arepo , and gizmo is quite encouraging .
however , the analysis so far is only limited at the date of @xmath61 . in the next subsection
, we compare the results obtained by disph and ssph methods deeply , by focusing on the formation process of the cluster .
the cluster grew rapidly while @xmath76 , and then experienced a major merger around @xmath77 , and evolved mildly until @xmath61 .
we follow these typical phases of evolution to understand how and when the entropy core and cusp are established .
figure [ fig : entropy : threeepochs ] shows the radial entropy and density profiles for the high - resolution disph and ssph runs .
we here plot them for three epochs , before the major merger ( @xmath78 ) , after the major merger ( @xmath79 ) , and at the end of the simulation ( @xmath61 ) . for the run with disph , at @xmath78 , the entropy profile has a relatively small core .
then , the core entropy and core size increase and these quantities are kept unchanged until @xmath61 .
the entropy profile at @xmath79 is comparable to that at @xmath61 ; the last major merger event triggers this core entropy increase ( see below ) .
the entropy of the intermediate region of @xmath80 slightly increased during @xmath81 .
the evolution of the density profile is similar , but in the opposite direction . the core density decreases by almost a factor of three from @xmath78 to @xmath79 , and
it remains unchanged until @xmath61 .
the evolution of the radial profile in the ssph run is quite different from that in the disph run . at @xmath78 , the entropy profile with ssph
has a small core which is comparable to that of the disph run .
this entropy core becomes larger until @xmath79 .
however the core entropy is much lower than that with the disph run . at @xmath61 ,
the entropy core vanishes nearly .
the density profile follows this evolution similarly but in the opposite direction . at the end of the simulation
the density profile has a cusp .
evolution of the radius of the entropy core and the averaged core entropy in the runs with disph and ssph are shown in figures [ fig : entropy : coreradius ] and [ fig : entropy : coreentropy ] .
the definition of the core radius is described in appendix [ sec : method : core ] .
the averaged core entropy is measured using the entropy of gas in the core radius .
their evolutions can be divided into two phases and the transition takes place after the major merger epoch ( @xmath82 ) . in the disph
runs , two results agree with each other very well . in the early phase ( @xmath83 ) , the radius of the entropy core increases from @xmath84 ( @xmath85 ) to @xmath86 ( @xmath82 ) and the averaged core entropy increases from @xmath87 ( @xmath85 ) to @xmath88 ( @xmath82 ) .
then the growth of the core radius is stopped and the core is essentially unchanged until @xmath61 . in the ssph
runs , the evolution is completely different from those of disph runs .
when we compare the high resolution runs , the core radius of the ssph run is smaller than that of the disph run in the initial phase ( @xmath89 ) .
major merger triggered the rapid increase , but at @xmath82 the core is still smaller than that of disph runs .
second , the core size shrinks and the averaged core entropy decreases in the late phase ( @xmath90 ) .
these figures suggest that the low - entropy material is supplied to the central region , most likely via minor mergers in the late phase .
the low resolution ssph run follows the evolution of the high resolution one , although its goes between disph runs and the high resolution ssph runs because of lower resolution . in [ sec :
majormerger ] and [ sec : minormerger ] , we further investigate the evolution of the cluster s central entropy induced by the major and minor mergers .
figure [ fig : entropy : merger : disph ] shows the evolution of the distributions of pressure and entropy in the cluster in the high resolution disph run during the major merger phase ( @xmath91 ) . a smaller cluster consisting of the low - entropy material approaches from the top - right corner ( @xmath92 ) , it merges with the main cluster ( @xmath93 ) and after several crossing times these two clusters completely merge to form a single cluster with the relaxed structure ( @xmath94 and @xmath95 ) . in this run , the entropy at the cluster center increases due to shocks ( see bottom panels ) . before the merging event ,
the central entropy is lower than @xmath73 , but it becomes higher than @xmath73 after the merger event ( see also figure [ fig : entropy : coreentropy ] , @xmath96 at @xmath97 whereas @xmath98 at @xmath82 ) .
the pressure maps are smooth throughout this event ( top panels ) . in the ssph run
, we also observe the increase of the central entropy whereas the absolute value is lower than that in the disph run , as we see figure [ fig : entropy : merger : ssph ] .
there are sharp edges in the distribution of the low - entropy ( cold ) gas clumps , and therefore the mixing of low- and high - entropy components is much weaker in the ssph run compared to that in the disph run .
pressure maps show sharp gaps which are not found in those in the disph run .
thus , these gaps are outcomes of the unphysical surface tension of ssph , resulting in the suppression of the entropy generation due to shocks . here
, we focus on the late stage of the evolution of the cluster .
figure [ fig : entropy : merger : minor ] shows the evolution of the radial entropy distribution
. the main sequence of the entropy distribution , where the relative fraction is high , corresponds to the radial entropy profile we saw in , e.g. , figure [ fig : entropy : comparison ] . in addition to the main sequence , there are a number of low entropy components .
these low - entropy components are clumps in and around the cluster .
the evolution of the cold gas clumps are quite different in the disph run and ssph run . in the case of
ssph run ( bottom panels ) , there are many clumps with minimum entropy around @xmath99 , within the distance range @xmath100 . on the other hand , in the case of the disph run , there are only a few clumps within the distance @xmath101 , and their minimum entropy is much higher .
thus , in the case of the ssph runs , cold gas clumps survive in the cluster and fall to the cluster center , forming low - entropy core , while in the case of the disph run , cold gas clumps are disrupted before they reach to the center of the cluster . in order to clarify the difference of the late stage evolution of the disph run and that of the ssph run
, we here focus on the evolution of one clump . for this analysis
, we first pick up low entropy component within @xmath59 .
the threshold entropy is @xmath102 which is slightly lower than the core entropy of the disph runs at @xmath61 . with this threshold
, we found a number of low entropy clumps . in order to select one representative clump from them
, we imposed the following conditions : ( 1 ) the clump is approaching to the cluster center , ( 2 ) the mass is sufficiently large so that we can track its evolution , ( 3 ) the clump reaches to the center of the cluster before @xmath61 , and ( 4 ) the clump can be found in both runs at the same position .
the representative clump we picked up is found at @xmath103 and its total mass is @xmath104 at @xmath105 .
figure [ fig : target : disph ] shows the evolution of this low - entropy clump in the high - resolution disph run . from the particle distribution maps ( upper panels ) , we can see that this representative clump enters the cluster center forming a bow - shock .
its front surface is being stripped due to fluid instabilities , resulting in the complete destruction of the clump by @xmath106 ( recall the blob test in * ? ? ?
the pressure distribution across the interface between the clump and the intracluster medium is always smooth .
figure [ fig : target : ssph ] shows the evolution of the same clump in the high - resolution ssph run .
there is a clear gap both in the particle and pressure distributions in the front of the clump .
this gap is induced by the unphysical surface tension , protecting this clump from the development of fluid instabilities at the surface and ram - pressure stripping .
thus , the low entropy gas in this clump can sink to the cluster center .
we compare the evolutions of this representative clump in disph and ssph runs in figure [ fig : target : evolutions ] .
top , middle , and bottom panels are the distance from the cluster center , the size , and the averaged entropy of the gas particles of the clump , respectively . before the pericenter passage , clumps in two runs are almost identical
. when it passed the pericenter , the orbital decay starts .
the orbital decay in the ssph run is much faster than that in the disph run .
clumps expand when passing the pericenter .
the clump in the disph run is more extended compared to that in the ssph run .
these two results tell us that the clump in the ssph run keeps a compact structure much longer .
the increase of the mean entropy starts slightly before the pericenter passage in both runs . at @xmath61 ,
the mean entropy of the clump in disph is @xmath107 higher than that in ssph .
this indicates that the shock heating is more efficient in the disph run . however , behind the fact that ssph has unphysical surface tension , we should say that the shock heating in ssph is more inefficient .
disph can capture the intrinsic shocks .
this difference in the shock heating efficiency explains why cold gas clumps can reach to the center of the cluster in the ssph run but are disrupted in the disph run .
this tendency that the clumps in the ssph run survive longer at the center of the cluster compared to those in the disph run can be seen in figure [ fig : target : stack ] . here
, we used subfind clumps ( see appendix [ sec : method : subfind ] ) and stacked data during @xmath108 ( total 17 snapshots ) . generally , as clumps move closer to the center of the cluster , they loose their masses due to tidal and ram - pressure stripping . at the same distance from the cluster center , in particular for @xmath109 , we can see the clear tendency that clumps in ssph are more massive than those in disph .
thus , the evolution of the inner part of the cluster strongly affected by the choice of the sph scheme .
while clump surviving time is different , there is no significant difference in mass functions with different sph schemes ( see appendix [ sec : results : massfunction ] ) .
it has been pointed out by @xcite that the cluster core entropy decreased at the low-@xmath110 with ssph .
they measured the evolution of entropy at the central region ( @xmath111 ) of clusters of galaxies in a @xmath4cdm universe .
they found that the core entropy of the ssph run decreased continuously for @xmath112 whereas those of amr and sphs runs were roughly constant .
although they did not follow the individual clumps , they explained that the change of the central entropy found in low-@xmath110 period is due to the accretion of the low - entropy clumps induced by the minor mergers .
our study supports their result and this process works in the evolution of the santa barbara cluster in previous studies as well .
recently , the ac term has become widely used in sph simulations in order to remove the unphysical surface tension ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
, we investigate the effects of ac on the cluster formation and evolution .
similar studies are found in the literature ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
according to the numerical experiments by @xcite and @xcite , it is expected that the entropy core appears if the ac term is introduced into ssph and the core size and core entropy depend on the maximum value of the conduction control parameter @xmath113 .
thus , in this section , we highlight the contribution of @xmath113 to the thermal structure and the entropy profile . here , we adopt the following functional form for the ac : @xmath114 where @xmath115 , @xmath116 , @xmath117 is pressure , and @xmath118 $ ] .
following @xcite , we evaluate the ac coefficient of particle @xmath25 , @xmath119 using the following equation ; @xmath120 where @xmath121 is evaluated by the sph manner and @xmath119 is allowed to evolve from @xmath122 to @xmath113 .
this ac term is essentially the same as those adopted in the previous studies ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
we tested several functional forms and switches and found that the conclusion in this subsection does not affected by them .
we show five high - resolution ssph runs with different values of @xmath123 : @xmath124 and @xmath125 .
figure [ fig : ac : temp ] shows the temperature maps of five runs with the ac term , as well as that of the run without ac . from this figure
, we can see that the temperature structure gets blurred when @xmath113 increases .
we find that there is a similar effect in both the density and entropy maps .
this blurring effect has an influence on the entropy profile of the cluster , as we see next .
figure [ fig : ac : entropy ] shows the radial entropy profiles with and without ac . apparently , the entropy profile is affected by ac .
the entropy profile with @xmath126 is cuspy ; it has a slightly higher entropy than that without ac in @xmath127 .
on the other hand , those with @xmath128 have cores .
these core entropies increase with increasing @xmath129 and the increase stalls when @xmath130 .
the core entropy with @xmath131 is comparable to those with disph and arepo whereas that with @xmath132 is rather close to that obtained by a mesh code . in our test , unlike previous study @xcite , the core entropies with @xmath130 are slightly lower than those obtained by mesh codes .
this difference might come from the detailed implementations .
time evolutions of averaged core entropies for five ac runs are shown in figure [ fig : ac : entropy : core ] .
the overall evolutions of the runs with @xmath133 are similar to those of disph runs ; the increase of the core entropy is fast until @xmath82 and then it stops . on the other hand ,
the evolution with @xmath134 is close to that without ac , whereas this run has a slightly higher entropy within @xmath135 .
the final core sizes are @xmath136@xmath137 for the runs with @xmath138 ( recall that they are @xmath139 in disph runs ) .
although ssph runs with ac ( @xmath138 ) have slightly larger entropy cores , the effect of the ac term looks similar to that of disph ; the essential difference is that ac requires the new free parameter @xmath123 .
since the numerical results depend on this parameter , one needs to pay attention to determine its value .
it is of course possible that the calibrated @xmath113 for one experiment is inadequate for another experiment .
in this paper , we studied the formation of the entropy core in the santa barbara cluster .
previous studies ( e.g. , * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ; * ? ? ?
* ) have demonstrated that simulations with eulerian mesh codes make the entropy core in the cluster center while those with lagrangian sph codes do not .
the original paper @xcite argued that the origin of this difference came from the different treatment of shocks in the sph and mesh codes .
however , both eulerian mesh codes and lagrangian sph codes have their own , intrinsic limitations which might affect the entropy evolution .
this implies that neither mesh results nor sph results is correct . @xcite and @xcite reported that new lagrangian fluid schemes made entropy cores but the depth of their cores is deeper than those obtained by eulerian codes . the clusters simulated with disph formed prominent entropy cores and its size and absolute value of the core entropy was insensitive to the adopted resolutions . during the cluster formation , a number of low entropy clumps accreted and these clumps brought low entropy materials to the cluster center . in the disph runs , the ram pressure stripping and fluid instabilities disrupted these clumps efficiently in disph runs .
the entropy of these clumps increased due to hydrodynamical shock and they built the entropy core .
the size of the entropy core at @xmath61 is @xmath139 and the depth of that is @xmath140 .
these values are comparable with those obtained by the original version of the moving mesh code @xcite and the mesh free code @xcite .
the values of the core entropy obtained in these simulations are about unity lower than those with eulerian mesh codes .
this systematic difference is probably due to the numerical diffusion intrinsically existing in eulerian codes ( e.g. , * ? ? ?
* ; * ? ? ?
* ) . in principle
, the effect of the numerical diffusion can be reduced by increasing the spatial resolution @xcite . however , whether this strategy is really useful for cosmological simulations or not is unclear since this approach is quite time - consuming .
we were able to reproduce the cuspy entropy profile when we used ssph and the results with ssph depended strongly on the adopted mass resolution .
when we employ low mass resolution , there is a small core which is comparable with the previous simulations .
when we adopt the high mass resolution , the central entropy became much lower and the cusply profile appeared . by following the evolution of the central entropy , we found that the central entropy in ssph runs affected by the minor mergers involving the low - entropy gas .
low - entropy gas in simulations with ssph is `` protected '' against ram - pressure stripping , as found by @xcite .
the evolution of low - entropy clumps in disph is completely different from that in ssph .
the cuspy entropy profile found in the ssph runs is artifact . we can obtain the entropy core in the santa barbara cluster with just changing the volume element of the formulation and without introducing any diffusions .
there are several studies in which entropy core was obtained by introducing dissipations to sph @xcite . in their studies
, they could obtain cored entropy profiles .
we also confirmed it by our numerical experiments .
as is reported by previous studies , the core size depended on the diffusion coefficient of the conductivity .
our method has advantages over these methods since there is no need to calibrate the diffusion coefficients . in addition
, there is no time and spacial scales which controls the degree of the dissipation strength if we used disph , since formulation of disph itself can remove the unphysical surface tension . we thus conclude that disph is a good alternative to ssph for the cosmological structure formation .
there is room to improve the implementation of the av term and switches .
for instance , a sophisticated switch is important in order to deal with a rotating system @xcite .
recently , @xcite showed a survey of the implementation of the av . in their study
, they showed that the run with the combination of the von - neumann - richtmyer - landshoff type av term velocity gradient @xcite can maintain the keplerian disk for @xmath141 orbits .
we need to investigate the feasibility of these methods in structure formation simulations .
we thank the anonymous referee .
her / his insightful comments improve our manuscript greatly . t.r.s .
thanks takashi okamoto and kohji yoshikawa for useful discussion . t.r.s . also thanks lucy kwok and junko saitoh who helped in writing the manuscript .
numerical simulations were carried out on the cray xc30 system in the center for computational astrophysics at the national astronomical observatory of japan .
this work is supported by grant - in - aid for scientific research ( 26707007 ) of japan society for the promotion of science and strategic programs for innovative research of the ministry of education , culture , sports , science and technology ( spire ) .
this work is supported in part by mext spire and jicfus .
the philosophy of the introduction of ac is to ensure all physical quantities will be smooth everywhere . at a contact discontinuity , ssph makes a pressure blip if the internal energy does not have a smoothed profile consistent with the smoothed profile of density . to guarantee the consistent profile of the internal energy , ac spreads the internal energy until the pressure profile becomes smooth .
this term works very well in the standard tests and widely used .
however , one meets a difficulty when one applies ac to a contact discontinuity consisting of a fluid with different chemical compositions .
consider the case in which there are two contacting fluids and they have different chemical compositions . here
, we assume that they have different mean molecular weights , @xmath142s .
thus , the internal energy is a function of @xmath142 and temperature @xmath71 ; @xmath143 .
moreover , these two fluids are initially in the pressure and temperature equilibrium state .
disph can reproduce the original pressure and temperature equilibrium state without any difficulty . on the other hand
, ssph can not reproduce it ; a pressure jump appears across the contact interface .
ssph with the ac term gives a pressure equilibrium state by changing the internal energy of particles around the contact interface .
since @xmath143 , this change of @xmath144 induced by ac is regarded as the changes of @xmath71 and @xmath142 .
unfortunately , we do not know an appropriate procedure to spread @xmath71 and @xmath142 .
hence , we can not predict exact quantities of @xmath142 and @xmath71 at the contact interface .
there are two possible limits : ( 1 ) @xmath71 changes but @xmath142 does not , and ( 2 ) @xmath142 alters but @xmath71 does not .
the former leads to undesirable chemical reactions if one is solving the chemical reactions , since they depend on @xmath71 .
the latter is the compulsive mixing of chemical compositions .
we show a simple , one - dimensional numerical experiment regarding this problem .
the initial condition is as follows .
the computational domain is @xmath145 with a periodic boundary condition .
the fluid at @xmath146 has @xmath147 while the other has @xmath148 .
both pressure and temperature have constant values in the whole region .
since @xmath149 , the density and internal energy have different values in these two sub - domains . here
the initial pressure and temperature are unity and @xmath150 .
the density is normalized so that @xmath151 .
we solved this system until @xmath152 sound crossing time .
we used two schemes : one was disph and the other was ssph with the ac term . here , we adopt the ac term described in [ sec : results : ac ] and @xmath153 .
figure [ fig : ac ] shows the results of ssph with the ac term and disph at time @xmath154 ( about 100 crossing time ) . in the ssph run with the ac term , the initial pressure jump is smeared by smoothing the distribution of the internal energy ( the top - right panel in figure [ fig : ac ] ) .
if we consider this change of the internal energy as the change of the temperature , we have the temperature distribution with jumps at the contact discontinuities shown in the middle - right panel . on the other hand ,
if we regard it as the change of @xmath142 , we obtain the smoothed distribution of @xmath142 as shown in the bottom - right panel . in disph
, there is no difficulty in dealing with this system ( panels in the left column ) .
a system consisting of materials with different chemical compositions is not an unphysical situation .
for instance , for a giant impact simulation , one solves collisions of core(iron)-mantle(silicon based rock ) planet embryos @xcite . at the core - mantle boundary
, there is a jump of the composition .
in addition , at the contact interface at the colliding time there is also a jump of the chemical composition .
if we use the ac term for this simulation , the boundary materials are mixed and/or the temperature at these boundaries changes .
disph for a non - ideal gas @xcite can deal with these boundaries without any difficulty @xcite .
the time integration of a single step from @xmath155-th step to @xmath156-th step where the time step is @xmath157 is carried out by the following procedure : 1 .
advance the velocity @xmath158 from @xmath155-th step to @xmath159-th step using the acceleration @xmath160 : @xmath161 2 .
drift the position @xmath162 from @xmath155-th step to @xmath156-th step using @xmath163 : @xmath164 3 .
evaluate the predictor of the velocity at @xmath156-th step using @xmath160 : @xmath165 4 .
evaluate the predictor of the specific internal energy at @xmath156-th step using the time derivative of @xmath166 , @xmath167 : @xmath168 5 .
compute @xmath169 and @xmath170 using @xmath171 , @xmath172 , and @xmath173 .
advance @xmath163 by the rest of the half step using @xmath169 : @xmath174 7 .
compute @xmath175 using both @xmath167 and @xmath176 : @xmath177 \delta t.\ ] ] the manner to integrate the internal energy described above is heun s method ( or the modified euler s method or the second order runge - kutta method ) .
thus , our integration scheme is categorized as the second order method . for dm particles ,
this time integration scheme is reduced the standard second order symplectic scheme , the leap - frog scheme . as a demonstration
, we show the results of the adiabatic collapse test with this time integration scheme .
this test is one of the standard benchmark tests of self - gravitating fluid @xcite .
a number of simulation codes showed results of this test ( e.g. , * ? ? ? * ; * ? ? ?
* ; * ? ? ?
the typical error of the total energy in this test is less than @xmath178% .
the initial condition of this test was generated as follows .
first , we prepared gas particles located on uniform grid points .
then , by stretching their relative distances from the center of the coordinates , we made the gas distribution with a radial density profile of @xmath179 , where @xmath180 is the distance from the center of the coordinates .
the gas particles in @xmath181 are adopted to make a gas sphere .
we assumed that they do not have a bulk velocity at the beginning of the simulation .
the total mass and the gravitational constant are unity .
the specific initial thermal energy is @xmath182 and @xmath55 .
since the initial kinetic energy is zero and the thermal energy is less than the absolute value of the potential energy , this gas sphere collapses due to self - gravity and eventually reaches a state of equilibrium . here , we represented this gas sphere with the 61432 equal - mass sph particles .
the gravitational softening length was set to @xmath183 .
we carried out four runs .
two are disph and ssph , which were used in this paper . in these runs ,
the kernel size was determined so that the neighbor number is in the range of @xmath58 .
however , it is pointed out that the use of the constant neighbor number often makes sudden change of the interaction radius , resulting in the fluctuations of physical quantities .
thus , the other two runs adopted the smoothed neighbor number method for the evaluation of kernel size @xcite . here , both disph and ssph were used .
we express our fiducial cases as disph and ssph , and the other two cases with the smoothed neighbor number method as disph(s ) and ssph(s ) .
the wendland kernel c4 was adopted .
the self - gravity was solved by using the tree with grape method .
the opening angle was set to @xmath54 .
time step for each particle is determined following @xcite .
figure [ fig:3dcollapse : evolution ] shows the evolution of radial profiles of density , pressure , and radial velocity of the disph run .
three representative epochs are adopted . except for the central region ( @xmath184 ) , our result is comparable with a 1d ppm result .
the other three cases , ssph , disph(s ) , and ssph(s ) , show almost identical results . in figure [ fig:3dcollapse : all ] , we show time evolutions of the kinetic , thermal , potential and total energies . again , we show the result of the disph run .
the overall evolution is comparable with that obtained in previous studies and the other three cases show identical results .
figure [ fig:3dcollapse : total ] represents time evolutions of the total energies in four runs .
these total energies change significantly at time @xmath185 when the gas sphere collapses , while they keep almost a constant value at other times .
we define the energy error as follows : @xmath186 where @xmath187 and @xmath188 are the total energy of a system at time @xmath189 and @xmath190 , respectively .
energy errors evaluated by the above equation are 0.19% for disph , 0.22% for ssph , 0.14% for disph(s ) , and 0.16% for ssph(s ) , respectively .
thus our time integration scheme works well .
the fact that there is no significant difference among them indicates that the choices of the definition of the neighbor numbers and sph types are not crucial for the energy conservation in our simulations .
in order to compare sizes of entropy core and their time evolutions among different simulations , we need a methodology to evaluate a core size from an entropy profile .
as is shown in the text , the evolutions of core size and entropy are highly time - variable . in order to follow this dynamically evolving structure
, we adopt the technique used in the field of stellar cluster simulation .
below , we describe our method to define the entropy core .
first , we calculate the radially averaged entropy profile ; it is expressed as @xmath191 to @xmath65 from the density center . the constant interval with the logarithmic scale
we calculate the entropy of each particle and add it to a bin which covers the position of the particle .
we obtain the radial entropy profile of the cluster by taking the average of entropy in each bin .
the averaged entropy at the given @xmath192 is calculated by the linear interpolation of the binning values .
if @xmath193 , we use @xmath194 as the averaged entropy at the given @xmath192 . ] , where @xmath192 is the distance from the density center , @xmath195 .
we , then , pick up particles of which entropy is in the range of @xmath196 and evaluate the core radius using these particles .
the reason why we sampled particles from the narrow region is to exclude the contamination of small , low - entropy clumps ( see also figure [ fig : entropy : merger : minor ] ) . without this process , we were unable to obtain a reasonable size of the entropy core
. the following equation is used in order to evaluate the core radius : @xmath197 where @xmath198 is the entropy of particle @xmath199 and @xmath200 .
the index @xmath199 runs particles of which entropy are in the range of @xmath201 and @xmath202 .
we use a very strong power of the inverse of the entropy as the weight function to determine the entropy core .
the outer part of the entropy profile of clusters of galaxies , typically in the range of @xmath203 , follows @xmath204 @xcite .
therefore , a weight which is stronger than @xmath205 is suitable in order to evaluate of the core .
after intense tests , we found that the weight , @xmath206 , is suitable in order to evaluate the core radius of the radial entropy profile .
we adopt the subfind algorithm @xcite in order to extract self - bound clumps in the santa barbara cluster .
the procedure is as follows .
first , we calculate the density of all particles within @xmath207 using eq .
the density of gas particles is evaluated by counting the contribution of gas particles while that of dm particles is calculated by counting the contribution of dm particles .
the density of each particle is evaluated by the contribution from the nearest @xmath58 particles . here
, we refer these nearest particles `` local particles '' .
after the density evaluation , we sort all of particles in the descending order of the density .
we , then , identify isolate clumps following the density distribution .
we repeatedly compare the densities of particles with those in the densities of their local particles from the highest to the lowest density particles and apply the following operation . here
, we focus a particle @xmath25 . if the particle @xmath25 is the highest density particle in its local particles , we set the particle @xmath25 as the peak of an isolate clump ( the core of a new clump ) .
if the particle @xmath25 is the second highest density particle or it has two higher density particles which are in the same clump , we add the particle @xmath25 to the clump which includes the highest density particle . if the particle @xmath25 has more than two higher density particles and the two highest density particles are in different clumps , we tag these two clumps as _ the subfind clump candidates _ since the particle @xmath25 is at the saddle point which separate two clumps ( two density peaks ) .
then , we merge these clumps with a single larger clump and attach particle @xmath25 to this clump . the last operation is necessary in order to extract subfind clump candidates which are located at the envelop of this merged clump . as the final step , we remove unbound particles from the subfind clump candidates iteratively .
we first calculate the total energy ( the self - gravitational potential and the kinematic energy where the mean velocity of each clump is set to zero ) of each particle in a clump . then if the clump includes particles of which total energy is larger than zero
, we remove these particles from the clump .
we do not remove more that @xmath50 of the particles at once so that we can carry out this process stably .
we continue this procedure until the clump consists only of the bound particles .
we adopt clumps which contains more than 64 bound particles .
we apply this procedure to all clumps and get a full catalog of subfind clumps .
in this section we investigate the mass functions of substructures .
the subclumps are extracted using the subfind algorithm ( see [ sec : method : subfind ] ) .
figure [ fig : massfunction ] shows mass functions of substructures .
mass functions of the runs with the same resolutions have almost identical profiles .
all of mass functions asymptotically follow the power law profile with the index of @xmath208 .
it is not surprising that there is no impact on substructure mass functions with different schemes , since the amount of the baryonic component is @xmath209 of the total mass .
mass functions of the baryonic component is shown in figure [ fig : gasmassfunction ] .
not all of substructures hold the baryonic component due to the stripping .
thus , the number of baryonic substructures is very small compared to that of the total substructures .
even though the evolution of the gas clumps in the central area of the cluster is quite different for two runs , this difference is little or no effect on the mass function .
this is probably because in either case that lifetime of gas clump in the central area is short .
our mass functions do not show convergence with different mass resolutions .
we have checked mass functions with mixed resolutions and found that , at least toward the high mass end , the functional form of mass functions depends on the mass resolution .
thus , the discrepancy between high - mass resolution runs and low - mass resolution runs comes from the non - linear effect induced by the smallest scale density fluctuations . | the santa barbara cluster comparison project @xcite revealed that there is a systematic difference between entropy profiles of clusters of galaxies obtained by eulerian mesh and lagrangian smoothed particle hydrodynamics ( sph ) codes : mesh codes gave a core with a constant entropy whereas sph codes did not .
one possible reason for this difference is that mesh codes are not galilean invariant .
another possible reason is the problem of the sph method , which might give too much `` protection '' to cold clumps because of the unphysical surface tension induced at contact discontinuities . in this paper , we apply the density independent formulation of sph ( disph ) , which can handle contact discontinuities accurately , to simulations of a cluster of galaxies , and compare the results with those with the standard sph .
we obtained the entropy core when we adopt disph .
the size of the core is , however , significantly smaller than those obtained with mesh simulations , and is comparable to those obtained with quasi - lagrangian schemes such as `` moving mesh '' and `` mesh free '' schemes . we conclude that both the standard sph without artificial conductivity and eulerian mesh codes have serious problems even such an idealized simulation , while disph , sph with artificial conductivity , and quasi - lagrangian schemes have sufficient capability to deal with it . |
canine cutaneous tumors that consist of clear or vacuolated cells are uncommon and
include balloon cell melanoma , clear cell basal carcinoma , sebaceous carcinoma ,
apocrine sweat gland adenoma clear cell variant , clear cell trichoblastoma and
canine cutaneous clear cell adnexal carcinoma
.
canine cutaneous clear cell adnexal carcinoma has been described as
clear cell hidradenocarcinoma
and follicular stem cell carcinoma
, as first proposed by schulman et al . in 2005
.
this neoplasm does not differentiate into a single , special cutaneous
adnexa , but has multilineage potential that enables it to differentiate into
multiple cutaneous adnexa
.
immunohistochemical examination shows that neoplastic cells coexpress
cytokeratin ( ck ) and vimentin , indicating that the neoplasm may be derived from
follicular stem cells
.
follicular stem cells in dogs differentiate into cutaneous adnexa , such
as the inner and outer root sheaths , sebaceous glands and apocrine sweat glands
with different ck isoform expression in the respective cutaneous adnexa
.
these differences in ck expression are useful for examining divergent
adnexal differentiation of tumor
. in this paper , we report the histological and immunohistochemical findings of a
tumor in the lower lip of 14-year - old male castrated shih tzu that was diagnosed
with cutaneous clear cell adnexal carcinoma displaying several characteristic
immunohistochemical features .
we show divergent adnexal differentiation of the
neoplastic cells and compare the morphology with previously reported canine
cutaneous clear cell adnexal carcinomas .
the tissue specimen was fixed in 10% neutral formalin and embedded in paraffin or
optimal cutting temperature ( o.c.t . ) compound ( sakura finetek , tokyo , japan ) . a
block embedded in o.c.t .
paraffin
sections were stained with hematoxylin and eosin and reacted with periodic acid
schiff ( pas ) .
table
1 shows the primary antibodies used in this study . as secondary
antibodies , we used peroxidase - conjugated anti - mouse ( histofine simple stain
max - po(m ) , nichirei , tokyo , japan ) and peroxidase - conjugated anti - rabbit
( histofine simple stain max - po(r ) , nichirei ) immunoglobulin ( ig)g .
immunoreactions were visualized by diaminobenzidine , and the sections were
counterstained with mayer s hematoxylin . to examine coexpression of ck and
vimentin within the neoplastic cells , anti - ck ( clone ae1/ae3 ) and
anti - ck and
anti - vimentin antibodies were labeled with affinity - purified goat anti - mouse igg
fluorescein isothiocyanate ( ey laboratories , san mateo , ca , usa ) and
affinity - purified goat anti - mouse igg ( rhodamine conjugate , chemicon , temecula ,
ca , usa ) , respectively . a cut surface of the formalin - fixed neoplastic mass ( 8810 mm ) .
a ) the tumor
mostly consists of round or polygonal neoplastic cells with clear or
vacuolated cytoplasms .
c ) fine glycogenic granules are present in
the cytoplasm of the clear neoplastic cells .
bar=20
m . the excised mass was 8810 mm in size , and its cut surface contained multiple
lobules and was white ( fig .
histologically , the neoplasm was located in the dermis and was composed of
lobular structures separated by thin fibrous stromal tissues .
the cells varied in size and
were characterized by clear or vacuolated cytoplasms with round to oval nuclei
( fig .
2c ) ,
which disappeared with diastase treatment . all neoplastic cells were negative
for sudan iii .
there were no follicular papillary mesenchymal bodies , but there
were many tubular structures with or without pas - positive basement membrane - like
structures within the neoplasm ( fig .
3 a ) immunostaining for pan - ck ( ae1/ae3 ) : positive neoplastic cells
are diffusely distributed .
b ) immunostaining for pan - ck ( cam 5.2 ) : most neoplastic
cells are positive , and tubular structures are strongly positive .
c ) immunostaining for pan - ck ( kl1 ) : positive neoplastic cells
including tubular cells are scattered .
d ) immunostaining for
ck-7 : some of the neoplastic cells forming tubular structures are
positive .
g )
immunostaining for ck-15 : a few clear or vacuolated neoplastic
cells are weakly positive .
i ) immunostaining for vimentin : most
neoplastic cells , except tubular structures , are positive .
the neoplastic cells are mostly positive
for -sma ; however , neoplastic cells in a nodule ( * ) are barely
positive .
none of the tubular structures are positive just for vimentin
( arrows ) .
table 2 shows the results for the special
stains and immunohistochemical staining of the tumor and normal skin tissues .
immunohistochemically , the neoplastic cells were positive for pan - ck ( ae1/ae3 ,
kl1 , cam 5.2 ) , ck-7 , ck-8 , ck-14 , ck-15 , ck-18 , vimentin and -sma ( figs .
the proportion of -sma - positive
cells was more than 75% of the neoplastic cells .
however , -sma - positive cells
were rarely observed in a few neoplastic lobules ( fig .
a ) immunostaining for pan - ck ( ae1/ae3 ) : positive neoplastic cells
are diffusely distributed .
b ) immunostaining for pan - ck ( cam 5.2 ) : most neoplastic
cells are positive , and tubular structures are strongly positive .
c ) immunostaining for pan - ck ( kl1 ) : positive neoplastic cells
including tubular cells are scattered .
d ) immunostaining for
ck-7 : some of the neoplastic cells forming tubular structures are
positive .
g )
immunostaining for ck-15 : a few clear or vacuolated neoplastic
cells are weakly positive .
i ) immunostaining for vimentin : most
neoplastic cells , except tubular structures , are positive .
the neoplastic cells are mostly positive
for -sma ; however , neoplastic cells in a nodule ( * ) are barely
positive . bar=100
tubular structures in the neoplasm were positive for pan - ck ( ae1/ae3 , cam 5.2 ,
kl1 ) , ck-7 , ck-8 , ck-14 , ck-18 , and partly positive for vimentin , but negative
for -sma ( figs . 3
, 4 ) .
a few neoplastic cells were positive
for s-100 and pgp9.5 , but negative for nse and melan a. mhc class ii - positive
cells were present in the neoplasm , which might represent dermal dendritic
cells .
double - labeled immunofluorescence staining revealed that most neoplastic
cells were double - positive for ck and vimentin ( fig .
histologically , neoplastic tubular structures were frequently observed , suggesting
that neoplastic cells differentiated into apocrine sweat glands .
however , the
immunohistochemical results showed that the neoplastic cells expressed specific
ck isoforms of several cutaneous adnexa .
the tumor cells expressed ck-8 and
ck-18 , and had glycogenetic granules in the cytoplasm . in normal canine skin ,
glycogenetic granules are known to exist in the outer root sheath of
normal canine skin .
this suggests that the present tumor had differentiated into
the outer root sheath and into the apocrine sweat gland .
in addition , the
neoplastic cells expressed pan - ck ( kl1 ) and ck-14 . in normal canine skin , pan - ck
( kl1 )
is expressed in the superficial layer of the epidermis and inner root
sheath , and ck-14 is expressed in the basal layer of the epidermis , outer root
sheath , inner root sheath , sebaceous gland and myoepithelial cells of the
apocrine sweat gland
. meanwhile , the present neoplasm was negative for sudan iii .
immunostaining
indicated that the present tumor differentiated into the epidermis , inner root
sheath , outer root sheath and apocrine sweat gland and that it also coexpressed
ck and vimentin .
this supports the hypothesis that clear cell adnexal carcinoma
derives from the follicular stem cell
. in previously reported cases of clear cell adnexal carcinomas ,
however , in the present tumor , many neoplastic cells expressed -sma .
because actin is the predominant component of contractile microfilaments , which
are responsible for cell motility and transport , -sma might play a role in cell
migration and/or morphologic changes in the lower portion of the follicle during
the hair cycle
. in mouse experiments in vitro , cells were found to
express nestin in the bulge area and differentiated into neurons , glial cells ,
keratinocytes , smooth muscle cells and melanocytes
.
these studies suggest that cells in the canine bulge area can
differentiate into -sma - positive cells .
additionally , in normal canine skin ,
myoepithelial cells of the apocrine sweat gland are positive for -sma as well
as ck , indicating that some -sma - positive neoplastic cells in the present case
might have differentiated into myoepithelial cells .
apocrine sweat gland tumors
with prominent proliferation of the myoepithelium component are considered to be
a differential diagnosis due to their high positivity for -sma . however , most
neoplastic cells also expressed vimentin , which ruled out apocrine sweat gland
neoplasms .
moreover , the divergent differentiation of the neoplastic cells in
this case is not seen in other cutaneous tumors , including complex apocrine
sweat gland neoplasms . in a previous report of clear cell adnexal carcinoma ,
tumor cells were positive
for ck-8 and ck-18
, thus suggesting they differentiated into the outer root sheath and
apocrine sweat gland
.
other reports have shown that clear cell adnexal carcinoma is negative
for -sma
.
however , the present tumor was positive for ck-8 , ck-18 , pan - ck ( kl1 ) ,
ck-14 and -sma . additionally , the present tumor most likely differentiated into
the inner root sheath , outer root sheath and apocrine sweat gland ( glandular
epithelial cell and myoepithelial cell ) .
this indicates that clear cell adnexal
carcinoma has multilineage potential and differentiates into cutaneous adnexa
and that this differentiation trend and the extent are different in each
neoplasm .
recently , ck-15 , ck-19 , cd34 and cd200 have been shown to be human follicular stem
cell markers
.
canine hair follicles are reported to be more similar to human hair
follicles than those of mice when considering their architecture and size
. presumably , canine hair follicles could have stem cell machinery
analogous to human hair follicles
.
ck-15 and cd34 have been used as canine follicular stem cell markers in
a previous study
. in the present case ,
ck-15 was positive in only 1% of neoplastic cells ,
regardless of the fact that clear cell adnexal carcinoma is suspected to be a
neoplasm derived from follicular stem cells .
additionally , in normal skin , the
intermediate region of the outer root sheath was positive for ck-15 ( table 2 ) . in this study , it is clear that
the neoplastic cells probably differentiated into several adnexa . | cutaneous clear cell adnexal carcinoma was found in the right lip of a
14-year - old male castrated shih tzu .
histologically , the tumor mostly
consisted of neoplastic cells with clear or vacuolated cytoplasms and
contained frequent tubular structures .
neoplastic cells showed coexpression
of pan - cytokeratin ( ck ) and vimentin by double - labeled immunofluorescence
staining .
in addition , immunohistochemistry revealed that the tumor cells
were positive for pan - ck ( ae1/ae3 , kl1 , cam 5.2 ) , ck-7 , ck-8 , ck-14 , ck-15 ,
ck-18 , vimentin and alpha - smooth muscle actin ( sma ) with varied intensity
and positivity . among these marker proteins ,
sma was positive in 75% of the
tumor cells .
on the other hand , ck-15 , which is a specific marker of
follicular stem cells , was expressed in less than 1% of the tumor cells .
based on these findings , the tumor showed diverse differentiation in
apocrine sweat glands and the inner and outer root sheaths of hair
follicles , indicating the follicular stem cell to be the origin of this
tumor . |
cleft lip and palate is a craniofacial anomaly caused by failure in the fusion of embryonic facial processes1 .
it is the most common malformation , occurring in approximately 1 per 500 - 700 births and , this ratio vary considerably across ethnic grouping .
this congenital deformity results in esthetic and functional alterations , depending on the affected structures .
otological and hearing problems have a high prevalence in the population with cleft lip and palate compared with the unaffected population , because this malformation affects important structures in the tympanic ossicular chain , thereby predisposing to otitis media with consequent hearing loss .
therefore , special attention should be given to this aspect2
3
4 . during the initial consultation , the speech language pathologist and audiologist may consider possible diagnostic hypotheses on the basis of the child 's history and the parents ' complaint5 . earlier diagnosis of auditory difficulties in children results in better intervention and support in cognitive and social development . considering the importance of early diagnosis of hearing impairment and the knowledge of language development
, the situation with regards to identification and early diagnosis requires clarification . this may facilitate introduction and performance of actions that prevent delayed language development in children with hearing difficulties6 .
therefore , the purpose of this study was to verify the association of auditory complaints with the findings of the conventional audiologic assessment in children with cleft lip and palate who were treated at a specialized hospital in a city located in the state of so paulo .
the present study was approved by the ethics committee of bauru school of dentistry ( fob / usp ) , process number 049/2008 .
this retrospective study utilized 1000 randomly selected charts of patients with cleft lip and palate who underwent surgical repair between 1988 and 1995 .
we verified data regarding gender , age , speech , language , and audiologic history , in addition to data concerning conventional audiologic assessment ( pure - tone audiometry ) .
the patient 's audiologic history was verified in the interview , with an emphasis on hearing complaints . in the audiologic assessments we verified the presence or absence and the type of hearing loss .
we excluded medical charts with records of inconsistent audiologic responses and charts with missing data for any of the audiologic evaluations considered .
of the 393 charts studied , 262 ( 66.6% ) belonged to boys and 131 ( 33.3% ) belonged to girls aged between 4 years and 10 years 11 months .
the qui - square test was used for the statistical analysis . the minimum level of significance
of the 393 patients , 239 presented hearing loss in one or both ears , which was conductive , mixed , or sensorineural .
n , number of patients % , percentage of patients only 15 patients reported auditory complaints in the speech , language , and audiologic history ( 3.8% ) ; otorrhea ( n = 10 ) was the most frequent finding in these patients followed by otalgia ( n = 9 ) .
in contrast , 378 ( 96.18% ) did not report complaints regarding hearing ( table 2 ) .
n , number of patients % , percentage of patients among the 15 individuals who reported auditory complaints , there were 8 boys and 7 girls , and there was no correlation between the complaint and the gender ( p = 0.26 ) .
most patients with auditory complaints in the interview presented with hearing loss in at least one ear ( p 0.001 ) .
n , number of patients % , percentage of patients not all patients with hearing loss had complaints related to hearing .
we analyzed the 378 ( 96.18% ) charts of children with no complaints about hearing and considered the presence or absence and the type of hearing loss in the audiologic assessment ( table 4 ) .
we did not find a significant association ( p = 0.83 ) between the presence of hearing complaints and hearing loss in all the patients ( n = 393 ) . considering each ear ( right and left ) of all the 393 patients ( n = 786 ) ,
the otoscopy findings were normal in 755 ears ( 96.06% ) and abnormal in only 31(3.94% ) .
hearing disorders in children should be identified and treated early , because even mild hearing loss can influence the way sounds are processed and affect language development ; consequences include speech production with phonetic errors , learning difficulties , poor reading comprehension , and unsatisfactory academic performance , as well as inadequate social skills7
8 .
it is noteworthy that hearing impairment in children with cleft lip and palate is a secondary feature , and for this reason , hearing complaints are often not reported by parents . however , in cases of mild hearing loss , symptoms may go unnoticed by the individual and/or family9 , or the individual may present asymptomatic auditory alterations , which highlights the importance of early audiologic diagnosis to enable appropriate treatment . in a study conducted at the speech language pathology and audiology department of the baleia hospital in belo horizonte
, 85% of the children aged between 3 and 12 years with surgically repaired cleft palate did not present auditory complaints10 .
this is corroborated by the data obtained in this study , in which 96% had no auditory complaints . regarding the types of auditory complaint ,
a study11 conducted with 150 medical records showed that 83% of the sample had some type of hearing complaint , the most frequent being unilateral or bilateral hearing loss ( 64% ) .
otitis and otorrhea ( current or previous ) were more prevalent in the presurgical groups undergoing tympanoplasty and tympanomastoidectomy .
the least reported complaint was otalgia , which was present in only 37% of the sample .
because serous otitis media does not cause pain , it is a silent pathology , going unnoticed by the individual or family12 .
however , the literature is generally limited to the presence or absence of hearing complaints and does not note the type of complaint most commonly found in individuals with cleft lip and palate9 . in this study ,
the main complaints reported by parents of children with hearing complaints were related to the conductive system , because the most frequent complaints reported in the audiologic interview were otitis and otorrhea .
we observed that even in cases where there was no complaint of hearing loss or hearing difficulties , hearing loss was detected . from the analysis of the 378 records of children with no history of auditory complaints , 108 ( 28.57% ) had some type of hearing loss in the audiologic assessment , the majority ( 94% ) being conductive hearing loss in at least one ear .
hearing loss is unnoticeable until its effects translate into oral language impairment , and rehabilitation at this stage may be less effective .
thus , early detection of this disorder is critical13 . parents may fail to identify hearing loss because the presence of otitis media with effusion ( ome ) in children is usually inconspicuous and does not cause pain14 . depending on age , complaints may not be specific and include fever , irritability , moderate or intense crying , anorexia , diarrhea , and vomiting15 . considering that our study sample represents school - aged children , recognition of hearing difficulties and early diagnosis of the severity of the hearing loss , together with preventative actions for consequences related to auditory and communication skills , are important factors in the academic development of a student with hearing loss16 .
another study that sought to determine the frequency of hearing complaints in children with learning difficulties pointed out that complaints of tinnitus and discomfort to sounds were the most frequent in this group17 .
our study found complaints of tinnitus in 33.33% of the children with hearing complaints , which might suggest , in addition to possible hearing alterations , other impairments of metabolic or circulatory origin .
we consider the low presence of alterations on otoscopy ( 3.94% ) due to use of conventional otoscopy .
studies18
19 support the use of pneumatic otoscopy as a diagnostic tool , which is suitable , inexpensive , and can predict the presence of fluid ( effusion ) in the middle ear .
the position and mobility of the eardrum are considered the most important diagnostic indicators . the results of this study suggest the use of questionnaires and checklists , with greater specificity and sensitivity for otologic and auditory problems , in the population with cleft lip and palate .
parents require fundamental guidelines so they can recognize even mild hearing difficulties in their children and , therefore , minimize the disorders that may arise as a result of sensory deprivation .
the present study showed no association between the auditory complaints and the conventional audiologic assessment . | summary
introduction : at the initial consultation , the speech language pathologist and audiologist may consider possible diagnostic hypotheses based on the child 's history and the parents ' complaint .
aim : to investigate the association of hearing complaints with the findings obtained in the conventional audiologic assessment in children with cleft lip and palate .
retrospective study .
methods : we analyzed medical charts of 1000 patients with cleft lip and palate who underwent surgical repair between 1988 and 1995 at a mean age of 6 years 8 months .
we excluded charts with records of inconsistent audiological responses and charts with missing data for any of the audiologic evaluations considered .
thus , the sample consisted of 393 records .
results : two hundred thirty - nine patients presented hearing loss in one or both ears , but only 3.8% reported hearing complaints . the most frequent were otorrhea followed by otalgia . there was no statistical significance between the complaint and gender ( p = 0.26 ) nor between the complaint and hearing loss ( p = 0.83 ) .
conclusion : this study showed no association between the hearing complaint and the conventional audiologic assessment . |
throughout the paper @xmath0 is a simply - connected simple compact lie group and @xmath1 is an orientable smooth closed 4-manifold . given a principal @xmath0-bundle @xmath6 , its associated gauge group @xmath7 is the group of @xmath0-equivariant automorphisms of @xmath8 which fix @xmath1 and the pointed gauge group @xmath9 is the subgroup containing those automorphisms which restrict to the identity on the fiber over the basepoint . in @xcite , atiyah and bott show that @xmath10 is weakly homotopy equivalent to @xmath11 , the component of the space of maps from @xmath1 to @xmath12 that contains the map inducing @xmath8 .
similarly there is a weak homotopy equivalence between @xmath13 and the pointed mapping space @xmath14 . in what follows we do not distinguish between @xmath10 and @xmath11 .
the isomorphism class of @xmath8 is classified by @xmath15 $ ] . in the cases we consider
@xmath15 $ ] is isomorphic to @xmath16 and each principal @xmath0-bundle @xmath8 corresponds to some integer @xmath17 .
denote its associated gauge group by @xmath18 .
in @xcite theriault shows that when @xmath1 is a simply - connected spin 4-manifold with @xmath19 of rank @xmath20 there is a homotopy equivalence @xmath21 this reduces the calculation of the homotopy type of @xmath18 to that of @xmath22 . in the non - spin case the homotopy equivalence still holds when localized away from 2 .
the goal of this paper is to study the homotopy types of @xmath18 for non - simply - connected @xmath1 .
it turns out that under certain conditions the structure of @xmath23 determines a decomposition of @xmath18 . in section 2
we develop lemmas which lead to a statement relating a splitting of @xmath23 to a decomposition of @xmath18 .
more precisely , if there is a homotopy equivalence @xmath24 such that @xmath25 and the @xmath26 s are cw - complexes satisfying the conditions described in proposition [ x seq ] , then @xmath18 will admit a homotopy decomposition @xmath27 where @xmath28 is the connected component containing the basepoint . in section 3
we apply this result and calculate @xmath23 and @xmath18 for three specific cases of non - simply - connected 4-manifolds @xmath1 , in which the @xmath26 s are spheres and moore spaces , and @xmath25 is either @xmath29 or @xmath30 according to the structure of @xmath23 .
in this section we develop some useful lemmas that apply more generally to an orientable 4-dimensional cw - complex @xmath31 with one 4-cell . for @xmath32 let @xmath33 be its @xmath34-skeleton and
let be the attaching map of the 4-cell .
we begin by showing that the isomorphism class of principal @xmath0-bundles over @xmath31 is classified by @xmath16 .
[ isom class of p_k ] there is an isomorphism @xmath35\cong{\mathbb{z}}$ ] .
the homotopy cofibration sequences @xmath36 give the following diagram @xmath37}\ar[d]^-{(\sigma q)^ * } & & & \\ { [ \sigma(x_3 ) , bg]}\ar[r]^-{(\sigma f)^*}\ar[d ] & { [ s^4 , bg]}\ar[r]^-{p^ * } & { [ x , bg]}\ar[r ] & { [ x_3 , bg]}\\ { [ \sigma(x_2 ) , bg ] } & & & } \ ] ] where the row and the column are exact sequences .
we will show that @xmath38 is an isomorphism .
since @xmath12 is 3-connected , @xmath39 $ ] and @xmath40 $ ] are zero .
therefore @xmath38 is an epimorphism and any map @xmath41 $ ] has a lifting @xmath42 through @xmath43 to @xmath44 $ ] .
the latter implies that @xmath45 .
note that the composition @xmath46 is the differential map of the 4-cell in the cellular chain complex of @xmath31 .
since @xmath47 is @xmath16 , this implies that @xmath46 is null homotopic .
therefore @xmath48 and so @xmath49 .
hence @xmath38 is also an injection .
lemma [ isom class of p_k ] says that any principal @xmath0-bundle over @xmath31 corresponds to some integer @xmath17 so our notation @xmath50 is justified .
when @xmath31 is simply - connected , it admits a minimal cell structure so @xmath51 is homotopy equivalent to a wedge of 2-spheres @xmath52 .
the homotopy equivalence in ( [ simply_conn_decomp ] ) is obtained as a consequence of the attaching map @xmath53 of the 4-cell in @xmath31 having the property that @xmath54 is null homotopic .
so if we can find a subcomplex @xmath55 such that the attachment of @xmath53 onto @xmath56 vanishes after suspension , then @xmath50 can be decomposed into a mapping space of @xmath56 and other factors following the same argument .
[ suspended f as sum ] if @xmath57 , then @xmath54 is homotopic to where @xmath58 is the composition @xmath59 .
since @xmath54 is a co - h - map , there is a homotopy commutative diagram @xmath60 ^ -{\sigma f}\ar[d]^-{\sigma } & \sigma(x_3)\ar[r]^-{g+h}\ar[d]^-{\sigma } & \sigma(x_3)\\ s^4\vee s^4\ar[r]^-{\sigma f\vee\sigma f } & \sigma(x_3)\vee\sigma(x_3)\ar[r]^-{g\vee h } & \sigma(x_3)\ar[u]_-{\triangledown } } \ ] ] where @xmath61 is the comultiplication and @xmath62 is the folding map .
the map along the bottom row is homotopic to @xmath63 , so we have @xmath64 .
go back to our case .
observe that @xmath65 is the identity map in @xmath66 .
therefore we have @xmath67 . [ gaugedecomp ]
suppose that there exist a cw - complex @xmath56 of dimension at most 3 and a map @xmath68 such that @xmath69 has a left homotopy inverse .
then @xmath70 , where @xmath71 is the homotopy cofibre of @xmath72 , and there is a homotopy equivalence @xmath73 where @xmath28 is the connected component containing the basepoint .
the homotopy cofibration sequence @xmath74 induces a long exact sequence @xmath75\overset{(\sigma\phi)^*}{\longrightarrow}[\sigma y , bg]\overset{\epsilon^*}{\longrightarrow}[x ' , bg]\overset{q^*}{\longrightarrow}[x , bg]\overset{\phi^*}{\longrightarrow}[y , bg].\ ] ] since @xmath69 has a left homotopy inverse , the map @xmath76 is null homotopic and @xmath77 is zero . by hypothesis ,
the dimension of @xmath56 is at most 3 and @xmath12 is 3-connected , so @xmath78 $ ] is zero .
therefore by exactness @xmath79\to[x , bg]$ ] is an isomorphism .
fix an integer @xmath17 and consider evaluation fibrations @xmath80 { \textrm{map}}^*_k(x ' , bg)\rightarrow{\textrm{map}}_k(x ' , bg)\rightarrow bg .
& \end{array}\ ] ] since @xmath81 is an isomorphism , by naturality there is commutative diagram @xmath82\ar@{=}[d ] & { \textrm{map}}^*_k(x ' , bg)\ar[r]\ar[d]^-{q^ * } & { \textrm{map}}_k(x ' , bg)\ar[r]\ar[d]^-{q^ * } & bg\ar@{=}[d]\\ g\ar[r ] & { \textrm{map}}^*_k(x , bg)\ar[r ] & { \textrm{map}}_k(x , bg)\ar[r ] & bg } \]][1-conn naturality ] as in @xcite , from the left square in ( [ 1-conn naturality ] ) we obtain a homotopy commutative diagram @xmath83 ^ -{\cong}\ar[d ] & { \textrm{map}}^*_k(\sigma x , bg)\ar[d]\\ { \mathcal{g}}_k(x')\ar[r]^-{q^*}\ar@{=}[d ] & { \mathcal{g}}_k(x)\ar[r]^-{h}\ar[d ] & { \textrm{map}}^*_{k'}(\sigma y , bg)\ar[d]^-{\epsilon^*}\\ { \mathcal{g}}_k(x')\ar[r ] & g\ar[r]\ar[d ] & { \textrm{map}}^*_k(x ' , bg)\ar[d]\\ & { \textrm{map}}^*_k(x , bg)\ar@{=}[r ] & { \textrm{map}}^*_k(x , bg ) } \ ] ] here @xmath84 is some connected component .
it is known that all connected components of @xmath85 are homotopy equivalent as @xmath86 is a co - h - space @xcite , so we may replace it by @xmath87 . since @xmath76 is null homotopic , @xmath77 is trivial and therefore @xmath88 has a right homotopy inverse .
the group multiplication in @xmath50 then gives a homotopy equivalence @xmath89 and therefore @xmath50 is homotopy equivalent to @xmath90 . by cellular approximation
, we may assume that the image of @xmath72 is contained in @xmath51 .
let @xmath91 be the map induced by restricting the range of @xmath72 to @xmath51 . if @xmath69 has a left homotopy inverse @xmath92 , then the composition @xmath93 is a left homotopy inverse of @xmath94 .
therefore @xmath66 is homotopy equivalent to @xmath95 , where @xmath96 is the homotopy cofibre of @xmath97 , and the composition @xmath98 is null homotopic .
conversely , the latter two conditions imply that @xmath69 has a left homotopy inverse
. then we can rephrase lemma [ gaugedecomp ] as follows .
[ gaugedecomp][sigma f factors ] suppose that there exist a cw - complex @xmath56 of dimension at most 3 and a map @xmath91 such that : ( 1 ) @xmath99 and ( 2 ) the composition @xmath100 is null homotopic .
then there are homotopy equivalences @xmath101 moreover , @xmath54 factors through @xmath102 where @xmath103 is the attaching map of the 4-cell in @xmath71 . from the above discussion , we only need to show that @xmath54 factors through @xmath102 .
expand the commutative diagram @xmath104\ar[d]^-{\phi ' } & y\ar[d]^-{\phi}\\ x_3\ar[r ] & x } \ ] ] to a homotopy cofibration diagram @xmath104\ar[d]^-{\phi ' } & y\ar[r]\ar[d]^-{\phi } & { * } \ar[r]\ar[d ] & \sigma y\ar[d]^-{\sigma\phi'}\\ x_3\ar[r]\ar[d]^-{q ' } & x\ar[r]\ar[d]^-{q } & s^4\ar[r]^-{\sigma f}\ar@{=}[d ] & \sigma(x_3)\ar[d]^-{\sigma q'}\\ x'_3\ar[r ] & x'\ar[r ] & s^4\ar[r]^-{\sigma f ' } & \sigma(x'_3 ) } \ ] ] which defines the maps @xmath105 and @xmath106 .
let be a left homotopy inverse of @xmath69 and let @xmath107 be the suspension of the skeletal inclusion .
by lemma [ suspended f as sum ] we have @xmath108 since @xmath109 is null homotopic , @xmath110 factors through @xmath102 .
[ q isom on h free ] assume the conditions in proposition [ gaugedecomp ] .
if @xmath111 is torsion , then the quotient map @xmath112 induces an isomorphism @xmath113 preserving cup products on the free parts .
consider the long exact sequence of reduced cohomology groups @xmath114 again , use a left homotopy inverse and get an isomorphism @xmath115 since @xmath111 is torsion , @xmath81 is an isomorphism on the free part of second cohomology groups and the naturality of cup products implies the statement .
now we go back to calculate @xmath50 when @xmath31 is simply - connected .
the 3-skeleton @xmath51 is homotopy equivalent to @xmath116 and the attaching map @xmath53 is an element of @xmath117 . by the hilton - milnor theorem
it can be written as @xmath118 , where @xmath119 is an integer , the map @xmath120 is the composition of the hopf map @xmath121 with the inclusion and @xmath122 is a sum of whitehead products .
if @xmath54 is not trivial , then some of the @xmath119 s are odd .
let @xmath123 be the number of odd @xmath119 s , where @xmath124 .
relabelling the spheres if necessary , we may assume that @xmath119 is odd for @xmath125 and is even otherwise .
we can imagine that @xmath53 is a vector , @xmath119 s are coordinates and the pinch map @xmath126 is a coordinate function because @xmath58 kills @xmath122 and @xmath127
. in linear algebra , the expression of a vector can be simplified by change of basis .
the following lemma realizes this idea geometrically .
suppose that @xmath128 is a wedge of 2-spheres and @xmath118 .
then there is a map @xmath129 such that its homotopy cofibre @xmath130 is homotopy equivalent to @xmath31 and it satisfies @xmath131 and @xmath132 , where @xmath133 and @xmath134 .
if all @xmath119 s are even , then @xmath54 is zero in @xmath135 and set @xmath136 to be @xmath53 .
otherwise @xmath123 , the number of odd @xmath119 s , is greater than zero . for each @xmath137 , define a map @xmath138 as follows .
on @xmath139 , @xmath140 is the composition @xmath141 where @xmath61 is a comultiplication and @xmath62 is a folding map of @xmath142 and @xmath143 . on the remaining spheres , @xmath140 is the identity .
extend @xmath140 to the whole of @xmath31 and call it @xmath144 . since @xmath144 induces an isomorphism on @xmath145 and @xmath31
is simply - connected , @xmath144 is a homotopy equivalence .
let @xmath146 be @xmath147 and @xmath148 be its homotopy cofibre .
then there is a homotopy commutative diagram @xmath149 ^ -{f}\ar@{=}[d ] & x_3\ar[r]\ar[d]^-{\phi_k } & x\ar[d]^-{\tilde{\phi_k}}\\ s^3\ar[r]^-{\tilde{f}_k } & x_3\ar[r ] & \tilde{x}_k } \ ] ] by the five lemma , @xmath150 is an isomorphism on their cohomology groups , so by whitehead s theorem @xmath150 is a homotopy equivalence .
further , @xmath151 where @xmath152 and @xmath153 .
the composition @xmath154 is homotopic to @xmath155 because is homotopic to @xmath156 and @xmath157 .
set @xmath136 to be @xmath158 and set @xmath130 to be its homotopy cofibre .
then @xmath136 and @xmath130 satisfy the statement requirements .
if @xmath54 is trivial , then the 5-cell attaches to @xmath66 at the basepoint and @xmath159 is homotopy equivalent to @xmath160 .
set @xmath56 to be @xmath52 and set @xmath161 to be the identity .
then lemma [ gaugedecomp ] recovers equation ( [ simply_conn_decomp ] ) , @xmath162 if @xmath54 is not trivial , then we may replace @xmath31 by @xmath130 and @xmath53 by @xmath136 in lemma [ simplify s2 ] such that @xmath163 .
the 5-cell only attaches to @xmath164 in @xmath66 .
set @xmath56 to be @xmath165 and set @xmath166 to be the inclusion .
the quotient @xmath167 is the mapping cone of @xmath168 where @xmath169 is odd .
denote it by @xmath170 .
we adopt this notation because @xmath170 is @xmath30 when @xmath171 or @xmath172 .
one may ask when @xmath173 can be replaced by @xmath174 .
[ cp_a ] for @xmath169 odd , @xmath175 is homotopy equivalent to @xmath176 .
let @xmath177 be the composition @xmath178 and let @xmath179 be its homotopy cofibre .
by lemma [ simplify s2 ] , we can assume that @xmath180 is @xmath181 and the composition is null homotopic . set @xmath56 to be @xmath182 and use lemma [ gaugedecomp ] to get @xmath183 swap @xmath184 and @xmath182 and repeat the process .
then we have @xmath185 comparing the two equations gives the asserted homotopy equivalence .
[ simplify s2 ] assume that @xmath51 is homotopy equivalent to @xmath116 and @xmath145 satisfies poincar duality . if @xmath54 is null homotopic , then there are homotopy equivalences @xmath186 and if @xmath54 is non - trivial , then there are homotopy equivalences @xmath187 the case when @xmath54 is trivial is already discussed above .
assume that @xmath54 is not trivial .
if @xmath51 is @xmath188 , then poincar duality will imply that the cup square product of the generator of @xmath189 must be 1 or -1 .
therefore @xmath31 is homotopy equivalent to @xmath30 and the statement holds . otherwise , write @xmath118 where @xmath190 and @xmath122 is a sum of whitehead products .
at least one of the @xmath119 s is odd and it may be assumed to be @xmath191 without loss of generality . by lemma
[ simplify s2 ] we may assume @xmath192 .
since the 5-cell only attaches to @xmath164 , @xmath159 is homotopy equivalent to @xmath193 .
set @xmath194 to be the wedge of 2-spheres except @xmath184 .
then the composition @xmath195 is null - homotopic and lemma [ gaugedecomp ] implies that there is a homotopy equivalence @xmath196 since @xmath20 is great than 1 , there is at least one copy of @xmath197 in the equation .
therefore we can replace @xmath198 by @xmath174 by lemma [ cp_a ] .
lemma [ simplify s2 ] is a refinement of equation ( [ simply_conn_decomp ] ) for the non - spin case in @xcite .
it uses lemma [ cp_a ] which says that for @xmath169 odd , @xmath173 is homotopy equivalent to @xmath174 in the presence of @xmath197 .
in fact after localizing away from 2 , the attaching maps in @xmath30 and @xmath170 are trivial , so @xmath174 and @xmath173 are both homotopy equivalent to @xmath199 and hence homotopy equivalent to each other . moreover , since @xmath200 is homotopic to @xmath201
, there is a homotopy equivalence .
the evaluation fibrations @xmath202
\omega{\textrm{map}}_k(\sigma{\mathbb{c}}{\mathbb{p}}^2_a)\to\omega g\to{\textrm{map}}^*_k(\sigma{\mathbb{c}}{\mathbb{p}}^2_a)\to{\textrm{map}}_k(\sigma{\mathbb{c}}{\mathbb{p}}^2_a)\to g & \end{array}\ ] ] and the naturality of @xmath203 give a homotopy commutative diagram @xmath204\ar[r ] & \omega g\ar@{=}[d]\ar[r ] & { \textrm{map}}_k^*(\sigma{\mathbb{c}}{\mathbb{p}}^2_a , bg)\ar[d]^-{\varphi^*}\\ \omega{\mathcal{g}}_k({\mathbb{c}}{\mathbb{p}}^2)\ar[r ] & \omega g\ar[r ] & { \textrm{map}}_k^*(\sigma{\mathbb{c}}{\mathbb{p}}^2 , bg ) . }
\ ] ] so @xmath205 and @xmath206 are homotopy equivalent .
all these facts suggest that @xmath174 and @xmath173 may be homotopy equivalent , but we can not determine the answer exactly . we summarizing this section in the following proposition .
[ x seq ] suppose that @xmath31 is an orientable 4-dimensional cw - complex with one 4-cell .
let @xmath207 be a sequence of cw - complexes such that ( 1 ) @xmath208 and ( 2 ) for , where @xmath209 and @xmath26 is a cw - complex of dimension at most 3 .
if for each triple @xmath210 satisfies the conditions in lemma [ gaugedecomp ] , then there are homotopy equivalences @xmath211 in addition , if ( 3 ) all @xmath212 s are torsion , ( 4 ) the 3-skeleton of @xmath71 is homotopy equivalent to @xmath52 and ( 5 ) @xmath145 satisfies poincar duality , then we have @xmath213 when @xmath54 is null homotopic and @xmath214 when @xmath54 is non - trivial .
the first two homotopy equivalences clearly come from applying lemma [ gaugedecomp ] to each triple @xmath210 .
so we only need to prove the second part .
suppose that the sequence satisfies conditions ( 3 ) ( 5 ) .
let @xmath215 be the attaching maps of the 4-cell in @xmath216 and let @xmath217 be the quotient map .
since all the @xmath212 s are torsion , the composition @xmath218 induces an isomorphism which preserves cup products on the free part by lemma [ q isom on h free ] and hence @xmath219 satisfies poincar duality .
moreover , each @xmath220 factors through @xmath221 by lemma [ sigma f factors ] , so @xmath222 is trivial if and only if @xmath54 is .
applying lemma [ simplify s2 ] to @xmath25 implies the statement .
from now on we assume that @xmath1 is an orientable smooth closed 4 manifold . using morse theory , in ( * ? ? ?
* theorem 3.35 ) it is shown that @xmath1 admits a cw - structure with one 4-cell .
let @xmath223 be the 3-skeleton of @xmath1 and let @xmath224 be the attaching map of the 4-cell . in this section we will calculate the homotopy types of @xmath23 and @xmath18 when @xmath2 is : ( 1 ) a free group @xmath3 ; ( 2 ) a cyclic group @xmath4 where @xmath5 is an odd prime ; ( 3 ) a free product of the previous two types @xmath225 , where @xmath226 is a power of an odd prime .
when @xmath2 is a free group , there is a homotopy equivalence @xcite @xmath228 for @xmath229 , let @xmath230 be the @xmath34th copy of the @xmath123-sphere and let @xmath231 be the composition . by lemma [ suspended f as sum ] ,
@xmath54 is homotopic to the sum @xmath232 . for each @xmath233 ,
the map @xmath234 is null homotopic because @xmath235 is zero .
note that @xmath236 is the differential map of the 4-cell to @xmath237 in the cellular chain complex .
it is zero since @xmath1 is orientable and @xmath238 .
therefore each @xmath239 is null homotopic for @xmath240 and @xmath241 .
set @xmath31 to be @xmath1 , set @xmath56 to be @xmath242 and set @xmath243 to be the inclusion .
then the composition @xmath244 is null homotopic .
note that @xmath111 is zero and @xmath245 is @xmath246 .
using proposition [ x seq ] we have the following theorem .
[ gauge decomp_free ] suppose @xmath247 .
if @xmath54 is null homotopic , then there are homotopy equivalences @xmath248 \displaystyle{{\mathcal{g}}_k(m)\simeq{\mathcal{g}}_k(s^4)\times\prod^m_{i=1}\omega^3_0g\times\prod^d_{j=1}\omega^2g\times\prod^m_{k=1}\omega g. } \end{array}\ ] ] if @xmath54 is non - trivial , then there are homotopy equivalences @xmath249 \displaystyle{{\mathcal{g}}_k(m)\simeq{\mathcal{g}}_k({\mathbb{c}}{\mathbb{p}}^2)\times\prod^m_{i=1}\omega^3_0g\times\prod^{d-1}_{j=1}\omega^2g\times\prod^m_{k=1}\omega g. } \end{array}\ ] ] for @xmath251 , recall that an @xmath252-dimensional moore space @xmath253 is defined to be the mapping cone of the degree @xmath17 map .
its reduced homology groups are zero except .
denote its generator by @xmath254 . with @xmath255 coefficients
, the universal coefficient theorem implies that @xmath256 is generated by @xmath254 , @xmath257 is generated by @xmath258 , the bockstein homomorphism image of @xmath254 , and @xmath259 is zero for @xmath260 . for any space @xmath31 , define the mod-@xmath17 homotopy group @xmath261 to be @xmath262 $ ] .
the comultiplication of @xmath253 induces a group multiplication in @xmath261 for @xmath263 , which becomes abelian for @xmath264 since @xmath265 .
moreover , there is a mod-@xmath17 hurewicz homomorphism analogous to the integral hurewicz homomorphism @xmath266 it is natural and compatible with bockstein homomorphisms @xcite @xmath267 & \pi_{n+1}(x;{\mathbb{z}}_k)\ar[r]^-{\beta_\pi}\ar[d]^-{\bar{\varphi } } & \pi_n(x)\ar[r]^-{k}\ar[d]^-{\varphi } & \pi_n(x)\ar[r]\ar[d]^-{\varphi } & \pi_n(x;{\mathbb{z}}_k)\ar[r]\ar[d]^-{\bar{\varphi } } & \cdots\\ \cdots\ar[r ] & h_{n+1}(x;{\mathbb{z}}_k)\ar[r]^-{\beta } & h_n(x)\ar[r]^-{k } & h_n(x)\ar[r ] & h_n(x;{\mathbb{z}}_k)\ar[r ] & \cdots } \ ] ] where @xmath268 is the standard hurewicz homomorphism and @xmath269 is the bockstein homomorphism on homotopy groups . let @xmath270 be the kernel of @xmath268 .
the mod-@xmath17 hopf invariant is defined in a similar way to the integral hopf invariant . for
a map @xmath271 , let @xmath272 be the mapping cone of @xmath273 , and let @xmath123 and @xmath274 be generators of @xmath275 and @xmath276 .
then the mod-@xmath17 hopf invariant @xmath277 is defined by the formula @xmath278 .
* corollary 11.12)[mod p hurewicz ses ] let @xmath263 and @xmath5 be an odd prime .
then there is a short exact sequence @xmath279 where @xmath280 and @xmath281 for @xmath264 .
moreover , if @xmath282 , then it is null homotopic if and only if its mod-@xmath283 hopf invariant @xmath284 .
suppose that @xmath2 is @xmath4 .
poincar duality and the universal coefficient theorem imply that @xmath1 has homology groups @xmath285 in order to apply proposition [ x seq ] to calculate @xmath18 , we need to study the structure of @xmath286 . after localizing away from @xmath5 ,
any @xmath289 is contractible so @xmath287 and @xmath288 are @xmath5-torsion .
localize at @xmath5 .
consider the long exact sequence of homotopy groups for the pair @xmath290 @xmath291 the pair @xmath290 is 3-connected , so @xmath292 is @xmath16 by the hurewicz theorem .
since @xmath293 at odd primes , @xmath294 is an injection .
but @xmath287 is torsion , so this injection only makes sense if @xmath295 .
now we calculate @xmath288 .
it is equal to @xmath296 , where @xmath297 is the homotopy fibre of the pinch map @xmath298 . by (
* proposition 11.7.1 ) , there is a @xmath5-local homotopy equivalence @xmath299 where @xmath300 is the fibre of the degree @xmath301 map @xmath302 and the dimension @xmath303 is either 3 or higher than 4 . on the right side , @xmath304 and @xmath305 since @xmath306 is 3-connected for each @xmath307 . for the remaining factor of @xmath308 , consider the string of isomorphisms @xmath309 the first isomorphism is obtained from the hilton - milnor theorem using dimension and connectivity considerations .
the second isomorphism holds since only one @xmath310 equals 3 while the rest are strictly larger than 4 .
the third isomorphism holds by adjunction , and the isomorphism with zero holds by the first assertion of the lemma .
therefore @xmath311 and hence so is @xmath288 .
[ 2 moore sp p ] if @xmath2 is @xmath4 for @xmath5 an odd prime , then there is a homotopy equivalence @xmath312 in addition , there exists a map @xmath313 such that @xmath314 is an isomorphism and @xmath315 has a left homotopy inverse .
after suspension , @xmath286 is simply - connected and admits a minimal cell structure . by ( * ? ? ?
* proposition 4h.3 ) @xmath286 is homotopy equivalent to the mapping cone of @xmath316 where @xmath88 induces a trivial homomorphism @xmath317 .
now we claim that @xmath88 is null homotopic . since @xmath318\cong[p^3(p^r ) , p^3(p^r)]\oplus(\oplus^d_{i=1}[s^2_i , p^3(p^r)]),\ ] ] we may write @xmath319 , where @xmath320 $ ] and @xmath321 $ ] . consider the commutative diagram @xmath322 & k_3(p^r)\ar[r ] & \pi_3(p^3(p^r);{\mathbb{z}}_{p^r})\ar[r]^-{\varphi}\ar[d]^-{\beta_\pi } & h_3(p^3(p^r);{\mathbb{z}}_{p^r})\ar[r]\ar[d]^-{\beta_h } & 0\\ & & \pi_2(p^3(p^r))\ar[r]^-{\varphi } & h_2(p^3(p^r ) ) & } \ ] ] where the first row is the exact sequence in lemma [ mod p hurewicz ses ] and the square is due to the compatibility of mod-@xmath283 hurewicz homomorphisms and bockstein homomorphisms . since @xmath323 is trivial , so is @xmath324 and therefore @xmath325 .
note that @xmath326 is an isomorphism in this case , so @xmath327 is in the kernel @xmath328 .
denote the mapping cone of @xmath327 by @xmath329 .
since @xmath330 is a suspension , @xmath331 has trivial cup products and so does @xmath332 .
therefore the mod-@xmath283 hopf invariant @xmath333 is zero and @xmath327 is null homotopic by lemma [ mod p hurewicz ses ] . for each @xmath34 , there is a commutative diagram @xmath334 ^ -{[\,h''_i]\,}\ar[d]_-{\varphi } & \pi_2(p^3(p^r))\ar[d]_-{\varphi}\\ h_2(s^2_i)\ar[r]^-{(h''_i ) _ * } & h_2(p^3(p^r ) ) } \ ] ] both hurewicz homomorphisms @xmath268 are isomorphisms by the hurewicz theorems .
the induced homomorphism @xmath335 is trivial and the diagram implies that @xmath336 is null homotopic .
now we prove the second part of the lemma .
the 1-skeleton of @xmath1 is a wedge of spheres @xmath337 .
let @xmath338 and @xmath339 be inclusions .
their induced homomorphisms @xmath340 is a surjection and @xmath341 is a reduction map .
therefore at least one of the @xmath342 s sends the identity @xmath343 to the generator of @xmath2 . without loss of generality
we assume that it is @xmath344 .
extend @xmath345 to @xmath346 through the pinch map @xmath274 .
@xmath347 ^ -{p^r } & s^1\ar[r]^-{\beta}\ar[d]^-{j_1 } & p^2(p^r)\ar@{-->}[dl]^{\epsilon}\\ & m & } \ ] ] by cellular approximation the range of @xmath76 can be restricted to @xmath223 .
note that both @xmath348 are reduction maps and @xmath349 , so @xmath314 is an isomorphism . by the hurewicz theorem ,
the induced homology group homomorphism is an isomorphism and so is @xmath350 .
therefore the composition @xmath351 induces an isomorphism in homology and so is a homotopy equivalence .
[ gauge decomp_torsion ] suppose that @xmath2 is @xmath4 where @xmath5 is an odd prime .
if @xmath54 is null homotopic , then there are homotopy equivalences @xmath356 \displaystyle{{\mathcal{g}}_k(m)\simeq{\mathcal{g}}_k(s^4)\times\omega^3_0g\{p^r\}\times\prod^d_{i=1}\omega^2g\times\omega^2g\{p^r\}. } \end{array}\ ] ] if @xmath54 is non - trivial , then there are homotopy equivalences @xmath357 \displaystyle{{\mathcal{g}}_k(m)\simeq{\mathcal{g}}_k({\mathbb{c}}{\mathbb{p}}^2)\times\omega^3_0g\{p^r\}\times\prod^{d-1}_{i=1}\omega^2g\times\omega^2g\{p^r\ } , } \end{array}\ ] ] where @xmath358 is the connected component containing the basepoint . in the following
we construct a sequence @xmath207 of cw - complexes satisfying the conditions in proposition [ x seq ] for @xmath1 .
let @xmath359 be the 3-skeleton in @xmath216 and let @xmath215 be the attaching map of the 4-cell .
_ step 1 _ : by lemma [ 2 moore sp p ] , there is a map @xmath313 such that @xmath360 has a left homotopy inverse and @xmath314 is an isomorphism .
set @xmath361 to be @xmath1 , set @xmath362 to be @xmath346 and set @xmath363 to be @xmath76 .
then the composition @xmath364 is null homotopic since @xmath365 by lemma [ pi_pm ] .
then we use lemma [ gaugedecomp ] and get @xmath366 _ step 2 _ : set @xmath367 to be @xmath368 .
then @xmath367 is simply connected and admits a minimal cell structure , that is @xmath369 and @xmath370 .
set @xmath371 to be @xmath372 and set to be the inclusion .
the composition @xmath373 is null homotopic since @xmath287 is zero by lemma [ pi_pm ] .
then we use lemma [ gaugedecomp ] and get @xmath374 _ step 3 _ : set @xmath375 to be @xmath376 .
the 3-skeleton @xmath377 is homotopy equivalent to @xmath378 .
note that @xmath212 is torsion for @xmath379
. then proposition [ x seq ] implies the asserted statement .
suppose that @xmath381 , where @xmath382 is a power of an odd prime .
it is known that for some number @xmath383 there is a diffeomorphism @xmath384 where @xmath385 and @xmath386 s are orientable smooth closed 4-manifolds with @xmath387 and ( * ? ? ? * theorem 1.3 ) .
using the fact that the 3-skeleton of a connected sum @xmath388 is a wedge of the 3-skeletons of @xmath389 and @xmath390 , we can calculate the suspensions and gauge groups for both sides of ( [ klt decomp ] ) . by induction
we only need to show the lemma for @xmath392 .
the 3-skeleton of is @xmath393 .
there is a map @xmath394 which collapses the connecting cylinder between @xmath1 and @xmath395 .
so we have a homotopy commutative diagram @xmath396\ar@{=}[r ] & m_3\vee s^2\vee s^2\ar[d]\\ m\#(s^2\times s^2)\ar[d]\ar[r]^-{q } & m\vee(s^2\times s^2)\ar[d]\\ s^4\ar[d]^-{\sigma f_\#}\ar[r]^-{\sigma } & s^4\vee s^4\ar[d]^-{\sigma f\vee\sigma f_s}\\ \sigma(m_3)\vee s^3\vee
s^3\ar@{=}[r ] & \sigma(m_3)\vee s^3\vee s^3 } \ ] ] where @xmath397 and @xmath398 are the attaching maps in @xmath399 and @xmath395 respectively . set @xmath56 to be @xmath400 and set @xmath401 to be the inclusion .
since @xmath398 is a whitehead product , the composition @xmath402 is null homotopic and the statement follows from lemma [ gaugedecomp ] . [ gauge decomp _ * ] if @xmath381 where @xmath226 is a power of an odd prime , then there exists an integer @xmath383 such that the suspension of @xmath403 is homotopy equivalent to either @xmath404 \displaystyle{\sigma{\mathbb{c}}{\mathbb{p}}^2\vee(\bigvee^m_{i=1}s^4)\vee(\bigvee^n_{j=1}p^4(q_j))\vee(\bigvee^{d+2l-1}_{k=1}s^3)\vee(\bigvee^n_{j'=1}p^3(q_{j'}))\vee(\bigvee^m_{i'=1}s^2 ) . } & \end{array}\ ] ] in the first case , we have @xmath405 in the second case , we have @xmath406 by ( [ klt decomp ] ) there exists a diffeomorphism @xmath407 so it is equivalent to calculate @xmath408 and @xmath409 . in the following
we construct a sequence @xmath207 of cw - complexes satisfying the conditions in proposition [ x seq ] for @xmath410 .
let @xmath359 be the 3-skeleton of @xmath216 and let @xmath215 be the attaching map of the 4-cell .
_ step 1 _ : set @xmath361 to be @xmath411 .
its 3-skeleton @xmath412 is a wedge sum of the 3-skeletons of @xmath385 and the @xmath386 s . in particular
, the 3-skeleton of @xmath385 is @xmath413 @xcite .
set to be the wedge of 1-spheres and 3-spheres and set to be the inclusion . for each @xmath233 ,
the composition @xmath414 is null homotopic since @xmath235 is zero . and for each @xmath237 , the composition @xmath415 is the differential map of the 4-cell in the cellular chain complex , and so is zero because @xmath416 .
then we use lemma [ gaugedecomp ] and get @xmath417 \displaystyle{{\mathcal{g}}_k(x^1)\simeq{\mathcal{g}}_k(x^1/y^1)\times\prod^m_{i=1}\omega^3_0g\times\prod^m_{i'=1}\omega g. } & \end{array}\ ] ] _ step 2 _ : set @xmath367 to be @xmath418 .
its 3-skeleton @xmath419 is a wedge sum of 2-spheres and the 3-skeletons of the @xmath386 s .
denote the 3-skeleton of @xmath386 by @xmath420 . by lemma [ 2 moore sp p ] , @xmath421 is homotopy equivalent to @xmath422 and there exists a map @xmath423 such that @xmath424 has a left homotopy inverse and @xmath425 is an isomorphism . set @xmath371 to be @xmath426 and set @xmath427 to be the composition @xmath428 for each @xmath429 , the composition @xmath430 is null homotopic since @xmath431 is zero by lemma [ pi_pm ] .
then we use lemma [ gaugedecomp ] and get @xmath432 _ step 3 _ : set @xmath375 to be @xmath376 . by the van kampen theorem @xmath433 is an isomorphism and @xmath375 is simply connected .
therefore it admits a minimal cell structure and @xmath434 .
set @xmath435 to be @xmath436 and set @xmath437 to be the inclusion . for each @xmath429 ,
the composition @xmath438 is null homotopic since @xmath439 is zero by lemma [ pi_pm ] .
then we use lemma [ gaugedecomp ] and get @xmath440 _ step 4 _ : set @xmath441 to be @xmath442 .
its 3-skeleton @xmath443 is homotopy equivalent to @xmath444 .
since @xmath212 is torsion free for @xmath445 , proposition [ x seq ] implies that @xmath446 when @xmath447 is null homotopic and @xmath448 when @xmath447 is non - trivial .
the proofs of theorem [ gauge decomp_free ] and [ gauge decomp_torsion ] are also valid for any orientable 4-dimensional cw - complex with one 4-cell , while theorem [ gauge decomp _ * ] requires the smoothness of @xmath1 for the stable diffeomorphism splitting in @xcite .
one can ask under what condition the stabilizing factor @xmath453 can be cancelled so that the factors @xmath454 can be removed from the equation . if this can be achieved , theorem [ gauge decomp_free ] and [ gauge decomp_torsion ] will be corollaries of theorem [ gauge decomp _ * ] when @xmath1 is smooth
. m. atiyah and r. bott , _ the yang - mills equations over riemann surfaces _ , philosophical transactions of the royal society of london .
series a , mathematical and physical sciences , * 308*(1505 ) , ( 1983 ) , 523 615 .
m. kreck , w. lck and p. teichner , stable prime decompositions of 4-manifolds _ prospects in topology _ edited by f. quinn , annuals of mathematics studies , * 138 * , princeton university press , princeton , ( 1995 ) , 251 269 . | let @xmath0 be a simply - connected simple compact lie group and let @xmath1 be an orientable smooth closed 4-manifold . in this paper
we calculate the homotopy type of the suspension of @xmath1 and the homotopy types of the gauge groups of principal @xmath0-bundles over @xmath1 when @xmath2 is : ( 1 ) a free group @xmath3 , ( 2 ) a cyclic group @xmath4 where @xmath5 is an odd prime , or ( 3 ) a free product of the previous two types .
[ multiblock footnote omitted ] |
Brad buys £700,000 bachelor pad (complete with its own cave) to 'get over split from Angelina'
Brad Pitt has bought himself a bachelor pad to help him deal with his split from Angelina Jolie
Brad Pitt has secretly purchased a bachelor pad to help him sort out his split from Angelina Jolie, it was reported yesterday.
The 46-year-old Ocean's Eleven actor has spent £700,000 on the house, complete with a cave, in the Hollywood Hills.
'The house oozes character,' said a source. 'Brad has had his eye on it for some time but he decided now was the right time to buy because he wanted a place to call his own.
'He needs somewhere quiet that doesn't have memories of Angie and where he can be alone and think about what he does next.'
Built in 1920 and originally on sale for £1.3million, the property has two bedrooms, two bathrooms and a bar area. The cave is built into the foundations.
It was reported yesterday that Pitt's mother Jane has stepped in to try to save his relationship with Miss Jolie.
She plans to use the skills she learnt working as a family counsellor when she meets the 34-year-old actress in Los Angeles next week.
The 70-year-old has apparently become close to Miss Jolie thanks to their joint work in setting up a cancer centre.
She has however always favoured her son's ex-wife, the actress Jennifer Aniston, 40.
Pitt and Miss Jolie are already believed to have enlisted lawyers to negotiate the division of their £205million fortune and custody of their children.
Hideaway: The actor has spent £700,000 on the house, complete with a cave, in the Hollywood Hills
Bachelor pad: The property has two bedrooms, two bathrooms and a bar area - plus a secret cave built into the foundations
But a family source said: 'Brad is desperately trying to cling on to the wreckage of the relationship as he is still very much in love with Angelina and believes they can make it work.
'Jane wants what is best for her son and grandchildren and Angie has agreed to meet her.
'She has stuck at her own marriage and worked with families for 30 years trying to keep them together.'
In happier times: Brad and Angelina at last year's Cannes Film Festival
The couple have six children: adopted sons Maddox, eight, and Pax, six; adopted daughter Zahara, five; and their natural children Shiloh, three, and twins Knox and Vivienne, 17 months.
They got together in 2005 - shortly after Pitt's four-year marriage to Miss Aniston failed. ||||| Richie Sambora and Jon Bon Jovi are going at it as if they Richards and Jagger! Richie's bailing on their tour ... and we know what it's gonna take to put the band back together.Plus, Justin Bieber's so busted up over Selena Gomez that he's taking it out on the world?? That's… | – The latest development in the gossip universe’s breathless coverage of Brad Pitt and Angelina Jolie’s rumored split: Brad bought himself a $1.1 million bachelor pad. This according to the Daily Mail, which even has pictures of the two-bedroom, two-bath place (it comes complete with, literally, a man cave). “'Brad has had his eye on it for some time but he decided now was the right time to buy because he wanted a place to call his own,” a source tells the Mail. "He needs somewhere quiet that doesn't have memories of Angie and where he can be alone and think about what he does next." Another source says Brad is trying to make his relationship work, and his mother is on board to help the couple, and will be meeting the actress next week. Meanwhile, TMZ reports Pitt—and his enormous beard—were spotted at the LA home he shares with Jolie on Sunday. |
A TV host and sports broadcaster on Thursday accused Sen. Al Franken Alan (Al) Stuart FrankenGillibrand announces exploratory committee to run for president on Colbert The Hill’s 12:30 Report: Trump AG pick Barr grilled at hearing | Judge rules against census citizenship question | McConnell blocks second House bill to reopen government Overnight Health Care: House Dems launch major drug pricing investigation | Judge blocks Trump contraception rule rollback | Booker tries to shake doubts about pharmaceutical ties ahead of 2020 | FDA to resume high-risk food inspections MORE (D-Minn.) of kissing and groping her without her consent in 2006.
Leeann Tweeden accused Franken of groping her, without her consent, while she was asleep and provided a photo as evidence.
KABC anchor: Senator Al Franken Kissed and Groped Me Without My Consent, And There’s Nothing Funny About It https://t.co/lG4A1ZTUhC pic.twitter.com/EYIzr9ok2s — Meridith McGraw (@meridithmcgraw) November 16, 2017
The incident happened in December 2006, she said, when she and Franken, then a comedian, were on a USO tour to "entertain our troops."
Franken in a statement apologized for his actions.
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"It wasn’t until I was back in the U.S. and looking through the CD of photos we were given by the photographer that I saw this one," Tweeden wrote about the photo on KABC.
"I felt violated all over again. Embarrassed. Belittled. Humiliated," she wrote. "How dare anyone grab my breasts like this and think it’s funny?"
Tweeden wrote that Franken, who was the headliner on the tour, had written some skits and told her he had a part for her, adding that she "agreed to play along."
"When I saw the script, Franken had written a moment when his character comes at me for a ‘kiss’. I suspected what he was after, but I figured I could turn my head at the last minute, or put my hand over his mouth, to get more laughs from the crowd," she wrote.
"On the day of the show Franken and I were alone backstage going over our lines one last time. He said to me, 'We need to rehearse the kiss.' I laughed and ignored him. Then he said it again. I said something like, ‘Relax Al, this isn’t SNL…we don’t need to rehearse the kiss.’"
She wrote Franken continued to insist and she got "uncomfortable."
"He repeated that actors really need to rehearse everything and that we must practice the kiss. I said ‘OK’ so he would stop badgering me. We did the line leading up to the kiss and then he came at me, put his hand on the back of my head, mashed his lips against mine and aggressively stuck his tongue in my mouth," she wrote.
"I immediately pushed him away with both of my hands against his chest and told him if he ever did that to me again I wouldn’t be so nice about it the next time."
She said she felt disgusted and violated. She added that she didn't tell anyone what happened at the time, but she was "angry."
Tweeden also said she fell asleep while on the plane back to the U.S. She said is wasn't until she saw the photo of Franken groping her that she told her husband what had happened and showed him the photo.
"I wanted to shout my story to the world with a megaphone to anyone who would listen, but even as angry as I was, I was worried about the potential backlash and damage going public might have on my career as a broadcaster," she wrote.
"But that was then, this is now. I’m no longer afraid."
She said she is sharing her story because there may be others.
"I want the days of silence to be over forever," she wrote.
Tweeden also issued a direct statement to Franken.
"Senator Franken, you wrote the script. But there’s nothing funny about sexual assault," she wrote.
"You knew exactly what you were doing. You forcibly kissed me without my consent, grabbed my breasts while I was sleeping and had someone take a photo of you doing it, knowing I would see it later, and be ashamed."
Franken said he does not remember the incident the same way but acknowledged the photo "wasn't" funny.
“I certainly don’t remember the rehearsal for the skit in the same way, but I send my sincerest apologies to Leeann. As to the photo, it was clearly intended to be funny but wasn't. I shouldn't have done it," he said in a statement.
Tweeden's comments come amid increased reports of sexual harassment in the workplace, including on Capitol Hill. Multiple women in Congress have come forward to say they have been victims of sexual harassment, prompting lawmakers to call for reform.
Rep. Jackie Speier (D-Calif.) said Tuesday the House has paid out $15 million in harassment settlements over more than a decade, though a spokesperson later clarified that figure does not only account for sexual harassment claims.
She said at a Tuesday hearing that two current members of Congress, one Republican and one Democrat, have been accused of sexual harassment.
Her comments come after multiple women have accused GOP Senate candidate Roy Moore of sexual misconduct. Moore is facing growing calls from top Republicans to step aside in the Alabama race, though he has indicated he plans to continue running.
This report was updated at 11:07 a.m. | – A radio host and former Playboy playmate says Sen. Al Franken assaulted her—and unlike some women coming forward with similar tales about other high-profile figures, Leeann Tweeden offered proof. In a first-person account at KABC, Tweeden says she was groped in December 2006 when she and the Democratic senator from Minnesota, then a comedian, were on a plane ride home from the Middle East, where they'd entertained troops as part of a USO tour. As she slept, Tweeden says Franken groped her breasts in a moment that was caught on camera. "It wasn't until I was back in the US and looking through the CD of photos we were given by the photographer that I saw this one," Tweeden says of the photo, which shows Franken grinning, his hands on Tweeden's clothed breasts. Earlier in the trip, Tweeden says Franken had also kissed her without her consent as the pair were rehearsing a skit. Franken decided their characters would kiss and "mashed his lips against mine and aggressively stuck his tongue in my mouth," Tweeden writes. "I felt disgusted and violated" and "wanted to shout my story to the world with a megaphone," she continues. "But even as angry as I was, I was worried about the potential backlash and damage going public might have on my career as a broadcaster," Tweeden writes. But "I've decided it's time to tell my story. #MeToo," she tweeted. Franken apologized Thursday but says he remembers the skit rehearsal differently, per the Hill. "As to the photo, it was clearly intended to be funny but wasn't," he says. "I shouldn't have done it." |
acute coronary syndrome refers to a collection of clinical signs resulting from myocardial acute ischemia that also includes acute myocardial infarction and unstable angina .
direct and indirect burden of coronary diseases was reported to be $ 142.1 billion in the us in 2005 . in iran ,
anticoagulants are vastly used in patients with acute coronary syndrome to prevent further occlusion of coronary arteries , and are available in two forms of regular heparin and low - molecular - weight heparin .
research shows that enoxaparin is more useful in the treatment of acute coronary diseases compared to regular heparin .
research has also shown that lower hospitalization costs due to earlier discharge and no need for partial thromboplastin time ( ptt ) control have made the use of enoxaparin more economical compared to regular heparin .
anticoagulants have side effects such as purpura , bruise , pain , hematoma , melena , hematuria , osteoporosis , and thrombocytopenia .
it results from blood leakage from the injured veins into the subcutaneous tissue , leading to pain , inflammation , and color change which usually reach their maximum within 48 h and are lowered 60 - 72 h after their formation .
the bruise caused by injection restricts the injection area , causes anxiety and a disturbance in body image , results in lack of treatment acceptance by the patient and treatment rejection , and finally , patient 's distrust in nurses efficiency .
therefore , nurses should use techniques which lead to modification of patients fear and anxiety and diminish further injury to the patients .
literature review shows that reduction of bruising has always been considered by the researchers . in australia , chan evaluated two methods of deltaparin injection ( within 10 and 30 sec ) to investigate the effect of injection duration on the bruise occurring in the injection site among 34 hospitalized stroke patients .
both lengths of duration of the injection were administered for each patient with a 12-h interval and the bruise size was measured 48 and 60 h after the injection was given .
their obtained results showed that the size of bruise was less in 30-sec injection compared to 10-sec injection .
chenicek investigated the effect of two injection durations of enoxaparin ( 10 and 30 sec ) on the bruising size in 34 hospitalized patients in florida .
they obtained no significant difference between the two methods of injection with regard to bruise size .
akpinar and celebioglu examined three techniques of tinazaparin administration and measured the bruise size in 36 hospitalized patients in turkey .
their techniques comprised injection for 10 sec ( technique a ) followed by injection for 30 sec after 24 h ( technique b ) , and technique c in which there was a 10-sec delay in the removal of needle after injection duration of 10 sec .
results showed that the bruise was of bigger size in technique a compared to the other two techniques .
investigated the duration of subcutaneous injection of heparin on the bruise size in two methods of routine injection ( for 4 - 10 sec in the control group ) and injection for 30 sec ( study group ) .
bruise size was calculated by multiplication of the length and width of bruise , 24 , 48 , and 60 h after injection .
results showed a significant difference in bruise size in the study group , compared to control , 24 and 60 h after injection ( p < 0.05 ) , but 48 h after injection , the difference was not significant .
investigated two injection techniques of 10- and 30-sec subcutaneous heparin injection in the right and left arms of the patients to evaluate the related bruise size in 80 patients hospitalized in two university hospitals in babol .
the obtained results showed that the bruise size that resulted from injection for 30 sec was significantly smaller than that of 10 sec injection ( p = 0001 ) .
the controversial results that have been obtained and lack of adequate research on enoxaparin led the researcher to conduct the present study to promote the quality of nursing care and provide the patients with peace and comfort .
this clinical trial aimed to define the effect of sodium enoxaparin subcutaneous injection on the bruise size .
inclusion criteria were acute coronary syndrome patients aged 35 - 75 years , newly hospitalized in the coronary care unit ( ccu ) , receiving 60 - 80 mg enoxaparin every 12 h , and expected to stay in the ward at least for 3 days .
pregnant women , those with coagulation problems , hematologic diseases , having an injury at the injection site , with dark color of skin , dermatological problems , as well as those patients > 75 years of age who needed medication dosage adjustment were excluded from the study .
this was a one - group study in which each patient underwent two techniques of subcutaneous injection ( 10 sec as the control method and 30 sec as the experimental method ) .
researcher selected 70 qualified patients through convenient sampling on the first 3 days of the week for 6 months in afshar hospital after obtaining approval from the ethics committee of shahid sadoughi university of medical sciences in yazd and an informed consent from the subjects .
firstly , subjects demographic characteristics such as age and sex were recorded in a data collection form from through interviews .
then , each patient was given a code on their questionnaire and those with odd and even code numbers underwent 30- and 10-sec injections , respectively , either on the right or left part of their abdomen .
prefilled syringes of enoxaparin , made by sanofi - aventis company , france were used .
an appropriate site of injection was selected in the lateral part of the abdominal area , about 5 cm around the navel .
after removal of the needle cap , the needle was inserted at 90 angle after pinching up the skin on the injection site .
after injection , the needle was smoothly removed and the site was slightly pressed by cotton wool .
next , the injection site was marked with a waterproof marker in a circle with radius 2.5 cm in order to prevent further injections on that site and to be able to evaluate the bruise size .
blue and red markers were used to mark 30- and 10-sec injection sites , respectively .
the subject was educated to prevent rubbing , touching , or pressing the injection site .
next injection was administered after 12 h on the other side in such a way that in patients for whom the first injection was of 10 sec duration , the next injection ( after 12 h ) was administered for 30 sec and vice versa .
finally , 24 and 48 h after injection , the size of bruising was marked on a transparent paper and measured by a checked paper ( mm ) .
all injections , measurements , and bruise size calculations were conducted by the principle researcher .
obtained data were analyzed by descriptive and non - parametric statistical tests ( mann - whitney and wilcoxon ) and spearman correlation coefficient through spss 18 with a significance level of p 0.05 .
most of the subjects ( 38.6% ) were in the age group 65 - 75 years , and the lowest percentage ( 12.9% ) was in the age group 35 - 44 years .
our obtained results of mean bruise size based on sodium enoxaparin subcutaneous injection showed that the mean bruise sizes at 24 and 48 h after 10-sec injection duration were 33.26 and 48.9 mm , respectively , while these values were 15.61 and 52.84 mm , respectively , after 30-sec injection .
wilcoxon test showed no significant difference in the bruise sizes in the two methods of 10 and 30-sec injection duration [ table 1 ] .
mann - whitney test showed no significant association between bruise size and subjects gender [ table 2 ] .
spearman correlation coefficient showed a significant association between bruise size and age ( p = 0.01 ) such that the bruise grew bigger with subjects increasing age [ table 3 ] .
mean bruise size ( mm ) 24 and 48 h after subcutaneous enoxaparin injection bruise size based on sex 24 and 48 h after subcutaneous enoxaparin injection for 10- and 30-sec duration association between bruise size and age in two methods of subcutaneous enoxaparin injection
our obtained results showed that there was no significant difference in the bruising size that resulted from 10- and 30-sec injection duration .
chenicek investigated the effect of duration of subcutaneous injection of enoxaparin on the size of the bruise .
their obtained results showed no significant difference in the mean size of bruise 48 h after 10- and 30-sec injection duration .
akpinar and celebioglu showed a significant difference between three methods of 10- and 30-sec injection duration and a 10-sec delay in removal of the needle after an injection of 10-sec duration ( p < 0.05 ) , and found that the bruise size was smaller in 30-sec injection method , compared to the other two methods . in the above - mentioned study
, the extent of bruise was measured 48 h after injection by a rubber ruler , and the longest diameter of the bruise was considered instead of calculating the bruise surface . in italy ,
showed that an increase in the duration of subcutaneous injection of enoxaparin for 30 sec can reduce the number of bruises , but not their size .
nair compared the size of bruises formed in the routine method of injection by the nurses ( between 4 and 10 sec ) in the control group and by injection administered for 30-sec duration in the study group . in their study , there were 100 subjects in each group of study and control .
bruise surfaces were calculated by multiplication of their widths by their lengths 24 , 48 , and 60 h after injections .
there was a significant difference in bruise sizes between the experimental and control groups 24 and 60 h after injection ( p < 0.05 ) , but the difference was not significant 48 h after injection .
the controversial results obtained can be due to the various measurement methods used to measure bruising size in different studies .
although various studies showed that an increase in duration of subcutaneous heparin injection can reduce the size of the bruise , longer time of injection necessitates careful administration by the nurses .
they should keep their hands stable to prevent dislocation of the needle during the procedure . on the other hand ,
the physical environment should also be peaceful and quiet to prevent patients excitation and sudden movements to lower the risk of bruise in injection site . in the present study , there was a significant association between subjects age and the bruise size , such that an increase in age increased the bruising size . in the study of zaybak and khorshid
, there was no significant association between the two methods of 10- and 30-sec injections .
the rate of collagen synthesis in skin markedly decreases with age by about 1% and the subcutaneous layer gets thinner due to loss of fat .
this affects the elasticity of the vascular system and elastic fibers are changed into thinner fragile fibers .
the process of aging causes a reduction in the number of fibroblasts , which are responsible for the synthesis of protein and collagen , leading to fragility of vascular walls .
these changes can lead to more hemorrhage , hematoma , and bruising in the elderly . in the present study , no significant difference was observed in the bruise size in relation to subjects gender , although the mean of bruise size was more in females compared to that of male subjects .
chan showed that the association between the bruise size and gender was significant just in the 10-sec method , such that the women developed a bigger bruise compared to men .
zaybak and khorshid showed a significant association between bruise size and gender just in the 10-sec injection technique and found that the bruise was more among men compared to women ( p < 0.05 ) , but the association was not significant in the 30-sec duration method .
trimarchi suggested the role of estrogen on the vascular structure of women and argued that women have more fragile veins compared to men .
the results obtained in this study show that duration of subcutaneous injection has no effect on the size of the bruise , but based on other studies , bruise size can be diminished by an increase in injection duration . during longer injection time , nurses should prevent dislocation of the needle and help the patient keep stable to lower the risk of a bruise resulting from the injection .
controversial results obtained in this context can be due to the various measurement methods used . therefore , further studies with a unique measurement method are recommended .
an investigation on the association between the bruise size that resulted from enoxaparin subcutaneous injection and body mass index ( bmi ) is suggested . | background : bruising is an unpleasant result of subcutaneous injection of enoxaparin , which causes physical discomfort , limitation of injection site , patient 's refusal of treatment , and distrust in nurses ability .
the application of techniques which reduce patients fear , anxiety , and physical damage is one of the tasks of nurses .
this clinical trial investigated the effect of duration of subcutaneous enoxaparin injection on the bruising size in acute coronary syndrome patients.materials and methods : seventy 35 - 75-year - old acute coronary syndrome patients hospitalized in coronary care units were selected randomly .
each subject received 10- and 30-sec duration of injections by a single researcher on both sides of the abdomen in 12-h intervals .
the bruising size was measured using a transparent millimeter measuring paper , 24 and 48 h after each injection .
data were gathered by a data recording form ( demographic and measurements data ) and analyzed by descriptive statistics and non - parametric tests through spss.results:results showed that the mean bruising sizes at 24 h after 10- and 30-sec injection were 33.26 mm2 ( 72.77 ) and 48.96 mm2 ( 99.91 ) , respectively , and at 48 h were 15.61 mm2 ( 142.02 ) and 52.48 mm2 ( 143 ) , respectively .
there was no significant relationship between the two techniques ( p > 0.05 ) , although the effect of age on bruising size was significant ( p = 0.01).conclusion : according to the findings of the present study , length of enoxaparin subcutaneous injection has no effect on the bruising size . |
brown dwarfs are intermediate in mass between stars and planets , making them important laboratories for testing theories about both classes of objects , including theories about atmospheres , binarity , and formation mechanism .
brown dwarfs are also potentially a laboratory to test theories of planet formation , but detecting planets that orbit brown dwarfs is challenging .
four super - jupiter planets orbiting brown dwarfs have been detected to date by three techniques : direct - imaging @xcite , radial - velocity @xcite , and microlensing @xcite . in the first three cases , the super - jupiter planet was within a decade in mass of its host and well separated from it , suggesting that these systems more resemble scaled down binary stars than they do the extreme mass - ratio systems that are likely to emerge from accretion disks . in the fourth case , the separation was substantially closer and the mass ratio somewhat more pronounced so that the planet could have formed through the core - accretion scenario that is thought to be the origin of the solar system s gas giants . with present technology , substantially lower - mass companions to brown dwarfs , composed primarily of ice and rock , can only be discovered using the gravitational microlensing technique .
microlensing does not rely on light from either the host or planet , but rather infers the existence and properties of these bodies from their deflection and magnification of light from a more distant star that is fortuitously aligned with the system . as such
, the low - luminosity of the brown dwarf and almost complete absence of light from its low - mass companion do not interfere in any way with the discovery process . in this paper
, we report the microlensing discovery of an intermediate system ogle-2013-blg-0723lb / bb composed of a venus - mass planet orbiting a brown dwarf . the system may be viewed either as a scaled down version of a planet plus star or as a scaled up version of a moon plus planet orbiting a star , suggesting that formation processes of companions within accretion disks around stars , brown dwarfs , and planets may be similar .
microlensing event ogle-2013-blg-0723 was discovered by the optical gravitational lensing experiment ( ogle - iv ) @xcite on may 12 , 2013 ( @xmath0 ) using its 1.3 m warsaw telescope at the las campanas observatory in chile . at @xmath1=@xmath2 , @xmath3 [ @xmath4 ,
the event lies in one of nine fields toward the galactic bulge that ogle observes @xmath5 , which is sufficient cadence to discover terrestrial planets .
in fact , the discovery was triggered by a short @xmath6day , @xmath7 brightening of the lensing event that was still in progress at the time of the announcement ( figure [ fig : one ] , left inset ) , and which was soon suggested to be of planetary origin .
hence , when the event underwent a second much larger ( factor 10 ) anomalous brightening 49 days later , ogle immediately recognized that it would be crucial to fully characterize this second anomaly . in particular , since such violent brightening is always caused by the source entering a `` caustic '' ( closed curve of formally infinite magnification see figure [ fig : two ] ) , a caustic exit was inevitable .
because these caustic crossings typically last only an hour or so and can occur at any time during the day , ogle contacted the microlensing follow up network ( @xmath8fun ) which operates a global network of narrow - angle telescopes capable of near 24-hour monitoring of individually important events . with the aid of real - time modeling that accurately predicted the time of the exit , the wise observatory 0.46 m telescope at mitzpe ramon , israel , obtained dense coverage of this exit ( figure [ fig : one ] , right inset ) .
the principal data were taken in @xmath9 band .
in addition , ogle obtained some @xmath10-band data in order to characterize the microlensed source .
finally , @xmath8fun obtained @xmath11-band observations from the 1.3 m smarts telescope at cerro tololo interamerican observatory in chile .
these are not used in the present analysis but will be important for the interpretation of future follow - up observations to cross - check the lens system parameters the light curve of ogle-2013-blg-0723 shows a systematic decline in the baseline . a similar long term linear trend ( of opposite sign )
was seen in ogle-2013-blg-0341 and was eventually traced to a nearby bright star that was gradually moving toward ( in that case ) the source star , so that more of its flux was being `` captured '' in the tapered aperture used to estimate the source flux .
we searched for such a moving bright star by examining the difference of two images , from 2004 and 2012 .
we indeed find a dipole from a bright star roughly @xmath12 away , which is the characteristic signature of such moving stars .
having identified the cause of this trend , we fit for it and remove it .
photometry of the event was done using a customized pipeline based on the difference imaging analysis method @xcite . because the photometric errors estimated by an automatic pipeline , @xmath13 , are often underestimated , the error bars are readjusted by @xmath14 where @xmath15 is a term used to make the cumulative distribution function of @xmath16 as a function of lensing magnification becomes linear and the other term @xmath17 is a scaling factor used to make
@xmath16 per degree of freedom ( dof ) becomes unity .
the former process is needed in order to ensure that the dispersion of data points is consistent with error bars of the source brightness and the latter process is required to ensure that each data is fairly weighted according to error bars .
the principal features of the light curve are a large double - horned profile near the peak , which is a signature of binary microlenses , and a short - lived spike two months earlier , which is characteristic of planetary companions .
modeling these features yields the mass ratios and instantaneous locations of the three bodies relative to the source trajectory .
see figure [ fig : two ] .
however , by themselves , these features do not yield either the physical or angular scale of the diagram , nor its orientation on the sky .
rather , the diagram is scaled to the `` einstein radius '' , which can be expressed either as an angle @xmath18 , or as a physical length @xmath19 projected on the observer plane . the source star and the earth s orbit act as `` rulers '' to determine these two quantities , as well as the angular orientation .
the source angular radius @xmath20 is known from its observed temperature and flux .
hence , when it passes over a caustic ( see figure [ fig : two ] ) , the finite extent of the source smears out what would be an extremely sharp peak for a point source ( figure [ fig : one ] , right inset ) .
second , earth s accelerated motion induces distortions in the light curve , which fix both @xmath19 relative the size of earth s orbit ( 1 au ) and the orientation of the diagram relative to that of earth s orbit , namely the ecliptic .
hence , we are able to display both the angular scale and physical orientation in figure 2 . the mass @xmath21 and distance @xmath22 of the lens are then given by @xmath23 the first equation follows from simple geometry .
once the distance is known , the second equation follow from einstein bending angle @xmath24 , where @xmath25 is the impact parameter of the lens - source approach .
see the graphical presentation of the formalism in @xcite .
ll[lr ] @xmath26 & 4126.8/4073 + @xmath27 ( hjd ) & 6484.526 @xmath28 0.037 + @xmath29 & -0.079 @xmath28 0.002 + @xmath30 ( days ) & 68.48 @xmath28 0.01 + @xmath31 & 5.07 @xmath28 0.02 + @xmath32 & 3.11 @xmath28 0.02 + @xmath33 ( rad ) & -1.195 @xmath28 0.003 + @xmath34 & 0.97 @xmath28 0.02 + @xmath35 @xmath36 & 6.61 @xmath28 0.01 + @xmath37 ( rad ) & -4.936 @xmath28 0.005 + @xmath38 @xmath39 & 1.40 @xmath28 0.02 + @xmath40 & -0.05 @xmath28 0.01 + @xmath41 & 1.35 @xmath28 0.02 + @xmath42 @xmath43 & 0.81 @xmath28 0.02 + @xmath44 @xmath43 & -0.50 @xmath28 0.02 + @xmath45 & 19.825 @xmath28 0.006 + @xmath46 & 20.181 @xmath28 0.008 full modeling of the light curve ultimately requires a total of 19 parameters , including 14 parameters to describe the lensing system and five flux parameters . some of these manifest themselves in quite subtle effects .
the modeling therefore proceeded in several distinct phases .
first , we determine the principal parameters describing the binary - lens system by removing the data for 25 days around the planetary perturbation and fitting the remaining light curve to seven system parameters plus four flux parameters ( two for each observatory ) .
these nine include three parameters to describe the underlying point - lens event @xmath47 , three to describe the perturbations induced by the binary companion @xmath48 , one to describe the ratio of the source radius to the einstein radius , @xmath49 , and the two - dimensional microlens parallax vector @xmath50
. here @xmath27 is the time of closest approach to a reference point in the geometry , which is chosen as the `` center of magnification '' of the caustic traversed by the source , @xmath29 is the impact parameter in units of @xmath18 , and @xmath30 is the time required for the source to cross @xmath18 .
we choose @xmath18 as the einstein radius of the mass associated with the caustic , which is the total mass for the close - binary case , and the mass of the binary component located closer to the source trajectory for the wide - binary case .
this convention leads to similar @xmath30 for the two cases , e.g. @xcite .
the three binary parameters are the separation of the components in units of @xmath18 , the ratio of the companion to primary component masses , and the angle of the source trajectory relative to the binary axis at @xmath27 ( since parallax causes this to change with time ) .
the amplitude of the parallax vector is @xmath51 , while its direction is that of the lens - source relative proper motion ( in the geocentric frame ) .
in contrast to the lens - source trigonometric relative parallax @xmath52 , which is a scalar quantity , the microlens parallax requires two parameters because the lens is not directly observed , so the orientation of the lens - source separation relative to the ecliptic is not known a priori .
see @xcite .
normally , one would not include parallax in the initial fit , but in this case it is so large that the projected einstein radius is substantially smaller than earth s orbit , @xmath53 , so that there is no even approximately good solution without including @xmath54 in the fit . with this parameterization
, we find an excellent fit for the wide - binary case @xmath55 but only a crude approximation to the observed light curve for @xmath56 .
we then incorporate two - parameter orbital motion , essentially the instantaneous relative transverse velocity of the components in einstein - radius units .
this refinement results in negligible improvement for the @xmath57 solution , but dramatic improvement in the @xmath56 solution , so that the two models provide qualitatively similar approximations of the data
. however , it is found that the @xmath56 case is unlikely due to various reasons as discussed in appendix .
we then restore the data from the planetary perturbation and add five additional parameters to the fit : @xmath58 , where @xmath59 . here
@xmath60 are the separation and mass ratio of the planet relative to its host ( the smaller component of the binary ) , @xmath37 is the angle between binary axis and the planet - host axis at @xmath27 , and @xmath61 is the two dimensional projected velocity of the planet relative to its host .
table [ table : one ] shows the best fit parameters . in figure
[ fig : three ] , we also present the distribution of @xmath62 in the parameter space in order to show the uncertainties and correlations between the parameters .
the microlens parallax signal is quite strong ( @xmath63 ) , but since the amplitude @xmath64 is one of the largest ever detected and hence quite unusual .
therefore , it is prudent to check whether this signal is coming mainly from one part of the light curve , which would be suspicious , or from the entire magnified portion of the light curve , as one would expect .
figure [ fig : four ] shows that in fact the signal is coming from the whole magnified light curve .
it also shows that planetary orbital signal , while much weaker ( @xmath65 ) , is also broadly based .
as expected , the orbital signal is more compact than the parallax signal .
because the light curve is well covered , the parameters are well determined .
however , the solution is still subject to three well known discrete degeneracies .
first , there is a degeneracy between pairs of companion mass ratio and normalized separation @xmath66 , with one lying inside the einstein radius @xmath67 and the other outside .
this degeneracy is fully understood at first @xcite and second @xcite order for the case that the binary is approximated as static .
we find that within this context there is no `` close '' solution , i.e. , @xmath68 between close and wide solutions . however , if both close and wide binary models are permitted two degrees of orbital motion , i.e. @xmath42 and @xmath44 , then the wide solution shows essentially no improvement while the close solution improves dramatically and matches the wide solution . in appendix , we discuss the mathematical and physical nature of this new variant of the close / wide degeneracy and show that it implies that the wide solution is strongly favored .
we also present additional corroborating arguments that this is the case .
we therefore consider only the wide solution .
second , if the source lay on the ecliptic , the entire solution could be `` flipped '' relative to the ecliptic without changing the light curve . since
the source lies just @xmath69 from the ecliptic , this degeneracy is close to exact , with the preferred solution favored by only @xmath70 .
while this is enough to clearly favor one solution , the main point is that the two solutions yield almost identical physical implications .
finally , figure [ fig : two ] shows the small planetary caustics just to the right of the source trajectory . in principle , there could be another solution with these caustics just to the left . however , this geometry is unable to reproduce the long slow `` depression '' that follows the planetary anomaly and is due to a demagnification `` valley '' that follows the axis defined by the two small caustics .
hence , the solution is both unique and measured with good precision .
we determine the angular source radius @xmath20 based on its de - reddened color @xmath71 and brightness @xmath72 @xcite , which we determine from their offsets from the centroid of the red giant clump @xmath73_{0,\rm clump } = ( 1.06,14.45)$ ] @xcite , under the assumption that the source and the clump giants suffer similar extinction .
figure [ fig : five ] gives a graphic representation of this procedure , and also shows the position of the star ( or ensemble of stars ) that are blended with the source .
that is , in each band , the light - curve flux is modeled as @xmath74 , where @xmath75 is the magnification .
the source and blend magnitudes are then derived from the fit parameters @xmath76 and @xmath77 , respectively .
we find @xmath78 . from this color and flux , we derive @xmath79 by converting @xmath80 @xcite and then applying a color / surface brightness relation @xcite .
the derived color is well blueward of the overwhelming majority of galactic bulge stars , except for horizontal branch stars , which are substantially brighter .
hence , the source is almost certainly in the galactic disk .
disk sources are rare in general ( a few percent ) partly because the source must be farther than the lens with the lenses being mostly in the bulge or fairly far in the disk , and partly because the column density of bulge stars is higher than for disk stars .
however , given that this particular lens lies far in the foreground @xmath81 ) , it is not unexpected for the source to lie in the disk .
based on the source color and magnitude , we estimate its distance @xmath82 .
the exact distance plays no role in the determination of @xmath20 because this depends only on the flux @xmath83 , not the luminosity @xmath84 and distance separately , provided that the source lies behind essentially all the dust .
given that the source sits 360 pc above the galactic plane , this is almost certainly the case .
the uncertainty in the source distance also enters into the uncertainty in the lens distance through equation ( [ eq2 ] ) . in practice , however , this leads to an error in source distance of only 4% , which is small compared to other sources of errors .
finally , we note that the source color indicates a temperature @xmath85k , which leads to an estimate of the limb - darkening coefficient ( needed for modeling the caustic exit ) of @xmath86 @xcite . in most microlensing events ,
the blended light @xmath77 is just a nuisance parameter , but in the present case it is potentially very important .
we first note that while the @xmath9-band magnitude is secure , the error in the @xmath87 color ( not shown ) is quite large .
first , the formal error of the fit is 0.2 mag .
in addition , in contrast to the source flux , which is determined solely from changes in brightness , the blend flux depends on the accuracy of the baseline photometry . this can be corrupted by bright nearby blends , which are plainly visible on the images , and by stars that are too faint to be identified .
hence , we consider the color to be only indicative and do not make use of it in further discussion .
however , the @xmath9 band measurement is too bright to be the ogle-2013-blg-0723la by about 1.5 mag . to further understand the origin of this light
, we measure the position of the source relative to the `` baseline object '' , which is an unresolved blend of the source with the star or stars giving rise to @xmath77 .
we find @xmath88mas .
since the blend contains 43% of the baseline light , this implies that it is naively offset from the source by @xmath89mas .
however , while the source position can be measured extremely well because it becomes highly magnified , the `` baseline object '' is subject to contamination from unseen stars as well as the wings of nearby bright stars .
we conclude that the centroid of blend light is separated from the source by @xmath90mas . because the surface density of stars @xmath91 in this field
is @xmath92 @xcite , the probability that this blended light lies so close to the source ( and lens ) by chance is @xmath93 .
it is therefore most likely a companion to either the source or lens .
this issue can be resolved by obtaining ao images at two epochs to determine whether its proper motion is consistent with the source or lens .
if it proves to be associated with the lens , then this is a four - body system consisting of a brown dwarf orbited by a venus - mass planet , with both orbiting a very low - mass star , and with this entire group orbiting another star that is roughly double the mass of the star that contributed to the microlensing event .
ll[h ] mass of the planet & @xmath94 + mass of the host & @xmath95 + mass of the binary companion & @xmath96 + distance to the lens & @xmath97 kpc + projected planet - host separation & @xmath98 au + projected separation between binary components & @xmath99 au + relative lens - source proper motion ( geocentric ) & @xmath100 mas / yr + relative lens - source proper motion ( heliocentric ) & @xmath101 mas / yr the principal physical parameters are given in table [ table : two ] .
from the determined masses of the individual lens components , it is found that the lens is a triple system that is composed of a venus - mass planet ( 0.69 @xmath102 ) orbiting a brown - dwarf host ( 0.031 @xmath103 ) that is accompanied by a low - mass star ( 0.097 @xmath103 ) .
the projected planet - host separation is 0.34 au , while the separation between the binary components is 1.7 au .
the system is located at a distance 490 pc toward the galactic center .
note that we give the proper motion in both the geocentric frame in which the measurements were actually made , and the heliocentric frame , which will be useful for comparison with future observations . since @xmath22 is known , the conversion from geocentric to heliocentric frames is straightforward . from figure
[ fig : two ] or table [ table : one ] , the planet s projected position is @xmath104 times closer than the stellar companion .
if the planet were orbiting the more massive companion , this would occur with probability @xmath105 .
in addition , in order to ensure stability of the 3-body system , the brown dwarf would have to be behind ( or in front of ) the star - planet system by a at least factor of 3 larger distance than the projected separation of the brown dwarf and star .
this chance alignment further reduces the probability by a factor @xmath106 . hence , while this configuration is possible in principle , it has extremely low probability .
a very similar argument applies to a circumbinary configuration , in which the planet s orbit is at least three times larger than the separation between the brown dwarf and star , but just happens to be seen in projection close to the brown dwarf .
ogle-2013-blg-0723lbb is a missing link between planets and moons .
that is , its host ogle-2013-blg-0723 lb , being a brown dwarf in orbit around a self - luminous star , is intermediate between stars and planets , in both size and hierarchical position .
moreover , the scaled mass and host - companion separation of ogle-2013-blg-0723lb / bb are very similar to both planets and moons in the solar system .
see table [ table : three ] .
both uranus and callisto are believed to have formed in the cold outer regions of their respective accretion disks , and are mostly composed of the raw materials of such regions : ice with some rock . in the case of uranus
, it is believed to have been formed closer to the current location of saturn ( 10 au ) and to have migrated outward . in the table ,
the companion - host separations are scaled to the host mass .
this is appropriate because the `` snow line '' , the inner radius at which icy solids can form ( 2.7 au in the solar system ) increases with host mass , probably roughly linearly .
a plausible inference from the first three lines of table 2 is that these processes scale all the way from solar - type stars hosting planets , to brown dwarfs hosting `` moon / planets '' , to giant planets hosting moons .
however , while ogle-2013-blg-0723lbb is almost certainly orbiting ogle-2013-blg-0723 lb today , we can not guarantee that it was born there .
planets in relatively close binaries ( like ogle-2013-blg-0723la , b ) can jump from one star ( or in this case , brown dwarf ) to the other , if the system is dynamically perturbed @xcite . if this is what happened to ogle-2013-blg-0723lbb , then would have been captured from an orbit around ogle-2013-blg-0723la to its current orbit around ogle-2013-blg-0723 lb .
it would then be similar to triton , which was captured by neptune out of solar orbit .
table [ table : three ] shows that the neptune - triton system in its current configuration is also not terribly different than a scaled version of ogle-2013-blg-0723lb / bb
. it will be interesting to model the dynamics of the triple system ogle-2013-blg-0723la , b , bb , but it would be premature to do so .
this is because there is likely a fourth member of this system that is more massive and luminous than the other three , and which is separated by of order 100 au or less .
if confirmed , this member could significantly impact the system dynamics via the lidov - kozai mechanism .
the principal evidence for this fourth member is that there is excess light in the aperture that is too bright to be the primary star ogle-2013-blg-0723la , and is so closely aligned with the source that it is unlikely to be a random interloper . because the source flux is known from the @xmath11-band light curve ( which is not included in the present analysis ) , it will be straightforward to subtract out the source light from a high - resolution adaptive optics ( ao ) image and determine the exact location of the blended light .
if well separated , then its association with the lens can be established from its proper motion , derived from observations at two epochs , which can be compared with table [ table : two ] .
if directly superposed in the ao images , then it is almost certainly associated with either the source or the lens because of the extremely low probability of a random interloper .
the two possibilities can be distinguished based on the apparent color because the source is highly reddened by dust , but the lens sits in front of the great majority of the dust .
ogle-2013-blg-0723lbb is the second terrestrial mass planet orbiting one member of a binary system composed of two very low mass objects .
the other was ogle-2013-blg-0341lbb .
gould et al .
@xcite showed that if all low - mass stars were in such systems , roughly one should have been detected .
they noted that no strong statistical inference could be derived from this fact because , for example , if only 1% of low - mass stars were in such systems , there would be a 1% chance to find one . because the question about the frequency of these systems was being framed a posteriori , a 1% effect is not particularly significant .
however , ogle-2013-blg-0723lbb reproduces three of the four elements that went into their estimate of the frequency of such detections , namely small probability of passing by the planetary caustic , small probability of crossing the central ( binary ) caustic , and location in a high - cadence ogle fields .
the fourth criterion , source magnitude brighter than @xmath107 , is not satisfied , since @xmath108 .
if the limit were extended to @xmath109 , the total number of available events would roughly double .
hence , the prediction would rise to two . with
two predicted and two detected , the probability that these are extremely rare drops roughly as the square , i.e. , roughly @xmath110 probability of this occurring by chance if only 1% of these stars were in such systems .
hence , while there is still no compelling evidence that these systems are extremely common , at least they are not extremely rare .
further , the current detections remain consistent with the hypothesis that these systems are ubiquitous .
lcc[h ] uranus / sun & 4.4 & 19 + ogle-2013-blg-0723lbb / b & 6.6 & 11 + callisto / jupiter & 5.7 & 13 +
triton / neptune & 21 & 46 the ogle project has received funding from the national science centre , poland , grant maestro 2014/14/a / st9/00121 to au .
work by c.h . was supported by creative research initiative program ( 2009 - 0081561 ) of national research foundation of korea .
a.g . and b.s.g
acknowledge support from nsf ast-1103471 .
, a.g . , and r.w.p .
acknowledge support from nasa grant nnx12ab99 g .
in the main text of the paper , we stated that the wide solution was consistent with a static binary while the close solution required substantial orbital motion to match the wide - solution light curve . at first sight
this seems qualitatively reasonable since close binaries have shorter periods than wide ones .
however , only one of these solutions corresponds to the physical system , while the other is merely a mathematical reflection of it .
hence , the real question is not whether each solution is physically plausible but what is the relative likelihood where each solution , if it were real , could generate the other as a doppelganger . before addressing this
, some comments must be in order as why this degeneracy is appearing in this case and how likely it will be to appear generically .
in the simplest cases two solutions appear because to first order , the quadrupole expansion of the close - binary potential and the tidal expansion of the wide - binary potential are identical and so ( to this order ) produce identical caustics @xcite . contemporaneously , it was noticed that in more typical cases , the degeneracy could remain extremely severe even though the caustics were not actually identical and , indeed , appeared rotated relative to each other ( fig .
8 of @xcite ) .
this was ultimately explained by carrying out the analysis to second order @xcite .
that is , an additional degree of freedom ( basically , rotation ) could compensate for the slower convergence of the potential . for wide binaries
, the potential converges more slowly as the mass ratio of the companion increases and as its separation gets closer .
this is well illustrated by small mass - ratio , e.g. , planet / star , systems .
topologically , the two caustics are the same , but geometrically they are very different .
the planet has a relatively weak effect on the stellar potential , meaning that the star s caustic ( `` central caustic '' ) is well - described by low - order terms and hence subject to the close / wide degeneracy . by contrasts ,
the planetary caustic is strongly perturbed and not subject to this degeneracy ( unless the separation is very large ) . in the present case ,
the caustic feature in the light curve of the wide solution is associated with the lower - mass companion , and the mass ratio is relatively large .
hence , one expects that ( as in the planetary case ) higher order terms will play a relatively large role . and indeed they prove to be too large to permit the degeneracy analyzed by @xcite .
orbital motion then provides the additional degree of freedom to compensate for the non - trivial higher - order terms .
consider then a wide binary that is qualitatively similar to the present case .
regardless of details , its light curve can always be mimicked by including the appropriate amount of orbital motion . on the other hand , consider a ( real ) close binary with the @xmath111 parameters predicted by the wide binary but with so far unspecified orbital parameters .
can this system `` generate '' a static wide binary with the same light curve ?
the answer is : only if its orbital parameters happen to lie in a narrow range around those predicted by the wide pair . otherwise , the static wide binary would have been consistent with a wide range of close - binary orbital motions . because @xmath62 is quite large , the fine - tuning requirements of the close solution are severe .
this is the principal reason that we discount it .
however , in addition , if the close solution is spurious and merely tuned to the mathematical requirements of matching the wide solution , it is likely to have characteristics that are atypical of real systems , which can be a further indication of its spurious nature .
we note two such features .
first , the ratio of projected kinetic to potential energy @xcite is quite low @xmath112 compared to typical values @xmath113 .
the three physical effects that can produce low @xmath114 are 1 ) it is near apocenter of an extremely eccentric orbit , 2 ) our line of sight happens to be almost tangent to the orbital velocity vector , or 3 ) we happen to view the system edge on , so that its semi - major axis is much larger than its projected separation . since the unprojected ratio typically has values @xmath115 reducing this number by a factor @xmath116 via projection effects requires some fine tuning .
however , in the present case there is an additional complication : the third option generates the need for an additional low probability event .
that is , if the two stars are extended along the line of sight , then either this projection must be very great to allow the planet to have a stable orbit around one star ( actually brown dwarf ) , to the planet itself must be seen in projection next to the pair despite the fact that its orbit is at least three times that of the extended binary .
finally , we note that the source star is four times fainter in the close model .
since its color ( so spectral type ) is still the same , this places it twice as far as in the wide solution , where the density of such stars is about a factor 40 smaller .
this is somewhat compensated by the eight times larger phase space , but still does further reduce the probability of this solution by a factor 5 .
all the arguments given above make the close - binary solution very unlikely but they do not exclude it
. however , this solution can also be tested by direct imaging .
since there are compelling reasons to conduct such imaging , possibly at several epochs , no special effort is required to do this . if these observations reveal a blend that is substantially brighter than the source , then the close solution will be confirmed .
the expected baseline magnitudes of the source and blend are @xmath117 , respectively .
if the wide solution is correct , we expect the blend and source to be comparable ( depending on their @xmath118 colors ) .
99 afonso , c. , et al .
2000 , , 532 , 340 alard , c. & lupton , r. h. 1988 , , 503 , 325 an , j. h. 2005 , , 356 , 409 bensby , t. , et al .
, 2011 , , 533 , 134 bessell , m. s. & brett , j. m. 1988 , , 100 , 1134 chauvin , g. , et al .
2004 , , 425 , l2 claret , a. 2000 , , 363 , 1081 dominik , m. 1999 , , 349 , 108 dong , s. , et al .
2009 , , 695 , 442 gould , a. 2000 , , 542 , 785 gould , a. , et al . , 2014 , science , 345 , 46 gould , a. , & horne , k. 2013 , , 779 , 28 griest , k. , & safizedah , n. 1998 , , 500 , 37 han , c. , et al .
, , 2013 , 778 , 38 holtzman , j. a. , et al .
1998 , , 115 , 1946 joergens , v. , & mller , a. 2007 , , 666 , l113 kervella , p. , et al .
2004 , , 426 , 297 kratter , k. m. & perets , h. b. 2012 , , 753 , 91 nataf , d .
h. , et al . , 2013 , , 769 , 88 todorov , k. , et al . 2010 , , 714 , l84 udalski , a. , szymaski , m.k . & szymaski , g. 2015 , acta astron . , 65 , 1 woniak , p. r. 2000 , acta astron . , 50 , 421 yoo , j. , et al . , 2004 , , 603 , 139 | the co - planarity of solar - system planets led kant to suggest that they formed from an accretion disk , and the discovery of hundreds of such disks around young stars as well as hundreds of co - planar planetary systems by the _ kepler _
satellite demonstrate that this formation mechanism is extremely widespread .
many moons in the solar system , such as the galilean moons of jupiter , also formed out of the accretion disks that coalesced into the giant planets .
we report here the discovery of an intermediate system ogle-2013-blg-0723lb / bb composed of a venus - mass planet orbiting a brown dwarf , which may be viewed either as a scaled down version of a planet plus star or as a scaled up version of a moon plus planet orbiting a star . the latter analogy can be further extended since they orbit in the potential of a larger , stellar body . for ice - rock companions formed in the outer parts of accretion disks , like uranus and callisto , the scaled masses and separations of the three types of systems are similar , leading us to suggest that formation processes of companions within accretion disks around stars , brown dwarfs , and planets are similar . |
A firefighters uses a hose and works to put out massive flames in the San Bernardino Forest.
Flood waters overtook a couple hiking near Mill Creek Crossing in Forest Falls Tuesday afternoon, San Bernardino County Fire spokesman Chris Prater said.An off-duty sheriff's deputy heard the couple calling for help. He was able to save the young woman, but the man was swept away.The body of the victim, a Rancho Cucamonga man in his 20s, was found shortly after 7 p.m., Prater said.A powerful storm cell packed with heavy rain and hail moved through, creating a quick-moving river runoff that trapped the young couple.Parts of the Inland Empire saw flash-flood warnings Tuesday as Riverside and San Bernardino counties were pelted with hail.A flash-flood warning were in effect for Riverside and San Bernardino counties for most of the day.A thunderstorm producing heavy rain between Hesperia and Apple Valley caused flash flooding and mudslides.Residents were warned that excessive rainfall could cause flash flooding or mudslides, particularly within the Lake Fire burn area.The Lake Fire, which erupted on June 17 in a remote area of the San Bernardino Mountains, burned over 30,000 acres.The NWS said most flood-related deaths occur in automobiles and warned people not to attempt to cross water-covered bridges, dips or low-water crossings. ||||| A man who was out on a first date was swept away to his death after the couple was caught in a flash flood while hiking in the mountain community of Forest Falls. Robert Kovacik reports for the NBC4 News at 11 p.m. on Tuesday, Sept. 8, 2015. (Published Tuesday, Sept. 8, 2015)
A man who was out on a first date was swept away to his death after the couple was caught in a flash flood while hiking in a mountain community east of Los Angeles, fire officials said.
As a rainstorm pummeled the Inland Empire on Tuesday, the couple attempted to cross a waist-deep river hand-in-hand near Alder and Island drives in Forest Falls, said San Bernardino County Fire Department spokesman Bret Raney.
The powerful current pulled the couple under water. She was unable to hang on to him and watched helplessly as he was swept away.
Chris Kostiuk, an off-duty San Bernardino County sheriff's deputy who was also hiking in the area, heard her screams and ran to pull her from the water.
2015 Southern California Images in the News
"She said she was on a date. Just met the guy, first date," he said.
Hiker Carlos Rojas witnessed how dangerous the usually peaceful river had suddenly become.
"It is scary," he said. "We just found her in a state of shock. She was screaming for help."
Rescuers called off a search for the man after his body was found. His name was not released because his relatives had not been notified. Raney said he was in his late 20s.
The woman was reunited with her family. ||||| Flash floods in Victorville left some motorists stranded and in need of rescue. Gadi Schwartz reports for NBC4 News at 11 p.m. on Tuesday, Sept. 8, 2015. (Published Wednesday, Sept. 9, 2015)
A flash flood warning was issued Wednesday for San Bernardino County during punishing monsoonal weather in Southern California.
The warning was in effect for the Big Bear area, including the Lake Fire burn area, until 6:30 p.m. Tuesday due to lightning, hail and between 1 and 2 inches of rain per hour from monsoonal flow in Mexico.
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The alert comes as temperatures and humidity levels rose to uncomfortable levels across Southern California at the start of a heat wave expected to last until early next week, and perilous conditions characterized by strong rip currents and high surf will prevail along the coast until tonight.
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Flash flooding submerged some major intersections and streets with water in Victorville and made it difficult for motorists to travel.
One motorist who got out of his vehicle was swept away by the flood and ended up in a storm drain. Rescuers recovered the man but his condition was unknown.
At Victor Valley College in Victorville, rain left some buildings with leaks and the storm knocked over several trees around the campus.
"The combination of high pressure aloft and weak offshore flow will bring very hot weather to much of Southwestern California," according to the National Weather Services.
2015 Southern California Images in the News
Forecasters said "slight cooling" is expected Friday and Saturday, although temperatures will not be returning to normal until early next week.
"The prolonged heat wave will bring a risk of heat-related illness through much of the week. Those at highest risk include children, the elderly, and pets without adequate shelter," warned the statement, which noted that the heat would heighten electricity use throughout the region, "increasing the threat of power outages."
The NWS forecast highs today in the mid 90s in metropolitan Los Angeles and the low 100s in the San Gabriel, San Fernando, Santa Clarita and Antelope valleys as well as inland Orange County.
"Maximum temperatures will reach dangerous levels across much of Southern California this week," according to the NWS.
"The peak of the heat wave will be Wednesday and Thursday, although today and Friday will only be a few degrees cooler. It will be cooler over the weekend, although maximum temperatures will remain well above normal. Temperatures are expected to return to near normal by early next week."
Temperatures Tuesday and during the rest of the heat wave will be running 10-15 degrees higher than normal, said NWS meteorologist Kathy Hoxsie.
The high heat is being attributed to high pressure developing over the region, combined with the fact that only weak winds are blowing in from the ocean.
Also afflicting the region is high humidity, which is forecast to be at the 50 percent level in the coastal plains -- the norm is 20-30 percent -- and around 40 percent in valley areas, compared to the teens, which would be normal, Hoxsie said.
The humidity is attributed to lingering moisture from Hurricane Linda. The conditions prompted the NWS to issue an excessive heat warning for the San Gabriel and Santa Monica mountains in both Los Angeles and Ventura counties, with highs of 105 expected at low elevations, and the San Fernando, San Gabriel and Santa Clarita valleys.
It will be in force from 11 a.m. today until 8 p.m. Thursday. Normally, excessive heat warnings are issued when humidity levels stand to make temperatures feel even hotter than they are, but in this instance the warning would have been issued in any event as a result of the high temperatures, Hoxsie said.
Forecasters said those at greatest risk of suffering heat-related ailments were infants, the elderly, the homeless, outdoor workers and people taking part in outdoor activities in the heat. They urged residents to drink plenty of water; wear light-colored and lightweight clothing; stay out of the midday sun; check on neighbors and the elderly to make sure they are not being overwhelmed by the heat; and never, ever leave children, the elderly, or pets in a vehicle parked in hot weather.
The NWS forecast sunny skies today and highs of 81 in San Clemente; 82 in Avalon; 85 in Newport Beach and Laguna Beach; 85 in Newport Beach and Laguna Beach; 86 at LAX; 92 on Mount Wilson; 97 in Irvine, Anaheim, Long Beach and downtown L.A.; 98 in Mission Viejo and San Gabriel; 99 in Fullerton; 100 in Yorba Linda, Palmdale and Burbank; 101 in Lancaster; 102 in Pasadena and Saugus; and 105 in Woodland Hills.
Temperatures will be a couple of degrees higher in several communities on Wednesday and start a cooling trend on Friday. By Monday, many communities that will have withstood temperatures in the 90s and above will be back in the 80s. Along the coast, high surf is expected through tonight as a result of a long-period swell in the Pacific, said the NWS, adding that the highest surf -- 3 to 6 feet, with 7-foot sets -- will pound south- and southwest-facing beaches.
"Strong, frequent rip currents will continue to be a significant hazard," an NWS statement said. Anyone who plans to swim in the ocean today should do so near a lifeguard, the NWS urged, adding that beachgoers must avoid climbing on rocks or jetties because of the risk of being scooped up by "sneaker waves." ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. ||||| FOREST FALLS (CBSLA.com) — A hiker was killed Tuesday after a thunderstorm triggered a flash flood in the San Bernardino National Forest.
The victim was hiking with his girlfriend in the Forest Falls area, south of Big Bear Lake, when she said fast-moving water swept her boyfriend away.
“The water, according to the female, waist-deep, and they tried to cross it, which is extremely inadvisable. And again, she was able to self-extricate, and he was not able to,” said Capt. Brett Raney of the San Bernardino County Fire Department.
Rescue crews found for the 29-year-old man’s body in the waters about a mile away from where he disappeared.
They also found a backpack with keys, cell phones and a hydration pack often used by hikers. It’s not clear if the items belonged to the victim, whose name has not been released.
His girlfriend was also injured. | – A couple's first date in California's San Bernardino National Forest turned out to be anything but romantic yesterday as the remains of Hurricane Linda sent a storm of heavy rain and hail over the area. While hiking in Forest Falls, east of Los Angeles, the pair became trapped in a flash flood and attempted to cross a waist-deep river runoff hand in hand, a fire official tells NBC Los Angeles. The current soon pulled both underwater and the frantic woman watched as her date was swept away. An off-duty police officer heard her screams and was able to pull her from the water, while another hiker also ran to help. "We just found her in a state of shock," he says. Police called off the search for the Rancho Cucamonga man, 29, when a body was found about a mile from where he vanished, report KABC and CBS Los Angeles. A hiker's backpack was also found. Also in San Bernardino County yesterday, fire officials say they had to rescue an individual whose vehicle was swept away in a flash flood, per the AP. NBC Los Angeles reports a man—it's not clear if he's the same person—exited his vehicle and was swept into a storm drain. He was found alive, though his current condition is unknown. A flash flood warning is still in effect for the area; trees have been uprooted and streets are still filled with water. (This first date also ended badly.) |
the origins of @xmath0 violation in fundamental physics theory remain a mystery .
the @xmath2 system provides excellent laboratories to probe @xmath0 violating new physics , since new particles beyond the standard model ( sm ) may enter the loop - mediated @xmath2 meson mixing process , leading to discrepancies of @xmath0 asymmetries with their sm expectations .
the effective hamiltonian of the @xmath2@xmath3 system can be written as @xmath4 where @xmath5 and @xmath6 hold under the assumption of @xmath7 invariance .
the off - diagonal elements @xmath8 and @xmath9 are responsible for @xmath2@xmath3 mixing .
diagonalizing the hamiltonian matrix leads to the two mass eigenstates @xmath10 ( @xmath11 and @xmath12 denote heavy and light , respectively ) , with mass @xmath13 and decay width @xmath14 .
@xmath10 are linear combinations of flavour eigenstates with complex coefficients @xmath15 and @xmath16 that satisfy @xmath17 : @xmath18 .
new physics contribution in the mixing process could affect the mass difference between the heavy and light mass eigenstates , @xmath19 , the decay width difference between the light and heavy mass eigenstates , @xmath20 , and the semileptonic asymmetry @xmath21 , where @xmath22 is a convention - independent phase difference .
the decay @xmath1 ( charge conjugate is implied in this paper ) proceeds dominantly via a tree level @xmath23 diagram that is well understood in the sm .
this makes it an ideal place to search for demonstration of new physics with only limited hadronic uncertainties . ignoring the
doubly cabibbo - suppressed penguin contributions in the @xmath23 decay process , we denote the phase difference between the amplitude for a direct decay of @xmath2 to a @xmath0 eigenstate @xmath24 with eigenvalue @xmath25 and the amplitude for decay after oscillation as @xmath26 where @xmath27 and @xmath28 are the decay amplitudes of @xmath29 and @xmath30 , respectively .
( discussions about controlling the effect of the penguin diagrams in the @xmath23 decay process can be found in section 3.2 . of ref .
@xcite and references therein . )
@xmath31 is very precisely predicted within the sm , @xmath32 rad @xcite , however , it could be altered by new physics contribution in @xmath2 mixing .
note @xmath33 is a good approximation unless either the @xmath23 decay process or @xmath9 is affected by physics beyond the sm . neglecting the small @xmath0 violation in @xmath2 mixing , _
i.e. _ assuming @xmath34 , we can write the mixing - induced @xmath0 asymmetry as @xmath35 . thus @xmath31 can be extracted from the time - dependent @xmath0 asymmetry in the decay @xmath1 , measurement of which requires to identify the flavour of the initial @xmath2 or @xmath3 mesons .
the final state of the decay @xmath1 is an admixture of two @xmath0-even and one @xmath0-odd eigenstates .
there is also a @xmath0-odd final state due to s - wave @xmath36 contribution ( specified using the subscript `` s '' ) under the @xmath37 peak .
an angular analysis is needed to statistically disentangle the four @xmath0 eigenstates @xcite .
the differential rates in decay time and angular variables for the decay @xmath1 are given in the references @xcite .
the time - dependent angular analysis of flavour tagged @xmath1 decays also needs to take into account the experimental effects such as background contamination , detector resolution and reconstruction efficiency .
the decay @xmath1 has been extensively studied at the tevatron and lhc experiments @xcite .
early study at cdf and d0 experiments each using an integrated luminosity of 2.8 fb@xmath38 showed a @xmath39 deviation from their sm expectations ( fig .
[ fig : tevatron_early ] ) @xcite .
however , this was not confirmed by the cdf updated result using 5.2 fb@xmath40 of data @xcite and the d0 updated result using 8.0 fb@xmath38 of data @xcite , nor by the much more precise lhcb result based on 0.37 fb@xmath38 of @xmath41 collision data ( fig .
[ fig : lhcb_early ] ( left ) ) @xcite .
furthermore , following the method described in ref .
@xcite , lhcb used the 0.37 fb@xmath38 sample to measure the phase difference between the s - wave and p - wave amplitudes as a function of the @xmath36 invariant mass for each of the two ambiguous solutions ( see fig .
[ fig : lhcb_early ] ( left ) ) and identified the solution with a decreasing trend as the physical solution ( solution i in fig .
[ fig : lhcb_early ] ( right ) ) .
this determined the sign of @xmath42 to be positive with a 4.7 @xmath43 significance @xcite , and resolved the two - fold ambiguity of @xmath31 for the first time .
the remaining solution of @xmath31 and @xmath42 in the lhcb analysis of @xmath1 decays was consistent with the sm expectations .
the most up - to - date results from the lhcb and cdf experiments will be discussed in details in section [ sec : status ] .
-@xmath42 plane in ref .
@xcite from the combination of early d0 and cdf results each based on 2.8 fb@xmath38 , where @xmath44 .
, scaledwidth=45.0% ] -@xmath42 plane from the lhcb analysis of 0.37 fb@xmath38 @xcite .
( right ) the phase difference between the s - wave and p - wave amplitudes as a function of the @xmath36 invariant mass for each of the two solutions in the @xmath1 analysis @xcite . , title="fig:",scaledwidth=45.0% ] -@xmath42 plane from the lhcb analysis of 0.37 fb@xmath38 @xcite .
( right ) the phase difference between the s - wave and p - wave amplitudes as a function of the @xmath36 invariant mass for each of the two solutions in the @xmath1 analysis @xcite .
, title="fig:",scaledwidth=45.0% ]
recently , lhcb updated its @xmath1 analysis result using 1 fb@xmath38 of @xmath41 collision data collected during the 2011 lhc run at a center of mass energy of @xmath45 tev @xcite .
a clean sample containing about 21,200 @xmath1 signal events in a @xmath36 mass window of 12 mev around the @xmath37 mass peak is selected using the particle identification and kinematic information .
the reconstructed invariant mass distribution of the selected @xmath1 candidates with decay time @xmath46 above 0.3 ps is shown in fig .
[ fig : lhcb_data ] ( left ) , where a @xmath47 mass constraint is applied in the vertex fit .
these events were triggered by requiring a relatively high transverse momentum muon track from the @xmath47 decay to be displaced from the @xmath41 interaction point .
the trigger efficiency depends on the decay time of the @xmath2 mesons .
the geometrical acceptance of the detector and the kinematic requirements on the final state particles also induce a dependence of the reconstruction efficiency as a function of the angular variables .
both efficiency effects are corrected for in the analysis .
the background is dominated by combinatorial events and its decay time and angular model is constructed using @xmath2 mass sidebands .
the decay time resolution effect is modelled using a gaussian model , which has a width @xmath48 . here
@xmath49 is the event - by - event decay time resolution .
the scale factor @xmath50 is estimated to be @xmath51 from a fit to the @xmath52 region ( fig .
[ fig : lhcb_data ] ( right ) ) and allowed to vary within this uncertainty in the fit for extraction of @xmath31 .
this event - by - event resolution model has a statistical power for measurement of mixing - induced @xmath0 asymmetries in @xmath2 decays equivalent to that of a single gaussian model with a constant width of 45 fs
. candidates .
( right ) decay time distribution of @xmath1 candidates with a true @xmath47 including the @xmath52 region and superimposed fit result .
both are from ref .
, title="fig:",scaledwidth=42.0%,height=207 ] candidates .
( right ) decay time distribution of @xmath1 candidates with a true @xmath47 including the @xmath52 region and superimposed fit result .
both are from ref .
, title="fig:",scaledwidth=47.0% ] in this analysis , the flavour of the @xmath53 ( or @xmath54 ) meson at production ( @xmath55 ) is identified using the opposite side ( os ) tagging method , which exploits information about the other @xmath56-hadron from pair production of @xmath57 quarks , including charges of the decay products of the other @xmath56-hadron .
a wrong tag probability of the os tagging decision is estimated for each @xmath53 candidate , and this estimated probability is calibrated in the control channel @xmath58 , as shown in fig .
[ fig : lhcb_tagging ] ( left ) .
the distribution of calibrated os wrong tag probability of the tagged @xmath1 signal candidates is shown in fig .
[ fig : lhcb_tagging ] ( right ) , from which an average wrong tag probability of @xmath59 is obtained .
the tagging efficiency is @xmath60 . the effective tagging efficiency for the @xmath1 sample is estimated to be @xmath61 . ) as a function of the estimated os wrong tag probability ( @xmath62 ) for background subtracted @xmath58 decays .
( right ) distribution of calibrated os wrong tag probability of tagged @xmath1 signal candidates .
both are from ref .
title="fig:",scaledwidth=42.0%,height=234 ] ) as a function of the estimated os wrong tag probability ( @xmath62 ) for background subtracted @xmath58 decays .
( right ) distribution of calibrated os wrong tag probability of tagged @xmath1 signal candidates .
both are from ref .
, title="fig:",scaledwidth=45.0% ] the analysis uses the @xmath2 oscillation frequency @xmath63 @xmath64 @xcite and allows it to float within its uncertainty .
the fit projections on the decay time @xmath46 and the three angular variables are shown in fig .
[ fig : lhcb_fit ] .
the numerical results of the major physics parameters are @xmath65 where @xmath66 is the fraction of s wave contribution in a window of 12 mev around the @xmath37 mass . as can be seen in fig .
[ fig : bcpv : phis ] ( left ) , the measurement of @xmath31 and @xmath42 is in good agreement with the sm predictions .
these results are still dominated by statistical uncertainties .
the important sources of systematic uncertainties include the neglected direct @xmath0 violation , insufficient modelling of angular acceptance and background effects .
a refined lhcb analysis using the same data sample is in progress .
this will include the same side kaon tagging information to increase effective tagging efficiency and also benefit from the improved understanding of the systematic uncertainties .
mev window around the @xmath2 mass peak @xcite . ,
title="fig:",scaledwidth=40.0% ] mev window around the @xmath2 mass peak @xcite . , title="fig:",scaledwidth=40.0% ] mev window around the @xmath2 mass peak @xcite .
, title="fig:",scaledwidth=40.0% ] mev window around the @xmath2 mass peak @xcite .
, title="fig:",scaledwidth=40.0% ] cdf updated its @xmath1 analysis using 9.6 fb@xmath38 of @xmath67 collision data collected at a center of mass energy of @xmath68 tev at the tevatron @xcite .
approximately 11,000 signal decays are selected and analyzed . due to the low decay time resolution ,
the cdf analysis has limited sensitivity to @xmath31 . the cdf @xmath42 result has a precision comparable to that of the lhcb result : @xmath69 the latest hfag @xcite average of the results from the lhcb @xcite , cdf @xcite and d0 @xcite analyses is shown in fig .
[ fig : bcpv : phis ] ( right ) .
the lhcb result dominates the combination , which is in good agreement with the sm predictions .
( at the time of writing this article , the atlas experiment has also reported the result of a time - dependent angular analysis of @xmath70 decays without flavour tagging @xcite .
we do not discuss this result here . ) and @xmath42 from @xmath70 decays using 1.0 fb@xmath38 @xcite .
( right ) hfag 2012 combination of @xmath31 and @xmath42 results , where the 1 @xmath43 confidence region is shown for each experiment and the combined result @xcite .
[ fig : bcpv : phis ] , title="fig:",scaledwidth=51.0% ] and @xmath42 from @xmath70 decays using 1.0 fb@xmath38 @xcite .
( right ) hfag 2012 combination of @xmath31 and @xmath42 results , where the 1 @xmath43 confidence region is shown for each experiment and the combined result @xcite .
[ fig : bcpv : phis ] , title="fig:",scaledwidth=44.0% ] in the context of model - independent analysis , the new physics contribution to @xmath8 can be parameterized using the complex number @xmath71 , @xmath72 the constraints on @xmath71 provided by the current measurements of @xmath31 , @xmath73 , @xmath74 , @xmath42 and semileptonic asymmetries , are shown in fig .
[ fig : bcpv : newphysics ] @xcite . as can be seen ,
the major constraints on new physics in @xmath8 come from the measurements of @xmath31 and @xmath75 .
no significant new physics contribution is identified and the picture of @xmath2 mixing is sm - like . however , up to about 30@xmath76 new physics contribution in @xmath8 is still allowed at 3@xmath43 confidence level , and probing new physics in @xmath2 mixing at this level requires to improve substantially the measurement precision of @xmath31 .
the lhcb experiment is expected to collect 5 fb@xmath38 of data before 2018 and 50 fb@xmath38 after its upgrade .
this will enable lhcb to push down the uncertainty of @xmath31 to @xmath77 rad around 2018 , and eventually achieve a precision of @xmath78 rad after the upgrade @xcite . .
the coloured areas represent regions with cl @xmath79 for the individual constraints .
the red area shows the region with cl @xmath79 for the combined fit , with the two additional contours delimiting the regions with cl @xmath80 and cl @xmath81 .
[ fig : bcpv : newphysics ] , scaledwidth=48.0% ]
in summary , the study of @xmath0 violation in @xmath1 offers a great opportunity to search for physics beyond the sm that enters the @xmath2 mixing process .
significant progress has been made in the measurement of @xmath31 in @xmath1 , particularly by the lhcb experiment , that allows to put stringent constraints on new physics contribution in @xmath2 mixing .
the lhcb experiment aims to greatly improve the @xmath31 measurement precision for probing sub - leading level new physics contribution in @xmath2 mixing . | study of @xmath0 violation in the decay channel @xmath1 is essential to exploring and constraining physics beyond the standard model in the quark flavour sector .
the experimental progress in this area of activity at the lhc and tevatron is discussed . |
A Michigan man has admitted to police, and at least one victim, that he intentionally infected sex partners with the HIV virus. WOOD's Leon Hendrix reports.
Updated at 4:50 p.m. ET: David Dean Smith's attorney, Richard E. Zambon of Grand Rapids, tells msnbc.com that he plans on "exploring all options" in defending Smith, saying specifically that "I am concerned about his mental health."
Zambon said he hadn't yet seen all of the police and medical records in the case and couldn't talk about specifics, but he said the law under which Smith was charged is a "relatively new statute with not many cases having interpreted" it, meaning few court precedents have been established.
Original post: A Michigan man has been charged with felony sex offenses after he told police he was HIV-positive and had set out to intentionally infect as many people as he could, police said. Health officials have issued an alert warning that "possibly hundreds of people have been exposed to HIV."
The man, identified as David Dean Smith, 51, of Comstock Park, north of Grand Rapids, was arraigned Wednesday on a second count of "AIDS-sexual penetration with an uninformed partner" after police said they had identified a second possible victim.
Smith was initially charged with one count after he went to Grand Rapids police last week and said he had intentionally had unprotected sex with as many people as he could over the last three years, according to police.
According to documents on file with Grand Rapids 61st District Court, Smith claimed to have had sex with "thousands" of partners, intending to kill them by infecting them with HIV. Some of those people are from outside the Grand Rapids area, including people Smith met over the Internet, he told police, according to documents.
Smith faces separate preliminary hearings on the two charges on Jan. 4 and Jan. 9. He remains in the Kent County Jail in lieu of $100,000 bond. Smith's attorney did not immediately reply to requests for comment.
The Kent County Health Department issued an alert Tuesday warning that "hundreds of people may have been exposed to HIV," urging potential victims to come forward and encouraging everyone who may have concerns to be tested for HIV.
Vitals: AIDS discovery could put virus on the run, bioethicist says
One of the two possible victims police say they have found so far said in an interview with NBC station WOOD-TV of Grand Rapids that she was diagnosed with HIV in October 2008.
The woman, whom authorities and NBC News are not identifying, said she knew immediately that it was Smith — whom she said she met through an ad on the Yahoo! Personals website — who had infected her. She called him "a predator" and "a sociopath."
The woman said Smith sent her a text message letting her know that he was going to surrender to police. The message read: "Turning myself into the law, my life is over. Take care. Always love you."
"It's something he should have done years ago," she said. "He shouldn't get a pat on the head for what he did."
Smith said at his arraignment Wednesday that he has been undergoing counseling. Court documents show that Smith was admitted to Pine Rest Christian Mental Health Services recently because he was "suicidal" and had tried to kill himself at least once.
The records say the hospital determined that Smith is "sexually aroused by causing pain to females."
A Facebook page with Smith's name, address and pictures says he graduated from Harry Hill High School in Lansing in 1978 and studied at the University of Phoenix, a for-profit online institution. It shows that he has worked in telecommunications for several companies.
Posts to the account stopped on Nov. 30. Before then, the account owner posted some messages that could possibly be interpreted as alluding to his situation.
"Someone special to me asked me a question about scandulous people, this was my thought," he wrote on Nov. 5. "Let me know what ya think. When you are young you believe people will love you like you want and keep an eye out for those scandulous people...as you get older you realize most everyone is scandulous so you dont trust anyone but keep an eye out for the special ones that truley care."
A day earlier, this message appeared:
"I pray for blessings to all I know, for forgiveness for my shortcommings to them and that they may no peace. And last, that I love them all as much as I can."
Vitals: Double whammy of setbacks cripple war on AIDS
The woman who spoke to WOOD said she had no doubt that there are many other victims. She said Smith told her that he had had sex with as many as 3,000 people, including men as well as women.
"He hits drifters," she said in the interview. "He hits people who are young. He hits young women, and from what I understand, he hits men, too. Those are his targets."
Dani Carlson and Leon Hendrix of NBC station WOOD of Grand Rapids, Mich., contributed to this report. Follow M. Alex Johnson on Twitter and Facebook
More content from msnbc.com and NBC News: ||||| GRAND RAPIDS, Mich. (WOOD) - Police are currently aware of the identity of only one of the victims who they say a man intentionally infected with HIV.
"He's charming," the alleged victim -- who didn't want to be identified -- said of suspect David Smith, "He's very charming."
Smith, 51, was arrested last week after he went to police. Authorities said Smith told them that he intentionally had sex with as many people as he could over the past three years. He said his plan was to infect them with HIV, which was meant to kill them, court records show.
The victim 24 Hour News 8 spoke with is the only victim that Smith has been charged with infecting so far.
When asked what she thought about the fact that Smith turned himself in to police, she said, "It's something he should have done years ago. He shouldn't get a pat on the head for what he did."
"I was diagnosed (with HIV) October 18, 2008," the alleged victim said. "It's hard, though. It's really hard, but support is key and getting the right treatment is key."
She also said she wasn't surprised by the fact that he went to police. "He has this way of being the hero in the beginning. Like he's the problem solver, the hero, he's doing the right thing," she said. "Then something horrible will happen and then he's the victim. So this is probably his 'victim song.'"
Smith told police there are "thousands" of victims. His alleged victim said she believes that claim, calling him "a predator" and "a sociopath."
Investigators allege that Smith had sex with the woman who spoke to 24 Hour News 8 and didn't inform her of his HIV status between early June and mid-October of 2008.
24 Hour News 8 found Smith's Facebook page Tuesday night. It showed posts dating back to September of this year. One post said, in part:
"When you are young you believe people will love you like you want and keep an eye out for those scandulous people...as you get older you realize most everyone is scandulous so you don't trust anyone but keep an eye out for the special ones that truley care." (sic)
The alleged victim said she has no doubt that there are many other victims. She said Smith told her there were 3,000 victims and that they included men and women.
"He hits drifters," said the alleged victim. "He hits people who are young. He hits young women, and from what I understand, he hits men too. Those are his targets."
The alleged victim said she met Smith online through the Yahoo! Personals website.
Police said Smith may have made contact with people outside of Kent County over the Internet. Kent County Health Department officials said they have sent out a statewide alert to get the word out to victims outside of Kent County.
The alleged victim told us she hopes what happened to her encourages others to be cautious when meeting people online, especially if the relationship becomes sexual.
"I thought he was everything in the world I ever wanted or thought I couldn't have," she said. "Put on a condom and it can save the rest of your life. It's one of those things that's worth waiting for."
Kent County Health Department Communications and Marketing Manager Lisa LaPlante said this is the first time the Health Department has seen someone deliberately trying to spread the virus to so many people and that officials are concerned.
"We want to make sure that anyone who may have injected drugs with [Smith], who may have had sex with him, does come forward and get tested," said LaPlante. "We want to make sure that they're not spreading the virus to anyone else."
LaPlante said they don't know how many potential victims are out there, but they want to spread the word and cover all the bases.
"The rate of transmission is relatively low for a single incident, however, that said, it's still there," said LaPlante. "We just want to make sure that if anyone is engaging in any risky behaviors that they're able to find out what their status is."
LaPlante pointed out new HIV diagnoses in Kent County have been down over the past five years. According to information from the Michigan Department of Community Health, the last time yearly HIV diagnoses topped 60 cases in a year was 1991.
24 people were diagnosed with HIV and 18 were diagnosed with AIDS in Kent County through October 2011. 37 were diagnosed with HIV and 25 were diagnosed with AIDS in 2010.
The Kent County Health Department offers free, anonymous and confidential testing. LaPlante said it's important to get tested if there's a chance you could have been exposed, even if you don't have symptoms.
"In some cases it can take 8 to 10 years before people realize that they have the virus. But it can start showing up in the system within a matter of six months and that's why people should get tested more than once in the time period after which they've been exposed to it," said LaPlante.
Counselors are on hand at the Kent County Health Department as HIV tests are administered to offer advice on safe sex | – Awful story out of Michigan: Authorities say a 51-year-old man who is HIV-positive confessed to intentionally exposing hundreds of people to the disease through unprotected sex, report MSNBC and the Grand Rapids Press. Court documents say that David Dean Smith harbored a "desire to harm women" and tried to infect as many people as he could. Police have identified two victims so far, and Smith faces felony charges of not informing them about his condition before having sex. One of the women said she met Smith online and was diagnosed with HIV in 2008. "He hits drifters," she tells WOOD-TV. "He hits people who are young. He hits young women, and from what I understand, he hits men, too. Those are his targets." She said he claimed to have slept with 3,000. |
sufficient mass accumulation in a confined space forms a black hole . due to the stability of the minkowski spacetime , sufficiently small initial data will remain small in time evolution .
both scenarios were explored analytically by christodoulou @xcite , for which he considered minimally coupled massless scalar fields in spherical symmetry , and established various fundamental theorems . using the same model , choptuik investigated the threshold of black hole formation by numerical means @xcite , and demonstrated that the scalar wave either collapses to a black hole or disperses to infinity , with a critical solution separating them .
universality and self - similarity of the critical solution and power scaling laws of the black hole masses were identified , which have now fallen under the name `` critical phenomena '' ( see , e.g. , review articles @xcite ) . since choptuik s breakthrough , critical phenomena
have been extended to many other matter fields . particularly for
minimally coupled scalar fields with potentials , they have been observed in quadratic potentials @xmath6 ( massive scalar ) @xcite and symmetrical double - well potentials @xcite . besides the numerical approach
, attempts have been made to explore the possibility of constructing exact solutions that exhibits critical behaviors in the einstein - scalar theory .
unfortunately , such solutions seem quite rare and difficult to find .
perhaps the most well - known example is roberts one - parameter self - similar solution @xcite , which has been analysed for different parameter regimes @xcite and used as a toy model for critical collapse .
the wyman solution has also been argued to exhibit a type of critical behavior @xcite , even though it is static and has no significant relevance to gravitational collapse .
very recently , a one - parameter family of exact time - dependent spherically symmetric solutions were discovered in four - dimensional einstein gravity minimally coupled to a dilaton scalar field with a self - interaction potential @xcite . for a certain range of the parameter ,
the solution represents gravitational collapse to a static scalar - hairy black hole in an ( a)ds or minkowski background .
the solution also reduces to the roberts solution in an appropriate limit , and therefore a connection to critical collapse was suspected . in this paper
, we will show that this suspicion is justified .
the paper is organized as follows . in the next section
, we will first present the time - dependent solution along with its scalar invariants , the energy - momentum tensor and masses .
the energy conditions and the relation to the roberts solution are also discussed . in section [ sec_crit ]
, we move on to details of critical behaviors in three distinct parameter regimes : the subcritical , critical and supercritical .
we use the misner - sharp mass to identify the apparent horizon , the causal nature of the central singularity and the black hole mass .
additionally , we analyze outgoing radial null geodesics and draw the penrose diagrams for each regime
. then the paper is concluded in section [ sec_conc ] .
in this section , we consider the minimally coupled einstein - scalar field with a scalar potential .
the lagrangian density takes the form @xmath7 , \label{l } \\
v(\phi ) & = & 4\lambda \left[3\sinh\phi - \phi(\cosh\phi + 2)\right ] , \label{v}\end{aligned}\ ] ] where @xmath8 is a real - valued scalar field and @xmath9 its potential with a coupling constant @xmath10 .
this particular potential function was due to zloshchastiev @xcite ( see also @xcite ) , for which we have removed terms that contributes to a nonzero cosmological constant such that @xmath11 .
the potential has an odd parity and a taylor expansion @xmath12 at the origin which accounts for a quintic interaction in the leading order term .
the mass of the scalar field is defined as @xmath13 .
hence we are dealing with a self - coupled nonlinear massless scalar field .
moreover , the potential is strictly monotonic and unbounded from below ( asymptotically , @xmath14 for @xmath15 ) .
therefore various established no - hair theorems for minimally coupled scalar fields can be bypassed ( see , e.g. , @xcite ) . given by ( [ v ] ) with @xmath16 .
[ vphi],scaledwidth=50.0% ] from the lagrangian density ( [ l ] ) , the energy - momentum tensor for the scalar field is @xmath17 g_{\mu\nu}.\ ] ] the einstein equations ( @xmath18 ) and the klein - gordon equation can be written as @xmath19 to construct time - dependent solutions , we have followed the newman - penrose formalism and further extended a generalized form of the robinson - trautman solution @xcite for nonlinear scalar fields . in eddington - finkelstein - like coordinates , the resulting metric @xcite is given by @xmath20 where @xmath21 is an advanced time and the area radius @xmath22 is not to be confused with the ricci scalar @xmath23 .
the solution contains one free real parameter @xmath0 , commonly known as the scalar charge . for the newman - penrose formalism
, one can pick the following the null tetrad : @xmath24 with the complex coordinate @xmath25 .
accordingly , the only non - vanishing weyl scalar is @xmath26 thereby the spacetime is of the petrov type d , and it possesses two congruences of null geodesics along the double principal null directions @xmath27 and @xmath28 , both being shearfree and non - twisting
. the ricci scalar is @xmath29 .
\label{ricci}\end{aligned}\ ] ] both quantities indicate a curvature singularity at the center @xmath30 and that the metric is asymptotically flat as @xmath31 .
to study the global structure , it is preferable to use the area radius @xmath22 for coordinates ( though we will still perform certain calculations with the @xmath32-coordinates for simplicity ) .
thus with @xmath33 we can transform the metric into a standard form for spherically symmetric spacetimes : @xmath34 where the function @xmath35 is the misner - sharp quasi - local mass which one may interpret as the gravitational mass inside a sphere of the area radius @xmath22 at an advanced time @xmath21 .
this mass function reduces to the bondi - sachs ( bs ) and adm masses in appropriate limits @xcite . specifically , one has @xmath36 which measures the mass on null hypersurfaces of constant @xmath21 .
similarly , the adm mass is @xmath37 which represents the conserved total mass of the scalar field . to ensure the positivity of the asymptotic masses ,
one should at least require @xmath38 .
without loss of generality , we only consider @xmath39 and @xmath40 from now on .
the case for @xmath41 and @xmath42 can be equally obtained by mapping @xmath43 , @xmath44 and @xmath45 which leaves @xmath46 , the equations of motion and the metric ( [ metricr ] ) invariant . in terms of the coordinate @xmath22 , the ricci scalar , as a curvature invariant , can be calculated by directly plugging ( [ rr ] ) into ( [ ricci ] ) .
particularly near @xmath47 , we have @xmath48 expressions for the energy - momentum tensor are , unfortunately , too cumbersome to be fully exhibited here : @xmath49 we make a note that all listed components above become singular at @xmath50 ( analogous to @xmath51 of the vaidya solution @xcite ) and that the only non - vanishing component at @xmath47 is @xmath52 .
the energy - momentum tensor ( [ t ] ) for minimally coupled scalar fields with potentials always satisfies the null energy condition .
additionally , since @xmath53 , it satisfies the strong energy condition as well @xcite .
however , the weak energy conditions can be violated locally in the spacetime , depending on the parameters @xmath10 and @xmath0 .
but we can show that it is fulfilled for large @xmath54 in the static limit ( see appendix [ app_a ] ) .
furthermore , the solution we have described so far is closely related to the roberts solution @xcite for linear scalar fields without self - interaction potentials . to recover the latter , one only needs to reparameterize @xmath55 and take @xmath56 such that @xmath46 vanishes and the metric ( [ metricr ] ) becomes @xmath57 thereby we may follow roberts example @xcite in discussing various global aspects of our solution . comparisons between the two may also benefit our discussion . in this regard
, we recall that the black hole mass of the roberts solution grows to infinity as @xmath58 ( to see this , perform the aforementioned limit in ( [ madm ] ) ) .
this undesirable property is clearly avoided in our solution on account of the extra @xmath46 .
given that the quantities @xmath59 , @xmath60 and @xmath61 , as well as the scalar field @xmath8 , all vanish at @xmath47 , we can match the spacetime continuously across the null hypersurface @xmath47 with a minkowski spacetime for @xmath62 .
thus we consider incoming flux of the scalar wave to be turned on at the advanced time @xmath47 . by doing so
, we also exclude the region where the bondi - sachs mass becomes negative ( cf .
( [ mbs ] ) with @xmath63 ) .
as @xmath58 , we have @xmath64 and the solution ( [ metricr ] ) ( also ( [ metricr ] ) ) reaches a static limit . with the time - dependence fading away ,
we can rewrite the resulting metric in a schwarzschild - like form @xcite : @xmath65 where we have adopted @xmath66 . to reinstate the area radius @xmath22
, one can resort to @xmath67 analogous to the wyman solution @xcite , the static solution itself also demonstrates a `` phase transition '' at the special value @xmath68 . a first clue for this is to look at the outgoing null geodesics emanated from the center : @xmath69 which indicates that the singularity is completely censored ( no light emitted ) if @xmath70 , but ( at least ) locally naked if @xmath71 .
this relates to the fact that the central singularity is covered by an event horizon only when @xmath70 @xcite .
similarly for the dynamical solution , the existence of an apparent horizon also relies on the sign of @xmath72 .
the apparent horizon is determined by the root of @xmath73 . for a given @xmath74 ( also recall @xmath39 , @xmath40 ) , the metric function @xmath75 is strictly increasing from @xmath72 to @xmath76 as @xmath22 goes from @xmath77 to @xmath78 . hence
a unique apparent horizon exists iff @xmath70 .
furthermore , the criticality of @xmath68 also presents itself in the misner - sharp mass function : @xmath79 the sign of @xmath80 above implies that the central singularity is timelike and untrapped for @xmath81 , and spacelike and trapped for @xmath82 @xcite .
typical graphs of the mass function in the static limit are given in fig .
[ fig_ms1 ] . from the plot
, one can see that the mass function is typically increasing for large @xmath22 .
but for @xmath82 , it can be decreasing immediately outside the event horizon , which indicates a local breakdown of the dominant energy condition @xcite . in the static limit @xmath58 and with @xmath16 .
the critical case corresponds to @xmath83 .
event horizons are located at intersections with @xmath84.,scaledwidth=60.0% ] depending on the value of the parameter @xmath0 , we can now classify the time - dependent solution into three different types , i.e. , the subcritical ( @xmath85 ) , critical ( @xmath68 ) and supercritical ( @xmath82 ) . ( 0,0 ) node[below]@xmath87
node[midway , below=4pt , right=4pt]@xmath88 ( 1,1 ) node[right]@xmath89 node[pos=0.55 , above=4pt , right=4pt]@xmath90 node[midway , below=2pt , sloped , scale=0.8]@xmath91 ( 0,2 ) node[above]@xmath92 ; ( 0,0 ) ( 0,1 ) node[at end , above=4pt , sloped , scale=0.8]@xmath50 ; ( 0.5,0.5 ) ( 0,1 ) node[midway , below , sloped , scale=0.8]@xmath47 ; ( 0,1 ) ( 0,2 ) ; the penrose diagram is given in fig .
[ fig_pen1 ] .
the solution represents a scalar field collapsing from the past null infinity towards the center at @xmath50 .
the gravitational interaction is not strong enough to create a black hole .
however , the wave packet is not dispersing away to infinity after colliding at the center .
instead , it forms a globally naked timelike singularity which has negative mass and becomes static as the time progresses .
this collapse outcome is a major deviation from the subcritical case of the roberts solution and choptuik s numerical examples @xcite .
naked central singularities have also been shown to exist in self - similar collapse of scalar fields @xcite .
( 0,0 ) node[below]@xmath87
node[midway , below=4pt , right=4pt]@xmath88 ( 1,1 ) node[right]@xmath89 node[pos=0.55 , above=4pt , right=4pt]@xmath90 node[midway , below=2pt , sloped , scale=0.8]@xmath91 ( 0.5,1.5 ) node[above]@xmath92 ; ( 0,0 ) ( 0,1 ) node[midway , above=4pt , sloped , scale=0.8]@xmath50 ; ( 0.5,0.5 ) ( 0,1 ) node[midway , below , sloped , scale=0.8]@xmath47 ; ( 0,1 ) ( 0.5,1.5 ) node[midway , above=4pt , sloped , scale=0.8]@xmath50 ; the penrose diagram is shown in fig .
[ fig_pen2 ] , which is qualitatively no different from the critical case of the roberts solution @xcite .
the central singularity is also null due to @xmath94 the mass function vanishes at the singularity ( cf .
( [ mr0 ] ) ) , while the curvature diverges there . in the @xmath32-coordinates ,
the outgoing radial null geodesics obey @xmath95 at the center , we have @xmath96 hence the above geodesic equation has a constant solution @xmath97 ( i.e. , @xmath50 ) . in appendix [ app_b ] , we prove the local uniqueness of this constant solution , which means that no null geodesics initiated at @xmath98 with @xmath99 can ever leave @xmath30 , let alone reaching the null infinity . for outgoing null rays with @xmath100 , they will always reach the null infinity since the function @xmath101 is positive and strictly increasing in both @xmath54 and @xmath21 . in summary
, there is no apparent horizon in the spacetime ; observers can detect signals from an arbitrarily small vicinity ( with arbitrarily large curvature ) of the central singularity , but no direct signals from it until they actually run into the singularity .
hence one may think of this critical spacetime as an intermediate state between a naked singularity and a black hole .
it is normally expected that critical solutions in scalar field collapse may possess self - similarity , e.g. , the roberts solution . however , in appendix [ app_c ] , we show that self - similarity ( homothety ) is in fact missing from our solution , not only for the critical case , but for all @xmath40 .
( 0,0 ) node[below]@xmath87
node[midway , below=4pt , right=4pt]@xmath88 ( 1,1 ) node[right]@xmath89 node[pos=0.55 , above=6pt , right]@xmath90 node[midway , below=2pt , sloped , scale=0.8]@xmath91 ( 0.75,1.25 ) node[above]@xmath92 ; ( 0,0 ) ( 0,1.25 ) node[midway , above=4pt , sloped , scale=0.8]@xmath50 ; ( 0.625,0.625 ) ( 0,1.25 ) node[pos=0.2 , below , sloped , scale=0.8]@xmath47 ; ( 0,1.25 )
( 0.75,1.25 ) node[midway , above=4pt , scale=0.8]@xmath50 ; ( 0,0.5 ) ( 0.75,1.25 ) node[pos=0.35 , above , sloped , scale=0.8]eh ; ( 0,1.25 ) .. controls ( 0.45,0.9 ) and ( 0.625,1.125 ) .. ( 0.75,1.25 ) node[pos=0.4 , above , scale=0.8]ah ; with @xmath16 and @xmath103 . as
@xmath21 grows , the curve reaches a plateau that corresponds to the event horizon . , scaledwidth=50.0% ] this case captures strong - field collapse of the scalar field .
[ fig_pen3 ] shows the global structure of the spacetime .
the central singularity at @xmath104 is now spacelike , completely censored and surrounded by an apparent horizon . as mentioned before
, one needs to solve @xmath105 for @xmath106 to determine the location of the apparent horizon as a function of @xmath21 .
this can be done numerically , and in fig .
[ fig_ah ] , we give an example of @xmath107 plotted with maple 16 ( ` implicitplot ` ) . as a consequence of the null energy condition , the spacelike apparent horizon @xmath108 should be monotonically increasing in @xmath21 @xcite and tend to a finite value as it approaches the event horizon from the inside .
this is indeed confirmed by the numerical plot , as well as all other samples tested by us with various inputs of @xmath0 . by definition ,
the event horizon is always null . to locate the event horizon
, one needs to look for outgoing radial null geodesics that are not able to reach infinity by propagating them from the center of the spacetime .
preferably , this can be done through numerical integration , since analytical solutions are very unlikely to obtain .
as one may expect , the event horizon extends beyond the null hypersurface @xmath47 into the initial flat region , which means that it comes to exist before the central singularity starts to form .
this is a teleological feature also seen in the vaidya spacetime .
moreover , in the limit @xmath58 , the event horizon of the dynamical black hole will match the static one ( cf .
( [ static ] ) ) . in dynamical spacetimes ,
a black hole can be locally defined by its apparent horizon .
thereby one can evaluate the misner - sharp mass on the apparent horizon as a measure of the mass of a dynamical black hole , i.e. , @xmath109 . following this definition , in order to obtain the final mass of the black hole , one needs to take the limit @xmath58 : @xmath110 here the final area radius of the black hole , denoted by @xmath111 , is determined by @xmath112 now consider the near - critical regime with @xmath113 .
for a small @xmath111 , the right - hand side of the above equation has the following generalized series expansion : @xmath114 ignoring higher order terms , we obtain an approximate scaling law for the black hole mass : @xmath115 this product - logarithmic relation ( lambert @xmath116-function ) is significantly different from the power law of choptuik .
in addition , by a similar argument for small @xmath74 , we have also determined that the initial growth of the black hole mass follows @xmath117 which resembles the power law of the roberts solution for having the same exponent @xmath118 .
the basic physical picture we have drawn so far is the following : an imploding scalar wave packet , with the spherical wave front ( located at the advanced time @xmath47 ) travelling inward at the speed of light , collides at the center of the 3-dimensional physical space . depending on the strength of the wave packet , it either forms a globally naked singularity in weak - field collapse , or a hairy black hole in strong - field collapse . in case of the latter , the formation of black holes always starts with zero mass . in both cases , the spacetime is becoming static as the collapse reaches its ending .
meanwhile , the total mass stays finite .
there also exists a critical case interpolating between these two dominant outcomes , of which the spacetime is sitting on the verge of containing a naked singularity or a black hole , but just avoiding both .
the phenomenology of our model has unusual features , but it still fits into the basic picture of critical collapse .
major deviations from previously known examples of critical phenomena are at least threefold : 1 ) the presence of naked singularities as the endstate of weak - field collapse instead of dispersal to infinity , 2 ) the absence of self - similarity in the critical case , 3 ) the product - logarithmic scaling law of the black hole mass in contrast to the usual power law .
all these features may be attributed to the unbounded negative scalar potential . with
the black hole mass being kept finite , our solution can also be considered as a `` regularized '' generalization of the roberts solution which has been thought unfavorable for not having an event horizon . for future work , we point out that more is yet to be understood regarding the legitimacy and universality of the `` critical solution '' with @xmath68 .
the stability of the solution also raises important questions .
furthermore , our earlier paper @xcite also includes ds and ads generalizations of the solution ( [ metricr ] ) .
it is expected that the local picture of the naked singularity / black hole formation may not be affected by the introduction of an effective cosmological constant , at least when the constant is small .
nonetheless , the global structures will be quite different .
perhaps more interestingly , the singularity / black hole `` phase transition '' in the ads background may be further examined in the context of the ads / cft correspondence .
without loss of generality , we consider a normalized timelike geodesic vector field @xmath119 such that @xmath120 and @xmath121 .
the weak energy condition can be expressed as @xmath122 with @xmath123 .
the inequality holds true if the sum of the last two terms above is non - negative .
given the solution ( [ metricr ] ) , we can estimate them as follows : @xmath124\frac{q^2}{2r^4 } + \mathcal{o}(r^{-5}),\end{aligned}\ ] ] where the second equality stands for a series expansion at @xmath125 .
now consider the static limit @xmath58 in which case the ( negative ) leading term vanishes .
the sum is thus dominated by @xmath126 for large @xmath54 .
so the weak energy condition at least holds in this situation .
another noteworthy situation is to consider a small neighborhood of the center @xmath30 , where we have @xmath127 the leading term indicates that for @xmath74 and @xmath85 , the weak energy condition is satisfied near the timelike central singularity in subcritical evolutions .
in this section , we prove the ( local ) uniqueness of the constant solution @xmath97 for the null geodesic equation ( [ geo ] ) .
because @xmath128 blows up at @xmath30 , the picard - lindelf theorem fails to apply .
instead we will use the comparison theorem ( generalized gronwall s inequality ) for nonlinear first - order odes ( @xcite , see 9 ) . now consider a `` backward '' initial value problem ( ivp ) : @xmath129 where @xmath130 , given by ( [ h ] ) , is non - negative .
all we need to show is that the solution to this ivp can never reach @xmath30 with @xmath131 , i.e. , @xmath132 . for the critical case @xmath133 , the right - hand side of the equation
is bounded above by @xmath134 with @xmath135 .
here we have used the fact that the function @xmath136 is monotonically increasing in @xmath21 .
the bounding differential equation @xmath137 can be solved analytically and the general solution is @xmath138 with an integration constant @xmath139 . particularly for the initial condition @xmath140 , the constant @xmath139 can be determined as @xmath141 so that we have @xmath142 .
then by the virtue of the comparison theorem , the solution of ( [ ivp ] ) is bounded below by @xmath143 this completes the proof .
in this section , we show that the dynamical solution ( [ metricr ] ) is not self - similar , i.e. , that it does not admit a homothetic killing vector @xmath144 satisfying @xmath145 with @xmath146 a non - zero real constant . to see this , we first write down explicitly components of the above equation : @xmath147 note that the first two equations imply that @xmath148 , which , when combined with ( [ ke4 ] ) , yields @xmath149 then again from ( [ ke4 ] ) , one obtains @xmath150 .
plugging them back in ( [ ke2 ] ) gives one @xmath151 which fails to hold if @xmath152 .
therefore we conclude that a homothetic vector does not exist for our solution .
we are grateful to xinliang an , daniel finley and tong - jie zhang for useful discussions and kind assistance .
we thank for the questions and comments from anonymous referees of our paper @xcite , which this follow - up paper is intended to address .
the work is funded by china postdoctoral science foundation and in part by the nsfc grants 11175269 and 11235003 .
d. christodoulou , commun .
phys . * 105 * , 337 ( 1986 ) ; _ ibid_. * 106 * , 587 ( 1986 ) ; _ ibid_. * 109 * , 591 ( 1987 ) ; _ ibid_. * 109 * , 613 ( 1987 ) ; commun .
pure appl .
xliv , 339 ( 1991 ) ; ann . math . * 140 * , 607 ( 1994 ) ; _ ibid_. * 149 * , 183 ( 1999 ) . j.d
. bekenstein , _ transcendence of the law of baryon - number conservation in black - hole physics _
rev . lett . * 28 * , 452 ( 1972 ) ; _ ibid_. _ nonexistence of baryon number for black holes .
ii _ phys .
d * 5 * , 2403 ( 1972 ) . | we examine a one - parameter family of analytical solutions representing spherically symmetric collapse of a nonlinear massless scalar field with self - interaction in an asymptotically flat spacetime .
the time evolution exhibits a type of critical behavior . depending on the scalar charge parameter @xmath0 as compared to a critical value @xmath1 , the incoming scalar wave collapses either to a globally naked central singularity if @xmath2 ( weak field ) or to a scalar - hairy black hole if @xmath3 ( strong field ) , both having finite asymptotic masses . near the critical evolution
, the black hole mass follows a product - logarithmic scaling law : @xmath4 with @xmath5 and @xmath3 .
the solution admits no self - similarity and satisfies the null and the strong energy conditions . |
10 p. arnold , g. d. moore and l. g. yaffe , jhep * 0111 * , 057 ( 2001 ) ; jhep * 0112 * , 009 ( 2001 ) ; jhep * 0206 * , 030 ( 2002 ) .
k. j. eskola , h. honkanen , h. niemi , p. v. ruuskanen and s. s. rsnen , phys .
c * 72 * , 044904 ( 2005 ) .
k. j. eskola , k. kajantie , p. v. ruuskanen and k. tuominen , nucl .
b * 570 * ( 2000 ) 379 .
g. y. qin , j. ruppert , s. turbide , c. gale , c. nonaka and s. a. bass , arxiv:0705.2575 [ hep - ph ] . | the nuclear modification factor @xmath0 for charged hadron production at the lhc is predicted from jet energy loss induced by gluon bremsstrahlung .
the arnold , moore , and yaffe @xcite formalism is used , together with an ideal hydrodynamical model @xcite .
we present a calculation of the nuclear modification factor @xmath0 for charged hadron production as a function of @xmath1 in pb+pb collisions at @xmath2 in central collisions at mid - rapidity at the lhc .
the net - energy loss of the partonic jets is calculated by applying the arnold , moore , and yaffe ( amy ) formalism to calculate gluon bremsstrahlung @xcite .
the details of jet suppression relies on an understanding of the nuclear medium , namely the temperatures and flow profiles that are experienced by partonic jets while they interact with partonic matter at @xmath3 .
our predictions use a boost - invariant ideal hydrodynamic model with initial conditions calculated from perturbative qcd + saturation @xcite .
it is emphasized that the reliability of this work hinges on the validity of hydrodynamics at the lhc .
it has been verified that @xmath0 for @xmath4 production as a function of @xmath1 as obtained in the same boost - invariant ideal hydrodynamical model adjusted to au+au collisions at @xmath5 @xcite is in agreement with preliminary data from phenix in central collisions at rhic ( and the result is very close to the one obtained in 3d hydrodynamics presented in @xcite ) . in amy
the strong coupling constant @xmath6 is a direct measure of the interaction strength between the jet and the thermalized soft medium and is the only quantity not uniquely determined in the model , once the temperature and flow evolution is fixed by the initial conditions and subsequent hydrodynamical expansion .
we found that assuming a constant @xmath7 describes the experimental data in most central collisions at rhic .
it is conjectured that @xmath6 should not be changed very much at the lhc since the initial temperature is about twice larger than the one at rhic whereas @xmath6 is only logarithmically dependent on temperature .
we present results for @xmath8 .
for details of the calculation of nuclear suppression , we refer the reader to @xcite .
the extension to the lhc once the medium evolution and @xmath6 are fixed is straightforward .
the initial jets are produced with an initial momentum distribution of jets computed from pqcd in the factorization formalism including nuclear shadowing effects .
the probability density @xmath9 of finding a hard jet at the transverse position @xmath10 in central a+b collisions is given by the normalized product of the nuclear thickness functions , @xmath11 and is calculated for pb+pb collisions .
the evolution of the jet momentum distribution @xmath12 in the medium is calculated by solving a set of coupled rate equations with the following generic form , @xmath13,\end{aligned}\ ] ] where @xmath14 is the transition rate for the partonic process @xmath15 which depends on the temperature and flow profiles experienced by the jets traversing the medium .
the hadron spectrum @xmath16 is obtained by the fragmentation of jets after their passing through the medium .
the nuclear modification factor @xmath0 is computed as @xmath17 in fig .
[ raa ] we present a prediction for charged hadron @xmath0 as a function of @xmath1 at mid - rapidity for central collisions at the lhc .
we consider that these two values of @xmath6 define a sensible band of physical parameters .
acknowledgments : we thank the authors of @xcite for providing their hydrodynamical evolution calculation at rhic and lhc energies , t. renk for discussions , and the natural sciences and engineering research council of canada for support . |
the principal constituent of gypsum - based products is calcium sulfate hemihydrate , ( ca so4)h2o .
basically , natural plaster production occurs in four steps , namely , gypsum extraction , calcination preparation , calcination , and selection .
gypsum is a sedimentary rock that is essentially composed of gypsite , anhydrite , and a few impurities , usually clay minerals , calcite , dolomite , and organic matter .
gypsite is a compact material with low hardness and low solubility in water and is the raw material of die .
popularity of type iv gypsum is attributed to its ease of use , relatively quick setting , and reasonable accuracy . a crucial factor in the success of this process is having a model that is both accurate and possesses a smooth surface . in dentistry
dental models are subjected to constant handling , and hence , they must be fracture resistant for safe laboratorial procedures
. the surface properties of the die stone influence its ability to tolerate all type of forces during a restoration .
some present low rugosity , jeopardizing the reproducibility of the impression material ; some fail to adequately reproduce the details present in impression .
plaster type iv is the most commonly material used in working models and as auxiliary in laboratory procedures involving dental prosthesis that comply with the american dental association ( ada ) .
because types iv and v dental stones are used for the fabrication of definitive casts , their dimensional stability is important .
it is , however , a material with some limitations such as low resistance to fracture and abrasion .
areas of interest include improved mechanical strength such as resistance to fracture , surface hardness , and resistance to abrasion , and surface improvements such as surface rugosity , accuracy , and detail reproducibility . to obtain more accurate and durable dental casts , some alternative systems
have been suggested such as die metallization , synthetic die , epoxy resin , polyurethane resin reinforced stone , and electroformed dies .
polyurethanesare high industrial performance polymers that , given the ample choice of reagents available , give origin to a wide range of compounds with different chemical and physical properties .
acording to derrien and sturtz , polyurethane resins are naturally flexible and provide sufficient transverse strength .
polyurethane is a biocompatible material and in dentistry it is used in several fields of expertise , such as in prosthetics and implants studies , where it replaces the bone tissue in in - vitro assays .
considering the need for more accurate and resistant models capable of reproducing prosthetic works with a desirable clinical behavior , this study aims to evaluate the resistance to fracture of polyurethane resin models through diametral compression comparing the results to those of die type iv , as well as to evaluate these materials ability to reproduce the details in the model using surface rugosity analysis .
the following three die materials were assessed [ chart 1 ] : materials used in the assays
exakto - form ( bredent , senden , germany ) polyurethane resindurone ( dentsply , petropolis , brazil ) type iv diefuji rock ( gc europe , leuven , belgium ) type iv die
exakto - form ( bredent , senden , germany ) polyurethane resin durone ( dentsply , petropolis , brazil ) type iv die fuji rock ( gc europe , leuven , belgium ) type iv die with the aid of the software autocad , a matrix was developed in aluminum at the precision workshop poostecltda ( poos de caldas mg ) for the test of diametral compression strength .
this matrix is composed of three threaded parts [ figure 1 ] , whose base holds four equidistant teflon cylinders .
the inferior portion of the base is articulated with the portion holding the teflon cylinders through an m6 allen screw , allowing the unscrewing without transmitting tension to the impression materials .
the body is threaded to the base to restrain the impression material , preventing lateral shifts .
this set is composed of three identical trays , allowing the production of three simultaneous impressions that were left to rest for the time specified for each material and , after pouring the impression materials , resulted in 12 cylindrically - shaped test specimens with dimensions of 12 mm ( length ) and 6 mm ( diameter ) , originating from the same mixture .
source : own elaboration for the surface rugosity test , a matrix was developed in aluminum at poostecltda ( pocos de caldas mg , brazil ) with the aid of the software autocad aiming to facilitate its reproduction in any precision workshop .
design of the matrix for the surface rugosity assay source : own elaboration one aluminum tray for the impression material and another for the aluminum model composed of six equidistant cavities which , following the die materials pouring , gave origin to 6 test specimens with a flat surface of 60 mm width and a convex surface with 50 mm height produced from the same mixure .
the trays were mounted and impression were taken one at a time , previously sealing the teflon tray periphery with lc block - out ( ultradent do brazil so paulo - sp ) photopolymerizable laboratory resin to facilitate the unscrewing of the tray [ figure 3 ] .
the impressions were then taken of the teflon cylinders using the double mixture technique ( light body / putty ) with an addition - reaction silicone polymer elite ( zermack , so paulo , brazil ) .
the light body material was injected with an automixpistol ( zermack , so paulo , brazil ) on the teflon cylinders and on the putty previously handled and activated .
the matrix tray was slowly screwed together to allow the impression material flow through the designed orifices , resulting in higher fidelity in the impression process .
three impressions were obtained resulting from the three trays and left to rest for 1 hour . following that , the set was unscrewed and three molds with four cylindrical cavities ( corresponding to the teflon pins ) were obtained [ figure 4a and b ] .
these impressions were filled with type iv durone and fuji rock die ( vacuum handled following the manufacturer 's instructions , which established a certain powder - water ratio determined with digital scale and graduated syringe ) and exakto - form polyurethane resin ( handled according to the manufacturer 's instructions ) .
the flow of the model material was accomplished with the use of brushes and mechanical vibration .
the polyurethane resin leakage did not require vibration owing to its high fluidity , and it was accomplished with the use of a 20 ml disposable syringe [ figure 5a and b ] .
after the required hardening time , the models were separated from the impressions , resulting in 10 test specimens for each material along with 2 test specimens for disposal .
sequence of the matrix mounting for the diametral compression assay caption : ( a ) aluminum tray ( b ) base of the tray articulated to the te on pins ( c ) threaded base and body ( d ) sealing of the te onperiphery with lc block - out ( ultradent do brasil - sao paulo / sp ) .
source : own elaboration matrix molding for the diametral compression assays caption : ( a ) molding with polyvinyl siloxane leakage on the matrix orifices ( b)mold obtained of the teflon pins source : own elaboration modeling material leakage caption : ( a ) type ivdie ( b ) polyurethane resin source : own elaboration the diametral compression strength assay was conducted according to ada # 25 specifications for dental dies .
dl2000 apparatus ( so jos dos pinhais , sp , brazil ) one at a time and compressed with a 2000 kgf load cell at a constant speed of 1 mm / min until fracture .
dl2000 ( so jos dos pinhais , pr , brazil ) as displacement and strength values .
the tray was mounted on a flat base for preparing the test specimens and the six hemispheres were molded using the double mixture technique with addition - reaction silicone polymer elite ( zermack ) .
the light body was injected with an automixpistol over the hemispheres to accommodate the dense material , which covered the entire tray . with the aid of a glass plate ,
the impression material was submitted to uniform pressure , leading to the leakage of excessive material through the metallic matrix lateral reliefs and mold stabilization until the final setting .
after 1 hour , the aluminum mold was removed and the quality of the addition - reaction silicone polymer model was assessed .
the modeling materials were leaked in the same technique described previously . following the hardening time ,
the models were separated from the impressions and the same method was repeated until 10 test specimens and 2 specimens for disposal were obtained [ figures 68 ] .
matrix molding for the surface rugosity assays caption : ( a ) matrix molding with polyvinyl siloxane ( b ) mold on the hemispheres source : own elaboration modeling material leakage caption : ( a ) type iv die leakage ( b ) polyurethane resin leakage source : own elaboration reading of the convex surfaces of the matrix ( a ) and test specimens ( b ) source : own elaboration for the rugosity test , readings were taken at the convex surface of the test specimens [ figure 6 ] . the surface rugosity ( ra ) was measured with a rugosimeter sj201-p mitutoyo ( kawasaki , kanagawa , japan ) , with a sensitivity of 300 m , speed of 0.5 mm / s , and cut - off of 0.8 mm .
this device has a pick - up motorized needle in the transversal unity that takes the readings and can be moved in the vertical axis to fit the test specimen height and in the horizontal axis to read the surface rugosity .
the test specimens and the matrix with the aluminum mold were strapped with double - sided tape to a base tilted by 14 and the readings were taken one at a time . the device was calibrated with a metallic standard provided by the manufacturer with 2.97 m ra .
five measurements were taken for each test specimen at a point equidistant from the center of the sample and their average was used to represent the surface rugosity .
comparison between impression materials was done using kruskal wallis and dunn 's nonparametric tests because the dataset showed variance heterogeneity that could not be stabilized by transformations .
the rugosity results obtained for the impression materials on the convex surface and for the matrix were submitted to variance analysis at one criterion .
fisher 's least significant difference ( lsd ) and dunnett 's test were used in multiple comparisons .
statistical analysis was done using the statistical package for the social sciences version 20 ( spss inc . ,
chicago , il , usa ) , with the significance level of 5% ( = 0.05 ) .
table 1 shows the descriptive analysis with means and standard deviations of resistance to diametral compression and rugosity of the convex surface of plaster type iv ( duroneand fuji - rock ) and of the modified polyurethane resin ( exakto - form ) .
diametral compression strengthand surface rugosity of plaster type iv , modified polyurethane resin and metallic matrix kruskal
wallis test showed significant difference between the impression materials for the diametral compression strength ( p = 0.002 ) .
dunn 's test showed significantly higher results for the modified polyurethane resin ( exakto - form ) .
type iv dies , which did not significantly differ from each other in terms of diametral compression resistance , showed 34.0% ( durone ) and 42.7% ( fuji rock ) lower results in comparison to exakto - form [ table 1 and graph 1 ] .
column diagram of diametral compression strength averages of plaster type iv and modified polyurethane resin variance analysis showed significant difference ( p < 0.001 ) in surface rugosity depending on material impression or matrix . jointly comparing die type iv ,
modified polyurethane resin , and matrix , fisher 's lsd test showed that the rugosity of the convex surface of the fuji rock was significantly smaller than that found in all other materials ( durone , exakto - form resin , and matrix ) .
the rugosity of the matrix was not significantly different from that of durone or modified polyurethane resin [ table 1 and graph 2 ] .
column diagram of rugosity averages of the convex surface of plaster type iv , modified polyurethane resin , and matrix confirming the fisher 's lsd test results , dunnett 's test showed that only fuji rock type iv die showed significantly lower surface rugosity lower than that found in the matrix when comparing the impression materials with the matrix .
all remaining materials showed no significant difference in surface rugosity in comparison to the matrix .
to obtain an accurate model , both impression and die materials should have positive properties .
casts poured in dental stones should be accurate in every respect , dimensionally stable over time , hard enough to withstand the fabrication process , resistant to the inadvertent abrasions caused by fabrication , and have a surface wettability compatible with the waxing process
. however , gypsum casts show low tensile resistance and are prone to fractures , with a poor reproducibility of details .
the development of synthetic resins allowed the search for alternatives to the use of dies , aiming at improved mechanical resistance and precision , such as the studies conducted by derrien and sturtz , dias et al .
kumar and garg , black , and lillywhite et al . the strong , yet flexible
, properties of polyurethane may be an alternative dental arch model . in one study ,
the dimensional changes for polyurethane resin in comparison with other die materials were statistically insignificant .
in addition , the desired abrasion resistance of polyurethane dies results in a dense and nonabsorbent surface , facilitating easy lift off of patterns .
the results , both by the kruskal wallis test and dunn 's test , showed increased strength by diametrical compression for polyurethane resin exakto - form ( bredent , germany ) with a significant difference over the other tested materials , i.e. , plaster type iv durone ( dentsply , brazil ) and fuji rock ( gc europe , belgium ) , which did not differ significantly from each other . for the surface rugosity study , the design of the matrix considered a design that would facilitate the removal of the test specimen from the mold to avoid compromising the surface reading .
there was no statistically significant difference in the comparisons of surface contour differences between the master tooth - silver and the master tooth george taub epoxy and the master tooth - polyurethane in one study conducted by bloem et al .
authors determined the effect of liquids utilized as die lubricant on the compressive strength and surface hardness of a die stone .
silicone oil and palm oil did not affect both the compressive strength and surface hardness of die stone , whereas slurry water and water decreased both the properties of die stone .
, between durone specimens at 1 hour and at 24 hours ; however , the difference was not significant between 24 hours and 7 days .
the diametral compression tests were conducted 7 days after obtaining the samples ( samples of dry plaster ) .
testing surface roughness , the type iv plaster fuji rock presented the best surface quality , whereas the plaster type iv durone and exacto - form polyurethane resin showed no significant difference in surface roughness in relation to the matrix .
polyvinyl siloxane as an impression material has been considered to be an excellent choice in terms of precision and dimensional stability .
agree that there is no significant change in the die with repeated pourings in the same mold .
however , it shows some disadvantages as polymerization is inhibited by the use of latex gloves during its handling .
thus , the polyvinyl siloxane used for the matrix impression was handled without latex gloves and the same impression was used for several dies .
stress the importance of precision during the handling and dosage of die material with the use of distilled water on the mixture , which can interfere with the resistance and alter the die surface . in 2014 , tavarez et al .
showed that a 20% increase over distilled water recommended that volume does not interfere with compression properties of a die type iv .
, we used mechanical spatulation under vacuum . according to vohra and habib , handling of the polyurethane resin was challenging because the properties of the material are highly sensitive to the manipulation technique .
the material is tacky and sticks to instruments , and has low thixotropy ; therefore , it is necessary that pouring is carried out on maximum vibrations to avoid porosities .
stone has limited transverse strength , which may predispose working casts to fracture when they are removed from impressions . regarding resistance to fracture of plaster type iv , the setting time
should be considered because it interferes with the mechanical behavior of tensile and compression strength .
epoxy resin has four times the transverse strength of dental stone , so working casts of this dental material rarely fracture despite thinner areas .
recently poured models should be stored for at least 45 minutes . here , we defined 60 minutes of rest before removing the test specimens from the impression , which is in accordance with kim et al .
chang et al . showed small differences between different pouring time periods even for repoured casts .
sudhakar et al . , also indicate that the hardness of die stone increased as a function of time .
studies have shown that , the longer the storage time of the die material , the higher resistance to compression , approximately twice the value of that obtained after 1 hour ( wet die samples ) .
the diametral compression assays were carried out 7 days after the obtaining of the samples ( dried die samples ) .
both kruskal wallis and dunn 's tests showed significantly higher diametral compression strength for exakto - form polyurethane resin ( bredent , germany ) in comparison to durone type iv ( dentsply , brazil ) and fuji rock ( gc europe , belgium ) , which did not differ from each other in this aspect .
observed the mean compressive strengths of the various dental stone brands ranging from 26.67 mpa ( durone , 1 hour ) to 65.14 mpa ( fuji rock , 7 days ) .
observed an increase in the diametric tensile strength ( dts ) of snap - stone plaster ( type iv ) from 1 hour to 24 hours .
the results from one study revealed that the storage time before repouring had less effect on the surface roughness than the materials themselves did .
surface rugosity tests showed higher surface quality for fuji rock type iv , whereas duronetype iv and exacto - form polyurethane resin showed no significant difference from the matrix surface rugosity .
contrary to gypsum casts , which can not reproduce details smaller than 20 m due to its crystal structure , polyurethane resin have the ability to reproduce details of up to 12 m , and thus , exakto - form polyurethane resin showed the best performance to reproduce the fine details present in the model .
in this study , we show that the polyurethane resin shows the higher resistance to compression , and the exakto - form polyurethane resin showed better reproducibility of details than fuji rock type iv die
| aim : this work evaluated the mechanical and surface behavior of different die materials .
the studied materials are polyurethane resin exakto - form ( bredent ) , gypsum type iv , fuji rock ep ( gc ) , and durone ( dentsply).materials and methods : two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test . the cylindrical test specimens were submitted to tests of diametral compression strength using a dl2000 universal assay machine , with a load cell of 2000 kgf and constant speed of 1 mm / min connected to the software .
kruskal wallis and dunn 's nonparametric tests were used to analyze the results .
the hemispheres were submitted to the surface rugosity assay using a sj201-p rugosimeter with a sensitivity of 300 m , speed of 0.5 mm / s , and cut - off of 0.8 mm , and the readings were taken on the convex surface of the test specimens and metallic matrix .
results were analyzed using with fisher 's least significant differences test ( lsd ) and dunnett 's test.results:kruskalwallis test showed significant difference between die materials for diametral compression strength ( p = 0.002 ) .
dunn 's test showed significantly higher values for modified polyurethane resin ( exakto - form ) .
the gypsum type iv , which did not significantly differ regarding diametral compression strength , showed 34.0% ( durone ) and 42.7% ( fuji rock ) lower values in comparison to exakto-form.conclusion:within the parameters adopted in this study , it is possible to conclude that exakto - form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity , and , along with the gypsum type iv durone , showed better reproducibility of details relative to the fuji rock . |
regards is a prospective cohort study designed to examine regional and racial influences on stroke mortality .
it oversampled blacks and residents of the southeastern stroke belt region , which includes alabama , arkansas , georgia , kentucky , lousiana , mississippi , north carolina , south carolina , tennessee , and virginia ; the carolinas and georgia have the highest stroke incidence and are sometimes called the stroke buckle.9 briefly , 30 239 participants at least 45 years of age were recruited from a commercially available list of residents using a combination of postal mailings and telephone and enrolled between january 2003 and october 2007 . using a computer - assisted telephone interview ( cati ) ,
trained interviewers obtained demographic information and medical history , and an in - home brief physical examination was conducted 3 to 4 weeks after the telephone interview .
participants are followed by cati every 6 months for suspected incident cves and change in cognitive function .
all participants provided written informed consent . for this report , we excluded participants with prevalent chd at baseline ( self - reported history of myocardial infarction [ mi ] , coronary revascularization procedure , evidence of previous mi on the baseline electrocardiogram [ ecg ] ) ( n=5433 ) , missing follow - up data ( n=489 ) , missing menopause status at baseline ( n=338 ) , and premenopausal women ( n=1031 ) ; 24 123 participants were included .
. suspected chd events were adjudicated by a team of experts following published guidelines.20 for mi , medical records were examined for the presence of signs or symptoms suggestive of ischemia ; a rising and/or falling pattern in cardiac troponin level or creatine phosphokinase
myocardial band level over 6 or more hours with a peak level greater than twice the upper limit of normal ( diagnostic cardiac enzymes ) ; and ecg changes consistent with ischemia or mi , guided by the minnesota code and classified as evolving diagnostic , positive , nonspecific , or not consistent with ischemia.21 definite mis were those with diagnostic enzymes or ecg .
probable mis were those with elevated , but not diagnostic ( ie , equivocal ) , enzymes with a positive , but not diagnostic , ecg ; or , if enzymes were missing , with a positive ecg in the presence of ischemic signs or symptoms . only definite or probable
mis were included in this study . for acute chd death , the medical history , hospital records , autopsy reports , interviews with next of kin or proxies , and death certificate or national death index data were reviewed to adjudicate the cause of death , with definite or probable chd death included in this analysis .
cases were assigned to 2 adjudicators and disagreements were adjudicated by committee , with a >0.80 for the presence of definite or probable mi or definite or probable acute chd death .
primary outcomes were total chd events , consisting of definite or probable chd deaths and nonfatal definite or probable mis , as well as acute chd death and nonfatal mi separately . at baseline ,
women were asked , have you gone through the change of life ? and how old were you at the time of your last menstrual period ? to identify those with surgical menopause , participants were asked , have you ever had an ovary removed ? if they answered
women were also asked , have you ever had a hysterectomy , that is , surgery to remove your uterus or womb ? women were classified as having menopause resulting from bso , with or without hysterectomy ; menopause resulting from hysterectomy alone ; or natural menopause .
women with menopause resulting from bso with or without hysterectomy were defined as such owing to the fact that the ovaries continue to make androgens in postmenopause , even as estrogen production ceases,22 and androgens have been postulated to be influential in atherosclerotic disease in women.23 natural menopause was defined as a last menstrual period occurring 12 months before the interview , in the absence of hysterectomy or bso .
if women had stopped menstruating before hysterectomy or bso , they were defined as being in natural menopause .
age , sex , race , income , education , and smoking status were self - reported .
annual household income was dichotomized at $ 35 000 based on previous analyses in this cohort,24 and education was dichotomized at high school diploma .
smokers were defined as having smoked at least 100 cigarettes in their lifetime and smoking now , even occasionally .
how many times per week do you engage in intense physical activity , enough to work up a sweat ?
data on antihypertensive drugs and statin use were based on self - report and in - home pill bottle review , respectively , and data on estrogen therapy were based on in - home reviews conducted by trained interviewers .
anthropometrics and blood pressure were ascertained during an in - home visit using a standardized protocol ; body mass index ( bmi ) and waist circumference have previously been demonstrated to predict mortality risk independently in regards.25 fasting blood and urine markers included total cholesterol , high - density lipoprotein ( hdl ) cholesterol , glucose , high - sensitivity c - reactive protein ( crp ) , serum creatinine , and urinary albumin and creatinine from a spot urine specimen.26 crp was log - transformed and modeled as a continuous variable .
diabetes was classified as present if the fasting glucose level was 126 mg / dl or higher ( nonfasting glucose , 200 mg / dl ) or if the participant was taking diabetes medications ( to convert glucose to millimoles per liter , multiply by 0.0555 ) .
urinary albumin and creatinine were used to define the urinary albumin - creatinine ratio ( acr ) .
baseline participant characteristics were tabulated by the categories of natural menopause , bso with or without hysterectomy , hysterectomy alone , and men , using chi - square and anova tests .
cox proportional hazards regression modeling was used to examine the association between menopause type and incident chd with men as a reference for each menopause type .
a parallel set of models was generated that categorized women as being in natural or surgical menopause .
models were adjusted incrementally for age , region ( model 1 ) , and further for education and income ( model 2 ) ; model 2 covariates and total cholesterol , hdl , triglycerides , smoking , exercise , systolic blood pressure , diabetes , acr , use of antihypertensive medications and statins , and crp ( model 3 ) ; model 3 covariates and estrogen therapy at baseline ( model 4 ) ; model 4 covariates and waist circumference and bmi ( model 5 ) ; and model 5 covariates and menopause age dichotomized at 45 years ( model 6 ) . missing data in covariates were imputed using chained equations with 20 data sets , in stata 12 ( statacorp lp , college station , tx).27 to determine whether the relationship between menopause type and chd incidence differed significantly by race , cox models were created that pooled whites and blacks and menopause types and included an interaction term between race and menopause category in the fully adjusted model .
race - stratified models were also created that evaluated an interaction term between age at last menstrual period and type of menopause to determine whether the association between menopause type and incident chd differed in women who were < 45 years versus 45 years of age .
individuals were censored at the time of their event , death , or the end of follow - up .
analyses were conducted using sas ( 9.3 ; sas institute inc . , cary , nc ) and stata 12 .
suspected chd events were adjudicated by a team of experts following published guidelines.20 for mi , medical records were examined for the presence of signs or symptoms suggestive of ischemia ; a rising and/or falling pattern in cardiac troponin level or creatine phosphokinase
myocardial band level over 6 or more hours with a peak level greater than twice the upper limit of normal ( diagnostic cardiac enzymes ) ; and ecg changes consistent with ischemia or mi , guided by the minnesota code and classified as evolving diagnostic , positive , nonspecific , or not consistent with ischemia.21 definite mis were those with diagnostic enzymes or ecg .
probable mis were those with elevated , but not diagnostic ( ie , equivocal ) , enzymes with a positive , but not diagnostic , ecg ; or , if enzymes were missing , with a positive ecg in the presence of ischemic signs or symptoms . only definite or probable
mis were included in this study . for acute chd death , the medical history , hospital records , autopsy reports , interviews with next of kin or proxies , and death certificate or national death index data were reviewed to adjudicate the cause of death , with definite or probable chd death included in this analysis .
cases were assigned to 2 adjudicators and disagreements were adjudicated by committee , with a >0.80 for the presence of definite or probable mi or definite or probable acute chd death .
primary outcomes were total chd events , consisting of definite or probable chd deaths and nonfatal definite or probable mis , as well as acute chd death and nonfatal mi separately .
at baseline , women were asked , have you gone through the change of life ? and how old were you at the time of your last menstrual period ? to identify those with surgical menopause , participants were asked , have you ever had an ovary removed ? if they answered
yes , participants were asked , how many ovaries were removed ? women were also asked , have you ever had a hysterectomy , that is , surgery to remove your uterus or womb ? women were classified as having menopause resulting from bso , with or without hysterectomy ; menopause resulting from hysterectomy alone ; or natural menopause .
women with menopause resulting from bso with or without hysterectomy were defined as such owing to the fact that the ovaries continue to make androgens in postmenopause , even as estrogen production ceases,22 and androgens have been postulated to be influential in atherosclerotic disease in women.23 natural menopause was defined as a last menstrual period occurring 12 months before the interview , in the absence of hysterectomy or bso .
if women had stopped menstruating before hysterectomy or bso , they were defined as being in natural menopause .
age , sex , race , income , education , and smoking status were self - reported .
annual household income was dichotomized at $ 35 000 based on previous analyses in this cohort,24 and education was dichotomized at high school diploma .
smokers were defined as having smoked at least 100 cigarettes in their lifetime and smoking now , even occasionally .
how many times per week do you engage in intense physical activity , enough to work up a sweat ? data on antihypertensive drugs and statin use were based on self - report and in - home pill bottle review , respectively , and data on estrogen therapy were based on in - home reviews conducted by trained interviewers .
anthropometrics and blood pressure were ascertained during an in - home visit using a standardized protocol ; body mass index ( bmi ) and waist circumference have previously been demonstrated to predict mortality risk independently in regards.25 fasting blood and urine markers included total cholesterol , high - density lipoprotein ( hdl ) cholesterol , glucose , high - sensitivity c - reactive protein ( crp ) , serum creatinine , and urinary albumin and creatinine from a spot urine specimen.26 crp was log - transformed and modeled as a continuous variable .
diabetes was classified as present if the fasting glucose level was 126 mg / dl or higher ( nonfasting glucose , 200 mg / dl ) or if the participant was taking diabetes medications ( to convert glucose to millimoles per liter , multiply by 0.0555 ) .
urinary albumin and creatinine were used to define the urinary albumin - creatinine ratio ( acr ) .
baseline participant characteristics were tabulated by the categories of natural menopause , bso with or without hysterectomy , hysterectomy alone , and men , using chi - square and anova tests .
cox proportional hazards regression modeling was used to examine the association between menopause type and incident chd with men as a reference for each menopause type .
a parallel set of models was generated that categorized women as being in natural or surgical menopause .
models were adjusted incrementally for age , region ( model 1 ) , and further for education and income ( model 2 ) ; model 2 covariates and total cholesterol , hdl , triglycerides , smoking , exercise , systolic blood pressure , diabetes , acr , use of antihypertensive medications and statins , and crp ( model 3 ) ; model 3 covariates and estrogen therapy at baseline ( model 4 ) ; model 4 covariates and waist circumference and bmi ( model 5 ) ; and model 5 covariates and menopause age dichotomized at 45 years ( model 6 ) .
missing data in covariates were imputed using chained equations with 20 data sets , in stata 12 ( statacorp lp , college station , tx).27 to determine whether the relationship between menopause type and chd incidence differed significantly by race , cox models were created that pooled whites and blacks and menopause types and included an interaction term between race and menopause category in the fully adjusted model .
race - stratified models were also created that evaluated an interaction term between age at last menstrual period and type of menopause to determine whether the association between menopause type and incident chd differed in women who were < 45 years versus 45 years of age .
individuals were censored at the time of their event , death , or the end of follow - up .
analyses were conducted using sas ( 9.3 ; sas institute inc . , cary , nc ) and stata 12 .
table1 lists the baseline characteristics by menopausal status in blacks ( n=9669 ) and whites ( n=13 417 ) . among blacks , men
were similar in age and education level to women , but men reported higher income .
black men were more likely to smoke , exercise , and had lower bmi than black women , but blood pressure and hdl were poorer . among whites , similar patterns
baseline characteristics of regards cohort members without chd at baseline number ( % ) or means ( sd ) shown , unless otherwise indicated .
chd indicates coronary heart disease ; hdl , high - density lipoprotein ; regards , reasons for geographic and racial differences in stroke ( regards ) cohort .
were of similar age , education , and income , compared to women in surgical menopause , although the proportion of women with menopause at < 45 years of age was lower among women in natural menopause .
surgical menopause was only slightly more common among women living in the stroke belt or buckle than those residing elsewhere .
behaviors such as smoking and exercise were similar across menopause categories , as were metabolic profiles .
black women in natural menopause were less likely to use blood pressure medications and estrogen therapy , compared to black women in surgical menopause . among whites , similar patterns
were observed , except that white women in natural menopause had higher income than white women in surgical menopause .
surgical menopause was more common among white women living in the stroke belt or buckle .
events by nonfatal versus fatal status , sex , menopause type , and race are shown in table2 .
table3 shows the risk of total chd , fatal chd , and nonfatal chd by menopause type , stratified by race .
black women had a significantly lower hazard of any chd event , compared to black men , regardless of menopause type , and white women also had a significantly lower hazard of any chd event , compared to white men , regardless of menopause type . in the fully adjusted model combining blacks and whites with total chd events as the outcome , the race by menopause category interaction term had a p=0.09 .
this interaction was owing to differences in association between menopause category and nonfatal chd events by race .
total , fatal , and nonfatal acute chd events in cox regression models , hazard ratios , and 95% confidence intervals reference group is men .
adjusted for age , age at menopause < 45 years ( yes / no ) , less than high school education , annual income $35 000 ; body mass index , waist circumference , level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensive ( yes / no ) , statins ( yes / no ) , estrogen therapy ( yes / no ) . in minimally- and fully adjusted models , black and white women had a markedly lower hazard of fatal chd events than men , regardless of menopause type ( table3).these associations did not differ by race ( p interaction of menopause category race = 0.89 ) .
figure1 illustrates how the point estimates and 95% confidence intervals ( cis ) for the hazard ratios differed with adjustment for each set of covariates .
whereas 95% cis overlapped , adjustment for age at menopause < 45 years decreased the point estimates , particularly in white women who had undergone hysterectomy ( p=0.04 for interaction for menopause type and age at menopause < 45 years ) .
risk of acute fatal chd events by menopause category ( hazard ratios and 95% confidence intervals ) , with men as referent group .
black participants are shown in the top panel and white participants shown in the bottom panel .
model 2 adjusts for less than high school education and annual income < $ 35 000 . model 3 adjusts for level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensives ( yes / no ) , and statins ( yes / no ) .
model 5 further adjusts for waist circumference ( cm ) and body mass index ( kg / m ) .
model 6 further adjusts for age at last menstrual period < 45 years ( yes / no ) .
bso indicates bilateral oophorectomy ; chd , coronary heart disease ; ci , confidence interval . when we examined risk for nonfatal chd events , a different pattern emerged .
among blacks , women in natural menopause had a slightly lower hazard for nonfatal events than men , although these results did not reach statistical significance ( table3 ) .
women in any type of surgical menopause had a statistically similar hazard for nonfatal chd events . among whites , women in natural menopause had lower risk than men after adjustment for other covariates ( figure2 ) .
white women in surgical menopause also had a decreased hazard for nonfatal events , compared to men , although the cis for subcategories of surgical menopause were wider ( table3 ) .
this difference in patterns between blacks and whites was statistically significant ( p=0.03 for interaction term between race and menopause type in fully adjusted models ) . for white women , in models stratified by age at menopause
< 45 years , similar patterns as the nonstratified analysis were noted ( results not shown ) .
risk of acute nonfatal chd events by menopause category ( hazard ratios and 95% confidence intervals ) , with men as referent group .
black participants are show in the top panel and white participants shown in the bottom panel .
model 2 adjusts for less than high school education and annual income < $ 35 000 .
model 3 adjusts for level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensives ( yes / no ) , and statins ( yes / no ) .
model 5 further adjusts for waist circumference ( cm ) and body mass index ( kg / m ) .
model 6 further adjusts for age at last menstrual period < 45 years ( yes / no ) .
bso indicates bilateral oophorectomy ; chd , coronary heart disease ; ci , confidence interval .
table1 lists the baseline characteristics by menopausal status in blacks ( n=9669 ) and whites ( n=13 417 ) . among blacks , men
were similar in age and education level to women , but men reported higher income .
black men were more likely to smoke , exercise , and had lower bmi than black women , but blood pressure and hdl were poorer . among whites , similar patterns
baseline characteristics of regards cohort members without chd at baseline number ( % ) or means ( sd ) shown , unless otherwise indicated .
chd indicates coronary heart disease ; hdl , high - density lipoprotein ; regards , reasons for geographic and racial differences in stroke ( regards ) cohort .
were of similar age , education , and income , compared to women in surgical menopause , although the proportion of women with menopause at < 45 years of age was lower among women in natural menopause .
surgical menopause was only slightly more common among women living in the stroke belt or buckle than those residing elsewhere .
behaviors such as smoking and exercise were similar across menopause categories , as were metabolic profiles .
black women in natural menopause were less likely to use blood pressure medications and estrogen therapy , compared to black women in surgical menopause . among whites , similar patterns
were observed , except that white women in natural menopause had higher income than white women in surgical menopause .
surgical menopause was more common among white women living in the stroke belt or buckle .
events by nonfatal versus fatal status , sex , menopause type , and race are shown in table2 .
table3 shows the risk of total chd , fatal chd , and nonfatal chd by menopause type , stratified by race .
black women had a significantly lower hazard of any chd event , compared to black men , regardless of menopause type , and white women also had a significantly lower hazard of any chd event , compared to white men , regardless of menopause type . in the fully adjusted model combining blacks and whites with total chd events as the outcome , the race by menopause category interaction term had a p=0.09 .
this interaction was owing to differences in association between menopause category and nonfatal chd events by race .
total , fatal , and nonfatal acute chd events in cox regression models , hazard ratios , and 95% confidence intervals reference group is men .
adjusted for age , age at menopause < 45 years ( yes / no ) , less than high school education , annual income $35 000 ; body mass index , waist circumference , level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensive ( yes / no ) , statins ( yes / no ) , estrogen therapy ( yes / no ) .
in minimally- and fully adjusted models , black and white women had a markedly lower hazard of fatal chd events than men , regardless of menopause type ( table3).these associations did not differ by race ( p interaction of menopause category race = 0.89 ) .
figure1 illustrates how the point estimates and 95% confidence intervals ( cis ) for the hazard ratios differed with adjustment for each set of covariates .
whereas 95% cis overlapped , adjustment for age at menopause < 45 years decreased the point estimates , particularly in white women who had undergone hysterectomy ( p=0.04 for interaction for menopause type and age at menopause < 45 years ) .
risk of acute fatal chd events by menopause category ( hazard ratios and 95% confidence intervals ) , with men as referent group .
black participants are shown in the top panel and white participants shown in the bottom panel .
model 2 adjusts for less than high school education and annual income < $ 35 000 . model 3 adjusts for level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensives ( yes / no ) , and statins ( yes / no ) .
model 5 further adjusts for waist circumference ( cm ) and body mass index ( kg / m ) .
model 6 further adjusts for age at last menstrual period < 45 years ( yes / no ) .
bso indicates bilateral oophorectomy ; chd , coronary heart disease ; ci , confidence interval .
when we examined risk for nonfatal chd events , a different pattern emerged . among blacks , women in natural menopause had a slightly lower hazard for nonfatal events than men , although these results did not reach statistical significance ( table3 ) .
women in any type of surgical menopause had a statistically similar hazard for nonfatal chd events . among whites , women in natural menopause had lower risk than men after adjustment for other covariates ( figure2 ) .
white women in surgical menopause also had a decreased hazard for nonfatal events , compared to men , although the cis for subcategories of surgical menopause were wider ( table3 ) .
this difference in patterns between blacks and whites was statistically significant ( p=0.03 for interaction term between race and menopause type in fully adjusted models ) . for white women , in models stratified by age at menopause < 45 years , similar patterns as the nonstratified analysis were noted ( results not shown ) .
risk of acute nonfatal chd events by menopause category ( hazard ratios and 95% confidence intervals ) , with men as referent group .
black participants are show in the top panel and white participants shown in the bottom panel .
model 2 adjusts for less than high school education and annual income < $ 35 000 . model 3 adjusts for level of total cholesterol , high - density lipoprotein cholesterol , systolic blood pressure , albumin - creatinine ratio , and c - reactive protein ; current smoking ( yes / no ) , diabetes ( yes / no ) , never exercise ( yes / no ) , use of antihypertensives ( yes / no ) , and statins ( yes / no ) .
model 5 further adjusts for waist circumference ( cm ) and body mass index ( kg / m ) .
model 6 further adjusts for age at last menstrual period < 45 years ( yes / no ) .
bso indicates bilateral oophorectomy ; chd , coronary heart disease ; ci , confidence interval .
in the regards study , in both blacks and whites , women had a lower risk of total chd events than men , regardless of menopause category .
compared to black men , black women had approximately half the hazard of any chd event , compared to men .
compared to white men , white women also had a significantly reduced hazard of chd .
these sex differences were even more pronounced for risk of acute fatal chd events in both blacks and whites . however , sex differences were less pronounced for nonfatal chd events .
patterns varied by race , with no significant sex differences observed in nonfatal chd risk among blacks .
white women in natural menopause and surgical menopause continued to have lower nonfatal chd risk than men .
thus , frequency of surgical menopause was not responsible for the lack of sex differences in nonfatal chd in blacks as opposed to whites .
our results confirm that the risk of having any incident chd event in women is lower than in men.2 we also note that this low risk persists despite the postmenopausal state , regardless of menopause type , and despite comprehensive adjustment for traditional and unconventional chd risk factors , including renal function , crp , and medication use .
this suggests that other factors besides menopause status and chd risk factors are driving sex differences in mid - life .
previous investigators noted that although the risk of incident chd increases rapidly in women after 50 years of age , the approximate age of menopause , evaluation of risk for chd changes on a log - scale reveal a gradual increase in risk rather than a sharp change in risk ( as is observed for breast cancer).2,5 therefore , men may have a slower rate of increase in chd events in mid - life , whereas women s rate of increase remains constant.2,5 in other words , the greater sex differences observed at younger ages , as opposed to older ages , may be owing to changing risk in men rather than women , as well as the difficulty in demonstrating greater relative differences in events as the number of events increases . to our knowledge
, other reports have not examined the impact of menopause type upon sex differences in chd risk .
previous literature has conflicted regarding the degree of chd risk conferred by different types of menopause . in the women
s health initiative observational study , the risk of any cve associated with menopause type was examined , using natural menopause as a referent group ; cv disease was defined as mi , stroke , coronary revascularization , or chd death .
women who had undergone hysterectomy had a poorer chd risk profile than women in natural menopause , regardless of oophorectomy status , and the increased risk associated with hysterectomy was diminished after adjustment for chd risk factors.28 in the nurses health study , bso was associated with increased chd risk , compared to natural menopause , after adjustment for age and smoking.7 a more recent analysis suggested that bso was associated with greater chd risk , compared to hysterectomy alone , after adjustment for a more extensive list of covariates than age and smoking.8 our results are similar to these findings , in that we found that , of all the menopause categories , black and white women in natural menopause had the lowest risk of nonfatal chd events , compared to men .
our report differs from previous studies that suggested women in surgical menopause might lose their advantage , compared to men , even as men were not examined along with subtype of menopause .
analyses in other cohorts have reported that women who undergo surgical menopause tend to have poorer chd risk factor profiles29 than other women , particularly among blacks.30 one exception reported that annual changes in chd risk factors did not vary by menopausal type.18 we found that surgical menopause was not associated with a greater risk of fatal chd events .
though the sudden cardiac death that comprises a subset of fatal chd is more common in men than women , myocardial ischemia is believed to be the primary etiology.31 however , other reports have noted that testosterone levels are inversely associated with qt intervals in men , but not women,32 and it is possible that the higher androgen levels observed in men confer a relative disadvantage regarding arrhythmias . the risk of acute chd events has also declined with time , a finding attributed to more - intensive chd risk factor management with lifestyle modification and pharmacotherapy.33 it is possible that these secular trends may have contributed to the decrease in chd risk associated with surgical menopause .
we also found that the black women who underwent surgical menopause and natural menopause in regards had a similar risk of nonfatal chd events , compared to black men , regardless of menopause type .
white women , particularly white women who underwent natural menopause , had a lower risk of nonfatal chd events , compared to white men .
it is possible that the androgen production that distinguishes menopause types22 is influential in the pathophysiology of the diffuse atherosclerosis that characterizes nonfatal events , and racial / ethnic differences by androgen level exist .
previous studies have conflicted as to whether black and white women have different levels of androgens,3437 so it is unknown whether differences in androgen profile might explain risk in whites , but not blacks .
persistence of these patterns after adjustment for an extensive list of chd risk factors suggests that a higher risk - factor burden in blacks does not contribute .
younger age at menopause was associated with increased hazard of fatal chd in white women , given that adjustment for this factor increased women s advantage , compared to men .
previous studies have noted consistent relationships with younger age at menopause in white populations and increased risk of any chd event,13,14 particularly fatal chd . smoking increases risk of earlier menopause,14 although the association persisted after adjustment for smoking .
it is possible that the changes in sex steroid profile that characterize the menopause may be cumulative over time , with younger ages at menopause leading to increased risk .
adjustment for age at menopause led to minimal change among blacks , perhaps related to the reduced sex differences among blacks . despite the large numbers of black and white participants , the number of fatal chd events was modest , and estimates of fatal chd risk should be interpreted with caution .
women who had undergone menopause as a result of hysterectomy alone have been reported to have slight reductions in androgens , but with smaller reductions compared to women in natural menopause or with bso ( presumably owing to unintended ovarian infarction during oophorectomy ) and thus were defined as such.22 women tend to under - report bso in the context of hysterectomy,39 and thus the category of women with hysterectomy only may have included women with bilateral oophorectomy as well .
studies have reported high correlation between ultrasound scans and self - report of hysterectomy,40 whereas the positive predictive value for self - report of oophorectomy is lower.39 precise measures of diet and physical activity were not available .
strengths of this study include its large sample size and national sampling frame , allowing adjustment for regional variation in surgeries and chd risk , as well as stratified analyses by race .
additional strengths included adjudication of chd endpoints as well as examination of chd alone instead of a composite endpoint .
in addition , regards measured a comprehensive list of both classic and nontraditional chd risk factors that were included in adjustment .
finally , the examination of race and sex differences has not previously been examined . in a national population - based sample of blacks and whites
, we found that menopausal women had a lower risk of chd events than men after consideration of an extensive list of potential confounders .
this advantage was particularly pronounced for fatal chd events , regardless of menopause type , in both whites and blacks .
regarding nonfatal chd events , white women retained their advantage regardless of menopause type , whereas black women had a similar risk to black men for nonfatal chd events regardless of menopause type .
for black women , our findings are reassuring , in that chd risk does not seem to vary significantly by menopause type , compared to men , and , moreover , that women have lower risk for fatal chd , even in postmenopause , compared to men . for white women , women are still at lower risk than men for any type of chd event .
exploration of factors that contribute nonfatal mi , and , particularly , to the sex advantage in white women , compared to white men , and the absence of this advantage in black women and black men , is needed .
this research project is supported by a cooperative agreement u01 ns041588 from the national institute of neurological disorders and stroke , national institutes of health , department of health and human services .
the content is solely the responsibility of the authors and does not necessarily represent the official views of the national institute of neurological disorders and stroke or the national institutes of health .
additional funding is provided by grants r01 hl080477 and k24 hl111154 from the national heart , lung , and blood institute .
funders had no role in the design and conduct of the study ; collection , management , analysis , and interpretation of the data ; preparation , review , or approval of the manuscript ; and decision to submit the manuscript for publication .
| backgroundwe examined whether type of menopause affects sex differences in coronary heart disease ( chd ) events and whether the impact is similar in blacks and whites.methods and resultsparticipants were enrolled in the reasons for geographic and racial differences in stroke ( regards ) cohort between 2003 and 2007 without chd at baseline ( n=23 086 ) .
cox regression models were used to calculate the hazard of incident nonfatal chd ( definite or probable myocardial infarction ) and acute chd death , adjusting for age , age at last menstrual period < 45 years , region , education level , income , diabetes , smoking , systolic blood pressure , lipid levels , albumin - creatinine ratio , physical activity , c - reactive protein , body mass index , waist circumference , and medication use .
white women in natural menopause ( hazard ratio [ hr ] , 0.45 ; 95% confidence interval [ ci ] , 0.31 , 0.66 ) and surgical menopause ( hr , 0.65 ; 95% ci , 0.42 , 0.99 ) had a reduced hazard of nonfatal events , compared to white men .
black women in natural menopause ( hr , 0.69 ; 95% ci , 0.47 , 1.03 ) , but not surgical menopause ( hr , 0.81 ; 95% ci , 0.51 , 1.29 ) , had a marginally reduced hazard of nonfatal events , compared to black men .
women had lower risk of acute chd death than men regardless of their menopause type and race.conclusionssex differences in the risk of incident chd events were larger among whites than blacks and varied by type of menopause .
women consistently had a lower risk of incident chd death than men , but the magnitude of sex differences was greater in whites than blacks for nonfatal events , regardless of menopause type . |
stellar population models are powerful tools which are widely used to study galaxy evolution .
using these models , one can determine galaxy ages , metallicities and abundances .
spectral libraries are an integral component of stellar population models ( e.g. @xcite ) .
a spectral library gives the behavior of individual stellar spectra as function of effective temperature ( @xmath1 ) , gravity ( @xmath2 ) and metallicity ( [ fe / h ] ) .
a stellar population model integrates these spectra together with a set of stellar isochrones and an initial mass function to produce a model spectrum of an entire population . in order to reproduce galaxy spectra as precisely as possible
, one requires a comprehensive stellar spectral library that covers the entire desired parameter space of @xmath1 , @xmath2 , and [ fe / h ] . moreover , extended wavelength coverage is strongly desirable , because different stellar phases contribute their light in different bands .
for instance , bright giants contribute more light in the near - infrared than the faint giant and subgiant stars , while in the optical , the situation is reversed @xcite .
these asymptotic giant branch ( agb ) stars dominate the light of intermediate - aged and old stellar populations in the near - infrared but are unimportant in the optical ( e.g. , @xcite ) . detecting their presence requires _ broad wavelength coverage _ in both the target and model spectra .
stellar spectral libraries can be classified into empirical and theoretical libraries , depending on how the library is obtained .
both theoretical and empirical libraries have improved in recent years . the most widely used theoretical libraries in stellar population models are those of @xcite , @xcite , @xcite , @xcite , @xcite , and @xcite .
theoretical libraries have the advantage of ( nearly ) unlimited resolution and selectable abundance patterns not only scaled - solar abundances but also non - solar patterns . unfortunately ,
theoretical libraries suffer from systematic uncertainties , as they rely on model atmospheres and require a reliable list of atomic and molecular line opacities @xcite .
empirical stellar libraries , on the other hand , have the advantage of being drawn from real , observed stars and therefore do not suffer this limitation ; however they frequently have relatively low resolution ( with a few exceptions ; see below ) and are unable to reproduce the indices measured in giant elliptical galaxies @xcite , because they are based on local stars with typical milky way disk abundance patterns .
in this proceeding we present the x - shooter stellar library , xsl .
xsl is being obtained using the new x - shooter three - arm spectrograph on eso s vlt @xcite .
xsl has the unique advantage of simultaneously acquiring spectra covering the near - ultraviolet up to the near - infrared .
furthermore , the fact that x - shooter is mounted on an 8.2-m telescope allows us to include faint objects in stars in the galactic bulge and the magellanic clouds for the first time , along with stars in the galactic disk and halo , at moderate spectral resolution ( @xmath0 ) . *
5l library&resolution&spectral range&number & reference&r=@xmath3&(nm)&of stars&stelib & 2000 & 320 - 930 & 249 & @xciteelodie & 10000 & 390 - 680 & 1300 & @xciteindo - us & 5000 & 346 - 946 & 1237&@xcitemiles & 2000 & 352 - 750 & 985 & @xciteirtf - spex & 2000 & 800 - 2500 & 210 & @xcitengsl & 1000 & 167 - 1025 & 374 & @xciteuves - pop & 80000 & 307 - 1030 & 300 & @xcitelw2000 & 1100 & 500 - 2500 & 100 & @xcite we begin with a review of several previous empirical stellar libraries and their principal features , listed in table [ tablib ] . in the optical , we have ( among others ) lick / ids @xcite , miles @xcite , elodie @xcite , stelib @xcite , ngsl @xcite , and the pickles library @xcite .
libraries in the near - ir are a challenging task , but pioneering work has been done by lanon and wood @xcite ( lw2000 ) , rayner et al .
@xcite ( irtf - spex ) , and mrmol - queralt et al .
however , extended - wavelength - coverage spectral libraries at moderate resolution are still largely missing .
stelib @xcite has been used to construct the widely used stellar population synthesis models of bruzual & charlot 2003 ( @xcite , here after bc03 ) .
this library has a wide wavelength range , 32009300 , at modest resolution ( @xmath4 ) .
the spectra of local galaxies have been reproduced by the models of bc03 through this library @xcite .
however , stars with low and high metallicites are sparse in this library , leading to problems in some regimes , like modeling old , metal - poor globular cluster spectra @xcite .
the elodie library @xcite is a moderate - resolution spectral library with @xmath0 .
it has been applied in the pgase - hr synthetic model @xcite .
the atmosphere parameter coverage of this library had been improved through its updated version , but the wavelength range is still limited in the optical region ( 41006800 ) .
the indo - us library @xcite includes a large number of stars ( 1273 ) , covers a fair range in atmosphere parameters with moderate - resolution ( @xmath5 ) .
atmospheric parameters of its stars are given in wu et al .
the data have been used for automated spectral classification of high - resolution spectra over a wide wavelength range @xcite .
the problem of this library is the lack of accurate spectrophotometry , making inclusion in stellar population models problematic . the miles library @xcite is widely used in stellar population models .
this library profits from its good physical parameter coverage , careful flux calibration , and a large number of stars ( 985 ) , enabling stellar population models to predict metal - poor or metal - rich systems .
the miles library s wavelength range covers 35007500 at modest resolution ( @xmath4 ) @xcite .
the next general spectral library ( ngsl , @xcite ) is a low resolution ( @xmath6 ) stellar library obtained with stis on hst .
it contains @xmath7 stars having a wide range in metallicity and age . since its spectra
were observed in space , this library does not suffer from telluric absorption or seeing variations , and hence has excellent absolute spectrophotometry .
other features of ngsl are its broad wavelength coverage , from the space uv to 1 @xmath8 m , and high signal - to - noise .
there is also a high - resolution ( @xmath9 , covering 360011000 ) extension of ngsl s southern stars taken with the uves spectrograph of eso s vlt ( hanuschik et al . , in prep . ) . the uves paranal observatory project ( uves - pop , @xcite ) is a library of spectra of @xmath10 nearby bright stars taken with uves . the spectra
cover the optical region at @xmath11 and have a typical s / n ratio is 300500 in the @xmath12 band .
the library has been flux calibrated but has not been corrected for the severe telluric absorption in the red . for stellar population models the sample is incomplete , since it only contains bright stars around solar metallicity . in the near - infrared range , the irtf spectral library ( irtf - spex , @xcite ) contains 200 stars observed with the cross - dispersed infrared spex spectrograph on irtf at a resolving power of @xmath4 .
the largest spectral library of very cool supergiants and giants over the wavelength range @xmath132.5 @xmath8 m was published by lanon & wood ( lw2000 , @xcite ) , which contains @xmath14 stars taken at a resolution of @xmath15 , including observations over multiple phases .
unfortunately , cool giants are variable in optical and nir , so simultaneous observations are required .
libraries with more limited spectral coverage in the near - infrared , like the 2.3 @xmath8 m library of marml - queralt et al .
@xcite , also exist , but are limited to a small number of spectral features ( like the co bandhead ) .
x - shooter @xcite was built by a consortium of 11 institutes in denmark , france , italy and the netherlands , together with eso .
it is currently mounted on ut2 on eso s vlt .
a unique capability of x - shooter is that it collects spectra in the wavelength range from the near - ultraviolet to the near - infrared
3002500 nm through its three arms _ simultaneously_. this character is extremely useful for observing variable stars , especially very cool stars like stars whose spectra vary substantially during their pulsation cycles .
xsl targets were selected from many of the above libraries as well as supplementary literature sources .
we took stars from lick / ids , miles , and ngsl to cover @xmath1 , @xmath2 , and [ fe / h ] as uniformly as possible .
however , these libraries mostly lack the cool , bright stars so important in the near - infrared . for this purpose we selected agb and lpv stars from lw2000 and irtf - spex with declination @xmath16 marked m , c or s - stars .
long - period variable ( lpv ) stars were also collected from the lmc @xcite and smc @xcite .
red supergiant stars were taken from the lists of lw2000 and @xcite . to cover metal - rich stars with abundances similar to giant elliptical galaxies
, we also included galactic bulge giants from the samples of @xcite .
our intention is that xsl will contain about 600 stars at the end of the survey .
hr diagram of the 114 x - shooter library stars with known @xmath17 and @xmath2 .
bottom axis is @xmath17 ; top axis is log @xmath18 , where @xmath18 = 5040/@xmath17 . ]
hr diagram of the 114 x - shooter library stars with known @xmath17 and @xmath2 .
bottom axis is @xmath17 ; top axis is log @xmath18 , where @xmath18 = 5040/@xmath17 . ] to date , 251 observations of 236 unique stars from the xsl input catalog have been made .
[ obaf ] shows the distribution of our sample stars with different stellar types .
we have collected a large sample of m , c , and lpv stars , interesting for many different cool star studies . in fig .
[ param ] we show those sample stars with known stellar parameters in an hr diagram .
the targets were observed with x - shooter with a @xmath19 slit in the uvb arm ( 30006000 , @xmath20 ) , a @xmath21 slit in the vis arm ( 600010200 , @xmath22 ) , and a @xmath23 slit in the nir arm ( 12.5 @xmath8 m , @xmath24 ) .
stars were nodded along the slit to remove the sky background , a serious problem in the nir arm even for very short exposures . in addition , for every star a wide ( @xmath25 ) slit spectrum was taken to allow for excellent flux calibration ( see , e.g. , @xcite ) . a sample of xsl stellar spectra sorted by temperature .
grey bars cover areas of severe ( light grey ) or nearly complete ( dark grey ) telluric absorption in the nir arm . ]
the basic data reduction was performed with the public release of the x - shooter pipeline version 1.1.0 , following its standard steps up to the production of 2d spectra , including bias and/or dark correction , flat - fielding , wavelength calibration , sky subtraction .
we then used iraf s ` twodspec.apextract ` routine to extract 1d spectra from the 2d spectra .
we show typical x - shooter library spectra in fig .
[ nstar ] , which contains several spectral types from b2 to m3 . in this figure flux calibration has been applied to all the three arms .
the uvb arm is shown in blue , the vis arm in green and the nir arm in red .
telluric corrections have been applied to the vis and nir arms .
grey bars demonstrate the telluric regions in the nir arm , in which the light grey bars cover the areas of severe telluric absorption while the dark grey ones cover the areas nearly complete telluric absorption .
since x - shooter is a ground based instrument , correction for telluric absorption in the vis and nir arm spectra is very important .
for this reason a hot star ( typically a mid - b dwarf ) was observed after every science object at a similar airmass .
unfortunately , the telluric absorption lines change strength on timescales shorter than the `` long '' exposure times ( @xmath26 seconds ) of faint xsl stars and the total observational overhead time of @xmath27 seconds , resulting in a noisy telluric correction . to optimize the telluric correction
, we built a telluric stellar spectrum library , in which the hot stars were carefully wavelength calibrated .
first we masked out strong h and other lines from the telluric region , since we know that b and other hot stars usually have strong h lines which must be corrected before the spectra can be used as telluric templates .
we then normalized the masked spectra to create our telluric standard library . for each science object , we defined several telluric absorption regions and ran the spectral - fitting program ppxf @xcite to find a `` best fit '' telluric correction spectrum .
we fitted the science spectrum with a linear combination of the spectra in the ( normalized ) telluric library , fitting at the same time the line - broadening of the science spectra , and multiplying the result with a higher order polynomial .
this step gave a `` best fit '' for the telluric absorption features to every science object .
we then divided the science spectrum by this `` best fit '' , resulting in a telluric - corrected science spectrum .
[ eg0 ] shows an example of hd 284248 in the vis arm ( without flux calibration ) , where the black line is the original reduced spectrum before telluric correction and the red line is after correction . to show the quality of the correction in more detail , we zoom into the telluric - corrected spectrum in atmospheric `` a '' band between 758 and 776 nm in fig . [ eg1 - 4 ] . to perform a reliable flux calibration
, we observed several spectrophotometric standards ( bd+17 4708 , gd71 , ltt1020 , gd153 , eg274 and eg21 ) with a wide ( @xmath25 ) slit in `` stare '' mode at different airmasses .
these flux standard star were then reduced and extracted through the procedures mentioned above .
the spectra were compared with the flux tables of the appropriate stars from the calspec hst database @xcite and averaged to produce the response function .
the paranal extinction curve @xcite was applied to perform the atmosphere extinction correction .
[ flx ] shows the flux - calibrated vis arm spectrum of hd 8724 from x - shooter ( black line ) and ngsl ( red line ) .
the uvb arm spectra are corrected in a similar matter .
the nir arm spectra will be telluric- and flux - calibrated simultaneously using the hot star telluric correction spectra in combination with the flux standards .
xsl , the x - shooter stellar library , is intended to be the largest stellar library with complete wavelength coverage from 3202480 nm and covering as large a range in stellar atmospheric parameters as possible .
we will soon have a first version of xsl with spectra of @xmath28 stars .
the final library will contain @xmath29 stars at moderate resolution ( @xmath0 ) .
the stellar parameter coverage will be enforced through carefully selected samples , so that not only stars with solar metallicities and abundances are included but also metal - poor or metal - rich stars from the bulge and magellanic clouds . with x - shooter s unique capability ,
the variable stars will be observed consistently , which will yield more reliable stellar population models .
we thank our collaborators on the first phase of xsl , d. silva and p. prugniel , and b. davies and m. koleva for useful discussions .
we would also like to extend our great thanks to v. manieri , a. modigliani , j. vernet , and the eso staff for their help during the xsl observations and reduction process .
10 url # 1#1urlprefix[2][]#2 bruzual a g and charlot s 2003 _ mnras _ * 344 * 1000 vernet j , dekker h , dodorico s , masonand e , di marcantonio p , downing m , elswijk e , finger g , fischer g , kerber f , kern l , lizon j l , lucuix c , mainieri v , modigliani a , patat f , ramsay s , santin p , vidali m , groot p , guinouard i , hammer f , kaper l , kjrgaard - rasmussen p , navarro r , randich s and zerbi f 2010 _ society of photo - optical instrumentation engineers ( spie ) conference series _
( _ society of photo - optical instrumentation engineers ( spie ) conference series _
vol 7735 ) p 50 patat f , moehler s , obrien k , pompei e , bensby t , carraro g , de ugarte postigo a , fox a , gavignaud i , james g , korhonen h , ledoux c , randall s , sana h , smoker j , stefl s and szeifert t 2011 _ a&a _ * 527 * 91 | we are building a new spectral library with the x - shooter instrument on eso s vlt : xsl , the x - shooter spectral library .
we present our progress in building xsl , which covers the wavelength range from the near - uv to the near - ir with a resolution of @xmath0 . at the time of writing
we have collected spectra for nearly 240 stars .
an important feature of xsl is that we have already collected spectra of more than 100 asymptotic giant branch stars in the galaxy and the magellanic clouds . |
The officials said the intercepted communications were not limited to Trump campaign officials, and included other associates of Mr. Trump. On the Russian side, the contacts also included members of the government outside of the intelligence services, they said. All of the current and former officials spoke on the condition of anonymity because the continuing investigation is classified.
The officials said that one of the advisers picked up on the calls was Paul Manafort, who was Mr. Trump’s campaign chairman for several months last year and had worked as a political consultant in Ukraine. The officials declined to identify the other Trump associates on the calls.
The call logs and intercepted communications are part of a larger trove of information that the F.B.I. is sifting through as it investigates the links between Mr. Trump’s associates and the Russian government, as well as the hacking of the D.N.C., according to federal law enforcement officials. As part of its inquiry, the F.B.I. has obtained banking and travel records and conducted interviews, the officials said.
Mr. Manafort, who has not been charged with any crimes, dismissed the officials’ accounts in a telephone interview on Tuesday. “This is absurd,” he said. “I have no idea what this is referring to. I have never knowingly spoken to Russian intelligence officers, and I have never been involved with anything to do with the Russian government or the Putin administration or any other issues under investigation today.”
He added, “It’s not like these people wear badges that say, ‘I’m a Russian intelligence officer.’”
Several of Mr. Trump’s associates, like Mr. Manafort, have done business in Russia. And it is not unusual for American businessmen to come in contact with foreign intelligence officials, sometimes unwittingly, in countries like Russia and Ukraine, where the spy services are deeply embedded in society. Law enforcement officials did not say to what extent the contacts might have been about business. ||||| (CNN) High-level advisers close to then-presidential nominee Donald Trump were in constant communication during the campaign with Russians known to US intelligence, multiple current and former intelligence, law enforcement and administration officials tell CNN.
President-elect Trump and then-President Barack Obama were both briefed on details of the extensive communications between suspected Russian operatives and people associated with the Trump campaign and the Trump business, according to US officials familiar with the matter.
Both the frequency of the communications during early summer and the proximity to Trump of those involved "raised a red flag" with US intelligence and law enforcement, according to these officials. The communications were intercepted during routine intelligence collection targeting Russian officials and other Russian nationals known to US intelligence.
Among several senior Trump advisers regularly communicating with Russian nationals were then-campaign chairman Paul Manafort and then-adviser Michael Flynn.
Officials emphasized that communications between campaign staff and representatives of foreign governments are not unusual. However, these communications stood out to investigators due to the frequency and the level of the Trump advisers involved. Investigators have not reached a judgment on the intent of those conversations.
Adding to US investigators' concerns were intercepted communications between Russian officials before and after the election discussing their belief that they had special access to Trump, two law enforcement officials tell CNN. These officials cautioned the Russians could have been exaggerating their access.
Trump dismissed the claims that his advisers had close ties to Russia in a tweet Wednesday.
"This Russian connection non-sense is merely an attempt to cover-up the many mistakes made in Hillary Clinton's losing campaign," Trump tweeted.
CNN has reached out to Flynn for comment. In an interview, Manafort emphatically denied that he was in contact with Russians known to US intelligence.
"That is 100% not true, at least as far as me," he said. "I cannot believe that they are including me in anything like that. I have not been involved in any of these activities."
Manafort said he did not know where US officials got the idea that he was in contact with suspected Russian operatives during the campaign but said he never spoke with any Russian officials during that time.
"I don't remember talking to any Russian officials, ever. Certainly during the time we're talking about," he said, calling the allegations "boggling."
"I have knowingly never talked to any intelligence official or anyone in Russia regarding anything of what's under investigation," he said. "I have never had any connection to (Russian President Vladimir) Putin or the Russian government before, during or after the campaign."
Manafort said the FBI has not contacted him about the allegations and said he was not aware of any other Trump campaign officials or people close to Trump being in touch with Russians known to US intelligence.
Manafort, who has held business ties with Russian and Ukrainian individuals, also emphasized that his work for the Yanukovich government in Ukraine should not be interpreted as closeness to the Russians. He said he worked for Yanukovich during a time when Ukraine was "moving into the European orbit."
The extensive contacts drew concerns of US intelligence and law enforcement officials in part because it came at a time of Russian cyberactivities targeting mostly Democratic Party political organizations
Post-election intelligence briefings on Russian meddling in the US elections included details of those communications, which included people involved in Trump's businesses.
The communications were gathered as part of routine US intelligence collection and not because people close to Trump were being targeted.
The FBI and US intelligence agencies continue to try to determine what the motive for the communications were.
One concern was whether Trump associates were coordinating with Russian intelligence operatives over the release of damaging information about the Hillary Clinton campaign.
"If that were the case, then that would escalate things," one official briefed on the investigation said. | – The Trump administration's Russia problem just got a lot worse, according to the New York Times' sources: Four officials say intelligence agencies have uncovered phone records and other evidence that members of Trump's campaign team and other aides were in contact with senior Russian officials during the campaign. The sources say that after routine NSA surveillance revealed the Trump associates' contact with Russian officials, the FBI made monitoring those officials a priority. CNN's sources say the Trump associates, including business contacts as well as high-level campaign aides, were in "constant communication" with the Russians, "raising a red flag" for intelligence agencies and law enforcement. The Times' sources say former Trump campaign Chairman Paul Manafort is among those being investigated, though he strongly denies having improper contacts. "I have never been involved with anything to do with the Russian government or the Putin administration or any other issues under investigation today," he says, adding: "It's not like these people wear badges that say, 'I'm a Russian intelligence officer.'" Kremlin spokesman Dmitry Peskov denied the report Tuesday, saying it's "not based on any facts," the AP reports. The Guardian notes that the new report of Russian links is trouble for Trump for several reasons, including the fact that it shows intelligence officials are still willing to leak material damaging to his administration. |
ewing 's sarcoma is a malignant nonosteogenic primary tumor of the bone , which is mainly seen in the diaphysis of the long bones and the flat bones of the pelvis in young patients . originally , james ewing described it as a tumor arising from undifferentiated osseous mesenchymal cells ; however , recent studies suggest that ewing 's tumor may be neuroectodermally derived from the primitive neural tissue.1 this tumor is stated to comprise approximately 6% of the total malignant bone tumors , but is exceptionally rare in the small bones of hands and feet , where the reported incidence is not more than 1%.2
a previously healthy 10-year - old girl presented with a large swelling arising from the right little finger of 6 months duration .
the swelling was initially small and painless to start with and was associated with fever and chills .
she was seen at a local hospital , where a radiograph was taken which revealed a cystic and lytic lesion of the little finger proximal phalanx [ figure 1 ] .
it was diagnosed as osteomyelitis , and she was treated with analgesics and antibiotics . as the swelling and pain progressed , she was referred to this institute .
the swelling was 6 6 cm , tender , pulsatile and firm in consistency .
the fresh radiograph showed a large soft tissue mass with some calcification within and complete destruction of the phalanx [ figure 2a and b ] . magnetic resonance imaging ( mri )
scan of the hand revealed an ill defined expansible lesion in the proximal phalanx with marrow signal changes that were t1 hypointense and t2/short tau inversion recovery hyperintense with juxtacortical soft tissue mass [ figure 3 ] .
fine needle aspiration cytology ( fnac ) of the lesion was performed and reported as having features of small blue round cell tumor .
computed tomography ( ct ) of the chest , abdomen , and pelvis was normal .
histopathology of excised tissue showed small round cells with high nuclear - cytoplasmic ratio and coarse chromatin with occasional pseudorosettes , suggestive of ewing 's sarcoma .
the cells were periodic acid schiff positive and immunohistochemistry was positive for cd99 [ figure 4a and b ] .
initial radiograph of hand anteroposterior view showing a cystic , lytic lesion with minimal periosteal reaction in the proximal phalanx ( a ) clinical photograph of hand showing swelling at the time of presentation to us about the size of a golf ball ( b ) .
radiograph of hand anteroposterior view showing destruction of the entire phalanx with large soft tissue component magnetic resonance imaging in t1 and t2/soft tissue inflammatory response sequences showing the extent of the lesion in the little finger periodic acid schiff positivity of the cells seen ( a ) and immunohistochemistry showing positivity with cd99 ( b ) the patient was discharged and advised to review after 3 weeks for chemotherapy .
however , the patient was non - compliant and returned about 4 months after the surgery with pain and swelling of the dorsum of the hand with dilated veins [ figure 5a ]
blood investigations revealed hemoglobin of 9 g% and erythrocyte sedimentation rate ( esr ) 42 mm at 1 h. radiograph revealed cystic lesion in the third metacarpal diaphysis with sclerosis and minimal periosteal reaction [ figure 5b ] .
mri scan showed marrow signal changes involving second , third and fourth metacarpal bones with cortical erosion and breakdown of third metacarpal bone [ figure 6 ] .
the chest metastasis has partially resolved , and there is no local recurrence or evidence of metastasis to other sites .
( a ) clinical photograph at followup after 3 months shows discernible fullness over dorsum of the hand .
( b ) radiograph of hand anteroposterior view showing destruction of the third metacarpal with little periosteal reaction magnetic resonance imaging revealing marrow signal changes involving the second , third and fourth metacarpals with cortical breakdown of third metacarpal in t1 and t2 sequences
ewing 's sarcoma is the second most common malignant primary bone tumor of childhood and adolescence.3 bernstein et al . , reporting 1426 patients from the european intergroup cooperative ewing sarcoma study , recorded only 1% of primary ewing 's sarcomas in the hand.4 case reports indicate that within the hand , the metacarpal is the most common locale.56 ewing 's sarcoma / primitive neuroectodermal tumor classically presents mimicking an acute infection with pain , swelling , and erythema in the affected area with associated leukocytosis and raised esr.7 siddiqui et al . reported a case of calcaneal ewing 's sarcoma with skip metastasis to adjacent tarsal bones.1 to the best of our knowledge , this is the first reported case of ewing 's sarcoma arising from phalanx of the hand with skip metastases to multiple metacarpals .
investigative modalities done as a routine for tumor work up includes a radiograph of the part , mri scan , complete blood work up , chest x - ray , ct / ultrasonography of abdomen and tc 99 bone scan.7
f - fluorodeoxyglucose positron emission tomography - ct scan is a newer and excellent modality to detect unsuspected or unusual metastatic sites , monitor response to chemo or radiotherapy and to detect recurrence in primary skeletal ewing 's sarcoma.89 reinus et al .
when studying the radiographic appearance of ewing 's sarcoma of hands and feet , found that the most common feature was that of a permeative bone lesion with poorly defined margins and an associated soft tissue mass.10 even in our patient , the early x - rays revealed a cystic and lytic lesion with large soft tissue mass with some sclerosis and negligible periosteal reaction .
knowledge of the often atypical radiological appearance of ewing 's sarcoma of the hand is important in ensuring a prompt and accurate diagnosis.3 the differential diagnosis of this lesion includes osteomyelitis , spina ventosa , enchondroma , coccidioidomycosis , bone infarction and hand foot syndrome of sickle cell disease.3 the prognosis does not appear to be related to the radiographic appearance or dimension of the primary lesion but to the presence of known metastasis at the time of presentation.10
management , preferably at a specialist center by a multi disciplinary team , has included both local control , by either surgery , radiation or a combination of these , and systemic chemotherapy.5 with the advent of modern chemotherapy , the long term , 5-year survival rate has improved to approximately 70%.1112 with small soft tissue and bone sarcomas in the extremities , local control by surgery has been better than with primary radiotherapy .
patients with hand lesions are recorded to have survived for more than 41 months and european intergroup study data showed a 68% overall 3 year survival rates in patients with distal extremity lesions.5 because ewing 's sarcoma and related tumors occur so rarely in the hand , there are no standardized treatment recommendations .
based on current evidence , however , chemotherapy and wide local tumor resection should be considered the mainstays of treatment.6
the differential diagnosis of unusual finger swellings in children and the atypical radiographic picture this tumor should have high index of suspicion of ewing 's sarcoma .
it is important to bear in mind that the presence of metastases is the most important prognostic factor and thus the need for accurate early diagnosis . | ewing 's sarcoma is the second most common malignant primary bone tumor of childhood and adolescence affecting mainly the diaphysis of long bones and flat bones .
this tumor is extraordinarily rare in small bones of the hand and presents as a swelling with atypical radiological features of cystic and lytic lesion with scant periosteal reaction .
the common differential diagnosis include osteomyelitis , tuberculosis , enchondroma and benign tumors .
moreover , skip metastasis to adjacent bones is even rarer .
the prognosis of this condition is greatly influenced by the presence of metastasis at presentation , further emphasizing the importance of early diagnosis .
multimodality treatment using surgery , radiotherapy and chemotherapy is currently recommended though no consensus exists .
we report a case of ewing 's sarcoma of the little finger proximal phalanx which was initially missed and developed skip metastasis to several metacarpals within 4 months . |
in ni@xmath5mnga heusler alloy , a structural transformation from cubic austenitic to tetragonal martensitic phase is observed upon cooling .
the interest in the study of ni@xmath5mnga - based alloys has mainly been conditioned by the fact that the martensitic phase in these alloys is ferromagnetic .
the combination of ferromagnetic ordering and martensitic transformation allows realization of magnetically driven shape memory effect , which expands considerably the area of technical applications of this effect . despite a large number of experimental and theoretical studies ,
many fundamental aspects of ni@xmath5mnga - based alloys are not clearly understood yet .
for instance , magnetic properties of thoroughly studied ni@xmath0mn@xmath1ga system were not sufficiently clarified . for these alloys , the compositional dependencies of curie temperature @xmath6 and martensite - austenite transformation temperature @xmath7 were determined but the temperature and compositional dependencies of magnetization have been not investigated in details . in particular , no systematic study was performed on the jump of magnetization at martensitic transition , which determines the shift of @xmath7 under external magnetic field .
besides , the exchange interaction parameters have been not estimated for these alloys .
all these factors are important to get a better insight into physical mechanisms , underlying the magnetically driven shape memory effect .
this paper deals with a systematic study of magnetic properties of ni@xmath0mn@xmath1ga ( @xmath2 ) alloys .
the high - temperature austenitic phase of ni@xmath0mn@xmath1ga heusler alloys has a cubic structure of fm@xmath8 m space group . a structural transition to a modulated tetragonal ( @xmath9 )
phase is observed in these alloys on cooling .
it is worth noting that the crystal structure and space group of the low - temperature phase is still a subject of controversy ( see , for example , refs . ) which is aggravated by a compositional dependence of the crystal structure of martensite .
thus , for example , recent results of high - resolution neutron diffraction @xcite give ground to conclude that for the stoichiometric ni@xmath5mnga composition the martensitic phase , being considered for a long time as a tetragonal , has indeed an orthorhombic symmetry of pnnm space group . the structural martensitic transformation in ni@xmath5mnga - based heusler alloys
was described as driven by a band jahn - teller effect .
@xcite the martensitic transformation temperature @xmath7 , which is about 200 k in stoichiometric ni@xmath5mnga , linearly increases with @xmath10 in ni@xmath0mn@xmath1ga alloys and reaches about 330 k at @xmath11 ( ref . ) .
the alloys with a higher ni content were not studied so far .
note that different values of @xmath7 are given in literature , indicating probably the sensitivity of physical properties of these alloys to structural disorder @xcite and/or deviations from the nominal composition .
the ni@xmath0mn@xmath1ga alloys are ferromagnetic at low temperatures .
the curie temperature @xmath6 is about 370 k in stoichiometric composition ( @xmath12 ) .
@xmath6 approximately linearly decreases with increasing ni content , so that for @xmath13 curie temperature merges with the martensitic transformation temperature @xmath7 .
hence , the alloys with @xmath14 experience a structural ( martensitic ) transition from paramagnetic austenite to ferromagnetic martensite . at the same time , the magnetic state of the alloys with a lower ni content does not change during martensitic transformation and both austenitic and martensitic phases are ferromagnetic .
the martensitic transformation , however , influences the magnetic parameters of these alloys and reveals itself in a sharp change of magnetic anisotropy and magnetization saturation .
@xcite the neutron diffraction measurements of stoichiometric composition @xcite show that the magnetic moment is localized mainly on mn atoms .
the reported values of the mn magnetic moment range from 3.8 to 4.2 @xmath15 .
the magnetic moment of ni atoms is considerably smaller , about 0.2 - 0.4 @xmath15 .
the concentration dependence of magnetic moment in ni@xmath0mn@xmath1ga alloys has been not reported .
it is known only that magnetization saturation decreases with increasing @xmath10 .
polycrystalline samples of ni@xmath0mn@xmath1ga alloys were prepared by a conventional arc - melting method in the atmosphere of spectroscopically pure argon gas .
the samples were homogenized at 1050 k for 9 days with subsequent quenching in ice water . for the measurements of physical properties
those samples were used whose weight loss during arc - melting was less than 0.2% .
the measurements of magnetic properties were performed on samples with @xmath10 = 0 , 0.04 , 0.08 , 0.12 , 0.16 , and 0.19 ; some measurements were also done on the sample with @xmath16 .
the magnetization up to 5 t was measured in a temperature range 5 700 k by a squid magnetometer `` quantum design '' ; it was also measured by a vibrating sample magnetometer ( vsm ) in magnetic fields up to 1.8 t. additionally , measurements in pulsed magnetic fields up to 10 t were performed .
spontaneous magnetization @xmath17 at low temperatures was determined by linear extrapolation of @xmath18 dependencies from high fields .
@xmath17 in the vicinity of curie temperature , where @xmath18 dependencies are non - linear , was estimated by belov - arrott method for second - order magnetic phase transitions . using this method ,
the curie temperatures were determined for every alloys except the @xmath19 sample , where the ferromagnetic - paramagnetic transition is a first - order phase transition .
the paramagnetic susceptibility of the alloys was defined from @xmath20 dependencies measured above @xmath6 up to 700 k in a magnetic field of 0.2 t. the latent heat of martensitic transition was determined from differential scanning calorimetry , performed by a pyris-1 dsc equipment .
mn@xmath1ga alloys . ]
temperature dependencies of spontaneous magnetization @xmath17 of the ni@xmath0mn@xmath1ga alloys are shown in fig .
it is seen that @xmath17 gradually decreases with increasing temperature and exhibits a pronounced change ( smeared jump ) when approaching a certain temperature @xmath7 .
this jump in magnetization is caused , as has been shown in numerous studies , @xcite by a structural phase transition from martensite to austenite . as evident from these measurements ,
the austenitic phase is ferromagnetic above @xmath7 for @xmath21 , while in the @xmath19 alloy the transformation from martensite to austenite is accompanied by a transition from ferromagnetic to paramagnetic state .
the compositional dependence of the martensitic transformation temperature @xmath7 is shown in fig .
this figure also shows the dependence of ferromagnetic ordering temperature @xmath6 on ni content @xmath10 .
it is seen that both these dependencies are practically linear with @xmath7 increasing and @xmath6 decreasing with ni content .
these temperatures merge in a range of @xmath22 .
the phase diagram of the ni@xmath0mn@xmath1ga system obtained in the present study is in good agreement with previously found one .
@xcite the magnetic moment of these alloys , @xmath23 , was obtained by extrapolation of @xmath3 to 0 k. it was found that @xmath23 approximately linearly decreases at substitution of mn by ni , as is shown in fig .
the value of magnetic moment in the stoichiometric ni@xmath5mnga appears to be close to those reported in others studies .
@xcite the @xmath3 dependencies in ni@xmath0mn@xmath1ga alloys , shown in fig . 1 ,
evidence that the change of spontaneous magnetization at martensite - austenite transformation increases with ni content .
a jump of magnetization at this transition is also observed in magnetic fields larger than the saturation field , as is shown in fig .
the compositional dependencies of the magnitudes of magnetization jump @xmath4 measured in various magnetic fields are shown in fig .
5 . as can be seen from fig . 4 , with increasing magnetic field the magnetization jumps shift to higher temperatures .
this is due to the influence of magnetic field on martensitic transformation temperature .
it follows from these measurements that the shift @xmath24 of @xmath7 under magnetic field increases weakly with ni content ( see table 1 ) .
the influence of a magnetic field on the martensite - austenite transition temperature was studied only for @xmath12 ( ref . ) and @xmath14 ( refs . )
compositions . for the stoichiometric composition
the shift of @xmath7 under magnetic field was estimated as @xmath25 k / t .
@xcite for the @xmath26 and @xmath19 compositions , @xmath27 k / t was reported in refs . , whereas in ref .
this quantity was estimated as 3.5 k / t .
it is worth noting that the shift of @xmath7 is determined with a significant error .
this is caused mainly by the fact that the jump of magnetization at martensitic transformation is broad which makes difficult correct determination of @xmath7 temperature .
besides , martensitic transformation is a first - order structural phase transition and is characterized by a temperature hysteresis .
therefore , @xmath7 temperature can differ from the temperature at which the jump of magnetization occurs .
the most correct method to determine @xmath7 is to determine this temperature as the average of the temperatures , at which magnetization jump is observed on cooling and heating , respectively . in the present study , @xmath7 was determined as a temperature of the magnetization jump while heating the sample .
the temperature hysteresis loop was measured for the @xmath19 sample .
it was found ( see fig .
4 ) that @xmath7 determined at increasing temperature differs from @xmath7 estimated from averaging of measurements in hysteretic regime by 23 k. the width of the temperature hysteresis loop is approximately the same in different magnetic fields , so the additional error in determination of the shift of @xmath7 caused by a magnetic field does not exceed 0.3 k. .theoretical and experimental values of the shift @xmath28 of the martensitic transition temperature @xmath7 in a magnetic field @xmath29 = 2 t for ni@xmath0mn@xmath1ga . [ cols="^,^,^,^,^,^ " , ] note that these calculations are based on assumptions that the magnetic moments of constituting atoms does not change with deviations from stoichiometry and that the ni atoms possess similar moments in different crystallographic sites . in general this is not the case , because magnetism of heusler alloys is described in a band model .
it means that the values of magnetic moments depend on density of states at fermi level and on the exchange splitting parameter , being therefore the concentration and structure dependent values . as has been noted in ref .
, in ni@xmath5mnx heusler alloys the distance between the atoms is sufficiently large so that direct overlap of electron orbitals is negligible and the delocalization effects are of secondary importance .
therefore , in the first approximation a localized moments model is applicable for the description of magnetic properties of these alloys .
however , from the results of magnetic and nuclear magnetic resonance measurements of ni@xmath5mnga @xcite it was concluded that in this alloy the mn magnetic moments are mainly localized , while ni magnetic moments are essentially delocalized .
the character of magnetism can be judged from the comparison of the magnetic moments of the constituting atoms and their effective magnetic moments ( see table 2 ) . in the model of localized magnetic moments for the spin - only state ( orbital moment
is quenched ) the interrelation between effective magnetic moment and the moment in the magnetically ordered state is given by wohlfarth - rhodes equation @xmath30 in the band model the value of @xmath31 calculated from eqn .
( 3 ) should be smaller than the experimental value of the effective moment due to the influence of delocalization effects .
the values of @xmath31 for the mn and ni subsystems are given in table 2 .
as evident from these data , for both mn and ni subsystems @xmath32 and @xmath31 are close to each other , although in both cases @xmath31 is slightly smaller than @xmath32 . within the experimental error of the measurements
the @xmath33 ratio is the same for both mn and ni subsystems .
thus , present experimental data do not suggest that the ni subsystem is more delocalized that the mn one . it should be understood , however , that the magnetic moments in the magnetically ordered state were determined in the martensitic phase , whereas the effective magnetic moments were calculated from the paramagnetic susceptibility measured in the austenitic state .
it makes no difference if magnetism is described in the localized model , because in this case the magnitude of magnetic moment depends weakly on the crystallographic environment . in the band model ,
magnetic moments depend on the degree of overlap of electron orbitals , which changes at structural transformation . because of this
, a possibility that the magnetic moments will change at structural transition must not be ruled out .
the qualitative arguments given above are supported by the experimental data reported in ref . , which indicate that the magnetic moment of mn is the same in austenitic and martensitic phases , whereas magnetic moment of ni in austenitic phase is larger than that in the martensitic phase .
the latter observation is conditioned by a higher density of states of ni at the fermi level in austenitic state than that in the martensitic state , as electronic structure calculations have revealed .
@xcite as evident from fig . 2 , curie temperature of the austenitic phase decreases at substitution of mn for ni .
this is due to the fact that this substitution leads to an increase in the number of atoms with smaller magnetic moments .
similar tendency takes place presumably for a virtual curie temperature of the martensitic phase .
this follows from the observation that in the low - temperature martensitic phase magnetization of the ni@xmath0mn@xmath1ga alloys with a higher @xmath10 decreases more rapidly with increasing temperature .
the magnetization data shown in fig . 1 allow estimation of virtual curie temperature of the martensitic phase .
8 shows temperature dependencies of reduced spontaneous magnetization @xmath34 of the alloys as a function of reduced temperature @xmath35 .
it is seen that the magnetization of austenitic phase and the magnetization of martensitic phase change with temperature in different way , whereas the reduced magnetizations of these phases are similar for different compositions .
it can be assumed that the difference in @xmath36 of martensite and austenite is due to the difference in their curie temperatures . comparing @xmath36 dependencies of martensitic and austenitic phases ,
it is possible to reconstruct the virtual curie temperature of martensitic phase , which is shown by the solid line in fig .
it appears to be 17% higher than the curie temperature of austenitic state .
this value is twice as large as that obtained from phenomenological landau theory .
@xcite as a function of reduced temperature @xmath37 for the ni@xmath0mn@xmath1ga alloys .
the solid line is reduced magnetization of virtual martensitic phase.,width=264 ] the larger value of curie temperature of martensite as compared to curie temperature of corresponding austenite is due to changes in interatomic distances and in overlap of electronic orbitals . as evident from the analysis of experimental data ,
this effect can not be attributed solely to a change in the unit cell volume at martensitic transformation .
indeed , a study of the influence of hydrostatic pressure on curie temperature @xmath6 and martensitic transformation temperature @xmath7 of stoichiometric ni@xmath5mnga @xcite has shown that the exchange interaction of the austenite increases with decreasing unit cell volume .
at the same time , it is known @xcite that the unit cell volume of martensite is larger than that of austenite .
therefore , it seems likely that the primary role in martensitic transformation in ni@xmath5mnga heusler alloys belongs to the crystal lattice distortions .
such a mechanism of the influence of a structural transition on exchange interaction in intermetallic compounds gd@xmath38(si@xmath39ge@xmath1)@xmath40 was discussed recently in ref . .
as evident from fig . 5
, the magnitude of magnetization jump @xmath4 at structural transition strongly increases with ni content .
this is caused by the fact that the increase of @xmath10 leads to the increase of @xmath7 . under these circumstances , the difference between magnetizations of martensite and austenite at @xmath7 increases as well .
it is also seen from fig . 5 that the magnetization jumps @xmath4 at @xmath7 diminishes at increasing magnetic field , which is the most pronounced at high @xmath10 .
the behavior of @xmath4 in the alloys with a small @xmath10 results from the fact that the martensitic transformation in these alloys occurs at temperatures far below curie temperature @xmath6 and therefore the influence of a magnetic field on magnetization is weak . in the alloys with a large @xmath10
, @xmath7 is close to @xmath6 of the austenitic phase and the external field strongly affects magnetization of this phase , whereas magnetization of the martensitic phase depends weakly on the magnetic field .
it has been already mentioned that the temperature of structural transition shifts to higher temperatures upon application of a magnetic field .
such behavior is governed by the influence of zeeman energy , which stabilizes martensitic phase with a larger magnetization .
experimental data on the shift of @xmath7 are presented in table 1 .
these results indicate that for the alloys studied the shift is rather small ( 12 k as the magnetic field changes for 2 t ) and slightly enhances with increasing ni content .
the table also contains theoretical estimation of the shift of @xmath7 in magnetic field , derived from a thermodynamical clapeyron - clausius relation for first - order phase transitions : @xmath41 the agreement between experimental and theoretical values can be considered as satisfactory .
this study was supported by rfbr grants no .
02 - 02 - 16636 and 03 - 02 - 17443 .
work at argonne was supported by us department of energy , bes materials sciences under contract w-31 - 109-eng-38 .
one of the authors ( vvk ) gratefully acknowledges the japan society for the promotion of science for a postdoctoral fellowship award .
a. d. bozhko , a. n. vasilev , v. v. khovailo , i. e. dikshtein , v. v. koledov , s. m. seletskii , a. a. tulaikova , a. a. cherechukin , v. g. shavrov , and v. d. buchelnikov , zh .
teor . fiz . *
115 * , 1740 ( 1999 ) [ jetp * 88 * , 954 ( 1999 ) ] . | a systematic study of magnetic properties of ni@xmath0mn@xmath1ga ( @xmath2 ) heusler alloys undergoing structural martensite - austenite transformations while in ferromagnetic state has been performed . from measurements of spontaneous magnetization , @xmath3 , jumps @xmath4 at structural phase transitions were determined .
virtual curie temperatures of the martensite were estimated from the comparison of magnetization in martensitic and austenitic phases . both saturation magnetic moments in ferromagnetic state and effective magnetic moments in paramagnetic state of mn and
ni atoms were estimated and the influence of delocalization effects on magnetism in these alloys was discussed .
the experimental results obtained show that the shift of martensitic transition temperature depends weakly on composition .
the values of this shift are in good correspondence with clapeyron - clausius formalism taking into account the experimental data on latent heat at martensite - austenite transformations . |
since 1976 , the rssler system @xcite is well know for it s simplicity ( three differential equations with only one non linear term ) and its dynamical richness producing chaos .
used as a basic system to demonstrate various properties of dynamical systems , this system is still a source inspiration for researchers .
this system has been widely explored with several tools .
the main goal of this paper is to extend the use of the topological characterization method to several chaotic attractors .
we introduce a way to use the template as a global description that contains various attractors templates of the rssler system . in this paper
, we will study this system in a parameter space to highlight common properties of neighbours attractors in this space .
@xcite study of the parameter space of this system using lyapunov exponents reflects its dynamics ( stable , chaotic or trajectory diverging ) .
the maps are built varying parameters @xmath0 and @xmath1 of the system .
these maps display fractal structure and illustrate period doubling cascades .
this principle is also employed by barrio _
@xcite for the three parameters of the rssler system .
their analysis of local and global bifurcations of limit cycles permits to a have a better understanding of the parameter space .
additionally , attractors with equilibrium points associated to their first return maps are also plotted to illustrate the various dynamics of this system , including coexistence of attractors . to enlarge this overview of recent work on the bifurcations and dynamics on the rssler system , genesio _ et al .
_ @xcite use the first - order harmonic balance technique to study fold , flip and neimark - sacker bifurcations in the whole parameter space . finally , the recent work of sprott & li @xcite introduce another way to reach coexisting attractors in addition to the cases identified by barrio _
_ @xcite . in this paper
we study a bifurcation diagram of the rssler system exhibiting various dynamics using topological properties of attractors .
we use the topological characterization method based on the topological properties of the attractor s periodic orbits @xcite .
the purpose is not only to obtain templates of chaotic attractors but also to find common points or properties as it as already been shown for this system by letellier _
@xcite for a `` funnel attractor '' . in this particular case
, a linking matrix describes the template depending on the number of branches . in this paper
, we will explore a bifurcation diagram and show that only one template contains all the templates of attractors as subtemplates .
this paper is organized as follow .
the first part introduces the sprott & li @xcite work with their bifurcation diagram .
the second part details the topological characterization method ; height attractors are studied and their templates are obtained .
then we prove that the eight templates are subtemplates of a unique template .
it describes the topological structure of all the attractors of the entire bifurcation diagram .
finally we provide a partition of the bifurcation diagram giving the symbolic dynamic associated with the unique template depending on the bifurcation parameter .
barrio _ et al . _ @xcite highlight the fact that a rssler system can have to coexisting attractors as solutions for a set of parameters .
sprott & li @xcite parametrize the rssler system @xcite with the parameter @xmath2 @xmath3 in order to explore bifurcations .
when @xmath4 , two attractors coexist in the phase space .
we reproduce their bifurcation diagram when @xmath2 varies .
the value of the fixed points of the system are @xmath5 \displaystyle y_\pm = \frac{-c\mp \sqrt{c^2 - 4ab}}{2a } \\[0.3 cm ] \displaystyle z_\pm = \frac{c \pm \sqrt{c^2 - 4ab}}{2a } \ , .
\end{array } \right .
\label{eq : rossler_fixed_point}\ ] ] the bifurcation diagram fig .
[ fig : rossler_bifurcation ] is obtained using the following poincar section @xmath6 where @xmath7 is the @xmath8 value of the fixed point @xmath9 ( see @xcite for details on this poincar section ) .
the uses of this poincar section explains why fig .
[ fig : rossler_bifurcation ] is similar to fig .
4 of @xcite : we use @xmath10 and they use @xmath11 which is a local maximum of @xmath8 . consequently , in both case , values close to zero correspond to value close to the center of the attractor and oppositely , high absolute values correspond to the outside boundary of the attractor .
varies : @xmath2 increasing ( red ) and @xmath2 decreasing ( black ) .
this figure reproduces the fig . 4 of @xcite . using @xmath2 increasing or decreasing replaces different initial conditions used in the original paper @xcite .
@xmath12 , @xmath13 , @xmath14 , @xmath15 , @xmath16 , @xmath17 , @xmath18 and @xmath19 refers to attractors solutions with the parameters indicated in . ]
this diagram indicates parameter for the rssler system where the solution is a limit cycle or chaotic .
this diagram exhibits a doubling period cascade that is a classical route to chaos for @xmath20 .
this is followed by a chaotic puff ( @xmath21 ) and by various regimes ( banded chaos and almost fully developed chaos ) .
we chose representative values of @xmath2 where one ore two attractors are solutions of the system @xmath22 we analyse these attractors using topological characterization method in order to obtain a generic description of the attractors while @xmath2 is varied .
the main purpose of the topological characterization method is to build a template using topological properties of periodic orbits .
the template has been introduced by @xcite further to the works of poincar @xcite . according to ghrist _
@xcite , a template is a compact branched two - manifold with boundary and smooth expansive semiflow built locally from two type of charts : joining and splitting .
each charts carries a semiflow , endowing the template with an expanding semiflow , and the gluing maps between charts must respect the semiflow and act linearly on the edges .
this topological characterization method is detailed by gilmore & lefranc @xcite .
recently , we detail additional conventions to obtain templates that can be compared and sorted @xcite .
we start with a brief description of the method .
as the trajectories are chaotic , they are unpredictable in a long term behavior . but attractors have a time invariant global structure where its orbits compose its skeleton .
the purpose of the method is to use the topological properties of these orbits to describe the structure of the attractor .
we provide a sum up of this method with eight steps ( including our conventions ) : 1 .
display the attractor with a clockwise flow ; 2 .
find the bounding torus ; 3 .
build a poincar section ; the first step permits to ensure that the study will be carried out to the respect of conventions : clockwise flow having a clockwise toroidal boundary and described by a clockwise template .
this clockwise convention ensures us to describe template with a unique linking matrix , a keystone to work only with linking matrices @xcite .
the toroidal boundary give a global structure that permit to classify attractors .
for a given toroidal boundary , a typical poincar section is associated according to the tsankov & gilmore theory @xcite .
this poincar section contains one or more components to permit an effective discretization of trajectories and consequently an efficient partition of the attractor . 1 .
compute the first return map and define a symbolic dynamic ; 2 .
extract and encode periodic orbits ; 3 .
compute numerically the linking numbers between couple of orbits ; the first return map details how two consecutive crossings of a trajectory through the poincar section are related and permits to associate a symbol to each point .
it permits to define a partition of the attractor and a symbolic dynamic .
associated symbols depend on the parity of the slope ( even for the increasing one , odd for the other ) . up to this point ,
periodic orbits structuring the attractor are extracted and encoded using this symbolic dynamic .
the linking number between a pair of orbits is a topological invariant indicating how orbits are wind one around another . in this paper
, we use the orientation convention of fig .
[ fig : convention ] . [ cols="^,^,^,^,^,^ " , ] as we do previously , we decompose this subtemplate ( fig .
[ fig : rossler_f_subtemplate]b ) in parts : the two parts contain a mixer and these parts permute negatively once .
thus , we concatenate a mixer before a mixer and two negative torsions ( cf .
[ ssec : banded ] ) .
the first concatenation gives a mixer defined by a linking matrix ; the algebraical relation necessary to obtain this matrix are detailed in @xcite .
the linking matrix of @xmath23 as a subtemplate ( fig .
[ fig : rossler_f_subtemplate]a ) is : @xmath24 \\ \quad = \left[\left| \begin{array}{c{1.3em}c{1.3em}c{1.3em}c{1.3em } } -1 & -1 & -1 & -1 \\
-1 & -1 & -1 & -1 \\
-1 & -1 & 0 & 0 \\ -1 & -1 & 0 & 0 \end{array}\right| + \left| \begin{array}{c{1.3em}c{1.3em}c{1.3em}c{1.3em } } 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \end{array}\right| + \left| \begin{array}{c{1.3em}c{1.3em}c{1.3em}c{1.3em } } -1 & -1 & -1 & -1
\\ -1 & 0 & 0 & -1 \\
-1 & 0 & 0 & -1 \\
-1 & -1 & -1 & -1 \end{array}\right| \right\rsem + [ -2 ] \\
\quad = \left [ \begin{array}{c{1.3em}c{1.3em}c{1.3em}c{1.3em } } -2 & -2 & -2 & -2 \\
-2 & -1 & -1 & -1 \\
-2 & -1 & 0 & -1 \\
-2 & -1 & -1 & -1 \end{array}\right\rsem + [ -2 ] % \\
= % \quad = \left [ \begin{array}{c{1.3em}c{1.3em}c{1.3em}c{1.3em } } -4 & -4 & -4 & -4 \\
-4 & -3 & -3 & -3 \\
-4 & -3 & -2 & -3 \\
-4 & -3 & -3 & -3 \end{array}\right\rsem = t(\mathcal{f } ) \end{array}\ ] ] this algebraical relation between template and subtemplate linking matrices associated to fig .
[ fig : rossler_f_subtemplate ] prove that @xmath25 .
we now consider the attractor @xmath15 , we have @xmath26 directly from their mixers @xmath27 this is illustrated on fig .
[ fig : rossler_d_subtemplate ] .
we previously obtain that @xmath28 , thus we prove that @xmath29 .
is a subtemplate of the template of @xmath18 and consequently , it is also a subtemlate of the template of @xmath14 . ]
consequently , we prove that the six templates of attractors @xmath12 , @xmath13 , @xmath15 , @xmath16 , @xmath17 and @xmath18 are subtemplate of the template of the attractor @xmath14 ; it is a template with six subtemplates .
we remind that @xmath19 and @xmath14 have the same template ( @xmath30 ) .
we obtain a unique template containing the eight templates of attractors .
we now consider the whole bifurcation diagram ( fig .
[ fig : rossler_bifurcation ] ) and not only specific attractors . in this section
, we will show that the template of @xmath14 contains all attractors templates for any parameter value take from this bifurcation diagram .
we use the poincar section and build return maps using @xmath10 for @xmath31 - 2;1.8[$ ] when an attractor is solution .
we associate a symbolic dynamic with the three symbols `` @xmath32 '' , `` @xmath33 '' , `` @xmath34 '' of @xmath35 .
note that barrio _
_ @xcite also use this process to study return maps of a rssler system from a lyapunov diagram .
the authors display return maps with superstability curve and coexisting stable points . here
we prefer collect extrema points to make a partition of the bifurcation diagram .
varies build using first return maps on @xmath10 of the poincar section .
this partition give a symbolic dynamic with three symbols `` @xmath32 '' , `` @xmath33 '' , `` @xmath34 '' depending on @xmath2 . ] in the diagram fig .
[ fig : rossler_bifurcation_symbolic ] , we indicate the values of @xmath10 splitting the return maps into two or three parts . we remind the reader that we orientate application from the inside to the outside of the attractor .
thus , the branches are labelled with symbol number increasing while @xmath10 decrease .
[ fig : rossler_bifurcation_symbolic ] reveals that the separator values are linear to @xmath2 .
we note @xmath36 the value of @xmath10 that split branches `` @xmath32 '' and `` @xmath33 '' and @xmath37 the value of @xmath10 that split branches `` @xmath33 '' and `` @xmath34 '' .
a linear regression gives @xmath38 up to this point , if there is an attractor solution , its orbits can be encoded with the symbols depending on the previous equations .
this also requires the use of the poincar section . for a given range of a bifurcation parameters ( @xmath31 - 2;1.8[$ ] ) ,
the parameters of the rssler system depends on @xmath2 : @xmath39 , @xmath40 and @xmath41 .
the fixed points depend on the parameters and the poincar section depend on the fixed points .
thus , we obtain a poincar section and its partition depending on @xmath2 while the template is define by the linking matrix @xmath42 the main result is that the topological characterization of chaotic attractors can be extended as a description of various attractors whose parameters come from one bifurcation diagram . in this bifurcation diagram , we show that there are regimes where the chaotic mechanisms are topologically equivalent ( @xmath43 ) , symmetric ( @xmath44 and @xmath45 ) and they are a subset of the same chaotic mechanism .
the point is that our work can help to understand the complex structure of attractors considering them as subtemplates of their neighbors ( in term of bifurcation parameter ) .
this also enlarge the possibility to use the topological characterization to describe more than an attractor , but an entire bifurcation diagram .
in this paper we study eight attractors of the rssler system .
the parameters values of these attractors come from a bifurcation diagram that exhibits various dynamics such as coexisting attractors . for each attractor
we apply the topological characterization method that give us a template of the attractor .
these templates detail the chaotic mechanism and these are only made of stretching and folding mechanism followed by a squeezing mechanism with two , three and four strips .
the second part of this paper is dedicated to the proof that the eights templates are subtemplates of a unique template : the template of @xmath14 .
the main result here is that a template is no longer a tool to describe one attractor but also a set of neighbours attractors ( in the parameter space ) .
thus for a bifurcation diagram , we build a partition using symbols of @xmath35 .
this partition over the whole diagram give a global structure of attractors for a range of parameters .
this better understanding of the structure of bifurcation diagram can help researchers that want to explore the behaviour of their system , especially if it exhibits chaotic properties .
for instance matthey _
@xcite design a robot using coupled rssler oscillators to simulate its locomotion .
a similar theoretical analysis of their system can provide various set of parameters with specific chaotic properties that might induce new locomotion pattern .
a partitioned bifurcation diagram details the various non equivalent dynamical behavior of the system to find them .
this work on templates of attractors from a unique bifurcation diagram is a first step that can lead to a description of manifolds using templates .
it is also a new way to classify templates grouping them as subtemplates and not claiming that it exists six new attractors for the rssler system .
to conclude , this work permits to apply the topological characterization method to a set of attractors from a bifurcation diagram .
the partition of a bifurcation diagram associated with a unique template is a new tool to describe the global dynamical properties of a system while a parameter is varied . in future works
, we will apply this method on attractors bounded by higher genus torus to highlight how symmetry breaking or template number of branches are related in a bifurcation diagram .
00 rosalie m and letellier c 2013 systematic template extraction from chaotic attractors : i - genus - one attractors with an inversion symmetry _ journal of physics a : mathematical & theoretical _ * 46*(37 ) 375101 rosalie m and letellier c 2015 systematic template extraction from chaotic attractors : ii .
genus - one attractors with multiple unimodal folding mechanisms _ journal of physics a : mathematical & theoretical _ * 48*(23 ) 235101 matthey l , righetti l and ijspeert a j 2008 experimental study of limit cycle and chaotic controllers for the locomotion of centipede robots , _ intelligent robots and systems , 2008 .
iros 2008 .
ieee / rsj international conference on . ieee _ | we study the bifurcation diagram of the rssler system .
it displays the various dynamical regimes of the system ( stable or chaotic ) when a parameter is varied .
we choose a diagram that exhibits coexisting attractors and banded chaos .
we use the topological characterization method to study these attractors .
then , we details how the templates of these attractors are subtemplates of a unique template .
our main result is that only one template describe the topological structure of height attractors .
this leads to a topological partition of the bifurcation diagram that gives the symbolic dynamic of all bifurcation diagram attractors with a unique template .
_ keywords _ : rssler system , bifurcation diagram , template , subtemplate |
systems coupled to multiple energy reservoirs , sustaining net transport currents , are prevalent in nature but fall outside the fundamentally well - understood paradigms of equilibrium statistical mechanics .
the characterization and classification of such systems , starting from simple microscopic models , remains a key problem of current research . since steady states in such systems
constitute the closest relatives of equilibrium ( gibbs ) states , their study has attracted much recent attention @xcite , revealing a wealth of unexpected phenomena , even in simple model systems .
one of the prime , and most elementary , examples of this kind is a system of hard - core particles undergoing biased diffusion . with appropriate boundary conditions , this system , also known as
the simple asymmetric exclusion process ( asep ) @xcite , can exhibit a number of surprising features , including anomalous diffusion @xcite , long - range spatial correlations @xcite , and shocks @xcite . one of its key characteristics is the breaking of the usual fluctuation - dissipation theorem @xcite . in the following , we will discuss the effect of long - range correlated noise on this model , formulated via a langevin equation in continuous space and time .
generated , for example , by correlated fluctuations in the strength of the bias , the additional operator acts in the one - dimensional subspace ( labelled * * `` longitudinal '' ) selected by the bias .
its momentum dependence takes the form @xmath2 , with @xmath3 .
the two extreme values , @xmath4 and @xmath5 , are of particular interest .
the choice @xmath4 corresponds to the standard asep .
in contrast , @xmath5 leads to a langevin equation with _ non - conserved _ noise , describing biased diffusion of particles which can occasionally be created or annihilated . first introduced by hwa and kardar @xcite as a continuum description for sliding avalanches in sandpile models , it was analyzed in more detail by becker and janssen @xcite .
the key advantage of the correlated noise term is that it allows us to capture the _ crossover _ between these two models , characterized , respectively , by conserved and non - conserved noise .
thus , using field theoretic techniques , we discuss the full renormalization group ( rg ) flow in @xmath6 space , for @xmath7 . while the limit @xmath8 presents no difficulties , the opposite limit @xmath9 is far more subtle : we will see that , just below the upper critical dimension @xmath10 , _ two _ nontrivial renormalizations are required to render the @xmath4 theory finite , in contrast to a _
one if @xmath11 is positive and of @xmath12 , leading to an apparent discontinuity in the critical exponents .
a similar situation arises in standard @xmath13-theory with long - ranged interactions @xcite .
there , however , the discontinuity is entirely spurious and can be removed : letting @xmath14 denote the distance from the upper critical dimension of the short - range theory , the key is to recognize @xcite that there is a region of _ small _ @xmath15 , where a careful analysis of the rg flow reveals a smooth crossover between the @xmath4 and the @xmath16 theories .
thus , all universal scaling properties are shown to depend continuously on @xmath11 and @xmath17 . here
, in contrast , the limit @xmath18 is even more intricate : while the short - range theory is controlled by two fixed points , only a single one remains in the long - range model .
thus , only one of the two short - range fixed points is smoothly connected to the long - range fixed point , leading to a continuous crossover .
the other short - range fixed point eventually loses its stability , accompanied by a discontinuity in critical exponents . a second feature of our model concerns its close relationship to the kpz @xcite or burgers @xcite equation with correlated noise @xcite .
it is well known that the continuum description for the asep and the noisy burgers equation coincide in one spatial dimension .
in contrast to the burgers equation , the @xmath19-expansion for biased diffusion around @xmath20 presents no difficulties , and numerous results can be obtained exactly , to all orders in perturbation theory .
these may therefore be analytically continued to @xmath21 and are expected to hold for both , the asep and the kpz equation . in fact , to the extent that exact solutions @xcite are available , this expectation is indeed confirmed .
thus , our analysis bears some relation to the behavior of the one - dimensional burgers equation with correlated noise .
this paper is organized as follows .
we first introduce the langevin equation for the `` short - range '' ( sr ) version of our model , corresponding to the usual @xmath17-dimensional asep with translational invariance .
we then add a second noise term with long - range spatial correlations and propose two possible microscopic mechanisms for such a term . turning to the rg analysis
, we first summarize the sr case , @xmath4 .
the `` long - range '' ( lr ) theory associated with @xmath22 is presented next , and the limit @xmath8 is discussed .
finally , we introduce the `` hybrid '' model , characterized by @xmath15 , which interpolates between the sr ( @xmath4 ) and lr ( @xmath22 ) theories .
its rg flow is computed in a double expansion , where both @xmath23 and @xmath19 are small parameters .
the different fixed points are interpreted and their stability is evaluated , illustrating how the subtle crossover from @xmath4 to @xmath22 occurs . we conclude with some comments and open questions .
we consider a @xmath17-dimensional system of hard - core particles , which are allowed to diffuse on a regular lattice with fully periodic boundary conditions .
the bias , reminiscent of an electric field @xmath24 acting on charges , favors particle moves along a specific ( `` longitudinal '' ) direction along unit vector @xmath25 .
the long - time , long - wavelength properties of this model are most conveniently captured by a coarse - grained description in continuous space and time . here , only a single slow variable is needed , namely , the local particle density @xmath26 .
since the associated langevin equation has been discussed previously @xcite , we describe it only briefly here . due to particle number conservation
, it takes the form of a continuity equation , @xmath27 .
in addition to a diffusive term , the current @xmath28 contains an ohmic contribution , @xmath29 , induced by the bias , and a gaussian noise term , modelling the fast degrees of freedom . by virtue of the excluded volume constraint ,
the conductivity @xmath30 must vanish with both particle and hole density , i.e. , @xmath31 . aiming for a perturbation expansion around a field with zero average
, we introduce the deviations @xmath32 from the average density @xmath33
. a term linear in @xmath34 , arising from the expansion of @xmath30 , can be absorbed via a galilei transformation .
finally , we allow for anisotropies in the diffusion coefficient and the correlations of the langevin noise , since the bias singles out a preferred direction . neglecting contributions that are irrelevant in the long - wavelength , long - time limit
, the langevin equation can be summarized in the form @xcite : @xmath35 here , @xmath36 ( @xmath37 ) denote the gradients in the transverse ( longitudinal ) subspace , and the kinetic coefficient @xmath38 defines a time scale .
the coupling @xmath39 captures the effects of the drive .
the noise @xmath40 is gaussian so that two moments suffice to characterize its full distribution ( after a suitable rescaling of the variables ) : @xmath41 the differential operator @xmath42 in the second moment ensures that the conservation law is strictly obeyed .
clearly , the correlations described by this form are purely local , so that we will refer to eqns .
( [ le],[srn ] ) as the `` short - range '' ( sr ) theory .
its universal properties have been discussed in @xcite .
the simplest way of introducing a correlated noise into this equation is to _ add _ a long - range correlated noise to the local one .
thus , eqn .
( [ srn ] ) is amended to @xmath43 \delta \left ( { \bf r}-{\bf r}^{\prime } \right ) \delta \left ( t - t^{\prime } \right ) .
\label{lrn}\end{aligned}\ ] ] the new operator @xmath44 reflects a power - law decay of the noise correlations in real space , giving rise to a @xmath45 momentum dependence in fourier space .
clearly , setting @xmath11 to zero reproduces the sr theory , albeit with @xmath46 replaced by @xmath47 .
in contrast , choosing @xmath5 generates a non - conserved noise , playing the role of a random source term in eqn .
( [ le ] ) .
note that the vanishing of the first moment ensures that the particle density , while not strictly invariant under the dynamics , remains conserved _ on average_. the long - time , long - wavelength behavior of this theory has been analyzed in @xcite .
other choices of long - ranged noise correlations are of course possible @xcite .
the version adopted above is `` minimal '' in the sense that , first , it leads to a nontrivial , renormalizable theory , and second , it allows us to discuss the full crossover between the conserved ( @xmath4 ) and non - conserved ( @xmath48 ) cases using just one additional operator .
microscopically , such long - ranged contributions to the langevin noise can be generated in two ways : one option is to impose a bias which consists of a spatially uniform and a locally random component , with the latter controlled by a distribution with long - range correlations .
alternatively , one can retain the strictly uniform bias but randomly add or remove particles , according to a long - ranged distribution .
more details will be presented in @xcite . due to the presence of the nonlinearity , the computation of averages over the noise distribution requires a perturbative approach , coupled with renormalization group methods . for these purposes ,
it is most convenient to recast the langevin equations as dynamic functionals @xcite . introducing a martin - siggia - rose @xcite response field @xmath49
, we can recast eqns .
( [ le],[lrn ] ) in the form @xmath50 & = & \int dt\int d^{d}r\left\ { \tilde{s}% \partial _ { t}s-\lambda \tilde{s}\left [ \left ( \nabla _ { \bot } ^{2}+\rho \partial ^{2}\right ) s+\frac{g}{2}\partial s^{2}\right ] \right .
\nonumber \\ & & \left .
+ \lambda \tilde{s}\left [ \left ( \nabla _ { \bot } ^{2}+\sigma \partial ^{2}\right ) -b\left ( -\partial ^{2}\right ) ^{1-\alpha } \right ] \tilde{s}% \right\ } \label{df}\end{aligned}\ ] ] so that correlation and response functions can be computed as functional averages with weight @xmath51 .
we stress that the sr model is recovered from this general expression , simply by setting @xmath52 . as a first step towards the rg analysis of this model , we discuss its scaling symmetries .
first , under a global rescaling of all coordinates , @xmath53 , we find a scale invariant theory * * ( as long as we neglect any cutoff - dependence ) provided @xmath54 , @xmath55 and @xmath56*. * moreover , we obtain @xmath57 which allows us to identify the upper critical dimension @xmath58 . to avoid confusion , we will reserve the symbol @xmath19 for the sr case , i.e. , @xmath59 . for the general case ,
we define @xmath60 .
second , we may rescale the parallel coordinate alone , due to the anisotropy of the model : under @xmath61 , scale invariance is retained if @xmath62 , @xmath63 , @xmath64 , @xmath65 , @xmath66 and @xmath67 .
this permits us to identify a set of _ effective _ couplings , namely , @xmath68 , @xmath69 and @xmath70 .
these will emerge quite naturally in perturbation theory , combined with appropriate powers of @xmath71 which absorb the remaining momentum dependence . for convenience ,
a geometric factor @xmath72 , with @xmath73 the surface of the @xmath17-dimensional unit sphere , has been absorbed into @xmath74 . for later reference
, we note that only the positive octant @xmath75 and @xmath76 corresponds to physical theories even though the rg flow can be discussed in a larger parameter space .
finally , the dynamic functional ( [ df ] ) exhibits a nontrivial continuous symmetry , with parameter @xmath77 , which is characterized by the `` galilean '' transformation @xmath78 , @xmath79 .
so far , we were able to consider the case of general @xmath7 .
the next section will show , however , that this procedure can not be continued for the actual perturbative calculation of correlation and response functions .
we now turn to perturbation theory , with the goal of identifying those correlation and response functions that require renormalization , due to the presence of ultraviolet ( uv ) divergences in feynman diagrams . as usual , we focus on the one - particle irreducible ( 1pi ) vertex functions with @xmath80 ( @xmath81 ) external @xmath82- ( @xmath34- ) legs , @xmath83 .
these will be computed in dimensional regularization using minimal subtraction . since the models associated with @xmath4 and @xmath5 have been discussed previously ( in @xcite and @xcite , respectively )
, we only briefly summarize their rg structure , focusing predominantly on the theory with @xmath84 .
we first review the model with @xmath4 @xcite . here ,
the coupling @xmath85 and the effective @xmath86 are redundant and will be set to zero .
the upper critical dimension is @xmath87 .
straightforward dimensional analysis shows that there are three naively divergent vertex functions : @xmath88 , @xmath89 and @xmath90 . a ward identity based on the `` galilean '' symmetry shows , however , that @xmath90 requires no additional renormalization once @xmath91 and @xmath89
have been rendered finite . letting the superscript @xmath92denote bare couplings ,
the renormalized couplings are defined in the usual way : @xmath93 , @xmath94 , @xmath95 , where @xmath96 . the parameter @xmath71 sets a typical momentum scale which will control the rg flow .
all sr functions are marked with an explicit superscript to distinguish them from their finite @xmath11 counterparts .
the uv divergences in @xmath91 and @xmath89 give rise to nontrivial @xmath97-factors for @xmath98 and @xmath46 , which can be computed perturbatively in @xmath74 .
a one - loop calculation yields @xmath99 and @xmath100 .
we emphasize that @xmath101 is _ not _ treated perturbatively here ; therefore , @xmath102 fixed points for @xmath101 should not come as a surprise later .
finally , @xmath103 to all orders in @xmath74 , due to the `` galilean '' invariance . to complete the discussion
, we introduce the wilson functions @xmath104 the rg flow is expressed through the @xmath71-dependence of the renormalized couplings @xmath68 and @xmath105 , especially in the scaling limit @xmath106 : @xmath107 u , \nonumber \\ \beta _ { w}^{sr}\left ( u , w\right ) & \equiv & \left
. \mu \partial _ { \mu } w\right| _ { bare}=\biggl[\zeta _ { \rho } ^{sr}-\zeta _ { \sigma } ^{sr}\biggr]w . \label{srbf}\end{aligned}\ ] ] in this form , the right hand sides of eqn . ( [ srbf ] )
are exact to all orders .
these flow equations possess three fixed points , marked by the vanishing of both @xmath108 and @xmath109 : ( i ) @xmath110 , @xmath111 ; ( ii ) @xmath112 , @xmath113 ; ( iii ) @xmath114 , @xmath115 ; and finally a fixed line ( iv ) @xmath116 , with arbitrary @xmath101 .
the stability of these fixed points ( and line ) can be expressed through the @xmath117 matrix @xmath118 , @xmath119 , of derivatives of the @xmath120-functions , evaluated at the fixed points .
we find that the fixed line ( iv ) is stable only for @xmath121 , i.e. , @xmath122 , and will therefore be labelled a `` gaussian '' line .
focusing on @xmath123 , we find that ( i ) and ( ii ) are both locally stable .
fixed point ( iii ) is hyperbolic and sits on the separatrix @xmath124 which separates the domains of attraction of ( i ) and ( ii ) .
flow lines starting in the region @xmath125 are attracted towards fixed point ( i ) , and vice versa .
we refer to fixed point ( i ) as the fdt - restoring short - range fixed point , since theories with @xmath126 can be shown to possess a higher degree of symmetry , associated with satisfying the fdt @xcite . here ,
( [ srbf ] ) allows us to compute the fixed point values of @xmath127 and @xmath128 exactly , to all orders in @xmath19 : @xmath129 .
conversely , fixed point ( ii ) violates the fdt , and @xmath130 ; @xmath131 are known only perturbatively . finally , we comment briefly on the scaling properties associated with these fixed points @xcite , which arise from the rg equations for the vertex functions .
for example , the dynamic density correlation function ( structure factor ) @xmath132 scales as @xmath133 this reflects the emergence of anomalous diffusion , characterized , near fixed point ( i ) , by a strong anisotropy exponent @xcite @xmath134 , and , near fixed point ( ii ) by an exponent @xmath135 .
next , we turn to the case of finite @xmath11 .
as indicated in the introduction , we will have to distinguish between values of @xmath11 which are @xmath136 versus those which are @xmath137 . here , we analyze the second case , which corresponds to true long - range ( lr ) theories .
the first case , being a `` hybrid '' between short - range and long - range models , will be deferred to the next subsection .
recalling our discussion in section 2 , the critical dimension is now @xmath58 , and we define @xmath138 , to be distinguished from @xmath96 .
the operator @xmath139 is clearly irrelevant compared to @xmath140 and may be dropped .
the naive dimensions of the fields @xmath34 and @xmath82 are @xmath11-dependent , and as a result only _ two _ vertex functions , namely @xmath91 and @xmath141 , are naively divergent .
in contrast to the short - range case , @xmath142 is naively convergent here .
moreover , all divergent contributions to any vertex function are polynomial in the momenta @xcite , so that @xmath143 is not renormalized .
the `` galilean '' invariance still holds , so that @xmath90 , and hence @xmath144 , requires no new @xmath97-factor .
thus , defining renormalized couplings according to @xmath145 , @xmath146 , @xmath147 , we find @xmath148 to all orders , and @xmath149 , to first order in @xmath150 .
the latter is the appropriate effective coupling here , since @xmath46 no longer appears in the theory .
the coefficient @xmath151 controls the one - loop divergence in @xmath91 .
the wilson functions are easily obtained : @xmath152 and @xmath153 \bar{u}. \label{lrbf}\ ] ] clearly , the lr theory exhibits one ( gaussian ) fixed point @xmath154 which is easily shown to be stable above the upper critical dimension , and a nontrivial fixed point @xmath155 + o\left ( \bar{\varepsilon}% ^{2}\right ) $ ] , stable below @xmath156 . at this fixed point
, the value of @xmath157 is again known to all orders in @xmath158 , namely , @xmath159 .
the scaling properties of the long - range models are again easily derived from an rg equation for the vertex functions . for comparison with the sr case ,
we quote the result for the dynamic structure factor : @xmath160 once again , we observe anomalous diffusion ; here , however , it is controlled by the lr exponent @xmath161 .
it is obvious at this point that the limit @xmath18 , taken in the wilson function ( [ lrwf ] ) or the correlation function ( [ lrs ] ) , will not restore the sr theory .
first , @xmath162 which reproduces only the @xmath163 component of @xmath127 .
second , this naive limit can not generate a non - vanishing @xmath128 which plays a key role in the sr theory .
thus , not surprisingly , we do not observe a smooth crossover from the sr to the lr theory , by simply letting @xmath11 tend to zero in this naive fashion .
an elegant way of dealing with this difficulty was suggested in @xcite : by treating @xmath11 as a small parameter of @xmath164 and expanding in both @xmath19 and @xmath23 , one can `` magnify '' the small @xmath11-section of @xmath165 space and resolve the crossover between the sr and lr fixed points . concerning the scaling form of the structure factor , the prefactor @xmath166 originates entirely in the bare dimensions of the fields . since these are well defined under a naive @xmath9 limit ( cf .
section 2 ) and remain unrenormalized , we have @xmath167 without further complications .
the exponent @xmath168 , however , must be tracked much more carefully . before turning to these subtleties , we briefly consider the other limit , @xmath169 .
first , we summarize the @xmath5 theory @xcite , with @xmath170 , in its own right . here , @xmath143 measures the strength of the ( non - conserved ) noise .
the effective coupling is @xmath171 . according to @xcite ,
there is only one nontrivial @xmath97-factor , namely @xmath172 .
again , @xmath173 to all orders .
thus , the theories with @xmath5 and @xmath174 exhibit the same set of uv divergences . from the preceding discussion
, it is therefore clear that we may anticipate a smooth crossover here .
this is explicitly confirmed by the results of @xcite for @xmath5 : two fixed points @xmath154 and @xmath175 are found , stable above and below @xmath176 , respectively . at the nontrivial fixed point , @xmath177 takes the exact value @xmath178 .
it is easy to check that this agrees with the @xmath179 limit of eqns .
( [ lrwf]-[lrs ] ) , so that this limit is continuous . finally , we turn to the analysis of the key region in @xmath180 space , namely , @xmath15 .
the naive @xmath181 limit presupposes @xmath182 , and hence fails to resolve the crossover between the sr and lr theories which occurs for @xmath15 . with both @xmath11 and @xmath183 small , we follow @xcite and analyze the general dynamic functional , eqn .
( [ df ] ) , near the upper critical dimension of the sr theory , i.e. , @xmath184 . both couplings @xmath46 and
@xmath143 will be retained , and their rg flow will be studied .
we refer to this model as the `` hybrid '' theory , since it contains the vital elements of _ both _ sr and lr cases .
thus , the hybrid theory will exhibit a well - defined @xmath18 limit .
once again , we will be able to obtain a number of results to all orders in @xmath185 .
our first task will be to identify a set of suitable couplings which allow us to interpolate between the sr and the lr theories .
guided by @xcite , we consider the general structure of the wilson functions in the sr and the hybrid model .
the appropriate effective couplings will be those that map those functions onto one another . to obtain a general form for the wilson functions ,
we begin with the @xmath97-factors and construct them order by order in perturbation theory . focusing on the sr theory first , a typical graph of @xmath91 , at @xmath186-loop , contains @xmath187 vertices , @xmath186 ( bare ) correlators and @xmath188 ( bare ) propagators .
each vertex carries a factor of @xmath189 , and each correlator contributes a factor @xmath190 , where @xmath191 denote the frequency and momentum of the corresponding line .
symmetry requires that @xmath192 , out of the @xmath186 parallel momentum factors contributed by the vertices , will not be integrated over .
moreover , all denominators are generically of the form @xmath193 . changing the parallel integration variable from @xmath194 to @xmath195 , it is straightforward to show that such a graph will give rise to a contribution of the form @xmath196 in @xmath197 . here ,
the @xmath198 are the numerical coefficients of the @xmath199 poles , in minimal subtraction .
higher order poles appear also , of course , but cancel in the wilson functions and need not be considered for this reason .
generic @xmath186-loop graphs of @xmath89 have a similar structure , with @xmath200 correlators and @xmath201 propagators , and the coefficients of the lowest order @xmath19-poles will be denoted by @xmath202 here .
collecting , we obtain the @xmath97-factors in the general form : @xmath203 the general form of the wilson functions is easily found from the above : @xmath204 next , we consider the hybrid case .
two key differences emerge : first , each correlator now contributes a factor of @xmath205 to a given diagram .
this product gives rise to a sum of individual terms each of which contains @xmath206 factors of type @xmath207 and @xmath81 factors of type @xmath208 , with @xmath209 .
second , since @xmath11 is now of @xmath210 , the poles in these individual contributions are proportional to @xmath211 @xcite . following the same reasoning as above , and recalling the effective coupling @xmath70 ,
one finds quite readily that @xmath212 here , @xmath213 and @xmath214 are the numerical coefficients of each pole . in minimal subtraction , they are independent of both @xmath19 and @xmath23 , since the latter is also @xmath215 here .
clearly , the associated wilson functions take the form @xmath216 next , we establish a relationship between the coefficients @xmath217 and @xmath218 , by considering the @xmath18 limit of the hybrid theory .
in this limit , the dynamic functional , eqn .
( [ df ] ) , simply reduces to that of the sr theory , with @xmath46 replaced by @xmath47 .
therefore , we can relate @xmath219 and @xmath220 to @xmath197 and @xmath221 . due to the replacement of @xmath46 by @xmath47 , the sr @xmath97-factors depend on a modified set of couplings .
defining @xmath222 we obtain : @xmath223 inserting the explicit forms for the @xmath97-factors into eqn .
( [ limz ] ) and recalling that @xmath218 are independent of @xmath11 , we read off the relation between the two sets of coefficients : @xmath224 combining eqns .
( [ ab ] ) and ( [ lrw ] ) provides us with an _
identity _ between sr and hybrid wilson functions : @xmath225 here , @xmath127 and @xmath128 denote the wilson functions of the sr model , eqn .
( [ srwf ] ) , evaluated at @xmath226 . in the following , we use the abbreviated notation @xmath227 and @xmath228 .
( [ srh ] ) form the basis for the remainder of the paper : they hold the key for the discussion of the hybrid theory and for the desired matching between lr and sr models .
it is particularly gratifying that they are valid _ to all orders _ in perturbation theory .
an explicit calculation of the hybrid wilson functions , instead of the general considerations presented above , would establish eqns .
( [ srh ] ) only up to a given order . to discuss the rg flow for the hybrid theory , we compute the @xmath120-functions for the couplings @xmath229 : @xmath230 \bar{u } , \nonumber \\ \beta _ { \bar{w}}\left ( \bar{u},\bar{w},v\right ) & = & \left
. \mu \partial _ { \mu } \bar{w}\right| _ { bare}=\left [ \bar{\zeta}_{\rho } -\bar{\zeta}_{\sigma } + \alpha \frac{v}{1+v}\left ( 2-\bar{\zeta}_{\rho }
\right ) \right ] \bar{w } , \nonumber \\ \beta _ { v}\left ( \bar{u},\bar{w},v\right ) & = & \left .
\mu \partial _ { \mu } v\right| _ { bare}=-\biggl [ \left ( 1+v\right ) \bar{\zeta}_{\sigma } + \alpha \left ( 2-\bar{\zeta}_{\rho } \right ) \biggr ] v , \label{hbf}\end{aligned}\ ] ] and seek their fixed points @xmath231 .
these fall into two groups .
the _ first _ group is characterized by @xmath232 : in this case , eqns .
( [ hbf ] ) reduce to the fixed point equations ( [ srbf ] ) for the sr theory , so that we recover the equivalents of the familiar sr fixed points , namely ( i ) the fdt satisfying @xmath233 , ( ii ) the fdt violating @xmath234 , ( iii ) the fixed point @xmath235 on the separatrix between ( i ) and ( ii ) , and finally the gaussian fixed line ( iv ) @xmath236 .
in contrast to the sr case , however , their stability needs to be investigated in the _ three_-dimensional space spanned by @xmath237 , controlled by the @xmath238 matrix @xmath239 , @xmath240 . for @xmath232 , we find @xmath241 at all of these fixed points , so that only the upper left @xmath117 corner of @xmath242 ( which is just @xmath243 ) , and the bottom right element , @xmath244 , are relevant .
the eigenvalues of @xmath245 were already computed in section ( 3.1 ) , so that only fixed points ( i ) and ( ii ) remain as candidates for global stability if @xmath123 . for fixed point ( i ) ,
@xmath246 to all orders ( cf .
section 3.1 ) so that @xmath247 is positive for @xmath248 .
thus , @xmath249 demarcates the stability boundary of the fdt satisfying sr fixed point ( i ) .
considering fixed point ( ii ) , we have @xmath250 and @xmath251 , giving positive values for @xmath252 provided @xmath253 .
so , the fdt violating sr fixed point ( ii ) remains stable for a larger region of @xmath11 than its fdt - satisfying partner .
we remark that , in contrast to @xmath249 , @xmath254 is known only perturbatively . finally , the fixed line @xmath236 is stable provided both @xmath19 and @xmath11 are negative . returning to @xmath123 ,
it is clear that another fixed point must become stable beyond @xmath254 . by necessity
, this can only be a member of the _ second _ group , having @xmath255 .
for all of these , the @xmath256 $ ] bracket in the last line of eqns .
( [ hbf ] ) vanishes , so that the first two equations simplify to @xmath257 \bar{u } , \nonumber \\
{ \bar{w}}\left ( \bar{u},\bar{w},v^{\ast } \right ) & = & \biggl[2\alpha + \left ( 1-\alpha \right ) \bar{\zeta}_{\rho } \biggr]\bar{w}. \label{hbfs}\end{aligned}\ ] ] one should note that , with @xmath258 , @xmath259 is precisely the @xmath120-function of the lr theory , eqn .
( [ lrbf ] ) .
thus , we identify the second group as the hybrid partners of the lr fixed points .
the equation for @xmath260 has a trivial solution @xmath261 and a nontrivial one , with @xmath262 .
seeking the corresponding values for @xmath263 , we obtain a `` gaussian '' fixed point ( v ) @xmath264 and a nontrivial one ( vi ) with @xmath265 @xmath266 , @xmath267 and @xmath268 + 2\alpha /3+o\left ( \varepsilon ^{2}\right ) $ ] .
note that we have expanded @xmath269 in both @xmath19 and @xmath11 , keeping only terms to first order in either , since both are assumed to be of the same order .
@xmath270 is @xmath12 which should not be disturbing since @xmath271 is not a perturbative coupling . since @xmath262 here , we find @xmath272 to all orders . turning to the stability of these fixed points , it is straightforward to determine that the gaussian line is stable for @xmath273 , i.e. , above the upper critical dimension of the lr theory . for @xmath274 , we find a more complex situation : for @xmath275 , fixed point ( vi ) has two unstable directions .
one of these becomes stable above @xmath249 . for @xmath276 ,
this fixed point is globally stable .
it is natural , of course , to seek fixed points where neither @xmath277 nor @xmath278 vanish .
this attempt gives us a pair of equalities , valid to all orders : @xmath279 which do _ not _ result in a unique equation for such a fixed point .
instead , they select a specific value of @xmath11 , namely @xmath280 , where a fixed _ line _ ( vii ) exists , parameterized by @xmath281 : @xmath282 , \bar{w},\left ( 3\bar{w}-1\right ) \left ( 1-\bar{w}\right ) /\left ( 3\bar{w}^{2}+2\bar{w}+3\right ) \right ) $ ] .
this line mediates the stability loss of fixed point ( i )
. the crossover scenario between the sr and the true lr theory can now be summarized .
let us fix @xmath17 just below @xmath192 and increase @xmath11 starting from zero .
for sufficiently small @xmath283 , the rg flow is dominated by the sr behavior .
the sr fixed points ( i ) and ( ii ) are stable , within their respective domains of attraction .
the separatrix forms a surface which cuts the @xmath284 plane at @xmath285 and then bends over to larger values of @xmath281 as @xmath86 increases .
the unstable lr fixed point ( vi ) is found on the separatrix , in the unphysical region @xmath286 .
when @xmath11 reaches @xmath249 , the correlated noise begins to make its presence felt .
specifically , for @xmath287 , the fdt violating fixed point ( ii ) is the only globally stable fixed point .
the fdt restoring fixed point ( i ) , while still stable _ within _ the @xmath284 plane , has become unstable to small perturbations _ out _ of that plane .
thus , a flow line starting near ( i ) , with a small @xmath288 component , will first flow out into the half - space @xmath288 and then bend _ back _ towards @xmath284 , flowing into the fdt violating fixed point ( ii ) .
the _ sign _ of @xmath86 remains invariant under the flow .
the lr fixed point ( vi ) is still unphysical , but has moved closer to the @xmath284 plane .
finally , at @xmath289 @xmath254 , ( vi ) merges with ( ii ) and moves out into the positive @xmath86 region as @xmath11 increases beyond @xmath254 . the lr fixed point ( vi )
is now the only stable one , and the global rg flow is dominated by the lr theory .
a different view of the sr - lr crossover is presented in fig . 1 which shows the location of the stability boundaries as functions of @xmath11 and @xmath17 .
it is interesting to note the two different scenarios which control the stability loss of fixed points here .
fixed points ( ii ) and ( vi ) exchange their stability by merging , similar to the stability exchange between the gaussian and the wilson - fisher @xcite fixed points in @xmath13-theory when @xmath17 drops below @xmath290 .
in contrast , fixed point ( i ) loses its stability , at @xmath291 , by generating a _ fixed line_. this fixed line has two key properties : first , it connects fixed points ( i ) , ( iii ) and ( vi ) ; second , it lies on the surface forming the _ separatrix _ between fixed points ( i ) and ( ii ) .
this surface bends back towards the @xmath284 plane , as @xmath23 increases , to the extent that it _ reaches _ fixed point ( i ) at @xmath292 .
thus , fixed point ( i ) loses one of its three stable directions when being absorbed by the separatrix ; moreover , this direction is now spanned by the fixed line : this allows the flow to change sign when @xmath23 crosses @xmath249 . the crossover which we observe in the flow diagrams is also reflected by the exponents . as an example , we consider the scaling form of the lr structure factor , eqn .
( [ lrs ] ) .
we recall that its scaling behavior is determined by the exponent @xmath293 . the hybrid fixed point ( vi ) , on the other hand
, generates an exponent @xmath294 .
these two exponents clearly match , since @xmath295 .
as @xmath11 decreases , we reach the stability boundary @xmath296 , where ( vi ) and ( ii ) exchange stability . here , the exponent associated with ( ii ) is @xmath297 , to be compared with the corresponding value near ( vi ) , @xmath298 . in this way , continuity is ensured .
however , a discontinuous change of exponents may occur as @xmath11 decreases below @xmath249 : above @xmath249 , all positive @xmath237 fall into the domain of attraction of fixed point ( ii ) , with @xmath299 ; in contrast , below @xmath249 , some of these will be attracted towards fixed point ( i ) where @xmath300 . for these theories ,
the strong anisotropy exponent @xmath301 will change _ discontinuously _ upon crossing the stability boundary between fixed points ( i ) and ( ii ) .
note , however , that @xmath300 coincides with @xmath293 at the line @xmath302 to all orders in @xmath19 . nevertheless , even though the exponents may undergo discontinuities , both the hybrid and the sr structure factors scale according to eqn .
( [ srs ] ) .
thus , the scaling _
forms _ remain unchanged .
using field theoretic methods , we have analyzed the rg flow for a model of biased diffusion subject to a noise term , parameterized by its momentum dependence , @xmath303 , with spatially long - ranged correlations .
one limit , @xmath4 , corresponds to a `` short - range '' model with purely local , conserved noise , and the other , @xmath5 , models biased diffusion with a non - conserved noise .
the crossover from @xmath304 to @xmath5 presents no difficulties ; however , the opposite limit , @xmath181 , is quite subtle . here
, the full crossover is observed only if we interpose a hybrid model with @xmath305 , between the sr ( @xmath4 ) and the lr ( @xmath11 finite ) theories .
this hybrid contains the key elements of both , sr and lr , langevin equations .
it possesses a number of fixed points , including the equivalents of the sr and the lr models , so that the crossover can be understood in terms of a stability exchange between different fixed points .
clearly , considering @xmath11 on the scale of @xmath19 enables us to resolve this `` fine structure '' . just below two dimensions ,
the scenario is following : for @xmath11 below a lower stability limit @xmath249 , the theory is controlled by two stable sr fixed points , one fdt restoring and the other fdt violating , each with its own basin of attraction .
stated differently , we are in a `` weak noise '' regime , for @xmath306 , where the long - ranged noise does not significantly modify the universal behavior of the system . as @xmath11 increases beyond @xmath249 but remains below an upper stability limit @xmath307 , the sr fdt restoring fixed point becomes unstable , leaving the sr fdt violating fixed point in control of the flow .
this stability exchange is mediated by a fixed point line . finally , above @xmath254
, the sr fdt violating fixed point also destabilizes and the nontrivial lr fixed point becomes globally stable .
we note , in conclusion , that a similar mechanism , namely stability exchange through a fixed point line , has previously been observed in the sine - gordon model : there , two fixed points are stable below @xmath308 , corresponding to the high- and low - temperature phases , respectively .
as @xmath17 increases beyond @xmath192 , the high - temperature fixed point loses its stability , via a similar fixed point line @xcite .
unfortunately , most of the nontrivial crossover phenomena discussed here are confined to dimensions @xmath309 @xmath192 . above @xmath184 ,
the long - range noise dominates , either via its nontrivial or its gaussian fixed point . in one dimension ,
on the other hand , there is no transverse subspace so that the sr fdt violating fixed point can not be accessed .
consequently , the scenario described above must change significantly .
it is conceivable that only the lower stability limit might survive here or that the two stability limits merge , leaving us with a stability exchange between the fdt restoring sr and the lr fixed point . since , at @xmath291 , @xmath310 to all orders , this may be a reasonable conjecture .
moreover , in @xmath21 , we have @xmath311 and @xmath312 .
these values agree with the corresponding results @xcite for the one - dimensional kpz equation with correlated noise where only one stability limit is observed .
nevertheless , our analysis plays the role of a pilot study for a number of other interesting problems .
clearly , one might consider an interacting theory subject to an external bias @xcite and a long - range noise term @xcite . here ,
@xmath313 , so that physical dimensions are more accessible , and comparisons with monte carlo simulations can be made .
other questions of interest concern noise terms with different spatial correlations , or nontrivial correlations in time . for equilibrium systems ,
the existence of an underlying hamiltonian ensures that these correlations have no effect on static properties . for non - equilibrium
steady states , however , the static behavior is generically inseparable from the dynamics .
studies of anomalous noise correlations in non - equilibrium systems may help to unravel the nature of this coupling .
we wish to thank r. bausch and r.k.p .
zia for valuable discussions .
bs also gratefully acknowledges the kind hospitality of the institut fr theoretische physik iii of the heinrich - heine - university of dsseldorf where some of this work was performed .
this research is partially supported by sfb 237 ( `` unordnung und groe fluktuationen '' ) of the deutsche forschungsgemeinschaft and the us national science foundation through the division of materials research .
gwa and h. spohn , phys .
lett . * 68 * , 725 ( 1992 ) and phys .
a * 46 * , 844 ( 1992 ) ; b. derrida , m.r .
evans , and d. mukamel , j. phys .
a : math . gen .
* 26 * , 4911 ( 1993 ) ; g.m .
schtz , j. stat .
phys . * 86 * , 1265 ( 1997 ) .
janssen , z. phys .
b : cond . mat .
* 23 * , 377 ( 1976 ) ; c. de dominicis , j. phys .
( france ) colloq . * 37 * , c247 ( 1976 ) ; h.k .
janssen , in _ from phase transitions to chaos _ , g. gyrgyi , i. kondor , l. sasvri , and t. tl , eds .
( world scientific , singapore , 1992 ) . | the diffusion of hard - core particles subject to a global bias is described by a nonlinear , anisotropic generalization of the diffusion equation with conserved , local noise .
using renormalization group techniques , we analyze the effect of an additional noise term , with spatially long - ranged correlations , on the long - time , long - wavelength behavior of this model . above an upper critical dimension @xmath0
, the long - ranged noise is always relevant .
in contrast , for @xmath1 , we find a `` weak noise '' regime dominated by short - range noise . as the range of the noise correlations increases , an intricate sequence of stability exchanges between different fixed points of the renormalization group occurs .
both smooth and discontinuous crossovers between the associated universality classes are observed , reflected in the scaling exponents .
we discuss the necessary techniques in some detail since they are applicable to a much wider range of problems .
pacs numbers : 64.60.ht , 64.60.ak , 05.40.+j + keywords : non - equilibrium steady states , driven diffusive systems , correlated noise . |
SACRAMENTO, Calif. (AP) — A man who originally pleaded not guilty to starting a massive fire two years ago has now admitted he ignited the blaze that burned 80 structures in Northern California.
Thirty-nine-year-old Wayne Allen Huntsman pleaded guilty Friday to three counts of felony arson in the September 2014 King Fire.
El Dorado County Superior Court Judge Daniel Proud sentenced Huntsman to 20 years in prison and ordered him to pay $60 million in restitution.
The King Fire burned 12 homes, 68 other structures and more than 150 square miles of land in the north-central Sierra Nevada mountains. It took 300 firefighters and personnel about a month to control.
Huntsman made a video of himself during the fire that District Attorney Vern Pierson says was an attempt to portray himself as a hero. ||||| The interactive transcript could not be loaded.
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This feature is not available right now. Please try again later. ||||| Man pleads guilty to setting King Fire after selfie video emerges
A 37-year-old man was sentenced to 20 years in prison after he pleaded guilty to starting the 2014 King Fire, which burned a dozen homes and nearly 100,000 acres east of Placerville in the central Sierra.
The case against Wayne Allen Huntsman of Pollock Pines (El Dorado County) was nailed down in part because of a selfie video that Huntsman made at the fire’s origin, the El Dorado County district attorney’s office said Friday.
In the video, recorded Sept. 13, 2014, Huntsman is standing in a forested area between two separately lit blazes, which prosecutors construed as a sign that the fire was intentionally set. Although Huntsman says on his video, “I’m stuck in the middle,” he smiles and does not appear to be fearing for his safety.
A retired firefighter picked up Huntsman after the blaze began. He saw Huntsman’s selfie and recorded it on his own phone, then turned over his video to law enforcement officials, who arrested Huntsman four days later.
Huntsman was also caught on surveillance video, after starting the fire, stealing liquor from a local grocery store, prosecutors said.
The fast-moving inferno burned for nearly a month across 97,717 acres of mostly mountainous terrain along Highway 50 in the El Dorado National Forest. Thousands were forced to evacuate. Damages were estimated in the tens of millions.
Huntsman is originally from the Santa Cruz area, but he moved to Pollock Pines in June 2013 for work, family members told The Chronicle. He was doing odd jobs, mostly home remodeling and landscaping, and living with his girlfriend.
Huntsman has a criminal record that includes convictions for assault with a deadly weapon and grand theft in Santa Cruz County in 1997, public records show. None of his earlier crimes related to arson.
Superior Court Judge Daniel Proud sentenced Huntsman to the maximum allowed for three counts of arson with multiple enhancements for causing injury to firefighters and destroying structures, according to the district attorney’s office.
Huntsman was also ordered to pay $60 million in restitution.
Kurtis Alexander is a San Francisco Chronicle staff writer. Email: [email protected] Twitter: @kurtisalexander | – A man who took a video of himself after starting a fire that would go on to burn more than 150 square miles of land was sentenced to 20 years in prison and a $60 million fine, the AP reports. According to Reuters, Wayne Huntsman pleaded guilty to three counts of arson Friday for starting the 2014 King Fire in Northern California that took hundreds of firefighters a month to get under control. His sentence was increased because a number of firefighters were injured and 12 homes and dozens of other structures were destroyed. Thousands of residents were displaced by the fire. Huntsman originally pleaded not guilty to the charges. In September 2014, a retired firefighter picked Huntsman up escaping the area of the blaze, the San Francisco Chronicle reports. Huntsman showed the man a video of himself standing between two fires. "Listen, I got fire all around me," Huntsman says in the video. "I'm stuck in the middle, babe." The man made a recording of the video and turned it over to the authorities, who arrested Huntsman within days. The DA says Huntsman was trying to look like a hero in the video, but it appeared the fires were purposefully set because there were two of them and Huntsman seemed to be enjoying himself. Meanwhile, Huntsman's sister is accused of killing two young children, whose bodies were found in a storage locker in Redding, California, according to SFist. |
the prevalence of nafld in the general population is around 2030% , whereas among patients with type 2 diabetes it is up to 80% .
nafld is strongly correlated with metabolic syndrome , including visceral obesity , atherogenic dyslipidemia , insulin resistance , impaired glucose metabolism , or type 2 diabetes [ 15 ] .
the pathogenesis of nafld is not entirely understood , but there is a great deal of evidence suggesting that nafld is actually a hepatic manifestation of metabolic syndrome [ 14 ] .
nafld is characterized by steatosis of hepatocytes , which is usually macrovesicular , and can be diagnosed after exclusion of other risk factors for chronic liver diseases such as alcohol abuse , drugs , or chronic viral hepatitis .
there is some data indicating that cardiovascular complications are more common among patients with diabetes and nafld than in patients without liver disease .
nafld is associated with increased risk of all - cause mortality and predicts future cvd events independently of other risk factors [ 69 ] .
targher suggests that nafld might be not only a marker , but also an early mediator of cardiovascular diseases .
the aim of our study was to determine the factors associated with the presence of nafld in patients with type 2 diabetes .
we also tried to find an association between nafld and diabetic macroangiopathy in patients with type 2 diabetes .
we examined consecutive patients with type 2 diabetes from a diabetic clinic , 72 of which had nonalcoholic fatty liver disease diagnosed by abdominal ultrasonography .
ultrasonographic measurements were performed by experienced radiologists who were blinded to the clinical presentations and laboratory finding of the subjects .
hepatic steatosis was defined as a diffuse increase in fine echoes in the liver parenchyma , as compared with the parenchyma of the kidney or spleen .
individuals that defined themselves as alcohol drinkers or consumed more than 30 g of ethanol daily ( or its equivalent ) were excluded from the study .
patients with hepatitis b virus antigen or hepatitis c virus antibody , and patients with chronic liver disease were excluded .
laboratory tests were done in the fasting state including serum enzymes activity , serum lipids , glucose and creatinine concentrations , and glycated hemoglobin a1c .
blood lipids were determined by enzymatic methods , using roche reagents , and hba1c was assessed by high pressure liquid chromatography .
body mass index ( bmi ) was calculated by dividing the weight in kilograms by the height in meters squared .
blood pressure was measured twice , with the subjects in a sitting position , using an automated device ; the mean of 2 measurements was calculated .
coronary heart disease ( chd ) was defined as the presence of stable angina , past ami , past revascularization procedure , or ptca .
means and standard deviations were calculated for continuous data . for group comparisons of continuous variables ,
the chi - square test of independence i was used for comparison of categorical variables .
the logistic regression model was used to estimate the importance of examined variables association with fatty liver disease .
we examined 101 patients with type 2 diabetes ( 64 men and 37 women ) .
patients with nafld were older than patients without nafld ( mean age 53.110.4 yrs vs. 44.910.9 yrs , respectively ( p<0.001 )
. however , mean duration of diabetes was shorter : 10.06.3 years in patients with and 157.8 years in those without nafld ( p<0.001 ) .
insulin treatment had been received by 72% of nafld patients , and insulin dosage was significantly higher in patients with nafld than without nafld ( 69.930 units of insulin/24 h vs. 51.731.4 units/24 h , p=0.016 ) ; the mean insulin dosage per kilogram of body weight was 0.710.3 vs. 0.650.3 ( p = ns . ) patients with nafld were characterized by significantly higher prevalence of coronary angioplasty ( 20.8% vs. 0% , p=0.008 ) , but the incidences of coronary heart disease and by - pass surgery were not different between groups .
overweight and obesity were observed in a higher percentage of nafld patients ( p<0.001 ) .
nafld patients were characterized , as expected , by significantly higher values of alanine transaminase ( p=0.033 ) and lower concentrations of serum of hdl - cholesterol ( p<0.001 ) and creatinine ( p=0.034 ) .
after standardization by age and glycated hemoglobin , only hdl - cholesterol and triglyceride concentrations were significantly different between groups .
multiple logistic regression analysis with nafld as a dependent variable was examined in 2 models ( table 3a and 3b ) both models were significant ( p<0.001 ) . in the first model , which included waist circumference above normal
( women > 80 cm , men > 94 cm ) , hba1c , alat , and creatinine concentration , only waist circumference and alanine transaminase were associated positively , while creatinine was negatively associated with the presence of fatty liver . in the second model ( which included serum lipids ) , waist circumference above normal ( p=0.007 ) and total cholesterol ( p=0.0079 )
were positive predictors of nafld , and hdl - c ( p=0.0032 ) was a negative predictor of nafld .
another measure of obesity , body mass index was also a significant predictor of nafld , while waist to hip ratio did not have significant influence .
we did not find an association between presence of nafld and glycemic control as measured by hba1c .
interestingly , glycemic control was associated with liver enzymes in patients with type 2 diabetes and nafld . in patients with nafld , there were significant positive correlations between glycated hemoglobin and waist circumference ( r=0.3188 , p=0.010 ) , ldl - c ( r=0.2479 , p=0.048 ) , ggtp ( r=0.3275 , p=0.032 ) , and fa ( r=0.5882 , p<0.01 ) and negative correlations with hdl - c ( r=0.2602 , p=0.038 ) were observed . in patients without nafld ,
the only significant correlation was observed between hba1c and triglyceride level ( r=0.5122 , p=0.009 ) .
this study characterized the clinical and biochemical features of patients with type 2 diabetes and nafld .
we also confirmed the important role of central obesity in the development of nafld , observed by others , in patients with diabetes . in our study , presence of ultrasonographically documented nafld was associated with 2 features of metabolic syndrome : central obesity and low hdl cholesterol concentrations .
visceral obesity seems to be the key associate of nafld in patients with as well as without diabetes [ 1214 ] .
low serum concentration of hdl - c and higher concentrations of triglycerides , the key features of insulin resistance dyslipidemia , were significantly different between patients with and without nafld , after standardization by age and hba1c .
however , only low concentration of hdl - c and high levels of total cholesterol remained highly significant predictors of nafld in multiple logistic analysis . in the multi - ethnic study of atherosclerosis , a prospective population - based study ,
nafld was associated with lower fasting hdl - c , as in our group of patients . in the above study ,
our findings suggest that serum triglyceride , a marker of insulin resistance , is less associated with nafld than hdl - c . according to data in the literature
, it is well established that hdl lipoproteins are small , dense , and dysfunctional in patients with type 2 diabetes , so it seems that our results warrant further investigation of hdl function .
statins are currently the first - line drug and ldl - c is the goal of treatment of diabetic dyslipidemia
. however , it seems important , from the present study and literature data , to obtain desirable hdl cholesterol , not only because of cardiovascular disease prevention , but also to prevent of fatty liver disease . at the present time we do not have efficacious treatment of low hdl cholesterol , apart from life - style modification , fibrates , and statins .
effects of statins and fibrates on hdl - c in patients with type 2 diabetes are modest , while niacin does not seem to bring improvement in clinical trials on cardiovascular events , despite increase of hdl - c concentrations . in patients with fatty liver ,
it is surprising , as literature data indicates , that the presence of nafld enhances insulin resistance and cytokine release from fat - loaded liver cells and thereby enhances development of diabetes type 2 .
we also noted that nafld patients with type 2 diabetes are older than those without fatty liver .
several studies showed an association between nafld and higher prevalence of coronary heart disease and other diabetes complications [ 1821 ] . in our study
, we did not confirm these observations ; however , in our group of patients , a higher number of those with nafld required ptca than patients without fatty liver .
this phenomenon might be related to higher procoagulant activity or worse endothelial function associated with low hdl cholesterol concentrations , as observed in our patients with nafld .
the group of patients with nafld had lower levels of creatinine as compared to the group without nafld .
serum creatinine concentration is dependent on age , sex , muscle mass , volume status , and renal hemodynamics .
thus , lower creatinine levels in nafld patients could be the result of lower body muscle mass among people with nafld , because creatinine level is strongly correlated with total body muscle mass . in our study ,
glycemic control was negatively associated with fa and ggtp activity , the markers of nafld in patients with metabolic syndrome .
alat is elevated in up to 80% of patients with nafld and is mainly a marker of hepatocellular damage .
recently , iwasaki et al reported that nafld is associated with adverse therapeutic effect of sitagliptin in patients with type 2 diabetes .
this could be the result of high serum ddp-4 activity observed in patients with nafld .
taken together , the presence of nafld could be an indicator suggesting requirements for higher doses of dpp-4 inhibitor .
the diagnosis of nafld was based on ultrasonographic examination , performed by 2 experienced technicians , which is a generally accepted method of fatty liver diagnosis ; however , we did not use reference and invasive biopsy diagnosis .
the diagnoses of cardiovascular events were based only on medical history , so some patients with coronary heart disease could have been under - detected .
the results of this study indicate that central obesity and dyslipidemia , with low hdl cholesterol , are important associates of nafld in patients with type 2 diabetes . in our patients with type 2 diabetes , glycemic control was associated with abnormal liver function tests and with unfavorable lipid profile , as well as with central obesity . | backgroundthere is evidence that nonalcoholic fatty liver disease ( nafld ) is associated with increased cardiovascular risk . in this study
we examined factors associated with the presence of nafld and the prevalence of macroangiopathy in patients with type 2 diabetes.material/methodssubjects were 101 consecutive patients with type 2 diabetes : 72 with nafld and 29 free of nafld .
nafld was diagnosed by ultrasonography .
serum lipids were measured enzymatically and glycated hemoglobin hba1c was measured by hplc.resultsthe mean age of patients was 53.110.4 in the nafld group and 44.910.9 years in patients without nafld ( p<0.001 ) .
the mean duration of diabetes was 106.3 years in patients with nafld and 15.17.8 years in those without nafld ( p<0.001 ) .
mean values of glycated hemoglobin a1c were similar in both groups .
patients with nafld were characterized by a significantly higher prevalence of coronary angioplasty ( 20.8% vs. 0% , p=0.008 ) .
overweight and obesity were observed in a higher percentage of patients with nafld ( p<0.001 ) .
patients with nafld were characterized by significantly higher values of alanine transaminase ( p=0.033 ) , and lower serum concentrations of hdl - cholesterol ( p<0.001 ) and creatinine ( p=0.034 ) . logistic regression analysis ( p<0.001 ) revealed that nafld was positively associated with waist circumference above normal ( women > 80 cm , men > 94 cm ) ( p=0.0083 ) and alanine transaminase activity ( p=0.0164 ) , and negatively with creatinine concentration ( p=0.0226 ) . in a second logistic regression model ( p<0.001 ) , waist circumference
( p<0.007 ) and total cholesterol ( p<0.008 ) were positive predictors , while hdl - c ( p<0.003 ) was a negative predictor of nafld.conclusionsthe results of the study suggest that nafld is associated with visceral obesity and low hdl - cholesterol in patients with type 2 diabetes . |
lethal midline granuloma is a midfacial necrotizing lesion that is characterized by destructive , mucosal lesions of the upper aero digestive tract .
the underlying mucosa is thickened and the patient usually develops extensive midfacial destructive lesions , perforated nasal septum and erosion of the nasal bone .
the disease is localized to the upper aerodigestive tract at presentation but dissemination to distant sites may occur .
constitutional symptoms may develop . also referred to as polymorphic reticulosis , midline malignant reticulosis , stewart s granuloma most of the lethal midline granulomas are nk / t cell lymphomas . here
, we present a case of nk cell lymphoma in a 35 year old male who came with a short clinical history .
a 35 year old male presented with swelling in the right side of neck since two months .
this was followed by pain and swelling on the dorsum of nose since one and a half months .
patient also gave a two week history of stuffiness in the right nostril and bilateral nasal mucopurulent discharge .
, there was a 5 4 cm swelling on the right side of dorsum of nose and nasolabial fold .
there was no history of epistaxis , anosmia , post nasal drip , oral bleed or cough .
clinical photo showing swelling and erythema on the dorsum of the nose all routine hematological and biochemical investigations were normal .
hiv , hbsag and vdrl were negative . a contrast enhanced computed tomogram ( cect ) of the paransal sinuses showed right sided superficial medial canthus related right sided nasolabial disease with metastatic right sided cervical and submandibular lymphadenopathy .
a biopsy was taken from the mass and sent to national institute of pathology for histopathological examination . a diffuse lymphomatous infiltrate having an angiocentric and angiodestructive pattern
plasma cells , histiocytes and eosinophils were present admixed with atypical lymphocytes [ figure 2c ] .
immunohistochemistry was performed and the lymphomatous infiltrate was found to be positive for lca [ figure 3a ] , cd56 [ figure 3b ] and cd3 [ figure 3c ] .
however fungal stains , periodic acid schiff ( pas ) were done to exclude fungal disease . based on these findings a diagnosis of extranodal nk cell lymphoma was made .
the patient was referred to the oncology department for further management and he received four cycles of multidrug chemotherapy ( chop regimen ) .
follow - up the mass had slightly reduced in size , there was relief from episodes of epistaxis and nasal discharge had stopped .
( a ) photomicrograph showing diffuse lymphomatous infiltrate destroying the hair follicles ( h and e , 40 ) ; ( b ) photomicrograph showing extensive areas of necrosis ( h and e , 100 ) ; ( c ) photomicrograph showing atypical lymphocytes admixed with histiocytes , plasma cells and eosinophils ( h and e , 400 ) ( a ) ihc showing atypical lymphocytes positive for lca ( h and e , 100 ) , ( b ) ihc showing atypical lymphocytes positive for cd56 ( h and e , 100 ) , ( c ) ihc showing atypical lymphocytes positive for cd3 ( h and e , 100 )
malignant lymphomas of the sinonasal region and nasopharynx are majorly of non - hodgkins lymphoma type and fall either into nk / t cell type , b cell type or peripheral t cell type .
the most common of the so called nasal type in which the nasal cavity is the prototype site of involvement are the extranodal nk / t cell lymphomas . in the past
this entity has been referred to as lethal midline granuloma , polymorphic reticulosis , malignant midline reticulosis .
macroscopically the lesions usually look like necrotic granulomas and are characterized by ulceration and destruction of the nose and paranasal sinuses with erosion of soft tissues , bone and cartilage of the region .
the patients show an aggressive and lethal course with rapid destruction of the nose and face ( midline ) , therefore the term lethal midline granuloma .
this disease occurs around the fourth decade and the male to female ratio is 8:1 to 2:1 .
morphologically it is characterized by extensive ulceration of mucosal sites with a lymphomatous infiltrate that is diffuse , but has an angiocentric and angiodestructive growth pattern .
nk cells are active against tumor cells and cells infected with bacteria or viruses without prior sensitization .
these develop from precursor cells that can differentiate into nk / t cells and this explains why some of the nk cells can also express t cell markers .
the most common immunophenotype of the is cd56 + , cd2 + and surface cd20-.[357 ] seen mostly in adults in the asian and mexican region , skin involvement is seen in 10 - 20% of patients .
our patient was a 35 year old male with short history of right sided nasal obstruction and discharge with same sided tender erythematous lesion with lesional biopsy showing atypical lymphoid cells that were positive for cd56 on ihc .
nasal nk / t cell lymphoma is an aggressive disease with a rapid downhill course .
untreated , this disease has a very high mortality reaching almost 100% due to septicemia , perforation into blood vessels or penetration into brain leading to abscess .
wang et al . , reported combined chemotherapy followed by involved field external radiation beam to be beneficial in patients and prolonged progression free survival rates .
the confusing clinical picture of this disease calls for a high degree of suspicion for correct diagnosis and early intervention to prolong the patient survival . | lethal midline granuloma is a relatively rare disease characterized by destruction and mutilation of the nose and other structures of respiratory passages .
the nonspecificity of symptoms obscures the correct diagnosis and is responsible for the delay in treatment which can be detrimental as this grave disease calls for urgent intervention .
we present a case report of this disease in a 35 year old male who gave a short two month history of the clinical symptoms . |
squamous cell cancer of the head and neck ( scchn ) is a major contributor to morbidity and mortality and accounts for approximately 5% of all new cancer diagnoses . worldwide , more
than 600,000 new cases are diagnosed every year and 350,000 cancer deaths can be attributed to this disease.1 the majority of patients are diagnosed in the locally advanced and metastatic stages and survival has been poor despite the fact that scchn is very sensitive to treatment with a high rate of remissions . as chemotherapy combinations have become increasingly intense in recent years ,
it has become evident that a limit has been reached where gains in activity and response rate are offset by greater toxicities.2 targeted therapies with their different side effect profile offer the possibility to further expand and intensify combination therapy and numerous trials have explored this strategy in many fields of solid tumor oncology including head and neck cancer .
the advances in the basic sciences and an ever increasing number of potential targets have created a new wealth of therapeutic possibilities that are now explored in various stages of pre - clinical and clinical development . in the last few years in particular ,
however , an increasingly comprehensive picture is just beginning to emerge and clinical testing remains critical .
head and neck cancer treatment is also transforming as a result of targeted therapies . among the first potential targets that were recognized in scchn was the epidermal growth factor receptor ( egfr ) .
it is overexpressed in many types of epithelial neoplasms including scchn where robust overexpression is found in > 90% of cases .
the egfr / erbb1 receptor is a member of the tyrosine kinase superfamily along with the other three members of the erbb tyrosine kinase family which include erbb2 ( her2/neu ) , erbb3 ( her3 ) , and erbb4 ( her4).3 the egfr includes a ligand binding extracellular domain at the n - termial end , a transmembrane section that anchors the molecule in the cell membrane and an intracellular domain that transmits signals to a multitude of downstream signaling pathways . upon binding of a ligand such as egf or transforming growth factor- ( tgf- ) , dimerization of
the egfr occurs and phosphorylation of intracellular tyrosine residues trigger activation of the egfr complex and the downstream signaling cascade.4 among the pathways involved in egfr signal transmission are the map kinase and the pi3 kinase pathways with their downstream effectors , respectively , that control a vast array of intracellular processes including cell cycling , cell adhesion and migration among others.58 strategies to block activity of the egfr have been explored in the past years and have become an established part of modern scchn treatment .
inhibition of egfr activity can be achieved through the following main methods : 1 ) through antibody binding to the receptor , which interferes with ligand binding and induces internalization and subsequent breakdown of the antibody - egfr complex in addition to immunologic events that may result in destabilization of targeted cells , 2 ) with small molecules that act as competitive inhibitors to the intracellular adenosine triphosphate ( atp)-binding site , and 3 ) through specific downregulation of the egfr .
anti - egfr chimeric monoclonal antibodies include cetuximab ( c225 , erbitux ) and fully humanized antibodies such as panitumumab , matuzumab , nimotuzumab , and zalutumumab .
they are specific to the extracellular portion of the egfr and exert their anti - egfr activity by inhibiting ligand binding , thus interfering with egfr activation .
they also induce internalization of the egfr resulting in a lower number of egfr at the cell surface .
furthermore , antibody binding may trigger an immunologic response resulting in the de - stabilization and ultimately apoptosis of the cancer cell . among this class of drugs ,
cetuximab ( erbitux ) has the longest track record and has been studied extensively in head and neck cancer . in patients with
locally advanced , potentially curable scchn , data from a randomized trial shows that the addition of cetuximab to radiation in the definitive treatment of locally advanced scchn results in improved local control , overall survival and time to progression compared with radiation alone.9 in a landmark study in 424 patients with stage iii and iv squamous cell cancer of the oropharynx , hypopharynx , or larynx , the median duration of locoregional control was 24.4 months among patients treated with cetuximab plus radiotherapy and 14.9 months among those given radiotherapy ( hazard ratio for locoregional progression or death , 0.68 ; p = 0.005 ) . with a median follow - up of 54 months ,
the median duration of overall survival was 49 months among patients treated with combined therapy and 29.3 months among those treated with radiotherapy alone ( hazard ratio for death , 0.74 ; p = 0.03 ) and progression - free survival was increased significantly as well .
interestingly , patients with oropharyngeal primary tumors enjoyed the greatest benefit compared to other locations highlighting biological differences within scchn , which affect response to treatment and outcomes . when cetuximab is used as the single agent in metastatic disease scchn patients , the response rate is modest around 15% .
however , a large , randomized trial tested cddp/5fu with or without the addition of cetuximab in 442 patients with overall survival as the primary endpoint .
median survival was 7.4 months in the chemotherapy alone arm compared to 10.1 months for chemotherapy plus cetuximab arm ( p = 0.036 ) which was one of the longest median survival times in this patient group ever recorded.10 side effects typically include the acneiforme rash ( 80% overall , 3% severe ) and interestingly correlates with a tumor response . in contrast , egfr expression as measured by immunohistochemistry in this study was not a reliable predictor of tumor response.11 allergic reactions are found in approximately 3% of patients who receive cetuximab and recent evidence suggests that reactions at least in some regions of the united states are triggered by carbohydrate residues added during the manufacturing process.12 other studies are evaluating cetuximab in combination with paclitaxel or docetaxel and promising response rates including a significant number of complete responses have been reported as abstracts.13 a particularly interesting drug combination is based on the observation that up - regulation of vascular endothelial growth factor ( vegf ) has been associated with cetuximab resistance , raising the possibility that combined targeting of vegf and egfr may enhance antitumor activity .
the results of a phase ii trial using cetuximab in combination with the humanized monoclonal vegf antibody bevacizumab in 28 patients with incurable head and neck cancer showed a partial response in 20%.14 perhaps more importantly this limited analysis also showed that the combination was well tolerated and appeared safe with no cases of grade 4 bleeding , the most concerning side effect given the risk of severe and sometimes fatal bleeding in squamous cell cancer of the lung in patients treated with bevacizumab .
studies using a similar , but fully humanized monoclonal anti - egfr antibodies such as panitumumab are also under way but no data from phase ii trials in patients with metastatic disease has yet been published .
other ongoing trials with cetuximab include a combination with a humanized monoclonal insulin - like growth factor receptor ( igfr ) antibody imc a12 .
preclinical studies suggest synergy between egf and igfr inhibition and a high rate of cell death was observed .
this trial is currently accruing patients to explore activity in incurable recurrent or metastatic disease patients and no results are available to date .
other antibody based strategies using toxin - bound antibodies directed against the egfr are currently being considered for use in head and neck cancer patients but no results are available to date .
a number of egfr - specific agents from the class of the small molecule tyrosine kinase inhibitors have emerged and are used in a variety of tumors , including scchn .
they are competitive antagonists of the atp - binding site , inhibiting phosphorylation and subsequently activation of the egfr receptor .
when used as single agent , the response rate appears comparable to that seen with anti - egfr antibodies .
studies led by investigators at the university of chicago evaluated gefitinib ( iressa ) in patients with recurrent scchn .
fifty - two patients were treated with 500 mg gefitinib per day and approximately half of the patients received gef itinib as second - line therapy . an objective response was found in 10.6% and perhaps more interestingly
there appears to be a dose dependence as the response rate to gefitinib at a lower dose ( 250 mg per day ) induces responses is only 1.4%.15 a similar agent , erlotinib ( tarceva ) , been tested in patients with recurrent disease and the response rate was 4% with a progression - free survival and overall survival similar to that seen with gefitinib.16 there is some evidence from these trials that response to erlotinib may be more likely in patients with a high egfr copy number indicative of egfr amplification.17 the side effect profile of the small molecule tyrosine kinase inhibitors are remarkably similar to the egfr antibodies and involve acneiform skin rash , diarrhea , and electrolyte disturbances including hypocalcemia and hypomagnesemia , which are thought to be directly linked to the blocking of the egfr - dependent renal reabsorption .
erlotinib combined with cisplatin and docetaxel demonstrated a response rate of 67% with 4/43 patients achieving a complete response .
median overall survival was 11 months ( 8.61 , 22.5 , 95% confidence interval ) and progression - free survival was 6.01 months ( 4.37 , 8.25 ) .
however , six patients had grade 3/4 febrile neutropenia , four patients had grade 3/4 dehydration , three patients had grade 3 diarrhea , and two patients had grade 3/4 gastrointestinal ( gi ) bleeding.18 similar to the combination of cetuximab with bevacizumab mentioned above , erlotinib has also been combined with bevacizumab in a phase i / ii trial in a total of 48 patients with metastatic scchn and improved efficacy compared with erlotinib alone was found .
median overall survival and progression - free survival were 7.1 months ( 95% ci : 5.79.0 ) and 4.1 months ( 95% ci : 2.84.4 ) , respectively .
the most common side effects of any grade were rash and diarrhea ( 41 and 16 of 48 patients , respectively ) and serious bleeding of grade 3 or higher occurred in three cases.19 other small molecule tyrosine kinase inhibitors that inhibit a broader range of tyrosine kinases such as vandetanib ( az6474 , zactima ) are also tested in scchn .
vandetanib was primarily developed as an inhibitor of the vegf receptor but also has significant egfr - inhibiting properties as well .
it is currently evaluated in combination with docetaxel and no results in scchn have been published .
downregulation of the egfr by direct injection of antisense dna is also pursued at specialized centers .
data from a phase i trial suggests that this approach is well tolerated and tumor responses were seen.20 however , given the scarcity of data and the invasiveness of the therapy , this approach needs further validation before a broader application could be considered .
drug combinations such as inhibitors of the toll - like receptor antagonist along with egfr inhibitors have been tested in cell culture studies and it appears that there may be synergy when both pathways are blocked.21 however , no clinical studies are currently exploring this strategy in head and neck cancer patients .
while perhaps the greatest gains have been made with combining egfr inhibition with radiotherapy in the locally advanced , curable stages , anti - egfr therapy has also become an established part of palliative treatment of scchn patients .
small molecule tyrosine kinase inhibitors also hold promise of advancing current treatments given their considerable biological activity and their convenient administration . despite this progress ,
the identification of tumor and patient characteristics that are linked to treatment response are still at early stages in scchn and future success will depend on a broad effort of clinicians , translational and basic scientists .
a personalized approach to treatment with egfr inhibitors in scchn and cancer treatment in general will be critical to achieve cost effectiveness and maximize clinical impact on patient s lives . | squamous cell cancer of the head and neck ( scchn ) is a major contributor to morbidity and mortality worldwide . in recent years ,
inhibition of the epidermal growth factor receptor has become an established treatment strategy in scchn both in the up - front treatment and in the recurrent and metastatic setting .
this review summarizes the most important developments of the recent past and provides an overview of newer developments . |
a persistent problem in understanding the absorbing material in ngc 4151 has been reconciling the vastly different gas columns inferred for the x - ray absorption and for the uv absorption .
the x - ray absorbing column varies between @xmath1 and @xmath2 .
bromage et al .
( 1985 ) estimated a total column for the uv - absorbing material of no more than @xmath3 .
the neutral hydrogen column is variable ( kriss et al .
the bulk of the absorption is in low column density gas with @xmath4 and doppler parameter @xmath5 .
any low - b component has a neutral column no greater than @xmath6 .
one possibility for reconciling these differences has been the recent success of warm absorber models for characterizing the x - ray absorption and the associated uv absorption lines in 3c 351 and ngc 5548 ( mathur et al . 1994 ; mathur et al . 1995 ) . in such models
the absorption arises in gas photoionized by the central engine ( e.g. , netzer 1993 ; krolik & kriss 1995 ) . the x - ray absorption is dominated by highly ionized species of heavy ions ( e.g. , o vii and o viii ) .
the total gas columns can be quite high ( @xmath1@xmath2 ) , with relatively low columns in the lower ionization species responsible for the uv absorption .
warm absorber models with a reflection component can fit the x - ray spectrum of ngc 4151 ( weaver et al .
1994a , b ) .
kriss et al .
( 1995 ) find that similar models can also account for the high ionization lines in ngc 4151 ( e.g. , o vi , n v , and c iv ) , but they can not simultaneously match the particularly strong absorption in lower ionization species such as h i , c iii , and si iv .
they conclude that a single - zone warm absorber is insufficient . to search for absorption components that might possibly be identified with the x - ray absorbing gas
, i examined archival high resolution ghrs spectra of the c iv and mg ii line profiles in ngc 4151 .
fig.1 shows the spectrum of ngc 4151 in the c iv region with 14 @xmath7 resolution obtained in 8486 s using grating g160 m of the ghrs on 28 october 1994 . a model consisting of an underlying power law continuum , three broad gaussian emission lines , and 8 c iv absorption line doublets fits the data well and gives @xmath8 for 1800 points and 50 free parameters .
although the deepest and broadest c iv doublet is saturated , the bottom of the line profile is not black .
either this gas only partially covers the source ( at the 90% level , both continuum and broad line ) , or 10% of the continuum flux is scattered around the absorbing region back into our line of sight .
narrow - line emission is visible on the red side of the c iv absorption trough .
this emission is apparently unabsorbed by the broad absorbing gas ; a final layer of absorbing gas , however , lying at the systemic velocity of ngc 4151 , absorbs the core of the narrow - line profile .
this is presumably the ism or halo of ngc 4151 .
the spectrum of the mg ii region at 10 @xmath7 resolution obtained in a 1414 s integration with grating g270 m of the ghrs on 29 october 1994 is shown in fig.2 .
the best fit to the modeled emission and absorption profile gives @xmath9 for 1438 points and 22 free parameters .
as with c iv , the mg ii emission was modeled with 3 gaussians .
seven mg ii absorption doublets are required .
table 1 gives the velocities , equivalent widths , doppler parameters , and column densities of each of the absorption components fit in the c iv and the mg ii spectra .
& & & & & & & & + & & + & & & & & & & & + # & @xmath10 & ew & _ b _ & @xmath11 & @xmath10 & ew & _ b _ & @xmath12 + & @xmath13 & ( ) & @xmath13 & @xmath14 & @xmath13 & ( ) & @xmath13 & @xmath14 + & & & & & & & & + 1 & @xmath15 & 0.514 & 294 & @xmath16 & & & & + 2 & @xmath17@xmath18 & 0.120 & @xmath19 & @xmath20 & @xmath21 & 0.143 & @xmath22 & @xmath23 + 3 & @xmath17@xmath24 & 0.642 & 203 & @xmath25 & & & & + 4 & @xmath26@xmath27 & 0.310 & @xmath28 & @xmath29 & @xmath17@xmath30 & 1.259 & @xmath31 & @xmath32 + 5 & @xmath33 & 0.083 & @xmath34 & @xmath35 & @xmath36 & 0.052 & @xmath37 & @xmath38 + 6 & @xmath39 & 1.026 & 163 & @xmath40 & @xmath41 & 1.116 & 235 & @xmath42 + 7 & @xmath43 & 4.018 & 234 & @xmath44 & @xmath45 & 0.852 & 176 & @xmath46 + 8 & & & & & @xmath47 & 0.329 & @xmath48 & @xmath49 + 9 & @xmath50 & 0.407 & @xmath28 & @xmath51 & @xmath52 & 0.134 & @xmath53 & @xmath54 +
for the absorption components intrinsic to ngc 4151 , i assume that the gas is photoionized by the active nucleus .
computing photoionization models similar to those discussed by krolik & kriss ( 1995 ) and kriss et al .
( 1996 ) , i search for ionization parameters and total column densities that match the mg ii and c iv columns seen in the data .
table 2 summarizes the column density ratios of each of the absorption components and the matching ionization parameters and total column densities .
the velocities are now relative to the systemic velocity of ngc 4151 ( @xmath55 , mundell et al .
1995 ) . & & & & + # & @xmath56 & @xmath57 & log _ u _ & log @xmath58 + & @xmath13 & & & @xmath59 + & & & & + 1 & @xmath60 & @xmath61 & @xmath62 & + 2 & @xmath63 & 0.12 & @xmath64 & 18.3 + 3 & @xmath65 & @xmath61 & @xmath62 & + 4 & @xmath17@xmath66992 & 3.73 & galactic & 20.3 + 5 & @xmath17@xmath66830 & 0.060 & @xmath67 & 18.1 + 6 & @xmath17@xmath66805 & 0.085 & @xmath68 & 18.2 + 7 & @xmath17@xmath66321 & 0.004 & @xmath69 & 19.9 + 8 & @xmath17@xmath66193 & @xmath70 & @xmath71 & 17.018.0 + 9 & @xmath26@xmath661 & 0.026 & @xmath72 & 18.6 + note that all the absorbing systems have fairly low ionization parameters .
none of the systems in which mg ii absorption is visible is a good candidate for association with the warm x - ray absorbing gas , which typically has high ionization parameters @xmath73 and high total column densities log @xmath74 ( weaver et al .
1994a , b ) . while components 1 and 3 might be possible candidates , note that component 1 is visible only at this single epoch .
it is absent from all other ghrs observations at both higher and lower flux levels ( weymann et al .
observations of higher ionization species such as si iv or n v are required to set more stringent constraints on the ionization parameters and the total column densities of components 1 and 3 .
bromage , g. , et al .
1985 , mnras , 215 , 1 kriss , g. a. , et al .
1992 , apj , 392 , 485 kriss , g. a. , et al .
1995 , apj , 454 , l7 kriss , g. a. , et al .
1996 , apj , 467 , 622 krolik , j. h. , & kriss , g. a. 1995 , apj , 447 , 512 mathur , s. , et al .
1994 , apj , 434 , 493 mathur , s. , et al .
1995 , apj , 452 , 230 mundell , c. g. , et al .
1995 , mnras , 272 , 355 netzer , h. 1993 , apj , 411 , 594 weaver , k. , et al . 1994a , apj , 423 , 621 weaver , k. , et al .
1994b , apj , 436 , l27 weymann , r. j. , et al .
1997 , this volume | observations of the c iv and mg ii absorption lines in the seyfert 1 galaxy ngc 4151 obtained with the ghrs in october 1994 are presented .
the data from the stsci archive show multiple broad and narrow components in both species .
in addition to galactic absorption , four narrow and four broad systems associated with ngc 4151 are identified .
two broad systems dominate the total equivalent width , and their mean blueshift and width are comparable to the broad lyman line and continuum absorption seen in far - uv spectra from the hopkins ultraviolet telescope . narrow - line c iv emission is present on the red side of the broadest absorption trough , and narrow absorption at the systemic velocity of ngc 4151 , presumably in its own ism , absorbs the core of the narrow emission line .
strong mg ii absorption is present in all but two velocity systems .
ratios relative to the corresponding c iv components suggest a low ionization parameter for the absorbing gas : @xmath0 .
this makes none of the identified uv absorption systems a good candidate for association with the warm x - ray absorbing gas . |
the understanding of the phase behavior of fluids confined in narrow regions , including the fluid mediated interactions , is of crucial importance in the physics of fluids in porous media , for colloidal physics , for many applications and modern technologies such as lubrication , adhesion or friction , in micro and nano - fluidics as well as for the proper interpretation of surface force experiments @xcite . in the current article the order parameter profile and its response functions to an
externally applied ordering field @xmath0 , as well as the free energy will be investigated as functions of both the temperature @xmath1 and @xmath0 for the three - dimensional continuum mean - field ising model with a film geometry @xmath2 .
we will consider the full @xmath3 plane for the case when the bounding surfaces of the system strongly prefer the ordered phase of the system which can be a simple fluid , magnetic system close to their respective critical point , or a binary liquid mixture close to its demixing point . this is a standard model
within which one studies phenomena like critical adsorption @xcite , wetting or drying @xcite , surface phenomena @xcite , capillary condensation @xcite , localization - delocalization phase transition @xcite , finite - size behavior of thin films @xcite , the thermodynamic casimir effect @xcite , etc .
one normally derives the results for @xmath4 analytically @xcite while the @xmath0-dependence is studied numerically either at the bulk critical point of the system @xmath5 , or along some specific isotherms see , e.g. , @xcite . in the current study we will present analytical results for the @xmath0-dependence of the model and
will provide results for the full @xmath3 dependences of the order parameter , local and total susceptibilities in the @xmath3 plane . in what follows
we will mainly use the magnetic terminology but when considering capillary condensation we will also use that one of a simple fluid system in order better to reflect the physics of the obtained exact mathematical results . in order to be more specific
let us remind some facts and definitions pertinent to the above mentioned problems .
if a fluid , or a magnetic system possesses a bounding surface its phase behavior as a function of its temperature @xmath1 , excess chemical potential @xmath6 and the material characteristics of the surface are essentially enriched near the surface one can have , e.g. , phenomena of wetting or drying @xcite . in the vicinity of the bulk critical temperature @xmath7 of the bulk system , one observes a diversity of surface phase transitions @xcite of different kind in which the surface orders before , together , or after ordering in the bulk of the system , which is known as normal ( or extraordinary ) , surface - bulk and ordinary surface phase transitions . for a simple fluid or for binary liquid mixtures the wall generically prefers one of the fluid phases or one of the components . in the vicinity of the bulk
critical point the last leads to the phenomenon of critical adsorption @xcite .
obviously , the surface breaks the spatial symmetry of the bulk system .
the penetration depth of the effects due to the existence of a bounding surface in the body of the system is set by the correlation length @xmath8 of the order parameter ; @xmath8 becomes large , and theoretically diverges , in the vicinity of the bulk critical point @xmath9 : @xmath10 , @xmath11 , and @xmath12 , where @xmath13 and @xmath14 are the usual critical exponents and @xmath15 and @xmath16 are the corresponding nonuniversal amplitudes of the correlation length along the @xmath17 and @xmath0 axes . when at least one of the spacial extensions of the system is finite , as in the @xmath2 film geometry we consider in the current article , one terms the corresponding system a finite system .
if in such a system @xmath8 becomes comparable to @xmath18 , the thermodynamic functions describing its behavior depend on the ratio @xmath19 and take a scaling form given by the finite - size scaling theory @xcite .
one observes , _
inter alia _ ,
shift of the critical point of the system @xcite from @xmath7 to @xmath20 .
when in the finite system there is a phase transition of its own @xmath20 is a true critical point .
below @xmath7 , if the confining walls of the film are of the same material , the capillary condensation occurs @xcite where , e.g. , the liquid vapor coexistence line shifts away from the bulk coexistence into the one - phase regime .
this coexistence line of first order transitions ends at a point @xmath20 , which is normally identified with the capillary condensation point @xmath21 that , on its turn , is considered to correspond to the highest temperature at which the entire capillary fills with liquid . in the current article
we will demonstrate that @xmath22 is not always true .
we will show that , within the studied model , @xmath21 differs from @xmath20 on a scale determined by @xmath23 .
as already stated above , near a confining wall the symmetry between the two phases of a simple fluid or between the two components of the binary liquid mixture is violated in that one of these phases or components is preferred by the boundary .
thus , the order parameter profile , the density or the composition , becomes a function of the perpendicular coordinate @xmath24 .
this can be modeled by considering local surface fields @xmath25 and @xmath26 acting solely on the surfaces of the system .
when the system undergoes a phase transition in its bulk in the presence of such surface ordering fields one speaks about the `` _ normal _ '' transition @xcite .
it has been shown that it is equivalent , as far as the leading critical behavior is concerned , to the `` _ extraordinary _ '' transition @xcite which is achieved by enhancing the surface couplings stronger than the bulk couplings . in the remainder of this article
we will use the surface field picture .
it has been demonstrated @xcite that when @xmath27 for the leading critical behavior of the system is sufficient to investigate the limits @xmath28 . obviously , there are two principal sub - cases @xmath29 , and @xmath30 corresponding to @xmath31 and @xmath32 .
one usually refers to the former case as the @xmath33 boundary conditions and to the latter case as the @xmath34 boundary conditions . in the current article
we will be only dealing with the behavior of the system under @xmath33 boundary conditions .
for such a system the finite - size scaling theory @xcite predicts : * for the magnetization ( order parameter ) profile @xmath35 where @xmath36 * for the local ( layer ) susceptibility profile @xmath37 with @xmath38 ; * for the total susceptibility @xmath39 one has @xmath40 in eqs .
( [ mfss ] ) ( [ chifss ] ) , @xmath41 and @xmath42 are the critical exponents for the order parameter and the susceptibility ( compressibility ) , the quantities @xmath43 and @xmath44 are nonuniversal metric factors that can be fixed , for a given system , by taking them to be , e.g. , @xmath45^{1/\nu}$ ] , and @xmath46^{\delta/\nu}$ ] .
since the ising system with a film geometry @xmath2 possesses a critical point @xmath20 of its own with coordinates @xmath47 the scaling functions @xmath48 and @xmath49 will exhibit singularities near this point . for example @xmath50 where the subscript in @xmath51 reminds that @xmath51 is the critical exponent of the two - dimensional infinite system that is to be distinguished from the corresponding exponent @xmath52 for the three dimensional bulk system . in the current article
we will derive new exact analytical results for the scaling functions @xmath53 and @xmath49 for the ginzburg - landau ising type mean - field model .
let us recall that in the mean - field approximation @xmath54 , @xmath55 and @xmath56 .
for the version of the model considered here @xmath57 and @xmath58{3}$ ] @xcite .
we begin our study by presenting a short definition of the model that will help us to introduce some of the notations used further in the article .
let us consider an ising type critical system in a parallel plate geometry described by the standard @xmath59 ginzburg - landau hamiltonian @xmath60 = \int_0^l { \cal l}(\phi,\phi ' ) dz,\ ] ] where @xmath61 here : @xmath18 is the film thickness , @xmath62 is the order parameter at the perpendicular position @xmath24 @xmath63 , @xmath11 is the bare reduced temperature with @xmath64 defining the bulk critical temperature , @xmath0 is the external ordering field , @xmath65 is the bare coupling constant and the primes indicate differentiation with respect to the variable @xmath24
. normally , one adds to the right - hand side of eq .
( [ fviafising ] ) a surface - type term with parameters used to impose the boundary conditions on the system .
we will do that by simply requiring the behavior of the order parameter at the boundaries of the system at @xmath66 and @xmath67 to be of a given prescribed type .
the extrema of the functional @xmath68 are determined by the solutions of the corresponding euler - lagrange equation @xmath69 which , on account of eq .
( [ fdefising ] ) , reads @xmath70+h=0.\ ] ] multiplying the above equation by @xmath71 and integrating over @xmath24 one obtains the following first integral of the system @xmath72 where @xmath73 is the constant of integration . in the present article
we choose the so - called @xmath33 boundary conditions : @xmath74 . due to the symmetry
, under such boundary conditions one shall have that @xmath75 .
it is easy to determine the general behavior of @xmath76 near the boundaries for any fixed finite values of @xmath17 and @xmath0 . since @xmath77 near the boundaries then , say , for the left boundary , eq . ( [ isingstress ] ) becomes @xmath78 solving this equation leads to @xmath79 where @xmath80 is the position of the boundary ( in the case considered @xmath81 ) .
note that this leading behavior of the order parameter profile near the boundary does not depend neither on @xmath17 , nor on @xmath0 . from eq .
( [ op_near_z0 ] ) it follows that the integral in eq .
( [ fviafising ] ) diverges .
thus , when a comparison of the values of @xmath68 for different states of the system is needed either some cut - off of the system near the boundaries is necessary , or some special procedure shall be devised . from eq .
( [ phieqalone ] ) , using the definition for the local layered susceptibility @xmath82 one obtains that @xmath83 fulfills the relation @xmath84 on general grounds , as well as from eq .
( [ op_near_z0 ] ) , for a system with @xmath33 boundary conditions one immediately obtains @xmath85 combining eqs .
( [ op_near_z0 ] ) and ( [ eqcontsrchimt ] ) leads to @xmath86 when @xmath87 .
in terms of the scaling variables @xmath88 @xmath89 with @xmath54 and @xmath55 , eq .
( [ phieqalone ] ) for the order parameter profile takes the form @xmath90-\frac{\bar{x}_h}{2}.\ ] ] the solutions of eq .
( [ msaclingeqa ] ) determine the extrema of the energy functional @xmath91 where @xmath92 ^ 2 + x_m^4(\zeta)+ x_t x_m^2(\zeta)-\bar{x}_h x_m(\zeta)\ ] ] is the energy density .
hereafter , the primes indicate differentiation with respect to the variable @xmath93 which , as follows from eq .
( [ isvar1 ] ) , varies in the closed interval @xmath94 $ ] . according to eq .
( [ isingstress ] ) the first integral of eq .
( [ msaclingeqa ] ) reads @xmath95 ^ 2 = p[x_m ] , \qquad p[x_m]=x_m^4(\zeta)+x_t x_m^2(\zeta ) -\bar{x}_h x_m(\zeta)+\varepsilon,\ ] ] where @xmath96 denotes the respective constant of integration .
when @xmath4 the magnetization profile is known exactly @xcite in terms of two mutually related implicit equations : 1 . when @xmath97 @xmath98}{{\rm sn}[2 k(k)\zeta;k]},\end{aligned}\ ] ] where @xmath99 is to be determined from @xmath100 ^ 2(2k^2 - 1);\ ] ] 2 .
when @xmath101 @xmath102},\end{aligned}\ ] ] where @xmath103 is to be determined from @xmath104 ^ 2(\bar{k}^2 + 1).\ ] ] here @xmath105 is the complete elliptic integral of the first kind , @xmath106 and @xmath107 are the jacobian delta amplitude and the sine amplitude functions , respectively .
the bulk critical point @xmath5 corresponds to @xmath108 .
note , however , that within the mean - field theory the magnitude of the variable @xmath109 is not universal , in that it is multiplied by the nonuniversal factor @xmath110 see eq .
( [ isvar2 ] ) .
finally , we stress that the choice of two parameterizations ( see eqs .
( [ tk ] ) and ( [ tkb ] ) ) of the scaling functions in eqs .
( [ mz ] ) and ( [ mzd ] ) , is just for convenience ; it allows one to avoid using imaginary values of @xmath111 and @xmath112 .
indeed , one can transfer any of the set of equations into the other one .
for example , defining @xmath112 as @xmath113 where @xmath114 , and taking into account the following properties of the elliptic functions @xcite @xmath115 and @xmath116 one can easily check that the pair of equations ( [ mz ] ) , ( [ tk ] ) is equivalent to the pair of equations ( [ mzd ] ) , ( [ tkb ] ) . in order to utilize the symmetry of the problem it is helpful to move the coordinate frame so that the origin of the @xmath93 axis is at the midpoint of the film @xcite .
taking into account that @xcite @xmath117}{{\rm sn}[u+k(k);k]}=\frac{k'}{{\rm cn}(u;k ) } , \qquad \mbox{and } \qquad { \rm cn}(iu;k')=1/{\rm cn}(u;k)\ ] ] from eq .
( [ mz ] ) one obtains @xcite @xmath118\ ] ] where @xmath119 $ ] and @xmath120 since @xmath121 , one has @xmath122 .
( [ xmmiddle ] ) is the simplest representation of the order parameter profile in a system with strongly adsorbing boundaries we are aware of .
( [ xmmiddle ] ) , normalized per its value in the middle of the system @xmath123 for @xmath5.,width=288 ] the typical behavior of @xmath124 is shown on figure [ fig : xm ] for three different temperatures : at , well below , and well above the bulk critical temperature @xmath7 . when @xmath125 the study of the order parameter ( magnetization ) profiles was carried out numerically @xcite .
below , however , we shall give an analytical representation of the foregoing profiles by means of weierstrass elliptic functions , which is quite similar to that presented above for @xmath4 up to the lack of the parametrization through the elliptic modulus achieved in that case , see eqs .
( [ mz ] ) ( [ tkb ] ) .
first , let us recall that we are interested in real - valued solutions @xmath126 of eq .
( [ msaclingeqa ] ) , corresponding to given values of the parameters @xmath127 and @xmath128 , which are smooth in the open interval @xmath129 and satisfy the @xmath33 boundary conditions .
evidently , for each such solution the polynomial @xmath130 $ ] should have at least one real root @xmath131 .
otherwise the considered solution would be either strictly increasing or strictly decreasing , contrary to the required boundary conditions , since its derivative @xmath132 would be either strictly positive or strictly negative as implied by the particular form of eq .
( [ firstinta ] ) .
consequently , the constant of integration @xmath133 corresponding to such a solution can be cast in the form @xmath134 now , given a triple of values of the parameters @xmath127 , @xmath128 and @xmath131 , each real - valued solution @xmath126 of eq .
( [ firstinta ] ) can be expressed , following ( * ? ? ?
* , 21.73 ) , in the form @xmath135 here , @xmath136 is the weierstrass elliptic function , @xmath137 and @xmath138 are the invariants of the polynomial @xmath130 $ ] , which according to ( * ? ? ?
* , 21.73 ) and eq .
( [ intconst ] ) read @xmath139 @xmath140.\ ] ] note that each function of form ( [ wsa ] ) has the following important properties .
first , its graph in the @xmath141 plane is symmetric with respect to the line parallel to @xmath142 axis and passing through the point @xmath143 .
this is because the weierstrass elliptic functions have the property @xmath144 .
next , @xmath145 since the function @xmath146 has a second - order pole at @xmath147 , i.e. , @xmath148 .
finally , the considered function has a local minimum at @xmath147 if and only if @xmath149 since eqs .
( [ msaclingeqa ] ) and ( [ pr1 ] ) imply @xmath150.\ ] ] let us stress that not any function of the form ( [ wsa ] ) satisfies the required @xmath151 boundary conditions .
actually , a function of form ( [ wsa ] ) corresponding to a given couple of values of the parameters @xmath127 and @xmath128 meets these conditions if and only if @xmath152 is such that : _ ( a ) _ the denominator of the second term in the right hand side of expression ( [ wsa ] ) attains zero at @xmath153 and @xmath154 , which in view of the relation @xmath155 , means @xmath156 where @xmath157 _ ( b ) _
@xmath131 satisfies constraint ( [ eq : condition ] ) , meaning that the function @xmath158 attains its minimal value at @xmath147 , i.e. , at the center of the system .
thus , in order to determine the smooth for each @xmath159 functions @xmath158 of form ( [ wsa ] ) satisfying the considered @xmath33 boundary conditions for given values of the parameters @xmath127 and @xmath160 one should find all the solutions @xmath131 of the respective transcendental equation ( [ treq_text ] ) , which are such that constraint ( [ eq : condition ] ) is fulfilled .
any such function will represent an order parameter profile satisfying the @xmath33 boundary conditions . in the cases in which the parameters @xmath127 and @xmath160 are such that there is more than one value of the parameter @xmath152
satisfying the above requirements , i.e. , there is more than one order parameter profile satisfying the @xmath33 boundary conditions , on physical grounds we chose the one that minimizes the truncated energy @xmath161 were @xmath162 is a small positive number , i.e. , @xmath163 .
we work with the truncated , instead with the full energy , since the integral ( [ afunctional ] ) determining the energy @xmath164 of the states of the system is divergent .
below we justify this procedure in a mathematically rigorous way . before proceeding to that ,
let us introduce an approximation of the considered order parameter profiles near the singular point @xmath165 .
given @xmath127 , @xmath128 and @xmath166 , the solution of eq .
( [ firstinta ] ) , which is unique , can be approximated near the singular point @xmath165 by the function @xmath167 indeed , the substitution @xmath168 in eq .
( [ firstinta ] ) gives @xmath169 ^ 2 - \tilde{x}_m^4(\zeta)-x_t \tilde{x}_m^2(\zeta ) + \bar{x}_h \tilde{x}_m(\zeta)-\varepsilon= \left(\frac{\varepsilon x_t } { 10}+\frac{3\bar{x}_h^2}{32}-\frac{31 x_t ^3}{1080}\right ) \zeta^2+{\cal o}(\zeta^ { 3}).\ ] ] consequently , using the approximate solution @xmath170 of eq .
( [ firstinta ] ) , given by eq .
( [ fismall_z_behavior_of_xm ] ) , one can approximate the energy density ( [ fdefisingmscalinga ] ) near the singular point @xmath165 as @xmath171 next , using the symmetry of the energy density with respect to the point @xmath172 , implied by the symmetry of the general solution ( [ wsa ] ) with respect to this point and eq .
( [ fdefisingmscalinga ] ) , we rewrite the energy ( [ afunctional ] ) in the form @xmath173 now , let @xmath174 and @xmath175 be two different values of the parameter @xmath131 determining two different states of the system for same values of the parameters @xmath127 and @xmath160 .
then , using near the singular point @xmath165 the approximate energy density ( [ approxed ] ) corresponding to the approximate solution ( [ fismall_z_behavior_of_xm ] ) , we observe that @xmath176 \delta + \mathcal{o}(\delta ^{2 } ) \nonumber\end{aligned}\ ] ] and , hence , the difference between the energies of the two regarded states is well defined and determined by the difference between the two respective truncated energies up to terms of order @xmath177 . as it is clear from eq .
( [ eq : energy_fiff ] ) , @xmath178 determines the precision with which we determine the energy differences between any two solutions of the oder parameter problem .
since the value of @xmath178 is on our disposal , we can , at least in principle , determine these energy differences to any prescribed precision .
a numerical verification of the above relation is presented in the appendix . in the remainder , using the derived exact analytical expressions described above in this subsection , we study the behavior of the order parameter profiles in the critical and in the capillary condensation regimes .
it should be stressed , however , that the solutions @xmath131 of the transcendental equation ( [ treq_text ] ) corresponding to given values of the parameters @xmath127 and @xmath160 are determined numerically and those of them that meet the other necessary conditions are identified by inspection .
our first observation concerns the number of the solutions of the considered @xmath151 boundary value problem .
there are values of the parameters @xmath127 and @xmath160 for which we find only one solution of the problem , but there are also regions in the temperature - field plane where there exist three solutions satisfying the @xmath33 boundary conditions , which reduce to two in certain limiting cases .
these alternatives are illustrated in figures [ fig : phd ] and [ fig : ex1 ] . in figure
[ fig : phd ] we show the evolution with @xmath179 ( left ) and @xmath160 ( right ) of the value @xmath131 of the order parameter in the middle of the film for three different values of the temperature @xmath179 and for one value of the field @xmath160 , respectively .
the order parameter profiles corresponding to @xmath180 , @xmath181 and @xmath180 , @xmath182 are depicted in figure [ fig : ex1 ] , where the stable profiles are represented by thick curves . of the order parameter in the middle of the film on @xmath127 and @xmath160 . left : @xmath183 ( dotted ) , @xmath184 ( thick ) and @xmath185 ( dashed ) ; right : @xmath180.,title="fig:",width=249 ] of the order parameter in the middle of the film on @xmath127 and @xmath160 .
left : @xmath183 ( dotted ) , @xmath184 ( thick ) and @xmath185 ( dashed ) ; right : @xmath180.,title="fig:",width=249 ] corresponding to @xmath181 ( left ) and @xmath182 ( right ) , where the stable profile is represented by the thick curve.,title="fig:",width=249 ] corresponding to @xmath181 ( left ) and @xmath182 ( right ) , where the stable profile is represented by the thick curve.,title="fig:",width=249 ] the existence of more than one order parameter profiles for one and the same temperature - field combination is a necessary , but not sufficient , condition for the occurrence of capillary condensation transition .
the latter takes place when at least two of the observed order parameter profiles have the same energy meaning that they coexist .
based on the derived exact analytical expressions we obtain the phase diagram ( see figure [ fig : dp ] , left ) and an unexpected result of the existence of a curve in the temperature - field plane ( see figure [ fig : dp ] , right ) where the system jumps below its bulk critical temperature from a less dense gas to a more dense gas ( see figure [ fig : ggop ] ) before switching on continuously into the usual jump from gas to liquid state in the middle of the system in the capillary condensation regime ( see figure [ fig : re ] ) .
some technical details related to the determination of the data presented in these plots are given in the appendix .
, @xmath186 .
the figure on the right shows the pre - capillary - condensation curve where above @xmath187 and below @xmath188 the system jumps from a less dense gas to a more dense one .
for @xmath189 the order parameter in the middle of the system jumps from a gas to a liquid state.,title="fig:",width=278 ] , @xmath186 .
the figure on the right shows the pre - capillary - condensation curve where above @xmath187 and below @xmath188 the system jumps from a less dense gas to a more dense one .
for @xmath189 the order parameter in the middle of the system jumps from a gas to a liquid state.,title="fig:",width=278 ] we stress here that we term a given state of the system `` gas '' , or `` gas - like '' , if @xmath190 and `` liquid '' , or `` liquid - like '' , when @xmath191 .
we remind that under the @xmath33 boundary conditions studied in the current article one always has @xmath192 for @xmath93 close enough to @xmath193 or @xmath194 , i.e. , one always observe a `` liquid - like '' state near the boundaries of the system .
when one lowers the temperature the following is happening . above @xmath20 one
has a single order parameter profile that satisfies the @xmath33 boundary conditions .
near the phase transitions line there are already three such profiles two of which provide at a point belonging to the phase line and characterized with given @xmath127 and @xmath195 the minimum of the energy of the system , i.e. , they describe the phase coexistence between the gas and the liquid phases . when crossing this line the `` liquid - like '' order parameter profile changes abruptly with the liquid phase intruding deeper into the capillary .
it turns out , however , that in a given temperature range the two liquid branches stemming from the two surfaces of the capillary do not meet in the middle , but a `` gas - lke '' gap still exists there for temperatures @xmath196 .
we call the phase coexistence line for this special case pre - capillary - condensation curve . upon further reduction of the temperature or increase of the magnitude of the negative external field the density of the fluid in this
gap continuously increases reaching its liquid value .
thus , if one defines the capillary condensation temperature @xmath21 as the highest one at which the entire capillary fills with liquid one will obtain @xmath21 that differs from @xmath20 on a scale determined by @xmath23 .
of course , this is a result that follows within the model considered and will be desirable to check if it is a specific feature of the model or if it can be experimentally verified . and @xmath197.,title="fig:",width=249 ] and @xmath197.,title="fig:",width=249 ] and @xmath184.,title="fig:",width=259 ] and @xmath184.,title="fig:",width=259 ]
with respect to local susceptibility @xmath198 with @xmath199 , @xmath200 in the model under consideration , from eqs .
( [ localsusdefmt ] ) and ( [ nscafunchilocmt ] ) one derives @xmath201 in particular , for the local susceptibility in the middle of the system one has @xmath202 where the dot indicates differentiation with respect to the variable @xmath203 . according to eq .
( [ eqcontsrchimt ] ) , @xmath204 satisfies the equation @xmath205x_\chi(\zeta)=-1 . \label{eqxchi}\ ] ] on the other hand , differentiating the first integral ( [ firstinta ] ) of the order parameter equation with respect to @xmath160 and taking into account eqs .
( [ msaclingeqa ] ) and ( [ intconst ] ) , one obtains @xmath206 where @xmath207 \nonumber \\ & = & x_{m0}(\bar{x}_{h } ) -2\dot{x}_{m0}(\bar{x}_{h } ) x_m''(1/2|x_t,\bar{x}_h).\end{aligned}\ ] ] the derivation of the solution of the linear first - order ordinary differential equation ( [ mseq20 ] ) which meets the condition @xmath208 is straightforward and so we can express the local susceptibility @xmath209 through the order parameter @xmath210 in the following explicit form @xmath211 ^ 2 } dw.\ ] ] starting from eq .
( [ scalingfunctionsusceptibilitylocal ] ) one can also determine the function @xmath212 . obviously , eq . ( [ scalingfunctionsusceptibilitylocal ] )
can be written in the form @xmath213 and since @xmath208 one derives @xmath214 thus , all the terms in eq .
( [ gs ] ) are completely determined only by means of the scaling function of the order parameter profile @xmath215 and its derivatives .
furthermore , eq . ( [ newexpls ] ) delivers an alternative analytical expression for @xmath204 provided one knows @xmath215 .
the local susceptibility functions corresponding to the pair of order parameter profiles depicted in figure [ fig : re ] that are coexisting at capillary condensation curve are obtained using eqs .
( [ newexpls ] ) and ( [ newexplsconst ] ) and are presented in figure [ fig : msex1 ] . ) coexisting at capillary condensation for @xmath180 and @xmath184.,title="fig:",width=249 ] ) coexisting at capillary condensation for @xmath180 and @xmath184.,title="fig:",width=249 ] from this figure we see that on the capillary condensation curve the local susceptibility might have either one ot two local maxima . the inspection of figures [ fig : re ] and [ fig : msex1 ] let us to conclude that in the case when the local susceptibility is characterized by two symmetrical local maxima they are centered , approximately , around the two gas - liquid interfaces in the system . when @xmath4 one can determine the scaling function @xmath216 ( see eq .
( [ nscafunchilocmt ] ) ) of the local susceptibility in an explicit analytical form @xcite .
one has @xmath217 where @xmath218 ^ 2\right\},\ ] ] and @xmath219 \right.\nonumber \\ & & \left.\qquad \quad + k'{\rm cn}\left(i \frac{x_{m,0}}{k'}\,\zeta;k ' \right ) \left[k'^2+(1 - 2k'^2)\;{\rm dn}\left(i \frac{x_{m,0}}{k'}\,\zeta;k ' \right)2\right]\right\ } \nonumber , \end{aligned}\ ] ] with @xmath220 here @xmath221 is the complete elliptic integral of the second kind .
normalized per value of this function in the middle of the system for @xmath5.,width=268 ] the behavior of the scaling function @xmath204 for three different temperatures
well below , at and well above @xmath7 is shown on figure [ fig : xchitc ] . according to eq .
( [ chifss ] ) , for the scaling function of the total susceptibility @xmath222 one has @xmath223 wherefrom one obtains that @xmath224 [ x_{m}(\zeta ) -a ] } { \left[x_{m}^{\prime } ( \zeta ) \right]^2 } d\zeta.\ ] ] the temperature behavior of the susceptibility for several fixed values of the field scaling variable are given in figures [ fig : ts_gg_gt ] and [ tsh-250 - 50 ] . ,
i.e. , near @xmath20 ( left ) , and @xmath225 , i.e. , near @xmath21 ( right ) , normalized with the total susceptibility@xmath226 at the bulk critical point .
@xmath227 shows a clear singularity at @xmath20 .
the small finite jump of @xmath228 near @xmath21 happens when @xmath127 passes through the pre - capillary condensation line.,title="fig:",width=278 ] , i.e. , near @xmath20 ( left ) , and @xmath225 , i.e. , near @xmath21 ( right ) , normalized with the total susceptibility@xmath226 at the bulk critical point .
@xmath227 shows a clear singularity at @xmath20
. the small finite jump of @xmath228 near @xmath21 happens when @xmath127 passes through the pre - capillary condensation line.,title="fig:",width=249 ] figure [ fig : ts_gg_gt ] illustrates the dependence of the total susceptibility in the vicinity of the points @xmath20 and @xmath21 .
the left sub - figure there shows the variation of the total susceptibility in the vicinity of the critical point @xmath229 of the finite system , while the right one shows its behavior around the capillary condensation point @xmath230 . here
@xmath231 is understood as the highest temperature at which the entire capillary fills with liquid .
figure [ tsh-250 - 50 ] ( left ) and @xmath232 ( right ) well below and well above the critical value of the magnetic scaling variable @xmath233 , correspondingly , normalized with the total susceptibility@xmath226 at the bulk critical point .
, title="fig:",width=240 ] ( left ) and @xmath232 ( right ) well below and well above the critical value of the magnetic scaling variable @xmath233 , correspondingly , normalized with the total susceptibility@xmath226 at the bulk critical point .
, title="fig:",width=249 ] represents the variation of the total susceptibility with the temperature for fields far away from @xmath233 .
the left figure corresponds to @xmath234 and the finite jump of @xmath222 indicates the passing of @xmath127 through the capillary condensation line .
the curve on the right figure demonstrates that @xmath227 , as expected , is smooth when the field @xmath235 is well above @xmath233 . having in mind eqs .
( [ xchigenmt ] ) ( [ c2explmt ] ) , one can also determine @xcite the scaling function @xmath236 of the total susceptibility @xmath237 , where @xmath238 with @xmath199 and @xmath200 for the model considered . the corresponding result for @xmath239
is @xmath240 here @xmath241 is given in eq .
( [ c2explmt ] ) and @xmath127 is to be determined from eqs .
( [ tk ] ) and ( [ tkb ] ) .
normalized per its value at the bulk critical point.,width=268 ] the behavior of @xmath239 is illustrated in figure [ fig : totsuscont ] .
one observes that @xmath49 possesses a maximum above the critical temperature @xmath7 of the bulk system at @xmath242 and the value of the maximum is @xmath243 times higher than the value of the total susceptibility at the critical point .
in the current article we present exact _ analytical _ results for the temperature - field behavior of the order parameter profile and for the behavior of the main response functions local and total susceptibilities , for one of the basic and most studied models in the statistical mechanics the mean - field ginsburg - landau @xmath59 model . we have studied the properties of this model under the so - called @xmath33 boundary conditions for a system with a film geometry in the case when both bounding the system surfaces strongly prefer the liquid phase of the confined fluid system .
we studied both the critical regime @xmath244 , @xmath245 , where @xmath246 , @xmath199 , @xmath247 , and the capillary condensation regime @xmath248 .
the basic new exact result is the one derived for the behavior of the scaling function of the order parameter profile presented in eq .
( [ wsa ] ) , wherefrom one derives expressions ( [ a ] ) ( [ newexplsconst ] ) for the scaling function of the local susceptibility , and eq .
( [ schifss_res ] ) for the total susceptibility .
analytical results for the behavior of these quantities were known before only for the @xmath4 case .
the behavior of the order parameter profile for different values of @xmath1 and @xmath0 is visualized in figures [ fig : xm ] , [ fig : ex1 ] , [ fig : ggop ] and [ fig : re ] , of the local susceptibility in figures [ fig : msex1 ] and [ fig : xchitc ] , and that one of the total susceptibility - in figures [ fig : ts_gg_gt ] , [ tsh-250 - 50 ] and [ fig : totsuscont ] . based on the derived exact analytical expressions we obtained the phase diagram
( see figure [ fig : dp ] , left ) and the coordinates of the critical point @xmath229 which are in excellent agreement with those determined in @xcite , see fig 13 therein @xcite .
we observed that along the coexistence line between @xmath20 and the the capillary condensation point @xmath230 the system jumps from a less dense gas to a more dense gas ( see figure [ fig : ggop ] ) before switching on continuously into the usual jump from gas to liquid state in the middle of the system in the capillary condensation regime
see figure [ fig : re ] .
this is an unexpected theoretical result that calls for an experimental check - up one shall see if it is a theoretical artifact of the considered model , or corresponds to experimentally observable phenomena . closing this discussion , let us also mention that the mean - field solutions are exact for the critical behavior of systems with dimensionality @xmath249 ( apart from some logarithmic corrections for @xmath250 ) .
next , these solutions serve as a starting point for more sophisticated analytical techniques like the renormalization group calculations utilizing the @xmath96-expansion @xcite . thus
, our results shall be also helpful for such future theoretical considerations .
we wish to thank j. rudnick , s. dietrich , r. evans and a. maciek for helpful comments and the critical reading of the manuscript of this article .
in the current appendix we present a numerical verification of eq .
( [ eq : energy_fiff ] ) and provide some technical details related to the determination of the numerical results presented in some of the plots in the current article . as already stated in the main text , using eq .
( [ eq : energy_fiff ] ) the difference @xmath251 between the energies of two states is determined by the difference between the two respective truncated energies up to terms of order @xmath177 , i.e. @xmath252 where @xmath253 the relation ( [ eq : deltae_a ] ) means that i ) @xmath178 determines the precision with which we determine the energy difference @xmath251 between any two solutions of the oder parameter problem and ii ) that @xmath254 . a numerical verification of eq . ( [ eq : energy_fiff ] )
is presented in figure [ fig : deltaevolution ] . between the truncated energies of the two competing states for @xmath255 at @xmath256 ( left ) and @xmath257 ( right ) .
, title="fig:",width=274 ] between the truncated energies of the two competing states for @xmath255 at @xmath256 ( left ) and @xmath257 ( right ) .
, title="fig:",width=278 ] this figure comprises two typical examples of the evolution of @xmath258 as a function of @xmath178 for @xmath256 ( left ) and @xmath257 ( right ) .
the choice of @xmath178 is indeed important because choosing @xmath178 too large can lead to a wrong conclusion about the energy difference of the competing states .
as figure [ fig : deltaevolution ] shows , the energy difference is negative for @xmath259 , but becomes positive at @xmath260 and stabilizes below @xmath261 .
thus , one should carefully choose the truncation @xmath178 in equations ( [ trunkatedenergy ] ) and ( [ eq : energy_fiff ] ) in order to ensure that the difference of the truncated energies properly indicates which of the two competing states for a given @xmath262 combination is of less energy . to find such @xmath178 one , e.g. , chooses @xmath263 and computes the difference of the truncated energies for increasing integers @xmath264 till this energy no longer changes sign .
figure [ fig : deltaevolution ] depicts how the value of @xmath265 approaches its limiting value @xmath251 with the decrease of @xmath178 , in accordance with eqs .
( [ eq : energy_fiff ] ) and ( [ eq : deltae_a ] ) .
the insets therein show the variation of the difference @xmath266 with @xmath267 . as we see , this dependence is linear which is exactly what it shall be expected on the basis of eq . ( [ eq : energy_fiff ] ) . between the energies of the two competing states for @xmath268 (
left ; the usual jump from gas - like state to liquid - like state ) , and @xmath269 ( right ; a jump from a gas - like state to a denser gas - like state ) .
the circles indicate the coexistence points for these temperatures.,title="fig:",width=268 ] between the energies of the two competing states for @xmath268 ( left ; the usual jump from gas - like state to liquid - like state ) , and @xmath269 ( right ; a jump from a gas - like state to a denser gas - like state ) .
the circles indicate the coexistence points for these temperatures.,title="fig:",width=268 ] at the end , let us present some clarification remarks about the procedure followed in the determination of the phase diagram given in figure [ fig : dp ] . if , at any fixed @xmath262 , the system possesses two competing states we determine the one which is stable by choosing that one with less energy .
an illustration of the evolution of @xmath265 with the change of the thermodynamic parameters governing the behavior of the system is shown in figure [ fig : eevolution ] .
the point @xmath262 for which @xmath265 vanishes within the chosen precision @xmath178 , is the point that belongs to the phase separation line of the phase diagram .
the last implies that the phase diagram is , of course , also determined within that precision . in the current article , as stated above , we have worked with @xmath270 . in order to observe the correspondence between out results for @xmath20 and the one in ref .
@xcite , one shall take into account the difference in the corresponding variables in which the coordinates are given : @xmath271 and @xmath272 . for the precise definition of @xmath273 and @xmath274
, please consult ref . | we investigate the dependence of the order parameter profile , local and total susceptibilities on both the temperature and external magnetic field within the mean - filed ginzburg - landau ising type model .
we study the case of a film geometry when the boundaries of the film exhibit strong adsorption to one of the phases ( components ) of the system .
we do that using general scaling arguments and deriving exact analytical results for the corresponding scaling functions of these quantities . in addition
, we examine their behavior in the capillary condensation regime .
based on the derived exact analytical expressions we obtained an unexpected result the existence of a region in the phase transitions line where the system jumps below its bulk critical temperature from a less dense gas to a more dense gas before switching on continuously into the usual jump from gas to liquid state in the middle of the system .
it is also demonstrated that on the capillary condensation line one of the coexisting local susceptibility profiles is with one maximum , whereas the other one is with two local maxima centered , approximately , around the two gas - liquid interfaces in the system .
_ keywords _ : exact results , phase transitions and critical phenomena , classical phase transitions ( theory ) , finite - size scaling , phase diagrams ( theory ) * contents * |
On Sunday September 16, 2018, Denise Mueller-Korenek broke the bicycle land speed record of 167 mph, hitting 183.932 mph at Utah's Bonneville Salt Flats. This story about the engineering and logistics behind this crazed effort originally ran on Thursday, September 13.
When you’re trying to become the fastest self-propelled human on the planet, you wouldn’t expect getting going at all to be the hardest part. But Denise Mueller-Korenek rides a bicycle so intense, even she can hardly pedal it. At least, not at the speeds hit by any sane cyclist. Once she’s going Autobahn speeds, though, she can unhook from the drag racing car that tows her off the line and start to crank the gear around. Drafting off the steadily accelerating racer and spinning up the rpm's on the bike’s compound reduction gear, she’ll have two and a half minutes to reach the goal that brought her to Utah’s Bonneville Salt Flats this weekend: set the motor-paced bicycle land speed record. Which right now stands at 167 miles per hour.
Accelerating past the takeoff speed of a Boeing 757 on a bike seems impossible, but a top-flight cyclist riding a remarkable bike and drafting the right vehicle piloted by the right driver can make it happen. That is, as long as everything—from physics to fitness, technology to team—works perfectly.
At 45 years old, Mueller-Korenek may be the ideal candidate. As a junior cyclist she won 13 national championships in road, track, and mountain bike racing, before anxiety led her to quit the sport. She spent the next 20 years running a business, raising three sons, skydiving, and racing Mini Coopers. She returned to bike racing five years ago and won two more age-group national titles. Even now, few men can hold her wheel when she opens up a sprint, says her coach, John Howard, who set a previous record, at 152 mph, in 1985. And she has the technical skills to match her explosive aerobic engine. “She’s a world-class bike handler.”
Howard, who coached Mueller-Korenek when she was a junior, got her back into the sport with a simple truth: No woman had ever attempted a speed record. “That was like a match to gasoline,” says Mueller-Korenek.
This weekend’s attempt comes two years after Mueller-Korenek hit 147.7 mph on her bike at Bonneville, setting the women’s speed record (by virtue of being the first woman to try it). She had planned to go for the all-time mark the next day, but thunderstorms rolled in, drenching the salt flats and nixing her chance. The speedy cyclist has changed a few details since, but the core of her approach hasn’t changed. It’s all about having the right equipment and the right team.
Pedal to the Mental
For a vehicle that will reach such eye-tearing speed, Mueller-Korenek’s KHS bike has the approximate aerodynamics of a chopper motorcycle—the wind-blocking car means the bike can serve other priorities. At 35 pounds and more than 7 feet long, it’s twice the size of a normal bike. The low-slung frame features geometry cribbed from the bike that Dutch cyclist Fred Rompelberg used to set the existing record at 167 mph in 1995. The walls of the hollow carbon-fiber frame tubes are three times thicker than those of conventional frames. The 17-inch tires were swiped from a motorcycle, since no cycling rubber is rated for anything near these speeds. A steering stabilizer and a custom-tuned suspension fork borrowed from downhill racing dampen irregularities in the unpaved salt track. The compound reduction gear—essentially two drivetrains joined together—is five times larger than a conventional racing bike’s top gear. That’s why pedaling from a standstill is like trying to start a car in sixth gear.
At 35 pounds and more than 7 feet long, Mueller-Korenek's KHS bike has motorcycle tires and a compound reduction gear setup optimized for riding at triple-digit speeds. Project Speed
Just as important as the bike is the car. Mueller-Korenek will draft an 800-horsepower Top Alcohol dragster—the same one Rompelberg used. It accelerates more smoothly than the supercharged Range Rover SVR she used in 2016, but its aerodynamic fairing creates a low-pressure draft pocket just 46 inches wide, leaving Mueller-Korenek little lateral maneuvering room. The woman working the gas pedal, however, hasn’t changed.
Shea Holbrook didn’t jump at Mueller-Korenek’s invitation to join her team in 2016. Then 26, she already had a résumé full of four-wheel racing experience. But this was different. “It’s one thing to put me in a bomb that goes 300 mph,” Holbrook says. “Here, I have someone’s life in my hands.” Then she and Mueller-Korenek got on the phone. “It was like we’d known each other for 10 years,” Holbrook says. “This was a meant-to-be friendship.”
That bond matters when a cyclist and driver are trying to go triple-digit speeds within a few feet of each other. “The physics of the draft mean we have to be in perfect harmony,” says Mueller-Korenek. She has to follow closely enough that the negative pressure pocket in the car’s wake helps pull her along. She calls it “the dance.”
The dance floor is the Bonneville Salt Flats, a 30,000-acre salt pan near the Utah-Nevada border, one of the few places in the world with the space and the flat, uniform surface needed for a speed record trial. The Short Course track is 5 miles long. After a few low(er)-speed practice runs, Mueller-Korenek will make as many record attempts as she can in the three-day window at this weekend’s World of Speed, sharing the track with car and motorcycle enthusiasts going for their own records.
To start the run, Mueller-Korenek is attached to the dragster with a tether. It’s a rough way to get going, but it works. “The faster I’m going the more stable I am,” Mueller-Korenek says. “If she drags me up slowly, I’ll fall.” Holbrook will feather the throttle to pull as smoothly and quickly as possible over the first mile, which should get her to 110 mph.
Then Mueller-Korenek will release the tether, and Holbrook will accelerate to around 130 or 140 mph, monitoring Mueller-Korenek’s nonverbal communications via a camera: nods to accelerate, head shakes to back off. A color-coded series of lights on the back of the dragster will show Mueller-Korenek how far they’ve gone, and how much track is left.
To secure the record, Mueller-Korenek—now pedaling around 110 rpm—will have to hold 168 mph between mile markers 4 and 5, where the timing traps measure her average speed. As Holbrook accelerates, the cyclist will push 700 watts for more than a minute to stay inside the draft pocket behind the dragster’s fairing. That’s about what a Tour de France sprinter produces in the final minute of a stage.
Any object in motion creates turbulence. But a bluff body, like this fairing, creates a series of alternating vortices that swirl in its wake. “There’s a back-and-forth sensation,” Mueller-Korenek says. As she drifts back, the oscillation feels like being pushed forward on a swing. “At 130 mph, it’s a little kid push,” she says. “Over 150, it’s like an NBA player giving me a shove.” Her job is to deal with those forces while keeping her 7-foot bike inside the 10-foot pocket of air. At 168 mph.
After a successful junior racing career, Mueller-Korenek left the sport for two decades. She sees this speed record attempt as an effort to make up for time lost—and show what she can do. Project Speed
So it’s obvious things can go wrong in a hurry. If Holbook misses a head shake and Mueller-Korenek can’t hold the draft, the turbulence could force her into a violent crash. She’ll wear a motorcycle helmet, gloves, and a leather-and-Kevlar street-luge suit, but it’s no guarantee of safety. In 1988, seven years before he set the record, Rompelberg crashed at almost 150 mph at Bonneville. He broke 24 bones.
For Mueller-Korenek, though, the risk is worth it. This weekend’s attempt is about unfinished business. An opportunity, as she puts it, to “right the wrong” of how she left cycling for all those years. An opportunity to finish what she started in 2016. And the opportunity to occupy a rare firmament: a woman setting a record historically dominated by men. That’s what drew her to this quest, years ago, when Howard told her no woman had ever attempted it. “How often do you get the chance to be a pioneer, and do something that no one else ever has?”
This time, it’s not just something no woman has ever done; it’s something no one, period, ever has.
More Great WIRED Stories ||||| Tooele County, Utah
“NOW WHAT?” Shea Holbrook shouted. “Now what do we do?”
The 28-year-old race car driver from Florida burst into laughter. She knew it was going to be tough to top the madness she’d just experienced.
Moments... ||||| It took just two minutes on Sunday to prove that Denise Mueller-Korenek is the fastest bicyclist in the world ... two minutes and six long years of training, testing and team-building to set the new paced bicycle speed world record at Utah’s Bonneville Salt Flats.
On Sunday afternoon, the 45-year-old Valley Center resident was officially recorded pedaling an average 183.9 miles per hour over one mile, breaking the existing 167-mph record set in 1995 by Dutchman Fred Rompelberg.
The only person who’s seriously tried to beat him over the past 23 years is Mueller-Korenek, who set the women’s world record of 147.7 mph during her first attempt two years ago.
In a phone interview from Utah on Monday morning, Mueller-Korenek said she was shocked to learn that she’d not only broken Rompelberg’s record, but smashed it by more than 16 mph.
“I was literally stunned,” she said. “I was hoping to land somewhere in the 170s and we just blew right through them. It’s amazing to have this record.”
On Sunday, Sept. 16, Denise Mueller-Korenek, 45, of Valley Center set the paced bicycle speed world record of 183.9 miles per hour at the Bonneville Salt Flats in Utah. (www.mattbenstone.com) (www.mattbenstone.com)
Mueller-Korenek is the first woman to hold the overall world title since the record was first established in 1899 by Charles “Mile-a-Minute” Murphy, when he pedaled a bike in the draft of a steam train at 60 mph.
Over the next 100 years, the record gradually rose as the quality of bicycles improved and the shape of the pacing vehicles and the draft or slipstream they provided changed. Few riders attempt this record because it’s so dangerous. Many have died or suffered severe injuries when they hit their pacing vehicle and fell at high speed.
Mueller-Korenek admits to being an adrenaline junkie who grew up in Encinitas racing bikes and cars. The “crazy factor,” she said, runs high in her family.
She said the only moments when she was truly apprehensive on Sunday were when she almost hit the fairing with her front tire during the final ride and then during the fast deceleration process afterward.
“I was praying to God,” she said. “There was a lot of left and right out there and a few times things creep into your head. At the end, there I was, holding on for dear life.”
Without any device to shield a rider from wind resistance, a human-powered bicycle can travel a maximum of 40 miles an hour on a flat surface. Beginning in 1935, speed cyclists began riding behind pace cars fitted with a fan- or box-shaped wind shield known as a fairing.
The fairing creates a capsule-shaped, resistance-free pocket of air behind the pace car that shrinks in size and pressure the faster the car moves. The trick, Mueller-Korenek says, is staying inside that pocket without hitting the fairing in front or getting sucked out of the pocket from behind.
If you can find the “magic of the dance,” as Mueller-Korenek said she did with her pace driver Shea Holbrook of Florida, the pocket feels like a glove pushing you from behind.
Mueller-Korenek said she had no real perception of speed during her record-making ride because she was so busy trying to stay in the draft behind the fairing and trying to watch for the approaching mile markers.
“It was very rough and a very narrow pocket so I was buffeting back and forth and just trying to stay straight and upright,” she said. “It’s sort of like somebody locking you in a box van with no windows. You hear it start up and you know you’re moving but you have no idea how fast it’s going other than the intense vibration and the sound of the wind.”
Mueller-Korenek has been trained over the past six years by cycling legend John Howard, 70, of Encinitas. The three-time Olympian and Ultracycling Hall of Famer holds 14 cycling world championships and won the 1981 Ironman World Championship. He also set two world records, including the 1985 paced bicycle speed record of 152 mph, which Rompelberg broke a decade later.
Mueller-Korenek and Howard met some 30 years ago when her father hired him to train her for cycling races. Performance anxiety led her to quit competing for decades while she raised three sons and took over the family business, Rancho Santa Fe Security Systems.
Then when she got serious about competing again in 2012, she hired Howard, who dangled the idea of breaking the paced bicycle speed record as an incentive, because he knew from experience that she loved a challenge.
Howard believes women over 40 are more capable of long-distance peak performance than men and Mueller-Korenek also has an attribute known as “fast-twitch muscle fiber,” which allows her to accelerate quickly with power on the bike. This is critical in the unusual track test environment in Utah.
The course at Bonneville is five miles long, three for accelerating and two for decelerating. During the first mile, Mueller-Korenek was hooked to the car — a fairing-modified dragster first used by Rompelberg for his 1995 record — as it accelerated to 100 mph.
At mile two, she detached from the car and gradually accelerated her pedaling behind the car as it climbed to 130 mph. In the third mile, she had to summon the strength to keep pace with the fast-accelerating car. It’s that third mile that track officials monitor for the record average speed.
Mueller-Korenek said the key factor in her success was the trust relationship she has built with pace driver, Holbrook, an accomplished race-car driver.
Holbrook’s car had a dashboard monitor that showed live video of Mueller-Korenek’s distance pedaling behind the fairing. During that third mile, Holbrook said she had the gas pedal floored and still Mueller-Korenek kept pace.
“I couldn’t ask for a better person to literally be on the same wavelength with me, matching me move for move,” Mueller-Korenek said.
To fund the record attempt, Mueller-Korenek formed Project Speed, which helped pay for her bike — a 35-pound, 7-½-foot, low-slung cycle specially adapted for high-speed racing — as well as training expenses and equipment, including the pace car, trailers and gear. She never raised enough money to fund the Utah trip, though, so most of her support team came to Utah and worked at their own expense.
“We didn’t have the budget to do this. We were upside down,” she said. “To have people that believe in you so much they’re willing to take time out of their lives to be here is just awesome.”
The group arrived at Bonneville on Tuesday of last week but suffered a series of setbacks with trailer, speedomoter, tire and weather problems that delayed any test runs until Friday. | – Plenty of cars can't reach 183.9mph. Denise Mueller-Korenek managed it on a bike in the obscure world of "motor-paced cycling," reports the Wall Street Journal. Peddling in a race car's slipstream, the 45-year-old former junior cycling champion smashed the bicycle land speed record of 167mph set by Dutch cyclist Fred Rompelberg in 1995 at Utah's Bonneville Salt Flats on Sunday. "Now I know how Evel Knievel felt," Mueller-Korenek tells the Journal's Jason Gay, who watched her achieve her goal. She was towed behind the dragster for two miles as the driver pushed it to 150mph. Mueller-Korenek then released a tether and peddled in an air pocket that helped propel her. "It's like an NBA player giving me a shove," she tells Wired, which notes the record is faster than the takeoff speed of a Boeing 757. Mueller-Korenek of Valley Center, Calif., also had help from a special carbon-fiber bike fitted with motorcycle tires. Twice the size of a normal bike, it travels up to 130 feet on one pedal stroke, per the Journal. But that says nothing of the work Mueller-Konorek put in while chasing the record over six years, per the San Diego Union Tribune. After hitting 147.7mph as the first woman to try for the speed record in 2016, she broke a shoulder blade in a February 2017 crash, then accidentally shot herself in the leg at a competitive shooting event months later. Coach John Howard—who set the record at 152mph in 1985—pushed her on. Despite a moment of fear Sunday as the bicycle's front tire nearly hit the car, "it all came together," Howard says. |
participatory appraisal : a participatory appraisal was conducted in may 2012 for two hours , by one facilitator and three veterinarians who were dispatched to miyazaki to control the fmd epidemic , to design a questionnaire . prior to the appraisal , all three veterinarians were interviewed individually and were confirmed to have enough understandings on the stress from several different disease control activities in miyazaki . in this appraisal , participants were encouraged to freely express their views about mental stress , and a facilitator recorded their descriptions on sticky - notes during the discussion .
questionnaire survey of mental health : as a pilot study , a self - administered questionnaire was designed based on the participatory appraisal results and was tested using five veterinary volunteers who were dispatched from prefectures other than miyazaki for fmd control . a digitized
, password - secured questionnaire was distributed through the ministry of agriculture , forestry and fisheries ; the ministry of education , culture , sports , science and technology ; prefectural governments ; and the japan veterinary medical association ( see supplementary file 1 ) .
questionnaires were collected electronically at the national center for psychiatry and neurological research between october and december 2012 .
the contents of the questionnaire included personal attributes , affiliations , activities engaged in during the disease control , mental stress and whether the participant was able to talk to someone about the stress from the work .
intensity of mental stress at the time of the survey was measured using ies - r .
impact of event scale - revised ( ies - r ) : ies - r is comprised of 22 items falling into three categories of ptsd associated symptoms ( i.e. , eight intrusion items , eight avoidance items and six hyperarousal items ( see supplementary file 2 ) ) .
it evaluates the severity of stress on a 5-point scale ( from 0 to 4 ) during the previous seven days .
the ies - r is used as an indicator of ptsd , with its cut - off score between 24 and 25 .
when the total ies - r score exceeds the cut - off score and the scores of the above - mentioned three categories are high , it is suggestive of ptsd , whereas a high score in one or two of the three categories suggests partial ptsd which is still of clinical concern .
statistical analysis : statistical analyses were performed using statistical software r , version 3.0.1 . in the univariate analysis of the ies - r scores at the time of survey in 2012 , the effects of sex , participation in the different activities in fmd control , types of the farms engaged in , and having someone to talk to were tested using the wilcoxon rank sum test . the ies - r score was compared between age categories ( 20s , 30s , 40s , 50s and 60 years old ) and between affiliation categories using generalized linear models ( glms ) with quasi - poisson errors . in the multivariable analysis , model simplification was performed using glm with quasi - poisson errors choosing the ies - r score as the response variable and factors with p value less than 0.2 in univariate analyses as explanatory variables .
the proportion of those who talked about stress among those who had stress was compared between different time points using chi - square test .
the questionnaire was distributed electronically by the organizations dispatched their personnel , the number of people received it , and the response rate was unknown .
out of the total respondents , 1.3% ( 11 respondents ) had intense mental stress ( ies - r>=25 ) .
female respondents had a significantly higher ies - r score ( 4.8 ) than males ( 2.7 ; p=0.02 ) .
mean age was 45.8 years old , and the age group of 3050 years old predominated .
the mean ies - r scores were not significantly different among these age groups ( p=0.27 ) .
table 1table 1.the affiliations of the respondents and mean ies - r scoreaffiliationsrespondents(%)mean ies - rp - valuegovernment48655.52.4prefecture35340.33.5<0.01*university242.730.6private company40.57.30.06private veterinary clinics40.500.98retired40.50.30.5total875100*statistical significance ( p<0.05 ) compared to
the majority of respondents were public officers : national government ( 55.5% ) and prefecture ( 40.3% ) employees . during the fmd outbreak , a large number of veterinarians belonging to farmers mutual aid associations participated in the disease control , but they did not participate in the present survey .
p - values in table 1 show the comparisons in the level of ies - r between government and the rest of the categories .
prefectural officers had significantly higher scores ( 3.5 ; p<0.01 ) compared to government officers , and there was no difference between government officers and the rest of the affiliations . among the 486 government officers , 395 ( 81.3% ) were clerical officers , who for the most part did not have a background in veterinary medicine or experience dealing with animals .
government. transition in the reasons for distress before , during and after disease control : before being dispatched to miyazaki , the most common reason for mental stress was lack of information about the expected activities in miyazaki ( n=241 , 27.5% ) . for some participants , the date of dispatch was changed ( n=59 , 6.7% ) , and 2.9% ( n=25 ) had trouble with their home institutions about attending the fmd control effort .
five stresses during fmd control were identified : chain of command , culling , human relationships , physical injury / accident , and restriction of activities due to biosecurity ( table 2table 2.the reasons of mental stress during the fmd control ( n=875)the reasons of mental distressrespondentsexperienced(%)a . chain of commanddisrupted information transfer on the tasks and schedules21925confusion in the chain of command in a farm during culling16118.4confusion among the national , prefectural and municipal chains of commands13415.3b .
human relationshiptroubles in conversations with famers12414.2troubles during clinical fmd detection in farms vaccinated10011.4conflicts between participants except for yourself556.3conflicts among participants at dinner time546.2troubles cause by the difference of sex394.5conflicts between a participant and yourself323.7felt discriminated between veterinarians and livestock technicians313.5d .
restriction of activities due to biosecurityrestriction in entrance to the hotel due to biosecurity151.7restriction of communication with family / home institution101.1restriction of the use of cloths and belongings80.9 ) .
the most common reason identified for mental stress was disrupted information transfer ( 25.0% ) .
the other commonly experienced stresses were troubles with farmers ( 14.2% ) and physical injuries and accidents of other participants ( 10.3% ) .
although not ranked high , 5.7% experienced mental or physical reactions resulted in refusal to cull animals .
it was revealed that there was discrimination between veterinarians and livestock technicians , for example , priority in access to clothes or activities engaged in ( 3.5% ) .
restriction to assure biosecurity was stressful to fewer participants ( table 1e ) . after returning home from miyazaki ,
27 respondents experienced indifference about the fmd outbreak in their home institution ( 3.1% , not shown in table ) .
twenty - one respondents ( 2.4% ) felt anxiety due to fear of being a source of a new outbreak .
participants in fmd control were ordered to stay home for a week before returning to the office , and 19 respondents ( 2.2% ) were stressed because of this .
some participants disclosed sensitive issues experienced during culling on the internet , and 13 respondents ( 1.5% ) were stressed from the thoughtless scandalization .
nine respondents commented in the free description section that they felt guilty about having killed animals .
activities engaged in during the fmd control : table 3table 3.activity engaged during disease control and ies - r score ( n=875)numberengaged in(%)sex ratiomean ies - rp - valueengagedothersculling43049.1103.72<0.01*disinfection of barns32637.320.73.42.5<0.01*disinfection of vehicles 26630.428.42.23.1<0.01*burial10311.8only male3.52.80.05epidemiological survey475.43.74.52.80.3health check of animals404.672.82.90.4transporting animals culled384.3374.62.80.04*vaccination343.910.33.72.80.1fmd diagnosis343.97.52.22.90.1a ) preventive factor . *
statistical significance ( p<0.05 ) . shows the activities engaged in during the disease control and ies - r scores .
p - values show the test significance of ies - r scores between those who engaged in the activity and the others .
the most common activities were culling ( 49.1% ) , disinfection of barns ( 37.3% ) and disinfection of vehicles ( 30.4% ) . in terms of gender
, female veterinarians tended to engage in activities not associated with culling , such as epidemiological surveys , animal health checks and fmd diagnosis ( see lower sex ratios ) .
the activities significantly associated with high ies - r scores were culling ( p<0.01 ) , disinfection of barns ( p<0.01 ) and transporting culled animals ( p=0.04 ) .
although the p - value was just above the significance level ( p=0.051 ) , mean ies - r score of those who engaged in burial of the animals slaughtered was notably high compared to those who did not .
in contrast , disinfection of vehicles was associated with low ies - r scores ( p<0.01 ) . in relation to workplace affiliations , common activities for government officers were disinfection of vehicles ( n=250 , 51.4% ) , disinfection of barns ( 213 , 43.8% ) and culling ( 143 , 29.4% ) , whereas those activities for prefectural officers were culling ( 262 , 74.2% ) , disinfection of barns ( 110 , 31.2% ) and interviews ( 40 , 11.3% ; data not shown in tables ) .
the proportion of respondents engaged in culling was significantly higher among prefectural officers ( 74.0% ) compared to government officers ( 29.4% , x=162.5 , df=1 , p<0.01 ) . among the activities listed in table 3 , the proportion of clerical officers among those who attended was highest for disinfection of vehicles ( 237/266 , 89.1% ) , burial ( 80/103 , 77.7% ) and transporting culled animals ( 29/38 , 76.3% ; data not shown in tables ) .
types of farms : table 4table 4.types of farms engaged in during the disease control and ies - r score ( n=875)type of farmrespondentsies - rp - valuen(%)engagedotherspig farm45451.93.22.4<0.01*beef cattle integrated farm44450.73.42.2<0.01*beef cattle breeding farm40245.93.72.2<0.01*dairy farm19922.73.12.80.4goat farm313.53.82.80.3sheep farm 910.72.9<0.01*a ) preventive factor . *
statistical significance ( p<0.05 ) . shows the types of farms engaged in during the disease control and mean ies - r scores .
p - values show the test significance of ies - r scores between those who engaged in the activity and the others .
large proportions of respondents were at pig farms ( 51.9% ) , beef cattle integrated farms ( 50.7% ) and beef cattle breeding farms ( 45.9% ) .
the mean ies - r score was significantly higher among those who were at pig farms ( 3.2 ) , beef cattle integrated farms ( 3.4 ) and beef cattle breeding farms ( 3.7 ) compared to those who were at other types of farms ( 2.4 , 2.2 and 2.2 , respectively ; p<0.01 ) . among them ,
the highest ies - r score was for those who were at beef cattle breeding farms .
the mean ies - r score was significantly lower among those at sheep farms ( 0.7 ) than those at other farms ( 2.9 , p<0.01 ) .
: at all time periods , respondents who had stress showed significantly higher ies - r scores than those without stress ( p<0.01 ; table 5table 5.mental stress related with fmd during , soon after disease control , and at the time of surveyperiodhad stress / responded(%)ies - rp - valuehad stressno stressduring fmd control391/81148.24.61.1<0.01*after fmd control311/82737.65.41.4<0.01*at the time of survey97/84311.592.1<0.01**statistical significance ( p<0.05 ) . ) .
the proportion of respondents with mental stress was highest during fmd control ( 48.2% ) .
stress significantly decreased soon after finishing ( 37.6% , x=18.4 , df=1 , p<0.001 ) and even more so by the time of the survey in 2012 ( 11.5% , x=152.6 , df=1 , p<0.001 ) . * statistical significance ( p<0.05 ) .
of those who had mental stress , the proportion who had someone to talk to about stress was not significantly different between the period of working on fmd control ( 63.4% ) and soon after ( 66.6% , x=0.6 , df=1 , p=0.4 ) .
however , the proportion significantly declined from soon after finishing the fmd control work ( 66.6% ) to the time of the survey in 2012 ( 43.3% , x=15.9 , df=1 , p<0.001 ) , and the number of respondents with stress was greatly reduced in 2012 ( table 6table 6.mitigating effect of talking about stress to someoneperiodhad someone to talk to / had stress(%)ies - rp - valuehad someonedid not haveduring fmd control248/39163.44.15.30.2after fmd control207/31166.65.25.70.7at the time of survey42/9743.36.6110.04**statistical significance ( p<0.05 ) . ) . during and soon after fmd control , ies - r scores were not significantly different between those who had someone to talk to ( 4.1 and 5.2 ) and those who did not have ( 5.3 ; p=0.2 and 5.7 ; p=0.7 , respectively ) . however , those who did not have someone to talk to had significantly higher ies - r scores ( 11.0 ) than those who had someone to talk to ( 6.6 ) in 2012 ( p=0.04 ; table 6 ) . * statistical significance ( p<0.05 ) .
multivariable analysis results : a multivariable glm included factors with the p value less than 0.2 in univariate analysis : being female ; government and prefectural officers ( private companies were excluded due to the small number ) ; engaged in culling , disinfection of barns , disinfection of vehicles , burial of culled animals , transportation of culled animals , vaccination , and fmd diagnosis ; worked at pig , beef integrated , and beef cattle breeding farms ; experiencing stress related to fmd work during the epidemic , soon after , and in 2012 ; and did not have someone to talk to about stress in 2012 .
four risk factors remained in the final model : transporting culled animals , felt stressed during fmd control and at the time of the survey , and did not have someone to talk to about fmd - related stress at the time of survey ( table 7table 7.multi-variable analysis resultsvariableestimatesep - value(intercept)0.580.320.08transported animals culled0.930.34<0.01*had stress during fmd control1.010.26<0.01*had stress related with fmd at the time of survey1.380.25<0.01*did not have someone to talked to about stress at the time of survey0.640.21<0.01*se : stands for standard errors . * statistical significance ( p<0.05 ) . ) .
statistical significance ( p<0.05 ) . in order to better understand the reason why transporting culled animals was a risk factor for higher ies - r , the association of being a clerical officer as a confounding factor was further examined .
the mean ies - r score of clerical officers ( 2.2 ) was significantly lower than that of the others ( 3.4 ; p<0.001 , wilcoxon rank sum test ) .
however , among those who transported culled animals , the mean ies - r score of clerical officers ( 4.8 , n=29 ) was not significantly different from the others ( 3.8 , n=9 ; p=0.37 ) .
removal of the factor of being a clerical officer from additionally performed multivariable glm , selecting ies - r score as a response variable , and transporting culled animals ( slope of log=0.67 ; p=0.01 ) and being a clerical officer ( slope of log= 0.50 ; p<0.001 ) as explanatory variables changed the slope for transporting animals by 25.3% ( slope of log=0.50 , ( 0.670.50)/0.67=0.253 ) , and this suggested
moderate confounding for being a clerical officer .
this study investigated mental stress of veterinarians , livestock technicians and clerical officers dispatched to miyazaki prefecture two years after attending the fmd control in 2010 , in order to understand the long - term mental health effects of culling large numbers of animals .
it is known that recovery from ptsd depends on individual resilience , and the symptoms can persist several years after the traumatic events among some individuals .
moreover , delayed ptsd may appear in some individuals more than one year after such traumatic events .
our study showed that 1.3% of the respondents had higher ies - r scores than the cut - off point suggesting ptsd , which might be caused by the stress of fmd control .
multivariable analysis identified four risk factors associated with high ies - r score , which endorsed the association between the stress in controlling fmd and poorer mental health status .
having fmd - associated mental stress during the disease control and at the time of the survey were risk factors for high ies - r score . in considering relieving such stress ,
in our study , ies - r scores were not significantly different between those who had someone to talk to and those who did not during and soon after the disease control effort .
this might be due to the common practice of disclosing stress while it is still intense , which has been shown from the data ; a
larger proportion of respondents talked to someone about their stress during ( 63.4% ) and soon after the disease control ( 66.6% , table 6 ) . on the contrary , the majority of participants did not experience persistent effects after two years , and it might have become difficult to disclose this distress to others .
therefore , policy supports may be necessary for persistent or delayed ptsd cases caused by participating in fmd control .
another risk factor in the multivariable analysis was transporting culled animals from the farms to burial yards .
additional statistics have shown the existence of a confounder , i.e. , being a clerical officer .
the mean ies - r score of clerical officers was significantly lower than the other volunteers .
however , the task of transporting culled animals may have been highly stressful for the clerical officers who did not have experience of dealing with animals . from a personal communication with veterinary officers at miyazaki prefecture
, it was found that the drivers of trucks transporting culled animals were hired drivers , but the clerical officers worked on loading and unloading carcasses . according to the qualitative statements reported in locally published reports , many cattle breeding farmers requested that culled cows and their calves be buried together and place an offering of sho - chu whisky and a wreath ; the task , transporting culled animals involved
continuous exposure of the clerical officers to the farmers grief .
also , transporting culled animals from infected premises could potentially cause further spread of the fmd virus , and special attention to biosecurity may have caused high stress . in interpreting the multivariable analysis results ,
a caution must be paid to the fact that culling animals was not a risk factor for a high ies - r score in this study .
the intensive stress of culling animals among veterinarians in the fmd outbreak in miyazaki in 2010 has already been described in several qualitative locally published reports .
this distress was derived from the conflict with their vocational pride to save animals , which has been reported from the fmd outbreak in the u.k . in 2001 ,
on the other hand , all the veterinarians must have known that they would have to cull animals when they volunteered , and they might have been determined to some extent .
there are some factors which should not be ignored , among which were significant in univariate analysis , but did not remain in the multivariable results .
females have been reported to be susceptible to traumatic events in several papers [ 1 , 2 , 5 , 9 , 17 ] , and in our participatory appraisals , it was mentioned that there were no separate changing rooms or gender - sensitive environments .
sex ratios in the activities engaged in during fmd control suggested that some considerations were paid to this . regarding types of animals , being engaged in disease control at pig farms and beef cattle farms
might have been difficult , because ( 1 ) the numbers of pigs were great and the screaming of animals was intense , where animal welfare could not necessarily be achieved , ( 2 ) dealing with large beef cattle
poses the risk of physical injury and ( 3 ) small - scale beef cattle breeding farm workers have much affection toward the animals .
being engaged at sheep farms was a preventive factor ; however , the numbers of sheep farms , and those who engaged in culling were not great , and culling them did not have a significant effect on the mental health of veterinarians . in terms of methodology ,
however , all these participants were well - informed and were considered as key - informants .
therefore , findings from the appraisal were regarded to be robust . regarding the questions associated with mental stress the participants experienced two years prior to the survey , there may have been recall bias , and this is a limitation .
another limitation is that a question regarding the stress of culling animal itself was not asked .
however , this paper has provided detailed and useful records regarding the stress associated with fmd control .
such multi - sector collaboration is called one health , which is critically important in
control of zoonotic disease ( diseases and infections that are naturally transmitted between vertebrate animals and humans [ 8 , 18 ] ) .
we wish such collaborations would be adopted widely by veterinary and health authorities for better preparedness for non - zoonotic animal disease epidemics that involve culling animals for disease control .
| foot - and - mouth disease ( fmd ) occurred in miyazaki , japan , in 2010 , and 290,000 animals were culled .
this paper describes the mental distress of the volunteers who had been dispatched to miyazaki for disease control two years after the epidemic .
it also assesses risk factors for post - traumatic stress disorder ( ptsd ) .
a participatory appraisal and self - administered questionnaire survey were conducted in 2012 for those who were dispatched to miyazaki in 2010 .
the impact of event scale - revised ( ies - r ) was used as an indicator of ptsd , and univariate and multivariable analyses were performed .
of the 875 respondents , 1.3% had higher ies - r scores than the cut - off point ( 25 ) , which is suggestive of ptsd .
mental stresses during and soon after fmd control and after two years were described .
four risk factors associated with high ies - r scores were found : transporting culled animals ( p<0.01 ) , stress during fmd control ( p<0.01 ) and at the time of
the survey ( p<0.01 ) , and lack of someone to talk to about fmd - associated stress at the time of the survey ( p<0.01 ) .
veterinarians , livestock technicians and clerical officers involved in fmd control still suffer from mental stress two years later .
public services should provide an opportunity for them to consult with mental health specialists .
these findings should be used to better prepare workers who deal with infectious diseases of animals , especially when they must be culled .
the establishment of a collaborative framework between veterinary and mental health services is recommended . |
in the past , teaching medical courses was commonly performed via scientific and theoretical classes via teaching aids including textbooks and journals ( 1 ) . however , today changing health care and medical curriculum has made computer - assisted learning more valuable than before ( 2 ) .
in fact , currently the increasing availability of accessing suitable hardware and software for electronic - learning has provided a new horizon for educational institutes ( 3 ) . thus integrating it into the current educational curriculum of universities
the necessity behind this approach is the scientific view about various dimensions of e - learning and the changing process of design based on the existing conditions and logical goals on the country s medical training ( 4 ) .
effective learning above all methods results from decent training , acquired in the proper environment and encouraging creative methods ( 5 ) .
computer - assisted training by educational software such as cd or dvd is considered a fundamental measure to improve medical and dentistry education systems . according to the results derived from some other studies that have used a computer- assisted method training concurrently
has been a reliable and useful method in learning clinical skills and its results have been compared with regular methods ( 6 )
. a very critical role of the computer is organizing and presenting data making the user 's data accessible , control easy and facilitating knowledge acquisition ( 2 ) .
actually , using multimedia boosts the learning process and also applies the learners ' senses ; stimulating their motivation to actively participate besides the training process , making the learners self - organized and self - directed ( 7 ) .
furthermore , it provides the student with an opportunity to fully control the educational content , time and place ( 2 ) . generally speaking
, multimedia facilitates the growth of data - based knowledge spreading ( 5).it seems that the application of multimedia in educational settings has diverse advantages , some of which include using five senses for learning , further practice to become competent , facilitating participation to create inter - conceptual links , facilitating lesson repetition for re - use & cost - effectiveness and the program flexibility versus the learners ' need .
computer - assisted training has its own limitations such as the inability to substitute for teacher , emotional and human interactions , and face - to - face communication occurring in classrooms ( 3 ) .
moreover some critics assume that personal and computerized educational approaches create monotonous and dull educational conditions where there is no spontaneous interaction and communication between the teacher and students or even among the learners ( 4 ) .
various studies have presented different results regarding the use of multimedia for students ' learning .
the study by amanloo aimed to assess and discover web - based instruction strengths and weaknesses in mycology training , showing that in the final test of the course , no meaningful difference to be found between the e - learning and control groups ' students in terms of learning and achievement ( 4).while in the research by aly et al .
( 2003 ) which targeted to compare two multimedia methods and a traditional lecture in training orthodontics ( orthodontia ) among dentistry students , it was declared that although the individuals in multimedia group got a better score , this difference was n't statistically significant ( 2 ) .
in addition , the results by naseri et al . ( 2013 ) aiming to study the effectiveness of using endodontics training on medical students ' knowledge and skill indicated that this educational program application has been useful in terms of scientific endodontics skills learning and or the learners ' knowledge promotion in this field as much as regular demonstration method ( 6 ) . since no study has been performed with the mentioned goal among the dentistry students of guilan medical university so far , in this study , instructional design and assessment of using fixed dental prostheses 2 multimedia in guilan medical university dentistry students of the year 2010 semester has been studied .
first off , instructional content based on a 5-step guide of the virtual labs project at stanford university ( vlpsd ) has been analyzed ( 8) .
first step : ( understand ) : to identify the target group , instructional needs and learning objectives
.
second step : ( design ) : to design instructional content , identify common mistakes of the student , define educational resources , surf the internet , select proper software for producing content , choose motivations to make students participate in learning , and estimate the effectiveness of this method to a traditional one
third step : ( building ) : to build an interactive instructional multimedia
fourth step : ( user testing ) : to achieve learning objectives , being applicable and have content resolution .
fifth step : ( improve ) : to assess multimedia effectiveness through polling the students ' opinion and getting their feedback .
the software used to produce multimedia was ispring suite ver.7.o with audio and visual facilities . to produce multimedia , at first , the fixed dental prostheses 2 educational clip and images were imported to the software , thereafter via using the audio and visual facilities , the teacher explained the lesson subjects and simultaneously , the slide demonstration together with the teacher 's sound and image were presented ( figs . 1 - 3 ) .
content output in sharable content object reference model ( scorm ) format was saved to make learning management system ( lms ) loading possible .
scorm is a standard for educational content that builds upon existing standards for e - learning .
it specifies a framework with which e - learning content is made durable , portable , reusable , interoperable , and accessible ( 9 ) .
the primary objective of the lms is to manage learners , keeping track of their progress and performance across all types of training activities .
the lms manages and allocates learning resources such as registration , classroom and instructor availability , instructional material fulfillment , and online learning delivery ( 10 ) .
sample of instructional content uploaded on lms fixed dental prosthesis lesson multimedia example produced by ispring software fixed dental prosthesis multimedia example produced by ispring software
after designing the instructional multimedia and obtaining the necessary permits , this software was loaded by lms and 69 students in their 5 semester of guilan dentistry school , who were selected via convenience sampling .
two sessions ( 4h out of 20h ) of fixed dental prostheses 2 lesson were assigned for virtual training and applying multimedia . at the end of the course , a researcher - built questionnaire whose validity was determined by 10 authorities ' comments and whose reliability was defined by alpha - cronbach ( =0.82 ) , containing 26 items in two parts : 1 ) demographic information ( 9 items ) and multimedia quality assessment items ( 17 items ) were handed to the students to evaluate the instructional multimedia quality .
statistical comparisons were performed using the t - test for independent samples and the anova test .
meansd age was 24.683.24 years , 43 were women ( 62.4% ) and 26 men ( 37.6% ) the majority of 76.8% ( n=53 ) used the internet at home .
a portion of 33.3% ( n=23 ) were inclined to use multimedia and the internet with an in - person training .
based on the anova and independent t - test , there was no significant relationship between age groups , gender and satisfaction of multimedia quality .
the students ' opinions about the instructional multimedia quality have been given in table 1 .
this study has been conducted with the aim to design and assess fixed dental prostheses 2 multimedia instructional content .
computer - assisted training by software as cd or dvd has been viewed as a fundamental measure to improve medical and dentistry systems .
this method is a powerful tool and the integration of audio and visual data in a multimedia tool format is considered as one of its remarkable advantages ( 6).considering the necessity behind designing multimedia for training dentistry students , fakhry et al .
( 2007 ) stated : due to the limitation of surgery space , oral cavity being small and the nature of the dental procedure , the majority of the students in the clinical situation do nt have the correct view of the procedure details and this impedes learning opportunities .
applying the multimedia procures training through magnified images improving students ' learning ( 11 ) .
learning happens better by the spoken text and images than the written form ( 12,13).in addition , another research , that concluded that it is nt possible to train the practical procedures by the traditional method well and due to this , and in order to make students familiar with practical work and utilizing its results and interpretation , and motivate the students , multimedia based method ( preparing practical lesson plan , practical program plan , practical educational software , using powerpoint and computer ) has been employed ( 14 ) . besides boosting the instructional content quality , designing an instructional multimedia can also promote the students ' independent learning .
as stated in the methods , in this study , instructional content has been designed for reuse in lms in scorm format .
bradley & boyle ( 2004 ) have also designed instructional multimedia for computer courses . in their research , they emphasized on two key goals , namely , designing pedagogic - based instructional multimedia and the potential of reusing multimedia in other universities ( 15 ) , both of which have been observed in this study . in order to follow the schools ' pedagogical principles and taking into consideration the learning objectives ,
the ispring software was employed to produce the multimedia via ; blending the textual , audio and visual facilities using authentic scientific references of dentistry ; so that students achieve maximum learning objectives . in order to reuse the multimedia ,
a scorm output has been applied so that it is possible to use and apply in lms . in other studies , employing scorm in addition to reusing , the instructional content has been shared in various disciplines ; in a way that students could access the instructional content at any a time and place ( 16,17 ) . besides
the students accessing the multimedia content at any time and place , adjusting the learning speed is of the cases studied in the use of multimedia . in multimedia
based training , two general states about speed control are taken into account : 1 ) system - paced education where the instructional content presentation time is carried out by the system and the learners do nt interfere in controlling and adjusting the training speed ; 2 ) self - paced learner education where the training time is determined by the learners .
the studies have suggested that when the self - paced learners control their training presentation speed , their learning is improved ( 18,19 ) .
( 2001 ) asserted that the learners could control the speed animated presentation ( the principle as self - paced ) , compared with the learners receiving the same animation at normal speed and with no control , they had better performance in learning tasks ( 20 ) . in the current research , the latter method , i.e. , self - paced learner has been used and learning speed control was done by the learner , which itself is one of the merits behind using instructional multimedia and through that influences learner 's learning promotion . despite this , some studies have reported conflicting results , for instance , chung ( 2006 ) drew this conclusion after his research that the material presentation speed control by the learner had no effect on learning improvement ( 21 ) .
it seems that in addition to speed control , some other cases such as the learner 's prior knowledge , ability to recognize words and understand the material , the instructional content complexity and difficulty also affect learning ( 22 ) .
the results of this study showed no significant relationship between age , gender and student s satisfaction of multimedia quality . while other studies revealed that men s perception of usefulness was the more significantly direct and more salient than women s in determining behavioral intention to use e - learning .
this finding suggests that men tend to concentrate on the usefulness of a new technology , and that they appear to be fairly
useful content is an important pragmatic factor attracting male users to use e - learning .
pedagogical principles , including principles of developing and packaging content , could be employed in the development and evaluation of e - learning content ( 23,24 ) . also other studies revealed no significant relationship between various ages and e - learning ( 25 ) , while other studies showed significant relationship between different ages and e - learning ( 26,27 ) .
this study extracted revealed that the majority of students have been satisfied with the instructional multimedia .
brett stressed that when using multimedia technology , the students play the leading role since they independently use the multimedia and for this reason , polling the students ' opinions is essential in order to decide about continuing using this method and or including it in the instructional curriculum ( 28 ) .
ozuah ( 2002 ) assumes that the recent advances in ict , genome , supplementary medicine and other cases in medical science and transformation in the instructional curriculum seems inevitable ( 29 ) . in other studies ,
the requirement to change the instructional curriculum due to moving from traditional teacher - oriented method to applying novel student - oriented method has been stressed ( 30,31 ) . before anything else , when implementing every program , it is critical to evaluate the students ' opinions about educational design and content and quality to be assured that the students have the necessary motivation and interest to implement the program ( 31 ) .
brett ( 1996 ) discovered in his study that being satisfied with using the multimedia can be studied from diverse dimensions in different students such as the students ' learning styles , being interested in using technology and computer and it can be assumed that the students learning independently and being highly interested in technology view instructional multimedia as an appropriate method for training ( 28 ) .
this study derived results implying that the majority of students are in agreement with instructional program running through multimedia accompanied with in person training .
the study results by banados ( 2013 ) have also revealed that the students prefer face - to - face instruction and believe that applying online training can lead to the students feeling isolated ( 32 ) . in another research , despite being satisfied with the instructional multimedia , the majority of the students asserted that it is better not to consider using multimedia as a compulsive method in the instructional curriculum rather than applying it along with the conventional method ( 28 ) . here the issue known as blended learning is set forth . blended
learning refers to integrating face - to - face learning in technology based facilities ; combining these two types of learning results in traditional learning promotion ( 33 ) . in other studies , the importance of blended learning and
it 's worth mentioning that face - to - face learning and e - learning each has its own merits and disadvantages and if they are used with each other , they can be highly effective in the students ' learning . in this respect , hoic et al .
( 2009 ) emphasized in their research , that despite having lots of advantages including individual learning , interaction , immediate feedback and online evaluation that computer - assisted learning has , one of the main disadvantages is its inability to keep the student ; in other words , the students ' dropout percentage ( 34 ) .
this matter is of the main reasons behind the bilateral communication importance of e - learning and face - to - face training in order to raise interaction , communication and participation in learning ( 34 ) . in another study ,
the students ' satisfaction with e - learning was lower and they preferred the traditional method .
the students are still inclined to the traditional method and believe that the material presentation and tracking , learning the principles and concepts and clarifying the complicated lesson subjects in the traditional method are more than the blended and internet based method .
this group of students preferred to re - apply the traditional method in the following training course .
the reason for their dissatisfaction was their unfamiliarity with technology and lacking motivation at using novel methods ( 39 ) .
however , in another study , no meaningful relationship has been discovered between the students ' dissatisfaction and familiarity with computer science ( 40 ) .
moreover , in the current study , the instructional multimedia quality was assessed by the students .
the results demonstrated that the majority of the students have announced the produced multimedia quality as good .
in other studies , similar results were also stated , too ( 41,42 ) . on the other hand , in another research
, students had announced the quality of the produced multimedia as average ( 43 ) . of the cases investigated in this study
the study results denoted that the majority of the students were satisfied with the produced multimedia being interactive : student - student and student - content ( 44 ) ; the latter mentioned case is among those not analyzed upon .
most of the studies have shown that the inter - activeness of the content plays a significant role in the students being satisfied with e - learning , their engagement in learning , achieving high learning levels and positive attitude towards distance learning ( 45,46 ) .
another feature assessed in the instructional multimedia is the audio - visual facility and the quality of the images and films in terms of color , graphics , resolution and sound .
the study results revealed that the students were satisfied with all stated cases and these specifications have been exactly observed in the produced software .
other studies results ' about instructional content has suggested that the images presented by the teacher ca n't alone promote the students ' learning . in this study , the conclusion has been drawn that lack of images by the teacher has had no effect on the students ' learning ( 20 ) ; while the teacher 's mouth , lips , eyebrows , nose movements and expressions like laughing and frowning : each has its own meaning , providing additional information for transferring the teacher 's tendencies , emotions and knowledge ( 47,48 ) .
among the specifications of the designed multimedia assessed
are the material s logical order , the material matching the learning objectives and the instructional content accuracy .
the noted cases are of the instructional content design principles which the multimedia format instructional content was nt separated from and these cases have to be considered and observed in multimedia design .
the current study results imply the students ' satisfaction with observing the above cases in the designed multimedia .
the results derived from this study demonstrated that the instructional multimedia design was compatible with lesson objectives and also that audio - visual facilities can have a great effect on meeting the student 's satisfaction . preparing instructional multimedia makes it easy for the students to access the instructional content and study the classroom instructional content . allowing them to review it several times at the proper opportunity .
furthermore , if it is presented through lms , they will be able to study the lesson subject wherever and whenever by just accessing the internet .
using instructional multimedia such as training the procedures via magnified images leads to the students ' learning improvement .
this is especially significant for dentistry students because the limited oral cavity does n't allow them to see all the procedure ' details and via magnified images and films , the necessary training can be presented to them .
besides this , other multimedia facilities such as providing the appropriate questions while presenting the content and giving immediate feedback to the student can promote student - content interaction and increase their learning . | background : above all methods effective learning results from decent training , acquired in the proper environment and encouraging creative methods .
computer - assisted training by educational software is considered a fundamental measure to improve medical and dentistry education systems .
this study aims to design and assess fixed dental prostheses via 2 multimedia instructional contents at the guilan dentistry school .
methods : this is a descriptive and cross - sectional study . first off , the instructional content was analyzed .
the software used to produce multimedia was the ispring suite ver.7.0 . after designing the instructional multimedia ,
this software was loaded by lms .
sixty - nine dentistry students in the 5th semester at guilan dentistry school were selected via convenience sampling . at the end of the course , a structured questionnaire containing 26 items were handed to the students to evaluate the instructional multimedia quality .
results : mean sd age was 24.683.24 years , 43 were women ( 62.4% ) and 26 were men ( 37.6% ) the majority of 76.8% used the internet at home . a portion of 33.3% were inclined to use multimedia and the internet with in - person training .
about 60% declared that multimedia quality as being good .
conclusion : the instructional multimedia designs which are compatible with lesson objectives and audiovisual facilities can have a great effect on the student 's satisfaction . preparing instructional multimedia makes the instructional content easily accessible for students to be able to review it several times at the proper opportunity and if presented through lms they would be able to study the lesson subject wherever and whenever accessing the internet . |
internet of things ( iot ) refers to a technology paradigm wherein ubiquitous sensors numbering in the billions will able to monitor physical infrastructure and environment , human beings and virtual entities in real - time , process both real - time and historic observations , and take actions that improve the efficiency and reliability of systems , or the comfort and lifestyle of society .
the technology building blocks for iot have been ramping up over a decade , with research into pervasive and ubiquitous computing @xcite , and sensor networks @xcite forming precursors .
recent growth in the capabilities of high - speed mobile ( e.g. , 2g/3g/4 g ) and _ ad hoc _
( e.g. , bluetooth ) networks @xcite , smart phones , affordable sensing and crowd - sourced data collection @xcite , cloud data - centers and big data analytics platforms have all contributed to the current inflection point for iot . currently , the iot applications are often manifest in vertical domains , such as demand - response optimization and outage management in _ smart grids _ @xcite , or fitness and sleep tracking and recommendations by _ smart watches and health bands
_ @xcite . the iot stack for such domains is tightly integrated to serve specific needs , but typically operates on a closed - loop _ observe orient decide act ( ooda ) _ cycle , where sensors communicate time - series observations of the ( physical or human ) system to a central server or the cloud for analysis , and the analytics drive recommendations that are enacted on , or notified to , the system to improve it , which is again observed and so on .
in fact , this _ closed - loop _ responsiveness is one of the essential design characteristics of iot applications .
this low - latency cycle makes it necessary to process data streaming from sensors at fine spatial and temporal scales , in _ real - time _ , to derive actionable intelligence .
in particular , this streaming analytics has be to done at massive scales ( millions of sensors , thousands of events per second ) from across distributed sensors , requiring large computational resources .
_ cloud computing _ offers a natural platform for scalable processing of the observations at globally distributed data centers , and sending a feedback response to the iot system at the edge .
recent _ big data platforms _ like apache storm @xcite and spark @xcite provide an intuitive programming model for composing such streaming applications , with a scalable , low - latency execution engine designed for commodity clusters and clouds . these _ distributed stream processing systems ( dsps ) _ are becoming essential components of any iot stack to support online analytics and decision - making for iot applications .
in fact , reference iot solutions from cloud providers like amazon aws and microsoft azure include their proprietary stream and event processing engines as part of the iot analytics architecture .
shared - memory stream processing systems @xcite have been investigated over a decade back for wireless sensor networks , with community benchmarks such as _ linear road _
@xcite being proposed .
but there has not been a detailed review of , or benchmarks for , _ distributed _ stream processing for iot domains . in particular , the efficacy and performance of contemporary dsps , which were originally designed for social network and web traffic @xcite , have not been rigorously studied for _ iot data streams and applications_. we address this gap in this paper .
we develop a benchmark suite for dsps to evaluate their effectiveness for streaming iot applications .
the proposed workload is based on common building - block tasks observed in various iot domains for real - time decision making , and the input streams are sourced from real iot observations from smart cities .
specifically , we make the following contributions : 1 .
we classify different characteristics of streaming applications and their data sources , in [ sec : features ] .
we propose categories of tasks that are essential for iot applications and the key features that are present in their input data streams
we identify performance metrics of dsps that are necessary to meet the latency and scalability needs of streaming iot applications , in
[ sec : metrics ] .
we propose an iot benchmark for dsps based on representative _ micro - benchmark tasks _ , drawn from the above categories , in [ sec : benchmark ] .
further , we design two reference iot applications for _ statistical analytics _ and _ predictive analytics _ composed from these tasks .
we also offer real - world streams with different distributions on which to evaluate them .
4 . we run the benchmark for the popular apache storm dsps , and present empirical results for the same in [ sec : results ] .
our contributions here will allow iot applications to evaluate if current and future dsps meet their performance and scalability needs , and offer a baseline for big data researchers and developers to uniformly compare dsps platforms for different iot domains .
stream processing systems allow users to compose applications as a dataflow graph , with task vertices having some user - defined logic , and streaming edges passing messages between the tasks , and run these applications continuously over incoming data streams .
early data stream management systems ( dsms ) were motivated by sensor network applications , that have similarities to iot @xcite .
they supported continuous query languages with operators such as join , aggregators similar to sql , but with a temporal dimension using windowed - join operations .
these have been extended to distributed implementations @xcite and complex event processing ( cep ) engines for detecting sequences and patterns .
current distributed stream processing systems ( dsps ) like storm and spark streaming @xcite leverage big data fundamentals , running on commodity clusters and clouds , offering weak scaling , ensuring robustness , and supporting fast data processing over thousands of events per second .
they do not support native query operators and instead allow users to plug in their own logic composed as dataflow graphs executed across a cluster . while developed for web and social network applications , such fast data platforms have found use in financial markets , astronomy , and particle physics .
iot is one of the more recent domains to consider them .
work on dsms spawned the linear road benchmark ( lrb ) @xcite that was proposed as an application benchmark . in the scenario , dsms had to evaluate toll and traffic queries over event streams from a virtual toll collection and traffic monitoring system .
this parallels with current smart transportation scenarios
. however , there have been few studies or community efforts on benchmarking dsps , other than individual evaluation of research prototypes against popular dsps like storm or spark .
these efforts define their own measures of success typically limited to throughput and latency and use generic workloads such as enron email dataset with no - operation as micro - benchmark to compare infosphere streams @xcite and storm.sparkbench @xcite uses two streaming applications , twitter popular tag retrieving data from the twitter website to calculate most popular tag every minute and pageview over synthetic user clicks to get various statistics using spark .
stream bench @xcite has proposed 7 micro - benchmarks on 4 different synthetic workload suites generated from real - time web logs and network traffic to evaluate dsps .
metrics including performance , durability and fault tolerance are proposed .
the benchmark covers different dataflow composition patterns and common tasks like grep and wordcount . while useful as a generic streaming benchmark , it does not consider aspects unique to iot applications and streams .
sparkbench @xcite is a framework - specific benchmark for apache spark , and includes four categories of applications from domains spanning graph computation and sql queries , with one on streaming applications supported by spark streaming .
the benchmark metrics include cpu , memory , disk and network io , with the goal of identifying tuning parameters to improve spark s performance .
cepben @xcite evaluates the performance of cep systems based of the functional behavior of queries .
it shows the degree of complexity of cep operations like filter , transform and pattern detection .
the evaluation metrics consider event processing latency , but ignore network overheads and cpu utilization .
further , cep applications rely on a declarative query syntax to match event patterns rather than a dataflow composition based on user - logic provided by dsps . in contrast
, the goal for this paper is to develop relevant micro- and application - level benchmarks for evaluating dsps , specifically for _ iot workloads _ for which such platforms are increasingly being used .
our benchmark is designed to be _ platform - agnostic _ , _ simple _ to implement and execute within diverse dsps , and _ representative _ of both the application logic and data streams observed in iot domains .
this allows for the performance of dsps to be independently and reproducibly verified for iot applications .
there has been a slew of big data benchmarks that have been developed recently in the context of processing high volume ( i.e. , mapreduce - style ) and enterprise / web data that complement our work .
_ hibench _
@xcite is a workload suite for evaluating hadoop with popular micro - benchmarks like sort , wordcount and terasort , mapreduce applications like nutch indexing and pagerank , and machine learning algorithms like k - means clustering .
_ bigdatabench _
@xcite analyzes workloads from social network and search engines , and analytics algorithms like support vector machine ( svm ) over structured , semi - structured and unstructured web data .
both these benchmarks are general purpose workloads that do not target any specific domain , but mapreduce platforms at large .
_ bigbench _
@xcite uses a synthetic data generator to simulate enterprise data found in online retail businesses .
it combines structured data generation from the tpc - ds benchmark @xcite , semi - structured data on user clicks , and unstructured data from online product reviews .
queries cover data _ velocity _ by processing periodic refreshes that feed into the data store , _ variety _ by including free - text user reviews , and _ volume _ by querying over a large web log of clicks .
we take a similar approach for benchmarking fast data platforms , targeting the iot domain specifically and using real public data streams .
there has been some recent work on benchmarking iot applications .
in particular , the generating large volumes of synthetic sensor data with realistic values is challenging , yet required for benchmarking . _
iotabench _
@xcite provides a scalable synthetic generator of time - series datasets .
it uses a markov chain model for scaling the time series with a limited number of inputs such that important statistical properties of the stream is retained in the generated data .
they have demonstrated this for smart meter data .
the benchmark also includes six sql queries to evaluate the performance of different query platforms on the generated dataset .
their emphasis is more on the data characteristics and content , which supplements our focus on the systems aspects of the executing platform .
citybench @xcite is a benchmark to evaluate rdf stream processing systems .
they include different generation patterns for smart city data , such as traffic vehicles , parking , weather , pollution , cultural and library events , with changing event rates and playback speeds .
they propose fixed set of semantic queries over this dataset , with concurrent execution of queries and sensor streams . here , the target platform is different ( rdf database ) , but in a spirit as our work .
in this section , we review the common application composition capabilities of dsps , and the dimensions of the streaming applications that affect their performance on dsps .
these semantics help define and describe streaming iot applications based on dsps capabilities . subsequently in this section , we also categorize iot tasks , applications and data streams based on the domain requirements . together , these offer a search space for defining workloads that meaningfully and comprehensively validate iot applications on dsps .
dsps applications are commonly composed as a _ dataflow graph _ , where vertices are user provided _ tasks _ and directed edges are refer to _ streams of messages _ that can pass between them . the graph need not be acyclic .
tasks in the dataflows can execute zero or more times , and a task execution usually depends on data - dependency semantics , i.e , when `` adequate '' inputs are available , the task executes . however , there are also more nuanced patterns that are supported by dsps that we discuss
. _ messages _ ( or events or tuples ) from / to the stream are consumed / produced by the tasks .
dsps typically treat the messages as opaque content , and only the user logic may interpret the message content .
however , dsps may assign identifiers to messages for fault - tolerance and delivery guarantees , and some message attributes may be explicitly exposed as part of the application composition for the dsps to route messages to downstream tasks .
_ selectivity ratio _ , also called _ gain _ , is the number of output messages emitted by a task on consuming a unit input message , expressed as @xmath1=_input rate_:_output rate_. based on this , one can assess whether a task amplifies or attenuates the incoming message rate .
it is important to consider this while designing benchmarks as it can have a multiplicative impact on downstream tasks .
there are message generation , consumption and routing semantics associated with tasks and their dataflow composition .
[ fig : semantics ] captures the basic _ composition patterns _ supported by modern dsps .
` source ` tasks have only outgoing edge(s ) , and these tasks encapsulate user logic to generate or receive the input messages that are passed to the dataflow . likewise , ` sink ` tasks have only incoming edge(s ) and these tasks react to the output messages from the application , say , by storing it or sending an external notification . `
transform ` tasks , sometimes called _ map _ tasks , generate one output message for every input message received ( @xmath2 ) .
their user logic performs a transformation on the message , such as changing the units or projecting only a subset of attribute values . `
filter ` tasks allow only a subset of messages that they receive to pass through , optionally performing a transformation on them ( @xmath3 , @xmath4 ) .
conversely , a ` flatmap ` consumes one message and emits multiple messages ( @xmath5 ) .
an ` aggregate ` pattern consumes a _ window _ of messages , with the window width provided as a _ count _ or a _ time _ duration , and generates one or more messages that is an aggregation over each message window ( @xmath6 ) . when a task has multiple outgoing edges , routing semantics on the dataflow control if an output message is _ duplicated _ onto all the edges , or just one downstream task is selected for delivery , either based on a _ round robin _ behavior or using a _ hash function _ on an attribute in the outgoing message to decide the target task .
similarly , multiple incoming streams arriving at a task may be _ merged _ into a single interleaved message stream for the task . or alternatively , the messages coming on each incoming stream may be conjugated , based on order of arrival or an attribute exposed in each message , to form a _ joined _ stream of messages
. there are additional dimensions of the streaming dataflow that can determine its performance on a dsps .
tasks may be _ data parallel _ , in which case , it may be allocated concurrent resources ( threads , cores ) to process messages in parallel by different instances the task .
this is typically possible for tasks that do not maintain state across multiple messages .
the _ number of tasks _ in the dataflow graph indicates the size of the streaming application .
tasks are mapped to computing resources , and depending of their degree of parallelism and resource usage , it determines the cores / vms required for executing the application .
the _ length of the dataflow _ is the latency of the critical ( i.e. , longest ) path through the dataflow graph , if the graph does not have cycles .
this gives an estimate of the expected latency for each message and also influences the number of network hops a message on the critical path has to take in the cluster .
we list a few characteristics of the input data streams that impact the runtime performance of streaming applications , and help classify iot message streams .
the _ input throughput _ in messages / sec is the cumulative frequency at which messages enter the source tasks of the dataflow .
input throughputs can vary by application domain , and are determined both by the number of streams of messages and their individual rates .
this combined with the dataflow selectivity will impact the load on the dataflow and the output throughput . _
throughput distribution _ captures the variation of input throughput over time . in real - world settings ,
the input data rate is usually not constant and dsps need to adapt to this .
there may be several common data rate distributions besides a _ uniform _ one
. there may be _ bursts _ of data coming from a single sensor , or a coordinated set of sensors . a _ saw - tooth _
behavior may be seen in the ramp - up/-down before / after specific events . _
normal _ distribution are seen with diurnal ( day vs. night ) stream sources , with _
bi - modal _ variations capturing peaks during the morning and evening periods of human activity .
lastly , the _ message size _ provides the average size of each message , in bytes .
often , the messages sizes remain constant for structured messages arriving from specific sensor or observation types , but may vary for free - text input streams or those that interleave messages of different types .
this size help assess the communication cost of transferring messages in the dataflow .
iot covers a broad swathe of domains , many of which are rapidly developing .
so , it is not possible to comprehensively capture all possible iot application scenarios .
however , dsps have clear value in supporting the real - time processing , analytics , decision making and feedback that is intrinsic to most iot domains . here , we attempt to categorize these common processing and analytics tasks that are performed over real - time data streams
. * parse .
* messages are encoded on the wire in a standard text - based or binary representation by the stream sources , and need to be parsed upon arrival at the application .
text formats in particular require string parsing by the tasks , and are also larger in size on the wire .
the tasks within the application may themselves retain the incoming format in their streams , or switch to another format or data model , say , by projecting a subset of the fields .
industry - standard formats that are popular for iot domains include csv , xml and json text formats , and exi and cbor binary formats . *
* messages may require to be filtered based on specific attribute values present in them , as part of data quality checks , to route a subset of message types to a part of the dataflow graph , or as part of their application logic .
value and band - pass filters that test an attribute s _ numerical value ranges _ are common , and are both compact to model and fast to execute .
since iot event rates may be high , more efficient bloom filters may also be used to process _ discrete values _ with low space complexity but with a small fraction of false positives .
* statistical analytics . *
groups of messages within a sequential time or count window of a stream may require to be aggregated as part of the application .
the aggregation function may be _ common mathematical operations _ like average , count , minimum and maximum .
they may also be _ higher order statistics _
such finding outliers , quartiles , second and third order moments , and counts of distinct elements .
data cleaning _ like linear interpolation or denoising using kalman filters are common for sensor - based data streams .
some tasks may maintain just local state for the window width ( e.g. , local average ) while others may maintain state across windows ( e.g. , moving average )
. when the state size grows , here again approximate aggregation algorithms may be used .
* predictive analytics . * predicting future behavior of the system based on past and current messages is an important part of iot applications .
various statistical and machine - learning algorithms may be employed for predictive analytics over sensor streams .
the _ predictions _ may either use a recent window of messages to estimate the future values over a time or count horizon in future , or train models over streaming messages that are periodically used for predictions over the incoming messages .
the _ training _ itself can be an online task that is part of an application . for e.g. , arima and linear regression use statistical methods to predict uni- or multi - variate attribute values , respectively .
classification algorithms like decision trees , neural networks and nave bayes can be trained to map discrete values to a category , which may lead to specific actions taken on the system .
external libraries like weka or statistical packages like r may be used by such tasks .
* pattern detection . *
another class of tasks are those that identify patterns of behavior over several events .
unlike window aggregation which operate over static window sizes and perform a function over the values , pattern detection matches user - defined predicates on messages that may not be sequential or even span streams , and returned the matched messages .
these are often modeled as _ state transition automata _ or _ query graphs_. common patterns include contiguous or non - contiguous sequence of messages with specific property on each message ( e.g. , high - low - high pattern over 3 messages ) , or a join over two streams based on a common attribute value .
complex event processing ( cep ) engines @xcite may be embedded within the dsps task to match these patterns .
* visual analytics .
* other than automated decision making , iot applications often generate _ charts and animations _ for consumption by end - users or system managers .
these visual analytics may be performed either at the client , in which case the processed data stream is aggregated and provided to the users .
alternatively , the streaming application may itself periodically generate such plots and visualizations as part of the dataflow , to be hosted on the web or pushed to the client .
charting and visualization libraries like d3.js or jfreechart may be used for this purpose .
* io operations . *
lastly , the iot dataflow may need to access external storage or messaging services to access / push data into / out of the application .
these may be to store or load trained models , archive incoming data streams , access historic data for aggregation and comparison , and subscribe to message streams or publish actions back to the system .
these require access to _ file storage , sql and nosql databases , and publish - subscribe messaging systems_. often , these may be hosted as part of the cloud platforms themselves .
the tasks from the above categories , along with other domain - specific tasks , are composed together to form streaming iot dataflows .
these domain dataflows themselves fall into specific classes based on common use - case scenarios , and loosely map to the observe - orient - decide - act ( ooda ) phases .
_ extract - transform - load ( etl ) and archival _ applications are front - line `` observation '' dataflows that receive and pre - process the data streams , and if necessary , archive a copy of the data offline .
pre - processing may perform data format transformations , normalize the units of observations , data quality checks to remove invalid data , interpolate missing data items , and temporally reorder messages arriving from different streams .
the pre - processed data may be archived to table storage , and passed onto subsequent dataflow for further analysis .
_ summarization and visualization _
applications perform statistical aggregation and analytics over the data streams to understand the behavior of the iot system at a coarser granularity . such summarization can give the high - level pulse of the system , and help `` orient '' the decision making to the current situation .
these tasks are often succeeded by visualizations tasks in the dataflow to present it to end - users and decision makers .
_ prediction and pattern detection _ applications help determine the future state of the iot system and `` decide '' if any reaction is required .
they identify patterns of interest that may indicate the need for a correction , or trends based on current behavior that require preemptive actions .
for e.g. , a trend that indicates an unsustainably growing load on a smart power grid may decide to preemptively shed load , or a detection that the heart - rate from a fitness watch is dangerously high may trigger a slowdown in physical activities .
_ classification and notification _ applications determine specific `` actions '' that are required and communicate them to the iot system .
decisions may be mapped to specific actions , and the entities in the iot system that can enact those be notified . for e.g. , the need for load shedding in the power grid may map to specific residents to request the curtailment from , or the need to reduce physical activities may lead to a treadmill being notified to reduce the speed .
iot data streams are often generated by physical sensors that observe physical systems or the environment . as a result
, they are typically time - series data that are generated periodically by the sensors . the sampling rate for these sensors may vary from once a day to hundreds per second , depending on the domain .
the number of sensors themselves may vary from a few hundred to millions as well .
iot applications like smart power grids can generate high frequency plug load data at thousands of messages / sec from a small cluster of residents , or low frequency data from a large set of sensors , such as in smart transportation or environmental sensing . as a result
, we may encounter a wide range of input throughputs from @xmath7 to @xmath8 messages / sec . in comparison ,
streaming web applications like twitter deal with @xmath9 tweets / sec from 300 m users .
at the same time , this event rate itself may not be uniform across time .
sensors may also be configured to emit data only when there is a change in observed value , rather than unnecessarily transmitting data that has not changed .
this helps conserve network bandwidth and power for constrained devices when the observations are slow changing .
further , if data freshness is not critical to the application , they may sample at high rate but transmit at low rates but in a burst mode .
e.g. smart meters may collecting kwh data at 15 min intervals from millions of residents but report it to the utility only a few times a day , while the fitbit smart watch syncs with the cloud every few minutes or hours even as data is recorded every few seconds .
message variability also comes into play when human - related activity is being tracked .
diurnal or bimodal event rates are seen with single peaks in the afternoons , or dual peaks in the morning and evening .
e.g. , sensors at businesses may match the former while traffic flow sensors may match the latter .
there may also be a variety of observation types from the same sensor device , or different sensor devices generating messages .
these may appear in the same message as different fields , or as different data streams .
this will affect both the message rate and the message size .
these sensors usually send well - formed messages rather than free - text messages , using standards like senml .
hence their sizes are likely to be deterministic if the encoding format is not considered
text formats tend to bloat the size and also introduce size variability when mapping numbers to strings .
however , social media like tweets and crowd - sourced data are occasionally used by iot applications , and these may have more variability in message sizes .
we identify and formalize commonly - used quantitative performance measures for evaluating dsps for the iot workloads . *
latency . *
latency for a message that is generated by task is the time in seconds it took for that task to process one or more inputs to generate that message . if @xmath3 is the selectivity for a task @xmath10 , the time @xmath11 it took to consume @xmath12 messages to _ causally produce _
those @xmath13 output messages is the latency of the @xmath13 messages , with the _ average latency _ per message given by @xmath14 . when we consider the average latency @xmath15 of the dataflow application , it is the average of the time difference between each message consumed at the source tasks and all its causally dependent messages generated at the sink tasks .
the latency per message may vary depending on the input rate , resources allocated to the task , and the type of message being processed . while this task latency is the inverse of the mean throughput , the _ end - to - end latency _ for the task within a dataflow will also include the network and queuing time to receive a tuple and transmit it downstream .
* throughput . *
the output throughput is the aggregated rate of output messages emitted out of the sink tasks , measured in messages per second .
the throughput of a dataflow depends on the input throughput and the selectivity of the dataflow , provided the resource allocation and performance of the dsps are adequate . ideally , the output throughput @xmath16 , where @xmath17 is the input throughput for a dataflow with selectivity @xmath1 .
it is also useful to measure the _ peak throughput _ that can be supported by a given application , which is the maximum stable rate that can be processed using a fixed quanta of resources .
both throughput and latency measurements are relevant only under
_ stable conditions _ when the dsps can sustain a given input rate , i.e. , when the latency per message and queue size on the input buffer remain constant and do not increase unsustainably .
* the ideal output throughput may deviate due to variable rate of the input streams , change in the paths taken by the input stream through the dataflow ( e.g. , at a ` hash ` pattern ) , or performance variability of the dsps .
we use jitter to track the variation in the output throughput from the expected output throughput , defined for a time interval @xmath18 as , @xmath19 where the numerator is the observed difference between the expected and actual output rate during interval @xmath18 , and the denominator is the expected long term average output rate given a long - term average input rate @xmath20 . in an ideal case , jitter will tend towards zero . *
cpu and memory utilization .
* streaming iot dataflows are expected to be resource intensive , and the ability of the dsps to use the distributed resources efficiently with minimal overhead is important .
this also affects the vm resources and consequent price to be paid to run the application using the given stream processing platform .
we track the cpu and memory utilization for the dataflow as the average of the cpu and memory utilization across all the vms that are being used by the dataflow s tasks .
the per - vm information can also help identify which vms hosting which tasks are the potential bottlenecks , and can benefit from data - parallel scale - out .
we propose benchmark workloads to help evaluate the metrics discussed before for various dsps .
these benchmarks are in particular targeted for emerging iot applications , to help them distinguish the capabilities of contemporary dsps on cloud computing infrastructure .
the benchmarks themselves have two parts , the dataflow logic that is executed on the dsps and the input data streams that they are executed for .
we next discuss our choices for both .
we have identified two real - world iot data streams available in the public domain as candidates for our benchmarking workload .
these correspond to smart cities domain , which a fast - growing space within iot .
their features are shown in table [ tbl : datasets ] and event rate distribution in fig .
[ fig : data - distribution ] .
.smart cities data stream features and rates at @xmath21 scaling [ cols="^,^,^,^,^,^,^",options="header " , ] [ tbl : tasts ] we include a single xml parser as a representative parsing operation within our suite .
the bloom filter is a more practical filter operation for large discrete datasets , and we prefer that to a simple value range filter .
we have several statistical analytics and aggregation tasks .
these span simple averaging over a single attribute value to and second order moments over time - series values , to kalman filter for denoising of sensor data and approximate count of distinct values for large discrete attribute values .
predictive analytics using a multi - variate linear regression model that is trained offline and a sliding window univariate model that is trained online are included
. a decision tree machine learning for discrete attribute values is also used for classification , based on offline training .
lastly , we have several io tasks for reading and writing to cloud file and nosql storage , and to publish to an mqtt publish - subscribe broker for notifications . due to limited space , we skip pattern matching and visual analytics task categories . a micro - benchmark dataflow is composed for each of these tasks as a sequence of a source task , the benchmark task and a sink task .
as can be seen , these tasks also capture different dataflow patterns such as transform , filter , aggregate , flat map , source and sink .
application benchmarks are valuable in understanding how non - trivial and meaningful iot applications behave on dsps .
application dataflows for a domain are most representative when they are constructed based on real or realistic application logic , rather than synthetic tasks . in case applications use highly - custom logic or proprietary libraries , this may not be feasible or reusable as a community benchmark .
however , many of the common iot tasks we have proposed earlier are naturally composable into application benchmarks that satisfy the requirements of a ooda decision making loop .
we propose application benchmarks that capture two common iot scenarios : a _ data pre - processing and statistical summarization ( stats ) _ application and a _ predictive analytics ( pred ) _ application
. stats ( fig .
[ fig : app - stats ] ) ingests incoming data streams , performs data filtering of outliers on individual observation types using a bloom filter , and then does three concurrent types of statistical analytics on observations from individual sensor / taxi ids : sliding average over a @xmath22 event window for city / taxi ( @xmath23 mins native time window ) , kalman filter for smoothing followed by a sliding window linear regression , and an approximate count of distinct readings .
the outcomes from these statistics are published by an mqtt task , which can separately be subscribed to and visualized on a client browser or a mobile app .
the dummy sink task is used for logging .
+ the pred dataflow captures the lifecycle of online prediction and classification to drive visualization and decision making for iot applications .
it parses incoming messages and forks it to a decision tree classifier and a multi - variate regression task .
the decision tree uses a trained model to classify messages into classes , such as good , average or poor air quality , based on one or more of their attribute values .
the linear regression uses a trained model to predict an attribute value in the message using several others .
it then estimates the error @xmath24 between the predicted and observed value , normalized by the sliding average of the observations .
these outputs are then grouped and plotted , and the output file written to cloud storage for hosting on a portal .
one realistic addition is the use of a separate stream to periodically download newly trained classification and regression models from cloud storage , and push them to the prediction tasks . as such , these applications leverage many of the compositional capabilities of dsps .
the dataflows include _ single and dual sources _ , tasks that are _ composed sequentially and in parallel _ , _ stateful and stateless _ tasks , and _ data parallel tasks _ allowing for concurrent instances .
each message in the city and taxi streams contains multiple observation fields , but several of these tasks are applicable only on univariate streams and some are meaningful only from time - series data from individual sources .
thus , the initial parse task for stats uses a _
flat map _ pattern ( @xmath5 ) to create observation - specific streams early on .
these streams are further passed to task instances , grouped by their observation type and optionally their sensor i d using a _ hash pattern_.
we implement the 13 micro - benchmarks as generic java tasks that can consume and produce objects .
these tasks are building blocks that can be composed into micro - dataflows and the stats and pred dataflows using any dsps that is being benchmarked . to validate our proposed benchmark , we compose these dataflows on the apache storm open source dsps , popular for fast - data processing , using its java apis .
we then run these for the two stream workloads and evaluate them based on the metrics we have defined .
the benchmark is available online at ` https://github.com/dream-lab/bm-iot ` . in storm ,
each task logic is wrapped by a _ bolt _ that invokes the task for each incoming tuple and emits zero or more response tuples downstream .
the dataflow is composed as a _
topology _ that defines the edges between the bolts , and the _ groupings _ which determine duplicate or hash semantics .
we have implemented a scalable data - parallel event generator that acts as a source task ( _ spout _ ) .
it loads time - series tuples from a given csv file and replays them as an input stream to the dataflow at a constant rate , at the maximum possible rate , or at intervals determined by the timestamps , optionally scaled to go faster or slower .
we generate random integers as tuples at maximum rate for the micro - benchmarks , and replay the original city and taxi datasets at @xmath21 their native rates for the application benchmarks , following the earlier distribution .
we use apache storm @xmath25 running on openjdk 1.7 , and hosted on _ centos _ virtual machines ( vms ) in the singapore data center of microsoft azure public cloud . for the micro - benchmarks , storm runs the task being benchmarked on one exclusive ` d1 ` size vm ( @xmath26 intel xeon e5 - 2660 core at 2.2 ghz , @xmath27 gib ram , @xmath28 gib ssd ) , while the supporting source and sink tasks and the master service run on a ` d8 ` size vm ( @xmath29 intel xeon e5 - 2660 core at 2.2 ghz cores , @xmath30 gib ram , @xmath31 gib ssd ) .
the larger vm for the supporting tasks and services ensures that they are not the bottleneck , and helps benchmark the peak rate supported by the micro - benchmark task on a single core vm . for the stats and pred application benchmark
, we use ` d8 ` vms for all the tasks of the dataflow , while reserving additional ` d8 ` vms to exclusively run the spout and sink tasks , and master service .
we determine the number of cores and data parallelism required by each task based on the peak rate supported by the task on a single core as given by the micro - benchmarks , and the peak rate seen by that task for a given dataflow application and stream workload . in some cases that are i / o bound ( e.g. , mqtt , azure storage ) rather than cpu bound
, we run multiple task instances on a single core .
we log the i d and timestamp for each message at the source and the sink tasks in - memory to calculate the latency , throughput and jitter metrics , after correcting for skews in timestamps across vms .
we also sample the cpu and memory usage on all vms every 5 secs to plot the utilization metrics .
each experiment runs for @xmath32 mins of wallclock time that translates to about @xmath33 days of event data for the city and taxi datasets at @xmath21 scaling ] .
[ fig : storm : micro : bm ] shows plots of the different metrics evaluated for the micro - benchmark tasks on storm when running at their peak input rate supported on a single ` d1 ` vm with one thread .
the _ peak sustained throughput _ per task is shown in fig .
[ fig : storm : micro : peakthru ] in _ log - scale_. we see that most tasks can support @xmath34 msg / sec or higher rate , going up to @xmath35 msg / sec for blf , kal and dac .
xml parsing is highly cpu bound and has a peak throughput of only @xmath36 msg / sec , and the azure operations are i / o bound on the cloud service and even slower .
the inverse of the peak sustained throughput gives the _
mean latency_. however , it is interesting to examine the _ end - to - end latency _ , calculated as the time taken between emitting a message from the source , having it pass through the benchmarked task , and arrive at the sink task .
this is the effective time contributed to the total tuple latency by this task running within storm , including framework overheads .
we see that while the mean latencies should be in sub - milliseconds for the observed throughputs , the box plot for end - to - end latency ( fig .
[ fig : storm : micro : latency ] ) varies widely up to @xmath37 ms for q3 .
this wide variability could be because of non - uniform task execution times due to which slow executions queue up incoming tuples that suffer higher queuing time , such as for dtc and mlr that both use the weka library . or tasks supporting a high input rate in the order of @xmath38 msg / sec , such as dac and kal , may be more sensitive to even small per - tuple overhead of the framework , say , caused by thread contention between the storm system and worker threads , or queue synchronization .
the azure tasks that have a lower throughput also have a higher end - to - end latency , but much of which is attributable directly to the task latency .
+ the box - plot for _ jitter _ ( fig .
[ fig : storm : micro : jitter ] ) shows values close to zero in all cases .
this indicates the long - term stability of storm in processing the tasks at peak rate , without unsustainable queuing of input messages .
the wider whiskers indicate the occasional mismatch between the expected and observed output rates .
the box plots for cpu utilization ( fig .
[ fig : storm : micro : cpu ] ) shows the single - core vm effectively used at @xmath39 or above in all cases except for the azure tasks that are i / o bound . the memory utilization ( fig .
[ fig : storm : micro : mem ] ) appears to be higher for tasks that support a high throughput , potentially indicating the memory consumed by messages waiting in queue rather than consumed by the task logic itself .
+ the stats and pred application benchmarks are run for the city and taxi workloads at @xmath21 their native rates , and the performance plots shown in fig .
[ fig : apps ] .
the end - to - end latencies of the applications depend on the sum of the end - to - end latencies of each task in the critical path of the dataflow .
the peak rates supported by the tasks in stats is much higher than the input rates of city and taxi .
so the latency box plot for stats is tightly bound ( fig .
[ fig : storm : stats : latency ] ) and its median much lower at @xmath40 ms compared to the end - to - end latency of the tasks at their peak rates .
the jitter is also close to zero in all cases .
so storm can comfortably support stats for city and taxi on 7 and 5 vms , respectively .
the distribution of vm cpu utilization is also modest for stats .
city has a @xmath41 median with a narrow box ( fig .
[ fig : storm : stats : city : cpu ] ) , while taxi has a low @xmath42 median with a wide box ( fig .
[ fig : storm : stats : taxi : cpu ] ) this is due to its bi - modal distribution with low input rates at nights , with lower utilization , and high in the day with higher utilization . for the pred application , we see that the latency box plot is much wider , and the median end - to - end latency is between @xmath43 ms for city and taxi ( fig .
[ fig : storm : pred : latency ] ) .
this reflects the variability in task execution times for the weka tasks , dtc and mlr , which was observed in the micro - benchmarks too .
the azure blob upload also adds to the absolute increase in the end - to - end time .
the jitter however remains close to zero , indicating sustainable performance .
the cpu utilization is also higher for pred , reflecting the more complex task logic present in this application relative to stats .
in this paper , we have proposed a novel application benchmark for evaluating distributed stream processing systems ( dsps ) for the internet of things ( iot ) domain .
fast data platforms like dsps are integral for the rapid decision making needs of iot applications , and our proposed workload helps evaluate their efficacy using common tasks found in iot applications , as well as fully - functional applications for statistical summarization and predictive analytics .
these are combined with two real - world data streams from smart transportation and urban monitoring domains of iot .
the proposed benchmark has been validated for the highly - popular apache storm dsps , and the performance metrics presented . as future work , we propose to add further depth to some of the iot task categories such as parsing and analytics , and also add two further applications on archiving real - time data and detecting online patterns .
we also plan to include more data stream workloads having different temporal distributions and from other iot domains , with a possible generalization of the distributions to allow for synthetic data generation .
the benchmark can also be used to evaluate other popular dsps such as apache spark streaming .
we acknowledge detailed inputs provided by tarun sharma of nvidia corp . and formerly from iisc in preparing this paper .
the experiments on microsoft azure were supported through a grant from azure for research . | internet of things ( iot ) is a technology paradigm where millions of sensors monitor , and help inform or manage , physical , environmental and human systems in real - time .
the inherent closed - loop responsiveness and decision making of iot applications makes them ideal candidates for using low latency and scalable stream processing platforms .
distributed stream processing systems ( dsps ) are becoming essential components of any iot stack , but the efficacy and performance of contemporary dsps have not been rigorously studied for iot data streams and applications . here , we develop a benchmark suite and performance metrics to evaluate dsps for streaming iot applications .
the benchmark includes @xmath0 common iot tasks classified across various functional categories and forming micro - benchmarks , and two iot applications for statistical summarization and predictive analytics that leverage various dataflow compositional features of dsps .
these are coupled with stream workloads sourced from real iot observations from smart cities .
we validate the iot benchmark for the popular apache storm dsps , and present empirical results . |
since the discovery of the prototypical `` hot jupiter '' orbiting the star 51 pegasi in 1995 , more than 450 extrasolar planets have been identified .
this flurry of discovery has been driven largely by technological innovation and the development of new observational techniques .
precise doppler measurements have played a particularly important role in the discovery of extrasolar planets .
the search for unseen orbiting companions to stars by measuring the subtle doppler shifts of stellar spectral lines is more than a century old ( e.g. @xcite ) , and since the late 1800s the precision of these measurements has improved by more than four orders of magnitude . since the amplitude of the doppler signal induced by an unseen companion is directly proportional to the companion s mass ,
the discovery of extrasolar planets is a direct result of steady improvements to measurement techniques that have been used for over a century to study binary star systems .
approximately @xmath9 of the known extrasolar planetary systems have low - mass star hosts ( m0-m4 ; www.exoplanet.eu ) .
the bias in doppler surveys toward stars more massive than m dwarfs is due largely to the technical limitations of obtaining precise measurements of cool , intrinsically faint objects .
understanding the rate of occurrence of planets orbiting these lowest mass stars and brown dwarfs , collectively referred to as ultracool dwarfs ( ucds , spectral types later than m5 ) , may have important implications for theories of planet formation since the core accretion and disk instability formation scenarios make different predictions about the occurrence of planetary companions as a function of host mass @xcite .
while it has been shown that early m dwarfs have a relative paucity of close in jupiter - mass planets @xcite , we are just now beginning to understand the occurrence of super - earth ( @xmath10 ) planets to mid - m stars or any type of planet orbiting late - m or l dwarfs .
doppler planet surveys generally include no ucd targets @xcite , so little is known about the rate at which planetary companions accompany the lowest mass stars and brown dwarfs .
there are some initial indications from microlensing surveys that sub - jupiter - mass companions orbiting at several au from m dwarfs may be common @xcite , but these findings are not yet statistically robust .
several examples of possible planetary companions to brown dwarfs do exist , including a @xmath11 companion found orbiting a young brown dwarf in a doppler survey conducted by @xcite , a giant planetary companion to 2m1207@xmath339 found by @xcite in a direct imaging survey , and a possible super - earth orbiting the ucd moa-2007-blg-192 detected via microlensing @xcite .
there is strong observational evidence for the initial stages of planet formation around young ucds in the form of a high disk fraction @xcite and the formation of silicate grains @xcite .
the formation of planets around ucds with @xmath12 has been modeled by @xcite who found that , depending on the mass of the protoplanetary disk , super - earths up to @xmath13 may be relatively common ( @xmath14 of ucds ) if disk mass scales linearly with host mass .
the interaction of a planet with a gaseous disk leads to gravitational torques that can cause a planet to lose angular momentum and migrate within the disk .
for small planets ( @xmath15 ) , the disk - planet interactions are linear , resulting in a type i migration that can cause very rapid inward movement .
more massive planets may be able to open a gap in the protoplanetary disk and then torques between the planet and the inner and outer edges of the gap may cause the planet to slowly migrate inward through type ii migration .
ucd planets may be found at relatively large separations ( @xmath16 au ) since inward migration to short orbital periods through type ii migration is not expected to be efficient in ucd protoplanetary disks .
the detection of a significant population of close - in companions to ucds would place interesting constraints on planetary migration via the type i mechanism since the rapid inward movements due to this mechanism are expected to cause protoplanets to fall into the star on short timescales .
@xcite predict that the formation of giant planetary companions to ucds should be completely inhibited and propose that systems like 2m1207@xmath339 form in a manner similar to that of binary stars .
doppler planet searches are very sensitive to spectroscopic binary systems .
binary star systems afford one of the few opportunities to directly measure the masses and radii of stars and measurements of stars in binary systems are an important component of the observational basis of our theoretical models of stellar structure and evolution .
the are four different types of spectroscopic binary systems : single - lined ( sb1 ) , double - lined ( sb2 ) , single - lined eclipsing ( seb ) , and double - lined eclipsing ( deb ) . in an sb1 binary
the reflex motion of the primary ( more luminous and usually more massive ) star is observed and when combined with the orbital period and eccentricity can be used to define a mass function , a transcendental equation involving the masses of both components and the inclination .
the inclination of the system is not known , so additional observations , such as measurements of the astrometric orbit , are required to determine the actual masses of both components . in an sb2 system the spectral lines of
both the primary and secondary are observed and the ratio of the radial velocity semi - amplitudes of the components directly determines the ratio of their masses ( @xmath17 ) . using a technique like todcor @xcite to analyze observations of an sb2 system it may also be possible to simultaneously determine mass and flux ratios of the components of the system , enabling direct tests of theoretical models of coeval low - mass stars and brown dwarfs . as with an sb1 system , the system inclination is not known in an sb2 , so individual masses can not be directly measured . in an seb system light from the secondary is not detected , but its presence is inferred from both the reflex motion of the primary and the diminution in brightness that occurs as the secondary eclipses the primary . in these systems ,
of which the transiting extrasolar planets are a specific case , the orbital inclination is constrained by the fact that an eclipse occurs .
the deb is a rare , but very important , type of binary that allows for precise measurements of the masses and radii of both components of the binary .
very few ucd spectroscopic binaries are known , meaning that theoretical models of low - mass stars and brown dwarfs are relatively untested compared to models of sun - like stars .
in fact , there are significant ( @xmath18 ) discrepancies between models and mass and radius measurements of low - mass stars in eclipsing binary systems @xcite . for ucds , only one deb system is known @xcite , serving as the lone observational benchmark for models of young brown dwarfs . in this young ( @xmath19 gyr ) system ,
the measured radii are consistent with theoretical models but the estimated temperatures indicate that the less massive component is actually hotter , contrary to theoretical predictions for coeval brown dwarfs . since ucds that appear brightest in the sky are necessarily close to the sun ,
direct imaging surveys have been very successful in detecting ucd binaries with orbital separations @xmath16 au . the orbital motions in these long - period visual binary systems can be observed ( e.g. @xcite , @xcite , @xcite , @xcite ) , providing another opportunity to measure masses of ucds .
discovering additional ucd binaries , particularly sb2 and deb systems , is crucial for improving our understanding of stellar astrophysics at and below the bottom of the main sequence .
observations of a large sample of binary systems also enable tests of models of the formation history of ucds .
the process through which ucds form is not well understood , and the statistical properties of the orbital separations and mass ratios of binary systems help to test potential formation scenarios .
for example , some models of ucd formation suggest that these objects undergo ejection from star formation regions before they have the opportunity to accrete enough mass to become main - sequence stars ( @xcite , @xcite ) .
if this is the case , wide binaries ( @xmath20 au ) with low binding energies are expected to be rare .
thanks to direct imaging surveys , the binary fraction at large separations has been well studied .
compared to sun - like stars , ucd binaries tend to have larger mass ratios ( @xmath21 ) and smaller separations ( @xmath22 au ) and very few wide ( @xmath20 au ) systems are seen .
most systems with small ( @xmath6 au ) separations are not resolved by imaging surveys , but their relatively short periods ( years instead of decades ) make them prime targets for doppler surveys . since no comprehensive doppler survey of ucds has been carried out , our understanding of the overall distribution of system properties is incomplete at small separations @xcite . obtaining precise doppler measurements poses a significant technical challenge , particularly if the target is a ucd . in the 1970s astronomers realized that having a simultaneous wavelength calibrator that superimposes absorption features of known wavelengths onto a source spectrum provides a major advantage in terms of doppler precision for slit spectrographs @xcite . prior to the advent of the gas cell technique
( hf by @xcite and later i@xmath23 ) , atomic and molecular absorption features in the earth s atmosphere were used for this purpose . while not inherently stable like the gas in an absorption cell , telluric lines have been used to produce doppler measurements with a month - to - month precision of 5 - 20 m s@xmath1 @xcite . after making corrections based on a simple model of atmospheric winds ,
@xcite have demonstrated that atmospheric o@xmath24 lines at optical wavelengths can be used to make rv measurements with a precision of 2 m s@xmath1 over timescales of years .
doppler measurements of sun - like stars with a precision exceeding 1 m s@xmath1 have been demonstrated using two different techniques for calibrating high - resolution spectroscopic data . for bright early - m dwarfs both the thorium - argon ( thar ) emission lamps and simultaneous iodine ( i@xmath23 ) absorption cells
have been used to obtain rv precision of 3 - 5 m s@xmath1 @xcite . due to their cool temperatures ( @xmath25k ) and small sizes ( @xmath26 ) , ucds
are intrinsically very faint at the wavelengths where these measurements are made ( 400 to 700 nm ) , limiting observations to only the few brightest targets on the sky .
making precise doppler measurements at near infrared ( nir ) wavelengths is a very attractive option for exploring the population of planets orbiting ucds . until quite recently ,
the precision of nir doppler measurements of ucds has tended to lag behind that of rv measurements of sun - like stars by two orders of magnitude .
this is due in part to the relative complexity and expense of nir echelle spectrographs , the relative faintness of cool dwarfs , and to the worse noise properties of nir detectors compared to ccds .
in addition , there has been a lack of suitable wavelength references in the nir .
the i@xmath23 cell is not effective at these wavelengths , but the th lines in thar emission lamps may prove useful in @xmath27 and @xmath28 bands . both @xcite and @xcite
provide a summary of future prospects for calibrating nir echelle spectra using gas absorption cells and emission line lamps .
the nir is replete with telluric absorption lines due to h@xmath23o and ch@xmath0 .
in this spectral region ucds have a rich set of molecular absorption features that can potentially be used to make precise doppler measurements .
we have developed a technique that relies on telluric ch@xmath0 absorption features as a simultaneous wavelength reference and exploits the rich set of co absorption features found in the spectra of ucds near 2.3@xmath29 m to make doppler measurements with a limiting precision of approximately 50 m s@xmath1 .
high - resolution nir spectrographs that could make use of this technique are expected to be an important component of the suites of instruments on future large telescopes and @xcite and @xcite report the development of new high - resolution instruments that should be able to achieve 10 m s@xmath1 precision at nir wavelengths .
doppler measurements with a precision of @xmath30 m s@xmath1 have been demonstrated by @xcite , @xcite , @xcite , @xcite , and @xcite , and a doppler precision in the range 5 - 20 m s@xmath1 has been demonstrated on short timescales using the crires instrument on vlt by @xcite , @xcite , and @xcite .
recently , @xcite used an nh@xmath31 absorption cell with crires to obtain rv measurements of bright ( @xmath32 ) mid - m dwarfs in k band with a precision approaching 5 m s@xmath1 .
we do not expect to reach this impressive level of precision for two reasons : first , the resolution of nirspec is r=25000 , which is significantly worse than that of crires ( r=100000 ) .
second , all but eight of the 59 targets in our survey have k magnitudes between 11 and 12.5 , significantly fainter than the faintest targets reported in @xcite or @xcite .
we report the results of a doppler survey of 59 ucds using the nirspec instrument on the keck ii telescope .
our observations span a period of six years and we demonstrate sensitivity to giant planetary companions as well as ucd - ucd binaries with small orbital separations . in section 2
we describe our ucd sample and our nirspec observations . in section 3
we describe the details of our reduction and calibration of the nirspec data . in section 4
we describe our nir doppler technique , the expected precision , and potential sources of noise that limit the overall precision we achieve . in section 5
we discuss the overall statistical properties of our doppler measurements .
in section 6 we describe four individual rv variables and present orbital solutions . in section 7
we describe the rotational and kinematic properties of our sample and compare the distributions of these values to those in the literature . in section 8
we estimate the rate of tight ( @xmath6au ) ucd binaries and simulate the sensitivity of our survey to giant planet companions .
thanks to all - sky nir surveys such as 2mass , sdss , and denis , the l spectral class is a well - studied group of several hundred old low - mass stars and younger brown dwarfs . there is an inherent degeneracy between age and spectral type for these objects , but at field ages ( @xmath33 gyr ) the mid - l dwarfs are expected to be brown dwarfs , objects with masses below the minimum required for main sequence hydrogen burning , while late m and early l dwarfs may be very small hydrogen burning stars @xcite .
the brown dwarfs slowly cool , radiating away their initial thermal energy over billions of years . with their cool temperatures ,
the atmospheres of ucds contain a wide array of molecules , including tio , vo , and co , as well as dust particles , leading to complex nir spectra @xcite .
we selected a sample of field ucd dwarfs brighter than @xmath34 observable from mauna kea ( dec@xmath35 ) .
our targets and their observed properties are listed in table 1 .
the majority of our targets are classified as l dwarfs , though three may be classified as early - l or late - m depending on the spectral diagnostics used .
today , our sample contains more than @xmath36 of the known l dwarfs that satisfy our magnitude and declination limits ( www.dwarfarchives.org ) , though a number of new l dwarfs were discovered during the course of our survey . between march , 2003 and may , 2009 we collected approximately 600 individual observations of a sample of 59 ucds using the nirspec @xcite instrument on the keck ii telescope .
nirspec is a high - resolution , cross - dispersed nir echelle spectrograph and is a powerful instrument for high - resolution spectroscopy of cool stars and brown dwarfs .
while nirspec can be operated in conjunction with the ao system , our observations were obtained without ao since many of our targets are too faint for ao observations .
we selected the 3-pixel ( 0.432@xmath37 ) slit , the n7 order blocking filter , the thin ir blocker , and a spectrograph configuration designed to place our desired spectral region around the co bandhead ( 2.285 to 2.318 @xmath38 ) near the center of echelle order 33 .
this setup provided a resolution of r=25000 and the 3-pixel slit was a good match for the typical seeing in k - band at mauna kea .
over the course of our survey we utilized this same spectrograph set - up and by using emission line lamps we were able to adjust the echelle and cross disperser angles in order to reproduce the positions of the echelle orders to within @xmath39 nm .
nirspec employs a 1024x1024 pixel aladdin insb array with 27@xmath38 pixels and all of our science data were gathered using fowler sampling ( mcds-16 ) readouts in order to reduce the read noise to the nominal level of 25 e@xmath40 .
we gathered observations of our targets in nod pairs where the target was nodded along the slit by approximately 6@xmath37 between the first and second exposures of a pair .
this observing strategy facilitates the removal of sky emission lines through the subtraction of consecutive 2d images .
we selected integration times so as to achieve a s / n per pixel of between 50 and 100 in each of our individual extracted 1d spectra with exposure times ranging from 500 to 1200 seconds per nod position . on each night
we gathered an extensive set of calibration data including a large number of flat field images and observations of bright , rapidly rotating a stars at a range of airmasses .
the a star spectra are free from stellar absorption features in our spectral region and are therefore useful for monitoring changes in telluric absorption . during the course of our survey we obtained between two and 16 epochs of observations for each target in our sample .
this inhomogeneous pattern of visits was determined in part by the scheduling of our observing time , but objects were also prioritized based on their projected rotational velocity , @xmath4 .
typically , we observed objects with large @xmath4 , which limits our doppler precision , only twice , while objects exhibiting clear evidence for doppler variations were observed at every opportunity .
we reduced the nirspec data and extracted spectra from order 33 using a set of custom idl procedures developed for this survey to flat field the 2d spectra , trace the spectral orders , and extract 1d spectra . for each observing session , which we defined as the period between physical movements of the internal components of the spectrograph ,
sets of 20 flat field images were median combined to produce a `` superflat '' . as a result of computer or hardware problems , there were occasionally multiple observing sessions defined within a single observing night .
the individual flat fields have an integration time of 4s , resulting in an average signal of @xmath41 adu per pixel in order 33 .
the aladdin detector has a small dark current ( 0.2 e@xmath1 pixel@xmath1 s@xmath1 ) so we also gathered 4s dark frames for use in the creation of the superflats .
prior to median combination the individual flat fields were each normalized so as to compensate for changes in the overall flux levels due to warming of the flat field lamp .
we used the superflat to trace echelle order 33 and to define the position of the order across the detector .
since we replicated the same spectrograph configuration during each observing session , the positions of the echelle orders are known to within a few pixels _ a priori _ in all of our data .
we began the reduction and extraction procedures by subtracting nod pairs .
provided that changes in the detector or spectrograph properties were negligible over the timescale of the nod pair , this effectively removes the dark current and the bias level of the detector .
if the sky brightness is not rapidly changing then night sky emission lines are also removed by pair subtraction . following subtraction , the two resulting 2d difference images ( a - b and b - a ) were flat fielded using the superflat to compensate for sensitivity variations both across the order and at the pixel - to - pixel level , resulting in intensity rectified difference images .
we trimmed 24 noisy columns from one edge of the detector , leaving a total of 1,000 columns . in our description of the data the echelle orders run roughly parallel to the rows of the detector .
we extracted spectra from the intensity rectified difference images following the procedures outlined in @xcite .
the position of the spectrum across order 33 was determined by fitting a gaussian in the spatial direction at each column and then fitting the resulting centers to a fourth - order polynomial with outlier rejection . using the difference image
, we built an empirical model of the spectral profile within order 33 in the spatial direction .
this model accommodates smooth variations in the width or shape of the profile across the order and is normalized so that the integral of the spectral profile at each column is unity . at each column
we fit this model spectral profile to the data by solving for the scale factor and an additive offset , to account for incomplete sky subtraction , that best fits the data in a least squares sense .
the variance for each pixel was determined from the quoted gain and read noise estimated from a region of the nirspec detector between the spectral orders .
we found that the read noise estimated in this way was often close to 75 e@xmath40 , much larger than the quoted value of 25 e@xmath40 .
the optimal estimate of the total flux at each of the 1,000 columns was determined by the scale factor of the best - fit model spectral profile .
each profile fit was conducted iteratively to mitigate the effects of cosmic rays or bad pixels by rejecting outliers and then re - fitting .
some of our nirspec data exhibit a significant additional noise .
a transient pattern is sometimes seen in a single quadrant of the nirspec detector such that every eighth row has significantly enhanced noise .
the phase of this pattern changes in time both within a night and between nights while the eight pixel periodicity remains fixed .
these noisy rows run roughly parallel to the echelle orders so , depending on the phase of the pattern , they can have a significant impact on the s / n of the extracted data .
the enhanced noise was seen in approximately 22@xmath42 of our observations , though not always in the immediate vicinity of order 33 . in a smaller subset of our data
more complex noise patterns were seen with multiple patterns each having an eight pixel period .
we visually inspected all of the individual extracted spectra and culled approximately @xmath14 as having poor s / n or severe noise problems due to order 33 falling along a particularly noisy row .
we forward modeled the extracted spectra to measure the stellar radial velocity ( rv ) and projected rotational velocity ( @xmath4 ) .
this procedure followed the methods described in @xcite and is similar to that used by @xcite to obtain 3 m s@xmath1 doppler precision at optical wavelengths using an i@xmath43 absorption cell .
our simultaneous calibrator is ch@xmath0 located not in a cell but in earth s atmosphere .
the basis for our modeling procedure is the interpolation and convolution of high - resolution spectral models to fit the lower resolution nirspec data , which we denote @xmath44 , by minimizing @xmath45 .
the basic form of our model can be expressed @xmath46 \times t(\lambda)\right ) \star lsf\ ] ] where @xmath47 indicates convolution , @xmath48 is a high resolution ucd template , @xmath49 is the rotational broadening kernel , @xmath50 is the telluric spectrum , and @xmath51 is the spectrograph line spread function .
we began with a library of high - resolution synthetic template spectra computed as described in @xcite and @xcite .
the models apply the condensation cloud model of @xcite with a sedimentation parameter of @xmath52 , corresponding to a moderate amount of condensate settling .
the models used here have solar metallicity @xcite , use the opacities described in @xcite , a fixed gravity of @xmath53 ( cgs ) , and cover a range of @xmath54 from 1200 to 2400@xmath55k .
the synthetic spectra provide monochromatic fluxes spaced @xmath56 m apart .
we incorporated line broadening due to stellar rotation by convolving with the kernel defined by @xcite using a linear limb - darkening parameter of 0.6 as appropriate for cool stars at infrared wavelengths @xcite .
we also used a high - resolution ( @xmath57 m spacing ) telluric spectrum derived from observations of the sun provided by @xcite . using quadratic interpolation we placed the synthetic ucd template and telluric model onto an evenly spaced wavelength grid with @xmath58 m spacing , about five times finer than the nirspec data .
we convolved the product of the rotationally - broadened ucd template and the telluric model with an estimate of the spectrograph line spread function ( lsf ) .
finally , we used quadratic interpolation to place the model on the lower resolution nirspec wavelength grid , which we define through polynomial mapping of pixel to wavelength . in total the model of each individual spectrum
has the following 11 free parameters : four for the polynomial mapping of pixel to wavelength , one for an overall flux scaling , four for a flux gradient across the spectrum , one for the lsf fwhm under the assumption that the lsf is a normalized gaussian , and one for the ucd rv .
we also had fixed parameters for the scaling of the telluric model with airmass , which we define later in this section , as well as the @xmath4 and effective temperature , @xmath59 , for each ucd , which we determined separately and fixed in all subsequent analyses .
we fit our model to the nirspec data in a least squares sense using an implementation of the amoeba @xcite fitting method to minimize @xmath45 .
we began our analysis of the nirspec data by selecting a training sample of 200 a star observations acquired over the course of the survey at a range of airmasses from 1.0 to 2.0 .
examples of a star spectra at a range of airmasses are shown in figure [ astars ] .
we modeled these observations without including the ucd template in order to refine our fitting procedure , determine the overall distribution of the best - fit wavelength and lsf parameters , and model the changes of the depths of telluric lines with airmass . starting from the nominal 10 model parameters ( no rv ) we added an additional free parameter for the scaling of the depths of the telluric lines with airmass .
the @xcite data is at airmass ( am ) of 1.5 , but our data were acquired at a wider range of airmasses . at higher airmass the optical depth of the atmosphere increases and we expect the telluric line depths to increase .
we assumed a one parameter scaling of the depths of the telluric lines from the am=1.5 model ( @xmath60 ) with airmass @xmath61 .
based on the fits to the a star training sample , we found that the telluric line depths observed at the summit of mauna kea , shown in figure [ tau ] , were well fit with @xmath62 .
after this initial determination of the telluric scaling we adopted this relation for @xmath63 for all of the subsequent fitting of nirspec spectra and fixed this parameter in the modeling of each ucd spectrum . in order for our fitting procedure to successfully converge on the correct model parameters , excellent initial estimates of the parameters were required .
the a star training sample allowed us to determine the average model parameters related to the spectrograph and select good initial values for each parameter .
we found that our nominal model resulted in a star fits with @xmath64 . adding additional parameters for the wavelength solution did not significantly improve the overall quality of the fits .
we also found that conducting an initial cross - correlation of the first 200-pixel chunk with a nominal model of a nirspec a star observation allowed for the determination of the zeroth - order term in the wavelength solution to better than 0.1 of a nirspec pixel , sufficiently precise for amoeba to reliably converge on the correct wavelength solution .
we investigated how the lsf changes across the spectral order by fitting portions of a star spectra independently . while the fwhm of the gaussian lsfs across the spectra change with time , we found that the ratios of the fwhm of the best - fit gaussian lsfs in different portions of the spectra were relatively constant so that a single fixed parameter could be used to describe the slow change in the width of the lsf across the order . by looking at the average residuals of the fits to all 200 a stars we also identified individual telluric lines that did not follow the scaling with airmass . in figure [ fig2 ] we show four lines that are likely not @xmath65 absorption features but may be features due to @xmath66 @xcite .
we excluded a small spectral region ( ten pixels ) around each of these features in all of our fitting of the ucd spectra by assigning zero statistical weight .
the residuals of the model fits to the a star sample are shown in figure [ fig2 ] . with our instrumental setup a fringe - like modulation was often seen in the extracted spectra and is clearly visible in the a star residual around 2.314 @xmath29 m in figure [ astars ] .
this pattern is likely due to an internal reflection in an optical element near the detector @xcite and is generally described as the superposition of sinusoidal patterns with amplitudes of roughly @xmath67 and periods of approximately @xmath68 nm . an additional complication is that the spatial frequency of the fringe pattern is similar to the spatial frequencies of absorption features seen in slowly rotating ucds , so it can not be easily removed without degrading the signal that we wish to model .
like @xcite we found that the fringing pattern varies somewhat over time in phase , frequency , and amplitude . assuming that the fringe signal is multiplicative ( as opposed to additive ) we built a model of the average fringe signal in wavelength space by averaging the a star residuals ( @xmath69 ) in bins of width @xmath70 nm .
this model , shown in figure [ fig2 ] , is fixed in wavelength space and has an amplitude of approximately @xmath67 and is quasi - periodic with a dominant period of @xmath68 nm . including this fringe model in the fitting of the a star sample resulted in sigificant improvements in @xmath71 for the highest s / n spectra though had negligible impact on the resulting overall distribution of the best - fit model parameters .
given that the fringe pattern is a quasi - periodic multiplicative modulation it is possible that the average shapes of the telluric lines , and therefore the resulting wavelength solutions , could be biased as a function of the relative phase of the fringe and the telluric absorption features .
at the same time , the fact that the fringe model is not strictly periodic could mean that this effect averages out over the spectrum , reducing the impact on the resulting fits .
given the small amplitude of the fringe model compared to the s / n of our a star observations ( s / n@xmath72 ) it is perhaps not surprising that it is not an important factor in our fits .
we fit the ucd spectra following an iterative process using the average parameter values determined from the a star analysis as the starting parameters for amoeba . as with the a star analysis
, we used the first 200-pixel chunk of each spectrum to estimate the zeroth - order term of the wavelength solutions by cross correlating against a nominal telluric model . this first 200-pixel chunk
( 2.585 to 2.592 @xmath29 m ) of the ucd spectrum is relatively devoid of stellar absorption features and so fitting this chunk to the telluric - only model was useful both for determining the starting wavelength position as well as the single lsf fwhm parameter .
we also produced an initial rv estimate by cross correlating a spectral region with rich co features ( 2.298 to 2.305 @xmath29 m ) against a fiducial ucd model at zero velocity .
this step , which we found necessary for ensuring convergence of the fitting process , provides a rough ( @xmath7310 km s@xmath1 ) estimate of the rv that includes shifts due to barycentric motion .
we estimated the @xmath59 and @xmath4 for each ucd in a two step process .
we began by fitting each spectrum of each object to a grid of 360 ucd models spanning @xmath74 k and @xmath75 km@xmath1 .
for each nirspec spectrum we found the global minimum @xmath45 in the @xmath59 and @xmath4 grid resulting in one estimate of each parameter for each spectrum . using these initial estimates we set a single @xmath59 for each object by selecting the ucd model that produced the lowest average @xmath71 values over all of the spectra the object .
with @xmath59 fixed for each object , we ran a second set of fits over a finer grid in @xmath4 and then fit for the minimum of the resulting curve of @xmath71 as a function of @xmath4 to estimate the best - fit @xmath4 for each spectrum .
we adopted the simple average of the individual estimates from each spectrum as the fixed @xmath4 of the ucd and the scatter of those estimates as the error on the @xmath4 .
these two parameters , @xmath59 and @xmath4 , were then fixed for all subsequent analyses .
we determined the lower limit on @xmath4 , set by the resolution of nirspec , by estimating the value below which changes in @xmath4 did not improve the @xmath45 of the fits to ucds that are known to be slow rotators . with the global ucd parameters fixed ( @xmath4 and @xmath59 ) for each target , we estimated the rv of each observation of each target using the same fitting process .
each spectrum was fit in two stages , rejecting outliers following an initial fit and then fitting again using the best fit parameters from the first fit as the new starting parameters .
we conducted extensive tests using artificial spectra to ensure that the correct minima were being found by amoeba by conducting fits with fixed wavelength solutions over a large , high - resolution parameter space .
we generated the artificial spectra based on the wavelength solutions found in the a star analysis , the synthetic ucd templates over a range of @xmath59 and @xmath4 , and noise properties representative of the actual nirspec data .
we found that with good starting values our amoeba fitting procedure reliably converged on the true minimum of @xmath45 and the correct model parameters .
the formal reduced @xmath45 of the ucd fits fall in a wide range ( 2@xmath76 ) . unlike with the a star analysis , where the @xmath45 is likely dominated by the noise properties of the nirspec detector and limitations in our lsf model , the ucd fits may be dominated by the mismatch between the theoretical stellar templates and the ucd and we expect some larger values of @xmath45 .
for example , systematic discrepancies are sometimes seen in the structure of the co bandhead or in the depths of individual co features longward of the bandhead .
we emphasize that systematic deviations between the spectra and the theoretical models may not be shortcomings of the models themselves but rather a symptom of the small range of our library of synthetic templates in terms of @xmath77 , @xmath78 , and metallicity .
an example of a nirspec spectrum , the best fit model , and the residuals is shown in figure [ panel ] and the top panel of figure [ empiric ] . we estimated the statistical uncertainty on each rv measurement , @xmath79 , based on the photon - limited doppler precision ( pldp ) presented in @xcite @xmath80^{-1/2}\ ] ] where the sum is over all pixels , @xmath81 is the rate of change of the model flux at a given pixel , in velocity units , and @xmath82 is a fractional noise term . here , @xmath83 is the ucd ( or telluric ) component of the best - fit model for each spectrum . in the case of photon noise alone
@xmath84 where @xmath44 is the data in adu and @xmath85 is the detector gain .
we estimated the pldp of the best fit model by evaluating the telluric and ucd components of the model separately and adding the two error estimates in quadrature .
this accommodates the case of a high s / n observation of a rapidly rotating object where the wavelength solution may be determined precisely from the deep telluric lines but the rv is only poorly determined from the broad stellar features . for the typical s /
n of our ucd observations we estimate that the telluric lines themselves limit the rv precision to @xmath86 m s@xmath1 .
our data have significant sources of noise beyond just photon noise . instead of assuming photon noise alone , we estimated the noise term @xmath87 from the residuals of the best fit model [ @xmath88 .
the residuals could be dominated by systematic discrepancies between the model and the data , which could result in an over estimation of the noise term based the rms of @xmath89 alone . to remove such systematic residuals we first smoothed the residuals
[ @xmath90 with a boxcar filter of width five pixels and then estimated the noise term @xmath91 we applied barycentric corrections to the individual rv estimates calculated using the code _ bcvcorr _ ( g. torres ; private communication ) and then combined observations ( generally nod positions a and b ) from the same epoch using a weighted mean .
based on the standard deviations of the rv measurements of 43 of our targets with observations on three or more epochs , @xmath92 km s@xmath1 , and excluding known or suspected variables , shown in figure [ rmshist ] , we estimate our rv precision to be approximately 100 - 300 m s@xmath1 for slowly rotating ucds . in figure [ vsinrms ]
we compare the measured standard deviation of the rvs of each of our targets to the estimated @xmath4 .
as expected , our rv precision degrades significantly for rapidly rotating l dwarfs . during the course of our survey we also observed the bright ( k=5.08 ) , slowly rotating ( v@xmath93 km s@xmath1 ) m3 dwarf gj 628 as an rv standard
this object is more massive than the stars in our ucd sample , falling outside the @xmath59 range of our synthetic templates . for the spectral
fitting we used a synthetically generated m dwarf template with @xmath94k , @xmath95 computed from updated and improved nextgen @xcite models ( t. barman , priv .
comm . ) from our analysis of 11 epochs of observations of gj 628 we found an rv rms of 50 m s@xmath1 over a period of 800 days , as shown in figure [ gj628 ] .
we note that the scatter of these rv measurements is well - described by the pldp error estimates obtained using the technique described in section 4 [ @xmath96 indicating that at least for bright , slowly rotating objects we are achieving an rv precision very close to the photon limit . to reliably estimate the statistical significance of any rv variations we detect in our ucd sample it is necessary to understand the underlying errors , both systematic and statistical , on our individual measurements .
we have estimated the statistical errors on our individual rv measurements , @xmath79 , directly from the data , but these estimates do not take into account systematic effects that may occur between epochs . to investigate the overall statistical properties of our measurements we selected a sub - sample of objects that have observations on three or more epochs and are not known or suspected binaries . assuming the null hypothesis that each of these ucds has a constant rv , using the empirically - determined internal errors , @xmath79 , for each of the 207 measured rvs we calculated @xmath97 for @xmath98 degrees of freedom ( assuming one parameter for the constant rv of each target ) .
if we have excluded all of the actual rv variables from this analysis , then this value of @xmath99 indicates that our statistical error estimates are too small and that there is a significant systematic contribution to be included in our overall error model . the overall error distribution for this sub - sample is shown in figure [ residnorm ] , which shows that there are significant non - gaussian tails at @xmath100rv@xmath101 .
we scaled all of the pldp errors estimates for the ucds by a factor of @xmath102 , resulting in a reduction of the @xmath99 to 163.6 for the same number of degrees of freedom @xmath103 $ ] . in some cases it is clear that the scaled errors are too large .
for example , the scatter about the best fit orbital solution for the binary 2m0320@xmath304 , described in section 6.1 , is 135 m @xmath1 while the smallest error estimate for a single point in the fit is 178 m s@xmath1 . despite this possible overestimation , we used the scaled rv error estimates for all subsequent analyses of the ucd rv measurements . based on our observations of the rv standard
gj 628 we conclude that our modeling process can produce rv measurements near the photon - limit over long timescales and that the worse overall rv precision obtained for the ucds could be due to a number of factors .
the tails of the distribution of @xmath104 could be the result of real rv variability since we have only excluded known and suspected binaries from our sub - sample .
while the theoretical template used to model gj 628 is a very good match for its spectrum , mismatch between the theoretical templates and the actual spectra of the ucds could lead to worse rv precision .
lastly , it is possible that the much longer integration times used for the ucd observations compared to the gj 628 observations lead to systematic effects that are not encompassed in our model . in an effort to increase the overall precision of our rv measurements , as well as to address some technical issues that may be important for efforts to achieve high rv precision in the nir with nirspec or similar instruments
, we experimented with some modification to the standard fitting process described in section 4 .
the first was the inclusion of the fringe model derived from observations of a stars into the ucd fits . including this fringing model in the a star fitting process led to significant improvements to the resulting @xmath71 , though had negligible impact on the overall statistical properties of the resulting model parameters .
similarly , including the fringe model in the analysis of the gj 628 observations did not result in a statistically significant decrease in the resulting rv scatter . while the a star and gj 628 observations typically have s / n@xmath72 , the ucd observations have @xmath105s / n@xmath106 .
the low - amplitude flux modulation of the fringe pattern is small compared to the read noise and photon noise and so was not expected to significantly impact the fitting process .
we did experiment with including the fringe model in the flitting of the ucd spectra and found that the overall statistical properties of the resulting rv measurements were consistent with or without the fringe model and that the photon - limited errors still needed to be scaled by a factor of @xmath107 to account for the observed scatter in the rv measurements of individual objects .
the fringe model was not included in the final ucd rv results presented here .
while our theoretical templates are generally a very good match for the ucd spectra , for some individual objects there are significant systematic discrepancies in the shapes of the spectral features .
this is most likely due to the fact we are only fitting a small library of synthetic templates to our spectra and a wider range of @xmath77 , @xmath78 , metallicity values , and line damping treatments could significantly improve the fits for some objects .
if we have multiple observations of an object , and we can assume that the object has a constant rv , then it is possible to build an empirical spectral template from the observations themselves .
we began by fitting the spectra using the theoretical templates following the standard procedure described in section 4 . assuming that the wavelength solutions were sufficiently well - determined by this initial fit we divide the data by the telluric component of our best fit model , resulting in a normalized ucd spectrum that is free from atmospheric absorption features .
we corrected the wavelength solutions for the known barycentric velocity of each spectrum and then averaged all of the normalized spectra in 0.01 nm bins to create an empirical spectral template .
for a slowly rotating ucd , where @xmath4 is comparable to or smaller than the spectrograph resolution , it is necessary to account for the broadening of the stellar spectral features by the lsf of the spectrograph . to do this we assumed a gaussian lsf with fwhm=@xmath108 nm and carried out an iterative deconvolution following @xcite on the empirical template in an attempt to recover the un - broadened spectrum . using this method we created an empirical template for the rapidly rotating ( @xmath109 km s@xmath1 ) l dwarf 2m0652 + 47 and found that the overall fit residuals were reduced to the level of @xmath67 .
we also generated templates for more slowly rotating objects and a comparison between a theoretical template and an empirical template for the slowly rotating l dwarf 2m0835@xmath308 is shown in figure [ empiric ] . while this technique did in some cases
result in templates that were significantly better fits to the observed spectra , there are a number of drawbacks .
the first is that a large number of spectra are required to produce the empirical template , preferably more than five , in order to robustly average in wavelength bins .
the second is that we began by assuming that the object has a constant rv .
intrinsic doppler shifts will result in a broadened spectral template and , particularly if the number of spectra is small , the empirical template may result in biased rv estimates .
we found that using empirical templates to fit the subset of our sample with observations on five or more epochs did not yield rvs with a smaller dispersion . with our current data
the creation of empirical templates may be most useful when looking for temporal changes in the residuals of the fits , which could be evidence for a faint companion .
as the precision of rv measurements at optical wavelengths has improved to the level of 1 m s@xmath1 it has become clear that modeling the shape of the spectrograph s lsf is critically important .
@xcite used a basis set of 11 gaussian functions to model the subtle changes in the lsf asymmetries in their @xmath110 cell observations .
spectrograph lsf asymmetries may be inherent to the instrument or , in a slit spectrograph , they may arise from guiding errors inducing variations in the stellar position along the slit .
we modeled the nirspec lsf as a symmetric , gaussian function that has a linear variation in width across the order .
we experimented extensively with using multiple gaussians to describe a more complex lsf in a manner similar to @xcite .
owing to the limited s / n of our data , we could not reliably model the lsf asymmetry in either the a star or ucd spectra .
future improvements in the rv precision obtained using this technique will require a detailed modeling of the spectrograph lsf but the current spectral resolution and s / n may not motivate such an analysis .
the measurements from our nirspec survey , listed in table 2 , represent the largest available sample of high - resolution , high - s / n , nir observations of l dwarfs .
the primary goal of this survey has been the detection of rv variations due to unseen companions . with an overall rv precision of approximately @xmath111 m s@xmath1 for slowly - rotating ucds
, we are sensitive to many types of binary systems .
the rv semi - amplitude , @xmath112 , of the primary ( more luminous ) star in a spectroscopic binary ( or planetary system ) is @xmath113 the targets in our sample are expected to have masses from near @xmath114 down to the late - l dwarfs at @xmath115 @xcite . if our survey is sensitive to signals with @xmath116rv@xmath117 km s@xmath1 , then we may detect systems ranging from equal - mass binaries with periods of up to a decade to giant planetary companions with orbital periods of several weeks or less .
we expect that the majority of our targets are not spectroscopic binaries @xcite and therefore will not exhibit rv variations . with the scaling of our pldp error
estimates our rv measurements are fully compatible with this hypothesis .
the calculated @xmath99 for each ucd , assuming constant rv , and corresponding probabilities are given in table 3 .
we identified five with large @xmath99 having probabilities @xmath118 , the statistical probability of getting a smaller value of @xmath99 , greater than 0.999 .
we note that three of these systems exhibiting significantly large @xmath99 are either known or candidate binaries .
two of these are known binaries already in the literature ( 2m0746 + 20 , lsr1610@xmath30040 ) , one is a new binary identified in the early stages of this survey ( 2m0320@xmath304 ) , and one target exhibits a possible long - term rv trend ( 2m1507@xmath316 ) .
lsr0602 + 39 exhibits statistically significant rv variations that show no evidence for periodicity or a long - term trend .
this object is an l subdwarf discovered in the galactic plane by @xcite and , based on the detection of li in the spectrum , is thought to be a brown dwarf .
possibly because of its low metallicity , our theoretical spectral templates are a comparatively poor fit for the observed spectrum of this object , particularly around the co bandhead , and as a result our theoretical error estimates are possibly underestimated .
we also compared our rvs to the few that exist in the literature , including those from @xcite , to look for any additional evidence of long - term trends .
while we found overall good agreement with our measurements we note that the rv for kelu-1 ( 2m1305@xmath325 ) reported by @xcite from observations in 1997 differs by about 10 km s@xmath1 from our measurement in 2003 .
kelu-1 is a binary , or possibly triple , system with an estimated orbital period of 38 years @xcite , with an expected rv semi - amplitude of 3 - 4 km s@xmath1 .
we found no such offset for the other objects observed in common with @xcite .
measuring the reflex motion of the primary component of a single - lined binary ( sb1 ) system , @xmath112 , allows us to measure the mass function , a transcendental equation that involves @xmath119 , @xmath120 , and @xmath121 @xmath122 where @xmath123 is in days and @xmath112 is in km s@xmath1 . in a double - lined spectroscopic binary system ( sb2 )
the measurements of @xmath112 and @xmath124 can be combined to directly estimate the mass ratio @xmath125 .
additional observations , such as astrometric observations of the binary orbit , are required to determine @xmath121 and to measure any of these quantities independently .
we used a non - linear levenberg - marquardt fitting scheme @xcite to fit the six keplerian orbital parameters to our data and analyze the rv variations of four of our targets .
the six orbital parameters we fit are : @xmath112 , the rv semi - amplitude of the primary ; @xmath126 , the systemic velocity of the center of mass of the system ; @xmath127 , the longitude of periastron ; @xmath128 , the eccentricity ; @xmath60 , the time of periastron passage ; @xmath123 , the orbital period .
we discovered the sb1 spectroscopic binary system 2m0320@xmath304 early in our survey @xcite and its binarity was suggested independently using spectral fitting methods by @xcite . with a relatively short period ( @xmath129 d ) and large rv semi - amplitude ( @xmath130 km s@xmath1 ) , this system was easily detected in our nirspec data and was observed on 16 epochs during the course of our survey .
we fit the spectroscopic orbit using rv measurements that are improved over those in @xcite and found consistent results with a scatter about the fit of @xmath131 m s@xmath1 , improved from the @xmath132 m s@xmath1 scatter found using the analysis pipeline described in @xcite .
the new rv measurements and the orbital solution are shown in tables 4 and 5 and figure [ 0320 ] .
based on the spectral analysis of @xcite , this system is thought to be composed of a late - m dwarf and an early - t dwarf with masses @xmath133 and @xmath134 . as a single - lined system , our spectroscopic orbit results in a mass function and without additional observations to determine @xmath121 ,
the individual masses , or their ratios , ca nt be directly measured . while this system is expected to be too narrowly separated ( @xmath13517 mas ) to be resolved with adaptive optics systems on current telescopes , with more sensitive observations
the spectral lines of the secondary should be detected . in that case
, the ratio of the masses and the ratio of the brightnesses can be determined using a technique like todcor @xcite .
such measurements would allow for some of the first direct tests of coeval ucds at field ( @xmath33gyr ) ages , providing important constraints on theoretical models .
the flux ratio at @xmath49-band , where our nirspec data were taken , is expected to be between @xmath136 and @xmath137 , and thus may be below our detection limit .
the estimated mass ratio of @xmath138 @xcite would indicate a maximum velocity separation between the two components of @xmath139 km s@xmath1 , potentially resolvable with nirspec . in order to search for the spectral lines of the secondary we created an empirical spectral template for 2m0320@xmath304 following the same method described in section 5.1 with the additional step of correcting the wavelength solutions for the sb1 orbit determined above .
we found no evidence for temporal variations in the residuals of the fits .
using an empirical template to fit the nirspec observations of the rapidly rotating ( @xmath140 km s@xmath1 ) object 2m0652 + 47 we found that the residuals to the fits were at the level of @xmath67 .
for rapidly rotating objects any changes in the spectrograph lsf have a small impact on the empirical template generation .
this is not the case for 2m0320@xmath304 , where @xmath141 km s@xmath1 is slightly larger than the width of the lsf . in order to quantify the impact of this effect we studied fits with an empirical template for the nirspec observaitions of 2m0835@xmath308 ( @xmath142 km s@xmath1 ) .
in this case we found fit residuals using the empirical template were as large as @xmath143 in the cores of co features . in the future it may be possible to create an empirical template by deconvolving the individual spectra with a more realistic estimate of the lsf , increasing our sensitivity to faint companions .
lsr1610@xmath30040 ( lsr1610 ) is a known binary with a low - mass primary and an orbital solution based on fits to the astrometric motion of the center of light of the system @xcite .
we combined our four measurements with two others from the literature @xcite and found good agreement between our rv measurements and the orbital parameters determined from the astrometric orbit alone .
the single measurements from @xcite derived from fitting individual atomic resonance lines in the optical spectrum deviates significantly from the expected spectroscopic orbit and is excluded from the following analysis .
the single measurement from @xcite , also at optical wavelengths , is nearly coincident with one of our rv measurements and the two agree within 1@xmath144 .
we performed a monte carlo simulation to estimate the parameters of the spectroscopic orbit by varying @xmath123,@xmath128 , @xmath145 , and @xmath127 according to the quoted errors in @xcite while also varying the rv measurements according to their quoted errors and fitting for @xmath112 , @xmath60 , and @xmath126 .
the rv measurements and best fit spectroscopic orbital orbital parameters are given in tables 6 and 7 and the orbital solution is shown in figure [ lsr16 ] .
the primary of the system is expected to be very low in mass and assuming that the flux of the secondary is negligible @xcite estimate @xmath146 m@xmath147 using the mass - luminosity relation ( mlr ) from @xcite .
the orbital motion of the center of light from @xcite , denoted @xmath148 , is related to the physical properties of the system as @xmath149=0.276 au\ ] ] based on the parallax from @xcite the distance modulus for lsr1610 is @xmath150 and @xmath148 is known in absolute units . combining the astrometric orbital period , eccentricity , and inclination with the rv semi - amplitude , @xmath112 ,
directly determines the semi - major axis @xmath151 .
the spectroscopic mass function ( eq . 5 ) and the relation for @xmath148 are two equations in three unknowns ( @xmath119 , @xmath120 , and @xmath152 ) since the spectroscopic mass function combined with the known inclination determines @xmath120 as a function of @xmath119 . these relations together determine the i - band light ratio @xmath153 as a function of @xmath119 . in table 8 we list @xmath154 and @xmath152 derived from the combination of the astrometric and spectroscopic orbits for a range of @xmath119 .
lsr1610 has been described as having `` schizophrenic '' spectral properties and is in many ways an enigmatic object @xcite .
the spectral features in the optical and nir are indicative of a mildly metal poor mid - m dwarf with a number of unusual atomic absorption features . in figure [ lsr16spec ]
we compare our high - resolution @xmath49-band spectra of this object to the spectrum of the m8/l0 dwarf 2m0320@xmath304 . while the overall structure of the co bandhead and the strengths of the individual co features is quite similar in these objects ,
we interpret the lack of absorption features blueward of the bandhead as possible evidence for low metallicity .
@xcite found that the combined light of the system falls very near the locus of low - mass stars on color - magnitude diagrams ( cmds ) , both @xmath155 vs. @xmath156 and @xmath157 vs. @xmath158 , meaning that it has roughly the expected luminosity and colors for an m dwarf .
at the same time , they attribute a @xmath159 flux that is significantly suppressed to metal pollution by accretion of material from a hypothetical agb star that could also be responsible for prominent al lines in the nir spectrum . here
we summarize what we know about this system and attempt to provide some possible explanations of the observed properties . *
if we assume that the primary is indeed low in mass , say @xmath160m@xmath161 , then @xmath162 . if we assume an average value of @xmath163 then the absolute magnitude of lsr1610a is @xmath164 mag .
our analysis constrains the mass ratio ( @xmath165 ) of the system to be @xmath166 for @xmath167m@xmath161 .
* mlrs are thought to be least sensitive to metallicity at nir wavelengths .
the updated @xmath49-band mlr from @xcite would indicate a mass for lsr1610a of @xmath168m@xmath161 after correcting for the light of lsr1610b , somewhat larger than the estimate based on the @xcite relations of @xmath169m@xmath161 , though @xmath170 falls outside the range over which the @xcite relation is formally defined .
* @xcite found good general agreement between theoretical isochrones for old , low - metallicity stars from @xcite and the absolute magnitudes of ten low - mass subdwarfs with measured parallaxes . using slightly metal poor lyon models ( [ m / h]=-0.5 , t=10 gyr ) we estimated the mass of lsr1601a to be @xmath171m@xmath161 and found a similar mass if the system is 1 , 5 or 10 gyr .
these models also agree with the observed @xmath172 color of the combined light of this system .
this object has a very large space velocity ( @xmath173 km s@xmath1 ) , and based on the kinematic arguments in section 7 we expect that this system is part of an older , thick disk population , making it unlikely that it is in fact very young .
based on the available observational evidence it remains difficult to explain lsr1610 . from the empirical mlrs and theoretical isochrones
it seems that lsr1610a is a low - mass star with @xmath174m@xmath161 . for the mass range @xmath175m@xmath161
the spectroscopic mass function requires that @xmath176 , a somewhat implausible scenario if @xmath177 since the theoretical expectation is that the more massive component should be more luminous across the optical and infrared .
the problem is alleviated somewhat if in fact lsr1610a is more massive than expected .
based on the available observational evidence we propose the following possible scenarios for lsr1610 : * the distance of lsr1610 could be underestimated .
this would increase the mass estimate based on the isochrones and the mlrs and result in @xmath178 .
for example , if m@xmath179 then @xmath178 and the flux difference @xmath180 mag is consistent with theoretical models .
this may seem an implausible explanation since @xcite and @xcite find consistent parallaxes .
* lsr1610b is a very unusual object . in principle lsr1610b
could be an old compact object but would have to be very faint in @xmath159 ( @xmath181 ) yet relatively bright in i band ( @xmath182 , @xmath183 ) .
based on the known properties of low - mass white dwarfs @xcite we deem this scenario unlikely .
@xcite reached a similar conclusion .
it is possible that in the near future this system could be resolved with aperture masking interferometry ( e.g. @xcite ) , resulting in a direct measurement of the masses of both components .
we also carried out an empirical template analysis for this system , correcting the wavelength solutions for both the barycentric motion and the sb1 orbital solution .
the expected velocity separation is rather large for this system ( @xmath184 km s@xmath1 ) and the flux ratio in k band is expected to be 5:1 making lsr1610 an excellent candidate for a double - lined system . unfortunately , we have only one epoch of observations where the orbital phase is favorable for resolving the lines of the secondary and those spectra were obtained under poor observing conditions and are of relatively low s / n .
we found no evidence for the lines of the secondary in the residuals of the fits at this epoch using an empirical template generated using the technique described in section 5.1 .
this object is a very nearby mid - l dwarf with a parallax of @xmath185 mas @xcite .
our initial rv measurements of this object exhibited a statistically significant rv trend .
we obtained additional nirspec measurements under cloudy conditions in april and may , 2009 , resulting in a total time baseline of more than six years .
the amplitude of the rv variation is close to the limits of detection with our current technique , but we rule out constant rv [ @xmath186 .
the measurements , given in table 9 , are well - fit by a linear rv trend with a slope of @xmath187 m s@xmath1 per year . using a monte - carlo simulation we estimated the false alarm probability of observing a slope @xmath188 m s@xmath1 per year to be 2.2@xmath42 .
this linear trend is also consistent with a single rv measurement from @xcite obtained in 2000 , though this optical measurement has a very large error bar ( @xmath189 km s@xmath1 near hjd 2451661 ) .
@xcite report a velocity difference between 2000 and 2004 of 2.5 km s@xmath1 for this object , which is incompatible with the velocity trend seen in our data , though we note that these measurements also have large errors bars .
we calculated the secular rv acceleration ( @xmath190 ) for this object following @xcite and estimated the maximum amplitude of this effect to be less than 0.6 m s@xmath1 yr@xmath1 , far smaller than the observed trend .
the trend seen in our nirspec observations could be indicative of a very long period system with @xmath191 d , but we note that within our sub - sample of 46 objects observed on three or more epochs we may expect to observe at least one long - term slope with a false - alarm probability of @xmath192 . the mass of the l5 primary is poorly constrained based on photometry alone , but comparing absolute magnitudes and the temperature ( @xmath193 , @xmath194 , and @xmath195 from @xcite ) to models from @xcite and @xcite , the minimum mass is expected to be in the range @xmath196 depending on the age of the system , assuming ( based on the object s kinematics ) @xmath197gyr . based on the lack of li absorption , @xcite determined that this l dwarf has a minimum mass of @xmath198 .
if we assume that the binary has near equal mass components , as is observed to be the case for many low - mass binaries @xcite , with @xmath199 , then the mean orbital separation for a circular orbit would be @xmath200 au if @xmath191 d. at a distance of 7.3 pc this corresponds to an angular separation of @xmath201 .
unless the system is close to edge - on and observed at a very unfavorable phase , then such a binary would have been readily resolved in the high - resolution imaging observations presented by @xcite and @xcite who found no luminous ( @xmath202 mag ) companions to 2m1507@xmath316 over a range of separations @xmath203 . approximating the detection limit for faint companions from @xcite as @xmath204 and assuming the 5 gyr models from @xcite for the secondary and 5 gyr models from @xcite for the primary
then the non - detection constrains the mass ratio of the system to be @xmath205 .
it is also possible that the period of the system is much longer than 5000 d , resulting in an angular separation too large to be detected in the narrow fields of view of high - resolution imaging surveys .
using nir imaging data obtained in 2005 and described in @xcite we detect only one source in an annulus of @xmath206 to @xmath207 down to limiting magnitude of @xmath208 and @xmath209 .
this source is also visible in archival 2mass observations from 1998 and does not share the large ( @xmath210 year@xmath1 ; @xcite ) proper motion of 2m1507 - 16 . the orbital motion of the two components of this tight ( @xmath211 mas ) binary system has been directly observed with high - resolution imaging , resulting in the measurement of the sum of the masses and the first dynamical mass estimate for an l dwarf @xcite .
based on high spatial resolution observations with hst , vlt , and gemini , the orbital period of this system is estimated to be @xmath212 days , so our nirspec observations , shown in figure [ 2m0746 ] , span a considerable fraction of a period .
the fit to the astrometric orbit determines the sum of the masses , @xmath213 , and the semi - major axis @xmath214 au .
the components of this system are resolved and the flux ratio of the components is measured to be 1.6:1 at @xmath49 band . based on the orbital parameters determined in @xcite and the mass estimates from @xcite , the expected rv separation at periastron passage is @xmath215 km s@xmath1 . using nirspec with
ao @xcite resolved this system and obtained rv measurements for both components . combining these measurements with the astrometric orbit
yields direct measurements of the masses of both components , though for the case of 2m0746 + 20 the errors on the mass estimates are relatively large .
while the flux ratio of the system is favorable for detecting the spectral lines of the secondary , the velocity separation is small compared to the nirspec resolution , particularly for observations that do not coincide with the periastron passage in 2003 . in this case where both components are of similar brightness , are expected to have similar spectral features , and are not resolved in velocity , we are effectively measuring the rv of the combined light of the system . if the components have exactly equal masses , spectral features , and luminosities , we would observe no rv variations at all . as a result of this combined light effect
we do not necessarily expect to measure the true rv of 2m0746 + 20a using our technique . using the orbital parameters from the astrometric orbit from @xcite we fit for @xmath112 and @xmath126 assuming that the light from 2m0746 + 20b has a negligible impact on the measured rv and found @xmath216 km s@xmath1 and @xmath217 km s@xmath1 .
the resulting rv orbit is shown in figure [ 2m0746 ] .
we emphasize that these orbital parameters are very likely biased by the influence of 2m0746 + 20b , in particular our estimate of @xmath112 is expected to be too low .
we carried out a simulation to assess the impact of a marginally - resolved secondary by fitting mock spectra that contained light from a secondary with a flux ratio of @xmath218 and velocity offsets of between @xmath219 km s@xmath1 from the primary .
we found that such companions significantly influenced the resulting rv measurement from fitting the combined light , @xmath220 , and that @xmath221 , meaning that our rv measurements near periastron passage could be biased by up to a few km s@xmath1 .
our observations can also be used to study the statistics of the rotational and space velocities of ucds .
the rotational velocities of brown dwarfs and low - mass stars are important for understanding the angular momentum history of these objects .
measurements of a large number of ucd @xmath4 values exist in the literature , though the measurements were made using techniques different from the one employed here .
@xcite estimated rotational velocities by fitting the rotationally - broadened feh stellar absorption features near @xmath222 m using data from hires at keck i and uves at vlt .
these optical data are of higher resolution than our nirspec data resulting in @xmath4 sensitivity down to 3 km s@xmath1 .
both @xcite , using vlt and the uves spectrograph , and @xcite , using keck and nirspec , follow the traditional technique of cross - correlating their spectra with a slowly rotating template and estimating @xmath4 from the width of the resulting cross correlation function .
as shown in figure [ vsin ] , we find excellent overall agreement between our @xmath4 estimates and the values reported in the literature , including those in @xcite .
@xcite explored possible patterns in the rotation of m and l dwarfs as a function of spectral type in an effort to better understand the evolution of the angular momentum of ucds as they age .
the fact that both young and old l dwarfs are often rapid rotators indicates that their rotation differs from that of sun - like stars .
more massive stars lose angular momentum through solar winds , slowing as they age , but older field l dwarfs still appear to be relatively rapid rotators compared to sun - like stars of similar ages .
@xcite propose a braking mechanism that decreases in efficiency at the cooler atmospheric temperatures of ucds and is very inefficient in mid- to late - l dwarfs , where the deceleration timescales become comparable to the age of the universe . at the cool temperatures of ucds the stellar atmospheres are largely neutral , with few ions , reducing the strength of the coupling between the magnetic fields and the atmosphere and therefore reducing the strength of the braking mechanism .
this model explains the lack of l dwarfs later than l3 found by @xcite to rotate slower than @xmath223 km s@xmath1 . in figure [ sptvvsin ]
we show our projected rotational velocities against spectral type as determined from optical diagnostics , the same spectral types used by @xcite , along with other measurements from the literature .
we also see some evidence for increasing @xmath4 for objects with spectral types later than l3 .
we do , however , find four mid - l dwarfs that appear to be very slow rotators with @xmath224 km s@xmath1 : 2m0355 + 11 , 2m0500 + 03 , 2m0835 - 08 , and 2m1515 + 48 .
the spectra of these l dwarfs , shown in figure [ slow ] , exhibit sharp , narrow co features indicative of slow rotation and their spectra are relatively well fit by our theoretical ucd models .
the l6 dwarf 2m1515 + 48 also has a very large space velocity , a potential indicator of old age .
the @xcite sample includes approximately 15 l dwarfs with spectral types later than l3 , comparable to our number .
it is possible that these results are entirely consistent and that our slow rotators are simply observed close to pole - on . comparing our @xmath4 measurements to those from @xcite for objects with spectral types later
than or equal to l4 with a two - sided k - s test indicates a probability of @xmath225 that the two samples are drawn from the same underlying distribution . studying the kinematics of a population of stars , in particular their 3d motions ,
is a powerful tool for understanding the age of that population as well as for identifying subgroups that may have distinct histories from the main population . as a result of gravitational interactions , the velocity dispersion of a population of stars
is expected to increase with time as it orbits in the galaxy .
models of ucds , and brown dwarfs in particular , have an inherent mass - age degeneracy that makes it difficult to differentiate between a old low - mass star and young brown dwarfs .
this means that very few individual ucds have reliable age estimates . since ucds are intrinsically very faint , the relatively bright ucds we observe are necessarily close to the sun and most have reliable proper motion , and sometimes parallax , measurements . using these measurements , the statistical properties of the kinematics of the ucd population can be determined and the age of the population estimated using calibrated age - dispersion relations @xcite . @xcite present a analysis of the space velocities of 841 ucds .
in this work the authors do not have rv information but rely on photometric distance estimates combined with proper motions to estimate the tangential velocity , @xmath226 . as pointed out by @xcite
the analysis by @xcite applies the results from @xcite by assuming @xmath227 when in reality the dispersion of the total velocity must be determined from the dispersions of the individual velocity components .
we combined our radial velocities with proper motion and parallax measurements from the literature and photometric distance estimates from @xcite to estimate the total space velocity , @xmath228 , as well as @xmath229 , @xmath230 , @xmath231 components following the transformation presented by @xcite .
we followed the right handed convention ( positive @xmath229 is toward the galactic center ) and we did not apply a correction to the local standard of rest .
the distribution of @xmath232 for 55 of our targets with distance and proper motion estimates from the literature is shown in figure [ vtot ] and the velocity components are listed in table 10 .
the distribution of @xmath228 is approximately gaussian with a significant tail of targets with @xmath233 km s@xmath1 . excluding these high velocity ucds we found that the average space velocity of the ucds in our sample is @xmath234 km s@xmath1 , similar to the mean l dwarf space velocity found by @xcite .
we estimated the velocity dispersions of our sample in each velocity component using a bootstrap simulation taking into account the reported errors on all of the measured quantities used to calculate @xmath229 , @xmath230 , and @xmath231 .
we calculated the @xmath235-weighted dispersions ( eqns . 1 - 3 in @xcite ) and estimated @xmath236 excluding the high velocity ucds . based on the results of the bootstrap simulation we estimated @xmath237 km s@xmath1 .
we used eqn . 16 from @xcite ( eqn . 3 from @xcite ) to estimate the age of our sample to be @xmath5 gyr ( @xmath238 confidence )
not including any systematic uncertainty in the age - dispersion relation .
this age is somewhat larger than the 3.1 gyr estimated by @xcite for their sample of m7-m9.5 dwarfs , though they conclude that @xmath14 of their objects are actually young brown dwarfs .
our sample of mainly l dwarfs is lower in mass and may have less contamination from young objects , possbily contributing to the differences in the estimated ages of our two samples .
our results are in excellent agreement with those of @xcite who used a similar method to estimate the age for a sample of 43 l dwarfs .
they also estimate the kinematic age of their sample to be approximately 5 gyr and discuss the impliciations of this result .
since nearby m dwarfs appear to have an age of approximately 3 gyr it is surprising that early l dwarfs , which , if below the hydrogen burning mass limit , will dim substanitally and move to later spectral types as they age , should be found to be older than m dwarfs .
possibly explanations for this proposed by @xcite include different initial velocity dispersions for m and l dwarfs , the influence of kinematic outliers in the estimation of the velocitiy dispersions , and non - gaussianity in the velocity distributions .
the high velocity ucds that we excluded from the @xmath228 analysis are themselves potentially very interesting
. objects with high velocities may be subdwarfs from an older , lower - metallicity thick disk or halo population .
in addition to lsr1610 we identified eight l dwarfs with @xmath233 km s@xmath1 listed in table 11 .
lsr1610 was one of the first known low - mass subdwarfs , and its @xmath173 km s@xmath1 exceeds all of the rest of the objects in our sample and based on its velocity components it is considered to be a member of the halo population . in figure
[ thin ] we compare the estimated uvw velocities to velocity ellipsoids for the thin disk and thick disk populations . while the majority of the ucds in our sample have kinematics consistent with the local thin disk population , seven have large negative v velocities , falling outside the @xmath239 velocity ellipsoid for the thin disk ( @xmath240 km s@xmath1 ) , making them candidates for membership in the older thick disk population .
thanks mainly to direct imaging surveys , we now know that the population of ucd binaries has several significant differences from that of binaries composed of sun - like stars .
these differences are summarized in @xcite and @xcite : @xmath241 ucd binaries tend to have mass ratios @xmath21 compared to @xmath242 for sun - like stars , @xmath243 there are very few ucd binaries with @xmath244 au , @xmath245 for ucds the distribution of binary separation peaks around @xmath22 au compared to @xmath246 au for sun - like stars , @xmath247 the overall fraction of binaries is @xmath248 for ucds compared to @xmath249 for sun - like stars . using a bayesian approach that assumes a parameterized underlying distribution for the properties of ucd binary systems , @xcite estimated that there is likely a small but significant population of small separation ( @xmath6 au ) ucd binaries that are not detected by imaging surveys or the rv surveys that have been conducted to date .
systematic rv surveys like our nirspec survey are important for constraining the binary fraction in this part of parameter space . an equal - mass ucd binary ( @xmath250m@xmath251 ) with an average separation of @xmath252 au
has an orbital period of 7 years and an rv semi - amplitude @xmath253 km s@xmath1 , potentially detectable in our survey .
we carried out a monte carlo simulation to estimate how efficiently our survey detects tight binaries and the overall rate of such systems . for our simulation we used a sub - sample of 40 targets from our survey meeting the following criteria : @xmath254 , not a known binary , not a known subdwarf , observations on two or more epochs , and total time span of observations more then 350 days .
our simulation is similar in nature to the simulations of @xcite , though we made some simplifying assumptions . using the actual times of observations of these 40 targets , as well as the actual rv error estimates for each observation
, we generated @xmath255 hypothetical surveys where each of the 40 targets is a tight binary .
for the mass ratio , @xmath125 , we used a power - law distribution with exponent @xmath256 @xcite .
we assumed that each of our ucds has a mass of @xmath257 and used a uniform distribution in @xmath258 between @xmath259 and @xmath260 au to calculate spectroscopic binary orbits with random phase , argument of periapsis , @xmath127 , and inclination .
we assumed a distribution of eccentricity that is uniform between @xmath261 and @xmath262 .
we generated synthetic data based on the binary orbits , the actual times of the nirspec observations , and adding noise based on the scaled error estimates at each epoch , @xmath79 .
since we have already adjusted our empirical error estimates so that they are a good description of the overall statistical properties of our data , we feel that a synthetic data set generated in this way is a fair representation of a potential survey .
we excluded epochs after april , 2009 since these observations were primarily for follow - up of suspected binary systems . to estimate the efficiency with which such systems would have been detected in our survey we counted the number of binary systems detected in each simulated survey with a conservative requirement that @xmath263 to qualify as a detection .
based on these simulations we estimated that our overall average efficiency in detecting systems with @xmath264 au is @xmath265 .
we found that this efficiency is relatively insensitive to the assumed mass of the primary and , since it is peaked near 1.0 , the assumed mass ratio distribution .
our survey contains 43 targets that would have been included in the sample based on the above criteria alone and assuming that none of these systems passed the magnitude cut because they are unknown binaries . within this sample we found one definite tight sb1 system ( 2m0320@xmath304 ) and one possible sb1 system ( 2m1507@xmath316 ) , though
if this system is a genuine sb1 then the separation may be larger than @xmath252 au .
the system 2m0746 + 20 was a known astrometric binary , with @xmath16au , and lsr1610@xmath30040 and lsr0602 + 39 were known subdwarfs .
based on the estimated detection efficiency , a flat prior on the binary fraction , and the detection of 1 ( possibly 2 ) tight binaries , we use the binomial distribution to make a bayesian estimate of the fraction of late - m and l dwarf systems in tight binaries ( @xmath266 confidence ) of @xmath7 ( @xmath267 ) .
while our sample is small and the number of detected tight binaries is small , our observations are consistent with the overall binary properties from @xcite and in particular with the prediction that @xmath268 of ucds are in binaries with @xmath6 au . assuming similar underlying statistical distributions to the ones we used here , @xcite combined radial velocity observations from the literature and found a relatively large number of close binaries , requiring an overall binary fraction of @xmath269 , approximately a factor of two higher than those from @xcite , @xcite , and @xcite .
while our results are consistent with the lower overall binary fraction , our current constraint does not rule out the higher value . for at least four reasons , ucds are excellent targets for planet searches
@xmath270 : the semi - amplitude of the doppler signal , @xmath112 , increases inversely with the mass of the host star ( @xmath271 ) for a fixed orbital period and planetary mass .
if the level of doppler precision achieved for f - g - k dwarfs can be achieved for ucds , then it becomes possible , in principle , to detect super - earth planets in the so called habitable zone ( hz ) , where in the absence of an atmosphere the equilibrium temperature of a planet is in the liquid water range .
@xmath272 : ucds have low luminosities compared to sun - like stars , meaning that the hz moves closer in to the host , serving to boost the doppler signal of a planet of fixed mass beyond the gain from the decrease in the mass of the primary .
@xmath273 : understanding the population of planetary companions to ucds , and how this population differs from that of planets orbiting f - g - k dwarfs , may allow astronomers to conduct important tests of theories of planet formation and migration .
a significant population of giant planets orbiting close to m and l dwarfs is not predicted by models of planet formation via core accretion ( i.e. @xcite ) , though such planets may be formed in the disk instability scenario @xcite .
@xmath274 : the ratio of the intrinsic brightness of a planet to its host at thermal infrared wavelengths is orders of magnitude larger when that host is a ucd rather than a sun - like star .
the relative proximity to the sun of the brightest ucds that we observe also means that planetary companions will have relatively large angular separations on the sky .
favorable contrast ratios and angular separations mean that planetary companions to ucds will likely be among the best targets for efforts to directly image and study the atmospheres of extrasolar planets at infrared and mid - infrared wavelengths using high contrast imaging techniques .
we ran a monte carlo simulation to estimate our ability to detect binary systems with small mass ratios ( @xmath275 ) and orbital separations @xmath264 au .
while our current rv precision precludes the detection of sub - jupiter - mass planets , we found that our survey is sensitive to giant planets and the lowest mass brown dwarfs over a wide range of orbital separations .
for this simulation we assumed a uniform distribution in @xmath258 from 0.005 to 1.0 au , circular orbits with @xmath276 , random inclination , phase , and @xmath127 , a primary mass of @xmath277 m@xmath161 and we tested a range of companion masses @xmath278 m@xmath279 .
we followed a similar procedure to that described previously in this section to generate @xmath255 realization of our survey and inserted spectroscopic orbits with random inclinations into the synthetic data and counted detections using the same @xmath263 criteria .
the results of this simulation are shown in figure [ planet ] . with no definitive detections of companions in this mass regime we are only able to place upper limits on the prevalence of giant planetary companions to ucds .
we found that for small orbital separations , similar to those of the hot jupiters found orbiting sun - like stars ( @xmath280 au ) , our survey is very sensitive to giant planets ( @xmath281 m@xmath279 ) and the least massive brown dwarfs .
based on the average detection efficiencies , @xmath282 , shown in figure [ planet ] , we estimate the following upper limits ( @xmath238 ) for the rate of planetary companions , @xmath283 , at orbital separations @xmath284 au : for 1m@xmath279 , @xmath285 , for 2m@xmath279 , @xmath286 , for 5m@xmath279 , @xmath287 , for 10m@xmath279 , @xmath288 .
it is also interesting to consider the case of companion with mass 15m@xmath279 , possibly a y dwarf , for which we find @xmath289 for @xmath290 au .
based on other observational evidence we would expect the rate of close - in giant companions to be very low .
if a system with @xmath275 and @xmath284 au can be thought of as a binary system , as opposed to a planetary system , then the mass ratio distribution , separation distribution , and overall binary fraction from @xcite would predict that the frequency of such companions would be exceedingly rare , orbiting fewer than 1 in @xmath291 ucds .
there are a number of very massive planets known to orbit at these distances from sun - like stars , including wasp-19b @xcite , corot-2b @xcite , and wasp-14b @xcite , though these massive hot jupiters are relatively rare with a rate of occurrence of @xmath292 @xcite . the analyses of @xcite and @xcite both indicate that the overall rate of occurrence of planets decreases with stellar mass , with the rate of planets orbiting m stars being down by a factor of @xmath293 compared to sun - like stars .
while there is no direct observational evidence pertaining to hot jupiters orbiting ucds , extrapolating from the observed properties of planets orbiting high mass stars indicates that the expected rate of occurrence , @xmath294 , of these companions is probably less than @xmath295 .
we report the results of a nir doppler survey designed to detect unseen companions to ultracool dwarfs .
infrared radial velocity measurements are a powerful tool for detecting ucd spectroscopic binaries and potentially even giant planets orbiting low - mass stars and brown dwarfs .
we have developed a new technique for making radial velocity measurements at infrared wavelengths using ch@xmath0 absorption features in the earth s atmosphere as a simultaneous wavelength reference .
we have used this technique to carry out a doppler survey of ucds using nirspec on the keck ii telescope .
we obtained more than 600 spectra of 59 ucds on two or more epochs .
we forward modeled our spectra using high - resolution theoretical ucd templates and the observed telluric spectrum , scaled for airmass , to measure radial velocity , rv , and the projected rotational velocity , @xmath4 .
we estimated our rv precision to be 50 m s@xmath1 for bright , slowly rotating m dwarfs and @xmath296 m s@xmath1 for slowly rotating ucds . within the framework of the photon - limited doppler precision
, we investigated different sources of noise that may limit our rv precision .
neglecting secular changes in ch@xmath0 absorption features due to winds or changes is barometric pressure , we estimated that for our typical spectra ( s / n@xmath297 ) , the telluric features themselves limit rv precision to @xmath86 m s@xmath1 .
we estimated that the overall precision of our rv measurements ( @xmath79 ) is within a factor of two of the photon limit .
there are several potential sources for this excess noise including changes in the symmetry of the nirspec lsf , changes in the ch@xmath0 absorption features themselves , episodes of high read noise in the detector , mismatch between the theoretical templates and the actual ucd spectra , and changes in the phase and amplitude of the `` fringing '' pattern seen in our nirspec spectra .
we explored avenues for mitigating these instrumental sources of rv variations , but ultimately were unable to improve the overall rv precision to the photon limit .
we identified one new spectroscopic binary , one candidate binary , and obtained rv measurements of two astrometric binaries from the literature .
the candidate spectroscopic binary , 2m1507@xmath316 , shows a long - term rv trend and the absence of any observed companion in high - resolution imaging observations may indicate that the system is a low - amplitude spectroscopic binary with a period @xmath298 d. due to the proximity of the primary to the sun , this object is an excellent target for ongoing efforts to directly image small mass ratio ucd binary systems .
we also investigated the rotation and kinematics of the ucds in our sample .
our estimates of @xmath4 are consistent with those in the literature . unlike @xcite ,
our sample contains at least four mid - l dwarfs that are rotating at @xmath299 km s@xmath1 , though we conclude that our two samples are statistically consistent . with proper motions and distance estimates from the literature
, we were able to use our rv measurements to calculate the full 3d space velocities of 55 l dwarfs and estimate the width of the distribution of the measured values of @xmath228 .
the dispersion of this velocity distribution is expected to be directly related to the age of a stellar population .
we estimated the kinematic age of our sample to be @xmath5 gyr .
based on simulations of our detection efficiency we estimated the rate of tight binaries ( @xmath6 au ) to be @xmath300 , consistent with an overall binary fraction of @xmath301 and a predicted tight binary fraction of @xmath8 given by @xcite .
finally , we simulated our ability to detect giant planetary companions in short - period orbits and concluded that a large population of giant planets ( @xmath281 m@xmath279 ) in close ( @xmath284 au ) orbits would have been detected in our survey .
specifically , we find that the rate of ocurrence of companions with @xmath302m@xmath279 and @xmath284 au is less than 62@xmath42 and that the rate of ocurrence of more massive companions with @xmath303m@xmath279 and @xmath290 au is less than 8.8@xmath42 _ acknowledgments _ we would like to thank d. saumon and m. marley for providing the library of high - resolution synthetic ucd spectra that made this work possible as well as for thoughtful comments on this manuscript .
we are grateful to the referee , a. reiners , for his careful reading of our manuscript and his many helpful suggestions for improvements .
we thank d. spiegel for several helpful discussions about statistics .
it is a pleasure to acknowledge d. latham , c. stubbs , g. torres for their guidance throughout this work .
we also thank d. finkbeiner , a. loeb , and k. stassun for helpful discussions and suggestions for improvements to this work .
we also would like to thank j. bailey for helpful discussions throughout the process of reducing and analyzing the nirspec data .
chb acknowledges financial support from the harvard origins of life initiative , nexsci , and the nsf astronomy & astrophysics postdoctoral fellowship program .
data presented herein were obtained at the w. m. keck observatory in part with telescope time allocated to the national aeronautics and space administration through the agency s scientific partnership with the california institute of technology and the university of california .
the observatory was made possible by the generous financial support of the w. m. keck foundation .
we would like to thank g. hill , j. lyke and the keck staff for their support over the course of this program .
the keck observatory was made possible by the generous financial support of the w.m .
keck foundation .
the authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of mauna kea has always had within the indigenous hawaiian community .
we are most fortunate to have the opportunity to conduct observations from this mountain .
this research has benefited from the m , l , and t dwarf compendium housed at dwarfarchives.org and maintained by c. gelino , d. kirkpatrick , and a. burgasser .
livingston , w. & wallace , l. 1991 , `` an atlas of the solar spectrum in the infrared from 1850 to 9000 1/cm '' , nso technical report , tucson : national solar observatory , national optical astronomy observatory .
lccccc gj1001b & 00 04 34.84 & @xmath340 44 05.8 & 13.11 & 11.40 & l5 + 2m0015 + 35 & 00 15 44.76 & + 35 16 02.6 & 13.88 & 12.26 & l2 + 2m0036 + 18 & 00 36 16.17 & + 18 21 10.4 & 12.47 & 11.06 & l3.5 + 2m0045 + 16 & 00 45 21.43 & + 16 34 44.6 & 13.06 & 11.37 & l2 + 2m0141 + 18 & 01 41 03.21 & + 18 04 50.2 & 13.88 & 12.49 & l1 + 2m0144@xmath307 & 01 44 35.36 & @xmath307 16 14.2 & 14.19 & 12.27 & l5 + 2m0213 + 44 & 02 13 28.80 & + 44 44 45.3 & 13.49 & 12.21 &
l1.5 + 2m0227@xmath316 & 02 27 10.36 & @xmath316 24 47.9 & 13.57 & 12.14 & l1 + 2m0228 + 25 & 02 28 11.01 & + 25 37 38.0 & 13.84 & 12.47 & l0 + 2m0235@xmath323 & 02 35 59.93 & @xmath323 31 20.5 & 12.69 & 12.19 &
l1 + 2m0251@xmath303 & 02 51 14.90 & @xmath303 52 45.9 & 13.06 & 11.66 & l3 + 2m0306@xmath336 & 03 06 11.59 & @xmath336 47 52.8 & 11.69 & 10.63 & m8 + 2m0320@xmath304 & 03 20 28.39 & @xmath304 46 35.8 & 13.26 & 12.13 & m8/l0 + 2m0355 + 11 & 03 55 23.37 & + 11 33 43.7 & 14.05 & 11.53 & l5 + 2m0500 + 03 & 05 00 21.00 & + 03 30 50.1 & 13.67 & 12.06 & l4 + 2m0523@xmath314 & 05 23 38.22 & @xmath314 03 02.2 & 13.08 & 11.64 & l2.5 + 2m0539@xmath300 & 05 39 52.00 & @xmath300 59 01.9 & 14.03 & 12.53 & l5 + 2m0543 + 64 & 05 43 18.87 & + 64 22 52.8 & 13.57 & 12.05 & l1 + lsr0602 + 39 & 06 02 30.45 & + 39 10 59.2 & 12.30 & 10.86 & l1 + 2m0632 + 83 & 06 32 06.17 & + 83 05 01.4 & 13.75 & 12.40 & l0.5 + 2m0652 + 47 & 06 52 30.73 & + 47 10 34.8 & 13.51 & 11.69 & l4.5 + 2m0700 + 31 & 07 00 36.64 & + 31 57 26.6 & 12.92 & 11.32 & l3.5 + 2m0717 + 57 & 07 17 16.26 & + 57 05 43.0 & 14.64 & 12.94 & l3 + 2m0746 + 20 & 07 46 42.56 & + 20 00 32.1 & 11.76 & 10.47 & l0.5 + 2m0828@xmath313 & 08 28 34.19 & @xmath313 09 19.8 & 12.80 & 11.30 & l2 + 2m0835@xmath308 & 08 35 42.56 & @xmath308 19 23.7 & 13.17 & 11.14 & l5 + 2m0847@xmath315 & 08 47 28.72 & @xmath315 32 37.2 & 13.51 & 12.06 & l2 + 2m0921@xmath321 & 09 21 14.10 & @xmath321 04 44.6 & 12.78 & 11.69 & l1.5 + 2m0911 + 74 & 09 11 12.97 & + 74 01 08.1 & 12.92 & 11.75 & l0 + 2m1022 + 58 & 10 22 48.21 & + 58 25 45.3 & 13.50 & 12.16 & l1 + 2m1045@xmath301 & 10 45 24.00 & @xmath301 49 57.6 & 13.16 & 11.78 & l1 + 2m1048 + 01 & 10 48 42.81 & + 01 11 58.0 & 12.92 & 11.62 & l1 + 2m1108 + 68 & 11 08 30.81 & + 68 30 16.9 & 13.12 & 11.58 & l1 + 2m1112 + 35 & 11 12 25.67 & + 35 48 13.1 & 14.58 & 12.72 & l4.5 + 2m1155@xmath337 & 11 55 39.52 & @xmath337 27 35.0 & 12.81 & 11.46 & l2 + 2m1203 + 00 & 12 03 58.12 & + 00 15 50.0 & 14.01 & 12.48 &
l3 + 2m1221 + 02 & 12 21 27.70 & + 02 57 19.8 & 13.17 & 11.95 & l0 + 2m1300 + 19 & 13 00 42.55 & + 19 12 35.4 & 12.72 & 11.62 & l1
+ 2m1305@xmath325 & 13 05 40.19 & @xmath325 41 05.9 & 13.41 & 11.75 & l2 + 2m1425@xmath336 & 14 25 27.98 & @xmath336 50 22.9 & 13.75 & 11.81 & l3 + 2m1439 + 19 & 14 39 28.36 & + 19 29 14.9 & 12.76 & 11.55 & l1 + 2m1506 + 13 & 15 06 54.41 & + 13 21 06.0 & 13.36 & 11.74 & l3 + 2m1507@xmath316 & 15 07 47.69 & @xmath316 27 38.6 & 12.83 & 11.31 & l5 + 2m1515 + 48 & 15 15 00.83 & + 48 47 41.6 & 14.11 & 12.50 & l6 + 2m1539@xmath305 & 15 39 41.89 & @xmath305 20 42.8 & 13.92 & 12.57 & l4 + 2m1552 + 29 & 15 52 59.06 & + 29 48 48.5 & 13.48 & 12.02 & l0 + 2m1555@xmath309 & 15 55 15.73 & @xmath309 56 05.5 & 12.56 & 11.44 & l1 + lsr1610@xmath30040 & 16 10 29.00 & @xmath300 40 53.0 & 12.91 & 12.02 & sdm7 + 2m1645@xmath313 & 16 45 22.11 & @xmath313 19 51.6 & 12.45 & 11.15 & l1.5 + 2m1658 + 70 & 16 58 03.80 & + 70 27 01.5 & 13.29 & 11.91 & l1 + 2m1705@xmath305 & 17 05 48.34 & @xmath305 16 46.2 & 13.31 & 12.03 &
+ 2m1731 + 27 & 17 31 29.74 & + 27 21 23.3 & 12.09 & 10.91 & l0 + 2m1807 + 50 & 18 07 15.93 & + 50 15 31.6 & 12.93 & 11.60 & l1.5 + 2m1821 + 14 & 18 21 28.15 & + 14 14 01.0 & 13.43 & 11.65 & l4.5 + 2m1854 + 84 & 18 54 45.97 & + 84 29 47.1 & 11.54 & 11.35 &
+ 2m2036 + 10 & 20 36 03.16 & + 10 51 29.5 & 13.95 & 12.45 & l3 + 2m2057@xmath302 & 20 57 54.09 & @xmath302 52 30.2 & 13.12 & 11.72 & l1.5 + 2m2104@xmath310 & 21 04 14.91 & @xmath310 37 36.9 & 13.84 & 12.37 &
l2.5 + 2m2224@xmath301 & 22 24 43.81 & @xmath301 58 52.1 & 14.07 & 12.02 & l4.5 + gj1001b & 4 & 398 & 1600 & 24.80@xmath73 0.40 & 32.84@xmath73 0.17 & 0.30 & 0.47 + 2m0015 + 35 & 5 & 406 & 2200 & 10.23@xmath73 2.55 & @xmath337.35@xmath73 0.16 & 0.37 & 0.17 + 2m0036 + 18 & 6 & 351 & 2000 & 35.12@xmath73 0.57 & 19.02@xmath73 0.15 & 0.26 & 0.05 + 2m0045 + 16 & 6 & 351 & 2100 & 32.82@xmath73 0.17 & 3.29@xmath73 0.17 & 0.40 & 0.05 + 2m0141 + 18 & 4 & 822 & 2200 & @xmath3049.0 & 24.65@xmath73 0.13 & 0.39 & 0.76 + 2m0144@xmath307 & 5 & 821 & 1600 & 23.03@xmath73 0.45 & @xmath32.55@xmath73 0.10 & 0.36 & 0.97 + 2m0213 + 44 & 5 & 823 & 2200 & 12.89@xmath73 2.34 & @xmath323.47@xmath73 0.11 & 0.20 & 0.52 + 2m0227@xmath316 & 2 & 431 & 2100 & @xmath3049.0 & 48.58@xmath73 0.15 & 0.25 & 0.49 + 2m0228 + 25 & 5 & 406 & 2100 & 31.19@xmath73 0.81 & 23.07@xmath73 0.21 & 0.29 & 0.13 + 2m0235@xmath323 & 6 & 823 & 2200 & 15.85@xmath73 0.53 & 15.38@xmath73 0.11 & 0.26 & 0.71 + 2m0251@xmath303 & 3 & 351 & 2100 & 21.76@xmath73 0.38 & 1.26@xmath73 0.13 & 0.31 & 0.80 + 2m0306@xmath336 & 2 & 358 & 1900 & 21.44@xmath73 0.26 & 11.44@xmath73 0.19 & 0.18 & 0.43 + 2m0320@xmath304 & 16 & 1180 & 1900 & 16.71@xmath73 0.53 & 3.13@xmath73 0.06 & 5.32 & @xmath3050.99 + 2m0355 + 11 & 2 & 322 & 1900 & 12.31@xmath73 0.15 & 11.92@xmath73 0.22 & 0.45 & 0.50 + 2m0500 + 03 & 2 & 322 & 1600 & 9.65@xmath73 0.36 & 15.94@xmath73 0.16 & 0.09 & 0.26 + 2m0523@xmath314 & 5 & 821 & 2100 & 15.98@xmath73 0.31 & 12.21@xmath73 0.09 & 0.19 & 0.70 + 2m0539@xmath300 & 4 & 614 & 1600 & 32.30@xmath73 0.75 & 13.91@xmath73 0.15 & 0.38 & 0.83 + 2m0543 + 64 & 2 & 57 & 2200 & 20.06@xmath73 0.52 & 18.64@xmath73 0.23 & 0.11 & 0.26 + lsr0602 + 39 & 10 & 1029 & 2100 & 12.51@xmath73 0.22 & 7.94@xmath73 0.05 & 0.24 & @xmath3050.99 + 2m0632 + 83 & 2 & 96 & 1900 & 9.90@xmath73 0.40 & @xmath326.00@xmath73 0.24 & 0.06 & 0.11 + 2m0652 + 47 & 10 & 1030 & 1600 & 30.08@xmath73 1.76 & @xmath37.03@xmath73 0.07 & 0.21 & 0.33 + 2m0700 + 31 & 6 & 670 & 2100 & 29.91@xmath73 0.27 & @xmath342.42@xmath73 0.09 & 0.25 & 0.77 + 2m0717 + 57 & 2 & 1 & 2100 & 13.93@xmath73 0.55 & @xmath316.32@xmath73 0.17 & 0.19 & 0.54 + 2m0746 + 20 & 10 & 1030 & 2100 & 32.72@xmath73 0.56 & 52.37@xmath73 0.06 & 0.59 & @xmath3050.99 + 2m0828@xmath313 & 5 & 357 & 2300 & 29.13@xmath73 5.00 & 25.85@xmath73 0.08 & 0.28 & 0.93 + 2m0835@xmath308 & 8 & 1028 & 2200 & 14.18@xmath73 0.43 & 29.89@xmath73 0.06 & 0.15 & 0.52 + 2m0847@xmath315 & 5 & 999 & 2200 & 23.29@xmath73 0.32 & 2.02@xmath73 0.10 & 0.08 & 0.03 + 2m0911 + 74 & 2 & 362 & 2000 & 12.18@xmath73 0.59 & @xmath34.06@xmath73 0.15 & 0.28 & 0.79 + 2m0921@xmath321 & 3 & 680 & 2000 & 11.95@xmath73 0.49 & 80.53@xmath73 0.11 & 0.05 & 0.04 + 2m1022 + 58 & 3 & 682 & 2200 & 11.81@xmath73 0.21 & 19.29@xmath73 0.11 & 0.10 & 0.08 + 2m1045@xmath301 & 4 & 677 & 2200 & @xmath3049.0 & 6.31@xmath73 0.10 & 0.22 & 0.77 + 2m1048 + 01 & 7 & 1030 & 2100 & 10.36@xmath73 0.25 & 24.25@xmath73 0.06 & 0.22 & 0.91 + 2m1108 + 68 & 5 & 999 & 2100 & 26.03@xmath73 0.29 & @xmath39.84@xmath73 0.11 & 0.29 & 0.49 + 2m1112 + 35 & 6 & 2249 & 2100 & 28.65@xmath73 1.01 & @xmath34.28@xmath73 0.13 & 0.39 & 0.33 + 2m1155@xmath337 & 2 & 264 & 2200 & 13.61@xmath73 0.31 & 45.57@xmath73 0.11 & 0.27 & 0.73 + 2m1203 + 00 & 3 & 678 & 1600 & 31.33@xmath73 0.55 & @xmath30.22@xmath73 0.16 & 0.57 & 0.88 + 2m1221 + 02 & 3 & 681 & 2000 & 23.82@xmath73 0.42 & @xmath38.79@xmath73 0.14 & 0.32 & 0.49 + 2m1300 + 19 & 5 & 1040 & 2200 & 12.83@xmath73 2.10 & @xmath317.60@xmath73 0.12 & 0.22 & 0.28 + 2m1305@xmath325 & 2 & 29 & 2100 & 68.88@xmath73 2.60 & 6.37@xmath73 0.35 & 0.05 & 0.06 + 2m1425@xmath336 & 2 & 303 & 2000 & 32.37@xmath73 0.66 & 5.37@xmath73 0.25 & 0.25 & 0.38 + 2m1439 + 19 & 5 & 1069 & 2200 & 11.10@xmath73 0.24 & @xmath326.74@xmath73 0.09 & 0.17 & 0.43 + 2m1506 + 13 & 3 & 853 & 2200 & 11.39@xmath73 0.94 & @xmath30.68@xmath73 0.11 & 0.12 & 0.28 + 2m1507@xmath316 & 9 & 2249 & 1600 & 21.27@xmath73 1.86 & @xmath339.85@xmath73 0.05 & 0.27 & @xmath3050.99 + 2m1515 + 48 & 4 & 707 & 1600 & 12.52@xmath73 1.65 & @xmath329.97@xmath73 0.11 & 0.14 & 0.13 + 2m1539@xmath305 & 3 & 29 & 1800 & 40.09@xmath73 0.76 & 27.33@xmath73 0.24 & 0.48 & 0.52 + 2m1552 + 29 & 4 & 1237 & 2000 & 18.91@xmath73 0.57 & @xmath318.43@xmath73 0.11 & 0.03 & 0.01 + 2m1555@xmath309 & 5 & 1233 & 2200 & @xmath3049.0 & 14.84@xmath73 0.10 & 0.25 & 0.46 + lsr1610@xmath30040 & 4 & 1541 & 1900 & 16.84@xmath73 3.11 & @xmath397.89@xmath73 0.21 & 5.41 & @xmath3050.99 + 2m1645@xmath313 & 6 & 1234 & 2200 & 9.31@xmath73 0.27 & 26.58@xmath73 0.06 & 0.15 & 0.51 + 2m1658 + 70 & 5 & 2041 & 2200 & 12.26@xmath73 0.76 & @xmath325.60@xmath73 0.12 & 0.17 & 0.20 + 2m1705@xmath305 & 3 & 425 & 2200 & 27.67@xmath73 0.32 & 12.19@xmath73 0.11 & 0.11 & 0.18 + 2m1731 + 27 & 3 & 526 & 2000 & 11.62@xmath73 0.15 & @xmath329.76@xmath73 0.11 & 0.34 & 0.92 + 2m1807 + 50 & 4 & 528 & 2100 & 69.88@xmath73 2.48 & @xmath30.36@xmath73 0.46 & 1.14 & 0.45 + 2m1821 + 14 & 2 & 162 & 2200 & 28.85@xmath73 0.16 & 9.78@xmath73 0.16 & 0.14 & 0.43 + 2m1854 + 84 & 3 & 351 & 2000 & 10.23@xmath73 0.13 & @xmath32.93@xmath73 0.17 & 0.10 & 0.10 + 2m2036 + 10 & 2 & 146 & 2100 & 67.11@xmath73 1.52 & 19.66@xmath73 0.47 & 1.59 & 0.86 + 2m2057@xmath302 & 3 & 351 & 2100 & 60.56@xmath73 0.37 & @xmath324.68@xmath73 0.43 & 0.61 & 0.48 + 2m2104@xmath310 & 6 & 748 & 2200 & 23.44@xmath73 0.23 & @xmath321.09@xmath73 0.12 & 0.39 & 0.58 + 2m2224@xmath301 & 8 & 750 & 1600 & 25.49@xmath73 0.41 & @xmath337.55@xmath73 0.09 & 0.19 & 0.09 + lcc 52921.102 & 6.148 & 0.378 + 52922.113 & 6.550 & 0.294 + 52957.027 & 4.392 & 0.327 + 53272.125 & @xmath36.443 & 0.234 + 53273.086 & @xmath36.461 & 0.235 + 53328.828 & @xmath34.113 & 0.225 + 53421.719 & 6.274 & 0.194 + 53669.887 & 5.905 & 0.291 + 53670.879 & 6.363 & 0.191 + 53686.859 & 5.453 & 0.178 + 53742.809 & @xmath32.912 & 0.331 + 53743.856 & @xmath33.140 & 0.258 + 53744.840 & @xmath33.378 & 0.407 + 54023.969 & @xmath37.276 & 0.216 + 54100.746 & 1.134 & 0.295 + 54101.754 & 1.398 & 0.673 + period ( day ) & 246.9 @xmath306 + e & 0.067@xmath307 + @xmath127 ( @xmath308 ) & 167.2@xmath309 + @xmath60 ( mjd ) & 53529.9@xmath310 + @xmath112 ( km s@xmath1 ) & [email protected] + @xmath126 ( km s@xmath1 ) & 0.154@xmath311 + @xmath312 ( @xmath313 ) & 0.2032@xmath314 + @xmath315 ( au ) & [email protected] + .
period ( day ; fixed ) & 607.1@xmath316 + e ( fixed ) & 0.444@xmath317 + @xmath145 ( @xmath308 ; fixed ) & 83.2@xmath318 + @xmath127 ( @xmath308 ; fixed ) & 151.4@xmath319 + @xmath60 ( mjd ) & 53680.2 @xmath320 + @xmath112 ( km s@xmath1 ) & 8.02@xmath321 + @xmath126 ( km s@xmath1 ) & @xmath399.49@xmath322 + @xmath323 ( @xmath313 ) & 0.025@xmath324 + @xmath151 ( au ) & 0.404@xmath325 ccc 0.20 & 0.144 & 0.138 + 0.15 & 0.124 & 0.150 + 0.10 & 0.10 & 0.166 + 0.095 & 0.098 & 0.168 + 0.090 & 0.096 & 0.170 + 0.085 & 0.093 & 0.172 + 0.08 & 0.900 & 0.175 + 0.075 & 0.087 & 0.177 + 0.07 & 0.085 & 0.181 + lcc 52714.066 & @xmath339.536 & 0.120 + 52715.105 & @xmath339.561 & 0.155 + 52744.043 & @xmath339.333 & 0.207 + 53072.102 & @xmath339.527 & 0.263 + 53421.086 & @xmath339.773 & 0.250 + 53597.730 & @xmath339.962 & 0.161 + 53948.742 & @xmath339.906 & 0.304 + 54930.055 & @xmath339.707 & 0.270 + 54962.895 & @xmath339.979 & 0.141 + 54963.895 & @xmath340.068 & 0.080 + gj1001b & 1.37@xmath73 0.42 & @xmath3109.16@xmath73 5.55 & @xmath320.03@xmath73 0.62 & 110.99@xmath73 5.61 + 2m0015 + 35 & 13.03@xmath73 2.02 & @xmath342.88@xmath73 1.76 & @xmath36.53@xmath73 2.54 & 45.29@xmath73 3.69 + 2m0036 + 18 & @xmath342.15@xmath73 0.41 & @xmath35.80@xmath73 0.22 & @xmath311.59@xmath73 0.09 & 44.10@xmath73 0.47 + 2m0045 + 16 & @xmath322.96@xmath73 1.79 & @xmath313.41@xmath73 1.30 & @xmath33.98@xmath73 0.59 & 26.88@xmath73 2.29 + 2m0141 + 18 & @xmath348.92@xmath73 3.08 & @xmath321.11@xmath73 2.97 & @xmath310.94@xmath73 1.08 & 54.39@xmath73 4.41 + 2m0144@xmath307 & @xmath320.82@xmath73 2.62 & @xmath346.41@xmath73 4.43 & 3.88@xmath73 0.84 & 51.01@xmath73 5.22 + 2m0213 + 44 & 19.54@xmath73 5.37 & @xmath317.52@xmath73 5.40 & @xmath38.81@xmath73 5.69 & 27.68@xmath73 9.51 + 2m0227@xmath316 & @xmath336.24@xmath73 1.55 & @xmath361.75@xmath73 3.01 & @xmath331.17@xmath73 1.21 & 78.09@xmath73 3.60 + 2m0228 + 25 & @xmath339.56@xmath73 2.87 & @xmath314.08@xmath73 3.28 & @xmath30.38@xmath73 2.15 & 41.99@xmath73 4.86 + 2m0235@xmath323 & @xmath312.45@xmath73 0.20 & @xmath38.45@xmath73 0.16 & @xmath310.38@xmath73 0.16 & 18.28@xmath73 0.30 + 2m0251@xmath303 & 15.68@xmath73 1.58 & @[email protected] & @xmath314.14@xmath73 1.26 & [email protected] + 2m0320@xmath304 & [email protected] & @xmath326.46@xmath73 5.39 & @xmath344.23@xmath73 8.68 & [email protected] + 2m0352 + 02 & @xmath355.97@xmath73 2.22 & 7.41@xmath73 2.53 & 12.77@xmath73 2.73 & 57.89@xmath73 4.34 + 2m0355 + 11 & @xmath36.29@xmath73 1.06 & @xmath322.19@xmath73 2.91 & @xmath314.79@xmath73 1.32 & 27.40@xmath73 3.37 + 2m0500 + 03 & @xmath34.82@xmath73 1.34 & @xmath320.41@xmath73 1.79 & @xmath316.43@xmath73 1.48 & 26.64@xmath73 2.68 + 2m0523@xmath314 & @xmath316.27@xmath73 0.93 & @xmath33.26@xmath73 0.95 & 3.30@xmath73 1.17 & 16.92@xmath73 1.77 + 2m0539@xmath300 & @xmath321.86@xmath73 0.37 & 3.31@xmath73 0.32 & 13.84@xmath73 0.55 & 26.09@xmath73 0.74 + lsr0602 + 39 & @xmath311.90@xmath73 0.38 & @xmath326.51@xmath73 2.59 & @xmath32.47@xmath73 0.74 & 29.16@xmath73 2.72 + 2m0652 + 47 & 7.38@xmath73 0.93 & 5.97@xmath73 2.65 & @xmath34.08@xmath73 2.16 & 10.34@xmath73 3.55 + 2m0700 + 31 & 42.13@xmath73 0.15 & @xmath328.97@xmath73 0.95 & @xmath315.62@xmath73 0.25 & 53.46@xmath73 1.00 + 2m0717 + 57 & 13.88@xmath73 1.17 & @xmath32.03@xmath73 1.34 & @xmath38.07@xmath73 2.77 & 16.19@xmath73 3.29 + 2m0746 + 20 & @xmath355.63@xmath73 0.14 & @xmath315.04@xmath73 0.07 & @xmath31.74@xmath73 0.09 & 57.65@xmath73 0.19 + 2m0828@xmath313 & @xmath338.71@xmath73 3.50 & @xmath313.49@xmath73 1.10 & @xmath320.68@xmath73 3.91 & 45.91@xmath73 5.36 + 2m0835@xmath308 & @xmath333.22@xmath73 2.48 & @xmath314.77@xmath73 1.33 & 0.89@xmath73 1.65 & 36.37@xmath73 3.27 + 2m0847@xmath315 & 15.84@xmath73 1.28 & @xmath310.68@xmath73 0.74 & 1.79@xmath73 1.01 & 19.19@xmath73 1.79 + 2m0921@xmath321 & 19.43@xmath73 3.85 & @xmath394.59@xmath73 2.04 & 5.77@xmath73 2.12 & 96.74@xmath73 4.84 + 2m0953@xmath310 & @xmath34.72@xmath73 1.83 & @xmath321.15@xmath73 1.47 & 2.14@xmath73 1.80 & 21.77@xmath73 2.96 + 2m1022 + 58 & @[email protected] & 60.85@xmath73 9.29 & @[email protected] & [email protected] + 2m1045@xmath301 & @xmath335.71@xmath73 2.41 & @xmath314.22@xmath73 1.00 & @xmath312.83@xmath73 1.33 & 40.52@xmath73 2.93 + 2m1048 + 01 & @xmath324.91@xmath73 1.57 & @xmath334.50@xmath73 1.47 & @xmath31.43@xmath73 1.47 & 42.58@xmath73 2.61 + 2m1051 + 56 & @xmath315.81@xmath73 4.00 & @xmath331.47@xmath73 2.39 & @xmath316.95@xmath73 1.99 & 39.09@xmath73 5.06 + 2m1108 + 68 & @xmath341.59@xmath73 8.42 & @xmath336.59@xmath73 4.47 & @xmath317.93@xmath73 4.02 & [email protected] + 2m1112 + 35 & @xmath320.75@xmath73 0.45 & @xmath325.17@xmath73 0.50 & @xmath313.83@xmath73 0.31 & 35.43@xmath73 0.74 + 2m1155@xmath337 & 35.42@xmath73 2.09 & @xmath350.55@xmath73 1.19 & @xmath322.97@xmath73 3.41 & 65.86@xmath73 4.17 + 2m1203 + 00 & @xmath383.82@xmath73 8.69 & @xmath367.49@xmath73 7.03 & @xmath329.92@xmath73 3.11 & [email protected] + 2m1221 + 02 & 51.86@xmath73 9.23 & @xmath323.29@xmath73 5.19 & @xmath327.25@xmath73 3.49 & [email protected] + 2m1300 + 19 & @xmath33.87@xmath73 1.22 & @xmath398.51@xmath73 7.00 & @xmath326.40@xmath73 0.67 & 102.06@xmath73 7.14 + 2m1305@xmath325 & @xmath320.27@xmath73 0.86 & @xmath319.39@xmath73 0.67 & 6.24@xmath73 0.33 & 28.74@xmath73 1.14 + 2m1425@xmath336 & @xmath35.05@xmath73 1.09 & @xmath322.47@xmath73 2.23 & @xmath310.26@xmath73 1.50 & 25.22@xmath73 2.90 + 2m1439 + 19 & @xmath385.11@xmath73 0.53 & @xmath342.92@xmath73 0.28 & 17.75@xmath73 0.31 & 96.96@xmath73 0.68 + 2m1506 + 13 & @xmath341.64@xmath73 3.22 & @xmath348.84@xmath73 3.82 & 36.85@xmath73 2.92 & 74.01@xmath73 5.79 + 2m1507 - 16 & @[email protected] & @[email protected] & @[email protected] & [email protected] + 2m1515 + 48 & @xmath3107.23@xmath73 9.50 & @xmath330.47@xmath73 1.63 & @xmath32.76@xmath73 2.11 & 111.51@xmath73 9.86 + 2m1539@xmath305 & 37.58@xmath73 1.20 & 35.00@xmath73 2.43 & @xmath34.76@xmath73 1.62 & 51.58@xmath73 3.16 + 2m1552 + 29 & @xmath311.09@xmath73 1.80 & @xmath322.92@xmath73 1.96 & @xmath33.75@xmath73 1.54 & 25.74@xmath73 3.08 + 2m1555@xmath309 & 52.11@xmath73 3.08 & 3.19@xmath73 1.25 & @xmath357.00@xmath73 5.03 & 77.29@xmath73 6.03 + lsr1610@xmath30040 & @xmath332.11@xmath73 0.82 & @xmath3232.9@xmath73 1.7 & @xmath362.75@xmath73 0.51 & [email protected] + 2m1645@xmath313 & 33.00@xmath73 0.81 & @xmath346.83@xmath73 4.46 & @xmath30.08@xmath73 1.36 & 57.28@xmath73 4.74 + 2m1658 + 70 & 24.56@xmath73 0.23 & @xmath342.29@xmath73 0.29 & 22.43@xmath73 0.45 & 53.81@xmath73 0.59 + 2m1705@xmath305 & 14.25@xmath73 0.53 & 2.95@xmath73 0.88 & @xmath33.80@xmath73 0.98 & 15.05@xmath73 1.42 + 2m1731 + 27 & @xmath35.28@xmath73 1.35 & @xmath329.71@xmath73 1.25 & @xmath313.28@xmath73 1.14 & 32.97@xmath73 2.16 + 2m1807 + 50 & 7.46@xmath73 1.41 & @xmath30.67@xmath73 1.12 & @xmath35.41@xmath73 1.88 & 9.24@xmath73 2.61 + 2m2036 + 10 & 24.26@xmath73 2.30 & 4.73@xmath73 1.75 & @xmath35.27@xmath73 1.68 & 25.27@xmath73 3.34 + 2m2104@xmath310 & @xmath338.79@xmath73 3.43 & @xmath329.37@xmath73 2.65 & @xmath333.36@xmath73 5.82 & 58.99@xmath73 7.26 + 2m2224@xmath301 & @xmath39.62@xmath73 0.11 & @xmath363.97@xmath73 0.39 & @xmath36.01@xmath73 0.34 & 64.97@xmath73 0.52 + gj1001b & [email protected] & @[email protected] & 24.80@xmath73 0.40 + 2m0227@xmath316 & 78.09@xmath326 & @xmath361.75@xmath327 & @xmath328 + 2m0251@xmath303 & [email protected] & @xmath3120.09@xmath329 & 21.76@xmath73 0.38 + 2m0921@xmath321 & [email protected] & @xmath394.59@xmath330 & 11.95@xmath73 0.49 + 2m1022 + 58 & [email protected] & 60.85@xmath331 & 11.81@xmath73 0.21 + 2m1203 + 00 & [email protected] & @xmath367.49@xmath332 & 31.33@xmath73 0.55 + 2m1300 + 19 & [email protected] & @xmath398.51@xmath333 & 12.83@xmath73 2.10 + 2m1439 + 19 & [email protected] & @xmath342.92@xmath334 & 11.10@xmath73 0.24 + 2m1515 + 48 & [email protected] & @xmath330.47@xmath335 & 12.52@xmath73 1.65 + lsr1610@xmath30040 & [email protected] & @xmath3232.96@xmath336 & 16.84@xmath73 3.11 + 2m2224@xmath301 & 64.97@xmath306 & @xmath363.97@xmath337 & 25.49@xmath322 + | we report the results of an infrared doppler survey designed to detect brown dwarf and giant planetary companions to a magnitude - limited sample of ultracool dwarfs . using the nirspec spectrograph on the keck ii telescope
, we obtained approximately 600 radial velocity measurements over a period of six years for a sample of 59 late - m and l dwarfs spanning spectral types m8/l0 to l6 .
a subsample of 46 of our targets have been observed on three or more epochs .
we rely on telluric ch@xmath0 absorption features in the earth s atmosphere as a simultaneous wavelength reference and exploit the rich set of co absorption features found in the k - band spectra of cool stars and brown dwarfs to measure radial velocities and projected rotational velocities . for a bright , slowly rotating m dwarf standard we demonstrate a radial velocity precision of 50 m s@xmath1 , and for slowly rotating l dwarfs we achieve a typical radial velocity precision of approximately 200 m s@xmath1 .
this precision is sufficient for the detection of close - in giant planetary companions to mid - l dwarfs as well as more equal mass spectroscopic binary systems with small separations ( @xmath2 au ) .
we present an orbital solution for the subdwarf binary lsr1610@xmath30040 as well as an improved solution for the m / t binary 2m0320@xmath304 .
we compare the distribution of our observed values for the projected rotational velocities , @xmath4 , to those in the literature and find that our sample contains examples of slowly rotating mid - l dwarfs , which have not been seen in other surveys .
we also combine our radial velocity measurements with distance estimates and proper motions from the literature to estimate the dispersion of the space velocities of the objects in our sample . using a kinematic age estimate
we conclude that our ucds have an age of @xmath5 gyr , similar to that of nearby sun - like stars .
we simulate the efficiency with which we detect spectroscopic binaries and find that the rate of tight ( @xmath6 au ) binaries in our sample is @xmath7 , consistent with recent estimates in the literature of a tight binary fraction of @xmath8 . |
nanostructures and nanostructured materials offer the possibility to tune heat transport properties over an exceptionally wide range .
for example in carbon based materials it is possible to obtain variations of the thermal transport coefficients over three orders of magnitude : graphene and suspended carbon nanotubes are possibly the most efficient heat conductors @xcite , whereas nanotube pellets and graphene nanoribbons with disordered edges are predicted to have thermal insulating properties @xcite .
similarly , nanostructuring may turn silicon and sige alloys into efficient thermoelectric materials , by significantly reducing the thermal conductivity ( @xmath0 ) as in the case of nanowires @xcite ( sinw ) , sige nanocomposites @xcite , superlattices @xcite , and nanoporous silicon @xcite .
further improvement in designing materials and nano - devices with controlled thermal transport properties stems from a deeper theoretical understanding of phonon transport . following landauer and bttiker s works @xcite , atomistic green s function ( gf )
formalism has become the reference method to study coherent electronic transport @xcite .
the gf approach has been transferred successfully to compute thermal transport in nanostructures @xcite , and it is the optimal framework to investigate elastic phonon scattering from impurities , defects , disorder or interfaces , i.e. in all those cases where anharmonic phonon - phonon scattering can be deemed of secondary importance @xcite .
an atomistic gf method including phonon - phonon scattering has also been developed and applied to small model systems @xcite , however one can in general safely assume elastic scattering when a finite nanoscale system between two reservoirs is considered .
this is generally the case for molecular junctions , contacts and grain boundaries .
special care must be taken in testing this assumption when one wants to extrapolate finite size calculations to extended materials , where long wavelength phonons do not get scattered by nanoscale impurities and contribute a significant amount to the total thermal conductivity . in spite of significant insight achieved in these studies based on the gf formalism
, it remains a formidable task to perform atomistic simulations of nanostructures with characteristic sizes of several tens of nanometers , as it would be needed to bridge the gap between theory and experiment . because of matrix inversion operations , even the recursive implementation of the gf method , which permits us to deal with systems extending for several micrometers in the direction of heat propagation , imposes severe size limitations in the orthogonal plane . in terms of sinw
, this means that one is limited to diameters that do not exceed few nanometers .
similar limitations hamper the predictive power of approaches based on molecular dynamics , so far restrained to the study of thin wires @xcite . here
we outline a formalism for phonon transport based on the scattering - matrix approach @xcite , which circumvents the matrix inversion problem by substituting eigenvalue equations with local kernel search and intersections . after deriving a generalized scattering - matrix approach for phonon propagation
, we illustrate the numerically stable and efficiently parallelizable kernel method .
for example , we apply the scattering formalism to compute the contact thermal resistance between bulk silicon and sinws with diameters up to 14 nm .
the scattering - matrix approach was formulated to solve quantum electronic transmission problems @xcite , and found its natural application for the simulation of scanning tunneling microscopy images @xcite and of molecular electronic devices via the so called _ elastic scattering quantum chemistry _ ( esqc ) method @xcite . here
we reformulate the theory in terms of phonon transport .
we consider a phonon wave packet , represented by a weight - normalized displacement field @xmath1 , traveling through an open system made of semi - infinite reservoirs connected by an arbitrary structure ( defect ) .
our goal is to determine the thermal energy exchanged between the reservoirs through the defect in stationary non - equilibrium conditions , i.e. when the reservoirs are kept at different temperatures . in the harmonic approximation ,
the equation of motion for the displacement field @xmath2 is @xmath3 , where @xmath4 is the dynamical matrix .
the real - valued state @xmath1 can be decomposed in terms of the complex valued eigenstates @xmath5 of @xmath4 .
given the state @xmath6 and its eigen - decomposition coefficients @xmath7 , the time propagation of @xmath1 is : @xmath8 d\omega \ .
\label{eq_eigendecomposition_ph}\ ] ] let @xmath9 be the projector associated with the degrees of freedom of an arbitrary part p of the system . to get the energy exchanged between p and the rest of the system , one can balance the time derivatives of the work from p to the whole system and vice versa , thus obtaining : @xmath10|u(t)\rangle\ .
\label{eq_e_var}\ ] ] the energy of p in stationary conditions ( @xmath11 ) is found by integrating [ eq_e_var ] to the infinite time limit .
substituting @xmath1 with its eigen - decomposition in [ eq_eigendecomposition_ph ] in the integral leads to : @xmath12|v(\omega)\rangle d\omega\ , .
\label{infinite_time_limit_2}\ ] ] all information concerning the initial state lies in the weights @xmath7 , which can be taken as the statistical distribution of the states @xmath13 when simulating a system at finite temperature . in the stationary non - equilibrium case ,
those weights refer to the rate of phonons emitted from the reservoirs ( i.e. 1d phonon gas obeying bose - einstein statistics ) : @xmath14 where @xmath15 is the bose - einstein distribution function at the reservoir temperature @xmath16 . in order to evaluate [ infinite_time_limit_2 ] , the eigensolutions @xmath17 of the open system have to be expressed in terms of a convenient basis made of a single phonon mode @xmath18 coming from a reservoir @xmath19 into the defect , and the set of phonon modes @xmath20 coming out of the defect toward the reservoirs : @xmath21 where both defect displacements and reservoir surface states at the interfaces are included in @xmath22 .
the scattering tensor @xmath23 maps the incoming phonons @xmath24 onto the outgoing phonons @xmath25 .
as the energy carried by any incoming or outgoing phonon with frequency @xmath26 is quantized as @xmath27 , [ infinite_time_limit_2 ] provides the following normalization and orthogonality conditions : @xmath28|\psi_{j\in a}^{in}(\omega)\rangle = -\frac{i\hbar}{2\pi}\cdot \delta_{ij}\\ & \phantom{\big [ } \langle \psi_{i\in a}^{out}(\omega)|[\mathbf{p}_{a},\mathbf{d}]|\psi_{j\in a}^{out}(\omega)\rangle = \phantom{-}\frac{i\hbar}{2\pi}\cdot \delta_{ij}\\ & \phantom{\big [ } \langle \psi_{i\in a}^{in}(\omega)|[\mathbf{p}_{a},\mathbf{d}]|\psi_{j\in a}^{out}(\omega)\rangle = \phantom{-}0 , \end{split } \label{phonon_norm}\ ] ] where @xmath29 denotes the projector on reservoir @xmath19 . combining the stationary non - equilibrium weights of [ eq_weight ] with [ infinite_time_limit_2 ] , and observing the conditions of [ phonon_norm ] ,
one obtains the stationary energy transfer between reservoirs @xmath19 and @xmath30 : @xmath31d\omega .
\label{infinite_time_limit_scattering}\ ] ] once @xmath23 is obtained by computing the eigenstates @xmath17 , the energy flux between two reservoirs @xmath32 is determined using the transmission coefficient @xmath33 .
the corresponding thermal conductance is given by the landauer formula as the limit of [ infinite_time_limit_scattering ] when @xmath34 : @xmath35
the first step to compute the eigenstates in [ basis1 ] is to rewrite the eigenvalue problem as a null - space search problem : @xmath36 it is then possible to consider a partition @xmath37 of the system , and to solve locally the auxiliary equations @xmath38 the solutions of the eigenvalue problem are given by the intersection of the resulting invariant subspaces : @xmath39 typically , the partition is a set of projectors on each reservoir , completed by a set of projectors on the defect . the auxiliary equations ( [ auxiliary ] ) for the defect are solved with a qr decomposition method , which is stable and numerically efficient .
the reservoirs are treated in a separate way : as in the propagator method @xcite , every reservoir is partitioned into periodic slices @xmath40 of dimension @xmath41 such that only nearest neighboring slices interact ( see [ figscheme ] ) .
however , instead of formulating a spatial propagator , we first compute the @xmath42 non - trivial solutions of [ auxiliary ] for the second slice @xmath43 of the reservoir : @xmath44 the periodic solutions are then reconstructed by solving the @xmath45 generalized eigen - problem : @xmath46\!\cdot\ ! \left[\begin{array}{c
} c_{1}\\ \vdots\\ c_{2n}\\ \end{array}\right ] = \beta \left[\begin{array}{c } v^{1}_{s2 } \dots v^{2n}_{s2}\\ v^{1}_{s3 } \dots v^{2n}_{s3}\\ \end{array}\right]\!\cdot\ ! \left[\begin{array}{c }
c_{1}\\ \vdots\\ c_{2n}\\ \end{array}\right ] .\ ] ] as every slice of the reservoir except @xmath47 is equivalent to @xmath43 , the periodic solutions hold for the entire reservoir , except for @xmath47 which is treated explicitly as part of the defect .
the intersection of the periodic solutions leads to phonon modes @xmath48 ( @xmath49=1 ) , and surfaces states ( @xmath50 ) .
after intersecting the reservoir and the defect solutions , we extract a basis @xmath51 spanning only surface states localized at the defect interface ( i.e. with @xmath52 ) : @xmath53 the scattering tensor is then computed by applying the @xmath54 transform to the @xmath51 set , providing the set of eigenstates @xmath55 defined in [ basis1 ] , so that : @xmath56 . in the presence of short range interactions ,
parts can be defined to be as small as the interaction range , so that only neighboring parts interact .
such an implementation allows efficient parallelization , in the same fashion as domain decomposition in molecular dynamics codes .
the auxiliary equations are solved locally in parallel before their intersection according to a binomial tree .
furthermore , a reciprocal space sampling technique allows an efficient treatment of the periodic reservoirs solutions . within this framework ,
the main limitation of the approach is the treatment of non - periodic 1d reservoirs , which requires the full diagonalisation of a matrix , which scales as the square of the surface of the contact .
[ [ thermal - conductance - of - bulk - siliconsilicon - nanowire - contacts . ] ] thermal conductance of bulk silicon / silicon nanowire contacts .
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + we apply the scattering matrix approach to compute the contact thermal resistance of a bulk - sinw interface .
interface resistance plays an essential role in determining the thermal transport performance of nanostructured materials and nanoscale devices .
in addition , evaluating the thermoelectric performances of nanostructures such as sinw , it is indispensable to be able to resolve the contact thermal resistance from the intrinsic resistance .
a few special cases , such as grain boundaries in silicon , crystalline / amorphous interfaces and silicon / germanium junctions , have previously been addressed using molecular dynamics and real - space kubo - greenwood formalism @xcite .
an often overlooked yet omnipresent case where contact resistance is essential is the junction between nanostructures and reservoirs .
a simplified model , based on lattice dynamics calculations of bulk silicon and of sinws with different diameters , predicts that the contact resistance is dominant over the intrinsic resistance of the ideal nanowire @xcite .
coherent contacts between crystals and nanowires with diameter as small as @xmath57 nm can be actually realized by etching nanowires directly out of the bulk precursor @xcite .
we model the interatomic interactions between silicon atoms by means of the short - range empirical forcefield after tersoff @xcite
. crystalline sinws with diameters between 2 and 14 nm are considered .
the wires are grown in the ( 100 ) crystallographic direction , have a nearly circular cross section and are coherently connected to the bulk reservoir .
the surface is reconstructed in order to minimize the number of dangling bonds @xcite .
transmission spectra are displayed in [ fig : transmission](a ) along with the interface conductance @xmath58 ( b ) obtained by integrating the transmission coefficient over the whole frequency spectrum according to [ landauerformula ] .
the data sets are normalized according to the interface area , as one would reasonably expect the conductance of a junction to scale with its cross section area .
in fact such normalization makes curves comparable , but not overlapping .
normalized transmission spectra and @xmath59 curves overlap for wires of 7 and 10 nm diameter ( red and pink curves in [ fig : transmission ] ) . whereas heat transport in thicker wires can be treated within a mesoscopic approach @xcite , below this threshold , one has to consider explicitly the atomistic details of the interface to obtain an accurate estimate of the contact conductance . as the construction of the bulk - wire interface is ideal at the atomic scale ,
our calculations provide an upper limit to the contact conductance . in the low temperature regime (
@xmath60 k ) the interface area normalized contact conductances collapse to a single curve and display a temperature dependence of @xmath61 .
this trend was formerly predicted analytically @xcite and confirmed in experiments @xcite , where it was shown that deviations from the @xmath61 behavior stem from specific features of the sinw , such as surface roughness , the effects of which add up in series to the contact conductance . on the other hand
we observe that the reflection spectrum ( not shown ) , scales with the linear dimension of the contact interface , which seems to indicate that back scattering of phonons mostly happens at the perimeter of the junction .
normalized reflection spectra nearly coincide for wires with a diameter larger than 7 nm .
[ [ representation - of - the - heat - flux . ] ] representation of the heat flux .
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + an advantage of the present implementation of the scattering matrix method is that it provides a real - space representation of the energy flux at any given frequency .
this allows visualization of the parts of the system that primarily transmit or reflect thermal energy .
an example is shown in [ fig : fluxes ] , where the norm of the heat flux across a bulk-10 nm sinw interface is represented .
phonon branches at 0.25 , 0.75 , 2 and 4 thz are considered .
the spacial features of heat transport at different frequencies are clearly different : whereas at the lowest frequency ( 0.25 thz ) thermal energy is mainly transmitted through the central bulk - like part of the wire , at higher frequencies ( 0.75 and 2 thz ) thermal energy is transferred through a surface layer .
beyond 4 thz heat is transferred through the center of the wire .
we note that phonons with frequency between @xmath62 and @xmath63 thz , which are the majority heat carriers in crystalline si at room temperature , transfer energy preferably through a sub - surface layer .
therefore our results indicate the reason why thermal conductivity of sinw is so sensitive to surface modifications , such as disorder or presence of interfaces @xcite . [
[ dimensionality - and - shape - effects . ] ] dimensionality and shape effects .
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + in order to probe the effects of shape and dimensionality reduction on the contact conductance we compare the number of phonon channels ( corresponding to the density of states ) over the whole frequency spectrum , in contacts made of crystalline bulk silicon and either wires with a circular section or square rods .
we only consider sinw larger than the threshold size of 7 nm , identified as the onset for a mesoscopic theory of thermal transport .
the calculations have been performed for sinw with diameters up to 14 nm .
the data are conveniently normalized with respect to the contact surface area and are compared to the number of channels in three - dimensional periodic bulk . to verify size convergence we consider two bulk samples with cubic supercell of 8.7 and 13 nm , respectively ( [ fig : channels ] ) .
our data show that for sinws larger than 7 nm , the number of channels per atom at a given frequency does not depend on the diameter .
the number of channels at low frequency ( @xmath64 thz ) for the contacts is the same as in the crystalline bulk , but it deviates significantly from the bulk at larger frequencies .
this means that even in contact interfaces with very large wires , one can not expect to recover bulk - like thermal conductance .
it also indicates that dimensionality reduction has a profound effect on the limit density of states as well .
such a limit depends also on the shape of the sinw , but to a minor extent .
the spectrum of square shaped nanorods differs from that of circular ones in the medium - to - high frequency range , but it retains similar features as cylindric wires and does not seem to approach the 3d bulk limit either .
we have developed an efficient method based on the scattering matrix approach to compute the thermal conductance in an open system .
our derivation leads to an expression of the energy flux between two reservoirs across a defect region , equivalent to the one derived in refs .
however , our implementation differs from the traditional green s function approach , as it circumvents the bottleneck imposed by the inversion of large matrices , and allows real size devices to be simulated at the atomistic level .
we have used this approach to compute the contact thermal conductance of ideal junctions between bulk silicon and silicon nanowires of different diameters .
our results show that beyond a threshold diameter of 7 nm phonon transmission , reflection and thermal conductance obey simple scaling laws , whereas deviations are observed for thinner wires .
our approach also provides a direct space visualization of frequency dependent heat flux , which yields valuable insight into the spatial features of heat conduction in nanoscale devices .
calculations were performed on the ibm power6 system at the rechenzentrum garching .
i.d . acknowledges support from the multiscale materials modeling initiative of the max planck society .
the authors thank k. kremer and c. joachim for useful suggestions , and l.f .
pereira and l. pavka for critical reading of the manuscript . | we have developed an efficient scalable kernel method for thermal transport in open systems , with which we have computed the thermal conductance of a junction between bulk silicon and silicon nanowires with diameter up to 10 nm .
we have devised scaling laws for transmission and reflection spectra , which allow us to predict the thermal resistance of bulk - nanowire interfaces with larger cross sections than those achievable with atomistic simulations .
our results indicate the characteristic size beyond which atomistic systems can be treated accurately by mesoscopic theories . |
super star clusters ( sscs ) and globular clusters ( gcs ) represent the youngest and the oldest stellar aggregates known in the universe .
the environments in which these two kinds of clusters are found are vastly different sscs are found in violent star - forming regions , whereas gcs are found in the halos of galaxies .
yet , the similarity in their compactness and mass , is a reason compelling enough to think of an evolutionary connection between them .
the growing popularity of the hierarchical model of galaxy formation in the years following the discovery of sscs , and the possibility of observing the epochs of galaxy ( and gc ) formation at high redshifts , have also generated interest in looking for a common origin for these two seemingly different classes of clusters . in order to investigate the relation between the two types of clusters , it is important to analyze the survival of sscs for a hubble time .
star clusters are vulnerable to a variety of disruption processes that operate on three different timescales . on short timescales ( @xmath2 yr ) , the exploding supernovae and the resulting superwinds are responsible for cluster expansion and disruption , a process popularly dubbed as infant mortality . on intermediate timescales ( @xmath3 yr ) , the mass - loss from evolving stars leads to the disruption of the clusters . on even longer timescales ( @xmath4 yr ) , stellar dynamical processes , especially evaporation due to two - body scattering , and tidal effects on a cluster as it orbits around the galaxy , known as gravitational shocks ,
come into play in the removal of stellar mass from clusters .
the gcs represent those objects that have survived all these processes , whereas young sscs are just experiencing them .
intermediate age sscs are the ideal objects to investigate the influence of disruption processes on the survival of star clusters .
almost all the star formation in the disk of m82 took place in a violent disk - wide burst around 100500 myr ago , following the interaction of m82 with the members of m81 group @xcite .
cluster formation is known to be efficient during the burst phase of star formation @xcite , and hence we expect large number of clusters of intermediate age ( @xmath5 myr ) in its disk .
hence , m82 offers an excellent opportunity to assess the evolutionary effects on the survival of star clusters , and to look for a possible evolutionary connection between the sscs and gcs .
the observational data used in this work consisted of images in f435w ( @xmath6 ) , f555w ( @xmath7 ) and f814w ( @xmath8 ) filters , that were obtained by the hubble heritage team @xcite using the acs / wfc instrument aborad the hubble space telescope ( hst ) .
bias , dark , and flat - field corrections were carried out using the standard pipeline process by the heritage team .
the final reduced science quality images cover the entire optical disk of the galaxy with a spatial sampling of 0.05 arcsecpixel@xmath9 , which corresponds to 0.88 parsecpixel@xmath9 at m82 s distance of 3.63 mpc @xcite .
the point sources have a size distribution that peaks at a full width at half maximum ( fwhm ) of 2.1 pixels , with the tail of the distribution extending to 3.0 pixels ( or 2.6 parsec ) .
very few clusters are expected to have sizes smaller than 3 parsec , and hence clusters can be distinguished from the stars on these images . a circle of 500 pixels ( 450 pc ) radius is used to separate the nuclear region from the disk .
the clusters inside this radius are associated with strong h@xmath10 emitting complexes , and hence are younger than 10 myr @xcite . on the other hand , the disk outside the 450 pc radius shows characteristic signatures of post - starburst conditions , with hardly any h@xmath10 emission .
we used sextractor @xcite independently on the @xmath6 , @xmath7 , and @xmath8-band images to construct an unbiased sample of cluster candidates . a source
having a fwhm @xmath11 pixels and an area of at least 50 adjacent pixels , each of s / n @xmath12 is considered a cluster candidate .
all the bright sources satisfying these criteria are genuine clusters , but at fainter magnitudes majority of the candidate sources lack the symmetry expected for a physical cluster .
these are found to be artificial extended sources formed due to the superposition of stars in this nearly edge - on galaxy .
these artificial sources most often are elongated , and are rejected automatically from the sample using the ellipticity parameter of sextractor .
cluster candidates in each filter were then combined , the common sources being counted only once .
the resulting list contains 653 clusters , 260 of them belonging to the nuclear region .
for all the sources in the final list , aperture photometry is carried out in all the three bands .
the fwhm calculated by sextractor is used as a measure of the size of the clusters .
the observed cluster luminosity function ( lf ) follows a power - law at the bright end , turning over sharply at faint magnitudes .
similarly , the size distribution function peaks at a characteristic value of fwhm@xmath1310 pixels .
monte carlo simulations were carried out to check the effect of incompleteness of cluster detection on the observed functional forms . in the simulations ,
each cluster is assumed to be round and to have a gaussian intensity profile of a given fwhm .
a power - law distribution function is used to assign a luminosity to each cluster .
two separate simulations are done , one in which a cluster is assigned a size based on a power - law size distribution function , and the other based on a log - normal function .
the simulated luminosity function resembles very much the observed one , implying that the observed turn - over of the luminosity function is due to incompleteness at the faint end and not intrinsic to the cluster population .
hence , the turn - over in the luminosity function , if any , would correspond to a magnitude fainter than @xmath14 mag . on the other hand , the observed size function points to an intrinsically log - normal size distribution , rather than a power - law function . a more detailed description of the selection process , observed luminosity and size functions , and the monte carlo simulations can be found in @xcite .
we analyzed the color and magnitude of the individual clusters to obtain their reddening and mass , making use of solar metallicity single stellar population ( ssp ) models of @xcite .
these authors provide the evolutionary data on colors and magnitudes for the instrumental hst / acs filters , a fact that enables us a direct comparison with the observed data .
the @xcite initial mass function ( imf ) in its corrected version has been used .
it has nearly a salpeter slope ( 2.30 instead of 2.35 ) for all masses higher than 1 @xmath15 .
the derived masses depend on the assumption of the lower cut - off mass of the imf . in the case of standard kroupa s imf
, the derived masses would be around 2.5 times higher .
colors obtained by the combination of the three filters that we used suffer from age - reddening degeneracy , and hence it was necessary to assume one of the quantities to obtain the other .
we found that the observed range in colors is too large to be explained by evolutionary effects , even for stellar populations as old as 10 gyr . on the other hand , age of the principal stellar populations in the nuclear region of m82
is determined in innumerable studies ( * ? ? ?
* ; * ? ? ?
* and references therein ) , and it is found to be @xmath16 myr . based on these studies , we adopt an age of 8 myr for the nuclear clusters .
most of the disk stars in m82 were formed in a violent burst around 500 myr ago .
ages of those clusters for which spectroscopic data are available @xcite lie in the range between 50500 myr , suggesting that the clusters are formed during or immediately after the disk - wide star formation epoch .
@xmath15 is superposed .
two vectors , placed at 8 myr and 500 myr , show the location of the track reddened by @xmath17 mag . in the top - right panel
, we show the cmd for the nuclear clusters only .
the locations of an 8 myr ssp for a range of cluster masses and visual extinctions are shown by the superposed grid .
mass varies vertically along the grid ( in solar units ) , whereas the visual extinction ( in magnitude ) varies along the diagonal axis . in the bottom panels , we show a similar diagram for the disk clusters , with the superposed grids corresponding to fixed ages of 100 myr ( left ) and 500 myr ( right ) . in all the panels ,
tick mark values of the right - vertical axis correspond to the absolute magnitude in the @xmath7-band .
[ fig_cmds ] , height=453 ] from the assumed ages ( 8 myr for the nuclear clusters , and 50500 myr for the disk clusters ) , and the very likely hypothesis that the extinction is the main cause of the dispersion in the observed colors , we can estimate the masses of the clusters .
the method we have followed is illustrated in figure [ fig_cmds ] .
for a given position in the color magnitude diagram ( cmd ) , we derived the extinction by comparing the observed colors with those of the ssp . once the extinction is determined , we calculate the mass using the extinction - corrected luminosity and the mass - to - light ratio of such ssp
. the disk masses are derived assuming an age of 100 myr .
the mass estimates would be higher by a factor of 3.2 , if the clusters are as old as the stellar disk ( 500 myr ) .
on the other hand , if the clusters are as young as 50 myr , the masses would be lower by a factor of 1.6 .
the distribution of the derived visual extinction values is peaked at @xmath18 mag for the disk clusters , whereas it is flat between 14 mag for the nuclear clusters .
@xmath15 and @xmath19@xmath15 .
the best - fit indices in this mass range are indicated .
( right ) mean size ( fwhm ) of the clusters as a function of mean mass for three mass bins for the nuclear ( young ) and disk ( old ) samples .
the error bar denotes the rms dispersion about the mean value .
high mass clusters have similar mean sizes irrespective of their evolutionary status .
on the other hand , mean size of the low - mass clusters clearly decreases as they become older . among the young clusters , low - mass ones are more extended than higher mass ones .
[ fig_mass_fun ] , title="fig:",height=207 ] @xmath15 and @xmath19@xmath15 .
the best - fit indices in this mass range are indicated .
( right ) mean size ( fwhm ) of the clusters as a function of mean mass for three mass bins for the nuclear ( young ) and disk ( old ) samples .
the error bar denotes the rms dispersion about the mean value .
high mass clusters have similar mean sizes irrespective of their evolutionary status .
on the other hand , mean size of the low - mass clusters clearly decreases as they become older . among the young clusters , low - mass ones are more extended than higher mass ones .
[ fig_mass_fun ] , title="fig:",height=207 ] the determination of the cluster masses for our complete sample enables us to derive the present - day cluster mass function ( cmf ) . in the left panel of figure [ fig_mass_fun ]
, we plot the cmf separately for the nuclear and disk clusters .
the nuclear cmf is scaled up to match the disk cmf at @xmath20 @xmath15 .
poissonian error bars are indicated .
the distribution for both samples follows a power - law over almost two orders of magnitude in mass for cluster masses above @xmath21 @xmath15 .
however , the power - law index for the disk and nuclear cluster populations shows a clear difference , @xmath22 for the nuclear clusters , and @xmath23 for the disk population .
studies of young star clusters in nearby galaxies yield a value of @xmath10 close to 2.0 @xcite .
hence , @xmath24 can be considered as the expected slope of the initial cmf . in general , the cluster size distribution function ( csf ) for the nuclear and disk clusters
follow a log - normal form . however , the mean , as well as the maximum cluster sizes are systematically smaller for the lower mass bins .
this tendency is illustrated in the right panel of figure [ fig_mass_fun ] , where the mean cluster size for each mass bin has been plotted against the mean mass of clusters in that bin , for the young and old ones , separately .
for the highest mass bin , the mean sizes of the young and old clusters are similar .
the mean size decreases systematically with decreasing cluster mass for the old clusters , whereas the inverse is true for the young clusters .
the observed differences in the csf for young and old clusters are consistent with the expected evolutionary effects .
both the disruption of the loose ob associations and the dynamical trend towards relaxation would diminish the number of large low - mass systems .
thus , the destruction process is both mass and size dependent , with the most extended clusters in each mass bin being the most vulnerable to disruption .
all clusters of masses higher than @xmath25 @xmath15 are still surviving @xmath26 yr after their formation . in this section , we discuss these observational results in the context of theoretical models of cluster disruption , and their possible survival to become globular clusters . at early times
, disruption is caused mainly due to the expulsion of the intra - cluster gas through supernova explosions .
this process is ineffective once all the high mass stars in the cluster die , which happens in around @xmath27 myr .
hence , the observed disk clusters have survived this early mechanism of disruption . on intermediate timescales ( @xmath3 yr )
, the mass - loss from evolving stars leads to a decrease in the cluster mass from its initial value .
clusters can loose as much as 30% of their stellar mass during their evolution .
the decreased cluster mass can result in the expansion of the cluster , finally leading to its disruption .
however , this process of disruption is equally effective for high and low mass clusters , and hence a change in the slope of mass function is not expected .
the observed flattening of the mass function at older ages , suggests that the cluster disruption process that is active in m82 selectively destroys low - mass clusters .
the tidal effect experienced by the clusters as they move in the gravitational field of the parent galaxy is one such process . according to @xcite ,
this process becomes important after @xmath28 myr in normal galaxies .
however , in the case of m82 , @xcite have estimated a disruption timescale as short as 30 myr for a cluster of mass @xmath29 @xmath15 at 1 kpc away from the center , with a dependence on mass that varies as @xmath30 .
the short timescale in m82 implies that the surviving clusters in the disk are presently experiencing the dynamical processes of cluster disruption .
if the trend of selective disruption of loose clusters continues , how many of the present clusters will survive for a hubble time ?
can the lf of the surviving clusters look like that of the galactic gcs ? in figure [ fig_lumfun ] , we show the evolutionary effects on the lf of the m82 clusters .
the histogram with dashed lines shows the lf considering the photometric evolution of the clusters for 5 gyr , whereas the solid histogram shows the same , but after taking into account the dynamical effects as well .
the latter is implemented in a simplistic way , by imposing the condition that for the clusters to survive the dynamical effects , their half - light radius , @xmath31 , should be smaller than the tidal radius , @xmath32 , for that cluster . for a cluster of mass @xmath33 at galactocentric radius @xmath34 ,
@xmath32 is given by the expression @xcite , + @xmath35 , + where @xmath36 is the mass of the parent galaxy , which for m82 is somewhat uncertain due to the difficulty in interpreting uniquely the observed gas velocity fields in this disturbed galaxy , and the best estimate is @xmath37@xmath15@xcite .
the @xmath32 values calculated using the currently observed galactocentric distances indicate that most of the nuclear clusters , and very few of the disk clusters , will be destroyed .
thus , if the clusters are in circular orbits , the lf will practically retain its present power - law form . however , the stellar orbits in the central bar of m82 are known to be highly elliptical @xcite , which implies that the galactocentric distance of a cluster will change with time .
the disruption of a cluster depends on the net tidal force received by its stars as it orbits the galaxy during its lifetime .
we found that for an assumed @xmath38 pc , the future lf of m82 will resemble that of the galactic gcs . even in this extreme case ,
85 clusters will survive , as compared to the 146 gcs in the milky way .
the number of gcs in a galaxy scale with the mass of the parent galaxy , and considering that m82 is an order of magnitude less massive than the milky way , only @xmath39 gcs are expected to present in m82 .
thus , number of clusters that will survive represent an over - abundance by a factor of 56 . for ages older than this ,
the distribution is similar except that the peak of the distribution shifts to @xmath130.5 mag fainter .
thus , the compact star clusters in m82 will evolve into gcs .
, height=415 ]
luminosity and mass functions of star clusters in m82 follow power - law functions , with the power law index showing a tendency for flattening of the profile with age . in other words , there is a deficiency of low - mass clusters among the older clusters . we also find the mean size of the older clusters to be smaller as compared to the younger clusters for masses @xmath40 @xmath15 .
these two results together imply the selective destruction of loose clusters .
the tidal forces experienced by the clusters as they orbit around the galaxy lead to exactly such a destruction process .
if this process continues in m82 , the lf of surviving clusters can mimic the presently observed lf of the galactic gcs , provided the clusters move around the galaxy in highly elliptical orbits , with perigalactic distance as small as 350 pc .
the resulting lf contains 85 clusters with the function peaking at the same luminosity as for the galactic gcs at 5 gyr age , and fainter by @xmath130.5 mag at 10 gyr . on the other hand ,
if the clusters move in nearly circular orbits , the lf will retain the power - law form , with the number of surviving clusters even higher .
this work is partly supported by conacyt ( mexico ) research grants 42609-f and 49942-f .
we would like to thank the hubble heritage team at the space telescope science institute for making the reduced fits files available to us .
bastian , n. , gieles , m. , lamers , h. j. g. l. m. , scheepmaker , r. a. , & de grijs , r. 2005 , a&a , 431 , 905 bertin , e. , & arnouts , s. 1996 , a&as , 117 , 393 de grijs , r. , anders , p. , bastian , n. , lynds , r. , lamers , h. j. g. l. m. , & oneil , e. j. 2003 , mnras , 343 , 1285 de grijs , r. , parmentier , g. , & lamers , h. j. g. l. m. 2005 , mnras , 364 , 1054 | recent hst / acs images of m82 covering the entire galaxy have been used to detect star clusters .
the galaxy is known to contain a young population ( age @xmath0 yr ) in its starburst nucleus , surrounded by a post - starburst disk of age @xmath1 yr .
we detect more than 650 star clusters in this galaxy , nearly 400 of them in the post - starburst disk .
these data have been used to derive the luminosity , mass and size functions separately for the young nuclear , and intermediate - age disk clusters . in this contribution
, we discuss the evolutionary status of these clusters , especially , on the chances of some of these clusters surviving to become old globular clusters . |
SECTION 1. SHORT TITLE.
This Act may be cited as the ``Vision Care for Kids Act of 2009''.
SEC. 2. GRANTS REGARDING VISION CARE FOR CHILDREN.
Part Q of title III of the Public Health Service Act (42 U.S.C.
280h et seq.) is amended by adding at the end the following:
``SEC. 399Z-1. GRANTS REGARDING VISION CARE FOR CHILDREN.
``(a) In General.--The Secretary, acting through the Director of
the Centers for Disease Control and Prevention, may award grants to
States on the basis of an established review process for the purpose of
complementing existing State efforts for--
``(1) providing comprehensive eye examinations (as defined
in subsection (i)) by a licensed optometrist or ophthalmologist
for eligible children (as defined in subsection (b)) who have
been previously identified through a vision screening or eye
examination by a licensed health care provider or vision
screener as needing such services, with priority given to
children who are under the age of 9 years;
``(2) providing treatment or services to such children,
subsequent to the examinations described in paragraph (1), that
are necessary to correct vision problems; and
``(3) developing and disseminating, to parents, teachers,
and health care practitioners, educational materials on
recognizing signs of visual impairment in children.
``(b) Eligible Children.--
``(1) In general.--For purposes of this section, the term
`eligible child' means, with respect to an examination
described in paragraph (1) of subsection (a) or a treatment or
service described in paragraph (2) of such subsection and with
respect to a State, a child who is a low-income child (as
defined by the State) and who--
``(A) is not eligible for medical assistance under
the State plan under title XIX of such Act;
``(B) subject to paragraph (2)(A), is not eligible
for child health assistance under the State child
health plan under title XXI of the Social Security Act;
``(C) subject to paragraph (2)(B), does not have
health insurance coverage (as defined in section 2791)
in the group market or in the individual market (as
such terms are defined in such section) and is not a
beneficiary or participant under a group health plan
(as defined in such section); and
``(D) is not receiving assistance under any State
health compensation program or under any other Federal
or State health benefits program for such examination,
treatment, or service, respectively.
``(2) Inclusion of certain low-income children with health
benefits.--With respect to an examination described in
paragraph (1) of subsection (a) or a treatment or service
described in paragraph (2) of such subsection and with respect
to a State--
``(A) paragraph (1)(B) shall not apply to a child
who is eligible for child health assistance under the
State child health plan under title XXI of the Social
Security Act (whether or not such child is enrolled
under such plan), if such plan does not provide for
coverage of such examination, treatment, or service,
respectively; and
``(B) paragraph (1)(C) shall not apply to a child
described in such paragraph if no amount is payable
under the coverage or plan described in such paragraph
for such examination, treatment, or service,
respectively.
``(c) Criteria.--The Secretary, in consultation with appropriate
professional and patient organizations including individuals with
knowledge of age appropriate vision services, shall develop criteria--
``(1) governing the operation of the grant program under
subsection (a); and
``(2) for the collection of data related to vision
assessment and the utilization of follow-up services.
``(d) Application.--To be eligible to receive a grant under
subsection (a), a State shall submit to the Secretary an application in
such form, made in such manner, and containing such information as the
Secretary may require, including--
``(1) information on existing Federal, Federal-State, or
State-funded children's vision programs;
``(2) a plan for the use of grant funds, including how
funds will be used to complement existing State efforts
(including possible partnerships with non-profit entities);
``(3) a plan to determine if an eligible child has been
identified as provided for in subsection (a);
``(4) an assurance that funds will be used consistent with
this section;
``(5) a description of how funds will be used to provide
examinations, treatments, and services, consistent with this
section; and
``(6) an assurance that, in providing examinations,
treatments, and services through use of such grant, the State
will give priority to eligible children with the lowest income.
``(e) Evaluations.--To be eligible to receive a grant under
subsection (a), a State shall agree that, not later than 1 year after
the date on which amounts under the grant are first received by the
State, and annually thereafter while receiving amounts under the grant,
the State will submit to the Secretary an evaluation of the operations
and activities carried out under the grant, including--
``(1) an assessment of the utilization of vision services
and the status of children receiving these services as a result
of the activities carried out under the grant;
``(2) the collection, analysis, and reporting of children's
vision data according to guidelines prescribed by the
Secretary; and
``(3) such other information as the Secretary may require.
``(f) Limitations in Expenditure of Grant.--A grant may be made
under subsection (a) only if the State involved agrees that the State
will expend amounts received under such grant as follows:
``(1) The State will expend at least 80 percent of such
amounts for the purposes described in paragraphs (1) and (2) of
such subsection.
``(2) The State will not expend more than 10 percent of
such amounts to carry out the purpose described in paragraph
(3) of such subsection.
``(3) The State will not expend more than 10 percent of
such amounts for administrative purposes.
``(g) Matching Funds.--
``(1) In general.--With respect to the costs of the
activities to be carried out with a grant under subsection (a),
a condition for the receipt of the grant is that the State
involved agrees to make available (directly or through
donations from public or private entities) non-Federal
contributions toward such costs in an amount that is not less
than 25 percent of such costs.
``(2) Determination of amount contributed.--Non-Federal
contributions required in paragraph (1) may be in cash or in
kind, fairly evaluated, including plant, equipment, or
services. Amounts provided by the Federal Government, or
services assisted or subsidized to any significant extent by
the Federal Government, may not be included in determining the
amount of such non-Federal contributions.
``(h) Supplement Not Supplant.--A State that receives a grant under
this section shall ensure that amounts received under such grant will
be used to supplement, and not supplant, any other Federal, State, or
local funds available to carry out activities of the type carried out
under the grant.
``(i) Definitions.--For purposes of this section:
``(1) Child.--The term `child' means an individual who--
``(A) has not attained 18 years of age; or
``(B) has not attained 19 years of age and is a
full-time student in a secondary school (or in the
equivalent level of vocational or technical training).
``(2) Comprehensive eye examination.--The term
`comprehensive eye examination' includes an assessment of a
patient's history, general medical observation, external and
ophthalmoscopic examination, visual acuity, ocular alignment
and motility, refraction, and as appropriate, binocular vision
or gross visual fields, performed by an optometrist or an
ophthalmologist.
``(j) Authorization of Appropriations.--For the purpose of carrying
out this section, there are authorized to be appropriated--
``(1) $10,000,000 for fiscal year 2010;
``(2) $13,000,000 for fiscal year 2011; and
``(3) $14,000,000 for each of the fiscal years 2012 through
2014.''.
Passed the House of Representatives March 31, 2009.
Attest:
LORRAINE C. MILLER,
Clerk. | Vision Care for Kids Act of 2009 - Amends the Public Health Service Act to authorize the Secretary of Health and Human Services, acting through the Director of the Centers for Disease Control and Prevention (CDC), to award matching grants to states to complement existing state efforts to: (1) provide comprehensive eye examinations from a licensed optometrist or ophthalmologist to eligible children who have been previously identified through a vision screening or eye examination by a licensed health care provider or vision screener as needing such services, with priority given to children who are under the age of nine years; (2) provide treatment or services as necessary to correct identified vision problems; and (3) develop and disseminate to parents, teachers, and health care practitioners educational materials on recognizing signs of visual impairment in children. Defines "eligible child" as a low-income child who: (1) is not eligible for medical assistance under Medicaid; (2) is not eligible for child health assistance under the State Children's Health Insurance Program (SCHIP), unless such plan does not provide coverage of such examination, treatment, or service; (3) does not have health insurance coverage unless no amount is payable under the coverage for such examination, treatment, or service; and (4) is not receiving assistance under state health compensation program or any other federal or state health benefits program.
Requires the Secretary to develop criteria: (1) governing the operation of the grant program; and (2) for the collection of data related to vision assessment and the utilization of follow-up services. |
the vli method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift .
the variability of task characteristics , such as the weight of the load being lifted and the geometry of the lift ( e.g. , horizontal reach , vertical height , etc . ) , between lifts in manual lifting jobs within industry makes it difficult to assess their overall physical demand or risk of musculoskeletal disorder .
generally , manual lifting jobs in industry can be categorized according to the variability of the task characteristics between lifts within the job . as described by waters , occhipinti , colombini , alvarez , and hernandez ( 2009 ) ,
the four categories of lifting are as follows : single - task manual lifting involves task characteristics that do not vary significantly from lift to lift or only one lift is of interest .
examples of this category of task may include performing a single heavy lift per day or the lifting of the same part repetitively on assembly lines .
multiple - task manual lifting involves jobs that consist of a small set of unique repetitive lifting tasks ( less than 10 ) that may be performed concurrently during a prescribed period of time .
sequential manual lifting involves tasks in which a worker rotates between different workstations during a shift or other period of time . at each workstation
, the worker has to perform a different series of specified lifting tasks and each rotation position in the job may have its own set of unique single- or multitask lifting activities .
variable - task manual lifting involves jobs where all of the lifts are highly variable .
. examples of this category of task may include manual lifting in warehouse operations , baggage handling , and small lot material delivery in assembly line manufacturing operations .
( 2009 ) first described a new method , the variable lifting index ( vli ) , to assess the physical demands of jobs with variable manual lifting tasks . the purpose of the present paper is to expand on the background and application of the vli and to provide two detailed approaches to the use of the vli for industrial practitioners .
historically , jobs with variable task characteristics have been difficult to evaluate , and the need for such an approach has been documented in previous studies .
for example , in a study of grocery order selectors ( also called pickers ) in a dry goods warehouse , waters , baron , and putz - anderson ( 1998 ) attempted to assess the physical demands for selectors due to manual lifting of boxes of groceries . the order selector job involved repetitive lifting of cases of grocery items from supply pallets to an electrically driven pallet jack that moves along the aisles of the warehouse
. to assess the physical demands of the order selector job , a variety of ergonomic assessment tools were used to evaluate the physical demands of the lifting job and a questionnaire was administered to selectors to determine their perceptions of physical workload and symptoms of musculoskeletal disorders .
the ergonomic assessment tools included the single task recommended weight limit ( rwl ) and lifting index ( li ) equations from the revised niosh ( national institute for occupational safety and health ) lifting equation ( rnle ; waters , putz - anderson , & garg , 1994 ) , the university of michigan 3d static strength prediction program ( chaffin & andersson , 1991 ) , an oxylog portable oxygen consumption meter ( o2 ) , a portable heart rate monitor , a lumbar motion monitor , the ohio state university risk assessment model ( marras , fathallah , miller , davis , & mirka , 1992 ) , and the liberty mutual psychophysical method for assessing manual lifting ( snook & ciriello , 1991 ) . based on the results obtained from the warehouse studies , it was apparent that all six of the ergonomic methods used in that study indicated that the job of grocery selector has a high level of risk for low back pain , but there were differences in the predicted level of physical demand and risk of low back pain derived from the various methods .
the authors stated that variability in task characteristics between lifts associated with the grocery selector job presented a problem for nearly all of the assessment methods applied .
when the conditions vary significantly between exertions , there is little capability to accurately evaluate these variations .
the authors also suggested that more research is needed to develop sampling methods that allow integration of variable physical loading between tasks and across a work shift .
another example of manual handling jobs with highly variable task characteristics is provided by the just - in - time or material pull system where small lots of material are in large part manually delivered to production lines in production line manufacturing systems .
the pull systems were commonly called kanban from the japanese term meaning label . the systems require the delivery of small lots of material in totes or containers to production lines and may involve great variety in the weights , sizes , and frequency of items delivered to production lines . the ergonomics issues with such systems and the challenges in the analysis of industrial small lot material delivery jobs
two of the authors of the present paper , waters and fox , contributed to an industry group effort at modifying the niosh 1991 lift equation to address such variable tasks ( automotive industry action group , 2007 ) .
mirka et al . developed the continuous assessment of biomechanical stress ( cabs ) method to assess variable manual lifting jobs ( mirka , kelaher , todd nay , & lawrence , 2000 ) .
the cabs method was designed to allow the accumulation of loading across variable lifts in the construction industry and was used to assess jobs with variable manual materials handling ( mmh ) requirements in the crab fishing industry ( mirka , shin , kucera , & loomis , 2005 ) .
others have developed cumulative load models based on assessment of biomechanical loads for individual lifts that were then added together to obtain a measure of overall load as a function of time ( kumar , 1990 ; norman et al .
, 1998 ; seidler et al . , 2001 ; stuebbe , genaidy , karwowski , young , & alhemood , 2002 ) . in this paper ,
the rnle is likely more familiar and assessable to a greater number of potential users .
the basic vli method for assessing variable lifting jobs was described in a study by waters et al .
the concept for the vli is analogous to that of the composite lift index ( cli ) ( waters et al . , 1994 ) , although frequency independent lift index ( fili ) categories are defined into which the individual lifting tasks are aggregated .
these fili categories are then treated as if they were individual lifts in the cli equation with the frequency multiplier ( fm ) for each category determined from the average frequency of lifts within each of the individual fili categories .
based on the fili and fm values for each category , the vli for the job ( frequency - weighted estimate of the overall physical demand of the job itself ) is calculated .
although as many as nine fili categories can be used , we choose to use six categories in the current model , as numerically it seemed that six categories cover a range of fili more efficiently than a lesser or greater number of categories .
the two different approaches for obtaining the data needed to apply the vli procedure for a highly variable manual lifting job were first suggested by waters et al .
( 2009 ) and colombini , occhipinti , alvarez , hernandez , and waters ( 2009 ) .
those approaches will be explained in more detail in this paper with detailed examples provided .
the first approach is referred to as the sampling approach and requires that task data be obtained from a subset of the lifts that occur during a shift .
the sufficient number of samples required will differ , depending upon the range of variability of the lifting tasks performed during the day .
the second approach is referred to as the systematic organizational analysis approach and is based on a comprehensive assessment of the lifting tasks in order to analytically determine the overall duration of the variable lifting task in the shift .
data collected or estimated include the number of objects of different weight lifted during this time , the number of workers involved , the overall frequency of lifts , the partial frequency of lifts for each weight ( or group of similar weights ) , and finally , by direct observation of workplaces and using a probabilistic approach , the approximate frequencies of individual lifts .
the second approach utilizes production or sales data ( for durations , weights , and overall and partial frequencies ) or probability distribution data ( for geometries and subpartial frequencies ) .
this approach may require some simplifications or assumptions about the weights lifted and the geometries of the lifts during a shift to be used in the rnle ( waters , putz - anderson , garg , & fine , 1993 ; waters et al . , 1994 )
regardless of the approach used , it is necessary to determine the overall average lifting frequency across the work shift , relative work / rest patterns , weights of loads lifted , and measured or predicted geometries of lifts .
the overall frequency of lifting likely will vary from day to day , but a single estimate is needed in order to arrive at the partial frequencies for each category of fili values .
the relative pattern of work / rest is determined as explained in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
it should be noted here that the required ratio of work time to rest time for the short duration category was changed from 1.2 to 1.0 in 2006 ( waters , 2006 ) .
the steps in the vli analysis will differ , depending upon whether the sampling approach or the systematic organizational analysis approach
collect task data needed to compute the fili and single task lifting index ( stli ) for each lift from a subset of lifts performed by the worker during a shift
. the sample should be representative of the distribution of task characteristics and relative frequencies of tasks .
assign each sampled lift into the appropriate fili category and determine the average frequency of lifts in each of the categories . calculate the vli using the cli equation , but use the frequency data for each li category to calculate the appropriate fm values for the calculation .
the vli is computed as follows : the li categories are renumbered in order of decreasing physical stress , beginning with the task category with the greatest stli , down to the task category with the smallest stli .
the stli is defined as the li value for each task or task category , independent of the other tasks or categories .
the vli for the job is then computed according to the following formula ( same formula as used for the cli as in waters et al . , 1994 ) :
li=(fili2x(1fm1,21fm1))+(fili3x(1fm1,2,31fm1,2))+(fili4x(1fm1,2,3,41fm1,2,3)) .+(filinx(1fm1,2,3,4, ,n1fm1,2,3, ,(n1 ) ) )
the numbers in the subscripts refer to the new li task category numbers , and the fm values are determined from the frequency table published in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
the appropriate fm values are based on the sum of the frequencies for the task categories listed in the subscripts . in order to demonstrate how the vli method can be applied to a variable lifting job ,
a simple example of the sampling approach is provided to show how the vli equation should be applied .
remember , these 25 lifts are a representative subset of the total lifts performed by the worker during the shift .
table 1 displays the object weight , horizontal location , vertical height , vertical displacement , asymmetry angle , coupling , and calculated fili for each of the 25 sampled lifts . for simplicity
, it is assumed that significant control is not required for any of the lifts and the overall lifting frequency across the shift is three lifts per minute .
based on the measured data , it can be seen that the largest fili value sampled for any individual lift was 2.5 and the smallest fili value was 0.3 .
task data for vli hypothetical example note . a = asymmetry angle ; c = coupling quality ; d = vertical displacement ( in . ) ;
fili = frequency independent lift index ; h = horizontal distance ( in . ) ; li cat = lifting index category for vli calculation ; rwl = recommended weight limit ( lb ) ; stli = single task lifting index ; v = vertical height ( in . )
; vli = variable lifting index ; wt = object weight ( lb ) . according to the vli procedure
, the range of fili categories should be evaluated and a set of fili categories should be chosen .
this is accomplished by dividing the overall range of fili values into a fixed number of equal size categories .
the choice of fili categories is somewhat arbitrary , but we suggest choosing six categories . for this example
, six fili categories were chosen . in order to determine the spans for the six categories ,
the difference between the maximum fili and the minimum fili is divided by the number of categories ( six ) .
thus , each category would span a range of 2.2/6 or 0.366 units on the li scale , resulting in six categories defined as 0.30.67 , 0.681.0 , 1.11.4 , 1.51.8 , 1.92.1 , and 2.22.5 .
each lift is then assigned to one of the six categories based on the magnitude of the fili values .
the representative fili value for the category containing the single task with the largest fili is assigned that maximum value ( a value of 2.5 in table 2 ) .
the representative value within each of the other categories was computed by averaging the fili values for all the sampled lifts in each of the respective categories .
the number of lifts assigned to each category and the percentage of tasks falling into each of the six cells is also shown in table 2 .
the lifting frequency for each category is determined by multiplying the percentage of lifts in each category times the overall frequency ( 3/min ) , as shown in table 2 . as with the sli approach
, the vli approach works best if the job is performed for a full 8-hour shift ( waters , lu , & occhipinti , 2007 ) .
based on the data shown in table 1 , intermediate calculations for the vli example can be computed as shown in table 2 .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this example , we assumed that the overall frequency of lifting across an 8-hour shift is 3/min .
based on the data presented , the vli for this job can be calculated , as follows :
fili2=2.0((1/.84)(1/.85))=0.01
fili3=1.64((1/.77)(1/.84))=0.18
fili4=1.29((1/.68)(1/.77))=0.22
fili5=.90((1/.65)(1/.68))=0.06
fili6=.44((1/.55)(1/.65))=0.12
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.01 + 0.18 + 0.22 + 0.06 + 0.12=3.49 .
in order to demonstrate how variations in lifting frequency within the job affects the overall vli calculation , we can examine a job with the same series of lifts as previously shown but with different task frequencies .
table 3 shows data for the same job as shown in table 2 , but with different frequencies for tasks within the job . as can be seen in table 3 , the number of tasks within each li category is different , because the frequencies of the tasks are different within each category .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this alternate example , we assumed that the representative fili within each category remained the same as before :
fili2=2.0((1/.74)(1/.82))=0.26
fili3=1.64((1/.68)(1/.74))=0.20
fili4=1.29((1/.61)(1/.68))=0.22
fili5=.90((1/.58)(1/.61))=0.08
fili6=.44((1/.55)(1/.58))=0.04
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.26 + 0.20 + 0.22 + 0.08 + 0.04=3.70 .
as can be seen from this example , as the percentage of tasks with larger fili values increases , the vli value of the overall job also increases .
for this example , the increased frequencies of tasks with higher fili values increased the vli of the overall job from 3.49 to 3.7 . similarly , if the percentage of tasks with lower fili values increases , the vli for the overall job would have been lower than before .
the sampling approach , although useful in many practical situations , does present some limitations in that the task variables need to be sufficiently constant during the sampling period and limited in order to keep the representative tasks to no more than 30 . as mentioned previously ,
the systematic organizational analysis approach is based on a systematic assessment of the job using job and task data derived from methods other than sampling methods , such as production or sales data ( existing data for durations , weights , and overall and partial frequencies ) or probability distribution data ( for geometries and subpartial frequencies ) .
this assessment approach requires knowledge of the total duration of the lifting tasks during the work shift , number and weight of the different objects lifted , number of workers who do the lifting , total and partial frequency of lifts , and the work / rest pattern for the job .
all of the lifts performed by a worker are categorized into a maximum number of 30 fili values that are representative of the range of fili values that would be observed in the entire sample .
the frequencies of each of the fili values are then determined from production data ( considering weight groups ) or from probability estimates of the distributions ( considering observed geometries ) . in order to use this approach , several simplifications may be necessary , especially when many different objects are lifted with widely varying weights and geometries .
this is because , without simplifications , the number of individual fili values would be very large ( hundreds and , sometimes , thousands ) and practically impossible to manage .
one approach is to set up a simplified series of weight and geometry values from which a limited set of fili values can be derived .
the following general procedure for simplifying a large number of lifting tasks was suggested by colombini et al .
( colombini et al . , 2009 ; colombini , occhipinti , alvarez - casado , & waters , 2012 ) : 1 .
compress the potential individual lifting tasks in the job into a structure that considers up to a maximum of 30 subtasks ( and corresponding fili and stli ) for different loads ( weight categories , wtcs ) and geometries using the following approach : aggregate up to 5 objects ( weights ) categories.classification of vertical location ( vertical multiplier , vm ) in only two categories ( good / bad).classification of horizontal location ( horizontal multiplier , hm ) in up to three categories ( near , mid , far).presence / absence of asymmetry ( asymmetric multiplier , am ) assessed for each wtc ( by threshold value for all the lifts in the category).daily duration of lifting classified as in the applications manual for the revised niosh lifting equation ( waters et al .
, 1994).frequencies of lifts specifically determined or estimated for each subtask and fili , with fms determined as in the applications manual for the revised niosh lifting equation ( waters et al . , 1994).vertical displacement ( vertical distance multiplier , dm ) and coupling ( coupling multiplier , cm ) are both considered as a constant .
classification of vertical location ( vertical multiplier , vm ) in only two categories ( good / bad ) .
classification of horizontal location ( horizontal multiplier , hm ) in up to three categories ( near , mid , far ) .
presence / absence of asymmetry ( asymmetric multiplier , am ) assessed for each wtc ( by threshold value for all the lifts in the category ) .
daily duration of lifting classified as in the applications manual for the revised niosh lifting equation ( waters et al .
. frequencies of lifts specifically determined or estimated for each subtask and fili , with fms determined as in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
vertical displacement ( vertical distance multiplier , dm ) and coupling ( coupling multiplier , cm ) are both considered as a constant . at the end
it will be possible to compute individual fili and stli for up to 30 subtasks .
once the selected fili values are derived , the entire set of fili values are assigned into a fixed number of fili categories .
the categories can be defined by assigning the fili values according to sextiles of the correspondent fili distribution . once the selected fili values are assigned to the appropriate category ,
the corresponding cumulative frequencies can be computed and applied using the vli concept with frequency weighting .
the study of organizational data is required for all types of lifting jobs including single - task , multitask , variable , or sequential lifting jobs .
the first assessment step is identifying the number or workers involved in manual handling activities with substantially the same task characteristics , such as weights lifted and task geometries .
then the work / rest pattern for the job has to be assessed across the shift ( i.e. , determine the sequence and relative amount of time spent performing manual lifting tasks and other nonmanual handling
activities and/or breaks ) . the various weights and relative number of objects lifted manually in a shift by one worker
first , all of the weights to be lifted are listed in a table ( for this procedure , consider weights from 3 kg up to maximum , by incremental steps of 1 kg ) .
if there are more than five different weights , the weights are aggregated into a maximum of five wtcs by dividing the span of weight values ( i.e. , max .
each of the individual lifts is then aggregated into those five categories , and the overall number of lifts in each category is determined .
finally , an average weight is computed for each wtc that will be used in subsequent computations .
aggregation of several weights lifted by a worker during a shift in five wtcs and computation of correspondent lifting frequency : example for weights ranging from 5 to 15 kg and for a lifting duration of 300 min in a shift from previous data such as number of workers involved in the task(s ) , net duration of manual lifting in the shift ,
total number of objects lifted during a shift , and number of objects within each wtc lifted during a shift , one can determine the overall lifting frequency ( per worker ) and the partial lifting frequency for each wtc ( as shown in table 4 for a lifting duration of 300 minutes in a shift ) .
these partial frequency values are then used in subsequent calculations , along with the appropriate lifting duration scenario ( short , medium , and long ) , to determine the appropriate fms from the traditional fm tables ( for hands height < 75 cm . )
another simplification will likely be needed to account for variability in task geometry among a large number of lifts .
provides for simplification of geometry by collapsing various factors into a small number of possible conditions , such as horizontal and vertical hand location , and task asymmetry .
the following simplifications were recommended : vertical location ( height of hands at lifting origin or destination ) : this variable is reduced to two areas : ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1.nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 .
ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1 .
nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 . in cases where the vertical height exceeds
the maximum recommended vertical height ( > 175 cm ) , the lifts would be considered unsafe .
horizontal location ( maximum hand grasp point away from the body during lifting ) : the horizontal distances were simplified into three areas near , mid , and far .
the three distances are defined as follows : near horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm).mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm).far horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . near
horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm ) . mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm ) . far
horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . in cases where the horizontal distances exceeds the maximum recommended value ( > 63 cm ) ,
asymmetry ( angular displacement of loads off to the side of the body ) : asymmetry is considered collectively for each wtc .
an am of 0.81 is assigned to all the subtasks in a wtc if asymmetry of 45 or more is observed for over 50% of lifting actions in that category .
otherwise the am is set equal to 1 . vertical travel distance ( vertical distance between the height of hands at origin and at destination ) :
it should be underlined that even if the vertical dm is set as a constant , the height of the hands at both the origin and destination of the lift should always be measured and considered .
coupling ( quality or type of grip ) : the contribution of this factor has also been defined as constant .
ideal couplings are very rare , so the cm is defined as a constant equal to 0.90 . by adopting the simplifications and procedures proposed by colombini et al .
( 2009 , 2012 ) , it is possible to analyze a variable lifting task scenario and produce up to ( and no more than ) 30 sets of fili and stli values , one for each of 30 different subtasks ( 5 wtcs 2 vertical location 3 horizontal areas 1 asymmetry condition ) .
after the fili subtasks are determined from the data , the subtasks will be further classified into six li categories and the vli for the overall job will be determined .
this approach is demonstrated in the example that follows . in a metal - working plant , workers load and
unload plastic containers of in - process materials to and from assembly lines for processing .
the task is organized in cycles ; during each cycle , the worker handles various containers in different body postures due to different heights ( of the hands ) at the origin and destination and different horizontal distances .
the work starts at 8 a.m. , there is a break of 10 min at 10 a.m. , and lunch time is at 1:10 p.m. ( it lasts 60 min ; out of official working time ) . in the afternoon
, the activity is the same as in the morning with a 10 min break at 3.10 p.m. and the last 40 min devoted to light work ( no manual handling ) .
table 5 shows the sequence of lifting task , breaks , and light work during the shift .
sequence and duration of lifting task , light work , and breaks for the case study in an 8-hr shift the containers have three different weights ( 6 , 8 , and 13 kg ) ; the respective number of pieces lifted during the shift is shown in table 6 .
type of weights and number of containers lifted by the worker during an 8-hour shift and consequent lifting frequency per type of weight because 1,852 containers are lifted during a 420-min period , the overall lifting frequency is 4.41 lifts per minute .
the partial lifting frequencies for each type ( weight ) of container are as follows : 1.18 lifts / min for the 6 kg containers , 2.94 lifts / min for the 8 kg containers , and 0.29 lifts / min for the 13 kg containers .
( continuous period of manual handling of 120 min + a break of only 10 min + 120 min of manual handling ) .
the lifting activities are performed at different heights ( of the hands ) at the origin and destination and different horizontal distances ; there is minimal lift asymmetry for all lifts ( i.e. , all objects are lifted in front of the body resulting in an asymmetry multiplier = 1.0 ) , and the hand - to - object coupling is poor for all lifts ( i.e. , coupling multiplier = 0.9 ) .
data regarding the geometries at the origin and destination of the lifts , by wtc , is shown in table 7 .
data regarding load and geometry characteristics in this scenario , it is not possible to use the traditional multitask lifting index ( cli ) approach , as there would be up to 50 different individual fili values ( or about 122 if one considers both origin and destination )
. also , the mean frequency of each type of lift would be very low ( about 0.0300.036 lifts / min ) .
because the traditional cli approach can not work , the proposed vli approach , using weight and geometry simplifications , should be used to assess the task . in the presented example , we have only three wtcs ( 6 , 8 , and 13 kg ) ; each of them could have two simplified
( good and bad ) at origin / destination ; in turn , each of them could have one , two , or three simplified variants for horizontal distance ( near , mid , and far ) . because different horizontal distances per wtcs are clearly identified both at origin than at destination
, it results in a total of 14 individual subtasks , as shown in table 8 .
table 8 also displays the corresponding weights , geometries , partial frequency , and fm , fili , and stli values for each of the 14 identified subtasks .
data regarding the 14 resulting subtasks ( and corresponding fili and stli ) by applying the simplifications and the frequency estimation procedures note . a = absent ; cm = coupling multiplier ; dm = distance multiplier ; f = far ; fili = frequency independent lift index ; firwl = frequency independent recommended weight limit ; fm = frequency multiplier ; g = good ; hm = horizontal multiplier ; ld = long duration ; l / h = low or high ; m = medium ; n = near ; p = poor ; stli = single task lifting index ; vm = vertical multiplier . for determining partial frequencies of individual subtasks
, a special procedure has been adopted that takes into account , for each wtc , how many times the height of hands starts or ends , respectively , in a
area , considering small height intervals of 10 cm and then considering how many times each height of hands
( good and bad ) at origin / destination corresponds to different variants for horizontal distance ( near , mid , and far ) both at origin and at destination .
this procedure is a little more complicated than simply assigning an equal frequency to all the combinations present in a wtc , but assisted by proper software , it is a better estimate of the different frequencies in different geometries combinations in a certain category .
for example , for the 6 kg category , we could consider as equally represented all the six possible combinations ( height of hands , good / bad ; horizontal distance , near / mid / far ) and consequently dividing the overall wtc frequency of 1.18 by 6 , thus obtaining partial frequencies for each combination of 0.196 .
however , it is preferable to adopt the more detailed procedure to obtain more accurate estimates of the partial frequencies of individual combinations . using this procedure
, we have that four of nine lifts ( 44.4% ) originate or end in a bad vertical height ( l / h vertical height ) and the other five ( 55.6% ) are in the good vertical height category . for the bad vertical height category
, the lifts will be equally distributed with regard to horizontal reach ( i.e. , one third of the lifts will be near , one third mid , and one third far reaches ) , whereas for the good vertical height category we have one half of the lifts in a near horizontal reach and one fourth , respectively , in the mid and far reach categories . therefore , for the combinations l / h - near , l / h - mid , and l / h - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result always of about 14.8% each ; because the overall frequency of lifts in the 6 kg category is 1.180 lifts per minute , we have for each combination a partial frequency of about 0.175 lifts per minute . for the combinations of good - near , good - mid , and good - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result , respectively , in 27.8% , 13.9% , and 13.9% and the corresponding partial frequencies are 0.328 , 0.164 , and 0.164 .
for the other wtcs , a similar approach has been used to determine individual tasks partial frequencies .
the resulting frequencies of lifts for the various combinations ( 14 in the present example ) of vertical height and horizontal reaches are reported in table 8 . because 14 subtasks are still too many to use directly the cli formula , it is advisable to use the vli concept and approach . to apply the vli approach , subtasks and corresponding data ( fili , frequencies , and stli )
those six categories are determined according to the distribution of the individual fili values ( in this case 14 values ) using preferentially the sextile distributions as key points for grouping ( or in other terms the values corresponding to the 16.6th , 33.3rd , 50th , 66.6th , and 83.3rd percentile of the resulting fili distribution ) . as a simpler alternative
, one may obtain six key points by dividing the range of fili values ( i.e. , maximum fili
minimum fili ) divided by 6 ; this simpler option has , however , some disadvantages ( i.e. , some li category could be empty ; the distribution of fili values could be not well represented ) . in any case , the original frequencies of individual subtasks ( 14 in present case ) are grouped and cumulated in the six li categories . single ( category ) li values could be consequently computed and used for reordering ( from highest to lowest ) the six li categories . within each resulting li category , a representative fili value is chosen : this value is the highest for the highest category ( category number 1 ) ; it corresponds to the mean ( central ) value for all the other five li categories .
relevant values for each fili category using the key points from table 9 and the consequent cumulated frequencies derived from table 8 note .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index . using these data , organized in six fili categories
, it will be possible to compute the vli by means of the traditional cli formula in the same way previously reported for the task sampling approach .
based on the data presented for this example , the computational data for applying the formula vli = stli1 + li are reported in table 11 .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index ; vli = variable lifting index . using data reported in table 11 ,
the vli for this job can be calculated , as follows :
fili2=0.907*[(1/0.698)(1/0.748)])=0.907*(0.096)=0.087
fili3=0.805*[(1/0.672)(1/0.698)]=0.805*(0.055)=0.045
fili4=0.694*[(1/0.590)(1/0.672)]=0.694*(0.207)=0.144
fili5=0.604*[(1/0.475)(1/0.590)]=0.604*(0.410)=0.248
fili6=0.483*[(1/0.409)(1/0.475)]=0.483*(0.340)=0.164
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=1.656 + 0.087 + 0.045 + 0.144 + 0.248 + 0.164=2.34 .
collect task data needed to compute the fili and single task lifting index ( stli ) for each lift from a subset of lifts performed by the worker during a shift .
the sample should be representative of the distribution of task characteristics and relative frequencies of tasks .
assign each sampled lift into the appropriate fili category and determine the average frequency of lifts in each of the categories .
calculate the vli using the cli equation , but use the frequency data for each li category to calculate the appropriate fm values for the calculation .
the vli is computed as follows : the li categories are renumbered in order of decreasing physical stress , beginning with the task category with the greatest stli , down to the task category with the smallest stli .
the stli is defined as the li value for each task or task category , independent of the other tasks or categories .
the vli for the job is then computed according to the following formula ( same formula as used for the cli as in waters et al . ,
1994 ) :
li=(fili2x(1fm1,21fm1))+(fili3x(1fm1,2,31fm1,2))+(fili4x(1fm1,2,3,41fm1,2,3)) .+(filinx(1fm1,2,3,4, ,n1fm1,2,3, ,(n1 ) ) )
the numbers in the subscripts refer to the new li task category numbers , and the fm values are determined from the frequency table published in the applications manual for the revised niosh lifting equation ( waters et al . ,
the appropriate fm values are based on the sum of the frequencies for the task categories listed in the subscripts . in order to demonstrate how the vli method can be applied to a variable lifting job ,
a simple example of the sampling approach is provided to show how the vli equation should be applied .
remember , these 25 lifts are a representative subset of the total lifts performed by the worker during the shift .
table 1 displays the object weight , horizontal location , vertical height , vertical displacement , asymmetry angle , coupling , and calculated fili for each of the 25 sampled lifts . for simplicity
, it is assumed that significant control is not required for any of the lifts and the overall lifting frequency across the shift is three lifts per minute .
based on the measured data , it can be seen that the largest fili value sampled for any individual lift was 2.5 and the smallest fili value was 0.3 .
task data for vli hypothetical example note . a = asymmetry angle ; c = coupling quality ; d = vertical displacement ( in . ) ;
fili = frequency independent lift index ; h = horizontal distance ( in . ) ; li cat = lifting index category for vli calculation ; rwl = recommended weight limit ( lb ) ; stli = single task lifting index ; v = vertical height ( in . )
; vli = variable lifting index ; wt = object weight ( lb ) . according to the vli procedure
, the range of fili categories should be evaluated and a set of fili categories should be chosen .
this is accomplished by dividing the overall range of fili values into a fixed number of equal size categories .
the choice of fili categories is somewhat arbitrary , but we suggest choosing six categories . for this example , six fili categories were chosen . in order to determine the spans for the six categories , the difference between the maximum fili and the minimum fili is divided by the number of categories ( six ) .
thus , each category would span a range of 2.2/6 or 0.366 units on the li scale , resulting in six categories defined as 0.30.67 , 0.681.0 , 1.11.4 , 1.51.8 , 1.92.1 , and 2.22.5 .
each lift is then assigned to one of the six categories based on the magnitude of the fili values .
the representative fili value for the category containing the single task with the largest fili is assigned that maximum value ( a value of 2.5 in table 2 ) .
the representative value within each of the other categories was computed by averaging the fili values for all the sampled lifts in each of the respective categories .
the number of lifts assigned to each category and the percentage of tasks falling into each of the six cells is also shown in table 2 .
the lifting frequency for each category is determined by multiplying the percentage of lifts in each category times the overall frequency ( 3/min ) , as shown in table 2 . as with the sli approach , the vli approach works best if the job is performed for a full 8-hour shift ( waters , lu , & occhipinti , 2007 ) .
based on the data shown in table 1 , intermediate calculations for the vli example can be computed as shown in table 2 .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this example , we assumed that the overall frequency of lifting across an 8-hour shift is 3/min .
based on the data presented , the vli for this job can be calculated , as follows :
fili2=2.0((1/.84)(1/.85))=0.01
fili3=1.64((1/.77)(1/.84))=0.18
fili4=1.29((1/.68)(1/.77))=0.22
fili5=.90((1/.65)(1/.68))=0.06
fili6=.44((1/.55)(1/.65))=0.12
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.01 + 0.18 + 0.22 + 0.06 + 0.12=3.49 .
in order to demonstrate how variations in lifting frequency within the job affects the overall vli calculation , we can examine a job with the same series of lifts as previously shown but with different task frequencies .
table 3 shows data for the same job as shown in table 2 , but with different frequencies for tasks within the job . as can be seen in table 3 , the number of tasks within each li category is different , because the frequencies of the tasks are different within each category .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this alternate example , we assumed that the representative fili within each category remained the same as before :
fili2=2.0((1/.74)(1/.82))=0.26
fili3=1.64((1/.68)(1/.74))=0.20
fili4=1.29((1/.61)(1/.68))=0.22
fili5=.90((1/.58)(1/.61))=0.08
fili6=.44((1/.55)(1/.58))=0.04
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.26 + 0.20 + 0.22 + 0.08 + 0.04=3.70 .
as can be seen from this example , as the percentage of tasks with larger fili values increases , the vli value of the overall job also increases . for this example
, the increased frequencies of tasks with higher fili values increased the vli of the overall job from 3.49 to 3.7 . similarly , if the percentage of tasks with lower fili values increases , the vli for the overall job would have been lower than before .
in order to demonstrate how the vli method can be applied to a variable lifting job , a simple example of the sampling approach is provided to show how the vli equation should be applied .
remember , these 25 lifts are a representative subset of the total lifts performed by the worker during the shift .
table 1 displays the object weight , horizontal location , vertical height , vertical displacement , asymmetry angle , coupling , and calculated fili for each of the 25 sampled lifts . for simplicity
, it is assumed that significant control is not required for any of the lifts and the overall lifting frequency across the shift is three lifts per minute .
based on the measured data , it can be seen that the largest fili value sampled for any individual lift was 2.5 and the smallest fili value was 0.3 .
task data for vli hypothetical example note . a = asymmetry angle ; c = coupling quality ; d = vertical displacement ( in . ) ;
fili = frequency independent lift index ; h = horizontal distance ( in . ) ; li cat = lifting index category for vli calculation ; rwl = recommended weight limit ( lb ) ; stli = single task lifting index ; v = vertical height ( in . ) ; vli = variable lifting index ; wt = object weight ( lb ) . according to the vli procedure
, the range of fili categories should be evaluated and a set of fili categories should be chosen .
this is accomplished by dividing the overall range of fili values into a fixed number of equal size categories .
the choice of fili categories is somewhat arbitrary , but we suggest choosing six categories . for this example , six fili categories were chosen . in order to determine the spans for the six categories , the difference between the maximum fili and the minimum fili is divided by the number of categories ( six ) .
thus , each category would span a range of 2.2/6 or 0.366 units on the li scale , resulting in six categories defined as 0.30.67 , 0.681.0 , 1.11.4 , 1.51.8 , 1.92.1 , and 2.22.5 .
each lift is then assigned to one of the six categories based on the magnitude of the fili values .
the representative fili value for the category containing the single task with the largest fili is assigned that maximum value ( a value of 2.5 in table 2 ) .
the representative value within each of the other categories was computed by averaging the fili values for all the sampled lifts in each of the respective categories .
the number of lifts assigned to each category and the percentage of tasks falling into each of the six cells is also shown in table 2 . the lifting frequency for each category
is determined by multiplying the percentage of lifts in each category times the overall frequency ( 3/min ) , as shown in table 2 . as with the sli approach , the vli approach works best if the job is performed for a full 8-hour shift ( waters , lu , & occhipinti , 2007 ) .
based on the data shown in table 1 , intermediate calculations for the vli example can be computed as shown in table 2 .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this example , we assumed that the overall frequency of lifting across an 8-hour shift is 3/min .
based on the data presented , the vli for this job can be calculated , as follows :
fili2=2.0((1/.84)(1/.85))=0.01
fili3=1.64((1/.77)(1/.84))=0.18
fili4=1.29((1/.68)(1/.77))=0.22
fili5=.90((1/.65)(1/.68))=0.06
fili6=.44((1/.55)(1/.65))=0.12
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.01 + 0.18 + 0.22 + 0.06 + 0.12=3.49 .
in order to demonstrate how variations in lifting frequency within the job affects the overall vli calculation , we can examine a job with the same series of lifts as previously shown but with different task frequencies .
table 3 shows data for the same job as shown in table 2 , but with different frequencies for tasks within the job . as can be seen in table 3 , the number of tasks within each li category is different , because the frequencies of the tasks are different within each category .
fili = frequency independent lift index ; li = lifting index ; vli = variable lifting index .
for this alternate example , we assumed that the representative fili within each category remained the same as before :
fili2=2.0((1/.74)(1/.82))=0.26
fili3=1.64((1/.68)(1/.74))=0.20
fili4=1.29((1/.61)(1/.68))=0.22
fili5=.90((1/.58)(1/.61))=0.08
fili6=.44((1/.55)(1/.58))=0.04
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=2.90 + 0.26 + 0.20 + 0.22 + 0.08 + 0.04=3.70 .
as can be seen from this example , as the percentage of tasks with larger fili values increases , the vli value of the overall job also increases . for this example
, the increased frequencies of tasks with higher fili values increased the vli of the overall job from 3.49 to 3.7 . similarly ,
if the percentage of tasks with lower fili values increases , the vli for the overall job would have been lower than before .
the sampling approach , although useful in many practical situations , does present some limitations in that the task variables need to be sufficiently constant during the sampling period and limited in order to keep the representative tasks to no more than 30 . as mentioned previously ,
the systematic organizational analysis approach is based on a systematic assessment of the job using job and task data derived from methods other than sampling methods , such as production or sales data ( existing data for durations , weights , and overall and partial frequencies ) or probability distribution data ( for geometries and subpartial frequencies ) .
this assessment approach requires knowledge of the total duration of the lifting tasks during the work shift , number and weight of the different objects lifted , number of workers who do the lifting , total and partial frequency of lifts , and the work / rest pattern for the job .
all of the lifts performed by a worker are categorized into a maximum number of 30 fili values that are representative of the range of fili values that would be observed in the entire sample .
the frequencies of each of the fili values are then determined from production data ( considering weight groups ) or from probability estimates of the distributions ( considering observed geometries ) . in order to use this approach , several simplifications may be necessary , especially when many different objects are lifted with widely varying weights and geometries .
this is because , without simplifications , the number of individual fili values would be very large ( hundreds and , sometimes , thousands ) and practically impossible to manage .
one approach is to set up a simplified series of weight and geometry values from which a limited set of fili values can be derived .
the following general procedure for simplifying a large number of lifting tasks was suggested by colombini et al .
( colombini et al . , 2009 ; colombini , occhipinti , alvarez - casado , & waters , 2012 )
: 1 . compress the potential individual lifting tasks in the job into a structure that considers up to a maximum of 30 subtasks ( and corresponding fili and stli ) for different loads ( weight categories , wtcs ) and geometries using the following approach : aggregate up to 5 objects ( weights ) categories.classification of vertical location ( vertical multiplier , vm ) in only two categories ( good / bad).classification of horizontal location ( horizontal multiplier , hm ) in up to three categories ( near , mid , far).presence / absence of asymmetry ( asymmetric multiplier , am ) assessed for each wtc ( by threshold value for all the lifts in the category).daily duration of lifting classified as in the applications manual for the revised niosh lifting equation ( waters et al . , 1994).frequencies of lifts specifically determined or estimated for each subtask and fili , with fms determined as in the applications manual for the revised niosh lifting equation ( waters et al .
, 1994).vertical displacement ( vertical distance multiplier , dm ) and coupling ( coupling multiplier , cm ) are both considered as a constant .
classification of vertical location ( vertical multiplier , vm ) in only two categories ( good / bad ) .
classification of horizontal location ( horizontal multiplier , hm ) in up to three categories ( near , mid , far ) .
presence / absence of asymmetry ( asymmetric multiplier , am ) assessed for each wtc ( by threshold value for all the lifts in the category ) .
daily duration of lifting classified as in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
frequencies of lifts specifically determined or estimated for each subtask and fili , with fms determined as in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
vertical displacement ( vertical distance multiplier , dm ) and coupling ( coupling multiplier , cm ) are both considered as a constant . at the end
it will be possible to compute individual fili and stli for up to 30 subtasks .
once the selected fili values are derived , the entire set of fili values are assigned into a fixed number of fili categories .
the categories can be defined by assigning the fili values according to sextiles of the correspondent fili distribution . once the selected fili values are assigned to the appropriate category ,
the corresponding cumulative frequencies can be computed and applied using the vli concept with frequency weighting .
the study of organizational data is required for all types of lifting jobs including single - task , multitask , variable , or sequential lifting jobs .
the first assessment step is identifying the number or workers involved in manual handling activities with substantially the same task characteristics , such as weights lifted and task geometries .
then the work / rest pattern for the job has to be assessed across the shift ( i.e. , determine the sequence and relative amount of time spent performing manual lifting tasks and other nonmanual handling
activities and/or breaks ) . the various weights and relative number of objects lifted manually in a shift by one worker
first , all of the weights to be lifted are listed in a table ( for this procedure , consider weights from 3 kg up to maximum , by incremental steps of 1 kg ) .
if there are more than five different weights , the weights are aggregated into a maximum of five wtcs by dividing the span of weight values ( i.e. , max . value min . ) by 5 to determine the min . and max .
each of the individual lifts is then aggregated into those five categories , and the overall number of lifts in each category is determined .
finally , an average weight is computed for each wtc that will be used in subsequent computations .
aggregation of several weights lifted by a worker during a shift in five wtcs and computation of correspondent lifting frequency : example for weights ranging from 5 to 15 kg and for a lifting duration of 300 min in a shift from previous data such as number of workers involved in the task(s ) , net duration of manual lifting in the shift ,
total number of objects lifted during a shift , and number of objects within each wtc lifted during a shift , one can determine the overall lifting frequency ( per worker ) and the partial lifting frequency for each wtc ( as shown in table 4 for a lifting duration of 300 minutes in a shift ) .
these partial frequency values are then used in subsequent calculations , along with the appropriate lifting duration scenario ( short , medium , and long ) , to determine the appropriate fms from the traditional fm tables ( for hands height < 75 cm . )
another simplification will likely be needed to account for variability in task geometry among a large number of lifts .
provides for simplification of geometry by collapsing various factors into a small number of possible conditions , such as horizontal and vertical hand location , and task asymmetry .
the following simplifications were recommended : vertical location ( height of hands at lifting origin or destination ) : this variable is reduced to two areas : ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1.nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 .
ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1 .
nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 . in cases where the vertical height exceeds
the maximum recommended vertical height ( > 175 cm ) , the lifts would be considered unsafe . horizontal location ( maximum hand grasp point away from the body during lifting ) :
the horizontal distances were simplified into three areas near , mid , and far .
the three distances are defined as follows : near horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm).mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm).far horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . near
horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm ) . mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm ) . far
horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . in cases where the horizontal distances exceeds the maximum recommended value ( > 63 cm ) ,
asymmetry ( angular displacement of loads off to the side of the body ) : asymmetry is considered collectively for each wtc .
an am of 0.81 is assigned to all the subtasks in a wtc if asymmetry of 45 or more is observed for over 50% of lifting actions in that category .
otherwise the am is set equal to 1 . vertical travel distance ( vertical distance between the height of hands at origin and at destination ) : the contribution of this factor has been considered as noninfluent . the cm has thus been taken as a constant , equal to 1 .
it should be underlined that even if the vertical dm is set as a constant , the height of the hands at both the origin and destination of the lift should always be measured and considered .
coupling ( quality or type of grip ) : the contribution of this factor has also been defined as constant . experience has taught that
ideal couplings are very rare , so the cm is defined as a constant equal to 0.90 . by adopting the simplifications and procedures proposed by colombini et al .
( 2009 , 2012 ) , it is possible to analyze a variable lifting task scenario and produce up to ( and no more than ) 30 sets of fili and stli values , one for each of 30 different subtasks ( 5 wtcs 2 vertical location 3 horizontal areas 1 asymmetry condition ) .
after the fili subtasks are determined from the data , the subtasks will be further classified into six li categories and the vli for the overall job will be determined .
this approach is demonstrated in the example that follows . in a metal - working plant , workers load and
unload plastic containers of in - process materials to and from assembly lines for processing .
the task is organized in cycles ; during each cycle , the worker handles various containers in different body postures due to different heights ( of the hands ) at the origin and destination and different horizontal distances .
the work starts at 8 a.m. , there is a break of 10 min at 10 a.m. , and lunch time is at 1:10 p.m. ( it lasts 60 min ; out of official working time ) . in the afternoon
, the activity is the same as in the morning with a 10 min break at 3.10 p.m. and the last 40 min devoted to light work ( no manual handling ) .
table 5 shows the sequence of lifting task , breaks , and light work during the shift .
sequence and duration of lifting task , light work , and breaks for the case study in an 8-hr shift the containers have three different weights ( 6 , 8 , and 13 kg ) ; the respective number of pieces lifted during the shift is shown in table 6 .
type of weights and number of containers lifted by the worker during an 8-hour shift and consequent lifting frequency per type of weight because 1,852 containers are lifted during a 420-min period , the overall lifting frequency is 4.41 lifts per minute .
the partial lifting frequencies for each type ( weight ) of container are as follows : 1.18 lifts / min for the 6 kg containers , 2.94 lifts / min for the 8 kg containers , and 0.29 lifts / min for the 13 kg containers .
( continuous period of manual handling of 120 min + a break of only 10 min + 120 min of manual handling ) .
the lifting activities are performed at different heights ( of the hands ) at the origin and destination and different horizontal distances ; there is minimal lift asymmetry for all lifts ( i.e. , all objects are lifted in front of the body resulting in an asymmetry multiplier = 1.0 ) , and the hand - to - object coupling is poor for all lifts ( i.e. , coupling multiplier = 0.9 ) .
data regarding the geometries at the origin and destination of the lifts , by wtc , is shown in table 7 .
data regarding load and geometry characteristics in this scenario , it is not possible to use the traditional multitask lifting index ( cli ) approach , as there would be up to 50 different individual fili values ( or about 122 if one considers both origin and destination ) .
also , the mean frequency of each type of lift would be very low ( about 0.0300.036 lifts / min ) .
because the traditional cli approach can not work , the proposed vli approach , using weight and geometry simplifications , should be used to assess the task . in the presented example
, we have only three wtcs ( 6 , 8 , and 13 kg ) ; each of them could have two simplified
( good and bad ) at origin / destination ; in turn , each of them could have one , two , or three simplified
because different horizontal distances per wtcs are clearly identified both at origin than at destination , it results in a total of 14 individual subtasks , as shown in table 8 .
table 8 also displays the corresponding weights , geometries , partial frequency , and fm , fili , and stli values for each of the 14 identified subtasks .
data regarding the 14 resulting subtasks ( and corresponding fili and stli ) by applying the simplifications and the frequency estimation procedures note . a = absent ; cm = coupling multiplier ; dm = distance multiplier ; f = far ; fili = frequency independent lift index ; firwl = frequency independent recommended weight limit ; fm = frequency multiplier ; g = good ; hm = horizontal multiplier ; ld = long duration ; l / h = low or high ; m = medium ; n = near ; p = poor ; stli = single task lifting index ; vm = vertical multiplier . for determining partial frequencies of individual subtasks , a special procedure has been adopted that takes into account , for each wtc , how many times the height of hands starts or ends , respectively , in a
area , considering small height intervals of 10 cm and then considering how many times each height of hands
( good and bad ) at origin / destination corresponds to different variants for horizontal distance ( near , mid , and far ) both at origin and at destination .
this procedure is a little more complicated than simply assigning an equal frequency to all the combinations present in a wtc , but assisted by proper software , it is a better estimate of the different frequencies in different geometries combinations in a certain category .
for example , for the 6 kg category , we could consider as equally represented all the six possible combinations ( height of hands , good / bad ; horizontal distance , near / mid / far ) and consequently dividing the overall wtc frequency of 1.18 by 6 , thus obtaining partial frequencies for each combination of 0.196 .
however , it is preferable to adopt the more detailed procedure to obtain more accurate estimates of the partial frequencies of individual combinations . using this procedure , we have that four of nine lifts ( 44.4% ) originate or end in a bad vertical height ( l / h vertical height ) and the other five ( 55.6% ) are in the good vertical height category .
for the bad vertical height category , the lifts will be equally distributed with regard to horizontal reach ( i.e. , one third of the lifts will be near , one third mid , and one third far reaches ) , whereas for the good vertical height category we have one half of the lifts in a near horizontal reach and one fourth , respectively , in the mid and far reach categories . therefore , for the combinations l / h - near , l / h - mid , and l / h - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result always of about 14.8% each ; because the overall frequency of lifts in the 6 kg category is 1.180 lifts per minute , we have for each combination a partial frequency of about 0.175 lifts per minute . for the combinations of good - near , good - mid , and good - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result , respectively , in 27.8% , 13.9% , and 13.9% and the corresponding partial frequencies are 0.328 , 0.164 , and 0.164 .
for the other wtcs , a similar approach has been used to determine individual tasks partial frequencies .
the resulting frequencies of lifts for the various combinations ( 14 in the present example ) of vertical height and horizontal reaches are reported in table 8 . because 14 subtasks are still too many to use directly the cli formula
, it is advisable to use the vli concept and approach . to apply the vli approach , subtasks and corresponding
data ( fili , frequencies , and stli ) are distributed into six li categories .
those six categories are determined according to the distribution of the individual fili values ( in this case 14 values ) using preferentially the sextile distributions as key points for grouping ( or in other terms the values corresponding to the 16.6th , 33.3rd , 50th , 66.6th , and 83.3rd percentile of the resulting fili distribution ) . as a simpler alternative
, one may obtain six key points by dividing the range of fili values ( i.e. , maximum fili
minimum fili ) divided by 6 ; this simpler option has , however , some disadvantages ( i.e. , some li category could be empty ; the distribution of fili values could be not well represented ) . in any case , the original frequencies of individual subtasks ( 14 in present case ) are grouped and cumulated in the six li categories . single ( category ) li values could be consequently computed and used for reordering ( from highest to lowest ) the six li categories . within each resulting li category , a representative fili value is chosen : this value is the highest for the highest category ( category number 1 ) ; it corresponds to the mean ( central ) value for all the other five li categories .
relevant values for each fili category using the key points from table 9 and the consequent cumulated frequencies derived from table 8 note .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index . using these data , organized in six fili categories
, it will be possible to compute the vli by means of the traditional cli formula in the same way previously reported for the task sampling approach .
based on the data presented for this example , the computational data for applying the formula vli = stli1 + li are reported in table 11 .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index ; vli = variable lifting index . using data reported in table 11 ,
the vli for this job can be calculated , as follows :
fili2=0.907*[(1/0.698)(1/0.748)])=0.907*(0.096)=0.087
fili3=0.805*[(1/0.672)(1/0.698)]=0.805*(0.055)=0.045
fili4=0.694*[(1/0.590)(1/0.672)]=0.694*(0.207)=0.144
fili5=0.604*[(1/0.475)(1/0.590)]=0.604*(0.410)=0.248
fili6=0.483*[(1/0.409)(1/0.475)]=0.483*(0.340)=0.164
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=1.656 + 0.087 + 0.045 + 0.144 + 0.248 + 0.164=2.34 .
the study of organizational data is required for all types of lifting jobs including single - task , multitask , variable , or sequential lifting jobs .
the first assessment step is identifying the number or workers involved in manual handling activities with substantially the same task characteristics , such as weights lifted and task geometries .
then the work / rest pattern for the job has to be assessed across the shift ( i.e. , determine the sequence and relative amount of time spent performing manual lifting tasks and other nonmanual handling
activities and/or breaks ) . the various weights and relative number of objects lifted manually in a shift by one worker
first , all of the weights to be lifted are listed in a table ( for this procedure , consider weights from 3 kg up to maximum , by incremental steps of 1 kg ) .
if there are more than five different weights , the weights are aggregated into a maximum of five wtcs by dividing the span of weight values ( i.e. , max . value min . ) by 5 to determine the min . and max .
each of the individual lifts is then aggregated into those five categories , and the overall number of lifts in each category is determined .
finally , an average weight is computed for each wtc that will be used in subsequent computations .
aggregation of several weights lifted by a worker during a shift in five wtcs and computation of correspondent lifting frequency : example for weights ranging from 5 to 15 kg and for a lifting duration of 300 min in a shift from previous data such as number of workers involved in the task(s ) , net duration of manual lifting in the shift ,
total number of objects lifted during a shift , and number of objects within each wtc lifted during a shift , one can determine the overall lifting frequency ( per worker ) and the partial lifting frequency for each wtc ( as shown in table 4 for a lifting duration of 300 minutes in a shift ) .
these partial frequency values are then used in subsequent calculations , along with the appropriate lifting duration scenario ( short , medium , and long ) , to determine the appropriate fms from the traditional fm tables ( for hands height < 75 cm . )
another simplification will likely be needed to account for variability in task geometry among a large number of lifts .
provides for simplification of geometry by collapsing various factors into a small number of possible conditions , such as horizontal and vertical hand location , and task asymmetry .
the following simplifications were recommended : vertical location ( height of hands at lifting origin or destination ) : this variable is reduced to two areas : ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1.nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 .
ideal area ( good ) : hands are between 51 and 125 cm vertical height ; the vm is equal to 1 .
nonideal areas ( low or high ) : hands are equal or below 50 cm or above 125 cm ( up to 175 cm ) vertical height ; the vm is equal to 0.78 . in cases where the vertical height exceeds
the maximum recommended vertical height ( > 175 cm ) , the lifts would be considered unsafe .
horizontal location ( maximum hand grasp point away from the body during lifting ) : the horizontal distances were simplified into three areas near , mid , and far .
the three distances are defined as follows : near horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm).mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm).far horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . near
horizontal distance is within 2540 cm ; the representative hm is equal to 0.71 ( for a representative value of 35 cm ) . mid horizontal distance is within 4150 cm ; the representative hm is equal to 0.56 ( for a representative value of 45 cm ) . far
horizontal distance is within 5163 cm ; the representative hm is equal to 0.40 ( for a representative value of 63 cm ) . in cases where the horizontal distances exceeds the maximum recommended value ( > 63 cm ) ,
asymmetry ( angular displacement of loads off to the side of the body ) : asymmetry is considered collectively for each wtc .
an am of 0.81 is assigned to all the subtasks in a wtc if asymmetry of 45 or more is observed for over 50% of lifting actions in that category .
otherwise the am is set equal to 1 . vertical travel distance ( vertical distance between the height of hands at origin and at destination ) : the contribution of this factor has been considered as noninfluent . the cm has thus been taken as a constant , equal to 1 . it should be underlined that even if the vertical dm is set as a constant , the height of the hands at both the origin and destination of the lift should always be measured and considered . coupling ( quality or type of grip ) : the contribution of this factor has also been defined as constant .
ideal couplings are very rare , so the cm is defined as a constant equal to 0.90 . by adopting the simplifications and procedures proposed by colombini et al .
( 2009 , 2012 ) , it is possible to analyze a variable lifting task scenario and produce up to ( and no more than ) 30 sets of fili and stli values , one for each of 30 different subtasks ( 5 wtcs 2 vertical location 3 horizontal areas 1 asymmetry condition ) .
after the fili subtasks are determined from the data , the subtasks will be further classified into six
in a metal - working plant , workers load and unload plastic containers of in - process materials to and from assembly lines for processing .
the task is organized in cycles ; during each cycle , the worker handles various containers in different body postures due to different heights ( of the hands ) at the origin and destination and different horizontal distances .
the work starts at 8 a.m. , there is a break of 10 min at 10 a.m. , and lunch time is at 1:10 p.m. ( it lasts 60 min ; out of official working time ) . in the afternoon , the activity is the same as in the morning with a 10 min break at 3.10 p.m. and the last 40 min devoted to light work ( no manual handling ) .
table 5 shows the sequence of lifting task , breaks , and light work during the shift .
sequence and duration of lifting task , light work , and breaks for the case study in an 8-hr shift the containers have three different weights ( 6 , 8 , and 13 kg ) ; the respective number of pieces lifted during the shift is shown in table 6 .
type of weights and number of containers lifted by the worker during an 8-hour shift and consequent lifting frequency per type of weight because 1,852 containers are lifted during a 420-min period , the overall lifting frequency is 4.41 lifts per minute .
the partial lifting frequencies for each type ( weight ) of container are as follows : 1.18 lifts / min for the 6 kg containers , 2.94 lifts / min for the 8 kg containers , and 0.29 lifts / min for the 13 kg containers .
( continuous period of manual handling of 120 min + a break of only 10 min + 120 min of manual handling ) .
the lifting activities are performed at different heights ( of the hands ) at the origin and destination and different horizontal distances ; there is minimal lift asymmetry for all lifts ( i.e. , all objects are lifted in front of the body resulting in an asymmetry multiplier = 1.0 ) , and the hand - to - object coupling is poor for all lifts ( i.e. , coupling multiplier = 0.9 ) . a significant control is present for quite all lifting actions .
data regarding the geometries at the origin and destination of the lifts , by wtc , is shown in table 7 .
data regarding load and geometry characteristics in this scenario , it is not possible to use the traditional multitask lifting index ( cli ) approach , as there would be up to 50 different individual fili values ( or about 122 if one considers both origin and destination )
. also , the mean frequency of each type of lift would be very low ( about 0.0300.036 lifts / min ) .
because the traditional cli approach can not work , the proposed vli approach , using weight and geometry simplifications , should be used to assess the task . in the presented example , we have only three wtcs ( 6 , 8 , and 13 kg ) ; each of them could have two simplified
( good and bad ) at origin / destination ; in turn , each of them could have one , two , or three simplified variants for horizontal distance ( near , mid , and far ) . because different horizontal distances per wtcs are clearly identified both at origin than at destination , it results in a total of 14 individual subtasks , as shown in table 8 .
table 8 also displays the corresponding weights , geometries , partial frequency , and fm , fili , and stli values for each of the 14 identified subtasks .
data regarding the 14 resulting subtasks ( and corresponding fili and stli ) by applying the simplifications and the frequency estimation procedures note . a = absent ; cm = coupling multiplier ; dm = distance multiplier ; f = far ; fili = frequency independent lift index ; firwl = frequency independent recommended weight limit ; fm = frequency multiplier ; g = good ; hm = horizontal multiplier ; ld = long duration ; l / h = low or high ; m = medium ; n = near ; p = poor ; stli = single task lifting index ; vm = vertical multiplier . for determining partial frequencies of individual subtasks , a special procedure has been adopted that takes into account , for each wtc , how many times the height of hands starts or ends , respectively , in a
good or bad area , considering small height intervals of 10 cm and then considering how many times each height of hands
( good and bad ) at origin / destination corresponds to different variants for horizontal distance ( near , mid , and far ) both at origin and at destination .
this procedure is a little more complicated than simply assigning an equal frequency to all the combinations present in a wtc , but assisted by proper software , it is a better estimate of the different frequencies in different geometries combinations in a certain category .
for example , for the 6 kg category , we could consider as equally represented all the six possible combinations ( height of hands , good / bad ; horizontal distance , near / mid / far ) and consequently dividing the overall wtc frequency of 1.18 by 6 , thus obtaining partial frequencies for each combination of 0.196 .
however , it is preferable to adopt the more detailed procedure to obtain more accurate estimates of the partial frequencies of individual combinations . using this procedure
, we have that four of nine lifts ( 44.4% ) originate or end in a bad vertical height ( l / h vertical height ) and the other five ( 55.6% ) are in the good vertical height category . for the bad vertical height category
, the lifts will be equally distributed with regard to horizontal reach ( i.e. , one third of the lifts will be near , one third mid , and one third far reaches ) , whereas for the good vertical height category we have one half of the lifts in a near horizontal reach and one fourth , respectively , in the mid and far reach categories .
therefore , for the combinations l / h - near , l / h - mid , and l / h - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result always of about 14.8% each ; because the overall frequency of lifts in the 6 kg category is 1.180 lifts per minute , we have for each combination a partial frequency of about 0.175 lifts per minute . for the combinations of good - near , good - mid , and good - far , the prevalence ( with respect to all the 6 kg lifts ) of lifts result , respectively , in 27.8% , 13.9% , and 13.9% and the corresponding partial frequencies are 0.328 , 0.164 , and 0.164 .
for the other wtcs , a similar approach has been used to determine individual tasks partial frequencies .
the resulting frequencies of lifts for the various combinations ( 14 in the present example ) of vertical height and horizontal reaches are reported in table 8 . because 14 subtasks are still too many to use directly the cli formula
, it is advisable to use the vli concept and approach . to apply the vli approach , subtasks and corresponding data ( fili , frequencies , and stli )
those six categories are determined according to the distribution of the individual fili values ( in this case 14 values ) using preferentially the sextile distributions as key points for grouping ( or in other terms the values corresponding to the 16.6th , 33.3rd , 50th , 66.6th , and 83.3rd percentile of the resulting fili distribution ) . as a simpler alternative
, one may obtain six key points by dividing the range of fili values ( i.e. , maximum fili
minimum fili ) divided by 6 ; this simpler option has , however , some disadvantages ( i.e. , some li category could be empty ; the distribution of fili values could be not well represented ) . in any case , the original frequencies of individual subtasks ( 14 in present case ) are grouped and cumulated in the six li categories . single ( category ) li values could be consequently computed and used for reordering ( from highest to lowest ) the six li categories . within each resulting li category , a representative fili value is chosen : this value is the highest for the highest category ( category number 1 ) ; it corresponds to the mean ( central ) value for all the other five li categories .
identification of key points by the sextile approach using the fili data distribution from table 8 note .
relevant values for each fili category using the key points from table 9 and the consequent cumulated frequencies derived from table 8 note .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index . using these data , organized in six fili categories ,
it will be possible to compute the vli by means of the traditional cli formula in the same way previously reported for the task sampling approach .
based on the data presented for this example , the computational data for applying the formula vli = stli1 + li are reported in table 11 .
fili = frequency independent lift index ; fm = frequency multiplier ; stli = single task lifting index ; vli = variable lifting index .
using data reported in table 11 , the vli for this job can be calculated , as follows :
fili2=0.907*[(1/0.698)(1/0.748)])=0.907*(0.096)=0.087
fili3=0.805*[(1/0.672)(1/0.698)]=0.805*(0.055)=0.045
fili4=0.694*[(1/0.590)(1/0.672)]=0.694*(0.207)=0.144
fili5=0.604*[(1/0.475)(1/0.590)]=0.604*(0.410)=0.248
fili6=0.483*[(1/0.409)(1/0.475)]=0.483*(0.340)=0.164
vli = stli1+fili2+fili3+fili4+fili5+fili6
vli=1.656 + 0.087 + 0.045 + 0.144 + 0.248 + 0.164=2.34 .
the scientific basis for the vli procedure is similar to that for the cli originally presented by niosh in the applications manual for the revised niosh lifting equation ( waters et al . , 1994 ) .
the cli was based on the assumption that the physical stress for a multitask manual lifting job with multiple lifting tasks would be greater than the physical stress for the task element with the greatest single stli and that the overall physical stress would increase as additional tasks were added to the job .
thus , the cli started with the task with the greatest single stli and then each successive task was added into the cli calculation based on increasing fili value .
the frequency adjustments were added into the formula during the final summation of the physical stress measure to account for the physiological demand of the job that would result from the frequency and duration of the overall job . the scientific logic for the vli as an assessment method should be similar to that for the cli and sli methods that have previously been proposed by niosh development teams ( waters et al . , 1994
the exact cut - off or threshold values used with the categorization strategy remains problematic with the rnle .
the fili measure for each task in a multitask job was designed to provide some idea about what the biomechanical risk for the task would be independent of the other tasks being performed or their frequencies . in this way
, the user would be able to identify those job tasks that would be best addressed by adjusting the job characteristics to maximize the reduction in biomechanical stress .
the difference is that a specific set of job categories are created to allow inclusion of all the lifts in order to emulate the individual tasks in the cli procedure . rather than use specific values for the fili , each job category
is composed of a range of fili values that correspond to a level of biomechanical stress . from this perspective , individual lifts with high physical demands can not be identified , but categories containing tasks with the highest physical demands would likely be identified from the vli analysis . in this way , two distinct jobs with variable task characteristics can be compared and the categories with the highest physical demand can be identified and adjusted by reducing exposure to those tasks comprising the category with the highest physical demand as determined from the vli analysis .
the question may arise as to the handling of tasks where the measured task parameters are outside of the allowable range ( e.g. , a horizontal distance beyond 63 cm or a vertical height above 175 cm ) . in this case
, the particular task should be defined as critical with the suggestion that an urgent redesign intervention is needed . as a second option , the analyst may choose to use the maximum multiplier for the parameter ( e.g. , the hm of 0.4 for a 63 cm horizontal distance used for horizontal distances greater than 63 cm ) , with the understanding that the risk may be underestimated .
in these types of cases , the analyst may also consider supplementing the rnle analysis with other analysis methods .
the vli method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift .
the vli can also provide an overall assessment of the physical demands for manual lifting jobs performed in environments where traditionally it has been difficult to assess . as with the previous sli method ( waters et al . , 2007 ) , it is critical that the vli method is validated using an epidemiological approach to investigate the association between li ( cli and vli ) values and health outcomes .
the preliminary results of such a study are presented in this special issue ( battevi , pandolfi , & cortinovis , 2016 ) .
variable lifting task is defined as a lifting task in which both the load displacement / geometry and load mass vary in different lifts performed by the worker(s ) during the same period of time ( i.e. , an 8-hour shift ) . a variable lifting task is often observed in industry , warehousing , baggage handling , construction , and several service jobs , but a procedure for analyzing variable lifting tasks has not been previously defined by niosh . a procedure for computing the vli , based on adaptations of the rnle and of the composite lifting index approach is presented as a practical tool for analyzing variable lifting tasks . the procedure is aimed at compressing a potential high number of individual lifting indexes to a restricted number to better apply the cli formula .
there are two different approaches for obtaining the data needed to apply the vli procedure : the sampling approach and the systematic organizational analysis approach .
the vli approach is now addressed by international organization for standardization ( iso ) technical report ( tr ) 12295 as a practical tool for the application of the iso standard 11228 - 1 .
free downloadable software are available at www.epmresearch.org to apply the procedure and compute the vli . | objective : we seek to develop a new approach for analyzing the physical demands of highly variable lifting tasks through an adaptation of the revised niosh ( national institute for occupational safety and health ) lifting equation ( rnle ) into a variable lifting index ( vli).background : there are many jobs that contain individual lifts that vary from lift to lift due to the task requirements .
the niosh lifting equation is not suitable in its present form to analyze variable lifting tasks.method:in extending the prior work on the vli , two procedures are presented to allow users to analyze variable lifting tasks .
one approach involves the sampling of lifting tasks performed by a worker over a shift and the calculation of the frequency independent lift index ( fili ) for each sampled lift and the aggregation of the fili values into six categories . the composite lift index ( cli ) equation is used with lifting index ( li ) category frequency data to calculate the vli .
the second approach employs a detailed systematic collection of lifting task data from production and/or organizational sources .
the data are organized into simplified task parameter categories and further aggregated into six fili categories , which also use the cli equation to calculate the vli.results:the two procedures will allow practitioners to systematically employ the vli method to a variety of work situations where highly variable lifting tasks are performed.conclusions:the scientific basis for the vli procedure is similar to that for the cli originally presented by niosh ; however , the vli method remains to be validated.application:the vli method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift . |
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