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SECTION 1. SHORT TITLE. This Act may be cited as the ``Great Lakes Restoration Initiative Act of 2014''. SEC. 2. GREAT LAKES RESTORATION INITIATIVE. Section 118(c) of the Federal Water Pollution Control Act (33 U.S.C. 1268(c)) is amended by striking paragraph (7) and inserting the following: ``(7) Great lakes restoration initiative.-- ``(A) Establishment.--There is established in the Agency a Great Lakes Restoration Initiative (referred to in this paragraph as the `Initiative') to carry out programs and projects for Great Lakes protection and restoration. ``(B) Focus areas.--The Initiative shall prioritize programs and projects carried out in coordination with non-Federal partners and programs and projects that address priority areas each fiscal year, including-- ``(i) the remediation of toxic substances and areas of concern; ``(ii) the prevention and control of invasive species and the impacts of invasive species; ``(iii) the protection and restoration of nearshore health and the prevention and mitigation of nonpoint source pollution; ``(iv) habitat and wildlife protection and restoration, including wetlands restoration and preservation; and ``(v) accountability, monitoring, evaluation, communication, and partnership activities. ``(C) Projects.--Under the Initiative, the Agency shall collaborate with Federal partners, including the Great Lakes Interagency Task Force, to select the best combination of programs and projects for Great Lakes protection and restoration using appropriate principles and criteria, including whether a program or project provides-- ``(i) the ability to achieve strategic and measurable environmental outcomes that implement the Great Lakes Action Plan and the Great Lakes Water Quality Agreement; ``(ii) the feasibility of-- ``(I) prompt implementation; ``(II) timely achievement of results; and ``(III) resource leveraging; and ``(iii) the opportunity to improve interagency and inter-organizational coordination and collaboration to reduce duplication and streamline efforts. ``(D) Implementation of projects.-- ``(i) In general.--Funds made available to carry out the Initiative shall be used to strategically implement-- ``(I) Federal projects; and ``(II) projects carried out in coordination with States, Indian tribes, municipalities, institutions of higher education, and other organizations. ``(ii) Transfer of funds.--With amounts made available for the Initiative each fiscal year, the Administrator may-- ``(I) transfer not more than $300,000,000 to the head of any Federal department or agency, with the concurrence of the department or agency head, to carry out activities to support the Initiative and the Great Lakes Water Quality Agreement; and ``(II) enter into an interagency agreement with the head of any Federal department or agency to carry out activities described in subclause (I). ``(E) Scope.-- ``(i) In general.--Projects shall be carried out under the Initiative on multiple levels, including-- ``(I) Great Lakes-wide; and ``(II) Great Lakes basin-wide. ``(ii) Limitation.--No funds made available to carry out the Initiative may be used for any water infrastructure activity (other than a green infrastructure project that improves habitat and other ecosystem functions in the Great Lakes) for which amounts are made available from-- ``(I) a State water pollution control revolving fund established under title VI; or ``(II) a State drinking water revolving loan fund established under section 1452 of the Safe Drinking Water Act (42 U.S.C. 300j-12). ``(F) Activities by other federal agencies.--Each relevant Federal department or agency shall, to the maximum extent practicable-- ``(i) maintain the base level of funding for the Great Lakes activities of that department or agency without regard to funding under the Initiative; and ``(ii) identify new activities and projects to support the environmental goals of the Initiative. ``(G) Funding.--There is authorized to be appropriated to carry out the Initiative $300,000,000 for each of fiscal years 2015 through 2019.''. Passed the House of Representatives December 9, 2014. Attest: KAREN L. HAAS, Clerk.

. Great Lakes Restoration Initiative Act of 2014 - Amends the Federal Water Pollution Control Act (commonly known as the Clean Water Act) to authorize the Environmental Protection Agency's Great Lakes Restoration Initiative for FY2015-FY2019. Requires that the Initiative carry out programs and projects for Great Lakes protection and restoration. Directs the Initiative to prioritize programs and projects, including: the remediation of toxic substances and areas of concern; the prevention and control of invasive species and their impacts; the protection and restoration of near-shore health and the prevention and mitigation of nonpoint source pollution (water pollution that comes from many diffuse sources, such as pollution on the ground picked up by rain or snow); habitat and wildlife protection and restoration; and accountability, monitoring, evaluation, communication, and partnership activities. Prohibits funding made available to implement the Initiative from being used for any water infrastructure activity (other than a green infrastructure project that improves habitat and other ecosystem functions in the Great Lakes) for which funding is made available under the clean water or drinking water state revolving fund program. Requires federal agencies to maintain the base level of funding for their Great Lakes activities without regard to funding under the Initiative and identify new activities to support the environmental goals of the Initiative.

gastric volvulus is defined as rotation of the stomach or part of the stomach by more than 180 creating a closed - loop obstruction . the most common type in adults is the organoaxial type , which means that the stomach rotates along the longitudinal axis . acute intrathoracic gastric volvulus occurs when the stomach undergoes organoaxial torsion in the chest due to either concomitant enlargement of the hiatus or a diaphragmatic hernia . an iatrogenic diaphragmatic hernia can occur following surgical procedures , such as left nephrectomy , esophagogastrectomy and splenopancreatectomy , although it most frequently develops after hiatal hernia repair by either the nissen or the allison techniques . the common symptoms of intrathoracic stomach are postprandial chest discomfort , dysphagia , vomiting , hemorrhage , chest fullness , inability to belch , and anemia ; reflux alone is uncommon , and the signs and symptoms of acute gastric volvulus include abdominal pain and distention , especially in the upper abdomen , and vomiting with progression to nonproductive retching . it is traditionally diagnosed by seeing intrathoracic viscera in the chest radiograph ; this can be followed by a barium contrast study or upper gastrointestinal endoscopy . currently , computed tomography ( ct ) scan can lead to an immediate diagnosis with all the anatomical details . this disease is potentially life - threatening as delayed diagnosis and treatment may result in perforation , infarction or other lethal insults . due to its rarity , however , an individual physician who has no personal experience with this disease can potentially misdiagnose it as a nonsurgical gastrointestinal disease . here , we describe a rare complication of gynecologic surgery , an acute intrathoracic gastric volvulus due to diaphragmatic hernia occurring in a middle - aged woman who underwent total adnexal hysterectomy , salpingo - oophorectomy , omentectomy and splenectomy for treatment of cervical cancer one year earlier . a 49-year - old woman presented to our emergency department with a one - day history of acute moderate epigastric soreness and vomiting . she had undergone total adnexal hysterectomy and salpingo - oophorectomy secondary to cervical cancer one year previously ; omentectomy and splenectomy had also been performed . following these operations , she had completed 9-cycle chemotherapy and had visited our hospital regularly . upon arrival in the emergency department , her blood pressure was 110/85 mm hg , heart rate was 130 beats per minute , respiratory rate was 15 times per minute , and body temperature was 36.8c . initial laboratory results were as follows : white blood cell count 7,600/l with 41% segmented neutrophils , blood urea nitrogen 20 mg / dl , creatinine 0.5 mg / dl , amylase 38 iu / l , lipase 10 iu / l and c - reactive protein 0.53 mg / l . in contrast to a chest radiograph made three months earlier , the chest radiograph obtained in the emergency department demonstrated an elevated gastric air - fluid level in the left lower lung field ( fig . , this finding was regarded as an eventration of the diaphragm with the stomach present under the diaphragm . as the patient complained of vomiting and epigastric soreness , an urgent gastroduodenoscopy was performed . gastroscopy demonstrated massive fluid collection just below the gastroesophageal junction and pseudo - obstruction due to a structural abnormality of the stomach body ( fig . a chest ct scan demonstrated the distended stomach , located in the left lower hemithorax through a left diaphragmatic defect ( fig . the stomach was found in the left lower thorax with adhesions among the diaphragm , herniated stomach and left lower lobe of the lung . the herniated stomach was reduced into the abdomen , and the diaphragm was repaired following lysing of adhesions . postoperative recovery was uneventful , and the patient did not experience any pain or difficulty with eating . acute gastric volvulus is a rare disease that requires a high index of suspicion for diagnosis and rapid treatment . the signs and symptoms of gastric volvulus depend on the rapidity of onset and the degree of rotation and obstruction . this disease is potentially life - threatening because delayed diagnosis and treatment may lead to perforation , infarction or other lethal insults . because of the rarity of this disease , common gastrointestinal complaints may lead the physician to misdiagnose this as a nonsurgical gastrointestinal disease if detailed history and physical examination are not obtained . the classic triad described by borchardt of retching , severe and constant epigastric pain , and difficulty in inserting a nasogastric tube suggests an acute gastric volvulus . traditionally , it is diagnosed by observation of intrathoracic viscera on chest radiograph , followed by a barium contrast study or upper gastrointestinal endoscopy . when our patient presented to the emergency unit , a chest radiograph may have demonstrated diaphragmatic hernia , but this was interpreted as the stomach being elevated with eventration of the diaphragm , leading to the misdiagnosis of the stomach being present under the diaphragm . we entertained the possibility of a gastric volvulus after gastroscopy and demonstrated a twisted stomach . a chest ct scan was then obtained to evaluate for intrathoracic gastric volvulus with diaphragmatic hernia . a ct scan can lead to an immediate diagnosis , given its level of anatomical detail . upon ct , the stomach in an unusually high position or with an abnormal axis in a patient with acute abdominal pain and vomiting should make one suspect gastric volvulus . in our case , the fundus was in the thoracic cavity , and the body of the stomach was extremely twisted . when the fundus was rotated back into the abdominal cavity , it caused a closed loop and acute volvulus of the stomach . surgery is mandatory whenever a diagnosis of diaphragmatic injury or acute volvulus is made [ 5 , 12 ] . iatrogenic diaphragmatic hernia can occur following surgical procedures , such as left nephrectomy , esophagogastrectomy and splenopancreatectomy , although it most frequently develops after hiatal hernia repair by either the nissen or the allison techniques . the patient had undergone extensive abdominal operations : total adnexal hysterectomy , salpingo - oophorectomy , omentectomy and splenectomy for treatment of cervical cancer one year earlier . we assume that at that time a small and intraoperatively unrecognized injury of the diaphragm occurred . during the ensuing period , this laceration enlarged progressively , likely due to the observed adhesions , with resulting traction on the diaphragm [ 13 , 14 , 15 , 16 ] . following this , acute intrathoracic gastric volvulus due to iatrogenic diaphragmatic hernia is a rare complication of thoracic and abdominal surgery . therefore , it is difficult for a physician to diagnose it without prior personal experience . a delay in its diagnosis and treatment can have fatal consequences , such as gastric ischemia , perforation and hemorrhage . considering these serious complications , we can not overemphasize the importance of a detailed history , physical examination , and obtaining a delicate chest radiograph interpretation when the physician is faced with a patient presenting with vomiting and abdominal pain following abdominal or thoracic surgery .

acute intrathoracic gastric volvulus occurs when the stomach undergoes organoaxial torsion in the chest due to either concomitant enlargement of the hiatus or a diaphragmatic hernia . iatrogenic diaphragmatic hernia can occur after hiatal hernia repair and other surgical procedures , such as nephrectomy , esophagogastrectomy and splenopancreatectomy . we describe a 49-year - old woman who presented to our emergency department with acute moderate epigastric soreness and vomiting . she had undergone extensive gynecologic surgery including splenectomy 1 year before . the chest radiograph obtained in the emergency department demonstrated an elevated gastric air - fluid level in the left lower lung field . an urgent gastroscopy showed twisted structural abnormality of the stomach body . a computed tomography scan demonstrated the distended stomach , located in the left lower hemithorax through a left diaphragmatic defect . emergent transthoracic repair was performed . postoperative recovery was uneventful , and the patient did not experience any pain or difficulty with eating .

for a smooth , projective curve @xmath4 with a choice @xmath5 of marked points , and an assignment @xmath6 of parabolic subgroups @xmath7 to these points , a quasi - parabolic principal bundle of type @xmath8 is a principal bundle @xmath9 on @xmath10 and a choice @xmath11_{p_i}$ ] from the fiber of the @xmath12 associated bundle at the marked point @xmath13 . the moduli stacks @xmath14 of these objects have been widely studied due to their place in algebraic geometry as a generalization to the jacobian variety , and because of their relationship to conformal field theory and representation theory , which we will describe further below . in @xcite we began a program to study these stacks by describing the algebras formed by the global sections of their line bundles , sometimes called non - abelian theta functions . our primary object of interest is the algebra formed by all of the non - abelian theta functions , obtained by endowing the direct sum of all global sections of line bundles on the stack with global section multiplication . this algebra is known as the cox ring or total coordinate ring of the stack @xmath14 . in this paper we describe this algebra in a special case @xmath15 where the curve @xmath10 is a projective line , and the parabolic structure at each marked point is given by the stabilizers @xmath16 of the highest weight vector in the representation @xmath1 or its dual @xmath2 . we let @xmath17 be the number of marked points with parabolic data @xmath18 and @xmath19 be the number of marked points with parabolic data @xmath20 line bundles @xmath21 on this stack are indexed by a tuple @xmath22 of @xmath17 non - negative integers , a tuple @xmath23 of @xmath19 non - negative integers , and a non - negative integer @xmath24 called the level . @xmath25 @xmath26 by definition the algebra @xmath27 contains each of the projective coordinate rings @xmath28 defined by the line bundle @xmath29 as a graded subalgebra . we prove the following theorem . [ main ] for generic arrangements of points @xmath30 the algebra @xmath27 is minimally generated by the non - abelian theta functions with @xmath31 the relations which hold among these generators are generated by the quadratic relations . in the case @xmath32 the parabolic subgroups @xmath33 are equal , in this case we set @xmath34 . this case is studied by castravet and tevelev in @xcite , where the algebra @xmath35 is shown to be a cox - nagata ring . this means that @xmath35 is the algebra of invariants by a certain non - reductive ( additive ) group action on a polynomial ring , and can be identified with the cox ring of a blow - up of a projective space . sturmfels and xu also study this case in @xcite , where they construct a sagbi ( subalgebra analogue of grbner bases for ideals ) degeneration @xmath36 of @xmath35 for generic @xmath37 , for each trivalent tree @xmath38 with @xmath39 leaves . the degenerations @xmath36 constructed in @xcite are notable as they are affine semigroup algebras which have also been studied by buczyska and winiewski @xcite in the context of mathematical biology . the algebras @xmath36 are the coordinate rings of the @xmath40 group - based phylogenetic statistical models . generators for the ideal of relations presenting these coordinate rings are important for applications of these models , to that end buczyska and winiewski prove results for @xmath36 which imply theorem [ main ] in the @xmath41 case , via the degeneration techniques in @xcite . in this paper we also employ degeneration methods , developed in @xcite from elements of conformal field theory ( see below ) . the tree combinatorics is still present , however it stems from a relationship to the moduli of marked genus @xmath42 curves @xmath43 rather than a sagbi construction . it would be interesting to find a sagbi construction for @xmath27 in the general case , and also an interpretation of this algebra as the invariants of an additive group action on a polynomial ring . we choose the standard set of positive roots @xmath44 for @xmath0 , with corresponding weyl chamber @xmath45 dominant weights @xmath46 of @xmath0 and positive dominant weights of @xmath47 in this weyl chamber are weakly descreasing lists of @xmath48 and @xmath49 numbers , respectively . @xmath50\\\ ] ] we let @xmath51 denote the irreducible representation corresponding to a dominant weight @xmath52 the fundamental weight @xmath53 is the list with @xmath54 @xmath55s followed by @xmath56 @xmath57s , and its corresponding irreducible represention is the exterior product @xmath58 note that @xmath59 is the determinant representation of @xmath47 and therefore the trivial representation of @xmath60 in order to prove theorem [ main ] , we first degenerate @xmath27 to an affine semigroup algebra , using theorem @xmath61 in @xcite . when specialized to the case we consider here , this theorem says that for any trivalent tree @xmath38 with @xmath62 labelled leaves , there is a degeneration of @xmath27 to an algebra @xmath63 . the algebra @xmath63 is built out of the total coordinate rings of moduli of @xmath0 quasi - parabolic principal bundles on a triple marked projective line , @xmath64 according to a specific recipe dictated by @xmath65 the structure of @xmath63 depends on the tree @xmath66 so it is critical to choose a tree topology which gives an algebra with advantageous properties . from now on , we consider the `` caterpillar '' tree @xmath67 , depicted in figure [ cat ] . this tree has the property that each vertex of @xmath67 is connected to a leaf by a single edge . each leaf - edge of this tree corresponds to a marked point , and is assigned a @xmath18 or @xmath68 , the internal edges are each assigned a copy of the borel subgroup @xmath69 . each internal vertex of @xmath67 now has three parabolic subgroups assigned to its incident edges , so following @xcite , we think of this vertex as corresponding to the total coordinate ring of the moduli of quasi - parabolic principal bundles on @xmath64 with parabolic structure coming from the corresponding parabolic subgroups . four types of total coordinate rings appear , @xmath70 @xmath71 @xmath72 and @xmath73 we call these the @xmath3pieri algebras for reasons that will be made clear . the following theorem expresses the degeneration of @xmath27 in terms of these algebras , it follows from theorem @xmath61 from @xcite . [ degen ] the algebra @xmath27 has a flat degeneration to the following algebra . @xmath74^{\otimes a-2 } \otimes [ v_{0 , 3}(b , p^ * , b)]^{\otimes b- 2 } \otimes v_{0 , 3}(b , p^ * , p^*)]^{t}\\\ ] ] this is the algebra of invariants in a tensor product of @xmath3pieri algebras by a torus @xmath75 this torus is a product of @xmath76 copies of @xmath77 one for each internal edge of @xmath78 where @xmath79 is the torus of diagonal matrices , we describe the action of this torus below . equation [ specialpic ] is a special case of a more general theorem due to laszlo and sorger , @xcite , which expresses the picard group of the moduli @xmath14 of quasi - parabolic principal bundles on a curve @xmath10 with parabolic structure @xmath80 at @xmath13 in terms of the character groups @xmath81 of the associated parabolic subgroups . @xmath82 when each @xmath80 is the borel subgroup @xmath83 , we let @xmath84 denote the corresponding cox ring . this algebra contains the cox rings of all other moduli of principal bundles as a multigraded subalgebra , in particular @xmath85 contains each of the @xmath3pieri algebras as multigraded subalgebras . by laszlo and sorger s theorem , the cox rings @xmath70 @xmath71 @xmath72 @xmath86 are multigraded by triples of dominant @xmath0 weights . the algebra @xmath87 is given as an example below . @xmath88 here @xmath89 . the weights @xmath90 are allowed to vary over all dominant weights in the weyl chamber @xmath91 whereas @xmath92 is always taken from the ray through @xmath93 corresponding to the parabolic subgroup @xmath94 the analogous expression holds for @xmath87 , @xmath95 , @xmath73 this implies that the tensor product @xmath96^{\otimes a-2 } \otimes [ v_{0 , 3}(b , p^ * , b)]^{\otimes b- 2 } \otimes v_{0 , 3}(b , p^ * , p^*)\\\ ] ] is a multigraded sum of spaces @xmath97 @xmath98 @xmath99 + the torus @xmath100 action on these spaces is by the characters determined by the weight information @xmath101 . a graded component of the invariant algebra @xmath102 of the torus @xmath100 therefore has @xmath103 and @xmath104 this allows us to understand properties of the degeneration @xmath102 by studying the @xmath3pieri algebras . in order to understand the structure of these algebras , in particular their multigraded components , we exploit a connection between moduli of principal bundles on curves and mathematical physics the moduli of quasi - parabolic principal bundles on a smooth marked curve have a close connection with conformal field theory , in particular the non - abelian theta functions are identified with the partition functions from the wess - zumino - witten model of conformal field theory , and so - called conformal blocks . this theory associates a space of conformal blocks @xmath105 to each stable , marked curve @xmath106 , assignment of dominant weights @xmath107 and non - negative integer @xmath108 the theorem establishing this relationship in various cases is due to narasimhan , ramanathan , kumar ; beauville , laszlo , sorger ; faltings ; and pauly . for @xmath106 a smooth marked curve , @xmath109 @xmath110 conformal blocks are also the structure spaces of a monoidal operation called the fusion product on integrable highest - weight representations of the affine kac - moody algebra @xmath111 . as a consequence , we may bring in the associated combinatorial representation theory to analyze the graded pieces of @xmath112 in particular , we use a result called the @xmath3pieri rule , that each graded component of @xmath70 @xmath71 @xmath113 and @xmath86 is multiplicity free . for a description of the @xmath3pieri rule in the context of fusion coefficients see section @xmath114 of @xcite . this result implies that each @xmath3pieri algebra has a basis labelled by the weight data @xmath115 of their graded components @xmath116 and multiplication of basis members is simple addition on this weight data . formally then we say that the @xmath3pieri algebras are affine semigroup algebras for semigroups of weight data @xmath117 , @xmath118 @xmath119 @xmath120 . we must first determine the structure of these semigroups . [ kpieri][the k - pieri rule ( reformulated ) ] the space @xmath121 has dimension @xmath42 or @xmath122 this space has dimension @xmath123 if and only if there is a positive @xmath47 dominant weight @xmath124 such that the following hold . 1 . @xmath125 + 2 . @xmath126 + 3 . @xmath127 + 4 . @xmath128 + the entries of the dominant weights @xmath129 from proposition [ kpieri ] can be placed in an interlacing diagram , shown in figure [ pieri ] for @xmath130 notice that @xmath124 can be recovered from the data @xmath131 namely @xmath132 , @xmath133 @xmath134 + [ pieri ] for such a pattern @xmath135 we define its boundary weights as follows . @xmath136 @xmath137 by duality considerations , the space @xmath121 is non - zero with dimension @xmath123 if and only if the same is true for @xmath138 . for this reason , interlacing patterns also give a mechanism to label the ( multiplicity free ) graded components of the algebra @xmath95 . the space @xmath139 is labelled by @xmath140 weights @xmath141 and @xmath142 , which satisfy the following . 1 . @xmath143 + 2 . @xmath144 + 3 . @xmath145 + 4 . @xmath146 + we illustrate interlacing patterns @xmath147 for the spaces @xmath148 with the opposite orientation . @xmath149 + [ pieridual ] we apply the boundary maps @xmath150 to interlacing patterns @xmath147 as follows . @xmath151 @xmath152 each such interlacing pattern labels one of the multiplicity - free spaces in the multigraded decomposition of @xmath153 and @xmath87 and likewise @xmath95 and @xmath86 . the algebra @xmath102 is also graded by multiplicity - free components , and is therefore an affine semigroup algebra for an affine semigroup @xmath154 . the elements of @xmath154 are lists of elements @xmath155 from the semigroups above , which can be glued along their boundary data , @xmath156 @xmath157 @xmath158 . we will present this semigroup explicitely , by first analyzing each of the four algebras @xmath70 @xmath71 @xmath72 @xmath73 and then by controlling the `` gluing '' procedure . the following proposition , proved in section [ lv ] , says that the four algebras we consider as our building components are not very complicated . [ poly ] the algebras @xmath159 are polynomial rings on @xmath160 variables . the algebras @xmath161 are polynomial rings on @xmath162 variables . we will prove this proposition by carefully reproving the @xmath3pieri rule using elements of commutative algebra . this continues a theme first established in @xcite and continued in @xcite , that the combinatorics of the conformal blocks are related to toric degenerations of the moduli of quasi - parabolic principal bundles . the gluing operation described above should be a familiar operation for researchers who study affine semigroup algebras . the following proposition is a consequence of the description of @xmath102 as an algebra of torus invariants in a tensor product of the @xmath3pieri algebras . [ tfiber ] the affine semigroup @xmath154 is a toric fiber product of the affine semigroups associated to the @xmath3pieri algebras . toric fiber products of affine semigroups are defined in @xcite , and further explored in @xcite . informally we may think of the toric fiber product as a way to glue the @xmath3pieri semigroups corresponding to the above interlacing diagrams together to produce a composite semigroup @xmath154 , and indeed we describe the defining inequalities and corresponding diagram of this semigroup in section [ gt ] . in section [ gt ] we also describe a polytope @xmath163 whose graded affine semigroup algebra is induced the degeneration of the projective coordinate ring @xmath164 we make use of the fiber product structure on @xmath154 , and general theorems on toric fiber products from @xcite and @xcite , to prove an explicit presentation of @xmath112 the set @xmath165 is defined to be the set of all tuples @xmath166 $ ] of @xmath167 elements from @xmath168 such that the first and last entries are @xmath48 or @xmath42 , and the difference @xmath169 is in @xmath170 if @xmath171 and in @xmath172 if @xmath173 . on the set of tuples above , a swap is a quadratic polynomial of the following form , @xmath174[\vec{i_1}^ * , i , \vec{i_2}^ * ] - [ \vec{i}_1 , i , \vec{i_2}^*][\vec{i_1}^ * , i , \vec{i_2}]\\\ ] ] [ toricmain ] the algebra @xmath102 is presented by generators @xmath175 subject to all possible swap relations . this is a presentation of @xmath102 by generators and relations . the fiber product structure of @xmath154 also allows us to prove that the algebra @xmath102 is gorenstein , and that it possesses a quadratic square - free grbner basis given by the swap relations above , in section [ lv ] . these properties then lift to the algebra @xmath27 for generic @xmath37 by general properties satisfied by algebras in flat families , see the proof of theorem @xmath176 in @xcite . in order to prove these results , in particular proposition [ poly ] , we study an auxiliary semigroup @xmath177 , which comes from a classical algebra from invariant theory . one of our motivations in studying the algebra @xmath178 is that it bears a resemblance to the object of study in a classical theorem in invariant theory due to weyl . we let @xmath179 be the algebra of @xmath0 invariants in the coordinate ring of the affine space @xmath180^a \times [ \c^m]^b$ ] . @xmath181^a \times [ \c^m]^b]^{sl_m(\c)}\\\ ] ] we view the algebra @xmath182^a \times [ \c^m]^b]$ ] as a polynomial ring on @xmath183 variables , arranged in a matrix , with the columns labelled by elements of @xmath184 = [ a ] \coprod [ b]$ ] . @xmath185 we let @xmath186 be the determinant form on the variables determined by a subset @xmath187 $ ] in @xmath180^a$ ] of size @xmath49 , and @xmath188 be the dual determinant in @xmath189^b,$ ] for @xmath190.$ ] we let @xmath191 be the column - wise inner product of the variables on the indices @xmath192 $ ] with those in @xmath193.$ ] each of the elements @xmath194 is an @xmath0 invariant , and therefore a member of @xmath179 . weyl described a collection of quadratic relations on these elements , known as the plcker relations . the algebra @xmath179 is generated by the @xmath194 , and all relations among these generators are generated by the plcker relations . the algebra @xmath179 is multigraded by an action of @xmath195 copies of the maximal diagonal torus @xmath79 . the components of this multigrading are the @xmath0 invariant spaces in the tensor products , @xmath196 in @xcite a relationship is established between @xmath179 and @xmath27 . for any collection of @xmath197 points @xmath198 the algebra @xmath27 is a @xmath199multigraded subalgebra of the polynomial ring over weyl s invariant ring , @xmath200.$ ] @xmath201 theorem @xmath176 in @xcite implies that the degeneration of @xmath27 corresponding to @xmath67 we use here also applies to the algebra @xmath179 . this connection allows us to use the algebra @xmath179 to study @xmath202 we will show how a similar analysis of @xmath179 using the classical pieri rule yields the following presentation of this degeneration , @xmath203 let @xmath204 by the subset of tuples which are unbroken strings of non - zero entries . [ tenstoric ] the algebra @xmath205 is presented by @xmath206 with respect to the swap relations on these generators . this gives a presentation of @xmath205 , in section [ pr ] we will describe an explicit affine semigroup @xmath177 such that @xmath207 = r_{\tree_0}(a , b).$ ] the elements @xmath186 , @xmath188 , and @xmath191 from weyl s presentation correspond to minimal generators in the degeneration @xmath208 as follows . for the set @xmath187,$ ] we let @xmath209 be the tuple with @xmath210 exactly for @xmath211 and we define @xmath212 for @xmath190 $ ] similarly . we let @xmath213 be the tuple with @xmath210 , @xmath214,and all other differences equal to @xmath42 . these elements constitute a proper subset of @xmath206 , so the presentation emerging from the degeneration @xmath205 is perhaps not as efficient as weyl s presentation , however it is better suited to aid in our description of @xmath102 . the paper is organized as follows . in section [ tfp ] , we review the toric fiber product construction and some of its properties . in section [ pr ] , we review the classical pieri rule from the representation theory of @xmath60 in section [ lv ] , we study a valuation on the algebra of tensor product invariants which will help us to understand the semigroup algebra @xmath154 , we prove the @xmath3pieri rule from the classical pieri rule , we prove theorem [ main ] . in section [ gt ] , we construct @xmath154 as a set of weightings on an interlacing pattern . in this section we review the toric fiber product operation on affine semigroup algebras . this is the `` gluing '' operation we will need to build the affine semigroup algebras @xmath205 , @xmath102 from their component semigroup algebras . to this end , we will pay special attention to toric fiber products of simplicial cones over a simplicial cone base . we will review results from @xcite and @xcite which control the algebraic behavior of these semigroups . for @xmath215 , @xmath216 , @xmath217 polyhedral cones , and @xmath218 linear maps with @xmath219 the toric fiber product is the set , @xmath220 the fiber product @xmath221 is also a polyhedral cone . if @xmath222 @xmath223 and @xmath224 are lattices , with @xmath225 , then the set @xmath226 is called the fiber product semigroup of the affine semigroups @xmath227 and @xmath228 from now on we abuse notation and refer to the semigroup by its defining cone . if the generators of the affine semigroups of these bodies behave well with respect to the maps @xmath229 then the affine semigroup of the associated toric fiber product also behaves well . the following can be found in @xcite , and a variant appears in @xcite . [ semigen ] let @xmath230 @xmath231 , and @xmath232 denote the generating sets of the affine semigroups associated to polyhedral cones @xmath233 with respect to lattices @xmath234 suppose that @xmath235 , and that @xmath236 is a simplicial cone , then the set @xmath237 generates the product semigroup @xmath238 for any semigroup element @xmath239 , we can factor @xmath240 , @xmath241 . we then get factorizations , @xmath242 the affine semigroup @xmath236 has unique factorization , because it is a simplicial cone . it follows then that @xmath243 and the sets @xmath244 , @xmath245 are equal . the elements of the sets @xmath246 and @xmath247 can be matched in some way @xmath248 , so that the resulting pairs have the same image under @xmath249 . we therefore obtain a factorization , @xmath250 several of the elements @xmath246 may have the same image under @xmath251 , this could lead to distinct assignments @xmath248 which produce different factorizations of the element @xmath252 these factorizations are related by swap relations . let @xmath253 @xmath254 with @xmath255 , then the following is a swap relation in @xmath238 @xmath256 [ semirel ] with the assumptions of proposition [ semigen ] , the relations of @xmath257 are generated by those which generate relations for the @xmath258 and the swap relations . we consider a relation in @xmath221 , @xmath259 once again , the sets images of these two sets of elements in @xmath236 must agree , so @xmath260 . the word @xmath261 can be transformed to @xmath262 by a series of generating relations in @xmath263 . we claim that each such relation can be lifted to a relation on generators in @xmath238 if @xmath264 is such a relation , then the image sets under @xmath251 must agree , so each relation can be performed without changing the set @xmath265 . this implies that at each stage , these sets can be assigned to elements in the set @xmath266 to form elements from the fiber product . it follows that @xmath267 can be transformed to @xmath268 by relations lifted this way from @xmath263 and @xmath269 where the @xmath270 and @xmath271 are the @xmath272 and @xmath273 matched in a different way . now this word can be rearranged into @xmath274 using swap relations . in @xcite and @xcite it is shown that if the ideals defining @xmath275 , \c[p_2]$ ] under presentation by @xmath276 have quadratic , square - free grbner bases , then so does the ideal defining @xmath277 $ ] . in particular , if @xmath233 are simplicial cones with @xmath235 , the ideal defining @xmath277 $ ] has a quadratic , square - free grbner basis made of swap relations . from this we can deduce the following proposition . [ kos ] let @xmath278 be a fiber product of simplicial cones over simplicial cones , by maps which take generators to generators . then the swap relations define a quadratic , square - free grbner basis on the defining ideal of @xmath279 $ ] under the presentation by the fiber product generating set . affine semigroup algebras are appealing because their inherent combinatorial nature allows many of their commutative algebra properties to be expressed in therms of polyhedral geometry . the following is corollary @xmath280 of @xcite . let @xmath10 be an affine semigroup algebra , with @xmath281 the set of interior lattice points . the algebra @xmath282 $ ] is gorenstein if and only if @xmath283 for some @xmath284 in @xcite , we gave the following condition for a fiber product semigroup algebra of gorenstein semigroups to be gorenstein . the conditions of this proposition are satisfied for the semigroups we consider in this paper , and indeed are satisfied for any fiber product of simplices over simplices , where the maps in question are surjective on generating sets . [ gor ] let @xmath233 be semigroups with gorenstein semigroup algebras , and let @xmath285 be the corresponding generators of the interior sets . then if @xmath286 , the semigroup algebra @xmath221 is gorenstein . in this section we decribe the algebra @xmath179 in terms of the representation theory of @xmath287 and an associated flat degeneration to an affine semigroup algebra @xmath207 $ ] . in order to define the affine semigroup @xmath177 we will recall the pieri rule for decomposing tensor products of @xmath0 representations , and describe how this rule informs the combinatorial commutative algebra of @xmath288 first we introduce the algebra @xmath289 of invariant vectors in @xmath290fold tensor products of irreducible @xmath0 representations . we let @xmath291 denote the cox ring of the full flag variety of @xmath0 , as a vector space , this algebra is a multiplicity - free direct sum of all irreducible representations of @xmath0 . @xmath292 the multiplication operation in this algebra is given by projecting on the highest weight component of a tensor product . @xmath293 this algebra is multigraded by the dominant weights @xmath294 and can also be constructed as the algebra of invariants in @xmath295 $ ] with respect to the unipotent group of upper triangular matrices . we define @xmath289 to be the algebra of @xmath0 invariants in an @xmath290fold tensor product of copies of @xmath291 . as a vector space , this is a direct sum of all invariant spaces in @xmath290fold tensor products of @xmath0 representations . @xmath296^{sl_m(\c)}\\\ ] ] the coordinate rings of @xmath2 and @xmath1 are graded subalgebras of @xmath291 , they can be identified with the sums of those representations of the form @xmath297 and @xmath298 , respectively . it follows that the algebra @xmath179 is a multigraded subalgebra of @xmath299 . in @xcite and @xcite we describe a flat degeneration of @xmath289 for each trivalent tree @xmath38 with @xmath39 leaves . in @xcite , it is shown that the lift of these degenerations to @xmath300 $ ] is compatible with the corresponding degeneration on @xmath27 under the inclusion map in equation [ inc ] . in particular , for the tree @xmath67 , @xmath289 degenerates to the algebra of invariants @xmath301^{t^{n-3}}$ ] , where @xmath302 is a product of @xmath303 copies of the maximal torus @xmath304 acting as in theorem [ degen ] . in order to pass this description to @xmath179 , we define four subalgebras of @xmath305 . the algebras @xmath306 and @xmath307 are the multigraded subalgebras of @xmath305 whose componants have middle dominant weight equal to a multiple of @xmath308 and @xmath309 , respectively . the algebras @xmath310 and @xmath311 are defined accordingly . we call the algebras @xmath312 @xmath313 @xmath314 and @xmath311 the pieri algebras . theorem @xmath176 from @xcite implies that @xmath179 has a flat degeneration to the following invariant algebra . @xmath315^{\otimes a-2 } \otimes [ r_3(b , p^ * , b)]^{\otimes b-2 } \otimes r_3(b , p^ * , p^*)]^{t^{a+b-3}}\\\ ] ] here , once again , @xmath316 is a product of @xmath317 copies of the maximal torus of @xmath0 , and taking invariants by @xmath100 ensures that all graded components of @xmath205 are of the following form . @xmath318 @xmath319 @xmath320 + the following is the classical pieri rule , it is a basic component of @xmath0 representation theory . we refer the reader to any basic text covering this subject , for example the book of fulton and harris , @xcite . [ p2][the pieri rule ] the invariant space @xmath321 is multiplicity free , and it has dimension @xmath123 precisely when there is a @xmath47 weight @xmath124 such that the following hold . 1 . @xmath125 + 2 . @xmath126 + 3 . @xmath128 + weights which satisfy these conditions can be arranged in interlacing patterns , as depicted in figure [ pieri2 ] . @xmath322 + interlacing conditions governing the spaces @xmath323 can be derived by duality . for this space to have dimension @xmath123 , there must be a @xmath47 weight @xmath142 such that the following hold , see figure [ pieri2dual ] . 1 . @xmath324 + 2 . @xmath325 + 3 . @xmath146 + @xmath326 + we define boundary maps @xmath150 for these patterns as in the @xmath3pieri case . the algebra @xmath310 is composed of components of the form @xmath327 , following the recipe above , the interlacing inequalities give us patterns as in figure [ pieri3 ] . dual patterns are depicted in figure [ pieri4 ] for spaces of the form @xmath328 . @xmath329 + @xmath330 + notice that both of these diagrams are determined by @xmath114 parameters . since each multigraded component of the pieri algebras is dimension @xmath42 or @xmath123 , these algebras are all affine semigroup algebras , we refer to their underlying semigroups by @xmath331 @xmath332 @xmath333 and @xmath334 . the following proposition shows that each of these semigroups has a simple structure . [ cpresent ] the algebras @xmath306 and @xmath307 are polynomial algebras on @xmath335 variables . the algebras @xmath310 and @xmath311 are polynomial algebas on @xmath114 variables . duality is a linear operation on dominant weights , so it follows that the statement for the algebras @xmath307 and @xmath311 is a consequence of the statement for @xmath306 and @xmath310 respectively , so we present proofs for these cases . from figure [ pieri3 ] we directly compute that the algebra @xmath310 is generated by the patterns in figure [ pieripattern1 ] . @xmath336 + any element of @xmath310 is a unique product of the elements reprsented by these patterns . we label these elements by recording their boundary fundamental @xmath47 weights , from top down they are @xmath337,$ ] @xmath338 $ ] , and @xmath339 $ ] . the identity @xmath340 corresponds to the trivial invariant in @xmath341 , we label this element with @xmath342.$ ] in general , we let @xmath343 $ ] and @xmath344 $ ] denote the patterns in figure [ pieripattern2 ] . @xmath345 + an interlacing pattern @xmath135 is decomposed uniquely into a sum of these patterns by finding the smallest non - zero entry , and pulling the pattern above with the first @xmath123 occuring at this entry off until this entry is @xmath42 . @xmath346 + @xmath347 + ( b_{m-1 } - a_{m-1})[m-1 , m-1 ] + \ldots + ( a_1 - \sum_{j > 1 } a_j + b_{j-1 } ) [ 1 , 0]\\\ ] ] the indices @xmath348 in the generators @xmath349 $ ] of these semigroups range between @xmath123 and @xmath49 . as @xmath49 corresponds to the trivial dominant weight @xmath350 , we consider these elements as members of @xmath351 in particular @xmath352 = [ m , m].$ ] the multigraded components of @xmath205 all have dimension @xmath123 or @xmath42 , and have dimension @xmath123 exactly when each part of the tensor product satisfies the conditions of proposition [ p2 ] . we use this fact to describe an affine semigroup @xmath177 such that @xmath353.$ ] we define @xmath177 to be the affine semigroup obtained by taking the following fiber product over the boundary maps @xmath150 . the image of these boundary maps is the affine semigroup for the simplicial cone @xmath354 with @xmath48 generators . @xmath355 @xmath356 @xmath357 the boundary maps @xmath150 were defined to capture the operation of taking invariants by the torus @xmath358 , so the semigroup algebra of @xmath177 can be identified with @xmath205 by definition . proposition [ semigen ] then implies that elements composed of generators of pieri semigroups suffice to generate @xmath177 , and therefore @xmath203 the semigroups @xmath359 , @xmath360 , @xmath332 and @xmath334 are generated by elements labelled by pairs @xmath349 $ ] , where @xmath348 are elements of @xmath168 . it is easily checked from the definition of the boundary maps @xmath150 that two of these generators @xmath349,[k , l]$ ] can be glued when @xmath361 . this implies that a generating set of @xmath177 is given by @xmath362 tuples of elements from @xmath351 @xmath363\\\ ] ] where @xmath364 and @xmath365 can be @xmath49 or @xmath48 , the first @xmath366 differences @xmath367 must be @xmath42 or @xmath123 and the last @xmath368 differences must be @xmath42 or @xmath369 all of these conditions holding modulo @xmath370 by proposition [ semirel ] the relations on these generators are generated by the swap relations . since the element @xmath371 $ ] represents @xmath372 , the swap relations tell us that an element of the form @xmath373 $ ] may be factored , @xmath374[0 , \ldots , 0 , \ldots , 0 ] = [ i_1 , \ldots , i_{k+2 } , 0 , \ldots , 0][0 , \ldots , 0 , i_{k+2 } , \ldots , i_{a + b -1}]\\\ ] ] from this it follows that @xmath177 is generated by unbroken strings of nonzero entries from @xmath375 in this section we study the four @xmath3pieri algebras , @xmath376 @xmath113 @xmath377 @xmath378 we will use the results of the previous section to prove that each of these algebras is a polynomial ring , and then use this fact to find a presentation of the algebra @xmath112 conformal blocks @xmath379 in the genus @xmath42 case can be recovered as a subspace of the space of @xmath380invariant vectors in the tensor product @xmath381 . the precise subspace depends on the data @xmath382 the moduli of @xmath383marked projective lines is a single point , so in this case there is a unique space of conformal blocks , @xmath384 , which can be explicitely defined as a subspace of @xmath385^{sl_m(\c)}$ ] using elements of the classical representation theory of @xmath60 we consider the copy of @xmath41 inside @xmath0 which corresponds to the longest root @xmath386 each representation @xmath387 can be decomposed into isotypical components of this subgroup @xmath388 in @xcite , ueno defines the following subspace @xmath389 . @xmath390 the following proposition can also be found in @xcite . [ ueno ] the space of conformal blocks @xmath384 can be identified with the space @xmath391^{sl_m(\c)}.$ ] proposition [ ueno ] can be used to define a function @xmath392 as follows . on pure graded components of @xmath305 we define @xmath393 on @xmath394 using the subspace @xmath395 , @xmath396 this is extended to mixed grade components using the @xmath397 function , @xmath398 by convention we set @xmath399 this function was studied in @xcite , where it was shown to be a valuation on @xmath305 , see also page @xmath400 in @xcite . this means that @xmath393 has the following properties . 1 . @xmath401 + 2 . @xmath402 + 3 . @xmath403 + in terms of this function , the graded components of @xmath85 are the following subspaces of the graded components of @xmath404 @xmath405^{sl_m(\c)}\\\ ] ] there are corresponding inclusions of the @xmath3pieri algebras into polynomial rings over the pieri algebras . @xmath406\\\ ] ] @xmath407\\\ ] ] @xmath408\\\ ] ] @xmath409\\\ ] ] now our task is to establish explicitely the @xmath393 value for a non - trivial vector in each graded component of the pieri algebras , this will allow us to compute a presentation for the @xmath3pieri algebras . in order to do this , we find @xmath410 for each generator @xmath100 of @xmath306 , @xmath307 , @xmath314 and @xmath411 and use this calculation to find the @xmath393 value for each monomial in the generators . the generators of the pieri algebras are precisely the unique invariants in tensor products of the form @xmath412 and @xmath413 where @xmath414 and @xmath415 where @xmath416 note that the sum of these indices must be equal to @xmath160 or @xmath370 both invariant types can be viewed as a representation of the determinant , and have the following form as alternating tensors . @xmath417 @xmath418 @xmath419 here @xmath420 is a wedge product of basis vectors over the indicated index set , and @xmath421 is a sign function . the following is well known in the type @xmath422 conformal blocks literature . each generating invariant of the pieri algebras has @xmath393 value equal to @xmath122 to evaluate @xmath393 on these elements , we reduce to the case where the sum of the indices is @xmath423 as the @xmath160 case is related to this case by duality . in this case , each of the terms in the expansion above is of the form @xmath424 with @xmath425.$ ] when this term is considered with respect to the @xmath426 subgroup isomorphic to @xmath427 its properties are determined by whether or not the indices @xmath428 show up in the sets @xmath429 there are two possibilities . if @xmath123 and @xmath39 are in separate index sets , the term corresponds to an invariant in the @xmath41 representation @xmath430 and therefore has @xmath393 value @xmath431 . if both @xmath123 and @xmath39 appear in the same index set , the term is the trivial invariant in @xmath432 , and has @xmath393 value @xmath42 . the value on the sums of these terms is therefore @xmath122 we focus briefly on a particular @xmath3pieri algebra , @xmath87 . we associate each generator @xmath343 , [ i+1 , i]$ ] to the elements @xmath343 t , [ i+1 , i]t \in v_{0 , 3}(b , p , b ) \subset r_3(b , p , b ) \otimes \c[t]$ ] . now consider a non - trivial element @xmath433 the invariant represented by @xmath135 has a monomial decomposition into the generators above . @xmath434^{n_i}[j , j]^{m_j}\\\ ] ] multiplicative properties of valuations then give us @xmath435 . this implies that in the @xmath3pieri algebra we have @xmath436t)^{n_i } ( [ j , j]t)^{m_j}t^{k - \sum n_i - \sum m_j}.\\\ ] ] the same argument applies for the other @xmath3pieri algebras . as a consequence we obtain the following theorem . the algebras @xmath87 and @xmath95 are polynomial algebras on @xmath160 generators . the algebras @xmath153 and @xmath86 are polynomial algebras on @xmath162 generators . the generators of these algebras are the generators of the corresponding pieri algebras , along with the identity @xmath342 $ ] , multiplied by the auxiliary variable @xmath437 . this also gives the following characterization of the non - zero spaces @xmath438 the space of conformal blocks @xmath439 is multiplicity free , and dimension @xmath123 if and only if the conditions in proposition [ kpieri ] hold . this follows from equation [ decomp ] and the fact that the @xmath393 of the patterns @xmath343 , [ i+1 , i]$ ] are given by the first entry on the top row . @xmath346 + @xmath347 + ( b_{m-1 } - a_{m-1})[m-1 , m-1 ] + \ldots + ( a_1 - \sum_{j > 1 } a_j + b_{j-1 } ) [ 1 , 0]\\\ ] ] we are now in a position to construct the affine semigroup @xmath440 as polynomial algebras , the @xmath3pieri algebras @xmath376 @xmath113 @xmath377 and @xmath441 are affine semigroup algebras on simplicial cones , with @xmath442 generators respectively . we construct @xmath154 as a toric fiber product of the corresponding semigroups following a procedure similar to the construction of @xmath443 the only extra detail is that , in addition to the boundary maps @xmath150 on the interlacing patterns for these algebras , we must also include the level data . this implies that two interlacing patterns can be glued only if they share the same boundary weight data and level . the semigroup @xmath154 is obtained as fiber product over the affine semigroup of the simplicial cone @xmath444 with @xmath49 generators . @xmath445 @xmath446 @xmath447 + by proposition [ semigen ] , a generating set of @xmath154 is obtained by taking all tuples of level @xmath123 generating elements @xmath448 , \ldots , [ i_{a+b-2 } , j_{a + b -2}]$ ] , where @xmath449 . note that , as all generators are tuples of level @xmath123 elements , and any product of level @xmath123 elements is a level @xmath450 element , this is already a minimal generating set of @xmath440 by the descriptions of the pieri algebra generators above , the generators of @xmath154 are exactly those @xmath167 tuples which satisfy the following properties , all elements are members of @xmath375 1 . the difference @xmath451 is @xmath452 for @xmath171 . the difference @xmath451 is @xmath453 for @xmath454 . the first and last entries are members of @xmath455 + by proposition [ semirel ] , the relations for @xmath154 are generated by the swap relations among these generators . this gives the presentation of @xmath456 and completes the proof of theorem [ toricmain ] . note that propositions [ gor ] and [ kos ] also imply that both @xmath102 and @xmath205 are gorenstein algebras with quadratic , square - free grbner bases . this in turn implies the following . the algebras @xmath179 and @xmath27 are gorenstein , koszul algebras when @xmath37 is generic . furthermore , since @xmath27 is graded by the level data , and the only elements of level @xmath42 are multiples of the identity @xmath457 , the level @xmath123 elements constitute a minimal generating set of this algebra . in this section we describe elements of the fiber product semigroups @xmath154 and @xmath177 as labellings of interlacing diagrams . we have defined the interlacing patterns for the @xmath3pieri and pieri semigroups and their boundary maps @xmath150 specifically with the gluing operation in mind . we slightly modify these boundary maps , after taking @xmath458 , or @xmath459 , we always then pass from a positive @xmath47 weight to the underlying @xmath0 weight . we consider a tensor product , @xmath460 . by the pieri rule , this space is non - zero if and only if there are two interlacing patterns @xmath461 such that @xmath462 @xmath463 @xmath464 and @xmath465 . these conditions can be represented with a @xmath466step interlacing diagram with entries as depicted in figure [ pieri5 ] . notice that the top two rows of this diagram have been modified from what they would have been had we considered the space @xmath468 by itself . in particular , the the following diagram has been added to the top two rows . this does not change the boundary values of the pattern as it represents the trivial tensor product invariant in @xmath470 . this operation is performed to make the gluing procedure easier , namely one pattern is modified until its boundary weights match , which is always possible when @xmath471 . then it is simply stacked on top of the lower pattern . patterns as in figure [ pieri5 ] label the graded components of the algebra @xmath472^t.$ ] to represent more complicated tensor products , we simply stack the appropriate patterns , taking care to modify pairs of rows by the null pattern to correctly identify the weights when necessary . we define @xmath473 to be the `` wedge '' interlacing pattern in figure [ wedge ] , with rows of length @xmath49 , @xmath17 steps before the switch in direction , and @xmath19 steps after the switch in direction . the next two propositions then follow from our combinatorial descriptions of the algebras @xmath205 and @xmath102 . the level condition in proposition [ kpieri ] has been altered to account for the possible addition of the null diagram to a pair of rows . 1 . the boundary value of the top row is @xmath476 . the boundary value of the bottom row is @xmath477 . the difference between the sums of the @xmath478 and @xmath479st rows is @xmath480 if @xmath481 and @xmath482 is @xmath483 + 1 . the boundary value of the top row is @xmath476 . the boundary value of the bottom row is @xmath477 . the difference between the sums of the @xmath478 and @xmath479st rows is @xmath480 if @xmath481 and @xmath482 is @xmath483 + 4 . for rows @xmath485 , the difference between the first entry of row @xmath478 and the last entry of row @xmath486 is @xmath487 . f rows @xmath488 , the difference between the last entry of row @xmath478 and the first entry of row @xmath479 is @xmath489 + the labellings in proposition [ levelgt ] are the lattice points in a polytope @xmath163 . the graded affine semigroup algebra determined by this polytope , @xmath490 $ ] is the degeneration of the projective coordinate @xmath491 induced from the degeneration of @xmath27 to @xmath112 this algebra is considerably more complicated than @xmath456 it would be interesting to find a generating set of lattice points for this semigroup , or a classification of which @xmath492 yield a gorenstein algebra .

we study a toric degeneration of the cox ring of the moduli of principal @xmath0 bundles on the projective line , with quasi parabolic data given by the the stabilizer of the highest weight vector in @xmath1 and its dual @xmath2 . the affine semigroup algebra resulting from this degeneration is described using the @xmath3pieri rule from kac - moody representation theory . along the way we give a proof of the @xmath3pieri rule which utilizes the classical pieri rule and elements of commutative algebra , and we describe a relationship between the cox ring and a classical invariant ring studied by weyl . [ multiblock footnote omitted ] keywords : conformal blocks , pieri rule , toric degeneration , invariant theory

while analytic solutions for isolated black holes ( bhs ) have a long history , the dynamics of bh binaries has been solved only recently and through computationally - expensive numerical - relativity ( nr ) calculations [ see @xcite for a review ] . despite the mathematical complexity of the problem , many results of the nr simulations can be reproduced accurately using semi - analytical prescriptions @xcite based on post - newtonian ( pn ) and bh perturbation theory . it is therefore not entirely surprising that the dimensionless spin of the remnant from a bh - binary merger , @xmath0 , can be described , with increasing accuracy , via simple prescriptions based on point particles @xcite , on fits to the nr data @xcite , or on a combination of the two approaches @xcite [ see @xcite for a review ] . these formulas are useful because they provide information over the entire 7-dimensional parameter space for bh binaries in quasi - circular orbits , namely : the mass ratio @xmath1 and the six components of the initial dimensionless spin vectors @xmath2 . such parameter space could in principle be investigated entirely via nr calculations ; in practice , however , the simulations are still very expensive and restricted to @xmath3@xmath4 . also , these formulas have many applications : in astrophysics , where they could provide information on massive star binaries @xcite ; in cosmology , where supermassive bhs ( smbhs ) are believed to assemble through accretion and mergers @xcite ; in gravitational - wave astronomy , where _ a priori _ knowledge of the final spin can help the detection @xcite . while the different expressions for the spin norm , @xmath5 , are in good agreement among themselves and with the numerical data , the predictions for the final - spin direction , @xmath6 , do not agree well with one another . moreover , all expressions are built from and model the typical `` nr binaries '' and hence the dynamics of the last few orbits before the merger , and do not account systematically for the precession of the orbital angular momentum @xmath7 , thus becoming imprecise when the binary is widely separated @xcite . of course , it is possible to use the pn equations and evolve a widely - separated binary to small separations , read - off the relevant information and apply the presently - available formulas [ this was suggested by @xcite , who correctly remark that their expression is valid only at small separations ] . while not a problem in principle , this procedure can be impractical in applications , such as cosmological merger - trees or n - body simulations , that provide the spins of the two bhs at separations of hundreds or thousands of gravitational radii . we follow here a different approach , and using assumptions slightly different from those made in @xcite , we present a new expression for @xmath8 which is applicable to binaries with arbitrary separations and which also provides better results for the final - spin direction at small separations . we recall that when the bhs have spins that are aligned with @xmath7 , the nr results are accurately described by @xcite @xmath9 where @xmath10 is the symmetric mass ratio and @xmath11 . the five coefficients @xmath12 , @xmath13 , @xmath14 , @xmath15 and @xmath16 in can be determined straightforwardly by fitting the results of the nr calculations . however , an additional condition can be employed by using the results obtained by @xcite for equal - mass non - spinning bhs and thus enforce that for @xmath17 and to the claimed precision @xmath18 this leaves only _ four _ unconstrained coefficients , so that by using the nr results for the 72 _ aligned _ binaries published so far @xcite we obtain @xmath19 with an agreement @xmath20 with the data . ] ; using the constraint ( 2 ) we then also obtain @xmath21 . because of the larger data set used , the values are slightly different from those in @xcite . because provides information over only 3 of the 7 dimensions of the parameter space , we will next show how to cover the remaining 4 dimensions and thus derive an expression for @xmath8 for _ generic _ bh binaries in quasi - circular orbits . following the spirit of @xcite , we make the following assumptions : _ ( i ) the mass @xmath22 radiated to gravitational waves can be neglected _ _ i.e. , _ @xmath23 . the radiated mass could be accounted for by using the nr data for @xmath24 @xcite or extrapolating the test - particle behavior @xcite . the reason why assumption _ ( i ) _ is reasonable is that @xmath22 is largest for aligned binaries , but these are also the ones employed to fit the free coefficients . therefore , @xmath22 is approximately accounted for by the values of the coefficients . _ ( ii ) the norms @xmath25 , @xmath26 , @xmath27 do not depend on the binary s separation @xmath28 _ , with @xmath29 being defined as @xmath30= \boldsymbol{l}(r)-\boldsymbol{j}_{\rm rad}(r)\,,\ ] ] where @xmath31 , @xmath32 and @xmath33 are the spins and the orbital angular momentum at separation @xmath28 and @xmath34 is the angular momentum radiated from @xmath28 to the merger . clearly , @xmath35 , @xmath36 and @xmath29 can still depend on @xmath28 through their directions . while the constancy of @xmath25 and @xmath26 is a very good assumption for bhs , which do not have an internal structure , the constancy of @xmath27 is more heuristic and based on the idea that the merger takes place at an `` effective '' innermost stable circular orbit ( isco ) , so that @xmath27 can be interpreted as the residual orbital angular momentum contributing to @xmath37 . _ ( iii ) the final spin @xmath37 is parallel to the initial total angular momentum @xmath38 . _ this amounts to assuming that @xmath39 . it replaces the assumption , made in @xcite , that @xmath40 , which is only valid for a smaller set of configurations . we note that this assumption is motivated by pn theory : within the adiabatic approximation , the secular angular - momentum losses via gravitational radiation are along @xmath41 @xcite . this is because as @xmath7 rotates around @xmath41 , the emission orthogonal to @xmath41 averages out . _ ( iv ) the angle between @xmath7 and @xmath42 and the angle between @xmath35 and @xmath35 are constant during the inspiral , although @xmath7 and @xmath43 precess around @xmath41 . _ at 2.5 pn order , @xmath44 and @xmath45 are approximately valid for any mass ratio if only one of the bhs is spinning , and for @xmath46 if one neglects spin - spin couplings . in both cases , in fact , @xmath43 and @xmath7 essentially precess around the direction @xmath47 , which remains nearly constant @xcite , and the angle between the two spins remains constant as well . the only case in which @xmath44 and @xmath45 are not even approximately valid is for binaries which , at some point in the evolution , have @xmath48 . these orbits undergo the so - called `` transitional precession '' @xcite , as a result of which @xmath47 changes significantly . because transitional precession happens only if @xmath7 and @xmath43 are initially _ almost _ anti - aligned with @xmath49 , it affects only a very small region of the parameter space , which is , moreover , poorly populated if the smbhs are in a gas - rich environment @xcite . because assumption _ ( iii ) _ plays a major role in our analysis , in fig . [ fig : test_assumption3 ] we provide evidence of its ( approximate ) validity by using all the _ generic _ bh - binary simulations ( _ i.e. , _ with spins _ not _ parallel to @xmath7 ) published so far @xcite , except two binaries in @xcite , which , when reproduced by us , seem affected by imprecisions ( m. jasiulek 2009 , private communication ) . in particular , we plot the angle between @xmath37 and @xmath50 as a function of the spin - spin coupling `` magnitude '' @xmath51 for the binaries with @xmath52 ( lower panel ) , and of @xmath53 for the binaries with @xmath54 ( upper panel ) . clearly , assumption _ ( iii ) _ is valid to within @xmath55 degrees , with maximum errors of @xmath56 degrees . these errors are compatible with the accuracy with which the nr simulations can compute the final - spin direction for strongly precessing binaries ( _ cf . _ the error s noisy dependence on @xmath51 ) . _ ( v ) when the initial spin vectors are equal and opposite and the masses are equal , the spin of the final bh is the same as for nonspinning binaries_. besides being physically reasonable reflecting the expectation that if the spins are equal and opposite , their contributions cancel out this assumption is confirmed by nr simulations [ _ c.f . _ discussion in @xcite ] and by the leading - order pn spin - spin and spin - orbit couplings . with these assumptions , we derive an expression for the final spin . let us write , using _ ( i ) _ , as @xmath57 where @xmath58 and @xmath59 . using _ ( ii ) _ , the final - spin norm is @xmath60^{1/2},\end{aligned}\ ] ] where @xmath61 and @xmath62 are @xmath63 note that because of @xmath45 @xmath64 does not depend on the separation and is simply the angle between the spins at the _ initial _ separation @xmath65 . the angles @xmath66 and @xmath62 are instead functions of the binary s separation , but this dependence cancels out in the linear combination in which they appear in , which is indeed , within the assumptions made , independent of the separation and which can therefore be evaluated at @xmath67 . to see this , let us consider expression at the effective isco . there , @xmath68 by definition and therefore @xmath69 . as a result , @xmath70 [ @xmath71 are simply the angles between @xmath35 [ @xmath36 ] and @xmath7 at the isco . using now assumption @xmath45 , we can write part of as @xmath73 where @xmath74 and @xmath75 are the angles between the spins and @xmath7 at _ any separation _ @xmath28 and thus also at @xmath67 @xmath76 this proves our previous statement : the dependence on @xmath28 that @xmath66 and @xmath62 have in expression is canceled by the linear combination in which they appear . stated differently , the final - spin norm is simply given by expression where @xmath77 and @xmath78 . thus , one does not need to worry about the angles between @xmath79 and @xmath80 but simply about the angles between @xmath79 and @xmath81 at @xmath67 , which are easy to compute . finally , we need to compute @xmath82 and for this we proceed like in @xcite and match expression at @xmath83 with for parallel and aligned spins [ @xmath84 , for parallel and antialigned spins [ @xmath85 , @xmath86 , and for antiparallel spins which are aligned or antialigned [ @xmath87 , @xmath88 or @xmath89 , @xmath90 . as noted in @xcite , this matching is not unique , but the degeneracy can be broken by exploiting assumption _ ( v ) _ ( _ i.e. , _ by imposing that @xmath91 does not depend on @xmath92 when @xmath93 and @xmath94 ) and by requiring for simplicity that @xmath91 depends linearly on @xmath95 , @xmath96 and @xmath97 . using these constraints and we obtain again an expression valid for _ any separation _ and hence for @xmath67 @xmath98 when comparing , and with ( 8) and ( 11 ) of @xcite , it is straightforward to realize that they are mathematically the same , although derived under a different ( and improved ) set of assumptions . this is simply because the new assumptions _ ( ii ) _ and _ ( iv ) _ are compatible , via equation , with the old ones . however , the new assumptions make a substantial difference in the prediction of the final - spin _ direction_. since _ ( iii ) _ states that @xmath99 , the angle @xmath100 between the final spin and the initial orbital angular momentum @xmath101 is given by @xmath102 this expression replaces and improves ( 10 ) of @xcite and , as we will show , is verified both for initial separations of a few gravitational radii , such as those considered in nr , and for larger separations ( _ e.g. , _ @xmath103 ) , which are relevant for cosmological applications . 1.0 cm 1.0 cm we now test our expressions , and for @xmath5 and our expression for @xmath100 against the nr simulations published so far for _ generic _ binaries . note that to test the expression for @xmath100 we use the same simulations as in fig . [ fig : test_assumption3 ] [ _ i.e. , _ @xcite ] , while to test the expression for @xmath5 we also use the data of @xcite ( which only reports the final - spin norm ) . also , we compare our predictions ( aei ) with those of similar formulas suggested by @xcite ( bkl ) , @xcite ( @xmath104 ) and @xcite ( fau ) . the comparison consists of two steps . first , we use as input the initial data of the nr simulations , in which the binaries have _ small separations _ ( _ i.e. , _ @xmath105 ) . second , we use binaries at _ large separations _ ( _ i.e. , _ @xmath106 ) , for which the dynamics starts being dominated by gravitational - wave emission and which are therefore of direct relevance for cosmological investigations . more precisely , we evolve the nr initial configurations back in time up to a separation of @xmath107 using the 2.5 pn equations in the quasi - circular limit @xcite , calculating the predictions of the different formulas at each step and considering the maximum error for each formula . ( we stress , however , that the figures we present do not change significantly if we integrate only up to a separation of @xmath108 . ) the left panel of fig . [ fig : afin ] shows the predictions of the various formulas for @xmath109 , when applied to the small - separation configurations corresponding to the initial data of the nr simulations . in particular , it reports the error in the final - spin norm @xmath110 where `` * '' stands for `` aei '' ( which , as already stressed , gives the same predictions for @xmath109 as `` @xmath104 '' ) , `` fau '' or `` bkl '' as a function of @xmath53 . the right panel shows instead the _ maximum _ error when the configurations are evolved back in time up to @xmath111 . [ fig : afin ] clearly shows that although the aei expression is slightly better , one _ can _ apply the old formulas to widely - separated binaries _ if _ the focus is on @xmath5 only . note that the larger errors for small @xmath53 are most likely due to the larger truncation errors affecting those simulations [ see @xcite , sec . iiia ] . however , the situation is very different for the final - spin _ direction_. in particular , fig . [ fig : thetafin ] reports the inclination - angle error @xmath112}\vert$ ] , for all the data in fig . [ fig : afin ] , except those of @xcite , for which the final - spin direction was not published . when considering small - separation binaries ( left panel ) , our new formula performs slightly better than the `` bkl '' and `` @xmath104 '' formulas , but it is not better than the `` fau '' one . indeed , the latter is exact by construction for the 32 binaries of table ii in @xcite , because for such data the final - spin direction was not published and has been here reconstructed using the fau formula . when applied to large - separation binaries ( right panel ) , however , our new formula performs much better than the other ones . this result is not surprising since all the previous formulas predict the same value of @xmath100 for all @xmath65 , as they neglect the precession of the binary s orbital plane . as suggested by @xcite , one can in principle use pn theory to integrate the binary to small separations , and then apply the old formulas . as already mentioned , however , this is impractical , compared to our simple and algebraic expressions for the final spin . also , note that the error in @xmath100 made by the previous formulas at large separations increases for small-@xmath53 binaries . this is again because the previous formulas predict the same @xmath100 for all @xmath65 . therefore , because the correct @xmath100 becomes small for large @xmath65 [ since @xmath113 , the maximum error of the previous formulas is roughly given by their prediction for @xmath100 at small separations , which can be large for small @xmath53 if the angle between @xmath114 and @xmath115 at small separations is large [ because for @xmath116 , @xmath117 and @xmath118 . the very small errors in the predictions of the final - spin direction also provide additional evidence , besides that in fig . [ fig : test_assumption3 ] , of the validity of assumption _ ( iii ) _ , namely that @xmath119 . also , they suggest a correlation between the final - spin direction and the orbital plane when the binary was widely separated . stated differently , by observing @xmath120 , _ e.g. , _ via a jet if this is assumed along @xmath120 , one is virtually `` observing '' @xmath121 and can conclude that the orbital plane at large separations was roughly orthogonal to the final spin . our result could therefore be applied to x - shaped radio sources , for which the origin of the double pair of jets is under debate @xcite . we have derived a new formula predicting the spin of the bh resulting from the merger of two bhs in quasi - circular orbits and having arbitrary initial masses and spins . our derivation is based on a revised set of assumptions and exploits an additional constraint to reduce to only _ four _ the number of undetermined coefficients . the new formula is identical to that proposed in @xcite in the prediction of the final - spin _ norm _ , but is different in the prediction of its _ direction _ , showing a much better agreement with the numerical data . the new formula can be applied to binaries with separations larger than @xmath122 _ without _ any preliminary integration of the pn equations , in contrast with what would be needed by the other formulas proposed in the literature . thus , our formula is particularly suitable for astrophysical and cosmological applications and could provide clues about the relation between the spin of the smbh in the center of agns and the binary s orbital plane well before the merger . 50 apostolatos , t. a. , cutler , c. , sussman , g. j. , & thorne , k. s. 1994 , , 49 , 6274 berti , e. , & volonteri , m. 2008 , , 684 , 822 berti , e. , cardoso , j. , cardoso , v. , & cavagli , m. 2007 , , 76 , 104044 berti , e. , cardoso , v. , gonzalez , j. a. , sperhake , u. , hannam , m. , husa , s. , & brgmann , b. 2007 , , 76 , 064034 berti , e. , cardoso , v. , gonzlez , j. a. , sperhake , u. , & brgmann , b. 2008 , classical and quantum gravity , 25 , 114035 bogdanovic , t. , reynolds , c. s. , & miller , m. c. 2007 , apj , 661 l147 boyle , l. , kesden , m. , & nissanke , s. 2008 , , 100 , 151101 boyle , l. , & kesden , m. 2008 , , 78 , 024017 buonanno , a. , chen , y. , & vallisneri , m. 2003 , , 67 , 104025 buonanno , a. , pan , y. , baker , j. g. , centrella , j. , kelly , b. j. , mcwilliams , s. t. , & van meter , j. r. 2007 , , 76 , 104049 buonanno , a. , kidder , l. e. , & lehner , l. 2008 , , 77 , 026004 buonanno , a. , pan , y. , pfeiffer , h. p. , scheel , m. a. , buchman , l. t. , & kidder , l. e. 2009 , , 79 , 124028 campanelli , m. , lousto , c. o. , zlochower , y. , krishnan , b. , & merritt , d. 2007 , , 75 , 064030 campanelli , m. , lousto , c. , zlochower , y. , & merritt , d. 2007 , , 659 , l5 campanelli , m. , lousto , c. o. , nakano , h. , & zlochower , y. 2009 , 79 , 084010 capetti , a. , zamfir , s. , rossi , p. , bodo , g. , zanni , c. , & massaglia , s. 2002 , , 394 , 39 damour , t. , & nagar , a. 2009 , arxiv:0902.0136 gonzalez , j. a. , sperhake , u. , & bruegmann , b. 2009 , 79 , 124006 . hughes , s. a. , & blandford , r. d. 2003 , , 585 , l101 z kesden , m. 2008 , , 78 , 084030 lousto , c. o. , campanelli , m. , & zlochower , y. 2009 , arxiv:0904.3541 lousto , c. o. , & zlochower , y. 2009 , , 79 , 064018 merritt , d. , & ekers , r. d. 2002 , science , 297 , 1310 miller , j. m. , reynolds , c. s. , fabian , a. c. , miniutti , g. , & gallo , l. c. 2009 , arxiv:0902.2840 pretorius , f. 2007 , `` relativistic objects in compact binaries : from birth to coalescence '' , editors : colpi _ et al . _ , springer verlag , canopus publishing limited , arxiv:0710.1338 rezzolla , l. , dorband , e. n. , reisswig , c. , diener , p. , pollney , d. , schnetter , e. , & szilgyi , b. 2008a , , 679 , 1422 rezzolla , l. , diener , p. , dorband , e. n. , pollney , d. , reisswig , c. , schnetter , e. , & seiler , j. 2008b , , 674 , l29 rezzolla , l. , barausse , e. , dorband , e. n. , pollney , d. , reisswig , c. , seiler , j. , & husa , s. 2008c , , 78 , 044002 rezzolla , l. , 2009 , class . quantum grav . 26 , 094023 scheel , m. a. , boyle , m. , chu , t. , kidder , l. e. , matthews , k. d. , & pfeiffer , h. p. 2009 , , 79 , 024003 tichy , w. , & marronetti , p. 2007 , , 76 , 061502 tichy , w. , & marronetti , p. 2008 , , 78 , 081501

knowledge of the spin of the black hole resulting from the merger of a generic black - hole binary is of great importance for studying the cosmological evolution of supermassive black holes . several attempts have been made to model the spin via simple expressions exploiting the results of numerical - relativity simulations . while these expressions are in reasonable agreement with the simulations , they neglect the precession of the binary s orbital plane , and can not therefore be applied directly _ i.e. , _ without evolving the system to small separations using post - newtonian theory to binaries with separations larger than a few hundred gravitational radii . while not a problem in principle , this may be impractical if the formulas are employed in cosmological merger - trees or n - body simulations , which provide the spins and angular momentum of the two black holes when their separation is of hundreds or thousands of gravitational radii . the formula that we propose is instead built on improved assumptions and gives , for any separation , a very accurate prediction both for the norm of the final spin and for its direction . by comparing with the numerical data , we also show that the final - spin direction is very accurately aligned with the binary s total angular momentum at large separation . hence , observations of the final - spin direction ( _ e.g. , _ via a jet ) can provide information on the binary s orbital plane at large separations and could be relevant , for instance , for studying x - shaped radio sources .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Northern Border States Council Act''. SEC. 2. ESTABLISHMENT OF COUNCIL. (a) Establishment.--There is established a council to be known as the Northern Border States-Canada Trade Council (hereafter in this Act referred to as the ``Council''). (b) Membership.-- (1) Composition.--The Council shall be composed of 24 members consisting of 2 members from each of the following States: (A) Maine. (B) New Hampshire. (C) Vermont. (D) New York. (E) Michigan. (F) Minnesota. (G) Wisconsin. (H) North Dakota. (I) Montana. (J) Idaho. (K) Washington. (L) Alaska. (2) Appointment by state governors.--Not later than 6 months after the date of the enactment of this Act, the Secretary of Commerce (hereafter in this Act referred to as the ``Secretary'') shall appoint two members from each of the States described in paragraph (1) to serve on the Council. The appointments shall be made from a list of nominees submitted by the Governor of each such State. (c) Period of Appointment; Vacancies.--Members shall be appointed for terms that are coterminous with the term of the Governor of the State who nominated the member. Any vacancy in the Council shall not affect its powers, but shall be filled in the same manner as the original appointment. (d) Initial Meeting.--Not later than 30 days after the date on which all members of the Council have been appointed, the Council shall hold its first meeting. (e) Meetings.--The Council shall meet at the call of the Chairperson. (f) Quorum.--A majority of the members of the Council shall constitute a quorum, but a lesser number of members may hold hearings. (g) Chairperson and Vice Chairperson.--The Council shall select a Chairperson and Vice Chairperson from among its members. The Chairperson and Vice Chairperson shall each serve in their respective positions for a period of 2 years, unless such member's term is terminated before the end of the 2-year period. SEC. 3. DUTIES OF THE COUNCIL. (a) In General.--The duties and responsibilities of the Council shall include-- (1) advising the President, the Congress, the United States Trade Representative, the Secretary, and other appropriate Federal and State officials, with respect to-- (A) the development and administration of United States-Canada trade policies, practices, and relations, (B) taxation and regulation of cross-border wholesale and retail trade in goods and services between the United States and Canada, (C) taxation, regulation, and subsidization of agricultural products, energy products, and forest products, and (D) the potential for any United States or Canadian customs or immigration law or policy to result in a barrier to trade between the United States and Canada, (2) monitoring the nature and cause of trade issues and disputes that involve one of the Council-member States and either the Canadian Government or one of the provincial governments of Canada; and (3) if the Council determines that a Council-member State is involved in a trade issue or dispute with the Government of Canada or one of the provincial governments of Canada, making recommendations to the President, the Congress, the United States Trade Representative, and the Secretary concerning how to resolve the issue or dispute. (b) Response to Requests by Certain People.-- (1) In general.--Upon the request of the United States Trade Representative, the Secretary, a Member of Congress who represents a Council-member State, or the Governor of a Council-member State, the Council shall review and comment on-- (A) reports of the Federal Government and reports of a Council-member State government concerning United States-Canada trade, (B) reports of a binational panel or review established pursuant to chapter 19 of the North American Free Trade Agreement concerning the settlement of a dispute between the United States and Canada, (C) reports of an arbitral panel established pursuant to chapter 20 of the North American Free Trade Agreement concerning the settlement of a dispute between the United States and Canada, and (D) reports of a panel or Appellate Body established pursuant to the General Agreement on Tariffs and Trade concerning the settlement of a dispute between the United States and Canada. (2) Determination of scope.--Among other issues, the Council shall determine whether a trade dispute between the United States and Canada is the result of action or inaction on the part of the Federal Government of Canada or a provincial government of Canada. (c) Council-Member State.--For purposes of this section, the term ``Council-member State'' means a State described in section 2(b)(1) which is represented on the Council established under section 2(a). SEC. 4. REPORT TO CONGRESS. Not later than 2 years after the date of the enactment of this Act and at the end of each 2-year period thereafter, the Council shall submit a report to the President and the Congress which contains a detailed statement of the findings, conclusions, and recommendations of the Council. SEC. 5. POWERS OF THE COUNCIL. (a) Hearings.--The Council may hold such hearings, sit and act at such times and places, take such testimony, and receive such evidence as the Council considers advisable to carry out the provisions of this Act. Notice of Council hearings shall be published in the Federal Register in a timely manner. (b) Information From Federal Agencies.--The Council may secure directly from any Federal department or agency such information as the Council considers necessary to carry out the provisions of this Act. Upon the request of the Chairperson of the Council, the head of such department or agency shall furnish such information to the Council. (c) Postal Services.--The Council may use the United States mails in the same manner and under the same conditions as other departments and agencies of the Federal Government. (d) Gifts.--The Council may accept, use, and dispose of gifts or donations of services or property. SEC. 6. COUNCIL PERSONNEL MATTERS. (a) Members To Serve Without Compensation.--Except as provided in subsection (b), members of the Council shall receive no compensation, allowances, or benefits by reason of service to the Council. (b) Travel Expenses.--The members of the Council 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 Council. (c) Staff.-- (1) In general.--The Chairperson of the Council may, without regard to the civil service laws, appoint and terminate an executive director and such other additional personnel as may be necessary to enable the Council to perform its duties. The employment of an executive director shall be subject to confirmation by the Council and the Secretary. (2) Compensation.--The Chairperson of the Council may fix the compensation of the executive director and other personnel without regard to the provisions of chapter 51 and subchapter III of chapter 53 of title 5, United States Code, relating to classification of positions and General Schedule pay rates, except that the rate of pay for the executive director and other personnel may not exceed the rate payable for level V of the Executive Schedule under section 5316 of such title. (d) Detail of Government Employees.--Any Federal Government employee may be detailed to the Council without reimbursement, and such detail shall be without interruption or loss of civil service status or privilege. (e) Procurement of Temporary and Intermittent Services.--The Chairperson of the Council may procure temporary and intermittent services under section 3109(b) of title 5, United States Code, at rates for individuals which do not exceed the daily equivalent of the annual rate of basic pay prescribed for level V of the Executive Schedule under section 5316 of such title. (f) Office Space.--The Secretary shall provide office space for Council activities and for Council personnel. SEC. 7. TERMINATION OF THE COUNCIL. The Council shall terminate on the date that is 54 months after the date of the enactment of this Act and shall submit a final report to the President and the Congress under section 4 at least 90 days before such termination. SEC. 8. AUTHORIZATION OF APPROPRIATIONS. (a) In General.--There are authorized to be appropriated from amounts made available by appropriations to the Department of Commerce an amount not to exceed $250,000 for fiscal year 1996 and for each fiscal year thereafter to the Council to carry out the provisions of this Act. (b) Availability.--Any sums appropriated under the authorization contained in this section shall remain available, without fiscal year limitation, until expended.

Northern Border States Council Act - Establishes the Northern Border States-Canada Trade Council. Sets forth the duties of the Council, including: (1) advising the President, the Congress, the United States Trade Representative, the Secretary of Commerce, and other appropriate Federal and State officials with respect to the administration of U.S.-Canada trade policies, taxation of trade in goods and services, and customs and immigration matters; (2) monitoring trade issues and disputes that involve one of the Council-member States and either the Canadian Government or one of Canada's provinces; and (3) making recommendations with respect to such disputes. Authorizes appropriations.

SECTION 1. SHORT TITLE. This Act may be cited as the ``The HAMP Termination Act of 2011''. SEC. 2. CONGRESSIONAL FINDINGS. The Congress finds the following: (1) According to the Department of the Treasury-- (A) the Home Affordable Modification Program (HAMP) is designed to ``help as many as 3 to 4 million financially struggling homeowners avoid foreclosure by modifying loans to a level that is affordable for borrowers now and sustainable over the long term''; and (B) as of February 2011, only 607,600 active permanent mortgage modifications were made under HAMP. (2) Many homeowners whose HAMP modifications were canceled suffered because they made futile payments and some of those homeowners were even forced into foreclosure. (3) The Special Inspector General for TARP reported that HAMP ``benefits only a small portion of distressed homeowners, offers others little more than false hope, and in certain cases causes more harm than good''. (4) Approximately $30 billion was obligated by the Department of the Treasury to HAMP, however, approximately only $840 million has been disbursed. (5) Terminating HAMP would save American taxpayers approximately $1.4 billion, according to the Congressional Budget Office. SEC. 3. TERMINATION OF AUTHORITY. Section 120 of the Emergency Economic Stabilization Act of 2008 (12 U.S.C. 5230) is amended by adding at the end the following new subsection: ``(c) Termination of Authority To Provide New Assistance Under the Home Affordable Modification Program.-- ``(1) In general.--Except as provided under paragraph (2), after the date of the enactment of this subsection the Secretary may not provide any assistance under the Home Affordable Modification Program under the Making Home Affordable initiative of the Secretary, authorized under this Act, on behalf of any homeowner. ``(2) Protection of existing obligations on behalf of homeowners already extended an offer to participate in the program.--Paragraph (1) shall not apply with respect to assistance provided on behalf of a homeowner who, before the date of the enactment of this subsection, was extended an offer to participate in the Home Affordable Modification Program on a trial or permanent basis. ``(3) Deficit reduction.-- ``(A) Use of unobligated funds.--Notwithstanding any other provision of this title, the amounts described in subparagraph (B) shall not be available after the date of the enactment of this subsection for obligation or expenditure under the Home Affordable Modification Program of the Secretary, but should be covered into the General Fund of the Treasury and should be used only for reducing the budget deficit of the Federal Government. ``(B) Identification of unobligated funds.--The amounts described in this subparagraph are any amounts made available under title I of the Emergency Economic Stabilization Act of 2008 that-- ``(i) have been allocated for use, but not yet obligated as of the date of the enactment of this subsection, under the Home Affordable Modification Program of the Secretary; and ``(ii) are not necessary for providing assistance under such Program on behalf of homeowners who, pursuant to paragraph (2), may be provided assistance after the date of the enactment of this subsection. ``(4) Study of use of program by members of the armed forces, veterans, and gold star recipients.-- ``(A) Study.--The Secretary shall conduct a study to determine the extent of usage of the Home Affordable Modification Program by, and the impact of such Program on, covered homeowners. ``(B) Report.--Not later than the expiration of the 90-day period beginning on the date of the enactment of this subsection, the Secretary shall submit to the Congress a report setting forth the results of the study under subparagraph (A) and identifying best practices, derived from studying the Home Affordable Modification Program, that could be applied to existing mortgage assistance programs available to covered homeowners. ``(C) Covered homeowner.--For purposes of this subsection, the term `covered homeowner' means a homeowner who is-- ``(i) a member of the Armed Forces of the United States on active duty or the spouse or parent of such a member; ``(ii) a veteran, as such term is defined in section 101 of title 38, United States Code; or ``(iii) eligible to receive a Gold Star lapel pin under section 1126 of title 10, United States Code, as a widow, parent, or next of kin of a member of the Armed Forces person who died in a manner described in subsection (a) of such section. ``(5) Publication of member availability for assistance.-- Not later than 5 days after the date of the enactment of this subsection, the Secretary of the Treasury shall publish to its Website on the World Wide Web in a prominent location, large point font, and boldface type the following statement: `The Home Affordable Modification Program (HAMP) has been terminated. If you are having trouble paying your mortgage and need help contacting your lender or servicer for purposes of negotiating or acquiring a loan modification, please contact your Member of Congress to assist you in contacting your lender or servicer for the purpose of negotiating or acquiring a loan modification.'. ``(6) Notification to hamp applicants required.-- ``(A) In general.--Not later than 30 days after the date of the enactment of this subsection, the Secretary of the Treasury shall inform each individual who applied for the Home Affordable Modification Program and will not be considered for a modification under such Program due to termination of such Program under this subsection-- ``(i) that such Program has been terminated; ``(ii) that loan modifications under such Program are no longer available; ``(iii) of the name and contact information of such individual's Member of Congress; and ``(iv) that the individual should contact his or her Member of Congress to assist the individual in contacting the individual's lender or servicer for the purpose of negotiating or acquiring a loan modification.''. SEC. 4. SENSE OF CONGRESS. The Congress encourages banks to work with homeowners to provide loan modifications to those that are eligible. The Congress also encourages banks to work and assist homeowners and prospective homeowners with foreclosure prevention programs and information on loan modifications. Passed the House of Representatives March 29, 2011. Attest: KAREN L. HAAS, Clerk.

HAMP Termination Act of 2011 - Amends the Emergency Economic Stabilization Act of 2008 (EESA) to terminate the authority of the Secretary of the Treasury to provide new mortgage modification assistance under the Home Affordable Modification Program (HAMP), except with respect to existing obligations on behalf of homeowners already extended an offer to participate in the program. Declares unavailable after the enactment of this Act for obligation or expenditure under HAMP any amounts made available for HAMP under EESA title I that: (1) have been allocated for use but not yet obligated, and (2) are not necessary for providing HAMP assistance on behalf of those homeowners already extended an offer to participate in HAMP. Urges that such amounts be covered into the General Fund of the Treasury for use only in reducing the budget deficit of the federal government. Directs the Secretary to study: (1) the extent to which HAMP is used by homeowners who are active duty members of the Armed Forces (or their spouses or parents), veterans, or Gold Star-eligible widows, parents, or next of kin of Armed Forces members who died in military operations; and (2) the impact of the program on them. Requires the Secretary to publish on the departmental website a statement as to: (1) termination of HAMP; and (2) the availability of a Member of Congress to assist any borrower having trouble paying a mortgage and needing help contacting the borrower's lender or servicer to negotiate or acquire a loan modification. Requires the Secretary to give notice of this information to each individual who applied for HAMP and will not be considered for a mortgage modification because of the program's termination. Declares that Congress encourages banks to work with homeowners to: (1) provide loan modifications to those that are eligible, and (2) assist them as well as prospective homeowners with foreclosure prevention programs and information on loan modifications.

WASHINGTON (AP) — The Obama administration's approval of the final permit to drill for oil in the Arctic Ocean clashes with the message President Barack Obama will deliver when he visits Alaska to emphasize the dangers of climate change, some environmental groups say. FILE - In this April 17, 2015 file photo, with the Olympic Mountains in the background, a small boat crosses in front of the Transocean Polar Pioneer, a semi-submersible drilling unit that Royal Dutch... (Associated Press) FILE - In this May 14, 2015, file photo, the oil drilling rig Polar Pioneer is towed toward a dock in Elliott Bay in Seattle. The rig is the first of two drilling rigs Royal Dutch Shell is outfitting... (Associated Press) As much as the groups praise Obama for his overall body of work — from stricter fuel-efficiency standards to regulations aimed at reducing greenhouse gas emissions from power plants — they consider the approval of exploratory drilling in the Arctic a stain on his environmental legacy that will send a mixed message to other countries about the seriousness of confronting global warming. The burning of fossil fuels causes more greenhouse gases to build up in the atmosphere. Some groups would prefer leaving the oil in the ground and not tempting the harsh environmental conditions that could hinder the response to any potential spill. "It sends a terrible signal to the rest of the world for the United States to be using public resources to promote that development," said Niel Lawrence of the Natural Resources Defense Council. "We have to make clear to the rest of the world that we are all in on a clean energy future. And we've got to stop giving the rest of the world license to go exploring by permitting Shell to do it." The administration previously allowed Shell to begin drilling only the top sections of two wells in the Chukchi Sea because key equipment, called a capping stack, was stuck on a vessel that needed repair in Portland, Oregon. Now, Shell is free to drill into oil-bearing rock, estimated at 8,000 feet below the ocean floor. The U.S. Geological Survey estimates that U.S. Arctic waters hold 26 billion barrels of recoverable oil. Shell is eager to explore in a basin that company officials say could be a "game changer" for domestic production. Obama, who is scheduled to visit Alaska later this month, says he is mindful of the dangers of offshore drilling, particularly given the 2010 Deepwater Horizon oil spill. "When it can be done safely and appropriately, U.S. production of oil and natural gas is important," he said at a news conference earlier this year. "I would rather us, with all the safeguards and standards that we have, be producing our oil and gas, rather than importing it, which is bad for our people, but is also potentially purchased from places that have much lower environmental standards than we do." When asked whether the administration was sending contradictory messages, White House spokesman Frank Benenati said the administration has invested heavily in renewable energy so that the nation can transition off fossil fuels. "But it's also true that we cannot make that transition overnight, which is why we have taken steps to ensure safe and responsible development of our domestic energy resources that benefits our economy and enhances global energy security, with safety remaining paramount," Benenati said. The administration's approval of Shell's exploration efforts has done little to stem criticism from congressional Republicans and industry officials who have often accused it of hindering oil and gas production on federal lands. At the same time, the go-ahead has upset a key base of his support. "It's perplexing and depressing, quite frankly, to hear President Obama say he wants to fix climate change but then approve Arctic drilling. It's like a doctor diagnosing a patient but then refusing to write a prescription," said Rebecca Noblin, Alaska director for the Center for Biological Diversity. Lawrence prefaced his criticism of the go-ahead to Shell by saying Obama has done more to fight climate change than "any other leader in world history." In his visit to Alaska, Obama is expected to stress the dangers of climate change. He says Alaskans are on the front lines of the problem. ___ Associated Press writer Dan Joling in Anchorage, Alaska, contributed to this report. ||||| CHILMARK, Mass. (AP) — President Barack Obama says he'll use his upcoming trip to the Arctic region to press world leaders to do more to fight climate change. Obama plans to travel to Alaska in late August. He'll speak to a global Arctic leadership summit in Anchorage and also travel north to the Arctic. The White House says it's the first visit by a sitting president to the Alaskan Arctic. Obama says in a video posted to social media that he's going because Alaskans are on the front lines of climate change. He's pointing to melting glaciers and permafrost and says entire villages and ways of life are threatened. Obama's visit comes as he works to build support for controversial steps he's taking to slow global warming, including unprecedented pollution limits on power plants. ||||| An activist watches while hanging from the St. Johns bridge as the Royal Dutch Shell PLC icebreaker Fennica heads upriver in Portland, Ore., Thursday, July 30, 2015. The icebreaker is a vital part of... (Associated Press) Activists hang off the St. Johns Bridge to protest Shell Oil's drilling in the Arctic, in Portland, Ore., Wednesday, July 29, 2015. The thirteen protesters dangled from the bridge while another 13 remained... (Associated Press) Royal Dutch Shell PLC icebreaker Fennica heads upriver in Portland, Ore., Thursday, July 30, 2015. The icebreaker is a vital part of Shell's exploration and spill-response plan off Alaska's northwest... (Associated Press) Activists unfurl colored banners while hanging from the St. Johns bridge in Portland, Ore., Wednesday, July 29, 2015, to protest the departure of Royal Dutch Shell PLC icebreaker Fennica, which is in... (Associated Press) Royal Dutch Shell PLC icebreaker Fennica, sits in dry dock at the Port of Portland in Portland, Ore., Wednesday, July 29, 2015, close to where activists placed themselves hanging from the St. Johns bridge... (Associated Press) Activists hang off the St. Johns Bridge to protest Shell Oil's drilling in the Arctic, in Portland, Ore., Wednesday, July 29, 2015. The thirteen protesters dangled from the bridge while another 13 remained... (Associated Press) Protesters on St. Johns Bridge and kayakers on the Willamette River below have been blocking the icebreaker from heading to the Arctic for a drill operation. The icebreaker Fennica arrived in Portland for repairs last week. The vessel was damaged earlier this month in the Aleutian Islands when it struck an underwater obstruction, tearing a gash in its hull. It started its journey to the Arctic early Thursday before stalling in the face of 13 dangling activists linked by ropes. It then turned around and inched its way back to Vigor Industrial's dry dock, delighting those gathered on shore in the city known for environmentalism. "I think it's inspirational," Portland resident Lisa Szot told The Oregonian. "It's a really beautiful protest." The U.S. Coast Guard warned the danglers they were breaking the law, but took no action. Petty Officer 1st Class George Degener said the agency did not tell those aboard the icebreaker to turn around. "I don't know what led the master and the pilot on board to come to that decision," he said. The icebreaker is a key part of Shell's exploration and spill-response plan off Alaska's northwest coast. It protects Shell's fleet from ice and carries equipment that can stop gushing oil. Environmentalists hope to delay the ship long enough for winter weather to prevent Shell from drilling until 2016. By that time, they hope the Obama administration has a change-of-heart on the issue. "There is no Plan B, just as there is no Planet B; we have no intention of moving until President Obama rescinds the permit for Shell to drill in the Arctic," said Daphne Wysham of the Center for Sustainable Economy. Shell did not immediately comment Thursday. Portland police closed the bridge to traffic during the standoff. It was reopened shortly after the icebreaker reversed course. The activists say they have water and food for the long haul. They also have their phones to stay in the social-media loop. "The fennica is headed back to its dock where it belongs — not the arctic! #ShellNo," tweeted Dan Cannon, a Greenpeace activist dangling from the bridge. ||||| BSEE Approves Updated Permit for Exploration Activities in Arctic Waters Under Rigorous Safety Requirements 08/17/2015 WASHINGTON — After extensive review and under a robust array of safety requirements, Bureau of Safety and Environmental Enforcement (BSEE) Director Brian Salerno today announced that Shell has received approval of one Application for Permit to Modify (APM) to conduct exploratory drilling activities into potential oil-bearing zones offshore Alaska at one of the wells at the Burger Prospect, Burger J. The company remains limited to the top section of the Burger V well. Shell submitted an APM on August 6 to modify the Burger J Application for Permit to Drill (APD), which previously restricted Shell from drilling into oil-bearing zones since a capping stack was not on hand and deployable within 24 hours, as required by BSEE. A capping stack is a critical piece of emergency response equipment designed to shut in a well in the unlikely event of a loss of well control. The capping stack, staged on the vessel M/V Fennica, is now in the region and capable of being deployed within 24 hours. “Activities conducted offshore Alaska are being held to the highest safety, environmental protection, and emergency response standards,” said Salerno. “Now that the required well control system is in place and can be deployed, Shell will be allowed to explore into oil-bearing zones for Burger J. We will continue to monitor their work around the clock to ensure the utmost safety and environmental stewardship.” Shell is still prohibited from simultaneous drilling at Burger J and V, in accordance with the approved APDs, which define limitations related to marine mammal protection consistent with requirements established by the U.S. Fish and Wildlife Service (USFWS). Consistent with regulatory requirements, a USFWS Letter of Authorization (LOA) issued on June 30 requires Shell to maintain a minimum spacing of 15 miles between active drill rigs during exploration activities to avoid significant effects on walruses in the region. Under the LOA, Shell is also required to have trained wildlife observers on all drilling units and support vessels to minimize impacts to protected species. Shell must stay within explicitly outlined vessel operating speeds and report daily regarding all vessel transits. To ensure compliance with this and other conditions, BSEE safety inspectors have been present on the drilling units Noble Discoverer and Transocean Polar Pioneer 24 hours a day, seven days a week to provide continuous oversight and monitoring of all approved activities. The inspectors are authorized to take immediate action to ensure compliance and safety, including cessation of all drilling activities, if necessary. BSEE experts have been engaged in thorough inspections of both drilling units and Shell’s response equipment. The Burger Prospect is located in about 140 feet of water, 70 miles northwest of the village of Wainwright. BSEE’s close oversight of drilling operations in the Chukchi Sea this year is consistent with its continuing efforts over the past five years to upgrade safety standards to improve the safety of offshore oil and gas development. In addition, building on the lessons learned from Shell’s 2012 drilling operations in the offshore Arctic and incorporating the recommendations of a Departmental review of those activities, the Bureau of Ocean Energy Management (BOEM) on May 11, 2015, provided conditional approval of Shell’s Exploration Plan, which established numerous additional stringent safety requirements: All phases of an offshore Arctic program – preparations, drilling, maritime and emergency response operations – must be integrated and subject to strong operator management and government oversight, as detailed in Shell’s Integrated Operations Plan; A shortened drilling season to allow time for open-water emergency response and relief rig operations late in the drilling season before projected ice encroachment; Capping stack must be pre-staged and available for use within 24 hours; A tested subsea containment system must be deployable within eight days; The capability to drill a same season relief well; A robust suite of measures to avoid and minimize adverse impacts to marine mammals and their habitat, impacts to Native subsistence activities, and other environmental impacts; and Drilling units and their supporting vessels must depart the Chukchi Sea at the conclusion of each exploration drilling season. The Department has also published proposed regulations to ensure that future exploratory drilling activities on the U.S. Arctic Outer Continental Shelf are done safely and responsibly, subject to strong and proven operational standards and Shell’s Chukchi Sea operations are being held to many of standards in the proposed regulations. The APM and decision letter can be found here. ||||| Greenpeace activists demonstrate on March 16, 2012 in the port of Helsinki as other activists occupy a Shell-contracted icebreaker preparing to sail for the Arctic. | Getty ENERGY & ENVIRONMENT Greens decry Obama’s Shell game “The president cannot have it both ways,” Greenpeace says after the company wins an Arctic drilling permit. President Barack Obama crushed greens’ hearts Monday by giving Shell the final go-ahead to drill for oil in Alaska’s Arctic waters, just two weeks after he thrilled them by issuing his landmark regulations on climate change. In the long run, Obama’s successors will determine whether the industry can tap Alaska’s prized offshore oil — and one 2016 contender, Hillary Clinton, has expressed “doubts” about opening the Arctic to drilling. But it was Obama’s Interior Department that gave Shell its nod Monday, in the face of an opposition campaign that has seen activists dangling from a bridge in Oregon and swarming the company’s Arctic-bound rig with kayaks to try to block the project. Story Continued Below For greens, the announcement was even more galling because it arrived only two weeks before Obama is due to talk climate change during his first visit to Alaska’s Arctic. “The president cannot have it both ways,” Greenpeace USA Executive Director Annie Leonard said. “Announcing a tour of Alaska to highlight climate change days before giving Shell the final approval to drill in the Arctic ocean is deeply hypocritical.” Monday’s decision was the latest pro-oil move from a president who has steadily offered mixed signals on fossil fuels throughout his presidency. Obama has repeatedly cheered the economic benefits of the domestic oil and gas boom while moving to open up parts the U.S. coast to possible offshore drilling — but he has also pushed to strip away billions of dollars in industry tax breaks, championed big spending on wind and solar power and, at the very least, dragged out his decision on the Keystone XL oil pipeline for more than six years. Even the Interior Department’s approval of Shell’s Arctic plans was no slam-dunk win for the company, which has already spent $7 billion on the risky search for oil deposits beneath the Arctic waters. The new permit is good for several weeks only, and the oil giant doesn’t expect to start production in the Chukchi Sea until 2030, long after its current lease expires in 2020. Monday’s announcement also came with some tighter safety restrictions than Shell had faced before its last, ill-fated attempt at Arctic offshore drilling in 2012, when a series of pratfalls culminated in a rig breaking free and running aground while being towed out of Alaska on New Year’s Eve. This time, other major oil companies are watching to see whether Shell succeeds in its quest for oil off the Alaska coast, which will have the U.S. join the ranks of Arctic nations such as Norway and Russia that are exploring for new energy deposits as the region’s ice cover recedes. Even as climate activists lamented the Interior Department’s decision, they vowed to campaign even harder to convince Obama and the next president that Shell has no business in the Arctic. Keeping the company out of the Arctic is “going to be a real battle, because Shell defines irresponsible and they will keep coming for this oil,” climate activist and author Bill McKibben said by email. Given the “clear” evidence that burning Arctic crude would worsen global warming, he added, “there’s at least a chance, long term, that reason will prevail. Only, of course, if reason comes with a movement to back it up, which all of us will do our best to keep providing.” Shell, playing the long game, said it aims to prove the viability of its Arctic drilling effort. “We remain committed to operating in a safe, environmentally responsible manner and look forward to evaluating what could potentially become a national energy resource base,” Shell spokesman Curtis Smith said by email. Shell CEO Ben van Beurden has said he anticipates production from Alaskan leases to start in 2030, which would require an extension of its current Chukchi lease term. Senate Energy and Natural Resources Chairwoman Lisa Murkowski (R-Alaska) is working to make that possible: She added language allowing Interior to give Alaskan drillers another decade to explore to a bill she’s sponsoring that would lift the United States’ ban on oil exports. Some greens are optimistic that Shell’s plans will still fail. “It may well be that action on climate is the reason these resources aren’t developed,” said Mike LeVine, senior counsel at the green group Oceana. “It may be that [the oil is] not there — and more attention to the issue helps on all those fronts.” The Chukchi Sea is estimated to hold more recoverable oil than any coastal area outside the Gulf of Mexico. Shell last got permission to drill into its oil-bearing zones between 1989 and 1991, when it ended its operations after discovering only natural gas. And since its missteps in 2012, the company has faced a colorful campaign by eco-activists, who have tried to obstruct its rig with a flotilla of kayaks as it left harbor in Seattle, dangled from a bridge in Oregon to block its icebreaker, and issued viral videos as well as circulating old-fashioned legal petitions. “They see this season and next season as an opportunity to prove to their shareholders” that its Arctic leases are economically viable, Alaska Wilderness League Executive Director Cindy Shogan said, while “we see this season and next season as showing the Obama administration” that allowing further drilling in the area is a mistake. The Obama administration insisted on Monday that it had thoroughly vetted the oil company’s operations before giving its approval. “Activities conducted offshore Alaska are being held to the highest safety, environmental protection, and emergency response standards,” Brian Salerno, director of the Interior Department’s Bureau of Safety and Environmental Enforcement said in a statement. But greens who implored Obama to keep the oil industry out of Arctic waters said several elements of Shell’s new drilling permit stronger are actually weaker on safety than the 2012 version. Those include testing requirements for key safety equipment, which now need to be performed every two weeks rather than every week, and less stringent air quality standards. Clinton, who is facing skepticism among many on the environmental left, appeared to side with greens on July 29 by telling a New Hampshire television station that “I have doubts about whether we should continue drilling in the Arctic.” Clinton has previously said she favors shielding more areas from drilling, but has opposed banning it on all public lands and waters. Activists livid after BSEE approved Shell’s plans are highly likely to press her to move further left on Arctic oil and gas. Shell got Interior’s green light to begin work in the Chukchi last month, but that permit blocked the company from drilling beyond 3,000 feet below the surface, short of the oil- and gas-bearing zones, until a damaged icebreaker ship could return to the area with required safety equipment. The repaired vessel returned to the Arctic in recent days, setting the stage for a final OK of Shell’s drilling plan. The approval is good for this year’s summer season, set to end in late September. Shell’s troubled 2012 drilling effort stopped short of oil- and gas-bearing zones in the Chukchi after Interior denied the permits, citing the failure of required safety equipment. An Interior review released in 2013 attributed the stumble to “shortcomings in Shell’s management and oversight of key contractors.” The company drilled four exploration wells in the Chukchi between 1989 and 1991, according to Interior, including one located in the same Burger Prospect area off the Alaskan coast that Shell is seeking to tap this year. That early effort was abandoned after it yielded mostly natural gas, though newer geological data shows the likelihood that oil is also present. Monday’s approval from Interior allows Shell to expand drilling at one well in the Burger area. The company remains barred from deeper access to a second well in the prospect — it is prohibited from drilling both prospects simultaneously, since both lie within a buffer zone that the administration previously established to protect walruses. Shell’s current Alaskan offshore drilling program carries particular urgency for the company as it slashes spending elsewhere during a historic downturn in oil prices. It’s also crucial for Alaska, where the swoon in crude prices has crunched the state’s budgets and heightened the importance of new discoveries, even in federal waters that don’t yield direct royalty money for the state treasury. Arctic drilling also stands to prove a crucial component of Obama’s climate legacy, despite the brighter spotlight his aides hope to shine on EPA emissions regulations. But environmentalists are aware of how much 2016 matters for their battle. The Sierra Club’s lands protection director, Athan Manuel, said that “the next president will have big influence in whether a production platform is ever placed” in the Arctic, even as he promised activists wouldn’t give up on pressuring Obama to halt drilling off the Alaskan coast. “It’s just not something you’d expect from a Democratic president.” ||||| WASHINGTON For a leader who has made fighting climate change a priority, President Barack Obama's decision to approve Royal Dutch Shell's return to oil and gas exploration off Alaska was seen by many environmentalists as a contradiction. On Tuesday, his administration upheld a 2008 Arctic lease sale, clearing an important hurdle for Shell. The Interior Department will now consider the company's drilling plan, which could take 30 days. But Shell, which has already spent about $6 billion exploring the Arctic, expects to return to polar waters this summer and is already moving oil rigs to Alaska. Meanwhile, environmentalists pointed to Shell's mishaps in the region in 2012 when a massive rig ran aground and the company was fined for pollution, raising questions about Obama's decision: Isn't Obama opposed to oil extraction in sensitive areas? While his administration has championed renewable energy, Obama has never disavowed the need for oil and gas in the U.S. energy mix. His approach has been to balance new regulations on high-carbon industries with an appreciation for the economic benefits of the domestic oil and gas boom. To counter critics, Obama can point to his January proposal to prohibit drilling on 1.4 million acres of the Alaska National Wildlife Refuge. In addition, drilling offshore Alaska is in relatively shallow waters and would need less pressure than deepwater drilling in the Gulf of Mexico, home to the 2010 BP Deepwater Horizon oil spill. The special U.S. envoy to the Arctic, Robert Papp, said this week that Shell understands the importance of taking necessary precautions after its Kulluk rig ran aground in 2012. "They should be OK," Papp said. With global crude prices low, why is Shell going to a remote region in search of hard-to-extract oil and gas? While oil prices have fallen by more than half since last summer, offshore Arctic drilling may not produce substantial new reserves for decades - when onshore shale deposits may start to wane. The fracking revolution in North Dakota and Texas has led to the highest U.S. oil output since the early 1970s, but nobody knows how long shale will continue to produce at high rates. "The trick of Arctic energy development is that the time horizons are extraordinary long, some 10 to 30 years from when companies start these complex deals to even seeing when those resources would get to market," said Heather Conley, an analyst at the Center for Strategic and International Studies. Shell will conduct tests to see how much oil and gas are in the Chukchi and Beaufort Seas. The Arctic is estimated to contain about 20 percent of the world's undiscovered oil and gas, 34 million barrels of oil in U.S. waters alone. Only Russia has bigger deposits. The National Petroleum Council, a group led by oil companies that advises the Energy Department, said in an assessment of Arctic potential last week that the region will boost U.S. energy security. (bit.ly/1Fe08jp) Won't this add to carbon emissions at the same time Washington is trying to get the world to cut them? If fracking in the continental United States declines, the government could argue that it is simply replacing barrels it used to produce elsewhere. The Arctic also has a lot of gas that is lower in emissions when burned. Depending on how markets shape up, energy companies could be drilling for more gas than oil in the Arctic. Could Obama be acting for strategic reasons? Other countries are present in the Arctic. Russia is exploring its northern waters, although Western sanctions have forced Shell competitor Exxon Mobil to withdraw from partnerships there. China and India are also interested in joining partnerships to drill in the Arctic. But the United States has a major infrastructure advantage: Due to a decline of Alaskan oil output, the Trans Alaskan pipeline is only operating at 25 percent of capacity and could serve as a conduit for new oil finds. "The Alaska pipeline would be ecstatic to get another customer," said Lou Pugliaresi, president of the Energy Policy Research Foundation, noting that the Russian Arctic's lack of infrastructure could make projects slower to develop. (Reporting by Timothy Gardner; Editing by Bruce Wallace and Leslie Adler) ||||| SEATTLE — The U.S. Coast Guard temporarily detained two dozen protesters who formed a blockade with kayaks and other vessels Monday to try to stop Royal Dutch Shell's drill rig as it left Seattle on its way to explore for oil in the Arctic Ocean. The protesters were scooped up from the water because they were violating the safety zone around the Polar Pioneer, which departed around 6 a.m., Coast Guard Lt. Dana Warr said. They were released after receiving violation notices that carry fines, the Coast Guard said. Some protesters had indicated they hoped to confront the rig off Port Townsend on Washington's Olympic Peninsula. However, Petty Officer Amanda Norcross said late Monday night that a gale warning was in effect in that area until Tuesday morning. She said the Coast Guard had not had any more interactions with protesters there. A marine traffic website showed the vessel under way off Port Townsend late Monday. About a dozen "kayaktivists" paddled out around 4 a.m. Monday to try to prevent the 400-foot-long rig from leaving Seattle, said Cassady Sharp, a Greenpeace spokeswoman. Several dozen supporters in kayaks and canoes lined up behind them, she said. Seattle Councilman Mike O'Brien was among those detained. He and others in kayaks paddled into Seattle's picturesque Elliott Bay before dawn to oppose Shell's plans to open a new frontier of fossil fuel exploration off Alaska's coast. "That monstrous rig is headed to the Arctic to attempt to do something unconscionable," he said in a text message as he was processed by the Coast Guard at its offices. "I had done everything I know how to do as a citizen, an activist, and as a councilmember to stop Shell from drilling in the Arctic." The petroleum giant has been using the port to load drilling rigs and a fleet of support vessels with supplies and personnel before spending the brief Arctic summer in the Chukchi Sea, which stretches north from the Bering Strait between Alaska and Russia. Shell spokesman Curtis Smith said Monday that the vessels are on the way to Alaska. "We remain committed to operating in a safe, environmentally responsible manner and look forward to exploring our Chukchi leases in the weeks to come," he said in an email. The Coast Guard picked up Kelly Mears, 28, in a yellow double kayak as he and others unfurled a massive "Shell No" banner on the water. "Ultimately, I think that it's pretty negligent decision to allow the vessel to drill in the Arctic," said Mears, who came from South Carolina in April to participate in a series of protests. "My personal moral compass wasn't allowing me to stand idly by and bemoan it as something that we can't escape from." Monday's blockade was the latest protest since the Polar Pioneer arrived in Seattle in May. Activists say they are concerned about the risks of an oil spill in the remote Arctic waters and the effects that tapping new oil and gas reserves will have on global warming. Activists also have chained themselves twice to a support ship in Bellingham, north of Seattle. They have tried to block entrances to the Seattle terminal where the rig was loaded. Several have been arrested. Officials in Alaska, including the governor, have touted the economic benefits that drilling could bring there and to the Pacific Northwest. The U.S. Geological Survey estimates Arctic offshore reserves at 26 billion barrels of recoverable oil and 130 trillion cubic feet of natural gas. Shell says developing these reserves could increase domestic oil supplies by more than 1 million barrels a day.

– President Obama has disappointed a slew of environmental activists by giving Shell the green light yesterday to drill deeper in the Arctic for oil, Quartz reports. The approval issued by the Bureau of Safety and Environmental Enforcement expands the oil company's current permissions, allowing it to drill even further down into the Chukchi Sea after proper safety gear was installed, the Hill reports. But the decision is being decried by already active critics as the president's trip to Alaska to talk about climate change looms later this month. Greenpeace USA's executive director calls the move "deeply hypocritical," per Politico. "President Obama should know better—Shell has no business in our Arctic Ocean, and he will bear responsibility for the damage that Shell wreaks there," a rep for Friends of the Earth says, while the executive director of the Sierra Club adds the decision "goes against science, the will of the people and common sense," per the Hill. An April Reuters article proffered theories why this may be happening: For one, onshore shale oil production may start to fall off in a few decades, and it may take that long to build up sufficient reserves of Arctic oil. Energy companies could also reap the benefits of lower-emissions gas in the region, and the president may be able to gain a strategic advantage over Russia and China by starting now. A Shell rep tells Politico: "We remain committed to operating in a safe, environmentally responsible manner and look forward to evaluating what could potentially become a national energy resource base." That's not swaying environmentalists. "President Obama is willing to allow the pristine Chukchi Sea to become an energy sacrifice zone," the Friends of the Earth rep says, per Quartz. (A New York Times writer likens the decision to "tobacco companies … applying for permission to put cigarette machines in cancer wards.")

SECTION 1. SHORT TITLE. This Act may be cited as the ``National Estuarine Reserve System Act of 2003''. SEC. 2. ESTABLISHMENT OF NATIONAL ESTUARINE RESERVE SYSTEM. (a) Policy.--Section 303 of the Coastal Zone Management Act of 1972 (16 U.S.C. 1452) is amended-- (1) in paragraph (5) by striking ``and'' after the semicolon; (2) in paragraph (6) by striking the period at the end and inserting ``; and''; and (3) by adding at the end the following: ``(7) to use the National Estuarine Reserve System established under section 315 to improve the understanding, stewardship, and management of coastal and estuarine resources, including the development, application, and transfer to local, State, and Federal resources managers of innovative coastal and estuarine resources management technologies and techniques.''. (b) Definition of Resource Stewardship.--Section 304 of such Act (16 U.S.C. 1453) is amended by adding at the end the following: ``(19) The term `resource stewardship' means the implementation of management, research, and public education and outreach methods and techniques to ensure the long-term conservation of fish, wildlife, and plant resources and the maintenance of biological integrity, diversity, and environmental health of coastal and estuarine resources.''. (c) National Estuarine Reserve System.--Section 315 of such Act (16 U.S.C. 1461) is amended to read as follows: ``national estuarine reserve system ``Sec. 315. (a) Establishment of the System.-- ``(1) In general.--There is established the National Estuarine Reserve System. The System shall consist of-- ``(A) each component of the National Estuarine Research Reserve System established by this section, as in effect immediately before the enactment of the National Estuarine Reserve System Act of 2003; and ``(B) each national estuarine reserve designated under this section. ``(2) Purpose.--The purpose of the System and of each reserve is to improve the understanding, stewardship, and management of coastal and estuarine resources. ``(3) Designation of existing sanctuaries as reserves.-- Each component of the National Estuarine Research Reserve System referred to in paragraph (1)(A) is hereby designated as a national estuarine reserve. ``(b) Designation of National Estuarine Reserves.--The Secretary may designate an area as a national estuarine reserve if-- ``(1) the area-- ``(A) includes any part or all of an estuary and any island, transitional area, and upland in, adjoining, or adjacent to the estuary; and ``(B) constitutes to the extent feasible a natural unit; ``(2) the Government of the coastal State in which the area is located nominates the area for that designation; and ``(3) the Secretary finds that-- ``(A) the area is a representative estuarine ecosystem that is suitable for long-term research and contributes to the biogeographical and typological balance of the System; ``(B) the law of the coastal State provides long- term protection for reserve resources to ensure a stable environment for research, education, and resource stewardship; and ``(C) designation of the area as a reserve will serve to enhance public awareness and understanding of coastal and estuarine resources, and provide suitable opportunities for education, interpretation, training, and demonstration projects to improve management of coastal and estuarine resources. ``(c) Coastal and Estuarine Research, Education, and Resource Stewardship Guidelines.-- ``(1) In general.--The Secretary shall develop guidelines for the conduct of research, education, and resource stewardship within the System that shall include-- ``(A) a mechanism for identifying, and establishing priorities among, the coastal and estuarine management issues that should be addressed through coordinated research, education, and resource stewardship within the System; ``(B) the establishment of common principles and objectives to guide the development of research, education, and resource stewardship programs within the System; ``(C) the identification of uniform research methodologies which will ensure comparability of data, the broadest application of research results, and the maximum use of the System for research purposes; ``(D) the establishment of performance standards upon which the effectiveness of the research, education, and resource stewardship efforts and the value of reserves within the System in addressing the coastal and estuarine management issues identified in subparagraph (A) may be measured; and ``(E) the consideration of sources of funds for coastal and estuarine research, education, and resource stewardship in addition to the funds authorized under this title, and strategies for encouraging the use of such funds within the System, with particular emphasis on mechanisms established under subsection (d). ``(2) Consultation.--In developing the guidelines under this section, the Secretary shall consult with State representatives and prominent members of the coastal and estuarine research, education, and resource stewardship community. ``(d) Promotion and Coordination of Coastal and Estuarine Research, Education, and Resource Stewardship.-- ``(1) In general.--The Secretary shall take such actions as are necessary to promote and coordinate the use of the System for coastal and estuarine research, education, and resource stewardship purposes. ``(2) Required actions.--Actions under this subsection shall include the following: ``(A) Requiring that research, education, and resource stewardship activities administered or supported by the Secretary and relating to coastal and estuarine resources give priority consideration to activities that use the System. ``(B) Consulting with other Federal and State agencies to promote use of one or more reserves within the System by such agencies when conducting coastal and estuarine research, education, and resource stewardship activities. ``(C) Establishing partnerships with other Federal and State coastal and estuarine management programs to coordinate and collaborate on coastal and estuarine research, education, and resource stewardship. ``(e) Financial Assistance.-- ``(1) In general.--The Secretary may, in accordance with such rules and regulations as the Secretary shall promulgate, make grants-- ``(A) to a coastal State-- ``(i) for purposes of acquiring such lands and waters, and any property interests therein, as are necessary to ensure the appropriate long-term management of an area as a reserve and constructing appropriate reserve facilities; ``(ii) for purposes of operating or managing a reserve; or ``(iii) for purposes of conducting resource stewardship, educational, or interpretive activities at a reserve; and ``(B) to any coastal State or public or private person for purposes of-- ``(i) supporting research and monitoring within a reserve that are consistent with the research guidelines developed under subsection (c); or ``(ii) conducting educational, interpretive, or training activities for a reserve that are consistent with the education guidelines developed under subsection (c). ``(2) Terms and conditions.--Financial assistance provided under paragraph (1) shall be subject to such terms and conditions as the Secretary considers necessary or appropriate to protect the interests of the United States, including requiring coastal States to execute suitable title documents setting forth the property interest or interests of the United States in any lands and waters acquired in whole or part with such financial assistance. ``(3) Amount of assistance.--(A) The amount of the financial assistance provided under paragraph (1)(A)(i) with respect to the acquisition of lands and waters, or interests therein, for any one national estuarine reserve may not exceed an amount equal to 50 percent of the costs of the lands, waters, and interests therein. ``(B)(i) Except as provided in clause (ii), the amount of the financial assistance provided under paragraph (1)(A)(ii) and paragraph (1)(B) may not exceed 70 percent of the costs incurred to achieve the purposes described in those paragraphs with respect to a reserve. ``(ii) The amount of financial assistance provided for education and interpretive activities under paragraph (1)(A)(iii) or research and monitoring activities under paragraph (1)(B) may be up to 100 percent of any costs for activities that service the System as a whole, including System-wide monitoring equipment acquisition, data management, and data synthesis; administration and synthesis of System-wide research programs; and graduate research fellowship programs. ``(C) Notwithstanding subparagraphs (A) and (B), financial assistance under this subsection provided from amounts recovered as a result of damage to natural resources located in the coastal zone may be used to pay 100 percent of the costs of activities carried out with the assistance. ``(4) Donations.--(A) The Secretary may-- ``(i) enter into cooperative agreements or contracts with any nonprofit organization established to benefit a reserve, authorizing the organization to solicit donations to carry out projects, other than general administration of the reserve or the System, that are consistent with the purpose of the reserve and the System; and ``(ii) accept donations of funds and services for use in carrying out projects, other than general administration of a reserve or the System, that are consistent with the purpose of the reserve and the System. ``(B) Donations accepted under this paragraph shall be considered as a gift or bequest to or for the use of the United States for carrying out this section. ``(f) Evaluation of System Performance.-- ``(1) In general.--The Secretary shall periodically evaluate the operation and management of each reserve, including coordination with State programs established under section 306, education and interpretive activities, and the research being conducted within the reserve. ``(2) Suspension of financial assistance.--If evaluation under paragraph (1) reveals that the operation and management of the reserve is deficient, or that the research, education, or resource stewardship being conducted within the reserve is not consistent with the guidelines developed under subsection (c), the Secretary may suspend the eligibility of that reserve for financial assistance under subsection (e) until the deficiency or inconsistency is remedied. ``(3) Withdrawal of designation.--The Secretary may withdraw the designation of an estuarine area as a reserve if evaluation under paragraph (1) reveals that-- ``(A) the basis for any one or more of the findings made under subsection (b)(3) regarding that area no longer exists; ``(B) a substantial portion of the research, education, or resource stewardship conducted within the area, over a period of years, has not been consistent with the guidelines developed under subsection (c); or ``(C) the coastal State in which the area is located has not complied with the requirements of any guidelines developed under subsection (c). ``(g) Report.--Every 2 years the Secretary shall report to the Committee on Resources of the House of Representatives and the Committee on Commerce, Science, and Transportation of the Senate information regarding-- ``(1) the designation of new reserves; ``(2) the expansion of existing reserves; ``(3) the status of the research, education, and resource stewardship program being conducted within the System; and ``(4) a summary of the evaluations made under subsection (f). ``(h) Definitions.--In this section: ``(1) Reserve.--The term `reserve' means a component of the National Estuarine Reserve designated under subsection (a)(3) or (b). ``(2) System.--The term `System' means the National Estuarine Reserve System established by this section.''. (d) Authorization of Appropriations.--Section 318 of such Act (16 U.S.C. 1464) is amended-- (1) in subsection (a) by striking paragraph (2) and inserting the following: ``(2) for grants under section 315-- ``(A) $35,000,000 for fiscal year 2004; ``(B) $36,000,000 for fiscal year 2005; ``(C) $37,000,000 for fiscal year 2006; ``(D) $38,000,000 for fiscal year 2007; and ``(E) $39,000,000 for fiscal year 2008''; and (2) by adding at the end thereof the following: ``(d) Limitation on Grants for Acquisition and Construction for Reserves.--The Secretary shall ensure that of the funds provided under paragraph (2) of subsection (a), no more than $15,000,000 is used for assistance under section 315(e)(1)(A)(i).''.

National Estuarine Reserve System Act of 2003 - Amends the Coastal Zone Management Act of 1972 to rename the National Estuarine Research Reserve System the National Estuarine Reserve System, and designates existing sanctuaries as part of the System.Authorizes the Secretary of Commerce to designate additional areas as part of the System and specifies requirements for such.Authorizes the Secretary to: (1) contract with an organization to solicit donations to carry out projects; and (2) accept such donations of funds and services.

Researchers in Aalto University have developed a new concept for computing, using water droplets as bits of digital information. This was enabled by the discovery that upon collision with each other on a highly water-repellent surface, two water droplets rebound like billiard balls. In the work, published in the journal Advanced Materials, the researchers experimentally determined the conditions for rebounding of water droplets moving on superhydrophobic surfaces. In the study, a copper surface coated with silver and chemically modified with a fluorinated compound was used. This method enables the surface to be so water-repellent that water droplets roll off when the surface is tilted slightly. Superhydrophobic tracks, developed during a previous study, were employed for guiding droplets along designed paths. Using the tracks, the researchers demonstrated that water droplets could be turned into technology, "superhydrophobic droplet logic." For example, a memory device was built where water droplets act as bits of digital information. Furthermore, devices for elementary Boolean logic operations were demonstrated. These simple devices are building blocks for computing. Video: http://youtu.be/GTnVwyWaVQw (Superhydrophobic droplet logic: flip-flop memory) Furthermore, when the water droplets are loaded with reactive chemical cargo, the onset of a chemical reaction could be controlled by droplet collisions. Combination of the collision-controlled chemical reactions with droplet logic operations potentially enables programmable chemical reactions where single droplets serve simultaneously as miniature reactors and bits for computing. Video: http://youtu.be/ygMdQ9NUbok (Chemical reaction controlled by droplet collisions) "It is fascinating to observe a new physical phenomenon for such everyday objects -- water droplets," says Robin Ras, an Academy Research Fellow in the Molecular Materials research group. "I was surprised that such rebounding collisions between two droplets were never reported before, as it indeed is an easily accessible phenomenon: I conducted some of the early experiments on water-repellent plant leaves from my mother's garden," explains a member of the research group, Henrikki Mertaniemi, who discovered the rebounding droplet collisions two years ago during a summer student project in the research group of Ras and Academy Professor Olli Ikkala. The researchers foresee that the present results enable technology based on superhydrophobic droplet logic. Possible applications include autonomous simple logic devices not requiring electricity, and programmable biochemical analysis devices. Other related videos are available on YouTube: http://www.youtube.com/playlist?list=PLstvxmQiQw29IYEmSVYPdRvG2efzR-jku ||||| Researchers at Aalto University have devised a way to convert tiny drops of water into encoded digital information, building a simple computer out of just water droplets and a water-repellant surface. A new study in the journal Advanced Materials demonstrates that, using a hydrophobic surface that causes water to bead up and roll off, researchers can follow the trails of individual water droplets along paths in the surface. That predictability allowed researchers to build simple computers like a memory device that tracks the droplets and encodes them as bits of information, with drops on one track representing ones and drops on the other representing zeroes. They even demonstrated machines that can use the technology to complete basic Boolean operations. The new technology is known as “superhydrophobic droplet logic,” (which means that Beck will have to think of a new name for his next album) and it doesn’t stop at just encoding information. By creating water droplets that carry chemical cargos and controlling where they went, the research team could even program chemical reactions. The research released today is just a proof of concept for now, and it will be years before the technique sees any practical applications — if it ever does. It’s an interesting and heretofore unheard of concept, though, and one that if developed further could lead to simple logic devices that can run without any electrical power. The programmable chemical reactions hold even more promise, with the potential to see use in simple chemical analysis systems that could sniff out pollution or diagnose disease. For right now, you can take a look at the video below to see the new technique in action. (via ScienceDaily, image courtesy of Aalto University) Relevant to your interests

– Could the future of computers be water? Researchers in Finland may have laid the groundwork by converting water droplets into digital data. The concept came out of a discovery that water droplets on a water-repellent surface ricochet off each other like billiard balls, reports Science Daily. Scientists added tracks and were able to predict the paths of the droplets, and from this they were able to create Boolean logic operations, the foundation of computing. In an experiment, the scientists used a silver-coated copper surface to build a memory device in which water droplets acted as the bits of information. The technology has been named superhydrophobic droplet logic. Geekosystem's take: "The research released today is just a proof of concept for now, and it will be years before the technique sees any practical applications—if it ever does. It’s an interesting and heretofore unheard of concept, though, and one that if developed further could lead to simple logic devices that can run without any electrical power."

New numbers actually show a decline over the past 30 years. America's infertility rate is not rising, according to new government data. (Photo: Getty Images/Comstock Images) Story Highlights Data fly in the face of popular wisdom about infertility More talk about infertility may make it seem like it's on the rise, researcher says Women over age 35 may not wait a year to seek medical treatment Are fertility problems the inevitable fallout of the USA's older marriage ages? No, suggest new federal data released Wednesday that show infertility has actually declined. "When you look at this downward trend, it goes against the popular wisdom of people we all know," says the report's lead author, Anjani Chandra, a health scientist at the National Center for Health Statistics. Data show the percentage of married women ages 15-44 who were infertile fell from 8.5% in 1982 to 6% from 2006 to 2010. The actual numbers represent a drop from 2.4 million women to 1.5 million. For unmarried women living with a male partner, the new data show 4.9% as infertile. Today's median age at first marriage is the highest ever: 26.6 for women and 28.6 for men, according to 2012 data from the U.S. Census. Infertility, according to the agency's definition, is "lack of pregnancy in the 12 months prior to the survey, despite having had unprotected sexual intercourse in each of those months with the same husband or partner." "People seem to think it's going up, when the fact is that it's remarkably stable, despite the preponderance of medical services," Chandra says. "The level of infertility is being counteracted by their pursuit of medical help to have a child. Both together are bringing down the percentage we see as infertile when we do our survey." The report is based on 22,682 face-to-face interviews, including 12,279 women and 10,403 men. STORY: Jimmy Fallon: 'We had a surrogate' Another measure called "impaired fecundity" is "physical difficulty in either getting pregnant or carrying a pregnancy to live birth." For married women of those ages, impaired fecundity was 12% in the latest data. Physician Richard Reindollar, president-elect of the American Society for Reproductive Medicine, says his organization finds the new data encouraging. "Even though the ages at which women in the United States have their children have been increasing since 1995, the percentage of the population suffering from infertility or impaired fecundity has not increased," says Reindollar, of Dartmouth College in Hanover, N.H. Rafat Abbasi, a reproductive endocrinology physician in Bethesda, Md., says the time period in which the survey was conducted may well play a role in the data's recent stability. "People were getting older — beyond the scope of fertility treatments," she says. "And the second thing is the economic recession, when a lot of people couldn't afford to do these treatments. I don't think it was due to more fertile people being around. It's more a factor of these coexisting conditions." Both Abbasi and Chandra say the definition of infertility may affect the data. Chandra speculates that some — such as a woman over 35 — may not wait 12 months for medical intervention, which means she wouldn't meet the report's definition for being infertile. However, Barbara Collura, executive director of RESOLVE: The National Infertility Association, a non-profit based in McLean, Va., says she doesn't think people are seeking help sooner. "I'm very frustrated that people wait too long to see a specialist. I hear it anecdotally over and over." Chandra says the single most important factor associated with fertility problems is the age at which a woman tries to have her first child. The drop from 44% to 27% for infertility from 1982 to 2006-10 for women ages 35-44 is due to both the likelihood of medical treatment as well as the smaller pool of people trying to become pregnant at those ages, she says. Collura says it's unclear what to make of the new federal data. "We have more people seeking our services and being part of our community than ever before," she says. "Does that mean there are more people with infertility? Not necessarily." A barrier to treatment is cost, she says, citing an online survey her organization conducted last month of 1,694 individuals. The not-yet-released data show that 60% of respondents have little to no insurance coverage for infertility treatment. In addition to testing, which can cost up to $1,500, infertility treatments can cost $13,000 to $15,000 per treatment, Abbasi says. Despite a boom in the use of pregnancy-aiding medical techniques, a new government study suggests the percentage of married couples having trouble conceiving has actually dropped slightly in recent years. (Photo: LM Otero, AP) Read or Share this story: http://usat.ly/169dr3o ||||| Infertility rates decreased significantly among US women between 1982 and 2010, according to the findings of the National Survey of Family Growth (NSFG).The results continue a downward national trend for female infertility or impaired fecundity from a high of 11.2% of married women aged 15 to 44 years in 1965 to 6% between 2006 and 2010. Anjani Chandra, PhD, from the National Center for Health Statistics, Hyattsville, Maryland, and colleagues present their findings in a report published online August 14 in National Health Statistics Reports. In the study, the researchers used data from the NSFG, which was conducted from June 2006 to June 2010, to assess rates of infertility and impaired fecundity in US adults. They compared those data with past NSFG data. The surveys indicate that the percentage of married women between 15 and 44 years of age who were infertile, defined as an inability to become pregnant for at least 12 months despite having unprotected sex with the same husband or partner in each of those months, declined from 8.5% in 1982 to 6.0% in 2010. Conversely, impaired fecundity, defined as physical difficulty in becoming pregnant or carrying a pregnancy to live birth, increased from 10.8% in 1982 to 12.9% in 1995, and peaking at 15.1% in 2002 before falling to 12.1% in 2006-2010. Age appears to be a factor in infertility for women. The investigators found that 7.0% of women between 15 and 24 years of age had impaired fecundity compared with 13% of women aged 25 to 44 years. Among nulliparous women, 14% of the women aged 25 to 29 years were infertile or subfertile, whereas 30% of those aged 40 to 44 years were. Infertility did not appear to be associated with education or income level, although a higher education level and greater income appeared to be linked with lower levels of surgical infertility. (Presumed fecund included those individuals who did not fit into the subfertile, surgically sterile, or nonsurgically sterile groups.) In addition, 63.9% of women with at least a Master's degree were presumed fecund compared with 35.3% of women with no high school diploma or equivalent. A greater percentage of Asian women (74.6%) were presumed to be fertile compared with other ethnicities (49.1% - 52.6%). In multivariate analysis adjusted for demographic variables such as income and education, an age of 40 to 44 years among nulliparous women was significantly associated with both impaired fecundity (odds ratio [OR], 3.48; 95% confidence interval [CI], 2.26 - 5.36) and 12-month infertility (OR, 12.61; 95% CI, 6.19 - 25.71) compared with parous women age of 22 to 29 years. Regarding fertility intentions, 59% of nulliparous women with impaired fecundity intended to have children compared with 39% of parous women. In addition, 64% of married nulliparous women with 12-month infertility planned to conceive vs 53% of parous, married infertile women. Among men aged 15 to 44 years, fertility rates were similar between 2002 (73.8%) and 2006-2010 (76.7%). However, infertility, particularly surgical sterilization, was more common among men aged 40 to 44 years than among their younger counterparts. The authors have disclosed no relevant financial relationships. National Health Stat Rep. Published online August 14, 2013. Full text

– Good news for women planning to have a baby later in life: Infertility is actually on the decline, even as average marriage ages climb. A new report shows that of married women, aged 15 to 44, just 6% are infertile, down 2.5% since 1982. For women 35 to 44, the number is quite a bit higher at 27%, but that still marks a drastic change from 44% in 1982, Medscape reports. So what's behind the downward trend? Fertility treatment and fewer women trying to get pregnant later, researchers say. "The level of infertility is being counteracted by their pursuit of medical help to have a child," the study lead told USA Today. "Both together are bringing down the percentage we see as infertile when we do our survey." But while infertility may be headed downward, the report, which interviewed 22,682 men and women, noted the number of those who have difficulty getting pregnant or carrying a pregnancy to term rose almost 5% from 10.8% to 15% in 2002—though the newest data shows it settled at about 12%.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Major Drug Trafficking Prosecution Act of 2009''. SEC. 2. FINDINGS. Congress makes the following findings: (1) Since the enactment of mandatory minimum sentencing for drug users, the Federal Bureau of Prisons budget increased from $220 million in 1986 to $5.4 billion in 2008. (2) Mandatory minimum sentences are statutorily prescribed terms of imprisonment that automatically attach upon conviction of certain criminal conduct, usually pertaining to drug or firearm offenses. Absent very narrow criteria for relief, a sentencing judge is powerless to mandate a term of imprisonment below the mandatory minimum. Mandatory minimum sentences for drug offenses rely solely upon the weight of the substance as a proxy for the degree of involvement of a defendant's role. (3) Mandatory minimum sentences have consistently been shown to have a disproportionate impact on African Americans. The United States Sentencing Commission, in a 15-year overview of the Federal sentencing system, concluded that ``mandatory penalty statutes are used inconsistently'' and disproportionately affect African American defendants. As a result, African American drug defendants are 20 percent more likely to be sentenced to prison than white drug defendants. (4) In the Anti-Drug Abuse Act of 1986, Congress structured antidrug penalties to encourage the Department of Justice to concentrate its enforcement effort against high-level and major-level drug traffickers, and provided new, long mandatory minimum sentences for such offenders, correctly recognizing the Federal role in the combined Federal-State drug enforcement effort. (5) Between 1994 and 2003, the average time served by African Americans for a drug offense increased by 62 percent, compared with a 17 percent increase among white drug defendants. Much of this disparity is attributable to the severe penalties associated with crack cocaine. (6) African Americans, on average, now serve almost as much time in Federal prison for a drug offense (58.7 months) as whites do for a violent offense (61.7 months). (7) Linking drug quantity with punishment severity has had a particularly profound impact on women, who are more likely to play peripheral roles in a drug enterprise than men. However, because prosecutors can attach drug quantities to an individual regardless of the level of culpability of a defendant's participation in the charged offense, women have been exposed to increasingly punitive sentences to incarceration. (8) In 2003, the States sentenced more than 340,000 drug offenders to felony convictions, compared to 25,000 Federal felony drug convictions. (9) Low-level and mid-level drug offenders can be adequately prosecuted by the States and punished or supervised in treatment as appropriate. (10) Federal drug enforcement resources are not being properly focused, as only 12.8 percent of powder cocaine prosecutions and 8.4 percent of crack cocaine prosecutions were brought against high-level traffickers, according to the Report to Congress: Cocaine and Federal Sentencing Policy, issued May, 2007 by the United States Sentencing Commission. (11) According to the Report to Congress, ``The majority of federal cocaine offenders generally perform low-level functions . . .''. (12) The Departments of Justice, Treasury, and Homeland Security are the agencies with the greatest capacity to investigate, prosecute and dismantle the highest level of drug trafficking organizations, and investigations and prosecutions of low-level offenders divert Federal personnel and resources from the prosecution of the highest-level traffickers, for which such agencies are best suited. (13) Congress must have the most current information on the number of prosecutions of high-level and low-level drug offenders in order to properly reauthorize Federal drug enforcement programs. (14) One consequence of the improper focus of Federal cocaine prosecutions has been that the overwhelming majority of low-level offenders subject to the heightened crack cocaine penalties are black and according to the Report to Congress only 8.8 percent of Federal crack cocaine convictions were imposed on whites, while 81.8 percent and 8.4 percent were imposed on blacks and Hispanics, respectively (15) According to the 2002 Report to Congress: Cocaine and Federal Sentencing Policy, issued May, 2002 by the United States Sentencing Commission, there is ``a widely-held perception that the current penalty structure for federal cocaine offenses promotes unwarranted disparity based on race''. (16) African Americans comprise 12 percent of the US population and 14 percent of drug users, but 30 percent of all Federal drug convictions. (17) Drug offenders released from prison in 1986 who had been sentenced before the adoption of mandatory sentences and sentencing guidelines had served an average of 22 months in prison. Offenders sentenced in 2004, after the adoption of mandatory sentences, were expected to serve almost three times that length, or 62 months in prison. (18) According to the Justice Department, the time spent in prison does not affect recidivism rates. (19) Government surveys document that drug use is fairly consistent across racial and ethnic groups. While there is less data available regarding drug sellers, research finds that drug users generally buy drugs from someone of their own racial or ethnic background. But almost three-quarters of all Federal narcotics cases are filed against blacks and Hispanics, many of whom are low-level offenders. SEC. 3. APPROVAL OF CERTAIN PROSECUTIONS BY ATTORNEY GENERAL. A Federal prosecution for an offense under the Controlled Substances Act, the Controlled Substances Import and Export Act, or for any conspiracy to commit such an offense, where the offense involves the illegal distribution or possession of a controlled substance in an amount less than that amount specified as a minimum for an offense under section 401(b)(1)(A) of the Controlled Substances Act (21 U.S.C. 841(b)(1)(A)) or, in the case of any substance containing cocaine or cocaine base, in an amount less than 500 grams, shall not be commenced without the prior written approval of the Attorney General. SEC. 4. MODIFICATION OF CERTAIN SENTENCING PROVISIONS. (a) Section 404.--Section 404(a) of the Controlled Substances Act (21 U.S.C. 844(a)) is amended-- (1) by striking ``not less than 15 days but''; (2) by striking ``not less than 90 days but''; (3) by striking ``not less than 5 years and''; and (4) by striking the sentence beginning ``The imposition or execution of a minimum sentence''. 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this work was supported by the deutsche forschungsgemeinschaft through research unit 945 . computing time at the leibniz computing center in garching is gratefully acknowledged . we thank martin hck for fruitful discussions .

the characterization and manipulation of deposited magnetic clusters or molecules on surfaces is a prerequisite for future utilization . for this purpose spin - flip inelastic electron tunneling spectroscopy using a scanning tunneling microscope proved to be very precise in determining e.g. exchange constants in deposited finite spin chains in the mev range . in this letter we provide numerical justification for the underlying assumptions made in such investigations . to this end we study the impurity magnetization of antiferromagnetic chains for varying couplings to a conduction electron band of a metal substrate . we show under which circumstances the screening of a part of the system enables one to deduce molecular parameters of the remainder from level crossings in an applied field . _ introduction_the question whether and how deposited magnetic clusters or molecules change their magnetic properties when deposited on a metallic substrate is of fundamental importance especially in view of possible applications as next generation storage devices or magnetic logic circuits @xcite . one experimental method to investigate local magnetic properties is spin - flip inelastic electron tunneling spectroscopy with a scanning tunneling microscope @xcite . in this method jumps of the differential conductivity signal transitions between magnetic levels of the deposited entity , of course under the assumption of a weak coupling to the substrate . following this philosophy the authors of ref . @xcite conjectured the strength of superexchange interactions in deposited molecular nanomagnets . the latter were constructed by depositing layers of cobalt phthalocyanine molecules which self - organized in a stacked manner so that the cobalt ions formed finite spin chains on the substrate . this arrangement is scetched in fig . [ molsurf - f - a ] ( a ) . , the lowest moment is coupled to the metal surface with strength @xmath0 . @xmath1 and @xmath0 are unknown , @xmath1 shall be derived from experimental data . ( b ) shows a triangular configuration discussed later in this letter.,width=207 ] when interpreting the observed structure of magnetic levels in such measurements one has to conjecture whether and how much of the deposited magnetic moment is screened by the conduction electrons , since this has a great influence on the magnetic properties of the remainder . in ref . @xcite it was deduced that the co@xmath2 spin with @xmath3 closest to the surface was completely kondo - screened and therefore the observed magnetic levels should result from a practically uncoupled remainder of @xmath4 spins . in this letter we investigate by means of the numerical renormalization group method ( nrg ) @xcite numerically exactly how the magnetic properties of deposited structures as those shown in fig . [ molsurf - f - a ] depend on the exchange coupling @xmath0 to the substrate s conduction electrons , the internal exchange coupling @xmath1 , and the applied magnetic field @xmath5 at low temperature @xmath6 . depending on @xmath0 the screening can vary between full screening and partial screening of the spin-1/2 closest to the surface . in the case of full screening the magnetic properties of the deposited entity are indeed identical to those of the remaining spin system without the screened spin . for our investigations we employ a single - channel single - impurity kondo model as a minimal model to describe the correlations induced by the exchange interaction between the conduction electrons of the non - magnetic metal and one spin of the magnetic molecule @xcite . as already demonstrated in ref . @xcite the magnetization steps due to ground state level crossings in an applied magnetic field can be used as fingerprints of the underlying spin model . this will be shown by investigating different sizes of chains as well as triangular arrangements of magnetic moments . _ reminder on nrg_in order to model a molecule and its coupling to a surface we use the following hamiltonian which consists of three parts @xcite : @xmath7 the first part @xmath8 represents non - interacting electrons on a lattice . the hopping parameter @xmath9 is non - zero only if the lattice sites @xmath10 , @xmath11 are nearest neighbours . @xmath12 and @xmath13 are fermionic creation and annihilation operators for electrons with spin direction @xmath14 . the interaction with an external magnetic field @xmath5 is given by the zeeman term with @xmath15 representing the effective electron spin at lattice site @xmath10 , @xmath16 the g - factor and @xmath17 the bohr magneton . the second part @xmath18 models the impurity , i.e. , the molecule or chain via an effective heisenberg model for all connected spins @xmath19 and a zeeman term . @xmath20 is the interaction between spins @xmath10 and @xmath11 and antiferromagnetic for @xmath21 , @xmath22 the last part @xmath23 describes the kondo - like interaction of the molecule with the surface . the coupling constant @xmath0 is positive for antiferromagnetic coupling @xmath24 to calculate thermodynamic values within this modell we use wilson s numerical renormalization group ( nrg ) with the discretization scheme proposed by itko and pruschke @xcite and a @xmath25-averaging for 2 values . a constant density of states is assumed . it is possible that in reality molecular orbitals of phthalocyanine molecules hybridize with surface states , compare e.g. @xcite . our approach , like others @xcite , simplifies the situation to a point where the deposited molecule is reduced to its spin degrees of freedom which interact with the metal s conduction electrons . _ results and interpretation_before we discuss our numerical results of a finite spin chain interacting with a metal substrate we would like to shortly look at a free three - site chain of spins @xmath3 . its levels split under the influence of an applied magnetic field as depicted on the l.h.s . of fig . [ molsurf - f - c ] . at a certain magnetic field value @xmath26 the lowest @xmath27 and @xmath28 levels cross . if the lowest spin of the trimer would be completely screened , the remaining dimer would possess a different level scheme with a different crossing field @xmath29 as depicted on the r.h.s . of fig . [ molsurf - f - c ] . therefore , infering @xmath1 from spectroscopic data or equivalently from crossing fields strongly depends on the degree of screening . ( l.h.s . ) and of a dimer of two spins @xmath3 ( r.h.s.).,title="fig:",width=151 ] ( l.h.s . ) and of a dimer of two spins @xmath3 ( r.h.s.).,title="fig:",width=151 ] in the following we discuss the so - called impurity magnetization , i.e. the thermal expectation value of molecular magnetic moment @xmath30 as a function of the applied field for various couplings to the substrate . in order to work with reasonable numbers we set the intramolecular coupling to @xmath31 mev and the half - bandwidth of the metal to @xmath32 ev . as the temperature we choose @xmath33 k , which is lower than the intramolecular coupling , but not too low so that thermodynamic functions are still smooth . after looking at the lowest zeeman levels of a free trimer we now consider the coupling of such a trimer to a surface as described by eq . ( [ e-2 - 4 ] ) and shown in fig . [ molsurf - f - a ] ( a ) . the strength of the coupling is parametrized by @xmath0 . the impurity magnetization curves depicted in fig . [ trimer ] cover the whole range from the free ( @xmath34 ) or weakly coupled case to the strongly coupled case , which is reached for @xmath35 ev . while the case @xmath0 = 0 coincides with the discussed free trimer by construction , the strongly coupled case coincides with the magnetization curve of a free dimer . ( a ) ; vertical lines mark the crossing fields for various scenarios ; @xmath36 k.,width=321 ] additionally to the magnetization curves , fig . [ trimer ] includes the crossing fields for various scenarios which can be derived from the magnetization curves . the vertical lines marking these fields shift from the analytical solution of a free trimer towards the analytical solution of a free dimer for increasing coupling to the substrate . the analytical solutions thus are boundaries for the crossing field independent of the coupling @xmath0 . focusing on the strong coupling regime , fig . [ trimer15 ] shows variations of the couplings @xmath1 and @xmath0 . within this regime , i.e. for strong enough @xmath0 , the magnetization curves are independent of @xmath0 and coincide with the solution for a free dimer and thus depend on the coupling @xmath1 in the same way the analytical solution does . in particular the crossing field is given by @xmath37 . given a strong enough coupling to reach the strong coupling regime it is therefore possible to derive @xmath1 from the crossing field . our investigation also shows that the maximum uncertainty in the determination of @xmath1 , in the case of unknown @xmath0 , is given by the difference between the ( analytical ) solutions for the crossing field of the unscreened system and the fully screened one . k. the magnetization curve depends only on @xmath1 , not on @xmath0 in the strong coupling case.,width=321 ] similiar results are obtained if a triangular structure is used , where all three spins couple to each other , but still only one couples to the substrate , compare fig . [ molsurf - f - a ] ( b ) . for the case of @xmath34 analytical results can be obtained for both trimer chain and triangle @xcite . these show that the magnetization curves and thus the crossing fields coincide for t @xmath38 0 . figure [ trimertriangle ] shows the magnetization curves of triangle and trimer chain for finite temperature where the curves for @xmath34 feature small differences . for intermediate couplings to the substrate , @xmath39 ev , the differences are more pronounced . k.,width=321 ] figure [ trimertriangle ] furthermore shows the case of strong coupling to the substrate , again @xmath35 ev . in this case trimer chain and triangle are indistinguishable on the basis of their magnetization curves and thus their crossing fields , compare @xmath40-symbols and upright triangles in fig . [ trimertriangle ] . after considering the triangle , and thus a slightly different structure of the impurity , we now come back to chain - like impurities and extend our original trimer chain to four and five spins analogous to the experiment in ref . @xcite . figure [ tetramer ] shows the magnetization curves of a tetramer chain for various couplings to the substrate . k.,width=321 ] the curves are affected by the coupling to the substrate in a similar way to those of the trimer chain with the crossing fields decreasing for stronger couplings . in the strong coupling regime the tetramer chain then shows the same magnetization curve and crossing field as the free trimer . analogously the magnetization curve and crossing fields of the pentamer chain , as depicted in fig . [ pentamer ] , coincide with those of the free tetramer in the strong coupling limit . k.,width=321 ] unlike the other figures , figures [ tetramer ] and [ pentamer ] include vertical lines which confine areas of ( practically ) constant magnetization for the free and the strongly coupled chains at a now very low temperature of @xmath41 k. for those areas an arrow indicates whether the magnetization is increased ( green arrow ) or decreased ( red arrow ) due to the coupling to the substrate . for the tetramer chain with its ground state spin of @xmath42 the screening leads to an increased magnetization at ( and thus a responce to ) small magnetic fields . in contrast the magnetization for the pentamer chain with its ground state spin of @xmath43 is decreased at small magnetic fields and thus will not respond to small magnetic fields in the strong coupling regime . summarizing , nrg calculations of the impurity magnetization provide a very valuable tool in order to rationalize experimental assumptions and results as for instance those of ref . @xcite . future investigations of more complicated impurities as for instance magnetic molecules with non - heisenberg terms in the hamiltonian pose no problem , but nrg is technically limited to single - channel ( or with massive super computing time to two - channel ) contacts . this is due to the rapidly growing hilbert space dimension which is already for two channels the square of the dimension for one channel .

the development of heavy quark theory started in the 1980 s , has essentially been completed . while at the early stages the main emphasis was placed on the symmetry aspects ( the so - called heavy quark symmetry ) , the present ( mature ) stage deals with dynamical aspects . a formalism based on wilson s operator product expansion ( ope ) @xcite has been developed and applied to many cases of practical interest , in particular to inclusive decays of heavy flavor hadrons . the theory of such decays is at a rather advanced stage now ( see @xcite and references therein ) . calculations we could not even dream of several years ago have become possible . the decays of heavy flavor hadrons @xmath2 are shaped by nonperturbative dynamics . while qcd at large distances is not yet solved , considerable progress has been achieved in this problem . the width of an inclusive transition @xmath3 is expressed through an ope . the nonperturbative effects are then parameterized through expectation values of various local operators @xmath4 built from the quark and/or gluon fields . observable quantities , such as semileptonic and nonleptonic widths of heavy hadrons @xmath2 , are then given by @xmath5 where @xmath6 are the ope coefficients , and @xmath7 stands for a normalization point separating out soft contributions ( which are lumped into the matrix elements @xmath8 ) from the hard ones ( which belong to the coefficient functions @xmath6 ) . there are many subtle and interrelated issues , both conceptual and technical , associated with the operator product expansion in qcd : 1 . ( [ gamma ] ) represents an expansion in powers of @xmath1 with @xmath9 being the @xmath10 quark mass and the coefficients @xmath6 scaling like @xmath11 for an operator with dimension @xmath12 . in @xmath13 there are two sources for contributions depending on powers of @xmath1 , namely higher - dimensional _ operators _ and higher - order terms in the expansion of their _ expectation values_. in addition every coefficient @xmath14 is a series in the running coupling @xmath15 , of which only a few terms are known for a given coefficient @xmath6 . this immediately raises a grave concern : how can we retain terms suppressed by powers of @xmath1 without a complete summation of the parametrically larger powers of @xmath16 in the leading coefficient ? 2 . although the normalization point @xmath7 conceptually represents a straightforward book - keeping " device for separating hard and soft contributions , it is technically difficult to actually carry out such a program since no user - friendly definition of what is soft and hard exists in qcd . so far , the vast majority of all discussions related to the introduction of @xmath7 are conducted in a hand - waving manner . it is quite conceivable that there are _ hard _ _ non_perturbative contributions in the coefficient functions : @xmath17 with @xmath18 being some positive number . the possible size of such contributions is essentially unknown . a related problem is the convergence ( or divergence ) of the perturbative series for the coefficient functions @xmath6 . 4 . truncating the series ( [ gamma ] ) at some finite order introduces an error estimated by so - called exponential terms , which in euclidean domain look as expressions of the type @xmath19 $ ] . in order to obtain @xmath13 we analytically continue from the euclidean domain , where the ope is well defined and the coefficients @xmath6 are real , to the minkowski domain where they acquire an imaginary part . such analytic continuation is implicit in eq . ( [ gamma ] ) and is based on the assumption of smoothness . under analytic continuation the exponential terms convert themselves into _ oscillating _ terms of the type @xmath20 $ ] @xcite ; the expansion ( [ gamma ] ) does not account for them . it can thus be understood on general grounds that duality violation is described or at least modeled by oscillating expressions . to which degree those are suppressed by powers of @xmath1 depends on details of the strong interactions and the specifics of the process . all these questions are circumvented in the so - called _ practical version _ of ope @xcite routinely used so far in all instances when there is need in numerical predictions . this version is admittedly approximate , however . the questions formulated above are legitimate ; they deserve to attract theorists attention , and continue to cause confusion in the literature . they have to be addressed also because they are emerging as a major source of the uncertainties in quantitative predictions ; these problems have specifically been suspected to underlie phenomenological difficulties encountered recently , e.g. a relatively short lifetime of beauty baryons and a relatively small semileptonic branching ratio of beauty mesons . we find it useful and instructive to study all these issues in models that while retaining basic features of qcd most notably quark confinement are simpler without being trivial and can be solved dynamically . qcd defined in one time and one space dimension hereafter referred to as 1 + 1 qcd is especially suitable for this purpose : with the coulomb potential necessarily growing linearly in two dimensions , quark confinement is built in . likewise the theory is superrenormalizable , i.e. very simple in the ultraviolet domain . there are no logarithmically divergent tails " in the feynman graphs . as a result , the book - keeping of ope ( separation of the hard and soft parts ) becomes simple , and all subtle aspects in the construction of the ope can be studied in a transparent environment . in particular , the perturbative contributions in the coefficients @xmath6 become an expansion in @xmath21 ( where @xmath22 is the gauge coupling in 1 + 1 qcd ) . they are thus power - suppressed in the same way as the higher - dimensional operators ; the first problem formulated above therefore does not arise here . without the logarithmic uv tails the second problem becomes tractable . concerning the third problem it is easy to see that in 1 + 1 qcd nonperturbative corrections can not generate power suppressed terms in the coefficients @xmath6 . for the leading operator @xmath23 we will find its coefficient function to all orders of perturbation theory ( in the limit of @xmath24 ) , demonstrating the convergence of the perturbative series . at the same time , the divergence of the condensate expansion in high orders will become manifest indirectly , through the occurrence of oscillating terms in @xmath13 , which appear with suppression factor @xmath25 in the case at hand . thus _ all the four _ problems formulated above will be answered ! we will perform our explicit calculations for 1 + 1 qcd in the limit of a large number of colors @xmath26 the famous t hooft model @xcite . for @xmath24 only planar diagrams contribute in qcd ; 1 + 1 qcd has the additional special feature that one can choose a gauge such that there are no gluon self - interactions . then only planar ladder diagrams have to be considered , and we have an exactly solvable theory in our hands . all hadronic matrix elements of interest are therefore calculable . this enables us to describe every given transition in two complementary ways : we can confront the ope - based expression with a phenomenological " representation for the same process obtained by saturating the rate by exclusive hadronic channels . we want to take advantage of these unique features of the t hooft model to illustrate all crucial elements of heavy quark theory and the theory of inclusive heavy flavor decays in particular . one should keep in mind that heavy quark theory , as we know it now , is merely an adaptation of the general ope - based approach . some of the questions to be discussed below can therefore be actually formulated in a wider setting . the t hooft model has been exploited as a theoretical laboratory for testing various analytic qcd methods in applied problems before . heavy quark symmetry and heavy flavor decays were analyzed in refs . the model was used recently for discussing general aspects of ope ( convergence of the ope series , exponential terms violating duality , and so on ) @xcite . in ref . @xcite heavy flavor inclusive widths were calculated numerically , by adding the exclusive channels one by one . it was found that the inclusive width @xmath13 approaches its asymptotic ( partonic ) value , and the sum over the exclusive hadronic states converges rapidly . at the same time , small deviations from the asymptotic value observed in the numerical analysis @xcite were claimed to be a signal of @xmath1 corrections in the total width , in contradiction with the ope - based result . in this work we treat the very same problem , inclusive heavy flavor decays in 1 + 1 qcd , _ analytically_. we first develop a technique perfectly parallel to that in four - dimensional qcd @xcite . it includes such elements as a complete operator analysis and the construction of the transition operator . unlike four - dimensional qcd , the coefficient functions for the leading operator are exactly calculable ( in the limit @xmath27 ) . moreover , all relevant expectation values of the local operators involved in the problem are calculable too . we get a complete prediction through order @xmath28 . then we carry out a hadronic calculation " of the same width , by saturating all open decay modes , using the t hooft equation @xcite . by comparing the phenomenological representation of the total width with the ope - based formula , we are able to identify , term - by - term , the subsequent terms of the heavy quark expansion . the situation actually turns out to be simpler than one could expect _ a priori _ : * in the @xmath1 expansion for the inclusive width corrections of the order @xmath29 , @xmath30 and @xmath31 to the parton width come only from the leading operator @xmath32 , i.e. , from the expansions of its ope coefficient @xmath33 and its expectation value @xmath34 . operators of higher dimension contribute to the total width first at order @xmath35 . * the perturbative series in @xmath21 for the ope coefficient of the operator @xmath32 is completely defined by the one - loop renormalization of heavy quark mass . the result can be formulated in terms of the light - cone gauge formalism as the absence of renormalization . these results are based on a general operator analysis . on the phenomenological " side , we use a sum rule , which is a consequence of the t hooft equation , to show that the total width is determined by a quantity coinciding with the matrix element of the @xmath36 term in the ope expansion ( [ gamma ] ) , through order @xmath31 . thus , we observe a _ perfect match _ between the expression derived from the ope and from adding up all relevant hadronic channels up to high order power corrections . after testing the validity of ope , we exploit results obtained _ en route _ in order to discuss the issue of oscillating contributions related to the high - order tails in the ope series that are factorially divergent . due to the simplicity of the model we can estimate them reliably . a non - monotonous duality - violating component of the width for large @xmath9 is suppressed by high power of @xmath1 which we determined . implications of our analysis for real qcd are briefly discussed . the remainder of the paper is organized as follows : after formulating the problem in sec . [ sec : preliminaries ] we construct the ope and calculate the coefficients in sec . [ sec : ope ] ; after establishing the match between the ope - based result for the inclusive width and the sum rules for the same width resulting from the t hooft equation through order @xmath31 in sec . [ sec : match ] , we discuss an appearance of oscillating terms in the order @xmath25 and the duality violations they cause in sec . [ sec : violations ] ; in the same section we discussed along similar lines a possible pattern of the violation of the local duality for @xmath37 decays in 1 + 3 dimensions ; in sec . [ sec : nonvanishing ] we comment on the paper @xcite and analyze effects due to nonvanishing masses of light quarks ; sec . [ sec : discussions ] presents a general discussion and conclusions . we start by formulating the problem and introducing our notation and conventions . in two - dimensional qcd the lagrangian looks superficially the same as in four dimensions @xmath38 @xmath39 denote generators of @xmath40 in the fundamental representation , @xmath41 the gluon field strength tensor and @xmath42 the quark field ( @xmath43 is a flavor index ) with a mass @xmath44 ; @xmath22 the gauge coupling constant . one has to keep the following peculiarities in mind : @xmath22 carries dimension of mass as does @xmath45 . the field strength @xmath41 on the other hand has dimension @xmath46 in our normalization , just as in four - dimensional qcd . with the theory being superrenormalizable no ( infinite ) renormalization is needed ; observables like the total width @xmath13 can be expressed in terms of the _ bare _ masses @xmath44 and _ bare _ coupling @xmath22 appearing in the lagrangian . anticipating the large @xmath26 limit we will use a parameter @xmath47 instead of @xmath22 where @xmath48 this dimensionful quantity @xmath47 , which in contrast to @xmath44 provides an intrinsic mass unit for the t hooft model , can be seen as the analog of @xmath49 of four - dimensional qcd . we need at least two quarks denoted by @xmath10 and @xmath50 with masses @xmath9 and @xmath51 , respectively , to realize heavy flavor transitions @xmath52 . for quark masses we impose @xmath53 where both @xmath54 and @xmath55 are allowed for . condition ( [ condm ] ) guarantees that the inclusive methods of ref . @xcite are applicable since it makes the energy release that controls the reliability of the expansion in four dimensions as well . ] in the weak decay large relative to the intrinsic scale @xmath47 . we will actually employ the dimensionless ratio @xmath56 as our expansion parameter . next we need to introduce a flavor - changing weak interaction ; we choose it to be of the current - current form : @xmath57 here @xmath58 is an analog of the fermi coupling constant ; it is dimensionless in two dimensions . the fields @xmath59 can be either the light quark or the lepton fields to describe nonleptonic or semileptonic decays , respectively . in 1 + 1 dimensions the axial current reduces to the vector one . the most general current - current interaction contains an additional term where the vector currents are contracted via the antisymmetric @xmath60 instead of @xmath61 . for the total width our main focus here such an additional term is of no importance . the product of scalar densities , on the other hand , is inequivalent to that of vector densities ; we will briefly discuss it , but mainly focus on the @xmath62 interaction ( [ lweak ] ) . for @xmath24 factorization holds ; i.e. , the transition amplitude can be written as the product of matrix elements of the currents @xmath63 and @xmath64 . for the inclusive widths which are discussed below the property of factorization can be expressed as follows : @xmath65 where @xmath66 and @xmath67 are defined as @xmath68 @xmath69 this factorization follows from the fact that at @xmath70 there is no communication between @xmath71 and @xmath72 currents : any gluon exchange brings in a suppression factor @xmath73 . the only difference between the semileptonic and nonleptonic widths resides in @xmath66 , in the first case @xmath74 are leptonic fields while in the second case they are the quark fields . at @xmath75 we get one and the same @xmath66 ( up to the overall normalization factor @xmath26 ) as we will show shortly . for this reason at @xmath75 the distinction between the nonleptonic and semileptonic cases is actually immaterial . at @xmath76 quark and lepton polarization tensors @xmath66 become different . this difference is proportional to powers of @xmath77 . it will be discussed in sec . [ sec : nonvanishing ] . for the time being we will treat @xmath78 s as massless leptons . the one - loop graph determining @xmath79 is depicted in fig . [ polariz ] . for a massless fermion @xmath78 we get the well - known expression , @xmath80 this expression obtained from a one - loop graph is known to be exact . if @xmath78 is a lepton field , this statement is trivial . if @xmath78 is the quark field all gluon insertions inside the loop automatically vanish due to special properties of the two - dimensional @xmath81 matrices . and any odd number of @xmath81 matrices reduces to one . ] thus , at @xmath82 the only distinction between @xmath59 being quark rather than lepton fields is an overall factor @xmath26 on the right - hand side of eq . ( [ piq ] ) . a remarkable feature of eq . ( [ piq ] ) is the occurrence of the pole at @xmath83 , which is specific for the vector interaction . this means that a pair of massless leptons produced by the vector current is equivalent to one massless boson , whose coupling is proportional to its momentum @xmath84 . in the case of the quark fields , it is known @xcite from the early days of the t hooft model that the vector current @xmath85 produces from the vacuum only one massless meson , the pion . this is readily seen by inspecting the t hooft equation @xcite . for all computational purposes the vector current @xmath86 in eq . ( [ lweak ] ) can thus be substituted by @xmath87 where @xmath88 denotes a pseudoscalar massless noninteracting field , @xmath89 in other words , the problem is formulated as the inclusive decay of the heavy quark @xmath10 into a lighter quark @xmath50 plus a sterile boson @xmath88 . more exactly , we deal with the decays of a @xmath10 containing hadron @xmath2 into a @xmath50 containing final hadronic state @xmath90 plus @xmath88 . let us pause here for two remarks . * ( i ) * the fact that the interaction vertex of the massless field @xmath88 involves @xmath91 , see eq . ( [ tildel ] ) , is most obvious when @xmath59 are quark fields . for in this case @xmath88 is the pion , as mentioned above , and the pion is coupled to the vector current @xmath92 obviously through @xmath91 . the case of the leptonic fields @xmath59 is indistinguishable ; therefore , the coupling of @xmath88 is the same . * ( ii ) * to keep the analysis to be presented below as clean and transparent as possible we want to be free of annihilation and pauli interference contributions to the total width ( at least through @xmath93 ) . this is readily achieved by assuming throughout the paper that the spectator light quark @xmath94 in @xmath2 is distinct from @xmath50 . in the leading approximation the transition operator is determined by the diagram of fig . [ transition ] , where the wavy line corresponds to the @xmath88 quantum . a straightforward calculation yields for the transition operator @xmath95 where @xmath96 is the decay width for a free quark q as evaluated in the parton model . this parton expression will serve as reference in analyzing the @xmath97 corrections to the total width @xmath98 . the @xmath1 expansion for inclusive widths of heavy flavor hadrons is constructed from the lorentz invariant weak transition operator @xcite @xmath99 the local operators @xmath4 are ordered according to their dimensions . the leading one is @xmath100 with dimension @xmath101 . higher operators have dimensions @xmath102 . by dimensional counting the corresponding coefficients are proportional to @xmath103 . the ratio of the coefficients @xmath104 is proportional to @xmath105 . the coefficients @xmath6 are determined in perturbation theory as a series in @xmath106 . it is crucial that these coefficients are saturated by the domain of virtual momenta @xmath107 and are infrared stable by construction . ( all infrared contributions reside in the matrix elements of the operators @xmath4 . ) at this point we should mention a drastic distinction between four- and two - dimensional qcd . in four dimensions the expansion parameter for the coefficients is the running coupling @xmath108 ; nonperturbative contributions to the coefficients coming from distances @xmath109 could in principle show up in the form @xmath110 where @xmath111 is some unknown positive index , not necessarily integer . in two - dimensional qcd such terms can not appear : an analog of the exponential term above would be @xmath112 . a note concerning the choice of the normalization point @xmath7 : we will imply that @xmath113 in this range there is no real dependence on @xmath7 , so we will suppress the argument @xmath7 both in the coefficient functions and operators . the coefficient functions are not the only source of a @xmath9 dependence . the matrix elements of the operators @xmath4 contain an implicit @xmath9 dependence too . ( we recall that in our formalism , unlike hqet @xcite , the fields of which the operators @xmath4 are built are the standard heisenberg operators , rather than asymptotic in @xmath9 . ) in particular , for the leading operator @xmath32 we have the following relation : @xmath114 where @xmath115 and the integration over @xmath116 allows us to omit terms which are total derivatives . in the rest frame of the hadron @xmath2 the expectation value of @xmath117 counts the number of @xmath10 quarks , @xmath118 the factor @xmath119 will be present in all matrix elements ; it corresponds to a relativistic normalization of the states , @xmath120 from relation ( [ 13 ] ) the matrix element of @xmath121 is therefore unity , up to a quadratic correction : @xmath122 moreover relation ( [ 13 ] ) provides an operator form for @xmath123 corrections . they come from @xmath124 which equals @xmath125 up to @xmath28 corrections . notice , that the operator @xmath126 is lorentz noncovariant and can not enter directly into the ope for the total width but , as we see , enters indirectly through the matrix element of the operator @xmath121 . ( [ 13 ] ) contains also the ` chromomagnetic ' operator and it looks as this operator contributes to @xmath123 corrections . it is not , however , the case . indeed , this operator can be rewritten as follows @xmath127 where the relation @xmath128 is used . taking advantage of the non - relativistic equations of motion to replace @xmath129 by @xmath130 we get ( up to total derivatives ) @xmath131 where @xmath132 stand for the generators of the color group @xmath40 . thus , the operator @xmath133 reduces to a four - fermion operator @xmath134 with coefficient @xmath135 . the absence of operators with the gluon field strength tensor @xmath136 in the ope is a specific feature of two - dimensional qcd . the physical reason for the reducibility of the gluonic operators is the absence of real gluons in two dimensions . a particular consequence of eq . ( [ og4q ] ) is that in eq . ( [ 13 ] ) the chromomagnetic operator generates @xmath137 terms only . thus we come to the following representation for the matrix element of the leading operator @xmath138 , @xmath139 where @xmath140 denote color and spinor matrices . this is in distinction with 1 + 3 qcd where the first subleading operator was @xmath141 . on dimensional grounds the operator @xmath134 , if present , could produce a _ linear _ @xmath1 correction in the total decay width . to this end the corresponding coefficient must arise in zeroth order in the coupling @xmath142 ( see the diagram in fig . [ 4q0 ] ) . for the @xmath62 weak coupling of lagrangian ( [ tildel ] ) this graph vanishes identically in the imaginary part , i m @xmath143 , provided the leptons are massless , see discussion in sec . [ sec : preliminaries ] . ( if the fields propagating in the loop are massive , the operator @xmath144 appears . the corresponding modifications are considered in sec . [ sec : nonvanishing ] . ) however , in the case of a scalar - scalar weak interaction of the form @xmath145 the graph of fig . [ 4q0 ] is not zero , and gives the following contribution to the transition operator : @xmath146 with this contribution the total width takes the form ( we put @xmath55 for simplicity ) : @xmath147 let us emphasize that , unlike four - dimensional qcd where no operator can induce a @xmath1 contribution to the total width @xcite , this can happen in two dimensions . the vanishing of i m @xmath148 for the @xmath62 weak lagrangian in the leading order is a specific dynamical feature of this particular lorentz structure of the weak interaction . note at this point that the argumentation presented in ref . @xcite was not sufficient to prove the absence of @xmath1 corrections in real qcd , see the discussion in sec . [ sub : global ] . in sec . [ ssub : fourfermion ] we will show that i m @xmath148 vanishes not only in the leading order in strong coupling but also in the order @xmath142 . the first nonvanishing contribution to i m @xmath148 comes in the order @xmath149 what leads to @xmath150 corrections to the width . next in the list comes the dimension - three operator containing six quark fields : @xmath151 along the same line of reasoning as for four - fermion operators we show that six - fermion operators appear only in the order @xmath152 . it therefore contributes in order @xmath153 . for multi - fermion operators every extra @xmath154 pair brings in an extra @xmath137 suppression . in summary : to a quite high accuracy the operator @xmath121 is the only one to contribute . the calculations are most conveniently done in the light - cone gauge . this technology can be traced back to the pioneering work of t hooft @xcite , and has been well studied in the literature . in this formalism the energy - momentum vector is described by @xmath155 so that the mass - shell condition becomes @xmath156 . let us write down the lagrangian of the model in the light - cone formalism : @xmath157 \chi_i + \frac{g^2}{2 } \left ( \sum_i \chi_i^{\dag } t^a \chi_i \right ) \frac{1}{\partial_-^2 } \left ( \sum_k \chi_k^{\dag } t^a \chi_k \right ) \label{lagr}\ ] ] in this formalism two - component quark @xmath158 fields are expressed via the one - component fermionic fields @xmath159 , @xmath160 ( in the basis where @xmath161 is diagonal ) . with the gauge fixed by @xmath162 , the @xmath163 component is expressed in terms of the quark fields . the weak interaction ( [ tildel ] ) takes the form : @xmath164^{\dag } \left[\frac{1}{i\partial_-}\chi_q\right ] \partial_- \phi \right\}\ , . \label{tilde2}\ ] ] a remarkable simplification occurs due to @xmath88 carrying light - like momentum @xmath84 : @xmath165 . we can satisfy this condition by choosing the spatial " component of the momentum @xmath166 , i.e. , @xmath167 . ( this means that the @xmath88 quantum is a left - mover . ) thus , on the @xmath88 `` mass shell '' the second term ( containing @xmath168 ) in eq . ( [ tilde2 ] ) vanishes and the weak @xmath169 coupling takes a simple form , @xmath170 here we come to a very important point . in the t hooft model non - renormalization theorem for flavor non - diagonal currents at @xmath171 arises : _ all _ corrections to the weak vertex at this point vanish . in the light - cone formalism the kinematical point @xmath171 looks analogous to the zero recoil point in four - dimensional heavy quark theory . the analogy is a superficial one , however there is no dominance of the ground state production in the t hooft model . ] . in 1 + 3 qcd flavor non - diagonal currents at the zero recoil are renormalized by radiative and power corrections . to prove the theorem let us consider the gluon corrections to the weak coupling ( [ tilde3 ] ) . to order @xmath142 the relevant graphs are depicted in fig . [ vertex ] . the feynman rules can be read off from eqs . ( [ lagr ] ) , ( [ tilde3 ] ) . in particular , the weak @xmath169 vertex is @xmath172 the graph [ vertex]@xmath173 gives rise to following expression : @xmath174 the integration over @xmath175 can easily be performed by the residue method . it is clear then that the integration over @xmath175 produces a nonzero result only in the case of opposite signs of @xmath176 and @xmath177 ( the poles should be on the different sides of the integration path ) . for @xmath178 these signs are certainly the same , @xmath179 , and there is no correction to the vertex . to finish up with the @xmath142 correction to the weak coupling we need to add graphs @xmath180 and @xmath181 of fig . [ vertex ] containing the self - energies @xmath182 and @xmath183 of @xmath10 and @xmath50 quarks . @xmath184 the integration contains a single pole only as a function of @xmath175 . unlike the previously considered vertex correction , though , the integration over @xmath175 gives a nonzero result because the integral over the large semicircle in the complex plane of @xmath175 does not vanish . the integration over @xmath185 requires an infrared regularization . following t hooft @xcite we define the integration in eq . ( [ sigma ] ) by putting a symmetric ultraviolet cutoff @xmath186 for the @xmath175 integration , and a symmetric infrared cutoff @xmath187 for the @xmath185 integration , @xmath188 then at @xmath189 the result for @xmath190 is @xmath191 \theta(|p_-|-\lambda)\;.\ ] ] the independence of @xmath190 on @xmath192 means that no @xmath193 factor appears . the first term corresponds to a shift in the quark masses , @xmath194 the second term produces a ( noncovariant ) shift in the reference point for the light - cone energy on mass shell , @xmath195 this shift produces no effect on the widths . one - loop radiative corrections thus do not affect @xmath169 transitions besides the mass shift given by eq . ( [ masscor ] ) . moreover , it stays true for higher loops as well within the t hooft model . for in the limit @xmath196 there are no fermion loop insertions into the gluon propagators . then the higher loop corrections to the vertex , as well as to the self - energy , vanish in the way discussed above since the integration over @xmath175 yields zero . notice that the non - renormalization theorem we derive within the t hooft model is a stronger statement than the one about zero recoil in four - dimensional qcd where radiative and power corrections break the non - renormalization of flavor non - diagonal currents . now it is simple to account for higher orders in the coefficient @xmath197 of the leading operator @xmath198 . to zeroth order in @xmath142 this coefficient was determined in sec . [ sec : preliminaries ] , see fig . [ transition ] and eq . ( [ cqqzero ] ) . as just discussed higher loop corrections merely shift the quark masses , eq . ( [ masscor ] ) , and therefore we get the coefficient @xmath197 in all orders , @xmath199 combining this result with eq . ( [ qq ] ) and with the suppression of the four - fermion operators , see sec . [ ssub : fourfermion ] , we conclude that * ( i ) * : : there is no @xmath1 corrections in the total width , much in the same way as in actual qcd @xcite ; * ( ii ) * : : corrections @xmath123 , @xmath137 and @xmath28 to the total width are associated exclusively with the operator @xmath32 . in sec . [ sec : match ] we will prove a stronger statement : irrespective of the explicit form of these corrections , the hadronic saturation yields exactly the same result for the total width as the contribution of @xmath200 in ope . the expression ( [ lnp ] ) for @xmath33 refers to a low normalization point , @xmath201 . in order to calculate the matrix element of @xmath32 over @xmath2 we will need to express @xmath32 in terms of @xmath202 . it goes without saying that the operator @xmath32 must be taken at the same normalization point . then , the resulting series in @xmath106 cancels against a similar expansion coming from the operator @xmath23 ; there is no @xmath47 dependence in the product @xmath203 . this can be seen by rewriting @xmath138 in terms of the unrenormalized one - component field @xmath202 and mass @xmath9 : @xmath204 in evolving down to @xmath7 , higher orders lead to the substitution @xmath205 in this relation as well . with the quark mass substitution being the only effect of the radiative corrections we have @xmath206 the statement that the product @xmath207 is renormalization group invariant is trivial , of course . a nontrivial part of the result is encoded in eq . ( [ msdop ] ) , which is valid to all orders in @xmath22 . one could obtain this result by doing calculations at @xmath208 when the mass of the @xmath10 quark coincides with its `` bare '' value @xmath9 , at @xmath209 , or at @xmath210 , when a non - logarithmic evolution of the @xmath198 operator and its coefficient functions must be taken into account , the outcome is the same , see eq . ( [ msdop ] ) . to make contact with the t hooft equation ( i.e. to calculate @xmath100 in terms of the t hooft wave function defined for bare quantities ) we will need eq . ( [ msdop ] ) at the ultraviolet cutoff . note that it can be conveniently rewritten as @xmath211 in sec . [ sub : sumrules ] we will find the matrix element of @xmath212 and show that the corresponding expression for the total width coincides with the one obtained through the hadronic saturation . as discussed above for the current - current weak interactions four - fermion operators do not arise to zeroth order in the strong coupling . diagrams generating four - fermion operators in the @xmath142 order are shown in fig . [ 4q2 ] . the light - cone gauge turns out to be again a convenient tool to use . let us start for illustration with the simple one - loop diagram of fig . [ transition ] . feynman rules in the light - cone gauge , see sec . [ ssub : nonrenormalization ] , lead to the following expression @xmath213 here @xmath214 appears from the cut of the @xmath88 propagator , the cutting of the @xmath50 quark propagator done by taking of imaginary part . the integration over @xmath185 is immediate due to @xmath215 root of delta function ( the other root , @xmath216 , gives the same contribution , so just a factor 2 ) @xmath217 \;.\ ] ] it means that the term @xmath218\chi_q\ ] ] appears in the transition operator . in the zeroth order in the t hooft coupling the equation of motion for the @xmath202 field is @xmath219 in the rest frame @xmath220 , and we reproduce eq . ( [ cqqzero ] ) . let us now apply the same technique to the loop part in fig . [ 4q2]@xmath180 in the limit of vanishing gluon momentum . integrating over @xmath185 we get @xmath221 ^ 2}=\pi \;.\ ] ] it produces the term @xmath222 in the transition operator , note that the overall factor is the same as in eq . ( [ lc - trans2 ] ) . summing up @xmath223 and @xmath224 results in the substitution of @xmath225 by @xmath226 . in this order the equation of motion ( [ eqmotion ] ) is also should be modified by the same substitution . net result is that no change in ope coefficients is produced by the loop in in fig . [ 4q2]@xmath180 . note that it is true not only for vanishing momentum of gluon field but for any soft field as well , in other words , terms with derivatives of @xmath227 do not appear in the transition operator in one - loop order . note also that if extra gluons are emitted from the loop we get zero for the diagram . indeed , it increases the power in the integrand of eq . ( [ lcloopb ] ) and the integral over the large semicirle in the complex plane of @xmath175 vanishes . it is the reason why diagrams of the type of fig . [ 4q2]@xmath180 give no rise to multi - fermion operators . to finish up with multi - fermion operators we need to account for diagrams of the type given in fig . [ 4q2]@xmath173 . the feynman expression for this diagram after integrating over @xmath185 is @xmath228 ^ 2}\ ; \frac{1}{[(p_q - p_q)_-]^{2 } } = \frac{\pi}{[(p_q - p_q)_-]^{2 } } \;.\ ] ] it is simple to check then that the diagram [ 4q2]@xmath173 cancel out against similar diagrams where the gluon exchange is between @xmath50 and @xmath10 quarks . in case of extra gluon insertions in one loop ( relevant for six - fermion and higher dimension operators ) we get a vanishing result right away . thus , we proved that four - fermion and multi - fermion operators do not arise at the level of one loop . they show up at level of the second loop , see the diagram [ 4q4 ] for four - fermion operator . the dimensional counting reveals then that four - fermion operators give @xmath150 correction to the total width . 8 cm putting everything together we get the ope representation for the inclusive width : @xmath229 = \gamma _ q \left [ \frac{\langle h_q|\chi _ q^{\dagger } \frac{m_q}{i\partial _ -}\chi _ q |h_q \rangle}{2m_{h_q } } + { \cal o}\left(\frac{1}{m_q^5}\right ) \right]\ , . \label{gammadual}\ ] ] we have thus obtained a very simple result : * the partonic expression @xmath230 represents the asymptotic term for @xmath231 . * there is no @xmath1 contribution in ope as long as the weak interactions are of the @xmath62 type . * through order @xmath28 only a single operator contributes , @xmath121 . * the leading correction @xmath232 enters through the expectation value + @xmath233 . the second part of eq . ( [ gammadual ] ) has been written in terms of the light - cone operators to provide a way of rewriting the matrix element in terms of the t hooft wave function of the hadron @xmath2 . the ope result for the inclusive width can be recast in terms of the sum over exclusive hadronic channels . this will be proven next . with 1 + 1 qcd describing manifestly confining dynamics , its spectrum consists of mesonic quark - antiquark bound states . in @xmath24 limit these mesons are stable in regard to strong decays . the masses and the light - cone wave functions @xmath234 ( with @xmath235 $ ] having a meaning of a portion of momentum carried by the quark ) of these mesons can be determined as eigenfunctions and eigenvalues of the t hooft equation . in particular , the initial state @xmath236 $ ] is the ground state in the sector with the the heavy quark @xmath10 and the spectator antiquark @xmath237 . its wave function @xmath238 satisfies the following equation : @xmath239 \varphi _ { h_q}(x ) - \beta ^2 \int_0 ^ 1{\rm d}y \,\frac{\varphi _ { h_q}(y)}{(y - x)^2 } \label{thooftin}\ ] ] where @xmath240 denotes the mass of the spectator antiquark and the integral is understood in the principal value prescription . the solutions to the equation are singular at @xmath241 and @xmath242 where their behavior is given by @xmath243 and @xmath244 , respectively , with @xmath245 defined by the following conditions : @xmath246 the masses @xmath247 and wave functions @xmath248 of final mesons @xmath249_n$ ] are defined by the same t hooft equation with @xmath9 substituted by @xmath51 : @xmath250 \varphi _ n(x ) - \beta ^2 \int_0 ^ 1{\rm d } y \,\frac{\varphi _ n(y)}{(y - x)^2 } \label{thooftfi}\ ] ] the functions @xmath248 form a complete basis , i.e. , @xmath251 let us find out now how an exclusive width @xmath252 of @xmath253 decay is expressed via wave functions @xmath238 , @xmath248 of initial and final mesons , @xmath254 ^2\ ] ] where the factor @xmath255 is the lorentz invariant phase space ( lips ) of two - particle final state and for the matrix element we have used eq . ( [ tilde3 ] ) in the kinematics where the @xmath256 momentum @xmath84 is @xmath257 it is simple then to write the matrix element of @xmath258 in terms of the t hooft wave functions , @xmath259 using the completeness condition ( [ on ] ) we can derive sum rules for these partial widths by weighing them with powers of @xmath260 . the first one is @xmath261 note that the sum runs over _ all _ states @xmath262 including those unaccessible in the real decays of @xmath2 , i.e. with masses @xmath263 . these transitions are still measurable by the process of inelastic lepton scattering off @xmath2 meson . this sum rule is an analog of first bjorken sum rule and was discussed in @xcite . to get next sum rules let us multiply eq . ( [ thooftin ] ) by @xmath264 and eq . ( [ thooftfi ] ) by @xmath265 , respectively . after integrating over @xmath116 and subtracting we find : @xmath266 two more sum rules then arise : @xmath267 @xmath268 the second and third sum rules differ from the first one in two aspects : they depend on the quark masses @xmath9 and @xmath51 explicitly and the integral over the wave function is not fixed by a normalization condition ; it can , however be calculated in the t hooft model . one should note that while the integrand @xmath269 , is singular at @xmath241 , it is still integrable , since @xmath270 . note also that expanding the second sum rule ( [ sr2 ] ) in @xmath1 to the linear order we reproduce the corresponding sum rule of ref . @xcite . the sum rules above provide us with detailed information on the saturation of the sums over the final hadronic state . the quantity @xmath271 can be interpreted as a normalized probability of producing the state @xmath272 . indeed @xmath273 according to the first sum rule ( [ sr1 ] ) . then the sum rule ( [ sr2 ] ) implies @xmath274 if both masses @xmath240 and @xmath51 are smaller or of order of @xmath47 we conclude that @xmath275 here we have anticipated the result for @xmath276 from eq . ( [ expan ] ) in the next subsection , in conjunction with eq . ( [ mh ] ) . the reason for @xmath277 is clear on the physical grounds : in the partonic approximation the final state is formed by the quark @xmath50 with the momentum @xmath278 and by the spectator antiquark @xmath279 with the momentum of order @xmath47 . the sum rule ( [ sr3 ] ) ( after subtracting the square of the second sum rule ( [ sr2 ] ) ) determines the dispersion : @xmath280 what about higher moments ? it is not difficult to see that the next one , @xmath281 , is a divergent sum because @xmath282 would no longer be integrable . it defines the asymptotics of @xmath252 at large @xmath272 , @xmath283 let us recall @xcite that @xmath284 for high excitations , @xmath285 . we will see in the next subsection that the asymptotics ( [ largen ] ) matches the contribution of the four - fermion operators in ope . armed with exact sum rules ( [ sr1 ] ) , ( [ sr2 ] ) , ( [ sr3 ] ) we are well prepared to verify a perfect match between the ope result and the expression obtained by summing over hadronic final states . from the second sum rule ( [ sr2 ] ) we have for the total semileptonic width @xmath13 the following relation @xmath286 the second term is actually positive ( @xmath252 defined by eq . ( [ excl ] ) is negative at @xmath263 ) . using eq . ( [ largen ] ) its size can be estimated @xmath287 thus we have derived from the t hooft equation the following result for the inclusive width @xmath288\ , .\ ] ] this expression coincides with the ope result of eq . ( [ gammadual ] ) as seen by rewriting the matrix element in eq . ( [ gammadual ] ) in terms of the ground state wave function @xmath289 , @xmath290 where , besides normalization factors , we have used also the substitution @xmath291 . this completes the proof of the perfect matching between ope and the hadronic saturation through the order @xmath28 . let us stress that the matrix element ( [ m.e . ] ) given by the integral over the ground state wave function is implicitly @xmath9 dependent , its leading term is 1 followed by @xmath123 and higher terms ( see the discussion in sec . [ sub : catalog ] ) . in the t hooft model one can , of course , evaluate the matrix element explicitly although it is not relevant to our main objective probing the quark - hadron duality . the absence of @xmath1 corrections was demonstrated in sec . [ sub : catalog ] by operator methods . let us show now that the same statement can be derived from the t hooft equation as well . to this end we use the approach of ref . @xcite to the heavy quark limit , generalizing it to include @xmath123 corrections . instead of @xmath116 , the appropriate variable for the large mass limit is @xmath292 an expansion of the t hooft equation in @xmath1 ( after a substitution of the new variable ) and the virial theorem lead to the following relation for the meson mass , @xmath293 where averaging is over the @xmath2 meson wave function @xmath294 . as compared with ref . @xcite we have added a @xmath106 term . its origin is simple : it accounts for the renormalization of the heavy quark mass . note that @xmath295 provided @xmath296 . we also need a similar expansion for the integral entering eq . ( [ ghgq ] ) , @xmath297 substituting eqs . ( [ mh ] , [ expan ] ) in eq . ( [ ghgq ] ) we have , @xmath298 this expansion should be compared with the operator representation ( [ qq ] ) . the @xmath1 expansion of @xmath299 produces the same @xmath123 term ; the part @xmath300 comes from the expansion of @xmath301 , see eq . ( [ corrqq ] ) . note that without the @xmath302 term the correction to 1 is negative , i.e. @xmath303 one more comment about @xmath150 terms . in the ope approach they are due to the four - fermion operators generated by the graph in fig . although the corresponding ope coefficients are not calculated , the consideration above shows that the contribution of the four - fermion operators is dual to the sum of @xmath252 with @xmath304 for final state mesons , i.e. channels kinematically inaccessible in the decay . having established a perfect match between the ope prediction for the total width and the result of the saturation by exclusive decay modes , through @xmath305 , we must now turn to the issue of where the ope - based prediction is supposed to fail . the failure usually goes under the name of duality violations " , a topic under intense scrutiny in the current literature . the definition of what duality violation is varies from publication to publication . quite often , the researchers in the field stick to a vague notion of deviations of certain rates for processes involving hadrons from the underlying partonic rates " . this is , for instance , the convention of ref . @xcite where duality is understood as the coincidence with the parton - model prediction . if so , any nonperturbative contribution to the given rate would be interpreted as a duality violation " , which does not make much sense to us . we must precisely define what is meant by duality and its violations . assume that a certain process is amenable to calculations within ope . this means that an appropriate euclidean quantity can be chosen , and the ope series can be constructed . this series presents the quantity of interest as an expansion in an inverse large parameter , e.g. @xmath306 or @xmath307 . the very same quantity can be expressed as a dispersion integral over the imaginary part defined in minkowski space . in @xmath308 annihilation the imaginary part coincides with @xmath309 , in the transition amplitudes for heavy flavors the imaginary part reduces to semileptonic spectral densities , etc . in order to treat the nonleptonic decays in the same vein one can introduce a spurion in the weak vertex , carrying a momentum @xmath50 . in other words , let us substitute the weak lagrangian by @xmath310 where @xmath311 is a spurion field . now let us consider the forward amplitude @xmath312 of the process @xmath313 as a function of @xmath314 . this variable @xmath315 plays the same role as @xmath316 in @xmath308 annihilation . the total nonleptonic width is given by @xmath317 at @xmath318 . we are free to consider @xmath319 in the complex @xmath315 plane where it has two cuts : at @xmath320 and at @xmath321 ( the second cut is due to @xmath322 channel ) . choosing a reference point @xmath323 far away from both cuts but closer to the first one we can express @xmath324 as a dispersion integral over the discontinuity across the cuts . on the other hand at the very same point @xmath323 one can apply the operator product expansion for calculating @xmath324 in terms of matrix elements of local operators , @xmath325 . this gives sum rules which allow us to determine @xmath319 at large @xmath315 , in particular , at @xmath318 . this is fully analogous to what one does in @xmath308 annihilation for @xmath326 . in both cases smoothness is assumed ( of course , in in @xmath308 annihilation all positive values of @xmath315 are accessible and one can check this assumption while in the case of nonleptonic decays @xmath327 is fixed ) . needless to say that the total semileptonic widths can be treated along the same lines , the only difference is the presence of leptons in the intermediate states . in the semileptonic decays ope allows to predict , additionally , various distributions in the lepton momenta . this is , probably , the reason why it is usually claimed that the status of duality is more solid in the semileptonic decays . to show that it is not the case let us consider the semileptonic decays with the light quark in the final state . the ope - based predictions for the spectral distributions are valid almost everywhere ; they fail only in the end - point domain @xcite . for this reason the total semileptonic widths can not be obtained by integrating over the spectrum if we want a prediction which includes the linear in @xmath1 corrections , it is why the argumentation in ref . @xcite was not sufficient to prove the absence of @xmath1 corrections . nevertheless , the statement of absence of such corrections in the total semileptonic widths can certainly be justified by the procedure described above for the nonleptonic widths . thus , we see that the theoretical status of all these processes @xmath308 annihilation , semileptonic and nonleptonic decays of heavy flavors is basically the same . by performing an appropriate expansion of the dispersion integral we obtain sum rules relating certain moments of the imaginary part of transition amplitude to matrix elements of consecutive terms in the ope series constructed in the euclidean domain . the predictions obtained in this way will be referred to as _ global duality_. taken at their face value , they are exact , to the extent we can calculate the coefficient functions and matrix elements of the operators involved in ope . no additional assumptions are made . the predictions obtained in this way are consequences of fundamental qcd . therefore , it does not make any sense to speak about violations of the global duality . one can only speak of the precision of calculation of the coefficient functions and determination of the matrix elements . unfortunately the term _ global duality _ is often used in a loose and ambiguous sense . it is applied indiscriminantly to integrals over the spectral densities with the weight functions chosen _ ad hoc_. our definition is narrower : it refers only to those specific integrals which emerge from the dispersion representation . the notion of _ local duality _ on the other hand requires further assumptions . assume that we want to predict imaginary parts ( spectral densities ) point by point , at large energies ( or @xmath328 ) . _ if _ one assumes that the spectral densities at the given energy are smooth , then from the moment integrals we can certainly predict the densities themselves . this amounts to an analytic continuation of the ope series ( truncated in a certain way ) , term by term from the euclidean to minkowski domain , with the subsequent calculation of the imaginary parts of each individual term in the series . the prediction obtained in this way is evidently a smooth function of the parameters . we then compare this prediction with the quantity measured in terms of hadronic contributions . the difference between the ope - based smooth result and the experimental hadronic measurement is referred to as the _ duality violation _ meaning the violation of _ local duality_. by its nature the ope results are series in powers of @xmath329 and do not account for terms like @xmath330 $ ] ( in the euclidean domain ) . although such terms are due to large distances , a signal of their appearance could show up in the short distance ope series in the form of a factorial divergence of the series in higher dimensions . the situation is reminiscent of that in the perturbative expansion . the divergent @xmath331 series ( e.g. due to infrared renormalons ) give rise to terms @xmath332 although such terms can appear even in the absence of renormalons ( for instance , as the quark condensate ) . in other words , the ope construction accounts properly for short distance singularities while the exponential terms are due to large distances being nonsingular at short distances . thus , the duality violation is something we do not see in the ( truncated ) ope series . the duality - violating terms are exponential in the euclidean domain and oscillating ( like @xmath333 $ ] ) in the minkowski domain . from this standpoint there is no distinction between , say , the total @xmath308 annihilation cross section or the semileptonic rates of heavy flavors , on the one hand , and the nonleptonic rates of heavy flavors , on the other . sometimes it is claimed that the former processes are pure " while the latter are impure " ; it is even asserted that duality follows from ope in the first case while it has no theoretical justification in the second case " . we assert that a duality violating exponential / oscillating component , associated with the neglected tails of ope , is present in all processes , and the only physically meaningful question is its magnitude , as a function of large parameters ( e.g. a momentum transfer or @xmath9 ) and specific details of the process under consideration . the appearance of duality violations in the form of oscillating terms is evident in the t hooft model where the spectral density is formed by zero - width discrete states . indeed , each time a new decay channel opens @xmath334 experiences a jump ( @xmath13 is continuous ) , so that immediately above threshold @xmath334 is larger than the smooth ope curve , in the middle between two successive thresholds it crosses the smooth prediction , and immediately below the next threshold @xmath334 is lower than the ope - based expectation . the amplitude of oscillations can be estimated as follows . let us present the total width @xmath13 as @xmath335 widths @xmath252 are exclusive widths of two - body decays , @xmath336 , where @xmath262 is the @xmath272-th excited @xmath337 state with the mass @xmath247 . for @xmath263 widths @xmath252 are not , of course , physical ones for @xmath2 decays but they are well defined . we have used this presentation in sec . [ sub : matching ] where it was shown that the first term can be related to the wave function of @xmath2 state on one hand and to the matrix element of @xmath338 operator on the other . it is clear that the first term in eq . ( [ g - g ] ) is a smooth function of @xmath9 and contains no nonanalytic terms we are going after , they are in the second one . thus we need to to know @xmath339 for @xmath247 in the vicinity of @xmath327 . for @xmath340 we found in sec . [ sub : sumrules ] that @xmath341 , see eq . ( [ largen ] ) . to extrapolate to the vicinity of @xmath342 we account for the threshold factor , @xmath343 . the coefficient in this dependence can be fixed by duality of the second term in eq . ( [ g - g ] ) to four - fermion operators @xmath134 , discussed in sec . [ sub : matching ] , @xmath344 we did not calculate coefficients @xmath148 but we found that up to numerical factor @xmath345 assuming @xmath346 we estimate @xmath347 . then our model for @xmath252 in the range @xmath348 is @xmath349 the sum in in eq . ( [ mdl ] ) was approximated by the integral using @xmath350 . now we can evaluate the sum ( [ mdl ] ) with the better accuracy accounting for small nonanalytical terms . the result is @xmath351\ ; , \nonumber\\ \delta \gamma^{\mbox{\tiny osc } } & = & \frac{3}{2 } \pi^3 g^2\beta\left(\frac{\beta}{m_{h_q}}\right)^8\,\left[x(1-x)-\frac{1}{6}\right]\end{aligned}\ ] ] where @xmath352 the smooth part @xmath353 in eq . ( [ md2 ] ) is given by same ope term of eq . ( [ mdl ] ) we discussed above plus higher in the power of @xmath1 corrections . the nonanalytic in @xmath354 part @xmath355 oscillates with period @xmath356 , see its plot in fig . [ local ] . the amplitude of oscillation is @xmath357 note that the derivative @xmath358 contains discontinuities at thresholds , the amplitude of oscillations is larger for the derivative , @xmath359 the oscillations under discussion can not be produced by any truncated ope series , they are not seen in the ope . thus the estimate ( [ oscil ] ) gives the actual scale of the expected duality violations in the problem at hand . of course , this estimate is obtained within a specific model for @xmath252 . the gross features of the result are independent of the model , however . they are determined only by the fact that the resonances have zero widths . it should be noted that the limit @xmath70 presents a scenario which maximizes duality violations . in this limit the thresholds open `` abruptly '' , right at the position of the resonances , since the resonance widths vanish . in the real world of finite @xmath26 the highly excited states have finite widths , and this effect , on its own , smears the hadron - saturated cross sections dynamically . if in the zero width approximation the oscillating duality violating component is suppressed only by powers of a large parameter ( @xmath1 in the case at hand ) , switching on finite widths will further suppress the oscillating component exponentially , see sec . [ sub : tau ] and ref . @xcite for further details . from the considerations above we conclude that : ( i ) : : oscillating terms violating local duality are definitely present in the total decay rate ( considered as a function of @xmath9 ) ; ( ii ) : : amplitude of oscillations is @xmath360 , i.e. strongly suppressed ; ( iii ) : : if we could average over @xmath9 in a sufficiently large interval the power suppression of the oscillations would turn into exponential suppression ( in actual qcd , with @xmath361 , the finite resonance widths do a similar job ) . then it is perfectly legitimate to consider the ope - based predictions beyond @xmath362 . with this understanding in mind we now turn to the discussion of duality violations in actual four - dimensional qcd . let us discuss a quantity of practical interest in 1 + 3 dimensions along similar lines , namely the normalized hadronic @xmath37 width @xmath363 : @xmath364 it can be expressed in terms of spectral densities @xmath365 and @xmath366 in the vector and axial - vector channels , respectively , @xmath367 = \frac{i_0(m_\tau^2)}{m_\tau^2 } -3\ , \frac{i_2(m_\tau^2)}{m_\tau^6}+ 2\,\frac{i_3(m_\tau^2)}{m_\tau^8 } \ , , \label{72}\ ] ] where the moments @xmath368 are defined as @xmath369 \;. \label{in}\ ] ] while @xmath37 decays represent a simpler dynamical problem than the weak decays of heavy flavor hadrons we have to simplify it further still before we can arrive at some definite conclusions . to estimate the oscillating contribution to @xmath363 which constitutes duality violation that can not be seen in a truncated ope we consider the limiting cases of @xmath370 and @xmath26 large . we will show that , adopting the resonance model motivated by two - dimensional qcd , for @xmath24 and @xmath370 large , yet finite , the duality violation in @xmath363 scales as @xmath371 ; for @xmath372 with @xmath26 large , though finite , the oscillating term is suppressed exponentially . our consideration will be admittedly illustrative . one should not take literally the numbers we will obtain for many reasons : first of all the @xmath37 mass is not much larger than the spacing between the resonances , second , @xmath26 is not large enough to warrant the zero width approximation . still we believe that the consideration is instructive in a qualitative aspect . for large @xmath26 the spectrum of 1 + 3 qcd is expected to consist of an infinite comb of narrow resonances in complete analogy to the t hooft model @xcite . to keep the closest parallel to it we further assume that the high excitations in a given channel ( e.g. the vector channel ) are equally spaced in @xmath373 . this agrees with the general expectation of a string - like realization of confinement leading to asymptotically linear regge trajectories . the masses of the excited states in , say , the @xmath374 channel are then given . the distinctions between these two scenarios are irrelevant for our discussion . ] by @xmath375 @xcite , with @xmath376 being the slope of the regge trajectory ( for a review see @xcite ) . experimentally one finds @xmath377gev@xmath378 . for large values of @xmath315 the spectral densities for both the vector and axial - vector channels will approach the form : @xmath379 where a special notation @xmath380 is introduced for @xmath381 . equation ( [ spectdens ] ) is clearly not expected to hold at moderate and small values of @xmath315 where the vector and axial - vector channels are drastically different and the resonances are not equidistant . however , details of the spectral densities at small @xmath315 play no role in duality violation . the contribution of any particular resonance of mass @xmath382 to @xmath383 , according to eq . ( [ 72 ] ) , is given by a simple polynomial in @xmath384 ( times the step function @xmath385 ) . therefore , variations of properties of resonances below a certain fixed mass @xmath7 change only the regular terms of the @xmath384 expansion , but have no impact on the oscillatory component . from eq . ( [ 72 ] ) it is clear that such variations change only coefficients of the @xmath384 , @xmath386 and @xmath387 terms . it will be clear in what follows that the formal ope for @xmath383 exactly reproduces these three expansion coefficients as well . the spectral density in eq . ( [ spectdens ] ) is dual to the parton model result ; i.e. , it coincides with it after averaging over energy , @xmath388 thus , the asymptotic prediction for @xmath383 at @xmath389 is @xmath390 the sum over resonances in @xmath383 is easily calculated analytically : for the spectral density of eq . ( [ spectdens ] ) it is @xmath391\,\left(\frac{\sigma^2}{m_\tau^2}\right)^4 , \label{n9}\end{aligned}\ ] ] where @xmath392 we presented the result as a sum of two functions of @xmath393 , the first one , @xmath394 , is a smooth function expandable in @xmath384 . the second one , @xmath395 , oscillates with the period @xmath380 ; its average vanishes , see the plot of @xmath396 in fig . [ oscillation ] . let us show now that @xmath394 coincides with the ope prediction in the model . power corrections can be presented in the following way : @xmath397 where the `` condensates '' @xmath398 are @xmath399 \;. \label{tildin}\ ] ] this integral representations for the `` condensates '' @xmath398 follows from eqs . ( [ 72 ] ) , ( [ in ] ) if one assumes that the spectral densities approach their asymptotic limits faster than any power of @xmath400 . in the model at hand , with the comb - like spectral density , the integral representation ( [ tildin ] ) requires regularization . as a regularization one can introduce the weight factor @xmath401 , taking the limit @xmath402 at the end . with this regularization , @xmath403 from eq . ( [ n9 ] ) is reproduced . to justify the procedure it is instructive to make one step back and follow more literally the original ope procedure . namely , our primary object of interest is the euclidean polarization operator @xmath404 the original meaning of @xmath398 is the coefficients in the asymptotic expansion of @xmath405 at @xmath406 : @xmath407 the comb of model of eq . ( [ spectdens ] ) was considered in ref . @xcite , @xmath408 \:+\:{\rm const } \ ; , \label{n4}\ ] ] where @xmath78 is euler s @xmath78 function . the asymptotic expansion of @xmath405 in the model takes the form @xmath409 \:+\:{\rm const } \ ; , \label{n5}\ ] ] where @xmath410 stand for the bernoulli numbers . taking the coefficients of @xmath306 , @xmath411 and @xmath412 terms from this equation we find the consistency with @xmath403 of eq . ( [ n9 ] ) . ( the term @xmath411 is absent and @xmath412 is defined by @xmath413 . ) note that the spectral density ( [ spectdens ] ) is not literally `` qcd - compatible '' : the corresponding @xmath405 has the @xmath306 nonperturbative correction forbidden in qcd @xcite . this can be easily cured by adding the resonance with @xmath414 with a half weight , which just would amount to adding @xmath415 to @xmath416 . since this obviously does not change @xmath395 at any value of @xmath417 , this is inessential for us . let us discuss now the duality - violating @xmath418 ( see fig . [ oscillation ] ) . its dominant component scales as @xmath386 . it is intriguing to note that the very same scaling law was obtained in ref . @xcite from totally different considerations invoking instantons . this oscillating component vanishes at @xmath417 corresponding to the new thresholds , and at one point in the middle between the successive resonances ; only the second derivative of @xmath383 has a jump at the thresholds , @xmath419 this is the consequence of the threshold factor @xmath420 in eq . ( [ 72 ] ) . one power in it is just the two - body phase space factor @xmath421 . in @xmath422 dimensions one would have instead @xmath423 , the threshold singularity , and the duality - violating component would be enhanced correspondingly . the average of @xmath395 vanishes while the amplitude of oscillations amounts to @xmath424 it is interesting that , in spite of the fact that @xmath425 is given by a polynomial between the thresholds , the whole function is well approximated by @xmath426 note that the numerical coefficient in eq . ( [ n13 ] ) is rather small , compare e.g. to eq . ( [ jump ] ) . this suppression is related to the fact that the characteristic scale is @xmath427 rather then @xmath380 . taking our estimate of the oscillation amplitude at its face value and using the actual value of the @xmath37 mass in eq . ( [ n12 ] ) we find @xmath428 . it is clear that this is a very crude estimate given the fact that in the actual @xmath37 decay @xmath429 and we deal with one oscillation at most . in the real world with @xmath430 we expect a further suppression of deviations from duality due to the nonvanishing widths of the resonances naturally smearing out the amplitude of the oscillation . a rough estimate of this effect can be given in close analogy to ref . let us introduce a dimensionless constant @xmath431 representing the width - to - mass ratio : @xmath432 i.e. , @xmath431 stays finite for large @xmath26 . one actually guestimates @xmath433 . then we infer ( see @xcite for details ) @xmath434 the power - suppressed oscillations eventually turn into exponentially suppressed , although at a larger energy . the work @xcite stimulated our interest in the t hooft model as a laboratory for exploring heavy quark expansions in inclusive decays , and the implementation of duality . the authors of ref . @xcite compared the decay width of a heavy flavor hadron in the parton approximation with the result obtained by summing over all exclusive transition rates for @xmath436 . a systematic excess of the total width @xmath13 over its parton value @xmath437 was observed and was fitted to be @xmath438 the authors interpreted this access as a violation of duality . according to our understanding ( see sec . [ sub : global ] ) it should rather be called breaking of ope . our analytical treatment does not support such a conclusion . in particular , we have proved the absence of linear in @xmath1 corrections not only by the ope method but by the direct analysis of the t hooft equation ( see sec . [ sec : match ] ) . although we tried to closely follow the analysis of ref . @xcite , still there is a difference of kinematical nature . we considered the @xmath78 fields ( leptons or quarks ) to be massless , while @xmath439 in ref . the choice of @xmath440 allows us to limit ourselves to the point @xmath83 where great simplifications occur , in particular , only the massless pion state is produced in the @xmath441 channel . analytic solution of the problem turns out to be possible . we have checked that the analytical expression for the triple overlap integral of ref . @xcite reduces at @xmath83 to a simple overlap integral ( [ excl1 ] ) of two wave functions . the simple structure of ( [ excl1 ] ) combined with the completeness of the wave functions is sufficient to prove a perfect match between ope and hadronic saturation , at the level of @xmath28 . to make full contact between our results and those of ref . @xcite we must now consider the impact of @xmath76 . needless to say that at @xmath442 the parton result for @xmath96 changes , @xmath443\;.\ ] ] this effect was certainly included in the analysis of ref . it is also accounted for in ope as a change of the coefficient of the operator @xmath138 . the leading effect due to @xmath76 is linear in @xmath77 , however . thus , one can wonder whether it produces @xmath1 corrections . in the next subsection we will show that the linear in @xmath77 corrections to the total width are suppressed as @xmath137 . moreover , this is a leading effect which produces a distinction between semileptonic and nonleptonic total widths , all other effects which differentiate them are suppressed as @xmath28 . it is clear then that the @xmath1 violation of duality claimed in ref . @xcite if it would be present in the nonleptonic width must have been present in the semileptonic width as well . corrections @xmath137 come also from quadratic in @xmath77 terms in ope . as it was mentioned above these corrections do not differentiate semileptonic and nonleptonic widths . we estimate them in sec . [ sub : correction2 ] . we also estimate in sec . [ sub : local ] effects of novanishing @xmath77 for violations of local duality . overall , we conclude that the ope approach shows that the nonvanishing @xmath77 results in @xmath137 corrections which are numerically small and can not explain the alleged deviation ( [ deviat ] ) . on the hadronic saturation side we have checked that the triple overlap integral of ref . @xcite is expandable in @xmath77 , and the leading correction is quadratic in @xmath444 . assuming that @xmath445 and performing an _ analytic _ summation of the widths using the expressions of ref . @xcite for the amplitudes in conjunction with the sum rules for the hadronic polarization tensor @xmath446 similar to those in eqs . ( [ sr1],[sr2],[sr3 ] ) , we obtained exactly the same @xmath447 correction as in eq . ( [ gamnot ] ) . this holds for the inclusive width smeared over a small interval of masses as discussed in sec . [ sub : local ] . moreover , we checked the exact matching with ope at the level @xmath137 . all effects due to @xmath76 reside in @xmath79 , see eq . ( [ pi1 ] ) . the linear in @xmath77 part in ope for @xmath79 is @xmath449 it is easy to see that this effect is nothing but a shift of the pion ( @xmath450_0 $ ] ) mass from zero , @xmath451 indeed , comparing eq . ( [ piq ] ) and eq . ( [ linm ] ) we see that the latter is the first order term in @xmath452 expansion of the pion pole @xmath453 in @xmath454 . thus , in order to take into account linear in @xmath77 effects in the transition operator all one needs to do is to calculate the decay @xmath455 with the nonvanishing pion mass . the result is @xmath456 at large @xmath9 it falls off as @xmath137 . an extra suppression @xmath457 is specific for two dimensions . as for for the numerical value of the correction ( [ psicor ] ) we we will substitute @xmath458 in the chiral limit @xcite . for the value of @xmath459 adopted in ref . @xcite we get @xmath460 the analysis of the previous subsection refers to the operator @xmath461 in ope for the total width . another operator generated due to @xmath442 is the four - fermion operator of the type @xmath462 . it appears from the graph of fig . [ 4q0 ] with lepton lines substituted by @xmath78 lines . calculation of this graph is a simple exercise . the result for the corresponding correction to the width can be presented in the following form @xmath463 up to the factor @xmath26 the same contribution appears in the semileptonic width . in difference with the operator @xmath461 the large @xmath26 limit does not allow us to factorize the matrix element of eq . ( [ mcorr ] ) . we will use the factorization to get an estimate , @xmath464 as in the previous subsection we use the chiral limit value @xmath465 of the vev @xcite and @xmath459 for the numerical estimate , @xmath466 here we discuss the impact of new thresholds opening in the spectral density of the vector @xmath467 currents , as @xmath9 increases . at @xmath440 the duality in the @xmath468 correlation function is perfect , since , due to bosonization , the theoretical expression for this correlator reduces to exactly one massless state propagation with a known coupling constant . if @xmath76 then higher @xmath469 $ ] mesonic states appear in the imaginary part of @xmath470 with residues proportional to @xmath471 . to calculate the dependence of the total width @xmath13 on @xmath9 near thresholds , i.e. near @xmath472 } + m_k^{[q{\bar q_{sp } } ] } \;,\ ] ] we need to find the exclusive width @xmath473_n + [ q{\bar q_{sp}}]_k)$ ] . we did it in sec . [ sub : oscillating ] for @xmath474 when only the @xmath414 massless @xmath88 state is produced in the @xmath475 $ ] channel . now , the highly excited states can appear in this channel . they are pseudoscalar ones corresponding to even values of @xmath272 ( scalar states are not produced by the conserved current @xmath476 ) . moreover , with nonvanishing @xmath477}$ ] the amplitude of transition to scalar @xmath478 $ ] states ( odd @xmath479 ) is not proportional to @xmath480 . thus , near the threshold ( [ thres ] ) the exclusive width of decay into the pair of the pseudoscalar @xmath475 $ ] and the scalar @xmath478 $ ] is singular because the factor @xmath481 in the phase space that explode at thresholds . therefore , exactly at threshold , @xmath482 is infinite . it goes without saying that it can not coincide with the smooth ope prediction near the threshold . these spikes are clearly visible on the plots of ref . @xcite . to maximize the exclusive width @xmath482 for the decay @xmath483_n + [ q{\bar q_{sp}}]_k$ ] near the threshold ( [ thres ] ) we choose the range of @xmath484}$ ] and @xmath485}$ ] close to the corresponding partonic configuration . in terms of partons we deal with the decay @xmath486 . if we fix the square of the effective mass of @xmath487 pair @xmath488 then the momentum of the light @xmath50 is @xmath489 . for hadrons @xmath490}$ ] close to @xmath488 and the characteristic hadronic mass squared in @xmath491 system is @xmath492}\sim \beta(m_q^2 -m^2 _ { \psi { \bar \psi}})/m_q$ ] . then , it is simple to check that the threshold range is @xmath493 } \sim \beta\;,\;\;\;\ ; m_k^{[q{\bar q_{sp } } ] } \sim \beta\;.\ ] ] thus , it is just a few first scalar excitations in @xmath494 system that are relevant . if @xmath484}$ ] and @xmath485}$ ] fall outside the kinematics indicated above then the exclusive width @xmath482 is additionally suppressed . let us remind that the bulk contribution into the total width is provided by the ground state in the @xmath495 channel and @xmath485}\lesssim \sqrt{m_q\beta}$ ] . what is under discussion is a small tail of highly exited @xmath495 states which determines the oscillating component . the relevant matrix element is @xmath496_n [ q{\bar q_{sp}}]_k| ( { \bar q } \gamma_\mu q ) ( { \bar\psi}\gamma^\mu \psi ) |h_q \rangle= \langle [ \psi{\bar\psi } ] _ n |{\bar\psi}\gamma^\mu \psi|0\rangle \ , \langle [ q{\bar q_{sp}}]_k| { \bar q } \gamma_\mu q|h_q \rangle\ , .\ ] ] it is easy to see that the residue @xmath497_n @xmath498}$ ] , while the transition amplitude @xmath499_k| { \bar q } \gamma_\mu q|h_q \rangle$ ] scales as @xmath500 . assembling all factors together we find that near the threshold @xmath501_n + [ q{\bar q_{sp}}]_k ) \sim g^2 n_c \frac{m_\psi^2 \beta^3}{m_q^3 |{\vec p}\,| } \sim \gamma_q \,\frac{m_\psi^2 \beta^3}{m_q^4 |{\vec p}\,| } \ , .\ ] ] this equation describes both , the singularity at thresholds and deviation from local duality between the thresholds . the spatial momentum @xmath502 is @xmath503}\,(m_{h_q } - m_n^{[\psi { \bar \psi } ] } - m_k^{[q{\bar q}_{sp } ] } ) } \ ; .\ ] ] in the middle between the thresholds in @xmath504 the value of @xmath505 , and @xmath506_n + [ q{\bar q_{sp}}]_k ) \sim \gamma_q \ , \frac{m_\psi^2 \beta^{3/2}}{m_q^{7/2}}\;.\ ] ] this estimate gives the amplitude of the oscillating component . it is applicable also to the threshold spikes provided these spikes are averaged over the intervals of @xmath327 less but comparable with the period of oscillations in @xmath327 dependence ( @xmath507 . therefore , we conclude that the violation of local duality dies off as @xmath508 . this effect is by far the largest duality violating contribution . the occurrence of a relatively weak suppression is due to ( a ) the zero resonance width approximation ; ( b ) the singular nature of the two - body phase space in two dimensions . both features have no parallel in actual qcd . in summary , we identified two leading effects that are responsible for deviations from the parton formula one is associated with the four - fermion operator in ope , appearing due to @xmath442 , the second is the additional duality violating component that was absent at @xmath75 . the first , inclusive one , dies off as @xmath137 , the second ( exclusive ) at least as @xmath508 . we do not see any room for @xmath1 deviations , even oscillating . the situation we encounter in the t hooft model is very instructive . the model is readily treatable , which allows one to advance quite far in constructing the ope series . it is superrenormalizable , thus providing an especially clean environment for testing various subtle aspects of ope . the perturbative series for the coefficient functions in the large @xmath26 limit converges . we find , with satisfaction , that all general statements regarding ope are fully confirmed . the model also clearly exhibits the breaking of local duality by oscillating terms . these oscillations are related to the exponential terms in the euclidian domain and not seen in ope . due to zero meson widths in the large @xmath26 limit they are suppressed only by powers of @xmath1 which we have determined . we note that in the t hooft model the local duality of the ope predictions in the inclusive heavy flavor decays ( both semileptonic and nonleptonic ) holds much better than in @xmath309 , the generally recognized classical laboratory for applications of ope . it is in contrast to the opinion often expressed in the literature that ope is not applicable in the inclusive heavy quark widths . moreover , the numerical computations of ref . @xcite suggest that ope width approaches the ( smeared ) hadronic ones at a few percent level very soon , right after a few first channels are open . in actual qcd , already the first excited states are broad enough and inconspicuous , leave alone high excitations . when a finite resonance width is introduced , it immediately leads to dynamical smearing of the spectral densities , ensuring an exponential suppression of the oscillating duality violating terms ( see sec . [ sub : tau ] and ref . @xcite ) . thus , in terms of actual qcd we are still very far from the solution of this extremely important problem ; the exercise performed gives us some kind of an upper bound . as previously , in actual qcd , we have to rely on models while estimating the exponential / oscillating terms not seen in ope . the choice is not large only two models were suggested previously . one of them is an instanton - based model @xcite , another is a resonance - based model @xcite , close in spirit to estimates we have presented above . the instanton - based model is simple and predictive , but it apparently lacks the sophistication inherent to the phenomenon in actuality . in particular , it predicts an oscillating component @xmath509 , rather than @xmath510 as would be natural from the resonance point of view . thus , the t hooft model teaches us that the instanton - based estimates can not be fully true . on the other hand , the resonance - based model , which works satisfactorily in the limit of infinitely narrow resonances , does not give a full answer as to how strongly the oscillating component is suppressed when the finite resonance widths are switched on . it is clear that further steps in developing the existing or engineering new models are needed . this work presents the first estimate of the duality violations , from the resonance - related considerations based on a @xmath511 expansion , in the practically important problem of the hadronic @xmath37 decays . although not fully conclusive , the results are very encouraging , and call for expansion of these ideas in other processes . this is an obvious task for the future . k. wilson , _ phys . rev . _ * 179 * ( 1969 ) 1499 ; in proc . 1971 int . symp . on electron and photon interactions at high energies , n. mistry , ed . ( new york , 1972 ) , p. 115 ; + k. wilson and j. kogut , _ phys . reports _ * 12 * ( 1974 ) 75 ; + wilson s ideas were adapted to qcd in ref . @xcite . m. shifman , _ theory of preasymptotic effects in weak inclusive decays _ , in proc . workshop on _ continuous advances in qcd _ a. smilga ( world scientific , singapore , 1994 ) , page 249 [ hep - ph/9405246 ] ; _ recent progress in the heavy quark theory _ , in _ particles , strings and cosmology _ , proc . pascos-95 , ed . j. bagger _ ( world scientific , singapore , 1996 ) , page 69 [ hep - ph/9505289 ] ; + see also ref . @xcite . g. t hooft , _ nucl . _ * b75 * ( 1974 ) 461 [ reprinted in g. t hooft , _ under the spell of the gauge principle _ ( world scientific , singapore 1994 ) , page 443 ] ; see also ref . @xcite for a discussion of subtleties in the regularization of the t hooft model . c. callan , n. coote , and d. gross , _ phys . * d13 * ( 1976 ) 1649 ; + m. einhorn , _ phys . _ * d14 * ( 1976 ) 3451 ; + m. einhorn , s. nussinov , and e. rabinovici , _ phys . rev . _ * d15 * ( 1977 ) 2282 ; + i. bars and m. green , _ phys . rev . _ * d17 * ( 1978 ) 537 .

the t hooft model ( two - dimensional qcd in the limit of large number of colors ) is used as a laboratory for exploring various aspects of the heavy quark expansions in the nonleptonic and semileptonic decays of heavy flavors . we perform a complete operator analysis and construct the operator product expansion ( ope ) up to terms @xmath0 , inclusively . the ope - based predictions for the inclusive widths are then confronted with the phenomenological " results , obtained by summation of all open exclusive decay channels , one by one . the summation is carried out analytically , by virtue of the t hooft equation . the two alternative expressions for the total widths match . we comment on the recent claim in the literature of a @xmath1 correction to the total width which would be in clear conflict with the ope result . the issue of duality violations both in the simplified setting of the t hooft model and in actual qcd is discussed . the amplitude of oscillating terms is estimated .

let us consider a classical spin-1/2 ising system with nearest - neighbor ferromagnetic interactions , in the presence of an external magnetic field @xmath2 , on a finite @xmath1-dimensional lattice of @xmath3 sites . the partition function can be written as @xmath4 . \label{isipf}\ ] ] here @xmath5 denotes an ising spin variable associated to the site @xmath6 of the lattice . the first sum extends to all configurations of the spins , the second to all distinct pairs @xmath7 of nearest - neighbor spins , the third to all spins . we have set @xmath8 , with @xmath9 the temperature , @xmath10 the exchange coupling of the spins , @xmath11 the boltzmann constant , and @xmath12 the reduced magnetic field . it is a classical result@xcite that , for real @xmath9 , @xmath13 has a sequence of zeroes that can occur only on the imaginary axis of the complex @xmath14 plane . this statement remains true for a wide variety of models with ferromagnetic couplings , including ising models of arbitrary spin@xcite , @xmath15-vector models@xcite ( at least for @xmath16 ) , etc .. as long as the number @xmath3 of sites remains finite , these zeroes give rise to a sequence of logarithmic branch - points of the free energy . for @xmath9 above its critical value @xmath17 , when the thermodynamic limit @xmath18 is taken , these cuts coalesce into two continuous lines of singularities along the imaginary axis of the @xmath19-plane that extend to infinity and originate at the `` yang - lee(yl ) edges '' , @xmath20 , with @xmath21 . the partition function must then be nonzero and the free energy must be analytic in a strip containing the real axis of the complex reduced field plane , so that no phase transition can occur for @xmath22 . as @xmath23 , we have @xmath24 , so the gap between the endpoints of the singularity lines shrinks and they tend to pinch the real axis of the complex field plane giving rise , for @xmath25 , to the characteristic discontinuity associated with the spontaneous magnetization . at fixed @xmath26 , in the vicinity of a yl edge , the magnetization per spin is expected to exhibit a power - law behavior@xcite @xmath27 controlled by an exponent @xmath28 . the main features of these yl edge - singularities have been extensively studied . _ a priori _ the exponent @xmath28 might depend on the temperature and the particular features of the model , however it was observed that it is universal , i.e. it depends only on the spatial dimensionality , but not on the structure of the lattice on which the spin model is defined . moreover , due to the presence of the magnetic field , this exponent does not depend on the number of components of the spin . hence for an @xmath15-vector ferromagnetic system , it must be the same as for an ising system . finally , the study of solvable models in one dimension or for @xmath29 ( the mean - field model ) or , for any dimension , in the @xmath30 limit ( the spherical model ) , and finally the numerical study@xcite of non - trivial ising systems in @xmath31 and @xmath32 dimensions , indicates that , for @xmath33 , the exponents @xmath34 are temperature - independent . due to these universality features , the properties of the yl edges have been related@xcite to those of the ordinary critical points in the theory of second - order phase transitions . in this respect , an important step forward was to show that a renormalization - group approach to the calculation of the exponent @xmath28 can be formulated@xcite in terms of an effective landau - ginzburg one - component scalar field theory with a cubic interaction and a purely imaginary coupling . this entails the upper critical dimensionality @xmath35 , at and above which the exponent takes its mean - field value @xmath36 . moreover @xmath28 can be expressed as an expansion in powers of @xmath37 , whose coefficients have been so far computed@xcite through the third order . see eq.([sigmaeps ] ) below . the interest of an accurate determination of @xmath38 is enhanced by the realization that the yl edge exponent is also related to other exponents characterizing the behavior of several quite different systems : \a ) the pressure for @xmath1-dimensional fluids , with repulsive - core interactions among their constituents , exhibits an unphysical singularity located at negative values of the activity and showing universal exponents@xcite @xmath39 . a similar property is true for lattice systems of hard squares ( and higher - dimensional solids ) . \b ) the number - per - site of directed branched polymers with @xmath40 bonds ( or of directed site- or bond - animals@xcite of size @xmath40 ) on a @xmath1-dimensional lattice , has a scaling behavior characterized by a power of @xmath40 with universal exponent@xcite @xmath41 . the scaling behavior of the directed branched polymers has been mapped@xcite into that of the aforementioned fluids at the unphysical singularity , in one fewer space dimension . \c ) the universal exponents characterizing the behavior of the number - per - site of large isotropic branched polymers@xcite in a good solvent ( or , equivalently@xcite , of undirected site- or bond - animals ) on a @xmath1-dimensional lattice can be expressed as @xmath42 . the scaling behavior of the isotropically branched polymers has been mapped@xcite into that , mentioned above , of the fluids in two fewer dimensions . \d ) a field theoretic model@xcite of the anderson localization exhibits the same critical behavior as the isotropic branched polymers mentioned above in c ) . refs . [ ] provide us with tables of numerical estimates of these exponents for the systems of a ) , b ) and c ) in spatial dimensionalities @xmath43 , which corroborate these exponent identifications . in particular , estimates of the exponent @xmath44 for high - dimensional undirected site - animals have been obtained from 15th - order activity expansions@xcite , and , more recently , have been complemented by extensive montecarlo simulations@xcite and exact enumerations@xcite . we have recently calculated@xcite , in most cases through 24th order , the high - temperature(ht ) and low - field expansion of the magnetization in an external field for several models in the ising universality class , including the conventional ising spin-1/2 model , on a sequence of bipartite lattices of spatial dimensionalities @xmath45 . in this paper , we shall use these data , most not yet existing in the literature , to improve the accuracy and extend the range of direct estimates of the exponents of the yl edge - singularity . our work is based on the observation@xcite that this task can be accomplished restricting to the study of the ising magnetization in a particular ht limit , since the exponents @xmath38 are temperature - independent . it was shown that , in this limit , for each value of @xmath1 , the bivariate expansion of the magnetization in powers of the inverse temperature at low field reduces to a simpler univariate expansion of a quantity related to the density of a dimer system on the same lattice , in powers of a variable @xmath46 that can be viewed as the activity of the dimers . hence , the estimates of the exponents @xmath38 can be obtained from the simpler study of a singularity in the complex @xmath46-plane . the paper is organized as follows . in the second section , we describe briefly the dimer model and sketch the arguments relating the ising magnetization and the dimer density . in the third section , we discuss the numerical estimates of the exponents @xmath38 . in the fourth section , we briefly mention the possibility of obtaining accurate estimates of the dimer constants from the dimer series for several lattices . in the final section , we summarize our work and draw some conclusions . @xmath47 & 2 & 3 & 4 + @xmath48 & -14 & -33 & -60 + @xmath49 & 116 & 438 & 1096 + @xmath50 & -1042 & -6381 & -22076 + @xmath51 & 9812 & 98298 & 471384 + @xmath52&-95288 & -1571646 & -10462752 + @xmath53&945688 & 25804572 & 238712352 + @xmath54 & -9537906 & -432195261 & -5559491148 + @xmath55 & 97398764 & 7351521882 & 131557495336 + @xmath56 & -1004479624 & -126601633818 & -3152926387520 + @xmath57 & 10442811216 & 2202345302028 & 76350685086240 + @xmath58 & -109291830952&-38634960958878&-1864887612147680 + @xmath59 & 1150263509280&682589371293612&45882795957148336 + @xmath60 & -12164408791920 & -12133302712160964 & -1135919635021757184 + @xmath61 & 129177146454536 & 216812614019536368 & 28273604715543144816 + @xmath62&-1376741271026898 & -3892138971898300893 & -707057878652500074156 + @xmath63&14719835348283940 & 70154203323444808578 & 17755217609022707289048 + @xmath64&-157827022198103624 & -1269064065215177023170 & -447499139067294036693120 + @xmath65&1696509872615736256 & 23030962300401009234828 & 11315759542146218070302592 + @xmath66&-18277500804075889672 & -419178020538794595807786 & -286983128267601041433972576 + @xmath67&197318358676755340504 & 7649309116068955304095452 & 7297713321539491454122083408 + @xmath68&-2134157389758234716560 & -139919791900565246008916796 & -186023844148307269386048046560 + @xmath69&23121845343883130936248&2564949986696274806668222464 & 4752360937807056276521029006800 + @xmath70&-250895842743288634987656&-47113178583259985664916986702 & -121654579352079670288510647161952 + [ tab1 ] @xmath71 & 4 & 8 + @xmath72 & -60 & -248 + @xmath73 & 1096 & 9488 + @xmath74 & -22100 & -403528 + @xmath75 & 473064 & 18295568 + @xmath76 & -10540512 & -865807424 + @xmath77 & 241719216 & 42249956512 + @xmath78 & -5664784788 & -2109836426376 + @xmath79&135024044344 & 107268694276016 + @xmath56 & -3262426210400 & -5532784189984768 + @xmath57 & 79709668733952 & 288753867270427776 + @xmath58 & -1965728629262720 & -15218580836786546560 + @xmath59 & 48861010499029408 & 808774465817914713216 + @xmath60&-1222763683250863968 & -43288481720615472507456 + @xmath61&30780446257662843696 & 2331290979582407692061408 + @xmath62 & -778830611224069318356 & -126230584983092928283366536 + @xmath63&19796376474243625682760 & 6867529887763685727515233744 + @xmath64 & -505225273989977429147424 & -375209852952369261768265528064 + @xmath65 & 12940687836519051181004448 & 20577462138006148093915106417728 + @xmath66 & -332541786326958137163996960 & -1132370504978616213744537711827968 + @xmath67 & 8570723905802396225090813040 & 62506221601565914680638405721677920 + @xmath68&-221490566192354289867699314976 & -3459983056502070079122589397022126400 + @xmath69 & 5737972822751243066305678738704 & 192014799892871528814114123763838125600 + @xmath70&-148983747147193194624766250874624 & -10681019026724387660511023640151016838528 + [ tab2 ] @xmath71 & 5 & 16 + @xmath80 & -95 & -1008 + @xmath73 & 2210 & 78880 + @xmath81 & -56935 & -6888560 + @xmath82 & 1560470 & 643011936 + @xmath76 & -44589470 & -62772421632 + @xmath77 & 1312933060&6328669301376 + @xmath78 & -39545139015 & -653740982885040 + @xmath79&1212383059070 & 68823661085963680 + @xmath56 & -37702721543530&-7356685696560126848 + @xmath57 & 1186280544459180 & 796252824523662796416 + @xmath58 & -37692235412554270 & -87086303698430880977408 + @xmath59&1207600893566962380 & 9609234910400277365928640 + @xmath60 & -38966834192905441260 & -1068376395044310231082721280 + @xmath61 & 1265202803884630177880 & 119569512978084142014703005120 + @xmath62 & -41303509002873877637895 & -13459302500635793010903317240880 + @xmath63&1354882911889343633812990&1522782576346629681778159256296800 + @xmath64&-44635036629478941618353330&-173070180804086640006367948602645120 + @xmath65&1476101842809890620493385820&19750115971287989745172871861397745920 + @xmath66&-48984496236897026046190228810 & -2262063795052955748647989801450884168960 + @xmath67 & 1630653500450336878870631247220 & 259942605480019278589477461871133106000960 + @xmath68&-54438143496599430247473673703380 & -29961083663149896944399970822493200812776320 + @xmath69 & & 3462835569237061144802332732162000087319991360 + @xmath70 & & -401237452358873371565154489237992019311699297280 + [ tab3 ] @xmath71 & 6 & 32 + @xmath80 & -138 & -4064 + @xmath83 & 3900 & 643136 + @xmath81 & -122310 & -113792032 + @xmath82 & 4086396 & 21547360832 + @xmath84 & -142476792 & -4271044245248 + @xmath85&5122735176 & 874932782274688 + @xmath86&-188517518310 & -183742680108707616 + @xmath87&7064821951140 & 39344571392293056704 + @xmath56 & -268661239644168 & -8557358633880518454784 + @xmath57 & 10340279507701776 & 1885218050259702418922496 + @xmath58 & -402003973427568648 & -419794129141493673828232192 + @xmath59 & 15763048131921626880 & 94331821844075469462840829440 + @xmath60 & -622646937215063631120 & -21363417876150273316847202904320 + @xmath61&24752424038720810997240 & 4871104500436454268454972630464896 + @xmath62 & -989526434040322269780870 & -1117286822866349754715547920533865248 + @xmath63 & 39754803422947748576043180 & 257621581517072116407677681638058301760 + @xmath64 & -1604239977818820429337772040 & -59680091386808879450249399896382705283584 + @xmath65&64993232282038522127491654560 & 13883370669662028006386373064762884655595776 + @xmath66&-2642511808864143082376138558280 & -3241891787443021814766940463936149652806538752 + @xmath67&107788019222920474225378253424840 & 759601317388101093048127502735990937113754258304 + @xmath68 & & -178534783824842834362110547423593615649270807425280 + @xmath69 & & 42081725576331603416392306775511862130364642844236928 + @xmath70 & & -9944795581281129212782166232032493020106438172525218816 + [ tab4 ] @xmath88 & 7 & 64 + @xmath72 & -189 & -16320 + @xmath73 & 6286 & 5193856 + @xmath74 & -232337 & -1849727936 + @xmath75 & 9156882 & 705432330624 + @xmath76&-376866798&-281737586952192 + @xmath77 & 16002790188 & 116325399366292992 + @xmath78 & -695763137601 & -49250328402750744768 + @xmath79&30814814722594 & 21265341161536087474816 + @xmath56 & -1385226427142474&-9328024156759223705208320 + @xmath57 & 63037109428097196 & 4145112005630262044731153920 + @xmath58&-2898142120281195662 & -1862040622714788094682263408640 + @xmath59 & 134406753861096711820 & 844180535052646908871372654226176 + @xmath60 & -6280176867758451284340&-385755924146309028765643631630290940 + @xmath61 & 295357093420022257715616&177488316175328670895488110020974226176 + @xmath62&-13970161606657482586444833 & -82155985773613044917541164342517378676416 + @xmath63&664121988815559152932012890 & 38231156319654300832459678139949723942242688 + @xmath64 & -31713748014463596772472407794 & -17875202142357193337368185100702670312872235520 + @xmath65 & 1520542773828098297725351871436 & 8393167978080707171882156986310088446859172518912 + @xmath66&-73169317004302689750290322402042 & -3956035371299664049518526770009878297187847196261376 + @xmath67 & & 1871101505460166042039514382404078383796375971968146688 + @xmath68 & & -887773576351504314786611216702175344355035369163473610240 + @xmath69 & & 422432182192613348318985610505592297395940532680091395006720 + @xmath70 & & -201538729427533378265902478728701415730702344267711209153902592 + [ tab5 ] the hard dimer model in two space dimensions was introduced@xcite long ago to study the adsorption of diatomic molecules on a regular surface . on a @xmath1-dimensional lattice of @xmath3 sites it describes an assembly of linear objects each one covering a single bond of the lattice including the two endpoint sites , under the constraint of no partial or total overlap ( _ hard _ dimers ) . the statistics of this model is described by the configurational macrocanonical partition function @xmath89 here @xmath90 denotes the number of ways of placing @xmath40 dimers over the links of the @xmath3-site lattice , and @xmath46 is the dimer activity . in the thermodynamical limit @xmath91^{1/n } = 1 + \sum_{s=1}^{\infty } g(s)z^s \label{mdmpf}\ ] ] and the macrocanonical potential is defined as @xmath92 the dimer density per site @xmath93 is then expressed in terms of the potential @xmath94 as @xmath95 with @xmath96 . let us now summarize the simple argument@xcite relating the ht and low - field expansions of the spin-1/2 ising model in the limit of infinite temperature with the low - density expansions for hard dimers on the same lattice . in the thermodynamical limit , the ht expansion of the ising magnetization per spin can be written as @xmath97 with @xmath98 and @xmath99 . in the elementary graphical representation of the ht and low - field expansion of the specific free energy , each term of order @xmath100 in @xmath101 and @xmath102 in @xmath103 is associated to a configuration of @xmath100 bonds and @xmath104 marked vertices on the lattice . the coefficients surviving in the particular limit in which @xmath105 and @xmath106 with fixed @xmath107 , are associated to configurations of @xmath100 separated bonds whose endpoints are @xmath108 marked vertices and therefore they are related to the number of ways of placing @xmath100 hard dimers on the lattice in such a way that for the magnetization ( i.e. the field - derivative of the free energy ) one has @xmath109 \label{isirho}\ ] ] with @xmath110 the activity expansion of the dimer density . the behavior eq.([magn ] ) of the magnetization nearby the yl edge must translate into @xmath111 for the dimer density , where @xmath112 is a real negative quantity . our recent calculation@xcite , in most cases through order 24 , of the ht expansion of the spin-1/2 ising magnetization in the presence of an external field , for several bipartite lattices of dimensionality @xmath0 , enables us to extend through the same order the expansions of the dimer density in powers of the activity @xmath46 on these lattices . such expansions were already tabulated in the literature@xcite in the case of the square(sq)(17 terms ) , the simple - cubic(sc)(15 terms ) , the body - centered - cubic(bcc)(13 terms ) lattices . the known coefficients are reproduced by our calculation . actually , a few more coefficients could be derived from the published ht and low - field expansions@xcite for the sq(19 terms ) and the sc(17 terms ) lattices . also for the hyper - simple - cubic(h4sc ) lattice in @xmath113 spatial dimensions , 16 correct terms of the free - energy expansion were tabulated@xcite in the same paper . however , these data were overlooked in ref . [ ] and in the successive work . we have extended the activity expansions in the case of the h4sc and the hyper - bcc ( h4bcc ) lattices in @xmath113 spatial dimensions through the 24th order . our calculation for the higher - dimensional hyper - bcc lattices extends also through the 24th order , whereas in the case of the five- and six - dimensional hsc lattices , it reaches only the 22nd and the 21st , respectively . for dimension @xmath114 , our expansion on the hsc lattice extend only to the 20th order . these data were not yet available in the literature . the expansions for the h5sc , h6sc, ... ,h7sc lattices have been truncated at a slightly smaller order , because on the ( hyper-)cubic lattices the computation of the embedding numbers for the highest - order graphs is too time - consuming to be completed in just a few days by a single personal computer . while in the case of the hbcc lattices the computational complexity of the calculation is independent@xcite of the lattice dimensionality , in the hsc case it grows exponentially with the space dimensionality . we have not yet extended the calculation of the series in the cases of non - bipartite lattices such as the triangular , face - centered - cubic and their high - dimensional generalizations . the coefficients of our extended expansions of the dimer density series for @xmath115 are reported in the tables [ tab1 ] ... [ tab5 ] . for the dimer density series , we have located the nearest negative singularity in the complex @xmath46-plane and estimated its exponent @xmath28 by the numerical tools currently used to extrapolate the behavior of power expansions to the border of their analyticity disk , in particular employing the _ differential approximants _ ( das ) . these are a generalization of the well known pad approximant(pa ) method that approximates the series under study by the solution of an ordinary inhomogeneous linear differential equation with polynomial coefficients . for a detailed illustration of their definitions , of their properties , and for a general discussion of the uncertainties in the estimates of the singularity parameters determined by this method , we address the reader to refs . let us first consider the few known terms of the @xmath116-expansion of the exponent @xmath28 @xmath117 where @xmath118 denotes the riemann zeta function . the expansion eq.([sigmaeps ] ) can be resummed following various procedures , all yielding consistent results for @xmath119 . for example , several simple continuous interpolations of @xmath38 with respect to the space dimensionality @xmath1 , can be found@xcite in the literature , which are obtained from low - order constrained pad approximants . the continuous curve in fig.[figura_edge ] , is the plot vs @xmath1 of a [ 3/2 ] pad approximant formed from the @xmath116-expansion eq.([sigmaeps ] ) , that satisfies the additional constraints of reproducing the known exact values@xcite @xmath120 for @xmath31 and @xmath121 at the lower critical dimension @xmath122 . for @xmath123 , the exponent should retain the value @xmath124 and so this part of the curve is drawn flat . the constrained [ 3/2 ] pa has the expression @xmath125 the resummation by this approximant is visually indistinguishable from that obtained by the [ 6/0 ] pa subject to the constraint of reproducing the exact results for @xmath126 . the latter approximation was proposed in ref . [ ] to describe the behavior of the exponents of the unphysical singularity at negative activity for repulsive - core fluids as @xmath1 varies . alternative , but completely consistent interpolations can be obtained by other more refined resummation procedures@xcite , including a pad - borel method and a conformal mapping technique . for each dimension @xmath1 , the small spread among the estimates of @xmath38 obtained by the various resummations methods of the expansion eq.([sigmaeps ] ) can be used to roughly limit an interval of possible values of @xmath38 , whose width increases with @xmath116 . we have reported these spreads in the eighth column of table [ tab6 ] . an @xmath116-expansion through the third order has been computed@xcite also for the leading correction - to - scaling exponent @xmath127 . its values @xmath128 , @xmath129 , @xmath130 and @xmath131 for the various dimensions have been estimated@xcite by constrained pas . here we shall use these estimates without further discussion . from these studies of the @xmath116-expansion , we are thus led to expect that the exponent @xmath38 should lie between @xmath132 , its @xmath122 value , and @xmath36 , the @xmath133 value . for intermediate values of @xmath1 , the exponent should take values not far from those suggested by the various resummation procedures . in conclusion , @xmath38 is expected to take small and possibly positive values for @xmath134 . the das are probably unable to measure accurately exponents in this range of values and therefore , as suggested in ref . [ ] , it is more convenient to analyze the @xmath46-derivative of the dimer density , rather than @xmath93 itself , because it has a sharper singularity , characterized by the exponent @xmath135 . . estimates of the location @xmath136 and the exponent @xmath38 of the nearest singularity of the dimer density in the complex activity plane @xmath46 for several bipartite lattices of dimension @xmath137 . in the first column , we have indicated the structure and dimensionality of the lattice . the second and fourth column show the results of ref . [ ] , while the third and fifth contain the results of this paper . notice that , for @xmath138 , our estimates for the hsc lattices are based on shorter series . in the sixth column , we have reported the values of @xmath139 obtained@xcite from the exponent occurring for repulsive - core fluids . in the seventh column , we have shown estimates@xcite of the exponent @xmath140 derived from a high - precision montecarlo simulation of site - animals . in the eighth column , we have indicated ranges of estimates of @xmath28 obtained from different resummation prescriptions of the @xmath116-expansion . the last column reports exact results for @xmath28 , whenever known . the data in the last two columns depend only on the lattice dimensionality . [ cols="^,^,^,^,^,^,^,^,^",options="header " , ] [ tab7 ] in terms of the new variable , the potential @xmath94 can be , with a better approximation , continued by pas into a larger region of the complex @xmath46-plane , encompassing intermediate values of @xmath46 such as @xmath141 . we have tried to infer the large @xmath46 limit of the quantity @xmath142 in eq.([tilde_h ] ) by observing that , in the intermediate @xmath46 region , this quantity behaves linearly in @xmath143 to a fair approximation , and extrapolating this behavior to @xmath144 . we can thus conjecture estimates of the constants @xmath145 , that although generally reasonable and consistent with the known@xcite bounds , unsurprisingly show an accuracy much lower than in the @xmath146 case and therefore will not be reported in the table [ tab7 ] . the blame for this failure lays on the still insufficient extension of the region of accurate analytic continuation and the arbitrariness of the various extrapolation procedures , that make a safe evaluation of the uncertainties difficult . we have derived the coefficients of the series expansions of the dimer density in powers of the activity , in most cases through 24th - order , for several bipartite lattices of dimensionality @xmath147 . thus we have not only extended the existing series data , so far published only for @xmath148 , but also produced series for @xmath149 . an analysis of this set of data improves the accuracy in the determination of the locations and the exponents of the nearest real negative singularity of the dimer density in the complex activity plane . the exponents controlling the yang - lee edge - singularity of this class of ferromagnetic spin models in a wide range of space dimensions are related , in some cases by a simple dimensionality shift , with the exponents characterizing very different systems . the numerical estimates presently available for all these exponents show a good consistency among them and with the results of appropriate resummations of the renormalization - group @xmath116-expansion . our dimer - density series are also shown to be of some use in estimating the dimer constants @xmath150 and @xmath145 . we are grateful to a.j . guttmann for reading a preliminary draft . we are also grateful to p.h.lundow and k. markstrm for helpful comments on the final section of the paper . we thank the physics departments of milano - bicocca university and of milano university for hospitality and support . partial support by the miur is also acknowledged . estimates ( full circles ) of the edge - exponent @xmath38 , obtained our dimer density expansions vs the lattice dimensionality . the continuous curve is obtained resumming the third order @xmath116-expansion of @xmath38 by a [ 3/2 ] pad approximant constrained to reproduce the exactly known values of the exponent for @xmath122 and @xmath31 . , width=3 ] f. dunlop and c. m. newman , commun . * 44 * , 223 ( 1975 ) . c. m. newman , j. stat . phys . * 15 * , 399 ( 1976 ) . e. h. lieb and a. d. sokal , commun . phys . * 80 * , 153 ( 1981 ) . kortman and r.b . griffiths , phys . rev . lett . * 27 * , 1439 ( 1971 ) . fisher , phys . lett . * 40 * , 1610 ( 1978 ) . de alcantara bonfin , j.e . kirkham and a.j . mckane , j.phys . a * 14 * , 2391 ( 1981 ) . d. poland , j. stat . phys . * 35 * , 341 ( 1984 ) . a. baram and m. luban , phys . a * 36 * , 760 ( 1987 ) . s.n . lai and m.e . fisher , j. chem . 103 * , 8144 ( 1995 ) . y. park and m.e . fisher , phys . e * 60 * , 6323 ( 1999 ) . d. stauffer and a. aharony , _ `` introduction to percolation theory '' _ , 2nd edition , ( taylor and francis , london 1994 ) . guttmann , in _ `` polygons , polyominoes and polycubes '' _ , edited by a.j . guttmann lecture notes in physics , vol . 775 , ( springer new york , 2009 ) . cardy , j. phys . a * 15 * , l593 ( 1982 ) . stanley , s.redner and z.r . yang , j.phys . a * 15 * , l569 ( 1982 ) . n. breuer and h. k. janssen , z. phys . b * 48 * , 347 ( 1982 ) . j.z . imbrie , j. phys . a * 37 * , l137 ( 2004 ) . g. parisi and n. sourlas , phys . lett . * 46 * , 871 ( 1981 ) . t.c.lubensky and j. isaacson , phys . 41 * , 829 ( 1978 ) . d.c . brydges and j.z . imbrie , j. stat . phys . * 110 * , 503 ( 2003 ) . t.c.lubensky and a. mc kane , j. physique ( france ) lett . * 42 * , l331 ( 1981 ) . j. adler , y. meir , a. b. harris , a. aharony and j.a.m.s . duart , phys . b * 38 * , 4941 ( 1988 ) . hsu , w. nadier and p. grassberger , j. phys . a * 38 * , 775 ( 2005 ) . s. luther and s. mertens , j. stat . p09026 ( 2011 ) . p. butera and m. pernici , phys . b * 83 * , 054433 ( 2011 ) . p. butera and m. pernici , phys . e * 85 * , 021105 ( 2012 ) . d.s . gaunt , phys . rev . * 179 * , 174 ( 1969 ) . baker jr . and p. moussa , j. appl . phys . * 49 * , 1360 ( 1978 ) . d.a . kurtze and m.e . fisher , phys . b * 20 * , 2785 ( 1979 ) . r. h. fowler and g. s. rushbrooke , trans . faraday soc . * 33 * , 1272 ( 1937 ) . o.j . heilmann and e.h . lieb , commun . phys . * 25 * , 190 ( 1972 ) . c. gruber and h. kunz , commun . * 22 * , 133 ( 1971 ) . s. mckenzie , can . j. phys . , * 57 * , 1239 ( 1979 ) . guttmann , in _ `` phase transitions and critical phenomena '' _ edited by c. domb and j. l. lebowitz , vol . 13 , page 1 , ( academic press , new york 1989 ) . cardy , phys . lett . * 54 * , 1354 ( 1985 ) . roskies , phys . b * 23 * , 6037 ( 1981 ) . ruiz - lorenzo , j. phys . a * 31 * , 8773 ( 1998 ) . c. ferber , d. foster , h. p. hsu and r. kenna , eur . j. b * 83 * , 245 ( 2011 ) . s. r. finch , _ mathematical constants _ , cambridge university press ( 2003 ) . kasteleyn , physica * 27 * , 1209 ( 1961 ) . h. n. v. temperley and m.e . fisher , phil . mag . * 6 * , 1061 ( 1961 ) . fisher , phys . * 124 * , 1664 ( 1961 ) . baxter , j. math . phys . * 9 * , 650 ( 1968 ) . s. friedland and u.n . peled , adv . appl . math . * 34 * , 486 ( 2005 ) . l. k. runnels , j. math . * 11 * , 842 ( 1970 ) . i. beichl , d.p . oleary , and f. sullivan , phys . e * 64 * , 016701 ( 2001 ) . j. f. nagle , phys . rev . * 152 * , 190 ( 1966 ) . y. kong , phys . e * 74 * , 061102 ( 2006 ) . yan huo , heng liang , si - qi liu , and fengshan bai , phys . e * 77 * , 016706 ( 2008 ) . s. friedland , e. krop , p.h . lundow and k. markstrm , j. stat . phys . * 133 * , 513 ( 2008 ) .

we have extended , in most cases through 24th order , the series expansions of the dimer density in powers of the activity in the case of bipartite ( ( hyper)-simple - cubic and ( hyper)-body - centered - cubic ) lattices of dimensionalities @xmath0 . a numerical analysis of these data yields estimates of the exponents characterizing the yang - lee edge - singularities for lattice ferromagnetic spin - models as @xmath1 varies between the lower and the upper critical dimensionalities . our results are consistent with , but more extensive and sometimes more accurate than those obtained from the existing dimer series or from the estimates of related exponents for lattice animals , branched polymers and fluids . we mention also that it is possible to obtain estimates of the dimer constants from our series for the various lattices .

Simon Monjack's Cause of Death: 'Just Like Brittany' Email This The Los Angeles County Coroner's Office has determined that Simon Monjack died from acute pneumonia and severe anemia, which eerily are the same two conditions that caused the death of his wife, Brittany Murphy, late last year. Monjack, a British screenwriter, was found dead May 23 at the couple's Hollywood home by his mother-in-law. Coroner Assistant Chief Ed Winter told CNN that Monjack's cause of death was "just like Brittany" and that some prescription drugs were found in his system, but not enough to have contributed to his death. No illegal drugs were found. The Los Angeles County Coroner's Office has determined that Simon Monjack died from acute pneumonia and severe anemia, which eerily are the same two conditions that caused the death of his wife, Brittany Murphy, late last year.Monjack, a British screenwriter, was found dead May 23 at the couple's Hollywood home by his mother-in-law. Coroner Assistant Chief Ed Winter told CNN that Monjack's cause of death was "just like Brittany" and that some prescription drugs were found in his system, but not enough to have contributed to his death.No illegal drugs were found. http://xml.channel.aol.com/xmlpublisher/fetch.v2.xml?option=expand_relative_urls&dataUrlNodes=uiConfig,feedConfig,entry&id=822833&pid=822832&uts=1273241316 http://www.popeater.com/mm_track/popeater/movies/?s_channel=us.moviespop&s_account=aolpopeater,aolsvc&omni=1&ke=1 http://cdn.channel.aol.com/cs_feed_v1_6/csfeedwrapper.swf Recently Departed Celebrities Lynn Redgrave, May 2: The third member of the Redgrave acting dynasty to die in a year, Lynn passed away at her Manhattan apartment at age 67 of as-yet unannounced causes. The 'Georgy Girl' star's niece, Natasha Richardson, died a year ago and her older brother Corin, succumbed to illness a month ago. Teresa Barbieri, Getty Images Teresa Barbieri, Getty Images Recently Departed Celebs Sharon Murphy, Brittany's mother, spoke out after the results were released."I am still in shock and mourning over the deaths of my daughter Brittany and son-in-law Simon," Sharon said in a statement (via TMZ ). "It is with great relief that Simon's preliminary autopsy findings have been released, so the media speculations can stop... As I was sure of, just like my daughter Brittany, there was no kind of drug overdose."On May 27, Monjack was laid to rest beside his wife at Forest Lawn Memorial Park in Los Angeles.Murphy was found dead Dec. 20 in her bathroom by Monjack. The final coroner's report, released Feb. 23, stated that she had "elevated levels" of Vicodin and drugs from over-the-counter cold medicine in her system, but no illegal substances. The office concluded Murphy's death was accidental, but likely preventable. She was 32.Following his wife's passing, Monjack's physical and mental health declined sharply.In January, Monjack admitted on 'The Today Show' that he had suffered a minor heart attack just weeks before Murphy died.According to his spokesman, Monjack was due for a heart bypass. "Simon needed a [heart] bypass. I was told he needed a bypass, and I said to him, 'Simon, you have so much going on, let's keep you healthy.' I said, 'You want to be healthy. Don't you?' He said yes, but he said, 'The bypass can wait.'"While the physical health issues were present, his rep said Monjack also died from a "broken heart." In January, Monjack spoke about how Murphy's death turned his life upside down. "My world was destroyed yesterday," he told Access Hollywood.Monjack -- who penned and produced 2006's 'Factory Girl' -- wed Murphy in 2007 in a small, private ceremony at their house. The marriage seemed to come out of nowhere, as the couple never announced their engagement and hardly ever made public appearances together. ||||| Brittany Murphy, Husband's Deaths -- the Mold Factor Brittany Murphy, Husband's Deaths -- the Mold Factor The investigation into Brittany Murphy and's deaths is now being handled by the Los Angeles County Department of Public Health, TMZ has learned ... and it's all because of mold found in their home.Law enforcement sources tell TMZ the issue of mold in the house came up early during the investigation into Brittany's death -- but it was deemed "not to be a contributing factor."Then when Simon passed away a few months later, we're told the issue came up again -- but Brittany's mom, Sharon, wouldn't let the L.A. County Coroner's Office in to investigate the mold. Now, we're told, Sharon has agreed to let Public Health investigators into the home.Mold could be relevant to Simon and Brittany's respiratory health. Pneumonia was a cause of death for both of them.We're also told Simon's mother, Linda Monjack is fully supportive of this move, and will be flying from Europe so she can be close to the investigation.: A rep for Sharon tells TMZ, "I have never been personally asked by the Coroner or anyone from the Health Department to come and inspect my home for mold ... to the best of my knowledge there has been no evidence of mold at the Murphy residence."

– It was eerie enough when Simon Monjack died just a few months after his wife, Brittany Murphy—it was even eerier when it was reported he died of the exact same cause, pneumonia. Now officials believe mold in their home may have contributed to their deaths, law enforcement sources tell TMZ. The investigation has been turned over to the Department of Public Health now that Murphy’s mother has agreed to let them into the home. Click here to read more about Monjack’s cause of death.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Agricultural Work Force Stability and Protection Act''. SEC. 2. CONSIDERATIONS IN THE APPROVAL OF H-2A PETITIONS. Section 218(a) (8 U.S.C. 1188(a)) of the Immigration and Nationality Act is amended-- (1) by redesignating paragraph (2) as paragraph (3); and (2) by inserting after paragraph (1) the following: ``(2) In considering an employer's petition for admission of H-2A aliens, the Attorney General shall consider the certification decision of the Secretary of Labor and shall consider any countervailing evidence submitted by the employer with respect to the nonavailability of United States workers and the employer's compliance with the requirements of this section, and may consult with the Secretary of Agriculture.''. SEC. 3. CONDITION FOR DENIAL OF LABOR CERTIFICATION. Section 218(b)(4) (8 U.S.C. 1188(b)(4)) of the Immigration and Nationality Act is amended to read as follows: ``(4) Determination by the secretary.--The Secretary determines that the employer has not filed a job offer for the position to be filled by the alien with the appropriate local office of the State employment security agency having jurisdiction over the area of intended employment, or with the State office of such an agency if the alien will be employed in an area within the jurisdiction of more than one local office of such an agency, which meets the criteria of paragraph (5). ``(5) Required terms and conditions of employment.--The Secretary determines that the employer's job offer does not meet one or more of the following criteria: ``(A) Required rate of pay.--The employer has offered to pay H-2A aliens and all other workers in the occupation in the area of intended employment an adverse effect wage rate of not less than the median rate of pay for similarly employed workers in the area of intended employment. ``(B) Provision of housing.-- ``(i) In general.--The employer has offered to provide housing to H-2A aliens and those workers not reasonably able to return to their residence within the same day, without charge to the worker. The employer may, at the employer's option, provide housing meeting applicable Federal standards for temporary labor camps, or provide rental or public accommodation type housing which meets applicable local or state standards for such housing. ``(ii) Housing allowance as alternative.-- In lieu of offering the housing required in clause (i), the employer may provide a reasonable housing allowance to workers not reasonably able to return to their place of residence within the same day, but only if the Secretary determines that housing is reasonably available within the approximate area of employment. An employer who offers a housing allowance pursuant to this subparagraph shall not be deemed to be a housing provider under section 203 of the Migrant and Seasonal Agricultural Worker Protection Act (29 U.S.C. 1823) merely by virtue of providing such housing allowance. ``(iii) Special housing standards for short duration employment.-- The Secretary shall promulgate special regulations permitting the provision of short-term temporary housing for workers employed in occupations in which employment is expected to last 40 days or less. ``(iv) Transitional period for provision of special housing standards in other employment.--For a period of five years after the date of enactment of this section, the Secretary shall approve the provision of housing meeting the standards described in clause (iii) in occupations expected to last longer than 40 days in areas where available housing meeting the criteria described in subparagraph (i) is found to be insufficient. ``(v) Preemption of state and local standards.--The standards described in clauses (ii) and (iii) shall preempt any State and local standards governing the provision of temporary housing to agricultural workers. ``(C) Reimbursement of transportation costs.--The employer has offered to reimburse H-2A aliens and workers recruited from beyond normal commuting distance the most economical common carrier transportation charge and reasonable subsistence from the place from which the worker comes to work for the employer, (but not more than the most economical common carrier transportation charge from the worker's normal place of residence) if the worker completes 50 percent of the anticipated period of employment. If the worker recruited from beyond normal commuting distance completes the period of employment, the employer will provide or pay for the worker's transportation and reasonable subsistence to the worker's next place of employment, or to the worker's normal place of residence, whichever is less. ``(D) Guarantee of employment.--The employer has offered to guarantee the worker employment for at least three-fourths of the workdays of the employer's actual period of employment in the occupation. Workers who abandon their employment or are terminated for cause shall forfeit this guarantee. ``(6) Preference for united states workers.--The employer has not assured on the application that the employer will provide employment to all qualified United States workers who apply to the employer and assure that they will be available at the time and place needed until the time the employer's foreign workers depart for the employer's place of employment (but not sooner than 5 days before the date workers are needed), and will give preference in employment to United States workers who are immediately available to fill job opportunities that become available after the date work in the occupation begins.''. SEC. 4. SPECIAL RULES APPLICABLE TO THE ISSUANCE OF LABOR CERTIFICATIONS. Section 218(c) (8 U.S.C. 1188(c)) of the Immigration and Nationality Act is amended to read as follows: ``(c) Special Rules Applicable to the Issuance of Labor Certifications.--The following rules shall apply to the issuance of labor certifications by the Secretary under this section: ``(1) Deadline for filing applications.--The Secretary may not require that the application be filed more than 40 days before the first date the employer requires the labor or services of the H-2A worker. ``(2) Notice within seven days of deficiencies.-- ``(A) The employer shall be notified in writing within seven calendar days of the date of filing, if the application does not meet the criteria described in subsection (b) for approval. ``(B) If the application does not meet such criteria, the notice shall specify the specific deficiencies of the application and the Secretary shall provide an opportunity for the prompt resubmission of a modified application. ``(3) Issuance of certification.-- ``(A) The Secretary shall provide to the employer, not later than 20 days before the date such labor or services are first required to be performed, the certification described in subsection (a)(1)-- ``(i) with respect to paragraph (a)(1)(A) if the employer's application meets the criteria described in subsection (b), or a statement of the specific reasons why such certification cannot be made, and ``(ii) with respect to subsection (a)(1)(B), to the extent that the employer does not actually have, or has not been provided with the names, addresses and Social Security numbers of workers referred to the employer who are able, willing and qualified and have indicated they will be available at the time and place needed to perform such labor or services on the terms and conditions of the job offer approved by the Secretary. For each worker referred, the Secretary shall also provide the employer with information sufficient to permit the employer to contact the referred worker for the purpose of reconfirming the worker's availability for work at the time and place needed. ``(B) If, at the time the Secretary determines that the employer's job offer meets the criteria described in subsection (b) there are already unfilled job opportunities in the occupation and area of intended employment for which the employer is seeking workers, the Secretary shall provide the certification at the same time the Secretary approves the employer's job offer.''. SEC. 5. EXPEDITED APPEALS OF CERTAIN DETERMINATIONS. Section 218(e) (8 U.S.C 1188(e)) of the Immigration and Nationality Act is amended to read as follows: ``(e) Expedited Appeals of Certain Determinations.--The Secretary shall provide by regulation for an expedited procedure for the review of the nonapproval of an employer's job offer pursuant to subsection (c)(2) and of the denial of certification in whole or in part pursuant to subsection (c)(3) or, at the applicant's request, a de novo administrative hearing respecting the nonapproval or denial.''. SEC. 6. PROCEDURES FOR THE CONSIDERATION OF H-2A PETITIONS. Section 218 of the Immigration and Nationality Act (8 U.S.C. 1188) is amended-- (1) by redesignating subsections (f) through (i) as subsections (g) through (j), respectively; and (2) by adding the following after subsection (e): ``(f) Procedures for the Consideration of H-2A Petitions.--The following procedures shall apply to the consideration of petitions by the Attorney General under this section: ``(1) Expedited processing of petitions.--The Attorney General shall provide an expedited procedure for the adjudication of petitions filed under this section, and the notification of visa-issuing consulates where aliens seeking admission under this section will apply for visas and/or ports of entry where aliens will seek admission under this section within 15 calendar days from the date such petition is filed by the employer. ``(2) Expedited amendments to petitions.--The Attorney General shall provide an expedited procedure for the amendment of petitions to increase the number of workers on or after five days before the employers date of need for the labor or services involved in the petition to replace referred workers whose continued availability for work at the time and place needed under the terms of the approved job offer can not be confirmed and to replace referred workers who fail to report for work on the date of need and replace referred workers who abandon their employment or are terminated for cause, and for which replacement workers are not immediately available pursuant to subsection (b)(6).''. SEC. 7. LIMITATION ON EMPLOYER LIABILITY. Section 218(g) (8 U.S.C. 1188(g)) of the Immigration and Nationality Act is amended-- (1) by redesignating paragraph (2) as paragraph (2)(A); and (2) by inserting after paragraph (2)(A) the following: ``(B) No employer shall be subject to any liability or punishment on the basis of an employment action or practice by such employer that conforms with the terms and conditions of a job offer approved by the Secretary pursuant to this section, unless and until the employer has been notified that such certification has been amended or invalidated by a final order of the Secretary or of a court of competent jurisdiction.''. SEC. 8. LIMITATION ON JUDICIAL REMEDIES. Section 218(h) of the Immigration and Nationality Act (8 U.S.C. 1188(h)) is amended by adding at the end thereof the following: ``(3) No court of the United States shall have jurisdiction to issue any restraining order or temporary or permanent injunction preventing or delaying the issuance by the Secretary of a certification pursuant to this section, or the approval by the Attorney General of a petition to import an alien as an H- 2A worker, or the actual importation of any such alien as an H- 2A worker following such approval by the Attorney General.''.

Agricultural Work Force Stability and Protection Act - Amends the Immigration and Nationality Act with respect to the admission of temporary agricultural (H-2A visa) workers and related labor certification provisions.

SECTION 1. CREDIT TO HOLDERS OF INDIAN TRIBAL PRISON FACILITY BONDS. (a) In General.--Part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 (relating to credits against tax) is amended by adding at the end the following new subpart: ``Subpart H--Nonrefundable Credit for Holders of Indian Tribal Prison Facility Bonds ``Sec. 54. Credit to holders of Indian tribal prison facility bonds. ``SEC. 54. CREDIT TO HOLDERS OF INDIAN TRIBAL PRISON FACILITY BONDS. ``(a) Allowance of Credit.--In the case of a taxpayer who holds an Indian tribal prison facility bond on a credit allowance date of such bond which occurs during the taxable year, there shall be allowed as a credit against the tax imposed by this chapter for such taxable year an amount equal to the sum of the credits determined under subsection (b) with respect to credit allowance dates during such year on which the taxpayer holds such bond. ``(b) Amount of Credit.-- ``(1) In general.--The amount of the credit determined under this subsection with respect to any Indian tribal prison facility bond is the amount equal to the product of-- ``(A) the credit rate determined by the Secretary under paragraph (2) for the month in which such bond was issued, multiplied by ``(B) the face amount of the bond held by the taxpayer on the credit allowance date. ``(2) Determination.--During each calendar month, the Secretary shall determine a credit rate which shall apply to bonds issued during the following calendar month. The credit rate for any month is the percentage which the Secretary estimates will permit the issuance of Indian tribal prison facility bonds without discount and without interest cost to the issuer. ``(c) Limitation Based on Amount of Tax.--The credit allowed under subsection (a) for any taxable year shall not exceed the excess of-- ``(1) the sum of the regular tax liability (as defined in section 26(b)) plus the tax imposed by section 55, over ``(2) the sum of the credits allowable under this part (other than this subpart and subpart C). ``(d) Credit Included in Gross Income.--Gross income includes the amount of the credit allowed to the taxpayer under this section (determined without regard to subsection (c)) and the amount so included shall be treated as interest income. ``(e) Indian Tribal Prison Facility Bond.--For purposes of this part, the term `Indian tribal prison facility bond' means any bond issued as part of an issue if-- ``(1) 95 percent or more of the proceeds of such issue are to be invested in investment grade obligations and the proceeds from such investment are used for the construction, acquisition, rehabilitation, expansion, or operating expanses of a qualified Indian tribal prison facility, ``(2) the bond is issued by the Indian tribe within the jurisdiction of which such facility is located, ``(3) the bond is issued pursuant to a plan developed by the Indian tribe, ``(4) the issuer designates such bond for purposes of this section, ``(5) the term of each bond which is part of such issue does not exceed 10 years, and ``(6) no amount of proceeds of such issue (including proceeds from any investment under paragraph (1)) may be used to pay the costs of issuance to the extent such amount exceeds 2 percent of the sale proceeds of such issue. ``(f) Qualified Indian Tribal Prison Facility.--For purposes of this section, the term `qualified Indian tribal prison facility' means any residential correctional or detention facility located on the qualified Indian land of the issuing Indian tribe substantially all of the inmates of which are adult or juvenile members of such Indian tribe. ``(g) Limitation on Amount of Bonds Designated; Allocation of Bonds.-- ``(1) National limitation.--There is an Indian tribal prison facility bond limitation for each calendar year. Such limitation is-- ``(A) $200,000,000 for 2005, ``(B) $200,000,000 for 2006, ``(C) $200,000,000 for 2007, and ``(D) except as provided in paragraph (3), zero thereafter. ``(2) Allocation of bonds.-- ``(A) In general.--The Secretary, after consultation with the Secretary of the Interior, shall allocate the Indian tribal prison facility bond limitation among those Indian tribes which submit a plan which contains a description of the proposed use of investment proceeds, assurances that such proceeds will be used only for such use, a proposed expenditure schedule, information relevant to the criteria described in subparagraph (B), and any other information determined appropriate by the Secretary. ``(B) Approval criteria.--In allocating the limitation among plan requests of Indian tribes under subparagraph (A), the Secretary shall consider-- ``(i) the percentage of prison overcrowding in excess of the facility occupancy level as determined by the Bureau of Indian Affairs, ``(ii) the condition of existing facilities, ``(iii) the health and safety of both inmates and prison employees, ``(iv) the type of offenders incarcerated, and ``(v) other financial resources available to the Indian tribe. ``(3) Carryover of unused issuance limitation.--If for any calendar year the limitation amount imposed by paragraph (1) exceeds the amount of Indian tribal prison facility bonds issued during such year, such excess shall be carried forward to one or more succeeding calendar years as an addition to the limitation imposed by paragraph (1) and until used by issuance of such bonds. ``(h) Other Definitions and Special Rules.--For purposes of this section-- ``(1) Credit allowance date.--The term `credit allowance date' means, with respect to any issue, the last day of the 1- year period beginning on the date of the issuance of such issue and the last day of each successive 1-year period thereafter. ``(2) Bond.--The term `bond' includes any obligation. ``(3) Indian tribe.--The term `Indian tribe' has the meaning given such term by section 7871(c)(3)(E)(ii). ``(4) Qualified indian lands.--The term `qualified Indian lands' has the meaning given such term by section 7871(c)(3)(E)(i). ``(5) Partnership; s corporation; and other pass-thru entities.--In the case of a partnership, trust, S corporation, or other pass-thru entity, rules similar to the rules of section 41(g) shall apply with respect to the credit allowable under subsection (a). ``(6) Bonds held by regulated investment companies.--If any Indian tribal prison facility bond is held by a regulated investment company, the credit determined under subsection (a) shall be allowed to shareholders of such company under procedures prescribed by the Secretary. ``(7) Reporting.--Each Indian tribe with an allocation of Indian tribal prison facility bonds under an approved plan shall submit reports similar to the reports required under section 149(e).''. (b) Conforming Amendments.-- (1) Reporting.--Subsection (d) of section 6049 of the Internal Revenue Code of 1986 (relating to returns regarding payments of interest) is amended by adding at the end the following new paragraph: ``(8) Reporting of credit on indian tribal prison facility bonds.-- ``(A) In general.--For purposes of subsection (a), the term `interest' includes amounts includible in gross income under section 54(d) and such amounts shall be treated as paid on the credit allowance date (as defined in section 54(h)(1)). ``(B) Reporting to corporations, etc.--Except as otherwise provided in regulations, in the case of any interest described in subparagraph (A), subsection (b)(4) shall be applied without regard to subparagraphs (A), (H), (I), (J), (K), and (L)(i) of such subsection. ``(C) Regulatory authority.--The Secretary may prescribe such regulations as are necessary or appropriate to carry out the purposes of this paragraph, including regulations which require more frequent or more detailed reporting.''. (2) Treatment for estimated tax purposes.-- (A) Individual.--Section 6654 of such Code (relating to failure by individual to pay estimated income tax) is amended by redesignating subsection (m) as subsection (n) and by inserting after subsection (l) the following new subsection: ``(m) Special Rule for Holders of Indian Tribal Prison Facility Bonds.--For purposes of this section, the credit allowed by section 54 to a taxpayer by reason of holding an Indian tribal prison facility bond on a credit allowance date shall be treated as if it were a payment of estimated tax made by the taxpayer on such date.''. (B) Corporate.--Subsection (g) of section 6655 of such Code (relating to failure by corporation to pay estimated income tax) is amended by adding at the end the following new paragraph: ``(5) Special rule for holders of indian tribal prison facility bonds.--For purposes of this section, the credit allowed by section 54 to a taxpayer by reason of holding an Indian tribal prison facility bond on a credit allowance date shall be treated as if it were a payment of estimated tax made by the taxpayer on such date.''. (c) Clerical Amendments.-- (1) The table of subparts for part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by adding at the end the following new item: ``Subpart H. Nonrefundable Credit for Holders of Indian Tribal Prison Facility Bonds.''. (2) Section 6401(b)(1) of such Code is amended by striking ``and G'' and inserting ``G, and H''. (d) Effective Date.--The amendments made by this section shall apply to obligations issued after December 31, 2004.

Amends the Internal Revenue Code to allow a nonrefundable tax credit for investment in Indian tribal prison facility bonds. Requires that 95 percent of the proceeds of such bonds be used for the construction, acquisition, rehabilitation, expansion, or operating expenses of Indian tribal prison facilities and that the term of such bonds not exceed ten years. Establishes a national limitation for Indian tribal prison facility bonds in 2005 through 2007, with no limitation after 2007. Allows a carryover of unused bond limitation amounts to succeeding calendar years. Directs the Secretary of the Treasury to allocate bond amounts to Indian tribes based upon specified criteria, including overcrowding, the condition of existing facilities, the health and safety of both inmates and prison employees, and other financial resources available to an Indian tribe.

despite their humble appearances , the dwarf spheroidal ( dsph ) satellites of the milky way provide a source of persistent intrigue . mysteries concerning their origin , evolution , mass density , and dynamical state make it difficult to know where to place these common galaxies in the context of standard ( e.g. cold dark matter ) models of structure formation . are they primordial building blocks of bigger galaxies , or debris from galaxy interactions ? while dsph galaxies have stellar populations similar in number to those of globular clusters ( @xmath2 ) , their stars are spread over a much larger volume ( @xmath3-@xmath4 kpc compared to @xmath5-@xmath6 pc in globular clusters ) resulting in the lowest luminosity ( i.e. , baryonic ) densities known in any type of galaxy . in many cases it is unclear how these galaxies could have avoided tidal disruption by the milky way over their lifetimes without the addition of considerable unseen mass . this characteristic of dsph galaxies suggests that the dynamics of these systems are dominated either by significant amounts of unseen matter , or that these galaxies are all far from dynamical equilibrium . in general , the jeans equations ( equations ( 4 - 21 ) , ( 4 - 24 ) , and ( 4 - 27 ) of binney & tremaine 1987 @xcite , hereafter , bt87 ) provide a robust description of the mass distribution , @xmath0 , of a collisionless gravitational system such as a dsph galaxy in viral equilibrium , equation ( [ eq : em ] ) below . their general form permits any number of mass components ( stellar , gas , dark ) , as well as anisotropy in the velocity dispersion tensor and a non - spherical gravitational potential . when applied to spherical stellar systems and assuming at most only radial or tangential velocity anisotropy , these equations can be simplified to estimate the radial mass distribution ( equation 4 - 55 of bt87 ) : @xmath7 where @xmath8 is the spatial density distribution of stars , @xmath9 is the mean squared stellar radial velocity at radius @xmath1 . the dimensionless isotropy parameter , @xmath10 , compares the system s radial and tangential velocity components : @xmath11 apart from the constraints on the geometry and the functional form of the anisotropy , equation ( [ eq : mrjeans ] ) is model - independent , making it an appealing tool . it is relevant that equation ( [ eq : mrjeans ] ) and ( [ eq : jns1 ] ) below are applicable to any tracer population that in equilibrium and satisfies the collisionless boltzman equation . kinematic datasets for individual dsph galaxies have historically been far too small ( typically containing radial velocities for @xmath12 30 stars ; see mateo 1998 ) to allow for a precise determination of @xmath0 using relations similar to equation ( [ eq : mrjeans ] ) . instead , authors have been forced to adopt additional strong assumptions that reduce the jeans equation to even simpler forms and where the relevant distributions ( @xmath13 and @xmath14 in equation [ eq : mrjeans ] ) are represented by parametric models . specifically , if one assumes isotropy of the velocity dispersion tensor ( i.e. , @xmath15 ) , spherical symmetry , and that the starlight traces the mass distribution ( effectively a single - component king model ( irwin and hatzidimitriou 1995 ) ) , then one obtains for the m / l ratio ( richstone and tremaine 1986 ) : @xmath16 where @xmath17 is the one - dimensional central velocity dispersion , @xmath18 is the central surface brightness , and @xmath19 is the half - light radius . the parameter @xmath20 is nearly equal to unity for a wide range of realistic spherical dynamical models so long as the mass distribution is assumed to match that of the visible matter . with this approach the modern variant of the classical ` king fitting ' procedure ( king 1966 ) the measured central radial velocity dispersion and surface brightness yield estimates of such quantities as the global and central m / l ratios . in all eight of the mw s measured dsphs , large central velocity dispersions have conspired with their low surface brightnesses to produce large inferred m / l values . this line of reasoning has led to a general belief that dsph galaxies are almost completely dark - matter dominated , and their halos have assumed the role of the smallest non - baryonic mass concentrations identified so far in the present - day universe . this analysis fails for galaxies that are far from dynamical equilibrium , for example due to the effects of external tidal forces from the milky way ( fleck and kuhn 2003 ; klessen and kroupa , 1998 ) . numerical models aimed to investigate this ( oh et al . 1995 ; piatek and pryor 1995 ) generally found that tides have negligible effects on the central dynamics of dsph galaxies until the survival time of the galaxy as a bound system becomes comparable to the orbital time ( about 1 gyr for the closer dsph satellites of the milky way ) . observations agree with this broad conclusion by finding that remote dsph galaxies are no less likely to contain significant dark matter halos than systems located closer to their parent galaxy ( mateo et al . 1998 ; vogt et al . 1995 ) . however , so - called resonance models ( fleck and kuhn 2003 ; kuhn 1993 ; kuhn et al . 1996 ) have been proposed that imply the central velocity dispersions can be significantly altered due to the inclusion of stars streaming outward from the barycenter of a galaxy and projected near the galaxy core . recent versions of these models invariably imply a significant extension of the affected galaxies along the line - of - sight ( more precisely , along the line between the center of the dwarf and the milky way ; kroupa 1997 ; klessen and kroupa 1998 ) and a massive tidal stream along the satellite s orbit . observations do not reveal strong evidence of significant line - of - sight distortions in dsph galaxies ( hurley - keller et al 1999 ; klessen et al . 2003 ) , other than sagittarius ( e.g. ibata et al . 1995 ) ; thus , for the purposes of this paper , we will assume that dsph galaxies are generally close to a state of dynamical equilibrium . even with this enabling assumption , the classical analysis of dsph masses as we describe it above is far from ideal for a number of reasons . first , though recent work ( e.g. irwin and hatzidimitriou 1995 ) has helped to greatly improve estimates of dsph structural parameters ( @xmath21 and @xmath22 in equation [ eq : moverl ] ) , the errors in the velocity dispersions often dominated by poisson uncertainties due to the small number of kinematic tracers contribute the principle source of uncertainty in m / l estimates . second , there is little reason to suppose the assumption that mass follows light in dsphs is valid . in all other galaxies the bulk of the matter resides in a dark halo extending far beyond the luminous matter , a trend that becomes more exaggerated toward smaller scales ( kormendy and freeman 2004 ) . finally , velocity anisotropies , if they exist , may mimic the presence of dark matter , and so represent a tricky degeneracy in the model even if the assumption of isotropy is dropped . modern instrumentation is poised to deliver dramatically larger kinematic datasets to help minimize the first problem . for example , the michigan / magellan fiber system , now operational at the magellan 6.5-m telescopes , obtains spectra from which high - precision radial velocities can be measured of up to 256 objects simultaneously . as a result , it is now feasible to obtain thousands of individual stellar spectra in many dsph systems , enlarging sample sizes by more than an order of magnitude . this not only reduces the statistical uncertainty of the dispersion estimation , but can also provide information on the spatial variation of the dispersion across the face of a galaxy . these rich datasets therefore allow for fundamentally improved results even using fairly conventional analysis techniques . for example , by parameterizing the velocity anisotropy , wilkinson et al . ( 2002 ) and kleyna et al . ( 2002 ) show that samples of @xmath23 stars can begin to break the degeneracy between anisotropy and mass in spherical systems . but these large datasets also allow us to aim higher . in this paper , we introduce and develop the formalism for a qualitatively different sort of analysis designed to make the most efficient use of large kinematic datasets . rather than adopting a model that parameterizes the various distributions used in the jeans equation ( e.g. , @xmath0 , @xmath13 , @xmath24 , or @xmath10 ) , we operate on the star count and radial velocity data directly to estimate the mass distribution non - parametrically . we estimate the true three - dimensional mass distribution from the projected stellar distribution and the line - of - sight velocity distribution . in this first application of our technique , we still require the assumptions of viral equilibrium , spherical symmetry , and velocity isotropy ( @xmath15 ) . in section 2 , we introduce notation and definitions of the three - dimensional as well as projected stellar and phase - space densities and review the jeans equation . in sections 3 and 4 , we show how to use very general shape constraints on the mass distribution to estimate the detailed form of the velocity dispersion profile and the radial mass distribution . we illustrate the process on simulated data , demonstrating that , when furnished with large datasets , nonparametric analysis is a powerful and robust tool for estimating mass distributions in spherical or near - spherical systems ( section 5 ) . we illustrate the application of our approach to an existing but relatively small kinematic dataset for the fornax dsph galaxy at the end of section 5 . our emphasis in this paper is the application of our technique to dsph kinematics , but the method described in this paper is applicable to any dynamically hot system in which the radial velocity field is sampled discretely at the positions of a tracer population . thus , our methodology would work for , say , samples of globular clusters or planetary nebulae surrounding large elliptical galaxies , or for individual stars within a globular cluster . our approach follows earlier non - parametric analysis of globular cluster kinematics by gebhardt and fischer ( 1995 ) and merritt et al . ( 1997 ) , though the details of our method differ significantly . let @xmath25 and @xmath26 denote the 3-dimensional position and velocity of a star within a galaxy . we will regard these as jointly distributed random vectors , as in bt87 , p. 194 . suppose that @xmath27 and @xmath28 have a joint density that is spherically symmetric and isotropic , so that @xmath29 = f_0(r , v)d{{\mbox{\boldmath$x$}}}d{{\mbox{\boldmath$v$}}},\ ] ] where @xmath30 and @xmath31 . we also suppose that @xmath32 has been centered to have a mean of zero so that @xmath33 suppose finally that the mass density @xmath34 is spherically symmetric and let @xmath35 the total mass within @xmath1 of the center . the goal of this paper is to come up with a means of estimating @xmath0 non - parametrically , specifically without assuming any special functional form for @xmath36 or @xmath34 . in the presence of spherical symmetry , the relevant form of the jeans equation is @xmath37,\ ] ] where @xmath38 and @xmath39 in statistical terminology , @xmath40 is the conditional expectation of @xmath41 given @xmath42 ( this is the same as the conditional expectation on @xmath43 , hence the factor of 3 ) , and the marginal density of @xmath44 is @xmath45 . in astronomical terms , @xmath40 is the one - dimensional radial - velocity dispersion profile squared , and @xmath45 is the true , three - dimensional density profile of the tracer population . using the notation of bt87 , these correspond to @xmath24 and @xmath13 , respectively . to estimate @xmath0 from equation ( [ eq : jns1 ] ) clearly requires estimates of the functions @xmath46 and @xmath47 . for dsph galaxies , the data available for this consist of a large sample of positions and photometry of stars in individual systems ( irwin and hatzidimitriou 1995 ; hereafter ih95 ) , and much smaller samples of stars with positions and velocities ( e.g. walker et al . 2004 ) . of course , it is not possible yet to determine complete three - dimensional positional or velocity information for any of these stars , but only the velocity in the line of sight and the projection of position on the plane orthogonal to the line of sight . with a proper choice of coordinates , these observables become @xmath48 , and @xmath49 . these can be made equivalent to , say , right ascension and declination , and radial velocity , respectively . the incomplete observation of @xmath32 does not cause a problem here , given the assumed isotropy , since @xmath50 can be replaced by @xmath51 in equation ( [ eq : mu ] ) without changing the value of @xmath40 . the incomplete observation of position poses a more serious problem that is known as wicksell s ( 1925 ) problem in the statistical literature . the procedures for estimating @xmath46 and @xmath47 are consequently different ; they will be considered separately in sections 3 and 4 . let @xmath53 and @xmath54 denote the true three - dimensional distance of a star and its two - dimensional projected distance from the origin , respectively . we denote the corresponding densities as @xmath55 and @xmath56 . then @xmath57 , and @xmath58 for an example , consider plummer s distribution , @xmath59_{+}^{7\over 2},\ ] ] where @xmath60 is a constant , and @xmath61 is a parameter that is related to the velocity dispersion through @xmath62}$ ] . here @xmath1 is measured in units of 100 pc and @xmath63 in km / s . we also employ here the notation @xmath64_{+}$ ] to denote taking the larger of @xmath65 and @xmath66 . with this definition , we take @xmath64_+^\alpha$ ] to be shorthand for @xmath67_+)^\alpha$ ] ; that is , the value of @xmath65 is either positive or zero before raising to the power @xmath68 . for this case , @xmath69 $ ] and @xmath70 $ ] . we use the plummer distribution in our simulations below . ih95 provide data from which @xmath46 can be estimated . these data consist of a sample of stars with projected radii @xmath71 and counts @xmath72 of the number of stars for which @xmath73 where @xmath74 divide the stars into bins . let @xmath75 denote the distribution function of @xmath76 , so that @xmath77 = \int_{0}^{s } g_{\bf s}(t)dt$ ] . then @xmath78 may be estimated from its empirical version @xmath79 in this context and throughout this paper , the @xmath80 symbol denotes functions estimated directly from empirical data . since the samples of stars used by ih95 to determine the surface density of most of the milky way dsph galaxies are quite large , there is generally very little statistical uncertainty in our estimate of @xmath81 from equation ( [ eq : estgee ] ) . if we now model @xmath46 by a step function , say @xmath82 for @xmath83 and @xmath84 , then @xmath85 may be recovered directly . in this case , the integral in equation ( [ eq : fg ] ) is easily computed leading to @xmath86 where @xmath87.\ ] ] then @xmath85 may be recovered from @xmath88.\ ] ] the summation is to be interpreted to be zero when @xmath89 , and the right side of equation ( [ eq : gf ] ) can in practice be estimated by replacing @xmath75 with its empirical version @xmath90 . the results of applying this method to a sample of 150,000 positions drawn from a plummer model with @xmath91 are shown in figures [ fig : counts ] and [ fig : fbar ] . figure [ fig : counts ] shows simulated counts of the number of stars in equally - spaced bins ranging from @xmath92 . the estimate of @xmath46 from these simulated data is shown in figure [ fig : fbar ] . in both figures the dotted line denotes the true function . the estimation of @xmath46 follows wicksell s ( 1925 ) original analysis and can almost certainly be improved . we have not done that here , because the sample sizes are so large , but related questions are currently under investigation by pal ( 2004 ) . for estimating @xmath47 and @xmath94 it is convenient to work with squared radius @xmath95 , as in groeneboon and jongbloed ( 1995 ) and hall and smith ( 1992 ) . the joint density of @xmath96 is then @xmath97 relation ( 7 ) represents a special case on integrating over all three velocity components and using @xmath98 . now let @xmath99 and @xmath100 so that @xmath101 is the conditional expectation of @xmath102 given @xmath103 , and similarly for @xmath104 . we also define the important function @xmath105 then , reversing the orders of integration and recognizing a beta integral ( see bt87 , p. 205 ) , we can write @xmath106 and @xmath107 where the prime notation ( @xmath108 ) denotes the derivative . clearly , @xmath109 in equation ( [ eq : mu ] ) . thus , the expression for @xmath0 from the jeans equation ( equation ( [ eq : jns1 ] ) ) can be rewritten as @xmath110 our estimator for @xmath46 was obtained in section 3 , so we focus here on determining @xmath111 . for our problem , we benefit from noting that the function @xmath112 is subject to certain shape restrictions which are useful in the estimation process . from equation ( [ eq : psi ] ) we can see that @xmath112 is a non - negative decreasing function , while from equation ( [ eq : jns2 ] ) it is evident that @xmath112 has a non - negative second derivative ( that is , it is upward convex ) . in fact , @xmath113 must be an increasing function that vanishes when @xmath114 , physically consistent with its direct proportionality to @xmath0 in equation ( [ eq : jns2 ] ) . the next step in the estimation of @xmath0 is to estimate @xmath112 . suppose that there is a sample @xmath115 of projected positions @xmath116 and radial velocities @xmath117 measured with known error , @xmath118 . thus , @xmath119 , where where @xmath120 are independent of @xmath121 with zero mean values and known variances , @xmath122 . in practice , there may be selection effects : an astronomer may choose to sample some regions of a galaxy more intensely than others , or external factors ( weather , moonlight , telescope / instrument problems ) may cause undersampling of some regions . to address this , we must include a selection function , @xmath123 , into the model . here , @xmath123 is the probability that a star in a galaxy is included in the kinematic sample , given that it is there . thus the selection probability is assumed to depend on projected position , @xmath124 , only . as before , let @xmath125 ; then the joint density of @xmath126 and @xmath127 in the sample is @xmath128 where @xmath129 d\theta,\ ] ] @xmath130 is as in equation ( [ eq : vy ] ) , and @xmath131 is a normalizing constant , determined by the condition that the integral of @xmath132 be one . integrating over @xmath133 in ( [ eq : slctn1 ] ) , the actual density of @xmath134 is @xmath135 and @xmath131 is determined by the condition that @xmath136 . here @xmath137 may be determined from the complete photometric data for a given galaxy to give the projected stellar distribution as a function of @xmath134 . if @xmath46 is a step function , then combining equations ( [ eq : fg ] ) and ( [ eq : gf ] ) with the relation @xmath138 leads to @xmath139\ ] ] in the interval @xmath140 for @xmath141 . if an astronomer can specify @xmath123 , then @xmath131 and @xmath142 can be computed directly using equation ( 15 ) . then @xmath143 is an unbiased estimator of @xmath144 for each @xmath145 ; that is , @xmath146 for each @xmath145 . if an astronomer can not specify @xmath147 , then it must be estimated from the data . the first step is to estimate @xmath148 , which can in principle be done in many ways . the simplest is to use a kernel estimator of the form @xmath149 where @xmath150 is a probability density function , called the _ kernel _ , and @xmath61 is a positive factor called the _ bandwidth _ that may be specified by the user or computed from the data . silverman ( 1986 ) is a recommended source for background information on kernel density estimation . possible choices of @xmath150 and the computation of @xmath61 are discussed there . other methods for estimating @xmath148 include local polynomials [ 79 - 82 , loader 1999 ] and log - splines [ 178 - 179 , gu 2002 ] . whichever method is adopted , once @xmath151 has been estimated , @xmath152 may be subsequently estimated by @xmath153 then @xmath112 can be estimated by replacing @xmath152 with @xmath154 in ( [ eq : psisharp ] ) . in this case @xmath155 is no longer exactly unbiased , but it is at least consistent in the statistical sense that as the number of data points increases , the estimator continuously tends ever closer to the true value . generally , @xmath156 does not satisfy the shape restrictions when viewed as a function of @xmath145 : @xmath156 is unbounded as @xmath145 approaches any of the data points @xmath126 . it is decidedly not monotone nor convex ( see figure [ fig : psi ] ) . for these reasons @xmath155 may be called the _ naive _ estimator . this naive estimator can be improved by imposing physically justified shape restrictions on @xmath0 . one can imagine a wide range of possible model forms for @xmath0 , but in the spirit of attempting a non - parametric solution , we adopt a simple spline of the form @xmath157^p_{+},\ ] ] where @xmath74 are knots , @xmath158 are constants , and @xmath159^p$ ] . the simplest case is for @xmath160 , but this form for @xmath0 leads to a divergent estimate of the central velocity dispersion , @xmath161 . for @xmath162 , @xmath163 as @xmath164 ; thus , @xmath165 provides an estimate of the central mass density with the correct asymptotic behavior at the galaxy center . unfortunately , translating the shape restrictions on @xmath0 into conditions on @xmath158 is much more difficult when @xmath162 than for @xmath166 . for this paper we have chosen to compromise with @xmath167 because it leads to a good estimate of @xmath161 yet is still amenable to the application of the shape restrictions we described above . we plan to tackle the case @xmath168 in a future paper . for our adopted case ( @xmath167 ) the expression ( equation ( [ eq : spln1 ] ) ) for the mass , @xmath0 , is a quadratic spline : @xmath169 ^ 2_{+}.\ ] ] one natural constraint is that @xmath0 remain bounded as @xmath170 . expanding equation ( [ eq : spln2 ] ) to read @xmath171 for @xmath172 , we see that this constraint is equivalent to requiring that @xmath173 , and @xmath174 . from this first equality constraint ( @xmath173 ) , we can trivially say @xmath175 and , therefore , @xmath176 ^ 2_{+ } - [ r - r_{m-1}]_{+}^{2}\big\}.\ ] ] we also require that @xmath0 be a non - decreasing function of @xmath1 ( no negative mass ) , or equivalently that the derivative @xmath177 be non - negative . it is clear from equations ( [ eq : spln2 ] ) and ( [ eq : spln3 ] ) that @xmath177 is a piecewise linear function that is constant on the interval @xmath178 . thus , the condition that @xmath0 be non - decreasing is equivalent to requiring that @xmath179 for @xmath180 . that is , @xmath181 for @xmath182 . for the case @xmath183 , this constraint can be written as @xmath184 . this is clear from noting that we do not change this summation if we replace @xmath185 with @xmath186 ; thus we can write @xmath187 , where we have used the facts that @xmath188 and that @xmath174 as required by equation ( [ eq : spln2 ] ) . these are the constraints imposed on @xmath189 that we employ below to estimate @xmath0 . if we solve for @xmath111 in equation ( [ eq : jns2 ] ) , we can write @xmath190 where @xmath191_{+}^{2}-[r - r_{m-1}]_{+}^{2}\big),\ ] ] for notational convenience , we define @xmath192 , then solve for @xmath193 in terms of the coefficients @xmath194 to get @xmath195 where @xmath196 for @xmath197 . the next step is to impose the shape restrictions implicit in equation ( [ eq : jns2 ] ) . if @xmath155 were square integrable , this could be directly accomplished by minimizing the integral of @xmath198 ^ 2 $ ] , or equivalently by minimizing @xmath199 with respect to the coefficients , @xmath194 . the function @xmath155 is not integrable , essentially because @xmath200 , but @xmath201 can still be minimized . letting @xmath202 be the vector @xmath203^t$ ] , this criterion may be expressed in matrix notation as @xmath204 where the elements of the vector @xmath205 are given by @xmath206 and the elements of @xmath207 are given by @xmath208 for @xmath209 . thus , the estimation problem for @xmath112 leads to a quadratic programming problem of minimizing @xmath201 in equation ( [ eq : kappa ] ) subject to condition ( [ eq : cnstrnt1 ] ) with equality when @xmath210 . if we can determine @xmath211 and @xmath212 , we can estimate the coefficients @xmath194 which in turn gives us our estimate for @xmath0 . observe that the @xmath211 depend explicitly on both the deduced stellar density distribution , @xmath46 , and the velocity dispersion profile derived from a set of radial velocity tracers , @xmath47 . the @xmath212 depend only on @xmath45 . let @xmath213 be defined as @xmath214 \nonumber \\ & & \ \ \ \ \ \ \ \ \ \ + { 1\over n}\sum_{i : y_i\le z}{u_i^2-\sigma_i^2\over w(y_i)}\left[-{4\over 3 } y_i^{3\over 2}+2zy_i^{1\over 2 } \right],\end{aligned}\ ] ] where the weighting function , @xmath152 , may be specified or estimated as described earlier in this section . then @xmath211 can then be computed numerically as @xmath215 this form for the @xmath211 is simpler to evaluate than the double integral form for these terms given earlier . in a similar fashion we can write @xmath212 as @xmath216 - { ( s+t ) \min[s , t]^2\over 2 } + { \min[s , t]^3\over 3}\right ] \gamma_i(s ) \gamma_j(t ) dt ds \nonumber \\\end{aligned}\ ] ] these integrals ( [ eq : zi ] ) and ( [ eq : qij ] ) can be computed explicitly and matlab codes are available at website _ http://www.stat.lsa.umich.edu/~wangxiao _ to do so . if we define @xmath217 as the solution to the quadratic minimization problem ( see equation ( [ eq : kappa ] ) ) , our estimates of @xmath218 , @xmath219 , @xmath40 , and @xmath0 can be denoted using analogous notation and are given by @xmath220 @xmath221 @xmath222 and , @xmath223 ^ 2_+ -\left[r - r_{m-1}\right]_+^2\right\}.\ ] ] the latter two functions specify the projected radial velocity and mass profiles , respectively . to illustrate an application of our approach , we have drawn a sample of 1500 @xmath224 pairs from a plummer model with @xmath225 and @xmath226 ( see figure [ fig : su ] ) . the naive estimator @xmath227 may be computed from these data using equation ( [ eq : psisharp ] ) and it is shown in figure [ fig : psi ] , along with the improved estimator @xmath228 . the need for the improved estimator for @xmath112 is clear since , as expected , @xmath227 is a highly irregular function which reacts strongly to the presence of individual data points . the estimated velocity dispersion profile , @xmath229 is presented in figure [ fig : mu ] and the estimated mass profile , @xmath230 , is illustrated in figure [ fig : mass ] . in all cases , the dotted line represents the true functions computed directly from the plummer model from which the @xmath224 pairs were drawn . in these figures @xmath231 , @xmath232 , and @xmath233 . the last plataux on the right in figure [ fig : mass ] ( @xmath234 ) deserves comments , because it illustrates an important feature of the problem in general and our method in particular : estimates become unreliable for large values of @xmath1 , because the data become sparse , and shape restricted methods are especially prone to problems such problems woodroofe and sun ( 1993 ) . deciding exactly where reliability ends is difficult , but the confidence bands of figures [ fig : masscb ] and [ fig : diffsample ] provide some indication . in the example of figure 6 , they correctly predict that reliability deteriorates abruptly for @xmath234 and , interestingly , make the same prediction for a range of sample sizes . there are several sources of error in our derived velocity dispersion and mass profile estimators which may be divided into the broad classes of modeling error , systematic error , and statistical error . while quite general , our assumptions also represent some over - simplification and these too introduce uncertainty to our results . the assumption of spherical symmetry , for example , ignores the known ellipticities seen in most dsph galaxies ( ih95 , mateo 1998 ) . but even if we assume our working assumptions were all correct , systematic error will develop from our approximations of distributions as step functions , piecewise linear functions , and quadratic splines . on general grounds , this error will be small provided that the underlying true functions are smooth , so we feel justified in ignoring this source of systematic error . we have also ignored the statistical error in the estimation of @xmath46 in section [ sect : h ] , because the sample sizes in ih95 are so large . that leaves the statistical error in the kinematic data as the principle source of uncertainty in our estimation of @xmath112 and the estimators of @xmath47 and @xmath94 . to quantify the magnitude of this error , let @xmath235 denote the error committed when estimating @xmath0 , and let @xmath236 denote the @xmath237 percentile of its distribution distribution , so that @xmath238 = \alpha$ ] . then @xmath239 = 1 - 2\alpha,\ ] ] and @xmath240 $ ] is a @xmath241 percent confidence interval for @xmath0 . within the context of plummer s model , the @xmath236 can be obtained from a monte carlo simulation . if we generate @xmath242 samples from plummer s model , we obtain @xmath242 values for the errors @xmath243 , which we denote as @xmath244 . then @xmath236 may be estimated by the value of @xmath145 for which the @xmath245 of the @xmath246 are less than or equal to @xmath145 . we applied this procedure to a grid of @xmath1 values with @xmath247 and @xmath248 and then connected the resulting bounds to in a continuous piecewise linear fashion to obtain the 95% and 68% confidence bounds shown in figure [ fig : masscb ] . the 95% and 68% confidence bounds for @xmath47 shown in figure [ fig : mucb ] were obtained in a similar manner . the procedure just outlined requires knowing the true @xmath0 and the distributions of @xmath134 and @xmath49 from the plummer model . but the exercise is still useful since it shows the intrinsic accuracy of the estimation procedure . for example , when the sample size is @xmath249 , the estimator of @xmath0 has very little accuracy for @xmath250 . somewhat surprisingly , the estimator for @xmath0 retains reasonable accuracy for @xmath251 despite the lack of much data beyond @xmath252 ( see figure [ fig : counts ] ) . we have also explored how our estimates fare with significantly smaller samples of tracers with known positions and velocities ( i.e. , fewer @xmath224 pairs ) . figure [ fig : diffsample ] shows @xmath253 percent confidence bounds for the estimates of @xmath0 and @xmath40 based on sample sizes @xmath254 , @xmath255 , @xmath256 and @xmath257 stars . as one might expect , the confidence bounds expand as the sample size decreases , but , interestingly , the radial location of where the estimator performs poorly only very slowly migrates to smaller values of @xmath1 as the sample shrinks . the requirement that we know @xmath0 and the distribution of @xmath134 and @xmath49 ahead of time in order to estimate the confidence bounds can be avoided by using a bootstrap procedure . in its simplest form , the bootstrap can be implemented as follows : given a sample of @xmath258 values ( corresponding to the observable projected position and radial velocity for each star in a kinematic sample ) , first compute @xmath230 . then generate @xmath259 samples with replacement objects , one selects a new sample of @xmath186 values from the original values @xmath260 . the new sample differs from the original in that each value @xmath260 is returned to the sample before choosing the next value @xmath261 . in this way , some values from the original sample will invariably be chosen more than once to form the bootstrap sample . ] from the given sample and compute estimators @xmath262 for each of these samples . let @xmath263 and estimate the percentiles of @xmath264 as described above . letting @xmath265 denote the estimated @xmath237 percentile , @xmath266 $ ] is the bootstrap confidence interval for @xmath0 . for more details , see efrom and tibshirani ( 1993 ) who provide a good introduction to bootstrap methods . this approach offers a practical way of assessing the statistical errors in @xmath229 and @xmath230 of an actual kinematic sample . there is also the possibility of obtaining large - sample approximations to the error distribution . from ( [ eq : zi ] ) , it is clear that the @xmath211 are approximately normally distributed in large samples . this suggests that the distribution of @xmath267 should be approximately the same as the distribution of a shape - restricted estimator in a normal model . unfortunately , calculating the latter is complicated . some qualitative features are notable , however . monotone regression estimators are generally quite reliable away from the end points , but subject to the _ spiking problem _ near the end points . for non - decreasing regression , the estimator has a positive bias near large values of the independent variable ( in this case , @xmath1 ) , and a negative bias at small values of the independent variable ( i.e. for @xmath268 ) . the positive bias at large @xmath1 is very clearly seen in figure [ fig : masscb ] and is exacerbated by the sparsity of data . the negative bias near @xmath114 is not evident because it is ameliorated by two effects . first , the mass distribution is known to be always positive ( @xmath269 ) and goes to zero at @xmath114 ( @xmath270 ) . this eliminates bias at @xmath114 . second , our assumption ( [ eq : spln3 ] ) requires @xmath230 to be of order @xmath271 for small @xmath1 , while @xmath0 is on physical grounds known to approach zero as @xmath272 for small @xmath1 . as an application to real observational data , we have use the radial velocity data from walker et al ( 2005 ) for the fornax dsph galaxy . this dataset consists of velocities for 181 stars observed one at a time over the past 12 years ( mateo et al . 1991 has a description of some of the earliest data used here ) . data from newer multi - object instruments are not included here ( see walker et al 2005b for a first analysis of these newer results ) . full details about the observations can be found in the papers referenced above ; for the present application we simply adopt these results along with their quoted errors to see what sort of estimator for @xmath0 we can extract from these data . from the simulations we already know that the dataset is relatively small for this method , but these simulations also imply that we have no reason to expect a strong bias in our mass estimator due to the sample size , only a potentially large uncertainty ( at least a factor of 2 ) in the final mass estimate . the histogram of the star counts from ( irwin and hatzidimitriou 1995 ) is shown in the first panel of figure [ fig : fornax1 ] . the remaining two panels in figure [ fig : fornax1 ] show the derived estimates for the spatial density of stars in fornax @xmath273 and the true projected radial distribution of stars in fornax @xmath274 . the bottom panels of figure [ fig : fornax21 ] give the estimated projected radial distribution of stars from ( walker et al , 2004 ) and the estimated selection function @xmath275 derived from the data . figure [ fig : fornax22 ] show the mass profile , @xmath230 and the squared velocity dispersion profile , @xmath229 . previous estimates of the fornax mass have been based primarily on the classical , or king ( 1966 ) analysis outlined in the introduction of this paper , and give @xmath276 range from @xmath4 to @xmath277 m@xmath278 ( mateo et al . 1991 ; walker et al . these models resemble truncated isothermal spheres and implicitly assume spherical symmetry , velocity isotropy , that mass follows light , and a specific parametric form for the joint density function @xmath36 . our mass distribution estimator provides an independent measurement employing neither of the latter two assumptions . if one believes the second plateau seen at @xmath279 kpc in figure [ fig : fornax22 ] ( first panel ) is a real feature , this would indicate a fornax mass of @xmath280 . however , we note that the simulations using plummer models ( figure [ fig : diffsample ] ) show similar plateaux at large radii related not to the underlying mass , but rather to the scarcity of remaining data points . the first plateau ( @xmath281 kpc ) , by contrast , covers a region for which the plummer simulations indicate even a relatively small dataset can yield a reasonable estimate of the mass . we therefore consider the two plateaux in the @xmath0 curve of figure [ fig : fornax22 ] to bracket the region of plausible fornax mass as measured from an n @xmath12 200 sample by the estimation technique . the resulting interval of @xmath282m@xmath278 @xmath283m@xmath284 @xmath285 @xmath286 m@xmath278 is of considerably larger mass than the results of the classical analysis . the estimation approach then offers an attractive alternative to variants of the classical analysis that require parametric dynamical models to interpret kinematic data for dsphs . our simulations show that this new non - parametric analysis will provide significantly more accurate results as kinematic samples grow larger . finally , we can make some comments regarding the effect of velocity anisotropy in our results . if we consider an extreme case where the outermost bins of the fornax velocity dispersion profile are dominated by stars in tangential orbits ( that is , @xmath287 ; see equations ( [ eq : mrjeans ] ) and ( [ eq : jbeta ] ) ) , then the outer bins give us the mass directly ( from equation [ eq : mrjeans ] ) as @xmath288 , or @xmath289 m@xmath278 , which is equivalent to the lower limit provided by the mass estimation technique . thus , even if we consider an extreme breakdown of the isotropy assumption , the data alone support a larger mass than the simple king analysis . since it is more likely that the velocity distribution has intermediate anisotropy ( kleyna et al . 2002 ) , we conclude that the the mass of fornax to the outermost measured data point is between @xmath290 and @xmath286 m@xmath291 for an observed luminosity of @xmath292 l@xmath278 for fornax , this gives a global m / l ratio ranging from 7 to 22 . thus , even the most luminous , most baryonic - dominated dsph satellite of the milky way is dominated by dark matter . we have presented a new method for estimating the distribution of mass in a spherical galaxy . along the way , we have made some choices , generally preferring the simplest of several alternatives for example , the use of quadratic splines in section 4 and simple histograms in section 3 . in spite of this , the algorithm is a bit complicated . is it really better than simpler methods for example , using kernel smoothing to estimate the distribution of projected radii and line of sight velocities and then using inversion to estimate @xmath0 ? our method differs from the simpler approach through its essential use of shape restrictions . from a purely statistical viewpoint , the monotonicity of @xmath113 in equation ( [ eq : jns2 ] ) provides a lot of useful information [ robertson , et.al . ( 1988 ) ] . early in our investigations , we tried the kernel smoothing outlined above and found that the resulting estimators did not satisfy the shape restriction , leading to negative estimates of the mass density . imposing the shape restrictions directly guarantees non - negative estimates , at least . it also reduces the importance of tuning parameters , like the bandwidth in kernel estimation or the number of bins in our work . imposing the shape restrictions also complicates the algorithm and leaves a quadratic programming problem at the end . we think that the game is worth the candle . there is some similarity between our method and that of merritt and saha ( 1993 ) in that both use basis functions , splines in our case , and both impose shape restrictions , the condition that @xmath293 in theirs . our method makes more esssential use of shape restrictions and treats the inversion problem in greater detail .

thanks to instrumental advances , new , very large kinematic datasets for nearby dwarf spheroidal ( dsph ) galaxies are on the horizon . a key aim of these datasets is to help determine the distribution of dark matter in these galaxies . past analyses have generally relied on specific dynamical models or highly restrictive dynamical assumptions . we describe a new , non - parametric analysis of the kinematics of nearby dsph galaxies designed to take full advantage of the future large datasets . the method takes as input the projected positions and radial velocities of stars known to be members of the galaxies , but does not use any parametric dynamical model , nor the assumption that the mass distribution follows that of the visible matter . the problem of estimating the radial mass distribution , @xmath0 ( the mass interior to true radius @xmath1 ) , is converted into a problem of estimating a regression function non - parametrically . from the jeans equation we show that the unknown regression function is subject to fundamental shape restrictions which we exploit in our analysis using statistical techniques borrowed from isotonic estimation and spline smoothing . simulations indicate that @xmath0 can be estimated to within a factor of two or better with samples as small as 1000 stars over almost the entire radial range sampled by the kinematic data . the technique is applied to a sample of 181 stars in the fornax dsph galaxy . we show that the galaxy contains a significant , extended dark halo some ten times more massive than its baryonic component . though applied here to dsph kinematics , this approach can be used in the analysis of any kinematically hot stellar system in which the radial velocity field is discretely sampled .

Elaine Lissner is the director of the Male Contraception Information Project and of Parsemus Foundation, an organization dedicated to sponsoring contraceptive developments that include Vasalgel and an H.I.V. transmission-reducing pill. Imagine you’re a 20-something or 30-something man, out on the dating market. You have grad school planned for the fall and your whole life ahead of you. You meet a woman who seems pretty promising; after you’ve been dating a number of months, you stop using condoms, because she’s on the pill. But you just read an article that said even among highly motivated young college women, about half forgot to take roughly three pills per cycle. Nervous yet? If we’re serious about wanting new choices, we need to finish the work that has been started. In the effort to improve family planning options, we’ve somehow overlooked half of humanity: men haven’t gotten a new option in more than a century. And it’s not that men aren’t interested: Men are already using the only two methods they have – condoms, which are not perfect, and vasectomy, which is basically permanent – in great numbers. Add in withdrawal, and men are covering nearly a third of U.S. contraceptive use. At least in the United States, the idea that men aren’t willing to participate is clearly out of date. Yet developing long-acting, reversible methods for men is still not seen as a priority. The Bill and Melinda Gates Foundation and U.S.A.I.D. are getting serious about new long-acting options for women; not so, yet, for men. National Institutes of Health funding helps some researchers make it through the first steps, but cannot finish the multimillion-dollar task of seeing potential products through to market. So will a new method always be five to 10 years away? Not if we stay focused. The pipeline is already full, and if we’re serious about wanting new choices, we need to finish the work that has been started, not do more basic research. More than 23,000 men and women have signed a petition calling for new methods, and 18,000 men and women are waiting to hear about clinical trials for Vasalgel, the method furthest along. Individual men desperate to have more control over their reproductive destinies have been donating thousands of dollars to the project. Given the lack of large-scale funder support, Vasalgel is the method most likely to make it to the U.S. market in the near future; it is fortunate to be a device, not a drug, and to have a growing popular movement behind it. If social investors step up, it has a chance. But it is also near-criminal that a method like the "Clean Sheets Pill," which is not as far along but could drastically reduce H.I.V. transmission, is stalled for want of one $300,000 study. Stay focused, devote the proper scale of resources, and finish the job. Is that so much for men (and their partners) to ask? Join Opinion on Facebook and follow updates on twitter.com/roomfordebate. ||||| Scientists have been working on a form of male birth control for years now, but it’s possible that we finally have a winner. Vasalgel, a non-hormonal polymer that blocks the sperm-shooting vas deferens in men, has shown promising results in a baboon study and could be available by 2017. The Parsemus Foundation, a nonprofit organization that develops low-cost medical approaches, aims to start human trials for this contraceptive by next year. After finding that baboons injected with Vasalgel didn’t impregnate the 10 to 15 female baboons with which they shared the same space, scientists saw the possibility of the injection working in humans, too. Vasalgel is non-hormonal and only requires a single shot to be effective for a long time. A polymer contraceptive is injected into the vas deferens, which transports sperm from the epididymis to the ejaculatory ducts. Unlike a vasectomy, which is permanent, Vasalgel could be reversed by flushing the polymer out with another injection, leaving sperm open, free, and available to do their job once more. If Vasalgel proves successfuly in human trials, couples in long-term relationships could enjoy sex without the hassle of condoms — and the adverse side effects and expenses of the female pill. 'Revolutionizing' Birth Control? If Vasalgel, or something like it, becomes widespread, then unwanted pregnancies — which occur at rates of 80 to 90 percent in women younger than age 19 — could also drop significantly. Females would no longer be under pressure to ask their partners to wear condoms or to take the pill themselves. Men, likewise, could find a quick and easy solution to having frequent sex without having to worry about babies. So if this becomes a birth control revolution of sorts, everyone is happy, right? Probably not big pharmaceutical companies, who hope to maintain female birth control pill sales and will most likely put up a fight to keep their businesses afloat. These companies make their money off a pill that must be taken every day and thus replenished; this cycle keeps the cash coming in. As Samantha Allen writes on The Daily Beast, “Why sell a flat-screen television to a man, after all, when you can rent one to a woman for a decade?” A single injection contraceptive could create a barrier for female pill business. One of the ways that current birth control pill companies might fight back is through advertising the other potential health benefits of pills, such as claiming they relieve period-related issues like cramps or headaches. In 2009, however, the Food and Drug Administration (FDA) cracked down on the popular pill Yaz, which advertised that it could also cure pimples or PMS symptoms, in addition to preventing pregnancy. But instead of helping other health issues, female birth control pills are more likely to cause adverse side effects, including headaches, dizziness, breast tenderness, nausea, bleeding, decreased libido, mood swings, and depression. In addition, birth control pills have been shown to slightly increase your risk of stroke, blood clots, high blood pressure, heart attacks, and liver tumors — especially among smokers. While this doesn't mean that female birth control users are damaging their health, it simply means that a potential male contraceptive could be safer than ever before — for both parties. There is yet another thing to consider: Will Vasalgel also reduce condom use, and thus protection against sexually transmitted diseases? If a man gets a Vasalgel injection and stops using condoms for birth control, he might have a higher chance of getting or spreading STDs. But male birth control is still a few years away — and trials will first need to be completed in humans. So for now, condoms are probably your one-stop shop for protection against both pregnancy and STDs. ||||| Find Your Answers Here! How does Vasalgel™ work? Vasalgel is a polymer hydrogel that is injected into the vas deferens (the tube sperm swim through) and blocks or filters out sperm. The quick procedure is similar to No-Scalpel Vasectomy (NSV), except the doctor injects the vas with gel, instead of cutting it. Does it stop ejaculation? Vasalgel has no effect on orgasm or ejaculation, and seminal fluids will still be released (just not with sperm!). Does Vasalgel have the same possible side effects as vasectomy? Two common concerns regarding vasectomy are the development of sperm granulomas and pressure buildup. However, only a small percentage of men who have had a vasectomy experience chronic pain (1-2% according to the American Urological Association). Our current understanding of Vasalgel is that fluids can pass through the gel, but sperm cannot. This will likely reduce the incidence of back-pressure. Sperm granulomas are formed when the vas deferens is severed in a vasectomy and sperm leak into surrounding tissue. Since injection of Vasalgel does not involve cutting the vas deferens, this should not be an issue. How is Vasalgel pronounced? It’s “VAH-zuhl-gel” or “VAY-zuhl-gel”, your choice—even our team can’t agree! It’s named after the vas deferens. Is Vasalgel the same as RISUG®? They’re similar, but no. Although Vasalgel and RISUG® are based on the same concept of using a polymer gel injected into the vas deferens, the formulations are not the same. And RISUG has been developed and tested in India over multiple decades, while Vasalgel is being developed in the United States to conform to the latest FDA and international codes of production and safety. Does Vasalgel destroy sperm as they pass by? Our understanding is that Vasalgel works by blocking or filtering out sperm. In the past, RISUG (a different product) was described as working by shredding sperm by an electrical charge process as they went past the contraceptive that lined the walls of the vas deferens. Vasalgel makes no such claims. Is Vasalgel reversible? How is that done? The idea is to develop a fully reversible long-acting male contraceptive, and recently-completed rabbit studies showed rapid restoration of sperm flow. This was accomplished by flushing the Vasalgel from the vas deferens with an injection of sodium bicarbonate (baking soda) solution. Additional preclinical studies are underway to further test the methods and efficacy of reversibility in larger animals. Until reversibility studies are done in men, Vasalgel should be thought of as a vasectomy alternative. When can I get Vasalgel? We want to get Vasalgel on the market as soon as possible, but all the proper efficacy and safety testing needs to be completed. Vasalgel is currently undergoing animal testing, product qualification and safety testing. Human trials are expected to start in 2016 (small trial) and 2017 (larger trials). If everything goes well and with enough public support, we hope to get Vasalgel on the market as early as 2018. How expensive will Vasalgel be? Vasalgel’s developer is committed to making it affordable and widely available—close to cost in low-income countries, and less than current long-acting contraceptives in the U.S.—but until the process is further along we won’t know exactly how much it will cost. It’ll have to cost enough to make the company sustainable, but the goal is for it to cost a day or two’s average wages in wealthy countries, not a week’s wages— $800 or more!—like current long-acting contraceptives (IUDs) for women in the U.S. It is likely that the cost for the doctor visit will be more than for the product. We’ll also work to get it covered by insurance. Will there be an age limit on using Vasalgel? Once it is on the market, Vasalgel will be available like vasectomy and other contraceptive options. However, reversibility evidence will be important for men who may want children in the future. Men’s sperm count declines with age, so freezing sperm as a backup is also an option for men who want to make extra sure they can have children in the future. How can I get into clinical trials? A small trial on men who were planning vasectomy anyway is expected to start in 2016, but the larger clinical trial won’t likely start until 2017. With thousands of men waiting to hear, it’s going to be tricky for the clinicians supervising the trial to decide who can participate! Sign up for the A small trial on men who were planning vasectomy anyway is expected to start in 2016, but the larger clinical trial won’t likely start until 2017. With thousands of men waiting to hear, it’s going to be tricky for the clinicians supervising the trial to decide who can participate! Sign up for the email list to stay informed. Where will clinical trials be? We don’t yet know where the first trials will be held. Sign up for the We don’t yet know where the first trials will be held. Sign up for the email list and we’ll let you know as soon as we know! How will subjects for trials be chosen? The first clinical trials will likely be limited to men who are okay with potential irreversibility (i.e. don’t want any more children), since the clinicians won’t be able to promise reversibility until a reversibility study is later done. For all trials, the clinicians supervising the trial will determine selection criteria and final study participants. We’d like to be able to say that the longest-time fans or earliest donors or biggest donors would get priority, but unfortunately it may not work that way—we may not have much choice in what regulators permit. Sign up for the The first clinical trials will likely be limited to men who are okay with potential irreversibility (i.e. don’t want any more children), since the clinicians won’t be able to promise reversibility until a reversibility study is later done. For all trials, the clinicians supervising the trial will determine selection criteria and final study participants. We’d like to be able to say that the longest-time fans or earliest donors or biggest donors would get priority, but unfortunately it may not work that way—we may not have much choice in what regulators permit. Sign up for the email list to get updates as it takes shape. And donate to help us get it to market, so everybody has access! Can I just go to India to get RISUG®? Unfortunately not! RISUG is not yet on the market in India, and clinical trials of RISUG are only for Indian men who live near the study sites. There is a list of clinical trial sites in India on the RISUG page at NewMaleContraception.org. If you live near one of those cities in India, you might be in luck! But otherwise, Vasalgel is your best bet and we hope for your support. Are results from research on Vasalgel published? Preclinical studies in rabbits were completed in late 2013 and results are being prepared for publication. It takes a while for scientific research to go through the peer review and publication process, but we anticipate publication of rabbit studies in 2015 in open-access journals. Be sure to sign up for our Preclinical studies in rabbits were completed in late 2013 and results are being prepared for publication. It takes a while for scientific research to go through the peer review and publication process, but we anticipate publication of rabbit studies in 2015 in open-access journals. Be sure to sign up for our email list to get summaries of study results and announcements of publications. How can I help get the word out about Vasalgel? Share the news about Vasalgel with friends and colleagues; “like” us on Facebook; and sign the nonprofit Male Contraception Information Project’s Share the news about Vasalgel with friends and colleagues; “like” us on Facebook; and sign the nonprofit Male Contraception Information Project’s petition to let funders and policy-makers know that there is a demand for male contraceptives. Then stand up and be counted: Sign up as a supporter of the new Male Contraception Initiative advocacy organization. Finally, if you see any stories online with inaccuracies about Vasalgel, correcting those in the story’s comments section is an area where we could really use help! What options do I have while waiting for Vasalgel? The options aren’t great, but The Male Contraception Information Project has a description of some of the least-bad current ones, including better IUDs for women and a DIY method for men: The options aren’t great, but The Male Contraception Information Project has a description of some of the least-bad current ones, including better IUDs for women and a DIY method for men: “While you wait”. Can I invest in Vasalgel? Can I make a donation? Vasalgel is being developed as a “social venture” (designed to make enough profit to be sustainable, but not make a killing). The primary goal is to make an affordable, effective male contraceptive widely available, so there’s no opportunity for getting rich quick—this is not the next Microsoft stock! Also, our format does not allow us to sell stock on the market. However, you can donate to the venture’s nonprofit parent, Vasalgel is being developed as a “social venture” (designed to make enough profit to be sustainable, but not make a killing). The primary goal is to make an affordable, effective male contraceptive widely available, so there’s no opportunity for getting rich quick—this is not the next Microsoft stock! Also, our format does not allow us to sell stock on the market. However, you can donate to the venture’s nonprofit parent, Parsemus Foundation , to help keep the project afloat! You’ll find the donation link on each of Vasagel’s pages. And we are seeking socially-minded donors/investors of $50,000 or more (accredited investors and investment funds)—so if you know of anybody in that category who would like to see this succeed, please spread the word! Why doesn’t a pharmaceutical company fund the development of Vasalgel? Big pharma experimented with repurposing its female contraceptives for male use, but has not remained interested in male contraception since that approach failed—perhaps because it is more lucrative to sell ongoing hormonal birth control to women. Big pharma already has most of the market in developed countries, and selling a method to women’s partners would cannibalize existing sales. Smaller companies are often scared off by the liability or just don’t have the money. In addition, a pure for-profit company might make the price so high as to reduce access. Vasalgel’s development is being supported by Parsemus Foundation as a “social venture” to ensure low costs and wide availability—so we have to be careful about whom we choose as partners. However, as development progresses, we will seek other social-minded organizations to help us take it to the next level. Why doesn't Vasalgel use Kickstarter to raise funds? Crowdfunding is a great idea for Vasalgel. Kickstarter says they will not accept this type of project (too medical) even though supporters petitioned, but IndieGoGo should be a better fit. We’ll be looking to crowdfund in 2015 to help us prepare for upcoming clinical trials, and building awareness for the project in the meantime. How effective is Vasalgel? We expect that Vasalgel will be as effective as a vasectomy. In a one-year rabbit study, we saw no sperm, starting shortly after implantation, which is a very good sign. We don’t know yet how many years the effect will last for Vasalgel; upcoming research will help produce those answers. Can Vasalgel be used in women? It is certainly possible that Vasalgel could be used in the Fallopian tubes to block the egg from passing through on its way to the uterus. While there has been some experimental work in this area, our focus is on getting Vasalgel to market for men, since there are currently only two contraceptive options for men (vasectomy and condoms). We hope that in the future, this line of research can be followed up to result in a nonhormonal contraceptive option for women, too! Does Vasalgel prevent HIV? No, it’s not likely to stop the spread of HIV, since quite a bit of HIV lives in the seminal fluid and only about a third of HIV lives on the sperm. So it will be most appropriate for committed couples, or as a backup to condoms. To support research on a method that could reduce HIV transmission, check out the No, it’s not likely to stop the spread of HIV, since quite a bit of HIV lives in the seminal fluid and only about a third of HIV lives on the sperm. So it will be most appropriate for committed couples, or as a backup to condoms. To support research on a method that could reduce HIV transmission, check out the Clean Sheets Pill. Why are animal studies needed? Regulatory agencies require a number of steps in the process of approving a new medicine or treatment, and some can only be accomplished with animal models. However, the Parsemus Foundation (which supports Vasalgel research) is also involved in animal welfare, and cannot accept current U.S. research animal care and housing standards in good conscience. Thus for studies that are absolutely required, we are working to “make change within the system” by raising the bar on animal care and showing research facilities that there is another way to do things (and that people are willing to pay for it). The foundation requires, even in the U.S., that animal studies be conducted under the strict European animal welfare standards and follow the recommendations of the UK National Centre for the Replacement, Refinement, and Reduction of Animals in Research. In addition to making their lives as comfortable as possible, animals are adopted out whenever possible. We hope to have your support in paying for these improvements! We have already seen a difference, with some facilities adopting the improvements for other animals in their facility too. It is not a perfect solution, but there is no other way to get humans a new contraceptive option. For more information, check out the Regulatory agencies require a number of steps in the process of approving a new medicine or treatment, and some can only be accomplished with animal models. However, the Parsemus Foundation (which supports Vasalgel research) is also involved in animal welfare, and cannot accept current U.S. research animal care and housing standards in good conscience. Thus for studies that are absolutely required, we are working to “make change within the system” by raising the bar on animal care and showing research facilities that there is another way to do things (and that people are willing to pay for it). The foundation requires, even in the U.S., that animal studies be conducted under the strict European animal welfare standards and follow the recommendations of the UK National Centre for the Replacement, Refinement, and Reduction of Animals in Research. In addition to making their lives as comfortable as possible, animals are adopted out whenever possible. We hope to have your support in paying for these improvements! We have already seen a difference, with some facilities adopting the improvements for other animals in their facility too. It is not a perfect solution, but there is no other way to get humans a new contraceptive option. For more information, check out the Research Requirements for Animal Welfare. Can Vasalgel be used in dogs and cats? Probably, but our first priority is getting Vasalgel developed for human use. In addition, since it does not change hormones, Vasalgel cannot substitute for pet neuter (hormone elimination is necessary to stop behavior such as roaming in dogs and spraying in cats). The demand would be limited to those seeking a reversible, non-behavior-changing option. However, the Parsemus Foundation (which supports the work on Vasalgel) also funds research on nonsurgical sterilization options for domestic animals – including Probably, but our first priority is getting Vasalgel developed for human use. In addition, since it does not change hormones, Vasalgel cannot substitute for pet neuter (hormone elimination is necessary to stop behavior such as roaming in dogs and spraying in cats). The demand would be limited to those seeking a reversible, non-behavior-changing option. However, the Parsemus Foundation (which supports the work on Vasalgel) also funds research on nonsurgical sterilization options for domestic animals – including calcium chloride , a well-studied and very affordable option for cats and dogs that is available for use now, worldwide, for about a dollar a dose. Do you work with or support spay/neuter organizations? Please spread the word about Calchlorin nonsurgical pet neuter! For hormone-sparing options for pets that are available now, see our page at Hormone-Sparing Male Sterilization ||||| Vasalgel, a reversible form of male birth control, just took one step closer to your vas deferens. According to a press release from the Parsemus Foundation, a not-for profit organization focused on developing low-cost medical approaches, Vasalgel is proving effective in a baboon study. Three lucky male baboons were injected with Vasalgel and given unrestricted sexual access to 10 to 15 female baboons each. Despite the fact that they have been monkeying around for six months now, no female baboons have been impregnated. With the success of this animal study and new funding from the David and Lucile Packard Foundation, the Parsemus Foundation is planning to start human trials for Vasalgel next year. According to their FAQ page, they hope to see it on the market by 2017 for, in their words, less than the cost of a flat-screen television. So how does Vasalgel work? It is essentially a reimagining of a medical technology called RISUG (reversible inhibition of sperm under guidance) that was developed by a doctor named Sujoy Guha over 15 years ago in India, where it has been in clinical trials ever since. Unlike most forms of female birth control, Vasalgel is non-hormonal and only requires a single treatment in order to be effective for an extended period of time. Rather than cutting the vas deferens—as would be done in a vasectomy—a Vasalgel procedure involves the injection of a polymer contraceptive directly into the vas deferens. This polymer will then block any sperm that attempt to pass through the tube. At any point, however, the polymer can be flushed out with a second injection if a man wishes to bring his sperm back up to speed. The Parsemus Foundation’s messaging on Vasalgel has focused on making the technology appealing to men. In a New York Times op-ed published this year, Elaine Lissner of the Parsemus Foundation pitches the product to “a 20-something or 30-something man, out on the dating market” who is worried about the effectiveness of the pill, given how many women forget to take pills during any given cycle. This pitch, too, is a plea for help. The Parsemus Foundation has to rely on donations and crowdfunding in order to bring male birth control to the market. Long-term treatments like Vasalgel are much less appealing to potential funders in the pharmaceutical industry who, as they observe, would much rather “sell pills to men’s partners every month.” Why sell a flat-screen television to a man, after all, when you can rent one to a woman for a decade? In other words, the medical industry’s investment in the multibillion-dollar female birth control industry might block men’s access to male birth control just as effectively as Vasalgel would block their sperm. But a contraceptive polymer like Vasalgel would be a major medical innovation for more than just the man about town looking to copulate without consequence. In fact, male birth control could be the next major medical advance in women’s health, as strange as that idea seems. If the use of polymer contraceptives were to become widespread, male birth control would completely transform the ways in which we understand sexual and reproductive health. Ever since men started wrapping animal intestines around their penises hundreds of years ago, we have been approaching birth control as a way of temporarily preventing fertilization inside a woman’s body. But what if we haven’t been able to see the forest through the ovaries? What if we could use polymer contraceptives like Vasalgel to block sperm at the source, rather than implementing expensive, convoluted, and potentially harmful contraceptive countermeasures inside women’s bodies? If Vasalgel were to become as widespread and inexpensive as the Parsemus Foundation expects, unintended pregnancies could be substantially reduced. According to the Center for Disease Control, nearly half of pregnancies in the United States are unintended. That figure rises to 80 percent of all pregnancies among women age 19 and younger, and to 90 percent below age 15. The physical, financial, and emotional toll of an unintended pregnancy can be immense. As a report from the Guttmacher Institute notes, the average cost of an abortion is $485, which “pose[s] a major financial burden for women seeking these services,” who are often lower income. Not all unintended pregnancies are unwanted, however, and given the fact that modern birth control has deep roots in Planned Parenthood founder Margaret Sanger’s belief in eugenics, the benefits of male birth control for lower-income families in particular should not be overemphasized. Even if we set the prevention of unintended pregnancies aside, however, the potentially deleterious side effects of female birth control are enough to justify the implementation of Vasalgel on their own. As WomensHealth.Gov notes, side effects of the birth control pill include an increased risk of heart disease, high blood pressure, blood clots, nausea, irregular bleeding, and depression. Less common methods of contraception like diaphragms and sponges can cause the rare and life-threatening toxic shock syndrome (TSS). Injections like Depo-Provera can cause bone loss and the use of intrauterine devices (IUDs) can potentially cause rips or tears in the uterus itself. It would take a commercial announcer a full minute of speed-reading to list off all the risks of every form of female birth control. Interrupting ovulation and fertilization is a complex process that requires a degree of hormonal regulation, often impacting other areas of a woman’s health. But as luck would have it, you don’t have to tamper with testosterone in order to block sperm. It might seem as if men are unstoppable sperm machines, especially given the fact they produce 1,500 of them per second. But because sperm are as fickle as they are plentiful, technologies like Vasalgel and RISUG need not interfere with the production of sperm itself in the same way that female birth control often interferes with ovulation. Like the Little Dutch Boy walking by a dike on the brink of bursting, Vasalgel can simply plug up the vas deferens and stop an entire sea of sperm from crashing through. It promises to be a parsimonious solution to the age-old problem of preventing unwanted pregnancies. This is nothing short of Occam’s razor for your testicles. While the way Vasalgel works inside a man’s body might be simple, its cultural impact would be complex. The Religious Right, in particular, has grown accustomed to a world in which regulating access to birth control means regulating women’s bodies, rather than men’s bodies. Although the Affordable Care Act began offering women no-to-low-cost contraceptive coverage in 2010, the Supreme Court’s now-infamous Hobby Lobby ruling this summer allowed “closely-held corporations” to offer health insurance plans without contraceptive coverage. The Hobby Lobby ruling is already being used to try to undermine Obamacare’s contraceptive requirement altogether. This week, Missouri state Representative Paul Wieland’s lawsuit against the U.S. Department of Health and Human Services went to the Eighth U.S. Circuit Court of Appeals. The court will consider whether or not it is constitutional for “closely-held corporations” to be able to opt out of contraceptive coverage while states like Missouri cannot. Lost in all of this legal conflict, however, is the fact that Hobby Lobby, of course, still covers vasectomies. But what if vasectomies were cheap, non-invasive, fully reversible, and as widespread as the female birth control pill? Would businesses like Hobby Lobby begin to object to them? If Vasalgel became popular and affordable enough to surpass female birth control, it would put the Religious Right’s opposition to contraception to the test. As The New York Times reported in 2012, many on the Religious Right justify their opposition to some forms of birth control by equating them with abortion because they “prevent the implantation of a fertilized egg in the uterus.” But if men’s bodies became the primary site for birth control, would religious leaders shift their rhetoric and take issue with a technology like Vasalgel on the grounds that it prevents life on a massive scale? Or do debates about life only have meaning when they take place over women’s bodies? If the Parsemus Foundation’s optimistic timeline for the release of Vasalgel holds true, we may be forced to confront these questions sooner than expected. In the meantime, men, prepare for the possibility that you may soon take over primary responsibility for contraception from your wife or girlfriend. The future of birth control is coming and soon it might be inside of you.

– There may be another birth control option headed our way, and the guys will get to take the lead on this one. The Parsemus Foundation has tested an injectable, non-hormonal polymer contraceptive on male baboons that appears to successfully prevent pregnancy in females, Medical Daily reports. The procedure, which requires just one Vasalgel injection for long-lasting effects, also seems to be reversible and is hopefully headed into human trials next year, with a possible market date of 2017. The Daily Beast explains the process: Instead of snipping the vas deferens as a vasectomy does, the contraceptive is shot directly into the reproductive tube; the polymer then keeps sperm from entering. To reverse it, another injection can flush out the polymer. The method could prove useful to "a 20-something or 30-something man out on the dating market," according to a post in the New York Times by a foundation official. But it won’t likely be embraced by pharmaceutical companies, which bank on women taking "the pill" long-term, notes Medical Daily. At least one Jezebel commenter isn't optimistic about Vasalgel's appeal: "Something tells me that dudes will not be too keen on the injection aspect of this." (A future birth-control chip for women could last 16 years.)

Amazing, just amazing how our septuagenarian (soon to be octogenarian) sheriff plays the media -- both national and local -- like a two-bit plastic ocarina. Well, usually, his handlers do it for him. In this case, it was Chad Willems of Summit Consulting Group, the sleaze who cooked up the anti-Rick Romley ads and got Joe's new bath sponge, Bill Montgomery, past Romley in the GOP primary for Maricopa County Attorney. Seems Willems played the role usually assigned to Joe's chief shill Lisa Allen, and planted this notion in the head of some schmuck from CNN: That an Arpaio trip to New Hampshire signaled his interest in running for the highest office in the land in 2012. ||||| 6 years ago Sheriff Arpaio is considering a 2012 bid. Washington (CNN) – "America's Toughest Sheriff" Joe Arpaio passed on running for governor earlier this year, but the Arizona lawman who has become a national figure for his tough stand on illegal immigration is not closing the door on a presidential run in 2012. Arpaio, the controversial sheriff of Maricopa County, heads to the early presidential proving ground of New Hampshire Sunday to headline the Nashua Republican City Committee lunch. "I am honored by this invitation to speak to the largest local Republican Party organization in the great state of New Hampshire," Arpaio said in a statement. "As a native New Englander, I'm looking forward to visiting this state that historically chooses who our next President will be." Listen: CNN's Mark Preston and Dick Uliano discuss Sheriff Arpaio's potential run for president. http://podcasts.cnn.net/cnn/services/podcasting/audio/politicalnotebook/pn0909.mp3 Chad Willems, Arpaio's political adviser, said that the sheriff is "not going back to test the waters," but did acknowledge that "People just don't go to New Hampshire if they are not interested in these things." Willems went on to highlight Arpaio's ability to raise money, the fact that he is often sought out by the national media and "is well known throughout the country." "He enjoys being sheriff, but he has been asked by and urged by so many people, thousands of people call and write or email him each week saying, 'Run for president, run for president,' " Willems said. Arpaio earned his nickname for his strict policies towards prisoners and recently has been engaged in a battle with the Obama administration over the issue of illegal immigration. It will be a homecoming of sorts for Arpaio, who was born across the border in Springfield, Massachusetts. He also was a Drug Enforcement Administration official in New England in the 1970s. Arpaio joins a long list of Republicans such as former Massachusetts Gov. Mitt Romney, Minnesota Gov. Tim Pawlenty, former Alaska Gov. Sarah Palin, former Pennsylvania Sen. Rick Santorum, former House Speaker Newt Gingrich and Mississippi Gov. Haley Barbour, among others, who are expected to seriously consider a bid for the GOP presidential nomination.

– The headlines have been cropping up in the RSS feeds of political junkies: Sheriff Joe Arpaio—the self-anointed tough guy in Arizona who doesn't like illegal immigrants—is going to New Hampshire Sunday and pointedly not ruling out a 2012 presidential run. CNN rounds it up here. All this coverage makes Stephen Lemons marvel at the Phoenix New Times: "Amazing, just amazing how our septuagenarian (soon to be octogenarian) sheriff plays the media—both national and local—like a two-bit plastic ocarina." Lemons has seen it time and time again in his home state. Arpaio toys with a run for governor, teases the media, soaks up the attention, then withdraws from consideration. "And so once more, with all the fake coyness of an aged divorcée on the make, Arpaio and his minions float his name for a candidacy the hapless alter kocker has no intention of pursuing. All because the jefe likes to see his name scribbled in news articles, typed up online, and bandied about on the TeeVee."

malnutrition is a common problem in patients with chronic obstructive pulmonary disease ( copd ) , and its prevalence rates are 30 - 60% for inpatients and 10 - 45% for outpatients . low body weight and low fat - free mass ( ffm ) have been recognized as unfavorable prognostic factors in patients with copd , and survival is reportedly only 2 - 4 years in severe patients who are lean and have a forced expiratory volume % in one second ( fev1% ) < 50% . it has also been reported that copd patients with body mass index ( bmi ) < 20 kg / m are at higher risk of acute exacerbations than those with bmi 20 kg / m . in patients with copd , energy insufficiency due to decreased dietary intake caused by appetite loss associated with diminished general physical activity , a tendency toward depression , or dyspnea while eating is speculated to contribute to undernutrition . conversely , enhanced energy expenditure due to the increased work of breathing may also contribute to undernutrition . as the third major cause of undernutrition in patients with copd , the effects of humoral factors such as inflammatory cytokines , adipokines , and hormones on nutrition have been identified . a meta - analysis revealed weight gain and improved grip strength in patients with copd receiving nutritional supplement therapy . in the cochrane review updated in 2012 , the results of a meta - analysis of data from 17 randomized controlled trials revealed that nutritional supplement therapy induced body weight recovery and increased the ffm index with consequently improved exercise tolerance ( 6-minute walking distance ) in undernourished patients with copd . the results also provided evidence for a certain ameliorative effect of the therapy on inspiratory and expiratory muscle strength and health - related quality of life ( st . george 's respiratory questionnaire ) . a systematic review and meta - analysis demonstrates that nutritional support in copd results in significant improvements in a number of clinically relevant functional outcomes . registered dietitians should provide medical nutrition therapy ( mnt ) for patients with copd that focuses on preventing and treating weight loss and other comorbidities . mnt is especially important for patients with copd along with the following conditions : disease onset < 40 years of agefrequent exacerbations ( 2 per year ) despite adequate treatmentrapidly progressive disease course ( decline in fev1 , progressive dyspnea , decreased exercise tolerance , unintentional weight loss)severe copd ( fev1 < 50% of predicted value ) despite optimal treatmentneed for oxygen therapyonset of comorbid illness ( osteoporosis , heart failure , bronchiectasis , lung cancer)possible indication for surgery disease onset < 40 years of age frequent exacerbations ( 2 per year ) despite adequate treatment rapidly progressive disease course ( decline in fev1 , progressive dyspnea , decreased exercise tolerance , unintentional weight loss ) severe copd ( fev1 < 50% of predicted value ) despite optimal treatment need for oxygen therapy onset of comorbid illness ( osteoporosis , heart failure , bronchiectasis , lung cancer ) possible indication for surgery as in the studies presented , nutritional support is important in copd . the patient had a history of numerous hospital treatments for acute exacerbation of copd and had been maintaining his condition on home o2 ( 1 - 1.5 l ) therapy for shortness of breath . the patient underwent lung volume reduction ( lvr ) on the right upper lobe ( rul ) on august 15 , 2012 , had a valve removed from the existing rul , and underwent lvr on the left upper lobe on 2012 - 12 - 18 . after the lvr , the dyspnea worsened and performance was maintained at a level that only allowed movement around the house . the dyspnea worsened 4 - 5 days prior to the hospital visit and reached a severe level on the day the patient visited the emergency room ( december 27 , 2013 ) . after receiving intravenous treatment of levofloxacin and methyl prednisolone , the patient was admitted to the general ward ( gw ) . immediately after admission , the patient was transferred to the intensive care unit with drowsy mentality , and for 5 days after admission , 1600 kcal was administered via enteral tube feeding through an l - tube . when the patient became alert , the patient was transferred back to the gw on january 10 , 2014 and the diet was switched to an oral soft diet . however , due to low consumption , 2 bags of medical food supplement were prescribed starting on january 21 , 2014 . on january 24 , 2014 ( 27 days after admission ) , nutrition management was requested due to a continued low oral intake . this process is shown in figure 1 . at the time of the first nutritional training on january 24 , 2014 , the patient 's height and weight were 157.5 cm and 40.8 kg , bmi was 16.8 kg / m , and percentage of ideal body weight was 75.8% , indicating that the patient was severely underweight . the patient 's usual weight was 49 kg , and the patient had experienced an extreme weight loss of 14% during the 1 month . the patient 's triceps skinfold measurement was 60% and mid - arm muscle circumference was 79% , figures accompanied by loss of both fat mass and ffm . no bioelectric impedance analysis ( bia ) or bone mineral density ( bmd ) measurements were taken , and no parenteral nutrition , medical food supplement ( encover ) , or additional nutritional supplements ( vitamins , omega-3 fatty acids ) were prescribed . the patient was a senior who lived alone without a caregiver and had diminished masticatory function that made chewing foods difficult despite dentures . although the patient did not have dysphagia , the patient had constipation but showed normal bowel movements or frequent small amounts of stool . despite complaints of severe fatigue and dyspnea , the patient maintained a 3-meal - a - day diet and showed no changes in diet patterns . the patient tended to eat mainly rice and leave other foods nearly untouched , and the patient 's daily consumption consisted of 1,500 kcal , including 45 g of protein ( c : p : f = 75:12:13 ) and one packet of soymilk and an oral nutrition supplement . during the first nutritional education session , the diagnosis was determined to be severe malnutrition as a result of chronic disease . the nutrition diagnosis and intervention are shown in table 1 . at the first f / u 3 days later , the patient expressed at the interview , " i take breaks during the meal and finish everything including the side dishes . if i snack , i can not eat much during the meal " . with no significant changes in bowel movements , however , although the patient previously showed an activity level of barely being able to go to the washroom , the patient started walking around the ward supported by a walker . the patient demonstrated a diet exceeding the targeted nutritional requirement , but the patient 's activity level increased . since the patient 's oxygen saturation was well maintained , the patient has not received a f / u after the measurement of 1/9 pco2 44.3 mmeq / l ( normal range , 35 - 45 ) , and no adverse effects of the excessive energy supplementation were observed . hence , the nutritional requirement was reconsidered and increased , and the continuous maintenance of meal intake was encouraged . another department suggested that if the current oral intake level is maintained , the nutritional supplement drinks should be discontinued . the nutrition diagnosis and intervention contents at the first follow - up encounter are shown in table 2 . at the f / u 13 days later , the patient expressed at the interview , " i eat all that was provided , but it seems that the quantity of meals got smaller the last couple of days . in terms of feces , it is not diarrhea , but the frequency of bowel movement is similar " . since february 7 , 2014 , due to the change in prescription to the regular diet , the patient 's dietary satisfaction decreased . the patient 's weight was maintained at 42.2 kg with no changes , and the activity level was maintained at the walking level since the use of the walker . however , a slight increase in albumin and improved complete blood count indicators were observed ; thus , any changes to the consistent diet maintenance were observed through objective indicators . therefore , nutritional intervention was once again performed to ensure consistent diet maintenance and the patient was put on a high protein diet again . the nutrition diagnosis and intervention contents at the second follow - up encounter are shown in table 3 . at the time of discharge 1 week later , the patient 's weight had increased to 44.8 kg and laboratory findings improved , demonstrating the positive effects of active nutritional support . at the time of the first nutritional training on january 24 , 2014 , the patient 's height and weight were 157.5 cm and 40.8 kg , bmi was 16.8 kg / m , and percentage of ideal body weight was 75.8% , indicating that the patient was severely underweight . the patient 's usual weight was 49 kg , and the patient had experienced an extreme weight loss of 14% during the 1 month . the patient 's triceps skinfold measurement was 60% and mid - arm muscle circumference was 79% , figures accompanied by loss of both fat mass and ffm . no bioelectric impedance analysis ( bia ) or bone mineral density ( bmd ) measurements were taken , and no parenteral nutrition , medical food supplement ( encover ) , or additional nutritional supplements ( vitamins , omega-3 fatty acids ) were prescribed . the patient was a senior who lived alone without a caregiver and had diminished masticatory function that made chewing foods difficult despite dentures . although the patient did not have dysphagia , the patient had constipation but showed normal bowel movements or frequent small amounts of stool . despite complaints of severe fatigue and dyspnea , the patient maintained a 3-meal - a - day diet and showed no changes in diet patterns . the patient tended to eat mainly rice and leave other foods nearly untouched , and the patient 's daily consumption consisted of 1,500 kcal , including 45 g of protein ( c : p : f = 75:12:13 ) and one packet of soymilk and an oral nutrition supplement . during the first nutritional education session , the diagnosis was determined to be severe malnutrition as a result of chronic disease . at the first f / u 3 days later , the patient expressed at the interview , " i take breaks during the meal and finish everything including the side dishes . if i snack , i can not eat much during the meal " . with no significant changes in bowel movements , however , although the patient previously showed an activity level of barely being able to go to the washroom , the patient started walking around the ward supported by a walker . the patient demonstrated a diet exceeding the targeted nutritional requirement , but the patient 's activity level increased . since the patient 's oxygen saturation was well maintained , the patient has not received a f / u after the measurement of 1/9 pco2 44.3 mmeq / l ( normal range , 35 - 45 ) , and no adverse effects of the excessive energy supplementation were observed . hence , the nutritional requirement was reconsidered and increased , and the continuous maintenance of meal intake was encouraged . another department suggested that if the current oral intake level is maintained , the nutritional supplement drinks should be discontinued . the nutrition diagnosis and intervention contents at the first follow - up encounter are shown in table 2 . at the f / u 13 days later , the patient expressed at the interview , " i eat all that was provided , but it seems that the quantity of meals got smaller the last couple of days . in terms of feces , it is not diarrhea , but the frequency of bowel movement is similar " . since february 7 , 2014 , due to the change in prescription to the regular diet , the patient 's dietary satisfaction decreased . the patient 's weight was maintained at 42.2 kg with no changes , and the activity level was maintained at the walking level since the use of the walker . however , a slight increase in albumin and improved complete blood count indicators were observed ; thus , any changes to the consistent diet maintenance were observed through objective indicators . therefore , nutritional intervention was once again performed to ensure consistent diet maintenance and the patient was put on a high protein diet again . the nutrition diagnosis and intervention contents at the second follow - up encounter are shown in table 3 . at the time of discharge 1 week later , the patient 's weight had increased to 44.8 kg and laboratory findings improved , demonstrating the positive effects of active nutritional support . this article is a case report of a patient with copd . during a total of 50 days of hospitalization , 3 nutrition education sessions were provided after the first 30 days . the nutritional status at the time of the first nutrition education was at an extreme weight loss of 14% in 1 month along with severe malnutrition with drastic damage to the body muscles and fat . movement was difficult , and the patient was dependent on oxygen for respiration . as a result of chewing difficulties due to tooth defects , approximately 1,600 kcal of nutrition consisting mainly of rice and drinks was consumed ; however , the patient 's diet mainly consisted of carbohydrates due to a lack of knowledge about the need to consume protein . nutrition education was provided to improve the patient 's nutritional status ; as part of the treatment , the patient was educated on the methods of nutritional supplement intake as well as increasing the calorie and protein intakes . changes to the patient 's dietary intake and improvements in the nutritional indicators were collected via direct interview and electronic medical records after 3 days ( second nutrition education session ) and 10 days ( third nutrition education session ) . after the intervention , the energy and protein consumption in the patient 's diet increased , improvements in the nutritional indicators ( weight , laboratory data ) were observed , and above all , an improved activity level that enabled movement was observed . we have tried to adhere to copd mnt in stages prior to the nutrition education . however , some parts of the nutrition assessment guideline were impractical , and a difference in the effects of the practical method suggested by the nutrition intervention for a more effective diet were recognized . furthermore , the shortcomings of the current nutritional management provided to patients with copd were evident . the first shortcoming is related to the difficulty assessing quality of life ( qol ) . for the average patient who is not a participant of a study , it is impractical to assess qol using the available tools and the limited amount of time and human resources . in addition , the guideline suggests an assessment of the ability to prepare and consume a meal according to a patient 's nutritional requirements . however , in this case , the patient was a senior who lived alone and used home oxygen . in the first month of hospitalization , the patient was in no condition to benefit from nutritional intervention . second , the bia of patients with copd who are not research participants can not be assessed , and the need for bmd assessment is not well recognized and can not be assessed . third , it was difficult to use frequent small amounts of medical food supplements for this patient . with snack consumption , since the patient 's nutritional requirements were well exceeded with meals alone , the active use of medical food supplements was not suggested ; rather , a tailored method of nutritional intervention was required . in addition , there were practical difficulties in recommending vitamins and omega-3 fatty acids due to the patient 's low recognition of their benefits and increase in medical expenses . although our patient met 6 of 7 nutrition management target categories as suggested by copd mnt , the patient 's status of malnutrition continued to progress 1 month after admission ; further , nutrition management was requested , demonstrating the need for an active nutrition management starting at the time of admission . with this patient in particular , the lack of nutrition intervention at the time of admission was disappointing , especially given the significant increases in the patient 's food consumption following the nutrition education sessions and dietary changes . significant improvements in physical and functional outcomes as a result of nutritional support have been reported in systematic reviews and meta - analyses . likewise , in this case , improvements in weight , laboratory data , and motor abilities were observed . to achieve a more effective nutrition intervention in the future , systematic nutrition management , continuous data reporting , and the use of an interdisciplinary team approach

chronic obstructive pulmonary disease ( copd ) is a major cause of disability , and according to statistics from the world health organization , copd is the fourth leading cause of death overall in the face of decades , and expected to be increased . in 2005 , the reported prevalence of copd in korea was 17.2% of adults over the age of 45 . malnutrition is a common problem in papatients with copd . and several nutritional intervention studies showed a significant improvement in physical and functional outcomes . according to the results of previous studies , the nutritional support is important . this is a case report of a patient with copd who was introduced to a proper diet through nutrition education based on the medical nutrition therapy protocol for copd .

the time - differential @xmath18sr experiment was performed with the upgraded alc instrument @xcite located at the @xmath19e3 muon beam line of the proton accelerator of the paul scherrer institute in switzerland . in the @xmath19e3 beam line the muons were `` transversely '' polarized the angle between the muon spin and the muon momentum was @xmath20 . the polarization of negative muons in synthetic diamond was studied in the magnetic field of 14 koe in the temperature range of @xmath21 k. one additional measurement was performed in 3.0 koe at 140 k. the magnetic field at the sample was parallel to the momentum of the incoming muon . the polycrystalline diamond was produced by microwave plasma assisted chemical vapour deposition ( cvd ) in @xmath22/@xmath23 mixtures . the sample with the diameter @xmath24 60 mm was grown on a silicon substrate that was chemically etched after deposition @xcite . the main impurities in the sample were hydrogen ( @xmath2470 ppm ) and nitrogen ( @xmath241.5 ppm ) . other impurities were less than 0.1 ppm . the cylinder - shaped sample d6 with the diameter 25 mm and height 1.3 mm ( thickness 0.427 g/@xmath25 ) for the @xmath18sr study , and two bricks ( samples a and b ) with the dimensions 3x1.5x1.5 mm@xmath26 ( weight 34 mg ) for magnetic measurements were cut using a laser . in the @xmath18sr experiment 85% of the incoming muons stopped in the sample and 15% in the copper holder . as a reference , a graphite sample ( diameter 26 mm and thickness 0.66 g/@xmath25 ) was measured by @xmath18sr under the same conditions as the diamond sample . the time distribution of electrons from the @xmath27 decay was fitted by the function @xmath28 e^{-t/\tau(\rm c)}\\ \hspace{6ex } + n_0({\rm cu})\cdot e^{-t/\tau({\rm cu } ) } + bg\\ p(t)=p_0\cdot e^{-r\cdot t}\cdot { \rm cos}(\omega t + \varphi ) \end{array } \label{polariz}\ ] ] where @xmath29(c ) ( @xmath29(cu ) ) is proportional to the number of muons stopped in the sample ( in the copper holder ) ; @xmath30(c ) ( @xmath30(cu ) ) is the mean lifetime of the muon in the 1s state of carbon ( copper ) ; @xmath31 is the coefficient of asymmetry of the space distribution of electrons taking into account the actual parameters of the spectrometer ; @xmath32 is the muon polarization in the 1s state at @xmath33 ; @xmath34 is the muon spin polarization damping rate ; @xmath35 and @xmath36 are the frequency and the initial phase of the muon spin precession in the magnetic field , and @xmath37 is the time - independent background . the muon polarization @xmath32 in the 1s state of copper is close to zero due to the hyperfine interaction of the muon spin with the spin of the nucleus and due to very fast transitions between the levels @xmath38 and @xmath39 , where @xmath40 is the spin of the copper nucleus and @xmath41 is the muon spin ( see @xcite ) . the behaviour of the muon spin polarization in the reference graphite sample was studied at temperatures 9.6 , 50 , 100 , 200 , and 300 k in a magnetic field of 14 koe . it was observed that in graphite the muon spin polarization and the frequency of the muon spin precession do not depend on temperature : @xmath42/p_0(300~{\rm k})\lesssim 0.06\pm 0.08 $ ] and @xmath43/\omega(300~{\rm k } ) \lesssim ( 6\pm4)\cdot 10^{-5}$ ] ( see also @xcite ) . the relaxation of the muon spin in graphite was not observed within the accuracy of the measurements ( @xmath44 mhz ) . , damping rate @xmath34 and precession frequency shift @xmath45 of the negative muon spin measured in the synthetic cvd diamond sample d6 in the magnetic field of 14 koe.,title="fig : " ] , damping rate @xmath34 and precession frequency shift @xmath45 of the negative muon spin measured in the synthetic cvd diamond sample d6 in the magnetic field of 14 koe.,title="fig : " ] , damping rate @xmath34 and precession frequency shift @xmath45 of the negative muon spin measured in the synthetic cvd diamond sample d6 in the magnetic field of 14 koe.,title="fig : " ] + the results of the measurements on the cvd diamond are shown in fig . [ d6-alc - data ] . in the sample d6 the muon polarization amplitude @xmath32 does not depend on temperature and it is approximately 16 % larger than in the reference carbon sample ( data with larger error bars are results of preliminary measurements , the line is a guide to the eye ) . the muon polarization damping rate depends on temperature as @xmath46 in the range of @xmath47 k ( solid line in fig . [ d6-alc - data ] ) and as @xmath48 in the range of @xmath49 k ( dotted line ) . a strong drop of the damping rate at @xmath50 k and no damping at 300 and 330 k were observed . there is no difference in the damping rate of the muon spin at 140 k in the magnetic field of 3.0 koe compared to 14 koe . generally , the temperature dependence of @xmath34 in sample d6 is similar to that observed earlier for the cvd film samples in 1.5 and 2.5 koe magnetic fields @xcite . as seen in fig . [ d6-alc - data ] , the muon spin precession frequency in the carbon reference sample does not depend on temperature . at room temperature ( @xmath51 k ) the muon spin precession frequency in the d6 sample is close to that in the reference sample : @xmath52/\omega(c ) = ( 1.8\pm0.4)\cdot10^{-4}$ ] . opposite to the theoretical prediction @xcite and to the experimental results in silicon @xcite , a negative shift of the muon spin precession frequency was observed at temperatures below 250 k. the temperature dependence of the frequency shift can be approximated as @xmath53/\omega(300~{\rm k } ) = \delta\omega/\omega \sim -1/t$ ] ( dotted line in fig . [ d6-alc - data ] ) . the negative shift of the muon spin precession frequency may be due to three different reasons : \a ) it may be due to the presence of other paramagnetic defects ( excluding the acceptor centres ) in diamond . the magnetic field at the muon could differ from the external field because of polarization of these paramagnetic defects . for example , n@xmath54 and h1(h2 ) paramagnetic centres were observed in polycrystalline cvd diamond by epr @xcite ; \b ) let us assume that the muonic atom is formed in the @xmath55b@xmath54 state within a time less than 10@xmath56 s and that the transition rate from this state to the equilibrium one ( @xmath55b@xmath57+h ) is smaller than the muon decay rate . in the state @xmath55b@xmath54 the muonic atom has covalent chemical bonds with three nearest carbon atoms , and the fourth carbon atom has an electron with an unpaired spin ( one dangling bond ) . the polarization of this paramagnetic complex in an external magnetic field could result in the negative shift of the muon spin precession frequency ; \c ) negative frequency shift can also be due to polarization of the paramagnetic acceptor centre in the magnetic field if the muonic atom is formed in the ( @xmath55b@xmath57+h ) state in @xmath58 s and the hyperfine interaction in the ac is anisotropic . in the state ( @xmath55b@xmath57+h ) the muonic atom has covalent chemical bonds with all four nearest carbon atoms and a hole localized in the vicinity of ac . the frequency shift of the muon spin precession should be proportional to the susceptibility of the paramagnetic defects or to the susceptibility of the paramagnetic acceptor centres if @xmath59 . therefore , a simple @xmath60 ( curie type ) temperature dependence of the muon spin precession frequency shift is expected . to elucidate the effect of paramagnetic ( magnetic ) defects on the muon spin precession frequency we measured the magnetic susceptibility of our sample . the magnetic moments ( @xmath61 ) of samples a and b were measured in magnetic fields in the range of @xmath62 koe at the temperatures 20 , 100 , and 300 k. the temperature dependence @xmath63 was studied in detail in the magnetic fields of 95.2 oe and 20.0 koe for both samples . the dc magnetization measurements were performed with the quantum design squid magnetometer . the results for both samples a and b are similar within the accuracy of the measurements . the results of the measurements for sample a are presented in fig . [ squid1 ] and in fig . [ squid2 ] . there is evident linear dependence of the magnetic moment on the magnetic field in the range from 0 to 50.0 koe . the susceptibility of the sample was @xmath64 cm@xmath26/g , @xmath66 cm@xmath26/g , and @xmath67 cm@xmath26/g , at the temperatures 20 , 100 , and 300 k , respectively . the value of @xmath68 for the synthetic cvd sample is in agreement with that for natural diamond @xcite . as seen from fig . [ squid2 ] , the magnetic moment of the sample in the 95.2 oe and 20.0 koe magnetic field practically does not depend on temperature in the range of @xmath69 k. only at temperatures below 20 k the magnetic moment slightly increases with decreasing temperature . therefore , the concentration of magnetic impurities ( defects ) in our cvd sample is negligible and can not produce the observed frequency shift . moreover , the muon spin precession frequency shift depends on temperature as @xmath70 in the range of @xmath69 k , where the magnetic moment of the sample is practically constant . the measured values of @xmath32 at different @xmath71 are close to the maximum possible muon polarization in the 1s state of a carbon atom . this means that the muonic atom @xmath55b is formed in one of the chemically bonded @xmath55b@xmath54 or ( @xmath55b@xmath72 + h ) states with a probability close to unity in less than @xmath73 s. it is worth mentioning that the auger transitions of the muon destroy chemical bonds of the muonic atom with neighbouring carbon atoms . theoretical calculations @xcite suggest that the muonic atom in diamond restores chemical bonds and is formed in the @xmath55b@xmath54 state within @xmath74 s. at present we do not have an analytical expression for the relaxation of the muon spin if there is an anisotropic hyperfine interaction in the muonic atom . nevertheless , we may assume that @xmath34 is inversely proportional to the relaxation rate of the magnetic moment of the acceptor centre in both @xmath55b@xmath54 and ( @xmath55b@xmath72 + h ) states . in diamond relaxation of the magnetic moments of @xmath55b@xmath54 and ( @xmath55b@xmath57 + h ) should be attributed to scattering of phonons by these centres . direct , raman , and orbach processes can contribute to phonon scattering , and the temperature dependence of the probability of these processes is very different @xcite . in the present experiment two temperature domains with different temperature dependences of the relaxation rate of the muon spin were observed . thus , we conclude that there is a contribution of two different processes to scattering of phonons at the acceptor in diamond . the dominance of one process over the other reverses at about 80 k. according to the calculations for the acceptor in silicon , the raman process overcomes the direct ( one phonon ) process at @xmath75 k , and the orbach process is negligible below 100 k @xcite . at the magnetic field of 20.0 koe was scaled by 1/210 ] a large negative shift of the precession frequency of the negative muon spin in diamond was found for the first time . simple curie type @xmath76 temperature dependence of the frequency shift was observed . it is not excluded that the muonic atom as an ac forms in the equilibrium ( @xmath55b@xmath57 + h ) state in @xmath77 s and there is an anisotropic hyperfine interaction in ac . the temperature dependence of the relaxation rate of the muon spin evidences that two different processes contribute to phonon scattering by the acceptor centre in the temperature range of @xmath78 k.

polarized negative muons were used to study the behaviour of the boron acceptor centre in synthetic diamond produced by the chemical vapour deposition ( cvd ) method . the negative muon substitutes one of the electrons in a carbon atom , and this muonic atom imitates the boron acceptor impurity in diamond . the temperature dependence of the muon spin relaxation rate and spin precession frequency were measured in the range of @xmath0 k in a transverse magnetic field of 14 koe . for the first time a negative shift of the muon spin precession was observed in diamond . it is tentatively attributed to an anisotropic hyperfine interaction in the boron acceptor . the magnetic measurements showed that the magnetic susceptibility of the cvd sample was close to that of the purest natural diamond . 5 mm 4 mm @xmath1joint institute for nuclear research , 141980 dubna , moscow reg . , russia + @xmath2moscow institute of physics and technology , 141700 dolgoprudny , moscow reg . , russia + @xmath3physik - institut der universitt zrich , winterthurerstrasse 190 , ch-8057 zrich , switzerland + @xmath4natural sciences center of institute of general physics , ras , 119991 moscow , russia + @xmath5paul scherrer institut , ch-5232 villigen psi , switzerland + diamond with its unsurpassed mechanical strength , thermal conductivity , and radiation hardness is a promising semiconductor for particle detectors and electronic components capable of withstanding high heat and radiation loads . great advances have been made over the last years in the technology of manufacturing synthetic single crystal diamond and diamond films @xcite . boron is the only dopant which forms an acceptor centre ( ac ) in diamond with an ionization energy of @xmath6 mev @xcite . the metal - insulator transition occurs at a concentration of @xmath7 @xmath8 of boron atoms @xcite . the epr signal of boron impurities in diamond was observed only for uniaxially stressed samples @xcite , and the electronic state of this acceptor is investigated insufficiently . the possibility of using negative muons to study the behaviour of acceptor impurities in diamond arises from the fact that capture of a negative muon by a carbon atom results in the formation of a muonic atom @xmath9b with an electron shell that is analogous to that of the boron atom . the evolution of the polarization of @xmath10 in the 1s atomic state depends on the interaction of the muon spin with the electron shell of the muonic atom and on the interactions of this muonic atom ( acceptor centre ) with the crystal lattice . providing that the electron shell of @xmath9b has a nonzero magnetic moment ( paramagnetic @xmath9b ) , there is a hyperfine interaction between the muon and the electron shell . the efficiency of the hyperfine interaction depends on the relaxation rate @xmath11 of the magnetic moment of @xmath9b and on the hyperfine interaction constant @xmath12 . according to theoretical calculations @xcite , relaxation of the muon spin and a paramagnetic shift of its precession frequency are expected for @xmath13 . under the assumption of an isotropic hyperfine interaction , the paramagnetic shift should be of positive sign and inversely proportional to temperature . the boron atom as ac in diamond may be in the diamagnetic ( b@xmath14 ) or paramagnetic ( b@xmath14 + @xmath15 ) state . in the latter case a hole is localized in vicinity of the ac . at equilibrium the boron acceptor in diamond is expected to be paramagnetic below @xmath16 k. in earlier experiments @xcite we observed no frequency shift of the muon spin precession in diamond at the level of @xmath17 . the goal of the present experiment was to improve the accuracy of the muon spin precession frequency measurement .

Shannon Johnson Memorial Fund My name is Amanda Archer Morita. I am close friends with Shannon's girlfriend. She is working with Shannon's family in Georgia to make sure Shannon's final wishes are met. Shannon lost his life in the tragic San Bernardino shooting on December 2, 2015. This fund is being set up to cover the expenses incurred from sending his remains back to his home state of Georgia so he can be memorialized with his family. Shannon was a generous, fun-loving soul, who very much loved his family and friends. Shannon was a protector to all of those he loved. Shannon was friendly and easy to know, making friends everywhere he traveled. He loved his job as a Health Inspector. He also loved his community and his fellow co-workers. Shannon lived a quiet and private life in his home in Los Angeles. He loved taking long walks throughout the city, going to concerts, and hanging out at his favorite tattoo parlor. He truly enjoyed laughter, conversation, music, and his pets. Shannon believed in the greatness of love, equality and kindness and treated others accordingly. All who knew him will miss him more than we can ever say, and our thoughts and prayers are with the other families who are grieving the loss of their loved ones. 6.7K SHARES Share Tweet Donate COPY, PASTE & SHARE: https://www.gofundme.com/ShannonJohnson What is GoFundMe? ||||| As bullets rained down on a San Bernardino, California, conference room Wednesday, Denise Peraza huddled underneath an overturned chair, fearing for her life. Squished next to her was a colleague, Shannon Johnson, who Peraza says gave his own life to protect hers. His body served as a shield, and he comforted her during this final heroic act. "Amidst all the chaos, I’ll always remember him saying these three words, 'I got you,'" Peraza, who was shot and is recovering in the hospital, wrote in a statement posted on Facebook. Play Facebook Twitter Embed ISIS Praises San Bernardino Shooters as ‘Martyrs’ 3:04 autoplay autoplay Copy this code to your website or blog Johnson, 45, was one of 14 people killed in the mass shooting at the Inland Regional Center, a state-run facility that serves individuals with developmental disabilities. He worked as a San Bernardino County health inspector, according to Los Angeles Mayor Eric Garcetti. Johnson and Peraza had been sitting next to one another at the table five minutes before Syed Rizwan Farook and his wife, Tashfeen Malik, burst into the room and opened fire. Shannon Johnson was a 45-year-old from the Koreatown area of Los Angeles, and he was killed in the San Bernardino shooting. Mandy Pfifer Related: From Housewife to Killer: The Mystery of San Bernardino Shooter Tashfeen Malik "Wednesday morning at 10:55 am we were seated next to each other at a table, joking about how we thought the large clock on the wall might be broken because time seemed to be moving so slowly," Peraza said. When the shots — more than 60 of them — started, Johnson and Peraza took cover under the table. Johnson kept his "left arm wrapped around me, holding me as close as possible next to him behind that chair," Peraza said. "I believe I am still here today because of this amazing man. This amazing, selfless man who always brought a smile to everyone’s face in the office with his lively stories about his hometown back in Georgia, who will be deeply missed by all," she said, calling Johnson "my friend, my hero." "I'll always remember him saying these three words, 'I got you.'" Peraza was one of 21 people who were injured in the rampage, which authorities are investigating as a terror attack. The extent of her injuries are not clear, although a man who appeared to be her husband, Augusto Peraza, posted on Facebook that she had a bullet in her lower abdomen. Related: More Than 80 Percent of Guns Used in Mass Shootings Obtained Legally NBC News could not immediately confirm that. According to WXIA, the NBC affiliate in Atlanta, Johnson was a talented athlete at Windsor Academy, a private high school in Macon, Georgia. He started working for the San Bernardino County Public Health Department in 2005. A GoFundMe page set up for his family called him a "generous, fun-loving soul."

– Denise Peraza and Shannon Johnson sat next to each other at the Inland Regional Center on Wednesday morning joking that the clock must be broken, as co-workers are wont to do. Minutes later when bullets starting spraying the room meant to host a holiday banquet, both dove under a table with Johnson using his own body to shield his colleague, as the utterly selfless among us are wont to do. "Amidst all the chaos, I'll always remember him saying these three words, 'I got you,'" Peraza, who is currently recovering from at least one gunshot, writes on Facebook. The 45-year-old health inspector succeeded in saving Peraza, but was one of 14 killed in the shooting, reports NBC News. "I believe I am still here today because of this amazing man. This amazing, selfless man who always brought a smile to everyone's face in the office with his lively stories about his hometown back in Georgia, who will be deeply missed by all," writes Peraza. A GoFundMe page set up to return Johnson's remains to his home state has surpassed its $35,000 goal, with $45,000 raised as of this writing; Johnson's girlfriend says any excess after his wishes are met "will be used to spread his message of "I Got You." Read more about those who died here.

while most cases of intestinal malabsorption syndrome are caused by massive intestine resection due to congenital and acquired diseases , a small portion of patients with structurally intact intestines also display intestinal malabsorption syndrome . autoimmune enteropathy ( aie ) , characterized by protracted diarrhea and weight loss , often occurs in infants and young children and can occasionally be observed in adults.1 fewer than 100 adult aie patients have been reported worldwide . mutations in foxp3 , a transcription factor that controls regulatory t - cell development and function , play an important role in its pathogenesis.2 induction of clinical remission has usually required immunosuppressive drugs such as steroids , azothioprine , cyclosporine , and tacrolimus.3,4 some aie patients who do not respond to immunosuppressive therapy can be treated by infliximab.5 interestingly , though malnutrition is common in aie patients , nutrition support has rarely been reported in these special patients . only one paper described total parenteral nutrition ( pn ) in 10 pediatric aie patients . the results showed five of them were weaned off pn , three died of sepsis after a mean period of 18 months ; one underwent total colectomy and one patient is still dependent on tpn for 24 months.6 our paper describes our experience with glutamine - supplemented pn in managing adult patients with aie and its related malnutrition . from april 2006 to january 2012 , four adult patients were identified from ren ji hospital , shanghai jiao tong university school of medicine . all the patients met the criteria for the diagnosis of adult aie : 1 ) adult - onset chronic diarrhea ( > 6 weeks ' duration ) ; 2 ) malabsorption ; 3 ) specific small bowel histology : partial / complete villous blunting , deep crypt lymphocytosis , increased crypt apoptotic bodies , and minimal intraepithelial lymphocytosis ; 4 ) exclusion of other causes of villous atrophy including crohn 's disease , refractory sprue , and intestinal lymphoma ; 5 ) ae and/or ag antibodies . presence of ae and/or ag antibodies is an important diagnostic support , but their absence does not exclude the diagnosis of aie.7 written informed consent was obtained , and the study was approved by the ethics committee of the same hospital . clinical data are obtained at the first admission to our hospital ( table 1 ) . case 2 had undergone enucleation of an ovarian cyst 3 years before the symptoms appeared . the stool routine test was negative without red blood cells , white blood cells , fat drops , and eggs . all immune tests were negative : indirect immunofluorescence antinuclear antibody ( ifana ) , convection immune assay for detection of ena antibody ( cle ) , immunoblot assay for detection of ena polypeptide antibody spectrum ( ibt ) , detection of anticardiolipin antibodies ( acl ) , and double - stranded dna antibodies ( anti - dsdna ) . flow cytometric detection showed that the percentage of cd and cd increased while the percentage of cd and natural killer cells decreased according to the normal range . malnutrition is classified according to bmi and anemia is defined as serum hemoglobin.8,9 severe malnutrition was found in all of the cases . hypocalcemia , hypomagnesemia , and low phosphorus were common in all aie patients ( table 3 ) . a low - calorie ( 15 to 20 kcal / kg / day ) pn was initiated and total calorie increased slowly . it usually took 1 to 2 weeks to achieve the standard goal . a standard pn solution contained a balanced mixture of amino acids , lipids , and glucose in addition to electrolytes , trace elements , and vitamins . the average caloric intake was 20 to 25 kcal / kg / day and the protein amount was 1.2 to 1.5 g / kg / day for the pn prescription . glutamine ( dipeptiven ; sino - swed pharmaceutical ltd . , wuxi , china ) was given to aie patients ( 100 ml / day , every 100 ml containing 20 g ) for 4 weeks followed by a 2-week break , a cycle which was repeated when pn lasted for more than 6 weeks ( fig . 1 ) . then if the frequency of defecation decreased ( to 3 times per day ) and quality improved ( soft and formed stools were achieved ) , when en increased , pn decreased accordingly . if the oral diet met 60% of the daily calorie goal , pn was stopped . each patient was supplemented orally with 250-ml ensure ( 250 kcal ; abbot laboratories ltd . , abbot park , il , usa ) and two probiotics capsules ( a mixture of viable , lyophilized bifidobacterium , lactobacillus acidophilus , and enterococcus faecalis , each capsule containing 0.510 colonies ) three times a day when en started . nutritional indexes did improve significantly in three cases , but not in case 2 ( table 3 ) . pn - associated liver disease ( pnald ) was found in case 2 when she had received pn for 7 weeks.10,11 the fat emulsion was stopped and drugs ( polyene phosphatidylcholine injection and glutathione injection ) were administered to protect liver function . immune medications were applied in two aie patients who did n't response to glutamine - supplemented pn . immune medications were applied in two aie patients who did n't response to glutamine - supplemented pn . clinical data are obtained at the first admission to our hospital ( table 1 ) . case 2 had undergone enucleation of an ovarian cyst 3 years before the symptoms appeared . the stool routine test was negative without red blood cells , white blood cells , fat drops , and eggs . all immune tests were negative : indirect immunofluorescence antinuclear antibody ( ifana ) , convection immune assay for detection of ena antibody ( cle ) , immunoblot assay for detection of ena polypeptide antibody spectrum ( ibt ) , detection of anticardiolipin antibodies ( acl ) , and double - stranded dna antibodies ( anti - dsdna ) . flow cytometric detection showed that the percentage of cd and cd increased while the percentage of cd and natural killer cells decreased according to the normal range . malnutrition is classified according to bmi and anemia is defined as serum hemoglobin.8,9 severe malnutrition was found in all of the cases . hypocalcemia , hypomagnesemia , and low phosphorus were common in all aie patients ( table 3 ) . a low - calorie ( 15 to 20 kcal / kg / day ) pn was initiated and total calorie increased slowly . a standard pn solution contained a balanced mixture of amino acids , lipids , and glucose in addition to electrolytes , trace elements , and vitamins . the average caloric intake was 20 to 25 kcal / kg / day and the protein amount was 1.2 to 1.5 g / kg / day for the pn prescription . wuxi , china ) was given to aie patients ( 100 ml / day , every 100 ml containing 20 g ) for 4 weeks followed by a 2-week break , a cycle which was repeated when pn lasted for more than 6 weeks ( fig . 1 ) . then if the frequency of defecation decreased ( to 3 times per day ) and quality improved ( soft and formed stools were achieved ) , if the oral diet met 60% of the daily calorie goal , pn was stopped . each patient was supplemented orally with 250-ml ensure ( 250 kcal ; abbot laboratories ltd . , abbot park , il , usa ) and two probiotics capsules ( a mixture of viable , lyophilized bifidobacterium , lactobacillus acidophilus , and enterococcus faecalis , each capsule containing 0.510 colonies ) three times a day when en started . nutritional indexes did improve significantly in three cases , but not in case 2 ( table 3 ) . pn - associated liver disease ( pnald ) was found in case 2 when she had received pn for 7 weeks.10,11 the fat emulsion was stopped and drugs ( polyene phosphatidylcholine injection and glutathione injection ) were administered to protect liver function . immune medications were applied in two aie patients who did n't response to glutamine - supplemented pn . immune medications were applied in two aie patients who did n't response to glutamine - supplemented pn . not surprisingly , severe malnutrition , anemia and deficiency of calcium , phosphate and magnesium were found in all aie patients because of intestinal malabsorption . to resolve the nutritional problem , pn is very important for supplying life - essential micronutrients , vitamins and minerals before intestinal function recovers . if the diagnosis of aie is confirmed , pn should begin immediately to avoid deterioration of nutritional status . secondly , the duration of pn in patients with aie ( in our study , at least 15 days ) was longer than that in patients with other conditions . the prevalence of which is 20% to 75% in patients who require long - term pn.12 one measure to prevent pnald is to start pn in a small amount ( 15 to 20 kcal / kg / day ) and to increase the supply slowly to the goal . a second measure is to modify the pn regimen by reduction of calories and the fat emulsion dose.13 another measure is to initiate en.14 the earlier en began , the less likely was pnald to occur . in aie patients , en need not require fasting because the diarrhea does not respond to complete bowel rest.7 the recovery of intestinal function is the key to treating aie . glutamine , fuel for rapid proliferation of intestinal mucosa cells , is reported to be helpful in promoting intestinal rehabilitation . guo et al.15 reported seven pediatric patients with short bowel syndrome ( sbs ) were treated with growth hormone and supplemental glutamine plus en for 3 weeks . wu et al.16 reported that a 3-week treatment including growth hormone plus glutamine resulted in weight gain and a dramatic decrease in stool output in eight adult patients with sbs . our study showed that glutamine - supplemented pn induced clinical remission without steroids in two patients . steroid and azothioprine were required in patients who did n't response to glutamine - supplemented pn.4,5,7 the limitations of our study were the small number of patients and the lack of a control group . another limitation was that probiotics , which are also considered effective in promoting intestinal rehabilitation , were used in the study ; however , their possibly confounding effects were not evaluated.17,18

to evaluate the effects of glutamine - supplemented parenteral nutrition ( pn ) and probiotics in adult autoimmune enteropathy ( aie ) patients . four adult aie patients were identified from april 2006 to january 2012 . clinical and nutritional data were obtained from the patients ' medical records . glutamine - supplemented pn started immediately when the aie diagnosis was confirmed . the total pn duration was 351 days . according to the pn prescription , the average caloric intake ranged from 20 to 25 kcal / kg / day , and the protein intake ranged from 1.2 to 1.5 g / kg / day . alanyl - glutamine ( 20 g / day ) was administered to aie patients for 4 weeks followed by a 2-week break , and this treatment schedule was repeated when pn lasted for more than 6 weeks . body weight gain and an increased serum albumin level were achieved after pn , and defecation frequency and quality also improved . each patient received oral supplements , 250 ml of ensure and two probiotics capsules ( each capsule containing 0.5108 colonies ) three times a day when enteral nutrition started . three aie patients were successfully weaned off pn , and one patient died of pneumonia . glutamine - supplemented pn and probiotics show promise in managing patients with aie and related malnutrition .

most urethral carcinomas ( ucs ) are associated with invasive bladder tumors.1 however , primary uc occurs and accounts for less than 1% of cases . symptomatology includes obstructive or irritative voiding , and urethral strictures or stenosis.2 in males , ucs primarily occur as squamous cell carcinoma ( scc ) . the presence of different histology subclasses depends on the location in the urethra from which the primary tumor arises.15 symptoms typically occur at the late stage of the disease . thus , most patients have a diagnosis of locally advanced disease and a poor prognosis.2,3 treatment regimens remain controversial,6 with limited cases to allow for consensus . surgical intervention remains the leading form of therapy ; however , approaches are case specific , depending on the location of the primary tumor and the degree of invasiveness.1 while uncommon , ucs have a high mortality rate . most cases are diagnosed once the cancer is invasive , resulting in obtuse presentation of severe symptomatology . a male in his late 40s presented to an emergency department with a perineal abscess , which was surgically debrided and the bladder drained via a suprapubic catheter . one year later , he re - presented with further scrotal edema and abscess formation . the patient was unable to void transurethrally , developing urethrocutaneous fistulae ( watering - can perineum ) through which he voided voluntarily . there was extensive purulent and necrotic tissue involving the scrotum as well as 6.5 cm of bulbar urethral loss . the patient was started on iv antibiotics and a wound vacuum assisted closure ( vac ) was placed to promote healing . the patient underwent a total of four debridement procedures and was maintained on long - term antibiotics , without resolution . approximately six months later , he re - presented with fournier s gangrene and underwent drainage of the scrotal abscess and further debridement of the chronic necrotic tissue . a sample of necrotic scrotal tissue was sent for differential diagnosis , and pathology revealed invasive moderately differentiated urethral scc ( fig . 1 ) . the patient had a 15 pack year history of smoking and a recent history of feeling weak and tired and having dyspnea . the patient described significant pain , stating that his pain ranged from 6 to 9/10 . further staging involved computed tomography ( ct ) and fluorodeoxyglucose positron emission tomography ( fdg pet ) scans , which revealed enlarged bilateral groin lymph nodes ( lns ) ( fig . , there was direct invasion of the inferior pubic ramus and metastatic spread to the left femur intertrochanteric ridge . he had been bedridden because of the large mass and had also developed sacral ulceration . following interdisciplinary consultation , we elected to pursue surgery with the intent of effective palliation and debridement of the necrotic ulcer and chronic sepsis , as there was no evidence of distant lung metastasis . he underwent an aggressive en bloc resection including radical penectomy , complete urethrectomy , radical scrotectomy , bilateral radical orchidectomy , bilateral pelvic lymphadenectomy , bilateral groin dissection , resection of inferior pubic rami with urogenital diaphragm , and en bloc resection of the rectum with permanent end colostomy positioned in the left lower quadrant . postoperatively , in the intensive care unit , the skin graft flap failed , requiring the installation of a new pedicle - based skin graft to the perineum from the opposite limb . after healing , he underwent a left femur hemiarthroplasty for the metastatic deposit in the intertrochanteric region . interestingly , fact - g questionnaire on the quality of life ( qol ) pre- and post - operatively did not reveal a significant change [ pre fact - g 57 ; post fact - g 61 ( minimally important difference 67 points)].7 the en bloc resection revealed a large ( 22 cm maximal diameter ) scc , with lymphovascular and perineural invasion ( fig . the tumor arose from the proximal region of the anterior urethra and involved almost the entire length . the scc tested negative for human papillomavirus ( hpv ) , which was detected using p16 immunohistochemistry , suggesting that the identified condyloma was not the etiology of the scc . after discharge , the patient was followed up by medical oncology for consideration of adjuvant chemotherapy and radiation oncology for palliative radiotherapy . restaging by whole - body fdg - pet scan revealed progression with multiple lung metastasis and recurrent pelvic disease , with left ischial and femoral bone metastases ( fig . despite this , the patient remained optimistic and proceeded with chemotherapy ( seven cycles carboplatin and gemcitabine ) and palliative radiation for the painful bone metastasis . he had increasing leg edema , which was likely associated with progression of ln involvement . he was treated with further chemotherapy ( four cycles cisplatin and fluorouracil ) , which alleviated some symptoms . unfortunately , the patient died of sepsis and metastatic disease two years after initial presentation of a perineal abscess . primary uc is a rare disease that makes up less than 1% of all malignancies.8 three other cases where the primary tumor was mistaken for a urethral abscess and subsequently diagnosed as uc have been reported.911 in two of the cases , the patients had a history of urethral stricture and ongoing infection that were managed with drainage of the abscess and multiple rounds of antibiotics with no resolution , similar to the patient presented in this case report.9,10 in our case , a tissue sample was not taken for differential diagnoses until the patient presented with fournier s gangrene . moreover , the patient s history was significant with the development of spontaneous urethrocutaneous fistulae , delayed presentation ( possibly related to remote living situation ) , and a lifelong history of smoking , potentially affecting wound healing . this delayed presentation with advanced disease , however , is reportedly common for proximal uc , which carries a poor prognosis of 5%15% five - year survival , despite aggressive treatment.1 although hpv is associated with urethral scc,12 it was not the etiologic agent in this case , leaving chronic inflammation as a potential etiologic risk factor . well - known inflammatory conditions that increase a patient s risk for cancer include chronic inflammation and schistosomiasis in bladder scc , barrett s esophagitis in esophageal cancer , inflammatory bowel disease in colorectal cancers , and cholangitis in cholangiocarcinoma ( reviewed by coussens and werb13 ) . distal and proximal ucs have different prognosis.1 it is interesting to speculate that the more distal scc may be hpv related and therefore more amendable to chemoradiotherapy similar to oropharyngeal scc,14 whereas the more proximal are inflammatory related requiring an aggressive surgical approach based on biology and disease extent . in this patient , aggressive demasculinizing surgery took him from a bedridden state to one of ambulation with the ability to receive chemoradiotherapy and possibly prolonged survival . this case highlights the need for a high index of suspicion for cancer in erosive urethral strictures and the need for further multi - institutional research into the etiology , predictive markers , and management of these rare cases .

this male patient presented with a scrotal abscess and urinary obstruction . the patient s history included a perineal abscess and the development of urethrocutaneous fistulae ( watering - can perineum ) . he underwent multiple debridement procedures without resolution . during the fifth debridement for fournier s gangrene , a biopsy revealed invasive squamous cell carcinoma . the patient was bedridden because of the large mass , a wide en bloc resection with lymphadenectomy and reconstruction was performed revealing a large ( 22 cm ) squamous cell carcinoma originating from the urethra . he also received palliative chemoradiotherapy and hip hemiarthroplasty . unfortunately , he succumbed to the disease . given the recognized relationship between inflammation and the development of cancer , it is important to entertain a differential diagnosis of cancer , especially with erosive infections . this case report highlights the all too common late presentation of urethral cancer . interestingly , despite correction of the bedridden state with palliative surgery , the patient did not perceive an improvement in quality of life based on the fact - g questionnaire .

prior to the evolution of protein - based enzymes , primitive cells are thought to have relied on rna enzymes for catalysis . the hypothesis of such an early , rna - dominated stage in the evolution of life is supported by the continued existence of ribozymes in modern biology , and especially by the observation that protein synthesis is catalyzed by the rna component of the large ribosomal subunit . in addition to this evidence , ribozymes obtained by in vitro directed evolution can catalyze a wide variety of reactions , encompassing all of the basic classes of transformations necessary for protocell metabolism and reproduction . however , the origins of rna - based protocells remain unclear , and numerous problems must be solved to establish an understanding of how prebiotic chemical systems gave rise to protocells containing both replicating genomic rnas and functional ribozymes derived from those genomic rnas . one of the central problems faced by the earliest cells is likely to have been the slow and inefficient nature of primordial rna replication . indeed , prior to the evolution of a sophisticated rna replicase ribozyme , protocells may have had to rely on the ambient chemical environment to drive non - enzymatic rna replication . efforts to demonstrate prebiotically plausible rna replication chemistry date back some four decades , but despite recent progress , several obstacles remain . at present , non - enzymatic rna polymerization allows for the partial copying of short rna templates . in model studies , the growing rna primer strand is elongated by addition of ribonucleotides activated with a good leaving group ( e.g. , 2-methylimidazole or hydroxyazabenzotriazole ) . in this paper , we assume that the unsolved obstacles to non - enzymatic rna replication reflect our current lack of understanding , and are not insurmountable hurdles . however , we also expect that primitive , chemically driven rna replication was only marginally sufficient for the emergence of protocells bearing small replicating fragments of rna . we then ask : given such a situation , how could protocells bearing selectively advantageous , heritable ribozyme activities have emerged ? ribozymes with a kcat of greater than 1 min are generally at least 30 nucleotides in length and often 50100 nucleotides long ; the few known ribozymes with a kcat of greater than 1 s are over 100 nucleotides in length . generating rnas of 50100 nucleotides in length by non - enzymatic template - directed polymerization seems like a severe challenge . fortunately , several previous reports have shown that such ribozymes can be reconstituted from shorter oligonucleotides by their assembly into a noncovalent complex that retains good catalytic activity . the minimal length of such oligonucleotides reflects the need for stable base - paired stems as the driving force for complex assembly . if each oligonucleotide is anchored in the complex by two or three stems of 56 nucleotides , with interspersed sequences of similar length forming binding or catalytic sites , then a minimal fragment length of 1525 nucleotides would be reasonable . we , therefore , hypothesize that primitive cells contained a set of genomic oligonucleotides in this size range , all being replicated by non - enzymatic chemistry , with some of these oligonucleotides assembling into complexes with useful catalytic activities . if it were possible for even shorter genomic oligonucleotides to generate functional ribozyme complexes , the constraints on rna replication chemistry would be correspondingly diminished . here we show that functional ribozymes can be reconstituted from oligonucleotides that have been further shortened by 3-truncation . in this scenario , the 3-truncated oligonucleotides assemble into unstable and inactive precursor complexes that are held together by very short unstable terminal stems . non - enzymatic template - directed extension of the oligonucleotide 3-termini , which act as primers , lengthens the initially short and unstable base - paired stems , generating stable complexes with good catalytic activity . such extended oligonucleotides could be removed from the pool of replicating rna fragments , as they would be locked into stable catalytic complexes . non - extended genomic fragments would be easier to replicate , owing to both the comparative ease of copying short rna sequences and the fact that they were not sequestered in stable complexes . this simple mechanism substantially relaxes the requirements for rna replication systems , and it could have facilitated the transition from prebiotic chemical systems to evolving living cells . we studied an aptamer and a cis - acting ribozyme that could each be reconstituted by the assembly of two oligonucleotides into a functional complex , held together in part by terminal base - paired stems . we also studied a second , trans - acting ribozyme consisting of a single oligonucleotide , the active form of which required the formation of a base - paired stem between its 3-terminus and an internal sequence . we then modified the structure of each of these oligonucleotides by shortening the 3-end by 3 or 4 nucleotides ; as a result , the 3-truncated oligonucleotides were unable to assemble into functionally active complexes . however , these shortened oligonucleotides could assemble into transiently stable complexes , in which the oligonucleotide 3-ends formed one or two base - pairs in the nascent stem . configuration , in which the 3-end could be extended by non - enzymatic polymerization , thus generating an extended and , therefore , more stable base - paired stem . in each case , we were able to observe the recovery of ligand binding or catalytic activity following non - enzymatic template - directed primer extension ( figure 1 ) . ( a ) 3-truncated oligonucleotides assemble into an unstable , inactive structure . after extending one or more 3-ends on a template derived from another region of the truncated functional rna , the full - length functional rna folds into a stable and active aptamer or catalyst . ( b d ) schematic diagrams of the aptamer and two ribozyme systems used in this study . we chose to work with this aptamer for an initial proof - of - principle of the hypothesis that 3-truncated oligonucleotides can self - assemble into intermediate structures that can serve as templates for the reconstitution of functional rnas . the free malachite green ligand has very low fluorescence , but its fluorescence increases by several orders of magnitude upon binding to the rna aptamer . in addition , the aptamer and its mode of ligand binding have been studied extensively . nmr studies indicate that the terminal base - paired stems form in the absence of ligand , but the central region of the aptamer folds around its ligand , and it becomes ordered only upon ligand binding . thus , it seemed likely that the ability of the aptamer to fold and bind its ligand could be readily controlled by altering the length of its terminal stems . additionally , this aptamer has been previously deconstructed into two oligonucleotides that can assemble into a functional complex . to demonstrate aptamer stabilization by non - enzymatic template - directed rna synthesis , we modified the previously reported sequences of the two - fragment malachite green aptamer . we first changed the original design of the binary aptamer so that one of the base - paired stems is a four nucleotide gggg / cccc stem ( figure 2 ) ; this aptamer retains full malachite green binding activity . however , if the 3-terminal gggg sequence is shortened to a single g , there is no detectable binding of malachite green . if the 3-terminal gggg sequence is shortened to two or three guanosine nucleotides , malachite green binding is reduced , but not eliminated ( figure s1 ) . in the presence of the activated monomer guanosine 5-monophosphate 2-methylimidazolide ( 2-meimpg ) , non - enzymatic extension of the single 3-terminal g on the cccc template regenerates the gggg / cccc stem and results in a stable , functional aptamer ( figure 3 and figure s1 ) . after a 24 h room temperature incubation of 3-truncated and template strands with 2-meimpg , the measured malachite green binding was comparable to that of the aptamer assembled from two full - length oligonucleotides ( figure 2c ) . this experiment shows that inactive functional rnas , made from oligonucleotides that are truncated at the 3-end , can be converted to a functional form by non - enzymatic template - directed rna synthesis . ( a ) structure and sequence of the malachite green aptamer before and after primer extension . ( b ) one molecule of malachite green binds to each fully assembled aptamer . ( c ) fluorescence of malachite green in the presence of aptamer rna at different concentrations of mg . blue squares , unextended 3-truncated strand plus template strand ; blue triangles , 3-truncated strand plus template after 24 h of rna primer extension with 2-meimpg ; green squares , 3-truncated strand after 24 h extension with 2-meimpg and template strand . each sample contained 0.25 m tris - hcl ph 8.0 , 0.15 m nacl , 2 m malachite green , 1 m each strand of the aptamer . having established that a functional rna aptamer can be generated by non - enzymatic extension of the 3-end of one oligonucleotide on a template region of a second oligonucleotide , we investigated the possibility of generating an active ribozyme from two truncated oligonucleotides , each of which could be extended on the other . we chose the hammerhead ribozyme , which cleaves a substrate strand at a defined cleavage site , for these experiments . we modified a previously reported minimized consensus sequence so that the ribozyme could be reconstituted from two strands , referred to as top and bottom . these strands form a complex held together by two stems flanking the catalytic loop region ( figure 3 ) . ( a ) structure and sequence of the hammerhead ribozyme before and after primer extension . the ribozyme is assembled from top and bottom strands ; each of the strands contains a template region ( blue ) and a primer extension region ( green ) . the 5-end of the top strand is fluorescently labeled with cy3 for page analysis . each panel shows two parallel reactions : samples incubated for 24 h with and without 2-meimpg ( i.e. , with or without primer extension ) . the sequences above the gel panels show starting material in each sample : two hammerhead ribozyme strands , each as either unextended 3-truncated or full - length strand . each sample contained 0.25 m tris - hcl ph 8 , 0.15 m nacl , 2.5 m each rna strand , 50 mm 2-meimpg , 50 mm mgcl2 . 2-meimpg - containing lanes exhibit several minor bands , which are believed to be derived from 2-meim - induced rna degradation . the top strand , which contains the cleavage site , was labeled at its 5-end with cy3 . ribozyme activity was measured by fluorescence - detected polyacrylamide gel electrophoresis ( page ) gel separation of the full - length fluorescently labeled top strand from the shorter , cleaved product . when we mixed full - length top and bottom strands in equimolar proportions and incubated the resulting complex at room temperature , ribozyme activity was evident from the appearance of cleaved product ( 65% product in the reaction incubated with 2-meimpg , figure 3 , and experimental section ) . full - length top strand mixed with truncated bottom strand , and truncated top strand mixed with full - length bottom strand , resulted in weak ribozyme activity in both cases . incubation of the 3-truncated top and bottom strands resulted in no ribozyme activity ( figure 3 ) . we then examined the effect of incubating the above oligonucleotide mixtures with the activated monomer 2-meimpg . in the complexes assembled with 3-truncated oligonucleotides , both strands can act simultaneously as primer and template : the 3-end of the top strand can be extended by up to 3 guanosine residues ( employing the 5-end of the bottom strand as a template ) , while the 3-end of the bottom strand can be extended by up to 4 guanosine residues ( employing the 5-end of the top strand as a template ) . in all cases , incubation with 2-meimpg resulted in extension of the 3-ends of the truncated oligonucleotides and reconstitution of ribozyme activity . in primer extension reactions , if the top 3-truncated strand was incubated with the bottom full - length strand , 64% cleavage yield was obtained ; the top full - length strand incubated with the bottom 3-truncated strand resulted in 33% product , and if both top and bottom strands were 3-truncated , 25% product was observed ( compared to only 5% background cutting activity by mixing both 3-truncated strands without 2-meimpg ) ( figure 3 ) . 3-truncation of the bottom strand is generally more deleterious than that of the top , likely due to the additional base pair present in the complex of the 3-truncated top strand with either bottom strand . encouraged by the above results , we sought to examine whether a trans - acting ribozyme ( i.e. , a ribozyme that catalyzes a reaction between two substrates not covalently bound to the ribozyme ) could be activated in a similar manner . we started with the minimized sequence of a diels alderase ribozyme , which catalyzes a diels alder cycloaddition reaction between a broad range of substrates with very good stereoselectivity . we redesigned the ribozyme , in this case composed of a single oligonucleotide , to end with the sequence 5-ggg-3 , which could pair with the internal sequence 5-ccc-3 ( figure 4a ) . we then constructed a set of truncated versions ending in one or two 3-g residues , which we expected to be less active than the full - length ribozyme . ( a ) structure and sequence of the diels alderase ribozyme before and after primer extension . ( b ) the reaction between n - propylmaleimide and 9-hydroxymethylanthracene , catalyzed by the diels alder ribozyme . ( c ) time course of the diels alder reaction with and without the ribozyme . red squares , full - length ribozyme ; orange circles , 3-truncated ribozyme after 24 h extension with 2-meimpg ; green triangles , nonextended 3-truncated ribozyme ; blue diamonds , uncatalyzed reaction . reaction conditions : 100 mm tris - hcl ph 7.5 , 100 mm mgcl2 , 300 mm nacl , 200 m 9-hydroxymethylanthracene , 1000 m n - propylmaleimide , 10 m rna . ( d ) product region of hplc traces of samples stopped at time 0.5 h , corresponding to the reactions on graph in panel c. detection wavelength , 260 nm ; product peak retention time , 12.5 min . we followed the reaction between the substrates n - propylmaleimide and 9-hydroxymethylanthracene by hplc . the background ( i.e. , uncatalyzed ) reaction , in the absence of the catalyst , resulted in conversion of 11% of the anthracene substrate to product in 30 min , and 26% in 1 h. the truncated ribozyme ending in a single 3-g did not result in any significant increase in product formation , while the full - length ribozyme yielded 72% product in 30 min and 88% in 1 h. a synthetic ribozyme variant ending in two 3-g residues had intermediate activity ( figure s2 ) . in order to assess the ability of non - enzymatic primer - extension to convert the inactive truncated ribozyme ending in a single 3-g residue to an active ribozyme , we incubated the truncated ribozyme with the activated monomer 2-meimpg for 24 h. the resulting extended ribozyme was nearly as effective a catalyst as the full - length ribozyme , converting 65% of substrates in 30 min and 78% in 1 h ( figure 4 ) . our observations indicate that functional ribozymes can be generated from non - functional sets of short rna oligonucleotides by using non - enzymatic template - directed rna synthesis to convert unstable and inactive oligonucleotide complexes into stable active assemblies . we have used three separate model systems to show that inactive sets of 3-truncated oligonucleotides can be converted to active aptamers or ribozymes following incubation with the activated monomer 2-meimpg . in each case , the 3-end of one or more oligonucleotides was extended by non - enzymatic template - directed primer extension , converting a very weakly base - paired stem ( generally a single base - pair ) into a stable base - paired stem consisting of four g : c pairs . as a result , we suggest that the first ribozymes may have originated within protocells in a similar three - step process . first , multiple short rna fragments replicated within protocells by non - enzymatic template - directed rna synthesis . these rnas would have been generated in higher - yield than full - length rnas , owing both to their lowered propensity to fold and the higher efficiency of copying short rnas non - enzymatically . third , non - enzymatic rna copying chemistry ( potentially the same chemistry that generated the initial fragments ) extended the 3-ends of the ribozyme precursor oligonucleotides , using other regions of rna in the transient complex as templates , yielding fully functional stable ribozyme complexes . as a result of such a scenario , short , nonfunctional rnas could afford a protocell vesicle fitness , given their ability to assemble into transient complexes and undergo subsequent primer extension to elaborate these complexes into full - length functional rnas . as we have recently demonstrated non - enzymatic primer extension inside fatty acid vesicles , such a scenario seems highly plausible . additional support for our hypothesis is provided by recent results demonstrating that fe can substitute for mg in functional rnas , suggesting that the low solubility of mg in the presence of certain counterions , such as phosphate , may not have been as problematic as anticipated , given the high availability of soluble iron prior to the great oxidation event . while our system incorporates only 2-meimpg , the presence of the other three nucleotide monomers 2-meimpa , 2-meimpc , and 2-meimpu does not impair aptamer or ribozyme reconstitution ( figures s3 and s4 ) , demonstrating that even prebiotically plausible levels of nonenzymatic replication fidelity allow for functional rna reconstitution via this mechanism . given the enhanced thermal stability of the products of primer extension ( figure s5 ) and increases in aptamer and ribozyme activity with increasing stem length ( figures s1 and s2 ) , it is likely that these rnas develop function as a result of stabilization of critical structural stems . it is also possible that some of the enhanced function observed in the rnas occurs as a result of these lengthened homopolymeric stems directing the rna to assume the correct fold . both such results would occur as a direct result of the extension of truncated stems . our observations have significant implications with regard to two aspects of the evolution of functional rnas in early cells . first , our results suggest a natural way in which genomic rna fragments , which must be replicated to enable heritability , can be shorter than the rnas that actually assemble into functional complexes . multiple previous examples have shown that aptamers and ribozymes can often be reconstituted from relatively short oligonucleotides . this alone shows that primitive rna replication systems , whether chemical or ribozyme - catalyzed , need only be sufficient to copy fairly short pieces of rna . however , since primordial non - enzymatic replication systems are expected to be slow and inefficient , and , in fact , no robust copying system has yet been demonstrated experimentally , it remains useful to consider scenarios in which the length of genomic rnas can be further minimized . our results suggest that genomic rna fragments could be at least 34 nucleotides shorter than functional rna fragments , further ameliorating the difficulty associated with primitive rna replication . thus , the process we describe for synthesis of functional rnas relaxes the requirements for prebiotic rna copying efficiency . the second aspect of primitive rna replication that is facilitated by the scenario outlined above has to do with the conflict between the requirements for a good template as opposed to those of a good catalyst . optimal templates should be completely unfolded , with no internal structure to impede the synthesis of a complementary strand . similarly , a good template should not be sequestered within a stable complex with other oligonucleotides . in contrast , a good ribozyme must have a stable folded structure , and if the ribozyme is generated through the association of two or more oligonucleotides , the resulting complex should also be a stable structure . this conflict is partially resolved through the strategy of assembling functional complexes from sets of relatively unstructured oligonucleotides ; however , in order to allow for uncomplexed templates and functional complexes to co - exist , the affinity of the oligonucleotides for each other must be quite weak . such a loose association could make it difficult to form a structurally well - defined complex , although this deserves closer experimental attention . nonetheless , our observations suggest that nonenzymatic primer - extension may provide a natural way to allow for the co - existence of short unstructured templates , and slightly longer derivative oligonucleotides that form stable , functional complexes . we have previously suggested that randomly positioned 25 linkages , generated as a consequence of non - enzymatic rna replication , could also contribute to the distinction between good templates and good ribozymes . we suggest that the effects of 25 linkages could act synergistically with the effects of non - enzymatic primer - extension to produce distinct sets of genomic and functional oligonucleotides in primitive cells . the reaction conditions we have employed generate predominantly 35 linkages , but the small proportion of 25 linkages produced could have been beneficial in this regard . nucleotide 2-methylimidazolides ( 2-meimpn , where n = g , a , c , u ) were synthesized as previously described . the product of the diels alder reaction used in our studies ( 3 ) was synthesized , for use as a standard , by refluxing 0.625 g ( 3 mmol ) of 9-hydroxymethylanthracene ( 1 ) and 0.390 g ( 2.8 mmol ) of n - propylmaleimide ( 2 ) in 15 ml of dry toluene for 14 h. the product was purified by silica gel chromatography with 1:1 hexane : ethyl acetate , and it was obtained as a yellow solid in 71% yield . h nmr ( 400 mhz , cdcl3 ) : 7.27 ( d , 2h ) , 7.36 ( d , 2h ) , 7.24 ( m , 4h ) , 5.29 ( s , 1h ) , 5.11 ( m , 2h ) , 4.75 ( s , 1h ) , 3.32 ( m , 2h ) , 3.08 ( m , 2h ) , 1.63 ( s , 1h ) , 0.86 ( m , 2h ) , 0.495 ( t , 3h ) . c nmr ( 100 mhz , cdcl3 ) : 177.34 , 177.06 , 142.42 , 142.40 , 139.57 , 139.24 , 127.15 , 127.11 , 126.85 , 126.76 , 125.50 , 124.27 , 123.35 , 122.74 , 60.90 , 49.56 , 48.01 , 46.55 , 45.86 , 40.36 , 20.65 , 11.15 . non - enzymatic rna polymerization was initiated by addition of activated rna monomer(s ) to the mixture of 3-truncated and template oligonucleotides . all reaction mixtures were incubated at room temperature for specified times , desalted using ziptip c18 pipet tips ( millipore ) , and analyzed by tbe the binding of malachite green to the aptamer was measured with a spectramax geminiem fluorescence plate reader ( molecular devices ) with excitation wavelength 610 nm and emission wavelength 670 nm . the malachite green stock solution was mixed with rna top and bottom strands to the final concentration of 2 m malachite green and 1 m of each strand of the aptamer in 0.25 m tris - hcl ph 8.0 , 0.15 m nacl . in rna primer extension reactions , the rna strands were mixed with 2-meimpg to final concentrations of 50 mm 2-meimpg and 5 m each rna strand ( i.e. , 5 m of the rna complex ) in 0.25 m tris - hcl ph 8.0 , 0.15 m nacl , 50 mm mgcl2 . after the reaction samples were eluted from the tip with 1:1 acetonitrile : water , solvent was removed on a speedvac vacuum concentrator , and the rna was dissolved in water . the concentration of the sample was measured using a nanodrop spectrophotometer , adjusted to 2 m of the rna complex , and analyzed as shown above . hammerhead ribozyme reactions were initiated by mixing both rna strands to a final concentration of 2.5 m each strand , in 0.25 m tris - hcl ph 8.0 , 0.15 m nacl , 50 mm mgcl2 . reactions were incubated at room temperature for 24 h. after the reaction , samples were desalted using ziptip c18 pipet tips ( millipore ) and analyzed by tbe the reaction yield was calculated as the percentage of the product band intensity relative to the total intensity of all bands on the gel . the diels alderase reaction was initiated by mixing 9-hydroxymethylanthracene and n - propylmaleimide to final concentrations of 200 m 9-hydroxymethylanthracene and 1000 m n - propylmaleimide , in100 mm tris - hcl ph 7.5 , 100 mm mgcl2 , and 300 mm nacl . the diels alderase ribozyme - catalyzed reactions were performed in the presence of 10 m rna . in rna primer extension reactions , the rna strands were mixed with 2-meimpg to final concentrations of 50 mm 2-meimpg and 5 m each rna strand in 0.25 m tris - hcl ph 8.0 , 0.15 m nacl , 50 mm mgcl2 . reactions were incubated at room temperature for 24 h. after the reaction , samples were desalted using ziptip c18 pipet tips ( millipore ) . samples were eluted from the tip with 1:1 acetonitrile : water , solvent was removed on a speedvac vacuum concentrator , and the rna was dissolved in water . the concentration of the sample was measured using a nanodrop spectrophotometer , the concentration was adjusted to 10 m of the rna complex , and this solution was subjected to the above ribozyme reaction conditions . the reactions were incubated at room temperature for the reported amount of time and analyzed on an agilent 1100 analytical hplc with a varian microsorb - mv 100 - 8 c18 250 4.6 mm column with a gradient of solvent a : 0.1% tfa in h2o , and solvent : b 0.1% tfa in acetonitrile , with uv detection at 260 nm .

the earliest genomic rnas had to be short enough for efficient replication , while simultaneously serving as unfolded templates and effective ribozymes . a partial solution to this paradox may lie in the fact that many functional rnas can self - assemble from multiple fragments . therefore , in early evolution , genomic rna fragments could have been significantly shorter than unimolecular functional rnas . here , we show that unstable , nonfunctional complexes assembled from even shorter 3-truncated oligonucleotides can be stabilized and gain function via non - enzymatic primer extension . such short rnas could act as good templates due to their minimal length and complex - forming capacity , while their minimal length would facilitate replication by relatively inefficient polymerization reactions . these rnas could also assemble into nascent functional rnas and undergo conversion to catalytically active forms , by the same polymerization chemistry used for replication that generated the original short rnas . such phenomena could have substantially relaxed requirements for copying efficiency in early nonenzymatic replication systems .

cytologic and surgical specimens were obtained from nine patients diagnosed with acc or abc from 1998 to 2014 at gachon university gil medical center . of the 2,229 cases of uterine cervix carcinomas during this period , there were four cases of acc ( 0.17% ) and five cases of abc ( 0.22% ) . all cytology specimens were obtained by the routine papanicolaou cervicovaginal smear and the cases were confirmed by surgical specimens obtained from punch biopsy , conization or hysterectomy . of the four of acc cases , the age range of these acc cases was 45 to 76 years old at the time of diagnosis . one acc case was excluded because there were no visible malignant cells on the reviewed cytologic slide . of the five cases diagnosed as abcs , four cases coexisted with squamous cell carcinoma . the age range of these abc cases was 56 to 78 years old at the time of diagnosis ( table 1 ) . conventional papanicolaou smear and liquid based preparation methods were used . of the acc patients , three had undergone conventional smears , and the one case that was excluded had undergone a liquid based preparation . we retrospectively reviewed the cervicovaginal smear slides obtained before surgery after histological confirmation . in all cytology slides , a dp70 digital camera ( olympus , tokyo , japan ) was used to take pictures of tumor cells . 8.4 ( imt i - solution , coquitlam , bc , canada ) was used for measurement of the area , circumference , major axis , and minor axis of nuclei . these parameters were then used to compare the morphological differentiation of the nuclei of the acc and abc in cytology specimens . mann - whitney u - test was used for comparison of numeric data of area , circumference , major axis , and minor axis of the nuclei of acc and abc . differences between acc and abc were considered statistically significant when p - values were less than .05 . initial cytologic diagnoses varied , including squamous cell carcinoma , adenocarcinoma , and other malignancies ( table 1 ) . the overall cytologic features of the three cases included large amount of necrotic debris and tumor diathesis as well as numerous orangeophilic globules in the background . most tumor cells were arranged in three - dimensional overlapping tumor cell clusters , consisting of 40 to 50 tumor cells . rarely , opaque orangeophilic contents were observed in the center of the glandular pattern ( fig . tumors were composed of basaloid cells with indistinct nucleoli arranged in nests with a cribriform appearance , which sometimes had a palisading arrangement in the periphery ( fig . all four cases ( cases nos . 46 and 8) coexisted with squamous cell carcinomas confirmed by surgical specimens . 8 was diagnosed as atypical squamous cells of undetermined significance ( table 1 ) . in reviewed cytology slides of five cases , some clusters of malignant cells showed distinctive features different from those of pure squamous cell carcinoma . tumor cells occasionally presented as single cells , but mostly as three - dimensional clusters . rarely , the tumor cell clusters displayed peripheral palisading ; however , there was no glandular structure formation ( fig . individual cells were small and showed slight variation in size with a variable amount of eosinophilic cytoplasm . nuclei were dense basophilic , hyperchromatic , and sometimes had a fine granular chromatin pattern . punch biopsy was performed in one case , and radical hysterectomy was performed for cure in the others . all cases showed cervical ulceration grossly , without formation of a mass - like lesion . these tumors showed solid tumor cell nests with peripheral palisading or cord like arrangement , and they sometimes formed acini structures without hyaline material . the mean nuclear perimeter was 23.32011.412 m in acc , and 15.9205.664 m in abc . the major axis was 5.6641.537 m and 4.6121.025 m in acc and abc , respectively . thus , acc and abc differed significantly in mean nuclear area , circumference , major axis , and minor axis ( p<.001 ) ( table 3 ) . initial cytologic diagnoses varied , including squamous cell carcinoma , adenocarcinoma , and other malignancies ( table 1 ) . the overall cytologic features of the three cases included large amount of necrotic debris and tumor diathesis as well as numerous orangeophilic globules in the background . most tumor cells were arranged in three - dimensional overlapping tumor cell clusters , consisting of 40 to 50 tumor cells . rarely , opaque orangeophilic contents were observed in the center of the glandular pattern ( fig . tumors were composed of basaloid cells with indistinct nucleoli arranged in nests with a cribriform appearance , which sometimes had a palisading arrangement in the periphery ( fig . all four cases ( cases nos . 46 and 8) coexisted with squamous cell carcinomas confirmed by surgical specimens . 8 was diagnosed as atypical squamous cells of undetermined significance ( table 1 ) . in reviewed cytology slides of five cases , some clusters of malignant cells showed distinctive features different from those of pure squamous cell carcinoma . tumor cells occasionally presented as single cells , but mostly as three - dimensional clusters . rarely , the tumor cell clusters displayed peripheral palisading ; however , there was no glandular structure formation ( fig . individual cells were small and showed slight variation in size with a variable amount of eosinophilic cytoplasm . nuclei were dense basophilic , hyperchromatic , and sometimes had a fine granular chromatin pattern . punch biopsy was performed in one case , and radical hysterectomy was performed for cure in the others . all cases showed cervical ulceration grossly , without formation of a mass - like lesion . these tumors showed solid tumor cell nests with peripheral palisading or cord like arrangement , and they sometimes formed acini structures without hyaline material . the mean nuclear perimeter was 23.32011.412 m in acc , and 15.9205.664 m in abc . the major axis was 5.6641.537 m and 4.6121.025 m in acc and abc , respectively . thus , acc and abc differed significantly in mean nuclear area , circumference , major axis , and minor axis ( p<.001 ) ( table 3 ) . acc and abc are rare , accounting for less than 1% of all tumors of the uterine cervix . acc of the cervix was first described by paalman and counseller in 1949 , while abc of the cervix was first reported as a separate entity in 1966 by baggish and woodruff . while there have been many single or multiple case reports of accs and abcs , few have been reported on the cytologic characteristics of these two rare malignant tumors of the cervix [ 3,6 - 10 ] . while some have posited that these tumors share origin from pluripotent reserve cells , their biologic behavior is quite different : whereas abcs are low - grade tumors with good prognosis , accs are aggressive , with frequent local recurrences or metastasis . therefore , accurate differential diagnosis of these two tumors on cervicovaginal smear is very important . however , to date , there are no reports describing the morphologic differences between acc and abc that allow for sufficient diagnosis by cytology . all these patterns were described in a report by grafton et al . , in which three cases were found , and these overlapping tumor cells were said to resemble endometrial adenocarcinoma cells . in the present study , we found that tumor cells in cases of acc display typical glandular structures , which are hardly seen in cases of abc . this feature was previously mentioned as acinus formation , cribriform pattern , or rosette - like group . the cytologic diagnosis of four of the five abc cases in this study was squamous cell carcinoma . this is not surprising because squamous cell carcinoma or squamous intraepithelial lesions are commonly associated with abc . reported abc cases , the cytologic diagnosis was negative or squamous intraepithelial lesion because of the intact surface epithelium with or without dysplasia or no connection with the epithelium . while necrosis has not been reported as a feature of abc , necrosis was frequently seen in the cervicovaginal smears of our abc cases , which can to be explained by the coexisting squamous cell carcinoma . tumor cell clusters showing peripheral palisading in abc was a characteristic finding in our cases and other reports . glandular structures were found more often in acc , which have also been mentioned in previous reports as specific findings of acc . while these features are meaningful findings in the two different tumor groups , because acc and abc may show similar findings in the histology of surgical specimens , these are not significantly distinguishing points . in our acc cases , glandular structures had opaque orangeophilc content in the lumina , which may be a helpful feature in making a diagnosis of acc on the cervicovaginal smear . the two different tumors in this study showed similar nucleic characteristics including hyperchromasia and indistinct nucleoli . however , we noted that acc and abc have different chromatin patterns . whereas acc had a coarsely granular chromatin pattern , abc was more finely granular . in addition , acc shows a more irregular and angulated nuclear outline than abc ( figs . importantly , the nucleic characteristics in acc and abc were significantly different in area , perimeter , major axis , and minor axis . the ratio of minor axis to major axis was approximately 0.728 in acc and 0.669 in abc , which suggests that the shape of the nuclei is very similar ( i.e. , oval rather than spherical in both tumors ) . however , the nucleic area of acc was 1.684 times larger than that of abc . therefore , careful observation of nuclear size , outline , and chromatin pattern may be useful in reaching correct diagnosis when pathologists confuse acc with abc . the differential diagnosis of uterine cervix tumor is very important . because acc and abc are rare tumors , it is difficult to consider these tumors as part of a differential diagnosis . the most misdiagnosed tumor is squamous cell carcinoma , which commonly occurs in the cervix and is coexistent with abc in many cases . in our institution , the initial cytologic diagnosis was squamous cell carcinoma for five of the eight cases in this study . the cytologic characteristics of squamous cell carcinoma are tumor diathesis in the background , low cellularity with single cells or less commonly aggregated cells . the nuclei show marked variation in size and shape with irregular nuclear membrane and coarsely granular chromatin pattern . however , acc and abc commonly show three - dimensional tumor cell clusters and have relatively small , uniform tumor cells . these distinct features could aid pathologists in making a correct diagnosis of acc or abc . these include small cell carcinoma , endocervical adenocarcinoma , endometrial adenocarcinoma , benign endometrial cells , and benign cervical lesion such as atrophy ( table 4 ) . the purpose of this study was to provide comprehensive information on the cytologic characteristics of acc and abc of the cervix , so that pathologists may consider these two malignant tumors when the cervicovaginal smear shows small round cell clusters . although they show significant difference in nuclear area , circumference , major axis , and minor axis , such difference is not of practical use . however , the size difference of nuclei may be useful . in order to distinguish acc from abc , to summarize , pathologists will need to make careful observation on structure of tumor cell cluster , nuclear size , irregularity of nuclear membrane , and nuclear chromatin pattern , with a possibility of combined lesions in mind .

background : adenoid cystic carcinoma ( acc ) and adenoid basal carcinoma ( abc ) are rare in the uterine cervix . acc is more aggressive than abc , thus accurate differential diagnosis is important . in this study , we identified cytologic features useful in distinguishing these two tumors for diagnosis.methods:three cases of acc and five cases of abc were selected for this study . cervicovaginal smear slides were reviewed retrospectively , and the area , circumference , major axis , and minor axis of nuclei were measured using an image analyzer.results:acc displayed three - dimensional clusters with a small acini pattern . abc displayed peripheral palisading without an acini pattern . the nuclei of acc were more irregular and angulated than those of abc , and the former showed a coarsely granular chromatin pattern . the nucleic area , circumference , major axis , and minor axis were 18.5568.665 m2 , 23.32011.412 m , 5.6641.537 m , and 4.1271.107 m in acc and 11.0174.440 m2 , 15.9205.664 m , 4.6121.025 m , and 3.0880.762 m in the cases of abc . all measured values showed statistically significant difference ( p < .001).conclusions : although the nuclei of both of these tumor types were oval shaped , inferred from the ratio of minor axis to major axis ( 0.728 in acc and 0.669 in abc ) , the area of nuclei was approximately 1.7 times larger in acc than in abc . distinguishing nucleic features , including area , morphology , and chromatin pattern , may be helpful in making a correct diagnosis .

constipation affects 2% to 27% of the adult population1,2 and disproportionately affects females and the elderly.3 constipation symptoms are quite diverse but typically include infrequent bowel movements , hard or lumpy stools , excessive straining , bloating , abdominal discomfort , and/or feelings of incomplete evacuation.4 adult constipation negatively influences health - related quality of life5 and is responsible for a substantial patient and societal economic burden.6 the pathophysiology of constipation is poorly understood and likely multifactorial . primary causes of constipation include intrinsic colonic or anorectal dysfunction , with secondary causes related to organic disease , systemic disease , or medications.7 consequently , a wide variety of prescription and nonprescription medications is available for constipation , encompassing a diverse range of therapeutic targets and mechanisms of action . nevertheless , half of patients remain unsatisfied with available treatment options,8 thereby highlighting the continued therapeutic gap in this patient population . osmotic laxatives are often prescribed as a first - line therapy in the management of constipation in children and adults.9,10 lactitol , produced by hydrogenation of lactose , is an osmotic disaccharide laxative that increases osmotic pressure in the intestinal lumen , resulting in increased fecal volume and stimulation of peristalsis.11 several clinical trials have been conducted on the efficacy and tolerance of lactitol in the treatment of adult constipation . the objective of this systematic review and meta - analysis was to determine the efficacy and tolerance of lactitol in the treatment of adult constipation . we searched medline and embase , with no date or language restrictions , for studies of lactitol supplementation on adult constipation , regardless of study design . we used the search terms importal , lactitol , osmotic laxative , or sugar alcohol combined with bowel , constipat * , gastrointestinal , stool , or transit to identify relevant studies . studies were included if they were published in a peer - reviewed journal , investigated the influence of lactitol supplementation on constipation symptoms , included patients 18 years or older , and reported at least one efficacy or tolerance outcome . studies were excluded if constipation was attributed to surgery , hospitalization , or organic gastrointestinal disease . data were extracted and entered into a prospectively developed database and the entries were confirmed by a second investigator ( ao ) . the following data were extracted : general manuscript information , study design characteristics ( study design , comparison , sample size , constipation definition , lactitol delivery method and dosing schedule , treatment duration , concomitant therapies ) , patient characteristics ( age , sex , body mass index , symptom duration ) , efficacy outcomes ( stool frequency , stool consistency , intestinal transit time , physician- and patient - reported efficacy ) , and tolerance outcomes , including adverse events ( aes ) , ae - related withdrawals , withdrawals for any reason , and serious adverse events ( saes ) . a random - effects meta - analysis model was selected a priori given differences in study design characteristics , lactitol dosage and duration , and patient characteristics among studies . the standardized mean difference ( smd ) and 95% confidence interval ( ci ) was preferentially used to report continuous and interval outcomes due to differences in reporting scales among studies . smd values of 0.2 , 0.5 , 0.8 , and 1.0 represent small , medium , large , and very large effect sizes , respectively.12 we additionally reported the difference in means for weekly stool frequency only , since this outcome was reported in a consistent fashion in most studies . the i statistic was used to estimate heterogeneity of treatment effects across studies with values of 25% , 50% , and 75% , representing low , moderate , and high inconsistency , respectively.13 publication bias was assessed using egger s regression test.14 univariate meta - regression and subgroup analysis were performed to explore the influence of individual moderators on the pre- to posttreatment smd of weekly stool frequency with lactitol . these analyses were not performed for other outcomes or for controlled studies due to the insufficient number of reported treatment effects . all analyses were performed using comprehensive meta - analysis software ( version 2.2 ; biostat , englewood , nj , usa ) . we searched medline and embase , with no date or language restrictions , for studies of lactitol supplementation on adult constipation , regardless of study design . we used the search terms importal , lactitol , osmotic laxative , or sugar alcohol combined with bowel , constipat * , gastrointestinal , stool , or transit to identify relevant studies . studies were included if they were published in a peer - reviewed journal , investigated the influence of lactitol supplementation on constipation symptoms , included patients 18 years or older , and reported at least one efficacy or tolerance outcome . studies were excluded if constipation was attributed to surgery , hospitalization , or organic gastrointestinal disease . data were extracted and entered into a prospectively developed database and the entries were confirmed by a second investigator ( ao ) . the following data were extracted : general manuscript information , study design characteristics ( study design , comparison , sample size , constipation definition , lactitol delivery method and dosing schedule , treatment duration , concomitant therapies ) , patient characteristics ( age , sex , body mass index , symptom duration ) , efficacy outcomes ( stool frequency , stool consistency , intestinal transit time , physician- and patient - reported efficacy ) , and tolerance outcomes , including adverse events ( aes ) , ae - related withdrawals , withdrawals for any reason , and serious adverse events ( saes ) . a random - effects meta - analysis model was selected a priori given differences in study design characteristics , lactitol dosage and duration , and patient characteristics among studies . the standardized mean difference ( smd ) and 95% confidence interval ( ci ) was preferentially used to report continuous and interval outcomes due to differences in reporting scales among studies . smd values of 0.2 , 0.5 , 0.8 , and 1.0 represent small , medium , large , and very large effect sizes , respectively.12 we additionally reported the difference in means for weekly stool frequency only , since this outcome was reported in a consistent fashion in most studies . the i statistic was used to estimate heterogeneity of treatment effects across studies with values of 25% , 50% , and 75% , representing low , moderate , and high inconsistency , respectively.13 publication bias was assessed using egger s regression test.14 univariate meta - regression and subgroup analysis were performed to explore the influence of individual moderators on the pre- to posttreatment smd of weekly stool frequency with lactitol . these analyses were not performed for other outcomes or for controlled studies due to the insufficient number of reported treatment effects . all analyses were performed using comprehensive meta - analysis software ( version 2.2 ; biostat , englewood , nj , usa ) . of 88 potentially relevant articles , 62 were considered irrelevant due to non - constipated patients , no lactitol supplementation group , or article type of review , case report , or correspondence . ultimately , eleven studies,1525 representing 663 distinct patients , were included in the meta - analysis . all studies enrolled adult patients with constipation not attributable to surgery , hospitalization , or organic gastrointestinal disease . the minimum constipation symptom duration was 3 weeks in the study of goovaerts and ravelli18 and 3 days in the study of xu et al.25 mean age ranged from 37 to 84 years , mean body mass index ranged from 20 to 25 kg / m ( reported in five studies ) , and 72% of patients were female ( table 1 ) . of the eleven included studies , five were single - arm studies,15,16,18,21,24 four were randomized controlled trials ( rcts ) comparing lactitol with lactulose,17,19,20,25 one was an rct comparing lactitol with placebo,22 and one was a nonrandomized controlled trial comparing lactitol with stimulant laxatives.23 total sample sizes ranged from 10 to 129 patients among studies . lactitol was administered in powder form in all studies at a median starting dose of 20 g per day ( range : 1040 g per day ) over a median treatment period of 28 days ( range : 7156 days ) . all studies utilized an individualized dosing regimen , which was adjusted over the treatment period according to patient response . median dosing across the treatment period was 20 g per day ( range : 1135 g per day ) . no concomitant therapies were administered in any study , with the exception of laxatives for rescue therapy as needed . lactitol ingestion significantly increased weekly stool frequency compared with baseline ( smd : 1.56 , 95% ci : 1.002.11 , p<0.001 ; figure 2 ) , with a difference in means of 3.8 ( 95% ci : 3.24.3 , p<0.001 ) stools per week . stool consistency also improved over the supplementation period with lactitol ( smd : 1.04 , 95% ci : 0.491.59 , p<0.001 ; figure 3 ) . there was significant heterogeneity for stool frequency ( i=91% ) and consistency ( i=87% ) outcomes with lactitol among studies , with publication bias evident for stool consistency only . four studies reported subjective efficacy assessments.15,18,19,24 overall , 77% ( 209/272 ) of physician assessments and 72% ( 113/156 ) of patients rated lactitol efficacy as good or excellent . compliance with the lactitol supplementation regimen was excellent , with 93% ( 500/539 ) of patients completing the study . approximately one - third of patients ( 173/509 ) experienced an ae ; however , symptoms were generally mild with aes and rarely ( 5% ; 28/539 ) resulted in study withdrawal . two saes ( myocardial infarction and pulmonary embolism ) were reported in a study of 14 elderly ( mean age : 82 years ) patients with multiple comorbidities residing in a long - term care facility.16 the relationship of lactitol use to the saes was not reported . we performed univariate meta - regression to identify predictors of improvement in weekly stools with lactitol . sample size , mean age , percentage of female patients , lactitol mean dose , and treatment duration were loaded into the model . shorter treatment duration ( r=48% , p<0.001 ) , larger sample size ( r=41% , p<0.001 ) , lower mean dose ( r=32% , p<0.001 ) , younger age ( r=30% , p<0.001 ) , and higher percentage of female patients ( r=5% , p=0.03 ) were associated with more frequent defecation with lactitol supplementation . when dichotomizing predictor variables above and below median values for subgroup analyses , all treatment effects remained very large , with no statistically significant differences identified between subgroups . specifically , stool frequency smds were 2.05 for treatment duration < 20 days versus 1.17 for 20 days ( p=0.12 ) , 1.98 for age < 50 years versus 1.23 for age 50 years ( p=0.14 ) , 1.82 for sample sizes 40 versus 1.32 for < 40 ( p=0.41 ) , 1.63 for studies 75% female versus 1.51 for studies < 75% female ( p=0.84 ) , and 1.29 for mean dose 20 g per day versus 1.34 for mean dose < 20 g per day ( p=0.95 ) . overall , lactitol similarly improved stool frequency across subgroups with possible additional benefit in younger adults and with shorter treatment durations . lactitol was slightly more effective than lactulose in increasing weekly stool frequency ( smd : 0.19 , 95% ci : 0.01 to 0.39 , p=0.06 ; figure 4 ) , with a difference in means of 0.3 ( 95% ci : 0.1 to 0.8 , p=0.15 ) stools per week . stool consistency was similar with lactitol and lactulose ( smd : 0.03 , 95% ci : 0.22 to 0.28 , p=0.81 ) ( figure 5 ) . only one study reported comparative product satisfaction assessments.19 physician - assessed efficacy was 60% with lactitol and 64% with lactulose ; patient - assessed efficacy was 60% for lactitol and 56% for lactulose . no statistically significant differences were noted for any tolerance outcome comparing lactitol with lactulose , with odds ratios of 0.81 ( 95% ci : 0.371.76 , p=0.59 ) for aes , 1.19 ( 95% ci : 0.314.61 , p=0.80 ) for ae - related withdrawals , and 0.94 ( 95% ci : 0.263.33 , p=0.92 ) for withdrawal for any reason . no significant heterogeneity or publication bias was identified for any outcome . a single randomized , placebo - controlled clinical trial of lactitol in constipated adults has been performed.22 forty - six elderly patients ( mean age : 84 years ) were randomly assigned to 4 weeks of lactitol or placebo in a crossover design . at baseline , mean weekly stool frequency was 2.40.6 and 11 ( 26% ) of 43 patients reported hard stools . over the 4-week intervention period , stool frequency improved by approximately 2.5 stools per week with lactitol relative to placebo ( p<0.001 ) . stool consistency improved by approximately 0.5 points ( on a four - point scale ) with lactitol relative to placebo ( p=0.001 ) . the incidence of side effects , including flatulence , bloating , abdominal cramps , or diarrhea , was 51% ( 22/43 ) with lactitol and 30% ( 13/43 ) with placebo ( p=0.08 ) . no aes were classified as serious and none led to patient withdrawal from the study . vanderdonckt and ravelli23 conducted a nonrandomized crossover study in which ten elderly patients ( mean age : 75 years ) took stimulant laxatives for 2 weeks followed by lactitol for 4 weeks . lactitol resulted in a higher weekly stool frequency compared with stimulant laxatives ( 2.02.8 , p=0.03 ) . physician - rated efficacy of lactitol was favored over stimulant laxatives in 8/10 patients and lactitol tolerance was favored in 7/10 patients . all ten patients completed the 2-week stimulant laxative phase , but two patients discontinued lactitol due to abdominal discomfort . of 88 potentially relevant articles , 62 were considered irrelevant due to non - constipated patients , no lactitol supplementation group , or article type of review , case report , or correspondence . ultimately , eleven studies,1525 representing 663 distinct patients , were included in the meta - analysis . all studies enrolled adult patients with constipation not attributable to surgery , hospitalization , or organic gastrointestinal disease . nine studies1517,1924 enrolled patients with chronic constipation ( minimum duration > 6 months ) . the minimum constipation symptom duration was 3 weeks in the study of goovaerts and ravelli18 and 3 days in the study of xu et al.25 mean age ranged from 37 to 84 years , mean body mass index ranged from 20 to 25 kg / m ( reported in five studies ) , and 72% of patients were female ( table 1 ) . of the eleven included studies , five were single - arm studies,15,16,18,21,24 four were randomized controlled trials ( rcts ) comparing lactitol with lactulose,17,19,20,25 one was an rct comparing lactitol with placebo,22 and one was a nonrandomized controlled trial comparing lactitol with stimulant laxatives.23 total sample sizes ranged from 10 to 129 patients among studies . lactitol was administered in powder form in all studies at a median starting dose of 20 g per day ( range : 1040 g per day ) over a median treatment period of 28 days ( range : 7156 days ) . all studies utilized an individualized dosing regimen , which was adjusted over the treatment period according to patient response . median dosing across the treatment period was 20 g per day ( range : 1135 g per day ) . no concomitant therapies were administered in any study , with the exception of laxatives for rescue therapy as needed . lactitol ingestion significantly increased weekly stool frequency compared with baseline ( smd : 1.56 , 95% ci : 1.002.11 , p<0.001 ; figure 2 ) , with a difference in means of 3.8 ( 95% ci : 3.24.3 , p<0.001 ) stools per week . stool consistency also improved over the supplementation period with lactitol ( smd : 1.04 , 95% ci : 0.491.59 , p<0.001 ; figure 3 ) . there was significant heterogeneity for stool frequency ( i=91% ) and consistency ( i=87% ) outcomes with lactitol among studies , with publication bias evident for stool consistency only . four studies reported subjective efficacy assessments.15,18,19,24 overall , 77% ( 209/272 ) of physician assessments and 72% ( 113/156 ) of patients rated lactitol efficacy as good or excellent . compliance with the lactitol supplementation regimen was excellent , with 93% ( 500/539 ) of patients completing the study . approximately one - third of patients ( 173/509 ) experienced an ae ; however , symptoms were generally mild with aes and rarely ( 5% ; 28/539 ) resulted in study withdrawal . two saes ( myocardial infarction and pulmonary embolism ) were reported in a study of 14 elderly ( mean age : 82 years ) patients with multiple comorbidities residing in a long - term care facility.16 the relationship of lactitol use to the saes was not reported . we performed univariate meta - regression to identify predictors of improvement in weekly stools with lactitol . sample size , mean age , percentage of female patients , lactitol mean dose , and treatment duration were loaded into the model . shorter treatment duration ( r=48% , p<0.001 ) , larger sample size ( r=41% , p<0.001 ) , lower mean dose ( r=32% , p<0.001 ) , younger age ( r=30% , p<0.001 ) , and higher percentage of female patients ( r=5% , p=0.03 ) were associated with more frequent defecation with lactitol supplementation . when dichotomizing predictor variables above and below median values for subgroup analyses , all treatment effects remained very large , with no statistically significant differences identified between subgroups . specifically , stool frequency smds were 2.05 for treatment duration < 20 days versus 1.17 for 20 days ( p=0.12 ) , 1.98 for age < 50 years versus 1.23 for age 50 years ( p=0.14 ) , 1.82 for sample sizes 40 versus 1.32 for < 40 ( p=0.41 ) , 1.63 for studies 75% female versus 1.51 for studies < 75% female ( p=0.84 ) , and 1.29 for mean dose 20 g per day versus 1.34 for mean dose < 20 g per day ( p=0.95 ) . overall , lactitol similarly improved stool frequency across subgroups with possible additional benefit in younger adults and with shorter treatment durations . lactitol was slightly more effective than lactulose in increasing weekly stool frequency ( smd : 0.19 , 95% ci : 0.01 to 0.39 , p=0.06 ; figure 4 ) , with a difference in means of 0.3 ( 95% ci : 0.1 to 0.8 , p=0.15 ) stools per week . stool consistency was similar with lactitol and lactulose ( smd : 0.03 , 95% ci : 0.22 to 0.28 , p=0.81 ) ( figure 5 ) . only one study reported comparative product satisfaction assessments.19 physician - assessed efficacy was 60% with lactitol and 64% with lactulose ; patient - assessed efficacy was 60% for lactitol and 56% for lactulose . no statistically significant differences were noted for any tolerance outcome comparing lactitol with lactulose , with odds ratios of 0.81 ( 95% ci : 0.371.76 , p=0.59 ) for aes , 1.19 ( 95% ci : 0.314.61 , p=0.80 ) for ae - related withdrawals , and 0.94 ( 95% ci : 0.263.33 , p=0.92 ) for withdrawal for any reason . a single randomized , placebo - controlled clinical trial of lactitol in constipated adults has been performed.22 forty - six elderly patients ( mean age : 84 years ) were randomly assigned to 4 weeks of lactitol or placebo in a crossover design . at baseline , mean weekly stool frequency was 2.40.6 and 11 ( 26% ) of 43 patients reported hard stools . over the 4-week intervention period , stool frequency improved by approximately 2.5 stools per week with lactitol relative to placebo ( p<0.001 ) . stool consistency improved by approximately 0.5 points ( on a four - point scale ) with lactitol relative to placebo ( p=0.001 ) . the incidence of side effects , including flatulence , bloating , abdominal cramps , or diarrhea , was 51% ( 22/43 ) with lactitol and 30% ( 13/43 ) with placebo ( p=0.08 ) . no aes were classified as serious and none led to patient withdrawal from the study . vanderdonckt and ravelli23 conducted a nonrandomized crossover study in which ten elderly patients ( mean age : 75 years ) took stimulant laxatives for 2 weeks followed by lactitol for 4 weeks . lactitol resulted in a higher weekly stool frequency compared with stimulant laxatives ( 2.02.8 , p=0.03 ) . physician - rated efficacy of lactitol was favored over stimulant laxatives in 8/10 patients and lactitol tolerance was favored in 7/10 patients . all ten patients completed the 2-week stimulant laxative phase , but two patients discontinued lactitol due to abdominal discomfort . we performed the first meta - analysis on the efficacy and tolerance of lactitol in the treatment of adult constipation . overall , lactitol supplementation was found to be well tolerated and to improve stool frequency and consistency in constipated patients . the efficacy and tolerance of lactitol for adult constipation were found to be similar to those of lactulose . although excluded from the current meta - analysis , two relevant studies also suggested favorable laxative effects with lactitol for adult constipation attributed to surgery or hospitalization . cop et al26 conducted an rct of lactitol or oral petroleum jelly for recovery of intestinal transit following anal surgery . patients consuming 20 g lactitol per day had a quicker time to first stool after surgery ( 24 versus 39 hours , p=0.002 ) versus those assigned to petroleum jelly and reported more frequent bowel movements over the 7-day postoperative period . pontes et al27 conducted an rct comparing liquid lactulose , crystallized lactulose , crystallized lactitol , and a control in hospitalized patients without reported constipation . all active therapies decreased colonic transit time compared with controls , with the lactulose groups experiencing a slightly greater improvement compared with lactitol . the conclusions of the current meta - analysis differ somewhat compared with those of two earlier systematic reviews,28,29 mainly due to their inclusion of non - peer - reviewed reports , studies with children , or adults with hospitalization- or surgery - related constipation . both of those systematic reviews reported superior efficacy and better tolerance of lactitol over lactulose . based on a systematic review of peer - reviewed manuscripts in adults with functional constipation , we observed a trend for improved stool frequency with lactitol versus lactulose but no differences in other efficacy or tolerance parameters . several authors have reported that the excessive sweetness of lactulose negatively affects patient compliance and that the slightly sweet taste of lactitol is preferred by patients.3032 while several single - arm studies in the current meta - analysis reported excellent patient acceptance with lactitol , no rcts with lactitol or lactulose reported data on taste preference and no statistically significant differences were identified in any tolerance outcome . although lactitol is generally well tolerated up to 40 g per day,33 mild gastrointestinal complaints are common , with a similar frequency to lactulose and a nonsignificantly higher frequency compared with placebo . only 5% of patients discontinued lactitol therapy due to gastrointestinal side effects , with no differences noted between lactitol and lactulose or placebo . the laxative effect with lactitol is attributed to a lowering of colonic ph as a consequence of fermentation by the colonic microbiota , stimulation of peristalsis , and increased osmotic pressure in the intestinal lumen , ultimately resulting in an increase in fecal volume and more frequent defecations.11 although this mechanism of action may result in mild gastrointestinal complaints in some patients , the benefit - to - risk profile of lactitol remains favorable given the significant laxative effect in constipated patients . first , despite the strong efficacy profile of lactitol , the limited number of controlled studies made interpretation of the comparative benefits difficult . although numerous gastrointestinal studies have been recently conducted with lactitol , it is unclear why there is a dearth of recent studies in adult constipation . third , the number of included studies was minimally adequate to execute meta - regressions and subgroup analyses ; therefore , these estimates may be somewhat unstable . fourth , duration of constipation symptoms varied among studies and was occasionally unreported . finally , only two studies administered lactitol for over 4 weeks . therefore , the effects of long - term lactitol use for treatment of adult constipation remain unknown . lactitol supplementation was found to be well tolerated and to significantly improve symptoms of adult constipation . the efficacy and tolerance of lactitol and lactulose were comparable , with a trend for more frequent stools with lactitol . limited evidence suggests lactitol is superior to stimulant laxatives and placebo for relieving constipation symptoms . we recommend additional larger scale rcts to further characterize the effect of lactitol supplementation in this patient population , with recommended comparisons including placebo controls , other osmotic laxatives , fibers , and probiotics .

backgroundconstipation is a common complaint in adults . lactitol is an osmotic disaccharide laxative that increases fecal volume and stimulates peristalsis . in this paper , we present the first meta - analysis on the efficacy and tolerance of lactitol for adult constipation.methodswe searched medline and embase , with no date or language restrictions , for studies of lactitol supplementation on adult constipation . a random - effects meta - analysis was performed on pre- to posttreatment changes in stool frequency and consistency with lactitol among all studies , as well as a comparison of efficacy and tolerance outcomes in randomized controlled trials ( rcts ) of lactitol versus lactulose.resultsa total of eleven studies representing 663 distinct patients were included in the final analysis , including five single - arm studies , four rcts comparing lactitol with lactulose , one rct comparing lactitol with placebo , and one nonrandomized controlled trial comparing lactitol with stimulant laxatives . weekly stool frequency was significantly increased with lactitol compared with baseline ( standardized mean difference [ smd ] : 1.56 , p<0.001 ) . stool consistency also improved over the supplementation period with lactitol ( smd : 1.04 , p<0.001 ) . approximately one - third of patients experienced an adverse event ; however , symptoms were generally mild and rarely ( 5% ) resulted in study withdrawal . in rcts of lactitol versus lactulose , lactitol was slightly more effective than lactulose in increasing weekly stool frequency ( smd : 0.19 , p=0.06 ) . no statistically significant differences between lactitol and lactulose were identified in any other efficacy or tolerance outcome . lactitol demonstrated favorable efficacy and tolerance in individual studies when compared to stimulant laxatives and placebo.conclusionlactitol supplementation is well tolerated and improves symptoms of adult constipation . the efficacy and tolerance of lactitol and lactulose are similar , with a trend for more frequent stools with lactitol . limited evidence suggests lactitol is superior to stimulant laxatives and placebo for relieving constipation symptoms .

Japan's Prime Minister Yoshihiko Noda (5th L) walks in front of Patriot Advanced Capability-3 (PAC-3) land-to-air missiles units as he inspects the Defense Ministry in Tokyo December 7, 2012. Japan's government have deployed PAC-3 interceptor missiles to prepare for the... Japan's Prime Minister Yoshihiko Noda (3rd L) delivers a speech to Japan Self-Defense Forces soldiers in front of the Patriot Advanced Capability-3 (PAC-3) land-to-air missiles unit, at the Defense Ministry in Tokyo December 7, 2012. Japan's government have deployed PAC-3... Members of the Japan Self-Defence Forces stand guard near Patriot Advanced Capability-3 (PAC-3) land-to-air missiles, deployed at the Defense Ministry in Tokyo December 7, 2012. Japan's government have deployed PAC-3 interceptor missiles to prepare for the launch of a North... A member of the Japan Self-Defence Forces stands near Patriot Advanced Capability-3 (PAC-3) land-to-air missiles, deployed at the Defense Ministry in Tokyo December 7, 2012. Japan's government have deployed PAC-3 interceptor missiles to prepare for the launch of a North... Engineers check the top of a rocket sitting on a launch pad at the West Sea Satellite Launch Site, during a guided media tour by North Korean authorities, northwest of Pyongyang, in this file photo taken by Kyodo on April 8, 2012. North Korea's new young leader is using an... A soldier stands guard in front of a rocket sitting on a launch pad at the West Sea Satellite Launch Site, during a guided media tour by North Korean authorities, northwest of Pyongyang, in this file picture taken April 8, 2012. North Korea's new young leader is using an... WASHINGTON The United States is shifting warships into position to track and possibly defend against a planned North Korean rocket launch while urging Pyongyang to cancel its second such attempt this year, the head of the U.S. Pacific Command said on Thursday. Admiral Samuel Locklear, who commands U.S. forces in the Asia-Pacific region, said warships were being moved to the best locations to track the rocket during its launch and flight, which North Korea has set for sometime between December 10 and 22. The United States is watching preparations for the launch "very closely," he told a Pentagon news conference. He said U.S. warships were being moved to monitor the rocket, as they were when Pyongyang attempted a similar launch in April. "It should seem logical that we'll move them around so we have the best situational awareness," he said. "To the degree that those ships are capable of participating in ballistic missile defense, then we will position them to be able to do that." Pyongyang says the launch aims to put a satellite into space. The United States and many other countries view it as a test of a long-range, nuclear-capable ballistic missile that would violate U.N. resolutions and further destabilize the Korean Peninsula. The North Korean launch attempt in April failed. Locklear said the repositioned U.S. ships would help answer a series of questions. "If they do violate the Security Council and launch a missile, what kind is it? What is it about? Where does it go? Who does it threaten? Where do the parts of it ... that don't go where they want it to go, where do they go? And what are the consequences of that?" he said. The admiral said his main concern was reassuring U.S. allies that the United States was effectively monitoring the situation. "We believe it is still contradictory to the U.N. Security Council resolutions ... because of the nature of the type of missile that they will be firing and the implications it has for ballistic-type of activity somewhere down the road and the destabilizing impact that will have on the security environment throughout the region," Locklear said. He said there had been signs that the government of new leader Kim Jong-un would take a more "rational approach" to how it deals with its economy, its citizens and its international relationships. Kim took power after the death of his father, former leader Kim Jong-il, on December 17. The anniversary of his father's death falls during the time frame set by North Korea for the rocket launch. Presidential elections in neighboring South Korea take place two days later, on December 19. Locklear said while there was hope for a shift in North Korea's political direction, Pyongyang was once again poised to violate U.N. Security Council resolutions regarding its nuclear program. "We encourage the leadership in North Korea to consider what they are doing here and the implications on the overall security environment on the Korean Peninsula, as well as in Asia," he said. (Additional reporting by Jim Wolf; Editing by Xavier Briand) ||||| New satellite images indicate that snow may have slowed North Korea's rocket launch preparations, but that Pyongyang could still be ready for liftoff starting Monday. Japanese Prime Minister Yoshihiko Noda, standing by a ground-based Patriot Advanced Capability-3 interceptor, looks back as he speaks during his inspection tour to the Defense Ministry in Tokyo Friday,... (Associated Press) This Dec. 4, 2012 satellite image taken by GeoEye and annotated and distributed by North Korea Tech and 38 North shows the Sohae Satellite Launching Station in Tongchang-ri, North Korea. New satellite... (Associated Press) This Dec. 4, 2012 satellite image taken by GeoEye and annotated and distributed by North Korea Tech and 38 North shows the Sohae launching station in Tongchang-ri, North Korea. New satellite images show... (Associated Press) This Dec. 4, 2012 satellite image taken by GeoEye and annotated and distributed by North Korea Tech and 38 North shows snow covering the Sohae launching station in Tongchang-ri, North Korea, including... (Associated Press) South Korean media reports this week quoted unnamed officials in Seoul as saying North Korea had mounted all three stages of the Unha rocket on the launch pad by Wednesday. But snow may have prevented Pyongyang from finishing its work by then, according to GeoEye satellite images from Tuesday that were scrutinized by analysts for the websites 38 North and North Korea Tech and shared Friday with The Associated Press. The analysis and images provide an unusually detailed public look at North Korea's cloaked preparations for a launch that the United Nations, Washington, Seoul and others say is a cover for a test of technology for a missile that could be used to target the United States. The launch preparations have been magnified as an issue because of their timing: Both Japan and South Korea hold elections this month, and President Barack Obama will be inaugurated for his second term in office in January. North Korea, for its part, says it has a right to pursue a peaceful space program and will launch a satellite into orbit sometime between Monday and Dec. 22. That launch window comes as North Korea marks the Dec. 17 death of leader Kim Jong Un's father, Kim Jong Il. North Korea is also celebrating the centennial of the birth of Kim Jong Un's grandfather, national founder Kim Il Sung. Images from Dec. 1 showed no rocket at the launch pad, but by Tuesday North Koreans were seen working under a dark canvas, according to the analysis by 38 North, the website for the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies, and the North Korea Tech website, which collaborated with 38 North on the report. The analysis contradicts South Korean media reports that the rocket stages were set up by Wednesday. Since the launch pad was empty Dec. 1, and it had taken North Korea four days to erect a similar rocket before a failed launch attempt in April, it should have taken longer for North Korea to prepare the rocket, the websites said. Snowfall on Monday also may have temporarily stopped work at the site, according to the analysis written by Nick Hansen, a retired expert in imagery technology with more than 40 years of national intelligence experience. North Korea has a long history of developing ballistic missiles, but in four attempts since 1998 it has not successfully completed the launch of a three-stage rocket. It has also conducted two nuclear tests, intensifying worry over how its rocket technology could be used in the future, particularly if it masters attaching a nuclear warhead to a missile. A senior South Korean government official told foreign reporters in Seoul on Friday that North Korea has been making technical preparations for a nuclear test and could theoretically conduct one in a short period of time, but that it isn't clear when or if they will test. The official spoke on condition of anonymity, citing government rules. Friday's analysis of the satellite images said North Korea can still be ready for liftoff Monday. Based on its preparations for the April launch, which broke apart shortly after the rocket was fired, Pyongyang has to finish stacking its rocket stages only two to three days ahead of time _ meaning workers could finish by Saturday and still be ready for a launch on Monday, the analysis said. North Korea may have chosen a 12-day launch period, which is more than twice as long as the April period, because it was worried about possible weather complications, the analysis said. "Pyongyang's rocket scientists can't be happy about the increased technical risks of a wintertime test, but certainly appear to have taken every precaution necessary in order to launch the rocket on time," said Joel Wit, a former U.S. State Department official and editor of 38 North. A rocket can be launched during snowfall, but lightning, strong wind and freezing temperatures could stall a liftoff, said Lee Chang-jin, an aerospace professor at Seoul's Konkuk University. North Korea's launch plan is meant to show the world its capability to build missiles, U.S. Pacific forces commander Adm. Samuel Locklear said Thursday. The United States has moved extra ships with ballistic missile defense capabilities toward the region, officials said. Two South Korean destroyers will be deployed in the Yellow Sea in the coming days to track the North Korean rocket, defense officials in Seoul said Friday. They spoke on condition of anonymity because ministry rules bar them from releasing information about defense movements over the phone. The U.S., Japan and South Korea say they'll seek U.N. Security Council action if the launch goes ahead in defiance of existing resolutions. The council condemned April's launch and ordered seizure of assets of three North Korean state companies linked to financing, exporting and procuring weapons and missile technology. On Friday, Japanese Prime Minister Yoshihiko Noda visited a Tokyo military facility to inspect Patriot Advanced Capability-3 missile interceptors being readied to intercept a North Korean rocket if it falls on Japanese territory. The commander of American troops in Japan, Lt. Gen. Salvatore Angelella, said this week that his troops are closely monitoring activity in North Korea as it prepares for the launch. ___ Associated Press writers Matthew Pennington in Washington and Sam Kim in Seoul contributed to this report. ___ Online: 38 North: www.38north.org North Korea Tech: www.northkoreatech.org

– North Korea is planning a rocket launch in the next few weeks, and the US is getting ready: Washington is shifting warships to the best spots to keep an eye on the launch, and perhaps defend against it, Reuters reports. The US is monitoring the run-up to the launch "very closely," says the head of the US Pacific Command. "To the degree that those ships are capable of participating in ballistic missile defense, then we will position them to be able to do that," he noted. The US made a similar move during a failed North Korean rocket launch in April. US monitoring will answer questions about the rocket, adds a Navy admiral, including: "What kind is it? What is it about? Where does it go? Who does it threaten?" While Pyongyang says it's trying to send a satellite into space, other countries, including the US, see the move as a ballistic missile test flouting UN resolutions. Regardless, the AP finds a potential wrinkle in North Korea's ambitions: Satellite images show that snow may have slowed its launch preparations; however, it could still be ready to go on Monday.

here we show that if one uses an isotropic exchange interaction instead of the anisotropic interactions in the teleportation protocol one can also perform adiabatic teleportation . in this case the initial hamiltonian is @xmath90\end{aligned}\ ] ] and the final hamiltonian is @xmath91\end{aligned}\ ] ] where we have expressed these hamiltonians in terms of the encoded operations given in eq . 1 of the main text . these equations show that now instead of two decoupled encoded qubits , the encoded qubits are coupled . however notice that the initial ground state is the @xmath92 eigenstate of @xmath23 and @xmath24 and the final ground state is the @xmath92 eigenstate of the @xmath27 and @xmath28 , just as in anisotropic exchange protocol , but with the signs flipped . further there are no level crossing in a linear ramping between these two hamiltonians , and the gap is a constant @xmath93 occurring at the midpoint of this evolution . thus the adiabatic teleportation protocol caries through for the isotropic exchange . notice , importantly , that the coupling however must be antiferromagnetic . here we provide more details on how to implement the hamiltonian in eq . 4 in the main text using the perturbation theory gadgets of bartlett and rudolph @xcite . in these gadgets , one replaces one of the qubits in a three - qubit interaction by an _ encoded _ qubit across two qubits . since we need two three - qubit interactions , this means that we require two extra qubits in this construction . we label our logical qubits @xmath94 and @xmath95 ( for left and right ) , and encode each into four physical qubits labeled 1 4 . and @xmath95 , each encoded in three physical qubits @xmath96 , where the ancillas facilitate the teleportation as discussed in the main text . blue bars represent @xmath97 couplings , while green triangles represent interactions of the form @xmath98 ( and similarly with @xmath99 ) as in eq . ( [ e : ideal ] ) . ] let s recall eq . 4 , relabeled here as in fig . [ f : ideal ] . the ideal initial hamiltonian is @xmath100 , \end{aligned}\ ] ] where @xmath101 $ ] just means to add the terms which exchange the qubits @xmath94 and @xmath95 . now let s add the ancilla qubits and move to the encoded subspace . the encoded subspaces we are working in are the subspaces spanned by @xmath102 and @xmath103 on qubits @xmath104 and @xmath83 . we can force the joint state of qubits 3 and 4 to lie in this subspace by adding a strong @xmath105 coupling term to the ideal hamiltonian . thus , eq . ( [ e : ideal ] ) can be realized using encoded operators as the following target hamiltonian @xmath106 . \end{aligned}\ ] ] here the encoded operators ( with bars on top ) are @xmath107 for both the left and right qubits and we are assuming that the coupling strengths satisfy @xmath108 . we are free to choose either @xmath109 or @xmath110 for the encoded @xmath111 operation because these operators act equivalently up to multiplication by the stabilizer of the encoded subspace . writing this out in terms of the pauli operators on the physical qubits , we find ( for one such choice of encoded @xmath5 ) @xmath112 .\end{aligned}\ ] ] following bartlett and rudolph , we use the following initial hamiltonian . it is a two - body gadget hamiltonian that simulates the low energy behavior of the above target hamiltonian , and is given by @xmath113 .\end{aligned}\ ] ] the @xmath9 term in this hamiltonian by itself would force the ground state of qubits @xmath104 and @xmath83 to be in the subspace spanned by @xmath102 and @xmath103 as discussed above . the @xmath71 term is now a two - qubit interaction which simulates the four - body term in the target hamiltonian . our desired final hamiltonian is given by @xmath114 .\end{aligned}\ ] ] notice , importantly , that we leave on the interaction which forces qubits @xmath104 and @xmath83 into the encoded subspace during the entire evolution . as usual , our total evolution is given in terms of the scaled time @xmath19 by @xmath115 this evolution is depicted in fig . [ f : gadget ] . we must show that the above adiabatic evolution has high fidelity with the ideal evolution and that the gap is not too small . the fidelity is governed by the overlap of the ground state of @xmath10 with the ground state of the ideal ( encoded ) hamiltonian @xmath116 . . the simulation gadget uses one additional ancilla qubit ( labeled @xmath83 ) per logical qubit . qubits @xmath104 and @xmath83 are bound by strong @xmath117 couplings for the duration of the evolution , as shown by the broad green bars . blue bars represent two - body interactions @xmath118 , while the red horizontal bar represents a @xmath119 coupling . when the coupling strengths are chosen so that @xmath120 , this adiabatic evolution simulates the ideal evolution of eq . ( [ e : ideal ] ) and fig . [ f : ideal ] . the fidelity of the simulation is @xmath121 and the energy gap governing the adiabatic condition is given by @xmath122 . ] in order to analyze this gadget it is useful to perform a change of basis . in particular if one undoes the controlled - phase gate between the ancilla qubits @xmath123 and @xmath124 , then above hamiltonian becomes a sum of terms acting separately on @xmath94 and @xmath95 . since this is a unitary conjugation it does nt change the gap , and we can also find the ground state in this basis and transform back . since the hamiltonian is now decoupled across @xmath94 and @xmath95 , we drop these subscripts now and write the transformed initial hamiltonian as @xmath125 note that the final hamiltonian is unaffected by this transformation , and so we need merely to drop the @xmath94 and @xmath95 superscripts to obtain @xmath126 let s first find the ground state of the initial hamiltonian so we can check the fidelity . we can further simplify things by applying a controlled - not gate from qubit 3 to qubit 2 resulting in @xmath127 in this basis , qubits 1 and 2 completely decouple , and the fidelity depends only on the overlap of this ground state with the bell state @xmath128 on qubits 3 and 4 . we can exactly diagonalize by first transforming to the bell basis . let s define @xmath129 to be our small expansion parameter . then the ground state of eq . ( [ e : twoprimes ] ) on qubits 3 and 4 is given by @xmath130 where the coefficient @xmath131 is @xmath132 expanding in powers of @xmath129 , the fidelity is @xmath133 which is corrected at second order in @xmath134 . now let s compute the gap to see what price we must pay to achieve high fidelity . in the basis where we have applied a controlled - not from qubit 3 to qubit 2 , the final hamiltonian is @xmath135 note that @xmath136 and @xmath137 commute with both the initial and final hamiltonian , corresponding to the encoded quantum information . suppose we work in a basis where this information is in the @xmath22 eigenstate of @xmath136 . then the final hamiltonian simplifies to @xmath138 here we see that qubits @xmath88 and @xmath84 are decoupled from those of @xmath104 and @xmath83 . if one linearly sweeps between these initial and final hamiltonians , one will obtain a minimal gap for each of these evolutions . the smaller of these gaps comes from qubits @xmath104 and @xmath83 . explicitly , the evolution to consider is @xmath139 -s [ \lambda z_3 + \omega ( z_3 z_4)].\ ] ] the gap between the lowest two eigenvalues of this evolution is @xmath140 where @xmath141 using the fact that @xmath142 for @xmath143 we can bound this as @xmath144 we can upper bound the lower equation by @xmath145 , and we can use @xmath146 for @xmath147 to express the gap as @xmath148 this obtains its max at @xmath149 for @xmath150 this yields a bound on the gap of @xmath151 thus we have shown that the initial fidelity with the proper ground state is high @xmath152 , and also that the energy scale which sets the adiabatic condition is set by the perturbative energy scale , @xmath153 . for fault - tolerance we require a fixed accuracy and our results imply that the gadget construction can achieve this , albeit at the cost of the energy gap shrinking and thus a slower adiabatic gate time .

the difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers . here we introduce a simple universal primitive , adiabatic gate teleportation , which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space . notably this construction allows for geometric robustness based upon the control of two independent qubit interactions . further , our piecewise adiabatic evolution easily relates to the quantum circuit model , enabling the use of standard methods from fault - tolerance theory for establishing thresholds . building a quantum computer is a daunting task , so much so that it is not even clear which of a plethora of architectures is the most physically viable . in addition to the standard pulsed implementation of the circuit model of quantum computation ( qc ) , other possible architectures include measurement - based qc @xcite , universal adiabatic qc @xcite , and holonomic qc @xcite . of these , adiabatic qc has recently drawn considerable attention , in part because of its deep connection to computational complexity problems @xcite , but also due to the advantages this model possesses with respect to decoherence and control @xcite . similarly holonomic qc has attracted interest because of the geometric robustness of control in this scheme . motivated by some of the benefits of adiabatic and holonomic qc , we introduce a new model of qc which is a hybrid between the adiabatic , circuit , and holonomic models . this model uses nothing but adiabatic quantum evolution , but instead of using a single interpolation between an initial and final hamiltonian , we use piecewise adiabatic evolutions whose individual parts implement a step in a quantum circuit . we achieve this by introducing a new primitive : adiabatic gate teleportation ( agt ) . our route to agt proceeds by merging two quantum computing protocols : teleportation and adiabatic qc . quantum teleportation is the process of transferring the state of a qubit between two distant parties via the use of an initial shared entangled state and two bits of classical communication @xcite . notably , while teleportation consumes a bell pair @xmath0 shared between the parties , it can end with a bell pair localized to the sender . in adiabatic qc @xcite one adiabatically turns off one hamiltonian while turning on another hamiltonian , dragging the system from the ground state of the initial hamiltonian to that of the final hamiltonian . the initial hamiltonian is chosen such that preparing the system in its ground state can be done efficiently , and the final hamiltonian is chosen so that its ground state is the solution to a computational problem . motivated by teleportation and adiabatic quantum algorithms , we will attempt to adiabatically mimic teleportation . this will lead us to an adiabatic protocol for swapping with a simple control scheme that we call adiabatic teleportation . the main theme of this paper is to use variants on this adiabatic teleportation scheme and the analogy with gate teleportation @xcite to build a universal quantum computer from piecewise adiabatic evolutions . constant - gap piecewise adiabatic evolution has previously been considered in the context of state preparation @xcite and in the context of producing geometric quantum gates from noncyclic adiabatic evolution @xcite . our model is distinguished from these results by achieving universality and geometric robustness with separately controlled interactions , and by its explicit connection to gate teleportation . _ adiabatic teleportation _ our setup uses three qubits . the first qubit is the qubit whose state we wish to transport ( swap ) to the third qubit . the second qubit is merely a mediator , which ( we will see ) is necessary . at the beginning of the computation we construct a system whose ground state has a single bell pair @xmath1 on the second and third qubit . we then adiabatically drag the system to a new hamiltonian whose ground state has a bell pair on the first and second qubit ( again @xmath1 . ) throughout the evolution the lowest energy level , which is two - fold degnerate , remains degenerate . if we encode a single qubit of information into this degeneracy , then after this adiabatic evolution the information in this first qubit will now reside in the third qubit . we choose the initial hamiltonian for our three qubits to be @xmath2 and the final hamiltonian to be @xmath3 where @xmath4 and @xmath5 are single qubit pauli matrices , @xmath6 represents the operator @xmath7 acting on the @xmath8th qubit , and the identity acting on all other qubits and @xmath9 sets the energy scale . the ground state of @xmath10 is two - fold degenerate : we can choose a basis for this space as @xmath11 and @xmath12 . similarly , the ground state of @xmath13 is spanned by @xmath14 and @xmath15 . in other words , initially we can store a qubit of information in the first qubit and in the final system we can store it in the third qubit and both configurations are ground states of their respective hamiltonians . now suppose we adiabatically drag the system between @xmath10 and @xmath13 . for example , we may linearly turn off @xmath10 and turn on @xmath13 so that @xmath16 from time @xmath17 to @xmath18 and @xmath19 is a dimensionless scaled time with scale @xmath20 . ( other interpolation schemes are certainly possible , and indeed this is one of the benefits of using an adiabatic evolution . ) the above evolution moves the information stored in the first qubit to the third qubit , as we now show . let s first define logical qubit operators @xmath21 initially we are in the @xmath22 eigenstate of @xmath23 and @xmath24 . writing @xmath25 in this basis we find @xmath26 since this hamiltonian does not include the first logical qubit , it is untouched by the evolution . this hamiltonian is nothing more than the time dependent sweeping of @xmath23 to @xmath27 and @xmath24 to @xmath28 . evidently this means that if we perform the above evolution slow enough , then , since we start in the @xmath22 eigenstates of @xmath23 and @xmath24 , at the end of the evolution we will be in the @xmath22 eigenstates of @xmath27 and @xmath28 . a minimum energy gap of @xmath29 occurs when @xmath30 . can we figure out what happens to the first qubit under the above evolution ? we can express the first qubit pauli operators in terms of the above logical qubits : @xmath31 and @xmath32 . since we start off in the @xmath22 eigenspace of @xmath24 and @xmath23 , we see that the logical information is really encoded into the first logical qubit . as we have argued above , this qubit is untouched by the evolution . thus when @xmath18 we must have the same logical information in the first qubit , but now be in the @xmath22 eigenvalue subspace of @xmath27 and @xmath28 . now notice that @xmath33 and @xmath34 . thus we see that actually the information from the first qubit has been dragged to the information on the last qubit . because the gap of the above adiabatic quantum evolution is constant , if we evolve the system sufficiently slowly and in a smooth enough manner , then the adiabatic theorem guarantees that we can achieve the above process with a high fidelity . there are numerous adiabatic theorems that can be proven ( see for example @xcite ) which provide guarantees that by making @xmath20 sufficiently large we can increase the probability that the adiabatic evolution will act successfully ( meaning the probability that the system is excited out of the desired subspace is smaller than some constant ) . choosing @xmath35 is sufficient to guarantee a constant error probability below the threshold for fault - tolerant qc @xcite . _ three qubits are necessary _ we have shown that it is possible to swap quantum information between two qubits via a simple adiabatic interpolation between two fixed hamiltonians on three qubits . is it possible to achieve a similar result without the ancilla qubit ? if we wish to simply interpolate between two two - qubit hamiltonians , then no . this does not imply that it is impossible to adiabatically swap two qubits , only that a construction which behaves like the adiabatic quantum algorithm is not possible . we will also see how this null result implies significant benefits over other adiabatic schemes such as holonomic qc . suppose we have two qubits which we wish to swap by adiabatically ramping between an initial hamiltonian @xmath36 and a final hamiltonian @xmath37 . the initial and final hamiltonians are required to be degenerate such that we can store a single qubit of information in these systems . further the initial ( final ) hamiltonian must allow for this degeneracy to reside only in the first ( second ) qubit . without loss of generality , we can pick a basis for the first and second qubit so that @xmath36 and @xmath37 are @xmath38 respectively . now assume that we turn off @xmath36 while turning on @xmath37 . this leads to the hamiltonian @xmath39 , where @xmath40 ( @xmath41 ) is a slowly decreasing ( increasing ) function with @xmath42 and @xmath43 ( @xmath44 and @xmath45 ) . notice , however , that @xmath25 is always diagonal in the basis we picked , and therefore the system can not transform amplitude between these states as required for a swap . it is crucial here that we assume a simple ramping on and off of the hamiltonians . more complicated control schemes lead to holonomic qc which differs significantly from our approach . _ adiabatic gate teleportation _ we have shown how to swap a qubit from the first qubit to the third qubit using adiabatic evolution and now we will show how this can be used to achieve universal qc . first we will show how in the process of swapping we can also apply a single qubit gate by a simple modification of our initial hamiltonian . we label this protocol adiabatic gate teleportation ( agt ) in analogy with how gates can be teleported in the quantum circuit model @xcite . suppose , in analogy with the teleportation of quantum gates , that we apply a unitary rotation on the third qubit on the initial hamiltonian @xmath10 : i.e. consider the initial hamiltonian @xmath46 . such an operation does not change the final hamiltonian , but does change the initial hamiltonian . we can then carry the above analysis forward as before , but now in this changed basis . at the end of the evolution we end up with the logical qubit dragged to the third physical qubit in a rotated basis . the gap remains @xmath47 since the spectrum is unchanged by a unitary conjugation . thus it is possible , using this construction , to perform any single - qubit unitary during the adiabatic teleportation . notice that the rotated @xmath10 will still consist of two - qubit interactions . for example , if we wish to perform a hadmard gate , we can use the same final hamiltonian , @xmath48 , but chang the initial hamiltonian to @xmath49 . it is possible to make different assumptions about how the new , rotated @xmath50 hamiltonian arises physically . we can just assume , for example , that a set of @xmath10 are available in order to perform the desired quantum gates . a different assumption is that we start with only hamiltonians of the form @xmath51 between qubits @xmath52 and @xmath53 , but allows for one to adiabatically drag this hamiltonian to other `` gate teleporting '' hamiltonians . in this model we must ensure that the total system remains in the ground space for the entire evolution , so we must also adiabatically transition from our canonical initial hamiltonian @xmath54 to a new hamiltonian @xmath55 which leaves the @xmath52 qubit untouched but prepares @xmath56 on the @xmath53 qubit for agt . we call this adiabatic gate preparation ( agp ) . in general , such an evolution is nt directly possible for an arbitrary choice of @xmath57 . ( for example , consider @xmath58 . ) we can circumvent this by using a universal gate set for a single qubit where every member of the gate set yields an @xmath59 with a gap . for instance , we can choose the unitaries @xmath60 which have the requisite properties . the @xmath61 matrix is , up to a phase , a square root of the hadamard matrix , i.e. @xmath62 , while @xmath63 satisfies @xmath64 . the minimum agp gaps are @xmath65 and @xmath66 , respectively , at @xmath30 . together , @xmath61 and @xmath63 generate @xmath67 and hence are universal for single - qubit operations ( see pg . 196 of @xcite ) . next consider how to achieve two - qubit gates during the swapping of two qubits . to do this we follow as above , but instead of applying a single - qubit gate , we apply a two - qubit gate on the final two output qubits . for example , suppose that we wish to apply a controlled - phase between two logical qubits . then we start with @xmath68 and end with the hamiltonian @xmath69 where @xmath70 is the controlled - phase between the the third and sixth physical qubit . notice that the gap in this system is again the same constant @xmath65 , but now we require three - qubit interactions . we can bypass the inconvenient three - qubit interactions by using perturbation theory gadgets @xcite , i.e. two - body hamiltonians whose low energy dynamics mimic three - qubit interactions . the price is a reduction in the energy gap by a constant . in the appendix at the end of this paper we provide a detailed analysis of one such construction . the crux of this analysis shows that we can use two ancilla qubits and interactions of strength @xmath9 and @xmath71 to produce an adiabatic evolution with energy gap @xmath72 with a gate fidelity of @xmath73 . , @xmath74 , and @xmath75 we can perform universal quantum computation . here we diagram how this works for a single - qubit computation ( circuit below , the hamiltonians at different times diagramed from top to bottom . ) each circle represents a qubit , and a bar represents a two - qubit hamiltonian in our scheme , rotated by a labeled unitary @xmath76 . notice how in each step to the next hamiltonian , the qubit is swapped over two qubits ( the arrows ) and a gate is applied to this qubit . thus the gates to be applied are encoded spatially across the the three hamiltonians . the @xmath77th gate thus depends on the the hamiltonian @xmath78 with the gate being applied changing the interaction between qubits @xmath79 and @xmath80 in this hamiltonian . generalizing to more than one qubit this proves that universal holonomic quantum computation can be done by interpolation between only three hamiltonians . ] putting this all together we have shown how to use agt to perform one- and two - qubit gates by teleporting quantum information adiabatically between qubits . given the ability to prepare fiducial initial single - qubit states and the ability to measure the qubits which contain the state of the final system , we then obtain a model equivalent in power to the standard circuit model of qc . _ relationship to holonomic qc _ in holonomic quantum computing ( hqc ) one uses a cyclic adiabatic evolution of a hamiltonian around a loop in parameter space to produce a quantum gate . almost all hqc is cast within the context of cyclic evolutions , with the exception of kult _ et al . _ @xcite who pointed out that noncyclic geometric gates are also possible . agt is a example of a noncyclic geometric gate : so long as the evolution is adiabatic and we remain within the control manifold defined by the two interactions we are turning on and off , the desired gate is enacted independent of the actual time dependence of the path taken . our construction is distinguished in two ways . first , we achieve robustness by turning on and off interactions between two different subsystems ( as opposed to controlling interactions within the same system ) , and we expect that the separation of control needed to make geometric evolution robust will be much easier to achieve in this setting . second , our explicit connection to gate teleportation leads directly to universal qc and enables methods from fault - tolerance theory . _ possible architectures _ there are many different schemes for using the above agt primitives to build a universal quantum computer . using minimal resources , we can build a circuit on @xmath81 qubits using only @xmath82 qubits ( @xmath83 qubits for the two extra gates and @xmath84 for the ancillas in the perturbation gadgets ) assuming that we can move the qubits involved in the hamiltonians around at will . more realistic and interesting architectures disallow such movement , but allow the parallel circuit elements required for fault - tolerant qc . one very compelling architecture builds a circuit on @xmath81 qubits using @xmath85 qubits ( plus @xmath81 ancilla gadget qubits ) in a quasi - one - dimensional architecture . the idea here is simply that one can perform alternating steps in a quantum circuit by gate teleportation from the first @xmath81 qubits to the third @xmath81 qubits and then back to the first @xmath81 qubits . another possible architecture builds a quantum circuit of length @xmath86 on @xmath81 qubits onto teleportation across @xmath87 qubits by simply imprinting the quantum circuit being implemented spatially ( in a manner similar to what occurs in one - way quantum computing @xcite . ) thus we can perform universal qc by interpolating between just three different fixed hamiltonians ( see fig . [ fig ] . ) _ fault tolerance _ a full analysis of fault - tolerance in the piecewise adiabatic scheme is beyond the scope of this letter , but here we argue that our system should show similar behavior to fault - tolerance in the standard quantum circuit model . the reason for this is simply that agt , while using adiabatic evolution , essentially has the behavior of producing a gate on some ( teleported ) quantum information . thus we could use the standard techniques for proving a threshold on this model . that said , however , in practice this model may perform significantly better than the standard circuit model . the reason is that the system is always performing adiabatic evolution with a constant energy gap ( unlike many other models which yield energy gaps which scale inversely as a polynomial in the number of qubits . ) thus we obtain two of the benefits of adibatic qc , ( 1 ) the system is separated by a constant energy barrier from , and thus at low temperature is robust to , excitation out of the ground state ( a form of leakage error ) and ( 2 ) considerable robustness exists with respect to varying the tunings which change the hamiltonian adiabatically . _ comparison to other schemes _ using piecewise adiabatic quantum gate teleportations to build a quantum computer shares similarities with many other schemes , but differs in many respects as well . like universal adiabatic qc , the scheme uses a smooth one way interpolation between an initial and final hamiltonian , but we use multiple such interpolations . like holonomic qc , we rely on degenerate levels of a hamiltonian , but here our adiabatic evolution is not cyclic . along these lines , our scheme is related to a recent method to make holonomic qc fault - tolerant @xcite by using interpolations between encoded pauli operators . in contrast to our proposal , these are done in a cyclic fashion and with three - qubit interactions . further we achieve a gate by controlling interactions between separate subsystems , thus insuring that the geometric robustness depends only on the degree to which these independent controls can be manipulated . finally the scheme is similar in spirit to recent proposals to use spin chains with adiabatic time - dependent interactions to transmit quantum information @xcite , where interpolation between two spin-@xmath88 hamiltonians was used to transmit quantum information down the chain with an energy gap that scaled ( at least numerically ) as @xmath89 where @xmath86 is the length of the chain . by contrast , our scheme maintains a constant energy gap for the entire computation . while both schemes require similar transmission times , the former @xcite has a small energy gap , which will be a problem when using this scheme at finite temperature . furthermore , by explicitly connecting our scheme to gate teleportation , we achieved a universal qc . _ discussion _ we have shown how to build a universal quantum computer using a series of piecewise adiabatic quantum evolutions related to teleportation . this opens up a novel architecture for building a quantum computer based entirely on adiabatic quantum evolutions between two - qubit interactions and it considerably simplifies the control requirements for building a quantum computer . after completing this paper we became aware of concurrent work done independently by oreshkov @xcite showing a similar result using cyclic two - qubit interpolations . we thank d. gottesman for discussions . db was supported by nsf grants 0803478 and 0829937 and darpa quest grant fa-9550 - 09 - 1 - 0044 . stf was supported by the perimeter institute for theoretical physics . research at perimeter is supported by the government of canada through industry canada and by the province of ontario through the ministry of research & innovation . 17 r. raussendorf and h. j. briegel , phys . rev . lett . * 86 * , 5188 ( 2001 ) . d. aharonov _ et al . _ , in _ 45th annual ieee symposium on foundations of computer science _ ( 2004 ) , pp . 4251 . p. zanardi and m. rasetti , phys . lett . a * 264 * , 94 ( 1999 ) . a. m. childs , e. farhi , and j. preskill , phys . rev . a * 65 * , 012322 ( 2001 ) . c. h. bennett _ et al . _ , phys . rev . lett . * 70 * , 1895 ( 1993 ) . e. farhi _ et al . _ , _ quantum computation by adiabatic evolution _ ( 2000 ) , . d. gottesman and i. l. chuang , nature * 402 * , 390 ( 1999 ) . g. schaller , phys . rev . a * 78 * , 032328 ( 2008 ) . d. kult , j. berg , and e. sjqvist , phys . rev . a * 74 * , 022106 ( 2006 ) . s. jansen , m. b. ruskai , and r. seiler , j. math . phys . * 48 * , 102111 ( 2007 ) . g. schaller , s. mostame , and r. schutzhold , phys . rev . a * 73 * , 062307(2006 ) . m. a. nielsen and i. l. chuang , _ quantum computation and quantum information _ ( cambridge university press , cambridge , 2000 ) j. kempe , a. kitaev , and o. regev , siam j. comput . * 35 * , 1070 ( 2006 ) . r. oliveira and b. terhal , quant . inf . comp . * 8 * , 0900 ( 2008 ) . s. d. bartlett and t. rudolph , phys . rev . a * 74 * , 040302(r ) ( 2006 ) . o. oreshkov , t. a. brun , and d. a. lidar , phys . rev . lett . * 102 * , 070502 ( 2009 ) . k. eckert , o. romero - 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Dow Jones Reprints: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues, clients or customers, use the Order Reprints tool at the bottom of any article or visit www.djreprints.com Astronomers are tracking an asteroid about the size of an aircraft carrier that on Tuesday will pass by Earth, within the moon's orbit, in the closest approach of such an object in a generation. The 1,300-foot-wide asteroid, known as 2005 YU55, poses no hazard, experts at NASA's Jet Propulsion Laboratory said. They are monitoring the spinning space rock by radar as it nears and eventually speeds past Earth at a distance of 201,000 miles. The asteroid is going 29,000 miles per hour, according to astronomers at the University of Arizona. It is the first time since 1976 that an asteroid ... ||||| Scientists at NASA's Near-Earth Object Programme, which tracks asteroids and comets, ruled out any chance of impact. They are using the close encounter to learn more about the space rock known as 2005 YU55. The last time a cosmic interloper this size came this close to Earth was in 1976 and it will not happen again until 2028. Since late last week, antennas at the space agency's Deep Space Network in California have been monitoring the quarter-mile-wide asteroid as it approaches from the direction of the sun. The Arecibo Observatory in Puerto Rico planned a viewing Tuesday when the asteroid is set to make its closest pass at a distance of 202,000 miles at 11.28pm GMT. Since its discovery six years ago by a University of Arizona astronomer, scientists have learned a great deal about 2005 YU55. Its surface is coal black, and it spins slowly through space. Amateur skygazers who want a glimpse need two things: a good sky chart and a 6-inch telescope or larger since the asteroid is too faint to detect with the naked eye. Even with a telescope, sighting is not guaranteed. The glare from the moon may make the asteroid difficult to spot.

– At 6:28pm Eastern time tonight, an aircraft carrier-sized asteroid will swing by Earth at a distance of 201,000 miles, which is within the moon’s orbit. That’s the closest an asteroid has come to the planet since 1976, but don’t worry: NASA has determined the space rock poses no threat, the Wall Street Journal reports. You won’t be able to view it with the naked eye, but if you have a good sky chart and a 6-inch or larger telescope, you may have a shot, the Telegraph adds. The 1,300-foot-wide 2005 YU55 is traveling at 29,000 miles per hour. Researchers have been monitoring it, and will learn more about it through radar images. Asteroids are among the solar system’s oldest objects, and astronomers hope to glean clues about the origins of life on our planet. “This is an extraordinary opportunity to look at an extremely important type of asteroid,” says one NASA scientist. “A small army of astronomers are pretty excited about it.” Click for more on the asteroid.

the nature of the extragalactic gamma ray background emission has been a topic of great interest since egret collaboration evaluated its spectrum in the range from 30 mev to 100 gev @xcite . the diffuse emission coming from beyond the galaxy was determined by subtracting the contributions of resolved point sources , the diffuse galactic emission , and the instrumental background from the gamma - ray intensities observed by egret . the emission is found to be a power law in energy @xmath0 and is highly isotropic on the sky . @xcite suggested that blazars can explain up to 25 per cent of the extragalactic emission . the hypothesis that the flux is predominantly due to blazars seems to be reinforced by a new evaluation of the extragalactic emission @xcite which is slightly lower and steeper than that found by @xcite . the result is not consistent with a power law and shows some positive curvature which the authors relate to an origin in blazars emission . @xcite recently suggested that up to 85 per cent of the extragalactic emission could arise from blazars . according to @xcite blazars can account for the entire extragalactic @xmath1-ray background observed by egret . above 100 mev normal galaxies contribute from 3 to 10 per cent of the observed diffuse extragalactic flux . however from the analysis of @xcite the spectrum of normal galaxies seems to differ from the extragalactic diffuse emission spectrum . @xcite have suggested that the extragalactic diffuse arises from cosmic rays interacting with intergalactic gas . this contribution seems to disagree with the diffuse gamma ray spectrum according to @xcite . @xcite suggested fossil radiation from shock accelerated cosmic rays during structure formation as possible contribution . @xcite have estimated that inverse compton scattering of starlight photon fields by the ultrarelativistic electrons in kiloparsec - scale jets in fr i radio galaxies contributes about one percent to the egret extragalactic flux . @xcite and @xcite have shown that upscattering of cmb to @xmath1-ray energies by cosmic ray electrons and protons does not provide a sinificant contribution to the diffuse extragalactic emission . however , the question about the origin of the extragalactic emission is still open and can possibly be solved by admitting that different sources contribute to it . in fact all unresolved discrete sources outside the galaxy contribute to the extragalactic background emission ; the problem is clearly to understand how big the different contributions are . as already pointed out by @xcite , who considered grbs as a source for the diffuse gamma - ray emission at mev energies , prompt and delayed emissions from grbs should also contribute to the diffuse extragalactic emission , especially if some grbs emit photons in the gev - tev energy . in fact , outside the grb source , due to interactions with cosmic infra - red background photons , most of the high energy grb photons produce high - energy electron - positron pairs . the pairs inverse compton scatter off cmb photons and produce secondary photons , which in turn interact with ir photons and generate other pairs . multiple inverse compton scatterings occur until the energy of the secondary photons is no longer large enough to trigger pair production with the ir photons . when the energy of the scattered photons is not sufficient to produce a subsequent pair , the photons travel to the earth without undergoing further absorption . after multiple pair - production and inverse compton processes , the initial energy of the tev photons escaping the grbs will have been shifted to mev - gev energies @xcite . the data on extragalactic diffuse emission in the mev - gev energy range are thus useful to put constraints on high energy emission from gamma ray bursts at gev - tev energy . in the following we assume a flat cosmological model with normalized hubble constant @xmath2 , with @xmath3 and @xmath4 . cosmological distances and volumes are calculated following @xcite . gamma ray bursts are cosmological spots of short , intense and narrowly beamed @xmath1-ray emission , whose observed isotropic luminosities , @xmath5 , are in the range of @xmath6 erg / s . the huge energy released by grbs is almost certainly produced by ultra - relativistic flows , whose bulk lorentz factors @xmath7 may vary in the range of 100 and 1000 , with a typical value of 300 @xcite . the widely accepted fireball internal - external shock model for grbs envisages that high energy protons and electrons are accelerated in shocks by interaction with magnetic fields . the process of fermi acceleration leads to electron and proton power - law spectra of index between -2 and -3 . electrons and protons cool through synchrotron emission . since the electron cooling time is shorter than the proton cooling time , as a first approximation , the grb prompt spectrum is believed to be dominated by electron synchrotron emission only . the observed prompt spectrum arising from electron synchrotron emission is a band function @xcite , proportional to @xmath8 below the synchrotron peak energy , @xmath9 , with @xmath10 about -1 and to @xmath11 above the peak energy , with @xmath12 usually between -2 and -3 . below the synchrotron self absorption energy , @xmath13 , low energy photons are absorbed by fireball electrons in a magnetic field by synchrotron self - absorption . erg / s and located at @xmath14 . the slope @xmath15 and @xmath16 varies bewteen -2 and -3 for both synchrotron and ic spectra . the ratio @xmath17 between the synchrotron peak flux and the tev emission peak flux is assumed to be 10 . [ fig1],width=453 ] high energy ( up to tev ) emission has been detected in some grbs @xcite . according to the fireball model , tev photons can be produced in both internal @xcite and external @xcite shocks , either through electron inverse compton or proton synchrotron emission . @xcite proposed that the cross inverse compton scattering between the photons and electrons in forward and reverse shocks can also produce tev photons . tev photons can be also generated through inverse compton scattering of shock accelerated particles in external shocks off a bath of photon that overlaps the shocked region . the photon bath could be either the prompt gamma - ray emission itself @xcite or the late - time x - ray flares @xcite . for such distant sources as grbs , tev photons are mostly absorbed through pair production with cosmic background radiation ( cbr ) , but some indications of tev gamma rays from grbs at low redshift were provided by experiments like milagro @xcite , hegra @xcite and tibet @xcite . in our calculation tev prompt energy photons are taken into account in the prompt spectrum without investigating the details of the way they are created . we model the grb prompt tev emission as an additional broken power law with low energy spectral index @xmath15 and high energy spectral index @xmath18 . the synchrotron peak energy @xmath9 depends on the isotropic energy of the burst @xcite . in order to match the typical observed @xmath9 at 100 kev - 1 mev , the typical random electron lorentz factor @xmath19 is about 300 - 1000 . since most high energy emission components are related to inverse compton ( ic ) scattering , we design our high energy component to mimic the ic in the internal shocks . the typical separation between the synchrotron typical frequency and the ic typical frequency is @xmath20 , which varies between @xmath21 and @xmath22 . so the break energy of the additional tev component is chosen to be around @xmath21 times the synchrotron peak @xmath9 @xcite . the relative energies contained in the synchrotron component and the ic component depend on the ic @xmath23-parameter @xcite @xmath24 for @xmath25 , where @xmath26 and @xmath27 are shock energy equipartition parameters for electrons and magnetic fields , respectively . because of a possible klein - nishina limitation , this @xmath23 parameter could not be too high . an optimistic value would be around 10 , corrsponding to @xmath28 ( see fig . [ fig1 ] ) . this requires that the grb internal shocks are not very magnetized . grb emission is likely narrowly beamed . the jet may be top - hat shaped with uniform energy distribution inside the jet cone and a sharp drop off at the edge @xcite or `` structured '' with angle - dependent energy density inside the jet @xcite . the total amount of emission energy corrected for the beaming effect is likely standard , about @xmath29 erg @xcite . the average beaming factor ranges in the literature from around 75 @xcite to 500 @xcite . photon - photon absorption through pair production inside the grb source region controls the range in energy and the amount of radiation emitted . our following treatments closely follow @xcite . in fig . [ fig2 ] we plot the optical depths corresponding to the different processes taking place inside the grb source region , @xmath30 absorption , electron compton scattering and @xmath31 . the grb isotropic luminosity is @xmath32 and the observed time variability is @xmath33 s. the time variability is an important parameter for the description of gamma ray bursts . in fact the shock radius @xmath34 is proportional to the time variability @xmath35 and the peak volume number density of photons is defined as @xmath36 as shown in fig . [ fig2 ] , @xmath30 pair production within the grb attenuates the prompt spectrum , while electron compton scattering and @xmath31 have optical depths less than 1 for the typical parameter sets we are adopting . the optical depth for @xmath1-ray absorption through pair production is the integral above the synchrotron self absorption energy @xmath37 and below the klein nishima limit energy @xmath38 where the maximum electron lorentz factor is @xmath39 . @xcite @xmath40 in eq . [ eqn : tau ] the cross section for @xmath1-@xmath1 pair production @xmath41 is @xmath42 with @xmath43 @xmath44 in eq . ( [ eqn : tau ] ) is the number density of photons per energy in the comoving frame arising from synchrotron and higher energy processes . the total number density of photons is given as a superposition of different synchrotron and possibly higher energy power law spectra @xmath45 where @xmath46 \frac{d { { n_2}'}_{\gamma}}{d{e'}_{\gamma } } & = & \frac{{n'}_{\gamma } } { { { e'}_{pk } } } ( \frac{{{e'}_{\gamma}}}{{e'}_{pk}})^{\beta } \quad \quad \mbox{for $ { { e'}_\gamma}_{pk } < { e'}_{\gamma } < { e'}_{max}$ } \\[2 mm ] \frac{d { { n_3}'}_{\gamma}}{d{e'}_{\gamma } } & = & c \ , \frac{{n'}_{\gamma}}{{{e'}_{pk2}}}\ , ( \frac{{{e'}_{\gamma } } } { { e'}_{pk2}})^{\alpha } \quad \quad \mbox{for $ { e'}_{min } < { e'}_\gamma < { e'}_{pk2 } $ } \\[2 mm ] \frac{d { { n_4}'}_{\gamma}}{d{e'}_{\gamma } } & = & c \ , \frac{{n'}_{\gamma } } { { { e'}_{pk2 } } } ( \frac{{{e'}_{\gamma}}}{{e'}_{pk2}})^{\beta } \quad \quad \mbox{for $ { e'}_{\gamma } > { e'}_{pk2}$ } \,.\end{aligned}\ ] ] @xmath47 @xmath48 and @xmath49 are the synchrotron peak energy and the higher emission peak energy , respectively . @xmath50 is the synchrotron self absorption energy , @xmath51 is the synchrotron cut off corresponding to the maximum energy the electrons are accelerated to by the fermi mechanism and @xmath52 the ic klein - nishima limit . @xmath53 is the ic - boost of the synchrotron self - absorption frequency . the ratio @xmath54 of the high energy component energy flux , @xmath55 , and the synchrotron energy flux , @xmath56 at the peaks is given by @xmath57 which is adopted as the most optimistic value @xmath58 in our calculations ( see above for more discussion ) . here @xmath10 and @xmath12 are free parameters , which we assume to be @xmath15 and @xmath18 . -rays in the grb fireball . inverse compton and @xmath59 pair production do not attenuate the photon spectrum inside the grb source . the only process attenuating the photon spectrum is @xmath1-@xmath1 pair production . the attenuation is less efficient for higher bulk lorentz factors and for shorter variability times . the case of a grb having isotropic luminosity @xmath60 erg / s are time variability 0.01 second for different bulk lorentz factors is plotted . [ fig2],width=415 ] prompt photons are absorbed above the cutoff energy @xmath61 @xmath62 corresponding to the photon threshold energy for pair production with lower energy photons . the prompt photons are not absorbed above the so called thinning energy , the photon energy corresponding to optical depth @xmath63 @xmath64 where @xmath65/(m_e \ , \gamma_b)$ ] . for high enough bulk lorentz factors and for short enough time variabilities , grbs are optically thin at all energies . tev energy photons emitted by some processes within the grb will thus be able to leave the source and be observed by experiments like milagro . high energy gamma rays are attenuated also when travelling to us because they form pairs in collisions with low energy photons from the meta - galactic radiation field . following @xcite , the optical depth of gamma rays depends on the redshift @xmath66 and the gamma ray energy @xmath67 is parametrized by @xmath68 where @xmath69 gev . the attenuation rate versus energy is plotted for different redshifts in fig . the continous lines show the parametrization given in eq . [ kneiske ] , whereas the dashed lines represent the best fit model by @xcite . @xcite s recent calculations of intergalactic gamma - ray absorption making use of new spitzer and galex data diverge from those of @xcite at the higher redshifts due to the recent discovery that active star formation was taking place in young galaxies at redshifts out to beyond 6 . this gives larger optical depths at the higher redshifts than previously thought . -ray spectra through @xmath30 absorption at different redshifts . the continous lines show the parametrization of eq . [ kneiske ] and the dashed lines the best fit model of @xcite . [ fig3],width=415 ] throughout the rest of the paper we will assume that both the synchrotron and the higher energy grb spectrum have spectral indices @xmath15 and @xmath18 . also we will consider grb having time variability of 1 seconds and duration of 20 seconds and a bulk lorentz factor of 316 . inside and outside the grb , the spectrum is assumed to be only attenuated by @xmath30 reactions and the flux which leaves the source and is observed at a luminosity distance @xmath70 is @xmath71 where @xmath72 and @xmath73 and @xmath74 are the optical depths for pair production inside and outside the source . erg / s , bulk lorentz factor 316 and time variability 1 second . the slopes @xmath15 and @xmath18 for both synchrotron and ic spectra . the ratio between the synchrotron peak flux and the tev emission peak flux is assumed to be 10 . the solid lines represented the fluxes attenuated by @xmath30 absorption inside and outside the sources which are located at redshifts 0.1 , 0.3 and 1 . the dashed lines indicate the fluxes after attenuation inside the grb . [ fig4],width=453 ] outside the grb , due to @xmath30 interactions with cosmic infra - red background photons ( ir ) and the cosmic microwave background photons ( cmb ) , most of the high energy photons produce high - energy @xmath75 pairs . we assume that each lepton of the pair shares half of the energy of the initial grb photon , @xmath76 . the electron - positron flux from the synchrotron and the ic fluxes from one grb at a distance @xmath70 in the observer s frame is @xmath77 \label{eqn : pairs}\ ] ] the pair flux will be enriched as long as the burst lasts . the time integrated electron - positron fluxes are given by @xmath78 the pairs will inverse compton scatter off cmb and ir photons and produce secondary photons , which will in turn interact with ir photons and generate other pairs . multiple inverse compton scatterings will happen until the energy of the secondary photons is no longer sufficient to trigger a pair production with the ir photons . when the energy of the scattered photons is insufficient to produce a subsequent pair , the photons will travel to the detector without undergoing further absorption . when simulating the series of inverse compton scatterings we assume that all interactions happen very close to the source , at the redshift of the source itself . we also assume that the magnetic field is stronger than @xmath79 gauss in order for the flux to be isotropically radiated . the number of secondary photons per unit volume per photon energy interval created in the vicinity of a grb through one inverse compton scattering of the pairs in eq.([eqn : pairs ] ) off cosmic of the background radiation photons is @xcite @xmath80 & = & \int d { e_e } \int d { \epsilon}_{cmb } \frac{d { \sigma_{ic } } } { d e_{\gamma } } ( e_\gamma , { e_e } \,\epsilon_{cmb } ) \ , u_{cmb } ( { \epsilon}_{cmb},z ) \ , ( { \frac{d n_e}{da \ , d{e_e}}})_{grb}\end{aligned}\ ] ] @xmath81 where @xmath82 can be either the differential thomson cross section ( for low energy pairs ) or the differential klein - nishina formula ( for high energy pairs ) @xcite , @xmath83 is the density of cbr photons per unit volume per photon energy interval at redshift @xmath66 @xcite . if inverse compton scattered photons have a high enough energy , they will be absorbed by the ir photons . in order to evaluate the contribution from scattered @xmath1-ray emission from all grbs we input the observed grb redshift distribution @xcite @xmath84 in eq.([dist_guetta ] ) , @xmath85 is the luminosity function , defined as the comoving space density of grbs in the interval @xmath86 and @xmath87 . following @xcite , we derive the luminosity function @xmath85 by assuming a broken power law with lower and upper limit , @xmath88 and @xmath89 , respectively , where @xmath90 erg / s , @xmath91 the normalization constant @xmath92 @xmath93 is obtained by imposing the integral of @xmath85 to give unity . we assume @xmath94 , @xmath95 , @xmath96 and @xmath97 . the integration over @xmath5 is performed over the interval indicated in @xcite . in eq.([dist_guetta ] ) the redshift distribution of grbs @xmath98 is @xmath99 where @xmath100 and @xmath101 is the observed rate of grb per differential co - moving volume . @xmath102 where @xmath103 is the angular diameter distance and @xmath104 is the hubble distance . the secondary source function in eq.([inverse_integral1 ] ) , iterated over multiple scatterings , is integrated over the comoving line of sight distance @xmath105 @xmath106 and weighted over the number of grbs @xmath107 per unit time to obtain the total counting rate of the diffuse background flux @xmath108 where the integration over the redshift is performed from redshift 0.01 , corresponding to about 40 mpc , to redshift 10 . as we mentioned earlier if we assume that the intergalactic magnetic field is stronger than @xmath79 gauss the beamed emission from grbs is isotropically radiated . so the flux contribution for each burst is lower by the beaming solid angle divided by @xmath109 . however there are more grbs , increased by @xmath110 divided by the beaming solid angle , which contribute to the diffuse background . so the two beaming factor corrections cancel out and the unknown beaming fraction does not influence eq.([delayed_partial ] ) . the total flux from the prompt grb emission is given by the following integral @xmath111 where @xmath112 is the differential gamma ray prompt flux from each grb in eq.([eqn : fluxemitted ] ) , measured in @xmath113 , @xmath114 is the redshift dependent number of grbs per unit time given in eq.([dist_guetta ] ) . in fig . [ fig5 ] we plot the sum of the prompt and scattered grb emissions assuming an average value of the bulk lorentz factor equal to 316 . the average time variability of the bursts is assumed to be 1 second and the duration 20 seconds . the input energy flux at the high energy peak @xmath115 is assumed 10 times stronger than that at the synchrotron peak @xmath9 , i.e. @xmath116 ( see fig . [ fig1 ] ) . for higher average bulk lorentz factors @xmath7 , the pair production inside the grb source region is less efficient and therefore the @xmath1-ray flux escaping the grbs will be higher and both the prompt and the scattered fluxes in fig . [ fig5 ] will be higher . if the average time variability @xmath35 , which is related to the dimensions of the grb shock radius , is lower , then the number of photons emitted through electron synchrotron emission inside the grb source region is higher and consequently we expect higher prompt and scattered fluxes . the second peak energy @xmath115 is the energy at which we expect the maximum tev energy flux and , as pointed out , is constrained by the observed synchrotron spectrum to be between @xmath117 and @xmath118 times the synchrotron peak energy @xmath9 . if we consider a lower value of @xmath115 , we have more photons at lower energies which scatter off the cbm and ir photons and therefore the cascade processes started by the grb photons off the interstellar radiation fields will be interrupted sooner and will produce lower scattered photon fluxes . a lower second peak energy @xmath115 might also imply a more efficient pair production absorption inside the grb source region , as shown in fig . [ fig2 ] . finally assuming a shorter average time duration @xmath119 for the grbs less photons will be injected by the grbs and the scattered flux will be lower . as a back of the envelope calculation , by assuming that the average amount of energy released by each grb is of the order of @xmath120 , the grb rate is one per day and the average redshift is 1 , the total flux emitted by all grbs is roughly of the order of @xmath121 . this is roughly consistent with our more rigorous calculations . current limits for the contribution of blazars and other sources to the extragalactic diffuse emission indicate that between 25 and 50 per cent of the extragalactic diffuse emission is not explained yet and , in principle , can be due to any other unresolved source outside the galaxy @xcite . the prompt and scattered emissions from grbs should contribute to the diffuse extragalactic emission , too . in fact , outside the grb source , due to interactions with cosmic infra - red background photons , most of the high energy grb photons produce produce high - energy electron - positron pairs . the pairs inverse compton scatter off cmb photons and produce electromagnetic cascades . in this way the beamed gev - tev grb emission is re - processed and converted into an isotropic mev energy emission , which contributes to the extragalactic diffuse emission . we have modeled the emission from grbs as due a low energy synchrotron spectrum and a higher energy ic spectrum . the ic spectrum extends up to klein - nishima limit . also we have assumed the higher energy ic emission from grbs to be 10 times stronger than the lower energy standard synchrotron emission . this assumption is equivalent to requiring that the grb inverse compton y - paramater is equal to 10 . using the batse peak flux distribution @xcite derived the grb luminosity function assumed for our estimates . the luminosity function can be approximated by a broken power law with a break peak luminosity of @xmath122 , a typical jet angle of 0.12 rad , and a local grb rate of @xmath123 . using the redshift and luminosity distributions derived by @xcite we have summed up the prompt and scattered emissions from all grbs in the universe . the sum of the prompt and scattered emission from all grbs is shown in fig . [ fig5 ] for a particular choice of grb parameters . from our optimistic model the @xmath1-ray emission from prompt and scattered grb emissions can provide only a small fraction of the extragalactic diffuse emission at egret energies and can not therefore explain the missing flux . from fig . [ fig5 ] the sum of prompt and scattered emission from synchrotron and 10 times stronger ic emissions from all grbs is less than the part of the extragalactic diffuse emission not explained by blazars , admitting that the blazars explain between 25 and 50 percent of the isotropic extragalactic emission . our optimistic grb model does not overproduce the extragalactic @xmath1-ray background . we can thus conclude that tev energy prompt fluxes from grbs can be at least 10 times bigger than the synchrotron flux without violating the limit imposed by the extragalactic diffuse emission . in allowing tev energy fluxes from grbs of comparable or even stronger intensity to the mev fluxes , our result is consistent with those models @xcite which predict fluences at tev energies similar to those at mev energies , the observations of high energy emission from grb 970417a with milagrito @xcite and the analysis of grb 941017 done by @xcite , which pointed out the existence of a second flux from grb 941017 that can not be explained as synchrotron emission . experiments like milagro and future missions like glast or mini - hawc should therefore devote part of their efforts to investigate vhe emissions from grbs . we note that the recent swift detection of grb 060218 @xcite suggests that there might be a low - luminosity population of grbs with a much higher event rate @xcite . on the other hand , these bursts have low luminosities and tend to be x - ray flashes @xcite , which would compensate their high event rate . future analyses are needed to reveal the contribution from this category of grbs . and @xmath18 for both synchrotron and ic spectra . the ratio between the synchrotron peak flux and the tev emission peak flux is assumed to be 10 . the flux is attenuated by @xmath30 absorption inside and outside the sources . [ fig5],width=453 ]

tev gamma rays emitted by grbs are converted into electron - positron pairs via interactions with the extragalactic infrared radiation fields . in turn the pairs produced , whose trajectories are randomized by magnetic fields , will inverse compton scatter off the cosmic microwave background photons . the beamed tev gamma ray flux from grbs is thus transformed into a gev isotropic gamma ray flux , which contributes to the total extragalactic gamma - ray background emission . assuming a model for the extragalactic radiation fields , for the grb redshift distribution and for the grb luminosity function , we evaluate the contribution of the grb prompt and scattered emissions to the measured extragalactic gamma - ray flux . to estimate this contribution we optimistically require that the energy flux at tev energies is about 10 times stronger than the energy flux at mev energies . the resulting gamma - ray diffuse background is only a small fraction of what is observed , allowing blazars and other sources to give the dominant contribution .

the reported experiments have been performed in the research centre jlich at the cooler synchrotron cosy @xcite by means of the cosy11 detector system @xcite presented in fig . the collision of a proton from the cosy beam with a proton or deuteron cluster target may cause an @xmath0 meson creation . in that case all outgoing nucleons have been registered by the cosy11 detectors , whereas for the @xmath4 meson identification the missing mass technique was applied . reaction is presented . , scaledwidth=55.0% ] the main goal of this experiment was the determination of the excitation function for the quasi - free @xmath6 reaction near the kinematical threshold . the motivation was the comparison of the @xmath7 and @xmath6 total cross - sections in order to learn about the production mechanism of the @xmath4 meson in the channels of isospin 1 and 0 , and to investigate aspects of the gluonium component of the @xmath4 meson . the ratio @xmath8 has not been measured so far , and the existing predictions differ drastically depending on the model . cao and lee @xcite assumed , by analogy to the production of the @xmath3 meson , that the production of the @xmath4 meson proceeds dominantly via the s@xmath9(1535 ) resonance . as a consequence , they predicted within an effective lagrangian approach a @xmath10 value equal to the experimentally established @xmath11 value . in contrast , kaptari and kmpfer @xcite predicted a value of @xmath10 close to @xmath121.5 in the kinematic range of the cosy11 experiment with the dominant contribution coming from the meson conversion currents . in the extreme scenario of glue - induced production saturating the @xmath4 production cross - section , the ratio @xmath10 would approach unity after correcting for the final state interaction between the two outgoing nucleons . detailed description of measurement and data analysis is presented in @xcite . the result is shown in fig . [ cross_pn ] . the horizontal bars represents the intervals of the excess energy , for which the upper limit of the total cross - section was calculated . reaction as a function of the excess energy ( open squares ) . upper limit for the total cross - section for the @xmath6 reaction as a function of the excess energy ( dots ) . , scaledwidth=55.0% ] the total cross - section for the @xmath7 reaction was measured in previous experiments @xcite . it reveals a strong excess energy dependence , especially very close to threshold . this dependence must be taken into account when comparing to the results for the @xmath6 reaction which were established for 8 mev excess energy intervals . therefore , for a given interval of excess energy , we have determined the mean value of the total cross - section for @xmath7 reaction using the parametrisation of fldt and wilkin @xcite fitted to the experimental data @xcite . for the @xmath4 meson the upper limit of the ratio for the excess energy range @xmath13 $ ] mev is nearly equal to values of the ratio obtained for the @xmath3 meson , whereas for larger excess energy ranges @xmath14 $ ] mev and @xmath15 $ ] mev the upper limits of the ratio are lower by about one standard deviation each . the value of @xmath16 is @xmath17 6.5 at excess energies larger than @xmath18 mev @xcite suggests the dominance of isovector meson exchange in the production mechanism . the decrease of @xmath16 close to the threshold @xcite may be explained by the different energy dependence of the proton proton and proton neutron final state interactions @xcite . a smaller @xmath10 than @xmath19 is consistent with a possible greater role for singlet currents in @xmath4 production than @xmath3 production . if there are important new dynamics in the @xmath4 production process relative to eta production , a key issue is the relative phase @xcite of possible additional exchanges compared to the isovector currents which dominate the @xmath3 production . the observed limit thus constrains modelling of the production processes . to confirm these interesting observations and to go further , new experimental investigations with improved statistics are required . in principle , studies of @xmath20 reactions permit information about the proton meson interaction to be gained not only from the shape of the excitation function but also from differential distributions of proton proton and proton meson invariant masses . therefore , in order to investigate the proton@xmath3 interaction the cosy11 collaboration performed a measurement @xcite of the proton@xmath3 and proton proton invariant mass distributions close to the threshold at q = 15.5 mev , where the outgoing particles possess small relative velocities . indeed a large enhancement in the region of small proton@xmath3 and large proton proton relative momenta was observed . however , the observed effect can not be univocally assigned to the influence of the proton@xmath3 interaction in the final state @xcite , since it can also be explained by the admixture of higher partial waves in the proton proton system @xcite , or by the energy dependence of the production amplitude @xcite . the endeavor to explain the origin of the observed enhancement motivated the measurement of the proton proton and proton@xmath4 invariant mass distributions for the @xmath7 reaction presented in this article . detailed description of measurement and data analysis resulted in invariant mass distributions for the @xmath7 reaction is presented in @xcite . the absolute values of the cross - section for the @xmath7 reaction determined as a function of @xmath21 and @xmath22 are shown in fig . [ fig : norm_pp_peta ] . ) and proton@xmath4 ( @xmath22 ) invariant masses , for the @xmath7 reaction at the excess energy of q = 16.4 mev . the experimental data ( closed squares ) are compared to the expectation under the assumption of a homogeneously populated phase space ( thick solid lines ) and the integrals of the phase space weighted by the proton proton scattering amplitude - fsi@xmath23 ( dotted histograms ) . the solid and dashed lines correspond to calculations when taking into account contributions from higher partial waves and allowing for a linear energy dependence of the @xmath24 partial wave amplitude , respectively . , title="fig : " ] ) and proton@xmath4 ( @xmath22 ) invariant masses , for the @xmath7 reaction at the excess energy of q = 16.4 mev . the experimental data ( closed squares ) are compared to the expectation under the assumption of a homogeneously populated phase space ( thick solid lines ) and the integrals of the phase space weighted by the proton proton scattering amplitude - fsi@xmath23 ( dotted histograms ) . the solid and dashed lines correspond to calculations when taking into account contributions from higher partial waves and allowing for a linear energy dependence of the @xmath24 partial wave amplitude , respectively . , title="fig : " ] within the statistical and systematic error bars both model of deloff @xcite and of nakayama et al.@xcite describe the data well although they differ slightly in the predicted shapes . this indicates that perhaps , not only higher partial waves but also the energy dependence of the production amplitude should be taken into account . also , the inclusion of the proton proton final state interaction is not sufficient to explain the enhancement seen in the range of large @xmath21 values . within the achieved uncertainties , the shape of the proton proton and proton meson invariant mass distributions determined for the @xmath4 meson is essentially the same to that established previously for the @xmath3 meson . since the enhancement is similar in both cases , and the strength of proton@xmath3 and proton@xmath4 interaction is different @xcite , one can conclude that the observed enhancement is not caused by a proton meson interaction . therefore , on the basis of the presented invariant mass distributions , it is not possible to disentangle univocally which of the discussed models is more appropriate . as pointed out in @xcite , future measurements of the spin correlation coefficients should help disentangle these two model results in a model independent way . in the latest review by the particle data group ( pdg ) @xcite , two values for the total width of the @xmath0 meson are given . one of these values , ( 0.30 @xmath26 0.09 ) mev / c@xmath27 , results from the average of two measurements @xcite , though only in one of these experiments was @xmath25 extracted directly based on the mass distribution @xcite . the second value ( 0.205 @xmath26 0.015 ) mev / c@xmath27 , recommended by the pdg , is determined by fit to altogether 51 measurements of partial widths , branching ratios , and combinations of particle widths obtained from integrated cross - sections @xcite . the result of the fit is strongly correlated with the value of the partial width @xmath28 , which causes serious difficulties when the total and the partial width have to be used at the same time , like _ e.g. _ in studies of the gluonium content of the @xmath0meson @xcite . the value of the total width of the @xmath0 meson was established directly from its mass distribution independently of other properties of this meson , like _ e.g. _ partial widths or production cross - sections . the @xmath0 meson was produced in proton proton collisions via the @xmath1 reaction and its mass was reconstructed based on the momentum vectors of protons taking part in the reaction . the reader interested in the description of the detectors and analysis procedures can find detailed informations in ref . the momentum of the cosy beam and the dedicated zero degree cosy11 facility enabled the measurement at an excess energy of only a fraction of an mev above the kinematic threshold for the @xmath4 meson production . this was the most decisive factor in minimizing uncertainties of the missing mass determination , since at threshold the partial derivative of the missing mass with respect to the outgoing proton momentum tends to zero . in addition , close to threshold the signal - to - background ratio increases due to the more rapid reduction of the phase space for multimeson production than for the @xmath4 . the systematic error was estimated by studying the sensitivity of the result to the variation of parameters describing the experimental conditions in the analysis and in the simulation @xcite . finally , the total systematic error was estimated as the quadratic sum of independent contributions and is @xmath29 mev / c@xmath27 . the final missing mass spectra are presented in fig . the total width of the @xmath0 meson was extracted from the missing - mass spectra and amounts to @xmath30 @xmath31 mev / c@xmath27 . the result does not depend on knowing any of the branching ratios or partial decay widths . the extracted @xmath25 value is in agreement with both previous direct determinations of this value @xcite , and the achieved accuracy is similar to that obtained by the pdg @xcite . the work was partially supported by the european commission under the 7@xmath32 framework programme through the _ research infrastructures _ action of the _ capacities _ programme . call : fp7-infrastructures-2008 - 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we present results on the isospin dependence of the @xmath0 production cross - section in nucleon nucleon collisions , as well as the results of comparative analysis of the invariant mass distributions for the @xmath1 and @xmath2 reactions in the context of the proton@xmath3 and proton@xmath0 interaction . additionally , the value of the total width of the @xmath0 is reported as derived directly from the measurement of the mass distribution and an explanation of the experimental technique used in order to achieve a precision about an order of magnitude better then former experiments is included .

one of the most salient open problems in classical general relativity ( gr ) is proving the stability of the outer region of the stationary electro - vacuum black holes in the kerr - newman family . a complete proof of stability in the context of the non linear gr equations has only been given for minkowski spacetime @xcite ; the stability problem of more complex solutions of einstein s equation is usually approached by analyzing the behavior of linear test fields satisfying appropriate boundary conditions in order to establish if unbounded solutions are allowed . scalar test fields provide a first clue , whereas gravitational waves , that is , metric perturbations @xmath7 propagating on the background spacetime @xmath8 , give a more realistic approach to the problem . for vacuum spacetimes , assuming a cosmological constant @xmath0 , the metric perturbation @xmath7 satisfies the linearized einstein equation ( lee ) @xmath9 : = - \tfrac{1}{2 } \nabla^{{\gamma } } \nabla_{{\gamma } } h_{{\alpha}{\beta } } - \tfrac{1}{2 } \nabla_{{\alpha } } \nabla_{{\beta } } ( g^{{\gamma}{\delta } } h_{{\gamma}{\delta } } ) + \nabla^{{\gamma } } \nabla_{({\alpha } } h_{{\beta } ) { \gamma } } - \lambda \ ; h_{{\alpha}{\beta } } = 0,\ ] ] obtained by assuming that on a fixed four dimensional manifold @xmath10 ( the spacetime ) there is a mono - parametric family of solutions @xmath11 of the vacuum einstein field equation @xmath12 - \lambda g_{{\alpha}{\beta}}({\epsilon})=0\ ] ] around the unperturbed background " @xmath13 , and taylor expanding ( [ mpfs ] ) at @xmath14 . for tensor fields that depend functionally on the metric we use a dot to denote the `` perturbed field '' , which is the field obtained by taking the first derivative with respect to @xmath15 at @xmath14 , e.g. , for the riemann tensor , @xmath16.\ ] ] we make an exception for the metric field itself by adopting the standard notation @xmath17 and , as usually done in linear perturbation theory , defining @xmath18 , and @xmath19 . note that this convention implies that @xmath20 equation ( [ lee ] ) is the first order taylor coefficient of ( [ mpfs ] ) around @xmath14 , that is @xmath21 = \dot r_{{\alpha}{\beta } } - \lambda h_{{\alpha}{\beta}}$ ] . trivial solutions of this equation are @xmath22 where @xmath23 is an arbitrary vector field ; these amount to the first order in @xmath15 change of the metric under the pullback by the flow @xmath24 generated by the vector field @xmath23 . any two solutions @xmath7 and @xmath25 such that @xmath26 are related by this diffeomorphism and thus physically equivalent , this being the _ gauge freedom _ of linearized gravity . if a tensor field @xmath27 is a functional of the metric @xmath28 , then @xmath29 is a linear functional of @xmath7 and , under the _ gauge transformation _ ( [ gt2 ] ) we find that @xmath30 = \dot t[h ] + \pounds_{\xi } t.\ ] ] in particular , if @xmath27 is a scalar field , @xmath29 is gauge invariant iff @xmath31 for every vector field , that is , if @xmath27 is constant in the background . + curvature related scalar fields ( cs for short , not to be confused with the tetrad components of the weyl tensor in the newman - penrose formalism ) , are scalar fields obtained by a full contraction of a polynomial in the riemann tensor and its covariant derivatives , the metric and the volume form . although these fields partially characterize the metric , it is well known that the information they carry is limited , an extreme example of this fact being the _ vanishing scalar invariants spacetimes _ , which have a nonzero riemann tensor and yet _ every _ cs vanishes @xcite . this fact may suggest that the perturbation of cs under a given solution @xmath7 of the lee provide very limited information on @xmath7 . it was shown in @xcite , however , that for a schwarzschild black hole background , there are two gauge invariant combinations @xmath1 of perturbed css that fully characterize the gauge equivalence class @xmath32 $ ] of the corresponding solution of the lee . more precisely , let @xmath33 be the weyl tensor , @xmath34 the volume form , and consider the css @xmath35 the background values of these fields , that is , their value for the @xmath6 schwarzschild solution , are @xmath36 , @xmath37 and @xmath38 , where @xmath39 is the mass and @xmath40 the areal radius , then the fields @xmath41 made out of the first order variations of these cs , are gauge invariant . it was shown in @xcite that the linear map @xmath42 \to \left ( g_{-}\left([h_{{\alpha}{\beta } } ] \right ) , g_{+}\left([h_{{\alpha}{\beta } } ] \right ) \right)\ ] ] with domain the equivalence classes of smooth solutions of the lee preserving the asymptotic flatness , is injective . this implies that the scalars @xmath1 , beyond measuring the `` amount of distortion '' caused by the perturbation , encode _ all _ the relevant information on the perturbation class @xmath32 $ ] . a way to construct a class representative @xmath7 from the fields @xmath43 \right)$ ] is indicated in @xcite . + the stability concept introduced in @xcite is based on i ) the existence of the css @xmath1 for which ( [ i m ] ) is injective on smooth solutions of the lee that preserve the asymptotic flatness , and ii ) the proof that for this class of solutions of the lee the scalar fields @xmath43 \right)$ ] are bounded . more precisely , it is proved in @xcite that in the outer region @xmath44 @xmath45 are constants that can be obtained from the perturbation field datum at a cauchy slice . given that the scalars @xmath1 contain _ all _ the gauge invariant information on the perturbation , the fact that they remain bounded as the perturbation evolves through spacetime gives a meaningful notion of linear stability . + this concept of stability , that we call _ nonmodal _ , should be compared with prior linear gravity stability notions for the schwarzschild black hole . to this end we review the results in a short list of papers that were crucial in the development of this subject . it is important to stress that they all use the spherical symmetry of the schwarzschild spacetime to decompose a metric perturbation @xmath46 into even ( @xmath47 ) and odd ( @xmath48 ) @xmath49 _ modes_. here @xmath50 refers to the eigenspace of the laplace - beltrami operator acting on real scalar fields on @xmath51 corresponding to the eigenvalue @xmath52 , @xmath53 is an index labeling a particular basis of this @xmath54 dimensional space , and the parity @xmath55 accounts for the way @xmath56 transforms when pull - backed by the antipodal map on @xmath51 ( for details refer to section [ cstf ] ) . + the first work on the linear stability of the schwarzschild black hole is t. regge and j. wheeler 1957 paper @xcite , where the decomposition ( [ dec ] ) was proposed and the @xmath57 modes where recognized to be non - dynamical . at the time the very notion of black hole was unclear ( the term `` black hole '' was coined by j. wheeler some ten years later ) , and kerr s solution had not yet been discovered . this is probably why , although the @xmath58 even piece of the perturbation was readily identified as a mass shift in @xcite , the odd @xmath59 modes , which corresponds to perturbing along a kerr family @xmath11 with @xmath60 , was misunderstood ( see the paragraph between equations ( 37 ) and ( 38 ) in @xcite ) and the opportunity of producing a `` slowly rotating '' black hole at a time when there was no clue about a rotating black hole solution was missed . the decomposition ( [ dec ] ) in @xcite was done in schwarzschild coordinates @xmath61 in what came to be called the regge - wheeler ( rw , for short ) gauge . the lee in the even and odd sectors were shown to decouple , and the dynamical odd sector of the lee reduced to an infinite set of two dimensional wave equations , individually know as the rw equation : @xmath62 where ( adding a cosmological constant @xmath0 for future reference ) @xmath63 , @xmath64 , and @xmath65 the @xmath66 even sector lee , a much more intricate system of equations , was disentangled by f. zerilli in his 1970 paper @xcite and shown to be equivalent to the wave equations @xmath67 with potentials @xmath68 r^3 + 6 \mu^2 m r^2 + 36 \mu m^2 r + 72m^3}{r^3 \ ; ( 6m+ \mu r)^2 } , \;\ ; \mu=(\ell-1)(\ell+2).\ ] ] for @xmath69 the rw and zerilli potentials first appeared in @xcite . the solution of the lee in the rw gauge is then given in the form @xmath70\ ] ] where @xmath71 is a bilinear differential operator acting on @xmath72 and the spherical harmonics @xmath73 . note that , since focus is on non - stationary modes , only @xmath66 enter this formulation . the non - stationary solution space of the lee is thus parametrized by the infinite set of scalar fields @xmath72 that enter the series ( [ dec ] ) through ( [ rws ] ) . + every notion of gravitational linear stability of the schwarzschild black hole prior to @xcite was concerned with the behavior of the potentials @xmath72 of isolated @xmath49 modes ( we call this `` modal linear stability '' ) . in particular : * in @xcite it was shown that separable solutions @xmath74 that do not diverge as @xmath75 require @xmath76 , ruling out exponentially growing solutions in the odd sector . * in @xcite it was shown that separable solutions @xmath77 that do not diverge as @xmath75 require @xmath76 , ruling out exponentially growing solutions in the even sector . * in @xcite it was shown that , for large @xmath78 and fixed @xmath40 , @xmath79 decays as @xmath80 ( an effect known as `` price tails '' ) . * in @xcite , the conserved energy @xmath81 f dr\ ] ] was used to rule out uniform exponential growth in time . * also in @xcite , a point wise bound on the rw and zerilli potentials was found in the form @xmath82 are given in terms of the initial data @xmath83 to understand the limitations of these results it is important to keep in mind that the @xmath84 are an infinite set of potentials defined on the @xmath85 orbit space @xmath86 , whose first and second order derivatives @xmath84 enter the terms in the series ( [ dec ] ) through ( [ rws ] ) , together with first and second derivatives of the spherical harmonics . two extra derivatives are required to calculate the perturbed riemann tensor , as a first step to measure the effects of the perturbation on the curvature . thus , the relation of the potentials @xmath72 to geometrically meaningful quantities is remote , and the usefulness of the bounds ( [ modal - b ] ) to measure the strength of the perturbation is far from obvious . + the motivation of the nonmodal approach can be better understood if we put in perspective the progress made in @xcite , equation ( [ modal - b ] ) . the fact that the two dimensional wave equations ( [ rwe ] ) and ( [ ze ] ) can be solved by separating variables ( @xmath87 ) had previous works on linear stability focus on showing that @xmath88 must be real , a limited notion of stability that does not even rule out , e.g. , linear @xmath78 growth @xcite . to obtain the type of bounds ( [ modal - b ] ) one must `` undo '' the separation of variables and reconsider the original equations ( [ rwe ] ) and ( [ ze ] ) , as this allows to work out results that are valid for generic , non separable solutions . the idea behind the non modal stability concept introduced in this paper , is to go one step further and `` undo '' the separation of the @xmath89 variables that antecedes the reduction of the lee to ( [ rwe ] ) and ( [ ze ] ) , in order to get bounds for truly four dimensional quantities . when trying to make this idea more precise , one is immediately faced to the problem of _ which _ four dimensional quantity one should look at . if this quantity is to measure the strength of the perturbation , it should be a field related to the curvature change , and it should also be a _ scalar _ field , since there is no natural norm for a tensor field in a lorentzian background . if this scalar field does not obey a four dimensional wave equation ( or some partial differential equation ) , we do not have a clear tool to place bounds on it . thus , we are naturally led to the question of the existence of scalar fields made from perturbed css that , as a consequence of the lee , obey some wave - like equation . this is the problem we address in this paper . the name _ nonmodal stability _ is borrowed from fluid mechanics , where the limitations of the normal mode analysis were realized some thirty years ago in experiments involving wall bounded shear flows @xcite . in that problem , the linearized navier - stokes operator is non normal , so their eigenfunctions are non orthogonal and , as a consequence , even if they individually decay as @xmath90 , a condition that assures large @xmath78 stability , there may be important transient growths @xcite . take , e.g. , the following simple example ( from @xcite , section 2.3 and figure 2 ) of a system of two degrees of freedoms : @xmath91 obeying the equation @xmath92 , with @xmath93 \neq 0 $ ] a matrix with ( non orthogonal ! ) eigenvectors @xmath94 , say , @xmath95 consider the case @xmath96 . note that , although @xmath97 , that is , normal modes decay exponentially , if @xmath98 , then @xmath99 reaches a maximum norm @xmath100 at a finite time before decaying to zero . + for the odd sector of the lee , a four dimensional approach relating the metric perturbation with a scalar potential @xmath101 defined on @xmath102 ( instead of @xmath86 ) was found in @xcite , where it was noticed that the sum over @xmath49 of ( [ rws ] ) simplifies to @xmath103 = \frac{r^2}{3 m } { } ^ * c_{{\alpha}}{}^{{\gamma}{\delta}}{}_{{\beta } } \nabla_{{\gamma } } \nabla_{{\delta } } \left ( r^3 \phi \right),\ ] ] where @xmath101 is a field assembled using spherical harmonics and the rw potentials : @xmath104 the odd sector lee equations ( [ rwe ] ) for @xmath105 combined to the spherical harmonic equations for the spherical harmonics @xmath106 , turn out to be equivalent to what we call the four dimensional regge - wheeler equation which , adding a cosmological constant , reads @xmath107 note however that @xmath101 is no more than the collection of @xmath108 s , so its connection to geometrically relevant fields is loose . much more important is the fact , also proved in @xcite for @xmath6 , that the lee implies that the field @xmath109 _ also _ satisfies the [ 4drwe ] , as this is what allows us to place a point wise bound on @xmath110 . + the even sector of the lee is more difficult to approach . is the simplicity of the rw potential ( [ rwp ] ) , with the obvious @xmath111 term , what suggested considering the field ( [ 4drf ] ) . the way @xmath50 appears in ( [ zp ] ) , instead , is a clear indication that there is no natural 4d interpretation of ( [ ze ] ) . is a map exchanging solutions of the [ rwe ] and [ ze ] equations , found by chandrasekhar @xcite , what ultimately allows us to also reduce the even non stationary lee equations to ( [ 4drwe ] ) . as a consequence , the entire set of non stationary lee reduces to two fields satisfying equation ( [ 4drwe ] ) , as stated in theorem [ bij ] below . + the purpose of this paper is twofold : ( i ) to extend the results in @xcite to schwarzschild black holes in cosmological backgrounds , and ( ii ) to explain in detail a number of technicalities omitted in @xcite due to the space limitations imposed by the letter format . for @xmath112 we give a proof of non - modal stability . we leave aside the treatment of stability of the schwarzschild anti de sitter ( sads ) black hole , since the issue of non global hiperbolicity and ambiguous dynamics due to the conformal timelike boundary takes us away from the core of the subjects addressed here . we show however that there is ( at least ) one choice of robin boundary condition at the time - like boundary for which there is an instability , and we explicitly exhibit this instability and its effect on the background geometry . to the best of our knowledge , this has not been informed before . a systematic study of the gravitational linear stability of sads black holes under different boundary conditions is to be found in @xcite . + we have found that @xmath113 defined in ( [ gpm ] ) are appropriate variables to study the most general gravitational linear perturbations of schwarzschild ( a)ds black holes . the @xmath57 pieces of these fields encode the relevant information on the stationary modes , which are perturbations within the kerr family ( parametrized by mass @xmath39 and the angular momenta components ) , whereas the @xmath66 terms encode the dynamics . more precisely : * @xmath5 contains no @xmath58 term , time independent @xmath59 terms proportional to the first order angular momenta components @xmath114 , and a time dependent @xmath115 piece obeying the 4drw equation . * @xmath4 contains no @xmath59 term , a time independent @xmath58 piece proportional to a mass shift @xmath116 , and a time dependent @xmath115 piece which , for @xmath112 , can be written in terms of fields obeying the 4drw equation . once the appropriate set of perturbation fields @xmath113 is given , and their relation to the 4drw equation established for @xmath112 , we may adapt to the 4drw equation the techniques used to prove boundedness of solutions of the scalar wave equation , in order to analyze the behavior of the @xmath1 fields . as an example , the result of kay and wald @xcite was used in @xcite to prove ( [ bounds1 ] ) in the schwarzschild case , and is adapted here to prove that ( [ bounds1 ] ) holds also for positive @xmath0 . we can go further and take advantage of the growing literature on decay of solutions of the scalar wave equation on s(a)ds backgrounds , as many of these results are expected to hold also for ( [ 4drwe ] ) . specific time decay results for the 4drw equation , somewhat expected from price s result @xcite , can be found in @xcite ( see also the recent preprint @xcite ) . putting together the bijection ( [ i m ] ) , the above description of the stationary ( @xmath57 ) and dynamic ( @xmath66 ) pieces of @xmath1 , and the time decay results , the following picture emerges for a perturbed schwarzschild ( sds ) black hole : a generic perturbation contains a mass shift , infinitesimal angular momenta @xmath117 and dynamical degrees of freedom ; at large times the dynamical degrees of freedom decay and what is left is a linearized kerr ( kerr ds ) black hole around the background schwarzschild ( sds ) solution . + through the paper , calculations are carried leaving @xmath0 unspecified whenever possible , and specializing when necessary . among the many current treatments of linear perturbations of spherically symmetric spacetimes , we have made heavy use of the excellent paper @xcite , which we found particularly well suited to our approach . a spherically symmetric space - time is a warped product @xmath118 of a lorentzian two - manifold @xmath119 with the unit sphere @xmath120 , for which we will use the standard angular coordinates @xmath121 : @xmath122 the form of the metric ( [ ssm ] ) implies that @xmath123 inherits the isometry group @xmath124 of @xmath125 as an isometry subgroup . here @xmath126 are the proper rotations and @xmath127 is the antipodal map @xmath128 . since @xmath126 acts transitively on @xmath51 , we find that @xmath129 , this is why @xmath119 is called the ( @xmath126 ) _ orbit space_. + equation ( [ ssm ] ) exhibits our index conventions , which we have adopted form ref @xcite : lower case latin indexes are used for tensors on @xmath130 , upper case latin indexes for tensors on @xmath51 , and greek indexes for space - time tensors . we will furthermore assume that @xmath131 tensor fields _ introduced _ with a lower @xmath51 index ( say @xmath132 ) and _ then shown with an upper @xmath51 index _ are assumed to have been acted upon _ with the unit @xmath51 metric inverse @xmath133 _ , ( i.e. , @xmath134 ) , and similarly for upper @xmath51 indexes moving down . @xmath135 and @xmath136 are the covariant derivative , volume form ( any chosen orientation ) and metric inverse for @xmath119 ; @xmath137 and @xmath138 are the covariant derivative and volume form on the unit sphere , for which we assume the standard orientation @xmath139 . + as an example , in terms of the differential operators @xmath140 and @xmath137 , the laplacian on scalar fields reads @xmath141 the einstein field equation , as well as its linearized version around a particular solution , is expressed as an equality among symmetric tensor fields . the metric perturbation @xmath7 may be subjected to gauge transformations of the form ( [ gt2 ] ) . this is why we are interested in the decomposition on a spherically symmetric spacetime of covector fields ( such as @xmath142 ) and symmetric rank two tensor fields such as @xmath7 . + we will assume all tensor fields on @xmath102 are smooth . as a consequence their components will be square integrable on @xmath51 and can be expanded using a real orthonormal basis of scalar spherical harmonics @xmath143 where @xmath53 numbers an orthonormal basis @xmath73 of the @xmath144-dimensional eigenspace with eigenvalue @xmath52 of the laplace - beltrami operator @xmath145 on scalar functions ( @xmath146 ) . an explicit choice for the @xmath57 subspaces is @xmath147 and @xmath148 we denote @xmath149 the @xmath50 subspace of @xmath150 and @xmath151 . + a covector field on @xmath102 @xmath152 contains the @xmath51 covector @xmath153 which , according to proposition 2.1 in @xcite , can be uniquely decomposed as @xmath154 where @xmath155 . this last condition implies that @xmath156 is dual to the differential of an @xmath157scalar , @xmath158 . it then follows that , introducing @xmath159 and @xmath160 for later convenience , @xmath161 where the _ odd _ piece of @xmath162 is @xmath163 and its _ even _ piece is @xmath164 for a given covector field @xmath162 , the scalar fields @xmath165 are unique up to an @xmath51-constant , thus they are unique if we require that they belong to @xmath166 @xmath167 a condition that we will assume . the symmetric tensor field @xmath168 @xmath169 contains two @xmath51 covector fields @xmath170 and a symmetric @xmath51 tensor field @xmath171 . note that @xmath172 and @xmath173 are covector fields on @xmath174 parametrized on @xmath51 . + using proposition 2.2 in @xcite and the fact that there are no transverse traceless symmetric tensor fields on @xmath51 @xcite , we find that the @xmath51 symmetric tensor @xmath171 in ( [ std1 ] ) can be uniquely decomposed into three terms : @xmath175 introducing @xmath176 , @xmath177 and @xmath178 we arrive at ( c.f . , @xcite , section iv.a ) + a generic smooth metric perturbation admits the following decomposition : + @xmath179 where the _ odd _ piece of @xmath180 is @xmath181 and the _ even _ piece is @xmath182 \end{array } \right).\ ] ] the proof of the following lemma follows from straightforward calculations : [ kernel ] * the kernel of the map @xmath183 defined in ( [ pert- ] ) is the set of @xmath173 and @xmath184 of the form @xmath185 this implies that @xmath173 and @xmath184 are unique if they are required to belong to @xmath166 and @xmath186 respectively : @xmath187 * the kernel of the map @xmath188 defined in ( [ pert+ ] ) is characterized by @xmath189 @xmath190 thus , the fields @xmath191 are uniquely defined if we require that @xmath192 and @xmath193 . from now on we will assume the required conditions for uniqueness of @xmath194 and @xmath195 . + the linearized ricci tensor @xmath196 admits a decomposition analogous to ( [ std1])-([pert+ ] ) . given that @xmath157scalar fields , divergence free covector fields ( which are all of the form @xmath197 ) and transverse traceless symmetric tensors on @xmath51 span inequivalent @xmath198 representations , and that the linear map @xmath199 is @xmath198 invariant , this map can not mix odd and even sectors @xcite . this implies that @xmath200 is a linear functional of @xmath201 only , and similarly @xmath202 depends only on @xmath203 . + note from ( [ l=1 ] ) that @xmath204 @xmath205 , is a basis of killing vector fields on @xmath51 generating rotations around orthogonal axis , normalized such that the maximum length of their orbits is @xmath206 . the square angular momentum operator is the sum of the squares of the lie derivatives along these killing vector fields : @xmath207 this operator commutes with the maps @xmath183 and @xmath208 ( and similarly in the even sector ) . as a consequence , the @xmath49 piece of @xmath209 depends only on the @xmath49 piece of @xmath210 ( see equation ( [ exp1 ] ) ) : @xmath211 and similarly in the even sector . note from ( [ pert - l ] ) and ( [ kvfs ] ) that the odd @xmath59 modes add up to @xmath212 these @xmath59 perturbations correspond to infinitesimal rotation , i.e. , to deformations towards a stationary kerr solution . + the @xmath213 mode is defined in a way analogous to ( [ pert - l ] ) , i.e. , keeping a single term in the spherical harmonic expansion of the even fields @xmath191 . it is important to note that @xmath214 the different behavior under parity is the signature that distinguishes odd from even modes . the schwarzschild / schwarzschild ( anti ) de - sitter ( s(a)ds ) is the only spherically symmetric solution of the vacuum einstein equation with a cosmological constant @xmath0 : @xmath215 @xmath216 the ricci tensor of the lorentzian metric @xmath217 . the manifold is @xmath218 , the metric ( c.f . equation ( [ ssm ] ) ) @xmath219 the constant @xmath39 is the mass of the solution , @xmath220 in ( [ sads ] ) gives the minkowski ( @xmath6 ) , de sitter ( @xmath221 ) and anti de sitter ( @xmath222 ) spacetimes . @xmath223 in ( [ sads ] ) corresponds to a schwarzschild black hole if @xmath6 , a schwarzschild de sitter ( sds ) black hole if @xmath224 and @xmath225 , and sads black hole if @xmath222 . + the killing vector field @xmath226 is timelike in the open sets defined by @xmath227 and spacelike in the open sets defined by @xmath228 . the null hypersurfaces of constant _ positive _ @xmath40 where @xmath229 are the horizons , they cover the curvature singularity at @xmath230 . + in any open set where @xmath231 we may define a `` tortoise '' radial coordinate @xmath232 by @xmath233 and a coordinate @xmath78 through @xmath234 the metric in static coordinates @xmath61 is @xmath235 the schwarzschild ( @xmath6 ) and the sads ( @xmath236 ) black holes have a single horizon at @xmath237 , satisfying @xmath238 in terms of which @xmath239 these black holes have a non - static region i defined by @xmath240 and a static region ii defined by @xmath241 . + the sds black holes are those for which @xmath242 ( @xmath243 has single real root when @xmath244 , and this root is negative ) . for sds black holes @xmath243 has one negative ( @xmath245 ) and two positive roots @xmath246 , @xmath247 , with @xmath248 as @xmath249 , and @xcite @xmath250 there is a non - static region i defined by @xmath240 adjacent to a static region ii ( @xmath251 ) , and a further non - static region iii defined by @xmath252 . + this paper focuses on the stability of the static region ii of schwarzschild and s(a)ds black holes . let @xmath28 be the function @xmath253 @xmath28 is smooth in i @xmath254 ii ( i.e. , @xmath255 for sds , @xmath256 for schwarzschild and sads ) , since @xmath243 is smooth with a simple zero at @xmath237 and no zeros in i and ii . + consider the following solution of ( [ rs ] ) @xmath257 the most general solution is obtained by adding ( possibly different ) constants to the left and right of @xmath237 , however , for @xmath232 as in ( [ srs ] ) , the function @xmath258 is smooth in i @xmath254 ii , and monotonically growing , so it has an inverse @xmath259 . introduce @xmath260 in addition to @xmath261 above , then @xmath262 now let @xmath263 note that @xmath264 and @xmath265 , therefore ( [ sads ] ) is equivalent to @xmath266 and @xmath267 . we may now take two extra copies of i and ii ( call these @xmath268 and @xmath269 ) and define @xmath270 the black hole metric ( [ sads ] ) in @xmath271 is again given by equation ( [ uvmetric ] ) , except that now @xmath272 . it can be checked that ( [ uvmetric ] ) is smooth on @xmath51 times the open region of the @xmath273 plane defined by @xmath274 ( @xmath275 for sds ) . this region contains two copies of i and two copies of ii . since @xmath40 is a function of the product @xmath276 , the metric ( [ uvmetric ] ) has the discrete @xmath277 symmetry @xmath278 under which @xmath279 and @xmath280 . the @xmath277 invariant set @xmath281 is a sphere of radius @xmath282 , called _ bifurcation sphere_. + integrating ( [ rs ] ) in region ii we find that , for @xmath6 , after choosing an integration constant , @xmath283 for @xmath236 the integration constant can be chosen such that @xmath284 and for @xmath285 and @xmath251 , @xmath286 it follows that , in region ii of a schwarzschild or sds black hole , @xmath287 ( which corresponds to the entire quadrants @xmath288 , @xmath267 and @xmath289 , @xmath272 ) . for sads , on the other hand , @xmath290 , therefore @xmath291 in ii , and @xmath292 in @xmath269 . + the above construction gives the penrose - carter diagrams in figure 1 . in the ads case ( right side of the figure ) , there is a conformal time like boundary corresponding to @xmath291 in ii , and @xmath292 in @xmath269 . the conformal boundary of region ii is replaced in the schwarzschild case by null infinity , and in the sds case by the cosmological horizon ( left side of the figure ) . for the sds black hole it is possible to follow a procedure similar to the one outlined above that gives a further extension with a bifurcation sphere at @xmath293 , two copies of region iii , and an extra copy of ii . the maximal analytic extension of sds contains infinitely many copies of i , ii , and iii @xcite . singularities , the thick lines are past and future event horizons -the @xmath294 and @xmath295 axis in ( [ uvmetric])- , they intersect at the bifurcation sphere . the thin lines correspond to null infinity ( the cosmological horizon ) . + right : penrose - carter diagram for a sads black hole . the dotted lines are the singularities at @xmath230 , the thick lines are the past and future event horizons -the @xmath294 and @xmath295 axis intersecting at the bifurcation sphere- . the thin time - like lines correspond to null infinity . , width=566 ] if we use the coordinates @xmath296 , the scalar wave equation ( [ lap ] ) acquires the simple form @xmath297 ( r\phi),\ ] ] and ( [ 4drwe ] ) reduces to @xmath298 = \left [ { \partial}_t^2 - { \partial}_{r^*}^2 - f \left ( \frac{\hd^a \hd_a}{r^2 } + \frac{6m}{r^3 } \right ) \right ] ( r\phi),\ ] ] that is , @xmath299 where @xmath300 and @xmath301 if we expand @xmath101 in spherical harmonics , @xmath302 and use this in equations ( [ 2 + 2])-([v12a ] ) , we find that ( [ 4drwe ] ) is indeed equivalent to the set of equations ( [ rwe ] ) , extended to include @xmath57 . + note that , although the above equations are formally similar for different values of @xmath0 , @xmath287 as @xmath40 spans region ii of the schwarzschild and sds black holes , but is restricted to @xmath303 in region ii of the sads black hole . the reason why equation ( [ 4drwe ] ) for sads is equivalent to a system of wave equations with a potential in _ a half _ of a two dimensional minkowski space , is that region ii of sads is not globally hyperbolic , but has a conformal timelike boundary at @xmath304 ( equation ( [ srnl ] ) ) . the problem of defining the dynamics imposed by hyperbolic equations ( such as ( [ 4drwe ] ) , ( [ rwe ] ) and ( [ ze ] ) ) in a non globally hyperbolic static spacetime ( either sads or its two dimensional orbit space sads@xmath305 ) , that is , giving unique solutions from initial data at a surface @xmath306 transverse to the timelike killing vector field @xmath307 , has been addressed in the series of articles @xcite , @xcite and @xcite . as expected , the dynamics is unique only within the domain of dependence of the support of the initial datum ; outside it , it depends on the self adjoint extension that we choose for the operator @xmath308 which is roughly our choice of boundary conditions at @xmath304 . + for the zerilli equation ( [ ze ] ) of an sads black hole , we have found that there is a choice of boundary conditions at @xmath304 under which even perturbations that preserve the ads asymptote , grow exponentially with time . for this choice , sads is unstable . there is an infinite set of possible boundary conditions for equation ( [ ze ] ) in sads@xmath305 , we are currently analyzing the dynamics and stability of sads black holes under different choices @xcite . there are many sources for the well know solution of the lee around a schwarzschild background . two historically relevant references are @xcite , where the gauge invariance of rw and zerilli potentials was established , and @xcite , where a `` covariant '' formulation using arbitrary coordinates _ for the orbit space _ in order to study , e.g. , waves crossing the horizon was developed ( this should more properly be called `` 2d covariant approach '' ) . more recently , the 2d covariant approach was generalized to gr black holes with constant curvature horizons in arbitrary dimensions and including a cosmological constant in a series of papers by ishibashi and kodama ( see , e.g. , @xcite and @xcite ) . we find the 2d covariant approach in reference @xcite particularly well adjusted to our purposes as , although restricted to the dynamical @xmath66 perturbations , avoids unnecessary expansions in harmonic modes . section v in @xcite is devoted to the schwarzschild black hole , we generalize the exposition there to @xmath69 below . the effect of the diffeomorphism generated by the vector field @xmath23 on the first order variation of a tensor @xmath27 is @xmath309 . in particular , the effect on @xmath310 , @xmath311 defines an equivalence relation where @xmath312 iff there exists a covector field @xmath162 such that ( [ gt ] ) holds . to measure the strength of the perturbation we will analyze gauge invariant fields , i.e. , fields that depend only on the class @xmath32 $ ] of a metric perturbation under the equivalence relation defined above . in this section we show how to parametrize the set of classes @xmath32 $ ] by means of gauge invariant fields and how to choose a class representative ( gauge fixing ) . + given a generic vector field ( [ vd])-([0l0 ] ) we find that @xmath313 and @xmath314 where it should be kept in mind that @xmath315 and @xmath316 belong to @xmath166 . these equations imply that the odd ( even ) piece of @xmath162 affects the odd ( even ) piece of @xmath7 in ( [ gt ] ) . let us analyze the effect of gauge transformations in the odd sector . inserting @xmath317 , @xmath318 in ( [ gto ] ) ( @xmath319 are coordinates of the orbit manifolds , @xmath73 orthonormal real spherical harmonics ) , defining @xmath320 and splitting similarly all the other fields , we find from ( [ pl1- ] ) , ( [ gt ] ) and ( [ kvfs ] ) that @xmath321 and also that @xmath322 this last equation implies that : i ) @xmath323 is a gauge invariant field and ii ) there is a gauge ( commonly known as the regge - wheeler gauge ) where the @xmath324 piece of the odd metric perturbation assumes the form @xmath325 a calculation of the lee ( [ lee ] ) using ( [ pert - rw ] ) gives , in agreement with equations ( 31 ) in @xcite , @xmath326\\ \dot r_{ab } - \lambda h_{a b } & = \widehat { \epsilon}_{(a}{}^c \hd_{b ) } \hd_c ( \td^a h_a ) \end{aligned}\ ] ] where @xmath327 in deriving equations ( [ dr1])-([f ] ) we have not made any assumptions on @xmath328 in ( [ pert - rw ] ) , so these calculations also hold for the @xmath59 mode given in ( [ pl1- ] ) and ( [ kvfs ] ) if we replace @xmath328 with @xmath329 . in this case , however , @xmath330 and also @xmath331 , so the lee for the odd @xmath59 modes can entirely be written in terms of the field @xmath332 which is invariant under the gauge transformation ( [ gt-1 ] ) . thus , for the odd @xmath59 mode we find @xmath333\\ \dot r_{ab } - \lambda h_{a b } & = 0.\end{aligned}\ ] ] using the facts that the kernel of the operator @xmath334 is the @xmath58 mode and the kernel of @xmath335 are the @xmath57 modes , we arrive at the lee ( [ lee ] ) in the odd sector is equivalent to the system @xmath336 let us treat first the equations for @xmath59 modes . the general solution of equation ( [ l1-e ] ) is @xcite @xmath337 @xmath338 a gauge invariant constant and @xmath339 an arbitrary function that we recognize from ( [ gt-1 ] ) as `` pure gauge '' . for the schwarzschild-(a)ds space - time in schwarzschild coordinates , @xmath340 , @xmath341 , and equation ( [ sol-1 ] ) reads @xmath342 if we take , e.g. , @xmath343 , choose the gauge @xmath344 , @xmath345 , and insert the above equation in ( [ pl1- ] ) , we obtain @xmath346 which we recognize as the first order taylor expansion around @xmath347 of the kerr-(a)ds metric with angular momentum @xmath348 in boyer - lindquist coordinates . this proves our previous assertion that @xmath59 odd modes correspond to displacements within the stationary kerr family of black holes . + consider now the @xmath324 odd lee , equations ( [ 1 ] ) and ( [ two ] ) . for the schwarzschild-(a)ds background equation ( [ two ] ) reads @xmath349 and , as noticed in @xcite , implies ( [ 1 ] ) ( proof : @xmath350 implies @xmath351 since @xmath352 ) . on the other hand , equation ( [ 2p ] ) implies ( _ but is not equivalent to ! _ ) @xmath353 , a condition that , from the definition of @xmath354 , equations ( [ lap ] ) and ( [ f ] ) and the background equation @xmath355 is seen to be equivalent to @xmath356 interestingly enough , ( [ l1-e ] ) and ( [ f1 ] ) imply that @xmath357 which , using ( [ lap ] ) is easily seen to also satisfy equation ( [ rwf ] ) . we conclude that the lee implies that @xmath358 back to ( [ 1])-([two ] ) , we note that the solution of ( [ 1 ] ) is @xmath359 for some scalar field @xmath360 . this implies that @xmath361 inserting ( [ ha ] ) in ( [ 2p ] ) gives @xmath362 = 0.\ ] ] the general solution to this equation is @xmath363 and we may ( and will ) choose @xmath364 , which gives @xmath365 \phi = - [ 2 + \mathbf{j}^2 ] \phi,\ ] ] together with @xmath366 which , using again ( [ lap ] ) and ( [ rab ] ) , is seen to be equivalent to the 4drw equation @xmath367 equation ( [ rwep ] ) is equivalent to the standard form ( [ rwe ] ) after decomposing @xmath101 in modes as in ( [ 4drf ] ) . + we can gather our results concerning the odd sector of the lee in the following : [ oddsol ] consider the odd sector of the lee around a schwarzschild-(a)ds background : * the solution of the @xmath115 piece of the metric perturbation in the regge - wheeler gauge is given by equation ( [ pert - rw ] ) , where the gauge invariant field @xmath328 is as in equation ( [ ha ] ) and @xmath101 satisfies the 4drw equation ( [ rwep ] ) . equations ( [ pert - rw ] ) and ( [ ha ] ) are equivalent to ( [ csp ] ) . * the solution of the @xmath59 piece is given in equations ( [ pl1- ] ) and ( [ sol-1b ] ) . in this last equation @xmath338 are three gauge invariant constants and @xmath339 three arbitrary gauge functions . * there is a bijection between the space @xmath368 of smooth odd solutions of the lee mod gauge transformations and the set @xmath369 * the lee implies that the gauge invariant field @xmath370 ( defined in equations ( [ f ] ) and ( [ f1 ] ) ) satisfies the 4drw equation ( [ rwef ] ) . the equivalence of ( [ pert - rw ] ) and ( [ ha ] ) to ( [ csp ] ) is checked by a straightforward calculation . ( iii ) follows immediately from ( i ) and ( ii ) . note also that the relation ( [ fp ] ) explains why the fields @xmath354 and @xmath101 , which belong to @xmath186 , satisfy the same wave equation : the operators @xmath371 and @xmath372 $ ] commute , and @xmath372 $ ] is invertible in @xmath186 ( on scalar fields , @xmath373 and on arbitrary tensor fields @xmath374=0 $ ] , since @xmath375=0 $ ] for any killing vector field @xmath376 ) . + for the purposes of a non - modal analysis , lemma [ oddsol].(iii ) offers a more appropriate parametrization of the dynamical sector of the odd perturbations than the infinite set of @xmath377 s . however , unlike the @xmath59 parameters @xmath378 , no clear geometrical meaning can be attached to @xmath101 in ( [ rwep ] ) , beyond that of being a potential for solutions of the lee , equation ( [ csp ] ) . consider now the curvature scalars in ( [ curvaturescalars ] ) . in this section we show that the first order variation @xmath379 of @xmath380 associated to a perturbation @xmath381 \in \mathcal { l}_-$ ] contains all the gauge invariant information about @xmath210 . in particular , @xmath101 and the @xmath338can be recovered from @xmath379 which , unlike @xmath101 , has a distinct geometrical meaning . note that , since @xmath382 for the s(a)ds geometries , @xmath383 is gauge invariant . + @xmath383 can be obtained from the set of equations ( 3 ) and ( 29 ) in @xcite . the calculations are tedious and not particularly illuminating . the result is @xmath384 as an example , for the choice @xmath343 in ( [ pl1-b ] ) , the @xmath59 piece of @xmath385 in ( [ qd ] ) is @xmath386 which agrees with the first order taylor expansion of @xmath380 for the kerr-(a)de - sitter black hole in boyer - lindquist coordinates around @xmath347 , as anticipated . for arbitrary @xmath338 s , equation ( [ q1a ] ) generalizes to @xmath387 combining equations ( [ fp ] ) , ( [ qd ] ) and ( [ q1b ] ) gives @xmath388 which generalizes to @xmath69 equation ( 22 ) in @xcite . [ biy- ] let @xmath381 \in \mathcal { l}_-$ ] and @xmath389\right)$ ] be the first order variation of @xmath380 for the perturbation @xmath381 $ ] : * the field @xmath390 is in @xmath391 and satisfies the 4drw equation @xmath392 ( r^5 \dot q_- ) = 0\ ] ] * the map @xmath381 \to \dot q_-\left([h_{{\alpha}{\beta}}^{(-)}]\right)$ ] is invertible : it is possible to construct a representative of @xmath381 $ ] from @xmath389\right)$ ] . * equation ( [ qdt ] ) proves that @xmath393 . this is a consequence of the facts that there are no odd @xmath58 modes , only odd modes contribute to @xmath383 , and @xmath394\right)= \dot q_-\left ( \mathbf{j}^2[h_{{\alpha}{\beta}}^{(-)}]\right)$ ] . alternatively , by birkhoff s theorem in a cosmological background @xcite , the only possible spherically symmetric perturbation of a schwarzschild-(a)ds black hole amounts to a change of the black hole mass , and this does not affect the unperturbed value @xmath382 . since @xmath395 commutes with the wave operator in ( [ rwef ] ) , it follows from ( [ qd ] ) and lemma [ oddsol].(iv ) that @xmath390 satisfies ( [ rweqd ] ) . * according to equation ( [ qdt ] ) , from the @xmath59 coefficients in the spherical harmonic expansion of @xmath383 we obtain the constants @xmath338 . this allows us to construct the @xmath59 piece of the @xmath396 representative of @xmath381 $ ] in ( [ sol-1 ] ) and use it in ( [ pl1- ] ) . the orthogonal projection of @xmath397 onto @xmath186 is related to @xmath101 through the operator @xmath398 ( equation ( [ qdt ] ) ) . this operator is invertible in @xmath186 , so we can recover @xmath101 from @xmath389\right)$ ] and use it in ( [ ha ] ) or ( [ csp ] ) to construct the regge - wheeler representative ( [ pert - rw ] ) of the @xmath115 piece of @xmath381 $ ] . + equation ( [ qdt ] ) defines a bijection between the set @xmath399defined in lemma [ oddsol].(iii ) and the set @xmath400\right ) \ ; \bigg| \ ; h_{{\alpha}{\beta}}^{(- ) } \text { is a solution of the lee } \bigg\}\ ] ] this bijection implies that @xmath383 contains all the relevant ( i.e. , gauge invariant ) information on the metric perturbation that gave rise to it . the invertible relations @xmath401 and @xmath402 explain why all these fields obey the same way equation . note that the addition of an @xmath59 piece @xmath403 to the potential @xmath101 satisfying a 4drw equation would be irrelevant , as its contribution to @xmath328 would vanish : @xmath404 . having found that the scalar gauge invariant field @xmath379 that measures the distortion of the curvature encodes all the information on a given odd perturbation , it is natural to define the strength of the perturbation as the magnitude of this field . a key additional feature of @xmath383 is the fact @xmath390 satisfies equation ( [ 4drwe ] ) ( see ( [ rweqd ] ) in theorem [ biy-].(i ) ) . this will be used to prove that the magnitude of @xmath383 , and thus the strength of the perturbation , can be bounded on the entire outer static region . this fulfills the requirements of our proposed notion of non - modal linear stability . it is important to note that theorem [ biy- ] applies to arbitrary smooth perturbations , whereas any boundedness or fall - off condition will require a restriction to perturbations evolving from data that behave properly as @xmath75 ( @xmath405 ) in the asymptotically flat ( de sitter ) case . in the @xmath6 case , a simple pointwise boundedness statement for @xmath110 can be made by noting that the proof of boundedness of a klein gordon field in @xcite holds for the 4drw equation : [ odd-0 ] for any smooth solution of the odd lee which has compact support on cauchy surfaces of the kruskal extension @xmath406 of the schwarzschild space - time ( figure [ figurita ] ) , there exists a constant @xmath407 such that @xmath408 for @xmath409 . from ( [ qdt ] ) , @xmath410 , where @xmath411 is a constant that depends on the @xmath338 s and the field @xmath412 satisfies the 4drw equation ( [ rwep ] ) , so we only need concentrate on this field . the similarities between the 4drwe equation and the massive klein gordon equation dealt with in @xcite allow us to proceed by adapting the proof of theorem 1 in @xcite . the @xmath277 symmetry arguments in @xcite showing that this theorem reduces to the _ intermediate case _ ( treated in the appendix in @xcite ) apply verbatim to equation ( [ rwep ] ) . the intermediate case is defined by adding the requirements that @xmath413 and its @xmath27 derivative ( in coordinates @xmath414 , where @xmath415 and @xmath416 ) vanish on the bifurcation sphere ( refer to section [ bss ] ) . there remains to check that the proof in the appendix in @xcite applies to the wave equation ( [ rwep ] ) . to this end , we use ( [ lap2])-([v12a ] ) to cast ( [ rweqd ] ) in the exterior kruskal wedge as @xmath417 where @xmath418 with @xmath232 defined in ( [ rs ] ) , @xmath419 for the klein gordon equation dealt with in @xcite , the differential equation assumes this same form with @xmath420 where @xmath421 is the square of the mass of the klein gordon field ( which appears with a wrong sign in equation ( 1 ) in @xcite , but with the correct sign in the equations in the appendix ) . however , the proof in the appendix in @xcite does not make use of the explicit forms of @xmath422 and @xmath423 , but only on the facts that these functions are bounded on the exterior wedge @xmath44 , and that @xmath308 is a positive definite self adjoint operator on @xmath424 . since @xmath425 and @xmath426 defined in ( [ a])-([v12 ] ) are bounded for @xmath409 , and @xmath308 is positive definite _ on the @xmath115 subspace of @xmath427 _ , the proof in the appendix in @xcite applies to the wave equation ( [ rweqd ] ) for @xmath428 . the intermediate case then follows , and so does the analogue of theorem 1 in @xcite . note that the proof in @xcite shows that for the klein gordon field @xmath429 holds on the domain of outer communications . although the weaker statement @xmath430 has been made in @xcite , the stronger form was used in this proof . two key similarities between the extension ( [ uvmetric ] ) for @xmath69 and the kruskal extension of the @xmath6 schwarzschild black hole ( refer to section [ bss ] and figure 1 ) are : i ) the @xmath277 isometry exchanging i and @xmath268 and ii and @xmath269 , and ii ) the fact that @xmath282 is a simple root of @xmath243 , which implies that the asymptotic behavior of fields vanishing at the bifurcation sphere is that in equation ( a1 ) in @xcite . this allows us to prove the following [ odd+ ] for any smooth solution of the odd lee which has compact support on cauchy surfaces of the extended @xmath406 sds black hole , there exists a constant @xmath407 such that @xmath431 ( equivalently , @xmath432 a constant ) for @xmath251 . as in the proof of theorem [ odd-0 ] , and in view of the above comments , we need only prove the intermediate case for @xmath412 . this field obeys the equation @xmath433 where ( see ( [ al ] ) ) @xmath434 with @xmath287 , @xmath435 in view of ( [ rhrc ] ) and the condition @xmath66 , @xmath436 and @xmath437 are bounded in region ii ( @xmath251 ) and @xmath438 , thus @xmath439 is a positive definite self adjoint operator on @xmath424 , and the proof follows as in theorem [ odd-0 ] . the stability proofs above use the facts that the operators ( [ a ] ) and ( [ a+l ] ) are self adjoint and positive definite in the region of interest . for negative cosmological constant , the operator acts as @xmath440 but on functions defined for @xmath290 , which is the outer static region in this case . this operator is only _ formally _ self adjoint ( i.e. , if we ignore boundary terms when integrating by parts ) , we need to specify boundary conditions at @xmath304 to properly define a domain where the operator is self adjoint . there are different options , and the positivity or not of the resulting operator depends on the chosen boundary condition @xcite . the stability for dirichlet boundary conditions was established in @xcite . the effect of the gauge transformation ( [ gt])-([gte ] ) in the even sector ( [ pert+ ] ) is @xmath441 \end{array } \right).\ ] ] since @xmath315 and @xmath172 belong to @xmath166 , and @xmath193 , the @xmath57 modes require a separate treatment . for the @xmath58 mode @xmath442 we _ partially _ fix a gauge by requiring @xmath443 together with the transverse condition @xmath444 @xcite ( note that a further gauge transformation with a gauge field @xmath445 would preserve these two conditions . ) dropping the primes , the perturbation in such a traceless gauge reads @xmath446 for the traceless symmetric orbit space tensor @xmath447 we use the identity @xcite @xmath448 , \;\;\ ; c_a^{(\ell=0 ) } = { h}_{ab}^{(\ell=0,t ) } \td^b r,\ ] ] in terms of which , the residual gauge transformation along the field ( [ res0 ] ) gives @xmath449 in conclusion , we assume the form ( [ pert+t])-([ttos ] ) for the metric perturbation , where @xmath450 is equivalent to @xmath451 defined in ( [ gt0z ] ) . for @xmath59 modes @xmath452 we may choose the gauge field such that @xmath453 and @xmath454 . this will partially fix an orbit space transverse gauge , leaving a perturbation of the form @xmath455 where , as in the @xmath58 sector , @xmath456 , \;\;\ ; c_a^{(\ell=1 ) } = { h}_{ab}^{(\ell=1,t ) } \td^b r,\ ] ] a residual gauge transformation along a field ( [ vec+ ] ) satisfying @xmath457 preserves the form ( [ pert+rw])-([tt1s ] ) . for @xmath458 , equation ( [ pert+gauge ] ) @xmath459 has two implications ( compare with the discussion following ( [ pert - gt ] ) ) : i ) the fields @xmath460 are gauge invariants ; and ( ii ) there is a ( unique ) gauge ( the regge - wheeler gauge ) where the @xmath115 piece of the even metric perturbation assumes the form @xmath461 a calculation of the lee ( [ lee ] ) using ( [ rwe ] ) gives , in agreement with equations ( 31 ) in @xcite , the following components for @xmath462 : @xmath463\\ \dot r_{ab } - \lambda h_{a b } & = -\frac{1}{2 } \left ( \hd_a \hd_b h - \tfrac{1}{2 } \widehat g_{ab } \hd^c \hd_c h \right ) + \widehat g_{ab } \left [ \td^a ( r h_{ab } \td^b r ) \nonumber \right . \\ & \;\;\;\ ; \left . -\frac{r}{2 } ( \td^a r ) \td_a h - \frac{1}{4 } \td^c \td_c ( r^2 \mathcal{j } ) - \frac{1}{4 } \hd^c \hd_c(h+ \mathcal{j } ) - \lambda \frac{r^2}{2 } \mathcal{j } \right ] , \label{even3}\end{aligned}\ ] ] where @xmath464 is the ricci scalar of the orbit manifold and @xmath465 from part ii ) of lemma [ kernel ] ( applied now to the symmetric tensor @xmath462 ) we conclude that ( [ even3 ] ) implies @xmath466 , then as in ( [ ttos ] ) we introduce @xmath467 which gives @xmath468.\ ] ] and @xmath469 for @xmath470 , equation ( [ even2 ] ) is equivalent to @xmath471 . contracting this equation with the orthogonal vectors @xmath472 and @xmath473 and using ( [ rab ] ) gives @xcite : @xmath474 introducing @xmath475 we write ( [ dz1 ] ) as @xmath476 } = 0\ ] ] and equation ( [ eqc ] ) as @xmath477 now contract ( [ even3 ] ) with @xmath478 , this gives @xmath479 \mathcal{j } = 0.\ ] ] finally , contracting the @xmath480 trace - free part of ( [ even1 ] ) with @xmath472 and using ( [ 41c ] ) we arrive at @xmath481 - \hd^c \hd_c z_a = 0\ ] ] it is interesting to note that equations ( [ 41a])-([41d ] ) look _ formally _ identical to the @xmath6 case , equations ( 41a)-(41d ) in @xcite , @xmath0 appears only implicitly through @xmath480 and its levi - civita derivative @xmath140 . in deriving equations ( [ even1])-([even3 ] ) we made no assumptions on @xmath482 and @xmath483 in ( [ pert - rw ] ) , so these calculations apply to the @xmath58 mode ( [ pert+t ] ) if we replace @xmath482 with @xmath484 and set @xmath485 . equation ( [ even2 ] ) is void in this case , whereas equation ( [ even3 ] ) reduces to @xmath486 , whose solution is @xmath487 in schwarschild coordinates @xmath85 the residual gauge freedom ( [ gt0z ] ) implies that @xmath488 is defined up to an arbitrary additive function @xmath489 ( choose @xmath490 to match ( [ gt0z ] ) ) . replacing ( [ ca0 ] ) in ( [ even1 ] ) and ( [ even3 ] ) we find that , working in @xmath85 coordinates , @xmath491 . this gives @xmath492 , @xmath493 and @xmath494 . choosing the gauge @xmath495 we recognize this perturbation as a shift @xmath496 in the mass treated to first order in @xmath497 . this was to be expected from birkhoff s theorem . in conclusion , we can choose a gauge such that @xmath498 the perturbation class is characterized by the parameter @xmath116 . we use again equations ( [ even1])-([even3 ] ) with the replacements @xmath499 and @xmath500 , and find that the general solution to these equations can be set to zero using the residual gauge freedom ( [ rgf1 ] ) ( see @xcite ) . this implies that the even @xmath59 sector is void . the results of the previous section are gathered in the following the lee ( [ lee ] ) in the even sector is equivalent to the system of equations ( [ za])-([41d ] ) and ( [ md ] ) . the system ( [ 41a])-([41d ] ) of lee for the @xmath115 sector was first solved by zerilli in @xcite , the addition of a cosmological constant was considered in @xcite . in this section we generalize to the case @xmath69 the derivation in @xcite of the zerilli equation . + equation ( [ 41a ] ) implies that there is a scalar field @xmath501 , defined up to an additive function @xmath502 , @xmath503 , such that @xmath504 from ( [ 41b ] ) and ( [ 41c ] ) @xmath505 from ( [ 41d ] ) ( [ zz ] ) and the above equation @xmath506 since all fields above belong to @xmath186 , we may choose @xmath507 such that the term on the right vanishes . from now on we assume this choice , which gives @xmath508 applying @xmath509 to ( [ 43 ] ) and combining with ( [ 42 ] ) yields @xmath510 the zerilli field @xmath511 is introduced to eliminate first derivatives from ( [ zeq ] ) and reduce it to a two dimensional wave equation : @xmath512 \psi=0.\end{gathered}\ ] ] this is the zerilli equation , first obtained for @xmath6 in @xcite , and generalized to schwarzschild-(a)ds in @xcite . the non - local operator @xmath513 is well defined on @xmath186 ; the zerilli equation was derived within the context of a modal approach to the problem , in which @xmath514 is expanded in spherical harmonics @xmath515 and this operator reduces to @xmath516 in the @xmath50 subspace , and it is therefore suitable to perform explicit calculations . if we use a tortoise radial coordinate @xmath232 , we find that ( [ zerilli ] ) is equivalent to the standard form ( [ ze])-([zp ] ) of the equation in the original references @xcite @xcite . from the @xmath517 field ( and therefore from the zerilli field ) it is possible to reconstruct @xmath482 and @xmath483 by tracing back the above equations . the result is @xcite @xcite : @xmath518 \\ h_{ab } & = 2 \left ( \hd^c \hd_c + 2 - \frac{6m}{r } \right)^{-1 } \left [ \td_a \td_b ( r\zeta ) -\frac{\tilde g_{ab}}{2 } \td^c \td_c ( r\zeta ) \right ] \label{h } \end{aligned}\ ] ] the even sector lee is equivalent to the set ( [ zeq ] ) , ( [ j])-([h ] ) . let us consider the field @xcite @xmath519 applying @xmath520 to @xmath521 times equation ( [ 43 ] ) , and eliminating @xmath522 using ( [ 41b ] ) , we find that @xmath101 satisfies @xmath523 which is the regge - wheeler equation ( [ rwep ] ) ! we have found a scalar field @xmath101 , related to the even metric perturbation potential @xmath517 through ( [ fifromz ] ) , that satisfies the fundamental equation to which the _ odd _ lee reduces . + replacing @xmath524 with @xmath525 in ( [ zeq ] ) gives the following relation between @xmath517 and @xmath101 : @xmath526 \zeta = \left [ \frac{6m}{r } - ( \hd^c \hd_c + 2 ) \right ] ( r \phi).\ ] ] since @xmath517 ( or @xmath514 ) contains all the information on equivalence classes of @xmath324 solutions of the even lee , but does not admit a four dimensional translation , whereas @xmath101 satisfies the 4drw equation , one is tempted to treat even perturbations in terms of @xmath101 , using the relationship ( [ 50 ] ) . this possibility was disregarded in @xcite due to the fact that the operator on the left hand side in ( [ 50 ] ) has a non trivial kernel , suggesting that information is lost when switching from @xmath517 to @xmath101 . there is , however , a loophole in this argument , as we now proceed to explain : + expand @xmath101 and @xmath517 in spherical harmonics ( we choose to call @xmath527 the components of @xmath101 in ( [ fifromz ] ) since this field satisfies ( [ 4drwe ] ) , therefore the components ( [ 4drf ] ) satisfy ( [ rwe ] ) ) @xmath528 \phi^+_{(\ell , m ) } s_{(\ell , m)}\ ] ] in @xmath85 coordinates , equation ( [ 50 ] ) with the replacements ( [ shd ] ) reads @xmath529 \zeta_{(\ell , m ) } = \left [ \frac{1}{2r } + \frac{(\ell+2)(\ell-1)}{12 m } \right ] \phi^{(-)}_{(\ell , m)},\ ] ] where @xmath530 are the frequencies of the chandrasekhar algebraically special modes @xcite @xcite . the general solution of ( [ dual2 ] ) can be written as @xmath531_{r = r({r^*}')}\ ] ] where @xmath532 is the inverse of the function @xmath533 defined in ( [ rs ] ) , and @xmath245 is the radial coordinate of a point in the outer static region . the non - trivial kernel of the operator on the left of equation ( [ 50 ] ) is the reason why there is an arbitrary function of @xmath78 in the first term in ( [ z ] ) . note that @xmath534 if we apply @xmath535 to @xmath536 in ( [ gsz ] ) and use ( [ rwe ] ) we find that ( compare with equations ( [ fifromz ] ) and ( [ shd ] ) ) @xmath537 = ( w_{\ell}^2 f_{r_o } - \ddot f_{r_o } ) + q_{r_o}(t),\ ] ] where @xmath538 e^{-w_{\ell}r^*_o}\end{gathered}\ ] ] let us consider equations ( [ gsz])-([bxz = phi ] ) for different values of the cosmological constant : * @xmath6 : in the asymptotically flat case ( [ rs ] ) and ( [ rs0 ] ) in ( [ gsz ] ) gives @xmath539 for some @xmath540 . + according to theorem [ odd-0 ] , @xmath101 in ( [ 50 ] ) , being a solution of the @xmath6 ( [ 4drwe ] ) , satisfies @xmath541 on the exterior kruskal wedge , then from ( [ shd ] ) @xmath542 constant . and the for @xmath409 and all @xmath78 was first established in @xcite . ] more generally , solutions of ( [ rwe ] ) behave either as @xmath543 or @xmath544 for large @xmath40 , and the first type should be discarded to preserve asymptotic flatness ( alternatively , to assure the perturbative character of the initial datum ) . in any case , the integral in ( [ z ] ) converges if we take @xmath545 in ( [ z ] ) , @xmath546 and the second term above is bounded for fixed @xmath78 as @xmath75 . therefore , for metric perturbations that do not diverge as @xmath547 , it must be @xmath548 , otherwise the @xmath50 pieces of @xmath549 and @xmath482 would behave for large @xmath40 as @xmath550 times a rational function of @xmath40 ( see ( [ j])-([h ] ) ) . we conclude that the asymptotic condition as @xmath547 resolves the ambiguity in ( [ 50 ] ) and yields a 1 - 1 relation between the @xmath517 and @xmath101 fields : @xmath551 + had we used @xmath552 in ( [ z ] ) , the non - trivial function @xmath553 could have been obtained by requiring that ( [ z ] ) be a solution of ( [ fifromz ] ) ( or , equivalently , of equation ( [ zeq ] ) ) for @xmath554 satisfying ( [ rwe ] ) . as follows from equation ( [ bxz = phi ] ) , this implies that @xmath553 must be a solution of the ordinary differential equation resulting by setting the right hand side of this equation equal to zero . the ambiguity @xmath555 in the solution of this equation is again fixed by adjusting @xmath556 and @xmath557 such that ( [ gsz ] ) remains bounded as @xmath75 ( this gives @xmath558 when @xmath559 , in agreement with our previous paragraph ) . + back to the case @xmath559 , if we we let @xmath560 in ( [ z2 ] ) , allowing perturbations that diverge as @xmath75 , but require that @xmath561= ( { \partial}_t^2 - { \partial}_{r^*}^2 ) [ f_{\infty}(t ) \;\exp({w_{\ell}}r^ { * } ) ] = 0\ ] ] to preserve ( [ fifromz ] ) , we obtain @xmath562 and , from ( [ prez ] ) , the following solutions to the zerilli equation @xmath563 the relevance of ( [ ass ] ) ( equivalently , the solutions @xmath564 of ( [ zeq ] ) ) comes from the fact that these are solutions of the zerilli equation ( respectively ( [ zeq ] ) ) for _ any _ @xmath0 ( assuming the appropriate @xmath533 satisfying ( [ rs ] ) is used ) and , although useless when @xmath112 for their behavior for large @xmath232 , they are valid for @xmath222 since @xmath303 in this case , and show that there are unstable solutions in the asymptotically ads case . this is discussed in detail in section [ ins - neg - lam ] . * @xmath221 : in this case @xmath565 in ( [ gsz ] ) . according to theorem [ odd+ ] , since @xmath101 in ( [ 50 ] ) is a solution of the @xmath224 ( [ 4drwe ] ) , the @xmath554 in ( [ dual2 ] ) are bounded for @xmath566 ( @xmath287 ) . this implies that we can take @xmath567 ( @xmath568 ) in ( [ gsz ] ) , and the resulting term involving the integral will be bounded for fixed @xmath78 as @xmath405 . therefore , as in the previous case , we conclude that for metric perturbations that do not diverge as @xmath569 , the only consistent choice is @xmath570 . otherwise the @xmath50 pieces of @xmath549 and @xmath482 would diverge as @xmath571 as @xmath405 . once again , the asymptotic condition resolves the ambiguity in ( [ 50 ] ) and yields a 1 - 1 relation between the @xmath517 and @xmath101 fields : @xmath572_{r = r({r^*}')}\ ] ] * @xmath222 : for asymptotically ads black holes , we can not use the argument above , since we have proven no analogue of theorems [ odd-0 ] and [ odd+ ] in this case . this is connected to the fact that there are different consistent choices for the behavior of the @xmath554 as @xmath75 ( @xmath573 ) , and they lead to different dynamics @xcite . as an example , a boundary condition consistent with ( [ ass ] ) gives a dynamics under which the asymptotically ads schwarzschild black hole is unstable . the possibility of replacing the zerilli equation ( [ zerilli ] ) for the regge - wheeler equation ( [ rw3 ] ) depends on the choice of boundary conditions at @xmath304 . this is further investigated in section [ chd ] and in @xcite . we summarize below the results of this section : [ evensol ] consider the even sector of the lee around a schwarzschild-(a)ds background : * the solution of the @xmath58 piece of the metric perturbation in a particular gauge is given by equations ( [ pert+t ] ) , ( [ ttos ] ) and ( [ md ] ) . * the @xmath59 sector of the lee is trivial . * for @xmath112 , the solution of the @xmath115 sector is given in equations ( [ rwep ] ) , ( [ shd ] ) , ( [ z3])/([z+ ] ) and ( [ j])-([h ] ) . * for @xmath112 there is a bijection between the space @xmath574 of smooth odd solutions of the lee mod gauge transformations , and the set @xmath575 * for @xmath112 there is a bijection between @xmath574 and the set @xmath576 we gather lemma [ oddsol].iii and lemma [ evensol].iv in [ bij ] for @xmath112 there is a bijection between the space @xmath577 of smooth solutions of the lee mod gauge transformations and the set @xmath578 the dynamical perturbations are parametrized by the two solutions @xmath579 of the 4drw equation ( [ rwep ] ) , and correspond to @xmath66 perturbations . the stationary perturbations are parametrized by the first order variation of the mass @xmath116 ( @xmath58 ) and the angular momenta components @xmath580 ( @xmath59 ) , these correspond to perturbations within the kerr/ kerr-(a)ds family . the modal approach to the linear perturbation problem is based on analyzing the evolution of isolated @xmath49 modes using the zerilli and regge - wheeler equations ( [ ze ] ) and ( [ rwe ] ) respectively . in @xmath85 coordinates , these equations are separable , there are solutions of the form @xmath581 where @xmath582 satisfies a schrdinger - like equation ( note that @xmath583 agrees with the operator @xmath439 introduced in ( [ al ] ) ) @xmath584 \psi^{\pm}_{(\ell , m ) } = { \omega}^2 \psi^{\pm}_{(\ell , m)},\ ] ] with potentials ( see ( [ rwp ] ) ( [ zp ] ) ) @xmath585 it was noticed by chandrasekhar @xcite @xcite ( see also appendix a in @xcite ) that the @xmath586 satisfy @xmath587 where , generalizing chandrasekhar s equations to @xmath588 , @xmath589 and @xmath590 are the frequencies ( [ wl ] ) . a consequence of the factorization ( [ factor ] ) is that @xmath591 similarly , solutions of the ( [ rwe ] ) and ( [ ze ] ) are exchanged by @xmath592 , e.g , @xmath593 chandrasekhar noticed the factorization ( [ factor ] ) by casting the rw and zerilli potentials in riccati form , and finding the unexpected symmetry @xmath594 . we can trace origin of this symmetry to the previous to last equation in section v of @xcite , which is equivalent to our equation ( [ 50 ] ) which , combined with ( [ prez ] ) gives the @xmath595 operator in ( [ dpm ] ) for @xmath112 , we have @xmath287 , @xmath596 as @xmath597 , and we consider @xmath598 as an operator in @xmath599 , where it is self - adjoint and positive . since the general solution of the differential equation @xmath600 is a constant times @xmath601 and the general solution of the differential equation @xmath602 is a constant times @xmath603 both @xmath604 have trivial kernel in @xmath599 . since the evolution of initial data @xmath605 in @xmath599 gives @xmath606 for all @xmath78 , we may consider , in view of ( [ dmtp ] ) ( [ dptm ] ) , replacing solutions of ( [ ze ] ) with @xmath607 times solutions of ( [ rwe ] ) . this was already shown to be possible for @xmath112 in the previous section , equations ( [ z3 ] ) and ( [ z+ ] ) . the duality involving the ( [ ze ] ) and ( [ rwe ] ) is now reconsidered from the perspective offered by the factorization ( [ factor ] ) . [ lema ] assume @xmath112 . for any solution @xmath608 of ( [ ze ] ) in @xmath599 there is a unique solution @xmath377 of ( [ rwe ] ) in @xmath599 such that @xmath609 the same statement holds switching @xmath610 and @xmath611 and ( rwe ) and ( ze ) . we will only prove the first statement , as the proof of the second is completely analogous . uniqueness follows from @xmath607 being injective . to prove existence , we use the fact , discovered by price @xcite , that for @xmath6 , @xmath608 decays as @xmath80 at large @xmath78 ( the decay is exponential in @xmath78 if @xmath224 @xcite ) the time reversal symmetry of ( [ ze ] ) indicates that this also happens for large negative @xmath78 . this implies that @xmath612 admits a fourier representation @xmath613 note that @xmath614 is also a solution of ( [ ze ] ) , therefore @xmath615 is a solution of ( [ rwe ] ) . it is easy to show that this the solution sent to @xmath616 by @xmath617 : @xmath618 for sads , @xmath619 ( equation ( [ srnl ] ) ) and , from ( [ chi+ ] ) , @xmath620 the set of square integrable functions on the half line @xmath303 . since @xmath621 , we conclude that the operator @xmath607 fails to be injective in @xmath622 . also , the potential or exponential decay of @xmath608 for large @xmath623 at fixed position , required in the proof of lemma [ lema ] ( equation ( [ fourier ] ) ) allowing to replace solutions of ( [ ze ] ) with solutions of ( [ rwe ] ) fails in this case . + in fact , using @xmath621 together with ( [ sle ] ) we get the solution ( [ ass ] ) of ( [ ze ] ) found by chandrasekhar in @xcite . the choice of a plus sign in ( [ ass ] ) gives @xmath624 which grows exponentially in time while remaining in @xmath622 for every @xmath78 , that is , is an unstable mode . in the rw gauge and using the coordinates @xmath625 in ( [ sads ] ) , the metric perturbation from ( [ um ] ) is given by a particularly simple expression ( note that this is is well behaved across the horizon ) : @xmath626.\ ] ] as shown in @xcite , generic perturbations of a schwarzschild black hole give a type i spacetime , whereas the solution ( [ um])-([unsh ] ) splits one of the repeated principal null directions while preserving the degeneracy of the other one , leaving a type ii spacetime . + as explained in section [ hyp ] , different dynamics are possible in sads depending on the boundary conditions imposed to the fields at the timelike boundary . consider the zerilli equation in the orbit space sads@xmath305 @xmath627 the operator @xmath628 with domain the compactly supported functions on the half line @xmath629 is symmetric , and it admits different self adjoint extensions within @xmath622 . heuristically , self - adjoint extensions of operators like @xmath628 , which have a potential @xmath630 that is regular at the boundary , are found by demanding that when integrating by parts the boundary terms do not spoil the transposition of the operator . as the following calculation shows , @xmath631^{r^*=0}_{r^*=-\infty } + \int_{-\infty}^0 \psi_1 ( -{\partial}_{r^*}^2 + u^+_{\ell } ) \psi_2 dr^*\\ & = \left [ ( { \partial}_{r^ * } \psi_2 ) \ ; \psi_1 - \psi_2 \ ; ( { \partial}_{r^ * } \psi_1 ) \right]^{r^*=0}_{r^*=-\infty } + ( \mathcal{h}^+_{\ell } \psi_2,\psi_1 ) , \end{split } \end{aligned}\ ] ] this will be the case if we restrict @xmath622 to the subspace @xmath632 of functions satisfying the boundary condition ( see the discussion around equation ( 168 ) in @xcite , which applies to our case ) @xmath633 @xmath634 $ ] , where @xmath635 ( to be identified ) is understood as the dirichlet boundary condition @xmath636 , @xmath637 corresponds to the neumann boundary condition ( @xmath638 ) and the remaining cases to robin boundary conditions . we will call @xmath639 the self adjoint extension of @xmath628 to the domain @xmath632 . once a self - adjoint extension @xmath640 is chosen , the dynamics is given by the curve in @xmath632 obtained by solving the equation @xcite @xmath641 with initial conditions @xmath642 and this is done by using the resolution of the identity for @xmath643 , i.e. , by expanding in generalized eigenfunctions of this operator . if @xmath644 is a negative eigenvalue of @xmath643 , it belongs to the discrete part of the spectrum and , if @xmath645 and @xmath646 are the projections of @xmath55 and @xmath647 onto the @xmath648eigenspace , the projection @xmath649 of @xmath650 in ( [ hse ] ) will be @xmath651 thus , there is an instability if the spectrum of @xmath643 contains negative eigenvalues , and whether this happens or not may depend on @xmath652 , so in general the issue of stability depends on what self adjoint extension @xmath643 ( equivalently , what boundary condition at the timelike boundary ) we choose to define the dynamics . as an example , in @xcite robin boundary conditions are enforced at a finite radius @xmath653 on the @xmath654 , as given in equations ( 2.32 ) and ( 2.42 ) . this condition assures that there is a gauge for which the induced perturbed metric at the timelike hypersurface @xmath655 vanishes . one can check from the expressions in @xcite , however , that in the @xmath656 limit ( 2.32 ) and ( 2.42 ) reduce to a the dirichlet condition @xmath657 . + for the unstable mode @xmath658 we find that it belongs to @xmath643 with @xmath659 sads is unstable under dynamics that allow this boundary condition for some @xmath50 . a systematic study of stability as a function of @xmath652 is being carried out @xcite . + note that the even / odd symmetry valid for @xmath112 ( equations ( [ dmtp])-([dptm ] ) ) and the related isospectrality of @xmath660 and @xmath583 ( equations ( [ iso1])-([iso2 ] ) ) are in general broken in sads for generic boundary conditions @xcite @xcite . + note also the similarity between sads and the negative mass schwarzschild solution , for which we may choose @xmath304 at @xmath230 and @xmath661 will grow monotonically with @xmath662 . the similarity with sads is that @xmath232 is also restricted to a half - line . this allows to consider the chandrasekhar mode ( the choice of a minus sign in ( [ ass ] ) ) @xmath663 as a possible solution of ( [ ze ] ) , as it belongs for every @xmath78 to the relevant space @xmath664 ( note that @xmath665 if @xmath666 ) . this solution grows exponentially in time , so it signals an instability . there is , however , a key difference between the timelike boundary at @xmath230 of the negative mass schwarzschild solution and the conformal timelike boundary at @xmath667 of sads , as for the former there is a unique boundary condition that makes the linear perturbation scheme self - consistent , by no worsening the degree of the pole of the unperturbed curvature scalars @xcite @xcite . the solution ( [ umnm ] ) of ( [ ze ] ) satisfies precisely this boundary condition this was used in @xcite @xcite to prove the instability of the schwarzschild naked singularity . + in this section we show that there is a gauge invariant combination @xmath4 of first order variation of the css ( [ curvaturescalars ] ) that contains all the gauge invariant information about the metric perturbation class @xmath668 $ ] . in particular , @xmath669 in the rw gauge can be obtained from @xmath4 . following @xcite , we introduce the differential curvature scalars ( [ curvaturescalars ] ) . the background value of @xmath315 in the s(a)ds geometry is @xmath670 and the background value of @xmath671 in ( [ curvaturescalars ] ) is @xmath672 it follows that the combination @xmath673 is gauge invariant since , under a gauge transformation along @xmath674 , @xmath675 a lengthy calculation with the help of symbolic manipulation programs gives @xmath4 for an arbitrary perturbation class @xmath668 $ ] using the parametrization @xmath676 in lemma [ evensol].v and schwarzschild coordinates @xmath85 : @xmath677 \phi^+_{(\ell , m ) } s_{(\ell , m)},\ ] ] where @xmath678 this generalizes the result equation ( 33 ) in @xcite to the case @xmath69 . let @xmath668 \in \mathcal { l}_+$ ] and @xmath679\right)$ ] be the field ( [ g+ ] ) for the perturbation class @xmath668 $ ] . the map @xmath668 \to g_+\left([h_{{\alpha}{\beta}}^{(+)}]\right)$ ] is invertible : it is possible to construct a representative of @xmath668 $ ] from @xmath679\right)$ ] . we will prove that the linear map @xmath668 \to g_+\left([h_{{\alpha}{\beta}}^{(+)}]\right)$ ] has trivial kernel . assume that @xmath680 and @xmath681 give the same @xmath4 , then expanding @xmath4 in spherical harmonics we find that @xmath682 and also @xmath683 \chi_{(\ell , m ) } = 0 , \;\;\;\ ; ( \chi_{(\ell , m ) } = { \phi^+_{(\ell , m)}}^{(1 ) } - { \phi^+_{(\ell , m)}}^{(2)}).\ ] ] the general solution of equation ( [ psi1m2 ] ) is @xmath684 since @xmath685 , it must satisfy zerilli s equation . inserting ( [ gs ] ) in ( [ ze ] ) gives @xmath686 which only admits the trivial solution @xmath687 . + to construct a representative of @xmath688 $ ] we need @xmath116 and the @xmath689 , together with equations ( [ pert+t ] ) , ( [ ttos ] ) , ( [ md ] ) , ( [ pert - rw ] ) , ( [ prez ] ) , ( [ zerilli - exp ] ) , ( [ j ] ) and ( [ h ] ) . expanding @xmath4 in spherical harmonics @xmath690 we find that @xmath691 and @xmath689 is the only solution of @xmath692 \phi^+_{(\ell , m ) } = \frac{2r^4}{m } \frac{(\ell-2)!}{(\ell+2 ) ! } g_+^{(\ell , m)}\ ] ] that satisfies ( [ ze ] ) . in this section we establish the pointwise boundedness of @xmath4 , equation ( [ g+ ] ) , on region ii of a schwarschild or sds black hole . for @xmath236 and certain boundary conditions at the timelike boundary , this fails to be true . as an example , for boundary conditions allowing the unstable mode ( [ um ] ) , @xmath4 contains a contribution proportional to @xmath693 \right ) = g^{+ \;unst}_{(\ell , m ) } = \frac{m}{2r^4 } \frac{(\ell+2)!}{(\ell-2 ) ! } \left ( \frac{\ell(\ell+1)}{12 m } - \frac{1}{2r } \right ) \exp({w_{\ell } v } ) \ ; s_{(\ell , m)}.\ ] ] where @xmath694 is given in ( [ unsh ] ) . + back to the @xmath112 case , we know from lemma [ lema ] that for a given a solution @xmath689 of the ( [ ze ] ) , there exists a solution @xmath108 of the ( [ rwe ] ) such that @xmath695 . using this replacement in ( [ g+ ] ) gives @xmath696 \phi^+_{(\ell , m ) } = \left [ f { \partial}_r + z_{\ell } \right ] \left [ f { \partial}_r + w_{\ell } \right ] \phi^-_{(\ell , m)}\\ = { \partial}_{r^*}^2 \phi^-_{(\ell , m ) } + ( { \partial}_{r^ * } w_{\ell } + z_{\ell } w_{\ell } ) \phi^-_{(\ell , m ) } + ( w_{\ell } + z_{\ell } ) { \partial}_{r^ * } \phi^-_{(\ell , m)}\\ = { \partial}_{t}^2 \phi^-_{(\ell , m ) } + ( f v^{rw}_{\ell } + { \partial}_{r^ * } w_{\ell } + z_{\ell } w_{\ell } ) \phi^-_{(\ell , m ) } + ( w_{\ell } + z_{\ell } ) { \partial}_{r^ * } \phi^-_{(\ell , m)}.\end{gathered}\ ] ] since @xmath697 and @xmath698 we can re write ( [ g+ ] ) as @xmath699 + \frac{m}{2 r^3 } { \partial}_{r^ * } \phi_6 + \frac{m(r-3m)}{2 r^5 } { \partial}_{r^ * } \phi_5,\ ] ] where @xmath700 are all solutions of ( [ 4drwe ] ) , and therefore so is @xmath701 . note that the expression ( [ g++ ] ) for @xmath4 , written entirely in terms of solutions of ( [ 4drwe ] ) is possible thanks to the cancellation in ( [ cancel ] ) of the @xmath702 denominators in @xmath703 and @xmath704 . [ even ] * for any smooth solution of the even lee which has compact support on cauchy surfaces of the kruskal extension @xmath406 of the schwarzschild space - time , there exists a constant @xmath705 such that @xmath706 for @xmath409 . * for any mooth solution of the even lee which has compact support on cauchy surfaces of region @xmath406 of the extended sds black hole , there exists a constant @xmath705 such that @xmath707 ( equivalently @xmath708 some constant ) for @xmath251 . we treat simultaneously the @xmath6 and @xmath224 cases . for even solutions of the lee with compact support on cauchy surfaces of the kruskal extension , there is an open neighbourhood @xmath709 of @xmath710 where @xmath711 . this set is of the form @xmath712 where , for large @xmath78 , @xmath713 constant , and there is a similar open neighbourhood @xmath714 near the @xmath715 boundary of the isometric region ii@xmath716 . + in ( [ replacement ] ) , we replaced the @xmath608 fields with @xmath377 fields according to ( [ zfrw ] ) . using @xmath717 , equations ( [ dpm])-([dpm2 ] ) , ( [ factor ] ) and ( [ chim ] ) , and the fact that @xmath377 satisfies ( [ rwe ] ) , we find that , in @xmath709 , @xmath718.\ ] ] according to theorems [ odd-0 ] and [ odd+ ] , solutions @xmath101 of the 4drwe with compact support on cauchy slices of the kruskal extension satisfy @xmath719 in region ii . the 4drw fields @xmath720 in equation ( [ g++ ] ) do not have compact support on cauchy slices , their spherical harmonic components have the exponential tails ( [ 2 ] ) . in what follows we prove that the results in theorems [ odd-0 ] and [ odd+ ] hold also in this case . this will allow us to place a pointwise bound to the term between square brackets in @xmath4 , equation ( [ g++ ] ) . + let @xmath101 be any of the @xmath720 , and write @xmath101 as a sum of three solutions of the 4drwe , @xmath721 , where @xmath722 has compact support on cauchy slices of the kruskal extension and @xmath723 for @xmath724 for some positive @xmath725 , @xmath726 is supported in @xmath727 and @xmath728 is similarly supported near the @xmath715 boundary of region ii@xmath716 ( this is done by writing the @xmath101 datum on a @xmath78 slice as a sum of three appropriate terms and letting them evolve ) . in region ii , @xmath729 and @xmath730 since its satisfies the hypothesis in theorem [ odd-0 ] ( [ odd+ ] ) . on the other hand , @xmath726 decays as in ( [ 2 ] ) . since this field is bounded away the bifurcation sphere , we can adapt the proof of boundedness in the appendix in @xcite . this proof follows two steps : i ) the use of the sobolev - type inequality @xmath731 where the norm @xmath732 and ii ) the replacement of each of the terms on the right hand side of ( [ sobo ] ) with @xmath733independent quantities , which gives @xmath734constant@xmath735 . since equation ( [ sobo ] ) holds for finite norm fields , we only need to prove that step ii ) is feasible for @xmath726 . we will prove this avoiding the use of the operators @xmath736 and @xmath737 ) introduced in @xcite , applying instead the equivalent time integral technique introduced in sections 3.4 and 3.5 of @xcite for the similar problem of proving the pointwise boundedness of @xmath738 on the static region of an extreme reissner - nordstrm black hole , @xmath738 a solution of the klein - gordon equation ( note that @xmath739 is used in @xcite for the tortoise coordinate @xmath232 ) . the idea is the following : for solutions @xmath360 of the 4drwe with finite norm there is a conserved ( i.e. , time independent ) energy given by @xmath740 = \langle { \partial}_t \phi | { \partial}_t \phi \rangle + \langle \phi | r^{-1 } \mathcal{a}^{\lambda } ( r \phi ) \rangle.\ ] ] this is easily checked using the form ( [ 2 + 2 ] ) of the 4drwe . note that both terms contributing to @xmath741 $ ] are positive for a finite norm @xmath360 , since @xmath742 as a consequence of ( [ rhrc ] ) and ( [ v12a ] ) and @xmath743 . now assume there is a finite energy time integral @xmath744 of @xmath101 , that is , @xmath744 satisfies the 4drwe and @xmath745 . then @xmath746 also satisfies the 4drwe and @xmath747 ) with a time independent constant , and get the desired bound @xmath748 . note that ( [ i1 ] ) and ( [ i3 ] ) follow straightforwardly from the definition ( [ energy ] ) and the comments below it , whereas ( [ i2 ] ) follows from @xmath749 \geq ||{\partial}_t^2 \phi ||^2 = || r^{-1 } \mathcal{a}^{\lambda } ( r \phi ) ||^2 > || r^{-1 } { \partial}_{r^*}^2 ( r\phi ) ||^2 $ ] . the existence of time integrals @xmath750 of @xmath722 and @xmath751 of @xmath726 can be proved following the steps in section 3.4 of @xcite , since these fields belong to the hilbert space @xmath752 introduced in lemma 2 of this reference ( with the appropriate replacements of @xmath425 and @xmath426 ) . to prove that @xmath750 has finite energy we proceed as in lemma 3 in @xcite , since @xmath722 supported away of @xmath710 . to prove that @xmath751 has finite energy , we use ( [ 2 ] ) to show that , in @xmath709 , @xmath753 + \psi^{-,o}_{(\ell , m)}(r)\ ] ] where @xmath754 is a zero mode ( @xmath755 ) solution of equation ( [ sle ] ) , that is @xmath756 ( @xmath757 ) . the asymptotic form for large @xmath232 for a zero mode is @xmath758 + b_{(\ell , m ) } [ { r^*}^{\ell+1}+ ... ] & , \lambda=0 \\ a_{(\ell , m ) } [ e^{-\alpha r^ * } + ... ] + b_{(\ell , m ) } [ 1 + ... ] & , \lambda > 0 , \end{cases}\ ] ] where @xmath759 is defined by equation ( [ rs+l ] ) together with @xmath760 . for the unique time integral in @xmath752 of lemma 2 in @xcite it must be @xmath761 in ( [ 23 ] ) . this implies that the energy integrals ( [ i1 ] ) and ( [ i3 ] ) converge for @xmath762 . we conclude that @xmath763 and that the sum of terms within square brackets in ( [ g++ ] ) is bounded by @xmath764 for some positive @xmath765 . + to deal with the last two terms in ( [ g++ ] ) we need to prove the pointwise boundedness of @xmath766 in region ii for @xmath101 a solution of the 4drw , @xmath767 as above . we do so by adapting the proof in section 3.6 in @xcite of the pointwise boundedness of @xmath768 . for @xmath769 or @xmath770 start from the sobolev inequality ( [ sobo ] ) with @xmath101 replaced with @xmath771 : @xmath772 the square of the first term on the right hand side is bounded by the time independent energy of @xmath101 : @xmath773 & = \langle { \partial}_t \phi | { \partial}_t \phi \rangle + \langle \phi | r^{-1 } \mathcal{a}^{\lambda } ( r \phi ) \rangle \\ \nonumber & \geq \langle \phi | r^{-1 } \mathcal{a}^{\lambda } ( r \phi ) \rangle \\ \nonumber & \geq \langle \phi | -r^{-1 } { \partial}_{r^*}^2 ( r \phi ) \rangle \\ & = || r^{-1}{\partial}_{r^*}(r \phi)||^2 . \end{aligned}\ ] ] the second inequality above follows from @xmath774 being positive definite on fields in @xmath186 , the integration by parts in the last line is trivial for the compactly supported @xmath722 and , in view of ( [ 22])-([23 ] ) , holds for @xmath726 . the third term in ( [ sobotrol ] ) is similarly bounded by @xmath775 $ ] . to treat the second term on the right hand side of ( [ sobotrol ] ) we proceed as in @xcite , by taking the @xmath232 derivative of @xmath776 ( see ( [ al ] ) ) @xmath777 and using the facts that @xmath778 is also a solution of the 4drwe and that the @xmath779 s and their @xmath232 derivatives are bounded in region ii : @xmath780 , @xmath781 : @xmath782 } + \sqrt{\mathcal{e}[\tilde \phi ] } \ ; v_{1,r^*}^{max } + v_1^{max } \sqrt{\mathcal{e}[\phi ] } + v_{2,r^*}^{max } \sqrt{\mathcal{e}[r^{-1 } \mathbf{j}^2 ( r \tilde \phi ) ] } + v_{2}^{max } \sqrt{\mathcal{e}[r^{-1 } \mathbf{j}^2 ( r\phi ) ] } \end{gathered}\ ] ] the finiteness of the energy integrals above for @xmath770 can easily be checked . we conclude that there is a constant @xmath783 such that , in region ii , @xmath784 and , since @xmath243 and @xmath101 are bounded in this region , @xmath785 for some constant @xmath786 . thus , every term in ( [ g++ ] ) is bounded by a constant times @xmath787 . the large @xmath78 decay of @xmath654 @xcite , together with equations @xmath788 and @xmath789 \phi^+_{(\ell , m ) } s_{(\ell , m)},\ ] ] indicate that , at large @xmath78 , @xmath790 which , in view of the bijection ( [ i m ] ) , corresponds to a linearized kerr ( kerr de sitter ) black hole around the schwarzschild ( sds ) background . the picture that emerges from these considerations is that , for a generic perturbation , the black hole ends up settling into a slowly rotating kerr ( kerr ds ) black hole . to make statements like these more precise , all we need is quantitative information on the decay of solutions of the 4drw equation . this is so because @xmath791 _ is _ a solution of this equation , and @xmath4 can be written entirely in terms of solutions of the 4drw equation ( see equation ( [ g++ ] ) ) . alternatively , in view of theorem [ bij ] , there is a bijection between solutions of the lee and a set containing the constants @xmath792 and two fields @xmath579 that obey the 4drw equation . the perturbed metric is linearized kerr ( kerr de sitter ) if @xmath793 , which is the limit approached at large @xmath78 . quantitative results for the decay in time of solutions of the 4drw equation can be found in @xcite , @xcite and more recently in @xcite ( in this last reference , as statements on a symmetric tensor field made out of two scalar fields obeying ( [ 4drwe ] ) ) . + a natural question that arises from our results is : can we forget altogether metric perturbations and restrict ourselves to the study of the 4drw equation ? the answer to this question is in the affirmative ( theorem [ bij ] and equations ( [ qdt ] ) and ( [ g++ ] ) ) , although some technical issues should be mentioned if one intends to study perturbations using only the @xmath1 or similar perturbed curvature fields . one is related to the possibility of evolving perturbations from initial @xmath1 data . since @xmath791 obeys the 4drw equation , initial data ( e.g. , @xmath794 and @xmath5 restricted to a @xmath795constant hypersurface ) gives @xmath5 and , by expanding in spherical harmonics , the metric perturbation in the rw gauge uniquely related to it . this does not happen , however , with @xmath4 in the even sector . since the operator @xmath796 in ( [ g+ ] ) has a non trivial kernel , and @xmath4 does not satisfy a wave equation ( which would allow us to recover the lost information by proceeding as in section [ chd ] ) , the set of @xmath797 and @xmath689 at @xmath798 can not be obtained from @xmath799 and @xmath4 at @xmath798 . the reason why @xmath4 does not obey a wave equation is , of course , that is made out of the perturbation of curvature scalars involving both the riemann tensor _ and its covariant derivative _ ; the possibility of constructing a gauge invariant curvature scalar field for the even sector that does not use derivatives of the riemann tensor was ruled out in @xcite . + we should mention , however , two alternatives to the use of @xmath4 ( or similar fields involving css ) . one is using the potentials @xmath579 in theorem [ bij ] : perturbations are entirely characterized by @xmath792 ( stationary perturbations ) and the fields @xmath579 obeying the 4drw equation ( dynamical perturbations ) . this shows that we can do without the zerilli equation and that the lee does reduce to the 4drw equation . the other possibility to avoid scalar fields involving higher metric derivatives ( such as @xmath800 in @xmath4 , equation ( [ gp ] ) ) , is constructing gauge invariant combinations made out of perturbed curvature scalars _ and _ the metric perturbation . we close this section by exhibiting an example of such a construction : if we calculate the ( gauge dependent ) scalar field @xmath801 ( see ( [ curvaturescalars ] ) ) in the rw gauge , we find that @xmath802 thus @xmath803 also satisfies the 4drw equation ! we might think of using @xmath801 to measure the strength of even perturbations , but this field is gauge dependent due to the fact that @xmath804 for the background schwarzschild or s(a)ds black hole . under the gauge transformation ( [ gt ] ) , @xmath805 this suggests searching for a gauge invariant field @xmath806 that agrees with @xmath801 in the rw gauge . if we compare ( [ qp1 ] ) with equation ( [ gauge+ ] ) , we find the following solution : @xmath807 since this gauge invariant field _ reduces in the rw gauge to _ @xmath808 , and the @xmath689 are gauge invariant , @xmath809 note that the dynamical @xmath66 piece of @xmath810 satisfies the 4drw equation , which gives @xmath806 an advantage over @xmath4 : it is possible to obtain @xmath806 from the initial datum @xmath811 . once this is done , the corresponding metric perturbation in the rw gauge can be obtained by expanding @xmath806 in spherical harmonics , which gives us @xmath116 and the @xmath812 and then applying lemma [ lema ] to recover the zerilli fields @xmath689 . although the @xmath806 looks more geometrical than the potentials @xmath579 in theorem [ bij ] , we have not found an obvious interpretation for this field . i thank sergio dain for suggesting writing a detailed version of the proof of nonmodal linear stability in @xcite , andrs anabaln for suggesting considering extending this proof to the case of nonzero cosmological constant , gustav holzegel for pointing out an error in the proof of theorem [ even ] in a previous version of this manuscript and reinaldo gleiser and martin reiris for useful discussions . this work was partially funded by grants pip 11220080102479 ( conicet - argentina ) and secyt - unc 05/b498 ( universidad nacional de crdoba ) . 99 p. blue and a. soffer , `` the wave equation on the schwarzschild metric . 2 . local decay for the spin 2 regge - wheeler equation , '' j. math . phys . * 46 * , 012502 ( 2005 ) doi:10.1063/1.1824211 [ gr - qc/0310066 ] . l. t. buchman and o. c. a. sarbach , `` improved 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the nonmodal linear stability of the schwarzschild black hole established in phys . rev . lett . * 112 * ( 2014 ) 191101 is generalized to the case of a nonnegative cosmological constant @xmath0 . two gauge invariant combinations @xmath1 of perturbed scalars made out of the weyl tensor and its first covariant derivative are found such that the map @xmath2 \to \left ( g_- \left([h_{\alpha \beta } ] \right ) , g_+ \left([h_{\alpha \beta } ] \right ) \right)$ ] with domain the set of equivalent classes @xmath2 $ ] under gauge transformations of solutions of the linearized einstein s equation , is invertible . the way to reconstruct a representative of @xmath2 $ ] in terms of @xmath3 is given . it is proved that , for an arbitrary perturbation consistent with the background asymptote , @xmath4 and @xmath5 are bounded in the the outer static region . at large times , the perturbation decays leaving a linearized kerr black hole around the schwarzschild or schwarschild de sitter background solution . for negative cosmological constant it is shown that there are choices of boundary conditions at the time - like boundary under which the schwarzschild anti de sitter black hole is unstable . the root of chandrasekhar s duality relating odd and even modes is exhibited , and some technicalities related to this duality and omitted in the original proof of the @xmath6 case are explained in detail .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Early Pell Promise Act''. SEC. 2. EARLY FEDERAL PELL GRANT COMMITMENT PROGRAM. Subpart 1 of part A of title IV of the Higher Education Act of 1965 (20 U.S.C. 1070a et seq.) is amended by adding at the end the following: ``SEC. 401B. EARLY FEDERAL PELL GRANT COMMITMENT PROGRAM. ``(a) Program Authority.--The Secretary is authorized to carry out an Early Federal Pell Grant Commitment Program (referred to in this section as the `Program') under which the Secretary shall-- ``(1) award grants to State educational agencies to pay the administrative expenses incurred in participating in the Program; and ``(2) make a commitment to award Federal Pell Grants to eligible students in accordance with this section. ``(b) Program Requirements.--The Program shall meet the following requirements: ``(1) Eligible students.-- ``(A) In general.--A student shall be eligible to receive a commitment from the Secretary to receive a Federal Pell Grant early in the student's academic career if the student-- ``(i) is in 8th grade; and ``(ii) is eligible for a free or reduced price lunch under the Richard B. Russell National School Lunch Act (42 U.S.C. 1751 et seq.). ``(2) Federal pell grant commitment.-- ``(A) In general.--Except as provided in subparagraph (B), each eligible student who participates in the Program shall receive a commitment from the Secretary to receive a Federal Pell Grant during the first 2 academic years that the student is in attendance at an institution of higher education as an undergraduate student, if the student-- ``(i) applies for Federal financial aid (via the FAFSA) during the student's senior year of secondary school and during the succeeding academic year; and ``(ii) enrolls at such institution of higher education-- ``(I) not later than 3 years after such student receives a secondary school diploma or its recognized equivalent; or ``(II) if such student becomes a member of the Armed Forces (including the National Guard or Reserves), not later than 3 years after such student is discharged, separated, or released from the Armed Forces (including the National Guard or Reserves). ``(B) Exception to commitment.--If an eligible student receives a commitment from the Secretary to receive a Federal Pell Grant during the first 2 academic years that the student is in attendance at an institution of higher education as an undergraduate student and the student applies for Federal financial aid (via the FAFSA) during the student's senior year of secondary school or during the succeeding academic year, and the expected family contribution of the student for either of such years is more than 2 times the threshold amount for Federal Pell Grant eligibility for such year, then such student shall not receive a Federal Pell Grant under this section for the succeeding academic year. Such student shall continue to be eligible for any other Federal student financial aid for which the student is otherwise eligible. ``(3) Applicability of federal pell grant requirements.-- The requirements of section 401 shall apply to Federal Pell Grants awarded pursuant to this section, except that with respect to each eligible student who participates in the Program and is not subject the exception under paragraph (2)(B), the amount of each such eligible student's Federal Pell Grant only shall be calculated by deeming such student to have an expected family contribution equal to zero. ``(c) State Educational Agency Applications.-- ``(1) In general.--Each State educational agency desiring to participate in the Program shall submit an application to the Secretary at such time and in such manner as the Secretary may require. ``(2) Contents.--Each application shall include-- ``(A) a description of the proposed targeted information campaign for the Program and a copy of the plan described in subsection (e)(2); ``(B) an assurance that the State educational agency will fully cooperate with the ongoing evaluation of the Program; and ``(C) such other information as the Secretary may require. ``(d) Evaluation.-- ``(1) In general.--From amounts appropriated under subsection (f) for a fiscal year, the Secretary shall reserve not more than $1,000,000 to award a grant or contract to an organization outside the Department for an independent evaluation of the impact of the Program. ``(2) Competitive basis.--The grant or contract shall be awarded on a competitive basis. ``(3) Matters evaluated.--The evaluation described in this subsection shall consider metrics established by the Secretary that emphasize college access and success, encouraging low- income students to pursue higher education, and the cost effectiveness of the program. ``(4) Dissemination.--The findings of the evaluation shall be widely disseminated to the public by the organization conducting the evaluation as well as by the Secretary. ``(e) Targeted Information Campaign.-- ``(1) In general.--Each State educational agency receiving a grant under this section shall, in cooperation with the participating local educational agencies within the State and the Secretary, develop a targeted information campaign for the Program. ``(2) Plan.--Each State educational agency receiving a grant under this section shall include in the application submitted under subsection (c) a written plan for their proposed targeted information campaign. The plan shall include the following: ``(A) Outreach.--Outreach to students and their families, at a minimum, at the beginning and end of each academic year. ``(B) Distribution.--How the State educational agency plans to provide the outreach described in subparagraph (A) and to provide the information described in subparagraph (C). ``(C) Information.--The annual provision by the State educational agency to all students and families participating in the Program of information regarding-- ``(i) the estimated statewide average higher education institution cost data for each academic year, which cost data shall be disaggregated by-- ``(I) type of institution, including-- ``(aa) 2-year public colleges; ``(bb) 4-year public colleges; ``(cc) 4-year private colleges; and ``(dd) private, for-profit colleges; and ``(II) component, including-- ``(aa) tuition and fees; and ``(bb) room and board; ``(ii) Federal Pell Grants, including-- ``(I) the maximum Federal Pell Grant for each academic year; ``(II) when and how to apply for a Federal Pell Grant; and ``(III) what the application process for a Federal Pell Grant requires; ``(iii) State-specific college savings programs; ``(iv) State-based financial aid, including State-based merit aid; and ``(v) Federal financial aid available to students, including eligibility criteria for the Federal financial aid and an explanation of the Federal financial aid programs. ``(3) Annual information.--The information described in paragraph (2)(C) shall be provided to eligible students annually for the duration of the students' participation in the Program. ``(4) Reservation.--Each State educational agency receiving a grant under this section shall reserve $200,000 of the grant funds received each fiscal year to carry out the targeted information campaign described in this subsection. ``(f) Authorization of Appropriations.--There are authorized to be appropriated to carry out this section such sums as may be necessary.''.

Early Pell Promise Act This bill amends the Higher Education Act of 1965 to authorize the Department of Education to carry out a program of grants to state educational agencies under which a student who is in eighth grade and is eligible for a free or reduced price lunch under the Richard B. Russell National School Lunch Act may be provided a commitment to receive a Federal Pell Grant early in the student's academic career. Pursuant to such a commitment, the student shall receive a Pell Grant during the first two years of attendance at an institution of higher education (IHE) as an undergraduate if the student: files the FAFSA form during the senior year of secondary school and the succeeding year, and enrolls at the IHE not later than three years after receiving a secondary school diploma or after release from the Armed Forces. A student may not receive the early Pell Grant for a succeeding year if the expected family contribution for either year is more than twice the threshold amount for Pell Grant eligibility for that year.

in addition to its widespread role in human physiology , oestrogen ( e2 ) is implicated in the development and progression of proliferative disorders such as breast cancer ( deroo & korach , 2006 ) . e2 exerts its effects through the e2 receptors ( ers ) er and er. er is a member of the class i nuclear hormone receptor superfamily . on ligand binding , the receptor forms homodimers that bind e2-responsive elements ( eres ) located in the regulatory region of target genes ( martinez & wahli , 1989 ) . although the effects of e2 on the proliferation of human breast cancer cells have been known for many years , only recently have gene expression profiling studies suggested a role of the hormone in dna repair ( gadal et al , 2005 ) . dna - dependent protein kinase ( dna - pk ) is a serine / threonine protein kinase comprising a catalytic subunit ( dna - pkcs ) and ku subunits , which act as regulatory elements ( collis et al , 2005 ) . dna - pk is the main component of the non - homologous end - joining pathway of dna double - strand break ( dsb ) repair in mammalian cells ( lees - miller , 1996 ) . it has been proposed that dna - pk is a molecular sensor of dna damage , which enhances dsb repair through the phosphorylation of many downstream targets ( anderson & lees - miller , 1992 ; kysela et al , 2005 ; hah et al , 2007 ) . the crucial role of dna - pk is to repair dsbs that either arise endogenously during normal cellular processes or are exogenously caused by genotoxic agents such as ionizing radiation ( ir ) . unrepaired dsbs are known to trigger cell - cycle checkpoint arrest and cell death ( norbury & hickson , 2001 ) . recently , we demonstrated that glycogen synthase kinase 3 stabilizes er and modulates its transcriptional activity ( medunjanin et al , 2005 ) . in addition , co - immunoprecipitation studies revealed the involvement of a 70 kd protein that was subsequently identified as ku70 , a component of the dna - pk holoenzyme . when studying the role of dna - pk in er activity , increased dna - pkcs expression levels were observed in cells treated with e2 . to test our hypothesis , cells from the breast cancer cell line meln were treated with e2 in a time - dependent manner , which resulted in a marked upregulation of dna - pkcs and an expected downregulation of er within 6 h ( fig 1a ) . quantitative real - time reverse transcriptase pcr revealed that e2 induced a significant about twofold induction of dna - pkcs messenger rna expression that peaked at 1 h ( fig 1b ) . this was confirmed by transfection of erflag fusion protein into er-negative cos-7 cells yielding upregulation of dna - pkcs after e2 treatment only in er-positive cells ( fig 1c ) . e2-dependent induction of dna - pkcs was reduced markedly with either the specific er antagonist ici 182,780 ( fig 1d ) or the transcriptional repressor actinomycin d ( actd ; fig 1e ) . furthermore , we used small interfering rna ( sirna ) to knockdown er levels . in the presence of the specific sirna , the 13 bp palindromic ere with the consensus sequence 5-ggtcannntgacc-3 is well known ( klein - hitpass et al , 1988 ) . however , it has been shown that imperfect ' palindromic eres might also act synergistically to permit translational activity ( martinez & wahli , 1989 ) . analysis of the dna - pkcs promoter demonstrated ere - binding elements located in close proximity to each other : an imperfect ' palindromic ere at position 184 and a half palindromic ere at position 274 ( fig 2a ) . first , we cloned a previously described fragment of the dna - pkcs promoter ( from 3 to 606 ; connelly et al , 1998 ) into the pgl3-basic luciferase reporter plasmid and tested for promoter activity 72 h after transient transfection of human hela and mcf-7 cells . as hela cells lack a detectable endogenous er , er was co - transfected with the dna - pkcs reporter gene . co - transfection induced a threefold increase in luciferase activity that increased further on e2 treatment ( fig 2b ) . transfection of the dna - pkcs reporter into the er-positive cell line mcf-7 was also accompanied by a strong luciferase signal that was sensitive to e2 stimulation . according to the above promoter analysis , the promoter region of dna - pkcs was subsequently restricted to position 220 upstream from the dna - pkcs initiation site , cloned into the luciferase reporter plasmid and examined for promoter activity 72 h after e2 stimulation , confirming the relevance of the hypothesized eres in dna - pkcs transactivation . e2-induced increase in luciferase activity was reduced when the cells had been preincubated with the anti - e2 ici 182,780 before stimulation ( fig 2c ) . binding of er to the dna - pkcs promoter was further confirmed by chromatin immunoprecipitation assays with er antibody . in meln cells , occupancy of the dna - pkcs promoter by er was not detected in the absence of e2 , but increased markedly on e2 stimulation ( fig 2d , upper panel ) . in subsequent experiments , we amplified a portion of human dna - pkcs promoter bearing a putative half or imperfect ere . the er binding to these sites was reduced markedly after e2 treatment ( fig 2d ) . immunoprecipitations performed with either immunoglobulin g ( igg ) or a control region ( from 4,014 to 3,717 ) of the dna - pkcs promoter upstream from the ere were used as controls . together , these findings indicate that : ( i ) er directly binds to the dna - pkcs promoter and ( ii ) e2 stimulation is associated with increased occupancy of eres by er. increased expression of dna - pkcs alone might provide important protection from genotoxic stress , even in cells already containing functional dna - pk ( shen et al , 1998 ) . to determine the functional significance of our finding , we examined the effect of e2 on dna dsb repair in human meln cells by studying the kinetics of -h2ax foci formation , which result from dsbs during irradiation ( sedelnikova et al , 2002 ; rothkamm & lobrich , 2003 ) . time course experiments revealed that the number of -h2ax foci reached its maximum 1 h after irradiation of meln cells . after irradiation , it fell almost to control level within 6 h ( fig 3a ) . foci formation was reduced significantly when cells were exposed to e2 before irradiation ( fig 3a ) . as foci formation takes a finite amount of time , this assay was not able to assess the initial number of dsbs . thus , dsb induction and repair after ir was additionally visualized and quantified by using the neutral comet assay . pretreatment of meln cells with e2 significantly increased the repair of damaged dna that is , decreased the comet tail moment western blot analyses visualized reduced phosphorylation of -h2ax in e2-treated cells compared with untreated cells and confirmed the results of the immunofluorescence microscopy ( fig 3c ) . a previous study ( li & stern , 2005 ) indicated that phosphorylation of dna repair protein checkpoint kinase 2 ( chk2 ) at thr 68 depends on the activation of dna - pk after irradiation . therefore , phosphorylation of chk2 at thr 68 was used to show that dna - pk had indeed been activated . by contrast , phosphorylation of ataxia teleangiectasia mutated ( atm ) , another central kinase of dsb repair , was not sensitive to e2 treatment ( fig 3c ) . when dna - pk had been inhibited , e2 lost its preventive effect on -h2ax foci formation after ir ( fig 3d ) . involvement of er in dsb repair was further supported by using the specific er antagonist ici 182,780 . e2-dependent induction of dna - pkcs was reduced markedly when meln cells were preincubated with the anti - e2 ici 182,780 before irradiation . consequently , e2-induced increased phosphorylation of chk2 at thr 68 was prevented markedly in ici - treated cells ( fig 4a ) . previous studies demonstrated that atm- and rad3-related ( atr ) , another pi3-related kinase , also regulate phosphorylation of chk2 at thr 68 ( matsuoka et al , 2000 ; wang et al , 2006 ) . to rule out atm and atr as activators of chk2 no reduction in the phosphorylation of chk2 at thr 68 after e2 treatment was observed when the atm / atr inhibitor was used ( fig 4b ) . to test our hypothesis , cells from the breast cancer cell line meln were treated with e2 in a time - dependent manner , which resulted in a marked upregulation of dna - pkcs and an expected downregulation of er within 6 h ( fig 1a ) . quantitative real - time reverse transcriptase pcr revealed that e2 induced a significant about twofold induction of dna - pkcs messenger rna expression that peaked at 1 h ( fig 1b ) . this was confirmed by transfection of erflag fusion protein into er-negative cos-7 cells yielding upregulation of dna - pkcs after e2 treatment only in er-positive cells ( fig 1c ) . e2-dependent induction of dna - pkcs was reduced markedly with either the specific er antagonist ici 182,780 ( fig 1d ) or the transcriptional repressor actinomycin d ( actd ; fig 1e ) . furthermore , we used small interfering rna ( sirna ) to knockdown er levels . in the presence of the specific sirna , the 13 bp palindromic ere with the consensus sequence 5-ggtcannntgacc-3 is well known ( klein - hitpass et al , 1988 ) . however , it has been shown that imperfect ' palindromic eres might also act synergistically to permit translational activity ( martinez & wahli , 1989 ) . analysis of the dna - pkcs promoter demonstrated ere - binding elements located in close proximity to each other : an imperfect ' palindromic ere at position 184 and a half palindromic ere at position 274 ( fig 2a ) . first , we cloned a previously described fragment of the dna - pkcs promoter ( from 3 to 606 ; connelly et al , 1998 ) into the pgl3-basic luciferase reporter plasmid and tested for promoter activity 72 h after transient transfection of human hela and mcf-7 cells . as hela cells lack a detectable endogenous er , er was co - transfected with the dna - pkcs reporter gene . co - transfection induced a threefold increase in luciferase activity that increased further on e2 treatment ( fig 2b ) . transfection of the dna - pkcs reporter into the er-positive cell line mcf-7 was also accompanied by a strong luciferase signal that was sensitive to e2 stimulation . according to the above promoter analysis , the promoter region of dna - pkcs was subsequently restricted to position 220 upstream from the dna - pkcs initiation site , cloned into the luciferase reporter plasmid and examined for promoter activity 72 h after e2 stimulation , confirming the relevance of the hypothesized eres in dna - pkcs transactivation . e2-induced increase in luciferase activity was reduced when the cells had been preincubated with the anti - e2 ici 182,780 before stimulation ( fig 2c ) . binding of er to the dna - pkcs promoter was further confirmed by chromatin immunoprecipitation assays with er antibody . in meln cells , occupancy of the dna - pkcs promoter by er was not detected in the absence of e2 , but increased markedly on e2 stimulation ( fig 2d , upper panel ) . in subsequent experiments , we amplified a portion of human dna - pkcs promoter bearing a putative half or imperfect ere . the er binding to these sites was reduced markedly after e2 treatment ( fig 2d ) . immunoprecipitations performed with either immunoglobulin g ( igg ) or a control region ( from 4,014 to 3,717 ) of the dna - pkcs promoter upstream from the ere were used as controls . together , these findings indicate that : ( i ) er directly binds to the dna - pkcs promoter and ( ii ) e2 stimulation is associated with increased occupancy of eres by er. increased expression of dna - pkcs alone might provide important protection from genotoxic stress , even in cells already containing functional dna - pk ( shen et al , 1998 ) . to determine the functional significance of our finding , we examined the effect of e2 on dna dsb repair in human meln cells by studying the kinetics of -h2ax foci formation , which result from dsbs during irradiation ( sedelnikova et al , 2002 ; rothkamm & lobrich , 2003 ) . time course experiments revealed that the number of -h2ax foci reached its maximum 1 h after irradiation of meln cells . after irradiation , it fell almost to control level within 6 h ( fig 3a ) . foci formation was reduced significantly when cells were exposed to e2 before irradiation ( fig 3a ) . as foci formation takes a finite amount of time , this assay was not able to assess the initial number of dsbs . thus , dsb induction and repair after ir was additionally visualized and quantified by using the neutral comet assay . pretreatment of meln cells with e2 significantly increased the repair of damaged dna that is , decreased the comet tail moment western blot analyses visualized reduced phosphorylation of -h2ax in e2-treated cells compared with untreated cells and confirmed the results of the immunofluorescence microscopy ( fig 3c ) . a previous study ( li & stern , 2005 ) indicated that phosphorylation of dna repair protein checkpoint kinase 2 ( chk2 ) at thr 68 depends on the activation of dna - pk after irradiation . therefore , phosphorylation of chk2 at thr 68 was used to show that dna - pk had indeed been activated . by contrast , phosphorylation of ataxia teleangiectasia mutated ( atm ) , another central kinase of dsb repair , was not sensitive to e2 treatment ( fig 3c ) . when dna - pk had been inhibited , e2 lost its preventive effect on -h2ax foci formation after ir ( fig 3d ) . involvement of er in dsb repair was further supported by using the specific er antagonist ici 182,780 . e2-dependent induction of dna - pkcs was reduced markedly when meln cells were preincubated with the anti - e2 ici 182,780 before irradiation . consequently , e2-induced increased phosphorylation of chk2 at thr 68 was prevented markedly in ici - treated cells ( fig 4a ) . previous studies demonstrated that atm- and rad3-related ( atr ) , another pi3-related kinase , also regulate phosphorylation of chk2 at thr 68 ( matsuoka et al , 2000 ; wang et al , 2006 ) . to rule out atm and atr as activators of chk2 no reduction in the phosphorylation of chk2 at thr 68 after e2 treatment was observed when the atm / atr inhibitor was used ( fig 4b ) . in recent years , mammalian dna - pkcs has been shown to be a crucial component of the signalling mechanisms of both dsb repair and v(d)j recombination ( shen et al , 1998 ) , which was further supported by the finding that a point mutation in the carboxy terminus of dna - pkcs leads to increased radiosensitivity of chinese hamster ovary cells ( errami et al , 2000 ; woods et al , 2002 ) . furthermore , severe combined immunodeficient ( scid ) mice , which lack dna - pkcs , exhibit increased susceptibility to ir and impaired v(d)j recombination ( smith & jackson , 1999 ) . this is the first report to show that dna - pk can be induced directly by e2 through increased binding of the transcription factor er to the dna - pkcs promoter . furthermore , we characterized functional eres in the dna - pkcs promoter . concerning this finding , it is interesting that the distance between the er half - sites is approximately within one nucleosome ( 200 bp ) , raising the possibility that they are in topographical proximity in the chromatin . furthermore , the resulting dna - pkcs promoter activity might be regulated tightly by a dynamic interplay between these two ere sites . a positive effect of e2 on global genomic repair of dna and survival has been shown before ( boulay & perdiz , 2005 ) . now , our data identify dna - pk as the mediator of e2-induced dsb repair . elevated levels of dna - pk warrant a quick and strong response to dna damage , resulting in reduced cellular levels of dsbs . an involvement of atm , another important dna repair enzyme , could be excluded in this context . clinically , the er has a central role in controlling cell growth in mammary tissue , and its expression level in breast cancer is associated with longer survival and a better response to therapeutic measures ( ruiz et al , 2006 ) . however , through dna - pk activation , er positivity might confer a selective advantage to tumour cells when exposed to radiotherapy or chemotherapeutic agents . indeed , breast cancer cell lines incubated with tamoxifen were shown to be more sensitive to irradiation ( wazer et al , 1989 ) , and the combination of radiotherapy and anti - hormonal therapy has been shown to prevent tumour recurrence ( fisher et al , 2002 ) . whether anti - hormonal pretreatment before radiotherapy improves treatment results in patients with breast cancer has , however , not yet been established . nonetheless , our finding of an interaction between two central components of dna replication and repair sheds further light on tumour biology and reveals new possibilities for the prevention and therapy of e2-sensitive proliferative diseases . antibodies and reagents . the following antibodies , kit and inhibitors were used : anti - cathepsin d ( 4g2 ) and anti--actin ( abcam , cambridge , uk ) ; anti - er ( mab463 ; chemicon , bad nauheim , germany ) ; anti - er ( hc-20 ) , anti - ku80 ( sc-1484 ) and anti - dna - pkcs ( sc-5282 ; santa cruz biotechnology , heidelberg , germany ) ; anti - chk2 ( # 2662 ) , anti - chk2 ( # 3440 ) and dna damage sampler kit ( # 9947 ; new england biolabs , frankfurt am main , germany ) ; alexa - green conjugated anti - mouse igg ( molecular probes , eugene , or , usa ) ; ici 182,780 , atm / atr kinase inhibitor ( cgk 733 ) , actd and dna - pk inhibitor ( nu7026 ; merck , darmstadt , germany ) . transfection of meln cells with sirna has been described before ( grisouard et al , 2007 ) . the sirna oligonucleotides with 3-tt overhangs were purchased from mwg - biotech ag ( ebersberg , germany ) . the following sirna sequences were used : ( sier ) 5-aggcucauuccagccacagttdtdt-3 ; and ( sidna - pkcs ) 5-cuuuaugguggccauggagdtdt-3. the concentration of sirnas was 20 nm during transfection . for control , we used gl3-targeted sirna . was performed according to the manufacturer 's instructions ( trevigen , gaithersburg , md , usa ) . briefly , after irradiation , cells were collected and mixed with low - melting agarose . after lysis , electrophoresis was performed at 1 v / cm and 15 ma for 40 min . slides were stained with sybr green dye ( invitrogen , karlsruhe , germany ) for 10 min . a total of 100 randomly selected cells per sample were captured under a zeiss fluorescent microscope and digital fluorescent images were obtained using the axiovision software ( carl zeiss imaging , jena , germany ) . the relative length and intensity of sybr green - stained dna tails to heads were proportional to the amount of dna damage present in the individual nucleus and was measured by olive tail moment with tritek comet score software ( tritek , sumerduck , va , usa ) . chromatin immunoprecipitation assays were performed as described previously ( wei et al , 2006 ) . briefly , lysates were sonicated with branson sonifer cell disruptor b15 ( branson , danbury , ct , usa ) to shear dna to an average size of 6001,000 bp . for chromatin immunoprecipitation , anti - er ( mab463 ) and igg ( pierce , bonn , germany ) were used . the meln cells were washed with phosphate - buffered saline ( mg and ca free ) and lysed in 150 l per well luciferase cell culture lysis reagent ( promega , mannheim , germany ) . luciferase assays were performed by using the firefly luciferase assay system from promega according to the manufacturer 's instructions and quantified with a luminometer ( lb9506 , berthold , bad wildbad , germany ) . the plasmids for er have been described previously ( medunjanin et al , 2005 ) . constructs of the dna - pkcs promoter ( genbank accession number u63630 ) were produced by pcr amplification using genomic dna from meln cells . the resulting fragments , spanning the promoter region from positions 1,026 , 606 , 220 to position 2 relative to the transcriptional start site , were cloned into the nhei and xhoi cloning sites of the pgl3-basic vector upstream from the firefly luciferase gene ( promega ) . statistical analysis .

transcriptional activation of dna - dependent protein kinase catalytic subunit gene expression by oestrogen receptor-in this report braun - dullaeus and co - workers demonstrate that dna - pk can be directly induced by oestrogen through increased binding of the transcription factor er to the dna - pkcs promoter and identify functional oestrogen responsive dna elements ( eres ) within the dna - pkcs promoter . oestrogen - induced dna - pk transactivation results in an increased ability of the cells to repair dna double - strand breaks .

To view our videos, you need to enable JavaScript. Learn how . install Adobe Flash 9 or above. Install now . Then come back here and refresh the page. Access to our video is always free for Time Warner Cable video customers who login with their TWC ID. To get you to the stories you care about, we are offering everyone 10 video views per month. Time Warner Cable video customers: Sign in with your TWC ID to access our video clips. The victim of an alleged hate crime in Union Square last week has died, and the medical examiner is ruling the death a homicide. Officials say 62-year-old Jeffery Babbit passed away on Monday from a brain hemorrhage after suffering a skull fracture. Police say Babbit was punched by 31-year-old Martin Redrick, during an attack on three people. According to officials, Redrick allegedly walked out of the Union Square subway station and began shouting racist threats before he hit Babbit and two others. Babbit went to Bellevue Hospital, where officials say he eventually slipped into a coma. His neighbors say they're in shock. "Very peaceful, very friendly, very helpful for example, like a neighbor. Very, very good people," said one neighbor. "He was really kind-hearted, and it's really unfortunate that happened," said another. "This is a crime, and I cannot tell you how I would like to get my hands on that man. God forgive me," said a third. Redrick, who also goes by the name Lashawn Martin, is being held on $1 million bail and is due back in court on Tuesday, according to police. Officials say Redrick is charged with second and third degree assault, but those charges may be upgraded. ||||| For more than a decade, Jeffrey Babbitt traveled two or three times a week from his home in Sheepshead Bay, Brooklyn, to a comic book store called Forbidden Planet just below Union Square in Manhattan. There, he bought the latest copies of “X-Men” or “Doctor Who,” or sometimes just chatted up the employees, who over the years had become good friends. For Mr. Babbitt, 62, who friends said was a retired train conductor, the store offered an escape into fantasy and a bit of a respite from home, where he cared for his 94-year-old mother, Lucille Babbitt. “He was just a really, really, really sweet guy,” said Jeff Ayers, a manager at the store who has known Mr. Babbit for years. “One of our staff just had a baby and he was dying to see pictures.” Mr. Babbitt was walking through Union Square near Forbidden Planet last Wednesday when he was punched in the face seemingly at random by an assailant who, the police said, declared his intention to “punch the first white man I see.” After he was hit, Mr. Babbitt fell to the ground, striking his head on the pavement, the police said. The attacker, whom the police identified as Lashawn Marten, then struck two men who came to Mr. Babbitt’s aid, they said. Mr. Babbitt was taken to Bellevue Hospital Center, where, the police said, he was eventually declared brain dead and died on Monday morning. In a neighborhood that had long ago moved past its rough-and-tumble days, the seemingly random act of violence at 3 p.m. in a bustling park came as a shock. The police said that Mr. Marten, 40, had a long history of arrests, some for assault and drug offenses in New York City and in Newburgh, N.Y. He was arrested shortly after the attack and charged with three counts of assault. With Mr. Babbitt’s death, those charges will most likely be upgraded by a grand jury that is to hear the case on Tuesday, according to the police. Mr. Marten, who is black, has also gone by the alias Martin Redrick and listed a different birth date, the police said. He was living in supported housing for formerly homeless people and those with psychiatric disabilities provided by the Jewish Board of Family and Children’s Services, said Shelley Ruchti, the group’s chief communications officer. She declined to describe the reason for his living there. On Monday evening, many residents at Mr. Babbitt’s modest brick apartment building on Ocean Avenue in Sheepshead Bay had something nice to say about him, and could only shake their heads at the senselessness of his death. “He was as good as good can be,” said Audrey Feifer, 75. “This should never have happened, no matter what color this person is.” Ms. Feifer said Mr. Babbitt, who she said moved to the neighborhood from Florida about 20 years ago, used to insist on giving her rides to bus stops or to buy doughnuts. Inside the apartment that Mr. Babbitt shared with his mother, Ms. Feifer said, he kept model steam locomotives, stacks of magazines about trains, and many comic books. He often wore shirts showing pictures of fairies and once drove Ms. Feifer out of state to join him at a Fairy-Con gathering, a festival for people who celebrate fairies. A sister, his only sibling, helped Mr. Babbitt care for their mother, but she died from cancer about two years ago, Ms. Feifer said, and Mr. Babbitt took over all the caretaking responsibilities. He did not seem to mind, neighbors said. “He’d say, ‘Hi, Mom!’ so loud everybody could hear it,” said Igor Sapozhnikov, 56. “He loved his mother, and his mother loved him very well.” Mr. Babbitt’s mother was at his bedside at least part of the time he was in the hospital, said Mr. Ayers, who visited him there. Many neighbors wonder who will care for her now. Mr. Babbitt’s death came as the police said they were looking for a suspect in another bizarre and possibly racially motivated attack on the M60 bus in Harlem on Friday, Aug. 30. In that unrelated attack, a man hurled a racial epithet at a 31-year-old Queens man, calling him a “cracker,” before knocking him to the ground and punching him. The victim, whose name was not released, sustained a broken nose and a fractured eye socket. The suspect, described by the police as a black man in his late 30s, fled on foot and had not been located. At Forbidden Planet, employees were left bereft by Mr. Babbitt’s death, said Mr. Ayers, who broke into tears several times during a short interview. Mr. Ayers had spoken to Mr. Babbitt the day before the attack when he came to the store looking to pick up a copy of a comic art book called “The Art of Grimm Fairy Tales” that he had ordered. The order had not yet arrived, and Mr. Babbitt was slightly annoyed, Mr. Ayers said. “He’s been hounding me for weeks and weeks for this book,” he said. Mr. Ayers said employees were also concerned about Mr. Babbitt’s mother. He said they planned to set up a fund to help continue her care. “We’re a community here,” he said. “These are people whose lives we’re tied to.”

– The death of a man who suffered a skull fracture and brain hemorrhage in Manhattan after being punched has been ruled a homicide, NY1 reports. Jeffrey Babbitt (some outlets use the spelling "Jeffery Babbit"), 62, was walking in Union Square around 3pm last Wednesday when Lashawn Marten allegedly punched him in the face in an apparently random attack, the New York Times reports. Marten, who is also reportedly known as Martin Redrick, said he wanted to "punch the first white man I see," police say. When two men came to help Babbitt, who hit his head on the pavement when he fell, Marten allegedly hit them, as well. Marten was arrested and charged with three counts of assault, but in light of Babbitt's death yesterday, those charges will probably be upgraded by a grand jury, which is hearing the case today, police say. Marten was allegedly yelling racist threats as he walked out of the subway station before the attack. Police are investigating the incident as a possible hate crime, Gothamist reports.

the use of 16s rrna massive sequencing has deeply improved the technical possibilities to describe the taxonomic composition and functionality of microbial communities 1 . following the reduction in dna sequencing cost , many studies have been performed using amplicon libraries to taxonomically describe microbial communities in many different environments . the large number of sequence reads can be taxonomically assigned by comparison with taxonomically classified sequences present in dedicated databases of 16s rrna genes , as for instance silva 2 , greengenes 3 or the ribosomal database project 4 . in particular , one of the most popular tools used to assign sequence reads to the prokaryotic taxonomy is the nave bayesian classifier tool hosted by ribosomal database project ( rdp classifier ) 4 . the rdp classifier tool uses a very fast algorithm , based on the bayes ' theorem , suitable for the analysis of large amount of sequence data . this algorithm has been tested on near - full - length 16s rrna sequences and on randomly generated 16s rrna sequence fragments of 400 , 200 , 100 and 50 bases in length from a number ( 5,014 ) of type strains belonging to 988 genera 4 . an overall accuracy of above 88.7% and 83.2% for 400 and 200 base segments , respectively ( very similar to the accuracy obtained with the near - full - length 16s rrna sequence ) was reported 4 . moreover , an average accuracy at genus level of 71.1% and 51.5% for the 100 and the 50 base segments respectively was found . however , these results have been obtained using a 16s rrna sequence fragments dataset built with sequences derived from well taxonomically defined organisms . no data have been reported on datasets composed by 16srrna sequences from particular regions of the 16s molecule ( e.g. v3 and v6 ) and obtained after amplification of dna from environmental samples . in the last years , illumina sequencing technology has emerged as one of the most popular sequencing technology , thanks to the lower prices , higher number of generated sequences and accuracy than pyrosequencing and ion torrent technologies 1 , 5 - 8 . in particular , different illumina platforms are available ( with different cost of sequencing ) which provide different number of reads and different reads lengths ( see for instance http://www.illumina.com/systems/sequencing.ilmn ) . additionally , illumina reads are usually 100 - 200 nt long ( depending on the techniques used ) and 16s rrna amplicon studies have focused on single variable regions of the 16s rrna gene , as the v3 , v4 or v6 , which are approximately 100 - 300 bp long . consequently , a concern about the amount of reads to generate and the setting of the bootstrap threshold of rdp classifier to provide biologically meaningful data is present . more specifically , there is a lack of information on the percentage of reads which can be assigned to the various phylogenetic levels with illumina 16s rrna metabarcoding . here , we report a benchmark of rdp classifier based on environmental sequence datasets obtained with illumina sequencing technology . in particular , we investigated the effect of bootstrap cutoff values on the accuracy of taxonomic attribution of illumina reads . results obtained provide a guideline for the selection of optimal bootstrap cutoff values in terms of data retention along the different taxonomic ranks . five datasets of 16s rrna gene illumina reads , generated from environmental dna , were analyzed ( table 1 ) . these datasets contains a high number of reads per sample ( from 28634 to 759518 reads per sample ) and are including reads obtained from v3 , v4 and v6 regions . reads present in the analyzed datasets were trimmed with streamingtrim version 1.0 9 , before taxonomic assignment with the rdp classifier . the proportion of assigned reads in relation to the bootstrap cutoff value ( from 0.1 to 1.0 with an increment of 0.1 ) for each taxonomic level ( from domain to genus ) is reported in figure 1 . as expected , the proportion of assigned reads decreased going down along taxonomic levels from phylum ( from a mean of 100% to a mean of 25% , in the two datasets ) to genus ( from a mean of 60% to a mean of smaller than 5% , in the two datasets ) . in particular it is worth noticing that all datasets , which included three variable regions ( v3 , v4 and v6 ) of 16s rrna gene , more than 25% of the reads could be assigned to the family level using a bootstrap cutoff value of 0.5 ( the default cut - off value reported in the rdp classifier tutorial ) . moreover , even at higher cutoff values ( > 0.8 ) an appreciable number of reads were still assigned ( 5%-10% ) . interestingly , the v3 region performed better in the taxonomic attribution at order and family levels , indicating that even highly stringent bootstrap cut - off values ( e.g. 0.7 ) may allow to assign more reads from v3 region than from v4 and v6 region , which consequently resulted less taxonomically informative . the assignments trend at the genus level ( the lower taxonomic level that can be obtained using the rdp classifier ) was then inspected ( figure 2 ) . here also , v3 region better performed than v4 and v6 region in the retention of taxonomic information lowering bootstrap values , especially at bootstrap cutoff value of 0.5 and lower . a pseudo - fit of curve was also produced ( supplementary material : figure s1 ) , which may allow researchers to infer the percentage of sequences that could be assigned to the genus level at different rdp bootstrap cut - offs . in conclusion , illumina reads , shorter than 200 nt , can be classified using one of the most common 16s rrna sequence classifier : the rdp classifier . as one would expect , the increase of the bootstrap cutoff value leads to a decreased number of assigned sequences . however , even at cutoffs higher than those indicated in the rdp classifier tutorial , approximately 20 - 30% of the analyzed reads were still assigned . these results indicate that illumina - based metabarcode sequencing of 16s rrna gene can provide reliable information for taxonomic composition of a community at the genus level even using classification software not specifically designed for this type of sequences . the reported models for trend plots can guide experimentalists in choosing the sequencing depth more adapted for retaining an appreciable number of assigned reads different taxonomic resolution .

here we report a benchmark of the effect of bootstrap cut - off values of the rdp classifier tool in terms of data retention along the different taxonomic ranks by using illumina reads . results provide guidelines for planning sequencing depths and selection of bootstrap cut - off in taxonomic assignments .

transfer rna ( trna ) genes play an essential role in protein translation in all living cells . among the numerous trna search programs created in the last 20 years , trnascan - se ( 1 ) remains a popular standard for whole - genome annotation of trna genes . the program has undergone major development in the past three years , and now implements a number of analytic improvements , including integration of the infernal covariance model search program ( 2 ) , isotype - specific scoring models and the ability to distinguish between cytosolic - type and nuclear - encoded mitochondrial - type trnas ( chan et al . , in preparation ) . to catalog the increasing number of trnas found in complete genomes , we developed the genomic trna database ( gtrnadb ) as a repository for all identifications made by trnascan - se . the initial version of the database provided a summary overview of all trnas , display of trnascan - se identification information , the primary sequences and predicted secondary structures of trnas , multi - gene alignments , and links for each trna to explore genomic context within the ucsc genome browser ( 3 ) and the archaeal / microbial genome browser ( 4 ) . in addition , the gtrnadb search module allowed search by characteristics , and a custom blast ( 5 ) server enabled study of trna gene similarity across all sequences in the gtrnadb . our understanding of the multifaceted roles of trnas has leaped forward in recent years , with new appreciation for unexpected complexity and functionality of individual trnas . unusual trnas range from a highly tissue - specific trna in mammalian brains ( 6 ) , to trnas with modifications that enable highly specific regulation of trna stability ( 7 ) , to trna furthermore , abundant small rnas derived from trnas are now known to have major roles in abnormal cell proliferation and other diseases ( 912 ) , and are likely to emerge as important players in other contexts with improved methods for their detection ( 13 ) . given this new complexity , the need to study the functional roles of individual trnas has motivated development of the new gtrnadb , which now enables the identification of unusual features within trnas , sequence polymorphisms in populations , epigenetic gene locus activation state and trna transcript abundance among different cell types . by collecting and integrating these diverse types of information in one place , we hope to accelerate the discovery of new trna biology and foster an appreciation of the unrecognized regulatory roles of trnas across all domains of life . the new gtrnadb has greatly expanded in size and phylogenetic scope , now containing more than 367 000 trnas derived from the genomes of 155 eukaryotes , 184 archaea and 4032 bacteria ( table 1 ) . this constitutes a more than 4x increase from the original description of the database ( 14 ) . because of the large increase in the number of species , a new quick search box on the home page allows users to type in any part of a species name ( e.g. dros or coli ) , and get direct access to the trna gene summary page for all matching genomes . as before , the gene summary page has summary statistics for all the trnas in a selected genome , arranged by two - box , four - box or six - box codon families for quick inspection of trna counts , intron counts and potential pseudogenes . on the left side of the trna gene summary page is a number of items to give quick access to genome - specific trna data generated by trnascan - se . a major improvement has been made to the first menu item , the trna gene list , which now includes all fully sortable columns and a search box that allows dynamic filtering for any number of trna traits ( e.g. arg tcg chr1: ) . this feature is extremely efficient for finding specific subsets within many dozens or hundreds of trnas in a given genome . sorting from highest to lowest trna genes by score , number of introns or number of canonical structure mismatches also allows ranking trnas by traits of interest ; multiple keys can be used to sort by holding down the shift key and selecting additional columns . the most significant new feature of gtrnadb is the ability to show extensive information for each trna gene on its own page ( figure 1 ) . by clicking on a trna name in the gene list , one is able to view a full page of rich new information , including a new feature of trnascan - se 2.0 ( chan et al . , in preparation ) : trna prediction based on newly built isotype - specific models . in prior versions of trnascan - se , the trna isotype was entirely determined based on the anticodon . however , classifying trnas based on the highest - scoring isotype model has been shown to be more effective in bacteria with tfam ( 15 ) . accordingly , the new individual trna information pages give trnascan - se statistics for top scoring / second best scoring isotype model , which is usually consistent with the anticodon , but sometimes is not . disagreement could be a trait of trnas no longer functional in translation , or of hybrid trnas which may cause ambiguous codon recognition ( 16 ) . the upstream and downstream sequences flanking each trna gene are also included on this page to help spot regulatory motifs ( e.g. poly - u termination signals ) . each trna gene page also includes covariance model search scores that are broken down by contribution from primary sequence patterns versus secondary structures , enabling tentative identification of some types of trna pseudogenes . ( a ) direct link to the genomic locus of the trna gene with the display of related data tracks in the ucsc genome browser ( 3 ) is provided when available . top scoring isotype - specific models are included to illustrate consensus ( or lack thereof ) in isotype classification . the rank of val - aac-41 indicates that it is the fourth highest scoring out of six human val - aac trna genes . an atypical feature for the displayed trna is g50:g64 , a non - watson - crick base pair mismatch in the t - arm . ( b ) expression of trna fragments derived from trna - val - aac using arm - seq were retrieved from published literature ( 13 ) . ( c ) graphic representation of trna secondary structure prediction from trnascan - se was rendered by naview ( 22 ) . ( d ) multiple sequence alignments of trna genes with the same isotype are shown with the stems highlighted and individual scores . ( e ) variants from dbsnp ( 19 ) build 142 located at the trna - val - aac-41 locus are listed with their relative trna positions , alternate alleles , commonality , predicted effects and direct links to the dbsnp website for further information . atypical features which highlight deviations from the canonical trna structure or highly conserved nucleotides ( e.g. g50:g64 , figure 1a ) . rank of isodecoder indicates how highly the current trna scores relative to all other trnas sharing the same anticodon in that genome ; a higher rank may roughly correlate positively with relative usage in translation . in addition to the secondary structure predicted by sequence alignment to the trna covariance model ( included in the original gtrnadb ) , we have now added a contrasting minimum free energy ( mfe ) secondary structure prediction created by rnafold ( 17 ) ( figure 1c ) . it is not yet clear how the mfe structure changes after addition of trna modifications , or how a highly stable non - cloverleaf fold may affect early trna processing , although compiling comparative structure information in the new gtrnadb should facilitate this active area of research . because the most highly accessed species within the gtrnadb are human , escherichia coli k12 , budding yeast and mouse , we have begun to integrate some of the growing wealth of published functional data for these species to put trna gene predictions in richer context . first , we integrated all available rna modification data directly from the extremely valuable modomics database ( 18 ) , as trnas are densely modified and knowledge of these different modifications is critical for better understanding trna function . second , a new method was developed in our lab in collaboration with the phizicky lab ( 13 ) which enables greatly enhanced sequencing of trna fragments , as well as detection of ma , mg and mc modifications across all expressed trnas . to enable easier access to the first global view of trna fragment patterns , we have integrated small rna - seq read profiles for every human and yeast trna from this study ( figure 1b ) , and we plan to continue adding high value expression data as new studies are published . third , we have collected the most recent data on human genome variation from dbsnp ( build 142 ) ( 19 ) , since understanding the potential phenotypic effects of mutations in trna genes is an integral part of understanding their role in human disease . while it has been assumed that multiple copies of trnas offer redundancy in most eukaryotes , it was shown recently that a single point mutation in a single trna gene could cause severe neural degeneration in a particular mouse genetic background ( 6 ) . in order to enable the biomedical research community to identify other important mutations , we have included not only the position of the genomic variants within the trna genes , but also the predicted impact of such mutations given conserved primary and secondary structure of trnas ( figure 1e ) . the goal is to predict the functional consequences of trna gene polymorphisms , similar to predictive programs developed for protein coding genes like snpeff ( 20 ) . a key feature of the new database is its capacity to incorporate new and valuable reference data sets that provide insight into trna gene function as they become available . an example is the wealth of epigenomic information from the encode project measuring transcription factor chip - seq data for a number of proteins found associated with rna polymerase iii transcription ( tbp , brf1 , rpc155 , pol3 and bdp1 ) across five different cell lines ( gm12878 , h1 embryonic stem cells , k562 , hela and hepg2 ) . session views for each trna in the human genome , accessible by clicking on links given in the genome browser view ( figure 2 ) . other tracks displayed in these views , including the 100-vertebrate multi - genome alignments , can allow rapid assessment of the evolutionary conservation and age of each trna gene in the genome . additional types of genome browser views will be added as they become available and relevant to trna biology . example of genome browser views for two human trnas showing evolutionary conservation and encode chip - seq data for rna polymerase iii - associated transcription factors . ( a ) view of trna - val - aac-41 , which has a lower trnascan - se score ( 66.4 bits ) , is less conserved ( fewer alignments to other species in the 100-vertebrate multi - genome alignment & conservation track at bottom ) , and is not as transcriptionally active ( red peaks from encode transcription factor chip - seq data ) as other more canonical val - aac genes . ( b ) view of trna - val - aac-11 , which is a higher scoring trna ( 77.9 bits ) , is more conserved ( across most mammals ) , and much more transcriptionally active ( y - axis scale same as in part ( a ) ) . chip - seq data are from the encode project ( 23 ) using antibodies to tbp ( tata - box binding protein ) and rpc155 ( aka polr3a,155kda rna polymerase iii polypeptide a ) , derived from signal based on uniform processing from the encode integrative analysis data hub at http://ftp.ebi.ac.uk/pub/databases/ensembl/encode/integration_data_jan2011/hub.txt ) . the custom gtrnadb blast server can be used to search any given sequence against all trnas in the database . options include searching for trna matches in all species , or only in one of the three domains of life . as before , standard blast options include being able to set the expect value ( e - value ) threshold or word size ( 5 ) . if trna matches occur in genomes available in the ucsc genome browser ( 3 ) or archaeal / microbial genome browser ( 4 ) , users can view trna hits within the genome browsers by clicking on the provided links . one of the goals in developing the gtrnadb is to provide a facile tool for comparative analysis across multiple genomes . trna sifter allow researchers to query the database with criteria including phylogenetic domain and clade , partial species name , chromosome or scaffold name , any combination of amino acid isotypes and anticodons , number of introns and the existence of a genome - encoded 3-cca . in this new version of gtrnadb , we have added additional search criteria , including maximum and minimum trna score , and number of mismatches identified in the trna secondary structure . results can be viewed in the web browser interface , via links to individual trna information pages , or downloaded for further analysis . as an example , a peculiar trait of the previously mentioned brain - specific trna found in mouse ( 6 ) is that it is the only high - scoring ( > 65 bits ) arg - tct trna in the mouse genome that does not have an intron . is this peculiar intron - less arg - tct evolutionarily shared with humans , vertebrates or more broadly ? one could examine each species trnas individually , but using the trna sifter , one can search for all arg - tct trnas , scoring > 65 bits , which have 0 intron . in a fairly simple single - step query , one can learn that this unique intron - less arg - tct trna is indeed shared broadly among mammals , amphibians , reptiles and birds , but not among insects or nematodes . this type of query should enable researchers to maximize the value of comparative genomics to understand trna evolution and function . with the advent of individual trna information pages , we are now able to introduce many new types of characterization data by linking to or drawing directly from external databases . individual trna gene pages also allow us to encourage links from other databases ( like rnacentral ( 21 ) ) back to specific gtrnadb entries . we aim to advance trna research by continuing to bring together diverse , complementary types of experimental as well as computational analyses in an integrated platform that facilitates both advanced searches and browsing . we plan to expand these functional data links to other species in the future by collaborating with those communities . users are also encouraged to suggest new functionality or other relevant data sets for inclusion . national human genome research institute , national institutes of health [ hg006753 - 02 to t.l . ] . funding for open access charge : nih ( nhgri ) r01 grant to t.l .

transfer rnas represent the largest , most ubiquitous class of non - protein coding rna genes found in all living organisms . the trnascan - se search tool has become the de facto standard for annotating trna genes in genomes , and the genomic trna database ( gtrnadb ) was created as a portal for interactive exploration of these gene predictions . since its published description in 2009 , the gtrnadb has steadily grown in content , and remains the most commonly cited web - based source of trna gene information . in this update , we describe not only a major increase in the number of trna predictions ( > 367000 ) and genomes analyzed ( > 4370 ) , but more importantly , the integration of new analytic and functional data to improve the quality and biological context of trna gene predictions . new information drawn from other sources includes trna modification data , epigenetic data , single nucleotide polymorphisms , gene expression and evolutionary conservation . a richer set of analytic data is also presented , including better trna functional prediction , non - canonical features , predicted structural impacts from sequence variants and minimum free energy structural predictions . views of trna genes in genomic context are provided via direct links to the ucsc genome browsers . the database can be searched by sequence or gene features , and is available at http://gtrnadb.ucsc.edu/.

the korean corneal disease study group ( kcdsg ) is an independent , non - profit , academic society whose members comprise the most active corneal subspecialists in korea . in 2009 , the initial survey on the definition , diagnosis , severity grading , and management of dry eye disease was conducted among the members of the kcdsg . in this survey , we found that 78.8% of kcdsg members use the dews classification as diagnostic guidelines of dry eye disease , while 21.2% use guidelines proposed by the dts group . kcdsg members also responded that they consider subjective symptoms , tear film breakup time ( tbut ) , and signs of ocular surface inflammation of more diagnostic value than other parameters . based on the results of this survey , along with a review of the contemporary literature with regard to definition , classification , and treatment recommendations for dry eye , the subcommittees held face - to - face meetings to reach a consensus on the issues related to the definition , diagnosis , severity grading , and treatment recommendations for dry eye disease . new guidelines for the diagnosis and management of dry eye disease were adopted as shown in tables 1 and 2 . these guidelines were based on dews guidelines and modified to simplify the grading scheme so that they could be used more easily in clinical practice . dry eye disease was defined as " a disease of the ocular surface that is associated with tear film abnormalities . " we agreed that a patient should be diagnosed with dry eye disease when he or she has at least one symptom and one objective sign . in the diagnosis guidelines , dry eye symptoms included ocular symptoms ( such as dryness , discomfort , foreign body sensation , and pain ) and visual symptoms ( such as blurring or vision fluctuation ) . ocular surface staining score by the oxford system , tbut , and schirmer-1 test score were used as objective signs for diagnosing dry eye disease . conjunctival injection , lid problems such as blepharitis , trichiasis , keratinization , or symblepharon , and tear film abnormalities such as debris , decreased tear meniscus , and mucus clumping , were considered signs of ocular surface inflammation , but these findings were not considered during the grading of disease severity . the severity level of the disease was determined when both designated symptoms and signs were present at a certain level . if there was a discrepancy between the patients ' symptoms and signs , the severity level was determined according to the severity level of the objective signs . when several objective signs were present at different levels , the severity level of the disease was determined following ocular surface staining . in addition , we introduced a provisional category of " dry eye suspect , " which is not listed on the grading scheme . the patient was diagnosed with suspected dry eye when he or she had only dry eye symptoms without any objective signs . this was to evaluate the distribution of disease severity at the initial visit , and the treatment recommendation did not include the category of " dry eye suspect . " detailed treatment options for each particular level from level i to level iv were recommended as shown in table 2 . we conducted a multicenter , retrospective observational study to validate the clinical efficacy of the developed guidelines for the diagnosis and management of dry eye . the main interests were : 1 ) distribution of disease severity levels according to the guidelines , 2 ) correlation between severity level and clinical parameters , 3 ) current practice pattern and compliance to the management recommendations , and 4 ) factors that affect clinical outcomes . institutional review board approval was obtained , and the study complied with the tenets of the declaration of helsinki . the medical records of dry eye patients who initially visited any of the 37 of 50 kcdsg member institutes ( listed in the acknowledgements ) from march to august 2010 were reviewed . patients were included regardless of any previous treatment history of dry eye disease . subjective and objective assessments , dry eye therapies , and guideline compliance were analyzed . subjective assessments included ocular symptoms , visual symptoms , ocular surface disease index ( osdi ) , and global assessment by the patient on a scale of 0 to 5 , with 0 being the best and 5 the worst . objective assessments included the schirmer-1 test score , tbut , ocular surface staining score by the oxford scale , and global assessment by the physician on a scale of 0 to 5 , with 0 being the best and 5 the worst . severity level of dry eye disease was determined by the grading scheme of the proposed guidelines . among the patients enrolled , those who had a follow - up visit at 90 7 days were analyzed to validate the clinical efficacy of the developed guidelines . for the purpose of analysis , " improvement " was defined as a decrease in the severity level of dry eye according to the proposed grading scheme at the final visit . " compliant " was defined as selection of initial treatment modality according to the developed guidelines . " under - treatment " was defined as 1 ) selection of an initial treatment modality from among the treatments available that is normally recommended for a milder level of disease and 2 ) use of improper level of treatment modality , with no improvement in disease level . " over - treatment " was defined as selection of an initial treatment modality from among the treatments recommended that was more appropriate for a higher ( more severe ) level of disease . the main outcome measure was the clinical outcome of dry eye after three months of treatment and factors affecting outcome , including compliance to the kcdsg guidelines . a t - test was used to analyze the differences in subjective and objective parameters before and after treatment . maximum likelihood estimation of logistic regression models was used to analyze factors contributing to the clinical outcome . a chi - squared test and fisher 's exact test were used to analyze the association of compliance with the guidelines and clinical outcome . the korean corneal disease study group ( kcdsg ) is an independent , non - profit , academic society whose members comprise the most active corneal subspecialists in korea . in 2009 , the initial survey on the definition , diagnosis , severity grading , and management of dry eye disease was conducted among the members of the kcdsg . in this survey , we found that 78.8% of kcdsg members use the dews classification as diagnostic guidelines of dry eye disease , while 21.2% use guidelines proposed by the dts group . kcdsg members also responded that they consider subjective symptoms , tear film breakup time ( tbut ) , and signs of ocular surface inflammation of more diagnostic value than other parameters . based on the results of this survey , along with a review of the contemporary literature with regard to definition , classification , and treatment recommendations for dry eye , the subcommittees held face - to - face meetings to reach a consensus on the issues related to the definition , diagnosis , severity grading , and treatment recommendations for dry eye disease . new guidelines for the diagnosis and management of dry eye disease were adopted as shown in tables 1 and 2 . these guidelines were based on dews guidelines and modified to simplify the grading scheme so that they could be used more easily in clinical practice . dry eye disease was defined as " a disease of the ocular surface that is associated with tear film abnormalities . " we agreed that a patient should be diagnosed with dry eye disease when he or she has at least one symptom and one objective sign . in the diagnosis guidelines , dry eye symptoms included ocular symptoms ( such as dryness , discomfort , foreign body sensation , and pain ) and visual symptoms ( such as blurring or vision fluctuation ) . ocular surface staining score by the oxford system , tbut , and schirmer-1 test score were used as objective signs for diagnosing dry eye disease . conjunctival injection , lid problems such as blepharitis , trichiasis , keratinization , or symblepharon , and tear film abnormalities such as debris , decreased tear meniscus , and mucus clumping , were considered signs of ocular surface inflammation , but these findings were not considered during the grading of disease severity . the severity level of the disease was determined when both designated symptoms and signs were present at a certain level . if there was a discrepancy between the patients ' symptoms and signs , the severity level was determined according to the severity level of the objective signs . when several objective signs were present at different levels , the severity level of the disease was determined following ocular surface staining . in addition , we introduced a provisional category of " dry eye suspect , " which is not listed on the grading scheme . the patient was diagnosed with suspected dry eye when he or she had only dry eye symptoms without any objective signs . this was to evaluate the distribution of disease severity at the initial visit , and the treatment recommendation did not include the category of " dry eye suspect . " detailed treatment options for each particular level from level i to level iv were recommended as shown in table 2 . we conducted a multicenter , retrospective observational study to validate the clinical efficacy of the developed guidelines for the diagnosis and management of dry eye . the main interests were : 1 ) distribution of disease severity levels according to the guidelines , 2 ) correlation between severity level and clinical parameters , 3 ) current practice pattern and compliance to the management recommendations , and 4 ) factors that affect clinical outcomes . institutional review board approval was obtained , and the study complied with the tenets of the declaration of helsinki . the medical records of dry eye patients who initially visited any of the 37 of 50 kcdsg member institutes ( listed in the acknowledgements ) from march to august 2010 were reviewed . subjective assessments included ocular symptoms , visual symptoms , ocular surface disease index ( osdi ) , and global assessment by the patient on a scale of 0 to 5 , with 0 being the best and 5 the worst . objective assessments included the schirmer-1 test score , tbut , ocular surface staining score by the oxford scale , and global assessment by the physician on a scale of 0 to 5 , with 0 being the best and 5 the worst . severity level of dry eye disease was determined by the grading scheme of the proposed guidelines . among the patients enrolled , those who had a follow - up visit at 90 7 days were analyzed to validate the clinical efficacy of the developed guidelines . for the purpose of analysis , " improvement " was defined as a decrease in the severity level of dry eye according to the proposed grading scheme at the final visit . " compliant " was defined as selection of initial treatment modality according to the developed guidelines . " under - treatment " was defined as 1 ) selection of an initial treatment modality from among the treatments available that is normally recommended for a milder level of disease and 2 ) use of improper level of treatment modality , with no improvement in disease level . " over - treatment " was defined as selection of an initial treatment modality from among the treatments recommended that was more appropriate for a higher ( more severe ) level of disease . the main outcome measure was the clinical outcome of dry eye after three months of treatment and factors affecting outcome , including compliance to the kcdsg guidelines . a t - test was used to analyze the differences in subjective and objective parameters before and after treatment . maximum likelihood estimation of logistic regression models was used to analyze factors contributing to the clinical outcome . a chi - squared test and fisher 's exact test were used to analyze the association of compliance with the guidelines and clinical outcome . the medical records of 1,691 patients were reviewed . excluding 79 cases whose clinical information was insufficient , data on 1,612 patients were analyzed during the initial visit . the mean age was 56.9 ( 13.2 ) years ( range , 19 to 85 years ) , and 81% were female . since only eight patients were considered level 4 by the diagnosis guidelines , the severity of level 3 and level 4 were grouped together ( n = 68 ) for the statistical analysis . of the 1,691 patients , 526 met the follow - up visit criteria and were included for analysis of clinical outcome . treatment was carried out according to the guideline recommendations in 65.0% ( 342 / 526 ) of these patients . over - treatment was evident in 32.3% ( 170 / 526 ) of patients , while under - treatment was evident in 2.7% ( 14 / 526 ) . after three months of treatment , the severity level decreased in 35.6% ( 187 / 526 ) of patients , did not change in 59.7% ( 314 / 526 ) of patients , and increased in 4.8% ( 25 / 526 ) of patients . 2 shows the distribution of severity level at the initial and final visits . at three months , the proportion of level i dry eye increased from 48% to 63% of total patients , and objective signs of dry eye completely resolved with subjective symptoms persisting in 7% of patients ( fig . logistic regression analysis showed that younger age , higher severity level at the initial visit , compliance with the treatment recommendations , and use of topical cyclosporine were significantly associated with improvement in clinical outcomes ( table 4 ) . we also found that distributions of severity level at the initial visit were significantly different among clinical outcome groups ( chi - square test , p < 0.0001 ) ( table 5 ) . discordant with treatment recommendations , therapeutic modalities for severity level ii or above were used for 62.0% ( 158 / 255 ) of level i dry eye patients . however , clinical outcome was not signif icantly improved in the over - treatment group compared to the compliant group in level i patients ( 10.20% vs. 10.76% improvement , p = 0.4316 ) . overall , 47.37% of the patients in the compliant group showed improvement , while 14.71% in the over - treatment group showed improvement ( p < 0.0001 ) ( table 6 ) . the korean guidelines for the diagnosis and management of dry eye are concise , practice - focused , expert consensus recommendations that are simple , intuitive , and easy - to - use in a clinical practice setting . in developing these guidelines , contemporary concepts of diagnosis , grading , and management of dry eye disease were adopted and modified . the members of the kcdsg agreed that dry eye disease should be diagnosed when a patient has at least 1 sign and symptom . however , symptoms may precede signs in certain patients , and it is difficult to exclude short - term fluctuations in symptoms and signs . therefore , we categorized the presence of only dry eye symptoms without ocular signs as suspected dry eye . a patient with suspected dry eye was not listed in the grading system because the general consensus was that dry eye treatment should not be recommended for these patients . the grading system is adopted and modified from the dry eye severity grading scheme of the dews . we gave much weight to patients ' symptoms and ocular surface staining scores in grading the disease severity . ocular signs , such as conjunctival injection , lid abnormalities , and tear film abnormalities were not considered in the grading system because these are common findings in other ocular surface diseases and often overlap with dry eye disease . however , these findings may be regarded as positive ocular signs in the diagnosis of dry eye . the schirmer-1 test score represents the patient 's reflex tear flow and it is used to diagnose aqueous - deficient dry eye disease . however , there is wide intra - patient variation in the test results , and the test is not routinely performed on every dry eye patient in the office . the interesting finding in this study was that no case was diagnosed only by a low schirmer-1 test score without any other objective signs . the patients with low schirmer scores were always accompanied by positive findings in other objective parameters . this result implies that the schirmer-1 test may not be a mandatory parameter in the diagnosis of dry eye disease , although it is useful in the evaluation of tear function . a stepladder approach according to severity level we recommended non - preserved artificial tears for dry eye patients with level ii severity or greater and anti - inflammatory therapy for those with level ii severity or greater . more than 50% of the patients had level i severity or less ( 47.5% patients had level i severity , and only 32.6% ( 526 / 1,612 ) of the total patients were eligible to be included in the analysis of clinical outcomes . high drop - out rates during the follow - up period may raise concerns about selection bias for severe cases . however , distribution of the severity level of these 526 patients was not significantly different from that of the initial visit group . cases of suspected dry eye at the initial visit were excluded from the clinical analysis because the guidelines did not recommend any treatment for such patients . this study showed that the severity level according to our guidelines correlated well with other subjective and objective parameters , including osdi , patient 's global assessment , and physician 's global assessment . although the participating physicians were aware of the treatment recommendation guidelines , they were free to choose treatment modalities using the guidelines and their own clinical judgment . an interesting finding was that many patients with level i severity were treated with therapeutic modalities recommended for higher severity levels , which included mostly anti - inflammatory therapy , and this failed to result in better outcomes . wide use of anti - inflammatory therapy for level i severity patients may be attributed to the fact that most of the participating institutions were referral hospitals . wilson and stulting also reported that many practitioners treated dts severity level 1 with therapies for dts level 2 . although symptomatic improvement has been reported with anti - inflammatory treatments for mild dry eye , most of the treatment guidelines list topical steroids or topical cyclosporine a as treatments for level ii or greater . among anti - inflammatory treatments , clinical improvement was significantly higher with the use of topical cyclosporine a , but not with topical steroids . since we analyzed the data at the initial and final visits only , the effect of topical steroids could have been masked because it is not likely that topical steroids were used during the entire follow - up period . for the purpose of statistical analysis , we defined " improvement " as a decrease in severity level at the final visit . this definition evidently limited the clinical outcome of level i patients , because these patients were required to fall into the category of suspected dry eye at the final visit to show improvement . however , when the treatment guidelines were recommended based on disease severity level , it was not possible to assign clinical significance to any changes in subjective and objective parameters within the same severity level . evaluation of individual treatment modalities contributing to clinical outcomes was limited by the retrospective , non - randomized nature of the study . the korean guidelines for the diagnosis and management of dry eye can be used as a valid and effective tool for the treatment of dry eye disease in clinical practice .

purposeto evaluate the clinical efficacy of newly developed guidelines for the diagnosis and management of dry eye.methodsthis retrospective , multi - center , non - randomized , observational study included a total of 1,612 patients with dry eye disease who initially visited the clinics from march 2010 to august 2010 . korean guidelines for the diagnosis and management of dry eye were newly developed from concise , expert - consensus recommendations . severity levels at initial and final visits were determined using the guidelines in patients with 90 7 days of follow - up visits ( n = 526 ) . groups with different clinical outcomes were compared with respect to clinical parameters , treatment modalities , and guideline compliance . main outcome measures were ocular and visual symptoms , ocular surface disease index , global assessment by patient and physician , tear film break - up time , schirmer-1 test score , ocular surface staining score at initial and final visits , clinical outcome after three months of treatment , and guideline compliance.resultsseverity level was reduced in 47.37% of patients treated as recommended by the guidelines . younger age ( odd ratio [ or ] , 0.984 ; p = 0.044 ) , higher severity level at initial visit , compliance to treatment recommendation ( or , 1.832 ; p = 0.047 ) , and use of topical cyclosporine ( or , 1.838 ; p = 0.011 ) were significantly associated with improved clinical outcomes.conclusionskorean guidelines for the diagnosis and management of dry eye can be used as a valid and effective tool for the treatment of dry eye disease .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Education Savings Assistance Act of 1994''. SEC. 2. TAX TREATMENT OF STATE EDUCATION SAVINGS ACCOUNTS. (a) In General.--Part III of subchapter B of chapter 1 of the Internal Revenue Code of 1986 (relating to items specifically excluded from gross income) is amended by redesignating section 137 as section 138 and by adding after section 136 the following new section: ``SEC. 137. EDUCATION SAVINGS ACCOUNTS. ``(a) General Rule.--Gross income shall not include any qualified education savings account distribution. ``(b) Qualified Education Savings Account Distribution.--For purposes of this section-- ``(1) In general.--The term `qualified education savings account distribution' means any amount paid or distributed out of an education savings account which would otherwise be includible in gross income to the extent such payment or distribution is used exclusively to pay qualified higher education expenses incurred by the designated beneficiary of the account. ``(2) Rollovers.--The term `qualified education savings account distribution' includes any transfer from an education savings account of one designated beneficiary to another such account of such beneficiary or to such an account of another designated beneficiary. ``(3) Special rules.--The determination under paragraph (1) as to whether an amount is otherwise includible in gross income shall be made in the manner described in section 72, except that-- ``(A) all education savings accounts shall be treated as one contract, ``(B) all distributions during any taxable year shall be treated as one distribution, ``(C) contributions to an account described in subsection (c)(4)(B)(i) shall not be included in the basis of the account, and ``(D) the value of the contract, income on the contract, and investment in the contract shall be computed as of the close of the calendar year in which the taxable year begins. ``(c) Education Savings Account.--For purposes of this section-- ``(1) In general.--The term `education savings account' means a trust created or organized in the United States-- ``(A) pursuant to a qualified State educational savings plan, and ``(B) exclusively for the purpose of paying the qualified higher education expenses of the designated beneficiary of the account. ``(2) Qualified state educational savings plan.--The term `qualified State educational savings plan' means a plan established and maintained by a State or instrumentality thereof under which-- ``(A) participants may save to meet qualified higher education expenses of designated beneficiaries, ``(B) planning and financial information is provided to participants about current and projected qualified higher education expenses, ``(C) education savings account statements are provided to participants at least quarterly, and ``(D) an audited financial statement is provided to participants at least annually. ``(3) Qualified higher education expenses.--The term `qualified higher education expenses' means the cost of attendance (as defined in section 472 of the Higher Education Act of 1965). ``(4) Limitations.--A trust shall not be treated as an education savings account unless the following requirements are met: ``(A) No contribution will be accepted unless it is in cash, stocks, bonds, or other securities which are readily tradable on an established securities market. ``(B) Contributions will not be accepted for any taxable year in excess of the applicable limit. The preceding sentence shall not apply to-- ``(i) contributions to the qualified State educational savings plan which are allocated to all education savings accounts within the class for which the contribution was made, or ``(ii) rollover contributions described in subsection (b)(2). ``(C) The trust may not be established for the benefit of more than one individual. ``(D) The trustee is the qualified State educational savings plan or person designated by it. ``(E) The assets of the trust may be invested only in accordance with the qualified State educational savings plan. ``(5) Applicable limit.--For purposes of paragraph (4)(B)-- ``(A) In general.--The applicable limit is $3,000. ``(B) Indexing.--In the case of taxable years beginning after December 31, 1994, the $3,000 amount under subparagraph (A) shall be increased by the education cost-of-living adjustment for the calendar year in which the taxable year begins. ``(C) Education cost-of-living adjustment.--For purposes of subparagraph (B), the education cost-of- living adjustment for any calendar year is the percentage (if any) by which-- ``(i) the higher education cost index for the preceding calendar year, exceeds ``(ii) such index for 1993. ``(D) Higher education cost index.--For purposes of subparagraph (C), the higher education cost index for any calendar year is the average qualified higher education expenses for undergraduate students at both private and public institutions of higher education for the 12-month period ending on August 31 of the calendar year. The Secretary of Education shall provide for the computation and publication of the higher education cost index. ``(d) Tax Treatment of Accounts and State Plans.-- ``(1) Exemption from tax.--An education savings account shall be exempt from taxation under this subtitle. Notwithstanding the preceding sentence, any such account or plan shall be subject to the taxes imposed by section 511 (relating to imposition of tax on unrelated business income of charitable, etc. organizations). ``(2) Loss of exemption of account where individual engages in prohibited transaction.-- ``(A) In general.--If the designated beneficiary of an education savings account is established or any individual who contributes to such account engages in any transaction prohibited by section 4975 with respect to the account, the account shall cease to be an education savings account as of the first day of the taxable year (of the individual so engaging in such transaction) during which such transaction occurs. ``(B) Account treated as distributing all its assets.--In any case in which any account ceases to be an education savings account by reason of subparagraph (A) as of the first day of any taxable year, an amount equal to the fair market value of all assets in the account shall be treated as having been distributed on such first day. ``(3) Effect of pledging account as security.--If, during any taxable year, the individual for whose benefit an education savings account is established, or any individual who contributes to such account, uses the account or any portion thereof as security for a loan, the portion so used shall be treated as distributed to the individual so using such portion. ``(e) Reports.--The Secretary may require the trustee of an education savings account to make reports regarding such account to the Secretary, to the individual who has established the account, and to the designated beneficiary of the account with respect to contributions, distributions, and such other matters as the Secretary may require. The reports required by this subsection shall be filed at such time and in such manner and furnished to such individuals at such time and in such manner as may be required by those regulations.'' (b) Tax Treatment of Qualified State Educational Savings Plan.-- (1) Treatment as section 501(c)(3) organization.--Section 501(c)(3) of such Code is amended by inserting ``or which is a qualified State education savings plan (as defined in section 137(c)(2)),'' after ``animals,''. (2) Charitable contributions.-- (A) Subparagraph (B) of section 170(c)(2) of such Code is amended by inserting ``, or which is a qualified State education savings plan (as defined in section 137(c)(2)),'' after ``animals''. (B) Section 170(b)(1)(A) of such Code is amended by striking ``or'' at the end of clause (vii), by inserting ``or'' at the end of clause (viii) and by inserting after clause (viii) the following new clause: ``(ix) a qualified State educational savings plan (as defined in section 137(c)(2)).'' (c) Contribution Not Subject to Gift Tax.--Section 2503 of such Code (relating to taxable gifts) is amended by adding at the end thereof the following new subsection: ``(h) Education Savings Accounts.--Any contribution made by an individual to an education savings account described in section 137 shall not be treated as a transfer of property by gift for purposes of this chapter.'' (d) Tax on Prohibited Transactions.--Section 4975 of such Code (relating to prohibited transactions) is amended-- (1) by adding at the end of subsection (c) the following new paragraph: ``(4) Special rule for education savings accounts.--An individual for whose benefit an education savings account is established and any contributor to such account shall be exempt from the tax imposed by this section with respect to any transaction concerning such account (which would otherwise be taxable under this section) if, with respect to such transaction, the account ceases to be an education savings account by reason of the application of section 137(d)(2)(A) to such account.'', and (2) by inserting ``, an education savings account described in section 137(c),'' in subsection (e)(1) after ``described in section 408(a)''. (e) Failure To Provide Reports on Education Savings Accounts.-- Section 6693 of such Code (relating to failure to provide reports on individual retirement accounts or annuities) is amended-- (1) by inserting ``or on education savings accounts'' after ``annuities'' in the heading of such section, and (2) by adding at the end of subsection (a) the following new sentence: ``Any person required by section 137(e) to file a report regarding an education savings account who fails to file the report at the time or in the manner required by such section shall pay a penalty of $50 for each failure, unless it is shown that such failure is due to reasonable cause.'' (f) Special Rule for Determining Amounts of Support for Dependent.--Subsection (b) of section 152 of such Code (relating to definition of dependent) is amended by adding at the end the following new paragraph: ``(6) A distribution from an education savings account described in section 137(c) to the individual for whose benefit such account has been established shall not be taken into account in determining support for purposes of this section to the extent such distribution is excluded from gross income of such individual under section 137.'' (g) Clerical Amendments.-- (1) The table of sections for part III of subchapter B of chapter 1 of such Code is amended by striking out the item relating to section 137 and inserting the following new items: ``Sec. 137. Education savings accounts. ``Sec. 138. Cross references to other Acts.'' (2) The table of sections for subchapter B of chapter 68 of such Code is amended by striking out the item relating to section 6693 and inserting the following new item: ``Sec. 6693. Failure to provide reports on individual retirement accounts or annuities or on education savings accounts.'' (h) Effective Date.--The amendments made by this section shall apply to contributions made in taxable years beginning after December 31, 1993.

Education Savings Assistance Act of 1994 - Amends the Internal Revenue Code to exclude from gross income any qualified education savings account. Describes such account as a trust created pursuant to a State educational savings plan and used exclusively to pay the higher education expenses of the designated beneficiary. Treats such State plans as tax-exempt organizations and treats contributions to such plans as charitable contributions. Declares that contributions to such accounts are not subject to the gift tax. Imposes penalty taxes in connection with reporting requirements or prohibited transactions associated with an account. Excludes distributions from such accounts when determining support for dependents.

dynamical systems in nature are rarely isolated . interactions between the dynamical units often give rise to new phenomena which can be exploited in different contexts in physical , biological and social sciences @xcite . among them , the recently discovered emergent phenomenon of chimera states has been in the center of recent research towards the study of coupled networks . in the chimera state the synchronous and asynchronous behaviors are observed simultaneously in a network of coupled identical oscillators . chimera state was first reported by kuramoto et al . in nonlocally coupled phase oscillators @xcite . the fascinating phenomenon was initially found in nonlocal coupling configurations @xcite . however more recent results reveal that the systems with globally @xcite and locally coupled oscillators @xcite are also capable of showing such phenomenon . recently such states have also been explored in experiments with optical @xcite , electronic @xcite , electrochemical @xcite , and mechanical oscillators @xcite . such a remarkable phenomenon has been subsequently studied for a variety of systems including chemical oscillators @xcite , neuron models @xcite , planar oscillators@xcite , heterogeneous systems @xcite , oscillators with more than one populations @xcite as well as in hierarchical networks @xcite and also in a variety of system structures such as rings , networks with two and three oscillator populations @xcite and two dimensional map lattices @xcite . several other chimera patterns like chimera death states @xcite and phase - flip chimera states @xcite have been recently explored . for instance , in ref . @xcite , abrams et al . studied the stability of the chimera states in two interacting populations of globally coupled phase oscillators where one population is synchronized and the other population is desynchronized . it does not contain synchronized oscillators from both the populations . they have also shown that the chimera states are stable and stationary , and that these states become periodically breathing chimera states due to stability change . later pikovsky and rosenblum @xcite have observed quasiperiodic chimera states in the same model considered in ref . @xcite by nonuniformly distributing the initial conditions . on the other hand , globally clustered chimera ( gcc ) states were reported by sheeba , chandrasekar and lakshmanan @xcite in the case of delay coupled phase oscillators . they have shown that the existence of such states can be achieved by tuning the delay parameter . whereas many of the studies related to the chimera patterns have been focusing on the networks of phase oscillators , in this work we address the question as to how the emergence of chimeras arise in two distinct groups of identical populations of stuart - landau oscillators where variations in amplitudes also occur . here the interaction between the oscillators are equally shared by both the populations . one important fact to be noted here is that the frequencies of the oscillators are identical within their population but have a finite difference among the two groups . our system is different from the system considered in ref . @xcite where the authors assumed that the oscillators within a population are coupled strongly with each other than that with the neighboring population and also differ from the system considered in ref.@xcite , where laing assumed the two populations of phase oscillators with nonidentical natural frequencies . recently , in ref . @xcite , the authors have identified transition from cluster states to extensive chaos and then to incoherent state while decreasing the system parameter in an identical population of globally coupled stuart - landau oscillators . our motivation in this paper is to investigate the occurrence of chimera - like states by considering two distinct groups ( each one is characterized by its own frequency ) of identical populations of stuart - landau oscillators which are coupled through ( i ) global and ( ii ) nonlocal couplings . we study the characteristic behavior of the oscillators by fixing the frequency of the oscillators in one population while varying the frequency of the oscillators in the other population . we find the occurrence of different dynamical states including local synchronization , local cluster states , chimera - like states , global cluster states and global synchronization in globally coupled oscillators . among these dynamical states , chimera - like states occur only for a sufficient range of frequency mismatch and all the oscillators are coupled through equal coupling interaction . in contrast to the chimera states found in a single array of coupled identical oscillators , the present case of chimera - like states ( where synchronized oscillations occur in one population while another population is in a fully desynchronized state ) exist in two distinct groups of identical populations with a frequency mismatch between them . it occurs neither for a very low mismatch nor for a larger mismatch of frequencies . these states are different from chimera states found in coupled identical oscillators in which total number of oscillators are split into coexisting domains of synchronized and desynchronized oscillations @xcite . further , we also find that the chimera states exhibiting synchronized and desynchronized oscillations in nonlocally coupled two distinct groups of identical populations are different from the globally coupled case for the reason that in the previous case , synchronized and desynchronized oscillators exist in one population while another population shows synchronized oscillations . existence of such a state is independent of frequency mismatch between the two populations under nonlocal coupling and exist for spatially prepared initial conditions . perturbation from such initial states leads to imperfectly synchronized states in this region . in globally coupled system , we find the multistability in the system depending on the initial conditions used . on the other hand , a nonlocally coupled system does not show any multistability region except in the cluster region . ) with segment @xmath0 ( red / grey dots ) , ( b ) for desynchronized oscillator ( @xmath1 ) with data set @xmath2 ( red / grey dots ) , ( c ) for desynchronized oscillator ( @xmath3 ) with segment @xmath4 ( red / grey dots ) , ( b ) for desynchronized oscillator ( @xmath5 ) with data set @xmath6 ( red / grey dots ) . ] the structure of the paper is organized as follows : in sec . ii we describe our model of two distinct groups of identical populations of globally coupled oscillators . in sec . iii we discuss the existence of various dynamical states by introducing the frequency mismatch between the populations in the above globally coupled oscillators with two parameter phase diagrams . in sec . iv we discuss how the dynamics of nonlocally coupled oscillators get affected by the presence of frequency mismatch between them . finally we critically summarize our results in sec . we consider two distinct populations of globally coupled stuart - landau oscillators for our analysis , by assuming the same common frequencies within a population and different frequencies between the populations . the governing equations are specified by the following set of equations , @xmath7 where @xmath8 , @xmath9 . there are @xmath10 oscillators in the population - i and they are numbered as @xmath11 while @xmath12 oscillators are in the population - ii and they are numbered as @xmath13 . @xmath14 and @xmath15 is the total number of oscillators . in our study , we consider both the populations to be of equal size , @xmath16 . for a discussion on @xmath17 , see the last paragraph of sec . iii below . in eq . ( [ glo ] ) , @xmath18 is the coupling constant and @xmath19 is the nonisochronicity parameter , @xmath20 and @xmath21 are the natural frequencies of the oscillators in the two populations of the network . this model can also be considered as a single population with two clustered networks . in our simulations , we choose the number of oscillators @xmath15 to be equal to 200 and in order to solve the equation ( [ glo ] ) , we use the fourth order runge - kutta method with time step 0.01 and the initial state of the oscillators ( @xmath22 ) are distributed with uniform random values between -1 and + 1 . we have also verified that the results are independent of increasing the number of oscillators in the population . to start with , by assuming @xmath23 , @xmath24 in ( [ glo ] ) , we consider a small frequency difference between the two populations such that @xmath25 . to explore the results of different dynamical behaviors , we present the associated space - time plots in figs . [ global](a - e ) . for small values of the coupling strength of the oscillators , both the populations are individually synchronized with two different average frequencies ( frequency profiles of the oscillators are discussed below in fig . [ freq ] ) , see figs . [ global](a ) and [ global](f ) . this means that the oscillators are having the same average frequency within their population but they are different for different populations . by increasing the coupling strength to @xmath26 the system of oscillators in population - i splits into two groups . these two groups are oscillating synchronously with same frequency though there is a finite phase difference between the two groups , while the population - ii remains oscillating synchronously . they are clearly illustrated with the space - time plot in fig . [ global](b ) and with a snapshot of the variables in fig . [ global](g ) . hence these states are designated as local cluster states . upon increasing the strength of coupling interaction to @xmath27 one observes that the mismatch between the frequencies of two populations causes asynchronous oscillations among the oscillators in population - i while the population - ii remains synchronized which denotes the existence of chimera - like states . in contrast to the chimera states found in a single array of coupled identical oscillators , the present case of chimera - like states exist in two identical populations with a frequency mismatch between them . figure [ global](c ) represents the space - time plot for the chimera - like state . its snapshot in fig . [ global](h ) confirms the coexistence of spatially coherent and incoherent distributions of oscillators . in this state the high frequency population remains synchronized having the same average frequency while the low frequency population is desychronized with its oscillators having different average frequencies . on increasing @xmath18 to @xmath28 we note that the system enters into the global cluster state as shown in fig . [ global](d ) . in this state the total number of oscillators in both the populations are grouped into two groups ( fig . [ global](i ) ) . these two groups are entrained to a common average frequency but with different amplitudes . we can observe the globally synchronized oscillations ( with same frequency , amplitude and phase ) among the oscillators for @xmath18 beyond @xmath29 . on order to confirm the existence of chimera - like states , we analyze the phase - locking behaviour of the synchronized and desynchronized oscillators through the following localized set approach @xcite . to illustrate this approach , we choose one of the representative oscillators from both the synchronized and desynchronized groups . first , we construct a data set @xmath2 by observing the desynchronized oscillator @xmath30 whenever the trajectory of synchronized oscillator @xmath31 crosses the segment @xmath32 . in fig . [ phasep](a ) , the attractor of synchronized oscillator @xmath31 is shown by black curve and red / grey line represents the segment @xmath0 . the attractor of the desynchronized oscillator @xmath30 is depicted by black curve and the data set @xmath2 is shown by the red / grey dots in fig . [ phasep](b ) and in which the spreading of the data set over the trajectory clearly illustrates that the deysnchronized oscillator is not in phase with the synchronized oscillator . further , we also illustrate the non - phase locking behaviour between the desynchronized oscillators in figs . [ phasep](c ) and ( d ) . the attractor and corresponding segment of one of the randomly chosen representative oscillators @xmath33 are shown by the black curve and red / grey line in fig . [ phasep](c ) . in fig . [ phasep](d ) , we can observe that the data set @xmath34 corresponding to the oscillator @xmath5 is spread over the trajectory @xmath5 . this also clearly illustrates that there is no phase locking between the desynchronized oscillators . thus we confirm that the existence of chimera - like states which is illustrated in figs . [ global](c ) and ( h ) . the chimera - like states are distinguished from the intermittent chimera states @xcite and quasi - periodic chimera states @xcite that are observed in two populations of coupled rotators where the authors have considered broken - symmetry conditions realized by initializing the first population with identical phases and frequencies while they are random for second population . note that the important fact to be noted here is that the frequencies of the oscillators are identical within their population but have a finite difference among the groups . also the initial conditions are chosen uniformly between @xmath35 and @xmath36 . , @xmath37 . enlarged structures for a specific value of @xmath38 : ( b ) average frequencies of the synchronized oscillators ( population - ii ) . ( c ) frequencies of the desynchronized oscillators ( population - i ) . b. corresponding to the evolution in the complex plane , snapshots of the variables @xmath39 : ( i)-a and b correspond to desynchronization for @xmath40 ( region - i ) , ( ii)-a , b correspond to local synchronization for @xmath41 ( region - ii ) , ( iii)-a , b represent local cluster states for @xmath26 ( region - iii ) , ( iv)-a , b represent the chimera - like states for @xmath27 ( region - iv ) , ( v)-a , b represent the global cluster states for @xmath28 ( region - v ) ( vi)-a , b corresponds to global synchronization fro @xmath42 ( region - vi ) . trajectories are shown by black solid lines and red / grey dots represent the snapshots of the variables @xmath43 in the complex plane . ] to give more details about the nature of the dynamical states ( discussed above ) , we present the frequency of the oscillators as a function of the coupling strength ( @xmath18 ) in figs . [ freq ] ( a ) . we calculate the average frequencies of the oscillators by using the expression @xmath44 , where @xmath45 is the number of maxima in the time series @xmath46 over a time interval @xmath47 . also for a clear understanding about the dynamical regions , we have plotted the evolution of the dynamical variables in the complex plane @xmath48 and their respective snapshots of the variables @xmath49 are projected onto the complex plane in fig . [ freq ] b(i - vi ) . in fig . [ freq ] a(a ) , initially for the range between @xmath50 , the oscillators are having same frequency within populations but they are oscillating incoherently as shown in figs . [ freq]b(i)-a and ( i)-b . for the range @xmath51 , we can observe local synchronizations , that is each population is individually synchronized with two different frequencies represented by region - ii in fig . [ freq ] a(a ) . figs . [ freq ] b(ii)-a and ( ii)-b clearly show the individual synchronization . in the region @xmath52 , we can observe local cluster states . in this state , oscillators in the low frequency population separate into different synchronized groups ( figs . [ freq ] b(iii)-a and ( iii)-b ) . but their frequencies are the same while the high frequency population remains synchronized with a single frequency as shown in the region - iii in fig . [ freq ] a(a ) . upon increasing @xmath18 to @xmath53 , we can observe chimera - like states in the region - iv in fig . [ freq ] a(a ) where the coherent oscillators are oscillating with the same frequency while the incoherent oscillators are having different frequencies which are clearly shown in figs . [ freq ] a(b ) and a(c ) . figs . [ freq ] b(iv)-a and ( iv)-b also validate the chimera - like behaviour where the incoherent oscillators are randomly distributed in the complex plane while the distribution of the synchronized oscillators are shown by the red / grey dot . further for the values of @xmath18 between 2.25 to 2.8 , one can find global cluster states where the frequencies of all the oscillators ( in both the populations - i and ii ) are the same as illustrated in region - v of fig . [ freq ] a(a ) ( and further confirmed by figs . [ freq ] b(v)-a and ( v)-b ) . finally , beyond the value @xmath54 , both the populations are globally synchronized to a common frequency , see region vi in fig . [ freq]a(a ) and figs . [ freq ] b(vi)-a and ( vi)-b . by considering the various dynamical states described above , except for the chimera - like state and global cluster state , all the oscillators in each of the populations possess the same amplitude ( note that in the local cluster region also the amplitudes @xmath55 remain the same ) . hence in order to study analytically the regions of local and global synchronizations , we assume that the amplitudes of all the oscillators remain the same to find the regions of local and global synchronizations . by substituting @xmath56 in equation ( 1 ) we will get @xmath57 if we substitute @xmath58 so that @xmath59 , we will get the phase equation as @xmath60 complex order parameter within each population is described by @xmath61 . replacing the summation term by the complex order parameter , equation ( [ pe ] ) becomes , @xmath62 in the case of local synchronization region ( ls ) , oscillators within each group are identical and so the local order parameter @xmath63 ( red dashed and black solid line ) while the global order parameter @xmath64 ( blue / dark - grey solid line ) which is shown in fig . [ a1](a ) . note that the global order parameter is defined through @xmath65 , where @xmath66 measures the degree of global synchrony for the entire system . in the region gs , we can observe the global synchronization and the values of both @xmath66 and @xmath67 are unity as shown in fig . [ a1](e ) . the critical value of coupling strength at which global synchronization occurs is given by @xcite @xmath68 where @xmath69 $ ] . from the linear stability analysis of eq . ( [ rt ] ) , we will get the eigenvalues for in - phase synchronized states @xcite as @xmath70 where @xmath71 $ ] . the choice @xmath72 leads to the curve @xmath73 shown by the red / grey curve in fig . [ a1](a ) and it matches with the numerically obtained boundary . different dynamical regions in fig . [ a1](a ) for @xmath74 and ( b ) for @xmath75 are identified with the help of strength of incoherence @xcite for every choice of @xmath18 and @xmath19 values . some details on strength of incoherence are given in appendix a. fig . [ a1](a ) represents local synchronization where the local order parameters @xmath76 ( black solid curve ) , @xmath77 ( red dashed curve ) and global order parameter @xmath64 ( blue / dark - grey solid curve ) . in the regions corresponding to local cluster states ( lc ) , chimera - like states ( cs ) and global cluster states ( gc ) , we can observe the local order parameters @xmath77 ( black solid curve ) , @xmath78 ( red dashed curve ) and global order parameter @xmath64 ( blue / dark - grey solid curve ) which are depicted with figs . [ a1](b ) , ( c ) and ( d ) . in globally synchronized region , both @xmath67 and @xmath66 take the value unity which is shown in fig . [ a1](e ) . the region - i is the multistability region between local synchronization and local cluster states . the region-@xmath79 is the multistability region between the local cluster states and complete synchronization . also there arises a multistability region between chimera - like states and complete synchronization in region-@xmath80 . similarly , region-@xmath81 represents the multistability region between the global cluster states and complete synchronization . the regions ls , lc , cs , gc and gs are always stable , that is in these regions even for a small perturbation of the initial state of the oscillators from the completely synchronized solution leads to the regions ls , lc , cs , gc and gs , respectively . there also arises a question whether the chimera - like states are robust to increasing or decreasing the mismatch of frequencies . to address this question , we now present the existence of dynamical states in the parametric space ( @xmath82 ) . ) by varying the values of @xmath83 and @xmath18 ( a ) for @xmath84 and ( b ) for @xmath37 . boundary @xmath85 is obtained from the critical value of the coupling strength given in eq . ( [ cc ] ) . the curve @xmath73 is obtained from eq . ( [ ev ] ) and the other boundaries are obtained numerically . the region ds represents the desynchronized state , ls is the local synchronization region , gs shows the globally synchronized state , gc shows the state corresponding to global cluster region , cs shows chimera states , and lc shows the local cluster state . the region - i is the multistability region between the local synchronization and local cluster states . ] (= @xmath86 ) as a function of the nonisochronicity parameter @xmath19 for fixed @xmath18 values ( @xmath87 for local synchronization , @xmath88 for local cluster states , @xmath89 for chimera - like states , and @xmath90 for global cluster states ) and ( b ) the value of @xmath91 (= @xmath86 ) as a function of the coupling strength @xmath92 for a fixed @xmath37 . note that @xmath93 , where @xmath94 is the earliest coupling strength . dots ( @xmath95 ) represent the numerical data and the corresponding best fit is represented by the ( black ) curve for the chimera - like states . similarly the local synchronization , local cluster states and global cluster states are represented by the solid line with ( @xmath96 ) , ( @xmath97 ) and ( @xmath98 ) , respectively . note that @xmath99 for local synchronization , @xmath100 for local cluster state , @xmath101 for chimera - like state and @xmath102 for global cluster state . other parameter value : @xmath74 ] in order to analyze the global picture of the dynamical system under the influence of frequency mismatch , we plotted the two parameter phase diagrams in the parametric space ( @xmath104 ) for two different nonisochronicity parameter values , that is @xmath84 and @xmath37 , which are illustrated in figs . [ a2](a ) and ( b ) , respectively . in these figures , the curve @xmath85 is obtained from the critical value of the coupling strength for globally synchronized region given in eq . ( [ cc ] ) . the curve @xmath105 is obtained from eq . ( [ ev ] ) and the other boundaries are obtained numerically . these regions are identified with the help of strength of incoherence @xcite . in fig . [ a2](a ) , we can observe that for a range of frequency mismatch @xmath106 , the system of oscillators attains global synchronization through local synchronization . further increasing the frequency mismatch beyond @xmath107 , the system attains global synchronization , through local synchronization , local cluster and global cluster states . from fig . [ a2](b ) , we can find that for a sufficiently small value of frequency mismatch ( @xmath108 ) , global synchronized state is mediated through local cluster states as well as through the global cluster states from individual synchronized states . here , one can not observe the existence of chimera states . interestingly , we can observe the onset of chimera states only in the range @xmath109 . beyond this range of frequency mismatch one can not observe the presence of chimera states . thus we conclude that for only a sufficiently large value of frequency mismatch ( @xmath83 ) one can induce the onset of chimera - like states . we can also observe that the chimera - like states inherit from out of local cluster states . also the chimera - like states mediate between the local cluster states and global cluster states and are quite different from the results in ref . @xcite , where the authors have demonstrated the emergence of chimera states in a system of globally coupled stuart - landau oscillators . such chimera states have inherited properties from the cluster states in which they originate . in figs . [ a2](a ) and ( b ) , the locally synchronized region ( ls ) and local cluster ( lc ) regions are always stable . the region - i is the multistability region between the local synchronization and local cluster states . in this region , for initial conditions near the globally synchronized state one is lead to complete synchronization among the oscillators . also one can check numerically that the chimera - like states and globally clustered states are always stable . the above discussed results are observed for the case where both the populations are of equal size ( @xmath110 ) . there arise a question about the robustness of the dynamical states for the case when @xmath111 . to illustrate this , we decrease the number of oscillators ( @xmath10 ) in population - i so that the number of oscillators ( @xmath12 ) in population - ii becomes @xmath112 . then we find the critical value of @xmath91 ( ( that is @xmath113 ) ) at which there occurs no qualitative change in the dynamical states as a function of nonisochronicity parameter @xmath19 . note that if the value of @xmath91 is unity it represents that both the populations have equal number of oscillators . [ log ] ( a ) shows the log - log plot for the critical value of @xmath91 against the nonisochronicity parameter @xmath19 for fixed @xmath18 value ( we have fixed @xmath87 for local synchronization , @xmath88 for local cluster states , @xmath89 for chimera - like states , and @xmath90 for global cluster states ) . we can observe that the critical value of @xmath91 follows the power law relation @xmath114 with c for the local synchronization region and the best curve fit is obtained for the values @xmath115 and @xmath116 which is shown by the solid line with ( @xmath96 ) in fig . [ log ] ( a ) . similarly the dynamical regions corresponding to local cluster , chimera - like states and global cluster states are illustrated by the solid lines with ( @xmath117 ) , ( @xmath95 ) and ( @xmath98 ) , respectively . the values of @xmath91 follow the power law relation with @xmath19 for the parameter values @xmath118 , @xmath119 in the local cluster region , @xmath120 , @xmath121 in the chimera - like states region and @xmath122 , @xmath123 in the global cluster region . similarly , fig . [ log ] ( b ) is plotted for the critical value of @xmath91 against the coupling strength @xmath92 for a fixed @xmath37 . note that @xmath93 , where @xmath94 is the earliest coupling strength which is different for different dynamical regions for a fixed nonisochronicity parameter . to obtain the best curve fit , we subtract the consecutive @xmath18 values with the @xmath94 value ( that is @xmath99 for local synchronization , @xmath100 for local cluster state , @xmath101 for chimera - like state and @xmath102 for global cluster state ) . here also we can observe that @xmath91 follows the power law relation with coupling strength @xmath18 for the parameter values @xmath124 , @xmath125 in the local synchronization region , @xmath126 , @xmath127 in the local cluster region , @xmath128 , @xmath129 in the chimera - like states region and @xmath130 , @xmath131 in the global cluster region . in the previous section , we have analyzed the existence of chimera - like states which represent asynchronous oscillations in one population and synchronous oscillations in the second population in globally coupled oscillators under the influence of frequency mismatch . to investigate how the dynamics of nonlocally coupled oscillators is affected by the frequency difference between the two populations , we consider the dynamical equations of the following form : @xmath132 where @xmath133 is the total number of nearest neighbors , @xmath134 is the number of oscillators in each population ( @xmath16 ) , @xmath15 is the total number of oscillators in both the populations ( @xmath14 ) , @xmath135 is the coupling range . when @xmath136 , one has nonlocal coupling . in the present study , we are interested to analyze the chimera states in two distinct groups of identical populations of nonlocally coupled oscillators . here the intra - populations of oscillators are globally connected and the oscillators are nonlocally connected with inter - populations . for simplicity , we choose the coupling interaction @xmath137 = @xmath138 = @xmath18 in eq . ( [ two ] ) throughout this section . in order to analyze the dynamics of the system under nonlocal coupling , we present the spatiotemporal evolution , snapshots and the corresponding frequency profiles @xmath139 of the oscillators for various values of coupling strength @xmath18 with fixed coupling range @xmath140 , @xmath74 and nonisochronicity parameter @xmath37 in fig . [ n1 ] . for a small value of coupling strength @xmath141 , we can observe the local synchronization ( figs . [ n1](a ) and ( e ) ) where the oscillators in each of the populations are entrained to two different common frequencies as shown in fig . [ n1](i ) . note that there is a finite frequency difference between them . further increasing coupling strength to @xmath142 , in figs . [ n1](b ) and ( f ) we can observe the solitary states in population - i where such states represent the fact that some of the oscillators escape from the synchronized group and exhibit non - phase coherent oscillations while we find synchronization in population - ii where the oscillators exhibit periodic oscillations . figure [ n2](a ) shows the phase portrait of the desynchronized oscillator @xmath143 which shows the non - phase coherent oscillations of this oscillator and in fig . [ n2](b ) we can observe the periodic oscillation of the synchronized oscillator @xmath144 . another point is that the average frequency of the synchronized oscillators from both the populations are same while the average frequency of the solitary oscillators are different as shown in fig . [ n1](j ) . by increasing the coupling strength to @xmath145 , the system of oscillators gets split into two groups of synchronized oscillations with periodic motion which is shown in figs . [ n1](c ) and ( g ) . these two groups are oscillating with common average frequency ( as in fig . [ n1](k ) ) but with different amplitudes . these states are designated as cluster states . upon increasing the coupling strength to @xmath27 , all the oscillators are entrained to a common frequency with the same amplitude while they are oscillating periodically . their spatiotemporal plot , snapshots and frequency profile are shown in figs . [ n1](d ) , ( h ) and ( l ) , respectively . ) in population - i . ( b ) represents the periodic oscillation of the oscillator ( @xmath144 ) in population - ii . ] , @xmath19 ) parametric space ( a ) for @xmath146 and ( b ) for @xmath147 with @xmath140 for the two population nonlocally coupled stuart - landau oscillators . ds represents the desynchronized region , ls represents the local synchronization region , is shows the imperfectly synchronized states , cl is for cluster state region and gs represents the globally synchronized region . ] in order to explore the results in more detail , we present the global picture in terms of a two phase diagrams in the ( @xmath18 , @xmath19 ) parametric space for two different @xmath148 values with fixed coupling range @xmath140 . various dynamical states observed in fig . [ nlocala ] are identified by making use of the concept of strength of incoherence @xcite ( see appendix for more details ) . from fig . [ nlocala](a ) ( for @xmath149 ) , we can find that the oscillators are initially for low range of @xmath18 ( and for all vales of c ) exhibiting desynchronized oscillations . by increasing the @xmath18 value , the system of oscillators attains local synchronization for a range of @xmath18 values for a given nonisochronicity parameter value . upon further increasing the coupling interaction , we can observe the solitary states in population - i and synchronized oscillations in population - ii . this region is marked as imperfectly synchronized state ( @xmath150 ) in fig . [ nlocala ] . note that the is state is different from the imperfect chimera state reported in ref . @xcite and this state is characterized by a certain small number of solitary oscillators which escapes from the synchronized part of chimera state ( where solitary oscillator represents a single repulsive oscillator splitting up from the fully synchronized group ) . such escaped oscillators oscillate with different average frequencies . the is state is also different from the imperfect chimera state reported in ref . @xcite where the chimeras are characterized by the coexistence of two coherent oscillators and one incoherent oscillator ( i.e. rotating with another frequency ) . if the chimera state loses its ` perfection ' in the sense that phases of the synchronized oscillators become not equal , they still rotate with the same average frequency . in this region , we can also observe the existence of chimera states in population - i while synchronized oscillations in population - ii for the specific choice of initial conditions . if we perturb the system from this specific choice of initial state of the oscillators , the system enters into the imperfectly synchronized states . this kind of chimera state is different from the state observed in global coupling . in the case of globally coupled system , one can observe desynchronized oscillations in population - i and synchronized oscillations in population - ii , whereas in the present case of nonlocally coupled system , we find the coexistence of coherent and incoherent domains in population - i and coherent oscillations in population - ii . by increasing the strength of the coupling interaction beyond the @xmath150 region , the system of oscillators enters into the cluster states ( cl ) . further strengthening of the interaction strength leads to global synchronization . in the cl region , the distribution of initial states near the synchronized solution leads to complete synchronization . the cluster states are observed for the initial conditions away from the synchronized solution . similarly for the case of @xmath151 illustrated in fig . [ nlocala](b ) , the system of oscillators follows similar transition routes as that of the case @xmath149 except for the fact that the dynamical regions ls and is are widened in the @xmath18 space . , @xmath83 ) parametric space ( a ) for @xmath84 and ( b ) for @xmath37 with @xmath140 for a system of two distinct identical groups of nonlocally coupled stuart - landau oscillators . ds represents the desynchronized region , ls represents the local synchronization , is shows the imperfectly synchronized states , cl is for cluster state region and gs represents the globally synchronized region . ] next we analyze whether the emergence of imperfectly synchronized states ( or chimera states for spatially prepared initial conditions ) are robust to an increase of frequency mismatch between the two populations . to illustrate the results , we plotted the two parameter phase diagrams in the ( @xmath152 ) parametric space in figs . [ nlo](a , b ) for @xmath84 and @xmath37 values , respectively , with fixed coupling range @xmath140 . in fig . [ nlo](a ) , initially the system of oscillators is desynchronized for small values of coupling strength . by increasing @xmath18 in the range @xmath153 , the system attains global synchronization ( gs ) through the locally synchronized states ( ls ) and imperfectly synchronized ( is ) states . for @xmath154 , the system attains global synchronization ( gs ) through the cluster states ( cl ) in addition to the locally synchronized states ( ls ) and imperfectly synchronized states ( is ) . by increasing the value of @xmath19 to @xmath37 , the system attains global synchronization ( gs ) through the locally synchronized states ( ls ) , imperfectly synchronized states ( is ) and cluster states ( cl ) for all values of frequency mismatch between the populations as shown in fig . [ nlo](b ) . in figs . [ nlo](a ) and ( b ) , the regions is and cl are multistable regions for the reason that even for small perturbations of initial states from the synchronized state leads to the existence of imperfectly synchronized states and cluster states in the regions is and cl , respectively . also in the is region , we can observe the onset of chimera states for specific choice of initial conditions . we can observe that the existence of chimera state is independent of frequency mismatch between the two populations under nonlocal coupling , whereas in the case of global coupled system the existence of chimera state is obtained for only a range of frequency mismatch . we have also analyzed the results for a wide range of nonlocal coupling by plotting the two parameter phase diagram in the ( @xmath155 ) parametric space with two different @xmath83 values that is @xmath146 and @xmath151 for fixed @xmath37 . figures [ re](a ) and ( b ) clearly illustrate the existence of imperfectly synchronized states ( or chimera states for spatially prepared initial conditions ) and other dynamical states for a wide range of nonlocal coupling independent of the frequency mismatch . , @xmath156 ) parametric space ( a ) for @xmath146 ( b ) for @xmath151 with @xmath37 for the system ( [ two ] ) . ds represents the desynchronized region , ls represents the local synchronization , is shows the imperfectly synchronized states , cl is for cluster state region and gs represents the globally synchronized region . ] in summary , we have illustrated the existence of different dynamical states in globally and nonlocally coupled systems of two distinct groups of identical populations of oscillators . we have analyzed the impact of frequency mismatch between the two populations . an interesting feature here is that only for certain ranges of frequency mismatch , one can observe the onset of chimera - like states in globally coupled network and the oscillators are coupled with equal strength coupling interaction . these states are different from the chimera states observed in coupled identical populations where the total number of oscillators are split into coexisting domains of synchronized and desynchronized oscillations . we have found the results are robust for certain range of unequal size populations ( both the populations contain unequal number of oscillators ) . in addition , we have found the existence of multistable regions depending on the initial state of the oscillators . further we have extended our study to analyze the dynamics of nonlocally coupled oscillators where we find the existence of chimera state for spatially prepared initial conditions . in contrast to the global coupling , existence of chimera states is independent of the increase of frequency mismatch between the two populations . in contrast to the case of global coupling , multistability does not exist in nonlocally coupled system except in the cluster state region . finally , it may be an interesting open problem to extend this study to a network of more than two populations , which we are pursuing currently . the work of vkc is supported by the serb - dst fast track scheme for young scientists under grant no.yss/2014/000175 . the work of ms forms part of a research project sponsored by dst , government of india . ml acknowledges the financial support under a nasi platinum jubilee senior scientist fellowship program . to identify the nature of different dynamical states , we look at the strength of incoherence of the system a notion introduced recently by gopal , venkatesan and two of the present authors@xcite , that will help us to detect interesting collective dynamical states such as synchronized state , desynchronized state , and the chimera state . for this purpose we introduce a transformation @xmath157 @xcite , where @xmath158 . we divide the oscillators into @xmath159 bins of equal length @xmath160 and the local standard deviation @xmath161 is defined as @xmath162 from this we can find the local standard deviation for every @xmath159 bins of oscillators that helps to find the strength of incoherence @xcite through @xmath163 where @xmath164 is the threshold value which is small . here @xmath165 represents the average over time . when @xmath161 is less than @xmath164 , @xmath166 takes the value @xmath167 , otherwise it is @xmath168 . thus the strength of incoherence measures the amount of spatial incoherence present in the system which is zero for the spatially coherent synchronized state . it has the maximum value , that is @xmath169 , for the completely incoherent desynchronized state and has intermediate values between 0 and 1 for chimera states and cluster states . c. r. laing , phys . e * 92 * , 050904(r ) ( 2015 ) ; 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we show the existence of chimera - like states in two distinct groups of identical populations of globally coupled stuart - landau oscillators . the existence of chimera - like states occurs only for a small range of frequency difference between the two populations and these states disappear for an increase of mismatch between the frequencies . here the chimera - like states are characterized by the synchronized oscillations in one population and desynchronized oscillations in another population . we also find that such states observed in two distinct groups of identical populations of nonlocally coupled oscillators are different from the above case in which coexisting domains of synchronized and desynchronized oscillations are observed in one population and the second population exhibits synchronized oscillations for spatially prepared initial conditions . perturbation from such spatially prepared initial condition leads to the existence of imperfectly synchronized states . an imperfectly synchronized state represents the existence of solitary oscillators which escape from the synchronized group in population - i and synchronized oscillations in population - ii . also the existence of chimera state is independent of the increase of frequency mismatch between the populations . we also find the coexistence of different dynamical states with respect to different initial conditions which causes multistability in the globally coupled system . in the case of nonlocal coupling , the system does not show multistability except in the cluster state region .

few experiments are performed without some attempt at estimating their errors , and the random errors of measurement in radio astronomy are typically determined in one general way . some form of comparison is performed whereby samples are taken toward and away from a signal source , or with and without a spectral line . subsequent analysis proceeds under the assumption that random errors everywhere in the dataset are as given by the statistical properties manifested in the signal - free regions . no attempt is made to measure the variances of signal - bearing and signal - free samples separately during the experiment , and , after the fact , random errors of measurement in signal - bearing samples are obscured because the form of the signal is arbitrary . discussions of fitting and profile analysis invariably assume that measurement variances are the same with or without the signal , as for instance the zeeman analysis of @xcite or the fitting of functions ( @xmath0 gaussians ) by @xcite or @xcite . textbook discussions contain no suggestion that system noise is influenced by the presence of a signal or that samples with different variances may be interleaved in the same datastream @xcite . yet , such treatment has been flawed for a surprisingly long time . 100 k h i lines have been routinely observed with sub-100 k receiving systems for more than 30 years . continuum sources whose antenna temperatures exceed the equivalent noise temperature of the receiving equipment have been observed even longer . the error of measurement in signal - bearing samples is often significantly different with current receivers it could easily be a factor of 5 at the peak of a strong galactic h i emission line but the difference has been ignored . error estimates determine confidence levels and even data containing strong signals can be compromised by misunderstanding of their significance ; for instance , when two very strong signals are differenced to detect a smaller one in h i emission - absorption experiments and searches for zeeman splitting . considering how slowly experimental errors typically improve with the amount of time invested in an experiment , it follows that changes in the acknowledged errors of an experiment are equivalent to much larger differences in the observing time required to reach them . @xmath1 knowledge of errors is an important element in the design of experiments and these considerations may have a significant effect on the planning of an observing session . they should be implemented in the software which supports analysis . the purpose of this work is to illustrate a variety of common situations where random error is dominated by the presence of a signal . in the following section some basics of radio astronomy measurement are sketched . these are used to analyse the statistics of noise and the errors of component fitting when signals are present in emission and absorption . the final section is a brief summary with an even briefer mention of the extension of these notions to aperture synthesis . a temperature scale is established whereby power is compared to the classical power spectral density kt ( w hz@xmath2 ) in a resistor in thermal equilibrium at temperature t @xcite . the output power level of the telescope system is then quoted as a system temperature , @xmath3 , k. the actual power density @xmath4 @xcite reduces to kt only in the rayleigh - jeans limit and when zero - point fluctuations are ignored . in our simplified discussion we assert = + . represents everything which does not depend on any particular source or input signal and we assume that it is a constant or constant function of frequency @xmath5 : possible dependencies of are suppressed for convenience of notation . observing at a frequency @xmath5 entails a minimum contribution of @xmath6 to , which is included in @xmath7 . represents a signal external to the telescope . the equivalent temperature of a signal is its antenna temperature which by convention is related to the incident flux density s@xmath8 ( w m@xmath9 hz@xmath2 ) as s@xmath8@xmath10 k / a . the effective area a is proportional to the geometric area of the telescope aperture . the signal may be confined in space or frequency , so we write = ( v ) where v is some combination of independent variables . in the presence of signal the power density is k(v ) = k + k(v ) and the dependence of upon v makes similarly dependent . if v represents the pointing of the telescope , added power comes and goes as the telescope moves . alternatively , v may be velocity or frequency , and , as far as the receiver and square - law detector are concerned , the presence of signal at some v = v is not manifested at v @xmath11 v. the passband may be translated or inverted by mixing , but the receiver and detector electronics are entirely linear in frequency . the spectrum is not jumbled nor is it appreciably smoothed until it is integrated and channelized in the so - called backend . in sect . 2.7 we discuss an exception to this linearity , namely , quantization noise in digital correlator spectrometers . eventually a datastream is formed from samples of , each of duration t ( say ) taken over a spectral width @xmath12 ; this could be a spectrum , a continuum drift scan , _ etc . _ associated with measurement of the output power k there is a variance given by the @xcite or radiometer equation : @xmath13 the dimensionless quantity n @xmath14 is the product of the bandwidth measured in hz and the integration time in seconds . precise determination of the output power density kt within a band @xmath15 is done by averaging n independent samples . within a band of width @xmath15 about some frequency @xmath5 , the contained frequency components beat each other down to a frequency range 0 .. @xmath15 so that all appear together summed within one channel of this width . radiometer noise in the output datastream is the measurement variance of the power , independent of whether that power was contributed by or . so the variance of the measured strength of an emission line , usually considered to be set only by , actually increases in proportion to the source strength itself , weakly for weak signals and more strongly for very strong ones . as examples of the way that random error is affected by considerations of experimental design , we compare some common methods of data - taking . we consider that it is possible to take data `` on''- or `` off''-source ; if the data are spectra , even the on - source data may have regions of the bandpass which are signal - free . in the simplest case where data are taken while staring at the source , the variance is given directly by 1 @xmath16 when on- and off - source data are differenced the rms is @xmath17 and the rms in signal - free regions is increased relative to that at the signal peak . in some cases a quotient is formed from on- and off - source data : the mean off - source power level is equated to a number , @xmath7 , and data appear in the form @xmath7(on / off ) or @xmath7(on - off)/off . both have the variance @xmath18 so formation of the quotient increases the rms in the signal - bearing regions relative to the case where simple differencing is done , and everwhere relative to the pure `` on '' spectrum . because of such considerations , it is not possible to calculate the random error in signal - bearing regions , even given the empirical rms in the signal - free regions and the system properties which pertain to them , unless it is also understood how the data were taken . one obvious example of the strong signal limit of a spectral line is galactic atomic hydrogen . 1 shows a typical low latitude galactic h i profile observed with a 25 m telescope @xcite during the leiden - dwingeloo sky survey ( ldss ) . in the lower panel , the scale is expanded to show how the @xmath19 noise envelope varies for data taken in the form ( on - off)/off with @xmath20k , a typical value during the survey . the spectrum in fig . 1 still has very high peak / rms signal - noise ( 465:1 ) , but not nearly as good ( 1700:1 ) as implied by the 0.06 k rms over the baseline regions : the rms error of the integrated brightness is nearly twice as high as that estimated from the baseline rms level . h i is now commonly observed with @xmath21k . if the same profile were reobserved with = 18 k for one - fourth the amount of time ( to reach the same baseline rms ) , the line - generated rms error would be twice as high again . from the ldss , we find that some 41% of the sky contains h i with a peak brightness @xmath22k , 33% has @xmath23k and 27% has @xmath24k ( for 0@xmath25 180 , 0@xmath26 90 ) . discussions of profile fitting typically assume that the rms fluctuation is the same in every channel of a spectrum ; to do otherwise would introduce imponderables and greatly hinder general understanding . however , datapoints having a higher rms should be accorded lower weight . we did a numerical experiment , fitting pure gaussian profiles of fixed width ( fwhm=@xmath27v)and varying strength ( 0 ) , in the presence of noise which varies following 1 ( a pure `` on '' scan following the discussion of sect . we constructed spectra with 1 channels at an assumed observing frequency of 1420.40575 mhz ( the @xmath2821 cm line ) , using = 20 k typical of modern h i receivers . we assumed an observing time of 30 seconds , so that @xmath29 in 1 or @xmath27 t = 0.053 k when = 0 . we then inserted gaussian lines having @xmath30 and peak strengths ( 0 ) = 2.5 , 5.0 , 10 , 20 , ... 160 k , with the variance of the noise in accord with 1 . ensembles of such spectra were generated for each value of ( 0 ) and fit to single gaussians . the fitting was done twice for each spectrum , weighting by constant or ( correctly ) changing variance . the results of this experiment are reported in fig . the bottom curve in each panel is the rms of the fitted parameter given by analytic formulae , which coincides with the mean _ a posteriori _ error estimate returned by fitting software which assumes a constant profile rms . stronger lines lead to linear improvements in fitting of the central velocity and width in this case , while the peak and profile integral fits are independent of strength ; the fractional precision increases but fitting to the profile integral does not achieve higher precision than simply summing the channel values . the uppermost curve in each panel is the actual rms of the parameter determination with weighting by a constant variance . the shaded ( middle ) curve is the rms with proper weighting ; in this case , the fitting software returns accurate error estimates . several phenomena are discernible in this diagram . there are irremediable increases in the variances of the fitted parameters relative to the case of constant profile rms . the precision of the fitted centroid and width improve only very slowly for strong signals , instead of linearly . variances of the peak and integrated strengths increase in absolute terms as well . the fitting is only very slightly improved by correct weighting and the actual variances and the claimed error estimates diverge sharply if the behaviour of the noise is ignored . this could be misconstrued as implying that the stronger lines are less purely gaussian . staring at a continuum source characterized by an antenna temperature = results in a system temperature = + . if the continuum is extinguished by a pure scatterer characterized by optical depth @xmath31 , it follows that @xmath32 @xmath33 the system temperature is higher where there is no absorption . 4 can be inverted to solve for the optical depth from the observed profile of ( v ) , @xmath3 @xmath34 . neglecting other effects , the rms of the line / continuum ratio ( the argument of the logarithm in this expression ) is just @xmath35 . @xmath36 may be normally distributed but the logarithmic dependence of @xmath31 makes its error distribution noticeably asymmetric for moderate to large optical depth . change in the derived optical depth for a given fluctuation @xmath37 in the line / continuum ratio can be written @xmath38 where @xmath39 and @xmath40 convey the sense of the variations . differentiation yields the rms of the derived optical depth @xmath41 . \eqno(7)\ ] ] the usual analysis sets @xmath42 on the right - hand side of 5 so that the term in brackets in 7 is unity . in fig . 3 we plot @xmath43 for different , taking @xmath44 in 6 and assuming = 20 k , @xmath29 as before . in the usual analysis ( upper panel ) the fractional error in optical depth is minimized at @xmath45 for all and sensitivity appears to saturate at rather small @xmath46 . however , use of 7 shows that the sensitivity never saturates , in the sense that it is possible to achieve higher precision on ever - thicker lines ( lower panel ) . furthermore , the error in optical depth at @xmath45 is much smaller in the lower panel when @xmath47 . numerical experiments doing gaussian fitting to absorption lines showed ( as before ) that proper weighting gives slightly improved parameter variances , and much - improved error estimates . because the rms is higher in signal - free regions , naive error estimates returned by unwitting software are too large . error in determining the continuum level of the baseline regions of an absorption spectrum increases with and may eventually become the limiting factor in determining the line / continuum ratio . use of digital correlators represents a possible departure from the frequency - preserving character of the receiver and detector front - end , owing to the phenomenon of quantization noise @xcite . input to the correlator is bandpass filtered so that the sampling theorem may be applied to recovery of the data , but digitization of the continuously varying input power results in a representation of the signal which is very strongly _ not _ band - limited . that portion of the power spectrum lying outside the original band is returned , in varying degree depending on the sampling rate , as a form of noise . for nyquist sampling ( sampling at a rate twice the bandwidth ) all is returned . for faster sampling the return is reduced as sampling sidebands beat with weaker , further - out portions of the quantization noise spectrum . as shown by @xcite for a 16-level system , quantization noise is steadily reduced until the sampling rate is 10 times nyquist . thus , sampling and quantization schemes scatter input power throughout the passband . experiments using input thermal noise on systems with ( many ) more bits than are used in radio astronomy show that the quantization noise is essentially white ( _ ibid _ ) but the spectral characteristics of quantization noise are very much dependent on the form of the input . very strong , highly confined signals can produce distortions of the outlying passband . weaker signals will simply be dispersed with little effect on either the noise level or shape of the passband . because of quantization noise , even the blackest absorption line will not reduce the rms to the level attained in the absence of all input signal . 5 , modified to account for quantization loss ( 1-@xmath48 ) in the case that strong absorption occupies a negligibly small fraction of the correlator bandpass ( so that the quantization noise remains evenly distributed over the passband ) is @xmath49 examples of quantization losses at nyquist sampling rates are ( 1-@xmath48 ) = 0.36 ( 1-bit or 2-level quantization ) , 0.12 ( 3-level ) and 0.028 ( 9-level ) , so that minimum fractions @xmath50 = 0.57 , 0.14 or 0.03 of the rms corresponding to the input would unavoidably be present in each channel , including those at the bottom of the line . this complicates error analysis but the high efficiencies of modern correlators preserve at least some of the benefits discussed . such considerations are another reason to prefer higher - level quantization and over - sampling schemes . radio astronomers frequently observe signals which are strong enough to dominate the random errors of their experiments . unfortunately , it is not always possible to recognize the effects which are induced and they are neglected . nonetheless , they have always been present in the data . this discussion points up obvious deficiencies in extant data reduction software and analysis techniques . perhaps less obvious is the need not only for accurate calibration but also for reliable reporting on the part of the telescope systems . measurement errors can not be accurately assessed and accomodated in downstream data handling unless the system , continuum and line antenna temperatures are preserved , along with knowledge of the mode of data - taking . synthesis instruments may be particularly difficult in this regard . consider the use of the vla ( say ) to detect h i absorption against a continuum source at low galactic latitude in the presence of an emission profile like that shown in fig . 1 . the vla does not return the total power or singledish spectra , or , equivalently , the variation of across the passband . the interferometer experiment _ per se _ can only succeed to the extent that foreground emission disappears ; only its added noise contribution remains . we began the discussion by pointing out that the noise contributed from sky signals in single - dish observations occurs ignoring sidelobes , quantization noise and the like at those places and/or frequencies where the sources themselves are located . it is an interesting endeavour to try to understand the extent to which source noise in interferometer experiments is similarly localized in the output datastream . for phased arrays it would seem possible to reproduce the single - dish mode . for synthesis arrays @xcite the situation is much more complicated and uncertain even in the weak signal limit . the national radio astronomy observatory is operated by aui , inc . under a cooperative agreement with the us national science foundation . i thank darrel emerson , tony kerr , robert lucas and a. r. ( dick ) thompson for helpful comments . barry clark pointed out the relevance of quantization noise and fred schwab provided the reference to @xcite . this paper was put in final form while the author was enjoying the hospitality of the iap in paris .

the random error of radioastronomical measurements is usually computed in the weak - signal limit , which assumes that the system temperature is sensibly the same on and off source , or with and without a spectral line . this assumption is often very poor . we give examples of common situations in which it is important to distinguish the system noise in signal - bearing and signal - free regions .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Passenger Vessel Safety Act of 1993''. SEC. 2. PASSENGER. Section 2101(21) of title 46, United States Code, is amended to read as follows: ``(21) `passenger'-- ``(A) means an individual carried on the vessel except-- ``(i) the owner or an individual representative of the owner or, in the case of a vessel under charter, an individual charterer or individual representative of the charterer; ``(ii) the master; or ``(iii) a member of the crew engaged in the business of the vessel who has not contributed consideration for carriage and who is paid for on board services. ``(B) on an offshore supply vessel, means an individual carried on the vessel except-- ``(i) an individual included in clause (i), (ii), or (iii) of subparagraph (A) of this paragraph; ``(ii) an employee of the owner, or of a subcontractor to the owner, engaged in the business of the owner; ``(iii) an employee of the charterer, or of a subcontractor to the charterer, engaged in the business of the charterer; or ``(iv) an individual employed in a phase of exploration, exploitation, or production of offshore mineral or energy resources served by the vessel. ``(C) on a fishing vessel, fish processing vessel, or fish tender vessel, means an individual carried on the vessel except-- ``(i) an individual included in clause (i), (ii), or (iii) of subparagraph (A) of this paragraph; ``(ii) a managing operator; ``(iii) an employee of the owner, or of a subcontractor to the owner, engaged in the business of the owner; or ``(iv) an employee of the charterer, or of a subcontractor to the charterer, engaged in the business of the charterer. ``(D) on a sailing school vessel, means an individual carried on the vessel except-- ``(i) an individual included in clause (i), (ii), or (iii) of subparagraph (A) of this paragraph; ``(ii) an employee of the owner of the vessel engaged in the business of the owner, except when the vessel is operating under a demise charter; ``(iii) an employee of the demise charterer of the vessel engaged in the business of the demise charterer; or ``(iv) a sailing school instructor or sailing school student.''. SEC. 3. PASSENGER VESSEL. Section 2101(22) of title 46, United States Code, is amended to read as follows: ``(22) `passenger vessel' means a vessel of at least 100 gross tons-- ``(A) carrying more than 12 passengers, including at least one passenger for hire; ``(B) that is chartered and carrying more than 12 passengers; or ``(C) that is a submersible vessel carrying at least one passenger for hire.''. SEC. 4. SMALL PASSENGER VESSEL. Section 2101(35) of title 46, United States Code, is amended to read as follows: ``(35) `small passenger vessel' means a vessel of less than 100 gross tons-- ``(A) carrying more than 6 passengers, including at least one passenger for hire; ``(B) that is chartered with the crew provided or specified by the owner or the owner's representative and carrying more than 6 passengers; ``(C) that is chartered with no crew provided or specified by the owner or the owner's representative and carrying more than 12 passengers; or ``(D) that is a submersible vessel carrying at least one passenger for hire.''. SEC. 5. UNINSPECTED PASSENGER VESSEL. Section 2101(42) of title 46, United States Code, is amended to read as follows: ``(42) `uninspected passenger vessel' means an uninspected vessel-- ``(A) of at least 100 gross tons-- ``(i) carrying not more than 12 passengers, including at least one passenger for hire; or ``(ii) that is chartered with the crew provided or specified by the owner or the owner's representative and carrying not more than 12 passengers; and ``(B) of less than 100 gross tons-- ``(i) carrying not more than 6 passengers, including at least one passenger for hire; or ``(ii) that is chartered with the crew provided or specified by the owner or the owner's representative and carrying not more than 6 passengers.''. SEC. 6. PASSENGER FOR HIRE. Section 2101 of title 46, United States Code, is amended by inserting between paragraphs (21) and (22) a new paragraph (21a) to read as follows: ``(21a) `passenger for hire' means a passenger for whom consideration is contribution as a condition of carriage on the vessel, whether directly or indirectly flowing to the owner, charterer, operator, agent, or any other person having an interest in the vessel.''. SEC. 7. CONSIDERATION. Section 2101 of title 46, United States Code, is amended by inserting between paragraphs (5) and (6) a new paragraph (5a) to read as follows: ``(5a) `consideration' means an economic benefit, inducement, right, or profit including pecuniary payment accruing to an individual, person, or entity, but not including a voluntary sharing of the actual expenses of the voyage, by monetary contribution or donation of fuel, food, beverage, or other supplies.''. SEC. 8. OFFSHORE SUPPLY VESSEL. Section 2101(19) of title 46, United States Code, is amended by inserting ``individuals in addition to the crew,'' immediately after ``supplies,'' and by striking everything after ``resources'' to the period at the end. SEC. 9. SAILING SCHOOL VESSEL. Section 2101(30) of title 46, United States Code, is amended in subparagraph (B) by striking ``at least 6'' and substituting ``more than 6''. SEC. 10. SUBMERSIBLE VESSEL. Section 2101 of title 46, United States Code, is amended by inserting between paragraphs (37) and (38) a new paragraph (37a) to read as follows: ``(37a) `submersible vessel' means a vessel that is capable of operating below the surface of the water.''. SEC. 11. GENERAL PROVISION. (a) Section 2113 of title 46, United States Code, is amended to read as follows: ``Sec. 2113. Authority to exempt certain vessels ``If the Secretary decides that the application of a provision of part B, C, F, or G of this subtitle is not necessary in performing the mission of the vessel engaged in excursions or an oceanographic research vessel, or not necessary for the safe operation of certain vessels carrying passengers, the Secretary by regulation may-- ``(1) for an excursion vessel, issue a special permit specifying the conditions of operation and equipment; ``(2) exempt an oceanographic research vessel from that provision under conditions the Secretary may specify; and ``(3) establish different operating and equipment requirements for vessels defined in section 2101(42)(A) of this title.''. (b) Section 4105 of title 46, United States Code, is amended-- (1) by inserting ``(a)'' before the text; and (2) by adding a new subsection (b) to read as follows: ``(b) Within twenty-four months of the date of enactment of this subsection, the Secretary shall, by regulation, require certain additional equipment which may include liferafts or other lifesaving equipment, construction standards, or specify additional operating standards for those uninspected passenger vessels defined in section 2101(42)(A) of this title.''. SEC. 12. EFFECTIVE DATE. (a) Regulations governing small passenger vessels and passenger vessels, as those terms are defined in 46 U.S.C. 2101, which are chartered with no crew provided shall not apply before May 1, 1994. (b) The Secretary of the Department in which the Coast Guard is operating may extend the time period for compliance with the regulations referenced in subsection (a) for an initial period of up to one year and may extend the period of compliance for one additional period of up to one year if the owner of the vessel demonstrates to the satisfaction of the Secretary that a good faith effort, with due diligence and care, has failed to enable compliance with the deadline under subsection (a). SEC. 13. SENSE OF CONGRESS REGARDING USE OF VESSELS CONSTRUCTED IN UNITED STATES FOR CARRYING PASSENGERS FOR HIRE. It is the sense of the Congress that persons who, for the purpose of carrying passengers for hire in the United States, operate or charter vessels with respect to which this Act (including the amendments made by this Act) applies should only operate and charter for that purpose vessels constructed in the United States. Passed the House of Representatives June 9, 1993. Attest: DONNALD K. ANDERSON, Clerk.

Passenger Vessel Safety Act of 1993 - Amends Federal marine safety law to revise certain definitions regarding passengers, passenger vessels, and certain other types of vessels (including offshore supply, sailing school, and submersible vessels). Authorizes the Secretary of the Department in which the Coast Guard is operating to exempt certain excursion, oceanographic research, and other vessels carrying passengers from certain marine safety laws. Authorizes the Secretary to establish different operating and equipment requirements for such vessels. Requires the Secretary to issue regulations for uninspected passenger vessels: (1) requiring certain additional equipment (including liferafts or other lifesaving equipment) and construction standards; or (2) specifying additional operating standards. Authorizes the Secretary to extend for one year (renewable for another year) the time period for small passenger vessels and passenger vessels chartered with no crew provided to comply with such marine safety requirements, if the owner of such a vessel can demonstrate a good faith effort to comply with such requirements. Expresses the sense of the Congress that operators of passenger vessels should use only U.S.-made vessels.

a 42-year - old female smoker presented to the vascular department with a 10-day history of acute - onset right leg pain . her vascular history was significant for stable intermittent claudication in the left leg that had been ongoing for several years and a right great hallux ulcer secondary to trauma that necessitated multiple courses of antibiotics . on examination , the first and second digits of her right foot were noted to be discoloured , with associated decreased sensation in the affected areas . no femoral or lower extremity distal pulses were palpable . a discernible aortic , renal , and iliac bruit were noted . a crossed - fused ectopic kidney was noted in the right upper pelvis ( figs . the ectopic kidney was supplied by two renal arteries , one arising from the right renal artery and supplying the upper pole at the l2 vertebral level and another right renal artery supplying the midpole at the l4 vertebral level . the arterial supply of the left kidney was an artery arising from the mid - line just above the abdominal aorta . two renal veins were noted , merging into a common origin with the inferior vena cavae . the operation was performed under a general anaesthetic as well as a t10- to t11 vertebral level epidural . a midline laparotomy was performed with exposure of the suprarenal aorta following left medial visceral rotation . urology input was requested to identify the left ureter for the purpose of graft tunnelling . a proximal end - to - side anastomosis with a 126-mm dacron graft was performed with 4 - 0 prolene , and the graft was tunnelled retroperitoneally , posterior to the ureters bilaterally . distally , bilateral common femoral artery exposure was performed and an end - to - side anastomosis with 6 - 0 prolene was carried out . the patient spent two days in the intensive care unit and was discharged on the second postoperative day to the ward . on the third postoperative day , she complained of left leg numbness and pain . she was noted to have a palpable left femoral pulse but no distal pedal pulses present on the left side . an ultrasound showed a left common femoral artery occlusion distal to the left limb of the aortobifemoral bypass graft . the patient had an uneventful postoperative course and was discharged from the hospital four days later . the earliest description of renal ectopia in the presence of abdominal aortic aneurysmal disease was by julian in 1956 . renal fusion and ectopia , while rare , are the most common congenital abnormalities of the kidneys . 2 . renal ectopia arises from the aberrant ascent of the kidneys during embryological development in the fourth to eighth weeks of gestation . this can be a result of anomalies of the ureteric metanephros , vascular supply , or genetic abnormalities . as the kidneys ascend , they derive their vascular supply from the vessels closest to them ; initially the median sacral artery , then the common iliac and inferior mesenteric arteries , and finally the aorta . upon reaching the normal retroperitoneal location in the body , renal arteries and veins develop to provide vascular support . in renal ectopia , aberrant vasculature arises because the ectopic kidneys maintain their associated multiple arterial branches as they ascend , which is a reflection of the embryological origin of the blood supply to the kidneys during normal development . the sites of ectopia are varied and include the pelvic , iliolumbar , and lower chest regions . crossed renal ectopia is the second most common renal fusion anomaly after horseshoe kidney , with an incidence of 1 in 1,000 . four types exist : type a , crossed renal ectopia with fusion ; type b , crossed ectopia without fusion ; type c , solitary crossed ectopia ; and type d , bilaterally crossed ectopia . in patients with crossed renal ectopia , the arterial blood supply to the kidneys may range from one to six arteries that are often abnormally located , with 75% arising from the upper aorta and 25% arising from the lower aorta and iliac arteries . venous return may also be abnormal , with the majority of return via the main right and left renal veins draining directly into the inferior vena cava . crossed ectopia is always associated with abnormally located ureters . regardless of whether one or more kidneys are involved , the associated ureters always cross the midline at the level of the distal aorta or bifurcation and enter the bladder on the side of embryonic origin . generally , renal fusion and ectopia are relatively benign conditions , associated with normal renal function in adulthood . the problem arises when the same patient presents for the surgical management of aorto - occlusive disease . this requires preoperative imaging to elucidate the vascular and renal anatomy , planning the optimal surgical exposure of the aortic lesion , identifying the corresponding obstructed arterial branch , and preserving the renal blood supply with avoidance of injury to the abnormally positioned ureters . of particular importance is the preservation of the renal blood supply , as all renal and accessory arteries are end arteries with no anastomoses for alternative supply if sacrificed , and renal failure is common in the postoperative period in patients with crossed renal ectopia . no fixed recommendations currently exist regarding the surgical approach in the treatment of aorto - occlusive disease in this subgroup of patients . the majority of the literature discusses aortic aneurysmal disease in conjunction with renal ectopia . in these studies , the largest case series on this particular subset of patients was performed by crawford et al . in 1988 , in which 17 patients with ectopic kidneys and concomitant aorto - occlusive or aneurysmal disease were studied . the surgical approach was retroperitoneal with exposure of the aneurysm from behind and reflection of the kidney mass and ureter upwards and to the right in one case , while the other case involved a standard anterior midline incision . studied the technical challenges and outcomes of 18 patients with renal anomalies and concurrent aortic pathology . the choice of surgical approach was determined through the pre - operative evaluation of the vascular anatomy . the anterior transperitoneal approach was utilized in 16 patients and a retroperitoneal / thoracoabdominal approach in the remaining two , of which one was an ectopic kidney . the perioperative mortality rate was 0% , with no renal or aortic complications at long - term follow - up . in our case , the patient had type a crossed renal ectopia . a midline anterior approach was performed , with the utilisation of left medial visceral rotation . this technique is also known as the cattell - mattox procedure and involves the mobilisation of the left colon , spleen , and kidney to expose the entire length of the abdominal aorta ( fig . conversely , right medial visceral rotation is known as the cattell - braasch procedure , which normally involves an extended kocher incision to allow for mobilisation of the duodenum as well . we opted for this technique to allow for optimal visualisation of the vascular and renal anatomy and to facilitate operative intervention . in summary , renal anomalies in the presence of aortic disease do not preclude aortic surgery , although careful preparation must be done before operative intervention . there are two main aims of surgery : revascularisation to ameliorate the effects of aorto - occlusive disease and the preservation of renal function . the approach to patients with crossed renal ectopia and concomitant aorto - occlusive disease should thus be stepwise and structured , involving the following steps . ( 1 ) careful elucidation of the vascular and renal anatomy , with consideration of computerized tomography , angiography , and intravenous pyelography . ( 2 ) early consultation with urology for planning the surgical management of aberrant renal vasculature in conjunction with revascularisation . ( 3 ) the surgical approach should be based on the vascular and renal anatomy , with the majority of studies advocating a midline anterior transperitoneal approach . this approach allows for the optimal visualization of the aberrant ectopic renal vasculature and also facilitates operative intervention . ( 4 ) the preservation of the renal vessel and ureter supply is of paramount importance . surgeons should be aware of the crossing of the ureters at the midline of the distal aorta or bifurcation , regardless of the type of ectopia .

we present a rare case of a patient with aortoiliac occlusive disease on the background of type a crossed renal ectopia , for whom open surgical intervention was required . aortic exposure in patients with concomitant crossed renal ectopia can present technical challenges to the vascular surgeon . the knowledge of variations in the ectopic renal blood supply is of paramount importance when performing surgery to treat this condition and affects the choice of surgical exposure . we present and discuss the operative details of our patient and outline an approach to this subset of patients .

the top quark may be a window to physics beyond the standard model ( sm ) . its mass near the electroweak scale and its large coupling to the higgs boson may be crucial to understanding the electroweak sector beyond the sm . now that the sm - like higgs boson has been observed at the large hadron collider ( lhc ) @xcite with a relatively light mass of about 125 gev , the assumed `` naturalness '' of the higgs sector @xcite suggests the existence of a partner of the top quark below or near the tev scale , motivating theories such as weak - scale supersymmetry , little higgs , and extra dimensions ( either warped or universal ) . vacuum stability of the electroweak potential also indicates the need for new physics to balance the large top - quark contribution . the top quark hence provides a possible early indicator of new physics and a good probe of a wide variety of new - physics scenarios . the lhc is a top factory , producing a hundred times more @xmath4 pairs from qcd processes than were produced at the tevatron . top - quark production is well understood in the sm . thus any new physics contributions will be on top of a well - known and well - measured , albeit large , background . with the discovery era ushered in by the lhc , it would be prudent to keep the initial search as general as possible . in this work , we take a model - independent approach to searching for new physics processes of the form @xmath5 where @xmath6 is a massive new particle with the same gauge quantum numbers as the top quark and @xmath7 is an electrically and color neutral stable particle . the weakly interacting @xmath7 could be a constituent of dark matter , which would manifest itself as missing energy in a collider detector . we systematically consider different spin configurations ( 0 , 1/2 , and 1 ) for the new particles @xmath6 and @xmath7 . each combination is exemplified by particles in well - motivated new - physics models ( see the next section for details ) . for example , in the minimal supersymmetric standard model ( mssm ) @xmath6 could be a scalar top and @xmath7 the lightest neutralino . this case has been studied extensively in the literature ( see , for example , refs . however , we do not limit ourselves to specific particles in a particular model ; rather , we undertake a general categorization , assuming merely a mass accessible at the lhc and a discrete symmetry that ensures the stability of @xmath7 . for simplicity , we restrict consideration to processes that involve only the top partner , @xmath6 , and the dark - matter candidate , @xmath7 , as new particles . in order to distinguish experimentally between the different possibilities , one needs to determine the spins and couplings of the new particles @xmath6 and @xmath7 . in this paper , several observables for this purpose are proposed and their usefulness is demonstrated in a realistic monte carlo simulation . to avoid ambiguities due to model - dependent branching fractions , we do not consider the total cross section in this set of variables . the paper is organized as follows . in section [ setup ] we introduce the model - independent classification of new - physics top partners and their interactions . the production of these particles at the lhc is discussed in section [ channels ] , while the current bounds from collider searches are summarized in section [ bounds ] . in section [ sigsel ] , the expected reach of the lhc for this class of processes is analyzed through a detailed monte carlo simulation . the determination of relevant properties of the new particles , such as mass , spin and couplings , and the discrimination between models are discussed in section [ props ] . finally , conclusions are presented in section [ concl ] . colored particles can be copiously produced at the lhc by strong qcd interactions . let @xmath6 denote a new color - triplet particle with charge + 2/3 . @xmath6 and its antiparticle can be produced at leading order in qcd by the processes shown in fig . [ fig : prodxy ] ( left ) . we shall not consider the production of a single new particle via yukawa - type interactions : since they are strongly model - dependent and are subject to strong constraints from flavor physics , it is assumed that such vertices are forbidden by a discrete symmetry . @xmath6 decays to a new particle that is a color singlet , denoted @xmath7 [ see fig . [ fig : prodxy ] ( right ) ] , which will show as missing energy in a collider experiment . ' '' '' [ fig : prodxy ] there are four possible combinations of spins that allow a coupling between @xmath7 , @xmath6 and the sm top quark , @xmath8 . these are listed , with the relevant couplings and sample model decays , in table [ tab : models1 ] . for fermions we allow a general chirality structure . we shall henceforth refer to these scenarios as models i , ii , iii , and iv . ._quantum numbers and couplings of the new particles @xmath7 and @xmath6 , which interact with the sm top quark , @xmath8 . in the last column , @xmath9 and @xmath10 are the scalar top and lightest neutralino in the mssm , respectively @xcite . @xmath11 , @xmath12 , and @xmath13 are the first - level kaluza - klein excitations of the top , the photon , and an extra - dimensional component of a photon , respectively , in universal extra dimensions ( ued ) @xcite . finally , @xmath14 is the vector superpartner in a supersymmetric model with an extended gauge sector @xcite . _ [ cols="<,^,^,^,^ , < , < " , ] the numbers refer to the purely statistical significance . however , at this level of precision , systematic errors may be important . a potentially large systematic effect stems from the uncertainty of the new - particle masses , @xmath15 and @xmath16 . while the mass difference @xmath17 can be determined rather precisely , the overall mass scale can be measured with only 2030% accuracy ; see section [ masses ] . we have estimated the effect of this uncertainty by comparing two event samples with @xmath18 and @xmath19 , which differ in @xmath15 by roughly 30% . we have found that this mass uncertainty reduces the statistical significance of the spin discrimination by about 20% ; the values of @xmath20 that account for this systematic error are about 50% greater than those quoted above . in conclusion , the determination of the spin of the top partner , @xmath6 , is possible with very moderate amounts of data . on the other hand , the distinction between models ii and iii , which both have a fermionic @xmath6 but differ in the spin of the singlet @xmath7 , is much more difficult . after surveying more than a dozen different kinematic variables based on the top - quark momenta , we found no significant difference between scenarios ii and iii for any of them . this finding agrees with the results of ref . @xcite . however , more information can be obtained from observables that are sensitive to the top - quark polarization , as will be discussed next . the chirality structure of the decay @xmath22 ( that is , the relative contributions of left- and right - handed chiral couplings ) leaves an imprint on the polarization of the top quark , which can be analyzed through angular distributions of the top - quark decay products . this method is particularly effective when the mass difference between @xmath6 and @xmath7 is large ( @xmath23 ) , so that the top quark is energetic and therefore the helicity is preserved , reflecting the chirality . for instance , one can look at the angle @xmath24 ( @xmath25 ) of the @xmath26 quark ( lepton ) with respect to the top - quark boost direction in the top rest frame . because the @xmath26 quark is always left - handed , it is emitted predominantly in the forward direction ( @xmath27 ) if the top quark is left - handed , but mostly in the backward direction ( @xmath28 ) if the top quark is right - handed . in practice , even if the top quark is produced fully polarized in the decay @xmath29 , some of the polarization is washed out by the mass of the top , but the @xmath28 distribution will still exhibit a characteristic difference between left- and right - handed @xmath30 couplings . in the following , we shall illustrate this behavior using a parton - level simulation with calchep . we shall focus on the leptonically decaying top quark , since it has a cleaner final state . the top - quark rest frame can not be reconstructed because of the unobserved neutrino momentum , so we analyze the angular distribution in the rest frame of the visible @xmath31 system instead . the results are shown in fig . [ fig : pol ] . ( -2,4)model i(-2,4)model ii + ( -2,5)model iii(-2,5)model iv as fig . [ fig : pol ] shows , the distribution is skewed to smaller values of @xmath32 or , equivalently , larger values of @xmath33 in the case of a left - handed @xmath30 coupling ( black curves ) than in the right - handed case ( red curves ) . for a mixed case with non - zero left- and right - handed components , one obtains a distribution that lies between the black and red curves this qualitative behavior is the same for all four spin combinations in table [ tab : models1 ] , although they differ from each other in the detailed shape of the distribution . in particular , cases ii and iii have distinctly different shapes ; hence , the analysis of this observable may allow one to determine not only the chirality of the @xmath30 coupling but also the spin of the @xmath7 particle . such a determination is not possible with observables that treat the top quarks as basic objects . furthermore , one can probe the chirality even with limited statistics by using two bins and forming the asymmetry @xmath34 from fig . [ fig : pol ] , one can see that when @xmath35 is about @xmath36 @xmath37 will be most sensitive to the chirality of the coupling . table [ tab : topasym ] shows the asymmetry @xmath38 for models i iv with two choices of the masses @xmath15 and @xmath16 . the usefulness of @xmath38 for the determination of the coupling is enhanced by its relative insensitivity to the spin and mass combinations . .85|c|cccc|cccc| & & + & & + @xmath39 , @xmath40 & i & ii & iii & iv & i & ii & iii & iv + 1 , 0 & @xmath410.10 & 0.02 & @xmath410.10 & @xmath410.03 & 0 & 0.15 & 0.04 & 0.10 + 0 , 1 & 0.68 & 0.55 & 0.68 & 0.61 & 0.54 & 0.39 & 0.50 & 0.45 + 1 , 1 & 0.29 & 0.28 & 0.29 & 0.29 & 0.28 & 0.27 & 0.28 & 0.27 + [ tab : topasym ] the sm - like higgs boson has been observed at the lhc with a relatively light mass of about 125 gev . the `` naturalness '' argument of the higgs sector suggests the existence of partners of the sm particles , especially the heavy top quark . the top quark may thus hold the key to new physics associated with the electroweak symmetry - breaking sector , because of its enhanced coupling to the higgs sector . in this paper , we have systematically categorized the generic interactions of a new particle that couples to the top quark and a stable neutral particle , which serves as a candidate for cold dark matter . we have considered all possible assignments of spin 0 , @xmath42 and 1 for either of the two new particles . in the search for new physics involving top quarks and its partners at the lhc , the experimental signatures may be distinctive , but challenging to disentangle . pair production of the massive top partners leads to a signature of a @xmath43 pair plus missing energy , which is difficult to separate from the large sm @xmath43 background . we have presented a set of optimized selection cuts for isolating this new physics signal at the 8 and 14 tev runs of the lhc . we have found that , at 14 tev with an integrated luminosity of 100 fb@xmath0 , a spin - zero top partner can be observed at the 5@xmath1 level up to a mass of 675 gev , while for a spin-@xmath42 top partner the reach extends to 945 gev . if a process of this type is discovered at the lhc , it will be imperative to determine the spins and couplings of the new particles , in order to understand the underlying physics mechanism . we have proposed a strategy to extract these properties from experimental data by means of suitable differential distributions of the final - state products . with this approach , a spin-0 top partner with mass of about 300 gev can be discriminated from spin-@xmath42 and spin-1 particles at the 5@xmath1 level with a luminosity of 10 fb@xmath0 at 14 tev . furthermore , the structure of the coupling that mediates the decay of the top partner into a top quark and a massive neutral particle can be analyzed by measurement of the polarization of the final - state top quarks . this method allows one to distinguish clearly between left - handed , right - handed , and vector couplings . most importantly , the proposed observables for spin and coupling determination are insensitive to unknown branching fractions and depend only mildly on the masses of the new particles . in conclusion , the lhc will allow us to observe and study top partners with mass up to about 1 tev . this program will shed light on the interplay of the higgs - boson and top - quark sectors and may elucidate the concept of naturalness . we are grateful to m. cacciari and a. kardos for providing background cross sections at 8 tev . we also thank n. christensen for help with calchep and r. mahbubani for correspondence . this project was supported in part by the national science foundation under grant phy-0854782 , by the us department of energy under grant no . de - fg02 - 12er41832 , and by pitt pacc . y.c was supported in part by the george e. and majorie s. pake fellowship . finally , t.h . is grateful for the hospitality and support of the aspen center for physics and the center for theoretical underground physics and related areas ( cetup * ) during the completion of this work . g. f. giudice , in `` perspectives on lhc physics , '' eds . g. kane , a. pierce , 155178 [ arxiv:0801.2562 [ hep - ph ] ] . p. meade and m. reece , phys . d * 74 * , 015010 ( 2006 ) . t. han , r. mahbubani , d. g. e. walker and l .- t . wang , jhep * 0905 * , 117 ( 2009 ) . t. plehn , m. spannowsky , m. takeuchi and d. zerwas , jhep * 1010 * , 078 ( 2010 ) ; + t. plehn , m. spannowsky and m. takeuchi , jhep * 1105 * , 135 ( 2011 ) . y. bai , h .- c . cheng , j. gallicchio and j. gu , arxiv:1203.4813 [ hep - ph ] ; + d. s. m. alves , m. r. buckley , p. j. fox , j. d. lykken and c. -t . yu , arxiv:1205.5805 [ hep - ph ] ; + z. han , a. katz , d. krohn and m. reece , arxiv:1205.5808 [ hep - ph ] ; + d. e. kaplan , k. rehermann and d. stolarski , arxiv:1205.5816 [ hep - ph ] . t. plehn , m. spannowsky and m. takeuchi , arxiv:1205.2696 [ hep - ph ] . j. cao , c. han , l. wu , j. m. yang and y. zhang , arxiv:1206.3865 [ hep - ph ] . b. dutta , t. kamon , n. kolev , k. sinha and k. wang , arxiv:1207.1873 [ hep - ph ] . see , for example , s. p. martin , in `` perspectives on supersymmetry ii , '' ed . g. l. kane , world scientific , singapore ( 2010 ) , 1153 [ hep - ph/9709356 ] . t. appelquist , h. c. cheng and b. a. dobrescu , phys . d * 64 * , 035002 ( 2001 ) ; + b. a. dobrescu and e. pontn , jhep * 0403 * , 071 ( 2004 ) ; + g. burdman , b. a. dobrescu and e. pontn , jhep * 0602 * , 033 ( 2006 ) . h. cai , h .- c . cheng and j. terning , phys . * 101 * , 171805 ( 2008 ) . j. pumplin , d. r. stump , j. huston , h. l. lai , p. m. nadolsky and w. k. tung , jhep * 0207 * , 012 ( 2002 ) . w. beenakker , s. brensing , m. krmer , a. kulesza , e. laenen and i. niessen , jhep * 1008 * , 098 ( 2010 ) . m. cacciari , m. czakon , m. l. mangano , a. mitov and p. nason , phys . lett . b * 710 * , 612 ( 2012 ) . t. aaltonen _ et al . _ [ cdf collaboration ] , phys . rev . lett . * 106 * , 191801 ( 2011 ) . v. m. abazov _ et al . _ [ d0 collaboration ] , phys . lett . b * 693 * , 95 ( 2010 ) ; + m. s. carena , j. hubisz , m. perelstein and p. verdier , phys . d * 75 * , 091701 ( 2007 ) . g. aad _ et al . _ [ atlas collaboration ] , phys . lett . * 108 * , 041805 ( 2012 ) . g. aad _ et al . _ [ atlas collaboration ] , atlas - conf-2012 - 071 ; + g. aad _ et al . _ [ atlas collaboration ] , atlas - conf-2012 - 073 ; + g. aad _ et al . _ [ atlas collaboration ] , atlas - conf-2012 - 074 . s. sharma [ for the cms collaboration ] , talk at the 36th international conference for high energy physics ( ichep 2012 ) , melbourne , australia , 411 july 2012 ; + c. rogan [ for the cms collaboration ] , talk at the 36th international conference for high energy physics ( ichep 2012 ) , melbourne , australia , 411 july 2012 . r. essig , e. izaguirre , j. kaplan and j. g. wacker , jhep * 1201 * , 074 ( 2012 ) ; + y. kats , p. meade , m. reece and d. shih , jhep * 1202 * , 115 ( 2012 ) ; + m. papucci , j. t. ruderman and a. weiler , arxiv:1110.6926 [ hep - ph ] ; + x .- j . bi , q .- s . yan and p .- f . yin , phys . d * 85 * , 035005 ( 2012 ) ; + c. brust , a. katz , s. lawrence and r. sundrum , jhep * 1203 * , 103 ( 2012 ) ; + n. desai and b. mukhopadhyaya , jhep * 1205 * , 057 ( 2012 ) ; + a. choudhury and a. datta , arxiv:1207.1846 [ hep - ph ] . a. lazopoulos , t. mcelmurry , k. melnikov and f. petriello , phys . b * 666 * , 62 ( 2008 ) ; + a. kardos , z. trocsanyi and c. papadopoulos , phys . d * 85 * , 054015 ( 2012 ) ; + m. v. garzelli , a. kardos , c. g. papadopoulos and z. trocsanyi , phys . d * 85 * , 074022 ( 2012 ) . m. beneke , p. falgari , s. klein and c. schwinn , nucl . phys . * b855 * , 695 ( 2012 ) . g. aad _ et al . _ [ atlas collaboration ] , arxiv:1205.2067 [ hep - ex ] . a. pukhov , hep - ph/0412191 ; + a. pukhov , a. belyaev , n. christensen , http://theory.sinp.msu.ru/~pukhov/calchep.html . t. sjstrand , s. mrenna and p. z. skands , jhep * 0605 * , 026 ( 2006 ) . c. g. lester and d. j. summers , phys . b * 463 * , 99 ( 1999 ) . for an overview , see + sect . 4 in a. j. barr and c. g. lester , j. phys . g * 37 * , 123001 ( 2010 ) , and refs . therein ; 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the top quark may hold the key to new physics associated with the electroweak symmetry - breaking sector , given its large mass and enhanced coupling to the higgs sector . we systematically categorize generic interactions of a new particle that couples to the top quark and a neutral particle , which is assumed to be heavy and stable , thus serving as a candidate for cold dark matter . the experimental signatures for new physics involving top quarks and its partners at the large hadron collider ( lhc ) may be distinctive , yet challenging to disentangle . we optimize the search strategy at the lhc for the decay of the new particle to a top quark plus missing energy and propose the study of its properties , such as its spin and couplings . we find that , at 14 tev with an integrated luminosity of 100 fb@xmath0 , a spin - zero top partner can be observed at the 5@xmath1 level for a mass of 675 gev . a spin - zero particle can be differentiated from spin-1/2 and spin-1 particles at the 5@xmath1 level with a luminosity of 10 fb@xmath0 . pitt - pacc-1208 + cetup*-12/001 chien - yi chen@xmath2 , ayres freitas@xmath3 , tao han@xmath3 , and keith s. m. lee@xmath3 _ @xmath2 department of physics , carnegie mellon university , pittsburgh , pa + _ @xmath3 pittsburgh particle physics , astrophysics , and cosmology center ( pitt pacc ) , + department of physics & astronomy , university of pittsburgh , pittsburgh , pa _ _

At the Grammy Awards, a singer was strolling down the the red carpet when a young woman ran up to her, begging for entry into her Group. She belongs to a secret, exclusive group of Los Angeles movers and shakers mostly between the ages of 19 and 35. No one except the 1,730 female members know exactly what happens inside. They can’t even reveal its name; outsiders refer to it simply as “The Girls Group.” But non-members know enough to know they want to be part of it, said Annaliese Nielsen, the founder: “It’s definitely part of Los Angeles lore.” All day long - “every time you pee, when your boss isn’t paying attention,” said Nielsen, who is 31 and also started social networking sites Crushee (to find your virtual BFF) and GodsGirls (a softcore porn site where alt glamour models network) - the women post on the group’s wall about their diseases, their hookups, their bosses. The members span every industry, and if one needs a job, the other will find her one. If one needs a boyfriend, the girls will post pictures of their single, bachelor friends for her taking. Recently, they teamed up to replace the belongings of a member whose house burnt down and paid rent for someone in a cash flow dilemma. One member, with connections to the music industry, arranged for another’s little brother to propose to his girlfriend onstage at a Foo Fighters concert. When one posted about a man who sexually assaulted her, the others destroyed his reputation and social standing. “I think it is more important than any group I was in in school or any group I’ve been in since,” said Remy Holwick, a 33-year-old photographer who splits her time between New York City and L.A. “I don’t know how I would function without that big of network that I can just cast a net to and ask a question…It’s become really integral in my day to day life.” With these benefits, it’s no wonder women go to lengths to secure the elusive membership. “You have to get real, actual people to vouch for you, and if one person vouches against you it’s just not happening,” said Nielsen. “It’s definitely a members club.” Except it all happens in the virtual realm of Facebook. Across Facebook exclusive groups like this one are forming. They don’t show up in search, and they can’t be accessed by non-invitees. Some have themes. “Lolo’s Logic,’ a group of 100 women ranging in age from early 20s to late 40s, focuses on sex. “There is nothing, and I mean nothing off limits,” said Loretta Buegeler, the 42-year-old founder who works as a mortgage processor in Glendale, Arizona. “Some of the discussions make me blush…when you see their public profile, they are June Cleavers, but in there they are little freaks!” At Christmas the members sent each other sex toys in the mail. Everyone then posted pictures of their new dildos. ||||| To gain entry into the most exclusive club in Los Angeles, there is no need to wear a trendy outfit or to slip the bouncer a Benjamin. In fact, there isn’t even a line. Instead, admission requires the approval of a scrupulous jury of 1,500 women. And if those women decide to let you into their secret club, a Facebook group called ‘Girls Night In,’ all 1,500 of them will become your very best friends. ‘Girls Night In’—or GNI, as its members call it—is like a giant online slumber party, one that never ends, slips into your pocket and can be called upon at any moment in the day that you need it. It is a constant stream of brutally frank chatter about relationships, work, sex, race, gender and, yes, cats, along with a bizarrely large quantity of nude selfies. It is made up mainly of women in their 20s and 30s who live in the Los Angeles area. Among its ranks are Instagram-famous models, former reality show contestants, celebrity makeup artists and the quasi-famous girlfriend of a very famous singer. Lest you be confused (or hope to try to join it), you should know that it’s not actually called ‘Girls Night In,’ but rather changes names constantly based on a rotating series of inside jokes. Getting in requires recommendations from at least three women already in the group. “If you meet a nice girl in a bathroom while you are drunk i am really happy for you and for her but that’s not cause to add her to this group,” its rules advise. The rules of membership read even stricter: “EVERYTHING POSTED IN THIS GROUP IS PRIVATE, TOP SECRET AND SHOULD REMAIN IN THIS GROUP. SHARING INFO OR POSTS FROM THIS GROUP WITH OTHERS WILL RESULT IN EXPULSION FROM THE GROUP AND PUBLIC SHAMING.” Amazingly, people honor the no-sharing rule. The members rely on the group’s hive mind to make decisions large and small. If you get invited into ‘Girls Night In,’ it will probably change your life. It’s like joining a sorority—a digital sisterhood where women vent, fight, offer advice, trade tips, crack jokes and critique each other’s selfies. It’s an interactive, communal diary, and a support group for womanhood. But most important of all, it’s a focus group for your life. If you’re wondering how to respond to a text from a dude, whether you should buy that jumpsuit you’re trying on at Fred Segal or if your boobs looks smoking, just post your inquiry to the group for real-time feedback. “It’s like your 1,000 best girlfriends on a group text,” founder Annaliese Nielsen told me. It’s a female hive mind and it might be the future of friendship. 👯👯👯 Nielson, 32, has always been fascinated by meeting people on the internet. “As soon as we got a computer all I did was use the internet to talk to other people,” she told me. “I was popular at school and had a ton of friends, but I was extremely interested in using the internet to talk to strangers.” Nielsen, who started the altporn site Gods Girls in her twenties, now runs Crushee, which is like a dating site but for finding new friends. The consummate party girl, Nielsen plans weekly ‘Girls Night In’ meetups at bars and night swims at the Roosevelt Hotel’s popular pool in the summer. With her voluminous blond hair, Nielsen radiates glamor, yet also comes off as extremely down-to-earth. Group members routinely describe her as “fascinating,” Annaliese Nielsen/FUSION Two years ago, Neilsen spun ‘Girls Night In’ out of another Facebook group called Girls Night Out that had begun as a few hundred girls from the L.A. party scene but ballooned into a monster group with tens of thousands of members. Nielsen wanted to create a place on the internet where women could feel safe talking about anything. “Sometimes when you ask your best girlfriends for advice they’re so biased toward you,” she told me. “If you’re being shitty to a guy they probably won’t even tell you because they’re ‘on your side.’ People who are a little more removed from each other can be more objective.” In some ways, Nielsen’s vision was not so different from how people have always used the internet. From the early internet network Usenet to LiveJournal in the aughts to Facebook and Twitter now, online social networks are where we turn for support, commiseration and advice. What’s different about ‘Girls Night In’ is the outsize role that the group plays in its members’ lives: many of its users submit their every decision, large and small, to the group, for its members’ feedback in real time. Many members post up to 10 times a day, and comment on other posts dozens of times more. (Women who don’t comment regularly are booted from the group.) Rather than turning to one or two really good friends for advice, the women of ‘Girls Night In’ consult a carefully curated crowd, constantly. “It’s my life,” one 32-year-old member told me, echoing the comments of many others. “I rarely go on ‘normcore’ Facebook, as we call it. The group is my community, it is my support system. I almost always have the page open and am engaged in it most of the day between real life.” Facebook isn’t actually uncool. You just can’t see how the cool kids are using it. Six years ago, Facebook debuted groups, along with the option to make them either “closed” or “secret.” To join a closed group, you need permission from the group’s creator. Same for secret groups, but secret groups also don’t show up in search. According to Facebook, most of those groups are small groups of friends and family composed of less than 100 people. But bigger secret groups like ‘Lolo’s Logic,’ ‘Binders Full of Women Writers’ and ‘Girls Night In’ are digital clubhouses where the network’s most interesting conversation and genuine social interaction now take place, instead of in public. Facebook isn’t actually uncool. You just can’t see how the cool kids are using it. Private Facebook groups like ‘Girls Night In’ are a fenced-off corner of the social media world where people speak honestly using their real names without fear of repercussion. You can post a boob shot knowing commenters will tell you how great they look but not repost it anywhere else on the web. You can air your angst about being married but still being upset about your ex-boyfriend of six years ago getting engaged. You can post a question knowing it will get a flurry of responses, and that they will be honest ones from people whose judgement you trust. 💅🏾 💅🏾 💅🏾 When I joined ‘Girls Night In,’ I felt a little like Lindsay Lohan’s Cady Heron in “Mean Girls” eating at the Plastics’ lunch table for the first time; it was like entering a completely different social world. I came to think of it as “Girl Internet”—and “Girl Internet” has a lot of rules. The number one rule of “Girl Internet” is that no one can share what someone else posted outside of the group. The members agreed to let me join to write this story on the condition that I agreed to honor the group’s rules of secrecy unless I had permission to do otherwise. Nielsen told me that when the group first started, lots of women were removed for things like telling a guy about something that a member posted about them or tattling on someone to their boss. “Now that the group is a fairly integral part of a member’s life,” she said. “I think they value it more than they value whatever they could gain by gossiping about it.” I whiled away hours on the group Facebook page and spoke with more than two dozen members. Most of them told me that they spend up to six hours daily interacting with the group, and that its members now make up the vast majority of their offline social network, too. Multiple women told me the group’s dominance in their lives had created rifts with their best friends and romantic partners. “My boyfriend is upset because I’m always on my phone,” one of them told me. “It’s the same issue a lot of couples face in this new age of technology. But instead of just being glued to my phone, it’s all messaging with GNI friends. Whenever there’s a question of ‘what are you doing’ or ‘who are you talking to’ the answer is always GNI. Always.” Liz Moss/FUSION It’s easy to see how it can be addicting. When I posted to the group to introduce myself, the post racked up hundreds of likes and more than 200 comments within an hour. There is always someone to give you instant advice or an ego-boosting “like” on that rant about your shitty day. If you post a selfie of your new haircut, hundreds of people will probably like it. It’s friendship on demand—if one person isn’t around to give you a virtual hug, inevitably someone else will be. The other day, a woman posted to the group that a police officer had pulled her over. He didn’t ticket her, but did later Google her, found her number and texted her. “I called the LAPD and reported because i felt so violated,” she wrote. “idk… did i do the right thing? i just wouldn’t want this to happen to anyone else.” It’s friendship on demand—if one person isn’t around to give you a virtual hug, inevitably someone else will be. She told me that she felt guilty reporting him, because he hadn’t given her a ticket, and wanted reassurance from the group that she’d done the right thing. She got that reassurance in the form of angry emoji, sad emoji and 53 comments equally outraged by her encounter. Often the inquiries are moral (whether to keep a gifted cobra skin bag), practical (how to get mac-n-cheese off a suede couch) or just plain funny (“should I get a fake baby so I can drive in the carpool lane?”). Querying the group is better than just Googling or checking Yelp. Selena Rox/FUSION ‘Girls Night In’ will happily be your therapist, too. A filmmaker who goes by Rae Threat told me that the group helped her accept her body and deal with an anxiety-causing case of psoriasis. “I’m a completely different person from before I joined the group to who I am right now,” she told me. “I go out and don’t double-check my face for redness anymore. I don’t think that I’m too fat to feel beautiful. I happily greet people instead of shying away.” Women in the group told me that it had helped them get jobs, informed them about politics and taught them how to be feminists. People talk about how to deal with being raped, cheated on or how to deal with their daughter being assaulted. During a recent medical emergency, one member posted that she needed help and hundreds of commenters rushed to assist her, online and off. “I can post about the terrible and amazing things that happen in my life and I have a support system,” she said. “I cannot imagine my life without this group.” Members are well aware that to outsiders all the selfies and gossipy chatter might make them come off as silly or vain. “Yes, we have nude threads, which may seem narcissistic to some people, but considering how much women are judged and made to feel bad about our bodies, these silly threads can be a big confidence boost,” Chara, another member told me. She told me that she has used the group as a place to vent about an ex, as well as a place to find emotional support after she was raped. “I can post about the terrible and amazing things that happen in my life and I have a support system. I cannot imagine my life without this group.” Often, I was amazed by the kindness women in ‘Girls Night In’ extended to each other. Terra Shapiro, a hairstylist and salon owner, told me that when she needed a cosigner on a loan to buy a car, 10 girls she had never met offered and one wound up actually cosigning the loan. After another woman’s house burned down, Nielson said the group raised more than $20,000 to help her. Recently, the group pooled money to pay the vet bills for a member’s sick bunny. After Nielsen posted that her grandfather was ill in Malaysia, she woke up the next morning and a flight had already been booked for her by the group. As members have moved out of L.A., it has spawned spin-off groups in San Francisco, London, New York, Chicago and Miami as well as more than 20 groups devoted to subtopics such as cooking, intersectional feminism and Bernie Sanders. Frequently members discuss what it’s like to be so “close” to 1,500 other people. It is isolating in a way—the group has its own language and political point of view and a specific kind of moral code. To be part of the group’s hive mind, you need to fit in, and that means adopting group-wide social norms. At least publicly, the women all seem to support Bernie and abortion and Kim Kardashian’s right to post as many nude selfies as she likes. Members who stray from these norms sometimes find themselves alienated or even chastised. Sometimes it eventually causes them to leave. “There aren’t really Republicans,” a member named Natasha told me. Eugenie Grey/FUSION ❤️❤️❤️ As I scrolled through post-Botox selfies, bad date tell-alls, and heart-wrenching confessions of traumatizing childhoods, it seemed at first that ‘Girls Night In’ was a group of women who were simply addicted to oversharing. In ‘Girls Night In,’ there is no thought or feeling too mundane to post. But over time, I realized that ‘Girls Night In’ is just the natural end result of constant connectivity. This is what happens when you are surrounded by people who are always up to hear about your day and offer support. The desire for that constant, supportive communication is why services like fake girlfriends exist and why millions of people in China regularly talk to Microsoft’s digital assistant Xiaoice. ‘Girls Night In’ offers the same appeal, except from real life humans who you don’t have to pay. While working on this story, I would sometimes have a funny thought, a joke I might want to text to my group of girlfriends but, because it was either the middle of the workday or the middle of the night, I’d reconsider. Then I would wonder what it would be like to post my inner monologue to ‘Girls Night In’ and instantly achieve the praise I was seeking. Sometimes, in real life, it can be hard to connect—friendships exist across a log of missed calls, awkwardly unliked Facebook posts and unanswered texts. We’ve all probably felt the disappointment of texting your bestie with something urgent and then not hearing back for hours. But in ‘Girls Night In’ the expectation of connection is always fulfilled. Perhaps, in our increasingly connected culture, all of us really need 1,500 best friends, too.

– "A constant stream of brutally frank chatter about relationships, work, sex, race, gender, and, yes, cats." That's how Kristen V. Brown, writing for Fusion, describes Girls Night In. The exclusive (and secret) Facebook group comprising some 1,500 LA-area women in their 20s and 30s also is home to "a bizarrely large quantity of nude selfies." But the name of the group isn't really Girls Night In—it changes constantly, Brown writes. Prospective members need recommendations from three women in the group. And once you're in, breaking the rules—say, by sharing something from the group with a nonmember—"will result in expulsion … and public shaming." But Girls Night In is more than just gossip, Brown writes, it's a place to get objective advice, moral support, and real-life help, such as when members raised $20,000 for another member whose house burned down. "It’s an interactive, communal diary, and a support group for womanhood." That can come at a price, though, Brown writes. Members spend up to six hours a day on the group, which can create "rifts with their best friends and romantic partners." When it comes to secret Facebook groups (they don't show up in search results), Girls Night In isn't alone, writes Alyson Krueger at Forbes. Take, for instance, Lolo's Logic, a group of women who talk sex. Members may be ostensibly "June Cleavers," the founder says. "But in there they are little freaks." Another group caters exclusively to "right-leaning conservatives," who, the founder tells Forbes, “want to post whatever we want without fear of being called racist, bigot or stupid.” Some groups offer support for specific issues, such as drug abuse. No matter a group's theme, the common denominator is that they all have strict internal rules. And LoLo's Logic requires new members to post a topless photo. (A Facebook post earned this man a traffic ticket.)

at the lhc a new energy frontier is reached , which allows for new searches of unknown particles and further tests of the standard model . from the theory side this also requires very precise predictions of cross sections and distributions , exceeding the precision of a leading - order approximation . we present a calculation of production including qcd corrections and the leptonic decays of the @xmath1- and the @xmath2-boson with off - shell effects , @xmath6 this process with leptons , photons and missing energy in the final state provides a background to new physics searches ( see , for example , ref . @xcite ) . also , this process offers the possibility to study the quartic vector - boson couplings @xmath7 and @xmath8 ( see right diagram in fig . [ fig:1 ] ) @xcite and test the standard model . it is one of the missing pieces for a full knowledge of triple vector boson production at next - to leading order ( nlo ) qcd . there has been a strong effort for the calculation of these processes . the processes with only massive vector bosons in the final state have been completely calculated @xcite . rather recently , also the nlo qcd calculation of the processes @xmath9 and @xmath10 have been completed @xcite and first results of the nlo qcd computation of the process @xmath11 have been presented @xcite . vector - boson pair production accompanied with one jet has also been studied including qcd corrections for @xmath12 , @xmath13 , @xmath14 and @xmath15 @xcite . we calculate all contributions to the processes ( [ processes ] ) up to order @xmath16 in the limit where all fermions are massless . at leading order , 71 distinct diagrams appear , which we group as three different topologies , according to the number of vector bosons attached to the quark line . an example of each class is depicted in fig.[fig:1 ] . + x at tree - level . in the right - hand diagram , the quartic coupling is marked with a dot.,title="fig:"]+ x at tree - level . in the right - hand diagram , the quartic coupling is marked with a dot.,title="fig:"]+ x at tree - level . in the right - hand diagram , the quartic coupling is marked with a dot.,title="fig : " ] for the last two topologies we also include the cases where vector bosons are radiated off the lepton lines . to speed up the calculation , invariant subparts , which appear multiple times in different feynman graphs , are computed only once per phase - space point and independently of the rest of the cross - section . hereby , we use the procedure of _ leptonic tensors _ , as first described in ref . this greatly reduces the computation time needed . for the computation of the matrix elements , we use the helicity method introduced in ref . @xcite . furthermore , by charge conservation , a @xmath1 boson must always couple to the quark line . hence , we only need to compute the left - handed chirality part . at nlo qcd , virtual and real emission diagrams contribute to the cross section . both contain infrared divergences , which must cancel in the sum according to the kinoshita - lee - nauenberg ( kln ) theorem @xcite . to handle this cancellation in a numerically stable way , we use the catani - seymour dipole subtraction method @xcite . initial - state collinear singularities are partly factorized into the parton - distribution functions . this leads to additional so - called `` finite collinear terms '' . the nlo real corrections are given by diagrams where an additional gluon is attached to the quark line which is possible in two different ways . either this gluon is a final - state particle and considered as radiated off the quark line , or an initial - state gluon which splits into a @xmath17 pair and we have an emission of a quark . with 194 different feynman diagrams , the use of leptonic tensors proves to be an advantage in this case . the presence of isolated on - shell photons requires extra care in the case of real emissions . an additional singularity arises from photon emission collinear to a massless quark . requiring a simple separation cut between photon and jet is not allowed , since the cancellation of the gluonic infrared divergences between virtual and real emission processes would be spoiled . the phase space for soft - gluon emission would be reduced while leaving untouched the virtual counterpart , leading to the non - cancellation . in principle , this problem can be solved by adding processes with quark fragmentation to photons . here , we use a simpler approach by requiring a specially crafted cut first suggested in ref . we will discuss the details of this cut in section [ sec : res ] . virtual nlo qcd corrections arise from the insertion of gluon lines into the topologies of fig . [ fig:1 ] in every possible way . therefore , the left topology gives rise to loops with up to five external particles , _ i.e. _ pentagon diagrams . for the middle and right ones at most box and triangle diagrams , respectively , appear . up to the box level , we compute the loop integrals using passarino - veltman reduction @xcite ; additionally we avoid the explicit calculation of the inverse of the gram matrix . instead , we solve a system of linear equations , which is numerically more stable close to the singular points . for the pentagon contributions , we apply the method of ref . this circumvents the appearance of small gram determinants in planar configurations of the external momenta altogether . the complete virtual corrections @xmath18 \ m_b , \label{eq : mv}\end{aligned}\ ] ] can be separated into a part which is proportional to the born matrix element , @xmath19 , and a remainder , @xmath20 . here , @xmath21 denotes the partonic center - of - mass energy , which corresponds to the invariant mass of the @xmath22 final state . for diagrams with only a single @xmath1 attached to the quark line , @xmath20 vanishes , _ i.e. _ the virtual corrections completely factorize to the born amplitude . for this factorization formula to hold , the transversality property of the photon @xmath23 must be used @xcite . then we can reuse the general results for the finite remainder already obtained in refs . @xcite , adapting the attached vector bosons to our case . another optimization can be performed by shifting parts from the pentagon diagrams into box contributions @xcite . to do this , we split the polarization vector of the vector bosons into a part proportional to the four - momentum of the boson @xmath24 and a remainder @xmath25 , which is chosen such that @xmath26 this part leads to a reduction in the size of the pentagon contributions , which we can therefore compute with lower statistics . contracting the pentagons with @xmath27 , they can be expressed as a difference of two box diagrams which are numerically faster to compute . hence , we can gain speed while keeping the total error the same . this shift also serves as a consistency check between the box and pentagon routines , as the total result must stay unchanged . to verify the correctness of our calculation , we have performed several checks . first , we have compared all tree - level amplitudes against matrix elements generated by madgraph@xcite and find an agreement of at least 14 digits , which is at the level of the machine precision . additionally , we have also compared the integrated cross section for both @xmath28 and @xmath29 against ` madevent ` and ` sherpa ` @xcite . we find an agreement at the per mill level , which is compatible with the integration error . furthermore , we have checked the implementation of the catani - seymour subtraction scheme . we have verified that for the real emission part the ratio between the differential real - emission cross section and the dipole approaches @xmath30 once we go to the soft or collinear limit . also , we have checked that finite contributions left after the cancellation of the infrared divergence can be shifted between the virtual and real parts without affecting the total result . for the phase space implementation , the @xmath31 phase space was split into three different parts . they correspond to three topologies which we have identified to give the largest contributions , which are of comparable size each . the first one corresponds to a @xmath32 s - channel structure , where possibly a massless particle ( the final - state jet for the real - emission contribution ) is radiated off first . the two outgoing particles are the massless photon and a pseudo - particle with a mass of 450 gev and a width of 100 gev . the latter one then decays into the two massive vector bosons , which in turn decay into their respective fermion anti - fermion pair , all via @xmath33 topologies . for all invariant masses of intermediate particles we apply a breit - wigner mapping to the corresponding random number , so that the peak is flattened out , integrating over the whole available energy range . the second and third structure correspond to @xmath32 s - channel production of the two massive vector bosons , where one undergoes a two - body decay into its fermions and the other one , via a @xmath34 process , into the fermions and the photon . to avoid double - counting we compute for both fermion anti - fermion pairs the difference of the invariant mass of the photon and the fermion anti - fermion pair and the mass of the corresponding vector boson . if both differences are larger than 30 gev , the phase - space point is assigned to the first topology , otherwise to that one where the difference is smaller . we perform the numerical evaluation of our calculation with an nlo monte carlo program based on the structure of the program package @xcite . as input parameters in the electroweak sector we take the @xmath1 and @xmath2 boson masses and the fermi constant . the weak mixing angle and the electromagnetic coupling constant are computed from these using tree - level relations : @xmath35 top - quark effects are not considered and all other quarks are taken massless . effects from generation mixing are neglected , as we set the ckm matrix to the identity matrix . as the central value for factorization and renormalization scales we choose the invariant mass of the leptons and the photon @xmath36 for the parton distribution functions , we choose cteq6l1 at lo and the cteq6 m set with @xmath37 at nlo @xcite . we impose the following set of minimal cuts on the rapidity @xmath38 and the transverse momentum , @xmath39 , of the final - state photon and charged leptons @xmath40 these take into account typical requirements of the experimental detectors . furthermore , leptons , photon and jet need to be well separated in order to avoid divergences from collinear photons and to be able to identify them as separate objects in the detectors . therefore , we impose @xmath41 here , a jet refers to a final - state quark or gluon in the nlo real emission contribution with @xmath42 gev and @xmath43 . the last cut in eq . ( [ eq : cuts2 ] ) eliminates the singularity from a virtual photon @xmath44 by requiring that the invariant mass of each pair of oppositely charged leptons is larger than 15 gev . for treating the collinear singularity between the photon and a parton @xmath45 , we use the procedure of ref . the event is accepted only if @xmath46 where @xmath47 is a fixed separation parameter which we set to @xmath48 . ( [ eq : frixione ] ) allows final - state partons arbitrarily close to the photon axis as long as they are soft enough . thereby , it retains the full qcd pole , which cancels against the virtual part , but it does not introduce divergences from the electroweak sector . .total cross sections at the lhc with center - of - mass energies of 7 and 14 tev for @xmath49 @xmath50 with leptonic decays , at lo and nlo , and for two sets of cuts . relative statistical errors of the monte carlo are at the per mill level . the factor 4 accounts for all combinations of final - state first- and second - generation leptons . [ cols= " < , < , < , < , < , < , < " , ] in tables [ lhcnumbers ] and [ tevnumbers ] , we present results for the integrated cross section of production for the lhc with a center - of mass energy of both @xmath51 and @xmath52 tev and for the tevatron with its center - of - mass energy of @xmath53 tev . note , for the tevatron , the cross section for @xmath54 and @xmath55 production is the same ; the given number is the individual result of one of them . besides the standard cut on @xmath56 of 10 gev we also show results for 20 gev . for the tevatron , we have reduced the cut on @xmath57 to 10 gev throughout . the cross sections shown correspond to the production of both electrons and muons for all leptons . interference effects from identical leptons in the final state are neglected , since their contribution is small . _ left : _ _ scale dependence of the total lhc cross section at @xmath58 tev for @xmath59 at lo and nlo within the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . the factorization and renormalization scales are together or independently varied in the range from @xmath60 to @xmath61 . _ _ right : _ _ same as in the left panel but for the different nlo contributions at @xmath62 with @xmath63._,title="fig:",scaledwidth=48.0% ] _ left : _ _ scale dependence of the total lhc cross section at @xmath58 tev for @xmath59 at lo and nlo within the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . the factorization and renormalization scales are together or independently varied in the range from @xmath60 to @xmath61 . _ _ right : _ _ same as in the left panel but for the different nlo contributions at @xmath62 with @xmath63._,title="fig:",scaledwidth=48.0% ] _ left : _ _ scale dependence of the total lhc cross section at @xmath58 tev for @xmath64 at lo and nlo within the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . the factorization and renormalization scales are together or independently varied in the range from @xmath60 to @xmath61 . _ _ right : _ _ same as in the left panel but for the different nlo contributions at @xmath62 with @xmath63._,title="fig:",scaledwidth=48.0% ] _ left : _ _ scale dependence of the total lhc cross section at @xmath58 tev for @xmath64 at lo and nlo within the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . the factorization and renormalization scales are together or independently varied in the range from @xmath60 to @xmath61 . _ _ right : _ _ same as in the left panel but for the different nlo contributions at @xmath62 with @xmath63._,title="fig:",scaledwidth=48.0% ] from hereon , we will focus on the lhc with a center - of - mass energy of 14 tev . in figs . [ fig : scaleplus ] and [ fig : scaleminus ] we show the dependence of the cross section for and production , respectively , when varying the renormalization and factorization scale in the interval @xmath65 around the central scale @xmath66 given in eq . ( [ eq : wzamass ] ) . we see that the variation of the lo cross section with the scale strongly underestimates the size of the nlo contributions . at the central scale , we obtain a k - factor of @xmath67 for and @xmath68 for . the dependence on the factorization scale slightly reduces when we move from a lo calculation to nlo as expected . on the other hand , the dependence on the renormalization scale shows a large variation . this is due to the fact that @xmath69 enters the cross section only at nlo , where we observe the typical leading renormalization scale dependence . when varying the factorization and the renormalization scale jointly by a factor 2 around the central scale @xmath66 , we see a change of 7.5% at lo and 6.7% at nlo for . for , the numbers change only slightly to 7.7% and 7.3% for lo and nlo , respectively . on the right - hand side of figs . [ fig : scaleplus ] and [ fig : scaleminus ] , we show the combined factorization and renormalization scale dependence of the nlo cross section split into the individual contributions . almost the entire scale dependence is given by the real - emission part , which contains the true real - emission cross section , the dipole terms from the catani - seymour subtraction scheme and the finite collinear terms . we obtain the bulk of the nlo contribution from the born matrix element and the virtual corrections proportional to it . this includes the terms from boxes and pentagons factored out in eq . ( [ eq : mv ] ) . at the central scale , it is more than twice as large as the real part . the finite virtual remainders due to box and pentagon corrections , which are shifted using eq . ( [ eq : pentshift ] ) , only yield a small contribution . the shape of their scale dependence is similar to the one of the total cross section . _ left : _ _ transverse - momentum distribution of the photon in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the transverse - momentum distribution of the photon as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ transverse - momentum distribution of the photon in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the transverse - momentum distribution of the photon as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ transverse - momentum distribution of the lepton with largest transverse momentum in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath71 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the maximal - transverse - momentum distribution of the lepton as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ transverse - momentum distribution of the lepton with largest transverse momentum in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath71 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the maximal - transverse - momentum distribution of the lepton as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ distribution of missing transverse momentum in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the missing transverse - momentum distribution as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ distribution of missing transverse momentum in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the missing transverse - momentum distribution as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ separation of the photon and the hardest lepton in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the distribution of the photon - lepton separation as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] _ left : _ _ separation of the photon and the hardest lepton in and production with leptonic decays of the w- and the z - boson at the lhc with @xmath58 tev . lo ( dashed blue line ) and nlo ( solid red ) results are shown for @xmath70 and the cuts of eqs . ( [ eq : cuts1 ] , [ eq : cuts2 ] , [ eq : frixione ] ) . _ _ right : _ _ k - factor for the distribution of the photon - lepton separation as defined in eq . ( [ eq : kfactor ] ) without ( solid red ) and including a jet veto of 50 gev ( dashed blue)._,title="fig:",scaledwidth=48.0% ] in figs . [ fig : ptgamma ] , [ fig : ptl1 ] and [ fig : ptmiss ] , we show the distribution of the transverse momentum of the photon and the hardest lepton as well as of the missing transverse momentum originating from the neutrino , respectively . on the left - hand side of each figure , we depict the differential cross section at lo and nlo both for and , and on the right - hand side we plot the differential k - factor , defined in the following way : @xmath72 we present results which do not include any cut on the additional jet , as well as including a veto on jets with @xmath73 gev . as previously , a jet is defined as a final - state parton with @xmath74 . we see that for each of the distributions the k - factor for the differential cross sections without jet veto is not constant , but shows a strong dependence on the momentum scale . in all cases it is close to the integrated one for small values of the transverse momenta coinciding with the bulk of the cross section . for large transverse momenta we observe much bigger k - factors , typically extending up to a value of three . once we include the additional jet veto , this strong dependence is largely removed . for the transverse - momentum distribution of the hardest lepton in for example ( fig . [ fig : ptl1 ] ) , we obtain k - factors between 1.10 and 1.33 over the plotted momentum range . the large differential k - factors are therefore caused by the emission of the additional jet , where the leptonic system recoils against the jet . the integrated k - factors are also reduced , namely to @xmath75 for and @xmath76 for production . in fig . [ fig : ral1 ] , we show the separation in the rapidity azimuthal - angle plane ( @xmath77 separation ) between the photon and the lepton with the largest transverse momentum . again , we observe a significant dependence of the k - factor on the value of the @xmath77 separation , varying between @xmath78 and @xmath79 . once we include the jet veto , this dependence is again much smaller . therefore , a simple approximation of rescaling the leading - order cross section with the integrated k - factor does not hold . it is necessary to perform a full nlo calculation to reproduce the correct shape of the distributions . we have calculated the nlo qcd corrections to the processes @xmath80 including full leptonic decays of the @xmath1 and @xmath2 boson . with three leptons , a photon and missing transverse energy as signature , it is an important background for searches for new physics , in particular supersymmetry . additionally , it can serve as a signal process for measuring the quartic gauge couplings @xmath81 and @xmath82 at the lhc . we find that the corrections yield a sizable increase of the cross section with respect to the leading - order result , with integrated k - factors typically around @xmath83 . the lo scale variation strongly underestimates these contributions with a variation below the @xmath84 level . varying factorization and renormalization scale @xmath85 by a factor 2 around the central value @xmath63 , we obtain a remaining scale dependence at nlo of about @xmath86 . the nlo corrections also show a significant dependence on the observable and on different phase - space regions . therefore , it is important to have a dedicated fully - exclusive nlo parton - level monte carlo code available for production . this process will be included into a future version of the program package . we would like to thank vera hankele for helpful discussions . this research was supported in part by the deutsche forschungsgemeinschaft via the sonderforschungsbereich / transregio sfb / tr-9 `` computational particle physics '' and the initiative and networking fund of the helmholtz association , contract ha-101 ( `` physics at the terascale '' ) . f.c . acknowledges partial support by european feder and spanish micinn under grant fpa2008 - 02878 . the feynman diagrams in this paper were drawn using jaxodraw @xcite . 99 j. m. campbell , j. w. huston and w. j. stirling , rept . phys . * 70 * , 89 ( 2007 ) [ arxiv : hep - ph/0611148 ] . s. godfrey , arxiv : hep - ph/9505252 ; 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we present a computation of the @xmath0 qcd corrections to production at the large hadron collider . the photon is considered as real , and we include full leptonic decays for the @xmath1 and @xmath2 bosons . based on the structure of the vbfnlo program package , we obtain numerical results through a fully flexible monte carlo program , which allows to implement general cuts and distributions of the final - state particles . the nlo qcd corrections are sizable and strongly exceed the theory error obtained by a scale variation of the leading - order result . also , the shapes of relevant observables are significantly altered . * 0.5 cm nlo qcd corrections to @xmath3 production with leptonic decays * 0.5 cm g. bozzi@xmath4 , f. campanario@xmath5 , m. rauch@xmath5 , h. rzehak@xmath5 and d. zeppenfeld@xmath5 .2 cm _ @xmath4 dipartimento di fisica , universita di milano and infn , sezione di milano , + 20133 milan , italy _ + _ @xmath5 institut fr theoretische physik , karlsruhe institute of technology , + universitt karlsruhe , 76128 karlsruhe , germany _ + 1.3 cm

localized and patterned ( labirynth ) structures in bistable media are widely considered with relevance to the storage of binary information @xcite . far enough from the phase - transition point , the complexes of dws are observed in chemical reactors , magnetic and polar ( solid and liquid ) media while their basic properties are described with equations of motion with are similar for different media . in particular , far from the critical regime , the magnetization ( polarization ) dynamics is described with the landau - lifshitz - gilbert ( llg ) equation while near the criticality it is governed by the ginbzurg - landau ( gl ) equation . recently , one observes an especial interest in 1d complexes of magnetic and polar dws due to hopes for miniaturization of memory carriers which result from achievements of current nanowire technology @xcite . the problem of stability of many - domain complexes is connected to the need of switching the domain - encoded binary information on demand since such process induces unbalanced interactions of the dws . in the present work , i analyze binary interactions between the dws ( of the bloch and neel - ising type ) with dependence on the distance of their separation and their chiralities ( opposite or like ) and i study the formation of magnetization bubbles in 1d far from and near the criticality . it enables me to consider the stability of many - domain structures . with correspondence to 2d magnetic bubbles ( which are called hard ones when their boundary is composed of alternating bloch and neel lines ) , i divide the 1d bubbles into hard ones ( composed of one bloch and one neel - ising dws ) and soft ones ( composed of two bloch dws or two neel - ising dws ) @xcite . in my recent papers on the externally - driven motion of dws , i have studied the formation of 1d hard bubbles via collision of a bloch dw with a neel ( ising ) dw in the normal and critical regimes , ( solving the llg and gl equations , respectively ) @xcite . here , the energy of soft bubbles is studied as function of the bubble length within a perturbation calcus in order to complete the picture of the dw interactions . i follow a perturbation approach to the dw interaction developed in ref . @xcite with relevance to the parametrically - driven nonlinear schrodinger equation . it differs from previous ones ( e.g. @xcite ) in terms of the perturbation expansion of the dynamical parameter ( magnetization ) whose present form ensures conservation of the magnetization length . with application to ferromagnets , the 1d approximation is relevant to crystalline nanowires with strong bulk anisotropy compared to surface magnetostatic effects ( and , especially , with circular cross section ) . the present analysis provides a basis for comparison of the dw interactions in such magnets to the interactions of dws in the nanostripes of noncrystalline ferromagnets which are studied in ref . @xcite . binary interactions od the dws and the stability of 1d bubbles are considered in sections ii and iii , with relevance to the ferromagnetic wire at low temperatures and to the subcritical systems , respectively . in section iv , the stability of many - dw 1d systems is considered on the basis of previous - section results . i consider dw solutions to the llg equation @xmath0 the first term of the r.h.s . of ( [ llg ] ) relates to the exchange spin interaction while the second ( zeeman ) term depends on the external magnetic field @xmath1 , thus , @xmath2 denotes the giromagnetic factor . the constant @xmath3 determines strength of the easy axis ( plane ) anisotropy and @xmath4 , @xmath5 . i notice that the long axis of a nanowire is an easy axis for the most often investigated magnets , however , another choice of the anisotropy axes does not influence the magnetization dynamics . since llg equation is valid only when the constraint @xmath6 is satisfied , one writes equivalent to ( [ llg ] ) equations of the unconstrained dynamics . introducing @xmath7 , one represents the magnetization components using a pair of complex functions @xmath8 , @xmath9 . the relation between the primary and secondary dynamical variables @xmath10 ensures that @xmath6 . inserting ( [ transform ] ) into ( [ llg ] ) leads , following the hirota method for solving nonlinear equations @xcite , to @xmath11f^{*}\cdot g + jg^{*}d_{x}^{2}g\cdot g & & \nonumber\\ -\left(\gamma h_{x}+\beta_{1}+\frac{\beta_{2}}{2}\right)|f|^{2}g -\frac{\beta_{2}}{2}f^{*2}g^{*}&=&0 , \nonumber\\ g^{*}\left[-{\rm i}d_{t}-jd_{x}^{2}+\alpha d_{t}\right]f^{*}\cdot g -jfd_{x}^{2}f^{*}\cdot f^ { * } & & \nonumber\\ + \left(-\gamma h_{x}+\beta_{1}+\frac{\beta_{2}}{2}\right)|g|^{2}f^ { * } + \frac{\beta_{2}}{2}g^{2}f&=&0 , \label{secondary - eq}\end{aligned}\ ] ] where @xmath12 , @xmath13 denote hirota operators of differentiation which are defined by @xmath14 for @xmath15 , the stationary single - dw solutions to ( [ secondary - eq ] ) take the form @xmath16 where @xmath17 , @xmath18 , ( a bloch dw ) or @xmath19 , @xmath20 , ( a neel dw ) . let us define @xmath21 following @xmath22 , thus , @xmath23 for bloch dw while @xmath24 for neel dw . since neither exact double - bloch nor double - neel solutions to the llg equation are not known for the case of zero external field , ( the length of the soft bubbles diverges with @xmath25 , @xcite ) , i analyze the interactions of the relevant dw pairs ( the pair of bloch dws and the pair of neel dws ) within a perturbation calculus . locally , in the vicinity of the center of @xmath26th dw , ( @xmath27 ) , one can write the magnetization in the form @xmath28 where @xmath29 denotes a stationary single - dw solution to ( @xmath30 ) [ which corresponds to ( [ single_dw ] ) ] @xmath31 , \nonumber\\ m_{x}^{(j)}(x)&=&-m{\rm tanh}[\sigma_{j}k(x - x_{0j } ) ] \label{profile1}\end{aligned}\ ] ] while @xmath32 denotes a perturbation due the presence of another dw . here @xmath33 , @xmath34 and @xmath35 ( a pair of bloch dws ) or @xmath36 ( a pair of neel dws ) . when assume @xmath37 , @xmath38 relates to the head - to - head spin structure while @xmath39 to the tail - to - tail structure . in order to satisfy the constraint @xmath6 , i apply the perturbation of the form @xmath40 where @xmath41 . it leads to @xmath42 , \nonumber\\ m_{+}&\approx&\pm\frac{1}{m}\left(m_{+}^{(1)}m_{x}^{(2)}+m_{+}^{(2)}m_{x}^{(1)}\right ) . \label{lowest_order_llg}\end{aligned}\ ] ] plus and minus relate to the bubble magnetization parallel and antiparallel to @xmath43-axis , respectively . this form of the initial magnetization reflects the fact that the interaction of topological solitons ( dws ) is not simply due to their overlap while it is accompanied by some reorientation of whole the separating them domain . therefore , the magnetization ( [ lowest_order_llg ] ) contains only products of the components of @xmath44 and @xmath45 while it does not contain linear in @xmath29 terms . let @xmath46 . inserting ( [ lowest_order_llg ] ) into the hamiltonian @xmath47 \nonumber\\ & & + \frac{\beta_{2}}{2m}({\bf m}\cdot\hat{j})^{2}-\gamma{\bf h}\cdot{\bf m},\end{aligned}\ ] ] where @xmath48 denotes the zeeman part of the hamiltonian , one arrives at the dependence of the energy @xmath49 on the distance between the dw centers @xmath50 \nonumber\\ & = & \frac{m\sqrt{j(\beta_{1}+\theta\beta_{2})}}{2 } { \rm csch}^{2\mp 1}(a/2 ) \nonumber\\ & & \times{\rm sech}^{2\pm 1}(a/2)[-2a+{\rm sinh}(2a ) ] , \\ e_{z}(a)&=&-\gamma h_{x}\frac{m}{k}i_{3}^{\pm}(a ) \nonumber\\ & = & -2\frac{\gamma h_{x}m\sqrt{j}}{\sqrt{\beta_{1}+\theta\beta_{2 } } } a[{\rm coth}(a)\mp{\rm csch}(a)],\end{aligned}\ ] ] where @xmath51 for neel dws while @xmath52 for bloch dws , and @xmath53 denote integrals given in appendix . the upper signs correspond to the pair of the dws of the opposite chiralities , the case @xmath54 , while the lower signs correspond to the pair of the dws of like chiralities , the case @xmath55 . according to the plot of energy of the dw pair ( fig . 1 ) , in absence of the external field , the interaction is attractive when both the dws are of opposite chiralities while it is repulsive in the case of like chiralities . ( 175,40 ) ( 0,-5 ) in both the cases ( of opposite and like chiralities ) , it is possible to create a stationary magnetization bubble applying an external magnetic field in the direction pursuant or opposite to the bubble magnetization , respectively . however , only in the case of @xmath55 , the function @xmath56 has a minimum at @xmath57 , ( see fig . 1 ) . therefore , only the bubble created by the dws of like chiralities is stable against external perturbations . this stable bubble corresponds to the final state of the long - term evolution of a breather . for @xmath58 , one can find strict double - bloch and double - neel solutions to llg equation , thus , one can verify our prediction on existence of soft stationary bubbles . assuming the stationary double - bloch dw solution and double - neel dw solution to ( [ secondary - eq ] ) to be of the form @xmath59 , @xmath60 , @xmath61 , one finds @xmath62 for @xmath20 , @xmath51 ( an untwisted double - neel dw ) , and for @xmath18 , @xmath52 ( an untwisted double - bloch dw ) . inserting @xmath59 , @xmath63 into ( [ secondary - eq ] ) , one finds @xmath64 for @xmath20 , @xmath51 ( a twisted double - neel dw ) , and for @xmath18 , @xmath52 ( a twisted double - bloch dw ) . the untwisted double - dws are called nuclei while the twisted double - dws are called @xmath65-dws . since typically @xmath66 while @xmath67 corresponds to the coercion - field value , ( hence , i assume @xmath68 ) , the untwisted and twisted double - dws relate to different ( parallel or antiparallel to the bubble magnetization , respectively ) directions of the external magnetic field , which ensures that @xmath69 in ( [ untwisted ] ) or ( [ twisted ] ) is determined . in order that the existence of nuclei was possible , the dws of like chiralities must attract , thus , the nucleus vanishes after turning the magnetic filed off . the prediction on stability of the @xmath65-dws and instability of nuclei is in accordance with a study of linear - excitation scattering on the soft magnetization bubbles and with simulations @xcite . ( 175,30 ) ( 0,-5 ) in order to complete the picture of the bubble formation in 1d ferromagnet , i refer to my previous study of complexes of one bloch dw and of one neel dw @xcite . in the absence of external field , such a stationary complex is described by a strict solution to the llg equation , hence , there is no interaction between the walls . an interaction appears , however , upon the field application due to a dynamically induced deformation of the dws . the external field enforces motion of any dw and its anti - wall in the opposite directions and it can induce the collision of a neel dw with a bloch dws . the result of such a collision has been found to be their mutual reflection accompanied by the transformation of the bloch wall into the neel dw and vice versa . the process can be considered as the transmission of the bloch dw through the neel dw with change of the head - to - head structure into the tail - to - tail one ( and vice versa ) which is illustrated in fig . 2 , and it is similar to the collision of spontaneously propagating ( in absence of dissipation ) dws @xcite . since , under the action of the external field , the different - type dws interact repulsively , they can form a bubble which is an 1d counterpart of the hard bubble in planar magnets . the subcritical dynamics of bistable systems is governed by the gl equation @xmath70 for @xmath71 , ( [ gl ] ) describes the evolution of bloch ( of lower energy ) and ising ( of higher energy ) dws and their complexes . the field - induced creation of 1d hard bubble ( composed of one bloch dw and one ising dw ) has been investigated in @xcite . it has been found to be similar to the dynamics of the hard bubble in the low temperature regime . for @xmath72 , the stationary complex of one ising dw and one bloch dw in an 1d subcritical system is described by a strict solution to ( [ gl ] ) , thus , both the dws do not interact @xcite . the field - driven collision of the ising dw with the bloch dw induces their mutual reflection , hence , they can form a similar hard bubble as it was described in the previous section . i mention that an analysis of linear - wave scattering on the bloch - ising complex with the parametrically - driven nonlinear schrodinger equation has shown the dynamically - induced repulsion of both the walls also @xcite . below i pay my attention to soft magnetization bubbles ( of two bloch dws or of two ising dws ) . in the first perturbation approximation , in the vicinity of the center of @xmath26th dw ( j=1,2 ) , the magnetization profile can be written as @xmath73 where @xmath74 denotes a strict ( stationary ) single - dw solution to ( [ gl ] ) for @xmath72 @xmath75 \nonumber\\ & & + { \rm i}\sin{\varphi_{j}}\sqrt{\frac{\beta_{1}-3\beta_{2}}{\mu}}{\rm sech}[\sigma_{j}k(x - x_{0j } ) ] . \label{j_thdw}\end{aligned}\ ] ] here @xmath33 , and @xmath76 , @xmath77 ( bloch dws ) or @xmath78 , @xmath36 ( ising dws ) . according to my claim on the form of the ansatz ( [ lowest_order_llg ] ) , since the interaction of dws is related to a reorientation of the separating them domain , i expect the perturbed magnetization not to contain linear in @xmath74 terms . taking the following perturbation @xmath79 $ ] , ( @xmath41 ) , leads to @xmath80 this form of the initial magnetization was used in @xcite , whereas , previous treatments of the dw interactions within the gl approximation used the ansatz @xmath81 , ( @xmath41 ) , by an analogy to the perturbation calculus for nontopological ( bright ) solitons @xcite . ( 175,30 ) ( 0,-5 ) inserting ( [ lowest_order_gl ] ) into the hamiltonian @xmath82 one arrives at the dependence of the energy @xmath49 on the distance between the dw centers . defining @xmath46 , for the interacting ising dws , one finds @xmath83,\\ e_{z}(a)&=&-\gamma h2\frac{\sqrt{\beta_{1}+\beta_{2}}}{\sqrt{\mu}k}i_{5}(a ) \nonumber\\ & = & -\gamma h4\frac{\sqrt{2j}}{\sqrt{\mu}}a{\rm coth}(a)\end{aligned}\ ] ] while for the bloch dws , ( @xmath84 is derived up to the lowest order in @xmath85 ) ; @xmath86 \nonumber\\ & = & \frac{\beta_{1}\sqrt{2j\beta_{2}}}{\mu } 2{\rm csch}^{2\mp 1}(a/2 ) \nonumber\\ & & \times{\rm sech}^{2\pm 1}(a/2)[-a{\rm cosh}(a)+{\rm sinh}(a ) ] . \\ e_{z}(a)&=&-\gamma h2\frac{\sqrt{\beta_{1}+\beta_{2}}}{\sqrt{\mu}k}i_{3}^{\pm}(a ) \nonumber\\ & = & -\gamma h4\frac{\sqrt{j(\beta_{1}+\beta_{2})}}{\sqrt{2\beta_{2}\mu}}a[{\rm coth}(a)\mp{\rm csch}(a)].\end{aligned}\ ] ] the integrals @xmath87 are given in appendix . here , the upper signs correspond to a pair of the bloch walls of opposite chiralities , the case @xmath54 while the lower signs to a pair of the bloch walls of like chiralities , the case @xmath55 . plotting the energy @xmath88 of the dw pairs ( fig . 3 ) , we see the ising dws to attract each other in the absence of external field while the character of the interaction of bloch dws to be dependent on their chiralities . in the presence of an external field parallel to the bubble magnetization , the ising walls can form a stationary state corresponding to the maximum of energy , however , it is ustable to perturbations . the bloch dws of opposite chiralities attract each other when the distance of their separation is big and they repel each other at short separation distances . because of the minims of the energy @xmath88 at @xmath57 , stable bubble of bloch dws ( a breather ) can be formed even in absence of the field . the bloch dws of like chiralities always repel in absence of the field , hence , an external field antiparallel to the magnetization of the intermediate domain enables creation of a stable bubble ( a breather ) which corresponds to the minims of @xmath89 . stability of many - dw structures is an important problem in view of the challenge of designing a nanowire - based information carrier ( a dw - racetrack memory ) @xcite . periodic structures of the bloch ( neel ) dws are stationary because of the compensation of ( attractive or repulsive ) interactions between the walls . however , bit recording requires switching the magnetization of a single domain of the memory tape on demand . for instance , the magnetization reversal can be performed via flip of the chirality of two neighboring dws in the tape , which initiates their movement towards or outwards each other and , eventually , results in their annihilation due to the appearance of uncompensated attractive forces . unfortunately , the resulting nonperiodicity of the system causes destabilization of the record . i mention that similar process is responsible for annihilation of dws during strong - current driven motion of multi - domain systems @xcite . then , the unbalanced interactions appear because , for the current intensity exceeding the walker - breakdown value , magnetization in different ( head - to - head and tail - to - tail ) dws rotates in opposite directions about the magnetic axis , ( unlike upon the application of a strong magnetic field ) . an exception is a subcritical system of bloch dws whose all the neighboring dws are of opposite chiralities and the distance of their separation corresponds to the size of the breather found in section iii . the result of changing the chirality of a single dw or a dw pair is some shift of the wall positions without any flip of the domains . aperiodic trains of dws of like chiralities ( unstable to dw interactions ) as well as trains of alternating bloch and neel ( ising ) dws ( unstable to the neel - bloch or ising - bloch transition inside the dws , @xcite ) can be stabilized by an external magnetic field whose application results in creation of soft and hard magnetization bubbles , respectively . the energy of a soft bubble increases with the field value [ see minims of @xmath90 , dotted lines in fig . 1 and fig . 3 ] , hence , unlike for weak fields , in a regime of strong field , the hard bubbles can be energetically favorable @xcite . this work was supported by polish government research founds for 2010 - 2012 in the framework of grant no . n n202 198039 . @xmath91{\rm sech}(y ) { \rm sech}(-y+a)\right\}^{2 } \bigr.\nonumber\\ & & \left . + \left\{-{\rm sech}(y)\left[{\rm tanh}(y){\rm tanh}(-y+a)+{\rm sech}^{2}(-y+a)\right]\pm { \rm sech}(-y+a)\left[{\rm tanh}(y){\rm tanh}(-y+a)+{\rm sech}^{2}(y)\right]\right\}^{2}\right){\rm d}y \nonumber\\ & & \\ i_{2}^{\pm}(a)&\equiv&\int_{-\infty}^{\infty}\left ( \left[{\rm sech}(y){\rm tanh}(-y+a)\pm{\rm tanh}(y){\rm sech}(-y+a)\right]^{2}\right){\rm d}y \\ i_{3}^{\pm}(a)&\equiv & \int_{-\infty}^{\infty}\left[{\rm tanh}(y){\rm tanh}(-y+a)\mp{\rm sech}(y){\rm sech}(-y+a)+1\right]{\rm d}y \\ i_{4}(a)&\equiv & \int_{-\infty}^{\infty}\left\{\left[{\rm sech}^{2}(y){\rm tanh}(-y+a ) -{\rm sech}^{2}(-y+a){\rm tanh}(y)\right]^{2}+\left[{\rm tanh}^{2}(y){\rm tanh}^{2}(-y+a)-1\right]^{2}\right\}{\rm d}y \\ i_{5}(a)&\equiv & \int_{-\infty}^{\infty}\left[{\rm tanh}(y){\rm tanh}(-y+a ) + 1\right]{\rm d}y\end{aligned}\ ] ] 99 p. coullet , c. riera , c. tresser , chaos * 14 * , 193 ( 2004 ) . a. s. mikhailov , k. showalter , phys . rep . * 425 * , 79 ( 2006 ) . s. s. p. parkin , m. hayashi , l. thomas , science * 320 * , 190 ( 2008 ) . m. hayashi , _ et al . _ , science * 320 * , 209 ( 2008 ) . j. f. scott , science * 315 * , 954 ( 2007 ) , a. schilling , r. m. bowman , g. catalan , j. f. scott , j. m. gregg , nano lett . * 7 * , 3787 ( 2007 ) . a. rosencwaig , w. j. tabor , t. j. nelson , phys . * 29 * , 946 ( 1972 ) . f. h. de leeuw , r. van der doel , u. enz , rep . . phys . * 43 * 689 ( 1980 ) . a. janutka , phys . e * 83 * , 056607 ( 2011 ) . a. janutka , phys . e * 83 * , 056608 ( 2011 ) . i. v. barashenkov , s. r. woodford , e. v. zemlyanaya , phys . e * 75 * , 026604 ( 2007 ) . l. korzinov , m. i. rabinovich , l. s. tsimring , phys . rev . a * 46 * , 7601 ( 1992 ) , h. tutu , h. fujisaka , phys b * 50 * , 9274 ( 1994 ) , b. a. malomed , a. a. nepomnyashchy , europhys . lett . * 27 * , 649 ( 1994 ) . a. janutka , _ domain - 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interactions of domain walls ( dws ) are analyzed with relevance to formation of stationary bubbles ( complexes of two dws ) and complexes of many domains in one dimensional systems . i investigate the domain structures in ferromagnets which are described with the landau - lifshitz equation as well as the domains in critical systems described with the ginzburg - landau equation . supplementing previous author studies on the creation of hard bubbles [ formed by one bloch dw and one neel ( ising ) dw ] in the presence of an external ( magnetic ) field , the soft bubbles consisting of two bloch dws or two neel ( ising ) dws are studied in detail . the interactions of two dws of the same kind are studied in the framework of a perturbation calculus .

WASHINGTON (AP) — The Latest on the 2016 presidential campaign, with primaries in five states Tuesday and Republican front-runner Donald Trump trying to move closer to nailing down his party's nomination (all times Eastern Standard Time): 8:00 p.m. Donald Trump and Hillary Clinton have won the presidential primary in Florida, further solidifying their leads in the hotly contested race for the Republican and Democratic nominations. For Trump, the Republican front-runner, Florida's all-or-nothing contest represents a momentous win, giving him 99 additional delegates — the largest in the quintet of contests taking place Tuesday. His victory deals a devastating blow to Florida Sen. Marco Rubio, who many in the Republican establishment had backed in the hope of derailing Trump's dash to the nomination. Clinton will be awarded delegates proportionally in keeping with Democratic regulations, but the win still catapults her ahead of rival Bernie Sanders, who came into Tuesday's contests with fresh momentum after scoring big in Michigan last week. ___ 5:15 p.m. About two-thirds of Republican primary voters in all five states voting Tuesday support temporarily banning non-citizen Muslims from entering the United States, but majorities in all five say they want immigrants already in the United States illegally to be allowed a chance to stay. That's according to early results of exit polls conducted for the Associated Press and television networks for Edison Research. Only about 4 in 10 Republican voters in each state want all immigrants in the country illegally to be deported. The proportion of GOP primary voters saying they want a ban on non-citizen Muslims entering the United States is as high as three-quarters in Missouri. ___ 5:10 p.m. About 9 in 10 Republican primary voters in five states going to the polls Tuesday are unhappy with the direction of the federal government — and on average, about 4 in 10 are angry. According to early results of exit polls conducted for the Associated Press and television networks by Edison Research, majorities of Republican primary voters in all five states say they feel betrayed by politicians from the Republican Party. In each of the five states, about half of voters say they prefer a candidate who's an outsider, while about 4 in 10 want one with political experience. ___ 5:07 p.m. White voters make up the majority of Democratic voters in four of five states going to the polls Tuesday, but all five states included large enough percentages of minority voters to potentially affect the results. According to early results of exit polls conducted for the Associates Press and television networks, black voters make up at least about one-fifth of the Democratic electorate in each states voting Tuesday, and in Florida, Illinois and North Carolina nearly 3 in 10 Democratic primary voters are black. Black voters have formed an important part of Clinton's coalition in earlier states, supporting her by about a 67 percentage point margin across 15 earlier contests where entrance or exit polls were conducted. But in Michigan a week ago, they supported her by a smaller 40 percentage point margin. In Florida, Hispanics made up about 2 in 10 Democratic and Republican primary voters. That includes about 1 in 10 GOP primary voters who are of Cuban descent. ___ 5:05 p.m. Majorities of Democrats in five states going to the polls Tuesday say they would be satisfied with both candidates as the nominee. According to early results of exit polls conducted by Edison Research for the Associated Press and television networks, voters are more likely to describe Sanders than Clinton as honest, but more likely to describe Clinton's policies as realistic. At least half of voters in each state say each of the two candidates' positions on the issues are "about right," though voters are generally more likely to say Sanders' policies are too liberal than not liberal enough and to say the opposite about Clinton. Democratic voters in all five states see Clinton as the candidate with the better chance to beat Donald Trump if he is the Republican nominee in November. ___ 4:49 p.m. Even before Tuesday's primary results are in, a group of conservative leaders is calling a meeting to discuss options for blocking Donald Trump's path to the Republican nomination — including the possibility of rallying around a third-party candidate. A person familiar with the planning for Thursday's meeting says the discussion will focus first on trying to get conservatives to unite around one candidate to compete against Trump. High-dollar donors would be mobilized to pressure other candidates to go along with that plan. The discussion will also focus on the logistics of getting a third-party candidate on state ballots, an option seen by organizers as a "lifeboat" for conservatives. Participants will discuss ballot access issues, including using an existing third party as a vehicle for a candidate or securing signatures for an independent bid. The meeting was first reported by Politico. The person familiar with the planning confirmed the meeting on the condition of anonymity because they were not authorized to discuss the gathering by name. — White House Correspondent Julie Pace ___ 4:43 p.m. Florida election officials say Republican presidential front-runner Donald Trump's name was not left off ballots in a town in south Florida, despite a small number of voter complaints. Florida is a closed-primary state, which means only registered Republicans would get a ballot listing Trump and the other GOP candidates. Palm Beach County Supervisor of Elections Susan Bucher said that independent voters can't vote in the primary. Bucher said Tuesday that some residents in Jupiter, Florida who were voting as independents in municipal elections complained when they didn't see Trump's name on the ballot. Bucher said none of the other presidential candidates were listed on those ballots either. Florida's Secretary of State Ken Detzner sent out a statement reassuring voters that Trump had not been left off any presidential ballots. ___ 4:40 p.m. Republican presidential candidate Marco Rubio says, win or lose in Tuesday's crucial Florida primary, he's staying in the race. He says there is no one in the race is "on pace to get 1,237 delegates," the number needed to secure the Republican nomination. Rubio says the latest polls showing him a distant second behind GOP front-runner Donald Trump are wrong. Rubio early voted on March 2 and is holding his primary night party in Miami. Florida elections officials are expecting a record turnout of more than 4 million voters. More than 2 million have already made their choice by early voting or absentee. The state is a closed primary. ___ 2:14 p.m. Senate Majority Leader Mitch McConnell says he spoke to Republican front-runner Donald Trump and asked him to condemn violence no matter who is responsible. McConnell told reporters that he had a conversation with the candidate Tuesday morning, the first time the two men spoke since December. The Kentucky Republican and the New York businessman discussed the recent violence that has marred Trump's rallies and protesters have clashed with the candidate's supporters. Trump earlier Tuesday backed away from a suggestion that he might cover legal costs for a supporter who was caught on video punching a black protester in the face. The supporter was later charged with assault. Trump at the time said he'd asked his "people" to "look into" paying the fees. I On ABC's "Good Morning America" Tuesday, he said, "I never said I was going to pay for fees." Asked if it had appeared he was encouraging violence with his initial statement, Trump replied, "Well, maybe so. Maybe that's why I wouldn't do it." ___ 1:22 p.m. President Barack Obama says he is deeply disturbed by the "vulgar and divisive rhetoric" directed at women and minorities, as well as the violence in the 2016 presidential campaign. That's a swipe at Republican front runner Donald Trump, who has been combative at his sometimes violent rallies and made comments about women. Obama spoke Tuesday at a unity luncheon at the Capitol to express his concern about the protests that have escalated to attacks at the Trump rallies, as well as the candidate's plan to bar Muslims and deport immigrants living here illegally. He says, "We have heard vulgar and divisive rhetoric aimed at women and minorities, and Americans that don't look like us or pray like us or vote like we do." The president adds that too many leaders have been silent about the rhetoric, tone and actual violence at Trump rallies. ___ 1:00 p.m. Hillary Clinton says on primary day in five key states that "the numbers are adding up in my favor" but she is going to keep working as hard as she can. Clinton is pointing to the general election, telling reporters in Raleigh, North Carolina, that she thinks it's important that she focuses on "the really dangerous path that Donald Trump has laid out." She says the "kind of bluster and bigotry and bullying" is disturbing to most Americans. Clinton faces Democratic rival Bernie Sanders in primary contests in five states on Tuesday: North Carolina, Florida, Ohio, Missouri and Illinois. She says she will "keep working all day on Election Day and remind people how important it is to vote" and not let "anyone get complacent." ___ 12:37 p.m. Democratic presidential candidate Bernie Sanders is closing his argument for Illinois votes by highlighting links between his Democratic opponent, Hillary Clinton, and Chicago Mayor Rahm Emanuel's troubled administration. The Democratic presidential hopeful sat down for breakfast with Cook County Board commissioner Jesus "Chuy" Garcia, who lost a surprisingly strong bid last year to unseat Emanuel. The Sanders campaign has tried to highlight links between Emanuel and Sanders' opponent, Hillary Clinton. Emanuel served as senior adviser to former President Bill Clinton and as chief of staff to President Barack Obama. The mayor is currently under fire for a police shooting scandal. Sanders is banking on a win in Illinois Tuesday to pad his surprise victory in another Rust Belt state, Michigan, on March 8. ___ 11:02 a.m. House Speaker Paul Ryan says all candidates have an obligation to do what they can to provide an atmosphere of harmony at campaign events and not incite violence. His comments Tuesday come as attacks have marred rallies led by GOP front-runner Donald Trump. The candidate canceled an event in Chicago on Friday night over protests. Ryan told reporters that there is a concerted effort by those on the left to disrupt the rallies and he condemned that. At the same time he said candidates should ensure they are appealing to people's best ideals and trying to unite the country to fix the nation's problems. Pressed on support for the eventual nominee, Ryan said that is a decision the GOP primary voters will make. ____ 10:20 a.m. Ohio Gov. John Kasich says he'll have plenty to say about one GOP candidate in particular — Donald Trump — after Tuesday's critical primaries in five states. Speaking to reporters in Genoa, Ohio, after voting for himself for president, Kasich said he'll be "forced, going forward, to talk about some of the deep concerns" he has about Trump's campaign. He said Trump's combative comments at rallies and his comments about women are of particular concern. Speaking out would not be "designed to be negative as much as it is to point out things that have been deeply disturbing." Kasich concluded that whatever happens in Tuesday's contests, he appreciates the opportunity and the attention. He added, "I just want to be a good guy, helping my country." ___ 9:44 a.m. Donald Trump has posted a big win in the GOP caucus on the Northern Mariana Islands. The party says the billionaire businessman won almost 73 percent of the vote in Tuesday's caucus. He will get all nine delegates from the U.S. territory. Texas Sen. Ted Cruz came in second with 24 percent of the vote, while Ohio Gov. John Kasich and Florida Sen. Marco Rubio finished a distant third and fourth, respectively. Both the Republican and Democratic parties hold nominating contests in U.S. territories. The residents, however, cannot vote in the general election. The party said a total of 471 people voted. Trump leads the race for delegates with 469. Cruz has 370, Rubio has 163, and Kasich has 63. It takes 1,237 delegates to win the GOP nomination.

– It's a campaign-saving win for John Kasich and a campaign-ending loss for Marco Rubio. In the latter race, Donald Trump easily defeated the Florida senator in Rubio's home state. The contest had been seen as do-or-die for Rubio, and it turned out to be die: He suspended his campaign in an evening address to supporters. Both CNN and the AP called the state as soon as the last polls closed at 8pm Eastern, with Trump up by nearly 20 points in the winner-take-all contest. In the other big race, however, Kasich got a much-needed win in his own home state of Ohio. Kasich beat Trump by around 11%, and he received a rousing cheer from supporters when he promised, "I will not take a low road to the highest office in the land," per Reuters. Trump, meanwhile, praised Rubio: "He's tough, he's smart, and he's got a great future." In the other three states voting Tuesday night, Trump racked up victories in Illinois and North Carolina, and with 99% of precincts in, he had an 0.2% lead over Ted Cruz in Missouri. Earlier, he won the Northern Mariana Islands caucus with 73% of the vote. (Click for Democratic results.)

SECTION 1. SHORT TITLE; TABLE OF CONTENTS. (a) Short Title.--This Act may be cited as the ``New Collar Jobs Act of 2017''. (b) Table of Contents.--The table of contents for this Act is as follows: Sec. 1. Short title; table of contents. Sec. 2. Findings. Sec. 3. Employee cybersecurity education. Sec. 4. Student loan repayment for certain cybersecurity employees. Sec. 5. CyberCorps scholarship-for-service program. Sec. 6. Increased funding for Advanced Technology Education program. Sec. 7. Cybersecurity training incentive for Government contracts. SEC. 2. FINDINGS. Congress find the following: (1) Domestic factory output has increased by 21 percent since June 2009, but manufacturing employment has only increased 5 percent during that time, and has been flat since late 2014. (2) As manufacturers leverage new technologies from robotics to distributed control systems to create modern factories and industrial plants, different employment requirements have emerged including the need for cybersecurity talent. (3) Leading cybersecurity experts have reported spike of 250 percent in industrial automation and control system cyber- incidents occurring during the period between 2011 and 2015 and as a result are seeking personnel with knowledge of their industry coupled with knowledge of security technology to prevent their organization from becoming victims of cyber- attacks. SEC. 3. EMPLOYEE CYBERSECURITY EDUCATION. (a) In General.--Subpart D of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by adding at the end the following new section: ``SEC. 45S. EMPLOYEE CYBERSECURITY EDUCATION. ``(a) In General.--For purposes of section 38, the employee cybersecurity education credit determined under this section for the taxable year is an amount equal to 50 percent of the aggregate qualified employee cybersecurity education expenses paid or incurred by the employer during such taxable year. ``(b) Limitation.--The amount allowed as a credit under subsection (a) for the taxable year with respect to an employee shall not exceed $5,000. ``(c) Qualified Employee Cybersecurity Education Expenses.--For purposes of this section, the term `qualified employee cybersecurity education expenses' means amounts paid or incurred for each employee who earns a certificate or degree at the undergraduate or graduate level or industry-recognized certification relating to those specialty areas and work roles that are listed in NCWF Work Roles in the document entitled, `NICE Cybersecurity Workforce Framework (NCWF)', published by the National Initiative for Cybersecurity Education (NICE) of the National Institute of Standards and Technology. ``(d) Certain Rules To Apply.--Rules similar to the rules of subsections (i)(1) and (k) of section 51 shall apply for purposes of this section.''. (b) Credit Made Part of General Business Credit.--Subsection (b) of section 38 of such Code is amended by striking ``plus'' at the end of paragraph (35), by striking the period at the end of paragraph (36) and inserting ``, plus'', and by adding at the end the following new paragraph: ``(37) the employee cybersecurity education credit determined under section 45S(a).''. (c) Denial of Double Benefit.--Subsection (a) of section 280C of such Code is amended by inserting ``45S(a),'' after ``45P(a),''. (d) Clerical Amendment.--The table of sections for subpart D of part IV of subchapter A of chapter 1 of such Code is amended by adding at the end the following new item: ``Sec. 45S. Employee cybersecurity education.''. (e) Effective Date.--The amendments made by this section shall apply to individuals commencing apprenticeship programs after the date of the enactment of this Act. SEC. 4. STUDENT LOAN REPAYMENT FOR CERTAIN CYBERSECURITY EMPLOYEES. Section 455 of the Higher Education Act of 1965 (20 U.S.C. 1087e) is amended by adding at the end the following: ``(r) Loan Repayment for Cybersecurity Workers in Economically Distressed Area.-- ``(1) In general.--The Secretary shall cancel the amount described in paragraph (2) of the balance of interest and principal due, in accordance with such paragraph, on any eligible Federal Direct Loan not in default for a borrower who-- ``(A) makes 36 consecutive monthly payments on the eligible Federal Direct Loan after the date of the enactment of this section pursuant to any one or a combination of the following-- ``(i) payments under an income-based repayment plan under section 493C; ``(ii) payments under a standard repayment plan under subsection (d)(1)(A), based on a 10- year repayment period; ``(iii) monthly payments under a repayment plan under subsection (d)(1) or (g) of not less than the monthly amount calculated under subsection (d)(1)(A), based on a 10-year repayment period; or ``(iv) payments under an income contingent repayment plan under subsection (d)(1)(D); and ``(B) during the period in which the borrower makes each of the 36 consecutive monthly payments described in subparagraph (A), has been employed in a cybersecurity job-- ``(i) located in an area that, for at least 12 of such consecutive monthly payments is an economically distressed area; and ``(ii) that requires that the borrower work in the economically distressed area no less than 60 percent of total work hours. ``(2) Cancellation amount.--After the conclusion of the employment period described in paragraph (1), the Secretary shall cancel the lesser of the following: ``(A) The obligation to repay the balance of principal and interest due as of the time of such cancellation, on the eligible Federal Direct Loans made to the borrower under this part. ``(B) $25,000. ``(3) Ineligibility of double benefits.--No borrower may, for the same service, receive a reduction of loan obligations under both this subsection and-- ``(A) subsection (m); or ``(B) section 428J, 428K, 428L, or 460. ``(4) Definitions.--In this section: ``(A) Cybersecurity job.--The term `cybersecurity job' means-- ``(i) a skill role as defined in the NCWF Work Roles by the National Initiative for Cybersecurity Education (NICE) Cybersecurity Workforce Framework (NCWF) of the National Institute of Standards and Technology, Special Publication 800-181, or any successor document; or ``(ii) teaching a cybersecurity course for a skill role described in clause (i). ``(B) Economically distressed area.--The term `economically distressed area' means an area that meets one or more criteria under section 301(a) of the Public Works and Economic Development Act of 1965 (42 U.S.C. 3161(a)).''. SEC. 5. CYBERCORPS SCHOLARSHIP-FOR-SERVICE PROGRAM. (a) Funding Increase.--It is the sense of the Congress that the number of scholarships awarded by the National Science Foundation for scholarships awarded under the Federal cyber scholarship-for-service program established by section 302 of the Cybersecurity Enhancement Act of 2014 for fiscal year 2018 and each succeeding fiscal year should be not less than double the number of such scholarships awarded for fiscal year 2017. (b) Cybersecurity Course Instruction.--Section 302 of the Cybersecurity Enhancement Act of 2014 (15 U.S.C. 7442) is amended-- (1) in subsection (a), by striking ``and security managers'' and inserting ``security managers, and cybersecurity course instructors,''; and (2) in subsection (d), by adding at the end the following: ``Such work may include teaching a cybersecurity course for a skill role as defined in the NCWF Work Roles by the National Initiative for Cybersecurity Education (NICE) Cybersecurity Workforce Framework (NCWF) of the National Institute of Standards and Technology, Special Publication 800-181, or any successor document.''. (c) Elimination of Priority for Federal Government Employment Placements.--Section 302(b) of such Act (15 U.S.C. 7442(b)) is amended-- (1) in paragraph (1), by adding ``and'' at the end; (2) in paragraph (2), by striking ``; and'' and inserting a period; and (3) by striking paragraph (3). SEC. 6. INCREASED FUNDING FOR ADVANCED TECHNOLOGY EDUCATION PROGRAM. It is the sense of the Congress that the amount expended for the Information Technology and Cybersecurity Division of the Advanced Technological Education program of the National Science Foundation established by section 3(a) of the Scientific and Advanced-Technology Act of 1992 (Public Law 102-476) for fiscal year 2018 should be an amount equal to not less than 110 percent of the amount expended for such division for fiscal year 2017. SEC. 7. CYBERSECURITY TRAINING INCENTIVE FOR GOVERNMENT CONTRACTS. (a) In General.--Subpart 15.3 of the Federal Acquisition Regulation shall be revised to require, in the evaluation of a competitive proposal received in response to a solicitation for a contract valued in excess of $5,000,000, that the head of an executive agency award a five percent score increase to each competitive proposal submitted by a qualified offeror. (b) Definitions.--In this section: (1) Executive agency.--The term ``executive agency'' has the meaning given that term in section 102 of title 40, United States Code. (2) Qualified offeror.--The term ``qualified offeror'' means a business that has claimed the employee cybersecurity education credit under section 45S of the Internal Revenue Code of 1986, as added by section 3, at least once within the three- year period preceding the date on which the business submits a competitive proposal for a contract valued in excess of $5,000,000.

New Collar Jobs Act of 2017 This bill amends the Internal Revenue Code to establish an employee&nbsp;cybersecurity education tax credit, not to exceed $5,000&nbsp;a year per employee,&nbsp;for an employer&nbsp;who incurs costs for an employee who earns a certificate or degree at the undergraduate or graduate level or an industry-recognized certification listed in the National Initiative for Cybersecurity Education's Cybersecurity Workforce Framework. The Federal Acquisition Regulation is amended to&nbsp;provide a business that utilizes the employee cybersecurity education tax credit and submits a bid for a competitive federal contract valued at more than $5 million a 5% increase in the business's&nbsp;bid score. The bill amends the Higher Education Act of 1965 to authorize the Department of Education to cancel eligible&nbsp;Federal Direct Loans&nbsp;for borrowers who have: (1) made 36 consecutive monthly payments, and (2) held a cybersecurity job in an economically distressed area during at least 12 months of payments. The program&nbsp;will&nbsp;cancel up to $25,000 in loans. The Cybersecurity Enhancement Act of 2014 is amended to include teaching cybersecurity as an acceptable employment&nbsp;option to satisfy&nbsp;post-award obligations&nbsp;for recipients of a CyberCorps Scholarship-for-Service award.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Ellie Helton, Lisa Colagrossi, Teresa Anne Lawrence, and Jennifer Sedney Focused Research Act'' or ``Ellie's Law''. SEC. 2. FINDINGS. The Congress makes the following findings: (1) An estimated 6 million people in the United States, or 1 in 50 people, have an unruptured brain aneurysm. (2) Each year, an estimated 30,000 people in the United States suffer a brain aneurysm rupture. Ruptured brain aneurysms are fatal in about 40 percent of cases. Of those who survive, about 66 percent suffer some permanent neurological deficit. (3) Brain aneurysms are more likely to occur in women than in men by a 3 to 2 ratio. People who experienced a brain aneurysm rupture include the following: (A) Ellie Helton. On July 16, 2014, Ellie Helton, a vibrant, loving 14-year-old from Apex, North Carolina, passed away as a result of a ruptured aneurysm, stunning her parents, two sisters, and many, many loved ones. A day earlier, on her second day of high school, she woke up with a terrible headache after a plum-sized aneurysm on her brain stem ruptured. While she suffered headaches throughout her life, she was never diagnosed. Ellie was an avid reader and excellent student, loved the arts, and was incredibly creative. She had an unwavering, constant love for the family and friends in her life. (B) Lisa Colagrossi. On March 20, 2015, Lisa Colagrossi--WABC Eyewitness News reporter, wife of 17 years, and mother of two sons--unexpectedly passed away at the age of 49 years after suffering a massive ruptured brain aneurysm. Despite experiencing one of the classic warning signs of a brain aneurysm (the ``worst headache of my life''), Lisa's passing came as a tremendous shock to her family and friends, who did not know what a brain aneurysm was, let alone its signs and symptoms. She is remembered for being a loving wife, a mother, and a successful reporter, and for her love of the New York Rangers. (C) Teresa Anne Lawrence, devoted mother of three, beloved wife, and staple of her community, collapsed while visiting her son's school on December 8, 1983. She had been struggling with and taking medication for hypertension for several years. At age 34, after being unconscious for four days, she passed away as a result of a brain aneurysm. Her loving husband and extended family were left to raise their children, whom Teresa cherished so much. (D) Jennifer Sedney. On December 25, 2013, Jennifer Sedney, a beautiful, accomplished young woman, passed away suddenly at the age of 27 from a ruptured brain aneurysm. Her only symptom was the ``worst headache of her life'', which none of her friends or family realized was a symptom of a potentially fatal condition. Jenny was a jogger, a disciplined exerciser, and a successful health care consultant and had recently launched a health blog founded on three principles--``bee curious, bee radiant, bee well''. Her brother, mother, father, and a large devoted network of friends and relatives remember her every day. (4) The combined lost wages of survivors of brain aneurysm ruptures and their caretakers are approximately $138,000,000 per year. (5) Despite the widespread prevalence of this condition and the high societal cost it imposes on the Nation, the Federal Government only spends approximately $0.83 per year on brain aneurysm research for each person afflicted with a brain aneurysm. (6) The first three iterations of the International Study on Unruptured Intracranial Aneurysms (ISUIA) have advanced researchers' and clinicians' understanding of how to most effectively manage and treat unruptured intracranial aneurysms. SEC. 3. FUNDING. (a) Authorization of Appropriations.--To conduct or support further comprehensive research on unruptured intracranial aneurysms, studying a broader patient population diversified by age, sex, and race, there are authorized to be appropriated to the National Institute of Neurological Disorders and Stroke $5,000,000 for each of fiscal years 2018 through 2022, to remain available through September 30, 2026. (b) Supplement, Not Supplant.--Any funds made available pursuant to this section shall supplement, not supplant, other funding made available for research on brain aneurysms.

Ellie Helton, Lisa Colagrossi, Teresa Anne Lawrence, and Jennifer Sedney Focused Research Act or Ellie's Law This bill authorizes appropriations for the National Institute of Neurological Disorders and Stroke to conduct or support research on unruptured brain aneurysms in a patient population diversified by age, sex, and race.

ram pressure ( and related processes ) by the intracluster medium ( icm ) can remove a galaxy s gas ( gunn & gott 1972 ) . this process has been observed in various stages ; for example , vollmer ( 2009 ) separates virgo galaxies into pre - peak , peak , and post - peak ram pressure groups . the amount of time that a galaxy has been stripped can be estimated using the length of the observable tail and the velocity of the galaxy ( e.g. oosterloo & van gorkom 2005 ; sun et al . this calculation is uncertain due to difficulties in determining the three dimensional galaxy velocity . another assumption implicit in this calculation is that the observed tail provides the true length of the stripped gas . in fact , tails have been observed in h@xmath0 , h@xmath1 , and x - ray emission , although never all from the same tail ( e.g. oosterloo & van gorkom 2005 ; koopmann et al . 2008 ; kenney et al . 2008 ; yoshida et al . 2002 ; yoshida et al . 2004a , b ; sun et al . 2007 ; sun et al . 2006 ; sun et al . 2010 ; machacek et al . 2006 ; sun & vikhlinin 2005 ) . the lengths of tails observed in different wavelengths can be quite different ; for example the h@xmath0 tail of ngc 4388 is nearly three times as long as the observed h@xmath1 tail ( oosterloo & van gorkom ; yoshida et al . another method used to calculate the age of a tail is to use the estimated survival time of h@xmath1 , as in gavazzi et al . ( 2001 ) . however , it is still not clear what dictates cloud survival or even what conditions are necessary to produce the various types of emission ( h@xmath1 , x - ray , and h@xmath0 ) . can all three types of emission coexist ? what physical processes dominate the heating and mixing of stripped gas into the icm ? these processes include : turbulent mixing , which can generate intermediate temperature and density gas at constant pressure ; shock heating , which heats the ism ; radiative cooling , which can lead to recompression of heated gas , and heat conduction , which can evaporate small clouds . in this work we focus on answering these questions by simulating gas stripping and comparing our simulated tail to a single observed stripped galaxy , eso 137 - 001 , which has been studied observationally in some detail . eso 137 - 001 is in a3627 , which is the closest massive cluster ( z=0.0163 , @xmath2 = 925 km s@xmath3 and kt = 6 kev ) , similar to coma and perseus in mass and galaxy content ( sun et al . 2009 and references therein ) . eso 137 - 001 is a small ( 0.2l@xmath4 ; sun et al . 2006 ) , blue emission - line galaxy ( woudt et al . 2004 ) , that is @xmath5200 kpc from the center of the cluster in projection . because its radial velocity is close to the average velocity of a3627 ( woudt et al . 2004 ; woudt et al . 2008 ) , most of its motion is likely in the plane of the sky , and therefore the stripping process is seen edge - on . sun et al . ( 2006 ) found a @xmath570 kpc x - ray tail pointing away from the cluster center using _ chandra _ and xmm-_newton _ data . sun et al . ( 2007 ) then discovered a 40 kpc h@xmath1 tail with over 30 emission - line regions extending through the length of the h@xmath1 tail , and concluded that the emission - line regions are giant h@xmath0 regions . in a recent follow - up paper , sun et al . ( 2009 ) used deep _ chandra _ data and _ gemini _ spectra to characterize the x - ray tail and h@xmath0 regions in detail . they found a narrower secondary x - ray tail with a similar length . they also confirmed that 33 emission - line regions are h@xmath0 regions , with the furthest seven regions beyond the tidally - truncated halo of 15 kpc that is calculated in sun et al . ( 2007 ) using simulations by gnedin ( 2003 ) . in addition to these distinct h@xmath0 regions , they find diffuse h@xmath1 emission . vollmer et al . ( 2001 ) searched for h@xmath0 in a3627 , and did not detect any h@xmath0 in or around eso 137 - 001 with a limiting column density of 2 @xmath6 10@xmath7 @xmath8 and a resolution of 15 " . in fact , of the @xmath580 galaxies identified by woudt et al . ( 1998 ) in their search region , vollmer et al . ( 2001 ) detected only 2 in h@xmath0 , finding that the h@xmath0 detection rate in a3627 is similar to that in coma . sivanandam et al . ( 2009 ) observed eso 137 - 001 with irac and irs on _ spitzer_. the irs data extended to 20 kpc from the galaxy along the x - ray tail , and warm ( @xmath5160 k ) molecular hydrogen was detected throughout the length of the observed region . the observed region contains @xmath52.5 @xmath6 10@xmath9 m@xmath10 warm h@xmath11 gas . they also identify star - forming regions using 8 @xmath12 m data , which coincide with h@xmath1 emitting regions . there has been a substantial amount of theoretical work investigating ram pressure stripping in general ( e.g. schulz & struck 2001 ; quilis , bower & moore 2000 ; roediger & brggen 2008 , kronberger et al . 2008 ; kapferer et al . 2009 ) see tonnesen & bryan ( 2009 , 2010 ; hereafter tb09 and tb10 ) for a more detailed discussion . there have also been simulations designed to predict or interpret observational characteristics of ram pressure stripped tails and the remaining disks ( e.g. vollmer et al . 2005 , 2006 , 2008 ) , but detailed , quantitative predictions of all three observational probes have been missing to date ( h@xmath0 , diffuse h@xmath1 , and x - ray emission ) . in our previous work ( tb10 ) , we ran a set of high resolution simulations ( about 38 pc resolution , which is small enough to marginally resolve giant molecular clouds ) to understand how a multiphase ism could affect the survival and structure of ram pressure stripped gas . we focused on how density fluctuations that are observed in the multiphase ism of galaxies can affect gas tails . including radiative cooling allowed us to estimate the density of and emission from h@xmath0 , h@xmath1 , and x - ray gas separately . we found that both the morphology and velocity structure of our tails agreed with observations of long gas tails ( e.g. oosterloo & van gorkom 2005 ) . our simulations also resulted in observable amounts of h@xmath0 and h@xmath1 emission . however , the x - ray tail had a low surface brightness , which we attributed to the low pressure of the surrounding icm . in this paper we will use the same method as in tb10 , but have chosen icm parameters comparable to the icm around eso 137 - 001 . by focusing on the level of agreement between our simulations and the observations of eso 137 - 001 we will be able to discuss the importance of physical mechanisms such as heat conduction , as well as predict the conditions under which h@xmath0 , h@xmath1 , and x - ray emission are produced in stripped tails . the paper is structured as follows . after a brief introduction to our methodology , we provide the characteristics of our simulations and our method of producing simulated observations ( 2 ) . we then ( 3 ) present our results , specifically focusing on the comparison with eso 137 - 001 . in 4 we discuss the broader implications of our simulation , and discuss our choice of radiative cooling floor and resolution in 5.1 - 2 . finally , we conclude in 6 with a summary of our results and predictions for observers . c | c variable & value + m@xmath4 & @xmath13 m@xmath14 + a@xmath4 & 4 kpc + b@xmath4 & 0.25 kpc + m@xmath15 & @xmath16 m@xmath14 + r@xmath15 & 0.4 kpc + r@xmath17 & 23 kpc + @xmath18 & @xmath19 g @xmath20 + we use the adaptive mesh refinement ( amr ) code _ enzo _ ( bryan 1999 ; norman & bryan 1999 ; oshea et al . 2004 ) . our simulated region is 311 kpc on a side with a root grid resolution of @xmath21 cells . we allow an additional 6 levels of refinement , for a smallest cell size of 38 pc . we refine our simulation based on the local gas mass , such that a cell was flagged for refinement whenever it contained more than about @xmath22 @xmath23 . we found that this refined most of the galactic disk to 38 pc resolution by the time the wind hit ; dense clumps in the wake were also refined to 38 pc resolution , while more diffuse components had lower resolution . the simulation includes radiative cooling using the sarazin & white ( 1987 ) cooling curve extended to low temperatures as described in tasker & bryan ( 2006 ) . to mimic effects that we do not model directly ( such as turbulence on scales below the grid scale , uv heating , magnetic field support , or cosmic rays ) , we cut off the cooling curve at a minimum temperature @xmath24 so that the cooling rate is zero below this temperature . in the simulations described here we use either @xmath25 k , or @xmath26 k. both allow gas to cool below the threshold for neutral hydrogen formation . in tb09 , we found that the minimum temperature affected the range of masses and sizes of clouds forming in the disk , and the distribution of clouds throughout the disk , although the range of gas densities was very similar . the @xmath26 k case resulted in a more fragmented disk whose small clouds took longer to strip . therefore the timescales for gas stripping differed , although the total amount of gas lost was similar . in the simulations presented in this paper , we find that the cooling floor affects the amount of fragmentation in the disks , but not the mass - distribution of gas densities . the larger radii of the remaining gas disks in the two @xmath26 k runs are due to the survival of dense clouds in the outer disk ( figures [ fig : xrayproj ] , [ fig : haproj ] , and [ fig : hiproj ] ) . in tb10 , we found that the structure of the wake also depends somewhat on @xmath27 . since the publication of tb10 , we found and corrected an error in our implementation of the cooling rate that resulted in a slight shift in the peak of the cooling curve around @xmath28 k , but did not significantly affect cooling at low and high temperatures ( this affected only the @xmath26 k simulation ) . tests showed that this had only a small impact on the dynamics of the flow , and on the predicted h@xmath0 and x - ray measures , but did strongly affect the predicted h@xmath1 emission , which is extremely sensitive to the gas temperature around @xmath28 k. this explains the enhanced h@xmath1 emission in this paper for the @xmath26 k run as compared to tb10 . c | c variable & value + m@xmath29 & @xmath16 m@xmath14 + a@xmath29 & 7 kpc + b@xmath29 & 0.4 kpc + c | c | c | c | c | c run & v@xmath30 ( km / s ) & p@xmath30 ( dyne/@xmath31 ) & t@xmath30 ( k ) & p@xmath32 ( dyne/@xmath31 ) & t@xmath33 ( myr ) + t80vh & 1900 & 4.2 @xmath6 10@xmath34 & 8.3 @xmath6 10@xmath35 & 11.6 @xmath6 10@xmath34 & 85 + t3vh & 1900 & 4.2 @xmath6 10@xmath34 & 8.3 @xmath6 10@xmath35 & 11.6 @xmath6 10@xmath34 & 75 + t3vl & 1413 & 2.66 @xmath6 10@xmath34 & 7.3 @xmath6 10@xmath35 & 5.29 @xmath6 10@xmath34 & 110 + sun et al . 2010 & & 1.8 @xmath6 10@xmath34 & @xmath57 @xmath6 10@xmath35 & & + our galaxy model is the same as in tb10 and tb09 , which used the spiral galaxy model described in roediger & brggen ( 2006 ) . we list the model parameters for our galaxy in tables [ tbl - const4 ] and [ tbl - gconst4 ] . the stellar and dark matter components of the galaxy are static potentials . as in tb09 and tb10 , our galaxy position and box size allows us to follow gas 200 kpc above ( in the wind , or z , direction ) the galaxy . to identify gas that has been stripped from the galaxy , we also follow a passive tracer which is initially set to 1.0 inside the galaxy ( defined as gas that is above the icm density ) and @xmath36 outside . in the following analysis , we will use a minimum tracer fraction of 0.25 to find gas stripped from the galaxy ( as in tb10 ) . the galaxy initially evolves in a static , high - pressure icm with @xmath37 8.7 @xmath6 10@xmath38 g @xmath20 and @xmath39 9.069 @xmath6 10@xmath40 k ( @xmath377.57 @xmath6 10@xmath38 g @xmath20 and @xmath39 1.04294 @xmath6 10@xmath9 k for the slower wind case ) , to allow cool , dense gas to form in the galaxy ( each of our three runs has about 3 @xmath6 10@xmath41 m@xmath10 of gas with densities at or above 10@xmath42 g @xmath20 when the wind hits the disk ) . this naturally generates a multiphase ism ( see tasker & bryan 2006 and tb09 for more discussion of the ism properties ) . after 155 myrs , we reset the boundary conditions to generate a constant icm inflow along the inner z - axis , which is always face - on to the galaxy . in table [ tbl - runs ] we show the details of each of the three runs . the table includes the icm parameters and the time after the wind has hit the galaxy at which the x - ray tail is 80 kpc long ( this is how we choose the outputs to compare to the observations of eso 137 - 001 ) . ` t80 ' indicates cooling to 8,000 k and ` t3 ' indicates cooling to 300 k , while ` vh ' and ` vl ' indicate high and low velocity wind , respectively . see tb09 for other details regarding the general numerical setup , and tb10 for a discussion of the general impact of the cooling floor on the tail structure . in order to compare with both observations and our previous work , we use a face - on wind direction . _ enzo _ outputs the density and temperature of the gas in each cell . to transform these values into h@xmath0 column density and h@xmath1 intensity , we used cloudy , version 08.00 of the code last described by ferland et al . ( 1998 ) . using a table of temperatures and densities , we calculated the hydrogen neutral fraction and h@xmath1 emissivity . this table is then used to calculate the observational quantities for each cell , which are then summed to generate an image . this is described in detail in tb10 , but briefly , we included cmb radiation , the cosmic ray background , bremsstrahlung radiation from the icm and the 2005 version of the haardt & madau ( 2001 ) @xmath43 metagalactic continuum , as implemented by cloudy . we chose to calculate the neutral fraction and h@xmath1 emissivity for a plane - parallel gas cloud of width 100 pc . we selected this width because it loosely corresponds to the cell size of most of the gas in the tails , and accounts approximately for attenuation of the ionizing background radiation . if we assumed the radiative thin limit ( by using a very small cloud size in cloudy ) , it would somewhat decrease the amount of h@xmath0 we predict , and increase the h@xmath1 emission for dense , low - temperature gas . we discuss the use of different cloud sizes in detail in tb10 , however , in the simulations in this paper we find that using a 10 pc cloud does not significantly change our h@xmath1 flux nor our h@xmath0 column densities because of the higher densities in our tail gas . this indicates that radiative transfer effects are not that important for this work . to create x - ray surface brightness projections , we use a spectral lookup table that depends on temperature and density , assuming a constant metallicity of 0.3 solar , as computed using a raymond - smith code ( raymond & smith 1977 ) , as updated in xspec ( arnaud 1996 ) . the x - ray band we use is 0.5 kev to 2.0 kev , following sun et al . in this section , we compare our simulated stripped tail to observations of eso 137 - 001 . we choose an output time at which the x - ray tail length is about 80 kpc in order to match the observations of sun et al . ( 2010 ) ; this time is shown in table [ tbl - runs ] . we are using this comparison with the observations of eso 137 - 001 to better understand the physics at work in producing x - ray , h@xmath1 , and h@xmath0 tails , so we have not tuned our simulation specifically to find an exact match to the galaxy and tail of eso 137 - 001 . while our icm parameters are similar to those of the icm near eso 137 - 001 , they are not the same . the final row in table [ tbl - runs ] displays the icm parameters from the observations of sun et al . we have not attempted to model the exact angle between the galaxy s disk and orbital motion ( woudt et al . ( 2008 ) find a position angle of 125@xmath44 ) , and instead use a face - on wind , and we are using a larger galaxy ( initially our galaxy has a radius of 26 kpc , and in the comparison projections the radius is about 15 kpc , while the 2mass isophotal radius for eso 137 - 001 is 6.1 kpc ( skrutskie et al . 2006 ) ) . in the following comparisons we will take note of the differences between our simulations and the observations of sun et al . ( 2006 ; 2007 ; 2010 ) . we have chosen the output time at which each simulation has an x - ray tail whose length is about 80 kpc . this means that the length of time that each galaxy has been stripped in the different simulations is not the same . in table [ tbl - tempmass ] , we list the amount of gas in the tail in three different temperature ranges . these masses include all of the gas above 10 kpc from the disk with tracer fractions of at least 25% , so some of the gas included is at low density , as shown in figure [ fig : rhot ] ( too low to be observable ) . nevertheless , it can be very loosely stated that longer stripping times may result in more mixing of hot gas into the icm , and in more dense gas being stripped and condensing into clouds in the tail . this can be seen by comparing t80vh or t3vl with t3vh ( of course there are also other differences in the simulations that influence the tail gas , such as cooling floor and icm pressure ) . however , we stress that in this paper we mainly focus on what causes a tail to be bright in x - ray and h@xmath1 emission , so focus more on icm pressure than the amount of time a galaxy has been stripped ( although we do consider this timescale in our discussion of heat conduction ) . c | c | c | c run & t @xmath45 10@xmath46 k & 10@xmath46 @xmath45 t @xmath45 10@xmath47 k & 7 @xmath6 10@xmath47 @xmath45 t @xmath45 4 @xmath4810@xmath9 k + & 10@xmath41 m@xmath10 & 10@xmath41 m@xmath10 & 10@xmath41 m@xmath10 + t80vh & 1.4 & 1.6 & 6.0 + t3vh & 1.1 & 1.2 & 9.1 + t3vl & 4.2 & 2.9 & 5.9 + we first compare the x - ray characteristics of our simulations to observations . the x - ray surface brightness projections of our runs are shown in figure [ fig : xrayproj ] . as in sun et al . ( 2006 ; 2010 ) , we measure the x - ray emission between 0.5 - 2.0 kev . the surface brightness profiles along the tails are in rough agreement with that of eso 137 - 001 , which is bright near the disk and has a second bright region about 40 kpc from the disk before becoming less luminous to the end of the tail . our model does not reproduce the exact x - ray surface brightness profiles : we do not have a model that includes both the bright emission near the disk and a surface brightness decrease across the entire tail before the second brightness peak . c | c | c | c | c run or & _ l @xmath6 w _ & l@xmath49 & l@xmath50 corrected@xmath51 & t + observation & ( kpc @xmath6 kpc ) & ( 10@xmath52 erg s@xmath3 ) & ( 10@xmath52 erg s@xmath3 ) & ( 10@xmath9 k ) + t80vh & 80 @xmath6 26 & 66.3 & 4.8 & 2.5 + t3vh & 80 @xmath6 30 & 93.0 & 5.1 & 2.1 + t3vl & 80 @xmath6 30 & 41.9 & 3.6 & 1.4 + sun et al . 2010 & 80 @xmath6 8 , 80 @xmath6 7 & ( 8.3 @xmath53 0.4 ) & ( 8.3 @xmath53 0.4 ) & 0.93 @xmath53 0.05 + to make the x - ray projections , we adopted a minimum observable surface brightness of 7.1 @xmath6 10@xmath54 erg @xmath8 s@xmath3 , which we estimated from the total luminosity of the observed tail and brightness profiles in sun et al . ( 2010 ) ( our cluster background is about 3.6 @xmath6 10@xmath54 erg @xmath8 s@xmath3 ) . this results in a luminosity difference of an order of magnitude between the lowest and highest surface brightness features in all of our simulated tails , similar to that in the observed tail of eso 137 - 001 . our tails are narrow and show a nearly constant width along the entire tail , in agreement with the x - ray morphology reported in sun et al . ( 2006 ; 2010 ) . this is in contrast to simulations that do not include radiative cooling and produce flared tails ( e.g. roediger , brggen & hoeft 2006 ) however , it is clear that we do not have separated x - ray tails as in the observations . this is not surprising given the explanation of sun et al . ( 2010 ) that the two tails likely result from the stripping of two spiral arms . as we discuss in detail in tb09 , our disks fragment but do not form spiral arms . in table [ tbl - xtail ] , we list some of the characteristics of our simulated x - ray tails to compare with the observed tail . to calculate the luminosity of the tail , we find the total energy emitted and subtract the background emission from the icm . as the table demonstrates , the simulated tails are wider , more luminous , and have a higher average ( emission - weighted ) temperature than the ( spectroscopic ) temperature measured by sun et al . we now address these differences . the tail is most likely wider because we are modeling a large spiral galaxy , while eso 137 - 001 is thought to be a @xmath5 0.2l@xmath4 galaxy , with a smaller galactic radius ( sun et al . 2006 and references therein ) . in fact , the entire volume of the tail in any of our three runs is nearly an order of magnitude larger than the tail of eso 137 - 001 ( we assume that the tails are cylindrical with the heights and diameters denoted in table [ tbl - xtail ] ) . the other difference is that our icm pressure is also somewhat larger than calculated in sun et al . ( 2010 ) by either a factor of 1.47 ( t3vl ) or 2.33 ( t3vh and t80vh ) . these differences in tail volume and icm pressure impact the observables in two ways . first , as we discuss in tb10 and below , the compression of stripped gas by the icm determines the temperature and density distribution of gas in the tail . therefore , a higher icm pressure results in higher - density hot gas ( @xmath55 k ) , which will have a higher x - ray emissivity . as we argue in the next section , this makes the x - ray luminosity proportional to the icm pressure . second , if we assume that the filling factor of x - ray emitting gas is the same in our simulations as in the tail of eso 137 - 001 , then the total luminosity is also directly proportional to the volume of the entire tail . the x - ray luminosity after applying these corrections is also shown in table [ tbl - xtail ] ( assuming x - ray luminosity is directly proportional to both the icm pressure and the volume of the tail ) . when we account for these differences , our measured luminosities are within about a factor of two of the x - ray luminosity of eso 137 - 001 . as shown in table [ tbl - xtail ] , there is also a factor of two difference between the temperatures of the simulated and observed x - ray tails ; however , this is most likely due to the different ways in which this quantity is determined in simulations as compared to observations . we use luminosity - weighted temperatures , which tend to be higher than spectroscopic temperatures when there is a range of gas temperatures ( see mazzotta et al . sun et al . ( 2010 ) discuss how the spectral fitting of the iron - l hump biases their temperatures low if there are significant emission components at _ _ k__t = 0.4 - 2 kev , which is certainly the case in our simulation and in the tail of eso 137 - 001 ( sun et al . 2010 ; sivanandam et al . therefore , the agreement is probably considerably better than indicated in table [ tbl - xtail ] . in this section , we examine what lights up an x - ray bright tail , and explain why some observed tails , like eso 137 - 001 , exhibit x - ray emission , while others do not . in figure [ fig : rhot ] we show the mass - weighted distribution of density and temperature of gas in the wake that originated from the galaxy from our t3vl run ( left ) and from the @xmath26 k run from tb10 using the corrected cooling curve ( right ) . the plots include all of the gas located between 10 kpc and 240 kpc above the disk that has at least 25% of it s mass originating in the galaxy ( as determined by the tracer fraction ) . we choose to highlight these two cases because the icm pressure is the only difference between the two simulations ( the thermal pressures differ by a factor of 15 ) . as discussed in more detail in tb10 , the ( @xmath56 k ) gas in the wake is largely in pressure equilibrium and so falls roughly along a line of constant pressure . the impact of the higher icm pressure can be seen as a shift to higher density and temperature in the left panel . + in red we also plot two contours of constant luminosity per mass ( or emissivity per density ) . the lower contour is at 10@xmath57 erg s@xmath3 g@xmath3 . if the minimum observable x - ray surface brightness is 10@xmath58 erg s@xmath3 @xmath8 , then in order for x - ray emission to reach this level , there must be a sufficient amount of gas at or above the red contour . more precisely , we need a column density of hot gas of 10@xmath59 @xmath8 in order to produce observable emission ( this corresponds to about 10@xmath46 m@xmath10 along a single line of sight through our 38 pc @xmath6 38 pc cells ) . in general , only the colder gas ( t @xmath60 10@xmath46 k ) in the tail has these high surface densities ( 10@xmath59 @xmath8 ) , so we also plot an emissivity line which only requires a surface density of 10@xmath7 @xmath8 in order to be observable ( the upper 10@xmath3 erg s@xmath3 g@xmath3 contour ) . gas that is hot enough to emit x - rays ( hotter than @xmath57 @xmath6 10@xmath47 k ) has this lower surface density in the tail ( 10@xmath7 @xmath8 ) . this figure shows that gas at higher densities and lower temperatures than the icm ( but above @xmath5 10@xmath40 k ) will be emitting the most strongly in x - rays . as galactic gas is stripped it either cools into clouds ( @xmath61 k ) or is compressed to the icm pressure and begins to mix with icm gas . while the tail gas is at the high icm pressure but before it is completely mixed with the icm it will be x - ray bright . the mixing occurs along the line of constant pressure seen in figure [ fig : rhot ] . the separation between cold clouds and x - ray emitting gas is seen clearly in the left panel of figure [ fig : slices ] , which shows a thin slice from a detailed section above the disk . the cold clouds are black in this figure , indicating no x - ray emission , while the x - ray emitting gas is not confined to regions close to the dense clouds . most of the x - ray bright cells in our simulation have between 70% and 90% of their gas originating from the galaxy . in the lower left panel of figure [ fig : slices ] we show the gas temperature , which when compared with the x - ray slice again highlights that while some mixing and radiative cooling can enhance the x - ray emission , but too much lowers the density of the hot gas to the point where the x - ray emissivity is low . the x - ray bright gas may have either been stripped as hot gas from the disk and slowly mixed , or stripped from the dense clouds in the tail and mixed into the icm . next , we turn to h@xmath1 emission , shown in figure [ fig : haproj ] . the minimum observable surface brightness that we adopt for these maps is 2 @xmath6 10@xmath62 erg s@xmath3 @xmath8 arcsec@xmath57 ( see sun et al . ( 2007 ) and references therein ) . as described earlier , we use cloudy to determine the h@xmath1 emissivity given a gas temperature and density . we find , as shown in figure [ fig : haproj ] , highly structured , long tails of h@xmath1 emission . note that we do not include uv radiation from star formation or agn ( except from the metagalactic background , as described in section [ sec : projection ] ) . figure [ fig : slices ] shows that h@xmath1 emission peaks around the edges of cold clouds , which can be seen by comparing the upper right panel of h@xmath1 emission with the lower right panel showing gas surface density . the @xmath63 k and @xmath26 k runs show a similar amount of h@xmath1 emission . this is because , while the minimum temperature affects the temperature in the central regions of the clouds , it does not strongly affect the cloud edges in the simulation , whose characteristics are more determined by the interaction between the cloud and the icm . we find that changing the cloud size parameter in our cloudy run has only a small effect on the total h@xmath1 flux ( less than 10% in all three runs ) . this is because most of our emission is produced by collisional processes rather than photoionization , and so is mostly dependent on the gas temperature , not the optical depth to ionizing photons ( recall that we do include star formation in the simulation and so do not model hii regions within the tail ) . c | c | c | c run or & _ l @xmath6 w _ & f@xmath64 & f@xmath64 corrected@xmath51 + observation & ( kpc @xmath6 kpc ) & ( erg s@xmath3 @xmath8 ) & ( erg s@xmath3 @xmath8 ) + t80vh & 67 @xmath6 27 & 75.8 & 2.23 + t3vh & 65 @xmath6 29 & 75.9 & 2.00 + t3vl & 80 @xmath6 30 & 97.9 & 1.96 + sun et al . ( 2007 ) & @xmath540 @xmath6 6 & 4.4 & 4.4 + because we do not include star formation , we can not compare our h@xmath1 emission to the 33 h@xmath0 regions seen by sun et al . we do compare the total flux from our tail to the observed diffuse h@xmath1 emission in table [ tbl - hatail ] . again , the volume of our diffuse tail is much larger than that observed by sun et al . ( 2007 ) , and we show the corrected h@xmath1 flux by dividing by the volume ratio in the table . the difference in tail widths is from the difference in galaxy sizes , while the length of the observed tail is the minimum length of the diffuse emission because there is a bright star in the field ( sun et al . 2007 ) . when we take the different volumes of the tail into account , our simulated h@xmath1 flux is less than that observed from the tail of eso 137 - 001 , but in all three cases , the simulated h@xmath1 flux is within a factor of 2.5 of the observed flux . there are a number of possible explanations for our slightly lower predicted h@xmath1 flux , including the possibility that some unresolved h@xmath0 regions are counted as diffuse flux in the observations . other heating sources such as thermal conduction an effect we do not include in the simulations could give rise to more h@xmath1 flux than we see in our simulations . we also find that numerical resolution plays a role in the total h@xmath1 emission , as we will discuss in section [ sec - resolution ] . in this section we consider h@xmath0 column density , comparing projections of our simulations to observations . in figure [ fig : hiproj ] we show the h@xmath0 column density at the best resolution of our simulation . as discussed in section [ sec : projection ] , we use cloudy to determine the neutral fraction given a temperature and density ( with the assumed metagalactic uv flux ) and then apply that value in our projection routine . in figure [ fig : atcav01 ] we only show a projection comparable to the observations performed by vollmer et al . ( 2001 ) , using a resolution of 30 " and a minimum column density of 2 @xmath6 10@xmath7 @xmath8 . we also correct for the difference in disk sizes by dividing our column densities by a factor of 3 ( the ratio of x - ray tail diameters ) . only the tail of t3vl would have been observed by vollmer et al . this is because in the slower velocity case there is a smaller velocity difference between the clouds and the icm wind and the icm is slighty less dense ( 83% of the icm density in the higher velocity cases ) , which results in less cloud ablation and more high density gas ( both a slightly higher maximum density of gas and slightly more gas at any particular density above @xmath65 @xmath20 ) . this difference between the non - detection by vollmer et al . ( 2001c ) and our prediction that t3vl would be detected implies that eso 137 - 001 is most likely moving more quickly through the icm than 1413 km s@xmath3 . the h@xmath0 column densities in t3vh and t80vh are within a factor of 3 and 1.3 respectively below the maximum column density as determined by the non - detection of vollmer et al . ( 2001 ) . figure [ fig : slices ] clearly shows that bright h@xmath1 emission is produced only at the edges of dense neutral clouds . this spatial correspondence between neutral and h@xmath1 emitting gas agrees with the observations of sivanandam et al . ( 2009 ) , who found molecular hydrogen in the tail to the farthest distance they could search20 kpc . we predict that with a deeper observation h@xmath0 will be observed to at least 40 kpc ( the length of the observed h@xmath1 tail ) , and likely even farther ( our shortest h@xmath0 tail is 65 kpc in t3vh ) , unless heat conduction is quite efficient . in this section , we comment on the likelihood of finding more x - ray tails . in order for a tail to have observable x - ray emission , it must be in a high pressure icm . we can estimate the pressure necessary to produce bright x - ray emission simply by shifting our mass - weighted distribution of gas until the lowest mass contour lies along the upper 10@xmath3 erg s@xmath3 g@xmath3 contour . we choose this contour because in every simulation we have run , projections of surface density have shown that most of the tail has a column density of at least 10@xmath7 @xmath8 . gas in the tail with higher surface densities tends to be in cold clouds ( t @xmath45 10@xmath46 k ) ( see tb10 ) , while x - rays are emitted by hot ( t @xmath66 10@xmath40 k ) , diffuse gas with lower column densities ( figure [ fig : rhot ] ) . this method results in a minimum icm pressure of 9 @xmath6 10@xmath67 erg @xmath20 . in table [ tbl - clusterrad ] we show the cluster radius at which the icm pressure falls below our minimum value . in general , we calculated the cluster radius using a @xmath68-model and constant temperature from the papers cited in column 3 . there are three exceptions to this . first , the x - ray intensity contours in figure 17 of wang et al . ( 2004 ) denote the highest density icm region ( and are not spherically symmetric ) , which is the only region of a2125 with a high enough density to produce our minimum icm pressure for x - ray bright tails . second , we find the radius of perseus with our minimum icm pressure directly from figure 9 in ettori et al . finally , we use the entropy measurements of cavagnolo et al . ( 2009 ) to find that as close as 100 kpc from m87 the icm pressure is below 9 @xmath6 10@xmath67 erg @xmath20 . note that these are first estimates generally using spherically symmetric cluster profiles , which oversimplify the structure of the icm . we can now comment on whether observed x - ray tails are in high pressure icms ( defined here as at or above 9 @xmath6 10@xmath67 dyn @xmath8 ) . the two x - ray tails in a3627 , eso 137 - 001 and eso 137 - 002 , are both within the high pressure icm ( sun et al . 2007 ; sun et al . . however , sun et al . ( 2010 ) find that using their spectroscopic temperatures , the tail gas is over - pressured with respect to the icm . this might indicate that the spectroscopic temperature does not correctly model the tail temperature . we find that turbulent pressure is not strong enough to greatly increase the gas pressure in the tail ( figure [ fig : rhot ] and tb10 ) . c153 is near the x - ray peak of a2125 ( wang et al . ugc 6697 in a1367 is at least 450 kpc from the x - ray peak of the cluster , outside of our calculated high - pressure radius . however , it is near an infalling subcluster and in a higher - density icm than predicted using the @xmath68-model centered on the x - ray peak of a1367 . using the fit to the subcluster by donnelly et al . ( 1998 ) , sun & vikhlinin ( 2005 ) calculated the surrounding pressure to be 7.9 @xmath6 10@xmath67 dyn @xmath8 , very close to our minimum pressure for observable x - ray emission . c | c | c cluster & outer radius ( kpc ) & reference + a3627 & 250 _ h@xmath69 _ & bohringer et al . ( 1996 ) ; + & & sun et al . ( 2010 ) + a2125 & 28.5 - 89 _ h@xmath70 _ & wang et al . ( 2004 ) + a1367 & 274 _ h@xmath69 _ & mohr et al . ( 1999 ) + cl 0024 + 0016 & 250 _ h@xmath71 _ & zhang et al . ( 2005 ) + coma & 613 _ h@xmath69 _ & briel et al . ( 1992 ) + perseus & 2000 _ h@xmath69 _ & ettori et al . ( 1998 ) + virgo ( m87 ) & @xmath45 100 _ h@xmath71 _ & cavagnolo et al . ( 2009 ) + heat conduction , which we do not include in these simulations , could be important for the survival of cool clouds in the icm and h@xmath1 emission ; however , it can be suppressed by magnetic fields ( e.g. vollmer et al . if it is an efficient way to transport heat from the icm to cold , stripped gas , then the survival time of h@xmath0 clouds would be less than predicted in this paper , and the length of the tails would be shorter . we can estimate the efficiency of heat conduction by comparing an analytic calculation of the evaporation time of the most dense clouds in our simulations to the length of time we expect clouds have survived in order to produce the observations of eso 137 - 001 . first , we estimate the evaporation time for a typical cloud if heat conduction is not suppressed , and we will define this calculated evaporation time as the time for cloud evaporation if heat conduction is 100% efficient . we follow cowie & mckee ( 1977 ) , as in vollmer et al . ( 2001 ) . in our clouds , we find that the mean free path for ions is comparable to or greater than the temperature scale length , so we need to use the saturated heat flux equations . evaporation time is proportional to @xmath72 @xmath73 , where @xmath74 is the conduction efficiency relative to spitzer . solving for the evaporation time for each of our three runs , we find that using a cloud radius of 100 pc , and the maximum gas density in our tails at the time of our comparison , the evaporation times of our three runs are @xmath75 myr for t80vh , @xmath76 myr for t3vh , and @xmath77 myr for t3vl . we choose to use the highest density found in our tails because we want to calculate the longest plausible evaporation time in order to find the most conservative estimates for the maximum efficiency of heat conduction . the @xmath78 k runs have a maximum density in their tails of 2 @xmath6 10@xmath79 g @xmath20 and t80vh has a maximum density of 10@xmath79 g @xmath20 . we have shown that diffuse h@xmath1 emission directly traces neutral clouds ( figure [ fig : slices ] ) , which means that the dense clouds must not be entirely evaporated before they reach 40 kpc above the disk . we are also able to measure the velocity of gas in our tails ( see tb10 for details ) , so can estimate the time it would take for a cloud to reach 40 kpc above the disk . we use generous estimates of 1200 km s@xmath3 for the high velocity cases and 900 km s@xmath3 for the lower velocity run in order to calculate the shortest time it would take these clouds to reach 40 kpc above the disk ( which will maximize the value we find for the efficiency of heat conduction ) . therefore , the efficiency of heat conduction must be less than 24% ( t3vl and t3vh ) , or 12%(t80vh ) . once there is a deep observation of the h@xmath0 tail , we will be able to compare the length of eso 137 - 001 s tail to the lengths of our simulated tails to find a _ minimum _ efficiency of heat conduction . to do this we will use a similar argument to the one above ; namely , compare the amount of time a cloud takes to reach its height above the disk to the evaporation time , assuming that heat conduction is responsible for destroying the clouds . it is important to consider our simulations in this calculation , because they show that even without heat conduction , h@xmath0 may not extend along the entire length of the x - ray tail . the simulations also show the limitations of using a simple velocity and distance argument to calculate the length of time a galaxy has been stripped using 900 km s@xmath3 and the length of the h@xmath0 tail we find that the galaxy in t3vl has been stripped for 87 myr , while the actual time after the wind has hit the galaxy is 110 myr . the high velocity cases have an even larger discrepancy between the actual stripping time and the time calculated using the h@xmath0 tail length . despite these caveats , we can make a very rough first estimate using figure [ fig : atcav01 ] ( t3vl ) and the non - detection result of vollmer et al . the h@xmath0 in our smoothed projection begins about 50 kpc above the disk . if the non - detection of vollmer et al . ( 2001 ) means that there are no neutral clouds at this height above the disk , then we can calculate a minimum efficiency for heat conduction , which is 18.5% . however , as we discussed above , we expect that a deeper observation will find h@xmath0 beyond this height above the disk . as noted earlier , we used two different values for our radiative cooling floor ( 8000 k and 300 k ) in order to explore in a simple way the potential impact of processes which we do not include in the simulation . we discuss the physical motivations for the two cooling floors in tb10 . we find that the change in the minimum temperature makes only a relatively minor change in the morphology of the flow , and does nt significantly change the resulting length of the tail . this also translates into only a relatively small difference in the predicted observables , with changes of less than 30% in both x - ray and h@xmath1 luminosities . k run predicted lower h@xmath1 emission by more than an order of magnitude . this incorrect conclusion was reached because of the cooling curve error for that run discussed in section [ sec - methodology ] . ] the biggest difference is in the survival of h@xmath0 clouds , with @xmath26 k predicting longer lived clouds . still , the impact on h@xmath0 observations is quite small . the ratios of the three observables is also quite constant , generally to within 30% , as can be see from an inspection of the right two panels of figures [ fig : xrayproj ] , [ fig : haproj ] , and [ fig : hiproj ] , and from tables [ tbl - xtail ] and [ tbl - hatail ] . resolution is most likely to affect the survival and structure of our dense clouds in the tail . the most direct results would be different amounts of neutral gas and h@xmath1 emission . a number of examinations of the survival of clouds with a variety of physics included have been performed . mellema et al . ( 2002 ) and yirak et al . ( 2009 ) include radiative cooling . fragile et al . ( 2004 ) also discuss how including self - gravity increases the lifetime of clouds . nakamura et al . ( 2006 ) discuss the impact of using smooth cloud boundaries on the growth of instabilities . they ( and yirak et al . 2009 ) find that a low density gradient results in slower growth of instabilities , which can retard cloud destruction . our most dense clouds have an analytically calculated destruction timescale due to turbulent viscous stripping ( using eq . ( 22 ) in nulsen 1982 ) of more than 1 gyr , so resolution should not have a large impact over the timescales we consider in these simulations . we use the same cloud parameters as in the evaporation time calculation , although even with an order of magnitude lower density clouds ( @xmath5 10@xmath80 g @xmath20 ) , the destruction timescale is still about 200 myr , which is much longer than the time at which we make our projections . we use a relative velocity difference of 400 km s@xmath3 ( although we do not show velocity plots in this paper , see tb10 for a detailed discussion of the tail velocity ) . however , lower density clouds in our simulated tails cool and are compressed by the icm , which may instead be destroyed by the icm wind if we had better resolution that resulted in a steeper density gradient at the cloud edge . although we do not perform a detailed resolution study of the runs in this paper , we do compare t3vl to a run with only 5 allowed levels of refinement , to a minimum cell size of 76 pc , a factor of two worse in resolution . we compare outputs with the same amount of gas stripped from the galaxy . the total x - ray luminosity of the lower resolution tail is @xmath590% of the luminosity of t3vl ( i.e. only a 10% change ) , while the total h@xmath1 flux is only 28% of t3vl . the total hi flux is also decreased by a similar amount ( to 33% of the value in t3vl ) . for both resolutions , there is a good correspondence between the relative hi and h@xmath1 level and morphology ; therefore , we argue that the ratio of hi to h@xmath1 is more robust than the absolute level of either . both the small discrepancy in the x - ray luminosity and larger discrepancy in the h@xmath1 flux can be explained by considering what gas is producing the emission . x - ray emission is produced by gas that is mixed with the icm and is not localized near the dense clouds in the tail , and so is not very dependent on high resolution . one explanation for the slightly lower x - ray luminosity is that mixing happens more quickly and the gas is heated out of the x - ray bright regime . unlike the diffuse nature of the x - ray emitting gas , h@xmath1 emission occurs at the edges of clouds . we find that in projection the range of h@xmath1 intensities is the same as t3vl , meaning that the different resolution element size does not strongly affect the density and temperature at the edges of the dense clouds ( and therefore does not strongly affect the h@xmath1 emission ) . the main difference is that there are fewer dense clouds in the less - resolved wind . in fact , the total h@xmath0 column density in the low resolution tail is about 30% of the total h@xmath0 column density in t3vl very similar to the h@xmath1 flux fraction . in projection , there are about half as many pixels with h@xmath0 column densities over 10@xmath81 @xmath8 . since we expect the total h@xmath0 column density to also depend on the number of clouds along the line of sight of the projection , we find that there should be roughly 26% as many clouds ( by simply squaring the 51% we find in the projection plane ) . of course , clouds are more than a single pixel , so this is a rough approximation . however , this indicates that the amount of h@xmath1 emission closely follows the amount of h@xmath0 column density , and likely the number of h@xmath0 clouds . there are fewer h@xmath0 clouds in the low resolution run because with lower resolution the maximum density is lower and therefore the clouds are destroyed and mixed more quickly into the icm . deep , high resolution observations in h@xmath0 will allow us to determine how many and for how long dense clouds survive , which will point to one of these mixing scenarios . we have run detailed galaxy simulations including radiative cooling and made comparisons to the observed tail of eso 137 - 001 to understand the physical mechanisms at work in the icm . we compare three cases in which we vary our cooling floor between 8,000 k or 300 k and the icm parameters as shown in table [ tbl - runs ] . our main conclusions are as follows : \1 ) the x - ray luminosity of our simulated tails are an excellent match to the x - ray luminosity of the tail of eso 137 - 001 . this suggests that we are correctly modeling the phase distribution of gas in the tail , and that the mixing of the hotter stripped ism ( t @xmath66 10@xmath47 k ) is being accurately modeled in the simulations . \2 ) we find that bright x - ray emission depends upon a high surrounding icm pressure , and find a minimum necessary pressure of 9 @xmath6 10@xmath67 erg @xmath20 . this conclusion agrees well with the local environment in clusters where bright x - ray tails are observed . \4 ) we predict that deeper observations will find h@xmath0 gas to at least 40 kpc above the disk , because diffuse h@xmath1 emission directly traces neutral clouds ( and has been observed to 40 kpc above the disk ) . the observations of molecular hydrogen by sivanandam et al . ( 2009 ) strengthen this prediction . we also conclude that the mismatch between t3vl and vollmer et al . ( 2001 ) indicates that the higher velocity cases better match the observations . \5 ) using the fact that h@xmath1 traces neutral gas and calculating the evaporation times of our simulated clouds ( based on their sizes and densities ) , we calculated a maximum efficiency for heat conduction of 24% ( t3vh and t3vl ) or 12% ( t80vh ) . by modeling a simulation using a high icm pressure , we have shown that x - ray emission can coexist with h@xmath0 and h@xmath1 emission . we have also found that h@xmath0 and h@xmath1 emission spatially coincide because h@xmath1 is mostly produced at the edges of neutral clouds ( figure [ fig : slices ] ) , while x - ray emission is generated in hot , diffuse gas that is mixing with the icm . this is seen by the more even distribution in the tail ( figures [ fig : xrayproj ] and [ fig : slices ] ) , and by the fact that the x - ray tail can be longer than the h@xmath0 and h@xmath1 tails . our excellent agreement with x - ray observations gives us confidence that we are correctly modeling the mixing , cooling and heating rate of x - ray emitting gas . this in turn means that heat conduction is not acting strongly to heat the diffuse gas in the tail , and that small scale turbulence ( below our resolution scale ) is not quickly mixing stripped gas . both of these mechanisms would act to heat the gas in the tail out of the x - ray bright range and therefore lower the total luminosity , which would make our agreement to the observations worse . we can not rule out the possibility that we have less gas mass at higher emissivities than in eso 137 - 001 . we also find excellent agreement between our simulated h@xmath1 flux and observations of diffuse h@xmath1 emission . we robustly conclude that diffuse h@xmath1 emission coincides with h@xmath0 gas , and we find that h@xmath1 emission outlines h@xmath0 clouds in all of our simulations . the agreement between the total h@xmath1 emission in our cases with different cooling floors underscores the fact that the edges of clouds , which are interacting with the icm , emit the most strongly in h@xmath1 , not the central regions of the clouds , which are more likely to have radiatively cooled to the minimum allowed temperature . although our agreement with observations indicates that we may also be correctly modeling the edges of dense clouds , we can not dismiss the possibility that we are not fully resolving the cloud edges . in section [ sec - resolution ] we discuss how lower resolution results in fewer h@xmath0 clouds , and less h@xmath1 emission . therefore , we can not rule out that properties of our simulations that have not converged at our current resolution the number of clouds , the rate of the decline of density at the edge of the cloud and the smallest scale of turbulent heating have combined with the lack of heat conduction in our simulations to result in an accidental , and incorrect , agreement with observations . observations of h@xmath0 in the tail will provide an important check to these results . this work highlights the importance of comparing simulations to detailed , multi - wavelength observations of individual systems . we are able to make predictions about this particular galaxy , such as the existence of h@xmath0 gas in the tail and that its three - dimensional velocity relative to the icm is probably larger than 1413 km s@xmath3 . however , our simulation is not able to make any prediction about why there is a separated tail in eso 137 - 001 . we also do not reproduce the exact surface brightness distribution along the x - ray tail . as we have discussed , our goal was not to reproduce this specific tail . in order to do this , we would recommend modeling a smaller galaxy and matching the inclination angle between the galaxy and the icm wind . using our comparison with the observations of eso 137 - 001 , we also draw more general conclusions about the importance of turbulence and the efficiency of heat conduction in the icm . we conclude that the mixing rate of the hot stripped ism ( t @xmath66 10@xmath47 k ) is well - modeled in our simulations using only adiabatic compression and turbulent mixing down to the resolution of our simulations ( 38 pc ) . we call upon observers to test our predictions of where in clusters tails will be x - ray bright , and to use deep observations to verify the connection between h@xmath1 and h@xmath0 gas . observations of the h@xmath0 tail of eso 137 - 001 can be used to test mixing of cold clouds into the icm in our simulations . we acknowledge support from nsf grants ast-0547823 , ast-0908390 , and ast-1008134 , as well as computational resources from the national center for supercomputing applications , nsf teragrid , and columbia university s hotfoot cluster . we thank jacqueline van gorkom , jeffrey kenney and the referee bernd vollmer for useful discussions , as well as elizabeth tasker for invaluable help setting up the initial conditions .

some tails of ram - pressure stripped galaxies are detected in h@xmath0 , some in h@xmath1 , and some in x - ray ( but never all three so far ) . we use numerical simulations to probe the conditions for the production of x - ray bright tails , demonstrating that the primary requirement is a high pressure intracluster medium ( icm ) . this is because the stripped tail is mostly in pressure equilibrium with the icm , but mixing leaves it with densities and temperatures intermediate between the cold gas in the disk and the hot icm . given a high enough icm pressure , this mixed gas lies in the x - ray bright region of the phase diagram . we compare the simulations to observations of the ram pressure stripped tail of eso 137 - 001 , showing excellent agreement in the total measured x - ray and h@xmath1 emission and non - flaring morphology of the tail , and consistent h@xmath0 measurements . using these comparisons we constrain the level of mixing and efficiency of heat conduction in the intracluster medium ( icm ) .

the array of treatment options available to patients with type 2 diabetes mellitus ( t2 dm ) has increased markedly in recent years , as reflected in recent treatment guidelines.1 current recommendations involve commencing metformin monotherapy if dietary and lifestyle modifications are not sufficient , with the addition of other agents if the patient s glycated hemoglobin ( hba1c ) target is not met after 3 months . available agents include sulfonylureas ( sus ) , thiazolidinediones ( tzds ) , dipeptidyl peptidase-4 ( dpp-4 ) inhibitors , sodium glucose cotransporter 2 ( sglt-2 ) inhibitors , glucagon - like peptide 1 receptor agonists ( glp-1 ras ) , and insulin . triple therapy may be needed if the hba1c target is not reached on dual therapy , with the addition of insulins if required.1 glucose control or homeostasis is the focus of treatment for patients with t2 dm . current guidelines from the american diabetes association ( ada ) and the european association for the study of diabetes ( easd ) recommend a personalized approach to glycemic control rather than a universal goal for all patients ; an hba1c level of 7% is often used as a cutoff point.1,2 despite comprehensive treatment guidelines and the availability of a range of therapeutic options , many patients continue to have poorly controlled diabetes . in the us , 48% of people with diabetes in the national health and nutrition examination surveys ( nhanes ) had an uncontrolled hba1c > 7% between 2007 and 2010,3 with 13% of patients having an hba1c > 9%.4 in an audit of over 2 million patients with diabetes in england and wales , 35% of patients with t2 dm had hba1c > 7.5%.5 these data suggest that , despite the availability of a range of therapeutic options and guidelines , patients may be treated inadequately or are not taking control of their condition effectively , for example , via lack of lifestyle improvements or non - adherence to medication regimens . using data from successive waves of the adelphi real world diabetes disease specific programme ( dsp ) , the aim of these analyses was to assess treatment patterns reported by primary care physicians ( pcps ) and specialists involved in the management of patients with t2 dm and the subsequent impact on levels of glycemic control . key aspects of these analyses were to assess changing t2 dm therapy usage since the launch of newer drug classes ; review the role of polypharmacy ; identify the trigger point at which physicians introduce insulin therapy in patients with t2 dm ; review any changes in time to insulin introduction ; and analyze if any identified changes in treatment have ultimately affected hba1c levels over an extended period in this patient population . data were drawn from successive waves of the diabetes dsp conducted between 2000 and 2015 in the us and eu5 ( france , germany , italy , spain , and the uk ) . these were prospective , cross - sectional surveys of physicians and their patients presenting in a real - world clinical setting . although not longitudinal in nature , each wave provides an independent snapshot of cross - sectional data , which can be used to explore patterns over time . dsps are large , multinational surveys conducted in clinical practice that describe current disease management , disease - burden impact , and associated treatment effects ( clinical and physician - perceived ) . the survey methodology is designed to facilitate collection of up - to - date data from the following three key sources of information : physician face - to - face interviews , physician - reported workload questionnaires , and patient record forms . a complete description of the methods of the survey has been previously published.6 using a check box , patients provided informed consent for use of their anonymized and aggregated data for research and publication in scientific journals . data were collected in such a way that patients and physicians could not be identified directly ; all data were aggregated and de - identified before receipt , and as a result , data collection was undertaken in line with european pharmaceutical marketing research association guidelines and as such it does not require ethics committee approval . each survey was performed in full accordance with relevant legislation at the time of data collection , including the us health insurance portability and accountability act 1996,7 the european pharmaceutical marketing research association guidelines,8 and health information technology for economic and clinical health act legislation.9 for each dsp wave , physicians were eligible to participate in this research if they were personally responsible for treatment decisions and management of patients with t2 dm . inclusion criteria for patients were aged 18 years , a physician - confirmed diagnosis of t2 dm , receiving antidiabetic non - insulin therapy ( with or without insulin regimens ) , and consulting the physician on the day of assessment . each wave of data collection was independent of the others , ensuring the same physicians and patients were not included year on year . of particular importance to our study objective was the question included from 2004 onward that specifically asked physicians what hba1c level would prompt initiation of insulin therapy . irrespective of which patients were recruited for the survey , physicians recorded the total number of patients with t2 dm consulting per day who were being managed with the following treatment approaches : 1 ) diet and exercise only ; 2 ) non - insulin drug treatment only ; 3 ) non - insulin drug treatment plus insulin ; and 4 ) insulin only . physicians were then instructed to complete a patient record form for the next 10 consecutive consulting patients with a physician - confirmed diagnosis of t2 dm and receiving prescribed antidiabetic therapy ( with or without insulin ) , regardless of the reason for the consultation . the physician - reported forms reflected physicians knowledge about their treatment decisions and assessment of health status in patients seeking routine care , including information on patients demographics , clinical assessments , clinical outcomes , diabetes medication use , and history . market updates from year to year necessitated minor amendments to some questions ( refer table s1 for specific questions administered in each wave ) . it should be noted that as each survey was designed to facilitate understanding of real - world clinical practice , physicians could only report on data they had to hand at the time of the consultation . therefore , this represents the evidence they had when making any clinical treatment and other management decisions at that consultation . continuous numerical variables were described by their mean . as the time from diagnosis of t2 dm to the survey date was different in each patient within each wave , the time to initiation of insulin was compared against the year the patient was diagnosed , rather than the survey year in which the patient was included . for example , a patient recruited in 2015 diagnosed with t2 dm 5 years earlier was considered the same as a patient recruited in 2011 diagnosed for 1 year , as their diabetes management would have started in the same year . survival analysis was used to analyze the time from diagnosis to the first insulin regimen . this method was chosen as patients who had not received any insulin regimen by the time of the survey could be included ; therefore , a patient s time from diagnosis to the point of data collection was used even if a patient had not yet received insulin , as they could potentially receive insulin at some point in the future . meier failure curves were plotted by time of diagnosis , where failure in this analytical setting infers the initiation of insulin . a log - rank test was used to assess significant differences in the time taken for patients to receive insulin . for each dsp wave , physicians were eligible to participate in this research if they were personally responsible for treatment decisions and management of patients with t2 dm . inclusion criteria for patients were aged 18 years , a physician - confirmed diagnosis of t2 dm , receiving antidiabetic non - insulin therapy ( with or without insulin regimens ) , and consulting the physician on the day of assessment . each wave of data collection was independent of the others , ensuring the same physicians and patients were not included year on year . of particular importance to our study objective was the question included from 2004 onward that specifically asked physicians what hba1c level would prompt initiation of insulin therapy . irrespective of which patients were recruited for the survey , physicians recorded the total number of patients with t2 dm consulting per day who were being managed with the following treatment approaches : 1 ) diet and exercise only ; 2 ) non - insulin drug treatment only ; 3 ) non - insulin drug treatment plus insulin ; and 4 ) insulin only . physicians were then instructed to complete a patient record form for the next 10 consecutive consulting patients with a physician - confirmed diagnosis of t2 dm and receiving prescribed antidiabetic therapy ( with or without insulin ) , regardless of the reason for the consultation . the physician - reported forms reflected physicians knowledge about their treatment decisions and assessment of health status in patients seeking routine care , including information on patients demographics , clinical assessments , clinical outcomes , diabetes medication use , and history . market updates from year to year necessitated minor amendments to some questions ( refer table s1 for specific questions administered in each wave ) . it should be noted that as each survey was designed to facilitate understanding of real - world clinical practice , physicians could only report on data they had to hand at the time of the consultation . therefore , this represents the evidence they had when making any clinical treatment and other management decisions at that consultation . continuous numerical variables were described by their mean . as the time from diagnosis of t2 dm to the survey date was different in each patient within each wave , the time to initiation of insulin was compared against the year the patient was diagnosed , rather than the survey year in which the patient was included . for example , a patient recruited in 2015 diagnosed with t2 dm 5 years earlier was considered the same as a patient recruited in 2011 diagnosed for 1 year , as their diabetes management would have started in the same year . survival analysis was used to analyze the time from diagnosis to the first insulin regimen . this method was chosen as patients who had not received any insulin regimen by the time of the survey could be included ; therefore , a patient s time from diagnosis to the point of data collection was used even if a patient had not yet received insulin , as they could potentially receive insulin at some point in the future . meier failure curves were plotted by time of diagnosis , where failure in this analytical setting infers the initiation of insulin . a log - rank test was used to assess significant differences in the time taken for patients to receive insulin . a total of 3,555 specialists and 5,109 pcps participated in the 12 dsp waves conducted between 2000 and 2015 . a total of 88,681 patients with t2 dm were counted via the 5-day workload page , providing the holistic prescribed and non - prescribed antidiabetic cohort ; 70,657 patients with t2 dm were recruited via the physician - reported questionnaires providing the prescribed antidiabetic therapy ( non - insulin therapy with or without insulin ) cohort ( figure 1 ) . baseline characteristics of patients treated by pcps and specialists were generally consistent over time ( table 1 ) . no changes were apparent in mean age at diagnosis , current age , and body mass index . however , a slight increase was observed in the mean number of antidiabetic agents prescribed . this was more pronounced among specialists , who prescribed an average of 1.6 agents per patient in 2000 , increasing to 2.1 per patient in 2015 . this increase was greatest between 2000 and 2006 , with the mean number of antidiabetic drugs remaining relatively static since 2006 . in order to obtain an overview of treatment received by patients with diabetes , pcps and specialists were asked to record what therapies their patients were receiving : diet and exercise only ; non - insulin drug treatment only ; non - insulin drugs plus insulin ; and insulin only . as shown in figure s1 insulin - only regimens and diet and exercise only played a minor role , being used in < 20% and < 10% of patients , respectively , with these proportions remaining relatively unchanged over time . both pcps and specialists have consistently reported prescribing a higher proportion of both non - insulin - only regimens and especially among specialists non - insulin plus insulin regimens , and this generally remained static between 2004 and 2015 . owing to these therapy dynamics , subsequent analyses excluded patients on insulin - only regimens and diet and exercise only . the range of individual regimens used for the treatment of patients with t2 dm has changed greatly since 2000 , as demonstrated by the introduction of new agents from 2006 onward ( figure 2 ) . metformin monotherapy was most commonly prescribed by pcps , increasing to a peak of 44% of patients in 2012 before dropping to 36% in 2015 . the use of non - insulin - only combinations containing the new drug classes is derived from the addition of metformin plus dpp-4 inhibitor usage to all other non - insulin regimens containing single or combined use of dpp-4 inhibitors , sglt-2 inhibitors , and glp-1 ras . non - insulin - only combination use of these newer drug classes increased among pcps from 4% of patients in 2008 to 33% in 2015 , in particular , metformin plus dpp-4 inhibitors predominantly in free form but also included fixed - dose combinations . this pattern was observed to a greater extent among specialists , where the use of the newer non - insulin - only classes , alone or in combination , increased from 1% of patients in 2006 to 43% in 2015 . specialist use of regimens containing non - insulin drugs plus insulin increased over the time period , being prescribed for 16% of patients in 2000 and 29% of patients in 2015 , whereas pcp use of these regimens remained relatively static . the proportion of physicians stating they would introduce insulin at hba1c < 8% decreased from 24% of pcps and 34% of specialists in 2004 to 7% for both pcps and specialists in 2015 ( figure s2 ) . a corresponding increase in the proportion of physicians waiting until hba1c was 9% was observed over this time period , from 36% of pcps and 24% of specialists in 2004 to 42% of pcps and 39% of specialists in 2015 . in line with physicians perceptions of insulin being initiated at higher hba1c levels , mean actual hba1c level at the time of insulin initiation increased over the study period , as shown in figure s3 , with the most pronounced increase being observed between 2011 and 2014 for pcps ( 2011 : 8.7% ; 2014 : 9% ) and between 2011 and 2015 for specialists ( 2011 : 8.8% ; 2015 : 9.7% ) . figure 3 shows time to insulin initiation , with patients receiving insulin significantly sooner after diagnosis in more recent years ( p<0.001 ; log - rank test ) . an overall trend toward a shorter time to insulin initiation was observed ; this was most pronounced among specialists . for example , a specialist - treated patient diagnosed before 1999 had an 8% likelihood of receiving insulin within the first 5 years after diagnosis compared with 17% for a patient diagnosed between 2004 and 2007 and 19% for a patient diagnosed between 2008 and 2011 . the proportion of patients with hba1c < 7% , the goal recommended by many guidelines , is shown in figure 4 . in 2015 , 50% of pcp - treated patients were likely to have controlled diabetes compared with 36% of specialist - treated patients . as expected , specialists treated a higher proportion of patients with hba1c > 9% compared with pcps . although improvements were seen in both groups of patients between 2000 and 2015 , the majority of this progress was achieved between 2000 and 2008 ; glucose control has improved little since then . a total of 3,555 specialists and 5,109 pcps participated in the 12 dsp waves conducted between 2000 and 2015 . a total of 88,681 patients with t2 dm were counted via the 5-day workload page , providing the holistic prescribed and non - prescribed antidiabetic cohort ; 70,657 patients with t2 dm were recruited via the physician - reported questionnaires providing the prescribed antidiabetic therapy ( non - insulin therapy with or without insulin ) cohort ( figure 1 ) . baseline characteristics of patients treated by pcps and specialists were generally consistent over time ( table 1 ) . no changes were apparent in mean age at diagnosis , current age , and body mass index . however , a slight increase was observed in the mean number of antidiabetic agents prescribed . this was more pronounced among specialists , who prescribed an average of 1.6 agents per patient in 2000 , increasing to 2.1 per patient in 2015 . this increase was greatest between 2000 and 2006 , with the mean number of antidiabetic drugs remaining relatively static since 2006 . in order to obtain an overview of treatment received by patients with diabetes , pcps and specialists were asked to record what therapies their patients were receiving : diet and exercise only ; non - insulin drug treatment only ; non - insulin drugs plus insulin ; and insulin only . as shown in figure s1 insulin - only regimens and diet and exercise only played a minor role , being used in < 20% and < 10% of patients , respectively , with these proportions remaining relatively unchanged over time . both pcps and specialists have consistently reported prescribing a higher proportion of both non - insulin - only regimens and especially among specialists non - insulin plus insulin regimens , and this generally remained static between 2004 and 2015 . owing to these therapy dynamics , subsequent analyses excluded patients on insulin - only regimens and diet and exercise only . the range of individual regimens used for the treatment of patients with t2 dm has changed greatly since 2000 , as demonstrated by the introduction of new agents from 2006 onward ( figure 2 ) . metformin monotherapy was most commonly prescribed by pcps , increasing to a peak of 44% of patients in 2012 before dropping to 36% in 2015 . the use of non - insulin - only combinations containing the new drug classes is derived from the addition of metformin plus dpp-4 inhibitor usage to all other non - insulin regimens containing single or combined use of dpp-4 inhibitors , sglt-2 inhibitors , and glp-1 ras . non - insulin - only combination use of these newer drug classes increased among pcps from 4% of patients in 2008 to 33% in 2015 , in particular , metformin plus dpp-4 inhibitors predominantly in free form but also included fixed - dose combinations . this pattern was observed to a greater extent among specialists , where the use of the newer non - insulin - only classes , alone or in combination , increased from 1% of patients in 2006 to 43% in 2015 . specialist use of regimens containing non - insulin drugs plus insulin increased over the time period , being prescribed for 16% of patients in 2000 and 29% of patients in 2015 , whereas pcp use of these regimens remained relatively static . the proportion of physicians stating they would introduce insulin at hba1c < 8% decreased from 24% of pcps and 34% of specialists in 2004 to 7% for both pcps and specialists in 2015 ( figure s2 ) . a corresponding increase in the proportion of physicians waiting until hba1c was 9% was observed over this time period , from 36% of pcps and 24% of specialists in 2004 to 42% of pcps and 39% of specialists in 2015 . in line with physicians perceptions of insulin being initiated at higher hba1c levels , mean actual hba1c level at the time of insulin initiation increased over the study period , as shown in figure s3 , with the most pronounced increase being observed between 2011 and 2014 for pcps ( 2011 : 8.7% ; 2014 : 9% ) and between 2011 and 2015 for specialists ( 2011 : 8.8% ; 2015 : 9.7% ) . figure 3 shows time to insulin initiation , with patients receiving insulin significantly sooner after diagnosis in more recent years ( p<0.001 ; log - rank test ) . an overall trend toward a shorter time to insulin initiation was observed ; this was most pronounced among specialists . for example , a specialist - treated patient diagnosed before 1999 had an 8% likelihood of receiving insulin within the first 5 years after diagnosis compared with 17% for a patient diagnosed between 2004 and 2007 and 19% for a patient diagnosed between 2008 and 2011 . the proportion of patients with hba1c < 7% , the goal recommended by many guidelines , is shown in figure 4 . in 2015 , 50% of pcp - treated patients were likely to have controlled diabetes compared with 36% of specialist - treated patients . as expected , specialists treated a higher proportion of patients with hba1c > 9% compared with pcps . although improvements were seen in both groups of patients between 2000 and 2015 , the majority of this progress was achieved between 2000 and 2008 ; glucose control has improved little since then . real - world data spanning prolonged time intervals provide an opportunity to gain insights into treatment patterns and how they change over time . the diabetes suite of dsp analyses has assessed clinical trends and treatment patterns almost annually since 2000 , providing a real - world view of the changing t2 dm environment over this period . the present analysis of treatment patterns in patients with t2 dm over the period between 2000 and 2015 began with a holistic overview of four main treatment classes : diet and exercise only ; non - insulin drug treatment only ; insulin only ; and insulin plus a non - insulin drug . the most apparent changes over time were an increase in the use of insulin plus an oral non - insulin ( oral antidiabetic agent with or without glp-1 ra ) and a reduction in the use of oral antidiabetic non - insulin agents alone . this is in line with treatment guidelines , which provide clear recommendations on when insulin should be added to oral non - insulin therapy,1,2 and agrees with the notion that physicians do not appear to feel constrained by payer or formulary influences when prescribing antidiabetic therapies.10 examination of drug treatment patterns over this time period revealed that specialist use of non - insulin plus insulin regimens doubled between 2000 and 2006 , whereas pcp use increased only slightly . since 2006 , there have been large increases in the use of the dpp-4 inhibitors , glp-1 ras , and sglt-2 inhibitors by pcps and specialists . this coincided with a decline in the use of regimens containing older agents such as sus , tzds , prandial glucose regulators , and alpha - glucosidase inhibitors . the use of tzds may have been affected by the introduction in 2007 of a black box warning for rosiglitazone;11 this may have resulted in an increase in the use of insulin in 2008 . in their study of prescribing in the uk primary care population , sharma et al12 reported an increase in metformin from 55% of treated patients in 2000 to 84% in 2013 , while prescription of sus decreased from 65% to 41% , results that are in agreement with the findings of this analysis . our analysis also showed that the mean number of antidiabetic drugs per patient increased slightly between 2000 and 2008 , a trend that was more noticeable in patients treated by specialists . interestingly , the mean number of antidiabetic drugs has remained static since 2006 among pcps and increased only slightly among specialists , suggesting that pcps are more likely to switch therapy , while specialists add agents in an effort to achieve glycemic control . among patients treated by specialists , fewer received metformin monotherapy and more received insulin therapy compared with patients treated by pcps ; this is consistent with more advanced disease at the time of referral to the specialist . although we observed increased use of newer agents , use of metformin monotherapy remained relatively static , suggesting no move toward introduction of multiple therapies earlier in the treatment path . between 2010 and 2015 , an increase was observed in the hba1c level at which physicians stated they would initiate insulin . in - line with these perception data , the hba1c level at which insulin was actually initiated also increased . current ada / easd guidelines recommend introducing insulin to the regimen for hba1c levels 10%12%;1 therefore , our findings are suggestive of adherence to guideline recommendations . despite insulin now being initiated at higher hba1c levels than in earlier years , the actual time to insulin initiation decreased over the study period , suggesting that insulin - naive patients are reaching these higher hba1c levels sooner . coupled with our data also showing that patient age at diagnosis has not changed over the survey time period , this would suggest that more patients are reaching the point of needing insulin treatment sooner in their disease progression . a key finding of our research was that , despite the increased range of antidiabetic agents now available , hba1c levels did not appear to be substantially better in 2015 than in 2000 in specialist - treated patients , although a small reduction was observed in patients treated by pcps . this is likely to be a consequence of referral bias , with specialists seeing patients with more advanced , complex disease after failure of more straightforward therapy . in - line with our own findings , the prevalence of patients achieving hba1c < 7% reported in the us nhanes study increased from 43% in the 19881994 report to 57% in nhanes 20032007 report as a result of the availability of newer agents , before falling to 53% in 20072010.3 further research is needed to establish why the development of new and effective antidiabetic agents has not led to better glucose control ; however , as the mean change in hba1c achieved is < 1% for many of the glucose - lowering agents and > 1% for only the sus , glps , and insulins,13 the challenge faced by clinicians is considerable . some limitations of this analysis should be considered . different waves of the diabetes dsp surveys are based on questionnaires and interviews that changed over time depending on market changes , needs , and prescribing environments . this evolution of the dsp facilitates the collection of more timely and relevant data , which can be used to monitor trends in a changing landscape . for example , introduction in recent surveys of a key question such as at what hba1c level would you initiate insulin ? enhances disease management understanding in today s market where newer agents offer pre - insulin options that did not previously exist . information regarding the time from diagnosis to insulin initiation was recorded differently in the various surveys . questions administered in 2011 and 2012 captured this information via a direct question to the physician in each patient form . data collected during 20132015 derived this information via treatment history information , although it must be borne in mind that it is possible that there may be missing information as physicians might not have had access to the complete patient record from diagnosis , particularly if patients changed their physician ( or insurer ) . patients included in the surveys may not reflect the general diabetes population , as patients in these analyses are consulting their physician and represent those who are likely to consult more frequently . despite these limitations , real - world studies play an important part in highlighting areas of concern that are not addressed in clinical trials . patients included in clinical trials represent a small proportion of the consulting population as a result of age restrictions and failure to meet stringent eligibility criteria.14 patients treated in the real - world setting may be less likely to be adherent to medication than those included in clinical trials.15 as a result , data from real - world studies can complement clinical trials and provide insight into the efficacy of interventions in patients commonly seen in clinical practice . treatment choices after metformin monotherapy have increased markedly for patients with t2 dm , as specialists in particular take advantage of the range of antidiabetic agents and insulins now available . the proportion of patients achieving good glucose control ( hba1c < 7% ) increased most between 2000 and 2008 . however , despite the availability of the newer agents and earlier introduction of insulin regimens , no improvement in the proportion of patients achieving hba1c < 7% has been observed since that time . it would seem that further clarification is required to establish which t2 dm treatment pathways should be utilized in individual patient types to achieve improved and sustained glycemic control .

backgrounddespite the availability of a variety of treatments , many patients with type 2 diabetes mellitus ( t2 dm ) are not achieving glucose control . we analyzed successive waves of the adelphi real world diabetes disease specific programmes ( dsps ) to assess treatment patterns reported by primary care physicians ( pcps ) and specialists and the effect of treatment on levels of glucose control.methodsdata were collected between 2000 and 2015 in the us and eu5 ( france , germany , italy , spain , and the uk ) . physicians completed patient record forms for the next 10 patients consulting with t2 dm . key aspects captured were change over time in therapy usage , time to insulin introduction , and glycated hemoglobin ( hba1c ) levels.resultsover 12 dsp waves , 3,555 specialists and 5,109 pcps completed questionnaires for 70,657 patients . treatment patterns changed considerably over time as new agents were introduced . the number of agents prescribed per patient increased over time , as did hba1c levels at which physicians stated they would introduce insulin . the greatest improvements in hba1c levels occurred during 20002008 , with little improvement since 2008.conclusionin this real - world setting , the proportion of patients with t2 dm achieving good glucose control has not increased greatly since 2008 . a better understanding of how to individualize treatment pathways may be required to improve control in these patients .

a 75-year - old woman was admitted to the emergency department with acute right abdominal pain of 2-hour duration . her medical history included a hysterectomy 30 years ago . from several decades ago her vital signs were as follows : blood pressure , 150/75 mmhg ; pulse , 84 beats per minute and regular ; respirations , 20 per minute ; and body temperature , 36.0. clinical examination revealed diffuse pain in the right abdomen with tenderness . urinalysis showed 2 to 4 red cells and 0 to 1 white cells per field under high - power magnification . serum chemical analysis showed a urea level of 26 mg / dl , a creatinine level of 1.5 mg / dl , and a c - reactive protein ( crp ) level of 0.99 mg / dl . after analgesic injection , her pain subsided . with a presumptive diagnosis of acute gastroenteritis , the following day , the patient was admitted to the gastrointestinal department with persistent right abdominal pain . an abdominal computed tomographic ( ct ) scan was performed , which showed a dilated urinary bladder , hydronephroureterosis , and perinephric fluid collection . the patient was referred to our urologists , who recommended insertion of an indwelling foley catheter . because there was no delayed phase on ct , we performed a non - enhanced ct scan immediately . it showed extravasation of radiocontrast from the right upper ureter at the l3 to 4 transverse process level and improved hydronephroureterosis ( fig . after 7 days , antegrade pyelography ( agp ) performed through the nephrostomy catheter showed no extravasation of radiocontrast from the ureter ( fig . a double - j catheter ( 6 f , 24 cm ) was placed in the right ureter . after 2 weeks , the double - j catheter was removed and we subsequently performed a video - urodynamic study . in other words , the patient showed detrusor underactivity and no vesicoureteric reflux ( vur ) . it showed resorption of urinoma in the right peri - renal space and there was neither malignancy nor obstructing lesions . ureteric rupture is rare and can be traumatic or , less commonly , nontraumatic in nature . the most common cause of traumatic ureteric rupture is iatrogenic trauma , followed by penetrating trauma , and occasionally , blunt abdominal trauma . nontraumatic ureteric rupture includes transmitted back pressure from a downstream obstruction caused by ureteric stones , surgical ligature , or an abdominal or pelvic mass . the most common symptoms are sudden , severe , persistent lower abdominal pain with severe peritoneal irritation . another report described massive urinary leakage into the peritoneal cavity , resulting in abdominal compartment syndrome , respiratory distress , and anuria . ct scanning is considered the optimal evaluation for diagnosing ureteric rupture , because of the expected poor resolution of intravenous urography in an unprepared patient . also , one can obtain more accurate information about the location and the size of the urinoma on a ct scan , and the progression of its characteristics can be readily assessed . in this case , we diagnosed ureteric rupture easily by use of a ct scan . in delayed - phase images , many authors have resorted to open surgery earlier for complete management of spontaneous rupture and urinoma . the incidence of late complications , such as ureteric stricture , ureteropelvic stenosis , or peri - ureteric fibrosis remains unknown . believe that in urinary extravasation , treatment should be supportive initially ( i.e. , careful observation and analgesics ) . persistent obstruction and severe pain , infection , and failing renal function although nontraumatic perforation of the ureter is relatively benign , it may predispose the patient to perinephric abscess . reported successful treatment of ureteric rupture by the insertion of a double - j ureteric stent under fluoroscopy . they achieved unobstructed urinary outflow , healing of the perforation , and stabilization and gradual absorption of the urinoma . in the modern era , open surgical intervention is rarely indicated , because minimally invasive techniques such as percutaneous drainage can be used to manage complications . in our case , there was no evidence of factors that cause ureteric rupture other than urinary retention . urinary retention may inhibit urinary flow to the bladder and result in high intraureteric pressure . as intraureteric pressure rises , the ureteric wall fails to withstand the pressure and becomes ruptured . urologists should be aware of the possibility of ureteric rupture in the differential diagnosis of an acute abdomen , particularly in patients with urinary retention . management of these patients should include minimally invasive techniques accompanied by active management of urinary retention .

perforation of the ureter is a rare condition that causes a series of problems including retroperitoneal urinoma , urosepsis , abscess formation , infection , and subsequent renal impairment . there are causative factors that induce ureteric rupture , including malignancy , urinary calculi , idiopathic retroperitoneal fibrosis , recent iatrogenic manipulation , external trauma , degenerative kidney conditions , urography with external compression , and spontaneous causes . we report a rare case of ureteric rupture caused by urinary retention . the patient was treated with temporary percutaneous drainage and antibiotics . the present case illustrates that urinary retention can induce not only bladder rupture , but also ureteric rupture . it is thus of paramount importance to effectively manage patients with voiding problems .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Ninth Circuit Court of Appeals Reorganization Act of 2003''. SEC. 2. NUMBER AND COMPOSITION OF CIRCUITS. Section 41 of title 28, United States Code, is amended-- (1) in the matter before the table, by striking ``thirteen'' and inserting ``fourteen''; and (2) in the table-- (A) by striking the item relating to the ninth circuit and inserting the following: ``Ninth................................ California, Nevada.''; (B) by striking the item relating to the tenth circuit and inserting the following: ``Tenth................................ Arizona, Colorado, Kansas, New Mexico, Oklahoma, Utah, Wyoming.''; (C) by inserting between the last 2 items the following: ``Twelfth.............................. Alaska, Guam, Hawaii, Idaho, Montana, Northern Mariana Islands, Oregon, Washington.''. SEC. 3. NUMBER OF CIRCUIT JUDGES. (a) The table in section 44(a) of title 28, United States Code, is amended-- (1) by striking the item relating to the ninth circuit and inserting the following: ``Ninth................................................ 20''; and (2) by inserting between the last 2 items the following: ``Twelfth.............................................. 8''. (b) As of February 1, 2005, the table in section 44(a) of title 28, United States Code is further amended-- (1) by striking the item amended pursuant to subsection (a)(1) and inserting the following: ``Ninth................................................ 25''; (2) by striking the item amended pursuant to subsection (a)(2) and inserting: ``Twelfth.............................................. 10''; and (3) by striking the item relating to the tenth circuit and inserting the following: ``Tenth................................................ 14''. SEC. 4. PLACES OF CIRCUIT COURT. The table in section 48(a) of title 28, United States Code, is amended-- (1) by striking the item relating to the ninth circuit and inserting the following: ``Ninth................................ San Francisco, Los Angeles.''; and (2) by inserting between the last 2 items at the end the following: ``Twelfth.............................. Portland, Seattle.''. SEC. 5. ELECTION OF ASSIGNMENT BY CIRCUIT JUDGES. (a) Except as provided in subsection (b) and notwithstanding 22 U.S.C. Sec. 44(c), each circuit judge who is in regular active service, and each judge who is a senior judge, of the former ninth circuit on the day before the effective date of this Act may elect to be assigned to the new ninth circuit or to the twelfth circuit and shall notify the Director of the Administrative Office of the United States Courts of such election. (b) Each circuit judge who is in regular active service, and each judge who is a senior judge, of the former ninth circuit and whose official station on the effective date of this Act is in Arizona may, notwithstanding 22 U.S.C. Sec. 44(c), elect to be assigned to the new ninth circuit or to the tenth circuit and shall notify the Director of the Administrative Office of the United States Courts of such election. SEC. 6. SENIORITY OF JUDGES. The seniority of each judge who elects to be assigned under section 5 of this Act shall run from the date of commission of such judge as a judge of the former ninth circuit. SEC. 7. APPLICATION TO CASES. (a) The provisions of the following paragraphs of this subsection apply to any case other than a case arising from the United States District Court for the District of Arizona in which, on the day before the effective date of this Act, an appeal or other proceeding has been filed with the former ninth circuit: (1) If the matter has been submitted for decision, further proceedings in respect of the matter shall be had in the same manner and with the same effect as if this Act had not been enacted. (2) If the matter has not been submitted for decision, the appeal or proceeding, together with the original papers, printed records, and record entries duly certified, shall, by appropriate orders, be transferred to the court to which the matter would have been submitted had this Act been in full force and effect at the time such appeal was taken or other proceeding commenced, and further proceedings in respect of the case shall be had in the same manner and with the same effect as if the appeal or other proceeding had been filed in such court. (3) A petition for rehearing or a petition for rehearing en banc in a matter decided before the effective date of this Act, or submitted before the effective date of this Act and decided on or after the effective date as provided in paragraph (1), shall be treated in the same manner and with the same effect as though this Act had not been enacted. If a petition for rehearing en banc is granted, the matter shall be reheard by a court comprised as though this Act had not been enacted. (b) Any appeal of any case pending in the United States District Court for the District of Arizona on the day before the effective date of this Act, and any further proceeding in respect of any case arising from the District Court in which an appeal or other proceeding has been filed with the former ninth circuit on such day, shall be had in the new ninth circuit. SEC. 8. DEFINITIONS. In this Act, the term-- (1) ``former ninth circuit'' means the ninth judicial circuit of the United States as in existence on the day before the effective date of this Act; (2) ``new ninth circuit'' means the ninth judicial circuit of the United States established by the amendment made by section 2(2)(A); and (3) ``twelfth circuit'' means the twelfth judicial circuit of the United States established by the amendment made by section 2(2)(C). SEC. 9. ADMINISTRATION. (a) The former ninth circuit and the tenth circuit as constituted on the day before the effective date of this Act may take such administrative actions as may be required to carry out this Act and the amendments made by this Act. (b) The former ninth circuit shall cease to exist for administrative purposes on July 1, 2005. (c) During the ten years following the date of enactment of this Act, the new ninth circuit and the twelfth circuit may meet in either circuit's jurisidiction. SEC. 10. EFFECTIVE DATE. This Act and the amendments made by this Act shall become effective on October 1, 2003.

Ninth Circuit Court of Appeals Reorganization Act of 2003 - Divides the current U.S. Court of Appeals for the ninth circuit into: (1) the ninth circuit, composed of California and Nevada, consisting of 20 judges (25 as of February 1, 2005), and holding regular sessions in San Francisco and Los Angeles; (2) the tenth circuit, composed of Arizona, Colorado, Kansas, New Mexico, Oklahoma, Utah, and Wyoming, consisting of 14 judges (as of February 1, 2005), and holding regular sessions in Denver, Wichita, and Oklahoma City; and (3) the twelfth circuit, composed of Alaska, Guam, Hawaii, Idaho, Montana, Northern Mariana Islands, Oregon, and Washington, consisting of eight judges (ten as of February 1, 2005), and holding regular sessions in Portland and Seattle.Authorizes a circuit judge of the former ninth circuit who is in regular active service or who is a senior judge to elect to be assigned to: (1) either the new ninth or twelfth circuit; or (2) the new ninth or tenth circuit if such judge's official station is in Arizona.

SECTION 1. SHORT TITLE. This Act may be cited as the ``FEGLI Living Benefits Act''. SEC. 2. OPTION TO RECEIVE ``LIVING BENEFITS''. (a) In General.--Chapter 87 of title 5, United States Code, is amended by inserting after section 8714c the following: ``Sec. 8714d. Option to receive `living benefits' ``(a) For the purpose of this section, an individual shall be considered to be `terminally ill' if such individual has a medical prognosis that such individual's life expectancy is 9 months or less. ``(b) The Office of Personnel Management shall prescribe regulations under which any individual covered by group life insurance under section 8704(a) may, if such individual is terminally ill, elect to receive a lump-sum payment equal to-- ``(1) the full amount of insurance under section 8704(a) (or portion thereof designated for this purpose under subsection (d)(4)) which would otherwise be payable under this chapter (on the establishment of a valid claim)-- ``(A) computed based on a date determined under regulations of the Office (but not later than 30 days after the date on which the individual's application for benefits under this section is approved or deemed approved under subsection (d)(3)); and ``(B) assuming continued coverage under this chapter at that time; reduced by ``(2) an amount necessary to assure that there is no increase in the actuarial value of the benefit paid (as determined under regulations of the Office). ``(c)(1) If a lump-sum payment is taken under this section-- ``(A) no insurance under the provisions of section 8704 (a) or (b) shall be payable based on the death or any loss of the individual involved, unless the lump-sum payment represents only a portion of the total benefits which could have been taken, in which case benefits under those provisions shall remain in effect, except that the basic insurance amount on which they are based-- ``(i) shall be reduced by the percentage which the designated portion comprised relative to the total benefits which could have been taken (rounding the result to the nearest multiple of $1,000 or, if midway between multiples of $1,000, to the next higher multiple of $1,000); and ``(ii) shall not be subject to further adjustment; and ``(B) deductions and withholdings under section 8707, and contributions under section 8708, shall be terminated with respect to such individual (or reduced in a manner consistent with the percentage reduction in the individual's basic insurance amount, if applicable), effective with respect to any amounts which would otherwise become due on or after the date of payment under this section. ``(2) An individual who takes a lump-sum payment under this section (whether full or partial) remains eligible for optional benefits under sections 8714a-8714c (subject to payment of the full cost of those benefits in accordance with applicable provisions of the section or sections involved, to the same extent as if no election under this section had been made). ``(d)(1) The Office's regulations shall include provisions regarding the form and manner in which an application under this section shall be made and the procedures in accordance with which any such application shall be considered. ``(2) An application shall not be considered to be complete unless it includes such information and supporting evidence as the regulations require, including certification by an appropriate medical authority as to the nature of the individual's illness and that the individual is not expected to live more than 9 months because of that illness. ``(3)(A) In order to ascertain the reliability of any medical opinion or finding submitted as part of an application under this section, the covered individual may be required to submit to a medical examination under the direction of the agency or entity considering the application. The individual shall not be liable for the costs associated with any examination required under this subparagraph. ``(B) Any decision by the reviewing agency or entity with respect to an application for benefits under this section (including one relating to an individual's medical prognosis) shall not be subject to administrative review. ``(4)(A) An individual making an election under this section may designate that only a limited portion (expressed as a multiple of $1,000) of the total amount otherwise allowable under this section be paid pursuant to such election. ``(B) A designation under this paragraph may not be made by an individual described in paragraph (1) or (2) of section 8706(b). ``(5) An election to receive benefits under this section shall be irrevocable, and not more than one such election may be made by any individual. ``(6) The regulations shall include provisions to address the question of how to apply section 8706(b)(3)(B) in the case of an electing individual who has attained 65 years of age.''. (b) Table of Sections.--The table of sections for chapter 87 of title 5, United States Code, is amended by inserting after the item relating to section 8714c the following: ``8714d. Option to receive `living benefits'.''. SEC. 3. EFFECTIVE DATE; OPEN SEASON AND NOTICE. (a) Effective Date.--The amendments made by section 2 shall take effect 9 months after the date of the enactment of this Act. (b) Open Season; Notice.--(1) The Office of Personnel Management shall prescribe regulations under which, beginning not later than 9 months after the date of the enactment of this Act, and over a period of not less than 8 weeks-- (A) an employee (as defined by section 8701(a) of title 5, United States Code) who declined or voluntarily terminated coverage under chapter 87 of such title-- (i) may elect to begin, or to resume, group life insurance and group accidental death and dismemberment insurance; and (ii) may make such other elections under such chapter as the Office may allow; and (B) such other elections as the Office allows may be made. (2) The Office shall take such action as may be necessary to ensure that employees and any other individuals who would be eligible to make an election under this subsection are afforded advance notification to that effect. SEC. 4. FUNDING. Notwithstanding section 8714(a)(1) of title 5, United States Code, the Office of Personnel Management shall retain in the Employees' Life Insurance Fund such portion of premium payments otherwise due as will, no later than September 30, 1995, permanently reduce the contingency reserve established under the third sentence of section 8712 of such title 5 by an amount equal to the amount by which payments from the Employees' Life Insurance Fund during the fiscal year ending September 30, 1995, exceed the payments that would have been paid had the amendments made by this Act not been enacted. SEC. 5. CONTINUATION OF HEALTH BENEFITS COVERAGE FOR INDIVIDUALS ENROLLED IN A PLAN ADMINISTERED BY THE OFFICE OF THE COMPTROLLER OF THE CURRENCY OR THE OFFICE OF THRIFT SUPERVISION. (a) Enrollment in Chapter 89 Plan.--For purposes of the administration of chapter 89 of title 5, United States Code, any period of enrollment under a health benefits plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision before the termination of such plans on January 7, 1995, shall be deemed to be a period of enrollment in a health benefits plan under chapter 89 of such title. (b) Continued Coverage.--(1) Any individual who, on January 7, 1995, is covered by a health benefits plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision may enroll in an approved health benefits plan described under section 8903 or 8903a of title 5, United States Code-- (A) either as an individual or for self and family, if such individual is an employee, annuitant, or former spouse as defined under section 8901 of such title; and (B) for coverage effective on and after January 8, 1995. (2) An individual who, on January 7, 1995, is entitled to continued coverage under a health benefits plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision-- (A) shall be deemed to be entitled to continued coverage under section 8905a of title 5, United States Code, for the same period that would have been permitted under the plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision; and (B) may enroll in an approved health benefits plan described under section 8903 or 8903a of such title in accordance with section 8905a of such title for coverage effective on and after January 8, 1995. (3) An individual who, on January 7, 1995, is covered as an unmarried dependent child under a health benefits plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision and who is not a member of family as defined under section 8901(5) of title 5, United States Code-- (A) shall be deemed to be entitled to continued coverage under section 8905a of such title as though the individual had, on January 7, 1995, ceased to meet the requirements for being considered an unmarried dependent child under chapter 89 of such title; and (B) may enroll in an approved health benefits plan described under section 8903 or 8903a of such title in accordance with section 8905a for continued coverage effective on and after January 8, 1995. (c) Transfers to the Employees Health Benefits Fund.--The Office of the Comptroller of the Currency and the Office of Thrift Supervision shall transfer to the Employees Health Benefits Fund established under section 8909 of title 5, United States Code, amounts determined by the Director of the Office of Personnel Management, after consultation with the Office of the Comptroller of the Currency and the Office of Thrift Supervision, to be necessary to reimburse the Fund for the cost of providing benefits under this section not otherwise paid for by the individuals covered by this section. The amounts so transferred shall be held in the Fund and used by the Office in addition to amounts available under section 8906(g)(1) of such title. (d) Administration and Regulations.--The Office of Personnel Management-- (1) shall administer the provisions of this section to provide for-- (A) a period of notice and open enrollment for individuals affected by this section; and (B) no lapse of health coverage for individuals who enroll in a health benefits plan under chapter 89 of title 5, United States Code, in accordance with this section; and (2) may prescribe regulations to implement this section. Speaker of the House of Representatives. Vice President of the United States and President of the Senate.

FEGLI Living Benefits Act - Provides that a Federal employee enrolled in the Federal Employees Group Life Insurance (FEGLI) Program who has been diagnosed as terminally ill with a life expectancy of nine months or less may elect to receive a lump-sum payment of his or her basic insurance amount, as adjusted actuarially under regulations of the Office of Personnel Management (OPM). Requires OPM to retain in the Employees Life Insurance Fund the portion of premium payments otherwise due as will, by the end of FY 1995, permanently reduce the contingency reserve by an amount equal to the amount by which payments from the Fund during FY 1995 exceed the payments that would have been paid had this Act not been enacted. Provides for continuation of health benefits coverage for individuals enrolled in a plan administered by the Office of the Comptroller of the Currency or the Office of Thrift Supervision before the plan's termination on January 7, 1995. Requires transfer of terminated plan funds to the Employees Health Benefit Fund to cover such employees.

the recurrent laryngeal nerve ( rln ) injury is one of the most important complications during thyroid surgery , leading to dysfunction , and palsy of the vocal cords . for years , surgeons have attempted to prevent this complication by improving surgical techniques and optimizing surgical strategies . the identification and preservation of the anatomical integrity of the rln during thyroid surgery is commonly accepted as a gold standard . however , even in the most experienced hands , rln injury occasionally occurs . in the last decade , intraoperative neuromonitoring ( ionm ) has been widely applied during thyroid surgery to aid in the localization and identification of the rln . one of the most important roles of ionm is assistance in intraoperative navigation and rapid identification of rln distribution . repetitive tissue stimulation in the vicinity of the nerve allows the nerve to be localized using a stimulation probe before visual identification . the reported stimulation intensity for mapping the path of the nerve ranges from 2 to 3 ma . this range is higher than that used for direct nerve stimulation , as the use of stronger stimulation current would depolarize a greater sphere of tissue around the probe tip however , failure to obtain signal deflection at 3 ma during nerve localization might occasionally occur , in which case a surgeon might consider increasing the stimulation intensity . however , electrical stimulation is also a potential risk factor for rln injury , and the nerve can become damaged in the case of over - stimulation . therefore , in this study , we developed an experimental canine model to determine whether supramaximal stimulation during ionm could induce nerve damage and investigated the safe range of stimulation current intensity . twenty adult , male beagle dogs weighing 1520 kg were obtained from the animal center of peking university health science center ( institutional protocol no . the dogs were randomly divided into four groups of five each and maintained under standard laboratory conditions with free access to food and water . all animal experiments were approved by the institutional ethics committee ( peking university people 's hospital ) , and all procedures were conducted according to our institutional animal care guidelines . the animals were fasted for 8 h and then anesthetized with intravenous 3% pentobarbital ( merck kgaa , darmstadt , germany ) 5 ml and vecuronium ( organon pharmaceutical co. , ltd . , oss , the netherlands ) 0.06 mg / kg , after which a neural monitoring tube ( medtronic nim 2 emg ett # 6 ; medtronic , jacksonville , florida , usa ) was inserted by a single anesthesiologist . , new york , usa ) to ensure that the middle of its blue - marked region ( the exposed electrodes ) formed a good contact with the true vocal cords . the tube was then fixed by balloon inflation . after performing routine surgical procedures such as disinfection and draping , a midline vertical cervical incision was made to expose the neck and the larynx , and total thyroidectomy was performed . a nerve integrity monitor ( nim - response 2.0 ; medtronic , jacksonville , florida , usa ) was applied for ionm approximately 20 min after the administration of muscle relaxant , at the moment of muscle recovery . the following parameters were set : stimulation rate , four times / s ; pulse width , 100 s ; and event threshold , 100 s . while exposing the bilateral rln , a stimulation current was delivered to the nerves by a bipolar probe at a 30 hz frequency . the electrode detected evoked electromyography ( emg ) activity , the parameters of which were recorded . after finishing the experimental procedures , the incisions were closed in multiple layers , and the animals were sacrificed by an intravenous bolus injection of potassium chloride . all surgeries were performed by the same surgeon , who is experienced in thyroid surgery . the stimulation threshold was defined as the lowest current required to obtain clear evoked emg . each nerve was initially stimulated using a 0.1 ma current , and the current was increased step - wise by 0.05 ma until emg was observed . the current was recorded as the stimulation threshold , and the corresponding amplitude was recorded as well . after exposure of the rln , the stimulation threshold and amplitude at the threshold level were measured as baseline parameters before any interventions . then , the rlns were continuously stimulated with a high - intensity current for 1 min at a point distal from the test point . each group of animals was exposed to a different stimulation intensity ( 5 ma , 10 ma , 15 ma , and 20 ma ) . the stimulation threshold and evoked emg amplitude were measured 1 min later at the same point as the prior test to determine poststimulation parameters . all interventions and recordings were performed completely on one side before treating the other side . the specimens were prepared using the following steps : ( 1 ) immediate fixing in 3% glutaraldehyde ( sigma - aldrich co. llc . , st . louis , usa ) ; ( 2 ) three washes of 20 min each with phosphate - buffered solution ( zoman bio co. , ltd . , beijing , china ) ; ( 3 ) fixing in osmic acid ( alfa aesar , massachusetts , usa ) for 1.52.0 h ; ( 4 ) two washes with distilled water ( sinopharm chemical reagent beijing co. , ltd , beijing , china ) ; ( 5 ) immersion in uranium ( merck kgaa , darmstadt , germany ) for 30 min ; ( 6 ) two washes with distilled water ; ( 7 ) dehydration with graded ethanol ( beijing chemical works , beijing , china ) ( 50% , 70% , 90% , and 100% for 15 min each ) ; ( 8) embedding in 1:1 100% acetone ( beijing chemical works , beijing , china ) under vacuum for 23 h ; ( 9 ) embedding in 1:3 100% acetone : under vacuum for 23 h ; ( 10 ) embedding and immersion at 37c for 1620 h ; ( 11 ) polymerization at 60c for 48 h ; and ( 12 ) drying for 24 h. finally , the myelin sheath , neuraxon , and schwann cell nerve microstructures were observed under an electron microscope ( jeol ltd . , data were analyzed using spss 17.0 statistical software ( spss inc . , chicago , il , usa ) . paired t - tests were used to compare the average stimulation thresholds and amplitudes at the threshold level between normal and stimulated rlns . twenty adult , male beagle dogs weighing 1520 kg were obtained from the animal center of peking university health science center ( institutional protocol no . the dogs were randomly divided into four groups of five each and maintained under standard laboratory conditions with free access to food and water . all animal experiments were approved by the institutional ethics committee ( peking university people 's hospital ) , and all procedures were conducted according to our institutional animal care guidelines . the animals were fasted for 8 h and then anesthetized with intravenous 3% pentobarbital ( merck kgaa , darmstadt , germany ) 5 ml and vecuronium ( organon pharmaceutical co. , ltd . , oss , the netherlands ) 0.06 mg / kg , after which a neural monitoring tube ( medtronic nim 2 emg ett # 6 ; medtronic , jacksonville , florida , usa ) was inserted by a single anesthesiologist . , new york , usa ) to ensure that the middle of its blue - marked region ( the exposed electrodes ) formed a good contact with the true vocal cords . after performing routine surgical procedures such as disinfection and draping , a midline vertical cervical incision was made to expose the neck and the larynx , and total thyroidectomy was performed . a nerve integrity monitor ( nim - response 2.0 ; medtronic , jacksonville , florida , usa ) was applied for ionm approximately 20 min after the administration of muscle relaxant , at the moment of muscle recovery . the following parameters were set : stimulation rate , four times / s ; pulse width , 100 s ; and event threshold , 100 s . while exposing the bilateral rln , a stimulation current was delivered to the nerves by a bipolar probe at a 30 hz frequency . the electrode detected evoked electromyography ( emg ) activity , the parameters of which were recorded . after finishing the experimental procedures , the incisions were closed in multiple layers , and the animals were sacrificed by an intravenous bolus injection of potassium chloride . all surgeries were performed by the same surgeon , who is experienced in thyroid surgery . the stimulation threshold was defined as the lowest current required to obtain clear evoked emg . each nerve was initially stimulated using a 0.1 ma current , and the current was increased step - wise by 0.05 ma until emg was observed . the current was recorded as the stimulation threshold , and the corresponding amplitude was recorded as well . after exposure of the rln , the stimulation threshold and amplitude at the threshold level were measured as baseline parameters before any interventions . then , the rlns were continuously stimulated with a high - intensity current for 1 min at a point distal from the test point . each group of animals was exposed to a different stimulation intensity ( 5 ma , 10 ma , 15 ma , and 20 ma ) . the stimulation threshold and evoked emg amplitude were measured 1 min later at the same point as the prior test to determine poststimulation parameters . all interventions and recordings were performed completely on one side before treating the other side . the specimens were prepared using the following steps : ( 1 ) immediate fixing in 3% glutaraldehyde ( sigma - aldrich co. llc . , st . louis , usa ) ; ( 2 ) three washes of 20 min each with phosphate - buffered solution ( zoman bio co. , ltd . , beijing , china ) ; ( 3 ) fixing in osmic acid ( alfa aesar , massachusetts , usa ) for 1.52.0 h ; ( 4 ) two washes with distilled water ( sinopharm chemical reagent beijing co. , ltd , beijing , china ) ; ( 5 ) immersion in uranium ( merck kgaa , darmstadt , germany ) for 30 min ; ( 6 ) two washes with distilled water ; ( 7 ) dehydration with graded ethanol ( beijing chemical works , beijing , china ) ( 50% , 70% , 90% , and 100% for 15 min each ) ; ( 8) embedding in 1:1 100% acetone ( beijing chemical works , beijing , china ) under vacuum for 23 h ; ( 9 ) embedding in 1:3 100% acetone : under vacuum for 23 h ; ( 10 ) embedding and immersion at 37c for 1620 h ; ( 11 ) polymerization at 60c for 48 h ; and ( 12 ) drying for 24 h. finally , the myelin sheath , neuraxon , and schwann cell nerve microstructures were observed under an electron microscope ( jeol ltd . , tokyo , japan ) . data were analyzed using spss 17.0 statistical software ( spss inc . , chicago , il , usa ) . paired t - tests were used to compare the average stimulation thresholds and amplitudes at the threshold level between normal and stimulated rlns . a value of p < 0.05 was considered statistically significant . the bilateral rlns of all 20 dogs were successfully exposed ; therefore , 10 nerves per group were available for experimentation . the average stimulation thresholds of the unstimulated rlns in the 15 ma group and 20 ma group were 0.315 0.097 ma and 0.300 0.103 ma , and the average amplitudes at the threshold level were 1,021 273 v and 1,200 258 v , respectively . the data from the groups stimulated with 5 ma and 10 ma were accidentally lost . after the experimental invention , no significant difference in average stimulation threshold was observed in any group [ 15 ma group : unstimulated 0.315 0.097 ma vs. stimulated 0.320 0.123 ma , p = 0.847 ; 20 ma group : unstimulated 0.300 0.103 ma vs. stimulated 0.305 0.101 ma , p = 0.758 ; table 1 ] . similarly , there was no statistically significant change in average evoked emg amplitude in any group , even the group stimulated with 20 ma [ 15 ma group : unstimulated 1,021 273 v vs. stimulated 1,026 268 v , p = 0.834 ; 20 ma group : unstimulated 1,200 258 v vs. stimulated 1,162 275 v , p = 0.148 ; table 2 ] . stimulation threshold changes for recurrent laryngeal nerves after electrical stimulation at different intensities sd : standard deviation . changes in evoked electromyography amplitude of the recurrent laryngeal nerve after electrical stimulation at different intensities sd : standard deviation . no significant pathological changes were observed among the specimens from the 5 ma , 10 ma , and 15 ma groups compared to the normal group under electron microscopy [ figure 1 ] . aligned microfilaments , evenly distributed matrix , and normal organelles were clearly observed without schwann cell degeneration or proliferation [ figure 2 ] . electron microscopic image of a normal recurrent laryngeal nerve ( original magnification , 10,000 ) . electron microscopic image of a recurrent laryngeal nerve continuously stimulated with a 15 ma current for 1 min ( original magnification 10,000 ) . electron microscopic image of a recurrent laryngeal nerve stimulated with a 20 ma current for 1 min . the bilateral rlns of all 20 dogs were successfully exposed ; therefore , 10 nerves per group were available for experimentation . the average stimulation thresholds of the unstimulated rlns in the 15 ma group and 20 ma group were 0.315 0.097 ma and 0.300 0.103 ma , and the average amplitudes at the threshold level were 1,021 273 v and 1,200 258 v , respectively . the data from the groups stimulated with 5 ma and 10 ma were accidentally lost . after the experimental invention , no significant difference in average stimulation threshold was observed in any group [ 15 ma group : unstimulated 0.315 0.097 ma vs. stimulated 0.320 0.123 ma , p = 0.847 ; 20 ma group : unstimulated 0.300 0.103 ma vs. stimulated 0.305 0.101 ma , p = 0.758 ; table 1 ] . similarly , there was no statistically significant change in average evoked emg amplitude in any group , even the group stimulated with 20 ma [ 15 ma group : unstimulated 1,021 273 v vs. stimulated 1,026 268 v , p = 0.834 ; 20 ma group : unstimulated 1,200 258 v vs. stimulated 1,162 275 v , p = 0.148 ; table 2 ] . stimulation threshold changes for recurrent laryngeal nerves after electrical stimulation at different intensities sd : standard deviation . changes in evoked electromyography amplitude of the recurrent laryngeal nerve after electrical stimulation at different intensities sd : standard deviation . no significant pathological changes were observed among the specimens from the 5 ma , 10 ma , and 15 ma groups compared to the normal group under electron microscopy [ figure 1 ] . aligned microfilaments , evenly distributed matrix , and normal organelles were clearly observed without schwann cell degeneration or proliferation [ figure 2 ] . electron microscopic image of a normal recurrent laryngeal nerve ( original magnification , 10,000 ) . electron microscopic image of a recurrent laryngeal nerve continuously stimulated with a 15 ma current for 1 min ( original magnification 10,000 ) . electron microscopic image of a recurrent laryngeal nerve stimulated with a 20 ma current for 1 min . rln injury is a major complication of thyroid surgery . such injury results in temporary or permanent recurrent laryngeal nerve palsy ( rlnp ) , which manifests as hoarseness in unilateral injury or life - threatening acute airway obstruction in bilateral injury . temporary rlnp occurs in 1.438.4% of cases while permanent palsy occurs in 018.6% of cases . the strategy used for thyroid surgery has advanced to routine capsular dissection and direct visualization of the rln , which is accepted as the gold standard due to its association with a significantly lower rlnp rate . ionm was recently introduced to aid in the localization and identification of the rln and as a prognostic measure of postoperative nerve function . early and definite identification of the rln during thyroid surgery , especially in difficult cases , is important for preventing rln injury . previously reported stimulus intensities used to localize the nerve before visualization has ranged from 1 to 3 ma . many studies have confirmed that the stimulation current that is routinely used is safe and meets the demands required for surgery most of the time . however , it has been clearly demonstrated that over - stimulation induces tissue damage , which may result from the passage of current through the tissue . the range of stimulation current intensity that can be safely applied during clinical practice remains to be determined . in this study , we used twenty dogs to evaluate the functional and histological outcomes of applying supramaximal electrical stimulation to the rln . the safety of stimulation with 3 ma has been widely confirmed in clinical and animal experiments . in a study reported by ulmer et al . , the maximal current used for stimulation was 5 ma , and no postoperative rlnp was detected . however , stimulation with 5 ma during ionm has rarely been used in the clinic . in the current study , we initially treated animals with a current of 5 ma and observed no functional and histological changes after the intervention , verifying its safety . previous studies in canine or porcine models that have characterized emg changes , such as amplitude decrements and increases in stimulation threshold level after neural injury , have suggested that these parameters can be used as predictors of nerve injury . even after stimulation with 20 ma , there was still no functional abnormality in the nerve based on the stimulation thresholds and evoked emg amplitudes observed . normal morphology was observed after stimulation with 15 ma , but acute microstructural morphological changes occurred after stimulation with 20 ma . the anatomical and functional correlations of our canine model might be translatable into a safe range of stimulation intensity for ionm during human thyroid surgery . despite losing the data from the groups stimulated with 5 ma and 10 ma , based on our results , we postulate that a stimulation intensity less than 15 ma will not induce any functional or histological changes to rlns during ionm . we chose to evaluate a canine model because dog thyroid glands have similar anatomy to human thyroid glands and therefore can be used to mimic human thyroid surgery . the canine thyroid is a dark red , elongated structure that is attached to the fascia along the ventrolateral surfaces of the proximal trachea , ventrally covered by the sternocephalicus and sternohyoideus muscles , and laterally covered by the sternothyroideus muscle . the caudal laryngeal nerves in dogs , termed rlns in humans , are dorsal to the thyroid lobes . one limitation of the current study is the loss of the data from the groups stimulated with the low - intensity current . another limitation was the lack of exclusion of influencing factors and the absence of functional evaluation of the nerves , such as the observation of vocal cord movement by video laryngoscopy . however , this study provides evidence for the safety of using electrical stimulation during ionm in clinical practice . in conclusion , our study indicates that a stimulation intensity less than 15 ma could be safely applied during ionm .

background : intraoperative neuromonitoring ( ionm ) of the recurrent laryngeal nerve ( rln ) has been widely applied during thyroid surgery . however , the safe range of stimulation intensity for ionm remains undetermined.methods:total thyroidectomies were performed on twenty dogs , and their rlns were stimulated with a current of 520 ma ( step - wise in 5 ma increments ) for 1 min . the evoked electromyography ( emg ) of vocal muscles before and after supramaximal stimulation were recorded and compared . acute microstructural morphological changes in the rlns were observed immediately postoperatively under an electron microscope.results:the average stimulating threshold for rlns stimulated with 15 ma and 20 ma showed no significant changes compared to the unstimulated rlns ( 15 ma group : 0.320 0.123 ma vs. 0.315 0.097 ma , p = 0.847 ; 20 ma group : 0.305 0.101 ma vs. 0.300 0.103 ma , p = 0.758 ) . similar outcomes were shown in average evoked emg amplitude ( 15 ma group : 1,026 268 v vs. 1,021 273 v , p = 0.834 ; 20 ma group : 1,162 275 v vs. 1,200 258 v , p = 0.148 ) . however , obvious acute microstructural morphological changes were observed in the nerves that were stimulated with 20 ma.conclusions:a stimulation intensity less than 15 ma might be safe for ionm of the rln .

cancer is a major public health concern in the united states with approximately 25% of total deaths attributed to cancer . the projected number of cancer deaths in 2010 alone was 1500 deaths per day , corresponding to a total of over 560,000 deaths . therefore , investigations into modifiable risk factors that may reduce the rates of cancer mortality continue to be of significant importance . physical activity has been hypothesized to protect against cancer through obesity reduction , improved insulin sensitivity and sex hormone profiles , and lowered inflammation . the world cancer research fund / american institute for cancer research expert panel report concluded that physical activity likely reduces the risk of some cancers and suggested an active lifestyle for protection against cancer progression and mortality . however , concrete recommendations for physical activity to prevent cancer mortality are lacking , in part , due to inconsistencies in the existing evidence , and due to varying methodology and differing definitions of physical activity used . furthermore , at this time associations with physical activity are better established for cancer incidence as compared to mortality [ 4 , 5 ] . a greater understanding of the protective effects of physical activity may enhance existing cancer control strategies and potentially reduce cancer mortality . the present study strengthens the evidence in the current literature by examining longitudinal associations between leisure - time physical activity ( ltpa ) in the third national health and nutrition examination survey ( nhanes iii : 19881994 ) linked to mortality data through 2006 . excess adiposity and aberrations in the insulin - glucose axis are hypothesized to promote carcinogenesis [ 6 , 7 ] and may offset the protective potential of physical activity . it is noteworthy that research in the area of cancer mortality has typically focused on a single risk factor . less attention has been devoted to the combined effects of body weight , insulin resistance ( ir ) , physical activity , and cancer mortality [ 811 ] , and the interrelationships of these risk factors warrant investigation . therefore the current study is designed to expand the physical activity - cancer hypothesis by assessing whether body mass index ( bmi ) and ir modify the relationships of physical activity and cancer mortality . existing data available from this national sample on body weight , laboratory values , self - reported physical activity data , and cancer mortality ( n = 863 ) provides a unique opportunity to conduct these analyses . the results of this study provide data to guide clinical trials that may ultimately contribute to individualized physical activity recommendations for cancer control . the nhanes iii ( 19881994 ) population , a national sample of civilian noninstitutionalized individuals , was selected through a complex , multistage probability design . persons who were 17 + or older were eligible for the mortality follow - up from the date of participation ( 19881994 ) through december 31 , 2006 . this represents the last nhanes iii mortality update . the current analyses included adults 2089 years . per the adult treatment panel ( atp ) definition , individuals were considered to be adults if they were at least 20 years old . nhanes participants 89 + years were assigned an arbitrary age of 90 years for confidentiality purposes and were excluded from the analyses . pregnant women were excluded because their baseline physical activity and bmi may not be an accurate reflection of their usual activity or body weight . additionally , persons with missing values for the pertinent variables were also excluded , resulting in a final sample of 15,535 individuals . the nhanes iii survey consisted of a structured household interview and a standardized physical examination in a mobile examination center at entry into the study . participants self - reported their age , race / ethnicity , level of education , leisure - time physical activity , dietary intakes , alcohol use , current prescription medication , and presence of doctor - diagnosed cancer in a personal interview . race / ethnicity were categorized into ( 1 ) non - hispanic whites , ( 2 ) non - hispanic blacks , ( 3 ) mexican - americans and ( 4 ) other . trained personnel measured height , weight and waist circumference during the in - person examination . the measured height and weight were used to compute bmi . smoking status was assessed during the in - person interview , in which participants reported the use of cigarettes , pipes , and cigars . a fasting blood sample was obtained during the physical examination that was used to measure fasting plasma glucose concentrations . a questionnaire consisting leisure - time physical activity questions including type of activity and frequency of the activity in the past month was queried in the household adult questionnaire administered once at baseline . there was no additional follow - up information on physical activity and other variables after time of entry into the study until the end of mortality follow - up ( figure 1 ) . at baseline , participants were asked for example , if in the past month , did you run or jog ? and in the past month , how often did you jog or run ? similarly , questions were asked on walking , bicycling , swimming , aerobics and/or aerobic dancing , other dancing , calisthenics , yard work , lifting weights , and engagement in up to four other activities that were not mentioned in the survey . frequency of engagement in activities over the past 30 days was reported . these responses were standardized to weekly frequency by using the conversion factors of 4.3 weeks / month and 30.4 days / month per nhanes iii . a validated intensity rating in metabolic equivalents ( met ) was provided by nhanes iii for each activity as defined in the compendium of physical activities . for example , jogging / running was assigned an intensity rating of 8 mets . for this study , low intensity , moderate and vigorous using the standard cut - offs established by pate et al . . low - intensity , activities requiring 36 mets were classified as moderate and > 6 mets were classified as vigorous . participants who did not report engagement in any of the activities , were classified as because individuals engaging in low intensity activities represented < 0.05% ( n = 7 ) of the population , they were combined into the moderate exercises if they reported performing the activity at least 5 times per week and regular vigorous if they reported performing vigorous activities at least 3 times per week . these categories were mutually exclusive ( so that if an individual performed vigorous and low - to - moderate activities , he / she was included in the vigorous activity group and not in both groups ) . additionally , a frequency - weighted ltpa variable was calculated by multiplying the frequency of each activity by its corresponding intensity value and summed . the nhanes iii survey did not collect information for duration of each bout of exercise , which limits more precise estimation of physical activity . the physical activity definitions used in this study are consistent with previously published studies using the nhanes iii population [ 1821 ] . mortality information was obtained from the updated nhanes iii linked mortality files that provide mortality follow - up data from the date of participation in the survey ( 19881994 ) through december 31 , 2006 ( figure 1 ) . mortality was ascertained based upon either death certificates or from a probabilistic match between nhanes iii and the national center for health statistics , national death index ( ndi ) records . cancer mortality was identified using the international classification of diseases , tenth revision ( icd-10 ; nchs 2006 ; icd-10 codes c00c97 ) . persons were considered alive at the end of the follow - up period if they were not matched to a death record . descriptive statistics were generated to assess demographic , lifestyle and dietary attributes related with cancer mortality , and to identify potential confounders . next , unadjusted univariate hazard ratio ( hr ) and 95% confidence intervals ( 95% ci ) of overall cancer mortality and level of ltpa were computed using cox proportional hazard models , using age as the time scale . persons who died from causes other than cancer were censored at the age of death and persons who were considered alive were censored at the end of the study follow - up period . we tested demographic , lifestyle , physiological , and dietary factors as potential confounders of the associations of ltpa and cancer mortality , by entering these additional variables singly into the cox proportional hazards models . if the addition of the variable singly in the model changed the hr for cancer mortality by 10% or more , the variable was added to the final regression model . potential variables tested were age ( continuous and years ) , race or ethnicity ( categorical : white , black , mexican , and other ) , cardiovascular disease ( categorical : yes / no ) , bmi ( categorical : normal weight , overweight and obese ) , smoking ( categorical : never , current , past ) , alcohol consumption ( continuous : number of drinks / day ) , education ( categorical : < 12 and 12 years ) , aspirin use ( yes / no ) total dietary proteins ( continuous : grams / day ) , total dietary fats ( continuous : grams / day ) total dietary carbohydrates ( continuous : grams / day ) , and total calories ( continuous : kilocalories / day ) . we tested for potential effect modification ( considered significant for the purpose of these analyses at alpha value of 0.10 or less ) by race , age , gender , bmi , and ir status for the relationships of physical activity and cancer mortality . a significance level of 0.05 sensitivity analyses were conducted by reanalyzing the associations after excluding persons with a baseline report of doctor - diagnosed cancer ( n = 588 ) . for exploratory purposes , we repeated analyses in adults 40 + years at baseline ( n = 9348 ) . the statistical analyses were performed using sas v.9.1 and sudaan v.10.0.1 sample weights provided by nhanes iii were applied to all the analyses . baseline characteristics of nhanes iii sample are expressed as either weighted frequencies for categorical variables or weighted means with their corresponding standard errors ( ses ) , and minimum and maximum values for continuous variables ( table 1 ) . the population consisted of 76.8% non - hispanic whites , 10.4% non - hispanic blacks , 5.2% mexican - americans , and 7.8% other ethnicities . approximately 85% of the participants reported engaging in any physical activity , with half ( 53.3% ) of the population being moderately and 16.9% being vigorously active on a regular basis . about 15% of the sample was inactive . furthermore , 33% of the participants reported being more active , 21% reported being less active , and 44% estimated about the same level of activity as compared to their peers of the same sex and similar age . over half the population was obese or overweight ( bmi > 25 ) , with a mean waist circumference of 92 cm . twenty - two percent of the population had the insulin resistance syndrome , defined per the atp iii criteria as having at least three of the following five criteria : abdominal obesity ( waist circumference > 102 cm in men or > 88 cm in women ) , insulin resistance ( blood glucose > 110 mg / dl ) , low high density lipoprotein ( hdl ) ( < 40 in men or < 50 in women ) , high serum triglycerides concentration ( > 150 mg / dl ) , and hypertension ( systolic blood pressure > 130 mm hg or diastolic blood pressure > 85 mm hg . ) and 10.67% were insulin resistant ( defined as blood glucose levels > 110 mg / dl ) . in this dataset 5.5% ( n = 863 ) of the population had died from cancer at the end of the follow - up period till 2006 . approximately 15% of the patients who had died of cancer had reported doctor - diagnosed cancer during their in - person baseline interview . overall , nonsignificant inverse associations were observed for overall cancer mortality among persons engaging in any activity , regular low - to - moderate or regular vigorous activity in the whole population ( table 2 ) . individuals who engaged in any activity were 8% and 5% less likely to die of cancer as compared to individuals who were inactive , after adjusting for age ( hr : 0.92 ; 95% ci : 0.711.19 ) and additional variables ( hr : 0.95 ; 95% ci : 0.721.26 ) , respectively . associations were in a similar direction for regular low - to - moderate activity ( hr : 0.92 ; 95% ci : 0.691.21 ) , regular vigorous activity ( hr : 0.66 ; 95% ci : 0.391.13 ) , and for the highest versus lowest quartile of frequency - weighted mets per week ( hr : 0.89 ; 95% ci : 0.681.16 ) after adjusting for age , race , sex , and smoking status , albeit not statistically significant . analyses were repeated after excluding self - reported history of cancer at baseline ( n = 588 ) to assess whether the observed nonsignificant associations persisted . the hrs among individuals with no history of cancer at baseline ranged from 0.82 to 1.09 for all levels of regular ltpa ; however , the hrs were not statistically significant after adjusting for age and additional covariates in the whole population and the conclusions remained unchanged ( table 2 ) . restricting analyses to adults 40 + years at baseline yielded similar results ( data not shown ) . previous research has reported that bmi and ir are associated with cancer mortality [ 6 , 23 , 24 ] . significant effect modification ( a priori considered significant if p < 0.1 ) by ir in the relationships of physical activity and overall cancer mortality were noted ( p = 0.07 ) . therefore , the analyses were stratified by ir status ( yes / no ) as shown in table 3 . among individuals who were not insulin resistant , significant 54% ( hr : 0.46 ; 95% ci : 0.240.87 ) and 49% ( hr : 0.51 ; 95% ci : 0.270.97 ) decreased risk were observed between engagement in regular vigorous activity and overall cancer mortality , after adjusting for age and additional variables , respectively . among individuals who were insulin resistant , an 82% increased risk of cancer mortality was observed ( hr : 1.82 ; 95% ci : 0.714.65 ) , albeit this finding was not statistically significant and therefore can not be considered definitive . these associations persisted when the relationships were reevaluated in a sample after excluding persons with a cancer diagnosis at baseline , in sensitivity analyses ( data not shown ) . although there was no significant effect modification by bmi ( p = 0.355 ) , for exploratory purposes only , the analyses were stratified by bmi < 25 ( normal weight ) and > 25 ( obese or overweight ) . among persons with a lower bmi , the observed inverse associations were more protective for any activity and overall cancer mortality , albeit non - significant after adjusting for age ( hr : 0.82 ; 95% ci : 0.551.22 ) and additional variables ( hr : 0.90 ; 95% ci : 0.611.35 ) as compared to individuals with a bmi > 25 ( ( age - adjusted hr : 1.02 ; 95% ci : 0.731.42 ) and ( adjusted for additional variables hr : 1.03 ; 95% ci : 0.731.46 ) ) . the hr were similarly < 1 but remained non - significant among persons with a normal bmi engaging in regular low - to - moderate or regular vigorous ltpa . the direction of the associations persisted when reevaluated after excluding persons with no cancer diagnosis at baseline ( data not shown ) . next , the frequency - weighted mets / week variable was divided into quartiles in the cox proportional regression models . quartile 1 was the referent group and represented participants with the lowest level of mets expended , and quartile 4 represented the individuals with the highest level of mets expended . although not significant , the hrs for quartiles 2 , 3 , and 4 were < 1 as compared to quartile 1 . the non - significant decreased risk for cancer mortality persisted after excluding persons with a cancer diagnosis at baseline ( data not shown ) . furthermore , hrs were similar when analyses were repeated among individuals who were 40 years or older at baseline . the current study was undertaken to elucidate the relationships between ltpa and cancer mortality in a nationally representative dataset and its linkage to mortality status ( 19882006 ) . the comprehensive data available in the nhanes iii sample on obesity , insulin resistance , and physical activity history provided a unique opportunity to evaluate the combined impact of these factors on longitudinally ascertained cancer mortality , an approach that has typically not been used in the previous studies . although the results of the current study are not statistically significant in the whole population , they are suggestive of protection against overall cancer mortality , specifically for vigorous activity ( hr < 1 ) . this study is similar to previous studies that have evaluated physical activity in relation to overall cancer mortality of site - specific cancer mortality . for example , a recent prospective cohort study among elder japanese adults noted that high levels of physical activity ( 5 or more days per week ) were associated with a 23% decreased risk of overall cancer mortality ( p for trend = 0.02 ) . previous studies have shown that physical activity protects against mortality from some common cancers including lung , prostate [ 10 , 26 ] , breast [ 2729 ] , and colon cancer . we observed a slight attenuation of the non - significant associations in the sensitivity analyses after excluding persons with self - reported cancer at baseline . this could perhaps be due to lifestyle changes among the cancer cases after diagnosis , or due to reverse causality . however , unavailability of follow - up measures of physical activity in the nhanes iii survey limits the complete understanding of this phenomenon . furthermore , the current study suggests that the protection afforded by ltpa may be realized in the absence of aberrations in the insulin - glucose axis . we note that the protective associations of ltpa and cancer mortality were more pronounced among non - insulin - resistant individuals who engaged in vigorous ltpa . several biological mechanisms may explain the potential protective role of physical activity against cancer mortality . insulin , an anabolic hormone , is hypothesized to promote cell proliferation , inhibit apoptosis , and support cancer progression [ 3032 ] . studies have demonstrated that the benefits of physical activity are apparent even in the absence of changes in body weight [ 2 , 35 ] . ir is associated with increased levels of sex hormones and increased levels of inflammation , that may affect cancer risk [ 35 , 37 ] . ltpa may also improve hormonal profiles [ 38 , 39 ] , reduce systemic inflammation , and ultimately delay cancer mortality . despite the potential biological mechanisms of physical activity in cancer biology , associations were not significant for all levels of ltpa in the whole population in this study . some inherent limitations of the nhanes iii survey design and assessment methods for physical activity could have contributed to measurement error and the quantitatively weak findings . it has been hypothesized that the time course of risk factors along the continuum of the cancer process is important and previous studies suggest that physical activity after the diagnosis of cancer influences cancer mortality [ 29 , 41 ] . changes in ltpa patterns over time and engagement in ltpa after cancer diagnosis during the follow - up period were not captured , potentially biasing the results towards the null . next , physical activity was self - reported and was therefore vulnerable to recall bias due to under- or overreporting their level of ltpa . further , the nhanes iii dataset was not well powered to investigate site - specific cancer mortality . lastly , the results of this study might be an underestimation of the associations , because the exposure data were collected in 19881994 and the prevalence of ir as well as the proportion of physically inactive persons have increased in the past two decades [ 4345 ] , emphasizing the importance of physical activity in the current context . in conclusion , this study uniquely utilizes a large , nationally representative sample of us adults and assesses the interrelationship between ltpa , obesity , and ir , two hypothesized risk factors of cancer mortality in the previous literature . the results suggest that the protective effects offered by physical activity against cancer mortality may be realized through the maintenance of normal metabolic function and may thereby serve a potential cancer control tool . if confirmed in additional epidemiologic studies , these findings may have important public health implications in the context of the high rates of insulin resistance and cancer mortality and a large proportion of persons with sedentary lifestyles in the usa . further research is also required to determine the critical periods of exposure to physical activity during the life course with exposure measures before and after cancer diagnosis in relation to cancer outcomes in prospective studies .

longitudinal associations between leisure - time physical activity ( ltpa ) and overall cancer mortality were evaluated within the third national health and nutrition examination survey ( nhanes iii ; 19882006 ; n = 15,535 ) . mortality status was ascertained using the national death index . self - reported ltpa was divided into inactive , regular low - to - moderate and vigorous activity . a frequency - weighted metabolic equivalents ( mets / week ) variable was also computed . hazard ratios ( hrs ) and 95% confidence intervals ( ci ) were calculated for overall cancer mortality in the whole sample , by body mass index categories and insulin resistance ( ir ) status . nonsignificant protective associations were observed for regular low - to - moderate and vigorous activity , and for the highest quartile of mets / week ( hrs range : 0.660.95 ) . individuals without ir engaging in regular vigorous activity had a 48% decreased risk of cancer mortality ( hr : 0.52 ; 95% ci : 0.280.98 ) in multivariate analyses . conversely , nonsignificant positive associations were observed in people with ir . in conclusion , regular vigorous activity may reduce risk of cancer mortality among persons with normal insulin - glucose metabolism in this national sample .

the lines show the simulated xp spectrum from the band structure results . calculated partial density of states of ( b ) zr 4@xmath7 @xmath1 ( dashed line ) & @xmath8 ( solid line ) symmetries , and ( c ) b 2@xmath9 ( solid line ) and 2@xmath6 ( dashed line ) states . ] valence band spectra obtained using he ii and al @xmath10 excitation energies are shown in fig . 2(a ) exhibiting three distinct features marked by a , b and c beyond 2 ev binding energies . the intensities between 6 - 10 ev binding energies represented by b are prominent in the he ii spectrum , while the relative intensity between 3 - 4 ev binding energies represented by a is enhanced in the @xmath11-ray photoemission ( xp ) spectrum . such change in intensity in the angle integrated spectra may be attributed to the matrix elements associated to different constituent states forming the eigenstates of the valence band , which is a sensitive function of the photon energy @xcite . therefore , the photoemission cross section will vary with the photon energy that can be used to identify the orbital character of the energy bands . considering this feature of the technique , the spectral feature , b can be attributed to dominant b 2@xmath6 orbital character and the feature a to zr 4@xmath7 orbital character . energy band structure of zrb@xmath0 has been calculated within the local density approximations ( lda ) . the calculated partial density of states ( pdos ) corresponding to zr 4@xmath7 & 5@xmath9 , and b 2@xmath9 & 2@xmath6 states are shown in fig . 2(b ) and 2(c ) , respectively . zr 5@xmath9 contribution appears in the energy range of 5 - 7.5 ev above the fermi level with negligible contributions in the energy window studied here as shown by thick solid line in fig . b 2@xmath9 contributions appear beyond 6 ev binding energies . dominant contribution from b 2@xmath6 pdos appears between 1.5 to 10 ev binding energies . the center of mass of the b 2@xmath6 pdos ( considering both occupied and unoccupied parts ) appears around 1.9 ev binding energy . the center of mass of the entire zr 4@xmath7 pdos appear around 2.8 ev above @xmath12 , which is about 4.7 ev above the center of mass of the b 2@xmath6 pdos . thus , an estimate of the charge transfer energy could be about 4.7 ev in this system . the ground state is metallic with flat density of states across @xmath12 arising due to highly dispersive energy bands in this energy range . the density of states at @xmath12 possess close to 2:1 intensity ratio of the b 2@xmath6 and zr 4@xmath7 orbital character . contributions and that on the right panel shows @xmath8 contributions . ] the electronic states with @xmath1 and @xmath8 symmetries , shown in fig . 2(b ) , exhibit almost overlapping center of mass suggesting negligible crystal field splitting ( crystal field splitting @xmath13 100 mev ) . the energy bands are shown in fig . 3 . @xmath8 bands are relatively narrow and exhibit a gap at @xmath12 . the intensity at @xmath12 essentially have highly dispersive @xmath1 symmetry . using the above band structure results , we calculated the xp spectrum considering the photoemission cross section of the constituent partial density of states as discussed later in the method section . the calculated spectrum shown by solid line in fig . 2(a ) exhibits an excellent representation of the experimental xp spectrum . it is clear that the feature , c in the energy range 10 - 14 ev corresponds to photoemission signal from b 2@xmath9 levels . the features , a and b arise due to hybridized b 2@xmath6 - zr 4@xmath7 states . the relative contribution from zr 4@xmath7 states is higher for the feature a. and ( b ) b 2@xmath6 pdos obtained from lda and lda+@xmath14 calculations ( @xmath15 = 6 ev ) . ( c ) zr 4@xmath7 and ( d ) b 2@xmath6 pdos obtained @xmath15 = 6 ev and @xmath16 = 4 ev . ] in order to probe the electron correlation induced effect on the electronic structure , we have carried out electron density of states calculation using finite electron correlation among the zr 4@xmath7 electrons , @xmath15 as well as that among b 2@xmath6 electrons , @xmath16 . in figs . 4(a ) and 4(b ) , we show the calculated results for zr 4@xmath7 and b 2@xmath6 pdos with @xmath15 = 0 ( solid line ) and 6 ev ( dashed line ) for the zr 4@xmath7 electrons . even the large value of @xmath15 of 6 ev does not have significant influence on the occupied part of the electronic structure , while an energy shift is observed in the unoccupied part . such scenario is not unusual considering the large radial extension of 4@xmath7 orbitals and poor occupancy @xcite . the inclusion of an electron correlation , @xmath16 of upto 4 ev for b 2@xmath6 states exhibits insignificant change in the results . considering zr being a heavy element , we carried out similar calculations including spin - orbit interactions and did not find significant modification in the results - we have not shown these later results to maintain clarity in the figure . all these theoretical results suggest that consideration of electron correlation within the lsda+@xmath14 method has insignificant influence in the occupied part of the electronic structure of this system . we now investigate the spectral changes near @xmath12 with high energy resolution in fig . the spectral density of states ( sdos ) are calculated by symmetrizing the experimental spectra ; @xmath17 and shown in figs . 5(c ) and 5(d ) . such an estimation of sdos is sensitive to the definition of the fermi level , which is carefully derived at each temperature by the fermi cutoff in the valence band spectra for silver mounted on the sample holder in electrical connection with the sample and measured using identical experimental conditions . the other effect is the asymmetry across the fermi level . this can be addressed by obtaining the sdos by the division of the resolution broadened fermi - dirac distribution function . the results are shown in figs . 5(e ) and 5(f ) for he ii and he i spectra , respectively . clearly , the sdos obtained following the later procedure exhibits symmetric sdos across @xmath12 . the 30 k and 10 k data exhibit large noise above @xmath12 due to the division of negligibly small intensities by small numbers arising from fermi - dirac function at these temperatures . these results demonstrate the reliability of sdos extraction procedures and also indicate signature of particle - hole symmetry in this system . , ( b ) @xmath18 , and ( c ) @xmath19 . spectral density of states from ( d ) he i and ( e ) he ii spectra . the lines represent the spectral functions simulated to fit the experimental spectra . ] the spectral lineshape near the fermi level often provides important information about the thermodynamic properties of the systems . for example , a lineshape dependence of @xmath20 corresponds to fermi liquid behavior @xcite - absence of linearity of sdos with @xmath20 shown in fig . 6(a ) indicates a deviation from such a behavior in the present case . the decrease in intensity at @xmath12 with the decrease in temperature may arise due to the disorder induced localization of the electronic states . altshuler & aronov showed that the charge disorder in a correlated system leads to @xmath21 dependence of the density of states near fermi level @xcite , which has been proved employing photoemission spectroscopy @xcite . in the present case , a plot of sdos with @xmath22 shown in fig . 6(b ) exhibits deviation from linearity . interestingly , the curvatures at the exponents of 0.5 and 2 are opposite indicating an intermediate exponent for the present system . the simulation of sdos as a function of @xmath23 with @xmath24 exhibits linear dependence with energy for all the temperatures studied ( see fig . 6(c ) ) . such a behavior in a conventional superconductor is curious . most interestingly , in fig . 6(c ) , all the data below 150 k superimpose exactly and correspond to the same energy scale , while the data at 300 k exhibit similar energy dependence with a different slope . these results suggest signature of an incipient phase transition at an intermediate temperature . the sdos at @xmath12 is intense and flat at 300 k with large dispersion of the bands and correspond to a good metallic phase consistent with the band structure results . the decrease in temperature introduces a dip at @xmath12 . the dip gradually becomes more prominent with the decrease in temperature . the same scenario is observed in both , he i and he ii spectra indicating this behavior to be independent of the photon energy used . this dip may be attributed to a pseudogap appearing at low temperatures @xcite . although the probed lowest temperature is slightly above @xmath2 , the dip grows monotonically with the decrease in temperature - a large suppression of the spectral weight at the fermi level is observed at 10 k indicating relation of this dip to the superconducting gap . in order to estimate the energy gap in these spectral functions , we used a phenomenological self - energy , @xmath25 following the literature @xcite . @xmath26\ ] ] where @xmath27 represents the gap size . the first term is the energy independent single particle scattering rate and the second term is the bcs self energy . @xmath28 represents the inverse electron pair lifetime . the spectral functions , the imaginary part of the green s functions , were calculated as follows . @xmath29 $ ] , where @xmath30 and @xmath31 are the real and imaginary part of the self energy . we find that a finite value of @xmath28 is necessary to achieve reasonable representation of the experimental data . the simulated and experimental spectral density of states are shown by superimposing them in figs . 6(d ) and 6(e ) for the he i and he ii spectra , respectively . evidently , the simulated spectra provide a remarkable representation of the experimental spectra . the experimental and calculated band structure results suggest significant hybridization between zr 4@xmath7 and b 2@xmath6 states leading to similar energy distribution of the pdos . here , the eigenstates are primarily constituted by the linear combination of the zr 4@xmath7 and b 2@xmath6 states . the antibonding bands possess large zr 4@xmath7 orbital character and appear in the unoccupied part of the electronic structure @xcite . the energy bands below @xmath12 forming the valence band are the bonding eigenstates consisting of dominant 2@xmath6 orbital character . the covalency between these states could be attributed to the large radial extension of the 4@xmath7 orbitals overlapping strongly with the neighboring states as also observed in other 4@xmath7 systems @xcite . the calculated results within the local density approximation are consistent with the experimental spectra - subtle differences between the experiment and theory could not be captured via inclusion of electron correlation and/or consideration of spin - orbit coupling in these lda calculations . the band structure results exhibit two important features - ( i ) the energy bands with @xmath1 symmetry are highly dispersive compared to @xmath8 bands and ( ii ) the crystal field splitting is negligible . as shown in fig . 1 , the b@xmath0 dodecahedrons form an octahedra around zr sites with the center of mass of the b@xmath0 units at the edge centers of the unit cell . the size of the dodecahedrons are quite large with no boron situating on the unit cell edge . thus , the overlap of b 2@xmath6 orbitals with the @xmath1 orbitals is significantly enhanced due to the proximity of borons along the face diagonals , while that with the @xmath8 orbitals is reduced leading to a comparable crystal field potential on both the orbitals . the larger hybridization with the @xmath1 orbitals are also manifested by the large dispersion of the @xmath1 bands spanning across the fermi level while @xmath8 bands are relatively more localized . from these calculations , the effective valency of zr was found to vary between ( + 2.4 ) to ( + 2.5 ) depending on the electron interaction parameters such as correlation strength , spin orbit coupling _ etc_. bands crossing the fermi level are shown by lines . the symbols represent the first derivative of the same energy bands . the arrows show the fermi level crossings . ] the fermi level is located almost at the inflection points of each of the energy band crossing @xmath12 as shown in fig . this is verified by investigating the first derivative of the energy bands shown by the symbols in the figure . the arrows in the figure indicate fermi level crossing and corresponding point in the first derivative curves . evidently , the band crossing correspond to an extremum in the derivative plot . the inflection point is the point , where the curve changes its curvature that corresponds to a change in the character of the conduction electrons ( the fermi surface ) from hole - like to electron - like behavior . this behavior is termed as lifschitz transition @xcite . thus , this material appear to be lying in the proximity of the lifschitz transition as also observed in various exotic unconventional superconductors such as fe - pnictides @xcite . due to the lack of cleavage plane and hardness of the sample , the fermi surface mapping of this sample could not be carried out to verify this theoretical prediction experimentally . it is well known that the band structure calculations captures the features in the electronic structure well in the weakly correlated systems as also found in the present case suggesting possibility of such interesting phenomena in this system . we hope , future studies would help to enlighten this issue further . , inverse pair lifetime , @xmath28 and single particle scattering rate , @xmath32 as a function of temperature . the open and close symbols correspond to the fitting of he i and he ii data , respectively . ] the high resolution spectra close to the fermi level indeed exhibit deviation from fermi liquid behavior - a suggestive of quantum instability in this system as expected from the above results . r. lortz _ et al . _ @xcite showed that the resistivity of zrb@xmath0 exhibits linear temperature dependence in a large temperature range of 50k - 300k . the resistivity below 50k of the normal phase is complex and does not show @xmath33-dependence . both , the resistivity and specific heat data exhibit signature of anharmonic mode of zr - vibrations . all these observations indicate complexity of the electronic properties , different from a typical fermi - liquid system consistent with the photoemission results . a dip appears at the fermi level at temperatures much higher than the superconducting transition temperature reminiscent of a pseudogap feature . in order to investigate this further , we study the fitting parameters simulating the spectral functions in fig . the energy gap , @xmath27 is found to be about 7.3 mev and remains almost unchanged in the whole temperature range studied . this gap is significantly larger than the value predicted ( 1 - 2 mev ) considering bcs behavior . the magnitude of @xmath34 , which is a measure of single particle scattering rate , is quite large and found to decrease with the decrease in temperature . on the other hand , @xmath35 , the inverse pair lifetime is found to be significant and smaller than 2@xmath27 suggesting proximity to a bcs limit for this system . @xmath28 exhibits temperature dependence quite similar to that of @xmath32 . the decrease in @xmath28 manifests gradual enhancement of the electron pair lifetime with the decrease in temperature that eventually leads to the superconducting phase upon attaining coherence among the pairs . thus , the temperature in the vicinity of 70 k exhibiting the onset of pair formation could be the critical temperature , @xmath36 in this system . the observation of the signature of an energy gap and finite electron pair lifetime above @xmath2 is quite similar to that observed for under - doped cuprates@xcite and is an indication of precursor effect in this system . clearly , the electronic structure of this system is complex , appears to be at the crossover of bcs and unconventional behaviors and further studies are required to understand the origin of pseudogap & unusual spectral lineshape . in summary , we studied the electronic structure of zrb@xmath0 , predicted to be a complex conventional superconductor employing high resolution photoemission spectroscopy and _ ab initio _ band structure calculations . the valence band spectra exhibit multiple features with dominant b 2@xmath6 orbital character close to the fermi level . the experimental results could be captured reasonably well within the local density approximations . the electronic states close to fermi level have @xmath1 symmetry and the filling of the bands is in the proximity of lifschitz transition . the spectral lineshape near the fermi level in the high resolution spectra exhibit deviation from typical fermi liquid behavior . a dip at the fermi level emerges above the superconducting transition temperature and gradually becomes prominent at lower temperatures . the analysis of the spectral functions within the phenomenological descriptions suggests finite electron pair lifetime above @xmath2 as a signature of a precursor effect to the superconducting transition in this system . single crystals of zrb@xmath0 were grown by floating zone technique in a crystal systems incorporated ( csi ) four - mirror infrared image furnace in flowing high purity ar gas at a pressure of 2 bar @xcite . the quality of the crystal was confirmed and orientation was determined from @xmath11-ray laue - diffraction images . the magnetization measurements using a qunatum design mpms magnetometer show a sharp superconducting transition temperature , @xmath37 of 6.1 k @xcite . the photoemission measurements were performed using a gammadata scienta r4000 wal electron analyzer and monochromatic laboratory photon sources . @xmath38-ray photoemission ( xp ) and ultraviolet photoemission ( up ) spectroscopic measurements were carried out using al @xmath10 ( 1486.6 ev ) , he ii ( 40.8 ev ) and he i ( 21.2 ev ) photon energies with the energy resolution set to 400 mev , 4 mev and 2 mev , respectively . the melt grown sample was very hard and possesses no cleavage plane . therefore , the sample surface was cleaned using two independent methods ; top - post fracturing and scraping by a small grain diamond file at a vacuum better than 3@xmath3910@xmath40 torr . both the procedures results to similar spectra with no trace of impurity related signal in the photoemission measurements . the measurements were carried out in analyzer transmission mode at an acceptance angle of 30@xmath41 and reproducibility of all the spectra was ensured after each surface cleaning cycle . the temperature variation down to 10 k was achieved by an open cycle he cryostat from advanced research systems , usa . the energy band structure of zrb@xmath0 was calculated using full potential linearized augmented plane wave method within the local density approximation ( lda ) using wien 2k software @xcite . the energy convergence was achieved using 512 @xmath42-points within the first brillouin zone . the lattice constant of 7.4075 was used considering the unit cell shown in fig . 1 @xcite . in order to introduce electron - electron coulomb repulsion into the calculation , we have employed lda+@xmath14 method with an effective electron interaction strength , @xmath43 ( @xmath44 ; @xmath45 = hund s exchange integral ) setting @xmath45 = 0 following anisimov et al.@xcite . consideration of finite @xmath45 did not have significant influence on the results . we have carried out the calculations for various values of electron correlation upto 6 ev for zr 4@xmath7 electrons and 4 ev for b 2@xmath6 electrons . spin - orbit interactions among the zr 4@xmath7 electrons are also considered for the calculations . to calculate the @xmath11-ray photoemission spectrum , we have multiplied the partial density of states obtained by the band structure calculations by the corresponding photoemission cross sections for al @xmath10 energy . these cross - section weighted pdos is convoluted by two lorentzians with the energy dependent full width at half maxima ( fwhm ) for the hole & electron lifetime broadenings and a gaussian with fwhm representing the resolution broadening . the sum of these spectral functions provides the representation of the experimental valence band spectrum . the authors , k. m. and n. s. acknowledge financial support from the department of science and technology under the swarnajayanti fellowship programme . one of the author , g. b. wishes to acknowledge financial support from epsrc , uk ( ep / i007210/1 ) . vishik , i. m. et al . arpes studies of cuprate fermiology : superconductivity , pseudogap and quasiparticle dynamics . _ new j. phys . _ * 12 * , 105008 ( 2010 ) . timusk , t. & statt , b. the pseudogap in high - 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we investigate the electronic structure of a complex conventional superconductor , zrb@xmath0 employing high resolution photoemission spectroscopy and _ ab initio _ band structure calculations . the experimental valence band spectra could be described reasonably well within the local density approximation . energy bands close to the fermi level possess @xmath1 symmetry and the fermi level is found to be in the proximity of quantum fluctuation regime . the spectral lineshape in the high resolution spectra is complex exhibiting signature of a deviation from fermi liquid behavior . a dip at the fermi level emerges above the superconducting transition temperature that gradually grows with the decrease in temperature . the spectral simulation of the dip and spectral lineshape based on a phenomenological self energy suggests finite electron pair lifetime and a pseudogap above the superconducting transition temperature . the relationship between pseudogap phase and superconductivity in high temperature superconductors is an issue of discussion for many years now @xcite . while one school believes that the pseudogap arises due to some hidden order and/or effects not associated to superconductivity , the other school attributes pseudogap to the electron pair formation above the transition temperature , @xmath2 as a precursor to the superconducting gap that leads to superconductivity upon establishment of the coherence among the electron pairs at @xmath2 . independent of these differences , it is realized that electron correlation plays a significant role in the occurrence of pseudogap phase in these unconventional superconductors @xcite . several questions are being asked on whether the pseudogap phase is specific to unconventional superconductors , electron correlation or low dimensionality is a necessity for such phase _ etc_. . ( b ) b@xmath0 units are contracted to visualize the isolated b@xmath0 clusters with better clarity . ] apart from these issues , the quest of new superconducting compounds resulted into the discovery of new materials such as cubic hexane , @xmath3b@xmath4 @xcite and dodecaborides , @xmath3b@xmath0 ( @xmath3 = sc . y , zr , la , lu , th ) those attracted much attention due to their interesting electronic properties @xcite . zrb@xmath0 is one such compound exhibiting relatively high superconducting transition temperature of 6 k in the mb@xmath0 family @xcite . it forms in cubic structure as shown in fig . 1 . in fig . 1(a ) , the real lattice positions are shown with the correct bond lengths and atom positions . although , the structure appears to be complex , it is essentially a rock salt structure constituted by two interpenetrated fcc lattices formed by zr and b@xmath0 units as demonstrated in fig . 1(b ) by compressing the b@xmath0 units for clarity . various transport and magnetic measurements suggest a bardeen - cooper - schriefer ( bcs ) type superconductivity in this material , which is termed as conventional superconductivity . since , zr atoms are located within the huge octahedral void space formed by the b@xmath0 units , the superconductivity in these materials could conveniently be explained by the electron - phonon coupling mediated phenomena involving primarily low energy phonon modes associated with the vibration of zr atoms @xcite . the electronic properties of zrb@xmath0 manifest plethora of conflicts involving the mechanism of the transition . for example , there are conflicts on whether it is a type i or type ii superconductor @xcite , whether it possesses single gap @xcite or multiple gaps @xcite , _ etc . _ interestingly , gasparov _ et al_. @xcite found that superfluid density of zrb@xmath0 exhibits unconventional temperature dependence with pronounced shoulder at @xmath5 0.65 . in addition , they find different superconducting gap and transition temperatures for different energy bands , and the values of the order parameter obtained for @xmath6 and @xmath7 bands are 2.81 and 6.44 , respectively . detailed magnetic measurements reveal signature of meissner , mixed and intermediate states at different temperatures and magnetic fields @xcite . some of these variances were attributed to surface - bulk differences in the electronic structure @xcite , the superconductivity at the sample surface @xcite _ etc_. evidently , the properties of zrb@xmath0 is complex despite exhibiting signatures of bcs type superconductivity . here , we probed the evolution of the electronic structure of zrb@xmath0 employing high resolution photoelectron spectroscopy . the experimental results exhibit spectral evolution anomalous to conventional type superconductor and signature of pseudogap prior to the onset of superconductivity .

In certain areas, “you could absolutely consider it a rebooting, getting the system back to the way it used to be,” said fire ecologist Andrea Thode of Northern Arizona University. “But where there’s a high-severity fire in a system that wasn’t used to having high-severity fires, you’re creating a new system.” Some parts of Yosemite may be radically altered, entering entire new ecological states. Yet others may be restored to historical conditions that prevailed for thousands of years from the last Ice Age’s end until the 19th century, when short-sighted fire management disrupted natural fire cycles and transformed the landscape. For nearly two weeks, the nation has been transfixed by wildfire spreading through Yosemite National Park, threatening to pollute San Francisco’s water supply and destroy some of America’s most cherished landscapes. As terrible as the Rim Fire seems, though, the question of its long-term effects, and whether in some ways it could actually be ecologically beneficial, is a complicated one. Decades- and centuries-old seeds, which have remained dormant in the ground awaiting a suitable moment, will be cracked open by the heat, explained Thode. Exposed to moisture, they’ll begin to germinate and start a process of vegetative succession that results again in forests. The Rim Fire may offer some of both patterns. At high elevations, vegetatively dominated by shrubs and short-needled conifers that produce a dense, slow-to-burn mat of ground cover, fires historically occurred every few hundred years, and they were often intense, reaching the crowns of trees. In such areas, the current fire will fit the usual cycle, said Thode. Fire is a natural, inevitable phenomenon, and one to which western North American ecologies are well-adapted, and even require to sustain themselves. The new fires, though, fueled by drought, a warming climate and forest mismanagement — in particular the buildup of small trees and shrubs caused by decades of fire suppression — may reach sizes and intensities too severe for existing ecosystems to withstand. The Rim Fire now covers 300 square miles, making it the largest fire in Yosemite’s recent history and the sixth-largest in California’s. It’s also the latest in a series of exceptionally large fires that over the last several years have burned across the western and southwestern United States. At middle elevations, where most of the Rim Fire is currently concentrated, a different fire dynamic prevails. Those forests are dominated by long-needled conifers that produce a fluffy, fast-burning ground cover. Left undisturbed, fires occur regularly. “Up until the middle of the 20th century, the forests of that area would burn very frequently. Fires would go through them every five to 12 years,” said Carl Skinner, a U.S. Forest Service ecologist who specializes in relationships between fire and vegetation in northern California. “Because the fires burned as frequently as they did, it kept fuels from accumulating.” A desire to protect houses, commercial timber and conservation lands by extinguishing these small, frequent fires changed the dynamic. Without fire, dead wood accumulated and small trees grew, creating a forest that’s both exceptionally flammable and structurally suited for transferring flames from ground to tree-crown level, at which point small burns can become infernos. Though since the 1970s some fires have been allowed to burn naturally in the western parts of Yosemite, that’s not the case where the Rim Fire now burns, said Skinner. An open question, then, is just how big and hot it will burn. Where the fire is extremely intense, incinerating soil seed banks and root structures from which new trees would quickly sprout, the forest won’t come back, said Skinner. Those areas will become dominated by dense, fast-growing shrubs that burn naturally every few years, killing young trees and creating a sort of ecological lock-in. Aerial diagram (above) and three-dimensional recreation (below) of 10-acre plot prior to logging in 1929 (left) and in 2008, after 79 years of fire suppression (right). (USDA/USFS/Pacific Southwest Research Station) If the fire burns at lower intensities, though, it could result in a sort of ecological recalibration, said Skinner. In his work with fellow U.S. Forest Service ecologist Eric Knapp at theStanislaus-Tuolumne Experimental Forest, Skinner has found that Yosemite’s contemporary, fire-suppressed forests are actually far more homogeneous and less diverse than a century ago. The fire could “move the forests in a trajectory that’s more like the historical,” said Skinner, both reducing the likelihood of large future fires and generating a mosaic of habitats that contain richer plant and animal communities. “It may well be that, across a large landscape, certain plants and animals are adapted to having a certain amount of young forest recovering after disturbances,” said forest ecologist Dan Binkley of Colorado State University. “If we’ve had a century of fires, the landscape might not have enough of this.” As of now it’s not known which parts of Yosemite have burned at tipping-point levels and which have stayed within historical, possibly rejuvenating parameters. That will become apparent in years to come. In the meantime, said Binkley, the Rim Fire and other megafires of recent years have demonstrated that fire should not always be fought. “If you want to preserve something, you have to put it in a jar and pickle it. If you have a living forest, getting older and older, it’s not something we have an option to conserve in an unchanging way,” he said. “Some fires are going to be necessary if we want to sustain these old forests.” ||||| Crews have pushed forward with building containment lines around the wildfire in and around Yosemite National Park as authorities lift evacuation orders and advisories for several Sierra Nevada communities once threatened by the massive blaze. In this photo provided by the U.S. Forest Service, firefighters hose down a hotspot near a ranger station as they fight the Rim Fire in Yosemite National Park in California Sunday, Sept. 1, 2013. The... (Associated Press) In this photo provided by the U.S. Forest Service, members of the Horseshoe Meadow Interagency Hotshot Crew, from Miramonte, Calif., walk near a controlled burn operation as they fight the Rim Fire near... (Associated Press) In this photo provided by the U.S. Forest Service, members of the Roosevelt Interagency Hotshot crew, from Fort Collins, Colo., gear up for a controlled burn operation as they fight the Rim Fire near... (Associated Press) In this photo provided by the U.S. Forest Service, fire crew members stand watch near a controlled burn operation as they fight the Rim Fire near Yosemite National Park in California Sunday, Sept. 1,... (Associated Press) In this photo provided by the U.S. Forest Service, fire crew members stand watch near a burn area as they fight the Rim Fire near Yosemite National Park in California Sunday, Sept. 1, 2013. The massive... (Associated Press) In this photo provided by the U.S. Forest Service, a firefighter walks near a burn area during operations against the Rim Fire near Yosemite National Park in California Sunday, Sept. 1, 2013. The massive... (Associated Press) In this photo provided by the U.S. Forest Service, fire crew members stand watch near a controlled burn operation intended to protect the Yosemite Institute educational center as they fight the Rim Fire... (Associated Press) Officials said they still are investigating the cause of the fire, which started 18 days ago in an isolated area of the Stanislaus National Forest and has burned nearly 370 square miles _ the fourth biggest recorded wildfire in California. With higher humidity and lower temperatures, the fire reached 80 percent containment, prompting the sheriff's offices in Tuolumne and Mariposa counties to lift evacuation advisories for communities with several thousand structures in the fire's path. Officials said 111 structures, including 11 homes, have been destroyed. More than 4,300 firefighters are still battling the blaze. Although no cause has been announced, one local fire chief speculated the fire might have ignited in an illegal marijuana grow. Chief Todd McNeal of the Twain Harte Fire Department told a community group recently that there was no lightning in the area, so the fire must have been caused by humans. "We don't know the exact cause," he said in a talk that was posted Aug. 23 on YouTube. "Highly suspect it might have been some sort of illicit grove, a marijuana-grow-type thing, but it doesn't really matter at this point." The video was first reported Saturday by the San Jose Mercury News. Officials overseeing the fire suppression effort would not comment on the statement and would only say that the cause is still under investigation. "There has been some progress but there are no additional details at this time," said Rena Escobedo, a spokeswoman with the Rim Fire incident command team. The U.S. Forest Service is leading the investigation. McNeal could not be reached for comment Tuesday. Whether a marijuana grow or something else was the cause of the fire will take a long time to determine, said Doug Allen, a retired division chief in charge of law enforcement for the California Department of Forestry and Fire Protection in Southern California. Allen said investigators generally follow char marks on trees and rocks to help find the fire's point of origin, then mark off the territory into grids that are searched for clues. A lightning strike, for example, might have melted sand into glass. "Everything will have carbon stains that will tell them which direction it came from," Allen said. "You won't find the point of origin on every fire. Maybe a bulldozer has driven over where it started and you're out of luck." Illegal marijuana grows in national parks and forests have tormented federal land managers for years. Growers hike into remote canyons with poisons and irrigation lines and set up camp for months. The poisons kill wildlife and seep into streams and creeks. The growers leave tons of garbage behind. The three top causes of wildfire in California are equipment use, such as a lawnmower blade hitting a rock or a vehicle's malfunctioning catalytic converter, plus debris burning and arson.

– The Atlantic goes looking for some silver lining to the Yosemite wildfire, and finds this: Carl Skinner, a US Forest Service ecologist, has discovered that the forest has been altered over the past 100 years due to human intervention into naturally occurring forest fires, becoming less diverse. So the current Rim fire could "reboot" the system back to its historical roots, allowing for a wider variety of habitats where long-dormant plants can once again thrive. "If you have a living forest, getting older and older, it’s not something we have an option to conserve in an unchanging way,” says an ecologist from Colorado State University. “Some fires are going to be necessary if we want to sustain these old forests.” It's not quite that simple, though, says Skinner—this fire isn't natural and could be so intense that it damages seeds and tree roots to the point of no return. In other fire-related silver lining, the blaze is now 80% contained, and the evacuation order has been lifted in several nearby communities, reports the AP.

diabetic macular edema is the leading cause of significant loss of visual acuity in patients with diabetic retinopathy . it results from the damage and increased permeability of macular capillaries in the course of hypoxia , leading to increased levels of antivascular endothelial growth factor ( vegf ) and release of inflammatory factors such as cytokines , which result in the loss of endothelial cells and pericytes . the treatment of diabetic macular edema is still difficult and involves a high percentage of failures . the gold standard for laser photocoagulation can indeed maintain and even improve the long - term observation of patients with baseline visual acuity , but in others it is ineffective , and , besides , it leads to reduction in the field of vision , impaired colour perception , and reduced feeling of contrast [ 24 ] . used interchangeably , but often in addition to laser , steroids increase the chance of improving visual acuity in patients with dme [ 3 , 5 , 6 ] . corticosteroids demonstrating strong anti - inflammatory properties reduce the formation of secondary macular edema of various etiologies by reducing capillary permeability , inhibiting fibrin deposition , and retarding the loss of endothelial tight junction proteins . restricting the migration of leukocytes inhibits the formation of vegf factor , prostaglandins , and other proinflammatory cytokines . it seems that the route of administration of steroid drugs is crucial for the effectiveness of their action . orally administered , with the highest concentration in serum , they may cause a significant number of side effects such as cushing 's syndrome , osteoporosis , or exacerbation of diabetes and , at the same time , low levels of steroid concentration in the vitreous . the topical , subconjunctival , and peribulbar method of administration provides a relatively high concentration in the vitreous and in serum ; the risk of complications of general administration is similarly high [ 8 , 9 ] . the use of drugs administered directly into the vitreous can result in achieving the appropriate concentration of the drug directly at the site of the disease with decreasing systemic side effects . its effect is six times stronger than that of triamcinolone acetonide . due to the short half - life of dexamethasone in the vitreous , triamcinolone acetate ( kenalog-40 , bristol - myers squibb , princeton , nj ) is widely used in the treatment of secondary macular edema , including diabetic retinopathy , of which lipophilic crystals are deposited in the vitreous for several months . however , this form of triamcinolone acetonide deposit , administered at a dose of 4 mg in a single injection , did not provide a constant level of drug in the vitreous even during the initial period of observation and was associated with side effects such as increased intraocular pressure and steroid cataracts [ 11 , 12 ] . introduction in 2009 of the treatment intravitreal implant dexamethasone 0.7 mg ( ozurdex allergan inc . , irvine , ca ) in the form of a copolymer of lactic acid and glycolic acid plga ( novadur allergan inc.)by the progressive biodegradation made it possible to obtain a comparable concentration in the vitreous chamber for a period of up to 180 days after a single injection . for as long as that , the drug should provide a better therapeutic effect and reduce the number of intravitreal injections of drugs with a shorter duration of action as well as reduce the risk of adverse effects associated with multiple injections and high concentration immediately after injection . this retrospective analysis was to evaluate the effectiveness of treatment of persistent diabetic macular edema with intravitreal injections of 0.7 mg dexamethasone implant ozurdex . the study comprised three male patients ( 6 eyes ) , aged on average 52 and with average diabetes duration of 13.3 years . in each eye , persistent macular edema occurred for more than six months despite the treatment of grid macular photocoagulation and antivessel growth factor ( ranibizumab ) 0.5 mg intravitreal injections . the initial and control studies evaluated the best corrected visual acuity ( bcva logmar lines ) , corrected intraocular pressure , and examination of the anterior and posterior segment of the eye with central retinal thickness measurements using optical coherent tomography spectral cirrus hd - oct zeiss . each patient received 0.3% ciprofloxacin in the eye drops four times a day two days before and four days after the treatment ( figure 3 ) . before the injection of intravitreal implant ozurdex , each of the six eyes presented significant edema of the retina treated before with grid laser photocoagulation and three intravitreal injections of anti - vegf factor . the last injection of ranibizumab 0.5 mg was performed at least 3 months before starting the treatment with ozurdex . five eyes indicated with the numbers 4 , 5 , 6 , 7 , and 8 received a single injection dose of 0.7 mg ozurdex , while one eye injection numbered 1 , 2 , and 3 received three ozurdex doses at six - month intervals ( table 1 ) . the average thickness of the retina at baseline was 632 m , the medial bcva was 0.8 logmar , and corrected intraocular pressure was 13.7 mmhg . the maximum decrease in mean retinal thickness was observed at four weeks following the treatment and was 365 m ( 267 m ) and visual acuity improved by an average of two lines and was 0.6 logmar ( figure 2 ) . a slight decrease in retinal thickness to 346.13 microns ( 18.87 microns ) and mean visual acuity of 0.65 logmar lines were observed in week 8 . at 12 weeks , the average thickness of the retina increased to 381.13 microns ( + 35 m ) and visual acuity remained stable ; however , the results of injection number 3 were excluded because of the occurrence of steroid cataract which significantly reduced visual acuity in the study eye . the largest increase in mean retinal thickness to average 528 m ( + 164 microns ) occurred at 16 weeks and average bcva was 0.614 lines bcva logmar ( figure 1 ) . five - month observation of the patients with chronic diabetic macular edema previously treated with grid photocoagulation and ranibizumab injections shows that it is not possible to obtain a continuous improvement of the local conditions in visual acuity and decrease in central retinal thickness , which has also been confirmed by other authors [ 14 , 15 ] . after 4 weeks of injections , all of our patients had a significant decrease in the central retinal thickness and improvement in visual acuity . this condition continued until 12 weeks of observation . in the four - month follow - up , all patients had a gradual increase in the central retinal thickness and their visual acuity after 5 months was similar to that of the pretreatment . in none of the treated patients after this period the central retinal thickness and in accordance with other literature , the results indicate that the greatest effectiveness of ozurdex can be seen in the first 4 weeks after administration ; it lasts for up to 12 weeks of observation and then gradually decreases . most likely , this should be associated with the decrease in the vitreous concentrations of dexamethasone released . that confirms the observation that reinjection of ozurdex after a period of six months produces a similar effect as the first injection . in our follow - up following administration of 0.7 mg dexamethasone implant , there was no increase in the intraocular pressure requiring medical treatment in any of the eyes . in one eye , there was a steroid cataract development after the third dose of 0.7 mg dexamethasone implant , which coincides with the observations of other authors . in conclusion , the intravitreal dexamethasone implant treatment of patients with persistent diabetic macular edema in whom laser photocoagulation proved to be ineffective and who , as a result , required a monthly injection of anti - vegf factors ( ranibizumab , bevacizumab ) may be a good alternative as it allows extending the interval between injections .

aims . this retrospective analysis was aimed at evaluating the effectiveness of treatment of persistent diabetic macular edema with intravitreal injections of 0.7 mg dexamethasone implant ozurdex . the study comprised three male patients ( 6 eyes ) . results . the average thickness of the retina at baseline was 632 m , the medial bcva was 0.8 logmar , and corrected intraocular pressure was 13.7 mmhg . the maximum decrease in mean retinal thickness was observed at four weeks following the treatment and was 365 m ( 267 m ) and visual acuity improved by an average of two lines and was 0.6 logmar . the largest increase in mean retinal thickness to average of 528 m ( + 164 m ) occurred at 16 weeks and the average bcva was 0.614 lines bcva logmar . in one eye , there was a steroid cataract development after the third dose of dexamethasone implant of 0.7 mg . conclusions . the intravitreal dexamethasone implant treatment of patients with persistent diabetic macular edema in whom laser photocoagulation proved to be ineffective and as a result they required a monthly injection of anti - vegf factors ( ranibizumab , bevacizumab ) may be a good alternative to extending the interval of injections . however , reinjections involve a high risk of developing poststeroid cataracts , which is not without significance in middle - aged patients .

systematic collection and curation of phenotypic descriptions began in the 1940s as textual synopses for mouse mutants ( snell 1941 ) . then , maintaining and updating text manually was easy ( very few mutants known ) and there were no electronic records requiring search mechanisms or computer - parsable formats . now there are over 24,300 mutant alleles that have been identified in mice1 with established phenotypes , representing mutant alleles in over 9,600 genes ( table 1 ) . also , there are nearly 4,700 qtl ( quantitative trait loci ) that represent genomic regions associated with particular phenotypic traits . the mouse genome informatics ( mgi http://www.informatics.jax.org ) ( blake et al . 2011 ; eppig et al . 2012 ) database , the primary international database for mouse , adds several hundred new mutant alleles with reported phenotypes to the database each month.table 1mutant allele and phenotype data in the mouse genome informatics database , mgidata typecounttotal mutant alleles ( in es cell lines and mice)738,364mutant alleles in mice24,339genes with mutant alleles14,743genes with mutant alleles in mice9,636mammalian phenotype ontology ( mp ) terms8,744genes with phenotype annotations8,903genotypes with phenotype annotations43,335total mp annotations to genotypes227,169human diseases with one or more genotypic mouse models1,148mouse genotypes modeling human diseases3,668quantitative trait loci ( qtl)4,696total recombinase ( cre)-expressing transgenes and alleles1,739data as of may 5 , 2012 , www.informatics.jax.org . new data are added to the mgi database daily ; thus , actual counts will be higher than those shown heremutant allele counts include spontaneous , induced ( e.g. , by enu ) , and genetically engineered alleles . transgenes , which are not part of the normal mouse genome , are not includedmutants present only in es cell lines versus those created in mice or made into mice from es cells are distinguished in several table counts . all phenotype - related data refer to mutations present in mice mutant allele and phenotype data in the mouse genome informatics database , mgi data as of may 5 , 2012 , www.informatics.jax.org . new data are added to the mgi database daily ; thus , actual counts will be higher than those shown here mutant allele counts include spontaneous , induced ( e.g. , by enu ) , and genetically engineered alleles . transgenes , which are not part of the normal mouse genome , are not included mutants present only in es cell lines versus those created in mice or made into mice from es cells are distinguished in several table counts . all phenotype - related data refer to mutations present in mice researchers increasingly develop sophisticated new mouse models of human disease and analyze phenotypes in mice carrying complex engineered and mutant allele combinations on multiple genetic backgrounds . the unit of annotation for a phenotype , therefore , must be the animal(s ) or genotype assessed , annotated to mp terms and accompanied by key conditional variables ( e.g. , treatment , age of onset ) . thus , the actual number of phenotype - bearing populations far exceeds the number of mutant alleles . such data maintained by continuous resynthesis of information as descriptive text are ( 1 ) impractical to maintain ; ( 2 ) unreliable to search without structured format and controlled vocabularies , producing false - negative and false - positive search errors ; and ( 3 ) not amenable to computational analyses . large - scale projects to produce a complete set of mutations for every gene in the mouse are underway using phenotype - driven mutagenesis approaches [ cf . enu ( n - ethyl - n - nitrosourea ) ] ( acevedo - arozena et al . 2008 ; clark et al . 2004 ; cook et al . gene - trap and gene - knockout programs ) ( araki et al . 2009 ; austin et al . these new data sets and the need to restructure phenotype data representation in mgi prompted transformation of text - based phenotypic descriptions into structured annotations based on the mp , which was initiated concurrently as a phenotype annotation tool in 2001 . restructuring of mgi s phenotype data included ( a ) development of a data model for phenotypes in the mgi relational database ; ( b ) development of the mp ontology ( smith and eppig 2009 ; smith et al . 2004 ) as the cornerstone for phenotype annotation ; ( c ) application of the mp ontology to ongoing curation of phenotypes in mgi and the retirement of text - based descriptions ; ( d ) development of new , robust access to phenotypes via redesigned web interfaces , tracks on the mgi mouse genome browser ( http://gbrowse.informatics.jax.org/cgi-bin/gbrowse/mouse_current ) , and contribution of data to other genome browser resources such as university of california santa cruz ( ucsc , http://genome.ucsc.edu ) , ensembl ( http://www.ensembl.org ) and ncbi ( national center for biotechnology information , http://www.ncbi.nlm.nih.gov ) ; and ( e ) development of a human disease view of mouse phenotypes utilizing mgi s annotations to omim ( online mendelian inheritance in man , http://www.omim.org ) disease terms . the significance of the mouse as a model organism , the availability of its fully sequenced genome , and the accessibility of mouse tissues for experimentation at all life - stages invite new applications and exquisite experimental manipulation to address key scientific questions . integration of experimental data using standard data descriptions and nomenclatures is of paramount importance in maximizing the value of the mouse model system . mgi has loaded large - scale data from enu phenotyping centers and laboratories and is poised to load new phenotyping data from the developing international mouse phenotyping consortium ( impc , www.mousephenotype.org ) , allowing integration of these data with data derived from individual laboratories and the biomedical literature . a common interface to phenotypes in mgi exists that allows critical phenotype and genotype comparisons . further , alignment of mouse mutant phenotypes with human disease symptoms will aid in identifying mouse genetic models with phenotypic matches as well as the currently captured experimentally demonstrated mouse models for human disease . the mp is the workhorse for standardizing phenotypic descriptions in mouse , rat , and other mammals . ontology , structured as a dag ( directed acyclic graph ) and using phenotype terms recognized by research biologists and clinicians that include simple compound concepts ( e.g. , liver hyperplasia , mp:0005141 ) and aggregate concepts ( e.g. , glomerular crescent , mp:0011506 ) ( fig . 1the mammalian phenotype ontology ( mp ) browser at mgi , showing details for the term ventricular septal defect ( mp:0010402 ) . left mgi s mp browser display shows the term name , common synonyms and acronyms , the primary mp i d , alternate ids , and the term definition . the two term paths are shown as a hierarchial tree , with paths listed in multiple sequential graphs . each term in the mp browser is followed by a link to mgi genotypes associated with that term or any children of that term . right a graphical representation of the dag structure for the term ventricular septal defect . the two alternate paths from the node cardiovascular system phenotype are shown the mammalian phenotype ontology ( mp ) browser at mgi , showing details for the term ventricular septal defect ( mp:0010402 ) . left mgi s mp browser display shows the term name , common synonyms and acronyms , the primary mp i d , alternate ids , and the term definition . the two term paths are shown as a hierarchial tree , with paths listed in multiple sequential graphs . each term in the mp browser is followed by a link to mgi genotypes associated with that term or any children of that term . right a graphical representation of the dag structure for the term ventricular septal defect . the two alternate paths from the node cardiovascular system phenotype are shown the mp is a flexible , expandable tool that can grow to accommodate the anticipated rapid increase in phenotyping data , can be applied to maximize precision and breadth of user phenotype searches , and can facilitate an efficient curation stream of incoming phenotype data . by annotating phenotypes from these data sets using mp , this stands in contrast to natural language text , where there is no restriction on the variation of term names , descriptors , or grammar , confounding data integration and limiting effectiveness of data searches . as of may 2012 , the top nodes are organized into 27 categories representing biological systems , mortality terms , and behavior , with abnormal morphological and physiological system terms at the next node level . phenotype data can be annotated at any point along the structure , depending on the detail available from information sources . each term is distinct and defined , aiding both curators and users in selecting the appropriate term for their needs . in addition , attributes and relationships among the terms are described in the form of a dag ( fig . 1 ) . this allows more flexibility than that of a simple tree , since each term can have multiple relationships to broader parent terms and more specific child terms . the more specific terms are subsumed by parent terms as one moves up the graph , which allows for more complete grouping , searching , and analysis of annotated data . multiple resources provide browser formats for viewing the mp , including the ontology lookup service ( ols , http://www.ebi.ac.uk/ontology-lookup/ontologylist.do ) , bioportal ( http://bioportal.bioontology.org/ontologies ) , and mgi s mp browser ( http://www.informatics.jax.org/searches/mp_form.shtml ) . figure 1 shows a sample page from mgi s mp browser for the phenotype term ventricular septal defect ( mp:0010402 ) . each term in the mp has a unique term name , unique accession i d , synonyms , and a definition . in mgi s mp browser , the relationship between parent and child terms is visualized by indentation of each successive level of the hierarchy . where a term has multiple parents , each path from the upper - level term to the term of interest displays as a separate hierarchy , thus effectively flattening the dag structure for web viewing . the mp file in obo format is available for download from the mgi ftp site ( ftp://ftp.informatics.jax.org/pub/reports/index.html#pheno ) ; it is also available in obo and owl formats from the open biomedical ontologies ( obo , http://www.obofoundry.org ) foundry site , ols , and bioportal . the mp is a dynamic ontology , actively used and developed by those annotating phenotypes in mouse and other species . requests for new terms , term revisions , and suggestions for structural organization modifications to the mp are frequently proposed by curators and user groups . suggestions for improvement and additions from the community are submitted through the open biomedical ontologies mammalian phenotype requests tracker system at sourceforge ( https://sourceforge.net/tracker/?atid=1109502&group_id=76834 ) or by email to [email protected] . expansion of the mp ontology and review of its hierarchical structure occurs in collaboration with new phenotype annotation projects when the need for additional granularity of terms is anticipated . in addition , collaborative review of particular systems by expert editors together with subject area specialists helps create terms and structures that are intuitive and useful to those communities . recent additions and revisions include the respiratory system , renal / urinary system , and cardiovascular system ( with significant structural reorganization ) that expanded the mp by 714 terms . to accommodate data being generated by large - scale phenotyping efforts at the wellcome trust sanger institute ( hereafter , sanger institute ) mouse genetics program ( http://www.sanger.ac.uk/mouseportal ) and from the eumorphia ( brown et al . 2010 ) european large - scale phenotyping efforts , mp added 38 new population - level lethality terms . , 196 new mp homeostasis terms now describe the results of phenotype pipeline tests generated by these centers . when new mp terms are added or revised from these annotation projects or from user requests , relevant existing phenotype annotations at mgi are triggered for review and revised to reflect the new terminology as appropriate . along with cardiovascular system term revisions , fyler codes ( keane et al . 2006 ) , a systematic , hierarchical classification of congenital heart disease ( see example in fig . 1 ) , were included as secondary ids to the primary mp i d . fyler codes align the mp to current standards of the cardiac disease research community and its representation in the research and clinical literature . these codes are consistent with the international pediatric and congenital cardiac codes ( ipccc , http://www.ipccc.net ) and enable users to search for congenital heart defects using these codes , ids , or term names , with comprehensive retrieval of information . a number of resources use the mp to describe abnormal phenotypes ( see table 2 ) , including mgi , the rat genome database ( rgd , http://rgd.mcw.edu ) , online mendelian inheritance in animals ( omia , http://omia.angis.org.au/home ) , the sanger institute mouse genetics program , mrc harwell s mousebook ( http://www.mousebook.org ) , europhenome ( http://www.europhenome.org ) , and the impc , among others . in addition , the mp is used by mouse repositories to annotate phenotype data ( or reflect downloaded mgi phenotype data ) for describing available mouse strains and stocks . these include the jackson laboratory repository ( jax mice , http://jaxmice.jax.org ) , the european mouse mutant archive ( emma , http://www.emmanet.org ) , and the mutant mouse regional resource centers ( mmrrc , http://www.mmrrc.org ) , among others.table 2urls referenced in this article ( those preceded by an asterik ( * ) incorporate mp terms for phenotype data)resourceurl*annotqtlhttp://annotqtl.genouest.orgbioportalhttp://bioportal.bioontology.org / ontologieschemical entities of biological interest ( chebi)http://www.ebi.ac.uk / chebicollaborative cross ( cc)http://csbio.unc.edu / ccstatusdisease ontology ( do)http://disease - ontology.orgdiversity outcross ( do)http://cgd.jax.org / datasets / phenotype / svensondo.shtmldrosophila genome database ( flybase)http://flybase.orgensemblhttp://www.ensembl.org*european mouse mutant archive ( emma)http://www.emmanet.org*europhenomehttp://www.europhenome.orgfoundational model of anatomy ( fma)http://sig.biostr.washington.edu / projects / fm / aboutfm.htmlgene ontology ( go)http://www.geneontology.org*gene weaverhttp://www.geneweaver.orggetting an understanding of logical definitions ( gulo)http://compbio.charite.de / svn / hpo / trunk / src / tools / gulohuman phenotype ontology ( hp)http://www.human - phenotype - ontology.orginternational classification of diseases ( icd)http://www.cdc.gov / nchs / icd.htminternational knockout mouse consortium ( ikmc)http://www.knockoutmouse.org*international mouse phenotyping consortium ( impc)http://www.mousephenotype.orginternational pediatric and congenital cardiac code ( ipccc)http://www.ipccc.net*jackson laboratory mouse repository ( jax mice)http://jaxmice.jax.orgkegg pathways databasehttp://www.genome.jp / kegg / pathway.html*mammalian phenotype enrichment analysis ( mamphea)http://evol.nhri.org.tw / phenome / index.jsp?platform = mmus*mammalian phenotype ontology ( mp ) browserhttp://www.informatics.jax.org / searches / mp_form.shtml*mammalian phenotype ontology download from mgi siteftp://ftp.informatics.jax.org / pub / reports / index.html#phenomammalian phenotype requests trackerhttps://sourceforge.net / tracker/?atid=1109502&group_id=76834medic disease vocabularyhttp://ctdbase.org / voc.go?type = diseasemedical subject headings ( mesh)http://www.nlm.nih.gov / mesh / mbrowser.html*mgi mouse genome browser ( mouse gbrowse)http://gbrowse.informatics.jax.org / cgi - bin / gbrowse / mouse_current*mousefinderhttp://www.mousemodels.org*mrc harwell mousebookhttp://www.mousebook.org*mutant mouse regional resource centers ( mmrrc)http://www.mmrrc.orgnational center for biotechnology information ( ncbi)http://www.ncbi.nlm.nih.gov*online mendelian inheritance in animals ( omia)http://omia.angis.org.au / homeonline mendelian inheritance in man ( omim)http://www.omim.orgontology lookup service ( ols)http://www.ebi.ac.uk / ontology - lookup / ontologylist.doopen biomedical ontologies ( obo)http://www.obofoundry.orgorphanethttp://www.orpha.net / consor / cgi - bin*phenohmhttp://phenome.cchmc.org / phenobrowser / phenome*phenomenethttp://phenomebrowser.net*phenomicdbhttp://www.phenomicdb.dephenotype and trait ontology ( pato)http://code.google.com / p / pato*rat genome database ( rgd)http://rgd.mcw.edureactomehttp://www.reactome.org*sanger institute mouse resources portalhttp://www.sanger.ac.uk / mouseportalsystematized nomenclature of medicine - clinical terms ( snomed - ct)http://www.ihtsdo.org / snomed - ct*toppgene : candidate gene prioritizationhttp://toppgene.cchmc.org / prioritization.jspuberon , cross - species anatomy ontologyhttp://obofoundry.org / wiki / index.php / uberon : main_page*ucsc genome browserhttp://genome.ucsc.eduuniprot - goa ( gene ontology annotation)http://www.ebi.ac.uk / goa*verygenehttp://www.verygene.comzebrafish database ( zfin ) phenotype examplehttp://zfin.org / action / phenotype / phenotype - statement?id=53698 urls referenced in this article ( those preceded by an asterik ( * ) incorporate mp terms for phenotype data ) mgi contains information on published spontaneous , induced , and genetically engineered mouse mutations ( table 1 ) , as well as contributed or downloaded data from large - scale mouse mutagenesis projects , including enu , gene trap , and knockout mutagenesis projects ( see table 3 for a list of mutagenesis projects with data integrated into mgi ) . all of these data are integrated with all of the other genomic , expression , function , tumor and pathway data in mgi to facilitate knowledge discovery and hypothesis building . the mgi website presents a mutant allele in all of its studied contexts , which is key for discerning multigenic disease models , genetic background effects , and allelic interactions . tools also are available at mgi for users who wish to separate genotypes carrying single - gene mutations from more complex genotypes such as conditional genotypes or those carrying transgenes , mutations in multiple genes , or large genomic rearrangements.table 3major mutagenesis projects contributing data to mgicenterreferenceurlenu mutagenesis projectsaustralian phenomics facility at anunelms and goodnow ( 2001)http://www.apf.edu.au / about / projects / index.shtmlcardiovascular development consortium ( cvdc)kaltman et al . ( 2010)http://www.devbio.pitt.edu / research / mouse_muta.htmlheart , lung , blood & sleep center ( hlbs)svenson et al . ( 2000)http://www.helmholtz - muenchen.de / en / idg / mouse - genetics / large - scale - mutagenesis / enu - mutagenesis / mouse mutagenesis for developmental defects ( bcm)kile et al . ( 2000)http://www.har.mrc.ac.uk / research / mutagenesis / mutagenixhoebe and beutler ( 2005)http://mutagenetix.utsouthwestern.edu / neuroscience mutagenesis consortium ( nmice)goldowitz et al . ( 2010)http://www.brc.riken.jp / lab / gsc / mouse / sloan - kettering mouse projectanderson ( 2000)https://mouse.mskcc.org / mutant / mutantbase.phptoronto centre for modeling human disease ( cmhd)cordes ( 2005)http://www.cmhd.ca / enu_mutagenesisgene trap projects ( reported in igtc , www.genetrap.org)baygenomicsstryke et al . ( 2007)http://www.helmholtz - muenchen.de / en / idg / mouse - genetics / large - scale - mutagenesis / eucommexchangeable gene trap clones ( egtc)araki et al . ( 2000)http://www.helmholtz - muenchen.de / en / idg / mouse - genetics / large - scale - mutagenesis / german - gene - trap - consortiumlexicon genetics omnibankzambrowicz et al . ( 2004)http://www.sanger.ac.uk / resources / mouse / sigtr / soriano lab gene trap databasefriedel and soriano ( 2010)http://research.mssm.edu / soriano / lab / gene_trap.htmlthe institute for genomic medicine ( tigm)hansen et al . ( 2008)http://genetrap.tigem.it / public / index.phptoronto centre for modeling human disease ( cmhd)to et al . ( 2004)http://www.cmhd.ca / genetrapknockout mouse projectsdeltagenmoore ( 2005)http://www.deltagen.comeuropean mouse mutagenesis consortium ( eucomm)auwerx et al . ( 2004)www.eucomm.orgeuropean mouse mutagenesis consortium tools ( eucommtools)skarnes et al . ( 2011)www.eucommtools.orgknockout mouse project ( komp)austin et al . ( 2004)http://www.knockoutmouse.orglexicon geneticsfriddle et al . ( 2003)http://www.lexicon - genetics.comnorth american conditional mouse mutagenesis ( norcomm)collins et al . ( 2007a)http://www.norcomm.orgthe institute for genomic medicine ( tigm)collins et al . ( 2007b)http://www.tigm.orgthis is a not an exhaustive list of major projects major mutagenesis projects contributing data to mgi this is a not an exhaustive list of major projects figure 2 shows an example of mp annotations to genotypes involving the fgfr2 mutant allele ( a mutation in the fibroblast growth factor receptor 2 gene , the first targeted mutation of this gene from the laboratory of joseph schlessinger ) . phenotype data are viewed in a matrix summary format to facilitate comparison of multiple genotypes and genetic backgrounds or by genotype . clicking the links in these sections leads to an expanded view , including terms and additional details organized by physiological system , as well as mouse disease model data and images.fig . 2example of a mgi allele detail page and associated human disease and mouse model detail page . a the fgfr2 ( a mutation in the fibroblast growth factor receptor 2 gene , the first targeted mutation from the laboratory of joseph schlessinger ) allele record shows nomenclature , a molecular description of the mutation , a phenotype summary organized by systems affected in tabular format to facilitate cross - genotype comparisons , a phenotype data by genotype section , a human disease model section , and associated references b the phenotype by genotype section expands to reveal details , including further description and citations . two different cohorts of mice carrying this allele have been analyzed , but only one has been asserted to be a model of the human disease crouzon syndrome ( omim : 123500 ) ; links to both the mgi human disease and mouse model detail page ( c ) and to omim are provided example of a mgi allele detail page and associated human disease and mouse model detail page . a the fgfr2 ( a mutation in the fibroblast growth factor receptor 2 gene , the first targeted mutation from the laboratory of joseph schlessinger ) allele record shows nomenclature , a molecular description of the mutation , a phenotype summary organized by systems affected in tabular format to facilitate cross - genotype comparisons , a phenotype data by genotype section , a human disease model section , and associated references . b the phenotype by genotype section expands to reveal details , including further description and citations . two different cohorts of mice carrying this allele have been analyzed , but only one has been asserted to be a model of the human disease crouzon syndrome ( omim : 123500 ) ; links to both the mgi human disease and mouse model detail page ( c ) and to omim are provided phenotype data associated with specific terms are retrieved in a variety of ways . a mp term or i d entered in the quick search box on any mgi page will retrieve a list of genes , alleles , and vocabulary terms . mp terms entered in the phenotype / human disease section of the advanced genes and markers query form or phenotypes query form return genes or alleles associated with genotypes annotated to that term . selecting terms in the mp browser displays links at the term level to genotypes annotated to that term or any child of that term . for example , a search in mgi using either the identifier mp:0010402 or the term name ventricular septal defect returns a list of 300 genotypes with 337 annotations representing 311 matching alleles in 232 genes , transgenes , and markers ( fig . these results include annotations to terms listed below ventricular septal defect in the hierarchy such as inlet ventricular septal defect and perimembraneous ventricular septal defect . thus , use of an ontology allows the retrieval of all information associated with a term and its children.fig . 3example of a comprehensive mgi data search result using the term ventricular septal defect . all 300 genotypes in mgi that are annotated to this term , or terms below this node in the mp , are returned . for example , genotypes annotated to the term inlet ventricular septal defect , a child term to ventricular septal defect , are seen in the results list example of a comprehensive mgi data search result using the term ventricular septal defect . all 300 genotypes in mgi that are annotated to this term , or terms below this node in the mp , are returned . for example , genotypes annotated to the term inlet ventricular septal defect , a child term to ventricular septal defect , are seen in the results list phenotype data also are retrieved from the mgi batch query form and the mgi biomart . mgi also maintains a suite of public reports containing phenotype data for download . using mgi s public reports and web services , mgi data can be exported to a variety of other data providers such as ncbi , ebi , ucsc , omim , and mouse mutant repositories , where they are incorporated to enrich those resources . comparing phenotypes among organisms as well as against human phenotypes ( and thereby with human disease ) makes it possible to discover commonalities of gene function , pathways , and mechanisms . because all organisms currently have significant gaps in the experimental knowledge of mutations and phenotypes for all genes and in the understanding of the function and interactions for each gene , comparative analyses can provide clues and direction for new experimental validation and research avenues . at present , there is no universal phenotype ontology for all species that could easily facilitate comparative phenotyping . for mammals , the mp is widely accepted and applied ( see above and table 2 ) . for human , the human phenotype ontology ( hp , http://www.human-phenotype-ontology.org ) ( robinson et al . 2008 ) , also a precomposed ontology , is actively being developed . for other model organisms , approaches vary , from species - specific vocabulary lists ( e.g. , in flybase , the drosophila model organism database , http://flybase.org ) to the eq ( entity + quality ) approach ( e.g. , in zfin , the zebrafish information network ) . in the eq approach , terms are composed de novo at the time of annotation using an entity term found in other existing ontologies [ e.g. , gene ontology ( go , http://www.geneontology.org ) , chemical entities of biological interest ( chebi , http://www.ebi.ac.uk/chebi ) ] plus a quality from the phenotype and trait ontology ( pato , http://code.google.com/p/pato ) ( gkoutos et al . 2005 ) that provides the term modifier ( e.g. , pale , enlarged , absent ) . for example , zfin combines the anatomy term pericardium ( zfa:0000054 ) with the pato term edematous ( pato:0001450 ) to create a complete phenotype ( eq ) statement pericardium edematous , abnormal ( http://zfin.org/action/phenotype/phenotype-statement?id=53698 ) . the mp ontology contains a single precomposed term pericardial edema ( mp:0001787 ) . mappings between terms of phenotype ontologies harmonize these different approaches . for the mp , direct mappings to other precomposed phenotype ontologies such as the hp , or indirect mappings of mp terms to eq statements ( mungall et al . logical definitions for mp and hp can be combined with annotations from other species databases that use eq statements to describe phenotypes , making multispecies phenotype data integration and comparisons possible ( mungall et al . importantly , logical definitions enhance the mp by establishing relationships of terms to a wider suite of interoperating ontologies . however , aggregate terms such as hydrocephaly or glomerular crescent require representation as multiple eq statements , diminishing the meaning and recognition of these scientific / clinical terminologies . ontologies developed as annotation tools ( e.g. , mp , hp , and go ) are improved by mapping concepts to a common reference framework based on existing standard ontologies ( such as the global anatomy ontology uberon , http://obofoundry.org/wiki/index.php/uberon:main_page ) ( mungall et al . maintenance of ontologies with multiple inheritance pathways becomes increasingly difficult with increased size and complexity , and they are particularly difficult to view for missing terms when additions are largely dictated by the need of curation or projects to define new terms . missing terms can be logically assumed ( i.e. , if there is a term increased x , the converse term decreased x should exist ) , although such terms might not be biologically relevant phenotypes . automatic reasoners , software tools that infer the positions of terms in a subsumption hierarchy based on logical definitions , have been exploited to identify missing or erroneous relationships and detect omissions in ontologies ( mungall et al . 2011 ) . to this end , the tool gulo ( getting an understanding of logical definitions , http://compbio.charite.de/svn/hpo/trunk/src/tools/gulo ) ( khler et al . based on the results of reasoner analysis , mp added over 300 new child parent relationships . this work also uncovered discrepancies in reference ontologies used to construct logical definitions and errors in assignment of eq statements . therefore , the use of logical definitions , coupled with software tool reasoners , automates some aspects of ontology review for completeness and term placement in the dag , although manual verification is needed to ensure accuracy and to place aggregate terms . a combination of eq statements and precomposed mp terms can reciprocally meet the needs of automated phenotype annotation pipelines and biomedical researchers interested in exploring data . eye ( ma:0000261 ) and size ( pato:0000117 ) defines the test itself , and a phenotypic observation may then be eye and decreased size ( pato:0000587 ) . ( mp:0001297 ) , or small eye , a term familiar to scientists and clinicians and used by europhenome in its web interface and biomart ( beck et al . 2009 ; morgan et al . systematic phenotyping , where many centers apply common phenotyping protocols under the same conditions ( e.g. , age , sex ) , can provide high - quality data sets for analysis and comparison . this interinstitution standardization of phenotype testing was experimented with and analyzed extensively in the last decade in the european projects of eumorphia ( brown et al . 2010 ) . the role of eumodic was to generate phenotype data from the first 500 mutant mouse knockout lines derived from the international knockout mouse project ( ikmc , http://www.knockoutmouse.org ) ( ringwald et al . the results produced by these centers are reported through the europhenome database ( morgan et al . 2010 ) and are available through a web interface or through the ikmc biomart ( oakley et al . 2011 ) . in addition , data generated by the sanger institute are available from their mouse resources portal . both of these resources perform statistical comparisons of experimentally generated mutant mouse phenotype data with control phenotype data to identify significant phenodeviants . significant results are stored and the relevant mp term for the test result is automatically applied to the mutant line . in addition to automated pipelines , data also are analyzed manually at the sanger institute and phenodeviant calls and mp terms are assigned to these results . both the europhenome and sanger institute s mouse resource portal sites allow searching and browsing for phenodeviant data using mp terms [ see review of both of these efforts in ayadi et al . mgi is undertaking the importation of these data to integrate them with all the resources that mgi offers . because these phenotype data are already associated with mp terms , as well as official gene , allele , and strain nomenclature and other standardized parameters , importation is automatable and similarly , mgi can effectively work with data sets of increasing size , such as those expected from the impc , which has a stated goal to carry out high - throughput phenotyping for over 20,000 mutant mouse lines to determine the function of every gene in the mouse genome ( brown and moore 2012 ) . mouse genotypes in mgi are annotated to human disease terms from omim ( amberger et al . for example , the fgfr2 allele is a model of the human disease crouzon syndrome ( omim id:123500 ) ( fig . links from mgi mutant allele details to both the omim record describing this condition in humans and to mgi s human disease and mouse model web pages are provided . these models are searched using the omim term or i d from the quick search box on any mgi page or the advanced genes and markers query form or phenotypes query form , or they may be browsed on the human disease vocabulary browser . omim is used as mgi s source of human genetic disease terms because it provides associated detailed descriptions of human disease and clinical synopses , associates omim disease records to human genes , and is recognized and frequently used by clinicians and biomedical researchers as an authoritative information source . given the exponentially increasing amount of complex mouse phenotype and human disease model data in mgi and elsewhere and that these data are stored in model organism databases using different methods , computational tools are required that will lead to better data mining and comparison of phenotypic data across different species . there are a number of approaches using lexical matching or ontology mapping of phenotype or clinical terms that map phenotypic similarity between mouse and human genes and variants and suggest candidate genes for human diseases [ e.g. , phenomicdb , http://www.phenomicdb.de ( groth et al . 2010 ) ; mousefinder , http://www.mousemodels.org ( chen et al . 2012 ) ; phenomenet , http://phenomebrowser.net ( hoehndorf et al . 2011 ; gkoutos et al . 2012 ; and reviewed in schofield et al . 2012 ) ] . in addition to comparing data across species , mp annotated phenotype data are used as a parameter by a number of web tools that integrate published and high - throughput data to facilitate gene discovery via enrichment analysis of gene sets or to identify candidate genes for qtl . among the tools for enrichment analysis are mamphea ( http://evol.nhri.org.tw/phenome/index.jsp?platform=mmus ) ( weng and liao 2010 ) , which enables gene enrichment analysis of genes from multiple species based exclusively on mp annotations from mouse , and toppgene ( http://toppgene.cchmc.org/prioritization.jsp ) ( chen et al . 2009 ) , a gene enrichment tool that uses mp as one of many parameters for sorting gene sets . 2012 ) , which integrates sets of biological functions ( go ) , their relations to mutant phenotypes through the mp , kegg pathways ( http://www.genome.jp/kegg/pathway.html ) , qtl data , and more . verygene ( http://www.verygene.com ) ( yang et al . 2011 ) links tissue - specific gene expression data to data on gene function ( go ) , reactome ( http://www.reactome.org ) , kegg pathways , mp annotations , disease associations , and targeting drugs . among the web tools for candidate gene identification 2011 ) , which adds mouse mp annotations , as well as mouse and human gene function ( go ) annotations , to genes in an identified qtl interval region to assist in predicting candidate genes . using the tools described above and elsewhere , a number of recent studies highlight the use of mouse mp annotations in the identification or validation of candidate gene sets in human disease and mouse studies : dickerson et al . ( 2011 ) identified 1,965 human disease genes from omim s morbid map and separated them according to whether the knockout phenotype of the mouse ortholog was lethal ( essential ) or viable from phenotype data coded to the mp in mgi . human genes in this set with mouse orthologs having a lethal phenotype are over - represented among disease genes associated with cancer and highly connected in protein ( 2012 ) discovered novel candidate genes for congenital diaphragmatic hernia by expression profiling of mouse embryonic diaphragm , then applying gene enrichment analysis on this identified set with mgi annotated data of muscle development and metabolism terms in the go and abnormal muscle and cardiovascular phenotype terms from the mp ontology . one candidate gene , pre - b - cell leukemia transcription factor one ( pbx1 ) , when mutated , results in a range of previously undetected diaphragmatic defects in mice.meehan et al . ( 2011 ) used mgi phenotype data associated with mp terms and mouse model data to create a set of similarly annotated genes / genotypes likely to have previously uncharacterized autistic - like phenotypes . the implicated genes considerably overlapped with a set of over 300 human genes associated with human autism spectrum disorder due to small , rare copy number variants ( cnvs , pinto et al . ( 2012 ) identified 12 mp ontology term annotations that are significantly enriched in genes overlapping inherited rare autism cnvs and are consistent with observable phenotypes associated with human autism spectrum disorder behaviors.shaikh et al . ( 2011 ) identified a group of genes enriched in human developmental delay - associated cnvs , which when disrupted in mice , result in specific nervous system phenotypes . the most significant term annotated to these genes was an abnormal nervous system white matter tract phenotype , which was used to narrow the candidate gene set for further analysis.bays et al . enrichment analysis revealed 77 mp terms , including cognitive and motor phenotypes associated with mutations in the mouse orthologs that revealed new candidate genes . a similar gene enrichment result was shown using the human phenotype ontology annotations derived from omim.hageman et al . ( 2011 ) used mp annotations to kidney phenotypes to narrow the genomic intervals and find candidate genes for qtl affecting the urinary albumin - to - creatinine ratio in mice . dickerson et al . ( 2011 ) identified 1,965 human disease genes from omim s morbid map and separated them according to whether the knockout phenotype of the mouse ortholog was lethal ( essential ) or viable from phenotype data coded to the mp in mgi . human genes in this set with mouse orthologs having a lethal phenotype are over - represented among disease genes associated with cancer and highly connected in protein protein interaction networks . ( 2012 ) discovered novel candidate genes for congenital diaphragmatic hernia by expression profiling of mouse embryonic diaphragm , then applying gene enrichment analysis on this identified set with mgi annotated data of muscle development and metabolism terms in the go and abnormal muscle and cardiovascular phenotype terms from the mp ontology . one candidate gene , pre - b - cell leukemia transcription factor one ( pbx1 ) , when mutated , results in a range of previously undetected diaphragmatic defects in mice . meehan et al . ( 2011 ) used mgi phenotype data associated with mp terms and mouse model data to create a set of similarly annotated genes / genotypes likely to have previously uncharacterized autistic - like phenotypes . the implicated genes considerably overlapped with a set of over 300 human genes associated with human autism spectrum disorder due to small , rare copy number variants ( cnvs , pinto et al . ( 2012 ) identified 12 mp ontology term annotations that are significantly enriched in genes overlapping inherited rare autism cnvs and are consistent with observable phenotypes associated with human autism spectrum disorder behaviors . ( 2011 ) identified a group of genes enriched in human developmental delay - associated cnvs , which when disrupted in mice , result in specific nervous system phenotypes . the most significant term annotated to these genes was an abnormal nervous system white matter tract phenotype , which was used to narrow the candidate gene set for further analysis . enrichment analysis revealed 77 mp terms , including cognitive and motor phenotypes associated with mutations in the mouse orthologs that revealed new candidate genes . a similar gene enrichment result was shown using the human phenotype ontology annotations derived from omim . ( 2011 ) used mp annotations to kidney phenotypes to narrow the genomic intervals and find candidate genes for qtl affecting the urinary albumin - to - creatinine ratio in mice . thus , the predictive value of mouse mutant phenotypes in identifying new candidate genes assists researchers in revealing the complex nature of human diseases . new terms and structural refinements are incorporated as required by phenotype annotation efforts at mgi and other databases , phenotyping centers , mutagenesis projects , investigator research , and review by biological domain experts . mgi curates information on published mouse mutations and electronically imports phenotype and disease model information from other sources . mgi continues to adapt as new data drive database infrastructure and as public data presentation changes . for example , changes are already underway to accommodate europhenome and the sanger institute s large - scale phenotype data derived from targeted knockout mutations , as well as future impc phenotype data . additional new sources of mouse allele , variant , and phenotype data will arise from the collaborative cross ( cc , http://csbio.unc.edu/ccstatus ) ( churchill et al 2004 ; threadgill and churchill 2012 ) and the diversity outcross ( do , http://cgd.jax.org/datasets/phenotype/svensondo.shtml ) ( svenson et al . 2012 ) , as well as mutations induced by engineered zinc finger nucleases ( osiak et al . 2011 ) . 2009 ; takeda et al . 2007 ; wang et al . 2008 ) , and the detection by nexgen and whole - exome sequencing of significant numbers of previously undetectable enu mutations ( cf . 2011 ; boles et al . 2009 ; guryev and cuppen 2009 ; sun et al . 2012 ) will further increase the genomic mutations and phenotypic data that require mp and nomenclature standards for integration with existing data . the promise of integrating these many streams of phenotype data with a robust mp ontology will enable a growing reservoir of standardized data for data mining , gene set enrichment studies , candidate disease model identification , and validation of computational predictions . many challenges remain in the ability to use computational tools to analyze and compare data from human clinical and mouse phenotype resources . human go data are freely available via the universal protein resource go annotations ( uniprot - goa , mp ontology http://www.ebi.ac.uk/goa ) ( dimmer et al . 2012 ) , but genetic , disease , and clinical data are scattered in many databases with differing formats and accessibility , and many resources are not maintained in a computational - friendly format ( kntzer et al . the hp , now being adopted by resources such as ncbi , is available for standardization of human clinical symptoms ( robinson et al . 2008 ) and is mapped to omim disease records . logical definitions derived for the hp are mapped to similar ontologies such as the mp ( mungall et al . the hp is only one part of the infrastructure needed for human disease data management , however . a comprehensive disease ontology with descriptions and definitions of disease terms in the context of observable clinical features , including a mapping to other phenotype ontologies such as hp and/or mp , is required to maximize the interoperability and computational access to the wide range of human disease data . current vocabularies for human disease have a number of drawbacks that prevent their wide adoption as a robust source for human disease annotation . omim , while an excellent source of text descriptions of disease , lacks a hierarchical structure and is limited to mendelian disease . the international classification of disease ( icd , http://www.nlm.nih.gov/mesh/mbrowser.html ) is designed for physician billing codes and thus is confounded by many nondisease terms such as those for injury and infection . the systematized nomenclature of medicine clinical terms ( snomed - ct , http://www.ihtsdo.org/snomed-ct ) must be licensed for use by country or affiliation and is thus not a publicly available resource . in addition , the medical subject headings ( mesh)-disease branch at the u.s . national library of medicine ( nelson et al . 2004 ) is increasingly incorporating omim disease terms . ultimately , the successful growth and maturation of one or more of these or other proposed disease ontologies and vocabularies should lead to greater interoperability of human genetic , disease , and clinical data among the scattered resources , as well as integration with model organism data . adoption of semantic and syntactic standards by the human clinical community will facilitate integration of data from a multitude of resources and allow the ability to compute over many data sets , as has been demonstrated for mouse genetic and phenotype data via the mp .

the mammalian phenotype ontology ( mp ) is a structured vocabulary for describing mammalian phenotypes and serves as a critical tool for efficient annotation and comprehensive retrieval of phenotype data . importantly , the ontology contains broad and specific terms , facilitating annotation of data from initial observations or screens and detailed data from subsequent experimental research . using the ontology structure , data are retrieved inclusively , i.e. , data annotated to chosen terms and to terms subordinate in the hierarchy . thus , searching for abnormal craniofacial morphology also returns annotations to megacephaly and microcephaly , more specific terms in the hierarchy path . the development and refinement of the mp is ongoing , with new terms and modifications to its organization undergoing continuous assessment as users and expert reviewers propose expansions and revisions . a wealth of phenotype data on mouse mutations and variants annotated to the mp already exists in the mouse genome informatics database . these data , along with data curated to the mp by many mouse mutagenesis programs and mouse repositories , provide a platform for comparative analyses and correlative discoveries . the mp provides a standard underpinning to mouse phenotype descriptions for existing and future experimental and large - scale phenotyping projects . in this review we describe the mp as it presently exists , its application to phenotype annotations , the relationship of the mp to other ontologies , and the integration of the mp within large - scale phenotyping projects . finally we discuss future application of the mp in providing standard descriptors of the phenotype pipeline test results from the international mouse phenotype consortium projects .

chaos is one of the essential concepts to justify a statistical treatment of deterministic dynamical systems . in a chaotic system a small initial error diverges exponentially , as characterized quantitatively by the lyapunov exponents @xmath0 , and it means that it is impossible in principle to predict precisely any quantity of deterministic systems at any time and a statistical treatment of the systems is required . it is well known that even one - particle systems can be chaotic and have some of the important statistical properties of equilibrium statistical mechanics such as the mixing property , etc . for this reason many works on the subject of chaos have been done in one - particle systems , for example , billiard systems and lorentz gas models @xcite . however many - particle effects should still play an important role in some statistical aspects , such as the central limit theorem and a justification of thermodynamical reservoirs , etc . therefore it should be interesting to know what happens with the combination of a chaotic effect and a many - particle effect , in other words , to know which chaotic effects do not appear in one - particle systems . the lyapunov spectrum is introduced as the sorted set @xmath1 of lyapunov exponents satisfying the condition @xmath2 , and is a quantity to characterize the many - particle chaotic dynamics . recently a stepwise structure of the lyapunov spectrum was reported numerically , as one of the many - particle chaotic effects , in many - disk systems in which each disk interacts with the other disks by hard - core interactions @xcite . this stepwise structure appears in the region of small absolute values of lyapunov exponents . this fact suggests that steps in the lyapunov spectra come from slow and macroscopic behavior of the system , because small positive lyapunov exponents should correspond to slow relaxation precesses . this point is partly supported by the existence of a global structure in the lyapunov vectors , the so called lyapunov modes , which are wavelike structures in the tangent space of each eigenvector of a degenerate lyapunov exponent , that is , for each stepwise structure @xcite . the wavelike structure of the lyapunov vectors appears as a function of the particle position , so this structure is also important as a relation to connect the tangent space with the phase space . although the lyapunov vectors have been the subject of some works more than a decade ago ( for example , see refs . @xcite ) , it is remarkable that an observation of their global structure in fully chaotic many - particle systems has only recently appeared . explanations for the stepwise structure of the lyapunov spectra have been attempted using periodic orbit models @xcite and using the master equation approach @xcite . other approaches to the lyapunov modes have included using a random matrix approach for a one - dimensional model @xcite and using a kinetic theoretical approach @xcite , by considering these as the `` goldstone modes '' @xcite . if the stepwise structure of lyapunov spectra is a reflection of a global behavior of the system , then one may ask the question : does such a structure depend on boundary conditions which specify the global structure of the system ? one of the purposes of this paper is to answer this question using some simple examples . in this paper we investigate numerically the stepwise structure of the lyapunov spectra in many - hard - disk systems of two - dimensional rectangular shape with the four kinds of the boundary conditions : [ _ a1 _ ] purely periodic boundary conditions , [ _ a2 _ ] periodic boundary conditions in the @xmath3-direction and hard - wall boundary conditions in the @xmath4-direction , [ _ a3 _ ] hard - wall boundary conditions in the @xmath3-direction and periodic boundary conditions in the @xmath4-direction , and [ _ a4 _ ] purely hard - wall boundary conditions . in all cases we took the @xmath4-direction as the narrow direction of the rectangular shape of the system and @xmath3-direction as the longer orthogonal direction . the case [ _ a1 _ ] means that the global shape of the system is like the surface of a doughnut shape , the cases [ _ a2 _ ] and [ _ a3 _ ] means that the system has the shape of the surface of pipe with hard - walls in its ends . case [ _ a2 _ ] is a long pipe with small diameter while case [ _ a3 _ ] is a short pipe with a large diameter . the case [ _ a4 _ ] means that the system has just a rectangular shape surrounded by hard - walls . adopting hard - wall boundary conditions in a particular direction destroys the total momentum conservation in that direction , so by considering these models we can investigate the effects of the total momentum conservation on the stepwise structure of the lyapunov spectra and the lyapunov modes . this can be used to check some theoretical approaches to these phenomena like those in refs . @xcite , in which the total momentum conservation plays an essential role in explaining the stepwise structure of the lyapunov spectra or the lyapunov modes . we obtain different stepwise structures of the lyapunov spectra with each different boundary condition case . especially , we observe a stepwise structure of the lyapunov spectrum even in the purely hard - wall boundary case [ _ a4 _ ] , in which the total momentum is not conserved in any direction . the second purpose of this paper is to categorize the stepwise structure of the lyapunov spectra according to the wavelike structure of the lyapunov vectors . so far wavelike structure of the lyapunov vectors was reported in the lyapunov vector components as a function of positions , for example in the quantity @xmath5 as a function of the position @xmath6 ( the transverse lyapunov mode ) @xcite and in the quantity @xmath7 as a function of the position @xmath6 ( the longitudinal lyapunov mode ) @xcite , in which @xmath5 ( @xmath7 ) is the @xmath4-component ( @xmath3-component ) of the spatial coordinate part of the lyapunov vector of the @xmath8-th particle corresponding to the @xmath9-th lyapunov exponent @xmath0 , and @xmath6 is the @xmath3-component of the spatial component of the @xmath8-th particle . these wavelike structures appear in the stepwise region of the lyapunov spectrum . however it is not clear whether there is a direct connection between the sequence and the kinds of steps of the lyapunov spectrum and the modes of wavelike structure of the lyapunov vectors in the numerical studies , that is , how we can categorize the steps of the lyapunov spectrum by the lyapunov modes . in this paper we show another type of wavelike structure of the lyapunov vectors , which appears in the quantity @xmath10 with the @xmath4-component @xmath11 of the momentum coordinate of the @xmath8-th particle , and use this wavelike structure to categorize the stepwise structure of the lyapunov spectra . the lyapunov vector components @xmath7 , @xmath5 and @xmath10 have a common feature in which each quantity gives a constant corresponding to one of the zero lyapunov exponents of the system with purely periodic boundary conditions , because of the conservation of center of mass or the deterministic nature of the orbit . more concretely in this paper we consider the two kinds of graphs : [ _ b1 _ ] the quantity @xmath5 as a function of the position @xmath6 , namely the transverse lyapunov mode , and [ _ b2 _ ] the quantity @xmath10 as a function of the position @xmath6 and time ( or collision number ) . in the two - dimensional rectangular systems consisting of many - hard - disks with periodic boundary conditions ( the boundary case [ _ a1 _ ] ) it is known that there are two types of steps of the lyapunov spectra : steps consisting of two lyapunov exponents and steps consisting of four lyapunov exponents @xcite . the wavelike structure in the graph [ _ b1 _ ] corresponding to the two - point steps of the lyapunov spectrum for such a rectangular system is well known . in this paper we show the wavelike structure corresponding to the four - point steps of the lyapunov spectrum in the graph [ _ b2 _ ] . besides , we observe time - dependent oscillations in the graph [ _ b2 _ ] , whereas the graph [ _ b1 _ ] is rather stationary in time . the wavelike structure in the graph [ _ b2 _ ] also appears in the rectangular systems with a hard - wall boundary condition ( the boundary cases [ _ a2 _ ] , [ _ a3 _ ] and [ _ a4 _ ] ) , specifically even in the case of purely hard - wall boundary conditions in which the transverse lyapunov mode [ _ b1 _ ] does not appear . we show that the stepwise structure of the lyapunov spectra in the boundary cases [ _ a1 _ ] , [ _ a2 _ ] , [ _ a3 _ ] and [ _ a4 _ ] can be categorized by the wavelike structures of the graphs [ _ b1 _ ] and [ _ b2 _ ] . one of the problems which make it difficult to investigate the structure of the lyapunov spectra and the lyapunov modes is that the calculation of a full lyapunov spectra for many - particle system is a very time - consuming numerical calculation . therefore it should be important to know how we can calculate the stepwise structure of the lyapunov spectra and the lyapunov modes with as little calculation time as possible . it is known that a rectangular system has a wider stepwise region of the lyapunov spectrum than a square system @xcite . noting this point , in this paper we concentrate on the most strongly rectangular system , namely on the quasi - one - dimensional system in which the rectangle is too narrow to allow particles to exchange their positions . as will be shown in this paper , the stepwise structure of the lyapunov spectrum for the quasi - one - dimensional system is the same as the fully rectangular system which allows exchange of particle positions and each particle can collide with any other particle , and the steps of the lyapunov spectra consist of two - point steps and four - point steps in the periodic boundary case [ _ a1 _ ] . we also determine an appropriate particle density to give clearest stepwise structure of the lyapunov spectrum in the quasi - one - dimensional system . the outline of this paper is as follows . in sect . [ quasionedime ] we discuss how we can get the stepwise structure of the lyapunov spectra for a small number of particle systems with a quasi - one - dimensional shape . the density dependence of the lyapunov spectrum for the quasi - one - dimensional system is investigated to get a clearly visible stepwise structure of the lyapunov spectra . in sect . [ periopp ] we consider the purely periodic boundary case ( the boundary case [ _ a1 _ ] ) , and investigate wavelike structures in the graphs [ _ b1 _ ] and [ _ b2 _ ] of lyapunov vector components . in sect . [ pppwwpww ] we consider the cases including a hard - wall boundary condition ( the boundary cases [ _ a2 _ ] , [ _ a3 _ ] and [ _ a4 _ ] ) with calculations of the graphs [ _ b1 _ ] and [ _ b2 _ ] , and compare the stepwise structures of the lyapunov spectra and the wavelike structures in the graphs [ _ b1 _ ] and [ _ b2 _ ] in the above four boundary cases . finally we give our conclusion and remarks in sect . [ concl ] . the stepwise structure of the lyapunov spectra is purely a many - particle effect of the chaotic dynamics , and so far it has been investigated in systems of 100 or more particles . however the numerical calculation of lyapunov spectra for such large systems is not so easy even at present . noting this point , in this section we discuss briefly how we can investigate the stepwise structure of the lyapunov spectrum for a system whose number of particles is as small as possible . we also discuss what is a proper particle density to get clear steps of the lyapunov spectrum . these discussions give reasons to choose some values of system parameters used in the following sections . and @xmath12 . ] [ qua1dim ] we consider two - dimensional systems consisting of @xmath13 number of hard - disks in which the radius of the particle is @xmath14 and the width ( height ) of the system is @xmath15 ( @xmath16 ) . one way to get the stepwise structure of lyapunov spectrum in a two - dimensional system consisting of a small number of particles is to choose a rectangular system rather than a square system , because the stepwise region in the lyapunov spectrum is wider in a more rectangular system rather than in a square system even if the number of particles is the same @xcite . noting this characteristic , we concentrate on the most rectangular case , namely the quasi - one - dimensional system defined by the conditions @xmath17 a schematic illustration of the quasi - one - dimensional system is shown in fig . [ qua1dim ] . in other words , the quasi - one - dimensional system is introduced as a narrow rectangular system where each particle can interact with two nearest - neighbor particles only and particles do not exchange the order of their positions . in the quasi - one - dimensional system the upper bound @xmath18 of the particle density @xmath19 is given by @xmath20 . in such a system we can get a stepwise structure of the lyapunov spectrum even in a 10-particle system ( @xmath21 ) , as shown in fig . [ 10lya ] , which is the lyapunov spectrum normalized by the maximum lyapunov exponent @xmath22 . to get this figure we chose the parameters as @xmath23 , @xmath24 , @xmath25 , and the mass @xmath26 of the particle and the total energy @xmath27 are given by @xmath28 and @xmath13 , respectively , and we used periodic boundary conditions in both the directions . the particle density of this system is given by @xmath29 . noting the pairing property of the lyapunov spectrum for hamiltonian systems , namely the property that in hamiltonian systems any positive lyapunov exponent accompanies a negative lyapunov exponent with the same absolute value @xcite , we plotted the first half of the lyapunov spectrum in fig . [ 10lya ] . ( the same omission of the negative branch of lyapunov spectra from plots will be used throughout this paper . ) it is clear that the lyapunov exponents @xmath30 and @xmath31 form a two - point step in this lyapunov spectrum . and @xmath31 shown as the black circles form a two - point step accompanying the transverse lyapunov modes shown in fig . [ 10mod ] . the gray circle is the zero - lyapunov exponent @xmath32 whose corresponding lyapunov vector components @xmath5 show a constant behavior ( also see fig . [ 10mod ] ) . ] [ 10lya ] in order to calculate lyapunov spectra and lyapunov vectors we use the algorithm due to benettin et al . , which is characterized by intermittent rescaling and renormalization of lyapunov vectors @xcite . in the application of this algorithm to systems with hard - core particle interactions , we calculate the matrix @xmath33 , whose column vectors give the lyapunov vectors @xmath34 corresponding to the local - time lyapunov exponent @xmath35 at time @xmath36 just after the @xmath37-th collision of particles . the dynamics of the matrix @xmath33 is given by @xmath38 , in which @xmath39 is the matrix required to normalize each column vector of the operated matrix , @xmath40 is the gram - schmidt procedure ensuring the orthogonality of the columns of the operated matrix , and @xmath41 specifies the tangent space dynamics including a free flight and a particle collision @xcite . the local - time lyapunov exponent @xmath35 is calculated as the exponents of the exponential divergence ( contraction ) from the @xmath9-th column vectors of the matrix @xmath33 to the @xmath9-th column vectors of the matrix @xmath42 . the lyapunov exponent @xmath0 is given as a time - averaged local - time lyapunov exponent after a long time calculation : @xmath43 . here we use the standard metric @xmath44 $ ] for the tangent space with the @xmath3-component @xmath45 and @xmath4-component @xmath46 of the lyapunov vector of the @xmath8-th particle corresponding to the local - time lyapunov exponent @xmath47 . other articles such as refs . @xcite should be referred to for more details of the benettin algorithm and the tangent space dynamics of many - hard - disk systems . it is very important to note that there are two ways that convince us of the structure of the lyapunov spectrum ; one is simply to find a step structure directly in the lyapunov spectrum , and another is to find a structure in the lyapunov vectors corresponding to specific lyapunov exponents . [ 10mod ] is the plot of the time - average @xmath48 of the @xmath4-component of the @xmath8-th particle of the spatial part of the lyapunov vector @xmath49 corresponding to the lyapunov exponents @xmath0 , for @xmath50 and @xmath51 as functions of the time - average @xmath52 of the normalized @xmath3-component of spatial coordinate of the @xmath8-th particle ( @xmath53 ) ( the graph [ _ b1 _ ] ) . the corresponding lyapunov exponents @xmath31 and @xmath30 are shown as the black - filled circles in fig . [ 10lya ] and construct a two - point step of the lyapunov spectrum . to take the time average of the quantities @xmath5 and @xmath6 we picked up these values just after particle collisions over @xmath54 collisions and take the arithmetic averages of them . the step consisting of two points in the lyapunov spectrum of fig . [ 10lya ] accompanies wavelike structures in their lyapunov vectors , which are called the transverse lyapunov modes . it should be emphasized that the lyapunov modes in fig . [ 10mod ] are rather stationary over @xmath54 particle collisions and to take the time average can be a useful way to get clear their wavelike structures . in this figure we fitted the numerical data for the lyapunov modes corresponding to the lyapunov exponents @xmath0 , @xmath55 and @xmath51 , to the function @xmath56 ( @xmath57 for the triangle dots , and @xmath58 for the square dots ) . it should be noted that the difference @xmath59 of the two values of the phases @xmath60 is approximately @xmath61 , meaning that these two waves are orthogonal with each other . the graph of the lyapunov vector component @xmath5 as a function of the position @xmath6 ( @xmath53 ) become constant in one of the zero lyapunov exponent @xmath32 shown as the gray - filled circle in fig . [ 10lya ] . in fig . [ 10mod ] we also fitted the numerical data corresponding to the zero - lyapunov exponent @xmath32 by the constant function @xmath62 with the fitting parameter value @xmath63 . [ 10mod ] although we can recognize the two - point step of the lyapunov spectrum in fig . [ 10lya ] , it is important to note that there is another type of steps in the two - dimensional hard - disk system with a rectangular shape and periodic boundary conditions . it is well known that in such a system the lyapunov spectrum can have a stepwise structure consisting of two - point steps and four - point steps @xcite . if we want to investigate the four - point steps of the lyapunov spectrum we may have to consider a system consisting of more than 10 particles . now we mention an angle in components of the lyapunov vectors . [ 10angdqdp ] is the graph for the time - average @xmath64 of the angle @xmath65 between the spatial part @xmath66 and the momentum part @xmath67 of the lyapunov vector @xmath68 where @xmath69 is the transverse operation , and @xmath65 is defined by @xmath70 except for the ones corresponding to the zero lyapunov exponents . here in order to take the time - average of the angle @xmath65 we picked up its values just after particle collisions over @xmath71 collisions and took the arithmetic average of them . this graph shows that the spatial part @xmath66 and the momentum part @xmath67 of the lyapunov vector are pointed toward almost the same direction , especially for the lyapunov vectors corresponding to small absolute values of lyapunov exponents @xcite . this fact suggests that if we get a structure in the vector @xmath66 then we may get the similar structure in the vector @xmath67 , and vice versa . it should also be noted that this gives a justification for some approaches to lyapunov exponents in which the lyapunov exponents are calculated through the spatial coordinate part only ( or the momentum part only ) of the lyapunov vector @xcite . we may also note that the graph for @xmath65 , @xmath72 and @xmath73 , @xmath72 are symmetric with respect to the line @xmath74 , which comes from the symplectic property of the hamiltonian dynamics . [ 10angdqdp ] another important point to get a clear stepwise structure for the lyapunov spectrum in a small system is to choose a proper particle density of the system . even if we restrict our consideration to quasi - one - dimensional systems , the shape of the lyapunov spectrum depends on the particle density , so we should choose a density that gives a clearly visible stepwise structure in the lyapunov spectrum . [ pplya50d](a ) is the lyapunov spectra normalized by the maximum lyapunov exponents for quasi - one - dimensional systems consisting of 50 hard - disks ( @xmath75 ) with periodic boundary conditions in both directions . we also give an enlarged figure [ pplya50d](b ) for the small lyapunov exponent region . here the system parameters are given by @xmath23 , @xmath76 , @xmath77 , and we used the case of @xmath78 and @xmath79 . the five lyapunov spectra correspond to the case of @xmath80 ( the circle dots , the density @xmath81 ) , the case of @xmath82 ( the triangle dots , the density @xmath83 ) , the case of @xmath84 ( the square dots , the density @xmath85 ) , the case of @xmath86 ( the diamond dots , the density @xmath87 ) , the case of @xmath88 ( the upside - down triangle dots , the density @xmath89 ) . the maximum lyapunov exponents @xmath90 are given approximately by @xmath91 , @xmath92 , @xmath93 , @xmath94 and @xmath95 in the cases of @xmath96 and @xmath97 , respectively . as shown in figs . [ pplya50d](a ) and ( b ) , for smaller values of the quantity @xmath98 ( namely in the higher particle density ) the gaps between the nearest steps of the lyapunov spectrum become larger , although the stepwise region of the lyapunov spectrum does not seem to depend on the quantity @xmath98 . this means that we can get a clear stepwise structure of the lyapunov spectrum in the small @xmath98 case ( namely at high density ) . [ pplya50d ] in fig . [ pplya50d](b ) the lyapunov exponents accompanying wavelike structures ( constant behaviors ) in the time - averaged lyapunov vector components @xmath99 , as functions of the position @xmath100 , are shown as the dots blacked ( grayed ) out . in the small @xmath98 case , looking from the zero lyapunov exponents , the two - point step appears first ( see the cases of @xmath101 and @xmath28 in fig . [ pplya50d](b ) ) , whereas the four - point step appears first in the large @xmath98 case ( see the cases of @xmath102 and @xmath88 in fig . [ pplya50d](b ) ) . besides , at least in the small @xmath98 case , the two - point steps and the four - point steps do not appear repeatedly ( see the cases of @xmath80 and @xmath103 in fig . [ pplya50d](b ) ) . these facts mean that the sequence of steps in the lyapunov spectrum depends on the quantity @xmath98 , namely the particle density . wavelike structures in the time - averaged lyapunov vector components @xmath48 as functions of the position @xmath104 , namely the transverse lyapunov modes , appear mainly in two - point steps of the lyapunov spectra . therefore we can use these wavelike structures to distinguish two - point steps from four - point steps of the lyapunov spectra . however such a distinguishability sometimes seems to fail in steps of the lyapunov spectra near a region where the lyapunov spectra is changing smoothly . actually the transverse lyapunov modes may appear even in some four - point steps , if they are near such a smoothly changing lyapunov spectrum region . on the other hand , in such a region of the lyapunov spectra , fluctuation of lyapunov vectors is rather large , and the wavelike structure of the lyapunov vectors become vague . in fig . [ pplya50d](b ) we did not indicate by black - filled dots the lyapunov exponents whose corresponding lyapunov vector components @xmath48 as functions of the position @xmath104 show wavelike - structures with such a level of vagueness . based on the discussions in this section , in the following two sections we consider only the case whose system parameters are given by @xmath105 , @xmath23 , @xmath78 and @xmath79 . the height and the width of the system are given by @xmath76 and @xmath106 ( the density @xmath107 ) in the purely periodic boundary case considered in the next section . in this case , as will be shown in the next section , we can recognize at least 2 clear four - point steps , and the two - point steps and the four - point steps of the lyapunov spectrum appear repeatedly in the first few steps in the lyapunov spectrum for the system with the purely periodic boundary conditions . we always take the time averaged quantities @xmath99 and @xmath100 of the quantities @xmath5 and @xmath6 , respectively as the arithmetic average of their values taken in the times immediately after particle collisions , over @xmath54 collisions . we calculated more than @xmath108 collisions ( @xmath109 collisions in some of the models ) in order to get the lyapunov spectra and the lyapunov vectors in the models considered in this paper . in this section we consider the lyapunov spectrum for the quasi - one - dimensional system with periodic boundary conditions in both the directions ( the boundary case [ _ a1 _ ] ) . a schematic illustration of this system for latter comparisons is given in fig . [ pp ] in which the broken line of the boundary means to take the periodic boundary conditions . this system satisfies total momentum conservation in both the directions , and is regarded as a reference model for the models considered in the following section . [ pp ] fig . [ pplya ] is the small positive lyapunov exponent region of the lyapunov spectrum normalized by the maximum lyapunov exponent @xmath110 , including its stepwise region , for a quasi - one - dimensional system with periodic boundary conditions in both the directions . the global shape of the lyapunov spectrum is given in the inset in this figure . we used the values of the system parameters chosen at the end of the preceding section . at least 5 steps consisting 3 two - point steps and 2 four - point steps are clearly visible in this lyapunov spectrum . [ pplya ] the two - point steps of the lyapunov spectrum accompany wavelike structures in their corresponding lyapunov vectors . [ ppdqy ] is the graphs of the time - averaged lyapunov vector components @xmath48 corresponding to the lyapunov exponent @xmath0 , @xmath111 and @xmath112 as functions of the time - averaged position component @xmath104 normalized by the length @xmath15 ( the graph [ _ b1 _ ] ) . the lyapunov exponents used for this figure are shown as the black or gray circles in fig . [ pplya ] . in this figure we also gave fittings of the numerical data by sinusoidal equations and a constant function . the fitting equations are @xmath113 for @xmath114 ( @xmath115 ) , and @xmath116 for @xmath117 ( @xmath118 ) . concerning these fitting parameters , it is important to note the relations @xmath119 , @xmath120 , @xmath121 and @xmath122 , meaning that the two wavelike structures in the same two - point step are orthogonal to each other . in fig . [ ppdqy ] we also draw a graph of the averaged lyapunov vector component @xmath48 as a function of the normalized position @xmath52 corresponding to the second zero lyapunov exponent @xmath123 , which is roughly speaking constant , and is fitted by a constant function @xmath124 with the fitting parameter value @xmath125 . these results suggest a conjecture for the approximate form of the lyapunov vector component @xmath126 corresponding to the lyapunov exponents @xmath127 and @xmath128 in the same @xmath37-th two - point step counting from the zero lyapunov exponents as @xmath129 @xmath53 with constants @xmath130 and @xmath131 . ( note that in this paper we always count the sequence of steps of lyapunov spectra looking from the zero lyapunov exponents , so , for example , the two - point step consisting of the lyapunov exponents @xmath132 and @xmath133 ( @xmath134 and @xmath135 ) in the lyapunov spectrum shown in fig . [ ppdqy ] is the first ( second ) two - point step . ) it may be noted that the constant @xmath130 in eq . ( [ lyapuwave ] ) should be determined by the normalization condition of the lyapunov vector , which is used in the benettin algorithm to calculate the lyapunov spectrum and lyapunov vectors in this paper . [ ppdqy ] it should be emphasized that the wavelike structures in figs . [ 10mod ] and [ ppdqy ] correspond to the two - point steps of the lyapunov spectrum . we can not recognize such a clear wavelike structure in the graph of the lyapunov vector component @xmath48 as a function of the position @xmath104 corresponding to the four - point steps of the lyapunov spectrum . this suggests that the physical meaning of the four - point steps is different from the two - point steps , and we should consider a different quantity to investigate as a structure of lyapunov vectors corresponding to the four - point steps of the lyapunov spectrum . now , as one of the important results of this paper , we show that wavelike structures in the quantities @xmath10 as functions of @xmath6 and the collision number appear in the four - point steps of the lyapunov spectrum . as a motivation to introduce the quantity @xmath10 to investigate its structure , we note that the small perturbation of the spatial coordinates of the particles in the direction of the orbit , namely the small perturbation @xmath136 , leads to a zero - lyapunov exponent , so that the quantities @xmath10 , @xmath53 should give a constant value corresponding to this zero lyapunov exponent . this is the common feature as the quantity @xmath5 , which shows a constant behavior corresponding to one of the zero - lyapunov exponents owing to the conservation of center of mass , and whose wavelike structure we have already discussed . before showing graphs of the quantities @xmath10 , we discuss some difficulties in the investigation of wavelike structure in these quantities . it is much harder to get the wavelike structure of these quantities corresponding to the four - point steps of the lyapunov spectrum compared to the quantities @xmath5 corresponding to the two - point steps of the lyapunov spectrum , for at least two reasons . as the first reason , fluctuation in the wavelike structure of the quantities @xmath10 is much bigger than in the wavelike structure of the quantities @xmath5 , partly because such a fluctuation is magnified in the case of a small absolute value of the quantity @xmath11 appearing in the denominator of the quantity @xmath10 . secondly , the wavelike structure of the quantity @xmath10 , at least the magnitude of its wave , oscillates periodically in time , whereas the wavelike structure of the quantities @xmath5 in fig . [ ppdqy ] are stationary at least over more than @xmath54 collisions . this fact gives an upper bound on the time period ( or the collision number interval ) over which we can take the time - average of the quantities @xmath10 in order to suppress the fluctuations and get their clear wavelike structures . in this paper we express the local time - averages of the quantities @xmath137 and @xmath6 as @xmath138 and @xmath139 , respectively , with the suffix @xmath140 to remind us that they can change in time . [ ppdqypy ] [ ppdqypycont ] in this and the next sections we will give the many graphs of @xmath10 as functions of @xmath6 and the collision number by taking their local time - averages , so here we summarize how we calculate the data for those graphs from a technical point of view . first we take the arithmetic time - average @xmath138 and @xmath139 of the quantities @xmath10 and @xmath6 , respectively , using their values just after particle collisions over @xmath141 collisions ( @xmath142 collisions ) , but if the absolute value @xmath143 of the momentum is less than 10 percent ( 5 percent ) of the averaged momentum amplitudes @xmath144 then we exclude the quantity @xmath10 at that time from samples to take this local time - average , in the models of this section and the subsection [ harwalpw ] ( in the models of the subsections [ harwalwp ] and [ harwalww ] ) . ( therefore the sample number for taking the arithmetic averages can be less than @xmath141 ( @xmath142 ) in the models of this section and the subsection [ harwalpw ] ( in the models of the subsections [ harwalwp ] and [ harwalww ] ) . ) on this local time - averages we can still get more than ten locally time - averaged datas for different times in one period of the time - oscillations for the graphs in the slowest time - oscillating movement of the quantity @xmath10 corresponding to a step of the lyapunov spectra , for example , corresponding to the first four - point step of the model in this section . in this paper we consider the graph of the quantity @xmath138 as a function of @xmath139 and @xmath145 which is the first collision number of the collision number interval taking the local time averages @xmath146 . figure [ ppdqypy](a ) and ( b ) is the graphs of the quantity @xmath138 as functions of the normalized position @xmath147 and the collision number @xmath145 ( the graph [ _ b2 _ ] ) , corresponding to the lyapunov exponents @xmath0 , @xmath148 and @xmath149 , respectively , indicated by arrows in fig . [ pplya ] . these two graphs correspond to lyapunov exponents in different four - point steps and are given in the same collision number interval @xmath150 $ ] . in the graph corresponding to the lyapunov exponent @xmath151 ( @xmath152 ) we can recognize a spatial wavelike structure with the spatial wavelength @xmath28 ( @xmath153 ) oscillating in time . the time - oscillating period corresponding to the lyapunov exponent @xmath152 is about half of the period of the oscillation corresponding to the lyapunov exponent @xmath151 . these graphs , especially fig . [ ppdqypy](b ) , are the most difficult graphs to recognize the structures from their three - dimensional plots in this paper , and in order to recognize the structures the contour plots given in the bottoms of these three - dimensional plots may be helpful . in these contour plots we color - coded mountain regions ( @xmath154 ) and valley regions ( @xmath154 ) of the time - oscillating wavelike structure of the quantities @xmath138 by the red dotted contour lines of @xmath155 and the blue broken contour lines of @xmath156 , respectively , separating them by the black solid contour lines of @xmath157 . now we consider a relation among the quantities @xmath138 corresponding to lyapunov exponents in the same four - point step . fig . [ ppdqypycont ] is the contour plots of the quantity @xmath158 as functions of the normalized position @xmath147 and the collision number @xmath145 corresponding to the first four - point step consisting of the lyapunov exponents @xmath0 , @xmath159 and @xmath160 in the same collision number interval @xmath161 $ ] . here red dotted lines , black solid lines and blue broken lines correspond to @xmath162 and @xmath163 , respectively . it is clear that in these four graphs their spatial wavelengths ( given by the system length @xmath15 ) and time - oscillating periods ( given by a constant @xmath164 ) are almost the same as each other . on the other hand we can recognize that the position of the nodes of the spatial waves of the graphs [ ppdqypycont](a ) and [ ppdqypycont](b ) , as well as the nodes of the spatial waves of the graphs [ ppdqypycont](c ) and [ ppdqypycont](d ) , coincide with each other approximately , and the phase difference between the spatial waves of the graphs [ ppdqypycont](a ) and [ ppdqypycont](c ) is @xmath165 approximately . besides , the node of the time - oscillation of the wave - amplitude of the graphs [ ppdqypycont](a ) and [ ppdqypycont](c ) , as well as the nodes of the time - oscillation of the wave - amplitude of the graphs [ ppdqypycont](b ) and [ ppdqypycont](d ) , coincide with each other approximately , and the phase difference between time - oscillations of the graphs [ ppdqypycont](a ) [ ppdqypycont](b ) is about @xmath165 . these points are summarized in fig . [ phasecont1 ] , which is the schematic illustration of the phase relations among the time - oscillating wavelike structures of the quantity @xmath158 , here the phase [ _ p1 _ ] , [ _ p2 _ ] , [ _ p3 _ ] and [ _ p4 _ ] correspond to figs . [ ppdqypycont](a ) , ( b ) , ( c ) and ( d ) , respectively . these observations suggest that the lyapunov vector components @xmath166 , @xmath167 , @xmath168 and @xmath169 corresponding to the lyapunov exponents constructing the @xmath37-th four - point step are approximately expressed as @xmath170 @xmath53 , with constants @xmath171 , @xmath172 and @xmath173 . here @xmath164 is the period of the time - oscillation of the quantity @xmath174 in the first four - point step . ( in this paper we use the quantity @xmath164 as the period of the particle - particle collision number , but we can always convert it into the real time interval approximately by multiplying it with the mean free time , which is , for example , about @xmath175 in the model of this section . ) it may be emphasized that the level of approximation in eq . ( [ lyapuoscil ] ) for the four - point steps may be worse than in eq . ( [ lyapuwave ] ) for the two - point steps . as functions of the position @xmath176 and the collision number @xmath145 , corresponding to the first four - point step in the same collision number interval . the spatial wavelength and the period of the time - oscillations are given by @xmath15 and @xmath164 , respectively . thick gray lines means node lines , the region indicated by a red plus sign ( @xmath177 ) is the region where the quantity @xmath158 is positive , and the region indicated by a blue minus sign ( @xmath178 ) is the region where the quantity @xmath158 is negative . the phases [ _ p3 _ ] and [ _ p4 _ ] differ from the phases [ _ p1 _ ] and [ _ p2 _ ] by a phase shift of @xmath165 in the spatial direction . the phases [ _ p1 _ ] and [ _ p3 _ ] differ from the phases [ _ p2 _ ] and [ _ p4 _ ] by a phase shift of @xmath165 in time . ] [ phasecont1 ] in this section we consider quasi - one - dimensional systems with boundary conditions including a hard - wall boundary condition . noting that there are two directions in which we have to introduce the boundary conditions , we consider the three cases of systems ; [ _ a2 _ ] the case of periodic boundary conditions in the @xmath3-direction and hard - wall boundary conditions in the @xmath4-direction , [ _ a3 _ ] the case of hard - wall boundary conditions in the @xmath3-direction and periodic boundary conditions in the @xmath4-direction , and [ _ a4 _ ] the case of hard - wall boundary conditions in both the directions . to adopt the hard - wall boundary condition means that there is no momentum conservation in the direction connected by hard - walls , so it allows us to discuss the role of momentum conservation in the stepwise structure of the lyapunov spectrum by comparing models having a hard - wall boundary conditions with models having periodic boundary conditions . we will get different stepwise structures for the lyapunov spectra in the above three cases and the case of the preceding section , and the investigation of lyapunov vectors corresponding to steps of the lyapunov spectra leads to relating and to categorizing them with each other . in the systems with a hard - wall boundary condition we should carefully choose the width @xmath15 and the height @xmath16 of the systems for meaningful comparisons between the results in the systems with different boundary conditions . it should be noted that in systems with pure periodic boundary conditions , the centers of particles can reach to the periodic boundaries , while in hard - wall boundary conditions the centers of particles can only reach within a distance @xmath14 ( the particle radius ) of the hard - wall boundaries . in this sense the effective region for particles to move in the system with hard - wall boundary conditions is smaller than in the corresponding system with periodic boundary conditions , if we choose the same lengths @xmath15 and @xmath16 . in this section the lengths @xmath15 and @xmath16 of the systems with a hard - wall boundary condition are chosen so that the effective region for particle to move is the same as in the pure periodic boundary case considered in the previous section , and are given by @xmath179 in the case [ _ a2 _ ] , @xmath180 in the case [ _ a3 _ ] and @xmath181 in the case [ _ a4 _ ] . these choices of the lengths @xmath15 and @xmath16 also lead to the almost same mean free time in the four different boundary condition cases . in the cases of [ _ a2 _ ] and [ _ a4 _ ] with this choice of the system width @xmath16 , in principle there is a space to exchange the particle positions in the @xmath3-direction ( namely , strictly speaking these cases do not satisfy the second condition of eq . ( [ qua1dimcon ] ) ) , but the space is extremely narrow ( that is @xmath182 ) so that it is almost impossible for particle positions to actually be exchanged . the first case is the quasi - one - dimensional system with periodic boundary conditions in the @xmath3-direction and with hard - wall boundary conditions in the @xmath4-direction ( the boundary case [ _ a2 _ ] ) . a schematic illustration of this system is given in fig . [ pw ] in which periodic boundary conditions and hard - wall boundary conditions are represented as bold solid lines and broken lines , respectively . -direction and hard - wall boundary conditions in the @xmath4-direction . the broken line on the boundary means to take periodic boundary conditions , and the solid line on the boundary means to take hard - wall boundary conditions . ] [ pw ] [ pwlya ] figure [ pwlya ] is the lyapunov spectrum normalized by the maximum lyapunov exponent @xmath183 for this system . in this figure we showed a small positive region of the lyapunov spectrum including its stepwise structures , while the full scale of the positive branch of the lyapunov spectrum is shown in the inset . in this system the @xmath4-component of the total momentum is not conserved because of the hard - wall boundary conditions in the @xmath4-direction , so there are only 4 zero - lyapunov exponents in this system . this figure shows clearly that the steps of the lyapunov spectrum consist of four - point steps only , and there is no two - point step in the lyapunov spectrum which appears in the model discussed in the previous section . besides , we can not recognize a wavelike structure in the graph of lyapunov vector components @xmath184 as a function of the position @xmath100 ( the graph [ _ b1 _ ] ) in this model . a comparison of this fact with results in the previous model suggests that the two - point step of the lyapunov spectrum in the previous section should be strongly connected to the conservation of the @xmath4-component of the total momentum . [ pwdqypy ] [ pwdqypycont ] we consider a relation between the four - point steps in the model of this section and in the model of the previous section by investigating the graph of the quantity @xmath185 as a function of the normalized position @xmath147 and the collision number @xmath145 ( the graph [ _ b2 _ ] ) . [ pwdqypy ] is such graphs , and corresponds to the lyapunov exponent @xmath186 in the first four - point step ( fig . [ pwdqypy](a ) ) and the lyapunov exponent @xmath187 in the second four - point step ( fig . [ pwdqypy](b ) ) , which are indicated by arrows in fig . [ pwlya ] , in the same collision number interval @xmath188 $ ] . the wavelike structures of these graphs have a wavelength @xmath189 for the @xmath190-th four - point steps . the time - oscillating period corresponding to the lyapunov exponent @xmath186 is almost the same as the period @xmath164 of the first four - point steps of the previous model , and is approximately twice as long as the time - oscillating period in the lyapunov exponent @xmath187 of this model . these features are common with the four - point steps in the models of the previous section , suggesting that the four - point steps of the lyapunov spectrum in this model correspond to the four - point steps in the model of the previous section . we can also show that the quantities @xmath138 corresponding to the zero lyapunov exponents @xmath191 and @xmath123 are constants as functions of @xmath139 and @xmath145 approximately . now we proceed to investigate the graph of the quantities @xmath185 corresponding to the lyapunov exponents in the same four - point steps of the lyapunov spectrum . fig . [ pwdqypycont ] is the contour plots of these quantities as functions of the normalized position @xmath147 and the collision number @xmath145 , corresponding to the first four - point step consisting of the lyapunov exponents @xmath0 , @xmath192 and @xmath193 , in the same collision number interval @xmath194 $ ] . the corresponding lyapunov exponents are indicated by the brace under circles in fig . [ pwlya ] . in this case the contour lines of @xmath157 seem to be slanting , but if we pay attention of the mountain regions and the valley regions in these graphs then we can realize that the structure of these four graphs are similar to the contour plots of the four graphs in fig . [ ppdqypycont ] for the previous model . therefore the phase relations among the time - oscillating wavelike structures of the quantity @xmath158 can be summarized in the schematic illustration given in fig . [ phasecont1 ] like in the previous model . this suggests an approximate expression for the lyapunov vector components given by eq . ( [ lyapuoscil ] ) , for lyapunov vector components @xmath5 corresponding to the lyapunov exponents of the four - point steps in this model . as the next system we consider a quasi - one - dimensional system with hard - wall boundary conditions in the @xmath3-direction and periodic boundary conditions in the @xmath4-direction ( the boundary case [ _ a3 _ ] ) . a schematic illustration of such a system is given in fig . [ wp ] with solid lines for the hard - wall boundary conditions and broken lines for the periodic boundary conditions . -direction and periodic boundary conditions in the @xmath4-direction . the solid lines for the boundary means to take hard - wall boundary conditions , and broken lines for the boundary means to take periodic boundary conditions . ] [ wp ] in this system the @xmath3-component of the total momentum is not conserved , so the total number of the zero - lyapunov exponents is 4 . [ wplya ] is a small positive region of the lyapunov spectrum normalized by the maximum lyapunov exponent @xmath183 , including its stepwise structure , while its whole positive part of the lyapunov spectrum is given in the inset . the stepwise structure of the lyapunov spectrum is clearly different from the model of the previous subsection , and consists of two - point steps interrupted by isolated single lyapunov exponents . ( we call the isolated single lyapunov exponents interrupting the two - point steps the `` one - point steps '' in this paper from now on , partly because they are connected to the two - point steps in the model of sect . [ periopp ] as will shown in this subsection . ) as discussed in sect . [ periopp ] the lyapunov spectrum for the model with periodic boundary conditions in both directions has two - point steps and four - point steps , and it is remarkable that to adopt the hard - wall boundary conditions in the @xmath3-direction and to destroy the total momentum conservation in this direction halves the step - widths of both kinds of steps . [ wplya ] fig . [ wpdqy ] is the graphs of the time - averaged lyapunov vector components @xmath48 as functions of the normalized position @xmath52 ( the graph [ _ b1 _ ] ) , corresponding to the one - point steps . we can clearly recognize wavelike structures in these graphs , and in this sense the one - point steps in this model should be strongly related to the two - point steps in the model of sect . [ periopp ] . the lyapunov exponents accompanying wavelike structure of this kind of graphs are shown in fig . [ wplya ] as black - filled circle dots , meaning that they are the one - point steps . in fig . [ wplya ] we also filled the circle dots by gray for one of the zero - lyapunov exponents in which the graph of the lyapunov vector components @xmath48 as a function of the position @xmath104 is constant approximately . however it is important to note that the wavelength of the wave corresponding to the @xmath190-th one - point step in this model is @xmath195 , not @xmath189 like in the model of sect . [ periopp ] . we fitted the graphs corresponding to the lyapunov exponents @xmath0 , @xmath196 and @xmath160 by the functions @xmath197 respectively , with @xmath198 and @xmath60 as fitting parameters . here the values of the fitting parameters are chosen as @xmath199 , @xmath200 , @xmath201 and @xmath202 . the graphs are very nicely fitted by a constant or the sinusoidal functions , and lead to the form @xmath203 @xmath53 , of the lyapunov vector component @xmath126 corresponding to the lyapunov exponents @xmath127 in the @xmath37-th one - point step with constants @xmath204 and @xmath205 . [ wpdqy ] now we investigate the remaining steps , namely the two - point steps of the lyapunov spectrum . corresponding to these two - point steps of the lyapunov spectrum , the graphs of the quantity @xmath185 as functions of the normalized position @xmath147 and the collision number @xmath145 ( the graph [ _ b2 _ ] ) show spatial wavelike structures oscillating in time . it is shown in fig . [ wpdqypy ] for those graphs corresponding to lyapunov exponents ( indicated by arrows in fig . [ wplya ] ) in different two - point step , in the same collision number interval @xmath206 $ ] . the spatial wavelength of the waves corresponding to the @xmath190-th two - point step is @xmath195 , which is twice as long as the wavelength of waves of the four - point steps in the models in sect . [ periopp ] and the previous subsection . the period of time - oscillation of the wave corresponding to the @xmath190-th two - point step of the lyapunov spectrum is approximately given by @xmath207 with a constant @xmath208 . this kind of graph corresponding to one of the zero - lyapunov exponents , namely @xmath191 , is almost constant . [ wpdqypy ] it is important to note a relation between the time - oscillating period @xmath164 of the preceding two models and the time - oscillating period @xmath208 of the model in this section . noting that in figs . [ ppdqypy](a ) , [ pwdqypy](a ) and [ wpdqypy](a ) we plotted about one period of the time - oscillation of the wavelike structures of the quantities @xmath158 in the collision time intervals [ 543000,548100 ] , [ 390600,396000 ] and [ 222000,232200 ] , respectively , we can get an approximate relation @xmath209 . [ wpdqypycont ] as functions of the position @xmath139 and the collision number @xmath145 , corresponding to the first two - point step in the same collision number interval . thick gray lines means node lines , the region indicated by a red plus sign ( @xmath177 ) is the region where the quantity @xmath158 is positive , and the region indicated by a blue minus sign ( @xmath178 ) is the region where the quantity @xmath158 is negative . the phase of [ _ p1 _ ] is shifted in time from the phase of [ _ p2 _ ] by @xmath165 . ] [ phasecont2 ] the next problem is to investigate the graphs of the quantities @xmath185 as a function of the position @xmath139 and the collision number @xmath145 in the same two - point step of the lyapunov spectrum . [ wpdqypycont ] is the contour plots of such graphs for the first two - point step consisting of the lyapunov exponents @xmath0 , @xmath210 and @xmath211 , which is indicated by a brace under circles in fig . [ wplya ] , in the same collision number interval @xmath212 $ ] . it should be noted that the positions of the nodes of two spatial waves belonging to the same two - point step almost coincide with each other . however the phases of the time - oscillations of the amplitudes of the waves are shifted by about @xmath165 with each other . the phase relations of the graphs [ wpdqypycont](a ) and ( b ) is visualized in the schematic illustration given in fig . [ phasecont2 ] of the time - oscillating wavelike structures of the quantities @xmath158 corresponding to the first two - point step in the same collision number interval . here the phase [ _ p1_ ] and [ _ p2_ ] correspond to figs . [ wpdqypycont](a ) and ( b ) , respectively . a similar investigation of the lyapunov vectors shows that the time - oscillating wavelike structures for the second two - point steps are like the phases [ _ p1 _ ] and [ _ p2 _ ] of fig . [ phasecont1 ] except that the period @xmath164 in fig . [ phasecont1 ] should be replaced with the oscillating period @xmath208 of this model . these results suggest that the two - point steps in this model correspond to the four - point steps in the models of the previous subsection and sect . [ periopp ] , except for differences in the values of their wavelengths and time - oscillating periods . after all we get a conjecture that the lyapunov vector components @xmath166 and @xmath167 corresponding to the lyapunov exponents constructing the @xmath37-th two - point step are approximately expressed as @xmath213 @xmath53 with constants @xmath214 , @xmath215 and @xmath216 , noting the time - oscillating period @xmath217 . the last model is the case of hard - wall boundary conditions in both directions ( the boundary case [ _ a4 _ ] ) . a schematic illustration of this system is given in fig . [ ww ] in which the solid line of the boundary means to take hard - wall boundary conditions . [ ww ] a small positive region of the lyapunov spectrum normalized by the maximum lyapunov exponent @xmath218 is given in fig . [ wwlya ] . the graph for the full scale of the positive branch of the normalized lyapunov spectrum is also given in the inset of this figure . in this system the total momentum is not conserved any more , and the total number of zero - lyapunov exponents is 2 . the stepwise structure of the lyapunov spectrum consists of two - point steps only . in this model a wavelike structure in the lyapunov vector component @xmath184 as a function of the position @xmath100 ( the graph [ _ b1 _ ] ) is not observed . [ wwlya ] fig . [ wwdqypy ] is the graphs of the quantities @xmath138 as functions of the normalized position @xmath147 and the collision number @xmath145 ( the graph [ _ b2 _ ] ) , corresponding to the lyapunov exponents @xmath0 , @xmath219 and @xmath193 , in the same collision number interval @xmath220 $ ] . the corresponding lyapunov exponents are indicated by arrows in fig . [ wwlya ] . this figure for the two - point steps of the lyapunov spectrum shows a similar wavelike structure to the wavelike structure of the quantities @xmath138 in the model of the previous subsection , although one may think that fluctuations of these graphs in this model are much smaller than in the previous model . this suggest that the two - point steps of the lyapunov spectrum in fig . [ wwlya ] are similar to the two - point steps in the model of the previous subsection . the wavelength of the spatial waves and the the periods of the time - oscillations corresponding to the @xmath190-th two - point step are @xmath195 and @xmath207 , respectively , and the time - oscillating period of the first two - point step is given approximately by the same period @xmath208 @xmath221 as in the model of the previous subsection . it may also be noted that this kind of graph corresponding to the zero - lyapunov exponent @xmath191 is almost constant . [ wwdqypy ] fig . [ wwdqypycont ] is the contour plots of the quantities @xmath138 as functions of the normalized position @xmath147 and the collision number @xmath145 corresponding to the lyapunov exponents @xmath0 , @xmath222 and @xmath223 in the first two - point step of the lyapunov spectrum in the same collision number interval @xmath224 $ ] . the corresponding lyapunov exponents are indicated by the brace under circles in fig . [ wwlya ] . similarly to the previous model , the nodes of two spatial waves corresponding to the same two - point step almost coincide with each other , and the phase of the time - oscillation of the wave amplitudes is shifted by about @xmath165 . this also says that the phase relations of the graphs [ wwdqypycont](a ) and ( b ) is the types of the phases [ _ p1_ ] and [ _ p2_ ] in fig . [ phasecont2 ] . in a similar way we can see that the time - oscillating wavelike structures for the second two - point steps of the lyapunov spectrum for this model are like the phases [ _ p1 _ ] and [ _ p2 _ ] of fig . [ phasecont1 ] by replacing the period @xmath164 of fig . [ phasecont1 ] with the time - oscillating period @xmath217 of this model . these suggest an approximate expression for the lyapunov vector components given by eq . ( [ lyapuoscilwp ] ) , for lyapunov vector components @xmath5 corresponding to the lyapunov exponents of the @xmath37-th two - point steps in this model . the fact that the only difference between the model in this subsection and the model in the previous subsection is the boundary conditions in the @xmath4-direction suggests that the one - point steps of the model in the previous subsection come from the conservation of the @xmath4-component of the total momentum . [ wwdqypycont ] [ cols="^,^,^,^,^,^,^,^,^,^,^,^,^ " , ] [ sumar ] in this paper we have discussed numerically the stepwise structure of the lyapunov spectra and its corresponding wavelike structures for the lyapunov vectors in many - hard - disk systems . we concentrated on the quasi - one - dimensional system whose shape is a very narrow rectangle that does not allow exchange of disk positions . in the quasi - one - dimensional system we can get a stepwise structure of the lyapunov spectrum in a relatively small system , for example , even in a 10-particle system , whereas a fully two - dimensional system would require a much more particles . in such a system we have considered the following two problems : [ _ a _ ] how does the stepwise structure of the lyapunov spectra depend on boundary conditions such as periodic boundary conditions and hard - wall boundary conditions ? [ _ b _ ] how can we categorize the stepwise structure of the lyapunov spectra using the wavelike structure of the corresponding lyapunov vectors ? to consider the problem [ _ a _ ] also means to investigate the effects of the total momentum conservation law on the stepwise structure of the lyapunov spectra . in this paper we considered four types of the boundary conditions ; [ _ a1 _ ] periodic boundary conditions in the @xmath3- and @xmath4-directions , [ _ a2 _ ] periodic boundary conditions in the @xmath3-direction and hard - wall boundary conditions in the @xmath4-direction , [ _ a3 _ ] hard - wall boundary conditions in the @xmath3-direction and periodic boundary conditions in the @xmath4-direction , and [ _ a4 _ ] hard - wall boundary conditions in the @xmath3- and @xmath4-directions , in which we took the @xmath4-direction as the narrow direction of the rectangular shape of the system . with each boundary case we obtained different stepwise structures of the lyapunov spectra . in each boundary condition we also considered graphs of the following two quantities ; [ _ b1 _ ] the @xmath4-component @xmath5 of the spatial coordinate part of the lyapunov vector of the @xmath8-th particle corresponding to the lyapunov exponent @xmath0 as a function of the @xmath3-component @xmath6 of the spatial component of the @xmath8-th particle , and [ _ b2 _ ] the quantity @xmath10 with the @xmath4-component @xmath11 of the momentum coordinate of the @xmath8-th particle as a function of the position @xmath6 and the collision number @xmath145 . these quantities @xmath5 and @xmath10 give constant values in some of zero - lyapunov exponents , at least approximately . we found that the steps of the lyapunov spectra accompany a wavelike structure in the quantity @xmath5 or @xmath10 , depending on the kind of steps of the lyapunov spectra . a time - dependent oscillating behavior appears in the wavelike structure of the quantity @xmath10 , whereas the wavelike structure of the quantity @xmath5 is essentially stationary . fluctuations of these quantities @xmath5 and @xmath10 disturb their clear oscillatory structures , so we took a time - average of these quantities ( a local time - average for the quantity @xmath10 because of its time - oscillating behavior , and a longer time - average for the quantity @xmath5 because it is much more stationary in time than the quantity @xmath10 ) to get their dominant wavelike structures . in table . [ sumar ] we summarize our results about the characteristics of the stepwise structures of the lyapunov spectra and the wavelike structures of the lyapunov vectors in the four boundary cases [ _ a1 _ ] , [ _ a2 _ ] , [ _ a3 _ ] and [ _ a4 _ ] . in lyapunov exponents in each step of the lyapunov spectra the wavelike structures of the quantity @xmath5 or @xmath10 are approximately orthogonal to each others in space ( in the sense of eq . ( [ lyapuwave ] ) ) , in space and time ( in the sense of eq . ( [ lyapuoscil ] ) ) or in time ( in the sense of eq . ( [ lyapuoscilwp ] ) ) , and this fact suggests that the wavelike structure of these quantities are sufficient to categorize the stepwise structure of the lyapunov spectra in the quasi - one - dimensional systems considered in this paper . different from a purely two - dimensional model such as a square system in which each particle can collide with any other particle , in the quasi - one - dimensional model a separation between the stepwise region and the smoothly changing region of the lyapunov spectrum is not clear . in ref @xcite this point was explained as being caused by the fact that particles interact only with the two nearest - neighbor particles , whereas in the purely two - dimensional low - density system particles can interact with more than two particles . in this paper we considered the quasi - one - dimensional systems only . however there should be many interesting other situations in which we can investigate structures of the lyapunov spectrum and the lyapunov vectors . for example , we may investigate the effect of the rotational invariance of the system on such structures by considering a two - dimensional system with a circle shape . one might also investigate the system in which the orbit is not deterministic any more , in order to know whether the deterministic orbit plays an important role in the stepwise structure of the lyapunov spectrum or not . it may also be important to investigate the dependence of the stepwise structures of the lyapunov spectra on the spatial dimension of the system , for example , to investigate any structure of the lyapunov spectra for purely one- or three - dimensional many particle systems . ( note that the quasi - one - dimensional systems considered in this paper are still two - dimensional systems in the sense of the phase space dimension . ) these problems remain to be investigated in the future . the authors wish to thank c. p. dettmann and h. a. posch for valuable comments to this work . one of the author ( t.t ) acknowledges information on presentations of figures by t. yanagisawa . we are grateful for financial support for this work from the australian research council . a. de wijn and h. van beijeren , in _ international workshop and seminar on microscopic chaos and transport in many - particle systems _ ( max - planck - institut fr physik komplexer systeme , dresden , germany , 2002 ) , ( unpublished ) . forster and h. a. posch , in _ international workshop and seminar on microscopic chaos and transport in many - particle systems _ ( max - planck - institut fr physik komplexer systeme , dresden , germany , 2002 ) , ( unpublished ) .

boundary effects in the stepwise structure of the lyapunov spectra and the corresponding wavelike structure of the lyapunov vectors are discussed numerically in quasi - one - dimensional systems consisting of many hard - disks . four kinds of boundary conditions constructed by combinations of periodic boundary conditions and hard - wall boundary conditions are considered , and lead to different stepwise structures of the lyapunov spectra in each case . we show that a spatial wavelike structure with a time - oscillation appears in the spatial part of the lyapunov vectors divided by momenta in some steps of the lyapunov spectra , while a rather stationary wavelike structure appears in the purely spatial part of the lyapunov vectors corresponding to the other steps . using these two kinds of wavelike structure we categorize the sequence and the kinds of steps of the lyapunov spectra in the four different boundary condition cases . 0.455 cm

movements such as rapid cuts and stops , sudden accelerations , change of directions or jumps . therefore , effective performance requires an adequate level of lower limb power ( alemdarolu , 2012 ; litkowycz et al . , 2010 ) of which improvement is possible through the application of plyometric training based mainly on jumping exercises ( bobbert , 1990 ; litkowycz et al . , 2010 ; pietraszewski and struzik , 2013 ; young et al . , 1999 ) . the basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump ( dj ) ( bobbert , 1990 ; markovic , 2007 ; markovic and mikulic , 2010 ) . a bounce drop jump ( bdj ) is aimed to reverse downward velocity into an upward one as soon as possible after landing . on the contrary , a countermovement drop jump ( cdj ) , of which aim is to achieve the highest possible jump height , requires making a larger downward movement upon landing . therefore , the cdj is similar to the countermovement jump ( cmj ) ( bobbert et al . , 1987 ; bobbert , 1990 ; young et al . , 1995 ; young et al . , 1999 ) . obviously , it is possible to combine the cdj and bdj techniques to perform a jump with the maximum height and minimum ground contact time dj - h / t ( hunter and marshall , 2002 ; markwick et al . the bdj mainly improves lower limb power , whereas the cdj is oriented to improvement in jump height and coordination ( bobbert et al . , 1987 ; bobbert , 1990 ; young et al . , 1995 ; young et al . , 1999 ) . young et al . ( 1999 ) documented significantly higher values of reactive strength after a 6 week training program based on dj - h / t jumps . no such effect was observed in the group that followed a protocol based on the cdj . furthermore , markovic ( 2007 ) suggested that the effect of plyometric training was likely to have higher impact on vertical jump height in slow stretch - shortening cycle ( ssc ) jumps ( like the cmj ; the cdj can be also added to this group ) rather than in either concentric ( squat jump - sj ) or marshall and moran ( 2013 ) found that eight weeks of cdj training enhanced significantly cmj height , while a similar regime of the bdj training did not . ( 1987 ) showed that the mechanical output at knee and ankle joints reached larger values during the bdj than cdj . ( 2001 ) found that leg and ankle stiffness values were higher when the contact time during the dj ( directed by verbal instructions ) was shorter . furthermore , cressey et al . ( 2007 ) demonstrated that lower - body unstable surface training lead to a higher increase in power output for the bdj compared to cdj . differences in technique and variables that describe djs also occur for different heights of the platform from which the drop is performed ( ball et al . , 2010 ) or depending on the gender of the subjects ( laffaye and choukou , 2010 ) . bobbert ( 1990 ) concluded that dj technique was the most important variable to be controlled to ensure adequate training effects . ( 2004 ) also found that manipulation of jump technique played a greater role in control of important jump variables than the platform height . since jumping technique has a substantial effect on jumping variables , it is necessary to employ various standards for indices that control variables of the dj . an example of the index used for the dj which is susceptible to jumping technique is a reactive strength index ( rsi ) . the rsi is the quotient of the jump height and contact time ( mcclymont and hore , 2003 ) . theoretically , a higher value of the rsi reflects a more efficient performance of the movement in the stretch - shortening cycle . the value of the rsi can also change ( increase ) following plyometric training ( lloyd et al . , therefore , the aim of this study was to compare the values of the rsi for cdjs and bdjs . if the differences between the values of the rsi turned out to be substantial , this may suggest that dj variables should be carefully controlled ( including dj technique ) in a training cycle . according to the aforementioned reports , cdjs should be characterized by greater height of the jump and longer time of the contact phase compared to bdjs . therefore , maximal values of flexion in the lower limb and upper body joints should be significantly lower than for cdjs . finding significant differences between cdjs and bdjs for the variables of the jump height , contact time and the values of flexion in lower limb and upper body joints leads to the conclusion that the subjects were able to perform the above types of jumps using the demanded movement technique . the study was carried out in a group of 8 male youth basketball players ( age : 17.0 0.2 years ; body height : 188.4 6.4 cm ; body mass : 79.6 7.4 kg ; training experience : 4.4 1.6 years ) . the research project was approved by the ethics committee of the university school of physical education in wroclaw , poland , and the procedures complied with the declaration of helsinki regarding human experimentation . the tests were conducted using an amti bp600900 force plate ( watertown , ma , usa ) to measure ground reaction forces and the noraxon myomotion system ( scottsdale , az , usa ) to record kinematic data : cervical flexion - extension , lumbar flexion - extension , thoracic flexion - extension , hip flexion - extension , knee flexion - extension and ankle dorsi - plantar flexion angles . before the tests , each player performed jumping exercises in the following order : two cdjs and two bdjs from the height of 15 , 30 , 45 and 60 cm ( in sequence ) , with hands on the hips and elbows bowed outward ( total 16 jumps with a break after 8 jumps and a re - warm - up ) . in the case of the cdj , the participants were instructed to : jump as high as possible after the drop off from the platform . furthermore , for the bdj , the athletes were instructed to : jump up as fast as possible after contact with the ground and make sure that the jump is the highest possible . to initiate the drop action , step out from the platform one foot at a time ( right lower limb first ) . the participant was instructed to perform the contact phase ( amortization + take - off ) and landing phase on the force plate . myomotion reseach inertial sensors were placed according to the rigid - body model with 16 joint segments used in mr3 software on the right shoe ( top of the upper foot , slightly below the ankle ) , right shank ( frontal on the tibia bone ) , right thigh ( frontal attachment on a lower quadrant of quadriceps , slightly above the knee cap , area of lowest muscle belly displacement in motion ) , pelvic ( bony area of sacrum ) , lower thoracic ( on the spinal cord at approximately l1/t12 , the strap belt on the front body side positioned on lower ribs ) , upper thoracic ( below c7 along the spinal cord , but high enough not to be affected by upper trapezius muscle movement ) and head ( in the middle of the back of the head ) . calibration was carried out in an upright position of the subject in order to determine the value of the 0 angle in the joints studied . instantaneous changes in joint angles were recorded with respect to the transverse axis during jumps . recording of ground reaction forces during jumps allowed for determination of the time of contact and flight ( tf ) phases . consequently , the jump height ( h ) was calculated using the following formula : where g is the acceleration due to gravity . the rsi was calculated as a ratio of jump height ( mm ) and contact time ( ms ) ( mcclymont and hore , 2003 ) : recording the instantaneous changes in the knee joint angle during performance of jumps allowed for division of time of contact with the surface into amortization time ( ta ) and take - off time ( tt ) . thus , the rsi could also be calculated for the amortization and take - off phases separately ( pietraszewski and rutkowska - kucharska , 2011 ; struzik et al . , 2016 ) : the sampling rate for the signal from the force plate was set at 100 hz . compared to previous reports , rsi calculations and drop jump height measurements had acceptable reliability ( arteaga et al . , 2000 ; normality of distribution of each variable was tested using the shapiro - wilk and lilliefors tests . since the data was not normally distributed , the wilcoxon matched - pairs test was applied in order to evaluate the differences between the variables describing cdjs and bdjs . the study was carried out in a group of 8 male youth basketball players ( age : 17.0 0.2 years ; body height : 188.4 6.4 cm ; body mass : 79.6 7.4 kg ; training experience : 4.4 1.6 years ) . the research project was approved by the ethics committee of the university school of physical education in wroclaw , poland , and the procedures complied with the declaration of helsinki regarding human experimentation . the tests were conducted using an amti bp600900 force plate ( watertown , ma , usa ) to measure ground reaction forces and the noraxon myomotion system ( scottsdale , az , usa ) to record kinematic data : cervical flexion - extension , lumbar flexion - extension , thoracic flexion - extension , hip flexion - extension , knee flexion - extension and ankle dorsi - plantar flexion angles . before the tests , each participant was familiarized with the research goals . a 10 min warm - up was administered prior to the measurements . each player performed jumping exercises in the following order : two cdjs and two bdjs from the height of 15 , 30 , 45 and 60 cm ( in sequence ) , with hands on the hips and elbows bowed outward ( total 16 jumps with a break after 8 jumps and a re - warm - up ) . in the case of the cdj , the participants were instructed to : jump as high as possible after the drop off from the platform . furthermore , for the bdj , the athletes were instructed to : jump up as fast as possible after contact with the ground and make sure that the jump is the highest possible . to initiate the drop action step out from the platform one foot at a time ( right lower limb first ) . the participant was instructed to perform the contact phase ( amortization + take - off ) and landing phase on the force plate . myomotion reseach inertial sensors were placed according to the rigid - body model with 16 joint segments used in mr3 software on the right shoe ( top of the upper foot , slightly below the ankle ) , right shank ( frontal on the tibia bone ) , right thigh ( frontal attachment on a lower quadrant of quadriceps , slightly above the knee cap , area of lowest muscle belly displacement in motion ) , pelvic ( bony area of sacrum ) , lower thoracic ( on the spinal cord at approximately l1/t12 , the strap belt on the front body side positioned on lower ribs ) , upper thoracic ( below c7 along the spinal cord , but high enough not to be affected by upper trapezius muscle movement ) and head ( in the middle of the back of the head ) . calibration was carried out in an upright position of the subject in order to determine the value of the 0 angle in the joints studied . sampling frequency for the inertial sensors instantaneous changes in joint angles were recorded with respect to the transverse axis during jumps . recording of ground reaction forces during jumps allowed for determination of the time of contact and flight ( tf ) phases . consequently , the jump height ( h ) was calculated using the following formula : where g is the acceleration due to gravity . the rsi was calculated as a ratio of jump height ( mm ) and contact time ( ms ) ( mcclymont and hore , 2003 ) : recording the instantaneous changes in the knee joint angle during performance of jumps allowed for division of time of contact with the surface into amortization time ( ta ) and take - off time ( tt ) . thus , the rsi could also be calculated for the amortization and take - off phases separately ( pietraszewski and rutkowska - kucharska , 2011 ; struzik et al . , 2016 ) : the sampling rate for the signal from the force plate was set at 100 hz . compared to previous reports , rsi calculations and drop jump height measurements had acceptable reliability ( arteaga et al . , 2000 ; beattie and flanagan , 2015 ; markwick et al . , 2015 ) . normality of distribution of each variable was tested using the shapiro - wilk and lilliefors tests . since the data was not normally distributed , the wilcoxon matched - pairs test was applied in order to evaluate the differences between the variables describing cdjs and bdjs . table 1 presents mean values ( sd ) of jumping variables and the rsi during cdjs and bdjs . statistically significant differences ( p < 0.05 ) between rsi values for cdjs and bdjs were recorded for jumps from 30 , 45 and 60 cm . differences in rsi values for jumps from 15 cm were not statistically significant . furthermore , cdj height values were significantly higher ( p < 0.05 ) than the values recorded for bdjs . time of contact , amortization and take - off during bdjs was significantly shorter ( p < 0.05 ) than the respective values obtained for cdjs . . significant differences at p < 0.05 cdj countermovement drop jump , bdj bounce drop jump , rsi reactive strength index , difference between variables that describe cdjs and bdjs , table 2 shows mean values ( sd ) of maximum angles during cdjs and bdjs . positive values of the angles correspond to flexion and dorsi - flexion . statistically significant differences ( p < 0.05 ) were found between cdjs and bdjs in maximum values of angles of flexion in the knee and hip joints ( from the height of 15 , 30 , 45 and 60 cm ) and thoracic extension ( from the height of 15 , 30 and 45 cm ) . mean values ( sd ) of maximum angles during cdjs and bdjs . significant differences at p < 0.05 cdj countermovement drop jump , bdj bounce drop jump , difference between maximum angles during cdjs and bdjs , the technique of dj performance causes that cdjs are higher than bdjs , with elongation of the contact time ( table 1 ) . in the present study , the increased contact time resulted from the elongation of both the amortization and take - off phases . this is consistent with previous reports concerning influence of dj performance instruction ( bobbert et al . , 1987 ; bobbert , 1990 ; young et al . , 1995 ; differences in time of contact with the ground are also accompanied by the differences in maximal angles of flexion in knee and hip joints and thoracic extension . longer time of the take - off during cdjs leads to an increase in angles of flexion in the knee and hip joints and thoracic extension . greater height of cdjs compared to bdjs may result from a greater range of motion in the knee , hip and thoracic joints that allows to obtain greater angular velocities in these joints ( bober et al . however , differences in the techniques of cdj and bdj performance do not induce significant differences in maximum values of angles during movements in the cervical and lumbar joints and , surprisingly , the ankle joint . based on the differences recorded for the variables that describe cdjs and bdjs , it can be concluded that the study participants performed both types of jumps effectively . therefore , it may be stated that the technique of the dj is affected by the instruction to perform the exercise ( young et al . some training studies have found that plyometric training based on djs does not significantly enhance jump height or lower limb power , while other reports showed a large variability in the magnitude of such enhancement . several factors , including a training program design ( the type of exercises , training duration , training frequency , volume and intensity of training ) , subject characteristics ( age , gender , fitness level , sport practice ) and methods of testing different types of vertical jumps may be responsible for the conflicting findings concerning plyometric training . however , potentially inconsistent effects of dj training may result from the differences in the dj technique employed ( bobbert , 1990 ; markovic , 2007 ; markovic and mikulic , 2010 ) . the rsi is mostly used to profile stretchload tolerance and to identify appropriate platform heights for the performance of drop jumps . the modification of the rsi ( rsi take - off ) allows not only for a more detailed control of the athlete over the training process , but also for its utilization for the cmj ( pietraszewski and struzik , 2013 ; pietraszewski et al . , 2015 ; suchomel et al . , statistically significant differences in jump height , contact , amortization and take - off times between cdjs and bdjs induce significant differences , also in rsi value ( for dj from 30 , 45 and 60 cm ) . differences in rsi values for jumps from 15 cm were not significant , which can be explained by a relatively low height of the platform . ( 1986 ) observed that when performing a dj , some subjects spontaneously chose to make a large amplitude movement after a drop ( cdj ) , whereas others preferred a small amplitude movement ( bdj ) . if drop height is increased and jump technique is not controlled , subjects are likely to make a larger downward movement upon landing . therefore , the dj technique will shift from the bdj to cdj ( bobbert , 1990 ; hunter and marshall , 2002 ) . to conclude , the use of the rsi to monitor plyometric training should refer to the dj expected performance technique . it is also necessary to control dj technique since performing a jump which does not meet the specific criteria may impact jumping variables and rsi values . it should be expected that rsi values will be slightly higher for bdjs than cdjs . due to differences in jumping technique , djs from the same platform height the limitations of this study may be a small size and type ( young basketball players ) of the studied group . it should be also emphasized that the use of the force plate allowed computation of the jump height based on the duration of the flight phase , which eliminated the effect of individual variables ( such as foot or upper limb length ) . we realize that determination of the jump height based on the flight phase duration has some limitations and is not a perfect method .

abstractthe basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump . this exercise can be performed using different techniques , which substantially affects jump variables . therefore , the aim of this study was to compare the values of the reactive strength index ( rsi ) for countermovement drop jumps ( cdjs ) and bounce drop jumps ( bdjs ) . the study was carried out in a group of 8 male youth basketball players . the tests were conducted using the amti bp600900 force plate to measure ground reaction forces and the noraxon myomotion system to record kinematic data . each player performed two cdjs and two bdjs from the height of 15 , 30 , 45 and 60 cm . the rsi was calculated as a ratio of jump height and contact time . moreover , the rsi was determined for the amortization and take - off phases separately . significant differences ( p < 0.05 ) between rsi values for cdjs and bdjs were recorded for jumps from 30 , 45 and 60 cm . differences in rsi values for jumps from 15 cm were not significant . furthermore , cdj height values were significantly higher ( p < 0.05 ) than the values recorded for bdjs . times of contact , amortization and take - off during bdjs were significantly shorter ( p < 0.05 ) than the respective values obtained for cdjs . therefore , the use of the rsi to monitor plyometric training should be based on the drop jump technique that is commonly performed by basketball players .

A new planet has been discovered orbiting a distant star - the smallest yet detected outside our own Solar System. The mini-world, the size of the Moon, is described as hot and barren and thought to be like a small version of Mercury. The planet's close orbit to its star - Kepler-37 - means it would be too hostile to support life but scientists say its discovery is significant as it shows that it should be possible to spot Earth-type planets, if there are any out there. They have called the new world Kepler-37b, after the star. It is one of three planets discovered orbiting the star. Kepler-37c is smaller than Earth; Kepler-37d is much bigger. Professor Bill Chaplin, from the University of Birmingham's School of Physics and Astronomy, said: "This research shows for the first time that other stellar systems host planets much smaller than anything in our solar system. "This helps us to put our own solar system into a wider context." Until recently, the only planets found orbiting stars outside the solar system were Jupiter-like "gas giants" made mostly of hydrogen and helium. They are often many times the size of Earth and as a result have been easier to detect. Newer techniques are now turning up increasing numbers of small, rocky planets, like the inner planets of our own solar system; Mercury, Venus, Earth and Mars. Such worlds offer the best chance of finding life among the stars. 51 Pegasi-b was the first exoplanet found, in 1995 (artist's impression) Orbiting very close to its parent star, Kepler-37b is likely to have no atmosphere and have a surface blasted by heat and radiation. The planet was detected by the Kepler space telescope, which is surveying more than 145,000 stars in our galaxy, the Milky Way. The Kepler telescope - which orbits the Sun, rather than the Earth - is designed to measure the tiny reduction in starlight that occurs when a planet moves in-between the telescope and a distant star. It is kept constantly pointing at the same part of the galaxy to record any changes in light emitted from any one of the thousands of stars it is observing. British scientists from the University of Birmingham were among the international team that analysed the data. So far, Kepler has found 2,740 stars which may have Earth-sized planets orbiting them. In January 2013, astronomers at the Harvard-Smithsonian Centre for Astrophysics used Kepler's data to estimate that there are "at least 17 billion" Earth-sized planets in the Milky Way galaxy. The first planet found outside the Solar System circling a sun-like star was 51 Pegasi-b, discovered in 1995. Such bodies are called exoplanets. The research is reported in the journal Nature. ||||| Astronomers searching for planets outside our solar system have discovered the tiniest one yet _ one that's about the size of our moon. But hunters for life in the universe will need to poke elsewhere. The new world orbits too close to its sun-like star and is too sizzling to support life. Its surface temperature is an estimated 700 degrees Fahrenheit (371 degrees Celsius). It also lacks an atmosphere and water on its rocky surface. University of California, Berkeley astronomer Geoff Marcy, one of the founding fathers of the planet-hunting field, called the latest find "absolutely mind-boggling." "This new discovery raises the specter that the universe is jampacked, like jelly beans in a jar, with planets even smaller than Earth," said Marcy, who had no role in the new research. It's been nearly two decades since the first planet was found outside our solar system. Since then, there's been an explosion of discoveries, accelerated by NASA's Kepler telescope launched in 2009 to search for a twin Earth. So far, 861 planets have been spotted and only recently have scientists been able to detect planets that are similar in size to Earth or smaller. While scientists have theorized the existence of a celestial body that's smaller than Mercury _ the baby of the solar system since Pluto's downgrade _ they have not spotted one until now. Nearest to the sun, Mercury is about two-fifths the Earth's diameter; the newly discovered planet and our moon are about a third the size of Earth. The teeny planet was detected by Kepler, which simultaneously tracks more than 150,000 stars for slight dips in brightness _ a sign of a planet passing in front of the star. The planet _ known as Kepler-37b _ orbits a star 210 light years away in the constellation Lyra. It's one of three known planets in that solar system. Discoverer Thomas Barclay of the NASA Ames Research Center in Northern California was so excited when he spied the moon-sized planet that for days, he said he recited the "Star Wars" movie line: "That's no moon." It took more than a year and an international team to confirm that it was a bona fide planet. The discovery is detailed in Thursday's issue of the journal Nature. Scientists are looking for an Earth-size planet that's in the so-called Goldilocks zone _ that sweet spot that's not too hot and not too cold where water, which is essential for life, could exist on the surface. While the newly discovered planet isn't it, "that does not detract from the fact that this is yet another mile marker along the way to habitable Earth-like planets," said Alan Boss of the Carnegie Institution for Science in Washington, who was not part of the discovery team. ___ Follow Alicia Chang at http://twitter.com/SciWriAlicia

– Scientists have discovered the smallest known planet, just a third of the size of the Earth. Mercury, the smallest in our solar system, is two-fifths Earth's size, the AP notes; the new discovery, Kepler-37b, is a far-off exoplanet. "This research shows for the first time that other stellar systems host planets much smaller than anything in our solar system," says a scientist. The ability to spot this planet—via the Kepler telescope—suggests researchers are now capable of finding distant Earth-like planets, Sky News notes. But don't pack your bags just yet: The new planet is pretty close to its sun-esque star, resulting in rather balmy 700-degree temps on its surface. Further making life inhospitable: No atmosphere or water. Still, "this new discovery raises the specter that the universe is jampacked, like jelly beans in a jar, with planets even smaller than Earth," says one expert.

It’s an age old question: Why do zebras have stripes? There have been many theories -- four of them, to be exact -- according to researchers of a new study. The issue isn’t so black and white, it appears. The four theories include confusing predators, regulating temperature, helping zebras recognize each other and avoiding biting flies. However, temperature has the highest correlation to the number of stripes on a zebra, the researchers reported in the journal Royal Society Open Science. They also found that the warmer it is, the more stripes a zebra has. Brenda Larison, co-author of the study, told ABC News that there are two ways temperature could affect striping. One is called the “cooling eddy” theory that suggests there are opposing airflows on a zebra’s black and white stripes because of the different speeds heat rises on black and white fur. At the intersections of these currents, there are whirlpools of air that cool their skin. These cooling swirls of air could also repel biting insects that prefer the heat, such as tsetse flies. The researchers of the study came to this conclusion by checking the relationship between stripes and 29 different environmental factors at 16 different wildlife sites within Central and Southern Africa. They also chose to study zebras that live on plains because they are the most common. Larison said the study is the first to look at the correlation between all the theories, which had only been tested one at a time until now. “What we really feel is important about our study is that most studies so far have only taken one hypothesis and studied it by itself,” said Larison, “but that doesn’t help disprove or help prove the others. We made an effort to throw some of these ideas against each other.” Larison adds that they think there are still more complex and multiple factors that influence striping, so for now, the issue still isn’t so black and white. ||||| Plains zebras living in central Africa, like this one in Uganda, tend to have more defined stripes than plains zebras living in more Southern, cooler regions of Africa. Zebras' thick, black stripes may have evolved to help these iconic creatures stay cool in the midday African heat, a new study suggests. Many African animals sport some stripes on their bodies, but none of these patterns contrast as starkly as the zebra's. Researchers have long struggled to explain the purpose of the zebra's unique black-and-white coat. Some have suggested that the stripes may help zebras camouflage themselves and escape from lions and other predators; avoid nasty bites from disease-carrying flies; or control body heat by generating small-scale breezes over the zebra's body when light and dark stripes heat up at different rates. Still, few scientists have tested these explanations, and many argue that the stripes serve a complex mix of purposes. [See images of plains zebras across southern Africa] Now, researchers based at the University of California, Los Angeles (UCLA) have produced one of the most comprehensive zebra stripe studies yet by examining how 29 different environmental variables influence the stripe styles of plains zebras at 16 different sites from south to central Africa. The scientists found that the definition of stripes along a zebra's back most closely correlated with temperature and precipitation in a zebra's environment, and did not correlate with the prevalence of lions or tsetse flies in the region. These findings suggest that torso stripes may do more to help zebras regulate their body temperature than to avoid predators and tsetse flies, the team reported Tuesday (Jan. 13) in the journal Royal Society Open Science. "This wall we kept hitting up against was, 'Well, why do zebra have to have stripes for predation? Other animals have predators, and they don't have stripes,'" said study co-author Ren Larison, a researcher in the Department of Ecology and Evolutionary Biology at UCLA. "And other animals get bitten by flies, and they don't have stripes, either." Other animals also need to regulate body temperature, or thermoregulate, Larison pointed out, but zebras may especially benefit from an extra cooling system because they digest food much less efficiently than other grazers in Africa. As such, zebras need to spend longer periods of time out in the heat of the midday sun, eating more food. "Zebra have a need to keep foraging throughout the day, which keeps them out in the open more of the time than other animals," Larison told Live Science. "An additional cooling mechanism could be very useful under these circumstances." The team found that the plains zebras with the most-defined torso stripes generally lived in the Northern, equatorial region of their range, whereas those with less-defined torso stripes were more common in the Southern, cooler regions of the range — a finding that supports the thermoregulation explanation. Still, the researchers have not experimentally tested the theory that black and white stripes may generate small-scale breezes over a zebra's body, and some researchers don't think stripes can actually create this effect. "I don't think that you would want to have a lot of black hairs along the top of your back if you wanted to try to keep cool," said Tim Caro, a professor of wildlife biology at the University of California, Davis, who studies zebra stripes but was not involved in the new study. "It's kind of the last color that you would want." Caro said regions with warmer, wetter climates are particularly susceptible to several species of disease-carrying flies other than the tsetse fliesthat the team considered in their study, and that the relationship the researchers found may actually be a function of fly avoidance, not thermoregulation. Flies seem to struggle to recognize striped surfaces, but scientists have not quite figured out why this is, Caro told Live Science. The study co-authors emphasized that their findings require follow-up research, and that a zebra's stripes likely serve multiple purposes. For example, stripes on a zebra's back may help thermoregulate, whereas stripes on the animal's legs — where zebras are more likely to get bitten by flies — may help them avoid disease-carrying flies other than tsetses, Larison said. "Really, the striping is kind of extraordinary, so you need something extraordinary to explain it," Larison said. The researchers plan to test their thermoregulation hypothesis, either by studying the behavior of air currents over zebra pelts, or by implanting wild zebras with temperature sensors, if they are granted permission to do so, Larison said. Follow Laura Poppick on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science.

– There are all kinds of explanations out there for why zebras have stripes, ranging from tricking lions to putting off bugs. A new study helps clarify the situation: Zebras' stripes appear to be linked to temperature, National Geographic reports. Zebras living in warmer temperatures have more stripes than their cousins in colder weather, and researchers wanted to find out why. Investigating 16 different zebra populations, they looked at 29 features of their various environments, from soil to disease prevalence. Seeking a link between these features and the zebras' various stripe patterns, they found the strongest connection involved temperature. The link was so strong that scientists, armed with temperature data, were able to predict stripe patterns among other zebra populations. One reason for the connection might be that the way air interacts with the different colors could help keep zebras cool. Because they're not so efficient at digesting food, zebras have to keep eating—under a hot sun—more often than other animals, making cooling important, LiveScience reports. The stripes may also keep away disease-carrying bugs, who like hot areas and don't like stripes. The specifics remain unclear, but the study sheds some light on the subject. "What we really feel is important about our study is that most studies so far have only taken one hypothesis and studied it by itself," a researcher tells ABC News. "We made an effort to throw some of these ideas against each other.” One thing that seems clear: Stripe patterns aren't connected to the local lion population. (Here's more evidence the stripes are there to deter biting flies.)

semiconductor quantum dots form a promising platform for quantum optics devices , including single photon emitters and emitters of entangled photon pairs . @xcite the quantum dot - based light sources can be characterized by means of photon - photon correlation spectroscopy , i.e. by measuring the second - order correlation function @xmath0 between two photons with the delay @xmath1.@xcite multiple experimental observations of the antibunching [ @xmath2 of the photons emitted from the quantum dots are already available.@xcite one of the possible routes to further enhance the performance of these light sources is to resonantly couple the quantum dot exciton with the photonic mode , confined inside the microcavity in all three spatial directions.@xcite the physics of such quantum microcavites becomes especially rich in the strong coupling regime , where the new quasiparticles , exciton polaritons , are formed due to the interaction between the excitons and the cavity photons.@xcite here , we study the time dependence of the second - order correlations between the photons , emitted from the quantum dot microcavity . we analyze the case of incoherent nonresonant pumping of the excitons inside the quantum dot . this is a specific feature of the considered problem , different from the resonant fluorescence scheme , generally employed in atomic cavities.@xcite comprehensive studies of the stationary function @xmath3 have been carried out in refs . . it has been demonstrated , that the value of @xmath3 increases with pumping strength and exhibits qualitatively different behavior in weak and strong coupling regimes . hence , we focus our attention on the temporal dynamics of the correlations . our main goal is to derive transparent analytical answers for the correlation function @xmath0 as function of pumping both in strong and in weak coupling regimes . we show , how the lifetime of the polariton eigenstates determines the correlation decay rate , and how the spacings between the polariton energy levels are manifested in the rabi oscillations . we consider the stationary pumping case , favorable for studies of the time dependence of the correlations . experimentally , such regime can be realized in quantum dot microcavities driven by electrical pumping @xcite or continuous optical pumping . this situation should be distinguished from the case of pulsed pumping,@xcite where the time dependence of the signal depends on the individual pulse shape.@xcite the rest of the paper is organized as follows . in sec . [ sec : model ] the model and the calculation approach are described . [ sec : strong ] and sec . [ sec : weak ] present the theory developed in strong and weak coupling regimes , respectively . paper results are summarized in sec . [ sec : summary ] . auxiliary derivations are given in appendices [ aps ] and [ apq ] . we consider zero - dimensional microcavity where the single photon mode is coupled to the single excitonic state of the quantum dot . polarization degrees of freedom of both photons and excitons are disregarded for simplicity . under these assumptions the hamiltonian of the studied system has the standard form@xcite @xmath4 here , @xmath5 is the resonance frequency of the cavity , tuned to the exciton resonance , @xmath6 and @xmath7 are the bosonic annihilation and creation operators for cavity mode ( @xmath8=1 $ ] ) , @xmath9 and @xmath10 are corresponding `` fermionic '' operators for the single exciton mode ( @xmath11 , @xmath12 ) , and @xmath13 is the light - exciton coupling constant . . corresponds to the quantum dot smaller than the exciton bohr radius . to consider the case of large quantum dot one should generalize the model of refs . . in order to determine the intensity of emission from the cavity one should also introduce the processes of particles generation and decay . we consider incoherent continuous pumping of excitons into the quantum dot with the rate @xmath14 . more detailed discussion of the pumping mechanism can be found in ref . . excitonic mode is characterized with the non - radiative damping @xmath15 . photons can escape the cavity through the mirrors with the rate @xmath16 . hence , the full system state is described by the density matrix @xmath17 and its evolution is determined by the equation @xmath18 $ ] with the lindblad terms in the liouvillian @xmath19 , accounting for damping and pumping:@xcite @xmath20 = -\frac{{{\rm i}}}{\hbar}[h,\rho ] + \frac{{\gamma_{\rm c}}}{2}(2c \rho c^\dag - c^\dag c \rho - \rho c^\dag c ) \\ & + \frac{{\gamma_{\rm x}}}{2}(2b \rho b^\dag - b^\dag b \rho - \rho b^\dag b ) + \frac{w}{2}(2b^\dag \rho b - b b^\dag \rho - \rho b b^\dag ) \nonumber \:.\end{aligned}\ ] ] stationary density matrix @xmath21 satisfies the equation @xmath22=0 $ ] . one can calculate the number of photons in cavity @xmath23 and the exciton occupation number @xmath24 as @xmath25 where @xmath26 stands for the operator trace and angular brackets denote the quantum mechanical expectation value . detailed study of the dependence of these numbers on the pumping and on the other parameters can be found in refs . . the goal of this work is to analyze the time dependence of the fluctuations of the emission intensity from the cavity . they are described by the correlator @xmath0 determining the probability to register two photons with the time delay @xmath1:@xcite @xmath27 eq . presents the simplest definition of the correlation function , suitable for the following analytical treatment . the more general expression , taking into account the finite response rate and spectral window of the photon detector for two- and multiple- photon correlations is given in ref . . the way of calculation of @xmath0 is provided by the quantum regression theorem,@xcite @xmath28 \:,\ ] ] where the evolution of the operator @xmath29 $ ] is governed by the dynamic equation @xmath30 \ : , \quad \chi(0 ) = c \rho_0 c^\dag \:.\ ] ] for zero time delay eq . assumes the form @xmath31 for large time delays the correlator tends to unity , @xmath32 , because the probabilities of detection of two photons become independent . in this section we analyze the time dependence @xmath0 in the strong coupling regime , when @xmath33 . we first present a general overview of the results and then provide a detailed analytical description in different regimes , determined by the strength of pumping . our main calculation results are summarized in fig . [ fig : strong ] . panel ( a ) shows the dynamics of the correlator @xmath0 , while panels ( b ) and ( c ) present the average lifetime of the correlations @xmath34t}{\int_0^\infty { \rm d}t [ g^{(2)}(t)-1]}\label{eq : decay_time}\ ] ] and the stationary value @xmath3 , respectively . [ fig : strong ] demonstrates , that the dependence of the time - resolved correlations on pumping is not trivial . in sec . [ sec : low] [ sec : high ] the following qualitatively different regimes are described : \(a ) _ low pumping _ , @xmath35 . in this case the correlation function @xmath0 is less than unity at @xmath36 ( antibunching ) and demonstrates rabi oscillations with the frequency @xmath37 . the decay rate of the oscillations is equal to the average of the exciton and photon decay rates . \(b ) _ moderate pumping _ , @xmath38 . growth of the pumping intensity leads to the decrease of both the period and the lifetime of the oscillations . in a wide range of higher pumping intensities @xmath39 the emission statistics is gaussian and the correlation function is close to unity and almost time - independent . this can be understood as a lasing regime for the dot , strongly coupled to the cavity mode . high pumping_. the pumping value @xmath40 corresponds to the transition from the lasing regime to the so - called self - quenching regime.@xcite as the pumping rate crosses the critical point @xmath41 the stationary correlator @xmath3 exhibits an abrupt growth , while the correlation lifetime @xmath42 demonstrates non - monotonous behavior with a sharp peak . it rises as @xmath43 near the critical point @xmath44 . the peak height is on the order of @xmath45 , and much larger than the value of the correlation time in all other regimes . at large pumping @xmath46 the strong coupling regime is destroyed : the emission statistics is thermal [ @xmath47 and the decay time of the correlations equals to the empty cavity mode lifetime @xmath48 . now we proceed to more detailed analysis of the regimes ( a)(c ) . the density matrix equations can be conveniently analyzed using the basis of the eigenstates of the hamiltonian ( [ eq : ham ] ) , which are well defined in strong coupling regime . the eigenstates read@xcite @xmath49 where @xmath50 and @xmath51 stand for the states with @xmath52 photons and no excitons or one exciton , respectively . the energy spectrum forms the jaynes - cummings ladder @xmath53 each rung of the ladder contains two states split by the rabi frequency @xmath54 , increasing with the rung number @xmath52 . in the limit of vanishing pumping @xmath55 it is sufficient to take into account only the rungs with @xmath56 particles , which yields the following correlation function , @xmath57 eq . shows the oscillations of the photon - photon correlator . this is the direct manifestation of the strong coupling regime . due to the photon - exciton interaction @xmath13 the photon is fully converted into exciton and vice versa every period @xmath58 ( rabi oscillations ) . this results in the contribution to the correlator , oscillating with the rabi frequency of the first rung @xmath59 . the decay rate of the rabi oscillations is the average of the photon and exciton decay rates @xmath60 . this is also a manifestation of strong coupling and shows formation of the excitonic polaritons . for realistic cavities @xmath61,@xcite which means that @xmath62 ( antibunching).@xcite the black dotted curve in the fig . [ fig : strong](a ) is plotted after eq . and well reproduces the numerical results for low pumping rate ( black solid curve ) . in contrast to the low pumping case ( sec . [ sec : low ] ) , for moderate pumping it is necessary to take into account all of the rungs . first , one needs to determine the stationary density matrix @xmath63 . as shown in appendix [ aps ] this matrix @xmath63 is diagonal in the basis of states ( [ eq : basis ] ) and has the elements @xmath64 , @xmath65 , where the distribution function @xmath66 reads @xmath67 here , @xmath68 is the dimensionless pumping , @xmath69 , @xmath70 and @xmath71 are the gamma and error functions , respectively . for simplicity in this section the exciton decay rate @xmath15 is neglected , since for typical microcavities @xmath72.@xcite equation generalizes the analytical result for the distribution function obtained in ref . . the distribution eq . provides the following expressions for the particle numbers and the stationary correlator @xmath3 : @xmath73}{8w^2(e+1)^2 } \nonumber \:.\end{aligned}\ ] ] of ( a ) exciton number @xmath74 , ( b ) photon number @xmath75 , ( c ) correlation function @xmath3 , and ( d ) correlation decay time @xmath42 , plotted for various coupling strengths @xmath13 and @xmath76 . solid lines are obtained from numerical calculation . dashed lines in panels ( a)-(c ) present weak coupling regime and are plotted after eqs . ( [ nxc_weak ] ) and ( [ g20_weak ] ) , while dotted lines correspond to the strong coupling limit , eqs . ( [ eq : ng2_strong ] ) . dash - dotted lines in panels ( a)-(d ) show the analytic results obtained at high pumping regime eq . and and valid outside the patterned region @xmath77 for the parameters chosen . thin dotted lines in panel ( d ) correspond to the range of pumping , where the function @xmath0 is close to @xmath78 and the definition of @xmath42 according to eq . fails . ] solid curves in the figs . [ fig : static](a)[fig : static](c ) show the dependence of @xmath74 , @xmath75 and @xmath3 on the pumping rate . the curves are presented at the different values of exciton - photon coupling strength @xmath13 . results in figs . [ fig : static](a)[fig : static](c ) agree with those obtained numerically in ref . . here we focus on the strong coupling regime ( black curves ) , the weak coupling case will be analyzed in sec . [ sec : weak ] . the dot population @xmath74 [ see fig . [ fig : static](a ) ] monotonously increases at low pumping as @xmath79 and reaches the plateau @xmath80 at @xmath81 . the plateau @xmath80 reflects the half - exciton half - photon nature of the polariton eigenstates eq . with @xmath82 . photon number @xmath83 [ see fig . [ fig : static](b ) ] linearly grows for low and moderate pumping as @xmath84 and @xmath85 , respectively . the second - order correlator @xmath3 [ see fig . [ fig : static](c ) ] grows with pumping and reaches the plateau @xmath86 at @xmath81 ( lasing regime@xcite ) . in the moderate pumping regime all the curves @xmath74 , @xmath75 and @xmath3 are well described by eq . ( [ eq : ng2_strong ] ) , see black dotted curves . now we proceed to the discussion of the dynamics of @xmath0 . two independent contributions can be singled out in the time dependence , see fig . [ fig : strong](a ) : ( i ) the oscillatory contribution and ( ii ) the monotonously decaying contribution . as shown in appendix [ aps ] , the oscillatory term demonstrates the superposition of the rabi beatings between the split states inside different rungs of jaynes - cummings ladder with the frequencies @xmath87 . the weight of the term corresponding to the rung @xmath52 is determined by the distribution function @xmath88 . the damping of the oscillations is due to the stimulated photon decay and exciton pumping and equals to @xmath89 . non - oscillating term decays in time towards unity on the time scale of @xmath16 . calculation shows that this decay can be approximated as exponential one with the rate @xmath90 , @xmath91^{-1}\:.\ ] ] for small pumping @xmath92 eq . reduces to @xmath93 , whereas for moderate pumping @xmath94 one gets @xmath95 . resulting expression for the correlator @xmath0 assumes the form @xmath96 t } \ : . \nonumber\end{aligned}\ ] ] for low pumping the sum in eq . ( [ eq : g2t_strong ] ) is determined by the first term with @xmath97 and the result agrees with eq . ( [ eq : g2t_strong_linear ] ) assuming @xmath98 . analytical results plotted after eq . ( [ eq : g2t_strong ] ) are shown in the fig . [ fig : strong](a ) by dashed curves . the difference from the exact calculation at small pumping is due to the neglected exciton decay rate @xmath15 . well reproduces the main features of the numerically calculated dependence : for larger pumping the amplitude of the oscillations significantly decreases and they decay faster . this is a characteristic feature of the two - level system , distinct from the bosonic system where the lifetime of fluctuations increases with pumping.@xcite when the pumping rate is increased up to @xmath100 the exciton level broadening caused by pumping becomes comparable to the rung splitting . this results in saturation of exciton number at unity [ see fig . [ fig : static](a ) ] and drastic decrease of the photon number [ see fig . [ fig : static](b ) ] . the detailed description of stationary density matrix and correlator dynamics equations is given in appendix [ apq ] . it is shown that the emission statistics changes qualitatively when the pumping rate crosses the critical value @xmath101 . for lower than critical pumping the distribution function is gaussian , while for larger pumping it becomes thermal . the transition occurs in the vicinity of critical point @xmath102 . below we present the analytical expressions for emission characteristics valid outside this narrow region . the static characteristics for @xmath103 are given by @xmath104 dash - dotted lines in figs . [ fig : static](a)[fig : static](c ) present the dependence of @xmath74 , @xmath75 and @xmath3 on the pumping rate near the critical point @xmath41 plotted after eq . . one can see the perfect agreement of the analytical results with the numerical calculation ( black solid curve ) outside the narrow patterned transition region . the time dependence of the correlator @xmath0 is mono - exponential , @xmath105 \,{{\rm e}}^{-t/\tau^{(2 ) } } \:,\ ] ] where the correlation lifetime is given by @xmath106 eq . shows that the correlation lifetime drastically grows near the critical point @xmath44 . its maximum value can be estimated from eq . by substituting @xmath107 , which gives the value @xmath108 that is larger than the correlation lifetime in all other regimes by the factor @xmath109 . the dependence of the lifetime @xmath42 on the pumping rate near the critical point @xmath41 is shown in the fig . [ fig : static](d ) by the dash - dotted line . the origin of the peak in the correlation lifetime at @xmath44 can be qualitatively understood as follows . at @xmath110 , the strong coupling regime is already destroyed due to the self - quenching . however , if @xmath111 , the number of photons in the cavity is still large , see eq . . hence , this system can be viewed as a conventional weak - coupled laser , where the fluctuations lifetime is increased due to the bosonic stimulation factor , @xmath112.@xcite for single dot in the cavity such decay time enhancement can be realized only in strong coupling , because in weak coupling case the number of photons remains small at any pumping , see fig . [ fig : static](b ) and sec . [ sec : weak ] below . in the weak coupling regime , @xmath113 . curves are plotted for @xmath76 and various pumping rates @xmath114 . solid lines are obtained from the numerical calculation . dashed lines present moderate pumping case and are plotted after eq . ( [ g2t_weak ] ) . the inset shows the pumping dependence of the correlation lifetime @xmath42 . dashed region corresponds to the unphysical divergence in @xmath42 near @xmath115 when @xmath116 and the lifetime eq . is of no sense . ] in this section we analyze the structures where the strong coupling condition @xmath117 is violated . figures [ fig : static](a)[fig : static](d ) show the dependence of the particle numbers , stationary two - photon correlator and correlation lifetime on the coupling strength . decrease of the coupling strength parameter @xmath109 suppresses the maximal number of photons and peak value of @xmath42 , and also shifts the self - quenching transition to the lower values of pumping ( blue curves in fig . [ fig : static ] ) . as soon as the coupling strength @xmath13 becomes smaller than @xmath16 , the regime of weak coupling between the photon and the exciton is realized . at weak coupling the number of photons is much less than one at any pumping as can be clearly seen from the red curve ( @xmath113 ) in fig . [ fig : static](b ) . smallness of the photon number allows one to consider only the lowest levels of the system when deriving analytical results . hence , we take into account the states with no more than one photon when calculating photon number and dot occupation , and the states with up to two photons for photon - photon correlator . analytical expressions for the particle numbers in the weak coupling regime read@xcite @xmath118}{(w+{\gamma_{\rm c}}+{\gamma_{\rm x}})[4g^2+{\gamma_{\rm c}}(w+{\gamma_{\rm x } } ) ] } \label{nxc_weak}\:,\\ { n_{\rm c}}= \frac{4g^2 w}{(w+{\gamma_{\rm c}}+{\gamma_{\rm x}})[4g^2+{\gamma_{\rm c}}(w+{\gamma_{\rm x } } ) ] } \label{nc_weak}\ : . \nonumber\end{aligned}\ ] ] at low pumping both @xmath74 and @xmath75 grow linearly with pumping . at large pumping the dot is completely populated , @xmath119 , while the cavity is empty ( @xmath120 ) due to the self - quenching effect , see figs . [ fig : static](a ) and [ fig : static](b ) . analytical expression for @xmath3 in the `` bad '' cavity regime ( @xmath121 ) is @xmath122 in the limit of vanishing pumping and @xmath123 the value of @xmath3 is smaller than the strong coupling limit @xmath124 . with decrease of the coupling strength @xmath13 antibunching becomes stronger due to smaller admixture of photons to the exciton state . with increase of the pumping rate the initial value @xmath125 grows from zero ( antibunching ) to @xmath126 ( thermal regime ) , see fig . [ fig : static](c ) . the lasing regime with the plateau at @xmath127 is destroyed in weak coupling case . shown in the figs . [ fig : static](a)[fig : static](c ) by the dashed lines is the analytical dependence plotted after eqs . ( [ nxc_weak ] ) and ( [ g20_weak ] ) . one can see the perfect agreement with the numerical calculation shown by the solid lines . the time dependence @xmath0 is calculated according to the procedure defined by eq . ( [ eq : g2_eq ] ) . for simplicity we neglect the exciton damping @xmath98 and consider only the two limiting cases of pumping low and high as compared to the spontaneous decay rate of the exciton @xmath128 . at low pumping we obtain @xmath129 the system demonstrates antibunching similar to the case of the quantum dot without the cavity . the only effect of the cavity is the enhancement of the exciton decay rate due to the purcell effect . in the opposite case of high pumping , @xmath130 , one gets @xmath131 \:.\end{aligned}\ ] ] we note that eq . ( [ g2t_weak ] ) is finite at @xmath132 and reduces to @xmath133 for this particular value of pumping . in the fig . ( [ weak ] ) the dependence defined by eq . ( [ g2t_weak ] ) is plotted by dashed curves . for the high pumping @xmath94 eq . ( [ g2t_weak ] ) reduces to @xmath134 . this corresponds to low number of cavity photons and thermal statistics . the decay time @xmath42 decreases from @xmath135 to @xmath48 with pumping growth , see fig . [ fig : static](d ) and inset in fig . although the behavior of the decay time in weak coupling is generally monotonous , there is a region of pumping values , where @xmath0 is close to unity , see the wine - colored curve for @xmath136 . in this case the correlation lifetime @xmath42 defined according to eq . is of no sense . thin dotted lines in fig . [ fig : static](d ) and in the inset of fig . [ weak ] correspond to this region . theory of time - resolved second - order correlations of photons , emitted from the incoherently stationary pumped microcavity with single quantum dot has been developed . explicit analytical expressions for the photon number , exciton number , and the photon - photon correlator @xmath0 have been obtained . in the strong coupling regime the correlation function @xmath0 demonstrates decaying in time rabi oscillations . both the frequency and the decay rate of these oscillations increase with growth of the pumping rate . at larger pumping the dynamics of the correlations is monoexponential . the decay time nonmonotonously depends on the pumping and has a sharp peak at the critical pumping value corresponding to the self - quenching transition between lasing regime [ where @xmath86 ] and the thermal regime [ @xmath47 . the peak value strongly exceeds the lifetime of the empty cavity mode . such nonmonotonous behavior of the correlation lifetime is a characteristic feature of the cavity with single dot in the strong coupling regime . in the weak coupling regime the correlation function almost monotonously changes from the initial value at @xmath36 to unity at large delays . the value of zero delay correlator @xmath3 in weak coupling regime is smaller than unity at low pumping ( photon antibunching ) and tends to 2 at large pumping ( thermal bunching ) . the increase of pumping shortens the decay time of the photon - photon correlations . [ [ acknowledgments . ] ] acknowledgments . + + + + + + + + + + + + + + + + the authors acknowledge fruitful discussions with m.m . this work was supported by the rfbr , rf president grants md-2062.2012.2 and nsh-5442.2012.2 , eu projects spangl4q and polaphen , and the `` dynasty '' foundation . in this appendix we present the details of the derivation of the analytical answers eqs . for the stationary density matrix and for the time - dependent two - photon correlator . we focus on the strong coupling regime and moderate pumping @xmath138 . the key simplification in the strong coupling regime is the smallness of the non - diagonal components of the stationary density matrix . this is valid because the energy width of the polariton eigenstates eq . is on the order of @xmath139 and much less than the splitting between these states @xmath87 , where @xmath52 is the relevant rung number of the jaynes - cummings ladder . estimating the typical values of @xmath52 as @xmath114 we obtain the small parameter @xmath140 for the non - diagonal density matrix elements . note , that for sufficiently high pumping @xmath100 this parameter is no longer small . the non - diagonal density matrix elements in this case are given by eq . and their effect is discussed in detail in appendix [ apq ] . thus , in the regime of moderate pumping one can consider the dynamics of the diagonal and non - diagonal density matrix elements separately . the kinetic equation for the diagonal elements @xmath141 , @xmath142 is obtained from liouvillian eq . and reads @xmath143\ : , \nonumber\\ \frac{{{\rm d}}f_0}{{{\rm d}}t } = & -w f_0 + ( { \gamma_{\rm x}}+ { \gamma_{\rm c } } ) f_1\:.\end{aligned}\ ] ] stationary solution of this equation can be found using the fact that the probability flow between the two adjacent rungs @xmath52 and @xmath144 should be zero , i.e. @xmath145 this yields the following probability distribution , @xmath146 that should be normalized according to @xmath147 hereinafter we neglect the exciton damping for simplicity , @xmath98 . in this case ( [ eq : adistrgx ] ) and ( [ eq : adistrnorm ] ) lead to eq . ( [ eq : distr ] ) . stationary photon ( @xmath75 ) and exciton ( @xmath74 ) numbers and the two - photon correlator @xmath3 are readily found from the distribution @xmath148 , @xmath149 which yields eqs . ( [ eq : ng2_strong ] ) . the time dynamics of @xmath0 is governed by eq . ( [ eq : g2_eq ] ) . one needs to determine the time dependence of the operator @xmath150 $ ] . this operator can be separated into diagonal and nondiagonal parts in the basis of polarion eigenstates : @xmath151 , @xmath152 ( diagonal part ) , and @xmath153 ( nondiagonal part ) . these two parts evolve independently in the regime of strong coupling and moderate pumping . correlation function eq . ( [ eq : g2_def ] ) can be expressed through the matrix elements as @xmath154 \:.\ ] ] initial conditions at @xmath36 read @xmath155 below we consider the time dynamics of the diagonal matrix elements first , and then analyze the non - diagonal ones . diagonal elements satisfy eqs . ( [ eq : adiag_eq ] ) where @xmath156 should be replaced with @xmath157 . to determine their time dependence we analyze the eigenvectors and eigenvalues of this linear system . the largest eigenvalue is zero and corresponds to the stationary distribution function @xmath158 . all other eigenvalues are negative and describe the solutions decaying with time . our goal is to provide an estimation for the non - zero eigenvalue with the smallest absolute value @xmath90 . comparison with the numerical calculation demonstrates that this single eigenvalue satisfactory describes the dynamics of the diagonal matrix elements @xmath159 . the lindblad - type matrix , corresponding to the right - hand side of eqs . ( [ eq : adiag_eq ] ) , is not hermitian . the problem can be still reduced to a hermitian one by the procedure adopted for kinetic and fokker - planck equations.@xcite in our case this procedure is formally equivalent to the definition of the scalar product of two distributions @xmath160 and @xmath161 as @xmath162 in terms of the scalar product ( [ eq : scalar ] ) the operator corresponding to right - hand side of eqs . , denoted in what follows by dot , turns out to be self - adjoint , i.e. @xmath163 for any distributions @xmath160 and @xmath161 . this allows one to analyze kinetic eqs . by the standard approaches of quantum mechanics . for instance , the normalization condition eq . assumes the compact form @xmath164 . it is convenient to single out from the considered distribution @xmath157 the stationary contribution @xmath165 , that corresponds to zero eigenvalue . this yields @xmath166 initial conditions for the new variables @xmath167 read @xmath168 since the projection of @xmath169 onto the stationary solution @xmath170 is zero , @xmath171 vanishes at large times , which allows to verify that @xmath172 at @xmath173 . approximating the time decay as @xmath174 and substituting eqs . , into eq . we obtain the first two terms in the right - hand side of eq . . here , @xmath90 is the desired eigenvalue governing the time decay of @xmath175 . it can be estimated using the following variational ansatz for the corresponding eigenvector @xmath176 the constant @xmath177 is found by imposing the orthogonality condition @xmath178 . once @xmath177 is found , the value of @xmath90 is given by @xmath179 the result of calculations reduces to eq . . now we turn to the evolution of the nondiagonal matrix elements @xmath180 . in the strong coupling regime this procedure is quite simple . one can assume that each matrix element @xmath181 oscillates in time with its own frequency @xmath182 and decays exponentially . the intermixing of different rungs can be neglected provided that the frequency difference between the adjacent rungs @xmath183 is smaller than the coupling term , which is on the order of the pumping strength @xmath14 . this is realized for @xmath184 , i.e. below the transition to the lasing regime . @xcite note that in the polariton lasing regime @xmath86 [ see eq . ( [ eq : ng2_strong ] ) ] , and the photon correlator dynamics is trivial , @xmath185 . therefore this case does not need any special consideration . hence , the desired time dependence of @xmath186 is described as @xmath187t}\:.\ ] ] substituting the non - diagonal component dynamics defined by eq . ( [ eq : and_t ] ) into eq . ( [ ag_chi ] ) we recover the last term in eq . ( [ eq : g2t_strong ] ) . in this appendix we present the details of the @xmath0 correlator dynamics for the system in strong coupling regime and under high pumping . we focus on the transition from lasing to self - quenching regime ( @xmath99 ) when the correlation lifetime turns out to be extremely long . despite the strong coupling , sufficiently high pumping leads to the intermixing of the hamiltonian eq . eigenstates . therefore the density matrix is no more diagonal in the polariton basis . inside the @xmath52-th rung of jaynes - cummings ladder it can be written as @xmath188 in the basis of eigenstates eq . . the liouvillian does not mix the intra - rung and inter - rung density matrix components . thus , the stationary density matrix , as well as the operator @xmath189 that describes @xmath0 dynamics , do not contain inter - rung components . in the considered regime of high pumping the density matrix equations for the rung @xmath52 read @xmath190 \nonumber\\ & + { \gamma_{\rm c}}[(m+1/2)f_{m+1 } - ( m-1/2)f_{m } ] \:,\nonumber\\ \frac{{{\rm d}}x_m}{{{\rm d}}t } & = -2{{\rm i}}\sqrt{m } g x_m - w(f_m + 3x_m/4 + x_m^*/4 ) \:.\end{aligned}\ ] ] the diagonal components @xmath156 change with the rate of the order of @xmath16 , as will be proven later . the non - diagonal component @xmath191 relaxes to its quasi - stationary value with much larger rate on the order of @xmath14 . hence , we assume that @xmath191 adiabatically follows diagonal components @xmath156 , i.e. @xmath192 after substitution of the expression eq . for the non - diagonal components into eq . we obtain @xmath193\:,\label{eq : fq}\end{aligned}\ ] ] where @xmath194 and @xmath195 . in moderate pumping case @xmath196 is close to unity and eq . reduces to eq . . since we consider high rungs we can replace discrete rung number @xmath52 with continuous variable , which yields @xmath197 \nonumber\:,\end{aligned}\ ] ] where @xmath198 is the probability current . the stationary solution found from the condition @xmath199 reads @xmath200 with the growth of the pumping the maximum of the stationary distribution function eq . behaves as @xmath201 . it grows linearly at low pumping , reaches maximum at @xmath202 , then decreases , reaches zero at critical pumping value @xmath203 when @xmath204 , and remains zero for higher pumping . first we consider the subcritical pumping , @xmath205 . the stationary distribution function eq . in this case can be approximated as gaussian , @xmath206 \:.\ ] ] we use the distribution function eq . for @xmath207 to calculate @xmath74 , @xmath75 , and @xmath3 according to eqs . and and taking into account both diagonal and non - diagonal components of the stationary density matrix eq . this yields the results presented in the upper parts of eqs . . time - dependent eq . reduces to @xmath208 \:,\ ] ] where @xmath209 is the mean rung number . dynamics of the correlator @xmath0 according to eq . is given by @xmath210 where @xmath211 satisfies dynamic equation with initial condition @xmath212 . this initial condition can be presented as a sum of two contributions : @xmath213 and @xmath214 . the first one does not evolve with time and provides the correct limit @xmath215 at @xmath216 , while the latter turns out to be the eigenfunction of the right - hand side of eq . with the eigenvalue @xmath217 . hence , this eigenvalue describes the decay of the correlator @xmath0 to unity , given in eq . and upper part of eq . . in the opposite case of the pumping rate larger than the critical @xmath207 ( @xmath110 ) the stationary distribution function eq . reduces to thermal one , @xmath218 where now the mean rung number is given by @xmath219 . using distribution function eq . we calculate the analytic expressions for @xmath74 and @xmath75 presented in the lower parts of eqs . . however , in order to get a correction to @xmath220 it is indispensable to take into account a deviation of the static distribution from thermal . this can be done by introducing a factor @xmath221 into eq . . dynamic equation for the pumping higher than critical reduces to @xmath222 \:.\ ] ] one can easily check that @xmath223 is again the eigenfunction of the right - hand side of eq . . thus , the decay of the correlator @xmath0 is governed by the corresponding rate @xmath224 , which leads to eq . and the lower part of eq . . 34ifxundefined [ 1 ] ifx#1 ifnum [ 1 ] # 1firstoftwo secondoftwo ifx [ 1 ] # 1firstoftwo secondoftwo `` `` # 1''''@noop [ 0]secondoftwosanitize@url [ 0 ] + 12$12 & 12#1212_12%12@startlink[1]@endlink[0]@bib@innerbibempty @noop _ _ ( , , ) link:\doibase 10.1103/physrevlett.103.217402 [ * * , ( ) ] link:\doibase 10.1038/nature09148 [ * * , ( ) ] link:\doibase 10.1080/00107511003602990 [ * * , ( ) ] @noop _ _ ( , , ) link:\doibase 10.1038/35023100 [ * * , ( ) ] link:\doibase 10.1126/science.1066790 [ * * , ( ) ] link:\doibase 10.1103/physrevlett.106.227402 [ * * , ( ) ] link:\doibase 10.1103/physrevb.86.115330 [ * * , ( ) ] link:\doibase 10.1038/nphys227 [ * * , ( ) ] @noop * * , ( ) link:\doibase 10.1038/nphys1518 [ * * , ( ) ] link:\doibase 10.1038/nphoton.2010.286 [ * * , ( ) ] link:\doibase 10.1103/physrevlett.39.691 [ * * , ( ) ] link:\doibase 10.1038/280451a0 [ * * , ( ) ] link:\doibase 10.1103/physrevlett.94.053604 [ * * , ( ) ] http://stacks.iop.org/0253-6102/56/i=1/a=23 [ * * , ( ) ] link:\doibase 10.1103/physrevb.79.235326 [ * * , ( ) ] link:\doibase 10.1103/physreva.84.043816 [ * * , ( ) ] link:\doibase 10.1063/1.3689782 [ * * , ( ) ] link:\doibase 10.1103/physrevb.85.075311 [ * * , ( ) ] link:\doibase 10.1103/physrevb.86.115326 [ * * , ( ) ] link:\doibase 10.1103/physrevb.81.121310 [ * * , ( ) ] link:\doibase 10.1134/s1063776109050124 [ * * , ( ) ] @noop * * , ( ) link:\doibase 10.1103/physrevb.82.205330 [ * * , ( ) ] link:\doibase 10.1103/physrevlett.109.183601 [ * * , ( ) ] link:\doibase 10.1103/physreva.46.5944 [ * * , ( ) ] @noop * * , ( ) link:\doibase 10.1088/0022 - 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the time dependence of the correlations between the photons , emitted from the microcavity with embedded quantum dot under incoherent pumping , is studied theoretically . analytical expressions for the second - order correlation function @xmath0 are presented in strong and weak coupling regimes . at moderate pumping the correlation function demonstrates rabi oscillations , while at larger pumping it shows monoexponential decay . the decay time of the correlations nonmonotonously depends on the pumping value and has a maximum corresponding to the self - quenching transition .

magnetic fields can profoundly affect the properties of the intergalactic medium in clusters . examples include suppression of heat conduction , which is required to maintain the cluster cooling flows ( see the review by fabian 1994 ) , and a possibility of a dynamically significant magnetic pressure to explain the difference between the x - ray and strong lensing cluster mass estimates ( loeb & mao 1994 , miralda - escud & babul 1995 ) . so far , intracluster magnetic fields were measured by faraday rotation in radio sources seen through the igm ( e.g. , kim , kronberg & tribble 1991 ) , or by combining radio and hard x - ray data on cluster radio halos under the assumption that the x - rays ares produced by inverse compton scattering of the microwave background ( e.g. , fusco - femiano et al . both these methods indicate the magnetic field strength on the microgauss level , with considerable uncertainty . in this paper , we apply a completely new approach that uses the effect of the magnetic field on the dynamics of the intracluster plasma . _ chandra _ recently revealed that in at least two clusters , a2142 ( markevitch et al . 2000 ) and a3667 ( vikhlinin , markevitch & murray 2000 , paper i hereafter ) , the dense cool cores are moving with high velocity through the hotter , less dense surrounding gas . in both cases , the cool gas is separated from the hotter ambient gas by a sharp density discontinuity , or a `` cold front '' . a similar structure appears to be observed in rxj1720.1 + 2638 ( mazzotta et al . 2000 ) , although the temperature data for that cluster are less accurate . in paper i , we have shown that the cool gas cloud in a3667 moves with a near - sonic velocity in the ambient hot gas . while the speed of the cloud in a2142 can not be measured accurately , its value is consistent with velocities up to the velocity of sound . a strong suppression of the transport processes , most probably by magnetic fields , is required to prevent the observed sharp density and temperature gradients from dissipating . ettori & fabin ( 2000 ) argue that the sharp change of gas temperature in a2142 requires a very significant suppression of heat conduction relative to the classical value . in a3667 , the suppression of diffusion is observed directly , because the width of the density discontinuity is smaller than the coulomb mean free path ( paper i ) . in both a3667 and a2142 , the cold front appears to be dynamically stable because it has a smooth shape and shows no visible perturbations within a certain sector in the apparent direction of the cloud motion . in this paper , we use this fact to infer the strength of the intracluster magnetic field that could naturally provide surface tension stabilizing the front against the development of the kelvin - helmholtz instability . we use @xmath2 km s@xmath3 mpc@xmath3 . the derived magnetic field strength scales as @xmath4 , while the derived ratio of magnetic and thermal pressures does not depend on @xmath5 . the full account of the _ chandra _ observation of a3667 is given in paper i , and here we briefly review the relevant details . the most prominent feature in the _ chandra _ image is the sharp 0.5 mpc - long discontinuity in the surface brightness distribution located approximately 550 kpc south - east of the cluster center ( fig . [ fig : edge ] ) . the gas temperature distribution shows unambiguously that this structure is a boundary between the large dense body of cool ( @xmath6 kev , 68% confidence ) gas moving through the hotter ( @xmath7 kev ) ambient gas . we call this structure the `` cold front '' . the front shape in projection is very accurately described by a circle with @xmath8 kpc . the gas pressure profile across the front shows that the cloud moves at a speed close to the velocity of sound in the ambient hot gas ( with the mach number @xmath9 ) . the measured high velocity of the cloud is substantiated by the observed compression of the ambient gas near the front , and a possible bow shock seen in the _ chandra _ image further ahead of the front . this moving cloud probably is a remnant of one of the large subclusters that have merged recently to form the a3667 cluster . the observed width of the front is very small . even with the _ chandra _ resolution , the surface brightness profile across the front is consistent with projection of an infinitely narrow gas density discontinuity . the upper limit on its width , @xmath10 or @xmath11 kpc , is 23 times smaller than the coulomb mean free path ( paper i ) . this requires suppression of the diffusion by a magnetic field . a magnetic configuration which can stop the diffusion should indeed arise in a narrow boundary region between the two tangentially moving gas layers , through a process schematically shown in fig . [ fig : mag ] . as the ambient gas flows around the dense cloud and the cool gas is stripped from the surface of the cloud , magnetic field lines , which are frozen into the gas and initially tangled , should stretch along the front . when a layer with the parallel magnetic field forms , it would prevent further stripping of the cool gas and also stop microscopic transport processes across the boundary , explaining the observed small width of the front . such a layer with the parallel magnetic field also would support the dynamical stability of the front . at some distance from the leading edge of the cloud , the gas exterior to the front should develop a high tangential velocity . the interface between the tangentially moving gas layers normally is unstable due to the kelvin - helmholtz ( k - h ) instability . we show below that in the absence of any stabilizing factors , the k - h instability should disturb the front surface outside @xmath12 of the direction of the cloud motion . figure [ fig : edge ] shows that the front has a smooth circular shape and remains sharp within the sector @xmath13 in the direction of motion , and hence should be dynamically stable . we suggest that the k - h instability is suppressed by surface tension of the frozen - in magnetic field , provided that it is parallel to the front . at larger angles ( @xmath14 ) from the direction of motion , the front becomes less sharp and gradually vanishes . we interpret this as the onset of the k - h instability , when the tangential velocity of the ambient gas exceeds a critical value beyond which the instability can not be suppressed by the magnetic field ( cf . [ fig : mag]b ) . assuming that the interface between two gases is barely unstable at @xmath15 , we can estimate the required magnetic field strength . our further discussion is organized as follows . in [ sec : tang : velocity ] , we estimate the distribution of the tangential velocity of the ambient gas near the leading edge of the cloud . in [ sec : kh : hydro ] , we demonstrate that if the kelvin - helmholtz instability is not suppressed , its growth time is smaller than the cluster core passage time for angles @xmath16 , and therefore the instability already should have disturbed the front . in [ sec : kh : suppression ] , we estimate the magnetic field strength from the condition that the kelvin - helmholtz instability is suppressed within the sector @xmath17 , but develops at larger angles . for simplicity , we assume that the front moves through the ambient gas with the mach number @xmath18 exactly ( while the measured value is @xmath9 ) . for our purposes , the 3d shape of the cloud can be approximated by a cylinder with a @xmath19 kpc radius that has a rounded head with the curvature radius @xmath20 kpc seen as a front in projection . the radius of the region of interest ( an area on the front within @xmath21 ) is smaller than the radius of the cylinder . therefore , we can adequately approximate the gas flow in this region by that around a ( @xmath20 kpc ) sphere , for which there are published laboratory measurements and numerical simulations for a range of mach numbers of the inflowing gas . it is instructive to consider first the analytic solution for the flow of an incompressible fluid ( e.g. , lamb 1945 , see also fig . [ fig : mag]b ) . the inflowing gas slows down near the stagnation point at the leading edge of the sphere but then reaccelerates to high velocities as it is squeezed to the sides by new portions of the inflowing gas . the velocity at the surface of the sphere has only a tangential component , @xmath22 , where @xmath23 is the velocity of the inflowing gas at infinity . already at @xmath15 , the incompressible gas has @xmath24 . there is no known analytic solutions for the flow of compressible gas around a sphere at @xmath25 , but the qualitative picture is similar . we use the results of numerical simulations of the @xmath26 flow by rizzi ( 1980 ) , whose results are in good agreement with the published laboratory measurements at slightly higher @xmath27 ( e.g. , gooderman & wood 1950 ) . the velocity field of a compressible gas flow is parameterized by the spatial distribution of the local mach number . the distribution of the mach number on the surface of the sphere derived from rizzi s simulation can be approximated as @xmath28 at @xmath15 , the local mach number is @xmath29 . in absolute units , the gas velocity at this point is @xmath30 , i.e. only 20% lower than that in the incompressible solution . consider the flat interface between cold gas at rest and a hotter gas flowing at the local mach number @xmath31 . the velocity of the flow can be sufficiently large so that the compressibility of the gas is important . in the absence of stabilizing factors such as gravity or surface tension , the interface is unstable due to the kelvin - helmholtz instability ( see , e.g. , gerwin 1968 for a review ) . the wave vector of the fastest - growing mode is in the direction of the flow . the growth time of this mode can be found from the dispersion equation ( cf . eq . 5.5 in miles 1958 ) : @xmath32 where @xmath33 and @xmath34 are the velocities of sound in the cold and hot gas , respectively , and @xmath35 and @xmath36 is the wave number and frequency . in solving this equation , we should take into account the adiabatic compression of the hot gas as it arrives at the surface of the cold cloud from infinity , where it flows at our measured mach number @xmath37 . the velocity of sound as a function of the local mach number is ( e.g. , landau & lifshitz 1959 ) @xmath38 where @xmath39 is the velocity of sound in the inflowing gas at infinity , @xmath40 for the actual temperatures inside and outside our cloud ( [ sec : observations ] ) , and @xmath41 is the adiabatic index . for plausible values of @xmath31 , equation ( [ eq : dispers ] ) has two complex roots , one of which corresponds to the growing mode . the instability growth time is @xmath42 . perturbations of all scales are unstable , but for some scales , the instability may develop slowly compared to the lifetime of the front . the relevant time scale with which @xmath43 should be compared is the cluster core passage time , @xmath44 , where @xmath45 is the cluster size . the value of @xmath46 is the perturbation growth factor over the period of time it takes the cool gas cloud to travel the distance @xmath45 ; if @xmath47 , the perturbation is effectively unstable . for the observed gas temperatures and @xmath48 , the numerical solution of eq . ( [ eq : dispers ] ) for @xmath49 , the regime relevant for our region of interest , gives the approximate relation @xmath50 , where @xmath51 is the perturbation wavelength . combining this with the distribution of the mach number on the surface of the sphere ( eq . [ eq : rizzi : m ] ) , we have @xmath52 for a cluster - scale length of @xmath53 mpc , we find that a 10 kpc perturbation becomes effectively unstable already for @xmath54 . at @xmath15 , perturbations with @xmath55 kpc are unstable . however , the front appears undisturbed within at least 30 around the direction of motion . recall that the observed width of the front is smaller than 5 kpc , and a 45 kpc widening would be easily observable . therefore , the k - h instability of the cold front must be suppressed . long - wavelength k - h perturbations can be stabilized by a gravitational field perpendicular to the interface ( e.g. , lamb 1945 ) . however , we find that for the gravitational acceleration estimated from the gas pressure gradient outside the cloud , only @xmath56 kpc modes are stable , and therefore gravity is unimportant for the wavelengths of interest . the k - h instability can be suppressed by the surface tension of a magnetic field , if the magnetic field is parallel to the interface and to the direction of the flow . our considerations can be greatly simplified by the fact that the gas can be treated as incompressible on both sides of the cold front in the region of interest , @xmath21 . the outer gas can be considered incompressible because it flows with a relatively low local mach number @xmath57 . the cool gas can be considered incompressible because the growing modes of the k - h instability generally have low phase speed . indeed , the solution of eq . ( [ eq : dispers ] ) obtained above is very close to the solution in the incompressible limit @xmath58 for the gas velocities of interest . the interface between the two incompressible magnetized fluids is stable if @xmath59 where @xmath60 and @xmath61 is the magnetic field strength in the hot and cool gas , @xmath62 and @xmath63 are the gas densities , and @xmath64 is tangential velocity of the hot gas ( e.g. , landau & lifshitz 1960 , if the magnetic pressure is small compared to the thermal pressure , @xmath65 ( as it turns out to be the case ) , or is the same fraction of @xmath65 on both sides of the interface , the stability condition ( [ eq : kh : mag ] ) can be rewritten in terms of the thermal pressure and temperature of the gas : @xmath66 the stability of the cold front within @xmath67 of the direction of the cloud motion , where @xmath68 , requires @xmath69 for the observed ratio of @xmath70 . if smearing of the surface brightness edge at angles @xmath71 is interpreted as the development of the k - hinstability , this lower limit becomes a measurement of the magnetic pressure . if magnetic field is too weak to suppress the k - h instabilty completely , it still increases the instability growth time , which is then @xmath72^{-1/2}.\ ] ] thus , even with a weaker magnetic field , the interface can be effectively stable on the time scale of the cluster core passage . however , eq . ( [ eq : kh : mag : growth ] ) shows that this quickly becomes unimportant as the magnetic field strength decreases below the stability limit . for example , for @xmath73 of only 0.70.8 of the stability limit , the growth time is 1.11.4 of its value for @xmath74 . the measurement uncertainty in the derived value of the magnetic field strength is mostly due to uncertainty in the angle , @xmath75 , where the interface becomes unstable , and hence in the local mach number of the hot gas . for @xmath75 in the range @xmath76 ( which appears to be a conservative interval , see fig . [ fig : edge ] ) , we find from eq . ( [ eq : kh : mag ] ) and ( [ eq : rizzi : m ] ) that the magnetic field strengths are in the interval @xmath77 our method directly constrains only the sum of magnetic pressures on the two sides of the interface . the maximum of the magnetic field strengths in the cold and hot gases , @xmath78 , is in the interval @xmath79 , where @xmath80 is constrained by ( [ eq : pmag : contsraint ] ) . using the value of gas pressure inside the dense cloud derived in paper i , we find the corresponding uncertainty interval @xmath81 . we showed that the sharpness of the front at small angles from the direction of the cloud motion and its smearing at larger angles can be explained by the existence of a layer in which the magnetic field is roughly parallel to the front and has a strength of order @xmath82 . as we discussed above , such a layer may form by stretching the magnetic field lines near the front by tangential gas motions . as a result , the magnetic field strength in this layer is probably higher than in the rest of the intracluster gas . the magnetic field amplification on the surface of the plasma cloud is discussed , for example , in jones , ryu & tregillis ( 1996 ) . an important conclusion is that the magnetic pressure is only a small fraction of the thermal pressure : @xmath83 in the magnetic layer and still lower in the rest of the cluster . if the magnetic pressure were of order of the thermal pressure , the front would be stable for mach numbers up to @xmath84 , i.e. over the entire surface of the cool gas cloud . faraday rotation measurements of the magnetic field outside the cluster cooling flows usually give the values of @xmath85 ( kim et al . since faraday rotation gives the integral of the magnetic field along the line of sight , there is a considerable uncertainty of the absolute field strength due to unknown degree of entanglement . near the cold front , the field is straightened and amplified , so our measurement provides a likely upper limit on the absolute field strength in the cluster core . finally , we note that our arguments would become invalid if the shape of the front were non - stationary , for example , if the cool gas cloud expands into the low - density medium ( as opposed to moving as a whole ) . however , the front velocity relative to the ambient gas exceeds the velocity of sound within the cloud . since the _ in situ _ acceleration of a gas cloud to the supersonic velocity is impossible , the cool gas cloud must have arrived from outside the main cluster . in this case , the fact that the shape of the front remains smooth and circular after traveling a large distance , suggests that the front is in fact close to stationary , and therefore our arguments regarding the magnetic field are valid .

we use the _ chandra _ observation of the cold front in the intracluster gas of a3667 to estimate the magnetic field strength near the front . the front is seen in the _ chandra _ data as a sharp discontinuity in the gas density which delineates a large body of dense cool gas moving with the near - sonic velocity through the less dense , hotter gas . without a magnetic field , the front should be quickly disturbed by the kelvin - helmholtz instability arising from tangential motion of gas layers . however , _ chandra _ image shows that the front is stable within a @xmath0 sector in the direction of the cloud motion , beyond which it gradually disappears . we suggest that the kelvin - helmholtz instability within the @xmath0 sector is suppressed by surface tension of the magnetic field whose field lines are parallel to the front . the required field strength is @xmath1 . magnetic field near the front is expected to be stronger and have very different structure compared to the bulk of the intergalactic medium , because the field lines are stretched by the tangential gas motions . such a magnetic configuration , once formed , would effectively stop the plasma diffusion and heat conduction across the front , and may inhibit gas mixing during the subcluster merger . we note that even the increased magnetic field near the front contributes only 1020% to the total gas pressure , and therefore magnetic pressure is unimportant for hydrostatic cluster mass estimates .

a 54 year - old man was referred to the outpatient clinic having been injured in his right eye by the hook of a clothes hanger while falling . swelling and bruising on the right eyelid he complained of image tilting in the right eye compared to the image inthe left eye . non - dilatating fundusphotos ( vx-10 ; kowa optimed , tokyo , japan ) showed a 12-degree excyclotorsion in the right eye and an 8-degree excyclotorsion in the left eye . image j ( national institutes of health , bethesda , md , usa ) was used to measure the angle between the line that crosses the center of the optic disc and parallels the fovea and the line that extends from the optic disc center to the fovea . non - enhanced orbit computed tomography was performed to rule out eyeball rupture , intraocular foreign body , or orbit wall fracture as well as any other abnormalities . during surgery , a 15-mm horizontal conjunctival laceration over the superior rectus muscle was found . the tendon of the superior oblique muscle protruded inferio - nasally through the lacerated conjunctiva ( fig . the cut margin of the ruptured tendon was irregular and the width was about 4 mm . it was assumed that the location of the rupture was in the middle of the tendon under the superior rectus muscle . the superior rectus muscle seemed to be intact . to correct torsional diplopia , we attached the anterior and posterior borders of the superior oblique tendon 5 and 9 mm apart from the nasal margin of the superior rectus muscle insertion ( fig . one week postoperatively , the patient showed vertical diplopia and 4-prism dioptor right hypertropia by the alternative prism and cover test in the primary position . however , the patient did not complain of torsional diplopia . in the fundus photographs , three months postoperatively , right hypertropia gradually increased to 20-prism diopters and the patient complained of vertical diplopia . it loops through the trochlea , and passes under the superior rectus muscle and inserts into the sclera on the posterotemporal surface of the eyeball . traumatic injury to the superior oblique muscle is extremely rare , and mostly arises from injuries caused by hook - shaped objects , and is frequently associated with penetrating eyelid injury . when the ruptured muscle belly from the origin could not be found and was left unconnected , the patient showed a pattern of superior oblique muscle palsy . however , harish et al . reported that excision of the loose hanging tendon near the medial border of the superior rectus muscle did not result in progressive muscle sequelae until six months later . that might be possible because some of the posterior fibers of the superior oblique tendon were still intact . in our case , the patient initially complained of torsional diplopia , which coincided with the excyclotorsion of the right eye on the fundus photograph . to correct this , we planned to reattach the ruptured tendon to the middle of the original track where the superior oblique muscle might have passed . dow found that anchoring the avulsed superior oblique muscle to the medial orbital wall adjacent to the trochlea resulted in slight hypertropia with full ocular motility . however , when the ruptured tendons were reapproximated with each other , postoperatively , asymptomatic brown 's syndrome could develop . because the ruptured superior oblique muscle shortened in our case , we recessed the muscle 5 mm from the medial border of the superior rectus muscle . according to parks and helveston , the distance between the nasal edge of the superior rectus and anterior border of the superior oblique muscle in the primary position was 3 to 5 mm . torsional diplopia , the main complaint of the patient , improved and the degree of excyclotorsion of the right eye decreased in the fundus photographs . however , three months after the operation , hypertropia increased to 20 prism dioptors . this could have been due to the torn tendon that was not attached far enough laterally to avoid a weakening effect . additionally , during the exploratory procedure to find the distal remnant of the superior oblique tendon , the superior rectus muscle could have been injured , although initially the superior rectus muscle seemed to be intact . upon healing , it might have undergone localized fibrosis that caused contraction and secondary hypertropia . to correct the hypertropia an inferior rectus resection was chosen for adhesion around the superior rectus muscle and to avoid contralateral inferior rectus recession . two months after the second operation , the patient was comfortable and muscle function was stable . when the superior oblique muscle is ruptured , intraoperative reapproximation of the muscle can be performed . however , because the function of the muscle is hard to restore perfectly , postoperative complications should be anticipated and careful follow - up is needed to determine further treatment .

traumatic rupture of the superior oblique muscle is rare . we report a case of a 54-year - old man injured by the metal hook of a hanger , resulting in a rupture of the superior oblique muscle tendon . he complained of torsional diplopia when in the primary position . the distal margin of the superior oblique muscle was reattached to sclera 5 and 9 mm apart from the medial insertion of the superior rectus muscle . one week after the operation , torsional diplopia disappeared . however , a 4-prism diopter ipsilateral hypertropia was observed . three months later , hypertropia gradually increased to 20 prism dioptors and the second operation was done to correct vertical diplopia .

carbon nanotubes ( cnts ) are outstanding examples of one - dimensional ( 1d ) conductors @xcite . when embedded into a circuit and connected to external leads via tunneling barriers , cnts behave as quantum dots @xcite . owing to their one - dimensional nature , their behaviour can be well described by means of a luttinger liquid ( ll ) model @xcite which can also include electron - electron interactions . the latter can lead to several interesting effects , including the formation of wigner molecules @xcite , peculiar correlated electron states characterized by unusual transport properties @xcite which in a cnt can be either probed by means of an atomic force microscope ( afm ) @xcite or the tip of a scanning tunnel microscope ( stm ) @xcite . + among the most prominent applications of cnts is their use as mass @xcite or gas nanoscale sensors @xcite . seminal work on gas sensing using cnt detectors included the study of the change in resistance of single wall nanotubes @xcite or mats of multiwall cnts exposed to an environment containing h@xmath0 or nh@xmath1 molecules @xcite . the ultimate goal of cnt - based nano - sensing is to achieve the resolution of few molecules and to be able to identify the chemical species of the molecule itself . one of the possible `` fingerprints '' of a molecule is its vibrational spectrum . + molecules exhibit several different vibrational modes , with a broad spectrum of vibrational frequencies . the _ intrinsic _ vibrational modes strongly depend on the molecule mass as well as its spatial orientation and on the nature of the chemical bonds composing it . the typical frequency of these modes can be as high as 100 thz ( 65 mev ) @xcite . molecules coupled to a surface , such as the one of the cnt , show additional _ libration _ vibrational modes involving the _ center of mass _ of the molecule itself which oscillates as a whole with respect to the surface @xcite . such modes are much softer , with a vibrational frequency of the order of 1 thz and excitation energies _ smaller _ than 1 mev . + molecular vibrations are typically detected with optical methods such as raman scattering @xcite . however , it is in principle possible to employ the transport properties of a cnt also to detect at least some of these vibrational modes . low - energy modes have excitation energies smaller than the the typical level spacing @xmath2 of a cnt which , for a lentgh @xmath3 can be estimated as @xmath4 mev ( @xmath5 the cnt fermi velocity ) . this allows to single out their signatures in the transport properties , in contrast with the internal vibration modes with excitation energies well exceeding @xmath2 , whose signatures are intertwined with those due to the electronic degrees of freedom of the cnt . in turns , this would lead to `` smart '' molecular sensors , able to detect the presence and the type of molecule attached to it . + this coupling of molecular vibrations and electronic states in a cnt is strongly reminescent of the situation occurring in a nano - electromechanical system ( nems ) @xcite , in which mechanical and electronic degrees of freedom are strongly coupled . suspended carbon nanotubes themselves can behave as nems when current flowing through them excites their vibrational modes @xcite . + another powerful tool to detect the excitation spectrum of a mesoscopic system is the thermopower @xcite . in the context of quantum dots , thermopower has been studied theoretically @xcite as well as experimentally @xcite . it constitutes a powerful tool to investigate the spectrum of excited states of quantum dots in the _ linear regime _ @xcite , in contrast with the more conventional nonlinear transport spectroscopy . in the context of nems , the thermopower has been shown experimentally to provide a way to investigate mechanical vibrations in sequential as well as in the cotunneling regime @xcite . the information brought by thermopower has been employed in the study of molecular junctions @xcite , in the presence of an stm tip @xcite , and even in gas sensors based on cnt mats @xcite . + in this paper we study the behaviour of a single - wall cnt capacitively coupled to a vibrating molecule . the cnt - molecule system is coupled via tunnel barriers to a lateral contact and to a stm tip free to scan the cnt length . focusing on the linear regime , we evaluate the linear charge , the thermal conductance and the thermopower . our task is to investigate to which extent the linear transport properties bring about information about the molecule attached to the cnt surface . our main reults are the following + 1 . the capacitive coupling of the electrons and the molecule leads to the appearance of _ space - dependent _ @xcite franck - condon ( fc ) factors @xcite , whose behaviour is dominated by an effective , space - dependent cnt - molecule coupling constant @xmath6 ( @xmath7 the coordinate of the tip ) which affects the tunneling rate through the tip and the lateral contact . such a coupling constant is peaked around the position where the molecule sits ; + 2 . the linear conductance exhibits a maximum following a simple analytical function of @xmath6 , allowing to identify where the molecule is by scanning the stm tip ; + 3 . the thermopower shows resonant features at energies corresponding to the vibrational spectrum of the molecule , allowing a precise characterization of the latter . + our findings show that thermopower measurements would be able to detect the position of a molecule and to gain information about its vibrational frequency . + the outline of the paper is as follows . in sec . [ sec : sec1 ] the model for the cnt capacitively coupled to the molecule is described and its spectrum diagonalized . in sec . [ sec : sec2 ] a model for the coupled system is introduced and its hamiltonian is exactly diagonalized by means of a canonical transformation . the setup for a transport experiment is then presented , tunneling rates in the sequential regime are evaluated and a master equation is set - up . finally , linear charge and thermal conductances are obtained . section [ sec : sec3 ] contains the results concerning the position - dependent coupling constant , linear conductance and thermopower . finally , in sec . [ sec : sec4 ] we summarize our conclusions . to a molecule vibrating along its libration mode.,width=377 ] the device consists of a single - wall metallic cnt bounded in @xmath8 and @xmath9 , capacitively coupled to a molecule which vibrates around the position @xmath10 . the system is schematically depicted in fig . [ fig : fig1 ] . in the following we will concentrate on the libration modes of the molecule , since their excitation energy compares favorably with the energy scale at which transport experiments are performed . + the hamiltonians of the decoupled cnt and vibrating molecule are respectively ( @xmath11 ) @xmath12\ , , \label{eq : h0cnt}\\ h^{(0)}_{mol}&=&{\frac{\mathbf{p}^{2}}{2m}+\mathcal{u}(\mathbf{r})}\ , , \label{eq : h0molpre}\end{aligned}\ ] ] where @xmath13 and @xmath14 and we neglect the motion of the molecule along the waist of the nanotube , i.e. we assume that the molecule fingerprint is larger than the cnt transverse dimension @xmath15 . here , @xmath16 denotes a radial coordinate perpendicular to the cnt axis . + equation ( [ eq : h0cnt ] ) represents the bosonized hamiltonian of the cnt within the ll language @xcite . it is composed of four sectors @xmath17 where @xmath18 ( @xmath19 ) represent the total charge ( spin ) modes and @xmath20 ( @xmath21 ) represent the relative charge ( spin ) ones . the first term represents the contribution of the cnt zero modes , with @xmath22 the number of extra electrons per sector with respect to a neutral reference situation with @xmath23 electrons . in the following , for definiteness , we assume @xmath23 to be a multiple of four and that each sector @xmath24 thus contains @xmath25 electrons . we have introduced @xmath26 with @xmath27 the propagation velocity of the mode @xmath24 and @xmath28 the ll interaction parameters , which capture the effects of short - range forward scattering among the electrons . one has @xmath29 with @xmath30 for noninteracting electrons . all other parameters @xmath31 due to symmetries of the model @xcite . the second term represents _ collective _ excitations of bosonic character , with spectrum @xmath32 with @xmath33 the quantized momentum ( @xmath34 an integer ) and canonical bosonic operators @xmath35 . + [ fig : fig2 ] the molecule sits in a potential well which , we assume separable @xmath36 . the shape of @xmath37 and @xmath38 is schematically depicted in fig . [ fig : fig2 ] . the molecule is located around the position @xmath10 , corresponding to the minimum of @xmath37 . a rather shallow well is expected , which can be very well approximated by a harmonic potential @xmath39 . concerning the @xmath16 direction , the molecule occupies the minimum of a potential well constituted by a repulsive short - range part and an attractive long range tail . such well , located at a position @xmath40 , is in general much narrower than the one which develops along the @xmath41 direction @xcite . as a consequence , vibrations in the transverse , @xmath16 direction have typical frequencies @xmath42 . in this work , we concentrate on linear transport properties and low temperatures @xmath43 , so that the motion in the @xmath16 direction is effectively `` frozen '' in the ground state of @xmath38 . therefore , upon a redefinition of the zero of energies , the hamiltonian of the molecule simplifies as @xmath44 the molecular vibrations around @xmath10 are thus described by a simple harmonic oscillator in eq . ( [ eq : h0mol ] ) , with @xmath45 the molecule mass , @xmath46 the fluctuating position of the molecule and @xmath47 , @xmath48 the molecule displacement and momentum operators respectively . here and in the following , we will consider the case of vibration frequencies @xmath49 with @xmath50 the molecule and the cnt are assumed to be electrostatically coupled via the term @xmath51 where @xmath52 represents the coupling potential and @xmath53 the total cnt electron density . in this work , we neglect charge tunneling between the cnt and the molecule , which may be the subject of future investigations . we assume that the molecule is physisorbed to the cnt , neglecting chemisorption effects which may induce structural modifications of the local nature of chemical bonds @xcite . + here , @xmath52 represents the electrostatic potential induced on the cnt conduction electrons by the molecule charge cloud . as a model , we choose a finite - range screened potential @xmath54 with @xmath55 describing the amplitude of the potential and @xmath56 the interaction range . it must be stressed however that all the results presented in this paper do not depend qualitatively on the particular choice of @xmath52 as long as it is peaked with a width of the order @xmath56 . assuming vibrations of _ small _ amplitude , we expand eq . ( [ eq : coupl1 ] ) to lowest order and obtain @xmath57 the electron density can be decomposed as the sum of terms @xmath58 , representing the long - wave term ( @xmath59 ) and spatially oscillating contributions with wavelengths @xmath60 with @xmath61 the cnt fermi momentum . for @xmath62 one has friedel oscillations , due to finite - size effects @xcite . terms with @xmath63 are induced for instance by electron - electron correlations , band curvature effects or scattering with impurities which may lead to the formation of a wigner molecule @xcite . in typical cnt sensors , one has @xmath64 , with correspondingly short wavelengths : in particular one can expect that already the friedel wavelength @xmath65 for a typical value of @xmath66 . in this case , the rapid oscillations of terms with @xmath67 give a vanishing contribution in eq . ( [ eq : coupl2 ] ) . we are assuming here that the molecule does not induce appreciable back - scattering on the cnt conduction electrons @xcite . these effects may be the subject of future investigations . only the _ long - wave _ term of the electron density survives , which reads @xmath68\label{eq : lw1}\ ] ] with @xmath69 the electron charge and @xmath70 ll field operators with @xmath71 and @xmath72 a short - length cutoff . as it is clear , the coupling involves the total charge sector @xmath73 only . + to proceed , we introduce @xmath74 with @xmath75 , and the canonically conjugated momenta @xmath76 . the charge sector @xmath73 of eq . ( [ eq : h0cnt ] ) becomes of @xmath77 and @xmath78 @xmath79 where @xmath80 . introducing @xmath81 and @xmath82 the hamiltonian of molecular vibrations becomes @xmath83 the coupling in eq . ( [ eq : coupl2 ] ) can be decomposed into three terms @xmath84 as @xmath85 where @xmath86 and @xmath87 here , we have introduced the dimensionless parameters @xmath88 with @xmath89 the characteristic oscillator length . + the terms in eq . ( [ eq : coup1 ] ) and eq . ( [ eq : coup2 ] ) can be promptly eliminated by means of a linear shift of the operators @xmath90 and @xmath91 . the shift of @xmath90 in eq . ( [ eq : coup1 ] ) leads to an offset of the gate potential considered in transport . the linear shift of @xmath91 produces a constant energy shift and hence its effects will be irrelevant on transport properties where only energy differences come into play . we can therefore discard terms in eq . ( [ eq : coup1 ] ) and eq . ( [ eq : coup2 ] ) and focus on eq . ( [ eq : coup3 ] ) , which couples the vibrational mode @xmath92 only to the plasmonic excitations @xmath77 . the bosonic part of eq . ( [ eq : h0cnt2 ] ) , eq . ( [ eq : h0mol2 ] ) and eq . ( [ eq : coup3 ] ) constitute a quadratic form which can be diagonalized by means of a canonical transformation @xcite @xmath93 the diagonalization procedure relies on the condition @xmath49 @xcite , i.e. @xmath94 . this is satisfied if @xmath95 with @xmath96 . for a typical value @xmath97 one obtains @xmath98 . + the diagonalized hamiltonian is @xmath99 written in terms of the new collective normal modes @xmath100 with energy @xmath101 , which exhibit a hybrid vibrational / plasmonic character . the coefficients @xmath102 are given by @xcite @xmath103^{-1/2}\ , , \ ] ] while the eigenenergies @xmath101 are obtained solving the self - consistent equation @xmath104 the condition @xmath105 ensures the positivity of the solutions of eq . ( [ eq : sceq ] ) preventing the wentzel - bardeen instability @xcite . as a general feature , the mode with @xmath106 is reminescent of a vibrational mode dressed by a polaron cloud with energy @xmath107 . as we will see , this polaron cloud has profound consequences on the transport properties of the system . all other modes with @xmath75 are plasmon - like with a slightly increased energy @xmath108 for @xmath109 . + for reasonable values of the system parameters ( see sec . [ sec : sec3 ] for further details ) @xmath110 , @xmath111 , @xmath112 and @xmath113 , one finds @xmath114 and @xmath115 . + due to the diagonalization , also the operator @xmath116 is modified . in the low energy sector , we are only interested into the vibration - like excitations , with an energy of the order of @xmath117 . we can thus disregard the electronic collective excitations and approximate @xmath118\ , .\label{eq : phicplus}\ ] ] , is capacitively coupled to the cnt . the tip is kept at a temperature @xmath119 while contacts are at a temperature @xmath120 . see text for further details.,width=377 ] let us now turn to a setup which allows to investigate the transport properties . it is schematically depicted in fig . [ fig : fig3 ] . the cnt - molecule system is tunnel - coupled to a lateral metallic contact and a stm tip , labeled respectively by the index @xmath121 , with tunneling amplitudes @xmath122 . the tip scans the entire cnt length . an additional gate , capacitively coupled to the cnt , is kept at a potential @xmath123 and allows to tune the cnt chemical potential . + a promising tool to extract information about the spectrum of molecular excitations even in the linear regime is the _ thermopower_. suppose that the lateral contacts are kept at a temperature @xmath120 while the tip is placed at @xmath119 , with @xmath124 . as a consequence of the temperature gradient , electrons flow through the cnt - molecule system the tip and the lateral leads are kept in an open - circuit configuration , which implies a steady current @xmath125 . as a result of the redistribution of eletrons , a voltage drop @xmath126 between the tip and the contacts develops . eventually , an _ equilibrium _ situation is reached . the _ thermopower _ @xmath127 is defined as @xmath128 in the linear regime , the equilibrium condition @xmath129 with @xmath130 the charge and thermal linear conductances of the system , allows to obtain @xmath131 we will consider the sequential tunneling regime , assuming that the typical tunneling rate throught the stm vacuum barrier or the leads barrier is large with respect to the average rate of electrons flow . this is valid when the temperature @xmath132 , the average level broadening due to tunneling , and the system is not in the deep coulomb blockade regime . however , it has been shown that for the low - temperature regime @xmath133 , both elastic and inelastic cotunneling contributions to the termopower have negligible effects even in the linear regime away from coulomb oscillation resonances @xcite . + a convenient tool to tackle the transport properties in the sequential regime is the master equation for the occupation probabilities of the cnt - molecule system states @xmath134 . as already stated , we are interested in energies _ smaller _ than @xmath135 , thus retaining only the vibration - like excitations . the cnt - molecule hamiltonian can thus be written as @xmath136 here we have included into the cnt - molecule hamiltonian the effects of the gate kept at a potential @xmath123 , where @xmath137 and @xmath138 the gate capacitance . + the contacts and stm tip are treated as noninteracting fermi gases . the tunneling hamiltonian which describes the connection between the cnt and the contacts is @xmath139 ( @xmath140 ) with @xcite @xmath141 where @xmath142 is the position of the lateral contact . here , @xmath143 is the field operator for _ right - movers _ in the cnt , with dirac valley index @xmath144 and spin @xmath145 . it is given by @xcite @xmath146 where @xmath147 is a klein factor and @xmath148 with @xmath149=i\delta_{j , j'}$ ] . the operator @xmath150 describes the forward propagating modes in the stm tip , with @xmath151 the vertical coordinate within the tip and @xmath152 the tip vertex . finally , @xmath153 are standard fermi operators describing electrons with spin @xmath145 and momentum @xmath154 in the lateral contact @xmath155 . + due to the spin - valley simmetry of a cnt , degeneracies occur in the spectrum of the hamiltonian eq . ( [ eq : hamham ] ) . in particular , we will consider in the following the resonance between states with @xmath156 ( filled shell , non degenerate ) and @xmath157 electrons , which is fourfold degenerate @xcite . we will label the cnt - molecule states as @xmath158 where @xmath159 is the vibrational quantum number , and keep track of the degeneracy via the factors @xmath160 . we note here that even though our calculations have been performed for a cnt with a full fourfold degeneracy , the model can promptly take in account chirality effects leading to the emergence of a lower , twofold degeneracy due to the generality of the factors @xmath161 . no qualitative modification of the results presented in the rest of the paper are expected in this case . the occupation probabilities @xmath162 of the system states are thus found , in the steady state , solving the master equation @xcite @xmath163 with the normalization condition @xmath164 . here , the tunneling rates are @xmath165 where @xmath7 is the stm tip position along the cnt . the steady current can be conveniently evaluated on either the tip or the lateral contact . one finds @xmath166 the tunneling rate for a transition between the initial state @xmath167 and the final state @xmath168 of the whole system - including the cnt , the stm tip and the lateral contact - is given by the fermi golden rule @xmath169 where @xmath170 , @xmath171 are the energies of the whole system in the initial and final state respectively . the calculation proceeds performing a trace of eq . ( [ eq : grule ] ) over the degrees of freedom of the tip and of the lateral contact , assumed in thermal equilibrium , in contrast with the charge degree of freedom and the occupation number of the vibrational state which retain their full dynamics . we will omit here the details of this standard procedure and directly quote the final results @xcite considering for simplicity the the case of tunneling into the cnt only @xmath172 where @xmath173 with @xmath174 the density of states of lead @xmath175 . here @xmath176 where @xmath116 is defined in eq . ( [ eq : phicplus ] ) , is a generalized fc factor , given by the overlapping of the wavefunctions of the molecular states @xmath177 ( with @xmath178 electrons ) and @xmath179 ( with @xmath180 electrons ) @xcite . finally , @xmath181^{-1}$ ] is the fermi function for lead @xmath182 at temperature @xmath183 ( @xmath184 , @xmath185 ) , @xmath186 and @xmath187 . note that in order to derive eqns . ( [ eq : r1],[eq : r2 ] ) we have assumed a symmetric voltage drop on both tunnel barriers . this choice is not restrictive for the present work as results in the linear transport regime do not depend on the particular choice adopted . + the _ position - dependent _ fc factors can be explicitly evaluated as @xmath188^{2|l'-l|}\frac{l_{<}!}{l_{>}!}\left[l_{l_{<}}^{|l'-l|}\left(\lambda^{2}(x)\right)\right]^{2}\label{eq : fc}\ ] ] with @xmath189 , @xmath190 , @xmath191 the laguerre polynomials and @xmath192^{2}+\frac{\omega_{0}}{\omega_{1}}\left[\sum_{\nu\geq1}\frac{k_{\nu 0}}{\nu}\cos\left(\frac{\pi\nu x}{l}\right)\right]^{2}}\label{eq : lambdaofx}\ ] ] a _ position - dependent cnt - molecule coupling parameter _ , whose explicit form depends on the diagonalization discussed in the previous section . + the coupling @xmath6 determines the behaviour of the tunneling rates and allows the possibility to trigger transitions between different molecular vibration state via the fc factors @xmath193 . when @xmath194 , one has @xmath195 and tunneling events are not able to trigger transitions among different vibrational states . on the other hand , @xmath196 for several different values of @xmath159 and @xmath197 when @xmath198 . the larger @xmath6 , the wider is the jump @xmath199 allowed by the fc factors , while transitions with @xmath200 and/or small @xmath201 are strongly suppressed . where @xmath6 is sizeable , the transport properties of the cnt are then drastically influenced . + in the linear regime , the strategy is to expand and solve eq . ( [ eq : master ] ) to linear order in @xmath126 and @xmath202 and then plug the solution into the current expression eq . ( [ eq : current ] ) , again retaining only the leading ( linear ) terms @xmath203 the procedure is lengthy but straightforward @xcite and shall be omitted here . we just quote the final results @xmath204\chi_{l , l'}(x)\ , , \label{eq : condv}\\ g_{t}=g_{0}^{(t)}f(-\bar{\epsilon})\sum_{l , l'}e^{-\beta l\omega_{0}}\left[\bar{\epsilon}+\omega_{ll'}\right]f\left[\bar{\epsilon}+\omega_{ll'}-k_{b}t\log(4)\right]\chi_{l , l'}(x)\ , .\label{eq : condt}\end{aligned}\ ] ] here , we have introduced @xmath205 , @xmath206 , @xmath207 , @xmath208^{-1}$ ] and @xmath209 with @xmath210 the barriers asymmetry ( @xmath211 for a typical stm setup ) . the logarithmic factors in eq . ( [ eq : condv ] ) and eq . ( [ eq : condt ] ) stem from the cnt spin and valley degeneracy and provide a shift of the peaks of @xmath212 and @xmath213 linear in temperature . we note here that the above results for @xmath212 and @xmath213 in the _ linear _ regime are identical to those which would have been obtained assuming the cnt and vibrational degrees of freedom fully relaxed @xcite . before discussing our results , let us review the parameters upon which our model holds . + the cnt - molecule coupling parameter @xmath6 in eq . ( [ eq : lambdaofx ] ) is influenced by the dimensionless parameter @xmath214 and to the dimensionless coupling strength @xmath215 defined in eq . ( [ eq : xidef ] ) . for librational modes one can estimate a typical frequency of the order of @xmath216 thz with @xmath217 , while _ for a weakly interacting cnt ( @xmath218 ) _ @xmath219 assuming @xmath220 , which yields @xmath221 . for shorter cnts , and/or for lower values of @xmath222 ( stronger interactions ) , @xmath182 decreases accordingly . in general , the larger the mismatch between the molecule and plasmon frequency - and thus the smaller @xmath182 - the weaker are the effects of the cnt - molecule coupling @xcite . the interaction strength @xmath215 in turn depends on the electron - molecule interaction strength @xmath223 , the cnt length and the molecule mass as well as on its vibrational frequency . typical values for @xmath223 are in the range @xmath224 @xcite . for the cnt , we assume here an average length @xmath225 and we consider fairly light molecules ( such as nh@xmath226 ) with average molar mass of about @xmath227 . this allows to estimate @xmath228 . + estimates for the interaction range @xmath56 in eq . ( [ eq : yukawa ] ) may be given on a phenomenological basis only . we expect it to be larger than the luttinger cutoff length , thus satisfying @xmath229 . in the following , we will consider values in the range @xmath230 . + the above estimates satisfy the condition in eq . ( [ eq : nowb ] ) , ensuring the stability of the system and the validity of the proposed model . + as a function of the position @xmath7 ( units @xmath231 ) of the stm tip along the cnt , for : + ( a ) different values of the molecule position @xmath232 : 0.125 ( red ) , 0.2 ( green ) , 0.3 ( blue ) , 0.5 ( purple ) . here , @xmath233 , @xmath234 and @xmath112 ; + ( b ) different values of @xmath215 : 0.01(red ) , 0.05 ( green ) , 0.1 ( blue ) , 0.15 ( purple ) , 0.2 ( cyan ) . here , @xmath235 , @xmath234 and @xmath112 ; + ( c ) different values of @xmath182 : 0.05 ( cyan ) , 0.2 ( purple ) , 0.4 ( blue ) , 0.6 ( green ) , 0.8 ( red ) . here , @xmath235 , @xmath110 and @xmath112 ; + ( d ) different values of @xmath236 : 0.1 ( red ) , 0.2 ( green ) , 0.3 ( blue ) , 0.4 ( purple ) , 0.5 ( cyan ) . here , @xmath235 , @xmath110 , and @xmath237 . + in all panels , @xmath238 and @xmath30 . the arrows denote the direction of increasing parameters.,width=377 ] figure [ fig : fig4](a ) shows the effective coupling parameters @xmath6 as a function of @xmath7 , for different positions of the molecule attached to the cnt . as a general feature , we observe that @xmath239 unless @xmath240 , i.e. when the molecule is very close to the drain contact ( a rather peculiar situation ) . this means that in general tunneling events at the lateral contact will be rather unefficient in triggering molecular vibrations . on the other hand , the stm tip - being able to scan the cnt length - can excite oscillations in the molecule when it is located in proximity of the latter . indeed , the curves in fig . [ fig : fig4](a ) always display a maximum of @xmath6 located at @xmath241 . this already suggests that the stm tip can be a valuable tool to investigate the properties of the molecule . this will be confirmed by the results on the thermopower shown later in this section . the value of @xmath242 exhibits a slight increase as @xmath243 ( or @xmath244 ) . this is due to the spatial behaviour of the long - wave electron density : indeed one finds that in the parameters regime considered in this work , when @xmath10 deviates from the cnt center , @xmath6 is dominated by terms with @xmath245 in eq . ( [ eq : lambdaofx ] ) . inspecting eq . ( [ eq : gamma3 ] ) one observes that these terms are all large and in phase when @xmath10 is near the cnt borders . + given the relatively large range of variation of the different system parameters , it is worthwile to investigate their effects on @xmath6 . figure [ fig : fig4](b ) shows @xmath6 for different value of @xmath215 . as it may be expected , since @xmath215 directly parameterizes the strength of the molecule - cnt coupling , @xmath6 increases ( decreases ) when @xmath215 increases ( decreases ) . a similar behaviour is observed when @xmath182 is varied - as shown in fig . [ fig : fig4](c ) . the coupling between the molecule and the cnt is more efficient if @xmath182 increases , i.e. when the vibrational frequency and the plasmon frequency are closer and thus more resonant . finally , fig . [ fig : fig4](d ) shows the dependence of @xmath6 on the width of the molecule - cnt interaction potential @xmath56 : the width of the effective coupling closely follows @xmath56 with its maximum scaling as @xmath246 , in agreement with the behaviour of @xmath52 in eq . ( [ eq : yukawa ] ) . + as a function of the position @xmath7 ( units @xmath231 ) of the stm tip along the cnt , for different values of the luttinger interaction parameter @xmath247 : 1 ( red , corresponding to @xmath248 ) , 0.8 ( green , @xmath249 ) , 0.6 ( blue , @xmath250 ) , 0.4 ( purple , @xmath251 ) , 0.2 ( cyan , @xmath252 ) . here , @xmath253 , @xmath254 , @xmath255 , @xmath233 , and @xmath112 , and @xmath238 . the arrows denote the direction of increasing @xmath222 and thus of _ decreasing _ interaction strength.,width=377 ] figure [ fig : fig5 ] shows the effects of coulomb interactions on the coupling @xmath6 . clearly , as @xmath256 ( from red to cyan curve ) the coupling gets suppressed . this fact is due to the decrease of the parameter @xmath257 . we want to stress here that additional effects induced by the presence of strong coulomb interactions , such as the formation of a wigner molecule in the cnt , are ignored since we assume the cnt to have a large number of particles @xmath258 with a corresponding wigner wavelength shorter than the width @xmath56 of the molecule interaction potential , see sec . 2 . the fact that the cnt - molecule coupling is larger for weakly interacting systems constitutes an advantage from the experimental point of view , due to almost unavoidable presence of surrounding screening metalizations . + ( units @xmath259 ) as a function of @xmath260 ( units @xmath117 ) ; ( b ) plot of @xmath213 ( units @xmath261 ) as a function of @xmath260 ( units @xmath117 ) . ( c ) plot of @xmath262 $ ] as a function of @xmath260 ( units @xmath117 ) . arrows denote the position of the exponentially suppressed vibrational sidebands induced by the coupling between the cnt and the molecule . ( d ) plot of the conductance maximum @xmath263 normalized to @xmath264 as a function of @xmath7 ( units @xmath231 ) for different temperatures @xmath120 ( units @xmath265 ) : 0.05 ( red ) , 0.1 ( green ) , 0.25 ( blue ) , 0.5 ( purple ) . parameters for all panels : @xmath110 , @xmath111 , @xmath112 , @xmath266 and @xmath238 . in panels ( a , b ) , @xmath267 and @xmath268.,width=377 ] let us now turn to the linear transport properties . before investigating the thermopower @xmath127 , it is useful to study the charge and thermal conductances . figure [ fig : fig6](a , b ) shows the typical behaviour of @xmath212 and @xmath213 as a function of the resonant energy @xmath260 , see eq . ( [ eq : resen ] ) . the linear charge conductance exhibits a peak centered around the main resonance value @xmath269 , while the thermal conductance shows a kink centered in the same position . these features are due to the contributions with @xmath270 in eq . ( [ eq : condv ] ) and eq . ( [ eq : condt ] ) . also the terms with @xmath271 and possibly @xmath272 , due to the excitation of the molecule vibrational modes , contribute to the above quantities and lead in principle to satellite peaks red- and blue - shifted with respect to the main resonance , located around @xmath273 ( @xmath274 an integer ) . this would in principle allow to directly extract the vibrational frequency of the molecule from a measurement of @xmath212 . these peaks , however , are not visible : in the regime @xmath275 they are exponentially suppressed , while at higher temperature they are subdued by the tails of the thermally - broadened central peak . figures [ fig : fig6](a , b ) indeed show no detectable trace of such sidebands . figure [ fig : fig6](c ) shows a plot of @xmath276}\ , .\ ] ] for a single conductance peak , one would expect a featureless exponential decay of @xmath212 . however , the plot shows faint oscillations at the vibron resonance positions @xmath277 . such oscillations are virtually undetectable in the linear plot of the conductance and extremely unlikely to be observed in experiment . also @xmath213 displays analogous features ( not shown here ) . + let us now analyze in more details the main peak of @xmath212 , concentrating on the low temperature regime @xmath278 . concentrating around @xmath279 and retaining only the terms @xmath280 in eq . ( [ eq : condv ] ) one obtains @xmath281}}\sum_{l}e^{-l\beta\omega_{0}}\frac{af_{ll}(x)}{a+4f_{ll}(x)}\ , , \label{eq : approxgv}\ ] ] where we have exploited the fact that @xmath239 . the conductance exhibits a maximum for @xmath269 with the well - known @xmath282 power - law scaling through the factor @xmath264 . when @xmath283 the conductance is essentially independent of the stm tip position , since conductance is dominated by the lateral conductance only . this case however is not very interesting from the point of view of a realistic stm setup , where @xmath211 . in this case , one can perform the summation in eq . ( [ eq : approxgv ] ) and obtain an analytic expression for the _ space - dependent _ conductance maximum @xmath284\ , .\label{eq : maxshape}\ ] ] the above expression is especially simple for @xmath275 when one finds @xmath285 . a plot of @xmath263 is shown in fig . [ fig : fig6](c ) as a function of @xmath7 for different temperatures . as expected by eq . ( [ eq : maxshape ] ) , it exhibits a dip in the location where the molecule sits . therefore , measuring the maximum of @xmath212 as a function of the stm position allows to extract @xmath6 and ultimately reveals the position of the molecule along the cnt . ( units @xmath286 ) as a function of @xmath260 ( units @xmath117 ) for : ( a ) the stm tip at @xmath287 ( away from the molecule , red ) and at @xmath241 ( ontop of the molecule , blue ) with @xmath288 and @xmath266 ; ( b ) for the tip at @xmath241 and different barrier asymmetries : @xmath266 ( red ) , @xmath289 ( green ) , @xmath290 ( blue ) , @xmath291 ( purple ) with @xmath288 ; ( c ) for the tip at @xmath241 and different temperatures @xmath120 ( units @xmath265 ) : 0.05 ( red ) , 0.1 ( green ) , 0.15 ( blue ) , 0.2 ( purple ) with @xmath266 . other parameters for all panels : @xmath110 , @xmath111 , @xmath112 , @xmath238 and @xmath292.,width=377 ] finally , we turn to the thermopower @xmath127 , shown as a function of @xmath260 in fig . [ fig : fig7](a ) . when the tip is away of the molecule , red line , it shows a featureless linear trend as a function of @xmath260 , typical of its behaviour around a coulomb blockade oscillation @xcite . we stress here that we are concentrating in a _ low - energy _ regime in which the electronic collective excitations of the cnt are effectively frozen out , leaving no signature on the thermopower @xmath127 . on the other hand , when the tip is located at @xmath241 , blue curve , a non - monotonic behaviour as a function of @xmath260 each sawtooth - like dip is located at @xmath277 ( @xmath274 an integer ) and signals the triggering of vibrational excitations in the molecule , in analogy to the behaviour observed in nano - electromechanical systems @xcite . the thermopower @xmath127 is therefore able to detect the presence of a molecule attached to the cnt , by displaying vibrational sidebands at @xmath277 . we remind here that usually , such vibrational sidebands are detected in the _ non - linear _ transport regime . since both @xmath213 and @xmath212 display the same exponential suppression for the vibrational sidebands , their ratio becomes insensitive to it . as a result , @xmath127 displays clear signatures of quantities not directly accessible in the direct measurements of the conductance @xcite . in analogy with @xmath212 , the visiblity of this effect is strongly influenced by the asymmetry of tunnel barriers @xmath293 , see fig . [ fig : fig7](b ) . as @xmath293 decreases , the sidebands get weaker and eventually vanish altogether when @xmath294 . the stm setup , therefore , operates in the correct regime to exploit the information contained into @xmath127 . also thermal effects tend to smear out the above features , as shown in fig . [ fig : fig7](c ) : in order to obtain the maximum contrast one needs @xmath275 . + ( units @xmath286 ) as a function of @xmath7 ( units @xmath231 ) and @xmath260 ( units @xmath117 ) . the dashed lines correspond to the values of @xmath260 chosen for the next panel . ( b ) plot of @xmath295 ( units @xmath286 ) as a function of @xmath7 ( units @xmath231 ) for different values of @xmath260 : @xmath296 ( red ) , @xmath297 ( green ) , @xmath298 ( blue ) . the dashed curve represents the analytic approximation in eq . ( [ eq : anaps ] ) . in all panels : @xmath110 , @xmath111 , @xmath112 , @xmath266 , @xmath238 , @xmath267 , and @xmath292.,width=377 ] the thermopower , however , encodes information about the _ position _ of the molecule as well . figure [ fig : fig8](a ) shows a colorscale map of @xmath127 as a function of the stm tip position @xmath7 and @xmath260 . following the graph along vertical lines , one obtains the @xmath127 vs. @xmath260 plots discussed above . for @xmath7 away from @xmath10 an increase of @xmath127 as a function of @xmath260 is observed , while features develop for @xmath299 . figure [ fig : fig6](b ) shows curves of @xmath127 as a function of the tip position @xmath7 for the resonance conditions @xmath277 ( @xmath300 ) . each of these curves exhibits a dip located at @xmath10 , thus confirming that the thermopower is a tool able to detect the location of the attached molecule . + in order to be more quantitative , we study the dip of @xmath127 around @xmath301 , considering for definiteness the low - temperature regime @xmath275 . only terms with @xmath302 and @xmath303 must then be retained in eq . ( [ eq : condv ] ) and eq . ( [ eq : condt ] ) . neglecting the logarithmic factors , irrelevant at small temperatures , one gets @xmath304 for @xmath211 . the plot of this expression is shown in fig . [ fig : fig8](b ) as a dashed dot , in agreement with full numerics . similar approximations can be obtained for the resonances at higher energy . their expressions hovever are too involved to be reported here . + thus , a measurement of @xmath127 as the tip scans the cnt allows to extract @xmath6 and confirms that thermopower is a powerful tool to extract information about the molecule and on its location . in this paper we have considered the transport properties of a cnt capacitively coupled to a molecule vibrating along its librational modes . the cnt - molecule coupling has been diagonalized exactly extracting the new eigenmodes of the system . transport in the presence of an stm tip scanning the cnt length has been considered . employing a master equation approach in the sequential tunneling regime , analytic expressions for the linear charge and thermal conductances have been obtained , allowing to study the behaviour of the thermopower . the transport properties depend on the tip position and are characterized by the appearance of a position - 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the transport properties of a cnt capacitively coupled to a molecule vibrating along one of its librational modes are studied and its transport properties analyzed in the presence of an stm tip . we evaluate the linear charge and thermal conductances of the system and its thermopower . they are dominated by _ position - dependent _ franck - condon factors , governed by a position - dependent effective coupling constant peaked at the molecule position . both conductance and thermopower allow to extract some information on the position of the molecule along the cnt . crucially , however , thermopower sheds also light on the vibrational levelspacing , allowing to obtain a more complete characterization of the molecule even in the linear regime .

SECTION 1. SHORT TITLE. This Act may be cited as the ``9/11 Immigrant Worker Freedom Act''. SEC. 2. ADJUSTMENT OF STATUS FOR CERTAIN WORKERS AFTER TERRORIST ATTACKS. (a) Adjustment of Status.--The status of any alien described in subsection (b) may be adjusted by the Secretary of Homeland Security to that of an alien lawfully admitted for permanent residence, if the alien-- (1) applies for such adjustment not later than 1 year after the date of the enactment of this Act, which may be extended at the discretion of the Secretary in cases with compelling circumstances; (2) is not inadmissible to the United States under paragraph (2) or (3) of section 212(a) of the Immigration and Nationality Act (8 U.S.C. 1182(a)), or deportable under paragraph (2) or (4) of section 237(a) of such Act (8 U.S.C. 1227(a)); except that in determining an alien's inadmissibility-- (A) offenses for which an essential element was the alien's immigration status shall not apply; (B) arrests or criminal charges on their own shall not apply; and (C) cases where a judgment has been expunged, set aside, or the equivalent shall not apply; and (3) not later than the date on which the application under paragraph (1) is submitted, satisfies any applicable Federal tax liability by establishing that-- (A) no such tax liability exists; or (B) all outstanding liabilities have been paid. (b) Aliens Eligible for Adjustment of Status.-- (1) In general.--The benefit provided by subsection (a) shall apply to any alien who-- (A) worked or volunteered onsite in rescue, recovery, debris cleanup, or related support services in lower Manhattan (south of Canal St.), the Staten Island Landfill, or the barge loading piers, for at least 4 hours during the period beginning on September 11, 2001, and ending on September 14, 2001, for at least 24 hours during the period beginning on September 11, 2001, and ending on September 30, 2001, or for at least 80 hours during the period beginning on September 11, 2001, and ending on July 31, 2002; (B) was a vehicle-maintenance worker who was exposed to debris from the former World Trade Center while retrieving, driving, cleaning, repairing, and maintaining vehicles contaminated by airborne toxins from the September 11, 2001, terrorist attacks for any time during the period beginning on September 11, 2001, and ending on July 31, 2002; (C) was a member of a fire or police department (whether fire or emergency personnel, active or retired), worked for a recovery or cleanup contractor, or was a volunteer; and performed rescue, recovery, demolition, debris cleanup, or other related services at the Pentagon site of the terrorist-related aircraft crash of September 11, 2001, during the period beginning on September 11, 2001, and ending on November 19, 2001; or (D) was a member of a fire or police department (whether fire or emergency personnel, active or retired), worked for a recovery or cleanup contractor, or was a volunteer; and performed rescue, recovery, demolition, debris cleanup, or other related services at the Shanksville, Pennsylvania, site of the terrorist-related aircraft crash of September 11, 2001, during the period beginning on September 11, 2001, and ending on October 3, 2001. (2) Exception.--An alien shall not be provided any benefit under this section if the Secretary of Homeland Security determines that the alien has willfully made a material misrepresentation or material omission in the proffer of information described in paragraph (1)(C). (c) Work Authorization.--The Secretary of Homeland Security may authorize an alien who has applied for adjustment of status under subsection (a) to engage in employment in the United States during the pendency of such application. (d) Construction.--Nothing in this section shall be construed to limit the existing authority of the Secretary of Homeland Security on the date of the enactment of this Act to require any form or other submission of information or to perform any background or security check for the purpose of determining the admissibility, or eligibility under this section, of any alien. (e) Waiver of Regulations.--The Secretary of Homeland Security shall issue guidance to carry out this section not later than 6 months after the date of the enactment of this Act, but is not required to promulgate regulations prior to implementing this section. (f) No Offset in Number of Visas Available.--When an alien is granted the status of having been lawfully admitted for permanent residence under this section, the Secretary of State shall not be required to reduce the number of immigrant visas authorized to be issued under the Immigration and Nationality Act (8 U.S.C. 1101 et seq.). (g) Definitions.--For purposes of this section: (1) The term ``applicable Federal tax liability'' means liability for Federal taxes, including penalties and interest, owed for any year for which the statutory period for assessment of any deficiency for such taxes has not expired. (2) Except as otherwise specifically provided in this section, the definitions used in the Immigration and Nationality Act (8 U.S.C. 1101 et seq.) (excluding the definitions applicable exclusively to title III of such Act) shall apply in the administration of this section.

9/11 Immigrant Worker Freedom Act This bill authorizes the Department of Homeland Security (DHS) to adjust to permanent resident the status a qualifying alien who applies for adjustment not later than one year after enactment of this bill and who, after the September 11, 2011, terrorist attacks: worked or volunteered on site in rescue, recovery, debris cleanup, or related support services in lower Manhattan, the Staten Island Landfill, or the barge loading piers for a specified number of hours during certain periods between September 11, 2001, and July 31, 2002; was a vehicle-maintenance worker who was exposed to debris from the former World Trade Center while retrieving, driving, cleaning, repairing, and maintaining vehicles contaminated by airborne toxins for any time during such period; or was a member of a fire or police department, worked for a recovery or cleanup contractor, or was a volunteer and performed rescue, recovery, demolition, debris cleanup, or other related services at the Pentagon site during the period between September 11, 2001, and November 19, 2001, or at the Shanksville, Pennsylvania, site during the period between September 11, 2001-October 3, 2001. DHS may authorize an alien who has applied for adjustment of status under this bill to work during the pendency of his or her application.

Please enable Javascript to watch this video SAND LAKE, Mich. — While police remain tight lipped on a now five-month-old homicide investigation involving a married couple in Newaygo County, case file documents detail a home in disarray the night of the killing and the discovery of suicide notes. Case files from the ongoing police investigation, obtained by FOX 17 through the Freedom of Information Act, describe the night of May 13 when Martin "Marty" Duram and his wife Glenna were found inside their home in the 9000 block of 128th Street, northwest of Sand Lake. Marty was shot and killed; Glenna was critically injured and barely alive when she was found. Autopsy results obtained by FOX 17 show Marty was shot five times, including once in the head, and was found with a clump of hair in his hand. First responders saw bullet casings on the bed near the victims and said Glenna was taken from the home strapped to a gurney because she was “very combative," according to case files. While trying to restrain her she said numerous times, “Why are you doing this Marty?" but gave no response when repeatedly asked who had shot her. Lilian and Chuck Duram, Marty's parents, believe it was a domestic dispute that went too far and reluctantly point the blame toward Marty's wife. “I feel when you kill somebody, you outta pay the bill," Chuck said. "When you take a gun and you shoot somebody five times, that’s upsetting." Marty and Glenna both had children from previous marriages. Police interviews conducted with children of both indicate the couple had a love-hate relationship. Glenna's son told police the couple argued “a lot," usually over money, and that Marty was possessive. Both had quick tempers. Glenna's daughter indicated to police that because Marty was so “controlling,” his wife had briefly left him for a period of time. While their children reported seeing them argue, none told police they ever witnessed the two physically fight. Marty's daughter claims every time she saw her stepmother, Glenna would say she was "just waiting for Marty to die to get all his money." In some instances, she'd make the comments in front of Marty and either appeared serious or would laugh about it. It's a description of their relationship echoed by Glenna's own daughter, who attested the two “loved to talk s**t." When asked by investigators if he believed Marty was killed during a botched murder-suicide, Glenna's son-in-law said, “I don’t buy it. They bicker, but I’ve never seen them get physical before.” Family said the couple had been married more than 10 years and had been living in their Sand Lake home for more than 15 years. The two always kept their doors locked, and none of the family had keys to the home, according to documents. For Marty's mother, Lilian, she said she never imagined outliving her own child. “I cry every night, and I wake up thinking, What’s the courts going to do, what’s the prosecutor going to do?" she said. "When is this going to be over with?" Several pages of the couple's gambling records obtained through the FOIA also show the two frequented casinos, but Marty's children claimed their father “would only go because Glenna wanted to,” the case files said. One document from 2010 showed Glenna gambled nearly $75,000 on slots, more than twice what Marty gambled that same year. Glenna was in charge of the couple's finances, and statements from several of the couple's children indicate their main source of income was money the state paid to Glenna for being Marty's primary caregiver and Social Security income Marty collected. Glenna became her husband's caregiver after he was seriously injured in an automobile accident in the 1990s. Roughly one month prior to his death, Marty learned his house was in foreclosure, according to relatives. Marty's children told investigators Glenna did not always pay the bills and would not tell Marty of their financial difficulties. For now, investigators refuse to answer any questions regarding the investigation. No arrests have been made and police have not publicly named any suspects. But, according to Marty's parents, evidence was found in the days after the killing of apparent suicide notes allegedly written by Glenna in the couple's home, both baffling and curious. The notes, found in a manila envelope in the couples living room, contained letters addressed to each of Glenna's children, “generally advising them (the addressed) that she was sorry and they were signed Love Mom, Love Glenna and Love Mom, respectively," documents said. When contacted by FOX 17 on Thursday, Glenna's daughter refused to comment. Relatives of Marty claim Glenna has been out of the hospital for several months, appearing at recent court hearings as the two sides of the family now battle over Marty's will. Documents show when police attempted to interview Glenna in the hospital in late May, she told investigators she didn't know how she wound up there. 43.323364 -85.576797 ||||| Watch Queue Queue Watch Queue Queue Remove all Disconnect ||||| NEWAYGO COUNTY, MI - Eight months have passed since a man was found shot to death alongside his critically injured wife in their Sand Lake area home, and his relatives say they've not been able to glean many details about how police have been investigating the homicide. Who killed Martin Duram? Who wounded his wife, Glenna Duram? Her injuries were so severe that when authorities first found her, they thought she was dead. While Martin Duram's family members have been vocal in their calls for justice, police and prosecutors remain tight-lipped about the open investigation into his slaying and the gunshot wound suffered by his wife. So far, no one has been charged with any crime related to his case. There are hundreds of pages of police reports detailing this investigation. Among them is an autopsy report indicating an underwear-clad Martin Duram, 46, was shot five times in the couple's Ensley Township home. Homicide scene had bullets on the bed, couple's house in disarray, documents show State police said early in the investigation that Martin Duram was the victim of a homicide. But investigators have refused to publicly state how his wife was wounded - whether they believe the gunfire stemmed from a domestic situation, or was the work of a third party. Glenna Duram's injury required months of rehabilitation care. In a recent interview, Newaygo County Prosecutor Robert Springstead said his office is nearing the final review of the case. Springstead said the events that unfolded at the couple's home in May "will all become clear pretty quickly" once his office receives final information needed from the investigation. Anyone who views it as an open-and-shut case simply doesn't know all the facts, he said. Meanwhile, Martin Duram's relatives have grown restless awaiting an arrest they anticipated months ago. "My biggest fear is nobody will be charged because it's taking so long. In my heart I feel like hopefully they're putting a good case together," Martin Duram's daughter, Jessica Duram, told MLive and The Grand Rapids Press. The 23-year-old said she formed an opinion about what occurred soon after her father's body was discovered, when she found a manila envelope in the living room containing three notes that "seemed to be suicide letters" signed by Glenna Duram, 47. Addressed to her adult children and ex-husband, the letters said she was sorry, according to police reports. Police did not find the letters when executing an initial search warrant; Martin Duram's children brought the notes to their attention while cleaning the home the following day. "I'm sure the family has already made up their mind about what happened," Springstead said. "I work on evidence and things I can prove, not gut feelings and hunches. Their gut feelings and hunches may end up being right, but I'm going to get all the information first." The investigation Police said the shootings occurred sometime between the evening of May 11 and afternoon hours of May 13, 2015. A concerned neighbor called authorities to the couple's home at 9242 E. 128th St. about 4:30 p.m. May 13 on what was first reported to be a suicide. The woman encountered the bloody scene and flagged down firefighters and first responders, who were down the road working on a fire. Details of the investigation that followed are contained in police and autopsy reports obtained by MLive and The Grand Rapids Press through Freedom of Information Act requests. The neighbor hadn't seen or heard from her friends in two days. She let herself into the Durams' unlocked home on her third attempt to reach them. She noted the home was locked when she'd tried earlier. Inside, she found the normally neat and organized single-story residence in "extreme disarray," she told police. A broken lamp and several items were strewn across the living room. Police determined there were no obvious signs of a break-in. Vigil planned for Sand Lake area homicide victim as family waits for answers from police Martin and Glenna Duram were found lying on the bedroom floor near the bed, where there was blood "all over," according to the police report. Glenna Duram's body was covered by a blanket, with only her head exposed. Three empty firearm cartridges and one full cartridge were on the end of the bed. Martin Duram had been shot five times, records show. Three gunshots were fired at his chest from close range, according to the autopsy report. The remaining bullets were fired into his back and forearm from an undetermined or distant range. Glenna Duram was also shot, and paramedics observed a wound behind her right ear. Her shoulders, hair and clothes were covered in blood. Further details of her injuries were redacted from the police reports released to MLive. Authorities noticed blood stains on a couch and bullets in the living room. A Ruger pistol was found under a living room chair and taken from the home during the search warrant process. The kitchen showed signs of an interrupted meal and a dog that had been left alone for hours or maybe even days. Police observed a bowl of spaghetti and garlic toast on the kitchen table. Near the back door, they saw feces in a pair of shoes. It took more than an hour for authorities to realize Glenna Duram was still alive, records showed. Sand Lake firefighters and first responders initially checked the home for what they believed was a suicide call, then backed out to await authorities upon seeing bullets in the bedroom. The first responders believed both victims were dead and did not check their pulses, according to police reports. Police went back in to clear the home and retrieve the couple's growling dog, and it was then they observed Glenna Duram was still breathing. In the ambulance en route to Spectrum Health Butterworth Hospital, Glenna Duram was confused and combative, reports show. She asked numerous times, "Why are you doing this, Marty?" as she was being restrained. She complained that someone was stepping on her hair as she was carried out of the home. Martin Duram's autopsy showed hairs were found in his right hand. Home life Following the homicide, dozens of interviews conducted by state police included questions about the couple's relationship and home life. Those closest to the couple claimed it wouldn't have made sense for the attack to be the work of a random intruder; Martin Duram was extremely cautious of strangers and kept his home's doors locked and dead-bolted. Martin and Glenna Duram, both of whom have children from previous marriages, were private people. The couple didn't have many close friends, his sons told police. If he opened the door for a stranger, it would've been with a gun in his hand. Family said he and Glenna loved each other, though they had faced some rough patches. They argued, but no one could recall physical fights. They loved to "talk sh--" and joke with each other, Glenna Duram's daughter told police. Martin Duram's mother, Lillian, said the couple engaged in "fun-type bickering." Among the jokes were frequent comments made by Glenna Duram that she was waiting for her husband to die, or was going to kill him so she could collect his money and possessions, according to police reports. She said the statements in front of her husband, sometimes appearing serious and sometimes laughing, family later told police. "He would laugh about it like 'Yeah, you're not getting anything from me.' Other than that it didn't seem to bother him," said Jessica Duram, who thought the situation was strange but viewed it as a running joke. Martin Duram suffered a traumatic brain injury in a car crash in the 1990s, and his wife became his caregiver after they married in 2000. Relatives told investigators the couple's main sources of income were payments Glenna Duram received from the state and her husband's Supplemental Security Income. "She indicated he was a pain in the ass to take care of and one of these days she was gonna kill him," a detective wrote in the report when describing an interview with a relative of one of Martin Duram's sons. Sand Lake homicide victim remembered for love of family, the outdoors Jessica Duram said her father wore a leg brace and could walk, but relied on his wife to drive him to doctor's appointments. His disability seemed to hinder him more as he aged. Still, he loved spending time outdoors and was an avid hunter. He kept numerous guns - an estimated 20 long guns and several handguns, some of which he had been holding for his father - in a large safe in the home. Financial problems Relatives said the couple lived frugally by keeping the heat down and the lights off so they could spend money on their hobbies. Police were told they frequented area casinos. Family and neighbors said the Durams' home was in foreclosure, citing papers left on the couple's door a few days prior to the shootings and a listing in the local newspaper. Lillian Duram said her son was unaware his home was in foreclosure until she notified him about the newspaper listing not long before his death. She claimed Glenna Duram insisted the listing was an error. Jessica Duram said she and her brothers found ripped-up foreclosure papers in her stepmother's belongings. She and others speculated the issue may have led to a fight that escalated. Glenna Duram yelled out her husband's name when police first tried to interview her at the hospital. Later, she only gave brief responses from her hospital bed and said she didn't know what had happened. She told police no one had keys to their home. The police report provided to MLive does not include other interviews with Glenna Duram, and Springstead declined to say if she has been interviewed since. In June, her mother told police that Glenna Duram's last memory was three days before she was found. Glenna Duram had sent her mother a text message saying "love you sorry" right before the incident, but her mother said she was apologizing for falling through on earlier plans and losing money at the casino. Attempts to reach Glenna Duram were not successful, and messages left for her relatives were not returned. "We do a lot of assuming. We do a lot of guessing and we really would like the story put together, but we're never going to have it," Lillian Duram said. "We just really want this closed." Angie Jackson covers public safety and breaking news for MLive/The Grand Rapids Press. Email her at [email protected], and follow her on Twitter. ||||| SAND LAKE, Mich. (WOOD) — Bud is an African grey parrot with a filthy mouth who also may have witnessed his owner’s murder, relatives of the victim say. “Don’t f—ing shoot,” the bird says on a video that the family says it took several weeks after the shooting. Martin Duram, 45, was shot and killed in his home on 128th Street in Ensley Township in May 2015 in what police first thought was a double-homicide. Police also found his wife, Glenna, in the home with a gunshot wound to the head. They realized an hour later she was still alive. Now, Michigan State Police reports obtained by 24 Hour News 8 under the Freedom of Information Act list the wife as a suspect, suggesting she tried to pull off a murder-suicide. She has since recovered from her injury. Duram’s parents said they’re frustrated that nobody has been charged in the death. They also say they believe the bird is a witness. “That bird picks up everything and anything, and it’s got the filthiest mouth around,” Duram’s mom, Lillian Duram, said. The bird, they said, mimicked both Durham and his wife. The video shows the bird, clinging to the outside of a cage, changing voices, almost as if it were arguing. “I personally think he was there and he remembers it and he was saying it,” Duram’s father, Charles Duram, said. Police reports obtained by 24 Hour News 8 show that a witness asked police whether they could use the bird as evidence, but they don’t show that the detective responded. Newaygo County Prosecutor Robert Springstead said he’s aware the couple had a bird that talked but that he had not seen the video. The owner of Casa La Parrot in Grand Rapids said it’s not unusual for African grey parrots to mimic male and female voices. “It’s definitely an argument between a man and a woman,” she said after watching the video. She said she clearly heard the bird say, “Don’t f—ing shoot.” African grey parrots usually mimic things they’ve heard repeatedly, but she said birds can say words they’ve heard just a few times. “In my mind, it’s something that he’s heard, definitely heard before. And if it’s fresh in his mind, he might even say it more now,” she said. State police identified the wife as a suspect in a murder-attempted suicide, suggesting she shot him five times before turning the gun on herself. Police records detail financial problems, gambling problems and a potentially troubled marriage, ending with the killing of Martin Duram with a gun he kept at his home. Police say Glenna Duram left three suicide notes, one to her ex-husband and one to each of her children: “i’m sorry but i love you and soo sorry i’ve been a disappointment to you these last 12 yrs or so Please forgive me your one of the best things I ever did — Love mom.” But in an interview with police after she recovered, she denied killing him, saying she remembered nothing until she was in the hospital. “I know for a fact I didn’t kill my husband,” police quoted her as saying. She also said she didn’t remember writing the suicide letters, but a handwriting analysis showed she did, police said. The victim’s mom wonders why prosecutors haven’t filed charges. “It’s frustrating. I cry,” she said. “The worst thing for a husband to do is look over at his wife crying and there’s absolutely no way of comforting this woman because there’s no settlement there at all,” her husband said. The victim’s father said he is not ready to convict his daughter-in-law. “I got hope that maybe there’s something out there that we don’t know about that can change this whole situation,” he said. His wife disagrees. “The b—- did it,” she said. The prosecutor said he expects to decide in two or three weeks whether to file charges. He said he’s waiting for Michigan State Police to finish the investigation. “There’s some evidence to support” the theory that Glenna Duram killed her husband, Springstead said. “Although the law allows charging on probable cause, I don’t like to do that, especially when you have a very serious case,” he said. “When the investigation is done, I like to be satisfied there’s proof beyond a reasonable doubt.” Share this: Email Print Facebook Twitter Google Pinterest More LinkedIn Tumblr Reddit

– Can a foul-mouthed parrot act as a witness to a murder? That's the question Martin Duram's family wants answered after Duram was killed in his Michigan home in May 2015, WOOD reports. Weeks after the murder, Duram's African grey parrot, Bud, could be heard repeating the phrase "Don't f---ing shoot." Bud would also talk to himself in two distinct voices in what the owner of a Michigan exotic bird store says is “definitely an argument between a man and a woman.” According to MLive, Duram, 45, was shot five times while clad only in his underwear. His wife, Glenna, was found with a gunshot to the head but survived. She's now a suspect in a possible failed murder-suicide. Glenna's daughter from another marriage told Fox 17 her mother and Duram were frequently talking trash to each other. Family members recall Glenna frequently talking about killing Duram or simply waiting for him to die, only sometimes seeming to be joking. The couple had money and gambling issues, and Duram required special care after suffering a brain injury in a car crash. But with more than a year having passed with no charges filed, Duram's family is getting fed up. They have video of Bud reenacting what they say are the final moments of Duram's life, and they want police to listen to what the parrot has to say. “That bird picks up everything and anything, and it’s got the filthiest mouth around,” Duram’s mother tells WOOD. (This parrot was actually detained by police.)

the behavior of many - body systems involving quantum spins has been one of the central topics in recent years since the properties of such systems are relevant to a great variety of materials , mostly oxides . the structure of the ground state and the various symmetry broken phases that emerge are issues of special interest , especially in systems of low - dimensionality and/or where frustration is present . @xcite in this context the heisenberg model on the three - dimensional pyrochlore lattice consisting of corner sharing tetrahedra , shown in fig . [ fig1](a ) , is in a league of its own . the pyrochlore lattice is strongly geometrically frustrated and is relevant to numerous compounds . it has been argued that no magnetic order is present in the ground state . @xcite the effects of various additional interactions have also been studied , such as magnetoelastic couplings , @xcite long - range dipolar interactions , @xcite and orbital degeneracy . @xcite these interactions ( in addition to various anisotropies ) can generally lead to bond , magnetic and/or orbital order , and which of them is dominant depends on the details of the model relevant to the specific class of materials . in the present work we study a new mechanism for magnetic order in the s=1/2 pyrochlore lattice , driven by the dzyaloshinsky - moriya ( dm ) interactions . in the pyrochlore such interactions are expected to be present by symmetry . for the s=1/2 heisenberg model on the pyrochlore lattice it has been suggested @xcite that the ground state is dimerized ( non - magnetic ) , but macroscopic degeneracy still remains . for certain other lattices , such as the 2d pyrochlore and related models , @xcite the ground state is a unique valence bond solid , and while the dm interactions ( if present ) can lead to non - trivial order in the ground state , such dm induced order can only occur above a critical threshold , due to its inherent competition with the underlying dimer order . @xcite in this work we show that in the 3d pyrochlore antiferromagnet , where a macroscopic degeneracy is present , the dm interactions have a more profound effect and can lift the degeneracy , leading to a chiral antiferromagnetic state with a small staggered magnetic moment . in an external magnetic field quantum transitions between weakly ordered states with different symmetries , depending on the field direction , are possible . we determine the field - induced patterns for several field orientations , generally pointing in highly - symmetric crystal directions . the phase diagram at finite temperature is also briefly discussed . the spin hamiltonian ( s=1/2 ) is @xmath0 where @xmath1 are the dm vectors , to be specified later . we start by summarizing the results for @xmath2 , i.e. the heisenberg case . our starting point is the strong - coupling approach , similar to that of refs . , with the lattice divided into two interpenetrating sub - lattices , one of them formed by strong " tetrahedra ( with exchange @xmath3 ) , connected by weak " tetrahedra ( exchange @xmath4 ) . the strong " tetrahedra then form a fcc lattice , as shown in fig . [ fig2](a ) , where every site represents a tetrahedron , and one can attempt to analyze the structure of the ground state starting from the limit @xmath5 . for @xmath6 the tetrahedra are disconnected , and on a single tetrahedron the ground state is a singlet and is twofold degenerate . we choose the two ground states as : @xmath7[3,4]+[2,3][4,1]\}$ ] , @xmath8[3,4]-[2,3][4,1]\}$ ] , where @xmath9 $ ] denotes a singlet formed by the nearest - neighbor spins @xmath10 and @xmath11 , labeled as in fig . [ fig1](b ) . in the pseudo - spin @xmath12 representation , so that @xmath13 corresponds to @xmath14 and @xmath15 corresponds to @xmath16 , one finds that third order is the lowest one contributing to the effective inter - tetrahedron hamiltonian in the singlet sub - space : @xcite @xmath17 + \mbox{const.},\ ] ] where @xmath18 @xmath19 in the two - body part we have defined @xmath20 all remaining @xmath21 . the site indexes @xmath22 refer to the fcc lattice made of individual tetrahedra , fig . [ fig2](a ) , and it is sufficient to know the interactions on one `` supertetrahedron '' , shown in green ( containing the sites 0,1,2,3 ) . in the three - body interaction the indexes run over the values : @xmath23 . on a mean - field level the ground state of @xmath24 is defined by the following averages : @xmath25 this means that while a dimerization pattern sets in on sites 1,2,3 , the pseudospins on the `` @xmath26 '' sites , shown in blue in fig . [ fig2](a ) remain `` free '' , i.e. there is no fixed dimer pattern on those sites and consequently a macroscopic degeneracy remains . @xcite one should certainly keep in mind that the strong - coupling approach breaks artificially the lattice symmetry and while one hopes that the structure of the ground state is correct even in the isotropic limit @xmath27 , it is very difficult to assess this by other means ( e.g. exact diagonalizations ) at the present time . nevertheless this approach is expected to provide reliable description of the ground state properties as long as the relevant physics remains in the singlet subspace , i.e. the triplet modes stay high in energy and no magnetic order is generated , as might be the case for the pyrochlore antiferromagnet due to the strong frustration . fluctuations around the mean - field solution , eq . ( 6 ) , can lift the degeneracy , leading to unique dimer order . however the corresponding degeneracy lifting energy scale is very small , @xcite of the order of @xmath28 . a unique ( singlet ) ground state is also produced if one starts the expansion from a larger cluster of 16 sites , with an ordering energy scale ( energy gain ) of @xmath29 , extrapolated to the limit where all couplings are equal . @xcite in what follows we will take the mean - field solution as a starting point and discuss a physical mechanism , based on the presence of interactions beyond heisenberg exchange , that can lead to the lifting of degeneracy and consequently to ( magnetic ) order in the ground state . between them . ( b ) antiferromagnetic chiral order on the blue ( dark gray ) tetrahedra , with magnetic moment @xmath30 , induced by the dm interactions . on the gray tetrahedra ( labeled as 1,2,3 ) the order has the same symmetry , but is much weaker @xmath31 , eq . ( 9 ) , and is not shown . ] now we consider the effect of the dm interactions @xcite on the ground state properties . on a single tetrahedron the dm vectors are distributed as shown in fig . [ fig1](b ) , or explicitly : @xmath32 , @xmath33 , @xmath34 , @xmath35 , @xmath36 , @xmath37 . here @xmath38 is the magnitude of the ( all equal ) dm vectors . the directions of the dm vectors respect the pyrochlore lattice symmetry and thus the dm interactions are expected to be always present in the system . @xcite since @xmath39 originate from the spin - orbit coupling , @xcite we have @xmath40 , and typically the values of the dm interactions are several percent of the heisenberg couplings . there are two dm distribution patterns that are equally acceptable on symmetry grounds - the one shown in fig . [ fig1](b ) , and one with all directions of the vectors @xmath39 reversed ( @xmath41 ) . these two cases were named , respectively , `` indirect '' and `` direct '' in ref . . the reader is referred to that paper for more details on moriya s rules as applied to the pyrochlore lattice . in the extreme quantum case of s=1/2 , and within our approach , we have found that the two allowed ( by symmetry ) dm distributions lead to qualitatively the same physics ( see discussion following eq . ( 8) ) . following the strong - coupling approach outlined above for the purely heisenberg case , we have to determine how the singlet ground states @xmath42 on a single tetrahedron are modified by the presence of @xmath38 . since the dm interactions break the spin rotational invariance , they admix triplets to the two ground states , not lifting their degeneracy . @xcite we will also be interested in effects in the presence of an external magnetic field , and in this case the field ( in combination with the dm interactions ) also mixes certain triplet states with @xmath42 . in order to determine the additional contributions to @xmath24 , it is convenient to express the spin operators on a singlet tetrahedron , labeled as in fig . [ fig1](b ) , in terms of the pseudospin operators . for magnetic field @xmath43 ( along the @xmath44 bond ) , assuming @xmath45 and @xmath46 , we obtain ( defining the rescaled quantities @xmath47 along the way ) : @xmath48 the notation @xmath49 simply combines in one line the formulas for both @xmath50 and @xmath51 , where @xmath52 and @xmath53 label sites on a tetrahedron ( as defined in fig . [ fig1](b ) ) , while the left index in @xmath49 corresponds to the upper sign on the right hand side , and the right index - to the lower sign . the formulas eq . ( 7 ) are obtained by using the ground state wave - functions , written explicitly in ref . ( 2,5 ) ) , to lowest order in @xmath54 and @xmath55 . for magnetic field in the @xmath56 direction , the corresponding expressions are given in appendix a. first we analyze the case of zero magnetic field ( @xmath57 ) . taking into account the connections between the tetrahedra ( green bonds in fig . [ fig2](a ) ) , and using eq . ( [ operatorsdm ] ) , we obtain an additional interaction term , so that the full effective hamiltonian @xmath58 becomes @xmath59 where @xmath24 is the part originating from the heisenberg exchanges , eq . the above result is obtained in lowest , first order in @xmath4 . while extra terms of the same power @xmath60 also arise from the dm interactions @xmath61 on the inter - tetrahedral bonds , we find that they only give a small renormalization of the energy scale @xmath62 in eq . ( 2 ) and are , therefore , neglected . we would like to also point out that in general the coupling constant in @xmath58 is not symmetric under @xmath63 . to verify this requires a calculation of the next to leading order in @xmath54 in eq . we have found that , in the case of zero field @xmath64 , the next order present is @xmath65 , and one has to substitute in all formulas @xmath66 . consequently the same substitution has to be made in the coefficient @xmath67 in eq . ( [ phamdm ] ) . most importantly however the @xmath68 structure of the interaction is not affected by increasing the strength of @xmath69 , and from now on we will work with the leading order in @xmath54 . therefore the physics ( ground state structure ) associated with the two dm distribution patterns will be the same . this conclusion might be connected with the fact that we have kept only the lowest non - trivial order in the coupling @xmath4 in the effective hamiltonian - we have used this as our guiding principle as the difficulties associated with the derivation and analysis of higher orders seem insurmountable . we have performed mean - field calculations of the hamiltonian defined by eqs . ( 2,[pham2],[pham3],[phamdm ] ) in the unit cell of fig . [ fig2](a ) , as represented by the four sites connected by green lines . the results can be particularly simply summarized in the limit @xmath69 , which is also the case of physical relevance . it is physically clear that ferromagnetic order in the @xmath70 component is generated on the @xmath71 sites , since no order in the @xmath72 components ( dimer order ) was present on those sites without dm interactions ( on mean - field level ) , eq . indeed we find @xmath73 , while for the other sites we have , to lowest non - trivial order in @xmath38 , @xmath74 . from eq . ( [ operatorsdm ] ) it is then clear that a non - zero average of the operator @xmath70 corresponds to a finite moment in the ground state , with magnitude @xmath75 . to summarize : @xmath76 here @xmath77 stands for the magnitude of the moment on each site of pyrochlore lattice , belonging to a tetrahedron labeled by the index @xmath78 . from ( [ operatorsdm ] ) it follows that the moments point out of the cube s center ( the cube is defined in fig . [ fig1](b ) ) , leading to formation of sublattices and the order shown in fig . [ fig2](b ) . since from eq . ( [ moment ] ) @xmath79 , we have neglected the magnetic order on those tetrahedra . the antiferromagnetic order of fig . [ fig2](b ) corresponds to non - zero scalar chirality @xmath80 , where @xmath81 are any three spins on a given tetrahedron . the ising symmetry @xmath82 is spontaneously broken in the ground state , which in terms of real spins corresponds to the time - reversal symmetry broken state of fig . [ fig2](b ) . in this state the two ground state wave functions @xmath83 and @xmath84 ( see ( a1 ) ) form linear combinations in the `` chiral '' sector : @xmath85 , where @xmath86 are real coefficients ( @xmath87 ) . this combination is ferromagnetically repeated on every @xmath88 ordered tetrahedron . a straightforward calculation shows that both @xmath89 . the energy gain ( per site of fig . [ fig2](a ) ) from the formation of the ordered state is @xmath90 . the order we have just discussed is in competition with other mechanisms for lifting of the degeneracy that could originate from the heisenberg interactions themselves ( e.g. fluctuations beyond the mean - field ) , typically also leading to very small energy scales . in the presence of an external magnetic field other possibilities for lifting of the degeneracy exist . we will consider three symmetric field orientations , for which the results are particularly transparent . the magnetic field generally leads to splitting of the ground states , which in the language of the pseudospins produces an on - site effective magnetic field " @xmath91 in the pseudospin @xmath56 direction . the effective hamiltonian has the form @xmath92 we consider fields in the @xmath93 and @xmath94 directions , as well as comment on the case @xmath95 , where the axes are defined in fig . [ fig1](b ) . using the wave - functions in a field we obtain ( see eq . ( a3 ) ) : @xmath96 @xmath97 in ( [ phamfield ] ) represents lattice contributions , originating from the various combinations in eq . ( [ operatorsdm ] ) once the tetrahedra are coupled , and also producing terms of order @xmath98 . these terms are cumbersome and are not explicitly written , but their effect is taken into account in the ( numerical ) mean - field implementation within the unit cell of fig . [ fig2](a ) . a further discussion appears in appendix b. direction . upper row : field - induced order on the rest of the tetrahedra . the tetrahedra are labeled 0,1,2,3 as in fig . 2(a , b ) . blue ( dark gray ) arrows in ( a , b ) correspond to moments @xmath30 , while the red ( light gray ) arrows on the upper row and ( b , c ) are the field - induced moments @xmath99 . ] we will mostly discuss the two cases with @xmath100 . then the on - site @xmath91 term in eq . ( [ phamfield ] ) is responsible for the main effect , namely competition between order in the @xmath101 pseudospin component and order in the chiral " @xmath70 component favored by eq . ( [ phamdm ] ) . therefore the physics is that of the transverse field ising model ( although in our case the unit cell is larger ) . it is also clear that the mentioned competition is most effective on the @xmath71 ( blue ) sites , while the non - zero averages of @xmath102 on the other sites are not much affected by the presence of small @xmath38 and @xmath103 . we have found that a quantum transition takes place between a state with @xmath104 and @xmath105 . the result for @xmath106 can be written in an explicit way , and we have for the field @xmath43 @xmath107 , \ \ \tilde{h } \leq \tilde{h}_{c } \approx 5.3 \sqrt{\frac{j}{j ' } } \tilde{d } \label{critical}\ ] ] @xmath108 ( and @xmath109 since @xmath110 ) . the values of the spin moments for given values of @xmath111 on a tetrahedron can be determined directly from eq . ( [ operatorsdm ] ) . on the @xmath71 ( blue ) sites this leads to evolution of the magnetic order as shown in fig . [ fig3](a , b , c ) . for @xmath64 there is only chiral order ( blue arrows ) with moment @xmath30 , changing , for @xmath112 into a combination of chiral and field induced order ( red arrows ) with @xmath99 . gradually , as @xmath103 approaches @xmath113 the chiral order diminishes ( eq . ( [ critical ] ) ) , leaving for @xmath114 only the field - induced component , equal to @xmath115 . on the tetrahedra @xmath116 labeled as in fig . [ fig2](a , b ) there is virtually no evolution as a function of the field , and the order is determined by eq . ( [ operatorsdm ] ) with @xmath117 fixed by the heisenberg exchanges , see eq . this leads to the magnetic moments ( proportional to @xmath55 ) shown in fig . [ fig3 ] , upper row . on tetrahedra @xmath118 and @xmath119 the spins point along the internal diagonals of the cube perpendicular to the field . dimerization is also present in the ground state ( bolder lines = stronger bonds ) and co - exists with the magnetic order . blue ( dark gray ) arrows in ( a ) correspond to the dm induced order with @xmath30 , red ( light gray ) arrows on the upper row and ( c ) correspond to the field - induced component @xmath99 , and black arrows in ( b ) are a mixture of the two . ] a similar quantum transition takes place for magnetic field in the @xmath56 direction @xmath120 . in this case the formulas ( a2 ) from appendix a have to be used , and the field - induced order is shown in fig . the critical field is also somewhat smaller in this case @xmath121 , mainly due to the fact that @xmath91 is larger by a factor of 2 , see eq . ( 11 ) . for other , less symmetric field directions , the form of the effective hamiltonian , and consequently the field - induced patterns can be quite complex . finally , in the case of a field @xmath122 , when @xmath123 , the quantum transition described above does not take place , and the chiral order of fig . [ fig3](a ) essentially does not evolve . in this case the various additional terms similar to the ones described in appendix b may lead to small , sub - leading deviations from the perfect chiral sate . in addition to the field - induced ordered patterns of fig . [ fig3 ] and fig . [ fig4 ] , determined mostly by the inter - tetrahedral interactions , a single tetrahedron with dm interactions also possesses a finite moment in the direction of the field , @xcite meaning that the spins in fig . [ fig3 ] and fig . [ fig4 ] would also tend to tilt in that direction . however the moment along the field is proportional to @xmath124 , as can be deduced from the fact that the ground state energy varies as @xmath125 from ( a3 ) . consequently this component has not been taken into account in eqs . ( [ operatorsdm],a2 ) , valid to lowest order in @xmath126 . finally , we emphasize that while we have assumed @xmath126 to be small , the ratio @xmath127 can be arbitrary , meaning that the quantum transitions in a field are within the limit of validity of our approach . at finite temperature we expect the phase diagram to look as presented in fig . [ fig5 ] ( it is assumed that @xmath128 ) . the higher transition temperature @xmath129 corresponds to the scale below which the translational symmetry is broken ( dimerization occurs ) , and is determined by the energy scale in @xmath24 for @xmath130 , eq . ( 2 ) . we expect @xmath131 to have weak dependence on magnetic field when dm interactions are present . at a lower scale @xmath132 the ising @xmath133 symmetry is spontaneously broken by eq . ( [ phamdm ] ) . for @xmath64 we can estimate @xmath134 . at fixed field this finite - temperature transition is in the 3d ising universality class , and the specific heat diverges as @xmath135 . @xcite we emphasize that fig . [ fig5 ] shows only the low - field part of the phase diagram ( since @xmath136 ) , while the physics at high fields can not be determined within the effective hamiltonian framework presented here . ) and dm interactions . ] in certain pyrochlores , such as the gadolinium titanium oxides with s=7/2 , field - driven phase transitions have been observed , @xcite although in this material the magnetic order is typically explained as originating from the long - range dipolar interactions . for such large value of the spin the dm mechanism for magnetic order , at least the way it is developed in this work , should not be effective since our calculations were based on strong singlet correlations in the ground state . at the moment it is hard to point out a class of materials where the dm interactions are definitely expected to be dominant with respect to other anisotropies capable to produce ordering ; some possible examples are given in ref . . in particular , our results are specific to the case @xmath137 , while most currently known pyrochlores have higher @xmath138 . let us also point out the main differences between the present work and the purely classical model : @xcite ( a. ) we have found that the antiferromagnetic order is _ weak _ , determined by the dm interaction scale itself , ( b. ) the `` chiral '' non - coplanar pattern is the stable one for @xmath137 in the absence of a field . field - induced patterns then dominate for @xmath139 . let us also give some estimates : if we take the optimistic viewpoint and apply our formulas to the case @xmath140 , and take @xmath141 , then the characteristic temperature for onset of chiral order would be @xmath142 , and the magnitude of the moment @xmath143 . the characteristic critical fields would be @xmath144 . these should be viewed as order of magnitude estimates . inevitably the scale @xmath132 falls into the @xmath145 range , which , in combination with the smallness of @xmath146 itself , would probably make the chiral state rather hard to observe with neutron scattering techniques used to probe the spin structure . @xcite the spectral weight of magnetic excitations in such neutron scattering measurements would be determined by @xmath38 itself . however the scale of @xmath147 of around @xmath148 or smaller ( also determined by @xmath38 ) , means that the various field - induced patterns , strongly dependent on the magnetic field direction , might be accessible . in conclusion , we have shown that dm interactions can induce weak antiferromagnetic order characterized by non - zero chirality . in an external magnetic field quantum transitions between the chiral state and field - induced ordered states take place . field - induced patterns with different symmetries depending on the direction of the field are very characteristic of the presence of dm interactions . we have used an expansion around a configuration which breaks the lattice symmetry @xcite and leaves a macroscopic degeneracy , subsequently lifted by the dm interactions . full restoration of lattice symmetry within such an approach seems impossible to achieve , as it is impossible for example in the large - n approach . @xcite nevertheless we expect that without dm interactions the ground state properties and the inherent degeneracy present in this strongly frustrated magnet are well accounted for . in this situation the dm interactions push " the pyrochlore lattice towards the ordered states analyzed in the present work . more generally , the dm interactions can be relevant and lead to weak antiferromagnetism in strongly frustrated systems , where the heisenberg exchanges on their own fail to produce long - range order . we also emphasize that the physics behind the weakly antiferromagnetic states with different symmetries discussed in this work is very different from the phenomenon of weak ferromagnetism , usually associated with dm interactions . stimulating discussions with h. tsunetsugu , o. tchernyshyov and c. lhuillier , and the financial support of the swiss national fund and manep ( v.n.k . and f.m . ) are gratefully acknowledged . here we present the expressions for the spin operators for magnetic field in the @xmath56 direction . the two ground state wave - functions @xmath149 are modified in the following way in the presence of dm interactions ( @xmath150 , @xmath151 ) : @xmath152 \nonumber \\ & & + \frac{\sqrt{6 } \tilde{d } \tilde{h}}{4 } \left[|p_x\rangle + |p_y\rangle -|q_x\rangle + |q_y\rangle \right ] , \nonumber \\ \frac{i\tilde{d}}{2\sqrt{2}}\left[|p_x\rangle + |p_y\rangle + |q_x\rangle -|q_y\rangle \right ] + i \tilde{d } |t_z\rangle \nonumber\\ & & + \frac{\tilde{d } \tilde{h}}{2\sqrt{2 } } \left[-|p_x\rangle + |p_y\rangle + |q_x\rangle + |q_y\rangle \right],\end{aligned}\ ] ] where @xmath153 , @xmath154 are the three excited triplet states on a tetrahedron . from these equations we obtain @xmath155 we also give the ground state energy splitting on a single tetrahedron , in ( weak ) external magnetic field with arbitrary direction @xmath156 from here the effective magnetic field " @xmath91 appearing in the pseudospin hamiltonian ( 10 ) is : @xmath157 . we briefly discuss the structure and treatment of the term @xmath97 in ( 10 ) . as is clear from ( 7 ) and ( a2 ) , potentially contributions of two types appear : ( a. ) terms of order @xmath158 , and ( b. ) terms of order @xmath159 . while treating these terms we will assume that the unit cell structure of fig . 2(a ) does not change . indeed , since we are interested in the case of weak fields @xmath160 , the above coupling constants are of sub - leading order with respect to the case without a field , and therefore one does not expect the unit cell to change . under this assumption we find that the terms of order @xmath158 vanish identically for the field directions considered in this work . the remaining contribution , e.g. for a field @xmath161 , written ( per site ) within the unit cell of fig . 2(a ) is @xmath162 where @xmath163 these terms were taken in to account in our numerical solution of the mean - field equations corresponding to ( 10 ) . 99 g. misguich and c. lhuillier in _ frustrated spin systems _ , h. t. diep ed . , world - scientific , singapore ( 2003 ) . a. b. harris , a. j. berlinsky , and c. bruder , j. appl . phys . * 69 * , 5200 ( 1991 ) . r. moessner and j. t. chalker , phys . * 80 * , 2929 ( 1998 ) ; b. canals and c. lacroix , _ ibid . _ * 80 * , 2933 ( 1998 ) . h. tsunetsugu , phys . b * 65 * , 024415 ( 2002 ) . o. tchernyshyov , r. moessner , and s. l. sondhi , phys . b * 66 * , 064403 ( 2002 ) . s. e. palmer and j. t. chalker , phys . rev . * 62 * , 488 ( 2000 ) . h. tsunetsugu and y. motome , phys . b * 68 * , 060405(r ) ( 2003 ) ; o. tchernyshyov , phys . rev . lett . * 93 * , 157206 ( 2004 ) . v. n. kotov , m. e. zhitomirsky , m. elhajal , and f. mila , phys . b * 70 * , 214401 ( 2004 ) . our choice of ground states is different from that of ref . leading to different coefficients in @xmath24 . e. berg , e. altman , and a. auerbach , phys . lett . * 90 * , 147204 ( 2003 ) . i. dzyaloshinsky , j. phys . solids * 4 * , 241 ( 1958 ) . t. moriya , phys . rev . * 120 * , 91 ( 1960 ) . m. elhajal , b. canals , r. sunyer , and c. lacroix , phys . b * 71 * , 094420 ( 2005 ) . this work considers the classical limit of the model . r. guida and j. zinn - justin , j. phys . a * 31 * , 8103 ( 1998 ) a. p. ramirez , b. s. shastry , a. hayashi , j. j. krajewski , d. a. huse , and r. j. cava , phys . 89 * , 067202 ( 2002 ) ; o. a. petrenko , m. r. lees , g. balakrishnan , and d. mck paul , phys . b * 70 * , 012402 ( 2004 ) ; o. cepas and b. s. shastry , phys . b * 69 * , 184402 ( 2004 ) . s lee , c. broholm , w. ratcliff , g. gasparovich , q. huang , t. h. kim , and s .- w . cheong , nature * 418 * , 856 ( 2002 ) . o. tchernyshyov , r. moessner , and s. l. sondhi , cond - mat/0408498 .

we show that the s=1/2 pyrochlore lattice with both heisenberg and antisymmetric , dzyaloshinsky - moriya ( dm ) interactions , can order antiferromagnetically into a state with chiral symmetry , dictated by the distribution of the dm interactions . the chiral antiferromagnetic state is characterized by a small staggered magnetic moment induced by the dm interaction . an external magnetic field can also lead to characteristic field - induced ordering patterns , strongly dependent on the field direction , and generally separated by a quantum phase transition from the chiral ordered phase . the phase diagram at finite temperature is also discussed .

based on the fact that computers are commonly used in hospital patient wards and operation theatres , it would be not surprising if they could be contaminated with nosocomial pathogens . cultures taken from the surface of computers keyboards yielded microorganisms such as coagulase - negative staphylococcus ( cns ) ( from 100% of all keyboards ) , diphtheroids ( 80% ) , micrococcus spp . ( 64% ) , methicillin - resistant staphylococcus aureus ( mrsa ; 4% ) , methicillin - sensitive staphylococcus aureus ( mssa ; 4% ) , vancomycin - sensitive enterococcus spp . these studies found all of the tested disinfection solutions were to be effective and compatible for use in disinfecting keyboards . it could be further demonstrated that contamination of the keyboards used by numerous persons was far higher than that seen in keyboards used by only one person . as a consequence to this unavoidable situation , anderson et al . also recommended routine cleaning and disinfection of the work station , especially in situations where keyboard usage involves numerous persons . on an intensive care unit it was discovered that the keyboard keys and mouse input devices of the ward station computers were contaminated up to 5.9% and 6.3% , respectively . interestingly , the telephone handles as well as intercoms were not contaminated due to the fact that they were regularly disinfected . analogously , keyboard keys used by anesthesiologists in the operating room were also shown to be contaminated ( most often with cns and bacillus spp . , but also with mrsa ) . consequent to these findings , a recommendation was made for routine hand disinfection along with daily wipe - disinfection of the computer contact surface . the general consensus from all of the studies examining computer keyboard and mouse devices is unanimous : the decisive preventative measure for the elimination of these infection sources is improved hand hygiene and routine disinfection / cleaning of the pc contact / touch surfaces , , , , , , , , . based upon the fact that most laptops are fitted with a cooling ventilation blower , it was decided to investigate whether the external air inlets into the vent and eventually blown back into the room actually culminates into contamination , thereby spreading potential pathogens into the surrounding area . in order to avoid a mixture of the emission from the laptop together with the surrounding contaminated environmental air , it had to be ascertained that the air exhausted from the laptop would be captured into a microbial air sampler , whereby a secure separation between contaminated room - air and laptop emission could be maintained . the laptops chosen for the study were examined within a laminar air flow safety workbench ( microflow , nunc gmbh , wiesbaden - biebrich ) . for the purpose of this study a box which could be disinfected as well as completely sealed was constructed and placed into the security workbench ( figure 1 ( fig . the suction vent of the microbial air sampler ( air deal 3 p , biomerieux deutschland gmbh , nrtigen ) was precisely positioned onto the opening punched out from the bottom of the box . the top cover of the box could be open in order to place the laptop within ( figure 2 ( fig . further course of the experiment involved the following steps : disinfection of all internal and external surfaces of the box using an alcohol - based surface disinfectant ( terralin liquid ; schlke and mayr gmbh , norderstedt ) possessing microbiocidal and virocidal efficacy ( declared max . effect time against non - sheathed viruses 2 min ) for a minimal duration of 5 minsimultaneous disinfection of the internal surfaces of the workbench with the same liquid solution also for 5 min with the safety workbench switched - ondisinfection of the surface of the microbial air sampler with the same liquid solution for 5 minsurgical , alcohol - based hand disinfection and disinfection of the lower arms according to the declared time of effect for duration of 1.5 min ( ahd 2000 , lysoform , dr . hans rosemann gmbh , berlin ) , sterile op gloves were subsequently put onplacement of the disinfected box into safety workbench , thereafter the box was not movedswitching - off of the safety workbench for the duration of time it took to carefully place the laptops into the box without causing any air - movement or disturbancesswitching - on of the safety workbench for a period of 20 secdisinfection of the gloved handsplacement of the blood agar culture plate into the microbial air sampler , unscrewing the collection head which for the first measurement of the day was initially sterile . for each new subsequent measurement the collection head was disinfected for a duration period of 5 min with a bottled disinfection solution.careful attachment of the microbial air sampler to the opening at the bottom of the box with special attention not to allow any space between the connection ( figure 3 ( fig . 3))switching - on the microbial air sampler for a time period of 5 min in order to determine the blank values ; that is the number of airborne bacteria released into the laminar air flow from the external body of the non - activated laptop removal of the agar plate from the microbial air sampler , disinfection of the collection head and placement of a new agar plateswitching - on the laptop and program start ; as soon as the ventilation fan is activated the microbial air sampler is immediately switched - on once again for a period of 5 min in order to register the air released by the ventilation blowerremoval of the laptop out of the box . disinfection of all internal and external surfaces of the box using an alcohol - based surface disinfectant ( terralin liquid ; schlke and mayr gmbh , norderstedt ) possessing microbiocidal and virocidal efficacy ( declared max . effect time against non - sheathed viruses 2 min ) for a minimal duration of 5 min simultaneous disinfection of the internal surfaces of the workbench with the same liquid solution also for 5 min with the safety workbench switched - on disinfection of the surface of the microbial air sampler with the same liquid solution for 5 min surgical , alcohol - based hand disinfection and disinfection of the lower arms according to the declared time of effect for duration of 1.5 min ( ahd 2000 , lysoform , dr . hans rosemann gmbh , berlin ) , sterile op gloves were subsequently put on placement of the disinfected box into safety workbench , thereafter the box was not moved switching - off of the safety workbench for the duration of time it took to carefully place the laptops into the box without causing any air - movement or disturbances switching - on of the safety workbench for a period of 20 sec disinfection of the gloved hands placement of the blood agar culture plate into the microbial air sampler , unscrewing the collection head which for the first measurement of the day was initially sterile . for each new subsequent measurement the collection head was disinfected for a duration period of 5 min with a bottled disinfection solution . careful attachment of the microbial air sampler to the opening at the bottom of the box with special attention not to allow any space between the connection ( figure 3 ( fig . 3 ) ) switching - on the microbial air sampler for a time period of 5 min in order to determine the blank values ; that is the number of airborne bacteria released into the laminar air flow from the external body of the non - activated laptop removal of the agar plate from the microbial air sampler , disinfection of the collection head and placement of a new agar plate switching - on the laptop and program start ; as soon as the ventilation fan is activated the microbial air sampler is immediately switched - on once again for a period of 5 min in order to register the air released by the ventilation blower removal of the laptop out of the box . in parallel , a smear was taken using cotton swabs at the site of the laptop exhaust vent where the cooled air is blown out . mller gmbh , eppelheim ) , subsequently placed into a casein - sojapepton - solution and vortexed . after 24 hr incubation of the csl , 50 l fractionated were spread onto columbia blood agar . the cultivated colonies derived from the collected air as well as those from the smear were biochemically differentiated in the same manner as those from enrichment cultures . the devices originated from a total of 7 different manufacturers and were drafted for use from various hospital stations without prior notice or disinfection ( table 1 ( tab . temperature pictures were performed at the blower exhaust vent and within the interior of the laptop using a thermo camera variocam high resolution ( infra tec gmbh dresden ) . for this the housing of the laptops were opened . in order to achieve a defined cpu - burden and the associated warmth development the software stress my pc the pre - values derived from the air circulated around the casing of the laptop stood at 40.117.9 colony forming units per m ( cfu / m ) ( table 2 ( tab . this was also found to be the case with molds whereby the factor was increased by only 1.2 ( 5.79.46 vs. 7.114.90 ) . with the exception of the aerobic sporulation , there was no differentiation observed between the blank values and the running blowers in terms of species distribution . in the case of the apathogenic sporulators , the figures were doubled from 4.86.1 cfu / m to 11.113.2 cfu / m whereby , however , this difference was not considered significant ( wilcoxon signed rank - test , p=0.211 ) . the spectrum of the freely released microorganisms encompassed mostly members of the localized flora of the skin ( coagulase - negative staphylococcus and micrococcus luteus ) , lacking pathogenic potential and therefore only capable of contaminating the body surface . from 2 laptops were 4 cfu of methicillin sensitive staphylococcus aureus released but each time only for the blank values ( laptops 2 & 12 ) . 1 laptop released 2 cfu of -hemolyzing streptococcus but in this case only after the blower was switched - on . a correlation between origin of the laptop , the manufacturer , the amount of freely - released germs as well as germ spectrum could not be developed . swab culture samples taken from the blower exit vents which were directly smeared demonstrated negative growth in 16 of the cases . the remaining 4 showed only members of the localized flora of the skin and/or aerobic spores . even following applied enrichment , 6 of the smears remained negative and the germ spectrum did not alter ( table 3 ( tab . the results were found to be so uniform that it was decided not to match the results to the specific laptop manufacturers . at the site of the blower exit vent of a laptop model travelmate 3000 following 10 min of running the software at maximum , measured temperature 56.4c ( figure 4 ( fig . 4 ) ) . suctioned cool air flowing over the internal surface of the laptop achieved a measured temperature of 73.2c ( figure 5 ( fig . the results of this study allow the assumption that the activated blowers within the investigated laptops did not result in an additional release of nosocomial pathogens into the surrounding environment . the exit vent of the blower was also not contaminated with nosocomial germs . due to the high temperatures in the inner parts of the laptop ( up to 73c ) , a biofilm could not be created within the blower space or surrounding surfaces from which the risk of disease activators could be emitted . even at the site of the blower vent the fact that spores were released with or without the activated blower leads to the assumption that they originated from the external surface of the laptop and perhaps from the air shaft of the blower . that spores and molds possess a high persistence against dry heat than vegetative bacteria ; it is possible that they could survive a short term within the airspace of the blower . this is , however , unlikely for nosocomial vegetative bacteria due to an intolerance of general temperatures 60c . before the point is reached where the processor has become heated - up and the blower is activated , the surrounding room air is sucked into the device . the air becomes immediately warm and dry , whereby bacteria have no possibility of clinging to the inner surface of the blower , reproducing and eventually building a biofilm . the explanation for this is that most disease activators are mesophilic ; meaning that they proliferate preferably at temperatures between 1545c and for the construction of biofilm require water in order to develop a completely hydrated eps - matrix . interpretation of the findings is thereby supported in that direct smears obtained from the airflow ventilated inner surface of the laptop were without exception negative . once the remaining warm air within the airspace of the blower is cooled after the laptop has been switched - off , it is possible through volume traction that contaminated external air finds its way into the blower compartment . that room air within ward stations is minimally burdened in a microbial sense ( e.g. 200400 cfu / m in a patient room and hall of an icu ward , it can be calculated that after a room air backflow of approximately 2 cm , the number of germs which had entered clearly stood at 1 cfu . even though the cooling blower was turned - off the conditions for biofilm development were not present .

inadequately performed hand hygiene and non - disinfected surfaces are two reasons why the keys and mouse - buttons of laptops could be sources of microbial contamination resulting consequently in indirect transmission of potential pathogens and nosocomial infections . until now the question has not been addressed whether the ventilation - blowers in laptops are actually responsible for the spreading of nosocomial pathogens . therefore , an investigational experimental model was developed which was capable of differentiating between the microorganisms originating from the external surfaces of the laptop , and from those being blown out via the ventilation - blower duct . culture samples were taken at the site of the external exhaust vent and temperature controls were collected through the use of a thermo - camera at the site of the blower exhaust vent as well as from surfaces which were directly exposed to the cooling ventilation air projected by the laptop . control of 20 laptops yielded no evidence of microbial emission originating from the internal compartment following switching - on of the ventilation blower . cultures obtained at the site of the blower exhaust vent also showed no evidence of nosocomial potential . high internal temperatures on the inner surfaces of the laptops ( up to 73c ) as well as those documented at the site of the blower exhaust vent ( up to 56c ) might be responsible for these findings .

On Wednesday night on CBS, after 33 years as a host, the longest late-night tenure ever, Mr. Letterman will close out his career with his 6,028th episode. His influence has been substantial: He breathed new life into the talk show, taking it beyond the traditional desk-and-sofa interview sessions with an array of innovative, often outlandish antics; he gave birth to many careers; he became a role model for a generation of comedians, including most of the current late-night roster; and he turned signature segments like Stupid Pet Tricks and his Top 10 list into American cultural institutions. He was also front and center for memorable noncomedic moments, whether hosting the first late-night show after the Sept. 11 attacks, turning his 2000 heart surgery into a narrative on his show or castigating John McCain after he canceled an appearance before the 2008 presidential election. Mr. Letterman lived out some dark moments on his show as well. In the mid-1990s, after his ratings began to slide, his well-known tendency to self-flagellate turned nearly literal one night when he viciously beat up a David Letterman dummy on stage. In 2009, in one of television’s most uncomfortable moments, he acknowledged that he had had sex with female staff members. He could be a brusque interviewer who sometimes made his guests squirm. He was fiercely private, rarely giving interviews, and his disdain for the politics of show business played a role in his failure to land the dream job he had long coveted: succeeding Johnny Carson as the host of “The Tonight Show” in 1992. In an unusually public competition for the job, Mr. Letterman lost out to Jay Leno, and he spent most of the next two decades trailing Mr. Leno in the ratings. ||||| David Letterman introduces Bill Murray during Tuesday's episode of 'The Late Show.' [CBS] Bill Murray made one more memorable entrance on Tuesday for his appearance on David Letterman’s Late Show — the last one before Letterman signs off on Wednesday night. We won’t spoil exactly how the comedian took to the stage — the video is posted below — but the two did share a hug as Murray arrived, before the Groundhog Day and Lost in Translation star made his way to mingle with both audience members and Letterman’s band. CNN reported that, according to witnesses, Tuesday’s episode will also feature appearances by Regis Philbin and Rupert Jee. Jee, who owns the diner next to the Manhattan Theater, is reportedly the subject of a retrospective on his best moments on the show. The on-air association between Murray and Letterman spans the majority of Letterman’s time in the spotlight; Murray was the first guest on both the Indiana native’s Late Night show on NBC and his CBS run on The Late Show. Watch an excerpt from Murray and Letterman’s last Late Show appearance, as posted by CBS on Tuesday, below. Murray’s first TV interview with Letterman is also online, and can be seen below. ||||| IDEAS Merrill Markoe was the co-creator and original head writer of “Late Night With David Letterman.” On this, the eve of the finale of a show I had a hand in creating, I have been repeatedly asked to offer a few thoughts. Toward that end, I have compiled the following group of clips. All of them are from shows you probably haven’t seen in a long time, if you ever saw them at all. They are from the early ‘80s when “Late Night With David Letterman” was on NBC. As you may know, when Dave switched networks in ’93, NBC locked it’s version of the shows in a vault deep in the bowels of Area 51, just catty corner to where the U.S. government hides its photographic proof of UFOs. They were meant to remain there until the end of time, but that was before YouTube was created, in 2005, and the end of time just kind of came and went. Before you start clicking on the links, I feel obligated to warn you that these are NOT the most-loved or most-requested clips on anyone’s list but my own. They have been selected for only two reasons: 1. because they contain moments I have thought of repeatedly over the years, sometimes with giddy amazement, and 2. I was able to find them online. Some of them I had no hand in creating. Some of them I did. A few of them I can’t believe we got on the air. All of them were brought to life with the help of a great staff full of talented people who got the joke and played along accordingly. A final word before we begin: These clips vary in quality. Some were videotaped by fans on their home VCR equipment. To increase your enjoyment, it may be necessary to pretend that you actually prefer watching blurry images and listening to uneven sound. 1. This first clip is from the “The David Letterman Show,” a LIVE NBC morning show that lasted 19 weeks with me as its head writer. During its run, we created the DNA used to launch the first incarnation of Dave’s late night show. However, the creative credit for this clip belongs entirely to the fevered brain of Andy Kaufman who somehow manages, in the space of under eight minutes, to willfully break every unwritten rule and expectation for a talk-show guest. After opening with an anecdote about his floundering career, during which he seems to be begging the host for sympathy, he repeatedly reprimands the audience for laughing at him and displays symptoms of a lingering cough. The bit ends with Andy heading into the audience to try and collect some spare change. Its all so very very wrong that the mere thought of it has been making me laugh for 35 years.(For bonus points, I am in this clip standing by the studio door.) 2. The afore mentioned morning show provided quite a few moments that were so surreal I sometimes think I’m making them up. Chief among them was the time that we devoted a big part of the show to an elaborate 50th wedding anniversary party for Sam and Betty Kotinoff, a couple from Long Island who had written us a letter. Because the party details were arranged by a flamboyant caterer, it was meant to hit a high point when sparklers were lit and synthetic rose petals dropped from the ceiling. Unfortunately, when the rose petals hit the sparklers, chemistry took over, and they immediately transformed into little flaming puddles of plastic. Small fires broke out. The Kotinoffs began subtly stamping them out with their shoes. Soon, stage hands stepped in with fire extinguishers. But the always witty and cool-headed Hal Gurnee, the show’s director, brought in a handheld camera to capture it all in an artistic low-angle shot. Meanwhile, Dave just continued announcing who the guests would be tomorrow as a wedding singer, stationed behind him, crooned “Can’t Smile without You.” It was as close to being on the set of a Fellini movie as I have ever come. After the show ended, Dave was very upset about the possible repercussions of setting a network show on fire. Gravely we went into his office to watch the incriminating footage. However when we saw how funny it all looked, we began laughing. We continued to break out laughing about it for weeks. Unfortunately I couldn’t find a clip of the Kotinoff party. However I did find another surreal morning-show clip. Obviously taped by a fan, it is the last segment of the very last morning show before cancellation. We had only one more day to do the show, and we were still LIVE. So throughout the broadcast we showed the pictures and resumes of all of the newly unemployed staff members. Then in the final moments, Harve Mann, a singer we had previously hired to sing special lyrics written for show’s theme, serenades the audience with some new lyrics we worked on that morning about the show that would replace us: “Las Vegas Gambit.” Staff members, dressed as the playing cards that would be part of that new game show, danced around the set. I don’t think anyone will argue with me when I say that a more deranged or goofily hostile piece of video has ever aired on a network in the name of pleasant morning entertainment. 3. “The Dubbed Show” was an idea by the brilliant Randy Cohen who decided to try to bring something new to a standard re-run. The show remains the same in all respects except one: It contains a perfectly synched new audio track dubbed by the people who dub foreign movies into English. To make this happen, Randy painstakingly created a script of the original show to give to professional voice-over actors who would dub it from English into other English. Watching Dave and his guests say the same things, only in slightly different voices, made me question everything I ever knew to be true in the universe. What you are about to see is Dave and Sandra Bernhard vocally dubbed by others. 4. Everything about Chris Elliott’s unique and idiosyncratic contributions to the show have always made me laugh. We hired Chris when he was about 21 and employed as a tour guide at Rockefeller Center. It didn’t take him long to start making appearances on the show as a variety of “characters” that he wrote for himself. “The Guy Under the Seats,” who came up through a trap door in the floor of the aisle in the audience, was the first of many. All of them were so hilarious that I almost chose the one below at random, but a Google search will allow you to inspect the rest of them. Here is the introductory appearance of a character he created for a week of shows we taped in Los Angeles. Chris called this one “The Laid Back Guy.” 5. “They Took My Show Away” was an “educational film” written by the reliably hilarious Tom Gammill and Max Pross. In it, Dave explains the frightening and sometimes cruel realities of show cancellation to a sad and confused little boy. 6. I had the idea of doing a Late Night “anthem” because at that particular moment in the ’80s I noticed a proliferation of a certain kind of heart-tugging montage in advertising. These ads were always a combination of warm family moments and nature scenes set to a poignant yet uplifting emotional piece of music. Not until a logo appeared at the very end was there any way to tell if what they were selling was a bank, a phone company, a cake mix, a soft drink, or a television series. So writer Jeff Martin and I assembled an anthem for the show we called “Late Night World of Love.” The multi-ethnic chorus of children was a nod to all the “We are the World” knocks-offs that also seemed to be everywhere at the time. 7. “New Catch Phrases” is another idea that started with me but went on to be group written by everyone. Once again it was a take on advertising and television in our culture and the way certain frequently repeated slogans make their way into every day life. At the time everyone seemed to be quoting a commercial that starred an old lady who looked into the camera and said “Where’s the beef?” So we decided to try to start a catch phrase, all by itself and let an audience vote for their favorite. After the winning entry, “They pelted us with rocks and garbage” (contributed by Matt Wickline) was selected, the show spent the rest of the week working out ways to include it and hopefully help it gain traction. I still have a shirt and a button that someone sent us. 8. Every now and then, in the middle of the night, “Chinese Restaurant College Bowl” comes to me like a strange hallucination. It owns a place in my heart for its sheer labyrinthine craziness. Assembled by Tom Gammill, Max Pross and myself, it started out as an idea about staging unusual reunions. We planned to go up to random people as they stepped out of an elevator, get all of their names and phone numbers, and then reunite the whole elevator on the air. It ended up being about two Chinese restaurants that we had seen somewhere in New York City that both had names that sounded like colleges. One was called Hunan Wok University, because it was on University Avenue. The other was called Szechuan State, because it was on State street. From there it morphed into bringing customers from each of the restaurants on to the show to play College Bowl and answer questions about the respective restaurant menus. Having decided on that, we felt we needed to add a tour of the two campuses and a Chinese food delivery race between the two restaurant competitors. And so we did. 9. “Dog Poetry” was something I wrote and directed when we had a little free time with the crew at the end of a remote. In it, my dog Stan recites a poem to summer. It also contains a track of Stan’s noises that I tried to synch with the subtitles. After it was finished, it went unaired for quite a while. Dave was very ambivalent. He didn’t think it would get laughs. I finally weaseled it onto the show by creating a segment called “Pieces that will never be on the show,” where I grouped it with other things that had never aired. To my enormous relief, it played really well. All these years later people still come up to me and repeat the line “My empty dish mocks me.” Weirder still, I think “Dog Poetry” might be at ground zero for dog videos. The Internet didn’t hit for another 15 years. Not everyone with a dog had access to film production the way they do now. There are a million other funny little moments for which no video clips can be found online. From time to time I think of the incredibly peculiar objects we had made to order for an assortment of comedy pieces we referred to as “wacky props.” To create these, we commonly paged through the mail-order catalogs of the time, finding inspiration in their approach to merchandizing and copy writing. Sometimes the results appeared on the show as “New Gift Ideas.” Sometimes we grouped them into something more seasonal or topical. Kathleen Ankers, who appeared on the show as the Bookmobile lady, ran the art department and would patiently find a way to manufacture a decent working version of whatever it was we requested. Of the hundreds of crazy things I saw her make, some of the ones that have stayed with me were by the always brilliant George Meyer. A few times a year, I think fondly of “The Giant Doorknob,” George’s take on what is for sale in “joke catalogs.” The copy George wrote for it still makes me laugh. “In Mexico it’s El Knob Grande. Here in the U.S. we call it the giant phony doorknob and it’s a panic. This over-sized jumbo knob is much larger than it oughta be. In fact, its just plain big! Simply attach it to an ordinary door and then wait for the fireworks. Your friends will flip when they see for themselves how truly big a doorknob can be.” I also think frequently of Andy Breckman’s “Perpetual Birthday Card” which read “Happy Birthday today and on this day every year for the rest of your life.” Merrill Markoe Contact us at [email protected]. ||||| Oprah makes her last appearance on “The Late Show.” (Jeffrey R. Staab/CBS) It’s no secret that not everyone got along with David Letterman, who has a famously prickly personality. Over his 33 years on late-night TV, he managed to make a lot of his guests pretty angry. Then again, he was also delightful to many. Here are some of his friends, enemies and frenemies through the years. [David Letterman taught us to ward off celebrity stupidity. But stupidity won.] FRIENDS * Regis Philbin Oh, these two. Philbin holds the title for the most appearances ever on Letterman’s late-night shows, as he’s stopped by 136 times over the years. Reege also filled in as guest-host when Letterman had to step off the air for his heart surgery in 2000. * Zsa Zsa Gabor You’ll only go on a fast-food road trip with someone you really like. * Steve Martin/Tom Hanks/Howard Stern/Bill Murray We group these four together because their interviews seem pretty similar — Letterman is always delighted to chat with other guys who have been around forever. * Isabella Rossellini Letterman has always been a fan — remember when he asked her out on a date? * Denzel Washington The star has been on the show tons of times and Letterman loves putting him in weird situations: On stage with Don Rickles; telling vacation stories with Lenny Kravitz; trying to start a bromance; or being in front of an empty stage during Hurricane Sandy. * Jennifer Lawrence He won’t bring a comforter into the freezing studio for just anyone. [Stephanie Birkitt has been written out of Letterman’s ‘Late Show’ history, and it’s a damned shame] ENEMIES * Cher We all know she didn’t hold back during this contentious interview. * Bill O’Reilly Letterman got actually quite angry during their 2006 talk about the Iraq War. * Madonna Dropping 14 f-bombs in one interview certainly made her an enemy of the network, at least. * Justin Bieber He’s just such an easy target. FRENEMIES * Oprah While they did indeed have quite the awkward interview in the ’90s, talk of their feud may have been a bit exaggerated — by now, they’re actually real friends. * Lindsay Lohan Letterman gives her a hard time, but we suspect he has a soft spot for the troubled star. * John McCain Never cancel on Letterman with a fake excuse; you will get called out on television. Sen. McCain eventually made up for his blunder by appearing on the show (and apologizing) a few weeks later. READ MORE: David Letterman retires: Here’s the most important thing that happened to him every year of his career Some of Letterman’s best moments through the years Top 10 parenting lessons I learned from David Letterman Letterman’s retirement signals a possible generational shift for late-night TV Here’s what happened the moment David Letterman announced his retirement David Letterman: 2012 Kennedy Center Honors profile GALLERY: David Letterman’s late shows ||||| Photos: Memorable 'Late Show' moments Even when CBS' "Late Show with David Letterman" veers into awkward, uncomfortable territory for the guest -- as it often does -- Letterman never loses his cool. In fact, the opposite happens: The show only gets better. As the show winds toward its May 20 conclusion, here are some memorable moments. Hide Caption 1 of 20 Photos: Memorable 'Late Show' moments Passing of the torch – Any moment with legend Johnny Carson and legend-in-the-making Letterman was destined to be a classic, but Carson's appearance on the "Late Show" in May 1994 is the most memorable. The former "Tonight Show" host opted to make his last TV showing with Letterman, who appropriately handed over his desk chair to his idol. Hide Caption 2 of 20 Photos: Memorable 'Late Show' moments Tribute to Johnny Carson – After Carson died in January 2005, David Letterman paid tribute to him in the best way he knew: by turning over his entire monologue to the celebrated comedian and TV personality, composing it of jokes Carson had written. Hide Caption 3 of 20 Photos: Memorable 'Late Show' moments Madonna's F-bombs – In March 1994, Madonna severely tested Letterman's mettle in an exchange that's become a standout late night moment. Letterman introduced Madge as a top-selling pop star who'd slept with some of the biggest names in the industry, which prompted Madonna to go off a very profane deep end. At last count, somewhere around 13 F-bombs were dropped over the course of the interview. Hide Caption 4 of 20 Photos: Memorable 'Late Show' moments Drew Barrymore flashes Dave – When Drew Barrymore showed up on "Letterman" in 1995, she came bearing gifts -- of a sort. The then-20-year-old actress was a ball of "good energy," and when talk turned to her interest in "nude performance dance," Letterman of course had to get a preview -- complete with flashing. It was his birthday, after all. Hide Caption 5 of 20 Photos: Memorable 'Late Show' moments Courtney Love channels Drew Barrymore – In March 2004, Courtney Love tried to pull off what Drew Barrymore had adorably done a decade earlier. Unfortunately, Love's would-be teasing reveal turned into a major -- and memorable -- fumble. Hide Caption 6 of 20 Photos: Memorable 'Late Show' moments First broadcast after 9/11 – Letterman's first show after the September 11 attacks was an understandably subdued and emotional episode. The monologue was skipped in favor of honoring those lost in the attack. Dan Rather was one of the night's guests, and he memorably couldn't hold back tears as he recited "America the Beautiful." Hide Caption 7 of 20 Photos: Memorable 'Late Show' moments Honoring Warren Zevon – In the fall of 2002, Letterman showed his graciousness and tender heart when he dedicated an entire episode to the terminally ill Warren Zevon in a celebration of his music. The singer-songwriter passed away the following year. Hide Caption 8 of 20 Photos: Memorable 'Late Show' moments McCartney performs – Musician Paul McCartney took over the marquee of the Ed Sullivan Theater, where the Beatles made big news in 1964, to performs for the '"Late Show" on July 15, 2009. Hide Caption 9 of 20 Photos: Memorable 'Late Show' moments Dave and Oprah bury the hatchet – It had been 16 years since Oprah Winfrey last set foot on "Letterman" when she finally returned in December 2005. The episode of course brought in monster ratings, as it appeared that the two were making up. The irony was that neither truly knew -- or at least would admit on TV -- what caused their supposed "feud," or if there was ever a tiff in the first place. Hide Caption 10 of 20 Photos: Memorable 'Late Show' moments Michael Richards' mea culpa – When you need to make a massive apology, it makes sense to turn to the well-respected Letterman to help you out. That's what "Seinfeld's" Michael Richards ended up doing in November 2006, with help from Letterman's guest of the night, Jerry Seinfeld. Richards, however, wasn't in the studio -- he made his apology via satellite after coming under fire for using the N-word during a tirade at a comedy club. "Awkward" doesn't begin to describe the appearance. Hide Caption 11 of 20 Photos: Memorable 'Late Show' moments Dave and Bill O'Reilly call a truce – Before Bill O'Reilly and David Letterman found a reason to high-five one another in 2011, they'd had a war of words while taping "Late Show" in 2006. The conversation was about the Iraq War, and the debate became so agitated that the light-hearted comments turned into terse insults. Hide Caption 12 of 20 Photos: Memorable 'Late Show' moments Paris Hilton gets grilled – Paris Hilton braved seeing Letterman again in 2008 even after he upset her during her 2007 interview. The late night host grilled her about her jail time to the point that she said she was "sad" she'd even come on the show. The following year, Letterman acknowledged how tough he'd been on the celebutante and made nice Hide Caption 13 of 20 Photos: Memorable 'Late Show' moments John McCain in the hot seat – After initially trying to skip out on Letterman's show in 2008, John McCain finally made it into the hot seat that October. The politician was faced with chatting up a man who roasted him for his cancellation in an earlier monologue. Both moments were deliciously squirmy TV Hide Caption 14 of 20 Photos: Memorable 'Late Show' moments Joaquin Phoenix's strange act – Watching Joaquin Phoenix appear on "Letterman" in 2009 was like watching a train wreck -- it was so hard to watch, but you just couldn't look away. Phoenix had drastically altered his appearance and behaved strangely, as Letterman tried to figure out how to navigate the puzzle before him. It was all an act, though, and Phoenix returned to the show in 2010 to apologize. Hide Caption 15 of 20 Photos: Memorable 'Late Show' moments Dave's shocking confession – In October 2009, Letterman made a stunning admission live on the air when he told his audience that he'd had sexual relationships with female members of his staff and that someone had been attempting to blackmail him as a result. The following Monday, he used his show to offer a "heartfelt" apology to his wife and to his female staffers. Hide Caption 16 of 20 Photos: Memorable 'Late Show' moments Richard Simmons goes up in smoke – Richard Simmons and David Letterman have a wonderfully antagonistic friendship, and out of the many times the fitness king has appeared on the program, it's hard to pick a favorite. This moment from 2009, when Simmons and Letterman bickered over how to use a food steamer just before it burst into flames, is the kind of late night gold that other hosts dream about. Hide Caption 17 of 20 Photos: Memorable 'Late Show' moments Dave and Jay Leno team up – Letterman isn't above poking some friendly fun at his rival, Jay Leno, and in the disastrous NBC late night wars of 2010, Letterman kicked it up a notch . But, we assume, it was all in good fun -- Letterman still joined Oprah Winfrey and Leno in a "Late Show" promo during the Super Bowl that year, an ad that was said to be Letterman's idea. Hide Caption 18 of 20 Photos: Memorable 'Late Show' moments Lindsay Lohan gets emotional – Prior to her court-mandated stint in rehab, Lindsay Lohan gave an emotional but also surprisingly endearing and transparent interview. Letterman, of course, didn't take the easy route and asked pointed, frank questions. Although he led her down a road that ended in tears, the host commended Lohan when it was done: "We never thought we'd see you again, honestly, because of the jokes and stuff," he told her. "But you have enough spine, enough sense of yourself, enough poise to come out here and talk to me." Hide Caption 19 of 20 ||||| Over the last few weeks, Jimmy Kimmel has done nothing to hide is love for David Letterman. Kimmel wrote Letterman a tribute for TIME and announced that Jimmy Kimmel Live! will air a rerun during Letterman’s final show on Wednesday night. On Tuesday, Kimmel brought his Letterman affection to television, taking more than six minutes bid farewell to the host who shaped his young life. “Even though it looked like every other talk show – it wasn’t. It was totally original, primarily because of the host of the show – who, a lot of time – seemed embarrassed to be there. He was a part of show business,” Kimmel said of his first encounter with Letterman’s Late Night. “He was uncomfortable – he never pretended to be excited, and his way of saying things was so subtle that a lot of the time, the people he was talking to didn’t know he was joking.” It quickly turned into an all-out obsession – his 16th birthday cake was Late Night-themed. He had a Letterman letterman jacket and a L8NITE vanity plate on his first car. “I watched the show every night. I never missed it.” “We had no VCR, so I would have David Letterman viewing parties at my house in the middle of the night,” he said. “And little did I know that many years – and many pounds later – that watching that show was a great education for me. I learned almost nothing in college – but watching Late Night… not only did I learn how to do everything from Dave. The reason I have this show is because the executives at ABC saw me when I was a guest on Dave’s show – and hired me to host this show.” “We will not have a show on [Wednesday] night – a rerun – but please do not watch it,” he continued. “Especially if you’re a young person who doesn’t understand what all the fuss is about. Dave is the best and you should see him.” Watch the tribute below. frameborder=”0” allowFullScreen> Keep up with all the latest late-night coverage by subscribing to our newsletter. Head here for more details. ||||| Since 1982, David Letterman has paved the way for dozens of comedians who've transformed the landscape of late-night television and comedy in general. Between Late Night on NBC and his current Late Show on CBS, many of Letterman's writers and employees have advanced to create amazing comedy of their own, largely owing their starts to Letterman. The roster includes writers like Merrill Markoe, who helped create Letterman's Late Night show, to Louis C.K., who became an icon in his own right. Letterman's final show airs May 20 on CBS. Before he says goodbye, take a look at some hilarious and legendary comedians who were once his humble employees. 1. Chris Elliott Elliott, a writer and frequent performer for Letterman on both the NBC and CBS late-night shows, made a huge splash with his bizarre character bits, like the one above. Elliott would go on to co-star in films like There's Something About Mary and television shows like Everybody Loves Raymond and Eagleheart. Elliott gave a tearful and perfectly weird sendoff to Letterman on the Feb. 11 show. 2. Merrill Markoe Markoe worked with Letterman before his foray on late night, writing for the short-lived morning talkshow, The David Letterman Show in 1980. She went on to co-create Late Night for NBC, where she became head writer. Markoe is considered by many as a pioneer for female television comedy writers. 3. Spike Feresten The longtime Seinfeld writer behind iconic episodes like "The Soup Nazi" began his television comedy career with Late Night in 1990. He went on to host his own talkshow, Talkshow with Spike Feresten from 2006 to 2009. 4. Louis C.K. Image: Brad Barket/Associated Press After writing for Conan's Late Night between 1993 and 1994, C.K. briefly wrote for Letterman's Late Show in 1995. In his FX show Louie, the comedian wrote an arc around his character being considered a potential replacement for Letterman in 2012. 5. Will Forte Image: CBS The SNL alum and current star of Fox's The Last Man on Earth wrote for the Late Show during the 1997-1998 season. Forte occasionally appeared on the show in filmed segments like "Everything's Funnier When Someone Gets Hurt." 6. Dino Stamatopoulos Perhaps best known as "Star-Burns" on Community, Stamatopoulos wrote for the Late Show from 1996-1997. Stamatopoulos has also written for classic shows like Mr. Show and Tom Goes to the Mayor. 7. Jim Downey Image: Universal Downey, who is known as one of the most influential writers in Saturday Night Live history, left the show when Lorne Michaels did in 1980. He worked with Letterman at Late Night as the show's head writer from 1982-1984. You may also know Downey as the furious principal from Billy Madison. 8. Ben Schwartz The screenwriter, actor and Parks and Recreation star actually worked as a page on Letterman's Late Show while performing at Upright Citizen's Brigade in the early 2000s. Through his connections, he was able to freelance jokes for Letterman's monologue, as he detailed in his appearance on the show in January 2015. ||||| Pride before the fall: David Letterman announces his move from NBC to CBS in 1993. (Alex Brandon/AP) He played hard. He played smart. And, by many accounts, he was funnier than the other guy. But when David Letterman leaves late-night TV after his final show Wednesday night, he will leave as an also-ran. No matter how much moral outrage his defenders can muster — no matter how many column inches were filled by writers who said America should like him more — Letterman is the man who couldn’t beat Jay Leno, and sometimes couldn’t beat Leno’s replacement. [Hank Stuever: David Letterman taught us to ward off celebrity stupidity. But stupidity won.] “He was a former weatherman and a failed morning-show host who perfected a sort of snide, irreverent attitude towards showbiz types,” Rolling Stone wrote after Letterman announced his retirement last year. “After getting noticed by Johnny Carson and making a fan out of NBC bigwig Fred Silverman, however, David Letterman found himself taking his goofy antics to a 12:30 a.m. time slot — and thus, a late-night TV legend was born.” On May 20, David Letterman hosted his last show, ending a 33-year career on late-night television. Here are some of his top moments from CBS's "The Late Show with David Letterman" and NBC's "Late Night." (Jayne W. Orenstein/The Washington Post) There was no doubt that the legend was, well, legendary. Letterman feuded with Madonna, tried to engage a nearly mute Joaquin Phoenix and avoided getting in between Andy Kaufman and Jerry Lawler. He invented the “Top 10” list; he invented “Stupid Pet Tricks”; he poked a hole in the absurd, celebrity-fueled gas bag that was late-night television. But there’s this thing about legends: They usually come out on top. Abraham Lincoln didn’t lose the Civil War; B.B. King didn’t step down as the ambassador of blues. Letterman’s panache — his unbridled impertinence — wasn’t enough. People admire the New York Yankees, but not because they lost to the Boston Red Sox in the 2004 American League Championship Series. Perhaps a sense of “shoulda-coulda-woulda” is why Letterman seemed a bit at sea in a recent New York Times look back. “I’m awash in melancholia,” he told the paper of tonight’s exit. “Over the weekend, I was talking to my son, and I said, ‘Harry, we’ve done like over 6,000 shows.’ And he said, [high-pitched child’s voice] ‘That’s creepy.’ And I thought, well, in a way, he’s right. It is creepy.” “It is creepy”: Not exactly the note any showman should want to go out with while comparing retirement to “a good, solid punch to the head.” Contrast this to Leno’s first act after he retired the first time: He stole back his own show from Conan O’Brien and, after his second retirement, won a Mark Twain prize and leaped back on to the stand-up comedy circuit. 1 of 31 Full Screen Autoplay Close Skip Ad × David Letterman says good night to late night View Photos The comedian, a mainstay of the talk-show scene, is retiring after three decades in the spotlight. Caption The comedian, a mainstay of the talk-show scene, is retiring after three decades in the spotlight. A self-deprecating perfectionist, David Letterman, 65, had this to say about being award the Kennedy Center Honors: “I’m thrilled for my family. . . . I’m looking forward to it. But please. . . . I want people to understand: I know it’s not right.” John P. Filo/AP Buy Photo Wait 1 second to continue. [Stand-up guy: Mark Twain Prize recipient Jay Leno returns to his comedy roots] Letterman need not look to Leno to see what spunk looks like, of course. He just needs to look at the 1993 news conference in which he announced his move to CBS. The weatherman from Indiana could have been worried about the big jump to 11:30 p.m. on a new network. Instead, he joked about Amy Fisher before getting down to business. “As some of you may know,” Letterman said, “in the past year and a half, I’ve kinda been interested in doing a show earlier than the one I’m doing now.” Ever the smart aleck, he thanked CBS for its “patience,” “support” and, slyly, “generosity.” (Letterman’s three-year deal was worth $42 million.) For a while after that news conference, Letterman was riding high. He beat Leno in the ratings for a few years; an HBO film portrayed Leno as a bit of a lunk. But then Leno interviewed Hugh Grant on July 10, 1995, beating Letterman for the first time. Leno held on to the lead for much of the next two decades. Thus began Letterman’s very long, very public tenure as second banana. “We prevailed for a while, and then I lost my way a little bit,” Letterman told the Times. “Quite a little bit. And at that point, there was not much I could do about it. People just liked watching his show more than they liked watching my show.” Sounds brutal. Some said it didn’t make a difference: Letterman was loved less than Leno, but loved by those that mattered. “As Leno prepares for his final few Tonight Shows, he finds himself in a unique position: More widely watched than any of his competitors, yet widely reviled by the majority of his peers,” EW wrote last year. So what? After all, Letterman’s shtick did not always play well — his attempt at hosting the Academy Awards ended in disaster, for example. And after he suffered personal setbacks, he retreated from the snark that had made him famous. He took a hiatus for a quintuple bypass in 2000, then brought his doctors on-air to thank them for saving his life. And he fessed up to an extramarital affair in 2009. “I want to be the person I always thought I was and probably was pretending I was,” he told Oprah Winfrey in 2013. “I hurt a lot of people. … I’m not looking to blame anybody. I’m looking to find out why I behaved the way I behaved.” This was the guy who pioneered “Will It Float?” “Now he’s more of the Old Softy,” The Washington Post’s Hank Stuever wrote. “Maybe it was the heart surgery.” When not gushing with gratitude or regret, Letterman could seem petty. Even as the host reached out to Leno for a 2010 Superbowl commercial, he was taking O’Brien’s side in the Leno-O’Brien wars. As ABC 7 explained: “I was delighted by everything that happened — except you losing your job,” Letterman told O’Brien on ‘The Late Show’ in a May 2012 interview, during which both TV hosts did a mock imitation of Leno.” [David Letterman retires: Here’s the most important thing that happened each year of his career] If Letterman wanted to use a 20-year-old feud for laughs or simply remind his audience the feud existed, such comments seemed irrelevant. Late night was already moving on. “Today’s late-night talk shows – viral-culture enterprises comprised of buzz moments and component parts that can be embedded, downloaded, tweeted — are produced with tonight, tomorrow, or anytime audiences in mind,” EW wrote last year. “Letterman helped develop this game too. But he, like Leno, doesn’t play it/never played it as well or with as much interest as his successors.” Sounds like a silver medal is in order. More on Letterman’s final days: Eddie Vedder says goodbye to David Letterman with a broken guitar string Tina Fey removes dress on-air as parting gift ||||| As Letterman sails into the sunset, here’s an ultra-meta roundup of the best, craziest and weirdest commemorations of his historic late night career One of David Letterman’s signature bits on The Late Show is his nightly top 10 list. Since he is leaving the desk for good this Wednesday, writers, wags and other cultural observers have littered the internet with top 10 lists dedicated to Letterman’s best moments on the show. Since Letterman pioneered the meta-commentary of the late night talkshow, we’re going full meta and making a top 10 lists of the top 10 lists about The Late Show. You’re welcome. 1. David Letterman’s 10 most memorable Late Show moments The Hollywood Reporter took the easy route, and compiled a general list of the classics including Joaquin Phoenix’s weird interview, Madonna cursing, Drew Barrymore’s striptease and his post-9/11 return. This is a good general overview. 2. David Letterman’s best sports moments go beyond the top 10 The Washington Post got oddly specific with this list of sports figures’ appearances on the show, including a joint interview with Larry Bird and Magic Johnson, Joe Niekro admitting to cheating and Marv Albert’s sports bloopers. 3. Ten craziest David Letterman interviews Reading is hard, so LiquidGenerationTube (which sounds like an accessory from a Mad Max play set) compiled a video of the 10 craziest interviews so you can actually see Drew Barrymore flashing him or Cher calling him an asshole. 4. The Late Show with David Letterman’s most memorable moments, year by year Comedy blog Splitsider went way beyond the top 10 list and compiled the best moment for each of the 22 years that Letterman was on The Late Show. There are a lot of the usual suspects, but also clips of Letterman working at McDonald’s, a young Jon Stewart finding out his talkshow has been canceled and a scary story about bears. 5. David Letterman’s best food moments Sure, Letterman had plenty of people cooking on his show, but only Yahoo thought up the idea to compile a list of those celebrities who have grilled, shucked and boiled with the host, including Martha Stewart (duh), Julia Child, Tom Cruise and, yes, Liberace. This list gets weirder and weirder. 6. Let us now praise the gap-toothed god of late night GQ really did it right and had 10 of Letterman’s regular guests choose their favorite moments so we don’t have to guess which segments Amy Sedaris, Tina Fey, Jimmy Kimmel or Paul Rudd loved the most. 7. 11 of Bill Murray’s Greatest Letterman Appearances Bill Murray was The Late Show’s first guest and he will be its last – and he’s made a bunch of stops in between. Mental Floss (apparently too indecisive to get with the program and limit their list to 10) has chosen 11 of his most memorable and ridiculous guest spots. 8. Top 10 disastrous Letterman interviews Since you can’t have the great without the horrible, Time magazine compiled the show’s 10 worst interviews, including Kristen Stewart thinking she can drive from London to Russia, Michael Richards’ ineffective apology and Crispin Glover trying to kick Dave. 9. Relive the top 10 flirtatious moments between Julia Roberts and Dave Letterman Just look at this headline from People. There is no top 10 list more specific than this. Not only are they top 10 moments, but those moments have to be flirtatious and they have to be only between Julia Roberts and David Letterman. And we can’t just watch them, we have to relive them. What if we never lived them in the first place? Can we no longer participate in this article? Probably not. 10. Are these David Letterman’s top 10 top 10 lists? The only way we could end this top 10 list of top 10 lists is with another top 10 list of top 10 lists. However, Adweek seems to be a little bit indecisive about their choices. Doesn’t that kind of defeat the point of a top 10 list? The answer to both of these questions is “I guess so”. ||||| David Letterman has been a fixture of American television for 33 years, beginning his career on Late Night with David Letterman on NBC in 1982. (He moved to CBS and Late Show in 1993.) He’s been hosting late night shows for several decades and more than 6,000 episodes—which may be why it’s easy to forget how innovative the comedian was when he was just starting out. Look back on that very first episode of Late Night, featuring guests Bill Murray and Don Herbert (better known to fans as Mr. Wizard), and you’ll see out-of-the-box segments and improvised moments that helped kick-off what would be his longtime network run—as well as his reputation for trail-blazing. Here are a few standout (colorful, bizarre, and just plain fun) moments from the debut of Late Night, in honor of Letterman’s last late night show: the finale of Late Show, airing May 20 on CBS. The full episode is available below. frameborder=”0” allowFullScreen> The (weird) opening monologue: Like something out of Unsolved Mysteries, or what the Disney employee says before pulling the lever on the Tower of Terror, the opening monologue is a little creepy. “Good evening. Certain NBC executives feel it would be a little unkind to present you this show with just a word of friendly warning. We are about to unfold a show featuring David Letterman; a man of science who sought to create a show after his own image with reckoning upon God. It’s one of the strangest tales ever told. I think it will thrill you. It may shock you; it might even terrify you. So if any of you don’t feel like you care to subject your nerves to the strain, now’s your chance to…well, we’ve warned you.” Everybody wants to know about welding: The (essential) welding shot—Letterman started that trend, everybody. Behind-the-scenes: Letterman guides the camera backstage, from the green room (which doubles as a greenhouse) to the lively control room where a massive Oktoberfest party is well under way. Lesson learned: no control room is complete without accordions and beer steins. In the hot seat with Bill Murray: Bill Murray completely takes hold of his interview, leaving Letterman to throw in the occasional one-liner or play with his pens. But he doesn’t seem that mad about it. Bill Murray gets “Physical”: The actor brings out a crew member for his own rendition of Olivia Newton-John’s “Let’s Get Physical,” complete with jumping jacks and full body convulsions. Will this be re-created for Letterman’s last show? Let’s hope so. “Shame of the City” segment: Letterman takes to the streets for a few interviews with a restaurant worker who pledges to correct a misspelling and a police officer who works in the world’s tiniest “police station.” Letterman in the wild is an unexpected treat. Science with Mr. Wizard: Proving that just about anything could happen on this show, Letterman does some science experiments with Mr. Wizard, one of which includes setting a row of matches on fire. Miraculously, no hair was singed in the making of this segment. For more on Letterman’s departure, check out what Ben Schwartz, Jay Pharoah and more had to say in this retrospective look at the host’s career, as well as Conan O’Brien’s tribute, available here.

– David Letterman has been doing late-night television longer than any other host out there—33 years—and tonight, his 6,028th show, will be his last. In honor of the Late Show host's iconic Top 10 lists, we've compiled the 10 best pieces of Letterman reading out there: "David Letterman, Prickly Late-Night Innovator, Counts Down to His Exit": The New York Times offers a sort of obituary for Letterman's career that answers one question you may not have known you had: Was he friendly with his favorite guests in real life? "I've never seen him outside of the building," says a laughing Julia Roberts, who had great onscreen rapport with Dave during her 26 visits to the show. "The Top 10 List of Top 10 Lists About the Late Show": Yes, lots of outlets are playing off the "Top 10" idea, and the Guardian rounds up the best (including the 10 best times Roberts and Letterman flirted). "David Letterman and Bill Murray Share One Last Late Show Moment": Murray is another one of Dave's memorable repeat guests, and last night he went out with a bang. The Raw Story also has video of Murray's first appearance on the show. "8 Comedians Who Worked for David Letterman Before They Were Big": One of the names on Mashable's list: Louis CK. "Why David Letterman Is Among Television History's Biggest Losers": Not all of the coverage is fawning. The Washington Post highlights Letterman's "very long, very public tenure as second banana." "My Favorite Moments of Late Night With David Letterman": Merrill Markoe, the Late Night writer who created "Stupid Pet Tricks," among other iconic Letterman segments, compiles her list of favorites (with video for all) from the Late Night days in the early 1980s. "Jimmy Kimmel Pays Tribute to David Letterman": Kimmel spent more than six minutes of his show last night honoring Letterman (and he'll continue honoring him by airing a rerun tonight). "David Letterman's Friends, Enemies, and Frenemies Through the Years": WaPo continues its let's-be-honest coverage of Letterman by reminding us of those who didn't get along with the "prickly" host, including sometimes-awkward video. "David Letterman's First Episode of Late Night Was Totally Bizarre (and Fun)": Entertainment Weekly offers highlights from the 1982 episode "that helped kick off ... his reputation for trail-blazing." "How We Freaked Out David Letterman": Penn Jillette offers a behind-the-scenes look at Penn & Teller's ... memorable second appearance on Dave's show. Click for five great tributes to Letterman from other comedians and VIPs.

label - free nanosensors can detect disease markers to provide point - of - care diagnosis that is low - cost , rapid , specific and sensitive.1 - 13 however , detecting these biomarkers in physiological fluid samples is difficult because of problems like biofouling and nonspecific binding , and the resulting need to use purified buffers greatly reduces the clinical relevance of these sensors . here , we overcome this limitation by using distinct components within the sensor to perform purification and detection . a microfluidic purification chip captures multiple biomarkers simultaneously from blood samples and releases them , after washing , into purified buffer for sensing by a silicon nanoribbon detector . this two - stage approach isolates the detector from the complex environment of whole blood , and reduces its minimum required sensitivity by effectively pre - concentrating the biomarkers . we show specific and quantitative detection of two model cancer antigens from a 10 ul sample of whole blood in less than 20 minutes . this study marks the first use of label - free nanosensors with physiologic solutions , positioning this technology for rapid translation to clinical settings .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Federal Employment Reduction Assistance Act of 1996''. SEC. 2. DEFINITIONS. For the purpose of this Act-- (1) the term ``agency'' means an Executive agency (as defined by section 105 of title 5, United States Code), but does not include the Department of Defense, the Central Intelligence Agency, or the General Accounting Office; and (2) the term ``employee'' means an employee (as defined by section 2105 of title 5, United States Code) who-- (A) is employed by an agency; (B) is serving under an appointment without time limitation; and (C) has been currently employed for a continuous period of at least 12 months; but does not include-- (i) a reemployed annuitant under subchapter III of chapter 83 or chapter 84 of title 5, United States Code, or another retirement system for employees of the Government; (ii) an employee having a disability on the basis of which such employee is or would be eligible for disability retirement under the applicable retirement system referred to in clause (i); (iii) an employee who is in receipt of a specific notice of involuntary separation for misconduct or unacceptable performance; (iv) an employee who, upon completing an additional period of service as referred to in section 3(b)(2)(B)(ii) of the Federal Workforce Restructuring Act of 1994 (Public Law 103-226; 108 Stat. 111), would qualify for a voluntary separation incentive payment under section 3 of such Act; (v) an employee who has previously received any voluntary separation incentive payment by the Federal Government under this Act or any other authority and has not repaid such payment; or (vi) an employee covered by statutory reemployment rights who is on transfer to another organization. SEC. 3. AGENCY PLANS; APPROVAL. (a) If the head of an agency determines that, in order to improve the efficiency of operations or to meet anticipated levels of budgetary resources, the number of employees employed by the agency must be reduced, the head of the agency may submit a plan to the Director of the Office of Management and Budget to pay voluntary separation incentives under this Act to employees of the agency who agree to separate from the agency, by retirement or resignation. The plan shall specify the planned employment reductions and the manner in which such reductions will improve operating efficiency or meet anticipated budget levels. The plan shall include a proposed period of time for the payment of voluntary separation incentives by the agency, and a proposed coverage for offers of incentives to agency employees, which may be on the basis of-- (1) any component of the agency; (2) any occupation or levels of an occupation; (3) any geographic location; or (4) any appropriate combination of the factors in paragraphs (1)-(3). (b) The Director of the Office of Management and Budget shall review each plan submitted to the Director under subsection (a) and approve or disapprove such plan, and may make appropriate modifications in the plan with respect to the time period in which voluntary separation incentives may be paid or with respect to the coverage of incentives on the basis of the factors in subsection (a) (1)-(4). SEC. 4. VOLUNTARY SEPARATION INCENTIVE PAYMENTS. (a) In order to receive a voluntary separation incentive payment, an employee must separate from service with the employee's agency voluntarily (whether by retirement or resignation) during the period of time for which the payment of incentives has been authorized for the employee under the agency plan under section 3. An employee's agreement to separate with an incentive payment is binding upon the employee and the agency, unless the employee and the agency mutually agree otherwise. (b) A voluntary separation incentive payment-- (1) shall be paid in a lump sum after the employee's separation; (2) shall be equal to the lesser of-- (A) an amount equal to the amount the employee would be entitled to receive under section 5595(c) of title 5, United States Code (without adjustment for any previous payment made under such section), if the employee were entitled to payment under such section; or (B) if the employee separates-- (i) during fiscal year 1996 or 1997, $25,000; (ii) during fiscal year 1998, $20,000; (iii) during fiscal year 1999, $15,000; or (iv) during fiscal year 2000, $10,000; (3) shall not be a basis for payment, and shall not be included in the computation, of any other type of Government benefit, except that this paragraph shall not apply to unemployment compensation funded in whole or in part with Federal funds; (4) shall not be taken into account in determining the amount of severance pay to which an employee may be entitled under section 5595 of title 5, United States Code, based on any other separation; and (5) shall be paid from the appropriations or funds available for payment of the basic pay of the employee. SEC. 5. EFFECT OF SUBSEQUENT EMPLOYMENT WITH THE GOVERNMENT. (a) An individual who has received a voluntary separation incentive payment under this Act and accepts any employment with the Government of the United States within 5 years after the date of the separation on which the payment is based shall be required to repay, prior to the individual's first day of employment, the entire amount of the incentive payment to the agency that paid the incentive payment. (b)(1) If the employment under subsection (a) is with an Executive agency (as defined by section 105 of title 5, United States Code), the United States Postal Service, or the Postal Rate Commission, the Director of the Office of Personnel Management may, at the request of the head of the agency, waive the repayment if the individual involved possesses unique abilities and is the only qualified applicant available for the position. (2) If the employment under subsection (a) is with an entity in the legislative branch, the head of the entity or the appointing official may waive the repayment if the individual involved possesses unique abilities and is the only qualified applicant available for the position. (3) If the employment under subsection (a) is with the judicial branch, the Director of the Administrative Office of the United States Courts may waive the repayment if the individual applicant available for the position. (c) For the purpose of this section, the term ``employment''-- (1) includes employment of any length or under any type of appointment, but does not include employment that is without compensation; and (2) includes employment under a personal services contract, as defined by the Director of the Office of Personnel Management. SEC. 6. ADDITIONAL AGENCY CONTRIBUTIONS TO THE RETIREMENT FUND. (a) In addition to any other payments which it is required to make under subchapter III of chapter 83 or chapter 84 of title 5, United States Code, an agency shall remit to the Office of Personnel Management for deposit in the Treasury of the United States to the credit of the Civil Service Retirement and Disability Fund an amount equal to 15 percent of the final basic pay of each employee of the agency who is covered under subchapter III of chapter 83 or chapter 84 of title 5 to whom a voluntary separation incentive has been paid under this Act. (b) For the purpose of this section, the term ``final basic pay'', with respect to an employee, means the total amount of basic pay which would be payable for a year of service by such employee, computed using the employee's final rate of basic pay, and, if last serving on other than a full-time basis, with appropriate adjustment therefor. SEC. 7. REDUCTION OF AGENCY EMPLOYMENT LEVELS. (a) Total full-time equivalent employment in each agency shall be reduced by one for each separation of an employee who receives a voluntary separation incentive payment under this Act. The reduction will be calculated by comparing the agency's full-time equivalent employment for the fiscal year in which the voluntary separation payments are made with the actual full-time equivalent employment for the prior fiscal year. (b) The Office of Management and Budget shall monitor all agencies and take any action necessary to ensure that the requirements of this section are met. (c) The President shall take appropriate action to ensure that functions involving more than 10 full-time equivalent employees are not converted to contracts by reason of the enactment of this Act, except in cases in which a cost comparison demonstrates such contracts would be to the advantage of the Government. (d) The provisions of subsections (a) and (c) of this section may be waived upon a determination by the President that-- (1) the existence of a state of war or other national emergency so requires; or (2) the existence of an extraordinary emergency which threatens life, health, safety, property, or the environment so requires. SEC. 8. REPORTS. (a) Each agency which has received approval under section 3 of this Act to pay voluntary separation incentives shall, for each applicable quarter of each fiscal year and not later than 30 days after the date of such quarter, submit to the Office of Personnel Management a report providing-- (1) the number of employees who receive voluntary separation incentives for each type of separation involved; (2) the average amount of the incentives paid; (3) the average grade or pay level of the employees who received incentives; and (4) such other information as the Office may require. (b) No later than March 31st of each fiscal year, the Office of Personnel Management shall submit to the Committee on Governmental Affairs of the Senate and the Committee on Government Reform and Oversight of the House of Representatives a report which, with respect to the preceding fiscal year, shall include-- (1) for each agency which had approval to pay voluntary separation incentives during such preceding fiscal year, and on a combined basis for all such agencies-- (A) the number of employees who received voluntary separation incentives; (B) the average amount of such incentives; and (C) the average grade or pay level of the employees who received incentives; and (2) the number of waivers made under section 5 of this Act in the repayment of voluntary separation incentives, and for each such waiver-- (A) the reasons for the waiver; and (B) the title and grade or pay level of the position filled by each employee to whom the waiver applied. (c) Section 6 of the Federal Workforce Restructuring Act of 1994 (Public Law 103-226; 108 Stat. 111) is amended-- (1) by striking out ``December 31st'' and inserting ``March 31st''; and (2) by striking out paragraphs (1)-(4) and inserting in lieu thereof the following: ``(1) for each agency which paid voluntary separation incentives under section 3 during such preceding fiscal year, and on a combined basis for all such agencies-- ``(A) the number of employees who received voluntary separation incentives; ``(B) the average amount of such incentives; and ``(C) the average grade or pay level of the employees who received incentives; and ``(2) the number of waivers made by each agency or other authority under section 3 or the amendments made by section 8 in the repayment of voluntary separation incentives, and for each such waiver-- ``(A) the reasons for the waiver; and ``(B) the title and grade or pay level of the position filled by each employee to whom the waiver applied.''. SEC. 9. VOLUNTARY PARTICIPATION IN REDUCTIONS IN FORCE. Section 3502(f) of title 5, United States Code, is amended-- (1) in paragraph (1) by striking out ``The Secretary of Defense or the Secretary of a military department'' and inserting in lieu thereof ``Under procedures prescribed by Office of Personnel Management, the head of an agency''; (2) by amending paragraph (3) to read as follows: ``(3) An employee with critical knowledge and skills may not participate in a voluntary release under paragraph (1) if the head of the agency determines that such participation would impair the performance of the agency's mission.''; (3) by striking out paragraph (4); and (4) by redesignating paragraph (5) as paragraph (4), and by amending such paragraph by striking out ``September 30, 1996'' and inserting ``September 30, 2000''. SEC. 10. CONTINUED HEALTH INSURANCE COVERAGE. Section 8905a(d)(4) of title 5, United States Code, is amended-- (1) in subparagraph (A) by striking out ``in or under the Department of Defense''; (2) in subparagraph (B)-- (A) immediately after ``enactment'' by inserting the following ``(or, as applicable, amendment)''; (B) in clause (i) and (ii) each by striking out ``October 1, 1999'' and inserting ``October 1, 2000''; and (C) in clause (ii) by striking out ``February 1, 2000'' and inserting ``February 1, 2001''; and (3) in subparagraph (C) immediately after ``identified'' by inserting ``by the agency''. SEC. 11. REGULATIONS. The Director of the Office of Personnel Management may prescribe any regulations necessary to administer the provisions of this Act. SEC. 12. EFFECTIVE DATE. (a) The provisions of this Act shall take effect on the date of enactment of this Act. (b) No voluntary separation incentive under this Act may be paid based on the separation of an employee after September 30, 2000.

Federal Employment Reduction Assistance Act of 1996 - Authorizes the head of an agency to submit a plan to the Director of the Office of Management and Budget to pay voluntary separation incentives to employees of the agency who agree to separate from the agency by retirement or resignation. (Sec. 4) Provides that a voluntary separation incentive payment be paid in a lump sum after the employee's separation and be equal to the lesser of: (1) the amount the employee would have been entitled to receive (without adjustment for any previous payment); or (2) if the employee separates during a certain fiscal year, according to a specified payment amount for such fiscal year, from FY 1996 through FY 2000. (Sec. 5) Prescribes that an individual who has received a voluntary separation incentive payment and accepts any subsequent employment with the Government within five years after the date of separation shall be required to repay, prior to the first day of employment, the entire amount of the incentive payment to the agency that paid the incentive payment. Provides for waiver of repayment if the individual involved possesses unique abilities and is the only qualified applicant for the position. (Sec. 6) Requires that an agency make a contribution to the Civil Service Retirement and Disability Fund in an amount equal to 15 percent of the final basic pay of each agency employee to whom a voluntary separation incentive has been paid. (Sec. 7) Mandates the reduction of total full-time equivalent employment in each agency by one for each employee receiving a voluntary separation payment. Requires that the President take appropriate action to ensure that functions involving more than ten full-time equivalent employees are not converted to contracts except in cases in which a cost comparison demonstrates that such contracts would be to the advantage of the Government. Provides for the preceding two clauses to be waived upon a determination by the President that the existence of a state of war or other national emergency, or the existence of an extraordinary emergency so requires. (Sec. 8) Mandates certain reports. Makes technical amendments to the Federal Workforce Restructuring Act of 1994. (Sec. 9) Modifies requirements regarding the order of retention in a voluntary participation in a reduction in force. (Sec. 10) Provides for continued health insurance coverage for separated employees.

the first cases of in vitro and in vivo chloroquine resistance in burkina faso were seen in 1983 and 1988 , respectively , and reported clinical failure rates after use of chloroquine for treatment of uncomplicated malaria in children were already around 5% in the early 1990s . more recently , the clinical failure rate of chloroquine in pre - school children was shown to be around 10% in western burkina faso . these findings have led to the conclusion that chloroquine still remains sufficiently effective after many years of resistance occurrence in this part of west africa . little information exists on the dynamics of resistance development towards pyrimethamine - sulfadoxine , the usual second - line treatment choice in african countries with moderate chloroquine resistance . in burkina faso , only very low parasitological and clinical failure rates during use of have been reported in the past . the efficacy of pyrimethamine - sulfadoxine in a rural area of north - western burkina faso is reported . the study took place in six representative villages of the research area of the centre de recherche en sant de nouna ( crsn ) in north - western burkina faso . the nouna area is a dry orchard savanna , populated mainly by subsistence farmers of different ethnic groups . the study was nested into an ongoing insecticide - treated bed net ( itn ) study . all itn cohort children from the six villages visited during a cross - sectional survey in october 2002 were enrolled if they fulfilled the following inclusion criteria : age > 6 months , falciparum malaria ( 37.5c axillary temperature + 2.000 plasmodium falciparum parasites/l blood in the absence of another obvious fever cause ) , absence of antimalarial treatment during previous two weeks , informed oral consent . all study children received a fully supervised single - drug treatment with 1/2 tablet fansidar ( 12.5 mg pyrimethamine plus 250 mg sulfadoxine ) , taken from the essential drug stock of nouna health district . enrolled children were seen daily by village - based field staff over a 14-day period and , in case of fever ( 37.5c axillary temperature ) , blood films were taken . systematic blood slides were taken from all study children on day 0 , 3 , 7 and 14 . blood films were examined by two experienced laboratory technicians of the crsn . for the evaluation of treatment outcome , a modified definition of the who protocol for assessment of therapeutic efficacy of anti - malarial drugs in areas with intense transmission was used . early treatment failure ( etf ) was defined as development of severe malaria on days 13 or axillary temperature 37.5c on day 3 in the presence of parasitaemia , and late treatment failure ( ltf ) as development of severe malaria and/or axillary temperature 37.5c on days 414 in the presence of parasitaemia without previously meeting the criteria of etf . late parasitological failure ( lpf ) was defined as the presence of parasitaemia on day 7 and/or day 14 . approval for the study was granted by the ethical committee of the heidelberg university medical school and the ministry of health in burkina faso . of 357 cohort children seen during the survey , 40 children ( 11% ) were febrile and of those only 4 children had no detectable malaria parasitaemia . overall , 28 children met the inclusion criteria and were enrolled into the study . at baseline , the mean age of these study children was 23 months ( range 932 ) , 17/28 ( 61% ) were male , the mean temperature was 38.1c ( range 37.539.9 ) , and the mean weight was 9.5 kg ( range 5.512.9 ) . the median baseline number of p. falciparum trophozoites was 13.100/l ( range 2.000177.000 ) , and 9/28 ( 32% ) study children had p. falciparum gametocytes on day 0 . no etf was observed and only one ltf occurred in a 26 months old and 10.0 kg weighing male child , who had fever ( 38.7c ) and a low - grade parasitaemia ( 50/l ) on day 14 . in addition , 7/28 ( 25% ) study children still had measurable parasitaemia on day 3 ( 50475/l ) without fever , and 4/28 ( 14% ) study children had a lpf with low - grade parasitaemias ( 75250/l ) , two on day 7 and two on day 14 ( all male ) . on day 7 and/or day 14 , p. falciparum gametozytes were seen in 19/28 ( 68% ) of study children . the findings from this study confirm the still very low level of resistance to pyrimethamine - sulfadoxine in west africa [ 2,7 - 9 ] . the likely reason for the continued efficacy of pyrimethamine - sulfadoxine is the low level of drug pressure in these areas , where the large majority of malaria cases is still treated with chloroquine . these findings justify continued use of pyrimethamine - sulfadoxine for malaria second - line treatment in burkina faso , as in most of west africa . however , the question of which drug or drug combination should be the successor of chloroquine for malaria first - line treatment once this has reached unacceptable high failure rates remains largely unsolved for the poor malaria - endemic countries in sub - saharan africa ( ssa ) . although , with regard to its still high efficacy , pyrimethamine - sulfadoxine would be a promising candidate for replacing chloroquine in west africa , resistance is predicted to occur rapidly when the drug is used alone . artemisinin combination therapy ( act ) is now recommended by the world health organization as a first - line treatment for malaria , but these combinations are comparably very expensive and their use in malaria control programmes will thus not be possible in many countries of ssa without sustainable external support . the combination of amodiaquine and pyrimethamine - sulfadoxine has recently been shown to be even more effective than act , and this combination has now been chosen as a pragmatic interim solution by some countries of ssa . finally , the implications on the long - term effectiveness of intermittent pyrimethamine - sulfadoxine preventive treatment during pregnancy need to be taken seriously into consideration when using pyrimethamine - sulfadoxine as a first - line malaria therapy regimens in ssa . he was responsible for the design of the study , drafted the manuscript and made all necessary corrections . bk was responsible for the overall organisation in burkina faso and contributed to data analysis . the study was funded by the deutsche forschungsgemeinschaft ( sfb 544 , control of tropical infectious diseases ) .

the efficacy of pyrimethamine - sulfadoxine in the treatment of uncomplicated falciparum malaria in young children of a malaria holoendemic area in rural burkina faso is reported . of 28 children treated with a standard single dose of pyrimethamine - sulfadoxine and followed - up over 14 days , only one late treatment failure and four late parasitological failures were observed , all with low - grade parasitaemia . in this area of very restricted use of pyrimethamine - sulfadoxine , the drug appears to be still sufficiently effective in the treatment of malaria . these findings provide further evidence for the justification of continued use of pyrimethamine - sulfadoxine as a second - line treatment for malaria in burkina faso .

SECTION 1. SHORT TITLE. This Act may be cited as the ``National Suicide Hotline Improvement Act of 2018''. SEC. 2. DEFINITIONS. In this Act-- (1) the term ``Commission'' means the Federal Communications Commission; (2) the term ``covered dialing code'' means a simple, easy-to- remember, 3-digit dialing code; and (3) the term ``N11 dialing code'' means an abbreviated dialing code consisting of 3 digits, of which-- (A) the first digit may be any digit other than ``1'' or ``0''; and (B) each of the last 2 digits is ``1''. SEC. 3. STUDIES AND REPORTS. (a) Primary Study.-- (1) In general.--The Commission, in coordination with the Assistant Secretary for Mental Health and Substance Use and the Secretary of Veterans Affairs, shall conduct a study that-- (A) examines the feasibility of designating an N11 dialing code or other covered dialing code to be used for a national suicide prevention and mental health crisis hotline system; and (B) analyzes the effectiveness of the National Suicide Prevention Lifeline as of the date on which the study is initiated, including how well the lifeline is working to address the needs of veterans. (2) Requirements.-- (A) Commission.--In conducting the study under paragraph (1), the Commission shall-- (i) consider-- (I) each of the N11 dialing codes, including the codes that are used for other purposes; and (II) other covered dialing codes; (ii) consult with the North American Numbering Council; and (iii) review the information provided by the Assistant Secretary for Mental Health and Substance Use and the Secretary of Veterans Affairs under subparagraphs (B) and (C), respectively, of this paragraph. (B) SAMHSA study and report to assist commission.--To assist the Commission in conducting the study under paragraph (1), the Assistant Secretary for Mental Health and Substance Use shall analyze and, not later than 180 days after the date of enactment of this Act, report to the Commission on-- (i) the potential impact of the designation of an N11 dialing code, or other covered dialing code, for a suicide prevention and mental health crisis hotline system on-- (I) suicide prevention; (II) crisis services; and (III) other suicide prevention and mental health crisis hotlines, including-- (aa) the National Suicide Prevention Lifeline; and (bb) the Veterans Crisis Line; and (ii) possible recommendations for improving the National Suicide Prevention Lifeline generally, which may include-- (I) increased public education and awareness; and (II) improved infrastructure and operations. (C) VA study and report to assist commission.--To assist the Commission in conducting the study under paragraph (1), the Secretary of Veterans Affairs shall study and, not later than 180 days after the date of enactment of this Act, report to the Commission on how well the National Suicide Prevention Lifeline and the Veterans Crisis Line, as in effect on the date on which the study is initiated, is working to address the needs of veterans. (b) Primary Commission Report.-- (1) In general.--Not later than 1 year after the date of enactment of this Act, the Commission, in coordination with the Assistant Secretary for Mental Health and Substance Use and the Secretary of Veterans Affairs, shall submit a report on the study conducted under subsection (a) that recommends whether a particular N11 dialing code or other covered dialing code should be used for a national suicide prevention and mental health crisis hotline system to-- (A) the Committee on Commerce, Science, and Transportation of the Senate; (B) the Committee on Health, Education, Labor, and Pensions of the Senate; (C) the Committee on Veterans' Affairs of the Senate; (D) the Committee on Energy and Commerce of the House of Representatives; and (E) the Committee on Veterans' Affairs of the House of Representatives. (2) Additional contents.--If the report submitted by the Commission under paragraph (1) recommends that a dialing code should be used, the report shall also-- (A) outline the logistics of designating such a dialing code; (B) estimate the costs associated with designating such a dialing code, including-- (i) the costs incurred by service providers, including-- (I) translation changes in the network; and (II) cell site analysis and reprogramming by wireless carriers; and (ii) the costs incurred by States and localities; (C) provide recommendations for designating such a dialing code; (D) provide a cost-benefit analysis comparing the recommended dialing code with the National Suicide Prevention Lifeline, as in effect on the date on which the report is submitted; and (E) make other recommendations, as appropriate, for improving the National Suicide Prevention Lifeline generally, which may include-- (i) increased public education and awareness; and (ii) improved infrastructure and operations. SEC. 4. NO ADDITIONAL FUNDS AUTHORIZED. No additional funds are authorized to be appropriated to carry out this Act. This Act shall be carried out using amounts otherwise authorized. Speaker of the House of Representatives. Vice President of the United States and President of the Senate.

National Suicide Hotline Improvement Act of 2018 (Sec. 3) This bill requires the Federal Communications Commission (FCC) to coordinate with the Substance Abuse and Mental Health Services Administration (SAMHSA) of the Department of Health and Human Services and the Department of Veterans Affairs (VA) to conduct a study that: (1) examines the feasibility of designating a three-digit dialing code (N11 dialing code) for a national suicide prevention and mental health crisis hotline system; and (2) analyzes the effectiveness of the National Suicide Prevention Lifeline (NSPL) as of the date on which the study is initiated, including how well it addresses the needs of veterans. To assist the FCC in conducting the study, SAMHSA shall analyze and report to the FCC on: (1) the potential impact of such designation of a dialing code on suicide prevention, crisis services, and other suicide prevention and mental health crisis hotlines; and (2) possible recommendations for improving the NSPL generally. The VA shall study and report to the FCC on how well the NSPL and the Veterans Crisis Line are working to address the needs of veterans. The FCC, in coordination with SAMHSA and the VA, shall report on the study to specified congressional committees. (Sec. 4) No additional funds are authorized to carry out this bill.

recent high - resolution and high - cadence observations have revealed a possible rotating motion of prominence barbs around a vertical axis . these have been called barb tornadoes @xcite due to the similarity of the apparent motion of such structures on the limb to terrestrial tornadoes . @xcite reported an event where a prominence shows an apparent rotating motion with velocities of up to @xmath0 . the observation shows cool prominence plasma seen in absorption in the @xmath1 passband of the sdo / aia instrument . the authors argue that the motion is a rotation projected on the solar limb plane . however , such projected motions are also compatible with oscillations and counter - streaming flows , as pointed out by @xcite . more events , up to 201 barb - tornadoes , have been reported by @xcite using aia 171 images . however , these authors studied mainly the morphology of the barbs and deduced a wide range of sizes and lifetimes . @xcite reported doppler shifts using 1083.0 nm triplet data from the german vacuum tower telescope ( vtt ) of the observatorio del teide ( tenerife , spain ) . the observations revealed opposite velocities at the edges of the prominence feet of @xmath2 along a slit placed close to the solar surface suggesting rotation of the cool prominence feet . the width of the feet is about @xmath3 indicating a period of rotation of 4 hours . more recently , @xcite also reported doppler shifts in a prominence pillar using the 195 line of the eis instrument onboard the hinode satellite . the observations revealed a bipolar velocity pattern along the whole vertical prominence pillar . the velocity is almost zero at the tornado axis and increases linearly up to @xmath4 at the two edges of the observed structure . this indicates that also the million - degree plasma related to the tornado - like prominence may be rotating . the euv bands of sdo / aia reveal that the cool plasma seen in absorption moves in consort with the hot plasma . additionally , @xcite , have found evidence of helical magnetic structure simultaneously at two prominence feet . all this evidence suggests that barb tornadoes are rotating vertical structures , nevertheless more observational evidence is needed . the existence of such structures opens new questions concerning the origin of the tornado rotation and the influence of the rotating barb on the rest of the filament . @xcite and @xcite proposed that the barb - tornadoes are driven by photospheric vortex flows of the kind observed by @xcite and @xcite : according to this view , the barb field lines are rooted in the vortices and the latter s rotating motion is transferred to the barb . the authors also proposed that the barb tornadoes inject chromospheric plasma and helicity into the upper filament throughout the rotating barb . however , such vortex flows have yet not been observed at all below barbs , let alone as a matter of course . another possibility for the origin of spiral motions is three - dimensional reconnection ( at or above the photosphere ) during cancellation of photospheric magnetic fragments , since such reconnection will naturally produce vortex motions ( e. g. , * ? ? ? * ) and could also fuel a prominence with mass . a third possibility arises from the fact that a prominence represents a concentration of magnetic helicity in twisted magnetic fields . thus , if part of a prominence dips down towards the photosphere , it is possible that such magnetic helicity and its associated twisting motions may be focused in the dip . in this letter we discuss how the massive cool plasma is supported against gravity in a helical magnetic structure . we find that the barb - tornadoes bear many similarities to astrophysical plasma jets in which magneto - centrifugal forces accelerate the plasma . by using recent current tornado data and typical barb parameters we conclude that it is actually possible for the magnetic force to support and accelerate the cool barb plasma against gravity provided the structure is highly twisted and/or significant poloidal flows are present . inspired by the observations , we consider in the following an axisymmetric model rotating around a vertical axis . we use cylindrical coordinates @xmath5 with @xmath6 coinciding with the rotation axis . the axisymmetry condition implies that all quantities are @xmath7-independent : @xmath8 . an important restriction on the axisymmetric magnetic field is that the field lines should become vertical as we approach the rotation axis ( @xmath9 ) . the observed structure appears to be stationary with no important changes of shape in the euv images and doppler pattern for several hours . the alfvn speed is around one thousand @xmath10 in the corona and of order one hundred @xmath10 in the cool prominence plasma . thus , the travel time of a magnetic perturbation is less than a minute along the vertical axis of the tornado . this indicates that , during the few hours the observation , the system has plenty of time to relax and produce a stationary magnetic structure . we therefore set @xmath11 in the equations . in this situation the mhd induction and momentum equations become , respectively , @xmath12 where @xmath13 , @xmath14 , @xmath15 , @xmath16 and @xmath17 are the plasma density , the velocity , magnetic field , gas pressure and gravity respectively . both the plasma velocity and magnetic field can be naturally decomposed into _ poloidal _ and _ toroidal _ components , @xmath18 with @xmath19 . only for illustration purposes we are showing in figure [ fig : cartoon ] the force - free solutions of @xcite . the poloidal planes @xmath20 correspond to @xmath21 surfaces . given the axisymmetry , we can easily define the angular velocity @xmath22 using @xmath23 . the advection ( or inertial ) term @xmath24 can be written as @xmath25 i.e. , advection in the poloidal plane plus two acceleration terms associated with the prescribed rotation profile @xmath22 , the first of which is clearly the centripetal force of a circular motion . .,scaledwidth=50.0% ] in a stationary regime there must be force balance including the inertial terms . for ease of notation , we use the symbol @xmath26 for the sum of pressure gradient , gravity and centrifugal force : @xmath27 the poloidal part of the equation of motion ( [ eq : mhd2 ] ) can then be split into into its components parallel and perpendicular to @xmath28 , @xmath29 \cdot { { \vec{e}_\perp^{}}}\nonumber\\ & \;+\ ; & \left ( \frac{b_p^2}{{{\mu_0^ { } } } } -\rho \ , v_p^2 \right ) \kappa_{pol } \ ; , \label{eq : transverse_equilibrium_withflows}\\\nonumber\end{aligned}\ ] ] where @xmath30 , @xmath31 are the unit vectors in the poloidal plane parallel and perpendicular to @xmath28 , respectively , and @xmath32 and @xmath33 are the curvature and arc - length along the poloidal field lines ( the latter is chosen such that @xmath30 points in the sense of growing @xmath33 illustrated as dashed lines in fig . [ fig : cartoon ] ) . for future reference , we also note that @xmath34 and @xmath35 are defined through @xmath36 and @xmath37 , respectively , i.e. , they can be positive or negative . equation ( [ eq : longitudinal_equilibrium_withflows ] ) represents the steady flow of plasma along field lines and provides clues concerning the support of the cool barb plasma ; equation ( [ eq : transverse_equilibrium_withflows ] ) represents the global transverse equilibrium of the magnetic structure . the remaining component of the equation of motion , the azimuthal component , is @xmath38 as an additional remark concerning figure [ fig : cartoon ] , note that in a barb - tornado structure the density along the poloidal field lines should be larger close to the axis than in the outer regions of the structure . the observation of @xcite , which shows a dense column in absorption tapering off with height , may well be compatible with a helically opening structure as shown in the figure . in a situation of pure rotation there is no plasma flow along the poloidal field ( @xmath39 ) , and the inertial term ( [ eq : inertial ] ) reduces to the centripetal component @xmath40 . in this case , from equation ( [ eq : motion_azimuthal ] ) , we see that the azimuthal component of the lorentz force is zero , i.e. , @xmath41 is constant along each poloidal field line . on the other hand , using the induction equation one can easily see that in this case @xmath42 is constant along each given field line , in agreement with ferraro s isorotation law @xcite . the magnitudes of @xmath41 and @xmath42 are then determined by the boundary conditions of the problem . given the constancy of @xmath41 , we see from the longitudinal equilibrium equation ( [ eq : longitudinal_equilibrium_withflows ] ) that the lorentz force has no longitudinal component , and so the equation reduces to @xmath43 the lorentz force is thus purely poloidal and perpendicular to @xmath28 . calling @xmath44 the angle between the poloidal field and the horizontal direction , equation ( [ eq : longitudinal_equilibrium ] ) may be written @xmath45 implying a balance of the non - magnetic forces . note , in particular , that the centrifugal term could help support the plasma against gravity if the field lines are sufficiently close to horizontal ( i.e. , @xmath46 sufficiently small ) . is the foregoing purely - rotating stationary equilibrium a realistic possibility for the observed apparent barb tornadoes ? the latest observations @xcite reveal a rotational velocity of @xmath47 at the edges of the structure with @xmath48 , so @xmath49 . @xcite found average values of barb widths of @xmath50 in agreement with @xcite . with these values we can compare the centrifugal acceleration to the gravitational acceleration , @xmath51 with the values found by @xcite this ratio is even smaller . the only way to have centrifugal support of the plasma is then for the field lines to be almost horizontal , which contradicts the tornado picture . can a pressure gradient help support the plasma in a non - horizontal field ? hot , coronal plasma , can be supported by a pressure gradient against gravity across coronal distances even in vertical field lines . however , for cool prominence plasma the pressure scale - height is too small to balance gravity in barbs as tall as those observed . even if the field lines close to the rotation axis were filled with hot coronal plasma , the magnetic structure would have to turn almost horizontal ( say , @xmath52 , as given in eq . [ eq : centrifugal_force_ratio ] ) in the region holding cool prominence plasma . we conclude that the centrifugal force associated with the rotation can not support the cool barb plasma against gravity in a helical field structure . another way to illustrate this conclusion is to estimate the rotational speed necessary to have purely centrifugal support , namely @xmath53 assuming a magnetic field inclination of @xmath54 , say , at the edges of the observed barb tornadoes , the rotation velocity would have to be @xmath55 if we use the data of @xcite and @xmath56 when using those of @xcite , much larger than the measured speeds . we consider now a more general scenario allowing for flows in the poloidal direction . now the simple situation of constant @xmath42 and @xmath41 along the field lines no longer applies . checking for instance the azimuthal equation of motion ( [ eq : motion_azimuthal ] ) , we see that a change of specific axial angular momentum of the plasma elements associated with the poloidal motion must be associated with a non - zero toroidal component of the lorentz force , @xmath57 . hence , in general @xmath58 can no longer be constant along field lines . in this situation , the lorentz force also has a non - zero projection along poloidal field lines ( eq . [ eq : longitudinal_equilibrium_withflows ] ) , @xmath59 , @xmath60 in spite of the added complication of this general scenario , there is a set of conserved quantities along the field lines . one can obtain them by following the general procedure used in the theory of astrophysical jets @xcite . the induction equation requires that @xmath61 , so the poloidal velocity must be parallel to the poloidal field lines , for otherwise a singularity would arise in the toroidal electric field at the @xmath6-axis . so , we can write @xmath62 integrating the mhd equations along field lines and simplifying the resulting expressions , a set of conserved quantities results , namely , @xmath63 where @xmath64 , @xmath65 , and @xmath66 are all constant along each poloidal field line . those relations allow us to find an explicit expression for @xmath41 along the poloidal field . one can write it in terms of the _ poloidal alfvn mach number _ @xmath67 and of the _ alfvn radius _ , @xmath68 , defined by @xmath69 as follows : @xmath70 expression ( [ eq : rbphik ] ) become singular when @xmath71 . in the classical wind solutions , the flow speed increases from sub - alfvenic to super - alfvenic at a given point , and , to avoid the singularity , this transition must happen precisely at the alfvn radius , @xmath72 . in such models , this requirement serves as an internal boundary condition to pick up the desired trans - alfvenic solution instead of the a completely sub - alfvenic or completely super - alfvenic solution . in our case , however , it is unlikely that the flows reach alfvnic values within the tornado ; rather , as shown below , we expect @xmath73 to remain below @xmath74 throughout . following eq . ( [ eq : longitudinal_equilibrium_withflows ] ) and the results of section [ sec : steady_rotation ] , to support the cool plasma along field lines the magnetic force @xmath59 of eq . ( [ eq : magforcegeneral ] ) should be larger than the centrifugal force , @xmath75 . from eqs . ( [ eq : cons1 ] ) and ( [ eq : cons3 ] ) , the ratio of these forces is @xmath76 in terms of the ratios ( @xmath77 and @xmath78 ) of azimuthal to poloidal components for the magnetic fields and plasma velocities : @xmath79 and the length @xmath80 , defined as @xmath81 the characteristic length ( @xmath82 ) can be assumed to be of order the radial size of the system , i.e. , @xmath83 . hence , from equation ( [ eq : comparison - mag - cent ] ) , it is necessary for the value of the parameter @xmath84 to be large in order to have a barb - tornado dominated by the magnetic force . we see that a high level of magnetic twist , and a comparatively large poloidal velocity ( compared to the rotational velocity ) are necessary to provide magnetic support . we can derive a more exact estimate of the possibilities of magnetic support of tornado plasma against gravity using expression ( [ eq : magforcegeneral ] ) for the longitudinal magnetic force combined with expression ( [ eq : rbphik ] ) . first of all , we can use the definitions of @xmath65 and @xmath64 to write their product in the form @xmath85 keeping in mind , nevertheless , that @xmath64 , @xmath65 ( and @xmath68 ) are constant along each field line . we can now derive eq . ( [ eq : rbphik ] ) with respect to the arc - length and , after a little algebra , obtain the general expression @xmath86 \,\ ] ] where we have used @xmath87 , and called @xmath88 the scale of variation of @xmath13 along poloidal field lines in terms of the cylindrical radius , as follows : @xmath89 for the estimate that follows , it is best to write equation ( [ eq : fmlong_estimate_1 ] ) in terms of an observed quantity , namely @xmath90 , and of the ratio @xmath91 , which turns out to be the essential dimensionless variable in the resulting expression . further , to calibrate the possibilities of magnetic support , we normalize ( [ eq : fmlong_estimate_1 ] ) with respect to gravity along the poloidal field , @xmath92 . the result is : @xmath93 \cot\theta\ , . \label{eq : support}\end{aligned}\ ] ] for the applications to prominence barbs we envisage cases with @xmath94 . the term @xmath95 in eq . [ eq : support ] therefore favors magnetic support . in fact , in many cases @xmath96 and so for simplicity this is the case we consider . assuming the value of the ratio @xmath97 to be given from observations expression ( [ eq : support ] ) is basically a quadratic polynomial in @xmath91 with parameters @xmath88 and @xmath44 . in figure [ fig : ratio ] , we show ( [ eq : support ] ) for @xmath98 ( upper panel ) and @xmath99 ( lower panel ) , for different relevant values of @xmath88 . to draw the figure we have used @xmath100 ( i.e. , @xmath101 km s@xmath102 and @xmath103 mm ) , which is the value that led us in sec . [ sec : steady_rotation ] , equation [ eq : centrifugal_force_ratio ] , to conclude that there is no possible support for the plasma in the purely rotating case . for magnetic support , the relevant stretches of the curves are those near the dashed horizontal line at ordinate @xmath104 . for ease , we have marked the cut of each curve with that horizontal line with a large black dot and a thin dotted vertical line . the following guidelines have been used in the choice of values for @xmath88 : in a solar tornado @xmath88 is probably negative , i.e. , the density decreases as one goes outward along the tornado field lines . also , @xmath105 should not be larger than of order unity , since the lengthscale of variation of @xmath13 should be not too different from @xmath106 itself . finally , in the figure we restrict ourselves to concave - upward parabolas ( i.e , @xmath107 ) , since those are the most favorable cases for magnetic support . we see that it is not difficult to find values of @xmath91 that yield magnetic support of the plasma against gravity . in all cases shown , though , the basic variable @xmath108 must be above @xmath74 : for @xmath109 , for instance , the values marked in the figure range from @xmath110 to @xmath111 , on the negative side and from @xmath112 to @xmath113 on the positive side . note that the actual ranges are @xmath114 $ ] and @xmath115 $ ] . for @xmath116 , the absolute values are smaller . we expect @xmath78 to be perhaps @xmath74 or @xmath117 , reflecting the fact that the outward motion of the tornado is possibly as fast as the rotating motion or a little less so . thus , for magnetic support one would need a substantial level of magnetic twist , possibly @xmath118 from a few to several units . if the poloidal flow becomes less important , then the amount of magnetic twist would increase to unrealistic values . must be reached ( marked by dots for the different curves),width=302 ] in this work we have investigated a possible mechanism to support dense plasma in a prominence barb against gravity . we have modeled a barb tornado as an axisymmetric structure with rotation about the symmetry axis , in which the magnetic field is vertical close to the tornado axis . pressure gradients are ruled out as a support for the plasma because the small pressure scale height of prominence plasma implies that they could support vertical structures only a few hundred kilometers tall , much smaller than the height of observed barbs . in a barb tornado with a rotating helical field , extra magneto - centrifugal forces are present . we have found that the centrifugal force is much smaller than solar gravity for the barb - tornadoes observed so far . however , the poloidal magnetic force is a good candidate to support cool prominence plasma or even to inject such plasma into a prominence . for that , the structure must have significant magnetic twist and/or poloidal flows not much smaller than the rotational velocities . whether this is or otherwise the case is a question for future observations . however , more theoretical work and observational evidence are needed to elucidate the origin of poloidal flows or magnetic twist . m. luna and f. moreno - insertis acknowledge the support by the spanish ministry of economy and competitiveness through projects aya2011 - 24808 and aya2014 - 55078-p . m. l. is also grateful to erc-2011-stg 277829-spia . e. r. priest is grateful to the uk stfc and the leverhulme trust for financial support . the authors also are grateful to d. orozco - surez and k. knizhnik for helpful discussions .

recent high - resolution and high - cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado - like structure . additional evidence has been provided by doppler measurements . the observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb . this motion is persistent for several hours and has been interpreted in terms of rotational motion of prominence feet . several authors suggest that such barb motions are rotating helical structures around a vertical axis similar to tornadoes on earth . one of the difficulties of such a proposal is how to support cool prominence plasma in almost - vertical structures against gravity . in this work we model analytically a tornado - like structure and try to determine possible mechanisms to support the prominence plasma . we have found that the lorentz force can indeed support the barb plasma provided the magnetic structure is sufficiently twisted and/or significant poloidal flows are present .

SECTION 1. SHORT TITLE. This Act may be cited as the ``National Initiative on Surface Transportation and the Environment Act''. SEC. 2. CONGESTION MITIGATION AND AIR QUALITY IMPROVEMENT PROGRAM. (a) Eligible Projects.--Section 149(b) of title 23, United States Code, is amended-- (1) by inserting after ``nonattainment area'' the first place it appears ``(including an area subsequently redesignated as an attainment area)''; and (2) by inserting ``or thereafter'' after ``1994''. (b) Priority for Projects With Long-Term Sustainable Air Quality Benefits.--Section 149 of such title is amended by adding at the end the following: ``(e) Priority for Projects With Long-Term Sustainable Air Quality Benefits.--The Secretary, after consultation with the Administrator, shall establish a system for ranking projects and programs that are likely to have long-term sustainable air quality benefits, including energy efficiency, and for providing priority funding under this section for projects and programs that are ranked the highest under such system.''. (c) Authorization of Appropriations.--For the purposes of carrying out the congestion mitigation and air quality improvement program under title 23, United States Code, there is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) $1,300,000,000 for each of fiscal years 1998, 1999, 2000, 2001, 2002, and 2003. (d) Sense of Congress.--In order to provide the increased authorization of appropriations under subsection (c), it is the sense of Congress that the authorization of appropriations from the Highway Trust Fund for the National Highway System and the surface transportation program shall be reduced in the aggregate by $400,000,000 for each of fiscal years 1998 through 2003. SEC. 3. ASSESSMENT AND CLEANUP OF BROWNFIELD SITES. (a) National Highway System.--Section 103(i) of title 23, United States Code, is amended by adding at the end the following: ``(14) In accordance with all applicable Federal law and regulations, participation in assessment and cleanup of brownfield sites relating to projects funded under this title, projects on the rights-of-way of facilities constructed on such system under this title before, on, or after the date of the enactment of this paragraph, and projects for development of a brownfield site if such development will provide a substantive and demonstrable benefit to transportation on such system, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility. Contributions toward these efforts may occur in advance of project construction only if such efforts are consistent with all applicable requirements of Federal law and regulations and State transportation planning processes.''. (b) Surface Transportation Program.-- (1) Eligible projects.--Section 133(b) of title 23, United States Code, is amended by adding at the end the following: ``(12) In accordance with all applicable Federal law and regulations, participation in assessment and cleanup of brownfield sites relating to projects funded under this title, projects on the rights-of-way of facilities constructed under this title before, on, or after the date of the enactment of this paragraph, and projects for development of a brownfield site if such development will provide a substantive and demonstrable benefit to motor vehicle transportation, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility. Contributions toward these efforts may occur in advance of project construction only if such efforts are consistent with all applicable requirements of Federal law and regulations and State transportation planning processes.''. (2) Funding for urbanized areas over 200,000 population.-- Section 133(d) of such title is amended-- (A) in paragraph (3)(A)-- (i) by striking ``62.5'' and inserting ``70''; and (ii) by striking ``37.5'' and inserting ``30''; and (B) in paragraph (3)(C) by striking ``62.5'' and inserting ``70''. (3) Definitions.--Section 133 of such title is further amended by adding at the end the following: ``(g) Definitions.--In this section and section 103(i), the following definitions apply: ``(1) Brownfield site.--The term `brownfield site' means a parcel of land that contains or contained abandoned or underused commercial, industrial, or public facility, the expansion or redevelopment of which may be complicated by the presence or potential presence of hazardous substances, pollutants, or contaminants. ``(2) Facility.--The term `facility' has the meaning such term has under section 101 of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (42 U.S.C. 9601). ``(3) Hazardous substance.--The term `hazardous substance' has the meaning such term has under such section 101. ``(4) Pollutant or contaminant.--The term `pollutant or contaminant' has the meaning such term has under such section 101.''. (c) Federal Transit Programs.-- (1) Block grants.--Section 5307(b) of title 49, United States Code, is amended by adding at the end the following: ``(6) Assessment and cleanup of brownfield sites.--Amounts under this section may also be made available for assessment and cleanup of brownfield sites relating to projects funded under this title, projects on the rights-of-way of facilities constructed under this title before, on, or after the date of the enactment of this paragraph, and projects for development of a brownfield site if such development will provide a substantive and demonstrable benefit to mass transportation, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility. Such assessments and cleanups shall be carried out in accordance with all applicable Federal law and regulations.''. (2) Discretionary grants and loans.--Section 5309(a) of such title 49 is amended-- (A) by striking ``and'' at the end of subparagraph (F); (B) by striking the period at the end of subparagraph (G) and inserting ``; and''; and (C) by adding at the end the following: ``(H) in accordance with all applicable Federal law and regulations, assessment and cleanup of brownfield sites relating to projects funded under this title, projects on the rights-of-way of facilities constructed under this title before, on, or after the date of the enactment of this subparagraph, and projects for development of a brownfield site if such development will provide a substantive and demonstrable benefit to mass transportation, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility.''. (3) Financial assistance for other than urbanized areas.-- Section 5311(b)(1) of such title 49 is amended by inserting before the period at the end of the first sentence the following: ``and, in accordance with all applicable Federal law and regulations, assessment and cleanup of brownfield sites relating to projects funded under this section, projects on the rights-of-way of facilities constructed under this section before, on, or after the date of the enactment of the National Initiative on Surface Transportation and the Environment Act, and projects for development of a brownfield site if such development will provide a substantive and demonstrable benefit to mass transportation, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility in such areas''. (4) Definitions.--Section 5302(a) of such title 49 is amended-- (A) by redesignating paragraphs (1) through (13) as paragraphs (2) through (14), respectively; and (B) by inserting before paragraph (2), as so redesignated, the following: ``(1) Brownfield site.--The term `brownfield site' means a parcel of land that contains or contained abandoned or underused commercial, industrial, or public facility, the expansion or redevelopment of which may be complicated by the presence or potential presence of hazardous substances, pollutants, or contaminants. In this paragraph, the terms `facility', `hazardous substance', and `pollutant or contaminant' have the meaning such terms have under section 101 of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (42 U.S.C. 9601).''. SEC. 4. WETLANDS RESTORATION PROGRAM. (a) Establishment.--Chapter 1 of title 23, United States Code, is amended by adding at the end the following: ``Sec. 162. Wetlands restoration program ``(a) Establishment.--The Secretary shall establish a wetlands restoration program under which the Secretary may make grants to States for projects to mitigate against losses of wetlands that have occurred as a result of Federal-aid highway construction projects carried out before the date of the enactment of this section. ``(b) Allocation of Funds.--The Secretary shall allocate funds made available to carry out this section for a fiscal year among the States in the ratio that the number of acres of wetlands lost by each State as a result of Federal-aid highway construction projects in the preceding fiscal year bears to the number of acres of wetlands lost by all States as a result of such projects in such fiscal year; except that no State may receive more than 5 percent of such funds. ``(c) Authorization of Appropriations.--There is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) $16,666,000 per fiscal year for each of fiscal years 1998 through 2003 to carry out this section. Such sums shall remain available until expended.''. (b) Conforming Amendment.--The table of sections for such chapter is amended by adding at the end the following: ``162. Wetlands restoration program.''. SEC. 5. NONPOINT SOURCE POLLUTION. (a) Use of STP Funds for Mitigation of Water Pollution.--Section 133(d) of title 23, United States Code, is amended by adding at the end the following: ``(3) For mitigation of water pollution.--1 percent of the funds apportioned to a State under section 104(b)(3) for a fiscal year shall only be available for monitoring, mitigating, and cleaning up water pollution due to highway runoff.''. (b) Applied Research and Technology Program.--Section 307(e) of such title is amended-- (1) by redesignating paragraphs (9) through (13) as paragraphs (10) through (14), respectively; and (2) by inserting after paragraph (8) the following: ``(9) Porous paving materials.--As part of the program under this subsection, the Secretary shall carry out a program to assess the benefits of using porous paving materials for highways and parking lots as a method of mitigating water pollution due to highway runoff.''. SEC. 6. INCENTIVES FOR REDUCTIONS IN MOTOR VEHICLE EMISSIONS. (a) In General.--Chapter 1 of title 23, United States Code, is further amended by adding at the end the following: ``Sec. 163. Incentives for reductions in motor vehicle emissions ``(a) Grants to MPO's.-- ``(1) Authority to make grants.--The Secretary may make grants to up to 10 metropolitan planning organizations designated under section 134 for implementing alternative transportation strategies to achieve reductions in motor vehicle emissions. Such strategies include coordinating land uses with transportation systems, creating balanced commercial and residential regions, promoting alternative fuel vehicles and alternative transport strategies, designing local modeling systems, and increasing full public participation. ``(2) Amount of grants.--Each grant made to a metropolitan planning organization under this subsection in a fiscal year shall be in an amount equal to one-tenth of the amount made available to carry out this subsection in such fiscal year. ``(3) Authorization of appropriations.--There is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) to carry out this subsection $4,500,000 per fiscal year for each of fiscal years 1998 through 2003. Such sums shall remain available until expended. ``(b) Grants to States.-- ``(1) Authority to make grants.--On or before December 31, 2003, the Secretary shall award a grant to each of the 10 States that the Secretary determines have achieved during the period beginning on October 1, 1997, and ending on September 30, 2003, the greatest per capita reduction in fuel consumption. ``(2) Use of grants.--A State may obligate amounts from grants received under paragraph (1) for projects eligible for funding under section 149. ``(3) Amount of grants.--Each grant made under this subsection shall be in an amount equal to one-tenth of the total amount made available to carry out this subsection. ``(4) Authorization of appropriations.--There is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) for fiscal years 1997 through 2003 $500,000,000 in the aggregate to carry out this subsection. Such sums shall remain available until expended.''. (b) Conforming Amendment.--The table of sections for such chapter is amended by adding at the end the following: ``163. Incentives for reductions in motor vehicle emissions.''.

National Initiative on Surface Transportation and the Environment Act - Amends Federal highway provisions to expand eligibility for projects under the congestion mitigation and air quality improvement program. Directs the Secretary of Transportation to establish a system for ranking projects and programs that are likely to have long-term sustainable air quality benefits and for providing funding for projects and programs that are ranked the highest under such system. Authorizes appropriations. Expresses the sense of the Congress that the authorization of appropriations from the Highway Trust Fund for the National Highway System and the surface transportation program (STP) shall be reduced in the aggregate by $400 million for each of FY 1998 through 2003. (Sec. 3) Requires that participation in assessment and cleanup of brownfield sites relating to specified projects provide a substantive and demonstrable benefit to transportation on such system, including reduction of congestion, increased use of mass transit, and improved access to a transportation facility. Permits contributions toward such efforts to occur in advance of project construction only if such efforts are consistent with Federal requirements and State transportation planning processes. Increases the percentage of funds apportioned to a State for the STP that must be obligated to urbanized areas with population of over 200,000 and other areas of the State in proportion to their relative share of the State's population. Makes Federal transit block grants, discretionary grants and loans, and financial assistance for other than urban areas available for assessment and cleanup of brownfield sites relating to specified projects if such development will provide a substantive and demonstrable benefit to mass transportation. (Sec. 4) Directs the Secretary to establish a wetlands restoration program under which the Secretary may make grants to States for projects to mitigate losses of wetlands that have occurred as a result of Federal-aid highway construction projects. Authorizes appropriations. (Sec. 5) Makes one percent of STP funds apportioned to a State for a fiscal year available for monitoring, mitigating, and cleaning up water pollution due to highway runoff. Directs the Secretary to carry out a program to assess the benefits of using porous paving materials for highways and parking lots as a method of mitigating such pollution. (Sec. 6) Authorizes the Secretary to make grants to up to ten metropolitan planning organizations designated for implementing alternative transportation strategies to achieve reductions in motor vehicle emissions. Authorizes appropriations. Directs the Secretary, on or before December 31, 2003, to award a grant to each of the ten States that the Secretary determines have achieved the greatest per capita reduction in fuel consumption between October 1, 1997, and September 30, 2003. Authorizes appropriations.

interaction of a single mode of electromagnetic field with a two - level atom is the simplest problem in matter - radiation coupling . a model for the interaction , introduced by jaynes and cummings @xcite , treats the atom as a dipole placed in an external field . the jaynes - cummings ( jc ) model has provided a lot of impetus for theoretical explorations and experimental verifications @xcite . the hamiltonian for the model is @xmath0 here @xmath1 , the hamiltonian for the atom and field in the absence of interaction , is @xmath2 . the atomic transition frequency is @xmath3 , the field frequency is @xmath4 and @xmath5 is the coupling constant . we denote the creation operator by @xmath6 , annihilation operator by @xmath7 , and their action on the basis states of the harmonic oscillator are + @xmath8 the atom has two - levels , @xmath9 and @xmath10 , the ground and excited states . the operators @xmath11 , @xmath12 and @xmath13 act on the states as given below : @xmath14 atomic inversion , defined as the difference in probabilities for the atom to be in the excited and ground states , as predicted by jc model is a sum of quasiperiodic functions with incommensurate frequencies . the model predicts collapses , revivals and ringing revivals in the time - development of atomic inversion@xcite the revival phenomenon is entirely quantal , and hence the model is very important for testing predictions of quantum theory . the model has been generalized in very many ways . we list the respective hamiltonian for some of the models : + 1 ) buck - sukumar model@xcite @xmath15 with this particular form of intensity - dependent coupling the atomic - inversion is a sum of periodic functions . this model is very interesting as it can be written as a combination of generators of su(1,1 ) algebra@xcite . generalization to two - photon case , where two - photons are absorbed or emitted in atom - field interactions , has been done . once again the su(1,1 ) algebraic structure in the model is used to solve the problem @xcite . + + 2 ) kerr - nonlinearity@xcite + @xmath16 this is an effective hamiltonian for a system in which the electromagnetic field mode is excited in a kerr medium . the medium is modelled as an anharmonic oscillator@xcite . + + 3)dicke - tavis - cummings model@xcite + + in this model , the interaction between field and a group of two - level atoms is considered and the hamiltonian is @xmath17 4 ) nonlinear jaynes - cummings model + + by including the motion of atom in the external field , the coupling is made position dependent . this offers enormous possibilities to tailor the form of atom - field interaction @xcite . the general form for the hamiltonian is @xmath18 here @xmath19 is an operator - valued function of the number operator @xmath20 and @xmath21 is an integer . the objective of the present paper is to study the dynamics of a two - level atom interacting with a single mode of electromagnetic field . the interaction is governed by the hamiltonian @xmath22 + \chi\cot\aot + g\omega ( { \sqrt{1+k\co\ao } } \ao \sigma_+ + \co { \sqrt{1+k\co\ao } } \sigma_-).\ ] ] this hamiltonian is an example for nonlinear jc model including kerr term . note that we have scaled the coupling constant @xmath5 by @xmath4 . the parameter @xmath23 is @xmath24 and the coupling constant for the kerr term is @xmath25 . this will simplify the expressions we derive in sequel . in particular , we set @xmath26 which amounts to studying a new hamiltonian @xmath27 . the speciality of the hamiltonian @xmath28 is that it becomes @xmath29 when the parameter @xmath30 is set equal to zero . further , the usual holstein - primikoff realization is obtained when @xmath31 so that the interaction is approximately given by @xmath32 , which is same as the interaction studied in ref.@xcite . yet another form of interaction occurs when @xmath33 . if the photon number distribution is such that @xmath34 for all @xmath35 under the peak of the distribution , then eq . [ hamil ] leads to @xmath36\right].\ ] ] further , when @xmath33 so that we can neglect @xmath37 in comparison to unity but retain @xmath38 , we arrive at @xmath29 with an additional kerr term . this system has been studied in ref.@xcite . many well studied systems are thus special cases of the hamiltonian considered for discussion in the present paper . the organization of the paper is as follows . in section ii we study the algebraic aspects of the hamiltonian and construct the eigenvectors and eigenvalues . section iii is devoted to study the atomic inversion and approximate expressions are obtained for first collapse and revival periods when the field is in a coherent state . the time - development of field statistics is discussed in section iv and the results are summarized in section v. in this section we study the algebraic aspects of the generalized hamiltonian given in eq . ( [ hamil ] ) . we introduce a set of operators which are closed under commutation . this algebraic structure is exploited to determine the time - evolution operator to evolve the initial state of the atom - field system . the eigenvalues and the corresponding eigenvectors are constructed . the hamiltonian given in eq.[hamil ] is written as @xmath39 wherein we have set @xmath40 and @xmath41 . further , we assume that @xmath30 is nonnegative and restricted to take values less than or equal to unity . formally , the hamiltonian @xmath28 has the same structure as @xmath29 with @xmath7 and @xmath6 replaced by @xmath42 and @xmath43 . however , the former corresponds to kerr - type medium with intensity - dependent coupling for atom - field interaction . the difference is very clear in the commutation relations among the operators . from the realisation of @xmath42 and @xmath43 in terms of @xmath6 and @xmath7 , we arrive at @xmath44 & = & 2 k_0,\cr [ k_0 , k_{\pm } ] & = & \pm k k_\pm .\end{aligned}\ ] ] the operator @xmath45 is @xmath46 . thus , the operators @xmath47 and @xmath45 form a closed algebra . it worth noting that the commutation relations define the su(1,1 ) algebra when @xmath48 . on the other hand , to get the well - known heisenberg - weyl algebra generated by @xmath49 and the identity @xmath50 we set @xmath51 . two different algebras are realized depending on the value of @xmath30 and hence the algebra of @xmath47 and @xmath45 is said to be an interpolating algebra " . an invariant operator , which commutes with @xmath52 and @xmath45 , for the algebra is given by @xmath53 . the coherent states corresponding to this algebra and their hilbert space properties are known @xcite . the atom - field evolution is studied in the space of @xmath54 and @xmath55 , where @xmath56 . the state @xmath54 means that the atom is in the excited state @xmath10 and the field in the @xmath57 excited state @xmath58 . the states @xmath54 and @xmath55 are eigenstates of @xmath59 and the respective eigenvalues are @xmath60 and @xmath61 . the hamiltonian @xmath28 admits a constant of motion n such that the commutator @xmath62 $ ] vanishes . explicitly , @xmath63 . note that when @xmath51 , @xmath64 becomes @xmath65 , the constant of motion for @xmath29 . the interaction part of @xmath28 is such that the state @xmath54 is taken to @xmath66 and _ vice versa _ , during the evolution of the atom - field system . thus , the entire hilbert space is split into subspaces spanned by @xmath54 and @xmath66 and the dynamics confined to individual subspaces . in one such subspace , specified by the value of @xmath35 , the hamiltonian matrix is @xmath67 the detuning parameter @xmath68 is @xmath69 . the eigenvalues of the hamiltonian are @xmath70 and the corresponding eigenvectors are @xmath71 the expansion coefficients are @xmath72 in which we have set @xmath73 and @xmath74 . the energy difference between the levels @xmath75 and @xmath76 is @xmath77 . the minimum of the separation occurs when @xmath68 equals @xmath78 and the corresponding difference is @xmath79 . in fig . 1 we have plotted the energy eigenvalues @xmath80 and @xmath81 as a function of @xmath68 . the dashed lines represent the eigenvalues when @xmath82 , _ i.e. _ , @xmath83 . in this case the eigenvalues cross each other as @xmath68 increases from negative to positive values . the continuous lines represent the energy eigenvalues for @xmath84 . the diverging eigenvalue separation beyond the minimum separation indicates `` level repulsion '' in the eigenvalues of the dressed atom . the effect of nonzero @xmath30 is to shift the value of @xmath68 at which the minimum separation or the crossing occurs . if @xmath51 , the minimum as well as the crossing occur at @xmath85 . to understand the dynamics of the atom - field system , we solve for the state of the system in interaction picture , where the evolution equation is @xmath86 here @xmath87 is the transformed interaction given by @xmath88 ( \sigma_- k_++\sigma_+ k_- ) \exp[-it(\omega k_+k_- + { \nu\over 2}\sigma_z)].\ ] ] the effect of the transformation on the interaction term is obtained from the following results : @xmath89 and their adjoints . note that the ordering of operators should be maintained in the rhs of the first of the results . using these relations , the interaction picture hamiltonian is written as @xmath90+\hbox{adjoint}.\ ] ] at any time @xmath91 , let the state of the atom - field system be represented as @xmath92 the coefficients @xmath93 and @xmath94 , determined in terms of their initial values by the evolution equation eq.[iph ] , are @xmath95 c_{e , n}(0)-\nonumber\\ & & { 2ig\sqrt{(n+1)(1+kn)}\over\omega_n } \sin\left({\omega_n t\over 2}\right)c_{g , n+1}(0),\\ \exp\left({i\delta_n t\over 2}\right ) c_{g , n+1}(t)&= & \left [ \cos({\omega_n t\over 2})+{i\delta_n\over\omega_n } \sin\left({\omega_n t\over 2}\right)\right ] c_{g , n+1}(0)\nonumber\\ & & - { 2ig\sqrt{(n+1)(1+kn)}\over\omega_n } \sin\left({\omega_n t\over 2}\right)c_{e , n}(0).\end{aligned}\ ] ] the rabi frequency @xmath96 is @xmath97 . the dependence of @xmath96 on @xmath35 such is that there is a minimum value for the rabi frequency when @xmath35 satisfies @xmath98 , provided @xmath99 . the variation of @xmath96 with respect to @xmath35 is shown in fig . 2 . in the case of @xmath29 , the rabi frequency varies linearly with @xmath35 and hence there is no minimum . the existence of a minimum rabi frequency has important consequences for the dynamics of atomic - inversion , squeezing , photon - statistics , _ etc . _ and they are discussed in the following sections . + let the rabi frequency attain its minimum for some specific value of @xmath35 , denoted by @xmath100 . therefore , we have @xmath101 the @xmath35 dependence of rabi frequency , for values of @xmath35 close to @xmath100 , is obtained by taylor expanding @xmath96 around @xmath100 , upto second order . the resultant expression is @xmath102 in fig . 2 the values predicted by the approximate expression for @xmath96 are compared with those of the exact expression . it is clear that for the chosen values of @xmath5 , @xmath30 and @xmath100 , the values match very well for those values of @xmath35 under the peak of the photon number distribution . quantitatively , the fractional difference is less than 3% . in the previous section we constructed the complete state of the atom - field system in the dressed atom basis in interaction picture . the state @xmath103 in the schrdinger picture is easily obtained by premultiplying the interaction picture state function @xmath104 by @xmath105 . in this section , we study the temporal evolution of atomic inversion . + the time - dependent state vector @xmath104 of the system is determined completely once the coefficients @xmath93 and @xmath94 are known , which , in turn , are specified by their initial values . for instance , if the atom is initially in the excited state , we have @xmath106 and @xmath107 . the probability that the atom is in the excited state , irrespective of the state of the field , is @xmath108 and to be in the ground state is @xmath109 . the photon number distribution of the field is @xmath110 . the difference of these two probabilities is atomic inversion . for the specified initial condition , namely , the atom is initially in the excited state , the atomic inversion @xmath111 is @xmath112,\ ] ] and time - dependent part of @xmath111 is @xmath113 the quantity @xmath114 exhibits rich structure in its evolution . it exhibits collapse and revivals when the initial photon distribution is taken to be a poissonian distribution of mean photon number @xmath100 , which corresponds to the field being in a coherent state @xmath115 . the photon number distribution for the state is @xmath116 . this distribution has a single peak and the standard deviation is @xmath100 . hence , the major contribution to the sum in eq.[wtime ] comes from a few terms with @xmath35 around the peak . with this choice of @xmath110 , we have plotted in fig . 3a the evolution of @xmath114 as a function of time . the time required for the first collapse and the following revival , denoted by @xmath117 and @xmath118 respectively , can be estimated approximately . for the revival to occur , the terms corresponding to those @xmath35 around the peak , should be in phase . thus , we require @xmath119 be equal to @xmath120 . the difference of the nearest - neighbour rabi frequencies is @xmath121 the constants @xmath122 and @xmath123 are @xmath124 and @xmath125 respectively . the revival time @xmath118 is @xmath126 . + for the inversion to collapse , the terms in the sum on the rhs of eq.[wtime ] should be uncorrelated . since the width of a possionian distribution is where the probability @xmath110 is appreciable , the condition for collapse is written as @xmath127 . if @xmath100 is large , the expression for @xmath117 is @xmath128 . the function @xmath114 exhibits rich features when detuning is close to @xmath129 . in fig . we have shown the behaviour of @xmath114 for three different values of @xmath68 . the values for the parameters are @xmath84 , @xmath130 , @xmath26 , @xmath131 and the corresponding @xmath129 is 0.01606 . the values are so chosen that the rabi frequency attains its minimum when @xmath35 is near @xmath132 , the average photon number . the evolution of @xmath114 with @xmath133 is shown as the top most figure , marked @xmath134 in fig . the figure @xmath135 corresponds to @xmath136 and the one marked @xmath137 is for @xmath138 . the envelope of @xmath114 when detuning equals @xmath129 , is distinct with structures repeating without much distortion . this should be compared with the top and bottom figures , which correspond to @xmath139 , which exhibit random oscillations and do not have neat envelope . as noted in section ii , su(1,1 ) algebra is realized in terms of @xmath52 and @xmath45 when @xmath48 . if we consider resonant interaction @xmath140 , then @xmath114 can be estimated approximately for the su(1,1 ) case . the field is taken to be in a coherent state @xmath141 such that @xmath142 . we use @xmath143 and @xmath144 to arrive at @xmath145 . with these approximations , we arrive at @xmath146 in which we have used @xmath147 . the magnitude of @xmath114 is negligible in this case and so there is no perceptible collapse or revival . this is due to the presence of kerr term and the fact that it dominates over @xmath20 in the hamiltonian . however , we point out that collapses and revivals are present in @xmath114 if @xmath148 . in the previous section , we studied the dynamics of the two - level atom , in particular , the atomic inversion . in the present section , we explore the temporal behaviour of field statistics and field amplitudes . as in the previous section , the field is initially in a coherent state of complex amplitude @xmath149 and the atom is taken to be in its excited state . with these initial conditions , the probability distribution of photons at time @xmath91 is @xmath150\end{aligned}\ ] ] coherent states are the wavepackets whose behaviour is closest to that of a classical particle and hence are called classical states . nevertheless , during their evolution in time the states may not be classical . the photon statistics of coherent states is poissonian . any deviation from this behaviour is characterized by mandel s q parameter defined as @xmath151 . using the time - dependent probability distribution @xmath152 , the expectation values in the expression for q parameter are @xmath153 ^ 2\over \sum_{n=0}^\infty p(n , t ) n}\ ] ] for coherent states , q is unity . any value of q less than unity is nonclassical . in fig . 4 the time evolution of q parameter for an initially coherent state and @xmath154 is given . the emergence of nonclassical behaviour ( @xmath155 ) is seen . though not shown in figure , we point out that for @xmath156 , the statistics does not become sub - poissonian . when @xmath48 and @xmath85 , the time - dependent part of @xmath152 is of negligible magnitude and so @xmath157 does not evolve in time . we define the field amplitudes to be @xmath158 these amplitudes satisfy the commutation relation @xmath159=i$ ] and hence they satisfy @xmath160 . the symbol @xmath161 stands for the expression @xmath162 , the variance in @xmath163 for a given field state . for coherent states of any amplitude @xmath149 , variances in @xmath163 and @xmath164 are the same and equal to 1/2 . a state is nonclassical if @xmath161 is less than 1/2 , the coherent state value . using the time - dependent state function given in eq . ( [ tdsf ] ) , the variances in the field amplitudes are given by @xmath165,\ ] ] and @xmath166.\ ] ] the expectation values of various operators in these expressions are @xmath167,\\ \langle\aot\rangle&=&\sum_{n=0}^\infty\sqrt{(n+1)(1+kn ) } \left [ c^*_{e , n}c_{e , n+2}+c^*_{g , n}c_{g , n+2}\right],\\ % end{eqnarray } \hbox{and}\nonumber\\ % \begin{equation } \langle\co\ao\rangle & = & \sum_{n=0}^\infty n \left [ c^*_{e , n}c_{e , n}+c^*_{g , n}c_{g , n}\right ] . % \end{equation}\end{aligned}\ ] ] the expectation values @xmath168 and @xmath169 are the complex conjugates of @xmath170 and @xmath171 respectively . the evolution of @xmath172 is shown in fig . as the field evolves in time , the variance in @xmath163 falls below 0.5 indicating that the quadrature exhibits squeezing . as a consequence of uncertainty relation , the @xmath164 quadrature does not show squeezing . however , when we set @xmath173 , the situation is reversed . in this case , squeezing is possible in @xmath164 and not in @xmath163 . an interesting feature is that the uncertainty in @xmath164 with @xmath174 is same as in @xmath163 when @xmath175 . the reason for this is that the field states are of the form @xmath176 wherein the coefficients @xmath177 are real for all @xmath35 . for such superpositions , the uncertainty in @xmath163 for a given @xmath149 is same as that in @xmath164 with @xmath149 replaced by @xmath178@xcite . a quantity of interest is the overlap of the state of the atom - field at time @xmath91 and that at @xmath179 . with the same initial conditions for the atom - field state as in the previous section , the overlap is @xmath180 \right\vert^2.\ ] ] the numerical value of the overlap lies between zero and unity . it is seen from fig . 6 that the overlap becomes zero at longer times . in other words , the time - evolved state is almost orthogonal to initial state . for short durations , an approximate expression for the decay of overlap is derived by replacing expression @xmath181 with the gaussian distribution @xmath182 and the sum over @xmath35 by integration . further , we set @xmath183 , with the assumption that @xmath64 is close to but not less than @xmath100 . here , prime denotes taking derivative with respect to @xmath35 and the suffix represents the value of @xmath35 where the derivative is evaluated . with these approximations we get , after neglecting oscillatory terms , @xmath184 ^{-{1\over 4}}\nonumber\\ & & \times \exp\left [ - n^2{\partial\omega_n\over\partial n}\vert_{n = n}{t^2\over 4 } \right]\end{aligned}\ ] ] similar expression can be derived for summation with @xmath185 . the above expression indeed predicts that the overlap function decays with time . when @xmath186 , the first derivative of @xmath96 vanishes and the exponential term in the envelope is absent . consequently the decay is slower . however , if the photon number distribution of the field is very broad , it is incorrect to truncate the taylor series and the expression in eq . ( [ appolap ] ) is invalid . the hamiltonian that contains the usual and intensity - dependent ( including kerr term ) jc models as limiting cases has been constructed . the nondissipative dynamics dictated by the generalized hamiltonian @xmath28 is completely solvable . the eigenvalues of the hamiltonian , with kerr term and intensity - dependent coupling , exhibits level - repulsion . in the case of nonvanishing kerr term , the rabi frequency , considered as a function of the photon number @xmath35 , attains a minimum . the dynamical behaviour of atomic - inversion , when detuning is so chosen to have the minimum rabi frequency , exhibits superstructures , which is absent in the usual jc model . the overlap of the initial coherent state and the time - evolved state decays with time . in the language of inner product , the initial coherent state is almost orthogonal to the time - evolved state . the results , except the occurrence of superstructures in atomic inversion , a consequence of nonvanishing kerr term , go over to those of the jc model , in the limit of @xmath187 . + we note that the formal equivalence between @xmath29 and @xmath28 is obtained by identifying @xmath43 with @xmath6 and @xmath42 with @xmath7 . this , in conjunction with the fact both the sets of operators @xmath188 and @xmath189 are closed under commutation , implies that the expansion coefficients @xmath190 for the evolution governed by @xmath28 are obtained from the corresponding expressions for the usual jc model by replacing @xmath68 by @xmath191 and @xmath5 by @xmath192 . hence , all those physical quantities , like the atomic inversion , quadrature fluctuations , _ etc . _ , computed in terms of the expansion coefficients are derivable from those of the jc model . fig . 1 dependence of eigenvalues @xmath80 and @xmath81 on detuning @xmath68 . the continuous curve corresponds to @xmath193 and the dashed curve corresponds to @xmath82 . here @xmath194 and @xmath131 . the dashed curves with positive and negative slopes correspond respectively to @xmath195 and @xmath196 . lower part of the figure is for @xmath197 and upper part for @xmath198 . + + fig . 2 variation of @xmath96 with @xmath35 . we have set @xmath199 , @xmath130 , @xmath131 and @xmath200 . the approximate and actual rabi frequencies are compared in the upper figure . dotted line corresponds to the approximate expression in eq.[appomega ] and continuous curve corresponds to exact expression . values of @xmath30 , @xmath5 , @xmath100 and @xmath68 are @xmath201 , @xmath202 , @xmath203 and @xmath204 respectively . the bottom curve shows the photon number distribution for the coherent state @xmath205 . + + fig . 3 time - dependent part of atomic inversion . case ( a ) corresponds to @xmath206 . case ( b ) is for @xmath156 and case ( c ) refers to @xmath207 . here case ( b ) shows @xmath208 and case ( c ) shows @xmath209 . . 4 time variation of @xmath210 , as the atom - field system evolves . the evolution is shown for three values of detuning , 0.01 ( continuous ) , 0.016061 ( dotted ) and 0.02 ( dashed ) . instants of @xmath210 less than 0.5 correspond to squeezing in @xmath163 quadrature . 5 mandel s @xmath157 parameter as a function of time . instants of @xmath155 correspond to sub - poissonian statistics . values of @xmath5 , @xmath30 and @xmath100 are same as in fig . 2 and @xmath211 . + + fig . 6 overlap of initial and time - evolved field states . y - axis corresponds to @xmath212 . the envelope of the overlap function decays with time implying that the initial state is almost orthogonal to the evolved state . the values of the parameters are same as in fig . 2 and the detuning @xmath68 is equal to @xmath204 .

interaction of a two - level atom with a single mode of electromagnetic field including kerr nonlinearity for the field and intensity - dependent atom - field coupling is discussed . the hamiltonian for the atom - field system is written in terms of the elements of a closed algebra , which has su(1,1 ) and heisenberg - weyl algebras as limiting cases . eigenstates and eigenvalues of the hamiltonian are constructed . with the field being in a coherent state initially , the dynamical behaviour of atomic - inversion , field - statistics and uncertainties in the field quadratures are studied . the appearance of nonclassical features during the evolution of the field is shown . further , we explore the overlap of initial and time - evolved field states . [ 12pt ] pacs nos:42.50 md , 42.50.dv , 05.30.-d + + + * short title * +

Photo by Filippo Monteforte/AFP/Getty Images Conventional wisdom, and many years of social science, have long said that the longer people wait to get married, the less likely they are to get divorced. There are obvious reasons why. With age, people mature, finish school, and settle into careers, which gives them the emotional and financial wherewithal to manage lifelong romantic commitments. The more we settle into ourselves, the theory goes, the better we are at settling down with others. A new analysis by Nicholas Wolfinger, a sociologist at the University of Utah, challenges that idea a bit. Using data from the National Survey of Family Growth, he finds that today, divorce risk declines for people who wait until their late 20s and early 30s to get married. But it rises again for those who delay walking down the aisle until their late 30s. Advertisement Again, this seems to be a new phenomenon. Wolfinger finds that during the mid-1990s, the odds of getting divorced continued declining the longer individuals held off on their first marriage. (For our purposes, just pay attention to the blue trend line. The gray shaded areas represent what are known as confidence intervals.) But now, the trend is u-shaped. “My data analysis shows that prior to age 32 or so, each additional year of age at marriage reduces the odds of divorce by 11 percent,” he writes. “However, after that the odds of divorce increase by 5 percent per year.” Call it the Goldilocks theory of marriage: Getting married too early is risky, but so is getting married too late. Your late 20s and early 30s are just right. Get Slate in your inbox. How come? Wolfinger isn't sure. But controlling the data for demographic and personal characteristics such as race, education, religion, sexual history, family background, or the size of the cities survey takers lived in didn't change the results, suggesting none of those factors could explain it. Ultimately, the professor suspects that there's a lot of self-selection at play: The sorts of people who wait a very long time to say "I do" just might not really be the marrying types, whether they realize it or not. Or, even if they are, their dating pool might have been whittled down to people who aren't. ||||| New report » Risk of split goes up 5 percent a year after age 32. High school sweethearts, take note. To avoid divorce, it's best to wait a few years before getting hitched. But holding out for too long isn't a good idea either, according to a new report from University of Utah researcher Nick Wolfinger. Research has long shown that couples who tie the knot in their late 20s have a lower rate of divorce than people who marry in their early 20s. But Wolfinger found that after the early 30s, odds of a legal split go up again — by 5 percent per year. Age 32 appears to be the tipping point, according to the analysis posted on the Institute for Family Studies' blog this week. The finding wasn't robust enough to warrant an academic article, the researcher said Friday. But he believes the trend is worth pointing out. ||||| The conventional wisdom is that waiting until you're older to get married will reduce your chances of divorce. But one new analysis suggests there may be a sweet spot to marrying — between the ages of 25 and 34. Nicholas Wolfinger, a professor of family and consumer studies and sociology at the University of Utah, looked at data from the National Survey of Family Growth (NSFG) for an analysis at the Institute for Family Studies. He found that although it used to be true that waiting until you're older was best, it may no longer be the case. As Wolfinger notes, there are several reasons why marrying younger can significantly increase your chances of divorce. For one, teenage years are more transformative, so people are likely to go through bigger fits of change that can separate them. But it's also the case that marrying younger correlates with lower educational attainment, which heightens the risk of divorce across the board. As for why marrying past 35 would increase someone's chances of divorce, Wolfinger poses a possible explanation: Does the experience of staying unmarried well past the age of 30 somehow make people unfit for a lasting marriage? It's possible to envision a scenario where this might be the case, particularly in the form of a complicated relationship history. If you've had many boyfriends or girlfriends, your exes might play havoc with your marriage. They may offer the temptation of adultery. If you've had children with one or more of your exes, there could be "baby mama drama." Indeed, having multiple sexual partners prior to marriage significantly increases the chances of getting divorced. Be that as it may, the number of prior sexual partners NSFG respondents had does not explain the relationship between age at marriage and marital stability. This result suggests that the mere experience of waiting past your early thirties to get married — a so-called "direct effect" — cannot explain why thirty-something marriages now have higher divorce rates than do unions formed in the late twenties. Instead, my money is on a selection effect: the kinds of people who wait till their thirties to get married may be the kinds of people who aren’t predisposed toward doing well in their marriages. For instance, some people seem to be congenitally cantankerous. Such people naturally have trouble with interpersonal relationships. Consequently they delay marriage, often because they can’t find anyone willing to marry them. When they do tie the knot, their marriages are automatically at high risk for divorce. More generally, perhaps people who marry later face a pool of potential spouses that has been winnowed down to exclude the individuals most predisposed to succeed at matrimony. For example, Wolfinger points out that surveys show people are now delaying their marriages until they can afford it — to around the ages of 27 to 29. Since these people seem to be approaching marriage rather responsibly, they could be the ones who are most likely to succeed, explaining the sweet spot around their age. But Philip Cohen, a professor of sociology at the University of Maryland, disputed Wolfinger's findings. Using a separate set of data from the 2011-2013 American Community Surveys, Cohen found that getting married later in life will still reduce the chance of divorce: It's hard to say which analysis is right, given that they're using different sets of data from different time periods. But it seems like an issue that will get more debate and study as time goes on — especially if a long-accepted trend is really changing. Of course, this all comes with the caveat that all of this data measures general trends, not individuals' experiences. So don't freak out if you married at 21, like I did, or after 35. Every marriage is different. These charts give us more of a look at the general people who tend to marry at certain ages, rather than whether individual marriages are doomed. Watch: The spread of marriage equality ||||| #thiscouldbeusbut we waited too long to get married (AP Photo/Rick Rycroft) Conventional wisdom has it that the older you are when you get married, the lower your chances for divorce. But a fascinating new analysis of family data by Nicholas H. Wolfinger, a sociologist at the University of Utah, suggests that after a certain point, the risk of divorce starts to rise again as you get older. Here's what that looks like in chart form: As you can see, the risk of divorce declines steadily from your teens into your late 20s, but somewhere in the early 30s it starts to creep back up again. As Wolfinger puts it: "Those who tie the knot after their early thirties are now more likely to divorce than those who marry in their late twenties." The chart is based on a statistical analysis of data from the National Survey of Family Growth, a nationally-representative survey administered by the CDC every few years. The greater divorce risk of younger couples makes some intuitive sense -- in your teens and early 20s, you're still figuring out who you are and what you want out of life. That person who was perfect for you at 19 may seem a lot less perfect by the time you're 30. But what about older couples? Let's say you wait until 40 to get married -- shouldn't you have a pretty good idea of what you want by then, making your risk of divorce lower? Wolfinger thinks there's a selection effect happening here -- some people who wait a long time to get married simply may not be the marrying type, for instance. "Perhaps people who marry later face a pool of potential spouses that has been winnowed down to exclude the individuals most predisposed to succeed at matrimony," Wolfinger writes. It's important to remember that we're just talking about statistical risk here. If you wait until your 40s to get married, your relationship is by no means doomed. And waiting until later in life is still a much wiser option that marrying early. Looking at the raw divorce rates, for instance, Wolfinger found that people who married at age 35 or greater had a 19 percent risk of divorce, compared to a 20 percent risk for those aged 20 to 24, and a 32 percent risk for those who married before they were 20. Another key point of context to note is that overall divorce rates are still on a 30-year decline from their peak in the early 1980s. But the important thing, for Wolfinger, is that "we do know beyond a shadow of a doubt that people who marry in their thirties are now at greater risk of divorce than are people who wed in their late twenties. This is a new development." And it will take some further research to suss out what this means for the demographics of marriage going forward.

– A standard line of advice about marriage these days is not to wed too young—and divorce stats about people getting hitched before age 20 back that up. But a new study out of the University of Utah adds a surprising twist: Don't wait too long, because the risk of divorce starts rising again in the early 30s, reports the Salt Lake Tribune. In sociologist Nicholas Wolfinger's stats, divorce rates steadily drop through the 20s and into the 30s—Vox sees a "sweet spot" in them for those getting married at ages 27 to 29—but then hit a tipping point at age 32. From then on, the risk of divorce starts ticking upward about 5% a year. "Those who tie the knot after their early thirties are now more likely to divorce than those who marry in their late twenties," is Wolfinger's big takeaway, per the Washington Post. He floats some theories, including one that people who wait until their late 30s or beyond to wed "face a pool of potential spouses that has been winnowed down to exclude the individuals most predisposed to succeed at matrimony." A post at Slate sums it up as the "Goldilocks theory" on marriage: "Getting married too early is risky, but so is getting married too late. Your late 20s and early 30s are just right." (Click to read about how much weight marriage packs on.)

SECTION 1. SHORT TITLE. This Act may be cited as the ``Minority Equity Capital Formation Act of 1993''. SEC. 2. FINDINGS AND PURPOSES. (a) Findings.--The Congress finds that-- (1) there is a severe shortage of capital available and targeted for investment in the United States minority business marketplace and that such shortage constitutes a ``capital gap''; (2) the capital gap is a significant barrier to increased minority entrepreneurship, employment, and economic development; (3) the development of targeted venture capital resources is an important and needed stimulus for economic development, employment growth, and wealth creation; (4) existing Federal incentives are inadequate to address the capital gap; (5) the existing system of federally regulated specialized small business investment companies (and similar public and private entities who support and invest in the minority small business marketplace) should be fully utilized to aggregate and efficiently deploy new capital investments; and (6) it is essential, and should be a high priority of the United States Government, to pursue a broad array of Federal tax and other domestic policies that will serve as a catalyst for the creation of capital pools for investment in the minority enterprise marketplace. (b) Purposes.--The purposes of this Act are to-- (1) authorize a Federal tax credit for investment in qualified minority fund interests; (2) increase the availability of venture capital for minority small business; (3) strengthen existing public and private minority venture capital financial institutions (as well as to encourage the formation of such new institutions); and (4) through these actions, support minority enterprise and economic development, increase minority entrepreneurship and employment, and to enhance the opportunities for minority persons to participate fully in the free enterprise system. SEC. 3. INCENTIVES FOR INVESTMENTS IN MINORITY VENTURE CAPITAL FUNDS. (a) General Rule.--Part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 (relating to credits against tax) is amended by adding at the end thereof the following new subpart: ``Subpart H--Incentives for Investments in Minority Venture Capital Funds ``Sec. 54. Credit for investment in minority venture capital funds. ``Sec. 54A. Recapture provisions. ``Sec. 54B. Definitions and special rules. ``SEC. 54. CREDIT FOR INVESTMENT IN MINORITY VENTURE CAPITAL FUNDS. ``(a) General Rule.--For purposes of section 38, the minority venture capital fund credit determined under this section is an amount equal to 20 percent of the aggregate bases of qualified minority fund interests which are acquired by the taxpayer during the taxable year at their original issuance (directly or through an underwriter) and which are held by the taxpayer at the end of the taxable year. ``(b) Limitations.--The credit determined under paragraph (1) for any taxable year shall not exceed the lesser of-- ``(1) $250,000 ($125,000 in the case of a separate return by a married individual), or ``(2) $7,000,000, ($3,500,000 in the case of a separate return by a married individual), reduced by the amount of the credit allowed under paragraph (1) for all preceding taxable years. ``SEC. 54A. RECAPTURE PROVISIONS. ``(a) Basis Reduction.-- ``(1) In general.--If a credit is determined under section 54(a) with respect to any qualified minority fund interest, the basis of such qualified minority fund interest shall be reduced by the credit so determined. ``(2) Certain dispositions.--If during any taxable year there is a recapture under subsection (c) with respect to any qualified minority fund interest, the basis of such interest (immediately before the event resulting in such recapture) shall be increased by an amount equal to the recapture amount. For purposes of the preceding sentence, the term `recapture amount' means any increase in tax under subsection (c) (or adjustment in carrybacks or carryovers under subsection (c)) to the extent attributable to the amount referred to in subsection (c)(1)(A). ``(b) Tax Credit Recaptured as Ordinary Income.-- ``(1) In general.--For purposes of section 1245-- ``(A) any property the basis of which is reduced under subsection (a) (and any other property the basis of which is determined in whole or in part by reference to the adjusted basis of such property) shall be treated as section 1245 property, and ``(B) any reduction under subsection (a) shall be treated as a deduction allowed for depreciation. If an exchange of any stock or partnership interest the basis of which is reduced under subsection (a) qualifies under section 351(a), 354(a), 355(a), or 356(a), the amount of gain recognized under section 1245 by reason of this paragraph shall not exceed the amount of gain recognized in the exchange (determined without regard to this paragraph). ``(2) Certain events treated as dispositions.--For purposes of this subsection and subsection (c), if a credit was determined under section 54 with respect to any stock in a corporation or interest in a partnership and such stock or partnership interest, as the case may be, ceases to be a qualified minority fund interest, the taxpayer shall be treated as having disposed of such property (as of the time of such cessation) for an amount equal to its fair market value. ``(c) Increase in Tax if Disposition Within 5 Years.-- ``(1) In general.--If a taxpayer disposes of any qualified minority fund interest before the close of the fifth taxable year after the taxable year in which such interest was acquired by the taxpayer, the tax imposed by this chapter for the taxable year in which such disposition occurs shall be increased by the sum of-- ``(A) the recapture percentage of the aggregate decrease in the credits allowed under section 38 for all prior taxable years which would have resulted solely from reducing to zero any credit determined under this subpart with respect to such interest, and ``(B) the interest amount determined under paragraph (3). ``(2) Recapture percentage.--For purposes of paragraph (1), the recapture percentage is-- ``(A) 100 percent if the disposition occurs during the first, second, or third taxable year after the taxable year in which the qualified minority fund interest was acquired, and ``(B) 50 percent if the disposition occurs in the fourth or fifth taxable year after the taxable year in which such interest was acquired. ``(3) Interest amount.--For purposes of paragraph (1), the interest amount determined under this paragraph is interest determined at the overpayment rate established under section 662(a)(2) (without regard to section 6621(c))-- ``(A) on the recapture percentage of each decrease in credit referred to in paragraph (1)(A) for any prior taxable year, ``(B) for the period beginning on the due date for such prior taxable year and ending on the due date for the taxable year in which the disposition occurs. For purposes of the preceding sentence, the term `due date' means the due date (determined without regard to extensions) for filing the return of the tax imposed by this chapter. ``(4) Carrybacks and carryovers adjusted.--In the case of any disposition described in paragraph (1), the carrybacks and carryovers under section 39 shall be adjusted by reason of such disposition. ``(5) Coordination with other credits, etc.--Any increase in tax under paragraph (1) shall not be treated as a tax imposed by this chapter for purposes of determining the amount of-- ``(A) any credit allowable under subpart A, B, D, or G, and ``(B) the minimum tax imposed by section 55. ``(6) Special rules.--For purposes of this subsection-- ``(A) Mere change in form.--A taxpayer shall not be treated as disposing of any qualified minority fund interest by reason of a mere change in the form of the taxpayer, the entity which issued such interest or any qualified minority business. ``(B) Exception for certain transfers.--Paragraph (1) shall not apply to any transfer by reason of death or in a transaction to which section 381(a) applies. ``SEC. 54B. DEFINITIONS AND SPECIAL RULES. ``(a) Qualified Minority Business Defined.--For purposes of this subpart-- ``(1) General rule.--The term `qualified minority business' means any domestic business if-- ``(A) 50 percent or more of the total value of the ownership interests in such business are held (directly or indirectly) by individuals who are members of a minority, ``(B) throughout the 5-year period ending on the date as of which the determination is being made (or, if shorter, throughout the period such business was in existence), such business has been engaged in the active conduct of a trade or business or in startup activities relating to a trade or business, and ``(C) substantially all of the assets of such business are being used in the active conduct of a trade or business or in startup activities related to a trade or business. ``(2) Domestic business.--For purposes of paragraph (1), the term `domestic business' means-- ``(A) any domestic corporation or domestic partnership, and ``(B) any trade or business conducted in the United States as a sole proprietorship. ``(b) Qualified Minority Fund Interest Defined.--For purposes of this subpart, the term `qualified minority fund interest' means any stock in a domestic corporation or partnership interest in a domestic partnership if-- ``(1) such stock or partnership interest (as the case may be) is issued after the date of the enactment of this subpart solely in exchange for money, ``(2) such corporation or partnership (as the case may be) was formed exclusively for purposes of-- ``(A) acquiring at original issuance (directly or through an underwriter) owner interests in qualified minority businesses, or ``(B) making loans to such businesses, and ``(3) at least 80 percent of the total bases of its assets is represented by-- ``(A) investments referred to in paragraph (2), and ``(B) cash and cash equivalents. ``(c) Minority Individuals.--For purposes of this subpart, individuals are members of a minority if the participation of such individuals in the free enterprise system is hampered because of social disadvantage within the meaning of section 301(d) of the Small Business Investment Act of 1958. ``(d) Controlled Group Rules.-- ``(1) In general.--All corporations which are members of the same controlled groups shall be treated as 1 corporation for purposes of this subpart. ``(2) Controlled group.--For purposes of paragraph (1), the term `controlled group' has the meaning given such term by section 179(d)(7).'' (b) Credit Made Part of General Business Credit.--Subsection (b) of section 38 of such Code is amended by striking ``plus'' at the end of paragraph (7), by striking the period at the end of paragraph (8) and inserting ``, plus'', and by adding at the end thereof the following new paragraph: ``(9) the minority venture capital fund credit determined under section 54.'' (c) Credit May Offset 25 Percent of Minimum Tax.--Subsection (c) of section 38 of such Code is amended by redesignating paragraph (2) as paragraph (3) and by inserting after paragraph (1) the following new paragraph: ``(2) Credit for investments in minority venture capital funds may offset 25 percent of minimum tax.-- ``(A) In general.--In the case of a C corporation, the amount determined under paragraph (1)(A) shall be reduced by the lesser of-- ``(i) the portion of the credit under section 54 not used against the normal limitation, or ``(ii) 25 percent of the taxpayer's tentative minimum tax for the taxable year. ``(B) Portion of the credit under section 54 not used against normal limit.--For purposes of subparagraph (A), the portion of the credit under section 54 for any taxable year not used against the normal limitation is the excess (if any) of-- ``(i) the portion of the credit under subsection (a) which is attributable to the credit under section 54, over ``(ii) the limitation of paragraph (1) (without regard to this paragraph) reduced by the portion of the credit under subsection (a) which is not so attributable. ``(C) Limitation.--In no event shall this paragraph permit the allowance of a credit which would result in a net chapter 1 tax less than an amount equal to 10 percent of the amount determined under section 55(b)(1)(A) without regard to the alternative tax net operating loss deduction. For purposes of the preceding sentence, the term `net chapter 1 tax' means the sum of the regular tax liability for the taxable year and the tax imposed by section 55 for the taxable year, reduced by the sum of the credits allowable under this part for the taxable year (other than under section 34).'' (d) Clerical Amendment.--The table of subparts for part IV subchapter A of chapter 1 of such Code is amended by adding at the end thereof the following item: ``Subpart H. Incentives for investments in enterprises owned by disadvantaged individuals.'' (e) Effective Date.--The amendments made by this section shall apply to taxable years ending after the date of the enactment of this Act.

Minority Equity Capital Formation Act of 1993 - Amends the Internal Revenue Code to allow a minority venture capital fund credit of 20 percent of the aggregate bases of qualified minority fund interests, with limitations. Sets forth recapture provisions for such stock. Makes such credit a part of the general business credit and allows it to offset a portion of the tentative minimum tax.

in recent years a number of unusual superconducting ( sc ) states have been discovered in different new materials @xcite . most of these materials are strongly type - ii superconductors , possessing highly anisotropic or even quasi - two - dimensional ( 2d ) electronic structures . of special interest in the present paper are sc materials showing peculiar clean - limit features at high magnetic fields and low temperatures , notably the recently discovered family of heavy - fermion compounds cerin@xmath0 ( r = rh , ir and co ) @xcite , and some of the organic charge transfer salts of the type ( bedt - ttf)@xmath1x @xcite,@xcite . the heavy - fermion compound cecoin@xmath0 , for example , which is believed to be an unconventional ( @xmath2-wave ) superconductor @xcite similar to the high - tc cuprates , exhibits the highest tc ( @xmath3 k ) among the ce - based heavy - fermion compounds . this material is characterized by exceptionally strong pauli paramagnetic pair - breaking @xcite , chandrasekhar62 due to its extremely large electron effective mass and small fermi velocity , which could lead to discontinuous ( first - order ) sc phase transitions at sufficiently high magnetic fields @xcite , maki64,@xcite . recently bianchi _ _ et.al.__@xcite have observed a dramatic changeover of the second - order sc phase transition to a first - order transition in specific heat measurements performed on this material as the magnetic field is increased above some critical values for both parallel and perpendicular field orientations with respect to the easy conducting planes . similar effect has been very recently observed by lortz _ et.al . _ @xcite in the nearly 2d organic superconductor @xmath4-(bedt - ttf)@xmath5cu(ncs)@xmath1 , but only for magnetic field orientation parallel to the superconducting layers , where the orbital ( diamagnetic ) pair - breaking is completely suppressed . under these conditions the usual ( uniform ) sc state is expected to be unstable with respect to formation of a nonuniform sc state , predicted more than 40 years ago by fulde and ferrel @xcite , and by larkin and ovchinikov @xcite ( fflo ) . the corresponding sc order parameter is spatially - modulated along the field direction with a characteristic wavenumber , @xmath6 , whose kinetic energy cost is compensated by the pauli pair - breaking energy . the critical temperature , @xmath7 , for the appearance of the fflo phase is found to equal @xmath8 . at the corresponding tricritical point the normal , the uniform and non - uniform sc phases are all met . the possibility of a changeover to first - order transitions can be effectively investigated within the ginzburg - landau ( gl ) theory of superconductivity since for the uniform sc phase ( i.e. for @xmath9 ) the coefficient ( usually denoted by @xmath10 ) of the quartic term in the gl expansion changes sign at a temperature @xmath11 , which coincides with @xmath12 @xcite . the identity of @xmath11 with @xmath7 is peculiar to the clean limit of a superconductor with no orbital pair - breaking . in conventional s - wave superconductors electron scattering by non - magnetic impurities shifts @xmath7 below the critical temperature @xmath13 @xcite , allowing discontinuous phase transitions at temperatures @xmath14 , since ( following anderson s theorem ) @xmath10 is not influenced by nonmagnetic impurities . in superconductors with unconventional electron pairing , where @xmath10 is strongly influenced by non - magnetic impurity scattering , the situation is reversed , i.e. @xmath15 . the interplay between orbital and spin depairing in a pure @xmath16-wave isotropic 3d superconductor was first discussed by gruenberg and gunthergruenberg66 , who conjectured ( i.e. without presenting any result for the coefficient @xmath10 ) that for @xmath17 the n - sc transition is of the second order whereas at lower field there should be a first - order transition to a uniform sc phase . houzet and buzdin@xcite have essentially confirmed this picture by exploiting order - parameter and gradient expansions in the gl theory to find that @xmath15 so that at temperatures @xmath18 , there are second order transitions to either the lo or ff phase . it should be noted , however , that the orbital effect was treated there by using gradient expansions , which is a valid approximation only at very low magnetic fields . in contrast to all the works outlined above , adachi and ikeda have recently found @xcite that , in a clean , @xmath2-wave , 2d ( layered ) superconductor , the orbital effect always shifts @xmath7 below @xmath11 . in this work the authors have used order parameter expansion in the gorkov green s function approach to the gl theory up to six order , avoiding the restrictions of gradient expansion by exploiting the lowest landau level ( lll ) approximation for the condensate of cooper - pairs . accounting for impurity scattering destroys the fflo phase and , in contrast to the pure paramagnetic situation , somewhat reduces @xmath11 . the effect of sc thermal fluctuations was found in this work to broaden the discontinuous mean - field transition at @xmath11 into a crossover . the reliance on ( fflo ) wavenumber expansion and on extensive numerical computations in this work has saved formidable analytical efforts , leaving however , interesting questions unanswered . in particular , the origin of the relative shift of @xmath12 below @xmath11 by the orbital effect found in this work , in contrast to all the other works , remains unknown . in the present paper we develop a formalism based on order parameter expansion within the gorkov theory for a strongly type - ii superconductor , with both @xmath16- and @xmath19-wave electron pairing at high magnetic fields , which is sufficiently simple to yield useful analytical expressions for the sc free energy to any desired order in the expansion . the fundamental interplay between spin induced paramagnetic and orbital diamagnetic effects at an arbitrary magnetic field is studied , within a model of anisotropic electron systems covering the entire 3d-2d crossover range , without relying on gradient or wavenumber expansions . these advantages enable us to shed new light on the yet undecided debate concerning the order of the sc phase transitions in the presence of strong zeeman spin splitting , and to push our investigation into the unexplored region of very low temperatures , where quantum magnetic oscillations have been shown to be observable in the heavy fermion compounds settai02,shishido03 . specifically , it is found that the relevant parameter controlling the relative position of @xmath7 with respect to @xmath11 is the dimensionality of the electronic orbital motion in the crystal lattice , through its influence on the orbital ( diamagnetic ) pair - breaking effect . for a 3d fermi surface ( isotropic or anisotropic ) , where the electron motion along the magnetic field direction reduces the cyclotron kinetic energy , the shift of @xmath11 to low temperatures is larger than that of @xmath7 . in this case the kinetic energy of cooper - pairs associated with their motion along the field can compensate the spin - splitting effect , and thus leading to an increase of @xmath10 and disappearance of the first - order transition . the corresponding phase diagram is similar to that suggested in ref . gruenberg66 , where the n - sc transition is of second order , whereas the transition between non - uniform and uniform ( along the field ) sc states is of first order . in the quasi-2d limit ( i.e. for quasi - cylindrical fermi surfaces ) the enhanced orbital pair - breaking shifts @xmath7 below @xmath13 , in agreement with adachi and ikeda @xcite . our starting point is an effective bcs - like hamiltonian with a @xmath20-wave pairing interaction similar to that exploited , e.g . by agterberg and yang @xcite . the conventional @xmath16-wave situation can be similarly worked out and so will not be presented in detail here . the thermodynamical potential ( per unit volume ) for the corresponding @xmath2-wave superconductor , as expanded in the order parameter with nonlocal normal electron kernels , may be written as : @xmath21where @xmath22 is a functional of the sc order parameter , @xmath23 , having a power - low dependence @xmath24 on the global amplitude , @xmath25 , of the order parameter , and @xmath26 is a bcs coupling constant ( given in units of energy@xmath27 volume ) . the corresponding @xmath2-wave order parameter depends on both the center of mass ( @xmath28 ) and relative ( @xmath29 ) coordinates of a condensate of electron pairs : @xmath30 . it should be determined self - consistently from the corresponding pair - correlation functions . only stationary solutions are considered , neglecting quantum and thermal fluctuations . in addition the order parameter in the mean field approximation is selected as a hexagonal vortex lattice . actually this assumption is not very important since the second order term in the order parameter expansion does not depend on the vortex lattice structure whereas the lattice structure dependence of the quartic term is very weak ( for reviews see @xcite , mrvw92 ) . for the underlying system of normal electrons we assume a simple model of quadratic energy dispersion @xmath31 and anisotropic effective mass tensor : @xmath32 . a quasi-2d situation is characterized by a sufficiently large anisotropy parameter @xmath33 , corresponding to an elongated fermi surface with a fermi momentum @xmath34 and fermi energy @xmath35 , which is truncated by the brillouin zone ( bz ) face at @xmath36 , where @xmath2 is the lattice constant perpendicular to the easy planes . a parameter determining the dimensionality of the fermi surface may be defined by : @xmath37 , where @xmath38 is the maximal value of the electron energy along the field . thus , in the 2d limit , @xmath39 , we have @xmath40 , while the system may be regarded 3d ( isotropic or anisotropic ) if @xmath41 for which the fermi surface is contained entirely within the first bz , namely for @xmath42 . at any order of the expansion , eq.([opexpan ] ) , the nonlocal electronic kernel of the corresponding functional ( see e.g. eqs . ( [ omega_gen]),(kernel_2 ) , and eqs . ( [ omega4_def]),([k4_def ] ) ) consists of a product of @xmath43 pairs of normal electron green s functions in a constant magnetic field,@xmath44 ( i.e. perpendicular to the easy conducting layers ) , which are written in the form : @xmath45 , where the gauge factor is given by@xmath46 \cdot \widehat{z}% } $ ] , @xmath47 , and the gauge invariant part can be calculated by the well known expression@xcite @xmath48 here @xmath49 with @xmath50 is matzubara frequency , @xmath51 , @xmath52 , the spin - split normal electron energy levels , @xmath53-the in - plane electronic cyclotron frequency , @xmath54is a dimensionless longitudinal ( parallel to the magnetic field ) kinetic energy , @xmath55 , is the zeeman spin splitting energy , @xmath56- the impurity scattering relaxation rate , and @xmath57 is the chemical potential . the spatial variables are dimensionless in - plane ( perpendicular to the magnetic field ) coordinates , @xmath58 , and longitudinal coordinates:@xmath59 , and @xmath60 . in the expansion , eq.([opexpan ] ) , the second order term , which describes the sc condensation energy of spin - singlet electron - pairs , propagating from initial ( @xmath61 ) to final ( @xmath62 ) coordinates @xmath63 , is given by : @xmath64where @xmath65 is the volume of the system . the vertex part , @xmath66 is a product of two order parameters multiplied by the gauge factors , @xmath67 , which are functions of the center of mass coordinates only , due to cacellation by the corresponding phase factors of the order parameters , namely:@xmath68the kernel @xmath69 is a product of two translational invariant green s functions , convoluted with the corresponding factors of the order parameters , which depend only on the relative pair coordinates , namely : @xmath70 the factor of the order parameter which depends on the pair center of mass coordinates is written as@xcite:@xmath71where @xmath72 is the fulde - ferrell modulation factor . exploiting the fact that the kernel @xmath73 depends only on the difference @xmath74 , one may carry out the integration in eq.([omega_gen ] ) first over the in - plane mean coordinates @xmath75 to get the following average vertex part @xcite @xmath76where @xmath77 ( @xmath65 ) , and then integrate over the rest of the coordinates @xmath78 and @xmath79 . since , among other things , we are interested in the effect of quantum magnetic oscillations , we apply a technique of exact summation over lls suggested in ref.@xcite . it is similar to the poisson summation formula , which transforms the summation over lls into summation over harmonics of the inverse magnetic field , and allows to deal seperately with the uniform ( quasi - classical ) contribution and the various quantum corrections . this technique can be briefly described as follows . let us consider the integral representation of the green s functions , @xmath80 ^{-1}=\int_{0}^{\infty } d\tau e^{\pm i\tau % \left [ n_{f}-n - x^{2}\pm i\omega \right ] } $ ] and perform the summation over lls using the well known identity , @xmath81 with @xmath82 and @xmath83 . taking advantage of these relations the gauge invariant part of the green s function for @xmath84 can be transformed to:@xmath85 } } { % \left ( 1-e^{-i\tau } \right ) } \exp \left ( \frac{\rho ^{2}}{4}\frac{1+e^{i\tau } } { 1-e^{i\tau } } \right ) \label{greenfunc_tau}\]]where @xmath86 , @xmath87 . for @xmath88 one should replace @xmath89 with @xmath90 ( or @xmath91 with @xmath92 ) . the scattering of electrons by non - magnetic impurities is taken into account here as a self - energy correction to the single electron green s functions using the standard relaxation time approximation . vertex corrections to the quadratic kernel @xmath93 ( as well as to higher order ones ) , which are known to exactly cancel the self - energy insertions in the very weak magnetic field regime of convensional s - wave superconductors ( see e.g. @xcite ) , are not so crucial in the strong magnetic field regime of both the s and d - wave situations investigated here , and will be therefore neglected in our calculations , as done , e.g. in refs.@xcite . in any event , for the high magnetic field and relatively clean superconductors considered here , the length scale , @xmath94 , corresponding to the diamagnetic pair - breaking is much smaller than the electron mean free path @xmath95 , and the effect of impurity scattering is marginal . utilizing this approximation we rewrite the kernel in the following form : @xmath96 } \int_{0}^{\infty } d\tau _ { 2}e^{-i\tau _ { 2}\left [ n_{f}-\xi ^{2}k_{z,2}^{2}-g - i\widetilde{\omega } _ { \nu } -i\widetilde{\gamma } \right ] } j\left ( \tau _ { 1},\tau _ { 2,}\mathbf{\rho } \right ) \notag\end{aligned}\]]where @xmath97 @xmath98 , @xmath99 , and@xmath100 in eq.([kernel2 ] ) we use the representation @xmath101 , where @xmath102 describes the two types of the electron pairing , the symmetric @xmath16-wave pairing with@xmath103and @xmath19-wave pairing,@xmath104producing nodes in the order parameter along the @xmath105 directions . the @xmath106-dependence on @xmath107 enables us to readily perfom the first two integrations in eq . ( [ kernel2 ] ) . using the resulting expression for @xmath108 , and the vertex function @xmath109 one can calculate the nontrivial coefficient @xmath110 in eq.([omega_gen ] ) by performing the integrals over @xmath111,and @xmath112 @xmath113with the other integrals incorporated in the kernel as appearing in eq.(kernel2 ) . it is convenient to perform the integration over @xmath111 first since both the function @xmath114and the vertex part have a gaussian dependence on @xmath111 which can be readily carried out with the result:@xmath115where@xmath116and @xmath117 . it should be noted here that the type of pairing influences the sc condensation energy through the functional dependence of @xmath118 on the pairing function @xmath119 . performing the straightforward calculation of @xmath120 for both functions one obtains,@xmath121@xmath122where the last approximate step is obtained in the limit @xmath123 this can be justified by noting that the scale of the function @xmath124 is of the order unity whereas @xmath2 ( in units of the magnetic length ) is much smaller than one . in the opposite limit : @xmath125**. * * thus , noting that the integration of * * * * @xmath110 * * * * over the center of mass coordinates yields just the total volume of the system , and performing the integration over the relative coordinate @xmath126,@xmath127 } e^{-i\tau _ { 2}\left [ n_{f}-\xi ^{2}k_{z,2}^{2}-g - i\widetilde{\omega } _ { \nu } -i\widetilde{\gamma } \right ] } e^{-iq\rho _ { z } } \notag \\ & = & \int \frac{dk_{z}}{2\pi } \ e^{i\tau _ { 1}\left [ n_{f}-\xi ^{2}\left ( k_{z}+q/2\right ) ^{2}+g+i\widetilde{\omega } _ { \nu } + i\widetilde{\gamma } % \right ] } e^{-i\tau _ { 2}\left [ n_{f}-\xi ^{2}\left ( k_{z}-q/2\right ) ^{2}-g - i% \widetilde{\omega } _ { \nu } -i\widetilde{\gamma } \right ] } , \label{kz_integ}\end{aligned}\]]one obtaines for a @xmath2-wave superconductor:@xmath128 } e^{-i\tau _ { 2}\left [ n_{f}-\xi ^{2}\left ( k_{z}-q/2\right ) ^{2}-g - i\widetilde{\omega } % _ { \nu } -i\widetilde{\gamma } \right ] } } { \left ( 2-e^{-i\tau _ { 1}}-e^{i\tau _ { 2}}\right ) ^{3}}. \notag\end{aligned}\ ] ] a similar expression can be derived for an @xmath16-wave superconductor . below we will present only the final result for this case ( _ _ _ _ see eqs . * * [ a0_fin]*,*[theta_s]*)*. eq . ( [ a0_d1 ] ) is an _ exact _ representation for the coefficient of the quadratic term in the order parameter expansion , eq.[omega_gen ] , which includes low temperature quantum corrections and quantum magnetic oscillations . it can be written as a sum of contributions from poles at the 2d lattice : @xmath129 and @xmath130 , with @xmath131 . the dominant ( zero harmonic ) quasiclassical contribution arises from the pole at @xmath132 whereas the quantum corrections are associated with the poles at @xmath133 . it is easy to see that the oscillating terms correspond to the off - diagonal poles , @xmath134 , in the @xmath135-plane . in the present paper we are interested mainly in the quasiclassical contribution for which a further simplification can be achieved . changing to new variables : @xmath136 @xmath137 , and exploiting the expansion @xmath138 near the `` quasiclassical '' pole @xmath139 , one carries out the integral over @xmath89 in eq . ( [ a0_d1 ] ) to have:@xmath140 } \notag \\ & & \times \left [ n_{f}-\xi ^{2}\left ( k_{z}^{2}+\left ( q/2\right ) ^{2}\right ) % \right ] ^{2}e^{-\rho _ { 0}^{2}\left [ n_{f}-\xi ^{2}\left ( k_{z}^{2}+\left ( q/2\right ) ^{2}\right ) \right ] } \label{a0_d2}\end{aligned}\]]note that the lowest order expansion of the denominator in eq.([a0_d1 ] ) about @xmath139 is kept under the entire range of integration since the important integration inerval is of the order @xmath141 . note also that throughout this paper we assume that @xmath142 . it is convenient to rescale variables as@xmath143and neglect the energy of an electron pair along the @xmath107-axis , @xmath144 , with respect to fermi energy , @xmath145 . perfoming the explicit summation over matsubara frequencies one obtains , in terms of the new variables , the following result:@xmath146where @xmath147 , @xmath148 is the electron density of states per spin at the fermi energy ` ( ` @xmath149 ) , and : @xmath150 a similar result is obtained for an @xmath16-wave superconductor . in this case @xmath151 and @xmath152for @xmath153 eqs . ( [ a0_fin])([theta_s ] ) reduces to the quadratic term derived by helfand - werthammer @xcite . the quartic term in the perturbation expansion , eq.([opexpan ] ) , which corresponds to a closed loop diagram with four vertices , is given by:@xmath154where the kernel , containing the gauge invariant factors of the four electron green s functions , is : @xmath155@xmath156and the vertex part : @xmath157which consists of the gauge factors @xmath158 and the order parameter values at the four center of mass positions for two electron pairs . since the dependence of the order parameter on the relative pair coordinates is separable from that of the center of mass coordinates , the latter dependence is selected to have the usual abrikosov lattice structure,@xmath159with @xmath160 and @xmath161 , . to simplfy the calculation of the vertex part we exploit several assumptions . substituting eq.(delta_comp ) to eq.([gamma4_def ] ) , one may keep only diagonal terms with @xmath162 , since all off - diagonal terms are small by the gaussian factor @xmath163 $ ] . furthermore , we may replace summation over @xmath164 with an appropriate integration . both of these assumptions are equivalent to neglecting particular vortex lattice structures , corresponding to replacement of the abrikosov structure parameter , @xmath165 , with @xmath166 @xcite , which yields only a small error . with the above assumptions the vertex part reduces to : @xmath167 } \label{gamma4_comp}\]]where @xmath168 . since the dominant contribution to the quartic term arises from small propagation distances , @xmath169@xcite , one may expand the last exponential on the rhs of eq.([gamma4_comp ] ) , up to leading order , under the integrals over angular variables in eq.([omega4_def ] ) . additional angular dependence is due to the kernel , @xmath170 , through its dependence on the absolute values of linear combinations of `` external '' , @xmath171 , and `` internal '' , @xmath172 ( @xmath173 ) , coordinates ( see eq . [ k4_def ] ) . since the characteristic size of @xmath174 is much smaller than the scale of @xmath175 , the dependence of the kernel on @xmath172 ( and consequently its dependence on the angular variables ) may be neglected at large @xmath176 . therefore , the integration over angular variables in this region involves only the last exponential in eq.([gamma4_comp ] ) , resulting in : @xmath177 } \right\rangle & \approx & 1+% \frac{1}{4}\left\langle \left ( u_{1}-u_{3}\right ) ^{2}+\left ( u_{2}^{\ast } -u_{4}^{\ast } \right ) ^{2}\right\rangle = 1 , \\ \text{since \ } \left\langle u_{l}^{2}\right\rangle & = & \left\langle u_{l}u_{k}^{\ast } \right\rangle = 0\ , \ \left ( l\not = k\right)\end{aligned}\]]whereas for small values of @xmath178 this exponential is always close to @xmath179 and the remaining integration over angular variables can be perfomed in closed form ( see below ) . thus , one can approximate the vertex part by the following simple expression:@xmath180which depends only on nearest neighboring coordinates . making use of eq.([gamma4_fin ] ) , the remaining calculation of the quartic term is similar to that used for the quadratic term , but considerably massier . below we present only an outline of the derivation . since integrations over @xmath181 are trivial we shall use from now on only 2d vector notations with integrations over @xmath182 written explicitly . combining eqs.([omega4_def]),([k4_def]),([gamma4_fin ] ) our starting expression for the quartic term is given by:@xmath183@xmath184@xmath185where the function @xmath186 includes integration over all electron pair coordinates : _ _ _ _ @xmath187@xmath188 } \frac{\exp \left ( \frac{r_{12}^{2}}{4}\frac{1+e^{-i\tau _ { 1}}}{1-e^{-i\tau _ { 1}}}\right ) } { % 1-e^{i\tau _ { 1}}}\int_{0}^{\infty } d\tau _ { 2}e^{i\tau _ { 2}\left [ n_{f}-x_{2}^{2}+g+i\widetilde{\omega } _ { \nu } + i\widetilde{\gamma } \right ] } % \frac{\exp \left ( \frac{r_{23}^{2}}{4}\frac{1+e^{i\tau _ { 2}}}{1-e^{i\tau _ { 2}}}\right ) } { 1-e^{-i\tau _ { 2}}}\times\]]@xmath189 } \frac{\exp \left ( \frac{r_{34}^{2}}{4}\frac{1+e^{-i\tau _ { 3}}}{1-e^{-i\tau _ { 3}}}\right ) } { % 1-e^{i\tau _ { 3}}}\int_{0}^{\infty } d\tau _ { 4}e^{i\tau _ { 4}\left [ n_{f}-x_{4}^{2}+g+i\widetilde{\omega } _ { \nu } + i\widetilde{\gamma } \right ] } % \frac{\exp \left ( \frac{r_{41}^{2}}{4}\frac{1+e^{i\tau _ { 4}}}{1-e^{i\tau _ { 4}}}\right ) } { 1-e^{-i\tau _ { 4 } } } \label{theta4_def}\]]here the coordinates , @xmath190 , in eq.([theta4_def ] ) are the linear combinations of @xmath191 and @xmath192 : @xmath193the gaussian integration over @xmath194 reduces eq . ( theta4_def ) to : @xmath195\]]@xmath196 } e^{i\tau _ { 2}\left [ n_{f}-x_{2}^{2}+g+i% \widetilde{\omega } _ { \nu } + i\widetilde{\gamma } \right ] } e^{-i\tau _ { 3}\left [ n_{f}-x_{3}^{2}-g - i\widetilde{\omega } _ { \nu } -i\widetilde{\gamma } \right ] } e^{i\tau _ { 4}\left [ n_{f}-x_{4}^{2}+g+i\widetilde{\omega } _ { \nu } + i% \widetilde{\gamma } \right ] } \label{theta4}\]]where @xmath197 . it should be noted here that eq.([theta4 ] ) has been obtained by exploiting the fact that the dominant contributions to the integrals originate in the regions where @xmath198 . furthermoe , noting that in the above equation the @xmath199- and @xmath200-dependences are factorized , one can perfom the integrations over both sets of variables separetely . for a @xmath2-wave superconductor we obtain : @xmath201\]]@xmath202where the last appoximation is valid under the same conditions discussed in the derivation of the quadratic term . thus the quartic term is transformed to:@xmath203@xmath204where an additional integration over @xmath205 for small @xmath206 can be performed . rescaling variables as@xmath207and summing up over @xmath208 one obtain the final result for the quartic term:@xmath209where @xmath210 with @xmath211 , @xmath212 , and @xmath213 the result for an @xmath16-wave superconductor can be obtained from eq.(omega4_fin ) by replacing the factor @xmath214 in the definition of @xmath215 and the factor @xmath216 in the normalization coefficient @xmath217 with unity . the @xmath16-wave quartic term for zero spin splitting is equivalent to that obtained in ref.mrvw92 . the analysis presented in the previous sections enables us to write a gl - like expansion of the sc contribution to the thermodynamic potential for an @xmath16 or @xmath19- wave pairing up to second order in @xmath218:@xmath219 for the quadratic term we have : @xmath220 \label{alpha}\end{aligned}\]]where @xmath221 , @xmath222 , with @xmath223 the debye temperature , and @xmath224-the inplane fermi velocity , @xmath225- the thermal mean - free path , @xmath226- the electronic cyclotron radius at the fermi energy , and @xmath227 is the mean - free path due to impurity scattering . the differences between @xmath16-wave and @xmath2-wave scs are given by @xmath228 , @xmath229 , and @xmath230 , @xmath231 . the quartic term has a similar structure:@xmath232 \left ( \int_{0}^{\rho /\sqrt{2}a_{h}}dse^{-s^{2}\left ( 1-v^{2}\right ) } \right ) ^{2 } \notag\end{aligned}\]]where @xmath233 and @xmath234 , @xmath235 , @xmath236 , and @xmath237 . on the basis of the above formulas we discuss below the h - t phase diagram for different values of the relevant parameters . three independent dimensionless parameters:@xmath238 , @xmath239 and @xmath240 , control the basic integrals in these equations . the first two parameters measure the strength of the spin and thermal pair - breaking mechanisms , respectively , relative to the orbital ( diamagnetic ) depairing . the third parameter determines the relative strength of the compensating fflo mechanism . the value of the spin pair - breaking parameter , @xmath241 , where @xmath242 is the upper critical field at @xmath243 in the absence of spin pair - breaking , is related to the well known maki parameter @xcite , @xmath244 , by : @xmath245 . here @xmath246 is the transition temperature at zero magnetic field . .,width=264 ] ( dashed lines ) , @xmath247(solid lines ) , @xmath248(doted lines ) as functions of the parameter @xmath249 for ( a ) @xmath250 and ( b ) @xmath251 . , width=264 ] as we shall show below , the situation @xmath252 , where @xmath11 is the temperature at which @xmath253 , is realized in 3d systems ( corresponding to @xmath42 ) , regardless of the spin - splitting strength and the type of electron pairing . a typical phase diagram is shown in fig . 1 for @xmath16-wave pairing and spin pair - breaking parameter @xmath254 . ( orange ) and the mean field sc free energy , @xmath255 ( blue ) , on the modulation paramer , @xmath256 , in a 3d system ( @xmath42 ) , at @xmath257 , @xmath258 , i.e. near the tricritical point , just below the normal - nonuniform sc transition . it is seen that @xmath259 in a small region around @xmath260 where the sc free energy has a minimum . the value of the spin splitting parameter is @xmath261 . ( b ) : the same as in ( a ) but for a slightly lower field , @xmath262 , where a uniform ( @xmath9 ) metastable sc state is present . ( c ) : the same as in ( b ) but for a slightly lower field , @xmath263 , where a uniform ( @xmath9 ) equilibrium sc state is present , while a metastable sc state exists at @xmath264.,title="fig:",width=226 ] + ( orange ) and the mean field sc free energy , @xmath255 ( blue ) , on the modulation paramer , @xmath256 , in a 3d system ( @xmath42 ) , at @xmath257 , @xmath258 , i.e. near the tricritical point , just below the normal - nonuniform sc transition . it is seen that @xmath259 in a small region around @xmath260 where the sc free energy has a minimum . the value of the spin splitting parameter is @xmath261 . ( b ) : the same as in ( a ) but for a slightly lower field , @xmath262 , where a uniform ( @xmath9 ) metastable sc state is present . ( c ) : the same as in ( b ) but for a slightly lower field , @xmath263 , where a uniform ( @xmath9 ) equilibrium sc state is present , while a metastable sc state exists at @xmath264.,title="fig:",width=226 ] + ( orange ) and the mean field sc free energy , @xmath255 ( blue ) , on the modulation paramer , @xmath256 , in a 3d system ( @xmath42 ) , at @xmath257 , @xmath258 , i.e. near the tricritical point , just below the normal - nonuniform sc transition . it is seen that @xmath259 in a small region around @xmath260 where the sc free energy has a minimum . the value of the spin splitting parameter is @xmath261 . ( b ) : the same as in ( a ) but for a slightly lower field , @xmath262 , where a uniform ( @xmath9 ) metastable sc state is present . ( c ) : the same as in ( b ) but for a slightly lower field , @xmath263 , where a uniform ( @xmath9 ) equilibrium sc state is present , while a metastable sc state exists at @xmath264.,title="fig:",width=226 ] + @xmath265 as long as @xmath266 ( so that @xmath267 ) the normal to sc ( n - sc ) phase transition is of second - order and the ( reduced ) critical field , @xmath268 , can be determined as the maximal value of @xmath269 obtained from the equation @xmath270 for all values of @xmath6 , at the ( reduced ) temperature @xmath271 . the solution of this equation for @xmath9 yields a transition line , @xmath272 , ignoring the possibility of a fflo state . the tricritical point , @xmath7 , is defined as the maximal temperature at which @xmath273 . it can alternatively be determined from the equation @xmath274 , which is equivalent to the condition for vanishing of the coefficient of @xmath275 in a gradient expansion of the sc free energy@xcite . for @xmath276 and sufficiently strong spin pair - breaking there can be a changeover to first - order sc transitions , but since @xmath277 ( see fig.2 ) , the segment of the @xmath268-line with first order transitions arises only at very low temperatures . for moderate @xmath278 values the coefficient @xmath279 at optimal @xmath6is always positive and the n - sc transition is of the second order at arbitrarily low temperature . the transition within the sc region from the nonuniform ( fflo ) to uniform ( bcs ) phase at @xmath266 can not be obtained just by analyzing the quadratic term @xmath280 since the sc order parameter is finite there . it can be obtained by minimizing the sc free energy ( including both quadratic and quartic terms ) with respect to the modulation wave number @xmath6 . neglecting the sixth and higher order terms in the expansion , the corresponding ( standard ) gl free energy , @xmath281 , ( @xmath282 being the heaviside step function ) , which has a single minimum at @xmath264 for field near @xmath283 ( see fig . 3a ) , developes a double - well structure ( see fig . 3b ) as a function of @xmath6 upon decreasing the field below @xmath283 at a given temperature @xmath284 ( due to the symmetry @xmath285 only positive values may be considered ) . one of these minima is always at @xmath9 , and it becomes energetically favorable at a critical field for a first order phase transition from the fflo to the uniform bcs phase . the second ( metastable ) minimum at @xmath264 disappears completely upon further field decrease ( see fig . 3c ) . ( green ) and @xmath286 ( blue ) , and the mean field sc free energy ( orange ) as functions of the modulation parameter , @xmath265 , in a 3d system ( @xmath42 ) at a relatively low temperature @xmath287 and decreasing field values ( a ) @xmath288 and ( b ) @xmath289 . note the vanishing of @xmath286 inside the region where @xmath259 , around which the used approximation , @xmath290 , for @xmath291 breaks down ( dashed sector of the orange line ) . , title="fig:",width=226 ] + ( green ) and @xmath286 ( blue ) , and the mean field sc free energy ( orange ) as functions of the modulation parameter , @xmath265 , in a 3d system ( @xmath42 ) at a relatively low temperature @xmath287 and decreasing field values ( a ) @xmath288 and ( b ) @xmath289 . note the vanishing of @xmath286 inside the region where @xmath259 , around which the used approximation , @xmath290 , for @xmath291 breaks down ( dashed sector of the orange line ) . , title="fig:",width=226 ] + @xmath265 at temperatures @xmath284 below @xmath11 the first two terms in the expansion of the thermodynamic potential are not sufficient to correctly describe the uniform sc state since for negative @xmath10- values the scale of the sc free energy is determined by the sixth order term . ` ` in contrast , the free energy of the nonuniform state , where @xmath292 , can be obtained from the stantard gl functional ( with the assumption that the contribution of the sixth order term is small compared to that of the quartic term ) . the characteristic @xmath6-dependences of the gl coefficients , @xmath293 and @xmath10 , and the mean field free energy @xmath294 , for @xmath295 are illustrated in fig . 4 . ` ` whereas at high fields ( fig . 4a ) the minimum of the sc energy occurs in a region where @xmath296 , at lower fields ( see fig . 4b ) it approaches the expanding temperature domain of negative @xmath10 . ` ` thus , even for moderate spin splitting and low temperature the transition line from the nonuniform to uniform sc state can not be determined without knowing the sixth - order term . it is clear , however , that this transition is of the first order . it should be noted that if one attempts to determine the fflo - bcs phase boundary from the equation @xmath297 it will greatly overestimate the size of the fflo phase as compared to that obtained by minimizing @xmath298 ( see fig . this remarkable difference is due to the strong @xmath299-dependence of the quartic coefficient @xmath10 ( see fig.2 ) . the suppression of the orbital effect in the considered 3d systems , with ellipsoidal fermi surfaces contained entirely within the bz , is due to the factor @xmath300 appearing in the gaussian exponents of eqs . ( [ alpha]),([beta ] ) . the recovery of this effect in quasi-2d systems with truncated ellipsoidal fermi surface , where @xmath301 , can reverse the relation between @xmath7 and @xmath11 . fig . 2b , where the gl coefficients are shown for @xmath302 , @xmath250 and @xmath16-wave pairing , illustrates the situation with @xmath303 , which occurs for all values of @xmath304 below a critical dimensionality @xmath305 ( see fig . 5 ) , and depends only weakly on the spin - splitting parameter @xmath278 . of the equation @xmath306 , corresponding to @xmath11 ( dashed line ) , and the equation @xmath307 , corresponding to @xmath7 ( solid line ) vs the dimensionality crossover parameter @xmath304 for @xmath308.,width=226 ] , and the dotted - dashed line can be obtained from @xmath309.,width=264 ] the corresponding phase diagram ( see fig . 6 ) for @xmath304 below this crossing point is quite different from that found for the 3d systems shown in fig.1 . first of all , since @xmath310 , one may use eqs . ( [ alpha]),([beta ] ) to determine the phase diagram only under the assumption that the sixth order coefficient @xmath311 is positive ( see ref.@xcite ) . in this case a discontinuous sc transition occurs at @xmath312 with @xmath313 and @xmath314 , and the corresponding critical field , @xmath315 , should be larger than @xmath316 , obtained from the equation @xmath317 . thus , at a temperature below @xmath11 , the n - sc phase boundary includes a segment of first order transitions , which may end at zero temperature , or at a finite temperature , depending on the spin - splitting strength . this dependence appears because of the competition between the decreasing explicit dependence of @xmath10 on decreasing temperature and its increasing implicit dependence through @xmath318 at the fflo state . the boundary between the bcs and fflo states should be determined by minimizing the free energy , eq . ( [ omega ] ) , with respect to @xmath6 . this may be restricted to the explicit dependence on @xmath6 since the order parameter is determined by : @xmath319 . consequently the positive sign of @xmath320 ( see fig . 2b ) results in partial cancellation of the leading contribution to @xmath321 , which is proportional to @xmath322 and negative in the fflo part of the phase diagram . moreover , since for the discontinuous transition the order parameter is finite just below the transition the higher order terms in @xmath323 ( eq . ( [ omega ] ) ) should be taken into account . as a result @xmath7 should be smaller than @xmath324- the temperature obtained from the equation @xmath325 @xmath326 , as schematically shown in fig . it is shown that the expected changeover to first - order sc transitions in clean , strongly type - ii superconductors in the pauli paramagnetic limit can take place only in materials with quasi - cylindrical fermi surfaces , regardless of the type of the electron ( s or d - wave ) pairing interaction which leads to superconductivity . this finding clarifies the confusing current literature on this topic@xcite,@xcite , adachi03 . the observation of such a changeover in the heavy fermion compound cecoin@xmath327 for magnetic field orientation perpendicular to the easy conducting plane@xcite is consistent with the quasi-2d character of its electronic band structure @xcite . the interesting situation of a 2d superconductor under a magnetic field parallel to the conducting plane , for which a changeover to discontinuous sc transitions was reported very recently@xcite , is more subtle since the vanishingly small cyclotron frequency characterizing this case does not allow utilization of the landau orbitals approach employed here ( for a recent review see , e.g.matsuda-shimahara07 ) . * acknowledgements * : this research was supported by the israel science foundation founded by the academy of sciences and humanities , by the argentinian research fund at the technion , and by euromagnet under the eu contract rii3-ct-2004 - 506239 .

superconducting phase transitions in strongly type - ii superconductors in the pauli paramagnetic limit are considered within the framework of the gorkov - ginzburg - landau approach in the lowest landau level approximation for both s and d - wave electron pairing . simple analytical expressions for the quadratic and quartic coefficients in the order parameter expansion of the superconducting free energy are derived without relying on gradient or wavenumber expansions . the existence of a changeover from continuos to discontinuos superconducting phase transitions predicted to occur in the clean limit is shown to depend only on the dimensionality of the underlying electronic band structure . such a changeover can take place in the quasi 2d regime below a critical value of a 3d-2d crossover parameter .

supersolidity is a unique state of matter that simultaneously displays both superfluidity and crystalline order . much of our understanding of this exotic state is based on the pioneering work of penrose and onsager,@xcite andreev and lifshitz,@xcite chester and reatto,@xcite leggett,@xcite and anderson.@xcite recently , anderson and coworkers revisited this problem . @xcite current developments in this field , presented at a kitp workshop at santa barbara , are available online.@xcite @xmath0he has long been thought to be the most likely candidate for the supersolid state . torsional oscillator experiments by kim and chan @xcite generated renewed interest in this possibility . @xcite in addition to the work of kim and chan , @xcite there is now an independent confirmation of the anomalous behavior of solid @xmath0he , as presented by the groups of reppy and shirahama.@xcite all of these groups use torsional oscillators similar to those employed by kim and chan.@xcite rittner and reppy @xcite report history dependence of the signal , when annealing the sample , to the extent of no observation of any mass decoupling in the torsional oscillator experiment . on the other hand , rapid freezing of helium leads to disorder and a drastic increase of the signal.@xcite taken at face value , these torsional oscillator experiments indicate an anomalous mechanical behavior of solid @xmath0he at low temperatures . nevertheless , the connection between the mechanical measurements and the suggested supersolidity remains tenuous . the case for supersolidity entails a certain assumption , which we will discuss at length below , for the interpretation of the oscillator data . the measurements by refs . monitor the period of torsional oscillators in the presence of an applied torque . the purpose of our work is to examine the mechanical properties of the torsional oscillator . we will only allude to linear response theory and causality ( the kramers - kronig relations ) . we show that the change in torsional oscillator period may be triggered by a change in damping and other oscillator parameters . such a change may result from a low - temperature quench of residual topological defects in the solidification into a glass . here , we will use the term `` liquidlike '' component to describe elastic defects that are not pinned above a glass transition at high temperatures . in ref . , we first explained how a low - temperature pinning of elastic defects ( two - level tunneling systems ) can account for the reported excess low - temperature specific heat with regards to a perfect debye crystal . the results of ref . are at odds with a _ simple _ uniform supersolid transition , but can also occur in an exotic glassy supersolid state as discussed by boninsegni et al . @xcite or wu and phillips@xcite . the effects described in this paper may account for the observed change of the torsional oscillator period . the central thesis of our current work is that there is no imperative to adduce a supersolid fraction which depends very sensitively on a host of external parameters in order to explain the reduction in the torsional oscillator period as temperature is lowered . rather , the observed trends might be a very natural and quite universal outcome of a glass transition ( regardless of its classical or quantum nature ) . a direct proof of superfluidity would be the observation of persistent current . in this regard , we note a recent experimental search for superflow by day et . al.,@xcite who found no mass flow of any kind to very high accuracy . relying on these results and , most notably , on a new thermodynamic analysis , we recently concluded @xcite that the effect first observed @xcite is likely not an intrinsic property of solid @xmath0he . this is so because the low - temperature behavior depends critically on the @xmath1he concentration , shows annealing and rapid freezing dependence , @xcite and , most importantly , has a specific heat which is inconsistent with a simple supersolid transition of a 1% condensate fraction.@xcite however , our earlier work @xcite does not rule out a supersolid fraction of order @xmath2 . our principal findings are briefly summarized in sec . ( [ import ] ) . to set the stage for these results , we will briefly review , in sec . ( [ nc ] ) , the non - classical rotation inertia ( ncri ) effect . we then discuss the current possible ground - breaking implication to the observations of refs . [ wherein the change in torsional oscillator period may be triggered by a supersolid phase ] . we then step back in sec . ( [ how ] ) and analyze the results for a first principle linear response analysis without assuming the ncri . consequently , we show how the experimental results are consistent with a change in damping or other oscillator parameters which are brought about by the solidification of a small liquidlike component as the temperature is lowered . in sec . ( [ sssolid ] ) , we examine the experimental consequences of a uniform supersolid transition and illustrate that a simple supersolid transition can not account for the peak in the dissipation observed by ref . . we then determine , in sec . ( [ glass_section ] ) , the angular response for a glass transition , which can account for all of the existing trends in the data , derive in detail our new results on the dissipation and torsional oscillator period for a glass , and suggest an experiment to distinguish between the glass versus supersolid scenario . we conclude in sec . ( [ conc ] ) with a brief summary of our results and their relevance to the torsional oscillator data of refs . . in the appendix ( sec . [ alts ] ) , we illustrate that other , non - glass , response functions can also account for the data without assuming a supersolid transition . we will address the linear response theory of a driven torsional oscillator and derive our key results in sec . ( [ glass_section ] ) . a general treatment of the problem involves the analysis of possible modes in the vessel which are excited by the external torque and their influence on the torsional oscillator . depending on their character , such modes can easily be disrupted by the insertion of barriers and lead to a far smaller difference between the response of a liquidlike component and that of a glasslike component . to make the discussion clear , we will focus on a simple form for these modes , which are characteristic of glass formers . here we will show : a glass transition , irrespective of whether or not it appears in a normal solid or supersolid , leads to specific testable predictions for the oscillator period and dissipation.@xcite unlike a _ simple _ supersolid transition , i.e. , a transition where only a change in the inertia of the oscillator occurs , our key result eq . ( [ gfinalg ] ) predicts that , as the temperature is lowered , two principal trends will be noted : ( i ) a monotonic decrease in the oscillator period and ( ii ) a peak in the dissipation . a uniform , mean - field type , supersolid transition can not account for phenomenon ( ii ) . it is important to stress , that unlike all of the works to date , we do not assume that only a supersolid can account for the observed decrease in the oscillator period [ feature ( i ) ] . indeed , as we show for the first time , glassy relaxations mandate the current observations of features ( i ) and ( ii ) . this occurs universally and is independent of the specific microscopic mechanism by which relaxation processes occur or the detailed character of the glass . it is nevertheless encouraging to note that samples in which the most pronounced anomalous behavior is observed contain defects.@xcite we considered other ( non - glass ) `` freezing '' transitions that can also account for the empirical trends . to make this concrete , in the appendix a , we will detail how a decrease in damping ( as a result of a freezing transition ) can also account for the observed tendencies . unlike for the results discussed above , here we can not provide a specific functional form to fit to . to provide the simplest qualitative form , we invoke gaussian distributions for the quantities in question . finally , we note that throughout our work , our general form for the angular response allows for a dependence on external parameters such as the initial oscillator velocity . these parameters , e.g. stiffness and density and cell torsional frequency , which parameterize the external torques , are convolved with the intrinsic angular response . a _ liquidlike _ component in the cell may respond differently to different initial oscillator velocities . such a dependence is observed experimentally . aside from other possible effects , external parameters [ whether in a supersolid , a glass , or in any other phase ] will also always appear via their incorporation in the external torques in the general form for the angular response . the basic idea underlying the torsional oscillator measurements is a test of the non - classical rotational inertia ( ncri ) - the inability of a superfluid to rotate under an applied torsional drive . the analog of this experiment on liquid @xmath0he was performed by andronikashvili . @xcite later hess and fairbank @xcite verified the existence of the ncri and of a rotational meissner effect for superfluid helium , which was predicted by london . @xcite as a consequence of a superfluid state , which no longer rotates with the `` normal '' liquid , the effective moment of inertia decreases as the superfluid fraction @xmath3 increases @xmath4 \label{londone}\end{aligned}\ ] ] which is smaller than the `` classical '' moment of intertia @xmath5 of the combined oscillator - helium system . for an ideal torsional oscillator of stiffness @xmath6 , a measure of the period ( @xmath7 ) indicates what the superfluid fraction @xmath3 is . the inferred results for @xmath3 @xcite agree well with the superfluid fraction measured by other probes . the current situation for solid @xmath0he is far from being as clear cut . the experiments show that the rotational motion under an applied torque becomes more rapid at lower temperature- suggesting an analogue of the ncri for a _ supersolid _ phase of helium . in this paper we point out that the measurements are also consistent with less exotic material effects , which can be distinguished by further experiments . the ncri interpretation of the existing data is very simple and suggestive . in what follows , we present a very brief mechanical analysis of the measurements which points to an equally simple explanation . to keep the analysis as general as possible , we rely on first principles alone . the torsional oscillator experiments measure the susceptibility - they do not directly monitor the moment of inertia of the supersolid . we start by writing down the general equations of motion for a torsional oscillator defined by an angular coordinate @xmath8 , @xmath9 \theta(t ) = \nonumber \\ = \tilde{\tau}_{ext}(t ) + \int \tilde{g}(t , t';t ) \theta(t ' ) dt ' . \label{de}\end{aligned}\ ] ] here , @xmath10 is the moment of inertia of the torsional oscillator , @xmath6 is its restoring constant , @xmath11 is the dissipative coefficient of the oscillator , @xmath12 arises from the back action of solid @xmath0he ( it plays the role of a `` polarization '' ) , and @xmath13 is the externally imposed torque . in general , @xmath12 is temperature ( @xmath14 ) dependent . the oscillator angular coordinate @xmath15 is a convolution of the applied external torque @xmath16 and the response function @xmath17 , @xmath18 causality demands that @xmath19 . this implies that @xmath20 ; under a fourier transformation , this leads to the kramers - kronig relations which we will briefly touch on later . as in any time translationally invariant system , the fourier amplitude of the angular response of the torsion oscillator is a product @xmath21 with @xmath22 the angular susceptibility and @xmath13 the external torque in fourier space . for the simple torsional oscillator , @xmath23 . \label{central}\end{aligned}\ ] ] here , @xmath24 is the fourier transform of the real time @xmath12 of eq . ( [ de ] ) . for an ideal normal solid , with a moment of inertia equal to @xmath25 , which rotates with the oscillator , the back action @xmath26 is @xmath27 with @xmath28 the normal component of solid @xmath0he , which varies with temperature and the dissipation @xmath29 is constant . the moment of inertia contribution of the helium is orders of magnitude smaller than that of the empty vessel - the changes observed in the period are very small and are a remarkable experimental triumph . the subscript in @xmath30 refers to the supersolid interpretation of the results - only a fraction of solid helium ( the `` normal part '' ) rotates in unison with the oscillator . ( [ ssberg ] ) is consistent with the ncri form of eq . ( [ londone ] ) . however , we do not need to impose this form on the existing data . current experiments measure the oscillator period @xmath31 with @xmath32 the real part of the solution of @xmath33 at fixed @xmath14 . @xcite for example , a decrease in the dissipative component @xmath29 in the back action @xmath26 with @xmath34 as the temperature is lowered , will also lead to a shorter rotation period . this observation offers a qualitatively different interpretation of the experimental results @xcite with no need to invoke supersolidity . note that _ no _ superfluid phase is needed to explain the data and there is _ no _ ncri effect ; the moment of inertia @xmath25 is temperature independent . the origin of the subscript in eq . ( [ glasse ] ) alludes to a scenario wherein a higher temperature mobile liquidlike component of the sample `` freezes '' at lower temperatures leading to a decrease in the dissipation @xmath35 . in the appendix , we examine in detail the consequences of eq . ( [ glasse ] ) . to make our discussion more lucid , we remark that a qualitatively similar effect appears in the rotation of hard versus soft boiled eggs . the solid hard boiled egg rotates faster than the , liquidlike , soft boiled egg . the measured decrease in the rotation period found @xcite only implies a crossover in @xmath36 ( and a constraint on @xmath37 ) . as the real and imaginary parts of @xmath36 are related by the well known kramers - kronig ( kk ) relations , @xmath38 an enhanced decrease in @xmath39 often appears with a pronounced peak in @xmath40 . a nonvanishing @xmath40 at finite frequency mandates dissipation . we expect the data to indicate an increase in dissipation concurrent with the reduction of torsional oscillator period . whether or not experimental data adhere to the kk relations is a powerful check that needs to be done . in the sections that follow , we explain in some depth how the supersolid and glass pictures can both account for the decrease in the rotational period when the temperature is lowered . we further examine the dissipation . we now determine the experimental consequences of a simple supersolid transition in which the moment of inertia follows eq . ( [ londone ] ) ( the well known ncri effect ) . here , the response is given by eq . ( [ ssberg ] ) . we show that while a mean - field type ncri effect can , as is well known , account for the decrease of the rotation period it can not account for the peak in the dissipation @xmath41 observed by ref . . we start by reviewing results for an underdamped harmonic oscillator . the temperature dependent period of a general damped oscillator of combined effective moment of inertia @xmath42 , @xcite stiffness @xmath6 , and dissipation @xmath35 is @xmath43\}\end{aligned}\ ] ] with @xmath44 a complex amplitude . for an underdamped oscillator , the period @xmath45 and the damping rate of the oscillation amplitude @xmath46 the `` quality factor '' @xmath47 , which monitors the number of oscillations required for a system to have its energy drop by a factor of @xmath48 , is @xmath49 we can rewrite the changes in oscillator period as result of small changes in @xmath50 as @xmath51 . \label{t_expand}\end{aligned}\ ] ] we see from eq . ( [ t_expand ] ) , for damping @xmath52 , that the observed decrease in the rotation period , i.e. , @xmath53 as the temperature is decreased may be explained by either ( 1 ) a purported supersolid transition with @xmath54 , where @xmath55 and @xmath56 ; ( 2 ) a ( non - glass ) freezing transition with a simplified @xmath57 , where @xmath29 becomes smaller as the temperature is decreased , i.e. , @xmath58 and @xmath59 , for more details see the appendix [ alts ] ; ( 3 ) a glass transition with an effective increase in the stiffness constant , where @xmath60 as temperature is lowered . the glass response to be studied later in sec . [ glass_section ] emulates , in part , the features of ( 3 ) . first , we will consider a supersolid in which @xmath54 of eq . ( [ ssberg ] ) , @xmath61 is fixed and @xmath62 varies with temperature . later on , we will comment on the effect of a drop in dissipation expected to accompany the supersolid state . for @xmath54 , we can deduce @xmath62 and then predict the damping rate @xmath63 . in this case , the damping rate @xmath64 or , equivalently , @xmath65 in eqns . ( [ modelb ] , [ qb ] ) , only the period @xmath66 varies with temperature . in this simple supersolid picture , the q factor is monotonic in temperature . if @xmath67 decreases as the temperature is lowered , then the @xmath47 factor will decrease monotonically as the temperature is lowered . a simple supersolid transition is inconsistent with the data @xcite where a pronounced peak in @xmath41 is seen near the transition . a concurrent monotonic drop in the dissipation is expected to accompany the supersolid transition . if the drop in the dissipation @xmath35 is proportional to the drop in the effective moment of inertia then @xmath41 will still be monotonic . here , @xmath41 may increase as @xmath14 is lowered . such an amended simple supersolid picture is still inconsistent with the observed peak of @xmath41 . @xcite obviously , a nonuniform change in both @xmath68 and @xmath62 can be engineered to account for the data . similarly , a broadening of the transition parameters , similar to that discussed in the appendix , can lead to a peak in @xmath41 . we next illustrate how a glass transition can account for the observed data . a glass transition will not only give rise to a decrease in the period but , unlike the supersolid scenario , will also lead to a peak in the dissipation observed by ref . . the external torque is the derivative of the total angular momentum , @xmath69 where @xmath70 is the distance to the axis of rotation , @xmath71 is the mass density and @xmath72 the local angular velocity about the axis of rotation . the experimentally measured quantity is the angular motion of the torsional oscillator - not that of the bulk helium , which is enclosed in it . ab initio , we can not assume that the medium moves as one rigid body . similar to a vessel partially filled with a liquid component , e.g. a soft boiled egg , an initial imparted external torque can lead to a differential rotation between the outer torsional oscillator and a liquid within it . if the liquid freezes " into a glass the medium will move with greater uniformity and speed . this may lead to an effect similar to that of the ncri , although its origin is completely different . furthermore , as a function of initial rotation speed , the variance between the response of hard " glasslike and soft " liquidlike media changes as temperature is lowered . such a difference is indeed observed in the torsional oscillator experiments on @xmath0he . our explanations do not require the supersolid fraction to depend on the rotation speed in order to account for the data . in what follows , we will analyze the effective equation of motion for the torsional oscillator . excited modes within the medium in its liquid phase can lead to additional dissipative torques acting on the torsional oscillator . these modes can become far slower and effectively disappear as the system freezes into a glass state . depending on the character of these modes , the insertion of a barrier may or may not lead to a change in the angular motion of the torsional oscillator . for modes corresponding to internal flows around the axis of rotation , such barriers will disturb the liquidlike modes . such constrictions will lead to a far smaller difference between the period of rotation of the glass and the period of rotation with liquidlike component of @xmath0he , if the modes are local . henceforth , we will focus on conventional forms for glasslike relaxations which might be of use for fitting data . glasses are characterized by universal response functions over a wide range of frequencies and temperatures . we assume that the additional dissipative modes triggered by rotation have a similar form . to be specific , we will assume that @xmath26 obeys the simple dependence as seen in the far better measured dielectric response functions ( where it reflects the polarization ) of glasses . it is given by a dyson - like equation , which has been invoked in eq . ( [ central ] ) , @xmath73^{-1 } , \nonumber \\ \chi^{-1 } & = & \chi_{0}^{-1 } - g_{gl}. \label{dyson}\end{aligned}\ ] ] here , @xmath74 \label{normalres}\end{aligned}\ ] ] is the inverse susceptibility of the underdamped system formed by the torsional oscillator chassis and normal solid , while @xmath75 is the response function of the overdamped glass component . physically , the first term ( @xmath76 ) in eq . ( [ dyson ] ) corresponds to the response of the bare oscillator to an applied torque , the possible excitation ( by the rotating oscillator ) on a transient mode in the liquid / glass medium , which then acts back on the torsional oscillator at a later time ( @xmath77 ) , and all similar higher order processes . employing the standard overdamped form for glass response functions @xcite @xmath78^{-\beta } , \label{cd}\end{aligned}\ ] ] we will be able to provide an explicit form for @xmath79 and thus for all periods and dissipation as a function of temperature . in eq . ( [ cd ] ) , @xmath80 is the characteristic equilibration time of the liquidlike component when it is perturbed . this time @xmath80 diverges in the glass phase ( at temperatures @xmath81 ) and is nearly vanishing at very high temperatures . similarly , @xmath82 is an exponent determining the distribution of local relaxation processes . @xmath83 corresponds to a stretched exponential exponent in real time . for smaller value of @xmath83 , the distribution of local relaxation frequencies about the dominant process at @xmath84 is more smeared out . if @xmath85 , then we will have a single overdamped oscillator of damping time @xmath80- eq . ( [ cd ] ) then corresponds to the response function of an oscillator ( e.g. eq . ( [ normalres ] ) ) with no quadratic - in-@xmath86 ( inertia ) term . the mobile liquidlike component of the sample `` freezes '' at lower temperatures into a solid glass . this , e.g. , can be triggered by the quenching of dislocations or other defects at low temperatures . in ref . , marked superfluid - like behavior was indeed observed only in samples which contained grain boundaries - no superfluid behavior was noted in crystals of high quality . this inverse susceptibility of the glass can be approximated by a stretched set of overdamped oscillators . this is the physical content of davidson - cole form of eq . ( [ cd ] ) . the davidson - cole form @xcite fits the dielectric response data of glasses very well . more sophisticated nearly universal response functions , which may improve on the analysis that we give here , were reported in refs . . in what follows , we will embark on an initial davidson - cole analysis of the @xmath87he data . if we invoke the davidson - cole @xcite form for @xmath75 ( eq . ( [ cd ] ) ) in the sum of all possible intermediate contributions of the glass to the total response of the oscillator , then , from eq . ( [ dyson ] ) , @xmath88 . \label{central_glass}\end{aligned}\ ] ] it is easy to verify , by employing eqns . ( [ periodg ] , [ dampingg ] , [ qfac ] ) , that for very high @xmath14 ( where @xmath80 is small ) eq . ( [ central_glass ] ) predicts a period @xmath89 i_{eff } - ( \gamma + g_{0 } \beta s)^{2 } } } , \label{ti}\end{aligned}\ ] ] and a q - factor @xmath90 similarly , at very low @xmath14 ( where @xmath80 diverges ) , the corresponding quantities are given by eqns . ( [ periodg ] , [ dampingg ] , [ qfac ] ) with no change in the parameters given therein . a comparison of the two limits of high ( @xmath91 ) and low ( @xmath92 ) temperatures reveals that the @xmath47 factor is higher at low @xmath14 while the period @xmath66 is higher at very high temperatures @xmath14 . at intermediate temperatures ( where @xmath80 is of the order of the period of the underdamped oscillator ) , the angle is a superposition of a many modes stretched about @xmath93 . from eqns . ( [ de ] , [ ft ] ) , @xmath94^{-1 } \int dt'~\tau_{ext}(t ' ) \exp[- i \omega ( t - t ' ) ] . \label{gfinalg}\end{aligned}\ ] ] eq . ( [ gfinalg ] ) represents the final form for the angular evolution for all @xmath14 . here , @xmath95 is the value of the external torque at time @xmath96 . for a delta function torque , @xmath97 , the last integral simplifies . within our general formulation , and in eq . ( [ gfinalg ] ) in particular , the observed dependence of the period on the external parameters is perhaps not as surprising as demanding a superfluid fraction strongly depend on the oscillation velocity : for example , different initial velocities would correspond to different values for the internal integral @xmath98 $ ] . this integral would multiply the total susceptibility in all cases [ whether we have a glass transition , a supersolid transition , or any other transitions ] . in a treatment which is more detailed than the one which we outline here , the transient modes and the consequent form of the response function @xmath37 would also depend on external parameters such as initial rotation velocity . we anticipate that when the relaxation time is similar to the period of the underdamped oscillator , the dissipation will be maximal . this will lead to the largest magnitude in the imaginary component in the singularities of @xmath79 . here , the glassy components respond with the same frequency as the `` normal '' component . at both much higher or much lower temperatures , they merely change the net effective spring constant but do not lead to additional modes which closely interfere with the oscillations of the `` normal '' ( non - glass ) part . this leads to a strong decoherence and to a sizable energy loss . we can examine the @xmath99 ( the glass phase ) and the @xmath100 limits and perturbations about them when no dissipation is present- @xmath101 . in these limits , we have ideal harmonic oscillators with no dissipation and consequently @xmath102 . when we expand about the @xmath103 limit and allow for a small @xmath80 , then as seen from eq . ( [ qi ] ) , @xmath41 becomes small but finite ( nonzero ) . similarly , when @xmath104 , where @xmath80 is extremely large but finite , @xmath36 has singularities off the real @xmath86 axis . in eq . ( [ gfinalg ] ) , this small imaginary component now leads to a small dissipation . he at 27 bar . the circles are data from rittner and reppy @xcite and the line is our fit above @xmath105 k for a simple glass model , eqns . ( [ xp ] , [ q-1p ] ) , with the functional form @xmath106^{-1 } + q_\infty^{-1}$ ] . the fit parameters are @xmath107 sec@xmath108 , oscillator frequency @xmath109 hz , asymptotic inverse quality factor @xmath110 , glass relaxation time @xmath111 @xmath112 , and activation barrier @xmath113 k. , width=283 ] he at 27 bar . the circles are data from rittner and reppy @xcite and the line is our simple glass model , eq . ( [ yp ] ) , with the functional form of eq . ( [ taup ] ) , @xmath114^{-1}})^{-1}$ ] . here the _ only _ adjustable parameter is @xmath115 sec@xmath116 , otherwise same parameters as in fig . , width=283 ] . the curves of figs . [ figq ] and [ figp ] are reploted against each other . the skewness of the experimental data ( circles ) compared to the semi - circle line ( theory ) is a well - known consequence of a _ real _ glass exponent @xmath117 [ see eqs.([cd ] , [ central_glass ] ) ] , which for simplicity was set to @xmath118 in our analysis . , width=264 ] this can be made precise for @xmath85 where the poles are determined by the roots of a cubic equation in @xmath86 . here , we can simply look for the largest magnitude of the imaginary part of all of the poles and see when it is maximal as a function of @xmath80 . a larger imaginary part implies a shorter decay time and a smaller value of @xmath41 . the exact expressions are not illuminating . the asymptotic corrections are , however , very transparent . as can be seen from eq . ( [ central_glass ] ) , for an ideal dissipationless oscillator ( @xmath119 ) , @xmath120 is the pole of @xmath121 in the low - temperature limit where @xmath92 . if we expand about this pole , @xmath122 , then we will find that the two dominant poles attain an imaginary component of magnitude @xmath123 this lorentzian peaks , as in fig . [ figq ] , when @xmath124 . at this value of @xmath80 , the poles have a maximal imaginary component and the dissipation is the largest . in the real dissipative oscillator ( with small @xmath125 ) , the inverse @xmath47 value is given by @xmath126 & \nonumber \\ & & \label{q-1p}\end{aligned}\ ] ] with @xmath127 the linear term in @xmath35 ( see , e.g. , eq . ( [ qfac ] ) ) . by contrast , the correction to the absolute values of the real part of the poles is @xmath128 \frac{1}{1 + ( \omega_{0 } s)^{2}}. \label{yp}\end{aligned}\ ] ] the function @xmath129 is a monotonic function of @xmath80 and thus of temperature . the period @xmath130 decreases monotonically when the temperature is lowered , see fig . [ figp ] . the four relations of eqns . ( [ periodg ] , [ qfac ] , [ ti ] , [ qi ] ) along with the four measured values [ the periods at the high and low temperatures , the @xmath47 factors at high and low temperatures ] allow us to determine the four parameters @xmath148 and @xmath37 . in fact , due to the scale invariance of the relations , there are only three unknowns ( e.g. @xmath149 , and @xmath150 ) from which the fourth value can be predicted and compared to its experimental value . currently , the available data centers on the region of the transition and it is not certain what the asymptotic low and high temperature values of the @xmath47 factors ( @xmath151 for @xmath104 , @xmath152 for @xmath153 ) or the periods ( @xmath154 for @xmath104 , @xmath155 for @xmath153 ) are . if we solve for all unknown quantities in terms of @xmath156 , then we have @xmath157^{-1 } \right ) \approx 4 \pi^2 / p_0 , \nonumber \\ \gamma / i_{eff } & = & 4 \pi ( q_{\infty } p_{\infty } ) ^{-1 } ( { 4 - q_{\infty}^{-2 } } ) ^{-1/2 } \approx 2 \pi / ( q_\infty p_\infty ) , \nonumber \\ g / i_{eff } & = & 4 \pi^{2 } ( p_{0}^{-2 } -p_{\infty}^{-2 } ) \approx \alpha \ , ( 1 - p_0 ^ 2/p_\infty^2 ) .\end{aligned}\ ] ] the choice for the numerical value of the effective moment of inertia @xmath67 corresponds to a different choice of units . neither the precise values of the parameters @xmath158 , @xmath141 , and @xmath137 of eq . ( [ vft ] ) , nor of @xmath83 in eq . ( [ gfinalg ] ) , change qualitatively the form of the fits that result from eq . ( [ gfinalg ] ) . all that matters is that at the temperature of the apparent transition @xmath131 , the dominant relaxation time @xmath159 matches with the torsional oscillator period . putting all of the pieces together , eq . ( [ gfinalg ] ) leads to a monotonic decrease of the rotation period as the temperature is lowered . hand in hand with that , the dissipation becomes maximal when @xmath160 is equal to the period of the unperturbed oscillator . a possible testable consequence of this scenario is an experiment in which a torsional oscillator containing solid @xmath0he is set in motion , and finally is abruptly stopped and then let go again . if the sample is first cooled below the glass transition while at rest , then the vessel contains a solid glass and the torsional oscillator will stop perfectly . because all of the material inside the oscillator will stop in unison with the container however , if the oscillator is stopped abruptly and let go at temperatures above the glass transition , then the vessel contains a liquidlike component and the torsional oscillator will wobble due to the motion of the residual liquidlike component . here , the liquidlike component will still move even after the container is stopped . this internal liquidlike motion will lead to a momentum transfer to the outer torsional oscillator once the container is let go . hence , the oscillator will wobble . in conclusion , we report on a simple alternate proposal of the origin of the decrease in the torsional oscillator period in solid helium . @xcite we argue that changes in the oscillation period are triggered by changes in damping and the effective stiffness in the susceptibility and are not due to a supersolid state formation . we point out that the torsional oscillator mechanical properties can be controlled by a number of effects such as damping , stiffness coefficient and moment of inertia changes . the supersolid interpretation , if such a state exists , would lead to changes in moment of inertia . this was the interpretation taken in refs . . on the other hand , low - temperature quenching of residual topological defects in the solidification into a glass can also account for the current observation of a drop in the torsional oscillator period as the temperature is reduced . this effect not only accounts for the decrease in the rotation period ( fig . [ figp ] ) , but also predicts a peak in the dissipation , see fig . [ figq ] , as indeed observed . @xcite furthermore , our alternate glass scenario can account for the observed dependence of the oscillator dynamics on external parameters . we have developed a basic understanding of how a simplified response of a glass can account for the essential physics results of the torsional oscillator experiments . specific heat data further show very strong support for a low - temperature glass phase @xcite and effectively rule out a simple supersolid transition by thermodynamic measurements . based on our analysis , we can make the following specific predictions which conform with the data available to date : * ( 1 ) * at low temperatures all dynamic observables , e.g. , @xmath41 and @xmath66 , will collapse on a single curve as a function of temperature , which is independent of the frequency of the torsional oscillator . this collapse follows from eqs . ( [ dyson ] ) , ( [ normalres ] ) , and ( [ vft ] ) . it reflects the freezing - out of liquidlike degrees of freedom , where the response is controlled by the _ susceptibility @xmath161 . in general , the higher the resonant frequency @xmath32 is , the higher the temperature @xmath131 at which this freeze out will occur : @xmath162 , as can be seen from eq.([vft ] ) , @xmath163 . at temperatures @xmath164 , all of the data collected from oscillators with different resonant frequencies , in which all other parameters are held fixed , should collapse onto a single curve . * ( 2 ) * in all known glasses the exponent @xmath117 [ eq.([cd ] ) ] and the glass temperature @xmath165 k , [ eq . ( [ vft ] ) ] , while in our analysis we assumed for simplicity and to avoid the use of too many adjustable parameters that @xmath118 and @xmath166 k. for more realistic glass models one would need to relax these constraints . indeed , fig.([figqp ] ) vividly illustrates that better fits may be obtained with values of @xmath167 . similarly , all of the available data to date are consistent with values of @xmath168 mk . the more accurate detailed predictions [ albeit with more phenomenological glass parameters ] follow from eqs.([central_glass ] , [ gfinalg ] , [ vft ] ) . we leave this analysis for a separate discussion when more data are available . * ( 3 ) * the blockage of the annulus in the torsional oscillator cell may drastically change the strain field and dynamics inside the cell . such changes of the boundary conditions can inhibit the presence of various elastic modes relative to those which are present in a system with no blockage . for instance , azimuthal elastic modes which may be present in an `` o - type '' cylindrical geometry can not appear in a blocked `` c - type '' cylindrical configuration . more generally , any modification to the boundary conditions , e.g. , oscillator velocity or amplitude , sample surface or roughness , would shift the freezing - out temperature and damping . for instance , large amplitude vibrations may thwart the quench of a liquidlike component into a glass . such an avoidance of the glass transition will , consequently , lessen the low temperature variations in the oscillator dynamics . all of these effects will necessarily lead to different experimental observables without a need for invoking a supersolid fraction which somehow depends very sensitively on all of these parameters . as a matter of principle , our glass picture explains the data even if a glass transition accompanies the transition into a supersolid state . @xcite what we show is that whether or not a tiny supersolid fraction is present- the changes in the dynamics can be naturally ascribed to a glass transition rather than to a non classical rotational inertia ( ncri ) effect . our results demonstrate that a low - temperature glass can very naturally account for the current data . what our analysis suggests is whether or not a very small supersolid fraction is present , what triggers the change in period may ( very naturally ) be a hallmark of the transition into a glassy state . the changes in the torsional oscillator period need not be accounted for by only a non clasical rotational inertia effect . a glass transition ( whether it is classical or quantum is immaterial on this level of our analysis ) may further naturally account for the observed subtle dependence of the effect on external parameters as well as the concurrency of the peak in the damping with the change in oscillator period . it is worth noting that a decrease in the rotational period along with a peak in the dissipation can be triggered by a host of many other related effects - none of which relies on a ncri effect . as an example , in the appendix we detail an alternate model in which the dissipation decreases by the solidification of liquidlike ( topological ) defects into a non - glassy low - temperature phase . similarly , any other effect which leads to a decrease in the oscillator period with decreasing temperature and exhibits a peak in @xmath41 can account for the current data . finally , an experiment in which a torsional oscillator holding @xmath0he is first cooled when it is at rest , then set in motion and abruptly stopped and let go , might allow further comparison with the glass origin that we propose here for the anomalous low temperature dynamics . for a glass transition scenario , we expect ( 1 ) that at temperatures above the glass transition , the liquidlike component will cause the torsional oscillator to wobble . while ( 2 ) the same experiment performed sufficiently below the glass transition temperature , the glass and container will stop in unison without wobbling . this work was partially supported by the center for materials innovation ( cmi ) of washington university , st . louis and by the us dept . of energy at los alamos national laboratory under contract no . de - ac52 - 06na25396 . we are grateful to a. f. andreev , a. j. leggett , m. paalanen , yu . parshin , j. d. reppy , a. s. c. rittner , and g. volovik for useful discussions . here , we show how the seminal qualitative features of the current available data @xcite can be explained by not only a glass transition [ or even by its more restrictive limiting form , which is given by the simple activated dynamics of eqns . ( [ cd ] , [ act ] ) with @xmath85 plotted in figs . [ figq ] and [ figp ] ) , but also by other , more general , `` freezing '' transitions . glasses adhere to specific , nearly universal , response functions and relaxation time forms - e.g. that of eq . ( [ cd ] ) . @xcite we now consider another `` freezing '' scenario of ( topological ) defects in which , for illustrative purposes , only the dissipation varies with temperature . upon cooling , the liquidlike regions in the solid `` freeze '' and lead to a lower average dissipation . in the dissipative response @xmath169 of eq . ( [ glasse ] ) , the dissipation @xmath170 varies with temperature while @xmath171 is fixed . thus , a measured value of the period can be used to compute @xmath68 and then predict the amplitude damping rate @xmath172 and compare it to experiment . here , @xmath173 with @xmath42 now a constant quantity which is independent of the temperature . similarly , the q factor ( determined by @xmath174 ) is @xmath175 if this alone is what occurs then at all temperatures , the dissipation rate @xmath174 and q - factor will be related to the period by eqns . ( [ modela ] , [ qa ] ) parameterized by the two constants @xmath67 and @xmath6 . on the right hand sides of eqns . ( [ modela ] , [ qa ] ) , only the measured oscillator period @xmath174 varies with temperature , as indeed observed.@xcite the @xmath47 factor monotonically increases as the temperature decreases . this is evident from the final form of eq . ( [ qa ] ) or even from the trivial eq . ( [ qfac ] ) . because @xmath35 decreases as the temperature is lowered , an ensuing increase of @xmath47 follows . we will now address the non - monotonic character of the dissipation . this effect is not present in the treatment thus far . the dissipation ( probed by @xmath41 ) was seen @xcite to exhibit a pronounced maximum in nearly the temperature range where the oscillator period shows its most dramatic decrease . now , near transition points ( whether those of a defect freezing or of other origins ) , fluctuations and consequent dissipation are very often large . here , we can not think of only one damped oscillator for either the quenching of defects nor other transition scenario . to make contact with the previous approach , we may divide the system into external torsional oscillators coupled to a multitude of small damped oscillators within the medium . if the medium is homogeneous then the system can be thought of as a single mode oscillator . otherwise , a more careful analysis is required . in general , we will need to diagonalize the @xmath176 matrix @xmath177 $ ] with the elements @xmath178 , @xmath179 and @xmath180 being the parameters appearing in the equations of motion for the angles @xmath181 of different elements of the solid . in the context of defect freezing , we might anticipate some defects to already be frozen ( and lead to a lower value of @xmath35 in those volume elements ) and for other volume elements to have fewer frozen defects and to correspond to a higher value of @xmath35 . this distribution of damping coefficients leads to a solution for @xmath182 which is a superposition of many modes dispersed in frequency . the broader the frequency dispersion- the larger the incoherence- the smaller the value of the @xmath183 and that of the energy . as a result , the @xmath184 value which records the damping of the energy may be much higher near the transition . the width @xmath186 is generally a function of temperature . it is finite within the transition region and tends to zero outside it . far from the transition , we have a single value of @xmath35 [ i.e. , @xmath187 and our former analysis applies . within the transition region @xmath188 can be read off from the period by the use of eq . ( [ periodg ] ) . the angle is now a superposition of all modes . for a delta function torque @xmath189 , @xmath190 \ } , \label{ttg}\end{aligned}\ ] ] @xmath191 the distribution of @xmath35 values , which we anticipate to be approximated by eq . ( [ gg ] ) , and with @xmath192 and @xmath193 given by eqns . ( [ periodg ] , [ dampingg ] ) . to get an intuitive feeling for the damping triggered by the dispersion , we can expand the argument in eq . ( [ ttg ] ) about @xmath188 to obtain the original solution ( that assuming a single mode defined by a unique @xmath188 ) multiplied by the approximate damping factor @xmath194 . \label{gauss}\end{aligned}\ ] ] here , @xmath195 and @xmath196 let us first examine an ideal situation where no damping initially exists ( @xmath197 ) . here , eq . ( [ gauss ] ) is none other than the fourier transform of a gaussian which is another gaussian given by a time dependence , @xmath198 $ ] . this factor leads to an energy dissipation in time that does not appear for a single mode dispersion : the energy is damped by a factor of @xmath199 relative to that of the nondispersive system . dispersion alone can lead to damping . taking dissipation into account leads to a similar gaussian factor of @xmath200\end{aligned}\ ] ] for the amplitude along with an additional small correction to the phase terms @xmath201 . this additional phase factor is negligible ( over a period of the oscillator ) if @xmath202 . the above gaussian approximation is just a heuristic motivation for visualizing how dispersion lowers the average energy . the precise integral is that of eq . ( [ ttg ] ) . if the width @xmath203 peaks at the transition temperature then the dissipation is amplified near the transition temperature while , all along , the oscillator period is monotonic in temperature . to conclude , we illustrated , once again , how the torsional oscillator data can be accounted for without invoking a supersolid transition . e. kim and m. h. w. chan , nature ( london ) * 427 * , 225 ( 2004 ) . e. kim and m. h. w. chan , science * 305 * , 1941 ( 2005 ) . e. kim and m. h. w. chan , j. low temp . * 138 * , 859 ( 2005 ) . e. kim and m. h. w. chan , phys . * 97 * , 115302 ( 2006 ) . this form is what immediately transpires for @xmath121 with poles of constant @xmath204 . when this general form is applied to the standard oscillator , the period is indeed the interval between consecutive local maxima of @xmath182 [ or , equivalently is twice the interval between consecutive zeros of @xmath182 ] . here and throughout , @xmath67 is defined by the equations of motion ; it is determined by the coefficient of @xmath206 in @xmath79 . generally , @xmath42 with @xmath25 the moment of inertia of the normal he solid and @xmath10 the moment of inertia of the torsional oscillator chassis without the inserted helium . in the presence of a supersolid component , @xmath207 , where @xmath208 is the moment of inertia of the entire system . similar definitions apply to the dissipative coefficient in @xmath79 . with @xmath11 the dissipative coefficient of the bare torsional oscillator chassis the additional dissipative contribution resulting from the inserted helium is given by @xmath209 . k. s. cole and r. h. cole , journal of chem . * 9 * , 341 ( 1941 ) . d. w. davidson and r. h. cole , journal of chem . phys . * 18 * , 1417 ( 1950 ) . d. w. davidson and r. h. cole , journal of chem . * 19 * 1484 ( 1951 ) .

a decrease in the rotational period observed in torsional oscillator measurements was recently taken as a possible indication of a putative supersolid state of helium . we reexamine this interpretation and note that the decrease in the rotation period is also consistent with a solidification of a small liquidlike component into a low - temperature glass . such a solidification may occur by a low - temperature quench of topological defects ( e.g. , grain boundaries or dislocations ) which we examined in an earlier work . the low - temperature glass can account for not only a monotonic decrease in the rotation period as the temperature is lowered but also explains the peak in the dissipation occurring near the transition point . unlike the non - classical rotational inertia scenario , which depends on the supersolid fraction , the dependence of the rotational period on external parameters , e.g. , the oscillator velocity , provides an alternate interpretation of the oscillator experiments .

the collaboration between mathematicians working in knot theory and topological graph theory and chemists working in stereochemistry has been very fruitful so far ( @xcite-@xcite ) . the spatial arrangement of a molecule can be modeled by a * spatial graph * @xmath0 , which is the image of an embedding @xmath1 of an abstract graph @xmath2 into @xmath3 up to * ambient isotopies * ; i.e. , bending , stretching and shrinking of @xmath0 without self - intersections is allowed as long as no edge is collapsed . the value of modeling a molecular structure by a spatial graph lies in the fact that topological properties of the spatial graph are inherited by the molecule . for example , topological chirality implies chemical chirality . a spatial graph is ( topologically ) * chiral * if it is not ambient isotopic to its mirror image . it is * achiral * otherwise ; this is equivalent to the existence of an orientation - reversing homeomorphism of @xmath4 that maps the spatial graph onto itself . a molecule with an underlying chiral graph is automatically a chiral molecule . castle , evans and hyde @xcite proved that polyhedral toroidal molecules which contain a nontrivial knot are chiral . a * polyhedral * molecule has an underlying graph which is planar , 3-connected and simple . a graph is * planar * if there exists an embedding of the graph in the sphere @xmath5 ( or equivalently in the plane @xmath6 ) . such an embedding is a * trivial embedding * and its image is a * trivial spatial graph*. a graph is * _ n_-connected * if at least @xmath7 vertices and their incident edges have to be removed to decompose the graph or to reduce it to a single vertex . a graph is * simple * if it has neither multiple edges between a pair of vertices nor loops from a vertex to itself . nontrivial spatial graphs ( as well as their corresponding molecules ) which embed in the standard torus are called * toroidal*. the argument given in @xcite to show the chirality of polyhedral toroidal molecules which contain a nonsplit link depends partly on a theorem of simon @xcite whose conditions unfortunately are not satisfied in @xcite . simon s theorem states that the hopf ladder with at least three rungs is chiral , assuming that sides are taken to sides . the * hopf ladder @xmath8 * is the spatial graph which is obtained from a hopf link by adding @xmath7 pairs of vertices @xmath9 , where the vertices @xmath10 lie on one link component and the vertices @xmath11 lie on the other , and by adding @xmath7 edges called * rungs * @xmath12 , where @xmath13 has endpoints @xmath14 so that the rungs do not introduce any crossings in a diagram of the spatial graph as illustrated for @xmath15 and @xmath16 in fig . [ hopfladders ] . we generalise simon s theorem with the following proposition : [ prop ] the hopf ladder @xmath8 with @xmath7 rungs is @xmath17 this allows us to complete the proof in @xcite using a different method ( minors instead of the euler characteristic ) and to obtain the following result : [ chiral ] + nontrivial simple 3-connected planar graphs which are embedded in the standard torus @xmath18 are chiral . for the proof we rely on the fact that all planar toroidal spatial graphs contain a nontrivial knot or a nonsplit link : [ goal ] + let @xmath2 be an planar graph and @xmath1 be a nontrivial embedding of @xmath2 with image @xmath0 . if @xmath0 is contained in the torus @xmath18 , it contains a subgraph which is a nontrivial knot or a nonsplit link . the first part of this section contains the outline of the proof of theorem [ chiral ] and preparations for it , in particular the generalisation of simon s theorem on the chirality of hopf ladders . the second subsection proves theorem [ chiral ] . the proof of theorem [ chiral ] uses theorem [ goal ] , proposition [ prop ] and the following three statements . [ murasugi ] + torus knots and torus links with at least three crossings are chiral . [ k ] let @xmath19 be the set of all knots and links up to ambient isotopy contained as subgraphs in the spatial graph @xmath0 . if @xmath0 is achiral , every topological chiral element in the set @xmath19 can be deformed into the mirror image of an element in the set @xmath19 . remark [ k ] says that if an achiral spatial graph @xmath0 contains a chiral spatial subgraph @xmath20 , it must also contain the mirror image @xmath21 of @xmath20 . note that @xmath20 and @xmath21 need not be disjoint in general but are allowed to share edges and points . to set the stage for theorem [ kuratowski ] and the proofs in section [ proofs ] , we introduce minors : an abstract graph @xmath22 is a * minor * of @xmath2 if it is obtained from @xmath2 by a sequence of deleting and contracting edges and deleting isolated vertices . similarly , a spatial graph @xmath23 is a minor of a spatial graph @xmath24 if @xmath23 is obtained from @xmath24 by deletion and contraction of edges and deletion of isolated vertices . * contraction * along an edge @xmath25 of a spatial graph @xmath24 means shrinking @xmath25 to a point while keeping the edges which are attached to the endpoints of @xmath25 attached . contraction of an edge is only defined for edges which are not loops . [ kuratowski ] + a graph is planar if and only if it contains neither @xmath26 nor @xmath27 as minors . * outline of the proof of theorem [ chiral ] : * + the idea of the proof is to see that a simple @xmath28-connected planar spatial graph @xmath24 which is nontrivially embedded in @xmath18 contains a chiral subgraph which can not be extended to an achiral spatial graph by adding vertices and edges on the torus without losing its planarity . theorem [ goal ] ensures the existence of nontrivially knotted or nonsplit linked subgraphs of @xmath24 . this allows a proof in two cases : case 1 deals with the case in which @xmath24 contains a nontrivial knot whereas case 2 covers the case in which @xmath24 contains a nonsplit link . the second case has to further distinguish between the possibilities that either the nonsplit link is different from the hopf link ( case 2a ) or the hopf link ( case 2b ) . in case 1 , the knot is chiral by theorem [ murasugi ] . for @xmath24 to be achiral , the mirror image of the knot must also be a subgraph of @xmath24 by remark [ k ] . therefore , we extend any nontrivial torus knot to a spatial graph @xmath20 so that the criterion of remark [ k ] is satisfied . we show in lemma [ l1 ] that @xmath26 is a minor of every @xmath20 which is constructed in such a way . it follows from theorem [ kuratowski ] that @xmath20 is nonplanar . this proves theorem [ chiral ] if @xmath24 contains a nontrivial knot . in case 2a , the same argument as for the knotted case proves the theorem . the only difference is that here @xmath27 ( instead of @xmath26 ) is a minor of the extension @xmath20 as shown in lemma [ l2 ] . in the remaining case 2b , simpleness and 3-connectivity ensure the existence of the hopf ladder with three rungs ( fig . [ hopfladders ] , right ) as shown by @xcite . the hopf ladder with three rungs is chiral as shown in proposition [ prop ] . here lemma [ l3 ] ensures that @xmath27 is a minor of any achiral extension @xmath20 of the hopf ladder with three rungs . the idea of the argument is similar to the one given by castle , evans and hyde @xcite who showed the statement of theorem [ chiral ] in the case that the spatial graph contains a nontrivial knot . but while the argument in @xcite uses the euler characteristic , we detect one of kuratowski s nonplanar minors @xmath27 and @xmath26 in the achiral extensions . there is a gap in the proof in @xcite for the case that the spatial graph contains a nonsplit link : the argument given there depends on the mistaken presumption that simon @xcite proved the chirality of hopf ladders with at least three rungs . unfortunately , simon s proof assumes that rungs go to rungs and sides go to sides , which is not given in general . we fill the gap by showing the chirality of the hopf ladder with at least three rungs in proposition [ prop ] without making simon s extra assumptions . * proposition [ prop ] * + _ the hopf ladder @xmath8 with @xmath7 rungs is @xmath17 _ the hopf link @xmath29 is achiral as unoriented link but chiral if oriented , which can be easily confirmed by calculating the linking number . one or two rungs do not determine an orientation on the link . since there exists a symmetric representation of the hopf ladder with one or two rungs ( fig . [ hopfladders ] , left ) , these hopf ladders are achiral . we prove the chirality of the hopf ladder @xmath8 with @xmath30 rungs by contradiction . recall that a spatial graph is achiral if there exists an orientation - reversing homeomorphism @xmath31 of @xmath3 which maps the spatial graph onto itself . assume there exists an orientation - reversing homeomorphism @xmath31 of @xmath3 with @xmath32 . every homeomorphism @xmath31 maps nontrivially linked subgraphs onto nontrivially linked subgraphs . since the hopf link @xmath29 which consists of the sides of @xmath8 is the only nontrivially linked subgraph of @xmath8 , it follows that @xmath29 is mapped onto itself , i.e. , @xmath33 . since @xmath31 reverses the orientation , we have @xmath34 , where @xmath35 is the mirror image of @xmath29 . the hopf ladder @xmath29 is chiral since more than two rungs @xmath12 with endpoints @xmath36 determine orientations on the sides of the hopf ladder ( fig . [ hopfladders ] , right : @xmath37 , @xmath38 ) by the order of the endpoints of the rungs @xmath39 respectively @xmath40 , therefore implying that @xmath29 is different from @xmath35 . this contradicts the existence of @xmath31 with @xmath41 and it follows that the hopf ladder @xmath8 , with @xmath30 , rungs is chiral . the following three lemmas will be used in the proof of theorem [ chiral ] to show that achiral extensions of knots , chiral links and @xmath16 on the torus fail to be planar . [ l1 ] + _ @xmath26 is a minor of every spatial graph on the torus which contains both knots @xmath42 and @xmath43 for some relatively prime integers @xmath44 and relatively prime integers @xmath45 . _ let @xmath46 be the spatial graph which is constructed by embedding @xmath47 and @xmath48 with minimal number of intersections in the torus and by adding vertices at the intersection points . ( for example , @xmath49 is drawn on the left of fig . [ ersterfall ] and @xmath50 is drawn on the right . ) view the torus as the rectangle @xmath51 \times [ 0,1]$ ] with opposite sides identified . a meridian is given as @xmath52 $ ] and a longitude as @xmath51 \times \{y\}$ ] . without loss of generality , arrange @xmath42 and @xmath43 on the rectangle in such a way that no vertex lies on the boundary of the rectangle and that @xmath43 runs through its corner point . then there exists a path @xmath53 in @xmath54 from the corner point @xmath55 to the corner point @xmath56 of the rectangle which does not intersect the boundary of the rectangle in any other points and which respects the orientations of @xmath42 and @xmath43 ( fat zig - zag in fig . [ ersterfall ] , left ) . the existence of @xmath53 can be seen as follows ( compare fig . [ ersterfall ] for notation ) : if @xmath57 , set @xmath58 . otherwise , there are exactly two segments of @xmath43 in the interior of the rectangle which are connected to the corner point . denote by @xmath59 the segment with endpoints @xmath55 and @xmath60 and denote by @xmath61 the segment with endpoints @xmath62 and @xmath56 . by construction , @xmath60 lies on @xmath630,1 [ \times \{0\}$ ] and @xmath62 on @xmath630,1 [ \times \{1\}$ ] . consider the region @xmath64 of the rectangle which is bounded by the two segments @xmath59 and @xmath61 , @xmath65 $ ] and @xmath66 $ ] ( shaded region in fig . [ ersterfall ] ) . it follows that @xmath67 is either empty or the union of segments @xmath68 , @xmath69 running parallel to @xmath59 and @xmath61 , each having one endpoint in @xmath63(0,1 ) , s_{n}[$ ] and the other in @xmath63s_{1 } , ( 1,0)[$ ] . therefore , @xmath64 is a union of bands @xmath70 which are bounded by consecutive segments @xmath68 and @xmath71 , @xmath72 , and intervals in @xmath65 $ ] and @xmath66 $ ] between the endpoints of @xmath68 and @xmath71 . since @xmath42 is a nontrivial torus knot , @xmath73 for all @xmath72 since @xmath42 follows both the longitude and the meridian of the torus with positive orientation and since @xmath43 follows the longitude with positive and the meridian with negative orientation , @xmath74 does not run parallel to @xmath68 or @xmath71 , and we conclude that there exists a connected component of @xmath74 which connects @xmath68 and @xmath71 . this is true for all @xmath75 , hence a path from @xmath59 to @xmath61 along @xmath54 inside @xmath630,1 [ \times ] 0,1[$ ] is found . note that this path does not intersect the boundary of the rectangle since no vertex of @xmath54 lies on the boundary of the rectangle by assumption . extending the path along @xmath59 towards @xmath55 and along @xmath61 towards @xmath56 , gives the desired path @xmath53 . [ ersterfall ] , left ) . now construct a minor of @xmath54 as follows : delete the edges of @xmath43 which are not part of @xmath53 , and contract the edges of @xmath76 . this gives the spatial graph @xmath77 , which is an embedding of the abstract graph @xmath78 ( compare fig . [ ersterfall2 ] ) . @xmath78 can be described as a cycle @xmath79 on which @xmath80 vertices @xmath81 are placed , together with additional @xmath80 edges @xmath82 which are chords connecting the vertices @xmath83 and @xmath84 , @xmath85 . note that @xmath86 . it is left to show that @xmath26 is a minor of @xmath78 , which itself is a minor of @xmath54 ( fig . [ ersterfall2 ] ) . note that @xmath87 leads to the same graph @xmath78 , allowing us to restrict the argument to graphs @xmath77 with @xmath88 . also , recall that @xmath89 are relatively prime integers and @xmath90 . the argument works inductively . we present the argument in its entirety and add the details of the two single steps ` taking a minor ' and ` inversion plus renaming ' at the end of the proof . set @xmath91 . if @xmath92 , we are done since @xmath93 . for @xmath94 , we construct a proper minor ( i.e. , a minor which is not the graph itself ) of @xmath95 which is of the form @xmath96 with @xmath97 . by interchanging the roles of the cycle @xmath98 from @xmath96 and its chords , another representation @xmath99 of @xmath96 is obtained . this is possible because the chords are not edges of the cycle @xmath98 but form a closed cycle themselves by construction : @xmath78 is the cayley graph of the cyclic group @xmath100 with @xmath80 elements and generator set @xmath101 . since @xmath102 is a generator of @xmath103 and @xmath89 are relatively prime integers , there exists a unique integer @xmath104 for each @xmath105 such that @xmath106 . relabel the vertices of the graph by @xmath107 . in particular , there exists @xmath108 with @xmath109 , and if we set @xmath110 , the relabeled graph is of the form @xmath111 . @xmath112 and @xmath96 satisfy the relations @xmath113 and @xmath114 . we show that we have either @xmath115 or we have @xmath116 and @xmath117 . in the second case we are done , whereas in the first case we have completed the generic induction step : we now consider @xmath118 , which is obtained from @xmath119 by setting @xmath120 . at each step , we reduce the numbers of vertices and edges in the graph , namely @xmath121 and @xmath122 , respectively , when a minor is taken , i.e. , @xmath123 . in particular , since @xmath124 , it follows that @xmath125 and that for all @xmath126 the @xmath127 are odd numbers . we stop as soon as we either reach @xmath128 and the procedure does not give a proper minor , i.e. , @xmath129 , or we have @xmath124 and @xmath130 , in which case @xmath131 . in any case , we reach @xmath132 after finitely many steps : since @xmath93 , we are done . the steps of the iteration can be pictured as follows : @xmath133 ` taking a minor ' : obtaining @xmath96 from @xmath95 ( fig . [ ersterfall2 ] ) : take the subgraph of @xmath95 which consists of @xmath134 and the first @xmath135 chords . this is precisely the number of chords needed such that each chord is intersected by exactly two other chords . we obtain the formula as follows : if @xmath136 , we must do exactly two full turns along chords . only for @xmath136 , the endpoints of the chords from the second round lie exactly in the middle of the points to which the chords from the first round are attached . if the endpoints of the chords from the second round are closer to the endpoints than to the starting points of the chords from the first round , we have to stop traveling along chords just after completing the second round in order to ensure that every chosen chord is intersected by exactly two other chords . if the endpoints of the chords from the second round are closer to the starting points than to the endpoints of the chords from the first round , we have to stop traveling along chords just before finishing the second round . we can in fact determine in which case we are : @xmath137 is the number of chords before finishing the first round . therefore , @xmath138 is the index of the endpoint of the last chord from the first round . if this vertex is closer to @xmath139 than to @xmath140 , we are in the first case , i.e. , @xmath141 . similarly , we are in the second case if @xmath142 . if @xmath143 , we have @xmath136 . hence , in both cases , we have traveled through the first @xmath144 chords @xmath145 . + to obtain @xmath96 from @xmath95 first delete the chords @xmath146 . then contract iteratively all edges of the cycle @xmath134 which have an endpoint that is not an endpoint of a remaining chord . contract the edge in @xmath134 which connects @xmath139 and the endpoint of @xmath147 . the resulting graph has @xmath148 vertices and @xmath149 edges by construction . again , @xmath150 edges form a new cycle @xmath98 , whereas the other edges are chords @xmath82 connecting the vertices @xmath83 and @xmath151 for @xmath152 , where @xmath153 . therefore , the graph is of the form @xmath96 and @xmath124 . ` inversion plus renaming ' : obtaining @xmath154 from @xmath96 ( fig . [ ersterfall2 ] ) : since the chords are not edges of @xmath98 but form a closed cycle , we can change the roles of the chords and the cycle while leaving the unlabeled graph unchanged . this leads to a representation of the graph in terms of @xmath155 and @xmath156 , which are given by @xmath113 and @xmath157 , as explained above . note that @xmath158 since @xmath159 and @xmath160 . to continue the induction we need to show that @xmath161 as well as @xmath162 unless @xmath116 and @xmath117 , in which case we have already obtained the final graph @xmath132 . thus , if @xmath163 , we have @xmath164 , implying @xmath165 , which contradicts the assumption that @xmath166 . on the other hand , if @xmath167 , we have @xmath114 , which is equivalent to @xmath168 for an integer @xmath7 . since @xmath167 by assumption , this implies @xmath169 , and since @xmath124 and @xmath127 is a positive odd integer , this is equivalent to @xmath170with @xmath171 . consequently , @xmath130 and therefore @xmath172 . hence , @xmath26 is a minor of @xmath78 , which in turn is a minor of @xmath54 . the obtained embedding of @xmath26 in the torus is @xmath173 . this completes the proof . [ l2 ] + _ @xmath27 is a minor of every spatial graph on the torus which contains both links @xmath174 and @xmath175 for some relatively prime integers @xmath102 and @xmath176 and some @xmath177 . _ let @xmath102 and @xmath176 be relatively prime integers and let @xmath177 . then @xmath175 contains two different connected components of the form @xmath178 , which we denote by @xmath179 and @xmath180 , respectively . the components @xmath179 and @xmath180 run parallel on the torus . likewise , @xmath174 contains two different connected components denoted by @xmath181 and @xmath182 of the form @xmath42 , which run parallel to each other ( see fig . [ fallzwei ] for notations ) . since @xmath42 follows the longitude and the meridian of the torus with the same orientation and @xmath178 follows the longitude and the meridian with opposite orientation , @xmath181 intersects @xmath179 in at least two points . take one segment @xmath183 of @xmath181 which intersects @xmath179 only in its endpoints denoted by @xmath184 and @xmath185 . if one follows @xmath179 from @xmath184 , the next intersection point denoted by @xmath186 is with @xmath182 . let @xmath187 be the segment of @xmath179 . then there starts a segment @xmath188 of @xmath182 which runs parallel to @xmath183 and intersects @xmath179 only in its endpoints @xmath186 and @xmath189 . let @xmath190 be the segment of @xmath180 which runs from @xmath185 to @xmath189 . this determines a disc in the torus which is bounded by the edges @xmath183 , @xmath190 , @xmath188 , and @xmath187 . since @xmath180 runs parallel to @xmath179 , it cuts the boundary of the disc in exactly two points @xmath191 on @xmath183 and @xmath192 on @xmath188 . following @xmath179 , one passes through the points @xmath184 , @xmath186 , @xmath185 , @xmath189 in this order . this determines the subgraph with the six vertices @xmath193 and the edges @xmath187 , @xmath194 , @xmath190 , @xmath195 , @xmath196 , @xmath197 , @xmath198 , @xmath199 and @xmath200 , which is precisely @xmath27 . being a subgraph , @xmath27 is in particular a minor of every spatial graph on the torus which contains both links @xmath174 and @xmath175 . [ l3 ] + _ @xmath27 is a minor of every achiral spatial graph on the torus which contains the hopf ladder @xmath201 . _ recall that a spatial graph is achiral if and only if there exists an orientation - reversing homeomorphism of @xmath4 which maps the spatial graph to itself . such a homeomorphism induces a graph isomorphism on the graph . graph isomorphisms map cycles to cycles , and graph isomorphisms which are induced by orientation - reversing homeomorphisms invert the sign of the linking number of links and their images . consequently , every achiral graph which contains an oriented link also contains a second link which is its mirror image . the sides of the hopf ladder @xmath201 form an oriented hopf link , without loss of generality realized by @xmath202 , where the orientation is induced by the order of the endpoints of the rungs as described in the proof of proposition [ prop ] . keeping this in mind , we find that there are precisely two options to prevent a graph which contains @xmath201 as a subgraph from inheriting the chirality of the oriented hopf link : firstly , it can contain a second oriented link @xmath203 which is the mirror image of @xmath202 . note that @xmath203 has to be added to @xmath201 since @xmath202 is its only nontrivially linked subgraph . since such an extension contains @xmath204 , it follows from lemma [ l2 ] that @xmath27 is a minor of this extension . or , secondly , the orientation of the hopf link can be eliminated by adding a further rung to the hopf ladder . in that case , we find that the resulting abstract graph is nonplanar , which is independent of the choice of embedding ( fig . [ hopftrafo2 ] ) . an extra edge with vertices @xmath205 and @xmath206 is added whose vertex @xmath205 lies on an edge of one component of the hopf link without loss of generality on the edge with endpoints 1 and 2 , and whose vertex @xmath206 lies in the interior of one of the edges with endpoint 3 on the other component of the hopf link without loss of generality on the edge with vertices @xmath64 and @xmath79 . the hopf ladder @xmath201 with the extra edge @xmath207 contains @xmath27 as a minor as can be seen by deleting the edge between @xmath208 and @xmath28 and contracting the edges between @xmath205 and @xmath208 and between @xmath209 and @xmath28 ( fig . [ hopftrafo2 ] ) . although not every embedding of this extension is an achiral graph , every extension of @xmath201 which does not determine an orientation of the hopf link contains the hopf ladder @xmath201 with an extra edge as constructed above . it follows that every extension of @xmath201 to an achiral graph contains a minor @xmath27 . it is possible to embed the hopf ladder @xmath201 with the extra edge @xmath210 ( as constructed in the proof of lemma [ l3 ] ) as an achiral graph since there is a symmetric representation with the unoriented hopf link mapped onto itself . the resulting spatial graph still lies on the torus but is nonplanar since @xmath27 is a minor ( fig . [ hopftrafo ] ) . it is shown in fig . [ hopftrafo ] how one is led to adding an extra rung when constructing the symmetric representation by extending @xmath201 to an achiral graph which maps the hopf link to its mirror image . we are now ready to prove theorem [ chiral ] . it follows from theorem [ goal ] that the spatial graph @xmath24 contains a subgraph which is a nontrivial knot or a nonsplit link . * case 1 : * the spatial graph @xmath24 contains a nontrivial knot . + a subgraph of a spatial graph on the torus which forms a knot is a torus knot by definition . a nontrivial torus knot can be written as @xmath42 , for some relatively prime integers @xmath102 and @xmath176 with @xmath211 in order to exclude the trivial knot . a nontrivial torus knot is chiral by theorem [ murasugi ] , and its mirror image is @xmath212 . if @xmath24 is achiral , @xmath24 contains both @xmath42 and @xmath178 as subgraphs by remark [ k ] . as shown in lemma [ l1 ] , @xmath26 is a minor of every spatial graph which is embedded in the torus and which contains both knots @xmath42 and @xmath43 for some relatively prime integers @xmath213 and some relatively prime integers @xmath45 . this includes the case of a spatial graph containing both @xmath42 and @xmath178 as subgraphs . the statement of theorem [ chiral ] follows from lemma [ l1 ] since by theorem [ kuratowski ] a graph is nonplanar if and only if it contains neither @xmath26 nor @xmath27 as minors . * case 2 : * the spatial graph @xmath24 contains a nonsplit link . a subgraph of a spatial graph on the torus which forms a nonsplit link is a torus link by definition . a nonsplit torus link with @xmath214 components can be written as @xmath174 for some relatively prime integers @xmath102 and @xmath176 with @xmath177 in order to exclude the unlink . * case 2a : * the spatial graph @xmath24 contains a nonsplit link different from the hopf link . + a nonsplit torus link which is not the hopf link is chiral by theorem [ murasugi ] , and its mirror image is @xmath215 . if @xmath24 is achiral , @xmath24 contains both @xmath174 and @xmath175 as subgraphs by remark [ k ] . as shown in lemma [ l2 ] , @xmath27 is a minor of every graph @xmath24 which is embedded in the torus and which contains both links @xmath174 and @xmath175 , @xmath216 as subgraphs . the statement of theorem [ chiral ] now follows from lemma [ l2 ] and theorem [ kuratowski ] . * case 2b : * the spatial graph @xmath24 contains a hopf link . + in this case 3-connectivity and simpleness imply that the hopf ladder @xmath201 with three rungs is a subgraph of @xmath24 . by proposition [ prop ] , @xmath201 is chiral . if @xmath24 is achiral , @xmath27 is a minor of @xmath24 as shown in lemma [ l3 ] . the statement of theorem [ chiral ] now follows from lemma [ l3 ] and theorem [ kuratowski ] . simpleness and 3-connectivity in theorem [ chiral ] are only needed for the case in which @xmath24 contains no nontrivial knot and the only nontrivially linked subgraph forms a hopf link . if the spatial graph contains a nontrivial knot or a nonsplit link different from the hopf link , these two assumptions can be dropped . it is not possible to weaken the assumptions of theorem [ chiral ] . counterexamples are given or can be constructed as in @xcite . i thank matt rathbun , stephen hyde and the anonymous reviewer for helpful comments and discussions . i thank david rottensteiner for proof - reading and helping me organize the proof of lemma [ l1 ] . the early stage of this research was supported by the roth studentship of imperial college london mathematics department , the daad , and the evangelisches studienwerk .

we investigate properties of spatial graphs on the standard torus . it is known that nontrivial embeddings of planar graphs in the torus contain a nontrivial knot or a nonsplit link due to @xcite,@xcite . building on this and using the chirality of torus knots and links @xcite,@xcite , we prove that nontrivial embeddings of simple 3-connected planar graphs in the standard torus are chiral . for the case that the spatial graph contains a nontrivial knot , the statement was shown by castle _ et al _ @xcite . we give an alternative proof using minors instead of the euler characteristic . to prove the case in which the graph embedding contains a nonsplit link , we show the chirality of hopf ladders with at least three rungs , thus generalising a theorem of simon @xcite .

myotonic dystrophies ( dms ) are autosomal dominant disorders exhibiting a variety of multisystemic features among which muscular dystrophy , myotonia , dilated cardiomyopathy , cardiac conduction defects , cerebral abnormalities , insulin - resistance , and cataracts ; in addition , disease - specific serological abnormalities are present , such as hyperglycemia and increased levels of gamma - glutamyltrans - ferase , hypotestosteronism , and decreased levels of igg and igm immunoglobulin . the more frequent and severe dm form is the dm1-steinert s disease ( omim 160900 ) , which affects 1:8000 individuals worldwide , and is caused by an expanded ( ctg)n nucleotide sequence in the 3 untranslated region of the dystrophia myotonic protein kinase ( dmpk ) gene ( omim 605377 ) on chromosome 19q13 . in 1999 , a second dm form displaying a milder clinical phenotype has been identified : it has been essentially described in european countries and has been called dm2 ( omim 602688 ) ; it is much less frequent than dm1 since it affects 1:20000 individuals , although a recent genotypic study on finnish patients suggested that dm2 frequency could be much higher than previously estimated ; it is caused by the expansion of the tetranucleotidic repeat ( cctg)n in the first intron of the zinc finger protein ( znf-9 ) gene ( omim 116955 ) on chromosome 3q21 . due to its less severe phenotype , diagnosis of dm2 is sometimes difficult and may be made relatively later , compared to dm1 ; to face this difficulty , the localization of ribonucleoprotein ( rnp)-enriched domains ( called foci ) in dm2 cell nuclei has been recently proposed as a rapid and reliable marker for recognizing subjects affected by this pathology . in fact , in tissues of dm2 patients , the expanded - ccug - containing transcripts are retained in the cell nucleus and accumulate in the form of focal aggregates . these nuclear foci of mutant mrna specifically sequester splicing factors among which muscleblind - like ( mbnl ) proteins , which are essential for the alternative splicing for muscle cell proteins , and the rnp - containing complexes called snrnps and hnrnps : this leads to the depletion and/or loss of function of these nuclear regulators . in a recent study , the distribution of nuclear rnp - containing structures and molecular factors responsible for pre - mrna transcription and maturation has been described in myonuclei of dystrophic skeletal muscles , providing evidence for alterations of post - transcriptional pre - mrna events as much as it occurs in the myonuclei of skeletal muscles from old rats . these findings open interesting perspectives for comparative studies aimed at detecting common cellular mechanisms responsible for the loss of muscle mass , strength and function typical of sarcopenia in aged individuals , as well as for the muscle alterations caused by dm2 , which include fibre atrophy - hypertrophy , increased number of centrally located nuclei , and the presence of fibres with nuclear clumps . a common hypothesis proposed to explain skeletal muscle wasting in both sarcopenia and myotonic dystrophy implies a decreased efficiency of muscle regeneration due to hindered activation , proliferation and/or differentiation capability of satellite cells . in vitro myoblast cultures derived from human satellite cells provide a suitable and unique model for studying dm2 muscular precursor cells , and can be used to elucidate the molecular and cellular mechanisms involved in the pathogenesis of this disease . in this work we have investigated some structural and functional features of myoblasts obtained from biceps brachii biopsies in the attempt to detect cell senescence traits in dm2 patients in comparison with healthy control subjects . to do this , satellite - cell - derived myoblasts were grown in vitro , and underwent several passages in culture : for sake of simplicity , myoblasts at early ( 2 and 3 ) passages were defined as young in culture , while those at late ( 14 to 17 ) passages were defined as senescing . we have applied cytochemical and immunocytochemical techniques at light and electron microscopy as proved valuable tools for studying neuromuscular diseases , especially when cell nuclear functions are involved . in fact , in eukaryotic cells , maturation of mrna implies that the primary transcripts ( pre - mrnas ) undergo several transformation steps in the spliceosome , a molecular complex composed of five small nuclear rnps ( snrnps ) , many non - snrnp splicing factors , and regulating factors . the structural counterpart of such macromolecular complexes is represented by rnp - containing structures named perichromatin fibrils , perichromatin granules and interchromatin granules : the correct intranuclear distribution and molecular composition of these structures is essential for mrna maturation , and their ectopic reorganization is a reliable sign of impaired nuclear activity . samples of biceps brachii muscles were taken from male adult patients affected by dm2 ( three subjects , aged 4655 ) as well as from three male healthy donors ( aged 4650 ) , after informed consent . the experimental protocols have been approved by the ethical committee of the irccs policlinico san donato . all the subjects were in the adulthood range , and this allowed excluding the influence of possible aging - related changes in nuclear features . the histological diagnosis was performed on serial sections processed for routine histological or histochemical staining , based on the clinical criteria set by the international consortium for myotonic dystrophies . the biopsies were trimmed of blood vessels , fat and connective tissues , and rinsed in phosphate - buffered saline ( pbs ) ; satellite cells were isolated as reported in cardani et al . and placed in ham s f10 medium ( sigma - aldrich , buchs , switzerland ) supplemented with 15% fetal bovine serum ( gibco , invitrogen , s. giuliano milanese , italy ) , 0.5 mg / ml albumin from bovine serum ( bsa , sigma - aldrich ) , 0.5 mg / ml fetuin , 0.39 g / ml dexamethasone , 10 ng / ml epidermal growth factor , 0.05 mg / ml insulin , 3 mg / ml glucose , 100 u / ml penicillin and 100 g / ml streptomycin ( sigma - aldrich ) . the myoblasts obtained by this procedure were propagated in plastic flasks at 37c in a humidified 95% air / 5% co2 atmosphere . for transmission electron microscopy , myoblasts were grown in flasks , whereas for light microscopy the myoblasts were planted on glass coverslips in multiwell plates ( all the plastics were from euroclone , milan , italy ) . for fluorescence cytochemistry , cells on glass coverslips were fixed with 4% formaldehyde in pbs for 15 min at 4c , post - fixed with 70% ethanol at 20c for 30 min , and rehydrated in pbs at room temperature ( rt ) . to specifically label myoblasts , the slides were incubated for 60 min at rt with a monoclonal antibody recognizing desmin ( dako , glostrup , denmark ) diluted 1:100 in pbs containing 0.1% bsa and 0.05% tween-20 , and then incubated for 60 min at rt with an alexa 488-conjugated anti - mouse igg ( molecular probes , invitrogen ) , washed in pbs , counterstained for dna with hoechst 33258 ( sigma - aldrich ; 1 g / ml for 5 min ) , and mounted in mowiol ( calbiochem , milan , italy ) . 500 desmin - positive cells per patient and passage were scored for brdu - positivity . to estimate the s - phase fraction of myoblasts in the cell cultures , experiments of brdu incorporation were performed . briefly , cells were pulse - labeled with 40 m brdu ( sigma ) for 2 h at 37c , fixed with 70% ethanol for 30 min at 20c , and incubated for 20 min at rt in 2 n hcl , to denature dna partially ; after neutralization with 0.1 m sodium tetraborate ( ph 8.2 ) for 3 min , the slides were washed in pbs , permeabilized for 15 min in pbs containing 0.1% bsa and 0.05% tween-20 , and incubated with the monoclonal antibody recognizing the myoblast - specific desmin , revealed with an alexa 568-conjugated anti - mouse igg ( molecular probes ) , as reported above ; after two washings with pbs , the slides were then incubated for 1 h with an fitc - conjugated anti - brdu mouse monoclonal antibody ( clone b44 ; bd biosciences , beckton dickinson italia , milan , italy ) diluted 1:20 . the slides were finally counterstained for dna with hoechst 33258 ( 0.1 g / ml for 10 min ) , to be finally mounted with mowiol ( calbiochem ) . for fluorescence microscopy , an olympus bx51 microscope equipped with a 100w mercury lamp was used , under the following conditions : 330385 nm excitation filter ( excf ) , 400 nm dichroic mirror ( dm ) , and 420 nm long - pass filter , for hoechst 33258 ; 450480 nm excf , 500 nm dm , and 515550 nm band - pass filter for fitc ; 540 nm excf , 580 nm dm , and 620 nm long - pass filter , for alexa 568 . digital images were recorded with an olympus magnifire digital camera system , and stored on a pc by the olympus software , for processing and printing . the same olympus bx51 microscope previously described was also used for phase contrast microscopy , under the appropriate conditions ; in this case , micrographs were taken with an olympus camedia 5050 digital camera . the percentage of myoblasts containing vacuoles was estimated on 25 randomly selected microscope fields per sample using a 40x objective lens ; at least 500 cells per sample were considered . in order to provide in situ evidence for the presence of senescent myoblasts , -galactosidase was detected according to dimri et al . in brief , samples were washed in pbs and fixed with 2% paraformaldehyde and 0.2% glutaraldehyde in 0.1 m pbs , ph 7.4 , for 7 min at rt . after , cells were incubated for 18 h at 37c in fresh senescence associated sa--gal staining solution [ 1 mg / ml 5-bromo-4-chloro-3-inolyl - b - d - galactoside ( x - gal ) in dimethylformamide ( 20 mg / ml stock ) ; 40 mm citric acid / sodium phosphate , ph 6.0 ; 5 mm potassium ferrocyanide ; 150 mm nacl ; 2 mm mgcl2 ] . after 2 washings in pbs , cells were mounted in a drop of mowiol . myoblasts at early ( 2 3 ) and late ( 14 to 17 ) passages ( as defined after brdu - incorporation experiments , see results ) were fixed in the flasks and then collected by scraping . for conventional morphology , cells were fixed with 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1 m srensen phosphate buffer at 4c for 1 h , washed , post - fixed with 1% oso4 at 4c for 2 h , dehydrated with acetone and embedded in epon . for immunoelectron microscopy , cells were fixed with a mixture of 4% paraformaldehyde and 0.2% glutaraldehyde in 0.1 m srensen phosphate buffer at 4c for 1 h , washed , treated with nh4cl 0.5 m in pbs , dehydrated with ethanol and embedded in lr white resin . ultrathin sections from epon - embedded samples were conventionally stained with uranyl acetate and lead citrate . ultrathin sections from lr white - embedded samples were placed on formvar - carbon coated nickel grids and processed for immunocytochemistry . the sections were treated with the following probes : mouse monoclonal antibodies directed against the phosphorylated , activated form of rna polymerase ii ( research diagnostic inc . , flanders , nj , usa ) or the ( sm)snrnp ( small nuclear rnp ) core protein ( abcam , cambridge , ma , usa ) ; rabbit polyclonal antibodies directed against the cleavage stimulation factors cstf ; chicken antibodies directed against the heterogeneous nuclear rnp ( hnrnp ) core protein . sections were floated for 3 min on normal goat serum ( ngs ) diluted 1:100 in pbs and then incubated for 17 h at 4c with the primary antibodies diluted with pbs containing 0.1% bovine serum albumin ( fluka ) and 0.05% tween 20 . after rinsing , sections were floated on ngs and were then allowed to react for 30 min at rt with the appropriate secondary ( either 6nm- or 12nm - gold - conjugated ) antibodies ( jackson immunoresearch laboratories inc . some grids were incubated without the primary antibody and then processed as described above . to reduce chromatin contrast and selectively reveal nuclear rnp constituents , the sections were bleached by the edta method and observed in a philips morgagni tem operating at 80kv and equipped with a megaview ii camera for digital image acquisition . quantitative assessment of the immunolabelling was carried out by estimating the gold grain density over the nucleoplasmic region on sections treated in the same run . as for anti - snrnp antibody , the grain densities were measured on fifteen randomly selected electron micrographs ( x 22,000 ) of myonuclei from each patient by using a computerized image analysis system ( analysis image processing , soft imaging system gmbh , munster , germany ) . for background evaluation , gold grains present over the selected compartments were counted and the labelling density was expressed as the number of gold grains/m . in addition , the percentage of the nuclear surface occupied by heterochromatin and the perichromatin granules density ( pg number/m of nucleoplasm ) were calculated by using the same image analysis system . statistical comparisons were performed by the two - way anova test to evaluate the influence of two factors : the presence of the dystrophic condition ( we called this factor dystrophy , in tables 1 and 2 ) and the increasing passages in culture ( cell senescing in vitro , in tables 1 and 2 ) ; in addition , the interaction term between these two factors was also considered . the one - way anova test was used to compare the immunolabelling density on interchromatin granules between myoblasts samples from dystrophic or healthy patients at early and late passage . table 1two - way anova test of the morphometric evaluation of heterochromatin percentage and perichromatin granule density ( pg number/m of nucleoplasm ) in myoblasts : factor dystrophy ( healthy and dm2 ) , factor cell senescing in vitro ( early and late passage ) , and interaction term ( dystrophy - cell senescing in vitro).heterochromatin % dystrophyp<0.001cell senescing in vitrop=0.031interaction termp=0.042pg densitydystrophyp=0.063cell senescing in vitrop=0.001interaction termp=0.001 table 2two - way anova test of the immunolabelling densities ( gold grains/m ) of polymerase ii , snrnps , hnrnps and cstf in myoblast nucleoplasm : factor dystrophy ( healthy and dm2 ) , factor cell senescing in vitro ( early and late passage ) , and interaction term ( dystrophy - cell senescing in vitro).polymerase iidystrophyp<0.001cell senescing in vitrop<0.001interaction termp=0.001hnrnpsdystrophyp<0.001cell senescing in vitrop=0.002interaction termp<0.043snrnpsdystrophyp<0.001cell senescing in vitrop<0.001interaction termp<0.001cstfdystrophyp<0.001cell senescing in vitrop=0.027interaction termp=0.017 samples of biceps brachii muscles were taken from male adult patients affected by dm2 ( three subjects , aged 4655 ) as well as from three male healthy donors ( aged 4650 ) , after informed consent . the experimental protocols have been approved by the ethical committee of the irccs policlinico san donato . all the subjects were in the adulthood range , and this allowed excluding the influence of possible aging - related changes in nuclear features . the histological diagnosis was performed on serial sections processed for routine histological or histochemical staining , based on the clinical criteria set by the international consortium for myotonic dystrophies . the biopsies were trimmed of blood vessels , fat and connective tissues , and rinsed in phosphate - buffered saline ( pbs ) ; satellite cells were isolated as reported in cardani et al . and placed in ham s f10 medium ( sigma - aldrich , buchs , switzerland ) supplemented with 15% fetal bovine serum ( gibco , invitrogen , s. giuliano milanese , italy ) , 0.5 mg / ml albumin from bovine serum ( bsa , sigma - aldrich ) , 0.5 mg / ml fetuin , 0.39 g / ml dexamethasone , 10 ng / ml epidermal growth factor , 0.05 mg / ml insulin , 3 mg / ml glucose , 100 u / ml penicillin and 100 g / ml streptomycin ( sigma - aldrich ) . the myoblasts obtained by this procedure were propagated in plastic flasks at 37c in a humidified 95% air / 5% co2 atmosphere . for transmission electron microscopy , myoblasts were grown in flasks , whereas for light microscopy the myoblasts were planted on glass coverslips in multiwell plates ( all the plastics were from euroclone , milan , italy ) . for fluorescence cytochemistry , cells on glass coverslips were fixed with 4% formaldehyde in pbs for 15 min at 4c , post - fixed with 70% ethanol at 20c for 30 min , and rehydrated in pbs at room temperature ( rt ) . to specifically label myoblasts , the slides were incubated for 60 min at rt with a monoclonal antibody recognizing desmin ( dako , glostrup , denmark ) diluted 1:100 in pbs containing 0.1% bsa and 0.05% tween-20 , and then incubated for 60 min at rt with an alexa 488-conjugated anti - mouse igg ( molecular probes , invitrogen ) , washed in pbs , counterstained for dna with hoechst 33258 ( sigma - aldrich ; 1 g / ml for 5 min ) , and mounted in mowiol ( calbiochem , milan , italy ) . 500 desmin - positive cells per patient and passage were scored for brdu - positivity . to estimate the s - phase fraction of myoblasts in the cell cultures , experiments of brdu incorporation were performed . briefly , cells were pulse - labeled with 40 m brdu ( sigma ) for 2 h at 37c , fixed with 70% ethanol for 30 min at 20c , and incubated for 20 min at rt in 2 n hcl , to denature dna partially ; after neutralization with 0.1 m sodium tetraborate ( ph 8.2 ) for 3 min , the slides were washed in pbs , permeabilized for 15 min in pbs containing 0.1% bsa and 0.05% tween-20 , and incubated with the monoclonal antibody recognizing the myoblast - specific desmin , revealed with an alexa 568-conjugated anti - mouse igg ( molecular probes ) , as reported above ; after two washings with pbs , the slides were then incubated for 1 h with an fitc - conjugated anti - brdu mouse monoclonal antibody ( clone b44 ; bd biosciences , beckton dickinson italia , milan , italy ) diluted 1:20 . the slides were finally counterstained for dna with hoechst 33258 ( 0.1 g / ml for 10 min ) , to be finally mounted with mowiol ( calbiochem ) . for fluorescence microscopy , an olympus bx51 microscope equipped with a 100w mercury lamp was used , under the following conditions : 330385 nm excitation filter ( excf ) , 400 nm dichroic mirror ( dm ) , and 420 nm long - pass filter , for hoechst 33258 ; 450480 nm excf , 500 nm dm , and 515550 nm band - pass filter for fitc ; 540 nm excf , 580 nm dm , and 620 nm long - pass filter , for alexa 568 . digital images were recorded with an olympus magnifire digital camera system , and stored on a pc by the olympus software , for processing and printing . the same olympus bx51 microscope previously described was also used for phase contrast microscopy , under the appropriate conditions ; in this case , micrographs were taken with an olympus camedia 5050 digital camera . the percentage of myoblasts containing vacuoles was estimated on 25 randomly selected microscope fields per sample using a 40x objective lens ; at least 500 cells per sample were considered . in order to provide in situ evidence for the presence of senescent myoblasts , -galactosidase was detected according to dimri et al . in brief , samples were washed in pbs and fixed with 2% paraformaldehyde and 0.2% glutaraldehyde in 0.1 m pbs , ph 7.4 , for 7 min at rt . after , cells were incubated for 18 h at 37c in fresh senescence associated sa--gal staining solution [ 1 mg / ml 5-bromo-4-chloro-3-inolyl - b - d - galactoside ( x - gal ) in dimethylformamide ( 20 mg / ml stock ) ; 40 mm citric acid / sodium phosphate , ph 6.0 ; 5 mm potassium ferrocyanide ; 150 mm nacl ; 2 mm mgcl2 ] . after 2 washings in pbs , cells were mounted in a drop of mowiol . myoblasts at early ( 2 3 ) and late ( 14 to 17 ) passages ( as defined after brdu - incorporation experiments , see results ) were fixed in the flasks and then collected by scraping . for conventional morphology , cells were fixed with 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1 m srensen phosphate buffer at 4c for 1 h , washed , post - fixed with 1% oso4 at 4c for 2 h , dehydrated with acetone and embedded in epon . for immunoelectron microscopy , cells were fixed with a mixture of 4% paraformaldehyde and 0.2% glutaraldehyde in 0.1 m srensen phosphate buffer at 4c for 1 h , washed , treated with nh4cl 0.5 m in pbs , dehydrated with ethanol and embedded in lr white resin . ultrathin sections from epon - embedded samples were conventionally stained with uranyl acetate and lead citrate . ultrathin sections from lr white - embedded samples were placed on formvar - carbon coated nickel grids and processed for immunocytochemistry . the sections were treated with the following probes : mouse monoclonal antibodies directed against the phosphorylated , activated form of rna polymerase ii ( research diagnostic inc . , flanders , nj , usa ) or the ( sm)snrnp ( small nuclear rnp ) core protein ( abcam , cambridge , ma , usa ) ; rabbit polyclonal antibodies directed against the cleavage stimulation factors cstf ; chicken antibodies directed against the heterogeneous nuclear rnp ( hnrnp ) core protein . sections were floated for 3 min on normal goat serum ( ngs ) diluted 1:100 in pbs and then incubated for 17 h at 4c with the primary antibodies diluted with pbs containing 0.1% bovine serum albumin ( fluka ) and 0.05% tween 20 . after rinsing , sections were floated on ngs and were then allowed to react for 30 min at rt with the appropriate secondary ( either 6nm- or 12nm - gold - conjugated ) antibodies ( jackson immunoresearch laboratories inc . , some grids were incubated without the primary antibody and then processed as described above . to reduce chromatin contrast and selectively reveal nuclear rnp constituents , the sections were bleached by the edta method and observed in a philips morgagni tem operating at 80kv and equipped with a megaview ii camera for digital image acquisition . quantitative assessment of the immunolabelling was carried out by estimating the gold grain density over the nucleoplasmic region on sections treated in the same run . as for anti - snrnp antibody , the grain densities were measured on fifteen randomly selected electron micrographs ( x 22,000 ) of myonuclei from each patient by using a computerized image analysis system ( analysis image processing , soft imaging system gmbh , munster , germany ) . for background evaluation , samples treated in the absence of primary antibody were considered . gold grains present over the selected compartments were counted and the labelling density was expressed as the number of gold grains/m . in addition , the percentage of the nuclear surface occupied by heterochromatin and the perichromatin granules density ( pg number/m of nucleoplasm ) were calculated by using the same image analysis system . statistical comparisons were performed by the two - way anova test to evaluate the influence of two factors : the presence of the dystrophic condition ( we called this factor dystrophy , in tables 1 and 2 ) and the increasing passages in culture ( cell senescing in vitro , in tables 1 and 2 ) ; in addition , the interaction term between these two factors was also considered . the one - way anova test was used to compare the immunolabelling density on interchromatin granules between myoblasts samples from dystrophic or healthy patients at early and late passage . table 1two - way anova test of the morphometric evaluation of heterochromatin percentage and perichromatin granule density ( pg number/m of nucleoplasm ) in myoblasts : factor dystrophy ( healthy and dm2 ) , factor cell senescing in vitro ( early and late passage ) , and interaction term ( dystrophy - cell senescing in vitro).heterochromatin % dystrophyp<0.001cell senescing in vitrop=0.031interaction termp=0.042pg densitydystrophyp=0.063cell senescing in vitrop=0.001interaction termp=0.001 table 2two - way anova test of the immunolabelling densities ( gold grains/m ) of polymerase ii , snrnps , hnrnps and cstf in myoblast nucleoplasm : factor dystrophy ( healthy and dm2 ) , factor cell senescing in vitro ( early and late passage ) , and interaction term ( dystrophy - cell senescing in vitro).polymerase iidystrophyp<0.001cell senescing in vitrop<0.001interaction termp=0.001hnrnpsdystrophyp<0.001cell senescing in vitrop=0.002interaction termp<0.043snrnpsdystrophyp<0.001cell senescing in vitrop<0.001interaction termp<0.001cstfdystrophyp<0.001cell senescing in vitrop=0.027interaction termp=0.017 in primary culture from skeletal muscles , a fraction of fibroblasts is always present and myoblasts can be recognized by their immunopositivity for the muscle specific protein , desmin ( figure 1a , a ) . in the cultures used in the present investigation , the myogenic index was always fairly high and ranged from about 60% at the 23 passage to more than 90% at the 1417 passage , without significant difference between control and dm2 cell populations . at low ( 2 3 ) passages from the explant , desmin - positive myoblasts had an s - phase fraction ranging from 2026% in both control and dm2 cultures , as estimated after brdu - incorporation experiments . myoblasts were considered as senescing at late ( 14 to 17 ) passages when the percentage of brdu - positive , s - phase cells dropped to less than 5% and 2% , in control and dm2 myoblasts respectively . this suggests that the decrease in the s - phase fraction is faster in dm2 than in control myoblasts . consistently , the percentage of beta - galactosidase positive cells was higher , with a much stronger intensity of the final reaction products , in senescing dm2 than in healthy myoblasts ( about 90 and 80% of positive cells , respectively ) . figure 1phase contrast and fluorescence micrographs of myoblasts from healthy ( a , a and b , b ) and dm2 patients ( c , c and d , d ) at early ( a and c ) and late ( b and d ) passages in culture , after immunolabeling for desmin . in a , the myoblast ( arrow ) may be distinguished from the fibroblast for its thin and elongated shape , and the immunopositivity for desmin ( green fluorescence ) . note the cytoplasmic vacuoles ( arrowheads ) in dm2 myoblasts ( c , d ) . phase contrast and fluorescence micrographs of myoblasts from healthy ( a , a and b , b ) and dm2 patients ( c , c and d , d ) at early ( a and c ) and late ( b and d ) passages in culture , after immunolabeling for desmin . in a , the myoblast ( arrow ) may be distinguished from the fibroblast for its thin and elongated shape , and the immunopositivity for desmin ( green fluorescence ) . note the cytoplasmic vacuoles ( arrowheads ) in dm2 myoblasts ( c , d ) . , myoblasts from both control and dm2 patients appeared as thin elongated cells with a centrally located nucleus . phase contrast microscopy showed that about 15% of young dm2 myoblasts exhibited small roundish vesicles in their cytoplasm ( figure 1c ) , which were on the contrary rarely found in the controls ( less than 4% ) ( figure 1a ) . at late passages , vacuolization of senescing dm2 myoblasts became much more apparent ( about 30% of myoblasts contained vacuoles ) , with large portions of the cytoplasm often occupied by huge vacuoles and devoid of desmin ( figure 1d ) ; about 10% of the myoblasts in senescing controls ( figure 1b ) also showed small vacuoles in the cytoplasm , although there was never evidence of the extensive cytoplasm degeneration found in senescing dm2 myoblasts . at electron microscopy , myoblasts were identified by their elongated shape and the organelle features already described in literature . in the cytoplasm of young control myoblasts ( figure 2 a c ) , ovoid or elongated mitochondria , large amounts of free ribosomes , well developed rough endoplasmic reticulum and numerous golgi complexes were observed ; conversely , lysosomes , residual bodies and vacuoles were only seldom found . myoblast nuclei were generally characterised by a thin heterochromatin rim just beneath the nuclear envelope and one reticular nucleolus with many fibrillar centres and abundant dense fibrillar component ( the latter component is the site of pre - rrna transcription and splicing ) ( for a recent review on nucleolar components , see ) . f ) were even more elongated than at early passages . in the cytoplasm , the organelles belonging to the proteosynthetic apparatus and the mitochondria were abundantly present ; in addition , glycogen clusters , residual bodies and vacuoles - even of large size - were frequently observed . myoblast nuclei showed increased heterochromatin amounts along the nuclear border , while the nucleoli appeared unchanged in comparison to early passages . c ) were quite similar to the controls , apart from the occurrence of differently sized vacuoles in the cytoplasm , and larger amounts of heterochromatin and higher density of perichromatin granules in the nucleus ( figure 4 and table 1 , for the statistical analysis ) . figure 2young ( a c ) and senescing ( d f ) healthy control myoblasts . ( a ) the myoblast shows an elongated shape and one ovoid nucleus with a reticular nucleolus ( nu ) and scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) and a golgi complex ( g ) are visible . ( b , c ) cytoplasmic details showing free ribosomes ( asterisk ) , well developed rough endoplasmic reticulum ( arrows ) , numerous golgi complexes ( g ) and ovoid mitochondria ( m ) . ( d ) the myoblast shows a very elongated shape and one elongated nucleus with scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) , ( e , f ) cytoplasmic details showing free ribosomes ( asterisk ) , ovoid mitochondria ( m ) , a golgi complex ( g ) , a residual body ( r ) and clustered glycogen granules ( star ) . young ( a c ) and senescing ( d f ) healthy control myoblasts . ( a ) the myoblast shows an elongated shape and one ovoid nucleus with a reticular nucleolus ( nu ) and scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) and a golgi complex ( g ) are visible . ( b , c ) cytoplasmic details showing free ribosomes ( asterisk ) , well developed rough endoplasmic reticulum ( arrows ) , numerous golgi complexes ( g ) and ovoid mitochondria ( m ) . ( d ) the myoblast shows a very elongated shape and one elongated nucleus with scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) , ( e , f ) cytoplasmic details showing free ribosomes ( asterisk ) , ovoid mitochondria ( m ) , a golgi complex ( g ) , a residual body ( r ) and clustered glycogen granules ( star ) . scale bars : 1 m . figure 3young ( a c ) and senescing ( d f ) dm2 myoblasts . ( a ) the myoblast shows an elongated shape and one ovoid nucleus with a reticular nucleolus ( nu ) and scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) , a golgi complex ( g ) and many vacuoles ( v ) are visible . ( b , c ) cytoplasmic details showing well developed rough endoplasmic reticulum ( arrows ) , golgi complexes ( g ) , free ribosomes , elongated mitochondria ( m ) , and many vacuoles with heterogeneous content ( v ) . scale bars : 1 m . ( d ) the myoblast shows a very elongated shape and one irregularly shaped nucleus with evident heterochromatin . in the cytoplasm , well developed golgi complexes ( g ) , and vacuoles ( v ) are visible . ( e ) large cytoplasmic regions are filled with heterogeneous vacuoles ( v ) or appear as electron lucent areas ( stars ) . ( f ) cytoplasmic detail showing rough endoplasmic reticulum ( arrow ) , golgi complexes ( g ) , glycogen clusters ( star ) and numerous vacuoles ( v ) . young ( a c ) and senescing ( d f ) dm2 myoblasts . ( a ) the myoblast shows an elongated shape and one ovoid nucleus with a reticular nucleolus ( nu ) and scarce heterochromatin . in the cytoplasm , rough endoplasmic reticulum ( arrows ) , ( b , c ) cytoplasmic details showing well developed rough endoplasmic reticulum ( arrows ) , golgi complexes ( g ) , free ribosomes , elongated mitochondria ( m ) , and many vacuoles with heterogeneous content ( v ) . ( d ) the myoblast shows a very elongated shape and one irregularly shaped nucleus with evident heterochromatin . in the cytoplasm , well developed golgi complexes ( g ) , and vacuoles ( v ) are visible . ( e ) large cytoplasmic regions are filled with heterogeneous vacuoles ( v ) or appear as electron lucent areas ( stars ) . ( f ) cytoplasmic detail showing rough endoplasmic reticulum ( arrow ) , golgi complexes ( g ) , glycogen clusters ( star ) and numerous vacuoles ( v ) . figure 4mean se values of heterochromatin percentage and perichromatin granule density ( pg number/m of nucleoplasm ) in myoblasts from healthy and dm2 patients ( n=45 ) . mean se values of heterochromatin percentage and perichromatin granule density ( pg number/m of nucleoplasm ) in myoblasts from healthy and dm2 patients ( n=45 ) . f ) had very elongated shapes and one elongated nucleus with an often irregular border . in the cytoplasm many vacuoles and large electron lucent areas were abundantly present ; mitochondria , free ribosomes , rough endoplasmic reticulum and golgi complexes were markedly reduced in comparison to the early passages , while glycogen clusters and residual bodies were abundant and ubiquitously distributed . myoblast nuclei frequently showed irregular shapes and evident heterochromatin clumps , and most of the nucleoli showed a reticular structure . observation of edta - stained samples showed that , in all patients , the usual rnp structural constituents involved in pre - mrna transcription and processing were evident in the nucleoplasm : perichromatin fibrils and perichromatin granules were mostly distributed in the perichromatin region , and interchromatin granules formed clusters in the interchromatin space . immunolabelling experiments showed a similar intranuclear distribution of polymerase ii , hnrnps , snrnps and cleavage factor cstf in control and dm2 myoblasts at both early and late passages . activated polymerase ii , hnrnps and cstf were specifically associated with perichromatin fibrils ( figures 5 and 6 ) , which represent the form in situ of pre - mrna transcription , splicing and 3-end processing , while snrnps were restricted to perichromatin fibrils and interchromatin granules , which represent the storage , assembly and phosphorylation sites for transcription and splicing factors ( figure 6 ) . figure 5myoblasts from healthy ( a , b ) and dm2 ( c , d ) patients at early ( a , c ) and late ( b , d ) passages . anti - polymerase ii ( 6 nm ) and anti - cstf ( 12 nm ) antibodies : both probes specifically label perichromatin fibrils ( arrowheads ) , while the interchromatin granules ( ig ) are devoid of signal . myoblasts from healthy ( a , b ) and dm2 ( c , d ) patients at early ( a , c ) and late ( b , d ) passages . anti - polymerase ii ( 6 nm ) and anti - cstf ( 12 nm ) antibodies : both probes specifically label perichromatin fibrils ( arrowheads ) , while the interchromatin granules ( ig ) are devoid of signal . figure 6myoblasts from healthy ( a , b ) and dm2 ( c , d ) patients at early ( a , c ) and late ( b , d ) passages . anti - snrnp ( 6 nm ) and anti - hnrnp ( 12 nm ) antibodies : both probes label perichromatin fibrils ( arrowheads ) ; in addition , the anti - snrnp antibody strongly labels interchromatin granules ( ig ) . myoblasts from healthy ( a , b ) and dm2 ( c , d ) patients at early ( a , c ) and late ( b , d ) passages . anti - snrnp ( 6 nm ) and anti - hnrnp ( 12 nm ) antibodies : both probes label perichromatin fibrils ( arrowheads ) ; in addition , the anti - snrnp antibody strongly labels interchromatin granules ( ig ) . scale bars : 0.25 m . quantitative evaluation of the immunolabelling ( figure 7 ) revealed that both factors , dystrophy and cell senescing in vitro , significantly influence the labelling values for all the parameters analysed ; moreover , the interaction term was always significant indicating a relationship between the changes during in vitro senescence and the healthy or diseased origin of the cells ; in fact , dm2 was always associated with lower levels for all the parameters analysed ( table 2 ) . anti - snrnp labelling density on interchromatin granule clusters was significantly higher in young than in senescing control myoblasts ( 120.5310.04 vs 48.493.01 gold grains/m , respectively ; p<0.001 ) ; conversely , in dm2 myoblasts the values were similar at early and late passages ( 67.867.98 vs 69.596.92 gold grains/m , respectively ; p=0.889 ) . figure 7quantitative immunoelectron microscopy of myoblast nuclei from healthy and dm2 patients ( n=45 ) . each bar represents the mean se values of the labelling density ( gold grains/m ) for different pre - mrna processing factors in the nucleoplasmic region . each bar represents the mean se values of the labelling density ( gold grains/m ) for different pre - mrna processing factors in the nucleoplasmic region . the multifactorial phenotype of dm2 , consisting of muscle weakness and atrophy , and the wide spectrum of extramuscular manifestations strongly support the hypothesis of a multisystemic syndrome caused by a general alteration of the pre - mrna post - transcriptional pathway . however , the cellular mechanisms leading to the highly variable clinical manifestations in the different tissues of dm2 patients have not been clarified yet . in particular , at the skeletal muscle level , no explanation for the muscle wasting has so far been found . it has been hypothesised that , in dystrophic muscle tissue , the myogenic potential is altered , probably in relation to a hindered regenerative capability of satellite cells . interestingly , a similar hypothesis has been also proposed to explain sarcopenia , i.e. the age - related loss of muscle mass and function ; in addition , recent data on dystrophic skeletal muscle myonuclei have demonstrated alterations of mrna pathways reminiscent of those observed during aging . consistent with this hypothesis , the morpho - functional features of myoblasts from healthy and dm2 patients at different passages in culture provided experimental evidence for the more pronounced occurrence of senescence - related events in satellite cells of dm2-affected muscles . at early culture passages , when cell proliferation rate is high , both control and dm2 myoblasts show the typical morphological features of growing myoblasts previously described by several authors , i.e. cells characterised by elongated shapes , cytoplasm rich in free ribosomes , rough endoplasmic reticulum and golgi complexes , nuclei with scarce heterochromatin and prominent nucleoli . at this culture stage , the only distinctive morphological feature of dm2 myoblasts is the presence of several vacuoles in the cytoplasm which could be related to a dysregulation of the protein degradation systems in these cells . therefore , cytoplasmic and nuclear features clearly indicate a high proteosynthetic rate in both control and dm2 myoblasts at early compared to late passages ; in particular , the large amount of euchromatin and the presence of reticular nucleoli with a large dense fibrillar component and numerous fibrillar centres are suggestive of a high metabolic activity . however , the ultrastructural immunocytochemical analyses revealed that dm2 myoblasts are relatively less active than the controls : the immunolabeling for activated polymerase i ( which is necessary to synthesize pre - mrna ) , for hnrnps and snrnps ( which are essential for pre - mrna co - transcriptional splicing ) , and for cstf ( involved in the maturation of 3 ends ) , were all significantly lower in dm2 than in control myoblasts . accordingly , morphometrical evaluations demonstrated an increase in the amount of heterochromatin in dm2 myoblasts , consistent with the already described reduction in protein synthesis . a similar decrease in the factors involved in pre - mrna transcription and maturation , and a parallel increase in the amount of heterochromatin have been found in senescing control myoblasts , when the proliferation rate decreased . however , no significant change in perichromatin granule density has been found in senescing control myoblasts : these granules represent storage and/or transport sites for spliced ( pre-)mrna and their steady number indicates unperturbed rna pathways . moreover , these control myoblasts are characterised by the presence of residual bodies , many vacuoles and glycogen clusters : these are typical features of aging cells , where the cytoplasmic degradation systems undergo dysfunction . thus , dm2 myoblasts at early culture passages ( when they proliferate at a similar rate as the controls ) already show some morphological and functional features found in healthy myoblasts at late culture passage only . the cytoplasmic and nuclear features typical of cells senescing in culture are definitely more pronounced in dm2 myoblasts at late culture passage than in the corresponding healthy controls . the amount of vacuoles and residual bodies is remarkably high , and large cytoplasmic regions appear as empty , likely due to degradation phenomena ; the cell nuclei are often irregular in shape and contain many heterochromatin clumps ; the factors involved in pre - mrna transcription and processing are further reduced in comparison to senescing healthy myoblasts . it should be also noted that snrnps , usually occurring on perichromatin fibrils and interchromatin granules , show an accumulation in the interchromatin granules which has not been observed in senescing healthy myoblasts . intranuclear accumulation of factors involved in pre - mrna maturation has been previously observed in different aging tissues including skeletal muscle , and this has been considered as a consequence of altered pre - mrna processing and/or impaired intranuclear or nucleus - to - cytoplasm transport . accordingly , in senescing dm2 myoblasts a significant increase in perichromatin granule amount has been found ; this phenomenon is known to occur when rna processing is physiologically or experimentally impaired as well as during aging . taken together , the results of the present study demonstrate that satellite cell - derived dm2 myoblasts are characterised by senescence - related features mainly consisting in the early appearance of cytological alterations and impairment of the pre - mrna maturation pathways . it is possible that the sequestration of splicing factors in the foci of dm2 myoblasts may hamper the functionality of the whole splicing machinery ; this would consequently reduce , in dystrophic muscles , the capability of satellite cells to positively respond to anabolic stimuli . interestingly , experimental therapeutic approaches for dm1 aimed at reducing intranuclear sequestration of splicing factors demonstrated that the restoration of normal splicing processes represents a key passage for alleviating disease symptoms . it has been reported that alteration of the rna pathways does not affect the fusion process , so that cultured dm2 myoblasts are able to differentiate into myotubes as much as myoblasts from healthy subjects do . similarly , cultured myoblasts from aged healthy subjects are able to form myotubes in culture . this would suggest that the capability of cultured myoblasts to proliferate and differentiate is maintained in aged and dystrophic subjects . however , the present ultrastructural and cytochemical data demonstrate that significant differences exist for some cytological and functional characteristics in the myoblasts from healthy and dm2 patients , despite their similarities in proliferation rate and age in culture . interestingly , recent preliminary observations on the in vitro differentiation of dm2 myoblasts showed an early structural disorganization of the derived myotubes , especially the cytoskeletal apparatus , which may affect their functionality and survival . further studies are however needed to investigate in vitro myoblast differentiation and myotube survival in dm2 patients using both morphological and biomolecular analyses such as those previously used to characterise the differentiation process of c2c12 myoblast cell line . moreover , studies on the occurrence of senescence traits in both satellite cells and myofibres in dm2 muscle biopsies would provide important clues in the attempt to characterize the cellular mechanisms at the basis of muscle wasting in dm2 myotonic dystrophy .

myotonic dystrophy type 2 ( dm2 ) is an autosomal dominant disorder caused by the expansion of the tetranucleotidic repeat ( cctg)n in the first intron of the zinc finger protein-9 gene . in dm2 tissues , the expanded mutant transcripts accumulate in nuclear focal aggregates where splicing factors are sequestered , thus affecting mrna processing . interestingly , the ultrastructural alterations in the splicing machinery observed in the myonuclei of dm2 skeletal muscles are reminiscent of the nuclear changes occurring in age - related muscle atrophy . here , we investigated in vitro structural and functional features of satellite cell - derived myoblasts from biceps brachii , in the attempt to investigate cell senescence indices in dm2 patients by ultrastructural cytochemistry . we observed that in satellite cell - derived dm2 myoblasts , cell - senescence alterations such as cytoplasmic vacuolization , reduction of the proteosynthetic apparatus , accumulation of heterochromatin and impairment of the pre - mrna maturation pathways occur earlier than in myoblasts from healthy patients . these results , together with preliminary in vitro observations on the early onset of defective structural features in dm2 myoblast derived - myotubes , suggest that the regeneration capability of dm2 satellite cells may be impaired , thus contributing to the muscular dystrophy in dm2 patients .

confounding is a major concern in epidemiology . since the publication of the seminal paper by greenland and robins , many epidemiologists have explained the concept of confounding by examining risk measures under a simple potential - outcome ( or counterfactual ) model for a cohort of individuals . exchangeability of potential outcomes between the exposed and unexposed groups is one of the most fundamental assumptions in making causal inference , and confounding is a common source of lack of exchangeability . despite its significance , the different notions of confounding have not been fully appreciated in the literature , leading to confusion of causal concepts in epidemiology . this article aims to highlight the importance of differentiating between the subtly different notions of confounding from the perspective of counterfactual reasoning . we also show that directed acyclic graphs ( dags ) provide a simple algorithm to identify a sufficient set of confounders if the underlying causal structure is properly reflected . to achieve these goals the concept of response type is an essential foundation of causal inference because the causal effect of exposure on disease frequency in a population depends on the distribution of the response types of individuals in that population , not necessarily on the population distribution of the covariates . this point , however , has been relatively underappreciated because , despite its sophistication and usefulness , the response type of each individual is unobservable . to consider the effect of smoking cessation on lung cancer during a defined time period , we use an example of four subjects ( table 1 ) . in an epidemiologic study of these subjects , let us suppose that subjects # 1 ( male ) and # 3 ( female ) were actually exposed ( i.e. , quit smoking ) and subjects # 2 ( male ) and # 4 ( female ) were actually unexposed ( i.e. , did not quit smoking ) . during the follow - up , one of the exposed and both of the unexposed subjects suffered from lung cancer . consequently , the observed risk difference ( rd ) estimate for the effect of smoking cessation on lung cancer can be calculated as : 1/2 2/2 = 1/2 . likewise , the observed risk ratio ( rr ) estimate can be calculated as : ( 1/2)/(2/2 ) = 1/2 . when we consider a binary exposure and a binary outcome , individuals can be classified into the following four different response types.type 1 or doomed persons : exposure is irrelevant because outcome occurs with or without exposuretype 2 or causal persons : outcome occurs if and only if they are exposedtype 3 or preventive persons : outcome occurs if and only if they are unexposedtype 4 or immune persons : exposure is irrelevant because outcome does not occur with or without exposure type 1 or doomed persons : exposure is irrelevant because outcome occurs with or without exposure type 2 or causal persons : outcome occurs if and only if they are exposed type 3 or preventive persons : outcome occurs if and only if they are unexposed type 4 or immune persons : exposure is irrelevant because outcome does not occur with or without exposure response types of the four subjects are shown in table 1 . no subjects are classified as a causal response type , implying that the effect of smoking cessation is in the same direction for all four subjects . although monotonicity assumptions may be biologically plausible in some situations , they can never be empirically verified with data because they make reference to all individuals in the population . here the conditions presented in our paper can be used even when the monotonicity assumption is violated . in the following sections , we illustrate a typology of four notions of confounding by exploring and extending this simple example ( box 1 and fig . 1 ) . for simplicity , we use deterministic counterfactuals for each subject and assume that no random error attributable to sampling variability exists . confounding in distribution : we say that there is no confounding in distribution of the effect of exposure on outcome if the group that actually had a particular exposure is representative of what would have occurred had the entire target population been exposed to the same level of exposure.confounding in measure : we say that there is no confounding in measure of the effect of exposure on outcome if a particular measure of interest is equivalent to the corresponding causal measure in the target population.confounding in expectation : we say that there is no confounding in expectation of the effect of exposure on outcome if the exposure assignment mechanism results in balance.realized confounding : we say that there is no realized confounding of the effect of exposure on outcome if a particular exposure assignment results in balance , irrespective of the exposure assignment mechanism . confounding in distribution : we say that there is no confounding in distribution of the effect of exposure on outcome if the group that actually had a particular exposure is representative of what would have occurred had the entire target population been exposed to the same level of exposure . confounding in measure : we say that there is no confounding in measure of the effect of exposure on outcome if a particular measure of interest is equivalent to the corresponding causal measure in the target population . confounding in expectation : we say that there is no confounding in expectation of the effect of exposure on outcome if the exposure assignment mechanism results in balance . realized confounding : we say that there is no realized confounding of the effect of exposure on outcome if a particular exposure assignment results in balance , irrespective of the exposure assignment mechanism . the causal effect of exposure on disease frequency in a population depends on the distribution of response types of individuals in that population . table 2 shows the distribution of response types in the exposed and unexposed groups of the abovementioned example . we also show the distribution in the total population ; let pi , qi , and ri , i = 14 , be proportions of response type i in the exposed group , the unexposed group , and the total population , respectively . note that ri can be calculated as pi/2 + qi/2 because the numbers of the exposed and unexposed groups are balanced ( table 1 ) . among the exposed group , only type 1 and type 2 persons will develop the outcome , and the risk , or incidence proportion , of lung cancer in the exposed group is p1 + p2 . among the unexposed group , only type 1 and type 3 persons will develop the outcome , and the corresponding risk is q1 + q3 . therefore , the associational rd can be obtained using the proportions of response types as : ( p1 + p2 ) ( q1 + q3 ) = 1/2 2/2 = 1/2 , which is equivalent to the abovementioned observed rd estimate under the assumption of no sampling variability . effect of smoking cessation on lung cancer ( 1 = diseased , 0 = non - diseased ) . the associational risk difference is calculated as : ( p1 + p2 ) ( q1 + q3 ) = 1/2 2/2 = 1/2 . note that the distribution in this table applies to scenario # 2 in table 3 . causal risk difference in the exposed group is defined as : ( p1 + p2 ) ( p1 + p3 ) = p2 p3 = 0 0 = 0 . causal risk difference in the unexposed group is defined as : ( q1 + q2 ) ( q1 + q3 ) = q2 q3 = 0 as shown in table 1 , numbers of the exposed and unexposed groups are balanced , so a proportion of response type i in the total population , ri , can be calculated as : pi/2 + qi/2 . the causal risk difference in the total population is defined as : ( r1 + r2 ) ( r1 + r3 ) = r2 r3 = 0 2/4 = 2/4 . it has been well established that the target population concept plays a key role in discussions of causal inference in epidemiology . based on the distribution of these response types , we can define the true value of the causal parameters of interest in the corresponding target populations . for example , if exposure had been absent in the exposed group , only type 1 and type 3 persons would have developed the outcome , and the counterfactual risk of lung cancer would have been p1 + p3 . therefore , the causal rd in the exposed group ( i.e. , subjects # 1 and # 3 ) can be calculated as : ( p1 + p2 ) ( p1 + p3 ) = p2 p3 = 0 0 = 0 . likewise , the causal rds in the unexposed group ( i.e. , subjects # 2 and # 4 ) and the total population can be calculated as : ( q1 + q2 ) ( q1 + q3 ) = q2 q3 = 0 2/2 = 2/2 and ( r1 + r2 ) ( r1 + r3 ) = r2 r3 = 0 2/4 = 2/4 , respectively . these descriptions in terms of response types are valuable in highlighting the significance that the notion of confounding can be defined with respect to both the distribution of potential outcomes ( i.e. , confounding in distribution ) and a specific effect measure ( i.e. , confounding in measure ) . if we use rd as a measure of interest , when the exposed group is the target population , we say that there is confounding in measure if the causal rd in the exposed group ( i.e. , ( p1 + p2 ) ( p1 + p3 ) ) is not equivalent to the associational rd ( i.e. , ( p1 + p2 ) ( q1 + q3 ) ) . therefore , a sufficient and necessary condition for no confounding in measure is given by:(1)(p1+p2)(p1+p3)=(p1+p2)(q1+q3)(p1+p3)=(q1+q3),which is violated in table 2 . conversely , when the unexposed group is the target population , a sufficient and necessary condition for no confounding in measure is given by:(2)(q1+q2)(q1+q3)=(p1+p2)(q1+q3)(p1+p2)=(q1+q2),which is also violated in table 2 . note that these conditions can be also derived when the notion of confounding is defined with respect to the distribution of potential outcomes , rather than with respect to a specific effect measure . for example , when the exposed group is the target population , we say that there is confounding in distribution if the actual unexposed group is not representative of what would have occurred in the actual exposed group had they been unexposed . therefore , a sufficient and necessary condition for no confounding in distribution is identical to equation ( 1 ) . when the exposed and unexposed groups are used as target populations , distinguishing between the notions of confounding in distribution and confounding in measure becomes a subtle issue , and there is confounding in distribution and confounding in measure in table 2 . when the target is the total population , however , it is crucial to distinguish between these because conditions for no confounding vary according to the two notions of confounding . if we use the notion of confounding in distribution , a sufficient and necessary condition for no confounding is given by:(3){(r1+r2)=(p1+p2)}{(r1+r3)=(q1+q3)}{(p1+p2)=(q1+q2)}{(p1+p3)=(q1+q3)},which is obviously violated in table 2 . if equation ( 3 ) holds , the groups that are actually exposed and unexposed are representative of what would have occurred had the total population been exposed and unexposed , respectively . meanwhile , if we use rd as a measure of interest , a sufficient and necessary condition for no confounding in measure is given by:(4)(r1+r2)(r1+r3)=(p1+p2)(q1+q3)(p2+q2)/2(p3+q3)/2=(p1+p2)(q1+q3)(p1+p3)+(p1+p2)=(q1+q3)+(q1+q2),which is weaker than equation ( 3 ) and is met in table 2 . for example , if we use rr as a measure of interest , a sufficient and necessary condition for no confounding in measure is given by:(5)(r1+r2)/(r1+r3)=(p1+p2)/(q1+q3)[{(p1+q1)+(p2+q2)}/2]/[{(p1+q1)+(p3+q3)}/2]=(p1+p2)/(q1+q3)(p1+p2)(p1+p3)=(q1+q3)(q1+q2),which is , though weaker than equation ( 3 ) , violated in table 2 . consequently , even if the distribution of response types in the exposed and unexposed groups are not comparable ( i.e. , ( p1,p2,p3,p4 ) ( q1,q2,q3,q4 ) ) , as in table 2 , we may obtain an unconfounded estimate for the target population . complete comparability of response types between the exposed and unexposed groups ( i.e. , ( p1,p2,p3,p4 ) = ( q1,q2,q3,q4 ) ) is a sufficient , but not a necessary , condition for no confounding in the three target populations , irrespective of whether one uses the notion of confounding in distribution or confounding in measure . in conclusion , confounding depends not only on the population chosen as the target of inference , but also on the notion of confounding itself , when the target is the total population . this point has been relatively underappreciated , partly because some books ( including modern epidemiology and encyclopedia of epidemiology ) discuss the concept of confounding using only the exposed and unexposed groups as the target populations . as examples of the confusion surrounding the concept of confounding , a recent review article by gatto et al . explains the conditions for no confounding that are implicitly derived from the notion of confounding in distribution , whereas maldonado implicitly used the notion of confounding in measure when discussing the concept of confounding . to clarify the significance of differentiating the two notions of confounding , it would be helpful to use not only the exposed and unexposed groups , but also the total population as the target populations . as discussed in an update of the classic methodology paper by greenland and robins , a further distinction can be drawn between confounding in expectation and realized confounding . epidemiologic literature has typically addressed the issue of no confounding in the notion of realized confounding ; however , the notion of confounding in expectation is also valuable . the concept of bias is defined by comparing the expected value of an estimator and the true value of the parameter , and confounding is a common source of bias . in an ideal randomized controlled trial , the randomized groups will be comparable in their potential outcomes on average , over repeated experiments . for any given experiment , however , the particular randomization may result in imbalances by chance , because of the particular allocation or exposure assignment . such a scenario would result in no confounding in expectation but there would be realized confounding for that particular trial . confounding in expectation and realized confounding have been also referred to as confounded mechanisms and confounded assignments , respectively . to grasp the explicit distinction between these notions of confounding , we need to understand the mechanism that generates exposure events , not the product of that mechanism . in the example of four smokers , the lack of comparability of response types between the exposed and unexposed groups in the example could be because the configuration was observed randomly , with the estimator being unconfounded in expectation , or there could be a reason for the lack of comparability that is not revealed in the above explanation . to obtain the expected value of an estimator in the target population , we need to consider the distribution of exposure status in that population . to illustrate this , the following discussion focuses on the situation in which the target population is the total population . note that table 1 shows only one pattern of exposure status of the four subjects . given a total of four subjects , we can consider a maximum of six patterns of exposure status , when the numbers of the exposed and unexposed groups are balanced ( table 3 ) ( the exposure status shown in table 1 corresponds to scenario # 2 in table 3 . ) . in each scenario scenarios # 1 and # 3 are identical from the perspective of counterfactual reasoning , because the distributions of response types are the same in these scenarios . similarly , scenarios # 4 and # 6 are identical from the perspective of counterfactual reasoning . consequently , these six scenarios are grouped into a total of four patterns in terms of the distributions of response types . exposure status shown in table 1 corresponds to scenario # 2 . from the perspective of counterfactual reasoning , scenarios # 1 and # 3 in table 3 are essentially identical ; the distributions of response types in the exposed and unexposed groups are the same . therefore , the observed rd estimates are identical in these scenarios ( i.e. , 0 ) . similarly , scenarios # 4 and # 6 are essentially identical , because the distributions of response types in these scenarios are the same . as a result , the six scenarios can be grouped into a total of four patterns in terms of the distributions of response types . to highlight the distinction between confounding in expectation and realized confounding , we discuss two situations below , according to different mechanisms that generate the exposure events . in situation 1 , the treatment assignment is randomly determined , whereas , in situation 2 , the treatment assignment is causally influenced by the subject 's sex . see eappendix 1 and etable 1 , etable 2 , etable 3 , and etable 4 for a technical discussion of these situations . when the treatment assignment of each subject is randomly determined , we assume the probability of the two males quitting smoking is equal to the probability of the two females quitting smoking ( i.e. , p[quitting | male ] = p[quitting | female ] = 1/2 ) . in this situation , the six scenarios are induced randomly , with a probability of 1/6 ( table 4 ) . probability of the four subjects quitting smoking is 1/2 , so the six scenarios are induced randomly . probabilities of the two males and the two females quitting smoking are 2/3 and 1/3 , respectively , so scenario # 1 is expected to occur 16 times ( i.e. , 2 ) as often as scenario # 6 . likewise , each of the scenarios # 25 is expected to occur four times ( i.e. , 2 ) as often as scenario # 6 . the expected values of the estimators for risk in the exposed and unexposed groups are calculated as : 3 ( 1/6 1/2 ) + 3 ( 1/6 0/2 ) = 1/4 and 3 ( 1/6 1/2 ) + 3 ( 1/6 2/2 ) = 3/4 , respectively ( table 4 ) . consequently , the expected value of the estimator for rd in the four subjects is calculated as : 1/4 3/4 = 1/2 , which is equivalent to the causal rd in the four subjects . in the notion of confounding in expectation , we say that there is no confounding in measure of the effect of smoking cessation on lung cancer in the four subjects ( i.e. , the second quadrant in fig . 1 ) . in this case , we describe the estimator as being an unbiased estimator and the realized value is referred to as an unbiased estimate . using the notion of confounding in expectation , each of the observed rd estimates in the six scenarios is referred to as an unbiased estimate for the four subjects , even if it is not equivalent to the causal rd in the four subjects . conversely , if the notion of realized confounding is used , we simply compare the observed rd estimate in each scenario with the causal rd in the four subjects . although there is no realized confounding in measure in scenarios # 2 and # 5 , there is realized confounding in measure in scenarios # 1 , # 3 , # 4 , and # 6 ( i.e. , the third quadrant in fig . 1 ) . this clearly demonstrates that realized confounding can be present even if the exposure assignment mechanism is completely random , especially if the study size is small . note that the expected values of the estimators for risk in the exposed and unexposed groups ( i.e. , 1/4 and 3/4 , respectively ) are equivalent to the risk if all four subjects had been exposed and unexposed , respectively ( table 4 ) . in the notion of confounding in expectation , there is no confounding in distribution of the effect of smoking cessation on lung cancer in the four subjects ( i.e. , the first quadrant in fig . 1 ) . conversely , if the notion of realized confounding is used in table 1 , the observed risk in the exposed group ( i.e. , 1/2 ) is not equivalent to the risk if all four subjects had been exposed ( i.e. , 1/4 ) . the observed risk of the unexposed group ( i.e. , 2/2 ) is not equivalent to the risk if all four subjects had been unexposed ( i.e. , 3/4 ) . in the notion of realized confounding , there is confounding in distribution ( i.e. , the fourth quadrant in fig , we consider a situation in which the treatment assignment of each subject is influenced by his or her sex . for example , the probability of the two males quitting smoking is twice as high as the probability of the two females quitting smoking ( i.e. , p[quitting | male ] = 2/3 and p[quitting | female ] = 1/3 ) . consequently , scenario # 1 is expected to occur 16 times ( i.e. , 2 ) as often as scenario # 6 . likewise , each of the scenarios # 25 is expected to occur four times ( i.e. , 2 ) as often as scenario # 6 . in other words , scenario # 1 is expected to occur with a probability of 16/33 ; each of the scenarios # 25 is expected to occur with a probability of 4/33 ; and scenario # 6 is expected to occur with a probability of 1/33 ( table 4 ) . the expected values of the estimators for risk in the exposed and unexposed groups are calculated as : ( 16/33 1/2 ) + 2 ( 4/33 1/2 ) + 2 ( 4/33 0/2 ) + ( 1/33 0/2 ) = 4/11 and ( 16/33 1/2 ) + 2 ( 4/33 2/2 ) + 2 ( 4/33 1/2 ) + ( 1/33 2/2 ) = 7/11 , respectively ( table 4 ) . consequently , the expected value of the estimator for rd in the four subjects are calculated as : 4/11 7/11 = 3/11 , which is not equivalent to the causal rd in the four subjects ( i.e. , 1/2 ) . in this case , the estimator is a biased estimator , and the differential between the two values ( i.e. , 3/11 ( 1/2 ) = 5/22 ) is called bias . in situation 2 , the observed rd estimate in table 1 ( i.e. , 1/2 ) is confounded in the notion of confounding in expectation ( i.e. , the second quadrant in fig . 1 ) , although it is equivalent to the causal rd in the four subjects . in contrast , in the notion of realized confounding , there is no confounding in measure of the effect of smoking cessation on lung cancer in the four subjects ( i.e. , the third quadrant in fig . 1 ) . when examining the presence of confounding in distribution , the expected values of the estimators for risk in the exposed and unexposed groups ( i.e. , 4/11 and 7/11 , respectively ) are not equivalent to the risk had all four subjects been exposed and unexposed , respectively ( table 4 ) . in the notion of confounding in expectation , there is confounding in distribution of the effect of smoking cessation on lung cancer in the four subjects ( i.e. , the first quadrant in fig . 1 ) . using the notion of realized confounding in table 1 , there is also confounding in distribution of the effect of smoking cessation on lung cancer in the four subjects ( i.e. , the fourth quadrant in fig . 1 ) . a simple example to clarify the distinction between confounding in expectation and realized confounding is a useful educational tool to explain the concept of confounding more clearly . however , it is important to note that the exposed and unexposed groups are , by definition , determined by the specific pattern of exposure status . if these subpopulations are used as target populations , the discussion is logically restricted to the notion of realized confounding for the two target populations in that particular pattern . therefore , to teach a generalized concept of bias , it is important to use the total population as the target population , as this facilitates the differentiation between notions of confounding in expectation and realized confounding . as pointed out in a recent review by schwartz et al . , there are discrepancies in the literature regarding whether random error should be included as a bias . part of the confusion stems from lack of appreciation of the distinction between the notions of confounding in expectation and realized confounding . similarly , the notion of confounding in expectation is essential to understand the relationship between accuracy , validity , and precision . see eappendix 2 for further discussion , including a numerical description of the relationships in situations 1 and 2 . in epidemiologic research , dags have been used extensively to determine the variables for which it is sufficient to control for confounding to estimate causal effects . in this section , we graphically illustrate this point , highlighting the usefulness of dags in examining the presence of confounding in distribution in the notion of confounding in expectation ( i.e. , the first quadrant in fig . 1 ) . the presence of a dashed arrow from male to smoking cessation is determined by comparing the probability of the two males quitting smoking ( i.e. , p[quitting | male ] ) and the probability of the two females quitting smoking ( i.e. , p[quitting | female ] ) . this is explained simply , using the two previously discussed situations . when the treatment assignment of the four subjects is randomly determined ( i.e. , p[quitting | male ] = p[quitting | female ] = 1/2 ) , male and smoking cessation are independent ; there is no association between these two events . the dashed arrow from male to smoking cessation in fig . 2 is absent , and there is no backdoor path ( i.e. , a non - causal path that has an arrow pointing into the exposure ) from smoking cessation to lung cancer . consistent with our explanation in the previous section , in the notion of confounding in expectation , when the target population is the total population , bias does not occur in situation 1 ; there is no confounding in distribution . when the treatment assignment of the four subjects are influenced by their sex ( i.e. , p[quitting | male ] p[quitting | female ] ) , male and smoking cessation are not independent ; there is a causal association between these two events . the dashed arrow from male to smoking cessation in fig . 2 is present , resulting in a backdoor path from smoking cessation to lung cancer . consistent with our explanation in the previous section , in the notion of confounding in expectation , when the target population is the total population , bias occurs in situation 2 ; there is confounding in distribution . dags are primarily useful to examine the presence of confounding in distribution in the notion of confounding in expectation ( i.e. , the first quadrant in fig . 1 ) . they are also practical tools to identify realized confounding , if the size of population is large enough . furthermore , it has been shown that dags with signed edges , or signed dags , are useful in drawing conclusions about the direction of bias because of unmeasured confounders ( fig . 2 ) . finally , although the causal effect of exposure on disease frequency in a population depends on the distribution of response types of individuals in that population , and dags have been used to provide visual summaries of hypothetical relationships among variables , they do not describe the relationships between underlying response types . to overcome this , suzuki et al . discussed how dags can be extended by integrating response types and observed variables , showing the conceptual link between unobservable response types and observed ( or observable ) data frequencies in the population . as an example of their usefulness , the principal stratification approach can be illustrated using extended dags . in this paper , we provide a typology of the four notions of confounding in epidemiology from the perspective of counterfactual reasoning . in etable 5 , we summarize sufficient and necessary conditions for no confounding in terms of response types , when the target population is the total population . confounding in expectation is dependent on each mechanism that generates exposure events , whereas realized confounding is dependent on each product of that mechanism ( or scenario ) . in both the notions of confounding in expectation and realized confounding , no confounding in distribution is a sufficient condition for no confounding in measure , irrespective of whether rd or rr are used as a measure of interest . both confounding and selection bias result in a lack of exchangeability , and comparable conditions apply to selection bias . the different notions of confounding have not been fully appreciated in the literature , which has led to confusion of causal concepts in epidemiology . this lack of clear understanding could lead to inappropriate use of and underappreciation of dags , which provide a simple algorithm for examining the presence of confounding in distribution in the notion of confounding in expectation . for simplicity , throughout this paper we have ignored that causal effects estimated in one population are often intended for use in making decisions in another population . transportability of the causal effect , and this is a question of external validity . when transporting the causal effect estimates to external targets , we need to consider the distributions of effect modifiers , interference patterns , and versions of treatment across populations . although we have focused on the three usual internal target populations ( i.e. , the exposed group , the unexposed group , and the total population ) , our discussion about the notions of confounding analogously applies when using external targets . the potential outcomes and causal graph frameworks are also relevant , as they are for internal targets . simple examples can be powerful tools for understanding complex causal concepts ; the power of simplicity , however , should be carefully exercised to achieve this goal . recent developments in epidemiologic methods have demonstrated that substantial insight can be obtained from simplified representations of complex biological reality . none of us would deny the value of an old dictum ( often referred to as occam 's razor ) that one should not introduce needless complexity for purposes of prediction or explanation . undeniably , however , all of us should also keep in mind einstein 's razor , the warning against being too simplistic : everything should be made as simple as possible , but not simpler . we hope that our simple example can serve as an effective tool to illustrate a typology of notions of confounding .

confounding is a major concern in epidemiology . despite its significance , the different notions of confounding have not been fully appreciated in the literature , leading to confusion of causal concepts in epidemiology . in this article , we aim to highlight the importance of differentiating between the subtly different notions of confounding from the perspective of counterfactual reasoning . by using a simple example , we illustrate the significance of considering the distribution of response types to distinguish causation from association , highlighting that confounding depends not only on the population chosen as the target of inference , but also on the notions of confounding in distribution and confounding in measure . this point has been relatively underappreciated , partly because some literature on the concept of confounding has only used the exposed and unexposed groups as the target populations , while it would be helpful to use the total population as the target population . moreover , to clarify a further distinction between confounding in expectation and realized confounding , we illustrate the usefulness of examining the distribution of exposure status in the target population . to grasp the explicit distinction between confounding in expectation and realized confounding , we need to understand the mechanism that generates exposure events , not the product of that mechanism . finally , we graphically illustrate this point , highlighting the usefulness of directed acyclic graphs in examining the presence of confounding in distribution , in the notion of confounding in expectation .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Internet Minors Protection and Cyberspace Technology Act''. SEC. 2. COMPUTER SOFTWARE REQUIRED. (a) Installation Required.--Any elementary or secondary school or public library that has received under any program or activity of any Federal agency any funds for the acquisition or operation of any computer that is accessible to minors and that has access to the Internet, or that has received universal service assistance under section 254(h)(1)(B) of the Communications Act of 1934 for accessing the Internet on any computer that is accessible to minors, shall-- (1) install software on that computer that is determined (in accordance with subsection (b)) to be adequately designed to prevent minors from obtaining access to any obscene information or child pornography using that computer; and (2) ensure that such software is operational whenever that computer is used by minors, except that such software's operation may be temporarily interrupted to permit a minor to have access to information that is not obscene, is not child pornography, or is otherwise unprotected by the Constitution under the direct supervision of an adult designated by such school or library. (b) Determination of Adequate Design.--For any elementary or secondary school or public library within the jurisdiction of any State, the determinations required for purposes of subsection (a)(1) shall be made by an agency or official designated by the chief executive officer of such State. For any elementary or secondary school or public library that is not within the jurisdiction of any State, the determinations required for purposes of subsection (a)(1) shall be made by the Secretary of Education. (c) Consequences of Violations.-- (1) Use of general education provisions act remedies.-- Whenever the head of any Federal agency has reason to believe that any recipient of funds under any program or activity is failing to comply substantially with the requirements of subsection (a), the head of such agency may-- (A) withhold further payments under that program or activity, (B) issue a complaint to compel compliance through a cease and desist order, or (C) enter into a compliance agreement with a recipient to bring it into compliance, in the same manner as the Secretary of Education is authorized to take such actions under sections 455, 456, and 457, respectively, of the General Education Provisions Act (20 U.S.C. 1234d). (2) Recovery of funds prohibited.--The actions authorized by paragraph (1) are the exclusive remedies available with respect to a violation of subsection (a), and the head of any Federal agency shall not seek a recovery of funds from the recipient. (d) Definitions.--For purposes of this section: (1) Elementary or secondary school.--The term ``elementary or secondary school'' means an elementary school or a secondary school as such terms are defined in section 14101 of the Elementary and Secondary Education Act of 1965 (20 U.S.C. 8801). (2) Public library.--The term ``public library'' means has the meaning given the term ``library'' by section 213 of the Library Services and Technology Act (20 U.S.C. 9122). (3) Computer.--The term ``computer'' includes any hardware, software, or other technology attached or connected to, installed in, or otherwise used in connection with a computer. (4) Access to internet.--A computer shall be considered to have access to the Internet if such computer is equipped with a modem or is connected to a computer network which has access to the Internet. (5) Acquisition or operation.--A elementary or secondary school or public library shall be considered to have received under a program or activity of any Federal agency any funds for the acquisition or operation of any computer if such funds are used in any manner, directly or indirectly-- (A) to purchase, lease, or otherwise acquire or obtain the use of such computer, or (B) to obtain services, supplies, software, or other actions or materials to support, or in connection with, the operation of such computer. (6) Federal agency.--The term ``Federal agency'' has the meaning given the term `agency' by section 551(1) of title 5, United States Code. (7) State.--The term ``State'' means each of the 50 States, the District of Columbia, the Commonwealth of Puerto Rico, the Virgin Islands, Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, the Republic of the Marshall Islands, the Federated States of Micronesia, and the Republic of Palau. (8) Child pornography.--The term ``child pornography'' has the meaning provided in section 2256(8) of title 18, United States Code.

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animal studies have demonstrated that the expression of inducible nitric oxide synthase ( inos ) was increased in ischemia - reperfused myocardium , resulting in increased production of nitric oxide ( no ) and superoxide anions . it is well known that no is protective for the cardiovascular system and excessive no exerts negative effects on the circulatory system . for instance , peroxynitrite anion formed from the no and superoxide anion is a strongly cytotoxic substance and plays an important role in the occurrence of some forms of acute myocardial damage . therefore , myocardial ischemia - reperfusion injury might be alleviated by inhibiting excessive no production . nonetheless , it has been demonstrated that the left ventricular ejection fraction progressively declined in in vivo experiments when the non - selective nos inhibitor n - nitro - l - arginine methyl ester ( name ) was administered . the possible reason for this is that myocardial blood flow perfusion was impaired due to the inhibition of coronary arterial endothelial nos ( enos ) by name . we hypothesized that the selective inos inhibitor aminoguanidine ( amd ) , in contrast to name , would alleviate the impairment of the myocardial blood flow perfusion through inhibition of inos - mediated no . to test this hypothesis , we attempted to compare the effects between selective and non - selective nos inhibitors on myocardial blood flow perfusion in an in vivo canine experimental model of myocardial ischemia - reperfusion . the protocol was approved by the experimental animal ethics committee of nanfang hospital , southern medical university , guangzhou , china , according to the guidelines for animal experiments established by the chinese association for laboratory animal science . animals were randomly divided into 4 groups : only ischemia - reperfusion ( control ) group , ischemia - reperfusion plus name - treated group , ischemia - reperfusion plus amd - treated group , and sham operation group . after the animal was anaesthetized using intravenous sodium pentobarbital at 35 mg / kg , trachea cannula was performed and linked to an animal respirator . then a pigtail catheter was inserted into the right femoral artery for aortic and left ventricular pressure measurement . an expansion tube sheath was placed into the right femoral vein for infusion and ultrasound contrast injection . another suture line was placed across the left anterior descending coronary artery ( lad ) with a water sac laid on the surface of the heart . lad ligation for 60 min was performed in the 3 treatment groups , followed by 120 min of reperfusion , and no ligation was performed in the sham operation group . in the name - treated group , administration of one - third dosage of name started 10 min before lad ligation , and continuously intravenous name of the remaining dosage initiated from 10 min before reperfusion to the end of 120 min reperfusion . in amd - treated group , the animals received intravenous amd at 100 mg / kg . administration of one - third dosage amd started 10 min before lad ligation , and continuously intravenous amd of the remaining dosage was initiated from 10 min before reperfusion to the end of 120 min reperfusion . sequoia 512 ultrasound machine ( siemens ag , munich , germany ) with 3.5-mhz frequency , the horizontal short - axis view map of the left ventricular papillary muscle was displayed by the transducer fixed into the water sac . the transducer was immobilized during the whole experiment and the quality of the image was maintained by adjusting signal gains . at each time , a bolus of 0.01 ml / kg microvesicle contrast octafluoropropane ( c3f8)-exposed sonicated dextrose albumin ( department of clinical pharmacy , nanfang hospital , guangzhou , china ) was injected intravenously and ultrasound images were recorded for further analysis . mce time - points included prior to lad ligation , immediately before reperfusion , and at 5 , 30 , 60 , 90 , and 120 min reperfusion . the regions of interest were the anterior wall of the left ventricle but excluding the endocardium or epicardium membrane . the regions were then automatically analyzed by the program and finalized as a videointensity - time curve after background subtraction ( figure 1 ) . myocardial perfusion was indicated by peak videointensity ( pvi ) [ 68 ] and relative perfusion of the ischemia - reperfusioned district was represented by the ratio of pvi between ischemia - reperfusioned and intact myocardium zones ( pvir ) . mce curve width was defined as the duration from the emergence of myocardial development to the myocardial videointensity of 10% pvi back from pvi . at the individual mce time - points , blood samples of 5 ml each time were taken from coronary venous sinus . nitrate and nitrite in plasma were measured by the nitrate reductase method ( kits were purchased from nanjing juli biomedical engineering institute , nanjing , china ) and stood for plasma concentrations of no . data are expressed as the mean value the standard deviation ( sd ) for continuous variables following a normal distribution , and one - way analysis of variance ( anova ) was used for comparisons of them . the protocol was approved by the experimental animal ethics committee of nanfang hospital , southern medical university , guangzhou , china , according to the guidelines for animal experiments established by the chinese association for laboratory animal science . animals were randomly divided into 4 groups : only ischemia - reperfusion ( control ) group , ischemia - reperfusion plus name - treated group , ischemia - reperfusion plus amd - treated group , and sham operation group . after the animal was anaesthetized using intravenous sodium pentobarbital at 35 mg / kg , trachea cannula was performed and linked to an animal respirator . then a pigtail catheter was inserted into the right femoral artery for aortic and left ventricular pressure measurement . an expansion tube sheath was placed into the right femoral vein for infusion and ultrasound contrast injection . another suture line was placed across the left anterior descending coronary artery ( lad ) with a water sac laid on the surface of the heart . lad ligation for 60 min was performed in the 3 treatment groups , followed by 120 min of reperfusion , and no ligation was performed in the sham operation group . in the name - treated group , administration of one - third dosage of name started 10 min before lad ligation , and continuously intravenous name of the remaining dosage initiated from 10 min before reperfusion to the end of 120 min reperfusion . in amd - treated group , the animals received intravenous amd at 100 mg / kg . administration of one - third dosage amd started 10 min before lad ligation , and continuously intravenous amd of the remaining dosage was initiated from 10 min before reperfusion to the end of 120 min reperfusion . using the acuson sequoia 512 ultrasound machine ( siemens ag , munich , germany ) with 3.5-mhz frequency , the horizontal short - axis view map of the left ventricular papillary muscle was displayed by the transducer fixed into the water sac . the transducer was immobilized during the whole experiment and the quality of the image was maintained by adjusting signal gains . the trigger electrocardiographic ( ecg ) interval was up to 3 cardiac cycles . at each time , a bolus of 0.01 ml / kg microvesicle contrast octafluoropropane ( c3f8)-exposed sonicated dextrose albumin ( department of clinical pharmacy , nanfang hospital , guangzhou , china ) was injected intravenously and ultrasound images were recorded for further analysis . mce time - points included prior to lad ligation , immediately before reperfusion , and at 5 , 30 , 60 , 90 , and 120 min reperfusion . the regions of interest were the anterior wall of the left ventricle but excluding the endocardium or epicardium membrane . the regions were then automatically analyzed by the program and finalized as a videointensity - time curve after background subtraction ( figure 1 ) . myocardial perfusion was indicated by peak videointensity ( pvi ) [ 68 ] and relative perfusion of the ischemia - reperfusioned district was represented by the ratio of pvi between ischemia - reperfusioned and intact myocardium zones ( pvir ) . mce curve width was defined as the duration from the emergence of myocardial development to the myocardial videointensity of 10% pvi back from pvi . at the individual mce time - points , blood samples of 5 ml each time were taken from coronary venous sinus . nitrate and nitrite in plasma were measured by the nitrate reductase method ( kits were purchased from nanjing juli biomedical engineering institute , nanjing , china ) and stood for plasma concentrations of no . data are expressed as the mean value the standard deviation ( sd ) for continuous variables following a normal distribution , and one - way analysis of variance ( anova ) was used for comparisons of them . six dogs were used in both the amd - treated and sham groups with no deaths and 8 dogs were killed in both the control and name - treated groups with 2 deaths for each , thus 6 dogs completed the experiment in each group . all the 4 deaths were due to ventricular fibrillation in the early period of reperfusion . none of the animals showed other complications except that visible ventricular premature beats during lad ligation was noticed . during lad ligation , no contrast filling in focal ventricular wall was found using mce with wall akinesis and thinning in two - dimensional ultrasound images . after release from lad ligation , adequate contrast filling was observed in the ventricular wall zone in which there was no contrast filling during lad ligation . although the wall motion improved with reperfusion , a complete recovery of the function was not noted at the end of the 120-min reperfusion . the model was accepted as reliable because no myocardial infarction was observed in myocardial 2,3,5-triphenyltetrazolium chloride ( ttc ) staining . hemodynamics monitoring displayed reduced heart rate during reperfusion and elevated mean aortic pressure prior to and during reperfusion in the name - treated group and no significant changes in other groups . left ventricular diastolic pressure markedly rose before and in early reperfusion in the control and name - treated groups and restored to their pre - ligation levels by 60- and 90-min reperfusion , respectively . in the amd - treated group , left ventricular diastolic pressure went up only prior to reperfusion . in the control group , pvi of reperfused myocardium markedly increased in the early reperfusion ( within 30-min reperfusion ) and thereafter returned to the pre - ligation level ( table 1 ) . in the name - treated group , pvi was only slightly higher than the pre - ligation level at 5 min reperfusion ( p>0.05 ) , but was significantly lower than the pre - ligation level from 30 to 120 min reperfusion . in the amd - treated group , pvi was significantly higher than the pre - ligation level only at 5 min reperfusion , and was insignificantly different from the pre - ligation level at other reperfusion time - points . a comparison of pvi at each corresponding reperfusion time - point among groups showed that pvi in the control group was higher than in the amd - treated group , which was higher than in the name - treated group but without statistical significance . the change of pvir in all groups was similar to that of pvi ( table 2 ) . a comparison among all groups showed that pvir was remarkably lower than the control group at 60 min reperfusion in the name - treated group and at 30 min reperfusion in the amd - treated group . furthermore , pvirs in the name - treated group were significantly lower than in the amd - treated group from 30 to 120 min reperfusion . mce curve width during reperfusion in the control group increased markedly and restored slowly , but not to the pre - ligation level by 120 min reperfusion ( table 3 ) . in the name - treated group , mce curve width was greater than in the control group and no restoration was observed . in the amd - treated group , mce curve width increased in the early reperfusion , but restored rapidly and reached the pre - ligation level by 90 min reperfusion . plasma no concentrations in the control group were increased during reperfusion and did not returned to the pre - ligation level by 120 min reperfusion ( table 4 ) . the no concentrations in the name - treated group greatly decreased and remained low during the whole period of reperfusion and notably lower than in the control group . in the amd - treated group , there were slight increases in no concentrations during reperfusion , but the differences versus their pre - ligation levels were not statistically significant . in the sham group , no significant changes in no levels were observed during the whole experiment ( tables 14 ) . six dogs were used in both the amd - treated and sham groups with no deaths and 8 dogs were killed in both the control and name - treated groups with 2 deaths for each , thus 6 dogs completed the experiment in each group . all the 4 deaths were due to ventricular fibrillation in the early period of reperfusion . none of the animals showed other complications except that visible ventricular premature beats during lad ligation was noticed . during lad ligation , no contrast filling in focal ventricular wall was found using mce with wall akinesis and thinning in two - dimensional ultrasound images . after release from lad ligation , adequate contrast filling was observed in the ventricular wall zone in which there was no contrast filling during lad ligation . although the wall motion improved with reperfusion , a complete recovery of the function was not noted at the end of the 120-min reperfusion . the model was accepted as reliable because no myocardial infarction was observed in myocardial 2,3,5-triphenyltetrazolium chloride ( ttc ) staining . hemodynamics monitoring displayed reduced heart rate during reperfusion and elevated mean aortic pressure prior to and during reperfusion in the name - treated group and no significant changes in other groups . left ventricular diastolic pressure markedly rose before and in early reperfusion in the control and name - treated groups and restored to their pre - ligation levels by 60- and 90-min reperfusion , respectively . in the amd - treated group , left ventricular diastolic pressure went up only prior to reperfusion . in the control group , pvi of reperfused myocardium markedly increased in the early reperfusion ( within 30-min reperfusion ) and thereafter returned to the pre - ligation level ( table 1 ) . in the name - treated group , pvi was only slightly higher than the pre - ligation level at 5 min reperfusion ( p>0.05 ) , but was significantly lower than the pre - ligation level from 30 to 120 min reperfusion . in the amd - treated group , pvi was significantly higher than the pre - ligation level only at 5 min reperfusion , and was insignificantly different from the pre - ligation level at other reperfusion time - points . a comparison of pvi at each corresponding reperfusion time - point among groups showed that pvi in the control group was higher than in the amd - treated group , which was higher than in the name - treated group but without statistical significance . the change of pvir in all groups was similar to that of pvi ( table 2 ) . a comparison among all groups showed that pvir was remarkably lower than the control group at 60 min reperfusion in the name - treated group and at 30 min reperfusion in the amd - treated group . furthermore , pvirs in the name - treated group were significantly lower than in the amd - treated group from 30 to 120 min reperfusion . mce curve width during reperfusion in the control group increased markedly and restored slowly , but not to the pre - ligation level by 120 min reperfusion ( table 3 ) . in the name - treated group , mce curve width was greater than in the control group and no restoration was observed . in the amd - treated group , mce curve width increased in the early reperfusion , but restored rapidly and reached the pre - ligation level by 90 min reperfusion . plasma no concentrations in the control group were increased during reperfusion and did not returned to the pre - ligation level by 120 min reperfusion ( table 4 ) . the no concentrations in the name - treated group greatly decreased and remained low during the whole period of reperfusion and notably lower than in the control group . in the amd - treated group , there were slight increases in no concentrations during reperfusion , but the differences versus their pre - ligation levels were not statistically significant . in the sham group , no significant changes in no levels were observed during the whole experiment ( tables 14 ) . the main findings of the present study are that no production by ischemia - reperfused myocardium increased , that the non - selective nos inhibitor name caused insufficiency of myocardial blood flow perfusion , and that the selective inos inhibitor aminoguanidine could retain a normal level of myocardial blood perfusion . these cytokines could stimulate multiple cells in myocardium expressing inos and then persistently produce a large quantity of no . recent studies have found that the blood flow perfusion of ischemia - reperfused myocardium did not decline , and instead even congested . this phenomenon was considered as responsive congestion to reperfusion following ischemia ; excessive no production may contribute to this . the present study showed that coronary sinus plasma no levels in an in vivo canine model of ischemia - reperfusion notably increased and that the blood perfusion of ischemia - reperfused myocardium also markedly increased . these findings further confirmed the increase of no production and responsive congestion in ischemia - reperfused myocardium . peroxynitrite anion , a strongly cytotoxic agent formed by the reaction of no with superoxide anion , can directly damage cardiac myocytes . in addition , the increase of mce curve width during reperfusion suggests intramyocardial microcirculatory stagnation . as such , we speculate that the use of nos inhibitors could alleviate myocardial ischemia - reperfusion injury through restraining excessive production of no . name is a type of non - selective nos inhibitor that inhibits both enos and inos . nonetheless , concomitant inhibition of coronary arterial enos will impair myocardial blood perfusion and then aggravate myocardial injury . studies have established that no produced through the enos route during ischemia - reperfusion is protective to myocardium . it was reported that the use of name brought about progressive decline of left ventricular ejection fraction . the present study shows that name totally inhibited the no production of ischemia - reperfused myocardium and remarkably reduced the myocardial blood flow perfusion to a lower than normal level that resulted in myocardial re - ischemia , which shows that name could cause myocardial hypoperfusion . administration of name brought about further increase of widened mce curve width during reperfusion , suggesting the aggravation of intramyocardial microcirculatory stagnation . therefore , non - selective nos inhibitors administrated in the settings of ischemia - reperfusion might be deleterious . wildhirt et al . found that cardiac dysfunction developed accompanied with increased myocardial inos activity , whereas aminoguanidine significantly inhibited inos activity and improved left ventricular function in a rabbit model of myocardial stunning . the present study shows that aminoguanidine inhibited excessive no production in ischemia - reperfused myocardium and then reduced only the degree of myocardial blood hyperperfusion and kept normal blood flow perfusion . furthermore , it relieved intramyocardial microcirculatory stagnation and accelerated its restoration to a normal level . these findings suggest that because it did not inhibited enos , aminoguanidine overcame the disadvantages of name , alleviating myocardial blood perfusion impairment and microcirculatory stagnation aggravation . selective inos inhibitor aminoguanidine , therefore , may be beneficial if used in the settings of ischemia - reperfusion . it can also display the spatial distribution of myocardial blood perfusion , measure myocardial blood flow and blood volume , and evaluate coronary blood flow reserve and endothelial function [ 1315 ] . compared with single - photon emission computed tomography imaging , mce provides a similar image of blood flow . using mce , the pvi was closely related to the myocardial blood flow measured by radio - microspheres or ultrasonic flowmeter . porter et al . reported a linear relationship between the coronary blood flow and the myocardial videointensity generated by the intravenous injection of fluoride carbon contrast agent . the sensitivity and reliability of mce for evaluating myocardial blood perfusion and coronary microcirculation have significantly improved with the improvement of acoustic contrast agents , the application of a second harmonic imaging technology , and the advance in analytical methods for mce images . mce is now considered one of the most effective methods for evaluation of myocardial microvascular dysfunction . administration of name totally inhibited no production and attenuated myocardial blood flow perfusion and aminoguanidine significantly relieved the increase in no production and alleviated the congestion of reperfused myocardium in a dog model . selective inhibitors of inos may be useful in the management of certain diseases associated with ischemia - reperfusion .

backgroundnitric oxide ( no ) is protective for the cardiovascular system , and excessive no exerts negative effects on the circulatory system . this study aimed to compare the effects of selective or non - selective no synthase ( nos ) inhibitors on blood flow perfusion of ischemia - reperfused myocardium.materials/methodsmale mongrel dogs were randomly assigned to 4 groups : only ischemia - reperfusion ( control ) , ischemia - reperfusion plus n-nitro - l - arginine methyl ester ( name ) treatment , ischemia - reperfusion plus aminoguanidine ( amd ) treatment , and sham operation group . myocardial contrast echocardiography ( mce ) was performed . blood samples were taken for measurement of no . background - subtracted peak videointensity ( pvi ) and pvi ratio in myocardium were measured.resultsin the name - treated group , the pvi at 5 min reperfusion did not significantly differ from pre - lad - occlusion , but declined to and retained at a level obviously lower than the pre - lad - occlusion . in the amd - treated group , the pvi at 5 min reperfusion was significantly higher than at pre - lad - occlusion , and then restored to and remained at the pre - lad - occlusion level . the changes of pvi ratios in the 3 groups were similar to pvi values . in the amd - treated group , the curve width increased in the early reperfusion , but returned to the pre - lad - occlusion level at 90 min reperfusion . the plasma no concentration in the name - treated group greatly decreased and remained low during the whole period of reperfusion . in the amd - treated group , there were only slight increases in no concentrations during reperfusion.conclusionsname totally inhibited no production and attenuated myocardial blood flow perfusion . aminoguanidine significantly relieved the increase in no production and alleviated the congestion of reperfused myocardium . selective inhibitors of inos might be useful in the management of certain diseases associated with ischemia - reperfusion .

Here is a complete transcript of President Obama’s news conference in the East Room of the White House on Nov. 14, 2012. Topics included the fiscal cliff, tax reform, the Petraeus scandal, immigration, the Benghazi attacks, Susan Rice, climate change and Syria. Read More: Obama faces array of questions at White House news conference PRESIDENT OBAMA: Good afternoon, everybody. Please have a seat. I hear you have some questions for me. View Graphic President Obama carried fewer states in 2012 than he did four years ago. He won a second term by dominating the nation’s large urban areas — although mostly by smaller margins compared to his 2008 vote totals. (LAUGHTER) But, let me just make a few remarks at the top and then I’ll open it up. First of all, I want to reiterate what I said on Friday. Right now, our economy is still recovering from a very deep and damaging crisis, so our top priority has to be jobs and growth. We’ve got to build on the progress that we’ve made because this nation succeeds when we’ve got a growing, thriving middle class. OBAMA: And that’s the idea at the core of the plan that I talked about on the campaign trail over the last year: rewarding manufacturers and small businesses that create jobs here, not overseas; providing more Americans the chance to learn the skills that businesses are looking for right now; keeping this country at the forefront of research, technology and clean energy; putting people back to work rebuilding our roads, our bridges and our schools; and reducing our deficit in a balanced and responsible way. Now, on this last item, we face a very clear deadline that requires us to make some big decisions on jobs, taxes and deficits by the end of the year. Both parties voted to set this deadline and I believe that both parties can work together to make these decisions in a balanced and responsible way. Yesterday, I had a chance to meet with labor and civic leaders for their input. Today, I’m meeting with CEOs of some of America’s largest companies. And I’ll meet with leaders of both parties of Congress before the week is out, because there’s only one way to solve these challenges and that is to do it together. As I’ve said before, I’m open to compromise and I’m open to new ideas, and I’ve been encouraged over the past week to hear Republican after Republican agree on the need for more revenue from the wealthiest Americans as part of our arithmetic if we’re going to be serious about reducing the deficit. Because when it comes to taxes, there are two pathways available. OBAMA: Option one, if Congress fails to act by the end of this year, everybody’s taxes will automatically go up, including the 98 percent of Americans who make less than $250,000 a year, and the 97 percent of small businesses who earn less than $250,000 a year. That doesn’t make sense. Our economy can’t afford that right now. Certainly, no middle class family can afford that right now. And nobody in either party says that they want it to happen. The other option is to pass a law right now that would prevent any tax hike whatsoever on the first $250,000 of everybody’s income. And by the way, that means every American, including the wealthiest Americans, get a tax cut. It means that 98 percent of all Americans and 97 percent of all small businesses won’t see their taxes go up a single dime. The Senate has already passed a law like this. Democrats in the House are ready to pass a law like this. And I hope Republicans in the House come on board too. We should not hold the middle class hostage, while we debate tax cuts for the wealthy. We should at least do what we agree on, and that’s to keep middle class taxes low. And I’ll bring everyone in to sign it right away, so we can give folks some certainty before the holiday season. I won’t pretend that figuring out everything else will be easy, but I’m confident we can do it, and I know we have to. I know that, that’s what the American people want us to do. That was a -- the very clear message from the election last week. And that was the message of a letter that I received over the weekend. It came from a man in Tennessee who began by writing that he didn’t vote for me. Which is OK. But, what he said was, even though he didn’t give me his vote, he’s giving me his support to move this country forward. And he said the same to his Republican representatives in Washington. He said that, he’ll back each of us regardless of party as long as we work together to make life better for all of us. And he made it clear that if we don’t make enough progress he’ll be back in touch. So my hope, he wrote, is that we can make progress in light of personal and party principles, special interest groups and years of business as usual. We’ve got to work together and put our differences aside. I couldn’t say it better myself. That’s precisely what I intend to do. And with that, let me open it up for your questions. And I’m gonna start off with Ben Feller of AP. QUESTION: Thank you, Mr. President. Can you assure the American people that there have been no breaches of national security or classified information in the scandal involving Generals Petraeus and Allen? And do you think that you as commander in chief and the American people should have been told that the CIA chief was under investigation before the election? OBAMA: Well, I have no evidence at this point from what I’ve seen that classified information was disclosed that in any way would have had a negative impact on our national security. Obviously, there’s an ongoing investigation. I don’t want to comment on the specifics of the investigation. The FBI has its own protocols in terms of how they proceed, and I’m gonna let rector Mueller and others examine those protocols and make some statements to the public generally. I do want to emphasize what I’ve said before. General Petraeus had an extraordinary career. He served this country with great distinction in Iraq, in Afghanistan and as head of the CIA. By his own assessment, he did not meet the standards that he felt were necessary as the director of CIA with respect to this personal matter that he is now dealing with with his family and with his wife. And it’s on that basis that he tendered his resignation and it’s on that basis that I accepted it. But I want to emphasize that from my perspective, at least, he has provided this country an extraordinary service. We are safer because of the work that Dave Petraeus has done. And my main hope right now is that he and his family are able to move on and that this ends up being a single side-note on what has otherwise been an extraordinary career. QUESTION: (inaudible). OBAMA: You know, again, I think you’re going to have to talk to the FBI in terms of what their general protocols are when it comes to what started off as a potential criminal investigation. You know, one of the challenges here is that we’re not supposed to meddle in, you know, criminal investigations and that’s been our practice. And, you know, I think that there are certain procedures that both the FBI follow or DOJ follow when they’re involved in these investigations. That’s traditionally been how we view things in part because people are innocent until proven guilty and we want to make sure that we don’t pre-judge these kinds of situations. OBAMA: And so my expectation is that they followed protocols that they already established. (CROSSTALK) QUESTION: Mr. President, on the fiscal cliff, two years ago, sir, you said that you wouldn’t extend the Bush-era tax cuts, but at the end of the day, you did. So, respectfully, sir, why should the American people and the Republicans believe that you won’t cave again this time? OBAMA: Well, two years ago the economy was in a different situation. We were still very much in the early parts of recovering from the worst economic crisis since The Great Depression, and ultimately we came together, not only to extend the Bush tax cuts, but also a wide range of policies that were going to be good for the economy at that point; unemployment insurance extensions, payroll tax extension, all of which made a difference and is part of the reason why what we’ve seen now is 32 consecutive months of job growth, and over 5.5 million jobs created, and the unemployment rate coming down. But what I said at the time is what I mean, which is this was a one-time proposition. And, you know what I had told leaders privately as well as publicly, is that we cannot afford to extend the Bush tax cuts for the wealthy. What we can do is make sure that middle-class taxes don’t go up. And so, the most important step we can take right now, and I think the foundation for a deal that helps the economy, creates jobs, gives consumers certainty, which means gives businesses confidence that they’re going to have consumers during the holiday season is if we right away say, 98 percent of Americans are not going to see their taxes go up, 97 percent of small businesses are not going to see their taxes go up. If we get that in place, we are actually removing half of the fiscal cliff. Half of the danger to our economy is removed by that single step. And what we can then do is shape a process whereby we look at tax reform -- which I’m very eager to do. I think we can simplify our tax system. I think we can make it more efficient. We can eliminate loopholes and deductions that have a distorting effect on our economy. I believe that we have to continue to take a serious look at how we reform our entitlements, because health care costs continue to be the biggest driver of our deficits. So there is a package to be shaped, and I’m confident that parties -- folks of goodwill in both parties can make that happen. But what I’m not going to do is to extend Bush tax cuts for the wealthiest 2 percent that we can’t afford and, according to economists, will have the least positive impact on our economy. QUESTION: You’ve said that the wealthiest must pay more. Would closing loopholes instead of raising rates for them satisfy you? OBAMA: I think that there are loopholes that can be closed, and we should look at how we can make the process of deductions, the filing process easier, simpler. But when it comes to the top 2 percent, what I’m not going to do is to extend further a tax cut for folks who don’t need it, which would cost close to a trillion dollars. And it’s very difficult to see how you make up that trillion dollars -- if we’re serious about deficit reduction -- just by closing loopholes and deductions. You know, the math tends not to work. And I think it’s important to establish a basic principle that was debated extensively during the course of this campaign. OBAMA: I mean, this shouldn’t be a surprise to anybody. This was -- if there was one thing that everybody understood was a big difference between myself and Mr. Romney, it was, when it comes to how we reduce our deficit, I argued for a balanced, responsible approach, and part of that included making sure that the wealthiest Americans pay a little bit more. I think every voter out there understood that, that was an important debate, and the majority of voters agreed with me. Not -- by the way, more voters agreed with me on this issue than voted for me. So, we’ve got a clear majority of the American people who recognize, if we’re going to be serious about deficit reduction, we’ve got to do it in a balanced way. The only question now is are we going to hold the middle class hostage in order to go ahead and let that happen? Or, can we all step back and say, here’s something we agree on, we don’t want middle class taxes to go up. Let’s go ahead and lock that in. That will be good for the economy. It will be good for consumers. It will be good for businesses. It takes the edge off the fiscal cliff, and let’s also then commit ourselves to the broader package of deficit reduction that includes entitlement changes and it includes potentially tax reform as well as I’m willing to look at additional work we can do on the discretionary spending side. So, I want a -- big deal. I want a comprehensive deal. I want to see if we can, you know, at least for the foreseeable future, provide certainty to businesses and the American people so that we can focus on job growth, so that we’re also investing in the things that we need, but right now what I want to make sure is that the taxes on middle class families don’t go up, and there’s an easy way to do that. We could get that done by next week. Rory Montenegro (ph), Telemundo. QUESTION: Thank you, Mr. President. QUESTION: On immigration reform, the criticism in the past has been that you did not put forth legislation with specific ideas and send it up to the Hill. This time around, you have said again that this will be one of the top priorities for a second term. Will you, then, send legislation to the Hill? And exactly what do you envision is broad immigration reform? Does that include a legalization program? And also, what lessons, if any, did Democrats learn from this last election and the Latino vote? OBAMA: Well, I think what was incredibly encouraging was to see a significant increase in Latino turnout. This is the fastest-growing group in the country and, you know, historically what you’ve seen is Latino vote -- vote at lower rates than the broader population. And that’s beginning to change. You’re starting to see a sense of empowerment and civic participation that I think is going to be powerful and good for the country. And it is why I’m very confident that we can get immigration reform done. Before the election, I had given a couple of interviews where I predicted that Latino vote was going to be strong and that that would cause some reflection on the part of Republicans about their position on immigration reform. I think we’re starting to see that already. I think that’s a positive sign. This has not historically been a partisan issue. We’ve had President Bush and John McCain and others who have supported comprehensive immigration reform in the past. So, we need to seize the moment. And my expectation is that we get a bill introduced and we begin the process in Congress very soon after my inauguration. OBAMA: And, in fact, some conversations I think are already beginning to take place among senators and congressmen and my staff about what would this look like. And when I say comprehensive immigration reform, it’s very similar to the outlines of previous immigration reform. I think it should include a continuation of the strong border security measures that we’ve taken. Because we have to secure our border. I think it should contain serious penalties for companies that are purposely hiring undocumented workers and -- and taking advantage of them. And I do think that there should be a pathway for legal status for those who are living in this country, are not engaged in criminal activity, are here to -- simply to work. I’ve -- it’s important for them to pay back taxes. It’s important for them to learn English. It’s important for them to potentially pay a fine, but to give them the avenue whereby they can resolve their legal status here in this country, I think is very important. Obviously making sure that we put into law what -- the first step that we’ve taken administratively dealing with the DREAM Act kids is very important as well. The one thing that I’m -- I’m very clear about is that young people who are brought here through no fault of their own, who have gone to school here, pledged allegiance to our flag, want to serve in our military, want to go to school and contribute to our society, that they shouldn’t be under the cloud of deportation. That we should give them every opportunity to earn their citizenship. And so, you know there are other components to it, obviously. The business community continues to be concerned about getting enough high-skilled workers. And I am a believer that if you’ve got a PhD in physics, or computer science who wants to stay here, and start a business here, we shouldn’t make it harder for them to stay here, we should try to encourage him to contribute to this society. I think that the agricultural sector, obviously has very specific concerns about making sure that they’ve got a workforce that helps deliver food to our table. So there’re gonna be a bunch of components to it, but I think whatever process we have needs to make sure border security’s strong, needs to deal with employers effectively, needs to provide a pathway for the undocumented here, needs to deal with the DREAM Act kids. And I think that’s something that we can get done. Chuck Todd? Where’s Chuck? QUESTION: Mr. President, I just want to follow up on both Ben’s question and Jessica’s (ph) question. On having to do with Ben’s question... OBAMA: How about Laurie’s (ph) question, you want to follow up on that one too? (LAUGHTER) QUESTION: I -- I -- you know -- no, I feel like you answered that one completely. (LAUGHTER) Are you withholding judgment on whether you should have known sooner that there was a potential -- that there was an investigation into whether your CIA director -- potentially there was a national security breach with your CIA director? Do you believe you should have known sooner or are you withholding judgment until the investigation is complete on that front? And then the follow-up to Jessica’s (ph) question, tax rates. Are you -- is there no deal at the end of the year if tax rates for the top 2 percent aren’t the Clinton tax rates, period? No ifs, ands or buts and any room in negotiating on that specific aspect of the fiscal cliff? OBAMA: I am -- I am withholding judgment with respect to how the entire process surrounding General Petraeus came up. You know, we don’t have all the information yet. But I want to say that I have a lot of confidence generally in the FBI. And they’ve got a difficult job. And so I’m gonna wait and see to see if there’s any other... QUESTION: (OFF-MIKE) OBAMA: Well, I mean, Chuck, what I’ll say is that if -- it is also possible that had we been told, then you’d be sitting here asking a question about why were you interfering in a criminal investigation? So, you know, I -- I think it is best right now for us to just see how this whole process is unfolding. With respect to the tax rates, I -- I just want to emphasize, I am open to new ideas. If the Republican counterparts, or some Democrats, have a great idea for us to raise revenue, maintain progressivity, make sure the middle class isn’t getting hit, reduces our deficit, encourages growth, I’m not going to just slam the door in their face. I want to hear -- I want to hear ideas from everybody. QUESTION: (OFF-MIKE) red line. OBAMA: Well look, I believe this is solvable. I think that fair minded people can come to an agreement that does not cause the economy to go back into recession, that protects middle class families, that focuses on jobs and growth, and reduces our deficit. I’m confident it can be done. My budget frankly doesn’t. I understand that I don’t expect the Republicans simply to adopt my budget. That’s not realistic. So, I recognize we’re going to have to compromise. And, as I said on election night, compromise is hard. And not everybody gets 100 percent of what they want, and not everybody is going to be perfectly happy. But, what I will not do is to have a process that is vague, that says we’re gonna sort of, kind of raise revenue through dynamic scoring or closing loopholes that have not been identified. OBAMA: And the reason I won’t do that, is because I don’t want to find ourselves in the position, six months from now or a year from now, where low and behold, the only way to close the deficit is to sock it to middle-class families or to burden families that have disabled kids or, you know, have a parent in a nursing home, or suddenly we’ve got to cut more out of our basic research budget that is the key to growing the economy in the long term. So, that’s my concern. I’m less concerned about red lines per se. What I’m concerned about is not finding ourselves in a situation where the wealthy aren’t paying more or aren’t paying as much as they should. Middle-class families one way or another are making up the difference. That’s the kind of status quo that has been going on here too long, and that’s exactly what I argued against during this campaign. And if there’s one thing that I’m pretty confident about is the American people understood what they were getting when they gave me this incredible privilege of being in office for another four years. They want compromise. They want action. But they also want to make sure that middle-class folks aren’t bearing the entire burden and sacrifice when it comes to some of these big challenges. They expect that folks at the top are doing their fair share as well, and that’s going to be my guiding principle during these negotiations, but more importantly during the next four years of my administration. Nancy Cordes. QUESTION: Mr. President, on election night you said that you were looking forward to speaking with Governor Romney, sitting down in the coming weeks to discuss ways that you could work together on this nation’s problems. Have you extended that invitation? Has he accepted? And in what ways do you think you can work together? OBAMA: You know, we haven’t scheduled something yet. I think everybody forgets that the election was only a week ago. And I know I’ve forgotten. I forgot on Wednesday. (LAUGHTER) So I think everybody needs to catch their breath. I’m sure that Governor Romney is spending some time with his family. And my hope is before the end of the year, though, we have a chance to sit down and talk. You know, there -- there’re certain aspects of Governor Romney’s record and his ideas that I think could be very helpful. And, well, to give you one example, I do think he did a terrific job running the Olympics. And, you know, that skillset of trying to figure out how do we make something work better applies to the federal government. There are a lot of ideas that I don’t think are partisan ideas but are just smart ideas about how can we make the federal government more customer friendly, how can we make sure that, you know, we’re consolidating programs that are duplicative; you know, how can we eliminate additional waste. He presented some ideas during the course of the campaign that I actually agree with. And so it’d be interesting to talk to him about something like that. There may be ideas that he has with respect to jobs and growth that can help middle-class families that I want to hear. So, you know, I’m not either prejudging what he’s interested in doing nor am I suggesting I’ve got some specific assignment, but what I want to do is to -- is to get ideas from him and see if -- see if there’s some ways that we can potentially work together. QUESTION: But when it comes to your relationships with Congress, one of the most frequent criticisms we’ve heard over the past few years from members on both sides is that you haven’t done enough to reach out and build relationships. Are there concrete ways that you plan to approach your relationships with Congress in the second term? OBAMA: Look, I think there is no doubt that I can always do better. And so I will, you know, examine ways that I can make sure to communicate my desire to work with everybody, so long as it’s advancing the cause of strengthening our middle class, and improving our economy. You know, I’ve got a lot of good relationships with folks both in the House and the Senate. I have a lot of relationships on both sides of the aisle. It hasn’t always manifested itself in the kind of agreements that I’d like to see between Democrats and Republicans. And so, I think all of us have responsibilities to see if there are things that we can improve on, and I don’t exempt myself from needing to, you know, do some self reflection and see if I can improve our working relationship. There are probably going to be still some very sharp differences, and as I said during the campaign, there are going to be times where there are fights, and I think those are fights that need to be had, but what I think the American people don’t want to see is a focus on the next election, instead of a focus on them. And I don’t have another election. And, you know, Michelle and I were talking last night about, you know, what an incredible honor and privilege it is to -- to be put in this position. And there are people all across this country, millions of folks, who’ve worked so hard to help us get elected, but they’re also millions of people who may not have voted for us, but are also counting on us. OBAMA: And, you know, we take that responsibility very seriously. I take that responsibility very seriously. And I hope and intend to be an even better president in the second term, than I was in the first. Jonathan Karl? QUESTION: Thank you Mr. President. Senator John McCain, and Senator Lindsey Graham both said today that they want to have Watergate-style hearings on the attack on the U.S. consulate in Benghazi, and said that if you nominate Susan Rice to be secretary of State, they will do everything in their power to block her nomination. Senator Graham said, he simply doesn’t trust Ambassador Rice after what she said about Benghazi. I’d like your reaction to that? And -- and would those threats deter you from making a nomination like that? OBAMA: Well first of all I’m not going to comment on various nominations that I’ll put forward to fill out my cabinet for the second term. Those are things that are still being discussed. But let me say specifically about Susan Rice, she has done exemplary work. She has represented the United States and our interests in the United Nations with skill, and professionalism, and toughness, and grace. As I’ve said before, she made an appearance at the request of the White House in which she gave her best understanding of the intelligence that had been provided to her. OBAMA: If Senator McCain and Senator Graham, and others want to go after somebody? They should go after me. And I’m happy to have that discussion with them. But for them to go after the U.N. ambassador who had nothing to do with Benghazi? And was simply making a presentation based on intelligence that she had received? And to besmirch her reputation is outrageous. And, you know, we’re after an election now. I think it is important for us to find out exactly what happened in Benghazi and I’m happy to cooperate in any ways that Congress wants. We have provided every bit of information that we have and we will continue to provide information. And we’ve got a full-blown investigation, and all that information will be disgorged to Congress. And I don’t think there’s any debate in this country that when you have four Americans killed, that’s a problem. And we’ve got to get to the bottom of it and there needs to be accountability. We’ve got to bring those who carried it out to justice. They won’t get any debate from me on that. But when they go after the U.N. ambassador, apparently because they think she’s an easy target, then they’ve got a problem with me. And should I choose, if I think that she would be the best person to serve America in the capacity at the State Department, then I will nominate her. That’s not a determination that I’ve made yet. Ed Henry? QUESTION: I want to take Chuck’s lead and just ask a very small follow-up, which is whether you feel you have a mandate not just on taxes, but on a range of issues because of your decisive victory? But I want to stay on Benghazi, based on what John asked, because you said, “If they want to come after me, come after me.” I wanted to ask about the families of these four Americans who were killed. Sean Smith’s father, Ray, said he believes his won basically called 9-1-1 for help and they didn’t get it. And I know you’ve said you grieve for these four Americans; that it’s being investigated. But the families have been waiting for more than two months. QUESTION: So, I would like to -- for you to address the families, if you can. On 9/11, as commander in chief, did you issue any orders to try to protect their lives? OBAMA: Ed, you know, I’ll address the families not through the press. I’ll address the families directly, as I already have. And we will provide all the information that is available about what happened on that day. That’s what the investigation is for. But as I said repeatedly, if people don’t think that we did everything we can to make sure that we saved the lives of the folks who I sent there and who were carrying out missions on behalf of the United States, then you don’t know how our Defense Department thinks or our State Department thinks or our CIA thinks. Their number one priority is obviously to protect American lives. That’s what our job is. Now... QUESTION: (OFF-MIKE) OBAMA: ... Ed, we’re -- I’ll put forward -- I will put forward every bit of information that we have. I can can tell you that immediately upon finding out that our folks were in danger that my orders to my national security team were do whatever we need to do to make sure they’re safe. And that’s the same order that I would give anytime that I see Americans are in danger, whether they’re civilian or military, because that’s our number one priority. With respect to the issue of mandate, I’ve got one mandate: I’ve got a mandate to help middle-class families and families that have been working hard to try to get into the middle class. That’s my mandate. That’s what the American people said. They said, ‘Work really hard to help us. Don’t worry about the politics of it. Don’t worry about the party interests. Don’t worry about the special interests. Just work really hard to see if you can help us get ahead, because we’re working really hard out here and we’re still struggling, a lot of us. That’s my mandate. I don’t presume that because I won an election that everybody suddenly agrees with me on everything. I’m more than familiar with all the literature about presidential overreach in second terms. We are very cautious about that. On the other hand, I didn’t get re-elected just to bask in re- election. I got elected to do work on behalf of American families, and small businesses all across the country who are still recovering from a really bad recession, but are hopeful about the future. And I am too. The one thing that I said during the campaign, that maybe sounds like a bunch of campaign rhetoric, but now that the campaign is over I’m gonna repeat it, and hopefully you guys will believe me. When you travel around the country, you are inspired by the grit, and resilience, and hard work, and decency of the American people. And it just makes you want to work harder. You know, you meet families who are -- you know, have overcome really tough odds, and somehow are making it and sending their kids to college. And you meet young people who are doing incredible work in disadvantaged communities, because they believe in, you know, the American ideal, and it should be available for everybody. OBAMA: And, you meet farmers who are helping each other during times of drought, and, you know, you meet businesses that kept their doors open during the recession, even though the owner didn’t have to take a salary. And you -- when you talk to these folks, you say to yourself, “Man, they deserve a better government than they’ve been getting. They -- they deserve all of us here in Washington to be thinking every single day, how can I make things a little better for them? Which isn’t to say that everything we do is going to be perfect, or there aren’t just going to be some big, tough challenges that we have to grapple with. But I do know the federal government can make a difference. We’re seeing it right now on the Jersey coast and in New York. People are still going through a really tough time. The response hasn’t been perfect, but it’s been aggressive, and strong, and fast, and robust, and a lot of people have been helped because of it. And that’s a pretty good metaphor for how I want the federal government to operate generally, and I’m going to do everything I can to be sure it does. Christi Parsons? Hi. QUESTION: Thank you, Mr. President, and congratulations by the way. OBAMA: Thanks QUESTION: One quick follow up... OBAMA: She was there in -- when I was running for state Senate, so... QUESTION: That’s right, I was. OBAMA: ...Christi and I go back a ways. QUESTION: I’ve never seen you lose. (CROSSTALK) QUESTION: I wasn’t looking that one time. OBAMA: There you go. (LAUGHTER) QUESTION: One quick follow up, and then I want to ask you about Iran. I just want to make sure I understood what you said. Can you envision any scenario in which we do go off the fiscal cliff at the end of the year? And on Iran, are you preparing a final diplomatic push here to resolve the -- the nuclear program issue? And are we headed toward one-on-one talks? OBAMA: Well obviously, we can all imagine a scenario where we go off the fiscal -- fiscal cliff. If -- if despite the election, if despite the dangers of going over the fiscal cliff and -- and what that means for our economy, that there’s too much stubbornness in Congress that we can’t even agree on giving middle-class families a tax cut, then middle-class families are all going to end up having a big tax hike. And that’s going to be a pretty rude shock for them, and I suspect will have a big impact on the holiday shopping season, which in turn will have an impact on business planning and hiring and we can go back into a recession. It would be a bad thing. It is not necessary. So, I want to repeat. Step number one that we can take in the next couple of weeks, provide certainty to middle-class families, 98 percent of families who make less than $250,000 a year; 97 percent of small businesses; that their taxes will not go up a single dime next year. Give them that certainty right now. We can get that done. We can then set up a structure whereby we are dealing with tax reform, closing deductions, closing loopholes, simplifying, dealing with entitlements. And I’m ready and willing to make big commitments to make sure that we’re locking in the kind of deficit reductions that stabilize our deficit, start bringing it down, start bringing down our debt. I’m confident we can do it. It’s -- and, look, I’ve been living with this for a couple of years now. I know the math pretty well. And it’s -- it really is arithmetic. It’s not calculus. There are some tough things that have to be done, but there is a way of doing this that does not hurt middle-class families; that does not hurt our seniors; doesn’t hurt families with disabled kids; allows us to continue to invest in those things that make us grow like basic research and education, helping young people afford going to college. As we’ve already heard from some Republican commentators, a modest tax increase on the wealthy is not going to break their backs. They’ll still be wealthy. And it will not impinge on business investment. So -- so we know how to do this. This is just a matter of whether or not we come together and go ahead and say -- Democrats and Republicans, we’re both going to hold hands and do what’s right for the American people. And I hope that’s what happens. With respect to Iran, I -- I very much want to see a diplomatic resolution to the problem. I was very clear before the campaign, I was clear during the campaign, and I’m now clear after the campaign, we’re not gonna let Iran get a nuclear weapon. But I think there is still a window of time for us it resolve this diplomatically. We’ve imposed the toughest sanctions in history. It is having an impact on Iran’s economy. There should be a way in which they can enjoy peaceful nuclear power while still meeting their international obligations and providing clear assurances to the international community that they’re not pursuing a nuclear weapon. And so, yes, I -- I will try to make a push in the coming months to see if we can open up a dialogue between Iran and not just us, but the international community to see if we can get this thing resolved. I can’t promise that Iran will walk through the door that they need to walk through, but that would be very much the preferable option. QUESTION: (OFF-MIKE) OBAMA: I won’t talk about the details and negotiations, but I think it’s fair to say that we want to get this resolved and we’re not gonna be constrained by diplomatic niceties or protocols. If Iran is serious about wanting to resolve this, they’ll be in a position to resolve it. QUESTION: At one point, just prior to the election, there was talk that talks might be imminent... (CROSSTALK) OBAMA: That was not true and it’s not -- it’s not true as of today. OK. Just going to knock through a couple of others. Mark Landers (ph). Where’s Mark? There he is. Right in front of me. QUESTION: Thank you, Mr. President. In his endorsement of you a few weeks ago, Mayor Bloomberg said he was motivated by the belief that you would do more to confront the threat of climate change than your opponent. Tomorrow you’re going up to -- to New York City, where you’re going to, I assume, see people who are still suffering the effects of Hurricane Sandy, which many people say is further evidence of -- of how a -- a warming globe is changing our weather. What specifically do you plan to do in a second term to tackle the issue of climate change? And do you think the political will exists in Washington to pass legislation that could include some kind of attacks on carbon? OBAMA: You know -- as you know, Mark, we can’t attribute any particular weather event to climate change. What we do know is the temperature around the globe is increasing. Faster than was predicted even ten years ago. We do know that the Arctic ice cap is melting, faster than was predicted even five years ago. We do know that there have been extraordinarily -- there -- there have been an extraordinarily large number of severe weather events here in North America, but also around the globe. And I am a firm believer that climate change is real. That it is impacted by human behavior, and carbon emissions. And as a consequence, I think we’ve got an obligation to future generations to do something about it. Now, in my first term, we doubled fuel efficiency standards on cars and trucks. That will have an impact. That will take a lot of carbon out of the atmosphere. We doubled the production of clean energy, which promises to reduce the utilization of fossil fuels for power generation. And we continue to invest in potential breakthrough technologies that could further remove carbon from our atmosphere. But we haven’t done as much as we need to. So, what I’m going to be doing over the next several weeks -- next several months is having a conversation, a wide-ranging conversation with scientists, engineers, and elected officials to find out what can -- what more can we do to make short-term progress in reducing carbons, and then, you know, working through an education process that I think is necessary -- a discussion, a conversation across the country about, you know, what realistically can we do long term to make sure that this is not something we’re passing on to future generations that’s going to be very expensive and very painful to deal with. I don’t know what -- what either Democrats or Republicans are prepared to do at this point, because, you know, this is one of those issues that’s not just a partisan also. I also think there’s -- there are regional differences. There’s no doubt that for us to take on climate change in a serious way would involve making some tough political choices. And, you know, understandably, I think the American people right now have been so focused, and will continue to be focused on our economy and jobs and growth that, you know, if the message is somehow we’re going to ignore jobs and growth simply to address climate change, I don’t think anybody’s gonna go for that. I won’t go for that. If on the other hand we can shape an agenda that says we can create jobs, advance growth, and make a serious dent in climate change and be an international leader, I think that’s something that the American people would support. So, you know, you can expect that you’ll hear more from me in the coming months and years about how we can shape an agenda that garners bipartisan support and helps moves this -- moves this agenda forward. QUESTION: It sounds like you’re saying (OFF-MIKE) OBAMA: That -- that I’m pretty certain of. And, look, we’re -- we’re still trying to debate whether we can just make sure the middle- class families don’t get a tax hike. Let’s see if we can resolve that. That should be easy. This one’s hard. But it’s important because, you know, one of the things that we don’t always factor in are the costs involved in these natural disasters. We just put them off as -- as something that’s unconnected to our behavior right now. And I think what -- based on the evidence we’re seeing is that what we do now is gonna have an impact and a cost down the road if -- if we don’t do something about it. All right, last question. Mark Felsenthal? Where’s Mark? QUESTION: Thank you. Mr. President, the Assad regime is engage in a brutal crackdown on its people. France has recognized the opposition coalition. What would it take for the United States to do the same? And is there any point at which the United States would consider arming the rebels? OBAMA: You know, I was one of the first leaders, I think around the world, to say Assad had to go in response to the incredible brutality that his government displayed, in the face of what were initially peaceful protests. Obviously the situation has seriously deteriorated since then. We have been extensively engaged with the international community as well as regional powers to help the opposition. We have committed hundreds of millions of dollars to humanitarian aid to help folks both inside of Syria, and outside of Syria. We are constantly consulting with the opposition on how they can get organized so that they’re not splintered, and divided in the face of the onslaught from the Assad regime. We are in very close contact with countries like Turkey and Jordan that immediately border Syria, and obviously Israel which is having already grave concerns, as we do, about for example, movements of chemical weapons that might occur in such a chaotic atmosphere. And they could have an impact, not just within Syria, but on the region as a whole. I’m encouraged to see that the Syrian opposition created an umbrella group that may have more cohesion than they’ve had in the past. We’re going to be talking to them. My envoys are going to be traveling to, you know various meetings that are going to be taking place with the international community, and the opposition. We consider them a legitimate representative of the aspirations of the Syrian people. We’re not yet prepared to recognize them as some sort of government in exile, but we do think that it is a broad-based representative group. One of the questions that we’re going to continue to press is, making sure that that opposition is committed to a democratic Syria, an inclusive Syria, a moderate Syria. We have seen extremist elements insinuate themselves into the opposition. And, you know, one of the things that we have to be on guard about, particularly when we start talking about arming opposition figures, is that we’re not indirectly putting arms in the hands of folks who would do Americans harm, or do Israelis harm, or otherwise engage in -- in actions that are detrimental to our national security. So we’re -- we’re constantly probing, and working on that issue. The more engaged we are, the more we’ll be in a position to make sure that -- that we are encouraging the most moderate, thoughtful elements of the opposition that are committed to inclusion, observance of human rights, and working cooperatively with us over the long-term. Alright? Thank you very much. QUESTION: (OFF-MIKE) on spending, the $1.2 trillion figure, is that something you see in the short-term or is there... OBAMA: That was a great question, but it would be a horrible precedent for me to answer your question just because you yelled it out. So thank you very much, guys. END ||||| Photo by Jim Watson/AFP/Getty Images. President Obama speaks during a press conference at the White House on Wednesday, his first since he was re-elected As we're guessing you probably remember, President Obama defeated Mitt Romney in last week's election to earn himself another four years in the White House. But in case you or anyone else needed a reminder, the president offered up a few during this afternoon's press conference, his first since his re-election. (Emphasis ours.) In his opening remarks: "I won't pretend that figuring out everything else will be easy, but I'm confident we can do it and I know we have to. I know that that's what the American people want us to do. That was a very clear message from the election last week." On tax reform: "I think every voter out there understood that that was an important debate, and the majority of voters agreed with me, not -- by the way, more voters agreed with me on this issue than voted for me." On his relationship with Congress: "There are probably going to be still some very sharp differences. And as I said during the campaign, there are going to be times where there are fights. And I think those are fights that need to be had. But what I think the American people don't want to see is a focus on the next election instead of a focus on them. And I don't have another election." And then when asked directly about whether his electoral victory gives him a mandate: "I've got one mandate. I've got a mandate to help middle-class families and families that are working hard to try to get into the middle class. That's my mandate. That's what the American people said. They said, work really hard to help us. .. "I don't presume that because I won an election, that everybody suddenly agrees with me on any -- everything. I'm more than familiar with all the literature about presidential overreach in second terms. We are very cautious about that. "On the other hand, I didn't get re-elected just to bask in re-election. I got elected to do work on behalf of American families and small businesses all across the country who are still recovering from a really bad recession but are hopeful about the future. And -- and I am too." ||||| Mr. Obama’s stance appeared to leave room for the White House and Republicans to negotiate a tax rate somewhere in between and then raise additional revenue by restricting tax deductions and credits on high incomes. “I don’t expect Republicans simply to adopt my budget,” he said. “That’s not realistic. So I recognize that we’re going to have to compromise.” Still, Mr. Obama said he could envision a situation in which there was no agreement and all the tax cuts expired. Such an outcome would be a “rude shock” for middle-class people, he said, and could set off a recession. “It would be a bad thing,” he said. “It is not necessary.” By suggesting he was willing to accept failed negotiations, Mr. Obama was in part trying to give himself more leverage than in 2010, when fears about the economy and its impact on his political standing caused him to reverse course and accept an extension of all the Bush tax cuts in exchange for additional stimulus. This time, however, the economy is somewhat stronger, Mr. Obama has no more elections in front of him — as he pointed out on Wednesday — and the package of budget changes set to take effect on Jan. 1 includes both tax increases and military cuts that Republicans generally oppose. Speaker John A. Boehner, the effective leader of the Republican Party, said Republicans were not ready to accept Mr. Obama’s proposal because it would “hurt our economy and make job creation more difficult.” But he added that there was a “spirit of cooperation” that had infused Washington and that gave him optimism that some sort of deal would eventually come to pass. Republicans say they will find a way to raise enough money to reduce the deficit without lifting the top rates. Back-of-the-envelope math suggests that eliminating all tax breaks for the top 2 percent of households would raise about $2 trillion over 10 years, more than the $1.6 trillion that the White House demands, as part of a $3 trillion deficit-reduction package over 10 years. But having all of the additional tax revenue come from the restriction of tax breaks would require getting rid of virtually every such provision, like the home-mortgage deduction, in the tax code on top incomes. “The math tends not to work,” Mr. Obama said. Allowing tax rates to rise on the wealthy — to the Clinton-era levels, or a few percentage points below them — puts much more money on the table and would allow more moderate changes to deductions, Democrats argue. Looking beyond the immediate fiscal challenges, Mr. Obama expressed optimism about one major goal — immigration legislation — and caution about another, climate change. The president said he intended to pursue comprehensive immigration legislation, and noted that the election had prompted reflection among Republicans about their opposition to such an effort. Even as he criticized Mr. McCain on Benghazi, he cited his support for an overhaul of immigration law as an indication that it could pass. On climate change, Mr. Obama played down expectations for any major initiative. He spoke of holding a conversation with scientists and engineers about fresh ideas, but said more ambitious legislation would come only after the economy strengthened. “We’re still trying to debate whether we can just make sure that middle-class families don’t get a tax hike,” he said. “That should be easy. This one’s hard.” ||||| President Barack Obama said Wednesday he has seen no evidence that national security was threatened by the widening sex scandal that ensnared his former CIA director and top military commander in Afghanistan. President Barack Obama answers a question during a news conference in the East Room of the White House in Washington, Wednesday, Nov.14, 2012. (AP Photo/Charles Dharapak) (Associated Press) President Barack Obama steps up to the podium before a news conference in the East Room of the White House in Washington Wednesday, Nov. 14, 2012. (AP Photo/Charles Dharapak) (Associated Press) President Barack Obama makes an opening statement during a news conference in the East Room of the White House in Washington Wednesday, Nov. 14, 2012. (AP Photo/Charles Dharapak) (Associated Press) President Barack Obama makes an opening statement during his first news conference after Election Day, Wednesday, Nov. 14, 2012, in the East Room of the White House in Washington. (AP Photo/Charles Dharapak) (Associated Press) President Barack Obama answers a question during a news conference in the East Room of the White House in Washington, Wednesday, Nov. 14, 2012. (AP Photo/Charles Dharapak) (Associated Press) In his first postelection news conference, Obama also reaffirmed his belief that the U.S. can't afford to continue tax cuts for the wealthiest Americans, a key sticking point in negotiations with Republicans over the impending "fiscal cliff." He said, "The American people understood what they were getting" when they voted for him after a campaign that focused heavily on taxes. And he defiantly told critics of U.N. Ambassador Susan Rice, a potential candidate to lead the State Department, that they should "go after me" _ not her _ if they have issues with the administration's handling of the deadly attacks on Americans in Benghazi, Libya. His words were aimed at Republican Sens. John McCain and Lindsey Graham, who have vowed to block Rice's potential nomination. The tangled email scandal that cost David Petraeus his CIA career and led to an investigation of Gen. John Allen has disrupted Obama's plans to keep a narrow focus on the economy coming out of last week's election. And it has overshadowed his efforts to build support behind his re-election pledge to make the wealthy pay more in taxes in order to reduce the federal deficit. Obama said he hoped the scandal would be a "single side note" in Petraeus' otherwise extraordinary career. Petraeus resigned as head of the CIA last Friday because of an extramarital affair with his biographer, Paula Broadwell, who U.S. officials say sent harassing emails to a woman she viewed as a rival for the former general's affection. The investigation revealed that that woman, Jill Kelley, also exchanged sometimes-flirtatious messages with Allen. Obama brushed aside questions about whether he was informed about the FBI investigations that led to the disclosures quickly enough. White House officials first learned about the investigations last Wednesday, the day after the election, and Obama was alerted the following day. "My expectation is that they follow the protocols that they've already established," Obama said. "One of the challenges here is that we're not supposed to meddle in criminal investigations and that's been our practice." Turning back to the economy, the president vowed not to cave to Republicans who have pressed for tax cuts first passed by George W. Bush to be extended for all income earners. Obama has long opposed extending the cuts for families making more than $250,000 a year, but he gave into GOP demands in 2010 when the cuts were up for renewal. That won't happen this time around, he said Wednesday. "Two years ago the economy was in a different situation," Obama said. "But what I said at the time was what I meant. Which was this is a one-time proposition." The president and Congress are also seeking to avoid across-the-board spending cuts scheduled to take effect because lawmakers failed to reach a deal to reduce the federal deficit. Failure to act would lead to spending cuts and higher taxes on all Americans, with middle-income families paying an average of about $2,000 more next year, according to the nonpartisan Tax Policy Center. Obama said he was "open to new ideas" but would not allow current tax rates to continue for the top 2 percent of wage earners, drawing a line for Republicans who say they will not tolerate any tax rate increases. Asked if the tax rates for the rich had to return to Clinton-era levels, Obama indicated he was open to negotiations. On another topic, Obama said it was his "expectation" that a comprehensive immigration reform bill would be introduced "very soon after my inauguration." His support among Hispanics was one of his keys to victory over Republican rival Mitt Romney, who staked out conservative positions on immigration changes during the GOP primaries. Obama failed to make progress on comprehensive immigration changes during his first term but said he planned to "seize the moment" after his inauguration. The White House is already engaged in conversations with Capitol Hill. Obama said the legislation should make permanent the administrative changes he made earlier this year that allow some young illegal immigrants to remain in the country legally. He said that the overall bill should include a "pathway to legal status" for the millions of immigrants who are in the U.S. illegally but and haven't committed crimes unrelated to immigration. Before tackling immigration, Obama will have to face the departure of several key Cabinet secretaries and White House staffers. Among those expected to leave are Treasury Secretary Timothy Geithner and Secretary of State Hillary Rodham Clinton. Rice, the U.S. ambassador to the United Nations, and Massachusetts Sen. John Kerry are the leading candidates to replace Clinton. Rice is a favorite of the president, but she has faced intense criticism for her role in the initial administration response to the deaths of four Americans, including the U.S. ambassador to Libya, during an attack "When they go after the U.N. ambassador, apparently because they think she's an easy target, then they've got a problem with me," Obama said. "And should I choose, if I think that she would be the best person to serve America, in the capacity of the State Department, then I will nominate her. That's not a determination that I've made yet."

– President Obama has wrapped up his first press conference since the election, with, surprise, surprise, the David Petraeus scandal and the fiscal cliff at the top of the agenda, reports the AP. But he also made headlines with a strong defense of UN ambassador Susan Rice. The full transcript is here. Some highlights: Petraeus: Obama again praised the general for his "extraordinary career" but said Petraeus fell short of his own personal standards. Asked whether classified information had leaked, Obama said he was not aware of any and deferred to the ongoing FBI investigation. “I have no evidence at this point from what I’ve seen that classified information was disclosed that would have in any way have had an impact on our national security.” Fiscal cliff: He reiterated that he is "open to compromise" but again insisted that tax cuts should not be extended for those making more than $250,000 a year. At the same time, he wants Congress to immediately pass a bill extending the cuts for those who make less. “We should not hold the middle class hostage while we debate tax cuts on the wealthy,” he said, declaring that he had a "mandate" on the issue, notes Slate. Later, of the looming deadline: "I believe this is solvable. Benghazi: "If people don't think that we did everything" we could to protect Americans, then they don't understand how the Pentagon, the CIA, or the State Department operates, said Obama, who promised to turn over all information from the follow-up investigations. Susan Rice: He also issued a strong defense of his UN ambassador (and secretary of state contender), who has come under Republican criticism for her initial public response to the Benghazi attack. If John McCain "and others want to go after somebody, they should go after me," he said. “I don’t think there’s any debate in this country that when you have four Americans killed that’s a problem. ... But when they go after the UN ambassador, apparently because they think she’s an easy target, then they’ve got a problem with me.” Climate change: Obama said his administration didn't do enough in his first term and pledged to start a "national conversation" in his second. Immigration reform: He said work on legislation should start immediately, adding that the heavy Latino turnout in the election should "cause some reflection on the part of Republicans," reports the New York Times. Mitt Romney: He said he hasn't reached out to Romney yet but hopes to meet with him before the end of the year. Syria: Obama said he was among the first world leaders to call for Bashar al-Assad to go, but he didn't follow France's lead of recognizing the new rebel coalition. “One of the things we have to be on guard about, particularly when we start talking about arming the opposition, is that we’re not putting arms in the hands of people who would do Americans harm, or do Israelis harm.”

notch signalling is an evolutionarily conserved signalling pathway , which plays a significant role in a wide array of cellular processes including proliferation , differentiation , and apoptosis . in humans classic notch signalling consists of four notch receptors ( notch 1 , 2 , 3 , and 4 ) and their ligands ( delta - like 1 , 3 , and 4 and jagged 1 and 2 ) . all receptors are synthesised as a precursor form consisting of extracellular , transmembrane , and intracellular subunits . within the golgi apparatus , one of them contains most of the extracellular domain , and the second is composed of the rest of the extracellular and transmembrane domains . it should be mentioned that extracellular domain of the notch receptor is composed of 36 egf - like repeats . in the most widely accepted model of notch activation ( fig . 1 ) ligand binding to egf - like repeats unfolds the negative regulatory region ( nrr ) admitting the second cleavage through metalloproteinases of the adam family . after this , -secretase complex performs an intramembrane cleavage releasing the notch intracellular domain ( notchic or nicd ) that translocates to the nucleus . importantly , for activation of notch pathway the mastermind - like family of proteins ( maml 1/2/3 ) are also needed because they form a ternary complex with cbf1-notchic . then , this complex composed of cbf1-notchic - maml acts as a transcriptional activator leading to notch target gene transcription . among the primary targets there are genes belonging to the basic helix - loop - helix ( bhlh ) family . following notch activation , the hairy / enhancer - of - split ( he s ) family and the hairy - related transcription factor ( hrt ) are expressed . notch signalling pathway nevertheless , it must be noted that notch is a binary cell fate determinant , and its overexpression has been described as oncogenic in a broad range of human malignancies [ 4 , 5 ] . this finding led to interest in therapeutically targeting this pathway especially by the use of -secretase inhibitors ( gsis ) , which block the cleavage of notch at the cell membrane by inhibition of notchic release . preclinical cancer models have clearly demonstrated that gsis suppress the growth of such malignancies as pancreatic , breast , and lung cancer ; however , gsi treatment in vivo is associated with significant side effects . in this paper , we review the role of notch signalling as an oncogenic factor involved in cancer development and the same the promising therapeutic target for gsis activity . emerging evidence indicates that notch effects are dependent on the cellular context in which it is activated ( table 1 ) . the oncogenic potential of the notch pathway was first described in acute t - cell lymphoblastic leukaemia ( t - all ) in the late 1980s . in recent years , reedijk et al . revealed that high levels of jag1 and notch1 have been connected with poorer overall survival ( os ) of breast cancer patients ( p = 0.01 ) . it is also worth noting that a synergistic effect of these proteins on os has been revealed as well ( p = 0.003 ) . another study demonstrated that jag1 mrna has been associated with expression of basal breast cancer markers such as cytokeratin 5 and with reduced disease - free survival ( dfs ) throughout the follow - up period ( p = 0.034 ) . it has also been correlated with tumour size , oestrogen receptor status ( er ) , and progesterone receptor status ( pgr ) negativity , high tumour grade , and p53 reactivity . moreover , tumours with high levels of both mrna and protein demonstrated more reduced dfs in comparison to all other groups ( p = 0.020 ) . found that jag1 promoted cyclin d1-mediated proliferation in the case of triple - negative breast cancers because its down - regulation was connected with inhibition of cyclin d1 expression and the same inhibition of cell cycle through the cyclin d1-dependent g1/s checkpoint . interesting results have been obtained by simon et al . , who showed that knockdown of jag1 in mouse adrenocortical cancer cells resulted in density- dependent inhibition of cell proliferation . co - culture experiments of normal y1 cells with jag1 kd or control ( scramble ) cells lines demonstrated that jag1kd cells were able to proliferate due to sufficient jag1 signalling from adjacent cells , whereas cells receiving diminished jag1 inputs from jag1kd cells did not proliferate . it has been also detected in the case of cells receiving inputs from scramble cells . therefore , it might be said that jag1 does not have a cell - autonomous effect but instead mediates cancer cell proliferation through binding to and activating notch receptors on cells localised in the close vicinity . for example , the active component of the notch1 pathway is commonly expressed in ovarian papillary serous adenocarcinoma . depletion of notchic by notch1 sirna significantly inhibited growth of such cancer cell lines as caov3 , ovcar3 , and skov3 in comparison to transfection with non - specific sirna . its expression enhanced gradually with the poor differentiating and increasing figo stage in ovarian cancer . in general , the figo system includes five stages . invasion of surrounding organs and tissues is related to stage ii of the figo system . the spread to the distant nodes is a feature of stage iii whereas distant metastasis is linked to stage iv [ 14 , 15 ] . for example , notch3 was shown to be overexpressed in the cytoplasm and nucleus of pancreatic cancer cells . there were also correlations between expression of notch3 and such components of intracellular signalling pathways as pakt , stat3 , and pstat3 . this relation between overexpression of signalling molecules and poor clinical outcome may be interesting in light of findings linking notch signalling , epigenetic silencing , and control of cell cycle during cancerogenesis . mullendore et al . revealed that pancreatic cancer cell lines are characterised by overexpression of notch ligand transcripts such as jag2 and dll4 in comparison to htert- hpne cells , with the majority having > 50-fold relative expression levels . in some cells , the genomic amplification of dll3 locus has also been observed , mirrored by overexpression of dll3 transcripts . interestingly , knockdown of dll3 by rnai was clearly connected with suppression of anchorage - independent growth in the su86.86 cell line . notch signalling overexpression and its role in cancer development the aberrant notch signalling has been involved in the emt induction during which cancer cells acquire an invasive phenotype . this may be linked with overexpression of jag1 , notch1 , and consequently overexpression of snail factors , which are known to be correlated with poor prognosis in many human cancers . in this context it is worth noting study of wang et al . , who revealed that gemcitabine - resistant ( gr ) pancreatic cancer cells showed enhanced activation of jag1 and notch2 at the level of mrna and protein . the gr cells transfected with notch2 and jag1 sirna showed increased expression of e - cadherin and reduced expression of vimentin and zeb1 . in such cases , expression of snail1 and snail2 have also been down - regulated . these results suggest that activation of notch components could mediate the induction of emt phenotype . in contrast , down - regulation of this signalling may act as a promising factor responsible for emt inversion . what is important , down - regulation of notch2 and jagged1 by sirna transfection resulted in decreased nf-b in gr cells , indicating the existence of molecular cross - talk between notch and nf-b . for example , upregulation of dll4 clearly promoted proliferation , migration , and invasion of sgc7901 gastric cancer cells in vitro and tumour growth in vivo . moreover , it was also responsible for decreased activity of mmp-9 ; however , its increased expression at the level of mrna has not been detected . probably , notch target genes , as well as mmp-9 , need post - transcriptional regulations . it is also possible that activation of mmp-9 can be suppressed by other signalling pathways or molecules activated by dll4 , e.g. tissue inhibitor of metalloproteinase-1 ( timp-1 ) , timp-2 , or other timps . it is also worth noting that in gastric cancer cells with overexpression of dll4 , increased level of mrna and secretion of mmp-2 proenzymes have been observed . probably mmp-9 signalling is not sufficient to exert an effect alone in gastric cancer progression , while other molecules such as mmp-2 play a more fundamental role . as revealed by yeasmin et al . in contrast to cervical tissue without any pathological changes and cervical intraepithelial neoplasia , squamous cell carcinomas displayed high levels of nuclear notch3 expression , which was associated with a shorter os of such patients . importantly , inactivation of notch3 diminished cell proliferation and induced apoptosis in me180 and skgiiib cell lines with notch3 overexpression . notch1 activation may drive the vertical growth phase ( vgp ) of primary melanoma toward a more aggressive phenotype . constitutive activation of notch1 by ectopic expression of notchic was probably responsible for proliferative abilities of vgp primary melanoma cells in a serum - independent and growth factor - independent manner in vitro . these effects were probably mediated by activation of the mitogen - activated protein kinase ( mapk ) and akt pathways because inhibition of mapk or the phosphatidylinositol 3-kinase ( pi3k ) akt pathway can reverse the tumour cell growth induced by notch1 . demonstrated that notch1 influenced melanoma development in a xenograft model by guarding cells from death . probably due to enhanced bax / bcl - xl ratio , which in turn may be responsible for induction of caspase-3 because notch1 has been shown to positively regulate bcl - xl expression in t cells and pancreatic cancer cells , which may be responsible for resistance to apoptosis [ 25 , 26 ] . another interesting finding is associated with the observation that notch1 knockdown significantly decreased cell growth due to inhibition of cyclin d1 . these findings imply that inhibition of cell and tumour growth can also be dependent on reduced cyclin d1 expression . notch1 may promote melanoma progression by inducing -catenin , which in turn regulate cyclin d1 expression . nevertheless , in this system -catenin appeared unaffected by inhibition of notch1 , which suggests that expression of cyclin d1 is under direct control of notch1 activity . proteolytic processing of notch by -secretase is a necessary step in the activation of this family of proteins . therefore , -secretase protease complex has been considered as a promising target for notch inhibition with a class of compounds called -secretase inhibitors ( gsis ) . all gsis that impair notch pathway act through its inhibition , despite their different chemical structures [ 29 , 30 ] . liu et al . compared the expression of notch components in a549 cancer cells after dapt ( gsi - ix ) and cisplatin ( cddp ) treatment . for example , some cells that display cd133 surface marker have been found in g2/m phase , and there were half as many cells in s phase in comparison to cd133 negative cells . but the most important fact was associated with the observation that inhibitory effects of cdpp were enhanced when cells had been pretreated with gsi . pharmacological blockade of notch by the use of gsis clearly reduced the percentage of cells displaying stem cell markers . in the case of glioblastoma , cells expressing cd133 did not show the ability to form colonies in vitro or engraft in vivo . revealed that treatment of colon cancer cells with mrk-003 reduced oxaliplatin - induced apoptotic cell death , while gsi treatment alone did not influence growth or apoptosis . interestingly , blocking of mcl-1 and bcl - xl by sirna or the small molecule inhibitor obatoclax restored the also , palagni et al . revealed that dual treatment with gsi ix and ag490 clearly altered apoptosis of pancreatic ductal adenocarcinoma cells ( pdac ) . moreover , proliferation , migration , and invasion of cells have also been impaired in comparison to monotherapy . it must be noted that combination treatment significantly attenuates tumour progression in vivo and inhibits transition from acinar - ductal - metaplasia to pdac . demonstrated that pretreatment of ovarian cancer cells with dapt and then with cisplatin increased apoptosis via modulation of such genes as cyclin b1 , bcl-2 , and caspase-3 . inhibition of notch1 with sulphonamide gsi ( gsi34 ) blunted hes1 activation in the case of colon cancer cells . after gsi34 treatment , cells showed sensitivity to chemotherapy , and this effect was synergistic with oxaliplatin , 5-fu , and sn-38 . nevertheless , administration of gsis in vivo is associated with strong side effects , especially within the gastrointestinal tract . in c57bl/6 and tgcrnd8 app transgenic mice , chronic administration of gsi ly-411575 was responsible for alterations in intestinal architecture , including increased goblet cell number and mucin secretion leading to epithelial erosion . moreover , reduced overall thymic cellularity and altered intrathymic differentiation at the cd4cd8cd44cd25 precursor stage has been observed as well . it is not surprising because hadland et al . revealed that application of gsi to foetal thymus organ cultures interferes with t cell development in a manner consistent with reduction of notch1 activity . it means that progression from an immature cd4/cd8 state to an intermediate cd4/cd8 double - positive state has been inhibited . importantly , all of these effects are consistent with the role of notch signalling as a crucial factor responsible for developmental processes and tissue homeostasis maintaining . although intensive studies are associated with the role of -secretase in pathological states it should be pointed out that this complex influences the proteolytic cleavages of around 55 membrane proteins [ 39 , 40 ] . therefore , it is clear that gsi are highly non - specific , and additional drugs must be designed which will more specifically target notch . the majority of the trials associated with the use of gsis in the cancer treatment are either at a stage at which it is too early to report the side effects or have been completed but these effects have not yet been published . krop et al . showed that inhibition of notch signalling has been detected with the 1.800 - 4.200 mg weekly dose levels of mk-0752 . among the most significant side effects the following should be mentioned : diarrhoea , nausea , vomiting , and fatigue . in this context , it is worth noting the study of tolcher et al . , who observed such effects as fatigue , thrombocytopenia , fever , rash , chills , and anorexia . in this context it is worth noting about transient grade 3 hypophosphataemia ( dose - limiting toxicity , one patient ) and grade 3 pruritus ( two patients ) , which have been reported at 27 mg and 60 mg of ro4929097 . ro4929097 can also be safely combined with temsirolimus in patients with metastatic high - grade synovial sarcoma and in patients with metastatic gastrointestinal stromal tumours . the rp2d was established at 20 mg of ro4929097 in combination with 37.5 mg of temsirolimus . in this case , the most common toxicities included fatigue , mucositis , neutropaenia , anaemia and hypertriglyceridaemia . in patients with refractory metastatic colorectal cancer after ro4929097 administration , no radiographic responses have been detected , and time to progression was short . moreover , immunohistochemical analysis of cancer tissue demonstrated positive staining for the notch receptors and notchic . interestingly , the positive staining was also visible in the case of hes1 protein . in summary , a great number of studies suggest a potential clinical application of gsis in cancer therapeutics . nevertheless , among major challenges on the way toward this goal one associated with gastrointestinal toxicity is very significant . moreover , notch is described to widely participate in cellular physiology , e.g. haematopoiesis and maintenance of arterial smooth muscle . so it is not surprising that inactivation of -secretase may result in vital organ dysfunction . second , it is worth noting that gsis do not exclusively target the notch pathway because -secretase has many substrates including erbb4 , cd44 , and syndecan-3 . gsis may also target proteases other than -secretase , and therefore these compounds may be responsible for adverse effects in vivo . it seems that partial inhibition of -secretase will be sufficient to inhibit notch components in cancer cells whereas the dosage will not affect the functions in tissue without lesions .

notch signalling is an evolutionarily conserved signalling pathway , which plays a significant role in a wide array of cellular processes including proliferation , differentiation , and apoptosis . nevertheless , it must be noted that notch is a binary cell fate determinant , and its overexpression has been described as oncogenic in a broad range of human malignancies . this finding led to interest in therapeutically targeting this pathway especially by the use of gsis , which block the cleavage of notch at the cell membrane and inhibit release of the transcriptionally active notchic subunit . preclinical cancer models have clearly demonstrated that gsis suppress the growth of such malignancies as pancreatic , breast , and lung cancer ; however , gsi treatment in vivo is associated with side effects , especially those within the gastrointestinal tract . although intensive studies are associated with the role of -secretase in pathological states , it should be pointed out that this complex impacts on proteolytic cleavages of around 55 membrane proteins . therefore , it is clear that gsis are highly non - specific and additional drugs must be designed , which will more specifically target components of the notch signalling .

@xmath2due to their large masses , heavy flavor quarks are believed to be unique probes to the strongly coupled qcd matter created in high energy @xmath0 collisions at the relativistic heavy ion collider ( rhic ) . they are mainly produced in the initial hard scatterings , so the production can be well studied by perturbative - qcd(pqcd ) @xcite . when heavy flavor quarks traverse the qcd medium , they are expected to lose less energy than light flavor quarks due to the dead - cone effect @xcite , if the dominant energy loss process is gluon radiation . however , recent experimental studies found that the productions of non - photonic electrons ( npe ) from the semi - leptonic decays of charm and bottom hadrons are strongly suppressed at high @xmath3 in central @xmath0 collisions relative to that in @xmath4 collisions scaled by the number of binary collisions @xcite and the npe - hadron azimuthal correlations possibly show a broadening on the away side @xcite . these results suggest some significant contributions from other processes to heavy flavor quark energy loss , which have been simulating various theoretical reconsiderations . @xmath2 in order to differentiate model calculations , high precision measurements of npe production in both @xmath0 and @xmath4 collisions , with disentangled charm and bottom contributions , are wanted . in addition , model calculations with correct dynamics should be able to predict the elliptic flow of heavy flavor quarks at the same time . simultaneous measurements of npe production suppression and elliptic flow have better discriminating power on energy loss dynamics than individual measurement alone . the star collaboration has recently measured the npe production with high precision @xcite and has separated charm and bottom contributions @xcite , in @xmath4 collisions . in these proceedings , we report the progresses of studying npe production and elliptic flow in @xmath0 collisions . we also report preliminary results of npe - hadron correlation , which bear the information of the processes of heavy flavor quarks traversing the bulk qcd medium and thus shed light on heavy flavor jet - medium interactions . @xmath2the data sets used here are @xmath0 collisions at @xmath1gev collected by the star detector during rhic run 2010 . in these proceedings , we have utilized about 40 million minimum bias triggered events and about 60 million high - tower triggered events . the most important detectors used for npe analyses are the tpc ( time projection chamber ) @xcite and the barrel calorimeter system @xcite including bemc ( barrel electromagnetic calorimeter ) and bsmd ( barrel shower maximum detector ) . in both data sets , electron identification procedures are applied , including , for example , analyzing the shower profiles in bsmd and the energy ( in bemc ) over momentum ( in tpc ) ratios . the calorimeter system largely enhances our ability to identify the electrons but currently constrains the electron kinematic to be @xmath5 gev / c and @xmath6 . the selected electron sample , inclusive electrons , is composed of mainly npes , photonic electrons and some hadron contamination . we reconstruct the 2d invariant masses of electron pairs to estimate the contribution of photonic electrons ( pe ) , the electrons from gamma conversions and @xmath7 , @xmath8 dalitz decays , with reconstruction efficiency @xmath9 obtained from simulation tracks embedded into real events , which spans @xmath10 depending on the cuts and the electron @xmath3 ( @xcite has more details on the analysis methods ) . then , statistically we have:@xmath11 where @xmath12 is the azimuthal correlation , but it also could be other npe variables , e.g. production or @xmath13 , and the hadron contribution is neglected if there are no more than 1% hadrons in the inclusive electron sample . @xmath2figure [ fig : spectra ] shows npe production studies in @xmath14 central @xmath0 collisions based on minimum bias triggered events . the left panel demonstrates that the non - photonic electron over photonic electron ratio in run 2010 is around 1 , much higher than previous @xmath0 runs , providing a cleaner environment for npe studies . the right panel shows the npe spectrum with @xmath3 from 2 gev / c to about 6 gev / c . for higher @xmath3 , high - tower triggered events will provide larger statistics , ensuring high precision in extended @xmath3 range . in this preliminary result , npe includes electrons from both open heavy flavor hadrons and heavy quarkonia . in our final results , we will subtract the latter . @xmath2 in figure [ fig : v2 ] , the elliptic flow ( @xmath15 ) studies , also based on minimum bias triggered events , are shown . we extract @xmath15 by fitting electron angular correlations with the event plane ( ep ) @xcite . as an example , the @xmath16 distribution in @xmath17 central @xmath0 collisions for npe with @xmath18 gev / c is shown in the left panel . in this middle centrality , the npe @xmath15 is finite and consistent with our previous study based on run 2007 @xcite , indicating possible coupling between heavy flavor quarks and the qcd medium . further conclusions may be drawn only after the statistics error bars get reduced enough as we analyze more statistics . the current systematic uncertainties mainly come from the ep resolution uncertainty due to large centrality bin size and from photonic electron reconstruction efficiency . the differences between different @xmath15 methods are yet to be studied and included . the right panel shows npe @xmath15 in different centrality bins . @xmath2 in order to ensure that npe represent well the directions of the parent charm and bottom quarks , we use npe with @xmath19 gev / c from high - tower events to study the npe - hadron correlation . when we use associated tracks with @xmath20 gev / c , the tracks that can present the bulk medium the best , the statistical uncertainties are large . with @xmath21 gev / c , we found there is a npe - hadron correlation beyond statistical uncertainties on both the near side and away side in @xmath17 central @xmath0 collisions , as shown in figure 3 in @xcite . if this correlation is also beyond the systematic uncertainties , mainly due to flow modulations which are still under study , then it would indicate heavy flavor tagged jets do interact with the qcd medium . nevertheless , quantitative measurements yet to emerge and theoretical considerations , such as in @xcite , are required to understand the physical picture . @xmath2 in summary , different measurements are sensitive to different aspects of the heavy flavor quark - medium interactions . the centrality dependence of these measurements will reflect properties of the qcd medium and together they provide strong constrains on dynamical models .

we present preliminary results of non - photonic electron ( npe ) production , npe - hadron azimuthal correlation as well as npe elliptic flow studies at midrapidity using a data set with high statistics and low photon conversion background from @xmath0 collisions at @xmath1 gev collected at rhic in run 2010 . @xmath2keywords : heavy flavor , heavy ion , energy loss , elliptic flow @xmath2classification : 1320.fc , 13.20.he , 25.75.cj @xmath2department of physics and astronomy , university of california , los angeles , california 90095 , usa @[email protected]

SECTION 1. SHORT TITLE. This Act may be cited as the ``Homeowners Insurance and Mitigation Assistance Act of 2008''. SEC. 2. NONREFUNDABLE PERSONAL CREDIT FOR CERTAIN HOMEOWNERS INSURANCE PREMIUMS. (a) In General.--Subpart A of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after section 25D the following new section: ``SEC. 25E. CERTAIN HOMEOWNERS INSURANCE PREMIUMS. ``(a) Allowance of Credit.--In the case of an eligible individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to 50 percent of the taxpayer's qualified homeowners insurance premium for such taxable year. ``(b) Limitations.-- ``(1) Maximum credit.--The credit allowed under subsection (a) for any taxable year shall not exceed $500. ``(2) Limitation based on adjusted gross income.--The amount of the credit allowable under subsection (a) shall be reduced (but not below zero) by 2 percentage points for each percentage point (or fraction thereof) by which the taxpayer's adjusted gross income exceeds the State median income for such a taxpayer for the preceding taxable year in the State in which the principal residence of such taxpayer is located. ``(3) Limitation based on amount of tax.--In the case of a taxable year to which section 26(a)(2) does not apply, the credit allowed under subsection (a) for any taxable year shall not exceed the excess of-- ``(A) the sum of the regular tax liability (as defined in section 26(b)) plus the tax imposed by section 55, over ``(B) the sum of the credits allowable under this subpart (other than this section and sections 23, 24, and 25B) and section 27 for the taxable year. ``(c) Eligible Individual.--For purposes of this section-- ``(1) In general.--The term `eligible individual' means any taxpayer whose principal residence is-- ``(A) substantially the same dwelling unit during the applicable period, and ``(B) located in either-- ``(i) an area determined by the President to warrant individual or individual and public assistance from the Federal Government under the Robert T. Stafford Disaster Relief and Emergency Assistance Act by reason of one or more hurricanes during 2004 or 2005, or ``(ii) a county-- ``(I) located in a State which borders the Atlantic Ocean or the Gulf of Mexico, and ``(II) which is determined by the Secretary, in consultation with the National Association of Insurance Commissioners, to have experienced a higher than average increase in homeowners insurance premiums during 2004, 2005, 2006, or 2007 due to hurricane risk. ``(2) Applicable period.--The term `applicable period' means-- ``(A) in the case of an area described in paragraph (1)(B)(i), the period beginning the day before the determination described in such paragraph and ending on the last day of the taxable year, and ``(B) in the case of an area described in paragraph (1)(B)(ii), the period beginning on September 1, 2005, and ending before the last day of the taxable year. ``(d) Qualified Homeowners Insurance Premium.--For purposes of this section-- ``(1) In general.--The term `qualified homeowners insurance premium' for any taxable year means an amount equal to the qualifying percentage of the eligible individual's homeowners insurance premium in effect on the first policy anniversary date (or, if greater, the second policy anniversary date) following the beginning of such individual's applicable period. ``(2) Qualifying percentage.--The term `qualifying percentage' is equal to the excess (expressed in percentage points) of-- ``(A) the eligible individual's percentage increase in homeowners insurance premium between the last policy anniversary before the beginning of such individual's applicable period and the policy anniversary date (as determined under paragraph (1)) following the beginning of such individual's applicable period, over ``(B) the national average percentage increase in homeowners insurance premiums between the same dates as determined by the Secretary, in consultation with the National Association of Insurance Commissioners. ``(e) Other Definitions.--For purposes of this section-- ``(1) Principal residence.--The term `principal residence' has the same meaning as when used in section 121. ``(2) Homeowners insurance.--The term `homeowners insurance' means any insurance covering a principal residence. ``(f) Termination.--This section shall not apply to taxable years beginning after December 31, 2009.''. (b) Conforming Amendment.--The table of sections for subpart A of part IV of subchapter A of chapter 1 of such Code is amended by inserting after the item relating to section 25D the following new item: ``Sec. 25E. Certain homeowners insurance premiums.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2008. SEC. 3. NONREFUNDABLE PERSONAL CREDIT FOR HURRICANE, EARTHQUAKE, AND TORNADO MITIGATION PROPERTY. (a) In General.--Subpart A of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after section 25E, as amended by section 2, the following new section: ``SEC. 25F. HURRICANE, EARTHQUAKE, AND TORNADO MITIGATION PROPERTY. ``(a) Allowance of Credit.--In the case of an individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to 25 percent of the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during such taxable year. ``(b) Maximum Credit.--The credit allowed under subsection (a) for any taxable year shall not exceed $5,000. ``(c) Qualified Hurricane, Earthquake, and Tornado Mitigation Expenditure.--For purposes of this section-- ``(1) In general.--The term `qualified hurricane, earthquake, and tornado mitigation property expenditure' means an expenditure for property-- ``(A) to improve the strength of a roof deck attachment, ``(B) to create a secondary water barrier to prevent water intrusion, ``(C) to improve the durability of a roof covering, ``(D) to brace gable-end walls, ``(E) to reinforce the connection between a roof and supporting wall, ``(F) to protect openings from penetration by windborne debris or by wind-driven rain, or ``(G) to protect exterior doors and garages, in a qualified dwelling unit located in a qualified State and owned by the taxpayer. ``(2) Qualified dwelling unit.--The term `qualified dwelling unit' means a dwelling unit that is assessed at a value that is less than $1,000,000 by the locality in which such dwelling unit is located and with respect to the taxable year for which the credit described in subsection (a) is allowed. ``(3) Qualified state.--The term `qualified State' means Alabama, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, or Virginia. ``(d) Limitation.--An expenditure shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year only if the onsite preparation, assembly, or original installation of the property with respect to which such expenditure is made has been completed in a manner that is deemed to be adequate by a State- certified inspector. ``(e) Labor Costs.--For purposes of this section, expenditures for labor costs properly allocable to the onsite preparation, assembly, or original installation of the property described in subsection (c) shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year. ``(f) Inspection Costs.--For purposes of this section, expenditures for inspection costs properly allocable to the inspection of the preparation, assembly, or installation of the property described in subsection (c) shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year.''. (b) Conforming Amendment.--The table of sections for subpart A of part IV of subchapter A of chapter 1 of such Code, as amended by section 2, is amended by inserting after the item relating to section 25E the following new item: ``Sec. 25F. Hurricane, earthquake, and tornado mitigation property.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2008. SEC. 4. BUSINESS RELATED CREDIT FOR HURRICANE, EARTHQUAKE, AND TORNADO MITIGATION. (a) In General.--Subpart D of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 is amended by adding at the end the following new section: ``SEC. 45Q. HURRICANE, EARTHQUAKE, AND TORNADO MITIGATION CREDIT. ``(a) General Rule.--For purposes of section 38, the hurricane, earthquake, and tornado mitigation credit determined under this section for any taxable year is an amount equal to 25 percent of the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year. ``(b) Maximum Credit.--The amount of the credit determined under subsection (a) for any taxable year shall not exceed $5,000. ``(c) Qualified Hurricane, Earthquake, and Tornado Mitigation Expenditure.--For purposes of this section-- ``(1) In general.--The term `qualified hurricane, earthquake, and tornado mitigation property expenditure' means an expenditure for property-- ``(A) to improve the strength of a roof deck attachment, ``(B) to create a secondary water barrier to prevent water intrusion, ``(C) to improve the durability of a roof covering, ``(D) to brace gable-end walls, ``(E) to reinforce the connection between a roof and supporting wall, ``(F) to protect openings from penetration by windborne debris or wind-driven rain, or ``(G) to protect exterior doors and garages, in a qualified place of business located in a qualified State and owned by the taxpayer. ``(2) Qualified place of business.--The term `qualified place of business' means a place of business that is assessed at a value that is less than $5,000,000 by the locality in which such business is located and with respect to the taxable year for which the credit described in subsection (a) is allowed. ``(3) Qualified state.--The term `qualified State' means Alabama, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, or Virginia. ``(d) Limitation.--An expenditure shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year only if the onsite preparation, assembly, or original installation of the property with respect to which such expenditure is made has been completed in a manner that is deemed to be adequate by a State- certified inspector. ``(e) Labor Costs.--For purposes of this section, expenditures for labor costs properly allocable to the onsite preparation, assembly, or original installation of the property described in subsection (c) shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year. ``(f) Inspection Costs.--For purposes of this section, expenditures for inspection costs properly allocable to the inspection of the preparation, assembly, or installation of the property described in subsection (c) shall be taken into account in determining the qualified hurricane, earthquake, and tornado mitigation property expenditures made by the taxpayer during the taxable year.''. (b) Conforming Amendments.-- (1) Section 38(b) of such Code is amended by striking ``plus'' at the end of paragraph (32), by striking the period at the end of paragraph (33) and inserting ``, and'', and by adding at the end the following new paragraph: ``(34) the hurricane, earthquake, and tornado mitigation credit determined under section 45Q(a).''. (2) The table of sections for subpart D of part IV of subchapter A of chapter 1 of such Code is amended by adding at the end the following new item: ``Sec. 45Q. Hurricane, earthquake, and tornado mitigation credit.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2008.

Homeowners Insurance and Mitigation Assistance Act of 2008 - Amends the Internal Revenue Code to allow tax credits for: (1) 50% of the increases in homeowners insurance premiums for taxpayers whose principal residences are located in certain federally declared hurricane disaster areas or in states which border the Atlantic Ocean or the Gulf of Mexico, up to $500 annually; and (2) 25% of the qualified hurricane, earthquake, and tornado mitigation property expenditures of homeowners and businesses, up to $5,000 annually. Includes within the definition of "qualified hurricane, earthquake, and tornado mitigation expenditures" expenditures for property to improve the strength of a roof deck attachment, create a secondary water barrier, improve the durability of a roof covering, reinforce the connection between a roof and a supporting wall, and protect exterior doors and garages.

every year between the 1200 to 1400 persons per million develop urinary calculosis with a male to female ratio of 3:1 ( 1 ) . urology is probably the oldest branch of surgery , knowing that one of the first operations was safe and resolve stone jammed on the outer opening of the urethra ( 2 ) . creation of stones in the urinary organs ( urolithiasis ) is a very common disease ( 3 ) . epidemiological data suggest an increased prevalence of upper urinary tract calculi in developed countries ( 4 ) . various authors suggest that urinary calculi constitute 1 - 3 per thousand total hospitalized patients which makes 15 - 24% of patients in the urology departments ( 5 ) . this disease have several names : nephrolithiasis meaning kidney stone , nephrolithiasis and the word is derived from the greek word nephros ( kidney ) and lithos ( stone ) . word of urolithiasis urinary ( urine ) stone is derived from the french word urine and greek ouron meaning urine . it is also used as renal calculus from the latin word calculus ( plural calculi ) , which means gravel . urolithiasis also affects animals : the stones were found in dogs , cats , rabbits , minks , etc . , and the components are the same as in humans ( 1 ) . urolithiasis occurs during the most productive human age from 30 to 50 years of age , but has been described in all age groups ( 6 ) . it is believed that 12% of men and 4% of women in developed countries suffer from urinary stones . in case of a positive family history , this number doubles ( 2 ) . one of the reasons for its frequent occurrence in men is explained by the increased endogenous production of oxalate in the liver under the influence of testosterone , while in the urine of women is on average higher concentration of citrate , otherwise , increase the solubility of calcium . calculosa with women predominantly induced urinary infections and metabolic disorders , while in men predominate idiopathic lithiasis or calcium lithiasis and uric acid ( 5 ) . percentage of recurrent calculosis is 50% within 5 years and 70% over 10 years ( 8) . one of the most common pathological conditions in human medicine is the presence of a stone in the urinary tract , characterized more often as urolithiasis . in countries with developed industry the disease usually affects people in the fourth and fifth decade of life who are working , and their absence from work due to healing has significant social and economic implications on the society . localization of the stone is determined by several factors , including even the demographic characteristics . in developed countries , 97% of the stones are localized in the kidney and ureter where in 59% of cases in the ureter . urethral stone is in 75% of cases located in the iliac and pelvic part of the ureter ( 1 , 3 ) . if the calculi in their characteristics are not spontaneously eliminated , taken are further steps and therapeutic protocols to solve this problem . asperitan stone and stone larger than 7 mm in diameter , which practically can not be spontaneously eliminated , threatening development of kidney urostasis and infection ( 2 ) . indications for an active therapeutic approach to ureter stones is stone diameter over 7 mm with low ( below 20% ) probability of spontaneous elimination or absence of spontaneous stone elimination of any size for a period longer than 30 days from the first renal colic , urinary infection develop , sepsis , calculous anuria , as well as the request of patients . treatment of urolithiasis includes conservative , surgical treatment , and treatment with extracorporeal shock wave lithotripsy ( eswl ) depending on the evaluation . recently , endoscopic procedures , such as eretheroscopy ( urs ) and percutaneous lithotripsy ( pcnl ) , together with the aforementioned eswl , have been almost entirely replaced open surgery , so in just 30 years , radically changed the approach and functional outcome of this disease ( 1 , 2 ) . eswl treatment is the first - line treatment of urinary tract stones , but there are still no clearly defined limits and recommendations for its use in the treatment of urinary calculi , depending on its location , size and morphological structure . this raises the question of efficiency of eswl depending on the characteristics of urinary calculi . determine characteristics of the patients with calculi in the urinary system , possibilities of disintegration of stones and its spontaneous elimination dependent on morphological structure of stones , their size and location in the urinary tract . it was conducted at the urology clinic clinical center of sarajevo university in the period from 2007 to 2013 . all patients prior to initiation of therapy eswl treatments were subjected to the following diagnostic procedures : anamnesis , clinical examination of patients , laboratory tests , ultrasound examination of the urinary tract and urinary tract x - ray , from which was derived chemical qualitative analysis of morphological stone composition . diagnostics are used in the detection of complications such as obstruction with dilatation of the renal colorectal system , reduction of the renal parenchyma and in monitoring of renal obstruction during treatment . this type of diagnosis is not suitable for stones in the ureter and can make the difference between calcified and radiolucent concrement . eswl treatment is performed on the machine siemens model lithostar multiline , which has a combined ultrasonographic and fluoroscopic display , large energy density in order to obtain optimum focus ( without damaging surrounding tissue ) and minimal pain that on rare occasions requires for mild sedation - sedation . for nominal and ordinal variables chi - square test was used . in cases when the frequency was lower than expected statistical analysis was performed using spss computer software for statistical analysis ( spss statistical package for the social sciences ) version 13.0 . from a total of 404 patients included in the study there were 234 ( 57.92% ) male and 170 ( 42.08% ) female patients . the most common age group in the sample was at age from 35 to 45 years and consisted of 110 respondents ( 27.09% ) . the minimum number of respondents had the age over 65 years 19 respondents ( 4.67% ) . the most common type of stone both in female and male patients was calcium type . from a total of 262 calcium stones , 105 of them ( 40.07% ) was present in female patients and 157 ( 59.92% ) in male . share of infectious type of stone in female patients was 63 ( 49.60% ) and 64 among males ( 50.39% ) . other stones were less abundant in both the gender groups and their total number was only 17 . in women their frequency was 2 ( 13.33% ) and 13 among males ( 86.67% ) . there was a significant difference in the frequency of different types of stones by gender ( 2 = 11.47 , p = 0.009 ) . due to the very low prevalence of other types of stones and inability to perform the chi - square test to a group of other stones are grouped stones which , by virtue were cystine , xanthine stones and uric acid stones . the incidence of cystine calculi was 4 ( 0.9% ) , frequency of xanthine stones 3 ( 0.7% ) and uric acid 8 ( 1.9% ) . in the group of female respondents 74 ( 40.88% ) had calculus size up to 10 mm , while in the group of male patients stone size up to 10 mm had 107 ( 59.12% ) . in the group of female respondents 96 of them ( 43.05% ) had a size of stone exceeding 10 mm , while in the group of male patients stone size over 10 mm had 127 ( 56.95% ) . there was no statistically significant difference in the incidence of stones with sizes up to 10 and over 10 mm by gender ( 2 = 0.192 , p = 0.661 ) number of stones localized in the upper pole of the kidney in women was 43 ( 48.86% ) , and among men was slightly lower and amounted to 45 ( 51.13% ) . number localized in the lower pole of the kidney in women was 22 ( 61.11% ) , and among men was slightly lower and amounted to 14 ( 38.88% ) . number of stones localized medially among women was 38 ( 45.78% ) , and among men was slightly lower and amounted to 45 ( 54.21% ) . number of localized in the renal pyelon in females was 27 ( 40.39% ) , and among men was slightly lower and amounted to 40 ( 59.70% ) . there was no statistically significant difference in the frequency of localization of stones by gender . the incidence of urolithiasis at the site of physiological narrowing of the ureter in female subjects was 22 ( 27.5% ) and 58 in males ( 72.5% ) . the incidence of urolithiasis at the site of the physiological enlargement of the ureter in female subjects was 8 ( 50% ) , and the same among men 8 ( 50% ) . there was no statistically significant difference in the frequency of localization of calculi to physiological narrowing and widening of the ureter in relation to gender differences ( p = 0.086 ) . the second most common size of the calculi in the sample was 9 mm , which had 14.6% of respondents , followed by the size of 20 mm , which had 14.38% of the respondents . the least frequent size calculi were 17 mm , which was only 0.25% of the respondents . size of the calculi in women was 12 ( 8 - 15 mm ) , while in men it was 12 ( 8 - 15 mm ) . there was no statistically significant difference in the size of calculi between males and females ( p = 0.557 ) . there was a significant mild positive correlation between age and size of the stone in the total sample ( rho = 0.240 , p < 0.01 ) , i.e. increase with age slightly increases the size calculi . in the group of patients who had a negative family history of calculus size to 10 mm were present in 108 ( 59.67% ) , while in the group of subjects who had a family history size of stones up to 10 mm had 73 ( 40.33% ) . in the group of patients who had a negative family history of calculus size over 10 mm was registered in 160 ( 71.75% ) , while in the group of subjects who had a positive family history of calculus size over 10 mm was registered in 63 ( 28.25% ) . there was a statistically significant correlation between the size of stones and positive / negative family history ( 2 = 6.529 , p = 0.011 ) , respectively , in patients with a positive family history more often were present small stones ( to 10 mm ) . size of the calculi in patients who had a positive family history was 12 ( 9 - 15 mm ) , while the size of stones in patients who had a positive family history was 10 ( 8 - 15 cm ) . there was no statistically significant difference in the size of the stones between the groups of patients ( p = 0.013 ) . size of calculus in patients without recurrent urolithiasis was 11 ( 9 - 15 mm ) , while the size of the calculus in patients who have had recurrent urolithiasis was 12 ( 8 - 15 mm ) . there was no statistically significant difference in the size of calculi between groups of patients ( p = ns ) . frequency of localization in the upper pole of kidney which have the size of 10 mm was 30 ( 34.09% ) , while the frequency of localization in the top half of kidney s which had more than 10 mm in size was 58 ( 65.91% ) ( table 1 ) . fisher exact test ; p=0.003 frequency of localization in the lower pole of the calculi that had the size of 10 mm was in 3 cases ( 8.33% ) , while the frequency of localization in the lower pole of the calculi that had the size over 10 mm was present in 33 cases ( 91.67% ) . there was a significant dependence between the size of the stone and the same localization in renal pole ( fisher 's exact test , p = 0.003 ) . looking at the frequency of stones it is a lot bigger on the top half , but looking at their size , larger stones ( over 10 mm ) were significantly more often present in the lower half . size of calculi localized medially was 14 ( 10 - 15 mm ) , while the localization pyelon was 15 ( 12 - 18 mm ) . there was a significant difference in size between the mentioned calculus localization ( p = 0.022 ) . stones that occur in the renal pyelon are higher than the stones that are found in our study , in medial position . frequency medial localization of calculi which size was less than 10 mm was 33 ( 39.75% ) , and frequency of 50 ( 60.25% ) for stones ranging in size over 10 mm . pyelon localization of calculi which size was less than 10 mm was 5 ( 7.46% ) , and frequency of 62 ( 92.53% ) for stones ranging in size over 10 mm . there was a significant correlation between the size of the stone and localization of stones ( medial / pyelon ) ( 2 = 20.443 , p < 0.001 ) . frequency of calculi localization at sites of physiological stricture site that had the size of 10 mm was 68 ( 85% ) , while the frequency of localization at sites of calculi physiological stricture site which had the size over 10 mm was 12 ( 15% ) . frequency of localization at sites of calculi enlargement physiological ureter which had the size of 10 mm was 15 ( 93.75% ) , while the frequency of localization at sites of calculi enlargement physiological ureter which had the size over 10 mm , was 1 ( 6.25% ) . there was no statistically significant dependence between the size of tartar and calculus localization to physiological constriction and expansion of the ureter ( p = 0.688 ) ( table 2 ) . e1- physiological narrowing of the ureter , e2 physiological enlargement of the ureter in the group of patients under 35 years the incidence of calcium stones was 88 ( 33.58% ) , while in the age group of 35 - 55 years the incidence of calcium type of calculi was 135 ( 51.52% ) . the frequency of this type of calculi in subjects older than 55 years was 39 ( 14.88% ) . in the group of patients under 35 years the incidence of infectious stones was 26 ( 20.47% ) , and at the age of 35 to 55 years the incidence of infectious types of calculi was 63 ( 49.60% ) . the frequency of this type of calculi in subjects older than 55 years was 38 ( 29.92% ) . in the group of patients under 35 years the incidence of other types of stones was 4 ( 26.66% ) , while in the age group of 35 - 55 years the incidence of other types of calculi was 7 ( 46.66% ) . the incidence of other types of calculi in subjects older than 55 years was 4 ( 26.66% ) . statistically significant dependence between age and type of calculi ( 2 = 15.170 , p = 0.004 ) ( table 3 ) . renal lithiasis is a disease in which the stones were formed in the collecting tubules , cups and pyelon . the incidence was similar in both kidneys , and about 40% of patients had bilateral stones . there is a wide range of risk factors that may be associated with the disease , including local and general factors . of local risk factors that favor the emergence of this disease are : trail of urine , disorders of innervation , anomalies of drainage pathways , anatomical abnormalities ( sponge kidney , horseshoe kidney ) , and recurrent infection . general risk factors are categorized as : metabolic ( calciuria , cystinuria ) , hormonal ( primary hyperparathyroidism , hyperthereodosis and hypovitaminosis ) and other factors such as climatic conditions of life , feeding , ph of urine excretion of concentrated urine , prolonged immobilization , etc . . formation of kidney stones attempted to explain many theories but none fully explains the mechanism of occurrence . urine is in the usual conditions supersaturated solution in which the particles are held in solution influence crystallization inhibitor and colloids . if these factors are disrupted leads to precipitation and aggregation of crystals . the organic matrix , which consists of cellular detritus , blood and bacteria may be the main factor that leads to nucleation and crystal growth . there is a theory which states that the formation of stones occurs when the crystals , which are constantly being created in the urine oversaturated with salts , are not washed away in the urine . this may occur due to damage to the epithelial duct to which it adheres crystal ( 11 ) . changes in the socio - economic conditions have influenced the changes in the frequency and type of urolithiasis in terms of localization and physico - chemical properties of stones . major variations on the occurrence of urolithiasis in the world are presented to the public in terms of geographical areas . annual incidence in england is 22 cases per 100,000 inhabitants , in kuwait 23.9 per 100,000 population . however , in some countries there are significant differences in the incidence , such as sweden , where the incidence of 140 per 100,000 inhabitants , italy 168 per 100,000 inhabitants and united states with high prevalence of 277 per 100,000 population . in europe , urinary stones are found mainly in the upper urinary tract , while the proportion of stones in the bladder does not exceed 10.0% . it is shown that the urinary bladder calculi more common in the elderly ( 12 ) . the disease is more common in men and usually occurs after the third decade of life . it is shown that caucasians are more likely to develop kidney stones than african americans , and men more often than women patients . a possible explanation why men are more frequent in patients than in females lies in the fact that men in performing physical activities much sweat and lose a lot of fluid , which is also the main reason for the formation of a kidney stone or a stone in the bladder ( 1 ) . some new studies are mostly directed of change in the relationship of occurrence calculi in men and women . in the united states and the data showed that the overall incidence of urolithiasis 10.6% for men and 7.1% for women . this is explained by balancing risks for both men and women today , compared to the past when they were significantly different ( 13 ) . results of this study showed that the total number of subjects included higher percentage occupied by male respondents and 57.92% , while the remaining 42.08% are occupied by the respondents are female . the results are consistent with published data showing a higher incidence of this disease in male patients compared to female respondents . greater tendency of men to concentrate urine compared to the opposite sex , may be the reason for higher incidence of this disease in men . it is shown that the higher the osmolality in men also work super saturation which is responsible for the crystallization of poorly soluble compounds . even if the concentration of poorly soluble compounds reaches the threshold of saturation of the total 24-h urine , then it can exceed during transient episodes , the way to increase the intake of foods rich in protein , at night , or during intense exercise , especially in the summer months , or season in which men showed a significant decrease in urine volume . although urolithiasis 2 - 3 times more common in men , there are no studies that clearly define the reasons for variations incidence of this disease ( 1,3 ) . daudon and colleagues ( 14 ) show that men older than 80 years constitute 40.0% of the analyzed patients with urinary bladder calculi . prostatic hyperplasia is more common in the elderly and causes an obstruction in the urinary tract . this may be a possible explanation for the high incidence of stones in the bladder in the elderly . women are also at risk calculus appears in the lower parts of the urinary tract . this suggests the existence of other risk factors , such as changes in bladder function associated with relaxation of smooth muscle tone in the elderly , with an efficiency reduction bladder emptying favoring stagnation of urine and the occurrence of tartar . when it comes to the size calculi , the results of our study showed a statistically significant positive correlation between age and size of the stone in the total sample ( rho = 0.240 , p < 0.01 ) . classifying respondents into three age groups , our results showed that the highest incidence of stones measuring greater than 10 mm was represented at the age between 35 and 55 years . chi - square test showed a statistically significant correlation between age and size of the stone ( 2 = 40.287 , p < 0.00005 ) . the study by alaya and associates ( 12 ) , who analyzed the sample of 1301 urinary tract stones , it has been proven that the highest percentage share of 58.6% occupied stones of calcium type , that type of calcium oxalate , but they also recorded an increase in the incidence and types of stones uric acid . the authors believe that in the last 50 years there has been a change in eating habits associated with an increase in foods rich in purines ( animal proteins projections and seafood ) , which correlates the increase in uric acid in the urine , and increasing incidence of this type of calculi . the results of our study showed that the group of patients under 35 years the incidence of calcium stones was 33.58% , the incidence of infectious stones 20.47% , while the incidence of other types of stones was 26.66% . at the age of 35 to 55 years the incidence of a calcium type of calculi was 51.52% , the frequency of the infectious type of calculi was 49.60% , and the prevalence of other types of stones was 46.66% . the frequency of this type of calcium calculi in subjects older than 55 years was 14.88% , infectious stones were 29.92% , while the incidence of other types of calculi in subjects older than 55 years was 26.66% . there was a statistically significant correlation between age and type of calculi ( 2 = 15.170 , p = 0.004 ) , i.e. among younger patients are the most common types of calcium stones , while the incidence of infectious types of stones rarer . increasing age leads to equalization of the frequency of calcium and infectious stones . differences in the incidence of age and stones were analyzed through a large number of epidemiological studies . baker et al ( 15 ) reported that in australia peak incidence of urolithiasis calcium oxalate sampled observed in individuals between 50 and 60 years of age . in europe , research shows that the stones which are chemically calcium oxalate more common in people between 40 and 50 years of age . in asia , the highest prevalence of calcium oxalate stone formation occurs at an earlier age range 30 to 50 years ( 1 ) . certain hereditary disorders that run in the family increases the risk of recurrent kidney stones . a rare hereditary disease , renal tubular acidosis , increases the acidity of urine , which is favorable for the occurrence of kidney stones . cystinuria is a hereditary disorder of the metabolism of amino acids , which results in high levels of cystine in the urine and blood , leading to frequent formation of cystine kidney stones . second , a hereditary disorder of metabolism , hyperoxaluria , is resulting in high levels of oxalate salt in the body , which is combined with calcium in the form of kidney stones . hypercalciuria causes high accumulation of calcium in the body , which increases the incidence of kidney stones . hiperuricosuria increased level of uric acid in the urine , which leads to the formation of uric acid stones ( 1,3 ) . diet , in terms of animal protein ( 52 g / day ) , sodium ( 50 mg / day ) and the oxalate ( 200 mg / day ) with a normal intake of calcium ( 1,200 mg / day ) , reduced recurrent stones for almost 50% and more , within five years , compared to a diet low in calcium ( 400 mg / day ) and oxalate ( 16 ) . our results show that the proportion of respondents who did not have positive personal and family history of urolithiasis was 44.94% , and patients who had a positive family history of urolithiasis , but he had a personal history was 50.05% . the share of respondents , who had a family history , and negative personal history of urolithiasis , was 42 ( 30.88% ) , while the number of respondents who had a positive to families and personal history was 136 ( 33.74% ) . there was a significant frequency dependence of family and personal history ( 2 = 7.41 , p = 0.006 ) , i.e. higher incidence of recurrence in patients who have a positive family history of urolithiasis . similar results were presented by the study koyuncu and associates ( 17,1 ) , which showed a significant correlation recurring calculi and positive family history . the authors also found that the time interval between the onset of recurrence was significantly shorter in patients who had a positive family history of urolithiasis . by analyzing the patients according to sex , the authors noted that the incidence of recurrence was more frequent in males than females respondents . the authors believe that the information positivity family history is very important and can provide valuable information about the possibility of future attacks as well as the severity of the disease . epidemiological and randomized studies have shown greater security eswl treatment methods in breaking stones when it starts with applying lower energy sequences of the same , with a gradual increase energy sequences , resulting in a vasoconstriction which prevents renal damage and the difference in the fragmentation is not significant despite the fact that whether amplification is carried out or not ( 1 ) . previous clinical and epidemiological studies have shown that as an indication of eswl treatment of urolythiasis depends on several factors , including the size , localization , consistency and other histological characteristics of calculi ( 1,2 ) . pregnancy and specific internship and urological diseases , with an emphasis on acute urinary infection , contraindications to perform of eswl ( 4 ) . from a total of 404 patients included in the study there was 57.92% male and 42.8% female respondents , or male : female ration of 1.2 : 1 , while the most common age group in a sample of patients with urolithiasis was between 35 and 45 years(27% ) . most frequent type of calculi both in female and male subjects was of calcium type . in younger patients the most common are calcium stones , with increase in respondents age calcium and infectious stones frequencies there was a significant correlation between the size of the stone and its localization in renal pole . the incidence of stones was significantly greater in the top half , but the size of large stones ( over 10 mm ) were significantly more present in the lower kidney pole . there was no statistically significant relationship between the size of stones and personal history , but statistically significant correlation is determined between the size of the stone and family history of urolithiasis . also there was significant correlation between the size of the stone and its localization ( medial / pyelon ) . stones up to 10 mm are more frequently localized medially , and those larger than 10 mm are somewhat more common in the pyelon .

introduction : elimination of stone is determined by size and its localization . stone from the ureter in 80% of cases can be eliminated spontaneously . if the stone by its characteristics is not spontaneously eliminated , taken are further steps and therapeutic protocols to solve this problem.material and methods : the study was prospective , open and comparative . it was conducted at the urology clinic clinical center of sarajevo university in the period from 2007 to 2013 . the study included 404 patients with urinary tract lithiasis treated by eswl . eswl treatment is performed on the machine siemens model lithostar multiline , which has a combined ultrasonographic and fluoroscopic display , large energy density in order to obtain optimum focus ( without damaging surrounding tissue ) and minimal pain that on rare occasions requires for mild sedation-sedation.results:from a total of 404 patients included in the study there were 234 ( 57.92% ) male and 170 ( 42.08% ) female patients . the most common type of stone both in female and male patients was calcium type . from a total of 262 calcium stones , 105 of them ( 40.07% ) was present in female patients and 157 ( 59.92% ) in male . share of infectious type of stone in female patients was 63 ( 49.60% ) and 64 among males ( 50.39% ) . other stones were less abundant in both the gender groups and their total number was only 17 . in women their frequency was 2 ( 13.33% ) and 13 among males ( 86.67% ) . there was a significant difference in the frequency of different types of stones by gender ( 2 = 11.47 , p = 0.009).conclusion : there was no statistically significant correlation between the number of treatments and localization of stones in the ureter , as well as a statistically significant correlation between the size of the stone and the localization of calculus in the ureter .

Mount Ontake, a volcano straddling Nagano and Gifu prefectures, erupted on Saturday, spewing ash and small rocks into the air, leaving at least 16 people unconscious and 30 others seriously injured, and stranding more than 40 on the mountain, officials and media said. Following the eruption at 11:53 a.m., a thick, rolling gray cloud of ash rose high into the sky above the mountain close to where hikers were taking pictures, TV footage showed. Hikers and residents were warned of falling rock and ash within a radius of 4 km. A Nagano prefectural official said at least 16 other people were unconscious, based on information gathered from mountain lodges where people were seeking shelter. There were also indications that more than 30 hikers were seriously wounded. At one point, more than 250 hikers had been stranded on the mountain, which is 3,067 meters high. But some 200 managed to descend by Saturday evening, police said. The remainder were forced to spend the night on the mountain until rescue work resumed Sunday morning. Nagano police sent an 80-strong team to assist climbers who were making their way down the mountain, while Kiso Prefectural Hospital, near Ontake, said it had dispatched a medical emergency team. “We expect a lot of injured people so we are now getting ready for their arrival,” said an official at the hospital. The Meteorological Agency said the volcano, about 200 km west of Tokyo, erupted just before midday and sent ash pouring down the mountain’s south slope for more than 3 km. The agency is forecasting further eruptions that may affect people living around the base of the mountain. No signs of any lava were seen in the TV report, but the footage showed dozens of hikers covered with ash hurriedly descending the mountain. Climbers reaching the bottom points of one trail grasped each other with joy and relief to have made it down. “I barely escaped,” a local resident told NHK. “Immediately after I watched the eruption, I ran away from it but I was soon covered with ash, which piled up to some 20 cm.” Prime Minister Shinzo Abe, who returned from the United States on Saturday, said he had issued instructions to mobilize the military to help in the rescue effort. “We are still trying to figure out details. I instructed that everything possible be done to rescue the people affected and secure the safety of the trekkers,” Abe told reporters. The eruption also forced aircraft to divert their routes, although officials at Tokyo’s Haneda airport and Japan Airlines Co. said there were no disruptions to flights in and out of the capital. More than five hours after the initial eruption, the thick ash cloud showed no signs of abating, NHK TV showed. “It was like thunder,” a woman interviewed by NHK said. “I heard ‘boom, boom,’ then everything went dark.” Mount Ontake’s last major eruption was in 1979, when it emitted over 200,000 tons of ash. It experienced a minor eruption in 1991 and triggered multiple volcanic earthquakes in 2007. With a relatively easy climb, lodges along the way and a ropeway running part of the way to the summit, the mountain is popular with outdoor enthusiasts for its autumn scenery, drawing large crowds in late September and October, according to the local tourism association. “It’s all white outside, looks like it has snowed. There is very bad visibility and we can’t see the top of the mountain,” Mari Tezuka, who works at a mountain hut for trekkers, said. “All we can do now is shut up the hut and then we are planning on coming down. … This is a busy season because of the changing autumn leaves. It’s one of our busiest seasons.” ||||| TOKYO (AP) — A volcano in central Japan erupted in spectacular fashion on Saturday, catching mountain climbers by surprise and injuring at least 11 people, including seven who lost consciousness. Dense fumes are spewed out from several spots on the slope of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high... (Associated Press) Mountain lodge buildings totally covered by ash stand on the edge of the crater as white plumes are spewed out from Mt. Ontake in central Japan Saturday, Sept. 27, 2014. With a sound likened to thunder,... (Associated Press) Buildings of a mountain lodge near the summit crater are totally covered by ash spewed out by Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending... (Associated Press) Dense fumes are spewed out from several spots on the slope of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high... (Associated Press) Dense fumes are spewed out from Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high into the sky and prompting a... (Associated Press) Dense fumes are spewed out from Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high into the sky and prompting a... (Associated Press) Dense plumes are spewed out from the crater of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. With a sound likened to thunder, the 3,067-meter (10,062-foot) mountain spewed... (Associated Press) With a sound likened to thunder, Mount Ontake erupted shortly before noon on a clear autumn day, spewing large white plumes of ash high into the sky and sending people on the mountainside fleeing. The eruption continued into the night, blanketing the surrounding area in ash. More than 250 people were stuck on the slopes for hours, many taking refuge in mountain lodges that dot the way up. By evening, most had made or were making their way down, though some decided to spend the night. Some with injuries didn't want to risk coming down the ash-covered paths. As of late afternoon, eleven people had been reported injured, eight seriously, including the seven who lost consciousness, said Nagano prefecture crisis management official Minoru Kashiwabara. One witness told Japanese public broadcaster NHK that the eruption started with large booms that sounded like thunder. In a YouTube video, shocked climbers can be seen moving quickly away from the peak as an expanding plume of ash emerges above and then engulfs them. Many of those who made it down emerged with clothes and backpacks covered in ash. They reported being engulfed in total darkness for several minutes. Mikio Oguro, an NHK journalist who was on the slope on an unrelated assignment, told the station that he saw massive smoke coming out of the crater, blocking sunlight and reducing visibility to zero. "Massive ash suddenly fell and the entire area was totally covered with ash," he said by phone. He and his crew had to use headlamps to find a lodge. "My colleagues later told me that they thought they might die," Oguro said. Two Jetstar flights headed to Tokyo's Narita International Airport diverted to Kansai International Airport in western Japan as a precaution. Japan's meteorological agency raised the alert level for Mount Ontake to 3 on a scale of 1 to 5. It warned people to stay away from the mountain, saying ash and other debris could fall up to 4 kilometers (2.5 miles) away. The 3,067-meter (10,062-foot) Mount Ontake sits on the border of Nagano and Gifu prefectures, on the main Japanese island of Honshu. The volcano's last major eruption was in 1979. ___ Online: http://www.youtube.com/watch?v=7Ea3uED1Zgc#t=54 ||||| A helicopter (R top) flies near rising smoke and mountain lodges (R bottom) covered with volcanic ash near a crater of Mount Ontake, which straddles Nagano and Gifu prefectures September 27, 2014, in this photo taken and released by Kyodo. TOKYO A Japanese volcano popular with hikers erupted on Saturday, killing one woman and seriously injuring more than 30 people, officials and media said. The mountain draws walkers who come to admire the autumn colors on the trees. "It was like thunder," a woman told public broadcaster NHK of the first eruption at the volcano in seven years. "I heard boom, boom, then everything went dark." The Japan Meteorological Agency said the volcano, Mount Ontake, which straddles Nagano and Gifu prefectures 200 km (125 miles) west of Tokyo, erupted just before midday and sent ash pouring down the mountain's south slope for more than three km (two miles). Tokyo's Haneda airport said incoming domestic flights were experiencing delays of about 40 to 50 minutes because they were forced to change routes. International flights to and from Haneda were not affected by the eruption, the airport said. NHK, citing the local fire brigade, reported that one woman had been confirmed dead. More than 30 people were seriously injured and 10 of them were unconscious, it said. According to police, more than 250 hikers at one stage had been stranded on the mountain, which is 3,067 meters (10,062 feet) high and last erupted in 2007. No nuclear power plants are located nearby. NHK said about 230 hikers had made their way down the mountain, while 41 people remained stranded and were expected to try descending the next day. Prime Minister Shinzo Abe, who returned from the United States on Saturday, said he had ordered the military to help in rescue efforts. "I instructed to do all we can to rescue the people affected and secure the safety of the trekkers," Abe told reporters. Nagano police sent a team of 80 to the mountain to assist the climbers, while Kiso Prefectural Hospital, near the mountain, said it had dispatched a medical emergency team. "We expect a lot of injured people so we are now getting ready for their arrival," said an official at the hospital. As of 8:30 p.m. local time, the eruption was continuing, NHK said. "It's all white outside, looks like it has snowed. There is very bad visibility and we can’t see the top of the mountain," Mari Tezuka, who works at a mountain hut for trekkers, told Reuters. "All we can do now is shut up the hut and then we are planning on coming down... This is a busy season because of the changing autumn leaves. It's one of our busiest seasons." (Reporting by Antoni Slodkowski, Mari Saito and Kiyoshi Takenaka; Writing by Kiyoshi Takenaka; Additional reporting by Chris Gallagher; Editing by Nick Macfie and Stephen Powell) ||||| TOKYO (AP) — A volcano in central Japan erupted in spectacular fashion on Saturday, catching mountain climbers by surprise and stranding at least 40 injured people in areas that rescue workers have been unable to reach. Another seven people were missing. In this photo taken by an anonymous climber and was offered to Kyodo News, dense plumes rising from the summit crater of Mount Ontake cover the slope carpeted by colored autumn leaves after the volcanic... (Associated Press) Dense white plumes rise high in the air as Mt. Ontake erupts in central Japan, Saturday, Sept. 27, 2014. With a sound likened to thunder, the 3,067-meter (10,062-foot) mountain spewed large white plumes... (Associated Press) In this photo taken by an anonymous climber and was offered to Kyodo News, climbers descend Mt. Ontake to flee as the volcanic moutain erupts in central Japan, Saturday, Sept. 27, 2014. With a sound likened... (Associated Press) Climbers descended to a parking lot located halfway up Mt. Ontake rest after fleeing from the volcano eruption, in Kiso in Nagano Prefecture, central Japan, Saturday, Sept. 27, 2014. With a sound likened... (Associated Press) Mountain lodge buildings totally covered by ash stand on the edge of the crater as white plumes are spewed out from Mt. Ontake in central Japan Saturday, Sept. 27, 2014. With a sound likened to thunder,... (Associated Press) Dense fumes are spewed out from several spots on the slope of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high... (Associated Press) Buildings of a mountain lodge near the summit crater are totally covered by ash spewed out by Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending... (Associated Press) Dense fumes are spewed out from several spots on the slope of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high... (Associated Press) In this photo taken by an anonymous climber and was offered to Kyodo News, dense plumes rise from the summit crater of Mt. Ontake shortly after the volcanic mountain erupts in central Japan, Saturday,... (Associated Press) Dense fumes are spewed out from Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high into the sky and prompting a... (Associated Press) Dense fumes are spewed out from Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. Mt. Ontake erupted Saturday, sending a large plume of ash high into the sky and prompting a... (Associated Press) Dense plumes are spewed out from the crater of Mt. Ontake as the volcano erupts in central Japan Saturday, Sept. 27, 2014. With a sound likened to thunder, the 3,067-meter (10,062-foot) mountain spewed... (Associated Press) In this photo taken by an anonymous climber and was offered to Kyodo News, climbers descend Mt. Ontake to flee as the volcanic mountain erupts in central Japan, Saturday, Sept. 27, 2014. With a sound... (Associated Press) In this photo taken by an anonymous climber and was offered to Kyodo News, climbers descend Mt. Ontake to flee as the volcanic moutain erupts in central Japan, Saturday, Sept. 27, 2014. With a sound likened... (Associated Press) The injured, unable to descend 3,067-meter (10,062-foot) Mount Ontake on their own, are staying in mountain lodges, said Sohei Hanamura, a crisis management official in Nagano prefecture. Thirty-two people had serious injuries, including at least seven who lost consciousness. Police, fire and military rescue workers were planning to try to reach the area on foot after daybreak Sunday, after deciding that the ash in the air made it too dangerous to use helicopters. Hanamura said seven people were reported missing on the mountain. Lodge managers are familiar with first aid procedures and were communicating with rescue officials in town, he said. With a sound likened to thunder, the volcano erupted shortly before noon on a clear autumn day, spewing large white plumes of gas and ash high into the sky and blanketing the surrounding area in ash. Smaller eruptions continued into the night. About 250 people were initially trapped on the slopes, but most had made their way down by Saturday night, Japanese public broadcaster NHK reported. Some were in shelters set up in four nearby towns. One witness told NHK that the eruption started with large booms that sounded like thunder. In a video posted on YouTube, shocked climbers can be seen moving quickly away from the peak as an expanding plume of ash emerges above and then engulfs them. Many of those who made it down emerged with clothes and backpacks covered in ash. They reported being engulfed in total darkness for several minutes. Mikio Oguro, an NHK journalist who was on the slope on an unrelated assignment, told the station that he saw massive smoke coming out of the crater, blocking sunlight and reducing visibility to zero. "Massive ash suddenly fell and the entire area was totally covered with ash," he said by phone. He and his crew had to use headlamps to find a lodge. "My colleagues later told me that they thought they might die," Oguro said. Two Jetstar flights headed to Tokyo's Narita International Airport diverted to Kansai International Airport in western Japan as a precaution. Japan's meteorological agency raised the alert level for Mount Ontake to 3 on a scale of 1 to 5. It warned people to stay away from the mountain, saying ash and other debris could fall up to 4 kilometers (2.5 miles) away. Mount Ontake, about 210 kilometers (130 miles) west of Tokyo, sits on the border of Nagano and Gifu prefectures, on the main Japanese island of Honshu. The volcano's last major eruption was in 1979. ___ Associated Press writer Mari Yamaguchi contributed to this report. ___ Online: http://www.youtube.com/watch?v=7Ea3uED1Zgc#t=54

– A volcano in Japan rumbled to life today unexpectedly, killing a female hiker, the Japan Times reports. At least 40 people were hurt in the eruption of Mount Ontake in central Japan, the AP reports, and the Times notes that 16 were knocked unconscious, per an official. Seven were said to be missing. The mountain spewed ash and initially trapped about 250 hikers on its slopes, reports Reuters. The eruption occurred at midday local time, and by evening most of the trapped hikers had made it down to safety, reports the AP. Many injured, however, are staying in lodges on the mountain. Given the scope of the smoke and ash plumes, it could take a while to account for everyone. "It was like thunder," a woman tells broadcaster NHK of the first eruption. "I heard boom, boom, then everything went dark." The 10,062-foot Mount Ontake is about 125 miles west of Tokyo, on the border between Nagano and Gifu prefectures, and Reuters says it last erupted in 2007. "It's all white outside, looks like it has snowed," an employee of a mountain hut for hikers told the news agency about five hours after the first eruption. "There is very bad visibility and we can’t see the top of the mountain." (Click to read about how a commonly accepted explanation about volcanoes might be wrong.)

in the rotating wave approximation , the three - level system is described by the hamiltonian @xmath124 where @xmath19 is the atomic projection / transition operator , @xmath20 . the external driving microwave fields at frequencies @xmath22 and @xmath23 couple atomic states according to the interaction hamiltonian @xmath125,\ ] ] where @xmath25 is the dipole interaction energy for the transition @xmath26 under the influence of the field in the transmission line with the actual current given by @xmath27 = i_{ij}\cos{\omega_{ij}^d t}$ ] . here we assume that our pointlike atom is situated at @xmath28 and the waves from microwave sources @xmath29 ( with the wavevector @xmath30 ) propagate in the transmission line . the dipole matrix element can be presented in the form @xmath31 with the dimensionality of a magnetic flux , where the dimensionless matrix element @xmath126 satisfies the condition of @xmath32 , @xmath0 is the line - atom mutual inductance , and @xmath127 is the amplitude of the persistent current in the loop . the atomic dynamics is described by the standard master equation for the density matrix @xmath34 , @xmath128+l[\rho]\ ] ] with the lindblad term @xmath129 here @xmath36 is the damping rate of the off - diagonal terms ( dephasing ) and @xmath37 is the relaxation rate between the levels @xmath1 and @xmath38 ( @xmath39 ) . in the ladder - type three - level atom , the @xmath130 transitions can be neglected since @xmath40 . our experiment is performed at the temperature @xmath12 , low compared to the atomic energy splitting ( @xmath13 ) , which guarantees the absence of thermal excitations ( @xmath41 = 0 , @xmath42 = 0 and @xmath43 = 0 ) . the atom interacting only with continuum modes of 1d open space generates a scattered wave @xcite @xmath131 where @xmath45 = \rho_{ji}$ ] can be straightforwardly found in the stationary conditions ( @xmath46 ) , when the master equation reduces to a set of linear algebraic equations . the transmission coefficient found as a ratio of the resulting current @xmath47 ( at @xmath48 ) to the incident one @xmath49 takes the form @xmath132 from eq . ( [ st ] ) , the amplification condition is @xmath133 in the case of weak drive ( probe ) at around @xmath6 , when it does not change the population of levels , solutions for the density matrix elements are @xmath134 @xmath135 @xmath136 @xmath137 where @xmath138 , @xmath57 , @xmath58 , @xmath139 , @xmath140 , @xmath141 . equation ( [ rho21 ] ) simplifies for the most interesting case of nearly resonant drives and fast @xmath52 relaxation ( @xmath53 ) , where the state @xmath14 remains nearly unpopulated ( @xmath54 ) . neglecting the terms @xmath55 , we arrive at @xmath142 from which , according to eq . ( [ t ] ) , @xmath143 this equation gives the standard population inversion condition for the amplification @xmath144 with the required pumping amplitude @xmath145 for weak pure dephasing between the ground and the second excited states , the total dephasing is simplified to @xmath61 and the amplification condition takes the form @xmath146 one interesting consequence of eq . ( [ tt ] ) is that @xmath91 becomes insensitive to low frequency fluctuations between @xmath64 and @xmath77 at some optimal driving amplitude @xmath16 . magic " point , where the pure dephasing is suppressed ( @xmath97 ) , takes place at @xmath98 because the denominator of @xmath91 in eq . ( [ t ] ) contains a linear term @xmath147 , while its numerator does not depend on @xmath92 . the interesting question : what is the maximal possible gain of the single - atom amplifier ? we consider the ideal case of absence of pure dephasing [ @xmath97 , @xmath148 , @xmath149 ( because @xmath150 ) ] @xmath63 from eq . ( [ tt ] ) in the double resonance @xmath95 and @xmath151 . when the pumping amplitude @xmath16 is of order of the threshold defined by eq . ( [ omegaamp ] ) , the atomic populations can be expressed as @xmath102 and @xmath103 , where @xmath104 is the square of the normalized pumping . the transmission coefficient @xmath152 reaches its maximum at @xmath107 , that is @xmath153 which corresponds to the gain @xmath154 the spontaneous emission spectrum of the on - chip single atom is affected by a strong pumping @xmath16 . we find the emission power spectral density of the waves , propagated in one direction ( forward or backward ) , for @xmath155 transition @xcite @xmath156 the fact that only half power is detected is accounted as a 1/2 factor in the equation . in the condition of resonant pumping at @xmath8 , we find a form of eq . ( [ master ] ) @xmath157 using the quantum regression theorem , we obtain from here the following equation for two - time correlation functions @xmath158 where @xmath159 @xmath160 with the initial conditions defined by the steady state @xmath161 in the absence of driving at @xmath6 and @xmath7 the steady states give @xmath162 and @xmath163 , therefore @xmath164 and @xmath165 present incoherent dynamics ( fluctuations ) . solving eq . ( [ twotimes ] ) and returning to the laboratory frame , we find for @xmath166 @xmath167 where @xmath168 , @xmath169 , @xmath170 , @xmath171 . the emission spectrum is @xmath172\ ] ] in the case of @xmath173 , where @xmath174 , and @xmath175\ ] ] in the case of @xmath176 . here we have introduced a real variable @xmath177 . in the limit of weak pumping @xmath178 , the equations are simplified to the well known form for spontaneous emission of a two - level atom @xmath179 in the strong pumping limit @xmath180 , the emission spectrum @xmath181\ ] ] is split into two peaks by frequency @xmath16 and width of @xmath182 . the splitting can be explained in the rotating frame by relaxation from the level @xmath77 to the split level @xmath64 . the coplanar transmission line with the characteristic impedance @xmath183 is made by patterning a gold film deposited on a silicon substrate . in the middle of the chip , the central conductor of the waveguide is narrowed and replaced by aluminium . the latter is deposited together with the artificial atom of the flux qubit geometry shown in fig . [ fig : setup](a ) , using shadow evaporation . the experiment is performed in a dilution refrigerator at a temperature of 40 mk . [ [ transmission - and - reflection - coefficients - of - the - elastic - scattering ] ] transmission and reflection coefficients of the elastic scattering ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ we measure the complex transmission coefficient @xmath91 by a vector network analyzer . the transmission characteristics of the microwave line are calibrated with the artificial atom effectively removed : it is offset by a dc flux bias such that its transition frequency does not fall in the measurement frequency range . a schematic diagram of the experimental setup for measuring the transmission coefficient is presented in fig . [ fig : setup](b ) . to measure weak spontaneous emission on the background of top of the amplifier noise , we modulate the excitation power and use digital differentiation . the noise spectral density of the preamplifier situated at 4 k is @xmath184 w / hz , which corresponds to the effective noise temperature of the amplifier at the input @xmath185 k. a schematic diagram of the setup for measuring the spontaneous emission spectrum is presented in fig . [ fig : setup](c ) . the parameters of our device are found from the experimental curves in the following way . for calibration of the probe power at @xmath6 we measure dependence of transmission coefficients versus the probe power in the absence of pumping @xcite . for the pumping power calibration , we analyzed splittings of peaks in fig . 2(b ) and fig . the dephasing and relaxation rates are found to be @xmath186 mhz and @xmath187 mhz , correspondingly , from the dip in transmission in the limit of a weak probing @xmath17 ( similar to the black curve on fig . 3(a ) , but with a weaker probe ) . the dip width is equal to @xmath94 and the dip amplitude ( minimal transmission ) is @xmath188 . the relaxation rate @xmath189 was adjusted in the simulations to have a better agreement with the experimental curves ( particularly , the curves of fig . 3(a ) ) with neglected dephasing rates in @xmath114 and @xmath116 : we take @xmath149 and @xmath190 . the pure dephasing rates in @xmath114 and @xmath116 was neglected as they are expected to be weaker than that in @xmath83 , due to two times less steep energy bands ( @xmath191 and @xmath192 ) , in assumption that it is a result of the low frequency noise in flux degree of freedom . @xmath118 was found to be 35 mhz . the spontaneous emission spectrum calculated from eqs . ( [ sweak ] ) and ( [ ssstrong ] ) shown in fig . [ fig : semission ] well reproduces experimentally measured spectrum of fig . figures [ fig : amp ] and [ fig:2d ] show calculations of the transmission coefficient with the same values of pumping amplitudes as in figs . 3(b ) and 4 , correspondingly . in the latter calculations we used full solution of the master equation ( not the weak probing case provided by eqs . ( [ rho11])-([rho21 ] ) , because the probe amplitude @xmath193 16 mhz is not negligible comparing to @xmath83 and @xmath80 . and @xmath91 ) can be monitored . ( b ) experimental setup diagram for measuring amplification ( transmission ) . to measure the transmission coefficient @xmath91 the input signal from a network analyzer is applied to the channels input " , and amplitude and phase of an output signal are detected . the input line contains 20 db attenuator at 1 k stage and another 20 db attenuator at the base temperature to suppress 300 k blackbody radiation . the weak signal passing through the sample is then amplified using a cryogenic amplifier at 4.2 k and a room temperature amplifier . for suppression blackbody radiation coming back from the 4 k amplifier , we use two isolators at the base temperature and at the 1 k stage providing 40 db total attenuation for the backward signal . the excitation energies of the artificial atom are controlled using a coil magnetic field . ( c ) experimental setup for measuring the spectrum of spontaneous emission . we pump the atom at a high frequency corresponding transition between the ground and the second excited state and measure the emission spectrum of the first excited to the ground state using a spectrum analyzer . the weak atomic emission spectrum is extracted by subtraction of spectral curves with on " off " excitation power.,width=377 ] as presented in fig . ( b ) calculated transmission amplitude and phase as a function of the pumping amplitude @xmath16 and the probe detuning @xmath194 for the same conditions as in fig .

we report amplification of electromagnetic waves by a single artificial atom in open 1d space . our three - level artificial atom a superconducting quantum circuit coupled to a transmission line presents an analog of a natural atom in open space . the system is the most fundamental quantum amplifier whose gain is limited by a spontaneous emission mechanism . the noise performance is determined by the quantum noise revealed in the spectrum of spontaneous emission , also characterized in our experiments . the quantum amplifiers are actively used devices and most of them rely on natural intra - atomic or molecular transitions with almost untunable transition frequencies @xcite . demonstration of amplification on a single atom or molecule in open space is possible @xcite , however , extremely difficult due to another common characteristic of natural atoms ( molecules , quantum dots ) : they are relatively weakly coupled to the spatial electromagnetic waves in real experiments @xcite , in spite of theoretical feasibility of perfect coupling by careful matching of the spacial modes to the atom @xcite . an alternative approach is coupling of the atoms to a field of a high quality resonator @xcite , which has been successfully used to demonstrate lasing action on single natural @xcite and artificial @xcite atoms . in the resonators , the atom is coupled to a single mode . on the other hand , an elementary ( ultimate ) quantum amplifier avoids this limitation and can be realized on a single atom strongly coupled to a continuum of electromagnetic modes of open space . the matching problem of spacial modes of electromagnetic waves can be solved by reducing space dimensionality to a 1d @xcite . recently , the highly efficient coupling of an artificial atom to an open 1d transmission line has been achieved experimentally @xcite . we demonstrate amplification on a single three - level artificial atom coupled to a 1d transmission line . the atom is a fully controllable and tunable quantum system , with all its basic characteristics , such as energy splitting and coupling to the line , designed in accordance with our requirements . our demonstration opens the perspective of developing a new type of on - chip quantum amplifiers and other quantum devices , capable of both reproducing the known quantum - optical phenomena and realizing the novel ones , which will use the tunability , controllability and strong coupling . our device is a multi - level quantum system based on the flux qubit " geometry @xcite ( a superconducting loop with four tunnel junctions ) , coupled to a 1d transmission line through the loop - line mutual inductance @xmath0 @xcite . we limit our consideration to the three lowest energy states of the system @xmath1 ( @xmath2 ) with energies @xmath3 schematically shown in fig . [ fig : spectroscopy](a ) . the device is designed in such a way that all relevant transition frequencies of the three - level system @xmath4 ( @xmath5 ) fall within the frequency band of our transmission line and within the working range of our microwave sources , limited by 40 ghz . the system is strongly anharmonic , which prevents non - resonant transitions . the energies of the atomic levels are tuned by the external magnetic field . the transition frequencies @xmath6 , @xmath7 and @xmath8 reach their extremal values , when the induced magnetic flux in the loop @xmath9 equals to half a flux quantum ( @xmath10 ) , that is @xmath11 . our experiment is performed at the temperature @xmath12 = 40 mk , low compared to the atomic energy splitting ( @xmath13 ) , which guarantees the absence of thermal excitations . to the second excited state @xmath14 in the relaxation process @xmath15 . @xmath16 and @xmath17 are the pumping and probing rabi frequencies , which are used to express the field amplitudes . ( b ) spectroscopy of the single three - level atom . the lowest transition frequency @xmath6 is detected by measuring direct transmission . the higher transition frequency @xmath8 is found in the two - wave spectroscopy , and is seen as a bright line.,width=325 ] in the rotating wave approximation , the three - level system is described by the hamiltonian @xmath18 where @xmath19 is the atomic projection / transition operator , @xmath20 and @xmath21 . the external pumping microwave fields at frequencies @xmath22 and @xmath23 couple atomic states according to the interaction hamiltonian @xmath24,\ ] ] where @xmath25 is the dipole interaction energy for the transition @xmath26 under the influence of the field in the transmission line with the actual current given by @xmath27 = i_{ij}\cos{\omega_{ij}^d t}$ ] . here we assume that our pointlike atom is situated at @xmath28 and the waves @xmath29 with the wavevector @xmath30 propagate in the transmission line . the dipole matrix element can be presented in the form @xmath31 with the dimensionality of a magnetic flux , where the dimensionless matrix element satisfies the relation @xmath32 . the atomic dynamics is described by the standard master equation @xmath33+l[\rho]$ ] for the density matrix @xmath34 with the lindblad term @xmath35 here @xmath36 is the damping rate of the off - diagonal terms ( dephasing ) and @xmath37 is the relaxation rate between the levels @xmath1 and @xmath38 ( @xmath39 ) . in the ladder - type three - level atom @xmath40 holds . the low temperature condition suggests suppression of the excitation rates @xmath41 = 0 , @xmath42 = 0 and @xmath43 = 0 . the atom in 1d open space generates a scattered wave at frequency @xmath23 @xcite @xmath44 where @xmath45 = \rho_{ji}$ ] can be straightforwardly found in the stationary conditions ( @xmath46 ) . the transmission coefficient , found as a ratio of the resulting current @xmath47 at @xmath48 to the incident one @xmath49 , takes the form @xmath50 , and the amplification condition is @xmath51 . the solution of the master equation @xcite is simplified for the most interesting case of nearly resonant drives and fast @xmath52 relaxation ( @xmath53 ) , when the state @xmath14 remains nearly unpopulated ( @xmath54 ) . neglecting the terms @xmath55 , we obtain @xmath56 where @xmath57 , @xmath58 . in the resonance , this equation gives the standard population inversion condition for the amplification , @xmath59 , with the required pumping amplitude @xmath60 for weak pure dephasing between the ground and the second excited states ( @xmath61 ) @xcite . to characterize the energy structure of our atom we perform transmission spectroscopy by sweeping frequency of a weak probe microwave versus the flux bias @xmath62 . the transmitted wave is suppressed due to efficient resonant scattering @xcite , and reveals the transition frequency @xmath6 as a dark narrow line in @xmath63 on the lower panel of the intensity plot in fig . [ fig : spectroscopy](b ) . the higher frequency transition between states @xmath14 and @xmath64 can not be probed in the direct transmission , since the high frequency cutoff of our cryogenic amplifier ( 13 ghz ) is lower than @xmath8 . to detect @xmath8 we use two - wave spectroscopy in the following way . the probe microwave is adjusted to the minimal transmission @xmath65 , taking place at @xmath66 . simultaneously we sweep the second high frequency @xmath22 . when the transition at @xmath8 occurs , @xmath63 is increased , as the population of the level @xmath64 is reduced and , therefore , we observe a bright line in the intensity plot @xmath67 versus @xmath62 ( the upper panel of fig . [ fig : spectroscopy](b ) ) . at @xmath68 the system forms the so - called a ladder type three - level atomic system , in which the selection rule prohibits transitions between levels @xmath64 and @xmath14 due to symmetry of eigenstate wavefunctions . this is seen as the vanishing spectroscopic line in the upper panel of fig . [ fig : spectroscopy](b ) at @xmath69 ghz . to achieve population inversion , we must be able to pump the atom from the ground ( @xmath64 ) to the second excited state ( @xmath14 ) , therefore , we choose our working point at @xmath70 , slightly away from @xmath71 . driving the system at @xmath72 = 35.11 ghz , we expect the cascade relaxation @xmath73 , accompanied by photon emission at frequencies @xmath74 ghz and @xmath75 ghz . the lowest transition can be detected , since it is within our cryogenic amplifier frequency band . figure [ fig : emission](a ) shows the measured spontaneous emission spectrum under the resonant pumping at @xmath8 with an amplitude @xmath76 24 mhz , which confirms that the mechanism of the level @xmath77 population is implemented . at a weak pumping amplitude ( @xmath78 ) , the state @xmath77 population @xmath79 together with the spontaneous emission rate @xmath80 define the spectral density of the emission in one of the two possible directions via @xmath81 although in our case @xmath82 is not negligible comparing @xmath83 , the linewidth @xmath84 is still mainly determined by @xmath85 18 mhz @xcite . the intensity plot in fig . [ fig : emission](b ) shows the spontaneous emission from the atom at different pumping amplitudes @xmath16 . with increasing @xmath16 , the spontaneous emission peak broadens and then splits due to splitting of the ground state @xmath64 by the rabi frequency @xmath16 . the emission in the more general case is calculated analytically in @xcite and well describes the split emission spectral line . particularly , in the extreme case of @xmath86 each of the two split peaks is expressed as @xmath87 where @xmath88 . ) measured in the vicinity of @xmath89 = 10.96 ghz ( @xmath90 , see fig . [ fig : spectroscopy](b ) ) . ( b ) emission spectrum as a function of pumping amplitude @xmath16 . at strong pumping , the emission peak is split by @xmath16 , due to rabi splitting of the level @xmath64 , as schematically depicted in the inset . the spontaneous emission spectrum gives the noise in the system.,width=325 ] equations ( [ sw ] ) and ( [ sstrong ] ) describe spectrum of the quantum noise in the system , determined by the spontaneous emission to the transmission line . the interaction with 1d open space ( transmission line ) characterized by @xmath80 is enhanced in the field of an external resonant probe wave at the transition frequency @xmath6 , stimulating emission coherent with the external probe wave . we measure the amplitude and phase of transmission @xmath91 as a function of detuning @xmath92 under a relatively weak probe wave amplitude @xmath17 , at different pumping amplitudes @xmath16 ( fig . [ fig : amplification](a ) ) . the black curve , obtained at relatively weak pumping with @xmath93 = 3 mhz , shows a lorentzian dip with the linewidth of 40 mhz , determined mainly by the dephasing @xmath94 . the transmission is strongly modified as @xmath16 is increased . at @xmath93 = 23 mhz , the dip is completely suppressed ( blue curve ) . at stronger pumping , the amplification is observed : at @xmath93 = 40 mhz ( red curve ) the transmission exceeds one by 5% , exhibiting a clear amplification peak , and at @xmath93 = 95 mhz ( green curve ) the peak is split . note that in the amplification condition , the phase on the lower panel of fig . [ fig : amplification](a ) is inverted . the intensity plots of fig . [ fig : amplification](b ) summarize the behavior of @xmath91 versus pumping amplitude @xmath16 . versus detuning from the resonant frequency @xmath89 = 10.96 ghz at a different pumping amplitudes @xmath16 . the inset shows the amplification coefficient @xmath63 as a function of the probe amplitude @xmath17 at @xmath95 . ( b ) the intensity plot , summarizing the measurements shown in ( a ) , demonstrates the transmission amplitude ( upper panel ) and phase ( lower panel ) as a function of the pumping amplitude @xmath16.,width=325 ] the inset of fig . [ fig : amplification](a ) shows gain @xmath63 at the fixed pumping amplitude @xmath93 = 40 mhz as a function of the probe amplitude @xmath17 . in the linear amplification regime ( @xmath96 20 mhz ) , corresponding to the nearly constant @xmath63 , the gain reaches maximum of about 1.09 . interestingly , the best agreement between the calculated ( red ) curve and the experimental data ( black dots ) is obtained when pure dephasing is neglected ( @xmath97 ) . indeed , @xmath91 is insensitive to linear fluctuations of @xmath92 in the magic point " of @xmath98 . remarkably , the gain for the single atom amplifier is fundamentally limited by @xmath99 ( the corresponding power gain is @xmath100 ) , as each incident photon can stimulate not more than one emitted photon . moreover , the photon multiplication factor is always less than 2 , due to competing incoherent processes , for instance , relaxation caused by unavoidable quantum noise . the factor is reduced even more by less - than-100% population of the level @xmath77 . to calculate the maximal gain we consider the system in double resonance , without pure dephasing and with @xmath101 . in such a case for driving amplitude of the order of threshold defined by eq . ( [ thramp ] ) , the populations can be simplified to @xmath102 and @xmath103 , where @xmath104 is a square of normalized driving amplitude @xcite . with this variable eq . ( [ t ] ) becomes @xmath105 , which takes maximum @xmath106 at @xmath107 , that is @xmath108 and the corresponding populations are @xmath109 and @xmath110 . we derive the parameters of our system from the experimental data . from the dip in the transmission in the absence of pumping ( see eq . ( [ t ] ) with @xmath111 and @xmath112 ) , @xmath113 is found to be 11 mhz . in the case of negligible pure dephasing in @xmath114 ( @xmath115 and @xmath116 ( @xmath117 ) @xcite , the experimental data are in a very good agreement with theory , when we take @xmath118 = 35 mhz @xcite . amplification occurs , when the pumping amplitude exceeds @xmath119 20 mhz , found from eq . ( [ thramp ] ) consistently with our experiment . the six panels in fig . [ fig : detuning ] , each measured at different @xmath16 , show @xmath63 versus detuning from the resonances : @xmath120 ( @xmath121-axis ) and @xmath92 ( @xmath122-axis ) . amplification regions revealed as bright spots near the double resonance points , split at strong pumping ( @xmath93 = 95 mhz ) . the splitting is reminiscent of the typical anticrossing ( shown by a black dashed line ) ; however , it reveals in the over - unity transmission @xmath123 that is amplification . and @xmath92 . the pumping amplitudes @xmath16 are indicated on the panels . the black dashed line on the panel with the strongest pumping ( @xmath93 = 95 mhz ) shows the expected anticrossing spectroscopy line.,width=325 ] the amplification by a single artificial atom provides an example of an elementary quantum amplifier . however , we suggest that it can be used as a building block for practical quantum amplifiers with the noise characteristics limited by quantum noise due to spontaneous emission to the open space . the demonstrated on - chip amplifier is tunable , and its bandwidth can be selected by changing coupling to the transmission line . in a conclusion , we have demonstrated a fully controllable and tunable on - chip quantum amplifier with a single artificial atom in open 1d space . the work may open a direction of on - chip quantum electronics . this work was supported by crest - jst and mext kakenhi quantum cybernetics " . 27 natexlab#1#1bibnamefont # 1#1bibfnamefont # 1#1citenamefont # 1#1url # 1`#1`urlprefix[2]#2 [ 2][]#2 , _ _ ( , , ) . , _ _ ( , , ) . , , , , , , , * * , ( ) . , , , , , , , * * , ( ) . , , , , , * * , ( ) . , , , , , , , * * , ( ) . , , , , , , , , , * * , ( ) . , , , , , , , , , , * * , ( ) . , , , , * * , ( ) . , , , * * , ( ) . , , , , , * * , ( ) . , , , , , , * * , ( ) . , , , , , , , , , * * , ( ) . , , , , , , , , , , , * * , ( ) . , , , , , , , , , , , * * , ( ) . , , , * * , ( ) . , , , , , * * , ( ) . , , , , , , , * * , ( ) . , , , , , * * , ( ) . , * * , ( ) . , , , , * * , ( ) . , , , , , , , , * * , ( ) . , , , , , , * * , ( ) . , , , , , * * , ( ) .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Coltsville National Historical Park Act''. SEC. 2. DEFINITIONS. For the purposes of this Act: (1) City.--The term ``city'' means the city of Hartford, Connecticut. (2) Historic district.--The term ``Historic District'' means the Coltsville Historic District. (3) Map.--The term ``map'' means the map titled ``Coltsville National Historical Park--Proposed Boundary'', numbered T25/102087, and dated May 11, 2010. (4) Park.--The term ``park'' means the Coltsville National Historical Park in the State of Connecticut. (5) Secretary.--The term ``Secretary'' means the Secretary of the Interior. (6) State.--The term ``State'' means the State of Connecticut. SEC. 3. COLTSVILLE NATIONAL HISTORICAL PARK. (a) Establishment.-- (1) In general.--Subject to paragraph (2), there is established in the State a unit of the National Park System to be known as the ``Coltsville National Historical Park''. (2) Conditions for establishment.--The park shall not be established until the date on which the Secretary determines that-- (A) the Secretary has acquired by donation sufficient land or an interest in land within the boundary of the park to constitute a manageable unit; (B) the State, city, or private property owner, as appropriate, has entered into a written agreement with the Secretary to donate at least 10,000 square feet of space in the East Armory which would include facilities for park administration and visitor services; (C) the Secretary has entered into a written agreement with the State, city, or other public entity, as appropriate, providing that and owned by the State, city, or other public entity within the Coltsville Historic District shall be managed consistent with this section; and (D) prior to accepting the donation referred to in subparagraph (B), the Secretary has reviewed the plans and financial resources of the developer of the East Armory to ensure the viability of the park based on those resources. (b) Boundaries.--The park may include and provide appropriate interpretation and viewing of the following sites, as generally depicted on the map: (1) The East Armory. (2) The Church of the Good Shepherd. (3) The Caldwell/Colt Memorial Parish House. (4) Colt Park. (5) The Potsdam Cottages. (6) Armsmear. (7) The James Colt House. (c) Written Consent of the Owner.--No non-Federal property may be included in the park without the written consent of the owner. (d) Availability of Map.--The map shall be on file and available for public inspection in the appropriate offices of the National Park Service. (e) Notice.--No later than 30 days after the date on which the Secretary makes a determination under section 3(a)(2), the Secretary shall publish in the Federal Register notice of the establishment of the park. SEC. 4. ADMINISTRATION. (a) In General.--The Secretary shall administer the park in accordance with-- (1) this Act; and (2) the laws generally applicable to units of the National Park System, including-- (A) the National Park Service Organic Act (16 U.S.C. 1 et seq.); and (B) the Act of August 21, 1935 (16 U.S.C. 461 et seq.). (b) State and Local Jurisdiction.--Nothing in this Act enlarges, diminishes, or modifies any authority of the State, or any political subdivision of the State (including the city)-- (1) to exercise civil and criminal jurisdiction; or (2) to carry out State laws (including regulations) and rules on non-Federal land located within the boundary of the park. (c) Cooperative Agreements.-- (1) In general.--The Secretary may enter into cooperative agreements to carry out this Act. (2) Right of access.--A cooperative agreement entered into under paragraph (1) shall provide that the Secretary, acting through the Director of the National Park Service, shall have the right of access at all reasonable times to all public portions of the property covered by the agreement for the purposes of-- (A) conducting visitors through the properties; and (B) interpreting the properties for the public. (3) Changes or alterations.--No changes or alterations shall be made to any properties covered by a cooperative agreement entered into under paragraph (1) unless the Secretary and the other party to the agreement agree to the changes or alterations. (4) Conversion, use, or disposal.--Any payment by the Secretary under this subsection shall be subject to an agreement that the conversion, use, or disposal of a project for purposes contrary to the purposes of this section, as determined by the Secretary, shall entitle the United States to reimbursement in an amount equal to the greater of-- (A) the amounts made available to the project by the United States; or (B) the portion of the increased value of the project attributable to the amounts made available under this subsection, as determined at the time of the conversion, use, or disposal. (5) Matching funds.-- (A) In general.--As a condition of the receipt of funds under this subsection, the Secretary shall require that any Federal funds made available under a cooperative agreement shall be matched on a 1-to-1 basis by non-Federal funds. (B) Form.--With the approval of the Secretary, the non-Federal share required under subparagraph (A) may be in the form of donated property, goods, or services from a non-Federal source, fairly valued. (d) Collections.--The Secretary may enter into a written agreement with the State of Connecticut State Library, Wadsworth Atheneum, the Colt Trust, or other public entities, as appropriate, to gain appropriate access to Colt-related artifacts for routine display in the East Armory or within other areas of the park to enhance the visitor experience. (e) Acquisition of Land.--The Secretary is authorized to acquire land and interests in land by donation, purchase with donated funds, or exchange, except that land or interests in land owned by the State or any political subdivision of the State may be acquired only by donation. (f) Technical Assistance and Public Interpretation.--The Secretary may provide technical assistance and public interpretation of related historic and cultural resources within the boundary of the historic district. (g) No Use of Condemnation.--The Secretary may not acquire by condemnation any land or interest in land under this Act or for the purposes of this Act. (h) No Buffer Zone Created.--Nothing in this Act, the establishment of the park, or the management plan for the park shall be construed to create buffer zones outside of the park. That activities or uses can be seen, heard, or detected from areas within the park shall not preclude, limit, control, regulate or determine the conduct or management of activities or uses outside of the park. SEC. 5. MANAGEMENT PLAN. (a) In General.--Not later than 3 fiscal years after the date on which funds are made available to carry out this Act, the Secretary shall complete a management plan for the park in accordance with-- (1) section 12(b) of the National Park Service General Authorities Act; and (2) other applicable laws. (b) Cost Share.--The management plan shall include provisions that identify costs to be shared by the Federal Government, the State, and the city, and other public or private entities or individuals for necessary capital improvements to, and maintenance and operations of, the park. (c) Submission to Congress.--On completion of the management plan, the Secretary shall submit the management plan to-- (1) the Committee on Natural Resources of the House of Representatives; and (2) the Committee on Energy and Natural Resources of the Senate.

Coltsville National Historical Park Act - (Sec. 3) Establishes the Coltsville National Historical Park as a unit of the National Park System in Connecticut. Delays establishment of the Park until specified conditions have been met, including that: (1) Connecticut, the city of Hartford, or private property owner, as appropriate, has entered into a written agreement with the Secretary of the Interior to donate at least 10,000 square feet of space in the East Armory; and (2) the Secretary has entered into a written agreement with the state, city, or other public entity, as appropriate, which provides that land owned by such an entity within the Coltsville Historic District shall be managed consistent with this Act. Authorizes the Park to provide interpretation and viewing of specified sites, including the East Armory and Colt Park. Prohibits the inclusion of any non-federal property in the Park without the owner's written consent. (Sec. 4) Declares that nothing in this Act enlarges, diminishes, or modifies any authority of the state (including the city) to: (1) exercise civil and criminal jurisdiction; or (2) carry out state laws (including regulations) and rules on non-federal land located within the boundary of the Park. Authorizes the Secretary, to carry out this Act, to enter into cooperative agreements subject to specified terms, including right of access to conduct visitors through and interpret the properties for the public. Bars any changes or alterations to any properties covered by such an agreement unless the Secretary and the other party to the agreement agree to them. Subjects any payment made by the Secretary to an agreement that conversion, use, or disposal of a project for purposes contrary to the purposes of this Act shall entitle the United States to reimbursement. Requires any federal funds under such an agreement to be matched on a one-to-one basis by non-federal funds. Authorizes the Secretary of the Interior to enter into a written agreement with the Connecticut State Library, Wadsworth Atheneum, and the Colt Trust, or other appropriate public entities to gain access to Colt-related artifacts for routine display in the East Armory or within other areas of the Park. Authorizes the Secretary to acquire lands and interests in land by donation, purchase with donated funds, or exchange, except that lands or interests in land owned by the state or any political subdivision of the state may be acquired by donation only. Prohibits the Secretary from acquiring by condemnation any land or interest in land under this Act or for the purposes of this Act. Declares that nothing in this Act, the establishment of the Park, or the management plan for the Park shall be construed to create buffer zones outside of the Park. (Sec. 5) Requires the Secretary to complete and submit to Congress a management plan for the Park. Requires the management plan to identify the costs to be shared by the federal government, the state, the city, and other public or private entities or individuals for necessary capital improvements to, and maintenance and operations of, the Park.