text:
Molecular Evidence Of Transplacental (Vertical) Route Of Transmission Of African Swine Fever In Foetus Of Pig: A Case Report
J Antiabong, O Owolodun, O Adefalujo, B Yakubu, M Ogedengbe, D Shamaki
J Antiabong, O Owolodun, O Adefalujo, B Yakubu, M Ogedengbe, D Shamaki. Molecular Evidence Of Transplacental (Vertical) Route Of Transmission Of African Swine Fever In Foetus Of Pig: A Case Report. The Internet Journal of Veterinary Medicine. 2006 Volume 2 Number 2.
African Swine Fever (ASFV) DNA was detected in the Placenta, and organs of fetuses of a sacrificed sow using the polymerase chain reaction technique.
These findings suggest a transplacental (vertical) route of transmission of ASFV in the pathogenesis of African swine fever in foetus of pig and calls for attention considering its epizootiological potential.
African swine fever is the only member of the newly named Asfarviridae whose genomic organization and cytoplasmic replication is similar to that of poxviridae (Salas, 1999). The genomic size of ASFV varies between 170kb and 190kb with variable regions which contains at least five multigene families (vinuela, 1985;costa, 1990).
The disease was first detected in Kenya in 1910 (Montgomery, 1921) and occurred outside Africa for the first time in Lisbon (Portugal) in 1957 (Manso Ribeivo
As the only known DNA arbovirus it cycles between ornithodorous ticks and wild pig populations (Warhogs and Bush Pigs) in Sub-Saharan Africa (Wilkinson, 1984). ASFV can be transmitted by contact as the virus is present in sufficient amounts in secretions and extractions. The virus is very stable in the blood and faeces of infected animals. Airborne transmission over short distances can also occur (Salas, 1999).
The placenta is the obvious route for passage of infectious agent from mother to the offspring and for this to occur the virus must be present in the blood of the animal at the right stage of gestation and must reach the placenta and then the foetus. Transplacental infection has been reported for animal diseases such as hog cholera, porcine parvovirus, mucosal disease and equine infectious anaemia (Mims, 1981).
In an experimental infection of pregnant sows,ASF virus was recovered from foetal placenta, amniotic fluid and heart blood with specific immunoflorescence present only in the placenta tissues (Schlafer and Mebus,1987) suggesting the possibility of transplacental infection of the foetus. In this study we show a PCR evidence of a natural transplacental infection of the foetus by the African swine fever virus.
Materials And Methods
Source of Samples
Tissue samples were collected aseptically from internal organs (liver, heart, kidney, lungs) and placenta of fetuses removed from a sacrificed pregnant sow that belonged to a piggery that recorded mortality of pigs of all ages, recumbence, anorexia, varying degrees of diarrhea, reddening of skin of affected pigs. Liver tissue was collected from the sow.
0.5g of each tissue sample was homogenized using Ultra Turrax T8 (Ikawerke®) 2mls of phosphate buffer saline (PBS) was added to each of the homogenate and then short spinned at 12,000rpm for 20 seconds in microcentifuge tubes (Eppendorf®) to obtain the supernatant which contains the virus.
Genomic DNA Extraction
The genomic DNA was extracted from 100µl of the supernatants using the Tripure reagent (Roche®) according to the manufacturer's instruction. Extracted DNA was then transferred into a clean, nuclease free microcentrifuge tubes and stored at -200C for further analysis.
A diagnostic PCR was performed using 3.0µl template DNA extract in a total reaction mix of 25µl. The reaction mix included 14.5µl at nuclease free water (Promega ®), 4.5µl Dynazyme buffer (1x10mM Tris-HCl pH8.8, 1.5mM MgCl2,50mM Kcl, 0.1% Triton x – 100) Promega ®), 0.5µl dNTP (10mM nucleotide mix) (Promega®), 20pMol of primers PAS1 ( sense) S1 – ATG GAT ACC GAG GGA ATA GC-31 and PAS2 (anti sense) S1 – CTT ACC GAT GAA AAT GAT AC – 31 (GIBCO brl®) which amplifies a 278bp fragment of the VP72 gene of ASFV genome, 0.5µl of Tag.DNA polymerase (Roche®). 20µl of mineral oil (Sigma®) was added to prevent evaporation.
Amplification of target DNA sequence was carried out in a cyclogene thermal cycler (Techne®) at initial denaturation of 940C for 15s followed by 30 cycles of thermal denaturation (940C for 15s), reannealing (620C for 15s), extension (720C for 15s), and a final incubation at 720C for 15s to complete the extension phase of the reaction.
8.0µl each of the amplicons (mixed with 2.0µl of 0.25% orange G Loading buffer (Promega ®) were fractionated in a 1.5% Agarose (Sigma ®) gel using 1xTBE (Tris – Borate – EDTA) butter (Promega®) to which 5µl (1µg/1µl) ethidium bromide (Promega ®) was added. 5.0µl of 1kb molecular weight marker (Promega ®) was also fractioned along side the amplicons Electrophoresis was at a constant voltage of 80volts for 50minutes.
The result was visualized and photographed over an ultraviolet light source using a T2202 Polaroid Camera (Sigma®).
PCR analysis and electrophoresis of DNA extracted from the tissues of foetal liver, lung, and Placenta and liver of the pregnant sow detected bands which co-migrated with the positive test control (A 287bp PCR confirmed ASF viral DNA from onderspoort veterinary institute, South Africa) corresponding to the 278bp fragment of the VP72 gene which encodes a major capsid protein in the ASFV genome.
These samples were considered positive for the presence of ASFV DNA. DNA extracts from the heart and kidney tissues were not amplified nor co-migrated with the positive test control and therefore indicated the absence of ASFV DNA in these tissues Fig 1.
Lane 1: 1Kb marker. Lane 2: liver of pregnant sow. Lane 3: Foetal liver. Lane 4: Foetal placenta, Lane 5: Foetal Kidney, Lane 6: Foetal heart, Lane 7: Foetal Lungs. Lane 8: Negative control. Lane 9: Positive control
The Presence of ASFV DNA in the placenta and foetal organs of pig suggests a natural Transplacental (vertical) route of infection in the pathogenesis of the disease. As observed, ASFV DNA from the liver tissue of the sow co-migrated with that of the foetus as well as the positive test control. This indicates an active stage of infection in the sow which also presented clinical signs of African swine fever infection before being sacrificed.
No ASFV DNA was detected in the heart and kidney tissues of the foetus. This could be due to the lack of receptors for viral attachment in the pathogenesis of the virus, in these organs at the time of infection. It has been shown that the presence of receptors is necessary for a productive infection of ASFV (Salas, 1999).
Pigs which recover from ASFV infection are known to be carriers and this serves as a factor in the persistence of the virus. Vertical transmission sometimes play a central role in the epizootiology of infectious diseases, for instance, in cases where antigens are presented to the foetus before development of immune responses and this, regards as self rather than non-self and immune responses to these particular antigens would therefore be minimal. This might enable an infectious agent to persist indefinitely in the animal as seen in the case of mice that carry lymphocytic choriomeningitis (LCM) virus (Burnet and Fenner, 1949).
Whether this principle is also applicable in the persistence of ASFV infection in pigs is yet to be proven. Schlafer and Mebus (1987), recorded abortion in sows experimentally infected with ASFV. However, in a situation where the virus persists in the foetus after being farrowed a carrier status could result.
Therefore, the phenomenon of transplacental (vertical) transmission of ASFV further poses a challenge in the epizootiological control of African swine fever.
The authors acknowledge the executive director, National Veterinary Research Institute for permission


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- (of a young farm animal) fed by hand；(of a person) fat.
- a calf, in particular one which is fed by hand
- feed (a young animal) by hand
- 1. Australian (of a young farm animal) fed by hand there's always a special bond with the animals that have been poddy calves or lambs
- 2. dialect (of a person) fat.
- 1. a calf, in particular one which is fed by hand poddies were a lot of work because of the constant feeding
- 1. feed (a young animal) by hand poddying the calves was to be my job, so Fred told me
- feed (a young animal) by hand: I hope they're having success with poddy-rearing the foal
- a person who steals unbranded cattle: the cattle were forced on to the hills, where they were easy picking for the old poddy dodger
- steal (unbranded cattle): he also made fences, poddy-dodged cattle and farmed

source: openbmb/Ultra-FineWeb


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What: The Atomium
Where: Square de l'Atomium, B-1020 Brussels, Belgium
In northern Brussels a structure named 'Europe's most bizarre building' is a permanent reminder of the Cold War's utopian vision of the future. The Atomium was constructed for Expo 58, the Brussels World's Fair of 1958, and was originally intended only to survive the months of the Fair. But such was the popularity of this unusual part-building part-sculpture that over half a century later it remains the Belgian capital's most popular tourist destination.
The 335ft-high stainless steel building was designed by engineer André Waterkeyn with architects André and Jean Polak. The shape represents a single molecule of iron magnified 165 billion times. Five of its nine spheres house permanent and temporary exhibition spaces, while the connecting tubes enclose escalators and staircases. The top provides a panoramic view where on a clear day visitors can see as far as Antwerp.
Built at the height of the Cold War, when scientific developments were at the forefront of confrontations between competing nations, the Atomium recalls the idealistic dreams of the Space Race and ambitions on both sides of the Iron Curtain for an ultra-modern and super-technological future.
Images: Exterior and interior of The Atomium, designed by André Waterkeyn, André Polak and Jean Polak, 1958. Photos courtesy Shed Expedition


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Capillary Chromatography - The Flame Ionization Detector
Detectors for Use with Capillary Columns
Detectors for use with capillary columns must have high sensitivities due to the limited sample size that can be used whith such columns. In addition, due to the very small peak volumes produced by the column, the sensing volume must also be extremely small. As the flame ionization detector (FID) is mass sensitive as opposed to concentration sensitive (see book 4 of this series for the meaning of mass and concentration sensitivity) the dilution by hydrogen does not effect the detector response. Thus, the FID has both the high sensitivity and the small sensor volume that is necessary and is, consequently, ideal for use with capillary columns. The nitrogen phosphorous detector (NPD) is also appropriate for capillary columns (the function of which is very similar to that of the FID) for the same reason. The micro-argon detector employs a scavenger flow which also, in effect, reduces the sensor volume, so this detector can also be used with capillary columns. The FID and the NPD detector will be described here. For a more detailed treatment of GC detectors see book 4 of this series.
The Flame Ionization Detector
The FID, invented by Harley and Pretorious (6), and separately by McWilliams and Dewer (7), evolved from the Heat of Combustion Detector developed by Scott (8). The FID operates in the following manner. Hydrogen is mixed with the column exit gas (which may be helium, hydrogen or any other appropriate gas) and then burnt at a small jet which is situated inside a cylindrical electrode system.
Figure 13. The Flame Ionization Detector


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LINE CREEK VALLEY, Wyo. (AP) — A gas well blowout in the shadow of Yellowstone National Park spewed a cloud of explosive natural gas, forced evacuations for miles around and polluted the drinking water — and the people who live in Wyoming's Line Creek Valley still wonder four years later if their lives will return to normal.
Days of panic after the Aug. 11, 2006, blowout at the well have been replaced by lingering uncertainty about a pollution plume 225 feet underground.
Now Windsor Energy is applying to drill a new well even though the blowout's cause, to this day, remains a mystery.
Last year's Deepwater Horizon disaster focused international attention on offshore blowouts. But they happen more often onshore, with dangerous effect: release of toxic gases, spills of oil and plumes of groundwater pollution.
© Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

source: HuggingFaceFW/fineweb-edu


Dyeing & Weaving
Japanese page
Weave (p. 143 )
1. Produced in Taketomimachi(Taketomi Island) Yaeyamagun, Okinawa Prefecture.
2. Characteristics: Short width sashes, called "Minsa" with 8.5 cm width and 230 cm length. Cotton fabric of warp rib weave. On both sides of the sash, stripes are woven in which one stripes consists of a mass of short horizontal lines. It is called "Mukade(centipede) Moyo(pattern)." On another stripe between some others, the pattern of 5 and 4 square dots is woven in after one another.
3. Uses: Sashes, neckties.
4. History: The origin is not clear but "Minsa" is closely related to the act of "Kayoi Kon"(court paying) which has been practiced here until lately. When a man visited a woman at her house, the woman presented this sash to the man with an endearing heart, wishing "Itsu(whose sound means ﾔfiveﾕ) Yo(ﾔfourﾕ) mademo" ("Love me forever"). An allegory is expressed in the sash. In the 2 vertical stripes, a womanﾕs wishes are put in, requesting that the man be constant and faithful. The stripes, in which a mass of horizontal lines are woven, are called "centipede pattern" and are said to express a wish for the man to visit her frequently. Today, not only the indigo dyed "Minsa," but other multi-colored sashes, table cloths and pouches are produced.
Dyeing Method
The Minsa, which is produced in Kobama Island, near Taketomi Island, is called "Ki Ai Zome." "Ki Ai" is an Indian indigo which used to grow much in the Island. Cultivated indigo, however, is used today. The steps in "Ki(literally, tree) Ai(indigo) Zome(dyeing)" are as follows:
(1) Leaves of "Ki Ai" are put in the vat with lime water.
(2) Fermentation starts in four or five days. Skimming of the supernatant liquid. Moving the settled indigo into another vat.
(3) The indigo is again fermented. Threads are dipped and dyed here.


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Bloy, Léon (lāôNˈ blwä) [key], 1846–1917, French writer. A Roman Catholic and a social reformer, Bloy wrote violent and vituperative attacks on religious conformism and bitter portraits of his life and friends. His works decry cruelty and injustice, and their fervor made them influential in Europe. They include the autobiographical novels Le Désespéré [the hopeless one] (1886) and La Femme pauvre (1897, tr. The Woman Who Was Poor, 1939); Salut par les Juifs (1892), a tribute to the Jews; and a vast body of correspondence.
See studies by M. R. Brady (1969) and R. Heppenstall (1969).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Social Reformers


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tree-equal tree-1 tree-2 &key test test-not => generalized-boolean
Arguments and Values:
test---a designator for a function of two arguments that returns a generalized boolean.
test-not---a designator for a function of two arguments that returns a generalized boolean.
generalized-boolean---a generalized boolean.
tree-equal tests whether two trees are of the same shape and have the same leaves. tree-equal returns true if tree-1 and tree-2 are both atoms and satisfy the test, or if they are both conses and the car of tree-1 is tree-equal to the car of tree-2 and the cdr of tree-1 is tree-equal to the cdr of tree-2. Otherwise, tree-equal returns false.
tree-equal recursively compares conses but not any other objects that have components.
The first argument to the :test or :test-not function is tree-1 or a car or cdr of tree-1; the second argument is tree-2 or a car or cdr of tree-2.
(setq tree1 '(1 (1 2)) tree2 '(1 (1 2))) => (1 (1 2)) (tree-equal tree1 tree2) => true (eql tree1 tree2) => false (setq tree1 '('a ('b 'c)) tree2 '('a ('b 'c))) => ('a ('b 'c)) => ((QUOTE A) ((QUOTE B) (QUOTE C))) (tree-equal tree1 tree2 :test 'eq) => true
Side Effects: None.
Affected By: None.
The consequences are undefined if both tree-1 and tree-2 are circular.
equal, Section 3.6 (Traversal Rules and Side Effects)
The :test-not parameter is deprecated.


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The purpose of this blog is to discuss ways that a veteran without a 100% VA disability rating can use Total Disability/Individual Unemployability (TDIU) to achieve the same results. Although many veterans seek to qualify for a 100% disability rating based on one or more disabilities, the reality of reaching this goal is quite difficult based on the VA's rating schedule. The reason for this difficulty is the fact that many disabilities do not have ratings criteria that reaches 100%, and for those disabilities that can be rated at 100%, the requirements to qualify are usually extremely narrow and subjective.
The formula used by the VA when combining more than one rating also makes the likelihood of reaching a 100% rating very difficult. For example, a veteran with one disability rated at 70% is considered by the VA as being 30% "non-disabled." Any further disability ratings affects only the remaining 30% portion of the veteran. Therefore a 70% rating combined with a 70% rating is not a 140% rating. It is 70% + 21% (30 X.70) = 90% (91% is rounded down to 90%). As one can see, as a veteran nears a 100% rating it will take higher and higher additional ratings to increase the veterans overall rating even by 1% on the combined scale.
Because a 100% schedular rating is so difficult to reach for most veterans, an alternative mechanism called TDIU is also used by the VA. TDIU helps veterans, who are no longer employable due to their service connected disabilities, to achieve a 100% service connected rating, even though their schedular disability rating is lower than 100%.
Although most disabled veterans have heard of TDIU, there exists many misconceptions about TDIU and how to utilize TDIU effectively. The most common misunderstanding about TDIU is that it is a separate claim. In fact, TDIU can be considered in conjunction with an underlying claim for an increased evaluation. An additional misconception is that TDIU only applies to individuals with particular disabilities or rating levels.
When determining TDIU, the VA can only consider service connected disabilities and their effect on a veteran's ability to obtain and maintain gainful employment. Any disability, no matter how severe, which is not service connected cannot be a basis for TDIU. Besides being determined solely upon service connected disabilities, TDIU traditionally can be considered only if:
- The veteran has one service connected disability rated at 60% or higher; or
- If the veteran has a combined service connected disability rating of 70% and at least one disability rated at 40%.
When considering the single disability rating requirement of 60% or 40% as discussed, the VA will often miss the fact that many types of disabilities can be grouped together and treated as a single disability. For example, disabilities to both arms or both legs can be combined and treated as a single disability for purposes of TDIU. In addition, multiple disabilities that arose out of a single disease or accident can also be combined into a single disability for the purpose of TDIU.
Beyond the "schedular" application of TDIU, which requires ratings of 60% for a single disability and 70% for multiple disabilities (at least one disability rated at 40%), VA regulations also provide for consideration of "extraschedular" TDIU, when there is a single disability that does not meet the minimum rating requirements but the veteran is still unable to maintain gainful employment. For example, a veteran who suffers a single disability of the back may have a rating of 40%. This rating on its own would not reach the rating requirements for schedular TDIU; however, this veteran may still not be able to stand, sit or walk for sufficient amounts of time to allow the veteran to maintain gainful employment. Because the rating criteria does not allow for a higher rating for the back, and the veteran cannot maintain gainful employment, the regulations provide an extraschedular mechanism for the VA to grant TDIU. In this example, the veteran does not meet the minimum rating requirement for traditional TDIU, however, because a veteran cannot maintain gainful employment due to a service connected disability, the VA may grant TDIU if the veteran files for a rating increase and proves he is unemployable.
The bottom line is that veterans have alternative pathways of achieving a 100% disability rating. Many times the VA does not adequately consider these alternatives and it is important that denied claims are appealed and the claim is developed properly with evidence showing how the veteran's disabilities prevent the veteran from obtaining and maintaining gainful employment. If a veteran cannot work due to one or more service connected disabilities, the veteran is entitled to Total Disability/Individual Unemployability (TDIU).


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Researchers from NASA's Goddard Space Flight Center (GSFC) and several other government and academic institutions have created four new supercomputer simulations that for the first time combine their mathematical computer models of the atmosphere, ocean, land surface and sea ice. These simulations are the first field tests of the new Earth System Modeling Framework (ESMF), an innovative software system that promises to improve and accelerate U.S. predictive capability ranging from short-term weather forecasts to century-long climate change projections.
Image: ESMF enables a forecaster to bring a computer model of the atmosphere from a different organization to the U.S. operational weather forecasting system as an alternative. These images depict wind and temperature data. This field test is a collaboration among NASA's Goddard Space Flight Center (GSFC), the National Center for Atmospheric Research (NCAR), and the National Centers for Environmental Prediction (NCEP). Credit: Carlos Cruz, Shujia Zhou, Northrop Grumman IT/GSFC; Arlindo da Silva, GSFC; Erik Kluzek, NCAR; Weiyu Yang, NCEP.
Although still under development, many organizations and research institutions are starting to adopt ESMF. Under a partnership, groups from NASA, the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA), the Department of Energy (DOE), the Department of Defense and research universities are using ESMF as the standard for coupling their weather and climate models to achieve a realistic representation of the Earth as a system of interacting parts, unifying much of the modeling community. ESMF makes it easier to share and compare alternative scientific approaches from multiple sources, uses remote sensing data more efficiently and eliminates the need for individual agencies to develop their own coupling software.
"The development of large Earth system applications often spans initiatives, institutions and agencies, and involves the geoscience, physics, mathematics and computer science communities. With ESMF, these diverse groups can leverage common software to simplify model development," said NASA ESMF principal investigator Arlindo da Silva, a scientist in GSFC's Global Modeling and Assimilation Office.
NASA's Earth-Sun System Technology Office/Computational Technologies Project funds the field tests and overall ESMF development. The partners on the field tests are DOE's Los Alamos National Laboratory (LANL), the Massachusetts Institute of Technology (MIT), NASA's Jet Propulsion Laboratory, NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) and National Centers for Environmental Prediction (NCEP), NSF's National Center for Atmospheric Research (NCAR) and the University of California, Los Angeles (UCLA).
The newly completed field tests, known as interoperability experiments, show that this new approach in coupling models can be successful. For instance, temperature and wind outputs are similar around the globe when ingesting data into an NSF-NASA atmosphere model as they are for the atmosphere model used operationally by NOAA. Although most of the experiments would require exhaustive tuning and validation to be scientifically sound, they already show that ESMF can be used to assemble coupled applications quickly, easily and with technical accuracy.
"These interoperability experiments illustrate the role ESMF can play in integrating the national Earth science resources," da Silva said. "Using existing data assimilation technology from NCEP, the finite-volume Community Atmosphere Model, or fvCAM, was able to ingest conventional and satellite observations, a capability that could open the door to using the fvCAM for weather as well as climate prediction." The fvCAM, which includes land surface capabilities, was developed by NCAR, with key components from GSFC.
The second experiment combines NCEP's data assimilation technology with the Aries atmosphere model originally developed by the NASA Seasonal-to-Interannual Prediction Project. Aries is typically coupled with an ocean model to run experimental forecasts of phenomena such as El Niño and its effects on precipitation. Among additional advantages, the two field tests enable the intercomparison of systems for satellite data assimilation.
The coupled experiments have many other potential applications. The third experiment, combining a GFDL atmosphere-land-ice model with an MIT ocean-sea ice model (known as MITgcm), may ultimately bring new insights into ocean uptake of carbon dioxide and other important atmospheric gases and how this process affects the climate.
In an early independent adoption of ESMF technology, UCLA researchers have successfully coupled their Atmospheric General Circulation Model to the MITgcm for the first time and updated a previous coupling to the LANL Parallel Ocean Program model. They made experimental predictions of the El Niño/Southern Oscillations with the coupled models using initial states provided by JPL's Estimating the Circulation and Climate of the Ocean (ECCO) project. These preliminary results validate ESMF performance in terms of scientific fidelity and support the importance of ECCO products for improving short-term climate forecasts.
Demonstrations of the software and the field tests are taking place at the 4th ESMF Community Meeting at MIT in Cambridge, Mass., July 20–22. Reaching beyond the ESMF partnership, the research team releases the software to the scientific community via the Internet. NCAR, home of the core implementation team, is scheduled to release ESMF Version 2.2.0 this month.
Source: NASA/Goddard Space Flight Center--EOS Project Science Office
Explore further: Cassini imaging lead hopes for planet-wide celebration of the Pale Blue Dot


Botanical name: Ozothamnus leptophyllus
Family name: Asteraceae
tauhinuB2.jpg Overview
Tauhinu (formerly known as Cassinia leptophylla) is a perennial scrub weed species which is native to New Zealand. It looks similar to manuka, but is not as widespread, causing problems mainly in eastern districts of New Zealand only, from Wairoa down to Otago. As with most scrub weed species, tauhinu is generally a problem in hill country pastures, where it gradually becomes denser in paddocks if good grazing pressure and pasture competition cannot be maintained. Although the correct spelling for this weed is shown above, many farmers incorrectly call it tawhini (pronouncing it as tar-winny). As with manuka, tauhinu is also often grown in people's gardens as an ornamental.
Tauhinu flower heads Distinguishing features
Tauhinu has small leaves just like manuka. However, it has several differences to manuka. Manuka leaves tend to have a pointed tip, whereas the leaves of tauhinu are rounded. Also, the underneath of tauhinu leaves are whitish in colour, though often this is not readily evident as the leaves can curl so the underneath is difficult to see. Manuka has colourful pink flowers whereas tauhinu produces seed-heads with lots of fluffy pappus sticking out of them, as do many other Asteraceae weeds, allowing seeds to be blown in the wind. The shrubs grow to about 2 m in height.
tauhinuB3.jpg Control
Tauhinu has pliable stems, making it more difficult than some scrub species to flatten using machinery. It is also not particularly susceptible to herbicides, being resistant to glyphosate. However, it can be controlled by metsulfuron (eg Escort, Answer), triclopyr (eg Grazon) and triclopyr/picloram (eg Tordon Brushkiller).


Microsurge Electrical Pollution (Dirty Electricity)
IBE 221.2
MEP is a ubiquitous problem in modern civilization. It is present everywhere, both inside and outside the home. Major polluters are utility power, switch mode power supplies (electronics), AMI meters (due to conducted high-frequency pulsed radiation), fluorescent lights (including CFLs), variable speed motors (many "smart" appliances), inverters (especially solar and cell antennas), and ground current (especially rural areas). It is a highly erratic electric field.
Topics include a brief history of micro surge electrical pollution (MEP), four distinct points of view, and microsurge electrical pollution's etiology, health effects, measurement methods, mitigation.
This course conveys 15 Building Biology Continuing Education Units (CEUs).
Tuition: $115.00
Download a free preview of this course.


text:
Patent application title: Continuous Furnace with Coupled Laser for the Surface Treatment of Materials
Luis Carlos Estepa Millan (Zaragoza, ES)
German Francisco Fuente Leis (Zaragoza, ES)
Consejo Superior De Investigaciones Cientificas
IPC8 Class: AB23K2600FI
Class name: By arc using laser method
Publication date: 2009-09-17
Patent application number: 20090230105
The present invention relates to a continuous kiln coupled to a laser by a
conventional optical means that allows for surface treatment of a part,
such that it is possible to achieve temperatures of up to 3000° C.
on the surface of the part while the remainder of the part is at a
substantially lower temperature. The part in the kiln is heated to a
temperature on the order of 500° C. and a laser beam bundle is
applied to the part via an opening in the kiln. The laser beam scans a
line perpendicular to the direction of movement of the part such that the
entire surface is scanned by means of the mechanical advance of the part.
The scanning may extend beyond the lateral ends of the part. The kiln may
comprise different zones with independent temperature controls for
successfully achieving desired values, both for heating and cooling.
6. A system for treating a surface of a material, comprising:a continuous kiln, comprising a means for conveying a material through the kiln, and an enclosure having an exterior top surface comprising an inlet, wherein the material has a top surface and side edges; anda laser positioned such that a laser beam emitted by the laser enters through the enclosure inlet and sweeps across the top surface of the material while the material moves through the kiln.
7. The system of claim 6, wherein the continuous kiln comprises two or more zones in the enclosure, wherein each zone is maintained at a different temperature.
8. The system of claim 7, wherein the zones in the enclosure comprise:a first zone located before exposure to the laser beam, wherein the temperature is less than the temperature of the surface of the material during contact with the laser beam, and less than the melting point of the material;a second zone located where exposure to the laser beam occurs;a third zone located after exposure to the laser beam; anda fourth zone located after the third zone,wherein the temperature declines between the third zone and the fourth zone at a controlled rate.
9. The system of claim 6, wherein the material is conveyed in a direction perpendicular to the direction of the emitted laser beam.
10. The system of claim 6, wherein the enclosure inlet and the enclosure are made from the same material, and wherein the enclosure inlet protrudes from the exterior top surface of the enclosure at an angle of less than 90.degree..
11. The system of claim 6, wherein the enclosure is thermally insulated.
12. The system of claim 6, wherein the temperature of the top surface of the material is less than or equal to 3000.degree. C.
13. The system of claim 6, wherein the laser beam sweeps in a pendular motion over a fixed line as the material is conveyed through the kiln.
14. The system of claim 6, wherein the sweep of the laser beam surpasses the side edges of the material.
15. The system of claim 6, wherein the laser is selected from CO2 lasers, diodes, and Nd lasers.
16. The system of claim 6, wherein the laser beam has a wavelength ranging from 0.8 μm to 1.1 μm.
17. The system of claim 6, further comprising a plane lens to offset decreased laser beam power at the side edges of the material.
18. The system of claim 6, further comprising a means for heating the area inside the enclosure.
19. The system of claim 18, wherein the means for heating the area inside the enclosure is selected from electrical elements, gas, and fuel combustion.
20. The system of claim 6, further comprising:a means for generating ultraviolet to infrared radiation; anda means for altering the position of the emitted laser beam.
21. The system of claim 20, wherein means for generating ultraviolet to infrared radiation comprises a radiation generation and emission cavity.
22. The system of claim 6, further comprising a means for controlling the direction of the laser beam emitted by the laser.
23. The system of claim 22, wherein the means for controlling the direction of the emitted beam comprises an opto-mechanical configuration,wherein the opto-mechanical configuration comprises a galvanometer system or a system of lens and mirror combinations that controllably oscillate, and adjusts the direction and shape of the laser beam to desired settings.
24. The system of claim 6, further comprising a computer having a processor, computer readable medium, and computer readable medium encoded with software configured to control the required intensity, emission time, stoppage, and movement of the radiation.
25. A method for treating the surface of a material, comprising the steps of:(a) placing a material in a continuous kiln, comprising an enclosure having an exterior top surface comprising an inlet, wherein the material has a top surface and side edges; and(b) propagating a laser beam through the enclosure inlet, such that the laser beam sweeps across the top surface of the material as it moves through the kiln.
26. The method of claim 25, wherein the sweep of the laser beam surpasses the side edges of the material.
27. The method of claim 25, wherein the laser beam sweeps in a pendular motion over a fixed line as the material is conveyed through the kiln.
28. The method of claim 25, wherein the laser beam sweeps in a direction perpendicular to the direction of the material moving through the kiln.
29. The method of claim 25, wherein the portion of the material not exposed to the laser beam has a lower temperature than the portion of the material exposed to the laser beam.
30. The method of claim 25, wherein the material passes through two or more zones in the enclosure, wherein each zone is maintained at a different temperature.
31. The method of claim 30, wherein the zones in the enclosure comprise:a first zone located before exposure to the laser beam, wherein the temperature is less than the temperature of the surface of the material during contact with the laser beam, and less than the melting point of the material;a second zone located where exposure to the laser beam occurs;a third zone located after exposure to the laser beam; anda fourth zone located after the third zone,wherein the temperature declines between the third zone and the fourth zone at a controlled rate.
This application is a U.S. national phase application under 35
U.S.C. §317 of International Patent Application No. PCT/ES07/070047
filed Mar. 6, 2007, which claims the benefit of priority to Spanish
Patent Application No. P200600560 filed Mar. 7, 2006, the disclosures of
all of which are hereby incorporated in Spanish on Sep. 13, 2007 as WO
FIELD OF THE INVENTION
The present invention related to fields involving: production of floor tiles and other industrial and technical, conventional and high performance ceramics, some of which are unattainable using current techniques; processing of refractory materials; processing of architectural and technical glass; producing coatings; and altering the surfaces of materials.
In industrial sectors, such as ceramics, where the supply of heat is essential, laser technology is capable of offering large-scale surface treatments that were previously inconceivable from the point of view of conventional technology. The present invention, by incorporating lasers into conventional treatment systems, offers benefits in terms of energy consumption and CO2 emissions that can make formerly unviable processes economically attractive and profitable, while at the same time carrying out new processes that are impossible using current techniques.
Materials have been treated using lasers virtually since the time commercial lasers came into use several decades ago. The use of lasers for cutting, marking and welding operations of an enormous variety of materials is commonplace nowadays in many industrial sectors, and there are high performance commercial systems for use in industrial environments. The reliability, flexibility and adaptability of lasers to highly productive processes, together with the other benefits that lasers provide (reduction of residues and a healthier work environment among others), and their gradual miniaturisation and increased efficiency foretell a substantial increase in their adaptation to new transformation processes in the materials industry in general.
Where the present invention is concerned, the scientific and technical background described by the state of the art is summarised as follows.
The production of ceramic materials is generally associated with high temperatures, characteristic of the particular sintering processes related to the various desired compositions, microstructures and properties thereof [Introduction to Ceramics, W. D. Kingery, H. K. Bowen, D. R. Uhlmann, Wiley, New York (1976), 2nd Edition]. For example, in the tile industry it is common for most products used for flooring and cladding to have sintering temperatures of between 1100 and 1300° C. In order to produce industrial quantities of these products, very long continuous kilns have been developed in recent decades, with the pieces supported and transferred based on the use of ceramic rollers.
The greatest advance made over this period is perhaps the development of single-firing which permits optimising and minimising the duration of the sintering process, avoiding multiple firings and allowing the piece to be decorated and consolidated in a single process [Materias Primas y Aditivos Ceramicos, L. Sanchez-Munoz


text:
Stone carving of the goddess Nike at the ruins of the ancient Greek city of Ephesus
|Goddess of victory|
|Parents||Pallas and Styx|
|Siblings||Kratos, Bia, Zelus|
|Titans and Olympians|
In Greek mythology, Nike (Greek: Νίκη, "Victory", pronounced [nǐːkɛː]) was a goddess who personified victory, also known as the Winged Goddess of Victory. The Roman equivalent was Victoria. Depending upon the time of various myths, she was described as the daughter of Pallas (Titan) and Styx (Water), and the sister of Kratos (Strength), Bia (Force), and Zelus (Zeal).
Nike and her siblings were close companions of Zeus, the dominant deity of the Greek pantheon. According to classical (later) myth, Styx brought them to Zeus when the god was assembling allies for the Titan War against the older deities. Nike assumed the role of the divine charioteer, a role in which she often is portrayed in Classical Greek art. Nike flew around battlefields rewarding the victors with glory and fame.
Nike is seen with wings in most statues and paintings. Most other winged deities in the Greek pantheon had shed their wings by Classical times. Nike is the goddess of strength, speed, and victory. Nike was a very close acquaintance of Athena, and is thought to have stood in Athena's outstretched hand in the statue of Athena located in the Parthenon. Nike is one of the most commonly portrayed figures on Greek coins.
Names stemming from Nike include among others: Nicholas, Nicola, Nick, Nicolai, Nikolai, Nicolae, Nils, Klaas, Nicole, Ike, Niki, Nikita, Nika, Niketas, and Nico.
- The shoe and sports equipment company Nike, Inc. is named after the Greek goddess Nike.
- Project Nike, an American anti-aircraft missile system is named after the goddess Nike.
- A figure of Nike with a vessel was the design of the first FIFA World Cup trophy, known also as the Jules Rimet trophy.
- Since Giuseppe Cassioli's design for the 1928 Summer Olympics, the obverse face of every Olympic medal bears Nike's figure holding a palm frond in her right hand and a winner's crown in her left.
- On the emblem of the University of Melbourne, the goddess also appears.
- She is depicted on the front of the World War II Victory Medal (United States).
- The hood ornament used by the automobile manufacturer Rolls-Royce was inspired by Nike.
- The Titanic Engineers' Memorial, Southampton depicts Nike blessing the engineers of the R.M.S. Titanic for staying at their post as the ship sank.
- Goddessnike.com (2011 [last update]). "Goddess Nike - Who is Nike? The Winged Goddess of Victory". goddessnike.com. Retrieved 24 June 2011.
- "Styx is the goddess of the underworld river Styx (water is not Nike's mother)". Theoi.com. Retrieved 2011-11-15.
- "Nike: Greek goddess of victory". Theoi.com. Retrieved 2011-11-15.
- Sayles, Wayne G. (2007). Ancient Coin Collecting II. Krause Publications. p. 149. ISBN 978-0-89689-516-4.
- Winner's medal for the 1948 Olympic Games in London, Olympic.org. Accessed 5 August 2011.
- "Picture of 2004 Athens Games Medal". Retrieved 2010-01-28.


Blender 3D: Noob to Pro/Modeling a volcano
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In this module, you will create a volcano using the proportional edit fall-off tool. You should be comfortable with deleting and adding meshes.
Adding a Plane[edit]
Delete the basic cube. Add a plane, and S cale it up by 10. Rotate it so you see it in top-view (make sure its in Orthographic view too).
Enter Edit mode and subdivide (with W ) 5 or 6 times. More subdividing will give you a "smoother" volcano, but it also needs more CPU power.
The difference between "Subdivide" and "Subdivide Multi"...
"Subdivide" divides every square in the plane into four new squares. So every time you press "Subdivide" you will have four times as many squares as before. "Subidivide Multi" will make x horizontal and x vertical lines through your existing squares, so the new number of squares is: (squares_old)*(x+1)2, whereas x is the number you enter.
Making the Mountain[edit]
In top view, select one of the points in the middle of the plane. With this point selected change to side view. Press the O , which enables the "Proportional Edit Falloff" tool in the Menu-Panel beneath the 3-D-Window. As seen in the previous tutorial Blender 3D: Noob to Pro/Mountains Out Of Molehills when you move a vertex while edit falloff is enabled, all vertices in a defined radius of the selected vertex will align with the selected vertex when its position is altered. How they are adjusted can be chosen in the tab on the right of the yellow dot. I propose using "smooth falloff".
Blender Smooth fallof.jpg
Now grab the vertex with G . You will now see a gray circle. You can change it's size with the mouse wheel. Every vertex inside this radius will be affected by the falloff. Change the size of the circle so almost the whole plane is in it.
Blender circle size.jpg
Now move the vertex a bit upwards, as seen in the picture. Optionally you can lock the z-axis to make the volcano go straight up by pressing Z .
Blender grab 1.jpg
As you can see all the other vertices will shift upward. We could keep moving this vertex at the same rate, but that would cause the plane itself to rise and bend, and that's not very good. So press LMB to apply the changes, grab the same vertex a second time and repeat the previous exercise as before, except now choose a smaller radius for the circle, about half the diameter of the plane ( G Z → scroll MMB ).
Blender grab 2.jpg
Repeat this two or three more times and you will get something like this:
Blender grab last.jpg
Forming the Crater[edit]
Now we're going to create the "hole" on the volcano. First change the falloff to "root". Grab the vertex one more time, change the size of the circle so it's more or less as seen in the picture.
Blender grab down circle.jpg
Grab this vertex down a bit, apply, grab it one more time with a smaller circle. You now should have something like this:
Blender grab down last.jpg
If yours has such a jagged border like mine, you should follow the following steps: First disable the fallout tool with O . Then select a vertex and grab it, then pull it up so it's on the same height as the other. Do this for every vertex till they're more or less the same height.
You can also select the jagged vertices and the vertices around them then press W → Smooth (Older versions: Space → edit → vertices → smooth) and this will get rid of some of the jagged edges. (I suggest using this method since this is only a basic volcano, and using Subsurf after this will make the jagged edges all but invisible anyway.)
Blender edges corected.jpg
Now TAB to get into Object mode. Add a Sub-Surf Modifier to the Mesh, set at level two ( 'Modifiers' tab → Add Modifier → Subsurf → Catmull-Clark → Levels: 2; Render Levels: 2).
Blender subsurf.jpg
Do not apply these settings yet, first we'll do a test-render. Press F12 to enter Render, after adjusting the camera. If you like your volcano you may apply the modifier, but if you have some rather nasty edges like I do, don't apply the modifier yet. We'll correct this now.
First click on the marked button to disable the subsurf-modifier in Edit-mode.
Blender disable modifier.jpg
Then enter Edit-mode. Then select the vertices on the top and pull one after another a little bit outwards, so they form a nice circle.
Optional Enhancement Method to form the circle:
I found this nifty method to help "guide" making this circle with the manual vertex manipulation.
1. Enter Object mode, we will be creating a new temporary object.
2. Center your cursor (either Shift+S->Cursor to center(if your original plane HAS NOT shifted from center of grid) or Shift+S->Cursor to Selected(if your original plane HAS shifted from center of grid), basically you want the cursor centered in your plane.
3. Once you have the cursor centered, hit Ctrl+NUM7, to bring up Bottom Ortho view. You should now see the volcano from the inside out and your slightly edged crator opening.
4. Hit Shift+A->Mesh->Circle. This will create a circle at the cursor which will also be completely centered on the crator. Slelct the circle with RMB and Scale it with S, manually increase the size until it it slightly larger than your crator opening, or however large you want the out edge to be.
5. Once your circle is the correct size, make sure you have the translate manipulator turned on, select the circle and change to Front Ortho view (NUM1). Now move the circle through and above the volcano along the Z axis (blue handle). Finally, change to Top Ortho View (NUM7).
6. While still in object mode, deselct the circle and select the plane containing your volcano. You now have a nice "guide ring" to grab your vetices to! After you have finished positioning your vertices, deselect all with an A, spin your view by holding down MMB and moving the mouse, enough to be able to pick out the circle easily without selecting the plane. Tab to object mode, select the circle again with RMB and finally delete it with X.
 - Unity user GlennC
Make circle.jpg
Once you have done this exit Edit-mode and press the "Set Smooth" Button in the Link and Materials Button. If you Render now again, it should look a lot better. (Don't worry about the color)
Blender volcano render final.jpg
Adding Magma[edit]
Let's add some "magma" using lighting.
 1. Press Shift + S and choose Cursor to Center.
 2. Press Shift + A and choose Lamp → Point.
 3. Older versions only: press F5 to enter the shading menu
 4. Change the color to reddish-orange. (Red: 1, Green: 0.1, Blue: 0)
 5. Set the Energy to around 7.
 6. Raise the light until it's just above the bottom of the crater ( G rab along the Z axis).
 7. If the ground level of your plane is reflecting light from the lava lamp this is because the bottom of your crater is above ground level of the plane you created; you'll need to turn on ray-tracing. in the object data menu for the light, open the Shadow menu and click "Ray Shadow"
 - Alternate 1: Spot Lamp
 1. Change the light's type to Spot.
 2. Raise the light until it's covering most of the crater. If the light is not pointing down, R otate and angle it downwards.
 - Alternate 2: Area Lamp
 1. Change the light's type to Area.
 2. R otate along the Y axis: 180 degrees.
 3. Set Gamma to 2.
 4. Set Distance to around 5.
Experiment with the values and positioning to get something that works with your volcano.
It should now look like this:
Blender volcano magma.jpg
Varying the Terrain[edit]
Next, let's set the volcano's material.
 1. RMB on the volcano plane.
 2. Select the "Material" button Materials button.png and press New.
 3. Change the color to ashen gray. (Red:.260, Green: 0.230, Blue: 0.230)
 4. Select the "Texture" button and press New.
 5. Change the Type to Stucci.
 6. In the Influence panel, uncheck Color, and check Normal. Set the Normal slider to 0.5. This will render the texture as a bump-map.
Older versions:
Select the volcano and press F5. Keep Pressing F5 until the Materials Buttons (


text:
The Reverse-Robin-Hood-Cross-Subsidy Hypothesis: Do Credit Card Systems Effectively Tax the Poor and Reward the Rich?
Robin Hood and his band of merry men infamously, if apocryphally, robbed from the rich and gave to the poor. Over the last decade, some economists have postulated that credit card companies do the opposite – forcing low-income cash customers to pay higher prices for retail goods that effectively fund the frequent flier miles and other rewards that go predominantly to affluent cardholders. Because the credit card systems prohibit surcharging, everyone pays the same price. But, these analysts reason, merchants inflate their prices across the board to cover the cost of credit card acceptance. While credit card customers are rewarded handsomely, the poor, who often use cash or checks, get the shaft. In this sense, these commentators claim, card systems are reversing Robin Hood's redistributive quest.
Until recently, the reverse-Robin-Hood-cross subsidy ("RRHCS") hypothesis was limited largely to theoretical economic analysis. Not any longer. Merchants have recently filed more than 50, now consolidated, cases against the card systems' alleging that "the No-Surcharge Rule effectively compels cash payers and users of other low-cost payment forms to subsidize all of the costly perquisites given by [Card-]Issuing Banks to consumers using more expensive payment forms such as Visa and MasterCard Payment Cards, including frequent-flier miles, rental-car insurance, free gifts, and even cash-back rewards." The potential damages in these cases are said to exceed the annual pre-tax profit of the entire U.S. banking industry.
This Article questions the RRHCS hypothesis, providing reasons to doubt that card use increases retail prices in a substantial and systematic way. Although the best available evidence indicates that merchants pay more out-of-pocket to accept credit cards than they do for other forms of payment, these costs are only half the story. Credit cards provide significant benefits to merchants that could outweigh the incrementally higher out-of-pocket costs and thus lead to lower retail prices. Although the evidence is inconclusive, credit card acceptance appears to make all consumers better off than they would be if the particular merchants with whom they deal did not accept cards.
Second, this Article demonstrates that the empirical evidence allegedly proving the hypothesis – surveys of gasoline retailers in the 1980s – in fact does not. Factors unique to gasoline retailing are more likely to explain the cross subsidies that existed in the 1980s than any generalizable principal about the relationship between card acceptance fees and retail prices. Moreover, when viewed in the context of the entire card-accepting economy, the 1980s gas station experience may cut against the RRHCS hypothesis. The data show that when a significant cross subsidy favoring card users existed, a significant percentage of the dealers in a large and profitable industry adopted a cash-discounting policy. The paucity of similar discounting schemes today – or alternatively merchants that do not accept credit cards – suggests that the 1980s gas station experience was unique and that substantial cross-subsidies across means of payment are now rare.
Lastly, this article evaluates the impact of any potential subsidy favoring credit card use within an economy that is rife with similar ones. It proposes measures aimed at bringing those who have no banking relationships into the system. Enabling more consumers to benefit from banking services, including credit cards, would provide a greater public service than battling a cross subsidy that may not exist.
Steven Semeraro. 2008. "The Reverse-Robin-Hood-Cross-Subsidy Hypothesis: Do Credit Card Systems Effectively Tax the Poor and Reward the Rich?" ExpressO
Available at: _URL_


text:
The predecessor to roulette was multi-person Mazing, a normal maze except with several people participating. Roulette is this concept inverted, however, inverted mazes existed before roulette. The term and rules were popularized and created by players TiTnAsS and Kesshutsu.
- Requires at least two players, but more is better.
- In the beginning of the round, follow the left cycle wall on the outside. Everyone should be going clockwise.
- Leave enough room to go back in between the walls that you and the person you are following create
- Keep following the walls around the arena until you get close to the outer rim.
- Double back to your right and enter the tunnel you have created, and follow it to the middle.
- Once you get back in the middle of the giant mass of tunnels, turn left and go out the closest tunnel created by another player.
This first image is a screenshot of the players making the mass of tunnels. As you can see, they are all moving clockwise around the outer side of the walls, and leaving enough space to turn back inbetween the tunnels when they need to.
This screenshot is the players doing the same thing as the above screenshot, just so you can get a different perspective on it.
This next screenshot, is the players sequentially turning back into their tunnels. This picture is to illustrate the point of Rouletting.
This screenshot, is to show you what the inside of the roulette is like, and how you should go about navigating it.
This last screenshot is to illustrate that the players following the wall in front of them can pull off and create new swerves. These swerves serve as extra turns that create a harder and more fun tunnel for each player.
Good Servers for Roulette
- Breakfast in Shrunkland
- World of TNA (has a map built for Roulette)
Differences Between Mazing
Roulette and multi-person mazes are related but differ significantly
- Mazing is an abstract skill, roulette is game with set rules.
- In roulette each player creates their own path to maze back into. In a multi-person maze everyone uses the same path.
- You can not roulette by yourself.


Print 101 comment(s) - last by FaceMaster.. on Feb 9 at 3:41 PM
Scientists have cloned a Pyrenean ibex, an extinct genetically distinct subspecies of the Spanish ibex, shown here. The ibex, known for its curved horns went extinct in 2000. Scientists resurrected it with a skin sample, though it was born with a lung defect and soon died. (Source: Jose Luis GOMEZ de FRANCISCO/
New cloning work could clear the way for resurrection of many recently extinct beasts
In the realm of commercial cloning, trickled-down technology from this cutting edge field of research has allowed firms to offer pet cloning services. And in the realm of research, tremendous advances continue as scientists are hatching plans to resurrect extinct beasts. Scientists have almost finished mapping the Woolly Mammoth genome, and have already injected DNA from an extinct species into a mouse.
Now arguably the greatest landmark event for the field of cloning has occurred. Scientists have for the first time cloned an extinct animal, the Pyrenean ibex, a form of wild mountain goat. The really spectacular thing about this cloning effort is that it was done using only DNA from skin samples.
Technically classed as a genetically distinct subspecies of the Spanish ibex, the Pyrenean ibex, or bucardo as it is called by the locals, used to roam the mountainous hillside of northern Spain. Known for its distinct horns, the animal was a popular target for hunters, and by the 19th century only 100 were left. The species was not declared protected until 1973, at which time there were around 30 animals. In 2000, the last known member of this critically endangered species was found dead on a hillside. Researchers at the time decided to wisely preserve skin samples in liquid nitrogen.
The well-preserved skin samples proved a fruitful source for DNA. Replicating this DNA using common genomic techniques, the researchers injected it into goat eggs, replacing the goat DNA.
While a great success, the effort also showcased the difficult road ahead for producing viable clones. While born alive, the newborn ibex kid had defects in its lungs, similar to those found in many cloned sheep, and they proved fatal. However, as some sheep clones have lived relatively normal lifespans, the success raises the hope of a more permanent resurrection.
Dr Jose Folch, from the Centre of Food Technology and Research of Aragon helped lead the research. He states, "The delivered kid was genetically identical to the bucardo. In species such as bucardo, cloning is the only possibility to avoid its complete disappearance."
Professor Robert Miller, director the Medical Research Council's Reproductive Sciences Unit at Edinburgh University who heads a northern white rhino cloning effort funded by the Royal Zoological Society of Scotland cheered the news. He states, "I think this is an exciting advance as it does show the potential of being able to regenerate extinct species. Clearly there is some way to go before it can be used effectively, but the advances in this field are such that we will see more and more solutions to the problems faced."
The race is now on to make sure that critically endangered species' tissues are preserved for future cloning efforts. Britain's Zoological Society of London and America's Natural History Museum have teamed up in a project called Frozen Ark. They are in the process of storing samples from thousands of species.
While cloning a dinosaur is highly improbable due to DNA's chemical tendency to rapidly break apart to the point where it cannot be sequenced, this new breakthrough paves the way for cloning of both endangered species, and extinct species with fully sequenced genomes, such as Neanderthals or, likely soon, the Woolly Mammoth. However, this new work also highlights the extreme challenge ahead in trying to establish a sustainable population of a cloned animal, or even clones that live to reach adulthood.
Comments Threshold
By otispunkmeyer on 2/2/2009 9:49:22 AM, Rating: 4
its like environmentalists trying to save some dying out species today. theres usually a good reason its dying just wasnt meant to be. (though i do agree somewhat with those trying to stop poaching of animals)
i read an example about some australian swamp toad and animalists wanting to save it. truth is this thing was just super inane, wasnt particularly clever and seemed to have little compulsion to mate. basically, mother nature had doomed it to extinction...natural selection, survival of the fittest and all that. its natural end was to stop existing.
but in trying to save it, they spent a lot money basically working against nature. stupid. what a waste.
i swear some environmentalists take things so far that they are actually altering/damaging the thing theyre trying to save in the process.
By masher2 (blog) on 2/2/2009 10:30:19 AM, Rating: 5
Also left out is the fact that this particular creature is just a subspecies of Spanish ibex in general. In recent years, environmentalist-minded biologists have been playing the "species game" where they define trivial variations in a population as entirely separate species, so they can justify their protection under the Endangered Species Act.
There are a few hundred different breeds of dogs. All can fertilely interbreed, just as all the various Ibex species can (actually Ibex can also interbreed with goats and turs as well). Should every breed of dog be considered a separate species, entitled to legal protection?
By masher2 (blog) on 2/2/2009 1:29:50 PM, Rating: 5
a lot of dog breeds, if not most of them, are so inbred that they do not make a separate species
Why not? Genetically, a poodle varies much more from a Labrador than a Pyrenean Ibex does from a Spanish Ibex.
The old test of viability of offspring may not have been a perfect standard, but at least it was a standard. Now, we have nothing. No rules.
How much variation should be required to define a new species? Every plant and animal is genetically distinct. With these new policies taken to their logical conclusion, every time an animal dies, one can say a "species" has gone extinct.
One of the most blatant cases of species gerrymandering was the famous spotted owls debacle. In this case, even the fiction of genetic variation wasn't used. The "species" was defined by which side of a highway the owls were found on. Live on this side, and you're a California Spotted Owl, thriving and in no need of protection. Fly across the highway, and the bird instantly becomes a "Northern" Spotted Owl, in need of special protection-- protection which resulted in massive restrictions to the lumber industry.
By ayat101 on 2/2/2009 10:40:02 PM, Rating: 2
Nonsense... read up the test for new species: viability and stability, plus some breeding isolation. Inbreeding with other species is not a counterargument. That was your argument and it was wrong. Simple.
Don't know how you worked out that these two goats are less related than poodle et al... care to provide a reference?
It's a bit pointless discussing science with you, because repeatedly you make obvious mistakes (i.e. you do not know the basic accepted principles of the area you are talking about... and then when these accepted principles disagree with your OPINION you blame enviromentalists or greenpeace).
PLUS... your peanut gallery and cult of Masher on these boards downrates the posts that disagree with you. It is ridiculous that when I post the accepted scientific view I get downrated... and you get uprated for opposing science. It is downright cultist behaviour.
By masher2 (blog) on 2/2/2009 11:26:06 PM, Rating: 2
read up the test for new species: viability and stability...
This "species" was obviously neither viable nor stable. So much for that argument.
plus some breeding isolation
Any purebred breed of dog has more breeding isolation than most of the multitudinous subspecies of mountain goats.
When it takes a trained biologist and a physical exam to tell the difference between two "species", there isn't much of a difference. In fact, the only functional difference between all four of the subspecies of Capra pyrenaica is which part of the Iberian Peninsula they lived in.
It's a bit pointless discussing science with you
But you're not discussing science. You're simply tossing insults.
If you want to debate, why not try an actual fact, logical counterargument, or reasonable facsimile thereof? For starters, why not dispute my assertion that there is no reasonable criteria for differentiating between the 'Northern' Spotted Owl and the 'California' Spotted Owl? They're essentially the same bird, defined only by which side of a road they happen to be on at the time.
By lucasb on 2/3/2009 2:04:01 PM, Rating: 2
It's a bit pointless discussing science with you
Couldn't agree more. Arguing about science with Masher is useless. He's full of free market rhetoric and other (deeply) flawed ideological biases. There are only three choices: he knows next to nothing about real science, he suffers some sort of delusional disorder or he's a shill for some interest group.
You can clearly see this


Take the 2-minute tour ×
I am working on the statement " A graph $G$ is a $nKn$ (collection of $n$ number of complete graph each of order $n$) graph if and only if $\bar{G}$ is $α(G) = α(\bar{G}) = n$ and $(p-n)$-regular, where $p$ is the order of $G$ and $α(G)$ is the independence number of $G$ with $n\geqslant 1$."
The converse part seem to be a confusion. Kindly help me with it.
share|improve this question
Perhaps you could edit the meaning of $a(G)$ into your question. – Gerry Myerson May 9 '12 at 12:58
α(G) is the independence number of G – James Alex May 9 '12 at 14:07
I'm not sure I'm understanding the question properly. Can you clarify why the graph $G$ consisting of a 3-cycle and a 4-cycle would not be a counterexample? It would seem to satisfy $n=3$, $p=7$, but it is obviously not a $3K_3$. – Will Orrick May 10 '12 at 16:48
_USER_ The graph you mentioned is 2 regular, not (7-3)=4 regular. – Graphth May 10 '12 at 20:20
_USER_ : Hmmm. I had understood that it was $\overline{G}$ that was required to be $(p-n)$-regular, rather than $G$. Perhaps this is the root of my confusion. I'm now not sure that I understand how $3K_3$ is defined. Wouldn't $p$ equal 9 in that case, and $G$ have to be 6-regular? – Will Orrick May 10 '12 at 21:41
1 Answer 1
(Extended compilation of comments.)
While it is true that the disjoint union of $n$ copies of $K_n$ has the properties
 1. $\alpha(G)=\alpha(\overline G)=n$ (where $\alpha$ is the independence number)
 2. $\overline{G}$ is $p-n$ regular (where $p$ is the number of vertices of $G$)
the converse is not true. not every graph with properties 1 and 2. Will Orrick gave the following counterexample in comments: let $G$ be the disjoint union of two cycles $C_3 $ and $C_4$; then $\alpha(G)=\alpha(\overline G)=3$ and $\overline{G}$ is $4$-regular where $4=7-3$.
Brian M. Scott then observed that if $\alpha(\overline G)=n$ is strengthened to
(*) every maximal independent set in $\overline G$ has cardinality $n$
then the conclusion $G=nK_n$ follows. Indeed, (*) says that every maximal clique of $G$ has cardinality $n$. Therefore, every vertex is contained in a copy of $K_n$. Since $G$ is $n$-regular (by virtue of 2), it is a disjoint union of some copies of $K_n$. The condition $\alpha(G)=n$ places the number of the copies of $K_n$ at $n$.
share|improve this answer
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text:
Pronunciation: (hip'u-krit),[key] —n. 1. a person who pretends to have virtues, moral or religious beliefs, principles, etc., that he or she does not actually possess, esp. a person whose actions belie stated beliefs.
2. a person who feigns some desirable or publicly approved attitude, esp. one whose private life, opinions, or statements belie his or her public statements.


modulus of volume expansion
Shearing Deformation
Shearing Deformation
Shearing forces cause shearing deformation. An element subject to shear does not change in length but undergoes a change in shape.
The change in angle at the corner of an original rectangular element is called the shear strain and is expressed as
$\gamma = \dfrac{\delta_s}{L}$
The ratio of the shear stress τ and the shear strain γ is called the modulus of elasticity in shear or modulus of rigidity and is denoted as G, in MPa.
$G = \dfrac{\tau}{\gamma}$
The relationship between the shearing deformation and the applied shearing force is
$\delta_s = \dfrac{VL}{A_s G} = \dfrac{\tau L}{G}$
where V is the shearing force acting over an area As.
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Dutch auction
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A 1957 Dutch auction in Germany to sell fruits
A Dutch auction is a type of auction in which the auctioneer begins with a high asking price which is lowered until some participant is willing to accept the auctioneer's price, or a predetermined reserve price (the seller's minimum acceptable price) is reached. The winning participant pays the last announced price. This is also known as a clock auction or an open-outcry descending-price auction.
This type of auction is convenient when it is important to auction goods quickly, since a sale never requires more than one bid. Theoretically, the bidding strategy and results of this auction are equivalent to those in a sealed first-price auction.
Auction process[edit]
In a Dutch auction, the item being sold is initially offered at a very high price, well in excess of the amount the seller expects to receive. Bids are not sealed, as they are in some types of auctions. The price is lowered in decrements until a bidder accepts the current price. That bidder wins the auction and pays that price for the item. For example, suppose a business is auctioning off a used company car. The bidding may start at $15,000. The bidders will wait as the price is successively reduced to $14,000, $13,000, $12,000, $11,000 and $10,000. When the price reaches $10,000, Bidder A decides to accept that price and, because he is the first bidder to do so, wins the auction and has to pay $10,000 for the car.
Dutch auctions are a competitive alternative to a traditional auction, in which bids of increasing value are made until a final selling price is reached, because due to ever-decreasing bids buyers must act decisively to name their price or risk losing to a lower offer. [1]
A second price auction[edit]
There is some confusion over terminology. Some financial commentators and some third-party auction sites use the term Dutch auction to refer to second-price auctions, which are different from Dutch auctions.
In a second price auction, the seller offers more than one identical item for sale, so that there may be more than one winning bidder. Each bidder can bid for all the items or only some of them, and publicly indicates the price that he/she is willing to pay for each item. However, all winning bidders need to pay only the lowest qualifying (successful) bid. If there are more successful bids than items available, priority goes to the bidders who submitted their bids first.
In order to beat a competing bidder, one must bid a higher price per item than that competitor, regardless of the number of items that are being bid for. Here is an example of how this might work:
The seller auctions 5 identical items.
 1. Bidder "High" bids for 4 items at $21 each.
 2. Bidder "Mid" bids for 2 items at $20 each.
 3. Bidder "Low" bids for 3 items at $18 each.
The outcome of this auction would be:
 1. Bidder "High" wins all the items they sought (qty 4), at $20 each.
 2. Bidder "Mid" wins 1 of the 2 items they sought (because no more remain), also at $20 each.
The price is $20 because that was the lowest successful bid (hence the second price). Since Bidder "Mid" was only awarded 1 item, and his original bid was for 2 items, he has the right to refuse the purchase of that partial amount. As a winning bidder, you have the right to refuse paying only if you are awarded less than the number of the items you were bidding on. If this were a Dutch Auction, the first bid made wins the item, regardless of value.
Public offerings[edit]
The United States Department of the Treasury, through the Federal Reserve Bank of New York (FRBNY), raises funds for the U.S. Government using a Dutch auction.[citation needed] The FRBNY interacts with primary dealers, including large banks and broker-dealers who submit bids on behalf of themselves and their clients using the Trading Room Automated Processing System (TRAPS), and are generally told of winning bids within fifteen minutes.
For example, suppose the sponsor of the issuance is seeking to raise $10 billion in ten-year notes with a 5.125% coupon and in aggregate the bids are as follows:
 - $1.00 billion at 5.115% (highest bid)
 - $2.50 billion at 5.120%
 - $3.50 billion at 5.125%
 - $4.50 billion at 5.130%
 - $3.75 billion at 5.135%
 - $2.75 billion at 5.140%
 - $1.50 billion at 5.145% (lowest bid)
In this example the % at high is 66.66%, meaning only $3 billion of the $4.5 billion at 5.130% will get bonds. Bids will be filled from the lowest yield (highest price) until the entire $10 billion has been raised. This auction will clear at a yield of 5.130%, and all bidders will pay the same amount. In theory, this feature of the Dutch auction format leads to more aggressive bidding as those who in this case bid 5.115% will receive the bonds at the higher yield (lower price) of 5.130%.
A variation on the Dutch auction, OpenIPO, was developed by WR Hambrecht and has been used for 19 IPOs in the US. Auctions have been used for hundreds of IPOs in more than two dozen countries, but have not been popular with issuers and thus were replaced by other methods. One of the largest uniform price or "Dutch" auction IPOs was for Singapore Telecom in 1994. The 1994 auction IPO of Japan Tobacco was substantially larger (with proceeds more than double those of Singapore Telecom and triple those of Google), but this auction was discriminatory or pay-what-you-bid, not uniform price or "Dutch". SRECTrade.com uses a two-sided Dutch auction to trade Solar Renewable Energy Credits (SRECs).
Dutch auction share repurchases[edit]
The introduction of the Dutch auction share repurchase in 1981 allows firms an alternative to the fixed price tender offer when executing a tender offer share repurchase. The first firm to utilize the Dutch auction was Todd Shipyards. A Dutch auction offer specifies a price range within which the shares will ultimately be purchased. Shareholders are invited to tender their stock, if they desire, at any price within the stated range. The firm then compiles these responses, creating a supply curve for the stock.[2] The purchase price is the lowest price that allows the firm to buy the number of shares sought in the offer, and the firm pays that price to all investors who tendered at or below that price. If the number of shares tendered exceeds the number sought, then the company purchases less than all shares tendered at or below the purchase price on a pro rata basis to all who tendered at or below the purchase price. If too few shares are tendered, then the firm either cancels the offer (provided it had been made conditional on a minimum acceptance), or it buys back all tendered shares at the maximum price.
See also[edit]
 1. ^ _URL_
 2. ^ To understand the Dutch auction bidding and outcome from actual shareholder tendering responses, see Bagwell, Laurie Simon, "Dutch Auction Repurchases: An Analysis of Shareholder Heterogeneity,". 1992. Journal of Finance, Vol. 47, No. 1, 71–105.


text:
The need for collaboration skills in today's market is increasing, with more businesses looking for ways to streamline communication, improve innovation, and share corporate knowledge. Students at the beginning of their college careers have had numerous opportunities to work in groups, but very few opportunities to engage in true collaboration. This Teaching Tip provides an approach to teaching collaboration as part of an Introduction to Computer Information Systems course, and incorporating it into course work so students can begin to develop the skills they will need for workplace collaboration. Initially, students tend to see collaboration and cooperation as interchangeable terms; the approach outlined here focuses on the collaboration concepts of content sharing, feedback, and iteration. By applying these concepts and using a collaboration tool like Microsoft SharePoint, the instructor can guide the students to understanding true collaboration.
Atkins, Laura and Cole, Carey
"An Introduction to Collaboration with SharePoint for First-Year Business Students,"
Journal of Information Systems Education: Vol. 21
, Article 2.
Available at: _URL_


each-one-teach-oneThree positions that you need for Destiny.
The amazing thing is that many of you are already in the three positions whether you know it or not.
The first position you need as you are headed to your destiny is someone that you are teaching
Now granted, the way these three positions are listed in this post are not necessarily the order in which you should look to walk in or obtain them. However, they are all needed and would be great to have all of these positions working properly in your life at the same time to yield greater measures of success. This should be your intentional goal!
Why do you need someone you are teaching?
One of the reasons you need someone you are teaching is because there is always someone in the world who needs a measure of guidance. I'm sure you can remember a time where you just need someone's advice who had already gone in the direction you are going. There are many people waiting for that same type of information for their break through to their next level. If you have already accomplished something or gone a certain measure of steps you likely have valuable information to share with someone else, whether it's what to do or what not to do!
Did you know someone may already consider you their teacher, even if they haven't told you? People make people their mentor's from a far without even making them aware! They may not have tapped you on the shoulder and made you aware. They may not have said, "Hey, I'm following you" Remember I said some of the positions you may be operating in and may not be aware.
People who need understanding often look at people who have titles such as a Realtor, photographer, Licensed Cosmetologist, husband, wife, mother, father, or someone with a Ph. D because they desire that position.
We need to be in a position where we want to do better, not just because we are teaching someone else, but because we know we deserve better and as we develop personally we bring increase into our lives!
Side Bar:
How many of you know that just because a person holds a title does not mean they will fulfill the position properly.
Therefore there are advantages to being aware of when you are actually operating in these positions for greater. Being aware makes you more sensitive to how you do life and how you do business. Awareness gives you an even greater desire to do business on an even greater. Not only does it help the person who is watching you but it also helps you in developing in your measure of success and greatness as well.
The Second Position needed for Destiny is a Peer Group
A peer group is a group of people approximately the same age, headed in the same direction, with similar goals, and daily life activities.
Here are some advantages of a Peer Group.
~A Peer Group gives you insight for overcoming obstacles
~You can gain collective information about contacts or resources from those in your peer group
~Also, accessible support from those in a peer group is available. You will need good support and accountability to maintain the motivation and momentum need to complete your goals and desires.
Actually, trying to do it alone can slow up or hinder the momentum for your destiny!
Many of you have a peer group but may not be aware of it!. They are the 5 People you spend the most time with!
Theses 5 people will affect your belief, your income, your decisions and ultimately your destiny.
Like individuals headed in the same direction will have similar experiences when shared will let you know some of the things you are facing are normal!
The Third Position Needed for Destiny is Someone to teach you!
Let's face it, where you are now is based on the information you had up until this point. Next level will require new next level information!
Whether you choose a Life Coach, Mentor, or Business Consultant they should have few qualities.
~They should have information and experience about your "next" level, the areas you are stuck in, and strategies to get there.
They should have similar values as you do
 because they will share information through their experience that will likely head you in similar directions.
If you find that you have all of these positions in place but you are still stuck in your business, I invite you to join my next virtual online class on October 19 right from your home called "LEVEL UP". It a class on Clarity to provide things business owners need in today's time to be relevant and prosper. You will be able to have a level up conversation to see if you have things in place that are going to help get you unstuck and onto your next level!.
tanyadsc2_8636From My Experience to Yours
Business Consultant/ Certified Life Coach
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Between 1917 and 1930, homosexuality was decriminalised in the Soviet Union. From the Wikipedia article on LGBT history in Russia:
The Russian Communist Inessa Armand publicly endorsed both feminism and free love, but never directly dealt with LGBT rights.[6] The Russian Communist Party effectively legalized no-fault divorce, abortion and homosexuality, when they abolished all the old Tsarist laws and the initial Soviet criminal code kept these liberal-libertarian sexual polices in place.[7] During this time, openly gay persons were able to serve in Russia's new Soviet government.
Yet, the legalisation of private, adult and consensual homosexual relations only applied to Russia itself. Homosexuality or sodomy remained a crime in Azerbaijan (officially criminalised in 1923), as well as in the Transcaucasian and Central Asian Soviet Republics throughout the 1920s.[8] Similar criminal laws were enacted in Uzbekistan in 1926 and in Turkmenistan the following year.[9] Criminalisation of homosexuality during this time was exclusive to nations of the Soviet Union associated with "cultural backwardness."
The Wikipedia article really only considers the legal situation, apart from the unsourced statement openly gay persons were able to serve in Russia's new Soviet government.
What was the situation for gays in this time period in practice, specifically in the RSFSR? Did the fact that homosexuality was legalised as one of the first countries in Europe mean that it was a preferable place for practicing gays to be compared to countries in Western Europe. In Western Europe many countries didn't legalise homosexuality until decades later? Or was this just a law that looked nice on paper, but had no meaning in practice?
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Are you sure that this was the work of the Bolshevik and not of the Provisional Government? – Felix Goldberg Feb 26 '13 at 0:05
_USER_ Goldberg how the Provisional Government could create the RSFSR criminal code? – Anixx Feb 26 '13 at 1:19
One big problem with this question is that "gay" culture and identity is a Western post-1968 phenomena—any answer will have to respond within a theoretical framework of the nature of human sexuality. Another problem is that the very real distinction between formal and substantive freedom requires an answer that uses a theorisation of human freedom. Within these limits, that any answer will be embedded in a particular discourse of what sexuality and liberation are, the question is answerable. – Samuel Russell Feb 26 '13 at 3:02
_USER_ you are completely wrong. There were no forced medical treatment of homosexualism before it was criminalised not to say, inmates of mental hospitals newer were used for any kind of serious labor. – Anixx Feb 26 '13 at 14:30
I'm suggesting that your terms are anachronisms meaning that your question is unanswerable as there was no "gay" situation in 1917. – Samuel Russell Feb 28 '13 at 2:02
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This looks like a great area for more research. The question makes the important distinction between what is found (or in this case, not found) in law, and what actually happens in practice. This is especially the case when we are talking about Soviet law. Below I'll summarize what little I could determine from these three sources:
 1. Sex and Russian Society edited by Igor Kon and James Riordan
 2. Sexual Revolution in Bolshevik Russia by Gregory Carleton
 3. Homosexual Desire in Revolutionary Russia by Dan Healey
In (1) this is discussed primarily on p90-91. The overall emphasis seems to be that during this early period, was that the Bolsheviks did not put much active emphasis on the issue. It notes that Anarchists and Cadets "officially proposed" revoking legislation against homosexuals while the Bolsheviks took no position. However, its absence from the Russian Criminal Code in 1922 and 1926 effectively decriminalized it, as you pointed out.
In terms of practice (1) merely mentions that a group of homosexuals that referred to themselves as the "blues" included (according to one source) prominent figures such as Foreign Affairs Commissar Georgi Chicherin (also mentioned in the short article in _USER_'s answer and probably the source of the official in government you quoted), poets like Mikhail Kuzmin, Nikolai Klyuev, Sofie Parnak, and director Sergei Eisenstein. While not illegal, towards the key early 1930s turning point it was increasingly pathologized, rather than seen as a crime.
In (2), Carleton points to the surprising defense of freedom in sexuality in a 1927 work called Sexual Crimes arguing that it did not violate anyone's rights (p60). Later, however, it emphasizes the diversity of opinions in the writings of early Soviets with some seeing as "outside the proletarian norm" (p78) or "were no longer authentic members of the proletariat" (p142) while others, such as Israel Gelman, who studied the sexual behavior of postrevolutionary youth, called it as a "sickness" and "perverse" but not to be condemned or persecuted.
(3) by Healey, is perhaps the most cited book discussing this issue during the period you are interested it. As also true with (1) I had limited access to it through Google Books. Chapter 4 and 5 are of interest to your question. Healy argues as others have, that "the silence in the penal code...offered new opportunities for medicine in an area formerly dominated by police approaches" (p148) There is a lot more here but I am not able to get access to it. A review of the book in The Journal of Sex Research Vol. 39, No. 3, Aug., 2002 by Stephen O. Murray (limited access:, p247 which argues that Healey goes beyond what his sources can show him. He questions Healey's effort to locate "clear intention" to remove sodomy from the criminal code or an "explicit decision". Murray points out that _PHONE_ there was "no single official position on homosexuality" in the "Slavic heartlands" but "treated with suspicion as being 'unproletarian'...decadent bourgeois behavior," and he also quotes German sex-reformer Magnus Hirschfeld visiting in 1926 as not seeing "any open organized group of homosexuals in the new Russia and that Soviet journalism and literature were silent about the question" - which he contrasts with liberal late Czarist Russia.
These three works give some hints, but I didn't find much mention about the lived experiences and practical impact of the [lack of] policy on homosexuals on the ground. Some of this may be covered in Healey sections I was not able to view. Beyond laws, of course, the discriminations faced on a daily level or the need felt by individuals to conceal their sexuality is another matter that may be difficult to find through available primary sources. There may be extensive literature in Russian on this, and hopefully someone can contribute with more on this.
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Here is a radio program (and transcript) that covers the topic amongst a wider examination:… – EndlessLoop Feb 25 '14 at 21:55
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Given that $z^2 + z + 1 = 0$ where $z$ is a complex number, how do I proceed in calculating $z^4 + \dfrac1{z^4}$?
Calculating the complex roots and then the result could be an answer I suppose, but it's not quite elegant. What alternatives are there?
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7 Answers 7
up vote 31 down vote accepted
From $z^2 + z + 1 = 0$, we have $$z +\frac{1}{z}=-1.$$ Taking square, we get $$z^2 +\frac{1}{z^2}+2=1,$$ which implies that $$z^2 +\frac{1}{z^2}=-1.$$ I think you will know what to do next.
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I see... Thank you for the quick answer! – Mihai Bişog Jan 1 '12 at 11:54
$\displaystyle{z^{2^k}+\frac{1}{z^{2^k}}=-1}$ for all $k$. – Jonas Meyer Jan 1 '12 at 11:54
_USER_: nice observation! – Paul Jan 1 '12 at 12:06
Dickson polynomials FTW! – Jyrki Lahtonen Jan 1 '12 at 14:20
Another way to justify that $z+\dfrac1{z}=-1$ is that due to the coefficient symmetry, if $z$ is a root, then $\dfrac1{z}$ is a root as well. By Vieta, then, the sum of those two roots ought to be the negative of the coefficient of the linear term... – Ｊ. Ｍ. Jan 1 '12 at 15:15
Essentially the same calculation also follows from the observation that $x^2+x+1=\phi_3(x)$ is the third cyclotomic polynomial. So $z^3-1=(z-1)(z^2+z+1)=0$, and hence $z^3=1$ for any solution $z$. Therefore $$ z^4+\frac{1}{z^4}=z\cdot z^3+\frac{(z^3)^2}{z^4}=z+z^2=-1. $$
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Very clever! :D – Ｊ. Ｍ. Jan 1 '12 at 12:08
Very nice! If you had not posted this already, I would have used the sum of geometric series (instead of cyclotomic polynomials) to write $$0=z^2+z+1=\frac{z^3-1}{z-1}\Rightarrow z^3=1$$ and $$z^4+\frac{1}{z^4}=(z^3)z+\frac{1}{(z^3)z}=z+\frac{1}{z}=\frac{z^2+1}{z}=\frac{-z}{z}=-1.$$ – Dilip Sarwate Jan 1 '12 at 15:48
$$\begin{align*} z^4+\frac1{z^4}&=(-z-1)^2+\frac1{(-z-1)^2}\\ &=z^2+2z+1+\frac1{z^2+2z+1}\\ &=(-z-1)+2z+1+\frac1{(-z-1)+2z+1}\\ &=z+\frac1{z}=\frac{z^2+1}{z}=\frac{-z-1+1}{z}=-1 \end{align*}$$
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What would be wrong with systematic reduction using the minimal polynomial? Nothing! – Jyrki Lahtonen Jan 1 '12 at 12:25
Here is an alternative approach: let's consider $z^{8}+1$, and then divide by $z^{4}$.
By using geometric series, notice that $$z^{8}+z^{7}+z^{6}+z^{5}+z^{4}+z^{3}+z^{2}+z+1=\left(z^{2}+z+1\right)\left(z^{6}+z^{3}+1\right)=0.$$ Now, as $z^{2}+z+1=0$, we know that both $z^{7}+z^{6}+z^{5}=0$ and $z^{3}+z^{2}+z=0$, and hence $$z^{8}+z^{4}+1=0$$ so that $z^{8}+1=-z^{4}$. Thus, we conclude that $$z^{4}+\frac{1}{z^{4}}=-1.$$
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Different people see different things in the relation $z^2+z+1=0$. Just as Jyrki did, I see the third cyclotomic polynomial. Its roots are $-1/2 \pm \sqrt{-3}/2$, the two primitive cube roots of unity. Call one of these $\omega$ and see that $\omega^3=1$, so that $\omega^4=\omega$ and $\omega^{-4}=\omega^2$. Their sum is $-1$, from the defining relation.
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Hint $\ $ Exploit innate symmetry: for $\rm\ y = z^{-1} $ you know $\rm\ yz\ (=\: 1)\:$ and $\rm\ y+z\ (=\: z^{-1}\!+z\: =\: -1)\ $
Thus you know $\rm\ \ \ y^2 + z^2\ =\ (y\ +\ z)^2-\ 2\:(y\:z)$
hence you know $\rm\ y^4 + z^4\ =\ (y^2\! + z^2)^2 - 2\:(y\:z)^2$
For more on symmetric polynomials see the Wikipedia article on Newton's identities.
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To downvoter: if something is not clear then please feel welcome to ask questions and I will be happy to elaborate. – Bill Dubuque Jan 1 '12 at 22:52
$$z^2+z+1=0$$ Clearly $z \not= 0$ and therefore $$z+\frac{1}{z}=-1.$$ Note that $$z^{n+1}+\frac{1}{z^{n+1}}=(z+\frac{1}{z})(z^n+\frac{1}{z^n})-(z^{n-1}+\frac{1}{z^{n-1}}).$$ Therefore if we define the function $U:N \to N$ as $$U_n=z^n+\frac{1}{z^n}$$ then we have $U(0)=2$ and $U(1)=-1.$ Also $$U(n+1)=-U(n)-U(n-1)$$ for all $n \in N.$
Using this recurrence you can calculate $z^n+\frac{1}{z^n}$ for any $n \in N.$
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