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Biological "Clock" Influences Damage Done by Oxidative Stress

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 05 Aug 2008 00:13:51 +0000

For Immediate Release

Biological "Clock" Influences Damage Done by Oxidative Stress

Tuesday, August 5, 2008

Swing shift workers and frequent fliers beware -- scientists have identified yet another biological issue that relates to the "circadian clock" found in almost every species from insects to humans, and discovered that the time of day also affects the ability to resist oxidative stress.

In a new study just published by researchers from Oregon State University, it was found that fruit flies had their greatest ability to manage oxidative stress in the early morning, shortly before they had to deal with the challenges of the day -- and the least natural defense in late afternoon or evening, a time when DNA damage reached its peak.

When the gene that controls this process was completely removed by genetic manipulation, the fly's ability to deal with oxidative stress essentially disappeared.

Oxidative stress can occur during the normal metabolism of oxygen, when levels of "reactive oxygen species" become too high, normal defense mechanisms break down and cell damage results. This is an issue in several significant health concerns, ranging from heart disease to Alzheimer's disease, premature aging and cancer. It now appears that animals, through the genetics that control their circadian rhythms, have natural ebb and flow in handling oxidative stress based on time of day.

The studies examined the role of the gene "period" in fruit flies, which is already known to influence reproduction, sperm release, sleep cycles, drug sensitivities, learning ability, and other biological functions. Oxidative stress management can now be added to the list -- the study concluded that "the circadian clock gene 'period' is essential for maintaining a robust anti-oxidative defense."

This is the first report of this type of rhythmic susceptibility to oxidative stress, the study said. The research was led by Jaga Giebultowicz, an OSU associate professor of zoology.

"In fruit flies, the ability to deal with oxidative stress was very significant," said Natraj Krishnan, a research associate at OSU and co-author on the new publication, in Biochemical and Biophysical Research Communications.

"That doesn't automatically tell us what the effects would be in humans, but our ability to deal with oxidative stress is very important to our health," Krishnan said. "This could be a concern to people who routinely have disrupted sleep cycles, such as swing shift workers, people who work at night, travelers crossing time zones."

Almost all organisms on Earth have evolved with a reaction to the rhythmic changes in light from day to night, Krishnan said, and organize their activities in a time-related pattern called "circadian rhythm." But research in recent years is just beginning to understand how powerful these rhythms are, with physiological, biochemical and behavioral functions linked to them. The "clock" genes that control them have also been found to influence other critical life functions -- sleeping, feeding, reproduction, and now disease prevention. As a reflection of its evolutionary persistence and importance, the "period" gene is found in many animal species and expressed in almost every cell in the human body.

"There has been what some call a clockwork explosion of interest in this field," Krishnan said. "These genes seem to influence or control so many different metabolic functions, and disruption of those functions may have serious health implications."

Much of the research is being done with the fruit fly because its genome has been completely sequenced and many of its genes perform the same function as in higher animals, including humans.

The practical use of information in this area is still being developed, Krishnan said. The efficacy of some cancer treatment drugs has already been found to be largely dependent on the time of delivery. Mental acuity is not the same throughout the day, and it may be that individuals learn best at specific periods. And in humans it has been found that the risk of death from various pathologies varies with time of day.

These studies were supported by the National Institutes of Health.

Permalink: http://www.sflorg.com/comm_center/unv_science/p488_129.html

Time Stamp: 8/5/2008 at 12:01:05 AM UTC

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One In Ten Children Using Cough, Cold Medications

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Mon, 04 Aug 2008 18:02:03 +0000

For Immediate Release

One In Ten Children Using Cough, Cold Medications

Monday, August 4, 2008

Researchers from Boston Universitys Slone Epidemiology Center have found that approximately one in ten U.S. children uses one or more cough and cold medications during a given week. These findings appear in the August issue of the journal Pediatrics.

Pediatric cough and cold medications are widely marketed in the U.S. but surprisingly little is known about just how often they are used in children. This information is especially important in light of recent revelations that cough and cold medications are responsible for serious adverse events and even deaths among children.

To define the frequency and patterns of use, the researchers analyzed data between 1999 and 2006 from the Slone Survey, a national telephone survey of medication use in a representative sample of the U.S. population. The authors considered all oral medicines that are approved by the FDA to treat childrens coughs and colds.

The researchers found that in a given week, at least one cough and cold medication was used by 10.1 percent of U.S. children. In terms of active ingredients contained in these medications, exposure was highest to decongestants and antihistamines (6.3 percent each), followed by anti-cough ingredients (4.1 percent) and expectorants (1.5 percent).

Exposures to cough and cold medications was highest among 2-to 5-year olds and children under 2 years of age.

Among all the products used, 64.2 percent contained more than one active ingredient. The most commonly used product types were single-ingredient antihistamines, antihistamine/decongestant combinations and antihistamine/decongestant/anti-cough combinations. The researchers also found the use of cough and cold medications declined from 12.3 percent in 1999-2000 to 8.4 percent in 2005-2006.

According to the researchers the especially common use of cough and cold medications among young children is noteworthy. Given concerns about potential harmful effects and lack of evidence proving that these medications are effective in young children, the fact that one in ten U.S. children is using one of these medications is striking, said lead author Louis Vernacchio, MD, MSc, an assistant professor of epidemiology and pediatrics at Boston University School of Medicine.

Funding for this study was provided by the Slone Epidemiology Center at Boston University.

Permalink: http://www.sflorg.com/comm_center/unv_medical/p487_102.html

Time Stamp: 8/4/2008 at 5:52:43 PM UTC

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The Brightest, Sharpest, Fastest X-Ray Holograms Yet

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Fri, 01 Aug 2008 18:49:41 +0000

For Immediate Release

The Brightest, Sharpest, Fastest X-Ray Holograms Yet

Friday, August 1, 2008

The pinhole camera, a technique known since ancient times, has inspired a futuristic technology for lensless, three-dimensional imaging. Working at both the Advanced Light Source (ALS) at the U.S. Department of Energys Lawrence Berkeley National Laboratory, and at FLASH, the free-electron laser in Hamburg, Germany, an international group of scientists has produced two of the brightest, sharpest x-ray holograms of microscopic objects ever made, thousands of times more efficiently than previous x-ray-holographic methods.

The x-ray hologram made at ALS beamline 9.0.1 was of Leonardo da Vincis famous drawing, Vitruvian Man, a lithographic reproduction less than two micrometers (millionths of a meter, or microns) square, etched with an electron-beam nanowriter. The hologram required a five-second exposure and had a resolution of 50 nanometers (billionths of a meter).

The other hologram, made at FLASH, was of a single bacterium, Spiroplasma milliferum, made at 150-nanometer resolution and computer-refined to 75 nanometers, but requiring an exposure to the beam of just 15 femtoseconds (quadrillionths of a second).

The values for these two holograms are among the best ever reported for micron-sized objects. With already established technologies, resolutions obtained by these methods could be pushed to only a few nanometers, or, using computer refinement, even better.

The modern pinhole camera

Our purpose was to explore methods of making images of nanoscale objects on the time scale of atomic motions, a length and time regime that promises to become accessible with advances in free-electron lasers, says Stefano Marchesini of the ALS, who led the research. The technique we used is called massively parallel x-ray Fourier-transform holography, with coded apertures. What inspired me to try this approach was the pinhole camera.

The ancient Greeks made note of pinhole-camera effects without understanding them; later, pinhole cameras were used by Chinese, Arab, and European scholars. Renaissance painters learned the principals of perspective using the camera obscura, literally a dark room, with a pinhole in one wall that projected the outside scene onto the opposite wall.

The room had to be dark for the good reason that a sharp image requires a small pinhole, but a small pinhole also produces a dim image, says Marchesini. To get a brighter image without lenses you have to use many pinholes. The problem then becomes how to assemble the information, including depth information, from the overlapping shadow images. This is where coded apertures come in.

By knowing the precise layout of a pinhole array, including the different sizes of the different pinholes, a computer can recover a bright, high-resolution image numerically. Random pinhole arrays were first used in x-ray astronomy but soon evolved into regular rows and columns of tiny square apertures of varying dimension. These coded apertures are called uniformly redundant arrays, or URAs.

Marchesini knew that colleagues at Livermore were using URAs in gamma-ray detectors. He asked himself, What would happen if we put a URA right next to an object we were imaging with the x-ray beamline? It should allow us to create a holographic image one with orders of magnitude more intensity than a standard hologram.

Holography with x-rays

Holography was invented over 60 years ago by the physicist Dennis Gabor, but its use has long been limited by technology. Whereas a pinhole camera employs ray optics, in which the photons travel like a stream of particles, holography depends on the wave-like properties of light.

The principle is straightforward: a beam of light illuminates an object, which scatters the light onto a detector such as a photographic plate. Meanwhile a second, identical beam of light shines directly on the detector. The scattered light waves from the object beam form interference patterns with the unscattered light waves from the reference beam.

This interference pattern serves to reconstruct an image of the object. One easy way to do so, if the detector is a photo transparency, is for the observer to look through the transparency in the direction of the (now absent) object; if only the reference beam is shining on the detector, the interference pattern serves to unscatter (diffract) the wavefront and reconstruct the objects image.

Lasers, which produce coherent light (all the same phase) were the first invention that made holography practical; it is now possible to make small holograms using just a laser pointer. FLASH is a powerful free-electron laser (FEL); a new generation of FELs of much shorter wavelength will be capable of producing coherent light pulses so short theyll be able to freeze atomic motion in the midst of chemical reactions.

Soft x-rays like those from ALS beamline 9.0.1 can also be made coherent, or laser-like, using a pair of pinholes. (The beam is conditioned by these pinholes, but they are not directly involved in imaging, except to make the beam laser-like.) To make a hologram, the beam issuing from the synchrotron scatters from the target object and is collected on a CCD detector. Meanwhile the same beam simultaneously passes through the multiple-pinhole URA, mounted on the same plate as the target object, and produces a bright reference beam.

The scattered image of the object and the many overlapping reference beams from the URA combine to make an interference pattern which contains all the information, including the relative depth of individual features, needed to mathematically reconstruct a three-dimensional image of the object.

The hologram of the Spiroplasma bacterium was made in precisely the same way, with much brighter x-ray beams and a much shorter pulse of light. So bright was the flash of light that the sample was vaporized, but not before both the scattered object beam and the reference beams from the URA had been recorded.

Together, the two experiments demonstrate that holographic x-ray images with nanometer-scale resolution can be made of objects measured in microns, in times as brief as femtoseconds. Moreover, sample preparation time is fast and easily repeated for high throughput during repetitive experiments. As the researchers write in their Nature Photonics article, Imaging with coherent x-rays will be a key technique for developing nanoscience and nanotechnology, and massively parallel holography will be an enabling tool in this quest.

This work was supported by grants from the U.S. Department of Energy, the European Union, the Swedish Research Councils, the Munich Centre for Advanced Photonics, the Natural Sciences and Engineering Research Council of Canada, and the Sven and Lilly Lawskis Foundation.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

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Increased Burden of Rare Genetic Variations Found in Schizophrenia

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 30 Jul 2008 20:11:10 +0000

For Immediate Release

Increased Burden of Rare Genetic Variations Found in Schizophrenia

Wednesday, July 30, 2008

Two New Sites of Deletions Implicated in Largest Study of its Kind

People with schizophrenia bear an increased burden of rare deletions and duplications of genetic material, genome-wide, say researchers supported in part by the National Institute of Mental Health (NIMH), a component of the National Institutes of Health (NIH).

Although many of us have these changes in our genetic material, they are about 15 percent more frequent in people with schizophrenia, explained Pamela Sklar, M.D., Ph.D., of Harvard University and the Stanley Center for Psychiatric Research. We also discovered two large areas of chromosomal deletions that confer a great deal of risk for schizophrenia and confirm involvement of a third previously reported area.

Sklar and colleagues in the International Schizophrenia Consortium team, representing 11 research institutes worldwide, report on the largest study of its kind to date, online July 30, 2008, in the journal Nature.

By implicating two previously unknown sites, this study triples the number of genomic areas definitely linked to schizophrenia, said NIMH Director R Thomas Insel, M.D. It also confirms in a large sample that unraveling the secrets of rare structural genetic variation may hold promise for improved diagnosis, treatment and prevention of such neuro-developmental disorders.

Although recent smaller studies had identified such structural genetic glitches in schizophrenia, this genome-wide association study is the first large enough to detect weak signals that might otherwise be drowned out amid a din of statistical noise. Genetic factors are thought to account for 73 to 90 percent of schizophrenia, but most of these have so far eluded detection.

In search of rare illness-linked genetic variations, Sklar and colleagues scanned the genomes of 3,391 schizophrenia cases and 3,181 controls in a European sample.

The cases showed a subtle, but statistically significant increased number of such variations, which were found in 13.1 percent of cases and 10.4 percent of controls. Variations affected 1.41-fold more genes in people with schizophrenia, who also had a 1.45-fold higher prevalence of the rarest glitches those that occurred only once.

The large sample also allowed the researchers to pinpoint previously undiscovered chromosomal locations associated with schizophrenia. An area on Chromosome 15 harbored deletions in 9 cases and no controls, while an area on Chromosome 1 had deletions in 10 cases and only one control.

This tells us that variations in both of these areas are very potent risk factors for schizophrenia, said Sklar.

The researchers also confirmed in 13 cases a previously-reported association between schizophrenia and a deletion on chromosome 22 known to cause velo-cardio-facial syndrome. Other suspect sites identified were on Chromosomes 12 and 16 and in genes relevant to neural development and growth.

Exactly how the subtly increased number of structural variations in schizophrenia might translate into illness remains to be discovered, say the researchers.

The same sites of deletions on Chromosomes 1 and 15 reported by Sklar and colleagues, as well as an additional area on Chromosome 15, were also implicated in schizophrenia by another large study published online the same day in Nature by another international group of researchers supported in part by NIMH.

The International Schizophrenia Consortium is composed of researchers at: Cardiff University, Karolinska Institute/University of North Carolina at Chapel Hill, Trinity College Dublin, University College London, University of Aberdeen, University of Edinburgh, Queensland Institute of Medical Research, University of Southern California, Massachusetts General Hospital, Stanley Center for Psychiatric Research and Broad Institute of MIT and Harvar

Permalink: http://www.sflorg.com/comm_center/medical/p486_24.html

Time Stamp: 7/30/2008 at 7:35:12 PM UTC

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New Insight on Superconductors

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 30 Jul 2008 19:04:38 +0000

For Immediate Release

New Insight on Superconductors

Wednesday, July 30, 2008

An important advance in understanding how the electrons in some materials become superconducting has been made by researchers from UC Davis, the Los Alamos National Laboratory and UC Irvine. The work, published July 31 in the journal Nature, could lead to a deeper understanding of superconductivity and to new materials that are superconducting at higher temperatures.

The team of researchers, led by Yi-feng Yang, a postdoctoral fellow at UC Davis, found a simple way to calculate the temperature at which a new state of matter, the Kondo liquid, emerges in the class of metal alloys called heavy-electron materials. At very low temperatures, these alloys can become superconductors that conduct electricity without resistance.

"We've found a framing concept for an important class of materials, which allows us to begin to understand how they relate to each other and perhaps to find new members of the group," said Yang's postdoctoral mentor and team member, David Pines, distinguished professor of physics at UC Davis and co-director of ICAM, the Institute for Complex Adaptive Matter.

Heavy electron materials are alloys of metals such as cerium, ytterbium and uranium. They contain both free-moving electrons that make them electrical conductors and a "Kondo" lattice of localized electrons. When the temperature of the material is lowered below a characteristic temperature, the localized electrons lose their magnetism as they become collectively "entangled" through quantum mechanical effects with the conduction electrons, which become heavy and form the Kondo liquid. At much lower temperatures these heavy electrons then become either magnetic or superconducting.

Yang received a fellowship from ICAM that enabled him to become "embedded" in an experimental group on heavy electron materials led by Joe D. Thompson at Los Alamos. With Thompson and Han-oh Lee at Los Alamos, and Zachary Fisk at UC Irvine, he reviewed 30 years of existing data on heavy-electron materials, plus new experimental data collected by Thompson and Lee, to establish a long-sought connection between single impurities and lattice behavior in these materials.

They found that the crucial temperature at which the Kondo liquid emerges depends in a remarkably simple way on the coupling of individual local spins to the conduction electrons, Pines said.

The discovery should help researchers find the organizing principles of heavy-electron superconductivity, because it clarifies the nature of the normal state out of which superconductivity emerges, Pines said.

The work was supported by the National Science Foundation and by the ICAM fellowship for Yang. ICAM is a multidisciplinary research program of the University of California that has 57 branches across the U.S. and globally, with its headquarters at UC Davis.

Permalink: http://www.sflorg.com/comm_center/unv_tech/p485_40.html

Time Stamp: 7/30/2008 at 6:33:07 PM UTC

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KFC DNA disproves Pacific migration

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 30 Jul 2008 16:21:42 +0000

For Immediate Release

KFC DNA disproves Pacific migration

July 30, 2008

A study of DNA from ancient and modern chickens has shed light on the controversy about the extent of pre-historic Polynesian contact with the Americas.

There has been much debate about the idea that Polynesians introduced chickens into South America in pre-Columbian times, and that resulting indigenous Amerindian chickens were the ancestors of several distinctive breeds found in Chile today. In contrast, the conventional idea is that the ancestors of these birds were introduced from Europe by the Spanish in the 15th century.

A recent study claimed to have found the first direct evidence of a genetic link between ancient Polynesian and apparently pre-Columbian chickens from archaeological sites, supporting the concept of more extensive contact between Polynesia and South America. However, the current study reveals that this claim was based on erroneous analyses.

Project leader, Colombian-born researcher Dr Jaime Gongora, says "Some people in South America like to believe they are descendants of Polynesians. This study does not disprove this idea, but we found no evidence to support pre-historic contact."

Dr Gongora works in the field of animal genetics in the Faculty of Veterinary Science at the University of Sydney, and leads an international team including ancient-DNA experts from the ACAD University of Adelaide as well as other institutions from Australia, Kenya, China, the United Kingdom and Sweden.

Taking DNA samples from 41 native Chilean chicken specimens, researchers compared them with 1000 DNA samples from domestic chickens from around the world and with the genetic DNA samples taken from a pre-Columbian site in Chile, and ancient DNA sequences from chickens in Polynesia.

The results of the work revealed that the mitochondrial DNA from modern indigenous and archaeological Chilean chickens, and several archaeological specimens from Polynesia, were not a unique match as had been claimed, but were in fact identical to the most common chicken DNA in the world today. This suggests the Chilean birds are descended from early Spanish domestic breeds, and that there is no support for contact between Polynesian and pre-Columbian people. This study does not disprove the Polynesian/pre-Columbian contact, but that authors found no DNA evidence under the Storey et al paper to support pre-historic contact so more research is needed.

The study 'Indo-European and Asian origins for Chilean and Pacific chickens revealed by mtDNA' has been published in the prestigious journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Dr Gongora's current areas of interest also include phylogeography, retroviruses and immunogenetics of crocodiles, platypus, pigs and peccaries

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Ocean Surface Topography Mission/Jason 2 Begins Mapping Oceans

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 30 Jul 2008 14:55:41 +0000

For Immediate Release

Ocean Surface Topography Mission/Jason 2 Begins Mapping Oceans

July 30, 2008

Less than a month after launch, the NASA-French space agency Ocean Surface Topography Mission (OSTM)/Jason 2 oceanography satellite has produced its first complete maps of global ocean surface topography, surface wave height and wind speed.

The new data will help scientists monitor changes in global sea level and the distribution of heat in the ocean. This information is used to monitor climate change and ocean circulation, and to enable more accurate weather, ocean and climate forecasts. The data reveal patterns of sea level anomalies, which are used by scientists to calculate the speed and direction of ocean surface currents.

The new mission extends a 16-year continuous record of global sea level measurements begun in 1992 by the NASA/Centre National d'Etudes Spatiales (CNES) Topex/Poseidon mission and continued by the two agencies on Jason 1, launched in 2001. Data from Topex/Poseidon and Jason 1 show that mean sea level has been rising by about three millimeters (.12 inches) a year since 1993.

The new maps were generated from the first 10 days of data collected once the new satellite, OSTM/Jason 2, reached its operational orbit of 1,336 kilometers (830) miles on July 4. The new satellite and its predecessor, Jason 1, are now flying in formation in the same orbit approximately 55 seconds apart, making nearly simultaneous measurements that are allowing scientists to precisely calibrate the new satellite's instruments. Comparisons of data from the two satellites on sea-level anomalies, significant wave height and ocean wind speed all show very close correlation of all measured parameters.

"These initial observations from OSTM/Jason 2 compare very closely to those of Jason 1," said Lee-Lueng Fu, OSTM/Jason 2 project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "To be able to collect such high-quality science data within a month of launch breaks previous records. It is also a direct reflection of how mature the field of satellite altimetry has become and of the seamless cooperation of our international team."

The satellite's first radar altimeter data were acquired just 48 hours after its launch on June 20 from Vandenberg Air Force Base, Calif., on a Delta II rocket. The French space agency processed the first test results, followed by more advanced data results a week after launch. The more advanced results came after calculating the precise location of the satellite's preliminary orbits. The satellite, its instruments and ground segment are all functioning properly. Once it has been fully calibrated and validated, the satellite will begin providing oceanographic products to users around the world.

OSTM/Jason 2 is an international endeavor, with responsibilities for satellite development and launch shared between NASA and CNES. CNES provided the OSTM/Jason 2 spacecraft, NASA provided the launch, and NASA and CNES jointly provided the primary payload instruments. CNES and the U.S. National Oceanic and Atmospheric Administration (NOAA) are responsible for satellite operations, while JPL is managing the mission for NASA. Data processing is being carried out by CNES, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and NOAA, depending on the type of product.

Once on-orbit commissioning of OSTM/Jason 2 is completed, CNES will hand over mission operations and control to NOAA, which will then join with EUMETSAT to generate, archive and distribute data products to users worldwide.

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Cracking the Secrets of Ice

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Fri, 25 Jul 2008 14:29:09 +0000

For Immediate Release

Cracking the Secrets of Ice

Friday, July 25, 2008

Sandia researchers successfully image ice using scanning tunneling microscope

Taking images of ice a few nanometers thick as it forms bulk ice was supposed to be impossible. A scanning tunneling microscope (STM) shouldn't work with ice because STMs create images by relying on conducting current, which runs contrary to one of ice's basic properties -- insulation.

But that -- successfully using an STM to image ice -- is precisely what Sandia National Laboratories physicists Norm Bartelt and Konrad Thurmer did.

"How water interacts with solids is extremely important," says Bartelt. He points to the design of fuel cells and water purification systems as two areas that could benefit from new STM information. "Getting direct information is difficult, so imaging how small ice crystals grow on solid surfaces is an important advance. This is solid information that allows basic theories to be verified. This was our goal -- to provide unambiguous information."

Ice Cubes or Snowflakes?
Bartelt's and Thurmer's research was motivated by Sandia colleague Peter Feibelman's theoretical research in water -- solid interactions. In 2002, Feibelman had a major breakthrough in interpreting water -- solid interactions. His research explained why an initial layer of water molecules lies flat on the precious metal ruthenium.

The ice-growth images answer a fundamental mystery about ice: snowflakes form in the classic six-sided symmetrical shape, but at low temperatures, ice grows in a cubic form. This phenomenon is something that has puzzled scientists for 60 years.

What Bartelt and Thurmer discovered was that when an ice film is extremely thin, measuring an average of about one nanometer thick, the water molecules form small, tabular islands of crystalline ice. Once the thickness reaches four or five nanometers, the ice islands join together and start to form a continuous film. In a recent Physical Review B paper, the researchers showed that cubic ice forms when the ice crystals merge. Because of a mismatch in the atomic step heights of the platinum substrate relative to ice, the coalescence often creates screw dislocations in the ice. Further growth occurs by water molecules attaching to the steps that spiral around screw dislocations, creating cubic ice in the process.

Pushing the Boundaries of STM
The STM is a notoriously finicky piece of scientific equipment, and working with ice only increased the difficulty. An STM functions by positioning a sharp, needle-like tip near the sample and then allowing a tiny electrical current to flow across the gap. As the tip of the STM is scanned across the sample surface, the voltage required to position the scanner is used to form an image of the sample.

"Typically, an STM only works if the substrate is conductive," says Bartelt. Through persistence and patience, Thurmer learned that to image ice, one needs a current smaller than had previously been tried -- in fact, three orders of magnitude smaller than what is normally used.

It was Thurmer's intuitive decision to change the STM's parameters, namely those for voltage and current, that made imaging ice crystals feasible. Basically, Thurmer found the sweet spot where none was believed to have existed.

The STM was developed in 1981 and earned its inventors, Gerd Binnig and Heinrich Rohr, a Nobel Prize for physics in 1986. "The discovery caused a rebirth of surface science and completely changed the field, but until now, people had not been able to apply it to ice," says Bartelt. "The fact that we can apply these same methods to ice is very exciting."

STM experiments don't always work. "Because you are trying to get atomic resolution, a few atoms on the apex of the tip can completely throw off the experiment," says Bartelt. "If you are not getting an image, you don't know if your tip is bad or you are choosing the wrong parameters."

In fact, the two physicists never expected that they could image thick ice films; they were hoping for a few molecules. Thurmer explains that even after he began imaging thicker ice films, he didn't trust the results. Instead, he thought they were just misleading electronic artifacts.

Because Thurmer only expected to see films a few molecules thick, he had the STM tip set too close; it was shaving off the top of the films. "For about a month, we thought the films were not really as high as they seemed. We thought the insulating quality of ice made them appear to be higher," he explains. "I increased the voltage, and the ice appeared to really pop out. Still, I thought it was just the same electronic artifact."

However, the researchers could not come up with another explanation for why the films appeared so high. Thurmer then purposely grew very thick films and reversed the polarity on the STM, which resulted in an ice carving that proved the thickness was, in fact, real.

The two Sandians are not resting on their initial success; in fact, the two physicists say they are working to build on their breakthrough. Future experiments include putting salts on an ice crystal to see how salts change the crystal's growth and depositing molecules that react with water, such as atomic oxygen, to determine the exact point on the surface where water dissociates.

"Our ability to image these ice films opens the door to a multitude of exciting new experiments," says Thurmer.

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Researchers Discover Key Gene for Making Motor Neurons

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Fri, 25 Jul 2008 13:40:43 +0000

For Immediate Release

Researchers Discover Key Gene for Making Motor Neurons

Friday, July 25, 2008

Simple, everyday movements require the coordination of dozens of muscles, guided by the activity of hundreds of motor neurons. Now, researchers have revealed an important step in the process that guides the early development of neurons themselves, as they establish the precise connections between the spinal cord and muscles. This knowledge will help scientists search for drugs to treat diseases that destroy motor neurons, such as amyotrophic lateral sclerosis, or Lou Gehrig's disease.

As a vertebrate organism develops, the long, outstretched processes of motor neurons wend their way from the spinal column to wire up every muscle in the body. In mammals, many hundreds of different types of motor neurons are needed to control the variety of muscle types used to coordinate movement. The highly specialized motor neurons that innervate muscles in the arms, legs, hands, and feet are the most recent of these to evolve. As an animal develops, these neurons become increasingly specialized - first establishing themselves as motor neurons, then taking on the characteristics needed to control a limb, then preparing to target a specific muscle. Proper function depends on each of these neurons finding its way from the spinal cord to the group of muscle cells that it is equipped to control.

"It is a complicated but satisfying genetic logic, one that appears to have evolved to ensure the generation of the diverse array of motor neuron subtypes needed for fine motor control of the limbs."
Thomas M. Jessell

Now, Howard Hughes Medical Institute investigator Thomas M. Jessell, working together with Jeremy Dasen of New York University and Philip Tucker of The University of Texas at Austin, has discovered the genetic recipe for making these specialized motor neurons. The key ingredient is a gene called Foxp1, which regulates the activity of a series of crucial patterning genes of the Hox family, and thereby coordinates the identity and connectivity of motor neurons. Without FoxP1, the axons of motor neurons that extend into an animal's limb wander aimlessly and connect to muscles at random, Jessell and Dasen have found. The paper describing these findings is published in the July 25, 2008, issue of the journal Cell.

The Hox genes are among the most highly conserved of the developmental genes and are best known for their role in controlling the overall pattern of body development. Like many developmental regulators, the proteins produced by Hox genes control the activity of a diverse assortment of target genes. In previous work, Jessell, who is at Columbia University Medical Center, and Dasen discovered that 21 of the 39 mammalian Hox genes orchestrate the program of motor neuron development and connectivity. Their new work shows that FoxP1 is an essential co-factor for the entire set of Hox proteins that generate the motor neurons that control limb movement. Intriguingly, the level of FoxP1 expressed by developing motor neurons determines the precise subtype that they will form.

"This paper makes the surprising discovery that one accessory co-factor, FoxP1, is needed for the output of each of the 21 Hox proteins that make motor neurons different," says Jessell. "Depending on which Hox gene is turned on, FoxP1 is induced to different levels. And this difference in level programs which motor neuron subtype is generated. It is a complicated but satisfying genetic logic, one that appears to have evolved to ensure the generation of the diverse array of motor neuron subtypes needed for fine motor control of the limbs."

To emphasize the importance of this highly-evolved class of motor neurons, Jessell points to a relatively primitive vertebrate, the eel-like jawless fish known as a lamprey. "Lampreys don't play the violin and they don't run - their motor programs are designed for simple swimming behaviors," Jessell says. "The lamprey represents the most extreme example of vertebrate organisms whose lifestyle permits them to survive with a highly reduced array of motor neuron subtypes.

"At some point in evolution, vertebrates acquired the ability to generate hundreds of motor neuron subtypes, presumably to accommodate the appearance of limbs new muscle classes," says Jessell. He and his colleagues suspect this diversity may have arisen when FoxP1 began to be expressed in the spinal cord But exactly when FoxP1 expression first appeared in the spinal cord and how its expression is linked to Hox activities remain unsolved puzzles that Jessell and Dasen are now pursuing. Together with Sten Grillner of the Karolinska Institute and Manuel Pombal of the University of Vigo in Spain, they are beginning these studies by analyzing the expression and function of the FoxP1 gene in lampreys.

Jessell, Dasen, and Tucker demonstrated the significance of FoxP1 in mice by inactivating the gene and showing that the spinal cord lacked the full repertoire of motor neurons without it. "This mutation, in effect, reverts the spinal cord to a primitive ancestral state, generating a lamprey-like spinal cord encased in a mammalian body," Jessell says. Mice without FoxP1 die before birth because the gene is also critical for heart development, so the scientists are now analyzing genetically-modified mice in which FoxP1 is deleted selectively from motor neurons. "We anticipate that these animals will have a severe impairment in motor behavior, and studying later phases of FoxP1 function should reveal insights into the assembly of motor circuits in the spinal cord as well as the periphery" he says.

Jessell's Columbia colleagues Hynek Wichterle and Mirza Peljto, in work supported by ProjectALS, are already using the Fox-Hox recipe in their attempts to create better ways of screening for drugs to treat Lou Gehrig's disease and other types of motor neuron degeneration. Fine-tuning the expression of the these proteins has recently permitted Wichterle and Peltjo to convert embryonic stem cells into the highly-specialized motor neurons that innervate limb muscles.

"This is a promising screening strategy for identifying drugs that prevent or slow the degeneration of motor neurons," says Jessell. "Hopefully, many researchers will build upon these advances in basic motor neuron biology to design better and more predictive therapeutic screens."

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'Nanonet' circuits closer to making flexible electronics reality

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 23 Jul 2008 17:59:05 +0000

For Immediate Release

'Nanonet' circuits closer to making flexible electronics reality

Wednesday, July 23, 2008

Researchers have overcome a major obstacle in producing transistors from networks of carbon nanotubes, a technology that could make it possible to print circuits on plastic sheets for applications including flexible displays and an electronic skin to cover an entire aircraft to monitor crack formation.

The so-called "nanonet" technology - circuits made of numerous carbon nanotubes randomly overlapping in a fishnet-like structure - has been plagued by a critical flaw: The network is contaminated with metallic nanotubes that cause short circuits.

The discovery solves this problem by cutting the nanonet into strips, preventing short circuits by breaking the path of metallic nanotubes.

"This is a fundamental advance in how nanotube circuits are made," said Ashraf Alam, a professor of electrical and computer engineering at Purdue University. He is working with Kaushik Roy, Purdue's Roscoe H. George Professor of Electrical and Computer Engineering, and doctoral students Ninad Pimparkar and Jaydeep P. Kulkarni.

Researchers at the University of Illinois at Urbana-Champaign led experimental laboratory research to build the circuits, and Purdue led research to develop and use simulations and mathematical models needed to design the circuits and to interpret and analyze data.

Findings will be detailed in a research paper appearing in the journal Nature on July 24. The paper was written by the Purdue engineers and University of Illinois researchers : John A. Rogers, Founder Professor of Materials Science and Engineering and a professor of chemistry; Moonsub Shim, Racheff Assistant Professor of Materials Science and Engineering; and doctoral students Qing Cao, Hoon-sik Kim and Congjun Wang.

"These findings represent the culmination of four years of collaborative efforts between the Illinois and Purdue groups," Rogers said. "The work established the fundamental scientific knowledge that led to this particular breakthrough and the ability to make circuits."

The nanonets are made of tiny semiconducting cylinders called single walled carbon nanotubes. Metallic nanotubes form unavoidably during the process of making carbon nanotubes. These metal tubes then link together in meandering threads that eventually stretch across the width of the transistor, causing a short circuit.

"Other researchers have proposed eliminating the metallic nanotubes," Rogers said. "Instead, we found a very nice way of essentially removing the effect of these metallic nanotubes without actually eliminating them."

The researchers created a flexible circuit containing more than 100 transistors, the largest nanonet ever produced and the first demonstration of a working nanonet circuit, Alam said.

"Now there is no fundamental reason why we couldn't develop nanonet technologies," he said. "If you can make a flexible circuit with 100 transistors, you can make circuits with 10,000 or more transistors."

The advance may allow researchers to use carbon nanotube transistors to create high-performance, shock-resistant, lightweight and flexible integrated circuits at low cost, Alam said.

A key advantage of the nanonet technology is that it can be produced at low temperatures, enabling the transistors to be placed on flexible plastic sheets that would melt under the high temperatures required to manufacture silicon-based transistors, he said.

Possible applications include an electronic skin that covers an aircraft and automatically monitors the formation of cracks to alert technicians and prevent catastrophic failures.

Such shape-conforming electronics are not possible using conventional silicon-based circuits, which are manufactured on rigid wafers or glass plates.

"Now electronics are flat, which limits their utility since most objects in real life are not flat," Roy said.

Flexible displays could be integrated into automotive windshields to provide information for drivers. Other potential applications include "electronic paper" that displays text and images, solar cells that could be printed on plastic sheets and television screens capable of being rolled up for transport and storage.

"For these types of applications, manufacturers might literally print, or stamp, circuits onto plastic sheets, like the roll-to-roll printing used to print newspapers," Alam said.

Conventional circuits for flat-panel televisions contain transistors made of materials called polysilicon or amorphous silicon, which cannot be used in flexible applications.

Nanonet transistors are promising for so-called macroelectronics because they are best suited for large-scale applications, but these transistors may not be as well suited for the requirements of microelectronic circuits, such as those in computer chips, Alam said.

The nanotubes are arranged randomly and overlap each other like tiny needles. If the nanonet area is large enough, the overlapping metallic nanotubes will eventually form a meandering string across the entire transistor, causing a short circuit. But if the device is segmented into strips, this meandering path of metallic rods is cut at the point where the lines separate one strip from another, preventing short circuits.

The metallic nanotubes make up about one-third of the nanotubes in the transistor. Because the carbon nanotubes are twice as numerous as the metallic tubes, enough of them exist to form a complete circuit. The models and simulations are needed to tell researchers precisely how wide to make the strips so that the pathway of metallic tubes is cut but the carbon nanotubes complete their circuit.

"The theory and simulation work done at Purdue shows there is always a way to break the metallic path and still keep the semi conducting carbon-nanotube path intact," Alam said. "The teams at Illinois and Purdue continuously provide insights about why things work the way they do and how to make them work better through combined modeling and experimental efforts."

Each nanonet transistor consists of numerous strips of nanotubes, separated bylines that are etched in place. The lines are easy to create with a standard etching process used in the semiconductor industry.

Future research may include work focusing on learning the reliability of the carbon nanotube circuits.

The research has been funded by the National Science Foundation through the Network for Computational Nanotechnology at the Birck Nanotechnology Center in Purdue's Discovery Park. The Illinois portion of the research also was funded and supported by the NSF, U.S. Department of Energy, Motorola Corp., and by the university's Frederick Seitz Materials Research Lab, the Center for Microanalysis of Materials and the Department of Chemistry.

The researchers used computers made available by a global network called the nanoHUB, an Internet-based science gateway that provides computer-based resources for research and education in the areas of nanoelectronics and nanoelectromechanical systems and their application to nano-biosystems.

"This work requires tremendous computing resources because these are not trivial calculations," Alam said.

Nanoelectronics focuses on creating a class of electronic devices containing features measured in nanometers, equivalent to one-billionth of a meter. A nanometer is about the size of 10 atoms strung together.

The Network for Computational Nanotechnology uses advanced theory and simulations to explore new ideas for digital switching devices such as innovative types of transistors that promise to help researchers create future electronics.

The research is complementary to work by Purdue researcher David Janes, a professor of electrical and computer engineering. His work involves transparent circuits using a different type device called nanowires, made of indium oxide instead of carbon nanotubes.

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Making Patients Move Requires the Right Exercise Advice

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 23 Jul 2008 17:20:16 +0000

For Immediate Release

Making Patients Move Requires the Right Exercise Advice

Wednesday, July 23, 2008

MU professor says behavior strategies, such as goal setting, motivate patients

It is common knowledge that regular exercise supports physical and mental well-being. Despite this and recommendations from health care providers, the majority of patients with chronic illnesses remain inactive. In a new study, University of Missouri researchers found that adults with chronic illness who received interventions focused on behavior-changing strategies significantly increased their physical activity levels. In contrast, interventions based on cognitive approaches, which attempt to change knowledge, beliefs and attitudes, and are most commonly used by health care providers, did not improve physical activity.

"The information that physicians are giving patients isn't working. Patients are not motivated when they hear 'exercise is good; it will improve your health.' What works is providing patients with simple, action-orientated strategies to increase their activity levels," said Vicki Conn, professor and associate dean of research in the MU Sinclair School of Nursing.

Behavior strategies include feedback, goal setting, self-monitoring, and stimulus or cues. Self-monitoring, any method where participants record and track their activity over time, significantly increased awareness and provided motivation for improvement, Conn said.

"It is important for care providers to set very specific, manageable goals with patients," Conn said. "For example, ask them to exercise for 20 minutes, three times a week and track their progress by writing it down. Have them schedule exercise on their calendars, or prompt them by setting their walking shoes by their doors. Ask how they can reward themselves if they accomplish the goal. This will help incorporate activity into their daily routines and provide them with a sense of accomplishment."

Conn completed a meta-analysis incorporating data from 22,527 participants in 163 research reports. No previous analysis has examined physical activity levels following interventions among adults with diverse chronic illnesses. Conn found that interventions were similarly effective regardless of gender, age, ethnicity and socioeconomic status.

"Behavior interventions increased participants' activity by an average of 48 minutes per week, which is enough to provide them with health benefits," Conn said. "People may feel overwhelmed by the thought of exercise, or think they have to work out 60 minutes, five days a week, but doing just 12 minutes per day may get them started toward better health."

The study "Meta-Analysis of Patient Education Interventions to Increase Physical Activity Among Chronically Ill Adults," was published in Patient and Education Counseling. Conn's research is funded by a more than $1 million grant from the National Institutes of Health.

Permalink: http://www.sflorg.com/comm_center/unv_medical/p483_101.html

Time Stamp: 7/23/2008 at 4:46:05 PM UTC

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Ancient Galactic Magnetic Fields Stronger than Expected

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 23 Jul 2008 15:40:06 +0000

For Immediate Release

Ancient Galactic Magnetic Fields Stronger than Expected

Wednesday, July 23, 2008

Mining the far reaches of the universe for clues about its past, a team of scientists including Philipp Kronberg of Los Alamos National Laboratory has proposed that magnetic fields of ancient galaxies like ours were just as strong as those existing today, prompting a rethinking of how our galaxy and others may have formed.

With powerful telescopes and sophisticated measurements, the team probed back in time to see the ancient universe as it existed some 8 to 9 billion years ago. Their research was published in the July 17 edition of Nature.

Until now, a prevailing view in the astrophysical community has been that galactic magnetic fields gradually increased over cosmic time up to their present strengths and that in the nascent universe, magnetic fields were initially very weak. Astrophysicists explain this gradual growth of magnetism over time with the large-scale "galactic dynamo" model.

The letter in the current issue of Nature extends a parallel, larger study by Kronberg et al. of early magnetic fields from the March 2008 edition of The Astrophysical Journal. That study, whose contributors also included LANL colleagues David Higdon and Margaret Short, relied mostly on Faraday rotation measures (RM) taken at radio wavelengths, beyond what is visible to the human eye.

By measuring how far the radio waves were pulled toward the red end of the spectrum-known as "redshift"-Kronberg and his colleagues homed in on the location of magnetic fields in the distant universe.

What allowed the team to take a more detailed look at the ancient universe in this Nature letter was the addition of high-resolution optical spectra by Martin Bernet, Francesco Miniati, and Simon Lilly at the ETH Zürich (the Swiss Federal Institute of Technology) from the European Southern Observatory's 8-meter telescope, located in Chile's Atacama Desert. Their measurements at optical wavelengths of more than 70 quasars were combined with the RM data Kronberg has been collecting for more than 25 years - data based on accurate radio RM measurements from several of the world's most powerful radio telescopes, including the Very Large Array near Soccoro, New Mexico, and the 100-meter dish in Effelsberg, Germany.

"It was thought that, looking back in the past, earlier galaxies would not have generated much magnetic field," Kronberg said. "The results of this study show that the magnetic fields within Milky Way-like galaxies have been every bit as strong over the last two-thirds of the Universe's age as they are now-and possibly even stronger then."

Serving as a looking glass into the past, the powerful telescope at the European Southern Observatory, adding to the radio RM data, allowed the scientists to make observations of high magnetic fields between 8 billion and 9 billion years ago for 70 intervening galaxies whose faint optical absorption spectra revealed them as "normal" galaxies. That means that several billion years before the existence of our own sun, and within only a few billion years of the Big Bang, ancient galaxies were exerting the tug of these strong magnetic fields.

This research suggests that the magnetic fields in galaxies did not arise due to a slow, large-scale dynamo effect, which would have taken 5 billion to 10 billion years to reach their current measured levels. "There must be some other explanation for a much quicker and earlier amplification of galactic magnetic fields," Kronberg said. "From the time when the first stars and galaxies formed, their magnetic fields have probably have been amplified by very fast dynamos. One good possibility is that it happened in the explosive outflows that were driven by supernovae, and possibly even black holes in the very earliest generations of galaxies."

This realization brings a new focus on the broader question of how galaxies form. Instead of the commonly held view that magnetic fields have little relevance to the genesis of new galaxies, it now appears that they are indeed important players. If so, strong magnetic fields a long time ago are one of the essential ingredients that explain the very existence of our galaxy and others like it.

Permalink: http://www.sflorg.com/comm_center/space/p482_07.html

Time Stamp: 7/23/2008 at 3:32:25 PM UTC

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Dinosaurrific!

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 23 Jul 2008 15:09:17 +0000

For Immediate Release

Dinosaurrific!

Wednesday, July 23, 2008

New Dinosaur Supertree -- the most comprehensive picture ever produced of how dinosaurs evolved.

It has long been debated whether dinosaurs were part of the "Terrestrial Revolution" that occurred some 100 million years ago during the Cretaceous when birds, mammals, flowering plants, insects and reptiles all underwent a rapid expansion.

An international study, led by the University of Bristol, shows that during their last 50 million years of existence, dinosaurs were not expanding as actively as had been previously thought and that the apparent explosion of dinosaur diversity may be largely explained by sampling bias.

The team produced a 'supertree' of dinosaurs, showing the most likely pattern of evolution for 440 of the 600 known species of dinosaur. "Supertrees are very large family trees made using sophisticated computer techniques that carefully stitch together several smaller trees which were previously produced by experts on the various subgroups", explained lead author Graeme Lloyd.

"Our supertree summaries the efforts of two decades of research by hundreds of dinosaur workers from across the globe and allows to look for unusual patterns across the whole of dinosaurs for the first time." It is the most comprehensive picture ever produced of how dinosaurs evolved. The results are published today (23 July) in the Proceedings of the Royal Society B.

Professor Mike Benton from Bristol University said: "It's not complete, but it's the most detailed and comprehensive single evolutionary tree produced for dinosaurs, and indeed for almost any other group.

"Up until now, most studies of the evolution of dinosaurs were not tested numerically against an accurate and comprehensive database. We hope our study will mark the first of a new wave of such thorough, quantitative studies in palaeontology."

The new study uses statistical techniques to distinguish unusually high rates of diversification from normal rates. The results show that all the bursts of diversification happened in the first fifty million years of the evolution of dinosaurs. Later expansions were not distinguishable from normal rates. This suggests dinosaurs did not take advantage of the new food supplies available during the Cretaceous Terrestrial Revolution -- such as flowering plants, lizards, snakes, birds and mammals.

The work was done using the High Performance Computing facilities of the National University of Ireland, Maynooth. It was based on a combination of 155 published dinosaur "trees" and took approximately 5,000 hours of calculation time.

The key focus was to see whether dinosaurs had been part of a major phase of evolution on land -- the Cretaceous Terrestrial Revolution (between 125 - 80 million years ago) -- when many new groups of plants and animals expanded rapidly. During this time, the flowering plants and social insects arose and became more and more common. Many backboned animals also expanded to take advantage of the new sources of food.

Visit Dinosaur Supertree Website: http://palaeo.gly.bris.ac.uk/supertree/

Permalink: http://www.sflorg.com/comm_center/unv_science/p481_127.html

Time Stamp: 7/23/2008 at 2:44:10 PM UTC

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No sex please, we're insect pests

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Wed, 23 Jul 2008 14:27:55 +0000

For Immediate Release

No sex please, we're insect pests

July 23, 2008

A new study has found that agricultural environments drive insects to reproduce without sex - a trait that is uncommon in most of the animal kingdom - but may provide methods for controlling their damaging effects.

Researchers at the University of Melbourne have found that when insect pests have a stable environment with abundant resources - such as grain crops, orchards, vineyards, pastures and plantations where the same crops are grown every season - they were four times more likely to reproduce without sex compared to insects overall.

"So increasing the complexity and variability of agricultural environments provides a way of potentially controlling asexual pest species" said Professor Ary Hoffmann from the Center for Environmental Stress and Adaptation Research at the University of Melbourne.

These pests include species like aphids that suck sap, mites that eat leaves, scale insect pests that feed on plant sap, beetles that eat plants and thrips that puncture plant cells.

"We looked at insects from Italy and North America, comparing databases of agricultural pest species with the insect species that can reproduce asexually - a method that is effectively cloning and so doesn't require males and sex for reproduction".

"We discovered that the asexual species comprised 45% (North America) or 48% (Italy) of pest species in genera where asexual reproduction occurred, compared to an overall incidence of 10% or 16% in these genera".

"The advantage farmers have is that asexual pests will have difficulty overcoming control methods that require the evolution of changes at multiple genes, which is more easily achieved with sexual reproduction where two sets of genes combine to produce a more variable genetic make-up than just cloning," added Dr Andrew Weeks from the department of Genetics at the University of Melbourne.

This means that asexual pests should be slower at adapting and becoming resistant to chemical controls, and should be susceptible to biological controls such as fungi that can be released like pesticides.

Asexual pests will also find it harder to adapt to new varieties of plants bred to be resistant to pests, as long as the resistance mechanisms involve several genes.

"Asexual reproduction may be favored in agricultural environments when particular clones are selected in the same stable environment across multiple generations. Asexual reproduction may also be favored as populations can be initiated by single individuals whereas sexual species require the presence of males and females".

"Another factor is that in agricultural ecosystems, sexual reproduction cues may be absent".

Researchers found that the high incidence of asexual reproduction in pest species is spread across different families and several insect orders.

The study was published online this week in the journal Proceedings of the Royal Society B.

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Outdoor enthusiasts scaring off native carnivores in parks

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 22 Jul 2008 17:07:27 +0000

For Immediate Release

Outdoor enthusiasts scaring off native carnivores in parks

Tuesday, July 22, 2008

Even a quiet stroll in the park can dramatically change natural ecosystems, according to a new study by conservation biologists from the University of California, Berkeley. These findings could have important implications for land management policies.

The study compared parks in the San Francisco Bay Area that allow only quiet recreation such as hiking or dog walking with nearby nature reserves that allow no public access. Evidence of some native carnivore populations - coyote and bobcat - was more than five times lower in parks that allow public access than in neighboring reserves where humans don't tread, the researchers report.

The dearth of these animals in the parks carries implications beyond just these species. Since the carnivores in the study are often the top predators in their areas, these animals also shape the rest of their surrounding ecosystems. The flight of large animals from heavily visited parks for more serene surroundings could, in turn, influence populations of small animals and plants, the researchers said.

"Carnivores are sensitive indicators of human disturbance," said Sarah Reed, postdoctoral scholar in UC Berkeley's Department of Environmental Science, Policy and Management and the study's lead author. "Their presence or absence can be a good, early clue to how the ecosystem is doing."

Unexpected findings

To measure carnivore numbers, Reed studied the droppings of six native and non-native mammalian carnivores in 28 parks and preserves in northern California. The parks in her study allow public access, but don't allow motorized vehicles or hunting and fishing. Most visitors to these parks hike or walk their dogs, Reed said. The preserves in the study have limited or no public access.

Reed found more than five times as much coyote and bobcat scat in preserves with no public access than she did in the parks. Coyotes and bobcats are both native carnivores. She also found more scat from the native gray fox and the non-native red fox in unvisited areas, and more dog and cat droppings in visited parks.

Reed said she did not expect these findings. She and many other conservation biologists assumed that activities such as hiking or horseback riding were relatively benign, she said. "I was surprised that the difference was so dramatic," Reed said.

Adina Merenlender, cooperative extension specialist in the Department of Environmental Science, Policy and Management and senior author on the study, said the findings "are probably the most surprising results that have come out of my lab to date."

The differences in carnivore populations are even more surprising when you consider that these animals are most active at night, dawn and dusk, and that people visit parks during the day, Reed said. "We assumed that carnivores and people were avoiding each other in time and space," she said.

Reed was initially conducting a different study on carnivores when she realized that the differences in their numbers between sites with and without public access were so large that they obscured the data she was looking for. "The evidence I was seeing was strong enough that it warranted a study of its own," Reed said.

Comparing 14 pairs of parks and preserves

For her study, which will be published in the September 2008 issue of the journal Conservation Letters but is now available online, Reed chose 14 parks in Marin, Sonoma and Napa counties and paired them with 14 nearby preserves with no public access. Each paired park and preserve had to have similar characteristics, such as size and amount of nearby development. The 14 parks include Jack London and Annadel state parks and Shiloh Ranch and Spring Lake regional parks in Sonoma County.

Historically, people have tended to view recreation and conservation efforts as tightly linked, especially when it comes to land management. Parks aim to both protect natural resources and allow visitors to enjoy them. But if this enjoyment is actually detrimental to conservation, as Reed's findings suggest, park agencies may have to change how they think about preservation, the researchers said. Reed feels that, in some cases, it may be necessary to create separate sites for conservation and recreation. That could mean separate areas within large parks or designating small parks, such as the ones Reed surveyed, as either for conservation or recreation,

"People used to think, 'Well, just keep everyone on the trail.' Before this study, that would have been a reasonable assumption," Merenlender said. "But now that we're showing this larger scale effect, we're going to have to shift our working paradigm on how we address land management."

To look at carnivore populations, Reed walked one to two miles in each park or preserve, picking up and bagging every carnivore dropping she saw. Because it's difficult to identify droppings visually, she used genetic analyses to determine each scat's owner.

Reed was surprised to find that coyotes and bobcats were avoiding parks with public access entirely, not just their trails. The parks she visited are small enough that the animals can't find a peaceful spot, Reed said.

Carnivores seeking calm?

Reed thinks the carnivores are leaving the parks for calmer neighboring areas. Her study didn't address the reason for their flight, but she thinks it likely that the mere presence of humans disturbs the animals. The noise of humans traipsing and chatting through parks, our smell or just the sight of us could frighten animals away from their homes, Reed said.

Between urban sprawl, agriculture and outdoor enthusiasts, coyotes, bobcats and foxes may be hard pressed to find undisturbed areas. Outdoor recreation is on the rise around the world, especially in natural areas surrounding large urban centers, such as in the San Francisco Bay Area. For example, the number of Americans day hikers jumped nearly 800 percent between 1960 and 2000, according to national surveys.

These extra hikers, bird-watchers and mountain bikers put pressure on park agencies to open government land and private preserves for public access. "This level of recreational activities in parks is just one of the many ways that the growing human population is squeezing the habitat for these more sensitive species," Reed said.

Reed said her findings affected her on a personal level, because she enjoys hiking and other outdoor activities. "For many of us, as conservation biologists, as environmentalists, this is a pretty uncomfortable result," she said.

The National Science Foundation, Sigma Xi, the Phi Beta Kappa Society, the Budweiser Conservation Scholarship Program and the Robert and Patricia Switzer Foundation provided funding for this study.

Parks included in the study (and their location by county)

Jack London State Historic Park, Sonoma
Annadel State Park, Sonoma
Spring Lake Regional Park, Sonoma
Shiloh Ranch Regional Park, Sonoma
Sonoma Valley Regional Park, Sonoma
Hood Mountain Regional Park, Sonoma
Crane Creek Regional Park, Sonoma
Ragle Ranch Regional Park, Sonoma
Foothill Regional Park, Sonoma
Loma Alta Open Space Preserve, Marin
Terra Linda/Sleepy Hollow Divide Open Space Preserve, Marin
Indian Valley Open Space Preserve, Marin
Westwood Hills Park, City of Napa
Skyline Wilderness Park, Napa

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Blood-Related Genetic Mechanisms Found Important in Parkinson's Disease

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 22 Jul 2008 02:23:25 +0000

For Immediate Release

Blood-Related Genetic Mechanisms Found Important in Parkinson's Disease

July 22, 2008

What does the genetics of blood cells have to do with brain cells related to Parkinson's disease? From an unusual collaboration of neurologists and a pharmacologist comes the surprising answer: Genetic mechanisms at play in blood cells also control a gene and protein that cause Parkinson's disease.

The finding, by scientists from the University of Wisconsin-Madison School of Medicine and Public Health (SMPH), Harvard University-affiliated Brigham and Women's Hospital, and the University of Ottawa, may lead to new treatments for the neurological disorder that affects as many as 1.5 million Americans.

The study is published in the Proceedings of the National Academy of Sciences Online Early Edition this week (July 21-25).

Patients with Parkinson's disease (PD) have elevated levels of the protein called alpha-synuclein in their brains. As the protein clumps, or aggregates, the resulting toxicity causes the death of neurons that produce the brain chemical dopamine. Consequently, nerves and muscles that control movement and coordination are destroyed.

The researchers discovered that the activity of three genes that control the synthesis of heme, the major component of hemoglobin that allows red blood cells to carry oxygen, precisely matched the activity of the alpha-synuclein gene, suggesting a common switch controlling both.

The scientists then found that a protein called GATA-1, which turns on the blood-related genes, was also a major switch for alpha-synuclein expression, and that it induced a significant increase in alpha-synuclein protein. Finally, they demonstrated that a related protein - GATA-2 - was expressed in PD-vulnerable brain cells and directly controlled alpha-synuclein production.

"Very little was known previously about what turns on alpha-synuclein in brain cells and causes variations in its expression," says Emery Bresnick, a UW-Madison professor of pharmacology who is an expert on GATA factors and their functions in blood. "Understanding how GATA factors work in the brain may provide fundamental insights into the biology of Parkinson's disease."

The new knowledge also may allow scientists to design therapies that keep alpha-synuclein levels within the normal range.

"Simply lowering alpha-synuclein levels by 40 percent may be enough to treat some forms of Parkinson's disease," says Clemens Scherzer of Harvard. "So far, researchers have focused on ways to get rid of too much 'bad' alpha-synuclein in Parkinson patients' brains. Now we will be able to tackle the problem from the production site, and search for new therapies that lower alpha-synuclein production up front."

Scherzer and Michael Schlossmacher, now at Ottawa, had independently analyzed the blood of PD patients and controls in a search for genes that were active in the disease. They both were surprised to notice large amounts of alpha-synuclein in the blood. To understand what it was doing there, Scherzer's group used gene chip data to see whether any of the thousands of genes active in blood were linked to alpha-synuclein. They found a gene expression pattern composed of alpha-synuclein and the heme genes, one of which Bresnick had previously shown to be a direct GATA-1 target gene.

The neurologists contacted Bresnick. The UW-Madison group rapidly determined that GATA-1 directly activated the alpha-synuclein gene, and that finding led the collaborators to discover that GATA-2 is expressed in regions of the brain that are relevant to PD.

"We all were excited because we realized that GATA-2 was active in the relevant brain regions, and so there could be a connection," says Bresnick. Together the researchers set out to examine whether common mechanisms activated alpha-synuclein transcription in both the blood and nerve cells.

The studies showed that GATA-1 and GATA-2 proteins find the alpha-synuclein gene, stick to it and then directly control it.

"This is not an indirect pathway; it is direct regulation of the gene," says Bresnick. "This directness provides the simplest scenario for creating a therapeutic strategy."

Bresnick, Schlossmacher and Scherzer are working with geneticists to see if possible abnormalities in the GATA-2 gene may exist in PD patients, stimulating more production of alpha-syinuclein.

"The discovery of the link between GATA proteins and the alpha-synuclein gene is like finding a long-sought-after molecular switch," says Schlossmacher. "We were very fortunate to find in Emery Bresnick's team the ideal partner in this endeavor."

The family of GATA factors consists of six members, and some of them, beyond GATA-2, may also be influencing alpha-synuclein expression in the brain, adds Schlossmacher.

"Identifying these would further add to the complexity of regulating the production of the 'bad player' in Parkinson's disease," he says.

Says Bresnick, "The $10 million question will be, 'Does deregulation of the GATA mechanism in humans lead to alpha-synuclein overproduction and Parkinson's disease?'"

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Scientists Define 21 New Genes Associated with Crohn's Disease

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 22 Jul 2008 01:09:42 +0000

For Immediate Release

Scientists Define 21 New Genes Associated with Crohn's Disease

Tuesday, July 22, 2008

Findings Bring Researchers Closer to Novel Treatments

A consortium of researchers from the United States, Canada, and Europe has identified 21 new genes for Crohn's disease, a chronic disease of the large and small intestines. This discovery, funded in part by the National Institutes of Health (NIH), brings the total number of known genes associated with Crohn's disease to more than 30 and advances understanding of causes and potential avenues to develop new treatments.

The results are reported in the advance online edition of Nature Genetics on June 29. Additional funding for the work was provided by British, Belgian, and French governmental agencies and private foundations.

As a result of the genome-wide scan, the 21 new genes strongly associated with Crohn's were identified, including several functioning in biochemical pathways promoting inflammation, and others whose functions are still unknown. Although the biochemical functions of these variants and how they trigger inflammation in the intestines requires further study, they all represent potential targets for the development of new medications.

"The discovery of 21 new genes for Crohn's disease highlights the importance of large genome-wide studies in determining genes responsible for some of the most common, intractable diseases that plague millions, world-wide,"said Stephen P. James, M.D., director of the Division of Digestive Diseases and Nutrition at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). "NIH will continue to support this and other genetic studies, and we are excited by the prospect of what the next series of studies may uncover."

According to lead author Mark Daly, M.D., assistant professor of medicine at Harvard Medical School, performing the meta-analysis on the three datasets provided the statistical credibility to solidify the association of these genes to Crohn's, and spotlights other genes, that until now, were not implicated with Crohn's. "Exploring the functions of these proteins may offer new targets for treatment for Crohn's"he added.

Crohn's disease is a chronic form of inflammatory bowel disease (IBD) that usually affects the lower part of the small intestine or the large intestine (colon). The most common symptoms of Crohn's are stomach pain and diarrhea. The disease tends to run in families and is more often diagnosed in people between the ages of 20 and 30. People of Jewish heritage, particularly Ashkenazi Jews, have an increased risk of developing Crohn's disease.

To confirm the findings, the researchers repeated the study in 3,664 additional people with Crohn's, unaffected family members and unaffected individuals from the general population. "There is no doubt that the analyses worked correctly and the new genes are truly associated with the disease,"said Daly.

The study, co-funded by NIDDK, was conducted by researchers from the NIDDK IBD Genetics Consortium, the Wellcome (UK) Trust Case Control Consortium and the Belgian-French IBD Genetics Consortium.

Researchers suspect that the 32 gene variants constitute only a small portion of the genes that affect Crohn's disease. To search for more genes and unravel how these genes cause Crohn's, researchers will need larger sample sizes. "Larger samples will also allow the investigators to figure out how particular combinations of genes influence disease risk, age of onset, disease severity, and response to treatment,"noted Robert W. Karp, Ph.D., project scientist for NIDDK's IBD Genetics Consortium in the Division of Digestive Diseases and Nutrition.

Learn more about Crohn's disease at http://digestive.niddk.nih.gov/ddiseases/pubs/crohns/index.htm.

Permalink: http://www.sflorg.com/comm_center/medical/p479_23.html

Time Stamp: 7/22/2008 at 12:57:49 AM UTC

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Heartworm could be more prevalent in dogs, cats this year

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 22 Jul 2008 00:19:21 +0000

For Immediate Release

Heartworm could be more prevalent in dogs, cats this year

July 21, 2008

A mosquito population explosion caused by recent flooding in parts of Indiana is a good reason for dogs and cats to be on heartworm medications this summer.

Steve Thompson of Purdue University's School of Veterinary Medicine says mosquitoes are a potential danger to dogs, cats and ferrets because they are susceptible to heartworm infection. Heartworm can be fatal if it is untreated.

Given heavy rainfall throughout the state in recent months, mosquito breeding is high, and could lead to more heartworm cases this year.

"The mosquito population burst we've had in the past few weeks has made it difficult," says Thompson. "I've noticed from walking my own dog that there is a blitzkrieg of mosquitoes out there this summer."

Dogs and cats that have not been tested in the last six months for heartworm should have one, he says. Dogs should have a blood test annually to detect infections early if they have heartworms.

"The good thing about heartworm prevention is that it literally works 45 days backwards. With any mosquito bite a cat or dog received during the past month, or even longer, the young worm can be killed in the skin before reaching the heart," Thompson says.

Heartworm preventive medication can be administered orally, by a liquid treatment applied to the back of a pet's neck, or by a longer acting injection, Thompson says.

In dogs, heartworms more easily complete their whole life cycle and make it to the heart, compared to cats, Thompson says. Heartworm also progresses differently in dogs and cats. In dogs, heartworm can be fatal when the worm clogs the heart, causing pulmonary hypertension and eventually heart failure. In cats, heartworm can cause sudden lung problems that asthma-like coughing as larvae migrate through the lungs to the heart. Cats can appear healthy minutes before one of the coughing attacks.

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Engineers Prove Graphene is the Strongest Material

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Tue, 22 Jul 2008 00:03:40 +0000

For Immediate Release

Engineers Prove Graphene is the Strongest Material

Monday, July 21, 2008

Research scientists at Columbia University's Fu Foundation School of Engineering and Applied Science have achieved a breakthrough by proving that the carbon material graphene is the strongest material ever measured.

Graphene holds great promise for the development of nano-scale devices and equipment. It consists of a single layer of graphite atoms arranged in a hexagonal lattice, similar to a honeycomb. As a two-dimensional material, every atom is exposed to the surface. It forms the basis of graphite fibers used in tennis rackets and other durable products. When rolled, very useful tiny tubes called nanotubes can be fabricated.

Until now, graphene's estimated strength, elasticity and breaking point were based on complex computer modeling theories. Laboratory tests had been stymied because of two major experimental challenges: the complexity in mechanically grasping graphene specimens to measure their elongation under force, and the difficulty of making specimens small enough to be free of imperfections.

"Our team sidestepped the size issue by creating samples small enough to be defect-free," said Columbia Professor Jeffrey Kysar.

The studies were conducted by postdoctoral researcher Changgu Lee and graduate student Xiaoding Wei, in the research groups of mechanical engineering professors Kysar and James Hone. The findings are published in the latest issue of Science.

"Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel," Hone said. "It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap."

The team culled microscopic graphene samples, in which every single atom is on the surface, from larger graphite crystals. These newly created, two-dimensional samples were then placed over small circular holes etched in silicon to create miniature circular films only one atom thick. The graphene adhered to the silicon because of the attraction between their atoms.

The scientists tested the strength of the films by pushing on their centers with a diamond-tipped atomic force microscope with a radius of 20 billionths of a meter. The absence of flaws in the samples, each about one micron in diameter (one percent of the width of a human hair), enabled the scientists to test both elasticity and breaking point properties. The scientists collected more than 67 test values on 23 separate films.

"Until now, there's been no definitive set of experiments that people can use to validate or invalidate the computer simulations that model the mechanical properties of materials at strains literally up to the breaking point, " said Kysar. "It's important because this is a fundamental parameter for all types of materials.

"The Air Force wants to introduce new materials within a five-year cycle, versus 20 years now, so being able to predict the mechanical behavior of how a new material will fail under the most extreme circumstances will make it much less expensive and less time consuming to develop, and with better materials for everyday life."

"Though the strength of any practical material is still limited by many types of defects, the research can lead to a better understanding of the behavior of materials at extreme conditions, such as [those that] exist near the tip of a crack," said Hone. "This can in turn lead to far more robust materials, ones more resistant to oxidation and fatigue. Achieving a better understanding of how materials fail allows us to design and create newer, safer materials, and ultimately to build a safer, more efficient environment for us."

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'No Organics' Zone Around Pinwheel Galaxy

SFL ORG. Educational News Network / Scientific Frontline admin@sflorg.com — Mon, 21 Jul 2008 20:54:35 +0000

For Immediate Release

'No Organics' Zone Around Pinwheel Galaxy

Monday, July 21, 2008

The Pinwheel galaxy is gussied up in infrared light in a new picture from NASA's Spitzer Space Telescope.

The fluffy-looking galaxy, officially named Messier 101, is dominated by a mishmash of spiral arms. In Spitzer's new view, in which infrared light is color coded, the galaxy sports a swirling blue center and a unique, coral-red outer ring.

A new paper appearing July 20 in the Astrophysical Journal explains why this outer ring stands out. According to the authors, the red color highlights a zone where organic molecules called polycyclic aromatic hydrocarbons, which are present throughout most of the galaxy, suddenly disappear.

Polycyclic aromatic hydrocarbons are dusty, carbon-containing molecules found in star nurseries, and on Earth in barbeque pits, exhaust pipes and anywhere combustion reactions take place. Scientists believe this space dust has the potential to be converted into the stuff of life.

"If you were going look for life in Messier 101, you would not want to look at its edges," said Karl Gordon of the Space Telescope Science Institute in Baltimore, Md. "The organics can't survive in these regions, most likely because of high amounts of harsh radiation."

The Pinwheel galaxy is located about 27 million light-years away in the constellation Ursa Major. It has one of the highest known gradients of metals (elements heavier than helium) of all nearby galaxies in our universe. In other words, its concentrations of metals are highest at its center, and decline rapidly with distance from the center. This is because stars, which produce metals, are squeezed more tightly into the galaxy's central quarters.

Gordon and his team used Spitzer to learn about the galaxy's gradient of polycyclic aromatic hydrocarbons. The astronomers found that, like the metals, the polycyclic aromatic hydrocarbons decrease in concentration toward the outer portion of the galaxy. But, unlike the metals, these organic molecules quickly drop off and are no longer detected at the very outer rim.

"There's a threshold at the rim of this galaxy, where the organic material is getting destroyed," said Gordon.

The findings also provide a better understanding of the conditions under which the very first stars and galaxies arose. In the early universe, there were not a lot of metals or polycyclic aromatic hydrocarbons around. The outskirt of the Pinwheel galaxy therefore serves as a close-up example of what the environment might look like in a distant galaxy.

In this image, infrared light with a wavelength of 3.6 microns is colored blue; 8-micron light is green; and 24-micron light is red. All three of Spitzer instruments were used in the study: the infrared array camera, the multiband imaging photometer and the infrared spectrograph.

Other authors of the paper include Charles Engelbracht, George Rieke, Karl A. Misselt, J.D. Smith and Robert Kennicutt, Jr. of the University of Arizona, Tucson. Smith is also associated with the University of Toledo, Ohio, and Kennicutt is also associated with the University of Cambridge, England.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Jim Houck of Cornell. The multiband imaging photometer for Spitzer was built by Ball Aerospace Corporation, Boulder, Colo., and the University of Arizona, Tucson. Its principal investigator is George Rieke of the University of Arizona.

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