ALL ABOUT SCIENCE - News & Press (所有關於科學的新聞和)

Physics :: Using Life's Building Blocks To Control Nanoparticle...

Author: admin
Subject: Using Life's Building Blocks To Control Nanoparticle...
Posted: Mon 27/Aug/2007 7:18 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070822093124.htm

Science Daily � Using DNA, the molecule that carries life's genetic instructions, researchers at the U.S. Department of Energy's Brookhaven National Laboratory are studying how to control both the speed of nanoparticle assembly and the structure of its resulting nanoclusters.
Learning how to control and tailor the assembly of nanoparticles, which have dimensions on the order of billionths of a meter, could potentially lead to applications ranging from more efficient energy generation and data storage to cell-targeted systems for drug delivery.

Mathew Maye is a chemist in Brookhaven's newly opened Center for Functional Nanomaterials. "We can synthesize nanoparticles with very well controlled optical, catalytic, and magnetic properties," Maye said. "They are usually free-flowing in solution, but for use in a functional device, they have to be organized in three dimensions, or on surfaces, in a well-controlled manner. That's where self assembly comes into play. We want the particles to do the work themselves."

Using optical measurements, transmission electron microscopy, and x-ray scattering at Brookhaven's National Synchrotron Light Source, Maye and his colleagues have shown how to control the self assembly of gold nanoparticles with the assistance of various types of DNA. Their technique takes advantage of this molecule's natural tendency to pair up components called bases, known by the code letters A, T, G and C. The synthetic DNA used in the laboratory is capped onto individual gold nanoparticles and customized to recognize and bind to complementary DNA located on other particles. This process forms clusters, or aggregates, which contain multiple particles.

The research group previously used rigid, double-stranded DNA to speed up and slow down the speed of nanoparticle assembly. Most recently, they also perfected a method for regulating the size of the resulting particle clusters by incorporating multiple types of DNA strands.

On August 22, 2007 Maye will discuss how these two methods provide researchers with precise control of nanoparticle assembly at the 234th National Meeting of the American Chemical Society.

"Self-assembly is really a frontier of nanoscience," Maye said. "Learning how to take a solution of nanomaterials and end up with a functional device is going to be a great achievement."

Note: This story has been adapted from a news release issued by DOE/Brookhaven National Laboratory.
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"We can synthesize nanoparticles with very well controlled optical, catalytic, and magnetic properties," says Mathew Maye, a chemist in Brookhaven's newly opened Center for Functional Nanomaterials. (Credit: Image courtesy of DOE/Brookhaven National Laboratory)

Fausto Intilla's web site: www.oloscience.com
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Fausto Intilla
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Astronomy & Cosmology :: Jupiter: Friend Or Foe?

Author: admin
Subject: Jupiter: Friend Or Foe?
Posted: Sun 26/Aug/2007 12:15 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070824133636.htm

Science Daily � The traditional belief that Jupiter acts as a celestial shield, deflecting asteroids and comets away from the inner Solar System, has been challenged by the first in a series of studies evaluating the impact risk to the Earth posed by different groups of object.
On Friday 24th August at the European Planetary Science Congress in Potsdam, Dr Jonathan Horner presented a study of the impact hazard posed to Earth by the Centaurs, the parent population of the Jupiter Family of comets (JFCs). The results show that the presence of a Jupiter-like planet in the Solar System does not necessarily lead to a lower impact rate at the Earth.
Dr Horner, from the UK's Open University (OU), said, "The idea that a Jupiter-like planet plays an important role in lessening the impact risk on potentially habitable planets is a common belief but there has only really been one study done on this in the past, which looked at the hazard due to the Long Period Comets. We are carrying out an ongoing series of studies of the impact risks in planetary systems, starting off by looking at our own Solar System, since we know the most about it!"

The team at the OU developed a computer model that could track the paths of 100,000 Centaurs around the Solar System over 10 million years. The simulation was run five times: once with Jupiter at its current mass, once without a Jupiter, and then with planets of three-quarters, a half and a quarter the mass of Jupiter (for comparison, Saturn is about a third of the mass of Jupiter). The team found that the impact rate in a Solar System with a planet like our Jupiter is about comparable to the case where there is no Jupiter at all. However, when the mass of Jupiter was between these two extremes, the Earth suffered an increased number of impacts from the JFCs.
Dr Horner said, "We've found that if a planet about the mass of Saturn or a bit larger occupied Jupiter's place, then the number of impacts on Earth would increase. However if nothing was there at all, there wouldn't be any difference from our current impact rate. Rather than it being a clear cut case that Jupiter acts as a shield, it seems that Jupiter almost gives with one hand and takes away with the other!"
The study shows that if there is no giant planet present, the JFCs will not be diverted onto Earth-crossing orbits, so the impact rate at the Earth is low. A Saturn-mass planet would have the gravitational pull to inject objects onto Earth-crossing orbits, but would not be massive enough to easily eject objects from the Solar System. This means that there would be more objects on Earth-crossing orbits at any given time, and therefore more impacts.
However, a planet with Jupiter's vast mass can give objects the gravitational boost to eject them from the Solar System. Therefore, if Jupiter deflects JFCs to an Earth-crossing orbit, it may well later sweep them right out of the Solar System and off the collision course with the Earth.
The group is now assessing the impact risk posed to the Earth by the Asteroids and will go on to study the Long Period Comets, before examining the role of the position of Jupiter within our system.

Jupiter family of comets:
The Jupiter Family of Comets (JFCs) are short period comets with an orbital period of less than 20 years. Their orbits are controlled by Jupiter and they are believed to originate from the Kuiper Belt, a vast population of small icy bodies that orbit just beyond Neptune. Famous JFCs include Comet 81P/Wild 2, which was encountered by the Stardust spacecraft in January 2004 and Comet Shoemaker Levy-9, which broke up and collided with Jupiter in July 1994.
Note: This story has been adapted from a news release issued by European Planetology Network.
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Heavy bombardment (Credit: Copyright Julian Baum)

Fausto Intilla's web site: www.oloscience.com
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Fausto Intilla
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Astronomy & Cosmology :: Polluted Dead Star Indicates Planets Like Earth May Have...

Author: admin
Subject: Polluted Dead Star Indicates Planets Like Earth May Have...
Posted: Sat 18/Aug/2007 3:38 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070816214820.htm

Polluted Dead Star Indicates Planets Like Earth May Have Formed Around Other Stars.
Science Daily � The chemical fingerprint of a burned-out star indicates that Earth-like planets may not be rare in the universe and could give clues to what our solar system will look like when our sun dies and becomes a white dwarf star some five billion years from now.
Astronomers from UCLA report that a white dwarf star known as GD 362, which is surrounded by dusty rings similar to those of Saturn, has been contaminated by a large asteroid that left more than a dozen observable chemical elements in the white dwarf's atmosphere. Such an observation is unprecedented in astronomy. Was there some kind of violent interaction between the star and the asteroid?

The UCLA astronomers think that after about a billion years orbiting the white dwarf as part of an ancient planetary system, an asteroid got close enough to the star to be torn apart by its very strong gravitational force field. An Earth-sized but exceedingly dense white dwarf is the standard end state for most stars. This particular white dwarf, which is under investigation by the W.M. Keck Observatory in Hawaii, is located in the constellation Hercules, approximately 150 light-years, or 1,000 trillion miles, from Earth.

The asteroid broke apart into dust particles that orbited the white dwarf and over time "polluted the white dwarf's atmosphere," said Benjamin Zuckerman, UCLA professor of physics and astronomy and lead author of the research, which has been accepted for publication in an upcoming issue of the Astrophysical Journal.

The astronomers note that the spectroscopic observations they are reporting constitute the first detailed assessment of the elemental composition of an object in an extrasolar planetary system.

"The relative abundance of the elements in the white dwarf's atmosphere, polluted by the asteroid, appears similar to those in our Earth-Moon system," Zuckerman said.

"What we have here is a composition of the white dwarf that is fairly similar to that of the inner planets of our solar system," said Michael Jura, UCLA professor of physics and astronomy and co-author of the research. "Are there other terrestrial planets like Earth in other solar systems? This white dwarf's fingerprint is a significant advance in demonstrating that something like terrestrial planet formation occurred around this other star and probably occurred around other stars as well, because it suggests the Earth's composition is not unique.

"The asteroid that is being shredded is very iron-rich and abundant in calcium and other elements, and low in carbon, like a sturdy rock," Jura added.

The research implies that the forces that made the Earth and our inner solar system seem to have occurred in this system as well, and probably around other white dwarfs too, Jura said.

Zuckerman said the research result does not rule out the possibility that two planets in this ancient planetary system collided and the orbiting dust and detected elements are from a piece of one of the colliding planets rather than from a more conventional asteroid.

"Something dramatic and violent probably happened," he said.

What knocked the asteroid out of its original orbit? It probably was deflected by the gravitational field of a large planet, Zuckerman said.

Our own planetary system looks very stable, Zuckerman said, but billions of years from now, when the sun starts to expand in size and lose mass rapidly, the planets and asteroids will spiral away, and the planets closest to the sun, like Mercury and Venus, will be engulfed by the sun and destroyed.

"But other planets, probably including the Earth and the asteroid belt between Mars and Jupiter will spiral out, and their orbits then will make our stable system much less stable," he said.

A third UCLA author on the paper, physics and astronomy associate professor Brad Hansen, said, "In our solar system, objects rich in iron formed closer to the sun than the objects rich in carbon and ice, which formed farther away, where it is colder. This research tells us about the origin of the asteroid, its temperature when it formed and its chemistry � conditions similar to the Earth's."

The group of astronomers, which also includes of UCLA graduate student Carl Melis and Detlev Koester at Germany's University of Kiel, detected 17 elements in the atmosphere of the white dwarf that probably came from a large asteroid; the asteroid may have once been part of a larger body, perhaps like one of the inner planets of our solar system. Many of the elements have never before been detected in the atmosphere of a white dwarf, including the rare elements strontium and scandium.

The gravitational field of the white dwarf is so strong that all elements heavier than the lightest elements � hydrogen and helium � quickly sink into the white dwarf's interior, Hansen said.

The asteroid likely broke up more than 100,000 years ago, and perhaps as long as a million years ago, the astronomers said. The star became a very hot white dwarf approximately 1 billion years ago and since then has been steadily cooling off.

Unlike GD 362, most white dwarfs are pristine in their composition.

"You wouldn't notice another skyscraper in New York, but the same skyscraper in Nebraska would stick out like a sore thumb," Hansen said. "That's the case here. A little change in the atmosphere of a white dwarf is very obvious."

The astronomers used the HIRES spectrometer on the Keck I Telescope to take optical spectra of the white dwarf, spanning the ultraviolet to the full visible range of light. Each element can be identified by its own characteristic spectrum.

The researchers said they find it quite remarkable that even at a distance of 1,000 trillion miles, the Keck HIRES measurements enable them to determine minute details of the bulk composition of a relatively tiny object � as astronomical sizes go � like an asteroid. Currently, no other known observational technique exists that allows for such compositional information to be obtained.

The remains of a white dwarf cool slowly over many billions of years as the dying ember makes its slow journey into oblivion.

NASA funded the research.

Note: This story has been adapted from a news release issued by University of California, Los Angeles.
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Artist's visualization of a dust disk around the white dwarf GD 362. This new research implies that the forces that made the Earth and our inner solar system seem to have occurred in this system as well, and probably around other white dwarfs too. (Credit: Gemini Observatory Illustration by Jon Lomberg)

Fausto Intilla web site: www.oloscience.com
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Fausto Intilla
(divulgatore scientifico)
www.oloscience.com

Electronics :: Nanoscale Blasting Adjusts Resistance In Magnetic Sensors

Author: admin
Subject: Nanoscale Blasting Adjusts Resistance In Magnetic Sensors
Posted: Fri 17/Aug/2007 11:57 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070816173259.htm

Science Daily � A new process for adjusting the resistance of semiconductor devices by carpeting a small area of the device with tiny pits, like a yard dug up by demented terriers, may be the key to a new class of magnetic sensors, enabling new, ultra-dense data storage devices.
The technique demonstrated by researchers at the National Institute of Standards and Technology (NIST)* allows engineers to tailor the electrical resistance of individual layers in a device without changing any other part of the processing or design.

The tiny magnetic sensors in modern disk drives are a sandwich of two magnetic layers separated by a thin buffer layer. The layer closest to the disk surface is designed to switch its magnetic polarity quickly in response to the direction of the magnetic "bit" recorded on the disk under it. The sensor works by measuring the electrical resistance across the magnetic layers, which changes depending on whether the two layers have matching polarities.

As manufacturers strive to make disk storage devices smaller and more densely packed with data, the sensors need to shrink as well, but current designs are starting to hit the wall. To meet the size constraints, prototype sensors measure sensor resistance perpendicular to the thin layers, but depending on the buffer material in the sensor, two different types of sensors can be made.

Giant magneto-resistance (GMR) sensors use a low-resistance metal buffer layer and are fast, but plagued by very low, difficult to detect, signals. On the other hand, magnetic tunnel junction (MTJ) sensors use a relatively high-resistance insulating buffer that delivers a strong signal, but has a slower response time, too slow to keep up with a very high-speed, high-capacity drive.

What's needed, says NIST physicist Josh Pomeroy, is a compromise. "Our approach is to combine these at the nanometer scale. We start out with a magnetic tunnel junction--an insulating buffer--and then, by using highly charged ions, sort of blow out little craters in the buffer layer so that when we grow the rest of the sensor on top, these craters will act like little GMR sensors, while the rest will act like an MTJ sensor." The combined signal of the two effects, the researchers argue, should be superior to either alone.

The NIST team has demonstrated the first step--the controlled pockmarking of an insulating layer in a multi-layer structure to adjust its total resistance. The team uses small numbers of highly charged xenon ions that each have enormous potential energies--and can blast out surface pits without damaging the substrate. With each ion carrying more than 50 thousand electron volts of potential energy, only one impact is needed to create a pit--multiple hits in the same location are not necessary.

Controlling the number of ions provides fine control over the number of pits etched, and hence the resistance of the layer--currently demonstrated over a range of three orders of magnitude. NIST researchers now are working to incorporate these modified layers into working magnetic sensors.

The new technique alters only a single step in the fabrication process--an important consideration for future scale-up--and can be applied to any device where it's desirable to fine-tune the resistance of individual layers. NIST has a provisional patent on the work, number 60,905,125.

* J.M. Pomeroy, H. Grube, A.C. Perrella and J.D. Gillaspy. Selectable resistance-area product by dilute highly charged ion irradiation. Appl. Phys. Lett. 91, 073506 (2007).

Note: This story has been adapted from a news release issued by National Institute of Standards and Technology.
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Cartoon illustrates new NIST technique for selectively modifying resistance of a semiconductor device layer. (Top) First layerin this case a composite of copper and cobaltand an insulating buffer layer of aluminum oxide is deposited. Buffer is about one nanometer thick. (Middle) Highly charged xenon +44 ions strike the buffer layer, digging nanoscale pits. (Bottom) Top conducting layer of cobalt and copper is deposited. Pits reduce the electrical resistance of the layers and may function as nanoscale GMR sensors embedded in a MTJ sensor. (Credit: NIST)

Fausto Intilla's web site: www.oloscience.com
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Astronomy & Cosmology :: Dark Matter Mystery Deepens In Cosmic 'Train Wreck'

Author: admin
Subject: Dark Matter Mystery Deepens In Cosmic 'Train Wreck'
Posted: Fri 17/Aug/2007 11:46 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070816121055.htm

Science Daily � Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior.
"These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even reexamine the nature of dark matter itself."

There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects.

Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas.

A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

"It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves."

In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies.

"The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't""

In the Bullet Cluster, known as 1E 0657-56, the hot gas is slowed down during the collision but the galaxies and dark matter appear to continue on unimpeded. In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas.

Mahdavi and his colleagues have two possible explanations for their findings, both of which are uncomfortable for prevailing theories. The first option is that the galaxies were separated from the dark matter through a complex set of gravitational "slingshots." This explanation is problematic because computer simulations have not been able to produce slingshots that are nearly powerful enough to cause such a separation.

The second option is that dark matter is affected not only by gravity, but also by an as-yet-unknown interaction between dark matter particles. This exciting alternative would require new physics and could be difficult to reconcile with observations of other galaxies and galaxy clusters, such as the aforementioned Bullet Cluster.

In order to confirm and fully untangle the evidence for the Abell 520 dark matter core, the researchers have secured time for new data from Chandra plus the Hubble Space Telescope. With the additional observations, the team hopes to resolve the mystery surrounding this system.

These results are scheduled to appear in the October 20th issue of The Astrophysical Journal. Other members of the research team included David Balam (University of Victoria) and Peter Capak (California Institute of Technology).

Note: This story has been adapted from a news release issued by Chandra X-ray Center.
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This multi-wavelength image shows the chaotic aftermath of the collision of at least two galaxy clusters, some of the most massive objects in the universe. X-rays from Chandra (red) show the hot gas the envelopes the clusters. The individual galaxies appear in visible-light observations (yellow and orange), which also reveal the presence of dark matter (blue) by the subtle distortions of the distant objects. The behavior of the dark matter with respect to the galaxies and hot gas in Abell 520 is very unusual. These data can be explained by changes to the current understanding of dark matter or how galaxy clusters interact when merging. (Credit: X-ray: NASA/CXC/UVic./A. Mahdavi et al. optical/lensing: CFHT/UVic./H. Hoekstra et al.)

Fausto Intilla's web site: www.oloscience.com
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Fausto Intilla
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Behavioral & Social Sciences :: Toddlers Are Capable Of Introspection

Author: admin
Subject: Toddlers Are Capable Of Introspection
Posted: Fri 17/Aug/2007 11:38 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070815135023.htm

Science Daily � Preschoolers are more introspective than we give them credit for, according to new research by Simona Ghetti, assistant professor of psychology at UC Davis.
Ghetti and her co-investigator, Kristen Lyons, a graduate student in psychology at UC Davis, will present their findings August 17, at the annual meeting of the American Psychological Association in San Francisco.

Scientists have demonstrated that dolphins, monkeys and even rats can engage in some form of "metacognition," or an awareness of their own thought processes. But developmental psychologists have assumed that human children do not develop this capability before about age 5.

Lyons and Ghetti have toppled that assumption by teaching 3- and 4-year-olds to communicate their awareness of their thought processes using pictures rather than words.

"We've shown that even very young children can think about their thinking," Ghetti said. "The reason we haven't appreciated it before now is that the studies that have been used to test for it have been too verbally demanding."

The UC Davis researchers devised a novel method to investigate metacognition in early childhood. They taught their preschool subjects to point to a photo of a confident-looking face when they felt confident they had the right answer to a question, and to a photo of a doubtful-looking child when they were not confident they had the right answer.

The tests showed that young children are aware of their uncertainty in the moment. Even 3-year-olds pointed to the confident face when they correctly identified, for example, a drawing of a monkey that had some features removed to make it harder to recognize. They pointed to the doubtful face if they could not come up with a correct answer.

"Even 3-year-olds are more confident when they're right than when they're wrong," Ghetti said.

How children develop the ability to experience, recognize and understand their thoughts and emotions is a topic of increasing scientific interest, since self-awareness is a prerequisite for the development of a wide range of important human traits, from a conscience to healthy relationships.

Note: This story has been adapted from a news release issued by University of California - Davis.
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The researchers taught 3- and 4-year-olds to communicate their awareness of their thought processes using pictures rather than words, as this mother is doing with her son. (Credit: iStockphoto/Sean Locke)

Fausto Intilla's web site: www.oloscience.com
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Fausto Intilla
(divulgatore scientifico)
www.oloscience.com

Biology :: Gene Mutation Turned West Nile Virus Into Killer Disease...

Author: admin
Subject: Gene Mutation Turned West Nile Virus Into Killer Disease...
Posted: Thu 16/Aug/2007 20:15 (GMT 2)
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Source: http://www.sciencedaily.com/releases/2007/08/070814135646.htm

Gene Mutation Turned West Nile Virus Into Killer Disease Among Crows.
Science Daily � A gene mutation that appears to be responsible for changing relatively mild forms of the West Nile virus into a highly virulent and deadly disease in American crows has been identified by a team of scientists led by a researcher at the University of California, Davis.
Because it is highly susceptible to West Nile virus, the American crow has served as the major sentinel species, playing an important role in alerting scientists and health professionals to the movement of the disease across North America.

"The findings from this study highlight the potential for viruses like West Nile to rapidly adapt to changing environments when introduced to new geographic regions," said Aaron C. Brault, a virologist at the Center for Vectorborne Diseases in the Department of Pathology, Microbiology and Immunology of the UC Davis School of Veterinary Medicine.

"The study also suggests that the genetic mutations that create such adaptive changes may result in viral strains that have unexpected symptoms and patterns of transmission," Brault said.

About West Nile virus

West Nile virus, which is passed back and forth between birds and mosquitoes and transmitted to humans via mosquito bites, was first identified in 1937 in Uganda. Although it was recognized as a cause of severe encephalitis and meningitis (inflammation of the brain and spinal cord, respectively) during a 1957 outbreak in Israel, it has been primarily associated with mild infections accompanied by fevers in humans in Africa and the Middle East.

In 1996, West Nile virus caused an outbreak of encephalitis in Romania, moving on to cause similar outbreaks throughout the next several years in Israel, Tunisia and Russia.

In 1999, the virus was first recognized in North America and has since been reported in humans, birds, horses and mosquitoes in Canada and in all of the contiguous U.S. states. It has become the leading cause of encephalitis from a virus transmitted by arthropods, a group of invertebrates that includes insects, spiders and ticks.

West Nile in birds

A variety of North American bird species, including ring-billed gulls, house finches, crows and black-billed magpies, are extremely susceptible to West Nile virus. In fact, a hallmark of the West Nile virus in North America has been how deadly the virus has been among wild and captive birds. Particularly vulnerable to West Nile virus is the American crow, which is common in urban and suburban areas as well as in all natural habitats except the Southwestern deserts.

Because the American crow is so common and so highly susceptible to West Nile virus, it has served as the sentinel species in North America. Epidemiological studies have found that deaths of American crows due to West Nile virus are associated with higher rates of infection among mosquito populations and clusters of the disease in humans.Although scientists and health professionals have thoroughly described how West Nile virus spreads through both human and animal populations in North America, it has been unclear just how the virus emerged to cause such serious disease in birds, particularly the American crow.

Pinpointing the gene mutation site

To identify how West Nile virus developed into such a deadly disease for birds, the research team looked to the genetic makeup of the virus. West Nile virus is an RNA virus -- its genetic material being composed of RNA, rather than DNA. Although RNA and DNA molecules differ somewhat in structure and function, both play key roles in enabling cells to build the proteins necessary for reproducing and carry out the cells' functions.

The researchers analyzed the evolutionary relationships of the West Nile virus genomes, or entire collections of genes, for 21 different strains of West Nile viruses that had been sampled globally in recent years, including strains from North America. Analysis of genetic patterns indicated a disproportionate rate of change at a particular amino acid within one of the viral genes.

Onto this genome "tree" for the various strains of West Nile virus, they mapped the mutational changes in the same gene region mentioned above. They found that the same amino acid change had occurred three different times and that the resulting virus had been associated with human disease outbreaks.

In order to determine if this mutation was associated with the increased virulence of the West Nile virus in birds and its subsequent ability to spread to humans, the researchers introduced the mutation independently into the low-virulence virus. They also removed that mutation from the highly virulent North American strain.

At that location, the researchers made changes in the amino acids, which they suspected might change a relatively mild West Nile virus strain from Kenya into a much more virulent strain and, conversely, could weaken the more potent New York strain.

Then they inoculated American crows with either a parent virus or one of the newly created recombinant viruses in order to observe the viruses' activity.

As expected, they found that the parent virus from the relatively mild Kenya strain did not become detectable in the crows' bloodstream until two to three days after the birds were infected. However, the new recombinant form of that viral strain quickly became detectable in the crows' bloodstream, and by the third day was present at 10,000 times the concentration of the parent virus from which it was developed, killing nearly all.

The researchers then made the reciprocal amino acid change in the parent virus of the virulent New York strain of West Nile virus, drastically reducing its deadliness in crows. This weakened New York strain was comparable to the relatively mild parent virus from Kenya in terms of detectable levels in the bloodstream and its deadliness among the inoculated crows.

"It appears that the naturally occurring changes in the amino acids at this particular gene site have played an important role in increasing the virulence of West Nile virus in birds before it appeared in North America," Brault said. "Furthermore, these data indicate how much West Nile virus relies on replicating to high levels in birds for efficient transmission of the virus, potentially leading to human disease outbreaks."

The results of the study were reported in the August 12 online issue of the journal Nature Genetics.

Funding for the study was provided by the Centers for Disease Control and Prevention, the National Institutes of Health and the Pacific Southwest Regional Center for Excellence.

Note: This story has been adapted from a news release issued by Univesity of California, Davis.
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Researcher Becky Walther blows on feathers to inspect the skin underneath a crow suspected of having died from West Nile disease. (Credit: UC Davis photo)

Fausto Intilla's web site: www.oloscience.com
_________________
Fausto Intilla
(divulgatore scientifico)
www.oloscience.com

Astronomy & Cosmology :: Speeding Star: Johnny Appleseed Of The Cosmos

Author: admin
Subject: Speeding Star: Johnny Appleseed Of The Cosmos
Posted: Thu 16/Aug/2007 20:07 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070815174450.htm

Science Daily � A new ultraviolet mosaic from NASA's Galaxy Evolution Explorer shows a speeding star that is leaving an enormous trail of "seeds" for new solar systems. The star, named Mira (pronounced my-rah) after the latin word for "wonderful," is shedding material that will be recycled into new stars, planets and possibly even life as it hurls through our galaxy.
Mira appears as a small white dot in the bulb-shaped structure at right, and is moving from left to right in this view. The shed material can be seen in light blue. The dots in the picture are stars and distant galaxies.

The Galaxy Evolution Explorer discovered Mira's strange comet-like tail during part of its routine survey of the entire sky at ultraviolet wavelengths. When astronomers first saw the picture, they were shocked because Mira has been studied for over 400 years yet nothing like this has ever been documented before.

Mira's comet-like tail stretches a startling 13 light-years across the sky. For comparison, the nearest star to our sun, Proxima Centauri, is only about 4 light-years away. Mira's tail also tells a tale of its history � the material making it up has been slowly blown off over time, with the oldest material at the end of the tail having been released about 30,000 years ago.

Mira is a highly evolved, "red giant" star near the end of its life. Technically, it is called an asymptotic giant branch star. It is red in color and bloated; for example, if a red giant were to replace our sun, it would engulf everything out to the orbit of Mars. Our sun will mature into a red giant in about 5 billion years.

Like other red giants, Mira will lose a large fraction of its mass in the form of gas and dust. In fact, Mira ejects the equivalent of the Earth's mass every 10 years. It has released enough material over the past 30,000 years to seed at least 3,000 Earth-sized planets or 9 Jupiter-sized ones.

While most stars travel along together around the disk of our Milky Way, Mira is charging through it. Because Mira is not moving with the "pack," it is moving much faster relative to the ambient gas in our section of the Milky Way. It is zipping along at 130 kilometers per second, or 291,000 miles per hour, relative to this gas.

Mira's breakneck speed together with its outflow of material are responsible for its unique glowing tail. Images from the Galaxy Evolution Explorer show a large build-up of gas, or bow shock, in front of the star, similar to water piling up in front of a speeding boat. Scientists now know that hot gas in this bow shock mixes with the cooler, hydrogen gas being shed from Mira, causing it to heat up as it swirls back into a turbulent wake. As the hydrogen gas loses energy, it fluoresces with ultraviolet light, which the Galaxy Evolution Explorer can detect.

Mira, also known as Mira A, is not alone in its travels through space. It has a distant companion star called Mira B that is thought to be the burnt-out, dead core of a star, called a white dwarf. Mira A and B circle around each other slowly, making one orbit about every 500 years. Astronomers believe that Mira B has no effect on Mira's tail.

Mira is also what's called a pulsating variable star. It dims and brightens by a factor of 1,500 every 332 days, and will become bright enough to see with the naked eye in mid-November 2007. Because it was the first variable star with a regular period ever discovered, other stars of this type are often referred to as "Miras."

Mira is located 350 light-years from Earth in the constellation Cetus, otherwise known as the whale. Coincidentally, Mira and its "whale of a tail" can be found in the tail of the whale constellation.

Note: This story has been adapted from a news release issued by National Aeronautics and Space Administration.
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This mosaic is made up of individual images taken by the far-ultraviolet detector on the Galaxy Evolution Explorer between November 18 and December 15, 2006. (Credit: NASA/JPL-Caltech)

Fausto intilla's web site: www.oloscience.com
_________________
Fausto Intilla
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Astronomy & Cosmology :: Star Light, Star Bright: Duplicating Conditions Of Supernova

Author: admin
Subject: Star Light, Star Bright: Duplicating Conditions Of Supernova
Posted: Thu 16/Aug/2007 7:29 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070814150620.htm

Science Daily � How is matter created? What happens when stars die? Is the universe shrinking, or is it expanding? For decades, scientists have been looking for answers to such "big picture" questions.
For the past few months, members of the department of physics at Florida State University have begun using a groundbreaking new research facility to conduct experiments that may help provide answers to just such questions.

RESOLUT -- short for "REsonator SOLenoid with Upscale Transmission" -- is the name of the facility, which is located within the John D. Fox Superconducting Accelerator Laboratory on the FSU campus. Over the past few months, FSU researchers have begun using RESOLUT to create very rare, extremely short-lived radioactive particles similar to those that form inside exploding stars -- and then using the analytical data produced in the experiments as the basis for hypotheses about the behavior of matter and the physical properties governing the universe.

"We're doing experiments that replicate, in a very controlled manner, the explosions that take place in stars," said Ingo Wiedenhover, an associate professor of physics at FSU who heads up the RESOLUT team. "This helps us understand the nuclear processes that occur in stars, the origin of elements, and how stars explode."

Getting to this point has been an arduous process that began in 2002.

"After five years of proposals, fundraising, designing, building and carefully testing RESOLUT, we are very excited that it has now come online for experiments," said Samuel L. Tabor, a professor of physics at FSU who directs the John D. Fox Superconducting Accelerator Laboratory. "To my knowledge, only one other university in the entire United States has a facility similar to RESOLUT, so our students have a pretty unique opportunity to receive hands-on experience that they can get almost nowhere else."

Weighing some 16 tons and taking up more than 450 square feet of space along a wall inside the accelerator lab, RESOLUT enables researchers to fire a beam of atomic particles through a steel tube at speeds approaching 60 million miles per hour -- roughly one-tenth the speed of light -- and then to observe the nuclear reactions that occur.

"When the beam strikes a target, the collision produces very exotic nuclei that contain properties similar to those occurring in stars and star explosions," Wiedenhover said. "But perhaps RESOLUT's greatest value as a scientific instrument is its function as a mass spectrometer -- a device that allows us to identify and study the short-lived particles created during these miniature explosions."

Wiedenhover currently is overseeing several experiments using RESOLUT that create, for a fraction of a second, a specific type of radioactive nuclei that are found only in a type of exploding star known as a Type Ia supernova.

"Type Ia supernovas result when a certain type of star known as a white dwarf reaches a critical mass and burns through its nuclear fuel so quickly that it suddenly explodes," Wiedenhover said. "What makes these explosions so useful for astrophysicists is that they always release the same amount of energy, so their peak brightness is virtually the same in all instances. This uniform level of brightness makes Type Ia supernovas useful as a 'standard candle' -- a gauge for measuring distances across the universe."

Such standard candles also have helped scientists to determine in recent years that the universe is expanding, not shrinking -- and that the expansion is taking place at an ever-increasing rate.

"Observations of Type Ia supernovas have greatly increased science's understanding of the workings of the universe," Tabor said. "Now, with RESOLUT, we hope to learn even more about these gigantic nuclear explosions -- all from the safety of a lab in a basement on the FSU campus."

Note: This story has been adapted from a news release issued by Florida State University.
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Type Ia supernovas. (Credit: Image courtesy of Florida State University)

Fausto Intilla's web site: www.oloscience.com
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Computer Science :: Engineers Ready A Blueprint For A Nanomechanical Computer

Author: admin
Subject: Engineers Ready A Blueprint For A Nanomechanical Computer
Posted: Wed 15/Aug/2007 21:56 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070814102020.htm

Science Daily � If efforts now under way by a team of University of Wisconsin-Madison engineers pan out, the age of the nanomechanical computer may be at hand.
Instead of relying on solid-state transistors and other electronic components to compute ones and zeroes, such a machine would depend purely on moving parts - gates and pillars and levers and pistons - to create switches, logic gates and memory units, the building blocks of digital computers.

"The aim is to have a new type of device for computing applications," says Robert Blick, a UW-Madison professor of electrical and computer engineering and senior author of a paper in the July 24 New Journal of Physics that outlines a plan for making a computer based on microscopic moving parts.

Conventional devices use electrons that travel in circuits to perform the calculations that drive the functions of computer chips. A nanomechanical computer would also depend on electrons, but instead of the solid state electronic components used in conventional computers to channel them into working circuits, the nanomechanical device would rely on the push and pull of millions of microscopic parts to control the flow of electrons.

Inspiration for the Wisconsin effort resides in the purely mechanical computers of the past. The most famous is the "difference engine" produced by 19th century English mathematician Charles Babbage. Hand-held mechanical calculators, Blick notes, were developed in the 1950s and were sold as recently as the early 1970s.

Computer chips based on nanomechanical parts are not likely to compete with conventional electronic devices, Blick says, but they would have key advantages that could lead to hybrid chips or specialized roles for all-mechanical nanodevices.

For example, nanomechanical chips promise to be more rugged and durable than conventional silicon chips, making them potentially useful for extreme environments such as space, car engines, battlefields and children's toys. What's more, they would require less power to operate and could perform at much higher temperatures - up to 500 degrees Celsius - obviating the need for the energy-eating cooling systems required for electronic, silicon-based computers.

It's estimated that between 15 and 20 percent of total energy use in the United States is devoted to operating and cooling computers. "That's one of our motivations. That's why we have this dream to attack the problem at the root," Blick says.

More energy-efficient chips would also have potential for portable computers, as battery power tends to be the limiting factor for laptops.

Blick's group has already made a working silicon model of a mechanical transistor, the basic switch at the heart of all computers, and is now in the process of trying to align several elements into a working circuit.

"We've tested these single devices and we've shown that a single element works," says Blick. "The next step is to demonstrate memory. We're starting with the basics of information engineering."

The components of a nanomechanical computer, according to Blick, would likely be made of materials other than silicon. Ultra-hard diamond film is one possible material, as it can be chemically treated and is amenable to the methods used to mass-produce integrated circuits.

An important consideration, Blick explains, is developing a system that can achieve industrial-scale production and uses existing industrial lithographic techniques.

"We have some idea of how to mass-fabricate (these devices) in the clean room," Blick says. "We think it might be four years to having a product."

Note: This story has been adapted from a news release issued by University of Wisconsin-Madison.
__________________________________________________________

Fausto Intilla's web site: www.oloscience.com
_________________
Fausto Intilla
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Electronics :: Bendable Batteries: Storing Power In A Piece Of Paper

Author: admin
Subject: Bendable Batteries: Storing Power In A Piece Of Paper
Posted: Wed 15/Aug/2007 21:53 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070814085347.htm

Science Daily � Researchers at Rensselaer Polytechnic Institute have developed a new energy storage device that easily could be mistaken for a simple sheet of black paper.
The nanoengineered battery is lightweight, ultra thin, completely flexible, and geared toward meeting the trickiest design and energy requirements of tomorrow's gadgets, implantable medical equipment, and transportation vehicles.

Along with its ability to function in temperatures up to 300 degrees Fahrenheit and down to 100 below zero, the device is completely integrated and can be printed like paper. The device is also unique in that it can function as both a high-energy battery and a high-power supercapacitor, which are generally separate components in most electrical systems. Another key feature is the capability to use human blood or sweat to help power the battery.

The semblance to paper is no accident: more than 90 percent of the device is made up of cellulose, the same plant cells used in newsprint, loose leaf, lunch bags, and nearly every other type of paper.

Rensselaer researchers infused this paper with aligned carbon nanotubes, which give the device its black color. The nanotubes act as electrodes and allow the storage devices to conduct electricity. The device, engineered to function as both a lithium-ion battery and a supercapacitor, can provide the long, steady power output comparable to a conventional battery, as well as a supercapacitor's quick burst of high energy.

The device can be rolled, twisted, folded, or cut into any number of shapes with no loss of mechanical integrity or efficiency. The paper batteries can also be stacked, like a ream of printer paper, to boost the total power output.

"It's essentially a regular piece of paper, but it's made in a very intelligent way," said paper co-author Robert Linhardt, the Ann and John H. Broadbent Senior Constellation Professor of Biocatalysis and Metabolic Engineering at Rensselaer.

"We're not putting pieces together -- it's a single, integrated device," he said. "The components are molecularly attached to each other: the carbon nanotube print is embedded in the paper, and the electrolyte is soaked into the paper. The end result is a device that looks, feels, and weighs the same as paper."

The creation of this unique nanocomposite paper drew from a diverse pool of disciplines, requiring expertise in materials science, energy storage, and chemistry. Along with Linhardt, authors of the paper include Pulickel M. Ajayan, professor of materials science and engineering, and Omkaram Nalamasu, professor of chemistry with a joint appointment in materials science and engineering. Senior research specialist Victor Pushparaj, along with postdoctoral research associates Shaijumon M. Manikoth, Ashavani Kumar, and Saravanababu Murugesan, were co-authors and lead researchers of the project. Other co-authors include research associate Lijie Ci and Rensselaer Nanotechnology Center Laboratory Manager Robert Vajtai.

The researchers used ionic liquid, essentially a liquid salt, as the battery's electrolyte. It's important to note that ionic liquid contains no water, which means there's nothing in the batteries to freeze or evaporate. "This lack of water allows the paper energy storage devices to withstand extreme temperatures," Kumar said.

Along with use in small handheld electronics, the paper batteries' light weight could make them ideal for use in automobiles, aircraft, and even boats. The paper also could be molded into different shapes, such as a car door, which would enable important new engineering innovations.

"Plus, because of the high paper content and lack of toxic chemicals, it's environmentally safe," Shaijumon said.

Paper is also extremely biocompatible and these new hybrid battery/supercapcitors have potential as power supplies for devices implanted in the body. The team printed paper batteries without adding any electrolytes, and demonstrated that naturally occurring electrolytes in human sweat, blood, and urine can be used to activate the battery device.

"It's a way to power a small device such as a pacemaker without introducing any harsh chemicals -- such as the kind that are typically found in batteries -- into the body," Pushparaj said.

The materials required to create the paper batteries are inexpensive, Murugesan said, but the team has not yet developed a way to inexpensively mass produce the devices. The end goal is to print the paper using a roll-to-roll system similar to how newspapers are printed.

"When we get this technology down, we'll basically have the ability to print batteries and print supercapacitors," Ajayan said. "We see this as a technology that's just right for the current energy market, as well as the electronics industry, which is always looking for smaller, lighter power sources. Our device could make its way into any number of different applications."

The team of researchers has already filed a patent protecting the invention. They are now working on ways to boost the efficiency of the batteries and supercapacitors, and investigating different manufacturing techniques.

"Energy storage is an area that can be addressed by nanomanufacturing technologies and our truly inter-disciplinary collaborative activity that brings together advances and expertise in nanotechnology, room-temperature ionic liquids, and energy storage devices in a creative way to devise novel battery and supercapacitor devices," Nalamasu said.

Details of the project are outlined in the paper "Flexible Energy Storage Devices Based on Nanocomposite Paper" published Aug. 13 in the Proceedings of the National Academy of Sciences.

The paper energy storage device project was supported by the New York State Office of Science, Technology, and Academic Research (NYSTAR), as well as the National Science Foundation (NSF) through the Nanoscale Science and Engineering Center at Rensselaer.

Note: This story has been adapted from a news release issued by Rensselaer Polytechnic Institute.
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A sample of the new nanocomposite paper developed by researchers at Rensselaer Polytechnic Institute. Infused with carbon nanotubes, the paper can be used to create ultra-thin, flexible batteries and energy storage devices for next-generation electronics and implantable medical equipment. (Credit: Rensselaer/Victor Pushparaj)

Fausto Intilla's web site: www.oloscience.com
_________________
Fausto Intilla
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Biology :: Physicists Discover Inorganic Dust With Lifelike Qualities

Author: admin
Subject: Physicists Discover Inorganic Dust With Lifelike Qualities
Posted: Wed 15/Aug/2007 17:03 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070814150630.htm

Science Daily � Could extraterrestrial life be made of corkscrew-shaped particles of interstellar dust? Intriguing new evidence of life-like structures that form from inorganic substances in space have been revealed in the New Journal of Physics. The findings hint at the possibility that life beyond earth may not necessarily use carbon-based molecules as its building blocks. They also point to a possible new explanation for the origin of life on earth.
Life on earth is organic. It is composed of organic molecules, which are simply the compounds of carbon, excluding carbonates and carbon dioxide. The idea that particles of inorganic dust may take on a life of their own is nothing short of alien, going beyond the silicon-based life forms favoured by some science fiction stories.

Now, an international team has discovered that under the right conditions, particles of inorganic dust can become organised into helical structures. These structures can then interact with each other in ways that are usually associated with organic compounds and life itself.

V.N. Tsytovich of the General Physics Institute, Russian Academy of Science, in Moscow, working with colleagues there and at the Max-Planck Institute for Extraterrestrial Physics in Garching, Germany and the University of Sydney, Australia, has studied the behaviour of complex mixtures of inorganic materials in a plasma. Plasma is essentially the fourth state of matter beyond solid, liquid and gas, in which electrons are torn from atoms leaving behind a miasma of charged particles.

Until now, physicists assumed that there could be little organisation in such a cloud of particles. However, Tsytovich and his colleagues demonstrated, using a computer model of molecular dynamics, that particles in a plasma can undergo self-organization as electronic charges become separated and the plasma becomes polarized. This effect results in microscopic strands of solid particles that twist into corkscrew shapes, or helical structures. These helical strands are themselves electronically charged and are attracted to each other.

Quite bizarrely, not only do these helical strands interact in a counterintuitive way in which like can attract like, but they also undergo changes that are normally associated with biological molecules, such as DNA and proteins, say the researchers. They can, for instance, divide, or bifurcate, to form two copies of the original structure. These new structures can also interact to induce changes in their neighbours and they can even evolve into yet more structures as less stable ones break down, leaving behind only the fittest structures in the plasma.

So, could helical clusters formed from interstellar dust be somehow alive? "These complex, self-organized plasma structures exhibit all the necessary properties to qualify them as candidates for inorganic living matter," says Tsytovich, "they are autonomous, they reproduce and they evolve."

He adds that the plasma conditions needed to form these helical structures are common in outer space. However, plasmas can also form under more down to earth conditions such as the point of a lightning strike. The researchers hint that perhaps an inorganic form of life emerged on the primordial earth, which then acted as the template for the more familiar organic molecules we know today.

Note: This story has been adapted from a news release issued by Institute of Physics.
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Could extraterrestrial life be found in particles of interstellar dust (like that which obscures the giant molecular cloud DR21, shown here in an infrared image taken recently by the orbiting Spitzer Space Telescope)? (Credit: A. Marston (ESTEC/ESA) et al., JPL, Caltech, NASA)

Fausto Intilla's web site: www.oloscience.com
_________________
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Computer Science :: NCAR Adds Resources To TeraGrid

Author: admin
Subject: NCAR Adds Resources To TeraGrid
Posted: Wed 15/Aug/2007 11:35 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070810194742.htm

Science Daily � Researchers who use the TeraGrid, the nation's most comprehensive and advanced infrastructure for open scientific research, can now leverage the computing resources of a powerful, 2048-processor BlueGene/L system at the National Center for Atmospheric Research (NCAR).
NCAR plans to provide up to 4.5 million processor-hours of BlueGene/L computing annually to researchers who have received computing grants from the National Science Foundation (NSF).

The operational integration of TeraGrid with the BlueGene/L system, nicknamed "frost," involved extensive preparation by NCAR's Computational and Information Systems Laboratory (CISL). Engineers deployed the necessary networking infrastructure, then established connectivity to NCAR's data storage systems, and merged the local resource accounting system with the TeraGrid.

"We are excited to be at a point where all our hard work and preparation pays off, and to provide the TeraGrid community with access to this valuable collaborative resource," says Richard Loft, NCAR TeraGrid principal investigator.

NCAR is also testing experimental systems and services on the TeraGrid. These include the wide-area versions of general parallel file systems from IBM and Cluster File Systems, as well as a remote data visualization capability based on the VAPOR tool, an open source application developed by NCAR, the University of California, Davis, and Ohio State University under the sponsorship of NSF.

NCAR's frost system, which is operated in partnership with the University of Colorado, will be the second BlueGene/L system on the TeraGrid, joining the San Diego Supercomputer Center's 6,144 processor system. With the addition of frost, the TeraGrid has more than 250 teraflops of computing capability and more than 30 petabytes of online and archival data storage, with rapid access and retrieval over high-performance networks.

About the TeraGrid

The TeraGrid, sponsored by the National Science Foundation Office of Cyberinfrastructure, is a partnership of people, resources, and services that enables discovery in U.S. science and engineering. Through coordinated policy, grid software, and high-performance network connections, the TeraGrid integrates a distributed set of high-capability computational, data-management and visualization resources to make research more productive.

Note: This story has been adapted from a news release issued by National Center for Atmospheric Research.
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NCAR's fleet of supercomputers is led by BlueGene/L. This IBM machine, a densely-packed, massively parallel computer, requires a fraction of the power and space of most production systems. Joining BlueGene/L at NCAR are a variety of other machines by IBM and other manufacturers. Together, they provide valuable support for scientists at NCAR and those at collaborating universities, who can access the computers remotely for specific projects. (Credit: Copyright University Corporation for Atmospheric Research)

Fausto Intilla's web site: www.oloscience.com
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Mathematics :: Indians Predated Newton 'Discovery' By 250 Years, Scholars..

Author: admin
Subject: Indians Predated Newton 'Discovery' By 250 Years, Scholars..
Posted: Wed 15/Aug/2007 11:31 (GMT 2)
Topic Replies: 0

Source: http://www.sciencedaily.com/releases/2007/08/070813091457.htm

Indians Predated Newton 'Discovery' By 250 Years, Scholars Say.
Science Daily � A little known school of scholars in southwest India discovered one of the founding principles of modern mathematics hundreds of years before Newton -- according to new research.
Dr George Gheverghese Joseph from The University of Manchester says the 'Kerala School' identified the 'infinite series '- one of the basic components of calculus - in about 1350.

The discovery is currently - and wrongly - attributed in books to Sir Isaac Newton and Gottfried Leibnitz at the end of the seventeenth centuries.

The team from the Universities of Manchester and Exeter reveal the Kerala School also discovered what amounted to the Pi series and used it to calculate Pi correct to 9, 10 and later 17 decimal places.

And there is strong circumstantial evidence that the Indians passed on their discoveries to mathematically knowledgeable Jesuit missionaries who visited India during the fifteenth century.

That knowledge, they argue, may have eventually been passed on to Newton himself.

Dr Joseph made the revelations while trawling through obscure Indian papers for a yet to be published third edition of his best selling book 'The Crest of the Peacock: the Non-European Roots of Mathematics' by Princeton University Press.

He said: "The beginnings of modern maths is usually seen as a European achievement but the discoveries in medieval India between the fourteenth and sixteenth centuries have been ignored or forgotten.

"The brilliance of Newton's work at the end of the seventeenth century stands undiminished -- especially when it came to the algorithms of calculus.

"But other names from the Kerala School, notably Madhava and Nilakantha, should stand shoulder to shoulder with him as they discovered the other great component of calculus- infinite series.

"There were many reasons why the contribution of the Kerala school has not been acknowledged - a prime reason is neglect of scientific ideas emanating from the Non-European world - a legacy of European colonialism and beyond.

"But there is also little knowledge of the medieval form of the local language of Kerala, Malayalam, in which some of most seminal texts, such as the Yuktibhasa, from much of the documentation of this remarkable mathematics is written.

He added: "For some unfathomable reasons, the standard of evidence required to claim transmission of knowledge from East to West is greater than the standard of evidence required to knowledge from West to East.

"Certainly it's hard to imagine that the West would abandon a 500-year-old tradition of importing knowledge and books from India and the Islamic world.

"But we've found evidence which goes far beyond that: for example, there was plenty of opportunity to collect the information as European Jesuits were present in the area at that time.

"They were learned with a strong background in maths and were well versed in the local languages.

"And there was strong motivation: Pope Gregory XIII set up a committee to look into modernising the Julian calendar.

"On the committee was the German Jesuit astronomer/mathematician Clavius who repeatedly requested information on how people constructed calendars in other parts of the world. The Kerala School was undoubtedly a leading light in this area.

"Similarly there was a rising need for better navigational methods including keeping accurate time on voyages of exploration and large prizes were offered to mathematicians who specialised in astronomy.

"Again, there were many such requests for information across the world from leading Jesuit researchers in Europe. Kerala mathematicians were hugely skilled in this area."

Note: This story has been adapted from a news release issued by University of Manchester.
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Dr. George Gheverghese Joseph. (Credit: Image courtesy of University of Manchester)

Fausto Intilla's web site: www.oloscience.com
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In the News :: The Beam of Light That Flips a Switch That Turns on the...

Author: admin
Subject: The Beam of Light That Flips a Switch That Turns on the...
Posted: Wed 15/Aug/2007 11:11 (GMT 2)
Topic Replies: 0

Source: http://www.nytimes.com/2007/08/14/science/14brai.html?ref=science
By INGFEI CHEN
Published: August 14, 2007

The Beam of Light That Flips a Switch That Turns on the Brain.

It sounds like a science-fiction version of stupid pet tricks: by toggling a light switch, neuroscientists can set fruit flies a-leaping and mice a-twirling and stop worms in their squiggling tracks.
But such feats, unveiled in the past two years, are proof that a new generation of genetic and optical technology can give researchers unprecedented power to turn on and off targeted sets of cells in the brain, and to do so by remote control.

These novel techniques will bring an �exponential change� in the way scientists learn about neural systems, said Dr. Helen Mayberg, a clinical neuroscientist at Emory University, who is not involved in the research but has seen videos of the worm experiments.

�A picture is worth a thousand words,� Dr. Mayberg said.

Some day, the remote-control technology might even serve as a treatment for neurological and psychiatric disorders.

These clever techniques involve genetically tinkering with nerve cells to make them respond to light.

One of the newest, fastest strategies co-opts a photosensitive protein called channelrhodopsin-2 from pond scum to allow precise laser control of the altered cells on a millisecond timescale. That speed mimics the natural electrical chatterings of the brain, said Dr. Karl Deisseroth, an assistant professor of bioengineering at Stanford.

�We can start to sort of speak the language of the brain using optical excitation,� Dr. Deisseroth said. The brain�s functions �arise from the orchestrated participation of all the different cell types, like in a symphony,� he said.

Laser stimulation can serve as a musical conductor, manipulating the various kinds of neurons in the brain to reveal which important roles they play.

This light-switch technology promises to accelerate scientists� efforts in mapping which clusters of the brain�s 100 billion neurons warble to each other when a person, for example, recalls a memory or learns a skill. That quest is one of the greatest challenges facing neuroscience.

The channelrhodopsin switch is �really going to blow the lid off the whole analysis of brain function,� said George Augustine, a neurobiologist at Duke University in Durham, N.C.

Dr. Deisseroth, who is also a psychiatrist who treats patients with autism or severe depression, has ambitious goals. Brain cells in those disorders show no damage, yet something is wrong with how they talk to one another, he said.

�The high-speed dynamics of the system are probably off,� Dr. Deisseroth said. He wants to learn whether, in these neuropsychiatric diseases, certain neurons falter or go haywire, and then to find a way to tune patients� faulty circuits.

A first step is establishing that it is possible to tweak a brain circuit by remote control and observe the corresponding behavioral changes in freely moving lab animals. On a recent Sunday at Stanford, Dr. Deisseroth and Feng Zhang, a graduate student, hovered over a dark brown mouse placed inside a white plastic tub. Through standard gene-manipulating tricks, the rodent had been engineered to produce channelrhodopsin only in one particular kind of neuron found throughout the brain, to no apparent ill effect.

Mr. Zhang had implanted a tiny metal tube into the right side of the mouse�s partly shaved head.

Now he carefully threaded a translucent fiber-optic cable not much wider than a thick human hair into that tube, positioned over the area of the cerebral cortex that controls movement.

�Turn it on,� Dr. Deisseroth said.

Mr. Zhang adjusted a key on a nearby laser controller box, and the fiber-optic cable glowed with blue light. The mouse started skittering in a left-hand spin, like a dog chasing its tail.

�Turn it off, and then you can see him stand up,� Dr. Deisseroth continued. �And now turn it back on, and you can see it�s circling.�

Because the brain lacks pain receptors, the mouse felt no discomfort from the fiber optic, the scientists said, although it looked a tad confused. Scientists have long known that using electrodes to gently zap one side of a mouse�s motor cortex will make it turn the opposite way. What is new here is that for the first time, researchers can perturb specific neuron types using light, Dr. Deisseroth said.

Electrode stimulation is the standard tool for rapidly driving nerve cells to fire. But in brain tissue, it is unable to target single types of neurons, instead rousing the entire neural neighborhood.

�You activate millions of cells, or thousands at the very least,� said Ehud Isacoff, a professor of neurobiology at the University of California, Berkeley. All variety of neurons are intermixed in the cortex, he said.

Neuroscientists have long sought a better alternative than electrode stimulation. In the past few years, some have jury-rigged ways to excite brain cells by using light; one technique used at Yale made headless fruit flies flap away. But these methods had limitations. They worked slowly, they could not target specific neurons or they required adding a chemical agent.

More recently, Dr. Isacoff, with Dirk Trauner, a chemistry professor at the University of California, Berkeley, and other colleagues engineered a high-speed neural switch by refurbishing a channel protein that anchors in the cell membrane of most human brain cells. The scientists tethered to the protein a light-sensitive synthetic molecular string that has glutamate, a neurotransmitter, dangling off the end.

Upon absorbing violet light, the string plugs the glutamate into the protein�s receptor and sparks a neuron�s natural activation process: the channel opens, positive ions flood inside, and the cell unleashes an electrical impulse.

In experiments published in May in the journal Neuron, the Berkeley team bred zebrafish that carried the artificial glutamate switch within neurons that help sense touch.

�If I were a fish, and somebody poked me in the side,� (in this case, with a fine glass tip), Dr. Isacoff said, �I would escape.� But when the translucent fish were strobed with violet light, the overstimulated creatures no longer detected being prodded. Blue-green light reversed the effect.

One advantage of the Berkeley approach, Dr. Isacoff said, is that it can be adapted for many types of proteins so they could be activated by light. But for the method to work, scientists must periodically douse cells with the glutamate string.

In contrast, Dr. Deisseroth�s laboratory at Stanford has followed nature�s simpler design, borrowing a light-sensitive protein instead of making a synthetic one.

In 2003, Georg Nagel, a biophysicist then at the Max Planck Institute of Biophysics in Frankfurt, and colleagues characterized channelrhodopsin-2 from green algae. This channel protein lets positive ions stream into cells when exposed to blue light. It functioned even when inserted into human kidney cells, the researchers showed.

Neuroscientists realized that this pond scum protein might be used to hot-wire a neuron with light. In 2005, Edward Boyden, then a graduate student at Stanford, Mr. Zhang and Dr. Deisseroth, joining with the German researchers, demonstrated that the idea worked. And in separate research published last spring, Mr. Zhang and Dr. Boyden, now at the Massachusetts Institute of Technology, each found a way to also silence neurons: a bacterial protein called halorhodopsin, when placed in a brain cell, can cause the cell to shut down in response to yellow light.

The Stanford-Germany team put both the �on� and �off� toggles into the motor neurons or muscle cells of transgenic roundworms. Blue light made the creatures contract their muscles and pull back; yellow let them relax their muscles and inch forward.

Dr. Augustine and associates at Duke next collaborated with Dr. Deisseroth to create transgenic mice with channelrhodopsin in different brain cell populations. By quickly scanning with a blue laser across brain tissue, they stimulated cells containing the switch. They simultaneously monitored for responses in connecting neurons, by recording from an electrode or using sensor molecules that light up.

�That way, you can build up a two-dimensional or, in principle, even a three-dimensional map� of the neural circuitry as it functions, Dr. Augustine said.

Meanwhile, other researchers are exploring light-switch technology for medical purposes. Jerry Silver, a neuroscientist at Case Western Reserve University in Cleveland, and colleagues are testing whether they can restore the ability to breathe independently in rats with spinal cord injuries, by inserting channelrhodopsin into specific motor neurons and pulsing the neurons with light.

And in Detroit, investigators at Wayne State University used blind mice lacking photoreceptors in their eyes and injected a virus carrying the channelrhodopsin gene into surviving retinal cells. Later, shining a light into the animals� eyes, the scientists detected electrical signals registering in the visual cortex. But they are still investigating whether the treatment actually brings back vision, said Zhuo-Hua Pan, a neuroscientist.

At Stanford, Dr. Deisseroth�s group has identified part of a brain circuit, in the hippocampus, that is underactive in rats, with some symptoms resembling depression. The neural circuit�s activity � and the animals� � perked up after antidepressant treatment, in findings reported last week in the journal Science. Now the team is examining whether they can lift the rats� low-energy behavior by using channelrhodopsin to rev up the sluggish neural zone.

But human depression is complex, probably involving several brain areas; an easy fix is not expected. The light-switch technologies are not likely to be used for depression or other disorders in people any time soon. One concern is making sure that frequent light exposure does not harm neurons.

Another challenge � except in eye treatments � is how to pipe light into neural tissue. Dr. Deisseroth�s spinning mouse demonstration suggests that fiber optics could solve that issue. Such wiring would be no more invasive, he said, than deep brain stimulation using implanted electrodes, currently a treatment for Parkinson�s disease.

An even bigger obstacle, however, is that gene therapy, a technology that is still unproven, would be needed to slip light-switch genes into a patient�s nerve cells. Clinical trials are now testing other gene therapies against blindness and Parkinson�s in human patients.

But even if those succeed, introducing a protein like channelrhodopsin from a nonmammal species could set off a dangerous immune reaction in humans, warned Dr. Howard Federoff, a neuroscientist at Georgetown University and chairman of the National Institutes of Health committee that reviews all gene-therapy clinical trial protocols in the United States.

In the near term, Dr. Deisseroth predicts that the remote-control technology will lead to new insights from animal studies about how diseases arise, and help generate other treatment ideas.

Such research benefits could extend beyond the realm of neuroscience: The Stanford group has sent DNA copies of the �on� and �off� light-switch genes to more than 175 researchers eager to try them in all stripes of electrically excitable cells, from insulin-releasing pancreas cells to heart cells.
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Thor Swift for The New York Times.
Karl Deisseroth and fiber-optic wires with laser light.

Raag Airan and Karl Deisseroth/Stanford University.
Light stimulation every 200 milliseconds generates electrical activity, right, in an area of the brain associated with depression.

Kim Thompson, Viviana Gradinaru and Karl Deisseroth/Stanford University.
In an optical switch in a mammalian neuron, red marks synapses and green shows photosensitive protein on the cell membrane.

Nature.
STOPPING ON YELLOW A genetically modified C. elegans worm stopped in response to yellow light that inhibits its neural activity.

Fausto Intilla's web site: www.oloscience.com
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Fausto Intilla
(divulgatore scientifico)
www.oloscience.com