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March 5, 2007, 4:26 PM CT

New Nanoelectronic Switch

New Nanoelectronic Switch
Scientists at the National Institute of Standards and Technology (NIST) have demonstrated a prototype nanoscale electronic switch that works like lightning-except for the speed. Their proof-of-concept experiments reported last week* demonstrate that nanoscale electrical switches can be built from self-assembled layers of organic molecules on silver wires. Potential applications range from a replacement technology for magnetic data storage to integrated circuit memory devices.

Silver would be a natural choice for nanoscale and microscale electrical contacts because of its high conductivity, but it has one notorious drawback. In an electric field, silver ions readily form silver "whiskers," tree-like branching growths of crystals that can short-out microelectronic devices.

Two NIST scientists have demonstrated that this can be a feature, not a bug, in an elegant experiment that uses this growth to make a nanoscale binary switch. In the experiment, an extremely fine silver wire is coated with a molecule that forms a self-assembled monolayer on the wire, typically some organic molecule with a sulfur group on one end to bond to the silver. An equally fine gold wire is laid crosswise to the silver wire and a small voltage is applied across the two wires. When the voltage is increased to a critical level, silver ions form and quickly branch through the organic monolayer to the gold wire just like a lightning bolt-except solid. When a silver filament reaches the gold, it forms a short circuit, causing a dramatic change in conductance, which is easily detectable. Reversing the voltage retracts the filament and "opens" the switch.........

Posted by: John      Read more         Source


March 5, 2007, 4:12 PM CT

Conflicting Signals For Rescue Robots

Conflicting Signals For Rescue Robots Image courtesy of rescue-robot-contest.org
Sensor-laden robots capable of vital search and rescue missions at disaster sites are no figment of a science fiction writer's imagination. Prototypes and commercial models of urban search and rescue (US&R) robots will soon begin to work rubble piles across the country. Too a number of of these lifesaving robots, however, could be too much of a good thing, as per scientists at the National Institute of Standards and Technology (NIST), who report that the radio transmissions of multiple robots can interfere with each other and degrade search and rescue performance.

A NIST analysis of wireless radio field trials for US&R robots, presented at a conference on February 28,* observed that 10 out of the 14 robots tested experienced communication problems due to radio interference from other systems. Engineers carried out tests on the robots last August at a US&R robot standards development gathering in Gaithersburg, Md., sponsored by the Department of Homeland Security. The scientists observed that neither use of "industrial, scientific, and medical" (ISM) frequency bands nor adherence to protocols designed to minimize interference between systems in the bands could guarantee flawless communication between a robot and its human operator. Radio interference could happen whenever the ISM frequency bands became crowded or when one user had a much higher output power than the others. An example of the latter problem occurred during the tests when transmitters in the 1760 MHz band knocked out video links in the 2.4 GHz frequency band. In another case, a robot using an 802.11b signal in the 2.4 GHz band overwhelmed and cut off a robot that had been transmitting an analog video link at 2.414 GHz.........

Posted by: John      Read more         Source


March 2, 2007, 5:03 AM CT

Heatwave on the top of the world

Heatwave on the top of the world
The French Intergovernmental Panel on Climate Change (IPPC, or GIEC in French) has just announced the conclusions of its 4th report, which restates that global warming has increased the average temperature by 0.74C over the last century. However, there is very little information about some parts of the planet, such as central Asia. A new study by French researchers from the Laboratory of Glaciology and Geophysics of the Environment (LGGE, CNRS / Universit Joseph Fourier, Grenoble, France) and the Laboratory of Sciences of the Cliamte and the Environment (LSCE / IPSL, CEA / CNRS / Universit de Versailles Saint-Quentin, France), in collaboration with Chinese, Russian and American researchers, proves that the recent warming has also affected the ice cap on Mount Everest, in the heart of the Himalayas. This result was published on February 7, 2007 in the European Journal "Climate of the Past".

Relatively little is known about climate change in the Himalayas and the Tibetan plateau. There are very few meteorological stations, and instrumental records from glaciers, lakes or tree growth rings are rare and difficult to interpret. However, in 2001 and 2002, Chinese scientists drilled three ice cores in the eastern summit of the East Rongbuk glacier that covers the north pass of Mount Everest, at 6518 meters above sea level. These ice cores were analyzed in collaboration with the LGGE and the LSCE, and they have shown that a new climate marker exists, the ice core gas content, which can reconstruct the changes in summer temperatures on this very high site.........

Posted by: Nora      Read more         Source


March 1, 2007, 10:03 PM CT

Atomic Processes In Nanomaterials

Atomic Processes In Nanomaterials Image courtesy / Subra Suresh
Scientists from MIT, Georgia Institute of Technology and Ohio State University have developed a new computer modeling approach to study how materials behave under stress at the atomic level, offering insights that could help engineers design materials with an ideal balance between strength and resistance to failure.

When designing materials, there is often a tradeoff between strength and ductility (resistance to breaking)--properties that are critically important to the performance of materials.

Recent advances in nanotechnology have allowed scientists to manipulate a material's nanostructure to make it both strong and ductile. Now, the MIT-related team has figured out why some nano-designed metals behave with that desirable compromise between strength and ductility.

The team, led by Subra Suresh, the Ford Professor of Engineering in the Department of Materials Science and Engineering, developed a simulation method derived from experimental data that allows them to visualize the deformation of materials on a timescale of minutes. Prior methods allowed for only a nanosecond-scale glimpse at the atomic-level processes.

"It's a method to look at mechanical properties at the atomic scale of real experiments without being bogged down by limitations of nanosecond timescales of the simulation methods such as molecular dynamics," said Suresh, the senior author of a paper on the work that appears as the cover story in the Feb. 27 issue of the Proceedings of the National Academy of Sciences.........

Posted by: John      Read more         Source


March 1, 2007, 9:48 PM CT

A frenzy of fruit fly methods

A frenzy of fruit fly methods
For the past century, fruit fliesor Drosophilahave provided innumerable insights into the genetics and biology of development, learning and memory, behavior, vision, and other processes. But for researchers who conduct these studies, the logistics of housing and feeding the hundreds or thousands of flies needed for experiments can be daunting. To address this concern, the current issue of Cold Spring Harbor Protocolsreleased online today www.cshprotocols.org includes a series of articles for maintaining and manipulating flies in the laboratory.

One of the articles, freely accessible at http://www.cshprotocols.org/cgi/content/full/2007/6/pdb.ip35, provides tried-and-true advice on how to maintain fly stocks, set up appropriate matings, and control contamination and diseases. Because flies are considered a premier model organism for genetics studies, the featured article also presents techniques for inducing mutations into the DNA of flies. The article will be useful for biologists starting to work with flies in the laboratory, as well as for existing fly laboratories looking to reorganize.

Other articles published recently include methods for harvesting and analyzing fly embryos, as well as protocols for characterizing proteins from a variety of sources. These publications join in a growing library of high-quality methods from Cold Spring Harbor Protocols For a complete list of freely accessible protocols.........

Posted by: Nora      Read more         Source


February 28, 2007, 9:51 PM CT

Through Precariously Balanced Rocks

Through Precariously Balanced Rocks Image courtesy of patrick.wattle.id.au
A seismological research team from the University of Nevada, Reno is finding ways to make precariously balanced rocks talk. In so doing, they are unlocking valuable scientific information in assessing seismic hazards in areas throughout the West.

Their findings are shared in the January-recent issue of American Scientist magazine. Scientists believe that zones of precarious rocks rocks that have come close but haven't tipped over in the wake of a major seismic event provide important information about seismic risk, its magnitude and its frequency.

"There's really no long-term data to test seismic hazards other than precarious rocks," said Matthew Purvance, a postdoctoral scholar in geophysics at the University, who authored the article along with James Brune, professor in the Department of Geological Sciences and past director of the Nevada Seismological Laboratory, and Rasool Anooshehpoor, research professor in the Nevada Seismological Laboratory.

"By studying precariously balanced rocks, it can serve as an indicator that an earthquake of a sufficient size to topple a tippy rock has not occurred at least for a very long time. We think this is a fundamental story that gives fundamental information on seismic hazards that has never been done before".........

Posted by: Nora      Read more         Source


February 27, 2007, 9:24 PM CT

Brain maps online

Brain maps online
Digital atlases of the brains of humans, monkeys, dogs, cats, mice, birds and other animals have been created and posted online by researchers at the UC Davis Center for Neuroscience.

BrainMaps.org features the highest resolution whole-brain atlases ever constructed, with over 50 terabytes of brain image data directly accessible online. Users can explore the brains of humans and a variety of other species at an unprecedented level of detail, from a broad view of the brain to the fine details of nerves and connections. The website also includes a suite of free, downloadable tools for navigating and analyzing brain data.

"Many users have described it as a 'Google Maps' of the brain," said Shawn Mikula, a postdoctoral researcher at UC Davis who is first author on a paper describing the work.

The high-resolution maps will enable researchers to use "virtual microscopy" to compare healthy brains with others, looking at structure, gene expression and the distribution of different proteins. They will enable better understanding of the organization of normal brains, and could help researchers in identifying fine morphological and chemical abnormalities underlying Alzheimer's, Parkinson's and other neurological diseases, Mikula said.

To make the maps, the researchers started with sections of brain mounted on microscope slides. Those slides were scanned to create image files or "virtual slides," and assembled like tiles into composite images. The maps have a resolution of better than half a micrometer per pixel, or 55,000 dots per inch, with virtual slides approaching 30 gigabytes in size each.........

Posted by: Nora      Read more         Source


February 27, 2007, 8:42 PM CT

UK Fellowships for Women in Science

UK Fellowships for Women in Science
The L'Oreal UK Fellowships For Women In Science, organised in partnership between L'Oreal UK, the Royal Institution of Great Britain and the UK National Commission for UNESCO, are designed to celebrate and support the contribution of UK women scientists in the life and physical sciences.

Three fellowships, each valued at £10,000, will be offered to outstanding female researchers and are tenable at any UK university or research institution to support 12 months of post-doctoral research. The prize money can be spent in any number of innovative ways to enable women researchers to further their scientific careers and facilitate world class scientific research.

An application form, guidelines and further details can be found on either the Royal Institution of Great Britain website or the UK National Commission for UNESCO website. The deadline for applications is Wednesday April 18 2007.

For more information Email: Pat.Carter@pparc.ac.uk.........

Posted by: Nora      Read more         Source


February 27, 2007, 8:00 PM CT

About The Extrasolars

About The Extrasolars This artist's concept shows a cloudy Jupiter-like planet, similar to HD 209458b, that orbits very close to its fiery hot star. Image / NASA/JPL-Caltech/T. Pyle (SSC)
So far, astronomers have discovered about 200 planets outside our solar system, known as "extrasolar" planets. Very little is known about most of them, but for the first time, researchers have obtained new information about the atmospheres of two such planets by splitting apart the light emitted from them.

Sara Seager, MIT associate professor of earth, atmospheric and planetary sciences, is part of a research group based at Goddard Space Flight Center that studied a planet about 904 trillion miles from Earth, known as HD 209458b. The scientists used NASA's Spitzer Space Telescope to capture the most detailed information yet about an extrasolar planet.

Seager's team is one of three that are reporting spectral observations of extrasolar planets this week. Two groups studied HD 209458b, and one studied another planet in a different solar system. The work by Seager's team is published in the Feb. 22 issue of Nature.

Astronomers often learn about distant objects, such as stars and galaxies, by studying the composition of light emitted by them, Seager said. But extrasolar planets are much dimmer than stars and thus far more difficult to study.

Light from extrasolar planets is "very, very hard to measure because the stars are so bright and the planets are faint. This planet is right at the edge of what we can detect with this telescope," said Seager, who arrived at MIT in January to start a program devoted to studying extrasolar planets.........

Posted by: Edwin      Read more         Source


February 27, 2007, 7:58 PM CT

It's not for the fruit

It's not for the fruit
Why do some birds fly thousands of miles back and forth between breeding and non-breeding areas every year whereas others never travel at all? One textbook explanation suggests that eating fruit or living in nonforested environments were the precursors needed to evolve migratory behavior. Not so, report ecologists W. Alice Boyle and Courtney J. Conway of the University of Arizona, Tucson, in the recent issue of the American Naturalist. Conway is also a research scientist with the U.S. Geological Survey. The two showed the pressure to migrate comes from seasonal food scarcity. It's the first time the technique called phylogenetic independent contrasts has been used to identify the causes of bird migration. "It's not just whether you eat insects, fruit, or candy bars, or where you eat them it matters how reliable that food source is from day-to-day," Boyle said. "For example, some really long-distance migrants like Arctic Terns are not fruit-eaters".

The new research indicates that one strategy for dealing with seasonal changes in food availability is migration. The team also found that birds that forage with others of the same species are less likely to migrate. "Flocking can be an alternative way of dealing with food shortages," Boyle said. When birds band together to search for food, the group is more likely to find a new patch of food than is one lone individual. To figure out the underlying pressures that drive some birds to leave home for the season, Boyle and Conway focused on 379 species of New World flycatchers from the suborder Tyranni. For all those species the scientists compared the species' size, food type, habitat, migratory behavior, and whether the birds fed in flocks. A universal assumption about bird migration has been that short-distance migration is an evolutionary stepping stone to long-distance migration. The team's work contradicts that idea by showing that short-distance migrants are inherently different from their globe-trotting cousins.........

Posted by: Nora      Read more         Source


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