May 10, 2007, 10:31 PM CT

Electrons Caught in the Act of Tunnelling

In the same way as gravity brings a body to a halt on the floor of a valley, the nuclear force (which binds protons and neutrons to form the atomic nucleus) and the electrical force (which combines negatively charged electrons with the positively charged atomic nucleus to make an atom) hold these particles within a tiny space. This binding effect can also be depicted as a type of valley, which is also called a potential by physicists. In the world of quantum particles, it is, to a certain extent, a normal event to tunnel through the wall surrounding the potential well. An international team of scientists working with Ferenc Krausz has now caught the electrons in the act of tunnelling through the binding potential of the atom nucleus under the influence of laser light. The physicists used the new tools provided by attosecond metrology. "For the first time, our findings confirmed in real time observation the theoretical predictions of quantum mechanics," says Ferenc Krausz, Director at the Max Planck Institute for Quantum Optics and head of the team of scientists.

The tunnelling effect can be explained by the wave behaviour of each particle. Macroscopic objects are extremely unlikely to tunnel, which is why the phenomenon has never been observed in them. In contrast, there is a significant probability that particles from the microcosmos will tunnel through areas where, as per the rules of traditional physics, they are not even supposed to be. The tunnelling effect is considered to be responsible for processes as varied as atomic nuclei decay and the switching process in electronic components. However, since it only lasts for an extremely short time, it has still not been observed in real time......... Posted by: Sarah      Read more         Source

May 9, 2007, 11:12 PM CT

Genome Sequencing Of The First Marsupial

Since the launch of the Human Genome Project, which released a first draft of the entire sequence of human DNA in 2001, a number of scientists have dedicated themselves to creating a library of comprehensive, species-specific genetic sequence "maps" available for study. Researchers at LSU recently took part in a multi-institutional effort spearheaded by the Broad Institute of MIT and Harvard University to sequence the complete genome of the gray, short-tailed opossum, Monodelphis domestica.

As the first marsupial, a mammal equipped with a special "pouch," to be sequenced, the opossum provides a unique perspective on the organization and evolution of mammalian genomes. The results would be reported in the journal Nature on Thursday, May 10.

Marsupials diverged from a common ancestor with placental mammals, a group including humans, approximately 180 million years ago. Marsupials and placental mammals are more closely correlation to one another than to any other vertebrate model species, such as birds, amphibians or fish, yet marsupials are also genetically distinct from all current mammalian biomedical research models. This makes the marsupial an integral part of evolutionary and biomedical studies.

Kangaroos of Australia and the North American opossum, which is abundant in Louisiana, typically come to mind when one thinks of marsupials. However, Monodelphis domestica, a South American opossum, was chosen for genome sequencing because it is the predominant laboratory-bred research marsupial in the world and therefore represents an important model organism for comparative genomics. Studies in this species will help to identify genome features common to all mammals and will also help to pinpoint specific differences between placental and non-placental mammals......... Posted by: Ashley      Read more         Source

May 9, 2007, 10:30 PM CT

New Materials To Make Hydrogen More Stable

Carnegie Mellon University's David S. Sholl is working to identify new materials that would help make hydrogen more stable and cost-efficient than fossil fuels. Increased concern about global warming and a need to conserve natural fuel sources prompted Carnegie Mellon scientists to find new, lightweight, low-cost hydrogen-storage materials.

"We are currently studying the use of metal hydrides, such as alanates and borohydrides, to find materials that could ultimately improve the efficiency of hydrogen cars and curb pollution," said Sholl, a professor of chemical engineering.

Essentially, what Sholl and his research team are trying to do is create a new material that will store larger amounts of hydrogen than can be held in a compressed gas tank, but will still be able to easily release the hydrogen to feed the fuel cell for cars of the future. Hydrogen-powered cars run on fuel cells that combine hydrogen and oxygen from the air to produce electricity. The only waste emitted is water.

By contrast, engines that burn gasoline emit pollutants, such as carbon dioxide, that cause global warming. U.S. vehicles consume 383 million gallons of gasoline a day or about 140 billion gallons annually. That's about two-thirds of the total national oil consumption, half of which is imported from overseas......... Posted by: Sarah      Read more         Source

May 9, 2007, 10:27 PM CT

extreme summer warming in the future

A new study by NASA researchers suggests that greenhouse-gas warming may raise average summer temperatures in the eastern United States nearly 10 degrees Fahrenheit by the 2080s.

"There is the potential for extremely hot summertime temperatures in the future, particularly during summers with less-than-average frequent rainfall," said lead author Barry Lynn of NASA's Goddard Institute for Space Studies and Columbia University, New York.

The research observed that eastern U.S. summer daily high temperatures that currently average in the low-to-mid-80s (degrees Fahrenheit) will most likely soar into the low-to-mid-90s during typical summers by the 2080s. In extreme seasons when precipitation falls infrequently July and August daily high temperatures could average between 100 and 110 degrees Fahrenheit in cities such as Chicago, Washington, and Atlanta.

To reach their conclusions, the scientists analyzed nearly 30 years of observational temperature and precipitation data and also used computer model simulations that considered soil, atmospheric, and oceanic conditions and projected changes in greenhouse gases. The simulations were produced using a widely-used weather prediction model coupled to a global model developed by NASA's Goddard Institute for Space Studies......... Posted by: Tyler      Read more         Source

May 6, 2007, 5:26 PM CT

CT imaging and car crash testing

Crash test injuries analyzed with CT imaging provide valuable data that can help engineers develop safer cars and reduce the severity of injuries during car accidents, as per a new study by scientists from The Ohio State University in Columbus.

For the study, two human cadavers were hit with a device that simulates a blunt impact equivalent to car collisions. CT imaging of the rib cages of the cadavers waccording toformed to evaluate the damage caused by the impact. "We observed that injuries to the rib cage caused by the simulated car collision could be identified on the Computerized axial tomography scans and that the CT results correlated with the usual, more involved methods of body damage analysis, which makes use of high speed videos and data from sensors attached to more than 30 locations on the body during the impact," said Steffen Sammet, MD, PhD, lead author of the study.

"The study was initiated by a project from the Department of Transportation to enable objective, noninvasive measures of crash impacts. The knowledge gained from those tests goes directly into automotive engineering to prevent those disabling injuries or death," said Dr. Sammet.

In addition to saving lives through the design of safer cars, the scientists foresee other possible uses for the data gathered from CT imaging of crash tests. "A direct further outcome of this research is understanding how imaging findings correlate to the force of impact, which can further improve our ability to provide better diagnosis as well as help in the understanding of forensic aspects of car crashes," said Dr. Sammet......... Posted by: Sean      Read more         Source

May 6, 2007, 4:46 PM CT

Creating corn for cars

A new variety of corn developed and patented by Michigan State University researchers could turn corn leaves and stalks into products that are just as valuable as the golden kernels.

Right now, most U.S. ethanol is made from corn kernels. This is because breaking down the cellulose in corn leaves and stalks into sugars that can be fermented into ethanol is difficult and expensive.

"We've developed two generations of Spartan Corn," said Mariam Sticklen, MSU professor of crop and soil sciences. "Both corn varieties contain the enzymes necessary to break down cellulose and hemicellulose into simple sugars in their leaves. This will allow for more cost-effective, efficient production of ethanol".

Sticklen will co-chair a panel on energy crops for biofuels today at BIO2007, the annual international convention of the Biotechnology Industry Organization.

"In the future, corn growers will be able to sell their corn stalks and leaves as well as their corn grain for ethanol production," Sticklen said. "What is now a waste product will become an economically viable commodity"......... Posted by: Kevin      Read more         Source

April 30, 2007, 9:17 PM CT

Case Study In Emissions

The Chinese government's restrictions on Beijing motorists during a three-day conference last November -- widely viewed as a dress rehearsal for efforts to slash smog and airborne pollutants during the 2008 Summer Olympic Games in Beijing -- succeeded in cutting the city's emissions of one important class of atmospheric gases by an impressive 40 percent.

That's the conclusion of Harvard University scientists Michael B. McElroy, Yuxuan Wang, and K. Folkert Boersma, who used data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) to assess the drop in emissions. The researchers detail their work this week in the journal Geophysical Research Letters.

"I don't think a proper analysis has ever been made before of such a remarkable shift of environmental policy in such a short period of time," says McElroy, the Gilbert Butler Professor of Environmental Studies in Harvard's Faculty of Arts and Sciences and School of Engineering and Applied Sciences.

China's restrictions on Beijing drivers coincided with the Summit of the Forum on China-Africa Cooperation from Nov. 4-6, 2006, during which an estimated 800,000 of Beijing's 2.82 million vehicles were taken off the road. The OMI -- aboard NASA's Aura satellite, launched in 2004 -- documented a 40 percent reduction in NOx, a class of nitrogen oxides formed during combustion, while the restrictions were in place. These greenhouse gas emissions are thought to contribute, in part, to global warming......... Posted by: Tyler      Read more         Source

April 29, 2007, 7:25 PM CT

The Chimpanzee Stone Age

Before this study, chimpanzees were first observed using stone tools in the 19th century. Now, thanks to this new archaeological find, tool use by chimpanzees has been pushed back thousands of years. The authors suggest this type of tool use could have originated with our common ancestor, instead of arising independently among hominins and chimpanzees or through imitation of humans by chimpanzees.

This study confirmed that chimpanzees and human ancestors share for thousands of years several cultural attributes once thought exclusive of humanity, including transport of raw materials across the landscape; selection and curation of raw materials for a specific type of work and projected usage; habitual reoccupation of sites where garbage and debris accumulate; and the use of locally available resources. Nut cracking behaviour in chimpanzees is transmitted socially, and the new discoveries presented in this study shows that such behaviour has been transmitted over the course of a number of chimpanzee generations. Chimpanzee prehistory has deep roots!

The study of our living closest relative, the chimpanzee, constantly highlights new aspects of human evolution, and a better protection of this endangered species will guarantee that we can continue uncovering new facets of our past. Relevant finds come from all parts of the African continent, including the rainforest, and not just the classical east African homeland......... Posted by: William      Read more         Source

April 29, 2007, 7:11 PM CT

Volcanoes and Nanotechnology

Since their discovery in the early part of 1990s, carbon nanotubes and carbon nanofibers-tiny structures made of pure carbon-have been used in a wide variety of applications. They have become indispensable in the nanosciences and nanotechnology. However, because their production on an industrial scale remains expensive, their commercial use in such areas as catalysis has remained unthinkable. This could now be changing, thanks to scientists from the Fritz Haber Institute in Berlin: Dang Sheng Su and his co-workers have used igneous rock from Mount Etna to produce carbon nanotubes and fibers directly by deposition from the gas phase. As they explain in the journal Angewandte Chemie, the naturally occurring iron oxide particles in lava make it an effective natural catalyst, possibly smoothing the way to a more efficient production method.

Etna is the most active European volcano. During its especially violent eruptions in 2002 and 2003, several million cubic meters of lava were ejected. The fertility of mineral-rich volcanic soils has long been known; Su and colleagues wanted to elicit another, completely new sort of "fertility" for science. It could be amazingly helpful in the synthesis of carbon nanotubes and fibers.

Lava rock is extremely porous and contains large quantities of finely divided iron oxides. This is just what is needed for the synthesis of these tiny carbon structures. The scientists pulverize the rocks and heat them to 700 degree C under a hydrogen atmosphere. This reduces the iron oxide particles to elemental iron. When a mixture of the gases hydrogen and ethylene is directed over the powder, the iron particles catalyze the decomposition of ethylene to elemental carbon. This is deposited on the lava rock in the form of tiny tubes and fibers. The advantages of this new method? The catalyst is produced naturally in large quantities and is thus affordable; the catalytic iron does not need to be deposited on any kind of substrate, as the lava is both catalyst and substrate in one; and this process works without any "wet" chemical steps......... Posted by: Kevin      Read more         Source

April 29, 2007, 7:09 PM CT

A New Type Of Very-high-energy Gamma Ray Emitter

An international team of astrophysicists from the H.E.S.S. collaboration has announced the discovery of a new type of very-high-energy (VHE) gamma ray source. Combining data obtained during a systematic survey of the Galactic Plane and dedicated pointed observations of the telescope array revealed energetic gamma radiation coincident with the stellar cluster Westerlund 2, which is embedded in the giant ionized hydrogen cloud RCW49. The new VHE source, HESS J1023-575, is a first indication of extreme particle acceleration linked to a young open stellar cluster, an ensemble of stars which are especially interesting due to ongoing star formation and the existence of extremely massive stars, known as Wolf-Rayet (WR) stars. One of these, WR 20a, a close binary systems of two WR stars orbiting each other, is the most massive of all confidently-measured binaries presently known in our Galaxy.

Wolf-Rayet stars (named for their discoverers) are evolved, massive stars near the end of their stellar live-cycle, when they are rapidly losing their mass by means of supersonic stellar winds. In the Westerlund 2 cluster, the Wolf-Rayet winds have literally blown bubbles around their stellar hosts, clearly visible in infrared and radio images of the region. Integrated over their lifetime, the wind energy output of Wolf-Rayet stars is not too far from the kinetic energy released in supernova explosions, and shocked winds a re well suited to accelerate particles to high energy......... Posted by: Kevin      Read more         Source