July 5, 2007, 8:57 PM CT

The New "Look" Of Superconductivity

Like the surface motif of a bubble bath, the spatial distribution of a magnetic field penetrating a superconductor can exhibit an intricate, foam-like structure. Ruslan Prozorov at the U.S. Department of Energy's Ames Laboratory has observed these mystifying, two-dimensional equilibrium patterns in lead samples when the material is in its superconducting state, below 7.2 Kelvin, or minus 446.71 degrees Fahrenheit.

Through innovative research to relate the complex geometry of the equilibrium patterns to the macroscopic physical properties, such as magnetism, Prozorov has shown that the shape of the entire sample determines the pattern topology and overall magnetic behavior of the system - a significant finding that represents a major contribution to the field of superconductivity. "You can have the same volume and same mass, but if you just change the shape, you get a different type of response from the sample and a different type of geometry of the equilibrium field pattern," he said. "The discovery has reopened the whole field of equilibrium in type-I superconductors, which had gone dormant because it was considered closed." .

Prozorov's discovery of the complex patterns in superconducting lead marks a noteworthy departure from the model first proposed by Russian physicist Lev Landau in the 1930s. Landau's model, which resembles a labyrinth or laminar pattern, has been the unchallenged standard in physics textbooks for 70 years......... Posted by: Kevin      Read more         Source

July 4, 2007, 5:07 AM CT

Urban Growth And Changing Rainfall Patterns

For the first time, researchers have used satellite images to demonstrate a link between rapid city growth and rainfall patterns, as well as to assess compliance with an international treaty to protect wetlands. The results have been published in two studies co-authored by Karen Seto, assistant professor of geological and environmental sciences and a fellow at the Woods Institute for the Environment at Stanford University.

''The exciting thing is really for the first time, using a time series of satellite images, we can monitor Earth in a way that we haven't been able to,'' Seto said. ''It's not just about urban growth or wetlands-it could be about desertification or deforestation-but it's really just this issue of human modification of the Earth.''.

In one study, reported in the July online issue of the journal Global Environmental Change, Seto and her colleagues showed that inclusion in an international environmental agreement did not significantly improve the health of a coastal mangrove habitat in a wetland preserve in Vietnam. In the second study, published May 15 in the Journal of Climate, the scientists observed that rapid urban growth has caused drier winters in the Pearl River Delta of China.

Both findings are based on an analysis of satellite images of Vietnam and China, which NASA has been collecting through its Land Remote-Sensing Satellite (Landsat) Program for more than 30 years......... Posted by: Tyler      Read more         Source

July 4, 2007, 5:00 AM CT

Search for 'weird' life

A new report from the National Research Council, examines the search for life elsewhere in the universe and whether the fundamental requirements for life as we generally know it are the only ways phenomena recognized as "life" could be supported beyond our planet.

Whether "weird" life, as researchers sometimes refer to life with a different biochemical structure than life here, should be considered in the search for extraterrestrial life is looked at in the report......... Posted by: Brooke      Read more         Source

June 29, 2007, 5:08 AM CT

Bright future for nanosized light source

A bio-friendly nano-sized light source capable of emitting coherent light across the visible spectrum, has been invented by a team of scientists with the U.S. Department of Energys Lawrence Berkeley National Laboratory, and the University of California at Berkeley. Among the a number of potential applications of this nano-sized light source, once the technology is refined, are single cell endoscopy and other forms of subwavelength bio-imaging, integrated circuitry for nanophotonic technology, and new advanced methods of cyber cryptography.

Working with individual nanowires, weve developed the first electrode-free, continuously tunable coherent visible light source thats compatible with physiological environments, said chemist Peidong Yang, one of the principal researchers behind this project, and a leading nanoscience authority who holds joint appointments with Berkeley Labs Molecular Foundry and Materials Sciences Division, and the UC Berkeley Chemistry Department.

Weve also demonstrated that it is possible to trap and manipulate single nanowires with optical tweezers, a critical capability not only for bio-imaging but also for wiring together nanophotonic circuitry.

Jan Liphardt, a biophysicist who holds a joint appointment with Berkeley Lab's Physical Biosciences Division and UC Berkeleys Physics Department, was another principal investigator for this research......... Posted by: Kevin      Read more         Source

June 28, 2007, 11:54 PM CT

New, Invisible Nano-fibers

Tiny plastic fibers could be the key to some diverse technologies in the future -- including self-cleaning surfaces, transparent electronics, and biomedical tools that manipulate strands of DNA.

In the recent issue of the journal Nature Nanotechnology, Ohio State University scientists describe how they created surfaces that, seen with the eye, look as flat and transparent as a sheet of glass. But seen up close, the surfaces are actually carpeted with tiny fibers.

The patent-pending technology involves a method for growing a bed of fibers of a specific length, and using chemical therapys to tailor the fibers' properties, explained Arthur J. Epstein, Distinguished University Professor of chemistry and physics and director of the university's Institute for Magnetic and Electronic Polymers.

"One of the good things about working with these polymers is that you're able to structure them in a number of different ways," Epstein said. "Plus, we observed that we can coat almost any surface with these fibers".

For this study, the researchers grew fibers of different heights and diameters, and were able to modify the fibers' molecular structures by exposing them to different chemicals.

They devised one therapy that made the fibers attract water, and another that made the fibers repel water. They found they could also make the surfaces attract or repel oil. Depending on what polymer they start with, the fibers can also be made to conduct electricity......... Posted by: Kevin      Read more         Source

June 27, 2007, 6:20 PM CT

Ready for NASA climate change, ozone mission in tropics

A high-flying NASA mission over Costa Rica and Panama in July and August should help researchers better understand how tropical storms influence global warming and stratospheric ozone depletion, says a University of Colorado at Boulder professor who is one of two mission researchers for the massive field campaign.

Brian Toon, chair of CU-Boulder's atmospheric and oceanic sciences department, said the $12 million effort will mobilize in San Jose, Costa Rica, and involve about 400 scientists, students and support staff operating three NASA aircraft, seven satellites and a suite of other instruments. The team is targeting the gases and particles that flow out of the top of the vigorous storm systems that form over the warm tropical ocean, said Toon.

The warm summer waters of the Pacific Ocean in Central and South America are a breeding ground for heat-driven convective storms targeted by the mission, said NASA officials. Such tropical systems are the major mechanism for Earth's system to loft air into the upper troposphere and stratosphere and are characterized primarily by cumulus clouds with large dense anvils and wispy cirrus clouds.

Known as the Tropical Composition, Cloud and Climate Coupling mission, or TC4, The expedition runs from July 16 through Aug. 8 and is NASA's largest field campaign in several years. The tropical storm systems under study pump air more than 40,000 feet above the surface, where they can influence the make-up of the stratosphere, home of Earth's protective ozone layer......... Posted by: Tyler      Read more         Source

June 27, 2007, 5:42 PM CT

Northern Forests Less Effective in Reducing Global Warming

Forests in the United States and other northern mid- and upper-latitude regions are playing a smaller role in offsetting global warming than previously thought, as per a research studyappearing in this week's issue of Science.

The study, which sheds light on the so-called missing carbon sink, concludes that intact tropical forests are removing an unexpectedly high proportion of carbon dioxide from the atmosphere, thereby partially offsetting carbon entering the air through industrial emissions and deforestation.

The Science paper was written by a team of researchers led by Britton Stephens of the National Center for Atmospheric Research (NCAR) in Boulder, Colo. The research was funded by the National Science Foundation (NSF).

"This research fills in another piece of the complex puzzle on how the Earth system functions," said Cliff Jacobs of NSF's Division of Atmospheric Sciences. "These findings will be viewed as a milestone in discoveries about our planet's 'metabolism.'".

Stephens and colleagues analyzed air samples that had been collected by aircraft across the globe for decades but never before synthesized to study the global carbon cycle. The team observed that some 40 percent of the carbon dioxide assumed to be absorbed by northern forests is instead being taken up in the tropics......... Posted by: Tyler      Read more         Source

June 25, 2007, 7:53 PM CT

Desert Droughts Lead To Earlier Annual Mountain Snow Loss

A new study spearheaded by the University of Colorado at Boulders National Snow and Ice Data Center indicates wind-blown dust from drought-stricken and disturbed lands in the Southwest can shorten the duration of mountain snow cover hundreds of miles away in the Colorado mountains by roughly a month.

Led by Tom Painter, the study found seasonal snow coverage in the sub-alpine and alpine areas of the San Juan Mountains of southwestern Colorado disappeared by about 30 days earlier in 2006 because of heavy dust deposition from the Colorado Plateau roughly 200 miles away. The dust, which probably came from northeast Arizona and northwest New Mexico deserts, reduced the snows reflectivity, allowing more of the suns energy to warm the snow pack and cause it to melt earlier.

The correlation between dust and lower snow reflectance is already established, but the amount of impact measured and modeled in this system stunned us, said Painter. The fact that dust can reduce snow cover duration so much a month earlier -- transforms our understanding of mountain sensitivity to external forcings.

While just three or four significant dust deposition events occurred annually in the San Juan Mountains between 2003 and 2005, eight occurred in 2006, as per the authors. In 2006, the sub-alpine regions of the San Juans melted out 24 to 35 days earlier than previous, relatively dust-free years, as per ground measurements and computer simulations......... Posted by: Tyler      Read more         Source

June 25, 2007, 7:36 PM CT

Building Nanodevices In The Lab

Philadelphia -- Physicists at the University of Pennsylvania are using a new technique to craft some of the tiniest metal nanostructures ever created, none larger than 10 nanometers, or 10,000 times smaller than the width of a single human hair.

The technique employs transmission electron beam ablation lithography, or TEBAL, to carve nanostructures from thin sheets of gold, silver, aluminum and other metals. TEBAL provides a more dependable method for producing quality versions of these microscopic devices, which are studied for their novel mechanical properties and their potential use in next-generation sensors and electronics. The method also permits simultaneous, real-time atomic imaging of the devices as they are made.

Traditional techniques for building nanodevices employ electron beam lithography but also require the use of polymers and chemicals in which the metal is evaporated. Typical results are closer to 50 nanometers in size and rarely as small as 10.

Marija Drndi, professor of physics at Penn, and her team created nanodisks, nanorings, nanowires, nanoholes and multi-terminal nano-transistors. The results were reported in the journal Nano Letters.

A number of different approaches have been undertaken to fabricate the small structures needed to probe the phenomena that take place at the nanoscale, but the most widely used and versatile techniques are limited to tens of nanometers, Drndi said. Reliably and consistently fabricating devices at the sub-10-nanometer scale from the top down is generally still challenging, but our technique offers a route to this regime......... Posted by: Kevin      Read more         Source

June 20, 2007, 1:25 PM CT

New World's first gunshot victim

Peruvian archaeologists have excavated the remains of what they believe to be the earliest documented gunshot victim in the Americas.

The well-preserved skeleton was found in an Inca cemetary located in a suburb of Lima. The skull contains two holes, one at the front, and the other at the back.

Guillermo Cock and Elena Goycochea, who led the dig at the Puruchuco cemetary, have so far found 72 skeletons at the site, at least 35 of which also showed signs of violent death. Some had crushed cheekbones or broken hands, while others appear to have been hacked, torn or impaled. All the bodies were found in shallow graves, and the traditional Inca burial ritual, in which the head faces eastward, was not performed. The bodies therefore appear to have been buried hastily.

Ceramics and other artifacts found at the burial site indicate that the remains date to the 1530s. And an electron microscopic analysis of the skull revealed the presence of miniscule iron particles around the holes, suggesting that the wounds were created by a Spanish musket ball or an arquebus (an early muzzle-loaded firearm). This evidently entered the victim's skull from the back, and exited at the front through the face. This may have been fired from a range of up to 100 feet, while the victim was trying to escape. Subsequently, the team of archaeologists found two other apparent gunshot victims at the site......... Posted by: William      Read more         Source