September 10, 2007, 9:19 PM CT

Icy calculations on global warming

University of Utah mathematicians have arrived at a new understanding of how salt-saturated ocean water flows through sea ice a discovery that promises to improve forecasts of how global warming will affect polar icepacks.

In the current issue of the journal Geophysical Research Letters, math Professor Ken Golden and his colleagues show that brine moving up or down through floating sea ice follows universal transport properties.

It means that almost the exact same formulas describing how water flows through sedimentary rocks in the Earth's crust apply to brine flow in sea ice, even though the microstructural details of the rocks are quite different from sea ice, says Golden, who currently is on an Australian research ship in Antarctica.

The study suggests similar porous materials including ice on other worlds, such as Jupiters icy ocean-covered moon Europa should follow the same rules, he adds.

Golden has made several trips to Antarctica and the Arctic for his studies.

The American Geophysical Union, which publishes the journal carrying Goldens study, says sea ice is important because it is both an indicator and regulator of climate change; its thinning and retreat show the effects of climate warming, and its presence greatly reduces solar heating of the polar oceans......... Posted by: Tyler      Read more         Source

September 6, 2007, 9:35 PM CT

Pinpointing Turbulence in Clouds

A new turbulence detection system now being tested is alerting pilots to patches of rough air as they fly through clouds. The system, designed by the National Center for Atmospheric Research (NCAR) and tested by United Airlines on commercial flights, is designed to better protect passengers from injuries caused by turbulence while reducing flight delays and lowering aviation costs.

The new system uses a mathematical method developed by NCAR scientists, known as the NEXRAD Turbulence Detection Algorithm, or NTDA, to analyze data obtained from the National Weather Service's network of Next-Generation (NEXRAD) Doppler radars. The resulting real-time snapshot of turbulence can be transmitted to pilots in the cockpit and made available to airline meteorologists and dispatchers via a Web-based display.

The research is funded by the Federal Aviation Administration (FAA) in partnership with the National Science Foundation, NCAR's primary sponsor.

"Pinpointing turbulence in clouds and thunderstorms is a major scientific challenge," says NCAR scientist John Williams. "Our goal is to use these radar measurements to create a three-dimensional mosaic showing turbulence across the country that can help pilots avoid hazardous areas, or at least give them enough warning to turn on the 'fasten seat belt' sign"......... Posted by: Tyler      Read more         Source

September 6, 2007, 9:32 PM CT

Sensors Warn Of Emerging Hurricane's Strength

A new study supported by NASA and the U.S. Office of Naval Research takes forecasters one step further to improving their ability to predict just how powerful an oncoming storm may become by using highly-sensitive sensors located thousands of miles from the storm to detect lightning outbreaks within a hurricanes most dangerous area.

Scientists can now investigate with greater accuracy how the rate of lightning strikes produced within a hurricane's eyewall is tied to the changing strength of that hurricane. A hurricanes eyewall is the inner heat-driven region of the storm that surrounds the eye where the most intense rainfall and most powerful winds occur. By monitoring the intensity of lightning near a hurricanes eye, researchers will be able to improve their forecasts of when a storm will unleash its harshest conditions.

During the study, scientists used data from a growing network of new, long-range, ground-based lightning sensors, a NASA satellite and aircraft-based sensors. They explored the relationship between eyewall lightning outbreaks and the intensity of two of the most severe Atlantic storms on record before they made U.S. landfall: category five hurricanes Katrina and Rita. An article on this research, also supported by the U.S. Office of Naval Research, would be reported in the American Meteorological Society's Monthly Weather Review later this year......... Posted by: Tyler      Read more         Source

September 4, 2007, 6:56 PM CT

Computer Scientists Take the Why out of WiFi

People expect WiFi to work, but there is also a general understanding that it's just kind of flakey," said Stefan Savage, one of the UCSD computer science professors who led development of an automated, enterprise-scale WiFi troubleshooting system for UCSD's computer science building. The system is described in a paper presented last week in Kyoto, Japan at ACM SIGCOMM, one of the world's premier networking conferences.

"If you have a wireless problem in our building, our system automatically analyzes the behavior of your connection - each wireless protocol, each wired network service and the a number of interactions between them. In the end, we can say 'it's because of this that your wireless is slow or has stopped working' - and we can tell you immediately," said Savage.

For humans, diagnosing problems in the now ubiquitous 802.11-based wireless access networks requires a huge amount of data, expertise and time. In addition to the myriad complexities of the wired network, wireless networks face the additional challenges of shared spectrum, user mobility and authentication management. Finally, the interaction between wired and wireless networks is itself a source of a number of problems.

"Wireless networks are hooked on to the wired part of the Internet with a bunch of 'Scotch tape and bailing wire' - protocols that really weren't designed for WiFi," explained Savage. "If one of these components has a glitch, you may not be able to use the Internet even though the network itself is working fine."........ Posted by: Kevin      Read more         Source

September 4, 2007, 6:50 PM CT

Beliefs About Early Cherokee Settlement Patterns Likely Incorrect

By 1763, the world of Cherokee Indians in the Southeastern U.S. was in tatters. The French and Indian War had wracked the sprawling Cherokee settlements that stretched from the headwaters of the Savannah River in South Carolina and Georgia to the Overhills towns in eastern Tennessee. Though 75 years would pass before the Trail of Tears would banish the remnants of the nation west to Oklahoma, the tribe watched hopelessly as much of its history rapidly faded.

Scientists have long wondered why the Cherokee settled where they did, building clusters of small towns in fertile river valleys in mostly mountainous areas.

Researchers have also studied why the society collapsed with such relative speed as the eighteenth century unfolded. Now, two new studies show for the first time that long-held assumptions about Cherokee settlement patterns may have been incomplete at best.

"There has been a lot of speculation about these issues, but it's often been outside the realm of evidence," said Ted Gragson, an anthropologist in the University of Georgia's Franklin College of Arts and Sciences. "We were surprised in these studies at the relatively low impact that the Cherokee had on the Southern Appalachian landscape. They really left a very limited footprint on the land they occupied"......... Posted by: William      Read more         Source

September 3, 2007, 11:47 AM CT

Secrets Of Red Tide

In work that could one day help prevent millions of dollars in economic losses for seaside communities, MIT chemists have demonstrated how tiny marine organisms likely produce the red tide toxin that periodically shuts down U.S. beaches and shellfish beds.

In the Aug. 31 cover story of Science, the MIT team describes an elegant method for synthesizing the lethal components of red tides. The scientists believe their method approximates the synthesis used by algae, a reaction that chemists have tried for decades to replicate, without success.

Understanding how and why red tides occur could help researchers figure out how to prevent the blooms, which cause significant ecological and economic damage. The New England shellfish industry, for example, lost tens of millions of dollars during a 2005 outbreak, and red tide killed 30 endangered manatees off the coast of Florida this spring.

The discovery by MIT Associate Professor Timothy Jamison and graduate student Ivan Vilotijevic not only could shed light on how algae known as dinoflagellates generate red tides, but could also help speed up efforts to develop cystic fibrosis drugs from a compound closely correlation to the toxin. Red tides, also known as algal blooms, strike unpredictably and poison shellfish, making them dangerous for humans to eat. It is unknown what causes dinoflagellates to produce the red tide toxins, but it may be a defense mechanism, possibly provoked by changes in the tides, temperature shifts or other environmental stresses......... Posted by: Tyler      Read more         Source

September 3, 2007, 11:45 AM CT

When Bivalves Ruled The World

Before the worst mass extinction of life in Earth's history -- 252 million years ago -- ocean life was diverse and clam-like organisms called brachiopods dominated. After the calamity, when little else existed, a different kind of clam-like organism, called a bivalve, took over.

What can the separate fates of these two invertebrates tell researchers about surviving an extinction event?

A lot, says UWM paleoecologist Margaret Fraiser. Her research into this particular issue not only answers the question; it also supports a relatively new theory for the cause of the massive extinctions that occurred as the Permian period ended and the Triassic period began: toxic oceans created by too much atmospheric carbon dioxide (C02).

The theory is important because it could help researchers predict what would happen in the oceans during a modern "C02 event." And it could give them an idea of what recovery time would be.

Studying the recovering ecology is equally significant, says Fraiser. The evolution of surviving species in the aftermath of the mass extinction set the stage for dinosaurs to evolve later in the Triassic.

From air to water Fossil records suggest that trauma in the oceans actually began in the air.

"Estimates of the C02 in the atmosphere then were between six and 10 times greater than they are today," says Fraiser, an assistant professor of geosciences. It makes sense, she says. The largest continuous volcanic eruption on Earth -- known as the "Siberian Traps" -- had been pumping out C02 for about a million years previous to the Permian-Triassic mass extinction......... Posted by: William      Read more         Source

September 3, 2007, 11:43 AM CT

Looking For Life In And Under Antarctic Ice

Antarctica is home to the largest body of ice on Earth. Previous to approximately 10 years ago, no one thought that life could exist beneath the Antarctic ice sheets, which can be more than two miles thick in places, because conditions were thought to betoo extreme. However, Brent Christner, assistant professor of biological sciences at LSU, has spent a great deal of time in one of the world's most hostile environments conducting research that proves otherwise.

Christner's discoveries of viable microbes in ancient ice cores and subglacial environments coupled with the realization that large quantities of liquid water exist beneath the Antarctic ice sheet have changed the way biologists view life in Antarctica.

"More than 150 lakes have been discovered underneath nearly two-and-a-half miles of ice in Antactica," said Christner, "and most of these bodies of water have likely been covered by ice for at least 15 million years. The environmental conditions in the deep cold biosphere are unlike anything on the Earth's surface and this represents one of the most extreme habitats for life on the planet".

A time frame of up to one million years is mandatory for microbes in the atmosphere to be transported through the ice sheet and enter an Antarctic subglacial lake. Even though cells are preserved in the ice, the question of how the DNA of these organisms remains unscathed over such long periods of apparent metabolic inactivity still remains......... Posted by: Tyler      Read more         Source

September 3, 2007, 11:27 AM CT

Low-cost Recipe For Patterning Microchips

Creating ultrasmall grooves on microchips -- a key part of a number of modern technologies -- is about to become as easy as making a sandwich, using a new process invented by Princeton engineers.

The simple, low-cost technique results in the self-formation of periodic lines, or gratings, separated by as few as 60 nanometers -- less than one ten-thousandth of a millimeter -- on microchips. Features of this size have a number of uses in optical, biological and electronic devices, including the alignment of liquid crystals in displays. The scientists will publish their findings Sept. 2 in the online version of Nature Nanotechnology.

Its like magic, said electrical engineer Stephen Chou, the Joseph C. Elgin Professor of Engineering. This is a fundamentally different way of making nanopatterns.

The process, called fracture-induced structuring, is as easy as one-two-three. First, a thin polymer film is painted onto a rigid plate, such as a silicon wafer. Then, a second plate is placed on top, creating a polymer sandwich that is heated to ensure adhesion. Finally, the two plates are pried apart. As the film fractures, it automatically breaks into two complementary sets of nanoscale gratings, one on each plate. The distance between the lines, called the period, is four times the film thickness......... Posted by: Kevin      Read more         Source

August 31, 2007, 4:50 AM CT

Population movements, money and forest regrowth

A study of forest cover in El Salvador in the recent issue of BioScience presents novel findings on how economic globalization, land policy changes, and monies sent to family members by emigrants have transformed agriculture and stimulated forest regrowth. The study, by Susanna B. Hecht and Sassan S. Saatchi, employed socioeconomic data, land-use surveys, and satellite imagery to document substantial increases in the area of El Salvador covered by both light and heavy woodland since peace accords were signed in 1992.

Most analyses of forest cover in Central America have focused on loss of old-growth forests. In drawing attention to regrowth of woodland in a country that was extensively deforested during the 1970s, Hecht and Saatchi call for a renewed examination of social and economic influences on agricultural practices and their effects on forest extent. New growth forests, most often in a mosaic along with agriculture, can buffer declines in biological diversity and are extensively used by old growth species.

War drove a number of people to flee El Salvador during the 1980s and early part of 1990s, which led to a number of farms being abandoned. The country experienced a net increase in tree cover thereafter. Hecht and Saatchi found a 22 percent increase in the area with 30 percent tree cover, and a 6.5 percent increase in the area with more than 60 percent tree cover. Policies that encouraged sustainable agriculture contributed to the increase, the authors maintain......... Posted by: Tyler      Read more         Source