November 21, 2006, 8:53 PM CT

Historic Volcanic Eruption Shrunk the Mighty Nile

Volcanic eruptions in high latitudes can greatly alter climate and distant river flows, including the Nile, according to a recent study funded in part by NASA.

Researchers found that Iceland's Laki volcanic event, a series of about ten eruptions from June 1783 through February 1784, significantly changed atmospheric circulations across much of the Northern Hemisphere. This created unusual temperature and precipitation patterns that peaked in the summer of 1783, including far below normal rainfall over much of the Nile River watershed and record low river levels.

The study provides new evidence that large volcanic eruptions north of the equator often have far different impacts on climate than those in the tropics. "While considerable research has shown that eruptions in the tropics influence climate in the Northern Hemisphere winter, this study indicates that eruptions in high-latitudes produce changes in atmospheric circulation in the Northern Hemisphere summer," said lead author Luke Oman, Rutgers University, New Brunswick, N.J. Using a sophisticated computer model developed by NASA's Goddard Institute for Space Studies, New York, the researchers linked the Laki eruptions to a cascade of effects that rippled across much of the Northern Hemisphere, altering surface temperatures that ultimately resulted in much below normal rainfall over the Sahel of Africa and record low water levels on the Nile River for up to a year. The Sahel is a stretch of land from the Atlantic Ocean to the "Horn of Africa" that includes the Sahara Desert and savanna areas with sparse vegetation.........

Posted by: Beverly      Permalink         Source

November 21, 2006, 8:39 PM CT

Ultra-Intense Laser Blast Creates True 'Black Metal'

"Black gold" is not just an expression anymore. Scientists at the University of Rochester have created a way to change the properties of almost any metal to render it, literally, black.

The process, using an incredibly intense burst of laser light, holds the promise of making everything from fuel cells to a space telescope's detectors more efficient-not to mention turning your car into the blackest black around.

"We've been surprised by the number of possible applications for this," says Chunlei Guo, assistant professor of optics at the University of Rochester. "We wanted to see what would happen to a metal's properties under different laser conditions and we stumbled on this way to completely alter the reflective properties of metals".

The key to creating black metal is an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse. The laser burst lasts only a few quadrillionths of a second. To get a grasp of that kind of speed-a femtosecond is to a second what a second is to about 32 million years.

During its brief burst, Guo's laser unleashes as much power as the entire grid of North America onto a spot the size of a needle point. That intense blast forces the surface of the metal to form and nanostructures-pits, globules, and strands that both dramatically increase the area of the surface and capture radiation. Some larger structures also form in subsequent blasts.........

Posted by: Beverly      Permalink         Source

November 21, 2006, 5:13 AM CT

Clues From Dragonfly About Human Obesity

Parasite-infected dragonflies suffer the same metabolic disorders that have led to an epidemic of obesity and type-2 diabetes in humans, reveal the findings of research conducted at Penn State University that are due would be reported in the 5 December 2006 issue of the Proceedings of the National Academy of Science and also in the PNAS early online edition at www.pnas.org on 21 November. The discovery expands the known taxonomic breadth of metabolic disease and suggests that the study of microbes found in human intestines may provide a greater understanding of the root causes of human metabolic dysfunction.

James Marden, professor of biology and an insect physiologist at Penn State, and Ruud Schilder, who in August 2006 earned his doctorate in biology at Penn State and is now a postdoctoral fellow at the University of Nebraska, are the first to show a non-mammalian species suffering from metabolic dysfunction in ways similar to humans. "Metabolic disease isn't some strange thing having just to do with humans," said Marden. "Animals in general suffer from these symptoms".

The work is also novel because it links metabolic disease to a supposedly harmless parasite living in the dragonfly's gut. The parasites, known as gregarines, belong to the Apicomplexa, a group of microorganisms that includes protozoa, which cause diseases like malaria and cryptosporidiosis. The dragonfly species that Marden and Schilder studied is Libellula pulchella. The microbes disrupting the dragonfly metabolism may hold clues for researchers looking for the root causes of metabolic diseases in humans, as per Marden and Schilder's paper.........

Posted by: Beverly      Permalink         Source

November 20, 2006, 5:17 AM CT

Origins of Life

The origin of life lies in unique ocean reefs, and researchers from the University of Miami's Rosenstiel School of Marine & Atmospheric Science have developed an approach to help investigate them better. A new article reported in the recent issue of Geology reveals how Dr. Miriam Andres' stromatolite investigation - the first of its kind - has begun to "fingerprint" ancient microbial pathways, increasing the understanding of how these reef-like structures form and offering a new way to explore the origins of these living records, which are considered to be the core of most living organisms.

Modern marine stromatolites are living examples of one of the earth's oldest and most persistent widespread ecosystems. Eventhough rare today, these layered deposits of calcium carbonate are found in shallow marine seas throughout 3.4 billion-year-old geologic records. Ancient stromatolites represent a mineral record of carbonate chemistry and the evolution of early life. In the Geology paper, Dr. Andres and his colleagues point out that incorrect assumptions have been made in interpreting stromatolite data: phototrophs, or oxygen-producers, were actually dominated by heterotrophs, or oxygen-consumers, in their contribution to stromatolite formation.

"The motivation for this study is that in ancient stromatolites, direct evidence of microbial activity is lacking," Dr. Andres explained. "Stable isotopes have provided a powerful tool to 'fingerprint' microbial pathways and better understand the sedimentary structures we see in the geologic record. Surprisingly, no study to date has documented this process for modern marine stromatolites".........

Posted by: Beverly      Permalink         Source

November 19, 2006, 8:57 PM CT

Fighting Like A Girl Or Boy

Fighting like a girl or fighting like a boy is hardwired into fruit fly neurons, according to a study in the Nov. 19 Nature Neuroscience advance online publication by a research team from Harvard Medical School and the Institute of Molecular Pathology in Vienna. The results confirm that a gene known as "fruitless" is a key factor underlying sexual differences in behavior. The findings mark a milestone in an unlikely new animal model for understanding the biology of aggression and how the nervous system gives rise to different behaviors.

"Aggression is a very serious problem in society, and it's a problem with a biological and genetic component," said co-author Edward Kravitz, the George Packer Berry professor of neurobiology at HMS, who developed the fruit fly fighting model used. "We want to understand that. I can't think of a better system to study than fruit flies. And no one gets hurt".

The fruitless gene is known for its role in male courtship. The large gene makes a set of male-specific proteins found exclusively in the nervous system of fruit flies, in about 2 percent of neurons. The proteins are necessary for normal courting. Males missing the proteins do not court females, and they sometimes court males, other research groups have shown. Females with a male version of the gene perform the male courting ritual with other females.........

Posted by: Beverly      Permalink         Source

November 16, 2006, 9:55 PM CT

Emperor Penguin Physiology

Long before they lit up movie screens in animated feature films or enthralled documentary film audiences worldwide with the story of their endless struggle to survive and reproduce, Emperor penguins intrigued early Antarctic explorers.

As movie makers prepare this weekend to release "Happy Feet," about an animated Emperor who loves to dance, and the Hallmark Channel readies the cable-television premier of the documentary "March of the Penguins" on Sat., Nov. 25, 2006, the National Science Foundation (NSF) is making available B-roll of the penguins in Antarctica. The agency is also offering journalists the opportunity to ask Antarctic scientists questions about why the birds still challenge the scientific mind.

On the eve of International Polar Year (IPY), Emperor penguins, which can dive unharmed to depths that no human could survive unaided, still fascinate researchers.

By studying the animals' physiology and the way their bodies respond to the crushing pressure of deep dives, these NSF-funded scientists, who also are medical doctors, may one day provide clues to help improve surgical procedures and anesthesia. The study of Emperors also is very much in the spirit of NSF's IPY theme of attempting to understand what makes the processes of life in the cold and dark unique.........

Posted by: Beverly      Permalink         Source

November 16, 2006, 9:48 PM CT

Different Coat Color doesn't Mean Different Species

Researchers have found that lemurs suspected to belong to different species because of their strikingly different coat colors, are not only genetically alike, but belong to the same species.

Historically, species classification has been based on comparison of visible physical characteristics of plants or animals. Kellie Heckman, a post-doctoral fellow in ecology and evolutionary biology at Yale, and her colleagues at other universities, used analysis of a mitochondrial gene, cytochrome b, to test the genetic relationship of 70 lemurs that were thought to belong to up to three different species. Their report was published in the open access journal BMC Evolutionary Biology.

"Our study combined morphological, genetic, geographic, and ecological data giving a multidimensional, and hopefully more accurate picture of species diversity," said Heckman. "Over the past decade, the number of proposed species of these lemurs has jumped from two to fifteen, based on physical differences. It pointed to the need for caution when identifying new species solely on the basis of visual or genetic characteristics".

The lemurs they tested had three extremely different coat colors and lived in different types of forest locations in southern Madagascar - classic characteristics of separate species. These researchers chose to compare mitochondrial cytochrome b as a gene marker that is known to change at a rate similar to that of speciation. Other common nuclear genes may evolve more slowly or more rapidly with population drift.........

Posted by: Beverly      Permalink         Source

November 16, 2006, 9:27 PM CT

Edible Food Wrap Kills Deadly E. Coli

Scientists have improved upon an edible coating for fresh fruits and vegetables by enabling it to kill deadly E. coli bacteria while also providing a flavor-boost to food. Composed of apple puree and oregano oil, which acts as a natural antibacterial agent, the coating shows promise in laboratory studies of becoming a long-lasting, potent alternative to conventional produce washes, as per a team of researchers from the U.S. Department of Agriculture (USDA) and the University of Lleida in Spain.

The study comes on the heels of the recent deadly E. coli outbreak in spinach and amid growing concern by experts that some produce-cleaning techniques may not be effective in destroying E. coli. The study is scheduled for the Nov. 29 issue of the American Chemical Society's Journal of Agricultural and Food Chemistry.

"All produce-cleaning methods help to some degree, but our new coatings and films may provide a more concentrated, longer-lasting method for killing bacteria," says Research Leader Tara H. McHugh, Ph.D., a food chemist with the USDA's Agricultural Research Service in Albany, Calif. As the films are made of fruit or vegetable puree, they also provide added health benefits such as vitamins, minerals and antioxidants, she says.

Scientists have known about the antimicrobial activity of plant-derived essential oils for some time, but McHugh says that her group is the first to incorporate them into a fruit- or vegetable-based edible food wrap for the purpose of improving food safety. Three years ago, she and her associates developed a similar edible food wrap, but without the antimicrobial properties.........

Posted by: Ethen      Permalink         Source

November 16, 2006, 4:59 AM CT

Key To Controlling Gypsy Moth Spread

Controlling population peaks on the edges of the gypsy moth range may help to slow their invasion into virgin territory, according to a team of researchers.

"Slowing the spread of the gypsy moth is a priority in forest management in the U.S.," says Ottar Bjornstad, associate professor of entomology and biology, Penn State. "Understanding the underlying patterns in the spread of invasive species is important for successful management".

The accidental release of the gypsy moth in 1869 in Massachusetts has led to an infestation covering more than 386,000 square miles of the U.S. Northeast. Native to Europe and Asia, gypsy moths are currently found from Maine to North Carolina and west into Wisconsin where they defoliate trees and occasionally, cause extensive damage to northern deciduous forests.

"We analyzed historical data on the spread of the gypsy moth in the U.S. and found that its invasion has been characterized by regular periods of rapid spread interspersed between periods of little expansion," says Bjornstad. "This is the first identification of pulsed invasions for an invading species".

Bjornstad; Derek M. Johnson, Department of Biology, University of Louisiana, and Andrew M. Liebhold and Patrick C. Tobin, U.S. Forest Service, used historical, county-level quarantine records as well as forest service data from more than 100,000 pheromone traps set along the expanding gypsy moth population front for their theoretical model. The pheromone trap data were collected from 1988 to 2004.........

Posted by: Beverly      Permalink         Source

November 16, 2006, 4:35 AM CT

Relativistic Pinball Machine

New clues about the origins of cosmic rays, mysterious high-energy particles that bombard the Earth, have been revealed using NASA's Chandra X-ray Observatory. An extraordinarily detailed image of the remains of an exploded star provides crucial insight into the generation of cosmic rays.

For the first time, astronomers have mapped the rate of acceleration of cosmic ray electrons in a supernova remnant. The new map shows that the electrons are being accelerated at close to the theoretically maximum rate. This discovery provides compelling evidence that supernova remnants are key sites for energizing charged particles.

The map was created from an image of Cassiopeia A, a 325-year-old remnant produced by the explosive death of a massive star. The blue, wispy arcs in the image trace the expanding outer shock wave where the acceleration takes place. The other colors in the image show debris from the explosion that has been heated to millions of degrees.

"Researchers have theorized since the 1960s that cosmic rays must be created in the tangle of magnetic fields at the shock, but here we can see this happening directly," said Michael Stage of the University of Massachusetts, Amherst. "Explaining where cosmic rays come from helps us to understand other mysterious phenomena in the high-energy universe".........

Posted by: Beverly      Permalink         Source