January 21, 2008, 9:22 PM CT

First evidence of under-ice volcanic eruption

The first evidence of a volcanic eruption from beneath Antarcticas most rapidly changing ice sheet is reported this week in the journal Nature Geosciences. The volcano on the West Antarctic Ice Sheet erupted 2000 years ago (325BC) and remains active.

Using airborne ice-sounding radar, researchers from British Antarctic Survey (BAS) discovered a layer of ash produced by a subglacial volcano. It extends across an area larger than Wales.

Lead author, Hugh Corr of the BAS says,.

The discovery of a subglacial volcanic eruption from beneath the Antarctic ice sheet is unique in itself. But our techniques also allow us to put a date on the eruption, determine how powerful it was and map out the area where ash fell. We believe this was the biggest eruption in Antarctica during the last 10,000 years. It blew a substantial hole in the ice sheet, and generated a plume of ash and gas that rose around 12 km into air.

The discovery is another vital piece of evidence that will help determine the future of the West Antarctic Ice Sheet and refine predictions of future sea-level rise. Co-author Professor David Vaughan (BAS) says,.

This eruption occurred close to Pine Island Glacier on the West Antarctic Ice Sheet. The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters......... Posted by: Tyler      Read more         Source

January 17, 2008, 9:09 PM CT

Winter Ice on Lakes: A Thing of the Past?

If you're planning to ice skate on a local lake or river this winter, you may need to think twice, as per researchers John Magnuson, Olaf Jensen and Barbara Benson of the University of Wisconsin at Madison. Their research is funded by the National Science Foundation (NSF).

From sources as diverse as newspaper archives, transportation ledgers and religious observances, the scientists have amassed 150 years of lake and river ice records spanning the Northern Hemisphere. All show a steady trend of fewer days of ice cover.

If the pattern continues, only in Currier and Ives prints will ice skaters twirl across frozen rivers.

The records show that later freezing and earlier ice breakup occurred on lakes and rivers across the Northern Hemisphere from 1846 to 1995. Over those 150 years, said Magnuson, changes in freeze dates averaged 5.8 days per 100 years later, and changes in ice breakup dates averaged 6.5 days per 100 years earlier. The findings translate to increasing air temperatures of about 1.2 degrees Celsius each century.

Now the researchers have looked more specifically at trends in ice duration in 65 waterbodies across what might be called the last bastion of winter in the U.S.--the Great Lakes region (Minnesota, Wisconsin, Michigan, Ontario and New York)--during a period of rapid climate warming (1975-2004)......... Posted by: Tyler      Read more         Source

January 17, 2008, 9:00 PM CT

Quakes Under Pacific Ocean Floor

Zigzagging some 60,000 kilometers across the ocean floor, Earth's system of mid-ocean ridges plays a pivotal role in a number of workings of the planet: in plate-tectonic movements, heat flow from the interior, and the chemistry of rock, water and air.

Now, a team of seismologists working in 2,500 meters of water on the East Pacific Rise, some 565 miles southwest of Acapulco, Mexico, has made the first images of one of these systems--and it doesn't look the way most researchers had assumed. The research results, funded by the National Science Foundation (NSF), appear in this week's issue of the journal Nature.

It was not until the late 1970s that researchers discovered the existence of vast plumbing systems under the oceans called hydrothermal vents. The systems pull in cold water, superheat it, then spit it back out from seafloor vents--a process that brings up not only hot water, but dissolved substances from rocks below. Unique life forms feed off the vents' stew, and valuable minerals including gold may pile up.

The hypothetical image of a hydrothermal-vent system shows water forced down by overlying pressure through large faults along ridge flanks. The water is heated by shallow volcanism, then rises toward the ridges' middles, where vents (often called "black smokers," for the cloud of chemicals they exude) tend to cluster......... Posted by: Tyler      Read more         Source

January 14, 2008, 5:35 PM CT

T.-rex had teen pregnancies

Dinosaurs had pregnancies as early as age 8, far before they reached their maximum adult size, a new study finds.

Scientists at Ohio University and University of California at Berkeley have found medullary bone the same tissue that allows birds to develop eggshells in two new dinosaur specimens: the meat-eater Allosaurus and the plant-eater Tenontosaurus. Its also been found in Tyrannosaurus rex.

The discovery allowed scientists to pinpoint the age of these pregnant dinosaurs, which were 8, 10 and 18. That suggests that the creatures reached sexual maturity earlier than previously thought, as per the scientists, who will publish their study Jan. 15 in the journal Proceedings of the National Academy of Sciences.

The researchers originally studied the bones, which come from different geologic periods, to learn more about dinosaur growth rates. Because scientists rarely find fossils of adult dinosaurs, some have speculated that the ancient beasts never stopped developing, said Andrew Lee, a postdoctoral student at the Ohio University College of Osteopathic Medicine who conducted the work as a graduate student at University of California at Berkeley with scientist Sarah Werning.

The new study suggests another explanation: Dinosaurs grew fast but only lived three to four years in adulthood. Offspring were probably precocious, like calves or foals, Lee said......... Posted by: William      Read more         Source

January 14, 2008, 4:25 PM CT

From the Journal of Biological Chemistry

COX-2 inhibitors like Celecoxib have come under scrutiny lately due to adverse cardiovascular side-effects stemming from COX-2 reduction. In both fruit fly and rat models, scientists reveal another adverse effect of Celecoxib; this drug can induce arrhythmia. More interestingly, this effect is independent of the COX-2 enzyme.

Satpal Singh and his colleagues tested various Celecoxib doses on the heart rate of Drosophila, a good model for human cardiac pharmacology. To their surprise, administering 3 m Celecoxib (not much higher than the plasma levels in humans taking the drug) reduced heart rate and increased beating irregularities, while 30 m was enough to stop the heart within a minute.

The surprise arises from the fact that Drosophila do not have COX-2 enzymes. Rather, Celecoxib could directly inhibit the potassium channels that help generate the electric current that drives heartbeat.

The scientists could achieve similar heart-stopping results in rat cardiac cells, whereas aspirin, another potent COX-2 inhibitor, had no effect, confirming that another mechanism is at work. The drug also inhibited rat and human potassium channels expressed in a human cell line.

Singh and his colleagues point out that since these arrhythmia effects bypass COX-2, it is unclear if other COX-2 inhibitors would yield similar results. They also stress it is too early to speculate on human effects, eventhough their results suggest Drosophila are a valuable tool to investigate other COX-2 drugs......... Posted by: Sarah      Read more         Source

January 14, 2008, 3:39 PM CT

New buffer resists pH change

Scientists at the University of Illinois have found a simple solution to a problem that has plagued researchers for decades: the tendency of chemical buffers used to maintain the pH of laboratory samples to lose their efficacy as the samples are cooled. The research team, headed by chemistry professor Yi Lu, developed a method to formulate a buffer that maintains a desired pH at a range of low temperatures.

The study appears this month in Chemical Communications.

Researchers have known since the 1930s that the pH of chemical buffers that are used to maintain the pH of lab samples can change as those samples are cooled, with some buffers raising and others lowering pH in the cooling process.

Freezing is a standard method for extending the shelf life of biological specimens and pharmaceuticals, and biological samples are routinely cooled to slow chemical reactions in some experiments. Even tiny changes in the acidity or alkalinity of a sample can influence its properties, Lu said.

"We like to freeze proteins, nucleic acids, pharmaceutical drugs and other biomolecules to keep them a long time and to study them more readily under very low temperatures using different spectroscopic techniques and X-ray crystallography," Lu said. "But when the pH changes at low temperature, the sample integrity can change"......... Posted by: Sarah      Read more         Source

January 14, 2008, 3:24 PM CT

Effects of global change on Mackenzie River Delta

River delta regions along the Arctic coast are poorly understood ecosystems that are expected to change rapidly as the climate warms, sea levels rise, and seasonal river ice jams become less frequent. In northern Canada's Mackenzie River Delta, flood pulses driven by ice breakup control the degree to which river water moves off-channel to replenish nearby lakes, which only exist because of such river dynamics.

Lesack and Marsh analyze more than 30 years of data on the Mackenzie Delta and find that the duration of river-to-lake connection has lengthened on average more than 30 days since the 1970s. Further, the duration of river-to-lake connection has shortened in the highest elevation lakes, likely owing to the declining effects of river-ice breakup. The authors conclude that not only are the higher elevation lakes at risk of drying up from declining water level peaks, but lower elevation lakes now contain more water than can be accounted for through sea level rise, suggesting that increasing storm surge intensity, permafrost melting, or backwater flow might play an unexpected role......... Posted by: Tyler      Read more         Source

January 14, 2008, 3:19 PM CT

Pulses in Saturn's rings

In 2005, the Cassini spacecraft began a series of experiments to profile ring structure and measure the size distribution of particles in Saturn's rings. During these experiments, Cassini flew behind the ring plane and transmitted radio waves through ring particles to Earth. Researchers on Earth analyzed the signals' diffraction patterns to help determine properties of the rings. Thomson et al.

Typically study these data and find that in limited regions of rings a and b (a and b lie close to the outside of saturn's ring system), the diffraction pattern reveals the presence of fine-scale structures that are characterized by periodic radial variation in optical depth. They define specific periods of variation in optical depth for distinct regions of rings A and B. Past research suggests that the dynamic interplay of gravitational and collisional forces leads to the formation of viscous oscillations and gravity wakes in Saturn's rings. The authors speculate that the number density of ring particles contracts and relaxes to form periodic structures that affect the radio signals seen on Earth......... Posted by: Brooke      Read more         Source

January 10, 2008, 10:58 PM CT

A warming climate can support glacial ice

New research challenges the generally accepted belief that substantial ice sheets could not have existed on Earth during past super-warm climate events. The study by scientists at Scripps Institution of Oceanography at UC San Diego provides good evidence that a glacial ice cap, about half the size of the modern day glacial ice sheet, existed 91 million years ago during a period of intense global warming. This study offers valuable insight into current day climate conditions and the environmental mechanisms for global sea level rise.

The new study in the Jan. 11 issue of the journal Science titled, Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse, examines geochemical and sea level data retrieved from marine microfossils deposited on the ocean floor 91 million years ago during the Cretaceous Thermal Maximum. This extreme warming event in Earths history raised tropical ocean temperatures to 35-37C (95-98.6F), about 10C (50F) warmer than today, thus creating an intense greenhouse climate.

Using two independent isotopic techniques, scientists at Scripps Oceanography studied the microfossils to gather geochemical data on the growth and eventual melting of large Cretaceous ice sheets. The scientists compared stable isotopes of oxygen molecules (d18O) in bottom-dwelling and near-surface marine microfossils, known as foraminifera, to show that changes in ocean chemistry were consistent with the growth of an ice sheet. The second method in which an ocean surface temperature record was subtracted from the stable isotope record of surface ocean microfossils yielded the same conclusion......... Posted by: Tyler      Read more         Source

January 10, 2008, 10:50 PM CT

Fighting pollution the poplar way

Purdue University scientists are collaborating with Chrysler LLC in a project to use poplar trees to eliminate pollutants from a contaminated site in north-central Indiana.

The scientists plan to plant transgenic poplars at the site, a former oil storage facility near Kokomo, Ind., this summer. In a laboratory setting, the transgenic trees have been shown to be capable of absorbing trichloroethylene, or TCE, and other pollutants before processing them into harmless byproducts.

Richard Meilan, a Purdue associate professor, is currently at work to transform one variety of poplar suited to Indiana's climate; cold-hardy poplars are generally more difficult to alter than the variety used in a laboratory setting.

"This site presents the perfect opportunity to prove that poplars can get rid of pollution in the real world," Meilan said.

In a study Meilan co-authored, published last October in Proceedings of the National Academy of Sciences, poplar cuttings removed 90 percent of the TCE within a hydroponic solution in one week. The engineered trees also took up and metabolized the chemical 100 times faster than unaltered hybrid poplars, which have a limited ability to remove and degrade the contaminant on their own, he said.

The transgenic poplars contain an inserted gene that encodes an enzyme capable of breaking down TCE and a variety of other environmental pollutants, including chloroform, benzene, vinyl chloride and carbon tetrachloride......... Posted by: Tyler      Read more         Source