September 24, 2007, 10:08 PM CT

Extraterrestrial impact to blame for Ice Age extinctions

What caused the extinction of mammoths and the decline of Stone Age people about 13,000 years ago remains hotly debated. Overhunting by Paleoindians, climate change and disease lead the list of probable causes. But an idea once considered a little out there is now hitting closer to home.

A team of international researchers, including two Northern Arizona University geologists, reports evidence that a comet or low-density object barreling toward Earth exploded in the upper atmosphere and triggered a devastating swath of destruction that wiped out most of the large animals, their habitat and humans of that period.

The detonation either fried them or compressed them because of the shock wave, said Ted Bunch, NAU adjunct professor of geology and former NASA researcher who specializes in impact craters. It was a mini nuclear winter.

Bunch and Jim Wittke, a geologic materials analyst at NAU, are co-authors of the paper, which fingers an extraterrestrial impact 12,900 years ago for the mass extinctions at the end of the Ice Age. The paper was just released online in the Proceedings of the National Academy of Sciences. The research team includes several members of the U.S. National Academy of Sciences and scientists from Hungary and the Netherlands.

No one has found a giant crater in the Earth that could attest to such a cataclysmic impact 13,000 years ago, but the research team offers evidence of a comet, two and a half to three miles in diameter, that detonated 30 to 60 miles above the earth, triggering a massive shockwave, firestorms and a subsequent drastic cooling effect across most of North America and northern Europe......... Posted by: William      Read more         Source

September 23, 2007, 11:47 AM CT

Greeks get space-based help

Cleanup and rebuilding teams responding to the devastation across Greece caused by this summer's deadly fires are getting help from space. A series of crisis map products based on satellite acquisitions of affected areas are being provided to aid damage assessment efforts following the activation of the International Charter on Space and Major Disasters.

More than 60 people were killed and thousands left homeless in the worst forest fires to hit Greece in decades. As per data from ESA's ERS-2 and Envisat satellites, which continuously survey fires burning across the Earth's surface with onboard sensors, Greece experienced more wildfire activity this August than other European countries experienced over the last decade.

In an effort to aid authorities responding to disasters such as this, ESA and other national space agencies established the International Charter on Space and Major Disasters in 2000 to provide rush access to a broad range of satellite data.

The Charter, activated by the Department of Emergency Planning and Response of the Greek Civil Protection Agency, processed this request and recruited the German Aerospace Centre (DLR) and the Strasbourg-based rapid mapping specialist company (SERTIT) to produce the maps using satellite images provided by the space agencies......... Posted by: Tyler      Read more         Source

September 23, 2007, 11:39 AM CT

A better definition for the kilogram?

How much is a kilogram?.

It turns out that nobody can say for sure, at least not in a way that wont change ever so slightly over time. The official kilogram a cylinder cast 118 years ago from platinum and iridium and known as the International Prototype Kilogram or Le Gran K has been losing mass, about 50 micrograms at last check. The change is occurring despite careful storage at a facility near Paris.

Thats not so good for a standard the world depends on to define mass.

Now, two U.S. professors a physicist and mathematician say its time to define the kilogram in a new and more elegant way that will be the same today, tomorrow and 118 years from now. Theyve launched a campaign aimed at redefining the kilogram as the mass of a very large but precisely-specified number of carbon-12 atoms.

Our standard would eliminate the need for a physical artifact to define what a kilogram is, said Ronald F. Fox, a Regents Professor Emeritus in the School of Physics at the Georgia Institute of Technology. We want something that is logically very simple to understand.

Their proposal is that the gram 1/1000th of a kilogram would henceforth be defined as the mass of exactly 18 x 14074481 (cubed) carbon-12 atoms.

The proposal, made by Fox and Theodore P. Hill a Professor Emeritus in the Georgia Tech School of Mathematics first assigns a specific value to Avogadros constant. Proposed in the 1800s by Italian scientist Amedeo Avogadro, the constant represents the number of atoms or molecules in one mole of a pure material for instance, the number of carbon-12 atoms in 12 grams of the element. However, Avogadros constant isnt a specific number; its a range of values that can be determined experimentally, but not with enough precision to be a single number......... Posted by: Sarah      Read more         Source

September 23, 2007, 10:44 AM CT

Palladium and platinum an easier find

Finding uses for palladium and platinum--rare precious metals coveted by the automobile, chemical, and pharmaceutical industries as catalysts in chemical reactions-proves easier than finding the scarce materials themselves.

Detection involves expensive instruments operated by highly trained chemists that take days to return results. But chemists at the University of Pittsburgh have unearthed a fast, easy, and inexpensive method that could help in the discovery of palladium/platinum deposits and streamline the production of pharmaceuticals. The research will be published online Sept. 21 in the Journal of the American Chemical Society.

The new method was developed in the laboratory of Kazunori Koide (Ko-ee-deh), a chemistry professor in Pitt's School of Arts and Sciences. It relies on a colorless fluorescein-based solution (similar to that used to find blood residue at crime scenes) that--under a simple hand-held ultraviolet lamp--glows green when it comes in contact with even minute amounts of palladium and platinum, which coexist in nature. The process takes approximately one hour as opposed to the effective but complex and days-long analysis currently employed in the mining and pharmaceutical industries, Koide explained. Moreover, the Pitt team's method can accommodate hundreds of samples at once whereas current technology analyzes samples only one at a time, Koide said......... Posted by: Sarah      Read more         Source

September 21, 2007, 6:42 AM CT

Studying Volatile Earthquake Zone

Today, the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) gets underway, with the Japanese drilling vessel Chikyu departing from Shingu Port with researchers aboard, all ready to log, drill, sample, and install monitoring instrumentation in one of the most active earthquake zones on Earth. The vessel's launch starts the first of a series of scientific drilling expeditions that will retrieve geological samples and provide scientific data from the Nankai Trough fault zone for the first time. Situated off Japan's southwest coast, the Nankai Trough has reliably generated large-scale earthquakes and tsunamis for millions of years, including historic earthquakes in 1944 and 1946, which measured 8.1 and 8.3, respectively, on the Richter scale. The NanTroSEIZE expeditions are supported by the Integrated Ocean Drilling Program, a marine research initiative jointly funded by Japan, the United States, a consortium of European countries, the People's Republic of China, and South Korea.

NanTroSEIZE researchers are prepared to drill deeply into the Earth to observe earthquake mechanisms in a well-known subduction zone. The process of subduction occurs when tectonic plates collide and one plate slides beneath another. Geological samples will be collected from the subduction zone, so that IODP researchers can analyze them and study the frictional properties of the rock. Later, sensors are to be installed deep beneath the sea floor- in the seismogenic fault zone-to monitor development of earthquakes at close range. These sensors and data collected from cored samples are expected to yield new insights into naturally occurring processes responsible for earthquakes. IODP researchers anticipate that the new data also will help them understand water motion and how water affects subduction zones......... Posted by: Tyler      Read more         Source

September 21, 2007, 6:35 AM CT

Human ancestors more primitive that once thought

A team of researchers, including Herman Pontzer, Ph.D., assistant professor of physical anthropology in Arts & Sciences, has determined through analysis of the earliest known hominid fossils outside of Africa, recently discovered in Dmanisi, Georgia, the former Soviet republic, that the first human ancestors to inhabit Eurasia were more primitive than previously thought.

The fossils, dated to 1.8 million years old, show some modern aspects of lower limb morphology, such as long legs and an arched foot, but retain some primitive aspects of morphology in the shoulder and foot. The species had a small stature and brain size more similar to earlier species found in Africa.

"Thus, the earliest known hominins to have lived outside Africa in temperate zones of Eurasia did still not display the full set of derived skeletal features," the scientists conclude.

The findings, published Sept. 20 in the journal "Nature," are a marked step in learning more about the first human ancestors to migrate from Africa.

The lead author of the paper is David Lordpkipanidze, director of the National Museum of Georgia. Collaborators on the study include Pontzer and scientists from Georgia, Switzerland, Italy and Spain.

The new evidence shows how this species had the anatomical and behavioral capacity to be successful across a range of environments and expand out of Africa, said Pontzer, who studies how the musculoskeletal anatomy of an animal reflect its performance, ecological niche and evolutionary history......... Posted by: William      Read more         Source

September 21, 2007, 5:27 AM CT

Arctic sea ice minimum shatters all-time record low

Researchers from the University of Colorado at Boulder's National Snow and Ice Data Center said today that the extent of Arctic sea ice appears to have reached its minimum for 2007 on Sept. 16, shattering all prior lows since satellite record-keeping began nearly 30 years ago.

The Arctic sea ice extent on Sept. 16 stood at 1.59 million square miles, or 4.13 million square kilometers, as calculated using a five-day running average, as per the team. In comparison to the long-term minimum average from 1979 to 2000, the new minimum extent was lower by about 1 million square miles -- an area about the size of Alaska and Texas combined, or 10 United Kingdoms, they reported.

The minimum also breaks the prior minimum set on Sept. 20 and Sept. 21 of 2005 by about 460,000 square miles, an area roughly the size of Texas and California combined, or five United Kingdoms, they found. The sea ice extent is the total area of all Arctic regions where ice covers at least 15 percent of the ocean surface.

Researchers blame the declining Arctic sea ice on rising concentrations of greenhouse gases that have elevated temperatures from 2 degrees F to 7 degrees F across the arctic and strong natural variability in Arctic sea ice, said the researchers.

The CU-Boulder research group said determining the annual minimum sea ice is difficult until the melt season has decisively ended. But the team has recorded five days of little change, and even slight gains in Arctic sea ice extent this September, so reaching a lower minimum for 2007 seems unlikely, they reported......... Posted by: Tyler      Read more         Source

September 21, 2007, 5:22 AM CT

Computer program traces ancestry

A group of computer scientists, mathematicians, and biologists from around the world have developed a computer algorithm that can help trace the genetic ancestry of thousands of individuals in minutes, without any previous knowledge of their background. The teams findings would be reported in the September 2007 edition of the journal PLoS Genetics.

Unlike prior computer programs of its kind that require previous knowledge of an individuals ancestry and background, this new algorithm looks for specific DNA markers known as single nucleotide polymorphisms, or SNPs (pronounced snips), and needs nothing more than a DNA sample in the form of a simple cheek swab. The scientists used genetic data from prior studies to perform and confirm their research, including the new HapMap database, which is working to uncover and map variations in the human genome.

Now that we have observed that the program works well, we hope to implement it on a much larger scale, using hundreds of thousands of SNPs and thousands of individuals, said Petros Drineas, the senior author of the study and assistant professor of computer science at Rensselaer Polytechnic Institute. The program will be a valuable tool for understanding our genetic ancestry and targeting drugs and other medical therapys because it might be possible that these can affect people of different ancestry in very different ways......... Posted by: Kevin      Read more         Source

September 18, 2007, 5:33 AM CT

Satellites witness lowest Arctic ice coverage in history

The area covered by sea ice in the Arctic has shrunk to its lowest level this week since satellite measurements began nearly 30 years ago, opening up the Northwest Passage - a long-sought short cut between Europe and Asia that has been historically impassable.

In the mosaic image above, created from nearly 200 images acquired in early September 2007 by the Advanced Synthetic Aperture Radar (ASAR) instrument aboard ESA's Envisat satellite, the dark gray colour represents the ice-free areas while green represents areas with sea ice.

Leif Toudal Pedersen from the Danish National Space Centre said: "We have seen the ice-covered area drop to just around 3 million sq km which is about 1 million sq km less than the prior minima of 2005 and 2006. There has been a reduction of the ice cover over the last 10 years of about 100 000 sq km per year on average, so a drop of 1 million sq km in just one year is extreme.

"The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected and that we urgently need to understand better the processes involved."

Arctic sea ice naturally extends its surface coverage each northern winter and recedes each northern summer, but the rate of overall loss since 1978 when satellite records began has accelerated......... Posted by: Tyler      Read more         Source

September 18, 2007, 5:01 AM CT

Changing concepts on neutron's electrical properties

For two generations of physicists, it has been a standard belief that the neutron, an electrically neutral elementary particle and a primary component of an atom, actually carries a positive charge at its center and an offsetting negative charge at its outer edge.

The notion was first put forth in 1947 by Enrico Fermi, a Nobel laureate noted for his role in developing the first nuclear reactor. But new research by a University of Washington physicist shows the neutron's charge is not quite as simple as Fermi believed.

Using precise data recently gathered at three different laboratories and some new theoretical tools, Gerald A. Miller, a UW physics professor, has observed that the neutron has a negative charge both in its inner core and its outer edge, with a positive charge sandwiched in between to make the particle electrically neutral.

"Nobody realized this was the case," Miller said. "It is significant because it is a clear fact of nature that we didn't know before. Now we know it".

The discovery changes scientific understanding of how neutrons interact with negatively charged electrons and positively charged protons. Specifically, it has implications for understanding the strong force, one of the four fundamental forces of nature (the others are the weak force, electromagnetism and gravity)......... Posted by: Sarah      Read more         Source