April 16, 2007, 10:13 PM CT

Was Einstein right?

For the past three years a satellite has circled the Earth, collecting data to determine whether two predictions of Albert Einstein's general theory of relativity are correct. Today, at the American Physical Society (APS) meeting in Jacksonville, Fla., Professor Francis Everitt, a Stanford University physicist and principal investigator of the Gravity Probe B (GP-B) Relativity Mission, a collaboration of Stanford, NASA and Lockheed Martin, will provide the first public peek at data that will reveal whether Einstein's theory has been confirmed by the most sophisticated orbiting laboratory ever created.

"Gravity Probe B has been a great scientific adventure for all of us, and we are grateful to NASA for its long history of support," Everitt said. "My colleagues and I will be presenting the first results today and tomorrow. It's fascinating to be able to watch the Einstein warping of space-time directly in the tilting of these GP-B gyroscopes-more than a million times better than the best inertial navigation gyroscopes."

The GP-B satellite was launched in April 2004. It collected more than a year's worth of data that the Stanford GP-B science team has been poring over for the past 18 months. The satellite was designed as a pristine, space-borne laboratory, whose sole task was to use four ultra-precise gyroscopes to measure directly two effects predicted by general relativity. One is the geodetic effect-the amount by which the mass of the Earth warps the local space-time in which it resides. The other effect, called frame-dragging, is the amount by which the rotating Earth drags local space-time around with it. As per Einstein's theory, over the course of a year, the geodetic warping of Earth's local space-time causes the spin axes of each gyroscope to shift from its initial alignment by a minuscule angle of 6.606 arc-seconds (0.0018 degrees) in the plane of the spacecraft's orbit. Likewise, the twisting of Earth's local space-time causes the spin axis to shift by an even smaller angle of 0.039 arc-seconds (0.000011 degrees)-about the width of a human hair viewed from a quarter mile away-in the plane of the Earth's equator......... Posted by: Sarah      Read more         Source

April 16, 2007, 8:37 PM CT

Examining Arctic Changes from Under the Ice

Scientists from the Woods Hole Oceanographic Institution (WHOI) are venturing this month to the North Pole to deploy instruments that will make year-round observations of the water beneath the Arctic ice cap. Researchers will investigate how the waters in the upper layers of the Arctic Ocean-which insulate surface ice from warmer, deeper waters-are changing from season to season and year to year as global climate fluctuates.

The Arctic expedition is part of a multi-year, multi-institutional program to establish a real-time, autonomous Arctic Observing Network. The WHOI scientists will work out of the North Pole Environmental Observatory, a yearly research camp on the ice that is organized and led by the University of Washington's Polar Science Center.

Arctic research specialist Rick Krishfield and engineering assistant Kris Newhall will lead the WHOI expedition this spring, deploying two autonomous ice-based observatories between 88 degree and 90 degree North. The observatories are similar in design to moored, open-ocean buoys, though they will be anchored to the ice instead of the seafloor. The instruments will slowly drift with the natural movement of the ice while observing water properties in the top 800 meters of the Arctic Ocean. The buoys are designed to last three years, about the same lifespan as the ice floes that support them......... Posted by: Tyler      Read more         Source

April 15, 2007, 9:11 PM CT

Efforts To Develop A Melanoma Vaccine

In recent years, researchers have worked to develop a number of vaccines to help the immune system fight tumors. Cancer vaccines are not intended to prevent cancer; rather, they are used to boost immune responses to preexisting tumors. Unlike traditional chemotherapy, vaccines have relatively low toxicity and, potentially, a high degree of efficacy.

To date, these vaccines have rarely been designed to directly stimulate one of the body's most critical immune responders, the helper T cells. Though helper T cells contain receptors on their cell surfaces that are capable of recognizing and binding to tumor-related antigens, scientists have been stymied by the complex and time-consuming process required to isolate and clone the antigens for vaccine development.

In working to identify a key tumor antigen in melanoma and other cancers, scientists at The Wistar Institute have now developed a novel way to clone an antigen recognized by a helper T cell. Already, Herlyn's group has used the new cloning technique to identify a new tumor antigen called ribosomal protein L8, or RPL8. Findings on the new cloning method and the newly identified tumor antigen will be published as a Priority Report in the April 15 issue of Cancer Research.

The new antigen-cloning approach may allow scientists to design vaccines capable of directly stimulating helper T cells, aiding the development of vaccines not only for cancer but also for infectious diseases, says Dorothee Herlyn, D.V.M., senior author on the study and a professor in the Molecular and Cellular Oncogenesis and Immunology programs at Wistar......... Posted by: Sean      Read more         Source

April 12, 2007, 6:46 PM CT

Forecasts Disappearance of Existing Climate Zones

new climate modeling study forecasts the complete disappearance of several existing climates in tropical highlands and regions near the poles, while large swaths of the tropics and subtropics may develop new climates unlike any seen today.

In general, the models show that existing climate zones will shift toward higher latitudes and higher elevations, squeezing out the climates at the extremes--tropical mountaintops and the poles--and leaving room for unfamiliar climes and new ecological niches around the equator.

The work, by scientists at the University of Wisconsin-Madison and the University of Wyoming, appears online in the journal Proceedings of the National Academy of Sciences (PNAS) during the week of March 26. The National Science Foundation (NSF) funded the research.

The most severely affected parts of the world span both heavily populated regions, including the southeastern United States, southeastern Asia, and parts of Africa, and known hotspots of biodiversity, such as the Amazonian rainforest and African and South American mountain ranges.

The patterns of change foreshadow significant impacts on ecosystems and conservation. "There is a close correspondence between disappearing climates and areas of biodiversity," says University of Wisconsin at Madison geographer Jack Williams, primary author of the paper, which could increase risk of extinction in the affected areas......... Posted by: Tyler      Read more         Source

April 12, 2007, 6:36 PM CT

Ancient T. rex and mastodon protein discovered

Researchers have confirmed the existence of protein in soft tissue recovered from the fossil bones of a 68 million-year-old Tyrannosaurus rex (T. rex) and a half-million-year-old mastodon.

Their results may change the way people think about fossil preservation and present a new method for studying diseases in which identification of proteins is important, such as cancer.

When an animal dies, protein immediately begins to degrade and, in the case of fossils, is slowly replaced by mineral. This substitution process was believed to be complete by 1 million years. Scientists at North Carolina State University (NCSU) and Harvard Medical School now know otherwise.

The researchers' findings appear as companion papers in this week's issue of the journal Science.

"Not only was protein detectably present in these fossils, the preserved material was in good enough condition that it could be identified," said Paul Filmer, program director in the National Science Foundation (NSF) Division of Earth Sciences, which funded the research. "We now know much more about what conditions proteins can survive in. It turns out that some proteins can survive for very long time periods, far longer than anyone predicted".

Mary Schweitzer of NCSU and the North Carolina Museum of Natural Sciences discovered soft tissue in the leg bone of a T. rex and other fossils recovered from the Hell Creek sediment formation in Montana......... Posted by: William      Read more         Source

April 12, 2007, 6:33 PM CT

Mass weddings: new efficient 2-photon source

For a variety of applications in physics and technology, ranging from quantum information theory to telecommunications, its handy to have access to pairs of photons created simultaneously, with a chosen energy. In a significant improvement on prior designs, physicists at the National Institute of Standards and Technology (NIST) have devised a system that delivers such pairs with great efficiency over a wide range of energy, and with very little noise from extraneous photons*.

Paired photons can be generatedalbeit very inefficientlyin standard optical media such as glass optical fibers. Photons normally travel through glass independently, without interacting, but if monochromatic laser light is sent down even an ordinary optical fiber, very occasionally two of the input photons will interact, producing an output photon pair with one higher in energy than the original photons and the other lower by the same amount.

Because the vast majority of photons go through the fiber unchanged, the relative intensity of these pairs is very small. Worse, the fiber generates the pairs randomly with a range of possible energies, so picking out those with some specific energy reduces the number of useful photon pairs still further. Worse yet, there is noise in the system due to the phenomenon called "Raman scattering," in which individual photons bounce off the fibers molecular structure and change their energies. Scattering produces photons that look as if they might be one half of a pair, but arent......... Posted by: Kevin      Read more         Source

April 12, 2007, 6:28 PM CT

Quantum dot lasers

Physicists at the National Institute of Standards and Technology (NIST) and Stanford and Northwestern Universities have built micrometer-sized solid-state lasers in which a single quantum dot can play a dominant role in the devices performance. Correctly tuned, these microlasers switch on at energies in the sub-microwatt range. These highly efficient optical devices could one day produce the ultimate low-power laser for telecommunications, optical computing and optical standards.

How small can a laser get? The typical laser has a vast number of emitterselectronic transitions in an extended crystal, for exampleconfined within an optical cavity. Light trapped and reflecting back and forth in the cavity triggers the cascade of coherent, laser light. But about a decade ago, scientists made the first quantum dot laser. Quantum dots are nanoscale regions in a crystal structure that can trap electrons and holes, the charge carriers that transport current in a semiconductor. When a trapped electron-hole pair recombines, light of a specific frequency is emitted. Quantum-dot lasers have attracted attention as possible embedded communications devices not only for their small size, but because they switch on with far less power then even the solid-state lasers used in DVD players......... Posted by: Kevin      Read more         Source

April 12, 2007, 6:18 PM CT

Titanium Dioxide: It Slices, It Dices

Chemists from the National Institute of Standards and Technology (NIST) and Arizona State University have proposed an elegantly simple technique for cleaving proteins into convenient pieces for analysis. The prototype sample preparation method, detailed recently in Analytical Chemistry,* uses ultraviolet light and titanium dioxide and could be ideal for new microfluidic "lab-on-a-chip" devices designed to rapidly analyze minute amount of biological samples.

Because most proteins are very large, complex molecules made up of hundreds or thousands of amino acids, they commonly must be cut up into more manageable pieces for analysis. Today, this most usually is done by using special enzymes called "proteases" that sever the chains at well-known locations. The protease trypsin, for example, cuts proteins at the locations of the amino acids lysine and arginine. Analyzing the residual fragments can identify the original protein. But enzymes are notoriously fussy, demanding fairly tight control of temperature and acidity, and the enzymatic cutting process can be time-consuming, from a matter of hours to days.

For a "radically" different approach, the NIST group turned to a semiconductor material, titanium dioxide. Titanium dioxide is a photocatalyst-when exposed to ultraviolet light its surface becomes highly oxidizing, converting nearby water molecules into hydroxyl radicals, a short-lived, highly reactive chemical species.** In the NIST experiments, titanium dioxide coatings were applied to a variety of typical microanalysis devices, including microfluidic channels and silica beads in a microflow reactor. Shining a strong UV light on the area, in the presence of a protein solution, creates a small "cleavage zone" of hydroxyl radicals that rapidly cut nearby proteins at the locations of the amino acid proline......... Posted by: Sarah      Read more         Source

April 11, 2007, 10:54 PM CT

Earthshaking Images

The powerful earthquake struck suddenly, shaking the seven-story building so hard it bent, cracked and swayed in response.

But this was no ordinary earthquake. In a groundbreaking series of tests, engineering scientists from UC San Diego's Jacobs School of Engineering jarred a full-size 275-ton building erected on a shake table, duplicating ground motions recorded during the January 17, 1994 Northridge earthquake in Los Angeles, California.

To record the impact on the building, the structure was fitted with some 600 sensors and filmed as the shake table simulated the earthquake, yielding a flood of data including stress, strain, and acceleration -- so much information that engineers were having a hard time making sense of it all.

That's where visualization experts from the San Diego Supercomputer Center (SDSC) at UC San Diego came in.

"By recreating the shake table experiment in movies in a virtual environment based on the observed data, this lets engineers explore all the way from viewing the 'big picture' of the entire building from a 360-degree viewpoint to zooming in close to see what happened to a specific support," said SDSC visualization scientist Amit Chourasia. "Integrating these disparate data elements into a visual model can lead to critical new insights." ......... Posted by: Tyler      Read more         Source

April 11, 2007, 9:27 PM CT

Earliest Evidence Of Maize Farming In Mexico

A Florida State University anthropologist has new evidence that ancient farmers in Mexico were cultivating an early form of maize, the forerunner of modern corn, about 7,300 years ago - 1,200 years earlier than scholars previously thought.

Professor Mary Pohl conducted an analysis of sediments in the Gulf Coast of Tabasco, Mexico, and concluded that people were planting crops in the "New World" of the Americas around 5,300 B.C. The analysis extends Pohl's prior work in this area and validates principles of microfossil data collection.

The results of Pohl's study, which she conducted along with Dolores R. Piperno of the National Museum of Natural History in Washington, D.C. and the Smithsonian Tropical Research Institute in the Republic of Panama, Kevin O. Pope of Geo Arc Research and John G. Jones of Washington State University, would be reported in the April 9-13 edition of the journal Proceedings of the National Academy of Sciences.

"This research expands our knowledge on the transition to agriculture in Mesoamerica," Pohl said. "These are significant new findings that fill out knowledge of the patterns of early farming. It expands on research that demonstrates that maize spread quickly from its hearth of domestication in southwest Mexico to southeast Mexico and other tropical areas in the New World including Panama and South America"......... Posted by: William      Read more         Source