September 19, 2006, 9:01 PM CT

Shocking Scenes From Antarctica

Satellite images acquired from 23 to 25 August 2006 have demonstrated for the first time dramatic openings - over a geographic extent larger than the size of the British Isles - in the Arctic's perennial sea ice pack north of Svalbard, and extending into the Russian Arctic all the way to the North Pole.

Observing data from Envisat's Advanced Synthetic Aperture Radar (ASAR) instrument and the AMSR-E instrument aboard the EOS Aqua satellite, researchers were able to determine that around 5-10 percent of the Arctic's perennial sea ice, which had survived the summer melt season, has been fragmented by late summer storms. The area between Spitzbergen, the North Pole and Severnaya Zemlya is confirmed by AMSR-E to have had much lower ice concentrations than witnessed during earlier years.

Mark Drinkwater of ESA's Oceans/Ice Unit said: "This situation is unlike anything observed in prior record low ice seasons. It is highly imaginable that a ship could have passed from Spitzbergen or Northern Siberia through what is normally pack ice to reach the North Pole without difficulty.

"If this anomaly trend continues, the North-East Passage or 'Northern Sea Route' between Europe and Asia will be open over longer intervals of time, and it is conceivable we might see attempts at sailing around the world directly across the summer Arctic Ocean within the next 10-20 years." .........

Posted by: Tyler      Permalink         Source

September 18, 2006, 9:37 PM CT

Metal deformation studies

By combining very large-scale molecular dynamics simulations with time-resolved data from laser experiments of shock wave propagation through specific metals, scientists at the Lawrence Livermore National Laboratory are now able to better understand the evolution of high-strain-rate plasticity.

Plastic deformation of metals results from the motion of a high density of dislocation lines. A strong shock produces an unusual number of dislocations within a metal's crystalline lattice, which changes the metal's mechanical properties such as strength, ductility and resistance to fracture and cracking.

In a paper published in the Sept. 17 edition of the journal Nature Materials, Livermore researchers, in conjunction with scientists from the University of Oxford, have compared and validated strong shock molecular dynamics simulations to dynamic experimental data in metals.

"We calculated the time needed for the metal to generate defects and relax in a strong shock wave," said Eduardo Bringa, LLNL's lead author of the paper. "We came to understand this time interval in terms of the time needed for line defects (dislocations) to move far enough to relax the strain. It was known that the more dislocations that are produced and the more they move, the more the strain is relaxed".........

Posted by: Sarah      Permalink         Source

September 17, 2006, 10:18 PM CT

Supporting Industrial Zeolites

The National Institute of Standards and Technology (NIST) has issued three new reference materials to support scientists studying the properties of commercially important zeolites.

First described in the 18th century, zeolites have seen increasing use in industry and commerce from cat litter to industrial catalysts and "molecular sieves." Zeolites belong to class of materials called alumino-silicates whose crystal structures form highly porous, nanoscale "cages" that can filter and trap small molecules. Naturally occurring zeolites are mined and widely used as absorbents in products such as cat litter. Tailored synthetic zeolites have a wide variety of more specialized applications, such as in laundry detergents (where they replace pollution-causing phosphates), and as catalysts in oil refineries. Because they can be designed with pores that pass only molecules of a certain size and shape, zeolites have excited considerable interest as molecular sieves for chemical separations--they are used in oxygen generation systems for medical oxygen, for example.

It is often extremely difficult to make precision measurements of key chemical characteristics for zeolites because they are ferociously hygroscopic. Humidity must be precisely controlled--and specified--to make meaningful measurements of the elemental content, for example. This has made it difficult to compare experimental results between different labs.........

Posted by: Sarah      Permalink         Source

September 17, 2006, 10:14 PM CT

Small, low-noise oscillator

A new design for a microwave oscillator that is smaller, simpler, and produces clearer signals at a single frequency than comparable devices has been invented at the National Institute of Standards and Technology (NIST). Applications could include homeland security (e.g., surveillance of radio traffic for anomalous signals, or high-resolution digital imaging radar on unmanned aircraft), telecommunications (e.g., maintaining separation between frequencies in high-bandwidth networks), and perhaps even consumer devices (e.g., satellite television downlinks).

A patent was issued recently* for the NIST oscillator, which is about the size of a roll of 35 mm camera film. NIST scientists have built five prototypes on test fixtures, which offer several-orders-of-magnitude reductions in various types of self-generated signal interference, or noise, in comparison to typical commercial oscillators, resulting in improved frequency stability, as per David Howe, one of the inventors. In addition, the simple design reduces costs and improves reliability, while consuming less power than other oscillators of comparable signal purity. The small size could be an advantage on some surveillance platforms.

Microwave oscillators are used as reference or clock signals in a number of high-precision technologies. Through control of temperature and other variables, the oscillators produce a desired signal at one narrowly defined frequency while suppressing random, electronically induced "noise" generated by components. In the best microwave oscillators, the signal typically is amplified inside a metal cavity containing a solid insulating material that internally sustains microwaves and radio waves with minimal loss, particularly at cryogenic temperatures, an expensive and complex design. By contrast, the NIST oscillator uses an ultra-stiff ceramic manifold that supports a single frequency with either a vacuum or air as the insulating medium.........

Posted by: Kevin      Permalink         Source

September 14, 2006, 8:21 PM CT

Double Quantum Dots Control Kondo Effect

Two quantum dots connected by wires could help researchers better control the Kondo effect in experiments, as per a research studyby Ohio University and University of Florida physicists published in a recent issue of Physical Review Letters.

The Kondo effect occurs when electrons become trapped around the magnetic impurities in semiconductor materials, which prompts the electrons to change their spin. This phenomenon has intrigued scientists, as electronic correlations can create interesting and complex behavior in materials.

In the new work, researchers demonstrate how the two quantum dot system can behave in two different and interesting ways: As a simile for a Kondo-effect system where one quantum dot is used to "filter" the effect of the current leads, and as a way to study "pseudo-gapped" systems and correlations in them, which can help researchers understand structures such as superconductors.

"This last part is of great current interest to theorists and experimentalists who are exploring what are called quantum phase transitions, which are changes in systems that alter their behavior dramatically as a function of some parameter while remaining at zero (or very low) temperature," said Sergio Ulloa, a professor of physics and astronomy at Ohio University.........

Posted by: Kevin      Permalink         Source

September 13, 2006, 9:21 PM CT

Cellular Protein Factories

Proteins of all sizes and shapes do most of the work in living cells, and the DNA sequences in genes spell out the instructions for making those proteins. The crucial job of reading the genetic instructions and synthesizing the specified proteins is carried out by ribosomes, tiny protein factories humming away inside the cells of all living things.

Harry Noller, the Sinsheimer Professor of Molecular Biology at the University of California, Santa Cruz, has been studying the ribosome for more than 30 years. His main goal is to understand how the ribosome works and how it evolved, but there are also practical reasons to pursue this research. Many of the most effective antibiotics work by targeting bacterial ribosomes, and findings by Noller and others have led to the development of novel antibiotics that hold promise for use against germs that have developed resistance to current drugs. Drug-resistant staph infections, for example, are a serious problem in hospitals.

Noller's laboratory achieved breakthroughs in 1999 and 2001, producing the first high-resolution images of the molecular structure of a complete ribosome. Now, his team has made another major advance with an even higher-resolution image that enables them to construct an atom-by-atom model of the ribosome.........

Posted by: Ashley      Permalink         Source

September 13, 2006, 9:07 PM CT

Selective Sensors Based On Carbon Nanotubes

A team of scientists from Arizona State University and Motorola Labs, the applied research arm of Motorola Inc., has developed sensors based on carbon nanotubes, microscopically small structures that posses excellent electronic properties. In early tests, the new devices detected the presence of heavy metal ions in water down to parts per trillion levels.

Specifically, the scientists developed a method for applying peptides to single walled carbon nanotubes (SWNT) in field effect transistors.

"This is a fairly general sensor platform for all kinds of applications," said Nongjian Tao, an electrical engineering professor at Arizona State University and one of the scientists on the project. "We tested heavy metal ions in water, but the platform can be applied to a number of other areas to sense toxic chemicals in the air, or they can be used as biosensors when applied to medicine."

"Integration of nanosensors into devices and sensor networks will enable the detection of biological and chemical agents at very low concentrations, which could be vital in the areas of public safety and homeland security," added Vida Ilderem, vice president of the Embedded Systems Research Labs at Motorola, Tempe, Ariz.

The scientists report the advance in a paper, "Tuning the chemical selectivity of SWNT-FETs for detection of heavy metal ions," which would be reported in the journal Small. An early view of the article is available at the journal's web site (www3.interscience.wiley.com/cgi-bin/jissue/109627347).........

Posted by: Kevin      Permalink         Source

September 13, 2006, 4:45 AM CT

High-tech to reduce wildlife-vehicle collisions

As part of a six-year study, scientists at the Western Transportation Institute at Montana State University have helped test and develop an animal-detection system that may give motorists the upper hand in avoiding crashes with wildlife across the nation.

The system, by Sensor Technologies & Systems of Scottsdale, Ariz., reliably detected elk on U.S. Highway 191 in Yellowstone National Park. How effective the system is in reducing animal-vehicle collisions will be reviewed over the next two years.

The testing and development of the system was just one part of a 271-page report summarizing all the available information on animal-detection systems in the world: data from more than 30 study sites and 15 different animal-detection technologies in place across United States and Europe. One Swiss study showed collisions with large animals were reduced 82 percent in locations with animal-detection systems.

Animal detection systems use passive or active infrared signals, lasers, microwaves, or seismic sensors to activate warning signs that urge drivers to slow down, be more alert, or both, when large animals are on, or near, the road ahead.

"This is a very promising technology that can make U.S. roadways safer. Our results urge us to fine tune this technology so that it can be used across the country," said Marcel Huijser, the study's lead investigator at the WTI.........

Posted by: Jim      Permalink         Source

September 9, 2006, 10:34 AM CT

Restating Earnings Hurts The Company And Peers

No company wants to issue an accounting restatement; it's a guaranteed way for the share price to drop 10 percent, on average. Investors, analysts and journalists alike view restatements as an indication of a problem within the company. As per a professor at the Olin School of Business at Washington University in St. Louis, when a company announces a restatement of revenues or expenses, there is value in looking at its industry peer firms.

Based on an evaluation of more than 22,500 public companies, accounting professor Nicole Thorne Jenkins and her co-authors observed that a company's restatement adversely affects not only its own stock price, but also that of similar firms.

"When a firm announces a restatement, there is a significantly negative market reaction," said Jenkins. "The information communicated by a restatement is transferred to similar firms. The market reacts to that information transfer similarly but to a lesser degree because there is some uncertainty that the same reporting problem exists in other companies."

Upon news of a company's accounting restatement, peer firms experience a cumulative average decrease of 1.82 percent in the 21 days following the initial restatement. The effect is even more pronounced for firms that have poor accounting quality or that have the same auditor as the restating firm.........

Posted by: Mac      Permalink         Source

September 9, 2006, 7:53 AM CT

Ground movement risks identified

Ground movements are responsible for hundreds of deaths and billions of Euros annually, and the threat they pose is increasing due to urbanisation and land use. ESA's GMES Service Element Programme is backing a project, Terrafirma, to help mitigate these risks.

To address these issues, Terrafirma is providing a Pan-European ground motion hazard information service to detect and monitor ground movements in relation to building stability, subsidence and ground heave, landslides, seismic activity and engineered excavations.

For over 15 years, Synthetic Aperture Radar Interferometry (InSAR) has been providing ground deformation data at centimetre precision. In the past five years, however, new ways of processing satellite radar images have been developed using Persistent Scatterer Interferometry (PSI) that allow ground movements over wide areas to be detected and monitored with even greater sensitivity.

Recent statistics show that 50% of the world population already live in cities, and megacities (over 10 million) are now commonplace. As the trend toward urbanisation continues, most major towns will undergo construction to accommodate new developments for newcomers.

New construction requires solid foundations to avoid costly planning mistakes, and underground works and metro-tunnelling have some surface effect that needs remediation and monitoring. The Terrafirma services can provide information to locate low-risk foundation sites and help save money on the remediation of existing structures.........

Posted by: Tyler      Permalink         Source