June 26, 2008, 8:26 PM CT

3-D Nanostructures with Magnetic Materials

Materials researchers at the National Institute of Standards and Technology (NIST) have developed a process to build complex, three-dimensional nanoscale structures of magnetic materials such as nickel or nickel-iron alloys using techniques compatible with standard semiconductor manufacturing. The process, described in a recent paper,* could enable whole new classes of sensors and microelectromechanical (MEMS) devices.

The NIST team also demonstrated that key process variables are associated with relatively quick and inexpensive electrochemical measurements, pointing the way to a fast and efficient way to optimize the process for new materials.

The NIST process is a variation of a technique called "Damascene metallization" that often is used to create complicated three-dimensional copper interconnections, the "wiring" that links circuit elements across multiple layers in advanced, large-scale integrated circuits. Named after the ancient art of creating designs with metal-in-metal inlays, the process involves etching complex patterns of horizontal trenches and vertical "vias" in the surface of the wafer and then uses an electroplating process to fill them with copper. The high aspect ratio features may range from tens of nanometers to hundreds of microns in width. Once filled, the surface of the disk is ground and polished down to remove the excess copper, leaving behind the trench and via pattern......... Posted by: Kevin      Read more         Source

June 26, 2008, 8:22 PM CT

Much-Anticipated Online Mathematics Reference

The National Institute of Standards and Technology (NIST) has released a five-chapter preview of the much-anticipated online Digital Library of Mathematical Functions (DLMF). In development for over a decade, the DLMF is designed to be a modern successor to the 1964 "Handbook of Mathematical Functions," a reference work that is the most widely distributed NIST publication (with over a million copies in print) and one of the most cited works in the mathematical literature (still receiving over 1,600 yearly citations in the research literature). The preview of the new DLMF is a fully functional beta-level release of five of the 36 chapters.

The DLMF is designed to be the definitive reference work on the special functions of applied mathematics. Special functions are "special" because they occur very frequently in mathematical modeling of physical phenomena, from atomic physics to optics and water waves. These functions have also found applications in many other areas; for example, cryptography and signal analysis. The DLMF provides basic information needed to use these functions in practice, such as their precise definitions, alternate ways to represent them mathematically, illustrations of how the functions behave with extreme values and relationships between functions......... Posted by: Sarah      Read more         Source

June 25, 2008, 10:31 PM CT

Primate's Scent Speaks Volumes

Perhaps judging a man by his cologne isn't as superficial as it seems.

Duke University researchers, using sophisticated machinery to analyze hundreds of chemical components in a ringtailed lemur's distinctive scent, have observed that individual males are not only advertising their fitness for fatherhood, but also a bit about their family tree as well.

"We now know that there's information about genetic quality and relatedness in scent," said Christine Drea, a Duke associate professor of biological anthropology and biology. The male's scent can reflect his mixture of genes, and to which animals he's most closely related. "It's an honest indicator of individual quality that both sexes can recognize," she said.

Lemurs, distant primate cousins of ours who split from the family tree before the monkeys and apes parted ways, have a complex and elaborate scent language that until recently was completely undiscovered by humans. Drea said it's language that is undoubtedly richer than we can imagine.

"All lemurs make use of scent," she said. "The diversity of glands is just amazing".

Ringtailed males have scent glands on their genitals, shoulders and wrists, each of which makes different scents. Other lemur species also have glands on their heads, chests and hands. Add to these scents the signals that can be conveyed in feces and urine, and there's a lot of silent, cryptic communication going on in lemur society......... Posted by: Ashley      Read more         Source

June 23, 2008, 8:01 PM CT

A look into the nanoscale

Lawrence Livermore National Laboratory scientists have captured time-series snapshots of a solid as it evolves on the ultra-fast timescale.

Using femtosecond X-ray free electron laser (FEL) pulses, the team, led by Anton Barty, is able to observe condensed phase dynamics such as crack formation, phase separation, rapid fluctuations in the liquid state or in biologically relevant environments.

Other Livermore researchers include Michael Bogan, Stafan Hau-Riege, Stefano Marchesini, Matthias Frank, Bruce Woods, former Livermore researcher Saša Bajt and former LLNL scientist Henry Chapman, who is now at the Centre for Free Electron Laser Science, DESY, in Hamburg, Gera number of.

"The ability to take images in a single shot is the key to studying non-repetitive behavior mechanisms in a sample," Barty said.

As the femtosecond laser blasts the sample, it is destroyed, but not before the researchers created images with a 50-nanometer spatial resolution, and a 10-femtosecond shutter speed. (A femtosecond is one billionth of one millionth of a second. For context, a femtosecond is to a second as a second is to about 32 million years.).

"This experiment opens the door to a new regime of time-resolved experiments in mesoscopic dynamics," Barty said. "This technique could be extended to a few nanometers spatial and a few tens of femtoseconds temporal resolution"......... Posted by: Kevin      Read more         Source

June 23, 2008, 7:19 PM CT

Light-Driven Reversible Nanoswitches

The ability to see is based on molecules in the eye that flip from one conformation to another when exposed to visible light. Now, a new technique for attaching light-sensitive organic molecules to metal surfaces allows the molecules to be switched between two different configurations in response to exposure to different wavelengths of light. Because the configuration changes are reversible and can be controlled without direct contact, this technique could enable applications that can be controlled at the molecular scale.

The technology has been suggested as a possible basis for molecular motors, artificial muscles, and molecular electronics. The research results, obtained by a team led by Paul S. Weiss, distinguished professor of chemistry and physics at Penn State University and James M. Tour, Chao professor of chemistry at Rice University, are published in the June 2008 issue of the journal Nano Letters.

Until now, progress was impeded because, when such molecules were attached to surfaces, they no longer could be switched back and forth, as they could be when they were in solution. The new technique uses a change in the shape of an azobenzene molecule in response to light to provide two different states. The azobenzene molecule consists of a bridge of two nitrogen atoms attached to one another by a double bond, with each nitrogen atom also bound to a benzene ring. The two benzene rings can be on the same side of the molecule (cis configuration) or on opposite sides (trans configuration). When the molecule absorbs energy, in the form of light, it can change between cis and trans configurations in a process called photoisomerization. "This mechanism is essentially the same that we use in our eyes for vision," said Weiss. "The molecule responds to light by making a change that can be harnessed. In the eye, the change causes a neural impulse"......... Posted by: Kevin      Read more         Source

June 18, 2008, 8:44 PM CT

Ocean temperatures and sea level increases

New research suggests that ocean temperature and associated sea level increases between 1961 and 2003 were 50 percent larger than estimated in the 2007 Intergovernmental Panel on Climate Change report.

The results are published in the June 19 edition of the journal Nature. An international team of researchers, including Lawrence Livermore National Laboratory climate scientist Peter Gleckler, compared climate models with improved observations that show sea levels rose by 1.5 millimeters per year in the period from 1961-2003. That equates to an approximately 2½-inch increase in ocean levels in a 42-year span.

The ocean warming and thermal expansion rates are more than 50 percent larger than prior estimates for the upper 300 meters of oceans.

The research corrected for small but systematic biases recently discovered in the global ocean observing system, and uses statistical techniques that "infill" information in data-sparse regions. The results increase scientists' confidence in ocean observations and further demonstrate that climate models simulate ocean temperature variability more realistically than previously thought.

"This is important for the climate modeling community because it demonstrates that the climate models used for assessing sea-level rise and ocean warming tie in closely with the observed results," Gleckler said......... Posted by: Tyler      Read more         Source

June 17, 2008, 9:40 PM CT

The Mystery of Mass Extinctions Is No Longer Murky

If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits.

But a new study, published June 15, 2008, in the journal Nature, suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions over the past 500 million years.

"The expansions and contractions of those environments have pretty profound effects on life on Earth," says Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics and the author of the new Nature report. In short, as per Peters, changes in ocean environments correlation to sea level exert a driving influence on rates of extinction, which animals and plants survive or vanish, and generally determine the composition of life in the oceans.

Since the advent of life on Earth 3.5 billion years ago, researchers think there may have been as a number of as 23 mass extinction events, a number of involving simple forms of life such as single-celled microorganisms. Over the past 540 million years, there have been five well-documented mass extinctions, primarily of marine plants and animals, with as a number of as 75-95 percent of species lost. For the most part, researchers have been unable to pin down the causes of such dramatic events. In the case of the demise of the dinosaurs, researchers have a smoking gun, an impact crater that suggests dinosaurs were wiped out as the result of a large asteroid crashing into the planet. But the causes of other mass extinction events have been murky, at best......... Posted by: William      Read more         Source

June 16, 2008, 9:28 PM CT

Lower Midwest braces for flood onslaught

Residents of the central and southern Midwest are crossing their fingers, saying their prayers, planning evacuations, and in some cases filling sandbags in preparation for the excessive water ravishing communities in Iowa and Wisconsin.

"The flood wave is propagating down the Mississippi River towards St. Louis at about the pace of a brisk walk," said Robert E. Criss, Ph.D., professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis. "Some areas north of St. Louis in Missouri and southern Iowa are bracing for the second worst flood in their history. This is serious water."

Criss is a geologist. One of his specialties is hydrogeology. He said that the floodwaters are projected to crest at St. Louis at 38 feet on June 22 or 23, marking the 11th time since the Civil War that St. Louis has reached that flood stage. During the flood of 1993 waters at St. Louis crested at 49.6 feet.

The Missouri River at St. Charles on June 13 was 27.6 feet That's close to three feet above flood stage, and it is still rising.

"The water already is in place," Criss noted. "Projecting it downstream doesn't rely on weather predictions."

Indeed, more precipitation is the wild card.

"More rainfall is only going to make problems worse," Criss said. "If the region gets significantly more precipitation during the week of June 16, it could make a place like Winfield, Mo. surpass even its flood of '93 totals."........ Posted by: Tyler      Read more         Source

June 10, 2008, 9:06 PM CT

Rapid Retreat of Arctic Sea Ice

The rate of climate warming over northern Alaska, Canada, and Russia could more than triple during periods of rapid sea ice loss, as per a new study led by the National Center for Atmospheric Research (NCAR). The findings raise concerns about the thawing of permafrost, or permanently frozen soil, and the potential consequences for sensitive ecosystems, human infrastructure, and the release of additional greenhouse gases.

"Our study suggests that, if sea-ice continues to contract rapidly over the next several years, Arctic land warming and permafrost thaw are likely to accelerate," says lead author David Lawrence of NCAR.

The study, by researchers from NCAR and the National Snow and Ice Data Center, will be published Friday in Geophysical Research Letters. It was funded by the U.S. Department of Energy and by the National Science Foundation, NCAR's sponsor.

The research was spurred in part by events last summer, when the extent of Arctic sea ice shrank to more than 30 percent below average, setting a modern-day record. From August to October last year, air temperatures over land in the western Arctic were also uncommonly warm, reaching more than 4 degrees Fahrenheit (2 degrees Celsius) above the 1978-2006 average and raising the question of whether or not the uncommonly low sea-ice extent and warm land temperatures were related......... Posted by: Tyler      Read more         Source

June 10, 2008, 8:23 PM CT

Cutting-edge weapons result of prehistoric experimentation

In today's fast-paced, technologically advanced world, people often take the innovation of new technology for granted without giving much thought to the trial-and-error experimentation that makes technology useful in everyday life. When the "cutting-edge" technology of the bow and arrow was introduced to the world, it changed the way humans hunted and fought. University of Missouri archaeologists have discovered that early man, on the way to perfecting the performance of this new weapon, engaged in experimental research, producing a great variety of projectile points in the quest for the best, most effective system.

"Technological innovation and change has become a topic that interests people," said R. Lee Lyman, professor and chair of the University of Missouri Department of Anthropology. "When the bow and arrow appeared in North America, roughly 1,500 years ago, it eventually replaced the atlatl (spear thrower) and dart. The introduction of the bow and arrow, a different weapon delivery system, demanded some innovative thinking and technology. In other words, one could not just shoot a dart from a bow. Components like the shaft and arrow point needed to be reinvented".

Because the necessary flight dynamics and mechanics of the arrow wouldn't have been fully understood, the indigenous people at the time would have experimentedtrying all sorts of points with different types of shafts, attempting to discover the best combinations. This reinvention process can be seen archaeologically through an increase in the number and variation of projectile pointsindicating the transition period between the atlatl and the bow and arrow......... Posted by: William      Read more         Source