January 10, 2007, 9:04 PM CT

Automated System Installs Pavement Markers

On rainy nights in Georgia and across the nation, drivers greatly benefit from small, reflective markers that make roadway lanes more visible. A new automated system for installing the markers is expected to improve safety for workers and drivers.

There are more than three million of these safety devices, called raised pavement markers (RPMs), in service on Georgia highways. They are installed and then need to be replaced about every two years by road crews who consider the task one of the riskiest they face. Workers typically ride on a seat cantilevered off the side of a trailer just inches from highway traffic.

Manual RPM placement is not only risky for personnel, but it is also expensive and time-consuming. A typical RPM placement operation includes four vehicles and a six-person crew. All the vehicles must stop at each marker location, so there is tremendous wear on the equipment and increased fuel use.

The Georgia Department of Transportation (GDOT) believed there was a better way to do it and funded the Georgia Tech Research Institute (GTRI) to develop a first-of-its-kind system capable of automatically placing RPMs along the lane stripes while in motion. After almost three years of research and development, GTRI expects to deliver a prototype system early this year. Because of widespread interest in the system, scientists will present a report on their project on Jan. 23 at the National Research Council's Transportation Research Board Annual Meeting in Washington, D.C.........

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January 7, 2007, 9:48 PM CT

Cheaper LEDs from Zinc Oxide

Engineers at UC San Diego have synthesized a long-sought semiconducting material that may pave the way for an inexpensive new kind of light emitting diode (LED) that could compete with today's widely used gallium nitride LEDs, as per a new paper in the journal Nano Letters.

To build an LED, you need both positively and negatively charged semiconducting materials. In an LED, when an electron meets a hole, it falls into a lower energy level and releases energy in the form of a photon of light. The UC San Diego engineers synthesized zinc oxide (ZnO) nanoscale cylinders that transport positive charges. The so-called "p-type ZnO nanowires" are endowed with a supply of positive charge carrying "holes" that, for years, have been the missing ingredients that prevented engineers from building LEDs from ZnO nanowires. In contrast, making "n-type" ZnO nanowires that carrier negative charge (electrons) has not been a problem. The starting materials and manufacturing costs for ZnO LEDs are far less expensive than those for gallium nitride LEDs.

Deli Wang, an electrical and computer engineering professor from UCSD's Jacobs School of Engineering, and his colleagues at UCSD and Peking University, report synthesis of high quality p-type zinc oxide nanowires in a paper published online by the journal Nano Letters.........

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December 27, 2006, 5:06 AM CT

Mixed Prairie Grasses Better Source Of Biofuel

Diverse mixtures of native prairie plant species have emerged as a leader in the quest to identify the best source of biomass for producing sustainable, bio-based fuel to replace petroleum.

A new study led by David Tilman, an ecologist at the University of Minnesota, shows that mixtures of native perennial grasses and other flowering plants provide more usable energy per acre than corn grain ethanol or soybean biodiesel and are far better for the environment. The research was supported by the National Science Foundation (NSF) and the University of Minnesota Initiative for Renewable Energy and the Environment.

"Biofuels made from high-diversity mixtures of prairie plants can reduce global warming by removing carbon dioxide from the atmosphere. Even when grown on infertile soils, they can provide a substantial portion of global energy needs, and leave fertile land for food production," Tilman said.

The findings appear in the Dec. 8, 2006, issue of the journal Science.

The is study based on 10 years of research at Minnesota's Cedar Creek Natural History Area, one of 26 NSF long-term ecological research (LTER) sites. It shows that degraded agricultural land planted with diverse mixtures of prairie grasses and other flowering plants produces 238 percent more bioenergy on average than the same land planted with various single prairie plant species, including switchgrass.........

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December 25, 2006, 4:34 PM CT

New Possibilities For Magnetic Storage

For about ten years now, tiny magnetic structures measuring a few millionths of a millimetre have met with growing interest from the worlds of science and technology, especially on account of their potential applications in magnetic storage. A fascinating quantum mechanical phenomenon occurs in these structures: the vortex core, which has been predicted in theory for forty years, but which experiments revealed only four years ago. In small magnetic plates, the magnetised areas often come together to form level closed magnetic circuits - these are the vortices. Imagine walking with an atom-sized compass in a vortex. The compass needle would always be level, unless you approached its centre, the vortex. There the atomic magnetic compass needles rise from the surface and a magnetic field is created over a tiny radius of around 20 atoms, the largest possible in the material.

The magnetic needles can point either up or down in the vortex core (fig. 1). However, if this property is to be used for magnetic storage, a way must be found to combat the enormous stability typical of vortex structures. Up to now, very high external magnetic fields of around half a Tesla were mandatory to reverse the vortex core. That is approximately one third of the field that the strongest permanent magnet is capable of delivering.........

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December 22, 2006, 5:18 AM CT

Strange Properties Of Superfluids

Princeton University electrical engineers are using lasers to shed light on the behavior of superfluids -- strange, frictionless liquids that are difficult to create and study. Their technique allows them to simulate experiments that are difficult or impossible to conduct with superfluids.

The odd behavior of particles in superfluids, which move together instead of at random, has been observed in light waves that pass through certain materials known as nonlinear crystals. The team relied on this underappreciated correlation to use laser light as a substitute, or model, for superfluids in experiments. Their results would be published in the January 2007 issue of Nature Physics.

Their work could heighten the current understanding of condensed matter physics as well as lead to advances in sensor technology, atomic trapping and optical communications.

"Once you realize you can use light to model a superfluid, a new world opens up," said Jason Fleischer, a Princeton assistant professor of electrical engineering who led the team. "An entire field of physics is interested in studying the dynamics of superfluids, but the experiments are difficult to do. It's a lot easier to conduct the experiments with lasers".

Fleischer and Princeton Engineering graduate students Wenjie Wan and Shu Jia validated their technique by generating results that matched data from previous superfluid experiments. They went on to study superfluid waves and interactions that had not been considered before, either theoretically or experimentally. For instance, they explored the collisions of circular waves similar to those created by drops of water falling into a puddle.........

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December 20, 2006, 4:22 AM CT

Are Nanoparticles Viable Living Forms?

Researchers at Mayo Clinic have successfully isolated nanoparticles from human kidney stones in cell cultures and have isolated proteins, RNA and DNA that appear to be associated with nanoparticles. The findings, which appear in the recent issue of the Journal of Investigative Medicine, are significant because it is one step closer in solving the mystery of whether nanoparticles are viable living forms that can lead to disease -- in this case, kidney stones.

Kidney stones are associated with pathologic calcification, the process in which organs and blood vessels become clogged with calcium deposits that can damage major organs like the heart and kidneys. What causes calcium deposits to build up is not entirely known. Medical scientists at Mayo Clinic are studying calcification at the molecular level in an effort to determine how this phenomenon occurs.

There is a growing body of scientific evidence that links calcification to the presence of nanosized particles, particles so small that some scientists question whether a nanoparticle can live and if so, play a viable role in the development of kidney stones.

The presence of proteins, RNA and DNA does not prove that nanoparticles are viable living forms because a genetic signature has not been identified, says the study's author John Lieske, M.D., a nephrologist with Mayo Clinic. A genetic signature would prove that nanoparticles are indeed living forms that replicate and can cause disease.........

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December 15, 2006, 4:51 AM CT

Scientists Make Liquid Crystal Discovery

What do milk, paint, ink and liquid crystals have in common? Colloids. Findings of Kent State University researchers indicate that manipulating the size of colloids, micron-sized or nanometer-sized particles, can produce huge changes in the material properties of liquid crystals.

In a recently published article in the scholarly journal Physical Review Letters, the researchers illustrate that when the concentration and size of the colloids and liquid crystals are properly tuned, the systems formed promise a new technique for synthesizing liquid crystals with specific molecular properties. The ferroelectric nanoparticles have a significant impact on the material properties of the liquid crystal host; meanwhile they are stable in the liquid crystals and invisible to naked eye.

Manipulation of these systems also leads to reduction in the amount of power mandatory to run liquid crystal displays, such as computer screens, and could result in creation of a range of different liquid crystal materials for a wide variety of applications.........

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December 5, 2006, 4:38 AM CT

The art and science of sensors

A forest ranger helicopter flies over a forest, scattering sensors that can relay temperature data to the ranger station. To ensure minimal environmental impact with maximum robustness, the sensors are very simple: they are basically tiny, sturdy thermometers. After the sensors are scattered, they might be moved further by winds, rains, rivers, or even animals. Is there a way to take the local information sent by the sensor network and turn it into global information about the existence and location of fires in the forest" In particular, without knowing the exact locations of the sensors, can one nevertheless glean information about the coverage area of the sensor network".

As sensor technology has exploded, such fundamental questions have come to the forefront in a number of areas. In particular, national security measures increasingly depend on sensor technology to detect, for example, radiological or biological hazards, hidden mines and munitions, or specific individuals in a crowd. Mathematics, particularly the area of topology, provides a way of addressing such questions.

The January 2007 issue of the Notices of the AMS will carry the article "Homological Sensor Networks" by Vin de Silva and Robert Ghrist. The article describes new results by the authors, which demonstrate how homology theory provides fundamental insights useful in analyzing sensor networks.........

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December 3, 2006, 8:42 PM CT

Measuring Very Short Laser Pulses

Researchers have perfected a technique for very accurately measuring and controlling the electromagnetic waves within some of the shortest laser pulses ever made, says new research published recently. Being able to fully understand and control these laser pulses represents an important step towards using them to track and manipulate electrons in leading-edge research at the sub-atomic level.

The study, published in Nature Physics, focused on extremely short laser pulses, less than 10 femtoseconds long - a femtosecond is one million-billionth of a second. These laser pulses can allow researchers to move and control the electrons in atoms and molecules, and to understand, for example, how molecules are formed. To achieve this reliably, the pulse of electromagnetic waves emitted from the laser must be controlled and measured with a precision which, until now, has been very hard to achieve.

The team of physicists from Imperial College London attained an unprecedented level of accurate measurement by firing the femtosecond laser pulse into a sample of gas, which responds by emitting an x-ray pulse which is even shorter in duration - up to 10 times shorter than the original laser pulse. The scientists observed that the spectrum of the x-ray pulse has encoded within it all the information necessary to precisely reconstruct the waveform of the original laser pulse. Through careful measurements and some 'intelligent' software designed specifically for this purpose, the scientists were therefore able, for the first time, to measure the waveform of individual femtosecond pulses.........

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December 1, 2006, 5:07 AM CT

Theory Of Oscillations May Explain Biological Mysteries

New mathematical studies of the interactions between oscillating biological populations may shed light on some of the toughest questions in ecology, including the number and types of species in an ecosystem, as per an article in the December 2006 issue of BioScience. The article, by John Vandermeer of the University of Michigan, shows how extensions of established theory suggest that a number of animal and plant populations oscillate in synchrony because of interactions such as predation and competition. Such synchronization can have far-reaching effects. Vandermeer suggests that several well-known biological conundrums, such as the higher-than-expected diversity of plankton in aquatic ecosystems, may be explained this way.

Physicists know that even a weak coupling between oscillating systems can yield synchronized oscillations, a phenomenon that was studied with pendulums by the seventeenth century Dutch mathematician Christiaan Huygens. Biologists have only in recent years started to explore the implications for their subject. But it is already clear that coupled oscillating biological populations can give rise to potentially important effects such as synchronized chaos: the interaction between two weakly competing consumers of a food resource can be transformed by the arrival of a third competitor to provide unpredictable opportunities for the newcomer to invade. Vandermeer holds out hopes that the study of oscillations in biological populations will lead to insights into complex systems, such as those that include animals that eat other predators as well as omnivores that eat both predators and those predators prey.........

Posted by: Kevin      Permalink         Source