February 19, 2007, 7:07 PM CT

Image of Frequency Combs

Physicists at the National Institute of Standards and Technology (NIST) have taken the first ever two-dimensional pictures of a "frequency comb," providing extra information that enhances the comb's usefulness in optical atomic clocks, secure high-bandwidth communications, real-time chemical analysis, remote sensing, and the ultimate in precision control of atoms and molecules.

The work, described in the Feb. 8 issue of Nature,* demonstrates a novel method for separating and identifying thousands of individual colors-or frequencies-of visible light while simultaneously measuring intensity and imaging the results in real time. The pictures transform frequency combs, long imagined as one-dimensional, like hair combs in which individual teeth represent specific frequencies, into two-dimensional brushes, in which a number of rows of bristles represent frequencies.

"This is really the first time we've seen individual elements of the stabilized comb, without interacting it with atoms or probing it with another laser, and it turns out to look more like a brush than a comb," says lead author Scott Diddams. "We now can see all the bristles at once with high precision."

Frequency combs are a measurement tool designed and used at NIST and other laboratories for frequency metrology and optical atomic clocks. By providing a second dimension to the typical output of a frequency comb, the new technique efficiently packs more data into a given area without sacrificing precision. All light waves are displayed simultaneously, with a comb resolution as narrow as any other yet demonstrated. In the latest experiments reported in Nature, the scientists made a comb using an ultrafast laser that emits a continuous train of about a billion pulses of light per second, each lasting just a few millionths of a billionth of a second and containing millions of different colors......... Posted by: Kevin      Read more         Source

February 15, 2007, 4:38 AM CT

Lsu Professor Resolves Einstein's Twin Paradox

Delaune Distinguished Professor of Electrical and Computer Engineering at LSU, recently resolved the twin paradox, known as one of the most enduring puzzles of modern-day physics.

First suggested by Albert Einstein more than 100 years ago, the paradox deals with the effects of time in the context of travel at near the speed of light. Einstein originally used the example of two clocks one motionless, one in transit. He stated that, due to the laws of physics, clocks being transported near the speed of light would move more slowly than clocks that remained stationary. In more recent times, the paradox has been described using the analogy of twins. If one twin is placed on a space shuttle and travels near the speed of light while the remaining twin remains earthbound, the unmoved twin would have aged dramatically in comparison to his interstellar sibling, as per the paradox.

If the twin aboard the spaceship went to the nearest star, which is 4.45 light years away at 86 percent of the speed of light, when he returned, he would have aged 5 years. But the earthbound twin would have aged more than 10 years! said Kak.

The fact that time slows down on moving objects has been documented and verified over the years through repeated experimentation. But, in the prior scenario, the paradox is that the earthbound twin is the one who would be considered to be in motion in relation to the sibling and therefore should be the one aging more slowly. Einstein and other researchers have attempted to resolve this problem before, but none of the formulas they presented proved satisfactory......... Posted by: Kevin      Read more         Source

February 13, 2007, 9:34 PM CT

The second humanoid robot in France

The HOAP3 humanoid robot has just arrived at the Laboratory for Computer Science, Robotics and Microelectronics of Montpellier (LIRMM CNRS University of Montpellier 2). This platform supplements the one that was installed at the LAAS in Toulouse last June. They were both made in Japan and represent a strong robotics research potential for France.

Research activities in the field of human robotics are expanding rapidly. The establishment of the JRL (Joint Japanese-French Robotics Laboratory) based in both Japan (Tsukuba) and France (Toulouse-LAAS and Montpellier-LIRMM) contributed strongly to the realization, reinforcement and dynamization of the robotics research community in this field. The two humanoid robots are at the core of JRL's research.

The acquisition of HOAP3 by LIRMM, 50% co-financed by the CNRS, is part of this process. Within the framework of JRL-France, the LIRMM will thus offer the national community an open experimental platform for the validation of models or control methods contributing to ambulation and the handling of objects while maintaining balance.

This 8.8 kg, 60 cm tall robot has 28 motorized articulations. It has a large number of sensors including accelerometers, rate gyros, an infra-red range finder, pressure sensors and two cameras. This unit is based around a completely open software platform (RTLinux) allowing all of the researchers interested to freely evaluate and test their new theoretical developments concerning the modeling, control, vision or learning of these......... Posted by: Kevin      Read more         Source

February 13, 2007, 9:06 PM CT

Nuclear Fusion As Energy Source

For about six months of the year, bursts of a hot, electrically charged gas, or plasma, swirl around a donut-shaped tube in a special MIT reactor, helping researchers learn more about a potential future energy source: nuclear fusion.

During downtimes when the reactor is offline, as it is right now, engineers make upgrades that will help them achieve their goal of making fusion a viable energy source--a long-standing mission that will likely continue for decades.

MIT's reactor, known as Alcator C-Mod, is one of several tokamak plasma discharge reactors in the world. Inside the reactor, magnetic fields control the superheated plasma (up to 50 million degrees Kelvin) as it flows around the tube.

Fusion occurs when two deuterons, or one deuteron and one triton--nuclei of heavy hydrogen--fuse, creating helium and releasing energy. The reactions can only occur at extremely high temperatures.

Eventhough MIT's reactor is smaller than others, it has a stronger magnetic field than some larger reactors, allowing the plasma to become denser at comparable temperatures. "That positions us to provide important data you can't get anywhere else," said Earl Marmar, head of MIT's Alcator C-Mod project and senior research scientist in the Department of Physics......... Posted by: Kevin      Read more         Source

February 12, 2007, 9:46 PM CT

Finding survivors, protecting drivers

At the IEEE International Solid-State Circuits Symposium, Assistant Professor Hossein Hashemi of the USC Ming Hsieh department of electrical engineering will discuss two radar chips created in his laboratory, both of which detect and generate radio signals, parallel to chips used in cell phones and other wireless devices.

But the new devices also accurately scan, accurately focusing precise beams in specific directions, and also do the reverse, detect, accurately determining the direction of incoming signals.

And unlike other high performance chips with these functions, the USC researchers' designs use ordinary CMOS silicon bases, allowing extremely economical fabrication in standard chip foundries.

As per Hashemi, one chip operating in the 24 GHz range uses an ingenious architecture that combines the functionality of multiple coherent transmitters-receivers ('transceivers'), making it much more compact than prior arrays.

This chip has already attracted the attention of General Motors for possible use in car radar, because ten such devices could be installed in a car for a little more than $100 - less than a tenth of what single devices now in use for car self-parking and blind spot detection systems cost.

These chips can guide parking, and not only detect other vehicles but also pedestrians......... Posted by: Jim      Read more         Source

February 11, 2007, 9:40 PM CT

Speed limit for future superconducting magnet

A research team led by a Northwestern University physicist has identified a high-temperature superconductor -- Bi-2212, a compound containing bismuth -- as a material that might be suitable for the new wires needed to one day build the most powerful superconducting magnet in the world, a 30 Tesla magnet.

The material currently used in magnetic resonance (MR) imaging machines in both hospitals and research laboratories -- a low-temperature superconducting alloy of the metallic element niobium -- has been pushed almost as far as it can go, to around 21 Tesla. (Tesla is used to define the intensity of the magnetic field.) There are no superconducting magnet wires currently available that can generate 30 Tesla.

"A new materials technology -- such as a technology based on high-temperature superconductivity -- is mandatory to make the huge leap from 21 Tesla to 30 Tesla," said William P. Halperin, John Evans Professor of Physics and Astronomy in the Weinberg College of Arts and Sciences at Northwestern, who led the team. "We have shown that Bi-2212 could be operated at the same temperature as is presently the case for magnets made with niobium -- 4 degrees Kelvin -- and also achieve the stable state necessary for a 30 Tesla magnet".

The findings will be published online Feb. 11 by the journal Nature Physics.........

Posted by: Kevin      Read more         Source

February 9, 2007, 4:38 AM CT

Nanotechnology meets biology

The object of fascination for most is the DNA molecule. But in solution, DNA, the genetic material that hold the detailed instructions for virtually all life, is a twisted knot, looking more like a battered ball of yarn than the famous double helix. To study it, researchers generally are forced to work with collections of molecules floating in solution, and there is no easy way to precisely single out individual molecules for study.

Now, however, researchers have developed a quick, inexpensive and efficient method to extract single DNA molecules and position them in nanoscale troughs or "slits," where they can be easily analyzed and sequenced.

The technique, which as per its developers is simple and scalable, could lead to faster and vastly more efficient sequencing technology in the lab, and may one day help underpin the ability of clinicians to obtain customized DNA profiles of patients.

The new work is reported this week (Feb. 8, 2007) in the Proceedings of the National Academies of Science (PNAS) by a team of researchers and engineers from the University of Wisconsin-Madison.

"DNA is messy," says David C. Schwartz, a UW-Madison genomics researcher and chemist and the senior author of the PNAS paper. "And in order to read the molecule, you have to present the molecule".........

Posted by: Kevin      Read more         Source

February 7, 2007, 8:24 PM CT

Forensic Photography Brings Color Back

Archaeologists are now turning to forensic crime lab techniques to hunt for dyes, paint, and other decoration in prehistoric textiles.

Eventhough ancient fabrics can offer clues about prehistoric cultures, often their colors are faded, patterns dissolved, and fibers crumbling. Forensic photography can be used as an inexpensive and non-destructive tool to analyze these artifacts more efficiently, as per new Ohio State University.

Forensic photography helps scientists collect information from fragile artifacts before using expensive chemical tests, which cause damage during material sampling. The forensic method also helps scientists narrow areas to sample for colorants, ultimately reducing artifact damage and testing costs.

"Normally when you dig artifacts out of the ground, particularly stone or ceramic ones, you wash them and they look sexy. But you can't do that with textiles," said Christel Baldia, Ohio State University doctoral graduate in textiles and clothing. Baldia conducted the study with Kathryn Jakes, professor of textile sciences in the College of Education and Human Ecology at Ohio State, and published their findings in the April, 2007 issue of Journal of Archaeological Science.

Putting forensic photography to the test, Baldia and Jakes examined textiles from burial mounds built by the Hopewell, a prehistoric Native American people that flourished about 1600 years ago. In their study, the two researchers focused on pieces of fabric recovered from Ohio 's Seip burial mounds in southern Ohio. Experts believe some of the pieces belonged to a canopy of fabric that arched over the remains buried inside the mounds.........

Posted by: William      Read more         Source

February 2, 2007, 4:51 AM CT

Improved Nanodots

The massive global challenge of storing digital data-storage needs reportedly double every year-may be met with a tiny yet powerful solution: magnetic particles just a few billionths of a meter across. This idea is looking better than ever now that scientists at the National Institute of Standards and Technology (NIST) and collaborators have made nanodot arrays that respond to magnetic fields with record levels of uniformity. The work enhances prospects for commercially viable nanodot drives with at least 100 times the capacity of today's hard disk drives.

A nanodot has north and south poles like a tiny bar magnet and switches back and forth (or between 0 and 1) in response to a strong magnetic field. Generally, the smaller the dot, the stronger the field mandatory to induce the switch. Until now scientists have been unable to understand and control a wide variation in nanodot switching response. As described in a new paper,* the NIST team significantly reduced the variation to less than 5 percent of the average switching field and also identified what is thought to bethe key cause of variability-the design of the multilayer films that serve as the starting material for the nanodots.

Nanodots, as small as 50 nanometers (nm) wide, were fabricated using electron beam lithography to pattern multilayer thin films. The key was to first lay down a tantalum "seed layer" just a few nanometers thick when making a multilayer film of alternating layers of cobalt and palladium on a silicon wafer. The seed layer can alter the strain, orientation or texture of the film. By making and comparing different types of multilayer stacks, the scientists were able to isolate the effects of different seed layers on switching behavior. They also were able to eliminate factors previously suspected to be critical, such as lithographic variations, nanodot shape or crystal grain boundaries.........

Posted by: Kevin      Read more         Source

February 1, 2007, 8:11 PM CT

Apex USB battery charger

Think of all those consumer electronics we power with disposable batteries. Now think about how all those batteries find themselves in the dumpster, headed for land fills. Rechargeable is definitely the way to go. With the Apex USB charger, four batteries can charge in four hours by plugging into your computer's USB port.

The unit is small, just four inches square and one inch high, perfect for traveling. However, unlike the USB cell batteries, which have gotten a lot of attention lately, they do not have a USB port directly attached to the battery case. Not as cool perhaps, but probably more useful, since most laptops tend to have only one or two USB ports, and you get to choose whether to charge AA or AAA batteries in the pack. Not only that, it makes a great carrying case for your spare set of batteries; as you use one set, the other can be charging nicely or stowed and ready-to-go.........

Posted by: Kevin      Read more         Source