New technologies wirelessly transmit high-definition video.
A trip across the showroom floor at last week's Consumer Electronics Show (CES) in Las Vegas pointed to a home entertainment trend: bulky cabinets that hold boxy televisions, stereos, and media players are out, and flat-panel displays on walls are in. But as good as those skinny displays look, they still pose the aesthetic and logistical challenge of what to do with the wires connected to them. Now, a handful of companies are racing to outfit televisions, media players, video cameras, and gaming systems with wireless chips that can cut some of those cords.
At CES, SiBeam demonstrated its wireless chipset, which could stream high-definition video and audio from a media player to a television. With SiBeam's technology, it would be possible to hang a television on a wall and place the media player in the same room, but far away and out of sight, without wiring the two together. In the demonstration, the company sent data from the media player to the television at a rate of two gigabits per second, fast enough for standard high-definition video, which is known as 1080i. But the company's first commercial chips--available in Panasonic displays in early 2009--will be better. They will transmit data at four gigabits per second, fast enough to stream the highest-quality high-definition video, 1080p.
http://www.technologyreview.com/Infotech/20086/
Helium isotopes reveal hidden stores of geothermal energy.
Most geothermal power plants exploit the relatively rare but easy to spot hot water associated with volcanoes, limiting geothermal energy to a niche role in meeting global energy demand. It works well in Iceland and a few other places, but geothermal energy is a largely untapped resource in much of the world, in part because, in the absence of a volcano or hot springs, it's hard to find the right spot to tap into the resource. Last week, a pair of geochemists published a report in Science showing that the ultrasensitive detection of traces of helium at the surface using mass spectrometers may hold the key to sniffing out the best sites of this hidden heat.
Mack Kennedy, a senior scientist at Lawrence Berkeley National Laboratory, in Berkeley, CA, and coauthor Matthijs van Soest, an associate research professional at Arizona State University's School of Earth and Space Exploration, in Tempe, measured the levels of helium isotopes to predict areas where the rock is permeable deep underground. Water is more likely to circulate rapidly through such regions, providing the circulation of heat emanating from the earth's mantle or generated in its crust by radioactive decay. "You have a huge resource, and now I can tell you where there's good permeability," says Kennedy. "Those are places to go look for a natural geothermal system right off the bat."
The findings could be an important step in efforts to unlock the vast potential of geothermal energy, in which heated water produces steam to drive power-generating turbines. According to a recent expert panel analysis for the Department of Energy (DOE), led by researchers at MIT and Southern Methodist University, in Texas, geothermal systems engineered to exploit hot rocks could be meeting 10 percent of U.S. electricity demand within 50 years. Currently, geothermal systems supply less than 1 percent of that demand. One challenge to further exploiting geothermal energy has been pinpointing exactly where to look for rocks with the right combination of permeability and heat. And that's where the new study could help.
http://www.technologyreview.com/Energy/19891/
Researchers have fashioned a high-temperature-superconductor crystal into a structure that generates t-rays, electromagnetic waves with a frequency near one terahertz. Although the superconductor-based technique is not yet ready for commercial use, it offers a new option for exploiting this region of the spectrum for a variety of applications, including airport security and medical monitoring.
Because terahertz radiation penetrates many millimeters into tissue, it could enable new medical-imaging techniques. T-rays have also been used in prototype security systems, where they pass readily through fabrics and packaging to reveal concealed weapons and the spectral fingerprints of toxins and explosives.
In spite of its potential, however, the terahertz region hasn't been widely exploited, partly due to limitations of current sources. "All the different sources that are available have nuances that make them not quite exactly what people want," says John Federici, a professor of physics at the New Jersey Institute of Technology, who works on generation schemes based on large pulsed lasers.
Superconductors could provide a solution, says Ulrich Welp, of Argonne National Laboratory, who led the new research. In particular, Josephson junctions--two superconducting slabs separated by a thin insulator--emit high frequencies and occur naturally in the atomic structure of high-temperature superconductors.
The problem is that a single junction emits only a tiny amount of terahertz radiation. "People have worked for a long time to get high-frequency radiation from these intrinsic Josephson junctions," says Welp, but "the power was limited to the picowatt range". He says that his team's new devices, described in the November 23 issue of Science, emit much more power: about half a microwatt.
Researchers have long recognized that combining the output from many junctions could boost the power. "The problem was always to synchronize this large number of junctions," says Welp. To solve this problem, the group started with single crystals of bismuth strontium calcium copper oxide, better known as BSCCO, grown by team members in Japan. The group then used standard processing techniques to etch away parts of the crystal, leaving a flat-topped plateau about a micron high and tens of microns wide.
The etched edges of this mesa reflect radiation traveling along the surface, turning the raised structure into a "cavity" that traps the radiation, Welp says. "We synchronize these junctions through a cavity resonance, just like in a [semiconductor] laser--a standing electromagnetic wave inside a sample, which forces all these junctions to oscillate in phase, coherently." As a signature of coherence, the team found that the power output rose not in proportion to the number of active junctions, but as the square of that number, suggesting that their electric fields are summing together, not just their emission.
http://www.technologyreview.com/Nanotech/19910/
