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Brighter LEDs Could Give Lightbulbs The Boot


Light-emitting diodes are likely to replace old-fashioned bulbs someday. They use a fraction of the power and can last 100 times as long. Yet while they have shown up in car signals and traffic lights, LEDs have so far been too costly to supplant the bulbs and tubes that light houses, offices, and factories.

Cheaper, brighter LEDs may soon make inroads in these spaces, too. A group led by E. Fred Schubert, professor of electrical engineering at Rensselaer Polytechnic Institute, has patented a new design for LEDs using "omni-directional reflectors" (ODRS) that amplify total light output. Compared with conventional LEDs, they deliver up to twice as much light, says Schubert. The key is the ODRs' ability to reflect photons even at extreme angles. Current designs, Schubert adds, often convert these photons into heat rather than emit them as light.

The new diodes will be cooler and more reliable, and each application will require fewer of them. That, plus the fact that the manufacturing process doesn't change much, should help bring prices down. One LED maker is ready to test the new design, and devices could be on the market in three years.

Cities can prepare for earthquakes more effectively and cheaply if they know the maximum potential threat along certain sections of a fault, says Charles Rubin, a professor at Central Washington University in Ellensburg.

How can they find out? Rubin and his colleagues dug trenches parallel to the San Andreas Fault northeast of Los Angeles to study large earthquakes that preceded a famous quake in 1857. Examining multiple extinct river beds and measuring how they were cleft, they found that the quake-induced gaps from six large earthquakes all measured roughly 7.5 meters. To get this much slip, each quake must have produced ruptures about 220 miles long, and had a magnitude of 7.5 to 8, Rubin says. He is studying other earthquake zones in Taiwan and the U.S. to test the thesis that quakes along each discrete portion of a fault occur at roughly the same magnitude.

BatScap, a French company, has a lithium-polymer battery that may inspire auto makers to produce more environmentally friendly cars. The technology has already been proven in smaller devices such as laptops, cameras, and iPods, but BatScap says this is the first such battery that's large enough to power a vehicle.

A unit of conglomerate Bollor?, BatScap spent $85 million and 12 years developing the cell. In an electric car, it would need recharging only once every 120 to 180 miles, BatScap claims, and could go 93,000 miles without needing to be replaced. Vincent Bollor?, CEO of the parent company, says running his battery will cost consumers just 2 cents a mile, saving owners $2,500 a year in gasoline and other costs. He hopes to show it off in an electric car at the Salon Automobile de Gen?ve next March.

The batteries may not fully address one of the biggest complaints about electric cars: poor performance. But the same technology could bring big benefits to gas-electric hybrids, says BatScap.

-- For years scientists have assumed that insect attacks on plants limit biodiversity in the rainforest. But when researchers from the University of Utah and the National University of the Peruvian Amazon studied local insects interacting with transplanted trees, they discovered the opposite. Plants that devote energy to fending off insects grow more slowly -- a handicap that sometimes prevents them from taking over whole terrains at the expense of less hardy species. The bugs thus help preserve the variety of niches and habitats, says University of Utah graduate student Paul Fine.

-- Drug-resistant malaria, a growing scourge in many parts of the world, may meet its match in a humble shallow-water sponge. Scientists at L'Institut de Recherche Pour le D?veloppement (IRD) in Paris say members of the sponge genus Phloeodictyon, found near New Caledonia, contain substances with antimalarial properties -- compounds not found in the deepwater varieties. In nature, says IRD chemist C?cile Debitus, the protective molecules may serve to fight off parasites unique to shallow waters.


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