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To Beat A Parasite, Confuse It


Developments to Watch

TO BEAT A PARASITE, CONFUSE IT

CORNFIELDS ACROSS THE country are showing off their green and golden splendor. Hidden underground, however, are the ravages of a billion-dollar blight called rootworm. Pesticides are the standard solution. But researchers at Colorado State University think there is a better, more environmentally friendly way to deal with the parasites: Befuddle them.

The scientists' idea hinges on the recent discovery that rootworm larvae navigate to food sources by detecting the carbon dioxide that corn roots emit. If the larvae don't make it to the roots within 24 hours of hatching, they die. So entomology professor Louis B. Bjostad and his colleagues turned to two ingredients familiar to bakers everywhere: yeast and sodium bicarbonate. The researchers concocted separate recipes of baking soda and yeast, chemically primed to release CO2. Then they tested each one on separate small plots of land. Both recipes produced enough CO2 to steer the larvae away from the roots, causing them to starve. The scientists are planning more extensive trials on larger tracts of land.EDITED BY NEIL GROSS By Elizabeth VeomettReturn to top

THIS `SEEING-EYE DOG' USES SONAR

THE GUIDECANE ISN'T AS warm and fuzzy as a seeing-eye dog. But for the visually impaired, it may be the next step forward. Developed by a mechanical engineer at the University of Michigan, the device resembles a shoe box on wheels connected to a four-foot pole. The box houses an array of ultrasonic sensors and transmitters that quietly ping signals six feet out to the front and sides--10 pings a second.

When the sensors pick up an echo--bounced back by a lamppost or a pedestrian--they send the data to a microprocessor that directs servomotors in the wheels to turn. The processor, which computes a new, rudimentary map of the terrain every 30 milliseconds, resumes its original course once it has circumvented the obstacle. All the user needs to do is provide forward locomotion, says inventor Johann Borenstein, a research scientist at the UM College of Engineering's Mobile Robotics Laboratory.

There are a few glitches. The sonar system occasionally has trouble detecting objects when the reflected echo bounces back at an angle. But that could be remedied with a simple rubber bumper, says Borenstein. He and the university have patented the cane and are seeking corporate partners to help commercialize it. In the future, they hope to build in a global positioning device to guide the user with greater precision. They are also thinking of adding voice-recognition features.EDITED BY NEIL GROSS By Scott LaFeeReturn to top

THE INCREDIBLE SHRINKING QUANTUM DOT

SOMETIME AROUND 2020, THE EVER-SHRINKING TRANSISTOR will be as tiny as it can get. But researchers at the University of Notre Dame report in the Aug. 15 issue of Science that future technology may yield chips with 150,000 times as many transistor-like switches as today's brainiest silicon slivers.

The trick is harnessing the woolly wonders of quantum mechanics--a world in which electrons can "tunnel" through space to relay signals without moving or generating heat. The Notre Dame team demonstrated that tiny quantum dots can process data without relying on wires, which occupy far more space on a chip than transistors do.

Instead of circuit patterns you can see, the prototype has rows of microscopic boxes that resemble the "deuce" faces on dice. The two dots in opposite corners are quantum dots, and they confine a roaming electron to one of the unoccupied corners. Reverse an electric charge at the chip's edge, and the electron in the first box flips to the opposite corner, setting off a chain reaction down the quantum "wire" that pushes the electrons in each successive box to the far-side corner. This can relay a signal or store data without any actual flow of electrons. Today, the dots are large and unwieldy. But as they shrink, team leader Gregory L. Snider, an assistant professor of electrical engineering, envisions chips with trillions of tiny quantum boxes.EDITED BY NEIL GROSS By Otis PortReturn to top


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