Developments to Watch
EARTHSHAKING NEWS FROM OLD SPY PIX
OLD SATELLITE PHOTOS THAT had seemingly given up all their secrets are yielding new information at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
JPL geologists Robert Crippen and Ronald Blom devised a way to spot ground shifts by superimposing two satellite photos taken at different times. A team led by Paul E. Stolorz programmed the concept into a Cray T3D supercomputer and used statistical tricks to improve the resolution and spot ground movements as small as one meter.
The computer works with 100-by-100 blocks of pixels taken from larger images. If a block from the new image has to be shifted to line up with the old one, the computer records this as motion. The process is repeated thousands of times. The image here, which required 24 hours of processing on the Cray, shows dislocations in the Mojave Desert from the Landers earthquake of 1992. The color compass in the corner indicates the direction of movement. The added black lines depict known faults.
Now, the JPL team is looking for sand-dune motion on Mars. Next, it will examine Europa, a moon of Jupiter, for signs of motion that would hint at liquid water beneath its ice crust. Stolorz says a 3-D version might detect tumor growth in X-ray images.EDITED BY OTIS PORT By Peter CoyReturn to top
WHAT'S ON THE SILICON HORIZON
FOR A PEEK AT THE LONG-range future of semiconductors, the annual International Electron Devices Meeting (IEDM) is one must-go event. Held this year in San Francisco in mid-December, it left no doubt that the age of "system chips" is about here.
System chips will have all of a product's electronic circuitry squeezed onto one chip--including both logic and memory functions, which heretofore have been produced with incompatible chipmaking techniques. Engineers are bypassing old roadblocks so chips can have several times as many transistors as on all the chips in most systems today. At IEDM, researchers seemed confident of shrinking transistors by 2005 to 0.12 microns, or half the size of those on the most advanced chips. Indeed, a team from Mitsubishi Electric Corp. showed how the light from a krypton-fluoride laser can "print" 0.12-micron transistors. Look for chips to sport 4 billion or more transistors in less than 10 years.
Tomorrow's chips could spring an even bigger surprise by combining normally incompatible materials, such as silicon and gallium arsenide (GaAs). Researchers from Japan's Nagoya Institute of Technology reported that GaAs "islands" can be seeded on silicon--despite the mismatch in their crystalline structures--if the islands are very tiny. The Nagoya team thus scored a first: building GaAs light-emitting diodes (LEDs) on silicon. That sets the stage for hybrid chips that can handle both optical and electrical signals.EDITED BY OTIS PORTReturn to top
THE GIFT OF SIGHT--FROM A TOOTH
BHIMJI VARSANI JUST TRADed an eyetooth for an eye. The vision of the one-eyed grandfather from London has been deteriorating as a result of trachoma, a viral disease of the eye. Corneal transplants failed, and he went totally blind. But if all goes well, he'll see his grandchildren again next year--through his eyetooth.
Using a tooth to repair an eye may seem strange, but the dentine in teeth is more resistant than calcium in bones to body fluids. A hard material is needed to hold an artificial lens in place and maintain the eye's structural integrity.
After the tooth was removed on Nov. 27, Christopher Liu, a surgeon at Sussex Eye Hospital in Brighton, ground its root into a small rectangular plate, punched a hole in the center, and inserted a plastic lens. Then the plate was embedded in Varsani's cheek, where it will be infiltrated by tissue, because the tooth is still alive. Next year, the plate and the attached soft tissue will be stitched into Varsani's eye. This procedure was developed by Giancarlo Falcinelli, chief ophthalmologist at Rome's San Camillo Hospital. In Italy, 180 of these procedures have been performed, with a 75% success rate.EDITED BY OTIS PORT By Julia FlynnReturn to top