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Downloads without the Agonizing Wait


By late this year, surfers can look forward to dramatically faster downloads of Web pages packed with pictures, charts, and logos. The speed boost will come with the rollout of JPEG2000, an update of the JPEG compression standard that is widely used to store and transfer images. The trick, says Michael W. Marcellin, one of JPEG2000's lead developers, is its "just enough" approach.

In essence, that means the bigger the image file, the greater the benefit. JPEG2000 promises to cut download time for everyday Web images--in the range of 20 to 100 kilobytes--by a respectable 50%. "But the compression really sings with big images," says Marcellin, a professor of electrical and computer engineering at the University of Arizona.

When retrieving an image from a server, today's Web browsers try to open the whole file, no matter how big. A JPEG2000-enabled browser first checks where the pic will be displayed--or printed, or saved--and grabs a subset of the file fitted to the user's screen, printer, or hard drive. Thanks to such on-the-fly sizing, big images can be delivered upwards of 1,000 times as fast, says Marcellin. JPEG2000 offers another enhancement: the option of "lossless" compression, so that no detail is lost from the original image.

Web browsers are just the beginning. Now that the standard has been approved by the International Organization for Standardization (ISO) in Paris and made available gratis to developers, expect to see JPEG2000 in everything from digital cameras to digital copiers and printers from Eastman Kodak, Sony, Ricoh and others by the third quarter. Flaviviruses, which cause insect-borne diseases such as dengue, West Nile virus, and yellow fever, have long stumped scientists trying to understand their molecular structure. No more, say researchers at Purdue University and California Institute of Technology. In the Mar. 8 issue of Cell, they describe mapping dengue's structure, thus taking the first step toward developing a vaccine to combat the virus.

Dengue infects more than 50 million people worldwide each year and causes 24,000 deaths. Using a combination of electron microscopy and computer graphics, the Purdue-Cal Tech team developed a three-dimensional view of the virus that revealed a dimpled, golf-ball-like structure with a protective protein shell over a double layer of fatty molecules. These help shelter the disease-causing genetic material in the core until its release into the cell of a host.

The study's principal author, Purdue biologist Richard J. Kuhn, says that some of the scientists' biggest challenges were getting a large enough sample of the easily damaged virus to study, and protecting people working with it. Now that the structure has been identified, the team will try to determine how the virus fuses with the cells of its victims to spread the disease. Environmental crusader Erin Brockovich could have made good use of a new method for measuring hexavalent chromium in contaminated groundwater. Geologists from the University of Illinois at Urbana-Champaign are now able to gauge the rate at which the suspected carcinogen naturally breaks down into a less toxic form. That could help engineers determine when a major cleanup is necessary.

Chromium, used to electroplate car bumpers, among other things, is a common inorganic contaminant at hazardous waste sites. With current tests, engineers have a hard time determining how quickly the compound is changing form. The water in a tested well may be diluted by rainfall, for example. "You're trying to sample a moving target," says Thomas M. Johnson, a University of Illinois geologist. Johnson and a colleague, Andre S. Ellis, were able to get a fix on the change by measuring the ratio of heavy to light chromium in a contaminated groundwater sample. The geologists hope to test the technique on known contaminated sites. Intel and other chipmakers are hot on the trail of semiconductors that pack 1 billion transistors and switch on and off more than 1 trillion times per second. The new chips, expected in the second half of the decade, will require radical advances in manufacturing technology. As elements such as transistors and capacitors are packed more densely together, it gets harder to deposit uniform, ultrathin layers of materials to insulate the circuit lines.

ASM International, in the Dutch town of Bilthoven, has developed a form of chemical vapor deposition that lays down uniform layers just 10 to 20 atoms thick. In brief, a silicon wafer is exposed to a single gas in a purified chamber. The surface of the chip reacts with the gas, and as soon as it is saturated, the reaction stops. After the reactor is cleaned, the process can be repeated with a second gas. "It's self-limiting," says Henk de Waard, business manager for thin films. "You get a single atomic layer everywhere on the surface of the wafer, with extreme control over film thickness." ASM is taking orders from top chipmakers, with the goal of billion-transistor chips by 2005 in mind.


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