Science, engineering and technology newstips

Science, Engineering and Technology News Tips
University of California, Davis
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* Web surfing at the speed of light
* Building better optical networks
* Taking manufacturing to the microscale
* Physicists hot on trail of superconductors
* Ticks carry 'cat scratch' bacteria
* Math professor wins Guggenheim Fellowship
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WEB SURFING AT THE SPEED OF LIGHT

The future of the Internet will be optical, according to engineer Ben Yoo at the University of California, Davis. Yoo is leading a team to build a trial optical Internet system, to be tested on the UC Davis campus later this year.

Optical networks use light pulses to transmit data instead of electrons. Most long-distance communications systems already use fiber-optic cable, but the light signals are turned back into electronic signals when they reach routers and switching points. These optical-to-electronic connections are a major bottleneck.

The UC Davis team is developing an all-optical router, which can switch "packets" of data made of light pulses in the same way that an electronic router handles data packets.

Existing optical switches use tiny mirrors to redirect light pulses. Yoo's router takes a different approach, switching light pulses by changing their wavelength. This technology potentially allows much faster switching than mirror-based technologies, said Yoo.

The optical Internet could achieve speeds of 10 terabits (10 million megabits) per second, Yoo said. Importantly, latency -- the length of time a data packet waits in a router before being sent on its way -- is much lower than that of electronic routers, he said. Packets spend a brisk 100 nanoseconds in the optical router, while lazing for several microseconds in the best available electronic routers.

The basics of Yoo's optical router were presented at the Optical Fiber Communication 2001 conference in Anaheim last month.

Future expansion of the test network to UC Berkeley, UC Santa Cruz and UC Merced is included in the proposed Center for Information Technology Research in the Interest of Society (CITRIS). Funding for CITRIS was included by Gov. Gray Davis in the proposed state budget for 2001-2002.

More information: http://sierra.ece.ucdavis.edu.

Media contacts: Ben Yoo, Electrical and Computer Engineering, (530) 752-7063, [email protected]; Andy Fell, News Service, (530) 752-4533, [email protected].

BUILDING BETTER OPTICAL NETWORKS

The best way to build optical communication networks is the object of research by computer scientist Biswanath Mukherjee and electronic engineer Jonathan Heritage of the University of California, Davis.

"We can create gadgets, but this is useless without understanding network architecture," said Mukherjee.

Networks require repeaters and cross-connects that allow long-distance signals to pass through a junction point, while local traffic splits off. Mukherjee and Heritage use a computer modeling approach to work out how cross-connects should be positioned.

"The question is, when should we stay in the optical domain and when should we go back to electronics to repair the signal?" said Heritage.

To multiply the number of signals carried by a single fiber, engineers use wavelength division multiplexing (WDM). Each signal is allocated a slightly different wavelength of light. The UC Davis researchers are studying how best to assign wavelengths to signals, how to handle multiple wavelengths, and the best way to route the WDM signals across networks.

Optical communications depend on advances in optics, electronic engineering, computer science and software development, said Mukherjee. The greatest payoff would come from merging the best of each field, rather than focusing on one area, he said.

Mukherjee teaches a course in optical networks at UC Davis and has authored a textbook on the subject. He is a past chair of the Department of Computer Science and has acted as consultant for a number of communications companies. Heritage is currently chair of the Department of Electrical and Computer Engineering at UC Davis.

Media contacts: Biswanath Mukherjee, Computer Science, (530) 752-4826, [email protected]; Jonathan Heritage, Electrical and Computer Engineering, (530) 752-2455, [email protected]; Andy Fell, News Service, (530) 752-4533, [email protected].

TAKING MANUFACTURING TO THE MICROSCALE

Applying manufacturing methods for computer chips to make tiny mechanical devices with moving parts is the objective of Norman Tien, professor of engineering at the University of California, Davis.

"It's about taking chip technology to the mechanical and optical domains," said Tien.

Tien works on microelectrical mechanical systems, or MEMS. Some MEMS are already in commercial use, for example as motion sensors that trigger airbags in cars. Other applications are in miniaturization of optical and wireless communication systems, and in building chips that can perform chemical reactions on a miniature scale.

Tien's laboratory has developed a miniature motor that can be built on a chip and used to move a mirror less than 1/100 of an inch, or 1/5 of a millimeter, across. These mirrors form the core of an all-optical switch box for use in optical communications systems. The switch box would use arrays of these moving micromirrors to control light pulses from fiber-optic cables. This would avoid having to convert optical pulses to electronic signals, switch them, and then turn them back into light pulses, said Tien.

Such an optical switch box could potentially have hundreds or thousands of input and output connections, compared to 16 each for electronic switching boxes, he said.

Devices using micromirror technology, such as some electronic projectors, are already available, said Tien.

Tien's group is also working on miniaturizing components for cell phones. Currently, some components for tuning and receiving radio waves cannot be put on chips, increasing the size of devices. Miniaturized, on-chip components will be needed to make wearable communications devices feasible, he said.

Note: A picture of the micromirror and motor is available. Contact Andy Fell for details.

Media contacts: Norman Tien, Electrical and Computer Engineering, (530) 754-9267, [email protected]; Andy Fell, News Service, (530) 752-4533, [email protected].

PHYSICISTS HOT ON TRAIL OF SUPERCONDUCTORS

January's discovery of high-temperature superconductivity in magnesium diboride, a common laboratory compound, has set scientists scrambling to understand the phenomenon, said physicist Warren Pickett of the University of California, Davis. Using a computer model, Pickett and graduate student Joonhee An have come up with an explanation of how this superconductivity occurs.

Superconductors have essentially no resistance to electrical current. They are used to make powerful magnets, used for example in medical magnetic resonance imaging (MRI) machines. Their use is limited by the need for cooling to almost absolute zero (less than minus 450 F) with liquid helium.

In 1986, scientists discovered that some ceramic compounds became superconductors at higher temperatures, around minus 390 F. While this is still pretty cold, this jump in operating temperature represented a major advance. However, these materials were expensive to produce and difficult to make into wire, said Pickett.

Theoretically, there's no reason that room temperature superconductivity should be impossible, he said.

On Jan. 10 this year, Japanese scientist Jun Akimitsu announced that magnesium diboride became superconducting at minus 389 F. As well as being relatively cheap, magnesium diboride is a metal which seems to have encouraging properties for some applications, said Pickett.

After hearing of the discovery, Pickett's lab began to model the behavior of magnesium diboride crystals, which are made up of alternating layers of magnesium and boron atoms. They found that while the atoms in each layer are held together by strong chemical bonds, the structure and composition of magnesium diboride makes these bonds act as if they were metallic bonds. These metallic bonds contribute to the superconductivity of magnesium diboride.

"We need to look at more layered materials like this, that are metallic or that can be made metallic. There's no reason we can't find materials that are still better superconductors," said Pickett.

Pickett and An's paper is to be published in Physical Review Letters. A preprint is available on the Internet.

Media contacts: Warren Pickett, (530) 752-0926, [email protected]; Andy Fell, (530) 752-4533, [email protected].

TICKS CARRY 'CAT SCRATCH' BACTERIA

Ticks collected in Santa Clara County, California, carried Bartonella bacteria that infect cats, dogs, cattle and sometimes humans, according to a new study. Bartonella henselae, the agent of "cat scratch" disease, usually causes a mild fever in humans but can be serious or fatal in patients with a weakened immune system.

"At the least we can say that ticks carry Bartonella DNA and could be potential vectors," said Bruno Chomel, professor of veterinary medicine at the University of California, Davis, and one of the authors of the study.

Chomel and graduate student Chao-Chin Chang, working with colleagues from the Santa Clara County Department of Health Services, collected ticks and tested them for Bartonella DNA. Almost 20 percent of the ticks collected were infected with Bartonella species found in cats, dogs, cattle and other animals.

Although there is no clear evidence that humans can develop the disease from tick bites, there were some reported cases of cat scratch disease where the only risk factor was a tick bite, said Chomel.

More research is needed to find out the role of ticks and other animals in transmitting these bacteria between animals and to humans, Chomel said.

The study is published in the April issue of the Journal of Clinical Microbiology.

Media contacts: Bruno Chomel, School of Veterinary Medicine, (530) 752-8112, [email protected]; Andy Fell, News Service, (530) 752-4533, [email protected].

MATH PROFESSOR WINS GUGGENHEIM FELLOWSHIP

Art Krener, professor of mathematics at the University of California, Davis, has been awarded a Guggenheim fellowship for his work on "Normal forms and bifurcation of control systems." Control systems are widespread in the modern world, for example allowing us to steer cars, fly airplanes, and run factory assembly lines. Bifurcations are "forks in the road" where a system suddenly changes from one state to another, such as an engine stalling when the fuel supply is reduced.

"Art is one of the giants of the field," said Alan Laub, former dean of engineering at UC Davis. Krener's groundbreaking research had brought this technology to the point where it could be used by design engineers, Laub said.

The Guggenheim Foundation's fellowship program provides recipients with the opportunity to pursue their work in the manner they choose for six to 12 months.

Krener will use the award for travel and to begin work on a new theory to explain bifurcation in complex control systems. The idea grew out of a research project on jet engines sponsored by the U.S. Air Force and involving collaborators at several campuses and institutes.

"I realized that this work had wider applicability, and that we needed a general theory," said Krener. He expects to spend several years working out the new theory.

Krener has worked at UC Davis since 1971, after completing his Ph.D. at UC Berkeley. He has been a visiting scientist at NASA's Ames Research Center and at UC Berkeley. He is a Fellow of the Institute of Electronic and Electrical Engineers, and a member of the Society for Industrial and Applied Mathematics and of the American Mathematics Society.

More information: http://www.gf.org.

Media contacts: Art Krener, Mathematics, (530) 752-3185, [email protected]; Andy Fell, News Service, (530) 752-4533, [email protected].