05 October 2005
Laser amplifier slows light at room temperature
A research team led by Connie Chang-Hasnain, professor of electrical engineering and computer sciences, has created a device that uses a laser amplifier to slow the speed of light more than one-million-fold. Building upon work completed one year ago in which researchers slowed light by a factor of 31,000 times, or 6 miles per second, the team clocked the speed of light at 245 meters per second, or three-quarters the speed of sound in air. Moreover, they did this at room temperature; last year's success required temperatures as low as 10 degrees Kelvin.
In optoelectronics, adjusting the speed of light is part of an effort to overcome a bottleneck in optical communications. Optical signals speed along fiber networks, but are then jammed as they hit an intersection, or router. At these intersections, light signals are converted to slower-moving electronic data to be directed to the correct path before being switched back to light, a process known as optical-electronic-optical (OEO) conversion.
The researchers hope eventually to freeze light in its tracks, which would open doors to a world of optical memory and storage.
- Sarah Yang
Health survey suggests extending insurance benefits to parents
Extending health insurance for low-income children to their parents may help improve these children's access to a regular source of care as well as reduce perceived discrimination and breaks in coverage, according to a new study by professor of maternal and child health Sylvia Guendelman and other Berkeley researchers.
The findings come three years after California legislators approved the expansion of Healthy Families, the state's public-health-insurance program for those 18 and under, to parents of eligible children. The expansion was never implemented, due to lack of funding.
Using data from the 2001 California Health Interview Survey, the researchers analyzed the responses from 5,521 low-income parents whose children were eligible for public health insurance. Not surprisingly, they found that children in families with no health coverage had higher odds of lacking a usual source of care, of not having seen a dentist within the previous two years, and of not seeing a doctor within the previous year, compared with children with child-only insurance and with children with an insured parent.
When comparing children in family coverage and child-only coverage groups, the researchers found that those in child-only coverage families were more likely to experience breaks in insurance coverage in the past year, to lack a usual source of care, and to perceive discrimination when receiving care.
"Those with child-only coverage tend to be kids from immigrant, predominantly Latino, families who seek care in the public sector," said Guendelman. "The public sector may be more overburdened and less available to offer care to these families, which may also have fewer resources to navigate the health-care system."
Solving the mystery of short gamma-ray bursts
An international team of scientists has obtained the best evidence yet that short-duration gamma-ray bursts are caused by the collision of two compact stars. The team, which includes Kevin Hurley, senior space fellow at Berkeley's Space Sciences Laboratory, will announce its results in the Oct. 6 issue of the journal Nature.
The breakthrough burst came on July 9 from the constellation of Grus (the crane) in the southern sky, and lasted only one-tenth of a second. The burst was captured by HETE-2, a spacecraft launched in 2000 by an international collaboration involving the United States, Japan, France, and other partners.
"That was the clue we were waiting for," said Garrett Jernigan, a research physicist at the laboratory. "Bursts seem to come mainly in two varieties - the long ones, which last about 20 seconds, and the short ones, which last a few tenths of a second. It's the short ones that have been puzzling us."
Evidence has mounted over the years that the longer bursts are caused by the collapse of massive stars in distant gal