August 13, 1999
For more information on these science news and feature story tips,
please contact the public information officer at the end of each item
at (703) 292-8070. Editor: Cheryl Dybas Contents of this News Tip:
Two National Science Foundation (NSF)-funded scientists have invented
a device that could simplify the study of cells by isolating the molecules
that inhabit cell walls. The unusual apparatus harnesses thermal noise
to drive the sorting process, rather than relying on conventional energy
sources.
"The ability to separate membrane-associated molecules is extremely
important," says chemist Steven Boxer of California’s Stanford University, "because
they play a vital role in the life of the cell and have proven exceptionally
difficult to purify, characterize and study."
Boxer and colleague Alexander van Oudenaarden developed the new sorting
system, and report on its design and operation in the August 13 issue
of the journal Science. Unlike conventional separation techniques,
the new system can separate membrane molecules in their native environment
and do so continuously, rather than in batches. Because it relies on fabrication
techniques developed in the microelectronics industry, the device should
be inexpensive to manufacture in volume and relatively simple to modify
for specific purposes, Boxer says. [Cheryl Dybas]
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In 1918, Albert Einstein predicted the existence of gravitational waves
in his general theory of relativity, but so far, scientists have only
found indirect evidence of their existence. The future NSF-funded Laser
Interferometer Gravitational-wave Observatory (LIGO) will be one of the
most sensitive instruments ever designed to directly detect gravitational
waves reaching the earth from outer space.
In LIGO, laser beams travelling between mirrors inside 4-kilometer vacuum
tubes will be slightly offset when the mirrors are hit with gravitational
waves. These instruments will be able to measure displacements smaller
in size than the diameter of a proton.
Researchers recently analyzed data obtained with a small (40-meter-long
vacuum tubes) LIGO prototype at the California Institute of Technology.
They will publish their findings in the August 23 Physical Review
Letters. The scientists looked for gravitational-wave "chirps" emitted
by binary neutron stars within our galaxy -- two stars spiraling together
and coalescing at the end of their lives. The team was able to determine
an upper limit for the rate of such events occurring within our galaxy
no more than once every two hours. Future LIGO detectors should be able
to detect similar events that have occurred in far away galaxies, at rates
as infrequent as once every million years.
Construction of the LIGO detectors at Hanford, Washington, and Livingston,
Louisiana, is almost complete; they are expected to be operational by
the end of 2001. [Amber Jones]
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Recent studies have found that in the United States, women earn as little
as 71-74 cents on every dollar earned by men. This is not quite the case
in the engineering profession, says a newly published NSF Issue Brief,
which asks in its title, "How Large is the Gap in Salaries of Male and
Female Engineers?"
In engineering, the salary gap was as small as 13 percent in 1995, based
upon an NSF survey covering employed full-time engineers, which included
1.5 million college graduates of all ages in 16 engineering occupations.
Controlling for years of experience and other variables in a process called
multivariate regression analysis, the gender gap in salaries actually
shrinks to as little as three percent or less.
The brief also noted that unmeasured factors like time out of the workplace
might help explain the remaining 2-3 percent of the difference not explained
by the studied variables. [Bill Noxon]
For the entire issue brief, see: http://www.nsf.gov/sbe/srs/issuebrf/ib99352.htm Top of Page
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