Number 136, July 9, 1993 by Phillip F. Schewe and Ben Stein
MOLECULAR-LEVEL "AND" LOGIC-GATE behavior has been observed
by scientists at Queen's University, Belfast. In this case special polymer
molecules are made to fluoresce strongly (constituting a sort of output
signal) only when two hydrogen or two sodium ions (constituting the input)
bind to each of two "recognition" sites on the molecule. This
process cannot yet be employed in a logical device, however, because the
necessary molecular circuitry ("wires" in the form of conducting
molecules) for systematically conveying input signals---in the form of
ions---to the molecule has not been developed. Meanwhile, certain forms
of the receptor molecule can be used to monitor ion concentrations in some
solutions. (A. de Silva et al., Nature, 1 July 1993.)
THE ANNUAL PERSEID METEOR SHOWER will be particularly intense this year
because Comet Swift-Tuttle, the parent comet whose tail leaves behind particles
that can potentially rain down on Earth each August, reached its closest
approach to the Sun during its 130-year orbit last fall, at which time
the Sun helped to boil off a new supply of candidate meteoroids. Peaking
on August 11-12, the shower will consist of tiny objects striking our atmosphere
at velocities up to 72 km/sec (160,000 mph). Their visible streaks (best
viewed after midnight) will appear to be coming from a single point in
the sky (the "radiant"), but actually the shower objects approach
the atmosphere---where they disintegrate at altitudes of about 60 or 70
miles---along parallel paths. (Astronomy, August 1993.)
THE ADVANCED LIGHT SOURCE (ALS) , the 1.5 GeV synchrotron radiation machine
at LBL, is almost ready for doing physics research. In recent tests the
number of circulating electrons exceeded the design current of 400 mA.
When undulators meant to enhance the electrons' synchrotron emission are
installed, the ALS should provide high-brightness light beams in the vacuum
ultraviolet and soft x-ray wavelength ranges. (CERN Courier, June 1993.)
THE TWO DETECTOR FACILITIES PLANNED FOR THE LARGE HADRON COLLIDER (LHC)
are to be called ATLAS and CMS. The LHC itself has not yet been approved
for construction at the CERN lab in Geneva; that decision will be made
in December. As with the detector groups at LHC's higher-energy rival,
the SSC (whose fate will presently be decided in the US Congress), ATLAS
and CMS are supported by mammoth retinues: respectively, 800 and 400 physicists
from a score of nations. (Physics World, July 1993.)
THE JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY (JVST) will soon be issued
on compact disks (CD-ROM) readable on any CD-equipped PC or Mac computer.
The first major physics or technology journal to appear in this format,
JVST will continue also to be printed on paper. JVST, a monthly journal
amounting to about 7000 pages a year, is published by the American Vacuum
Society. (For more information, contact AVS at 212-661-9404.)
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