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[Written by individuals at the American Institute of Physics and
merely posted by me, so respond to <pfs2@aip.org> or other
references below.  Always posted here on sci.research; usually
crossposted to an eclectic and hopefully appropriate selection of
other newsgroups, with followups directed here. Back issues may be
ftp'd from NIC.HEP.NET, along with FYI and the American Physical
Society news/opinion column WHAT'S NEW.  Astro folks should note
that the new moderated group sci.astro.research will receive all
PNUP's, or at least the astro-relevant ones, directly from AIP.
Enjoy! -jc]

PHYSICS NEWS UPDATE
A digest of physics news items by Phillip F. Schewe, American
Institute of Physics
Number 187  July 11, 1994                   physnews@aip.org

A CIRCUMSTELLAR DUST RING, made from asteroid debris, may
exist and might be centered at a radius just outside Earth's orbit
around the sun.  Astronomers at the University of Florida reach this
conclusion using a combination of numerical simulations of dust
particles migrating from the asteroid belt (between Mars and Jupiter)
in toward the sun and using observations made by the Infrared
Astronomical Satellite (IRAS) of features in the zodiacal cloud, the
thin fog of dust pervading the inner solar system.  The Florida
scientists suggest that the resonance effects that shuttle dust into and
out of the heliocentric ring may also be important in building planets
in star systems (such as Beta Pictoris) with circumstellar dust disks.
(Stanley F. Dermott et al., Nature, 30 June 1994.)

THE INTERGALACTIC MEDIUM (IGM) MAY HAVE BEEN
DETECTED, at least that part of it consisting of singly ionized
helium.  Using the Hubble Space Telescope (HST), a Dutch-British-
French-US team of astronomers have sampled the light coming from
the quasar Q0302-003 (redshift of 3.286).  They notice that ultraviolet
light at a wavelength of 304 angstroms is being absorbed along the
way, supposedly by the singly ionized helium making up part of the
IGM.  (Another presumed IGM component, singly ionized hydrogen,
cannot be observed since, consisting of bare protons, it exhibits no
atomic transitions.)  Using the quasar approach to inferring the
presence of the IGM is difficult because the quasar must be far away,
so that the ultraviolet radiation can be redshifted into a range that can
be detected by HST, and because it is rare for such a quasar not to
lie behind several foreground neutral-hydrogen clouds, which could
also absorb the ultraviolet.  (P. Jakobsen et al., Nature, 7 July 1994.)

THREEFOLD INCREASED DETAIL IN THE STRUCTURE OF A
BIOMOLECULE was obtained when researchers applied a
combination of several powerful techniques to x-ray crystallography.
Wladek Minor (317-494-0879) of Purdue University and his
colleagues used the Cornell High Energy Synchrotron Source to
determine the atomic structure of crystallized L-1 lipoxygenase
enzyme, a protein involved in polyunsaturated fatty acid metabolism
in both mammals and plants.  The synchrotron radiation's high
intensity, combined with a special CCD detector, allowed the
researchers to obtain data rapidly and with a very high signal-to-noise
ratio.  Cooling the crystal to near-liquid nitrogen temperatures
preserved the crystalline order for hours of synchrotron beam
exposure, permitting three times the number of observations than the
best previous data set for this protein. Analysis of the data yielded
crystal structure information with a resolution of 1.4 Angstroms, the
best yet for such a large protein (containing 839 amino acids).  Minor
says this combination of techniques can be applied to learn new
structural details of other proteins and viruses.  (Paper at the meeting
of the American Crystallographic Association in Atlanta, June 27-July
1.)

PHYSICS NEWS UPDATE will presently recess for three weeks.