From: revu@ellis.uchicago.edu (Sendhil Revuluri)
Subject: Physics News Update #92 (8/19)
Summary: Second posting of PNUP to sci.physics
Keywords: physics news interesting cherry
Reply-To: revu@midway.uchicago.edu
Organization: University of Chicago
Distribution: usa
Date: Wed, 19 Aug 1992 20:55:26 GMT

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In response to the requests for "real" physics information, I am going
to post this and future "Physics News Updates" distributed by AIP
Public Information's Phillip Schewe to sci.physics.  For those who
want to receive PNUPs via email, mail pfs2@aip.org with your address
and you will be added to the distribution list.

Complaints or suggestions are welcome; please mail them to me at the
address below.


Sendhil Revuluri (s-revuluri@uchicago.edu)
University of Chicago

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PHYSICS NEWS UPDATE
A digest of physics news items prepared by Phillip F. Schewe, AIP
Public Information
Number 92   August 19, 1992

THE LANDSCAPE OF DNA MAY BE FRACTAL.  Several studies of DNA reveal
unexplained relationships between nucleotides distant from each other.
A Rockefeller/Tokyo team of scientists found such correlations in the
genes regulating blood coagulation (Europhysics Letters, 7 Feb).
Researchers at Boston University transformed sequences of nucleotide
into a series of "random walks" and discovered correlations over many
scales--- 1000, 10000, and 100000 nucleotide---suggesting a fractal
pattern (Nature, 12 Mar.).  Self-similarity on a scale of 50 million
nucleotides has showed up in a study at IBM (Phys. Rev. Lett., 22
June).  Long-range correlations did not appear in DNA sequences where
introns, little-understood intervals of apparently noncoding DNA, were
absent, a fact which had frustrated earlier attempts to find
correlations in bacterial DNA which did not contain introns.
(Science, 7 August 1992.)

THE ELECTRICAL CHARGE OF ANTIPROTONS AND POSITRONS has been studied
using data from cyclotron- frequency experiments (which monitor the
behavior of particles in a magnetic field) comparing protons with
antiprotons and electrons with positrons, as well as spectroscopic
measurements of short- lived states containing antimatter, such as
positronium and antiprotonic atoms.  Richard Hughes of Los Alamos and
B.I.  Deutch of the University of Aarhus in Denmark have calculated
that the charges of the positron and electron are equal to about one
part in 10**8, while the charge of the antiproton equals that of the
electron to about one part in 10**5 (Phys. Rev. Lett., 27 July).  The
precision of these calculations would improve if researchers could
study antihydrogen, an atom consisting entirely of antimatter.
(Science News, 15 August 1992.)

PHOTONS FROM SONOLUMINESCENCE MAY PEAK IN THE ULTRAVIOLET.
Sonoluminescence (SL) is a phenomenon in which sound waves create
bubbles in a sample of water and cause them to oscillate.  The excited
bubbles in turn emit light.  Last year, Seth Putterman (213-825-2269)
and his group at UCLA discovered that the light pulses were very
short, only 50 psec, and that the conversion of sound energy into
light energy represented in effective energy concentration of 12
orders of magnitude.  Now the UCLA scientists have studied the spectra
of SL photons and found that if a peak exists it must be at an energy
above 6 eV; detection of photons with energies above this value could
not be calibrated.  The UCLA researchers believe SL can be used for
producing a broadband light source in the wavelength range of 190-750
nm.  (Robert Hiller et al., 24 August, Physical Review Letters.)

"SEAGEL" IS THE LIGHTEST SOLID.  Produced by Robert Morrison at
Lawrence Livermore National Lab, Seagel is made of agar from kelp, and
contains only 40 to 50 mg of material per cubic centimeter of solid.
(New Scientist, 15 August 1992.)

PHYSICS NEWS UPDATE will recess for three weeks while the
editor explores the physics of Yosemite and Sequoia National
Parks.

-- 
Sendhil Revuluri (s-revuluri@uchicago.edu)
University of Chicago