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Skriven 2004-12-01 17:38:57 av Herman Trivilino (1:106/2000.7)
Ärende: PNU 711
===============
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 711 December 1, 2004
by Phillip F. Schewe, Ben Stein
                        
THE TOP PHYSICS STORY FOR 2004.  For us it was the detection of spin at the
single-electron level using a cantilever device---a combination of MRI and AFM
technologies---known as a magnetic resonance force microscope
(http://www.aip.org/pnu/2004/split/692-1.html).  Other top physics stories
included the following: the detection of large galaxies located at a very early
period in the history of the universe
(http://www.aip.org/pnu/2004/split/668-1.html); reports of a "supersolid," a
superfluid in solid form (http://www.aip.org/pnu/2004/split/669-1.html;
http://www.aip.org/pnu/2004/split/699-2.html); progress in the pursuit of
quark-gluon plasma in heavy-ion collisions
(http://www.aip.org/pnu/2004/split/669-2.html); progress in getting fermi atoms
to form superfluids (http://www.aip.org/pnu/2004/split/671-1.html,
http://www.aip.org/pnu/2004/split/681-1.html); evidence, not yet confirmed, for
element 115 (http://www.aip.org/pnu/2004/split/672-1.html); new support for an
accelerating cosmic expansion (http://www.aip.org/pnu/2004/split/675-1.html);
lensing of microwaves using a flat panel of left-handed material
(www.aip.org/pnu/2004/split/675-2.html); the discovery of a planet-like object,
Sedna, the most distant object observed in the solar system
(http://www.aip.org/pnu/2004/split/677-1.html); the first pure-carbon magnet,
made from carbon nanofoam (http://www.aip.org/pnu/2004/split/678-1.html);
quantum entanglement of an atom and a photon
(http://www.aip.org/pnu/2004/split/680-2.html); parity violations in
electron-electron scattering (http://www.aip.org/pnu/2004/split/682-2.html);
persistent holes appearing in a shaken fluid
(http://www.aip.org/pnu/2004/split/684-3.html); amorphous steel
(http://www.aip.org/pnu/2004/split/689-2.html); one-dimensional water
(http://www.aip.org/pnu/2004/split/689-1.html ); radioac
tive lifetime for an element is altered by enclosure in a buckyball
(http://www.aip.org/pnu/2004/split/700-2.html);
(http://www.aip.org/pnu/2004/split/689-1.html); five-photon entanglement
(http://www.aip.org/pnu/2004/split/690-2.html); Cassini arrives at Saturn
(http://www.aip.org/pnu/2004/split/690-3.html);
optical Hall effect (aip.org/pnu/2004/split/693-1.html); 3D medical imaging
with neutrons (http://www.aip.org/pnu/2004/split/694-1.html); acoustic electric
generator (http://www.aip.org/pnu/2004/split/695-2.html); smallest atomic clock
(http://www.aip.org/pnu/2004/split/698-1.html); CERN's 50th anniversary
(http://www.aip.org/pnu/2004/split/701-3.html; an antenna for visible light
(http://www.aip.org/pnu/2004/split/701-1.html); the 2004 Nobel physics prize
going to three of the pioneers of the theory of quantum chromodynamics
(http://www.aip.org/pnu/2004/split/703-1.html); some of the network physics
behind book bestsellers (http://www.aip.org/pnu/2004/split/709-1.html);
spintronic Hall effect (Science online, Nov 11); a nuclear experiment producing
1400 different isotopes (http://www.aip.org/pnu/2004/split/710-1.html).

SOFT-METAL WHISKERS, tiny metallic protrusions that grow like hair from soft
metals, are a problem that can cause electronic short circuits leading, in some
cases, to the failure of heart pacemakers, avionic relays, and satellites. 
What to do with the unwanted whiskers---and, in the first place, understanding
how they form---is a problem that's been around for fifty years.  Now,
researchers at Drexel University have arrived at what they think is an
explanation for the cause of whiskers and a potential method for alleviating
them.  Basically, the whiskers form because of reactions between oxygen and the
soft metal such as tin or indium. The reaction results in a volume increase
that pushes the whiskers out.  The whiskers that form do not have to break off
in order to be troublesome; sometimes they cause mischief merely by bridging
two neighboring electronic pathways that are supposed to be insulated from each
other.  The Drexel scientists believe that an oxygen-barrier coating on
pertinent surfaces should prevent whiskers from developing.
(Barsoum et al. Physical Review Letters, 12 November 2004;
contact Elizabeth Hoffman, enh22@drexel.edu)

NON-US FIRST-YEAR PHYSICS GRAD STUDENTS at US universities are fractionally
fewer than they used to be.  Rising pretty steadily over the past 30 years to a
high in 2001 of 53% among first-year physics graduate students, the foreign
fraction dropped to 46% in 2003.  The total number of first year students (US
plus foreign) rose to 3076, the largest number since 1994.  Who sends the most
physics grad students to US departments?  China accounts for 29% of the first
year students in 2003, the India/Pakistan/SriLanka/Nepal/Bangladesh grouping
accounted for 16%, Western Europe 13%, and Eastern and Central Europe 12%. 
(More information on the reason for the foreign fall-off, on sub-discipline
choices, career expectations, fraction of women, sources of financial support,
and so forth, can be gotten from the AIP report "Graduate Student Report:
First-Year Physics and Astronomy Students in 2002 and 2003." stats@aip.org;
contact Patrick Mulvey, 301-209-3070; www.aip.org/statistics.)

***********
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 * Origin: Big Bang (1:106/2000.7)