Text 793, 73 rader
Skriven 2006-06-28 20:03:11 av Herman Trivilino (1:106/2000.7)
Ärende: PNU 782
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PHYSICS NEWS UPDATE
                                        
The American Institute of Physics Bulletin of Physics News
Number 782   June 27, 2006  by Phillip F. Schewe, Ben Stein, and
Davide Castelvecchi
                                                                
MAKING RADIOACTIVE SCORPION VENOM THERAPY SAFE.  At this week's
meeting of the Health Physics Society in Providence, researchers
will describe how they have helped establish the safety of a
surprising new treatment for an aggressive, essentially incurable
malignant cancer called high-grade brain glioma, diagnosed in over
17,000 people in the US every year.  The treatment is based on the
discovery that the venom in the yellow Israeli scorpion contains a
protein that binds selectively to the glioma cells. The procedure
uses a compound called TM-601, a synthetic version of the venom
protein attached to a radioactive substance called I-131 that kills
the glioma cells.  When injected into the bloodstream, the
radioactive scorpion venom protein travels to the brain and attaches
to the glioma cells, with the I-131 releasing radiation that kills
the cells.
Describing the second sequence of phase II clinical trials involving
human patients, health physicist Alan M. Jackson (AlanJ@rad.hfh.edu)
of the Henry Ford Health System in Detroit will report that he and
his colleagues recently established safe procedures for the
therapy.  Patients in the trial received a radioactive dose of 40
millicuries (mCi) per week.  This dose is not tremendously high
compared to a thyroid cancer treatment, in which patients receive up
to 200 mCi of I-131 in a single treatment.  As Jackson determined,
patients could safely return home several hours after the treatment,
as their families would not be exposed to any more radiation than is
typical with a thyroid cancer patient returning home after the
procedure.  And according to a separate group's study of the first
sequence of phase II trials, patients receiving up to 40 mCi of
weekly dose did not show evidence of any adverse reactions
attributable to the radiation.  The phase II trial at Henry Ford
involves 3 patients, with a total of 54 patients across the US
currently in investigational trials for the therapy. (Paper
WAM-B.11, Wednesday, June 28, 2006; meeting website at
http://hps.org/newsandevents/meetings/meeting5.html;
http://www.transmolecular.com/pdfs/FiveashPR_ASCOVersion.pdf )

WARM DENSE GOLD. Physicists at Lawrence Livermore Lab have used
intense light to convert a small solid gold target into a plasma of
electrons and positive ions. In the instant before the sample flies
apart the physicists are able to record some surprising results. The
most important finding is that even at extreme conditions of high
energy density (10^7 J/kg), the gold metal still retains the band
structure exhibited  by all metals---the allowed electron energies
are not continuous but fall into certain allowed energy bands. With
light from a femtosecond laser falling on the sample, the Livermore
scientists achieve the highest isochoric (meaning under conditions
of constant density) energy density ever observed for a solid---10^7
J/kg. According to one of the researchers, Andrew Ng
(ng16@llnl.gov), who is the scientific director of Livermore's
Jupiter Laser Facility, expressing the energy density in terms of
energy per unit mass, rather the customary energy per unit volume,
gives a more direct sense of the excitation energy
being invested in each atom or molecule. (Higher energy densities
have been achieved by imploding a target with laser light or a
nuclear explosion, but the new result is the highest for a sample at
its original volume.) Furthermore, this experiment achieves a record
for heating rate---exceeding 10^17 K/sec---for the electrons in the
solid; the ions forming the lattice of the solid are heavier and
warm up at a much slower rate.  This work can be considered as part
of an emerging new subject, "warm dense matter," at the crossroads
between condensed matter physics and plasma physics. This research
area, related to another topic called "high energy density physics,
is also of interest to workers in disciplines such as high pressure
science, planetary science, geophysics, and shock compression. (Ping
et al., Physical Review Letters, 30 June 2006)

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