2,923 research outputs found
Dissipation and memory effects in pure glue deconfinement
We investigate the effects of dissipation in the deconfining transition for a
pure SU(2) gauge theory. Using an effective model for the order parameter, we
study its Langevin evolution numerically, and compare results from local
additive noise dynamics to those obtained considering an exponential non-local
kernel for early times.Comment: 4 pages, 2 figures, to appear in the proceedings of Strong and
Electroweak Matter (SEWM06), BNL, May 200
Quality control of GEM detectors using scintillation techniques
Non destructive quality control of microstructures at the manufacturing stage
is an important issue in the foreseen use of huge numbers of such gaseous
detectors in the future high luminosity colliders. In this work we report on
the use of the scintillation light emitted by the avalanches in GEM channels
for checking defects in the foils. The test system is described and data on the
relative efficiency of several gaseous mixtures are presented. The foil images
obtained with a low-noise CCD system are analysed and compared with the optical
images obtained with an industrial inspection system of high magnification. The
validity of this test method is established and possible extensions of its use
are discussed.Comment: 11 pages, 9 figure
Electromagnetic field evolution in relativistic heavy-ion collisions
The hadron string dynamics (HSD) model is generalized to include the creation
and evolution of retarded electromagnetic fields as well as the influence of
the magnetic and electric fields on the quasiparticle propagation. The
time-space structure of the fields is analyzed in detail for non-central Au+Au
collisions at 200 GeV. It is shown that the created magnetic
field is highly inhomogeneous but in the central region of the overlapping
nuclei it changes relatively weakly in the transverse direction. For the impact
parameter 10 fm the maximal magnetic field - perpendicularly to the
reaction plane - is obtained of order 5 for a very short time
0.2 fm/c, which roughly corresponds to the time of a maximal overlap of
the colliding nuclei. We find that at any time the location of the maximum in
the distribution correlates with that of the energy density of the
created particles. In contrast, the electric field distribution, being also
highly inhomogeneous, has a minimum in the center of the overlap region.
Furthermore, the field characteristics are presented as a function of the
collision energy and the centrality of the collisions. To explore the effect of
the back reaction of the fields on hadronic observables a comparison of HSD
results with and without fields is exemplified. Our actual calculations show no
noticeable influence of the electromagnetic fields - created in heavy-ion
collisions - on the effect of the electric charge separation with respect to
the reaction plane.Comment: 17 pages, 22 figures, title changed by editor, accepted for PR
Iroa: the international register of open abdomen. an international effort to better understand the open abdomen: call for participants
Actually the most common indications for Open Abdomen (OA) are trauma, abdominal sepsis, severe acute pancreatitis and more in general all those situations in which an intra-abdominal hypertension condition is present, in order to prevent the development of an abdominal compartment syndrome. The mortality and morbidity rate in patients undergone to OA procedures is still high. At present many studies have been published about the OA management and the progresses in survival rate of critically ill trauma and septic surgical patients. However several issues are still unclear and need more extensive studies. The definitions of indications, applications and methods to close the OA are still matter of debate. To overcome this lack of high level of evidence data about the OA indications, management, definitive closure and follow-up, the World Society of Emergency Surgery (WSES) promoted the International Register of Open Abdomen (IROA). The register will be held on a web platform (Clinical Registers (R)) through a dedicated web site: www. clinicalregisters. org. This will allow to all surgeons and physicians to participate from all around the world only by having a computer and a web connection. The IROA protocol has been approved by the coordinating center Ethical Committee (Papa Giovanni XXIII hospital, Bergamo, Italy).Actually the most common indications for Open Abdomen (OA) are trauma, abdominal sepsis, severe acute pancreatitis and more in general all those situations in which an intra-abdominal hypertension condition is present, in order to prevent the development103713sem informaçãosem informaçã
Improved semiclassical density matrix: taming caustics
We present a simple method to deal with caustics in the semiclassical
approximation to the thermal density matrix of a particle moving on the line.
For simplicity, only its diagonal elements are considered. The only ingredient
we require is the knowledge of the extrema of the Euclidean action. The
procedure makes use of complex trajectories, and is applied to the quartic
double-well potential.Comment: 20 pages, 7 figures. Revised version, accepted for publication in
Phys. Rev.
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