1,558 research outputs found
Heat Bath Particle Number Spectrum
We calculate the number spectrum of particles radiated during a scattering
into a heat bath using the thermal largest-time equation and the
Dyson-Schwinger equation. We show how one can systematically calculate
{d}/{d\omega} to any order using modified real time
finite-temperature diagrams. Our approach is demonstrated on a simple model
where two scalar particles scatter, within a photon-electron heat bath, into a
pair of charged particles and it is shown how to calculate the resulting
changes in the number spectra of the photons and electrons.Comment: 29 pages, LaTeX; 14 figure
Dynamical Symmetry Breaking in Planar QED
We investigate (2+1)-dimensional QED coupled with Dirac fermions both at zero
and finite temperature. We discuss in details two-components (P-odd) and
four-components (P-even) fermion fields. We focus on P-odd and P-even Dirac
fermions in presence of an external constant magnetic field. In the spontaneous
generation of the magnetic condensate survives even at infinite temperature. We
also discuss the spontaneous generation of fermion mass in presence of an
external magnetic field.Comment: 34 pages, 8 postscript figures, final version to appear on J. Phys.
Free Energy of an SU(2) Model of (2+1)-dimensional QCD in the Constant Condensate Background
Gluon and quark contributions to the thermodynamic potential (free energy) of
a (2+1)-dimensional QCD model at finite temperature in the background of a
constant homogeneous chromomagnetic field H combined with A_0 condensate are
calculated. The role of the tachyonic mode in the gluon energy spectrum is
discussed. A possibility of the free energy global minimum generation at
nonzero values of H and A_0 condensates is investigated.Comment: LaTeX 2e, 14 pages, 6 eps figures, some miscalculations were
correcte
THERMAL EFFECTS ON THE CATALYSIS BY A MAGNETIC FIELD
We show that the formation of condensates in the presence of a constant
magnetic field in 2+1 dimensions is extremely unstable. It disappears as soon
as a heat bath is introduced with or without a chemical potential. We point out
some new nonanalytic behavior that develops in this system at finite
temperature.Comment: 10 pages, plain Te
Enhancement of bulk second-harmonic generation from silicon nitride films by material composition
We present a comprehensive tensorial characterization of second-harmonic
generation from silicon nitride films with varying composition. The samples
were fabricated using plasma-enhanced chemical vapor deposition, and the
material composition was varied by the reactive gas mixture in the process. We
found a six-fold enhancement between the lowest and highest second-order
susceptibility, with the highest value of approximately 5 pm/V from the most
silicon-rich sample. Moreover, the optical losses were found to be sufficiently
small (below 6 dB/cm) for applications. The tensorial results show that all
samples retain in-plane isotropy independent of silicon content, highlighting
the controllability of the fabrication process.Comment: 4 pages, 3 figures, 2 tables; Re-submitted to Optics Letter
Generalised chiral QED2 : Anomaly and Exotic Statistics
We study the influence of the anomaly on the physical quantum picture of the
generalized chiral Schwinger model defined on the circle. We show that the
anomaly i) results in the background linearly rising electric field and ii)
makes the spectrum of the physical Hamiltonian nonrelativistic without a
massive boson. The physical matter fields acquire exotic statistics . We
construct explicitly the algebra of the Poincare generators and show that it
differs from the Poincare one. We exhibit the role of the vacuum Berry phase in
the failure of the Poincare algebra to close. We prove that, in spite of the
background electric field, such phenomenon as the total screening of external
charges characteristic for the standard Schwinger model takes place in the
generalized chiral Schwinger model, too.Comment: LATEX file, 36 pp., to appear in Phys.Rev.
Back grating optimization for light trapping in thin-film quantum dot solar cells
The work presents the design of a diffraction back grating for light-trapping in thin-film GaAs-based quantum dot solar cells. Uni-periodic and bi-periodic gratings made of off-theshelf almost transparent dielectric materials routinely used in photolithography are considered. Gratings are wave-optics simulated by rigorous coupled wave analysis. Optimizing the shape and geometrical aspect ratio of the grating, almost quadrupled photocurrent from quantum dots is demonstrated
Actions to improve documented pain assessment in adult patients with injury to the upper extremities at the Emergency Department A cross-sectional study
Background: Pain is one of the most common symptoms in the Emergency Department (ED) and is the cause of more than half of the visits to the ED. Several attempts to improve pain management have been done by using, for example, standards/guidelines and education. To our knowledge no one has investigated if and how different actions over a longitudinal period affect the frequency of pain documentation in the ED. Therefore the aim of this study was to describe the frequency of documented pain assessments in the ED. Method: A cross-sectional study during 2006-2012 was conducted. The care of patients with wrist/arm fractures or soft tissue injuries on upper extremities was evaluated. Result: Despite various actions our result shows that mandatory pain assessment in the patient's computerized medical record was the only successful intervention to improve the frequencies of documentation of pain assessment during care in the ED. During the study period, no documentation of reassessment of pain was found despite the fact that all patients received pain medication. Conclusion: To succeed in increasing the frequency of documented pain assessment, mandatory pain rating is a successful action. However, the re-evaluation of documented pain assessment was nonexisting. (C) 2016 Elsevier Ltd. All rights reserved.Peer reviewe
On the Point-Splitting Method of the Commutator Anomaly of the Gauss Law Operators
We analyze the generalized point-splitting method and Jo's result for the
commutator anomaly. We find that certain classes of general regularization
kernels satisfying integral conditions provide a unique result, which, however
differs from Faddeev's cohomological result.Comment: 16 pages, RevTex, 1 figure + 1 table, uses psbox.te
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