38,327 research outputs found
Spherically symmetric trapping horizons, the Misner-Sharp mass and black hole evaporation
Understood in terms of pure states evolving into mixed states, the
possibility of information loss in black holes is closely related to the global
causal structure of spacetime, as is the existence of event horizons. However,
black holes need not be defined by event horizons, and in fact we argue that in
order to have a fully unitary evolution for black holes, they should be defined
in terms of something else, such as a trapping horizon. The Misner-Sharp mass
in spherical symmetry shows very simply how trapping horizons can give rise to
black hole thermodynamics, Hawking radiation and singularities. We show how the
Misner-Sharp mass can also be used to give insights into the process of
collapse and evaporation of locally defined black holes.Comment: 9 pages, 10 figure
Hydrogen adsorption on Pd(133) surface
In this study used is an approach based on measurements of the total energy
distribution (TED) of field emitted electrons in order to examine the
properties of Pd (133) from the aspect of both hydrogen adsorption and surface
hydrides formation. The most favourable sites offered to a hydrogen atom to be
adsorbed have been indicated and an attempt to describe the peaks of the
enhancement factor R spectrum to the specific adsorption sites has also been
made.Comment: to be submitted to the Centr. Eur. J. Phy
Hemodynamic evaluation using four-dimensional flow magnetic resonance imaging for a patient with multichanneled aortic dissection
The hemodynamic function of multichanneled aortic dissection (MCAD) requires close monitoring and effective management to avoid potentially catastrophic sequelae. This report describes a 47-year-old man who underwent endovascular repair based on findings from four-dimensional (4D) flow magnetic resonance imaging of an MCAD. The acquired 4D flow data revealed complex, bidirectional flow patterns in the false lumens and accelerated blood flow in the compressed true lumen. The collapsed abdominal true lumen expanded unsatisfactorily after primary tear repair, which required further remodeling with bare stents. This case study demonstrates that hemodynamic analysis using 4D flow magnetic resonance imaging can help understand the complex pathologic changes of MCAD
Rabi oscillations in a quantum dot-cavity system coupled to a non-zero temperature phonon bath
We study a quantum dot strongly coupled to a single high-finesse optical
microcavity mode. We use a rotating wave approximation method, commonly used in
ion-laser interactions, tegether with the Lamb-Dicke approximation to obtain an
analytic solution of this problem. The decay of Rabi oscillations because of
the electron-phonon coupling are studied at arbitrary temperature and
analytical expressions for the collapse and revival times are presented.
Analyses without the rotating wave approximation are presented by means of
investigating the energy spectrum.Comment: 7 pages, 5 figures; Revised versio
Analytical and experimental studies of surface ionization final report, 24 jan. - 30 sep. 1964
Rhodium, rhenium, and tungsten as cesium-ionizer materials in surface ionization engine
Geometrical and electronic structures of the (5, 3) single-walled gold nanotube from first-principles calculations
The geometrical and electronic structures of the 4 {\AA} diameter perfect and
deformed (5, 3) single-walled gold nanotube (SWGT) have been studied based upon
the density-functional theory in the local-density approximation (LDA). The
calculated relaxed geometries show clearly significant deviations from those of
the ideally rolled triangular gold sheet. It is found that the different
strains have different effects on the electronic structures and density of
states of the SWGTs. And the small shear strain can reduce the binding energy
per gold atom of the deformed SWGT, which is consistent with the experimentally
observed result. Finally, we found the finite SWGT can show the
metal-semiconductor transition.Comment: 11 pages, 4 figure
The structure of parafermion vertex operator algebras
It is proved that the parafermion vertex operator algebra associated to the
irreducible highest weight module for the affine Kac-Moody algebra A_1^{(1)} of
level k coincides with a certain W-algebra. In particular, a set of generators
for the parafermion vertex operator algebra is determined.Comment: 12 page
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