47,724 research outputs found
Application of large eddy interaction model to channel flow
A procedure utilizing an expansion of proper orthogonal functions (or modes) to predict a fully developed flow in channel is derived. To examine numerical and conceptual difficulties, preliminary computations are performed with assigned mean velocity, and turbulence is expressed with only the first mode. The nonlinear interactions of the components of the first mode are treated specifically, with the influence of higher modes neglected; this treatment required adjustment of the skewness and effective Reynolds number to assure energy equilibrium of the first mode. Computational results show that the first mode possesses the structural character similar to that of the entire flow
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the C+Pb System at Near-Coulomb-Barrier Energies by using a Folding Potential
Simultaneous analyses are performed for elastic scattering and
fusion cross section data for the C+Pb system at
near-Coulomb-barrier energies by using the extended optical model approach in
which the polarization potential is decomposed into direct reaction (DR) and
fusion parts. Use is made of the double folding potential as a bare potential.
It is found that the experimental elastic scattering and fusion data are well
reproduced without introducing any normalization factor for the double folding
potential and also that both DR and fusion parts of the polarization potential
determined from the analyses satisfy separately the dispersion
relation. Furthermore, it is shown that the imaginary parts of both DR and
fusion potentials at the strong absorption radius change very rapidly, which
results in a typical threshold anomaly in the total imaginary potential as
observed with tightly bound projectiles such as -particle and O.Comment: 26 pages, 7 figures, submitted to Physical Review
Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 7Li+208Pb System at Near-Coulomb-Barrier Energies using the Folding Potential
Simultaneous analyses previously made for elastic scattering and
fusion cross section data for the Li+Pb system is extended to the
Li+Pb system at near-Coulomb-barrier energies based on the
extended optical model approach, in which the polarization potential is
decomposed into direct reaction (DR) and fusion parts. Use is made of the
double folding potential as a bare potential. It is found that the experimental
elastic scattering and fusion data are well reproduced without introducing any
normalization factor for the double folding potential and that both the DR and
fusion parts of the polarization potential determined from the
analyses satisfy separately the dispersion relation. Further, we find that the
real part of the fusion portion of the polarization potential is attractive
while that of the DR part is repulsive except at energies far below the Coulomb
barrier energy. A comparison is made of the present results with those obtained
from the Continuum Discretized Coupled Channel (CDCC) calculations and a
previous study based on the conventional optical model with a double folding
potential. We also compare the present results for the Li+Pb system
with the analysis previously made for the Li+Pb system.Comment: 7 figures, submitted to PR
Neutron Stars with Bose-Einstein Condensation of Antikaons as MIT Bags
We investigate the properties of an antikaon in medium, regarding itas a MIT
bag. We first construct the MIT bag model for a kaon with and
in order to describe the interaction of-quarks in hyperonic matter in the
framework of the modifiedquark-meson coupling model. The coupling constant
in the density-dependent bag constant is treated
as afree parameter to reproduce the optical potential of a kaon in asymmetric
matter and all other couplings are determined by usingSU(6) symmetry and the
quark counting rule. With various values ofthe kaon potential, we calculate the
effective mass of a kaon inmedium to compare it with that of a point-like kaon.
We thencalculate the population of octet baryons, leptons and and
theequation of state for neutron star matter. The results show thatkaon
condensation in hyperonic matter is sensitive to the -quarkinteraction and
also to the way of treating the kaon. The mass andthe radius of a neutron star
are obtained by solving theTolmann-Oppenheimer-Volkoff equation.Comment: 14 figure
The GEMS Approach to Stationary Motions in the Spherically Symmetric Spacetimes
We generalize the work of Deser and Levin on the unified description of
Hawking radiation and Unruh effect to general stationary motions in spherically
symmetric black holes. We have also matched the chemical potential term of the
thermal spectrum of the two sides for uncharged black holes.Comment: Latex file, 12 pages, no figure; v2: typos fixed; v3: minor
corrections, final version published in JHE
model with Hopf term and fractional spin statistics
We reconsider the model with the Hopf term by using the
Batalin-Fradkin-Tyutin (BFT) scheme, which is an improved version of the Dirac
quantization method. We also perform a semi-classical quantization of the
topological charge Q sector by exploiting the collective coordinates to
explicitly show the fractional spin statistics.Comment: 15 page
Interactions Among Positions in the Third and Fourth Membrane-Associated Domains at the Intersubunit Interface of the N-Methyl-D-Aspartate Receptor Forming Sites of Alcohol Action
The N-methyl-d-aspartate (NMDA) glutamate receptor is a major target of ethanol in the brain. Previous studies have identified positions in the third and fourth membrane-associated (M) domains of the NMDA receptor GluN1 and GluN2A subunits that influence alcohol sensitivity. The predicted structure of the NMDA receptor, based on that of the related GluA2 subunit, indicates a close apposition of the alcohol-sensitive positions in M3 and M4 between the two subunit types. We tested the hypothesis that these positions interact to regulate receptor kinetics and ethanol sensitivity by using dual substitution mutants. In single-substitution mutants, we found that a position in both subunits adjacent to one previously identified, GluN1(Gly-638) and GluN2A(Phe-636), can strongly regulate ethanol sensitivity. Significant interactions affecting ethanol inhibition and receptor deactivation were observed at four pairs of positions in GluN1/GluN2A: Gly-638/Met-823, Phe-639/Leu-824, Met-818/Phe-636, and Leu-819/Phe-637; the latter pair also interacted with respect to desensitization. Two interactions involved a position in M4 of both subunits, GluN1(Met-818) and GluN2A(Leu-824), that does not by itself alter ethanol sensitivity, whereas a previously identified ethanol-sensitive position, GluN2A(Ala-825), did not unequivocally interact with any other position tested. These results also indicate a shift by one position of the predicted alignment of the GluN1 M4 domain. These findings have allowed for the refinement of the NMDA receptor M domain structure, demonstrate that this region can influence apparent agonist affinity, and support the existence of four sites of alcohol action on the NMDA receptor, each consisting of five amino acids at the M3-M4 domain intersubunit interfaces
Flavor symmetry breaking effects on SU(3) Skyrmion
We study the massive SU(3) Skyrmion model to investigate the flavor symmetry
breaking (FSB) effects on the static properties of the strange baryons in the
framework of the rigid rotator quantization scheme combined with the improved
Dirac quantization one. Both the chiral symmetry breaking pion mass and FSB
kinetic terms are shown to improve the ratio of the strange-light to
light-light interaction strengths and that of the strange-strange to
light-light.Comment: 12 pages, latex, no figure
A Note on the Generalization of the GEMS Approach
This paper is a supplement of our earlier work JHEP 0410 (2004)
011[gr-qc/0409107].We map the vector potential of charged black holes into GEMS
and find that its effect on the thermal spectrum is the same as that on the
black hole side, i.e., it will induce a chemical potential in the thermal
spectrum which is the same as that in the charged black holes.We also argue
that the generalization of GEMS approach to non-stationary motions is not
possible.Comment: Latex file, 10 pages, no figure; v2: minor corrections; v3: revised
with title changed, one new section added and references adde
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