1,822,229 research outputs found
Induced Scattering and Two-Photon Absorption of Alfven Waves with Arbitrary Propagation Angles
The equation for temporary evolution of spectral energy of collisionless
Alfven waves is derived in framework of weak turbulence theory. The main
nonlinear processes for such conditions are induced scattering and two quantum
absorption of Alfven waves by thermal ions. The equation for velocity
distribution of thermal particles is derived that describes diffusion in
momentum space due to this nonlinear processes. Comparison is done with the
results of another authors. Results obtained are qualitatively differ from the
ones obtained for the case of Alfven waves propagation along mean magnetic
field.Comment: 8 page
Scaling Functions and Superscaling in Medium and Heavy Nuclei
The scaling function for medium and heavy nuclei with
for which the proton and neutron densities are not similar is constructed
within the coherent density fluctuation model (CDFM) as a sum of the proton and
neutron scaling functions. The latter are calculated in the cases of Ni,
Kr, Sn, and Au nuclei on the basis of the corresponding
proton and neutron density distributions which are obtained in deformed
self-consistent mean-field Skyrme HF+BCS method. The results are in a
reasonable agreement with the empirical data from the inclusive electron
scattering from nuclei showing superscaling for negative values of ,
including those smaller than -1. This is an improvement over the relativistic
Fermi gas (RFG) model predictions where becomes abruptly zero for
. It is also an improvement over the CDFM calculations made in
the past for nuclei with assuming that the neutron density is equal
to the proton one and using only the phenomenological charge density.Comment: 4 pages, 1 figure, ReVTeX, accepted for publication in Phys. Rev.
Weak ferromagnetism and spiral spin structures in honeycomb Hubbard planes
Within the Hartree Fock- RPA analysis, we derive the spin wave spectrum for
the weak ferromagnetic phase of the Hubbard model on the honeycomb lattice.
Assuming a uniform magnetization, the polar (optical) and acoustic branches of
the spin wave excitations are determined. The bipartite lattice geometry
produces a q-dependent phase difference between the spin wave amplitudes on the
two sub-lattices. We also find an instability of the uniform weakly magnetized
configuration to a weak antiferromagnetic spiraling spin structure, in the
lattice plane, with wave vector Q along the Gamma-K direction, for electron
densities n>0.6. We discuss the effect of diagonal disorder on both the
creation of electron bound states, enhancement of the density of states, and
the possible relevance of these effects to disorder induced ferromagnetism, as
observed in proton irradiated graphite.Comment: 13 pages, 7 figure
Ergodicity and mixing bounds for the Fisher-Snedecor diffusion
We consider the Fisher-Snedecor diffusion; that is, the Kolmogorov-Pearson
diffusion with the Fisher-Snedecor invariant distribution. In the nonstationary
setting, we give explicit quantitative rates for the convergence rate of
respective finite-dimensional distributions to that of the stationary
Fisher-Snedecor diffusion, and for the -mixing coefficient of this
diffusion. As an application, we prove the law of large numbers and the central
limit theorem for additive functionals of the Fisher-Snedecor diffusion and
construct -consistent and asymptotically normal estimators for the
parameters of this diffusion given its nonstationary observation.Comment: Published in at http://dx.doi.org/10.3150/12-BEJ453 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
In Vitro Fertility of Post-thawed Epididymal Ram Spermatozoa After Storage at 5 °C Before Cryopreservation
This study addressed the effects of storage duration of epididymides at 5 °C before sperm collection and their fertility after cryopreservation in vitro. Spermatozoa from one of the testes pairs were immediately collected, evaluated and frozen (control group). The remaining epididymides were cooled to 5 °C and stored for 24, 48, 72, and 96 h (experimental groups), after which spermatozoa were collected and frozen as in the control group. Before and after thawing, sperm motility, sperm viability and plasma membrane integrity were assessed. The fertilizing ability of frozen-thawed spermatozoa of each group was evaluated by in vitro fertilization of matured sheep oocytes. Sperm quality (sperm motility, viability, and plasma membrane integrity) at collection and after cryopreservation decreased as the duration of the epididymal storage interval increase (P < 0.05). The motility decreased steadily along the studied time periods. Although, the fertilizing ability of post-thawed epididymal spermatozoa gradually decreased as the storage period was prolonged, the spermatozoa collected from the cauda epididymides stored at 5 °C for up to 96 h were able to fertilize 16%-65% of oocytes in vitro. Results of the present study showed that ram epididymal spermatozoa survive in storage at 5 °C for up to 96 h. These spermatozoa maintain their fertilizing ability and may be suitable for use in IVF and other assisted reproductive procedures
Quantum and string shape fluctuations in the dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings
The magnetic monopole condensate is calculated in the dual Monopole
Nambu-Jona-Lasinio model with dual Dirac strings suggested in Refs.[1,2] as a
functional of the dual Dirac string shape. The calculation is carried out in
the tree approximation in the scalar monopole-antimonopole collective
excitation field. The integration over quantum fluctuations of the dual-vector
monopole-antimonopole collective excitation field around the Abrikosov flux
line and string shape fluctuations are performed explicitly. We claim that
there are important contributions of quantum and string shape fluctuations to
the magnetic monopole condensate.Comment: 19 pages, Latex, 2 figure
Confinement potential in dual Monopole Nambu-Jona-Lasinio model with dual Dirac strings
Interquark confinement potential is calculated in the dual Monopole
Nambu-Jona-Lasinio model with dual Dirac strings as a functional of a dual
Dirac string length. The calculation is carried out by the explicit integration
over quantum fluctuations of a dual-vector field (monopole-antimonopole
collective excitation) around the Abrikosov flux line and string shape
fluctuations. The contribution of the scalar field (monopole-antimonopole
collective excitation) exchange is taken into account in the tree approximation
due to the London limit regime.Comment: 10 pages, Latex, no figure
Image processing applications using a novel parallel computing machine based on reconfigurable logic
Zelig is a 32 physical node fine-grained computer employing field-programmable gate arrays. Its application to the high speed implementation of various image pre-processing operations (in particular binary morphology) is described together with typical speed-up result
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