13,233 research outputs found
Time-Dependent Dynamics of the Bose-Fermi Mixed Condensed System
We study the monopole oscillation in the bose-fermi mixed condensed system by
performing the time-dependent Gross-Pitaevsky (GP) and Vlasov equations. We
find that the big damping exists for the fermion oscillation in the mixed
system even at zero temperatureComment: 5pages, 2 figure
Nonequilibrium Green's Function Approach to Phonon Transport in Defective Carbon Nanotubes
We have developed a new theoretical formalism for phonon transport in
nanostructures using the nonequilibrium phonon Green's function technique and
have applied it to thermal conduction in defective carbon nanotubes. The
universal quantization of low-temperature thermal conductance in carbon
nanotubes can be observed even in the presence of local structural defects such
as vacancies and Stone-Wales defects, since the long wavelength acoustic
phonons are not scattered by local defects. At room temperature, however,
thermal conductance is critically affected by defect scattering since incident
phonons are scattered by localized phonons around the defects. We find a
remarkable change from quantum to classical features for the thermal transport
through defective CNTs with increasing temperature.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev. Let
Superconductivity without Local Inversion Symmetry; Multi-layer Systems
While multi-layer systems can possess global inversion centers, they can have
regions with locally broken inversion symmetry. This can modify the
superconducting properties of such a system. Here we analyze two dimensional
multi-layer systems yielding spatially modulated antisymmetric spin-orbit
coupling (ASOC) and discuss superconductivity with mixed parity order
parameters. In particular, the influence of ASOC on the spin susceptibility is
investigated at zero temperature. For weak inter-layer coupling we find an
enhanced spin susceptibility induced by ASOC, which hints the potential
importance of this aspect for superconducting phase in specially structured
superlattices.Comment: 4 pages, 2 figures, proceedings of the 26th International Conference
on Low Temperature Physics (LT26
Topological Invariants for Polyacetylene, Kagome and Pyrochlore lattices
Adiabatic invariants by quantized Berry phases are defined for gapped
electronic systems in -dimensions (). This series includes
Polyacetylene, Kagome and Pyrochlore lattice respectively for and 3.
The invariants are quantum -multimer order parameters to characterize the
topological phase transitions by the multimerization. This fractional
quantization is protected by the global equivalence. As for the chiral
symmetric case, a topological form of the -invariant is explicitly given
as well.Comment: 4 pgages, 4 figure
Isoscalar Giant Quadrupole Resonance State in the Relativistic Approach with the Momentum-Dependent Self-Energies
We study the excited energy of the isoscalar giant quadrupole resonance with
the scaling method in the relativistic many-body framework. In this calculation
we introduce the momentum-dependent parts of the Dirac self-energies arising
from the one-pion exchange on the assumption of the pseudo-vector coupling with
nucleon field. It is shown that this momentum-dependence enhances the Landau
mass significantly and thus suppresses the quadrupole resonance energy even
giving the small Dirac effective mass which causes a problem in the
momentum-independent mean-field theory.Comment: 12pages, 2 Postscript figure
An online handwritten music symbol recognition system
The original publication is available at www.springerlink.comArticleINTERNATIONAL JOURNAL ON DOCUMENT ANALYSIS AND RECOGNITION. 9(1): 49-58 (2007)journal articl
Noise-induced behaviors in neural mean field dynamics
The collective behavior of cortical neurons is strongly affected by the
presence of noise at the level of individual cells. In order to study these
phenomena in large-scale assemblies of neurons, we consider networks of
firing-rate neurons with linear intrinsic dynamics and nonlinear coupling,
belonging to a few types of cell populations and receiving noisy currents.
Asymptotic equations as the number of neurons tends to infinity (mean field
equations) are rigorously derived based on a probabilistic approach. These
equations are implicit on the probability distribution of the solutions which
generally makes their direct analysis difficult. However, in our case, the
solutions are Gaussian, and their moments satisfy a closed system of nonlinear
ordinary differential equations (ODEs), which are much easier to study than the
original stochastic network equations, and the statistics of the empirical
process uniformly converge towards the solutions of these ODEs. Based on this
description, we analytically and numerically study the influence of noise on
the collective behaviors, and compare these asymptotic regimes to simulations
of the network. We observe that the mean field equations provide an accurate
description of the solutions of the network equations for network sizes as
small as a few hundreds of neurons. In particular, we observe that the level of
noise in the system qualitatively modifies its collective behavior, producing
for instance synchronized oscillations of the whole network, desynchronization
of oscillating regimes, and stabilization or destabilization of stationary
solutions. These results shed a new light on the role of noise in shaping
collective dynamics of neurons, and gives us clues for understanding similar
phenomena observed in biological networks
Milk protein-derived peptide inhibitors of angiotensin-I-converting enzyme
peer-reviewedNumerous casein and whey protein-derived angiotensin-I-converting enzyme (ACE) inhibitory
peptides/hydrolysates have been identified. Clinical trials in hypertensive animals and humans
show that these peptides/hydrolysates can bring about a significant reduction in hypertension.
These peptides/hydrolysates may be classified as functional food ingredients and nutraceuticals
due to their ability to provide health benefits i.e. as functional food ingredients in reducing the
risk of developing a disease and as nutraceuticals in the prevention/treatment of disease
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