82,276 research outputs found
On the Casimir effect for parallel plates in the spacetime with one extra compactified dimension
In this paper, the Casimir effect for parallel plates in the presence of one
compactified universal extra dimension is reexamined in detail. Having
regularized the expressions of Casimir force, we show that the nature of
Casimir force is repulsive if the distance between the plates is large enough,
which is disagree with the experimental phenomena.Comment: 7 pages, 3 figure
Time Quantified Monte Carlo Algorithm for Interacting Spin Array Micromagnetic Dynamics
In this paper, we reexamine the validity of using time quantified Monte Carlo
(TQMC) method [Phys. Rev. Lett. 84, 163 (2000); Phys. Rev. Lett. 96, 067208
(2006)] in simulating the stochastic dynamics of interacting magnetic
nanoparticles. The Fokker-Planck coefficients corresponding to both TQMC and
Langevin dynamical equation (Landau-Lifshitz-Gilbert, LLG) are derived and
compared in the presence of interparticle interactions. The time quantification
factor is obtained and justified. Numerical verification is shown by using TQMC
and Langevin methods in analyzing spin-wave dispersion in a linear array of
magnetic nanoparticles.Comment: Accepted for publication in Phys. Rev.
INCORPORATING SUBSISTENCE INTO A PROBIT ANALYSIS OF HOUSEHOLD NUTRITION LEVELS
Previous nutrient demand and consumption analyses show that several economic and sociodemographic variables are often associated with intakes. However, most of the literature does not account for differences among individuals within households. This study reviewed possible definitions of nutrient differences with respect to nutritional needs. Nutrient levels defined by the Thrifty Food Plan were used as subsistence levels for households in the 1977-78 Nationwide Food Consumption Survey. Probit analysis showed that the usual variables found related to nutrient intakes did not differentiate among subsistence groups. Household life cycle and working female heads influenced whether the household was under its requirement level.Food Consumption/Nutrition/Food Safety,
Maxwell Equation for the Coupled Spin-Charge Wave Propagation
We show that the dissipationless spin current in the ground state of the
Rashba model gives rise to a reactive coupling between the spin and charge
propagation, which is formally identical to the coupling between the electric
and the magnetic fields in the 2+1 dimensional Maxwell equation. This analogy
leads to a remarkable prediction that a density packet can spontaneously split
into two counter propagation packets, each carrying the opposite spins. In a
certain parameter regime, the coupled spin and charge wave propagates like a
transverse "photon". We propose both optical and purely electronic experiments
to detect this effect.Comment: 4 page
Solving the Master Equation for Extremely Long Time Scale Calculations
The dynamics of magnetic reversal process plays an important role in the
design of the magnetic recording devices in the long time scale limit. In
addition to long time scale, microscopic effects such as the entropic effect
become important in magnetic nano-scale systems. Many advanced simulation
methods have been developed, but few have the ability to simulate the long time
scale limit and to accurately model the microscopic effects of nano-scale
systems at the same time. We develop a new Monte Carlo method for calculating
the dynamics of magnetic reversal at arbitrary long time. For example, actual
calculations were performed up to 1e50 Monte Carlo steps. This method is based
on microscopic interactions of many constituents and the master equation for
magnetic probability distribution function is solved symbolically.Comment: accepted for publication in Computer Physics and Communication
Boundary effect on CDW: Friedel oscillations, STM image
We study the effect of open boundary condition on charge density waves (CDW).
The electron density oscillates rapidly close to the boundary, and additional
non-oscillating terms (~ln(r)) appear. The Friedel oscillations survive beyond
the CDW coherence length (v_F/Delta), but their amplitude gets heavily
suppressed. The scanning tunneling microscopy image (STM) of CDW shows clear
features of the boundary. The local tunneling conductance becomes asymmetric
with respect to the Fermi energy, and considerable amount of spectral weight is
transferred to the lower gap edge. Also it exhibits additional zeros reflecting
the influence of the boundary.Comment: 7 pages, 6 figure
Cross-section and polarization of neutrino-produced 's made simple
Practical formulae are derived for the cross-section and polarization of the
lepton produced in deep-inelastic neutrino-nucleon scattering in the
frame of the simple quark-parton model.Comment: 10 pages, no figure
Quantum Spin Hall Effect
The quantum Hall liquid is a novel state of matter with profound emergent
properties such as fractional charge and statistics. Existence of the quantum
Hall effect requires breaking of the time reversal symmetry caused by an
external magnetic field. In this work, we predict a quantized spin Hall effect
in the absence of any magnetic field, where the intrinsic spin Hall conductance
is quantized in units of . The degenerate quantum Landau
levels are created by the spin-orbit coupling in conventional semiconductors in
the presence of a strain gradient. This new state of matter has many profound
correlated properties described by a topological field theory
- …