22,136 research outputs found
Recommended from our members
SDT: A Database Schema Design and Translation Tool Reference Manual Draft 4.1
On the way from matter-dominated era to dark energy universe
We develop the general program of the unification of matter-dominated era
with acceleration epoch for scalar-tensor theory or dark fluid. The general
reconstruction of single scalar-tensor theory is fulfilled. The explicit form
of scalar potential for which the theory admits matter-dominated era,
transition to acceleration and (asymptotically deSitter) acceleration epoch
consistent with WMAP data is found. The interrelation of the epochs of
deceleration-acceleration transition and matter dominance-dark energy
transition for dark fluids with general EOS is investigated. We give several
examples of such models with explicit EOS (using redshift parametrization)
where matter-dark energy domination transition may precede the
deceleration-acceleration transition. As some by-product, the reconstruction
scheme is applied to scalar-tensor theory to define the scalar potentials which
may produce the dark matter effect. The obtained modification of Newton
potential may explain the rotation curves of galaxies.Comment: LaTeX 12 pages, 1 figure, extended version to appear in PR
The Consistent Result of Cosmological Constant From Quantum Cosmology and Inflation with Born-Infeld Scalar Field
The Quantum cosmology with Born-Infeld(B-I) type scalar field is considered.
In the extreme limits of small cosmological scale factor the wave function of
the universe can also be obtained by applying the methods developed by
Hartle-Hawking(H-H) and Vilenkin. H-H wave function predicts that most Probable
cosmological constant equals to (
equals to the maximum of the kinetic energy of scalar field). It is different
from the original results() in cosmological constant obtained by
Hartle-Hawking. The Vilenkin wave function predicts a nucleating unverse with
largest possible cosmological constant and it is larger than . The
conclusions have been nicely to reconcile with cosmic inflation. We investigate
the inflation model with B-I type scalar field, and find that depends on
the amplitude of tensor perturbation , with the form
The vacuum energy in inflation epoch depends on the
tensor-to-scalar ratio . The amplitude of the
tensor perturbation can, in principle, be large enough to be
discovered. However, it is only on the border of detectability in future
experiments. If it has been observed in future, this is very interesting to
determine the vacuum energy in inflation epoch.Comment: 12 pages, one figure, references added, accepted by European Physical
Journal
Cosmology in Nonlinear Born-Infeld Scalar Field Theory With Negative Potentials
The cosmological evolution in Nonlinear Born-Infeld(hereafter NLBI) scalar
field theory with negative potentials was investigated. The cosmological
solutions in some important evolutive epoches were obtained. The different
evolutional behaviors between NLBI and linear(canonical) scalar field theory
have been presented. A notable characteristic is that NLBI scalar field behaves
as ordinary matter nearly the singularity while the linear scalar field behaves
as "stiff" matter. We find that in order to accommodate current observational
accelerating expanding universe the value of potential parameters and
must have an {\it upper bound}. We compare different cosmological
evolutions for different potential parameters .Comment: 18 pages, 18 figures, some references added, revised version for
Int.J.Mod.Phys.A, appeared in Int.J.Mod.Phys.
Evidence for multiple impurity bands in sodium-doped silicon MOSFETs
We report measurements of the temperature-dependent conductivity in a silicon
metal-oxide-semiconductor field-effect transistor that contains sodium
impurities in the oxide layer. We explain the variation of conductivity in
terms of Coulomb interactions that are partially screened by the proximity of
the metal gate. The study of the conductivity exponential prefactor and the
localization length as a function of gate voltage have allowed us to determine
the electronic density of states and has provided arguments for the presence of
two distinct bands and a soft gap at low temperature.Comment: 4 pages; 5 figures; Published in PRB Rapid-Communication
EventCap: Monocular 3D Capture of High-Speed Human Motions using an Event Camera
The high frame rate is a critical requirement for capturing fast human motions. In this setting, existing markerless image-based methods are constrained by the lighting requirement, the high data bandwidth and the consequent high computation overhead. In this paper, we propose EventCap --- the first approach for 3D capturing of high-speed human motions using a single event camera. Our method combines model-based optimization and CNN-based human pose detection to capture high-frequency motion details and to reduce the drifting in the tracking. As a result, we can capture fast motions at millisecond resolution with significantly higher data efficiency than using high frame rate videos. Experiments on our new event-based fast human motion dataset demonstrate the effectiveness and accuracy of our method, as well as its robustness to challenging lighting conditions
Effects of Contrarians in the Minority Game
We study the effects of the presence of contrarians in an agent-based model
of competing populations. Contrarians are common in societies. These
contrarians are agents who deliberately prefer to hold an opinion that is
contrary to the prevailing idea of the commons or normal agents. Contrarians
are introduced within the context of the Minority Game (MG), which is a binary
model for an evolving and adaptive population of agents competing for a limited
resource. Results of numerical simulations reveal that the average success rate
among the agents depends non-monotonically on the fraction of
contrarians. For small , the contrarians systematically outperform the
normal agents by avoiding the crowd effect and enhance the overall success
rate. For high , the anti-persistent nature of the MG is disturbed and
the few normal agents outperform the contrarians. Qualitative discussion and
analytic results for the small and high regimes are also
presented, and the crossover behavior between the two regimes is discussed.Comment: revtex, 11 pages, 4 figure
- …