8,698 research outputs found
Refined Simulations of the Reaction Front for Diffusion-Limited Two-Species Annihilation in One Dimension
Extensive simulations are performed of the diffusion-limited reaction
AB in one dimension, with initially separated reagents. The reaction
rate profile, and the probability distributions of the separation and midpoint
of the nearest-neighbour pair of A and B particles, are all shown to exhibit
dynamic scaling, independently of the presence of fluctuations in the initial
state and of an exclusion principle in the model. The data is consistent with
all lengthscales behaving as as . Evidence of
multiscaling, found by other authors, is discussed in the light of these
findings.Comment: Resubmitted as TeX rather than Postscript file. RevTeX version 3.0,
10 pages with 16 Encapsulated Postscript figures (need epsf). University of
Geneva preprint UGVA/DPT 1994/10-85
Are Currency Crises Low-State Equilibria? An Empirical, Three-Interest-Rate Model
Suppose that the dynamics of the macroeconomy were given by (partly) random fluctuations between two equilibria: "good" and "bad." One would interpret currency crises (or recessions) as a shift from the good equilibrium to the bad. In this paper, the authors specify a dynamic investment-savings-aggregate-supply (IS-AS) model, determine its closed-form solution, and examine numerically its comparative statics. The authors estimate the model via maximum likelihood, using data for Argentina, Canada, and Turkey. Since the data show no support for the multiple-equilibrium explanation of fluctuations, the authors cast doubt on the third-generation models of currency crisis.Uncertainty and monetary policy
The Reaction-Diffusion Front for in One Dimension
We study theoretically and numerically the steady state diffusion controlled
reaction , where currents of and particles
are applied at opposite boundaries. For a reaction rate , and equal
diffusion constants , we find that when the
reaction front is well described by mean field theory. However, for , the front acquires a Gaussian profile - a result of
noise induced wandering of the reaction front center. We make a theoretical
prediction for this profile which is in good agreement with simulation.
Finally, we investigate the intrinsic (non-wandering) front width and find
results consistent with scaling and field theoretic predictions.Comment: 11 pages, revtex, 4 separate PostScript figure
Critical Temperature of a Trapped Bose Gas: Mean-Field Theory and Fluctuations
We investigate the possibilities of distinguishing the mean-field and
fluctuation effects on the critical temperature of a trapped Bose gas with
repulsive interatomic interactions. Since in a direct measurement of the
critical temperature as a function of the number of trapped atoms these effects
are small compared to the ideal gas results, we propose to observe
Bose-Einstein condensation by adiabatically ramping down the trapping
frequency. Moreover, analyzing this adiabatic cooling scheme, we show that
fluctuation effects can lead to the formation of a Bose condensate at
frequencies which are much larger than those predicted by the mean-field
theory.Comment: 4 pages of ReVTeX and 3 figures. Submitted to Physical Review
Decay Process for Three - Species Reaction - Diffusion System
We propose the deterministic rate equation of three-species in the reaction -
diffusion system. For this case, our purpose is to carry out the decay process
in our three-species reaction-diffusion model of the form . The
particle density and the global reaction rate are also shown analytically and
numerically on a two-dimensional square lattice with the periodic boundary
conditions. Especially, the crossover of the global reaction rate is discussed
in both early-time and long-time regimes.Comment: 6 pages, 3 figures, Late
Black hole quasinormal modes using the asymptotic iteration method
In this article we show that the asymptotic iteration method (AIM) allows one
to numerically find the quasinormal modes of Schwarzschild and Schwarzschild de
Sitter (SdS) black holes. An added benefit of the method is that it can also be
used to calculate the Schwarzschild anti-de Sitter (SAdS) quasinormal modes for
the case of spin zero perturbations. We also discuss an improved version of the
AIM, more suitable for numerical implementation.Comment: 10 pages, LaTeX; references added; substantially expanded versio
Graviton emission from simply rotating Kerr-de Sitter black holes: Transverse traceless tensor graviton modes
In this article we present results for tensor graviton modes (in seven
dimensions and greater, ) for greybody factors of Kerr-dS black holes
and for Hawking radiation from simply rotating (n+4)-dimensional Kerr black
holes. Although there is some subtlety with defining the Hawking temperature of
a Kerr-dS black hole, we present some preliminary results for emissions
assuming the standard Hawking normalization and a Bousso-Hawking-like
normalization.Comment: 12 pages, 18 figure
Angular Eigenvalues of Higher-Dimensional Kerr-(A)dS Black Holes with Two Rotations
In this paper, following the work of Chen, L\"u and Pope, we present the
general metric for Kerr-(A)dS black holes with two rotations. The corresponding
Klein-Gordon equation is separated explicitly, from which we develop
perturbative expansions for the angular eigenvalues in powers of the rotation
parameters with .Comment: 10 pages, no figures. To appear in the proceedings of 2011 Shanghai
Asia-Pacific School and Workshop on Gravitatio
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