28,685 research outputs found
Exact Solution of an Irreversible One-Dimensional Model with Fully Biased Spin Exchanges
We introduce a model with conserved dynamics, where nearest neighbor pairs of
spins can exchange to assume the
configuration , with rate , through energy decreasing moves only. We report exact solution for
the case when one of the rates, or , is zero. The
irreversibility of such dynamics results in strong dependence on the initial
conditions. Domain wall arguments suggest that for more general models with
steady states the dynamical critical exponent for the anisotropic spin exchange
is different from the isotropic value.Comment: 16 pages, plain TeX fil
Exact Solutions of Low-Dimensional Reaction-Diffusion Systems
We briefly review some common diffusion-limited reactions with emphasis on
results for two-species reactions with anisotropic hopping. Our review also
covers single-species reactions. The scope is that of providing reference and
general discussion rather than details of methods and results. Recent exact
results for a two-species model with anisotropic hopping and with `sticky'
interaction of like particles, obtained by a novel method which allows exact
solution of certain single-species and two-species reactions, are discussed.Comment: 6 pages LaTeX file, to appear in the IJMP
Energy dependence of a vortex line length near a zigzag of pinning centers
A vortex line, shaped by a zigzag of pinning centers, is described here
through a three-dimensional unit cell containing two pinning centers positioned
symmetrically with respect to its center. The unit cell is a cube of side
, the pinning centers are insulating spheres of radius , taken
within the range to , being the coherence length. We
calculate the free energy density of these systems in the framework of the
Ginzburg-Landau theory.Comment: Submitted to Braz. Jour. Phys. (http://www.sbfisica.org.br/bjp) 11
pages, 6 figures, 1 table, LaTex 2
A Laplace transform approach to the quantum harmonic oscillator
The one-dimensional quantum harmonic oscillator problem is examined via the
Laplace transform method. The stationary states are determined by requiring
definite parity and good behaviour of the eigenfunction at the origin and at
infinity
Quantitative vs Qualitative public investment: The case of Portuguese Manufacturing between 1988 and 1992
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