31,560 research outputs found
Information theory of quantum systems with some hydrogenic applications
The information-theoretic representation of quantum systems, which
complements the familiar energy description of the density-functional and
wave-function-based theories, is here discussed. According to it, the internal
disorder of the quantum-mechanical non-relativistic systems can be quantified
by various single (Fisher information, Shannon entropy) and composite (e.g.
Cramer-Rao, LMC shape and Fisher-Shannon complexity) functionals of the
Schr\"odinger probability density. First, we examine these concepts and its
application to quantum systems with central potentials. Then, we calculate
these measures for hydrogenic systems, emphasizing their predictive power for
various physical phenomena. Finally, some recent open problems are pointed out.Comment: 9 pages, 3 figure
A Unifying Framework for the Problem of Adjudicating Conflicting Claims
In a recent paper, Thomson and Yeh [Operators for the adjudication of conflicting claims, Journal of Economic Theory 143 (2008) 177-198] introduced the concept of operators on the space of rules for the problem of adjudicating conflicting claims. They focussed on three operators in order to uncover the structure of such a space. In this paper, we generalize their analysis upon presenting and studying a general family of operators inspired by three apparently unrelated approaches to the problem of adjudicating conflicting claims. We study the structural properties of this family and show, in particular, that most of Thomson and Yeh’s results are specific cases of our study.rationing; operators; baselines; composition; claims
Dynamics of a Rigid Rod in a Glassy Medium
We present simulations of the motion of a single rigid rod in a disordered
static 2d-array of disk-like obstacles. The rotational, , and
center-of-mass translational, , diffusion constants are calculated
for a wide range of rod length and density of obstacles . It is found
that follows the behavior predicted by kinetic theory for a hard
disk with an effective radius . A dynamic crossover is observed in
for comparable to the typical distance between neighboring
obstacles . Using arguments from kinetic theory and reptation, we
rationalize the scaling laws, dynamic exponents, and prefactors observed for
. In analogy with the enhanced translational diffusion observed in
deeply supercooled liquids, the Stokes-Einstein-Debye relation is violated for
.Comment: 8 pages, 4 figures. Major changes. To be published in Europhysics
Letter
HEOS 1 helium observations in the solar wind
Results of alpha-particle observations performed by the European satellite HEOS 1, in the period from December 9, 1968, to April 13, 1969, and from September 6, 1969, to April 15, 1970, are presented. The average bulk velocities of protons V sub p and alpha-particles V sub alpha appear to be equal; however, due to an instrumental bias, the possibility of V sub alpha being lower than V sub p cannot be ruled out. Comparison with observations of Vela 3 and Explorer 34 satellites gives evidence of a dependence of helium abundance on the solar cycle. The problem of the stability of differences between the bulk velocities of protons and alpha-particles is investigated. The behavior of alpha-particles through interplanetary shock waves is illustrated in connection with magnetic field measurements
Cluster glasses of ultrasoft particles
We present molecular dynamics (MD) simulations results for dense fluids of
ultrasoft, fully-penetrable particles. These are a binary mixture and a
polydisperse system of particles interacting via the generalized exponential
model, which is known to yield cluster crystal phases for the corresponding
monodisperse systems. Because of the dispersity in the particle size, the
systems investigated in this work do not crystallize and form disordered
cluster phases. The clustering transition appears as a smooth crossover to a
regime in which particles are mostly located in clusters, isolated particles
being infrequent. The analysis of the internal cluster structure reveals
microsegregation of the big and small particles, with a strong
homo-coordination in the binary mixture. Upon further lowering the temperature
below the clustering transition, the motion of the clusters' centers-of-mass
slows down dramatically, giving way to a cluster glass transition. In the
cluster glass, the diffusivities remain finite and display an activated
temperature dependence, indicating that relaxation in the cluster glass occurs
via particle hopping in a nearly arrested matrix of clusters. Finally we
discuss the influence of the microscopic dynamics on the transport properties
by comparing the MD results with Monte Carlo simulations.Comment: 17 pages, 23 figure
A monopole solution from noncommutative multi-instantons
We extend the relation between instanton and monopole solutions of the
selfduality equations in SU(2) gauge theory to noncommutative space-times.
Using this approach and starting from a noncommutative multi-instanton solution
we construct a U(2) monopole configuration which lives in 3 dimensional
ordinary space. This configuration resembles the Wu-Yang monopole and satisfies
the selfduality (Bogomol'nyi) equations for a U(2) Yang-Mills-Higgs system.Comment: 19 pages; title and abstract changed, brane interpretation corrected.
Version to appear in JHE
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