1,755 research outputs found
Clustering statistics in cosmology
The main tools in cosmology for comparing theoretical models with the
observations of the galaxy distribution are statistical. We will review the
applications of spatial statistics to the description of the large-scale
structure of the universe. Special topics discussed in this talk will be:
description of the galaxy samples, selection effects and biases, correlation
functions, Fourier analysis, nearest neighbor statistics, Minkowski functionals
and structure statistics. Special attention will be devoted to scaling laws and
the use of the lacunarity measures in the description of the cosmic texture.Comment: 15 pages, 7 figures, uses spie.cls (included). This paper will be
published in SPIE Proceedings Vol. 4847, 2002, "Astronomical Data Analysis
II," J.-L. Stark and F. Murtagh, eds., and is made available as an electronic
preprint with permission of SPI
Vortex-glass transition in superconducting Nb/Cu superlattices
Nb/Cu superconducting superlattices have been fabricated by dc magnetron
sputtering. This system shows a vortex glass transition with critical exponents
similar to high temperatures superconductors exponents. The transition
dymensionality is governed by the superconducting coupling regime. The vortex
glass transition shows a pure two dimensional behavior in decoupled
superlattices and a quasi-two dimensional behavior in the superlattice coupling
regime.Comment: 9 pages, 3 figure
Geometric approach to non-relativistic Quantum Dynamics of mixed states
In this paper we propose a geometrization of the non-relativistic quantum
mechanics for mixed states. Our geometric approach makes use of the Uhlmann's
principal fibre bundle to describe the space of mixed states and as a novelty
tool, to define a dynamic-dependent metric tensor on the principal manifold,
such that the projection of the geodesic flow to the base manifold gives the
temporal evolution predicted by the von Neumann equation. Using that approach
we can describe every conserved quantum observable as a Killing vector field,
and provide a geometric proof for the Poincare quantum recurrence in a physical
system with finite energy levels.Comment: 19 pages, 1 figure. Minor corrections. Accepted to Journal of
Mathematical Physic
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