4,726 research outputs found
The twilight zone in the parametric evolution of eigenstates: beyond perturbation theory and semiclassics
Considering a quantized chaotic system, we analyze the evolution of its
eigenstates as a result of varying a control parameter. As the induced
perturbation becomes larger, there is a crossover from a perturbative to a
non-perturbative regime, which is reflected in the structural changes of the
local density of states. For the first time the {\em full} scenario is explored
for a physical system: an Aharonov-Bohm cylindrical billiard. As we vary the
magnetic flux, we discover an intermediate twilight regime where perturbative
and semiclassical features co-exist. This is in contrast with the {\em simple}
crossover from a Lorentzian to a semicircle line-shape which is found in
random-matrix models.Comment: 4 pages, 4 figures, improved versio
Contractions of low-dimensional nilpotent Jordan algebras
In this paper we classify the laws of three-dimensional and four-dimensional
nilpotent Jordan algebras over the field of complex numbers. We describe the
irreducible components of their algebraic varieties and extend contractions and
deformations among them. In particular, we prove that J2 and J3 are irreducible
and that J4 is the union of the Zariski closures of two rigid Jordan algebras.Comment: 12 pages, 3 figure
Aciertos y desencuentros en la defensa de los derechos humanos en la administración de Vicente Fox
El autor diserta con precisión jurÃdica sobre la situación de los derechos en todo el mundo, y en especÃfico opina sobre la actuación de México en los diversos organismos internacionales.ITESO, A.C
Las reformas constitucionales en derechos humanos de Vicente Fox
Estudio sobre las reformas en derechos humanos del régimen del presidente Vicente Fox. El artÃculo recoge diferentes inquietudes: las polÃticas económicas de la globalización, el descrédito de los polÃticos y el ausentismo de una sociedad públicamente pasiva. El autor considera que recuperar la verdadera democracia desde los valores humanos intocables, es el punto mÃnimo para recuperar la confianza y el entusiasmo en una sociedad desalentada y desencantada por los resultados de la alternativa polÃtica que está viviendo.ITESO, A.C
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