164,627 research outputs found
Quantization of the universe as a black hole
It has been shown that black holes can be quantized by using Bohr's idea of
quantizing the motion of an electron inside the atom. We apply these ideas to
the universe as a whole. This approach reinforces the suggestion that it may be
a way to unify gravity with quantum theory.Comment: 7 pages. Accepted for publication in Astrophysics & Space Science in
25th Octuber 201
Lipschitz perturbations of expansive systems
We extend some known results from smooth dynamical systems to the category of
Lipschitz homeomorphisms of compact metric spaces. We consider dynamical
properties as robust expansiveness and structural stability allowing Lipschitz
perturbations with respect to a hyperbolic metric. We also study the
relationship between Lipschitz topologies and the topology on smooth
manifolds
Harder-Narasimhan filtration for rank 2 tensors and stable coverings
We construct a Harder-Narasimhan filtration for rank tensors, where there
does not exist any such notion a priori, as coming from a GIT notion of maximal
unstability. The filtration associated to the 1-parameter subgroup of Kempf
giving the maximal way to destabilize, in the GIT sense, a point in the
parameter space of the construction of the moduli space of rank tensors
over a smooth projective complex variety, does not depend on certain integer
used in the construction of the moduli space, for large values of the integer.
Hence, this filtration is unique and we define the Harder-Narasimhan filtration
for rank tensors as this unique filtration coming from GIT. Symmetric rank
tensors over smooth projective complex curves define curve coverings lying
on a ruled surface, hence we can translate the stability condition to define
stable coverings and characterize the Harder-Narasimhan filtration in terms of
intersection theory.Comment: 22 pages; Minor changes suggested by the referee; To appear on Proc.
Indian Acad. Sci. (Math. Sci.
Explaining the trasitions out of unemployement in Spain : the effect of unemployement insurance
In this article we study the factors that affect the transitions out of unemployment in Spain. We pay special attention to the impact of unemployment insurance benefits on the re-employment probability. We use a multinomiallogit model, and data from the EPA matched files from the second quarter of 1987 to the fourth quarter of 1995. Consistent with previous work, we find a negative effect of unemployment insurance receipt on the re-employment probability, and on withdrawal from the labor force. More importantly, we find a differential effect of benefit receipt when comparing time periods before and afier 1992. In april of that year the labor authority made eligibility requirements for unemployment insurance more restrictive, and curtailed benefit amounts
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