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 $C^1$ topology on smooth manifolds

Harder-Narasimhan filtration for rank 2 tensors and stable coverings

We construct a Harder-Narasimhan filtration for rank $2$ 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 $2$ 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 $2$ tensors as this unique filtration coming from GIT. Symmetric rank $2$ 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