Does the Impact of Oportunidades Program Increases in Highly Competitive Regions?

Evidence on Oportunidades, a successful anti-poverty program in Mexico, has suggested that changes to the current grant structure may induce considerable improvements to its effectiveness. Moreover, there are proposals addressing the importance of regional, observable and unobservable characteristics, regarding its implementation. It is employed competitiveness level outcomes to investigate if this social policy has heterogeneous performance in different regions of intervention. For this purpose, a Difference-in-Difference model is applied to estimate short and mid-term impacts on enrolment rates. Results indicate that the general competitiveness effect is positive but not robust, given the considerable level of aggregation of the data used, whereas if it is distinguised Oportunidades treatment by selected competitiveness outcomes, states with highly efficient government institutions, middle competitive economic sectors and middle inclusive, educated and healthy individuals, present a larger program impact on enrolment rates. It is confirmed the significant improvements to program effectiveness and the impact of the competitiveness variables when it is considered only a sample of older children.Social policy effectiveness, competitiveness outcomes, school enrolment rates, regional effects, difference-in-difference (DID) model

Optimum matchings in weighted bipartite graphs

Given an integer weighted bipartite graph $\{G=(U\sqcup V, E), w:E\rightarrow \mathbb{Z}\}$ we consider the problems of finding all the edges that occur in some minimum weight matching of maximum cardinality and enumerating all the minimum weight perfect matchings. Moreover, we construct a subgraph $G_{cs}$ of $G$ which depends on an $\epsilon$-optimal solution of the dual linear program associated to the assignment problem on $\{G,w\}$ that allows us to reduced this problems to their unweighed variants on $G_{cs}$. For instance, when $G$ has a perfect matching and we have an $\epsilon$-optimal solution of the dual linear program associated to the assignment problem on $\{G,w\}$, we solve the problem of finding all the edges that occur in some minimum weight perfect matching in linear time on the number of edges. Therefore, starting from scratch we get an algorithm that solves this problem in time $O(\sqrt{n}m\log(nW))$, where $n=|U|\geq |V|$, $m=|E|$, and $W={\rm max}\{|w(e)|\, :\, e\in E\}$.Comment: 11 page

Superconducting Circuits for Quantum Simulation of Dynamical Gauge Fields

We describe a superconducting-circuit lattice design for the implementation and simulation of dynamical lattice gauge theories. We illustrate our proposal by analyzing a one-dimensional U(1) quantum-link model, where superconducting qubits play the role of matter fields on the lattice sites and the gauge fields are represented by two coupled microwave resonators on each link between neighboring sites. A detailed analysis of a minimal experimental protocol for probing the physics related to string breaking effects shows that despite the presence of decoherence in these systems, distinctive phenomena from condensed-matter and high-energy physics can be visualized with state-of-the-art technology in small superconducting-circuit arrays

Regular black holes in f(G)f(G) gravity

In this work, we study the possibility of generalizing solutions of regular black holes with an electric charge, constructed in general relativity, for the $f(G)$ theory, where $G$ is the Gauss-Bonnet invariant. This type of solution arises due to the coupling between gravitational theory and nonlinear electrodynamics. We construct the formalism in terms of a mass function and it results in different gravitational and electromagnetic theories for which mass function. The electric field of these solutions are always regular and the strong energy condition is violated in some region inside the event horizon. For some solutions, we get an analytical form for the $f(G)$ function. Imposing the limit of some constant going to zero in the $f(G)$ function we recovered the linear case, making the general relativity a particular case.Comment: 22 pages, 25 figures.Version published in EPJ

Ground-state properties of hard-core bosons confined on one-dimensional optical lattices

We study the ground-state properties of hard-core bosons trapped by arbitrary confining potentials on one-dimensional optical lattices. A recently developed exact approach based on the Jordan-Wigner transformation is used. We analyze the large distance behavior of the one-particle density matrix, the momentum distribution function, and the lowest natural orbitals. In addition, the low-density limit in the lattice is studied systematically, and the results obtained compared with the ones known for the hard-core boson gas without the lattice.Comment: RevTex file, 14 pages, 22 figures, published versio

Hadamard state in Schwarzschild-de Sitter spacetime

We construct a state in the Schwarzschild-de Sitter spacetime which is invariant under the action of its group of symmetries. Our state is not defined in the whole Kruskal extension of this spacetime, but rather in a subset of the maximally extended conformal diagram. The construction is based on a careful use of the bulk-to-boundary technique. We will show that our state is Hadamard and that it is not a KMS state, differently from the case of states constructed in spacetimes containing only one event horizon.Comment: More emphasis put on the result. 41 pages. Uses natbib and iopart. This version is going to be published in Classical and Quantum Gravity. PACS numbers: 04.62.+v,04.70.Dy,03.65.Fd. arXiv admin note: text overlap with arXiv:0907.1034 by other author