El Salvador: A Central American Tiger?

El Salvador is becoming an economic success story in Central America. Since the end of the civil conflict in 1992, which left the country in ruins, El Salvador has transformed its economy by implementing a far-reaching liberalization process undertaken by democratic governments, which has included the privatization of state enterprises, deregulation, trade and financial liberalization, privatization of the pension system, and the adoption of the U.S. dollar as its official currency. According to the Fraser Institute's Economic Freedom of the World Report, El Salvador ranks among the top 25 freest economies in the world. The results of the market reforms are notable: between 1991 and 2007, the percentage of households below the poverty line fell from 60 percent to 34.6 percent. However, official figures point to mediocre average annual per capita growth during the period 1992 -- 2007 -- only 1.9 percent -- which is very similar to Latin America's average of 1.6 percent in the same period. But official figures grossly underestimate the performance of the economy because of flawed measurement. In fact, the economy is probably more than 30 percent larger than indicated by the official data. Accordingly, the average per capita growth rate since 1992 has been approximately 5.2 percent per year. El Salvador still has much to do on its policy agenda. In particular, high crime rates constitute a major hindrance to further growth. This lack of security represents the greatest threat to sustained growth and liberal policies. Nonetheless, the country is showing the rest of the region how economic freedom can pave the way for development and how globalization offers great opportunities for developing countries that are willing to implement a coherent set of mutually supportive market reforms

Soft interactions in jet quenching

We study the collisional aspects of jet quenching in a high energy nuclear collision, especially in the final state pion gas. The jet has a large energy, and acquires momentum transverse to its axis more effectively by multiple soft collisions than by few hard scatterings (as known from analogous systems such as J/\psi production at Hera). Such regime of large E and small momentum transfer corresponds to Regge kinematics and is characteristically dominated by the pomeron. From this insight we estimate the jet quenching parameter in the hadron medium (largely a pion gas) at the end of the collision, which is naturally small and increases with temperature in line with the gas density. The physics in the quark-gluon plasma/liquid phase is less obvious, and here we revisit a couple of simple estimates that suggest indeed that the pomeron-mediated interactions are very relevant and should be included in analysis of the jet quenching parameter. Finally, the ocasional hard collisions produce features characteristic of a L\`evy flight in the q_perp^2 plane perpendicular to the jet axis. We suggest one- and two-particle q_perp correlations as interesting experimental probes.Comment: 14 pages, 16 figure

Hado de una Quimera

En lo alto del emblemático monumento de la Catedral de Notre-Dame en París, un hombre se enfrenta a los pensamientos que lo asaltan de manera angustiante. Motivado por una novela de Victor Hugo, busca "señales" en el interior de la iglesia, en un mundo que parece mudo. Mas olvida, que dicha inscripción no existe más. Es entonces que una pareja autraliana, cuya compañía le resulta inconcientemente incómoda, puesto que en ella se concentra una historia de amor, le señala hacia dónde debe buscar. Una Quimera parlante.¿Qué tienen que decir esos objetos sin voz? ¿Las quimeras de París, hablan? ¿Cómo conciliar el vértigo de la Caída con el placer de existir? ¿Cómo no confundir tragedia con necedad? ¿Hasta qué punto el amor nos devuelve al mundo real?  

The energy crossroads : Strategies for sustainable energy development

Energy is the blood that moves today?s society and is one of the factors that has decisively contributed to improving humanity?s quality of life. The energy needs of the world?s population are expected to double by 2050 and so, considering that available fossil fuels are becoming exhausted, as well as their negative environmental impact, new strategies are needed for sustainable development. This paper addresses the potential challenges and opportunities in the development of global energy systems, emphasising how deeply interconnected the energy and climate debates are

Distribution Free Goodness-of-Fit Tests for Linear Processes

This article proposes a class of goodness-of-fit tests for the autocorrelation function of a time series process, including those exhibiting long-range dependence. Test statistics for composite hypotheses are functionals of a (approximated) martingale transformation of the Bartlett's Tp-process with estimated parameters, which converges in distribution to the standard Brownian Motion under the null hypothesis. We discuss tests of different nature such as omnibus, directional and Portmanteau-type tests. A Monte Carlo study illustrates the performance of the different tests in practice.Nonparametric model checking, spectral distribution, linear processes, martingale decomposition, local alternatives, omnibus, smooth and directional tests, long-range alternatives

Non-comoving baryons and cold dark matter in cosmic voids

We examine the fully relativistic evolution of cosmic voids constituted by baryons and cold dark matter (CDM), represented by two non-comoving dust sources in a $\Lambda$CDM background. For this purpose, we consider numerical solutions of Einstein's field equations in a fluid-flow representation adapted to spherical symmetry and multiple components. We present a simple example that explores the frame-dependence of the local expansion and the Hubble flow for this mixture of two dusts, revealing that the relative velocity between the sources yields a significantly different evolution in comparison with that of the two sources in a common 4-velocity (which reduces to a Lemaitre-Tolman-Bondi model). In particular, significant modifications arise for the density contrast depth and void size, as well as in the amplitude of the surrounding over-densities. We show that an adequate model of a frame-dependent evolution that incorporates initial conditions from peculiar velocities and large-scale density contrast observations may contribute to understand the discrepancy between the local value of $H_0$ and that inferred from the CMB.Comment: Discussion of the evolution of baryon-CDM relative velocity added. Other minor but important corrections were incorporated. Version accepted for publication in EPJ

Transport Infrastructure, Spatial General Equilibrium and Welfare

Large-scale investments in transport infrastructure have been traditionally evaluated assuming the equivalence between direct and indirect economic effects (Jara-Diaz,1986), which is only correct under -generally non-guaranteed- perfect competition assumptions. Despite this common practice there is still no consensus amongst economists as to how the benefits and costs of large infrastructure projects should be determined. The discussions regarding the desirability, for instance, of the Betuwe railway line, the fifth runway at Schiphol Airport, the North-South underground railway in Amsterdam etc. are illustrative of this. The focus has been, in particular, on the magnitude of ‘indirect’ and ‘strategic’ effects, that is effects on parties other than the direct users of the infrastructure (indirect effects) and those factors that have a favorable effect on the long-term development of the (regional) economy, such as effects relating to firm location and demographics (strategic effects). Focusing on general equilibrium, increasing returns and imperfect competition modeling approach this paper aims to throw light on this subject matter by examining how the social benefits in terms of efficiency resulting from improvements to the infrastructure can be determined in an imperfect regional economy.

Primordial Black Holes in non-linear perturbation theory

This thesis begins with a study of the origin of cosmological fluctuations with special attention to those cases in which the non-Gaussian correlation functions are large. The analysis shows that perturbations from an almost massless auxiliary field generically produce large values of the non-linear parameter f_NL. The effects of including non-Gaussian correlation functions in the statistics of cosmological structure are explored by constructing a non-Gaussian probability distribution function (PDF). Such PDF is derived for the comoving curvature perturbation from first principles in the context of quantum field theory, with n-point correlation functions as the only input. The non-Gaussian PDF is then used to explore two important problems in the physics of primordial black holes (PBHs): First, to compute non-Gaussian corrections to the number of PBHs generated from the primordial curvature fluctuations. The second application concerns new cosmological observables. The formation of PBHs is known to depend on two main physical characteristics: the strength of the gravitational field produced by the initial curvature inhomogeneity and the pressure gradient at the edge of the curvature configuration. We account for the probability of finding these configurations by using two parameters: The amplitude of the inhomogeneity and its second radial derivative, evaluated at the centre of the configuration. The implications of the derived probability for the fraction of mass in the universe in the form of PBHs are discussed.Comment: PhD Thesis, Queen Mary, U. of London, Supervisor: Bernard J Carr. (134 pages and 9 figures