Mercado spot de energía y modelo alternativo para la fijación de un precio eficiente

La resolución CREG 051 de 2009 es la última resolución vigente sobre el despacho ideal del MEM (Mercado de energía mayorista), además del cálculo del precio de bolsa de energía -- Esta metodología indica que la remuneración de los recursos térmicos en pruebas se realiza a un precio superior al precio marginal del sistema, lo cual genera incrementos en el precio de bolsa del mercado spot -- Se plantea una metodología alternativa para la remuneración de esta generación en pruebas, con el fin de generar los incentivos adecuados y obtener precios del mercado eficiente

A framework for epidemic spreading in multiplex networks of metapopulations

We propose a theoretical framework for the study of epidemics in structured metapopulations, with heterogeneous agents, subjected to recurrent mobility patterns. We propose to represent the heterogeneity in the composition of the metapopulations as layers in a multiplex network, where nodes would correspond to geographical areas and layers account for the mobility patterns of agents of the same class. We analyze both the classical Susceptible-Infected-Susceptible and the Susceptible-Infected-Removed epidemic models within this framework, and compare macroscopic and microscopic indicators of the spreading process with extensive Monte Carlo simulations. Our results are in excellent agreement with the simulations. We also derive an exact expression of the epidemic threshold on this general framework revealing a non-trivial dependence on the mobility parameter. Finally, we use this new formalism to address the spread of diseases in real cities, specifically in the city of Medellin, Colombia, whose population is divided into six socio-economic classes, each one identified with a layer in this multiplex formalism.Comment: 13 pages, 11 figure

Characteristics of and determinants of the density of contributions in a Private Social Security System

This paper investigates previously unresearched issues pertaining to the well-known Chilean innovations in Social Security. Previous empirical studies of the Chilean system used aggregate and macro data, without attention to individual heterogeneity. This study uses new household survey data, linked with Social Security records for over 20 years, to analyze selected reform issues related to social security coverage and the density and continuity of contributions to the social security system. The results lead to a better understanding of the participation determinants and the distributional aspects of the Chilean system, lay the groundwork for policy changes, and illuminate implications of the system reforms for other countries.

Simulation of genome-wide evolution under heterogeneous substitution models and complex multispecies coalescent histories

Genomic evolution can be highly heterogeneous. Here, we introduce a new framework to simulate genome-wide sequence evolution under a variety of substitution models that may change along the genome and the phylogeny, following complex multispecies coalescent histories that can include recombination, demographics, longitudinal sampling, population subdivision/species history, and migration. A key aspect of our simulation strategy is that the heterogeneity of the whole evolutionary process can be parameterized according to statistical prior distributions specified by the user. We used this framework to carry out a study of the impact of variable codon frequencies across genomic regions on the estimation of the genome-wide nonsynonymous/synonymous ratio. We found that both variable codon frequencies across genes and rate variation among sites and regions can lead to severe underestimation of the global dN/dS values. The program SGWE—Simulation of Genome-Wide Evolution—is freely available from http://code.google.com/p/sgwe-project/, including extensive documentation and detailed examples.Ministerio de Ciencia e Innovación | Ref. JCI-2011-1045

From Giant H II regions and H II galaxies to globular clusters and compact dwarf ellipticals

Massive starforming regions like Giant HII Regions (GHIIR) and HII Galaxies (HIIG) are emission line systems ionized by compact young massive star clusters (YMC) with masses ranging from $10^4$M$_\odot$ to $10^8$M$_\odot$. We model the photometric and dynamical evolution over a Hubble time of the massive gravitationally bound systems that populate the tight relation between absolute blue magnitude and velocity dispersion ($M_{B}-\sigma$) of GHIIR and HIIG and compare the resulting relation with that one of old stellar systems: globular clusters, elliptical galaxies, bulges of spirals. After 12~Gyr of evolution their position on the $\sigma$ vs. M$_B$ plane coincides -- depending on the initial mass -- either with the globular clusters for systems with initial mass $M < 10^6$M$_\odot$ or with a continuation of the ellipticals, bulges of spirals and ultracompact dwarfs for YMC with $M >10^6$M$_\odot$. The slope change in the $M_{B}-\sigma$ and $M_B$-size relations at cluster masses around $10^6$M$_\odot$ is due to the larger impact of the dynamical evolution on the lower mass clusters. We interpret our result as an indication that the YMC that ionize GHIIR and HIIG can evolve to form globular clusters and ultra compact dwarf ellipticals in about 12 Gyr so that present day globular clusters and ultra compact dwarf ellipticals may have formed in conditions similar to those observed in today GHIIR and HIIG.Comment: 11 pages, 6 figures, accepted for publication in MNRA

The Chilean Pension Reform Turns 25: Lessons From the Social Protection Survey

In 1980, Chile dramatically reformed its retirement system, replacing what was an old insolvent PAYGO program with a new structure that relies heavily on funded defined contribution individual accounts. In addition, eligibility and benefit requirements were standardized, and a safety net for old-age poverty was strengthened. Twenty-five years after this reform, the Chilean model is being re-assessed, in terms of coverage, contribution, investment, and retirement benefit outcomes. This paper introduces a recently-developed longitudinal survey of individual respondents in Chile, the Social Protection Survey (or Encuesta de Previsión Social, EPS), and illustrates some uses of this survey for microeconomic analysis of key aspects of the Chilean system.

On the Generalized Ratio of Uniforms as a Combination of Transformed Rejection and Extended Inverse of Density Sampling

Documento depositado en el repositorio arXiv.org. Versión: arXiv:1205.0482v6 [stat.CO]In this work we investigate the relationship among three classical sampling techniques: the inverse of density (Khintchine's theorem), the transformed rejection (TR) and the generalized ratio of uniforms (GRoU). Given a monotonic probability density function (PDF), we show that the transformed area obtained using the generalized ratio of uniforms method can be found equivalently by applying the transformed rejection sampling approach to the inverse function of the target density. Then we provide an extension of the classical inverse of density idea, showing that it is completely equivalent to the GRoU method for monotonic densities. Although we concentrate on monotonic probability density functions (PDFs), we also discuss how the results presented here can be extended to any non-monotonic PDF that can be decomposed into a collection of intervals where it is monotonically increasing or decreasing. In this general case, we show the connections with transformations of certain random variables and the generalized inverse PDF with the GRoU technique. Finally, we also introduce a GRoU technique to handle unbounded target densities

Minimality of the D\mathcal D-groupoid of symmetries of a projective structure

In this article we study Kummer's $\mathcal D$-groupoid, which is the groupoid of symmetries of a meromorphic projective structure. We give necessary and sufficient conditions for its minimality, in the sense of not having infinite sub-$\mathcal D$-groupoids. The condition that we find turns out to be equivalent to the strong minimality of the non-linear Schwarzian equation and the non-integrability by means of Liouvillian functions of the linear Schwarzian equation.Comment: 16 page

An independent determination of the local Hubble constant

The relationship between the integrated H$\beta$ line luminosity and the velocity dispersion of the ionized gas of HII galaxies and giant HII regions represents an exciting standard candle that presently can be used up to redshifts z ~ 4. Locally it is used to obtain precise measurements of the Hubble constant by combining the slope of the relation obtained from nearby ($z \leq$ 0.2) HII galaxies with the zero point determined from giant HII regions belonging to an `anchor sample' of galaxies for which accurate redshift-independent distance moduli are available. We present new data for 36 giant HII regions in 13 galaxies of the anchor sample that includes the megamaser galaxy NGC 4258. Our data is the result of the first four years of observation of our primary sample of 130 giant HII regions in 73 galaxies with Cepheid determined distances. Our best estimate of the Hubble parameter is $71.0\pm2.8(random)\pm2.1(systematic)$ km /s Mpc This result is the product of an independent approach and, although at present less precise than the latest SNIa results, it is amenable to substantial improvement.Comment: 30 pages, 28 figures, Accepted to be published in MNRA