The RARE model: a generalized approach to random relaxation processes in disordered systems

This paper introduces and analyses a general statistical model, termed the RARE model, of random relaxation processes in disordered systems. The model considers excitations, that are randomly scattered around a reaction center in a general embedding space. The model's input quantities are the spatial scattering statistics of the excitations around the reaction center, and the chemical reaction rates between the excitations and the reaction center as a function of their mutual distance. The framework of the RARE model is robust, and a detailed stochastic analysis of the random relaxation processes is established. Analytic results regarding the duration and the range of the random relaxation processes, as well as the model's thermodynamic limit, are obtained in closed form. In particular, the case of power-law inputs, which turn out to yield stretched exponential relaxation patterns and asymptotically Paretian relaxation ranges, is addressed in detail.Comment: 10 pages, REVTeX

Poisson-process limit-laws yield Gumbel Max-Min and Min-Max

"A chain is only as strong as its weakest link" says the proverb. But what about a collection of statistically identical chains: How long till all chains fail? The answer to this question is given by the Max-Min of a matrix whose $\left(i,j\right)$ entry is the failure time of link $j$ of chain $i$: take the minimum of each row, and then the maximum of the rows' minima. The corresponding Min-Max is obtained by taking the maximum of each column, and then the minimum of the columns' maxima. The Min-Max applies to the storage of critical data. Indeed, consider multiple backup copies of a set of critical data items, and consider the $\left(i,j\right)$ matrix entry to be the time at which item $j$ on copy $i$ is lost; then, the Min-Max is the time at which the first critical data item is lost. In this paper, we address random matrices whose entries are independent and identically distributed random variables. We establish Poisson-process limit-laws for the row's minima and for the columns' maxima. Then, we further establish Gumbel limit-laws for the Max-Min and for the Min-Max. The limit-laws hold whenever the entries' distribution has a density, and the Gumbel limit-laws yield highly applicable approximation tools and design tools for large random matrices

Gumbel Central Limit Theorem for Max-Min and Min-Max

The Max-Min and Min-Max of matrices arise prevalently in science and engineering. However, in many real-world situations the computation of the Max-Min and Min-Max is challenging as matrices are large and full information about their entries is lacking. Here we take a statistical-physics approach and establish limit-laws -- akin to the Central Limit Theorem -- for the Max-Min and Min-Max of large random matrices. The limit-laws intertwine random-matrix theory and extreme-value theory, couple the matrix-dimensions geometrically, and assert that Gumbel statistics emerge irrespective of the matrix-entries' distribution. Due to their generality and universality, as well as their practicality, these novel results are expected to have a host of applications in the physical sciences and beyond

Shut the Rail: Economic Impacts in Costa Rica

基于哥斯达黎加1995年突发的铁路停运政策，针对哥斯达黎加自1984年到2000年移民模 式的变化，本文进一步讨论了该国铁路基础设施对其移民模式的影响。通过合并代表性的数据库， 并随机抽查国家人口和家庭普查的两个样本。结果显示：铁路设施的出现使个人移民的几率增加 了27.12%；同时也表明：移民还受个人的文化水平，就业以及年龄的影响。此外，还进一步揭 示了铁路系统如何影响移民方向。由此说明了铁路停运政策是该国移民的主要原因。 关This paper estimates the effects of railway infrastructure on migration patterns in Costa Rica during the years 1984 and 2000. It employs a sudden shutdown policy in 1995 as a methodology to identify changes between these two periods. A pooled cross-sectional dataset built with two samples from the National Population and Household Census is employed. Results show how the presence of railway in...学位：金融硕士院系专业：王亚南经济研究院_金融学学号：2772013115460

Evaluación de la calidad alcanzada por los laboratorios clínicos de los hospitales públicos de Quito, posterior a la consecución de la acreditación Canadá

Quality levels in Health Care which are received by users of Public Health System are constantly monitored by administrative part, in order to improve those levels of quality, and satisfying in this ways the internal and external customers’ expectations. Ecuador stars in 2008 a revolutionary change around its Health Care System, changing its curative model by a preventive model according with expectations and regulations created by Primary Health Care Model named as MAIS. Quality certifications achieved by Public Heath Institutions done by Canada international Accreditation (ACI) is the most important advance in search of high quality levels, and permit us to analyze and compare among all public institutions which is the effect of these processes.Los niveles de calidad en la atención sanitaria que reciben los usuarios de los Sistemas de Salud Públicos son objeto constante evaluación por parte de los niveles administrativos, en búsqueda de que estos sean mejorados alcanzando niveles de calidad que satisfagan a los usuarios internos y externos de dichos servicios. Ecuador inicia a partir del año 2008 un cambio en el modelo de atención sanitaria, pasa de modelo curativo a un modelo preventivo; conjuntamente este cambio en la visión surgen profundas modificaciones dentro del Sistema Público de Atención Sanitaria. La certificación de los estándares de calidad alcanzados en las instituciones públicas de Salud, otorgada por Acreditación Canadá Internacional (ACI), consiste uno de los mayores avances en la búsqueda de la calidad en la atención sanitaria por lo que brinda la pauta inicial para analizar y comparar interinstitucionalmente los niveles de impacto ocasionados por este proceso

Proportionate vs disproportionate distribution of wealth of two individuals in a tempered Paretian ensemble

We study the distribution P(\omega) of the random variable \omega = x_1/(x_1 + x_2), where x_1 and x_2 are the wealths of two individuals selected at random from the same tempered Paretian ensemble characterized by the distribution \Psi(x) \sim \phi(x)/x^{1 + \alpha}, where \alpha > 0 is the Pareto index and $\phi(x)$ is the cut-off function. We consider two forms of \phi(x): a bounded function \phi(x) = 1 for L \leq x \leq H, and zero otherwise, and a smooth exponential function \phi(x) = \exp(-L/x - x/H). In both cases \Psi(x) has moments of arbitrary order. We show that, for \alpha > 1, P(\omega) always has a unimodal form and is peaked at \omega = 1/2, so that most probably x_1 \approx x_2. For 0 < \alpha < 1 we observe a more complicated behavior which depends on the value of \delta = L/H. In particular, for \delta < \delta_c - a certain threshold value - P(\omega) has a three-modal (for a bounded \phi(x)) and a bimodal M-shape (for an exponential \phi(x)) form which signifies that in such ensembles the wealths x_1 and x_2 are disproportionately different.Comment: 9 pages, 8 figures, to appear in Physica

Neuromodulación cerebral profunda como opción terapéutica de la enfermedad de parkison idiopático en El Salvador: Informe de casos y evaluación de respuesta clínica

Esta tesis trata sobre la neuromodulación cerebral profunda (NCP) –que es una terapia quirúrgica- como opción para el manejo de la enfermedad de Parkinson (EP) idiopático en El Salvador, en aquellos pacientes que adolecen de esta enfermedad y, sus síntomas ya no son adecuadamente controlados con el manejo farmacológico. Para ello se efectuó un informe de cuatro casos de pacientes que fueron operados en el Hospital de Diagnóstico de la colonia Escalón de El Salvador, que representan el universo de pacientes intervenidos en el país y, se realizó un análisis de serie temporal evaluando la respuesta clínica antes y después del tratamiento. Por otro lado, se cuantificó el número y concentración de medicamentos administrados a cada paciente -antes y después del procedimiento- y se describieron los efectos secundarios de los medicamentos así como también de la NCP