Linear Programming for Large-Scale Markov Decision Problems

We consider the problem of controlling a Markov decision process (MDP) with a large state space, so as to minimize average cost. Since it is intractable to compete with the optimal policy for large scale problems, we pursue the more modest goal of competing with a low-dimensional family of policies. We use the dual linear programming formulation of the MDP average cost problem, in which the variable is a stationary distribution over state-action pairs, and we consider a neighborhood of a low-dimensional subset of the set of stationary distributions (defined in terms of state-action features) as the comparison class. We propose two techniques, one based on stochastic convex optimization, and one based on constraint sampling. In both cases, we give bounds that show that the performance of our algorithms approaches the best achievable by any policy in the comparison class. Most importantly, these results depend on the size of the comparison class, but not on the size of the state space. Preliminary experiments show the effectiveness of the proposed algorithms in a queuing application.Comment: 27 pages, 3 figure

The non-linearity between <ln A> and <Xmax> induced by the acceptance of fluorescence telescopes

The measurement of the average depth of the shower maximum is the most commonly used observable for the possible inference of the primary cosmic-ray mass composition. Currently, different experimental Collaborations process and present their data not in the same way, leading to problems in the comparability and interpretation of the results. Whereas is expected to be proportional to in ideal conditions, we demonstrate that the finite field-of-view of fluorescence telescopes plus the attenuation in the atmosphere can introduce a non-linearity into this relation, which is specific for each particular detector setup

Steering Supply Chains from a Complex Systems Perspective

Purpose The purpose of this research is to systematically review the properties of supply chains demonstrating that they are complex systems, and that the management of supply chains is best achieved by steering rather than controlling these systems toward desired outcomes. Design/methodology/approach The research study was designed as both exploratory and explanatory. Data were collected from secondary sources using a comprehensive literature review process. In parallel with data collection, data were analyzed and synthesized. Findings The main finding is the introduction of an inductive framework for steering supply chains from a complex systems perspective by explaining why supply chains have properties of complex systems and how to deal with their complexity while steering them toward desired outcomes. Complexity properties are summarized in four inter-dependent categories: Structural, Dynamic, Behavioral and Decision making, which together enable the assessment of supply chains as complex systems. Furthermore, five mechanisms emerged for dealing with the complexity of supply chains: classification, modeling, measurement, relational analysis and handling. Originality/value Recognizing that supply chains are complex systems allows for a better grasp of the effect of positive feedback on change and transformation, and also interactions leading to dynamic equilibria, nonlinearity and the role of inter-organizational learning, as well as emerging capabilities, and existing trade-offs and paradoxical tensions in decision-making. It recognizes changing dynamics and the co-evolution of supply chain phenomena in different scales and contexts

Comparision of the estimation of the least square and genetic algorithm throuth serval function in R

R software is considered software in which various available functions make it possible to conduct extensive statistical calculations. Genetic algorithm is a method through which we search for approximate solution in optimization. This article aims at evaluating the functions existed in the R software which are employed for approximate solution in optimization. As a result, there has been produced least squares by usual methods for linear and non-linear models through genetic algorithm in this research.Keywords: Least Squares, Genetic Algorithm, Linear Model, Nonlinear Model, Squares Averag

Novel technique for supernova detection with IceCube

The current supernova detection technique used in IceCube relies on the sudden deviation of the summed photomultiplier noise rate from its nominal value during the neutrino burst, making IceCube a $\approx 3$ Megaton effective detection volume - class supernova detector. While galactic supernovae can be resolved with this technique, the supernova neutrino emission spectrum remains unconstrained and thus presents a limited potential for the topics related to supernova core collapse models. The paper elaborates analytically on the capabilities of IceCube to detect supernovae through the analysis of hits in the detector correlated in space and time. These arise from supernova neutrinos interacting in the instrumented detector volume along single strings. Although the effective detection volume for such coincidental hits is much smaller ($\gtrsim 35\,$kton, about the scale of SuperK), a wealth of information is obtained due to the comparatively low coincidental noise rate. We demonstrate that a neutrino flux from a core collapse supernova will produce a signature enabling the resolution of rough spectral features and, in the case of a strong signal, providing indication on its location. We further discuss the enhanced potential of a rather modest detector extension, a denser array in the center of IceCube, within our one dimensional analytic calculation framework. Such an extension would enable the exploration of the neutrino sky above a few GeV and the detection of supernovae up to a few 100's of kilo parsec. However, a $3-4\,$Mpc detection distance, necessary for routine supernova detection, demands a significant increase of the effective detection volume and can be obtained only with a more ambitious instrument, particularly the boosting of sensor parameters such as the quantum efficiency and light collection area.Comment: 12 p., 10 fi

Aplicações da aproximação quase-newtoniana da Relatividade Geral a problemas em astrofísica

Dissertação de Mestrado apresentada ao Programa de Pós- Graduação em Fı́sica Aplicada da Universidade Federal da Integração Latino-Americana (PPGFISA-UNILA) como parte dos requisitos ncessários para obtenção do tı́tulo de Mestre em (Fı́sica). Orientador: Prof. Dr. Abraão Jessé Capistrano de Souza Coorientador: Prof. Dr. Luı́s Antonio CabralNo presente trabalho, investigamos o movimento lento na Relatividade Geral (RG) sob ação de um campo gravitacional arbitrário. Trata-se do uso de uma aproximação conhecida por aproximação quase Newtoniana (NNA). Nossa intenção é apresentar um novo paradigma para a Astrofísica, uma vez que o modelo pode auxiliar no entendimento da gravidade na cinemática e dinâmica de corpos celestes, mas não representa uma modificação da RG. Primeiro, usamos a métrica de Weyl para analisar o desvio do periastro de 34 exoplanetas. Em segundo lugar, a métrica oblata de Zipoy, em termos da solução do monopólo, também, faz parte do escopo deste trabalho. Mostramos que a métrica de Zipoy pode ser muito útil para propósitos astrofísicos, mesmo quando comparada a solução padrão de Einstein ou via formalismo pós-newtoniano parametrizado (PPN), porque satisfaz o valor da precessão observada para o periélio de Mercúrio, a solução fornece órbitas elípticas e, também, permite o estudo de precessões retrógradas.In the present work, we investigate the slow motion in General Relativity (GR) under an arbitrary gravitational field. It is about the use of an approximation known by nearly Newtonian approximation (NNA). Our intent is to present a new paradigm for Astrophy- sics, since the model can assist the understanding of gravity in kinematic and dynamics of celestial bodies but does not represent a modification of GR. First, we use Weyl’s me- tric to analyze the deviation of periastron of 34 exoplanets. Secondly, the oblate Zipoy’s metric, in terms by monopole solution, is also part of the scope of this work. We show that Zipoy’s metric may be very useful for astrophysical purposes, even when compared to Einstein’s standard solution or by formalism of parameterized post-Newtonian (PPN), because it satisfies the observed precession value for Mercury’s perihelion, the solution provides elliptical orbits and also allows the study of retrograde precessio

Effects of ovarian varicose vein on mitochondrial structure, malondialdehyde and prooxidants - Antioxidants balance in rat ovaries Efectos de las Venas Ováricas Varicosas sobre la Estructura Mitocondrial, Niveles de Malondialdehído y Balance Prooxidantes-antioxidantes en Ovarios de Ratas

Oxidative stress is increased in varicose veins. Many studies have implicated oxidative stress in the pathogenesis of infertility causing diseases of the female reproductive tract. The aim of this study was to determine whether varicocele can cause raised levels of reactive oxygen species and denaturation of mitochondrial structure in ovaries of female rats or not. In each experimental study, 15 weaning-age female rats were divided equally in 3 groups: Unilateral Varicose Vein (A), Sham (B) and Control (C) groups. Mitochondrial structure and malondialdehyde levels as a product of lipid peroxidation and Prooxidants-Antioxidants Balance were evaluated 60 days after intervention in proestrus stage. Comparisons between groups were made by the measured test. After 2 months, our results showed that mitochondrial structure ultra-structurally was denatured with histologic examination, malondialdehyde and prooxidants-antioxidants balance levels of left ovaries increased significantly in varicocele group compared to control and sham groups (P�0.05). In the right side, malondialdehyde increased significantly, but in prooxidantsantioxidants balance levels, there is no significant differences between groups. The data of control and sham groups were the same. These findings may support the concept that increased levels of malondialdehyde and PAB in varicocele may cause negative effects on fertility, so using antioxidants maybe useful. © 2015, International Journal of Morphology. All rights reserved