Stochastic lattice gas model describing the dynamics of the SIRS epidemic process

We study a stochastic process describing the onset of spreading dynamics of an epidemic in a population composed of individuals of three classes: susceptible (S), infected (I), and recovered (R). The stochastic process is defined by local rules and involves the following cyclic process: S -> I -> R -> S (SIRS). The open process S -> I -> R (SIR) is studied as a particular case of the SIRS process. The epidemic process is analyzed at different levels of description: by a stochastic lattice gas model and by a birth and death process. By means of Monte Carlo simulations and dynamical mean-field approximations we show that the SIRS stochastic lattice gas model exhibit a line of critical points separating the two phases: an absorbing phase where the lattice is completely full of S individuals and an active phase where S, I and R individuals coexist, which may or may not present population cycles. The critical line, that corresponds to the onset of epidemic spreading, is shown to belong in the directed percolation universality class. By considering the birth and death process we analyze the role of noise in stabilizing the oscillations. (C) 2009 Elsevier B.V. All rights reserved.

CRITICAL BEHAVIOR AND THRESHOLD OF COEXISTENCE OF A PREDATOR-PREY STOCHASTIC MODEL IN A 2D LATTICE

We investigate the critical behavior of a stochastic lattice model describing a predator-prey system. By means of Monte Carlo procedure we simulate the model defined on a regular square lattice and determine the threshold of species coexistence, that is, the critical phase boundaries related to the transition between an active state, where both species coexist and an absorbing state where one of the species is extinct. A finite size scaling analysis is employed to determine the order parameter, order parameter fluctuations, correlation length and the critical exponents. Our numerical results for the critical exponents agree with those of the directed percolation universality class. We also check the validity of the hyperscaling relation and present the data collapse curves.

Soluble one-dimensional particle conservation models with infinitely many absorbing states

Particle conservation lattice-gas models with infinitely many absorbing states are studied on a one-dimensional lattice. As one increases the particle density, they exhibit a phase transition from an absorbing to an active phase. The models are solved exactly by the use of the transfer matrix technique from which the critical behavior was obtained. We have found that the exponent related to the order parameter, the density of active sites, is 1 for all studied models except one of them with exponent 2.

An extinction-survival-type phase transition in the probabilistic cellular automaton p182-q200

We investigate the critical behaviour of a probabilistic mixture of cellular automata (CA) rules 182 and 200 (in Wolfram`s enumeration scheme) by mean-field analysis and Monte Carlo simulations. We found that as we switch off one CA and switch on the other by the variation of the single parameter of the model, the probabilistic CA (PCA) goes through an extinction-survival-type phase transition, and the numerical data indicate that it belongs to the directed percolation universality class of critical behaviour. The PCA displays a characteristic stationary density profile and a slow, diffusive dynamics close to the pure CA 200 point that we discuss briefly. Remarks on an interesting related stochastic lattice gas are addressed in the conclusions.

Critical behavior of a contact process with aperiodic transition rates

We performed Monte Carlo simulations to investigate the steady-state critical behavior of a one-dimensional contact process with an aperiodic distribution of rates of transition. As in the presence of randomness, spatial fluctuations can lead to changes of critical behavior. For sufficiently weak fluctuations, we give numerical evidence to show that there is no departure from the universal critical behavior of the underlying uniform model. For strong spatial fluctuations, the analysis of the data indicates a change of critical universality class.

A conformal invariant growth model

We present a one-parameter extension of the raise and peel one-dimensional growth model. The model is defined in the configuration space of Dyck (RSOS) paths. Tiles from a rarefied gas hit the interface and change its shape. The adsorption rates are local but the desorption rates are non-local; they depend not only on the cluster hit by the tile but also on the total number of peaks (local maxima) belonging to all the clusters of the configuration. The domain of the parameter is determined by the condition that the rates are non-negative. In the finite-size scaling limit, the model is conformal invariant in the whole open domain. The parameter appears in the sound velocity only. At the boundary of the domain, the stationary state is an adsorbing state and conformal invariance is lost. The model allows us to check the universality of non-local observables in the raise and peel model. An example is given.

A pattern recognition approach to complex networks

Complex networks exist in many areas of science such as biology, neuroscience, engineering, and sociology. The growing development of this area has led to the introduction of several topological and dynamical measurements, which describe and quantify the structure of networks. Such characterization is essential not only for the modeling of real systems but also for the study of dynamic processes that may take place in them. However, it is not easy to use several measurements for the analysis of complex networks, due to the correlation between them and the difficulty of their visualization. To overcome these limitations, we propose an effective and comprehensive approach for the analysis of complex networks, which allows the visualization of several measurements in a few projections that contain the largest data variance and the classification of networks into three levels of detail, vertices, communities, and the global topology. We also demonstrate the efficiency and the universality of the proposed methods in a series of real-world networks in the three levels.

Thermal dependence of the zero-bias conductance through a nanostructure

We show that the conductance of a quantum wire side-coupled to a quantum dot, with a gate potential favoring the formation of a dot magnetic moment, is a universal function of the temperature. Universality prevails even if the currents through the dot and the wire interfere. We apply this result to the experimental data of Sato et al. (Phys. Rev. Lett., 95 (2005) 066801). Copyright (C) EPLA, 2009

Henon-like maps with arbitrary stationary combinatorics

We extend the renormalization operator introduced in [A. de Carvalho, M. Martens and M. Lyubich. Renormalization in the Henon family, I: universality but non-rigidity. J. Stat. Phys. 121(5/6) (2005), 611-669] from period-doubling Henon-like maps to Henon-like maps with arbitrary stationary combinatorics. We show that the renonnalization picture also holds in this case if the maps are taken to be strongly dissipative. We study infinitely renormalizable maps F and show that they have an invariant Cantor set O on which F acts like a p-adic adding machine for some p > 1. We then show, as for the period-doubling case in the work of de Carvalho, Martens and Lyubich [Renormalization in the Henon family, I: universality but non-rigidity. J. Stat. Phys. 121(5/6) (2005), 611-669], that the sequence of renormalizations has a universal form, but that the invariant Cantor set O is non-rigid. We also show that O cannot possess a continuous invariant line field.

Utilizing Remote Sensing Imagery to Monitor Vegetation Change within World Heritage Sites

ABSTRACT World Heritage sites provide a glimpse into the stories and civilizations of the past. There are currently 1007 unique World Heritage properties with 779 being classified as cultural sites, 197 as natural sites, and 31 falling into the categories of both cultural and natural sites (UNESCO & World Heritage Centre, 1992-2015). However, of these 1007 World Heritage sites, at least 46 are categorized as in danger and this number continues to grow. These unique and irreplaceable sites are exceptional because of their universality. Consequently, since World Heritage sites belong to all the people of the world and provide inspiration and admiration to all who visit them, it is our responsibility to help preserve these sites. The key form of preservation involves the individual monitoring of each site over time. While traditional methods are still extremely valuable, more recent advances in the field of geographic and spatial technologies including geographic information systems (GIS), laser scanning, and remote sensing, are becoming more beneficial for the monitoring and overall safeguarding of World Heritage sites. Through the employment and analysis of more accurately detailed spatial data, World Heritage sites can be better managed. There is a strong urgency to protect these sites. The purpose of this thesis is to describe the importance of taking care of World Heritage sites and to depict a way in which spatial technologies can be used to monitor and in effect preserve World Heritage sites through the utilization of remote sensing imagery. The research conducted in this thesis centers on the Everglades National Park, a World Heritage site that is continually affected by changes in vegetation. Data used include Landsat satellite imagery that dates from 2001-2003, the Everglades' boundaries shapefile, and Google Earth imagery. In order to conduct the in-depth analysis of vegetation change within the selected World Heritage site, three main techniques were performed to study changes found within the imagery. These techniques consist of conducting supervised classification for each image, incorporating a vegetation index known as Normalized Vegetation Index (NDVI), and utilizing the change detection tool available in the Environment for Visualizing Images (ENVI) software. With the research and analysis conducted throughout this thesis, it has been shown that within the three year time span (2001-2003), there has been an overall increase in both areas of barren soil (5.760%) and areas of vegetation (1.263%) with a decrease in the percentage of areas classified as sparsely vegetated (-6.987%). These results were gathered through the use of the maximum likelihood classification process available in the ENVI software. The results produced by the change detection tool which further analyzed vegetation change correlate with the results produced by the classification method. As well, by utilizing the NDVI method, one is able to locate changes by selecting a specific area and comparing the vegetation index generated for each date. It has been found that through the utilization of remote sensing technology, it is possible to monitor and observe changes featured within a World Heritage site. Remote sensing is an extraordinary tool that can and should be used by all site managers and organizations whose goal it is to preserve and protect World Heritage sites. Remote sensing can be used to not only observe changes over time, but it can also be used to pinpoint threats within a World Heritage site. World Heritage sites are irreplaceable sources of beauty, culture, and inspiration. It is our responsibility, as citizens of this world, to guard these treasures.

Parameterization Of Turbulence Models Using 3DVAR Data Assimilation

In this research the 3DVAR data assimilation scheme is implemented in the numerical model DIVAST in order to optimize the performance of the numerical model by selecting an appropriate turbulence scheme and tuning its parameters. Two turbulence closure schemes: the Prandtl mixing length model and the two-equation k-ε model were incorporated into DIVAST and examined with respect to their universality of application, complexity of solutions, computational efficiency and numerical stability. A square harbour with one symmetrical entrance subject to tide-induced flows was selected to investigate the structure of turbulent flows. The experimental part of the research was conducted in a tidal basin. A significant advantage of such laboratory experiment is a fully controlled environment where domain setup and forcing are user-defined. The research shows that the Prandtl mixing length model and the two-equation k-ε model, with default parameterization predefined according to literature recommendations, overestimate eddy viscosity which in turn results in a significant underestimation of velocity magnitudes in the harbour. The data assimilation of the model-predicted velocity and laboratory observations significantly improves model predictions for both turbulence models by adjusting modelled flows in the harbour to match de-errored observations. 3DVAR allows also to identify and quantify shortcomings of the numerical model. Such comprehensive analysis gives an optimal solution based on which numerical model parameters can be estimated. The process of turbulence model optimization by reparameterization and tuning towards optimal state led to new constants that may be potentially applied to complex turbulent flows, such as rapidly developing flows or recirculating flows.

O global e o contextual no aprendizado gerencial de multinacionais: uma perspectiva brasileira

The major purpose of this thesis is to verify, from a Brazilian perspective, how global and contextual issues influence the management learning in Multinationals. The management learning derived from the interaction of holding and sidiaries/colligates of Multinational corporation is supposed to be subject to convergent and divergent forces, the former related to global and standardized organizational practices, and the latter, is seen as a social practice subject to cultural and organizational singularities. A model was constructed to relate the dichotomy between the universality of the management practices and technologies and the particularity of the contexts where they operate, to the dichotomy between the singularities in organization and national level. This model is composed of the international, global, managerial and inter-organizational dimensions related, respectively, to the cultural and political diversity; to the universal forces of practices and values; to the managerial capabilities and resources in the organization, consolidated as best practices and to the interaction between holding and subsidiaries and the resulted learning. The combined result of these dimensions influences the knowledge flow and the learning derived from it. The field research was constituted of five cases of internationalized Brazilian firms, with a solid experience in their management systems. The main subjects of this study were executives and ofessionals/managers who respond to the management development. The data were first collected in the headquarters and complemented with visits to subsidiaries/joint ventures in other countries, in loco or with expatriated people who return to Brazil. The central supposition was validated. So, the management learning ¿ is driven by the global capitalism practices and by the global culture where they are immersed, reproducing a hegemonic vision and a common language (global dimension); ¿ incorporates the more propagated and dominant managerial values, although there are some variations when they are applied in the subsidiaries/joint ventures; is the product of the assimilation of international recognized and planned managerial practices, with the acculturation power, although not completely; is the result mainly of the managerial practice in work; is impacted not only by cross-cultural and managerial factors, but also by the business environment of the firm; is given according to the capabilities and resources in the organization, guiding the form of assimilation of practices and technologies, with global application or not (managerial dimension); ¿ is affected by the cross-cultural diversity involving the countries of the holding and the subsidiaries/joint ventures where the firm is and is given as a reproduction of the political context of the holding and subsidiaries countries (international dimension); ¿ faces aligned concurrent institutional pressures between corporate or global systems, practices of other subsidiaries/joint ventures and local practices; is more difficult to reach when there is not permeability between organizational cultures and identities of a Multinational firm; is affected by how much the relationship process across these unities is self-referenced; is facilitated by the construction and improvement of the knowledge network (interorganizational dimension). Finally some contributions of this study are exposed, including extensions of the proposed model and suggestions, recommendations for future research.

As novas doutrinas de Administração Pública e os seus reflexos nos controles e na auditoria de desempenho dos programas governamentais

The developed democracies only have results or crystallise, when the exercise of the government policies has two dimensions: the first one, is the dimension of the government decisions making: in which, the governor accomplishes the priorities and orientations submitted to the population by electoral decisions. Then the second dimension, is the functionality of the State: capable to transform policies into convergent actions for accomplishment of the negotiated results. The consolidation of the democracy and the consequent increase of the social demand by decisions and public and government lawsuits, able to generate results that attend collectively the different levels of the society and able to aggregate and articulate additional values to their interests, imposes to the public sector administration, great challenges of public policies. Nowadays, the indispensable condition to guarantee a minimum governmental benchmark, it to overcome these challenges, in the plan of the public administration, demanded for the promotion of the economic development, in the democratic scope, to reach the politician-institutional values of the society. However, It is undeniable, the universality of the challenges of public administration that consequently, are the effects of modern administrative systems. To attempt the best result, the mast satisfy the attributes of speed, flexibility, integration and innovation, amongst others. The diffusion of guided doctrines of public management by results is reflecting in the institutionalization of new types of bureaucratic activities and amongst this context, it is distinguished as a basic importance of what we call Performance Audit. This work intends to describe how the control organs and especially the Accounts Court of the Union, the sensitive demands of the society, and attending to new constitutional order, they are structuring itself to face the new organizational and institutional challenges, in consequence of the gradual redefinition of your task, more and more liable uncertainties, current of the intimate nature of the performance audit, in development, face the traditional audit, which characterizes them in general. Therefore, the main goal of this these, is the analysis of the organizational challenges and consequently ,the lawsuits changes of the organizational structures faced in general by the Brazilian¿s Accounts Courts, which we believe, will help to elaborate paths of propulsive evaluating and restrictive elements to the innovations that are intended to introduce the systems of necessary control in the evaluation of government programs.

Programa compartilhar/cheque cidadão: o difícil equacionamento entre carências e direitos

o presente estudo buscou verificar se o programa de garantia de renda mínima instituído no estado do Rio de Janeiro - Programa Compartilhar/Cheque Cidadão - se constitui como um programa social alicerçado na ótica dos direitos de cidadania ou, configura-se, conforme amplas denúncias, como uma política assistencialista e clientelista. Para tanto, efetuamos um estudo de campo eminentemente qualitativo que tencionou capturar a riqueza dos depoimentos prestados por beneficiários do Programa, bem como representantes de instituições religiosas de diferentes credos. Partimos do pressuposto que a pobreza é uma situação antagônica ao direito como conceito e como categoria. Deste ponto de vista, consideramos que o conceito de exclusão social - que, em última análise, configura-se como a principal justificativa para a implantação de programas com este perfil no Brasil - hoje se confronta diretamente com a concepção de universalidade e, com ela, a dos direitos sociais e de cidadania. Os resultados encontrados favorecem uma visão do Programa na qual a lógica da ajuda e da benemerência se sobrepõe à percepção dos direitos e os beneficiários se vêem como carentes e necessitados, não como cidadãos.

A política pública de saúde no Brasil: dilemas e desafios para a institucionalização do SUS

A presente dissertação procura analisar as condições de implantação do Sistema Único de Saúde, identificando dilemas e desafios para a institucionalização do SUS. O estudo apresenta uma síntese histórica da Política Pública de Saúde no Brasil, ressaltando as dicotomias entre as ações de natureza preventiva, patrocinadas ao longo do tempo pelo Ministério da Saúde, e as de natureza assistencial, afetas ao Ministério da Previdência Social. Nesta perspectiva, o resgate do processo de formulação e implementação das ações integradas e descentralizadas de saúde comparece como de fundamental importância para a consolidação dos pressupostos do SUS, baseados nas diretr;zes constitucionais de universalidade, integralidade, descentralização e participação da comunidade na gestão do Sistema. Os limites desta consolidação são medidos através da verificação das competências das diferentes esferas de governo; do exercício do controle social pela população; e, das possibilidades de financiamento do sistema.