Quasistationarity of continuous-time Markov chains with positive drift

We shall study continuous-time Markov chains on the nonnegative integers which are both irreducible and transient, and which exhibit discernible stationarity before drift to infinity sets in. We will show how this 'quasi' stationary behaviour can be modelled using a limiting conditional distribution: specifically, the limiting state probabilities conditional on not having left 0 for the last time. By way of a dual chain, obtained by killing the original process on last exit from 0, we invoke the theory of quasistationarity for absorbing Markov chains. We prove that the conditioned state probabilities of the original chain are equal to the state probabilities of its dual conditioned on non-absorption, thus allowing us to establish the simultaneous existence and then equivalence, of their limiting conditional distributions. Although a limiting conditional distribution for the dual chain is always a quasistationary distribution in the usual sense, a similar statement is not possible for the original chain.

Further results on the relationship between mu-invariant measures and quasi-stationary distributions for absorbing continuous-time Markov chains

This note considers continuous-time Markov chains whose state space consists of an irreducible class, C, and an absorbing state which is accessible from C. The purpose is to provide results on mu-invariant and mu-subinvariant measures where absorption occurs with probability less than one. In particular, the well-known premise that the mu-invariant measure, m, for the transition rates be finite is replaced by the more natural premise that m be finite with respect to the absorption probabilities. The relationship between mu-invariant measures and quasi-stationary distributions is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.

New methods for determining quasi-stationary distributions for Markov chains

We shall be concerned with the problem of determining quasi-stationary distributions for Markovian models directly from their transition rates Q. We shall present simple conditions for a mu-invariant measure m for Q to be mu-invariant for the transition function, so that if m is finite, it can be normalized to produce a quasi-stationary distribution. (C) 2000 Elsevier Science Ltd. All rights reserved.

Neighborhood and Efficiency in Manufacturing in Brazilian Regions: A Spatial Markov Chain Analysis

This paper analyzes the geography of regional competitiveness in manufacturing in Brazil. The authors estimate stochastic frontiers to calculate regional efficiency of representative firms in 137 regions in the period 2000-2006, in four sectors defined by technological intensity. The efficiency results are analyzed using Markov Spatial Transition Matrices to provide insights into the transition of regions between efficiency levels, considering their local spatial context. The results indicate that geography plays an important role in manufacturing competitiveness. In particular, regions with more competitive neighbors are more likely to improve their relative efficiency (pull effect) over time, and regions with less competitive neighbors are more likely to lose relative efficiency (drag effect). The authors find that the pull effect is stronger than the drag effect.

Characterization of the rat exploratory behavior in the elevated plus-maze with Markov chains

The elevated plus-maze is an animal model of anxiety used to study the effect of different drugs on the behavior of the animal It consists of a plus-shaped maze with two open and two closed arms elevated 50 cm from the floor The standard measures used to characterize exploratory behavior in the elevated plus-maze are the time spent and the number of entries in the open arms In this work we use Markov chains to characterize the exploratory behavior of the rat in the elevated plus-maze under three different conditions normal and under the effects of anxiogenic and anxiolytic drugs The spatial structure of the elevated plus-maze is divided into squares which are associated with states of a Markov chain By counting the frequencies of transitions between states during 5-min sessions in the elevated plus-maze we constructed stochastic matrices for the three conditions studied The stochastic matrices show specific patterns which correspond to the observed behaviors of the rat under the three different conditions For the control group the stochastic matrix shows a clear preference for places in the closed arms This preference is enhanced for the anxiogenic group For the anxiolytic group the stochastic matrix shows a pattern similar to a random walk Our results suggest that Markov chains can be used together with the standard measures to characterize the rat behavior in the elevated plus-maze (C) 2010 Elsevier B V All rights reserved

Similar Markov chains

enin et al. (2000) recently introduced the idea of similarity in the context of birth-death processes. This paper examines the extent to which their results can be extended to arbitrary Markov chains. It is proved that, under a variety of conditions, similar chains are strongly similar in a sense which is described, and it is shown that minimal chains are strongly similar if and only if the corresponding transition-rate matrices are strongly similar. A general framework is given for constructing families of strongly similar chains; it permits the construction of all such chains in the irreducible case.

Path integrals for continuous-time Markov chains

This note presents a method of evaluating the distribution of a path integral for Markov chains on a countable state space.

Set-valued Markov chains and negative semitrajectories of discretized dynamical systems

Computer simulation of dynamical systems involves a phase space which is the finite set of machine arithmetic. Rounding state values of the continuous system to this grid yields a spatially discrete dynamical system, often with different dynamical behaviour. Discretization of an invertible smooth system gives a system with set-valued negative semitrajectories. As the grid is refined, asymptotic behaviour of the semitrajectories follows probabilistic laws which correspond to a set-valued Markov chain, whose transition probabilities can be explicitly calculated. The results are illustrated for two-dimensional dynamical systems obtained by discretization of fractional linear transformations of the unit disc in the complex plane.

Integrals for continuous-time Markov chains

This paper presents a method of evaluating the expected value of a path integral for a general Markov chain on a countable state space. We illustrate the method with reference to several models, including birth-death processes and the birth, death and catastrophe process. (C) 2002 Elsevier Science Inc. All rights reserved.

O censo Suas como processo de aprimoramento e institucionaliza????o da pol??tica de assist??ncia social no Brasil

O Censo Suas ?? um processo de monitoramento que coleta dados por meio de um formul??rio eletr??nico preenchido pelas secretarias e conselhos de Assist??ncia Social. ?? realizado anualmente desde 2007, por meio de uma a????o integrada entre a Secretaria de Assist??ncia Social e a Secretaria de Avalia????o e Gest??o da Informa????o. Esse processo alcan??ou sua maturidade com a incorpora????o de novos question??rios para a coleta de informa????es sobre ??rg??os gestores, Conselhos e entidades privadas de Assist??ncia Social. Em 2010, 99,2% dos munic??pios preencheram 28.519 question??rios. Assim, a Assist??ncia Social aprimorou seu processo de tomada de decis??o, expandindo a rede e a cobertura dos servi??os. Com os indicadores e as metas de desenvolvimento dos Centros de Refer??ncia de Assist??ncia Social (Cras), apurados com base no Censo, foram retroalimentados a????es e projetos de assist??ncia social, institu??dos processos gradativos de adequa????o dos servi??os ??s normas e constitu??dos processos de planejamento para melhoria da gest??o e do controle social do Sistema ??nico de Assist??ncia Social (Suas)

e-Processo: Processo Administrativo Digital

A iniciativa visa ?? extin????o do uso de papel nos processos dentro do ??rg??o p??blico mediante a cria????o do Processo Administrativo Digital (e-Processo). A promo????o da transpar??ncia dos atos p??blicos, com gest??o do conhecimento, maior autonomia e descentraliza????o administrativa, fortalece a democracia,melhora o ambiente de neg??cio e a confian??a no governo. O sistema foi implantado em todas as ??reas de neg??cios de 700 unidades administrativas, com 33 mil servidores conectados nos tr??s ??rg??os p??blicos federais: Receita Federal do Brasil (RFB), Procuradoria da Fazenda Nacional (PFN) e Conselho Administrativo de Recursos Fiscais (Carf). A substitui????o de um documento papel por um documento imagem tem o cond??o de promover no Estado uma verdadeira reengenharia procedimental e administrativa

A hist??ria de dois contratos: como minimizar o risco de se estabelecer um contrato com v??nculo empregat??cio no processo de adquirir bens, contratar servi??os ou implementar um projeto de constru????o

O caso trata da contrata????o de George, pesquisador que prestava servi??os a um ??rg??o p??blico canadense e que, ap??s sofrer um acidente de trabalho, foi informado de que n??o tinha direito ?? cobertura do plano de sa??de dispon??vel aos servidores. Devido ?? precariedade do contrato no qual eram estabelecidas as condi????es da rela????o de trabalho, e de ter sido comprovado que o pesquisador era tratado tal como funcion??rio do minist??rio, George teve direito aos benef??cios a que fazia jus e o ??rg??o foi multado por n??o ter recolhido os valores referentes ?? rela????o trabalhista. Essa situa????o ilustra um breve debate sobre como estabelecer bons contratos com prestadores de servi??o, em especial no que tange a contrata????es de servi??os t??cnicos especializados

Redu????o da taxa de cancelamento de cirurgias atrav??s da otimiza????o do processo assistencial

O Centro Cir??rgico do Hospital de Cl??nicas de Porto Alegre realiza em torno de 46 cirurgias di??rias de m??dia e alta complexidade. O cancelamento de cirurgias gerava insatisfa????o e preju??zo direto ao paciente. O processo assistencial cir??rgico n??o era informatizado, o que dificultava a tomada de decis??o, por n??o dispor de dados fidedignos e abrangentes que mapeassem todos os eventos desse processo. Um trabalho rigoroso e detalhado de identifica????o das atividades, desde o atendimento ambulatorial do paciente cir??rgico at?? a realiza????o da cirurgia, proporcionou a informatiza????o do processo cr??tico, prevendo o registro das informa????es por quem realmente executa cada tarefa. O objetivo de subsidiar a tomada de decis??o foi alcan??ado. O resultado principal esperado ??? reduzir a taxa de cancelamento de cirurgias ??? foi obtido. A solu????o desse desafio simplificou e agilizou os procedimentos, qualificou a assist??ncia e humanizou o atendimento, refletindo diretamente na satisfa????o do paciente

A iniciativa da Delegacia Federal de Agricultura do Mato Grosso do Sul na padroniza????o de procedimentos e no controle de "n??o conformidades" no processo de fiscaliza????o, do Minist??rio da Agricultura e do Abastecimento

A Delegacia Federal de Agricultura/MS- DFA/MS elaborou um manual de procedimento padr??o no processo de fiscaliza????o e criou um in??dito sistema de controle e registro de "n??o conformidades" nos processos de fiscaliza????o, que al??m de n??o trazer nenhum custo extra ?? reparti????o, motiva o trabalho em equipe e ?? melhoria cont??nua nos processos de trabalho. Esta a????o inova, tamb??m, por constituir-se numa ferramenta de trabalho que permite a avalia????o do desempenho institucional e do desempenho individual do servidor, e induz por, conseq????ncia, ao aumento da efici??ncia organizacional