893 resultados para Two-stage MCMC method


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This dissertation investigates how credit institutions’ market power limits the effects of creditor protection rules on the interest rate and the spread of bank loans. We use the Brazilian Bankruptcy Reform of June/2005 (BBR) as a legal event affecting the institutional environment of the Brazilian credit market. The law augments creditor protection and aims to improve the access of firms to the credit market and to reduce the cost of borrowing. Either access to credit or the credit cost are also determined by bank industry competition and the market power of suppliers of credit. We derive a simple economic model to study the effect of market power interacting with cost of lending. Using an accounting and operations dataset from July/2004 to December/2007 provided by the Brazilian Central Bank, we estimate that the lack of competition in the bank lending industry hinders the potential reducing effect of the BBR on the interest rate of corporate loans by approximately 30% and on the spread by approximately 23%. We also find no statistical evidence that the BBR affected the concentration level of the Brazilian credit market. We present a brief report on bankruptcy reforms around the world, the changes in the Brazilian legislation and on some recent related articles in our introductory chapter. The second chapter presents the economic model and the testable hypothesis on how the lack of competition in the lending market limits the effects of improved creditor protection. In this chapter, we introduce our empirical strategy using a differences-in-differences model and we estimate the limiting effect of market power on the BBR’s potential to reduce interest rates and on the spread of bank loans. We use the BBR as an exogenous event that affects collateralized corporate loans (treatment group) but that does not affect clean consumer loans (control group) to identify these effects, using different concentration measures. In Chapter 3, we propose a two-stage empirical strategy to handle the H–Statistics proposed by Panzar and Rosse as a measure of market competition. We estimate the limiting effects of the lack of competition in replacing the concentration statistics by the H–Statistics. Chapter 4 presents a structural break test of the concentration index and checks if the BBR affects the dynamic evolution of the concentration index.

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Os reflexos da tributação sobre o setor elétrico ultrapassam as questões meramente arrecadatórias de estados, municípios e União, envolvem toda a produção do país e o bem-estar de sua população. Neste contexto, e com o intuito de trazer as questões de eficiência e redistributividade ao ambiente de tributação de energia elétrica, o presente trabalho pretende apresentar um panorama da tributação atual do consumo residencial de energia elétrica, principalmente em relação ao ICMS, juntamente com um cálculo simplificado de alíquotas considerando dois modelos de tributação ótima, estabelecidos por F. R. Ramsey e Diamond e Mirrlees, a partir dos quais é possível realizar comparações em relação ao modelo atual e sintetizar uma visão nacional de uma tributação realizada em sua maior parte regionalmente. O primeiro modelo considera apenas eficiência na definição das alíquotas aplicadas aos produtos, partindo da premissa de que todos os consumidores são idênticos e não há preocupações com equidade. As elasticidades necessárias para aplicação do critério de Ramsey são estimadas a partir de dados em painel das 64 distribuidoras de energia elétrica do país, utilizando um modelo em dois estágios com variável instrumental. O segundo modelo, proposto por Diamond e Mirrlees, incorpora a equidade na modelagem, introduzindo a diferenciação entre os indivíduos.

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This article proposes an alternative methodology for estimating the effects of non-tariff measures on trade flows, based on the recent literature on gravity models. A two-stage Heckman selection model is applied to the case of Brazilian exports, where the second stage gravity equation is theoretically grounded on the seminal Melitz model of heterogeneous firms. This extended gravity equation highlights the role played by zero trade flows as well as firm heterogeneity in explaining bilateral trade among countries, two factors usually omitted in traditional gravity specifications found in previous literature. Last, it also proposes a economic rationale for the effects of NTM on trade flows, helping to shed some light on its main operating channels under a rather simple Cournot’s duopolistic competition framework

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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High amylose was cross-linked with sodium trimetaphosphate (STMP) using 2% and 4% solutions of NaOH at room temperature with reaction contact times of 0.5, 1, 2 and 4 h. The different polymers obtained were analyzed by FT IR, C-13 and P-31 solid state NMR, SEM and C, H and P elemental analysis. The results were used to propose a two-stage mechanism for phosphate incorporation, the first being kinetically controlled. (C) 2008 Elsevier Ltd. All rights reserved.

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Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2x10(9) to about 0.2x10(9) cm(-3) as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E(G), and the surface resistivity, rho(s), fall with increasing P. E(G) and rho(s) are in the ranges of about 2.0-1.3 eV and 10(14)-10(16) Omega/square, respectively. The plasma power also influences the film self-bias, V(b), via a linear dependence, and the effect of V(b) on ion bombardment during growth is addressed together with variation in the relative densities of sp(2) and sp(3) bonds in the films as determined by Raman spectroscopy.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In this paper an efficient algorithm for probabilistic analysis of unbalanced three-phase weakly-meshed distribution systems is presented. This algorithm uses the technique of Two-Point Estimate Method for calculating the probabilistic behavior of the system random variables. Additionally, the deterministic analysis of the state variables is performed by means of a Compensation-Based Radial Load Flow (CBRLF). Such load flow efficiently exploits the topological characteristics of the network. To deal with distributed generation, a strategy to incorporate a simplified model of a generator in the CBRLF is proposed. Thus, depending on the type of control and generator operation conditions, the node with distributed generation can be modeled either as a PV or PQ node. To validate the efficiency of the proposed algorithm, the IEEE 37 bus test system is used. The probabilistic results are compared with those obtained using the Monte Carlo method.

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In this work, we propose a two-stage algorithm for real-time fault detection and identification of industrial plants. Our proposal is based on the analysis of selected features using recursive density estimation and a new evolving classifier algorithm. More specifically, the proposed approach for the detection stage is based on the concept of density in the data space, which is not the same as probability density function, but is a very useful measure for abnormality/outliers detection. This density can be expressed by a Cauchy function and can be calculated recursively, which makes it memory and computational power efficient and, therefore, suitable for on-line applications. The identification/diagnosis stage is based on a self-developing (evolving) fuzzy rule-based classifier system proposed in this work, called AutoClass. An important property of AutoClass is that it can start learning from scratch". Not only do the fuzzy rules not need to be prespecified, but neither do the number of classes for AutoClass (the number may grow, with new class labels being added by the on-line learning process), in a fully unsupervised manner. In the event that an initial rule base exists, AutoClass can evolve/develop it further based on the newly arrived faulty state data. In order to validate our proposal, we present experimental results from a level control didactic process, where control and error signals are used as features for the fault detection and identification systems, but the approach is generic and the number of features can be significant due to the computationally lean methodology, since covariance or more complex calculations, as well as storage of old data, are not required. The obtained results are significantly better than the traditional approaches used for comparison

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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O objetivo deste estudo foi apresentar e discutir a utilização das medidas de associação: razão de chances e razão de prevalências, em dados obtidos de estudo transversal realizado em 2001-2002, utilizando-se amostra estratificada por conglomerados em dois estágios (n=1.958). As razões de chances e razões de prevalências foram estimadas por meio de regressão logística não condicional e regressão de Poisson, respectivamente, utilizando-se o pacote estatístico Stata 7.0. Intervalos de confiança e efeitos do desenho foram considerados na avaliação da precisão das estimativas. Dois desfechos do estudo transversal com diferentes níveis de prevalência foram avaliados: vacinação contra influenza (66,1%) e doença pulmonar referida (6,9%). Na situação em que a prevalência foi alta, as estimativas das razões de prevalência foram mais conservadoras com intervalos de confiança menores. Na avaliação do desfecho de baixa prevalência, não se observaram grandes diferenças numéricas entre as estimações das razões de chances e razões de prevalência e erros-padrão obtidos por uma ou outra técnica. O efeito do desenho maior que a unidade indicou que a amostragem complexa, em ambos os casos, aumentou da variância das estimativas. Cabe ao pesquisador a escolha da técnica e do estimador mais adequado ao seu objeto de estudo, permanecendo a escolha no âmbito epidemiológico.

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OBJETIVO: Investigar a prevalência de doença pulmonar referida entre idosos segundo características sociodemográficas, econômicas, estilo de vida, mobilidade física e condições de saúde. MÉTODOS: Trata-se de um estudo transversal, de base populacional, do qual participaram 1.957 idosos (60 anos ou mais). As informações foram coletadas por meio de entrevistas. Os participantes foram selecionados a partir de amostragem probabilística, estratificada, por conglomerados e obtida em dois estágios em seis municípios do Estado de São Paulo, no período de 2001 a 2002. Foram utilizadas estatísticas descritivas, testes de associação pelo chi2, razões de prevalência e intervalos de confiança de 95%. A análise ajustada foi conduzida por meio de regressão de Poisson. RESULTADOS: Dos entrevistados, cerca de 7% referiram doença pulmonar. Não houve associação entre doença pulmonar referida e vacinação contra influenza. A partir da análise ajustada foi possível identificar os seguintes fatores independentemente associados à referência da doença: tabagismo (RP=2,03; IC 95%: 1,39-2,97); uso de medicamentos (RP=2,05; IC 95%: 1,11-3,79); auto-avaliação do estado de saúde atual como ruim ou muito ruim (RP=1,89; IC 95%:1,20-2,96); e depressão, ansiedade ou problemas emocionais (RP=1,86; IC 95%: 1,11-3,10). CONCLUSÕES: Os achados do presente estudo reforçam a importância das doenças respiratórias em idosos, particularmente em grupos mais vulneráveis, justificando medidas preventivas e assistenciais específicas.

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Two-stage procedure for dental implants presents corroborated clinical success over 40 years. The evolution of surgical techniques, development of diagnostic methods, knowledge about tissue biology, and quality of implants regarding design and surface supported studies with I surgical stage followed by immediate prosthesis placement. However, several factors influence the treatment success with immediate loading. SO, this Study aimed to evaluate some factors regarding the success and characteristics of implants and patients.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)