Approach to Equilibrium for a Class of Random Quantum Models of Infinite Range

We consider random generalizations of a quantum model of infinite range introduced by Emch and Radin. The generalizations allow a neat extension from the class l (1) of absolutely summable lattice potentials to the optimal class l (2) of square summable potentials first considered by Khanin and Sinai and generalised by van Enter and van Hemmen. The approach to equilibrium in the case of a Gaussian distribution is proved to be faster than for a Bernoulli distribution for both short-range and long-range lattice potentials. While exponential decay to equilibrium is excluded in the nonrandom l (1) case, it is proved to occur for both short and long range potentials for Gaussian distributions, and for potentials of class l (2) in the Bernoulli case. Open problems are discussed.

Recognising and monitoring high-level behaviours in complex spatial environments

The recognition of activities from sensory data is important in advanced surveillance systems to enable prediction of high-level goals and intentions of the target under surveillance. The problem is complicated by sensory noise and complex activity spanning large spatial and temporal extents. This paper presents a system for recognising high-level human activities from multi-camera video data in complex spatial environments. The Abstract Hidden Markov mEmory Model (AHMEM) is used to deal with noise and scalability The AHMEM is an extension of the Abstract Hidden Markov Model (AHMM) that allows us to represent a richer class of both state-dependent and context-free behaviours. The model also supports integration with low-level sensory models and efficient probabilistic inference. We present experimental results showing the ability of the system to perform real-time monitoring and recognition of complex behaviours of people from observing their trajectories within a real, complex indoor environment.

Education, preferences for leisure, and the optimal income tax schedule

Recent advances in dynamic Mirrlees economies have incorporated the treatment of human capital investments as an important dimension of government policy. This paper adds to this literature by considering a two period economy where agents are di erentiated by their preferences for leisure and their productivity, both private information. The fact that productivity is only learnt later in an agent's life introduces uncertainty to agent's savings and human capital choices and makes optimal the use of multi-period tie-ins in the mechanism that characterizes the government policy. We show that optimal policies are often interim ine cient and that the introduction of these ine ciencies may take the form of marginal tax rates on labor income of varying sign and educational policies that include the discouragement of human capital acquisition. With regards to implementation, state-dependent linear taxes implement optimal savings, while human capital policies may require labor income taxes that depend directly on agents' schooling.

Ensaios sobre o fator estocástico de descontos

Este trabalho propõe maneiras alternativas para a estimação consistente de uma medida abstrata, crucial para o estudo de decisões intertemporais, o qual é central a grande parte dos estudos em macroeconomia e finanças: o Fator Estocástico de Descontos (SDF, sigla em Inglês). Pelo emprego da Equação de Apreçamento constrói-se um inédito estimador consistente do SDF que depende do fato de que seu logaritmo é comum a todos os ativos de uma economia. O estimador resultante é muito simples de se calcular, não depende de fortes hipóteses econômicas, é adequado ao teste de diversas especificações de preferência e para a investigação de paradoxos de substituição intertemporal, e pode ser usado como base para a construção de um estimador para a taxa livre de risco. Alternativas para a estratégia de identificação são aplicadas e um paralelo entre elas e estratégias de outras metodologias é traçado. Adicionando estrutura ao ambiente inicial, são apresentadas duas situações onde a distribuição assintótica pode ser derivada. Finalmente, as metodologias propostas são aplicadas a conjuntos de dados dos EUA e do Brasil. Especificações de preferência usualmente empregadas na literatura, bem como uma classe de preferências dependentes do estado, são testadas. Os resultados são particularmente interessantes para a economia americana. A aplicação de teste formais não rejeita especificações de preferências comuns na literatura e estimativas para o coeficiente relativo de aversão ao risco se encontram entre 1 e 2, e são estatisticamente indistinguíveis de 1. Adicionalmente, para a classe de preferência s dependentes do estado, trajetórias altamente dinâmicas são estimadas para a tal coeficiente, as trajetórias são confinadas ao intervalo [1,15, 2,05] e se rejeita a hipótese de uma trajetória constante.

The macroeconomic effects of infrequent information with adjustment costs

We extend the macroeconomic literature on Sstype rules by introducing infrequent information in a kinked ad justment cost model. We first show that optimal individual decision rules are both state-and -time dependent. We then develop an aggregation framework to study the macroeconomic implications of such optimal individual decision rules. In our model, a vast number of agents act together, and more so when uncertainty is large.The average effect of an aggregate shock is inversely related to its size and to aggregate uncertainty. These results are in contrast with those obtained with full information ad justment cost models.

Securitização de recebíveis da agroenergia: um estudo de caso baseado em títulos do agronegócio

Desde o final da década de 90, a securitização de ativos vem se firmando no mercado brasileiro como uma importante alternativa de captação de recursos. Essa inovação financeira permite às empresa o acesso direto ao mercado de capitais, para a venda de títulos lastreados em suas carteiras de recebíveis, eliminando a intermediação bancária e permitindo reduções no custo de capital, inclusive em comparação com títulos convencionais de dívida corporativa. Os títulos de securitização são em regra emitidos por um veículo de propósito específico (FIDC ou companhia securitizadora), com o objetivo de segregar os riscos do originador/tomador em relação aos créditos securitizados (lastro da emissão). Em 2004, a Lei 11.076 criou os novos títulos do agronegócio (CDA-WA, CDCA, LCA e CRA), inspirada na legislação da securitização imobiliária (SFI - Lei 9.514/97), buscando disponibilizar ao agronegócio uma nova fonte de recursos, via emissão de títulos no mercado de capitais. Desde então, um número crescente de operações estruturadas com esses papéis pôde ser observada, demonstrando sua funcionalidade e potencial. No entanto, o volume de captações públicas mais sofisticadas fundadas na emissão de cotas de FIDCs e de CRAs ainda se apresenta muito reduzida em relação à demanda do agronegócio por financiamento, sobretudo levando-se em conta a representatividade desse setor no Brasil. O setor sucro-energético é provavelmente o segmento do agronegócio que está em melhor posição para o desenvolvimento de operações de securitização, por apresentar características como: escala, padronização dos produtos, grau de consolidação dos grupos empresariais e perspectivas de crescimento, além do forte apelo ambiental. Os papéis associados a esse segmento possuem, dessa forma, um potencial singular para superar a resistência natural de investidores às aplicações financeiras na área agrícola. Este trabalho dedica-se a investigar como o conceito de securitização pode ser aplicado em operações ligadas ao agronegócio, particularmente ao setor sucro-alcooleiro. A partir de um estudo de caso, serão analisados aspectos operacionais de uma emissão pública de CRAs, ressaltando os mecanismos e procedimentos adotados para lidar com as particularidades dos títulos oriundos do agronegócio. O estudo mostra que a estruturação desse tipo de operação apresenta algumas características e desafios diferentes das operações fundadas em outros papéis, porém a priori administráveis a partir das técnicas tradicionais de securitização e da incorporação de mecanismos suplementares de gestão de riscos.

Demand-pull stagflation

This paper explores the possibility of stagflation emanating exc1usively from monetaJy sbocks, without concurrent supply shocks or shifts in potential output. This arises in connection with a tight money paradox. in the context of a fiscal theory of the price leveI. The paper exhibits perfect foresight equilibria with output and inflation fluctuating in opposite direetions as a consequence of small monetary shocks, and also following changes in monetaJy policy regime that launch the economy into hyperinflation or that produce dramatic stabilization of already high inflation. For that purpose, an analytically convenient dynamic general equilibrium macro model is deve10ped wbere nominal rigidities are represented by a cross between staggered two-period contracts and state dependent price adjustment in the presence of menu costs.

Does liquidity constraints matter for Ricardian equivalence?

The paper analysis a general equilibrium model with two periods, several households and a government that has to finance some expenditures in the first period. Households may have some private information either about their type (adverse selection) or about some action levei chosen in the first period that affects the probability of certain states of nature in the second period (moral hazard). Trade of financiai assets are intermediated by a finite collection of banks. Banks objective functions are determined in equilibrium by shareholders. Due to private information it may be optimal for the banks to introduce constraints in the set of available portfolios for each household as wellas household specific asset prices. In particular, households may face distinct interest rates for holding the risk-free asset. The government finances its expenditures either by taxing households in the first period or by issuing bonds in the first period and taxing households in the second period. Taxes may be state-dependent. Suppose government policies are neutml: i) government policies do not affect the distribution of wealth across households; and ii) if the government decides to tax a household in the second period there is a portfolio available for the banks that generates the Mme payoff in each state of nature as the household taxes. Tben, Ricardian equivalence holds if and only if an appropriate boundary condition is satisfied. Moreover, at every free-entry equilibrium the boundary condition is satisfied and thus Ricardian equivalence holds. These results do not require any particular assumption on the banks' objective function. In particular, we do not assume banks to be risk neutral.

O ajuste fiscal nos estados 1998-2007

O presente projeto de pesquisa analisa o ajuste fiscal nos estados nos últimos dez anos. Existe um amplo consenso de que esse grande avanço fiscal ocorreu principalmente em decorrência Lei nº 9.496/97, que vinculou a renegociação das dívidas estaduais com a implementação de um amplo programa de saneamento financeiro, assim como, pela promulgação da Lei de Responsabilidade Fiscal (LRF). O estudo mostra que , como regra geral, o padrão de ajuste fiscal implementado na maioria dos estados foi marcado principalmente, por um forte aumento das receitas tributárias. A contribuição do controle das despesas foi bastante limitada o que resultou em um padrão de ajuste fiscal de má qualidade, já a obtenção de crescentes superávits primários resultaram essencialmente do aumento da carga tributária.

Environmental regulation, technology adoption and structural transformation: evidence from Brazilian sugarcane industry

We estimate the effects of the adoption of mechanized agriculture led by a new environmental regulation on structural change of local labor markets within a large emerging country, Brazil. In 2002, the state of S\~{a}o Paulo passed a law outlying the timeline to end sugarcane pre-harvest burning in the state. The environmental law led to the fast adoption of mechanized harvest. We investigate if the labor intensity of sugarcane production decreases; and, if so, if it leads to structural changes in the labor market. We use satellite data containing the type of sugarcane harvesting -- manual or mechanic harvest -- paired with official labor market data.%, also geomorphometric data base for our instrumental variable correction. We find suggestive evidence that mechanization of the field led to an increase in utilization of formal workers and a reduction in formal labor intensity in the sugarcane sector. This is partially compensated by an increase in the share of workers in other agricultural crops and in the construction and services sector. Although we find a reduction in employment in the manufacturing sector, the demand generated by the new agro-industries affected positively the all sectors via an increase in workers' wage.

Selective Coupling between Theta Phase and Neocortical Fast Gamma Oscillations during REM-Sleep in Mice

TORT, A. B. L. ; SCHEFFER-TEIXEIRA, R ; Souza, B.C. ; DRAGUHN, A. ; BRANKACK, J. . Theta-associated high-frequency oscillations (110-160 Hz) in the hippocampus and neocortex. Progress in Neurobiology , v. 100, p. 1-14, 2013.

Hermenêutica constitucional e fficácia dos Direitos Sociais

The present research has, as general objective, to seek a constitucional hermeneutics directed toward the improvement of the efficacy of the social rights rules, with the purpose to solve the elapsins problems from the general picture of its inefficiency, which are disposed on the Constitution, in its ample majority, as mere regular norms. Leaving of the premise that no Constitutional norm can be without being materialized and the true development of the State is it the social one (based on the principles of freedom, equality and solidarity), it will be demonstrated that the arguments in favor of the legislative inefficiency configure a true blow on the Democratic State of Brazilian Law. For this, it will be done, preliminarily, a study of the basic rights, legal category where it is found the social rights. To follow, it will be analyzed the hermeneutics of the legal norms, with emphasis on the specifics of the constitutional hermeneutics and its methods of interpretation. Finally, the aspect on the improvement of efficacy and the effectiveness of the social rights will be studied, through a new readind of certain dogmas that still persist in the legal world, being distinguished the institutiones of the reserve of the possible and the existential minimum. Ahead of this, after verifying the new paradigmas of the interpretable activity, will be demonstrated how it is possible to get an upgrade on the effectiveness of the social rights

Controle preditivo robusto baseado em desigualdades matriciais lineares aplicado a um sistema de tanques acoplados

This work deals with an on-line control strategy based on Robust Model Predictive Control (RMPC) technique applied in a real coupled tanks system. This process consists of two coupled tanks and a pump to feed the liquid to the system. The control objective (regulator problem) is to keep the tanks levels in the considered operation point even in the presence of disturbance. The RMPC is a technique that allows explicit incorporation of the plant uncertainty in the problem formulation. The goal is to design, at each time step, a state-feedback control law that minimizes a 'worst-case' infinite horizon objective function, subject to constraint in the control. The existence of a feedback control law satisfying the input constraints is reduced to a convex optimization over linear matrix inequalities (LMIs) problem. It is shown in this work that for the plant uncertainty described by the polytope, the feasible receding horizon state feedback control design is robustly stabilizing. The software implementation of the RMPC is made using Scilab, and its communication with Coupled Tanks Systems is done through the OLE for Process Control (OPC) industrial protocol

Effects of inhibition gastric acid secretion on arterial acid-base status during digestion in the toad Bufo marinus

Digestion affects acid-base status, because the net transfer of HCl from the blood to the stomach lumen leads to an increase in HCO3- levels in both extra- and intracellular compartments. The increase in plasma [HCO3-], the alkaline tide, is particularly pronounced in amphibians and reptiles, but is not associated with an increased arterial pH, because of a concomitant rise in arterial Pco(2) caused by a relative hypoventilation. In this study, we investigate whether the postprandial increase in Paco(2) of the toad Bufo marinus represents a compensatory response to the increased plasma [HCO3-] or a state-dependent change in the control of pulmonary ventilation. To this end, we successfully prevented the alkaline tide, by inhibiting gastric acid secretion with omeprazole, and compared the response to that of untreated toads determined in our laboratory during the same period. In addition, we used vascular infusions of bicarbonate to mimic the alkaline tide in fasting animals. Omeprazole did not affect blood gases, acid-base and haematological parameters in fasting toads, but abolished the postprandial increase in plasma [HCO3-] and the rise in arterial Pco(2) that normally peaks 48 h into the digestive period. Vascular infusion of HCO3-, that mimicked the postprandial rise in plasma [HCO3-], led to a progressive respiratory compensation of arterial pH through increased arterial Pco(2) Thus, irrespective of whether the metabolic alkalosis is caused by gastric acid secretion in response to a meal or experimental infusion of bicarbonate, arterial pH is being maintained by an increased arterial Pco(2). It seems, therefore, that the elevated Pco(2), occuring during the postprandial period, constitutes of a regulated response to maintain pH rather than a state-dependent change in ventilatory control. (C) 2003 Elsevier B.V. All rights reserved.