A field model interpretation of crack initiation and growth behavior in ferroelectric ceramics: change of poling direction and boundary condition

Strain energy density expressions are obtained from a field model that can qualitatively exhibit how the electrical and mechanical disturbances would affect the crack growth behavior in ferroelectric ceramics. Simplification is achieved by considering only three material constants to account for elastic, piezoelectric and dielectric effects. Cross interaction of electric field (or displacement) with mechanical stress (or strain) is identified with the piezoelectric effect; it occurs only when the pole is aligned normal to the crack. Switching of the pole axis by 90degrees and 180degrees is examined for possible connection with domain switching. Opposing crack growth behavior can be obtained when the specification of mechanical stress sigma(infinity) and electric field E-infinity or (sigma(infinity), E-infinity) is replaced by strain e and electric displacement D-infinity or (epsilon(infinity), D-infinity). Mixed conditions (sigma(infinity),D-infinity) and (epsilon(infinity),E-infinity) are also considered. In general, crack growth is found to be larger when compared to that without the application of electric disturbances. This includes both the electric field and displacement. For the eight possible boundary conditions, crack growth retardation is identified only with (E-y(infinity),sigma(y)(infinity)) for negative E-y(infinity) and (D-y(infinity), epsilon(y)(infinity)) for positive D-y(infinity) while the mechanical conditions sigma(y)(infinity) or epsilon(y)infinity are not changed. Suitable combinations of the elastic, piezoelectric and dielectric material constants could also be made to suppress crack growth. (C) 2002 Published by Elsevier Science Ltd.

Prosocial norms and degree heterogeneity in social networks

We provide empirical evidence to support the claims that social diversity promotes prosocial behavior. We elicit a real-life social network and its members’ adherence to a social norm, namely inequity aversion. The data reveal a positive relationship between subjects’ prosociality and several measures of centrality. This result is in line with the theoretical literature that relates the evolution of social norms to the structure of social interactions and argues that central individuals are crucial for the emergence of prosocial behavior.

Role of G protein coupled inwardly rectifier K+ channels (GIRK) on the neurobiology depression

353 págs.

The strategic behavior of rational novices

There is a growing amount of experimental evidence that suggests people often deviate from the predictions of game theory. Some scholars attempt to explain the observations by introducing errors into behavioral models. However, most of these modifications are situation dependent and do not generalize. A new theory, called the rational novice model, is introduced as an attempt to provide a general theory that takes account of erroneous behavior. The rational novice model is based on two central principals. The first is that people systematically make inaccurate guesses when they are evaluating their options in a game-like situation. The second is that people treat their decisions similar to a portfolio problem. As a result, non optimal actions in a game theoretic sense may be included in the rational novice strategy profile with positive weights.

The rational novice model can be divided into two parts: the behavioral model and the equilibrium concept. In a theoretical chapter, the mathematics of the behavioral model and the equilibrium concept are introduced. The existence of the equilibrium is established. In addition, the Nash equilibrium is shown to be a special case of the rational novice equilibrium. In another chapter, the rational novice model is applied to a voluntary contribution game. Numerical methods were used to obtain the solution. The model is estimated with data obtained from the Palfrey and Prisbrey experimental study of the voluntary contribution game. It is found that the rational novice model explains the data better than the Nash model. Although a formal statistical test was not used, pseudo R^2 analysis indicates that the rational novice model is better than a Probit model similar to the one used in the Palfrey and Prisbrey study.

The rational novice model is also applied to a first price sealed bid auction. Again, computing techniques were used to obtain a numerical solution. The data obtained from the Chen and Plott study were used to estimate the model. The rational novice model outperforms the CRRAM, the primary Nash model studied in the Chen and Plott study. However, the rational novice model is not the best amongst all models. A sophisticated rule-of-thumb, called the SOPAM, offers the best explanation of the data.

Understanding Public Support for Externality-Correcting Taxes and Subsidies: A Lab Experiment

31 p.

Essays on Correlated Equilibrium and Voter Turnout

This thesis consists of three essays in the areas of political economy and game theory, unified by their focus on the effects of pre-play communication on equilibrium outcomes.

Communication is fundamental to elections. Chapter 2 extends canonical voter turnout models, where citizens, divided into two competing parties, choose between costly voting and abstaining, to include any form of communication, and characterizes the resulting set of Aumann's correlated equilibria. In contrast to previous research, high-turnout equilibria exist in large electorates and uncertain environments. This difference arises because communication can coordinate behavior in such a way that citizens find it incentive compatible to follow their correlated signals to vote more. The equilibria have expected turnout of at least twice the size of the minority for a wide range of positive voting costs.

In Chapter 3 I introduce a new equilibrium concept, called subcorrelated equilibrium, which fills the gap between Nash and correlated equilibrium, extending the latter to multiple mediators. Subcommunication equilibrium similarly extends communication equilibrium for incomplete information games. I explore the properties of these solutions and establish an equivalence between a subset of subcommunication equilibria and Myerson's quasi-principals' equilibria. I characterize an upper bound on expected turnout supported by subcorrelated equilibrium in the turnout game.

Chapter 4, co-authored with Thomas Palfrey, reports a new study of the effect of communication on voter turnout using a laboratory experiment. Before voting occurs, subjects may engage in various kinds of pre-play communication through computers. We study three communication treatments: No Communication, a control; Public Communication, where voters exchange public messages with all other voters, and Party Communication, where messages are exchanged only within one's own party. Our results point to a strong interaction effect between the form of communication and the voting cost. With a low voting cost, party communication increases turnout, while public communication decreases turnout. The data are consistent with correlated equilibrium play. With a high voting cost, public communication increases turnout. With communication, we find essentially no support for the standard Nash equilibrium turnout predictions.

Reggeization of some unequal mass processes involving higher spins : the reactions pion-nucleon going to (V,Nucleon), pion-nucleon going to (V,delta-hyperon), and photon-proton going to (positive pion,neutron)

Recent theoretical developments in the reggeization of inelastic processes involving particles with high spin are incorporated into a model of vector meson production. A number of features of experimental differential cross sections and density matrices are interpreted in terms of this model.

The method chosen for reggeization of helicity amplitudes first separates kinematic zeros and singularities from the parity-conserving amplitudes and then applies results of Freedman and Wang on daughter trajectories to the remaining factors. Kinematic constraints on helicity amplitudes at t = 0 and t = (M – M_Δ)² are also considered.

It is found that data for reactions of types πN→VN and πN→VΔ are consistent with a model of this type in which all kinematic constraints at t = 0 are satisfied by evasion (vanishing of residue functions). As a quantitative test of the parametrization, experimental differential cross sections of vector meson production reactions dominated by pion trajectory exchange are compared with the theory. It is found that reduced residue functions are approximately constant, once the kinematic behavior near t = (M – M_Δ)² has been removed.

The alternative possibility of conspiracy between amplitudes is also discussed; and it is shown that unless conspiracy is present, some amplitudes allowed by angular momentum conservation will not contribute with full strength in the forward direction. An example, γp→π⁺n in which the data for dσ/dt indicate conspiracy, is studied in detail.

Socioeconomic status, parental support, motivation and self-confidence in youth competitive sport

World Conference on Psychology and Sociology 2012

Reverberações da Lei n 8.213/91 à luz das concepções de deficiência: estudo de caso sobre o programa de sensibilização gerencial em uma organização privada de ensino profissionalizante

Com base nos rebatimentos da Lei n 8.213/1991, que prevê a obrigatoriedade legal de empresas privadas brasileiras contratarem de 2% a 5% de beneficiários da Previdência Social reabilitados ou de pessoas com deficiência (PcDs) habilitadas em seus quadros funcionais, o objetivo da presente pesquisa foi avaliar as repercussões da Lei de Cotas, tendo como referência as concepções de deficiência preponderantes dentro de uma organização privada de ensino profissionalizante por meio do seu Projeto de Sensibilização Gerencial. O projeto de sensibilização gerencial objetivou consolidar as etapas iniciais, na implementação de um programa institucional de valorização da diversidade. A hipótese principal formulada para a pesquisa, dentre outras relativas às concepções de deficiência, por parte de gestores, é que as reverberações positivas produzidas pela Lei de Cotas atingem, inclusive, as organizações empresariais supostamente distanciadas do movimento inclusionista. Para fins de avaliação das concepções de deficiência foram utilizados delineamentos de pesquisa estatística, compreendendo o teste de Shapiro-Wilk para determinar se as respostas às perguntas configuravam ou não uma distribuição normal, além do Coeficiente de Correlação de Pearson para medir a intensidade da relação linear entre as variáveis estudadas. Serviram como instrumentos da pesquisa um questionário sociodemográfico e um inventário de concepções de deficiência (ICD), sendo este direcionado para o objeto atitudinal, considerando-se as percepções sociais favoráveis e desfavoráveis no grupo pesquisado. Esse inventário de concepções de deficiência é composto de sete blocos de asserções e de uma escala do tipo Likert de seis pontos, que foi aplicada em um universo que contempla estrategicamente 60 participantes selecionados em três (3) grupos (Grupo piloto 1 envolvendo 30 participantes das áreas do Comitê Gestor do projeto na empresa; Grupo piloto 2 envolvendo 12 trainees; e Grupo Gerencial envolvendo 18 participantes, incluindo Gerentes de Área e Gerentes de Equipe da Superintendência de Produtos Educacionais). De posse dos resultados da avaliação das concepções de deficiência pelo ICD, foram realizados workshops de sensibilização com os participantes com o objetivo de sensibilizá-los e disseminar o conhecimento sobre inclusão social e laboral de PcDs, as ações de políticas públicas na atualidade, a natureza das deficiências, considerando-se os aspectos sociais da profissionalização, empregabilidade de pessoas com deficiência na empresa. Para tanto, foram empregadas técnicas e procedimentos lúdicos, além de debates para fins de reflexão crítica por parte dos participantes. A avaliação de reação foi conduzida ao término desses workshops. O conjunto dos dados levantados até então possibilitou proceder-se a um diagnóstico das concepções que prevalecem sobre PcDs na organização alvo da pesquisa. Os resultados evidenciaram a coexistência de concepções distintas da deficiência, indicando que, embora concepções negativas se perpetuem, as reverberações da Lei de Cotas têm apresentado também repercussões visivelmente positivas valorizando, assim, as ações corporativas apontadas para a diversidade humana, no contexto do trabalho. Em termos conclusivos, considera-se, no entanto, que o processo de inclusão laboral deva ser percebido por parte dos gestores como contínuo e em direção à mudança do comportamento humano nas organizações frente à profissionalização de PcDs. Posteriormente, tendo-se como suporte os resultados da presente pesquisa, um plano de ação institucional será implementado, como proposta de um programa balizado em 10 projetos sintéticos que servirão de modelo para empresas brasileiras interessadas em incluir a diversidade e reter talentos com deficiência em seus postos de trabalho, de modo a garantir-lhes o direito de exercício pleno da cidadania.

Reincidentes da Penitenciária de Benguela: prisão e história em Angola.

Este trabalho é resultado de uma pesquisa realizada com sujeitos jovens e adultos privados de liberdade, reincidentes, com pelo menos metade da pena cumprida na Penitenciária de Benguela/Angola. Teve como foco a compreensão do sentido atribuído por esses sujeitos à experiência de ser preso reincidente, percebendo como experienciam o programa de reeducação do sistema prisional local. Os fundamentos teóricos da investigação basearam-se em autores que discutem a realidade da prisão; o direito à educação de pessoas em espaços de privação de liberdade; e a situação histórica de Angola, marcada pela longa guerra civil, após a Independência que a livrou do colonialismo do governo português, por tantos anos. Autores angolanos contribuíram para o desvelamento dessa condição histórica, e vários brasileiros foram fundamentais para compreender a temática relativa à prisão. O tema tornou-se relevante entre pesquisadores na academia brasileira, provocados em grande parte por acordos internacionais sobre direitos humanos e, especialmente, sobre o direito à educação de pessoas jovens e adultas em espaços de privação de liberdade. O balizamento brasileiro e internacional serviu para avaliar como o Estado angolano se porta diante desse direito, e de que forma atende (ou não) o preceituado nas prisões angolanas, sendo signatário de acordos internacionais. A investigação pode ser considerada um estudo de caso qualitativo, cuja recolha de informações utilizou observação, entrevistas e questionários que geraram dados quantitativos. Estes resultaram de questionários aplicados a dez reeducadores dos serviços prisionais e a 26 reclusos reincidentes, entre os quais 23 do sexo masculino e três do sexo feminino, todos não identificados. As entrevistas realizadas se fizeram desde o diretor da instituição penal ao responsável provincial da reeducação; ouviram o responsável pela área de segurança do presídio, um advogado de presos e a mãe de um dos reclusos reincidentes. Problemas de ordem política, econômica, social, assim como o fator guerra que acompanhou toda a história de Angola (1975-2002) contribuíram, em grande parte, para que os sujeitos especialmente jovens cometessem delitos e sofressem a privação da liberdade. No dizer dos sujeitos, a expectativa de mudança de vida se põe na volta à escola e no aprendizado de uma profissão no que depositam esperanças de que a cadeia possa contribuir, para que a sociedade os discrimine menos, porque egressos do sistema penitenciário de Angola.

Sexual Behavior Modulates Contextual Fear Memory Through Dopamine D1/D5 Receptors

Traumatic events always lead to aversive emotional memory, i.e., fear memory. In contrast, positive events in daily life such as sex experiences seem to reduce aversive memory after aversive events. Thus, we hypothesized that post-traumatic pleasurable ex

Positive Correlations in Tunneling through coupled Quantum Dots

Due to the Fermi-Dirac statistics of electrons the temporal correlations of tunneling events in a double barrier setup are typically negative. Here, we investigate the shot noise behavior of a system of two capacitively coupled quantum dot states by means of a Master equation model. In an asymmetric setup positive correlations in the tunneling current can arise due to the bunching of tunneling events. The underlying mechanism will be discussed in detail in terms of the current-current correlation function and the frequency-dependent Fano factor.

Numerical modeling of deep soil mixing excavation support

The finite element method (FEM) is growing in popularity over the pressure diagram/hand calculation method for analysis of excavation systems in general and deep soil mixing excavations in particular. In this paper, a finite element analysis is used to study the behavior of a deep mixed excavation. Through the use of Plaxis (a FEM software program), the construction sequence is simulated by following the various construction phases allowing for deflections due to strut or anchor installation to be predicted. The numerical model used in this study simulates the soil cement columns as a continuous wall matching the bending stiffness of the actual wall. Input parameters based on laboratory tests and modeling assumptions are discussed. An example of the approach is illustrated using the Islais Creek Transport/Storage Project in San Francisco, California. Copyright ASCE 2006.

Au@Si-n: Growth behavior, stability and electronic structure

The configurations, stability, and electronic structure of AuSin (n = 1-16) clusters have been investigated within the framework of the density functional theory at the B3PW91/LanL2DZ and PW91/DNP levels. The results show that the Au atom begins to occupy the interior site for cages as small as Si-11 and for Si-12 the Au atom completely falls into the interior site forming Au@Si-12 cage. A relatively large embedding energy and small HOMO-LUMO gap are also found for this Au@Si-12 structure indicating enhanced chemical activity and good electronic transfer properties. All these make Au@Si-12 attractive for cluster-assembled materials.

Narrowing of band gap and low-temperature spin glass behavior of FeNi co-doped ZnO nanowires

This letter reports on the Raman, optical and magnetic properties of FeNi co-doped ZnO nanowires prepared via a soft chemical solution method. The microstructural investigations show that the NiFe co-dopants are substituted into wurtzite ZnO nanostructure without forming any secondary phase. The co-doped nanowires show a remarkable reduction of 34 nm (267.9 meV) in the optical band gap, while suppression in the deep-level defect transition in visible luminescence. Furthermore, these nanowires exhibit ferromagnetism and an interesting low-temperature spin glass behavior, which may arise due to the presence of disorder and strong interactions of frustrated spin moments of Ni and Fe co-dopants on the ZnO lattice sites. Copyright (C) EPLA, 2009