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My research has focused on the precipitation of iron minerals, mostly oxides and hydroxides, in aqueous systems across steep pH and Eh gradients. Unlike most work in this area, which involves loose precipitates filtered out of solutions, I have focused on precipitated aggregates and, more specifically, on those that are self-organized into dis-crete structures or patterns. This topic is actually quite narrow because such types of natu-ral material organization are rare within the geochemical realm compared with the mor-phological richness of crystals, not to mention the phantasmagoria of life.My investigation of iron-based examples has included three types of physical sys-tems: 1) growth of tubular structures around bubbles coming off a charged cathode in a free solution where convection dominates; 2) development of Liesegang patterns within gelled solutions due to reactions dominated by diffusion; and 3) formation of a cement-ing matrix within the aqueous interface between particles of silica. The third case in-volves physical characteristics of the first two in that it is primarily a tightly packed, dif-fusion-limited process, but at least initially the generation of gases can create mechani-cally driven flows through the interstitial spaces.All three systems and studies are inextricably related for both tubular ('vermi-form') structures and Liesegang patterns are commonly found in natural iron-cemented sediments such as massive laterite, ironstone deposits, and banded iron formations. They are also found on a much smaller scale within discrete 'concretions' and represent the two poles of the gradient between convection-based and diffusion-based systems. As Seilacher (2001) states concerning concretions, "the distribution and precipitation of dis-solved constituents, such iron and manganese, proceeds in two radically different mor-phospaces, which are typified by dendrites [and I would include tubes and other linear growth] on the one hand and Liesegang rings on the other." Both have been observed in my lab creations with surprising frequency and tenacity even in systems thought to be in-hibitory.

Deep learning techniques have achieved profound success in many challenging real-world applications, including image recognition, speech recognition, and machine translation. This success has increased the demand for developing deep neural networks and more effective learning approaches. The aim of this thesis is to consider the problem of learning a neural network classifier and to propose a novel approach to solve this problem under the Information Bottleneck (IB) principle. Based on the IB principle, we associate with the classification problem a representation learning problem, which we call ``IB learning". A careful investigation shows there is an unconventional quantization problem that is closely related to IB learning. We formulate this problem and call it ``IB quantization". We show that IB learning is, in fact, equivalent to the IB quantization problem. The classical results in rate-distortion theory then suggest that IB learning can benefit from a vector quantization approach, namely, simultaneously learning the representations of multiple input objects. Such an approach assisted with some variational techniques, result in a novel learning framework that we call ``Aggregated Learning (AgrLearn)", for classification with neural network models. In this framework, several objects are jointly classified by a single neural network. In other words, AgrLearn can simultaneously optimize against multiple data samples which is different from standard neural networks. In this learning framework, two classes are introduced, ``deterministic AgrLearn (dAgrLearn)" and ``probabilistic AgrLearn (pAgrLearn)". We verify the effectiveness of this framework through extensive experiments on standard image recognition tasks. We show the performance of this framework over a real world natural language processing (NLP) task, sentiment analysis. We also compare the effectiveness of this framework with other available frameworks for the IB learning problem.

This work expanded on previous research on school effectiveness by developing and testing hypotheses about the specific relationships between school characteristics---including aggregated student and classroom characteristics---and student academic performance. The work used data from the "Early Childhood Transitions Project," a study of intensive social and educational services in a suburban school system, to identify and test the effect of a limited set of school-level characteristics on test score gains made by individual students on the Metropolitan Achievement Test (MAT) between the second and third grade. The analyses found that there are differences in the size of schools, the percent of low performing students, and the percent of students who are non-English speaking across the schools in the sample. Test score gains are affected by concentrations of these types of students at the schools. Students at schools in this sample with high concentrations of non-English speaking students or high concentrations of Hispanic students achieve lower test score gains than students in other schools. Another "concentration effect" emerged from the analysis of high-performing students in the sample. In particular, female students with high scores on the second grade MAT who are in schools with large concentrations of students who perform poorly on the second grade exam have smaller third grade test score gains than similar students who are in schools without a concentration of low performing students. These results suggest that more attention be paid to the influence that the characteristics of the student population have on the school's ability to implement the curriculum. As a first step, researchers may want to simply document the differences in the educational characteristics of students entering schools. This would provide evidence of the segregation that occurs across schools. Researchers may then want to conceptualize students within schools in terms of their homogeneity on demographic measures and their homogeneity on educational characteristics. This "educational minority or majority" concept may bring researchers closer to understanding the school environment, as it is organized by schools and experienced by children. / Ph. D.

This paper examines in a descriptive manner how two groups of variables, institutional and socio-economic, correlate with voter turnout respectively and if their magnitude have changed over time in OECD countries. Previous research is often based on data from the 70’s and 80’s. Since then, voter turnout in democratic countries has decreased and more citizens do not use their fundamental democratic right of being involved in the process of choosing their representatives. To answer the paper hypotheses i.e. analyzing what factors that correlates with voter turnout, panel data between 1980 and 2012 are used which is estimated by an OLS approach. The outcome of the empirical estimations indicates that 13 out of 19 variables have a significant relationship with turnout. Most of the variables magnitudes are a bit lower than previous literature. From the time sensitivity analysis the result indicates that voters are less influenced by the significant variables that focus on the voting cost. It seems that voters in the 21st century meet voting costs in different manner than previously.

We present a method aimed at estimating global bilateral migration flows and assessing their determinants. We employ that fact that available net migration figures for a country are (nonlinear) aggregates of migration flows from and to all other countries of the world in order to construct a statistical model that links the determinants of (unobserved) migration ows to total net migration. Using simple specifications based on the gravity model for international migration, we find that migration flows can be explained by standard gravity model variables such as GDP differences, distance or bilateral population. The usefulness of such models is exemplified by combining estimated specifications with population and GDP projections in order to assess quantitatively the expected changes in migration flows to Europe in the coming decades. / Series: WWWforEurope

O trânsito das metrópoles do novo milênio é um dos problemas que mais leva ao desperdício de recursos, com a consequente redução da qualidade de vida nas metrópoles. Os gastos ligados a vários fatores fazem com que o uso do veículo na hora do pico de trânsito seja duas vezes maior que o normal. O trânsito também gera poluição e consequentemente contribui para doenças pulmonares. O problema de planejamento operacional das infraestruturas viárias em uma grande metrópole constitui algo muito complexo. Problemas deste tamanho ainda não podem ser enfrentados, pelos sistemas computacionais modernos, na sua totalidade. Este problema se resolve dividindo as metrópoles em áreas nas quais é possível conduzir estudos que resolvam as situações locais. A circulação entre zonas distantes das metrópoles é suportada pelas vias expressas, as quais podem ser otimizadas globalmente. Com o crescimento das metrópoles e de seu número de veículos, muitas vezes, as infraestruturas ficam inadequadas, fazendo com que parte dos fluxos das vias expressas invadam os bairros. Neste trabalho se propõe fortalecer a capacidade dos bairros de enfrentar as situações de fluxos intensos. O processo proposto é hierárquico tendo uma primeira fase composta de estudos locais efetuados com simulação micro/mesoscópica, e uma sucessiva otimização global baseada nos resultados das locais. O sistema de otimização necessita de um teste que avalia as soluções escolhidas ao longo do processo. Na literatura da engenharia de tráfego se encontram diferentes níveis de análise do trânsito que geram as três categorias de modelos de simulação. Estas categorias ganham os nomes de modelos microscópicos, mesoscópicos e macroscópicos, mas nenhuma se mostra apta a ser utilizada como teste do sistema proposto. Neste trabalho se propõe um simulador que abstrai o conceito de rede viária reduzindo os custos computacionais até conseguir simular uma inteira metrópole. A técnica de estudo proposta, nos testes, se revela útil em determinadas situações, mas ainda deve ser confrontada com as novas tecnologias capazes de refinar os planos operacionais em tempo real na base dos dados de sensores e câmeras espalhados nas infraestruturas. / The traffic of new-millennium metropolises is one of the problems that most cause resources waste, consequently reducing the quality of life in these metropolises. The costs related to a series of causes make the use of vehicles at rush times be twice as frequent as during other times. The traffic also generates pollution, hence contributing to pulmonary diseases. The infrastructures operational planning problems in big cities is a complex issue. Such big problems still cannot be fully faced by modern computer systems. This can be solved dividing the cities into areas where it is possible to run studies to solve local situations. The circulation between distant areas in metropolises can be done via express motorways, which can be globally improved. With the expansion of big cities and their vehicles, the infrastructures frequently become inadequate and the stream invades neighborhoods. The aim of the present work is to improve the capacity of neighborhoods streams, offering besides technical norms, a global optimization based on local results. The optimization system needs a test that evaluates the chosen solutions along the process. In traffic engineering literature, there are different levels of traffic analysis that generate the three simulation model categories. These categories are named microscopic, mesoscopic, and macroscopic models, but none of them is able to be used as test to the proposed system. In this work, it is proposed a simulator that abstracts the concept of road network, reducing the computer expenses up to the simulation of a whole city. The study technic pruioposed in the tests shows itself as useful in certain situations, but still must be confronted with new technologies able to refine the operational plans in real time based on the sensors and cameras data.

O trânsito das metrópoles do novo milênio é um dos problemas que mais leva ao desperdício de recursos, com a consequente redução da qualidade de vida nas metrópoles. Os gastos ligados a vários fatores fazem com que o uso do veículo na hora do pico de trânsito seja duas vezes maior que o normal. O trânsito também gera poluição e consequentemente contribui para doenças pulmonares. O problema de planejamento operacional das infraestruturas viárias em uma grande metrópole constitui algo muito complexo. Problemas deste tamanho ainda não podem ser enfrentados, pelos sistemas computacionais modernos, na sua totalidade. Este problema se resolve dividindo as metrópoles em áreas nas quais é possível conduzir estudos que resolvam as situações locais. A circulação entre zonas distantes das metrópoles é suportada pelas vias expressas, as quais podem ser otimizadas globalmente. Com o crescimento das metrópoles e de seu número de veículos, muitas vezes, as infraestruturas ficam inadequadas, fazendo com que parte dos fluxos das vias expressas invadam os bairros. Neste trabalho se propõe fortalecer a capacidade dos bairros de enfrentar as situações de fluxos intensos. O processo proposto é hierárquico tendo uma primeira fase composta de estudos locais efetuados com simulação micro/mesoscópica, e uma sucessiva otimização global baseada nos resultados das locais. O sistema de otimização necessita de um teste que avalia as soluções escolhidas ao longo do processo. Na literatura da engenharia de tráfego se encontram diferentes níveis de análise do trânsito que geram as três categorias de modelos de simulação. Estas categorias ganham os nomes de modelos microscópicos, mesoscópicos e macroscópicos, mas nenhuma se mostra apta a ser utilizada como teste do sistema proposto. Neste trabalho se propõe um simulador que abstrai o conceito de rede viária reduzindo os custos computacionais até conseguir simular uma inteira metrópole. A técnica de estudo proposta, nos testes, se revela útil em determinadas situações, mas ainda deve ser confrontada com as novas tecnologias capazes de refinar os planos operacionais em tempo real na base dos dados de sensores e câmeras espalhados nas infraestruturas. / The traffic of new-millennium metropolises is one of the problems that most cause resources waste, consequently reducing the quality of life in these metropolises. The costs related to a series of causes make the use of vehicles at rush times be twice as frequent as during other times. The traffic also generates pollution, hence contributing to pulmonary diseases. The infrastructures operational planning problems in big cities is a complex issue. Such big problems still cannot be fully faced by modern computer systems. This can be solved dividing the cities into areas where it is possible to run studies to solve local situations. The circulation between distant areas in metropolises can be done via express motorways, which can be globally improved. With the expansion of big cities and their vehicles, the infrastructures frequently become inadequate and the stream invades neighborhoods. The aim of the present work is to improve the capacity of neighborhoods streams, offering besides technical norms, a global optimization based on local results. The optimization system needs a test that evaluates the chosen solutions along the process. In traffic engineering literature, there are different levels of traffic analysis that generate the three simulation model categories. These categories are named microscopic, mesoscopic, and macroscopic models, but none of them is able to be used as test to the proposed system. In this work, it is proposed a simulator that abstracts the concept of road network, reducing the computer expenses up to the simulation of a whole city. The study technic pruioposed in the tests shows itself as useful in certain situations, but still must be confronted with new technologies able to refine the operational plans in real time based on the sensors and cameras data.

Prostaglandins, released from Kupffer cells, have been shown to mediate the increase in hepatic glycogenolysis by various stimuli such as zymosan, endotoxin, immune complexes, and anaphylotoxin C3a involving prostaglandin (PG) receptors coupled to phospholipase C via a G(0) protein. PGs also decreased glucagon-stimulated glycogenolysis in hepatocytes by a different signal chain involving PGE(2) receptors coupled to adenylate cyclase via a G(i) protein (EP(3) receptors). The source of the prostaglandins for this latter glucagon-antagonistic action is so far unknown. This study provides evidence that Kupffer cells may be one source: in Kupffer cells, maintained in primary culture for 72 hours, glucagon (0.1 to 10 nmol/ L) increased PGE(2), PGF(2 alpha), and PGD(2) synthesis rapidly and transiently. Maximal prostaglandin concentrations were reached after 5 minutes. Glucagon (1 nmol/L) elevated the cyclic adenosine monophosphate (cAMP) and inositol triphosphate (InsP(3)) levels in Kupffer cells about fivefold and twofold, respectively. The increase in glyco gen phosphorylase activity elicited by 1 nmol/L glucagon was about twice as large in monocultures of hepatocytes than in cocultures of hepatocytes and Kupffer cells with the same hepatocyte density. Treatment of cocultures with 500 mu mol/L acetylsalicylic acid (ASA) to irreversibly inhibit cyclooxygenase (PGH-synthase) 30 minutes before addition of glucagon abolished this difference. These data support the hypothesis that PGs produced by Kupffer cells in response to glucagon might participate in a feedback loop inhibiting glucagon-stimulated glycogenolysis in hepatocytes.