O controle biológico de pragas agrícolas é um dos serviços ecossistêmicos mais valorizados, dada sua importância para a produção agrícola. Embora vários estudos tenham demonstrado que a abundância e riqueza de predadores aumentam com a quantidade de floresta nativa, os mecanismos subjacentes que modulam a relação entre a cobertura florestal e provisão de controle biológico em diferentes escalas espaciais são ainda pouco conhecidos. Neste trabalho, utilizamos experimentos de exclusão de vertebrados voadores em oito paisagens cafeeiras na Mata Atlântica, num gradiente de cobertura florestal, e quantificamos as consequências para a perda foliar e para a frutificação. A perda foliar mostrou uma relação negativa com a cobertura florestal em paisagens com 2 km de raio, indicando que a herbivoria é melhor controlada em paisagens com alta cobertura florestal, especialmente na presença de aves e morcegos. No entanto, no nível local, 300 m ao redor das plantas de café, a perda foliar e a frutificação responderam diferentemente à cobertura florestal. Em unidades com baixa cobertura florestal local, a exclusão de aves e morcegos aumentou a perda foliar e diminuiu a frutificação em uma média de 13%. Por outro lado, em unidades com alta cobertura florestal local, a exclusão de aves e morcegos não teve efeitos significativos nem na perda foliar, nem na frutificação. Concluímos que os efeitos da exclusão de aves e morcegos na perda foliar e frutificação são modulados por diferentes processos que ocorrem no nível local e da paisagem. Sugerimos que quando a cobertura florestal local é alta (geralmente perto de fragmentos florestais), as aves e os morcegos não se alimentam apenas de herbívoros, mas também de mesopredadores. No entanto, quando a cobertura florestal local é baixa (e.g. longe de fragmentos florestais), os mesopredadores não ocorrem e aves e morcegos passam a prover serviço de controle biológico de pragas, alimentando-se principalmente de herbívoros. Destacamos a importância de empregar uma análise multiescalar em sistemas onde espécies com diferentes capacidades de dispersão proveem um serviço ecossistêmico. / Biological control of agricultural pests is one of the most important ecosystem services given its key role for agricultural production. Although several studies have shown that the abundance and richness of predators increase with the amount of native forest in the landscape, the underlying mechanisms relating forest cover at different spatial scales with the provision of biological control are still poorly understood. We experimentally excluded flying vertebrates (birds and bats) in eight coffee landscapes in the Brazilian Atlantic Forest, encompassing a gradient of forest cover and quantified the consequences for coffee leaf loss and fruit set. Leaf loss showed a negative relation with forest cover at landscape level, in landscapes with 2 km radius, indicating that herbivory is better controlled in landscapes with high forest cover, especially in the presence of birds and bats. However, at local level, 300 m around coffee plants, leaf loss and fruit set responded to forest cover differently. In units with low local forest cover exclusion of birds and bats increased leaf loss and reduced fruit set by 13% in mean. However, in units with high local forest cover, exclusion of birds and bats had no significant effect neither on leaf loss nor in fruit set. We concluded that the effects of birds and bats exclusion on leaf loss and fruit set are modulated by different processes occurring at landscape and local levels. We hypothesized that when local forest cover is high (usually near remnant forest fragments) birds and bats are not only controlling herbivores but may also be reducing mesopredators, while when local forest cover is low (e.g. far from forest fragments), mesopredators do not occur and birds and bats start providing biological pest control by feeding mainly on herbivores. We highlight the importance of employing a multiscale analysis in systems where species with different dispersal abilities are providing an ecosystem service.

Les interférons de Type I (IFN) sont des cytokines produites par les cellules en réponse à une infection virale. Les IFNs ont des effets pleïotropiques et parfois paradoxaux, protecteur ou néfaste pour l’immunité Innée ou adaptative. Certains facteurs intrinsèques (type cellulaire) peuvent expliquer une partie ces discordances. Mon travail de thèse s’est intéressé à l‘effet du microenvironnement cytokinique sur la réponse IFN. En utilisant des analyses à large échelle, nous avons étudié la réponse IFN dans 4 contextes de polarisation des lymphocytes T auxiliaires (Th). Nous avons identifié 1/ un programme de transcription conservé et 2/ une réponse IFN flexible, modulant spécifiquement les principales fonctions des Th (cytokines, chemokines) en fonction du contexte polarisant. La réponse antivirale apparait aussi flexible avec une moins bonne protection des Th2 et Th17 contre l’infection par HIV-1et HIV-2. Nos résultats suggèrent que l’environnement cytokinique contrôle en partie la réponse IFN et peut ainsi moduler cette dernière dans différents contextes physiopathologiques. / Type I IFN (IFN) are innate cytokines produced by host cells during viral infection. Ithas pleiotropic and sometimes opposing, protective or detrimental effects, on both innateand adaptive immunity that remain poorly understood. Parts of IFN response may be explain by intrinsic effect (cell-­‐specificity). My thesis was focused on the effect of the microenvironment, as present during T Helper cell differentiation, on IFN response. Using a systems level approach, we studied IFN responses during Four Human T Helper cell differentiation. We identified 1/ a conserved IFN-­‐induced transcriptional program comprising mostly antiviral genes 2/ a flexible IFN response, leading to a different pattern of chemokine and cytokine induction by IFN in distinct Th environments. Antiviral response was also flexible with a lesser protection to HIV-1 and HIV-2 infection in Th2 and Th17 contexts. Our in vitro results suggested that environmental control might shape the effects of IFN in different physiopathological contexts.

O controle biológico de pragas agrícolas é um dos serviços ecossistêmicos mais valorizados, dada sua importância para a produção agrícola. Embora vários estudos tenham demonstrado que a abundância e riqueza de predadores aumentam com a quantidade de floresta nativa, os mecanismos subjacentes que modulam a relação entre a cobertura florestal e provisão de controle biológico em diferentes escalas espaciais são ainda pouco conhecidos. Neste trabalho, utilizamos experimentos de exclusão de vertebrados voadores em oito paisagens cafeeiras na Mata Atlântica, num gradiente de cobertura florestal, e quantificamos as consequências para a perda foliar e para a frutificação. A perda foliar mostrou uma relação negativa com a cobertura florestal em paisagens com 2 km de raio, indicando que a herbivoria é melhor controlada em paisagens com alta cobertura florestal, especialmente na presença de aves e morcegos. No entanto, no nível local, 300 m ao redor das plantas de café, a perda foliar e a frutificação responderam diferentemente à cobertura florestal. Em unidades com baixa cobertura florestal local, a exclusão de aves e morcegos aumentou a perda foliar e diminuiu a frutificação em uma média de 13%. Por outro lado, em unidades com alta cobertura florestal local, a exclusão de aves e morcegos não teve efeitos significativos nem na perda foliar, nem na frutificação. Concluímos que os efeitos da exclusão de aves e morcegos na perda foliar e frutificação são modulados por diferentes processos que ocorrem no nível local e da paisagem. Sugerimos que quando a cobertura florestal local é alta (geralmente perto de fragmentos florestais), as aves e os morcegos não se alimentam apenas de herbívoros, mas também de mesopredadores. No entanto, quando a cobertura florestal local é baixa (e.g. longe de fragmentos florestais), os mesopredadores não ocorrem e aves e morcegos passam a prover serviço de controle biológico de pragas, alimentando-se principalmente de herbívoros. Destacamos a importância de empregar uma análise multiescalar em sistemas onde espécies com diferentes capacidades de dispersão proveem um serviço ecossistêmico. / Biological control of agricultural pests is one of the most important ecosystem services given its key role for agricultural production. Although several studies have shown that the abundance and richness of predators increase with the amount of native forest in the landscape, the underlying mechanisms relating forest cover at different spatial scales with the provision of biological control are still poorly understood. We experimentally excluded flying vertebrates (birds and bats) in eight coffee landscapes in the Brazilian Atlantic Forest, encompassing a gradient of forest cover and quantified the consequences for coffee leaf loss and fruit set. Leaf loss showed a negative relation with forest cover at landscape level, in landscapes with 2 km radius, indicating that herbivory is better controlled in landscapes with high forest cover, especially in the presence of birds and bats. However, at local level, 300 m around coffee plants, leaf loss and fruit set responded to forest cover differently. In units with low local forest cover exclusion of birds and bats increased leaf loss and reduced fruit set by 13% in mean. However, in units with high local forest cover, exclusion of birds and bats had no significant effect neither on leaf loss nor in fruit set. We concluded that the effects of birds and bats exclusion on leaf loss and fruit set are modulated by different processes occurring at landscape and local levels. We hypothesized that when local forest cover is high (usually near remnant forest fragments) birds and bats are not only controlling herbivores but may also be reducing mesopredators, while when local forest cover is low (e.g. far from forest fragments), mesopredators do not occur and birds and bats start providing biological pest control by feeding mainly on herbivores. We highlight the importance of employing a multiscale analysis in systems where species with different dispersal abilities are providing an ecosystem service.

This thesis deals with modeling of two types of fuel cells:the polymer electrolyte fuel cell (PEFC) and the directmethanol fuel cell (DMFC), for which we address four majorissues: a) mass transport limitations; b) water management(PEFC); c) gas management (DMFC); d) thermal management. Four models have been derived and studied for the PEFC,focusing on the cathode. The first exploits the slenderness ofthe cathode for a two-dimensional geometry, leading to areduced model, where several nondimensional parameters capturethe behavior of the cathode. The model was extended to threedimensions, where four di.erent flow distributors were studiedfor the cathode. A quantitative comparison shows that theinterdigitated channels can sustain the highest currentdensities. These two models, comprising isothermal gasphaseflow, limit the studies to (a). Returning to a two-dimensionalgeometry of the PEFC, the liquid phase was introduced via aseparate flow model approach for the cathode. In addition toconservation of mass, momentum and species, the model wasextended to consider simultaneous charge and heat transfer forthe whole cell. Di.erent thermal, flow fields, and hydrodynamicconditions were studied, addressing (a), (b) and (d). A scaleanalysis allowed for predictions of the cell performance priorto any computations. Good agreement between experiments with asegmented cell and the model was obtained. A liquid-phase model, comprising conservation of mass,momentum and species, was derived and analyzed for the anode ofthe DMFC. The impact of hydrodynamic, electrochemical andgeometrical features on the fuel cell performance were studied,mainly focusing on (a). The slenderness of the anode allows theuse of a narrow-gap approximation, leading to a reduced model,with benefits such as reduced computational cost andunderstanding of the physical trends prior to any numericalcomputations. Adding the gas-phase via a multiphase mixtureapproach, the gas management (c) could also be studied.Experiments with a cell, equipped with a transparent end plate,allowed for visualization of the flow in the anode, as well asvalidation of the two-phase model. Good agreement betweenexperiments and the model was achieved. Keywords:Fuel cell; DMFC; PEFC; one-phase; two-phase;model; visual cell; segmented cell; scale analysis; asymptoticanalysis.

A multi-domain homogenization method is proposed and developed in this thesis based on a two-scale technique. The method is capable of analyzing composite structures with several periodic distributions by partitioning the entire domain of the composite into substructures making use of the classical homogenization theory following a first-order standard continuum mechanics formulation. The need to develop the multi-domain homogenization method arose because current homogenization methods are based on the assumption that the entire domain of the composite is represented by one periodic or quasi-periodic distribution. However, in some cases the structure or composite may be formed by more than one type of periodic domain distribution, making the existing homogenization techniques not suitable to analyze this type of cases in which more than one recurrent configuration appears. The theoretical principles used in the multi-domain homogenization method were applied to assemble a computational tool based on two nested boundary value problems represented by a finite element code in two scales: a) one global scale, which treats the composite as an homogeneous material and deals with the boundary conditions, the loads applied and the different periodic (or quasi-periodic) subdomains that may exist in the composite; and b) one local scale, which obtains the homogenized response of the representative volume element or unit cell, that deals with the geometry distribution and with the material properties of the constituents. The method is based on the local periodicity hypothesis arising from the periodicity of the internal structure of the composite. The numerical implementation of the restrictions on the displacements and forces corresponding to the degrees of freedom of the domain's boundary derived from the periodicity was performed by means of the Lagrange multipliers method. The formulation included a method to compute the homogenized non-linear tangent constitutive tensor once the threshold of nonlinearity of any of the unit cells has been surpassed. The procedure is based in performing a numerical derivation applying a perturbation technique. The tangent constitutive tensor is computed for each load increment and for each iteration of the analysis once the structure has entered in the non-linear range. The perturbation method was applied at the global and local scales in order to analyze the performance of the method at both scales. A simple average method of the constitutive tensors of the elements of the cell was also explored for comparison purposes. A parallelization process was implemented on the multi-domain homogenization method in order to speed-up the computational process due to the huge computational cost that the nested incremental-iterative solution embraces. The effect of softening in two-scale homogenization was investigated following a smeared cracked approach. Mesh objectivity was discussed first within the classical one-scale FE formulation and then the concepts exposed were extrapolated into the two-scale homogenization framework. The importance of the element characteristic length in a multi-scale analysis was highlighted in the computation of the specific dissipated energy when strain-softening occurs. Various examples were presented to evaluate and explore the capabilities of the computational approach developed in this research. Several aspects were studied, such as analyzing different composite arrangements that include different types of materials, composites that present softening after the yield point is reached (e.g. damage and plasticity) and composites with zones that present high strain gradients. The examples were carried out in composites with one and with several periodic domains using different unit cell configurations. The examples are compared to benchmark solutions obtained with the classical one-scale FE method. / En esta tesis se propone y desarrolla un método de homogeneización multi-dominio basado en una técnica en dos escalas. El método es capaz de analizar estructuras de materiales compuestos con varias distribuciones periódicas dentro de un mismo continuo mediante la partición de todo el dominio del material compuesto en subestructuras utilizando la teoría clásica de homogeneización a través de una formulación estándar de mecánica de medios continuos de primer orden. La necesidad de desarrollar este método multi-dominio surgió porque los métodos actuales de homogeneización se basan en el supuesto de que todo el dominio del material está representado por solo una distribución periódica o cuasi-periódica. Sin embargo, en algunos casos, la estructura puede estar formada por más de un tipo de distribución de dominio periódico. Los principios teóricos desarrollados en el método de homogeneización multi-dominio se aplicaron para ensamblar una herramienta computacional basada en dos problemas de valores de contorno anidados, los cuales son representados por un código de elementos finitos (FE) en dos escalas: a) una escala global, que trata el material compuesto como un material homogéneo. Esta escala se ocupa de las condiciones de contorno, las cargas aplicadas y los diferentes subdominios periódicos (o cuasi-periódicos) que puedan existir en el material compuesto; y b) una escala local, que obtiene la respuesta homogenizada de un volumen representativo o celda unitaria. Esta escala se ocupa de la geometría, y de la distribución espacial de los constituyentes del compuesto así como de sus propiedades constitutivas. El método se basa en la hipótesis de periodicidad local derivada de la periodicidad de la estructura interna del material. La implementación numérica de las restricciones de los desplazamientos y las fuerzas derivadas de la periodicidad se realizaron por medio del método de multiplicadores de Lagrange. La formulación incluye un método para calcular el tensor constitutivo tangente no-lineal homogeneizado una vez que el umbral de la no-linealidad de cualquiera de las celdas unitarias ha sido superado. El procedimiento se basa en llevar a cabo una derivación numérica aplicando una técnica de perturbación. El tensor constitutivo tangente se calcula para cada incremento de carga y para cada iteración del análisis una vez que la estructura ha entrado en el rango no-lineal. El método de perturbación se aplicó tanto en la escala global como en la local con el fin de analizar la efectividad del método en ambas escalas. Se lleva a cabo un proceso de paralelización en el método con el fin de acelerar el proceso de cómputo debido al enorme coste computacional que requiere la solución iterativa incremental anidada. Se investiga el efecto de ablandamiento por deformación en el material usando el método de homogeneización en dos escalas a través de un enfoque de fractura discreta. Se estudió la objetividad en el mallado dentro de la formulación clásica de FE en una escala y luego los conceptos expuestos se extrapolaron en el marco de la homogeneización de dos escalas. Se enfatiza la importancia de la longitud característica del elemento en un análisis multi-escala en el cálculo de la energía específica disipada cuando se produce el efecto de ablandamiento. Se presentan varios ejemplos para evaluar la propuesta computacional desarrollada en esta investigación. Se estudiaron diferentes configuraciones de compuestos que incluyen diferentes tipos de materiales, así como compuestos que presentan ablandamiento después de que el punto de fluencia del material se alcanza (usando daño y plasticidad) y compuestos con zonas que presentan altos gradientes de deformación. Los ejemplos se llevaron a cabo en materiales compuestos con uno y con varios dominios periódicos utilizando diferentes configuraciones de células unitarias. Los ejemplos se comparan con soluciones de referencia obtenidas con el método clásico de elementos finitos en una escala.

The molten pool shape and thermocapillary convection during melting or welding of metals or alloys are self-consistently predicted from scale analysis. Determination of the molten pool shape and transport variables is crucial due to its close relationship with the strength and properties of the fusion zone. In this work, surface tension coefficient is considered to be negative, indicating an outward surface flow, whereas high Prandtl number represents a thinner thickness of the thermal boundary layer than that of momentum boundary layer. Since Marangoni number is usually very high, the domain of scaling is divided into the hot, intermediate and cold corner regions, boundary layers on the solid-liquid interface and ahead of the melting front. The results find that the width and depth of the pool, peak and secondary surface velocity, and maximum temperatures in the hot and cold corner regions can be explicitly and separately determined as functions of working variables or Marangoni, Prandtl, Peclet, Stefan, and beam power numbers. The scaled results agree with numerical data, different combinations among scaled equations, and available experimental data.

The molten pool shape and thermocapillary convection in melting or welding of metals or alloys having negative surface tension coefficients and Prandtl number greater than unity are determined from a scale analysis. Negative surface tension coefficient indicates that the surface flow is in outward direction, while Prandtl number greater than unity represents that boundary layer thickness of conduction is less than that of momentum. Determination of the molten pool shape is crucial due to its close relationship with the strength, microstructure and properties of the fusion zone. Since Marangoni and Reynolds number are usually greater than ten thousands, transport processes can be determined by scale analysis. In this work, the molten pool is divided into the hot, intermediate and cold corner regions on the flat free surface, boundary layers on the solid-liquid interface and ahead of the melting front for analysis. The results find that the pool shape, surface speed and temperature profiles can be self-consistently evaluated as functions of Marangoni, Prandtl, Peclet, Stefan, and beam power numbers. The predictions agree with numerical computations and experimental data in the literature.

<p>This thesis deals with modeling of two types of fuel cells:the polymer electrolyte fuel cell (PEFC) and the directmethanol fuel cell (DMFC), for which we address four majorissues: a) mass transport limitations; b) water management(PEFC); c) gas management (DMFC); d) thermal management.</p><p>Four models have been derived and studied for the PEFC,focusing on the cathode. The first exploits the slenderness ofthe cathode for a two-dimensional geometry, leading to areduced model, where several nondimensional parameters capturethe behavior of the cathode. The model was extended to threedimensions, where four di.erent flow distributors were studiedfor the cathode. A quantitative comparison shows that theinterdigitated channels can sustain the highest currentdensities. These two models, comprising isothermal gasphaseflow, limit the studies to (a). Returning to a two-dimensionalgeometry of the PEFC, the liquid phase was introduced via aseparate flow model approach for the cathode. In addition toconservation of mass, momentum and species, the model wasextended to consider simultaneous charge and heat transfer forthe whole cell. Di.erent thermal, flow fields, and hydrodynamicconditions were studied, addressing (a), (b) and (d). A scaleanalysis allowed for predictions of the cell performance priorto any computations. Good agreement between experiments with asegmented cell and the model was obtained.</p><p>A liquid-phase model, comprising conservation of mass,momentum and species, was derived and analyzed for the anode ofthe DMFC. The impact of hydrodynamic, electrochemical andgeometrical features on the fuel cell performance were studied,mainly focusing on (a). The slenderness of the anode allows theuse of a narrow-gap approximation, leading to a reduced model,with benefits such as reduced computational cost andunderstanding of the physical trends prior to any numericalcomputations. Adding the gas-phase via a multiphase mixtureapproach, the gas management (c) could also be studied.Experiments with a cell, equipped with a transparent end plate,allowed for visualization of the flow in the anode, as well asvalidation of the two-phase model. Good agreement betweenexperiments and the model was achieved.</p><p><b>Keywords:</b>Fuel cell; DMFC; PEFC; one-phase; two-phase;model; visual cell; segmented cell; scale analysis; asymptoticanalysis.</p>

The peer group is a dynamic context within which children and adolescents have a wide range of experiences, both positive and negative. Friendships provide support and a sense of belonging; however, friendships can also be contexts within which competition and aggression occur. During childhood and adolescence, aggression and victimization are likely to occur in the school context and in situations where several members of the peer group are present and sometimes actively (or passively) participating. In the seminal work related to bullying as a group process, Salmivalli and colleagues identified distinct roles that children take when enacting aggression (Salmivalli et al., 1996). Salmivalli's work, in the area of participant roles, however, has focused on overt bullying, a specific subtype of aggression which has a specific meaning within the peer relations literature. To date, the participant roles have not been measured within the context of overt and relational aggression. The purpose of the present study is to examine the psychometric properties of the Overt Aggression Participant Role Scale (OAPRS) and the Relational Aggression Participant Role Scale (RAPRS), two new scales designed by the author, to measure the aggressor, assistant, reinforcer, defender, outsider, and victim roles during acts aggression, as opposed to bullying. Additional goals include: 1) exploring the associations among the roles, 2) examining measurement equivalence across gender and grade level, and 3) exploring associations of the participant roles with measures of sociometric status and depressive symptoms. Findings point toward the psychometric properties of the two scales being quite robust. The data fit the 12 factor model and the scales measure the constructs equivalently across gender and three grade groups. The aggressor, assistant, and reinforcer roles were strongly associated as were the aggressor and victim roles. Several relational roles were highly overlapping, suggesting reciprocity of roles. Few meaningful gender or grade level differences were found resulting in more similarity in the overt and relational roles than differences. The outsider role was the only role not associated with depressive symptoms. Implications for prevention and intervention are discussed.

Numerous studies have looked at attitudes about sexual assault, or rape myths, but most of these studies have looked at sexual assault when victims are female and perpetrators are male. However, female-to-male rape does occur, and male victims experience negative consequences from the event. The aim of the present investigation was to develop a scale to measure acceptance of female-to-male rape myths. The investigation involved two separate phases that build on a pilot study in which a preliminary scale was developed. The first phase of the investigation identified male rape myths that are pertinent to female-to-male rape. The second phase developed the items of the scale from the rape myths identified in Phase 1 and evaluated the factor structure, reliability and validity of the scale. The Female-to-Male Rape Myths Scale (FMRM) consists of 30 items and was found to be a reliable and valid measure of female-to-male rape myth acceptance in Midwestern college students. The construct was found to be unifactorial with good internal consistency at .94. Scores on the FMRM correlated with scores on the Ambivalent Sexism Inventory (Glick & Fiske, 1996), the Attitudes Toward Lesbians and Gay Men Scale (Herek, 1988), and the Male Rape Myths Scale (Kerr Melanson, 1999). Implications for future research and practical uses of the scale are discussed. / Department of Counseling Psychology and Guidance Services