A presente dissertação trata de um estudo teórico-experimental sobre escoamento monofásico e bifásico em um dissipador de calor baseado em microcanais. Este tipo de dissipador de calor tem sido usado para a intensificação da troca de calor em sistemas compactos e de alto desempenho. A intensificação da troca de calor promovida pelo escoamento em microcanais é acompanhada de um incremento na perda de pressão, portanto o estudo destes dois parâmetros é essencial para o entendimento dos fenômenos relacionados e fundamental para o desenvolvimento de ferramentas de projeto para dissipadores de calor baseados em microcanais. Inicialmente, um levantamento bibliográfico extenso sobre a ebulição convectiva em microcanais de reduzido diâmetro foi realizado. Este estudo da literatura trata de critérios de transição entre micro- e macro-escala, padrões de escoamento, métodos de previsão do coeficiente de transferência de calor e perda de pressão. Atenção específica foi dada a estudos de dissipadores de calor baseados em microcanais. Com base nesta análise da literatura, uma bancada experimental foi confeccionada para que dados experimentais de transferência de calor e perda de pressão pudessem ser levantados a partir de um dissipador de calor de microcanais. O dissipador de calor fabricado para este estudo é constituído de 50 microcanais retangulares dispostos paralelamente com 15 mm de comprimento, 100 µm de largura, 500 µm de profundidade e espaçados entre si de 200 µm. Experimentos foram executados para o R134a, velocidades mássicas de 400 a 1500 kg/m²s, título de vapor máximo de 0,35 e fluxos de calor de até 310 kW/m². Como conclusão deste trabalho observa-se perda de pressão elevada em relação aos valores fornecidos pelos métodos de previsão da literatura e um coeficiente de transferência de calor próximo ao estimado pelo modelo de três zonas proposto por Thome et al. (2004). / This study presents a theoretical and experimental investigation on single and two-phase flows in a microchannel based heat sink. Multi-microchannel heat sinks are able of dissipating extremely high heat fluxes under confined conditions. Such characteristics have attracted the attention of academia and industry and actually several studies are being carried out in order to evaluate and optimize such devices. Initially, an extensive investigation of the literature concerning convective boiling in micro-scale channels was performed. This literature review covers transitional criteria between micro- and macro-scale flow boiling, two phase flow patterns, heat transfer coefficient and pressure drop during convective boiling. Special attention was given to studies concerning microchannels based heat sinks. Based on this investigation, an experimental facility was built for performing heat transfer and pressure drop measurements during single-phase flow and flow boiling in microchannel based heat sinks. For this study, a microchannel based heat sink was also manufactured. The heat sink contains 50 rectangular parallel microchannels, 15 mm long, 100 µm wide by 500 µm deep and separated by 200 µm walls. Experiments were performed for R134a, mass velocity of 400-1500 kg/m²s, maximum vapor quality of 0,35 and heat fluxes up to 310 kW/m². The database obtained in the present study was compared against pressure drop and heat transfer coefficient prediction methods from the literature. It was found that no one method is accurate in predicting heat sink pressure drop while heat transfer coefficient results were accurately predicted by the 3-zone model proposed by Thome et al. (2004).

Madagascar est un lambeau de croûte continentale archéenne à néoproterozoïque entouré de marges transformantes, obliques et divergentes : la marge oblique du bassin de Morondava à l’Ouest, bornée par la ride de Davie, et au Nord, la marge divergente du bassin de Majunga connectée au bassin de Somalie. Cette île de 1600 kilomètres de long est composée d’un plateau axial archéen-protérozoïque entre 1200 et 1800m d’altitude, bordé de tous côtés par des bassins sédimentaires. Le sommet du plateau correspond à des surfaces d’aplanissement altérées, délimitées par des escarpements plus ou moins marqués. L'altitude des hauts plateaux traduit l'existence de processus mantelliques, mais la cinétique et l'origine du relief malgache est mal comprise. Peu d'études ont étudié les domaines non orogéniques dans leur intégralité terre-mer, depuis le bassin versant en érosion jusqu'aux marges en sédimentation, et aucune d'entre elles ne porte sur Madagascar. Ce travail de thèse repose donc sur une double approche: une analyse géomorphologique des formes du relief (surfaces d'aplanissement) à terre, basée sur leur (i) cartographie, (ii) chronologie relative, (iii) relation avec les profils d'altération et (iv) datation au moyen des placages sédimentaires et du volcanisme daté qui les scellent; une analyse stratigraphique de l'intervalle post-rift des marges, basée sur l'interprétation de données de sub-surface (puits et lignes sismiques), lesquelles ont été réévaluées en âge (biostratigraphie), pour (i) identifier, dater et mesurer les déformations des marges et de leur relief en amont, (ii) mesurer les flux silicoclastiques, produits de l'érosion continentale. Un calendrier et une cartographie des déformations ont été obtenus sur les marges et mis en relation avec les différentes générations de surfaces d'aplanissement étagées caractérisant le relief malgache. Au Crétacé supérieur, une flexuration de l'île est initiée au sud, à grande longueur d'onde, autour de ~94 Ma. Cette déformation est scellée par la mise en place d'une surface d'aplanissement non déformée mise en place entre 80 et 66 Ma. Durant le Paléocène jusqu’à l'Eocène supérieur (66 à 20 Ma), Madagascar est une île relativement plate, de faible altitude, entourée de larges plateformes carbonatées. Ce relief est largement altéré avec la croissance de nombreux profils latéritiques et les influx silico-clastique dans les bassins sont alors relativement faibles. Le Miocène moyen à supérieur correspond au paroxysme de la surrection et de la déformation avec (1), le basculement de la marge ouest (Morondava), (2) une augmentation du flux de sédimentation silicoclastique depuis le Miocène moyen et (3) la mise en place d’une succession de quatre surfaces d’aplanissement correspondant à des pics d'intensité de la déformation. Le résultat de cette surrection est la morphologie en dôme de l’île de Madagascar (avec un plateau central) marquée par la forme concave de la surface crétacé supérieure altérée à l’Eocène. Le mécanisme de la surrection doit prendre en compte une déformation de très grande longueur d’onde (x 1000 km), forcément liée à la dynamique mantellique. Les relations avec les dômes d’Afrique de l’Est (Ethiopie, Afrique du Sud) sont discutées. / Madagascar is an Archean to Neoproterozoic continental crust surrounded by transform, oblique and divergent margins: the transform Morondava basin to the west, pounded by the Davie Fracture Zone, and to the north, the divergent Mahajanga Basin connected to the Somali Oceanic Basin. This 1600 km long island is a high axial plateau with elevations from 1200 to 1800m. The top of the plateau corresponds to weathered planation surfaces (etchplains), bounded by more or less high scarps. Such elevation of the high axial plateau imply mantle processes, but the age and cinetic of the uplift is still poorly known. Few studies dealt with anorogenic domains in their entirety from the catchment area, the source, to the downstream depositional system, the sink, none of which is about Madagascar. This work lies on a double approach : it is onshore based on the analysis of the macroforms (planation surfaces, etchplains, pediments) throughout their (i) mapping, (ii) relative dating, (iii) relationships with weathering profiles and (iv) dating by their intersection with preserved sediments and volcanism (lava flow and intrusions). offshore, it is based on the interpretation of a dataset of seismic lines and industrial wells, coupled with refreshed biostratigraphy, in order to (i) identify, date and measure vertical movements of the margins and upstream reliefs. Chronology and mapping of vertical movements were defined on the Morondava margin and compared with the onset of the stepped planation surfaces typical of Madagascar topography. During Upper Cretaceous, the southern part of the island is uplifted, at ~94 Ma. This deformation is sealed by the onset of an undeformed planation surface between 80 and 66 ma. From Paleocene to Upper Eocene (66 to 20 Ma), Madagascar is a flat, low elevated island, surrounded by wide carbonate platforms. The relief is highly weathered with growth of lateritic profiles and silico-clastic influx within the basin is low. During Middle to Upper Miocene is the uplift and doming paroxysm with (1), tilt of the western margin (Morondava), (2) increase of silico-clastic influx from Middle Miocene and (3 the onset of four planation surfaces associated to deformation paroxysms. The end result of this uplift is a convex up shape pattern for the end Cretaceous surface weathered during Eocene times, creating the present-day dome morphology (with a central plateau) of Madagascar. The mechanism of this uplift has to explain a very long wavelength deformation (x1000 km) necessary due to mantle dynamics. The relationships with the other East African domes (Ethiopia, East Africa, South Africa) are discussed.

Les relations entre l'activité de la source et l'activité du puits contrôlent en grande partie la croissance des plantes. Ces activités varient au cours du développement, mais aussi en réponse à des changements des conditions environnementales. Notre étude avait pour but d'identifier le rôle du métabolisme carboné dans la réponse de la croissance d'E. americanum à la modulation des activités de la source et du puits. Dans une première partie, l'activité du puits est modulée par la température de croissance. Aux fortes températures, l'activité du puits est plus élevée, alors que sa capacité est réduite. Ces effets, dus à la modulation du métabolisme du saccharose, mènent à une saturation précoce en amidon des bulbes à forte température. Par la suite, la baisse de la demande en carbone du puits induit un rétrocontrôle négatif de l'activité photosynthétique et finalement, la sénescence foliaire. À l'inverse, l'activité du puits à faible température est en rythme avec l'accroissement de la capacité, menant à une biomasse supérieure du bulbe en fin de croissance épigée. Dans une seconde partie, l'activité de la source est modulée en changeant la concentration en CO2 et en O3. Malgré la stimulation de la source sous fort CO2 et son inhibition sous fort O3, l'accumulation d'amidon et la biomasse du bulbe ne sont pas affectées. En effet, le surplus de carbone parvenant au puits est brûlé par la voie alternative de la respiration, celle-ci étant stimulée par l'activité de l'enzyme malique. La voie alternative de la respiration évite ainsi une saturation hâtive en amidon et éventuellement, une sénescence foliaire précoce. Dans une dernière partie, l'activité de la source est modulée par l'irradiance et la photopériode. L'accumulation d'amidon varie en fonction de la photopériode alors que l'irradiance n'a aucun effet. De plus, l'activité photosynthétique est inhibée très précocement sous longue photopériode. Cette inhibition semble due à un déséquilibre entre la quantité totale de carbone fixé par jour et son utilisation suite à son transfert au sein du bulbe. Nous pouvons donc conclure que les régulations du métabolisme carboné permettent d'ajuster l'activité du puits à la capacité de celui-ci chez l’E. americanum / Relationships between source and sink activities largely control the growth of plants. Both activities vary during development as well as in response to changes in environmental conditions. The aim of our study was to identify the role carbon metabolism plays in the response of E. americanum growth to changes in source and sink activities. Firstly, sink activity is modulated by changing growth temperature. Sink activity is higher at higher temperatures, whereas sink capacity is more restricted. These effects, due to the modulation of sucrose metabolism, lead to an earlier starch saturation of bulbs at higher temperature. Thereafter, the reduction in carbon sink demand induces a feedback inhibition of photosynthetic activity and finally, leaf senescence. In contrast, sink activity at low temperature is more in rhythm with the increasing sink capacity, leading to larger bulbs at the end of the epigeous growth season. Secondly, source activity is modulated by changing CO2 and O3 concentrations. Despite a stimulation of the source activity under high CO2 and its inhibition under high O3, neither plant growth nor starch accumulation was affected. Indeed, excess carbon translocated within the sink is burned by the alternative respiratory pathway. This pathway is stimulated by malic enzyme. Alternative respiratory pathway thus avoids an early starch saturation of the bulb and eventually, an early leaf senescence. Finally, source activity is also modulated by changing irradiance and photoperiod regimes. Starch accumulation changes in response to photoperiod but not to irradiance. Furthermore, photosynthetic activity is inhibited early in the season under long photoperiod. This inhibition seems due to an imbalance between the total amount of carbon fixed per day and its utilisation following translocation to the bulb. We can thus conclude that regulation of carbon metabolism allow to adjust sink activity to sink capacity in E. americanum.

La convection turbulente dans des géométries régulières et complexes trouve son importance dans de nombreuses applications industrielles, notamment les échangeurs de chaleurs (dissipateurs à picots). L’objectif de ce travail est de faire une étude diagnostic sur la qualité d’échange thermique dans des géométries représentatives d’échangeurs de chaleur, en utilisant la simulation numérique comme outil d’investigation. L’approche qui sera utilisée est basée sur la résolution des équations de Navier-Stockes (moyennées) RANS avec les modèles statistiques.La finalité des résultats est de proposer des solutions pour promouvoir l’échange de chaleur dans ce type de configuration à petites échelles (micro systèmes de dissipateurs de chaleur à picots). Pouvoir déterminer une nouvelle approche pour le calcul du coefficient d’échange moyen par convection (coefficient d’échange convectif) dans des géométries complexes et compactes, et adopter une nouvelle approche pour calculer les températures de référence. Proposition et adaptation d’une nouvelle forme de géométrie pour une éventuelle optimisation du modèle existant (picots en forme losange). / The turbulent convection in regular and complex geometries is important in many industrial applications including mini/micro heat exchangers (pin-fins heat sinks). The objective of this work is to conduct a parametric study of the quality of heat exchange in representative forms of geometries of mini-channels, by using numerical simulation as an investigative tool. The approach taken is based on solving Averaged Navier-Stokes equations, RANS approach with the statistical models.The purpose of the results is to propose solutions to promote the exchange of heat in this type of configuration (micro systems of pin-fins heat sinks). Get a new approach for the calculation of averaged heat transfer coefficient in complex and compact geometries, and adopt a new approach to calculate reference temperatures. Suggestion and adaptation of a new form of geometry for an eventual optimization of the existing model (diamond shaped pin-fins).

Coffee (Coffea arabica L.) nutrient demand depends on fruit load and intensity of the annual variation of vegetative growth. However, nutrient rates recommended for this crop are based only on bean yield, manily yields of old crops. Therefore, this research aimed to determine the source-sink relationship, through the effect of fruit load on vegetative growth, to understand coffee nutritional demand. The hypotheses were (i) the annual biomass of stem, branches and leaves should have a strong negative linear relationship regarding fruit load, (ii) the average nutrients concentration changes in the vegetative plant part due to the number of fruits, and (iii) the plant nutrient demand varies in years of high and low production due to the different proportions between fruiting and annual vegetation. The study was carried out from November 2015 to June 2016 in coffee trees in the municipality of Jacuí - MG, Brazil. The experimental design was completely randomized with one factor (fruit load), six factor levels (100%, 80%, 60%, 40%, 20% and 0%) and five replicates. After flowering, in early November 2015, six fruit loads were manually imposed and the base of the last pair of fully expanded leaf was labeled with wire on all branches of the trees. In early June 2016, during the coffee harvest, branches were cut from the wire-label and characterized. The variables analyzed were: numbers of nodes, leaf area, dry vegetation yield, dry bean yield, volume of fruits and concentration of macro and micro nutrients in vegetation and fruiting. The study revealed that fruit load strongly affects vegetative growth in Coffee arabica L. For each liter of fruit produced, ~ 103 g of dry vegetation yield decreases per tree. Furthermore, the concentration of the macronutrients N, P, K, Mg and S and the micronutrients Mn, Fe, Cu and Zn in vegetation and fruiting not dependent on fruit load. Nutrient demand of a given plant density varies in years of high and low production due to the different yield proportions of mass between fruiting and annual vegetation. / A demanda de nutrients do cafeeiro (Coffea arabica L.) depende da carga de frutos e da intensidade da variação anual do crescimento vegetativo. No entanto, as doses de nutrientes recomendadas para a cultura são baseadas apenas na produtividade de frutos, especialmente produtividades de lavouras antigas. Portanto, o objetivo principal desta pesquisa foi determinar a relação fonte-dreno, por meio do efeito da carga de frutos no crescimento vegetativo, para compreender a demanda nutricional do café. As hipóteses foram (i) a biomassa vegetativa anual teria uma forte relação linear negativa em função da carga de frutos, (ii) a concentração média de nutrientes seria variável na parte vegetativa da planta devido à quantidade de frutos e (iii) a demanda de nutrientes variaria em anos de alta e baixa produção devido às diferentes proporções entre frutificação e vegetação anual. O experimento foi realizado de novembro de 2015 a junho de 2016 em Jacuí - MG, Brasil. O delineamento experimental foi inteiramente casualizado com um fator (carga de frutos), seis níveis do fator (100%, 80%, 60%, 40%, 20% e 0%) e cinco repetições. Após o florescimento, no início de novembro de 2015, as seis cargas de frutos foram aplicadas manualmente e a base do último par de folhas totalmente expandidas foi marcada com um arame indicador em todos os ramos das plantas. No início de junho de 2016, durante o período de colheita do café, os ramos foram cortados a partir do arame indicador e caracterizados. As variáveis analisadas foram: número de nós, área foliar, massa seca da vegetação, massa seca de frutos, volume de frutos e concentração de macro e micronutrientes na vegetação e na frutificação. O estudo revelou que a carga de frutos afeta fortemente o crescimento vegetativo de Coffee arabica L. Para cada litro de fruto produzido a planta deixa de vegetar ~ 103 g de massa seca. Além disso, as concentrações dos macronutrientes N, P, K, Mg e S e os micronutrientes Mn, Fe, Cu e Zn na vegetação e na frutificação não dependeram da carga de frutos. A demanda de nutrientes de uma dada densidade de plantas varia em anos de alta e baixa produção devido às diferentes proporções de produção de massa entre frutificação e vegetação anual.

Dans cette thèse, on présente une étude numérique de la convection forcée turbulente dans un dissipateur thermique muni d'une chicane transversale dans le by-pass. Le premier modèle est composé d’ailettes planes et le second consiste à ajouter des ailettes broches entre les ailettes planes. Les équations gouvernantes basées sur le modèle de turbulences k- SSt sont discrétisées et résolues par la méthode des volumes finis et l'algorithme SIMPLE. Les résultats dynamiques sont présentés en en termes de champs de vitesse, des profils de vitesse axiales dans des sections choisies ainsi que la perte de charge. L'étude thermique est présentée en terme de champs de température et de distribution du nombre de Nusselt. Un rapport entre les performances thermique et dynamique est présenté pour évaluer les différents dissipateurs thermiques. / In this thesis, we present an numerical study of turbulent forced convection in a heat sink provided with a transverse baffle in the bypass. The first model is composed of plates fins and the second consists of adding pin fins between the plates fins. The governing equations, based on the k- SSt turbulence model, are disscredized and solved by the finite volume method and the SIMPLE algorithm. Dynamic results are presented in terms of velocity fields, profiles of the axial velocities in selected sections and pressure drop. The thermal study is presented in terms of temperature fields and the distribution of Nusselt number. A ratio between the thermal and dynamic performances is presented to evaluate the different heat sinks.

As plantas de café (Coffea arabica L.) têm padrão de produção bienal em razão da competição entre o crescimento vegetativo e reprodutivo que ocorrem ao mesmo tempo. A quantificação de compostos de carbono e nitrogênio, bem como o perfil metabólico desses compostos foram investigados a fim de identificar possíveis alterações do crescimento dos tecidos que compõem o ramo produtivo do cafeeiro em resposta à carga de frutos. Os efeitos da carga de frutos foram estudados em quatro estádios fenológicos (expansão inicial, expansão final, granação e maturação de frutos), avaliando-se o crescimento de folhas velhas, maduras e novas; a secção dos ramos em que elas estão inseridas, assim como os frutos. Para isso, manipulações na carga de frutos foram realizadas na planta inteira cultivada em experimento de campo na região de Presidente Olegário, Minas Gerais, Brasil (18° 35\' 25\" S e 46° 19\' 20\" O; 1045 m de altitude). Os tratamentos consistiram em reduzir as cargas de frutos em seu estágio inicial de desenvolvimento a 0%, 30%, 60% e controle mantendo 100% do frutos na árvore. Este estudo demostrou que a alta carga de frutos prejudica principalmente o crescimento da vegetação nova, mas sem nenhum efeito sobre as folhas e ramos já formados. Também foi evidenciado que a alta carga de frutos promove competição entre os frutos afetando o seu tamanho e sua massa unitária. Essa redução do crescimento vegetativo e de frutos se deve principalmente pelo esgotamento de amido nos ramos que contribuem fortemente para o aporte de carbono para os órgãos dreno. A folha velha fornece sacarose para promover o crescimento vegetativo e de frutos, mas esse suprimento de carbono parece não ser suficiente para manutenção do crescimento dos frutos em excesso. Neste caso, o amido é então consumido dos ramos dessas plantas resultando no aumento do teor de sacarose nos ramos e folhas maduras, os quais são os maiores responsáveis por destinar carbono para o crescimento e desenvolvimento dos frutos. Em plantas com carga de frutos reduzida, os órgãos fonte de carbono são diferentes das plantas com alta produção de frutos. Neste caso, o ramo e folha madura fornecem sacarose para o crescimento da vegetação nova e frutos sem gasto aparente do amido acumulado nos ramos. As folhas e os ramos velhos são os principais contribuintes imediatos de nitrogênio, mas os ramos são os principais órgãos fonte desse nutriente tendo grande capacidade de armazenar nitrogênio e de disponibilizá-lo para as plantas sob alta produção de frutos. Assim, o nitrogênio e carbono armazenado nos ramos têm papel fundamental para tamponar a depleção desses nutrientes causada pelo número excessivo de drenos metabólicos. Os frutos das plantas com carga reduzida parecem ter sido sombreados pelo abundante crescimento de folhas e ramos de forma distinta dos frutos oriundos das plantas com carga excessiva de frutos. Esse sombreamento parece ter ocasionado menor grau de maturação dos frutos dessas plantas em razão do aumento dos compostos fenólicos e redução de pectina e antocianina nos frutos e/ou nos seus tecidos. Entretanto, esse efeito sobre a maturação dos frutos é tênue não alterando a quantidade de sacarose e aminoácidos solúveis totais nos frutos e em nenhum dos tecidos que os compõem. Utilizando uma abordagem metabolômica, foi confirmada que os ácidos orgânicos foram influenciados pelo menor grau de maturação dos frutos oriundos das plantas com carga reduzida. Essa evidência também suporta a ideia de que o maior crescimento vegetativo das plantas com carga reduzida pode aumentar o tempo de maturação dos frutos. Analisando o perfil de aminoácidos, foi confirmada que as folhas velhas e maduras são os órgãos fonte principais de nitrogênio para os drenos fisiológicos. A redistribuição de nitrogênio dessas folhas na forma de asparagina, glutamina, tirosina e fenilalanina para os drenos ocorreu em plantas com carga de frutos excessiva. Esse fluxo de nitrogênio para os drenos fisiológicos em conjunto com a degradação de proteínas dos ramos dessas plantas culminaram com aumento de fenialanina nos grãos, glutamina e aspartato nos frutos e alanina nas folhas novas em comparação com as plantas com carga de frutos reduzida. Houve estímulo da síntese de putrescina nos grãos provavelmente como um mecanismo para reajustar o fluxo de carbono e nitrogênio no organismo vegetal inicialmente pertubado em resposta à carga de frutos. Neste sentido, novas investigações pré e pós traducionais precisam ser desenvolvidas a fim de elucidar a interrelação do metabolismo de carbono e nitrogênio para a homeostase de seus metabólitos em resposta à carga de frutos. / Coffee plants (Coffea arabica L.) have a biennial production pattern because of the competition between vegetative and reproductive growth occurring at the same time. The quantification of carbon and nitrogen compounds as well as the metabolic profile of these compounds were investigated in order to identify possible changes in the growth of the tissues of productive branch of the coffee tree in response to the fruit load. The effects of fruit loading were studied in four phenological stages (initial expansion, final expansion, fruit granulation and maturation), evaluating the growth of old, mature and young leaves; the section of the branches in which they are inserted, as well as the fruits. For this, manipulations in the fruit load were carried out on the whole plant cultivated in a field experiment in the region of Presidente Olegário, Minas Gerais, Brazil (18 ° 35\' 25\" S and 46° 19\' 20\'\' O; 1045 m level). The treatments consisted in reducing the loads of fruits in their initial stage of development to 0%, 30%, 60% and control maintaining 100% of the fruits in the tree. This study showed that the high fruit load mainly impairs the growth of young vegetation, but with no effect on already formed leaves and branches. It was also evidenced that the high fruit load promotes competition among the fruits affecting its size and its unit mass. This reduction of vegetative and fruit growth is mainly due to the depletion of starch in the branches that contribute strongly to the carbon supply to the sink organs. Old leaf provides sucrose to promote fruit and vegetative growth, but this carbon supply does not seem to be sufficient to maintain excess fruit growth. In this case, the starch is then consumed from the branches of these plants resulting in the increase of the sucrose content in the mature branches and leaves, which are the main responsible for allocating carbon for the growth and development of the fruits. In plants with reduced fruit load, the carbon source organs are different from plants with high fruit yield. In this case, the branch and mature leaf provide sucrose for the growth of young vegetation and fruit without apparent expense of starch accumulated in the branches. The old leaves and branches are the main immediate contributors of nitrogen, but the branches are the main source organs of this nutrient having great capacity to store nitrogen and to make it available to the plants under high yield of fruits. Thus, the nitrogen and carbon stored in the branches play a fundamental role in buffering the depletion of these nutrients caused by the excessive number of metabolic sinks. The fruits of the plants with reduced load seem to have been shaded by the abundant growth of leaves and branches of distinct form of the fruits originating from the plants with high fruit load. This shading seems to have caused a lower degree of maturation of the fruits of these plants due to the increase of phenolic compounds and reduction of pectin and anthocyanin in fruits and/or their tissues. However, this effect on fruit maturation is tenuous without altering the amount of sucrose and total soluble amino acids in the fruits and in none of the tissues that compose them. Using a metabolomic approach, it was confirmed that the organic acids were influenced by the lower degree of maturation of fruits from the plants with reduced load. This evidence also supports the idea that the higher vegetative growth of the plants with reduced load can increase the maturation time of the fruits. Analyzing the amino acid profile, it was confirmed that the old and mature leaves are the main source organs of nitrogen for the physiological sinks. The nitrogen redistribution of these leaves as asparagine, glutamine, tyrosine and phenylalanine to the drains occurred in plants with excessive fruit load. This nitrogen flow to the physiological sinks together with the protein degradation of the branches of these plants culminated with increase of phenylalanine in the grains, glutamine and aspartate in the fruits and alanine in the young leaves compared to the plants with reduced fruit load. There was stimulation of putrescine synthesis in the grains probably as a mechanism to readjust the carbon and nitrogen flux in the initially disturbed plant organism in response to the fruit load. Thus, new pre- and post-translational research needs to be developed in order to elucidate the interrelation of carbon and nitrogen metabolism to the homeostasis of its metabolites in response to fruit load.

This dissertation addresses how Paleoindians used the karst drainage of the Aucilla River in northwestern Florida during the Pleistocene/Holocene transition (approximately 15-10,000 14C yr B.P.). I take a geoarchaeological approach to discuss Paleoindian land use by first defining the Late Pleistocene and Holocene geological record, and then by creating a model of site formation processes in the Aucilla River. Both underwater and terrestrial fieldwork were performed. Underwater fieldwork consisted of hand-driven cores and surface survey, vibrocoring, underwater 1 x 1 m unit excavation, and controlled surface collection. Terrestrial fieldwork consisted of shovel and auger test pits. Seventeen cores were collected from five different submerged sinkhole sites, which were used to select two sites for further study: Sloth Hole (8JE121), which had been previously excavated, and Wayne's Sink (8JE1508/TA280), which was recorded but not formally investigated. Five vibrocores and two 1 x 1m units were used, with previous research, to define the geological and geoarchaeological context of Sloth Hole. Fifteen vibrocores, six 1 x 1 m excavation units, and ten 1 x 1 m surface collection units were used to define the geological, geoarchaeological, and archaeological context of Wayne's Sink. A combination of 130 shovel and auger test pits was used to define the geological, geoarchaeological, and archaeological potential of the terrestrial landscape. Five new Holocene-aged terrestrial sites were recorded. All of these data were evaluated with archival data from previously-excavated sites to create models of site formation and Paleoindian land use in the lower Aucilla Basin. This research shows that there have been four major periods of sinkhole infill in the lower Aucilla basin. The first occurred prior to the Last Glacial Maximum, with each sinkhole containing peat deposits that date in excess of 21,000 calendar years ago (cal B.P.). These peats are overlain by sandy colluvium that dates to approximately 14,500 cal B.P. The colluvium is overlain by clays that contain evidence for soil formation. These soils vary in age, with radiocarbon dates of approximately 14,500-10,000 cal B.P. These clays are directly overlain by peats dating to 5,000-3,500 cal B.P., which are overlain by peats and clays that date to 2,500-0 cal B.P. Intact Paleoindian and Early Archaic deposits are possible in the late Pleistocene soils.

The dynamics of natural populations may be influenced by a variety of factors, ranging from feeding interference and territoriality to the risk of predation and climatic effects. The relative influence of these factors may be contingent upon the quality of the habitat in which individuals reside. A factor that can largely affect population dynamics and that often covaries with habitat structure is predation risk. However, the combined effect of habitat and predation risk can vary according to the social context and intrinsic characteristics that affect individual behavioural responses. This thesis investigates the effects of habitat quality at the level of the population and the individual, and examines how it relates to the above factors in Siberian jays (Perisoreus infaustus), a territorial, group-living species in which the main cause of mortality is predation. The results demonstrate a strong effect of habitat on survival, reproduction and behaviour. Mortality was generally higher in open areas and managed forests and reproductive success decreased after forest management. Breeding females were more sensitive to environmental factors than males, possibly because of higher reproductive costs. Estimates of spatial demography suggested that there were more sinks than sources, and that they were located in open, managed forests. Behavioural decisions confirmed that open forests were associated with higher predation risks. However, decisions depended on social context; immigrants took highest risks and were the recipients of most aggression, largely an effect of social subordination. Also, parents provide their offspring with benefits that are withheld from immigrants. As a result, first-year survival was higher in retained offspring. Investigating the effects of multi-scale habitat quality on individual behaviour and population dynamics has generated an increased understanding of the effects of forest management on the dynamics of this population. This approach should facilitate development of an effective conservation management policy for this species.

Since most of the energy input is converted to thermal energy in laser applications, the proper thermal management of laser systems is an important issue. Maintaining the laser diode and crystal temperature distributions in a narrow range during the operation is the most crucial requirement for the cooling of a laser system. In the present study, thermoelectric cooling (TEC) of a 1064 nm wavelength diode pumped laser source is investigated both experimentally and numerically. During the heat removal process, the thermal resistance through and between the materials, the proper integration of the TEC assembly, and the heat sink efficiency become important. For the aim of evaluating and further improving the system performance, various assembly configurations, highly conductive components, efficient interface materials and heat sink alternatives are considered. Several experiments are conducted during the system development stage, and parallel numerical simulations are performed both for comparison and also for providing valuable input for the system design. Results of the experiments and the simulations agree well with each other. As the laser device works in the transient regime, the experiments and the simulations are also implemented in this regime. In the final part of the study, the experiments are performed under the actual device working conditions. It is proved that with the designed TEC module and the copper heat sink system, the laser device can operate longer than the required operational time successfully.