abstract: Single cell phenotypic heterogeneity studies reveal more information about the pathogenesis process than conventional bulk methods. Furthermore, investigation of the individual cellular response mechanism during rapid environmental changes can only be achieved at single cell level. By enabling the study of cellular morphology, a single cell three-dimensional (3D) imaging system can be used to diagnose fatal diseases, such as cancer, at an early stage. One proven method, CellCT, accomplishes 3D imaging by rotating a single cell around a fixed axis. However, some existing cell rotating mechanisms require either intricate microfabrication, and some fail to provide a suitable environment for living cells. This thesis develops a microvorterx chamber that allows living cells to be rotated by hydrodynamic alone while facilitating imaging access. In this thesis work, 1) the new chamber design was developed through numerical simulation. Simulations revealed that in order to form a microvortex in the side chamber, the ratio of the chamber opening to the channel width must be smaller than one. After comparing different chamber designs, the trapezoidal side chamber was selected because it demonstrated controllable circulation and met the imaging requirements. Microvortex properties were not sensitive to the chambers with interface angles ranging from 0.32 to 0.64. A similar trend was observed when chamber heights were larger than chamber opening. 2) Micro-particle image velocimetry was used to characterize microvortices and validate simulation results. Agreement between experimentation and simulation confirmed that numerical simulation was an effective method for chamber design. 3) Finally, cell rotation experiments were performed in the trapezoidal side chamber. The experimental results demonstrated cell rotational rates ranging from 12 to 29 rpm for regular cells. With a volumetric flow rate of 0.5 µL/s, an irregular cell rotated at a mean rate of 97 ± 3 rpm. Rotational rates can be changed by altering inlet flow rates. / Dissertation/Thesis / Video of the irregular cell rotation / M.S. Bioengineering 2011

Cette thèse présente l’analyse, la caractérisation, et l’optimisation des performances d’imageurs microbolométriques dans la gamme de fréquence sub-THz. Ce domaine non ionisant du spectre électromagnétique est en pleine expansion et la mise au point d’imageurs performants, fonctionnant à température ambiante, ouvre la voie à de nombreuses applications. Le contrôle non destructif est une de ces applications privilégiées en raison des propriétés de pénétrations de ce rayonnement au travers de nombreux matériaux, en particulier en deçà de 1 THz. Nous dressons alors à travers une analyse radiométrique en imagerie active, les performances de détection requises d’un imageur THz répondant à ce besoin.Dans ce contexte, nous avons analysé les performances électrothermiques des imageurs THz microbolométriques à l’état de l’art du CEA-LETI. Le développement d’un modèle détaillé du pont bolométrique de ces imageurs a permis de mettre en évidence les facteurs limitant leurs performances. Des voies d’améliorations ont alors été proposées dont l’intégration d’un nouveau matériau thermomètre. Les gains en performances apportés par ces optimisations ont été évalués au travers de ce modèle, démontrant que des sensibilités proches du pW sont accessibles sur ces imageurs.Un important travail expérimental a également été mené afin de déterminer les performances électromagnétiques sub-THz de la structure d’antenne de ces microbolomètres. L’accent a été mis sur la métrologie du banc expérimental développé afin de résoudre précisément les figures de mérite des dispositifs. Ces résultats de mesure ont également validé les simulations électromagnétiques de l’absorption du pixel qui ont mis en évidence un couplage avec la circuiterie du CMOS de lecture. La conséquence de ce couplage sur la qualité d’un système d’imagerie intégrant cette matrice de détection a alors été évaluée. La mesure de la Fonction de Transfert de Modulation a ainsi permis d’estimer cet impact du point de vue de la résolution du système.Afin d’améliorer les faibles rendements d’absorption de ces détecteurs, mesurés dans la gamme sub-THz, nous avons étudié l’intégration de surfaces hautes impédances au sein des pixels microbolométriques THz. Le dimensionnement de ces structures a été réalisé par la mise en œuvre de métamodèles afin d’obtenir des structures optimales en un nombre limité de simulations 3D. Des architectures de pixels associées à ces surfaces hautes impédances, réalisables sur les imageurs actuels, ont été proposées. Elles démontrent par simulation que des rendements d’absorption pics de plus de 60 % peuvent être atteint à 670 GHz malgré un pas pixel de 50 µm bien plus petit que la longueur d’onde visée. La compacité et efficacité de ces surfaces hautes impédances ont enfin été améliorées par l’utilisation d’algorithmes d’optimisation particulaires spécifiquement développés. / This PhD dissertation presents the analysis, characterization and optimization of the performances of microbolometric imagers in the sub-THz frequency range. This non ionizing span of the electromagnetic spectrum is currently a booming field of research. Development of high-performance and room temperature imagers, opens the path towards many applications. One of such promising application is non-destructive screening enabled by the good penetrating power of these radiations through many materials, especially at frequencies lower than 1 THz. Through a radiometric analysis of an active imaging system, we assess the required performances of an imager suited for this application.In this context, we have analyzed the electrothermal performances of the cutting-edge THz imagers based on microbolometer developed at CEA-Leti. Thanks to a detailed model of the bolometer bridge of these detection arrays, we have brought into focus the limiting factors of the current devices. Technological improvement have been considered such as the integration of a new thermometer material. The performance improvements brought by these optimizations have been quantified thanks to the modeling tool we have developed and it is showed that sensitivity close to the pW range can be reached on these imagers.An intensive experimental work have also been carried out in order to assess the sub-THz electromagnetic performances of the microbolometer antenna structure. Particular emphasis was placed on the metrology of the optical bench that has been built, aiming at the precise measurement of the figure of merit of the detectors. These experimental results have validated the electromagnetic simulations of the detector absorption efficiency that have exposed the coupling with the CMOS circuitry that arises at low frequencies. The consequences of this coupling on the quality of an imaging system using this detection array has been estimated. Modulation Transfer Function of the pixel has been quantified and the impact on the system resolution estimated.In order to improve the absorption efficiency of the detectors measured in the sub-THz range, we have studied the integration of high impedance surfaces within the microbolometer stack. The sizing of the high impedance surfaces has been carried out with metamodeling, leading to optimal designs with a limited number of full-wave simulations. New pixel architectures that are compatible with current imagers have been investigated. Simulations demonstrated that peak absorption efficiency higher than 60 % can be reached at 670 GHz despite a 50 µm pixel pitch, much smaller than targeted wavelength. Finally, compactness and efficiency of the high impedance surfaces have been improved by particular swarm optimization algorithm that have been specifically developed.

La problématique du vieillissement pathologique du tissu osseux (ostéoporose) est un enjeu important de santé publique. La densité minérale osseuse est considérée comme un des facteurs principaux affectant cette dégénérescence tissulaire, sans toutefois expliquer complètement le risque fracturaire. L’accumulation du micro-endommagement en lien avec cette pathologie présente un nouvel angle d’investigation intéressant. Dans ce contexte, une méthode d’acousto-élasticité dynamique (DAET) associant une onde acoustique basse fréquence et des impulsions ultrasonores a été développée au laboratoire pour la quantification du micro-endommagement dans l’os trabéculaire. La DAET permet de mesurer les non-linéarités élastiques et dissipatives, respectivement associées aux variations de temps de vol et d’amplitude des impulsions pour différents états de contrainte basse fréquence auxquels est soumis le tissu osseux.Ce travail a consisté à étudier la sensibilité et la reproductibilité de l’approche DAET à détecter/quantifier in vitro le niveau de micro-endommagement -natif ou induit mécaniquement par fatigue en compression- dans des échantillons osseux trabéculaires issus de calcanéums humains. De forts niveaux de non-linéarités acoustiques ont toujours été corrélés à une densité de micro-endommagements importante (analyse histologique). La présence de microbulles d’air (fortement non linéaires) et l’apparition d’un phénomène de conditionnement des échantillons par l’onde acoustique basse-fréquence ont tempéré la reproductibilité de l’approche DAET. Cette difficulté ne remet toutefois pas en cause la pertinence de cette méthode dans le cadre d’une application in vivo de la mesure DAET. / Bone tissue pathological aging (osteoporosis) is an important public health issue. Bone mineral density (BMD) is considered as a major factor of the bone tissue strength, but does not fully explain the fracture risk. The accumulation of microdamage in connection with this disease open up an interesting perspective of investigation. In this context, a dynamic acoustoelastic testing (DAET) method associating a low frequency acoustic wave and ultrasonic pulses was developed in the laboratory to quantify microdamage in trabecular bone.The purpose of this work was to assess the sensitivity and the reproducibility of the DAET approach to monitor in vitro (either native or mechanically induced fatigue) microdamagein trabecular samples extracted from human calcanei.High levels of acoustic nonlinearities were always correlated with a high density of microdamage (histological analysis). Nevertheless, the presence of highly nonlinear air bubbles and conditioning effects induced by the low-frequency wave moderated the DAET reproducibility.This difficulty, however, does not question the relevance of this method for in vivo DAET application.

Previous academic research which focused on girls’ behaviour tended to do so by looking at behaviour in terms of the extremes: by either exploring the perceptions and experiences of girls who appear to behave well, or alternatively, by researching girls who are categorised as extreme misbehavers, in institutions such as Pupil Referral Units. This ethnographic study was undertaken in a state secondary school setting over one academic year. The research centred on girls who were in Years 10 and 11, and is an exploration of the micro performances of their behaviour in the school. The ethnographic nature of the research allowed an in depth focus on girls’ micro performances in school. The feminist influenced thesis seeks to explore girls’ constructions of gender, how this is negotiated alongside their wider performances as pupils in the school and is subsequently recognised (by themselves and others), as performances of particular behaviour. The research draws on Goffman’s (1959) conceptualisation of performance and impression management, Butler (1990), theoretical notions of performativity and Foucault’s (19757:1978) theories of power, discourse and surveillance, to explore how gender and behaviour are being understood in this context. The study sought to explore the world from the girls’ viewpoint to understand the complexity of their experiences more fully. The research examines not only how the girls were positioned in terms of their perceived behaviour, but also how they responded to this positioning (their resistance and accommodation of these positions, and the shifting nature of these positionings across time) and how these were often perceived in relation to particular gendered expectations. The originality of the research stems from findings about issues of self-harm, panic attacks, authenticity, social media, middle class girls and fighting, which lie in the rich and detailed empirical data arising from the study. The significance of these findings draws these multiple threads together, giving insight into gender positioning and behaviour, and the study privileges the girls’ voices as they discuss their feelings and the effects of these issues on them, complicating previous research.

En la actualidad, el sector eléctrico chileno se caracteriza por contar con una demanda creciente y un perfil de expansión descentralizado lo cual ha generado nuevas oportunidades en el segmento de generación, siendo una de ellas la generación distribuida y, en particular, la micro generación. Por otra parte, se aprecia tanto a nivel mundial como local una mayor preocupación hacia la problemática ambiental, lo que sumado a problemas de abastecimiento de algunos energéticos primarios, ha incentivado el desarrollo tecnológico de diversas formas de generación eléctrica en base a energías renovables. El objetivo principal del presente trabajo de título es estudiar la factibilidad técnica y normativa de la incorporación de micro generación basada en energías renovables en redes de distribución urbanas de baja tensión, incorporando distintas tecnologías de generación y analizando distintos escenarios de penetración de micro generación. Lo anterior se lleva a cabo a través de simulaciones estáticas y dinámicas de la conexión de unidades a un alimentador de baja tensión tipo. La metodología utilizada para el desarrollo de este trabajo se compone de tres etapas: en la primera, se analiza el estado actual de los aspectos relevantes a considerar tales como tecnologías de micro generación y la normativa vigente. En la segunda etapa, se realiza un modelamiento a escala de las unidades de micro generación y se construye un alimentador de baja tensión tipo para un sector residencial. Por último, en la tercera etapa se realizan simulaciones de la conexión de micro generación con distintos niveles de penetración considerando dos escenarios de demanda y perfiles de generación obtenidos a partir de la disponibilidad de los energéticos primarios en cada escenario. Se observa que las tecnologías de micro generación están en una etapa de madurez y confiabilidad apta para aplicaciones en baja tensión, siendo las principales barreras para su incorporación los altos costos, la falta de información y carencia de herramientas regulatorias. Los efectos derivados de la conexión que se observan en la red de baja tensión permiten concluir que no existen dificultades técnicas mayores para la conexión de micro generación, obteniendo efectos indeseados para niveles de penetración superiores al 50%, nivel para el cual se hace altamente recomendable considerar un cambio en el esquema de protecciones de la red e incorporación de filtros para evitar contaminación armónica. Así mismo, se comprueba que la instalación de micro generación no sólo colabora a objetivos de suministro y disminución de emisión de contaminantes, sino que puede mejorar las características de la red como por ejemplo el perfil de tensiones a lo largo del alimentador, provocando una mejor calidad de suministro.

En la problemática de abastecer de energía eléctrica a una localidad aislada, ha ido tomando fuerza el desarrollo de las llamadas micro-redes. Estas soluciones consisten en sistemas eléctricos pequeños, que cuentan con generadores de baja potencia nominal que abastecen consumos físicamente cercanos. Una ventaja que ofrecen las micro-redes frente a sistemas mayores viene justamente de esta proximidad entre generación y consumos, minimizando las pérdidas en las líneas. Sin embargo, la calidad de suministro tiende a ser menor debido a que no e factible aprovechar las ventajas de los sistemas interconectados: inercia, respaldo, diversidad de fuentes. De esta forma, es clave el desarrollo de esquemas de control adecuados que permitan asegurar niveles mínimos de calidad de suministro. Un elemento central de estos esquemas de control es su capacidad para determinar en forma confiable el estado del sistema eléctrico a partir de un número limitado de medidas de fácil adquisición. En este contexto, el objetivo de este trabajo de memoria es disponer de un modelo de estimación de estado para micro-redes, a través de un proceso de análisis, diseño e implementación a escala prototipo. La herramienta resultante debe ser capaz de analizar la micro-red del pueblo de Huatacondo, un pueblo al norte de Chile cuyo suministro eléctrico proviene en gran medida de fuentes de energía renovables no convencionales, como aplicación práctica. Asimismo, debe proyectarse como herramienta docente, para la estimación de estado de la micro-red del Laboratorio de Energía y Accionamientos del Departamento de Ingeniería Eléctrica de la Universidad de Chile. El modelo estimador de estado que se desarrolla se basa en el método clásico de Mínimos Cuadrados Ponderados, que permite estimar la tensión fasorial en las barras de una micro-red, dando más importancia a las medidas más precisas entre las que se dispone. Las medidas que se consideran en este trabajo son módulos de tensiones, flujos de potencia activa y reactiva en líneas y potencia activa y reactiva en ciertas barras de consumo o generación. Se valida el funcionamiento del estimador de estado desarrollado mediante ejemplos disponible en la literatura especializada, con errores en torno a la tolerancia de 1,35%. Asimismo, se identifica un caso anómalo descrito en la literatura. Sin embargo, en este caso la convergencia del algoritmo si bien detecta la medición errónea, lo reporta a través de una solución no factible en términos físicos. Se ejecuta la aplicación diseñada en la micro-red del laboratorio y en la de Huatacondo, comparando las potencias calculadas a partir del estado encontrado con las potencias medidas, obteniéndose un error relativo porcentual promedio cercano al 2% en el caso del laboratorio y del 0,2% en el caso de Huatacondo. Dado esto, se concluye que la aplicación diseñada cumple el objetivo de obtener el estado de la micro-red de manera confiable. Cabe señalar que en el caso de la estimación de los ángulos de fase de las tensiones, la verificación en el laboratorio a través de mediciones obtuvo resultados con errores mayores. Estas diferencias pueden explicarse por errores en las mediciones o en los parámetros del sistema. Como trabajo futuro, se propone el desarrollo de la etapa de control que mantenga al sistema en el estado de operación normal, el estudio y comparación con otros modelos de estimación de estado y la integración del programa construido con la aplicación Deep-Edit desarrollada en el Departamento.

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-26T13:36:53Z No. of bitstreams: 1 Dissertação_05082015.pdf: 7513820 bytes, checksum: 7fe5312c34982c2ea718e8ed9e79d68d (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-26T14:35:29Z (GMT) No. of bitstreams: 1 Dissertação_05082015.pdf: 7513820 bytes, checksum: 7fe5312c34982c2ea718e8ed9e79d68d (MD5) / Made available in DSpace on 2016-09-26T14:35:29Z (GMT). No. of bitstreams: 1 Dissertação_05082015.pdf: 7513820 bytes, checksum: 7fe5312c34982c2ea718e8ed9e79d68d (MD5) / Nesse trabalho foram estudadas e desenvolvidas novas metodologias para síntese de N-heterociclos de cinco membros, 2-pirrolidinonas, através da aplicação da reação de cicloadição formal aza-[3+2]; A metodologia aplicada foi pautada nos princípios da química verde, como: reações sem solvente, uso de catalisadores de bismuto, aplicação de radiação de micro-ondas, levando à construção de 2- pirrolidinonas N-substituídas com substituintes retiradores e doadores de elétrons. A metodologia de catalise por bismuto foi estendida para a síntese de biciclos do tipo pirrolizidínicos, produzindo-os em uma faixa menor de tempo, núcleo presente em muitos alcaloides já conhecidos por sua toxicidade e aplicação como fármacos. Estudos com programas de bioinformática foram realizados para predição das propriedades biológicas das moléculas sintetizadas / In this work has been studied and developed new ways to synthetize five- membered N-heterocycles, 2-pyrrolidinones, through the application of a formal cycloaddition aza-[3+2] reaction. The methodology applied was based on green chemistry principles: solvent less, the use of bismuth catalyst, applying microwaves radiation, which allowed the construction of 2-pyrrolidinones electrodonating and withdrawing substituents. This method of catalysis bismuth was extended to the synthesis of the bicycle pyrrolizidine type, producing them on a smaller time range, this nucleus have been present in too many natural alkaloids known for used as pharmaceuticals. Studies with bioinformatics programs were performed to predict the biological properties of the synthesized molecules.

Submitted by Diana Alves (ppgdancaufba.adm@gmail.com) on 2013-02-26T11:59:01Z No. of bitstreams: 1 Dissertação Final.pdf: 914537 bytes, checksum: c6ca4a4ef5afa40710459df1bb1eb41f (MD5) / Approved for entry into archive by Alda Lima da Silva(sivalda@ufba.br) on 2013-02-26T17:28:19Z (GMT) No. of bitstreams: 1 Dissertação Final.pdf: 914537 bytes, checksum: c6ca4a4ef5afa40710459df1bb1eb41f (MD5) / Made available in DSpace on 2013-02-26T17:28:19Z (GMT). No. of bitstreams: 1 Dissertação Final.pdf: 914537 bytes, checksum: c6ca4a4ef5afa40710459df1bb1eb41f (MD5) / CAPES / A História da Dança é o campo de pesquisa responsável pelo estudo das narrativas históricas e pela memória desta linguagem artística. A presente pesquisa vem propor uma reflexão sobre os aspectos da produção brasileira da historiográfica da Dança, sobretudo aquelas publicações e novos ambientes de produção e disseminação, surgidos e consolidados entre os anos de 2001 e 2011. Alguns conceitos e reflexões de historiadores ligados ao movimento francês da Nova História (Peter Burke, Carlo Ginzburg, Jacques Le Goff, Marc Bloch, entre outros) embasam e argumentam as perspectivas apontadas nesta dissertação, justificando e apontando outros olhares para a prática de pesquisa acadêmica em História da Dança. Portanto, o objetivo principal destas reflexões é levantar questionamentos e ampliar as discussões acerca dos aspectos referentes às práticas historiográficas para a Dança, desenvolvidas no Brasil, incluído sua produção bibliográfica. / Programa de Pós Graduação em Dança-Escola de Dança

136f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-03-06T16:11:19Z No. of bitstreams: 1 Amilton%20Reisseg.pdf: 677748 bytes, checksum: 54c2d1d1e6da5d158561f70d1111afa0 (MD5) / Approved for entry into archive by Vania Magalhaes(magal@ufba.br) on 2013-03-14T12:28:10Z (GMT) No. of bitstreams: 1 Amilton%20Reisseg.pdf: 677748 bytes, checksum: 54c2d1d1e6da5d158561f70d1111afa0 (MD5) / Made available in DSpace on 2013-03-14T12:28:10Z (GMT). No. of bitstreams: 1 Amilton%20Reisseg.pdf: 677748 bytes, checksum: 54c2d1d1e6da5d158561f70d1111afa0 (MD5) Previous issue date: 2007 / Esta dissertação visa analisar o atendimento à demanda de crédito das micro e pequenas empresas (MPEs) por parte do sistema bancário, enfatizando as peculiaridades do mercado brasileiro, com o objetivo de identificar em que medida o caso particular brasileiro se aproxima ou se afasta do padrão geral apresentado no resto do mundo. Parte-se dos conceitos expostos por Marx sobre o desenvolvimento do sistema de crédito, demonstrando a sua importância fundamental no processo de reprodução do capital. Posteriormente, a partir da constatação de que as MPEs não têm sua demanda por crédito bancário plenamente atendida, e, mais ainda, constatado que a oferta de crédito para essas empresas é efetivamente racionada, parte-se para uma revisão das principais teorias que tratam da estrutura de capitais de empresas, com o propósito de verificar suas aderências ou contradições com a imposição teórica da necessidade de circulação de capitais via sistema de crédito para a sobrevivência do capitalismo. Para juntar as duas extremidades, encontrou-se como elo os estudos efetuados sobre assimetria de informações e outras imperfeições do mercado de crédito, cujas evidências confirmam e dão sentido aos pressupostos teóricos tomados como ponto de partida. Na análise do caso brasileiro, procurou-se identificar os pontos comuns com o padrão internacional de oferta de crédito às MPEs e evidenciar os aspectos peculiares do caso brasileiro, o qual, pelas nuances do desenvolvimento do seu sistema bancário, ainda remonta a um passado recente. / Salvador

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2017-05-17T12:13:37Z No. of bitstreams: 1 texto completo.pdf: 1732607 bytes, checksum: 17fd4bd61d72d0dd64ab43b1b834f386 (MD5) / Made available in DSpace on 2017-05-17T12:13:37Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1732607 bytes, checksum: 17fd4bd61d72d0dd64ab43b1b834f386 (MD5) Previous issue date: 2012-09-25 / O eucalipto ocupa posição de destaque no setor florestal brasileiro em razão do rápido crescimento e adaptabilidade às diversas condições edafoclimáticas e das características tecnológicas da madeira. Entretanto, as respostas da planta à adição de nitrogenados em florestas continuam sucitando questionamentos. A estratégia de estudo considerando o balanço energético do sistema solo-planta pela existência de um “nitrostato” que controla as entradas e saídas do nitrogênio representa modelo a ser validado para otimizar a produtividade com economia na fertilização nitrogenada em florestas da região tropical. Assim, o presente trabalho teve como objetivo determinar a influência da interrupção do fluxo de fotoassimilados da parte aérea para a rizosfera pelo anelamento de árvores sobre a estrutura da comunidade microbiana do solo e nitrogênio mineral. O estudo foi conduzido em duas fases de crescimento pós-plantio em florestas de eucalipto na região do Vale do Rio Doce, Minas Gerais, Brasil, áreas sob domínio do Bioma Mata Atlântica. Os maiores teores de carbono orgânico total do solo, 3,95 dag kg -1 em floresta com 18 meses de desenvolvimento pós-plantio e 3,62 dag kg -1 na com 72 meses, ocorreram no período chuvoso. Os teores de NH 4+ em torno de 27 mg kg -1 de solo seco, e os de NO 3- em torno de 40 mg kg -1 de solo seco, foram maiores durante os períodos úmidos e correspondentes a aproximadamente duas vezes os valores do período seco. Já valores de respiração no solo foram maiores na época seca. O índice de diversidade de Shanon (H) variou de 1,7 a 3,5 considerando os domínios, Bacteria, Archaea e Eukarya nas duas fases de crescimento pós-plantio e mostrou que a fase de crescimento não afetou a diversidade microbiana. A avaliação dos perfis de eletroforese em gel com gradiente desnaturante (DGGE) revelou pelo método de agrupamento médio entre grupos (UPGMA) a tendência de agrupamento dos perfís das amostras coletadas na rizosfera, donde se inferiu a existência de capacidade da planta de moldar a estrutura da comunidade microbina na rizosfera e rizoplano. A variação dos perfis de DGGE dentro de gradiente sazonal mostrou que o aporte de fotoassimililados para a rizosfera e a umidade determinam a estrutura da comunidade microbiana em solos sob florestas plantadas de eucalipto. / Eucalyptus are fast growing woody plants with the ability to adapt when exposed to different edaphoclimatics conditions and with woody technological characteristics that make them important players in the brazilian forest sector. However, the plant responses to the nitrogen additions continue raising questions. The strategy of study considering the soil-plant energetic balance by the existence of a nitrostat represents a model to be validated in order to optimize the productivity by saving in the nitrogen fertilization in tropical forests. This work aimed to evaluate the effect of the photoassimilates flow from aerial part of the plants by girdling the eucalyptus trees in the soil microbial community structure and in the mineral nitrogen. The study was performed in two distinct growth stages of two post-planting growth stage in Eucalyptus forests in the Vale do Rio Doce area, Minas Gerais state, Brazil, dominated by Atlantic Forest biome. The highest total organic carbon content, 3.95 dag kg-1 in forests with 18 months of post- planting development and 3.62 dag kg-1 in those with 72 months, were found during the rainy season. The NH4+ content around 27 mg kg-1 in the dry soil, and the N03+ content around 40 mg kg-1, were higher during the wet season and about twice the amount found during the dry season. The Shanon (H)diversity index ranged from 1.7 to 3.5 considering the Bacteria, Archaea and Eukarya domains and showed no effect of growth stage in the microbial diversity. Clustering analysis by the method of Unweighted Pair Group Method with Arithmetic Mean (UPGMA) of the Denaturing Gradient Gel Electrophoresis (DGGE) profiles revealed that samples from rhizosphere grouped together, showing that plants have the ability to recruit a specific microbial community in the rhizosphere and in the rhizoplane. Changes in the DGGE profiles within a seasonal gradient point out that the input of photoassimilates to the rhizosphere and the moisture determine the microbial community structure in soil under Eucalyptus forests. / Resumo em inglês do arquivo PDF difere da versão impressa. Resumo em inglês do PDF foi substituído pelo resumo em inglês escaneado da versão impressa. Foi enviada somente 1 (uma) cópia da versão impressa pela Secretaria do curso.