Um resultado clássico em Geometria Diferencial, conhecido como teorema de Hadamard, e demonstrado pelo mesmo ([Ha]), estabelece que uma superfície conexa compacta no espaço Euclidiano cujas curvaturas principais são todas positivas é o bordo de um corpo convexo. Em part icular, a superfície é difeomorfa a uma esfera. Neste trabalho apresentamos extensões parciais deste teorema para imersões de codimensão arbitrária e para outros espaços ambientes que o E uclidiano conforme feito em [R]. / A classical result in differential geometry, known as Hadamard's theorem and proved by himself ([Ha]). establishes that a compact connected surface in the Euclidean space whose principal curvatures are everywhere positive is the boundary of a convex body. In particular, the surface is diffeomorphic to a sphere. In this work we present IJartial extensions of this theorem to immersions of arbitrary codimension and to other spaces than the Euclidean one, as clone in [R].

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-02-05T22:23:13Z No. of bitstreams: 1 LeonardoResende_DISSERT.pdf: 7377959 bytes, checksum: 16ea1cdbf54927d2b45fc0aac9163621 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-02-16T00:06:40Z (GMT) No. of bitstreams: 1 LeonardoResende_DISSERT.pdf: 7377959 bytes, checksum: 16ea1cdbf54927d2b45fc0aac9163621 (MD5) / Made available in DSpace on 2016-02-16T00:06:40Z (GMT). No. of bitstreams: 1 LeonardoResende_DISSERT.pdf: 7377959 bytes, checksum: 16ea1cdbf54927d2b45fc0aac9163621 (MD5) Previous issue date: 2014-09-24 / Do ponto de vista econ?mico, a metalurgia do p? (MP) ? uma t?cnica bastante usada para a produ??o de pe?as de pequeno porte. ? poss?vel, atrav?s da MP e de uma pr?via cominui??o de res?duos s?lidos tais como cavacos ferrosos, produzir pe?as sinterizadas altamente densas e de interesse para a ind?stria automotiva, eletr?nica e aeroespacial. No entanto, sem essa pr?via cominui??o dos cavacos, a produ??o de corpos com densidade igual a densidade te?rica por t?cnicas convencionais de sinteriza??o necessitaria do uso de aditivos ou de temperaturas significativamente maiores do que 1250?C. Uma rota alternativa para a fabrica??o de corpos sinterizados com alta densidade a partir de compacta??o de cavacos ferrosos (? 850 ?m) e sinteriza??o em fase s?lida ? a t?cnica de compacta??o sob alta press?o (AP). Nesse trabalho, foram usadas diferentes press?es de compacta??o para a produ??o de sinterizados de cavacos de a?o carbono SAE 1050. Especificamente, foi investigado o efeito da alta press?o de compacta??o no comportamento da densifica??o das amostras sinterizadas. Portanto, amostras de cavacos do a?o carbono SAE 1050 foram compactadas uniaxialmente a frio sob press?es de 500 e 2000 MPa, respectivamente. Os corpos verdes obtidos foram sinterizados sob atmosfera carbonetante a 1100 e 1200?C por 90 minutos. A taxa de aquecimento usada foi de 20?C/min. Os materiais de partida e os corpos sinterizados foram caracterizados por microscopia ?ptica, MEV, DRX, medidas de densidade (geom?trica: massa/volume, e picnometria) e medidas de microdureza Vickers e dureza Rockwel. Os resultados obtidos mostraram que os compactos produzidos sob 2000 MPa apresentaram valores de densidade relativa de 93% a 100% da densidade te?rica e microdureza entre 150 HV e 180 HV, respectivamente. Diferentemente, os compactados sob 500 MPa apresentaram uma microestrutura bastante heterog?nea, valor de densidade abaixo de 80% da densidade te?rica e condi??es estruturais das amostras inadequadas para a realiza??o das medidas de microdureza e dureza. Os resultados obtidos indicam que utiliza??o da compacta??o sob alta press?o de cavacos ferrosos ? uma rota bastante promissora para melhorar as condi??es de sinterabilidade deste tipo de material, pois, al?m de promover uma maior compacta??o do material de partida, a tens?o externa atua, juntamente com a tens?o superficial, funcionando como for?a motriz para o processo de sinteriza??o. Adicionalmente, press?es extremamente elevadas permitem a deforma??o pl?stica dos materiais, promovendo um contato ?ntimo e extenso das part?culas e eliminando poros e trincas. Isso tende a diminuir o tempo e/ou a temperatura necess?rias para uma boa sinteriza??o, evitando-se o crescimento excessivo de gr?os, sem o uso de aditivos. Al?m disso, as press?es elevadas provocam fratura nos gr?os em materiais fr?geis ou d?cteis altamente encruados, o que propicia um p? de partida, para a sinteriza??o, mais fino, sem os riscos de contamina??o presentes quando s?o usados m?todos de cominui??o pr?via do p?. / From an economic standpoint, the powder metallurgy (P/M) is a technique widely used for the production of small parts. It is possible, through the P/M and prior comminution of solid waste such as ferrous chips, produce highly dense sintered parts and of interest to the automotive, electronics and aerospace industries. However, without prior comminution the chip, the production of bodies with a density equal to theoretical density by conventional sintering techniques require the use of additives or significantly higher temperatures than 1250?C. An alternative route to the production of sintered bodies with high density compaction from ferrous chips (? 850 microns) and solid phase sintering is a compression technique under high pressure (HP). In this work, different compaction pressures to produce a sintered chip of SAE 1050 carbon steel were used. Specifically, the objective was to investigate them, the effect of high pressure compression in the behavior of densification of the sintered samples. Therefore, samples of the chips from the SAE 1050 carbon steel were uniaxially cold compacted at 500 and 2000 MPa, respectively. The green compacts obtained were sintered under carbon atmosphere at 1100 and 1200?C for 90 minutes. The heating rate used was 20?C/min. The starting materials and the sintered bodies were characterized by optical microscopy, SEM, XRD, density measurements (geometric: mass/volume, and pycnometry) and microhardness measurements Vickers and Rockwell hardness. The results showed that the compact produced under 2000 MPa presented relative density values between 93% and 100% of theoretical density and microhardness between 150 HV and 180 HV, respectively. In contrast, compressed under 500 MPa showed a very heterogeneous microstructure, density value below 80% of theoretical density and structural conditions of inadequate specimens for carrying out the hardness and microhardness measurements. The results indicate that use of the high pressure of ferrous chips compression is a promising route to improve the sinterability conditions of this type of material, because in addition to promoting greater compression of the starting material, the external tension acts together with surface tension, functioning as the motive power for sintering process. Additionally, extremely high pressures allow plastic deformation of the material, providing an intimate and extended contact of the particles and eliminating cracks and pores. This tends to reduce the time and / or temperature required for good sintering, avoiding excessive grain growth without the use of additives. Moreover, higher pressures lead to fracture the grains in fragile or ductile materials highly hardened, which provides a starting powder for sintering, thinner, without the risk of contamination present when previous methods are used comminution of the powder.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-03-22T00:17:59Z No. of bitstreams: 1 GilbertoMelchiors_TESE.pdf: 68131058 bytes, checksum: 5c5b863430fd078b972416d9cc3742d6 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-03-22T21:40:15Z (GMT) No. of bitstreams: 1 GilbertoMelchiors_TESE.pdf: 68131058 bytes, checksum: 5c5b863430fd078b972416d9cc3742d6 (MD5) / Made available in DSpace on 2016-03-22T21:40:15Z (GMT). No. of bitstreams: 1 GilbertoMelchiors_TESE.pdf: 68131058 bytes, checksum: 5c5b863430fd078b972416d9cc3742d6 (MD5) Previous issue date: 2015-03-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / As pseudoligas Nb-Cu apresentam-se como potenciais substitutas ?s ligas de um sistema conhecido e j? aplicado comercialmente, como as de W-Cu, usadas em aplica??es como dissipadores de calor, contatos el?tricos e bobinas para gera??o de altos campos magn?ticos. Por tratar-se de um sistema imisc?vel, onde h? insolubilidade m?tua e baixa molhabilidade do Cu l?quido na superf?cie do Nb, a rota de processamento empregada neste trabalho foi a da Metalurgia do P?. Duas composi??es de Nb foram utilizadas, com adi??es de 10% e 20% em peso de Cu, e tempos de 20, 30 e 40 horas, para a moagem de alta energia dos p?s de partida. A evolu??o da moagem dos p?s ? apresentada atrav?s de diversas t?cnicas de caracteriza??o, como a particulometria por difra??o a LASER, DRX, MEV, EDS, DSC, dilatometria, MET e an?lise qu?mica. Ap?s a moagem, partes das cargas de p?s foram submetidas ao tratamento t?rmico de recozimento. O processo empregado para a consolida??o das amostras foi a compacta??o a quente, a qual foi aplicada tanto em algumas amostras de p?s mo?dos, quanto nos p?s recozidos. Tratamentos t?rmicos posteriores foram realizados nas amostras, nas temperaturas de 1000?C (em fase s?lida) e 1100?C (em fase l?quida do Cu). Todos os conjuntos de amostras consolidadas e tamb?m os dois conjuntos das tratadas termicamente foram analisados por DRX, MEV, EDS, densidade e microdureza Vickers. Paralelamente, outras amostras de p?s de Nb com 10% e 20% em peso de Cu obtidas por simples mistura mec?nica, foram consolidadas, tratadas termicamente e caracterizadas com as mesmas t?cnicas aplicadas nas demais, e os resultados foram comparados entre eles. Apesar da dificuldade de consolida??o e densifica??o das duas pseudoligas do sistema Nb-Cu deste estudo, na rota que passa pela MAE, foram obtidas amostras com densidades em torno de 90% da densidade te?rica. E, na rota de processamento das amostras que foram apenas misturadas, os valores chegaram at? 97%. Por isso, nesse trabalho, tamb?m s?o enfatizados os processos que tornaram poss?veis os resultados encontrados. / The Nb-Cu pseudoalloys present themselves as potential substitutes for the alloys from a well known system and already commercially applied, as the W-Cu alloys, used in applications such as heat sinks, electrical contacts and coils for the generation of high magnetic fields. Because it is an immiscible system, where there is mutual insolubility and low wettability of the liquid Cu on the Nb surface, the processing route used in this work was the Powder Metallurgy. Two Nb alloys were used, with additions of 10% and 20% in weight of Cu, and times of 20, 30 and 40 hours for the high energy milling of the starting powders. The milling evolution of the powders is presented through the characterization techniques, such as the LASER diffraction for particle size, XRD, SEM, EDS, DSC, dilatometry, TEM and chemical analysis. After the milling, portions of the loads were submitted to the annealing heat treatment. The process used for the samples consolidation was the hot pressing, which has been applied both on some milled powders samples, as on the annealed powders. Subsequent heat treatments were performed in the samples at temperatures of 1000?C (solid phase) and 1100?C (in the Cu liquid phase). All sets of consolidated samples, and also the two sets of the heat treated, were analyzed by XRD, SEM, EDS, density and Vickers microhardness. Moreover, other Nb powder samples with 10% and 20% in weight of Cu obtained by simple mechanical mixing, were consolidated, thermally treated and characterized with the same techniques applied to the others, and the results were compared among themselves. Despite the difficulty of consolidation and densification of the two pseudoalloys of the Nb-Cu system of this study, on the route that passes through the HEM, samples were obtained with densities around 90% of the theoretical density. And, on the processing route of which were only mixed, the values reached up to 97%. Therefore, in this work are also emphasized the processes that made possible these results.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-04-08T23:56:19Z No. of bitstreams: 1 JoseRodolfoLopesDePaivaCavalcanti_TESE.pdf: 2156602 bytes, checksum: 000c3eafedc8a66a1a55425b0168fd4a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-11T23:46:45Z (GMT) No. of bitstreams: 1 JoseRodolfoLopesDePaivaCavalcanti_TESE.pdf: 2156602 bytes, checksum: 000c3eafedc8a66a1a55425b0168fd4a (MD5) / Made available in DSpace on 2016-04-11T23:46:45Z (GMT). No. of bitstreams: 1 JoseRodolfoLopesDePaivaCavalcanti_TESE.pdf: 2156602 bytes, checksum: 000c3eafedc8a66a1a55425b0168fd4a (MD5) Previous issue date: 2015-04-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Sabe-se que o grupo das catecolaminas ? integrado pela dopamina, noradrenalina e adrenalina e que a s?ntese dessas subst?ncias se d? de modo sequencial, sendo a enzima tirosina-hidroxilase reguladora da fase inicial deste processo. Neste sentido, a 3- hidroxitiramina/dopamina ? precursora da s?ntese de noradrenalina e adrenalina e ainda possui a capacidade de atuar como neurotransmissor na por??o central do sistema nervoso. Os tr?s principais n?cleos dopamin?rgicos, chamados zona retrorubral (grupo A8), subst?ncia negra pars compacta (grupo A9) e ?rea tegmentar ventral (grupo A10), est?o dispostos na por??o die-mesencef?lica e est?o envolvidos em tr?s vias, a mesostriatal, mesol?mbica e mesocortical. Estas vias est?o relacionadas diretamente com diversas manifesta??es comportamentais como controle da motricidade, sinaliza??o de recompensa na aprendizagem comportamental, motiva??o e nas manifesta??es patol?gicas da Doen?a de Parkinson e esquizofrenia. Considerando-se a relev?ncia desses, o objetivo do trabalho foi caracterizar morfologicamente os n?cleos dopamin?rgicos (A8, A9 e A10) do sagui (Callithrix jacchus) mediante estudo citoarquitet?nico e imunoistoqu?mico contra tirosina-hidroxilase. O sag?i ? um primata neotropical, cujas caracter?sticas morfofuncionais repercutem na adequabilidade de uso deste animal em pesquisas de ordem biom?dica. Sec??es coronais dos enc?falos de seis animais foram submetidas ? colora??o pelo m?todo de Nissl e immunoistoqu?mica para tirosinsa-hidroxilase. Com base na morfologia dos neur?nios, foi poss?vel subdividir o grupo A10 em sete regi?es: n?cleo interfascicular, linear rostral e linear caudal, situados na linha m?dia; paranigral e o parainterfascicular, situados na zona intermedi?ria; a por??o rostral da ?rea tegmentar ventral e o n?cleo parabraquial pigmentado, situados na por??o dorsolateral do tegmento mesencef?lico. O grupo A9 foi subdividido em quatro regi?es: subst?ncia negra camadas dorsal e ventral; subst?ncia negra conjuntos lateral e medial. Por ?ltimo, n?o foram indentificadas subdivis?es no grupo A8. Conclu?-se que A8, A9 e A10 s?o filogeneticamente conservados entre as esp?cies, por?m percebe-se a necessidade de se ampliar os estudos acerca das organiza??es subnucleares, seja investigando a sua ocorr?ncia em outras esp?cies de primatas, seja investigando a sua relev?ncia funcional. / It is known that the catecholamine group is constituted by dopamine, noradrenaline and adrenaline, in which the synthesis is regulated by an enzyme named tyrosine hydroxylase. Thus, 3-hydroxytyramine/dopamine (DA) is a precursor of the noradrenaline and adrenaline synthesis and acts as a neurotransmitter in the central nervous system. The three main nuclei, named the retrorubral field (A8 group), the substantia nigra pars compacta (A9 group) and the ventral tegmental area (A10 group), are arranged in the die-mesencephalic portion and are involved in three complexes circuitries - the mesostriatal, mesolimbic and mesocortical pathways. These pathways are related to behavioral manifestations, motricity, learning, reward and pathologies such as Parkinson?s Disease and Schizophrenia. Thus, the aim of this study was to perform de morphological analysis of the A8, A9 and A10 nuclei of the common marmoset (Callithrix jacchus). The marmoset is a neotropical primate, whose morphological and functional characteristics supports the suitability of use of this animal in biomedical research. Coronal sections of the marmoset brain were submitted to cytoarchitectonic characterization and TH-immunohistochemistry. Based on the morphology of the neurons, it was possible to subdivide the A10 group in seven regions: interfascicular nucleus, raphe rostral linear nucleus and raphe caudal linear nucleus, in the middle line; paranigral and parainterfascicular nucleus, in the middle zone; rostral portion of the ventral tegmental area nucleus and parabrachial pigmented nucleus, located in the dorsolateral portion of the mesencephalic tegmentum. A9 group was divided into four regions: substantia nigra compacta dorsal and ventral tiers; substantia nigra compacta lateral and medial clusters. No subdivisions were founded into A8 group. These results revealed that A8, A9 and A10 are phylogenetically conserved between species, but it?s necessary to expand the studies about this compartmentalization, investigating its occurrence in other primate species or investigating its functional relevance.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-01-12T14:20:00Z No. of bitstreams: 1 RodolfoAlbuquerqueBuarqueDeAssuncao_DISSERT.pdf: 3341925 bytes, checksum: 95332904ffdde1cc83db64f825ee63fe (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-01-18T14:22:16Z (GMT) No. of bitstreams: 1 RodolfoAlbuquerqueBuarqueDeAssuncao_DISSERT.pdf: 3341925 bytes, checksum: 95332904ffdde1cc83db64f825ee63fe (MD5) / Made available in DSpace on 2017-01-18T14:22:16Z (GMT). No. of bitstreams: 1 RodolfoAlbuquerqueBuarqueDeAssuncao_DISSERT.pdf: 3341925 bytes, checksum: 95332904ffdde1cc83db64f825ee63fe (MD5) Previous issue date: 2016-06-30 / O comp?sito Mo-Cu ? muito usado como material para contatos el?tricos e dissipadores de calor devido ?s excelentes propriedades do cobre de condutividade t?rmica e el?trica e boa trabalhabilidade, aliada ? alta resist?ncia a solda e eros?o por arco el?trico do molibd?nio. No primeiro caso, formas bastante simples s?o exigidas e a infiltra??o de cobre l?quido em um esqueleto de molibd?nio pr?-sinterizado ? a t?cnica de consolida??o normalmente utilizada. Diferentemente, geometrias mais complexas e densidades iguais ou pr?ximas da te?rica s?o necess?rias para aplica??o como dissipadores de calor. A metalurgia do p? atrav?s das t?cnicas de prepara??o de p?s com processamento por moagem de alta energia, compacta??o ou moldagem de p? por inje??o e sinteriza??o ? uma rota bastante vi?vel para produ??o desses componentes. Entretanto, a baixa solubilidade entre cobre e molibd?nio dificulta a obten??o de densidade igual ou pr?xima da densidade te?rica. Este trabalho investiga a obten??o do comp?sito Mo-27,82%?Cu preparado por moagem de alta energia e mistura mec?nica dos p?s de cobre e heptamolibdato de am?nio (HMA) de f?rmula qu?mica (NH4)6Mo7O24 .4H2O, decomposto e reduzido por H2, antes e durante a sinteriza??o, evidenciando duas rotas de fabrica??o diferentes para o material. A influ?ncia da press?o de compacta??o na densifica??o e microestrutura do comp?sito Mo-27,82%?Cu tamb?m foi investigada. Para isto, os p?s mo?dos por 50 horas foram prensados a 200, 400 e 600 MPa. Para se entender o efeito da temperatura na densidade e microestrutura do comp?sito Mo-27,82%?Cu, amostras foram sinterizadas a 1000, 1100 e 1200 oC. Os corpos prensados a 200 e 400 MPa e sinterizados a 1200 oC alcan?aram a maior densidade entre as amostras produzidas, no valor de 94?0,4 % da densidade te?rica. Por?m, aqueles que foram decompostos e reduzidos durante a sinteriza??o apresentaram trincas de fabrica??o. J? os corpos sinterizados a 1100 oC atingiram o maior valor de microdureza (571,70?78,82 HV), apesar de uma baixa densidade em rela??o a te?rica (79,17?1,78%). / The Mo-Cu composite is a material used for electrical contact and heat sinks due its excellent properties of thermal and electrical conductivity and cooper good workability allied to its great resistance welding and electrical arc erosion of molybdenum. In the first case, simple shapes are required and the infiltration of the pre-sintered molybdenum skeleton with liquid copper is the technique of consolidation normally used. On the second case, more complex geometries and a density near or equal the theoretical density are required for the application as heat sink. The powder metallurgy is a very viable route for the production of these components, through the techniques of powder preparation processed by mechanical alloying, compaction or casting. However, the low dissolution of one component in the other and the liquid copper high contact angle on the molybdenum phase difficult the obtainment of a density near or equal the theoretical density. This research investigates the obtainment of the Mo-27,82%?Cu composite prepared by mechanical alloying and mechanical mix of the copper powders and ammonium heptamolybdate (HMA) of chemical formula (NH4)6Mo7O24 .4H2O, decomposed and reduced by ?2 before and during the sintering, showing two different fabrication routes for the material. The compaction pressure influence at the densification and microstructure of the Mo-27,82%?Cu composite were also investigated. For this, the powder milled for 50 hours and the mixed powder were pressed at 200, 400 and 600 MPa. In order to understand the temperature effect at the density and microstructure were sintered at 1000, 1100 and 1200 ?C. The bodies pressed at 200 and 400 MPa and sintered at 1200?C reached 94?0,4 % of the theoretical density. However, those which were decomposed and reduced during sintering showed manufacturing cracks. On the other hand, the bodies sintered at 1100 ?C reached the highest microhardness value (571,70?78,82 HV), despite a low theory density (79.17 ? 1.78%).

Um resultado clássico em Geometria Diferencial, conhecido como teorema de Hadamard, e demonstrado pelo mesmo ([Ha]), estabelece que uma superfície conexa compacta no espaço Euclidiano cujas curvaturas principais são todas positivas é o bordo de um corpo convexo. Em part icular, a superfície é difeomorfa a uma esfera. Neste trabalho apresentamos extensões parciais deste teorema para imersões de codimensão arbitrária e para outros espaços ambientes que o E uclidiano conforme feito em [R]. / A classical result in differential geometry, known as Hadamard's theorem and proved by himself ([Ha]). establishes that a compact connected surface in the Euclidean space whose principal curvatures are everywhere positive is the boundary of a convex body. In particular, the surface is diffeomorphic to a sphere. In this work we present IJartial extensions of this theorem to immersions of arbitrary codimension and to other spaces than the Euclidean one, as clone in [R].

Um resultado clássico em Geometria Diferencial, conhecido como teorema de Hadamard, e demonstrado pelo mesmo ([Ha]), estabelece que uma superfície conexa compacta no espaço Euclidiano cujas curvaturas principais são todas positivas é o bordo de um corpo convexo. Em part icular, a superfície é difeomorfa a uma esfera. Neste trabalho apresentamos extensões parciais deste teorema para imersões de codimensão arbitrária e para outros espaços ambientes que o E uclidiano conforme feito em [R]. / A classical result in differential geometry, known as Hadamard's theorem and proved by himself ([Ha]). establishes that a compact connected surface in the Euclidean space whose principal curvatures are everywhere positive is the boundary of a convex body. In particular, the surface is diffeomorphic to a sphere. In this work we present IJartial extensions of this theorem to immersions of arbitrary codimension and to other spaces than the Euclidean one, as clone in [R].

Nanotecnologia é o conjunto de conhecimentos acumulados pelo homem que permite controlar a produção de estruturas com uma ou mais dimensões nanométricas. Desde seus primórdios na década de 70, a nanotecnologia tem estado em constante ascensão, encontrando uma diversidade enorme de aplicações, como por exemplo em medicina e na indústria optoeletrônica. Por consequência, a demanda por equipamentos tanto de preparo como de caracterização/controle tem crescido exponencialmente. O uso da radiação X no estudo de dispositivos nanoestruturados tem sido, em grande parte, possível gra- ças as fontes síncrotrons com feixes intensos. Mas a disponibilidade desses laboratórios de alta tecnologia está aquém da crescente demanda das pesquisas em nanotecnologia, as quais precisam de técnicas de análise estrutural rápidas e de fácil acesso para otimização e controle da produção de dispositivos nanoestruturados. Com foco nessa falta por técnicas de análise estrutural, esta dissertação tem como objetivo avaliar quais parâmetros básicos de nanodispositivos, com substratos monocristalinos, podem ser investigados por meio de técnicas de difração de raios X utilizando fontes compactas de radiação, bem como avaliar as limitações instrumentais. / X-ray radiation has provided a powerful tool for analyzing the structure of materials at atomic scale. While many are fascinated with the perspectives oered by advanced X-ray sources, the practical aspects of these perspectives in the actual and future scenery of nanotechnology needs to be discussed. Nanotechnology, i.e. the capacity of controlling matter at atomic-molecular scales and manufacturing structures with dimensions of a few tens of nanometers, has provided a constant challenge for structural analysis via X-ray techniques. The great diversity of materials and methods derived from nanotechnology is generating a huge demand for time of analysis, much beyond of that can be supplied by synchrotron facilities worldwide. In optimizing nanostructured materials and devices processing methods, fast and easy-access techniques to control and characterization are required. Microscopy and spectroscopy techniques are very important in this scenery, but they have intrinsic limitations that have justied the search for high-resolution techniques of structural analysis, such as those obtained by diraction of X-rays. The use of Xradiation in the study of nanostructured device has been possible by synchrotron sources due to the high intense beams. But the availability of these high tech laboratories falls short of the growing demand for nanotechnology research. In this context, this dissertation intend evaluate which basic parameters of nanodevices with single crystal substrates can be investigated by techniques of X-ray diraction using compact radiation sources as well how to evaluate the instrumental limitations .

The midbrain dopamine system is involved in many aspects of purposeful behaviour and, when compromised, can have devastating effects on movement and cognition as seen in diseases like Parkinson's. In the healthy brain, dopamine neurons are thought to play particularly important roles in learning by signalling errors in reward prediction. The objective of this thesis was to investigate the diversity in the functional properties of the midbrain dopamine system, and how this is altered through genetic variation of relevance to Parkinson's and development of cell phenotype. This objective was addressed with a combination of behavioural experiments, in vivo single-cell recording and labelling (both in anaesthetised as well as awake rodents), immunofluorescence labelling, retrograde tracing and stereology. In a first set of experiments, it was demonstrated that chronic as well as acute genetic challenges can alter the firing patterns of midbrain dopamine neurons. Using a novel bacterial artificial chromosome-transgenic rat model, it was shown that the R1441C mutation in human leucine-rich repeat kinase 2, which is linked to Parkinson's, leads to motor deficits and an age-dependent reduction in the in vivo firing variability and burst firing of substantia nigra pars compacta (SNc) dopamine neurons. These findings help reveal processes of early, pre-degenerative dysfunction in dopamine neurons in Parkinson's. Similar effects on firing variability and burst firing of SNc dopamine neurons were found in a mouse model with conditional knock- out of the transcription factors Forkhead box A1 and A2 (FoxA1/2) in midbrain dopamine neurons. These findings indicate that FoxA1/2 are not only crucial for the early development of dopamine neurons, but also their function in the mature brain. In a second set of experiments in wildtype mice, it was demonstrated that midbrain dopamine neurons (located in SNc and ventral tegmental area) show diverse expression of the molecular markers Calbindin, Calretinin, Aldh1a1, Sox6, Girk2, SatB1 and Otx2. It was found that selective expression of these markers is of use for discriminating between midbrain dopamine neurons that project to dorsal striatum or nucleus accumbens. To elucidate whether the diverse molecular marker expression would map onto dopamine neurons whose firing correlates with distinct behavioural events, midbrain dopamine neurons were recorded and labelled in head-fixed awake mice either exposed to neutral sensory stimuli or performing a classical conditioning paradigm. The population activity of midbrain dopamine neurons was not modulated by neutral sensory stimuli. Interestingly, fewer than 50% of identified dopamine neurons showed phasic firing increases following reward- predicting cue and/or reward delivery, despite the common assumption that most (if not all) midbrain dopamine neurons signal reward prediction errors. Instead, firing was modulated by other explanatory factors, such as licking, or showed no modulation during the task. Response types of midbrain dopamine neurons were not correlated with their anatomical location nor the selective or combinatorial expression of the markers Aldh1a1, Calbindin and Sox6. In conclusion, the first set of experiments identified how different genetic burdens can alter the in vivo firing of midbrain dopamine neurons, and provide new insights into how circuits can change in pathological or compensatory ways at early disease stages in Parkinson's. The second set of experiments revealed striking heterogeneity of midbrain dopamine neurons in the intact system, and established further a functional diversity in the response types of identified midbrain dopamine neurons that is only partially consistent with canonical reward prediction error signalling.

In this work we demonstrate a theorem obtained by F. Hang and X. Wang, which ensures that a compact Riemannian manifold (Mn,g) with nonempty boundary, Ricci curvature greater or equal to (n-1)g, boundary isometric to the (n-1)-dimensional sphere and second fundamental form nonnegative, is isometric to the hemisphere . That result was published in this year in Journal of Geometric Analysis with the title Rigidity Theorems for Compact Manifolds with Boundary and Positive Ricci Curvature. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação apresentamos a demonstração de um teorema obtido por F. Hang e X. Wang, o qual estabelece que uma variedade (Mn,g) Riemanniana compacta com bordo não-vazio, curvatura de Ricci maior ou igual a (n-1)g, e com bordo isométrico à esfera (n-1)-dimensional e segunda forma fundamental não-negativa, é isométrica ao hemisfério . Este artigo foi publicado em 2009 no Journal of Geometric Analysis, com o título Rigidity Theorems for Compact Manifolds with Boundary and Positive Ricci Curvature.