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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Capilaroscopia na DMTC: um processo dinâmico associado ao envolvimento intersticial pulmonar e à gravidade de doença / Capillaroscopy in MCTD: a dynamic process associated to lung interstitial involvement and disease severity

Adriana de Holanda Mafaldo Diogenes 03 October 2006 (has links)
Selecionamos consecutivamente 63 pacientes com doença mista do tecido conectivo (DMTC) (Kasukawa, 87) para determinar a relevância do padrão SD. Ter uma capilaroscopia periungueal (CPU) até cinco anos antes do início do estudo foi o principal critério de inclusão. Na entrada, avaliamos o envolvimento de órgãos e os auto-anticorpos. A idade média e o tempo de doença foram 45,3 + 10 e 8,45 + 5,42 anos, respectivamente. O padrão SD foi observado em 41 pacientes na entrada (65%) e em 45 na CPU prévia (71,5%), p = 0,20. Dez pacientes (16%) alteraram a CPU, 7 normalizaram e 3 desenvolveram padrão SD. O tempo de doença, número e freqüência de órgãos envolvidos foram semelhantes em pacientes com e sem padrão SD. Em contraste, a análise de cada parâmetro do padrão SD mostrou uma freqüência significativamente menor de áreas avasculares (AA) moderadas/graves na entrada, comparada com a CPU anterior (26,5 e 53%, p = 0,013). Além disto, 76% dos pacientes com doença intersticial pulmonar (TCAR) tiveram AA na entrada, enquanto apenas 24% dos pacientes com esta alteração não apresentavam este achado à CPU (p = 0,017). Adicionalmente, reduzida densidade capilar foi freqüentemente observada em pacientes submetidos à terapia imunossupressora, quando comparados com o grupo sem este tratamento (66,7 e 33,3%, p = 0,001). A CPU na DMTC é um processo dinâmico e a análise de cada parâmetro do padrão SD parece ser um bom indicador de doença intersticial pulmonar e gravidade de doença. / For determining the clinical relevance of SD-pattern in MCTD, sixty-three MCTD patients (Kasukawa´s criteria) were consecutively selected. The main inclusion criterion was availability of previous nailfold capillaroscopy (NC) 5 years before inclusion. At entry, organ involvement and autoantibody evaluation were performed. The mean age and disease duration were 45.3 + 10 and 8.45 + 5.42 years, respectively. SD-pattern was observed in 41 patients at entry (65%) and in 45 at previous NC (71.5%), p = 0.20. Ten patients (16%) changed NC, 7 normalized, and 3 developed SD-pattern. Disease duration, number and frequency of organ involvement were similar in patients with and without SD-pattern. In contrast, analysis of each SD-pattern parameter revealed a significant lower frequency of moderate/severe avascular areas (AA) at entry compared to previous examination (26.5 vs. 53%, p = 0.013). Moreover, 76% of patients with interstitial lung disease (HRCT) had AA at entry, whereas only 24% of patients with this alteration did not have this NC finding (p = 0.017). Furthermore, reduced capillary density was frequently observed in patients taking immunosuppressive therapy than those without (66.7 vs. 33.3%, p = 0.001). NC in MCTD is a dynamic process and analysis of each SD-pattern parameter seems to be a good indicator of lung involvement and disease severity
302

"Pneumonias intersticiais idiopáticas: da patogênese e do remodelamento aos determinantes anátomo-clínico-radiológicos de prognóstico e sobrevida com ênfase ao componente vascular" / Idiopathic interstitial pneumonias : of the pathogenesis and remodeling to anatomic-physician-radiological determinatives of prognostic and survival with emphasis to the vascular component

Edwin Roger Parra Cuentas 04 May 2006 (has links)
Estudou-se por morfologia, morfometria e imuno-histoquímica o remodelamento vascular (moléculas de adesão), epitelial (moléculas de adesão) e intersticial (colágeno V e células imunes) nos três tipos maiores de pneumonias intersticiais idiopáticas: em 62 casos de IPF, 22 casos de NSIP e 25 casos de AIP. O impacto dessas alterações foi avaliado nas provas de função, sobrevida e prognóstico. Demonstrou-se que o remodelamento vascular ativo e fibroelastótico é diretamente proporcional ao grau de atividade parenquimatosa principalmente na UIP. O colágeno V, o mapeamento das células imunes, o aumento da atividade endotelial e epitelial tiveram impacto no espectro diferencial e possivelmente na patogênese das três pneumonias intersticiais estudadas. A resposta imune celular na UIP teve impacto na sobrevida dos pacientes / Studied for morphology, morphometry and immunohischemistry the vascular (adhesion molecules), epithelial (adhesion molecules) and interstitial (collagen V and immune cells) remodeling in the three major types of idiopathic interstitial pneumonias: in 62 cases of IPF, 22 cases of NSIP, and 25 cases of AIP. The impact of these alterations was evaluated in the function tests, survival and prognostic. We demonstrated that the active and fibroelastotic vascular remodeling is directly proportional to the degree of parenchymal activity, mainly in the UIP. Collagen V, mapping of the immune cells, increase of the endothelial and epithelial activity had possibly impact in the distinguishing specter and in pathogenesis of the three interstitial pneumonias studied. The cellular immune reply in the UIP it had impact in survival of the patients
303

Avaliação pulmonar funcional, tomográfica e de escores de gravidade de crianças e adolescentes com lúpus eritematoso sistêmico juvenil (LESJ) / Assessment of pulmonary function, tomographic findings, and severity scores in children and adolescents with childhood-onset systemic lupus erythematosus (cSLE)

Claudine Sarmento da Veiga 19 May 2015 (has links)
Introdução: Alterações pulmonares podem ocorrer no lúpus eritematoso sistêmico juvenil (LESJ) e estar relacionadas com a morbidade e mortalidade. Os objetivos deste estudo foram analisar a função pulmonar de pacientes com LESJ e identificar possíveis correlações com escore da tomografia de alta resolução (TCAR) do tórax, escore de atividade da doença, dano cumulativo da doença e qualidade de vida dos pacientes. Métodos: Quarenta pacientes com LESJ, de 7,4 a 17,9 anos (mediana: 14,1 anos), foram submetidos a espirometria e pletismografia. Difusão de monóxido de carbono (DLCO), TCAR do tórax, teste da caminhada de 6 minutos (TC6M), atividade da doença, dano cumulativo da doença e qualidade de vida também foram avaliados. Resultados: Alterações subclínicas foram observadas em 19/40 (47,5%) pacientes com LESJ na espirometria/DLCO. O volume expiratório forçado no primeiro segundo (VEF1%) foi o parâmetro mais afetado (30%). A TCAR de tórax estava alterada em 22/30 (73,3%) pacientes, sendo alterações mínimas em 43%. Sinais de envolvimento de vias aéreas foram observados em 50% dos casos. Doze pacientes (30%) foram hospitalizados por complicações pulmonares decorrentes do LESJ, com alta hospitalar há pelo menos 11 meses antes do início do estudo (mediana da alta: 2,1 anos). Capacidade pulmonar total (CPT%), capacidade vital (CV%), capacidade vital forçada (CVF%) e VEF1% foram menores no grupo que foi hospitalizado quando comparado com o grupo sem hospitalização por complicações pulmonares (p < 0,05). Houve correlação entre o escore da TCAR com VEF1/VC (r=-0.63; p=0.0002), VEF1 (r=-0.54; p=0.018), FEF25-75% (r=-0.67; p < 0.0001) e resistência das vias aéreas (r=+0.49; p=0.0056). A DLCO apresentou correlação com o tempo de doença (r=+0.4; p=0.01). Conclusão: Aproximadamente metade dos pacientes com LESJ apresentaram alterações funcionais significativas independentemente da atividade da doença e do dano cumulativo. Alterações de vias aéreas foram predominantes, especialmente na TCAR. A correlação positiva entre a DLCO e duração da doença provavelmente está relacionada com a melhora decorrente do tratamento. Complicações pulmonares decorrentes do LESJ podem determinar dano funcional / Introduction: Pulmonary abnormalities can occur in childhood-onset systemic lupus erythematosus (cSLE) and can affect both morbidity and mortality. The aims of this study were to analyze the pulmonary function of cSLE patients and to identify possible correlations with the high-resolution computed chest tomography (HRCT) score, disease activity, disease cumulative damage and the participants\' quality of life. Methods: Forty cSLE patients, median age: 14.1 years (range: 7.4-17.9), underwent spirometry and plethysmography. Carbon monoxide diffusing capacity (DLCO), HRCT, 6-minute walk test (6MWT), disease activity, disease cumulative damage and quality of life were assessed. Results: Subclinical abnormalities were evident in 19/40 (47,5%) cSLE patients according to spirometry/DLCO. Forced expired volume in one second (FEV1%) was the parameter most affected (30%). The HRCT showed some abnormality in 22/30 patients (73,3%), which were minimal in 43%. Signs of airway affection were found in 50%. Twelve patients (30%) were hospitalized due to cSLE-related pulmonary complications, at least 11 month before the study began (median discharge: 2.1years earlier). Total lung capacity (TLC%), vital capacity (VC%), forced vital capacity (FVC%), and FEV1% were lower in the group with hospitalization (p < 0.05). The HRCT-score was correlated with FEV1/VC (r=-0.63; p=0.0002), FEV1 (r=-0.54; p=0.018), FEF25-75% (r=-0.67; p < 0.0001), and resistance (r =+ 0.49; p=0.0056). DLCO was correlated with disease duration (r =+ 0.4; p=0.015). Conclusions: Almost half of patients with cSLE exhibited significant functional abnormalities, regardless of the disease activity and disease cumulative damage. Airway abnormalities were predominant, especially in the HRCT. The positive correlation between DLCO and duration of disease is most likely related to improvement resulting from treatment. The cSLE-related pulmonary complications can determine functional damage
304

[en] OPTICAL FIBER SENSOR DISCRIMINATOR FOR JACKETED TANKS LEAKAGE DETECTION / [pt] SENSOR DISCRIMINATIVO A FIBRA ÓPTICA PARA DETECÇÃO DE VAZAMENTO EM TANQUES JAQUETADOS

BRUNO PEREIRA ROSAS 09 December 2003 (has links)
[pt] A contaminação do solo nos postos de serviço é um risco ambiental associado à atividade de distribuição de derivados de petróleo que precisa ser controlado. O aumento deste risco está diretamente ligado à idade dos tanques e tubulações e à baixa qualidade na operação dos postos. Tais problemas vêm sendo minimizados ao longo das duas ultimas décadas graças à utilização de equipamentos mais modernos e das crescentes exigências ambientais. Nesta tese foi desenvolvido e testado em laboratório um equipamento de controle ambiental, baseado em tecnologia de sensores a fibra óptica, para a detecção de vazamentos em tanques jaquetados (dupla parede). A detecção de vazamentos neste tipo de tanque tornou-se uma exigência dos órgãos de proteção ambiental. O uso de tanques jaquetados com sistema de detecção permite que seja evitado o contato dos fluidos combustíveis com o solo, pois, uma vez rompida a parede interna de aço carbono do tanque, o sistema acusa a presença de hidrocarbonetos no interstício do tanque. Outrossim, a discriminação do fluido quando ocorrido o vazamento é importante para que se possa detectar mais facilmente se o rompimento se deu na parede interna ou externa do tanque, possibilitando um rápido diagnóstico e a conseqüente tomada de medidas corretivas do problema. Com a evolução legislativa no campo ambiental e o foco do Poder Público na garantia de uma maior qualidade de vida, o País está passando por um momento de transição onde, em um curto espaço de tempo, quase que 70 por cento dos tanques em operação deverão ser substituídos. Dessa feita, o equipamento para monitoramento ambiental desenvolvido nesta tese visa também tornar economicamente possível a substituição do atual parque de tanques por novos, já com sensores ópticos incorporados. / [en] Soil contamination due to leakage of hydrocarbon fuels from tanks in service stations is an environmental risk associated with the distribution segment of the petroleum industry. Such risk is closely related to ageing tanks and piping systems, as well as to the lack of quality assurance practices in service stations. This problem is being reduced during the last two decades, mainly due to use of modern equipment that must adhere to more rigid environmental legislation. In this thesis, an optical fiber sensor, able to discriminate different liquids, has been developed as a part of a leakage detection system employed to monitor jacketed tanks used to store alcohol or hydrocarbon or fuels. Leakage detection in this type of storage tanks plays an important role to minimize problems due to soil contamination and is now required according to new environmental legislation. If fuel leaks through the carbon steel wall of jacketed tanks it will be contained, within an interstitial space, by the outer, fiber reinforced, polymeric wall of the tank. Presence of fluid in the interstitial space is monitored by the optical fiber sensor, which sends a warning to the service station operator, which immediately has to start maintenance procedures. The capability of discriminating different fuels will allow the operator to quickly identify from which tank compartment the leakage has originated, or, if water coming from the soil has been detected, that the outer wall of the tank has been damaged and needs to be repaired.
305

Avaliação tomográfica do acometimento das pequenas vias aéreas nas doenças intersticiais do pulmão / Tomographic evaluation of the small airways in the interstitial lung diseases

Rocha, Marcelo Jorge Jacó 14 August 2007 (has links)
A patogênese da fibrose pulmonar idiopática (FPI), forma mais comum de pneumonia intersticial idiopática, não é bem conhecida. Os estudos histopatológicos evidenciam uma extensa lesão do epitélio alveolar com destruição intensa dos pneumócitos tipo e exposição e perda de integridade da membrana basal subjacente, impedindo a reepitelização e rendotelização alveolar, com conseqüente proliferação de fibroblastos e deposição de matriz extracelular. O fator etiológico responsável por essa resposta fibrosante ainda não é conhecido. Em doenças como a síndrome do desconforto respiratório agudo (SDRA) e a lesão pulmonar induzida pela ventilação mecânica, o papel da abertura e fechamento cíclicos das pequenas vias aéreas já está bem estabelecido. Esse estudo tem como objetivo avaliar a presença de colapso alveolar e de pequenas vias aéreas em pacientes com FPI através de tomografia computadorizada (TC) de tórax multislice. As tomografias foram realizadas em 3 diferentes momentos do ciclo respiratório - na capacidade pulmonar total (CPT), na capacidade residual funcional (CRF) e no volume residual (VR) - inicialmente em ar ambiente (O2 a 21%) e as duas últimas etapas, CRF e VR, foram repetidas após 10 minutos de ventilação com O2 a 100%. Admitimos que o surgimento de colapso alveolar após a manobra com O2 a 100% se deve ao fechamento das pequenas vias aéreas seguido de atelectasia de absorção. Foi utilizado o programa Osiris para análise quantitativa das densidades pulmonares e um programa em linguagem LabVIEW 6.0 para quantificação da massa de pulmão não aerado (colapsado) cuja densidade situa-se entre -100 e + 100 UH. A casuística foi composta por 18 pacientes com diagnóstico histológico e/ou clínico de FPI e 12 controles sem doença respiratória conhecida. Os indivíduos do grupo controle foram mais idosos (63 x 70 anos), não havendo diferença quanto à história de tabagismo. A atenuação média do parênquima pulmonar foi maior no grupo fibrose na CPT, CRF 21% e VR 21%. Quando analisamos a massa de pulmão não aerado, o grupo fibrose apresentou valores significativamente maiores do que o grupo controle em todos os volumes respiratórios avaliados em ar ambiente e após O2 a 100%. A avaliação da massa de pulmão não aerado no VR e na CRF após ventilação com O2 a 100%, em comparação com os mesmos volumes pulmonares em ar ambiente, mostrou aumento do colapso tanto em pacientes quanto em controles, não havendo diferença entre os grupos quando se comparou o aumento absoluto da massa de pulmão não aerado após essa manobra. Entretanto, no grupo de pacientes com FPI, houve aumento significativo da massa de pulmão não aerado à medida que se reduziram os volumes pulmonares em ar ambiente, alteração essa não encontrada no grupo controle. Podemos concluir que a ventilação com O2 a 100% causou colapso de vias aéreas tanto nos pacientes quanto no grupo controle. Nos pacientes com FPI, foi evidenciado colapso alveolar durante a ventilação em ar ambiente, colapso esse quase totalmente revertido (88%) após uma manobra de inspiração máxima até a CPT, o que demonstra seu potencial de reversibilidade / The pathogenesis of idiophatic pulmonary fibrosis (IPF), the most common form of idiopathic interstitial pneumonias, is not completely understood. It is related to a type I pneumocyte injury with loss of basement membrane integrity and failure of normal re-epithelialization and re-endothelialization leading to fibroblast proliferation and extra cellular matrix deposition. However, the etiology of this fibroproliferative response is unknown. In ARDS and ventilator-induced lung injury, it has been postulated that the pulmonary injury is caused by the cyclic opening and closing of collapsed airways. Our aim is to measure the collapsed areas of the lung (alveolar and small airways collapse) using a multislice computed tomography (CT) in a group of patients with IPF. They were submitted to a CT scan of the thorax in 5 different situations: at total lung capacity (TLC), functional residual capacity (FRC) and residual volume (RV) at 21% O2 as well as at FRC and RV after breathing 100% O2 for 10 minutes. We assumed that the gain in collapsed areas after 100% O2 corresponds to trapped areas with airways closure and absorption atelectasis. We employed the Osiris Software program to the quantitative analysis of CT attenuation of lung tissue and a program written in LabVIEW to measure the mass of nonaerated lung tissue (- 100 to +100 HU). Eighteen IPF patients and twelve controls without respiratory disease were studied. The control group was older than IPF group (70 x 63 years, respectively) and the smoking history was not different between both groups. The mean lung attenuation was higher in IPF patients at TLC, 21% FRC and 21% RV. When we analyzed the mass of nonaerated lung tissue, the IPF group showed significantly higher values in all respiratory maneuvers (TLC, FRC and RV) at 21% O2 and 100% O2. Both groups presented an increase in collapsed areas when exposed to 100% at RV and FRC and this increment was of similar magnitude. However, only IPF patients had an increase in the mass of nonaerated lung tissue when the lung volume was reduced from TLC to FRC and from FRC to RV during air breathing. We concluded that patients and controls had airways collapse after 100% O2 breathing. In contrast, only IPF patients demonstrated alveolar collapse during air breathing which was almost completed reversible after TLC maneuver
306

Análise de polimorfismos de nucleotídeo único na cistite intersticial / Single nucleotide polymorphism analysis in interstitial cystitis

Cassão, Valter Dell Acqua 08 December 2017 (has links)
IINTRODUÇÃO: A Cistite Intersticial (CI) ou Síndrome da Bexiga Dolorosa (SBD) é uma síndrome crônica caracterizada pela presença de dor ou desconforto vesical ou pélvico e sintomas miccionais como urgência e aumento da frequência miccional diurna e noturna, na ausência de outra afecção identificável que justifique esses sintomas. Não existe até o momento nenhum teste diagnóstico ou marcador que defina a CI. Desta forma seu diagnóstico é predominantemente clínico, baseado nos sinais e sintomas e dependente da exclusão de outras doenças urológicas. A dificuldade no diagnóstico e no tratamento dessas pacientes reflete o pouco que se sabe sobre sua fisiopatologia e sobre as alterações genéticas presentes na doença. A identificação de marcadores pode proporcionar um melhor entendimento e manejo desses aspectos da síndrome. Na tentativa de identificar marcadores genéticos que possam estar associados a CI, avaliamos a presença de alguns polimorfismos genéticos, os polimorfismos de nucleotídeo único (SNP), no DNA de pacientes com os critérios diagnósticos de CI e comparamos sua prevalência entre as pacientes e também com um grupo controle representativo da população geral. A correlação desses polimorfismos considerando a CI e a intensidade de dor nessas pacientes ainda não foi estudada na literatura. OBJETIVOS: Analisar a presença de polimorfismos (SNP) em amostras de sangue de pacientes com CI e correlacionar a presença dos polimorfismos com o quadro de dor crônica. MÉTODOS: Foram selecionadas 34 pacientes do sexo feminino com diagnóstico de CI de acordo com os critérios do NIDDK e 23 pacientes do grupo controle (mulheres saudáveis apenas com incontinência urinária de esforço). As pacientes com o diagnóstico de CI foram estratificadas em dois grupos de acordo com o grau dos sintomas de dor crônica. Foram selecionados 20 polimorfismos para análise: rs1800871, rs1800872, rs1800896, rs1800471, rs1800629, rs361525, rs1800497, rs6311, rs6277, rs6276, rs6313, rs2835859, rs11127292, rs2243248, rs6887695, rs3212227, rs1799971, rs12579350, rs3813034, rs6746030. A genotipagem foi realizada através da técnica de PCR em tempo real (q-PCR) e correlacionada com o diagnóstico de CI e com a intensidade dos sintomas álgicos. RESULTADOS: O alelo polimórfico (T) do SNP rs11127292 foi mais frequente nas pacientes com CI em relação ao grupo controle (p:0,01). O alelo polimórfico (T) do SNP rs6311 foi significativamente mais frequente nas pacientes com dor mais intensa (p:0,03). A frequência do alelo selvagem (A) do SNP rs1799971 foi maior em pacientes com dor leve a moderada (p:0,04). CONCLUSÕES: Foram identificadas algumas diferenças na frequência dos polimorfismos nas pacientes estudadas, o que sugere a existência de um papel relevante dos SNP associados tanto à CI quando na intensidade dos sintomas de dor crônica nestas pacientes / INTRODUCTION: Interstitial cystitis (IC) or painful bladder syndrome (PBS) is a chronic syndrome characterized by the presence of bladder/pelvic pain or discomfort and voiding symptoms such as urgency and increased urinary waking and night-time frequency in the absence of another identifiable cause to justify these symptoms. So far, there is no diagnostic test or marker to establish the presence of IC. Thus, the diagnosis is predominantly clinical, based on signs and symptoms and dependent on the exclusion of other urological diseases. The difficulty in the diagnosis and treatment of these patients reflects the little that is known about IC physiopathology and about the genetic background of the disease. The identification of new markers may provide a better understanding and management of the syndrome. As an attempt to identify genetic markers that may be associated with IC, we evaluated the presence of some genetic polymorphisms, single nucleotide polymorphisms (SNPs), in the DNA of patients with the diagnostic criteria of IC, and we compared their prevalence among IC patients and with a control group representative of the general population. The correlation of these polymorphisms considering IC and pain intensity in these patients has not been studied in the literature. OBJECTIVES: To assess the presence of polymorphisms (SNPs) in blood samples from IC patients and to correlate the presence of polymorphisms with chronic pain. METHODS: Thirty-four female patients with a diagnosis of IC according to the NIDDK criteria and 23 control subjects (healthy women with stress urinary incontinence) were selected. Patients with the diagnosis of IC were stratified into two groups according to the degree of symptoms of chronic pain. We selected 20 polymorphisms for analysis: rs1800871, rs1800876, rs1800471, rs1800629, rs361525, rs1800497, rs6311, rs6277, rs6276, rs6313, rs2835859, rs11127292, rs2243248, rs6887695, rs3212227, rs1799971, rs12579350, rs3813034, rs6746030. Genotyping was performed using the real-time PCR technique (q-PCR) and correlated with the diagnosis of IC and intensity of pain symptoms. RESULTS: The polymorphic allele (T) of the SNP rs11127292 occurred with more frequency in patients with IC compared to the control group (p= 0.01). The polymorphic allele (T) of SNP rs6311 occurred with more frequency in patients with severe pain (p= 0.03). The frequency of wild-type (A) SNP rs1799971 was higher in patients with mild to moderate pain (p= 0.04). CONCLUSION: The results indicated differences in polymorphism frequency in the patients studied, suggesting the existence of a relevant role of SNPs associated with both IC and intensity of chronic pain symptoms in these patients
307

Tuning of single semiconductor quantum dots and their host structures via strain and in situ laser processing

Kumar, Santosh 27 August 2013 (has links) (PDF)
Single self-assembled semiconductor quantum dots (QDs) are able to emit single-photons and entangled-photons pairs. They are therefore considered as potential candidate building blocks for quantum information processing (QIP) and communication. To exploit them fully, the ability to precisely control their optical properties is needed due to several reasons. For example, the stochastic nature of their growth ends up with only little probability of finding any two or more QDs emitting indistinguishable photons. These are required for two-photon quantum interference (partial Bell-state measurement), which lies at the heart of linear optics QIP. Also, most of the as-grown QDs do not fulfil the symmetries required for generation of entangled-photon pairs. Additionally, tuning is required to establish completely new systems, for example, 87Rb atomic-vapors based hybrid semiconductoratomic (HSA) interface or QDs with significant heavy-hole (HH)-light-hole (LH) mixings. The former paves a way towards quantum memories and the latter makes the optical control of hole spins much easier required for spin- based QIP. This work focuses on the optical properties of a new type of QDs optimized for HSA experiments and their broadband tuning using strain. It was created by integrating the membranes, containing QDs, onto relaxor-ferroelectric actuators and was quantified with a spatial resolution of ~1 µm by combining measurements of the µ-photoluminescence of the regions surrounding the QDs and dedicated modeling. The emission of a neutral exciton confined in a QD usually consists of two fine-structure-split lines which are linearly polarized along orthogonal directions. In our QDs we tune the emission energies as large as ~23meV and the fine-structure-splitting by more than 90 µeV. For the first time, we demonstrate that strain is able to tune the angle between the polarization direction of these two lines up to 40° due to increased strain-induced HH-LH mixings up to ~55%. Compared to other quantum emitters, QDs can be easily integrated into optoelectronic devices, which enable, for example, the generation of non-classical light under electrical injection. A novel method to create sub-micrometer sized current-channels to efficiently feed charge carriers into single QDs is presented in this thesis. It is based on focused-laserbeam assisted thermal diffusion of manganese interstitial ions from the top GaMnAs layer into the underlying layer of resonant tunneling diode structures. The combination of the two methods investigated in this thesis may lead to new QDbased devices, where direct laser writing is employed to preselect QDs by creating localized current-channels and strain is used to fine tune their optical properties to match the demanding requirements imposed by QIP concepts.
308

Effect of Pre-Bending and Hydroforming Parameters on the Formability of Advanced High Strength Steel Tube

Bardelcik, Alexander January 2006 (has links)
With increasing fuel costs and the current drive to reduce greenhouse gas emissions and fuel consumption, a need to reduce vehicle weight is apparent. Weight reduction can be achieved by replacing conventionally stamped structural members with hydroformed parts. The weight reduction can be further enhanced by reducing the thickness of the hydroformed members through the use of advanced high strength steel (AHSS). A primary limitation in hydroforming AHSS, is the limited ductility or formability of these materials. This limitation becomes acute in multi-stage forming operations in which strain path changes become large making it difficult to predict formability. Thus, the focus of the current work is to study the effects of pre-bending on the subsequent hydroformability of Dual-Phase DP600 steel tubes. As part of this effort, the effect of key bending and hydroforming process parameters, bending boost and hydroforming end-feed, have been studied in a parametric fashion. <br /><br /> Multi-step pre-bending and hydroforming experiments were performed on 76. 2 mm (3. 0") OD tubes with a wall-thickness of 1. 85mm (DP600). Experiments were also performed on 1. 74mm Interstitial Free (IF) steel tube, which provided a low strength, high formability baseline material for comparison purposes. A fully instrumented servo-hydraulic mandrel-rotary draw tube bender was used in the pre-bending experiments in which various levels of boost were applied. The results showed that increased boost reduced the major (tensile) strain and thinning at the outside of the bend. At the inside of the bend, the compressive minor strain became larger and thickening increased. <br /><br /> Hydroforming of the straight and pre-bent tubes was conducted using various levels of load-control end-feed (EF). For both straight and pre-bend tube hydroforming, an increase in hydroforming EF resulted in increased burst pressure and corner-fill expansion (CFE). The effect of bending boost on CFE was also measured. For a given hydroforming EF case, a tube bent with greater boost achieved a higher burst pressure and consequently a greater CFE which increased the hydroformability of the material. Pre-bending was shown to consume a considerable amount of the formability of the tube in the hydroforming experiments. For the same EF case, the pre-bent tubes could only achieve a fraction of the straight tube CFE at burst. <br /><br /> The pre-bending and hydroforming experiments were complimented by finite element simulation in the hope of providing additional insight into these processes. The finite element (FE) models were able to accurately predict the strain and thickness changes imposed during pre-bending. The models were able to accurately predict the CFE, EF displacement, and strain and thickness distributions after hydroforming. <br /><br /> The extended stress-based forming limit curve (XSFLC) failure criterion was applied to predict failure (onset of necking) during hydroforming, which was measured as the burst pressure in the experiments. For straight tube hydroforming, the XSFLC predicted the correct failure pressure versus hydroforming EF load trend, but over predicted the failure pressures. In pre-bend hydroforming, the models were able to capture the effect of bending boost and hydroforming EF on the hydroformability of the tubes. The XSFLC was able to capture the drop in formability for bending versus straight tube hydroforming, but was unable to capture the failure pressure versus hydroforming EF load trend or magnitude. Further work is required to make the XSFLC applicable to straight and pre-bend hydroforming.
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Ökologie der Fischbestände in Fließgewässern des Khentii-Gebirges (Mongolei): Bestandsaufbau, Dynamik und Gefährdung durch den Gold-Tagebau / Ecology of fish populations in running waters of the Khentii Mountains (Mongolia): Population structure and dynamics and threats by open placer gold mining

Krätz, Daniel A. 12 June 2009 (has links) (PDF)
Die Fischfauna der Mongolei umfasst 64 Arten, von denen aktuell in der Roten Liste elf Arten als regional bedroht und vier Arten als potentiell bedroht eingestuft werden. Eine der wichtigsten Ursachen für den Rückgang der Arten ist der Gold-Tagebau. Viele Goldvorkommen lagern in alluvialen Sedimenten der Fließgewässerauen und werden durch großflächigen Abbau und mechanische Auswaschungsprozesse gewonnen. Dies führt zu erheblichen Störungen im Schwebstoff- und Stoffhaushalt der Fließgewässer und beeinflusst die Habitatverfügbarkeit und -qualität für die Fischfauna. Das primäre Ziel der Arbeit war daher die abiotische und ichthyologische Charakterisierung ausgewählter Referenzgewässer sowie durch Gold-Tagebau beeinflusster Gewässer und die Quantifizierung der Einflüsse des Gold-Tagebaus. Ein weiteres Ziel lag in der Formulierung von angepassten Managementstrategien für eine nachhaltige Entwicklung des expandierenden Bergbausektors in der Mongolei. Die Untersuchungen fanden in den Jahren 2003 bis 2006 an vier rhitralen Gewässern des Khentii-Gebirges im Nord-Osten der Mongolei statt. Die Erfassung der Fischbestände erfolgte mit Hilfe von Elektrofischfanganlagen und Reusen, wobei die vorkommenden Habitate repräsentativ erfasst wurden. Zusätzlich erfolgten Untersuchungen zum Stoffhaushalt der Gewässer und der Gewässersohle. Die relevanten Habitate wurden kartiert und Experimente zum Wanderverhalten ausgewählter Arten durchgeführt. Die Untersuchungen erbrachten folgende wesentliche Ergebnisse: 1. Die Fischfauna der untersuchten Gewässer umfasste 14 Taxa mit überwiegend rhitralen Charakterarten wie Salmoniden, Äschen und Elritzen. Die Fischbestände wiesen eine sehr hohe saisonale Dynamik auf, wobei kleinere Fließgewässer im Herbst verlassen und im Frühjahr neu besiedelt wurden. 2. Der Gold-Tagebau führte zu erhöhten Schwebstoffkonzentrationen und zur Kolmation des hyporheischen Interstitials. Die physikalisch-chemischen Untersuchungen ergaben vor allem eine signifikante Erhöhung der Wassertemperaturen in den belasteten Gewässerabschnitten. Durch den Gold-Tagebau wurden weiterhin die Auenvegetation und die natürlichen Uferstrukturen zerstört, was zu vielfältigen Habitatveränderungen führt. 3. Die untersuchten Effekte des Gold-Tagebaus sind als sublethal und verhaltens-verändernd einzustufen. Sie wirken sich z.B. auf das funktionale Gefüge der verschiedenen trophischen Ebenen des Fließgewässerökosystems aus. So wiesen zahlreiche Fischarten einen signifikant verringerten Konditionsfaktor auf, der offensichtlich bottom-up gesteuert durch verminderten Aufwuchs und geringere Abundanzen des Makrozoobenthos verursacht wird. Auch wurde ein deutlicher Einfluss auf die Fischwanderung festgestellt, der vermutlich durch ungünstige physikalisch-chemische oder hydraulische Habitateigenschaften innerhalb des Abbaugebiets verursacht wird. Für Arktische Äschen und Lenok ist das Abbaugebiet nicht oder nur eingeschränkt passierbar. 4. Die Kolmation des Kieslückensystems führte zum Verlust von Laich- und Überwinterungshabitaten und ist daher als ein gravierender Einflussfaktor für die lokale Fischfauna einzustufen. 5. Letale Effekte wie Kiemen- oder Schleimhautverletzungen auf Grund von direkter Schädigung der Tiere durch die erhöhten Schwebstofffrachten wurden nicht beobachtet. Im Rahmen der Arbeit wurden ökologische Grundlagenkenntnisse zu Fischbeständen und Populationsdynamiken im Nord-Osten der Mongolei erarbeitet. Diese Informationen tragen zu einem besseren Verständnis der Gefährdungsursachen bei. Auf Basis der gewonnenen Erkenntnisse über die Ökologie der Arten und der Einflüsse des Gold-Tagebaus wurden Managementempfehlungen unterschiedlicher Priorität formuliert und an Hand eines Fallbeispiels exemplarisch bearbeitet. Darüber hinaus wurden Grundlagen für ein ökologisches Monitoring des Gold-Tagebaus entwickelt. / The fish fauna of Mongolia comprises 64 species of which eleven are regionally endangered and four potentially endangered according to the Red List of Mongolian Fish. Gold mining is regarded as one of the major causes for declining fish populations. Many gold deposits are found in the alluvial sediments of the floodplains and are extracted by large scale mining and mechanical elutriation. This heavily disturbs the balance of suspended sediments and matter in running waters and affects the habitat availability and quality for the fish fauna. Thus, the primary objective of this study was the abiotic and ichthyological characterization of selected reference waters and waters influenced by gold mining as well as the quantification of gold mining effects. Furthermore, an aim was the formulation of management strategies for a sustainable development of the expanding mining sector in Mongolia. The investigation took place from 2003 to 2006 at four rhitral waters of the Khentii Mountains in north-east Mongolia. Data acquisition of the fish fauna was carried out with electric fishing devices and fish traps on representative habitats. In addition, the balance of mater and characteristics of the hyporheic zone were analyzed, relevant habitats mapped and the migratory behavior of selected species experimentally studied. The following major results were obtained from this research: 1. The fish fauna of the examined waters comprised 14 taxa dominated by rhitral characteristic species like salmonids, arctic grayling and minnows. The fish population was strongly seasonally influenced, whereas small running waters being repopulated yearly in spring. 2. Gold mining brings about an increase in concentrations of suspended sediment and clogging of the hyporheic interstitial. Physical-chemical investigations primarily identified a significant rise in water temperatures in the polluted water sectors. Furthermore, gold mining degrades floodplain vegetation and natural bank structures causing varied habitat changes. 3. The examined gold mining effects are sublethal to fish or influence their behavior. They disrupt the functional arrangement of the different trophic levels of the river ecosystem. Thus, the condition of some fish species was significantly decreased, evidently regulated bottom-up by depleted periphyton and reduced abundances of macro invertebrates. Moreover, a strong influence on the river continuum was assessed. Arctic grayling and lenok did not migrate through the mining area, possibly due to unfavorable physical-chemical or hydraulic conditions within the mining site. 4. The clogging of the river bed substrate resulted in a loss of spawning and hibernation habitats and thus must be regarded as a major thread to the local fish fauna. 5. Lethal effects like injuries of gills or skin by direct lesions of suspended particles could not be observed. In this study basic ecological knowledge and population dynamics of the fish fauna in north-east Mongolia have been identified. This information is fundamental for a better understanding of the causes of endangerment. Based on the findings on the ecology of fish species and the influences of gold-mining management recommendations of different priority were developed and exemplified in a case study. Furthermore, this study worked out basic principles for an ecological monitoring of gold mining.
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Les transporteurs sélectifs de cholestérol SR-BI, SR-BII, CD36 et ABCA1 contribuent au maintien de l’homéostasie du cholestérol intratesticulaire

Akpovi, D. Casimir 09 1900 (has links)
Le testicule assure la production des spermatozoïdes et la sécrétion de la testostérone. Chaque fonction est assumée par un compartiment cellulaire distinct: l’épithélium séminifère et le tissu interstitiel. Le cholestérol, présent dans les deux compartiments, est un composé indispensable aux membranes cellulaires et un précurseur essentiel de la testostérone. Dans le compartiment interstitiel, environ 40 % du cholestérol utilisé pour la production hormonale est importé du sang à partir des lipoprotéines HDL et/ou LDL. Dans l’épithélium séminifère, la cellule de Sertoli assure le contrôle et le maintien de la spermatogenèse. Elle a la capacité de synthétiser du cholestérol à partir de l’acétate in vitro, néanmoins, il n’y a pas d’évidence qu’elle le fait in vivo. De plus il existe, au niveau des tubules séminifères, une barrière hémato-testiculaire qui empêche le libre passage de plusieurs composés sanguins, y compris le cholestérol. Nous avons testé l’hypothèse qu’il existe des moyens d’importation du cholestérol sanguin, mais aussi l’exportation du cholestérol intra-tissulaire, qui contourneraient cette barrière et qui contribueraient au maintien du taux intratubulaire du cholestérol compatible avec le bon déroulement de la spermatogenèse. Nous avons comparé les taux de variation de l’expression de l’ARNm et de la protéine des transporteurs sélectifs de cholestérol SR-BI, SR-BII, CD36 et ABCA1 aux taux de variation du cholestérol libre et estérifié au cours de la spermatogenèse chez les souris normales durant le développement postnatal. Afin de mieux apprécier le niveau d’implication de chacun de ces récepteurs, nous avons examiné comment la suppression du gène d’une enzyme comme la lypase hormono-sensible (HSL) ou de celui d’un transporteur de cholestérol comme SR-BI, CD36 ou NPC1 était compensée et comment cette suppression affectait le taux de cholestérol libre et estérifié dans chacun des deux compartiments cellulaires du testicule. Nous avons dans un premier temps mis au point une nouvelle technique d’isolation des testicules en fraction enrichie en tissu interstitiel (ITf) et en tubules séminifères (STf) qui a l’avantage de mieux préserver l’intégrité des formes phosphorylées et glycosylées des protéines comparée aux techniques préexistantes. Les résultats de nos analyses ont montré que l’expression de SR-BI et CD36 étaient maximales dans les ITf au moment où les souris ont complété leur maturité sexuelle et où le niveau de synthèse de la testostérone était maximal. Dans les tubules séminifères, l’expression maximale de SR-BI et le taux le plus élevé de cholestérol estérifié étaient mesurés de façon concomitante à 35 jours après la naissance, au moment où la première vague de l’activité spermatogénétique était complétée. L’expression de l’ABCA1 était maximale au moment où le taux de cholestérol était élevé et minimale au moment où le taux de cholestérol était le plus bas, alors que le niveau d’expression de CD36 était maximal chez l’adulte au moment où le taux de spermiation était le plus élevé. L’expression de SR-BII variait peu dans les deux compartiments cellulaires durant le développement. La suppression génétique de la HSL et de NPC1, qui cause une infertilité chez les souris mâles, était accompagnée d’une accumulation de cholestérol libre et estérifié dans les tubules séminifères. Par contre, la suppression génétique de SR-BI et CD36, qui ne causent pas d’infertilité chez les souris mâles était sans impact significatif sur le taux de cholestérol intratubulaire. Nous avons montré que l’invalidation génétique d’un transporteur sélectif ou d’une enzyme du métabolisme du cholestérol était accompagnée d’un ensemble de mécanismes de compensation visant à maintenir le taux de cholestérol libre aux niveaux semblables à ceux mesurés dans les fractions tissulaires de souris normales. Ensemble, nos résultats ont montré que l’expression des transporteurs sélectifs de cholestérol SR-BI, SR-BII, CD36 et ABCA1 variait en fonction de la spermatogenèse et du taux intratesticulaire du cholestérol suggérant leur contribution au maintien de l’homéostasie du cholestérol intratesticulaire. / The testis is made up of loops of convoluted seminiferous tubules surrounded by interstitial tissue composed of loose connective tissue containing Leydig cells that secrete testosterone into the bloodstream. The seminiferous tubules are lined with a stratified epithelium containing germ cells at various stages of development and the supporting Sertoli cells. Cholesterol is present in both compartments and is crucial for the development of germ cells, the fertility of spermatozoa as well as for testosterone production. In the interstitial compartment, approximately 40 % of the cholesterol used for the hormonal production is imported from blood lipoproteins HDL and LDL. In the seminiferous epithelium, Sertoli cells plays key role in the development and maintenance of spermatogenesis. Sertoli cells have the capacity to synthesize cholesterol from acetate in vitro, however, there is no evidence that they do so in vivo. In addition, there is a blood-testis barrier within the seminiferous tubules that prevents the free passage of several blood compounds including cholesterol. We tested the hypothesis that there are ways of blood cholesterol uptake, but also the intratubular cholesterol efflux that by-pass this barrier and contribute to the cholesterol homeostasis within the tubules. We compared expression patterns of the mRNA and proteins for selective cholesterol transporters SR-BI, SR-BII, CD36 and ABCA1 with those of free and esterified cholesterol during the spermatogenesis in normal mice during the postnatal development. To better appreciate the level of involvement of each receptor, we examined the effect of the deletion of the genes for an enzyme (HSL) or for cholesterol transporters (SR-BI, CD36 or NPC1) on the rate of free and esterified cholesterol in both compartments of the testis. At first, we worked out a new technique to separate the testes into interstitial tissue- (ITf) and seminiferous tubule-enriched fractions (STf) that has the advantage of allowing a more faithful detection of the phosphorylated and glycosylated forms of the proteins compared to existing techniques. Our results showed that the expression of SR-BI and CD36 was maximum in the ITf when mice completed their sexual maturity and reached the peak level of testosterone synthesis. In the seminiferous tubule-enriched fractions, the maximum level of SR-BI expression coincided with the highest level of esterified cholesterol during the development at 35 days, as the first wave of the spermatogenetic activity was completed. ABCA1 reached the highest expression level when cholesterol was high and reached the lowest when cholesterol was at its minimum, while the level of CD36 expression was maximal in the adult tubules as the rate of spermiation was the highest. The knockout of the HSL and NPC1, which renders the male mice infertile, was accompanied by the accumulation of free and esterified cholesterol in the seminiferous tubules. On the other hand, the knockout of SR-BI and CD36, linkes to infertility, did not affect the rate of intratubular cholesterol. Here we showed that genetic withdrawal of a cholesterol transporter or of an enzyme involved in cholesterol metabolism was compensated by other transporters or enzymes in order to maintain the level of free cholesterol similar to those measured in the tissue-enriched fractions of wild-type mice. Together, our results showed that the expression of the selective cholesterol transporters SR-BI, SR-BII, CD36 and ABCA1 varied according to the spermatogenesis and intratesticular cholesterol rate, thus suggesting their contribution to the preservation of the intratesticular cholesterol homeostasis.

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