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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.
31

Abastecimento de água e esgotamento sanitário da comunidade Água Branca do Cajari, Resex Cajari, AP: avaliação e formulação de alternativas / Water supply and sanitary sewer at Água Branca do Cajari: analyzes and alternatives planning

Rolim Neto, Raimundo de Moura 30 November 2016 (has links)
Ao longo dos anos a implementação das políticas de saneamento básico no Brasil foram evoluindo gradativamente, porém as metas de universalização não serão alcançadas até 2030. Os piores índices historicamente se concentram nas regiões norte e nordeste, sendo mais acentuados nas áreas rurais. O Amapá é o estado mais preservado do país, abrange em seu território diversas modalidades de áreas protegidas e comunidades tradicionais, dentre elas a comunidade Água Branca do Cajari, localizada na Reserva Extrativista do Rio Cajari, objeto de estudo desta Dissertação, que consistiu na formulação e avaliação de alternativas para suprir a demanda de água potável e ao encaminhamento seguro dos esgotos sanitários. Para o alcance dos objetivos, foram realizadas duas campanhas de campo, com o intuito de conhecer o perfil social, econômico e ambiental da comunidade, através da aplicação de questionários e observação in situ, avaliação da qualidade das águas destinadas ao consumo humano, através de análises físico-químicas e microbiológicas e estimativas da geração de esgoto. A proposição das alternativas foi feita a partir do dimensionamento e avaliação dos custos de instalação, operação e manutenção ao longo do horizonte de planejamento de 20 anos. Os orçamentos foram elaborados a partir de dados disponíveis na literatura técnica e a composição dos custos por pesquisas de preço e fontes oficiais como o SINAPI. Treze poços freáticos são utilizados pela população que reside na parte alta da comunidade, enquanto os que moram na parte baixa, retiram diretamente do rio, adicionam polímero que adquirem informalmente para a clarificação das águas, em média 95% da população afirma realizar a desinfecção com hipoclorito de sódio, sendo que 41,1% da população tem acesso ao mínimo estabelecido pela ONU e 7,6% abaixo do recomendado. Estavam em não conformidade, de acordo como o que estabelece a Portaria n° 2.914/2011 do Ministério da Saúde, 75% das amostras analisadas para o parâmetro pH, 62,5% para turbidez, 90% para coliformes totais/Escherichia coli. Cerca de 82,3% do esgoto séptico gerado é encaminhado a fossas negras, e 13% das unidades domiciliares não dispõe de banheiro. O custo total dos sistemas foi de: sistema de bombeamento fotovoltaico 430.644,97 R$ (0,18 R$/hab.dia); aproveitamento de água de chuva de 432.236,72 R$ (0,19 R$/hab.dia); filtro lento domiciliar 7.326.27 R$; sistema de desinfecção solar (SODIS) 9.768,54 R$ e para o tratamento de esgoto sanitário unifamiliar, fossas sépticas \"Imhoff\" e sumidouro 434.371,32 R$ ou 0,19 R$/hab.dia. Portanto, verificou-se que as alternativas avaliadas são viáveis economicamente e operacionalmente. A efetividade da implantação das tecnologias de tratamento de água e esgoto em comunidades isoladas ou de difícil acesso na Amazônia devem ser precedidas de estudos socioeconômicos, ambientais e culturais. / In the world, about 748 million of people do not have access to a potable water, more than 30% of the world population do not have appropriate installations and 1 million of people do their physical necessities in open areas, of theses, nine out ten are in rural areas. The policies about basic sanitation in Brazil gets better long of the years, but the marks for universalization cannot be touched until 2030. The indications get worst in north and northeast, especially in the countryside. Amapá is the most preserved state of Brazil, that has in its territory many spaces of protected areas and traditional communities, one of them is Àgua Branca do Cajarí, located in an extractive reserve, and is the focus of this issue, whose objective is propose and estimate better ways to get a high quality of water and sanitary wastewaters. To get better results, it was necessary to visit at these areas to know the community social, economic and environmental profile through questionnaires and in situ observation, beside doing physic-chemical and microbiological analyzes. The proposition of the best alternatives was made by starting from the estimative of installation and conservation along of 20 years, getting the present prizes. Those estimative were based on technical literature, prizes researched and official sources as SINAPI. Thirteen phreatic wells are used by people who live on the higher part of the community while people that live on the lowest part need to take water right from the river, put some polymer that is taken informally to clarify the water. About 95% of people say that use sodium hypochlorite in water, but just 41% has the least required by UNO and 7.6% is low from what is demanded. According with the governmental decree N. 2914/2011, 75% of the sample that were analyzed showed to the pH parameter; 62.5% for turbidity; 90% for total coliforms/ Escherichia coli. About 82.3% of the septic sewer created is sent to black cesspool and 13% of the houses do not have a bathroom. The total cost of the systems was about R$ 430,644.97 for a photoelectric system (0.18 R$/resident.day). The perforation and preservation of the wells were not considered; R$ 432,236.72 if use rain water (0.19 R$/resident.day). R$ 7,326.27 for slow domiciliary filter. R$ 9,768.54 for solar disinfection system and R$ 434,371.32 for unifamilial sanitary sewer treatment, septic tank \"imhoff\" and escape hole (0.19 R$/resident.day). Therefore, it was possible to see that the alternatives analyzed were economically and operationally possible. The implementation of water and sewer treatment technologies in isolated communities of by difficult access in Amazonia must be followed by socioeconomic, environmental and cultural studies.
32

História e arquitectura uma proposta de investigação-o Palácio dos Marqueses de Fronteira com situação exemplar da arquitectura residencial erudita em Portugal

Mesquita, Marieta Dá January 1992 (has links)
No description available.
33

American Bison Ecology and Bison-Cattle Interactions in an Isolated Montane Environment

Ranglack, Dustin H. 01 May 2014 (has links)
As bison are considered to be ecologically extinct, and negative interactions between bison and cattle are perceived to limit bison restoration and cattle production, I designed a series of studies to test for potential competition between bison (Bison bison) and cattle (Bos taurus) for forage on the Henry Mountains in southern Utah. These studies provide insight into key information gaps previously identified by the Utah Division of Wildlife Resources (UDWR), Bureau of Land Management, and the local grazing association. The results indicate that bison and cattle are not strong competitors for forage on the Henry Mountains. Jackrabbits (Lepus californicus) emerged as the strongest competitive threat to cattle, consuming more than twice the amount of forage consumed by bison. Further, bison habitat preferences did not match with cattle habitat needs as reported by a survey of the local ranching community. This suggests that negative impacts on cattle due to bison have been overstated. Still, any potential negative impacts of bison will be felt by a small group of local individuals. This prompted me to design a new management scheme, which has the potential to increase the number of bison on the Henry Mountains while also compensating local ranchers for reducing the number of cattle they graze in the area. This system should be mutually beneficial for the local ranching community and the UDWR, and easily implemented by taking advantage of the currently exiting conservation license program.
34

Effects of biaxial stretch on arteriolar function in vitro

Guo, Hong 02 June 2009 (has links)
Mounting evidence suggests that the normal biomechanical state of arteries may include a nearly equibiaxial intramural stress, and that arteries tend to undergo rapid and dramatic remodeling when perturbed from this normal state. Technical developments in the early 1980s and late 1990s enabled in vitro and ex vivo studies, respectively, of isolated perfused microvessels, and it is clear that they share many similarities in behavior with arteries. To date, however, there has been no systematic study of the effects of biaxial loading on the biomechanical behavior of arterioles. In this project, we describe a modification to a prior in vitro arteriole test system that allowed us to investigate the role of altered axial stretch on the passive, myogenic, and fully contracted biaxial behavior of isolated rat cremaster arterioles. We show that axial stretches from 85% to 110% of normal values induce modest changes in the measured circumferential and axial stress-stretch behavior and similarly in traditional measures of distensibility and myogenic index. Nevertheless, altered axial stretch has a dramatic affect on the biaxial state of stress and it appears that near equibiaxial stress occur at axial stretches larger than those used previously. Whereas this finding will not affect prior estimates of material and functional behavior, it may have important implications for the design of long-term ex vivo and in vivo studies wherein vessel growth and remodeling are critical.
35

Epidemiology and Genetics of Pituitary Tumors Épidémiologie et génétique des adénomes hypophysaires

Daly, Adrian Francis 18 January 2008 (has links)
Pour avoir une parfaite compréhension dune maladie, il est nécessaire den connaitre la fréquence, la symptomatologie et les causes dapparition. Dans le cas des adénomes hypophysaires, les données de la littérature concernant lépidémiologie de ces tumeurs sont contradictoires certaines études suggérant une haute prévalence, et dautres affirmant quelles sont plutôt rares. En parallèle, la compréhension de la physiopathologie des tumeurs endocrines telles que les adénomes hypophysaires a fait un bond en avant avec lavènement des techniques de biologie moléculaire. Pourtant, leur physiopathologie reste encore très floue. Le fait de se concentrer sur les causes familiales permet dapprocher plus efficacement les causes des tumeurs endocrines. Concernant les adénomes hypophysaires, mis à part les Néoplasies endocriniennes multiples de type I (MEN1) et le Complexe de Carney (CNC), le domaine des adénomes hypophysaires familiaux est peu compris. En effet, mise à part lacromégalie familiale, il ny a eu aucune étude sur dautres types dadénomes hypophysaires entrant dans le cadre familial. Les buts du travail contenu dans cette thèse étaient de décrire des aspects épidémiologiques et génétiques des adénomes hypophysaires. Tout dabord, nous avons étudié la discordance entre les taux de prévalence dadénomes hypophysaires provenant détudes radiologiques/autopsiques (les incidentalomes étant très fréquents) et dautre part ceux provenant de registres de cancers et plus rarement de données de population. Une étude intensive et complète de la prévalence des adénomes hypophysaires a été réalisée dans 3 régions géographiquement parfaitement délimitées dans la province de Liège. Dans cette étude qui a concerné une population de plus de 70 000 habitants, les adénomes hypophysaires diagnostiqués lont été en collaboration avec toute la communauté médicale de ces régions. Les données démographiques, cliniques, hormonales, radiologiques et pathologiques de tous les patients ont été confirmées de façon indépendante. A une date fixe, nous avons montré que les adénomes hypophysaires diagnostiqués suite à des symptômes cliniques surviennent avec une prévalence de 1 cas par 1064 habitants résidants dans les limites géographiques déterminées pour cette étude. Ces résultats montrent que la prévalence des adénomes hypophysaires évidents sur le plan clinique est de 3.5 à 5 fois plus haute que les estimations précédentes se rapportant à des populations ou des registres. Cela suggère que les adénomes hypophysaires significatifs sur le plan clinique surviennent assez fréquemment dans la pratique de tous les jours et ceci peut avoir des implications importantes sur la distribution des ressources de santé. Une étude épidémiologique internationale appliquant la même méthodologie est actuellement en cours. Létude des adénomes hypophysaires familiaux en-dehors du contexte de la polyendocrinopathie de type I ou du Complexe de Carney constitue la deuxième partie de ce travail. Jusquà présent, seule lacromégalie familiale avait été rapportée dans la littérature. Nous avons réalisé une étude internationale pour démontrer que tous les types dadénomes hypophysaires pouvaient survenir dans le cadre dune pathologie familiale différente de la polyendocrinopathie de type I et du complexe de Carney. La suspicion de cette pathologie est née à Liège au cours de la dernière décennie. Cette étude a démontré que les adénomes hypophysaires familiaux isolés (Familial Isolated Pituitary Adenoma ou FIPA) constituent 2% des adénomes hypophysaires et 64 familles FIPA ont été caractérisées cliniquement. Cette étude a démontré pour la première fois que tous les phénotypes dadénomes hypophysaires peuvent survenir dans les mêmes familles. Quelques familles montrent seulement un phénotype parmi les membres atteints (familles FIPA homogènes) et dautres familles montrent différents types de tumeurs chez les patients atteints (famille FIPA hétérogène). Dans les familles FIPA, les adénomes hypophysaires étaient plus agressifs et tendaient à survenir à un âge plus jeune que dans les cas sporadiques. Les familles FIPA montrent une grande proximité familiale entre les membres atteints suggérant un mode dominant de transmission. Les études ultérieures ont été réalisées sur les aspects génétiques et anatomo-pathologiques des adénomes hypophysaires et particulièrement ceux qui survenaient dans le contexte FIPA. La découverte dun gène nouveau aryl hydrocarbon receptor interacting protein (AIP), dont quelques mutations ont été associées avec des adénomes hypophysaires nous a conduit à entreprendre la première étude génétique dans les FIPA. Des mutations AIP ont été découvertes dans 15 % des familles et 50% des familles homogènes dacromégales dans le contexte FIPA. Ceci suggère que dautres gènes peuvent également être responsables du contexte FIPA. Dans les familles FIPA qui portent la mutation AIP, les tumeurs étaient plus importantes et survenaient à un âge plus jeune que dans les familles FIPA sans mutation AIP. Neuf nouvelles mutations AIP ont été identifiées, dont la majorité permet de prédire la perte du ligand ou de la région de AIP qui interagit avec son récepteur. Une mutation AIP dans les FIPA était associée avec différents types dadénomes hypophysaires incluant acromégalie, prolactinomes, adénomes mixtes à GH-prolactine et adénomes nonsécrétants. Nous avons également observé que la même mutation AIP pouvait être responsable de différents phénotypes dans 2 familles FIPA différentes. Un suivi détaillé dune famille FIPA avec mutation AIP a permis de montrer pour la première fois quune anomalie endocrinienne différente dune tumeur hypophysaire pouvait survenir chez des porteurs de mutation AIP (élévation de lIGF1). Une analyse détaillée de lADN germinal et somatique provenant dun grand groupe international européen dadénomes hypophysaires sporadiques (non familiaux) a montré que les mutations AIP surviennent rarement dans cette condition. En conclusion : Le travail entrepris a apporté une nouvelle compréhension de la vraie prévalence des adénomes hypophysaires diagnostiqués de façon clinique dans une population et il a permis de codifier et de caractériser le désordre FIPA, une nouvelle entité clinique qui représente une aire de recherche potentielle pour des études cliniques et génétiques impliquant la fonction de AIP et dautres gènes non encore identifiés. To have a full understanding of a disease, it is necessary to at least know how frequently it occurs, its clinical features and by what means it is caused. In the case of pituitary adenomas, data in the literature on the epidemiology of these tumors is conflicting, with some studies suggesting a high frequency, others that they occur rarely in the clinical setting. In parallel, the understanding of the pathophysiology of endocrine tumors like pituitary adenomas has advanced greatly with the advent of molecular genetic techniques. However, much remains unclear regarding pathophysiology. A valuable avenue for studying the causes of endocrine tumors has been to focus on the familial setting. With respect to pituitary adenomas, apart from multiple endocrine neoplasia type 1 (MEN1) and Carney complex (CNC), the field of familial pituitary tumors is poorly understood. Indeed, apart from familial acromegaly, there have been virtually no studies on other pituitary adenomas occurring in the familial setting. The aims of the work described in this thesis were based on addressing aspects of the epidemiology and genetics of pituitary tumors. Firstly, the disconnect between the prevalence rates for pituitary adenomas from autopsy/radiology studies (incidentalomas being very common) and cancer registries/population data (rare) was studied. An intensive, comprehensive, case-finding study of the prevalence of pituitary adenomas was performed in three tightly-defined geographical areas in the Province of Liège. In this study, which involved a population of more than 70,000 people, diagnosed pituitary adenomas were sought in collaboration with the entire group of community medical practitioners in the study areas, and the demographics and clinical, hormonal, radiological and pathological features of all patients were confirmed independently. On a fixed date, it was found that clinically diagnosed pituitary adenomas occurred with a prevalence of 1 case per 1064 individuals residing within the geographic boundaries of the study. These results report a clinical prevalence of pituitary adenomas that is 3.5 to 5 times higher than previous population/registry estimates. It suggests that clinically relevant pituitary adenomas occur frequently in the everyday clinical setting, which may have important implications for health resource allocations. Also, it is possible to undertake detailed, comprehensive, crosssectional epidemiological studies in well-defined geographic areas, and this methodology can be applied internationally Studying the familial occurrence of pituitary adenomas outside of MEN1 and CNC was the next aim of the work described. Up to this time, only the familial occurrence of acromegaly had been reported with any frequency in the literature. An international study was undertaken to assess whether isolated pituitary adenomas of all types could occur in the familial setting, a suspicion raised in Liège over the past decade. This study demonstrated that familial isolated pituitary adenomas (FIPA) occur in about 2% of pituitary adenoma populations, and 64 FIPA families were characterized clinically. The study demonstrated for the first time that all phenotypes of pituitary adenomas can occur together in families; some families exhibit only one phenotype among affected members (homogeneous FIPA kindreds), others have multiple tumor types among affected family members (heterogeneous FIPA). In FIPA families, pituitary tumors were more aggressive and tended to occur at a younger age than sporadic pituitary adenomas. FIPA families display a high degree of familiality, suggesting a dominant mode of inheritance. Subsequent studies were performed on the genetic and pathological features of pituitary adenomas, particularly those occurring as FIPA. The discovery of a novel gene, aryl hydrocarbon receptor interacting protein ( AIP), mutations in which were associated with isolated pituitary adenomas, led us to undertake the first such genetic studies in FIPA. AIP mutations account for a minority (15%) of FIPA families and 50% of familial acromegaly kindreds in FIPA. This suggests that other genetic causes for FIPA also exist. In AIP mutation carrying FIPA families, tumors were larger and had a younger age at diagnosis than non- AIP mutated FIPA kindreds. A series of 9 novel AIP mutations were identified, the majority of which led to predicted loss of vital ligand and receptor interacting regions of the AIP protein. AIP mutations in FIPA were associated with multiple pituitary adenoma types, including acromegaly, prolactinomas, mixed growth hormone/prolactin secreting adenomas and non-secreting tumors. It was also found that the same AIP mutation was responsible for different pituitary adenoma types in two separate FIPA families. A detailed follow-up study of an individual FIPA kindred with an AIP mutation found for the first time that non-pituitary tumor-associated endocrine abnormalities (elevated circulating insulin-like growth factor-1) occur in AIP mutation carriers. A detailed analysis of germline and somatic DNA from a large international European cohort of sporadic (non-familial) pituitary adenoma cases showed that AIP mutations occur rarely in this setting. In conclusion, the work undertaken has provided new understanding of the true prevalence of clinically-relevant pituitary adenomas in the population, in addition to codifying and characterizing FIPA, a new clinical entity that represents a potentially valuable area for genetic and clinical studies involving the function of AIP and other as yet unidentified associated genetic causes.
36

Effects of Lipolytic and Antilipolytic Agents on Glycerol and Free Fatty Acid Release from Isolated Adipocytes of Normal and Diabetic Rats

SAKAMOTO, NOBUO, KOH, NAOKI, FUKASAWA, HIDEO, KIMURA, MASAO, KAKUTA, HIRONOBU, HOTTA, NIGISHI, KAMEI, IZUMI 03 1900 (has links)
No description available.
37

Investigting the Cytoprotective Mechanisms of VIitamins B6 and B1 against Endogenous Toxin-induced Oxidative Stress

Mehta, Rhea 10 January 2012 (has links)
Recent epidemiological evidence suggests that many chronic health disorders in the developed world are associated with endogenous toxins formed from the Western diet. The Western diet, which encompasses calorie dense foods, processed foods and increased quantities of red meat, can cause intracellular oxidative stress through increased formation of reactive oxygen species(ROS) and reactive carbonyl species (RCS). A number of micronutrients have been investigated for their protective capacity in in vitro and in vivo models of oxidative stress. This thesis investigated the cytotoxic targets of Fenton-mediated ROS and RCS and the subsequent protective mechanisms of vitamins B1 (thiamin) or B6 (pyridoxal, pyridoxamine or pyridoxine) in an isolated rat hepatocyte model. The approach was to use an “accelerated cytotoxicity mechanism screening” technique (ACMS) to develop an in vitro cell system that mimicked in vivo tissue cytotoxicity. Using this technique, we investigated the protective mechanisms of vitamins B1 and/or B6 against the cytotoxic effects of two endogenous toxins associated with the Western diet: 1) RCS, as exemplified by glyoxal, a glucose/fructose autoxidation product and 2) biological ROS induced by exogenous iron. Firstly, we developed an understanding of the sequence of events contributing to glyoxal-induced oxidative stress, with a focus on protein carbonylation. Next, we determined the mechanisms by which carbonyl scavenging drugs (vitamin B6 included) protected against the intracellular targets of glyoxal-induced toxicity. Our results suggested that the agents used were cytoprotective by multiple mechanisms and glyoxal trapping was only observed when the agents were administered at concentrations equal to glyoxal. We also evaluated the protective capacity of vitamins B1 and B6 against iron-catalyzed cytotoxicity and found that hepatocytes could be rescued from protein and DNA damage when vitamins B1 or B6 were added up to one hour after treatment with iron. The vitamins also varied in their primary mechanisms of protection. Our improved understanding of Western diet-derived endogenous toxins enabled us to identify and prioritize the specific inhibitory mechanisms of vitamins B1 or B6. The ability to delay, inhibit or reverse toxicity using multi-functional B1 or B6 vitamins could prove useful as therapy to minimize oxidative stress in diet-induced chronic conditions.
38

Investigting the Cytoprotective Mechanisms of VIitamins B6 and B1 against Endogenous Toxin-induced Oxidative Stress

Mehta, Rhea 10 January 2012 (has links)
Recent epidemiological evidence suggests that many chronic health disorders in the developed world are associated with endogenous toxins formed from the Western diet. The Western diet, which encompasses calorie dense foods, processed foods and increased quantities of red meat, can cause intracellular oxidative stress through increased formation of reactive oxygen species(ROS) and reactive carbonyl species (RCS). A number of micronutrients have been investigated for their protective capacity in in vitro and in vivo models of oxidative stress. This thesis investigated the cytotoxic targets of Fenton-mediated ROS and RCS and the subsequent protective mechanisms of vitamins B1 (thiamin) or B6 (pyridoxal, pyridoxamine or pyridoxine) in an isolated rat hepatocyte model. The approach was to use an “accelerated cytotoxicity mechanism screening” technique (ACMS) to develop an in vitro cell system that mimicked in vivo tissue cytotoxicity. Using this technique, we investigated the protective mechanisms of vitamins B1 and/or B6 against the cytotoxic effects of two endogenous toxins associated with the Western diet: 1) RCS, as exemplified by glyoxal, a glucose/fructose autoxidation product and 2) biological ROS induced by exogenous iron. Firstly, we developed an understanding of the sequence of events contributing to glyoxal-induced oxidative stress, with a focus on protein carbonylation. Next, we determined the mechanisms by which carbonyl scavenging drugs (vitamin B6 included) protected against the intracellular targets of glyoxal-induced toxicity. Our results suggested that the agents used were cytoprotective by multiple mechanisms and glyoxal trapping was only observed when the agents were administered at concentrations equal to glyoxal. We also evaluated the protective capacity of vitamins B1 and B6 against iron-catalyzed cytotoxicity and found that hepatocytes could be rescued from protein and DNA damage when vitamins B1 or B6 were added up to one hour after treatment with iron. The vitamins also varied in their primary mechanisms of protection. Our improved understanding of Western diet-derived endogenous toxins enabled us to identify and prioritize the specific inhibitory mechanisms of vitamins B1 or B6. The ability to delay, inhibit or reverse toxicity using multi-functional B1 or B6 vitamins could prove useful as therapy to minimize oxidative stress in diet-induced chronic conditions.
39

Dynamic Simulation of a Hybrid Wind/Diesel Isolated Power System Using Artificial Neural Network

Jarjue, Edrissa 04 July 2011 (has links)
An isolated hybrid system comprised of a dispatchable and a non-dispatchable power generation sources, is proposed to supply the load of a remote village in the west coast region of The Gambia. The thesis presents an artificial neural network (ANN) based approach to tune the parameters of the frequency regulator in hybrid wind/diesel power system for isolated area power supply. The multi-layer feed-forward ANN with the error back-propagation training is employed to tune the frequency regulator in the simulation of hybrid system under different load and wind conditions. Using MATLAB/Simulink, dynamic simulations are performed to investigate the interaction between these two power sources for the load management, and the voltage and frequency behaviors during wind speed and load variations. Simulation results show that the wind turbine and the diesel generator can be operated suitably in parallel. During simulation, the frequency and voltage regulators used in the proposed hybrid system performed fairly well under wind speed variations and load changing conditions. A good frequency regulator interface, which is around 50Hz is observed for nearly the entire period of operation.
40

Effects of biaxial stretch on arteriolar function in vitro

Guo, Hong 02 June 2009 (has links)
Mounting evidence suggests that the normal biomechanical state of arteries may include a nearly equibiaxial intramural stress, and that arteries tend to undergo rapid and dramatic remodeling when perturbed from this normal state. Technical developments in the early 1980s and late 1990s enabled in vitro and ex vivo studies, respectively, of isolated perfused microvessels, and it is clear that they share many similarities in behavior with arteries. To date, however, there has been no systematic study of the effects of biaxial loading on the biomechanical behavior of arterioles. In this project, we describe a modification to a prior in vitro arteriole test system that allowed us to investigate the role of altered axial stretch on the passive, myogenic, and fully contracted biaxial behavior of isolated rat cremaster arterioles. We show that axial stretches from 85% to 110% of normal values induce modest changes in the measured circumferential and axial stress-stretch behavior and similarly in traditional measures of distensibility and myogenic index. Nevertheless, altered axial stretch has a dramatic affect on the biaxial state of stress and it appears that near equibiaxial stress occur at axial stretches larger than those used previously. Whereas this finding will not affect prior estimates of material and functional behavior, it may have important implications for the design of long-term ex vivo and in vivo studies wherein vessel growth and remodeling are critical.

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