• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 159
  • 108
  • 22
  • 19
  • 13
  • 10
  • 5
  • 5
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 462
  • 168
  • 156
  • 147
  • 76
  • 66
  • 52
  • 39
  • 37
  • 33
  • 30
  • 28
  • 28
  • 27
  • 26
  • 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.
291

In-depth characterization of the NS3:NS5 interaction within the West Nile virus replicase complex during positive strand RNA synthesis / Caractérisation détaillée de l’interaction entre NS3 et NS5 dans le complexe de réplication du virus du Nil occidental pendant la synthèse d’ARN de polarité positive

Brand, Carolin January 2017 (has links)
Les Flavivirus transmis par les moustiques comme le virus du Nil occidental, le virus de la dengue, le virus de la fièvre jaune, le virus de l’encéphalite japonaise et le virus Zika constituent des préoccupations croissantes de santé publique. Ils se sont répandus dans le monde au cours des dernières décennies, et les épidémies sont devenues plus fréquentes et plus sévères. Chaque année, des millions de personnes sont infectées et environ 50 000 patients décèdent d’infections à Flavivirus. Malgré les nombreux efforts de recherche, il n’y a actuellement aucun médicament antiviral spécifique disponible, et des nouvelles stratégies antivirales sont indispensables. Comprendre comment les Flavivirus fonctionnent au niveau moléculaire aidera à découvrir des nouvelles cibles pour l'intervention thérapeutique. Les Flavivirus ont un génome d'ARN simple brin de polarité positive qui code pour trois protéines structurales et huit protéines non structurales. Seules deux des huit protéines non structurales ont des activités enzymatiques. NS3 possède un domaine protéase et un domaine hélicase, et NS5 a un domaine méthyl- et guanylyltransférase et un domaine ARN polymérase ARN-dépendante. Ensemble, ils répliquent le génome viral. Ici, nous caractérisons l'interaction entre NS3 et NS5 dans le complexe de réplication du virus du Nil occidental pendant la synthèse d’ARN de polarité positive. Un modèle d'interaction comprenant NS3, NS5 et l’ARN viral a été développé basé sur des structures cristallines connues ainsi que des activités enzymatiques des deux protéines individuelles, et ce modèle a été soumis à des simulations de dynamique moléculaire. Les interactions potentielles entre les protéines NS3 et NS5 ont été identifiées. Les résidus impliqués dans ces interactions ont été mutés dans un réplicon du virus du Nil occidental et les effets de ces mutations sur la réplication virale ont été évalués. Une région particulière à la surface de la protéine NS3 a été identifiée comme étant cruciale pour la réplication virale, très probablement parce qu'elle interagit avec NS5. Cette région pourrait être une cible attrayante pour la recherche de composés qui pourraient interférer avec l'interaction entre NS3 et NS5 et donc posséder un potentiel antiviral intéressant. / Abstract : Mosquito-borne Flaviviruses like West Nile virus, Dengue virus, Yellow Fever virus, Japanese encephalitis virus, and Zika virus are increasing public health concerns. They have spread globally during the past decades, and outbreaks have recently become more frequent and more severe. Every year, millions of people are infected, and approximately 50,000 patients die from Flavivirus infections. Despite extensive research efforts, there are currently no specific antiviral drugs available, and new antiviral strategies are greatly needed. Understanding how Flaviviruses work on a molecular level will help in uncovering new points for therapeutic intervention. Flaviviruses have a single-stranded RNA genome of positive polarity that encodes three structural and eight non-structural proteins. Only two of the eight non-structural proteins have enzymatic activities. NS3 has an N-terminal protease domain and a C-terminal helicase domain, and NS5 has an N-terminal capping enzyme domain and a C-terminal RNA-dependent RNA polymerase domain. Together, they replicate the viral genome. Here we characterize the NS3:NS5 interaction within the West Nile virus RNA replicase complex during positive strand synthesis. An interaction model including NS3, NS5 and viral RNA was developed based on the known crystal structures as well as enzymatic activities of the two individual proteins, and this model was subjected to molecular dynamics simulations. Potential interactions between the NS3 and NS5 proteins were identified. Residues involved in these interactions were mutated in a West Nile virus replicon, and the effects of these mutations on viral replication were evaluated. One particular region on the surface of the NS3 protein was identified to be crucial for viral replication, most likely because it mediates the interaction with NS5. This region might be an attractive target for the search of compounds that could interfere with the NS3:NS5 interaction and therefore possess an interesting antiviral potential.
292

A 'Seat at the Table': Exploring the relationship between pluralist structures and involvement in decision-making—The Case of the Nile Basin Initiative

Okoth, Simon 30 November 2009 (has links)
The goal of this study was to explore the relationship between pluralist structures and involvement in decision-making of the Nile Basin Initiative (NBI). To establish this relationship the study asked two primary questions: What are the characteristics of power structures of the NBI as they relate to stakeholder involvement in Ethiopia? For those not involved in the decision-making process, what constraints prevent them from getting a ‘seat at the table’?” Two secondary questions were also asked: Do the power structure characteristics in Ethiopia relate to pluralism and, if so, how? To what extent are conditions in Ethiopia compatible with the prerequisites of pluralism? The study focused on one issue-area, the Water Resources Planning and Management Project. Qualitative data were collected primarily from NGOs in Ethiopia during the month of December, 2008. Background information was collected in Entebbe, Uganda, the home to the NBI Secretariat. Data sources included in-depth key informant interviews (n=30), archival, geographical, historical, and scientific accounts. The findings show that 1) the characteristics of power structures of the Nile Basin Initiative in Ethiopia are both pluralistic and elitist; 2) the level of involvement in the Water Resources Planning and Management Project by nongovernmental stakeholders is low; 3) the framework for involvement is limited and restricted to invitations to selected meetings in which the role of the NGOs is that of the observer; 4) political factors are the leading constraints to involvement, followed by lack of capacity of the NGOs and the NBI, structural limitations, and lack of information and awareness. The study concludes that, even though there is consistent theoretical link between pluralist structures and stakeholder involvement, the mere presence of pluralist structures does not guarantee involvement. It all depends on how well those structures function. The findings thus leads this study to hypothesize that the pluralist structures and elite power structures exist side by side, at least in the context of Ethiopia. Through the pluralist structures, organized groups are formally recognized while the elite power structures determine the process and who makes the decisions.
293

Spatio-temporal patterns of infectious disease vectors in the eastern Smoky Hills, Kansas

Ganser, Claudia January 1900 (has links)
Master of Science / Department of Biology / Samantha M. Wisely / Nearly 30% of emerging infectious diseases are caused by vector-borne pathogens with wildlife origins, posing a risk for public health, livestock, and wildlife species of conservation concern. Understanding the spatial patterns of exposure to dipteran vectors and their associated pathogens is critical for epidemiological research to target prevention and control of vector-borne infectious diseases. In recent years, Western Equine encephalitis, St. Louis encephalitis, West Nile Virus encephalitis and avian malaria have not only been a public health concern but also a conservation concern, specifically the conservation of grassland nesting birds. Although the central Great Plains is the most specious region for grassland nesting birds, their role in the enzootic (primary) amplification cycle of infectious diseases may lead to further population depressions, and could potentially result in spill-over events to humans and livestock. The goals of my thesis were 1) to identify the underlying causes of spatio-temporal abundance patterns of mosquito vectors within the grasslands of the eastern Smoky Hills, and 2) to create probabilistic distributions of functional disease vectors, to evaluate disease risk in Greater Prairie-chicken (Tympanuchus cupido, surrogate species for other grassland nesting birds). First, I found that temporal dynamics in mosquito abundances were explained by maximum and minimum temperature indices. Spatial dynamics in mosquito abundances were best explained by environmental variables, such as curvature, TWI (Topographic Wetness Index), distance to woodland and distance to road. Second, the overall predictive power of the ecological niche models of important vector species in the grasslands of the Smoky Hills was better than random predictions, indicating that the most important predictor variables in their distribution were: distance to water, TWI, AASHTO (soil particle size distribution), and mean temperature during the coldest quarter. Furthermore, the spatial analysis indicated that Greater Prairie-chicken nest in areas with a higher probability of vector occurrence than other potentially available habitats within the grasslands. However, I failed to detect a significant difference in the probability of vector occurrence at nest of infected versus uninfected females. Understanding the distribution and abundance patterns of vectors of infectious diseases can provide important insights for wildlife conservation as well as public health management.
294

Níveis de cálcio e fósforo disponíveis no desempenho reprodutiv e mineralização possea da tilápia-do-Nilo /

Carvalho, Pedro Luiz Pucci Figueiredo de. January 2013 (has links)
Orientador: Luiz Edivaldo Pezzato / Coorientador: Pedro de Magalhães Padilha / Banca: João Batista Kochenborge / Banca: Hamilton Hisano / Resumo: A tilapicultura é a atividade aquícola que mais cresce no mundo, aumentando a demanda por larvas e alevinos a cada ano. Isso faz com que o desempenho reprodutivo assuma papel fundamental para o sucesso dessa atividade. O presente estudo foi conduzido com o objetivo de avaliar teores de cálcio e fósforo disponível em rações para fêmeas reprodutoras de tilápia-do-nilo, por meio de suas respostas de desempenho produtivo e mineralização óssea. Foram confeccionadas quatro rações isoproteicas e isoenergéticas (32,5% PD e 3300 kcal ED kg-1 ração), com níveis de 0,21-0,14%; 0,37-0,25%, 0,75-0,50%, 1,50-1,00% de Ca e Pdisp, respectivamente, mantendo relação Ca e P de 1,50:1,00. Foram utilizadas 36 fêmeas e 12 machos reprodutores (peso médio de 150 g), distribuídos em quatro aquários de 1000 litros de capacidade útil, na densidade de 9 fêmeas/3 machos/aquário, alimentados duas vezes ao dia, por 180 dias. Não foram observadas diferenças significativas (P>0,05) nos parâmetros morfométricos dos ovos, teores de cálcio e fósforo dos mesmos, desempenho zootécnico e reprodutivo das matrizes, exceto pela taxa média de eclosão de ovos, beneficiada pela dieta com nível mais elevado de Ca e Pdisp. Os parâmetros de mineralização óssea foram afetados pelos níveis de minerais nas dietas (P<0,05). Nos machos, o volume do crânio, densitometria das vértebras, crânio e total, além dos teores de Ca e P nos ossos foram significativamente maiores nos peixes do tratamento com maior nível de inclusão desses minerais. Nas fêmeas, o volume das vértebras, crânio e total, assim como a densitometria do crânio e os teores de Ca e P nos ossos foram significativamente maiores nos animais que receberam a dieta com maiores níveis desses minerais. Conclui-se que níveis ... / Abstract: Tilápia culture is growing rapidly all over the world, thus the demand for larvae and fingerlings increases every year, causing the reproductive performance takes key role in the success of this activity. The present study was conducted to evaluate calcium and available phosphorus in diets for reproductive female Nile tilápia, through their reproductive performance and bone mineralization. Four isonitrogenous and isoenergetic (32.5% PD and 3300 kcal kg-1) diets were formulated, with levels of 0.21-0.14%, 0.375-0.25%, 0.75-0.50%, 1.50-1.00% of calcium (Ca) and disponible phosphorus (Pdisp), respectively. 36 females and 12 males (average weight 150 g) were distributed in four tanks with 1000 liters of capacity, in a density of 9 females and 3 males per aquarium, were fed twice a day for 180 days. There were no significant differences (P >0.05) in morphometric parameters, calcium and phosphorus of the eggs. Egg hatchability were benefited from the diet with the highest level of Ca and Pdisp. The parameters of bone mineralization were affected by the levels of minerals in the diet (P<0,05). In males, the volume of the skull, densitometry of the spine, skull and total body, besides the content of Ca and P in bone, were significantly higher at higher inclusion levels of these minerals. In females, the volume of the vertebrae, skull and total body, as well as the density of the skull and the Ca and P in bone were significantly higher in animals fed the diet with higher levels of these minerals. We conclude that levels of 1.50-1.00% Ca and Pdisp, respectively, in the diet of Nile tilápia broodstock, provides better bone mineralization and higher rates of egg hatchability / Mestre
295

Produtividade e economicidade da tilapicultura em gaiolas na região sudoeste do estado de São Paulo: estudos de casos. / Productivity and economy of tilapicultura in cages in são paulo state south-west region: cases.

Conte, Luciane 17 January 2003 (has links)
Por causa da carência de dados sobre a produtividade de tilápias em tanques-rede em escala comercial, produtores e empresários rurais relutam em investir neste sistema de produção. Este estudo objetivou determinar as funções de produção da tilápia do Nilo em tanques-rede; a biomassa econômica de sistemas de produção comercial de tilápias em tanques-rede de diferentes volumes (300 a 400 peixes/m 3 e 500 a 600 peixes/m 3 ); e analisar a influência das condições ambientais no desempenho dos peixes em tanques-rede. Foram estudados 2 casos na região Sudoeste do Estado de São Paulo: (1) represa do Chapadão, 3,3 ha de espelho d’água e profundidade média de 4,00 m, onde foram instaladas nove gaiolas, totalizando 94,50 m 3 de volume útil de produção; e (2) represa da Colônia Nova, 8,8 ha de espelho d'água e profundidade média de 2,60 m, que alojou 27 gaiolas com volume útil total de 235,70 m 3 , ambas localizadas na Usina Paredão, Oriente, SP. De setembro de 2001 a abril de 2002, foram monitorados diariamente o consumo de ração, a mortalidade de cada gaiola e a temperatura da água das represas nos horários das alimentações; pH, oxigênio dissolvido e transparência pelo disco de Secchi foram monitorados quinzenalmente. Foram realizadas biometrias mensais nas gaiolas das duas represas, compreendendo 3% do lote de peixes de cada gaiola. Os peixes foram alimentados com ração extrusada comercial com 32% de proteína bruta, 3 vezes ao dia (09h00m, 13h00m e 17h00m), 7 dias por semana. A taxa de alimentação foi ajustada com base nas biometrias e mortalidade de cada gaiola. Os dados de desempenho foram analisados por análise de variância e regressão. Para a determinação das funções de produção a partir dos dados de campo, foram utilizadas as funções Logística e de Mitscherlich. Não houve diferença de desempenho em relação à biomassa acumulada e peso médio unitário em função do tempo, na densidade de 300 a 400 peixes/m 3, para ambas as represas (P<0,05), possivelmente porque os dois ambientes apresentaram variações dos parâmetros de qualidade de água muito similares e dentro dos limites aceitáveis para a espécie considerada. A densidade de 500 a 600 peixes/m 3 apresentou maior biomassa acumulada e maior eficiência alimentar que a densidade de 300 a 400 peixes/m 3. Não houve diferença significativa (P<0,05) entre o peso médio unitário dos peixes nas duas densidades, mostrando que o aumento na densidade de estocagem não influenciou o crescimento individual dos peixes. Para a densidade de 500 a 600 peixes/m 3, a biomassa que maximizou a lucratividade da produção (biomassa econômica - BE) foi 145 kg/m 3, ponto em que os peixes devem ser despescados ou remanejados. Para a densidade de 300 a 400 peixes/m 3 , a BE foi de 121 kg/m 3. Para a obtenção de peixes com peso médio unitário de 283g, considerando a BE de 145 kg/m 3 , a densidade de 500 a 600 peixes/m 3 possibilitou otimização do espaço e tempo de produção, melhor eficiência alimentar, maior produção por m 3 de tanque-rede, sendo portanto mais rentável economicamente que a de 300 a 400 peixes/m 3. / Cage farming of tilapia is an excellent alternative to utilize lakes, dams and reservoirs inadequate to conventional aquaculture. Low investment on cage or pond farming of tilapia is credited to the lack of reliable production and economical data for commercial scale farming. This study aimed to determine the production functions of Nile tilapia Oreochromis niloticus in cages; the economic biomass at stocking densities of 300-400 fish/m 3 and 500-600 fish/m 3 commercially produced tilapia in cages of different volumes; and the influence of environmental conditions in fish performance in cages. Two cases in São Paulo State south-west region were studied: (1) reservoir Chapadão (Usina Paredão , Oriente, SP), 3.3 ha of surface area, 4.00 m deep, with 9, 94.50 m 3 cages; and (2) reservoir Colônia Nova (Usina Paredão, Oriente, SP), 8.8 ha of surface area, 2.60 m deep, with 27, 235.70 m 3 cages. Feed intake, survival rate and water temperature were monitored daily during scheduled feedings from September 2001 - April 2002. Dissolved oxygen, pH and transparency of water were monitored each 15 days. Fish growth was evaluated by measuring and weighing 3% of fish of each cage. Caged tilapia fed on commercial, floating pellets (32% crude protein) at 0900, 1300 and 1700 h, 7 days for a week. Feeding rate was adjusted based on sample weight and survival rate. Data were analyzed statistically by ANOVA and regression analysis. The Logistic and Mitscherlich functions were chosen to elaborate the production functions. Carrying capacity of both stocking densities 300-400 fish/m 3 and 500-600 fish/m 3 was 200 kg/m 3. No differences were observed in fish performance regarding accumulated biomass and individual average weight over time between both reservoirs for the stocking density of 300-400 fish/m 3 . The stocking density of 500-600 fish/m 3 presented larger accumulated biomass and better feeding efficiency than the stocking density of 300-400 fish/m 3. No significant differences between individual average weight of fish of both densities were observed (P<0.05), meaning that increasing stocking density didn't influence the individual growth of fish. The biomass that maximized the profit to the stocking density of 500-600 fish/m 3 was 145 kg/m 3. Economic biomass (BE) for stocking density of 300-400 fish/m 3 , was 121 kg/m 3. This density had worse feed conversion than 500-600 fish/m 3. Stocking density of 500-600 fish/m 3 , up to individual average weight of 283 g, present many advantages: optimization of space and production time, better feed efficiency, higher fish production per m 3 of cages, and is more profitable than 300-400 fish/m 3.
296

Evaluation of Prebiotic and Probiotic as Functional Feed Additives on Physiological and Immunological Parameters of Nile Tilapia, Oreochromis niloticus

Kenneth E Saillant (6611177) 10 June 2019 (has links)
Experiments were conducted to evaluate the ability of prebiotic and probiotic supplementation of commercial fish feed to improve the physiological, immunological, and growth responses of stressed Nile tilapia. To investigate these objectives, tilapia were divided in two major groups: control fish (fed regular commercial feed) and stressed fish (induced by dietary cortisol supplemented to regular commercial feed). Stressed fish were further divided into three sub-groups: stressed fish fed regular feed, stressed fish fed probiotic-supplemented feed, and stressed fish fed a mixture of prebiotic and probiotic supplemented feed. Fish were maintained and tested over an eight-week long experimental period. A variety of physiological, immunological, and growth parameters were measured over the course of the experimental period. These parameters include: serum cortisol, blood glucose, plasma protein, packed cell volume, hepato-somatic index (HSI), spleen-somatic index (SSI), lysozyme activity, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), length gain, weight gain, length gain, and condition factor (K). The results of this study does not support the use of these specific prebiotic and probiotic as functional feed additives in Nile tilapia at the levels tested in this study. Further research is needed to determine which probiotic species are best suited for use in Nile tilapia and which prebiotic, when used in combination, will allow these probiotics to have maximum effect.
297

Dieta, aspectos metabólicos e parasitológicos de Oreochromis niloticus cultivados e silvestres, no reservatório de Ilha Solteira, rio Grande, SP

Pagliarini, Cibele Diogo. January 2019 (has links)
Orientador: Igor Paiva Ramos / Resumo: Oreochomis niloticus é uma espécie de peixe não-nativa invasora no Brasil, e atualmente, a mais produzida e consumida no país. Contudo, os efeitos/influências ambientais deste sistema de cultivo ainda não estão satisfatoriamente elucidados. Além disso, os escapes são problemas recorrentes nas estações de criação. Assim, o objetivo deste trabalho foi caracterizar a composição da dieta, fatores metabólicos musculares e aspectos parasitológicos de O. niloticus silvestres e cultivados, além de avaliar a sobreposição de nicho trófico desta espécie com a ictiofauna silvestres que habita o entorno dos tanques-rede em uma piscicultura no reservatório de Ilha Solteira, rio Grande, SP. Realizou-se duas coletas de O. niloticus e de outras 17 espécies silvestres, uma no mês de janeiro e outra em julho de 2017. Os espécimes foram eutanasiados, medidos (cm) e pesados (g). Em campo, realizou-se raspagem da pele de O. niloticus com lâminas histológicas para avaliar a presença de ectoparasitas. Todos os peixes foram necropsiados para retirada dos estômagos, fixados e analisados posteriormente. Apenas dos exemplares de O. niloticus foram retiradas amostras de tecido muscular para análises metabólicas e os demais órgãos para avaliação de endoparasitas. A carcaça foi filetada e o tecido muscular foi analisado em mesa de luz para inspeção macroscópica de parasitas encistados. Para todas as análises estatísticas foram consideradas a variação espaço/temporal [espaço (local) = exemplares oriundos do... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Oreochomis niloticus is a non-native invasive fish in Brazil, and currently the most produced and consumed fish in the country. However, the environmental effects/influences of this production system are poorly elucidated. In addition, accidental releases are recurring problems in fish farms. Thus, the aims of this study were to characterize the composition of the diet, muscle metabolic factors and parasitological aspects of wild (from accidental release) and cultivated O. niloticus, besides evaluating the overlap of trophic niche of this species with the wild icthyofauna that inhabits the environment close to the cage fish farm in the Ilha Solteira reservoir, rio Grande, SP. Two samples of O. niloticus and 17 other wild species were taken, during the rainy period (in December 2016) and the dry period (in July 2017). The specimens were euthanized, measured (cm) and weighed (g). In the field, specimens of O. niloticus were submitted to skin scraping to collect the mucus on slides to evaluate the presence of ectoparasites. All fish were necropsied to remove the organs (stomach, intestine, liver, mesentery, kidney, eyes and heart) to parasitological procedures. The stomachs were fixed and the parasitological and diet analysis were performd concomitante.The muscles tissues of O. niloticus specimens were removed, and samples were used in the metabolic analysis, and a part of the material was filleted and submmited to a macroscopic inspection in the candling table, to looking for e... (Complete abstract click electronic access below) / Mestre
298

Aproveitamento do resíduo do beneficiamento da Tilápia do Nilo (Oreochromis niloticus) para obtenção de silagem e óleo como subprodutos. / Utilization of fish waste from the processing of nile tilapia (Oreochromis niloticus) to obtain fish silage and fish oil as by-products.

Arruda, Lia Ferraz de 27 August 2004 (has links)
Um terço da captura mundial de pescado não é empregada para o consumo direto na alimentação humana, seguindo para elaboração de rações ou é desperdiçada como resíduo. O ideal seria utilizar a matéria-prima em toda a sua extensão e recuperar os subprodutos, evitando a própria formação do resíduo. Com os objetivos de aumentar a receita e a eficiência de produção da indústria e, conseqüentemente, minimizar os problemas ambientais e de sanidade, provenientes do resíduo de pescado, procedeu-se à elaboração da silagem química do resíduo de beneficiamento da tilápia. A tilápia do Nilo (Oreochromis niloticus) é hoje a espécie mais popular no Brasil. A tilápia é cultivada em 22 estados brasileiros e a sua produção anual está entre 30 e 40 mil t. A tilápia foi uma das primeiras espécies oriundas da aqüicultura a ser beneficiada, sendo atualmente comercializada na forma de filés congelados, tecnologia emergente, porém com rendimento de cerca de 30%. Com isso, há necessidade de se transformar o resíduo gerado com o beneficiamento do filé em subprodutos, diminuindo o impacto ambiental. A silagem foi elaborada após homogeneização em cutter e acidificação da biomassa com 3% de ácido fórmico: propiônico, 1:1, adição do antioxidante BHT e manutenção do pH ao redor de 4,0. Foram realizadas análises para determinação da umidade, proteína, lipídios e cinza. Os aminoácidos foram examinados em auto analisador após hidrólise ácida, à exceção do triptofano determinado por colorimetria. A silagem de tilápias apresentou teores semelhantes ou maiores aos preconizados pelo padrão da FAO para todos os aminoácidos essenciais, com exceção do triptofano. Os valores mais elevados encontrados foram para o ácido glutâmico, leucina e lisina. Os resultados indicam uma possível utilização da silagem, preparada a partir do resíduo de processamento da Tilápia-do-Nilo, como fonte proteíca na formulação de ração para peixes. Entretanto, para o aproveitamento da silagem é necessário que se estabeleçam técnicas para remoção do óleo presente com a finalidade de aumentar a estabilidade do produto e seu valor comercial. A oxidação dos lipídios presentes pode causar a formação de peróxidos que podem complexar as proteínas com conseqüente destruição dos aminoácidos. O presente trabalho buscou, também, estabelecer a melhor via de extração do óleo presente na silagem ácida de tilápia do Nilo (Oreochromis niloticus), bem como caracterizar o óleo obtido. A fração lipídica foi extraída por três métodos de extração, a saber, centrifugação (3500 × G/30 min), Soxhlet (AOAC,1990) e Bligh & Dyer (1969). Os resultados para rendimento e índice de peróxido foram, respectivamente, 65,53% e 0,00 mEq/1000g de O2, 44,27% e 25,00 mEq/1000g de O2, 46,87% e 0,00 mEq/1000g de O2. O óleo de tilápia contém, em mg/100g, 28,60; 16,30 e 3,10 dos ácidos oléico, linoléico e linolênico, respectivamente. A centrifugação demonstrou ser a melhor metodologia de extração, por preservar as características físico-químicas do óleo e propiciar maior rendimento. O conteúdo de lipídios na silagem de tilápias, com base na matéria úmida é de 3,99 g/100g, com a retirada da fração lipídica através da centrifugação, restou na amostra apenas 1,54 g/100g de lipídios, o que é considerado um nível aceitável para inclusão em rações para animais. / One third of the world fishing produce is not directly applied in human consumption. Instead, it is used in the elaboration of feed or wasted as residue. It would be ideal to use the raw material thoroughly and to recover by-products, preventing the generation of residues. With the objectives of increasing the income and the production of the industry, as well as minimizing environmental and health problems from fish residues, chemical silage from Tilapia processing residues was produced. The Nile tilapia (Oreochromis niloticus) is the most popular species in Brazil today. Tilapia is cultivated in 22 Brazilian states and its annual production is between 30 and 40 thousand tons. Tilapia was one of the first aquaculture species to be processed after harvesting, being currently commercialized in the form of frozen fillets, however, with a yield of about 30%. Thus, there is a need for transforming the residues generated by the fillet processing into by-products, minimizing the environmental impact. The silage was elaborated after cutter-homogenization and acidification of the biomass with 3% formic acid: propionic, 1:1, addition of antioxidant BHT and maintenance of pH at about 4.0. Analyses for the determination of the moisture, protein, lipids and ash were carried out. The amino acids were examined in an auto analyzer after acid hydrolysis, except for the triptophane which was determined through colorimetry. The tilapia silage presented contents that were similar to or higher than the FAO standards for all essential amino acids, except for the triptophane. The highest values found were for lysine and leucine. The results indicate a possible use of the silage prepared from the Nile tilapia processing residue as a proteic source in the manufacturing of fish feed. However For the use of the silage, oil-removing techniques are necessary in order to increase the stability of the product as well as its commercial value. Lipid oxidation may cause peroxide formation, which can produce complex proteins with a consequent destruction of amino acids. The present work tried to determine the best form of extracting the oil from the acid silage of Nile tilapia (Oreochromis niloticus) and to caracterize the silage oil. The lipid fraction was extracted by three extraction methods: centrifugation (3500 × G·30 min-1), Soxhlet (AOAC, 1990) and Bligh & Dyer (1969). The results for yield and peroxide value were, respectively, 65.53% and 0.00 mEq·1000g-1 of O2, 44.27% and 25.00 mEq·1000g-1of O2, 46.87% and 0.00 mEq·1000g-1 of O2. The lipid fraction showed 28,60; 16,30 and 3,10mg·1000g-1 of oleic, linoleic and linolenic acids, respectively. Centrifugation proved to be the best extraction methodology due to the preservation of the physical-chemical characteristics of the oil and greater yield. The lipid content of the tilapia silage, on a fresh matter basis, was 3.99g·100g-1. With the removal of the lipid fraction by centrifugation, only 1.54 g·100g-1of lipids could be found in the sample, which is considered an acceptable level for its inclusion in animal feed.
299

Approche chronologique, territoriale et sociologique de la céramique préhistorique de Nubie (Mésolithique, Néolithique et Néolithique tardif, 2e-3e cataractes du Nil, Soudan) / Chronological, Territorial and Sociological Approach of the Prehistoric Pottery of Nubia (Mesolithic, Neolithic and Late Neolithic, 2nd-3rd cataracts of the Nile, Sudan)

Delattre, Hélène 26 November 2016 (has links)
Cette étude du matériel céramique provenant de la région située entre les 2e et 3e cataractes du Nil est anthropologique. Elle consiste dans un premier temps à établir un outil de classification permettant le diagnostic des sites dans lesquels la poterie a été mise au jour. Ce travail préliminaire conduit ensuite à aborder le corpus selon trois axes. Le premier est chronologique et aboutit à la construction de la séquence de l'occupation de Haute Nubie, et ce en trois étapes, céramique, culturelle et périodique. Le deuxième axe est territorial et remplit deux objectifs : d'abord déterminer les frontières des faciès et des cultures de la vallée du Nil moyen ; ensuite appréhender les dynamiques à l'échelle de l'Afrique du nord-est – qu'il s'agisse de diffusions d'objets et d'idées, de migrations de populations ou d'échanges marchands. La dernière partie est consacrée à l'approfondissement de quelques faits sociaux : d'abord l'imbrication du stockage, de la sédentarité et de la hiérarchie, ensuite le dépôt de mobilier dans les tombes, et enfin deux systèmes de croyances, en lien avec le monde animal et l'univers minéral. / This study of the pottery which was discovered in the region situated between the 2nd and the 3rd cataracts of the Nile is an anthropological study. First, it consists in building a classification tool which would help to diagnose the sites where the pottery was unearthed. This preliminary work leads to approach the corpus in three ways. First, the sequence of the occupation of Upper Nubia is built, in three stages: ceramics, cultures and periods. The second area of research is territorial and has two aims: to determine the boundaries of the facies and the cultures of the Middle Nile Valley, and to comprehend the dynamics across the Northeastern Africa – circulation of objects and ideas, migrations of populations, marketable exchanges. The last part is devoted to the study of some social facts: first, the interweaving of storage, sedentarity and hierarchy, then the deposition of artefacts in graves, and finally two systems of beliefs, in connection with the animal and the mineral world.
300

Seismic geomechanics of mud volcanoes

Gulmammadov, Rashad January 2017 (has links)
Mud volcanoes constitute an important component of petroliferous basins and their understanding is essential for successful exploration and development of hydrocarbon fields. They occur in both extensional and compressive tectonic settings, along with passive and active continental margins. Although extensive research exists on the geochemistry, geomorphology and stratigraphic evolution of these localized fluid flow structures, little is known about their geomechanical characteristics. This research investigates the geomechanics of mud volcanoes from the South Caspian Basin and West Nile Delta. This is achieved by establishing a workflow for geomechanical assessment of mud volcanoes using a P-wave velocity dataset from across the mud volcano within the offshore South Caspian Basin. This objective is developed further with the availability of seismic and wellbore data from around the Giza mud volcano, offshore West Nile Delta. Preliminary results of this study from the South Caspian Basin enable confidence in estimating the realistic magnitudes of elastic rock properties, stresses and fluid pressures from empirical and analytical correlations. Moreover, analysis of the variations in fluid pressures allow the fluid flow models around the mud volcano to be constrained and their gradients provide preliminary estimates of the drilling window. Structural and stratigraphic analysis around the Giza mud volcano offers insight into the formation of the mud volcano during the Quaternary and how the fault networks on the hanging wall of the arcuate tectonic fault have acted as conduits for primarily the pre-Pliocene fluids exploiting the areas of weakness along the hanging wall of the fault by entraining the Pliocene sediments. Fluid pressure evaluation reveals small overpressures caused by disequilibrium compaction. Further analysis offers insight into the critical fluid pressures that control fault movement, the stresses responsible for rock deformation around the wellbore and the width of the drilling window constrained by the fracturing of the strata. Analysis presented here provides details on the geomechanical significance of mud volcano environments, with implications for engineering practices. Overall, findings contribute to a systematic understanding of mud volcano settings not only from a field exploration and development point of view, but also at a wider scale for basin analysis and relatively small scale for play analysis.

Page generated in 0.0668 seconds