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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.
21

Influência de variáveis de paisagem sobre a riqueza e composição de assembleias de peixes em lagoas costeiras no sul do Brasil

Guimarães, Taís de Fátima Ramos January 2013 (has links)
Lagoas costeiras são ecossistemas dinâmicos caracterizados por uma alta biodiversidade, e podem ser vistos como manchas de hábitats na paisagem. Potencialmente, as características das comunidades em lagoas podem ser explicadas por teorias ecológicas (Biogeografia de Ilhas e Ecologia de Metacomunidades), onde o grau de isolamento e a heterogeneidade do hábitat em escala da paisagem são fatores importantes na determinação da comunidade. O objetivo deste trabalho foi verificar a influência destes fatores sobre diferentes descritores da comunidade (abundância, diversidade alfa e beta) de peixes em lagoas costeiras, utilizando métricas de paisagem. A área de estudo localiza-se no sistema do rio Tramandaí, RS (50,14°O; 29,98°S), possui 41 lagoas com diferentes graus de conexão e comunica-se com o mar através do estuário de Tramandaí. As variáveis de paisagem foram obtidas através de sistemas de informação geográfica (imagens Spot e Landsat-TM5) e foram divididas entre variáveis estruturais (área, forma, distância do mar, coeficiente de variação da área, conectividade primária e conectividade estuarina) e variáveis de uso e cobertura da terra (buffer de 50, 100, 250 e 500 m). Dados de ictiofauna foram obtidos através de amostragem padronizada com rede de espera e de arrasto em 38 lagoas. Nossos resultados mostram que diferentes descritores da comunidade respondem a diferentes variáveis de paisagem. Quando considerada a composição de assembleias que habitam diferentes porções do corpo d’água observamos que 18% da variação nas assembleias de margens rasas são explicadas pelas variáveis estruturais e de uso e cobertura; já assembleias que habitam margens mais profundas respondem apenas as variáveis estruturais, as quais explicam 7% da variação nessa assembleia. Ambas as assembleias possuem partição de variância equilibrada entre variáveis que representam o isolamento e a heterogeneidade da paisagem. No entanto, quando consideramos outros descritores da comunidade como diversidade alfa e beta, observamos que as variáveis estruturais e de uso e cobertura da terra são mais importantes para explicar a diversidade dentro do corpo d’água (alfa), não sendo significantes para predizer a diversidade entre corpos d’água (beta). Esses resultados nos sugerem que as assembleias de peixes de lagoas costeiras podem estar estruturadas dentro de uma metacomunidade onde o efeito de massa pode ser o paradigma que melhor explica os padrões observados. / Coastal lagoons are dynamics ecosystems characterized by high levels of biodiversity, and they can be envisaged as discrete patches immersed in the landscape. Community patterns observed in coastal lagoons can be explained by ecological theories, such as, Island Biogeography and Metacommunity Ecology. These theories emphasize that the degree of isolation and habitat heterogeneity, in the landscape scale, are important factors defining community patterns. Our aim was to investigate the influence of these factors on different community descriptors (species composition, alpha and beta diversity) of fish communities in coastal lagoons, using landscape metrics. Our study area is located in the Tramandaí river system, RS (50,14°O; 29,98°S). This system communicates with the ocean through the Tramandaí estuary, and it encompasses 41 lagoons with different degrees of connection. We quantified landscape variables using geographic information systems (Spot and Landsat-TM5 images). These variables were grouped in two categories; structural variables (area, shape, distance to the ocean, coefficient of variation of area, primary connectivity and estuarine connectivity) and land use/land cover variables (using buffers of 50, 100, 250 and 500 m). Ichthyofauna data were obtained through standardized sampling, using gillnets and trawls in 38 lagoons. Our results show that different community descriptors respond to different landscape variables. Altogether, structural and land use/land cover variables explain 18% of the variation of fish composition (abundance) of shallow margins; while structural variables explain 7% of the total variation of fish composition inhabiting deeper banks. Both assemblages exhibit a balanced partition of variation among variables representing landscape isolation and heterogeneity. However, when considering other community descriptors, such as, alpha and beta diversity, we observed that landscape variables are more important in explaining the diversity within each lagoon (alpha), but they are not significant in predicting diversity between lagoons (beta). These results suggest that fish assemblages of coastal lagoons can be structured within a metacommunity, and that the mass effect may be the paradigm that better explains the observed patterns.
22

Hydroelastic Response of Hydrofoil Under Cavitation Conditions / Hydroelastic Response of Hydrofoil Under Cavitation Conditions

Čupr, Pavel January 2021 (has links)
Tato disertační práce se zabývá experimentálním a výpočtovým výzkumem přídavných účinků od proudu kapaliny na obtékaný hydraulický profil. Dynamická odezva profilu byla analyzována pro dva typy buzení: buzení odtržením mezní vrstvy a Kármánových vírů a dále buzení pomocí externího budiče připojeného k lopatce. Experimentální měření dynamické odezvy profilu na oba typy buzení bylo provedeno pro lopatku umístěnou v kavitujícím a nekavitujícím proudění. Získané výsledky byly použity pro verifikaci přídavných účinků stanovených s využitím numerického modelování.
23

The “Shepard” will guide us: a textual analysis of hegemonic reinforcement and resistance in the mass effect video game series

Unknown Date (has links)
Mass Effect is a Science Fiction/Action Role Playing/Third Person Shooter video game series that takes place in the year 2183, in which the player assumes control of Commander Shepard. Players can choose to customize the character based on his/her gender, appearance, sexual orientation, background origin and occupation. The choices that show up in the game are also based on how the player wants their version of Shepard to interact with other characters and allows players some leeway to shape their own narrative. The series also discusses and acknowledges issues of race, gender, subjecthood and sovereignty, politics and sexual orientation within its narrative. This analysis focuses on the text of the series and its implications concerning hegemonic reinforcement and/or resistance in terms of race, gender, sexual orientation, politics, and warfare tactics. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

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