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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.
71

Genetic differentiation in Alewife populations using microsatellite loci

Chilakamarri, Sunita R 31 May 2005 (has links)
"Local genetic adaptation and homing behavior in anadromous fish favors the formation of local populations across their geographic range of distribution. Spawning- and natal-site fidelity repeated over generations restricts gene flow and allows genetic differences to accumulate resulting in reproductive isolation. This leads to progressive genetic differentiation and population structuring among different river populations. Alewife, Alosa pseudoharengus, are anadromous fish which are estimated to have high rates of reproductive fidelity and hence might show population structuring among different breeding streams. Alewife are fish of economic importance since they have both commercial and recreational value. Alewife populations have been declining over the past decades and conservation measures to restore the populations have been implemented. Since maintaining genetic integrity of natural populations is one of the main concerns, identification of population structure can assist in designing appropriate restocking programs. In this study, I used microsatellite markers developed for shad to study population structuring in alewife. Samples were collected from two sites in Connecticut and one in Lake Michigan and genetic differentiation among these populations was estimated using five microsatellite loci. My studies indicate that microsatellite loci developed for shad can be used for alewife. Results from this preliminary study indicated subtle but significant genetic differentiation among populations. This suggests that care should be taken when restocking alewife from different sites in order to maintain genetic diversity among these populations."
72

Caracterização fenológica da vegetação por análise harmônica em séries temporais EVI/MODIS no Parque Nacional das Araucárias

Santos, Tiago Rafael dos January 2017 (has links)
A floresta ombrófila mista, representada principalmente pela presença de Araucaria angustifolia possui elevada importância para a região sul do Brasil e o interesse econômico nessa espécie ocasionou uma forte exploração principalmente durante a primeira metade do século XX. O Parque Nacional das Araucárias possui a finalidade de preservar remanescentes de florestas com a presença de Araucaria angustifolia; sendo assim, a compreensão do comportamento da dinâmica fenológica das coberturas florestais é uma forma de auxiliar na gestão e manejo destas áreas. Dessa forma, foi executado a aplicação de uma metodologia baseada em análises harmônicas de séries temporais EVI/MODIS para realizar a caracterização e mapeamento fenológico das diferentes coberturas vegetais presentes no Parque Nacional das Araucárias, por meio desta metodologia foi possível identificar os valores médios de EVI durante toda a série temporal para as diferentes coberturas de uso e ocupação do solo, analisando a relação entre as variações fenológicas com dados de precipitação e temperatura máxima, representando essas variações de amplitude, fase e termo aditivo para a série completa e individualmente para cada ano. Baseado no algoritmo HANTS, aplicou-se a análise harmônica para uma série temporal de dez anos, compreendidas entre os anos de 2006 a 2015. A partir desse processamento foram analisadas as imagens de fase, amplitude e termo aditivo por meio de quatro conjunto de amostras previamente selecionadas, representando as quatro principais coberturas de vegetação presentes no parque. Com o intuito de auxiliar na interpretação visual dos dados, as imagens foram convertidas de RGB para HLS. Uma vez gerados todos os dados, foi possível caracterizar como ocorre a variação dos valores de índices de vegetação ao longo do ano, bem como o período do ano onde acontecem as maiores variações; além de ser possível indicar as áreas onde houve indicativos de mudanças significativas de uso do solo, mudanças ocasionadas por algum evento climático ou pelo próprio desenvolvimento da vegetação. Através dos dados extraídos com a análise harmônica e a identificação das diferentes fenologias gerou-se também uma classificação sobre a série temporal, com o objetivo de identificar as áreas que ainda apresentam remanescentes de Araucaria angustifolia de forma predominante. Por fim, concluiu-se que a aplicação de uma metodologia baseada em séries harmônicas possibilita uma maior compreensão das coberturas florestais presentes nesta unidade de conservação gerando informações úteis para a gestão e possível revisão do plano de manejo. Para alguma aplicação futura, espera-se utilizar esta metodologia em uma série temporal com maior resolução espacial. / The Mixed Coniferous-Broadleaf forest, mainly represented by the presence of Araucaria angustifolia, is highly important to the southern region of Brazil, the economic interest in this species led to a heavy exploration during the first half of the 20th century. The purpose of the Araucárias National Park is to preserve remnants of the forests with great presence of Araucaria angustifolia; therefore, the comprehension of the behavior of the phenological dynamic of the forest covers is a way of assisting the management and handling of these areas. Thereby, the goal is to apply a methodology based on harmonic analysis of EVI / MODIS time series to perform characterization and phenological mapping of the different vegetation covers present in Araucarias National Park; for that, it is intended to identify the medial values of EVI during the whole time series for different types of coverage of soil use and occupation, analyzing the relation between the phenological variations with precipitation data and maximum temperature, representing these variations of amplitude, phase and additive term for a complete series and individually for each year. Based on the HANTS algorithm, the harmonic analysis was applied to a time series of ten years, comprised between 2006 and 2015. Starting from this processing, images of the phase, amplitude and additive term were analyzed by means of four previously selected samples, representing the four main vegetation covers present in the park. In order to assist the visual interpretation of data, the images were converted from RGB to HLS. When all data was generated, it was possible to characterize how the variation in the value of vegetation indices happen throughout the year, as well as the time of the year when the biggest variations occur. Besides, it is possible to indicate the areas with significant changes in the use of soil, or changes caused by climatic events or by the vegetation own development. Through the data extracted with the harmonic analysis and the identification of the different phenologies, a classification was also generated on the time series, in order to identify the areas that still present remnants of Araucaria angustifolia predominantly.Ultimately, it is concluded that the application of a methodology based on the harmonic series enables a better comprehension of the forest covers present in this unity of conservation, generating useful information for the management and possible review of the management plan. For future application, the use of this methodology in a time series with greater spatial resolution is expected.
73

Proposta de um índice para avaliação de conformidade da qualidade dos corpos hídricos ao enquadramento. / Proposal of an index for assessment of conformity of quality of water bodies to the framework.

Cristiane Araújo Amaro 24 April 2009 (has links)
O Brasil é um dos países mais ricos em água doce, mas também repleto de problemas relacionados à qualidade de suas águas, prejudicando a disponibilidade necessária para os seus múltiplos usos. O quadro de degradação da qualidade dos corpos hídricos brasileiros gerou a necessidade do estabelecimento de medidas que assegurassem a sustentabilidade destes usos e o enquadramento é considerado uma das ferramentas estratégicas para esta garantia, porque por meio desta é possível o estabelecimento de metas de qualidade da água, as quais devem ser alcançadas ou mantidas no corpo hídrico ao longo do tempo. A Política Nacional de Recursos Hídricos (Lei n. 9.433/1997) define o enquadramento como um de seus instrumentos para a gestão integrada da qualidade e quantidade da água e a Resolução CONAMA n.357/2005 classifica os corpos hídricos brasileiros segundo os seus usos preponderantes e define padrões de qualidade que devem ser obedecidos para a garantia da sustentabilidade hídrica. O acompanhamento da situação de enquadramento precisa ser encarado como uma atividade essencial para o planejamento de uma bacia hidrográfica e para auxiliar os gestores de recursos hídricos nos processos decisórios. Este trabalho apresenta o estudo de um índice capaz de informar de forma clara e objetiva a situação do corpo hídrico em relação à meta de qualidade da água proposta. O índice está baseado no IQA desenvolvido pelo Canadian Council of Ministers of the Environmental no Canadá, é um método fundamentado na excedência de padrões de qualidade da água previamente definidos, apropriado para o caso brasileiro, pois permite além da avaliação, a inclusão de novas variáveis e padrões de qualidade da água para os diversos usos hídricos. Os resultados obtidos são capazes de mostrar o comportamento dos rios estudados ao longo do tempo em relação a sua condição hídrica, permitindo a localização dos pontos da bacia que precisam de medidas para atender aos padrões estabelecidos pela Resolução CONAMA n.357. / Brazil is one of the richest countries in freshwater, but also full of problems related to the quality of the water, impairing the availability required for its multiple uses. The picture of degradation of the quality of water bodies has led Brazil to the need of establishing measures to ensure the sustainability of these uses and the framing is considered one of the strategic tools for this guarantee, with the establishment of water quality objectives, which must be achieved or kept in the water body over time. The National Water Resources Policy (Law n. 9.433/1997) establishes the framing as one of its instruments for integrated management of water quality and quantity and Resolution CONAMA n.357/2005 classifies the Brazilian water bodies according to their predominant uses and defines quality standards that must be obeyed to guarantee sustainability of the water. Monitoring the situation of environment must be seen as an essential activity to the planning of a watershed and to facilitate the decision-making process in the water resources management. This paper presents the initial study of an index able to report clearly and objectively the situation of the water body in relation to the goal of water quality proposal. The index is based on the Water Quality Index (WQI) developed by the Canadian Council of Ministers of the Environmental Canada, is a method based on exceedance of water quality standards previously defined, appropriate for the Brazilian case, it allows also the evaluation, the inclusion of new variables and water quality objectives for various water uses. The results are able to show the behavior of the rivers studied over time in relation to their water condition and identifies critical areas of the watershed in need of additional pollution control practices to achieve the desired water quality standards by CONAMA n.357 Resolution.
74

Assessing sewage disposals in soft-bottom habitats / Evaluación del vertido de aguas residuales urbanas sobre hábitats de fondos blandos

de-la-Ossa-Carretero, Jose Antonio 02 December 2011 (has links)
No description available.
75

Essays on Capability Indices for Autocorrelated Data

Wallgren, Erik January 2007 (has links)
<p>The use of process capability indices in the industry is traditionally based on the assumptions that a sample from a process are observations on independently, identically and normally distributed random variables<i>, IIN</i>. However, all three assumptions are open to discussion and in this thesis, the estimation of the indices is studied when the assumption of independence is not fulfilled.</p><p>In five reports, the indices <i>C</i><i>pk</i> and <i>C</i><i>pm </i>are studied, and instead of random samples, samples are regarded as observations on a time series.</p><p>In the first four reports, each index is studied for either an <i>AR(1)</i> or an <i>MA(1)</i> process and the fifth report, both indices are studied for a general <i>ARMA(p,q</i>) process.</p><p>In all reports, alternatives to <i>C</i><i>pk</i><i> </i>and <i>C</i><i>pm</i><i> </i>are suggested as well as point and interval estimators for the suggested indices. The accuracy of interval estimators are evaluated through large Monte Carlo simulations and the difference between empirical coverage rates and nominal confidence limits are calculated.</p><p>It was found in all reports that a dependency among observations has a great impact on the coverage rates. The coverage rate difference depends on both the size of the autocorrelation and the type of time series model and for the original <i>C</i><i>pk</i> and <i>C</i><i>pm</i> the difference can be large. With the suggested alternative indices, however, the differences are always reduced and unless the autocorrelations are close to ±1, the sizes of differences are of little consequence.</p>
76

Essays on Capability Indices for Autocorrelated Data

Wallgren, Erik January 2007 (has links)
The use of process capability indices in the industry is traditionally based on the assumptions that a sample from a process are observations on independently, identically and normally distributed random variables, IIN. However, all three assumptions are open to discussion and in this thesis, the estimation of the indices is studied when the assumption of independence is not fulfilled. In five reports, the indices Cpk and Cpm are studied, and instead of random samples, samples are regarded as observations on a time series. In the first four reports, each index is studied for either an AR(1) or an MA(1) process and the fifth report, both indices are studied for a general ARMA(p,q) process. In all reports, alternatives to Cpk and Cpm are suggested as well as point and interval estimators for the suggested indices. The accuracy of interval estimators are evaluated through large Monte Carlo simulations and the difference between empirical coverage rates and nominal confidence limits are calculated. It was found in all reports that a dependency among observations has a great impact on the coverage rates. The coverage rate difference depends on both the size of the autocorrelation and the type of time series model and for the original Cpk and Cpm the difference can be large. With the suggested alternative indices, however, the differences are always reduced and unless the autocorrelations are close to ±1, the sizes of differences are of little consequence.
77

The Timeliness of Accounting Write-downs by U.S. Financial Institutions during the Financial Crisis of 2007-2008

Vyas, Dushyantkumar Maheshkumar 17 February 2011 (has links)
This study examines the timeliness of write-downs taken by U.S. financial institutions during the financial crisis of 2007-2008. The timeliness of write-downs is measured by benchmarking the quarterly accounting write-down schedule with the devaluation schedule implied by credit indices such as the ABX. The results show that accounting write-downs are less timely than the devaluations implied by credit indices. In a cross-sectional analysis of the determinants of the timeliness of write-downs, I document that higher corporate governance quality is positively related to timelier write-downs. Furthermore, I observe that regulatory investigations and litigation pressure are positively related to the timeliness of write-downs, whereas the write-downs by firms with more complex exposures, higher financial leverage, and tighter regulatory constraints are less timely. In addition, I control for numerous exposure-specific characteristics and document that less risky exposures, and exposures that were affected later during the financial crisis, were written down later. Regarding the consequences of timeliness, this study finds that the exposure to risky assets is reflected faster in stock returns for firms with timelier write-downs.
78

The Timeliness of Accounting Write-downs by U.S. Financial Institutions during the Financial Crisis of 2007-2008

Vyas, Dushyantkumar Maheshkumar 17 February 2011 (has links)
This study examines the timeliness of write-downs taken by U.S. financial institutions during the financial crisis of 2007-2008. The timeliness of write-downs is measured by benchmarking the quarterly accounting write-down schedule with the devaluation schedule implied by credit indices such as the ABX. The results show that accounting write-downs are less timely than the devaluations implied by credit indices. In a cross-sectional analysis of the determinants of the timeliness of write-downs, I document that higher corporate governance quality is positively related to timelier write-downs. Furthermore, I observe that regulatory investigations and litigation pressure are positively related to the timeliness of write-downs, whereas the write-downs by firms with more complex exposures, higher financial leverage, and tighter regulatory constraints are less timely. In addition, I control for numerous exposure-specific characteristics and document that less risky exposures, and exposures that were affected later during the financial crisis, were written down later. Regarding the consequences of timeliness, this study finds that the exposure to risky assets is reflected faster in stock returns for firms with timelier write-downs.
79

Comparative analysis of emerging markets hedge funds and emerging markets benchmark indices performance

Kotorova, Irina, Sandström, Mattias January 2011 (has links)
Many hedge funds are believed to yield considerable returns to investors; there is an assumption that suggests hedge funds seem uncorrelated with market fluctuations and have relatively low volatility. In recent years, emerging market hedge funds have experienced a higher capital inflow in periods when the diversification benefits of investing in emerging markets are higher. However, the strategy‟s share of the hedge fund industry‟s total capital flows has decreased significantly during the same periods: this might imply that investors have reallocated capital to other hedge fund strategies. This paper investigates whether emerging markets hedge funds have been as consistent in performance as the benchmark indices by presenting results of comparative analysis of two sample emerging markets hedge fund indices and two standard emerging markets benchmarks performance. The empirical study ranges from the period of January 2006 to December 2010.
80

Froecast the USA Stock Indices with GARCH-type Models

Cai, Xinhua January 2012 (has links)
No description available.

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