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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.
11

Modelo sigma não linear acoplado à supergravidade em 1+1 dimensões / Nonlinear sigma model in 1+1 dimensions coupled to supergravity

Jasinschi, Radu Serban 24 March 1983 (has links)
O modelo não linear supersimétrico em l+l dimensões é acoplado à supergravidade. Ao quantizarmos a teoria, os campos de matéria adquirem massa dinamicamente, o que ocasiona a quebra da invariança de Weyl. Este fato implica em que as funções de dois pontos do Gravitino e do Graviton, obtidas a partir da ação efetiva, não sejam triviais. Em particular a função de dois pontos do Gravitino apresenta um polo no infravermelho. Nós conjeturamos que este polo está ligado com o confinamento dos graus de liberdade supersimétricos da teoria. Isto porque, ao restringirmos o domínio de integração de x IND. 1 à uma medida finita L (quebrando as invarianças da teoria), aparece na função de dois pontos do Gravitino um termo de massa, que decresce exponencialmente em função de L. Neste contexto relacionamos este model o como da corda supersimetrica e definimos um critério de estabilidade para a mesma. / The nonlinear o supersymmetric model in l+l dimensions is coupled to supergravity. When we quantize the theory, the matter fields acquire mass dynamically, which leads to the breaking of the Weyl invariance. This fact implies that the two point functions of the Gravitino and the Graviton, obtained from the effective action, become non trivial. Particularly, the two point function of the Gravitino presents a pole in the infrared region. We conjecture that this pole is related to the confinement of all supersymmetric degrees of freedom of the theory. If we restraind the integration domain of x1 to a finite lengh L (breaking all invariances of the theory), there appears a mass term in two point function of the Gravitino, which decreases exponentially with L. In this context we relate this model with that of the supersymmetric string and define a stability criteria for the latter.
12

Representação de comercialização agropecuária através de modelo de Data Warehouse. / Livestock and agriculture market representation through Data Warehouse model.

Fernando Elias Correa 17 December 2009 (has links)
A comercialização de produtos agropecuários tem grande importância para o Brasil, sendo responsável por altos índices de produção e financeiro. E como para todo grande segmento, o acesso à informação tem se tornado essencial para manter a competitividade no ambiente globalizado. Apesar de o agronegócio possuir um grande volume de informações, as mesmas muitas vezes estão inconsistentes ou inacessíveis. Nesse contexto, ainda se observam a necessidade de ampliação de pesquisas que busquem minimizar essa falta de dados que podem auxiliar produtores, agentes de mercado e principalmente pesquisadores para que desenvolvam análises para o mercado agropecuário para servir de apoio para as tomadas de decisões sobre a comercialização diária desses produtos. A técnica usada por diversos segmentos que visam a melhorar e a permitir acesso a dados para tomada de decisão é conhecida como Data Warehouse, pois provê um ambiente propício para análises e acesso a informações consolidadas e históricas. O objetivo do estudo foi demonstrar o processo de análise efetuado por pesquisadores para obtenção de dados, e aplicar dois estudos de casos usando técnicas de Data Warehouse, sendo para dados de comercialização de pecuária e para dados de grãos (soja e milho), gerando assim o modelo dimensional, a matriz de barramento e aplicação da ferramenta de processamento analítico online. O resultado do estudo de pecuária permitiu gerar os modelos iniciais para a cadeia, e podem ser expandidos com a inclusão de novos produtos, bem como auxiliar o pesquisador na geração de análises com a utilização das ferramentas para acesso ao Data Mart. Assim como foi possível gerar análises de comercialização de grãos a partir de dados armazenados no Data Mart. Portanto, pode-se afirmar que a aplicação e expansão da técnica de Data Warehouse é viável para outras cadeias do agronegócio possibilitando a ampliação e a melhoria da oferta de informações. / The agricultural and livestock markets in Brazil play important roles both for the production and the financial sectors. However, like other business, information is essential to maintain the competitiveness in the global market. Although the agribusiness sector processes high amount of information on a daily basis, it is almost always inconsistent or inaccessible. Moreover, there is little research aimed at minimizing the lack of agribusiness information available for the producers, market agents and researchers in order to develop data analyses on agribusiness, to help in the decision process. The technique commonly used in other segments, such as industries, is called Data Warehouse, which provides an environment to provide access to data and consistent information. The goals of this research were to present what researchers what they can do to perform agribusiness analysis, how to apply Data Warehouse modeling and the application of the tool to this process. To reach these goals, we evaluated two case studies. The first study used data from the livestock market, as it allowed to generate initial data for the chain and because it can be applied to other products, as well as to help the researcher to analyze using the OLAP tool. At the same line, the study about grain market was developed, and models and OLAP tools were developed to help with the particular points for this chain. Concluding, the research shows that it is viable to use Data Warehouse techniques to create an agribusiness data environment, consistent and organized, which can be expanded to new agricultural products.
13

In vitro simulation of calcific aortic valve disease in three-dimensional bioprinted models

Wu, Pin-Jou 14 July 2017 (has links)
BACKGROUND: Calcific aortic valve disease (CAVD) is the most prevalent heart valve disease in the developed world, claiming almost 17,000 deaths annually in the United States. The lack of noninvasive therapeutics to slow or halt the disease warrants the need for further understanding of the pathobiological mechanisms of CAVD. A tri-laminar structure of aortic valve determines the biomechanical properties of its leaflets. Valvular endothelial cells (VECs) and interstitial cells (VICs) are responsible for valve structural integrity. Traditional two-dimensional culture conditions spontaneously activate the pathological differentiation of VICs making in vitro studies challenging. A monolayered three-dimensional (3D) hydrogel platform was recently developed as a novel in vitro culture system to study the phenotypic changes of VICs leading to microcalcification (early stages of calcification). This system, however, did not fully recapitulate the microenvironment of native valve tissues because of the lack of individual layer representations and endothelial coverage. Bioprinting technology, which allows precise and integrated positioning of cells, matrix, and biomolecules, may provide an innovative approach toward building a more biologically relevant 3D culture platform. OBJECTIVE: This study aims to lay the groundwork for building a multilayered 3D-bioprinted culture platform to study CAVD by first validating the use of bioprinting in monolayered cell-laden 3D hydrogel constructs. METHODS: Human VICs were isolated from patients undergoing valve replacement surgeries at Brigham and Women’s Hospital (Boston, MA) according to Institutional Review Board (IRB) protocols. VICs were expanded in culture medium containing growth factors for up to 6 passages and then encapsulated in hydrogels using 3D bioprinting technology. After encapsulation, VIC-laden 3D constructs were cultured in either normal or osteogenic conditions for 21 days. Microcalcification, cell proliferation, and cell apoptosis were evaluated using fluorescent staining and confocal microscopy. Results were compared with results from VIC-laden hydrogels made manually. RESULTS: An increase in microcalcification was observed throughout bioprinted VIC-laden hydrogel constructs cultured in osteogenic conditions for 21 days, whereas normal conditions developed negligible calcification signals. Cell proliferation and apoptosis were not significantly different between normal and osteogenic groups in bioprinted hydrogels. Cell-free hydrogels did not exhibit any microcalcification. Overall, bioprinted hydrogels showed less nonspecific background staining than handmade hydrogels, thus providing a better means for quantitative assessments of 3D culture platforms. CONCLUSION: Based on bioprinting technology, an improved monolayered cell-laden hydrogel platform was successfully established as a first step toward building an in vitro multilayered disease model for studying the pathobiological mechanisms of CAVD. The results in this study were consistent with current literature that proposes calcification as a cell-dependent, apoptotic-independent, and proliferation-independent pathway. / 2019-07-13T00:00:00Z
14

Initial Examination of the English-language Dimensional Personality Symptom Item Pool

Ivanova, Anna 12 February 2010 (has links)
Dimensional models of personality pathology present a promising approach to the assessment of maladaptive personality in adults and children (eg. De Clercq, De Fruyt, & Widiger, 2009). In addition, recent findings show that some childhood maladaptive traits can be predictive of adulthood personality disorders (eg. Mervielde, De Clercq, De Fruyt, & Van Leeuwen, 2005). The Dimensional Personality Symptom Item Pool (DIPSI) is a questionnaire designed to measure maladaptive lower and higher order traits in children and adolescents. This study aims to examine the DIPSI’s scales and to replicate several previous findings of maladaptive trait patterns in children. The results indicate that the DIPSI’s lower and higher order trait scales are high in reliability and show many of the trait relationships suggested by previous literature. A successful outcome of this study serves as the first step towards establishing the DIPSI as a valid and useful measure of personality pathology in children.
15

Initial Examination of the English-language Dimensional Personality Symptom Item Pool

Ivanova, Anna 12 February 2010 (has links)
Dimensional models of personality pathology present a promising approach to the assessment of maladaptive personality in adults and children (eg. De Clercq, De Fruyt, & Widiger, 2009). In addition, recent findings show that some childhood maladaptive traits can be predictive of adulthood personality disorders (eg. Mervielde, De Clercq, De Fruyt, & Van Leeuwen, 2005). The Dimensional Personality Symptom Item Pool (DIPSI) is a questionnaire designed to measure maladaptive lower and higher order traits in children and adolescents. This study aims to examine the DIPSI’s scales and to replicate several previous findings of maladaptive trait patterns in children. The results indicate that the DIPSI’s lower and higher order trait scales are high in reliability and show many of the trait relationships suggested by previous literature. A successful outcome of this study serves as the first step towards establishing the DIPSI as a valid and useful measure of personality pathology in children.
16

Efficient Computational Methods for Structural Reliability and Global Sensitivity Analyses

Zhang, Xufang 25 April 2013 (has links)
Uncertainty analysis of a system response is an important part of engineering probabilistic analysis. Uncertainty analysis includes: (a) to evaluate moments of the response; (b) to evaluate reliability analysis of the system; (c) to assess the complete probability distribution of the response; (d) to conduct the parametric sensitivity analysis of the output. The actual model of system response is usually a high-dimensional function of input variables. Although Monte Carlo simulation is a quite general approach for this purpose, it may require an inordinate amount of resources to achieve an acceptable level of accuracy. Development of a computationally efficient method, hence, is of great importance. First of all, the study proposed a moment method for uncertainty quantification of structural systems. However, a key departure is the use of fractional moment of response function, as opposed to integer moment used so far in literature. The advantage of using fractional moment over integer moment was illustrated from the relation of one fractional moment with a couple of integer moments. With a small number of samples to compute the fractional moments, a system output distribution was estimated with the principle of maximum entropy (MaxEnt) in conjunction with the constraints specified in terms of fractional moments. Compared to the classical MaxEnt, a novel feature of the proposed method is that fractional exponent of the MaxEnt distribution is determined through the entropy maximization process, instead of assigned by an analyst in prior. To further minimize the computational cost of the simulation-based entropy method, a multiplicative dimensional reduction method (M-DRM) was proposed to compute the fractional (integer) moments of a generic function with multiple input variables. The M-DRM can accurately approximate a high-dimensional function as the product of a series low-dimensional functions. Together with the principle of maximum entropy, a novel computational approach was proposed to assess the complete probability distribution of a system output. Accuracy and efficiency of the proposed method for structural reliability analysis were verified by crude Monte Carlo simulation of several examples. Application of M-DRM was further extended to the variance-based global sensitivity analysis of a system. Compared to the local sensitivity analysis, the variance-based sensitivity index can provide significance information about an input random variable. Since each component variance is defined as a conditional expectation with respect to the system model function, the separable nature of the M-DRM approximation can simplify the high-dimension integrations in sensitivity analysis. Several examples were presented to illustrate the numerical accuracy and efficiency of the proposed method in comparison to the Monte Carlo simulation method. The last contribution of the proposed study is the development of a computationally efficient method for polynomial chaos expansion (PCE) of a system's response. This PCE model can be later used uncertainty analysis. However, evaluation of coefficients of a PCE meta-model is computational demanding task due to the involved high-dimensional integrations. With the proposed M-DRM, the involved computational cost can be remarkably reduced compared to the classical methods in literature (simulation method or tensor Gauss quadrature method). Accuracy and efficiency of the proposed method for polynomial chaos expansion were verified by considering several practical examples.
17

Three-dimensional shear wave velocity structure in the Atlantic upper mantle

James, Esther Kezia 21 June 2016 (has links)
Oceanic lithosphere constitutes the upper boundary layer of the Earth’s convecting mantle. Its structure and evolution provide a vital window on the dynamics of the mantle and important clues to how the motions of Earth’s surface plates are coupled to convection in the mantle below. The three-dimensional shear-velocity structure of the upper mantle beneath the Atlantic Ocean is investigated to gain insight into processes that drive formation of oceanic lithosphere. Travel times are measured for approximately 10,000 fundamental-mode Rayleigh waves, in the period range 30-130 seconds, traversing the Atlantic basin. Paths with >30% of their length through continental upper mantle are excluded to maximize sensitivity to the oceanic upper mantle. The lateral distribution of Rayleigh wave phase velocity in the Atlantic upper mantle is explored with two approaches. One, phase velocity is allowed to vary only as a function of seafloor age. Two, a general two-dimensional parameterization is utilized in order to capture perturbations to age-dependent structure. Phase velocity shows a strong dependence on seafloor age, and removing age-dependent velocity from the 2-D maps highlights areas of anomalously low velocity, almost all of which are proximal to locations of hotspot volcanism. Depth-dependent variations in vertically-polarized shear velocity (Vsv) are determined with two sets of 3-D models: a layered model that requires constant VSV in each depth layer, and a splined model that allows VSV to vary continuously with depth. At shallow depths (~75 km) the seismic structure shows the expected dependence on seafloor age. At greater depths (~200 km) high-velocity lithosphere is found only beneath the oldest seafloor; velocity variations beneath younger seafloor may result from temperature or compositional variations within the asthenosphere. The age-dependent phase velocities are used to constrain temperature in the mantle and show that, in contrast to previous results for the Pacific, phase velocities for the Atlantic are not consistent with a half-space cooling model but are best explained by a plate-cooling model with thickness of 75 km and mantle temperature of 1400oC. Comparison with data such as basalt chemistry and seafloor elevation helps to separate thermal and compositional effects on shear velocity.
18

Modelo sigma não linear acoplado à supergravidade em 1+1 dimensões / Nonlinear sigma model in 1+1 dimensions coupled to supergravity

Radu Serban Jasinschi 24 March 1983 (has links)
O modelo não linear supersimétrico em l+l dimensões é acoplado à supergravidade. Ao quantizarmos a teoria, os campos de matéria adquirem massa dinamicamente, o que ocasiona a quebra da invariança de Weyl. Este fato implica em que as funções de dois pontos do Gravitino e do Graviton, obtidas a partir da ação efetiva, não sejam triviais. Em particular a função de dois pontos do Gravitino apresenta um polo no infravermelho. Nós conjeturamos que este polo está ligado com o confinamento dos graus de liberdade supersimétricos da teoria. Isto porque, ao restringirmos o domínio de integração de x IND. 1 à uma medida finita L (quebrando as invarianças da teoria), aparece na função de dois pontos do Gravitino um termo de massa, que decresce exponencialmente em função de L. Neste contexto relacionamos este model o como da corda supersimetrica e definimos um critério de estabilidade para a mesma. / The nonlinear o supersymmetric model in l+l dimensions is coupled to supergravity. When we quantize the theory, the matter fields acquire mass dynamically, which leads to the breaking of the Weyl invariance. This fact implies that the two point functions of the Gravitino and the Graviton, obtained from the effective action, become non trivial. Particularly, the two point function of the Gravitino presents a pole in the infrared region. We conjecture that this pole is related to the confinement of all supersymmetric degrees of freedom of the theory. If we restraind the integration domain of x1 to a finite lengh L (breaking all invariances of the theory), there appears a mass term in two point function of the Gravitino, which decreases exponentially with L. In this context we relate this model with that of the supersymmetric string and define a stability criteria for the latter.
19

Extending dimensional modeling through the abstraction of data relationships and development of the semantic data warehouse

Hart, Robert 04 December 2017 (has links)
The Kimball methodology, often referred to as dimensional modelling, is well established in data warehousing and business intelligence as a highly successful means for turning data into information. Yet weaknesses exist in the Kimball approach that make it difficult to rapidly extend or interrelate dimensional models in complex business areas such as Health Care. This Thesis looks at the development of a methodology that will provide for the rapid extension and interrelation of Kimball dimensional models. This is achieved through the use of techniques similar to those employed in the semantic web. These techniques allow for rapid analysis and insight into highly variable data which previously was difficult to achieve. / Graduate
20

Koncepce reportingu v nákladovém controllingu / The concept of reporting in cost controlling

Vojtek, Michal January 2012 (has links)
This diploma thesis describes a proposal of a new conception of cost controlling reporting in Česká spořitelna for next period. This reporting concept consists of a description of the dimensional model (including a detailed description of dimensions and metrics reporting), the application architecture design and benefits of the new solution. The theoretic part focuses on specification of the basic reporting terms that are further developed in a practical part. Specifically, this section describes and categorizes reporting, including identification of the main groups of users (consumers) reports, identifies the main reporting components - requirements, tools and architecture. The practical part consists of three chapters supporting the achievement of the main targets. The first chapter defines the role of cost controlling, describes the current reporting conception through the model of application architecture. At the end, it summarizes the main limitations and shortcomings of the current reporting concept. The second chapter is fully devoted to the Erste reporting, and evaluates new demands and reporting requirements. The part of chapter is a catalogue of reports and reporting road map. It serves as a dashboard that can warn against potential operational risks. The last chapter meets the main goal and introduces a solution of reporting concept of cost controlling. The benefits of work can be especially found in practical application in Česká spořitelna. Currently, the first implementation phase of the Hyperion planning application has been realized. Moreover subject of my thesis can serve as a valuable source of information describing both current and final status of cost reporting.

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