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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.
81

Avaliação dos níveis de concentração e identificação de fontes de hidrocarbonetos na Bacia do Alto Iguaçu: estudo de caso pós derrame acidental de óleo na refinaria Presidente Getúlio Vargas

Gallota, Fabiana Dias Costa 02 May 2016 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-05-02T17:58:54Z No. of bitstreams: 1 GALLOTTA_30_06_14.pdf: 62695484 bytes, checksum: 33335ee3affc2bcffb11fc10caf9ae3f (MD5) / Made available in DSpace on 2016-05-02T17:58:54Z (GMT). No. of bitstreams: 1 GALLOTTA_30_06_14.pdf: 62695484 bytes, checksum: 33335ee3affc2bcffb11fc10caf9ae3f (MD5) / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / Os hidrocarbonetos presentes no ambiente consistem em misturas complexas de compostos derivados de múltiplas fontes. Os combustíveis fósseis representam a principal contribuição, devido à taxa e escala espacial, em que o petróleo tem sido usado como fonte de energia e matéria-prima para a indústria química. O objetivo deste estudo foi avaliar os níveis de concentração e identificar fontes de hidrocarbonetos na Bacia do Alto Iguaçu e, em especial, na área de influência da Refinaria Presidente Getúlio Vargas (REPAR). Além dos fatores de poluição crônica, a área de estudo foi alvo de um derrame acidental de petróleo em julho de 2000. Diversos indicadores em diferentes compartimentos ambientais (água superficial, sedimento, solo e água subterrânea) foram avaliados na fase pós-derrame e no monitoramento ambiental ao longo de várias campanhas por mais de uma década. Os esforços de avaliação foram concentrados nos seguintes indicadores: os nalcanos, os alcanos isoprenoides, os hidrocarbonetos policíclicos aromáticos (HPA), os biomarcadores de petróleo e ainda o total de hidrocarbonetos de petróleo (THP). Os resultados identificaram como principal aporte de matéria orgânica para as águas superficiais dos rios Barigüi e Iguaçu, os fluxos materiais originados em região a montante do acidente, refletindo a contribuição antropogênica crônica da cidade de Curitiba. Em 2007 e 2008, as concentrações de THP e HPA nas águas superficiais e sedimentos dos rios Barigüi e Iguaçu refletem uma expressiva melhoria nas condições desses rios em relação a 2000. Na área interna da refinaria (Ponto Zero), observou-se uma nítida diminuição (atenuação) natural das concentrações de THP no solo em todas as profundidades dos perfis amostrados ao longo do tempo nos Banhados 1 e 4 e, em particular, uma diminuição importante das concentrações entre 2004 e 2007. Para a identificação das fontes de hidrocarbonetos foram utilizadas razões diagnósticas e quimiometria. As razões diagnósticas calculadas a partir de concentrações de HPA sugeriram que, na maioria dos sedimentos dos Rios Barigüi e Iguaçu coletados nas campanhas de 2000 e 2001, a fonte petrogênica é a principal. Somente na estação a montante do acidente no Rio Barigüi, a fonte pirolítica predominou nestas duas campanhas. As razões diagnósticas que apresentaram maior eficiência na identificação de fontes de hidrocarbonetos nos sedimentos dos rios Barigüi e Iguaçu foram: ΣC1-Fenantrenos/Fenantreno; e (ΣHPA parentais de 3-6 anéis)/(Σ5 séries de HPA alquilados). A identificação de fontes através de razões diagnósticas calculadas a partir de áreas e alturas de picos cromatográficos demonstrou sua aplicabilidade verificando a relação entre os compostos encontrados em amostras de solo da área interna da refinaria com a amostra de petróleo derramado no acidente, após quase uma década da ocorrência do vazamento. A identificação de fontes através método de quimiométrico baseado na análise de componentes principais (ACP) de seções pré-processadas e combinadas dos Cromatogramas de Íons Selecionados (CIS) mostrou que as amostras mais contaminadas estão na área interna da refinaria. Essas amostras apresentam um padrão de distribuição petrogênica e diferentes graus de intemperismo. As amostras da área externa à refinaria (Guajuvira, General Lúcio e Balsa Nova) são menos ou não contaminadas e/ou contém uma mistura de contribuições diagenéticas, pirolíticas e petrogênicas onde predominam diferentes proporções. Os locais mais distantes da atividade industrial (Balsa Nova) contem, como esperado, os níveis mais baixos de contaminação por HPA. Os resultados de biomarcadores demonstraram que não há evidências para concluir que as amostras da área externa à refinaria e o óleo Cusiana vazado tenham a mesma origem. Os resultados ao longo dos rios Barigüi e Iguaçu e do Ponto Zero demonstraram que as ações de emergência para a contenção do óleo foram adequadas para os rios, e que a contaminação decorrente do derrame ficou predominantemente contida no Ponto Zero e diminuiu significativamente após uma década. / Hydrocarbons present in the environment consist of complex mixtures of compounds derived from multiple sources. The main contribution lies on fossil fuel inputs due to the rate and spatial scale by which petroleum has been used as an energy source and chemical feedstock. The aim of this study was to assess the concentration levels and identify sources of hydrocarbons in the Upper Iguaçu Watershed and, in particular, in the area of influence of the President Getulio Vargas Refinery (REPAR). In addition to the factors of chronic pollution, the study area was the scenario of an acute accidental oil spill in July 2000. Numerous indicators in different environmental compartments (surface water, sediment, soil and groundwater) were assessed in the post spill phase and during the environmental monitoring programs over the course of several campaigns for more than a decade. Assessment efforts were concentrated on the following indicators: n-alkanes, alkanes isoprenoids, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and total petroleum hydrocarbons (TPH). The results identified as the main contribution of organic matter to surface waters of the Barigüi and Iguaçu Rivers the materials flows originated in the region upstream of the accident, reflecting chronic anthropogenic contribution of the city of Curitiba. In 2007 and 2008, the TPH and PAH concentrations in surface waters and sediments of the Barigüi and Iguaçu Rivers revealed a significant improvement in the conditions of these rivers when compared with 2000. Inside the refinery area (Point Zero), it was observed a clear natural decrease (attenuation) of the concentrations of TPH in the soil at all depths sampled over time in Marshes 1 and 4 and, in particular, an important decrease of concentrations between 2004 and 2007. Diagnostic ratios and chemometrics were used to identity hydrocarbon sources. The diagnostic ratios calculated from the concentrations of PAH suggested that, in the majority of sediments from the Barigüi and Iguaçu Rivers collected in 2000 and 2001 campaigns, the main source is petrogenic. Only in the station upstream the accident in the Barigüi River, the pyrolytic source predominated in these two campaigns. The diagnostic ratios that presented higher efficiency in identifying sources of hydrocarbons in sediments of the Barigüi and Iguaçu Rivers were: ΣC1- Phenantrenes/Phenanthrene; and (Σ3-6 rings parental PAH)/(Σ5 alkylated PAH series). The source identification through diagnostic ratios calculated from heights and areas of chromatographic peaks demonstrated its applicability establishing a relationship between the compounds found in soil samples of the internal area of the refinery and the sample of the oil spilled in the accident, after nearly a decade of occurrence of the spillage. The source identification through chemometric method based on principal components analysis (PCA) of preprocessed and combined sections of Selected Ion Chromatograms (SIC) showed that the most contaminated samples are inside the refinery area. These samples present a petrogenic pattern and different weathering degrees. Samples from outside the refinery area (Guajuvira, General Lúcio e Balsa Nova) are either less or not contaminated, and/or contain mixtures of diagenetic, pyrogenic and petrogenic inputs where different proportions predominate. The locations farthest away from industrial activity (Balsa Nova) contain, as expected, the lowest levels of PAH contamination. The biomarkers results do not show any evidences to conclude positive matches between the samples from outside the refinery area and the spilled Cusiana oil. The results along Barigüi and Iguaçu rivers and Point Zero demonstrated that emergency actions to contain the oil were appropriate for the rivers, and that the contamination resulting from the spill was mostly contained in the Point Zero and decreased significantly after one decade
82

A Multilinear (Tensor) Algebraic Framework for Computer Graphics, Computer Vision and Machine Learning

Vasilescu, M. Alex O. 09 June 2014 (has links)
This thesis introduces a multilinear algebraic framework for computer graphics, computer vision, and machine learning, particularly for the fundamental purposes of image synthesis, analysis, and recognition. Natural images result from the multifactor interaction between the imaging process, the scene illumination, and the scene geometry. We assert that a principled mathematical approach to disentangling and explicitly representing these causal factors, which are essential to image formation, is through numerical multilinear algebra, the algebra of higher-order tensors. Our new image modeling framework is based on(i) a multilinear generalization of principal components analysis (PCA), (ii) a novel multilinear generalization of independent components analysis (ICA), and (iii) a multilinear projection for use in recognition that maps images to the multiple causal factor spaces associated with their formation. Multilinear PCA employs a tensor extension of the conventional matrix singular value decomposition (SVD), known as the M-mode SVD, while our multilinear ICA method involves an analogous M-mode ICA algorithm. As applications of our tensor framework, we tackle important problems in computer graphics, computer vision, and pattern recognition; in particular, (i) image-based rendering, specifically introducing the multilinear synthesis of images of textured surfaces under varying view and illumination conditions, a new technique that we call ``TensorTextures'', as well as (ii) the multilinear analysis and recognition of facial images under variable face shape, view, and illumination conditions, a new technique that we call ``TensorFaces''. In developing these applications, we introduce a multilinear image-based rendering algorithm and a multilinear appearance-based recognition algorithm. As a final, non-image-based application of our framework, we consider the analysis, synthesis and recognition of human motion data using multilinear methods, introducing a new technique that we call ``Human Motion Signatures''.
83

A Multilinear (Tensor) Algebraic Framework for Computer Graphics, Computer Vision and Machine Learning

Vasilescu, M. Alex O. 09 June 2014 (has links)
This thesis introduces a multilinear algebraic framework for computer graphics, computer vision, and machine learning, particularly for the fundamental purposes of image synthesis, analysis, and recognition. Natural images result from the multifactor interaction between the imaging process, the scene illumination, and the scene geometry. We assert that a principled mathematical approach to disentangling and explicitly representing these causal factors, which are essential to image formation, is through numerical multilinear algebra, the algebra of higher-order tensors. Our new image modeling framework is based on(i) a multilinear generalization of principal components analysis (PCA), (ii) a novel multilinear generalization of independent components analysis (ICA), and (iii) a multilinear projection for use in recognition that maps images to the multiple causal factor spaces associated with their formation. Multilinear PCA employs a tensor extension of the conventional matrix singular value decomposition (SVD), known as the M-mode SVD, while our multilinear ICA method involves an analogous M-mode ICA algorithm. As applications of our tensor framework, we tackle important problems in computer graphics, computer vision, and pattern recognition; in particular, (i) image-based rendering, specifically introducing the multilinear synthesis of images of textured surfaces under varying view and illumination conditions, a new technique that we call ``TensorTextures'', as well as (ii) the multilinear analysis and recognition of facial images under variable face shape, view, and illumination conditions, a new technique that we call ``TensorFaces''. In developing these applications, we introduce a multilinear image-based rendering algorithm and a multilinear appearance-based recognition algorithm. As a final, non-image-based application of our framework, we consider the analysis, synthesis and recognition of human motion data using multilinear methods, introducing a new technique that we call ``Human Motion Signatures''.
84

Phytochemical investigation of Acronychia species using NMR and LC-MS based dereplication and metabolomics approaches / Etude phytochimique d’espèces du genre Acronychia en utilisant des approches de déréplication et métabolomique basées sur des techniques RMN et SM

Kouloura, Eirini 28 November 2014 (has links)
Les plantes médicinales constituent une source inexhaustible de composés (des produits naturels - PN) utilisé en médecine pour la prévention et le traitement de diverses maladies. L'introduction de nouvelles technologies et méthodes dans le domaine de la chimie des produits naturels a permis le développement de méthodes ‘high throughput’ pour la détermination de la composition chimique des extraits de plantes, l'évaluation de leurs propriétés et l'exploration de leur potentiel en tant que candidats médicaments. Dernièrement, la métabolomique, une approche intégrée incorporant les avantages des technologies d'analyse moderne et la puissance de la bioinformatique s’est révélé un outil efficace dans la biologie des systèmes. En particulier, l'application de la métabolomique pour la découverte de nouveaux composés bioactifs constitue un domaine émergent dans la chimie des produits naturels. Dans ce contexte, le genre Acronychia de la famille des Rutaceae a été choisi sur la base de son usage en médecine traditionnelle pour ses propriétés antimicrobienne, antipyrétique, antispasmodique et anti-inflammatoire. Nombre de méthodes chromatographiques modernes, spectrométriques et spectroscopiques sont utilisées pour l'exploration de leur contenu en métabolites suivant trois axes principaux constituant les trois chapitres de cette thèse. En bref, le premier chapitre décrit l’étude phytochimique d’Acronychia pedunculata, l’identification des métabolites secondaires contenus dans cette espèce et l'évaluation de leurs propriétés biologiques. Le deuxième chapitre vise au développement de méthodes analytiques pour l'identification des dimères d’acétophénones (marqueurs chimiotaxonomiques du genre) et aux stratégies utilisées pour la déréplication de ces différents extraits et la caractérisation chimique des composés par UHPLC-HRMSn. Le troisième chapitre se concentre sur l'application de méthodologies métabolomique (RMN et LC-MS) pour l'analyse comparative (entre les différentes espèces, origines, organes), pour des études chimiotaxonomiques (entre les espèces) et pour la corrélation des composés contenus avec une activité pharmacologique. / Medicinal plants constitute an unfailing source of compounds (natural products – NPs) utilised in medicine for the prevention and treatment of various deceases. The introduction of new technologies and methods in the field of natural products chemistry enabled the development of high throughput methodologies for the chemical composition determination of plant extracts, evaluation of their properties and the exploration of their potentials as drug candidates. Lately, metabolomics, an integrated approach incorporating the advantages of modern analytical technologies and the power of bioinformatics has been proven an efficient tool in systems biology. In particular, the application of metabolomics for the discovery of new bioactive compounds constitutes an emerging field in natural products chemistry. In this context, Acronychia genus of Rutaceae family was selected based on its well-known traditional use as antimicrobial, antipyretic, antispasmodic and anti-inflammatory therapeutic agent. Modern chromatographic, spectrometric and spectroscopic methods were utilised for the exploration of their metabolite content following three basic axes constituting the three chapters of this thesis. Briefly, the first chapter describes the phytochemical investigation of Acronychia pedunculata, the identification of secondary metabolites contained in this species and evaluation of their biological properties. The second chapter refers to the development of analytical methods for the identification of acetophenones (chemotaxonomic markers of the genus) and to the dereplication strategies for the chemical characterisation of extracts by UHPLC-HRMSn. The third chapter focuses on the application of metabolomic methodologies (LC-MS & NMR) for comparative analysis (between different species, origins, organs), chemotaxonomic studies (between species) and compound-activity correlations.
85

Etude de champs de température séparables avec une double décomposition en valeurs singulières : quelques applications à la caractérisation des propriétés thermophysiques des matérieux et au contrôle non destructif / Study of separable temperatur fields with a double singular value decomposition : some applications in characterization of thermophysical properties of materials and non destructive testing

Ayvazyan, Vigen 14 December 2012 (has links)
La thermographie infrarouge est une méthode largement employée pour la caractérisation des propriétés thermophysiques des matériaux. L’avènement des diodes laser pratiques, peu onéreuses et aux multiples caractéristiques, étendent les possibilités métrologiques des caméras infrarouges et mettent à disposition un ensemble de nouveaux outils puissants pour la caractérisation thermique et le contrôle non desturctif. Cependant, un lot de nouvelles difficultés doit être surmonté, comme le traitement d’une grande quantité de données bruitées et la faible sensibilité de ces données aux paramètres recherchés. Cela oblige de revisiter les méthodes de traitement du signal existantes, d’adopter de nouveaux outils mathématiques sophistiqués pour la compression de données et le traitement d’informations pertinentes. Les nouvelles stratégies consistent à utiliser des transformations orthogonales du signal comme outils de compression préalable de données, de réduction et maîtrise du bruit de mesure. L’analyse de sensibilité, basée sur l’étude locale des corrélations entre les dérivées partielles du signal expérimental, complète ces nouvelles approches. L'analogie avec la théorie dans l'espace de Fourier a permis d'apporter de nouveaux éléments de réponse pour mieux cerner la «physique» des approches modales.La réponse au point source impulsionnel a été revisitée de manière numérique et expérimentale. En utilisant la séparabilité des champs de température nous avons proposé une nouvelle méthode d'inversion basée sur une double décomposition en valeurs singulières du signal expérimental. Cette méthode par rapport aux précédentes, permet de tenir compte de la diffusion bi ou tridimensionnelle et offre ainsi une meilleure exploitation du contenu spatial des images infrarouges. Des exemples numériques et expérimentaux nous ont permis de valider dans une première approche cette nouvelle méthode d'estimation pour la caractérisation de diffusivités thermiques longitudinales. Des applications dans le domaine du contrôle non destructif des matériaux sont également proposées. Une ancienne problématique qui consiste à retrouver les champs de température initiaux à partir de données bruitées a été abordée sous un nouveau jour. La nécessité de connaitre les diffusivités thermiques du matériau orthotrope et la prise en compte des transferts souvent tridimensionnels sont complexes à gérer. L'application de la double décomposition en valeurs singulières a permis d'obtenir des résultats intéressants compte tenu de la simplicité de la méthode. En effet, les méthodes modales sont basées sur des approches statistiques de traitement d'une grande quantité de données, censément plus robustes quant au bruit de mesure, comme cela a pu être observé. / Infrared thermography is a widely used method for characterization of thermophysical properties of materials. The advent of the laser diodes, which are handy, inexpensive, with a broad spectrum of characteristics, extend metrological possibilities of infrared cameras and provide a combination of new powerful tools for thermal characterization and non destructive evaluation. However, this new dynamic has also brought numerous difficulties that must be overcome, such as high volume noisy data processing and low sensitivity to estimated parameters of such data. This requires revisiting the existing methods of signal processing, adopting new sophisticated mathematical tools for data compression and processing of relevant information.New strategies consist in using orthogonal transforms of the signal as a prior data compression tools, which allow noise reduction and control over it. Correlation analysis, based on the local cerrelation study between partial derivatives of the experimental signal, completes these new strategies. A theoretical analogy in Fourier space has been performed in order to better understand the «physical» meaning of modal approaches.The response to the instantaneous point source of heat, has been revisited both numerically and experimentally. By using separable temperature fields, a new inversion technique based on a double singular value decomposition of experimental signal has been introduced. In comparison with previous methods, it takes into account two or three-dimensional heat diffusion and therefore offers a better exploitation of the spatial content of infrared images. Numerical and experimental examples have allowed us to validate in the first approach our new estimation method of longitudinal thermal diffusivities. Non destructive testing applications based on the new technique have also been introduced.An old issue, which consists in determining the initial temperature field from noisy data, has been approached in a new light. The necessity to know the thermal diffusivities of an orthotropic medium and the need to take into account often three-dimensional heat transfer, are complicated issues. The implementation of the double singular value decomposition allowed us to achieve interesting results according to its ease of use. Indeed, modal approaches are statistical methods based on high volume data processing, supposedly robust as to the measurement noise.
86

Homology modeling and structural analysis of the antipsychotic drugs receptorome

López Muñoz, Laura 22 June 2010 (has links)
Classically it was assumed that the compounds with therapeutic effect exert their action interacting with a single receptor. Nowadays it is widely recognized that the pharmacological effect of most drugs is more complex and involves a set of receptors, some associated to their positive effects and some others to the side effects and toxicity. Antipsychotic drugs are an example of effective compounds characterized by a complex pharmacological profile binding to several receptors (mainly G protein-coupled-receptors, GPCR). In this work we will present a detailed study of known antipsychotic drugs and the receptors potentially involved in their binding profile, in order to understand the molecular mechanisms of the antipsychotic pharmacologic effects.The study started with obtaining homology models for all the receptors putatively involved in the antipsychotic drugs receptorome, suitable for building consistent drug-receptor complexes. These complexes were structurally analyzed and compared using multivariate statistical methods, which in turn allowed the identification of the relationship between the pharmacological properties of the antipsychotic drugs and the structural differences in the receptor targets. The results can be exploited for the design of safer and more effective antipsychotic drugs with an optimum binding profile. / Tradicionalmente se asumía que los fármacos terapéuticamente efectivos actuaban interaccionando con un único receptor. Actualmente está ampliamente reconocido que el efecto farmacológico de la mayoría de los fármacos es más complejo y abarca a un conjunto de receptores, algunos asociados a los efectos terapéuticos y otros a los secundarios y toxicidad. Los fármacos antipsicóticos son un ejemplo de compuestos eficaces que se caracterizan por unirse a varios receptores simultáneamente (principalmente a receptores unidos a proteína G, GPCR). El trabajo de la presente tesis se ha centrado en el estudio de los mecanismos moleculares que determinan el perfil de afinidad de unión por múltiples receptores de los fármacos antipsicóticos.En primer lugar se construyeron modelos de homología para todos los receptores potencialmente implicados en la actividad farmacológica de dichos fármacos, usando una metodología adecuada para construir complejos fármaco-receptor consistentes. La estructura de estos complejos fue analizada y se llevó a cabo una comparación mediante métodos estadísticos multivariantes, que permitió la identificación de asociaciones entre la actividad farmacológica de los fármacos antipsicóticos y diferencias estructurales de los receptores diana. Los resultados obtenidos tienen interés para ser explotados en el diseño de fármacos antipsicóticos con un perfil farmacológico óptimo, más seguros y eficaces.

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