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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.
1031

Zooarqueologia dos sítios arqueológicos Maracaju 1, MS e Santa Elina, MT / Zooarchaeology of the archaeological sites Maracaju 1, MS e Santa Elina, MT

Mirian Liza Alves Forancelli Pacheco 05 February 2009 (has links)
Vestígios arqueofaunísticos resgatados em sítios arqueológicos de Mato Grosso e Mato Grosso do Sul revelaram a existência pretérita de grupos humanos caçadores-coletores generalistas, nestes Estados. Inseridos neste contexto, estão os sítios arqueológicos Maracaju 1, MS e Santa Elina, MT, caracterizados por serem abrigos sob rocha, que apresentam painéis com inscrições rupestres, e por uma quantidade de remanescentes arqueofaunísticos, associados a outros vestígios da cultura material. Diante do exposto, o presente trabalho teve por objetivos (1) compreender, sob a perspectiva da arqueofauna, os padrões de subsistência das populações humanas pretéritas que ocuparam Maracaju 1, MS e Santa Elina, MT, dois abrigos em bioma de Cerrado; (2) delinear as atividades (específicas ou não) realizadas pelos grupos humanos que ocuparam estes abrigos; e, diante disso, (3) inferir a função destes abrigos para as populações pretéritas locais. Para tanto, estes registros zooarqueológicos foram estudados por meio de métodos e técnicas multidisciplinares (e.g. Taxonomia e Tafonomia experimental). Diante dos resultados deste trabalho, foi possível inferir que a caça e as atividades de subsistência, nas ocupações atribuídas aos caçadores-coletores, em Maracaju 1, ocorreram de modo sucessivo e, provavelmente, sazonal. Esta característica de ocupação fortaleceu a hipótese do elevado grau de mobilidade e das ocupações mais horizontalizadas na paisagem, característica desses grupos humanos. Do mesmo modo, a explicação mais parcimoniosa para o contexto zooarqueológico de Santa Elina, é a de que as ocupações humanas tiveram um caráter, provavelmente sazonal e ocorreram durante as alocações de recursos ligadas a outros eventos culturais, evidenciados pelos registros rupestres e pelos vestígios arqueológicos resgatados neste sítio. / Archaeofaunistic remains rescued in archaeological sites from Mato Grosso and Mato Grosso do Sul have shown the existence of generalists past hunter-gatherers groups in these states. Embedded in this context, there are the archaeological sites Maracaju 1, MS and Santa Elina, MT, characterized by being rock shelters, with rock art, and a quantity of archaeofaunistic remains, along with other traces of material culture. Facing the above, this work aimed to (1) understand, from the perspective of archaeofauna, the subsistence patterns of the people who occupied Maracaju 1, and Santa Elina, two shelters in the Cerrado biome, (2) outlining the activities (specific or not) done by human groups who occupied these shelters, and face it, (3) deduce the function of these shelters for local people. To reach that, these zooarchaeological records were studied using multidisciplinary methods and techniques (e.g. Taxonomy and Experimental taphonomy). Facing these results, it was possible to infer that hunting and subsistence activities, in occupations attributed to hunters-gatherers in Maracaju 1, occurred in successive and probably seasonal context. This occupation characteristic has strengthened the hypothesis of the high degree of mobility and more horizontalised occupations in the landscape, characteristic of these human groups. Similarly, the most parsimonious explanation for the zooarchaeological context of Santa Elina, is that the human occupation, probably had a seasonal character and occurred during the resources allocation related to other cultural events, evidenced by the rock art and the archaeological remains rescued in this site.
1032

O hipertexto como ponto de partida em processos de aprendizagem e criação da cena contemporânea

Cleber de Carvalho Lima 10 October 2013 (has links)
Esta pesquisa tem como objetivo investigar a proposição do hipertexto didático sobre poéticas cênicas contemporâneas como ponto de partida em processos de aprendizagem e de criação do teatro, utilizando como principal aporte metodológico a abordagem da pesquisaação fundamentada por Michel Thiollent. A revisão bibliográfica resultou na elaboração de um hipertexto didático (MARTINS, 2006), a ser publicado na internet, sobre o Teatro da Vertigem (São Paulo), produzindo um material hipertextual e multimodal para uso pedagógico, que articula textos teóricos, análises críticas, registros de espetáculos e processos, depoimentos dos artistas, descrição e análise de procedimentos de criação e fragmentos de dramaturgia. A realização e a análise de dois experimentos de aprendizagem e encenação realizados na cidade de Campo Limpo Paulista (SP), com um grupo de iniciantes em teatro e outro formado por atores amadores na faixa etária de 18 a 42 anos, permitiu a sistematização de princípios e procedimentos metodológicos de ensino e aprendizagem do teatro contemporâneo. O jogo teatral a partir de modelos estéticos (KOUDELA, RYNGAERT, PUPO, MARTINS) e procedimentos da abordagem colaborativa desenvolvida por ARAÚJO, são os eixos norteadores das práticas de criação propostas nos experimentos realizados a partir do hipertexto didático criado pelo coordenador e ampliado pelos participantes. A seleção das referências teóricas se deu a partir da perspectiva de teóricos do teatro contemporâneo como LEHMANN, FERRAL, FERNANDES, ARAÚJO, PAVIS e SARRAZAC. Os resultados obtidos poderão contribuir para o debate acerca de abordagens metodológicas que integrem estudos teóricos e históricos com práticas colaborativas de criação da cena e que possam interessar para professores, coordenadores de oficinas e encenadores envolvidos na reflexão a cerca dos processos de aprendizagem e criação da cena contemporânea. / This work investigates the proposition of hypertext courseware on contemporary scenic poetic elements as a starting point for theater creation and learning processes, having primarily relied, as a methodological input, on Michel Thiollent\'s action-research approach. The bibliographical review has resulted in hypertext courseware (MARTINS, 2006), to be published on the internet, about Teatro da Vertigem (São Paulo), having thus generated a multimode, hypertext material for educational use, which puts together theoretical texts, critical reviews, records of spectacles and processes, testimonials of artists, a description and analysis of creation processes and procedures, and figments of theater practice. The conduction and analysis of two learning and staging experiments held in the city of Campo Limpo Paulista (São Paulo, Brazil), comprising a group of theater novices and another group made up of amateur actors aged 18 to 42, allowed me to systematize some learning principles and methodologies of the contemporary theater. The theater game based on esthetic frameworks (KOUDELA, RYNGAERT, PUPO, MARTINS) as well as on collaborative approach procedures devised by ARAÚJO are the guiding pillars for the creation practices proposed during the experiments based on the educational hypertext as devised by the coordinator and further expanded by the players. Selection of theoretical references has drawn on such contemporary theater theorists as LEHMANN, FERRAL, FERNANDES, ARAÚJO, PAVIS, and SARRAZAC. The results may contribute to debates over the methodological approaches that bring together theoretical and historical studies, on one part, and collaborative staging practices, which might be useful for teachers, workshop coordinators and stage directors involving in a reflection over the contemporary theater creation and learning processes.
1033

Levantamento arqueológico na reserva de desenvolvimento sustentável (RDS) Amanã: Estado do Amazonas / Archaeological Survey at SDR-Amanã Amazonas State

Bernardo Lacale Silva da Costa 05 December 2012 (has links)
Este trabalho apresenta os resultados preliminares de levantamento arqueológico realizado na RDS Amanã, Estado do Amazonas. Situada na região do médio curso do rio Solimões e baixo Japurá, a RDS Amanã está na fase de preparo do seu plano de gestão. A respeito do Patrimônio Arqueológico existente na reserva Amanã 32 sítios arqueológicos formados por terra preta, cerâmica e material lítico polido foram identificados em etapas de levantamento realizadas entre 2006 e 2008. Levando em consideração o tamanho, densidade e variabilidade dos vestígios arqueológicos, assim como, a intensidade dos processos pós-deposicionais os sítios Boa Esperança e Bom Jesus do Baré foram escolhidos para realização de mapeamentos e escavação. O objetivo principal desse mestrado é apresentar o contexto arqueológico da reserva Amanã a partir de uma perspectiva comparativa com pesquisas arqueológicas que ocorrem em outros locais da Amazônia. Mais especificamente com a cronologia estabelecida para as ocupações ceramistas na Amazônia Central e áreas adjacentes, como Baixo Amazonas e médio Rio Caquetá/Japurá. A partir de dados relativos ao tamanho, composição, formato e estratigrafia dos sítios, assim como analise cerâmica e datações é formulada uma cronologia preliminar para o lago Amanã. / The main goal of this dissertation is to introduce the archaeological context of the Amanã Sustainable Development Reserve, situated near the middle course of the Amazon and the lower course of the Japurá Rivers, in the state of Amazonas; its management plan is currently under preparation. This context is then compared to the archaeology of other areas of Amazonia. Preliminary results of the archaeological survey carried out between 2006 and 2008 will be presented, during which time 32 archaeological sites were identified. These are composed of anthropogenic dark earth, pottery and ground lithics. The Boa Esperança and Bom Jesus do Baré archaeological sites were selected for mapping and excavation due to their size, density and the variability of archaeological material they contain. An initial chronology for the Amanã Lake is put forward, based on data related to site size, composition, form and stratigraphy. This is then contrasted to ceramicist occupations identified in the Central Amazon and adjacent areas (the Lower Amazon and middle Caquetá/Japurá). Such a comparative approach is employed as a tool to allow the insertion of the Amanã Lake in the wider scenario, in this way allowing for a contribution to debates and discussions that are important to Amazonian Archaeology, such as the origin and dispersal of ceramic traditions. The data will further provide information to be utilized with local inhabitants for the future development of research, public archaeology and the reserve\'s management activities.
1034

Optimization of a tool to study the start-up of the gas phase olefin polymerization / Optimisation d'un outil pour l'étude des premiers instants de la polymérisation des oléfines en phase gazeuse

Tioni, Estevan 14 December 2011 (has links)
La phase initiale (de quelque fractions de seconde à quelques minutes) de la polymérisation catalytique des oléfines est encore peu comprise. Elle est pourtant reconnue comme une étape cruciale pour contrôler la morphologie de la particule de polymère et pour garantir la performance optimale du catalyseur et une certaine stabilité thermique du procédé. Ce travail présente l'étude et l'optimisation d'un mini réacteur à lit fixe pour mener des polymérisations catalytiques en phase gaz avec des durées très faibles (minimum 0.1s) dans des conditions proches à celles utilisées industriellement. La possibilité de suivre la température du gaz et de récupérer les particules de polymère pour les caractériser permet de décrire d'une façon complète le comportement du catalyseur au début de la réaction. L'étude a été limitée à la polymérisation de l'éthylène (avec un catalyseur métallocène supporté sur silice) et l'attention a été particulièrement mise sur la relation entre transfert de chaleur de la particule et performance du catalyseur. Il a été montré que des températures trop élevées peuvent être responsable localement de la modification du comportement du site active et de l'altération des propriétés des polymères. Un choix adéquat des conditions de réaction permet de suivre indirectement l'évolution de la température des particules en mesurant celle de la phase gaz. Dans un deuxième temps différents métallocènes ont été utilisés pour étudier l'influence des conditions de réaction, de la préparation du catalyseur et des propriétés du support sur l'activité, les propriétés du polymère et la morphologie des particules au temps court. Une attention particulière a été portée sur l'évolution des sites actifs et sur la cristallisation des chaînes de polymère dans un support poreux en évolution. Une activité élevée a été mesurée dans les premières cinq secondes et les températures de fusion et cristallisation des polymères ont été utilisées comme sondes pour mesurer l'avancement de la fragmentation du support. Les résultats ainsi obtenus peuvent non seulement clarifier certains aspects clé du début de la polymérisation mais aussi être utilisés comme donnés de départ pour modéliser la particule en croissance et contribuer à réduire l'écart qui est actuellement présent entre comportement réel du catalyseur et prédictions des modèles / The early stages (from less than 1s to few minutes) of catalytic olefin polymerization are still fairly understood even if they are nowadays recognized to be crucial for the determination of the morphology of the polymer particle, the optimization of the whole catalyst performance and the thermal stability of the process. In this work we will present how we studied and optimized a specially conceived packed bed reactor to perform gas phase catalytic olefin polymerizations as short as 0.1s under industrially relevant conditions. The possibility to measure the reactor temperature and to recover unaltered the polymer particles allows to take a complete picture of the catalyst behavior at the reaction start-up. The study will be restrained to ethylene polymerization with silica supported metallocenes and special attention will be given to the relation between heat transfer from the growing particle and catalyst performance. It will be seen how particle temperature evolution can be followed indirectly by measuring the gas phase temperature .In the second part of this work different metallocene complexes will be used to study the influence of process conditions, catalyst preparation method and support properties on the evolution of reaction rate, and polymer MWD during the first reaction seconds. Special attention will be given to the active site evolution during the transient phase and it will be shown that temperature excursions can be responsible for a local variation in active site behavior thus altering the properties of the formed polymer. The last section will be dedicated to the study of the peculiar crystallization behavior of the polymer chains in an evolving inorganic support. It will be shown how the melting and crystallization temperatures of the polymers can be used as “sensors” to measure the degree of fragmentation of the support particle. The results obtained in this work allow to gain a deeper understanding of the key parameters for the polymerization start-up and can be used as input for single particle models thus allowing to reduce the gap actually present between real catalyst behavior and model predictions
1035

Rôle des facteurs de l’hôte dans le maintien des prophages chez les entérobactéries / Host factors involvement in prophage maintenance in Enterobacteriaceae

Delannoy, Maëlle 15 December 2016 (has links)
Les prophages sont des vecteurs majeurs de l’évolution des génomes bactériens et ont des rôles divers dans le processus adaptatif de leurs hôtes et peuvent leur apporter un avantage sélectif. Au cours de l’évolution, certains gènes prophagiques peuvent être perdus, notamment ceux codant pour des protéines du cycle lytique. Cependant, alors que certains de ces prophages défectifs sont capables de s’exciser, ils sont maintenus dans le génome de l’hôte, suggérant une pression sélective pour les conserver. C’est le cas du prophage défectif KplE1 chez E. coli K12. Dans l’équipe, des travaux ont mis en évidence que le maintien en lysogénie de différents prophages était sous le contrôle du terminateur de la transcription bactérien Rho. Afin d’identifier de nouveaux facteurs de l’hôte impliqués dans le maintien des prophages, j’ai développé un crible génétique qui m’a permis d’identifier plusieurs candidats impliqués dans le métabolisme général, la détoxification du NO ou qui appartiennent à un autre prophage défectif. Mon travail a été de discriminer lesquels de ces candidats jouaient un rôle significatif dans le maintien des prophages. Sur les trois gènes impliqués dans la détoxification du NO, seule l’expression de norV ou norW permet le maintien de KplE1. NorV réduit le NO et cette réduction nécessite l’utilisation d’un électron généré par l’oxydation du NADH par NorW. J’ai pu également montrer que l’expression du gène norV permettait le maintien d’un autre prophage fonctionnel (HK620) partageant le même module de recombinaison spécifique de site que KplE1. L’ensemble de mes résultats montre qu’il existe un lien co-évolutif important entre les prophages et leurs hôtes. / Prophages play recognized roles in their host genomes evolution and adaptation to variable ecosystems. They can provide to their host selective advantages that increase their competitiveness. Upon evolution, some prophage genes can be lost, especially those coding for lytic cycle capacity. While some of the defective prophages are perfectly competent for excision, they prove to be maintained in bacterial genomes, suggesting the involvement of a selective pressure. This is the case for our defective prophage model: KplE1 in E. coli K12. Previous work in our laboratory demonstrated that lysogeny maintenance of various prophages was controlled by Rho which is the bacterial transcription termination factor. In order to identify new host factors involved in prophage maintenance, I developed a genetic screen. This screen allowed me to identify candidate genes involved in bacterial general metabolism, in NO detoxification and also some genes that belong to another defective prophage. I determined which candidate genes actually played a role in KplE1 maintenance. Among the three genes involved in NO detoxification, I showed that norV or norW individual expression allowed KplE1 maintenance. NorV reduces NO and this reduction needs an electron produced by NorW NADH oxidation. I also showed that norV expression allowed the maintenance of another functional prophage (HK620) that shares the same site specific recombination module as KplE1. Together, my results illustrate the coevolution between prophages and their hosts.
1036

wireless site survey : site surveying in home,office and laboratory environment

Nail, Haidar January 2011 (has links)
Today, Communication has increasing influence on our Daily life. Wireless data Communication services allow people to access the data Network without a physical Connection. This work Studying Wireless Local Area Network WLAN features and describing all technologies and standard necessary to operate this network. This work aims also at comprehensive investigation of wireless network including wireless Local Area Networks implementation and performance analysis. Testing WLAN performance through some practical measurement such as site surveying in different locations, finally measuring the strength of the signals different locations in the coverage area, test results can be used in order to enhance the network performance.
1037

Generating web applications containing XSS and CSRF vulnerabilities

Ahlberg, Gustav January 2014 (has links)
Most of the people in the industrial world are using several web applications every day. Many of those web applications contain vulnerabilities that can allow attackers to steal sensitive data from the web application's users. One way to detect these vulnerabilities is to have a penetration tester examine the web application. A common way to train penetration testers to find vulnerabilities is to challenge them with realistic web applications that contain vulnerabilities. The penetration tester's assignment is to try to locate and exploit the vulnerabilities in the web application. Training on the same web application twice will not provide any new challenges to the penetration tester, because the penetration tester already knows how to exploit all the vulnerabilities in the web application. Therefore, a vast number of web applications and variants of web applications are needed to train on. This thesis describes a tool designed and developed to automatically generate vulnerable web applications. First a web application is prepared, so that the tool can generate a vulnerable version of the web application. The tool injects Cross Site Scripting (XSS) and Cross Site Request Forgery (CSRF) vulnerabilities in prepared web applications. Different variations of the same vulnerability can also be injected, so that different methods are needed to exploit the vulnerability depending on the variation. A purpose of the tool is that it should generate web applications which shall be used to train penetration testers, and some of the vulnerabilities the tool can inject, cannot be detected by current free web application vulnerability scanners, and would thus need to be detected by a penetration tester. To inject the vulnerabilities, the tool uses abstract syntax trees and taint analysis to detect where vulnerabilities can be injected in the prepared web applications. Tests confirm that web application vulnerability scanners cannot find all the vulnerabilities on the web applications which have been generated by the tool.
1038

Mesure et modélisation de la lumière naturelle dans les canyons urbains / Daylight measurement and modelling in urban canyons

Patriarche, Manolis 08 September 2014 (has links)
L’augmentation de la population mondiale et l’urbanisation croissante conduisent à une densification urbaine qui menace l’accès des habitants des villes au soleil et à la lumière naturelle. Cet accès est lié à des problématiques de consommation d’énergie, de santé et de bien-être ; il peut être limité par plusieurs caractéristiques du tissu urbain telles que la largeur des rues, la hauteur des bâtiments, la clarté des façades et de la chaussée. Nous avons étudié l’influence des caractéristiques les plus importantes d’un canyon urbain sur la disponibilité de la lumière naturelle à l’intérieur du canyon sous des conditions climatiques réelles. Nous avons fabriqué dans ce but, le modèle réduit d’un canyon urbain, la représentation simplifiée d’une rue. Cette maquette est modifiable, le rapport d’aspect H/W (Hauteur/Largeur) du canyon peut être modifié et les façades sont interchangeables. Durant une année, les éclairements lumineux y ont été mesurés sur le sol et à plusieurs hauteurs des façades, au pas de la minute, sous des conditions de ciel réelles. Au total, 12 configurations sont représentées dans la base de données obtenue, avec 3 rapports d’aspect : H/W=0,5, 1 et 2, et 4 types de façades de facteur de réflexion lumineux différent. Les revêtements de façade utilisés sont : noir, blanc, crépi et crépi avec des parties vitrées. Nous étudions l’influence de ces paramètres en fonction des types de ciel définis par la CIE pour un canyon orienté nord/sud. Nous utilisons aussi ces données pour étudier l’usage, la performance et la précision de trois logiciels de modélisation du rayonnement solaire en milieu urbain : Citysim, Daysim et Heliodon. Ces trois logiciels offrant différents niveaux de simplification. Enfin, nous avons mené une campagne de mesure dans les rues de Lyon. Cela nous a permis de nous confronter à la réalité des données de terrain, juger des difficultés à les recueillir et à modéliser le rayonnement solaire dans l'espace réel. Nous avons aussi évalué une nouvelle méthode de mesure des éclairements lumineux d’une façade. Cette méthode se base sur des cartes de luminances obtenues à partir de photos fisheye avec un appareil photo numérique étalonné en luminances. La comparaison de ces mesures avec celles de la maquette permet d’évaluer l’erreur commise en utilisant un revêtement simplifié. En utilisant les données récoltées sur la maquette, le rapport d’aspect H/W=1 permet d’obtenir le meilleur accès à la lumière naturelle dans le canyon, il correspond à un bon compromis entre la contribution des façades et du ciel. Pour chaque ville, une configuration optimale peut être déterminée en fonction du climat local, qui peut être représenté par la fréquence d’observation des différents types de ciel CIE. Nous avons évalué la capacité des logiciels choisis à prendre en compte le climat. Avec Heliodon, il est possible d’obtenir des éclairements lumineux proches de ceux mesurés sur la maquette, pour des ciels sans nuages. Puisque le climat varie tout au long de l’année, la prise en compte des 15 types de ciel CIE doit être préférée à l’utilisation d’un ciel uniquement sans nuages, ou couvert comme cela est souvent le cas. Les logiciels Citysim et Daysim sont capables de prendre en compte le climat réel et produisent de bonnes corrélations avec les mesures effectuées sur la maquette pour tous les types de ciel. / As the world population and the urbanization increase, cities become denser, thus reducing access to daylight and sunlight for city dwellers. This access is linked to some issues such as energy consumption, health and comfort; it can be limited by several urban fabric features such as street width, building height, façade and road coating. We have evaluated the influence of the most important features of an urban canyon regarding daylight availability inside the canyon under real sky conditions.To that end, we have built a scale model of an urban canyon, the simplest representation of a street. This scale model can be modified: the aspect ratio H/W (Height/Width) can be changed as well as the type of façade. During one year, outdoor illuminances have been measured every minute on the ground and at different heights of the façades. Hence, we created a database containing twelve combinations of an urban canyon with the following parameters: three aspect ratios (H/W=2, 1 and 0.5) and four types of façades with different reflection factors. The different coatings of the façades are: black, white, roughcast and roughcast with windows. We evaluate the influence of these parameters for each type of sky defined according to the CIE for a north/south orientated canyon.We also use this database in order to evaluate the ease of use, performance and precision of three software tools for the estimation of solar radiation in urban context: Citysim, Daysim and Heliodon, each having different simplification levels.Finally, we have carried a measuring campaign in the streets of the French city of Lyons. This campaign allowed us to realize the difficulty of collecting data in the field and modelling solar radiation of a real street. We have also assessed a new method for measuring illuminances of a whole façade. This method is based on a luminance map generated from a calibrated digital camera equipped with a fisheye lens. A comparison between these illuminances with illuminances measured on the scale model with regular sensors allows us to estimate the bias of using a simplified coating.Based on illuminances measured on the scale model, a canyon with an aspect ratio H/W=1 has a better access to daylight, it represents a good compromise between contributions of the sky and the opposing façade. Every city has an optimal canyon shape according to its local climate that could be defined as the frequency of occurrence of the CIE types of sky. We have evaluated the ability of the selected software tools to take into account the climate. For clear skies, Heliodon is able to produce illuminances close to those measured on the scale model. Because the weather changes throughout the year, one would rather take into account the 15 CIE types of sky instead of using either a clear sky or an overcast sky as many studies do. Citysim and Daysim are able to take into account the climate and correlate well with scale model measurements for each type of sky. The method for measuring illuminances using a fisheye lens camera has been validated based on the measurements in real streets of Lyons. This method could produce more accurate values using a reflection factor map of the façade. Illuminances measured on the scale models didn’t correlate well with illuminances measured in real streets because of the complexity of the streets compared to the simplicity of the idealized canyon of the scale model. The use of simplified models of streets can lead to bad results, for instance, with studies estimating the energy consumption of buildings for lighting at district or urban scale. The density of urban areas must decrease in order to improve access to daylight. That would provide other advantages such as the reduction of exposure to vehicles pollution or reduction of the urban heat island. The calculation of an ideal aspect ratio could be achieved using tools evaluated in this thesis.
1039

Characterization of natural product biological imprints for computer-aided drug design applications / Caractérisation de l’empreinte biologique des produits naturels pour des applications de conception rationnelle de médicament assistée par ordinateur

Sturm, Noé 08 December 2015 (has links)
La comparaison de site peut-elle vérifier l’hypothèse: «Les origines biosynthétiques des produits naturels leurs confèrent des activités biologiques»? Pour répondre à cette question, nous avons développé un outil modélisant les propriétés accessibles au solvant des sites de liaison. La méthode a montré des aspects intéressants, mais elle souffre d’une sensibilité aux coordonnées atomiques. Cependant, des méthodes existantes nous ont permis de prouver que l’hypothèse est valide pour la famille des flavonoïdes. Afin d’étendre l’étude, nous avons développé un procédé automatique capable de rechercher des structures d’enzymes de biosynthèse de produits naturels disposant de sites actifs capables de lier une molécule de petite taille. Nous avons trouvé les structures de 117 enzymes.Les structures nous ont permis de caractériser divers modes de liaison substrat-enzyme, nous indiquant l’empreinte biologique des produits naturels ne correspond pas toujours au modèle « clé- serrure ». / Can computational binding site similarity tools verify the hypothesis: “Biosynthetic moldings give potent biological activities to natural products”? To answer this question, we designed a tool modeling binding site properties according to solvent exposure. The method showed interesting characteristics but suffers from sensitivity to atomic coordinates. However, existing methods have delivered evidence that the hypothesis was valid for the flavonoid chemical class. In order to extend the study, we designed an automated pipeline capable of searching natural products biosynthetic enzyme structures embedding ligandable catalytic sites. We collected structures of 117 biosynthetic enzymes. Finally, according to structural investigations of biosynthetic enzymes, we characterized diverse substrate-enzyme binding-modes, suggesting that natural product biological imprints usually do not agree with the “key-lock” model.
1040

Investigation of enzymes from the respiratory chain by using electrochemical and spectroscopic techniques / Etude des enzymes de la chaîne respiratoire caractérisées par électrochimie et spectroscopie

Sabuncu, Sinan 09 May 2017 (has links)
Le présent travail porte sur l’étude de deux protéines de la famille des oxydases à hème-fer par des techniques de spectroscopie et d’électrochimie. Le premier chapitre décrit l’étude du cytochrome bo3 oxydase issue d’E. coli. Nous nous sommes intéressés à l’étude des interactions enzyme-quinone par l’utilisation de quinones avec des longueurs chaines isoprenyl différentes. Notre but est de mieux comprendre le rôle de la longueur de la chaine des quinones sur l’activité catalytique de l’enzyme et sur les propriétés redox des cofacteurs à hème. Dans l’étape suivante, on a étudié les résidus impliqués dans le site de liaison des quinones (haute affinité, QH). Plusieurs mutations de ces résidus sont étudiées pour mieux comprendre l’importance de chacun des résidus dans cette liaison. Dans la dernière partie de ce premier chapitre, la spectroscopie SEIRAS «spectroscopie d’absorption infrarouge exaltée de surface» est introduite comme une technique alternative pour l’étude des protéines membranaires. Dans le second chapitre, la protéine membranaire cNOR issue de P. denitrificans est étudiée. Nous nous sommes focalisés sur l’effet de différents environnements (pH, présence de protéo-liposomes) sur la stabilité de la cNOR. Pour ce faire, trois valeurs de pH (6.5, 7.5 et 8.5) sont choisies et quelques échantillons de cNOR sont reconstitués dans des protéo-liposomes. Enfin, le donneur de proton terminal (au centre binucléaire) dans la protéine cNOR était étudié. De plus, nous avons étudié les ligands des ions Ca2+ puisqu’il est proposé que le donneur de proton est situé proche de cette région. / This thesis is focused on the study of two members of the heme-copper oxidase family by using spectroscopic and electrochemical techniques. In the first chapter cytochrome bo3 oxidase from E. coli was studied. We focused on the quinone-enzyme interactions by using quinones with different isoprenyl chains. Our aim was to better understand the role of isoprenyl chain on the catalytic activity of the enzyme and the redox properties of the heme cofactors. In the next step we studied the residues that are suggested to be in the high-affinity (QH) quinone binding site. Several site-directed mutants of these residues were investigated in order to better understand the position of QH binding site and the importance of each residue. In the last part of this chapter surface-enhanced infrared absorption spectroscopy (SEIRAS) was introduced as an alternative technique to study the membrane proteins. In the second chapter cytochrome c dependent nitric oxide reducates (cNOR) from P. denitrificans was studied. We focused on the effect of different environment (pH, proteoliposomes) on the stability of cNOR. For that purpose three pH values (6.5, 7.5 and 8.5) was selected and some of the cNOR samples were reconstituted in liposomes. Finally, the terminal proton donor (to the binuclear center) in cNOR was investigated. We studied the ligands of the Ca2+ site in cNOR since it was suggested that the proton donor may be close to this area.

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