Gangschwärme nehmen eine bedeutende Stellung im Verständnis zur kontinentalen Fragmentierung ein. Einerseits markieren sie das Paläo-Spannungsfeld und helfen bei der Rekonstruktion der strukturellen Entwicklung der gedehnten Lithosphäre, andererseits gibt ihre petrologische Beschaffenheit Aufschluß über die Entstehung des Magmas, Aufstieg und Platznahme und schließlich erlaubt ihre Altersbestimmung die Rekonstruktion einer chronologischen Reihenfolge magmatischer und struktureller Ereignisse.<br><br> Das Arbeitsgebiet im namibianischen Henties Bay-Outjo Dike swarm (HOD) war zur Zeit der Unterkreide einem Rifting mit intensiver Platznahme von überwiegend mafischen Gängen unterworfen. Geochemische Signaturen weisen die Gänge als erodierte Förderkanäle der Etendeka Plateaubasalte aus. Durch den Einsatz von hochauflösenden Aeromagnetik- und Satellitendaten war es möglich, die Geometrie des Gangschwarmes erstmals detailliert synoptisch zu erfassen. Viele zu den Schichten des Grundgebirges foliationsparallel verlaufende magnetische Anomalien können unaufgeschlossenen kretazischen Intrusionen zugeordnet werden.<br><br> Bei der nach Norden propagierenden Südatlantiköffnung spielte die unterschiedliche strukturelle Vorzeichnung durch die neoproterozoischen Faltengürtel sowie Lithologie und Spannungsfeld des Angola Kratons eine bedeutende Rolle. Im küstennahen zentralen Bereich war dank der Vorzeichnung des Nordost streichenden Damara-Faltengürtels ein Rifting in Nordwest-Südost-Richtung dominierend, bis das Angola Kraton ein weiteres Fortscheiten nach Nordosten hemmte und die Vorzeichnung des Nordwest streichenden Kaoko-Faltengürtels an der Westgrenze den weiteren Riftverlauf und die letztendlich erfolgreiche Öffnung des Südatlantiks bestimmte. Aus diesem Grund kann das Gebiet des HOD als ein failed rift betrachtet werden.<br><br> Die Entwicklung des Spannungsfeldes im HOD kann folgendermaßen skizziert werden:<br><br> 1. Platznahme von Gängen bei gleichzeitig hoher Dehnungsrate und hohem Magmenfluß.<br> 2. Platznahme von Zentralvulkanen entlang reaktivierter paläozoischer Lineamente bei Abnahme der Dehnungsrate und fortbestehendem hohen Magmenfluß.<br> 3. Abnahme/Versiegen des Magmenflusses und neotektonische Bewegungen führen zur Bildung von Halbgräben. / Dike swarms play a fundamental role in understanding continental breakup. On the one hand they represent strain markers of the paleo-deformation field and help to reconstruct the structural evolution of the rifted lithosphere. On the other hand their magmatic infill contains information about the conditions of magma generation, ascent and emplacement. Finally, dating of dikes allows reconstructing a chronological order of magmatic and structural events. The study area of the Namibian Henties Bay-Outjo Dike swarm (HOD) underwent tectonic extension in the Lower Cretaceous associated with the widespread emplacement of predominantly mafic dikes and intrusive ring complexes representing the remnants of volcanic centres. Geochemical signatures of the dikes prove them to be the feeder structures of the Etendeka Plateau Basalts. The application of recent high resolution aeromagnetic surveys and satellite imaging revealed the dike swarm's extent and geometry for the first time. The distribution and geometry of the dikes shown in the aeromagnetics reflect the propagation of the South Atlantic opening from south to north by their relative-ages.<br><br> Northwest-southeast-directed rifting was dominant in the central coastal area, due to the structural control of the northeast striking basement structures until further propagation was hampered by the Angola Craton. Subsequently the structural control of the coast-parallel Kaoko Belt became dominant and determined the successful opening of the South Atlantic. Hence, the area of the HOD can be considered as a failed rift.<br><br> The stress field evolution within the HOD can be outlined as follows:<br><br> 1. Intrusion of dikes when extension rates as well as magma supply were high.<br> 2. Intrusion of volcanic ring complexes along reactivated Panafrican lineaments when extension rates decreased and magma supply remained high.<br> 3. Neotectonic movements create half-grabens after the termination of magmatism.

Made available in DSpace on 2015-03-13T17:08:24Z (GMT). No. of bitstreams: 1 HugoRCG_1_65pdf.pdf: 4964463 bytes, checksum: cd795f8d072464fe6d6ecf3458754e80 (MD5) Previous issue date: 2009-09-28 / A complex depositional history, related to Atlantic rifting, demonstrates the geological evolution during the late Jurassic and early Neocomian periods in the Araripe Basin NE Brazil. Based on outcrop, seismic and remote sensing data, a new model of the tectono-stratigraphic evolution of the section that covers the stages Dom Jo?o, Rio da Serra and Aratu (Brejo Santo, Miss?o Velha and Abaiara formations) is presented in this paper. In the stratigraphic section studied, ten sedimentary facies genetically linked to nine architectural elements were described, representing depositional systems associated with fluvial, aeolian and deltaic environments. Based on the relationship between the rates of creation of accommodation space and sediment influx (A / S) it was possible to associate these depositional systems with High and Low accommodation system tracks. These system tracks represent two tectono-sequences, separated by regional unconformities. The Tectono-sequence I, which includes lithotypes from the Brejo Santo Formation and is related to the pre-rift stage, is bounded at the base by the Paleozoic unconformity. This unit represents only a High Accommodation System Track, composed by a succession of pelitic levels interbedded with sandstones and limestones, from a large fluvial floodplain origin, developed under arid climatic conditions. The Tectono-sequence II, separated from the underlying unit by an erosional unconformity, is related to the rift stage, and is composed by the Miss?o Velha and Abaiara Formation lithotypes. Changes in depositional style that reflect variations in the A / S ratio, and the presence of hydroplastic deformation bands, make it possible to divide this tectonosequence into two internal sequences. Sequence IIA, which includes the lower portion of the Miss?o Velha Formation and sequence IIB, is composed by the upper section of the Miss?o Velha and Abaiara Formations The Sequence IIA below, composed only by the Low Accommodation System Track, includes crossbedding sandstones interbedded with massive mudstones, which are interpreted as deposits of sandy gravel beds wandering rivers. Sequence IIB, above, is more complex, showing a basal Low Accommodation System Track and a High Accommodation System Track at the top, separated by an expansion surface. The lower System Track, related to the upper portion of the Miss?o Velha Formation, is composed by a series of amalgamated channels, separated by erosion surfaces, interpreted as deposits of a belt of braided channels. The High Accommodation System Track, correlated with the Abaiara Unit, is marked by a significant increase in the A / S, resulting in the progradation of a system of braided river deltas with aeolic influence. Regarding tectonic evolution, the stratigraphic study indicates that the Tectonosequence Rift in the Araripe basin was developed in two phases: first characterized by a beginning of rifting, related to Sequence IIA, followed by a phase of syndepositional deformation, represented by sequence IIB. The first phase was not influenced by the development of large faults, but was influenced by a sharp and continuous decrease of accommodation space that permitted a change in depositional patterns, establishing a new depositional architecture. In turn, the stage of syndepositional deformation allowed for the generation of enough accommodation space for the preservation of fluvial-lacustrine deposits and conditioned the progradation of a braided river-dominated delta system. / Uma complexa hist?ria deposicional, relacionada ao rifteamento do Atl?ntico, caracteriza a evolu??o geol?gica durante o final do Jur?ssico e o in?cio do Neocomiano na Bacia do Araripe, NE do Brasil. Com base na integra??o de dados de afloramentos, se??es s?smicas e sensores remotos, apresenta-se neste trabalho, um novo modelo de evolu??o tectono-estratigr?fica para a se??o que compreende os andares Dom Jo?o, Rio da Serra e Aratu (forma??es Brejo Santo, Miss?o Velha e Abaiara). Na se??o estudada foram descritas dez f?cies sedimentares que associadas geneticamente constituem nove elementos arquiteturais, que integram sistemas deposicionais de origem fluvial, e?lica e deltaica. Com base na rela??o entre as taxas de acomoda??o e aporte sedimentar (rela??o A/S) foi poss?vel associar estes sistemas deposicionais aos tratos de sistemas de Alta e Baixa Acomoda??o. Estes tratos de sistemas integram duas tectonosseq??ncias, as quais est?o separadas por discord?ncias regionais. A Tectonosseq??ncia I ? composta pelos lit?tipos da Forma??o Brejo Santo e se relaciona ao Est?gio Pr?-Rifte, sendo limitada na base pela Discord?ncia Paleoz?ica. Tal unidade ? formada apenas pelo Trato de Sistemas de Alta Acomoda??o, caracterizado por uma sucess?o de n?veis pel?ticos intercalados a arenitos e calc?rios, originados a partir de uma ampla plan?cie fluvial distal, desenvolvida em condi??es de clima ?rido. A tectonosseq??ncia II, separada da seq??ncia sotoposta por uma discord?ncia erosiva, relaciona-se ao Est?gio Rifte, sendo composta pelos lit?tipos das forma??es Miss?o Velha e Abaiara. Mudan?as no estilo deposicional que refletem varia??es na rela??o A/S, al?m da presen?a de bandas de deforma??o hidropl?sticas, permitiram compartimentar tal tectonosseq??ncia em duas seq??ncias internas. Seq??ncia IIA, associada ? por??o inferior da Forma??o Miss?o Velha, e Seq??ncia IIB, formada pela se??o superior da Forma??o Miss?o Velha e pela Forma??o Abaiara. A Seq??ncia IIA, caracterizada somente pelo Trato de Sistemas de Baixa Acomoda??o, ? composta por arenitos com estratifica??es cruzadas intercalados a pelitos interpretados como dep?sitos de um sistema fluvial meandrante grosso. A Seq??ncia IIB, acima, ? mais complexa, sendo formada pelos tratos de sistemas de Baixa Acomoda??o, basal, e de Alta Acomoda??o, superior, separados por uma superf?cie de expans?o. O trato de sistemas basal, relacionado ? por??o superior da Forma??o Miss?o Velha, ? composto por uma s?rie de canais amalgamados, separados por superf?cies de eros?o, interpretados como dep?sitos de um cintur?o de canais entrela?ados. O Trato de Sistemas de Alta Acomoda??o, correlacionado ? Forma??o Abaiara, ? marcado por um aumento significativo na rela??o A/S, que propiciou a prograda??o de um sistema de deltas de rios entrela?ados, com influ?ncia e?lica. No que tange ? evolu??o tect?nica, o estudo estratigr?fico aqui efetuado trouxe ? tona que a Tectonosseq??ncia Rifte na Bacia do Araripe desenvolveu-se segundo duas fases distintas: uma fase de in?cio do rifte, relacionada ? Seq??ncia IIA, seguida de uma fase de deforma??o sindeposicional, representada pela Seq??ncia IIB. A primeira fase n?o foi condicionada pelo desenvolvimento de grandes falhamentos e, sim, por uma diminui??o abrupta e cont?nua do espa?o de acomoda??o que propiciou uma mudan?a nos padr?es deposicionais estabelecendo assim uma nova arquitetura deposicional. Por sua vez, a fase de deforma??o sindeposicional, subseq?ente, tornou poss?vel a gera??o de espa?o de acomoda??o suficiente para a preserva??o de dep?sitos fl?vio-lacustres depositados anteriormente e condicionou a prograda??o um sistema de deltas de rios entrela?ados

Made available in DSpace on 2015-03-13T17:08:30Z (GMT). No. of bitstreams: 1 RafaelDS_DISSERT.pdf: 4082190 bytes, checksum: dabe52ff23738bb49110e1bc03f1b41a (MD5) Previous issue date: 2011-02-28 / The structural knowledge of the western portion of the Potiguar Basin is still in its infancy, especially these related to NW-trending fault systems. This paper analyzes the Po?o Verde-Cara?bas Fault System, which was initially recognized in subsurface. The activities involved in this study correspond to remote-sensing analysis and, in particular, to the geometric and kinematic analysis of post-rift sequences of the basin. In addition, the study aimed to determine the stress fields operating in the area. The studies were carried out in an area of 1,000 km?, located in the western portion of Potiguar Basin along the Po?o Verde-Cara?bas Fault System, Rio Grande do Norte State. The remote sensing imagery indicates a predominance of NW-SE-trending lineaments, consistent with the fault system under study, followed by the NE-SW, N-S and E-W directions. The tectonic structures mapped were analyzed only in outcrops of the Janda?ra Formantion. They are joints (filled or not) in all directions, but with predominance of the NW-trending joints. Faults are usually N-S-trending normal faults and NW-SE and NE-SW-trending strike-slip faults. Geodynamic analysis identified two tectonic stress fields: the first field, "Field 1" is represented by an N-S-trending horizontal compression and E-W-trending horizontal extension. This field affected the Potiguar Basin at least until the Miocene. The second field, "Field 2", is represented by an E-W-trending horizontal compression and N-S-trending horizontal extension. This is the present-day stress field and has affected the Potiguar basin since the Pliocene / O conhecimento estrutural da por??o oeste da Bacia Potiguar ainda ? incipiente, principalmente aquele relacionado aos sistemas de falhas NW-SE. Esta disserta??o analisa o Sistema de Falhas Po?o Verde-Cara?bas, onde foi inicialmente individualizado em subsuperf?cie. As atividades realizadas inerentes a este estudo correspondem ? an?lise de sensoriamento remoto e principalmente ? an?lise geom?trica e cinem?tica, da seq??ncia p?s-rifte da bacia. Al?m disso, o estudo teve como objetivo determinar os campos de tens?o que operam na ?rea. Os estudos foram realizados numa ?rea de 1.000 km?, localizada na por??o oeste da Bacia Potiguar, ao longo do Sistema de Falhas Po?o Verde-Cara?bas, estado do Rio Grande do Norte. As imagens de sensoriamento remoto indicam uma predomin?ncia de lineamentos orientados na dire??o NW-SE, consistente com o sistema de falha em estudo, seguido das dire??es NE-SW, N-S e E-W. As estruturas tect?nicas mapeadas foram analisadas somente em afloramentos da Forma??o Janda?ra. Eles s?o juntas (preenchidas ou n?o) em todas as dire??es com predomin?ncia para o trend NW-SE. Falhas normais de dire??o aproximada N-S, falhas transcorrentes nas dire??es NW-SE e NE-SW. A an?lise geodin?mica identificou dois campos de tens?es. O primeiro campo, Campo 1 , ? representado por uma compress?o N-S horizontal e distens?o E-W. Este campo atuou na Bacia Potiguar pelo menos at? o Mioceno. O segundo campo, Campo 2 ? representado por uma compress?o horizontal E-W e distens?o horizontal N-S. Este ? o atual campo de tens?es e tem afetado a Bacia Potiguar desde o Plioceno

Made available in DSpace on 2015-03-13T17:08:37Z (GMT). No. of bitstreams: 1 AndreJPCB_DISSERT.pdf: 4384821 bytes, checksum: f23022c7fe9a0e10cf6b38d62f412fc4 (MD5) Previous issue date: 2013-06-17 / The physical structural modeling tool is being increasingly used in geology to provide information about the evolutionary stages (nucleation, growth) and geometry of geological structures at various scales. During the simulations of extensional tectonics, modeling provides a better understanding of fault geometry and evolution of the tectonic-stratigraphic architecture of rift basins. In this study a sandbox type apparatus was used to study the nucleation and development of basins influenced by previous structures within the basement, variably oriented as regards to the main extensional axis. Two types of experiments were conducted in order to: (i) simulate the individual (independent) development of half-grabens oriented orthogonal or oblique to the extension direction; (ii) simulate the simultaneous development of such half-grabens, orthogonal or oblique to the extension direction. In both cases the same materials (sand mixed with gypsum) were used and the same boundary conditions were maintained. The results were compared with a natural analogue represented by the Rio do Peixe Basin (one of the eocretaceous interior basins of Northeast Brazil). The obtained models allowed to observe the development of segmented border faults with listric geometry, often forming relay ramps, and the development of inner basins faults that affect only the basal strata, like the ones observed in the seismic sections of the natural analogue. The results confirm the importance of basement tectonic heritage in the geometry of rift depocenters / A modelagem estrutural f?sica ? uma ferramenta cada vez mais usada na geologia para fornecer informa??o sobre os diversos est?gios evolutivos (nuclea??o, desenvolvimento) e geometria de estruturas geol?gicas em v?rias escalas. No caso particular da simula??o da tect?nica distensional, a modelagem proporciona uma melhor compreens?o da geometria e evolu??o de falhas e da arquitetura tectonoestratigr?fica de bacias rifte. Neste trabalho foi utilizado um aparato tipo caixa de areia para estudar a nuclea??o e desenvolvimento de bacias influenciadas por estruturas pr?vias no embasamento, com trend vari?vel em rela??o ? dire??o de distens?o. Para tal, foram realizados dois tipos de experimentos para: (i) simular o desenvolvimento individual (independente) de semigr?ben com abertura ortogonal ou obl?qua ? dire??o de distens?o; (ii) simular o desenvolvimento simult?neo desses semigr?ben ortogonais ou obl?quos ? dire??o de distens?o. Em ambos os casos foi utilizado o mesmo material (mistura de areia e gesso) e mantidas as condi??es de contorno. Os resultados obtidos foram comparados com um an?logo natural representado pela Bacia do Rio do Peixe (uma das bacias interiores eocret?ceas do Nordeste do Brasil). Os modelos permitiram observar o desenvolvimento segmentado das falhas de borda, com geometria l?strica, frequentemente formando rampas de revezamento, al?m do desenvolvimento de falhas internas ?s bacias localizadas nas suas por??es mais basais, similares ?quelas observadas nas se??es s?smicas do an?logo natural. Os resultados confirmam a influ?ncia da heran?a tect?nica do embasamento na geometria dos depocentros rifte

Este trabalho trata da caracterização regional entre as drenagens dos rios Paraíba do Sul e Tietê, associada ao processo de captura fluvial, situado entre os municípios de Guararema e Mogi das Cruzes, no Estado de São Paulo. Parte-se da hipótese de processo de captura fluvial no médio curso do Paraíba do Sul e formação do cotovelo de Guararema, o que caracteriza essa anomalia como uma das mais interessantes do planeta Terra. É comum na região o padrão dendrítico e adensamento de drenagens cortados por falhas e fraturas de diversas idades. O embasamento é composto de estruturas cristalinas recobertas por pacotes sedimentares do Terciário e Quaternário. No Graben do Paraíba, superfície alongada e rebaixada entre as Serras do Mar e Mantiqueira, a forte declividade favorece o processo erosivo. A área caracterizada por esses dois importantes rios do território brasileiro é parte integrante do Sistema de Bacias Tafrogênicas do Rift Continental do Sudeste do Brasil (RCSB), a qual foi afetada por falhas NE-SW de grande expressão regional, e o processo de captura seria o responsável pela atual configuração da rede de drenagem. A reativação e movimento de blocos regionais dos períodos Mesozóico e Cenozóico inverteu a direção do Rio Paraíba do Sul em seu setor central, que no passado tributava suas águas no Rio Tietê. Como consequência desse reajustamento regional, alguns dos seus tributários teriam rompido os divisores de água que o separavam das cabeceiras do Tietê e capturado parte de suas drenagens através de processo de recuo de regressivo. O que comprova a captura é a localização do vale seco, feição que pode indicar a antiga ligação entre os dois rios, que foi identificada na área desta pesquisa por meio de análise de cartas, mapas, perfis e fotointerpretação. Devido ao elevado poder erosivo no setor do médio vale do Rio Paraíba, novas capturas podem estar em processo de evolução. / This work deals with the characterization regional drainages between the rivers Tietê and Paraíba do Sul, associated with the capture process river, located between the cities of Guararema and Mogi das Cruzes, State of São Paulo. It starts with the hypothesis capture process in middle course of river Paraíba do Sul and training elbow Guararema what characterizes this anomaly as one of the most interesting of the planet Earth. It is common in the region and the dendritic pattern of drainage densification cut by faults and fractures of various ages. The basement consists of crystalline structures covered by sedimentary packages Tertiary and Quaternary. The Graben Paraíba, elongated surface and lowered between the Serra do Mar and Mantiqueira, the strong declivity favors the erosion process. The area is characterized by these two important rivers of the Brazilian territory is part of the Watershed System Tafrogênicas Continental Rift of Southeastern Brazil (RCSB), which was affected by NE-SW faults of great regional expression, and the capture process would be responsible for the present configuration of the drainage network. The reactivation and movement of regional blocks of Mesozoic and Cenozoic periods inverted the direction of the Paraíba do Sul River in its central section, which in the past taxed waters in Rio Tietê. As a result of this regional readjustment, some of its tributaries have broken the watershed that separated him the headwaters of the Tietê and captured part of its drainage through the process of regressive retreat. This proves the catch is the location of the valley dry feature that may indicate the ancient link between the two rivers, which was identified in this research area through the analysis of charts, maps, profiles and photo interpretation. Due to the high erosive power sector in the middle valley of the River Paraíba, new catch may be in the process of evolution.

Projektet skapades från viljan att framställa en virtuell träningsmiljö där blivande lärare kan öva och bättra på sin icke-verbala kommunikation när dem undervisar. Projektet funkar genom att fånga användarens rörelser och rendera virtuella agenter på en skärm framför användaren. Att stå framför en statisk skärm och undervisa kan dock inte kännas helt realistiskt. Denna rapport kommer gå igenom implementationen av en huvudmonterad display, mer specifikt Oculus Rift, för att skapa en virtuell verklighet och utökningen av de virtuella agenternas beetende och nya sätt att interagera med agenterna. De täcker även resultaten från experimenten där den nya funktionaliteten blev utvärderad. Experimenten gjordes genom att låta 18 personer testa systemet i både den gamla och nya uppsättningen och sedan fylla i frågeformulär efteråt. / This project was created from the desire to provide a virtual training environment for teachers-intraining to practice and improve their non-verbal communication with students. The project worked by capturing the user’s movements and rendering the virtual agent’s to a screen in front of the user. Standing in front of a static screen to hold a lecture might however not feel entirely realistic. This report covers the implementation of a head-mounted display, specifically the Oculus Rift, to create a virtual reality as well as the extension of the virtual agent’s behavior and new ways to interact with the virtual agent’s. It also covers the results of an experiment where the new functionality was evaluated. The experiment was done by allowing 18 persons to test the system in both the old and new configurations and fill in questionnaires afterwards.

La Fièvre de la Vallée du Rift (FVR) est une zoonose observée pour la première fois au Kenya en 1930 qui s'est peu à peu propagée à la plupart des pays d'Afrique. La FVR est une maladie à transmission vectorielle dont le virus appartient au genre Phlebovirus de la famille des Bunyaviridæ. En Afrique de l'Est, l'émergence de foyers est prédite par des modèles statistiques, ce qui n'est pas le cas en Afrique de l'Ouest où les facteurs et les mécanismes en jeu sont encore mal définis. L'objectif de cette thèse est d'identifier les facteurs et les processus épidémiologiques expliquant l'émergence de foyers de FVR au Sénégal, en mettant en œuvre une approche éco-épidémiologique centrée sur les principaux moustiques vecteurs du virus. Par l'étude de variables environnementales et climatiques et par leur exploitation dans des modèles mathématiques, nous avons tenté de répondre à deux questions épidémiologiques majeures : (1) quelles sont les zones potentiellement à risque, et (2) quelles sont les périodes favorables à l'apparition de foyers. L'étude a été menée à l'échelle locale, dans une zone d'environ 10 km2 autour du village de Barkedji situé dans la région sylvo-pastorale du Ferlo.Pour localiser les zones à risque de transmission du virus, nous utilisons la télédétection et l'analyse paysagère afin de caractériser l'environnement favorable aux deux principaux candidats vecteurs du virus, Aedes vexans et Culex poicilipes. Pour identifier les périodes à risque, nous avons développé un modèle d'abondance de populations de moustique des deux espèces vectrices prenant en compte la dynamique des gîtes larvaires (les mares), et dont les simulations ont été validées avec des données de terrain de capture de moustiques. Pour se faire, nous avons dû préalablement développé un modèle dynamique de hauteur d'eau des mares temporaires, modèle calibré et validé à partir de données de terrain et de données d'observation de la Terre.Les résultats de l'analyse paysagère ont confirmé que les milieux favorables aux vecteurs de la maladie pouvaient être caractérisés par télédétection. Ils ont aussi mis en évidence l'importance des mares et de la densité de végétation environnante, et ont abouti à une cartographie de l'hétérogénéité spatiale du risque de circulation de la FVR. Les résultats de l'analyse temporelle ont montré que les années de circulation active du virus coïncidaient avec les années pour lesquelles les deux espèces de moustiques étaient présentes en forte quantité. On observe ainsi deux années à très forte densité des deux moustiques vecteurs, en 1987 et en 2003, correspondant aux années d'épidémie/épizootie les plus importantes dans la région. / The Rift Valley fever (RVF) is an arboviral zoonosis, first identified in Kenya in 1930, which has spread over many African countries. The RVF virus (RVFV) is a mosquito-borne virus member of the family Bunyaviridae, genus Phlebovirus. Statistical models that are used for predicting RVF outbreaks in East Africa do not work in West Africa where the factors and processes involved are still not well described. The aim of this thesis is to identify the factors and epidemiological processes that explain the emergence of RFV outbreaks in Senegal. To achieve that, we have chosen an eco-epidemiological approach targeted on the main candidate mosquito vectors of the RFV virus. By using the environmental and climatic variables and by their exploitation in mathematical models, we tried to answer two major epidemiological questions: (1) where are the potential zones at risk? And, (2) when are the periods favourable to RFV outbreaks?The study has been carried out at a local scale, in an area of about 10 km2 centred on the village of Barkedji in the pastoral Ferlo region in northern Senegal.When identifying risk areas for virus transmission, we used remote sensing and landscape analysis to characterize favourable environments fot the two main candidate vectors, Aedes vexans and Culex poicilipes (Diptera: Culicidae). For predicting risk of RVF outbreaks, we developed a mosquito population model for the two vector species taking into account the dynamics of the ponds as breeding sites. The results of the simulation have been validated with captured mosquito field data. This required the prior development of a temporary pond dynamics model that was calibrated and validated with field and remote sensing data.The results of the landscape analysis confirmed that favourable environments for the mosquito vectors of the RVF could be characterised by remote sensing. The importance of the ponds and the surrounding vegetation density was also highlighted, allowing to map the spatial heterogeneity of RVF circulation risk. The results of the mosquito model simulations showed that years of active virus circulation matched the years when both vector species were densely present. Indeed, the simulations showed high mosquito densities in 1987 and 2003, which correspond to the most important epidemic and epizootic events in that region.

The principal goal of the thesis is to constrain nature of magmatic and alteration processes, character of mantle source(s), geotectonic setting and palaeogeographic implications of the Silurian and Devonian volcanism in Prague Basin (Teplá-Barrandian Unit, Bohemian Massif). The thesis is based on extensive geochemical study covering major- and trace-element geochemistry, neodymium isotope geochemistry and mineral chemistry supported by petrographic and field observations. The most important conclusions of the thesis are as follows: 1. The Silurian volcanic rocks of the Prague Basin represent within-plate, transitional alkali to tholeiitic basalts, which erupted in continental rift setting through thick Cadomian crust. The basalts originated by low degrees of partial melting of garnet peridotite mantle source. Older Wenlock basalts are similar to alkaline ocean island basalts (OIB) derived from subcontinental lithospheric mantle (SCLM), enriched most probably by frozen pods of Ordovician magmas. Younger Ludlow basalts resemble tholeiitic enriched mid-oceanic ridge basalts (EMORB) derived from subduction-modified SCLM depleted by Late Cambrian melting. The Wenlock-Ludlow melting is characterized by contemporaneous mixing of melts derived from both enriched and depleted SCLM mantle domains. 2....

L'autophagie maintient l'homéostasie cellulaire en dégradant les composants cellulaires. Chez l'humain, les protéines LC3 jouent un rôle central dans l'autophagie en interagissant avec d'autres facteurs contenant des régions d'interaction LC3 (LIR). Cette thèse porte sur le rôle de différents facteurs contenant des LIR, tels que le facteur nucléaire DOR et la protéine NSs du virus de la fièvre de la vallée du Rift (VFVR). Les protéines LC3 sont principalement présentes dans le noyau des cellules au repos normales, et leur passage au cytosol en réponse au stress nécessite une interaction avec DOR. Récemment, il a été démontré que cette interaction entre DOR et LC3B dépend de la désacétylation de deux résidus lysine conservés (K49/K51 de LC3A et K46/K48 de GABARAP). Cependant, les détails mécanistiques du rôle des résidus lysine individuels dans le transfert d'autres protéines LC3 demeurent inconnus. De plus, la caractérisation de l'interaction NSs-LC3 ainsi que son impact sur l'autophagie lors de l'infection par le RVFV demeurent évasives. Par conséquent, l'objectif de ces études est d'investiguer les différences structurelles et fonctionnelles des protéines humaines LC3 à différents stades de l'autophagie via leur interaction avec DOR et NSs. Nos études biophysiques et structurales ont permis d’identifier des éléments clés déterminant la spécificité de la région d'interaction LC3 de DOR (DORLIR) pour GABARAP. Nos études structurales ont défini une conformation en feuillet  chez DORLIR lorsqu'elle est en complexe avec GABARAP, ce qui joue un rôle important dans l'établissement de cette spécificité. Les études structurales ont également montré que l'acétylation de la deuxième Lys de GABARAP ou LC3A perturbe des interactions clés du W35 de DORLIR, ce qui conduit à une diminution de l'affinité qui est cohérente avec nos résultats ITC. Ces résultats ont été confirmés grâce à des expériences cellulaires en utilisant des substitutions K-en-Q pour imiter l'acétylation des Lys. En cellules, les substitutions K-en-Q à la deuxième Lys ont entravé le transfert cytoplasmique de GABARAP et de LC3A, ainsi que leur colocalisation avec DOR, tandis que les substitutions K-en-Q à la première Lys se comportent comme des protéines de type sauvage. Dans l'ensemble, la désacétylation de la deuxième Lys conservée est cruciale pour le transfert cytoplasmique de GABARAP et LC3A lors de l'autophagie, ce qui diffère de ce qui a été observé auparavant avec LC3B, où la désacétylation des deux Lys était nécessaire. Cette étude fournit également des informations sur les interactions entre la protéine NSs du VFVR et les protéines LC3, ainsi que l'impact de NSs sur l'autophagie lors de l'infection par le VFVR. Nous avons identifié quatre motifs potentiels d'interaction LC3 (NSs1-4) dans la protéine NSs, et des études d’ITC ont démontré que NSs4 interagit avec une affinité sous micromolaire-micromolaire avec les protéines LC3 humaines. De plus, nous avons confirmé que les protéines LC3 interagissent avec NSs dans les cellules, et que chez les cellules infectées par le RVFV, LC3A colocalise avec NSs. Dans l'ensemble, les résultats indiquent que la protéine NSs joue un rôle clé dans la modification de l'autophagie lors des infections par le VFVR. / Autophagy maintains cellular homeostasis through catabolism of cellular components including organelles, proteins, and pathogens. In humans, the six LC3 (Microtubule-associated protein 1 light chain 3) protein (LC3A, LC3B, LC3C, GABARAP, GABARAPL1 and GABARAPL2) play a pivotal role in autophagy through interactions with other factors that contain LC3-interacting regions (LIRs). This study focuses on the role of different factors that contain LIRs such as the nuclear factor DOR and the NSs protein from the RVFV. LC3 proteins are predominantly present in the nucleus of normal resting cells and their shuttling to the cytosol in response to stress requires interaction with DOR. Recently, this interaction between DOR and LC3B was shown to depend on the deacetylation of two conserved Lys residues (K49/K51in LC3 subfamily proteins and K46/K48 in GABARAP subfamily proteins). However, the mechanistic details of the role of the individual Lys residues in the shuttling other LC3 proteins is unknown. In addition, the characterization of NSs-LC3 interaction as well as its impact on RVFV (Rift Valley fever virus) infection on autophagy remains elusive. Therefore, the goal of these studies is to investigate the structural and the functional differences of the six human LC3 proteins in different stages of autophagy through their interaction with DOR and NSs. Our biophysical and structural studies identified key elements determining the specificity of the LIR from DOR (DORLIR) for the GABARAP subfamily. Our structural studies defined a -sheet conformation in DORLIR when complexed with GABARAP, which is important role for establishing this specificity. ITC studies with acetylated versions of LC3A and GABARAP demonstrated that acetylation of the second Lys significantly decreases binding to the DORLIR whereas acetylation at the first Lys has little to no effect. Our structural studies also demonstrate that acetylation at the second Lys of either GABARAP or LC3A disrupts key interactions between W35 of the DORLIR, which leads to the decreased affinity. The in vitro results were verified in cellular experiments using K-to-Q substitutions to mimic Lys acetylation. In cells, K-to-Q substitutions at the second Lys impaired the cytoplasmic shuttling of both GABARAP and LC3A from the nucleus as well as their colocalization with DOR, whereas K-to-Q substitutions at the first Lys behaved like wild-type proteins. Taken together, the deacetylation of the second conserved Lys is critical for the cytoplasmic shuttling of GABARAP and LC3A during autophagy, which is in contrast to what was observed with LC3B where deacetylation of both Lys was required. This study also provides insights into interactions between the NSs protein of RVFV and LC3 proteins and the impact of NSs on autophagy during RVFV infection. We identified four potential LIR motifs (NSs1-4) in the NSs protein and ITC studies demonstrated that NSs4 interacts with submicromolar-micromolar affinity with the human LC3 proteins. In addition, we confirmed that LC3 proteins interact with NSs in cells and that in RVFV infected cell LC3A colocalizes with NSs. Taken together, the results indicate that the NSs protein plays a key role in altering autophagy during RVFV infections.

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