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ANBALAGAN, SAVANI. « Role of saccharomyces cerevisiae Rif1 and Rif2 proteins in protection of telomeres ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/43717.
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Eukaryotic cells distinguish their chromosome ends from accidental DNA double-strand breaks (DSBs) by packaging them into protective structures called telomeres that prevent DNA repair/recombination activities. In this work, we investigated the role of key telomeric proteins in protecting Saccharomyces cerevisiae telomeres from degradation. We show that the shelterin-like proteins Rif1, Rif2, and Rap1 inhibit nucleolytic processing at both de novo and native telomeres during G1 and G2 cell cycle phases, with Rif2 and Rap1 showing the strongest effects. Also Yku prevents telomere resection in G1, independently of its role in non-homologous end joining. Yku and the shelterin-like proteins have additive effects in inhibiting DNA degradation at G1 de novo telomeres. In particular, while Yku plays the major role in preventing initiation, Rif2 and Rap1 act primarily by limiting extensive resection. Finally, Rap1 and Rif2 prevent telomere degradation by inhibiting MRX access to telomeres, which are also protected from the Exo1 nuclease by Yku. Thus, chromosome end degradation is controlled by telomeric proteins that specifically inhibit the action of different nucleases.
Since Rif1 plays a very minor role in protecting wild type telomeres from degradation, we further investigated whether Rif1 participates in telomere protection in combination with other capping activities, like those exerted by the CST complex (Cdc13-Stn1-Ten1). We found that, unlike RIF2 deletion, the lack of RIF1 is lethal for stn1ΔC cells and causes a dramatic reduction in viability of cdc13-1 and cdc13-5 mutants. Both cdc13-1 rif1Δ and cdc13-5 rif1Δ cells display very high amounts of telomeric single-stranded DNA and DNA damage checkpoint activation, indicating that severe defects in telomere integrity cause their loss of viability. In agreement with this hypothesis, lethality in cdc13 rif1Δ cells is partially counteracted by the lack of the Exo1 nuclease, which is involved in telomeric single-stranded DNA generation. Like CDC13, RIF1 also genetically interacts with the Polα-primase complex, which is involved in the fill-in of the telomeric complementary strand. Thus, these data highlight a novel role for Rif1 in assisting the essential telomere protection function of the CST complex.
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MARTINA, MARINA. « Roles of shelterin-like proteins and yku in saccharomyces cerevisiae telomere homeostasis ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41884.
Texte intégralRésumé :
Telomeres are specialized nucleoprotein complexes that distinguish the natural ends of linear chromosomes from intrachromosomal double-strand breaks. In fact, telomeres are protected from DNA damage checkpoints, homologous recombination or end-to-end fusions that normally promote repair of intrachromosomal DNA breaks. When chromosome end protection fails, dysfunctional telomeres are targeted by the DNA repair and recombination apparatus, whose outcomes range from the generation of chromosomal abnormalities, general hallmarks for human cancer cells, to permanent cell cycle arrest and cell death. While several studies address the consequences of telomere dysfunctions, the mechanisms by which telomere protection is achieved remain to be determined. During my PhD, I contributed to investigate this issue by analyzing the role of evolutionarily conserved telomeric proteins in protecting budding yeast telomeres from degradation.
In particular, the data obtained during the first year of my PhD show that the shelterin-like proteins Rif1, Rif2, and Rap1 inhibit nucleolytic processing at both de novo and native telomeres during G1 and G2 cell cycle phases, with Rif2 and Rap1 showing the strongest effects. Also the Yku complex prevents telomere resection in G1, independently of its role in non-homologous end joining. Yku and the shelterin-like proteins have additive effects in inhibiting DNA degradation at G1 de novo telomeres. In fact, while Yku plays the major role in preventing initiation, Rif2 and Rap1 act primarily by limiting extensive resection. In particular, Rap1 and Rif2 prevent telomere degradation by inhibiting MRX (Mre11-Rad50-Xrs2) access to telomeres, which are also protected from the Exo1 nuclease by Yku.
The MRX complex is also necessary to maintain telomere length by recruiting the Tel1 kinase, and Rif2 was recently shown to interact with the C-terminus of Xrs2. As also Tel1 binds the same portion of Xrs2, it has been proposed that Rif2 and Tel1 might compete with each other for binding to MRX, with Rif2 preventing Xrs2 interaction with Tel1. This issue was explored during the second part of my PhD by taking advantage of the TEL1-hy909 mutant allele, previously identified as a dominant suppressor of the hypersensitivity to genotoxic agents and checkpoint defects of Mec1-deficient cells (Baldo et al., 2008). The data obtained by this analysis provide evidence that regulation of telomere processing and elongation relies on a balance between Tel1 and Rif2 activities. In particular, Tel1 appears to regulate telomere nucleolytic processing by promoting MRX activity. In fact, the lack of Tel1 impairs MRX-dependent telomere resection, which is instead enhanced by the Tel1-hy909 mutant variant. Our data indicate that the Tel1-hy909 variant is more robustly associated than wild-type Tel1 to double-strand-break (DSB) ends carrying telomeric repeat sequences. Furthermore, it increases the persistence of both the MRX complex and the telomerase subunit Est1 at a DSB adjacent to telomeric repeats, which in turn likely account for the increased telomere resection and elongation in TEL1-hy909 cells. Strikingly, Rif2 is unable to negatively regulate processing and lengthening at TEL1-hy909 telomeres, indicating that the Tel1-hy909 variant overcomes the inhibitory activity exerted by Rif2 on MRX. Altogether, these findings highlight a primary role of Tel1 in overcoming Rif2-dependent negative regulation of MRX activity in telomere resection and elongation.
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Engels, Silke. « Sugars in early and late polyketide biosynthesis functional studies of rifL, rifK and rifM in rifamycin biosynthesis ; towards the characterisation of a PKS gene cluster from Streptomyces sp. GW2/5831, encoding the biosynthesis of the polycyclic xanthone IB-00208 ». München Verl. Dr. Hut, 2009. http://d-nb.info/999629123/04.
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Flynn, Luke. « Rift ». Digital Commons @ Butler University, 2015. http://digitalcommons.butler.edu/grtheses/268.
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Cornwell, David Graham. « Magma-assisted continental rift margins : the Ethiopian rift ». Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30462.
Texte intégralRésumé :
Continental rifting and incipient seafloor spreading are observed either side of the main Ethiopian rift (MER). EAGLE (the Ethiopia Afar Geoscientific Lithospheric Experiment) included a 400 km-long profile containing 97 passive seismometers to investigate the change from mechanical to magmatic extension by defining the lithospheric structure and extent of magmatism beneath the rifted northern MER. Changes in crustal structure along the cross-rift profile are imaged using forward modelling, H-kappa stacking and non-linear inversion analyses of receiver functions. The lithospheric structure is inherently different beneath the north-western rift flank, rift valley and south-eastern rift flank, with contrasting crustal thickness and composition, upper mantle velocity and lithospheric anisotropy. Magmatic addition is imaged in the form of an 6--18 km-thick underplate lens at the base of the crust beneath the high Ethiopian plateau and zones of intense dyking and partial melt beneath the rift valley. The underplate layer probably formed synchronous with an Oligocene flood basalt event and therefore pre-dates the rifting by ~20 Myr. A 20--30 km-wide magmatic system pervades the entire crust beneath volcanic chains that mark the locus of current rift extension. To the southeast of the rift, a lithospheric suture is inferred, which was created during the Precambrian collision of East and West Gondwana. Collision-related lithospheric fabric is proposed to be the main source of strong anisotropy observed along the entire profile, which is locally augmented by rift-related magmatism. An active followed by passive magma-assisted rifting model that is controlled by a combination of far-field plate stresses, pre-existing lithospheric framework and magmatism is preferred to explain the evolution of the northern MER.
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Arnautov, O. I. « Oculus Rift ». Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/44891.
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Nowadays our world is closely connected with technologies. Changes come in people's lives with technology. People invent new gadgets, tools, machines and more useful things every day. As a rule, all these inventions make our life better and easier.
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Liebrenz, Boris. « Die Rifā‛īya ». Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-202876.
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Dávila, Federico Carlos Eduardo. « Turismo como contribución al desarrollo regional sustentable en Venezuela caso de estudio : Municipio Andrés Bello y Parroquia Jají, Mérida/Venezuela ». Rottenburg am Neckar Kersting, 2005. http://www.kersting-verlag.com/riff/titles/riff05/.
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Jackson, Christopher Aiden-Lee. « Structural and stratigraphic evolution of rift basins : the Hammam Faraun area, Suez rift, Egypt ». Thesis, University of Manchester, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488323.
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This project aims to integrate structural and stratigraphic data from the Hammam Faraun area, Suez rift, Egypt, to investigate the temporal and spatial evolution of normal fault zones, fault arrays and fault-related folds in extensional settings, and the control the evolving structural style has on syn-rift depositional patterns and sequence stratigraphy. Structural and stratigraphic data from across the Hammam Faraun fault block suggests that during the early stages of rifting deformation was distributed across the fault block on numerous short (1-4 km), low displacement (<1 km) fault segments. These either grew and linked to form longer fault zones, or became inactive during the initial c. 6-7 Myr of rifting. During this phase, the majority of deformation was accommodated by the intrablock fault zones, which were surface-breaking and had greater displacement than those that became the rift border faults, which were blind at this time. Detailed analysis of the Hammam Faraun fault zone (HFFZ) suggests that at-surface monoclinal growth folding characterised the initial stages of fault growth, with secondary normal faulting and layerparallel slip accommodating distributed deformation in the cover. These observations are consistent with analogue and kinematic models based on trishear. Integration of structural (e. g. fault and fold relationships) and displacement-length (D-L) characteristics with detailed stratigraphic data (e. g. thickness and facies variations, onlap patterns) indicates that the during the initial c. 2.4 Myr of rifting, the intra-block East Tanka fault zone (ETFZ) was initially composed of two isolated segments c. 1-1.5 km long, separated by a transverse hangingwall high. Subsequent stratigraphic patterns indicate that > c. 2.4 Myr after the initiation of rifting, the two isolated fault segments hard-linked to form a longer fault zone, and the locus of maximum displacement and subsidence migrated into the region of linkage. The shift in the locus of activity is consistent with conceptual models of fault growth by segment linkage. Subsurface analysis of the shallow part of the October fault zone (OFZ), offshore central Suez rift, suggests both simple radial propagation, and growth and linkage of initially isolated segments were important in its evolution. Stratigraphic patterns in growth strata adjacent to the fault zone suggest that faulting initiated in the lower Pliocene, and overall the fault zone propagated southwards through time. The relationship between shallow fault zone, and the deepseated, basement-involved fault zone suggests that the underlying fault zone controlled the temporal and spatial evolution of the fault zone. Changes in basin geometry and subsidence patterns, linked to the evolution of fault zones, fault arrays and associated fault-related folds, had a marked control on syn-rift depositional patterns and sequence stratigraphy. For example, growth and hard-linkage of the ETFZ influenced syn-rift sediment supply pathways and facies distributions in early syn-rift continental deposits. Overlying tidal deposits are composed of recurring TST and HST deposits that are interpreted to reflect the continuous creation of accommodation in the hangingwall to the fault zone. Finally, shallow marine deposits show marked variations in stratal stacking patterns and key stratal surface development that can be related to the evolving basin-bounding fault zone. The key generic observations from the outcrop and subsurface studies are: i) rift basin structural style during the early stages of rifting is markedly different to that encountered in the latter stages of rifting, ii) the growth of normal fault zones by segment linkage is an important process in the evolution of basin-bounding fault zones in rifts, iii) the temporal evolution of normal fault zones can only be determined by integrating detailed stratigraphic data with structural observations, iv) folding is an important element in the evolution of normal fault zones in extensional settings, v) syn-rift depositional patterns and the sequence stratigraphic evolution of rifts is strongly influenced by the evolution of fault zones and fault arrays.
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Flotté, Nicolas. « Caractérisation structurale et cinématique d'un rift sur détachement : le rift de Corinthe-Patras, Grèce ». Paris 11, 2003. http://www.theses.fr/2003PA112132.
Texte intégralRésumé :
Une étude structurale de la marge sud du rift de Corinthe montre l'existence d'un détachement quaternaire qui traverse le nord du Péloponnèse du golfe Saronique au golfe de Patras, sur plus de 150km. Sa partie à terre est aujourd'hui inactive, avec un pendage actuel à l'émergence de 30-35ʿN et s'aplatissant vers le nord jusqu'à 0-10ʿN puis augmentant progressivement de pendage sous le golfe. D'autres failles normales, à plus fort pendage nord, affectent le toit du détachement et se sont progressivement branchées dessus. La restauration en profondeur suggère qu'il se prolonge sous le golfe dans la zone d'activité sismique à faible pendage vers le nord mise en évidence par les études sismologiques. Les failles actives de Psathopyrgos, Aigion et Héliké sont celles qui transfèrent actuellement en surface le jeu du détachement. L'émergence du détachement s'est initiée d'E en W il y a 1,7-1Ma et est scellée depuis environ 900ka. La déformation a ensuite progressivement migré vers le nord sur des systèmes de failles qui restent actifs durant une période de 250-400ka. Au niveau du golfe de Patras, les données de sismologie montrent que l'émergence du détachement est toujours active. Cette évolution différentielle des deux systèmes est accommodée des failles de transfert responsables du décalage de 25km entre les deux golfes. L'étude des calcites de failles montre que les brèches tectoniques sont cimentées par deux générations de calcites. La première s'est formée à partir d'une eau de formation à une profondeur supérieure à 1200m et la deuxième à partir d'une eau météorique à une profondeur de 500-1000m. Ces données permettent d'estimer un taux de surrection de 1,7-2,5mm/a comparable à celui déterminé sur la côte (e. G. Stiros, 1998). La datation de ces calcites par la méthode U/Th confirme l'âge récent du rift. Malgré de grandes incertitudes, les résultats obtenus valident l'application de cette méthode de datation dans des systèmes faillés quaternaires en milieu carbonatésA structural study of the southern margin of the Corinth rift shows the existence of a quaternary detachment fault, which outcrops along 150km in the northern Peloponnese, from the Saronic gulf to the Patras gulf. Its onshore part is inactive. It dips 30-35ʿN, flats northward till 0-10ʿN and progressively increases beneath the gulf. Steeper normal faults cut through the hangingwall of the detachment and progressively branched onto it. Balanced cross-sections suggest that the onshore detachment prolonged beneath the gulf in the low-angle seismological zone. Since 300ky, the Psathopyrgos, Helike and Aigion active faults transfer the slip from the detachment to the surface. The emergence of the detachment initiated from east to west 1. 7-1My ago, and is sealed since roughly 900ky. The strain has progressively migrated toward the north on several fault-system which remained active during 250-400ky. In the gulf of Patras, seismological data show that the emergence of the detachment is still active. This differential evolution is accommodated by transfer-faults and led to the 25km shift of the Patras and Corinth gulfs. A study of fault-crystallisations shows that syntectonic breccias are cemented by two generations of calcite. The first was formed with formation water at a depth of more than 1200m and the second generation was formed with meteoric-water at a depth of 500-1000m. These data allow determining an uplift rate of 1. 7-2. 5mm/y. This result is close to uplift rates determined near the coast. Dating of these calcites by the U/Th method confirms the young age of the Corinth-Patras rift. The results show that this method is a reliable way for quaternary faults
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Jones, Joshua Robert. « Investigating volcano tectonic interactions in the Natron Rift of the East African Rift System ». Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103780.
Texte intégralRésumé :
Continental rifting, like other plate tectonic processes, plays a large role in shaping the Earth's crust. Active rift zones evolve from repeated tectonic and magmatic events including volcanic activity. Through investigations of currently and previously active rifts, scientists have discovered considerable interactions between these tectonic and magmatic processes during a rift's evolution; however questions remain about these interactions especially in youthful stages of rifts. We investigate an early phase magma-rich section of the East African Rift System (EARS), named the Eastern Branch to assess volcano-tectonic interactions. The Eastern Branch of the EARS consists of volcanically rich rifts that are actively spreading the Nubian Plate, Somalian plates, and Victoria block at different evolutionary stages making it an ideal study area for volcano-tectonic interactions. Our initial investigation of active volcano-tectonic interactions centered on a rifting event that occurred between 2007-2008 in the Natron Rift, a rift segment in the southern Eastern Branch located in Northern Tanzania. This rifting event contained multiple occurrences of tectonic, magmatic, and volcanic activity in close proximity. We examine the stress transferred from these events to the Natron Fault, which is the major border fault in the area, with analytical modeling using the USGS program Coulomb 3.4. We processed Global Positioning System (GPS) data that recorded slip on the major border fault in the region in early January 2008 and test which events could generate large enough stress changes to trigger the observed slip using a previously defined threshold of 0.1 MPa. These initial models were created using simplified
model parameters, such as an elastic homogeneous half-space, and find that 1) magmatically induced stress perturbations have the potential to trigger fault slip on rift border faults, 2) magmatic events have the potential to trigger strike‐slip motions on a rift border fault, and 3) the proximity of magmatic activity may affect occurrences of slip on adjacent border faults. We then further investigate volcano-tectonic interactions in the Natron Rift by testing using numerical modeling with the CIG finite element code PyLith. We systematically test how adding topography, heterogeneous materials, and various reservoir volumes to a deflating 3 km deep magma reservoir system at the active volcano Ol Doinyo Lengai can affect stress transfer to the adjacent Natron Fault. We compare eight models with variations in topography, material properties, and reservoir volumes to calculate the percent differences between the models; to test their effects on the stress change results. We find that topography plays the largest role with the effect increasing with reservoir size. Finally, we seek to improve the capability of investigating volcano-tectonic interactions in the Natron Rift at faster time- scales by improving Global Navigation Satellite System (GNSS) positioning data (latitude, longitude, and height) collection and distribution capabilities. In the final part of this work, we describe a new Python-based data broker application, GNSS2CHORDS, that can stream real-time centimeter precision displacement data distributed by UNAVCO real-time GNSS data services to an online EarthCube cybertool called CHORDS. GNSS2CHORDS is applied to the TZVOLCANO GNSS network that monitors Ol Doinyo Lengai in the Natron Rift and its interactions with the adjacent rift border fault, the Natron Fault. This new tool provides a mechanism for assessing volcano-tectonic interactions in real-time. In summary, this work provides a new avenue for understanding volcano-tectonic interactions at unprecedented, 1-second time-scales, demonstrates slip can be triggered by small stress changes from magmatic events during early phase rifting, and provides insights into the key role of volcanic topography during volcano-tectonic interactions.Doctor of Philosophy
Investigating interactions between active volcanoes and tectonics (fault zones) is important for understanding how continental rifts grow and evolve over time. Modern researchers use geodetic data, geologic models, and computer simulations of rift processes; like volcanic eruptions and fault movement; to understand how stress in transferred and material deforms due to rift activity. We are especially interested in understanding the stress interactions when volcanic eruptions and earthquakes happen together over a short time period. Our projects apply these tools to examine a segment of the largest active continental rift zone, the Natron Rift in the East African Rift System (EARS), to understand more about the details of these volcano-tectonic interactions when continents break apart (rifting). We first present results that stress transferred to the Natron Fault associated with magmatic activity from the volcano Ol Doinyo Lengai may trigger a major fault to move. Next, we continue our investigations into volcano-tectonic interactions by seeing how volcanic properties could affect stress transferred in the Natron Rift region. We choose to initially test stress variations associated with different 1) topography surfaces, 2) material properties, and 3) reservoir volumes associated with the volcano Ol Doinyo Lengai using a more advanced computer modeling approach. This deeper investigation provides information about the individual roles these parameters play in a younger rift region. We present results that topography has the most influence on the stress transferred to the Natron Fault in our models, and that the other parameters did not play a large role in influencing the stress transferred. Finally we work to increase the ability for researchers to perform geodetic studies in the Natron Rift by providing a new method to share surface displacement data at an unprecedented 1 position a second rate (near real-time). This new method is a data broker application called GNSS2CHORDS that can stream cm precision displacement data to an online cybertool called CHORDS. With our models and data provided through open source methods this work contributes significantly to our understanding of volcano-tectonic interactions.
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Niemelä, Jimmy. « Impostor Rendering with Oculus Rift ». Thesis, KTH, Data- och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156881.
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This report studies impostor rendering for use with the virtual reality head mounted display Oculus Rift. The technique is replacing 3D models with 2D versions to speed up rendering, in a 3D engine. It documents the process of developing a prototype in C++ and DirectX11 and the required research needed to complete the assignment. Included in this report are also the steps involved in getting Oculus Rift support to work in a custom 3D engine and measuring the impact of impostor rendering when rendering to two screens of the head mounted display. The goal was to find the maximum models the engine could draw, while keeping the frame rate locked at 60 frames per second. 2 testers at Nordicstation came to the conclusion that 40-50 meters was the optimal distance for impostor rendering. Any closer and the flatness was noticeable. The results showed a clear improvement in frame rate when rendering a graphically intensive scene. The end result showed that the goal could be achieved at a maximum of 3000 trees with 1000 leaves. Impostor rendering was deemed effective when drawing beyond 500 trees at a time. Less than that and the technique was not needed to achieve 60 frames per second.Denna rapport undersöker renderingstekniken impostors när den används i en simpel 3D motor tillsammans med virtuella verklighetshjälmen Oculus Rift. Impostors betyder på engelska bedragare och tekniken går ut på att den byter ut avancerade 3D modeller mot simpla 2D versioner när de är ett visst avstånd ifrån användarens virtuella kamera. Om den är korrekt implementerad ska användaren inte märka att vissa modeller är platta och tekniken sparar på resurser då grafikmotorn inte behöver rita ut alla modeller. Rapporten går igenom vad som undersöktes i förundersökningen för att kunna utveckla en prototyp med utvecklingspråket C++ och DirectX 11. I rapporten står även hur prototypen utvecklades och hur stöd för Oculus Rift lades till. De slutliga resultaten visade att impostors hade en stor påverkan på uppdateringshastigheten när antalet 3D modeller som skulle ritas var många, annars hade tekniken ingen påverkan för att nå 60 bilder per sekund. 2 testare från Nordicstation kom fram till att ett avstånd på 40-50 meter från spelarens kamera till utritning av impostors var lämplig, för att dölja att de endast är platta versioner av 3d modeller. Testet visade att motorn kunde rita ut 3000 träd, med 1000 löv på varje, och hålla 60 bilder per sekund, vilket var målet. Detta på ett avstånd av 40m på impostors. Impostorrendering var effektiv när man ritade ut fler än 500 träd åt gången. Mindre antal gav ingen märkbar effekt på testdatorn som användes för testet.
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Garvin, Andrew Paul. « The rift in the daguerreotype ». Thesis, Lancaster University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322844.
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Kedziora, Sylwia Maria. « How Rif1 controls telomere length ». Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=235993.
Texte intégralRésumé :
The activation of replication origins is temporally regulated in S phase, with some origins activating early and some late. The molecular events controlling the temporal programme are not well understood, but in S. cerevisiae there is a close relationship between telomere length and nearby origin activation time. In the first part of this thesis I explore how the initiation time of origins near to telomeres is regulated by telomere length in a manner dependent on the Tel1 kinase. I demonstrate that an induced short telomere drives early activation of a nearby origin, but that in the absence of Tel1 the same origin activates late. In the second, major part of this thesis I focus on how the Rif1 protein negatively regulates length of the terminal TG1-3 repeats. While Rif1 has long been known to control telomere length, the mechanism through which Rif1 prevents telomere over-extension has remained unclear. Recently Rif1 was discovered to act in DNA replication control as a Protein Phosphatase 1-targeting subunit, directing Protein Phosphatase 1 (PP1) to dephosphorylate the MCM replicative helicase complex. I therefore investigated whether Rif1 also controls telomere length through PP1 interaction. I examine the effects of a mutant Rif1 with its PP1 interaction sites mutated to ablate PP1 binding. I found the mutant Rif1 binds normally to telomeres but causes a long telomere phenotype, similar to that in ∆rif1 cells, implicating Rif1-PP1 interaction in telomere length control. In further experiments I show that tethered PP1 can partially substitute for Rif1 in telomere length control. I also establish that the effect of Rif1-PP1 on telomere length does not operate indirectly through replication timing control, but rather appears to act through a direct pathway controlling telomerase recruitment. I discuss potential dephosphorylation targets, and the mechanism through which Rif1 and PP1 may control telomere length homeostasis. To summarise, my PhD research demonstrates that S. cerevisiae Rif1 acts with PP1 to repress telomerase-mediated TG1-3 repeat extension.
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Ferrer, Bustamante Claudia Mariela, Llanos Víctor Hugo Ibarra et Flores Carlos Rafael Prialé. « Plataforma virtual de Rifa Yolo ». Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/625450.
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El presente proyecto de negocio ha sido trabajado con la finalidad de atender la necesidad de las personas que son usuarias del comercio electrónico ofreciéndoles una manera innovadora de obtener productos por un costo mínimo.
El objetivo de este plan es aproximar productos a los consumidores que tienen el deseo de tenerlos pero que por diversas razones no han podido conseguirlos.
En esta propuesta elaborada para cumplir el deseo de nuestro cliente elegido, se ha trabajado en la identificación de sus principales motivaciones al momento de comprar por internet como son: el ahorro de tiempo, la conveniencia y la búsqueda del mejor precio, lo cual se contrastó con los principales problemas que enfrentan al momento de hacer compras en un espacio físico: prolongada espera para ser atendido y pagar, precios altos de los productos y mala atención. Además, se logró evidenciar sus temores respecto a la experiencia de comprar por internet.
El proyecto de negocio plantea el servicio de sortear productos de marcas reconocidas por nuestro cliente por lo cual se pondrá a la venta boletos de rifas durante un tiempo establecido para cada sorteo, esto se realizará a través de una plataforma virtual ágil y confiable donde el cliente podrá comprar cuantas opciones desee para ganar. Nuestra propuesta de valor propone el envío del producto libre de costo, transmisiones en vivo y notificaciones de todos los sorteos que serán debidamente validados, variedad de productos, garantía, medios de pago sencillos, bonificaciones.This business project has been developed with the purpose of meeting the needs of people who are users of electronic commerce by offering an innovative way to obtain products for a minimal cost. The objective of this plan is to bring products closer to consumers who have the desire to have them but for various reasons have not been able to get them. In this proposal developed to fulfill the desire of our chosen client, we have worked on identifying their main motivations when buying online such as: saving time, convenience and searching for the best price, which was contrasted with the main problems they face when making purchases in a physical space: prolonged waiting to be attended and paid, high prices of products and poor attention. In addition, it was possible to highlight their fears regarding the experience of shopping online. The business project raises the service of raffling products of brands recognized by our client, for which raffle tickets will be sold for a set time for each draw, this will be done through an agile and reliable virtual platform where the customer can buy as many options as he wants in order to win the raffle. Our value proposition proposes sending the product free of cost, live broadcasts and notifications of all the draws that will be duly validated, variety of products, guarantee, simple means of payment, bonuses.
Trabajo de investigación
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Rarity, Gil. « Digital outcrop characterisation of syn-rift structure and stratigraphy : Nukhul half-graben, Suez Rift, Egypt ». Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/digital-outcrop-characterisation-of-synrift-structure-and-stratigraphy-nukhul-halfgraben-suez-rift-egypt(6969e8ae-4039-4d36-861b-de4496492488).html.
Texte intégralRésumé :
Syn-rift exposures are a prime source of knowledge on the structure and stratigraphy of rift basins and are vital for the petroleum industry as analogues for subsurface reservoirs. Focusing on superb exposures of the Oligo-Miocene rift initiation Nukhul half-graben in the Suez Rift, Egypt, this study investigates applications of 3D digital survey techniques, particularly terrestrial light detection and ranging (lidar), for (i) the analysis of syn-rift fault and facies architecture, and (ii) the building and testing of outcrop-based reservoir analogue models for early syn-rift settings. Lidar-based digital outcrop mapping of the Nukhul half-graben, combined with conventional fieldwork, facilitated quantification of thickness and facies relationships within syn-rift strata, and variations of throw along normal faults. The results provide new insights into the tectono-sedimentary evolution of the intra-block half-graben. At rift initiation, regional/eustatic sea-level and antecedent drainage are interpreted as the dominant controls on accommodation development and deposition, respectively. However, after just c. 2.5 myr of rifting, the structural template imposed by the propagation and linkage of four initially isolated pre-cursor segments of the Nukhul Fault became the dominant control on accommodation development and basin physiography. Progressive SE-NW back-stepping of facies strike-parallel to the Nukhul Fault suggests hangingwall subsidence was locally sufficient to outpace falls in regional sea-level, resulting in a dynamic transgressive system that progressed from a restricted tidal embayment to shallow marine seaway along fault strike. After c. 4.3 myr of rifting, regional drowning of the tidal system provides evidence for progressive localisation of displacement onto the present-day block-bounding structures and declining activity on the intra-block Nukhul Fault during the transition from rift initiation to rift climax. Development of digital outcrop techniques such as point cloud facies classification, 3D deterministic channel modelling and net-to-gross analysis provided reliable geostatistics on the geometry, distribution and heterogeneity of tide-influenced facies of the syn-rift Nukhul Formation. The high volume, reliability and spatial coverage of data reduced uncertainties related to stochastic facies modelling (in this case sequential indicator simulation and object-based techniques), facilitating building and testing of high-resolution analogue models for the complex facies and sequence architecture of early syn-rift tidal reservoirs. Visual analysis of static reservoir connectivity suggests some of the smallest-scale depositional elements, i.e. thin intercalations of mudstone and sandstone lamina in heterolithic facies, have the biggest impact on both reservoir volume and vertical connectivity in this syn-rift tidal system. Heterogeneities at the sequence stratigraphic scale also have significant impact on vertical reservoir compartmentalisation, whereas tidal channel lag deposits and tidal mud drapes have more localised effects. Use of lidar, when combined with conventional fieldwork, offers a powerful tool for quantitative spatial analysis of fault and facies architecture, tightly constraining 3D structural and stratigraphic interpretations and effectively increasing the statistical significance of outcrop analogues for reservoir characterisation. Future developments in survey technologies alongside geoscience-specific software for the integration and analysis of outcrop datasets will provide more diverse and quantitative information on geological heterogeneity, and promote wider-ranging applications in Earth sciences.
17
Blocher, William Burke. « Fault Geometry and Kinematics within the Terror Rift, Antarctica ». The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1510176632279205.
Texte intégral
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Shen, Jiasi. « RIFL : a language with filtered iterators ». Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101587.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 143-146).
RIFL is a new programming language that enables developers to write only common-case code to robustly process structured inputs. RIFL eliminates the need to manually handle errors with a new control structure, filtered iterators. A filtered iterator treats inputs as collections of input units, iterates over the units, uses the program itself to filter out unanticipated units, and atomically updates program state for each unit. Filtered iterators can greatly simplify the development of robust programs. We formally define filtered iterators in RIFL. The semantics of filtered iterators ensure that each input unit affects program execution atomically. Our benchmarks show that using filtered iterators reduces an average of 41.7% lines of code, or 58.5% conditional clauses and 33.4% unconditional computation, from fully manual implementations.
by Jiasi Shen.
S.M.
19
Bell, Rebecca E. « Tectonic evolution of the Corinth Rift ». Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63290/.
Texte intégralRésumé :
The evolution of extensional processes at continental rift zones provides important constraints on the underlying lithospheric deformation mechanisms, level of seismic hazard and location of likely hydrocarbon traps. The Corinth rift in central Greece is one of the few examples that has experienced a short extensional history (< 5 Myr), has a relatively well–known pre–rift structure, is experiencing pure extension, and is located in a fluctuating marine–lacustrine setting producing characteristic cyclical stratigraphy. Traditionally, the rift has been described as an asymmetric half–graben controlled by N–dipping faults on the southern margin. This view has been challenged by increasing seismic data from the off-shore part of the rift which show it is more complex, analogous to more developed rifts like the East African rift and Red Sea. High resolution and deep penetration seismic reflection data across the entire offshore rift zone are combined with onshore geomorphological data to constrain: the architecture of major rift–bounding faults; basin structure; spatial and temporal evolution of depocentres; total extension across the rift; and slip rates of major faults from stratigraphic analysis and dislocation modelling of long term deformation. Stratigraphy within the offshore Corinth rift is composed of a non reflective older unit (oldest syn–rift sediments are ca. 1–2 Ma) and a well stratified younger unit separated by a ca. 0.4 Ma unconformity. Net basement depth is greatest in the present centre of the rift zone (2.7–3 km) and decreases to the east and west (1.5–1.6 km). The 0.4 Ma unconformity surface records an important change in rift geometry. Pre. 0.4 Ma, sediment deposition occurred in 20–50 km long isolated basins, controlled by both N and S–dipping faults. Post 0.4 Ma, sediment deposition and basement subsidence has been enhanced in areas between these originally isolated basins creating a single 80 km long central depocentre. Since 0.4 Ma activity has became focused on mostly N–dipping faults. However, in the west, N tilting stratigraphy and basement indicate S–dipping faults are locally structurally dominant. Late Quaternary averaged major fault slip rates are 3–6 mm/yr on the N-dipping south margin faults, >1.8 mm/yr on S–dipping offshore faults, and 1–3 mm/yr on faults in the eastern rift. Total extension over rift history (Late Pliocene to present) has been greatest in the west (8 km), with extension distributed over many faults (most now inactive) spaced at 5 km intervals. To the east total extension is reduced (5–6 km) and is distributed over fewer faults spaced at 15–35 km intervals. There are large differences in rift character along the rift axis and throughout rift history. The highest geodetic rates over the last 10–100 years are in the western part of the rift and do not correspond to the area of greatest offshore basement depth. This suggests a recent change in the locus of strain focusing, potentially analogous to the change that occurred in rift geometry ca. 0.4 Ma.
20
Yousupova, M. F. « Oculus rift-change the gaming forever ». Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40513.
Texte intégralRésumé :
The creator of one of the most talked-about VR goggles is a
young virtual-reality enthusiast Palmer Luckey. His passion about
games and dream to play video games in simulated 3D-worlds
helped him to become the owner of one of the largest collections of
head-mounted displays in the world in search of the experience of
actually being in the game. However, there was nothing to bring the
experience from dreams to reality. Luckey set up to change it.
21
Petri, Benoît. « Formation et exhumation des granulites permiennes : établir les conditions pré-rift et déterminer l'histoire d'exhumation syn-rift ». Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAH012/document.
Texte intégralRésumé :
Cette étude a visé à contraindre les processus tectoniques, magmatiques et métamorphiques actifs dans la croûte moyenne, du Permien à l’exhumation des roches pendant les riftings mésozoïques, en se focalisant sur un gabbro permien dans les nappes austroalpines (Italie du nord, sud-est de la Suisse). L’évolution du gabbro de Sondalo, mis en place dans l’unité de Campo, est examinée en combinant géologie structurale, pétrologie magmatique et métamorphique, et géochronologie. Les résultats de cette étude (1) apportent des contraintes sur les relations thermiques et mécaniques entre le pluton et l’encaissant pendant sa mise en place dans la croûte moyenne, (2) décrivent les mécanismes d’ascension de magmas mafiques au travers de la croûte continentale et (3) documentent l’exhumation et le refroidissement de l’unité de Campo et de l’unité sus-jacente de Grosina pendant la formation de la marge riftée adriatiqueThis study aims to unravel tectonic, magmatic and metamorphic processes active at midcrustal levels from the Permian to the exhumation of the rocks during the Mesozoic riftings by focusing on a Permian gabbro in the Austroalpine nappes (N–Italy, SE–Switzerland). The evolution of the Sondalo gabbro, emplaced in the Campo unit, is examined by combining structural geology, magmatic and metamorphic petrology, and geochronology. The results of this study bring constrains on (1) the thermal and mechanical relationship between the pluton and the host rock during its emplacement in the middle crust, (2) the mechanisms of mafic magmas ascent through the continental crust and (3) the exhumation and cooling history of the Campo unit and the overlying Grosina unit during the formation of the Adriatic rifted margin
22
Fachmann, Stefan. « Geologische Entwicklung im Umfeld des Mahanadi-Riftes (Indien) ». [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962679046.
Texte intégral
23
Ballot, Andreas. « Cyanobacteria in Kenyan Rift Valley lakes a biological and toxicological study / ». [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/116/index.html.
Texte intégral
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Baudouin, Céline. « Volcanisme alcalin associé à l'initiation de la rupture continentale : Rift Est Africain, Tanzanie, bassin de Manyara ». Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT114/document.
Texte intégralRésumé :
Le rift Est africain (REA) est une frontière de plaque en extension. Ce rift présente plusieurs stades d’extension, de l’initiation du rift en Tanzanie jusqu’à l’accrétion océanique en Afar. Le bassin de Manyara se situe le plus au sud de branche Est du REA. Il est caractérisé par la présence de volcanisme récent (< 1,5 Ma) et d’un essaim sismique dans la croûte inférieure (20 – 40 km). De par sa localisation et son contexte tectonique, le bassin de Manyara offre l’opportunité d’étudier le stade le plus précoce de l’initiation du rift. Le bassin de Manyara est composé de plusieurs types de laves hyperalcalines, les néphélinites magnésiennes (Mg# > 55) (Labait, Kwaraha), de calciocarbonatite (Kwaraha) et des néphélinites différenciées (Mg# < 35) (Hanang).Les néphélinites magnésiennes (Labait et Kwaraha) sont des laves primaires composées d’olivines et de clinopyroxènes (cpx). La modélisation géochimique des éléments en trace suggère que ces magmas primaires résultent d'un degré de fusion partielle ≤ 1 % à partir d'une péridotite à grenat et phlogopite. Ces magmas proviennent d’une profondeur > 120 km (présence de xénolites avec des conditions d’équilibre > 4 GPa). Les minéraux ont cristallisés à partir d’un magma pauvre en eau (0,1 et 0,5 pds % H2O). La calciocarbonatite et les néphélinites différenciés sont issues des néphélinites magnésiennes par cristallisation fractionnée et processus d’immiscibilité. Les néphélinites du Hanang sont riches en éléments alcalins (9,5 – 12,1 pds % Na2O+K2O) et en silice (44,2 – 46,7 pds% SiO2) et sont composés de cpx, grenat, néphéline, titanite et apatite. La zonation complexe dans les cpx (par exemple, changement brusque de Mg#, Nb/Ta, et H2O) implique une différenciation magmatique en système ouvert avec immiscibilité de liquide carbonaté et silicaté ainsi qu’un remplissage de la chambre magmatique avec des liquides primaires. La faible teneur en eau des cpx (3 – 25 ppm H2O) indique la présence d’un magma pauvre en eau (0,3 pds % H2O) lors de la cristallisation des cpx à des conditions crustales (340 – 640 MPa et 1050 – 1100 °C). L’étude des inclusions vitreuses dans les néphélines de Hanang permet de contraindre l'évolution magmatique tardive des néphélinites et le comportement des éléments volatils (CO2, H2O, S, F, Cl) lors du stockage et de la remontée du magma. Les inclusions vitreuses sont composées d’un verre trachytique, d’une phase carbonatée et d’une bulle de rétraction. Le verre trachytique contient du CO2 (0,43 pds % CO2, analyses SIMS), du soufre (0,21 à 0,92 pds% S), du chlore (0,28 – 0,84 pds % Cl) et très peu d’H2O (< 0,1 pds % H2O, analyses Raman). Le processus d’immiscibilité conduisant à la formation du carbonate se produit dans un système fermé pendant l'ascension rapide du magma, entre 200 – 500 MPa. La phase carbonatée est un carbonate anhydre et riche en Ca-Na-K-S (33 pds % CaO, 20 pds % Na2O, 3 pds % K2O, et 3 pds % S). Le liquide pré-immiscible a une composition phonolitique avec 6 ± 1,5 pds % CO2 à une pression de 700 MPa. Une étude préliminaire des inclusions par spectroscopie XANES et des roches par spectroscopie Mössbauer a permis de déterminer que les laves de Manyara se sont formées à conditions oxydantes (~ ∆FMQ +1,5).À l’initiation du rift, le volcanisme dans le bassin de Manyara est caractérisé par des magmas riches en CO2 et pauvres en H2O issus d’au moins 120 km de profondeur sous l'escarpement du rift. La présence de ces magmas riches en CO2 et la faible quantité de roches volcaniques émises à la surface peuvent indiquer que le piégeage et la percolation de ces magmas en profondeur est un déclencheur potentiel des essaims sismiques profondsEast African Rift (EAR) is the divergent plate boundary. EAR exposes different stages of extension, from early stage rifting in Tanzania to oceanic accretion in Afar (Ethiopia). Manyara basin is the southernmost rift system of the east branch of EAR with recent volcanism (< 1.5 Ma) and a seismic swarm in the lower crust (20 – 40 km). Due to its location and tectonic setting, the Manyara basin offers the opportunity to study the earliest stage of rift initiation. Manyara volcanism is composed of several types of hyper-alkaline lavas as Mg-nephelinites (Mg# > 55) (Labait, Kwaraha), calciocarbonatite (Kwaraha) and evolved nephelinites (Mg# < 35) (Hanang).Mg-nephelinites (Labait and Kwaraha) are primary lavas mainly composed of olivine and clinopyroxene (cpx). Geochemical modelling from trace elements suggests that these primary magmas result from a degree of partial melting < 1 % from a CO2-garnet-phlogopite-bearing peridotite. These magmas have an asthenospheric source at depth > 120 km (lava carries xenoliths with equilibrium conditions > 4 GPa). The minerals were crystallized from a magma with a low H2O content (0.1 and 0.5 wt% H2O). The calciocarbonatite and evolved nephelinites are derived from Mg-nephelinites by fractional crystallization and immiscibility processes. Hanang nephelinites are silica- and alkaline-rich lavas (44.2 – 46.7 wt % SiO2, 9.5 –12.1 wt % Na2O+K2O, respectively) composed by cpx, Ti-garnet, nepheline, apatite and titanite. Complex zonation of cpx (e.g. abrupt change of Mg#, Nb/Ta, and H2O) and trace element patterns of nephelinites record magmatic differentiation involving open system with carbonate-silicate immiscibility and primary melt replenishment. The low H2O content of cpx (3 – 25 ppm wt. H2O) indicates that at least 0.3 wt % H2O was present at depth during carbonate-rich nephelinite crystallization at 340 – 640 MPa and 1050 – 1100 °C. The study of hosted-nepheline melt inclusions from Hanang allows constraining the late magmatic evolution of nephelinites during storage and magma ascent. Melt inclusions are composed by a silicate trachytic glass, a carbonate phase and a shrinkage bubble. Trachytic glass contains high content in CO2 (0.43 wt %, SIMS analyses), sulfur (0.21 – 0.92 wt % S), chlorine (0.28 –0.84 wt % Cl) and H2O low content (< 0.1 wt %, Raman analyses). Immiscibility process leading to the formation of carbonate occurs in a closed system during rapid magma ascent between 200 – 500 MPa. The carbonate phase is a Ca-Na-K-S-rich and anhydrous carbonate (33 wt % CaO, 20 wt % Na2O, 3 wt % K2O, and 3 wt % S). The pre-immiscible liquid has a phonolitic composition with 6 ± 1.5 wt % CO2 at 700 MPa. A preliminary study of melt inclusions by XANES spectroscopy and whole rocks by Mössbauer spectroscopy was used to determine these Manyara lavas were formed at oxidizing conditions (~ ΔFMQ +1.5).The early stage rifting volcanism (Manyara Basin) is characterized by CO2-rich and H2O-poor magmas from at least 120 km below the rift escarpment. The presence of CO2-rich magmas and the small amount of volcanic rocks erupted at the surface may indicate that the storage and percolation of these magmas at depth is a potential trigger for deep seismic swarms
25
Simon, Brendan. « Rift du Lac Albert, Ouganda, Rift Est Africain : déformation, érosion, sédimentation et bilan de matière depuis 17 Ma ». Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S175/document.
Texte intégralRésumé :
L'objectif de ce travail est (1) d'étudier les relations existant entre déformation, érosion et sédimentation et (2) de quantifier les bilans érosion – sédimentation dans un rift continental en domaine tropical : le rift Albert, localisé au nord de la branche ouest du Rift est-africain. Cette étude consiste en une triple analyse de la déformation, du remplissage sédimentaire (biochronostratigraphie, sédimentologie et stratigraphie séquentielle) et des formes du relief (géomorphologie) basée sur l'interprétation de données de subsurface et d'affleurement. Un modèle d'âge des sédiments a été obtenu en combinant données biostratigraphiques, corrélations séquentielles et courbes de variations des paléoprécipitations. L'analyse sédimentologique a permis de caractériser (1) la source des sédiments et (2) le milieu de sédimentation qui consiste en un lac pérenne profond (<100 m) alimenté par des dépôts de crues, sans cônes alluviaux significatifs. Couplée à l'analyse des formes du relief, cette étude sédimentologique permet reconstituer l'évolution du bassin et de sa déformation: (1) 55-45 Ma : formation de latérites correspondant à la Surface africaine; (2) 45-22 Ma : dégradation de la Surface africaine à la faveur d'un début de surrection du dôme est-africain et formation d'une pédiplaine dont le niveau de base est l'Océan atlantique; (3) 17-2.5 Ma : initiation du bassin du Lac Albert aux alentours de 17 Ma et création de niveaux de base locaux auquel s'adaptent trois pédiplaines correspondant chacune aux trois dépocentres (Lacs Albert, George et Edward) – la surrection du dôme est-africain se poursuit; (i) 17 à 6.2 Ma : stade bassin « flexural » (vitesse de subsidence : 150-200 m/Ma ; vitesse de sédimentation : 1,3 km3/Ma entre 17 et 12 Ma et 0,6 km3/Ma entre 12 et 6 Ma) – les dépôcentres (localisés au sud) sont peu contrôlés par des failles; (ii) 6.2 à 2.5 Ma : stade rift 1 (vitesse de subsidence : > 500 m/Ma jusqu'à 600-800 m/Ma; vitesse de sédimentation : 2,4 km3/Ma) – paroxysme d'activité du rift; (4) 2.5-0.4 Ma : surrection de la Ruwenzori et changement de type de système alluvial à l'incision d'un réseau de drainage - stade rift 2 (vitesse de subsidence : 450 à 250 m/Ma; vitesse de sédimentation : 1,5 km3/Ma); (5) 0.4-0 Ma : flexuration initiation de la dépression du Lac Victoria, inversion du réseau de drainage et création de l'escarpement. La mesure du bilan-érosion sédimentation montre des ordres de grandeur identiques, avec, entre 17 et 2,5 Ma, un excès de matériel érodé (22 000 km3) par rapport aux sédiments déposés (19 000 à 18 000 km3). De 16%, cette différence de volume peut s'expliquer par la forte érosion chimique qui prévaut durant cette période, laquelle est péjorée par la différence de nature des argiles entre le bassin versant (kaolinites) et le bassin (smectites dominante), la néoformation de smectites à partir de kaolinites requérant des apports d'éléments disponibles dans les solutions issues de l'altération chimique des rochesThe aim of this work is (1) to study the relationships existing between deformation, erosion and sedimentation and (2) to quantify the erosion-sedimentation budget in a continental rift: the Rift Albert located in Uganda, in the north of the Western Branch of the East African Rifts. This study consists in a triple analysis of the deformation, the sedimentary infilling (biochonostratigraphy, sedimentology and sequence stratigraphy) and the landforms (geomorphology) based on the interpretation of subsurface and surface data. An age model of the sedimentary infilling has been obtained by combination of biotratigraphic data, sequential correlations and paleoprecipitation variation curves. The sedimentological analysis led to the characterization (1) of the sediments source – most of the quartz grains coming from the erosion of a lateritic profile (with low transportation) – and (2) of the depositional environment which consist of perennial deep (<100 m) feeding by flood deposits, without evidences of alluvial fan. This sedimentological study, along with the analysis of landforms allow to reconstitute the evolution of the basin and of its deformation: (1) 55-45 Ma: formation of laterites corresponding to the African Surface during the very humid period of the Lower-Middle Eocene; (2) 45-22 Ma: stripping of the African Surface in response of the beginning of the East-African Dome uplift and formation of a pediplain connected to the Atlantic Ocean; (3) 17-2.5 Ma: Initiation of the Lake Albert Basin around 17 Ma and creation of local base levels (Lake Albert, Edward and George) on which three pediplains tend to adapt; (i) 18—16 to 6.2 Ma: "Flexural" stage (subsidence rate: 150-200 m/Ma; sedimentation rate 1.3 km3/Ma between 17 and 12 Ma and 0.6 km3/Ma from 12 to 6 Ma) – depocenters location poorly controlled by fault; (ii) 6.2 Ma to 2.5 Ma: Rift stage 1 (subsidence rate: > 500m/Ma up to 600-800 m/Ma; sedimentation rate: 2.4 km3/Ma) – Rifting climax; (4) 2.5-0.4 Ma: uplift of the Ruwenzori Mountains and shifting from an alluvial system to a network of bedrock river incision – Rift Stage 2 (subsidence rate: 450 to 250 m/Ma; sedimentation rate: 1.5 km3/Ma); (5) 0.4-0 Ma: long wavelength downwarping, initiation of the Lake Victoria trough, drainage network inversion and uplift of the present-day escarpment.The measurement of the erosion-sedimentation budget show the same order of magnitude with, between 17 and 2.5 Ma, an excess of eroded material (22 000 km3) compared to the sediment volume deposited in the basin (19 000 to 18 000 km3). This difference of volume of 16% can be explained by the high chemical erosion occurring during this period, which one is depreciated by the difference of mineralogy of the clays between the catchment (kaolinites) and the sedimentary basin (dominantly smectites), the neoformation of smectites from kaolinites needing the input of element available in the solution resulting from the chemical weathering of the substratum
26
Näslund, Jonas. « Rift Valley fever development of diagnostics and vaccines / ». Umeå : Department of Clinical Microbiology, Umeå university, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-30676.
Texte intégral
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Ebinger, Cynthia Joan. « Tectonic model of the Malaŵi Rift, Africa ». Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/15058.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND LINDGREN.
Includes bibliographies.
by Cynthia Joan Ebinger.
M.S.
28
Riccomini, Claudio. « O Rift Continental do Sudeste do Brasil ». Universidade de São Paulo, 1990. http://www.teses.usp.br/teses/disponiveis/44/44136/tde-18032013-105507/.
Texte intégralRésumé :
O Rift continental do Sudeste do Brasil (RCSB), de idade cenozóica, é uma feição alongada e deprimida, desenvolvida entre as cidades de Curitiba (PR) e Niterói (RJ), numa extensão de pelo menos 800 km. Segue grosseiramente a linha de costa atual, da qual dista em média cerca de 70 km, alcançando o Atlântico na sua terminação nordeste. O segmento mais contínuo desse rift, entre as cidades de São Paulo (SP) e Volta Redonda (RJ), com cerca de 350 km de comprimento, foi objeto de estudo no presente trabalho, no tocante aos seus aspectos de tectonia e sedimentação. Com base principalmente na análise microestrutural e na análise de fácies sedimentares, amparadas em dados mineralógicos, palinológicos, geocronológicos e geomorfológicos, entre outros, pôde ser estabelecida de forma tentativa, a seguinte seqüência de eventos para a área estudada: a) Paleógeno (Eoceno-Oligoceno): formação da depressão original (hemi-graben), contínua na porção analisada, como resultado do campo de esforços extensionais de direção NNW-SSE imposto pelo basculamento termomecânico na Bacia de Santos; preenchimento vulcano-sedimentar sintectônico (Grupo Taubaté), compreendendo um sistema de leques aluviais associados à planície aluvial de rios entrelaçados (Formação Resende), basal e lateral na bacia, um sistema playa-lake (Formação tremembé), e um sistema fluvial meandrante (Formação São Paulo); eclosão de derrames de basanito a sudeste de Volta Redonda (Basanito Casa de Pedra), associados ao sistema fanglomerático; condições climáticas inicialmente semi-áridas, durante a sedimentação das formações Resende e Tremembé, passando para úmidas durante a deposição da Formação São Paulo; b) Neógeno (Mioceno ?): transcorrência sinistral de direção E-W, com extensão NW-SE e localmente compressão NE-SW; geração de soleiras (Arujá, Queluz, entre outras) relacionadas à transpressão, ou bacias tipo pull-apart (sistema fluvial entrelaçado da Formação Itaquaquecetuba), associadas à transtração ou relaxamento final dos esforços dessa fase; separação das drenagens dos rios Tietê e Paraíba do Sul pela Soleira de Arujá, com mudança do nível de base e erosão na porção central da Bacia de Taubaté; c) Plioceno (?) a Pleistoceno Inferior: implantação de novo sistema fluvial meandrante (Formação Pindamonhangaba), na área da Bacia de Taubaté, em condições provavelmente quentes e úmidas; d) Pleistoceno Superior: inicialmente fase de estabilidade tectônica com a deposição de sedimentos colúvio-aluviais, frutos do remodelamento do relevo em função das variações climáticas; ao final, nova fase transcorrente E-W, agora dextral, com compressão NW-SE e geração de novas soleiras; definição de distribuição atual dos sedimentos nas bacias, ou embaciamentos, num arranjo lazy-Z; e) Holoceno: nova extensão NW (WNW) - SE (ESE), afetando depósitos de baixos terraços ligados à evolução da rede de drenagem do Rio Paraíba do Sul; f) Atual: campo de tensões indicando compressão, sugestivo de nova mudança no regime de esforços. A alternância entre transcorrência sinistral e dextral e, conseqüentemente, de esforços trativos para compreensivos, respectivamente, estaria relacionada provavelmente ao balanço entre as taxas de abertura na Cadeia Meso-Atlântica e de subducção da Placa de Nazca sob a Placa Sul Americana. A deriva desta última para oeste, em relação às estruturas antigas do RCSB, proporcionaria transcorrência dextral quando a taxa de abertura excedesse a de subducção e transcorrência sinistral no caso oposto. O quadro tectono-sedimentar estabelecido apresenta implicações para a geologia econômica e de engenharia da área de estudo, sendo apresentadas breves considerações a esse respeito ao final do trabalho.The Continental Rift of Southeastern BraziI (CRSB), of Cenozoic age, is an elongate, narrow trough more than 800 km long, between the cities of Cutiriba (Paraná State) and Niterói (Rio de Janeiro State). It roughly parallels the present-day coastline, reaching the Atlantic Ocean in the northeast. The segment of the rift located between the cities of São Paulo (S. Paulo State) and Volta Redonda (Rio de Janeiro State) was the objetc of tectonic and sedimentary analysis. As a result of microstructural analysis, and the study of sedimentary facies, supported by mineralogical, palynological, geochronological, geomorphological and other data, it was possible to reconstruct the Tertiary-Quaternary tectonic and sedimentary history of the study area as follows: a) Palaeogene (Eocene-Oligocene): formation of the original depression (half-graben), continuous over the entire study area, as a result of NNW-SSE extension related to thermomechanical tilting of the adjoining offshore Santos Basin; syntectonic volcanism and sedimentation (Taubaté Group) with a basal and marginal alluvial fan/fluvial braided system (Resende Formation), a playa-lake system (Tremembé Formation), and an upper fluvial meandering system (São Paulo Formation); basanite lava flows, southeast of Volta Redonda (Casa de Pedra Basanite), associated with the Resende Formation; paleoclimatic conditions initially semi-arid during the deposition of the Resende and Tremembé Formations, gradually becoming humid during the sedimentation of the São Paulo Formation; b) Neogene (Miocene ?): Ieft-lateral E-W transcurrence, with NW-SE extension and local NE-SW compression; generation of structural highs (Arujá, Queluz and others) related to transpression, and pull-apart basins (fluvial braided system of the Itaquaquecetuba Formation) associated with transtension or final relaxation of the stress of this phase; separation of Tietê and Paraíba do Sul drainage systems by the Arujá Structural High, with changes in base level and consequent erosion in the westcentral part of the Taubaté Basin; c) Pliocene (?) - Early Pleistocene: installation of a new fluvial meandering system (Pindamonhangaba Formation) in the Taubaté Basin, probably under warm and humid paleoclimatic conditions; d) Late Pleistocene: initially tectonic stability with the deposition of colluvium and alluvium related to morphogenetic evolution as a function of climatic changes; at the and of epoch renewed E-W transcurrent phase, now right-lateral, with NW-SE compression; generation of new structural highs; surface distribution of sedimentary deposits in a lazy-Z pattern; e) Holocene: extensional NW (WNW) - SE (ESE) regime affecting low terrace deposits related to the evolution of the Paraíba do Sul drainage system; f) Present-day: compressive stress-field, suggestive of a new change in the stress regime. The alternation from sinistral to dextral transcurrence is probably related to the interplay between the rates of opening along the Middle Atlantic Ridge and subduction of the Nazca Plate beneath the South American Plate. The effect of westward drift of the South American Plate on the NE-trending basement structures of the CRSB has generated dextral transcurrence when the expansion rate in the east has exceeded the subduction rate in the west and sinistral transcurrence in the opposite case. This tectono-sedimentary picture has significant implications for the economic and engineering geology of the study area, especially with respect to neotectonics and mineral exploration.
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Lumley, Sarah. « Survival strategies of Rift Valley fever virus ». Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/847025/.
Texte intégralRésumé :
Rift Valley fever phlebovirus (RVFV) is an arbovirus of medical and veterinary importance causing severe disease and mortality in humans and ruminants in endemic regions in Africa and the Arabian Peninsula. Understanding the capability, and limiting factors, of temperate British mosquitoes to support replication and transmission of RVFV is critical in order to understand the potential for RVFV establishment were it introduced to the UK. Using in vitro cell culture the effect of temperature on viral replication kinetics independently of the mosquito was investigated; demonstrating temperatures below 20 ̊C negatively affect RVFV replication. The full replication cycle was supported at 20 ̊C in vitro, and this was confirmed within in vivo mosquito experiments with wild-caught Aedes detritus demonstrating a transmission potential for RVFV at 20 ̊C and 25 ̊C. Experiments with two colonised lines of Cx. pipiens further demonstrated the transmission potential for RVFV by mosquitoes present in the UK. A novel RNA in situ hybridisation technique substantiated this result showing widespread dissemination of virus from the primary site of infection and evidence of secondary sites of replication within a single mosquito. Characterisation of the consensus sequence of RVFV propagated within these British mosquitoes in comparison to an in vivo mouse model showed potential for virus adaptation when switching between disparate hosts. Reproducible changes at the consensus level within each host had not previously been shown in early passages of RVFV in studies utilising in vitro models of replication. This suggests that RVFV replication generates genomic variation that may lead to adaptations that could promote potential survival in temperate regions. Taken together these findings indicate that transmission of RVFV within the UK by indigenous mosquitoes is possible. However, factors affecting mosquito survival including temperatures greater than 20 ̊C and ingestion of the higher virus dose (10^7 PFU/mL) will limit the likelihood of such events occurring.
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С, Власенко В. « ВІРТУАЛЬНА РЕАЛЬНІСТЬ. OCULUS RIFT – ШОЛОМ ВІРТУАЛЬНОЇ РЕАЛЬНОСТІ ». Thesis, Київ, Національний авіаційний університет, 2015. http://er.nau.edu.ua/handle/NAU/19299.
Texte intégralRésumé :
Віртуальна реальність – це створений технічними засобами світ, в якому людина відчуває себе близько до того, як вона відчуває себе в реальному світі. Метою розробників є досягти найкращого «ступеня занурення» – це ступінь того, наскільки людина поводить і відчуває себе у віртуальній реальності ніби у спарвжньому світі. Тому технології віртуальної реальності постійно розвиваються. Однією з перших таких технологій можна вважати німе кіно, а однією з останніх – застосування шоломів або окулярів віртуальної реальності. Після того, як людина одягає на себе такі окуляри, все, що вона бачить – це віртуальний світ. Це головна відмінність окулярів віртуальної реальності від окулярів доповненої реальності.
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RUSSO, ELENA. « The anomaly of rift-parallel transcurrent faults ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/306312.
Texte intégralRésumé :
Fratture parallele a zone di rift con componenti di movimento trascorrente e obliquo, sviluppate in superficie e all’interno dei primi dieci chilometri della crosta, sono state documentate in contesti vulcano-tettonici estensionali attraverso il calcolo di meccanismi focali e la raccolta di dati di terreno di età olocenica. L’origine e lo sviluppo di queste strutture sono tuttora indefiniti: la presenza di componenti trascorrenti lungo fratture estensionali e faglie normali è infatti incompatibile con lo stato di stress all’origine di zone di rift, e, inoltre, una cinematica trascorrente lungo piani paralleli a faglie normali, come quella individuata, non risulta compatibile con i processi estensionali all’origine della formazione di un rift. Quest’anomalia è di estremo interesse per la comunità scientifica internazionale: infatti, interpretare correttamente dati geofisici associati alla risalita di magma, che causa la formazione di faglie e fratture estensionali in superficie, è fondamentale per un corretto monitoraggio di aree vulcaniche attive.
Questa ricerca di dottorato si focalizza in particolare sul plateau vulcanico di Yellowstone, negli Stati Uniti occidentali, e sui rift del Theistareykir e Krafla, all’interno della Northern Volcanic Zone in Islanda nordorientale. Gli obiettivi principali sono l’individuazione di piani di faglia con diversa cinematica, lo studio delle relazioni temporali tra faglie trascorrenti/transtensive e faglie normali e tra faglie trascorrenti/transtensive ed intrusioni magmatiche, e l’analisi della variazione di cinematica con la profondità. Gli obiettivi sopra descritti sono stati raggiunti attraverso un approccio multidisciplinare, che consiste nell’integrazione tra nuovi dati sismologici e dati geologico-strutturali di terreno raccolti attraverso metodi classici e su ortomosaici e modelli digitali del terreno (DSMs) costruiti tramite tecniche di fotogrammetria applicate a rilievi con droni, e modelli numerici incentrati sulla deformazione indotta da dicchi e sill.
I risultati dimostrano che la complessa geometria e distribuzione di strutture trascorrenti parallele ai rift può essere interpretata considerando sia il possibile controllo della tettonica regionale sull’orientazione delle faglie sia la relazione con sciami sismici, la messa in posto di sill e dicchi, che possono causare l’allargamento di fratture pre-esistenti o lo sviluppo di nuove fratture, e con fasi di inflazione e deflazione superficiale.
In particolare, la predominanza di movimenti trascorrenti messa in luce dai meccanismi focali durante lo sciame sismico avvenuto a Madison Plateau (Yellowstone) nel 2010 ha portato allo sviluppo di un modello geomeccanico che spiega l’origine di componenti trascorrenti di movimento, destre o sinistre, in relazione alla propagazione orizzontale di un dicco. Queste fratture si originano in corrispondenza della terminazione del dicco stesso, oppure lateralmente, queste ultime con geometria parallela o sub-parallela al corpo intrusivo, come confermato dai dati di terreno raccolti attraverso metodi classici e rilievi da drone in Islanda e dai modelli numerici che investigano la deformazione risultante ad una propagazione magmatica orizzontale.Fractures with transcurrent and oblique components of motion, parallel and coeval to rift zones, which developed at the surface and in the upper ten kilometers of the crust, have been recently documented in extensional volcano-tectonic contexts through earthquake focal mechanisms and Holocene field data. Their origin and development is still undefined, due to the fact that transcurrent motions both along normal faults and extensional fractures are incompatible with the stress field associated with rift zones and, furthermore, transcurrent movements along planes parallel to normal faults are not compatible with the extension required to form a rift. This anomaly is an issue of international interest for the scientific community: in fact, interpreting correctly geophysical data associated with magma upwelling, which also influences the genesis of faults and extension fractures at the surface, is a key point when monitoring active volcanic zones. The present research focuses on the Yellowstone volcanic plateau, in the western United States, and the Theistareykir and Krafla Fissure Swarms, the westernmost rifts of the Northern Volcanic Zone, in northeast Iceland. Main aim is to define the partition of fault motions at planes with different kinematics, to study the temporal relations between transcurrent/transtensional faults and normal faults, to evaluate the relations between transcurrent/transtensional faults and magmatic intrusions and to analyze the variations of fault kinematics with depth. A multidisciplinary approach has been adopted, that consists in the integration of new geological-structural field data acquired through classical methods, quantitative data collected on Orthomosaics and on Digital Surface Models (DSMs) elaborated through Structure from Motion photogrammetry techniques (SfM) applied to Unmanned Aerial Vehicles (UAVs) surveys, seismic data regarding both earthquakes of magmatic and tectonic origin and numerical models on sill and dyke-induced deformations. The complex geometry and distribution of rift-parallel transcurrent faults is interpreted both considering the possible control of regional tectonics on the orientation of faults and the relation with seismic swarms, magmatic emplacement, that could cause the enlargement of pre-existing fractures or the development of new fractures and small faults, and surficial deformation phases. The predominance of strike-slip motions revealed by focal mechanism solutions during the 2010 Madison Plateau seismic swarm at Yellowstone lead to the development of a geomechanical model that explains the origin of left- or right-lateral kinematics as related to an horizontally-propagating dyke. Such fractures can be located in correspondence of the advancing fluid tip or at the sides of the advancing magmatic body, as confirmed by both field data collected through classical methods and UAV surveys conducted in Iceland and by the numerical models developed to investigate horizontal dyke propagation.
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VETEL, William. « Dynamique de l'extension intra-continentale en contexte de rift magmatique : le Rift Turkana (Nord Kenya) de l'Eocène à l'Actuel ». Phd thesis, Université de Bretagne occidentale - Brest, 2005. http://tel.archives-ouvertes.fr/tel-00009294.
Texte intégralRésumé :
La dynamique de l'extension continentale et la géométrie des rifts qui en découlent sont régies par la combinaison de nombreux paramètres (thermiques, mécaniques, cinématiques) qui interagissent à différentes échelles, dans le temps et dans l'espace. L'exemple choisi dans cette étude, afin d'apporter des éléments de réponse à la compréhension de la mise en place des structures extensives, est celui du rift Turkana (Nord Kenya) qui appartient à la branche est du Rift Est Africain (REA). Cette portion de rift cénozoïque atypique s'est développée selon un axe NS depuis ~45 Ma. entre les terminaisons de deux bassins d'un rift antérieur oblique (bassins Anza-Soudan N140°E Crétacé). Sa structure profonde est dominée par un ensemble d'hemi-grabens syn-rifts oligo-pliocènes et sa géométrie de surface est actuellement marquée par une topographie peu contrastée et une sismicité faible qui rendent difficile l'étude des mouvements récents/actifs dans ce secteur. Ce mémoire, basé sur l'interprétation d'imagerie satellitale Landsat ETM+, corrélée aux données topographiques (SRTM) et aux données de sismique réflexion, permet :
- A l'échelle régionale, une reconstitution tectono-magmatique de l'histoire polyphasée du rift Turkana établie sur la base de cinq cartes ‘restaurées' successives (45-23 Ma., 23-15 Ma., 15-6 Ma., 6-2.6 Ma. et 2.6 Ma.-Actuel), auxquelles ont également été intégrées les structures pré-existantes (socle précambrien, structures crétacées). Ce modèle démontre clairement l'influence de : 1) deux couloirs transverses de socle faillés d'échelle régionale (NKFZ : N'Doto-Karisia N140°E, 100x600 km ; KBFZ : Kataboi-Buluk N50°E, 30x250 km) et 2) de domaines magmatiques, sur la nucléation et la propagation des structures extensives à différents stades du rifting. Les bassins syn-rifts se développent et migrent en premier lieu à l'intérieur du couloir N140°E NKFZ à la faveur de relations angulaires entre les structures N140°E et les failles néoformées NS, ces dernières sont par la suite bloquées lors de leur interaction avec les structures N50°E KBFZ qui peuvent également agir comme des zones de transfert et aboutissent à l'élargissement de la zone riftée (200x200 km). La description des relations entre les domaines magmatiques et la déformation met en avant le rôle déterminant des structures internes des dômes volcaniques (fentes d'extrados, failles syn-magmatiques) sur la propagation des bassins à travers ces paleo-dômes après cessation de l'activité magmatique.
- A l'échelle lithosphérique, les interactions panache/lithosphère durant la migration de la plaque Afrique (~1000 km vers le NE) depuis 50 Ma. à la verticale de deux plumes cénozoïques permettent de proposer deux hypothèses sur l'absence de soulèvement thermique le long de la dépression du Turkana. Il peut s'agir, soit de la migration latérale de la tête du panache sous la lithosphère pré-étirée crétacée selon un mécanisme de ‘thin-spot', soit du ‘durcissement' de cette même lithosphère en réponse au refroidissement du matériel mantellique sous-plaqué (crétacé) qui entrave le soulèvement de l'ensemble de la zone.
- Concernant les déformations récentes/actives (<5 Ma.) du rift Turkana, l'étude du développement des inversions tectoniques positives (<3.7 Ma.), distribuées uniquement dans les bassins situés à la verticale du couloir transverse N140°E NKFZ, confirme l'importance du rôle joué par cette discontinuité de premier ordre sur l'évolution du rift Turkana depuis l'Eocène jusqu'à l'Actuel. La reconstitution de la mise en place de ces structures compressives aboutit à un modèle cinématique polyphasé comprenant les trois stades suivants : 1) un régime purement extensif avant 5 Ma. (σ3 horizontal orienté EW, σ1 vertical), 2) une rotation horaire (~20°) de l'axe σ3 entre 5 et 3.7 Ma. qui entraîne la réactivation en dextre de la NKFZ et la formation d'un réseau de fractures N20°E et 3) un stade compressif (permutation des axes σ1/σ2) accompagné de la rotation horaire de σ3 (~20°) qui induit la réactivation en inverse des failles N20°E après 3.7 Ma.
- A l'échelle plus locale, dans la partie orientale du rift Turkana, le réseau récent (<3 Ma.) de failles N170°-N10°E du Kino Sogo (150x40 km) s'organise selon une succession régulière de horsts et grabens, exceptionnellement bien exposés, qui recoupent des laves mio-pliocènes peu épaisses (~200 m) mises en place sur un horst asymétrique de socle, limité par des structures N140°E, N50°E et NS. L'étude géométrique et statistique de la population de failles du Kino Sogo révèle plusieurs particularités : 1) ce réseau accommode peu d'extension (<1%) et implique des taux d'extension et de déformation faibles (~0.1 mm/an et 10-16 s-1, respectivement), 2) l'analyse des longueurs de failles se corrèle avec une loi mathématique de type exponentielle en opposition avec celles classiquement admises de type lois de puissances, et 3) malgré des longueurs importantes (9-40 km), les failles présentent des rejets ≤ 100 m, ce qui leur confère un rapport rejet/longueur inférieur à ceux décrits sur des réseaux de failles similaires. Ce caractère mature, mais sous-déplacé des failles, est attribué à un modèle de croissance de failles dominé par la réactivation de structures pré-existantes présentes dans le socle sous-jacent (foliation/failles) ou au toit d'un paléo-dôme volcanique antérieur.
- Enfin, d'un point de vue méthodologique, l'intérêt de l'étude des réseaux de drainage en contexte morphologique peu contrasté est confirmé par une analyse détaillée de l'intense réseau de drainage développé dans le secteur occidental du Turkana. En effet, l'interprétation structurale de trois anomalies de drainage met en évidence : 1) la déviation de la rivière Turkwell (NS puis EW) le long d'un couloir transverse faillé EW intra-socle de second-ordre (Turkwell-Mont Porr ; ~20x100 km), 2) le blocage d'un réseau dense de rivières par la réactivation récente (<5 Ma.) du plan de faille bordière Ouest Napedet d'âge oligo-miocène 3) la formation d'une anomalie de type circulaire autour d'une structure antiforme initiée lors de l'inversion d'un dépocentre au pied de la faille de Kerio et associée aux inversions tectoniques positives décrites pour la période récente (<3.7 Ma) dans une partie du rift Turkana.
D'une façon générale, ce travail apporte des résultats et des modèles nouveaux ayant des implications directes sur l'étude de la nucléation et de la propagation des bassins syn-rifts et des réseaux de failles associés aux segments de rift magmatiques marqués par un héritage structural important (socle, système rifté antérieur).
33
Vetel, William. « Dynamique de l'extension intra-continentale en contexte de rift magmatique : le Rift Turkana (Nord Kenya) de l'Eocène à l'Actuel ». Brest, 2005. https://tel.archives-ouvertes.fr/tel-00009294.
Texte intégralRésumé :
La géométrie du rift cénozoïque du Turkana (45 Ma. , Nord Kenya) est dominée par un ensemble de bassins syn-rifts oligo-pliocènes et une topographie peu contrastée. Ce mémoire, basé sur l'imagerie Landsat ETM+, des données topographiques et de sismique réflexion, permet une reconstitution de l'évolution du rift Turkana depuis 45 Ma. Qui démontre l'influence de deux couloirs transverses de socle et du magmatisme sur le développement des structures extensives. L'étude des inversions tectoniques positives récentes/actives (<3. 7 Ma aboutit à un modèle cinématique en trois stades pour les 5 derniers Ma. L'étude géométrique et statistique du réseau de failles récent (<, Ma. ) du Kino Sogo révèle : 1) ce réseau accommode peu d'extension et implique des taux d'extension et de déformation faibles, 2) les longueurs de failles se corrèlent avec une loi mathématique exponentielle, et 3) les failles ont des rejets <_ 100 m, ce qui leur confère un rapport rejet/longueur faible. Ce caractère mature, mais sous-déplacé des failles, est attribué à un modèle de croissance de failles dominé par la réactivation de structures pré-existantes. Enfin, l'analyse du réseau de rivières du Turkana permet de discuter trois anomalies de drainage: 1) la déviation de la rivière Turkwell le long d'un couloir transverse faillé intra-socle, 2) le blocage d'un réseau dense de rivières par la réactivation récente d'un plan de faille oligo-miocène, et 3) la formation d'une anomalie de type circulaire initiée lors de l'inversion récente des bassins (<3. 7 Ma). D'une façon générale, ce travail apporte de nouveaux résultats sur la mise en place de rifts magmatiques marqués par un héritage structural importantThe geometry of the Turkana Cenozoic rift (45 Ma. , North Kenya) is dominated by a set of syn-rift oligo-pliocene basins and a subdued topography. This manuscript, based on satellite imagery (Landsat ETM+), topographical data (SRTM) combined with seismic reflexion, proposes a model for the Turkana rift evolution for the last 45 Ma. That demonstrates the influence of two transverse basement faulted corridors and of magmatic domains on the extensional structures development. The study of recent/active tectonic inversions leads us to propose a three-stages kinematic model for the last 5 Ma. The geometrical and statistical study of the recent (<3 Ma. ) Kino Sogo fault bel reveals : 1) this network accommodates a weak extension implying low extensional and strain rates, 2) fault lengths fit with exponential law, and 3) fault throw are 5100 m leading to a weak throw/length ratio. This mature, but under-displaced character of faults, is attributed to a fault growth model dominated by the rejuvenation of pre-existing structures. Finally, the Turkana river network analyses leads us to discuss three drainage anomalies: 1) the virgation of the Turkwell river along a transverse basement faulted corridor, 2) the lock of a dense river pattern by the recent reactivation of an oligo-miocene fault plane, and 3) the formation of a circular-type drainage anomaly in response to the recent tectonic inversions of the basins (3. 7 Ma. ). More generally, this work supplies some new insights on the development of magmatic rifts controlled by a strong structural inheritance
34
Vetel, William Le Gall Bernard. « Dynamique de l'extension intra-continentale en contexte de rift magmatique le Rift Turkana (Nord Kenya) de l'Eocène à l'Actuel / ». [S.l.] : [s.n.], 2005. http://tel.ccsd.cnrs.fr/docs/00/04/80/57/PDF/tel-00009294.pdf.
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Abid, Iftikhar A. « Mixed-layer illite/smectite diagenesis in the rift and post-rift sediments of the Jeanne d'Arc Basin, offshore Newfoundland, Canada ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25762.pdf.
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Trout, Mark N. « Sediment transport and deposition across active faulted rift margins ». Thesis, University of Leeds, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247727.
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Riley, Teal Richard. « Quaternary volcanism of the Rockeskyll Complex, West Eifel, Germany and the carbonatite-nephelinite-phonolite association ». Thesis, University of Bristol, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260870.
Texte intégral
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Näslund, Jonas. « Rift Valley fever : development of diagnostics and vaccines ». Doctoral thesis, Umeå universitet, Klinisk mikrobiologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-30676.
Texte intégralRésumé :
Rift Valley Fever virus (RVFV) causes an infection with severe impact on animal and human health. The disease is endemic throughout almost the entire African continent and large regions of the Arabian Peninsula. During epidemics, high mortality is observed in animals, especially among cattle, goats, and sheep. In humans, the symptoms vary from a benign influenza-like disease to a life-threatening hemorrhagic fever. Due to the devastating effect on communities in endemic regions and the possibility of further spread of this virus, there is an imperative need to improve and develop control measurements against this emerging disease. Therefore, this thesis focuses on diagnostics and vaccines against RVFV. RVFV infection kinetics was studied in a mouse model system by detection and quantification of viral genomes, using a developed quantitative real-time PCR (QRT-PCR) method. This novel QRT-PCR method proved to be reliable and serves as a supplement to standard diagnostics, direct virus isolation and serological methods. High levels of viral RNA were found in blood and liver samples from experimentally infected mice during the first days post infection. Thereafter the levels declined rapidly and dropped below detection limit approximately seven days post infection. The QRT-PCR technique was also used in a study aimed to improve diagnosis of RVFV from field samples collected on filter strips. Today, the available RVFV vaccines are only approved for animal use and these vaccines have several shortcomings. Since RVFV is a highly pathogenic organism requiring bio-safety level 3 laboratories, two different none-replicating vaccine approaches have been applied and evaluated using a mouse model. A DNA based vaccine, administered via gene-gun, and the use of virus-like particles (VLP), by the intra-peritoneal route. RVFV specific and neutralising antibodies were raised with both vaccine approaches. However, VLP vaccination against Rift valley Fever proved to be more promising as a future vaccine, since higher titres of neutralising antibodies and improved survival rate were found upon a lethal RVFV challenge in mice. In conclusion, a sensitive and specific method for quantifying RVFV infection and a promising vaccine candidate against RVFV were developed.
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Bubeck, Alodie. « Unravelling the kinematic evolution of segmented rift systems ». Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/95297/.
Texte intégralRésumé :
Normal fault systems within incipient rifts comprise an array of small-scale structures, including networks of fractures and small displacement faults (<15 m) that represent the incremental strains that develop during rift propagation. To constrain the evolution of volcanic rift systems, I investigate rift-fault propagation and localisation at a range of scales using laboratory-based mechanical characterisation of host rocks, and high-resolution structural mapping of faults, and fault-related deformation in an incipient (Koa’e fault system, Hawai’i), and evolved (Krafla fissure swarm, Iceland) rift system. Experimental analysis of pahoehoe lava from Kilauea’s south flank, Hawai’i, highlight a distinctive physical and mechanical stratigraphy related to the volume, and geometry, of voids within the lava. The resulting variability in intact strength produces the effect of a multi-layered sequence within a single lava, and will exert significant control on the segmentation and linkage of initial cracks (mm-scale or less) that develop. High- resolution mapping of the distribution, geometry, and kinematics of cm- to km-scale extensional strains in the Koa’e fault system (Hawai’i) and the Krafla fissure swarm (Iceland) also reveals evidence for segmented fault propagation, linkage and non-coaxial strain. This segmentation is a function of the varying natural mechanical anisotropy of the deforming sequence and non-uniform strain rates. Results from the Koa’e and Krafla rifts are compared with break-up related deformation from the NE Atlantic margins to model the evolution of non-coaxial fault sets at the margin scale. Fault and intrusion data from the Faroe Islands and East Greenland highlights geometrically and kinematically comparable structural sets, implying an analogous kinematic evolution of inter-rift strains. I infer that stress transfer during NE Atlantic opening took place by sub-basin scale ancillary faults and dikes, associated with two overlapping, active rift systems in the Paleogene – a NE-propagating Reykjanes ridge, and a SW-propagating Aegir ridge – rather than via transfer fault segmentation.
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Clark, Brett. « Metabolic rift : toward a sociology of ecological crisis / ». view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1283959611&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Texte intégralRésumé :
Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 223-257). Also available for download via the World Wide Web; free to University of Oregon users.
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Morris, Cathryn. « Miracles or myth : the royal Raymond Rife story ». Honors in the Major Thesis, University of Central Florida, 2001. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/236.
Texte intégralRésumé :
This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Arts and Sciences
Film
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Tongue, Jane Anthea. « Seismicity studies in the East African Rift, Kenya ». Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/34972.
Texte intégralRésumé :
An analysis of the microseismicity distribution within Kenya from temporary recording networks shows the activity to be primarily associated with the Kenya Rift and the Nyanza Trough with increased activity in areas of recent volcanic and geothermal activity. A 100km x 80km earthquake recording network was operated for 3 months (Jan-Mar 1990) in the Lake Baringo region of the Kenya Rift Valley. Twenty-nine stations were deployed over a region including the Elgeyo escarpment, the Kerio Valley, the Tugen Hills and the Baringo basin. Eighty local events of ML< 2.0 were located within 50km of the network. These events are situated within the central part of the rift, showing some association with the main rift faults but mainly clustering beneath Lake Baringo at a depth of ~5km and occurring as swarm activity. 90% of the observed activity occurred at depths shallower than 12km indicating that the brittle/ductile transition zone in this area is between 12-16km, which is similar to that in the Lake Bogoria area. Studies of the focal mechanisms of suitable events indicates a WNW-ESE extension direction across the Baringo basin and the presence of subvertical tensional fractures beneath the lake, which are suggested to be caused by the propagation of basic dykes into the crust. The inversion of local P-wave arrival-time data, for the upper crustal velocity structure beneath the Lake Bogoria and Lake Baringo areas, identified velocity lows associated with geothermal areas, a velocity high beneath the Goituimet basaltic lavas and a 10% velocity contrast across the Bogoria-Emsos-Legisianana fault. A model for the lithospheric structure beneath the Baringo basin is proposed with partial melt in the upper mantle beneath the rift, a dyke intruded lower crust with localised intrusions into the mid-upper crust in areas of geothermal and volcanic activity.
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Henry, William John. « A seismic investigation of the Kenya Rift Valley ». Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35038.
Texte intégralRésumé :
In August of 1985 the crustal structure underlying the Kenya rift valley was investigated by long range explosion seismology. The experiment (KRISP85) consisted of two seismic lines in the central sector of the rift, one along the axis (140 km) and the other across it (50 km). Interpretation of the data, including time-term analysis and ray tracing has yielded the following information. The thickness of rift infill varies from about 6 km below Lake Naivasha to about 2 km and 1.5 km below Lake Magadi and Lake Bogoria respectively. The underlying material has a P-wave velocity of 6.05 +/- 0.03 km/s which suggests the rift is underlain by Precambrian metamorphic basement. A localised high velocity zone identified to the east of Nakuru may be associated with basic intrusive material. The P-wave velocity increases discontinuously to 6.45 +/- 0.05 km/s at a depth of 12.5 +/- 1-0 km. This depth is similar to that inferred for the brittle-ductile transition zone from a study of local seismicity in the Lake Bogoria region. A high P-wave velocity layer (7.1 +/- 0.15 km/s) occurs at 22 +/- 2 km depth which might be associated with a sill-like basic intrusion in the lower crust. An upper mantle velocity of 7.5 +/- 0.2 km/s (unreversed) is reached at a depth of 34.0 +/- 2.0 km. This implies that only moderate crustal attenuation has occurred beneath the central sector of the rift. No evidence was obtained for the existence of an "axial intrusion" reaching to shallow levels below the rift and causing crustal separation as suggested by previous studies. Relative residuals determined for 46 teleseismic events recorded by a 15 station, small aperture seismic array in the vicinity of Lake Bogoria indicate considerable lateral heterogeneity in the upper crust. An Aki inversion of the relative residuals has revealed the existence of two distinct low velocity zones which may be associated with magma chambers.
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Baudin, Maria. « Rift Valley fever : consequences of virus-host interactions ». Doctoral thesis, Umeå universitet, Virologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-126602.
Texte intégralRésumé :
Rift Valley fever virus (RVFV) is a mosquito-borne virus which has the ability to infect a large variety of animals including humans in Africa and Arabian Peninsula. The abortion rate among these animals are close to 100%, and young animals develop severe disease which often are lethal. In humans, Rift Valley fever (RVF) presents in most cases as a mild illness with influenza-like symptoms. However, in about 8% of the cases it progresses into a more severe disease with a high case fatality rate. Since there is such a high abortion rate among infected animals, a link between human miscarriage and RVFV has been suggested, but never proven. We could in paper I for the first time show an association between acute RVFV infection and miscarriage in humans. We observed an increase in pregnant women arriving at the Port Sudan Hospital with fever of unknown origin, and several of the patients experienced miscarriage. When we analysed their blood samples for several viral diseases we found that many had an acute RVFV infection and of these, 54% experienced a miscarriage. The odds of having a miscarriage was 7 times higher for RVFV patients compared to the RVFV negative women of which only 12% miscarried. These results indicated that RVFV infection could be a contributing factor to miscarriage. RVFV is an enveloped virus containing the viral glycoproteins n and c (Gn and Gc respectively), where Gn most likely is responsible for the initial cellular contact. The protein DC-SIGN on dendritic cells and the glycosaminoglycan heparan sulfate has been suggested as cellular receptors for RVFV, however other mechanisms are probably also involved in binding and entry. Charge is a driving force for molecular interaction and has been shown to be important for cellular attachment of several viruses, and in paper II we could show that when the charge around the cells was altered, the infection was affected. We also showed that Gn most likely has a positive charge at a physiological pH. When we added negatively charged molecules to the viral particles before infection, we observed a decreased infection efficiency, which we also observed after removal of carbohydrate structures from the cell surface. Our results suggested that the cellular interaction partner for initial attachment is a negatively charged carbohydrate. Further investigations into the mechanisms of RVFV cellular interactions has to be undertaken in order to understand, and ultimately prevent, infection and disease. There is currently no vaccine approved for human use and no specific treatments for RVF, so there is a great need for developing safe effective drugs targeting this virus. We designed a whole-cell based high-throughput screen (HTS) assay which we used to screen libraries of small molecular compounds for anti-RVFV properties. After dose-response and toxicity analysis of the initial hits, we identified six safe and effective inhibitors of RVFV infection that with further testing could become drug candidates for treatment of RVF. This study demonstrated the application of HTS using a whole-cell virus replication reporter gene assay as an effective method to identify novel compounds with potential antiviral activity against RVFV.
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Du, Plessis Gerda. « Actinobacterial diversity of the Ethiopian Rift Valley lakes ». University of the Western Cape, 2011. http://hdl.handle.net/11394/5385.
Texte intégralRésumé :
>Magister Scientiae - MScThe class Actinobacteria consists of a heterogeneous group of filamentous, Gram-positive bacteria that colonise most terrestrial and aquatic environments. The industrial and biotechnological importance of the secondary metabolites produced by members of this class has propelled it into the forefront of metagenomics studies. The Ethiopian Rift Valley lakes are characterized by several physical extremes, making it a polyextremophilic environment and a possible untapped source of novel actinobacterial species. The aims of the current study were to identify and compare the eubacterial diversity between three geographically divided soda lakes within the ERV focusing on the actinobacterial subpopulation. This was done by means of a culture-dependent (classical culturing) and culture-independent (DGGE and ARDRA) approach. The results indicate that the eubacterial 16S rRNA gene libraries were similar in composition with a predominance of α-Proteobacteria and Firmicutes in all three lakes. Conversely, the actinobacterial 16S rRNA gene libraries were significantly different and could be used to distinguish between sites. The actinobacterial OTUs detected belonged to both the Rubrobacterales and Actinomycetales orders with members of the genus Arthrobacter being found in all three lakes. Geochemical properties were significantly different between the lakes, although more than one property attributed to the variance between community compositions. The diversity detected in the culture-based study differed significantly and all isolates belonged to the genus Streptomyces. Two novel strains were characterized by means of phylogenetic (16S rRNA gene sequence), physiological, morphological and biochemical analyses. Both novel isolates were capable of growing under "extreme" conditions- pH 12, 10% NaCl and 45°C. Partial enzyme characterization revealed that both strains produced xylanase enzymes that were active at pH 6.5 and 8.5 with an increase in activity up to 45°C. The results obtained revealed a previously undetected diversity of actinobacteria in the Ethiopian Rift Valley with a potentially novel subpopulation adapted to haloalkaline conditions. The low 16S rRNA sequence similarity of a substantial proportion of the libraries suggests that culture-based isolation may play a vital role in deciphering the community fingerprint.
The National Research Foundation and the Norwegian Research Council
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Abbots, Frances Vivien. « Sedimentology of Jurassic syn-rift resedimented carbonate sandbodies ». Thesis, University of Bristol, 1989. http://hdl.handle.net/1983/08bc3c73-7880-4cfd-afc1-0af2d9e82e18.
Texte intégralRésumé :
This thesis discusses the sedimentology of three contrasting Jurassic carbonate sand turbidite systems from Southern Europe: the Cutri Formation (Bathonian) of Mallorca; the Vajont Limestone (Bajocian-Callovian) of northern Italy; and the Peniche sequence (Toarcian-Aalenian) of the Brenha Formation of western Portugal. These sandbodies all formed in syn-rift extensional settings which imposed a primary morpho-tectonic control on both the source platform and depositional basin morphology. The three sandbodies in question display varying geometries and architectures and are discussed in terms of the palaeogeographic, tectonic and eustatic controls that governed their individual development; as well as being used to test the recently developed apron model against that of the submarine fan. In this context oolitic carbonate aprons associated with palaeowindward and palaeoleeward platform margins have been distinguished. The Cutri Formation is interpreted as a oolitic base-of-slope apron, that displays a minor single syn-rift thinning upward megacycle (retrogradational) trend indicative of subsidence out-pacing sedimentation. The apron correlates with a eustatic sea-level drawdown and was characterised by infrequently laterally correlatable, oolitic turbidite units separated by hemipelagic interbeds. This sandbody is relatively sand-poor in nature, and is interpreted as being sourced from a palaeowindward platform margin. The Vajont Limestone is re-interpreted as an aggraded oolitic apron from its original interpretation as a sub-marine fan. The apron is composed of stacked oolitic grainstone turbidites and is locally up to 800m thick. It is interpreted as being sourced from a stable `keep up' palaeoleeward platform margin, where dominant off-bank sand transport led to development of line-sourced oolitic turbidites, which were actively aggraded by on-going basin subsidence. Statistics were used to demonstrate a random turbidite sequence which enhances the apron interpretation. The Peniche sequence is reconfirmed as a carbonate-siliciclastic fan, its facies development conforming to a siliciclastic sand-rich fan model. Statistical analysis indicates a non-random (cyclic) turbidite sequence, thereby enhancing the fan interpretation. The fan occurs as a localised development within fine-grained basinal facies and correlates stratigraphically with a eustatic sea-level drawdown. Interpreted as being sourced from a palaeoleeward margin, the sequence progradates from outer fan lobes to a thick, multi-storey braided channel complex. These syn-rift resedimented carbonate sandbodies have the potential to be stratigraphically associated with basinal source rocks and therefore may be viewed as prospective hydrocarbon reservoir facies.
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Veiga, Frédéric Daniel Jacinto. « Implementation of the RIF-PRD ». Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6310.
Texte intégralRésumé :
Dissertação para obtenção do Grau de Mestre em
Engenharia InformáticaO Rule Interchange Format (RIF) é uma recomendação da W3C que define um conjunto de dialectos para promover a interoperabilidade entre sistemas de regras. A necessidade destes dialectos proveio de um crescente número de linguagens de regras (lógicas ou de produção), com algumas tão específicas que o intercãmbio de regras entre sistemas diferentes é uma tarefa quase impossível. A criação de uma linguagem de regras convencional não seria bem aceite, como tal, a W3C optou por desenvolver o RIF, com o objectivo de fornecer uma solução para o intercãmbio de regras entre diferentes sistemas. Um dos dialectos do RIF é o Rule Interchange Format Production Rule Dialect (RIFPRD), que define uma linguagem de regras de produção orientada para a SemanticWeb. Até à data actual, não é conhecida nenhuma implementação completa de RIF-PRD, mas uma primeira especificação declarativa completa do RIF-PRD baseada em programação por conjuntos de resposta foi proposta na nona conferência internacional de Semantic Web (ISWC2010). Nesta dissertação implementamos um motor de RIF-PRD baseando-nos nessa especificação, e desenvolveremos outras duas implementações, uma utilizando o sistema de regras de produção Jess, e outra recorrendo ao sistema de programação em lógica XSB. Após terminadas as três implementações, foi feita uma comparação entre elas, com o intuito de verificar se há benefícios em utilizar programação por conjuntos de resposta para implementar RIF-PRD, e concomitantemente detectar eventuais limitações na utilização de programação por conjuntos de resposta.
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Albaric, Julie. « Relations entre déformation active, rhéologie et magmatisme dans un rift continental : Etude sismologique de la Divergence Nord-Tanzanienne, Rift Est-Africain ». Phd thesis, Université de Bretagne occidentale - Brest, 2009. http://tel.archives-ouvertes.fr/tel-00495984.
Texte intégralRésumé :
Les rifts continentaux résultent de l'action de contraintes extensives dont la magnitude est suffisante pour déformer un continent (forces aux limites des plaques, mouvements asthénosphériques). Cette déformation, contrôlée notamment par la rhéologie ou encore l'héritage structural lithosphérique, se réalise par des processus magmatiques (“dyking”) et tectoniques (rupture sur faille et étirement ductile) dont l'importance relative est mal connue et variable d'un segment de rift à l'autre. Afin de mieux comprendre comment ces différents facteurs et processus interagissent, la Divergence Nord-Tanzanienne (DNT) apparaît comme une cible privilégiée du Rift Est-Africain : elle représente un stade précoce du rift et montre une transition abrupte dans le style morphotectonique et l'expression du volcanisme. Cette étude a consisté à déployer un réseau sismologique local dans la DNT et à exploiter les données issues de l'enregistrement continu de l'activité sismique pendant 6 mois (campagne SEISMO-TANZ 2007). Les signaux des séismes proches et lointains sont utilisés comme indicateurs de la sismogénèse, de la résistance crustale, des champs de déformation et de contraintes, et renseignent aussi sur la structure et la fabrique (anisotropie) lithosphérique. La sismicité est essentiellement localisée dans la branche centrale de la DNT, au sud des lacs Natron (sud du volcan Gelaï) et Manyara. La crise sismique observée à Gelaï illustre la co-existence de processus magmatiques et tectoniques, avec la mise en place d'un dyke et le comportement à la fois asismique (glissement lent) et sismique (séisme de magnitude Mw 5.9) de failles normales. Les structures géologiques mises en jeu dans cette crise sont orientées NE-SW, obliques à l'axe ~N-S du rift dans la zone. Cette direction est parallèle à la fabrique tectonique antérieure qui est ré-empruntée par le rift Cénozoïque (faille Eyasi). A Manyara, les séismes sont remarquablement profonds (~20-35 km) et révèlent un décrochement sénestre sur un plan NE-SW. Ils illustrent le développement du rift vers le sud/sud-ouest sur la branche centrale Natron-Manyara-Balangida, au contact du craton tanzanien en profondeur. La contrainte principale minimum calculée dans la zone est orientée WNW-ESE et le régime tectonique local associé est transtensif. Il est fort probable que des fluides soient associés au déclenchement de cette séquence sismique profonde et de longue durée. L'influence de l'héritage structural dans l'expression des processus magmatique et tectonique accommodant la déformation s'observe aussi à l'échelle lithosphérique, par le biais de l'anisotropie sismique. Nos résultats soulignent 3 points majeurs: (1) les structures lithosphériques héritées (contrastes rhéologiques, fabriques crustale et mantellique) exercent un contrôle majeur sur la localisation et l'expression précoce du rifting continental; (2) la distribution des séismes en profondeur apparaît être un bon révélateur des propriétés rhéologiques de la croûte (transition fragile-ductile); et (3) dès le stade du rift immature (où la croûte est peu étirée), les processus magmatiques semblent jouer un rôle prépondérant dans l'accommodation de la déformation, en étroite interaction avec les processus tectoniques.
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Doubre, Cécile. « Structure et mécanismes des segments de rift volcano-tectoniques : études de rifts anciens (Ecosse, Islande) et d'un rift actif (Asal-Ghoubbet) ». Le Mans, 2004. http://www.theses.fr/2004LEMA1002.
Texte intégralRésumé :
Cette étude repose sur des observations structurales dans des segments de rift anciens (Skye et Sud-Est de l'Islande) et sur une expérience de sismologie dans le rift actif d'Asal, Djibouti. La confrontation de ces résultats rend compte du fonctionnement d'un segment de rift à partir des déformations finies et instantanées et de préciser son évolution sur différentes échelles de temps. Les études structurales basées sur la photogrammétrie dans les rifts anciens soulignent le rôle majeur du centre magmatique et de son activité sur la localisation et l'initiation des déformations tectoniques extensives. Les mécanismes au foyer et une analyse spatio-temporelle des séismes localisés dans le rift d'Asal montrent que la sismicité témoigne d'une activité tectonique relative aux failles majeures du rift, mais aussi magmatique, relative à la dynamique du réservoir mis en évidence par tomographie sismiqueThis study relies upon structural observations withl'n anciens rift segments (Skye and Southeastern Iceland) and upon a seismology experiment in the active Asal rift (Djibouti). Comparison of the resulis conveys the operating mechanisms of a rift segment from ils finite and instantaneous deformation, and clarifies ils évolution over différent time scales. The structural studies based on photogrammetry in the old rifts underline the major rote of the magi-natic center and ils activily on the localisation and the initiation of the extensive lectonic deformation. The focal mechanisms and the space-lime évolution of the localized earthquakes suggest that a fraction of seismicity comes from major rift faulis, whereas another one does from the Inagmatic réservoir activily
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Albaric, Julie. « Relations entre déformation active, rhéologie et magmatisme dans un rift continental : étude sismologique de la divergence nord-tanzanienne, rift est-africain ». Brest, 2009. https://tel.archives-ouvertes.fr/tel-00495984v2.
Texte intégralRésumé :
Cette étude vise à mieux comprendre le rôle respectif et l’interaction entre les différents mécanismes qui contrôlent l’initiation et le développement des rifts (magmatisme, faille, fabrique lithosphérique, rhéologie). Pour ce faire, le premier réseau local de 35 stations sismologiques a été déployé dans la Divergence Nord-Tanzanienne, la portion la plus jeune du Rift Est-Africain, pendant une période de six mois. Les signaux des séismes proches et lointains sont utilisés comme indicateurs de l’histogénèse, de la résistance crustale, de champs de déformation et de contraintes, et renseignent aussi sur la structure et l’anisotropie lithosphérique. Une crise sismique enregistrée au Nord de la Tanzanie (Gelai) illustre la co-existence de processus magmatiques et tectoniques, avec mise en place d’un dyke et e comportement à la fois asismique (glissement lent) et sismique (séisme de magnitude Mw 5. 9) de failles normales. La crise de Gelai indique le rôle majeur et auparavant Insoupçonné des processus asismiques dans l’accommodation de la déformation. Des séismes crustaux remarquablement profonds ont été observés plus au sud, dans la région du Lac Manyara. La sismicité de Manyara est associée à des glissements en faille normale et en décrochement probablement déclenchés par des fluides en base de croûte. L’ensemble de la sismicité enregistrée dans la DNT indique l’influence de l’héritage structural, ce qui s’observe aussi à l’échelle lithosphérique, par le biais de l’anisotropie sismiqueThe objective of this study is to better understand the role and the interaction between the different mechanisms that control rift initiation and development (magmatism, fauting, lithospheric fabric, rheology). To this end, a local seismic network has been deployed for the first time in the youngest part of the East African Rift, the North Tanzanian Divergence, for six months. Seismic signal was analyzed to characterize earthquake triggering mechanisms, crustal strength, strain and stress field, and seismic anisotropy. A seismic crisis occurred in North Tanzania (Gelai) involving dyking, seismic and aseismic slip. The Gelai crisis highlights the potential major role of aseismic processes in strain accommodation. Deep crustal earthquakes were recorded in the Lake Manyara region, Manyara seismicity is associated with strike-slip and normal faulting most Iikely triggered by fluids at depth. The influence of structural inheritance on rifting is indicated at lithospheric scale by seismicity and seismic anisotropy