991 resultados para Plateau zokor ( Myospalax bailey)
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La prsente publication s'intresse un nouveau domaine de recherche des politiques environnementales. Elle se propose de thoriser et d'analyser le sous-sol comme une ressource naturelle potentiellement menace. Le sous-sol suisse est depuis quelques annes l'objet d'une forte intensification des demandes d'utilisation. Une pression dmographique croissante s'exerce sur le Plateau, entrainant une augmentation du nombre d'infrastructures. Paralllement, l'accroissement gnral de la valeur des terrains dans les villes pousse une utilisation accrue de l'espace souterrain. Les progrs techniques rendent possible l'implantation d'infrastructures dans presque tous les contextes gologique. Enfin, la volont politique et sociale de voir certains ouvrages ou substances, comme les dchets nuclaires, enterrs peut s'avrer dterminante. L'approche thorique privilgie dans cette tude pour aborder le thme de la gestion durable de l'exploitation du sous-sol est celle, dveloppe l'IDHEAP, des Rgimes institutionnels de ressources (RIR). Cette dmarche se caractrise par sa volont d'aborder la gestion d'une ressource de manire globale, en faisant fi des dcoupages territoriaux et institutionnels. Les rsultats de l'analyse des juridictions cantonales et fdrales indiquent un risque clair de surexploitation de la ressource. En cause, le flou qui rgne autour de la dfinition des droits de proprit du sous-sol et la faible coordination des politiques publiques concernes. L'tude se conclut sur une mise en perspective des possibilits de rgulation qui s'offrent aux dcideurs politiques, s'ils dcident de prendre en charge le risque de surexploitation du sous-sol.
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Rsum Scientific:Ptrologie et Gochimie du Complexe Plutonique de Chaltn et les consquences pour l'volution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocneLe sujet de cette thse est le Complexe Plutonique de Chaltn (CHPC), situ la frontire entre le Chili et l'Argentine, en Patagonie (4915'S). Ce complexe s'est mis en place au dbut du Miocne, dans un contexte de changements tectoniques importants. La gomtrie et la vitesse de migration des plaques en Patagonie a t modifie suite l'ouverture de la plaque Farallon il y a 25Ma (Pardo-Casas and Molnar 1987) et la subduction de la ride active du Chili sous la plaque sud-amricaine il y a 14Ma (Cande and Leslie 1986). Les effets de cette reconfiguration tectonique sur la morphologie et le magmatisme de la plaque suprieure sont encore sujets discussion. Dans ce contexte, un groupe d'intrusions miocnes - telle que le CHPC - est particulirement intriguant, car en position transitionnelle entre le batholithe patagonien et l'arc volcanique cnozoque et rcent l'ouest, et les laves de plateau de Patagonie l'est (Fig. 1). A cause de leur position tectonique transitoire, ces plutons isols hors du batholithe reprsentent un endroit cl pour comprendre les interactions entre la tectonique large chelle et le magmatisme en Patagonie. Ici, je prsente de nouvelles donnes de terrain, petrologiques, gochimiques et gochronologiques dans le but de caractriser la nature du CHPC, qui tait largement inconnu avant cette tude, dans le but de tester l'hypothse de migration de l'arc et erosion par subduction.Les rsultats de l'investigation gochimique (chapitre 2) montrent que le CHPC n'est qu'un exemple parmi les plutons isols d'arrire arc ave une composition calco-alcaline caractristique, c--d une signature d'arc. La plupart de ces plutons isols ont une composition alcaline. Le CHPC, contrairement, a une signature calco-alcaline avec Κ intermdiaire, tel que le batholithe patagonien et la plupart des roches volcaniques quaternaires lies l'arc le long des Andes.De nouvelles donnes gochronologiques U-Pb de haute prcision sur des zircons, acquis par TIMS, sur le CHPC donnent des ges entre 17.0 et 16.4Ma. Les ges absolus sont en accord avec la squence intrusive dduite des relations de terrain (chapitre 1). Ces donnes sont les premires contraintes d'ge U-Pb sur le CHPC. Elles montrent clairement que l'histoire magmatique du CHPC n'a pas de lien direct avec la subduction de la ride cette latitude (Cande and Leslie 1986), car le complexe est au moins 6Ma plus ancien.Une comparaison en profondeur avec les autres intrusions d'ge Miocne en Patagonie rvlent - pour la premire fois - une volution temporelle intressante. Il y a une tendance E-W distincte au magmatisme calco-alcalin entre 20-16Ma avec une diminution de l'ge vers l'est - le CHPC est l'expression la plus orientale de cette tendance. Je suggre que la relation espace-temps reflte une migration vers l'est (vers le continent) de l'arc magmatique. Je propose que le facteur principal contrlant cette migration est la subduction rapide suite la reconfiguration de la vitesse des plaques tectoniques aprs l'ouverture la plaque Farallon ( ~26Ma) qui rsulterait en une dformation importante ainsi qu' des taux levs d'rosion dans la fosse de subduction.Les rapports d'isotopes radiogniques (Pb, Sr, Nd) levs, une signature 6018 basse et un rapport Th/La lev sont des paramtres distinctifs pour les roches mafiques du CHPC. Le modle isotopique prsent (chapitre 2) suggre que cette signature reflte une contamination de la source, dans le coin de manteau, plutt qu'une contamination crustale. La signature des lments en trace du CHPC indiquent que le coin de manteau a t contamin par des composs terrignes, le plus vraisemblablement par des sdiments palozoques.Les travaux de terrain, la ptrographie et la gothermobaromtrie ont t utiliss dans le but de comprendre l'histoire interne du CHPC (chapitre 3). Ces donnes suggrent deux niveaux distincts de cristallisation : l'un dans la crote moyenne (6 4.5kbar) et l'autre un niveau peu profond (3.5 2kbar). La modlisation isotopique AFC de la contamination crustale indique des taux variables d'assimilation, qui ne sont pas corrls avec le degr de diffrenciation. Cela suggre que diffrents volumes de magma se sont diffrencis en profondeur, de faon indpendante. Cela implique que le CHPC se serait forms en plusieurs puises de magmas provenant d'au moins trois sources diffrentes. Les textures des granodiorites et des granites indiquent des teneurs leves en cristaux avant la mise en place et, par consquent, des tempratures d'emplacement faibles. Les observations de terrain montrent que les roches mafiques sont dformes, alors que ce n'est pas le cas pour les granodiorites et granites (plus jeunes). La dformation des roches mafiques est encore sujet de recherche, afin de savoir si elle est lie la dformation rgionale en rgime compressif ou l'emplacement lui-mme. Cependant, la mise en place de grand volume de magma felsique riche en cristaux suggre un rgime d'extension.Scientific Abstract:Petrology and chemistry of the Chaltn Plutonic Complex and implications on the magmatic and tectonic evolution of the Southernmost Andes (Patagonia) during the MioceneThe subject of this thesis is the Chaltn Plutonic Complex (CHPC) located at the frontier between Chile and Argentina in Patagonia (at 49 15 'Southern latitude). This complex intruded during early Miocene in a context of major tectonics changes. The plate geometry of Patagonia has been modified by changes in the plate motions after the break up of the Faralln plate at 25Ma (Pardo-Casas and Molnar 1987) and by the subduction of the Chile spreading Ridge beneath South-America at 14 Ma (Cande and Leslie 1986). The effects of this tectonic setting on the morphology and the magmatism of the overriding plate are a matter of on-going discussion. Particularly intriguing in this context is a group of isolated Miocene intrusions - like the CHPC - which are located in a transitional position between the Patagonian Batholith and the Cenozoic and Recent volcanic arc in the West, and the Patagonian plateau lavas in the East (Fig. 1). Due to their transient tectonic position these isolated plutons outside the batholith represent a key to understanding the interaction between global-scale tectonics and magmatism in Patagonia. Here, I present new field, penological, geochemical and geochronological data to characterize the nature of the CHPC, which was largely unknown before this study, in order to test the hypothesis of time- transgressive magmatism.The results of the geochemical investigation (Chapter 2) show that the CHPC is only one among these isolated back-arc plutons with a characteristic calc-alkaline composition, i.e. arc signature. Most of these isolated intrusives have an alkaline character. The CHPC, in contrast, has a medium Κ calc-alkaline signature, like the Patagonian batholith and most of the Quaternary arc-related volcanic rocks along the Andes.New high precision TIMS U-Pb zircon dating of the CHPC yield ages between 17.0 to 16.4 Ma. The absolute ages support the sequence of intrusion relations established in the field (Chapter 1). These data are the first U-Pb age constraints on the CHPC, and clearly show that the magmatic history of CHPC has no direct link to the subduction of the ridge, since this complex is at least 6 Ma older than the time of collision of the Chile ridge at this latitude (Cande and Leslie 1986).An in-depth comparison with other intrusion of Miocene age in Patagonia reveals - for the first time - an interesting temporal pattern. There is a distinct E-W trend of calc-alkaline magmatism between 20-16 Ma with the younging of ages in the East - the CHPC is the easternmost expression of this trend. I suggest that this time-space relation reflects an eastward (landward) migration of the magmatic arc. I propose that main factor controlling this migration is the fast rates of subduction after the major reconfigurations of the plate tectonic motions after the break up of the Faralln Plate (at -26 ) resulting in strong deformation and high rates of subduction erosion.High radiogenic isotope ratios (Pb, Sr, Nd) ratios, low 5018 signature and high Th/La ratios in mafic rocks are distinctive features of the CHPC. The presented isotopic models (Chapter 2) suggest that this signature reflects source contamination of the mantle wedge rather than crustal contamination. The trace element signature of the CHPC indicates that the mantle wedge was contaminated with a terrigenous component, most likely from Paleozoic sediments.Fieldwork, petrography and geothermobarometry were used to further unravel the internal history of the CHPC (Chapter 3). These data suggest two main levels of crystallization: one a mid crustal levels (6 to 4.5 kbar) and other a shallow level (3.5 to 2 kbar). Isotopic AFC modeling of crustal contamination indicate variable rates of assimilation, which are not correlated with the degree of differentiation. This suggests that different batches of magma differentiate independently at depths. This implies that the CHPC would have formed by several pulses of magmas from at least 3 different sources. Textures of granodiorites and granites indicate a high content of crystals previous to the emplacement and consequently low emplacement temperatures. Field observations show that the mafic rocks are deformed, whereas the (younger) granodiorites and granites are not. It is still subject of investigation whether the deformation of the mafic rocks is related to regional deformation during a compressional regime or to the emplacement it self. However, the emplacement of huge amount of crystal rich felsic magmas suggests an extensional regime.Rsum Grand PublicPtrologie et Gochimie du Complexe Plutonique de Chaltn et les consquences pour l'volution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocneLe Complexe Plutonique de Chaltn (CHPC) est un massif montagneux situ 49S la frontire entre le Chili et l'Argentine, en Patagonie (rgion la plus au sud de l'Amrique du Sud). Il est compos de montagnes qui peuvent atteindre plus de 3000 mtres d'altitude, telles que le Cerro Fitz Roy (3400m) et le Cerro Torre (3100m). Ces montagnes sont composes de roches plutoniques, c.--d. des magmas qui se sont refroidis et ont cristalliss sous la surface terrestre.La composition chimique de ces roches montre que les magmas, qui ont form ce complexe plutonique, font partie d'un volcanisme d'arc. Celui-ci se forme lorsqu'une plaque ocanique plonge sous une plaque continentale. Les gologues appellent ce processus subduction . Dans un tel scnario, le manteau terrestre, qui se fait prendre entre ces deux plaques, fond pour former ainsi du magma. Ce magma remonte travers la plaque continentale vers la surface. Si celui-ci atteint la surface, il forme les roches volcaniques, comme par exemple des laves. S'il n'atteint pas la surface, le magma se refroidit pour former finalement les roches plutoniques.Le long de la marge ouest d'Amrique du Sud, la plaque Nazca - qui se situe au sud-est de la plaque ocanique pacifique - passe en dessous de la plaque d'Amrique du Sud. La bordure ouest du sud de la plaque sud-amricaine a galement t affecte par d'autres processus tectoniques, tels que des changements dramatiques dans les dplacements de plaques (il y a 25Ma) et la collision de la ride du Chili (depuis 15 Ma jusqu' aujourd'hui). Ces caractristiques tectoniques et magmatiques font de cette rgion un haut lieu pour les gologues. La plaque Nazca, s'est forme suite l'ouverture d'une plaque ocanique plus ancienne, il y a 25Ma. Cette ouverture est lie aux vitesses de subduction les plus rapides jamais connues. La ride du Chili est l'endroit o le sol de l'Ocan Pacifique s'ouvre, formant deux plaques ocaniques : les plaques Nazca et Antarctique. La ride du Chili subducte sous la plaque sud-amricaine depuis 15Ma, en association avec la formation de grands volumes de magma ainsi que des changements morphologiques importants. La question de savoir lequel de ces changements tectoniques globaux affecte la gologie et la gographie de Patagonie a t, et est encore, discute pendant de nombreuses annes. De nombreux chercheurs suggrent que la plupart des caractristiques morphologiques et magmatiques en Patagonie sont lis la subduction de la ride du Chili, mais cette suggestion est encore dbattue comme le montre notre tude.Le batholithe de Patagonie du sud (SPB) est un norme massif compos de roches plutoniques et il s'tend tout au long de la cte ouest de Patagonie (au sud de 47S). Ces roches correspondent certainement aux racines d'un ancien arc volcanique, qui a t soulev et rod. Le CHPC, ainsi que d'autres petites intrusions dans la rgion, se situe dans une position exotique, 100km l'est du SPB. Certains chercheurs suggrent que ces intrusions pourraient tre lies la subduction de la ride du Chili.Afin de dbattre de cette problmatique, nous avons utilis diffrentes mthodes gochronologiques pour dterminer l'ge du CHPC et le comparer (a) l'ge des roches intrusives similaires du SPB et (b) l'ge de la collision de la ride du Chili. Dans ce travail, nous prouvons que le CHPC s'est form au moins 7Ma avant la collision avec la ride du Chili. Sur la base des ges du CHPC et de la composition chimique de ses roches et minraux, nous proposons que le CHPC fait partie d'un arc volcanique ancien. La migration de l'arc volcanique plus profondment dans le continent rsulte de la grande vitesse de subduction entre 25 et lOMa. Des caractristiques videntes pour un tel processus - telles qu'une dformation importante et une vitesse d'rosion leve - peuvent tre rencontres tout au long de la bordure ouest de l'Amrique du sud.
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Abstact : Pollinic contribution to a Pleistocene study of the Lake Geneva region (Switzerland) Palaeoenvironment of the last 800,000 years. Although the "Plateau Romand" (tableland of French-speaking Switzerland) has been marked by the repetitive action of different Quaternary glacial thrusts, numerous preserved outcrops here and there, thanks to favourable topographical conditions, provide sufficient pollinic content to reconstitute the significant botanical fluctuations and allow bio- and chrono-stratigraphical correlations with the long European sequences. The present study examines around ten Pleistocene deposits rich in pollens, whose presumed ages cover a range of 800,000 years. - The Early and Early-Middle Pleistocene are examined at Ecoteaux (VD), undeniably the oldest site in this study. The "Lower Formation of Ecoteaux", whose low pollinic content reveals an environment of the cold desert type, shows an inverse palaeomagnetic remanence. An age earlier than 780,000 years BP (Matuyama period or earlier) is proposed. The "Upper Formation of Ecoteaux" contains over eight major fluctuations in the vegetal covering, of which at least four temporal phases and one climatic optimum. The presence of botanical genera, relics of the Tertiary in particular Pterocarya and Carya, associated with the vegetal dynamic made up of short oscillations, contrives to link this formation to the Cromerian Complex. The thermomeres recorded could correspond to one or several interglacial periods from Middle Pleistocene. Possible correlations with marine isotopic stages 15, 17 and 19 are discussed. - The Middle and Late Pleistocene is approached through the sediments of Onnens (VD), Creux d'Enfer (FR), Port-Valais (VS), La Dnriaz (VD) and Cortaillod (NE). Each site provides a temperate interglacial flora, whose pollinic content is evaluated according to the different conceivable bio-stratigraphic correlations. - Finally the Wrm is studied thanks to the outcrop of Marly (FR), together with the excavations at Villars-sous-Yens (VD), Versoix (GE) and Ollon (VD). Together, these observations tend to show that the west of the Swiss Plateau is a zone of transition between the meridian vegetation of the lower Rhone valley and that of beyond the Jura. At the outlet of the Rhone glacier, and on the borders of the prealpine and Jurassian glaciers, the region is situated at the crossroads of post-glacial botanical migrations, between the major axis of the Rhone valley and the Eastern refuge zones; this situation confers particular importance on it. Although believed to be deeply scraped by ice, one notices today that the "Plateau Romand" harbours overtwenty interglacial and interstadial sites. The abrasive action of the Rhone glacier has thus been more modest than previously estimated. The effective extension of glacial tongues, together with atmospheric circulation, are doubtless varying from one interglacial to another. Finally, the speeds of glacial movements, and the unbelievable vegetal vitality, are important parameters, capable of leading to deposits, very early enriched in pollens. RSUMS : Contribution pollinique l'tude du Plistocne de la rgion lmanique (Suisse) - Paloenvironnement des derniers 800'000 ans Bien que le Plateau romand soit marqu par l'action rptitive des diffrentes pousses glaciaires quaternaires, de nombreux affleurements prservs a et l, la faveur de conditions topographiques favorables, livrent un contenu pollinique suffisant pour reconstituer des fluctuations botaniques significatives et autoriser des corrlations bioet chronostratigraphiques avec les longues squences europennes. Le prsent travail tudie une dizaine de dpts plistocnes riches en pollens, dont les ges prsums balaient un ventail de plus de 800'000 ans. - Le Plistocne Ancien et Moyen infrieur, sont examins Ecoteaux (VD); indniablement le site le plus ancien de cette tude. La "Formation infrieure d'Ecoteaux", dont le maigre contenu pollinique traduit un environnement de type dsertique froid, prsente une rmanence magntique inverse. Un ge antrieur 780'000 ans BP (priode de Matuyama ou antrieure) est propos. La "Formation suprieure d'Ecoteaux" comprend plus de huit fluctuations majeures du couvert vgtal, parmi lesquelles on compte au moins quatre pisodes temprs et un optimum climatique. La prsence de genres botaniques reliques du Tertiaire, en particulier Pterocarya et Carya, associe la dynamique vgtale faite de courtes oscillations, concourent lier cette formation au Complexe Cromrien. Les thermomres enregistres pourraient correspondre un- ou plusieurs interglaciaires du Plistocne moyen. Les corrlations possibles avec les stades isotopiques marins, MIS 15, 17 et 19 sont discutes. - Le Plistocne Moyen et Rcent est abord travers les sdiments d'Onnens (VD), du Creux d'Enfer (FR), de Port-Valais (VS), de La Dnriaz (VD) et de Cortaillod (NE). Chaque site livre une flore tempre interglaciaire, dont le contenu pollinique est valu en fonction des diffrentes corrlations bio-stratigraphiques envisageables. - Enfin le Wrm est tudi grce l'affleurement de Marly (FR), accompagn des forages de Villars-sous-Yens (VD), Versoix (GE) et Ollon (VD). L'ensemble de ces observations tend montrer que l'ouest du Plateau suisse est une zone charnire entre la vgtation mridionale de la basse valle du Rhne et celle d'au-del du Jura. Au dbouch du glacier du Rhne et aux confins des glaciers pralpins et jurassiens, cette rgion est situe au carrefour des migrations botaniques post-glaciaires, entre l'axe majeur de la valle du Rhne et les zones refuges de l'Est. Cette situation lui confre une importance toute particulire. Alors qu'on pensait le Plateau romand profondment rabot par les glaces, on constate aujourd'hui qu'il recle plus d'une vingtaine de sites interglaciaires et interstadiaires. L'action abrasive du glacier rhodanien a donc t plus modeste qu'envisage jusqu'ici. L'extension effective des langues glaciaires, tout comme la circulation atmosphrique, diffrent sans doute d'un interglaciaire l'autre. Enfin la vitesse des mouvements glaciaires et l'incroyable vitalit vgtale sont des paramtres importants, susceptibles d'avoir entran des dpts, trs prcocement enrichis en pollens.
Total knee arthroplasty - a clinical and numerical study of the micromovements of the tibial implant
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Introduction The importance of the micromovements in the mechanism of aseptic loosening is clinically difficult to evaluate. To complete the analysis of a series of total knee arthroplasties (TKA), we used a tridimensional numerical model to study the micromovements of the tibial implant.Material and Methods Fifty one patients (with 57 cemented Porous Coated Anatomic TKAs) were reviewed (mean follow-up 4.5 year). Radiolucency at the tibial bone-cement interface was sought on the AP radiographs and divided in 7 areas. The distribution of the radiolucency was then correlated with the axis of the lower limb as measured on the orthoradiograms.The tridimensional numerical model is based on the finite element method. It allowed the measurement of the cemented prosthetic tibial implant's displacements and the microvements generated at bone-ciment interface. A total load (2000 Newton) was applied at first vertically and asymetrically on the tibial plateau, thereby simulating an axial deviation of the lower limbs. The vector's posterior inclination then permitted the addition of a tangential component to the axial load. This type of effort is generated by complex biomechanical phenomena such as knee flexion.Results 81 per cent of the 57 knees had a radiolucent line of at least 1 mm, at one or more of the tibial cement-epiphysis jonctional areas. The distribution of these lucent lines showed that they came out more frequently at the periphery of the implant. The lucent lines appeared most often under the unloaded margin of the tibial plateau, when axial deviation of lower limbs was present.Numerical simulations showed that asymetrical loading on the tibial plateau induced a subsidence of the loaded margin (0-100 microns) and lifting off at the opposite border (0-70 microns). The postero-anterior tangential component induced an anterior displacement of the tibial implant (160-220 microns), and horizontal micromovements with non homogenous distribution at the bone-ciment interface (28-54 microns).Discussion Comparison of clinical and numerical results showed a relation between the development of radiolucent lines and the unloading of the tibial implant's margin. The deleterious effect of lower limbs' axial deviation is thereby proven. The irregular distribution of lucent lines under the tibial plateau was similar of the micromovements' repartition at the bone-cement interface when tangential forces were present. A causative relation between the two phenomenaes could not however be established.Numerical simulation is a truly useful method of study; it permits to calculate micromovements which are relative, non homogenous and of very low amplitude. However, comparative clinical studies remain as essential to ensure the credibility of results.
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Deformation of the Circum-Rhodope Belt Mesozoic (Middle Triassic to earliest Lower Cretaceous) low-grade schists underneath an arc-related ophiolitic magmatic suite and associated sedimentary successions in the eastern Rhodope-Thrace region occurred as a two-episode tectonic process: (i) Late Jurassic deformation of arc to margin units resulting from the eastern Rhodope-Evros arc-Rhodope terrane continental margin collision and accretion to that margin, and (ii) Middle Eocene deformation related to the Tertiary crustal extension and final collision resulting in the closure of the Vardar ocean south of the Rhodope terrane. The first deformational event D-1 is expressed by Late Jurassic NW-N vergent fold generations and the main and subsidiary planar-linear structures. Although overprinting, these structural elements depict uniform bulk north-directed thrust kinematics and are geometrically compatible with the increments of progressive deformation that develops in same greenschist-facies metamorphic grade. It followed the Early-Middle Jurassic magmatic evolution of the eastern Rhodope-Evros arc established on the upper plate of the southward subducting Maliac-Meliata oceanic lithosphere that established the Vardar Ocean in a supra-subduction back-arc setting. This first event resulted in the thrust-related tectonic emplacement of the Mesozoic schists in a supra-crustal level onto the Rhodope continental margin. This Late Jurassic-Early Cretaceous tectonic event related to N-vergent Balkan orogeny is well-constrained by geochronological data and traced at a regional-scale within distinct units of the Carpatho-Balkan Belt. Following subduction reversal towards the north whereby the Vardar Ocean was subducted beneath the Rhodope margin by latest Cretaceous times, the low-grade schists aquired a new position in the upper plate, and hence, the Mesozoic schists are lacking the Cretaceous S-directed tectono-metamorphic episode whose effects are widespread in the underlying high-grade basement. The subduction of the remnant Vardar Ocean located behind the colliding arc since the middle Cretaceous was responsible for its ultimate closure, Early Tertiary collision with the Pelagonian block and extension in the region caused the extensional collapse related to the second deformational event D-2. This extensional episode was experienced passively by the Mesozoic schists located in the hanging wall of the extensional detachments in Eocene times. It resulted in NE-SW oriented open folds representing corrugation antiforms of the extensional detachment surfaces, brittle faulting and burial history beneath thick Eocene sediments as indicated by 42.1-39.7 Ma Ar-40/Ar-39 mica plateau ages obtained in the study. The results provide structural constraints for the involvement components of Jurassic paleo-subduction zone in a Late Jurassic arc-continental margin collisional history that contributed to accretion-related crustal growth of the Rhodope terrane. (C) 2011 Elsevier Ltd. All rights reserved.
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During ODP Leg 123, abundant and well-preserved Neocomian radiolarians were recovered at Site 765 (Argo Abyssal Plain) and Site 766 (lower Exmouth Plateau). Assemblages are characterized by the numerical dominance of a small number of non-tethyan forms and by the scarcity of tethyan taxa. Remarkable contrasts exist between radiolarian assemblages extracted from claystones of Site 765 and reexamined DSDP Site 26 1, and faunas recovered from radiolarian sand layers, only found at Site 765. Clay faunas are unusual in their low diversity of apparently ecologically tolerant (or solution resistant?), ubiquist species, whereas sand faunas are dominated by non-tethyan taxa. Comparisons with Sites 766 and 26 1, as well as sedimentological observations, lead to the conclusion that this faunal contrast resulted from a difference in provenance, rather than from hydraulic sorting or selective dissolution. The ranges of 27 tethyan taxa from Site 765 were compared to the tethyan radiolarian zonation by Jud (1992) by means of the Unitary Associations Method. This calculation allows to directly date the Site 765 assemblages and to estimate the amount of truncation of ranges for tethyan taxa. Over 70% of the already few tethyan species of Site 765, have truncated ranges during the Valanginian-Hauterivian. Radiolarian assemblages recovered from claystones at Sites 765 and 261 in the Argo Basin apparently reflect restricted oceanic conditions during the latest Jurassic-Barremian. Neither sedimentary facies nor faunal associations bear any resemblance to what we know from typical tethyan sequences. We conclude that the Argo Basin was paleoceanographically separated from the Tethys during the Late Jurassic and part of the Early Cretaceous by its position at higher paleolatitudes and/or by enclosing land masses. Assemblages recovered from radiolarian sand layers are dominated by non-tethyan species that are interpreted as circumantarctic. Their first appearance in the late Berriasian-early Valanginian predates the oceanization of the Indo-Australian breakup (M11, late Valanginian), but coincides with a sharp increase in margin-derived pelagic turbidites. The Indo-Australian rift zone and the adjacent margins must have been submerged deeply enough to allow an intermittent influx of circumantarctic cold water into the Argo Basin, creating increased bottom current activity. Cold-water radiolarians carried into the Argo Basin upwelled along the margin, died, and accumulated in radiolarite layers due to winnowing by bottom currents. High rates of faunal change and the sharp increase of bottom current activity are thought to be synchronous with possible pronounced late Berriasian-early Valanginian lowstands in sea level. Hypothetically, both phenomena might have been.caused by a tendency to glaciation on the Antarctic-Australian continent, which was for the first time isolated from the rest of Gondwana by oceanic seaways as a result of Jurassic-Early Cretaceous sea-floor spreading. The absence of most typical tethyan radiolarian species during the Valanginian-Hauterivian is interpreted as reflecting a time of strong influx of circumantarctic cold water following oceanization (M11) and rapid spreading between Southeast India and West Australia. The reappearance and gradual abundance/diversity increase of tethyan taxa, along with the still dominant circumantarctic species are thought to result from overall more equitable climatic conditions during the Barremian-early Aptian and from the establishment of an oceanic connection with the Tethys Ocean during the early Aptian.
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Genotypic and phenotypic tolerance was studied in penicillin treatment of experimental endocarditis due to nontolerant and tolerant Streptococcus gordonii and to their backcross transformants. The organisms were matched for in vitro and in vivo growth rates. Rats with aortic endocarditis were treated for 3 or 5 days, starting 12, 24, or 48 h after inoculation. When started at 12 h, during fast intravegetation growth, 3 days of treatment cured 80% of the nontolerant parent compared with <30% of the tolerant derivative (P < .005). When started at 24 or 48 h and if intravegetation growth had reached a plateau, 3 days of treatment failed against both bacteria. However, a significant difference between the 2 organisms was restored when treatment was extended to 5 days. Thus, genotypic tolerance conferred a survival advantage in both fast- and slow-growing bacteria, demonstrating that the in vitro-defined tolerant phenotype also carried the risk of treatment failure in vivo.
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BACKGROUND: RalA and RalB are multifuntional GTPases involved in a variety of cellular processes including proliferation, oncogenic transformation and membrane trafficking. Here we investigated the mechanisms leading to activation of Ral proteins in pancreatic beta-cells and analyzed the impact on different steps of the insulin-secretory process. METHODOLOGY/PRINCIPAL FINDINGS: We found that RalA is the predominant isoform expressed in pancreatic islets and insulin-secreting cell lines. Silencing of this GTPase in INS-1E cells by RNA interference led to a decrease in secretagogue-induced insulin release. Real-time measurements by fluorescence resonance energy transfer revealed that RalA activation in response to secretagogues occurs within 3-5 min and reaches a plateau after 10-15 min. The activation of the GTPase is triggered by increases in intracellular Ca2+ and cAMP and is prevented by the L-type voltage-gated Ca2+ channel blocker Nifedipine and by the protein kinase A inhibitor H89. Defective insulin release in cells lacking RalA is associated with a decrease in the secretory granules docked at the plasma membrane detected by Total Internal Reflection Fluorescence microscopy and with a strong impairment in Phospholipase D1 activation in response to secretagogues. RalA was found to be activated by RalGDS and to be severely hampered upon silencing of this GDP/GTP exchange factor. Accordingly, INS-1E cells lacking RalGDS displayed a reduction in hormone secretion induced by secretagogues and in the number of insulin-containing granules docked at the plasma membrane. CONCLUSIONS/SIGNIFICANCE: Taken together, our data indicate that RalA activation elicited by the exchange factor RalGDS in response to a rise in intracellular Ca2+ and cAMP controls hormone release from pancreatic beta-cell by coordinating the execution of different events in the secretory pathway.
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BACKGROUND: Acute exposure to high altitude stimulates free radical formation in lowlanders, yet whether this persists during chronic exposure in healthy, well-adapted and maladapted highlanders suffering from chronic mountain sickness (CMS) remains to be established. METHODS: Oxidative-nitrosative stress (as determined by the presence of the biomarkers ascorbate radical [A - ], via electron paramagnetic resonance spectroscopy, and nitrite [NO 2 2 ], via ozone-based chemiluminescence) was assessed in venous blood of 25 male highlanders in Bolivia living at 3,600 m with CMS (n 5 13, CMS 1 ) and without CMS (n 5 12, CMS 2 ). Twelve age- and activity-matched, healthy, male lowlanders were examined at sea level and during acute hypoxia. We also measured fl ow-mediated dilatation (FMD), arterial stiffness defined by augmentation index normalized for a heart rate of 75 beats/min (AIx-75), and carotid intima-media thickness (IMT). RESULTS: Compared with normoxic lowlanders, oxidative-nitrosative stress was moderately increased in the CMS 2 group ( P , .05), as indicated by elevated A - (3,191 457 arbitrary units [AU] vs 2,640 445 AU) and lower NO 2 2 (206 55 nM vs 420 128 nM), whereas vascular function remained preserved. This was comparable to that observed during acute hypoxia in lowlanders in whom vascular dysfunction is typically observed. In contrast, this response was markedly exaggerated in CMS 1 group (A - , 3,765 429 AU; NO 2 2 , 148 50 nM) compared with both the CMS 2 group and lowlanders ( P , .05). This was associated with systemic vascular dysfunction as indicated by lower ( P , .05 vs CMS 2 ) FMD (4.2% 0.7% vs 7.6% 1.7%) and increased AIx-75 (23% 8% vs 12% 7%) and carotid IMT (714 127 m M vs 588 94 m M). CONCLUSIONS: Healthy highlanders display a moderate, sustained elevation in oxidative-nitrosative stress that, unlike the equivalent increase evoked by acute hypoxia in healthy lowlanders, failed to affect vascular function. Its more marked elevation in patients with CMS may contribute to systemic vascular dysfunction.
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Protective adaptive immune responses rely on TCR-mediated recognition of Ag-derived peptides presented by self-MHC molecules. However, self-Ag (tumor)-specific TCRs are often of too low affinity to achieve best functionality. To precisely assess the relationship between TCR-peptide-MHC binding parameters and T cell function, we tested a panel of sequence-optimized HLA-A(*)0201/NY-ESO-1(157-165)-specific TCR variants with affinities lying within physiological boundaries to preserve antigenic specificity and avoid cross-reactivity, as well as two outliers (i.e., a very high- and a low-affinity TCR). Primary human CD8 T cells transduced with these TCRs demonstrated robust correlations between binding measurements of TCR affinity and avidity and the biological response of the T cells, such as TCR cell-surface clustering, intracellular signaling, proliferation, and target cell lysis. Strikingly, above a defined TCR-peptide-MHC affinity threshold (K(D) < approximately 5 muM), T cell function could not be further enhanced, revealing a plateau of maximal T cell function, compatible with the notion that multiple TCRs with slightly different affinities participate equally (codominantly) in immune responses. We propose that rational design of improved self-specific TCRs may not need to be optimized beyond a given affinity threshold to achieve both optimal T cell function and avoidance of the unpredictable risk of cross-reactivity.
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Micas are commonly used in Ar-40/Ar-39 thermochronological studies of variably deformed rocks yet the physical basis by which deformation may affect radiogenic argon retention in mica is poorly constrained. This study examines the relationship between deformation and deformation-induced microstructures on radiogenic argon retention in muscovite, A combination of furnace step-heating and high-spatial resolution in situ UV-laser ablation Ar-40/Ar-39 analyses are reported for deformed muscovites sampled from a granitic pegmatite vein within the Siviez-Mischabel Nappe, western Swiss Alps (Penninic domain, Brianconnais unit). The pegmatite forms part of the Variscan (similar to 350 Ma) Alpine basement and exhibits a prominent Alpine S-C fabric including numerous mica `fish' that developed under greenschist facies metamorphic conditions, during the dominant Tertiary Alpine tectonic phase of nappe emplacement. Furnace step-heating of milligram quantities of separated muscovite grains yields an Ar-40/Ar-39 age spectrum with two distinct staircase segments but without any statistical plateau, consistent with a previous study from the same area. A single (3 X 5 mm) muscovite porphyroclast (fish) was investigated by in situ UV-laser ablation. A histogram plot of 170 individual Ar-40/Ar-39 UV-laser ablation ages exhibit a range from 115 to 387 Ma with modes at approximately 340 and 260 Ma. A variogram statistical treatment of the (40)Ad/Ar-39 results reveals ages correlated with two directions; a highly correlated direction at 310 degrees and a lesser correlation at 0 degrees relative to the sense of shearing. Using the highly correlated direction a statistically generated (Kriging method) age contour map of the Ar-40/Ar-39 data reveals a series of elongated contours subparallel to the C-surfaces which where formed during Tertiary nappe emplacement. Similar data distributions and slightly younger apparent ages are recognized in a smaller mica fish. The observed intragrain age variations are interpreted to reflect the partial loss of radiogenic argon during Alpine (similar to 35 Ma) greenschist facies metamorphism. One-dirnensional diffusion modelling results are consistent with the idea that the zones of youngest apparent age represent incipient shear band development within the mica porphyroclasts, thus providing a network of fast diffusion pathways. During Alpine greenschist facies metamorphism the incipient shear bands enhanced the intragrain loss of radiogenic argon. The structurally controlled intragrain age variations observed in this investigation imply that deformation has a direct control on the effective length scale for argon diffusion, which is consistent with the heterogeneous nature of deformation. (C) 2001 Elsevier Science B.V. All rights reserved.
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BACKGROUND: Tenofovir (TDF) use has been associated with proximal renal tubulopathy, reduced calculated glomerular filtration rates (cGFR) and losses in bone mineral density. Bone resorption could result in a compensatory osteoblast activation indicated by an increase in serum alkaline phosphatase (sAP). A few small studies have reported a positive correlation between renal phosphate losses, increased bone turnover and sAP. METHODS: We analysed sAP dynamics in patients initiating (n = 657), reinitiating (n = 361) and discontinuing (n = 73) combined antiretroviral therapy with and without TDF and assessed correlations with clinical and epidemiological parameters. RESULTS: TDF use was associated with a significant increase of sAP from a median of 74 U/I (interquartile range 60-98) to a plateau of 99 U/I (82-123) after 6 months (P < 0.0001), with a prompt return to baseline upon TDF discontinuation. No change occurred in TDF-sparing regimes. Univariable and multivariable linear regression analyses revealed a positive correlation between sAP and TDF use (P < or = 0.003), but no correlation with baseline cGFR, TDF-related cGFR reduction, changes in serum alanine aminotransferase (sALT) or active hepatitis C. CONCLUSIONS: We document a highly significant association between TDF use and increased sAP in a large observational cohort. The lack of correlation between TDF use and sALT suggests that the increase in sAP is because of the bone isoenzyme and indicates stimulated bone turnover. This finding, together with published data on TDF-related renal phosphate losses, this finding raises concerns that TDF use could result in osteomalacia with a loss in bone mineral density at least in a subset of patients. This potentially severe long-term toxicity should be addressed in future studies.
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OBJECTIVES: The aim of this study was to evaluate right ventricular (RV) and left ventricular function and pulmonary circulation in chronic mountain sickness (CMS) patients with rest and stress echocardiography compared with healthy high-altitude (HA) dwellers. BACKGROUND: CMS or Monge's disease is defined by excessive erythrocytosis (hemoglobin >21 g/dl in males, 19 g/dl in females) and severe hypoxemia. In some cases, a moderate or severe increase in pulmonarypressure is present, suggesting a similar pathogenesis of pulmonary hypertension. METHODS: In La Paz (Bolivia, 3,600 m sea level), 46 CMS patients and 40 HA dwellers of similar age were evaluated at rest and during semisupine bicycle exercise. Pulmonary artery pressure (PAP), pulmonary vascular resistance, and cardiac function were estimated by Doppler echocardiography. RESULTS: Compared with HA dwellers, CMS patients showed RV dilation at rest (RV mid diameter: 365 mmvs. 32 4 mm, CMS vs. HA, p= 0.001) and reduced RV fractional area change both at rest (35 9% vs. 439%, p= 0.002) and during exercise (36 9% vs. 43 8%, CMS vs. HA, p= 0.005). The RV systolic longitudinal function (RV-S') decreased in CMS patients, whereas it increased in the control patients (p<0.0001) at peak stress. The RV end-systolic pressure-area relationship, a load independent surrogate of RV contractility, was similar in CMS patients and HA dwellers with a significant increase in systolic PAP and pulmonary vascular resistance in CMS patients (systolic PAP: 50 12 mm Hg vs. 38 8 mm Hg, CMS vs. HA, p < 0.0001; pulmonary vascular resistance: 2.9 1 mm Hg/min/l vs.2.2 1 mm Hg/min/l, p= 0.03). Both groups showed comparable systolic and diastolic left ventricular function both at rest and during stress. CONCLUSIONS: Comparable RV contractile reserve in CMS and HA suggests that the lower resting values of RV function in CMS may represent a physiological adaptation to chronic hypoxic conditions rather than impaired RV function. (Chronic Mountain Sickness, Systemic Vascular Function [CMS]; NCT01182792).
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The material studied comes from three of the several natural environments which still occur in Paran State. The samples were collected during the project PROFAUPAR, developed by Departamento de Zoologia, Universidade Federal do Paran. The selected sites were: Antonina (in the coastal plain), So Jos dos Pinhais (in the coastal mountain range) and Telmaco Borba (in the second plateau). During one year of the project, 2,106 specimens of Braconidae were collected with light trap. These wasps represented 21 subfamilies and 1,966 specimens were identified in 85 genera. Hormiinae, Rogadinae, Microgastrinae, Alysiinae, Doryctinae and Meteorinae were the most frequent subfamilies. Indices of diversity and evenness were used to discuss richness and dominance of genera in each locality. Statistical analyses indicated that the asymptote of actual genera richness have been approached only to Antonina and Telmaco Borba.
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A presente monografia inscreve-se no domnio temtico a sustentabilidade ambiental, tendo como ttulo Boas Prticas para um Ambiente Sustentvel. O objectivo principal consiste no levantamento do comportamento da populao residente na Regio do Planalto Leste, relativamente ao uso e explorao dos recursos naturais, tendo em vista a problemtica ambiental no contexto actual. Especificamente, quisemos saber que tipo de explorao dos recursos naturais disponveis na regio (Flora, Fauna), praticada pelos residentes do Planalto Leste, com base na Sustentabilidade e Insustentabilidade Ambiental. De acordo com os resultados obtidos, conclumos que essa explorao insustentvel, devido a factores do meio envolvente e propomos um estudo com maior profundidade para a implementao de Projectos de Educao e Sensibilizao Ambiental. This monograph inscribe above the theme, Best Practices for a Sustainable Environment, and the main objective is to survey the behavior of the resident population in the Eastern Plateau Region, relatively the use and exploration of natural resources, with a view to environmental issues within the current context. Specifically, we wanted to know what kind of exploration of natural resources available in the region (Flora, Fauna), is practiced by residents of the Eastern Plateau, and based on Environmental Sustainability and Unsustainability. According to the results, we conclude that this exploration is unsustainable on account of factors of surroundings and propose a study in deeper for implementation of projects Environmental Education and sensitization
