Monographie hydrologique du fleuve Gambie

Etude détaillée des conditions générales de l'écoulement du bilan de l'eau du bassin du fleuve Gambi

Whole-genome, deep pyrosequencing analysis of a duck influenza A virus evolution in swine cells.

We studied the sub-population level evolution of a duck influenza A virus isolate during passage in swine tracheal cells. The complete genomes of the A/mallard/Netherlands/10-Nmkt/1999 strain and its swine cell-passaged descendent were analysed by 454 pyrosequencing with coverage depth ranging from several hundred to several thousand reads at any point. This allowed characterization of defined minority sub-populations of gene segments 2, 3, 4, 5, 7, and 8 present in the original isolate. These minority sub-populations ranged between 9.5% (for segment 2) and 46% (for segment 4) of their respective gene segments in the parental stock. They were likely contributed by one or more viruses circulating within the same area, at the same period and in the same or a sympatric host species. The minority sub-populations of segments 3, 4, and 5 became extinct upon viral passage in swine cells, whereas the minority sub-populations of segments 2, 7 and 8 completely replaced their majority counterparts. The swine cell-passaged virus was therefore a three-segment reassortant and also harboured point mutations in segments 3 and 4. The passaged virus was more homogenous than the parental stock, with only 17 minority single nucleotide polymorphisms present above 5% frequency across the whole genome. Though limited here to one sample, this deep sequencing approach highlights the evolutionary versatility of influenza viruses whereby they exploit their genetic diversity, predilection for mixed infection and reassortment to adapt to a new host environmental niche.This work was supported by a grant from DEFRA and HEFCE under the Veterinary Training and Research Initiative to the Cambridge Infectious Diseases Consortium (VB, LT), BBSRC grants BB/H014306/1 and BB/G00479X/1 (LT), and the French Ministry of Agriculture, INRA and the French Région Midi-Pyrénées (GC, J-LG, VB).This is the accepted version of the original version available at: http://dx.doi.org/10.1016/j.meegid.2013.04.03

Hydrothermally-induced changes in mineralogy and magnetic properties of oxidized A-type granites

The changes in magnetic mineralogy due to the hydrothermal alteration of A-type granitic rocks have been thoroughly\ud investigated in samples fromthe granite of Tana (Corsica, France), and compared with other A-type granites:\ud Meruoca (NE Brazil), Bushveld (South Africa), Mount Scott (Wichita Mountains, Oklahoma, USA) and the\ud stratoid hypersolvus granites of Madagascar. The altered red-colored samples and their non-altered equivalents\ud were magnetically characterized by means of magnetic susceptibility measurements, hysteresis loops, remanent\ud coercivity spectra, and Lowrie test. It is shown that hydrothermalization in magnetite-bearing granites is related\ud to the formation of fine-grained magnetite and hematite, and to coeval depletion in the content of primary lowcoercive\ud coarse-grained magnetite. These mineralogical changes give typical rock magnetic signatures, namely\ud lower susceptibilitymagnitudes and anisotropy degrees, prolateAMS (anisotropy ofmagnetic susceptibility) fabrics\ud and increased coercivities. Optical microscopy and SEM (scanning electronic microscopy) images suggest\ud that the orientation of the secondary magnetic minerals is related to fluid-pathways and micro-fractures formed\ud during the hydrothermal event and therefore may be unrelated to magma emplacement and crystallization fabrics.\ud Changes inmagnetic mineralogy and grain-size distribution have also to be considered for any paleomagnetic\ud and iron isotope studies in granites.INSU-3F (Failles, fractures, flux) 2008 projec

Anisotropy of magnetic susceptibility of the Pyrenean granites

In this paper, we report on a compilation of more than 2200 sites (more than 10,000 individual measurements) where anisotropy of magnetic susceptibility (AMS) was studied in granites from the Variscan Pyrenees. The standardization and homogenization of this information has allowed us to produce three Main Maps that synthesize all the information related with the AMS of the Pyrenean granites. We also describe the problems found during the construction of the database (variable geo-positioning, different published information, etc.). The information derived from 21 granite bodies, the database, and the synthesis maps (magnetic susceptibility, Km, and the orientation of the magnetic foliation, plane perpendicular to k3, and of the magnetic lineation, k1) allow us to see for the first time a complete image of this important kinematic and petrographic indicator

Petrophysical characterization of non-magnetic granites; density and magnetic susceptibility relationships

In this work we establish reliable correlations between density and magnetic susceptibility in three paramagnetic granites from the Pyrenees. In total, 128 sites (310 density measurements and >2600 susceptibility ones) were studied in the Mont Louis-Andorra, Maladeta and Marimanha granitic plutons covering the main range of variability of magnetic susceptibility. Regressions were calculated for every granitic body and an integrated linear function was obtained for the entire dataset: ρ (kg/m3) = 2566 (kg/m3) + 0.541κ (10−6 S.I.) (R:0.97). This relationship is only valid in the paramagnetic domain, where iron is mostly fractioned in iron-bearing phyllosilicates and the occurrence of magnetite is negligible (or at least its contribution to the bulk susceptibility). This relationship, likely different in other bodies, allows for transforming magnetic susceptibility data into density data, helping to constrain gravity modelling when density data from rock samples are scarce. Given the large amount of AMS studies worldwide, together with the quickness and cost-effectiveness of susceptibility measurements with portable devices, this methodology allows for densifying and homogenizing the petrophysical data when modelling granite rock volumes based on both magnetic and gravimetric signals.This work was financed by the projects GeoPiri3D (CGL2017-84901-C2-2-P), UKRIA4D (PID2019-104693GB-I00/CTA) and IMAGYN (PID2020-114273GB-C22) from the Spanish Ministry of Science (funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”). This work is methodologically related also with the 3DGeoEU project financed by the European Commission under the ERANET Cofound action GeoERA (Grant No.: 731166). The GeoAp Research group from the Aragonian Government is also acknowledged. We are also in debt to the staff of the Petrophysical Laboratory (IGME, Tres Cantos) and to the Geophysics technicians (José Mª Llorente and Agustín González). The help of the Rock Magnetism Laboratory of the Centre Européen de Recherche et d’Enseignement de Géosciences de l’Environnement (CEREGE) in Aix en ProvenceMarseille is also acknowledged. P.C. acknowledges funding from PTA2017-14779-I and FJC2019- 041058-I (AEI-Spain) contracts. E.B. thanks the Geomodels Research Institute of the University of Barcelona and GGAC-2017SGR596 (Generalitat de Catalunya).Peer reviewe

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Le quartz et la cinématique des zones ductiles

Ce travail est voué à l'étude de comportement plastique du quartz dans les tectonites, par l'examen au microscope optique des microstructures des sous-structures et des orientations préférentielles de forme et de réseau. en vue d'une analyse cinématique de ces tectonites. Trois zones de grande déformation appelées zones ductiles apportant chacune des contributions spécifiques. sont choisies comme support de l'étude : l'axe Angers- Lanvaux étudié dans la région d'Angers (Massif Armoricain), le Grand Chevauchement Central himalayen au Népal Central et la zone ductile de Maydan (Afghanistan). Le caractère cinématique le plus constant dans ces zones est un écoulement plastique subparallèle à une linéation majeure d'allongement. horizontale ou faiblement pentée ; l'échauffement plastique développé par cet écoulement peut rendre compte, au moins partiellement, du métamorphisme de position lié à ces zones, ainsi que le montre un modèle thermique schématique. Le problème de l'initiation et de la croissance d'une zone ductile est abordé à l'aide d'un modèle basé sur l'existence d'une hétérogénéité locale de la loi de déformation d'une plaque soumise à un couple de cisaillement constant. Un modèle général de zone ductile à plan d'écoulement subverti cal (par opposition aux grands chevauchements) tente d'intégrer les caractéristiques communes à ces zones.pas de résum

Structure des massifs granitiques de la Méséta marocaine, marqueurs géodynamiques : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) et Sebt de Brikiine (Rehamna)

Structure of the Moroccan Meseta granitic intrusions, geodynami-cal markers : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) and Sebt de Brikiine (Rehamna). The Moroccan Meseta is in continuity in Africa with the European Hercynian belt. We think the structural study of granitoids constitues one way to reconstruct the geodynamic evolution of this Hercynian domain. This is because, the structures of partially melted and solid rocks, concerning the granites and the country-rocks, behave as markers of the emplacement of granite bodies in the crust. The magmatic structures in the granitoids have been studied using the anisotropy of magnetic susceptibility (AMS) technique. With respect to the classical structural analysis, the main advantages are a great reliability in the orientation measurement of foliation, and especially of lineation, and the easy quantification of total, planar and linear anisotropics using the magnitudes of the AMS ellipsoid. Three granite massifs are presented in detail. The composite Aouli-Bou-Mia massif in the Eastern Meseta is considered as the earliest of the Mesetian orogen. Structural analysis of the country rocks, along with the concordant regulary oriented magmatic structures, allow to propose a syn-to late-tectonic emplacement of the granite during a low-angle shearing of the country-rocks. However, the com-pressional or extensional context of this event cannot be specified. The granodioritic massif of Zaër (Central Massif), like the Oulmès body studied elsewhere, seems to be associated with the NNE-SSW sinistral transcurrent faults that transect the Western Meseta. In agreement with the radiochronological data, a detailed analysis shows that the monzogranitic body that occupies the south-center of the Zaër massif was emplaced during a late, brittle event, into the already cooled granodiorite. At the western Mesetian boundary, emplacement of the alkaline granitic massif of Sebt has been accomplished along the Western Meseta Shear Zone, during its very last dextral transcurent movements. Compatibility of the extensive Devono-Dinantian events, typical of the Western Meseta, with the low-angle shearing tectonics of the eastern domain at the same period favors the hypothesis of a generalized extensive event during the onset of the Mesetian orogen. Later, during Westphalian times, the account of the large transcurrent faults in the same regional stress system leads us to consider that the Sehoul Block is responsible for the north-south punching of the Meseta previously softened by the extensional event. This tectonic event prevailing in North-West Meseta possibly took place during, and lasted after, the E-W compression event typical of the post-Visean phase, and which was responsible for the NE-SW regional structures of the whole Meseta.La Meseta marocaine constitue sur le continent africain la continuité de la chaine hercynienne d'Europe moyenne. On pense que l'étude des structures internes de granitoïdes constitue l'une des façons de retracer l'évolution géodynamique de ce segment hercynien. En effet, les structures de déformation à l'état partiellement fondu dans les plutons, et à l'état solide, dans les plutons et leur encaissant, sont l'empreinte de la mise en place dans la croûte de ces plutons. Les structures dans les granites sont étudiées par la technique de l'anisotropie de la susceptibilité magnétique. Par rapport à l'analyse structurale classique les avantages essentiels sont : - une grande fiabilité des mesures d'orientation des foliations et surtout des linéations ; - la quantification des anisotropics totale, planaire et linéaire. Trois massifs granitiques sont présentés en détail. Le massif composite d'Aouli-Bou-Mia, en Meseta orientale, est considéré comme le plus précoce de l'orogène mésétien. L'analyse de la déformation de son encaissant, ainsi que ses structures magmatiques orientées de façon très régulière conduisent à proposer une mise en place syn-à tardi-tectonique dans un encaissant soumis à un cisaillement d'angle faible, mais le contexte compressif ou distensif ne peut être précisé. Le massif granodioritique de Zaër (Massif Central) semble, comme celui d'Oulmès étudié par ailleurs, associé aux décrochements sénes-tres NNE-SSW qui parcourent la Meseta occidentale. L'analyse structurale détaillée montre, en accord avec les données radiochronologiques, que le corps monzogranitique occupant le centre-sud du massif du Zaër s'est mis en place tardivement au cours d'un épisode fragile au sein de la granodiorite préalablement refroidie. En bordure occidentale de la Meseta, la mise en place du massif granitique à affinité alcaline de Sebt de Brikiine s'est effectuée le long de la zone de cisaillement de la Meseta Occidentale, lors de ses ultimes jeux décrochant dextres. La compatibilité des phénomènes distensifs dévono-dinantiens de la Meseta Occidentale avec le cisaillement d'angle faible reconnu dans le domaine oriental serait en faveur de l'hypothèse d'une extension généralisée en début d 'orogène (~ 330 MA). Par la suite, au West-phalien, si l'on veut rendre compte des grands décrochements crus-taux nord-mésétiens dans un même système de contrainte, on est conduit à envisager un poinçonnement nord-sud de la Meseta par le Bloc des Sehoul. Ce domaine exotique, à structures clairement sécantes sur celles de la Meseta, joue le rôle de coin de socle entre le Bloc Côtier et la partie est de la Meseta occidentale. Cet événement tectonique dominant dans la partie Nord-Ouest de la Meseta est probablement intervenu pendant et après la phase de serrage E-W post viséenne qui confère à toute la Meseta ses structures régionales NE-SW.Diot Hervé, Bouchez Jean-Luc. Structure des massifs granitiques de la Méséta marocaine, marqueurs géodynamiques : Aouli-Bou-Mia (Haute Moulouya), Zaër (Massif Central) et Sebt de Brikiine (Rehamna). In: Géologie Méditerranéenne. Tome 18, numéro 1-2, 1991. Le paleozoïque du Maroc. II – Carbonifère – Permien (Paléontologie – Biostratigraphie – Aspects structuraux) pp. 81-97