57 research outputs found
Tectonic evolution of the Eastern Moroccan Meseta: from Late Devonian foreâarc sedimentation to Early Carboniferous collision of an Avalonian promontory
This study was founded by the Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR (CGL2015-71692-P) and the Doctoral scholarship BES-2016-078168. GeoHistory Facility instruments were funded via an Australian Geophysical Observing System grant provided to AuScope Pty Ltd. by the AQ44 Australian Education Investment Fund program. The NPII multicollector was obtained via funding from the Australian Research Council LIEF program (LE150100013). The authors want to express their gratitude to Dr. Manuel Francisco Pereira (University of Evora, Portugal) and Dr. Michel Villeneuve (Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, France) for their constructive reviews that helped to improve the quality of the original manuscript. Special thanks to Brad McDonald (Curtin University, Australia) for technical assistance regarding LA-ICPMS and Hf analyses, Profs. Abdelfatah Tahiri (University Mohammed V of Rabat, Morocco) and Hassan El Hadi (University Hassan II of Casablanca, Morocco) for their support during field work, Prof. Yvette Kuiper (Colorado School of Mines, USA) for her precious hints about the interpretation of Hf data, and Dr. Lorenzo Valetti for proofreading the manuscript. Supporting information can be obtained in Mendeley Data: https://doi.org/10.17632/b8fdbykmbx.1 (https://data.mendeley.com/datasets/b8fdbykmbx/draft?a=eaae2da0-8e224056-861b-4824984f1c10).The deformed Paleozoic succession of the Eastern Moroccan Meseta crops out in relativelysmall and isolated inliers surrounded by Mesozoic and Cenozoic rocks. Two of the largest inliers(Mekkam and Debdou) are characterized by a monotonous succession of slates and greywackes affected bypolyphasic folding that occurred at lowâto very low grade metamorphic conditions. New UâPb ages ondetrital zircon grains from the DebdouâMekkam metasediments constrain the maximal depositional age asLate Devonian, interpreted to be close to the true sedimentation age. Furthermore, theΔHfvalues of theDevonian detrital zircons, together with the presence of a series of scattered zircon grains with ages betweenc. 0.9 and c. 1.9 Ga, suggest provenance from a subductionârelated magmatic arc located on the Avalonianmargin. The DebdouâMekkam massif is characterized by an Early Carboniferousfirst deformationalevent (D1), which gave way to a pervasive cleavage (S1) associated with plurikilometricâscale, tight toisoclinal, overturned to recumbent folds. Later events (Dc) occurred at Late Carboniferous time andgenerated variably developed crenulation cleavages (Sc) associated with variously oriented metricâtokilometricâscale folds, which complicate the pattern of both D1 intersection lineations (L1) and axial traces.The restoration of this pronounced curved pattern yields originally SWâNEâoriented D1 fold axes withregional SEâvergence. This important Early Carboniferous shortening and SEâdirected tectonic transport canbe explained by closure of the Rheic Ocean and thefirst phases of the collision between the northern passivemargin of Gondwana and an Avalonian promontory.Ministerio de Economia y Competitividad (MINECO) of Spain
CGL2015-71692-P
BES-2016-078168Australian Geophysical Observing SystemAustralian Education Investment Fund program
AQ44Australian Research Council
LE15010001
Mesures de spectrométrie et de dosimétrie neutron aux postes de travail pour l'étalonnage de dosimÚtres individuels PGP-DIN
International audience(ManuAcrit r e p le 3 juillet 2002, accepté le 29 septembre 2002) Dans le cadre de la mise en application des recommandations décrites dans la publication 60 de la CIPR, des mesures de spectrométrie neutron ont été réalisées à plusieurs postes de travail au CEA de Valduc. Le but de ces mesures était la détermination de nouveaux coefficients d'étalonnage h affecter aux dosimÚtres individuels neutron PGP-DIN afin de restituer correctement les doses reçues par les opérateurs séjournant h ces postes. Ces mesures ont été effectuées au cours de deux campagnes successives. La tluence neutronique et le débit d'équivalent de dose amhiantH*(IO) ont été mesurés en fonction de l'énergie avec le spectromÚtre ROSPEC et un systÚme de sphÚres de BONNER. Les champs de radiations étant toutefois mixtes, c'est-à -dire présentant une composante neutronique et photonique, des mesures de débits d'équivalent de dose ambiant photon aux postes de travail considérés ont également été réalisées à l'aide de débitmÚtres d'ambiance. Les dosimÚtres individuels PGP-DIN ont été positionnés sur un fantÎme (ISO) d'eau. Des calculs effectués h l'aide du code MCNP ont été comparés aux résultats expérimentaux. Neutron spectrometry and dosimetry measurement at workplaces for calibration of individual PGP-DIN dosimeters. Measurements to determine new coefficients for individual neutron dosimeters PGP-DIN complying with the ICRP 60 recommendations were performed at two workplaces at the CEA of Valduc: a storage r w m and a plutonium reprocessing plant. Two spectrometry campaigns were performed allowing a better assessment of doses received by operators worki.ng at these workplaces. Neutron energy fluence and ambient dose equivalent rate H*(10) distributions were measured as function of neutron energy by using the ROSPEC device and BONNER spheres spectrometer. The radiation field being mixed neutron and gamma, the gamma component was also evaluated: neutron and photon dose-rate meters were nsed to evaluate the ambient dose rate equivalent. Individual dosemeters were positioned on an ISO water slab phantom. In addition, calculations were performed using the MCNP simulation code for different configurations. ' Insiitui de radioprotection ct de sûre16 nucléaire, DPHD, B.P. 17. 92262 Fontcnay-aux-Roses Cedcx, France
Mesures de spectrométrie et de dosimétrie neutron aux postes de travail pour l'étalonnage de dosimÚtres individuels PGP-DIN
Vinflunine in routine clinical practice for the treatment of advanced or metastatic urothelial cell carcinoma - data from a prospective, multicenter experience
Phylogeny and Diversification Patterns among Vesicomyid Bivalves
Vesicomyid bivalves are among the most abundant and diverse symbiotic taxa in chemosynthetic-based ecosystems: more than 100 different vesicomyid species have been described so far. In the present study, we investigated the phylogenetic positioning of recently described vesicomyid species from the Gulf of Guinea and their western Atlantic and Pacific counterparts using mitochondrial DNA sequence data. The maximum-likelihood (ML) tree provided limited support for the recent taxonomic revision of vesicomyids based on morphological criteria; nevertheless, most of the newly sequenced specimens did not cluster with their morphological conspecifics. Moreover, the observed lack of geographic clustering suggests the occurrence of independent radiations followed by worldwide dispersal. Ancestral character state reconstruction showed a significant correlation between the characters âdepthâ and âhabitatâ and the reconstructed ML phylogeny suggesting possible recurrent events of âstepwise speciationâ from shallow to deep waters in different ocean basins. This is consistent with genus or species bathymetric segregation observed from recent taxonomic studies. Altogether, our results highlight the need for ongoing re-evaluation of the morphological characters used to identify vesicomyid bivalves
On the evolutionary ecology of symbioses between chemosynthetic bacteria and bivalves
Mutualistic associations between bacteria and eukaryotes occur ubiquitously in nature, forming the basis for key ecological and evolutionary innovations. Some of the most prominent examples of these symbioses are chemosynthetic bacteria and marine invertebrates living in the absence of sunlight at deep-sea hydrothermal vents and in sediments rich in reduced sulfur compounds. Here, chemosynthetic bacteria living in close association with their hosts convert CO2 or CH4 into organic compounds and provide the host with necessary nutrients. The dominant macrofauna of hydrothermal vent and cold seep ecosystems all depend on the metabolic activity of chemosynthetic bacteria, which accounts for almost all primary production in these complex ecosystems. Many of these enigmatic mutualistic associations are found within the molluscan class Bivalvia. Currently, chemosynthetic symbioses have been reported from five distinct bivalve families (Lucinidae, Mytilidae, Solemyidae, Thyasiridae, and Vesicomyidae). This brief review aims to provide an overview of the diverse physiological and genetic adaptations of symbiotic chemosynthetic bacteria and their bivalve hosts
Techniques de dosimétrie physique pour la reconstitution d'accident radiologique
Suite à un accident radiologique, il est important d'estimer rapidement la distribution de la dose reçue par l'organisme. Cette information, qui vient en complément des investigations cliniques et
biologiques, s'avÚre d'une grande utilité pour les médecins. à cette fin, la dosimétrie physique utilise des moyens de reconstitution numériques et expérimentaux, généralement complémentaires.
La reconstitution numérique consiste, à l'aide d'un code de calcul basé sur une méthode probabiliste de Monte-Carlo, à simuler le transport des particules dans une géométrie représentant
l'accidenté et son evironnement. La reconstitution expérimentale est réalisée à l'aide de fantÎmes équivalents tissu et de dosimÚtres adaptés
Mesures de spectrométrie et de dosimétrie neutron aux postes de travail pour l'étalonnage de dosimÚtres individuels PGP-DIN
Dans le cadre de la mise en application des recommandations décrites
dans la publication 60 de la CIPR, des mesures de spectrométrie neutron
ont été réalisées à plusieurs postes de travail au CEA de Valduc. Le but
de ces mesures était la détermination de nouveaux coefficients d'étalonnage
Ă affecter aux dosimĂštres individuels neutron PGP-DIN afin de restituer
correctement les doses reçues par les opérateurs séjournant à ces postes.
Ces mesures ont été effectuées au cours de deux campagnes successives. La fluence
neutronique et le débit d'équivalent de dose ambiant (10) ont été mesurés en
fonction de l'Ă©nergie avec le spectromĂštre ROSPEC et un systĂšme de sphĂšres de BONNER.
Les champs de radiations étant toutefois mixtes, c'est-à -dire présentant une
composante neutronique et photonique, des mesures de débits d'équivalent de dose
ambiant photon aux postes de travail considĂ©rĂ©s ont Ă©galement Ă©tĂ© rĂ©alisĂ©es Ă
l'aide de débitmÚtres d'ambiance. Les dosimÚtres individuels PGP-DIN ont été
positionnés sur un fantÎme (ISO) d'eau. Des calculs effectués à l'aide du code
MCNP ont été comparés aux résultats expérimentaux
- âŠ