Échanges et colonisations fauniques (Ammonitina) entre Téthys et Atlantique sud au Crétacé supérieur : voies atlantiques ou sahariennes ?

International audienceGénéralement considéré comme une période chaude, le Crétacé supérieur témoigne d'une extension maximale des domaines marins. Les optima transgressifs du Cénomanien et du Turonien inférieur induisent la création de nouveaux domaines de mer épicontinentale sur les régions sahariennes (mer Transsaharienne). Pendant cette période, les faunes d'ammonites sont remarquablement homogènes entre 60° N et 60° S. À partir de ces stocks d'ammonites cosmopolites, mais très largement inféodés aux environnements ouverts de plates-formes distales, s'individualisent à plusieurs reprises des groupes capables de coloniser les régions sahariennes. Ces groupes généralement endémiques, ont des morphologies très convergentes; des voies de migration nord (à partir des marges sud de la Téthys) ou sud (à partir des marges de l'Atlantique sud, via le Fossé de la Bénoué) peuvent avoir canalisé simultanément la colonisation de la mer transsaharienne

The ammonite fauna of the 'marls with ferruginous fossils' from the Niort region, France (Lower Oxfordian, Cordatum Zone, Cordatum Subzone)

A new collection of ammonites from the 'marls with ferruginous ammonites' in the Niort region (France), previously studied by GROSSOUVRE (1922), provides a large amount of biostratigraphic, paleoenvironmental and paleogeographic information. The fauna is dated Early Oxfordian: Cordatum Zone, Cordatum Subzone, probably the lower part of it. In addition, it is unique in western Europe owing to: 1) the species found of which some appear to be known only in this deposit 2) by the extremely atypical domination of the couple Taramelliceras - Creniceras which represent 2/3 of the specimens. Furthermore, the aspect of the fauna strongly suggests that the habitat was a distal platform unknown in other European strata of the same age. A detailed description of the several species is given, sometimes accompanied by a new taxonomic interpretation.Une nouvelle récolte d'ammonites dans les marnes à ammonites ferrugineuses de la région de Niort (France), autrefois étudiées par de GROSSOUVRE (1922), apporte de très nombreuses informations biostratigraphiques, paléoenvironnementales et paléobiogéographiques. La faune est datée de l'Oxfordien inférieur : Zone à Cordatum, Sous-Zone à Cordatum, partie inférieure probable. De plus, elle est unique en Europe occidentale 1) par les espèces trouvées -dont certaines ne semblent connues que dans ce gisement- 2) par la domination très atypique du binôme Taramelliceras - Creniceras qui représente les 2/3 des individus. Enfin, le spectre faunique plaide en faveur d'un milieu de plate-forme distale inconnu dans les autres gisements européens de même âge. Une figuration détaillée des différentes espèces est donnée, parfois accompagnée d'une nouvelle interprétation taxonomique

Polarity Control in Group-III Nitrides beyond Pragmatism

Controlling the polarity of polar semiconductors on nonpolar substrates offers a wealth of device concepts in the form of heteropolar junctions. A key to realize such structures is an appropriate buffer-layer design that, in the past, has been developed by empiricism. GaN or ZnO on sapphire are prominent examples for that. Understanding the basic processes that mediate polarity, however, is still an unsolved problem. In this work, we study the structure of buffer layers for group-III nitrides on sapphire by transmission electron microscopy as an example. We show that it is the conversion of the sapphire surface into a rhombohedral aluminum-oxynitride layer that converts the initial N-polar surface to Al polarity. With the various AlxOyNz phases of the pseudobinary Al2O3-AlN system and their tolerance against intrinsic defects, typical for oxides, a smooth transition between the octahedrally coordinated Al in the sapphire and the tetrahedrally coordinated Al in AlN becomes feasible. Based on these results, we discuss the consequences for achieving either polarity and shed light on widely applied concepts in the field of group-III nitrides like nitridation and low-temperature buffer layers

Mucous Membrane Pemphigoid in a Nonagenarian: A Case Report

Mucous membrane pemphigoid is a rare autoimmune blistering disease characterized by post-bullous erosion of mucous membranes. Herein, we present a case of a nonagenarian man who was referred to our department of dermatology presenting with painful erosion of the buccal mucosa. Physical examination revealed palate erosion associated with erosion of the buccal mucosa. A diagnosis of mucous membrane pemphigoid was confirmed, and the patient was successfully treated with topical corticosteroids

Visual Reasoning with Multi-hop Feature Modulation

International audienceRecent breakthroughs in computer vision and natural language processing have spurred interest in challenging multi-modal tasks such as visual question-answering and visual dialogue. For such tasks, one successful approach is to condition image-based convolutional network computation on language via Feature-wise Linear Modulation (FiLM) layers, i.e., per-channel scaling and shifting. We propose to generate the parameters of FiLM layers going up the hierarchy of a convolutional network in a multi-hop fashion rather than all at once, as in prior work. By alternating between attending to the language input and generating FiLM layer parameters, this approach is better able to scale to settings with longer input sequences such as dialogue. We demonstrate that multi-hop FiLM generation achieves state-of-the-art for the short input sequence task ReferIt-on-par with single-hop FiLM generation-while also significantly outperforming prior state-of-the-art and single-hop FiLM generation on the GuessWhat?! visual dialogue task

Chronic Eczematous Eruptions of the Elderly Are Associated with Chronic Exposure to Calcium Channel Blockers: Results from a Case–Control Study

It has been suggested that chronic eczematous eruptions of the elderly could be associated with chronic drug exposure. To determine the drugs associated with these eruptions, we conducted a case–control study on 102 cases and 204 controls. Cases were consecutive patients older than 60 years presenting with an eczematous eruption that had evolved continuously or recurrently for more than 3 months without a reliable cause. Two controls were matched to each case on age, sex, in/outpatient origin, and center. Information about drug exposure was obtained from patients and their pharmacists. Drug use for more than 3 months within the year preceding the eruption was compared between cases and controls. An association was found between calcium channel blockers (CCB) and eczema, with a matched OR (odds ratio) of 2.5 (95% CI (confidence interval): 1.3–4.6). To ascertain the course of patients after CCB withdrawal, two ancillary studies were performed on 74 patients with eczematous eruptions from our department before the case–control study period, and on 101 patients registered in the French “Pharmacovigilance” database. Healing of these eruptions after CCB withdrawal occurred in 83 and 68% of these cases, respectively. The long-term use of CCB is a risk factor for chronic eczematous eruptions of the elderly

Quelques échinides calloviens

National audienc

Associations de trilobites sud- et centre-armoricaines : succession stratigraphique

National audienceLes ex-"Schistes a Calymenes" Auct. livrent plusieurs assemblages typiques a trilobites (ayant eux-memes, au mains pour partie, unevafeur biochronologique). Dans les grandes lignes, deux domaines faunes relativement differentes coexistent, localises respectivementau sud (region la plus connue) et au nord de Rennes. Globalement, au sud (Synclinorium de Martigne-Ferchaud), c'est la Formation deTraveusot qui livre les assemblages les plus habituels ; au nord, dans le Synclinorium median, son equivalent lithologique principal correspond ala Formation d'Andouille et, vers l'ouest, a la Formation de Postolonnec (cette derniere incluant de tres nombreux membres). Ces ensembleslithologiques, surtout silto-argileux (mais incluant parfois des corps greseux bien developpes, surtout au nord de Rennes), couvrent unintervalle encadrant la limite Darriwilien-Sandbien (series LlanvirnCaradoc) : pour ce qui est pour !'instant prouve (c'est-a-dire date parles seuls marqueurs standards reconnus), les parties les plus anciennes des formations a trilobites sont d'age Darriwilien moyen basal (biozonea calix) ; les plus recentes d'age Sandbien "moyen" (biozone a deunff1). On notera qu'il existe au mains un "episode" a trilobites plus recent(ou plusieurs ?), "synchrone(s)", souvent difficilement reperable(s) en raison des conditions mediocres ou nu lies d'affleurement :remarquablement homogene par son (leur) contenu a l'echelle de tout le Massif armoricain, il(s) caracterise(nt) les biozones a tanvillensislrobustaZones de chitlnozoalres brevis bacula to symmetrica brevicolfis de la base du Katien (fin de la serie Caradoc)