Re-Evaluation of Sinocastor (Rodentia: Castoridae) with Implications on the Origin of Modern Beavers

The extant beaver, Castor, has played an important role shaping landscapes and ecosystems in Eurasia and North America, yet the origins and early evolution of this lineage remain poorly understood. Here we use a geometric morphometric approach to help re-evaluate the phylogenetic affinities of a fossil skull from the Late Miocene of China. This specimen was originally considered Sinocastor, and later transferred to Castor. The aim of this study was to determine whether this form is an early member of Castor, or if it represents a lineage outside of Castor. The specimen was compared to 38 specimens of modern Castor (both C. canadensis and C. fiber) as well as fossil specimens of C. fiber (Pleistocene), C. californicus (Pliocene) and the early castorids Steneofiber eseri (early Miocene). The results show that the specimen falls outside the Castor morphospace and that compared to Castor, Sinocastor possesses a: 1) narrower post-orbital constriction, 2) anteroposteriorly shortened basioccipital depression, 3) shortened incisive foramen, 4) more posteriorly located palatine foramen, 5) longer rostrum, and 6) longer braincase. Also the specimen shows a much shallower basiocciptal depression than what is seen in living Castor, as well as prominently rooted molars. We conclude that Sinocastor is a valid genus. Given the prevalence of apparently primitive traits, Sinocastor might be a near relative of the lineage that gave rise to Castor, implying a possible Asiatic origin for Castor

Modélisation et incertitude : comparison de deux méthodes pour l'estimation de la confiance des résultats des modèles numériques

The problem developed and analyzed in this paper is that of the estimation of the uncertainty associated with the results obtained by numerical simulation codes of physical systems induced from input data. In the first section, a general problem is developed and the authors describe briefly the methods used to calculate the uncertainty domain. They present two classic methods, one is a probability method, the Monte-Carlo method; the other, a determinist method, a differential analysis with finite differences. In the second section, two examples of models of thermal behaviour of building are used to underline the advantages and the drawbacks of both methods. These models are extracted fractions of larger models allowing a simplified presentation of the methods proposed. The authors determine the uncertainty domains on outputs simultaneously with the two methods. They show that the obtained domain by differential analysis is lightly pessimistic, but very near to those of the Monte-Carlo method, in the case of first model, linear, like in the case of second, highly nonlinear. The differential analysis is clearly more economical in calculation time and makes it possible to identify sensitive data with significant bearing on output uncertainty. Nevertheless, it is emphasized that for this method it is essential to enter into the calculation code formalism. globally, the authors conclude that a relative superiority of the differential analysis exists, particularly in the case of large codes where Monte-Carlo use would be prohibitive in calculation time.Le problème développé dans ce texte est celui de l'estimation de l'incertitude associée aux résultats produits par les codes de simulation numérique des systèmes physiques, induite par les incertitudes des données d'entrée. Dans la première partie, les auteurs posent le problème général et décrivent brièvement les méthodes utilisées pour calculer l'amplitude du domaine d'incertitude. Ils présentent deux méthodes types, l'une probabiliste, la méthode de Monte-Carlo, l'autre déterministe, l'analyse différentielle aux différences finies. Dans la deuxième partie, deux exemples de modèles de comportement thermique de locaux de bâtiments sont utilisés pour mettre en évidence les avantages et les inconvévients des deux méthodes. Ces modèles sont des fractions extraites de grands modèles, permettant de simplifier la présentation des méthodes proposées. Pour le premier, les échanges thermiques sont découplés et on ne traite pas la covection, ce qui conduit à la résolution d'un système linéaire des radiosités de dimension 10. Les auteurs montrent ainsi que l'incertitude relative de la norme du vecteur des radiosités est de l'ordre de 19 %, pour des incertitudes de données expérimentales usuelles. Pour le second, les échanges sont couplés et le modèle est fortement non linéaire. Les incertitudes obtenues pour les températures de surface des parois du local étudié sont de l'ordre de 3 %. Les auteurs concluent en faveur de l'analyse différentielle, nettement plus économe en temps de calcul et permettant d'identifier les entrées sensibles agissant de manière prépondérante sur l'incertitude des sorties. Néanmoins, on souligne, pour cette méthode, la nécessité d'entrer dans le formalisme du code de calcul. Globalement, les auteurs concluent à une relative supériorité de l'analyse différentielle, en particulier dans le cas des grands codes dont l'exploitation en Monte-Carlo serait prohibitive en temps de calcul

A novel minimal invasive closed chest myocardial ischaemia reperfusion model in rhesus monkeys ( Macaca mulatta ): improved stability of cardiorespiratory parameters

International audienc

Cyclic PNA-based compound directed against HIV-1 TAR RNA: modelling, liquid-phase synthesis and TAR binding

International audiencexx

Cyclic PNA hexamer-based compound: modelling, synthesis and inhibition of the HIV-1 RNA dimerization process

International audiencexx

Amorphous silicate nanoparticles with controlled Fe-Mg pyroxene compositions

The production of amorphous pyroxene nanoparticles (~ 20 nm) with controlled Fe-Mg content is described. Homogenous particle compositions closely matching required target stoichiometries are obtained by drying a precursor gel under high vacuum conditions. The silicate nature of the particles is characterised using TEM, synchrotron radiation and FTIR. No oxide phase separation occurs, even at high Fe concentration. Structural domains exist within the nanoparticles that are typically ten times smaller than the physical particle size consistent with either a core-shell, or, random network with multiple embedded domains, particle structure. Thermal annealing below the crystallisation temperature allows the ordered domain size to be further reduced by a factor of ~ 2