Transitions to chaos in the wake of an axisymmetric bluff body

This letter aims at understanding the dynamical process that leads to the onset of chaos in the flow past a blunt-based axisymmetric bluff body. On the basis of direct numerical simulations, conducted for Reynolds numbers ranging from 100 to 900, we show that the flow undergoes multiple transitions, successively giving rise to the SS, RSPa, RSPb, RSPc and RSB wake states. In particular, the RSPc state, revealed in this work via long-term computations, is characterized by intermittent vortex stretching denoting the onset of chaos before the symmetry breaking and the occurence of the RSB state

Vers une réutilisabilité totale des algorithmes de traitement d'images

Cet article présente l'évolution des techniques de programmation d'algorithmes de traitement d'images et discute des limites de la réutilisabilité de ces algorithmes. En particulier, nous montrons qu'en C++ un algorithme peut s'écrire sous une forme générale, indépendante aussi bien du type des données que du type des structures de données sur lesquelles il peut s'appliquer. Une réutilisabilité totale des algorithmes peut donc être obtenue ; mieux, leur écriture est plus naturelle et elle n'introduit pas de surcoût significatif en temps d'exécution

Hoatzin nestling locomotion : acquisition of quadrupedal limb coordination in birds

The evolution of flight in birds involves (i) decoupling of the primitive mode of quadrupedal locomotor coordination, with a new synchronized flapping motion of the wings while conserving alternating leg movements, and (ii) reduction of wing digits and loss of functional claws. Our observations show that hoatzin nestlings move with alternated walking coordination of the four limbs using the mobile claws on their wings to anchor themselves to the substrate. When swimming, hoatzin nestlings use a coordinated motion of the four limbs involving synchronous or alternated movements of the wings, indicating a versatile motor pattern. Last, the proportions of claws and phalanges in juvenile hoatzin are radically divergent from those in adults, yet strikingly similar to those of Archaeopteryx. The locomotor plasticity observed in the hoatzin suggests that transitional forms that retained claws on the wings could have also used them for locomotion

IIAC – Laboratoire d’anthropologie et d’histoire de l’institution de la culture (LAHIC)

Marie Scarpa, professeur à l’Université de Metz/Paul-VerlaineJean-Marie Privat, professeur à l’Université de Metz/Paul-VerlaineThierry Wendling, chargé de recherche au CNRSDaniel Fabre, directeur d’étudesFranck Beuvier, Odile Vincent, ingénieurs d’études Marie Scarpa, professeur à l’Université de Metz/Paul-Verlaine Jean-Marie Privat, professeur à l’Université de Metz/Paul-Verlaine Ethnocritique de la littérature Marie Scarpa a poursuivi son étude de la situation de ces personnages des seuils ..

The SWEET-HOME Project: Audio Technology in Smart Homes to improve Well-being and Reliance

International audienceThe SWEET-HOME project aims at providing audio-based interaction technology that lets the user have full control over their home environment, at detecting distress situations and at easing the social inclusion of the elderly and frail population. This paper presents an overview of the project focusing on the implemented techniques for speech and sound recognition as context-aware decision making with uncertainty. A user experiment in a smart home demonstrates the interest of this audio-based technology

Transition-metal-free a-arylation of enolizable aryl ketones and mechanistic evidence for a radical process

The a-arylation of enolizable aryl ketones can be carried out with aryl halides under transition-metal-free conditions using KOtBu in DMF. The a-aryl ketones thus obtained can be used for step- and cost-economic syntheses of fused heterocycles and Tamoxifen. Mechanistic studies demonstrate the synergetic role of base and solvent for the initiation of the radical process

Concerns about the widespread use of rodent models for human risk assessments of endocrine disruptors.

International audienceFetal testis is a major target of endocrine disruptors (EDs). During the last 20 years, we have developed an organotypic culture system that maintains the function of the different fetal testis cell types and have used this approach as a toxicological test to evaluate the effects of various compounds on gametogenesis and steroidogenesis in rat, mouse and human testes. We named this test rat, mouse and human fetal testis assay. With this approach, we compared the effects of six potential EDs ((mono-(2-ethylhexyl) phthalate (MEHP), cadmium, depleted uranium, diethylstilboestrol (DES), bisphenol A (BPA) and metformin) and one signalling molecule (retinoic acid (RA)) on the function of rat, mouse and human fetal testis at a comparable developmental stage. We found that the response is similar in humans and rodents for only one third of our analyses. For instance, RA and MEHP have similar negative effects on gametogenesis in the three species. For another third of our analyses, the threshold efficient concentrations that disturb gametogenesis and/or steroidogenesis differ as a function of the species. For instance, BPA and metformin have similar negative effects on steroidogenesis in human and rodents, but at different threshold doses. For the last third of our analyses, the qualitative response is species specific. For instance, MEHP and DES affect steroidogenesis in rodents, but not in human fetal testis. These species differences raise concerns about the extrapolation of data obtained in rodents to human health risk assessment and highlight the need of rigorous comparisons of the effects in human and rodent models, when assessing ED risk