Enzyme activity below the dynamical transition at 220 K

Enzyme activity requires the activation of anharmonic motions, such as jumps between potential energy wells. However, in general, the forms and time scales of the functionally important anharmonic dynamics coupled to motion along the reaction coordinate remain to be determined. In particular, the question arises whether the temperature-dependent dynamical transition from harmonic to anharmonic motion in proteins, which has been observed experimentally and using molecular dynamics simulation, involves the activation of motions required for enzyme function. Here we present parallel measurements of the activity and dynamics of a cryosolution of glutamate dehydrogenase as a function of temperature. The dynamical atomic fluctuations faster than ~100 ps were determined using neutron scattering. The results show that the enzyme remains active below the dynamical transition observed at ~220 K, i.e., at temperatures where no anharmonic motion is detected. Furthermore, the activity shows no significant deviation from Arrhenius behavior down to 190 K. The results indicate that the observed transition in the enzyme's dynamics is decoupled from the rate-limiting step along the reaction coordinate

Coupling SPH with a 1-D Boussinesq-type wave model

International audienceThe high computational cost of SPH remains problematic in dealing with wave propagation, especially when the domains considered are large. In order to overcome this difficulty, we propose to couple 2-D SPH with a 1-D Finite Difference Boussinesq-type model. The latter deals with wave propagations for most of the spatial domain, whereas SPH computations focus on the shoreline or close to off-shore structures, where a complex description of the free-surface is required. The re-use of existing codes is achieved using a generic implementation based on Component Technology. The communication between software is ensured by the middleware Component Template Library (CTL). In order to deal with open domains, open-boundaries have to be implemented for SPH, with water height and velocity varying in space and time. These velocity and water height values are then driven by the Boussinesq-type model. As an illustration of the one way coupling, we present herein two simple examples of water waves, the first one with a flat bottom, the other one representing a schematic coastal protection

Aeroelastic implications of active winglet concept aimed to improve civil transport aircraft performances

Reduction of aircraft environmental footprint has become over years a key objective for the industry. Particularly, for decades winglets have been proven to eficiently reduce drag and fuel consumption. However, the design of those wingtip extensions mainly relies on an aerodynamic shape optimisation for a given cruise condition resulting in suboptimal behaviour for the rest of the flight. Active winglet concept proposes to optimise the winglet cant angle along the flight to compensate the loss of eficiency inherent to fixed designs. The variation of winglet deflection impacts the lift distribution with repercussion on wing deformation that must be investigated. Besides, the presence of moving masses at the tip of the wing also has influence on dynamic response and particularly on flutter onset. This work proposes to evaluate those impacts through an aeroelastic analysis of both static and dynamic implications of active winglets combined with an aerodynamic performances optimisation. The XRF1, an Airbus provided industrial standard multi- disciplinary research test case representing a typical configuration for wide body long- range aircraft, is used as the baseline aircraft. Coupled CFD/CSM computations are performed to assess the evolution of wing shape with respect to winglets deflections and the consequences on mission performance optimisation. While a parametric flutter analysis is carried-out to highlight the dependence of critical flutter speed on winglet cant angle

Analyse du discours et représentations sociales de l’homosexualité en Côte d’Ivoire : controverses autour d’une orientation sexuelle

Résumé : Le présent article a pour objet d’étude l’homosexualité une orientation sexuelle devenue sujet de controverse. Elle se propose d’analyser les discours et les représentations sociales produit(e)s sur l’homosexualité suite à la publicisation du phénomène dans les médias et l’effervescence des actes anti-LGBTQI en Côte d’Ivoire. Les résultats indiquent l’existence de discours relatifs à l’homosexualité dont leur traitement par la technique d’analyse de contenu thématique a permis de dégager les représentations sociales de cet objet. Les ivoiriens désapprouvent cette orientation sexuelle eu égard aux items relatifs aux opinions, attitudes et stéréotypes sur l’objet en étude. Dans l’ensemble l’homosexualité est une orientation à proscrire contraire aux mœurs et valeurs culturelles africaine. Elle est une dépravation, une déviation sexuelle. Pratiquer l’homosexualité est immorale, une abomination dont celles ou ceux qui l’observent courent à la perdition. Elle est élevée au rang de péché or le salaire du péché est la mort selon les saintes écritures. C’est un acte condamnable, «acte contre nature», une désacralisation de la sexualité

Disseminated and circulating tumor cells in gastrointestinal oncology.

International audienceCirculating (CTCs) and disseminated tumor cells (DTCs) are two different steps in the metastatic process. Several recent techniques have allowed detection of these cells in patients, and have generated many results using different isolation techniques in small cohorts. Herein, we review the detection results and their clinical consequence in esophageal, gastric, pancreatic, colorectal, and liver carcinomas, and discuss their possible applications as new biomarkers