Roles of the Drosophila SK Channel (dSK) in Courtship Memory

A role for SK channels in synaptic plasticity has been very well-characterized. However, in the absence of simple genetic animal models, their role in behavioral memory remains elusive. Here, we take advantage of Drosophila melanogaster with its single SK gene (dSK) and well-established courtship memory assay to investigate the contribution of this channel to memory. Using two independent dSK alleles, a null mutation and a dominant negative subunit, we show that while dSK negatively regulates the acquisition of short-term memory 30 min after a short training session, it is required for normal long-term memory 24 h after extended training. These findings highlight important functions for dSK in courtship memory and suggest that SK channels can mediate multiple forms of behavioral plasticity

Intérêt de la dimension émotionnelle d’une information à destination des patients atteints d’un syndrome d’apnées obstructives du sommeil

International audienc

A phenomenological model for high temperature oxidation of Si3N4-TiN composites

5th International Symposium on High Temperature Corrosion and Protection of Materials, LES EMBIEZ, FRANCE, MAY 22-26, 2000International audienceBased on microstructural and chemical analyses, a phenomenological model is proposed in order to describe the high temperature oxidation of Si3N4-TiN ceramics. The model consists of three steps in the 1000-1200 degreesC temperature range. In a first step, the oxidation of the TiN phase is controlled by the diffusion of Ti through TiO2 formed at the outer surface, leading to the formation of a porous sub-layer. Simultaneously, the Si3N4 phase oxidation is controlled by oxygen diffusion through SiO2. In a second step, the oxidation of inner TiN phase is controlled by the diffusion of oxygen through TiO2. The Si3N4 transformation into SiO2 leads to a high molar volume increase, SiO2, which is vitreous in the considered temperature range, creeps in the sub-layer porosity. In a third step, SiO2 forms a continuous sub-layer, and oxidation is controlled by the diffusion of O through this layer. The kinetic laws proposed from this phenomenological model are in good agreement with thermogravimetric analyses between 1000 degreesC and 1100 degreesC. For higher temperatures, fluctuations in the experimental curves seem to indicate a succession of fracture and crack healing in the oxide layer

Hot-crack test for aluminium alloys welds using TIG process

Hot cracking is a critical defect frequently observed during welding of aluminium alloys. In order to better understand the interaction between cracking phenomenon, process parameters, mechanical factors and microstructures resulting from solidification after welding, an original hot-cracking test during welding is developed. According to in-situ observations and post mortem analyses, hot cracking mechanisms are investigated, taking into account the interaction between microstructural parameters, depending on the thermal cycles, and mechanical parameters, depending on geometry and clamping conditions of the samples and on the thermal field on the sample. Finally, a process map indicating the limit between cracking and non-cracking zones according to welding parameters is presented

SRAL, A RADAR ALTIMETER DESIGNED TO MEASURE A WIDE RANGE OF SURFACE TYPES

SCOPE In the context of Global Monitoring for Environment and Security (GMES), the objectives of the Sentinel-3 mission driven by ESA encompass the commitment to consistent, long-term collection of remotely sensed data of uniform quality in the areas of sea/land topography and ocean colour. The Sentinel-3 satellite indeed carries a topography mission including mainly RF instruments and an ocean and land colour mission composed of optical instruments. The aim of this paper is to describe the core instrument of the topography mission [1], the SRAL radar altimeter [2], and its latest development steps. OVERVIEW OF SRAL MISSION REQUIREMENTS The SRAL (Sar Radar ALtimeter) instrument is not only specified to retrieve the classical parameters used in the oceanography field such as the Sea Surface Height (SSH), the Significant Wave Height (SWH) and the sea wind speed but it also makes it possible to perform range measurements over the following surfaces: Sea ice Ice sheet interiors (e.g. Antartic plateau) Ice margins In-land waters To achieve these objectives, SRAL will be supported by the other elements of the topography payload : A microwave radiometer which corrects for the tropospheric delay; A real-time navigation system implemented by a GPS equipment; A Laser Retro-Reflector Assembly to provide calibration of range measurements. The SRAL mission requirements and the topography payload will be reminded in the first section of this paper. SRAL MAIN FUNCTIONS SRAL is a nadir-looking radar operating in dual frequency (Ku-band used as main frequency and Cband used for ionospheric corrections over ocean). The nadir swath allows using the simple deramp technique to perform radar pulse compression

Numerical Prediction of Microstructures by a Coupled Model (CA-FE) for Laser Beam Melting of Single-Track 316L Stainless Steel

International audienc

Habenula lesions alter synaptic plasticity within the fimbria-accumbens pathway in the rat.

Both the habenula and the nucleus accumbens, and especially the glutamatergic innervation of the latter from the hippocampus, have been hypothesized to be involved, in different ways, in the pathophysiology of cognitive disturbances in schizophrenia. Lesions of the habenula produce disturbances of memory and attention in experimental animals. As the habenular nuclei have been shown to influence the release of many neurotransmitters, both in the hippocampus and the nucleus accumbens, we examined in this study the effects of bilateral habenula lesions on the plasticity of the fimbria-nucleus accumbens pathway, by means of the long-term depression phenomenon in freely moving rats. Long-term depression, induced within the shell region of the nucleus accumbens by low-frequency stimulation of the fimbria, was exaggerated and showed greater persistence in habenula-lesioned rats compared with sham-operated animals. These results indicate that plasticity in the fimbria-nucleus accumbens pathway is altered by habenula lesions in a way similar to previously-reported effects of stress and the psychosis-provoking agent ketamine. Moreover, they strengthen the views that the habenula belongs to systems, mediating higher cognitive functions, which involve the hippocampus and the nucleus accumbens. Finally, this study suggests that dysfunction of the habenula could contribute to cognitive alterations in diseases such as schizophrenia, where the habenula is reported to exhibit exaggerated calcification

Failure prediction for ceramic dies in the hot-forging process using FEM simulation

International audienceA fracture prediction criterion for brittle materials has been introduced in the POLLUX finite-element code, in order to predict the risk of rupture of ceramic tools during a forging operation. The POLLUX code, developed by INSA (Lyon) especially to simulate forging operations, is presented. The fracture model is based on the weakest link theory and Weibull analysis. Two different criteria were chosen in order to characterise the stress state, considering the tensile normal stresses. Comparison between the simulation results and the analytical calculations, in a simple compression case, enables the validation of the numerical model. Applications are presented, in which the design of ceramic forging tools is realized using the failure prediction software. A run-strategy of the program is proposed in order to improve the design of the forging tool