Hal-Diderot
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Aging characterization of different nitrile butadiene rubbers for sealing in a pneumatic system: Linking the change of the physicochemical state to the mechanical properties
No full textInternational audienceNitrile butadiene rubbers (NBR) are widely used in sealing applications, such as O-rings inside the pneumatic system of the French high-speed train (TGV). In this application, a strong hardening of the NBRs alters the sealing function. Predicting the evolution of the mechanical properties during service life, especially the material hardening, is therefore a strategic issue to optimize time in maintenance operations of the TGV's pneumatic system. The main goal of this study is to reproduce the aging observed on a train's pneumatic system by performing thermo-oxidative accelerated aging tests with different commercial nitrile rubbers at several temperatures and up to 2016 h. After achieving similar degradation to specimens aged on trains, aging mechanisms and effects have been investigated through different characterization techniques: infrared spectroscopy, swelling tests, X-ray fluorescence spectrometry, differential scanning calorimetry, thermogravimetric analysis, and micro-hardness measurements. The results obtained enabled us to identify and to relate aging mechanisms to aging conditions and to precisely determine and quantify the effects of physicochemical state evolution on the mechanical properties of each NBR considered. Extra crosslinks and oxidative functionalities form in the different elastomers, making them hard and brittle, and thus impacting the sealing function
El eusko en el País Vasco francés: una moneda alternativa al servicio de un proyecto de institucionalización del territorio
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Physical modeling of ribosomes along mRNA : estimating kinetic rates from ribosome profiling experiments
No full textInternational audienceGene expression consists in the synthesis of proteins from the information encoded on DNA. One of the two main steps of gene expression is the translation of messenger RNA into polypeptide sequences of amino acids. Here, by taking into account messenger RNA degradation, we model the motion of ribosomes along messenger RNA with a ballistic model where particles advance along a filament without excluded volume interactions. Unidirectional models of transport have previously been used to fit the average density of ribosomes obtained by the experimental ribo-sequencing (Ribo-seq) technique. In this case an inverse fit gives access to the kinetic rates: the position-dependent speeds and the entry rate of ribosomes onto messenger RNA. The degradation rate is not, however, accounted for and experimental data from different experiments are needed to have enough parameters for the fit. Here, we propose an entirely novel experimental setup and theoretical framework consisting in splitting the messenger RNAs into categories depending on the number of ribosomes from one to four. We solve analytically the ballistic model for a fixed number of ribosomes per messenger RNA, study the different regimes of degradation, and propose a criteria for the quality of the inverse fit. The proposed method provides a high sensitivity to the messenger RNA degradation rate. The additional equations coming from using the monosome (single ribosome) and polysome (arbitrary number) ribo-seq profiles enable us to determine all the kinetic rates in terms of the experimentally accessible messenger RNA degradation rate
Inducing omni-temporality: product heritage appropriation in corporate heritage brand construction
No full textInternational audienceThis article advances knowledge on omni-temporality by looking at the processes by which a corporate brand may appropriate and valorise the heritage traits of a product brand. Set within the corporate and product brand dynamic, it presents the results of a qualitative study using case research on LVMH and Dom Pérignon. The study identifies how a younger corporate brand appropriates an older product brand’s heritage. Results contribute to a better understanding of the induction of omni-temporality, and of the development of a corporate heritage brand. They pave the way for a meritocratic view of corporate heritage as a status that can be acquired through managerial work
Une greffe qui ne prend pas : Quand le new public management s’attaque à la justice
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What are C-tactile afferents and how do they relate to “affective touch”?
No full textInternational audienceSince their initial discovery in cats, low-threshold C-fiber mechanoreceptors have become a central interest of scientists studying the affective aspects of touch. Their pursuit in humans, here termed C-tactile (CT) afferents, has led to the establishment of a research field referred to as “affective touch”, which is differentiated from “discriminative touch”. Presently, we review these developments based on an automated semantic analysis of more than 1000 published abstracts as well as empirical evidence and the solicited opinions of leading experts in the field. Our review provides a historical perspective and update of CT research, it reflects on the meaning of “affective touch”, and discusses how current insights challenge established views on the relation between CTs and affective touch. We conclude that CTs support gentle, affective touch, but that not every affective touch experience relies on CTs or must necessarily be pleasant. Moreover, we speculate that currently underappreciated aspects of CT signaling will prove relevant for the manner in which these unique fibers support how humans connect both physically and emotionally
