Nous et les autres : l’égalité face au risque

S'appuyant sur une lecture ethnographique de figures mythiques, le présent article tente de mettre en lumière certaines rémanences dans la perception de l'Autre et ses associations avec l'Ailleurs porteur de menaces pour démontrer une hiérarchisation des usages et, par extension, des vies humaines en matière de prévention des risques naturels. Ainsi, l'homme de passage, campeur ou nomade, se trouve souvent relégué en marge de l'espace socialisé, dans des lieux « défortunés » soumis à des risques élevés de crues torrentielles. Cet article pose le problème fondamental de la confrontation des échelles de la nation et du terroir dans la gestion locale du territoire et, au-delà, de l'égalité des citoyens devant le risque.Supported by the networks of similarities and the sacred territories induced by analogical and symbolist geographies, this article attempts to shed light on certain remanences in the perception of the Other and its association with the threats of Elsewhere. It seeks to demonstrate a hierarchical organization of the customs and, by extension, of human lives in the prevention of natural hazards. It formulates the fundamental problems of the confrontation of the nation and native country scales in the local management of territory and beyond, of citizens' equality in the face of natural hazards

Les dragons de la crue

S'appuyant sur quelques légendes de dragons occidentaux et les cérémonies qui leur sont associées, l'auteur recherche, à travers la symbolique du serpent, la signification de cette image rémanente et propose une nouvelle interprétation : celle d'une image profane de l'eau vive destinée à illustrer le comportement de celle-ci et à entretenir la conscience de la crue au sein de la société, tout en exorcisant l'angoisse de cette dernière par la fête et le masque. En guise de conclusion, l'auteur pose la question du rôle des images, en marge des concepts et des théories scientifiques, dans la pédagogie de l'environnement et le rapport de l'homme au milieu.Through some legends of western dragons and the associated ceremonies, the author searches in the symbolic of the snake the significance of this image, in order to suggest a new interpretation: a profane image of the running water illustrating its mechanism and maintaining the conscience of the floods within society, while exorcising its anguish by the feast and the mask. In conclusion, the author points out the part of images, with the scientific concepts and theories, in the pedagogy of the environment and the relationship between man and the environment

Fast acoustic streaming in standing waves : Generation of an additional outer streaming cell

Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL > 1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes

IRM fonctionnelle chez le rat (défis méthodologiques)

L'imagerie par résonance magnétique fonctionnelle (IRMf ) permet de détecter sur le cerveau entier des activations neuronales en réponse à un stimulus, par le biais de l'observation des modifications hémodynamiques occasionnées. En particulier, l'IRMf est un outil de choix pour l'étude des mécanismes de la stimulation cérébrale profonde et de la stimulation du nerf vague qui sont encore mal connus. Cependant, cette technique n'est pas facilement utilisable chez l'homme en raison des problèmes de sécurité vis-à-vis de l'action des champs magnétiques intenses utilisés en IRM au niveau des électrodes implantées. Les développements méthodologiques chez l'animal sont donc nécessaires. L'objectif principal de cette thèse est l'étude des mécanismes à distance de la stimulation du système nerveux central et périphérique par IRMf chez le rat. Nous présentons dans un premier temps les séquences IRM rapides utilisées en IRMf, comme l'Echo-Planar Imaging multishot, permettant d'imager le cerveau entier en 1 à 2 secondes seulement, ainsi que les différents problèmes posés par l'utilisation de ces séquences, comme les artefacts de susceptibilité magnétique. Le couplage des séquences développées durant cette thèse avec des mesures électrophysiologiques a notamment permis l'imagerie des réseaux épileptiques chez le rat. Dans un second temps, nous développons les problèmes posés par la préparation animale, particulière en IRMf de par le fait que le couplage neurovasculaire doit être préservé sous anesthésie afin de préserver les activations neuronales. Après comparaison avec les anesthésies à l'isoflurane et la kétamine, nous avons déduit que la médétomidine constituait un anesthésique de choix pour l'IRMf du rongeur, et précisons le protocole de préparation animale utilisé pour l'imagerie. De plus, les électrodes utilisées en stimulation intracérébrale induisent des artefacts importants en imagerie, et des électrodes constituées de matériaux amagnétiques sont nécessaires. Nous expliquons pourquoi nous avons choisi des électrodes en carbone, et présentons le protocole de fabrication utilisé. Nous avons ensuite validé ces développements méthodologiques par des expériences d'IRMf de challenges hypercapniques et de stimulation de la patte chez le rat. Puis nous avons conduit une étude IRMf approfondie des mécanismes d'action de la stimulation du nerf vague, en s'intéressant à la distinction entre activations neuronales et effets cardiovasculaires confondants par modélisation causale dynamique. Nous présentons aussi des résultats en IRMf de la stimulation électrique intracérébrale chez le rat. Plusieurs cibles ont été stimulées (noyau géniculé dorso-latéral, gyrus dentelé, striatum et thalamus), et des activations ont été obtenues à distance de l'électrode, conformément aux connaissances actuelles sur les connexions neuroanatomiques de ces noyaux. Ainsi, nous avons mis au point et validé l'IRMf du rat et son application à la stimulation électrique du système nerveux périphérique et central.Functional magnetic resonance imaging (fMRI) can detect neuronal activations in the entire brain, in response to a stimulus, through the observation of subsequent hemodynamic changes. In particular, fMRI is a good tool for studying the mechanisms of deep brain stimulation and vagus nerve stimulation, which are still poorly understood. However, this technique is not readily usable in humans because of safety concerns towards the action of the strong magnetic fields used in MRI on implanted electrodes. Indeed, methodological developments in animals are needed. The main goal of this thesis is to study the mechanisms of central and peripheral nervous system stimulation in rats by fMRI. First, fast MRI sequences used in fMRI are exposed, such as multishot Echo-Planar Imaging, allowing to image the entire brain in a couple of seconds. Various imaging problems posed by these sequences, such as magnetic susceptibility artifacts, are also presented. These sequences, developed during this thesis, associated with electrophysiological measurements, allowed imaging of epileptic networks in the rat. Secondly, animal preparation is developped, as it is peculiar in fMRI : neuronal activations, as well as neurovascular coupling, must be preserved under anesthesia. Compared to anesthesia by isoflurane and ketamine, it was concluded that medetomidine was an anesthetic of choice for fMRI of the rodent, and the protocol used for animal preparation for imaging is specified. Furthermore, the electrodes used in deep brain stimulation induce significant artifacts in MRI images, and electrodes made of amagnetic materials are needed. Our choice of carbon electrodes is explained, and the manufacturing protocol used is exposed. These methodological developments were then validated in fMRI experiments of hypercapnic challenges and forepaw stimulation. Finally, an fMRI experiment studying mechanisms of action of vagus nerve stimulation was conducted, focusing on the distinction between neuronal activations and confounding cardiovascular effects by dynamic causal modeling. Also, results on fMRI of deep brain stimulation in rats are presented. Several targets were stimulated (dorsolateral geniculate nucleus, dentate gyrus, striatum and thalamus), and activations were obtained at a distance from the electrode. Results were in accordance with current knowledge on neuroanatomical connections of these nuclei. Thus, we developed and validated fMRI of the rat and its application to electrical stimulation of peripheral and central nervous system.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

pyActigraphy

Open-source python package for actigraphy data analysis. This package is meant to provide a comprehensive set of tools to: read actigraphy raw data files with various formats calculate typical wake/sleep cycle-related variables (ex: IS, IV, …) perform complex analyses (ex: FDA, SSA, HMM, …)Open-source python package for actigraphy data analysis

Identifying Neural Drivers with Functional MRI: An Electrophysiological Validation

Whether functional magnetic resonance imaging (fMRI) allows the identification of neural drivers remains an open question of particular importance to refine physiological and neuropsychological models of the brain, and/or to understand neurophysiopathology. Here, in a rat model of absence epilepsy showing spontaneous spike-and-wave discharges originating from the first somatosensory cortex (S1BF), we performed simultaneous electroencephalographic (EEG) and fMRI measurements, and subsequent intracerebral EEG (iEEG) recordings in regions strongly activated in fMRI (S1BF, thalamus, and striatum). fMRI connectivity was determined from fMRI time series directly and from hidden state variables using a measure of Granger causality and Dynamic Causal Modelling that relates synaptic activity to fMRI. fMRI connectivity was compared to directed functional coupling estimated from iEEG using asymmetry in generalised synchronisation metrics. The neural driver of spike-and-wave discharges was estimated in S1BF from iEEG, and from fMRI only when hemodynamic effects were explicitly removed. Functional connectivity analysis applied directly on fMRI signals failed because hemodynamics varied between regions, rendering temporal precedence irrelevant. This paper provides the first experimental substantiation of the theoretical possibility to improve interregional coupling estimation from hidden neural states of fMRI. As such, it has important implications for future studies on brain connectivity using functional neuroimaging

Near-infrared fluorescence imaging-guided surgery improves recurrence-free survival rate in novel orthotopic animal model of head and neck squamous cell carcinoma

International audienceBackground. Appropriate animal models are required to test novel therapeutics for head and neck squamous cell carcinoma (HNSCC) such as near-infrared (NIR) imaging-guided surgery. Methods. We developed an optimized animal model of orthotopic HNSCC (in female athymic NMRI (Naval Medical Research Institute) nude mice) with a prolonged survival time. Resection of the orthotopic tumors was performed 30 days after implantation with or without the aid of a minia-turized clinical grade NIR optical imaging device, after systemic administration of a fluorescent RGD-based probe that targets a v b 3 integrin. Results. NIR optical imaging-guided surgery increased the recurrence-free survival rate by 50% through the detection of fluorescent cancer residues as small as 185 mm; these fragments could remain unidentified if resection was performed exclusively under unaided visual guidance. Conclusion. NIR optical imaging-guided surgery showed an improved HNSCC tumor resection quality in our optimized orthotopic animal model

Uclacyanin Proteins Are Required for Lignified Nanodomain Formation within Casparian Strips

© 2020 The Author(s) Casparian strips (CSs) are cell wall modifications of vascular plants restricting extracellular free diffusion into and out of the vascular system [1]. This barrier plays a critical role in controlling the acquisition of nutrients and water necessary for normal plant development [2–5]. CSs are formed by the precise deposition of a band of lignin approximately 2 μm wide and 150 nm thick spanning the apoplastic space between adjacent endodermal cells [6, 7]. Here, we identified a copper-containing protein, Uclacyanin1 (UCC1), that is sub-compartmentalized within the CS. UCC1 forms a central CS nanodomain in comparison with other CS-located proteins that are found to be mainly accumulated at the periphery of the CS. We found that loss-of-function of two uclacyanins (UCC1 and UCC2) reduces lignification specifically in this central CS nanodomain, revealing a nano-compartmentalized machinery for lignin polymerization. This loss of lignification leads to increased endodermal permeability and, consequently, to a loss of mineral nutrient homeostasis