Multidisciplnary approach applied to activity analysis within a dynamic setting: driving light vehicles for postal delivery of mail and parcels

A complex activity different from personal driving, professional light vehicle driving is becoming increasingly important in the delivery/messaging sector faced with new consumption patterns. Sparsely studied, health risks other than road accidents were approached in an exploratory multidisciplinary study conducted in collaboration with the La Poste group. Its objective was to explore, in work situation, the different components of the mail/parcel delivery activity, and particularly the driving activity as a structuring part of the distribution activity. The methodological approach combining ergonomic analyses and a medical approach has revealed postural and psychological constraints as well as complaints mainly related to the characteristics of the distribution rounds. These findings contributed to the construction of an epidemiological study aimed to analyze risk factors related to driving light vehicles for postal delivery activities.Activité complexe différente de la conduite personnelle, la conduite professionnelle de véhicule léger prend une importance croissante dans le secteur de la livraison/messagerie confronté aux nouveaux modes de consommation. Peu étudiés, les risques pour la santé autres que les accidents de la route ont été approchés dans une étude exploratoire multidisciplinaire menée en collaboration avec le groupe La Poste. Son objectif a été d’explorer, en situation de travail, les différentes composantes de l’activité de distribution de courrier/colis, et particulièrement l’activité de conduite comme partie structurante de l’activité de distribution. La démarche méthodologique alliant des analyses ergonomiques et une approche médicale a mis en évidence des contraintes ainsi que des plaintes en relation principalement avec les caractéristiques des tournées de distribution. Ces résultats ont permis d’orienter la construction d’une étude épidémiologique visant à analyser les facteurs de risque spécifiques à la conduite de véhicule léger dans les activités de distribution.Actividad compleja diferente del manejo de un vehículo personal, la conducción profesional de vehículos ligeros es cada vez más importante en el sector de entrega/mensajería frente a nuevos patrones de consumo. Poco estudiados, los riesgos para la salud diferentes a los accidentes de tráfico se abordaron en un estudio exploratorio multidisciplinario realizado en colaboración con el grupo de servicios postales La Poste. El objetivo fue explorar, en situación de trabajo, los diferentes componentes de la actividad de entrega de correo/paquetería, y particularmente la actividad de conducción como una parte estructuradora de la actividad de distribución. El enfoque metodológico que combina el análisis ergonómico y un enfoque médico pusieron en evidencia las dificultades y las quejas relacionadas principalmente con las características de las rondas de distribución. Estos resultados permitieron orientar la construcción de un estudio epidemiológico destinado a analizar los factores de riesgo específicos en el manejo de vehículos livianos en actividades de distribución

Tubulin tyrosination regulates synaptic function and is disrupted in Alzheimer's disease

: Microtubules play fundamental roles in the maintenance of neuronal processes and in synaptic function and plasticity. While dynamic microtubules are mainly composed of tyrosinated tubulin, long-lived microtubules contain detyrosinated tubulin, suggesting that the tubulin tyrosination/detyrosination cycle is a key player in the maintenance of microtubule dynamics and neuronal homeostasis, conditions which go awry in neurodegenerative diseases. In the tyrosination/detyrosination cycle, the C-terminal tyrosine of α-tubulin is removed by tubulin carboxypeptidases and re-added by tubulin tyrosine ligase. Here we show that tubulin tyrosine ligase hemizygous mice exhibit decreased tyrosinated microtubules, reduced dendritic spine density, and both synaptic plasticity and memory deficits. We further report decreased tubulin tyrosine ligase expression in sporadic and familial Alzheimer's disease, and reduced microtubule dynamics in human neurons harboring the familial APP-V717I mutation. Finally, we show that synapses visited by dynamic microtubules are more resistant to oligomeric amyloid β peptide toxicity and that expression of tubulin tyrosine ligase, by restoring microtubule entry into spines, suppresses the loss of synapses induced by amyloid β peptide. Together, our results demonstrate that a balanced tyrosination/detyrosination tubulin cycle is necessary for the maintenance of synaptic plasticity, is protective against amyloid β peptide-induced synaptic damage, and that this balance is lost in Alzheimer's disease, providing evidence that defective tubulin retyrosination may contribute to circuit dysfunction during neurodegeneration in Alzheimer's disease

Refined physical parameters for Chariklo’s body and rings from stellar occultations observed between 2013 and 2020

Context. The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity. Aims. Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo. Methods. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and ring structure. Results. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3σ), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo's detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8-1.5+1.4, 135.2-2.8+1.4, and 99.1-2.7+5.4 km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris

The beta-beam decay ring design

The aim of the beta-beams is to produce highly energetic beams of pure electron neutrino and antineutrino, coming from β-decays of the 18Ne10+ and 6He2+, both at gamma = 100, directed towards experimental halls situated in the Fréjus tunnel. The high intensity ion beams are stored in a ring until the ions decay. Consequently, all the injected ions will be lost anywhere in the ring, generating a high level of irradiation. Since they come from the SPS, the ring circumference has to be a multiple of the SPS one. The straight sections must be as long as possible in order to maximize the useful neutrino flux. The straight section length is chosen to be about 36% of the circumference length, which imposes 1-km-long arcs. The bend field in the arcs is then achievable. The arc has been chosen as a2Pi phase advance insertion, which improves the optical properties (dynamic aperture and momentum acceptance) and allows the easy determination of the working point bythe optics of the straight sections

Loss management in the beta-beam decay ring

The aim of the beta-beams is to produce pure electron neutrino and anti-neutrino highly energetic beams, coming from β-decay of the 18Ne10+ and 6He2+, both at γ = 100, directed towards experimental halls situated in the Fréjus tunnel [1], [2]. The high intensity ion beams are stored in a ring, until the ions decay. Consequently, all the injected particles will be lost anywhere around the ring generating a high level of irradiation. In order to keep a constant neutrino flux, the losses due to the decay of the radioactive ions are compensated with regular injections. The new ion beam is then merged with the stored beam with a specific RF program [3]. We have to consider two sources of losses: – The β-decay products: their magnetic rigidity being different from the reference one, they are bent differently and lost. – The losses during the injection merging process. The first one needs a particular ring design in order to insert appropriate beam stoppers at the right place. The second one needs a specific collimation system which allows beam longitudinal halo cleaning between two successive injections

Les effets toxiques des rayonnements ionisants

Les sources de radiations (ALFA, BETA, GAMMA, neutroniques) auxquelles l'organisme humain est soumis sont d'origine naturelle ou artificielle et l'irradiation du corps humain peut avoir lieu soit par voie interne soit externe. Les rayonnements ionisants agissent à plusieurs niveaux de l'organisme humain, le principal niveau étant la molécule d'ADN. Les radiations ionisantes n'ont aucune spécificité, les effets sur l'organisme humain pouvant être : somatiques, génétiques ou héréditaires, tératogènes. Dans le cas d'une irradiation d'un être humain nous procédons au diagnostic et au traitement de la personne irradiée, cependant, pour diminuer l'incidence des atteintes on utilise la radioprotection. Le traitement en cas de besoin sera instauré en fonction du type d'irradiation.ROUEN-BU Médecine-Pharmacie (765402102) / SudocSudocFranceF

Finite element analysis of damage in ductile structures using a nonlocal model combined with a three-field formulation

International audienceSolving finite element problems involving elasto-plasticity coupled with damage softening faces two major difficulties: mesh dependence and volumetric locking. In this study, a specific finite element is proposed which allows to solve simultaneously both problems within the small strain framework. It combines a mixed treatment based on a three-field formulation (displacements, assumed pressure, and assumed dilatation) to solve the volumetric locking and a nonlocal implicit gradient-enhanced formulation to avoid localization of damage. Simulations on a double-notched specimen are presented which allow to compare the nonlocal formulation and the mixed nonlocal formulation. Triangular elements with quadratic shape functions for the displacements and linear shape functions for the assumed dilatation, assumed pressure, and nonlocal variable are used. First results show that the mixed nonlocal method regular