Auto-Associative models and generalized Principal Component Analysis

International audienceIn this communication, we propose auto-associative (AA) models to generalize Principal component analysis (PCA). AA models have been introduced in data analysis from a geometrical point of view. They are based on the approximation of the observations scatter-plot by a differentiable manifold. They are interpreted as Projection pursuit models adapted to the auto-associative case. Their theoretical properties are established and are shown to extend the PCA ones. An iterative algorithm of construction is proposed and its principle is illustrated both on simulated and real data from image analysis

Classification de Signaux Multidimensionnels Irrégulièrement Echantillonnés

National audienc

Classification de Signaux Multidimensionnels Irrégulièrement Echantillonnés

National audienc

Santé et sécurité du travail et formation professionnelle : Prochaine cible d’intérêt

Cette étude porte sur les événements accidentels associés à une blessure sans égard à sa gravité, survenus en cours de formation professionnelle, et sur les symptômes typiques d’une exposition professionnelle ressentis par les élèves. La population étudiée compte 327 élèves du programme d’entretien d’équipement motorisé. Tous les événements accidentels survenus en atelier à l’automne 2003 ont été documentés et un questionnaire sur des symptômes ressentis en lien avec l’exposition professionnelle en atelier de formation a été rempli par 213 élèves. Pour la période de septembre à décembre 2003, 72 événements ont été répertoriés (taux d’événements accidentels = 22 %). De ces derniers, 83,4 % sont survenus dans les spécialités mécanique automobile et carrosserie qui accueillaient 62,9 % des élèves inscrits, alors que les spécialités mécanique de véhicules lourds et engins de chantiers cumulaient 16,7 % des événements bien qu’elles comptaient 37 % des effectifs. Le questionnaire sur les symptômes a révélé que 11,3 % des répondants éprouvaient des douleurs au bas du dos et 16,0 % déclaraient avoir des problèmes cutanés qu’ils attribuaient, notamment, à leur exposition en atelier professionnel. Enfin, 29,6 % des répondants ont déclaré ressentir de la fatigue, avoir des difficultés de concentration ou des maux de tête sur une base régulière. Les résultats fournissent des indications importantes pour le Centre de formation professionnelle participant. La direction et les enseignants de ce CFP peuvent repérer des activités et des produits à risques et mettre de l’avant des mesures préventives appropriées. La nature exploratoire de l’étude ne permet pas de généraliser les résultats à l’ensemble des ateliers professionnels, mais témoigne de l’importance de documenter les questions de santé et de sécurité en milieu de formation professionnelle.This study investigates the accident events associated with an injury, without considering its severity, that occurred during vocational training, as well as the typical symptoms of the students’ occupational exposure. In the participating school, 327 students are enrolled in the motorized equipment maintenance program. All the accident events that occurred during the 2003 fall session were documented, and 213 students completed a questionnaire on the symptoms related to occupational exposure in a training workshop. Between September and December 2003, 72 accident events were documented (accident event rate of 22%). Of these, 83.4% occurred in automotive mechanics and body repair. These specialties accounted for 62.9% of the enrolled students. However, the heavy truck mechanics and heavy construction vehicle specialties accounted for 16.3% of the accident events while representing 37% of the population under study. The symptom questionnaire revealed that 11.3% of the respondents had low back pain and 16.0% had skin problems that they mainly attributed to their exposure in a vocational workshop. Finally, 29.6% reported that they regularly felt tired, had difficulty concentrating or had headaches. The results provide important indications about the situation prevailing in the participating professional school. Management and teachers from this vocational establishment can identify risky activities and hazardous products, as well as propose the appropriate preventive measures. Although the exploratory nature of the study prevents any generalization to all other vocational workshops, it highlights the importance of documenting the occupational health and safety question in vocational training environments.Este estudio se refiere a eventos accidentales asociados a una herida (sin tomar en cuenta su gravedad) que se produjo durante la formación profesional, y sobre los síntomas típicos de la exposición profesional sentidos por los alumnos. La población estudiada cuenta 327 estudiantes del programa de mantenimiento de equipo motorizado. Se documentaron todos los eventos accidentales que se produjeron en el taller durante el otoño 2003. Además, los estudiantes del programa fueron invitados a completar un cuestionario sobre los síntomas de problemas de salud relacionados con su exposición profesional en el taller de formación profesional. Este cuestionario fue respondido por 213 estudiantes. Durante el período de septiembre a diciembre 2003, ocurrieron 72 eventos (tasa de eventos accidentales = 22 %). De estos últimos, 83,4 % se produjeron en las especialidades de mecánica automóvil y carrocería que acogen 62,9 % de los alumnos inscritos. Las especialidades de mecánica de vehículos pesados y de maquinaria de construcción acumulaban 16,7 % de los eventos a pesar que cuentan con 37 % de los alumnos. El cuestionario sobre los síntomas reveló que 11,3 % de los participantes sentían dolores en la parte baja de la espalda y 16,0 % declaraban tener problemas cutáneos que atribuían particularmente a su exposición en los talleres de formación profesional. Finalmente, 29,6 % de los participantes dijeron sentir fatiga, tener dificultades de concentración y dolores de cabeza regularmente. Los resultados dan indicaciones importantes para el Centro de formación profesional participante. La dirección y los profesores de este CFP pueden identificar actividades y productos riesgosos y establecer las medidas preventivas apropiadas. La naturaleza exploratoria del estudio no permite generalizar los resultados al conjunto de los talleres de enseñanza profesional, pero atesta sobre la importancia de documentar las cuestiones de salud y de seguridad en los establecimientos de formación profesional

Use of CCD to Detect Terrestrial Cosmic Rays at Ground Level: Altitude vs. Underground Experiments, Modeling and Numerical Monte Carlo Simulation

International audienceIn this work, we used a commercial charge-coupled device (CCD) camera to detect and monitor terrestrial cosmic rays at ground level. Multi-site characterization has been performed at sea level (Marseille), underground (Modane Underground Laboratory) and at mountain altitude (Aiguille du Midi-Chamonix Mont-Blanc at +3,780 m of altitude) to separate the atmospheric and alpha particle emitter's contributions in the CCD response. An additional experiment at avionics altitude during a long-haul flight has been also conducted. Experiment results demonstrate the importance of the alpha contamination in the CCD response at ground level and its sensitivity to charged particles. Experimental data as a function of CCD orientation also suggests an anisotropy of the particle flux for which the device is sensitive. A complete computational modeling of the CCD imager has been conducted, based on a simplified 3D CCD architecture deduced from a reverse engineering study using electron microscopy and physico-chemical analysis. Monte Carlo simulations evidence the major contribution of low energy (below a few MeV) protons and muons in the CCD response. Comparison between experiments and simulation shows a good agreement at ground level, fully validated at avionics altitudes with a much higher particle flux and a different particle cocktail composition

Enjeux théoriques et pratiques du développement régional : 30 Ans de recherche au GRIR

Le trentième anniversaire du GRIR a été souligné au printemps 2013 par un colloque regroupant plusieurs chercheurs dans le domaine du développement local et régional. Cet ouvrage est le produit de leurs réflexions tant sur le plan théorique que pratique. Ce livre est articulé autour de trois axes : 1) la présentation des divers courants en développement régional, 2) des réflexions sur le passé et le présent des Premières Nations et 3) la présentation de cas concrets sur la prise en main du développement par les différents acteurs du territoire. Cet ouvrage est un outil permettant de constater le travail accompli en développement local et régional et de dégager des pistes de réflexion sur les avenues possibles de développement

Three years of harvest with the vector vortex coronagraph in the thermal infrared

For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 {\mu}m). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications.Comment: To appear in SPIE proceedings vol. 990

Root Microbiota in Primary and Secondary Apical Periodontitis

Apical periodontitis is an inflammatory disease of the dental periradicular tissues triggered by bacteria colonizing necrotic root canals. Primary apical periodontitis results from the microbial colonization of necrotic pulp tissues. Secondary apical periodontitis results from a persistent infection of incorrectly treated root canals. The aim of this study was to characterize the microbiota present in primary and secondary intraradicular infections associated with apical periodontitis using 16S rRNA gene amplicon sequencing. Teeth exhibiting apical periodontitis with or without root canal treatment were extracted after informed consent. From each tooth, the intraradicular content as well as a dentin sample (control) were collected and subjected to DNA extraction. PCR amplicons of the V3–V4 region of the bacterial 16S rRNA gene were pooled and sequenced (2 × 300) on an Illumina MiSeq instrument. The bioinformatics analysis pipeline included quality filtering, merging of forward and reverse reads, clustering of reads into operational taxonomic units (OTUs), removal of putative contaminant OTUs and assigning taxonomy. The most prevalent and abundant OTU in both dentin and root canal samples was assigned to anaerobic bacterium Fusobacterium nucleatum. Multivariate analysis showed clustering of microbiota by sample type (dentin vs. intraradicular content) and, in root canals, by pathology (primary vs. secondary infection). The proportions of Enterococcus faecalis and F. nucleatum were, respectively, higher and lower when comparing secondary to primary infected root canals. Co-occurrence network analysis provided evidence of microbial interactions specific to the infection type. The identification of bacterial taxa differentially abundant in primary and secondary intraradicular infections may provide the basis for targeted therapeutic approaches aimed at reducing the incidence of apical periodontitis