Les pratiques informationnelles individuelles et collectives

Communication faite lors de la journée d\u27étude Thémat\u27IC 2007 "La maîtrise de l\u27information par les adultes : enjeux et méthodes", Strasbourg, mars 2007

Du capteur à l'image couleur

This chapter deals with the acquisition of colour images by mono-CCD colour cameras. These devices acquire only one colour component at each pixel through the CFA (Colour Filter Array) that covers the CCD sensor. A procedure - called demosaicing - is necessary to estimate the other two missing colour components at each pixel to obtain a colour image. A mathematical formalization for demosaicing is proposed, before we present some of the methods in the demosaicing literature, as well as the post-processing algorithms to correct the estimated images. We then present objective criteria for the quality evaluation of colour images, and apply them to estimated images to draw up conclusions about the selection of a demosaicing method. At last, we examine why and how white balancing is required and implemented to provide images faithfull to the observed scene under varying illumination conditions

PDB8 TYPE-2 DIABETES AND BODY MASS INDEX (BMI):WHAT CAN WE LEARN FROM A LONGITUDINAL DATABASE STUDY?

Farrando, Jordi;Febles, Maria Dolors ;Henrich, Jordi;Tarrasó, Olga ;Fuertes, J.C.;Pérez, S

Bolidomonas: a new genus with two species belonging to a new algal class, the Bolidophyceae (Heterokonta) 1.

International audienceA new algal class, the Bolidophyceae (Heterokonta), is described from one genus, Bolidomonas, gen, nov., and two species, Bolidomonas pacifica, sp, nov and Bolidomonas mediterranea, sp, nov., isolated from the equatorial Pacific Ocean and the Mediterranean Sea, respectively. Both species are approximately 1.2 mu m in diameter and have two unequal flagella; the longer flagellum bears tubular hairs, whereas the shorter is smooth. The flagellar basal apparatus is restricted to two basal bodies, and there is no transitional helix. Cells are naked, devoid of walls or siliceous structures. The internal cellular organization is simple with a single plastid containing a ring genophore and a girdle lamella, one mitochondrion with tubular cristae, and one Golgi apparatus close to the basal bodies. The Mediterranean and the Pacific species differ in the insertion angle between their flagella and their pattern of swimming, these differences possibly being linked to each other. Analyses of the SSU rDNA gene place the two strains as a sister group to the diatoms, Moreover, pigment analyses confirm this position, as fucoxanthin is found as the major carotenoid in both lineages. These data strongly suggest that the ancestral heterokont that gave rise to the diatom lineage was probably a biflagellated unicell

L'utilisation des moteurs de recherche par les jeunes : Impact des connaissances du domaine et des connaissances procédurales sur les stratégies d'exploration visuelle

International audienceDans une expérimentation conduite avec 53 élèves de CM2 utilisant la technique de l'oculométrie, nous tentons de mieux comprendre les stratégies d'exploration visuelle utilisées par de très jeunes usagers lors d'une tâche de recherche d'information sur le Web. Plus précisément, notre étude vise d'une part, à déterminer si plusieurs types de stratégies d'exploration visuelle d'une page de résultats proposés par un moteur de recherche (ou SERP) peuvent être déterminés et d'autre part, si des facteurs psychologiques (ici, les connaissances du domaine et les connaissances procédurales) peuvent influencer ces stratégies. Nos résultats ont principalement montré d'une part, que quatre stratégies d'exploration visuelle peuvent effectivement être distinguées et d'autre part, que le niveau de connaissances procédurales influence ces mêmes stratégies

Immersive Interfaces for Engagement and Learning: Cognitive Implications

International audienceImmersive Virtual Environments are distinct from other types of multimedia learning environments. But, if immersion defined the subjective impression that one is participating in a comprehensive and a realistic experience, immersive-ness is generally defined only from a systemic point of view (e.g., capacity to track users' movements, facial expressions and gestures, quality of appearance, combination of multi-sensory information, design of the virtual world). Moreover, nowadays, it does not exist a robust theoretical framework to describe and to predict immersive-ness from a user-point of view. So this paper is aiming to assume that (a) immersive-ness should be defined from a cognitive user point of view, and that (b) the cognitive architecture called MHP/RT (for Model Human Processor with Realtime Constraints) is relevant to understand and to predict immersive-ness. After a presentation of the MHP/RT model and the distributed memory system related to conscious and unconscious processes, we present the conditions necessary to produce an "immersive experience" for the user, and a case study is described as an example. Theoretical and method-ological perspectives are discussed

Amyloid Precursor-Like Protein 2 deletion-induced retinal synaptopathy related to congenital stationary night blindness: structural, functional and molecular characteristics.

Amyloid precursor protein knockout mice (APP-KO) have impaired differentiation of amacrine and horizontal cells. APP is part of a gene family and its paralogue amyloid precursor-like protein 2 (APLP2) has both shared as well as distinct expression patterns to APP, including in the retina. Given the impact of APP in the retina we investigated how APLP2 expression affected the retina using APLP2 knockout mice (APLP2-KO). Using histology, morphometric analysis with noninvasive imaging technique and electron microscopy, we showed that APLP2-KO retina displayed abnormal formation of the outer synaptic layer, accompanied with greatly impaired photoreceptor ribbon synapses in adults. Moreover, APLP2-KO displayed a significant decease in ON-bipolar, rod bipolar and type 2 OFF-cone bipolar cells (36, 21 and 63 %, respectively). Reduction of the number of bipolar cells was accompanied with disrupted dendrites, reduced expression of metabotropic glutamate receptor 6 at the dendritic tips and alteration of axon terminals in the OFF laminae of the inner plexiform layer. In contrast, the APP-KO photoreceptor ribbon synapses and bipolar cells were intact. The APLP2-KO retina displayed numerous phenotypic similarities with the congenital stationary night blindness, a non-progressive retinal degeneration disease characterized by the loss of night vision. The pathological phenotypes in the APLP2-KO mouse correlated to altered transcription of genes involved in pre- and postsynatic structure/function, including CACNA1F, GRM6, TRMP1 and Gα0, and a normal scotopic a-wave electroretinogram amplitude, markedly reduced scotopic electroretinogram b-wave and modestly reduced photopic cone response. This confirmed the impaired function of the photoreceptor ribbon synapses and retinal bipolar cells, as is also observed in congenital stationary night blindness. Since congenital stationary night blindness present at birth, we extended our analysis to retinal differentiation and showed impaired differentiation of different bipolar cell subtypes and an altered temporal sequence of development from OFF to ON laminae in the inner plexiform layer. This was associated with the altered expression patterns of bipolar cell generation and differentiation factors, including MATH3, CHX10, VSX1 and OTX2. These findings demonstrate that APLP2 couples retina development and synaptic genes and present the first evidence that APLP2 expression may be linked to synaptic disease

Immersive Interfaces for Engagement and Learning: Cognitive Implications

International audienceImmersive Virtual Environments are distinct from other types of multimedia learning environments. But, if immersion defined the subjective impression that one is participating in a comprehensive and a realistic experience, immersive-ness is generally defined only from a systemic point of view (e.g., capacity to track users' movements, facial expressions and gestures, quality of appearance, combination of multi-sensory information, design of the virtual world). Moreover, nowadays , it does not exist a robust theoretical framework to describe and to predict immersive-ness from a user-point of view. So this paper is aiming to assume that (a) immersive-ness should be defined from a cognitive user point of view, and that (b) the cognitive architecture called MHP/RT (for Model Human Processor with Realtime Constraints) is relevant to understand and to predict immersive-ness. After a presentation of the MHP/RT model and the distributed memory system related to conscious and unconscious processes , we present the conditions necessary to produce an " immersive experience " for the user, and a case study is described as an example. Theoretical and methodological perspectives are discussed

Elderly People as Web Seekers: Needs, Strategies and Difficulties

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