Les fonctions communicationnelles des systèmes médiatiques : conception et critères de choix

Dans le domaine éducatif, les médias ont été traditionnellement analysés et classés selon les langages naturels qu'ils supportaient (sons et images), les canaux de perception auxquels ils s'adressaient (audioscripto- visuels) ou leur mode de présentation. À partir de l'analyse des dispositifs médiatiques mis en oeuvre lors de trois expériences pédagogiques se proposant de rapprocher les institutions artistiques et scolaires afin de sensi- biliser les jeunes à la création artistique en relation avec leur environnement quotidien, on tente ici de dégager les principales fonctions communication- nelles qui devraient être prises en compte lors de l'élaboration de tout design pédagogique afin de sélectionner, voire de concevoir les systèmes médiatiques les plus adéquats à un projet pédagogique particulier.Within the field of education, media has been analysed and classified accord- ing to either the type of language transmitted (sound and images), the perception channels addressed (audio - or text-visual), or the means of presentation. The aim of the three teaching projects examined in this study was to bring together both artistic and educa- tional institutions in order to sensitize young people to focus on artistic creativity in their everyday lives. Based on an analysis of the practices implemented in these three projects, the authors attempt to describe the principal communication functions that should be considered in pedagogical design in order to select and elaborate media systems appropri- ate to a specific pedagogical project.En el sector de educacion, los medios de comunicaciôn han sido tradicional- mente analizados y clasificados segûn los lenguajes naturales que adoptan (sonidos e imâgenes), los canales de percepciôn a los cuales se dirigen (audio-scripto-visuales) o segûn sus modalidades de presentaciôn. Se desprenden aquî las principales funciones de comunicaciôn que deberîan ser consideradas durante la elaboraciôn de todo disefio pedagôgico con el fin de seleccionar, véase concebir los sistemas mediâticos mas adecua- dos para un proyecto pedagôgico especîfico. Esto se hace a partir del anâlisis de los dispos- itivos mediâticos utilizados durante las très experiencias pedagôgicas que pretenden acercar las instituciones artîsiticas y escolares con el fin de sensibilizar los jôvenes a la creaciôn artîstica en relaciôn a su ambiente cotidiano.Im Erziehungssektor werden die Media traditionellerweise nach den naturlichen Ausdrucksmitteln untersucht und eingestuft, die sie tragen (Ton und BiId), nach den Sinnen, auf die sie sien richten (Hôren - Lesen - Sehen), oder nach ihrer Darstellungsart. Ausgehend von der Analyse von mediatischen Hilfsmitteln, die bei drei pàdagogischen Versuchen verwendet wurden, welche die Kunstinstitutionen der Schule nàherbringen sollten, um die Jugendlichen zu kûnstlerisch schôpferischer Tâtigkeit im Zusammenhang mit ihrem Lebensmilieu anzuregen, will man hier die wesentlichen Kommunikationsfunktionen herausstellen, deren bei der Ausarbeitung aller pàdagogischen Muster Rechnung getragen werden mùsste, um die Auswahl, ja schon die Konzeption der am besten fur ein bestimmtes pàdagogisches Vorhaben geeigneten mediatischen Hilfsmittel zu erleichtern

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50$\mu$m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter $\alpha \geq 2$), the Brownian motion seems not to affect the cloud behavior

Postnatal odorant exposure induces peripheral olfactory plasticity at the cellular level

Mammalian olfactory sensory neurons (OSNs) form the primary elements of the olfactory system. Inserted in the olfactory mucosa lining of the nasal cavity, they are exposed to the environment and their lifespan is brief. Several reports say that OSNs are regularly regenerated during the entire life and that odorant environment affects the olfactory epithelium. However, little is known about the impact of the odorant environment on OSNs at the cellular level and more precisely in the context of early postnatal olfactory exposure. Here we exposed MOR23-green fluorescent protein (GFP) and M71-GFP mice to lyral or acetophenone, ligands for MOR23 or M71, respectively. Daily postnatal exposure to lyral induces plasticity in the population of OSNs expressing MOR23. Their density decreases after odorant exposure, whereas the amount of MOR23 mRNA and protein remain stable in the whole epithelium. Meanwhile, quantitative PCR indicates that each MOR23 neuron has higher levels of olfactory receptor transcripts and also expresses more CNGA2 and phosphodiesterase 1C, fundamental olfactory transduction pathway proteins. Transcript levels return to baseline after 4 weeks recovery. Patch-clamp recordings reveal that exposed MOR23 neurons respond to lyral with higher sensitivity and broader dynamic range while the responses' kinetics were faster. These effects are specific to the odorant-receptor pair lyral-MOR23: there was no effect of acetophenone on MOR23 neurons and no effect of acetophenone and lyral on the M71 population. Together, our results clearly demonstrate that OSNs undergo specific anatomical, molecular, and functional adaptation when chronically exposed to odorants in the early stage of life

Odor-Induced Neuronal Rhythms in the Olfactory Bulb Are Profoundly Modified in ob/ob Obese Mice

Leptin, the product of the Ob(Lep) gene, is a peptide hormone that plays a major role in maintaining the balance between food intake and energy expenditure. In the brain, leptin receptors are expressed by hypothalamic cells but also in the olfactory bulb, the first central structure coding for odors, suggesting a precise function of this hormone in odor-evoked activities. Although olfaction plays a key role in feeding behavior, the ability of the olfactory bulb to integrate the energy-related signal leptin is still missing. Therefore, we studied the fate of odor-induced activity in the olfactory bulb in the genetic context of leptin deficiency using the obese ob/ob mice. By means of an odor discrimination task with concomitant local field potential recordings, we showed that ob/ob mice perform better than wild-type (WT) mice in the early stage of the task. This behavioral gain of function was associated in parallel with profound changes in neuronal oscillations in the olfactory bulb. The distribution of the peaks in the gamma frequency range was shifted toward higher frequencies in ob/ob mice compared to WT mice before learning. More notably, beta oscillatory activity, which has been shown previously to be correlated with olfactory discrimination learning, was longer and stronger in expert ob/ob mice after learning. Since oscillations in the olfactory bulb emerge from mitral to granule cell interactions, our results suggest that cellular dynamics in the olfactory bulb are deeply modified in ob/ob mice in the context of olfactory learning

Carbapenemase-producing Enterobacteriaceae in hospital wastewater:a reservoir that may be unrelated to clinical isolates [star]

Summary Background: Carbapenemase-producing Enterobacteriaceae (CPE) are an emerging infection control problem in hospitals worldwide. Identifying carriers can help reduce potential spread and infections. Aim: To assess whether testing hospital wastewater for CPE can supplement patient based screening for infection prevention purposes in a hospital without a recognised endemic CPE problem. Methods: Wastewater collected from hospital pipework on 16 occasions during February-March 2014 was screened for CPE using chromID®CARBA agar and chromID®CPS agar with a 10 μg ertapenem disc and combination disc testing. MICs were determined using British Society for Antimicrobial Chemotherapy methodology and carbapenemase genes detected by PCR or wholegenome sequencing. Selected isolates were typed by PFGE. Findings: Suspected CPE were recovered from all 16 wastewater samples. Of 17 isolates sent to Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, six (four Citrobacter freundii and two Enterobacter cloacae complex) were New Delhi metallo–beta-lactamase (NDM) producers and the remaining 11 (six Klebsiella oxytoca and five Enterobacter cloacae complex), Guiana-Extended-Spectrum-5 (GES-5) producers, the first to be described in Enterobacteriaceae in the UK. The four NDM-producing C. freundii, two NDM-producing E. cloacae complex and 4/5 GES-5-producing E. cloacae complex were each indistinguishable isolates of the same three strains, whereas the six GES-5-producing K. oxytoca overall shared 79% similarity. Conclusion: CPE are readily isolated from hospital wastewater using simple culture methods. There are either undetected carriers of CPE excreting into the wastewater, or these CPE represent colonisation of the pipework. Surveillance of hospital wastewater for CPE does not appear helpful for infection control purposes

2018 MAX-C/ExoMars Mission: The Orleans Mars-Analogue Rock Collection for Instrument Testing

International audienceIn order to reply to the exobiological goals of the 2018 MAX-C/ExoMars mission, the Orléans-OSUC analogue rock collection and database contains well characterised Mars analogue rocks and minerals for use in instrument testing and in situ missions