A Parametric Replay-Based Framework for Underwater Acoustic Communication Channel Simulation

International audienceThis paper lays the foundation of an underwater acoustic channel simulation methodology that is halfway between parametric modeling and stochastic replay of at-sea measurements of channel impulse responses. The motivation behind this approach is to extend the scope of use of replay-based methods by allowing some parameterization of the channel properties while complying with some level of realism. Based on a relative entropy minimization between the original channel impulse response and the simulated one, the idea is to deliberately distort the original channel statistics in order to meet some specified constraints

Construire le sens d’apprendre dans la confrontation à l’altérité

Pour de nombreux élèves massivement issus des classes populaires l’école est un lieu étrange, voire étranger, qu’ils refusent souvent et auquel ils s’opposent car enfermés dans des logiques d’échec qui n’ont pourtant aucun caractère de fatalité. En effet, lorsque le travail scolaire fait sens, lorsque le regard porté sur eux les convainc de leurs capacités, lorsqu’ils sont mis en situation de réfléchir, imaginer ou inventer, ils parviennent alors à se mobiliser. Leur engagement se trouve facilité par des pratiques pédagogiques qui rendent lisibles les attendus scolaires, dotent tous les élèves des outils intellectuels requis par l’école, leur propose des contenus d’apprentissage qui provoquent leur curiosité et les ouvre à une culture partagée.School is a strange, if not foreign place to many working-class pupils who often reject it because they experience failure, which however is not inevitable. When school work makes sense, when they are convinced of their capacities and when they are given the opportunity to think, imagine, or invent, they can become committed. Their commitment is eased by teaching practices that make school expectations understandable, equip all pupils with the intellectual tools required by the school system, and offer learning contents that rouse their curiosity and opens them to shared culture

Achievable Rates of Underwater Acoustic OFDM Systems over Highly Dispersive Channels

International audienceUnlike the capacity of other channels, the capacity of the shallow water UAC channel has been seldomly addressed. Motivated by recent results in information theory, this paper investigates achievable rates of underwater acoustic OFDM systems. We consider channels where time and frequency dispersion is high enough that (i) neither the transmitter nor the receiver can have a priori knowledge of the channel state information, and (ii) intersymbol/intercarrier interference (ISI/ICI) cannot be neglected in the information theoretic treatment

Long term GP opinions and involvement after a consultation-liaison intervention for mental health problems

<p>Abstract</p> <p>Background</p> <p>Shared Mental Health care between Psychiatry and Primary care has been developed to improve the care of common mental health problems but has not hitherto been adequately evaluated. The present study evaluated a consultation-liaison intervention with two objectives: to explore long-term GP opinions (relating to impact on their management and on patient medical outcome) and to determine the secondary referral rate, after a sufficient time lapse following the intervention to reflect a "real-world" primary care setting.</p> <p>Methods</p> <p>All the 139 collaborating GPs (response rate: 84.9%) were invited two years after the intervention to complete a retrospective telephone survey for each patient (181 patients; response rate: 69.6%).</p> <p>Results</p> <p>91.2% of GPs evaluated effects as positive for primary care management (mainly as support) and 58.9% noted positive effects for patient medical outcome. Two years post-intervention, management was shared care for 79.7% of patients (the GP as the psychiatric care provider) and care by a psychiatrist for 20.3% patients. Secondary referral occurred finally in 44.2% of cases.</p> <p>Conclusion</p> <p>The intervention supported GP partners in their management of patients with common mental health problems. Further studies are required on the appropriateness of the care provider.</p

Lock-in detection using a cryogenic low noise looped current preamplifier for the readout of resistive bolometers

We implemented a low noise current preamplifier for the readout of resistive bolometers. We tested the apparatus on thermometer resistances ranging from 10 Ohm to 500 Mohm. The use of current preamplifier overcomes constraints introduced by the readout time constant due to the thermometer resistance and the input capacitance. Using cold JFETs, this preamplifier board is shown to have very low noise: the Johnson noise of the source resistor (1 fA/Hz1/2) dominated in our noise measurements. We also implemented a lock-in chain using this preamplifier. Because of fast risetime, compensation of the phase shift may be unnecessary. If implemented, no tuning is necessary when the sensor impedance changes. Transients are very short, and thus low-passing or sampling of the signal is simplified. In case of spurious noise, the modulation frequency can be chosen in a much wider frequency range, without requiring a new calibration of the apparatus.Comment: 18 pages, 7 figures, Accepted in NIM

Intercomparison of Permittivity Measurement Techniques for Ferroelectric Thin Layers

International audienceThe dielectric properties of a KTa0.65Nb0.35O3 (KTN) ferroelectric composition for a submicronic thin layer were measured in the microwave domain using different electromagnetic characterization methods. Complementary experimental techniques (broadband methods versus resonant techniques, waveguide versus transmission line) and complementary data processing procedures (quasi-static theoretical approaches versus full-wave analysis) were selected to investigate the best way to characterize ferroelectric thin films. The measured data obtained from the cylindrical resonant cavity method, the experimental method that showed the least sources of uncertainty, were taken as reference values for comparisons with results obtained using broadband techniques. The error analysis on the methods used is discussed with regard to the respective domains of validity for each method; this enabled us to identify the best experimental approach for obtaining an accurate determination of the microwave dielectric properties of ferroelectric thin layers

Functional muscle impairment in facioscapulohumeral muscular dystrophy is correlated with oxidative stress and mitochondrial dysfunction

International audienceFacioscapulohumeral muscular dystrophy (FSHD),the most frequent muscular dystrophy, is an autosomal dominant disease. In most individuals with FSHD, symptoms are restricted to muscles of the face, arms, legs, and trunk. FSHD is genetically linked to contractions of the D4Z4 repeat array causing activation of several genes.One of these maps in the repeat itself and expresses the DUX4 (the double homeobox 4) transcription factor causing a gene deregulation cascade. In addition, analyses of the RNA or protein expression profiles in muscle have indicated deregulations in the oxidative stress response. Since oxidative stress affects peripheral muscle function, we investigated mitochondrial function and oxidative stress in skeletal muscle biopsies and blood samples from patients with FSHD and age-matched healthy controls, and evaluated their association with physical performances.We show that specifically, oxidative stress (lipid peroxidation and protein carbonylation), oxidative damage (lipofuscin accumulation), and antioxidant enzymes (catalase, copper–zinc-dependent super- oxide dismutase, and glutathione reductase) were higher in FSHD than in control muscles. FSHD muscles also presented abnormal mitochondrial function (decreased cytochrome c oxidase activity and reduced ATP synthesis). In addition, the ratio between reduced (GSH) and oxidized glutathione (GSSG) was strongly decreased in all FSHD blood samples as a consequence of GSSG accumulation. Patients with FSHD also had reduced systemic antioxidative response molecules, such as low levels of zinc (a SOD cofactor), selenium (a GPx cofactor involved in the elimination of lipid peroxides), and vitamin C. Half of them had a low ratio of gamma/alpha tocopherol and higher ferritin concentrations. Both systemic oxidative stress and mitochondrial dysfunction were correlated with functional muscle impairment. Mitochondrial ATP production was significantly correlated with both quadriceps endurance (TLimQ) and maximal voluntary contraction (MVCQ) values (rho¼0.79, P¼0.003; rho¼0.62, P¼0.05, respectively). The plasma concentration of oxidized glutathione was negatively correlated with the TLimQ, MVCQ values, and the 2-min walk distance (MWT) values (rho¼0.60, P¼0.03; rho¼0.56, P¼0.04; rho¼0.93, Po0.0001, respectively). Our data characterized oxidative stress in patients with FSHD and demonstrated a correlation with their peripheral skeletal muscle dysfunction. They suggest that antioxidants that might modulate or delay oxidative insult maybe useful in maintaining FSHD muscle functions

Delivery Site of Perivascular Endothelial Cell Matrices Determines Control of Stenosis in a Porcine Femoral Stent Model

PURPOSE: High restenosis rates are a major limitation of peripheral interventions. Endothelial cells, grown within gelatin matrices and implanted onto the adventitia of injured vessels, inhibit stenosis in experimental models. To determine if this technology could be adapted for minimally invasive procedures, we compared the effects of cells in an implantable sponge to an injectable formulation and investigated the importance of delivery site in a stent model. MATERIALS AND METHODS: Stents were implanted in the femoral arteries of 30 pigs followed by perivascular implantation of sponges or injection of particles containing allogeneic endothelial cells. Controls received acellular matrices or nothing. The effects of delivery site were assessed by injecting cellular matrices into or adjacent to the perivascular tissue, or into the neighboring muscle. Animals were sacrificed after 28 days. Pre-sacrifice angiograms and tissue sections were evaluated for stenosis. RESULTS: Arteries treated with cellular matrices had a 55 – 63% decrease in angiographic stenosis (P<0.05) and a 38 – 43% reduction (P<0.05) in histologic stenoses compared to controls. Intimal area was greatest when cellular matrices were delivered into the muscle (6.35 ± 0.95 mm2) compared to into or adjacent to the perivascular tissue (4.05 ± 0.56 mm2 and 4.73 ± 0.53 mm2, respectively, P < 0.05). CONCLUSIONS: Perivascular endothelial-cell matrices reduced stenosis after stent-induced injury. The effects were not dependent on the formulation but appeared to be dependent upon delivery site. Minimally invasive injections of endothelial-cell matrices to the adventitia of arteries following peripheral interventions may decrease restenosis rates.National Institutes of Health (U.S.) (Grant GM 49039

Hypovitaminosis D is associated with depression and anxiety in schizophrenia: results from the national FACE-SZ cohort. Running title: hypovitaminosis D, depression and anxiety in schizophrenia

International audienceBackground. Guidelines have been edited for the treatment of schizophrenia (SZ) and bipola