361 research outputs found
Participation paysanne, discours et pratiques : quelques réflexions sur le texte de J.P. Chauveau
Structural, static and dynamic magnetic properties of CoMnGe thin films on a sapphire a-plane substrate
Magnetic properties of CoMnGe thin films of different thicknesses (13, 34,
55, 83, 100 and 200 nm), grown by RF sputtering at 400{\deg}C on single crystal
sapphire substrates, were studied using vibrating sample magnetometry (VSM) and
conventional or micro-strip line (MS) ferromagnetic resonance (FMR). Their
behavior is described assuming a magnetic energy density showing twofold and
fourfold in-plane anisotropies with some misalignment between their principal
directions. For all the samples, the easy axis of the fourfold anisotropy is
parallel to the c-axis of the substrate while the direction of the twofold
anisotropy easy axis varies from sample to sample and seems to be strongly
influenced by the growth conditions. Its direction is most probably monitored
by the slight unavoidable angle of miscut the Al2O3 substrate. The twofold
in-plane anisotropy field is almost temperature independent, in contrast with
the fourfold field which is a decreasing function of the temperature. Finally,
we study the frequency dependence of the observed line-width of the resonant
mode and we conclude to a typical Gilbert damping constant of 0.0065 for the
55-nm-thick film.Comment: 7 pages, 7 figures, To be published (Journal of Applied Physics
Vitamin D, a modulator of musculoskeletal health in chronic kidney disease
The spectrum of activity of vitamin D goes beyond calcium and bone homeostasis, and growing evidence suggests that vitamin
D contributes to maintain musculoskeletal health in healthy subjects as well as in patients with chronic kidney disease (CKD),
who display the combination of bone metabolism disorder, muscle wasting, and weakness. Here, we review how vitamin D
represents a pathway in which bone and muscle may interact. In vitro studies have confirmed that the vitamin D receptor
is present on muscle, describing the mechanisms whereby vitamin D directly affects skeletal muscle. These include genomic
and nonâgenomic (rapid) effects, regulating cellular differentiation and proliferation. Observational studies have shown that
circulating 25âhydroxyvitamin D levels correlate with the clinical symptoms and muscle morphological changes observed in
CKD patients. Vitamin D deficiency has been linked to low bone formation rate and bone mineral density, with an increased
risk of skeletal fractures. The impact of low vitamin D status on skeletal muscle may also affect muscle metabolic pathways,
including its sensitivity to insulin. Although some interventional studies have shown that vitamin D may improve physical
performance and protect against the development of histological and radiological signs of hyperparathyroidism, evidence is
still insufficient to draw definitive conclusions
Forms and Frames: Mind, Morality, and Trust in Robots across Prototypical Interactions
People often engage human-interaction schemas in human-robot interactions, so notions of prototypicality are useful in examining how interactionsâ formal features shape perceptions of social robots. We argue for a typology of three higher-order interaction forms (social, task, play) comprising identifiable-but-variable patterns in agents, content, structures, outcomes, context, norms. From that ground, we examined whether participantsâ judgments about a social robot (mind, morality, and trust perceptions) differed across prototypical interactions. Findings indicate interaction forms somewhat influence trust but not mind or morality evaluations. However, how participants perceived interactions (independent of form) were more impactful. In particular, perceived task interactions fostered functional trust, while perceived play interactions fostered moral trust and attitude shift over time. Hence, prototypicality in interactions should not consider formal properties alone but must also consider how people perceive interactions according to prototypical frames
Accuracy of Singularity Expansion Method in Time and Frequency Domains to Characterize Antennas in Presence of Noise
International audienceIn this paper, the accuracy of the singularity expansion method (SEM) used for antenna characterization is investigated. A well-known limitation of the SEM is that pole extraction is very sensitive to noise. A comparison between two main methods of pole extraction is presented. The matrix pencil (MP) method and the Cauchy's method are used to extract poles from the radiated fields of a dipole antenna and two bowtie antennas. Results are presented for simulated fields, and the robustness to a white Gaussian noise is also analyzed. We show that the MP method allows working with lower SNR than Cauchy's method and is more accurate for field reconstruction
Window increasing technique to discriminate mathematical and physical resonant poles extracted from antenna response
International audienceThis letter presents a new approach called window increasing technique (WIT) to discriminate mathematical and physical poles extracted from a noisy antenna response. The principle of the WIT is to apply a pole extraction method on several windows of the response and then to observe the stability of the extracted poles. In order to compare the WIT to the classical window moving technique (WMT), we apply these two techniques on the electric far field backscattered by a dipole antenna. We show that, in presence of noise, the WIT allows finding more physical poles with a good accuracy than the WMT
What impacts of climate change on surface water in France by 2070? Results of the Explore2070 project in metropolitan France and overseas departments
International audienceLes questions relatives Ă la disponibilitĂ© et Ă la gestion de l'eau concentreront l'essentiel des mesures d'adaptation qui seront prises dans les dĂ©cennies Ă venir pour faire face aux consĂ©quences des changements climatiques. Ces mesures devront Ă©galement prendre en compte les Ă©volutions socio-Ă©conomiques, en termes de dĂ©mographie, d'amĂ©nagement du territoire et de politiques publiques (agriculture, Ă©nergie, transports, etc.). Il est dĂšs lors primordial pour les dĂ©cideurs et gestionnaires de quantifier les Ă©volutions socio-Ă©conomiques possibles, ainsi que le devenir de la ressource en eau et de sa variabilitĂ© temporelle et spatiale. C'est dans ce contexte que le projet Explore2070 avait pour objectif d'Ă©valuer les impacts possibles des changements climatiques et socio-Ă©conomiques futurs sur les grandes masses d'eau (surface, souterrain, littoral) et la biodiversitĂ©, en France mĂ©tropolitaine et sur les dĂ©partements d'Outre-mer (Guadeloupe, Guyane, Martinique et RĂ©union). PilotĂ© par le MinistĂšre de l'Ecologie (MEDDTL), ce projet a rassemblĂ© de nombreux bureaux d'Ă©tudes et instituts de recherche pour dresser un panorama gĂ©nĂ©ral des Ă©volutions Ă attendre Ă l'horizon 2070. Par son ampleur et la variĂ©tĂ© de ses objectifs, ce projet doit permettre de rĂ©pondre Ă de nombreuses questions des gestionnaires et de mieux apprĂ©cier les enjeux de ces Ă©volutions. Dans la suite, nous prĂ©sentons les travaux rĂ©alisĂ©s spĂ©cifiquement sur la quantification des Ă©volutions des eaux de surface. Nous dĂ©taillerons dans ce qui suit la dĂ©marche gĂ©nĂ©rale de modĂ©lisation proposĂ©e, la nature des rĂ©sultats obtenus, ainsi que la façon dont les incertitudes ont Ă©tĂ© quantifiĂ©es. Ce dernier point est indispensable pour aider Ă la prise de dĂ©cision dans un avenir incertain. / Water availability and water management will be the focus of most of the adaptation measures that will be taken in the next decades to face the consequences of climate change. These measures will have to account for the socio-economic evolutions, in terms of population size, town and country planning, as well as public policies (agriculture, energy, transports, etc.). It is therefore essential for decision makers and managers to be able to quantify the possible socio-economic evolutions together with the evolution of water resources and their temporal and spatial variability. In this context, the Explore2070 project aimed at evaluating the possible impacts of future climate and socio-economic changes on water bodies (surface water, groundwater and coastal water) and biodiversity, in metropolitan France and overseas departments (Guadeloupe, Martinique, French Guyana, and RĂ©union Island). The project was managed by the French Ministry of Ecology (MEDDTL) and gathered several consultancies and research institutes to establish a general overview of the expected evolutions by 2070. Through both the extent and the variety of the projectâs objectives, Explore2070 will provide answers to many questions raised by managers and better evaluate the stakes related to these evolutions. In the following, we present the work done specifically to quantify the evolution of surface water. The general modelling approach, the type of results and the way uncertainties were quantified are detailed. Uncertainty quantification is essential to help decision making in an uncertain future
How Tuning Interfaces Impacts the Dynamics and Structure of Polymer Nanocomposites Simultaneously
Fundamental understanding of macroscopic properties of polymer nanocomposites
(PNCs) remains difficult due to the complex interplay of microscopic dynamics
and structure, namely interfacial layer relaxations and three-dimensional
nanoparticle arrangements. The effect of surface modification by alkyl
methoxysilanes at different grafting densities has been studied in PNCs made of
poly(2-vinylpyridine) and spherical 20 nm silica nanoparticles (NPs). The
segmental dynamics has been probed by broadband dielectric spectroscopy, and
the filler structure by small-angle X-ray scattering and reverse Monte Carlo
simulations. By combining the particle configurations with the interfacial
layer properties, it is shown how surface modification tunes the attractive
polymer-particle interactions: bare NPs slow down the polymer interfacial layer
dynamics over a thickness of ca. 5 nm, while grafting screens these
interactions. Our analysis of interparticle spacing and segmental dynamics
provides unprecedented insight into the effect of surface modification on the
main characteristics of PNCs: particle interactions and polymer interfacial
layers
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