155 research outputs found

    Diagnostic of the Metal-Dielectric Interface in a Collective Oscillation of Electrons

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    Light reflected from a dielectric- metal interface describe the existence of resonant modes of the collective oscillation in electron density. The experimental configuration proposed by Otto and Kretschmann- Raether can be used to characterizes the optical properties of thin metallic films in contact with a dielectric medium. In far-field detection, the angular dependence of the reflectivity on Ag/ ambient air shows a sharp minimum beyond attenuated total reflection. At a wavelength, λ the geometric parameters influence strongly the angular resonance θSP. In the case of Ag, λ = 633.0 nm, at the optimal thickness, d = 50.8nm, a resonant coupling is reaches between incident photons and free electrons in the angular range 45° < θSP < 46°. The angular resonance is associated with the optical phenomenon of an energetic transfer predicted theoretically.Light reflected from a dielectric- metal interface describe the existence of resonant modes of the collective oscillation in electron density. The experimental configuration proposed by Otto and Kretschmann- Raether can be used to characterizes the optical properties of thin metallic films in contact with a dielectric medium. In far-field detection, the angular dependence of the reflectivity on Ag/ ambient air shows a sharp minimum beyond attenuated total reflection. At a wavelength, λ the geometric parameters influence strongly the angular resonance θSP. In the case of Ag, λ = 633.0 nm, at the optimal thickness, d = 50.8nm, a resonant coupling is reaches between incident photons and free electrons in the angular range 45° < θSP < 46°. The angular resonance is associated with the optical phenomenon of an energetic transfer predicted theoretically

    La grossesse chez les hémodialysées chroniques

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    La survenue d'une grossesse en hémodialyse chronique (HDC) est rare, mais depuis la description du premier cas par Confortini en 1971, plusieursobservations ont été rapportées. L'hémodialyse a considérablement  amélioré la fertilité de ces patientes. Nous rapportons l'expérience de  douze grossesses survenues entre 1999 et 2014, chez douze patientes d'âge médian 34 ans (22-44), en hémodialyse (HD) depuis 40 mois  (3-72), l'âge gestationnel moyen de diagnostic est de 16 semaines  d'aménorrhée, la grossesse était compliquée dans 50% des cas par un hydramnios. Le terme moyen est de 35 semaine d'aménorrhée (SA) et l'accouchement a été réalisé dans 90% des grossesses par voie basse. Le poids moyen des nouveau-nés est de 1800g. De telles grossesses sont à haut risque du fait de la fréquence des complications. Elles devraient être contrôlées par les équipes multidisciplinaires, et la consultation prénatal ne devrait pas être négligée. L'objectif de ce travail est de rapporter notre expérience concernant la survenue d'une grossesse chez les patientes dialysées et de la confronter aux données de la littérature

    Bifurcation and stability analysis of a two step model for monitoring anaerobic digestion processes

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    This paper deals with the equilibria and stability analysis of the two step anaerobic model initially proposed by [12] to describe the dynamical behavior of an anaerobic fixed-bed wastewater treatment process. In a first part, the model is analyzed: its equilibria and their stability are established considering qualitative properties of the kinetics. In a second part, it is shown that the overloading tolerance (denoted herein OT), a parameter proposed in [9] to monitor anaerobic processes on-line, may not be suitable for monitoring the system and even causes serious problems under certain functioning conditions. Based on the analysis results established in the first part, a modified OT is proposed and evaluated in simulation

    Analysis of optimal operation of a fed-batch emulsion copolymerization reactor used for production of particles with core–shell morphology

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    This paper was accepted for publication in the journal Computers and Chemical Engineering: http://www.sciencedirect.com/science/article/pii/S0098135414000532In this paper dynamic optimization of a lab-scale semi-batch emulsion copolymerization reactor for styrene and butyl acrylate in the presence of a chain transfer agent (CTA) is studied. The mathematical model of the process, previously developed and experimentally validated, is used to predict the glass transition temperature of produced polymer, the number and weight average molecular weights, the monomers global conversion, the particle size distribution, and the amount of residual monomers. The model is implemented within gPROMS environment for modeling and optimization. It is desired to compute feed rate profiles of pre-emulsioned monomers, inhibitor and CTA that will allow the production of polymer particles with prescribed core-shell morphology with high productivity. The results obtained for different operating conditions and various additional product specifications are presented. The resulting feeding profiles are analyzed from the perspective of the nature of emulsion polymerization process and some interesting conclusions are drawn

    Applying Sodium Profile with or without Ultrafiltration Profile Failed to Show Beneficial Effects on the Incidence of Intra- dialytic Hypotension in Susceptible Hemodilaysis Patients

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    Introduction: Intra-dialytic hypotension (IDH) is a common complication during hemodialysis (HD) treatment. Previous studies have reportedthat modulating dialysate sodium concentration combined or not with modulation of ultrafiltration (UF) rate may reduce the incidence of IDH. The aim of the present study was to evaluate the effect of sodium and UF profiles on the occurrence of intra-dialytic complications and dialysis quality.Methods: From a total of 64 patients, we selected 18 patients who suffered from recurrent IDH. Every patient received ten HD sessions utilizing each of the following treatments: (1) Control: constant sodium concentrationand UF rates. (2) Sodium and UF profiles: a linearly decreasing sodium concentration combined with a linearly decreasing UF rate. (3) Sodium profile:decreasing sodium concentration with constant UF rate.Results: Fourteen patients completed the study protocol. The incidence of IDH, mean inter-dialytic weight gain and the delivered dialysis dose were not different between the three treatments. However, symptomatic episodes of IDH were more commonand pre-dialysis systolic bloodpressure was higher during the second and third treatment modalities compared to controls. Isolated sodium profile was associated with more malaise and less achievement of target session duration compared to the other two treatments. Isolated sodium profile was associated withless achievement of target UF while combined sodium and UF profiles were associated with more achievement of target UF compared to controls.Conclusion: Our results indicate that sodium profile with or without UF profile does not have a beneficial effect on the incidence of IDH, achievement of target session duration or the delivered dialysis dose

    Tolerance to the Neuron-Specific Paraneoplastic HuD Antigen

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    Experiments dating back to the 1940's have led to the hypothesis that the brain is an immunologically privileged site, shielding its antigens from immune recognition. The paraneoplastic Hu syndrome provides a powerful paradigm for addressing this hypothesis; it is believed to develop because small cell lung cancers (SCLC) express the neuron-specific Hu protein. This leads to an Hu-specific tumor immune response that can develop into an autoimmune attack against neurons, presumably when immune privilege in the brain is breached. Interestingly, all SCLC express the onconeural HuD antigen, and clinically useful tumor immune responses can be detected in up to 20% of patients, yet the paraneoplastic neurologic syndrome is extremely rare. We found that HuD-specific CD8+ T cells are normally present in the mouse T cell repertoire, but are not expanded upon immunization, although they can be detected after in vitro expansion. In contrast, HuD-specific T cells could be directly activated in HuD null mice, without the need for in vitro expansion. Taken together, these results demonstrate robust tolerance to the neuronal HuD antigen in vivo, and suggest a re-evaluation of the current concept of immune privilege in the brain

    No evidence for circulating HuD-specific CD8+ T cells in patients with paraneoplastic neurological syndromes and Hu antibodies

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    Aim: In paraneoplastic neurological syndromes (PNS) associated with small cell lung cancer (SCLC) and Hu antibodies (Hu-PNS), Hu antigens expressed by the tumour hypothetically trigger an immune response that also reacts with Hu antigens in the nervous system, resulting in tumour suppression and neuronal damage. To gain more insight into the hypothesized CD8+T cell-mediated immune pathogenesis of these syndromes, we searched for circulating HuD-specific CD8+T cells in a large cohort of Hu-PNS patients and controls. Patients and methods: Blood was tested from 43 Hu-PNS patients, 31 Hu antibody negativ
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