4,404 research outputs found

    A modal model for diffraction gratings

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    A description of an algorithm for a rather general modal grating calculation is presented. Arbitrary profiles, depth, and permittivity are allowed. Gratings built up from sub-gratings are allowed, as are coatings on the sidewalls of lines, and arbitrary complex structure. Conical angles and good conductors are supported

    Effect of annealing on the superconducting properties of a-Nb(x)Si(1-x) thin films

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    a-Nb(x)Si(1-x) thin films with thicknesses down to 25 {\AA} have been structurally characterized by TEM (Transmission Electron Microscopy) measurements. As-deposited or annealed films are shown to be continuous and homogeneous in composition and thickness, up to an annealing temperature of 500{\deg}C. We have carried out low temperature transport measurements on these films close to the superconductor-to-insulator transition (SIT), and shown a qualitative difference between the effect of annealing or composition, and a reduction of the film thickness on the superconducting properties of a-NbSi. These results question the pertinence of the sheet resistance R_square as the relevant parameter to describe the SIT.Comment: 9 pages, 12 figure

    QS-21 Adjuvant: Laboratory-Scale Purification Method and Formulation Into Liposomes.

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    QS-21, a saponin extracted from the tree Quillaja saponaria Molina, is a vaccine adjuvant which has been shown to elicit robust antibody and cell-mediated immune responses in a variety of preclinical and clinical studies [1]. Its purification from the natural source is a lengthy and difficult process. The commercially available saponin mixture Quil-A® is a fraction of the bark extract containing a variety of saponins, including QS-21. In order to facilitate access to QS-21 at laboratory-scale amounts, we propose here a method of purification of QS-21 starting from Quil-A®. In addition, we describe a protocol to appropriately formulate QS-21 into cholesterol-containing, neutral liposomes which are known to decrease QS-21's hemolytic activity while retaining the adjuvant effect. Methods for the physicochemical characterization of purified QS-21 and of the QS-21/liposome formulations are also described

    A randomized trial of brief intervention strategies in patients with alcohol-related facial trauma as a result of interpersonal violence

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    Facial trauma is associated with male gender, low socioeconomic status, alcohol misuse, and violence. Brief intervention (BI) for alcohol is effective at reducing consumption in patients presenting with facial trauma. Singlesession control of violence for angry impulsive drinkers(SS-COVAID) is a new intervention that attempts to address alcohol-related violence. This study assessed the effect of SS-COVAID and BI on drinking and aggression in facial trauma patients. Male facial trauma patients who sustained their injuries as a result of interpersonal violence while drinking and who had Alcohol Use Disorders Identification Test (AUDIT) scores of ≥8 were randomized to either BI or SS-COVAID. Patients were followed up at six and 12 months, and drinking and aggression outcomes were analyzed. One hundred ninety-nine patients entered the trial, and 187 were included in the analysis. Of these, 165 (89%) considered themselves to be victims, 92 (51%) had sustained a previous alcohol-related injury, and 28 (15%) had previous convictions for violence. Both interventions resulted in a significant decrease in negative drinking outcomes over 12 months of follow-up (p<0.001). Neither intervention had a significant effect on aggression scores, nor was there a significant difference between interventions in terms of either outcome. Both SS-COVAID and BI had a significant effect on drinking variables in this patient cohort. No effect on aggressionwas seen despite the fact that SS-COVAID specifically addresses the relationship between alcohol and violence. One reason for this may be that the facial trauma patients in this study considered themselves to be victims rather than aggressors. Another possibility is that, while BI may successfully address lifestyle factors such as hazardous or harmful drinking, it may not be effective in modifying personality traits such as aggression

    The puzzle of the soft X-ray excess in AGN: absorption or reflection?

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    The 2-10 keV continuum of AGN is generally well represented by a single power law. However, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the ''soft X-ray excess''. Until now this soft X-ray excess was attributed, either to reflection of the hard X-ray source by the accretion disk, or to the presence of an additional comptonizing medium, giving a steep spectrum. An alternative solution proposed by Gierlinski and Done (2004) is that a single power law well represents both the soft and the hard X-ray emission and the impression of the soft X-ray excess is due to absorption of a primary power law by a relativistic wind. We examine the advantages and drawbacks of reflection versus absorption models, and we conclude that the observed spectra can be well modeled, either by absorption (for a strong excess), or by reflection (for a weak excess). However the physical conditions required by the absorption models do not seem very realistic: we would prefer an ''hybrid model''.Comment: 4 pages, 3 figures, abstracts SF2A-2005, published by EDP-Sciences Conference Serie

    Dynamical quantum phase transition of a two-component Bose-Einstein condensate in an optical lattice

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    We study dynamics of a two-component Bose-Einstein condensate where the two components are coupled via an optical lattice. In particular, we focus on the dynamics as one drives the system through a critical point of a first order phase transition characterized by a jump in the internal populations. Solving the time-dependent Gross-Pitaevskii equation, we analyze; breakdown of adiabaticity, impact of non-linear atom-atom scattering, and the role of a harmonic trapping potential. Our findings demonstrate that the phase transition is resilient to both contact interaction between atoms and external trapping confinement.Comment: 8 pages, 8 figure

    Derivation of a tasselled cap transformation based on Landsat 7 at-satellite reflectance

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    A new tasselled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study

    Derivation of a tasselled cap transformation based on Landsat 7 at-satellite reflectance

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    A new tasselled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study
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