10,118 research outputs found

    Towards a Realistic MSSM Prediction for Neutrino-nucleon Deep-inelastic Scattering

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    We discuss the radiative corrections to charged and neutral current deep-inelastic neutrino--nucleon scattering in the minimal supersymmetric standard model (MSSM). In particular, we study deviations, delta_R^nu(nu-bar), from the Standard Model prediction for the ratios of neutral- to charged-current cross sections, taking into account all sources for deviations in the MSSM, i.e. different contributions from virtual Higgs bosons and virtual superpartners. Our calculation includes the full q^2 dependence of the one-loop amplitudes, parton distribution functions and a NuTeV-inspired process kinematics. We present results of a scan of delta_R^nu(nu-bar) over the relevant MSSM parameter space.Comment: 5 pages, 2 figures, to appear in Proceedings of SUSY06, the 14th International Conference on Supersymmetry and the Unification of Fundamental Interactions, UC Irvine, California, 12-17 June 200

    Sparse Control of Alignment Models in High Dimension

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    For high dimensional particle systems, governed by smooth nonlinearities depending on mutual distances between particles, one can construct low-dimensional representations of the dynamical system, which allow the learning of nearly optimal control strategies in high dimension with overwhelming confidence. In this paper we present an instance of this general statement tailored to the sparse control of models of consensus emergence in high dimension, projected to lower dimensions by means of random linear maps. We show that one can steer, nearly optimally and with high probability, a high-dimensional alignment model to consensus by acting at each switching time on one agent of the system only, with a control rule chosen essentially exclusively according to information gathered from a randomly drawn low-dimensional representation of the control system.Comment: 39 page

    Experimental and numerical studies of terahertz surface waves on a thin metamaterial film

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    We present experimental and numerical studies of localized terahertz surface waves on a subwavelength-thick metamaterial film consisting of in-plane split-ring resonators. A simple and intuitive model is derived that describes the propagation of surface waves as guided modes in a waveguide filled with a Lorentz-like medium. The effective medium model allows to deduce the dispersion relation of the surface waves in excellent agreement with the numerical data obtained from 3-D full-wave calculations. Both the accuracy of the analytical model and the numerical calculations are confirmed by spectroscopic terahertz time domain measurements.Comment: 3 pages, 3 figure

    Airborne lidar observations supporting the ADM-Aeolus mission for global wind profiling

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    The Atmospheric Dynamics Mission ADM-Aeolus of ESA will be the first lidar mission to sense the global wind field from space. The instrument is based on a direct-detection Doppler lidar operating at 354.9 nm with two spectrometers for aerosol/cloud and molecular backscatter. In order to assess the performance of the Doppler lidar ALADIN on ADM-Aeolus and to optimize the retrieval algorithms with atmospheric signals, an airborne prototype – the ALADIN Airborne Demonstrator A2D – was developed. The A2D was the first airborne direct-detection Doppler lidar with its maiden flight on the DLR Falcon aircraft in 2005. Three airborne campaigns with a coherent-detection 2-μm wind lidar and the direct-detection wind lidar A2D were performed for pre-launch validation of Aeolus from 2007-2009. Furthermore, a unique experiment for resolving the Rayleigh-Brillouin spectral line shape in the atmosphere was accomplished in 2009 with the A2D from a mountain observatory at an altitude of 2650 m. Results of this experiment and the latest airborne campaign in the vicinity of Greenland and Iceland will be discussed

    Gradient Index Metamaterial Based on Slot Elements

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    We present a gradient-index (GRIN) metamaterial based on an array of annular slots. The structure allows a large variation of the effective refractive index under normal-to-plane incidence and thus enables the construction of GRIN devices consisting of only a small number of functional layers. Using full-wave simulations, we demonstrate the annular slot concept by means of a 3-unit-cell thin GRIN lens for the terahertz (THz) range. In the presented realizations, we achieved an index contrast of Delta n = 1.5 resulting in a highly refractive lens suitable for focusing THz radiation to a spot size smaller than the wavelength.Comment: 4 pages, 5 figure

    Evaluating the impact of outdoor orientation on incoming students\u27 perceptions of social norms about alcohol use on campus

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    Alcohol issues are a concern of colleges and universities (National Institutes of Health, 2008). This study assessed the effects of an outdoor orientation program on the alcohol use and perceptions of program participants. Specifically, 30 outdoor orientation leaders participated in a three-hour training based on the social norms approach (Berkowitz, 2005). A repeated-measures, quasi-experimental design was used to collect data on incoming students\u27 own use and approval of alcohol, and their perceptions of other students\u27 use and approval. Results indicated that untrained leaders were carriers of the misperception of permissive alcohol use (Perkins, 1997) negatively effecting incoming students perceptions. Trained leaders did not reduce participants misperceptions, however misperceptions in these groups did not increase. These results suggest the need for social norms training for outdoor orientation leaders to minimize their potential for spreading misinformation about alcohol use norms on campus. An outdoor orientation training model is presented
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