3,975 research outputs found

    Adaptive spectral identification techniques in presence of undetected non linearities

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    The standard procedure for detection of gravitational wave coalescing binaries signals is based on Wiener filtering with an appropriate bank of template filters. This is the optimal procedure in the hypothesis of addictive Gaussian and stationary noise. We study the possibility of improving the detection efficiency with a class of adaptive spectral identification techniques, analyzing their effect in presence of non stationarities and undetected non linearities in the noiseComment: 4 pages, 2 figures, uses ws-procs9x6.cls Proceedings of "Non linear physics: theory and experiment. II", Gallipoli (Lecce), 200

    Improved Actions for QCD Thermodynamics on the Lattice

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    Finite cut-off effects strongly influence the thermodynamics of lattice regularized QCD at high temperature in the standard Wilson formulation. We analyze the reduction of finite cut-off effects in formulations of the thermodynamics of SU(N)SU(N) gauge theories with three different O(a2)O(a^2) and O(a4)O(a^4) improved actions. We calculate the energy density and pressure on finite lattices in leading order weak coupling perturbation theory (TT\rightarrow \infty) and perform Monte Carlo simulations with improved SU(3)SU(3) actions at non-zero g2g^2. Already on lattices with temporal extent Nτ=4N_\tau=4 we find a strong reduction of finite cut-off effects in the high temperature limit, which persists also down to temperatures a few times the deconfinement transition temperature.Comment: 20 pages, 3 Postscript figure

    LIGO End-to-End simulation Program

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    A time-domain simulation program has been developed to provide an accurate description of interferometric gravitational wave detectors. This is being utilized to build a model of LIGO with the aim of aiding in the shakedown and integration of the interferometer subsystems, and ultimately the optimization of detector sensitivity

    Structural validation of a realistic wing structure: the RIBES test article

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    Several experimental test cases are available in literature to study and validate fluid structure interaction methods. They, however, focus the attention mainly on replicating typical cruising aerodynamic conditions forcing the adoption of fully steel made models able to operate with the high loads generated in high speed facilities. This translates in a complete loss of similitude with typical realistic aeronautical wing structures configurations. To reverse this trend, and to better study the aerolastic mechanism from a structural point of view, an aeroelastic measurement campaign was carried within the EU RIBES project. A half wing model for wind tunnel tests was designed and manufactured replicating a typical metallic wing box structure, producing a database of loads, pressure, stress and deformation measurements. In this paper the design, manufacturing and validation activities performed within the RIBES project are described, with a focus on the structural behavior of the test article. All experimental data and numerical models are made freely available to the scientific community

    Two-photon excitation selective plane illumination microscopy (2PE-SPIM) of highly scattering samples: Characterization and application

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    In this work we report the advantages provided by two photon excitation (2PE) implemented in a selective plane illumination microscopy (SPIM) when imaging thick scattering samples. In particular, a detailed analysis of the effects induced on the real light sheet excitation intensity distribution is performed. The comparison between single-photon and twophoton excitation profiles shows the reduction of the scattering effects and sample-induced aberrations provided by 2PE-SPIM. Furthermore, uniformity of the excitation distribution and the consequent improved image contrast is shown when imaging scattering phantom samples in depth by 2PE-SPIM. These results show the advantages of 2PE-SPIM and suggest how this combination can further enhance the SPIM performance. Phantom samples have been designed with optical properties compatible with biological applications of interest. © 2013 Optical Society of America

    From risk-based health surveillance to health promotion: an evidence-based experience in a health care setting.

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    Health surveillance’s aim consists in different aspects: (i) to ensure worker’s health, (ii) to comply regulation, (iii) to detect health changes at their onset, (iv) to reduce cost, (v) to provide a fitness for job judgement, (vi) to provide a medical baseline and (vii) to be part of a preventive programme. Some of these aspects are perceived as benefits from the different stakeholders. Employers indicated as benefits worker’s satisfaction improvement, cost reduction, relationship improvement, early detection of health changes5. The study showed some other benefits: an improvement in worker’s satisfaction, an improvement in the relationship between stakeholders (even though based on qualitative data only), an early detection of health changes in few cases and a sickness absence reduction after influenza vaccination programme

    Improving the sensitivity of future GW observatories in the 1-10 Hz band: Newtonian and seismic noise

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    The next generation gravitational wave interferometric detectors will likely be underground detectors to extend the GW detection frequency band to frequencies below the Newtonian noise limit. Newtonian noise originates from the continuous motion of the Earth’s crust driven by human activity, tidal stresses and seismic motion, and from mass density fluctuations in the atmosphere. It is calculated that on Earth’s surface, on a typical day, it will exceed the expected GW signals at frequencies below 10 Hz. The noise will decrease underground by an unknown amount. It is important to investigate and to quantify this expected reduction and its effect on the sensitivity of future detectors, to plan for further improvement strategies. We report about some of these aspects. Analytical models can be used in the simplest scenarios to get a better qualitative and semi-quantitative understanding. As more complete modeling can be done numerically, we will discuss also some results obtained with a finite-element-based modeling tool. The method is verified by comparing its results with the results of analytic calculations for surface detectors. A key point about noise models is their initial parameters and conditions, which require detailed information about seismic motion in a real scenario. We will describe an effort to characterize the seismic activity at the Homestake mine which is currently in progress. This activity is specifically aimed to provide informations and to explore the site as a possible candidate for an underground observatory. Although the only compelling reason to put the interferometer underground is to reduce the Newtonian noise, we expect that the more stable underground environment will have a more general positive impact on the sensitivity.We will end this report with some considerations about seismic and suspension noise

    Double Penguins and the Contribution of Vector Meson--like States to the Decays BKγ,BργB \to K^* \gamma, \, B \to \rho \gamma

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    Using perturbative QCD, the contribution at the leading twist, leading αs\alpha_s level, of charm and up quark loops to the decays BKγB \rightarrow K^* \gamma and BργB \rightarrow \rho \gamma is presented. In the case of BργB \rightarrow \rho \gamma, the relative importance of these contributions depend upon the unknown CKM matrix elements VbuV_{bu} and VtdV_{td}. Assuming that the ratio r=VbcVcd/VbtVtdr = V_{bc}V^*_{cd}/V_{bt}V^*_{td} is bounded between 2.25r.5-2.25 \le r \le -.5 as is suggested by the Particle Data Group, the error in extracting Vtd/Vts |V_{td}/V_{ts}| by these decays is estimated.Comment: 4 double column pages, revtex, 3 figures attached, 2 figures added indicating less optimism concerning the accuracy at which Vtd/Vts|V_{td}/V_{ts}| can be extracted: to appear in PR
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