24,906 research outputs found

    Distribution of Complex and Core Lipids within New Hyperthermophilic Members of the Archaea Domain

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    Core and complex lipids of several new hyperthermophilic archaeal isolates were analyzed. The organisms belong to the Sulfolobales,Archaeoglobus, Pyrobaculum, and Methanococcus. A detailed structural investigation of complex lipids of Pyrobaculum species is reported. The different lipid structures are of help for a rapid and simple phylogenetic classification of the new isolates. They are in agreement with the classification based on other features

    Experimentally Feasible Security Check for n-qubit Quantum Secret Sharing

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    In this article we present a general security strategy for quantum secret sharing (QSS) protocols based on the HBB scheme presented by Hillery, Bu\v{z}ek and Berthiaume [Phys. Rev A \textbf{59}, 1829 (1999)]. We focus on a generalization of the HBB protocol to nn communication parties thus including nn-partite GHZ states. We show that the multipartite version of the HBB scheme is insecure in certain settings and impractical when going to large nn. To provide security for such QSS schemes in general we use the framework presented by some of the authors [M. Huber, F. Minert, A. Gabriel, B. C. Hiesmayr, Phys. Rev. Lett. \textbf{104}, 210501 (2010)] to detect certain genuine nn partite entanglement between the communication parties. In particular, we present a simple inequality which tests the security.Comment: 5 pages, submitted to Phys. Rev.

    HIV/AIDS, Security and Conflict: New Realities, New Responses

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    Ten years after the HIV/AIDS epidemic itself was identified as a threat to international peace and security, findings from the three-year AIDS, Security and Conflict Initiative (ASCI)(1) present evidence of the mutually reinforcing dynamics linking HIV/AIDS, conflict and security

    Transition from van-der-Waals to H Bonds dominated Interaction in n-Propanol physisorbed on Graphite

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    Multilayer sorption isotherms of 1-propanol on graphite have been measured by means of high-resolution ellipsometry within the liquid regime of the adsorbed film for temperatures ranging from 180 to 260 K. In the first three monolayers the molecules are oriented parallel to the substrate and the growth is roughly consistent with the Frenkel-Halsey-Hill-model (FHH) that is obeyed in van-der-Waals systems on strong substrates. The condensation of the fourth and higher layers is delayed with respect to the FHH-model. The fourth layer is actually a bilayer. Furthermore there is indication of a wetting transition. The results are interpreted in terms of hydrogen-bridge bonding within and between the layers.Comment: 4 pages, 3 figure

    Flicker as a tool for characterizing planets through Asterodensity Profiling

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    Variability in the time series brightness of a star on a timescale of 8 hours, known as 'flicker', has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. (2013). Although surface gravity is crucial for stellar classification, it is the mean stellar density which is most useful when studying transiting exoplanets, due to its direct impact on the transit light curve shape. Indeed, an accurate and independent measure of the stellar density can be leveraged to infer subtle properties of a transiting system, such as the companion's orbital eccentricity via asterodensity profiling. We here calibrate flicker to the mean stellar density of 439 Kepler targets with asteroseismology, allowing us to derive a new empirical relation given by log10(ρ[kgm3])=5.4131.850log10(F8[ppm])\log_{10}(\rho_{\star}\,[\mathrm{kg}\,\mathrm{m}^{-3}]) = 5.413 - 1.850 \log_{10}(F_8\,[\mathrm{ppm}]). The calibration is valid for stars with 45004500K<Teff<6500<T_{\mathrm{eff}}<6500K, KP<14K_P<14 and flicker estimates corresponding to stars with 3.25<logg<4.433.25<\log g_{\star}<4.43. Our relation has a model error in the stellar density of 31.7% and so has 8\sim8 times lower precision than that from asteroseismology but is applicable to a sample 40\sim40 times greater. Flicker therefore provides an empirical method to enable asterodensity profiling on hundreds of planetary candidates from present and future missions.Comment: 6 pages, 3 figures, 1 table. Accepted to ApJ Letters. Code available at https://www.cfa.harvard.edu/~dkipping/flicker.htm

    Probing Sterile Neutrino Parameters with Double Chooz, Daya Bay and RENO

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    In this work, we present a realistic analysis of the potential of the present-day reactor experiments Double Chooz, Daya Bay and RENO for probing the existence of sterile neutrinos. We present exclusion regions for sterile oscillation parameters for each of these experiments, using simulations with realistic estimates of systematic errors and detector resolutions, and compare the sterile parameter sensitivity regions we obtain with the existing bounds from other reactor experiments. We find that these experimental set-ups give significant bounds on the parameter \Theta_{ee} especially in the low sterile oscillation region 0.01 < \Delta m_{41}^2 < 0.05 eV^2. These bounds can add to our understanding of the sterile neutrino sector since there is still a tension in the allowed regions from different experiments for sterile parameters.Comment: 12 pages, 5 figure
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