15,791 research outputs found

    Cosmic Neutrino Bound on the Dark Matter Annihilation Rate in the Late Universe

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    How large can the dark matter self-annihilation rate in the late universe be? This rate depends on (rho_DM/m_chi)^2 , where rho_DM/m_chi is the number density of dark matter, and the annihilation cross section is averaged over the velocity distribution. Since the clustering of dark matter is known, this amounts to asking how large the annihilation cross section can be. Kaplinghat, Knox, and Turner proposed that a very large annihilation cross section could turn a halo cusp into a core, improving agreement between simulations and observations; Hui showed that unitarity prohibits this for large dark matter masses. We show that if the annihilation products are Standard Model particles, even just neutrinos, the consequent fluxes are ruled out by orders of magnitude, even at small masses. Equivalently, to invoke such large annihilation cross sections, one must now require that essentially no Standard Model particles are produced.Comment: 4 pages, 2 figures; to appear in the proceedings of the TeV Particle Astrophysics II Workshop, Madison, Wisconsin, 28-31 Aug 200

    Gamma-ray bursts during neutron star formation. Gamma-ray bursts and transient X-ray sources

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    Discussions are presented of the associations between cosmic gamma ray bursts and transient X-ray sources, and the release of gravitational binding energy during the formation of neutron stars. The model for studying the associations is described along with the release of neutrinos during the collapse of white dwarfs

    CosmoDM and its application to Pan-STARRS data

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    The Cosmology Data Management system (CosmoDM) is an automated and flexible data management system for the processing and calibration of data from optical photometric surveys. It is designed to run on supercomputers and to minimize disk I/O to enable scaling to very high throughput during periods of reprocessing. It serves as an early prototype for one element of the ground-based processing required by the Euclid mission and will also be employed in the preparation of ground based data needed in the eROSITA X-ray all sky survey mission. CosmoDM consists of two main pipelines. The first is the single-epoch or detrending pipeline, which is used to carry out the photometric and astrometric calibration of raw exposures. The second is the co- addition pipeline, which combines the data from individual exposures into deeper coadd images and science ready catalogs. A novel feature of CosmoDM is that it uses a modified stack of As- tromatic software which can read and write tile compressed images. Since 2011, CosmoDM has been used to process data from the DECam, the CFHT MegaCam and the Pan-STARRS cameras. In this paper we shall describe how processed Pan-STARRS data from CosmoDM has been used to optically confirm and measure photometric redshifts of Planck-based Sunyaev-Zeldovich effect selected cluster candidates.Comment: 11 pages, 4 figures. Proceedings of Precision Astronomy with Fully Depleted CCDs Workshop (2014). Accepted for publication in JINS

    Enhancement of thermal conductivity of materials using different forms of natural graphite.

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    The quest for improvement of thermal conductivity in every area including aerospace structures is gaining momentum as the modern day technology is embedded with electronics which generate considerable amounts of heat energy. In some other applications, the thermal energy must be absorbed or released at a very fast rate. Natural graphite is highly anisotropic and has excellent thermal and electrical conductivity in a-direction hence; it is one of the potential candidates to enhance thermal conductivity. This paper encompasses various preparation routes used to enhance thermal conductivity in materials/composites using graphite flakes in its natural and treated forms along with characterization results of thermal conductivity and/ or electrical resistivity where available. Addition of graphite has shown to improve thermal conductivity in some materials by 30-130 times whereas one method of preparation described here shows composites to have thermal conductivity as high as 750 W/m K

    Attitudes to self-sampling for HPV among Indian, Pakistani, African-Caribbean and white British women in Manchester, UK

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    Objective: To examine attitudes to self-sampling for human papillomavirus (HPV) testing among women from contrasting ethnic groups.Setting: Manchester, UK.Methods: Two hundred women of Indian, Pakistani, African-Caribbean and white British origin were recruited from social and community groups to participate in a questionnaire survey. The questionnaire included items on attitudes to self-sampling and intention to use the test.Results: Willingness to try to use the test was high, and women did not foresee religious or cultural barriers to self-sampling; however, a large proportion of women were concerned about doing the test properly. This concern was greatest in the Indian and African-Caribbean groups.Conclusions: Although women's willingness to try self-sampling for HPV is encouraging, worries about carrying out the procedure correctly must be addressed if women are to feel confident about the results of self-sampling methods and reassured by a negative result

    Reliable dual-redundant sensor failure detection and identification for the NASA F-8 DFBW aircraft

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    A technique was developed which provides reliable failure detection and identification (FDI) for a dual redundant subset of the flight control sensors onboard the NASA F-8 digital fly by wire (DFBW) aircraft. The technique was successfully applied to simulated sensor failures on the real time F-8 digital simulator and to sensor failures injected on telemetry data from a test flight of the F-8 DFBW aircraft. For failure identification the technique utilized the analytic redundancy which exists as functional and kinematic relationships among the various quantities being measured by the different control sensor types. The technique can be used not only in a dual redundant sensor system, but also in a more highly redundant system after FDI by conventional voting techniques reduced to two the number of unfailed sensors of a particular type. In addition the technique can be easily extended to the case in which only one sensor of a particular type is available

    Stellar Mass to Halo Mass Scaling Relation for X-ray Selected Low Mass Galaxy Clusters and Groups out to Redshift z1z\approx1

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    We present the stellar mass-halo mass scaling relation for 46 X-ray selected low-mass clusters or groups detected in the XMM-BCS survey with masses 2×1013MM5002.5×1014M2\times10^{13}M_{\odot}\lesssim M_{500}\lesssim2.5\times10^{14}M_{\odot} at redshift 0.1z1.020.1\le z \le1.02. The cluster binding masses M500M_{500} are inferred from the measured X-ray luminosities \Lx, while the stellar masses MM_{\star} of the galaxy populations are estimated using near-infrared imaging from the SSDF survey and optical imaging from the BCS survey. With the measured \Lx\ and stellar mass MM_{\star}, we determine the best fit stellar mass-halo mass relation, accounting for selection effects, measurement uncertainties and the intrinsic scatter in the scaling relation. The resulting mass trend is MM5000.69±0.15M_{\star}\propto M_{500}^{0.69\pm0.15}, the intrinsic (log-normal) scatter is σlnMM500=0.360.06+0.07\sigma_{\ln M_{\star}|M_{500}}=0.36^{+0.07}_{-0.06}, and there is no significant redshift trend M(1+z)0.04±0.47M_{\star}\propto (1+z)^{-0.04\pm0.47}, although the uncertainties are still large. We also examine MM_{\star} within a fixed projected radius of 0.50.5~Mpc, showing that it provides a cluster binding mass proxy with intrinsic scatter of 93%\approx93\% (1σ\sigma in M500M_{500}). We compare our M=M(M500,z)M_{\star}=M_{\star}(M_{500}, z) scaling relation from the XMM-BCS clusters with samples of massive, SZE-selected clusters (M5006×1014MM_{500}\approx6\times10^{14}M_{\odot}) and low mass NIR-selected clusters (M5001014MM_{500}\approx10^{14}M_{\odot}) at redshift 0.6z1.30.6\lesssim z \lesssim1.3. After correcting for the known mass measurement systematics in the compared samples, we find that the scaling relation is in good agreement with the high redshift samples, suggesting that for both groups and clusters the stellar content of the galaxy populations within R500R_{500} depends strongly on mass but only weakly on redshift out to z1z\approx1.Comment: 15 pages, 10 figures. Accepted for publication in MNRA

    Development of an information sheet providing rapport advice for interpreters in police interviews

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    The present paper reports the development of an information sheet designed to aid interpreters in police interviews in recognizing, conveying and inadvertently obstructing rapport-building efforts by police interviewers. The contents of this sheet were informed by past research defining rapport, and rapport uses in police interviews. We used a mixed experimental design to test the information sheet. One group (Intervention, n = 35) was randomly assigned to read an information sheet before responding to short vignettes of police interviewing foreign non-English speaking suspects about international crimes, while another (Control) group (n = 37) simply responded to the vignettes. Perceptions of rapport cues by the intervention group exceeded that of the control group. However, the groups performed equally well at identifying appropriate methods to convey/avoid obstructing rapport. Feedback from the intervention group on the helpfulness of the information sheet was largely positive. The findings were used to improve the information sheet which can be used to alert interpreters to the importance of rapport in suspect interviews

    Kinesin Light Chains Are Essential for Axonal Transport in Drosophila

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    Kinesin is a heterotetramer composed of two 115-kD heavy chains and two 58-kD light chains. The microtubule motor activity of kinesin is performed by the heavy chains, but the functions of the light chains are poorly understood. Mutations were generated in the Drosophila gene Kinesin light chain (Klc), and the phenotypic consequences of loss of Klc function were analyzed at the behavioral and cellular levels. Loss of Klc function results in progressive lethargy, crawling defects, and paralysis followed by death at the end of the second larval instar. Klc mutant axons contain large aggregates of membranous organelles in segmental nerve axons. These aggregates, or organelle jams (Hurd, D.D., and W.M. Saxton. 1996. Genetics. 144: 1075-1085), contain synaptic vesicle precursors as well as organelles that may be transported by kinesin, kinesin-like protein 68D, and cytoplasmic dynein, thus providing evidence that the loss of Klc function blocks multiple pathways of axonal transport. The similarity of the Klc and Khc ((Saxton et al. Cell 64:1093-1102; Hurd, D.D., and W.M. Saxton. 1996. Genetics 144: 1075-1085) mutant phenotypes indicates that KLC is essential for kinesin function, perhaps by tethering KHC to intracellular cargos or by activating the kinesin motor

    An Information Based Routing Model for Hazardous Material Route Selection Problem

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    oai:iser.sisengr.org:article/2In this paper, we address some key research questions concerning the alternative routing policy of hazardous materials in real time using stochastic dynamic networks based on real life situations. The scenario that we address in this paper involves the use of sophisticated communication tools to provide information on the current condition of the optimal path and incorporate them in our optimization model to generate alternative routes for hazmat vehicles. We address the issues of designing a framework and requirements for an adaptive routing system. To overcome system instability and information overloading, a feeback based routing policy within the framework has been developed. We show the implementation of the framework and disucss the potential benefits of our approach with the help of numerical experiments based on a real hazmat transportation network
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