22,906 research outputs found

    Weakly bound states of polar molecules in bilayers

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    We investigate a system of two polarized molecules in a layered trap. The molecules reside in adjacent layers and interact purely via the dipole-dipole interaction. We determine the properties of the ground state of the system as a function of the dipole moment and polarization angle. A bound state is always present in the system and in the weak binding limit the bound state extends to a very large distance and shows universal behavior.Comment: Presented at the 21st European Conference on Few-Body Problems in Physics, Salamanca, Spain, 30 August - 3 September 201

    Capture of lipopolysaccharide (endotoxin) by the blood clot: A comparative study

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    In vertebrates and arthropods, blood clotting involves the establishment of a plug of aggregated thrombocytes (the cellular clot) and an extracellular fibrillar clot formed by the polymerization of the structural protein of the clot, which is fibrin in mammals, plasma lipoprotein in crustaceans, and coagulin in the horseshoe crab, Limulus polyphemus. Both elements of the clot function to staunch bleeding. Additionally, the extracellular clot functions as an agent of the innate immune system by providing a passive anti-microbial barrier and microbial entrapment device, which functions directly at the site of wounds to the integument. Here we show that, in addition to these passive functions in immunity, the plasma lipoprotein clot of lobster, the coagulin clot of Limulus, and both the platelet thrombus and the fibrin clot of mammals (human, mouse) operate to capture lipopolysaccharide (LPS, endotoxin). The lipid A core of LPS is the principal agent of gram-negative septicemia, which is responsible for more than 100,000 human deaths annually in the United States and is similarly toxic to arthropods. Quantification using theLimulus Amebocyte Lysate (LAL) test shows that clots capture significant quantities of LPS and fluorescent-labeled LPS can be seen by microscopy to decorate the clot fibrils. Thrombi generated in the living mouse accumulate LPS in vivo. It is suggested that capture of LPS released from gram-negative bacteria entrapped by the blood clot operates to protect against the disease that might be caused by its systemic dispersal

    Statistical Analysis Plan: Low Traffic Neighbourhoods in London: Interrupted time series analysis of sensor count data

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    This document is a statistical analysis plan for the NIHR-funded study into Low Traffic Neighbourhoods in London. It outlines the methodological approach (including data cleaning, anomaly detection, imputation and statistical analysis) associated with automated sensor data collected as part of the project. It gives particular detail to the interrupted time series method that, dependent on data availability and suitability, should form a significant part of the analysis of sensor data

    The Dwarf Nova PQ Andromedae

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    We report a photometric study of the WZ Sagittae-type dwarf nova PQ Andromedae. The light curve shows strong (0.05 mag full amplitude) signals with periods of 1263(1) and 634(1) s, and a likely double-humped signal with P=80.6(2) min. We interpret the first two as nonradial pulsation periods of the underlying white dwarf, and the last as the orbital period of the underlying binary. We estimate a distance of 150(50) pc from proper motions and the two standard candles available: the white dwarf and the dwarf-nova outburst. At this distance, the K magnitude implies that the secondary is probably fainter than any star on the main sequence -- indicating a mass below the Kumar limit at 0.075 M_sol. PQ And may be another "period bouncer", where evolution now drives the binary out to longer period.Comment: PDF, 13 pages, 2 figures; accepted, in press, to appear September 2005, PASP; more info at http://cba.phys.columbia.edu

    The importance of financial market development on the relationship between loan guarantees for SMEs and local market employment rates

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    We empirically examine whether a major government intervention in the small-firm credit market yields significantly better results in markets that are less financially developed. The government intervention that we investigate is SBA-guaranteed lending. The literature on financing small and medium size enterprises (SMEs) suggests that small firms may be exposed to a particular type of market failure associated with credit rationing. And SMEs in markets that are less financially developed will likely face a greater degree of this market failure. To test our hypothesis, we use the level of bank deposits per capita as our relative measure of financial market development, and we use local market employment rates as our measure of economic performance. After controlling for the appropriate cross-sectional market characteristics, we find that SBA-guaranteed lending has a significantly more (less) positive impact on the average annual level of employment when the local market is relatively less (more) financially developed. This result has important implications for public policy directives concerning where SBA-guaranteed lending should be directed.Small Business Administration ; Financial markets ; Small business - Finance ; Employment

    Search for muonic decays of the antiproton at the Fermilab Antiproton Accumulator

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    A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on six antiproton decay modes which contain a final-state muon. At the 90% C.L. we find that tau/B(mu gamma) > 5.0 x 10^4 yr, tau/B(mu pi0) > 4.8 x 10^4 yr, tau/B(mu eta) > 7.9 x 10^3 yr, tau/B(mu gamma gamma) > 2.3 x 10^4 yr, tau/B(mu K0S > 4.3 x 10^3 yr, and tau/B(mu K0L) > 6.5 x 10^3 yr.Comment: 8 pages + 3 Postscript figure

    Scheduling language and algorithm development study. Volume 3, phase 2: As-built specifications for the prototype language and module library

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    Detailed specifications of the prototype language and module library are presented. The user guide to the translator writing system is included
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