8,011 research outputs found

    Detection of Illegal Race Walking: A Tool to Assist Coaching and Judging

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    Current judging of race walking in international competitions relies on subjective human observation to detect illegal gait, which naturally has inherent problems. Incorrect judging decisions may devastate an athlete and possibly discredit the international governing body. The aim of this study was to determine whether an inertial sensor could improve accuracy, monitor every step the athlete makes in training and/or competition. Seven nationally competitive race walkers performed a series of legal, illegal and self-selected pace races. During testing, athletes wore a single inertial sensor (100 Hz) placed at S1 of the vertebra and were simultaneously filmed using a high-speed camera (125 Hz). Of the 80 steps analyzed the high-speed camera identified 57 as illegal, the inertial sensor misidentified four of these measures (all four missed illegal steps had 0.008 s of loss of ground contact) which is considerably less than the best possible human observation of 0.06 s. Inertial sensor comparison to the camera found the typical error of estimate was 0.02 s (95% confidence limits 0.01–0.02), with a bias of 0.02 (±0.01). An inertial sensor can thus objectively improve the accuracy in detecting illegal steps (loss of ground contact) and, along with the ability to monitor every step of the athlete, could be a valuable tool to assist judges during race walk events

    Evaluating the cytotoxicity of innate immune effector cells using the GrB ELISPOT assay

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    BACKGROUND: This study assessed the Granzyme B (GrB) ELISPOT as a viable alternative to the (51)Cr-release assay for measuring cytotoxic activity of innate immune effector cells. We strategically selected the GrB ELISPOT assay because GrB is a hallmark effector molecule of cell-mediated destruction of target cells. METHODS: We optimized the GrB ELISPOT assay using the human-derived TALL-104 cytotoxic cell line as effectors against K562 target cells. Titration studies were performed to assess whether the ELISPOT assay could accurately enumerate the number of GrB-secreting effector cells. TALL-104 were treated with various secretion inhibitors and utilized in the GrB ELISPOT to determine if GrB measured in the ELISPOT was due to degranulation of effector cells. Additionally, CD107a expression on effector cells after effector-target interaction was utilized to further confirm the mechanism of GrB release by TALL-104 and lymphokine-activated killer (LAK) cells. Direct comparisons between the GrB ELISPOT, the IFN-γ ELISPOT and the standard (51)Cr-release assays were made using human LAK cells. RESULTS: Titration studies demonstrated a strong correlation between the number of TALL-104 and LAK effector cells and the number of GrB spots per well. GrB secretion was detectable within 10 min of effector-target contact with optimal secretion observed at 3–4 h; in contrast, optimal IFN-γ secretion was not observed until 24 h. The protein secretion inhibitor, brefeldin A, did not inhibit the release of GrB but did abrogate IFN-γ production by TALL-104 cells. GrB secretion was abrogated by BAPTA-AM (1,2-bis-(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid tetra(acetoxymethyl) ester), which sequesters intracellular Ca(2+), thereby preventing degranulation. The number of effector cells expressing the degranulation associated glycoprotein CD107a increased after interaction with target cells and correlated with the stimulated release of GrB measured in the ELISPOT assay. CONCLUSIONS: Because of its high sensitivity and ability to estimate cytotoxic effector cell frequency, the GrB ELISPOT assay is a viable alternative to the (51)Cr-release assay to measure MHC non-restricted cytotoxic activity of innate immune cells. Compared to the IFN-γ ELISPOT assay, the GrB ELISPOT may be a more direct measure of cytotoxic cell activity. Because GrB is one of the primary effector molecules in natural killer (NK) cell-mediated killing, detection and enumeration of GrB secreting effector cells can provide valuable insight with regards to innate immunological responses

    Theory of Cylindrical Tubules and Helical Ribbons of Chiral Lipid Membranes

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    We present a general theory for the equilibrium structure of cylindrical tubules and helical ribbons of chiral lipid membranes. This theory is based on a continuum elastic free energy that permits variations in the direction of molecular tilt and in the curvature of the membrane. The theory shows that the formation of tubules and helical ribbons is driven by the chirality of the membrane. Tubules have a first-order transition from a uniform state to a helically modulated state, with periodic stripes in the tilt direction and ripples in the curvature. Helical ribbons can be stable structures, or they can be unstable intermediate states in the formation of tubules.Comment: 43 pages, including 12 postscript figures, uses REVTeX 3.0 and epsf.st

    Plan for Subdividing Genesis Mission Diamond-on-Silicon 60000 Solar Wind Collector

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    NASA's Genesis solar wind sample return mission experienced an off nominal landing resulting in broken, albeit useful collectors. Sample 60000 from the collector is comprised of diamond-like-carbon film on a float zone (FZ) silicon wafer substrate Diamond-on-Silicon (DOS), and is highly prized for its higher concentration of solar wind (SW) atoms. A team of scientist at the Johnson Space Center was charged with determining the best, nondestructive and noncontaminating method to subdivide the specimen that would result in a 1 sq. cm subsample for allocation and analysis. Previous work included imaging of the SW side of 60000, identifying the crystallographic orientation of adjacent fragments, and devising an initial cutting plan

    Towards a synthesized critique of neoliberal biodiversity conservation

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    During the last three decades, the arena of biodiversity conservation has largely aligned itself with the globally dominant political ideology of neoliberalism and associated governmentalities. Schemes such as payments for ecological services are promoted to reach the multiple ‘wins’ so desired: improved biodiversity conservation, economic development, (international) cooperation and poverty alleviation, amongst others. While critical scholarship with respect to understanding the linkages between neoliberalism, capitalism and the environment has a long tradition, a synthesized critique of neoliberal conservation - the ideology (and related practices) that the salvation of nature requires capitalist expansion - remains lacking. This paper aims to provide such a critique. We commence with the assertion that there has been a conflation between ‘economics’ and neoliberal ideology in conservation thinking and implementation. As a result, we argue, it becomes easier to distinguish the main problems that neoliberal win-win models pose for biodiversity conservation. These are framed around three points: the stimulation of contradictions; appropriation and misrepresentation and the disciplining of dissent. Inspired by Bruno Latour’s recent ‘compositionist manifesto’, the conclusion outlines some ideas for moving beyond critique
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