10,320 research outputs found

    Automated documentation generator for advanced protein crystal growth

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    The System Management and Production Laboratory at the Research Institute, the University of Alabama in Huntsville (UAH), was tasked by the Microgravity Experiment Projects (MEP) Office of the Payload Projects Office (PPO) at Marshall Space Flight Center (MSFC) to conduct research in the current methods of written documentation control and retrieval. The goals of this research were to determine the logical interrelationships within selected NASA documentation, and to expand on a previously developed prototype system to deliver a distributable, electronic knowledge-based system. This computer application would then be used to provide a paperless interface between the appropriate parties for the required NASA document

    Activation of myocardial cAMP-dependent protein kinase by lysoplasmenylcholine

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    AbstractPlasmalogen-specific, calcium-independent phospholipase A2 (iPLA2) is activated during myocardial ischemia. Accordingly, we have assessed the activation of myocardial protein kinases by the iPLA2 product, lysoplasmenylcholine. Lysoplasmenylcholine-activated protein kinase activity from heart cytosol fractionated on a DE-52 column was identified as cAMP-dependent protein kinase (PKA) based on the following: (1) protein kinase activity stimulated by cAMP and lysoplasmenylcholine co-eluted on sequential chromatographic steps; (2) lysoplasmenylcholine-activated protein kinase activity was inhibited by the PKA inhibitor, PKI; and (3) the unprimed PKA form generated from the primed form of PKA was activated by cAMP and lysoplasmenylcholine. These results demonstrate a novel mechanism for PKA activation by lysoplasmenylcholine

    A Search for Planets Transiting the M Dwarf Debris Disk Host, AU Microscopii

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    We present high cadence, high precision multi-band photometry of the young, M1Ve, debris disk star, AU Microscopii. The data were obtained in three continuum filters spanning a wavelength range from 4500\AA to 6600\AA, plus Hα\alpha, over 28 nights in 2005. The lightcurves show intrinsic stellar variability due to starspots with an amplitude in the blue band of 0.051 magnitudes and a period of 4.847 days. In addition, three large flares were detected in the data which all occur near the minimum brightness of the star. We remove the intrinsic stellar variability and combine the lightcurves of all the filters in order to search for transits by possible planetary companions orbiting in the plane of the nearly edge-on debris disk. The combined final lightcurve has a sampling of 0.35 minutes and a standard deviation of 6.8 millimags (mmag). We performed Monte Carlo simulations by adding fake transits to the observed lightcurve and find with 95% significance that there are no Jupiter mass planets orbiting in the plane of the debris disk on circular orbits with periods, P ≤5\le 5 days. In addition, there are no young Neptune-like planets (with radii 2.5×\times smaller than the young Jupiter) on circular orbits with periods, P ≤3\le 3 days.Comment: accepted to MNRA

    Plasmalogen and anionic phospholipid dependence of the cardiac sarcolemmal sodium-calcium exchanger

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    AbstractAlthough plasmalogens are the predominant phospholipids of cardiac sarcolemma, their physiological role has not been forthcoming. Since the cardiac sarcolemmal sodium-calcium exchanger has been proposed to be regulated by anionic phospholipids, the roles of plasmalogens and anionic phospholipids as regulators of the sodium-calcium exchanger were explored. Reconstituted sodium-calcium exchange activity in plasmalogen-containing proteoliposomes was 10-fold higher than that in control proteoliposomes comprised of only diacyl phospholipids. Additionally, exchange activity in plasmalogen-containing proteoliposomes was regulated by anionic phospholipids. Thus, plasmalogens provide a critical lipid environment in which anionic phospholipids serve as boundary lipids for the regulation of the trans-sarcolemmal sodium-calcium exchanger

    Bayesian Methods for Analysis and Adaptive Scheduling of Exoplanet Observations

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    We describe work in progress by a collaboration of astronomers and statisticians developing a suite of Bayesian data analysis tools for extrasolar planet (exoplanet) detection, planetary orbit estimation, and adaptive scheduling of observations. Our work addresses analysis of stellar reflex motion data, where a planet is detected by observing the "wobble" of its host star as it responds to the gravitational tug of the orbiting planet. Newtonian mechanics specifies an analytical model for the resulting time series, but it is strongly nonlinear, yielding complex, multimodal likelihood functions; it is even more complex when multiple planets are present. The parameter spaces range in size from few-dimensional to dozens of dimensions, depending on the number of planets in the system, and the type of motion measured (line-of-sight velocity, or position on the sky). Since orbits are periodic, Bayesian generalizations of periodogram methods facilitate the analysis. This relies on the model being linearly separable, enabling partial analytical marginalization, reducing the dimension of the parameter space. Subsequent analysis uses adaptive Markov chain Monte Carlo methods and adaptive importance sampling to perform the integrals required for both inference (planet detection and orbit measurement), and information-maximizing sequential design (for adaptive scheduling of observations). We present an overview of our current techniques and highlight directions being explored by ongoing research.Comment: 29 pages, 11 figures. An abridged version is accepted for publication in Statistical Methodology for a special issue on astrostatistics, with selected (refereed) papers presented at the Astronomical Data Analysis Conference (ADA VI) held in Monastir, Tunisia, in May 2010. Update corrects equation (3
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