2,585 research outputs found

    Free Radicals in Superfluid Liquid Helium Nanodroplets: A Pyrolysis Source for the Production of Propargyl Radical

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    An effusive pyrolysis source is described for generating a continuous beam of radicals under conditions appropriate for the helium droplet pick-up method. Rotationally resolved spectra are reported for the Îœ1\nu_1 vibrational mode of the propargyl radical in helium droplets at 3322.15 cm−1^{-1}. Stark spectra are also recorded that allow for the first experimental determination of the permanent electric dipole moment of propargyl, namely -0.150 D and -0.148 D for ground and excited state, respectively, in good agreement with previously reported ab initio results of -0.14 D [1]. The infrared spectrum of the Îœ1\nu_1 mode of propargyl-bromide is also reported. The future application of these methods for the production of novel radical clusters is discussed

    Magnetized Iron Atmospheres for Neutron Stars

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    Using a Hartree-Fock formalism, we estimate energy levels and photon cross sections for atomic iron in magnetic fields B ~ 10^13 G. Computing ionization equilibrium and normal mode opacities with these data, we construct LTE neutron star model atmospheres at 5.5 < Log(T_eff) < 6.5 and compute emergent spectra. We examine the dependence of the emergent spectra on T_eff and B. We also show the spectral variation with the angle between the magnetic field and the atmosphere normal and describe the significant limb darkening in the X-ray band. These results are compared with recent detailed computations of neutron star H model atmospheres in high fields and with low field Fe and H model atmospheres constructed from detailed opacities. The large spectral differences for different surface compositions may be discernible with present X-ray data; we also note improvements needed to allow comparison of Fe models with high quality spectra.Comment: 18 pages with 5 eps figures, accepted for publication in ApJ Replaced due to clerical error only: one more author, no new conten

    (±)-trans-3-Oxo-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a Ύ-keto acid

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    The title compound, C15H16O3, aggregates as hydrogen-bonded catemers progressing from each carboxyl to the ketone of a screw-related neighbor [O⋯O = 2.6675 (14) Å and O—H⋯O = 170°]. Two parallel centrosymmetrically related single-strand hydrogen-bonding helices proceed through the cell in the b-axis direction. The packing includes three inter­molecular C—H⋯O=C close contacts, involving both the ketone and the carboxyl group. The structure is isomorphous with that of the previously described Δ4 α,ÎČ-unsaturated ketone

    A Comparison of Three Different Warm-Ups on 800-Meter Running Performance in Elite Division I Track Athletes – A Pilot Study

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    International Journal of Exercise Science 14(6): 1400-1407, 2021. Track and Field athletes perform different types of warm-ups at varying levels of volume and/or intensity prior to competition. Theoretically, this prepares sport specific muscles for activity by increasing muscle temperature, thus mitigating the chance for injury. There is a paucity of information regarding the optimum level for warm-ups regarding maximizing performance in middle distance events. The aim of this study was to examine the effects of three different warm-ups on 800-meter performance. Thirteen Division I student-athletes (seven males and six females) from the Southeastern Conference (SEC) who were middle distance runners participated in this study. We utilized a randomized, cross-over study design to test low, medium, and high-volume warm-up protocols on 800-meter performance. Trials were conducted over a span of three weeks on a SEC University outdoor track. We used a 2 (Sex) x 3 (Warm-Up Protocol) mixed-factor ANOVA, and our results show a main effect of warm-up volume that is not moderated by sex. Post-hoc tests reveal a high-volume warm-up yields superior results for the 800-meter run in comparison to a medium volume warm-up, which provides better results than a low-volume warm-up. These findings may be of value in providing information in program design for coaches on the most effective warm-up protocols for 800-meter runners. Identifying the best warm-up protocol to prime an 800-meter runner for peak performance may not only assist in preventing injury, but enhance performance thus leading to an increased of achievement, and confidence in personal ability

    Phase-resolved Crab Studies with a Cryogenic TES Spectrophotometer

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    We are developing time- and energy-resolved near-IR/optical/UV photon detectors based on sharp superconducting-normal transition edges in thin films. We report observations of the Crab pulsar made during prototype testing at the McDonald 2.7m telescope with a fiber-coupled transition-edge sensor (TES) system. These data show substantial (d[alpha]~0.3), rapid variations in the spectral index through the pulse profile, with a strong phase-varying IR break across our energy band. These variations correlate with X-ray spectral variations, but no single synchrotron population can account for the full Spectral Energy Distribution (SED). We also describe test spectrophotopolarimetry observations probing the energy dependence of the polarization sweep; this may provide a new key to understanding the radiating particle population.Comment: 12 pages, 10 figures -- to appear in ApJ V56

    PaleoBank, A Relational Database for Invertebrate Paleontology: The Data Model

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    7 p., 1 fig., 2 tables.http://paleo.ku.edu/contributions.htm

    SAURON Observations of Disks in Early-Type Galaxies

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    We briefly describe the SAURON project, aimed at determining the intrinsic shape and internal dynamics of spheroids. We focus here on the ability of SAURON to identify gaseous and stellar disks and to measure their morphology and kinematics. We illustrate some of our results with complete maps of NGC3377, NGC3623, and NGC4365.Comment: 4 pages, 4 figures (newpasp.sty). To appear in ASP Conf. Series "Galaxy Disks and Disk Galaxies", eds. J.G. Funes S.J. & E.M. Corsini. Version with full resolution images available at http://www.strw.leidenuniv.nl/~bureau/pub_list.htm

    Subsidizing Religious Participation through Groups: A Model of the “Megachurch” Strategy for Growth

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    Either despite or because of their non-traditional approach, megachurches have grown significantly in the United States since 1980. This paper models religious participation as an imperfect public good which, absent intervention, yields suboptimal participation by members from the church’s perspective. Megachurches address this problem in part by employing secular-based group activities to subsidize religious participation that then translates into an increase in the attendees’ religious investment. This strategy not only allows megachurches to attract and retain new members when many traditional churches are losing members but also results in higher levels of an individual’s religious capital. As a result, the megachurch may raise expectations of members’ levels of commitment and faith practices. Data from the FACT2000 survey provide evidence that megachurches employ groups more extensively than other churches, and this approach is consistent with a strategy to use groups to help subsidize individuals’ religious investment. Religious capital rises among members of megachurches relative to members of non-megachurches as a result of this strategy

    Are Miami blues in Cuba? A review of the genus \u3ci\u3eCyclargus\u3c/i\u3e Nabokov (Lepidoptera: Lycaenidae) with implications for conservation management

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    We review the genus Cyclargus Nabokov (Lepidoptera: Lycaenidae) based on detailed comparative analyses of wing patterns, genitalia, and mitochondrial COI DNA barcode sequences, and suggest that Cyclargus is composed of four species: C. thomasi (Clench), C. woodruffi (W. Comstock and Huntington), C. ammon (Lucas), and C. dominica (Möschler). The following new subjective synonyms are proposed: C. erembis Nabokov syn. n. and C. kathleena K. Johnson and Matusik syn. n. are C. thomasi noeli (W. Comstock and Huntington); C. sorpresus K. Johnson and Matusik syn. n. and C. shuturn K. Johnson and BĂĄlint syn. n. are C. ammon; and Cyclargus oualiri Brevignon syn. n. is C. woodruffi. Additionally, we report the discovery of C. thomasi noeli in Cuba (where this taxon was previously confused with C. ammon), report C. ammon from Hispaniola for the first time, and document the widespread sympatry of C. thomasi and C. ammon in the northern Caribbean (including south Florida, Cuba, Cayman Islands, Hispaniola, Lucayan Archipelago). Finally, we provide a provisional synonymic list of Cyclargus taxa, which may serve as a taxonomic framework to assist efforts to conserve the Miami blue (C. thomasi bethunebakeri (W. Comstock and Huntington)), a taxon listed as “Endangered” under the Endangered Species Act in the United States

    Increased Oxygen Recovery from Sabatier Systems Using Plasma Pyrolysis Technology and Metal Hydride Separation

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    State-of-the-art life support carbon dioxide (CO2) reduction technology is based on the Sabatier reaction where less than 50% of the oxygen required for the crew is recovered from metabolic CO2. The reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by the limited availability of reactant hydrogen. This is further exacerbated when Sabatier methane (CH4) is vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover hydrogen has the potential to dramatically increase oxygen recovery and thus drastically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. Due to the highly unstable nature of acetylene, a separation system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of a full-scale Third Generation PPA is reported and investigations into metal hydride hydrogen separation technology is discussed
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