857 research outputs found

    Bulk, rare earth and other trace elements in Apollo 14 and 15 and Luna 16 samples

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    The chemical abundances were measured by instrumental and radiochemical neutron activation analysis in a variety of lunar specimens. Apollo 14 soils are characterized by significant enrichments of Al2O3, Na2O and K2O and depletions of TiO2, FeO, MnO and Cr2O3 relative to Apollo 11 and to most of Apollo 12 soils. The uniform abundances in 14230 core tube soils and three other Apollo 14 soils indicate that the regolith is uniform to at least 22 cm depth and within approximately 200 m from the lunar module. Two Luna 16 breccias are similar in composition to Luna 16 soils. Four Apollo 15 soils (LM, STA 4, 9, and 9a) have variable compositions. Interelement correlations between MnO-FeO, Sc-FeO, V-Cr2O3 and K2O-Hf negate the hypothesis that howardite achondrites may be primitive lunar matter, argue against the fission hypothesis for the origin of the moon, and precludes any selective large scale volatilization of alkalies during lunar magmatic events

    The Ursinus Weekly, March 18, 1940

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    Board elects Nicholas T. Barry new Ursinus Weekly editor • Weiland to edit 1941 Ruby ; Dubuque is business manager • Law and morals Goodrich\u27s subject • Candidates listed for April elections • C.A. Kulp talks on old-age security • Jr. ticket committee explains special price • Snyder sets April 2 for spring Lantern issue • Members of faculty quizzed in poll express sentiments on third term • 21-year voting age favored by students • Party is planned for conference week-end • I.R.C. quizzed on current events; will admit members • Committee heads are selected for women\u27s May Day pageant • Hal Moyer chosen honorary basketball captain for season • Ursinus players on all-star quintets • Infield and outfield candidates report • Dorm battlers vie Wednesday in gym • Frosh won five of twelve games • John DeBold wins conference trophy • Undefeated Temple beaten by co-eds • Conference committee secures two speakers • Vespers speaker points way to achieve true personality • Temple professor to address pre-medical society Tuesdayhttps://digitalcommons.ursinus.edu/weekly/1838/thumbnail.jp

    Design, Synthesis, and Biological Activity of 5\u27-Phenyl-1,2,5,6-tetrahydro-3,3\u27-bipyridine Analogues as Potential Antagonists of Nicotinic Acetylcholine Receptors

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    Starting from a known non-specific agonist (1) of nicotinic acetylcholine receptors (nAChRs), rationally guided structural-based design resulted in the discovery of a small series of 5′-phenyl-1,2,5,6-tetrahydro-3,3′-bipyridines (3a – 3e) incorporating a phenyl ring off the pyridine core of 1. The compounds were synthesized via successive Suzuki couplings on a suitably functionalized pyridine starting monomer 4 to append phenyl and pyridyl substituents off the 3- and 5-positions, respectively, and then make subsequent modifications on the flanking pyridyl ring to provide target compounds. Compound 3a is a novel antagonist which is highly selective for α3β4 nAChR (Ki = 123 nM) over the α4β2, and α7 receptors

    A class of well-posed parabolic final value problems

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    This paper focuses on parabolic final value problems, and well-posedness is proved for a large class of these. The clarification is obtained from Hilbert spaces that characterise data that give existence, uniqueness and stability of the solutions. The data space is the graph normed domain of an unbounded operator that maps final states to the corresponding initial states. It induces a new compatibility condition, depending crucially on the fact that analytic semigroups always are invertible in the class of closed operators. Lax--Milgram operators in vector distribution spaces constitute the main framework. The final value heat conduction problem on a smooth open set is also proved to be well posed, and non-zero Dirichlet data are shown to require an extended compatibility condition obtained by adding an improper Bochner integral.Comment: 16 pages. To appear in "Applied and numerical harmonic analysis"; a reference update. Conference contribution, based on arXiv:1707.02136, with some further development

    The observation of long-range three-body Coloumb effects in the decay of 16Ne

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    The interaction of an E/AE/A=57.6-MeV 17^{17}Ne beam with a Be target was used to populate levels in 16^{16}Ne following neutron knockout reactions. The decay of 16^{16}Ne states into the three-body 14^{14}O+pp+pp continuum was observed in the High Resolution Array (HiRA). For the first time for a 2p emitter, correlations between the momenta of the three decay products were measured with sufficient resolution and statistics to allow for an unambiguous demonstration of their dependence on the long-range nature of the Coulomb interaction. Contrary to previous experiments, the intrinsic decay width of the 16^{16}Ne ground state was found to be narrow (Γ<60\Gamma<60~keV), consistent with theoretical estimates.Comment: 6 pages, 5 figure

    Saturn's F Ring Core: Calm in the Midst of Chaos

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    The long-term stability of the narrow F Ring core has been hard to understand. Instead of acting as "shepherds", Prometheus and Pandora together stir the vast preponderance of the region into a chaotic state, consistent with the orbits of newly discovered objects like S/2004S6. We show how a comb of very narrow radial locations of high stability in semimajor axis is embedded within this otherwise chaotic region. The stability of these semimajor axes relies fundamentally on the unusual combination of rapid apse precession and long synodic period which characterizes the region. This situation allows stable "antiresonances" to fall on or very close to traditional Lindblad resonances which, under more common circumstances, are destabilizing. We present numerical integrations of tens of thousands of test particles over tens of thousands of Prometheus orbits that map out the effect. The stable antiresonance zones are most stable in a subset of the region where Prometheus first-order resonances are least cluttered by Pandora resonances. This region of optimum stability is paradoxically closer to Prometheus than a location more representative of "torque balance", helping explain a longstanding paradox. One stable zone corresponds closely to the currently observed semimajor axis of the F Ring core. While the model helps explain the stability of the narrow F Ring core, it does not explain why the F Ring material all shares a common apse longitude; we speculate that collisional damping at the preferred semimajor axis (not included in the current simulations) may provide that final step. Essentially, we find that the F Ring core is not confined by a combination of Prometheus and Pandora, but a combination of Prometheus and precession
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