63,922 research outputs found

    RR Lyrae stars in the outer region of the globular cluster M3: a shortage of long periods at r ~ 3.5 to 6 arcmin ?

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    An analysis of the radial distribution of ab-type RR Lyrae star periods in the outer region of the globular cluster M3 at r >= 0.83 arcmin has been performed. That analysis points towards a real shortage of stars with long periods in the radial distance range 3.5 to 6 arcmin (or about 7 to 12 core radii). A brief discussion is presented. The origin of the phenomenon remains an open question.Comment: 3 pages, 2 figures, Accepted for publication in A&

    The Rising Tide of Expertise

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    Forum: Teaching the Future Rich: How to Best Give Money

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    Proving Foreign Documents in New York

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    Microscopes and computers combined for analysis of chromosomes

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    Scanning machine CHLOE, developed for photographic use, is combined with a digital computer to obtain quantitative and statistically significant data on chromosome shapes, distribution, density, and pairing. CHLOE permits data acquisition about a chromosome complement to be obtained two times faster than by manual pairing

    Can tract element distributions reclaim tectonomagmatic facies of basalts in greenstone assemblages?

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    During the past two decades many words have been written both for and against the hypothesis that the tectonic setting of a suite of igneous rocks is retained by the chemical variability within the suite. For example, it is argued that diagrams can be constructed from modern/recent basalt subcompositions within the system Ti-Zr-Y-Nb-Sr such that tectonomagmatic settings can be reclaimed. If one accepts this conclusion, it is tempting to inquire as to how far this hypothesis can be extended into other petrological realms. If chemical variations of metabasalts retain information relating to their genesis (tectonic setting), for example, this would be most helpful in reconstructing the history of basalts from greenstone belts. A discussion follows

    The Penn Science Teacher Institute: A Proven Model

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    The University of Pennsylvania’s Master of Chemistry Education (MCE) program graduated five cohorts of approximately twenty teachers between 2002 and 2006. One year after the teachers in the last cohort earned their degrees, the Penn Science Teacher Institute (Penn STI) initiated a follow-up study to ascertain if the goals of the MCE program had been sustained. For example, were the teachers incorporating updated content knowledge into their lessons and were their students learning more chemistry? A total of seventy-four of the eighty-two graduates participated in some aspect of this study. Because baseline data were not available for the MCE teachers and their students, baseline data from a comparable group of chemistry teachers enrolled in the first cohort of the Penn STI program and their students were used in some analyses. Among other findings, the data indicate that MCE met its goals: 1) to improve the chemistry content knowledge of its teacher participants; 2) to increase the use of research-based instruction in their classrooms; and, 3) to improve student achievement in chemistry (students of MCE graduates scored significantly higher than the comparison group)

    Probing Hadronic Structure with The Decay ΔNl+l\Delta\rightarrow Nl^+l^-

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    We compute the branching ratio for ΔNe+e\Delta\rightarrow Ne^+e^- and ΔNμ+μ\Delta\rightarrow N\mu^+\mu^- in chiral perturbation theory and find that both decays should be observable at CEBAF. With sufficiently low thresholds on the e+ee^+e^- invariant mass a branching ratio of 105\sim 10^{-5} may be observed for ΔNe+e\Delta\rightarrow Ne^+e^-. For the ΔNμ+μ\Delta\rightarrow N\mu^+\mu^- decay mode we predict a branching ratio of 3×1073\times 10^{-7}. The dependence of the M1 and E2 amplitudes on the momentum transfer will provide a useful test of chiral perturbation theory which predicts 20%\sim 20\% variation over the allowed kinematic range.Comment: 6 pages, 3 figures, UCSD/PTH 93-06, QUSTH-93-02, Duke-TH-93-4
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