17,136 research outputs found

    A Peak Point Theorem for Uniform Algebras on Real-Analytic Varieties

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    It was once conjectured that if AA is a uniform algebra on its maximal ideal space XX, and if each point of XX is a peak point for AA, then A=C(X)A = C(X). This peak-point conjecture was disproved by Brian Cole in 1968. Here we establish a peak-point theorem for uniform algebras generated by real-analytic functions on real-analytic varieties, generalizing previous results of the authors and John Wermer

    Gender Equity in Intercollegiate Athletics: Determinants of Title IX Compliance

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    Using new data on intercollegiate athletes, this article shows that recent improvement in Title IX compliance among NCAA Division I institutions was previously overestimated, and provides the first estimates of compliance in Divisions II and III. In addition, regression analyses investigate how institutional characteristics relate to the extent of non-compliance

    Factor Price Disparity in the Feeder Cattle Market and Retained Ownership Decision Making: An Application of Farm-Level Feed-Out Data

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    This study uses farm-level data from a university feed-out program to evaluate how the value of feeder cattle ultimately realized through finishing and grid pricing differs from their market value at public auction. Results indicate that uncertainty related to feedlot performance, final carcass merits, and fed cattle prices likely contribute to significant risk premiums in the feeder cattle market. This is consistent with the theory of factor price disparity. This result indicates that producers of cattle with known feedlot performance and/or carcass potential may be better off retaining ownership of their calves or marketing them in a way that communicates the information that is known about their potential performance directly to the buyer.Marketing,

    How credible are capital spending surveys as forecasts?

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    A comparison of the reliability of the Commerce Department's capital spending survey with that of several alternative forecasts.Capital investments ; Forecasting

    The divergence characteristics of constrained-sheath optics systems for use with 5-eV atomic oxygen sources

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    The potential usefulness of the constrained sheath optics concept as a means of controlling the divergence of low energy, high current density ion beams is examined numerically and experimentally. Numerical results demonstrate that some control of the divergence of typical ion beamlets can be achieved at perveance levels of interest by contouring the surface of the constrained sheath properly. Experimental results demonstrate that a sheath can be constrained by a wire mesh attached to the screen plate of the ion optics system. The numerically predicted beamlet divergence characteristics are shown to depart from those measured experimentally, and additional numerical analysis is used to demonstrate that this departure is probably due to distortions of the sheath caused by the fact that it attempts to conform to the individual wires that make up the sheath constraining mesh. The concept is considered potentially useful in controlling the divergence of ion beamlets in applications where low divergence, low energy, high current density beamlets are being sought, but more work is required to demonstrate this for net beam ion energies as low as 5 eV

    Modular vector fields attached to Dwork family: sl2(C)\mathfrak{sl}_2(\mathbb{C}) Lie algebra

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    We introduce an algebraic group G\sf G that acts from right on the moduli space T\textsf{T} of Calabi-Yau nn-folds arising from Dwork family enhanced with differential forms, and describe its Lie algebra Lie(G){\rm Lie}({\sf G}). We observe that Lie(G){\rm Lie}({\sf G}) together with a modular vector field R{\sf R} on T\textsf{T} generates another Lie algebra G\mathfrak{G}, called AMSY-Lie algebra, such that dimG=dimT\dim \mathfrak{G}=\dim {\sf T}. We find sl2(C)\mathfrak{sl}_2(\mathbb{C}) as a Lie subalgebra of G\mathfrak{G} that contains R\sf R.Comment: 20 page

    A Mission to Test the Pioneer Anomaly

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    Analysis of the radio tracking data from the Pioneer 10/11 spacecraft has consistently indicated the presence of an anomalous small Doppler frequency drift. The drift can be interpreted as being due to a constant acceleration of a_P= (8.74 +/- 1.33) x 10^{-8} cm/s^2 directed towards the Sun. Although it is suspected that there is a systematic origin to the effect, none has been found. The nature of this anomaly has become of growing interest in the fields of relativistic cosmology, astro- and gravitational physics as well as in the areas of spacecraft design and high-precision navigation. We present a concept for a designated deep-space mission to test the discovered anomaly. A number of critical requirements and design considerations for such a mission are outlined and addressed.Comment: Final changes for publication. Honorable Mention, 2002 Gravity Research Foundation Essay

    Chameleon effect and the Pioneer anomaly

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    The possibility that the apparent anomalous acceleration of the Pioneer 10 and 11 spacecraft may be due, at least in part, to a chameleon field effect is examined. A small spacecraft, with no thin shell, can have a more pronounced anomalous acceleration than a large compact body, such as a planet, having a thin shell. The chameleon effect seems to present a natural way to explain the differences seen in deviations from pure Newtonian gravity for a spacecraft and for a planet, and appears to be compatible with the basic features of the Pioneer anomaly, including the appearance of a jerk term. However, estimates of the size of the chameleon effect indicate that its contribution to the anomalous acceleration is negligible. We conclude that any inverse-square component in the anomalous acceleration is more likely caused by an unmodelled reaction force from solar-radiation pressure, rather than a chameleon field effect.Comment: 16 pages; to appear in Phys.Rev.
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