854,438 research outputs found

    Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly

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    Analysis of the radio-metric tracking data from the Pioneer 10/11 spacecraft at distances between 20--70 astronomical units (AU) from the Sun has consistently indicated the presence of an anomalous, small, constant Doppler frequency drift. The drift is a blue-shift, uniformly changing with rate a_t = (2.92 +/- 0.44) x 10^(-18) s/s^2. It can also be interpreted as 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. As a result, the nature of this anomaly has become of growing interest. Here we discuss the details of our recent investigation focusing on the effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques. We review some of the mechanisms proposed to explain the anomaly and show their inability to account for the observed behavior of the anomaly. We also present lessons learned from this investigation for a potential deep-space experiment that will reveal the origin of the discovered anomaly and also will characterize its properties with an accuracy of at least two orders of magnitude below the anomaly's size. A number of critical requirements and design considerations for such a mission are outlined and addressed.Comment: 11 pages, invited talk given at ``35th COSPAR Scientific Assebly,'' July 18-24, 2004, Paris, Franc

    On an SO(5) unification attempt for the cuprates

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    In this note we bring out several problems with the SO(5) unification attempt of Zhang [cond-mat/9610140].Comment: 3 pages, latex (revtex

    Variational Principles for Natural Divergence-free Tensors in Metric Field Theories

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    Let Tab=Tba=0T^{ab}=T^{ba}=0 be a system of differential equations for the components of a metric tensor on RmR^m. Suppose that TabT^{ab} transforms tensorially under the action of the diffeomorphism group on metrics and that the covariant divergence of TabT^{ab} vanishes. We then prove that TabT^{ab} is the Euler-Lagrange expression some Lagrangian density provided that TabT^{ab} is of third order. Our result extends the classical works of Cartan, Weyl, Vermeil, Lovelock, and Takens on identifying field equations for the metric tensor with the symmetries and conservation laws of the Einstein equations

    Model construction for decision support systems for beef stations

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    Decision Support System (DSS)

    Heart-rate pulse-shift detector

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    Detector circuit accurately separates and counts phase-shift pulses over wide range of basic pulse-rate frequency, and also provides reasonable representation of full repetitive EKG waveform. Single telemeter implanted in small animal monitors not only body temperature but also animal movement and heart rate

    Geometry, EFE's and Foundations for Brane Cosmology

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    I argue that GR Cauchy and Initial Value Problem mathematics is a valuable source of ideas for braneworlds based on higher-dimensional Einstein field equations.Comment: 2 pages, to appear in Proceedings of Rio de Janeiro 2003 Marcel Grossmann Meetin
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