854,438 research outputs found
Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly
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
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
Let be a system of differential equations for the
components of a metric tensor on . Suppose that transforms
tensorially under the action of the diffeomorphism group on metrics and that
the covariant divergence of vanishes. We then prove that is
the Euler-Lagrange expression some Lagrangian density provided that 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
Decision Support System (DSS)
Heart-rate pulse-shift detector
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
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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