80,505 research outputs found

    Coke of Norfolk 1754-1842: a biography by Susanna Wade Martins [2009]

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    Susanna Wade Martins, Coke of Norfolk, 1754–1842. A Biography, Woodbridge, Suffolk, The Boydell Press, 2009. xii + 218 pp. £50.00. 9781843834267. This biography does Thomas Coke full justice, in style as well as in content. It is excellently illustrated with colour and monochrome plates with helpful, discursive captions and specially drawn maps and diagrams. The bibliography and index are extensive and the book has been meticulously produced. Coke’s memory is well served by this first-rate piece of work

    Self-similar static solutions admitting a two-space of constant curvature

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    A recent result by Haggag and Hajj-Boutros is reviewed within the framework of self-similar space-times, extending, in some sense, their results and presenting a family of metrics consisting of all the static spherically symmetric perfect fluid solutions admitting a homothety.Comment: 6 page

    On the Theory of Killing Orbits in Space-Time

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    This paper gives a theoretical discussion of the orbits and isotropies which arise in a space-time which admits a Lie algebra of Killing vector fields. The submanifold structure of the orbits is explored together with their induced Killing vector structure. A general decomposition of a space-time in terms of the nature and dimension of its orbits is given and the concept of stability and instability for orbits introduced. A general relation is shown linking the dimensions of the Killing algebra, the orbits and the isotropies. The well-behaved nature of "stable" orbits and the possible miss-behaviour of the "unstable" ones is pointed out and, in particular, the fact that independent Killing vector fields in space-time may not induce independent such vector fields on unstable orbits. Several examples are presented to exhibit these features. Finally, an appendix is given which revisits and attempts to clarify the well-known theorem of Fubini on the dimension of Killing orbits.Comment: Latex, 19 pages, no figur

    A low‐noise high‐speed diode laser current controller

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    We describe a new diode laser current controller which features low current noise, excellent dc stability, and the capacity for high‐speed modulation. While it is simple and inexpensive to construct, the controller compares favorably with the best presently available commercial diode laser current controllers

    The principle of equivalence and projective structure in space-times

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    This paper discusses the extent to which one can determine the space-time metric from a knowledge of a certain subset of the (unparametrised) geodesics of its Levi-Civita connection, that is, from the experimental evidence of the equivalence principle. It is shown that, if the space-time concerned is known to be vacuum, then the Levi-Civita connection is uniquely determined and its associated metric is uniquely determined up to a choice of units of measurement, by the specification of these geodesics. It is further demonstrated that if two space-times share the same unparametrised geodesics and only one is assumed vacuum then their Levi-Civita connections are again equal (and so the other metric is also a vacuum metric) and the first result above is recovered.Comment: 23 pages, submitted to Classical and Quantum Gravit

    A Study for a Tracking Trigger at First Level for CMS at SLHC

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    It is expected that the LHC accelerator and experiments will undergo a luminosity upgrade which will commence after several years of running. This part of the LHC operations is referred to as Super-LHC (SLHC) and is expected to provide beams of an order of magnitude larger luminosity (1035cm-2sec-1) than the current design. Preliminary results are presented from a feasibility study for a First Level Tracking Trigger for CMS at the SLHC using the data of the inner tracking detector. As a model for these studies the current CMS pixel detector with the same pixel size and radial distances from the beam has been used. Monte Carlo studies have been performed using the full CMS simulation package (OSCAR) and the occupancy of such a detector at SLHC beam conditions has been calculated. The design of an electron trigger which uses both the calorimeter energy depositions and the pixel data to identify isolated electrons and photons has been investigated. Results on the tracker occupancy and the electron trigger performance are presentedComment: Presented at LECC, Heidelberg 200

    On the general structure of Ricci collineations for type B warped spacetimes

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    A complete study of the structure of Ricci collineations for type B warped spacetimes is carried out. This study can be used as a method to obtain these symetries in such spacetimes. Special cases as 2+2 reducible spacetimes, and plane and spherical symmetric spacetimes are considered specifically.Comment: 18 pages. Version accepted for publication in JM

    Palladium, platinum, and gold distribution in serpentinite seamounts in the Mariana and Izu-Bonin forearcs: evidence from Leg 125 fluids and serpentinites

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    Palladium, platinum, and gold were analyzed for 20 interstitial water samples from Leg 125. No Pd or Pt was detected in fluids from serpentinite muds from Conical Seamount in the Mariana forearc, indicating that low-temperature seawater-peridotite interaction does not mobilize these elements into the serpentinizing fluids to levels above 0.10 parts per billion (ppb) in solution. However, Au may be mobilized in high pH solutions. In contrast, fluids from vitric-rich clays on the flanks of the Torishima Seamount in the Izu-Bonin forearc have Pd values of between 4.0 and 11.8 nmol/L, Pt values between 2.3 and 5.0 nmol/L and Au values between 126.9 and 1116.9 pmol/L. The precious metals are mobilized, and possibly adsorbed onto clay mineral surfaces, during diagenesis and burial of the volcanic-rich clays. Desorption during squeezing of the sediments may produce the enhanced precious metal concentrations in the analyzed fluids. The metals are mobilized in the fluids probably as neutral hydroxide, bisulfide, and ammonia complexes. Pt/Pd ratios are between 0.42 and 2.33, which is much lower than many of the potential sources for Pt and Pd but is consistent with the greater solubility of Pd compared with Pt in most natural low-temperature fluids

    Recent Studies of Nonequilibrium Flows at the Cornell Aeronautical Laboratory

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    Vibrational relaxation in supersonic nozzle diatomic gas flow, nonequilibrium effects in high enthalpy airflow over thick wedge flat plates, and reentry nonequilibrium flow field
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