1,482 research outputs found

    Stratigraphic evolution of the Jurassic, Moray Firth.

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    Establishing a Review Process to Evaluate Research Guides

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    Springshare\u27s LibGuide platform has become synonymous with online library pathfinders or research guides and instruction support. However, without oversight of the collection of guides and standards for their creation, unwieldy numbers and lack of uniformity prevail. The McGoogan Library of Medicine at the University of Nebraska Medical Center created a review process that not only governed the creation and approval of guides, but analyzed the usage and scope of guides that had already been created. This paper will outline the creation of standards and application of a review process to increase the value and relevance of guides

    Duality between Electric and Magnetic Black Holes

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    A number of attempts have recently been made to extend the conjectured SS duality of Yang Mills theory to gravity. Central to these speculations has been the belief that electrically and magnetically charged black holes, the solitons of quantum gravity, have identical quantum properties. This is not obvious, because although duality is a symmetry of the classical equations of motion, it changes the sign of the Maxwell action. Nevertheless, we show that the chemical potential and charge projection that one has to introduce for electric but not magnetic black holes exactly compensate for the difference in action in the semi-classical approximation. In particular, we show that the pair production of electric black holes is not a runaway process, as one might think if one just went by the action of the relevant instanton. We also comment on the definition of the entropy in cosmological situations, and show that we need to be more careful when defining the entropy than we are in an asymptotically-flat case.Comment: 23 pages, revtex, no figures. Major revision: two sections on the electric Ernst solution adde

    Radiative Capture of Tensor Polarized Deuterons on Hydrogen Isotopes

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Effect of continuum couplings in fusion of halo 11^{11}Be on 208^{208}Pb around the Coulomb barrier

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    The effect of continuum couplings in the fusion of the halo nucleus 11^{11}Be on 208^{208}Pb around the Coulomb barrier is studied using a three-body model within a coupled discretised continuum channels (CDCC) formalism. We investigate in particular the role of continuum-continuum couplings. These are found to hinder total, complete and incomplete fusion processes. Couplings to the projectile 1p1/21p_{1/2} bound excited state redistribute the complete and incomplete fusion cross sections, but the total fusion cross section remains nearly constant. Results show that continuum-continuum couplings enhance the irreversibility of breakup and reduce the flux that penetrates the Coulomb barrier. Converged total fusion cross sections agree with the experimental ones for energies around the Coulomb barrier, but underestimate those for energies well above the Coulomb barrier.Comment: 15 pages, 7 figures, accepted in Phys. Rev.

    On Modular Homology of Simplicial Complexes: Saturation

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    ... homology, and these are the so-called saturated complexes. We show that certain conditions on the links of the complex imply saturation. We prove that Coxeter complexes and buildings are saturated

    Tensor Polarized Deuteron Capture by the Hydrogen Isotopes

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Tensor Polarized Deuteron Capture by the Hydrogen Isotopes

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Review article: MHD wave propagation near coronal null points of magnetic fields

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    We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfven wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfven-speed profile. In a β=0\beta=0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfven wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfven wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfven wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note this is a 2011 paper, not a 2010 pape

    Numerical investigation of breast tumour detection using multi-static radar

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