32,165 research outputs found

    Enhancing Undergraduate Education: Examining Faculty Experiences During Their First Year in a Residential College and Exploring the Implications for Student Affairs Professionals

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    The article discusses the results of a study on the experiences and insights of faculty members in a new residential college. The researchers used a constructivist, case study method to determine how faculty made meaning of their experiences in a residential college at a major, land-grant research university in the Midwest U.S. The findings of the study indicate that the residential college environment did not ameliorate the time pressures experienced by faculty

    A Back-reaction Induced Lower Bound on the Tensor-to-Scalar Ratio

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    There are large classes of inflationary models, particularly popular in the context of string theory and brane world approaches to inflation, in which the ratio of linearized tensor to scalar metric fluctuations is very small. In such models, however, gravitational waves produced by scalar modes cannot be neglected. We derive the lower bound on the tensor-to-scalar ratio by considering the back-reaction of the scalar perturbations as a source of gravitational waves. These results show that no cosmological model that is compatible with a metric scalar amplitude of 105\approx 10^{-5} can have a ratio of the tensor to scalar power spectra less than 108\approx 10^{-8} at recombination and that higher-order terms leads to logarithmic growth for r during radiation domination. Our lower bound also applies to non-inflationary models which produce an almost scale-invariant spectrum of coherent super-Hubble scale metric fluctuations.Comment: 5 pages, version 3, minor changes from version

    Solutions of the Yang-Baxter Equation with Extra Non-Additive Parameters II: Uq(gl(mn))U_q(gl(m|n))}

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    The type-I quantum superalgebras are known to admit non-trivial one-parameter families of inequivalent finite dimensional irreps, even for generic qq. We apply the recently developed technique to construct new solutions to the quantum Yang-Baxter equation associated with the one-parameter family of irreps of Uq(gl(mn))U_q(gl(m|n)), thus obtaining R-matrices which depend not only on a spectral parameter but in addition on further continuous parameters. These extra parameters enter the Yang-Baxter equation in a similar way to the spectral parameter but in a non-additive form.Comment: 10 pages, LaTex file (some errors in the Casimirs corrected

    On Type-I Quantum Affine Superalgebras

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    The type-I simple Lie-superalgebras are sl(mn)sl(m|n) and osp(22n)osp(2|2n). We study the quantum deformations of their untwisted affine extensions Uq(sl(mn)(1))U_q(sl(m|n)^{(1)}) and Uq(osp(22n)(1))U_q(osp(2|2n)^{(1)}). We identify additional relations between the simple generators (``extra qq-Serre relations") which need to be imposed to properly define \uqgh and Uq(osp(22n)(1))U_q(osp(2|2n)^{(1)}). We present a general technique for deriving the spectral parameter dependent R-matrices from quantum affine superalgebras. We determine the R-matrices for the type-I affine superalgebra Uq(sl(mn)(1))U_q(sl(m|n)^{(1)}) in various representations, thereby deriving new solutions of the spectral-dependent Yang-Baxter equation. In particular, because this algebra possesses one-parameter families of finite-dimensional irreps, we are able to construct R-matrices depending on two additional spectral-like parameters, providing generalizations of the free-fermion model.Comment: 23 page

    Braneworlds, Conformal Fields and the Gravitons

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    We investigate the dynamics of Randall-Sundrum AdS5 braneworlds with 5-dimensional conformal matter fields. In the scenario with a compact fifth dimension the class of conformal fields with weight -4 is associated with exact 5-dimensional warped geometries which are stable under radion field perturbations and describe on the brane the dynamics of inhomogeneous dust, generalized dark radiation and homogeneous polytropic dark energy. We analyse the graviton mode flutuations around this class of background solutions and determine their mass eigenvalues and wavefunctions from a Sturm-Liouville problem. We show that the localization of gravity is not sharp enough for large mass hierarchies to be generated. We also discuss the physical bounds imposed by experiments in particle physics, in astrophysics and in precise measurements of the low energy gravitational interaction.Comment: LaTeX, 9 pages, 2 figures. Based on talk given in the Second International Conference on Quantum Theories and the Renormalization Group in Gravity and Cosmology, CSIC and University of Barcelona, Barcelona, Spain, 11-15 July 2006. Submitted to be published in the Conference Proceedings, J. Phys. A: Math. Ge

    Influence of low-level Pr substitution on the superconducting properties of YBa2Cu3O7-delta single crystals

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    We report on measurements on Y1-xPrxBa2Cu3O7-delta single crystals, with x varying from 0 to 2.4%. The upper and the lower critical fields, Hc2 and Hc1, the Ginzburg-Landau parameter and the critical current density, Jc(B), were determined from magnetization measurements and the effective media approach scaling method. We present the influence of Pr substitution on the pinning force density as well as on the trapped field profiles analyzed by Hall probe scanning.Comment: 4 pages, 5 figures, accepted for publication in J. Phys. Conf. Se

    Precise dispersive data analysis of the f0(600) pole

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    We review how the use of recent precise data on kaon decays together with forward dispersion relations (FDR) and Roy's equations allow us to determine the sigma resonance pole position very precisely, by using only experimental input. In addition, we present preliminary results for a modified set of Roy-like equations with only one subtraction, that show a remarkable improvement in the precision around the sigma region. We also improve the matching between the parametrizations at low and intermediate energy of the S0 wave, and show that the effect of this on the sigma pole position is negligible.Comment: 4 pages, 1 figure. To appear in the proceedings of the Meson 2008 conference, June 6-10, Cracow, Polan

    Transient Astrophysical Pulses and Quantum Gravity

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    Searches for transient astrophysical pulses could open an exciting new window into the fundamental physics of quantum gravity. In particular, an evaporating primordial black hole in the presence of an extra dimension can produce a detectable transient pulse. Observations of such a phenomenon can in principle explore the electroweak energy scale, indicating that astrophysical probes of quantum gravity can successfully complement the exciting new physics expected to be discovered in the near future at the Large Hadron Collider.Comment: 7 pages, This essay received an honorable mention in the Gravity Research Foundation Essay Competition, 200
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