735 research outputs found

    A log analysis study of 10 years of ebook consumption in academic library collections

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    Even though libraries have been offering eBooks for more than a decade, very little is known about eBook access and consumption in academic library collections. This paper addresses this gap with a log analysis study of eBook access at the library of the University of Waikato. This in-depth analysis covers a period spanning 10 years of eBook use at this university. We draw conclusions about the use of eBooks at this institution and compare the results with other published studies of eBook usage at tertiary institutes

    Synthesis of boronic ester γ‐lactam building blocks

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    Saturated heterocycles are found widely in biologically active compounds such as medicinal drugs and agrochemicals. However, boronic acid‐derived building blocks for these structures have limited availability, particularly in comparison to heteroaromatic boronic acids. We report the preparation of boronic ester γ‐lactams through a Cu‐catalysed conjugate borylation‐cyclisation protocol. Using a chiral catalyst, this can be performed in high enantioselectivity. Exploration of the further transformations of these reagents suggest that the boronic esters have much potential as chemical building blocks

    Optical properties of pyrochlore oxide Pb2Ru2O7−ήPb_{2}Ru_{2}O_{7-{\delta}}

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    We present optical conductivity spectra for Pb2Ru2O7−ήPb_{2}Ru_{2}O_{7-{\delta}} single crystal at different temperatures. Among reported pyrochlore ruthenates, this compound exhibits metallic behavior in a wide temperature range and has the least resistivity. At low frequencies, the optical spectra show typical Drude responses, but with a knee feature around 1000 \cm. Above 20000 \cm, a broad absorption feature is observed. Our analysis suggests that the low frequency responses can be understood from two Drude components arising from the partially filled Ru t2gt_{2g} bands with different plasma frequencies and scattering rates. The high frequency broad absorption may be contributed by two interband transitions: from occupied Ru t2gt_{2g} states to empty ege_{g} bands and from the fully filled O 2p bands to unoccupied Ru t2gt_{2g} states.Comment: 4 pages, 6 figure

    Very Low Temperature Tunnelling Spectroscopy in the heavy fermion superconductor PrOs4_4Sb12_{12}

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    We present scanning tunnelling spectroscopy measurements on the heavy fermion superconductor PrOs4_4Sb12_{12}. Our results show that the superconducting gap opens over a large part of the Fermi surface. The deviations from isotropic BCS s-wave behavior are discussed in terms of a finite distribution of values of the superconducting gap.Comment: 4 pages, 4 figure

    Pairing symmetry and long range pair potential in a weak coupling theory of superconductivity

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    We study the superconducting phase with two component order parameter scenario, such as, dx2−y2+eiΞsαd_{x^2-y^2} + e^{i\theta}s_{\alpha}, where α=xy,x2+y2\alpha = xy, x^2+y^2. We show, that in absence of orthorhombocity, the usual dx2−y2d_{x^2-y^2} does not mix with usual sx2+y2s_{x^2+y^2} symmetry gap in an anisotropic band structure. But the sxys_{xy} symmetry does mix with the usual d-wave for Ξ=0\theta =0. The d-wave symmetry with higher harmonics present in it also mixes with higher order extended ss wave symmetry. The required pair potential to obtain higher anisotropic dx2−y2d_{x^2-y^2} and extended s-wave symmetries, is derived by considering longer ranged two-body attractive potential in the spirit of tight binding lattice. We demonstrate that the dominant pairing symmetry changes drastically from dd to ss like as the attractive pair potential is obtained from longer ranged interaction. More specifically, a typical length scale of interaction Ο\xi, which could be even/odd multiples of lattice spacing leads to predominant s/ds/d wave symmetry. The role of long range interaction on pairing symmetry has further been emphasized by studying the typical interplay in the temperature dependencies of these higher order dd and ss wave pairing symmetries.Comment: Revtex 8 pages, 7 figures embeded in the text, To appear in PR

    Bessel Process and Conformal Quantum Mechanics

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    Different aspects of the connection between the Bessel process and the conformal quantum mechanics (CQM) are discussed. The meaning of the possible generalizations of both models is investigated with respect to the other model, including self adjoint extension of the CQM. Some other generalizations such as the Bessel process in the wide sense and radial Ornstein- Uhlenbeck process are discussed with respect to the underlying conformal group structure.Comment: 28 Page

    First Observation of Coherent π0\pi^0 Production in Neutrino Nucleus Interactions with EÎœ<E_{\nu}< 2 GeV

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    The MiniBooNE experiment at Fermilab has amassed the largest sample to date of π0\pi^0s produced in neutral current (NC) neutrino-nucleus interactions at low energy. This paper reports a measurement of the momentum distribution of π0\pi^0s produced in mineral oil (CH2_2) and the first observation of coherent π0\pi^0 production below 2 GeV. In the forward direction, the yield of events observed above the expectation for resonant production is attributed primarily to coherent production off carbon, but may also include a small contribution from diffractive production on hydrogen. Integrated over the MiniBooNE neutrino flux, the sum of the NC coherent and diffractive modes is found to be (19.5 ±\pm1.1 (stat) ±\pm2.5 (sys))% of all exclusive NC π0\pi^0 production at MiniBooNE. These measurements are of immediate utility because they quantify an important background to MiniBooNE's search for ΜΌ→Μe\nu_{\mu} \to \nu_e oscillations.Comment: Submitted to Phys. Lett.
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