167 research outputs found

    Scepticism and ironic correlations in the joy statements of Qoheleth?

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    This Ph.D. dissertation examines the seven joy statements in the Book of Qoheleth (2.24-25; 3.12-13; 3.22; 5.17-19; 8.15; 9.7-9; 11.8-9) in order to understand their literary nature and effects. The thesis question which this dissertation attempts to answer is: Can scepticism and ironic correlations be found in the joy statements of Qoheleth? After examining the thesis question, the conclusion was drawn (thesis): Even if there is no scepticism in the joy statements of Qoheleth, one must be sceptical about any interpretation of them. In other words: Any reading of the joy statements in Qoheleth must be viewed as indeterminate. This conclusion was drawn not only on the basis of the literary nature and effects of the joy statements alone, which were indeterminate, but in the light of scepticism as a philosophy and because of possible correlations with irony. The methodology for examining the thesis question is progressive. Each chapter of the dissertation provides additional information from the most basic upwards in an attempt to answer the question. Each chapter and section are critically assessed and conclusions drawn. The methodology of this dissertation is as follows: Chapter one provides a careful analysis of key terms in Qoheleth: Chapter two provides a detailed exegesis of the joy statements. Chapter three provides a form critical analysis of the joy statements with special attention to their literary form in the overall literary structure of the book and within their overall (1.12-2.26; 3.1-15; 3.15-22; 5.7-6.9; 8.1-10.20; 9.1-12; 11.7-12.7) and immediate (2.17-26; 3.9-15; 3.18-22; 5.15-6.2; 8.10-17; 9.7-10; 11.8-9) contexts, additional exegetical notes, and with reference to Qoheleth's overall content and ethos. Chapter four provides an overview of the philosophy of scepticism and the view there is a sceptical traditional in the Hebrew Bible

    Mesoscopic fluctuations of Coulomb drag between quasi-ballistic 1D-wires

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    Quasiballistic 1D quantum wires are known to have a conductance of the order of 2e^2/h, with small sample-to-sample fluctuations. We present a study of the transconductance G_12 of two Coulomb-coupled quasiballistic wires, i.e., we consider the Coulomb drag geometry. We show that the fluctuations in G_12 differ dramatically from those of the diagonal conductance G_ii: the fluctuations are large, and can even exceed the mean value, thus implying a possible reversal of the induced drag current. We report extensive numerical simulations elucidating the fluctuations, both for correlated and uncorrelated disorder. We also present analytic arguments, which fully account for the trends observed numerically.Comment: 10 pages including 7 figures. Minor changes according to referee report. Accepted for PR

    Quantum dots with two electrons: Singlet-triplet transitions

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    The magnetic character of the ground-state of two electrons on a double quantum dot, connected in series to left and right single-channel leads, is considered. By solving exactly for the spectrum of the two interacting electrons, it is found that the coupling to the continuum of propagating states on the leads, in conjunction with the electron-electron interactions, may result in a delocalization of the bound state of the two electrons. This, in turn, reduces significantly the range of the Coulomb interaction parameters over which singlet-triplet transitions can be realized. It is also found that the coupling to the leads favors the singlet ground-state.Comment: 8 pages, submitted to Phys. Rev.

    Q-dependence of the inelastic neutron scattering cross section for molecular spin clusters with high molecular symmetry

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    For powder samples of polynuclear metal complexes the dependence of the inelastic neutron scattering intensity on the momentum transfer Q is known to be described by a combination of so called interference terms. They reflect the interplay between the geometrical structure of the compound and the spatial properties of the wave functions involved in the transition. In this work, it is shown that the Q-dependence is strongly interrelated with the molecular symmetry of molecular nanomagnets, and, if the molecular symmetry is high enough, is actually completely determined by it. A general formalism connecting spatial symmetry and interference terms is developed. The arguments are detailed for cyclic spin clusters, as experimentally realized by e.g. the octanuclear molecular wheel Cr8, and the star like tetranuclear cluster Fe4.Comment: 8 pages, 1 figures, REVTEX

    Resistivity of a Metal between the Boltzmann Transport Regime and the Anderson Transition

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    We study the transport properties of a finite three dimensional disordered conductor, for both weak and strong scattering on impurities, employing the real-space Green function technique and related Landauer-type formula. The dirty metal is described by a nearest neighbor tight-binding Hamiltonian with a single s-orbital per site and random on-site potential (Anderson model). We compute exactly the zero-temperature conductance of a finite size sample placed between two semi-infinite disorder-free leads. The resistivity is found from the coefficient of linear scaling of the disorder averaged resistance with sample length. This ``quantum'' resistivity is compared to the semiclassical Boltzmann expression computed in both Born approximation and multiple scattering approximation.Comment: 5 pages, 3 embedded EPS figure

    Magnetic Field Effects on the Transport Properties of One-sided Rough Wires

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    We present a detailed numerical analysis of the effect of a magnetic field on the transport properties of a `small-NN' one-sided surface disordered wire. When time reversal symmetry is broken due to a magnetic field BB, we find a strong increase with BB not only of the localization length Îľ\xi but also of the mean free path â„“\ell caused by boundary states. Despite this, the universal relationship between â„“\ell and Îľ\xi does hold. We also analyze the conductance distribution at the metal-insulator crossover, finding a very good agreement with Random Matrix Theory with two fluctuating channels within the Circular Orthogonal(Unitary) Ensemble in absence(presence) of BBComment: 5 pages, 4 figures, to appear in Phys. Rev.

    Views of the Chiral Magnetic Effect

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    My personal views of the Chiral Magnetic Effect are presented, which starts with a story about how we came up with the electric-current formula and continues to unsettled subtleties in the formula. There are desirable features in the formula of the Chiral Magnetic Effect but some considerations would lead us to even more questions than elucidations. The interpretation of the produced current is indeed very non-trivial and it involves a lot of confusions that have not been resolved.Comment: 19 pages, no figure; typos corrected, references significantly updated, to appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

    Universal Correlations of Coulomb Blockade Conductance Peaks and the Rotation Scaling in Quantum Dots

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    We show that the parametric correlations of the conductance peak amplitudes of a chaotic or weakly disordered quantum dot in the Coulomb blockade regime become universal upon an appropriate scaling of the parameter. We compute the universal forms of this correlator for both cases of conserved and broken time reversal symmetry. For a symmetric dot the correlator is independent of the details in each lead such as the number of channels and their correlation. We derive a new scaling, which we call the rotation scaling, that can be computed directly from the dot's eigenfunction rotation rate or alternatively from the conductance peak heights, and therefore does not require knowledge of the spectrum of the dot. The relation of the rotation scaling to the level velocity scaling is discussed. The exact analytic form of the conductance peak correlator is derived at short distances. We also calculate the universal distributions of the average level width velocity for various values of the scaled parameter. The universality is illustrated in an Anderson model of a disordered dot.Comment: 35 pages, RevTex, 6 Postscript figure
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