899 research outputs found

    THE PORTRAYAL OF ANDREJ HLINKA IN SLOVAK HISTORIOGRAPHY

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    Th e paper analyzes the course of the process of historical research of the personality of Andrej Hlinka. One of the most signifi cant fi gures of the Slovak history in general became the subject of interest of the Slovak historians only gradually, slowly and with big diffi culties. Nevertheless, historians´ opinions which have been formed in particular period connections refl ect specifi - cally and typically the peripeties of the development of the Slovak national issue and phases of interest (disinterest) of historiography in this personality, and they represent a unique source of the view of collective historical memory of the national community, of the formally desired and naturally formed development of the community´s notion of the values of its own past.No historical monograph on Hlinka was published in 1939-1989. However, important references, period evaluations and observations can be found in synthetically oriented works of the following historians: František Hrušovský, František Bokes, Július Mésároš and Ľubomír Lipták and others. Th e personality of Hlinka was either suppressed or evaluated one-sidedly negatively. Th e year 1968 brought a certain change in this direction and revaluation of Hlinka’s personality. Th e period of normalization in 70s and 80s created a larger space to remember Hlinka’s personality, however, its interpretation was again shift ed towards negative side. The social and political change aft er 1989 and current state of research corroborate natural comeback of the personality in its environment, however, they also mirror a disproportion between spontaneously preserved “heritage of (the Slovak) historical memory” (heritage of the memory of majority of the national community, respectively) and institutionally created “memory of the heritage”.

    Spectral Properties of the Attractive Hubbard Model

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    Deviations from Fermi liquid behavior are well documented in the normal state of the cuprate superconductors, and some of these differences are possibly related to pre-formed pairs appearing at temperatures above T_c. In order to test these ideas we have investigated the attractive Hubbard model within a self-consistent, conserving ladder approximation. In this version of the theory, no feature is present which can be related to the pseudo gap found in the high-T_c materials. Further, the interactions between two-particle bound states change the physics of the superconducting instability in a profound fashion, and lead to a completely different phenomenology that one predicts based on the non-self-consistent version of the same theory.Comment: 4 pages including 2 figures, to appear in the proceedings of the SNS'9

    The electron gas with a strong pairing interaction: Three particle correlations and the Thouless instability

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    We derive simplified Faddeev type equations for the three particle T-matrix which are valid in the Hubbard model where only electrons with opposite spins interact. Using the approximation of dynamical mean field theory these equations are partially solved numerically for the attractive Hubbard model. It is shown that the three particle T-matrix contains a term vanishing T2\sim T^2 at the Thouless (or BCS) instability where the two-particle T-matrix diverges. Based on the three particle term we further derive the low density - strong coupling extension for the two-particle vertex function. We therefore understand our equations as a step towards a systematic low density expansion from the weak coupling BCS theory towards the stronger coupling limit.Comment: 14 pages, 9 figure

    Level statistics and localization in a 2D quantum percolation problem

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    A two dimensional model for quantum percolation with variable tunneling range is studied. For this purpose the Lifshitz model is considered where the disorder enters the Hamiltonian via the nondiagonal elements. We employ a numerical method to analyze the level statistics of this model. It turns out that the level repulsion is strongest around the percolation threshold. As we go away from the maximum level repulsion a crossover from a GOE type behavior to a Poisson like distribution is indicated. The localization properties are calculated by using the sensitivity to boundary conditions and we find a strong crossover from localized to delocalized states.Comment: 4 pages, 4 figure

    A geometric characterization of cc-optimal designs for heteroscedastic regression

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    We consider the common nonlinear regression model where the variance, as well as the mean, is a parametric function of the explanatory variables. The cc-optimal design problem is investigated in the case when the parameters of both the mean and the variance function are of interest. A geometric characterization of cc-optimal designs in this context is presented, which generalizes the classical result of Elfving [Ann. Math. Statist. 23 (1952) 255--262] for cc-optimal designs. As in Elfving's famous characterization, cc-optimal designs can be described as representations of boundary points of a convex set. However, in the case where there appear parameters of interest in the variance, the structure of the Elfving set is different. Roughly speaking, the Elfving set corresponding to a heteroscedastic regression model is the convex hull of a set of ellipsoids induced by the underlying model and indexed by the design space. The cc-optimal designs are characterized as representations of the points where the line in direction of the vector cc intersects the boundary of the new Elfving set. The theory is illustrated in several examples including pharmacokinetic models with random effects.Comment: Published in at http://dx.doi.org/10.1214/09-AOS708 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    On the theory of light scattering in molecular liquids

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    The theory of light scattering for a system of linear molecules with anisotropic polarizabilities is considered. As a starting point for our theory, we express the result of a scattering experiment in VV and VH symmetry as dynamic correlation functions of tensorial densities ρlm(q)\rho_{lm}(q) with l=0l=0 and l=2l=2. ll, mm denote indices of spherical harmonics. To account for all observed hydrodynamic singularities, a generalization of the theory of Schilling and Scheidsteger \cite{schilling97} for these correlation functions is presented, which is capable to describe the light scattering experiments from the liquid regime to the glassy state. As a microscopic theory it fulfills all sum rules contrary to previous {\em phenomenological} theories. We emphasize the importance of the helicity index mm for the microscopic theory by showing, that only the existence of m=1m=1 components lead to the well known Rytov dip in liquids and to the appearance of transversal sound waves in VH symmetry in the deeply supercooled liquid and the glass. Exact expressions for the phenomenological frequency dependent rotation translation coupling coefficients of previous theories are derived.Comment: 30 pages including 15 figures, submitted to EPJ B, revised version a detailed discussion on the depolarization ratio is added and the discussion on the hydrodynamic analysis is enlarge
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