1,309 research outputs found

    Large non-adiabatic hole polarons and matrix element effects in the angle-resolved photoemission spectroscopy of dielectric cuprates

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    It has been made an extention of the conventional theory based on the assumption of the well isolated Zhang-Rice singlet to be a first electron-removal state in dielectric copper oxide. One assumes the photohole has been localised on either small (pseudo)Jahn-Teller polaron or large non-adiabatic polaron enclosed one or four to five CuO4CuO_4 centers, respectively, with active one-center valent (1A1g1,3Eu)(^{1}A_{1g}-{}^{1,3}E_{u}) manifold. In the framework of the cluster model we have performed a model microscopic calculation of the k{\bf k}-dependence of the matrix element effects and photon polarization effects for the angle-resolved photoemission in dielectric cuprate like Sr2CuO2Cl2Sr_{2}CuO_{2}Cl_{2}. We show that effects like the ''remnant Fermi surface'' detected in ARPES experiment for Ca2CuO2Cl2Ca_{2}CuO_{2}Cl_{2} may be, in fact, a reflection of the matrix element effects, not a reflection of the original band-structure Fermi surface, or the strong antiferromagnetic correlations. The measured dispersion-like features in the low-energy part of the ARPES spectra may be a manifestation of the complex momentum-dependent spectral line-shape of the large PJT polaron response, not the dispersion of the well-isolated Zhang-Rice singlet in antiferromagnetic matrix.Comment: 16 pages, TeX, 9 eps figures adde

    ПРИНЦИПИ УТВОРЕННЯ ПАРАМЕТРИЧНИХ ВУЗЛІВ КІНЦЕВОГО ПУНКТУ КЕРУЮЧОЇ СИСТЕМИ ТРАНСПОРТНОГО ЗАСОБУ, НЕУКОМПЛЕКТОВАНОГО АНТЕННОЮ ДЛЯ ПОЛЬОТУ

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    The principles of formation of the vector of distance D from unmanned aerial vehicle UAV to transponderbeacon,and its velocity V­­k, which are necessary for on board calculation of the UAV motion parameters.Показанны принципы формирования векторов дальности D от беспилотного летательного аппарата к маяку- ответчику,его скорость к V­­k, необходимые для вычисления на борту БПЛА параметров его движения.Показані принципи формування векторів дальності D від безпілотного літального апарату до маяка-відповідача ,та його швидкості V­­k , необхідної для обчислення на борту БПЛА параметра його руху

    Shaping of cutting part of angle milling cutters with nonzero geometry

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    Angle milling cutters with zero and nonzero geometry have been analyzed, as well as their advantages and disadvantages. Analysis of methods of treating cutting part of angle cutters has been made. The shaping process of cutting parts of angle milling cutters with non-zero geometry has been discussed in detail. Issues of designing these angle cutters have been considered and dependencies have been shown for defining their geometric parameters as well as the parameters required for machine setup for manufacturing the cutters. © IDOSI Publications, 2014

    The method of diagnosing machine systems by measuring the accuracy of manufactured parts

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    © Published under licence by IOP Publishing Ltd. The main provisions of the technique allowing to create a diagnostic complex of the technical state of the machine system, which is informative at the same time of several diagnostic complexes - geometrical accuracy, strain gauge, technological accuracy, the influence of technological heredity - are revealed

    Development of the design of a laboratory vibro-grinding machine for preparing samples for metallographic research

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    © Published under licence by IOP Publishing Ltd. The article presents the results of testing a prototype vibro-grinding laboratory machine for making samples for metallographic examination. The effectiveness of the method and its suitability for the preparation of thin sections during laboratory studies in the discipline "Material Science" have been established

    The limits of normal approximation for adult height

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    Adult height inspired the first biometrical and quantitative genetic studies and is a test-case trait for understanding heritability. The studies of height led to formulation of the classical polygenic model, that has a profound influence on the way we view and analyse complex traits. An essential part of the classical model is an assumption of additivity of effects and normality of the distribution of the residuals. However, it may be expected that the normal approximation will become insufficient in bigger studies. Here, we demonstrate that when the height of hundreds of thousands of individuals is analysed, the model complexity needs to be increased to include non-additive interactions between sex, environment and genes. Alternatively, the use of log-normal approximation allowed us to still use the additive effects model. These findings are important for future genetic and methodologic studies that make use of adult height as an exemplar trait

    Cliques and duplication-divergence network growth

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    A population of complete subgraphs or cliques in a network evolving via duplication-divergence is considered. We find that a number of cliques of each size scales linearly with the size of the network. We also derive a clique population distribution that is in perfect agreement with both the simulation results and the clique statistic of the protein-protein binding network of the fruit fly. In addition, we show that such features as fat-tail degree distribution, various rates of average degree growth and non-averaging, revealed recently for only the particular case of a completely asymmetric divergence, are present in a general case of arbitrary divergence.Comment: 7 pages, 6 figure

    Recombination dramatically speeds up evolution of finite populations

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    We study the role of recombination, as practiced by genetically-competent bacteria, in speeding up Darwinian evolution. This is done by adding a new process to a previously-studied Markov model of evolution on a smooth fitness landscape; this new process allows alleles to be exchanged with those in the surrounding medium. Our results, both numerical and analytic, indicate that for a wide range of intermediate population sizes, recombination dramatically speeds up the evolutionary advance

    Data-adaptive harmonic spectra and multilayer Stuart-Landau models

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    Harmonic decompositions of multivariate time series are considered for which we adopt an integral operator approach with periodic semigroup kernels. Spectral decomposition theorems are derived that cover the important cases of two-time statistics drawn from a mixing invariant measure. The corresponding eigenvalues can be grouped per Fourier frequency, and are actually given, at each frequency, as the singular values of a cross-spectral matrix depending on the data. These eigenvalues obey furthermore a variational principle that allows us to define naturally a multidimensional power spectrum. The eigenmodes, as far as they are concerned, exhibit a data-adaptive character manifested in their phase which allows us in turn to define a multidimensional phase spectrum. The resulting data-adaptive harmonic (DAH) modes allow for reducing the data-driven modeling effort to elemental models stacked per frequency, only coupled at different frequencies by the same noise realization. In particular, the DAH decomposition extracts time-dependent coefficients stacked by Fourier frequency which can be efficiently modeled---provided the decay of temporal correlations is sufficiently well-resolved---within a class of multilayer stochastic models (MSMs) tailored here on stochastic Stuart-Landau oscillators. Applications to the Lorenz 96 model and to a stochastic heat equation driven by a space-time white noise, are considered. In both cases, the DAH decomposition allows for an extraction of spatio-temporal modes revealing key features of the dynamics in the embedded phase space. The multilayer Stuart-Landau models (MSLMs) are shown to successfully model the typical patterns of the corresponding time-evolving fields, as well as their statistics of occurrence.Comment: 26 pages, double columns; 15 figure
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