11,125 research outputs found

    Effective potential for Polyakov loops from a center symmetric effective theory in three dimensions

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    We present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of a gauge invariant kinetic term, spatial gauge fields and a potential for the Wilson line which includes a "fuzzy" bag term to generate non-perturbative fluctuations. The effective potential for the Polyakov loop is extracted from the simulations including all modes of the loop as well as for cooled configuration where the hard modes have been averaged out. The former is found to exhibit a non-analytic contribution while the latter can be described by a mean-field like ansatz with quadratic and quartic terms, plus a Vandermonde potential which depends upon the location within the phase diagram.Comment: 10 pages, 22 figures, v2: published version (minor clarifications, update of reference list

    Economic communication model set

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    This paper details findings from the research work targeted at economic communications investigation with agent-based models usage. The agent-based model set was engineered to simulate economic communications. Money in the form of internal and external currencies was introduced into the models to support exchanges in communications. Every model, being based on the general concept, has its own peculiarities in algorithm and input data set since it was engineered to solve the specific problem. Several and different origin data sets were used in experiments: theoretic sets were estimated on the basis of static Leontief's equilibrium equation and the real set was constructed on the basis of statistical data. While simulation experiments, communication process was observed in dynamics, and system macroparameters were estimated. This research approved that combination of an agent-based and mathematical model can cause a synergetic effect. © 2017 Author(s)

    Thermodynamics of two lattice ice models in three dimensions

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    In a recent paper we introduced two Potts-like models in three dimensions, which share the following properties: (A) One of the ice rules is always fulfilled (in particular also at infinite temperature). (B) Both ice rules hold for groundstate configurations. This allowed for an efficient calculation of the residual entropy of ice I (ordinary ice) by means of multicanonical simulations. Here we present the thermodynamics of these models. Despite their similarities with Potts models, no sign of a disorder-order phase transition is found.Comment: 5 pages, 7 figure

    Particle Dispersion on Rapidly Folding Random Hetero-Polymers

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    We investigate the dynamics of a particle moving randomly along a disordered hetero-polymer subjected to rapid conformational changes which induce superdiffusive motion in chemical coordinates. We study the antagonistic interplay between the enhanced diffusion and the quenched disorder. The dispersion speed exhibits universal behavior independent of the folding statistics. On the other hand it is strongly affected by the structure of the disordered potential. The results may serve as a reference point for a number of translocation phenomena observed in biological cells, such as protein dynamics on DNA strands.Comment: 4 pages, 4 figure

    Tin dioxide sol-gel derived thin films deposited on porous silicon

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    Undoped and Sb-doped SnO2 sol¿gel derived thin films have been prepared for the first time from tin (IV) ethoxide precursor and SbCl3 in order to be utilised for gas sensing applications where porous silicon is used as a substrate. Transparent, crack-free and adherent layers were obtained on different types of substrates (Si, SiO2/Si). The evolution of the Sn¿O chemical bonds in the SnO2 during film consolidation treatments was monitored by infrared spectroscopy. By energy dispersive X-ray spectroscopy performed on the cross section of the porosified silicon coupled with transmission electron microscopy, the penetration of the SnO2 sol¿gel derived films in the nanometric pores of the porous silicon has been experimentally proved

    Forehead Skin Blood Flow in Normal Neonates during Active and Quiet Sleep, Measured with a Diode Laser Doppler Instrument

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    Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter without light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep states could be distinguished in 17 recordings. The mean skin blood flow values during active sleep were significantly higher (p<0.01) than those during quiet sleep, the mean increase being 28.1%. The variability of the flow signal, expressed as the coefficient of variation, changed significantly from 23.1% during active sleep to 18.2% during quiet sleep

    Loop structure of the lowest Bloch band for a Bose-Einstein condensate

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    We investigate analytically and numerically Bloch waves for a Bose--Einstein condensate in a sinusoidal external potential. At low densities the dependence of the energy on the quasimomentum is similar to that for a single particle, but at densities greater than a critical one the lowest band becomes triple-valued near the boundary of the first Brillouin zone and develops the structure characteristic of the swallow-tail catastrophe. We comment on the experimental consequences of this behavior.Comment: 4 pages, 7 figure

    Approximating the Maximum Overlap of Polygons under Translation

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    Let PP and QQ be two simple polygons in the plane of total complexity nn, each of which can be decomposed into at most kk convex parts. We present an (1ε)(1-\varepsilon)-approximation algorithm, for finding the translation of QQ, which maximizes its area of overlap with PP. Our algorithm runs in O(cn)O(c n) time, where cc is a constant that depends only on kk and ε\varepsilon. This suggest that for polygons that are "close" to being convex, the problem can be solved (approximately), in near linear time

    Quantum Chaos in Compact Lattice QED

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    Complete eigenvalue spectra of the staggered Dirac operator in quenched 4d4d compact QED are studied on 83×48^3 \times 4 and 83×68^3 \times 6 lattices. We investigate the behavior of the nearest-neighbor spacing distribution P(s)P(s) as a measure of the fluctuation properties of the eigenvalues in the strong coupling and the Coulomb phase. In both phases we find agreement with the Wigner surmise of the unitary ensemble of random-matrix theory indicating quantum chaos. Combining this with previous results on QCD, we conjecture that quite generally the non-linear couplings of quantum field theories lead to a chaotic behavior of the eigenvalues of the Dirac operator.Comment: 11 pages, 4 figure

    Triadic method for structural balance evaluation

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    За глобальными социальными сетями стали почти не видны малые социальные сети – малые группы. Однако большинство из нас участвуют в производственной деятельности, становясь членом малой производственной группы, учатся, становясь при этом членом другой малой группы – академической группы в университете. Методология анализа социальных сетей (SNA-методология) предлагает методы и информационные инструменты для изучения социальных групп, в том числе и малых. В ходе исследования, проведенного в одном из департаментов Уральского федерального университета, были накоплены данные, позволяющие оценить коммуникационные связи между студентами отдельных академических групп. На основе этих данных был проведен анализ устойчивости одной из академических групп, для которой был сгенерирован триадный вектор. Существующие теории структурного баланса ограничивают вид триад, которые обеспечивают баланс в сети. Проведенный анализ показал, что рассмотренная академическая группа достаточно сбалансирована по структуре и отличается повышенной степенью транзитивности.In comparison to global social networks small networks are paid less research attention. But most of us are involved in manufacturing activity,thus becoming a member of a small manufacturing group or study at the University entering an academic group.SNA-methodolgy (SNA – Social Network Analysis) proposes special methods and information instruments for social groups including small groups study.In the ranks of the research work held in the Ural Federal University department data about communications between students from different academic groups was collected. This data becomes the base for these communications evaluating.Using this data for triadic vector estimation the analysis of the appropriate academic group sustainability was conducted. Comprehensive theories of sustainability restrict the set of possible triad types which support structural balance in a network.The analysis showed that the group under discussion may be considered as a sustainable one and it has the increased level of transitivity as compared to the estimated value
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