377 research outputs found

    Self-tuning of the P-vortices

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    We observe that on the currently available lattices the non-Abelian action associated with the P-vortices is ultraviolet divergent. On the other hand, the total area of the vortices scales in physical units. Since both the ultraviolet and infrared scales are manifested and there is no parameter to tune, the observed phenomenon can be called self tuning.Comment: Lattice2003(topology

    Unified Characterization of Crack Growth Parameters based on Plastic Stress Intensity Factor

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    AbstractThe aim of this work is to study and represent the combined in-plane and out-of-plane constraint effect on the material fracture resistance characteristics under static and fatigue loading. Subjects for numerical and experimental studies are three-point bending and compact specimens under static loading as well as cruciform specimens under cyclic biaxial and mixed mode loading. For the static tests experimental specimen geometries considered (SENB and CS), the elastic constraint parameters and the parameter governing of the plastic stress field In distributions are obtained as a function of both the specimen thickness, the dimensionless crack length and crack length. For the fatigue tests specimen configurations (CCS) the T-stress and the numerical constant In are calculated with the variation of biaxial stress ratio and full range mode mixity. A method is also suggested for calculating the plastic stress intensity factor for mixed-mode I/II loading based on the T-stress and power law solutions. It is found that the plastic stress intensity factor accounting for the in-plane and out-of-plane constraint effect can be applied to characterize the fracture toughness and the multiaxial crack growth rate for a variety specimen geometries

    Gauge-ready formulation of the cosmological kinetic theory in generalized gravity theories

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    We present cosmological perturbations of kinetic components based on relativistic Boltzmann equations in the context of generalized gravity theories. Our general theory considers an arbitrary number of scalar fields generally coupled with the gravity, an arbitrary number of mutually interacting hydrodynamic fluids, and components described by the relativistic Boltzmann equations like massive/massless collisionless particles and the photon with the accompanying polarizations. We also include direct interactions among fluids and fields. The background FLRW model includes the general spatial curvature and the cosmological constant. We consider three different types of perturbations, and all the scalar-type perturbation equations are arranged in a gauge-ready form so that one can implement easily the convenient gauge conditions depending on the situation. In the numerical calculation of the Boltzmann equations we have implemented four different gauge conditions in a gauge-ready manner where two of them are new. By comparing solutions solved separately in different gauge conditions we can naturally check the numerical accuracy.Comment: 26 pages, 9 figures, revised thoroughly, to appear in Phys. Rev.

    Multimodal evoked potential in monitoring activity relapsing and remitting multiple sclerosis

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    The aim of the study was to examine multimodal evoked potential in patients with or without relapse multiple sclerosis during 12 month. Material and Methods. The study included 32 patients with established diagnosis of clinically significant multiple sclerosis, a relapsing-remitting course. The EDSS score was evaluated. All patients underwent a study of multimodal evoked potential. All examined patients were divided into 2 groups depending on the relapse multiple sclerosis by the end of the year. Results. Multimodal evoked potentials show ambiguous data on the activity of multiple sclerosis. The greatest correlation with subsequent activity of multiple sclerosis is shown by stem evoked potentials. Conclusion. This study is the initial stage in the search for a tool for predicting the course of the disease in patients with multiple sclerosis. An increase in the group of subjects and inclusion in the analysis of structural changes in the central nervous system according to magnetic resonance imaging probably will increase the information content of predictions

    The analysis of the clinical and tool parameters characterizing a cardiomyopathyat various forms of the progressing muscular dystrophies

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    Purpose: studying of clinical and tool characteristics of cardiomyopathies at various forms of the progressing muscular dystrophies. Material and methods. There had been 103 patients with hereditary forms of the progressing muscular dystrophies examined, among which 35 persons were with Duchenne muscular dystrophy, 28 with an atrophic myo-tonia, and 40 with a limb girdle dystrophy is conducted. Assessment of clinical and tool features of cardiomyopathies at these types of the hereditary progressing muscular dystrophies had been carried out. Results. In the group of patients with diffusion damage of a myocardium in the form of dystrophic violations had been revealed. Existence of a negative tooth of T in some assignments and lengthenings of an interval of QT is noted. With a dystrophic myotonia violation of a warm rhythm occurred at patients by 87 times more often than in the group of comparison. Violation of a rhythm of heart in group of patients with a limb girdle dystrophy came to light 91 times more often in reference to the group of comparison. Conclusion. Violations in a cardiovascular system at Duchenne muscular dystrophy are preferentially diffusion changes in a myocardium. At a dystrophic myotonia and a limb girdle dystrophy cardial violations concern mainly excitability and the conductivity of heart which are the main reason of developing of this disease at these patients.</p

    Dynamics of acetylcholine receptors antibody titer in myasthenia gravis

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    The aim was to examine the longitudinal association between myasthenia gravis clinical severity and concentration of acetylcholine receptor (AChR) antibodies to evaluate if AChR-antibody variations correlate to disease severity. Material and Methods. Antibodies were determined by enzyme immunoassay. The International Clinical Classification (MGFA) was used to grade the severity of the disease. The level of antibodies was compared with the severity of the condition and the form of the disease at the stage of diagnosis in 65 patients, as well as in repeated studies in 26 patients. Results. The titer of AChR-antibodies did not correlate with the severity of the condition, however, a direct relationship between the change in the level of acetylcholine receptor antibodies and the change in the clinical state during the course of the disease was obtained. Conclusion. Repeated AChR-antibody measurements will help to predict the clinical state of the patient and can be used to correct immunosuppressive therapy.</p

    Energy transmission in the forbidden bandgap of a nonlinear chain

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    A nonlinear chain driven by one end may propagate energy in the forbidden band gap by means of nonlinear modes. For harmonic driving at a given frequency, the process ocurs at a threshold amplitude by sudden large energy flow, that we call nonlinear supratransmission. The bifurcation of energy transmission is demonstrated numerically and experimentally on the chain of coupled pendula (sine-Gordon and nonlinear Klein-Gordon equations) and sustained by an extremely simple theory.Comment: LaTex file, 6 figures, published in Phys Rev Lett 89 (2002) 13410

    Interplay of Monopoles and P-Vortices

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    We show that P-Vortices in the confinement phase of SU(2) lattice gauge theory form one large percolating (infrared) cluster and a number of small (ultraviolet) clusters. We discuss the interrelation of clusters of monopoles in the maximal Abelian projection with clusters of P-vortices. To extract P-vortices we use both direct and indirect central projections and find qualitatively similar results.Comment: 3 pages, 4 figures; talk given at Lattice 2003 (Tsukuba, Japan

    Confinement and soliton solutions in the SL(3) Toda model coupled to matter fields

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    We consider an integrable conformally invariant two dimensional model associated to the affine Kac-Moody algebra SL(3). It possesses four scalar fields and six Dirac spinors. The theory does not possesses a local Lagrangian since the spinor equations of motion present interaction terms which are bilinear in the spinors. There exists a submodel presenting an equivalence between a U(1) vector current and a topological current, which leads to a confinement of the spinors inside the solitons. We calculate the one-soliton and two-soliton solutions using a procedure which is a hybrid of the dressing and Hirota methods. The soliton masses and time delays due to the soliton interactions are also calculated. We give a computer program to calculate the soliton solutions.Comment: plain LaTeX, 37 page

    Fine tuned vortices in lattice SU(2) gluodynamics

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    We report measurements of the action associated with center vortices in SU(2) pure lattice gauge theory. In the lattice units the excess of the action on the plaquettes belonging to the vortex is approximately a constant, independent on the lattice spacing 'a'. Therefore the action of the center vortex is of order 'A/a^2', where 'A' is its area. Since the area 'A' is known to scale in the physical units, the measurements imply that the suppression due to the surface action is balanced, or fine tuned to the entropy factor which is to be an exponential of 'A/a^2'.Comment: Version accepted for publication in PLB, stylistic change
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