150 research outputs found

    The Width and Integer Optimization on Simplices With Bounded Minors of the Constraint Matrices

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    In this paper, we will show that the width of simplices defined by systems of linear inequalities can be computed in polynomial time if some minors of their constraint matrices are bounded. Additionally, we present some quasi-polynomial-time and polynomial-time algorithms to solve the integer linear optimization problem defined on simplices minus all their integer vertices assuming that some minors of the constraint matrices of the simplices are bounded.Comment: 12 page

    Optimization of the Algorithm for Choosing the Surgical Treatment of Anterior Recurrent Instability of the Shoulder Joint

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    Introduction. Chronic recurrent instability of the shoulder joint is a frequent outcome of conservative treatment oftraumatic dislocation of the shoulder (2.8–30 % of cases). Preoperative examination largely determines the outcome of surgical treatment of this pathology.The aim of the study was to provide a clinical assessment of the developed algorithm for the surgical treatment of patients with recurrent anterior shoulder joint instability. Materials and methods. The results of treatment of 98 patients with recurrent anterior shoulder joint instability were studied. Preoperative examination included clinical tests, MRI or CT with calculation of bone loss. Fifty-six patients (57.1 %) underwent Bankart operation, 14 patients (14.3 %) – Latarjet operation. Twenty-three patients (23.5 %) underwent Bankart + Remplissage surgery, and 5 (5.1 %) – Latarjet + remplissage. The result was assessed on the ROWE scale.Results. Bone defects significant in the formation of instability (“glenoid off track”) were found in 19.4 % of patients, and “glenoid on track” – in 80.6 %. According to the proposed algorithm for treating patients with anterior recurrent instability of the shoulder joint, the “glenoid off track” state was an indication for Latarjet surgery. When “glenoid on track” was used, indications for Bankart operation were displayed. The remplissage procedure was indicated in case of the presence of a Hill-Sachs grade 3 defect or the presence of hyperelasticity of the tissues of the shoulder joint. The mean ROWE score for the entire group of patients before surgery was 41.5 ± 12.8 points, and 15 months after sur gery – 94.9 ± 3.4 points. Two recurrent dislocations were revealed, one of which was associated with repeated trauma, and the other – with an incorrect choice of stabilization technique. One complication (axillary nerve neuropathy) was observed, which was arrested conservatively.Conclusions. The proposed algorithm allowed us to obtain positive results in 97.9 % of cases

    Chaos, Fractals and Inflation

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    In order to draw out the essential behavior of the universe, investigations of early universe cosmology often reduce the complex system to a simple integrable system. Inflationary models are of this kind as they focus on simple scalar field scenarios with correspondingly simple dynamics. However, we can be assured that the universe is crowded with many interacting fields of which the inflaton is but one. As we describe, the nonlinear nature of these interactions can result in a complex, chaotic evolution of the universe. Here we illustrate how chaotic effects can arise even in basic models such as homogeneous, isotropic universes with two scalar fields. We find inflating universes which act as attractors in the space of initial conditions. These universes display chaotic transients in their early evolution. The chaotic character is reflected by the fractal border to the basin of attraction. The broader implications are likely to be felt in the process of reheating as well as in the nature of the cosmic background radiation.Comment: 16 pages, RevTeX. See published version for fig

    Fractal Spin Glass Properties of Low Energy Configurations in the Frenkel-Kontorova chain

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    We study numerically and analytically the classical one-dimensional Frenkel-Kontorova chain in the regime of pinned phase characterized by phonon gap. Our results show the existence of exponentially many static equilibrium configurations which are exponentially close to the energy of the ground state. The energies of these configurations form a fractal quasi-degenerate band structure which is described on the basis of elementary excitations. Contrary to the ground state, the configurations inside these bands are disordered.Comment: revtex, 9 pages, 9 figure

    Collimation of a Circulating Beam in the U_70 Synchrotron by Use of Reflections in Axially - Oriented Crystals

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    The possibilities of the extraction and collimation of a circulating beam by a new method due to the reflection of particles in crystals with axial orientation were experimentally investigated in the Fall-2010 run at the U_70 synchrotron. Such crystals have positive features, because the axial potential is five times larger than the planar potential. It has been shown that the collimation efficiency can reach 90% due to axial effects in the crystal. Losses of the circulating beam on a collimator have been reduced by several times; this makes it possible to suppress the muon jet near the steel collimator of the circulating beam.Comment: 6 pages, 7 figure

    Fluorescence Dequenching Makes Haem-Free Soluble Guanylate Cyclase Detectable in Living Cells

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    In cardiovascular disease, the protective NO/sGC/cGMP signalling-pathway is impaired due to a decreased pool of NO-sensitive haem-containing sGC accompanied by a reciprocal increase in NO-insensitive haem-free sGC. However, no direct method to detect cellular haem-free sGC other than its activation by the new therapeutic class of haem mimetics, such as BAY 58-2667, is available. Here we show that fluorescence dequenching, based on the interaction of the optical active prosthetic haem group and the attached biarsenical fluorophor FlAsH can be used to detect changes in cellular sGC haem status. The partly overlap of the emission spectrum of haem and FlAsH allows energy transfer from the fluorophore to the haem which reduces the intensity of FlAsH fluorescence. Loss of the prosthetic group, e.g. by oxidative stress or by replacement with the haem mimetic BAY 58-2667, prevented the energy transfer resulting in increased fluorescence. Haem loss was corroborated by an observed decrease in NO-induced sGC activity, reduced sGC protein levels, and an increased effect of BAY 58-2667. The use of a haem-free sGC mutant and a biarsenical dye that was not quenched by haem as controls further validated that the increase in fluorescence was due to the loss of the prosthetic haem group. The present approach is based on the cellular expression of an engineered sGC variant limiting is applicability to recombinant expression systems. Nevertheless, it allows to monitor sGC's redox regulation in living cells and future enhancements might be able to extend this approach to in vivo conditions

    Endothelial dysfunction and glycocalyx shedding in heart failure:insights from patients receiving cardiac resynchronisation therapy

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    To determine (a) whether chronic heart failure with reduced ejection fraction (HFrEF) is associated with increased glycocalyx shedding; (b) whether glycocalyx shedding in HFrEF with left ventricular dyssynchrony is related to inflammation, endothelial dysfunction and/or redox stress and is ameliorated by cardiac resynchronisation therapy. Glycocalyx shedding has been reported to be increased in heart failure and is a marker of increased mortality. Its role in dyssynchronous systolic heart failure and the effects of cardiac resynchronisation therapy (CRT) are largely unknown. Twenty-six patients with dyssynchronous HFrEF were evaluated before and 6 months after CRT insertion. Echocardiographic septal to posterior wall delay (SPWD) assessed intra-ventricular mechanical dyssynchrony, and quality of life, integrity of nitric oxide (NO) signalling, inflammatory and redox-related biomarkers were measured. Glycocalyx shedding was quantitated via plasma levels of the glycocalyx component, syndecan-1. Syndecan-1 levels pre-CRT were inversely correlated with LVEF (r = - 0.45, p = 0.02) and directly with SPWD (r = 0.44, p = 0.02), QOL (r = 0.39, p = 0.04), plasma NT-proBNP (r = 0.43, p = 0.02), and the inflammatory marker, symmetric dimethylarginine (SDMA) (r = 0.54, p = 0.003). On multivariate analysis, syndecan-1 levels were predicted by SPWD and SDMA (β = 0.42, p = 0.009 and β = 0.54, p = 0.001, respectively). No significant correlation was found between syndecan-1 levels and other markers of endothelial dysfunction/inflammatory activation. Following CRT there was no significant change in syndecan-1 levels. In patients with dyssynchronous HFrEF, markers of glycocalyx shedding are associated with the magnitude of mechanical dyssynchrony and elevation of SDMA levels and inversely with LVEF. However, CRT does not reverse this process
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