1,607 research outputs found

    Results and prospects on registration of reflected Cherenkov light of EAS from cosmic particles above 10^{15} eV

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    We give an overview of the SPHERE experiment based on detection of reflected Vavilov-Cherenkov radiation (Cherenkov light) from extensive air showers in the energy region E>10^{15} eV. A brief history of the reflected Cherenkov light technique is given; the observations carried out with the SPHERE-2 detector are summarized; the methods of the experimental datasample analysis are described. The first results on the primary cosmic ray all-nuclei energy spectrum and mass composition are presented. Finally, the prospects of the SPHERE experiment and the reflected Cherenkov light technique are given.Comment: 4 pages, 3 figures, Proc. PANIC-201

    The Lyapunov exponent in the Sinai billiard in the small scatterer limit

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    We show that Lyapunov exponent for the Sinai billiard is λ=2log(R)+C+O(Rlog2R)\lambda = -2\log(R)+C+O(R\log^2 R) with C=14log2+27/(2π2)ζ(3)C=1-4\log 2+27/(2\pi^2)\cdot \zeta(3) where RR is the radius of the circular scatterer. We consider the disk-to-disk-map of the standard configuration where the disks is centered inside a unit square.Comment: 15 pages LaTeX, 3 (useful) figures available from the autho

    Deterministic diffusion in flower shape billiards

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    We propose a flower shape billiard in order to study the irregular parameter dependence of chaotic normal diffusion. Our model is an open system consisting of periodically distributed obstacles of flower shape, and it is strongly chaotic for almost all parameter values. We compute the parameter dependent diffusion coefficient of this model from computer simulations and analyze its functional form by different schemes all generalizing the simple random walk approximation of Machta and Zwanzig. The improved methods we use are based either on heuristic higher-order corrections to the simple random walk model, on lattice gas simulation methods, or they start from a suitable Green-Kubo formula for diffusion. We show that dynamical correlations, or memory effects, are of crucial importance to reproduce the precise parameter dependence of the diffusion coefficent.Comment: 8 pages (revtex) with 9 figures (encapsulated postscript

    Replacement of the aortic valve, ascending aorta and arch in a patient with dextrocardia in the context of situs inversus totalis: a case report

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    The article discusses a rare case of successful replacement of the aortic valve, ascending  aorta and arch in a patient with dextrocardia  in the context  of situs inversus totalis. Situs inversus is a rare variant of normal anatomy  in which the major visceral organs are mirrored from their normal positions

    Comparison of open femoral exposure and percutaneous access in endovascular reconstruction of the thoracic aorta: a two-center retrospective study

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    Aim. To analyze the efficacy and safety of the percutaneous transfemoral puncture technique for TEVAR (thoracis endovascular aortic repair).Material and methods. The retrospective study included 89 patients with aortic pathologies, for whom endovascular repair was performed: 51 patients (57%) with aortic dissection (type I DeBakey — 30 cases (58,8%) and type III — 21 (41,2%)), 38 (43%) patients with aortic aneurism. 82% of patients were male, the median age was 57 years (minimum age 17 years, maximum age 75 years). All patients were divided into two groups: in the first group (48 patients) endovascular aortic repair was performed under endotracheal anesthesia with open femoral exposure of the common femoral artery (CFA), in the second group (41 patients) — by percutaneous puncture method under local anesthesia. Technical and clinical aspects of procedures were analyzed.Results. Technical success of endovascular repair was achieved in 100% cases in both groups. The duration of the operation in the group with percutaneous access was statically significantly shorter (120 (94-150) minutes vs 87(60-120) minutes, p=0,001). Also, the time spent by patients in the intensive care unit and the period of hospitalization (18 (14-22) hours versus 1 (0-3) hours, p=0,001; 5 (4-6) days versus 4 (3-5) days, p=0,03) was shorter. In the open access group 2 (4,2%) patients developed access-related complications - acute thrombosis of the common femoral artery and hematoma of the postoperative wound, which required additional surgical aid - thrombectomy from the CFA, the second patient had evacuation of the hematoma of the postoperative wound. Cite-related complications in the second group were not observed. No major complications including neurological deficits and hospital mortality were observed in both groups.Conclusions. Thoracic endovascular aortic repair (TEVAR) using percutaneous access under local anesthesia in stable patients has proven to be safe and effective. The operation time is significantly reduced and this approach in most cases eliminates the need for the patient to stay in the intensive care unit in the early postoperative period. Possibility of early mobilization of the patient appears with reducing of the duration of hospitalization
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