4,110 research outputs found

    Properties of discrete breathers in graphane from ab initio simulations

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    A density functional theory (DFT) study of the discrete breathers (DBs) in graphane (fully hydrogenated graphene) was performed. To the best of our knowledge, this is the first demonstration of the existence of DBs in a crystalline body from the first-principle simulations. It is found that the DB is a robust, highly localized vibrational mode with one hydrogen atom oscillating with a large amplitude along the direction normal to the graphane plane with all neighboring atoms having much smaller vibration amplitudes. DB frequency decreases with increase in its amplitude, and it can take any value within the phonon gap and can even enter the low-frequency phonon band. The concept of DB is then used to propose an explanation to the recent experimental results on the nontrivial kinetics of graphane dehydrogenation at elevated temperatures.Comment: 20.07.14 Submitted to PhysRev

    Oncology disease in patients with acute myocardial infarction with nonobstructive coronary atherosclerosis

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    The aim of this study was to evaluate the cancer incidence among patients with myocardia

    Radio emission from satellite-Jupiter interactions (especially Ganymede)

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    Analyzing a database of 26 years of observations of Jupiter from the Nan\c{c}ay Decameter Array, we study the occurrence of Io-independent emissions as a function of the orbital phase of the other Galilean satellites and Amalthea. We identify unambiguously the emissions induced by Ganymede and characterize their intervals of occurrence in CML and Ganymede phase and longitude. We also find hints of emissions induced by Europa and, surprisingly, by Amalthea. The signature of Callisto-induced emissions is more tenuous.Comment: 14 pages, 7 figures, in "Planetary Radio Emissions VIII", G. Fischer, G. Mann, M. Panchenko and P. Zarka eds., Austrian Acad. Sci. Press, Vienna, in press, 201

    Intraobserver reproducibility of parameters of standard and 2D speckle tracking echocardiography, dynamics of global longitudinal strain I in patients with acute primary anterior STEMI

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    The aim of this study was to assess the intraobserver reproducibility of parameters of standard and 2 dimensional speckle tracking echocardiography, dynamics of global longitudinal strain in patients with acute primary anterior STEMI. The study included 24 patients, mean age 58.46±10.2. Echocardiography with 2D speckle tracking imaging was performed on the 1st (T1), 7th (T2), 14th days (T3) after STEMI («Vivid E9»). Analysis of echocardiographic images was performed offline at the different periods by the two independent observers (EchoPac) – experienced and inexperienced. In order to assess the agreement between standard and 2D speckle tracking echocardiography, a correlation analysis (Pearson correlation, Spearman’s rank correlation coefficient) and Bland-Altman analysis were undertaken. The 23 patients had urgent reperfusion therapy, 6 patients underwent primary PCI, 16 patients – PCI after successful fibrinolysis (68%). GLS and WMSI had the best intraobsever reproducibility. Dynamics of EDV LV, ESV LV, EF LV was without significant differences. Nevertheless, it was found positive dynamic of GLS: – 12.65±3.53 (T1), -13.61±3.81 (T2), –14.27±4.1 (T3), p<0.05. GLS reduced 11.35% (p=0.0048) from T1 to T3. The best intraobserver reproducibility of parameters of 2 D speckle-tracking and standard echocardiography was revealed in GLS and WMSI. The modern management of STEMI patients limits adverse postinfarction remodeling and preserves of global left ventricular contractility detected by the EF LV. However, GLS had the positive dynamics and improved to the 14th day

    Stability of Nonlinear Normal Modes in the FPU-β\beta Chain in the Thermodynamic Limit

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    All possible symmetry-determined nonlinear normal modes (also called by simple periodic orbits, one-mode solutions etc.) in both hard and soft Fermi-Pasta-Ulam-β\beta chains are discussed. A general method for studying their stability in the thermodynamic limit, as well as its application for each of the above nonlinear normal modes are presented

    The "Horizon-T" Experiment: Extensive Air Showers Detection

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    Horizon-T is an innovative detector system constructed to study Extensive Air Showers (EAS) in the energy range above 10^16 eV coming from a wide range of zenith angles (0 - 85 degrees). The system is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. It consists of eight charged particle detection points separated by the distance up to one kilometer as well as optical detector subsystem to view the Vavilov-Cerenkov light from the EAS. The time resolution of charged particles and Vavilov-Cerenkov light photons passage of the detector system is a few ns. This level of resolution allows conducting research of atmospheric development of individual EAS.Comment: Initial technical note for Horizon-T experiment, updated with recent detector upgrades, 11/2016. Updated 12/2017 with minor edits. Large upgrade will be in another articl

    Oxidation of n-С5-С8 hydrocarbons and cyclohexane in a reactor with barrier discharge. P. 2. Simulating cyclohexane oxidation reaction

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    Numerical model of hydrocarbon oxidation kinetics in a reactor with barrier discharge has been proposed by the example of cyclohexane oxidation reaction. The results of calculations with the use of barrier discharge surface model showed that electron energy and other discharge characteristics in pure oxygen and in the mixture of oxygen with cyclohexane vapors slightly differ that allowed using a simplified model of homogeneous discharge for simulating cyclohexane oxidation reaction. The results of calculation showed good fit with the experimental dat
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