867 research outputs found

    Exploring the cosmic microwave background as a composition of signals with Kolmogorov analysis

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    The problem of separation of different signals in the Cosmic Microwave Background (CMB) radiation using the difference in their statistics is analyzed. Considering samples of sequences which model the CMB as a superposition of signals, we show how the Kolmogorov stochasticity parameter acts as a relevant descriptor, either qualitatively or quantitatively, to distinguish the statistical properties of the cosmological and secondary signals.Comment: Mod. Phys. Lett. (in press), 13 pages, 7 figure

    Probing the statistic in the cosmic microwave background

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    Kolmogorov's statistic is used for the analysis of properties of perturbations in the Cosmic Microwave Background signal. We obtain the maps of the Kolmogorov stochasticity parameter for W and V band temperature data of WMAP which are differently affected by the Galactic disk radiation and then we model datasets with various statistic of perturbations. The analysis shows that the Kolmogorov's parameter can be an efficient tool for the separation of Cosmic Microwave Background from the contaminating radiations due to their different statistical properties.Comment: 6 pages, 4 figure

    Study of the performance and capability of the new ultra-fast 2 GSample/s FADC data acquisition system of the MAGIC telescope

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    In February 2007 the MAGIC Air Cherenkov Telescope for gamma-ray astronomy was fully upgraded with an ultra fast 2 GSamples/s digitization system. Since the Cherenkov light flashes are very short, a fast readout can minimize the influence of the background from the light of the night sky. Also, the time structure of the event is an additional parameter to reduce the background from unwanted hadronic showers. An overview of the performance of the new system and its impact on the sensitivity of the MAGIC instrument will be presented.Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of the MAGIC Collaboratio

    GRB 050713A: High Energy Observations of the GRB Prompt and Afterglow Emission

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    Swift discovered GRB 050713A and slewed promptly to begin observing with its narrow field instruments 72.6 seconds after the burst onset, while the prompt gamma-ray emission was still detectable in the BAT. Simultaneous emission from two flares is detected in the BAT and XRT. This burst marks just the second time that the BAT and XRT have simultaneously detected emission from a burst and the first time that both instruments have produced a well sampled, simultaneous dataset covering multiple X-ray flares. The temporal rise and decay parameters of the flares are consistent with the internal shock mechanism. In addition to the Swift coverage of GRB 050713A, we report on the Konus-Wind (K-W) detection of the prompt emission in the energy range 18-1150 keV, an upper limiting GeV measurement of the prompt emission made by the MAGIC imaging atmospheric Cherenkov telescope and XMM-Newton observations of the afterglow. Simultaneous observation between Swift XRT and XMM-Newton produce consistent results, showing a break in the lightcurve at T+~15ks. Together, these four observatories provide unusually broad spectral coverage of the prompt emission and detailed X-ray follow-up of the afterglow for two weeks after the burst trigger. Simultaneous spectral fits of K-W with BAT and BAT with XRT data indicate that an absorbed broken powerlaw is often a better fit to GRB flares than a simple absorbed powerlaw. These spectral results together with the rapid temporal rise and decay of the flares suggest that flares are produced in internal shocks due to late time central engine activity.Comment: 22 pages, 6 tables, 10 figures; Submitted to the Astrophysical Journa

    Echocardiographic screening of children and teenagers during routine physical examination

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    Objective: to study the frequency of occurrence of diseases of the cardiovascular system in the course of routine physical examination of the child population, with the purpose of early recognition of various pathological conditions, including structural anomalies of the heart and large vessels.Material and methods: total examined 260 childrens aged 6 to 14 years, 118 girls (45.3 %) and 142 boys (54.6 %). Screening survey was performed in the parasternal, apical and subcostal positions. Time to research occupied from 7 to 20 minutes.Results: out of 260 children who passed clinical examination a structural anomalies of the heart was detected in 56 patients (21,5 % of all researches).Conclusions: the clinical examination of children population has a colossal medical and social important not only in Russia, but all over the world. Echocardiographic screening of children of preschool age is necessary for timely detection of cardiovascular pathology, especially occurring asymptomatically

    Neuroprotective and cerebrovascular effects of endogenous N-Arachidonoyl-GABA and its putative Cox-2 metabolite - GABA conjugate with Prostaglandin E2

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    The aim of the study was to compare the neuroprotective and cerebrovascular effects of bioactive, endogenous lipid-N-arachidonoyl-GABA (AA-GABA) and GABA conjugate with prostaglandin E2 (PGE2-GABA) by evaluation of a morphological state of rat brain tissue and lipofuscin levels under the condition of permanent focal brain ischemia, as well as cerebral circulation under the condition of global transient ischemi

    Migraine pharmacology and brain ischemia

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    The aim of this review article was to analyze in details the mechanism of drugs’ effects in the treatment and prevention of a migraine attack, as well as to discuss the hypotheses of migraine pathogenesi

    New antiarrhythmic agent to stabilize functional activity of rat heart sinus node cardiomyocytes

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    The aim of this study was to explore the antiarrhythmic activity of the new antiarrhythmic drug, succinic acid ester of 5-hydroxyadamantane-2-one (ADK-1110) and its effect on the functional activity of rat heart sinus nod

    Enhancing optimization capabilities using the AGILE collaborative MDO framework with application to wing and nacelle design

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    This paper presents methodological investigations performed in research activities in the field of Multi-disciplinary Design and Optimization (MDO) for overall aircraft design in the EU funded research project AGILE (2015–2018). In the AGILE project a team of 19 industrial, research and academic partners from Europe, Canada and Russia are working together to develop the next generation of MDO environment that targets significant reductions in aircraft development costs and time to market, leading to cheaper and greener aircraft. The paper introduces the AGILE project structure and describes the achievements of the 1st year that led to a reference distributed MDO system. A focus is then made on different novel optimization techniques studied during the 2nd year, all aiming at easing the optimization of complex workflows that are characterized by a high number of discipline interdependencies and a large number of design variables in the context of multi-level processes and multi-partner collaborative engineering projects. Three optimization strategies are introduced and validated for a conventional aircraft. First, a multi-objective technique based on Nash Games and Genetic Algorithm is used on a wing design problem. Then a zoom is made on the nacelle design where a surrogate-based optimizer is used to solve a mono-objective problem. Finally a robust approach is adopted to study the effects of uncertainty in parameters on the nacelle design process. These new capabilities have been integrated in the AGILE collaborative framework that in the future will be used to study and optimize novel unconventional aircraft configurations

    The optical counterpart to gamma-ray burst GRB970228 observed using the Hubble Space Telescope

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    Although more than 2,000 astronomical gamma-ray bursts (GRBs) have been detected, and numerous models proposed to explain their occurrence, they have remained enigmatic owing to the lack of an obvious counterpart at other wavelengths. The recent ground-based detection of a transient source in the vicinity of GRB 970228 may therefore have provided a breakthrough. The optical counterpart appears to be embedded in an extended source which, if a galaxy as has been suggested, would lend weight to those models that place GRBs at cosmological distances. Here we report the observations using the Hubble Space Telescope of the transient counterpart and extended source 26 and 39 days after the initial gamma-ray outburst. We find that the counterpart has faded since the initial detection (and continues to fade), but the extended source exhibits no significant change in brightness between the two dates of observations reported here. The size and apparent constancy between the two epochs of HST observations imply that it is extragalactic, but its faintness makes a definitive statement about its nature difficult. Nevertheless, the decay profile of the transient source is consistent with a popular impulsive-fireball model, which assumes a merger between two neutron stars in a distant galaxy.Comment: 11 pages + 2 figures. To appear in Nature (29 May 1997 issue
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