2,462 research outputs found

    Clustering and Uncertainty in Perfect Chaos Systems

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    The goal of this investigation was to derive strictly new properties of chaotic systems and their mutual relations. The generalized Fokker-Planck equation with a non stationary diffusion has been derived and used for chaos analysis. An anomalous transport turned out to be natural property of this equation. A nonlinear dispersion of the considered motion allowed to find a principal consequence: a chaotic system with uniform dynamic properties tends to unstable clustering. Small fluctuations of particles density increase by time and form attractors and stochastic islands even if the initial transport properties have uniform distribution. It was shown that an instability of phase trajectories leads to the nonlinear dispersion law and consequently to a space instability. A fixed boundary system was considered, using a standard Fokker-Planck equation. We have derived that such a type of dynamic systems has a discrete diffusive and energy spectra. It was shown that phase space diffusion is the only parameter that defines a dynamic accuracy in this case. The uncertainty relations have been obtained for conjugate phase space variables with account of transport properties. Given results can be used in the area of chaotic systems modelling and turbulence investigation.Comment: 9 pages, Journal of Chaos, vol. 2014, open access: http://www.hindawi.com/journals/jcha/2014/292096

    Detection of an intergalactic meteor particle with the 6-m telescope

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    On July 28, 2006 the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences recorded the spectrum of a faint meteor. We confidently identify the lines of FeI and MgI, OI, NI and molecular-nitrogen N_2 bands. The entry velocity of the meteor body into the Earth's atmosphere estimated from radial velocity is equal to 300 km/s. The body was several tens of a millimeter in size, like chondrules in carbon chondrites. The radiant of the meteor trajectory coincides with the sky position of the apex of the motion of the Solar system toward the centroid of the Local Group of galaxies. Observations of faint sporadic meteors with FAVOR TV CCD camera confirmed the radiant at a higher than 96% confidence level. We conclude that this meteor particle is likely to be of extragalactic origin. The following important questions remain open: (1) How metal-rich dust particles came to be in the extragalactic space? (2) Why are the sizes of extragalactic particles larger by two orders of magnitude (and their masses greater by six orders of magnitude) than common interstellar dust grains in our Galaxy? (3) If extragalactic dust surrounds galaxies in the form of dust (or gas-and-dust) aureoles, can such formations now be observed using other observational techniques (IR observations aboard Spitzer satellite, etc.)? (4) If inhomogeneous extragalactic dust medium with the parameters mentioned above actually exists, does it show up in the form of irregularities on the cosmic microwave background (WMAP etc.)?Comment: 9 pages, 6 EPS figure

    ANALYSIS OF RW HANDLING IN FOREIGN COUNTRIES

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    В работе рассмотрен вопрос организации системы обращения с РАО в некоторых зарубежных странах, приведено их сравнение. Кратко описаны проекты по обращению с РАО, приведена их стоимость. Сделан вывод о том, какие действия необходимо предпринять в нашей стране для предотвращения возможных проблем, связанных с РАО.The paper discusses the issue of organizing a radioactive waste (RW) management system in some foreign countries and gives their comparison. RW management projects are briefly described, their cost is given. The conclusion is made about what actions should be taken in our country to prevent possible problems associated with radioactive waste

    Влияние донации оксида азота на выраженность митохондриальной дисфункции почечной ткани при моделировании искусственного кровообращения: экспериментальное исследование

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    АКТУАЛЬНОСТЬ: Одним из наиболее частых осложнений при кардиохирургических операциях с искусственным кровообращением (ИК) является острое почечное повреждение. Ряд исследований показал, что донация экзогенного оксида азота (NO) уменьшает частоту острого почечного повреждения. Однако субклеточные механизмы реализации нефропротективных свойств NO остаются неизвестными. ЦЕЛЬ ИССЛЕДОВАНИЯ: Изучить безопасность технологии плазмохимического синтеза оксида азота и оценить влияние доставки полученного оксида азота на митохондриальное повреждение почечной ткани при моделировании искусственного кровообращения. МАТЕРИАЛЫ И МЕТОДЫ: В эксперимент включили 12 баранов алтайской породы. Животные были разделены на 2 группы: 6 животным моделировали ИК; 6 животным моделировали ИК с доставкой NO. Митохондриальное повреждение оценивалось по кальций-связывающей способности и по трансмембранному потенциалу митохондрий через 1 ч после отлучения от аппарата ИК. Безопасность метода доставки NO по предложенной методике оценивали по концентрации диоксида азота на вдохе, уровню метгемоглобина. Эффективность доставки NO по предложенной методике оценивали по уровню стабильных метаболитов NO: эндогенного нитрита, нитрата, общей концентрации метаболитов NO. РЕЗУЛЬТАТЫ: В группе животных, которым проводили доставку NO, статистически значимо выше средний уровень трансмембранного потенциала митохондрий (171,66 ± 20,41 vs 126,66 ± 18,61; p = 0,00256) и кальций-связывающей способности митохондрий (1466,66 ± 216,02 vs 866,66 ± 216,02; p = 0,000712) почечной паренхимы. Содержание метгемоглобина выше рекомендованных в клинической практике пороговых значений не было зарегистрировано в группе ИК+NO. Показатели общей концентрации метаболитов NO и нитратов статистически значимо выше в группе ИК+NO по сравнению с группой ИК, р = 0,00006; р = 0,0035 соответственно. ВЫВОДЫ: Плазмохимический синтез оксида азота является безопасной технологией, а применение полученного оксида азота на фоне искусственного кровообращения приводит к снижению выраженности митохондриальной дисфункции в паренхиме почек

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

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    Results of a search for H → τ τ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV respectively. All combinations of leptonic (τ → `νν¯ with ` = e, µ) and hadronic (τ → hadrons ν) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standard deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalised to the Standard Model expectation, of µ = 1.43 +0.43 −0.37 is consistent with the predicted Yukawa coupling strength in the Standard Model

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations
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