349 research outputs found

    Spine-sheath polarization structures in four active galactic nuclei jets

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    We present the results of multifrequency (15 + 8 + 5 GHz) polarization Very Long Baseline Array (VLBA) observations of the three BL Lacertae objects 0745 + 241, 1418 + 546 and 1652 + 398 together with 5-GHz VLBI Space Observatory Programme (VSOP) observations of 1418 + 546 and 1.6- and 5-GHz VSOP observations of the blazar 1055 + 018. The jets of all these sources have polarization structure transverse to the jet axis, with the polarization E vectors aligned with the jet along the jet spine and 'sheaths' of orthogonal E vectors at one or both edges of the jet. The presence of polarization aligned with the jet near the 'spine' may indicate that the jets are associated with helical B fields that propogate outward with the jet flow; the presence of orthogonal polarization near the edges of the jet may likewise be a consequence of a helical jet B field, or may be owing to an interaction with the ambient medium on parsec scales. We have tentatively detected interknot polarization in 1055 + 018 with E aligned with the local jet direction, consistent with the possibility that the jet of this source is associated with a helical B field

    Floristic Phenomena of the Samara Bend: The Fractal Organization of Taxonomic Diversity

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    Considering the problem of taxonomic diversity as a fractal object is the aim of this article. The prerequisites for such an approach were articles with varying degrees of detail and argumentation that substantiate taxonomic diversity from the standpoint of fractal geometry. Common to these papers is that the authors in their theoretical constructs start from the Willis rule (law) describing the rank distribution of the relationship between the number of taxa and their volume. The flora of the Samara Bend (the bend of the Volga River in its middle reaches) has become an object of the research. The authors distinguish seven basic floristic areas on the Samara Bend, the boundaries of which coincide with the respective landscapes. The authors discuss the efficiency of the Willis rule (law), which approximates the relationship between the number of taxa and their volume by rank distribution. The multifractal spectrum (a generalized geometric image of generic structure) of the taxonomic diversity of vascular plants of the Samara Bend is presented. Keywords: taxonomic diversity, fractal organization, Samara Ben

    Accelerated synthesis of Sn-BEA in fluoride media:effect of H<sub>2</sub>O content in the gel

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    Sn-BEA synthesis in concentrated gels results in 2.5–4 fold reduction of crystallization time and formation of smaller zeolite crystals.</p

    The place of anatomical museum in teaching phisiology for non-medical specialities students: traditionsand innovations

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    Рассмотрен опыт сотрудничества кафедры иммунохимии УрФУ с анатомическим музеем УГМА. Проведение практических занятий по физиологии человека для студентов немедицинских специальностей на базе музея позволяет повысить наглядность преподавания и активизировать познавательную деятельность студентов.Experience of co-working of immunochemistry chair of UrFU and anatomical museum of USMA is described. Teaching physiology in museum for non-medical specialities students increases illustrativity of teaching and studying activity of students

    Island model with genetic algorithm for solution of crystal structure from X-ray powder diffraction data

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    In this paper, we consider the problem of the study of polycrystalline substances: restoration of a substance atomic structure by full-profile analysis of powder diffraction data. This task is specific since it is not necessary to find very good solutions on average, but it is necessary to find the best one at least sometimes. To solve this problem, it is proposed to use an evolutionary algorithm based on the cooperative island model. The article describes the main stages and features of the algorithm and notes the qualitative advantages of this model in comparison with other methods (including evolutionary). The description of innovations proposed and the results of computational experiments are given. Conclusions from the experimental results are given, and further prospects for improving the efficiency of this method were noted

    Density of States and Conductivity of Granular Metal or Array of Quantum Dots

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    The conductivity of a granular metal or an array of quantum dots usually has the temperature dependence associated with variable range hopping within the soft Coulomb gap of density of states. This is difficult to explain because neutral dots have a hard charging gap at the Fermi level. We show that uncontrolled or intentional doping of the insulator around dots by donors leads to random charging of dots and finite bare density of states at the Fermi level. Then Coulomb interactions between electrons of distant dots results in the a soft Coulomb gap. We show that in a sparse array of dots the bare density of states oscillates as a function of concentration of donors and causes periodic changes in the temperature dependence of conductivity. In a dense array of dots the bare density of states is totally smeared if there are several donors per dot in the insulator.Comment: 13 pages, 15 figures. Some misprints are fixed. Some figures are dropped. Some small changes are given to improve the organizatio

    The equation of vapor-phase sorption on heterogeneous surfaces with local Guggenheim-Anderson-De Boer model

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    Recently, we proposed a new four-parametric MGAB equation (modified Guggenheim-Anderson-De Boer equation, GAB) for fitting of experimental isotherms of vapor-phase sorption on geosorbents. In the present study, the theoretical meaning of MGAB equation was elucidated. For this purpose, the properties of the equation of multilayer adsorption on a heterogeneous surface with local characteristics described by GAB model and Zeldovitsh-Roginskiy energy distribution function ρ(ε) were derived and the satisfaction of MGAB equation with these properties was shown. MGAB model has two parameters connected with GAB model: vm is the monolayer sorption capacity and k is the constant of the multilayer sorption, as well as two parameters of sorption energy distribution function ρ(ε): α, characterizing heterogeneity of ρ(ε) and C0, reflecting energy baseline. The influence of parameters α and C0 on the shape of both ρ(ε) and model sorption isotherm was established. The applicability of MGAB model for the description of surface heterogeneity of a natural sorbent by example of 13 different sorbate-sorbent systems dried and moistened has been discussed. For these systems equilibrium sorption isotherms were measured, corresponding energy distribution functions ρ(ε) were calculated, and obtained α values were compared. On the whole, the differences in α values responded to the real tendencies of heterogeneity changes in these systems. © 2006 Elsevier B.V. All rights reserved

    Прогнозирование степени перегрузки правых камер сердца у пациентов с острой массивной тромбоэмболией легочной артерии на основании результатов КТ-диагностики

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    The study group included 147 patients at the stage of preparation for emergency surgical treatment of acute massive PE in the period from March 2012 to December 2019 inclusive. As CT indicators of overload of the right chambers of the heart, the usual CT indicators that do not require the use of expert – class computed tomographs were taken – they were the superior vena cava, inferior vena cava, unpaired vein; reflux of the contrast drug into the inferior vena cava; reflux of the contrast drug into the hepatic veins. In the course of the study, a comparative analysis of the average pressure in the pulmonary artery with the above CT indicators was performed. The most stable statistical relationship with the indicators of mean pressure in the pulmonary artery was demonstrated by CT parameters – the diameter of the unpaired vein and the reflux of the contrast agent into the hepatic veins. Based on the results of the work, a method for calculating the actual values of the average pressure in the pulmonary artery based on the CT parameter of the diameter of the unpaired vein is proposed.В группу исследования вошло 147 пациентов на этапе подготовки к экстренному хирургическому лечению острой массивной тромбоэмболии легочной артерии (ТЭЛА) в период с марта 2012 г. по декабрь 2019 г. включительно. В качестве КТ-показателей перегрузки правых камер сердца взяты обычные КТ-показатели, не требующие использования компьютерных томографов экспертного класса, ими стали верхняя полая вена, нижняя полая вена, непарная вена; рефлюкс контрастного препарата в нижнюю полую вену; рефлюкс контрастного препарата в печеночные вены. В ходе исследования проведен сравнительный анализ среднего давления в легочной артерии с вышеуказанными КТ-показателями. Наиболее устойчивую статистическую взаимосвязь с показателями среднего давления в легочной артерии продемонстрировали КТ-параметры – диаметр непарной вены и рефлюкс контрастного препарата в печеночные вены. По результатам работы предложена методика расчета фактических значений среднего давления в легочной артерии на основании КТ-параметра “диаметр непарной вены”

    Phylogenetic Diversity of Urban Floras in the Central Urals

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    Modern cities harbor a high diversity of plants, and urban floras are significantly different from non-urban floras especially when considering the proportion of alien species found in cities. However, it is not clear whether urban areas disproportionately select for species from relatively few evolutionary lineages or provide opportunities for species across the full spectrum of plant lineages. Here, we examined the taxonomic and phylogenetic diversity of the floras in four cities (Yekaterinburg, Kamensk-Uralsky, Krasnoufimsk, and Turinsk) in the understudied region of Central Urals (Russian Federation). We classified native species into indigenous and apophytic species, namely, those that are sensitive to anthropogenic disturbance and those that have expanded their range with human activity, respectively. Alien species were classified into archaeophytes and neophytes according to when they were introduced (i.e., before or after than 1800). Phylogenetic diversity was quantified using Faith’s index to reflect total evolutionary history in urban areas and mean phylogenetic distance (MPD) to reflect species dissimilarity. Phylogenetic diversity of native species was higher than that for alien species, and the standardized effect size (SES) of MPD for natives was positive, reflecting their general dissimilarity from one another, while it was very negative for aliens, showing that they were phylogenetically clustered. However, among natives, apophytes were significantly clustered, while indigenous species were overdispersed. For the aliens, MPD was higher for archaeophytes compared to neophytes, though both groups were significantly clustered. These results show that urbanization leads to a non-random selection of plants. Apophytes and alien plants were composed of closely related species, reflecting similar ecological traits and are likely to be pre-adapted to the environmentally altered and highly disturbed urban environment. © Copyright © 2021 Tretyakova, Yakimov, Kondratkov, Grudanov and Cadotte.Funding for this collaboration was provided to MC by the Connaught Global Challenges Award, the Office of the Vice-President International, the School of Graduate Studies at the University of Toronto, the Office of the Vice-Principal Research at the University of Toronto Scarborough, and funding from the Natural Sciences and Engineering Research Council of Canada (#386151). This work was supported in part by the Program for Improving the Competitiveness of the Ural Federal University (the decree no. 211 of the Government of the Russian Federation, contract no. 02.A03.21.0006) and by the Russian Foundation for Basic Research (project no. 19-04-01084)
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