150 research outputs found

    SU(2) Skyrme Vortices

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    A regular method for constructing vortex-like solutions with cylindrical symmetry to the equations of the SU(2) Skyrme chiral model is proposed. A numerical estimate for the length density of mass is given

    The pipeline oil pumping engineering based on the Plant Wide Control technology

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    This article provides recommendations for the use technology Plant Wide Control to control the pumping of oil through the pipeline. The proposed engineering using pipeline management in general (Pipe Wide Control) will reduce the loss of electric power at the expense of the balance of pumping stations located along the pipeline route

    Instability of coherent states of a real scalar field

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    We investigate stability of both localized time-periodic coherent states (pulsons) and uniformly distributed coherent states (oscillating condensate) of a real scalar field satisfying the Klein-Gordon equation with a logarithmic nonlinearity. The linear analysis of time-dependent parts of perturbations leads to the Hill equation with a singular coefficient. To evaluate the characteristic exponent we extend the Lindemann-Stieltjes method, usually applied to the Mathieu and Lame equations, to the case that the periodic coefficient in the general Hill equation is an unbounded function of time. As a result, we derive the formula for the characteristic exponent and calculate the stability-instability chart. Then we analyze the spatial structure of the perturbations. Using these results we show that the pulsons of any amplitudes, remaining well-localized objects, lose their coherence with time. This means that, strictly speaking, all pulsons of the model considered are unstable. Nevertheless, for the nodeless pulsons the rate of the coherence breaking in narrow ranges of amplitudes is found to be very small, so that such pulsons can be long-lived. Further, we use the obtaned stability-instability chart to examine the Affleck-Dine type condensate. We conclude the oscillating condensate can decay into an ensemble of the nodeless pulsons.Comment: 11 pages, 8 figures, submitted to Physical Review

    Dynamical Toroidal Hopfions in a Ferromagnet with Easy-Axis Anisotropy

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    Three-dimensional toroidal precession solitons with a nonzero Hopf index, which uniformly move along the anisotropy axis in a uniaxial ferromagnet, have been found. The structure and existence region of the solitons have been numerically determined by solving the Landau-Lifshitz equation.Comment: 6 pages, 4 figure

    Exact Self-consistent Particle-like Solutions to the Equations of Nonlinear Scalar Electrodynamics in General Relativity

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    Exact self-consistent particle-like solutions with spherical and/or cylindrical symmetry to the equations governing the interacting system of scalar, electromagnetic and gravitational fields have been obtained. As a particular case it is shown that the equations of motion admit a special kind of solutions with sharp boundary known as droplets. For these solutions, the physical fields vanish and the space-time is flat outside of the critical sphere or cylinder. Therefore, the mass and the electric charge of these configurations are zero.Comment: 17 pages, Submitted to the International Journal of Theoretical Physic

    Use of Levosimendan in Cardiac Anesthesiology

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    The authors consider the main aspects of the rational use of the novel inotropic drug levosimendan in cardiosurgical patients on the basis of the results of the trials described in the literature and on their own findings in this review. The purpose of the analysis made was to provide a rationale for the effective use of this drug. The review shows the role of the ultrasound indicator left ventricular ejection fraction, the prognostic scale EuroSCORE, and the natriuretic peptides NT-proBNP and BNP in defining indications for levosimendan administration for preoperative preparation. There are original data on the lower level of the natriuretic peptides due to levosimendan therapy. The target hemodynamic monitoring values indicating that it is essential to use levosimendan in postperfusion heart failure are discussed. It is shown that it is expedient to use levosimendan simultaneously with traditional medical measures, by taking into account the pharmacokinetic features of a calcium sensitizer. The problem of levosimendan readministration in patients operated on the heart as well is stated. That there are no clear algorithms for repeated use of the drug is shown. At the same time, possible options of this therapy in different clinical situations are given. Key words: levosimendan, cardiosurgery, heart failure

    Professional Doctorates: International Experience and Russian Context

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    The diversification of forms and types of doctoral programs is currently a global trend. Universities across the globe offer programs that differ in the modes of training, characteristics of the target audience, and possible labor markets after graduation. In Russia, doctoral education exists in a unified format, focusing primarily on the academic labor market. Recently, there have been discussions about the need to expand the range of programs and the types of academic degrees in Russia. In this article, we present the analysis of professional doctoral programs: in response to what challenges and needs they appeared, how they are implemented, in what forms they exist. In addition, we consider the Russian experience of implementing professional doctoral programs; analyze the existing opportunities and barriers for their development. Based on the analysis, we came to a conclusion about the relevance of the professional doctoral programs’ development in Russia, the expediency of simplifying the conditions for their implementation and legitimizing special requirements for the design of dissertations with an applied orientation

    An integrated approach to the registration and preservation of a cultivar gene pool in the VIR genebank exemplified in cultivars bred by the Ural Federal Agrarian Research Center of the Ural Branch of the Russian Academy of Sciences

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    As part of a comprehensive program for registering and preserving the gene pool of Russian varieties in the VIR genebank, initiated at the N.I. Vavilov All-Russian Institute of Plant Genetic Resources, nomenclatural standards were assigned to potato cultivars ‘Alâska’, ‘Argo’, ‘Bravo’, ‘Irbitskij’, ‘Legenda’, ‘Lûks’, ‘Terra’, and ‘Šah’, and a voucher specimen was prepared for pre-cultivar ‘Bagira’. All of them were bred at the Ural Federal Agrarian Research Centre (Ural Branch of the Russian Academy of Sciences). Nomenclatural standards of these cultivars are preserved in the Nomenclatural standard collection at the Herbarium of cultivated plants and their wild relatives and weeds (VIR Herbarium, WIR). For each of them, a genetic passport was developed using DNA preparations isolated from plant material donated by the cultivar author to the VIR herbarium. The genetic passport, which includes information on the allelic composition of eight chromosome-specific microsatellite loci, is supplemented by the molecular screening data with markers of 11 R-genes for resistance to pests, as well as the data on the types of cytoplasm. The author of cultivars also supplied VIR with samples of virus-free in vitro plants. Microplants of eight Ural cultivars and one pre-cultivar were genotyped using the same SSR markers and included in the VIR in vitro collection, and then in the cryopreservation program. Most of the accessions were characterized by a relatively high, above 39%, level of post-cryogenic regeneration. Frozen explants of the genotyped Ural cultivars (‘Alâska’, ‘Argo’, ‘Legenda’, ‘Terra’, and ‘Šah’) and pre-cultivar ‘Bagira’ were placed for long-term storage in the VIR Cryobank

    Complexity and Expressivity of Branching- and Alternating-Time Temporal Logics with Finitely Many Variables

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    We show that Branching-time temporal logics CTL and CTL*, as well as Alternating-time temporal logics ATL and ATL*, are as semantically expressive in the language with a single propositional variable as they are in the full language, i.e., with an unlimited supply of propositional variables. It follows that satisfiability for CTL, as well as for ATL, with a single variable is EXPTIME-complete, while satisfiability for CTL*, as well as for ATL*, with a single variable is 2EXPTIME-complete,--i.e., for these logics, the satisfiability for formulas with only one variable is as hard as satisfiability for arbitrary formulas.Comment: Prefinal version of the published pape

    Трансанальное и трансабдоминальное укрепление колоректального аппаратного анастомоза как метод профилактики его несостоятельности: обзор литературы

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    The decrease of frequency of postoperative complications and leakage of colorectal anastomosis is one of the most important and actual problem of colorectal surgery. The formation of preventive stoma is a standard method of colorectal anastomotic leakage prevention. However, this method can bear to postoperative complications and disable patients. In this review article we discuss the results of transabdominal and transanal reinforcement of colorectal anastomosis as a method of leakage prevention.Одна из наиболее важных и актуальных задач колоректальной хирургии — снижение частоты послеоперационных осложнений в целом и несостоятельности колоректального анастомоза в частности. В качестве метода профилактики несостоятельности колоректального анастомоза стандартно прибегают к формированию превентивной стомы. Однако данный метод может приводить к возникновению послеоперационных осложнений, а также инвалидизирует больного. В данном обзоре литературы представлен мировой опыт применения другого метода профилактики несостоятельности анастомоза — дополнительного укрепления анастомоза, как трансабдоминального, так и трансанального
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