Saint Petersburg, Russia
Saint Petersburg, Russia

Saint Petersburg State University is a Russian federal state-owned higher education institution based in Saint Petersburg the oldest and one of the largest universities in Russia.It is made up of 22 specialized faculties, 13 research institutes, the Faculty of Military Studies, the Academic Classical School, the Medical College, the College of Physical culture and Sports, Economics and Technology and the Department of Physical Culture and Sports. As of 2014, the university has a teaching staff of 5,800. The university has two primary campuses: one on Vasilievsky Island and the other in Peterhof. During the Soviet period, it was known as Leningrad State University , in 1948–1989 named after Zhdanov. Wikipedia.

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Rydalevskaya M.A.,Saint Petersburg State University
Physica A: Statistical Mechanics and its Applications | Year: 2017

In this work, a simplified method for the evaluation of equilibrium composition of plasmas consisted of monoatomic species is proposed. Multicomponent gas systems resulting from thermal ionization of spatially uniform mixtures are assumed enough rarefied to be treated as ideal gases even after multiple ionization steps. The method developed for the calculation of equilibrium composition of these mixtures makes use of the fundamental principles of statistical physics. Equilibrium concentrations of mixture components are determined by integration of distribution functions over the space of momentum and summation over electronic energy levels. These functions correspond to the entropy maximum. To determine unknown parameters, the systems of equations corresponding to the normalization conditions are derived. It is shown that the systems may be reduced to one algebraic equation if the equilibrium temperature is known. Numeral method to solve this equation is proposed. Special attention is given to the ionized mixtures, generated from the atoms of a single chemical species and the situations, when in the gas only the first- or the first- and second-order ionization are possible. © 2017 Elsevier B.V.

Vechernin V.V.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

In the framework of the model with fusion of quark–gluon strings on the transverse lattice, we find the asymptotic behavior of the correlation coefficients between observables in separated rapidity intervals with a high string density in a realistic case with an inhomogeneous distribution of strings in the impact parameter plane. We calculate the asymptotic forms for three types of correlations: between the average transverse momenta of particles with rapidity in these intervals, between the average transverse momentum of particles in one rapidity interval and the multiplicity of particles in another, and also between the multiplicities of charged particles in these intervals. We show that the previously found independence of the asymptotic form of the correlation coefficient between the average transverse momenta from the variance in the number of particles produced in string fragmentation holds only in the case of a uniform distribution of strings in the transverse plane. We also show that the found general expressions for the long-range correlation coefficients in the particular case with a uniform distribution of strings in the transverse plane become the formulas previously obtained by another method applicable only in this simple case. © 2017, Pleiades Publishing, Ltd.

Lyakhovsky V.D.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

We propose a new algorithm for the character expansion of tensor products of finite-dimensional irreducible representations of simple Lie algebras. The algorithm produces valid results for the algebras B3, C3, and D3. We use the direct correspondence between Weyl anti-invariant functions and multivariate second-kind Chebyshev polynomials. We construct the triangular trigonometric polynomials for the algebra D3. © 2017, Pleiades Publishing, Ltd.

Marachevsky V.N.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

We solve the diffraction problem for electromagnetic waves on a planar (2+1)-dimensional layer with a given Chern–Simons action. The Casimir energy of a system of two parallel planar Chern–Simons layers is expressed in terms of the coefficients of reflection from separate layers. © 2017, Pleiades Publishing, Ltd.

Isozaki H.,University of Tsukuba | Korotyaev E.L.,Saint Petersburg State University
Russian Journal of Mathematical Physics | Year: 2017

We show the existence of a real analytic isomorphism between the space of the impedance function ρ of the Sturm–Liouville problem −ρ−2(ρ2f′)′ +uf on (0, 1), where u is a function of ρ, ρ′, ρ″, and that of potential p of the Schrödinger equation −y″ +py on (0, 1), keeping their boundary conditions and spectral data. This mapping is associated with the classical Liouville transformation f → ρf, and yields a global isomorphism between solutions of inverse problems for the Sturm–Liouville equations of the impedance form and those of the Schrödinger equations. © 2017, Pleiades Publishing, Ltd.

Braun M.A.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

We calculate the Casimir energy of the electromagnetic field in the one-dimensional space between two metallic plates filled with a dispersive and absorptive dielectric in the framework of a microscopic approach in which the medium is modeled by a set of oscillators with continuously distributed frequencies. We analyze the treatment of singular expressions used in other papers and show that with appropriate regularization and omission of certain infinite terms, the results coincide with those obtained in an approach without such singularities. We study the asymptotic behavior at large distances and conclude that it always corresponds to attraction, but the influence of the dielectric can lead to repulsion at finite distances. © 2017, Pleiades Publishing, Ltd.

Starodubtsev A.N.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

We study the dynamics of a massive pointlike particle coupled to gravity in four space–time dimensions. It has the same degrees of freedom as an ordinary particle: its coordinates with respect to a chosen origin (observer) and the canonically conjugate momenta. The effect of gravity is that such a particle is a black hole: its momentum becomes spacelike at a distances to the origin less than the Schwarzschild radius. This happens because the phase space of the particle has a nontrivial structure: the momentum space has curvature, and this curvature depends on the position in the coordinate space. The momentum space curvature in turn leads to the coordinate operator in quantum theory having a nontrivial spectrum. This spectrum is independent of the particle mass and determines the accessible points of space–time. © 2017, Pleiades Publishing, Ltd.

Ezhovskii Y.K.,Saint Petersburg State University
Russian Journal of Physical Chemistry A | Year: 2017

The formation of nanolayers of silicon and aluminum oxides, obtained by means of molecular layering (or atomic layer deposition (ALD technology)) on surfaces of GaAs, InAs, and InSb, is investigated. Conditions for the layer-wise growth of surface nanostructures are established, and some of their dielectric characteristics are estimated. © 2017, Pleiades Publishing, Ltd.

Shamtsyan M.,Saint Petersburg State University
Journal of Hygienic Engineering and Design | Year: 2016

From prehistoric times mushrooms have been used not only for nutrition but also for healing purposes. At present there are already several hundred species of mushrooms for which there are known various therapeutic properties, and which can be used as dietary supplements or for fortification of food with functional compounds. In vitro and in vivo studies on immune modulating, antitumor, hypocholesterolic, hypolipidemic, antidiabetic and other effects were performed. Enzymatic activities were studied using appropriate substrates. Immune-modulating effect of rich with beta-glucans mushroom extracts was demonstrated. It was shown, that studied extracts also have antitumor effect. Hypocholesterolic, hypolipidemic, antidiabetic, milk-clotting, and other effects of uptake of mushroom extracts were clearly shown. Besides well-known immune modulating and anti-tumor effects, mushrooms possess other valuable properties including antioxidant, anti-hypertensive, cholesterol-lowering, liver protection, anti-obesity, anti-inflammatory, anti-diabetic, anti-microbial and some others. Mushrooms also can be a source of various enzymes useful for food industry. © 2016, Consulting and Training Center - KEY. All rights reserved.

Kuznetsov S.R.,Saint Petersburg State University
Mathematical Biology and Bioinformatics | Year: 2015

This work is devoted to development of mathematical model, describing processes of Th and B lymphocyte proliferation and differentiation, as well as IFN-$\gamma$, IL-2, IL-4 and IL-21 cytokine secretion. New approaches are suggested, allowing more accurate modelling. Special attention paid to Th17 lymphocyte impact to effect of plasma cells and IgM and IgG antibody level increasing.

Averianov A.,Saint Petersburg State University | Sues H.-D.,Smithsonian Institution
Cretaceous Research | Year: 2017

There are 24 known localities for skeletal remains of sauropod dinosaurs in the republics of Central Asia (Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan). Sauropod remains are very rare at all these localities and represented usually only by isolated teeth. Only narrow-crowned teeth are known from the Cretaceous of Central Asia. The oldest record of such teeth is from the Aptian Sultanbobo Formation of Uzbekistan. Exposures of the Turonian Bissekty Formation at the most productive vertebrate locality in the region, Dzharakuduk in Uzbekistan, has yielded many isolated teeth and a few skeletal remains that can be attributed to a non-lithostrotian titanosaur. Similar narrow-crowned, cylindrical teeth from Cenomanian-to Coniacian-age strata in the Kyzylkum Desert, Uzbekistan, may belong to a closely related taxon. Another taxon, with teeth that are pentagonal in cross-section, is known from the Santonian Yalovach and Bostobe formations of Tajikistan and western Kazakhstan, respectively. A femur reported from the Santonian Syuksyuk Formation of southern Kazakhstan possibly belongs to a lithostrotian titanosaur. The change in tooth structure at the Coniacian–Santonian boundary in the region possibly suggests replacement of non-lithostrotian titanosaurs by lithostrotians. The titanosaur from the Bissekty Formation is similar to Dongyangosaurus sinensis from the Cenomanian–Turonian of Zhejiang (China) in the extensive pneumatization of the neural arch on the anterior caudal vertebrae with several fossae. It also resembles Baotianmansaurus henanensis from the Cenomanian of Henan (China) in the possession of very short anterior caudal centra. These three taxa possibly represent an as yet formally unrecognized endemic clade of Asian non-lithostrotian titanosaurs. © 2016 Elsevier Ltd

Churilov L.P.,Saint Petersburg State University
Psychiatria Danubina | Year: 2016

The article is devoted to biographies of three Russian physicians of the Silver Age (a period in the History of Russian culture between 1890 and 1917). They made early, significant and internationally recognized contribution into medical science and became eponymous, although social disasters of the twentieth century caused deep impact on their subsequent lives and careers, so their role was shadowed from global medical community. The article analyzes biographies and academic achievements of A-F.K. Siewert (aka: Zivert, Ziwert, von Siewert) (1872-1922), known for first description of the hereditary dyskinesia of cilia (as a triad of: situs inversus of the viscera, abnormal frontal sinuses producing sinusitis and bronchiectasis); S.S. Abramov (1875-1951), discoverer of primary idiopathic myocarditis, and N.I. Taratynov (1887-1919), who was the first in description of a local form of histiocytosis X (solitary eosinophilic granuloma) and predicted the eosinophilic origin of Charcot-Leyden crystals. The contribution of these scientists into Medicine is reviewed in context of historical epoch, on background of their different individual social choices and the fate of their families. Besides their eponymous descriptions, other medical priorities of these scholars are analyzed. Some previously unpublished materials from their family archives are presented, which witness for possible existence of unknown prototype for the main hero of 'Doctor Zhivago' novel by B. L. Pasternak and for probable priorities of doctor Zivert -in active diastole concept, or doctor Abramov -in description of dilated cardiomyopathy. The factors facilitating rapid development of theoretical and practical Medicine in imperial Russia of late XIX -early XX centuries are discussed. The conclusion of the author is that in any epoch, even the most cruel and unfavorable one, the creative activity is a way to social immortality (19 figs, 68 refs). © Medicinska naklada - Zagreb, Croatia.

Titov A.I.,Saint Petersburg State University
SPIIRAS Proceedings | Year: 2016

The article describes the main effort estimation models for software development. It is spoken in detail about the most widely used software effort estimation model, the Constructive Cost Model (COCOMO). An approach to improve the accuracy of estimates of COCOMO model based on neural network approximation is proposed. It deals with the choice of a neural network with back-propagation errors as an approximator. Data are given about numerical results of neural network learning using COCOMO model parameters as input.

Jackalin L.,KTH Royal Institute of Technology | Dvinskikh S.V.,KTH Royal Institute of Technology | Dvinskikh S.V.,Saint Petersburg State University
Zeitschrift fur Physikalische Chemie | Year: 2017

We present natural abundance nitrogen-15 (NAN15) NMR spectroscopy in thermotropic liquid crystals. It is demonstrated that high resolution NAN15 NMR spectra in mesophases can be accurately recorded in non-spinning samples with a high orientational molecular order and strong anisotropic spin interactions. In this technique, due to low demand on radio-frequency decoupling power, standard solution-state probes can be used, which generally provide superior sensitivity and spectroscopic resolution in comparison to solid-state probes. We show that 15N chemical shift anisotropy (CSA) can be used as a sensitive probe of molecular orientational dynamics in liquid crystals. This method is exploited here to measure the orientational molecular order parameter of the nematic 4-pentyl-4′-cyanobiphenyl (5CB). Since the nitrogen spectra are obtained from the molecules constituting the mesophase rather than from probe molecules, the information is direct and the analysis and interpretation is straightforward. Nitrogen CSA of immobilized molecules, required in the analysis, is obtained using a DFT calculation. The approach provided consistent results for the order parameter in the nematic 5CB in the whole temperature range, in good agreement with literature data. © 2017 Walter de Gruyter GmbH, Berlin/Boston 2017.

Dolgopolik M.V.,Saint Petersburg State University | Fradkov A.L.,Saint Petersburg State University
Nonlinear Analysis: Hybrid Systems | Year: 2017

In this article, nonsmooth extensions of the Speed-Gradient (SG) algorithms in differential and finite forms are proposed. The conditions ensuring achievement of the control goal (convergence of the goal function to zero) are established. Furthermore, conditions under which the control goal is achieved in finite time with the use of nonsmooth or discontinuous SG algorithms are obtained. Theoretical results are illustrated by example of nonsmooth energy-based control for a non-affine in control pendulum-like system. © 2017 Elsevier Ltd

Abiev R.S.,Saint Petersburg State University
Theoretical Foundations of Chemical Engineering | Year: 2017

The theoretical description of nonlinear liquid oscillations in pulsation bulk-capacity apparatuses has been considered. A mathematical model of liquid oscillations in a pulsation apparatus of generalized shape with elbows of variable cross sections has been constructed, and the obtained differential equations have been solved by the harmonic balance method and the Fourier expansion of the amplitude of oscillations in the levels of liquid in apparatus elbows. It has been shown that it is necessary to take into account at least four expansion term including the constant one and the phase shift at least of the first-order harmonic to obtain a satisfactory description of liquid oscillations in the considered system. Pronounced fundamental, second- and third-order superharmonic, and 1/2- and 1/3-order subharmonic system oscillations and the possibility of 2/3- and 3/2-order combined-frequency system oscillations have been revealed. The constructed model enables one to calculate the frequency of natural oscillations in pulsation apparatuses, including oscillations with greats amplitude at which their nonlinearity produced by a nonlinear character of the Mendeleev–Clapeyron equation in resilient members cannot be neglected. In combination with the calculated amplitudes of oscillations, this will provide the possibility of determining liquid velocities and passing to the calculations of other hydrodynamic parameters. © 2017, Pleiades Publishing, Ltd.

Astashkevich S.A.,Saint Petersburg State University
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2017

A systematic study of the dependences of information inequalities relating the variance, Fisher information, and Shannon entropy power in the coordinate and momentum spaces (the Cramér–Rao, Stam, Bialynicki–Birula–Mycielsky–Beckner, and other inequalities) on the vibrational quantum number of a diatomic molecule is performed for the first time. These dependences are calculated for the ground electronic state of the 7Li2 molecule using the semiempirical data available in the literature on the many-parameter potential curve of this state. Specific features of these dependences have been analyzed, their essentially nonmonotonic behavior was revealed, and not only quantitative, but also qualitative, distinctions between these dependences were observed. These results were compared with the results of our calculation in the classical mechanics approximation, and significant (up to a factor of 3.5) discrepancies between these data were observed not only for low-lying, but also for highly excited vibrational levels that are close to the dissociation limit. The results obtained can be used in quantum informatics, analysis of an intramolecular structure and the interaction processes involving the vibrational states of diatomic molecules. © 2017, Pleiades Publishing, Ltd.

Galkin A.P.,Saint Petersburg State University
Current Genetics | Year: 2017

Discovery of prions—proteins that are able to convert between structurally distinct states, of which one or more is transmissible, led to the concept of “protein-based inheritance”. According to this concept, the formation of prion fibrils causes DNA-independent heritable traits in microorganisms. Recently, we described a new and unusual type of prion inheritance. We showed that the yeast prions [PIN+] and [SWI+], like classical genes, demonstrate complementary interaction that causes a phenotypic change in yeast cells. Here, we discuss the possible mechanisms of such polyprionic inheritance and the perspectives in the identification of prions in various organisms using universal proteomic approaches. © 2017 Springer-Verlag Berlin Heidelberg

Korneev V.G.,Saint Petersburg State University
IOP Conference Series: Materials Science and Engineering | Year: 2016

Efficiency of the error control of numerical solutions of partial differential equations entirely depends on the two factors: accuracy of an a posteriori error majorant and the computational cost of its evaluation for some test function/vector-function plus the cost of the latter. In the paper consistency of an a posteriori bound implies that it is the same in the order with the respective unimprovable a priori bound. Therefore, it is the basic characteristic related to the first factor. The paper is dedicated to the elliptic diffusion-reaction equations. We present a guaranteed robust a posteriori error majorant effective at any nonnegative constant reaction coefficient (r.c.). For a wide range of finite element solutions on a quasiuniform meshes the majorant is consistent. For big values of r.c. the majorant coincides with the majorant of Aubin (1972), which, as it is known, for relatively small r.c. (< ch -2 ) is inconsistent and looses its sense at r.c. approaching zero. Our majorant improves also some other majorants derived for the Poisson and reaction-diffusion equations. © Published under licence by IOP Publishing Ltd.

Galaktionov K.V.,Saint Petersburg State University
Biology Bulletin | Year: 2016

The review deals with the biodiversity, life cycles, distribution and temperature adaptations of parasites circulating in the coastal waters of northern polar seas. Special attention is given to helminths of marine birds, which are the most common parasites in the coastal waters. Among them, the focus is on trematodes. Factors responsible for the impoverished species composition of parasites in the Arctic are analyzed. It is shown that species without free-living larvae in the life cycle have an advantage in this environment. The abundance of cestodes and acanthocephalans in Arctic seabirds is linked with the high proportion of crustaceans in their diet. The phenomenon of nonspecific parasitism (occurrence of parasites in atypical host species) is analyzed from an evolutionary viewpoint. Characteristic features in the spatial distribution of infection of marine coastal invertebrates with parasite larvae are considered, and factors that determine it are specified. The prevalence of infection in intermediate hosts is closely connected with the abundance of final hosts, which makes it possible to estimate the abundance of final hosts in a given region and reveal trends in its changes. Trematodes have a high potential for temperature acclimation. This facilitates their transmission in the northern seas but, on the other hand, makes it unlikely that the transmission process would be intensified upon an increase in summer temperatures resulting from climate warming. However, intensification of transmission may well occur due to the prolongation of the warm season (“transmission window”), which has been predicted and is already observed. It is suggested that warming in the Arctic promotes both the entry of certain “southern” species into the Arctic and the trans-Arctic interpenetration of the North Atlantic and North Pacific parasitic faunas. A case is made for the necessity to broaden the scope of parasitological research in the Arctic and Subarctic, including parasitological monitoring at the reference sites of the sea coast. © 2016, Pleiades Publishing, Inc.

Vinarski M.V.,Saint Petersburg State University
Biology Bulletin | Year: 2016

The reality of ecological and local races was investigated in two widespread Palearctic species of lymnaeid snails (Lymnaea stagnalis and Radix auricularia). Several methods of statistical analysis were used, including two-way ANOVA, cluster analysis, and discriminant analysis for six plastic shell characters. It was shown that none of the methods used could convincingly demonstrate that ecological and local races were present in the studied species. Even in cases when statistically significant differences among the populations in the morphology of shells were revealed, these differences were very small and did not correspond to the meaning that was put into the concept of “race” by malacologists in the past. Perhaps, the formation of such races in pond snails is possible only in case of populations being formed in suboptimal conditions, for example, in thermal springs or at large depths. This being the case, the distinguishing of races requires using other shell characters, both quantitative and qualitative ones. © 2016, Pleiades Publishing, Inc.

Smirnova E.,Saint Petersburg State University | Alexeev M.,Saint Petersburg State University
Environmental Science and Pollution Research | Year: 2017

The article considers optimizing methods for wastewater treatment systems. Nutrients (nitrogen and phosphorus) are discharged from the river basin of the northwest Russia. Disruption of ecological safety and healthy state of water basins takes place when excess amount of nitrogen and phosphorus is discharged from wastewater. This results in eutrophication that is increased growth of seaweeds and, therefore, in ecological system disruption. The cities of the northwest region are short of funds for renovation of water treatment systems. However, the new solution lies in improvement of biological water treatment system by means of chemical injection. The main research task is implementation of methods for enhanced biological phosphorus removal from domestic sewage. The problem of recycling and ecological safety of rivers within the northwest of Russia and the Baltic Sea is not solved completely. That is why for wastewater dephosphorization, the authors suggest using sulfuric acid production waste at chemical plant “Ammophos,” Cherepovets (ferrous sulfate FeSO4·7H2O and phosphogypsum СаSO4·Р2О5), as reagents. The advantage of these reagents is their low cost. The authors show the efficiency of the new optimal reagent’s combination. Filtering the wastewater through sand filters after secondary settlers increases the total phosphorus removal efficiency up to 90%. The high effect of all types of phosphorus and total nitrogen removal from wastewater can be resulted from the features of micelle creation during coagulation. © 2017 Springer-Verlag Berlin Heidelberg

Ivanov A.O.,Saint Petersburg State University
Bulletin of Geosciences | Year: 2016

A chondrichthyan assemblage is described from the Early Permian (Artinskian and Kungurian) of Mechetlino Quarry (Bashkortostan, South Urals). The assemblage includes the teeth of a symmoriiform, a sphenacanthid euselachian and an anachronistid neoselachian, as well as various denticles and scales. The dentition of Cobelodus aculeatus has been restudied. The teeth of a new genus of symmoriiform shark are described as Kungurodus, the internal structure of which is reconstructed using microtomography. © 2016, Czech Geological Society. All rights reserved.

Krupenko D.,Saint Petersburg State University | Gonchar A.,Saint Petersburg State University
Parasitology International | Year: 2017

Cercariae of digenean family Notocotylidae are characterized by a set of morphological traits which make them easily distinguishable from any other. One of the key features is absence of ventral sucker. This affects basic ways of locomotion and attachment. To understand how these functions are fulfilled we studied musculature arrangement in cercariae of two species by means of fluorescent-phalloidin staining and confocal microscopy. We used Cercaria Notocotylidae sp. No. 11 and 12 Deblock, 1980 from mud snails Ecrobia (= Hydrobia) ventrosa. Information on gross morphology (especially body-tail junction) and basic behavioural patterns of these cercariae is also updated. Major special features of musculature are associated with the ventral concavity: extreme development of dorsoventral muscle fibres and formation of annular arrangement of longitudinal muscle fibres on the ventral side. Additional body-wall and internal muscle bundles in the anterior region are also specific for notocotylid cercariae and seem to play important role in twisting movements during substratum testing. Musculature of dorsal adhesive pockets, oral sucker and tail is also described. These results are discussed in relation to observed locomotory patterns. © 2017 Elsevier B.V.

Semenov B.N.,Saint Petersburg State University
Materials Physics and Mechanics | Year: 2017

To evaluate the effect of graphene inclusions on deformation characteristics of nanocomposite "metal-graphene" the finite element analysis of representative volume deformation followed by homogenization of the mechanical properties deformation is performed and the dependence of effective modules and plastic flow on the concentration of graphene inclusions is studied. It is shown that the influence of inclusions on the modulus of elasticity and plasticity limit of the nanocomposite is not significant. Graphene inclusions effect on strength and fracture toughness of the composite "(nano) metal-graphene". The results of finite-element simulations indicate that in the nanocomposite a decrease in stress concentration in vicinity of the crack tip is observed when approaching the crack tip to the graphene inclusion enable. © 2017, Peter the Great St. Petersburg Polytechnic University.

Porubov A.,Saint Petersburg State Polytechnic University | Andrievsky B.,Saint Petersburg State University
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2017

A general form of a distributed feedback control algorithm based on the speed-gradient method is developed. The goal of the control is to achieve nonlinear wave localization. It is shown by example of the sine-Gordon equation that the generation and further stable propagation of a localized wave solution of a single nonlinear partial differential equation may be obtained independently of the initial conditions. The developed algorithm is extended to coupled nonlinear partial differential equations to obtain consistent localized wave solutions at rather arbitrary initial conditions. © 2017 The Author(s) Published by the Royal Society. All rights reserved.

Khantuleva T.A.,Saint Petersburg State University | Shalymov D.S.,Saint Petersburg State University
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2017

The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a nonequilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed. © 2017 The Author(s) Published by the Royal Society. All rights reserved.

Smirnova O.M.,Saint Petersburg State University
Magazine of Civil Engineering | Year: 2016

Application of polycarboxylate-based superplasticizers can contribute to the increase of concrete early strength. It makes possible to obtain the concrete of the required strength after heat-steaming treatment with decreasing the isothermal temperature and the Portland cement quantity compared to the concrete without admixtures. Reducing of water-cement ratio and lack of accelerated high-temperature of heat-steaming treatment raises the durability of precast concrete. The use of low heat-steaming treatment must not lead to an increase of the duration of treatment and reduction of productivity of plant with double turnover of moulds per day. It is necessary to take into account the compatibility of Portland cement and polycarboxylate-based superplasticizers to obtain the high concrete strength after heat-steaming treatment. The problem of the compatibility of Portland cement and polycarboxylate-based superplasticizers in precast concrete production contains the following items: the influence of chemical and mineralogical compositions of Portland cement on the water-reducing effect of polycarboxylate-based superplasticizers, on the retention of workability of fresh concrete as well as on the growth of early concrete strength. Most of the published papers contain the results received when investigating the cement paste. However, the effect of polycarboxylate-based superplasticizers in stiff fresh concrete has not yet been fully investigated. The optimal dosages of polycarboxylate-based superplasticizers, requirements to the granulometric and chemical-mineralogical compositions of Portland cements with the purpose of reducing the cement consumption and providing the required concrete strength after the heat-steaming treatment at 40 °C have been defined. © Smirnova O.M., 2016.

Krasil'nikov N.N.,Saint Petersburg State University
Journal of Optical Technology (A Translation of Opticheskii Zhurnal) | Year: 2016

We propose a hypothesis for the mechanism that ensures coordination of saccadic movements of the eye when observing real objects or images of real objects, including stereoscopic images. We show that angular screen parallaxes cannot exceed a certain critical value for viewing of stereoscopic images to be free of image doubling or viewer discomfort. We also demonstrate that the distance interval over which a stereoscopic image can be viewed without image doubling rapidly decreases as the viewing distance decreases; this does not support high transmission quality of spatial depth under typical viewing conditions for television broadcasts, where viewing distances are short; by contrast, high quality can be achieved in cinematography, where the viewing distances are relatively long. The use of 3D virtual-reality helmets has been proposed to increase the apparent depth of field in 3D television broadcasts. © 2017 Optical Society of America.

Nefedov V.,Saint Petersburg State University
Proceedings of the Institution of Civil Engineers: Urban Design and Planning | Year: 2017

The paper considers the peculiarities of the territorial growth of the St Petersburg periphery and the problems of nature conservation as part of the ecological framework of the city. The author’s attention is concentrated on the search for such an alternative solution of urban development, which would ensure the gradual formation of the natural infrastructure, integrated with new residential buildings and transport space. A number of alternative approaches to the creation of ecologically balanced environment in the periphery of St Petersburg is offered on the basis of the situation analysis in the city and the consideration of international experience. The author’s core task in the urban periphery development is providing vital spaces for people’s social and cultural interaction at their residence in the natural environment. An analysis of several conflict situations in the peripheral part of the city indicates the need of change of the town planning paradigm, which is capable of ensuring the coordination of the natural, engineering, transport and social infrastructure. The change from land use planning and management mainly for the multistorey building to the formation of integrated nature and architectural spaces of acceptable scale is demonstrated through several projects. © 2017, ICE Publishing. All rights reserved.

Kharitonov V.L.,Saint Petersburg State University
Automatica | Year: 2017

In this contribution an extension of the prediction-based design scheme proposed in Tsubakino et al. (2015) for compensation of input delays to the case of systems with input and state delays is presented. To derive safely implementable control laws we propose to apply additional input filters and obtain a closed-loop system in the form of a set of retarded type differential equations. An example illustrating the design scheme is given. © 2017 Elsevier Ltd

Parshin S.G.,Saint Petersburg State University
Welding International | Year: 2017

The results of investigation of the process of MAG welding S235JR carbon steel with the addition of SF6 gaseous sulphur hexafluoride with concentrations from 1.6 to 6.4% carbon dioxide are described. The aim of the investigations was to improve the droplet metal transfer and the formation of the welded joint in MAG CO2 welding in carbon dioxide. The addition of the SF6 sulphur hexafluoride to the carbon dioxide changes the process of melting of the electrodes, decreases the extent of splashing and shortens the short-circuiting time. The droplet transfer frequency increases by up to 1.6 times, the depth of penetration increases to 66% and the width of the welded joint decreases to 36%. The welding current increases in a wide range of the welding conditions, the arc voltage decreases, together with the amplitude of the deviation of the current and arc voltage. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Marchuk A.A.,Saint Petersburg State University | Sotnikova N.Y.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2017

We present a modification of the method for reconstructing the stellar velocity ellipsoid (SVE) in disc galaxies. Our version does not need any parametrization of the velocity dispersion profiles and uses only one assumption that the ratio σz/σR remains constant along the profile or along several pieces of the profile. The method was tested on two galaxies from the sample of other authors and for the first time applied to three lenticular galaxies NGC 1167, NGC 3245 and NGC 4150, as well as to one Sab galaxy NGC 338. We found that for galaxies with a high inclination (i > 55°-60°) it is difficult or rather impossible to extract the information about SVE, while for galaxies at an intermediate inclination the procedure of extracting is successful. For NGC 1167 we managed to reconstruct SVE, provided that the value of σz/σR is piecewise constant. We found σz/σR = 0.7 for the inner parts of the disc and σz/σR = 0.3 for the outskirts. We also obtained a rigid constraint on the value of the radial velocity dispersion σR for highly inclined galaxies, and tested the result using the asymmetric-drift equation, provided that the gas rotation curve is available. © 2016 The Authors.

Voshchinnikov N.V.,Saint Petersburg State University | Henning T.,Max Planck Institute for Astronomy | Il'In V.B.,St. Petersburg State University of Aerospace Instrumentation
Astrophysical Journal | Year: 2017

We interpret the interstellar extinction observed toward the Galactic center (GC) in the wavelength range λ = 1-20 μm. Its main feature is the flat extinction at 3-8 μm whose explanation is still a problem for cosmic dust models. We search for the structure and chemical composition of dust grains that could explain the observed extinction. In contrast to earlier works, we use laboratory measured optical constants and consider particles of different structures. We show that a mixture of compact grains of aromatic carbon and of some silicate is better suited for reproducing the flat extinction in comparison with essentially porous grains or aliphatic carbon particles. Metallic iron should be located inside the particle, i.e., it cannot form layers on silicate grains as the extinction curves then become very peculiar. We find a model including aromatic carbonaceous particles and three-layered particles with an olivine-type silicate core, a thin, very porous layer and a thin envelope of magnetite that provides a good (but still not perfect) fit to the observational data. We suggest that such silicate dust should be fresh, i.e., recently formed in the atmospheres of late-type stars in the central region of the Galaxy. We assume that this region has a radius of about 1 kpc and produces about half of the observed extinction. The remaining part of extinction is caused by a "foreground" material being practically transparent at . © 2017. The American Astronomical Society. All rights reserved..

Fedorkov A.,Russian Academy of Sciences | Gutiy L.,Saint Petersburg State University
Silva Fennica | Year: 2017

Mortality, stem growth and quality of lodgepole pine (Pinus contorta var. latifolia) originating from the six Swedish seed orchards and local Scots pine (Pinus sylvestrisL.) were estimated in four field trials established in the Komi Republic (north-west Russia). A randomized row-plot design with 6–12 replicates of each entry was used. The tree mortality was slightly higher for Scots pine than that for lodgepole pine, except for the lodgepole pine seed sources of the southern origins with lower survival. Scots pine stem quality was better than that of lodgepole pine, but the lodgepole pine stem growth was faster except the seed source of the southernmost origin. The lodgepole pine seed sources of northern origins had better stem growth (height, diameter at breast height and volume), while the effect of latitude on the quality traits was insignificant. © 2017, Finnish Society of Forest Science. All rights reserved.

Smirnova O.,Saint Petersburg State University
Procedia Engineering | Year: 2017

The paper presents the recommendations on the concrete production for the precast prestressed reinforced concrete constructions (sleepers, etc.) with double turnover forms per day by using the integrated approach, involving the use of ordinary raw materials, effective modifiers of concrete structure, low-temperature of heat-steaming treatment. Such concretes should provide the required transfer strength (strength at the moment of release tension bars) in a relatively short time 10-12 hours. The implementation of the following measures requires for obtaining the high-performance concrete for sleepers in the conditions of the existing technological equipment of domestic plants: increasing the density of cement stone due to the use of water-reducing admixtures, improving the structure of concrete due to the use of low heat-steaming treatment, the account of activity of Portland cement at low temperature of heat-steaming treatment, use of active mineral component. © 2017 The Authors.

Kossukhina M.A.,Saint Petersburg State University
2016 IEEE 5th Forum Strategic Partnership of Universities and Enterprises of Hi-Tech Branches, Science. Education. Innovations 2016 | Year: 2016

The paper presents a methodology for the selection of business - models for technology commercialization centers (TCC), based on educational institutions, using the analytic hierarchy process. The types of technology commercialization centers business models and their applicability to the TCC are also considered. © 2016 IEEE.

Syromyatnikov A.V.,Saint Petersburg State University | Sizanov A.V.,RAS Petersburg Nuclear Physics Institute
Physical Review B - Condensed Matter and Materials Physics | Year: 2017

We discuss a magnetically ordered ("superfluid") phase near quantum transition to the Bose-glass phase in a simple modeling system, a Heisenberg antiferromagnet with spatial dimension d>2 in an external magnetic field with disorder in exchange coupling constants. Our analytical consideration is based on hydrodynamic description of long-wavelength excitations. Results obtained are valid in the entire critical region near the quantum critical point (QCP), allowing us to describe a possible crossover from one critical behavior to another. We demonstrate that the system behaves in full agreement with predictions by M. P. Fisher et al. [Phys. Rev. B 40, 546 (1989)PRBMDO0163-182910.1103/PhysRevB.40.546] in close vicinity to the QCP. We find as an extension to that analysis that the anomalous dimension η=2-d and β=νd/2, where β and ν are critical exponents of the order parameter and the correlation length, respectively. The density of states per spin of low-energy localized excitations is found to be independent of d ("superuniversal"). We show that many recent experimental and numerical results obtained in various three-dimensional (3D) systems can be described by our formulas using percolation critical exponents. Then, it is a possibility that a percolation critical regime arises in the ordered phase in some 3D systems not very close to the QCP. © 2017 American Physical Society.

Alekseev N.P.,Saint Petersburg State University
Breastfeeding Medicine | Year: 2017

Background: Severe breast engorgement can cause substantial discomfort for mothers and interfere with an infant's ability to feed at the breast. The aim of the study was to clarify the possibility that the percutaneous progesterone-containing gel (Progestogel) can eliminate severe postpartum breast engorgement in lactating women. Subjects and Methods: Twenty three patients were examined. The Progestogel for transdermal therapy in an amount of 2.5-3 g was applied to the breast. Before application and 20 min after application the density of the mammary glands was measured by a tonometer. Results: According to our observations, within 20 min application of 2.5-3 g of the Progestogel on the breast skin does not result in reducing breast swelling, engorgement and tenderness. Conclusions: After 20 minutes, transdermal application of Progestogel does not reduce the degree of engorgement of the mammary glands in the postpartum period. © 2017, Mary Ann Liebert, Inc.

Popov I.Y.,Saint Petersburg State University
Biology Bulletin | Year: 2017

In recent studies nine populations of the freshwater pearl mussel have been described in the Baltic Sea basin in Russia. They are very scarce, although the condition of their habitats seems to be rather good. Overfishing of the host fish is a limiting factor for them. The number of salmon has decreased by at least 100 times over the past 200 years. Such a scale of decline tends to be hidden over time, and estimation of the normal conditions of the salmon–pearl mussel ecosystem becomes problematic. A significant increase in the number of salmon is necessary to prevent extinction of pearl mussels. Effective protected areas appear to be the only possibility for conservation of the pearl mussels and its host fish species. © 2017, Pleiades Publishing, Inc.

Kavokin K.,Saint Petersburg State University
PLoS ONE | Year: 2017

While many properties of the magnetic compass of migratory birds are satisfactory explained within the chemical model of magnetoreception, its extreme sensitivity to radiofrequency magnetic fields remains a mystery. Apparently, this difficulty could be overcome if the magnetoreceptor model were augmented with a magnetite nanoparticle, which would amplify the magnetic field at the position of the magneto-sensitive cryptochrome molecule. However, comparison of the radio-frequency power used in the experiment with intrinsic magnetization noise of such a particle, estimated from the theory of fluctuations, shows that the required sensitivity cannot be reached with realistic parameters of iron-oxide nanocrystals. © 2017 Kirill Kavokin. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Tipikin Iu.A.,Saint Petersburg State University
CEUR Workshop Proceedings | Year: 2016

The problem of reliability and stability of high performance computing parallel jobs become more and more topical with the increasing number of cluster nodes. Existing solutions rely mainly on inefficient process of RAM dumping to stable storage. In case of really big supercomputers, such approach - making checkpoints - may be completely unacceptable. In this study, I examined the model of distributed computing - Actor model - and on this basis I developed an algorithm of batch jobs processing on a cluster that restores interrupted computation state without checkpoints. The algorithm is part of a computing model that, to be specific, I called "control flow kernels model in the name of its core component - control kernel. This work describes all the components of the new model, its internal processes, benefits and potential problems. © 2016 Iurii A. Tipikin.

Braun M.A.,Saint Petersburg State University
European Physical Journal C | Year: 2017

Hadron–nucleus amplitudes at high energies are studied in the “toy” Regge model in zero transverse dimension for finite nuclei, when the standard series of fan diagrams is converted into a finite sum and loses physical sense at quite low energies. Taking into account all the loop contributions by numerical methods we find a physically meaningful amplitudes at all energies. They practically coincide with the amplitudes for infinite nuclei. A surprising result is that for finite nuclei and small enough triple pomeron coupling the infinite series of fan diagrams describes the amplitude quite well in spite of the fact that in reality the series should be cut and as such deprived of any physical sense at high energies. © 2017, The Author(s).

Veretenenko S.V.,Saint Petersburg State University
Bulletin of the Russian Academy of Sciences: Physics | Year: 2017

Effects of solar proton events (SPEs) and Forbush decreases of galactic cosmic rays (GCRs) on the evolution of baric systems at middle latitudes are compared. It is shown that SPEs with particle energies >90МeV contribute to more intensive regeneration of cyclones at Arctic fronts, while Forbush decreases of GCRs are accompanied by intensification of anticyclonic processes at Polar fronts. The data show that changes in the ionization rate caused by cosmic ray variations play an important part in solar-atmospheric relationships. © 2017, Allerton Press, Inc.

Yarevsky E.,Saint Petersburg State University | Yakovlev S.L.,Saint Petersburg State University | Elander N.,Albanova University Center
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2017

An approach based on splitting the reaction potential into a finite range part and a long range tail part to describe few-body scattering in the case of a Coulombic interaction is proposed. The solution to the Schrödinger equation for the long range tail of the reaction potential is used as an incoming wave. This reformulation of the scattering problem into an inhomogeneous Schrödinger equation with asymptotic outgoing waves makes it suitable for solving with the exterior complex scaling technique. The validity of the approach is analyzed from a formal point of view and demonstrated numerically, where the calculations are performed with the finite element method. The method of splitting the potential in this way is illustrated with calculations of the electron scattering on the hydrogen atom and the positive helium ion in energy regions where resonances appear. © 2017 IOP Publishing Ltd.

Manuilov A.S.,Saint Petersburg State University
Technical Physics | Year: 2017

Kinetic methods are used to derive the transport equations, virial equation, dynamic equilibrium condition, and the equation of the envelope of an axially symmetric paraxial relativistic electron beam propagating in an Ohmic plasma channel during the evolution of resistive firehose instability. The equation of the beam envelope is generalized by taking this instability into account. © 2017, Pleiades Publishing, Ltd.

Grigoryev Al.A.,Saint Petersburg State University
Vestnik Sankt-Peterburgskogo Universiteta, Seriya Geologiya i Geografiya | Year: 2016

Based on the analysis of factors of exogenous relief formation, the article discusses the genesis of the anthropomorphic and zoomorphic forms of relief. Science is dominated by the view that such stone sculptures, found all over the planet, are a "game" of nature. It is claimed, confidently and without evidence, that they were created by various natural processes. In the spread of animal and anthropomorphic forms of relief there are certain patterns that indicate their anthropogenic origin. They occur very selectively in certain locations under different geological-geomorphological and climatic conditions. At the same time on the other sites with similar environments to the places of their distribution they are absent. Many of these forms are confined to river valleys or to watershed locations convenient for the settlement of geographical space. The list created by the forms are limited to only some living things, well known to modern man. Distribution features of "fancy" morphosculpture rule out its natural Genesis and suggest its natural and anthropogenic origin. This conclusion is also supported from the position of consideration of anthropomorphic and zoomorphic shapes as also megaliths - the elements and indicators of the development of ancient geographical space. Refs. 14. Figs. 5.

Kayukova E.P.,Saint Petersburg State University
Vestnik Sankt-Peterburgskogo Universiteta, Seriya Geologiya i Geografiya | Year: 2016

The stable isotopic and tritium content of precipitation and groundwater were studied in the Crimean Mountains. Stable isotopes of water (δ18O and δ2H) and tritium were used to assess sources of water in the shallow groundwater and surface-water systems, and to better understand groundwater/surface-water interactions. The δ18O values of groundwater range from -10,3 to -8,7 %o with corresponding δ2H values of-65,2 to -59,6 %o. These are mainly scattered along the local meteoric water line, meaning meteoric origin. The weighted average concentration of stable isotopic δ18O and δ2H in the rainfall (>17mm/day) for the summer season of 2013 were approximately -7,9 and -55,6 %o respectively. Formation of groundwater is caused by the infiltration of precipitation. Additional information has been obtained from tritium data. Refs 15. Figs 7. Tables 9.

Ivanova-Kazas O.M.,Saint Petersburg State University
Paleontological Journal | Year: 2016

A complicated, almost conflicting situation exists in contemporary biology, i.e., there are two scientific concepts in existence that solve some phylogenetic problems in a different way. These concepts are evolutionary morphology and molecular biology. Modern biology urgently needs these contradictions to be examined and removed. © 2016, Pleiades Publishing, Ltd.

Cherepanov G.O.,Saint Petersburg State University
Paleontological Journal | Year: 2016

The turtle shell is characterized by a high degree of conservatism of the fundamental model and, at the same time, a high variability at the individual level. The components of the bony shell vary in origin. The costal and neural plates of the carapace are modified elements of the axial skeleton (ribs and neural arches) and the plastral plates are transformed dermal ossifications of the shoulder girdle and gastralia, peripheral, pygal, and suprapygal plates are similar to osteoderms of other reptiles. The variability of the structure of particular parts of the turtle shell is manifested differently. Most anomalies have been recorded in the caudal part of the carapace. The plastron is relatively stable in morphology. Variations in the bony shell structure are observed in (1) unusual shape and size of plates combined with normal number of plates, (2) presence of additional plates, and (3) absence of regular plates. Based on the morphogenetic characteris-tics, anomalies are subdivided into (1) variations caused by changes in the number of elements of the axial skeleton or their contacts with the dermis (neurals and costals); (2) variations due to changes in the number of horny scutes (peripherals); (3) variations connected with irregular osteogeny or disturbed growth of bones © 2016, Pleiades Publishing, Ltd.

Petrova N.,Saint Petersburg State University
Psychiatry, Psychotherapy and Clinical Psychology | Year: 2016

Review of the literature showed that anxiety commonly co-occurs with bipolar disorders (BDs), but the significance of such "co-morbidity" remains not clarified and its optimal treatment can not be adequately defined. Nearly half of BD patients meet diagnostic criteria for an anxiety disorder at some time. Such co-morbidity is associated with poor treatment reactions, substance abuse, invalidism. Prevalence of this co-morbidity appears to be greater among women than men, but similar in BD types I and II. Anxiety may be more likely in depressive phases of BD, but relationships of anxiety phenomena to particular phases of BD and their temporal distributions require clarification. Benzodiazepines are sometimes given empirically; antidepressants are employed cautiously to limit risks of mood switching and emotional destabilization; lamotrigine, valproate, and secondgeneration antipsychotics may be useful and relatively safe.

Saulina E.,Saint Petersburg State University
Psychiatry, Psychotherapy and Clinical Psychology | Year: 2016

This report presents one part of the results of the author's PhD thesis about peculiariyties of sexual dimorphism of cognitive abilities of adolescents with high and average IQ. The sample group comprised 249 children aged 14-17 years from about 50 Russian schools. The group was divided into two subgroups: 1) 132 adolescents, 81 girls and 51 boys, with high general IQ (hereafter - gifted); 2) 117 teenagers, 66 girls and 51 boys, with average IQ. Scores of 11 intellectual abilities were measured by the Universal Test of Intelligence Investigation "UIT". The program SPSS Statistics 20 was applied for processing mathematical data. The main results are that only adolescents with high IQ show the sexual dimorphism of intellectual abilities: girls have better results than boys at verbal (p=0.001), spatial abilities (p=0.05), short-term memory (p=0.001); boys have better results at mathematic abilities (p=0.001). Adolescents with average IQ didn't show sex diff erences in the level of cognitive abilities. This fact allows to suggest that the level of IQ is an important factor for prediction sex diff erences in a cognitive development. The gifted girls show higher spatial abilities than boys (it is unusual among diff erent researches of this topic). One of the factors of giftedness is the increased level of testosterone in the early stage. Testosterone for women has positive correlation with the level of spatial abilities, men have negative correlation. The sex diff erences caused by high testosterone can explain the higher scores for gifted girls.

Khryashchev S.M.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Control systems with a finite number of control parameters (dynamical polysystems) are considered. It is assumed that a polysystem functions in continuous time, and switchings of control occur in some discrete instants of time. The control goal is a transition of a polysystem from some initial state to arbitrary final state. Controllability of the polysystems is studied. Statistic methods are applied. Some probability characteristics of dynamical polysystems are defined. It is shown that under the rank condition, the switching controls always exist. The values of control times can be found by some numerical methods. © 2015 IEEE.

Ponomarev A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Model predictive control of a nonlinear dynamical system with linearizable and Lipschitz right-hand side is studied. It is proven that the exact model predictive control feedback allows approximation with a piecewise-affine, possibly discontinuous, function defined by its precalculated values on a finite grid. Approximation is understood not in the sense that control values are close but rather in the sense of closeness of the cost values. Additionally, if such approximation is close enough, stability of the approximate MPC is proven. © 2015 IEEE.

Golovkina A.G.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Two-point reactor kinetics model which makes it possible to take into account spacial fuel inhomogeneity in the reactor core better than the well-known point kinetics model is proposed. Calculation results using point and proposed kinetics model for homogeneous and heterogeneous reactor cores are presented. © 2015 IEEE.

Voloshin M.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In this paper, sufficient conditions of the uniform ultimate boundedness of solutions for a class of non-stationary systems of difference equations are derived. To obtain these conditions, the Lyapunov direct method is used. © 2015 IEEE.

Abdushukurov D.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Being in a good progress, the particle accelerators start to penetrate deeply into different sectors of human social life. Application of accelerator technology, to address a variety of new tasks, places special demands on the characteristics of the charged particles beam, such as reducing the size of the beam, rigorous requirements for the form of the beam and the calibration of its energy. This paper proposes methods for determining tolerances in the parameters of the systems elements to accelerate and focus the charged particles beams. The offered methods are based on differential calculus, matrix formalism and algebraic techniques Lee, tensor matrix computation. The submitted mathematical apparatus represents the parallelization of computations on the presented methods. © 2015 IEEE.

Ershov D.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The problem of limited resource extraction by two firms often occurs in practice. Both firms try to maximize their income. This issue has been thoroughly investigated in [2]. The difficulty lies in the fact that the model uses a system of differential equations, which do not have analytic solution. In this paper, an attempt was made to improve the model in order to the obtained systems with analytic solution, which could be analyzed. © 2015 IEEE.

Rogovskiy S.T.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Solution of the problem of a hinged band-shaped plate, weakened by a crack parallel to the bearings, is found. The crack is assumed to be loaded with a bending moment and shear forces. Relation between the stress intensity factor at the crack tip, crack's location, and plate's parameters has been examined. © 2015 IEEE.

Rashchenko D.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The article considers two modifications (implementation the symmetry of ones and zeros and using the polarizer), which allow to use the advantages of the Hamming's neural network, such as speed and clearness of the criterion of similarity, in the neural network ART-1 with preservation its advantages, such as stability-plasticity. © 2015 IEEE.

Grigor'Eva X.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

A two-level hierarchical game of n + 1 persons with coalitional partition is considered. The control center is on the first level of the hierarchy, and the n players are on the second level. The players on the second level are formed coalitions. An algorithm for solving of this game is described. According to this algorithm PMS-vector, first introduced by Petrosyan L. A. and Mamkina S. I. [1], or generalized PMS-vector in mixed strategies [2] in a coalitional game between players from the lower level of the hierarchical game is found on the first step. Then game can be considered as a two-level hierarchical Stackelberg game of two persons [3], where control center is on the first level of the hierarchy and player with strategies which are Nash equilibrium situations from coalitional game of first step algorithm [4]. Then it is possible to find the Stackelberg strategy for the center on the second step algorithm. The existence of solution for suggested algorithm is proved. The algorithm is illustrated by a two-level hierarchical game coalitional partition with one center and three lower-level players. © 2015 IEEE.

Kirjanen A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

We consider a mathematical model of two investors competition and obtain coefficient criteria of asymptotic stability for nontrivial equilibrium when both competitors coexist. The problem was reduced to finding of coefficient criteria of stability in quasi-polynomial case (polynomial of the second order relatively ez and z). © 2015 IEEE.

Kozynchenko S.A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

At the present paper we consider the software designed for non-relativistic beam dynamics simulation and optimization in the injection systems. This software permits designing the injection system during optimization process, taking into account the output characteristics of the beam. It is developed on the Win32 platform, using dialog boxes and free integrated development environment such as Visual C++ Express, and possesses the necessary features such as an interactive input, real-time graphical and text output, start, stop, etc. © 2015 IEEE.

Matrosov A.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In this article a superposition method for analysing an orthotropic elastic rectangular with arbitrary boundary conditions is presented. Two solutions in trigonometric series derived by the method of initial functions are used to construct a general solution for a rectangle in 2-dimensional Cartesian coordinates. Boundary conditions lead to a system of linear algebraic equations over the unknown coefficieints of the series expansion of the general solution. The approach is used to analyse a clamped isotropic and orthotropic console rectangle. © 2015 IEEE.

Bazhanov P.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Positron emission tomography (PET) is a nuclear medicine technique that allows not only obtaining a three-dimensional image of internals, but also assessing their metabolism and functions, which helps to identify the disease at an early stage. Development of mathematical algorithms in PET is the crucial task because of wide range of applications for image reconstructions and projection data correction. © 2015 IEEE.

Fominyh A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In this paper the problem of optimal control in the classical statement is considered. With the help of the theory of exact penalty functions the original problem is reduced to the problem of unconstrained minimization of a nonsmooth functional. For this functional the necessary minimum conditions in terms of hypodifferential are found. A class of problems, for which these conditions are also sufficient, is distinguished. On the basis of these conditions the hypodifferential descent method is applied to the considered problem. Under some additional assumptions the hypodifferential descent method converges in a certain sense. © 2015 IEEE.

Tur A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The problem of strategically supported cooperation in linear-quadratic differential games is considered. It is assumed, that the cooperative agreement is reached and each player gets his payoff according to the payoff distribution procedure [5]. Following [3], to punish those who violate this agreement, the special game, which differs from initial only by payoffs of players on cooperative trajectory is constructed. It is shown that in the new game there exists an ε-equilibrium with payoffs of players equal to corresponding payoffs of players in cooperative solution of initial game. © 2015 IEEE.

Franus D.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Changes in the stress-strain state of the corneoscleral shell of the human eye after intravitreal injection are modeled in the ANSYS software package. Three different forms of the shell, representing the eye with normal vision (the emmetropic eye), the eyes with myopia (short-sightedness), and hyperopia (farsightedness) are considered. The corneoscleral shell is modeled by a transversely isotropic multi-layered corneal and single layer scleral shells, all the layers of which have different biomechanical properties. A comparison of deformations and volume changes in different occasions is made. © 2015 IEEE.

Angelov T.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Currently, a lot of approaches for finding extremum points of nonsmooth functions exists. In this paper the class of codifferentiable functions is studied. The algorithm for exact codifferential calculation, specially designed for effective computer implementation, is suggested. Application of the developed algorithm is illustrated in details on the example. © 2015 IEEE.

Zhabko N.A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The problem of parameter identification of nonlinear dynamic models in horizontal and vertical planes of autonomous underwater vehicle is considered in this paper. To estimate the parameters of nonlinear models the algorithm based on the prediction error minimization is proposed, and then the estimated nonlinear models are used to find the adequate linear model for motion control system synthesis. © 2015 IEEE.

Orekhov M.Y.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

This paper outlines issues of designing environments for real-time dynamic displaying of vector object-oriented 2D open-text formatted schemes with large number of rendered objects. Graphical objects and their dynamic behaviour are treated as entities with mutable structure-string-indexed containers. The article emphasizes significance of container elements rapid lookup by given key for application general performance. © 2015 IEEE.

2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

A nonlinear mechanical system with nonconservative forces, two-component homogeneous potential forces and control forces of a special form is considered. On the basis of the Lyapunov functions method, several theorems that provide sufficient conditions of asymptotic stability of system's equilibrium position and sufficient conditions of ultimate boundedness of its solutions are proved. © 2015 IEEE.

Rubtsova I.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

This article is devoted to intense beam dynamics optimization in resonance systems, where particles movement is effected by radio-frequency (RF) fields generated by the beam itself. Klystron or klystron-type buncher are the examples of such devices. Mathematical model of beam longitudinal dynamics is presented by the finite sequence of equations. At every iteration dynamic process is described by the system of integral-differential equations; right-hand part of this system depends on functionals values defined on beam trajectories at previous iteration. The controlled process efficiency is estimated by the criterion defined on trajectory ensemble of final iteration. Mathematical methods of trajectory ensemble control are developed and analytical expression of quality criterion variation is derived. This result makes it possible to obtain objective functional gradient and to use directed optimization methods. The approach suggested has been successfully applied for beam dynamics optimization in klystron-type buncher. © 2015 IEEE.

Tikhonov A.A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

A satellite with electrodynamic attitude control system is considered. The problem of compensation of an external disturbing torque is solved. The optimization of control process in vicinity of programmed motion is achieved on the basis of control system without involving additional measuring devices. © 2015 IEEE.

Krivovichev G.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Stability analysis of the system of lattice Boltzmann equations for 1D diffusion with respect to initial conditions is performed. Stability condition is obtained by the method of first differential approximation with representation of the solution in form of travelling wave. It is showed that solutions of the system are asymptotically stable for all values of physical parameters. Stability condition is the same as for the system of lattice Boltzmann equations for modelling of hydrodynamical processes. © 2015 IEEE.

Abbasov M.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Nature always inspires researchers of different fields. Physical analogies allow to get new efficient algorithms for various optimization problems. Well known and sufficiently studied heavy ball method is one of the representatives of such type of algorithm [1]-[8]. Another algorithm of this type is proposed in this work. It is developed for finding minimum distance between two convex sets. © 2015 IEEE.

Sheinman I.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Self-coordinated transverse dynamics of the high current relativistic electronic bunches used for generation of undulator radiation in wakeguides with dielectric filling is investigated. An analytical approach to solution of self-coordinated beam dynamics is developed. The received solution is used for investigation of the bunch flight range in dependance of parameters of dielectric wakefield structure. © 2015 IEEE.

Miheev S.E.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

Given the quantitative definition of attractiveness for investment in production. Studied its dependence on labor input. Found levers to stimulate labor-intensive industries in the form of a tax burden increase in resource-intensive production and its decrease in labor-intensive production. © 2015 IEEE.

Shakhov Y.A.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In this paper, the model of mathematical pendulum is formulated as a non-linear dynamic system. The equilibrium positions of the dynamic system are obtained as a solution of corresponding problem of multiprogram stabilization. This solution is eventually formalized in a form of Hermit's polynomial. © 2015 IEEE.

Korolev V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The multi-impulse and multi-criteria optimal trajectories of the spacecraft transfer between orbits of various types are considered. A practical goal is the inspection or service of a number of space objects moving along these orbits at the initial data set. It is required to define a set of the admissible solutions taking into account priorities and possible restrictions on time or on expenses of energy, and to choose the best of possible routes for successively visiting every object in the desired group. © 2015 IEEE.

Pavilaynen G.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The bending of the vertical beams caused by the SD-effect under a concentrated load at the end of the beam is considered. For the solution of the problem, the Ilyushin model of perfect plasticity is used. The problem is solved analytically and numerically. As an example of the material with the SD-effect A40X-steel is considered. The solutions for the beams made of an isotropic material and of a material with the SD-effect are compared. © 2015 IEEE.

Iakushkin O.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

The service systems deployed in a cloud environment have a volatile business logic which cannot be fully described by messaging patterns now available. Firstly, the work of distributed service systems is heavily influenced by the type, format, topic, and content of messages. Secondly, the existing middleware solutions for message exchange have a very narrow functionality focused exclusively on message passing between the nodes of a distributed system. They pay no attention to the features of the messages sent. However, scaling in hybrid and geo-distributed cloud solutions requires a more comprehensive approach. So does the analysis of the state of system modules. This paper offers an algorithm allowing to classify messages which are sent via the same protocol but have various content and do not correspond to a pre-set format. We provide an example of using such algorithm in middleware architecture. The major advantages and drawbacks of the algorithm are described with regard to a distributed cloud system. © 2015 IEEE.

Klyuenkov A.L.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In the present paper the dynamical difference input-output model is considered. The regional economy is simulated and analyzed based on the official data of Rosstat. A system of difference equations is constructed using aggregated data of Rosstat. We assume that the phase variables are annual outputs of three aggregated sectors and gross domestic product (GDP). Prediction of major economic indicators is produced. Predicted values of outputs and GDP are comparing with corresponding values that are predicted using the differential dynamical model. The main goal of the research is to develop an algorithm for solution finding in the optimization problem of macroeconomic trends. Main assumption is that the investment sources are external financial resources. This problem of optimal control for dynamical difference system is reduced to an interval problem of linear programming (IPLP) and finally solved using the adaptive method of R. Gabasov. © 2015 IEEE.

Ivanova K.F.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

New technique of deriving the guaranteed two-sided estimations of solutions set of interval systems of the linear algebraic equations (ISLAE) with the uncertain parameters is offered. The estimation algorithm is based on formalization of the equations with two point matrices and the right-hand sides of vectors-by the analysis of scalar component wise product of matrix entries and their cofactors. Through new matrices bottom and top borders of the interval determinant are established. Solutions of formalized point equations establish conformity between them and a known estimation of an exterior interval hull of the linear interval equations system. © 2015 IEEE.

Medvedeva I.V.,Saint Petersburg State University
2015 International Conference on "Stability and Control Processes" in Memory of V.I. Zubov, SCP 2015 - Proceedings | Year: 2015

In this paper, for a class of linear time-invariant systems with distributed delay, the robust stability conditions are obtained, and the exponential estimates for the solutions are constructed. The results are derived within the framework of the Lyapunov-Krasovskii functionals with a given derivative. The functional, that does not admit a quadratic lower bound and therefore is considered to be inappropriate for the robustness analysis, is used. © 2015 IEEE.

Akim E.L.,Saint Petersburg State University
Fibre Chemistry | Year: 2016

This article gives a brief review of our research over the 10 years that have passed since the Rogovin Lectures devoted to the 100th birthday of Z. A. Rogovin [1]. © 2016, Springer Science+Business Media New York.

Burinskii S.V.,Saint Petersburg State University
Fibre Chemistry | Year: 2016

A process for converting carbonized and graphitized cellulose-hydrate fiber cords with binding polyvinyl-alcohol fibers into carbon papers, strengthening their hardened phenolformaldehyde resin, and heat treating them in an inert medium at 900 and 2000°C was developed. © 2016, Springer Science+Business Media New York.

Kolesin I.D.,Saint Petersburg State University
Biophysics (Russian Federation) | Year: 2016

The relationship between pandemic morbidity and the shared participation of a pandemic variant in epidemic process has been studied based on the example of the first pandemic wave of the A(H1N1)pdm flu in Russia (2009–2010). The selection of the relationship type of variants and transfer of the self-regulation concept of the epidemic process to the development mechanism of pandemic wave has been substantiated. The role of the genetic drift of the pandemic strain has been explained. © 2016, Pleiades Publishing, Inc.

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2017

The subject and main areas of a new research field-cybernetical physics-are discussed. A brief history of cybernetical physics is outlined. The main areas of activity in cybernetical physics are briefly surveyed, such as control of oscillatory and chaotic behaviour, control of resonance and synchronization, control in thermodynamics, control of distributed systems and networks, quantum control. © 2017 The Author(s) Published by the Royal Society. All rights reserved.

Egorov A.V.,Saint Petersburg State University
2016 IEEE 55th Conference on Decision and Control, CDC 2016 | Year: 2016

This paper presents a criterion of exponential stability for time-invariant linear delay systems of retarded type. The criterion, which is based on the delay Lyapunov matrix, generalizes the Lyapunov stability theorem for ordinary differential systems. We show how to construct a special matrix, which is positive definite, if the system is exponentially stable, and is not positive definite otherwise. © 2016 IEEE.

Smirnov K.,Saint Petersburg State University
2016 15th International Symposium on Problems of Redundancy in Information and Control Systems, REDUNDANCY 2016 | Year: 2016

We consider a distributed WSNs with event-based reporting. A data gathering time is an important attribute for such systems. Due to that fact, a lot of media access protocols have been designed to meet special demands of particular applied application. To analyze and compare the variety of protocols the lower bound of data gathering time is required. In the paper we propose a special technique to determine a boundary value for mean data gathering time. The obtained general result takes into account an information on operating conditions of the system and system algorithms as well. We also derive some exact expressions for the particular most used models. © 2016 IEEE.

Pavlov V.S.,Saint Petersburg State University
2016 15th International Symposium on Problems of Redundancy in Information and Control Systems, REDUNDANCY 2016 | Year: 2016

The paper studies the accuracy characteristics of radar object angular coordinates estimation fulfilled by the spatially multichannel procedures, which are based upon a ring shaped model of radar signal receiving and differ among themselves by redundancy factor. It is shown in analytical evaluation that the spatial processing structures of minimal and ultimate redundancies are equate by potential accuracy criterion when signal-to-noise ratio is high, otherwise at the area of low signal-to-noise ratios the advancement of redundancy factor is resulted in estimation error reduction down to Cramer-Rao bound. © 2016 IEEE.

Maria S.,Saint Petersburg State University
2016 15th International Symposium on Problems of Redundancy in Information and Control Systems, REDUNDANCY 2016 | Year: 2016

In this work the mathematical model of transactions processing systems is described. For this model we propose a procedure of transformation of initial system, which makes it possible to calculate the lower bound of average transaction processing delay numerically. A few ways of the bound tightening are also discussed. © 2016 IEEE.

Apanasenko N.,Saint Petersburg State University
2016 15th International Symposium on Problems of Redundancy in Information and Control Systems, REDUNDANCY 2016 | Year: 2016

The article is devoted to the work of ultra-wideband data transmission systems with pulse position modulation (Time Hopping Spread-Spectrum) in presence of Gaussian noise mixture (Tukey-Huber contamination model). We considered data transmission for the cases of known and unknown parameters of a noise mixture. The optimal decision-making algorithm for known parameters of a distortion is developed. Sub-optimal iterative algorithm of decision-making for unknown parameters of noise mixture based on Estimation-Maximization algorithm is proposed. An efficiency of proposed approaches is compared with a conventional receiver. © 2016 IEEE.

Bauer S.,Saint Petersburg State University | Voronkova E.,Saint Petersburg State University
Shell Structures: Theory and Applications - Proceedings of the 10th SSTA 2013 Conference | Year: 2014

Refined 2D plate theories for orthotropic plates of moderate thickness are discussed. In these theories deformations, rotation and bending of the fibers and their elongations in the direction of the thickness of the shell are taken into account. The algebraic relationships for deflections and stresses, between solutions of the Kirchhoff-Love (KL) theory and the refined theories are presented. A three-dimensional mathematical model is numerically analyzed by the FEM code. Numerical results displacements and stresses determined by the presented theories are compared with the FEM results.

Altsybeev I.G.,Saint Petersburg State University
Journal of Physics: Conference Series | Year: 2017

Long-range correlations between particles separated by a pseudorapidity gap are a powerful tool to explore the initial stages and evolution of the medium created in hadron-hadron collisions. An overview of the long-range correlations measured by the ALICE detector in pp, p-Pb and Pb-Pb will be presented. This includes analyses of forward-backward, two- and multi-particle correlations with the use of the central barrel and forward detectors. © Published under licence by IOP Publishing Ltd.

Ryspaeva E.B.,Saint Petersburg State University
Journal of Physics: Conference Series | Year: 2017

We reanalysed the archival X-ray observations of double system AE Aquarii, obtained using orbital observatories «XMM-Newton» and «Chandra» in 2001 and 2005 respectively. We made an independent timing analysis with two numerical methods. Our result confirmed the presence of 33 s rotational period of white dwarf in the system. In addition, we confirmed that X-ray pulsations with a period of 16.5 s, which were detected in optical and UV ranges, absent in AE Aquarii spectrum. This may mean that the X-ray emission comes from one of the poles of white dwarf surface. © Published under licence by IOP Publishing Ltd.

Lazareva T.V.,Saint Petersburg State University
Journal of Physics: Conference Series | Year: 2017

The increase of luminosity of the SPS beams expected after 2020 allows considering the investigation of rather rare processes. In particular, so-called cumulative particle production can be studied in hadron collisions by measurements of secondary particle yields in regions kinematically forbidden for reactions with free nucleons. Such processes could be either a result of hard parton collisions with some large-density multi-quark configuration or of the formation of heavy baryonic resonances. Measurements in the backward hemisphere in fixed target experiment should provide the event-by-event data that could be used, along with those from the forward region, for a correlation analysis, thus resulting in new constraints on models. In this report the preliminary design, ideas, technology and the first GEANT simulations of a proposed new detector are presented and discussed. © Published under licence by IOP Publishing Ltd.

Vereshagin V.,Saint Petersburg State University
EPJ Web of Conferences | Year: 2016

To construct the reasonable renormalization scheme suitable for the effective theories one needs to resolve the problem of couplings because the number of free parameters in a theory should be finite. Otherwise the theory would loose its predictive power. In the case of effective theory already the first step on this way shows the necessity to solve the above-mentioned problem for the 1-loop 2-leg function traditionally called self energy. In contrast to the customary renormalizable models the corresponding Feynman graph demonstrates divergencies that require introducing of an infinite number of prescriptions. In the recent paper [1] it has been shown that the way out of this difficulty requires the revision of the notion of one-particle reducibility. The point is that in effective scattering theory one can introduce two different notions: the graphic reducibility and the analytic one. Below we explain the main ideas of the paper [1] and recall some notions and definitions introduced earlier in [2] and [3]. © 2016 The Authors, published by EDP Sciences.

Vechernin V.,Saint Petersburg State University
EPJ Web of Conferences | Year: 2016

The long-range correlation between mean-event transverse momenta, being robust against the volume fluctuations and the details of the centrality determination, enables to obtain the signatures of string fusion at the initial stage of hadronic interaction in relativistic heavy ion collisions. The dependence of the correlation strength between mean-event transverse momenta on the collision centrality and initial energy is analyzed in a simple model with quark-gluon string fusion on the transverse lattice. It is shown that above RHIC energy the dependence reveals the decline of the correlation coefficient for most central collisions, reflecting the attenuation of color field fluctuations due to the string fusion at large string density. It is also found that contrary to the correlation between transverse momenta of single particles the strength of the correlation between mean-event transverse momenta of particles in two separated rapidity intervals is not decreasing with the total number of produced strings, remaining significant even in the case of Pb-Pb collisions, in which the total number of strings can reach several thousand. © 2016 The Authors, published by EDP Sciences.

Lipatov L.N.,Saint Petersburg State University
EPJ Web of Conferences | Year: 2016

The high energy scattering in QCD and gravity can be described in terms of reggeized gluons and gravitons, respectively. At N = 4 SUSY the BFKL Pomeron is dual to the reggeized graviton living in the 10-dimensional anti-de-Sitter space. We discuss the corresponding effective actions for reggeized gluon and graviton interactions. The Euler-Lagrange equations for these effective theories are constructed with a variational approach and by using an invariance under the gauge and general coordinate transformations. We discuss their solutions and applications to the calculation of effective Reggeon vertices and trajectories. © 2016 The Authors, published by EDP Sciences.

Kovalenko V.,Saint Petersburg State University | Vechernin V.,Saint Petersburg State University
Journal of Physics: Conference Series | Year: 2017

We demonstrate that the investigations of the forward-backward correlations between intensive observables enable to obtain more clear signal about the initial stage of hadronic interaction, e.g. about the process of string fusion, compared to usual forward-backward multiplicity correlations. As an example, the correlation between mean-event transverse momenta of charged particles in separated rapidity intervals is considered. We performed calculations in the framework of dipole-based Monte Carlo string fusion model. We obtained the dependence of the correlation strength on the collision centrality for different initial energies and colliding systems. It is shown that the dependence reveals the decline of the correlation coefficient for most central Pb-Pb collisions at LHC energy. We compare the results both with the ones obtained in alternative models and with the ones obtained by us using various MC generators. © Published under licence by IOP Publishing Ltd.

Andronov E.,Saint Petersburg State University
EPJ Web of Conferences | Year: 2017

The main physics goals of the NA61/SHINE programme on strong interactions are the study of the properties of the onset of deconfinement and the search for signatures of the critical point of strongly interacting matter. For this purpose a scan of the two dimensional phase diagram (T-μΒ) is being performed at the SPS by measurements of hadron production in nucleus-nucleus collisions as a function of collision energy and system size. This contribution presents intriguing results on the energy dependence of hadron spectra and yields in inelastic p+p and centrality selected Be+Be and Ar+Sc collisions. In particular, the energy dependence of the signals of deconfinement, the "horn", "step" and "kink", and new results on fluctuations and correlations are shown and compared with the corresponding data of other experiments and model predictions. © The Authors, published by EDP Sciences, 2017.

Kovalenko V.,Saint Petersburg State University
EPJ Web of Conferences | Year: 2017

Long-range multiplicity correlations in intervals separated in pseudorapidity and azimuth are studied in the framework of string fusion approach. We applied a Monte Carlo model, in which the string configurations in the transverse plane and rapidity are simulating event-by-event. The string interaction is realized in the lattice string fusion approach with introduction of a grid in the transverse plane. We assumed that the azimuthal anisotropy of particle production is caused by parton energy loss traveling trough the media formed by clusters of fused strings: Δpt/Δx = -α(pt√ η)2/3, where η is a string density. In the cellular approach the Bresenham's line algorithm has been applied. It is obtained that in AA collisions, the parton energy loss seems to play considerable role, in particular, by providing large contribution to the correlation of mean transverse momentum with multiplicity. The developed approach provides non-zero values flows in p-Pb collisions at LHC energies and produces the pattern similar to the one of the experimental di-hadron analysis. © The Authors, published by EDP Sciences, 2017.

Kostrin D.K.,Saint Petersburg State University
Vakuum in Forschung und Praxis | Year: 2016

At the present stage of progress the development of ion-plasma technological devices requires the use of express analysis of the generated plasma flux composition. Spectrometric equipment which can be embedded into the technological process to determine the composition of the gas mixture and to analyze the emission spectra of low temperature plasma generated by magnetron sputtering systems and vacuum arc sources is presented. The method of spectral interferometry that allows to control thickness and refractive index of the deposited films with depth from fractions to hundreds of micrometers is described. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Khokhlova M.,Saint Petersburg State University
10th Workshop on Recent Advances in Slavonic Natural Language Processing, RASLAN 2016 - Proceedings | Year: 2016

Since the last decade a number of corpora have become available, a large part of them have been compiled automatically on web data. From traditional text collections such corpora vary both in their volume and content. The paper focuses on the discussion on these corpora and deals with two of them: ruTenTen (18.3 bln tokens) and Araneum Russicum Maximum (13.7 bln tokens). The authors discuss linguistic phenomena across the corpora examining quantitative properties of 20 highfrequency Russian nouns. The lexemes are compared between these corpora and also with data published in the Frequency Dictionary on their rank distributions. This dictionary was compiled on the subset of Russian National Corpus that represents modern Russian of the 20 th century (1950-2007) and can be viewed as an excellent example of a traditional corpus. The analysis shows promising results; there is a close correlation between traditional and web-corpora and this topic should be studied in more detail paying attention to other parts of speech. © Tribun EU 2016.

Sveshnikova S.Iu.,Saint Petersburg State University
CEUR Workshop Proceedings | Year: 2016

Many applied research of geography and oceanology require big data processing. One of these problems it is tsunami waves modeling. This task involves dynamic re-interpolation of bathymetry data on multiple grids of different scales. It is determined by the distance from the coastline and existence of islands along the front of wave. In this work re-interpolation is implemented by applying parallel programming primitives to multidimensional arrays of data, which are distributed across the computer cluster nodes. It allows to work effectively with data that does not fit into the memory of one compute node. In addition to this, it improves processing speed compared to the sequential program. NetCDF format that use for storage bathymetry data it is hierarchical format and he hasn't ready-made solutions for processing in distributed systems. Paper views alternative solutions and use one of these for solve given task. © 2016 Svetlana Iu. Sveshnikova.

Vanin A.A.,Saint Petersburg State University | Brodskaya E.N.,Saint Petersburg State University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2017

The influence of the polarization effects on the local structure and electric double layer near the spherical cationic micelle was studied by molecular dynamics simulations. It was obtained that explicit account of polarizability of micellar solution components does not noticeably change the local structure in the system. Nevertheless, strengthening competition between water molecules and counterions is observed in the nearest proximity to the head groups of a cationic micelle. The counterions tend to penetrate deeper in the micelle corona in the case of explicit account of polarizability but the total number of counterions in the whole micelle corona decreases. It is also accompanied by decrease of water amount in the first hydration shell of the micelle. The contribution of water molecules to the local electric potential is comparable with the contribution of the ions. © 2017 Elsevier B.V.

Chiu H.-C.,University of California at Riverside | Klimchitskaya G.L.,North West Technical University | Marachevsky V.N.,Saint Petersburg State University | Mostepanenko V.M.,Noncommercial Partnership Scientific Instruments | Mohideen U.,University of California at Riverside
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The lateral Casimir force, which arises between aligned sinusoidally corrugated surfaces of a sphere and a plate, was measured for the case of a small corrugation period beyond the applicability region of the proximity force approximation (PFA). The increased amplitudes of the corrugations on both the sphere and the plate allowed observation of an asymmetry of the lateral Casimir force, i.e., deviation of its profile from a perfect sine function. The dependences of the lateral force on the phase shift between the corrugations on both test bodies were measured at different separations in two sets of measurements with different amplitudes of corrugations on the sphere. The maximum magnitude of the lateral force as a function of separation was also measured in two successive experiments. All measurement data were compared with the theoretical approach using the proximity force approximation and with the exact theory based on Rayleigh expansions with no fitting parameters. In both cases real material properties of the test bodies and nonzero temperature were taken into account. The data were found to be in a good agreement with the exact theory but deviate significantly from the predictions of the proximity force approximation approach. This provides the quantitative confirmation for the observation of diffraction-type effects that are disregarded within the PFA approach. Possible applications of the phenomenon of the lateral Casimir force in nanotechnology for the operation of micromachines are discussed. © 2010 The American Physical Society.

Sorokin A.O.,RAS Petersburg Nuclear Physics Institute | Syromyatnikov A.V.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We carry out Monte Carlo simulations to discuss critical properties of a classical two-dimensional XY frustrated helimagnet on a square lattice. We find two successive phase transitions upon the temperature decreasing: the first one is associated with breaking of a discrete Z 2 symmetry and the second one is of the Berezinskii-Kosterlitz-Thouless (BKT) type at which the SO(2) symmetry breaks. Thus, a narrow region exists on the phase diagram between lines of the Ising and the BKT transitions that corresponds to a chiral spin liquid. © 2012 American Physical Society.

Kukushkin V.Yu.,Saint Petersburg State University
Journal of Organic Chemistry | Year: 2010

Chemical Equation Presented 1,3-Dipolar cycloadditions of a series of 12 allyl-anion type 1,3-dipoles X=Y+-Z- (X, Z = CH 2, NH, O.; Y = N(Me), O) to acetonitrile MeC≡N, both free and coordinated to PtII and PtIV in the complexes trans-[PtCln(NCMe)2] (n = 2, 4), were investigated by theoretical methods. The reactivity increases along the following sequence of dipoles, the first three being inert toward nitriles: ON(Me)O < NHN(Me)O < NHN(Me)NH < CH2N(Me)O < OOO ≈ NHONH < CH 2N(Me)NH < NHOO < CH2N(Me)CH2 < CH 2OCH2RSCH2ONH < CH2OO. The thermodynamic stability of the cycloaddition products (reaction energies) inversely correlates with the activation energies with exception of dioxadiazoles N=C(Me)OONH which cannot exist in the uncoordinated state. A complete ortho selectivity of these reactions is predicted. Coordination of MeCN to platinum accelerates the reactions of CH2N(Me)CH2, CH2ONH, and particularly CH2N(Me)O and CH2N(Me)NH and stabilizes the corresponding products. Coordination accelerates the reactions of CH2OCH2, CH2OO, and NHONH only slightly and inhibits the reactions of NHOO and OOO. The cycloadditions of nitrones to nitriles are potentially interesting for dynamic combinatorial chemistry. The details of the reaction mechanisms and correlations of activation and reaction energies, synchronicity, and charge transfer vs dipole nature, FMO energies, atomic charges, HSAB properties, distortion energies, and regioisomeric pathways are discussed. C© 2010 American Chemical Society.

Hutson T.E.,Baylor Sammons Cancer Center | Hutson T.E.,Us Oncology Research | Al-Shukri S.,Saint Petersburg State University | Stus V.P.,Municipal Institution Dnipropetrovsk Regional Clinical Hospital Na Ii Mechnikov | And 7 more authors.
The Lancet Oncology | Year: 2013

Belitsky A.V.,Arizona State University | Manashov A.N.,University of Regensburg | Manashov A.N.,Saint Petersburg State University
Nuclear Physics B | Year: 2014

Scattering amplitudes in maximally supersymmetric gauge theory are dual to super-Wilson loops on null polygonal contours. The operator product expansion for the latter revealed that their dynamics is governed by the evolution of multiparticle GKP excitations. They were shown to emerge from the spectral problem of an underlying open spin chain. In this work we solve this model with the help of the Baxter Q-operator and Sklyanin's Separation of Variables methods. We provide an explicit construction for eigenfunctions and eigenvalues of GKP excitations. We demonstrate how the former define the so-called multiparticle hexagon transitions in super-Wilson loops and prove their factorized form at leading order of 't Hooft coupling for particle number-preserving transitions that were suggested earlier in a generic case. © 2014 The Authors.

Rebyakova V.,Saint Petersburg State University | Strikman M.,Pennsylvania State University | Zhalov M.,RAS Petersburg Nuclear Physics Institute
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We present predictions for the J/ψ and ρ meson production in the heavy ion ultraperipheral collisions (UPC) for the current energy 2.76 TeV at the LHC. Both total cross sections and cross sections with the neutron emission from one or both nuclei are presented. We also perform analysis of the RHIC ρ meson photoproduction data and emphasize importance of these data for testing the current model for nucleus breakup in the UPC. © 2012 Elsevier B.V.

Litvinova E.,Helmholtz Center for Heavy Ion Research | Litvinova E.,Goethe University Frankfurt | Litvinova E.,RAS Institute of Physics and Power Engineering | Ring P.,TU Munich | Tselyaev V.,Saint Petersburg State University
Physical Review Letters | Year: 2010

A new class of many-body models, based on covariant density functional theory for excited states, is presented. It allows a parameter free description of the fragmentation of nuclear states induced by mode coupling of two-quasiparticle and two-phonon configurations. As compared to earlier methods it provides a consistent and parameter free theory of the fine structure of nuclear resonances. The method is applied very successfully to investigate the newly discovered low-lying dipole excitations in Sn and Ni isotopes with large neutron excess. © 2010 The American Physical Society.

Bisnovatyi-Kogan G.S.,National Research Nuclear University | Ikhsanov N.R.,Saint Petersburg State University
Astronomy Reports | Year: 2014

We explore the possibility of explaining Anomalous X-ray Pulsars (AXPs) and Soft Gammaray Repeaters (SGRs) in a scenario with fall-back magnetic accretion onto a young isolated neutron star. The X-ray emission of the pulsar in this case originates due to the accretion of matter onto the surface of the neutron star from a magnetic slab surrounding its magnetosphere. The spin-down rate of the neutron star expected in this picture is close to the observed value. We show that such neutron stars are relatively young and are going through the transition from the propeller state to the accretor state. The pulsar's activity in gamma-rays is connected with its relative youth, and is enabled by energy stored in a non-equilibrium layer located in the crust of the low-mass neutron star. This energy can be released due to the mixing of matter in the neutron star crust with super heavy nuclei approaching its surface and becoming unstable. The fission of nuclei in the low-density region initiates chain reactions leading to a nuclear explosion. Outbursts are probably triggered by instability developing in the region where the matter accreted by the neutron star accumulates in the magnetic polar regions. © 2014 Pleiades Publishing, Ltd.

Sizanov A.V.,RAS Petersburg Nuclear Physics Institute | Syromyatnikov A.V.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We introduce a representation of an integer spin S via bosonic operators which is useful in describing the paramagnetic phase and transitions to magnetically ordered phases in magnetic systems with large single-ion easy-plane anisotropy D. Considering the exchange interaction between spins as a perturbation and using the diagram technique we derive the elementary excitation spectrum and the ground-state energy in the third order of the perturbation theory. In the special case of S=1 we obtain these expressions also using simpler spin representations some of which were introduced before. Comparison with results of previous numerical studies of 2D systems with S=1 demonstrates that our approach works better than other analytical methods applied before for such systems. We apply our results for the elementary excitation spectrum analysis obtained experimentally in NiCl2-4SC(NH2)2 (DTN). It is demonstrated that a set of model parameters (exchange constants and D) which has been used for DTN so far describes badly the experimentally obtained spectrum. A different set of parameters is proposed, using which we fit the spectrum and values of two critical fields of DTN. © 2011 American Physical Society.

Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: HEALTH.2010.2.1.2-3 | Award Amount: 3.88M | Year: 2010

SYSPATHO focuses on the development of novel and generally applicable mathematical methods and algorithms for systems biology. These methods and algorithms will be applied to study the complex interactions of hepatitis C virus (HCV), a human-pathogenic virus of high medical relevance, with its host at the systems level. Using a multidisciplinary, integrative approach, PATHOSYS will (a) develop methods to analyze and integrate a wide variety of data from wet lab experiments, databases and biological literature, (b) develop and apply machine learning tools to reconstruct and study intracellular interaction networks from experimental data, (c) develop new and improve existing algorithms and mathematical methods for bottom-up modelling, to fit models to data, and to analyze the dynamic behaviour of models (d) generate new experimental data to gain novel insights into hepatitis C virus host interactions, and (e) use the newly developed methods and data to model and analyze HCV-host interactions at the systems level. Guided by biological data, PATHOSYS focuses on the design of novel algorithms and mathematical methods for systems biology, with the aim to provide generally applicable tools to elucidate biological processes. Based on developed models and using systems analysis, PATHOSYS will elucidate virus host interactions of Hepatitis C virus at an unprecedented level. As a direct spin-off, models and analysis methods developed in PATHOSYS will lead to the identification of new candidate host cell target genes applicable for the design of novel anti-viral drugs against hepatitis C. Targeting of host cell factors will reduce the likelihood for the development of therapy resistance and increase the chance for broad-spectrum antivirals. Inclusion of two SME partners will ensure exploitation of results generated in PATHOSYS and their transfer into industrial and pharmaceutical applications, thus strengthening economy and health care system in Europe.

Grant
Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2013-ITN | Award Amount: 3.57M | Year: 2013

PRIMO (Power and Regions in a Multipolar World) starts from the premise that the importance of non-western regions and certain of their leading states notably Brazil, Russia, India, China and South Africa, the so-called BRICS states for international politics and the world economy is rapidly growing. However, the nature of these processes, the consequences for global governance, and the material and social power dynamics of BRICS states rise vis--vis international institutions and powers such as the EU and the US are far from clear. There has been a lack of specification and in-depth empirical investigation. Therefore, PRIMO studies the actions, relations, processes and mechanisms of BRICS states interactions, both in their own regions and with well-established powers, multilateral institutions and non-state actors. We combine theoretical approaches, a rigorous mixed research methodology, practical training, and the acquisition of substantial empirical expertise on regional and emerging powers with concrete practical career opportunities in academia or the private sector. PRIMO will allow to account for processes of identity construction, the formation of foreign policy goals, and the strategies of regional powers at the regional and global level. To accomplish these goals, PRIMO establishes a network of public and private partners that will substantially advance and expand already existing structures and collaboration by directing training towards employment opportunities in the private sector, enhancing the mobility of PhD students in and beyond Europe, and advancing the interests of a European research community in a global context.

Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: SPA.2010.3.2-04 | Award Amount: 674.78K | Year: 2011

The trend towards Operationally Responsive Space, where spacecraft can be rapidly assembled, configured and deployed, to meet specific mission needs, e.g. disaster support, requires flexible on board communication networks with plug-and-play capability. The growing autonomy of scientific missions to remote planets requires networks that are robust and durable, able to recover from transitory errors and faults automatically. The importance of spacecraft mass reduction motivates the sharing of networks for payload data-handling and avionics. Avionics and robotics impose requirements on network responsiveness and determinism. Increasing international collaboration on scientific and Earth observation spacecraft requires standard network technology where a component developed by one nation will interoperate effectively with equipment developed by another. SpaceWire-RT aims to fulfil these demanding requirements with a flexible, robust, responsive, deterministic and durable standard network technology that is able to support both avionics and payload data-handling applications. SpaceWire is a very successful first step in this direction, providing networking technology for payload data-handling on over 30 major space missions. It falls short, however, of the requirements for avionics systems. A quality of service (QoS) layer is needed for SpaceWire to support mixed avionics and data-handling applications. SpaceWire-RT will: use virtual channels to provide a variety of QoS; provide broadcast and multicast capability; support extremely low latency time and out-of band signalling; and incorporate novel fault detection, isolation and recovery methods. The network will be fully responsible for information transfer, decoupling application and data transfer. Creation of this technology will substantially strengthen collaborative bonds between the Russian and European organisations involved in the research, and lead to technology of vital importance for future space mission.

Grant
Agency: European Commission | Branch: FP7 | Program: CP-IP-SICA | Phase: ENV.2010.4.1.3-2 | Award Amount: 9.15M | Year: 2010

The overall goal of the proposed project is to develop a coordinated global observation system for mercury able to provide temporal and spatial distributions of mercury concentrations in ambient air and precipitation over land and over surface waters at different altitudes and latitudes around the world. This will then provide high quality data for the validation and application of regional and global scale atmospheric models, to give to governments, national and international organisations and stakeholders a firm basis for future policy development and implementation. Specific objectives of the proposed project are (a) to establish a Global Observation System for Mercury (GMOS) able to provide ambient concentrations and deposition fluxes of mercury species around the world, by combining observations from permanent ground-based stations, and from oceanographic and tropospheric measurement campaigns; (b) to validate regional and global scale atmospheric mercury modelling systems able to predict temporal variations and spatial distributions of atmospheric mercury entering to and re-emitted from terrestrial and aquatic receptors; (c) to evaluate and identify source-receptor relationships at country scale and their temporal trends for current and projected scenarios of mercury emissions from anthropogenic and natural sources; (d) to develop interoperable tools to allow the sharing of observational and models output data produced by GMOS. The overarching goal of GMOS is to support the achievement of goals set by the GEO / GEOSS, and specifically of the GEO Task HE-09-02d and contribute to the advancement of our scientific understanding in the nine Societal Benefit Areas (SBA) established in GEOSS. The proposed project will rely on the results and knowledge acquired in the framework of past EU projects (i.e., MAMCS, MOE, MERCYMS) and international programs (i.e., UNECE TF HTAP; UNEP F&T partnership area).

Grant
Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: ENV.2008.4.1.4.1. | Award Amount: 8.01M | Year: 2009

The Black Sea Catchment is internationally known as one of ecologically unsustainable development and inadequate resource management, which has led to severe environmental, social and economic problems. EnviroGRIDS @ Black Sea Catchment aims at building the capacities of regional stakeholders to use new international standards to gather, store, distribute, analyze, visualize and disseminate crucial information on past, present and future states of the environment, in order to assess its sustainability and vulnerability. The EnviroGRIDS @ Black Sea Catchment project addresses these issues by bringing several emerging information technologies that are revolutionizing the way we are able to observe our planet. The Group on Earth Observation Systems of Systems (GEOSS) is building a data-driven view of our planet that feeds into models and scenarios. EnviroGRIDS aims at building the capacity of scientist to assemble such a system in the Black Sea Catchment, the capacity of decision-makers to use it, and the capacity of the general public to understand the important environmental, social and economic issues at stake. To achieve its objectives, EnviroGRIDS will build an ultra-modern Grid enabled Spatial Data Infrastructure (GSDI) that will become one component in the Global Earth Observation System of Systems (GEOSS), compatible with the new EU directive on Infrastructure for Spatial Information in the European Union (INSPIRE). EnviroGRIDS will particularly target the needs of the Black Sea Commission (BSC) and the International Commission for the Protection of the Danube River (ICPDR) in order to help bridging the gap between science and policy.

News Article | November 18, 2016

An international team of computer scientists has for the first time developed a method to find antibiotics hidden in huge but still unexplored mass spectrometry datasets. They detailed their new method, called DEREPLICATOR, in the Oct. 31 issue of Nature Chemical Biology. Each year more than 2 million people develop antibiotic resistance in the United States, and researchers hope their work will help identify new antibiotics to effectively treat diseases. "This is the first time that we are using Big Data to look into microbial chemistry and characterize antibiotics and other drug candidates," said Hosein Mohimani, a computer scientist at the University of California San Diego and the paper's first author. "Although proteomics researchers have been routinely using huge spectral datasets to find important peptides, all traditional proteomics tools fail when it comes to new drug discovery. " The algorithms the researchers developed scour mass-spectrometry data to discover so-called peptidic natural products (PNPs)--widely used bioactive compounds that include many antibiotics. Mass spectrometry allows researchers to identify the chemical structure of a substance by separating its ions according to their mass and charge. By running mass spectrometry data against a database of chemical structures of known antibiotics, the researchers were able to detect known compounds in substances that had never been analyzed before. This is the first time that this kind of Big Data analysis was possible. The researchers were able to get around the well-known issue of false positives by using statistical analysis to determine the significance of each match between spectra and the antibiotics database. "We got the idea from particle physics," Mohimani said. Researchers used a statistical approach called the Markov Chain Monte Carlo to compute the probability of rare events and to throw false positives out. Researchers also were able to discover new variants of known antibiotics. They did that by first predicting the fragmentation pattern of a chemical structure by using chemical expertise and machine learning. They compared these predictions against experimental data and looked for patterns. This problem resembles guessing the meaning of a sentence in a foreign language by recognizing a few of the words. Researchers have made breakthroughs recently in antibiotics discovery, but PNPs have remained difficult to find. That's because they're more complex than most peptides and built from hundreds of non-standard amino acids, rather than the standard 20. As a result, standard peptide identification tools, such as SEQUEST (the workhorse of modern proteomics) do not work to identify PNPs. The recent launch of the Global Natural Product Social (GNPS) molecular network in 2015 brought together over a hundred laboratories that have already generated an unprecedented amount of mass spectra including antibiotics. But to go from PNP discovery in an academic setting to a high-throughput technology, new algorithms for antibiotics discovery are needed. Indeed, although spectra in the GNPS molecular network represent a gold mine for future discoveries, their interpretation remains a bottleneck. The network was developed by Nuno Bandeira, a computer science professor at the Jacobs School of Engineering and study co-author Pieter Dorrestein, a professor in the UC San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences. Antibiotics researchers use dereplication strategies that identify known PNPs and discover their still unknown variants by comparing billions of spectra with a database of all known PNPs. DEREPLICATOR promises to turn into an equivalent of SEQUEST for antibiotics discovery and, similarly to SEQUEST, enable high-throughput PNP identification. Even in the first application, it identified an order of magnitude more PNPs than any previous dereplication efforts. The study was made possible by the bioinformatics expertise in the research group of Professor Pavel Pevzner, in the Department of Computer Science and Engineering at UC San Diego who developed viable methods to sequence bacteria and metagenomes. They are now adapting these methods to discover the metabolites they produce. In collaboration with Anton Korobeynikov and Alexander Shlemov at Saint Petersburg State University, the researchers are planning to speed up the method and apply it for discovering novel antibiotics from metagenomes. This research relies on computing infrastructure provided by the NIH Center for Computational Mass Spectrometry at UC San Diego. The Mass Spectrometry Innovation Center at UC San Diego, St. Petersburg State University and The University of Tokyo also took part in the research. The work was funded partially by the National Institutes of Health and the Russian Science Foundation. Dereplication of peptidic natural products through database search of mass spectra

Grant
Agency: European Commission | Branch: FP7 | Program: CSA | Phase: ICT-2009.3.2 | Award Amount: 520.84K | Year: 2009

Russia is one of a few countries in the world to have in depth knowledge and capabilities spanning research, design and production of microelectronics and integrated circuits. Despite these strengths, there were no Russian semiconductor organisations participating in FP6 IST. Meanwhile, EU faces challenges in addressing the research priorities for semiconductor design methods and tools identified in the FP7 ICT WP and ENIAC SRA. This situation offers a favourable opportunity for strategic collaboration in semiconductor design between Russia and EU Consequently, the main aim of the SEMIDEC project is to increase cooperation in developing semiconductor design methods and tools between the two regions. SEMIDEC will achieve its overall aim via a range of activities implemented over 24 months: 1) Assessment of the semiconductor design collaboration potential. This involves mapping Russian semiconductor organisations involved in research relevant to the EUs priorities concerning semiconductor design methods, tools and standardisation. It also involves producing a Report on organisations and research on semiconductor design methods and tools in Russia; 2) Organisation of combined awareness-raising/training/networking events in Russia about semiconductor design calls from FP7 ICT WP. Inviting key EU semiconductor organisations to attend who are open to collaboration with Russian counterparts. Also, inviting Russian experts to attend key semiconductor events in EU and examining potential for Russia to participate in ENIAC. Also, producing a good practice guide to participation in FP7 semiconductor components/electronic system projects in Russian; and 3) Provide hands-on support services to competent Russian semiconductor organisations to build long-term relationships with key EU counterparts. Central to this will be i) support to joining EU consortia preparing FP7 ICT proposals and ii) support to Russian researchers to make secondments at EU organisations.

Khlebnikov A.F.,Saint Petersburg State University | Golovkina M.V.,Saint Petersburg State University | Novikov M.S.,Saint Petersburg State University | Yufit D.S.,Durham University
Organic Letters | Year: 2012

A flexible approach to unknown 1-(1H-pyrrol-3-yl)pyridinium salts with selective control of the substitution patterns, by the reaction of pyridinium ylides with 2H-azirines, is disclosed. 3-(Pyridinium-1-yl)pyrrolides, a new type of stable ylide, were prepared from these salts in high yields by treatment with base. Atmospheric-pressure hydrogenation of the ylides with Adams' catalyst lead to 1-(pyrrol-3-yl)piperidines in good yields. © 2012 American Chemical Society.

Malyshev A.V.,Complutense University of Madrid | Malyshev A.V.,Zernike Institute for Advanced Materials | Malyshev V.A.,Zernike Institute for Advanced Materials | Malyshev V.A.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Optical response of an artificial composite nanodimer comprising a semiconductor quantum dot and a metal nanosphere is analyzed theoretically. We show that internal degrees of freedom of the system can manifest bistability and optical hysteresis as functions of the incident field intensity. We argue that these effects can be observed for real-world systems, such as a CdSe quantum dot and an Au nanoparticle hybrid. These properties can be revealed by measuring the optical hysteresis of Rayleigh scattering. We also show that the total dipole moment of the system can be switched abruptly between its two stable states by small changes in the excitation intensity. The latter promises various applications in the field of all-optical processing at the nanoscale, the most basic of them being the volatile optical memory. © 2011 American Physical Society.

Safonova Y.,Saint Petersburg State University | Lapidus A.,Saint Petersburg State University | Lill J.,Genentech
Bioinformatics | Year: 2015

Motivation: The recent introduction of next-generation sequencing technologies to antibody studies have resulted in a growing number of immunoinformatics tools for antibody repertoire analysis. However, benchmarking these newly emerging tools remains problematic since the gold standard datasets that are needed to validate these tools are typically not available. Results: Since simulating antibody repertoires is often the only feasible way to benchmark new immunoinformatics tools, we developed the IgSimulator tool that addresses various complications in generating realistic antibody repertoires. IgSimulator's code has modular structure and can be easily adapted to new requirements to simulation. © The Author 2015.

Ioffe M.V.,Saint Petersburg State University | Krupitskaya E.V.,Akaki Tsereteli State University | Nishnianidze D.N.,Akaki Tsereteli State University
Annals of Physics | Year: 2012

A new two-dimensional quantum model-a generalization of Scarf II-is completely solved analytically for integer values of the parameter. This model not being amenable to the conventional procedure of separation of variables is solved by a recently proposed method of supersymmetrical separation. The latter is based on two constituents of SUSY Quantum Mechanics: the intertwining relations with second order supercharges and the property of shape invariance. As a result, all energies of bound states were found, and the analytical expressions for corresponding wave functions were obtained. © 2011 Elsevier Inc..

Marchenko D.,Helmholtz Center Berlin | Varykhalov A.,Helmholtz Center Berlin | Scholz M.R.,Helmholtz Center Berlin | Bihlmayer G.,Jülich Research Center | And 4 more authors.
Nature Communications | Year: 2012

Graphene in spintronics is predominantly considered for spin current leads of high performance due to weak intrinsic spin-orbit coupling of the graphene π electrons. Externally induced large spin-orbit coupling opens the possibility of using graphene in active elements of spintronic devices such as the Das-Datta spin field-effect transistor. Here we show that Au intercalation at the graphene-Ni interface creates a giant spin-orbit splitting (∼100 meV) of the graphene Dirac cone up to the Fermi energy. Photoelectron spectroscopy reveals the hybridization with Au 5d states as the source for this giant splitting. An ab initio model of the system shows a Rashba-split spectrum around the Dirac point of graphene. A sharp graphene-Au interface at the equilibrium distance accounts for only ∼10 meV spin-orbit splitting and enhancement is due to the Au atoms in the hollow position that get closer to graphene and do not break the sublattice symmetry. © 2012 Macmillan Publishers Limited. All rights reserved.

Dvinskikh S.V.,KTH Royal Institute of Technology | Dvinskikh S.V.,Saint Petersburg State University
Applied Magnetic Resonance | Year: 2013

Pulsed-field-gradient nuclear magnetic resonance (NMR) combined with magic echo decoupling is applied to study anisotropic diffusion in samples with strong static dipolar spin interactions. The approach, due to its moderate demands on the NMR hardware, can be implemented on standard commercial equipment for routine diffusion studies of liquid crystals. Using a microimaging probe, measurement of diffusion in arbitrary spatial direction is possible. Hence, the principal components of the diffusion tensor are directly obtained. Anisotropic diffusion is investigated in the thermotropic mesophases of a homologous series of nOCB liquid crystals and an analogous compound with hydroxyl groups. The geometric average diffusion coefficient changes continuously at the isotropic-nematic phase transition. Experimental data are described in terms of the molecular translation models in the nematic phase and for the second-order nematic-smectic A phase transition. The diffusion anisotropy is higher for the sample with terminal hydroxyl groups suggesting significant molecular association via hydrogen bonding. © 2012 Springer-Verlag.

Karakovskiy S.,Saint Petersburg State University | Togelius J.,IT University of Copenhagen
IEEE Transactions on Computational Intelligence and AI in Games | Year: 2012

This paper describes the Mario AI benchmark, a game-based benchmark for reinforcement learning algorithms and game AI techniques developed by the authors. The benchmark is based on a public domain clone of Nintendo's classic platform game Super Mario Bros, and completely open source. During the last two years, the benchmark has been used in a number of competitions associated with international conferences, and researchers and students from around the world have contributed diverse solutions to try to beat the benchmark. The paper summarizes these contributions, gives an overview of the state of the art in Mario-playing AIs, and chronicles the development of the benchmark. This paper is intended as the definitive point of reference for those using the benchmark for research or teaching. © 2009 IEEE.

Bobrova D.,Saint Petersburg State University
Procedia Engineering | Year: 2015

Today, the use of wind energy is becoming one of the most developed areas of alternative energy. Introduction of means of alternative power engineering in structure of the building demands special events on safety measures that is strongly reflected in space-planning decisions. Increase of energy efficiency of system of the power active building, as a rule, depends on a form of its material and constructive structure. Thus, speaking about integration of means of alternative power engineering into structure of the building, we mean special approach to an architectural shaping. Efforts of architects and engineers are directed on that having united ideas of use of energy of renewable sources, function of the building and art of creation of an architectural form, to receive harmonious result. Search is directed on a choice of forms and designs, not only elements, but also actually buildings which promote increase in amount of the transformed energy. © 2015 Published by Elsevier Ltd.

Zhou X.-Z.,University of California at Los Angeles | Angelopoulos V.,University of California at Los Angeles | Sergeev V.A.,Saint Petersburg State University | Runov A.,University of California at Los Angeles
Journal of Geophysical Research: Space Physics | Year: 2010

We report on the evolving ion distributions associated with the arrival of an earthward propagating dipolarization front in the near-Earth magnetotail using Time History of Events and Macroscale Interactions during Substorms (THEMIS). Ion distributions exhibit steady duskward anisotropy well before the front arrival, suggesting thin current sheet formation at ∼11 RE, during the growth phase of a moderate geomagnetic substorm. As the dipolarization front moves closer, an additional, earthward streaming ion population appears, resulting in an earthward velocity moment. This population eventually overwhelms the preexisting duskward anisotropy and merges with the earthward convecting bulk flow once the dipolarization front arrives. Test-particle simulations show that the observed ion evolution is consistent with a picture of ions reflected and accelerated by the approaching front and moving ahead of it. Copyright 2010 by the American Geophysical Union.

Zolotova N.V.,Saint Petersburg State University | Ponyavin D.I.,Saint Petersburg State University
Journal of Geophysical Research: Space Physics | Year: 2014

The sunspot numbers and polar faculae are analyzed to demonstrate that the current solar activity is close to the Grand minimum. Notably protracted Cycle 23 is found to be similar to the cycles on the eve of the Dalton and Gleissberg-Gnevyshev minima. The polar faculae as proxy of the polar field replicate variations of the sunspot cycle amplitude over the last 100 years. The weak sunspot activity of Cycle 24 is assumed to result in the weak polar field. Key Points Activity cycles preceding the Grand minima tend to be prolonged The polar faculae correlate better with preceding cycle, than next one The budget of activity cycle is lost in annihilation of old polar field ©2014. American Geophysical Union. All Rights Reserved.

Krivovichev S.V.,Saint Petersburg State University
Zeitschrift fur Kristallographie | Year: 2012

Relationships between the ro and b bond-valence parameters are investigated for ideal and distorted coordination polyhedra. For some ranges of the b values, this relationship can be approximated by linear functions, which are used to derive bond-valence parameters for some cationoxygen pairs (ro, b [Å]): Cu2 +-O (1.679, 0.36), Pb2 +-O (1.963, 0.49), Hg2 +-O (1.924, 0.38), Bi3 +-O (1.990, 0.48), Sb3 +-O (1.885, 0.53), Y3 +-O (2.028, 0.35), La3 +-O (2.086, 0.45), Nd3 +-O (2.021, 0.46). © by Oldenbourg Wissenschaftsverlag, München.

Obi T.,Waseda University | Ishmatova D.,Saint Petersburg State University | Iwasaki N.,Waseda University
International Journal of Medical Informatics | Year: 2013

Objective: The paper aims to explore effective measures and strategies for the promotion of ICT-enabled innovations for the elderly and people with special needs. Methods: The paper begins by reviewing current government initiatives in the field of e-health and accessibility that are addressing challenges faced by Japan's rapidly ageing society. It then evaluates the results of Japanese government efforts in the promotion of ICT solutions for its older population against the availability of special infrastructure, device interfaces, and services and applications that meet five essential needs of the elderly with regard to quality of life in highly developed countries. Results and conclusion: The results of the study suggest that more efforts are needed to exploit ICT to transform all domains of society in order to meet the challenges produced by a rapidly ageing population. For that purpose the paper proposes 12 main areas in which to facilitate ICT innovations for an ageing population. It then outlines a number of strategic directions for the formulation of specific measures that will place Japan in the forefront of societal transformation. © 2012 Elsevier Ireland Ltd.

Lukin V.V.,Arctic and Antarctic Research Institute | Vasiliev N.I.,Saint Petersburg State University
Annals of Glaciology | Year: 2014

This paper considers the state of the deep ice borehole 5G at the Russian Antarctic Vostok station after penetration to the surface water of Vostok Subglacial Lake. It discusses the peculiar features of drilling the 'fresh frozen' lake water that has risen in the borehole and the technology for subsequent study of the lake water layer via borehole 5G filled with a kerosene-Freon®mixture. The extremely high rise of lake water via the borehole is attributed to a hydraulic fracture at the side of the borehole, which diverted a large amount of drilling fluid. The proposed technology for the study of the water layer envisages minimal environmental impact and excludes penetration of any of the kerosene-Freon1 mixture to the water layer. This technology has been presented several times at different international forums. There was no critical comment on the Environmental Impact Assessment of the technology at the 37th Antarctic Treaty Consultative Meeting in 2014 and it was adopted for implementation.

Bekryaev R.V.,Saint Petersburg State University | Polyakov I.V.,University of Alaska Fairbanks | Alexeev V.A.,University of Alaska Fairbanks
Journal of Climate | Year: 2010

This study uses an extensive dataset of monthly surface air temperature (SAT) records (including previously unutilized) from high-latitude (>60°N) meteorological land stations. Most records have been updated by very recent observations (up to December 2008). Using these data, a high-latitude warming rate of 1.36°C century -1 is documented for 1875-2008-the trend is almost 2 times stronger than the Northern Hemisphere trend (0.79°C century -1), with an accelerated warming rate in the most recent decade (1.35°C decade -1). Stronger warming in high-latitude regions is a manifestation of polar amplification (PA). Changes in SAT suggest two spatial scales of PA-hemispheric and local. A new stable statistical measure of PA linking high-latitude and hemispheric temperature anomalies via a regression relationship is proposed. For 1875-2008, this measure yields PA of ~1.62. Local PA related to the ice-albedo feedback mechanisms is autumnal and coastal, extending several hundred kilometers inland. Heat budget estimates suggest that a recent reduction of arctic ice and anomalously high SATs cannot be explained by ice-albedo feedback mechanisms alone, and the role of large-scale mechanisms of PA of global warming should not be overlooked. © 2010 American Meteorological Society.

Bankevich A.,Saint Petersburg State University | Pevzner P.A.,University of California at San Diego
Nature Methods | Year: 2016

The recently introduced TruSeq synthetic long read (TSLR) technology generates long and accurate virtual reads from an assembly of barcoded pools of short reads. The TSLR method provides an attractive alternative to existing sequencing platforms that generate long but inaccurate reads. We describe the truSPAdes algorithm (http://bioinf.spbau.ru/spades) for TSLR assembly and show that it results in a dramatic improvement in the quality of metagenomics assemblies. © 2016 Nature America, Inc.

Russian Journal of Nondestructive Testing | Year: 2010

Combinations of electroconductive nonferromagnetic coatings and electroconductive nonferromagnetic bases that are used in industry are analyzed. These are divided into five groups depending on the ratios of their electric conductivities. The scheme, design, and principles of operation of eddy-current frequency transducers are considered. The main dependences for determining their parameters (operating frequency, diameter of the winding, sensitivity to the informative parameter, and interfering factors, etc.) are presented. Examples of measurement problems and the optimal application of this method and the achieved metrological characteristics of compact transducers are presented. © Pleiades Publishing, Ltd., 2010.

Simakov S.K.,Saint Petersburg State University
Journal of Materials Research | Year: 2010

The model of nanosized diamond particles formation at metastable P-T parameters from a C-H-O fluid system is presented. It explains the hydrothermal formation and growth of diamond and the specifics of chemical vapor deposition (CVD) diamond synthesis gas mixtures at low P-T parameters. Further, the model explains the genesis of interstellar nanodiamond formations in space and the genesis of metamorphic microdiamonds in shallow depth Earth rocks. In contrast to models where many possible reactions are considered, the present model makes the simplest possible assumptions about the key processes, and is then able to account for various tendencies seen in experimental data. © 2010 Materials Research Society.

Dementyev A.V.,Saint Petersburg State University
New Astronomy | Year: 2015

Nemilov S.V.,Saint Petersburg State University
Glass Physics and Chemistry | Year: 2010

A brief review is presented of the concepts regarding the nature of α and β relaxation processes in melts and glasses. Experimental data have been used to show that different types of relaxation in oxide systems can be interrelated to each other. The molecular mechanism of viscous flow in inorganic systems has been discussed in detail with the use of continuum theories (elasticity and hydrodynamics) developed in the works by the author in 1967-2007. A rigorous relationship between the volumes of atoms overcoming the activation barrier, the instantaneous shear modulus, and the barrier itself (free activation energy) has been derived. This relationship allows one to calculate the sizes of atoms involved in the viscous flow with a deviation that does not exceed 10% of the values determined by direct structural methods. In this case, empirically chosen con- stants are absent. Based on the results obtained by Anderson and Stewart (1954) and the author (1974), it has been established that the activation energy for ionic conduction can be calculated using similar notions. It has been demonstrated for the first time that the universal relation between the viscosity and conductivity over a wide range of temperatures (for alkali-containing oxide melts) i.e., the Littleton equation, finds a simple quantitative explanation in the framework of the same models, even though the mechanisms of both processes do not depend on each other. © Pleiades Publishing, Ltd., 2010.

Utkin L.V.,Saint Petersburg State University | Zhuk Y.A.,Saint Petersburg State University
Knowledge-Based Systems | Year: 2014

Robust classification models based on the ensemble methodology are proposed in the paper. The main feature of the models is that the precise vector of weights assigned for examples in the training set at each iteration of boosting is replaced by a local convex set of weight vectors. The minimax strategy is used for building weak classifiers at each iteration. The local sets of weights are constructed by means of imprecise statistical models. The proposed models are called RILBoost (Robust Imprecise Local Boost). Numerical experiments with real data show that the proposed models outperform the standard AdaBoost algorithm for several well-known data sets. © 2014 Elsevier B.V. All rights reserved.

Filatov S.K.,Saint Petersburg State University
Crystallography Reports | Year: 2011

A general concept of the symmetry transformation of a material during its thermal expansion and final polymorphic transition is proposed based on numerous experimental data. Within this concept, the atomic nature of the transformation of the crystal structure with a change in temperature is considered. Particular attention is paid to the thermal expansion of materials, along with the well-known tendency of a thermally induced increase in the crystal symmetry, which is generally considered to be the directionality of material transformation during polymorphic transitions. © Pleiades Publishing, Inc., 2011.

Heberger K.,Hungarian Academy of Sciences | Zenkevich I.G.,Saint Petersburg State University
Journal of Chromatography A | Year: 2010

The comparison of different polarity measures (parameters, descriptors, variables, scales, etc.) indicates that evaluation of interrelations between these measures is important for better understanding and interpretation of chemical and/or analytical data, especially for chromatographic separation. The best linear correlation between gas chromatographic and non-chromatographic polarity descriptors is revealed for the first time: this pair of variables is the difference of gas chromatographic retention indices on standard polar and non-polar phases as well as the difference between non-dimensional indices of boiling points (known in chromatography since mid-1980s as dispersion indices) and indices of molar refractions. The correlation helps chromatographers to find preferable chemical variables (features) to understand better the separation phenomena and to find better correlations in QSRR models. Principal component analysis (PCA) of ten frequently applied polarity measures shows their similarity and, at the same time, it shows the absence of anomalies within the set of simple organic molecules. A novel ranking method for ten polarity parameters points out that the two most informative polarity measures are (i) the non-dimensional index for boiling point and (ii) the difference in chromatographic retention indices on standard polar and non-polar stationary phases. On the other hand, the hydrophobicity parameter, log P, sometimes considered as polarity parameter in HPLC seems to be the worst one in description of "polarity" in gas chromatography. Surprisingly, such polarity measures like dipole moment and permittivity used often in organic chemistry does not provide the best correlation with gas chromatographic polarity measures. © 2010 Elsevier B.V.

Valiev F.F.,Saint Petersburg State University
Proceedings of the International Conference Days on Diffraction, DD 2012 | Year: 2012

The results of calculating space-time characteristics of electromagnetic radiation of the superlight source are presented in this paper. The superlight source is formed by free electrons arisen from the lengthy gas target ionization by short pulses of gamma quanta fallen from the strait-line segment. The secondary electromagnetic field generated by this source is calculated using solution of the axially symmetric problem and the superposition principle. © 2012 IEEE.

Tsyganenko N.A.,Saint Petersburg State University | Andreeva V.A.,Saint Petersburg State University
Geophysical Research Letters | Year: 2014

Arridge et al. (2008) reported evidence for the formation of a "bowl-shaped" equatorial current disk in Saturn's magnetosphere during epochs with large planetary dipole tilt angle from perpendicularity with the Sun-planet axis. Using a large multiyear set of Geotail, Polar, and Time History of Events and Macroscale Interactions spacecraft data and a simple model of the magnetic field reversal surface, we found that a similar kind of the tilt-related magnetic field deformation is present in the Earth's magnetosphere. Based on the properties of a tilted vacuum magnetic field configuration, we conclude that the bowl-shaped distortion is a universal feature of magnetospheres with a tilted planetary dipole, resulting from the joint effect of the north-south asymmetry due to the tilt and of the day-night asymmetry imposed by the solar wind flow. Key Points Dayside equatorial current always deflects antisunward from the dipole equator A data-based model of the global magnetospheric deformation is developed The deformation is interpreted in terms of magnetic mirror ratio distribution ©2014. American Geophysical Union. All Rights Reserved.

Syromyatnikov A.V.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We demonstrate that long-range interaction in a system can lead to a very strong interaction between long-wavelength quasiparticles and make them heavily damped. In particular, we discuss magnon spectrum using 1/S expansion in three-dimensional Heisenberg ferromagnet (FM) with arbitrary small dipolar forces at T TC. We obtain that a fraction of long-wavelength magnons with energies k

Bobylev V.V.,Saint Petersburg State University
Astronomy Letters | Year: 2015

VLBI measurements of the absolute proper motions of 23 radio stars have been collected from published data. These are stars with maser emission, or very young stars, or asymptotic-giant-branch stars. By comparing these measurements with the stellar proper motions from the optical catalogs of the Hipparcos Celestial Reference Frame (HCRF), we have found the components of the residual rotation vector of this frame relative to the inertial coordinate system: (ωx, ωy, ωz) = (−0.39, −0.51, −1.25) ± (0.58, 0.57, 0.56) mas yr−1. Based on all the available data, we have determined new values of the components of the residual rotation vector for the optical realization of the HCRF relative to the inertial coordinate system: (ωx, ωy, ωz) = (−0.15, +0.24,−0.53) ± (0.11, 0.10, 0.13) mas yr−1. © 2015, Pleiades Publishing, Inc.

Titov V.,Saint Petersburg State University
Astronomische Nachrichten | Year: 2015

Periodic solutions of the general three-body problem are investigated in the shape space. Two different solutions are considered: the first is an extension of the well-known figure-eight orbit, and the second one is from the free-fall problem. Using the shape space, we reduce the dimension of the problem. These orbits are obtained numerically and described on the Euclidean plane and on the shape sphere. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zvereva G.N.,Saint Petersburg State University
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2010

The electron energy-distribution functions, the rates of plasmochemical reactions, and the densities of various plasma components have been calculated for a microwave discharge (f = 1000 MHz, P = 100-700 mW) in krypton plasma (p = 0.5 atm) excited by an electron beam with an energy of 12 keV. It has been found that the heating by a microwave field shifts the peak of the electron energy-distribution function (EEDF) from 0.5 to 2 eV, which leads to higher rates of reactions with excitation thresholds lying near the EEDF peak. As a result, the population of excited levels increases by two to three times. © 2010 Pleiades Publishing, Ltd.

Polubotko A.M.,RAS Ioffe Physical - Technical Institute | Smirnov V.P.,Saint Petersburg State University
Journal of Raman Spectroscopy | Year: 2012

The expression for the surface-enhanced hyper Raman scattering (SEHRS) cross-section of symmetrical molecules within the framework of the dipole-quadrupole theory is presented. It is formed by contributions that depend on various dipole and quadrupole moments. The enhancement coefficients for the quadrupole enhancement mechanism in some limited cases can reach a value 10 30. It is demonstrated that the contributions follow some selection rules. Qualitative classification of the contributions based on the enhancement degree is given. It is demonstrated that the SEHR spectra of pyrazine and pyridine can be explained by the presented theory. Copyright © 2011 John Wiley & Sons, Ltd.

Krivovichev S.V.,Saint Petersburg State University
Crystallography Reports | Year: 2012

Atomic-molecular mechanisms of crystal growth can be modeled based on crystallochemical information using cellular automata (a particular case of finite deterministic automata). In particular, the formation of heteropolyhedral layered complexes in uranyl selenates can be modeled applying a one-dimensional three-colored cellular automaton. The use of the theory of calculations (in particular, the theory of automata) in crystallography allows one to interpret crystal growth as a computational process (the realization of an algorithm or program with a finite number of steps). © 2012 Pleiades Publishing, Ltd.

Galyamin S.N.,Saint Petersburg State University | Tyukhtin A.V.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We analyze the electromagnetic field of a moving point charge in the presence of a "left-handed" medium (LHM). First, the case of uniform motion of the charge in infinite LHM was considered. Using complex function theory methods, we decomposed the total field into a "quasi-Coulomb" field, a wave field (Cherenkov radiation) and a "plasma trace." In addition, an effective numerical algorithm was developed for the total field computation, and typical plots were presented. It was shown that the wave field in LHM lags behind the charge more so than it does in ordinary medium. Furthermore, we investigated a charge intersecting the interface between vacuumlike medium and LHM. Asymptotic expressions for the field components were obtained and algorithms for their computation were developed. The spatial radiation can be separated into three distinct components, corresponding to ordinary transition radiation with a relatively large magnitude, Cherenkov radiation and reversed Cherenkov-transition radiation (RCTR). Rigorous conditions for generating RCTR were obtained: RCTR in the vacuum area was found to be the double threshold effect in both frequency and charge velocity domain. The RCTR decay in vacuum due to the losses in LHM was studied. Areas of the RCTR significance were determined and were found to be sufficiently large for observation. Possible applications to the beam diagnostics and the characterization of metamaterials were suggested. © 2010 The American Physical Society.

Sunagar K.,University of Porto | Johnson W.E.,U.S. National Cancer Institute | O'Brien S.J.,U.S. National Cancer Institute | O'Brien S.J.,Saint Petersburg State University | And 2 more authors.
Molecular Biology and Evolution | Year: 2012

Cysteine-rich secretory proteins (CRISPs) are glycoproteins found exclusively in vertebrates and have broad diversified functions. They are hypothesized to play important roles in mammalian reproduction and in reptilian venom, where they disrupt homeostasis of the prey through several mechanisms, including among others, blockage of cyclic nucleotide-gated and voltage-gated ion channels and inhibition of smooth muscle contraction. We evaluated the molecular evolution of CRISPs in toxicoferan reptiles at both nucleotide and protein levels relative to their nonvenomous mammalian homologs. We show that the evolution of CRISP gene in these reptiles is significantly influenced by positive selection and in snakes (ω = 3.84) more than in lizards (ω = 2.33), whereas mammalian CRISPs were under strong negative selection (CRISP1 = 0.55, CRISP2 = 0.40, and CRISP3 = 0.68). The use of ancestral sequence reconstruction, mapping of mutations on the three-dimensional structure, and detailed evaluation of selection pressures suggests that the toxicoferan CRISPs underwent accelerated evolution aided by strong positive selection and directional mutagenesis, whereas their mammalian homologs are constrained by negative selection. Gene and protein-level selection analyses identified 41 positively selected sites in snakes and 14 sites in lizards. Most of these sites are located on the molecular surface (nearly 76 in snakes and 79 in lizards), whereas the backbone of the protein retains a highly conserved structural scaffold. Nearly 46 of the positively selected sites occur in the cysteine-rich domain of the protein. This directional mutagenesis, where the hotspots of mutations are found on the molecular surface and functional domains of the protein, acts as a diversifying mechanism for the exquisite biological targeting of CRISPs in toxicoferan reptiles. Finally, our analyses suggest that the evolution of toxicoferan-CRISP venoms might have been influenced by the specific predatory mechanism employed by the organism. CRISPs in Elapidae, which mostly employ neurotoxins, have experienced less positive selection pressure (ω = 2.86) compared with the "nonvenomous" colubrids (ω = 4.10) that rely on grip and constriction to capture the prey, and the Viperidae, a lineage that mostly employs haemotoxins (ω = 4.19). Relatively lower omega estimates in Anguimorph lizards (ω = 2.33) than snakes (ω = 3.84) suggests that lizards probably depend more on pace and powerful jaws for predation than venom. © The Author(s) 2012.

Chernysh S.,Saint Petersburg State University | Kozuharova I.,Russian Academy of Sciences
International Immunopharmacology | Year: 2013

Alloferons are a group of naturally occurring peptides primarily isolated from insects and capable of stimulating mouse and human NK cell cytotoxicity towards cancer cells. In this paper we examined anti-tumor activity of alloferon-1 and its novel structural analog referred to as allostatine. The activity was tested in naïve and preventively tumor antigen vaccinated DBA/2 mice subcutaneously grafted with syngenic P388D1 mouse leukemia cells. In naïve animals allostatine demonstrated tumoristatic activity prevailing over alloferon-1 effect. The preventive vaccination caused only weak tumoristatic effect in 27% of vaccinated animals. The vaccination efficacy was dramatically enhanced by allostatine but not alloferon-1 administration: 65% of allostatine treated animals benefitted from tumoristatic effect and 30% was completely cured so that total number of positive responders grew to 95%. Thus, alloferon-1 and especially allostatine are worthy of further consideration as potential anti-cancer drugs. Allostatine seems to be particularly perspective for adjuvant cancer immunotherapy. Sequence similarity search revealed evolutionary conserved allostatine-like pattern inserted to CDR3 region of human and mouse immunoglobulins. By analogy with allostatine, the pattern may execute some unknown so far function in anti-tumor immune response regulation. © 2013 Elsevier B.V.

Peshkova M.A.,Saint Petersburg State University | Mikhelson K.N.,Saint Petersburg State University
Electrochimica Acta | Year: 2013

A recently introduced tuned galvanostatic mode of measurements with ion-selective electrodes (ISEs) is utilized to perform analytical measurements in the nanomolar concentration range with the same or better selectivity than within the traditional ISE working range. Experimental evidence is provided for Ohmic behavior of ISEs when polarized with relatively large currents. Complete unified protocol of the optimization of the compensating current densities for a given ISE in a given solution is presented, as well as the complete unified protocol of analysis of extremely diluted samples. It is also demonstrated that tuned galvanostatic polarization has beneficial effect on the selectivity of ISEs. The problems related to incomplete relaxation of ISEs when the current is shut off are discussed as well. © 2013 Elsevier Ltd.

Braun M.,Saint Petersburg State University
European Physical Journal C | Year: 2010

It is shown that in the eikonal scattering of a fast quark in the external field loop corrections to the gluon emission amplitude due to virtual softer gluon after renormalization coincide with a correction due to reggeization of the exchanged gluon in the BFKL picture. © © Springer-Verlag / Società Italiana di Fisica 2010.

Yasnov L.V.,Saint Petersburg State University
Solar Physics | Year: 2014

Antonov N.V.,Saint Petersburg State University | Gulitskiy N.M.,Di Mendeleyev Institute For Metrology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

The problem of anomalous scaling in magnetohydrodynamics turbulence is considered within the framework of the kinematic approximation, in the presence of a large-scale background magnetic field. Field theoretic renormalization group methods are applied to the Kazantsev-Kraichnan model of a passive vector advected by the Gaussian velocity field with zero mean and correlation function α δ(t-t′)/k d+ε. Inertial-range anomalous scaling for the tensor pair correlators is established as a consequence of the existence in the corresponding operator product expansions of certain "dangerous" composite operators, whose negative critical dimensions determine the anomalous exponents. The main technical result is the calculation of the anomalous exponents in the order ε 2 of the ε expansion (two-loop approximation). © 2012 Springer-Verlag.

Khryashchev S.M.,Saint Petersburg State University
Nonlinear Phenomena in Complex Systems | Year: 2015

Control systems with a finite number of control parameters (dynamical polysystems) are considered. It is assumed that the control switchings occur at some discrete times. Controllability of the systems is studied. Statistic methods of number theory are applied. Existence of integer control times is established by analysis of Diophantine inequalities. The values of control times can be found by some numerical methods. The statements on controllability are proved. Some examples are considered. © 2015, Education and Upbringing Publishing. All rights reserved.

Shcherbina T.,Saint Petersburg State University
Journal of Mathematical Physics | Year: 2015

We prove that the asymptotic behavior of the second mixed moment of the characteristic polynomials of the N × N 1D Gaussian real symmetric band matrices with the width of the band W ≫ N1/2 coincides with those for the Gaussian orthogonal ensemble. Here, we adapt the approach of Shcherbina [Commun. Math. Phys. 328, 45-82 (2014)], where the Hermitian case was considered. © 2015 AIP Publishing LLC.

Nazarov S.A.,Saint Petersburg State University | Taskinen J.,University of Helsinki
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2015

We construct a family of periodic piezoelectric waveguides Πɛ, depending on a small geometrical parameter, with the following property: as ɛ → +0, the number of gaps in the essential spectrum of the piezoelectricity problem on Πɛ grows unboundedly. © 2015, Springer Basel.

Slavyanov S.Y.,Saint Petersburg State University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2015

A Fuchsian 2 × 2 system generating the Painlevé equation P6 is acted on by a polynomial transformation similar to rotation in order to reduce the polynomial degree of matrices in the left- and the right-hand sides of the system. This clarifies the derivation of the Painlevé equation and the study of its symmetries. © 2015, Pleiades Publishing, Ltd.

Egorov A.V.,Saint Petersburg State University | Lyubartsev A.P.,University of Stockholm | Laaksonen A.,University of Stockholm
Journal of Physical Chemistry B | Year: 2011

To study the effects of water on conformational dynamics of polyalcohols, Molecular Dynamics simulations of glycerol-water liquid mixtures have been carried out at different concentrations: 42.9 and 60.0 wt % of glycerol, respectively. On the basis of the analysis of backbone conformer distributions, it is found that the surrounding water molecules have a large impact on the populations of the glycerol conformers. While the local structure of water in the liquid mixture is surprisingly close to that in pure liquid water, the behavior of glycerols can be divided into three different categories where roughly 25% of them occur in a structure similar to that in pure liquid of glycerol, ca. 25% of them exist as monomers, solvated by water, and the remaining 50% of glycerols in the mixture form H-bonded strings as remains of the glycerol H-bond network. The typical glycerol H-bond network still exists even at the lower concentration of 40 wt % of glycerol. The microheterogeneity of water-glycerol mixtures is analyzed using time-averaged distributions of the sizes of the water aggregates. At 40 wt % of glycerol, the cluster sizes from 3 to 10 water molecules are observed. The increase of glycerol content causes a depletion of clusters leading to smaller 3-5 molecule clusters domination. Translational diffusion coefficients have been calculated to study the dynamical behavior of both glycerol and water molecules. Rotational-reorientational motion is studied both in overall and in selected substructures on the basis of time correlation functions. Characteristic time scales for different motional modes are deduced on the basis of the calculated correlation times. The general conclusion is that the presence of water increases the overall mobility of glycerol, while glycerol slows the mobility of water. © 2011 American Chemical Society.

Evarestov R.A.,Saint Petersburg State University | Bandura A.V.,Saint Petersburg State University
Solid State Ionics | Year: 2011

The different ways of water molecule adsorption were simulated at (001) ZrO2-terminated surfaces of Y-doped BaZrO3 using hybrid HF-DFT method. The water adsorption energies were calculated after the full optimization of atomic positions within the water-slab systems. The proton releasing and hydroxyl group formation was established as result of the exothermic water molecule dissociation. The most favorable proton positions in the surface layers of Y-doped BaZrO3 were specified. To study the proton diffusion from surface to the deeper layers, the energy barriers were estimated for the proton jumping from one oxygen atom to another. © 2010 Elsevier B.V. All rights reserved.

Sokolov A.V.,Saint Petersburg State University
Journal of Physics A: Mathematical and Theoretical | Year: 2015

We study relations describing the intertwining of n × n matrix, in general non-Hermitian, one-dimensional Hamiltonians by matrix linear differential operators with nondegenerate coefficients of in the highest degree. Some methods for constructing matrix intertwining operators of the first order of general form are proposed and their interrelations are examined. We construct, as an example, a 2 × 2 matrix Hamiltonian of general form intertwined by an operator of the first order with the Hamiltonian with zero matrix potential. It is shown that one can add, for the final 2 × 2 matrix Hamiltonian with respect to the initial matrix Hamiltonian, with the help of an intertwining operator of first order, up to two bound states for different energy values, or up to two bound states described by vector-eigenfunctions for the same energy value, or up to two bound states described by a vector-eigenfunction and an associated vector-function for the same energy value. © 2015 IOP Publishing Ltd.

Averianov A.,Saint Petersburg State University | Archibald J.D.,San Diego State University
Canadian Journal of Earth Sciences | Year: 2013

A parsimony analysis of the distribution of 408 characters in 73 taxa of Cretaceous eutherians and related taxa places three species of Paranyctoides, the Asiatic P. quadrans and the North American P. sternbergi and P. maleficus, into a monophyletic taxon supported by three unambiguous synapomorphies. In this analysis P. quadrans has three autapomorphies, but in the analysis using combined terminal taxon for the entire sample of North American Paranyctoides two of these autapomorphies (development of stylar cusps C and D on upper molars) disappeared because these characters are also variably present in the North American sample. The remaining autapomorphy of P. quadrans, m3 shorter than m2, is known from a single specimen and also may be affected by individual variation. The North American sample of Paranyctoides cannot be clearly separated into distinct species on morphological or morphometric grounds and is considered as representing a single species, P. sternbergi Fox, 1979 (= P. maleficus Fox, 1984, syn. nov.). It differs from the Asiatic P. quadrans (Nesov, 1993) only in having a sharp lingual ridge on p5 and m3 longer than m2. Paranyctoides is the sister taxon to Zhelestidae; this clade is supported by four unambiguous synapomorphies.

Reshchikov A.V.,Saint Petersburg State University
Journal of the Entomological Research Society | Year: 2011

Lathrolestes is recorded from Turkey for the first time. Three new species are described and illustrated: Lathrolestes acinaces Reshchikov sp. nov., L. fascialis Reshchikov sp. nov., L. zoticus Reshchikov sp. nov. Lathrolestes citrofrontalis Schmiedeknecht, 1912 is considered as junior synonym with L. ungularis (Thomson, 1883).

Tsyganenko N.A.,Saint Petersburg State University
Journal of Geophysical Research: Space Physics | Year: 2014

The paper presents first results of the data-based modeling of the geomagnetospheric magnetic field, using the data of Polar, Geotail, Cluster, and Time History of Events and Macroscale Interactions during Substorms satellites, taken during the period 1995-2012 and covering 123 storm events with SYM-H ≥ -200 nT. The most important innovations in the model are (1) taking into account the interplanetary magnetic field (IMF)-dependent shape of the model magnetopause, (2) a physically more consistent global deformation of the equatorial current sheet due to the geodipole tilt, (3) symmetric and partial components of the ring current are calculated based on a realistic background magnetic field, instead of a purely dipolar field, used in earlier models, and (4) the validity region on the nightside is extended to ∼40-50 R E. The model field is confined within a magnetopause, based on Lin et al. (2010) empirical model, driven by the dipole tilt angle, solar wind pressure, and IMF Bz. A noteworthy finding is a significant dependence of the magnetotail flux connection across the equatorial plane on the model magnetopause flaring rate, controlled by the southward component of the IMF. Key Points A data-based magnetosphere model with IMF-dependent magnetopause is developed The variable magnetopause flaring affects the magnetotail field stretching Mutually consistent deformations of the equatorial current and the magnetopause ©2014. American Geophysical Union. All Rights Reserved.

Anikiev D.,Saint Petersburg State University | Valenta J.,Czech Institute of Rock Structure And Mechanics | Stanek F.,Czech Institute of Rock Structure And Mechanics | Eisner L.,Czech Institute of Rock Structure And Mechanics
Geophysical Journal International | Year: 2014

Seismic monitoring can greatly benefit from imaging events with a low signal-to-noise ratio (SNR) as the number of the events with a low signal grows exponentially. One way to detect weaker events is improvement of a SNR by migration-type stacking of waveforms from multiple stations. We have developed a new method of location of seismic events that involves stacking of seismic phases and amplitudes along diffraction traveltime curves to suppress noise and detect seismic events with a SNR lower than that on individual receivers. The stacking includes polarity correction based on a simultaneous seismic moment tensor inversion and detection algorithm on the stack function. We applied this method to locate microseismicity induced by hydraulic fracturing. First we calibrated the velocity model by locating perforation shots at known locations. Then we processed 3 d of data from microseismic monitoring of shale stimulation and benchmarked migration-type locations of the largest events that were manually located. The detected and located events induced by hydraulic fracturing in this case study are mostly shear events forming narrow bands along the maximum horizontal stress direction approximately 100 m above the injection intervals. The proposed technique is fully automated and feasible for real-time seismic monitoring. © The Authors 2014.Published by Oxford University Press on behalf of The Royal Astronomical Society.

Cherepanov G.O.,Saint Petersburg State University
Paleontological Journal | Year: 2014

The scute mosaic (pholidosis) in the turtle shell is characterized by two phenomena: phylogenetic stability of the general body plan and wide individual variability. The study of turtle morphogenesis allowed this phenomenon to be explained. It is shown that scute rudiments are formed in embryogeny as local epidermal thickenings, placodes; the positions of placodes is strictly confined to certain parts of the body and their foundation is realized in strict sequence. In particular, in the carapace, placodes are formed exclusively opposite the transverse trunk myosepta, in septal depressions of the embryonic integument; at the same time, marginal placodes are formed in each septal depression (i.e., segment by segment); placodes of pleural and central series are formed in alternate position in the even and odd depressions, respectively. The stability of the scute pattern is connected with the basic mechanisms of morphogenesis, providing the maintenance of bilateral symmetry and determination of scute positions by the primary embryonic segmentation. The main sourse for pholidosis variability is the presence in turtle embryos of vacant septal depressions, in which extraordinary placodes could have developed in the case of minor disturbances of embryogenesis. These aberrations are rather frequent and usually result in asymmetry of the scutation. The breaking of turtle pholidosis symmetry is connected with deviations in ontogenesis, such as asymmetrical formation of epidermal placodes, with a shift to one body side for a segment or more, the formation of additional placodes in the vacant septal depressions, atypical fusion of neighboring epidermal placodes, the absence of regular epidermal placodes in typical body segments. © 2014, Pleiades Publishing, Ltd.

Struts A.V.,University of Arizona | Struts A.V.,Saint Petersburg State University | Salgado G.F.J.,Ecole Normale Superieure de Paris | Martinez-Mayorga K.,Torrey Pines Institute for Molecular Studies | Brown M.F.,University of Arizona
Nature Structural and Molecular Biology | Year: 2011

X-ray and magnetic resonance approaches, though central to studies of G protein-coupled receptor (GPCR)-mediated signaling, cannot address GPCR protein dynamics or plasticity. Here we show that solid-state 2H NMR relaxation elucidates picosecond-to-nanosecond-timescale motions of the retinal ligand that influence larger-scale functional dynamics of rhodopsin in membranes. We propose a multiscale activation mechanism whereby retinal initiates collective helix fluctuations in the meta I-meta II equilibrium on the microsecond-to-millisecond timescale. © 2011 Nature America, Inc. All rights reserved.

Kozynchenko S.A.,Saint Petersburg State University
RuPAC 2012 Contributions to the Proceedings - 23rd Russian Particle Accelerator Conference | Year: 2012

In this paper the program for simulation and optimization of beam dynamics in injection systems is considered, which at the same time allows the choice of parameters of the accelerating-focusing system. This permits designing the injection system during optimization process, taking into account the required output characteristics of the beam. The given program is based on Win 32 API dialog boxes and is developed in standard C++, using parallel programming tools based on the MPI-1. Copyright © 2012 by the respective authors.

Nikiforov K.A.,Saint Petersburg State University | Egorov N.V.,Saint Petersburg State University
RuPAC 2012 Contributions to the Proceedings - 23rd Russian Particle Accelerator Conference | Year: 2012

The program complex in MATLAB intended for vacuum nanoelectronics simulations is described. Physical and mathematical models, computational methods and algorithms of program complex are presented. Electrostatic simulation of electron transport processes is discussed under electron massless approximation; current function method and Matlab PDE Toolbox finite element solutions are used. Developed program complex is able to simulate diode and triode structures with complicated submicron geometry, current-voltage characteristics, calculate electric field distribution, estimate electric line interaction. The modelling results by the example of two different triode structures are presented. Matlab stand-alone application with graphical user interface for demonstration purposes is presented. Copyright © 2012 by the respective authors.

Ivanov A.,Saint Petersburg State University
RuPAC 2012 Contributions to the Proceedings - 23rd Russian Particle Accelerator Conference | Year: 2012

An approach based on matrix formalism for solving differential equations is described. Effective in sense of performance matrix formalism can be tested with less efficient, but accurate traditional algorithm of numerical simulation based on the Runge-Kutta scheme. In both cases the symplectic version of the algorithms are used. The results coincide to analytical calculations, but some disagreements have been identified. The approach implementation is demonstrated in the problem of long-term spin dynamics in electrostatic fields. Copyright © 2012 by the respective authors.

Drivotin O.I.,Saint Petersburg State University
RuPAC 2012 Contributions to the Proceedings - 23rd Russian Particle Accelerator Conference | Year: 2012

The present report deals with degenerate solutions of the Vlasov equation. By degenerate solution we mean a distribution which has a support of dimension smaller than dimension of the phase space. Well known example is the Kapchinsky-Vladimirsky (KV) distribution, when particles are distributed on the 3-dimensional surface in the 4-dimensional phase space. We use covariant formulation of the Vlasov equation developed previously [1]. In traditional approach, the Vlasov equation is considered as integro-differential equation with partial derivatives on phase coordinates. For the covariant formulation of the Vlasov equation, we use such tensor object as the Lie derivative. According to the covariant approach, a degenerate solution is described by differential form which degree is equal to the dimension of its support. Main attention is paid to the KV distribution, which is described by the differential form of the third degree. It is demonstrated that the KV distribution satisfies to the Vlasov equation in covariant formulation. This work has theoretical as well as practical significance. Presented results can be applied for description and simulation of high-intensity beam. Copyright © 2012 by the respective authors.

Sheikin E.G.,Saint Petersburg State University
50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2012

Short review of some results obtained in analysis of MHD-controlled inlets using local MHD effects on supersonic flow is given. Investigations of local MHD effects on supersonic flows in the nonuniform magnetic field made for different positions of locally ionized regions show significant role of both the imposed electric field and the MHD interaction parameter on the flow field. It is shown that the local MHD effect can be used to control the lift-drag ratio, the oblique shock position, to increase the flow compression and to reduce the Mach number. Copyright © 2012 by Sheikin E.G.

Gamayunova O.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The St. Petersburg State Polytechnical University is one of the 15 universities who won in the competition for the right to obtain a grant of Ministry of Education of the Russian Federation in order to enhance their competitiveness among the world's leading research and education centers. The purpose of the Program "5-100-2020" is ensure the entry of at least five Russian universities in the top one hundred world's leading universities by 2020 (according to the QS World University Rankings). The article discusses the role of the Civil Engineering Institute in increasing the international competitiveness of the St. Petersburg State Polytechnical University. © 2015 Published by Elsevier Ltd.

Murgul V.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The paper is dedicated to the creation of the atriums in the historical centre of Saint-Petersburg for improving the quality of courtyards. Since 19 century Saint-Petersburg was built mostly with brick buildings along the perimeter of allotments with founding one or several courtyards. "Well-like" courtyards of historical buildings of Saint-Petersburg have typically a lack of illumination and insolation, are badly ventilated and are often transformed into parking lots for inhabitants. Possibility of glassing of "well-like" courtyards is analyzed from the viewpoint of historical buildings protection regulation of Saint-Petersburg and norms of insolation and illumination of the dwelling buildings, basing on the actual experience in the creation of atriums in Saint-Petersburg. © 2015 Published by Elsevier Ltd.

Strelets K.,Saint Petersburg State University
Procedia Engineering | Year: 2015

One of the most important problems of air purification in the industrial construction industry is setting up a proper efficient airpurification system. There are some methods to evaluate air purification performance, but not all the methods offer such distinct features as turbulence impacts on dust dispersion when settling. Solutions for proper methods to be used have been specified in this article. © 2015 Published by Elsevier Ltd.

Zayats I.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The modern wind-power engineering is one of the perspective directions of using ecological clean energy in the building. The article deals with the historical aspects in the transformation of the windmill's architectural forms, structures and their elements, which intend to convert wind's energy. © 2015 Published by Elsevier Ltd.

Gamayunova O.,Saint Petersburg State University
Procedia Engineering | Year: 2015

Often, the high school students worry about their future profession. Their future life depends on this choice. That is why the decision should be balanced and considered. The article describes the main activities and the means by which the Civil Engineering Institute of the St. Petersburg State Polytechnical University helps applicants to take the first steps towards the selection of construction profession. © 2015 Published by Elsevier Ltd.

Belash T.,Saint Petersburg State University
Procedia Engineering | Year: 2015

One of the serious problems in field of building seismic stability provision is the restriction of dangerous displacements occurring due to low-frequency seismic impact. Restriction of these displacements would be possible by means of application of special damping elements placed at the levels of floors. Dry friction dampers are considered to be such elements. © 2015 Published by Elsevier Ltd.

Pukhkal V.,Saint Petersburg State University
Procedia Engineering | Year: 2015

Residential housing in Saint-Petersburg built-up in 1960-1995 can be featured by poor thermal properties. New requirements assigned for energy efficiency of buildings called for insulation. Heat losses are primarily specified by thermal properties of building envelopes depending on what humidity conditions construction materials are exposed to. High humidity of exterior walls can result in diminution of thermal properties and increase in heat losses. Besides, excessive moistening of envelopes may lead to cladding peeling, their deterioration and service life reduction. When designing building envelopes a crucial issue a forecast of temperature and humidity conditions for buildings in service. The article deals with an option for exterior walls insulation in the case of buildings with protective finishing coating made of thin plaster. A structure for external walls insulation based on heat insulating slabs made of rock wool has been taken. A required thickness of an insulation material has been determined, and an analysis of humidity conditions for insulated and non-insulated exterior walls has been performed. © 2015 Published by Elsevier Ltd.

Gamayunova O.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The Civil Engineering Institute is a leader in training of students in civil engineering programs. Strong leadership of the Polytechnical University among other universities which implement the training of students in civil engineering programs in the eyes of students and their parents evolved gradually. Of course, on this worked and the overall image of the educational institution which has the status of National Research University. There are only four institutions of higher learning in the field of Civil Engineering with such a status in our country. The only one is in St. Petersburg. It is the St. Petersburg State Polytechnical University. This article describes the achievements of students and teachers of the Civil Engineering Institute, analyzed the results of the admission campaign of this year. © 2015 Published by Elsevier Ltd.

Andrey B.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The article examines the process of development and implementation of a new training course for students of St. Petersburg Polytechnic University majoring in Construction - "Social Management Technologies in Construction". A theoretical foundation for the lecture course and the practical aspects of teaching are presented. The discipline is considered as a mandatory component of the humanities in engineering education. © 2015 Published by Elsevier Ltd.

Galkina O.V.,Saint Petersburg State University
Neurochemical Journal | Year: 2013

Here we review the specific features of free-radical processes in the CNS. We review the pathways of the generation of reactive oxygen species in nervous nerve tissue, the specific parameters of substrates of free-radical oxidation, and the contents and activities of various antioxidants. We briefly describe some physiological effects of reactive oxygen species in the nervous tissue. © 2013 Pleiades Publishing, Ltd.

Gamayunova O.,Saint Petersburg State University
Procedia Engineering | Year: 2015

Civil engineering specialties traditionally are in stable demand of graduates of schools for many years. Following the results of the admission campaign in major universities in St. Petersburg, offering training in the construction industry, competition and the passing score were high. This article describes the supply and demand in the labor market in the segment of "Construction", and presents the basic possibility of obtaining construction education in St. Petersburg. © 2015 Published by Elsevier Ltd.

Zayats I.,Saint Petersburg State University
Procedia Engineering | Year: 2015

Interdependence of the architectural form with function is one of permanently open questions in the architectural theory. The paper describes the history of development mills in Russia in the context of architectural traditions. The use of wind and water engine was a real engineering breakthrough and by the end of the XIX century had been determining the nature of many types of industries. Architectural principles of the mills construction determined common European technological advances and development. The choice of the mill type depended only on the conditions of the building. Mills were built around by a project or likeness. Mill buildings were utilitarian and functional. Changing the architectural appearance of mills associated with the process and its improvement. The peculiar features of the mill buildings appeared only in connection with the characteristic of particular region general construction technologies, traditional building materials and the level of construction equipment. © 2015 Published by Elsevier Ltd.

Romanyuk K.,Saint Petersburg State University
Procedia Engineering | Year: 2015

The paper investigates into allocation of treasury funds when major repairs are being funded. Slum clearance is part of major repairs costs. It is shown that mortgage lending can be used to reduce loading on treasury funds and make slum clearance quicker. The world experience in mortgage lending improvement is studied. In particular, mortgage securitization effect is looked into. A model of government co-financing of mortgage lending is proposed. The effect on economic performances due to application of this model is assessed. Guidelines are suggested in order to maintain high quality of the mortgage portfolio. © 2015 Published by Elsevier Ltd.

Golovina S.,Saint Petersburg State University
Procedia Engineering | Year: 2015

An optimal network of state educational institutions has been developed in Saint-Petersburg. It has been streamlined over the last years, and now it can be represented as unique public instructional environment which makes it possible for children of any educational institution to elicit their creative potential. The article deals with a brief analysis related to forecast of general education development in Saint-Petersburg. Modernization of educational institutions and school facilities is considered in the context of the architectural typology and city planning, and energy efficiency. © 2015 Published by Elsevier Ltd.

Lisovenko A.S.,Saint Petersburg State University | Timoshkin A.Y.,Saint Petersburg State University
Inorganic Chemistry | Year: 2010

Donor-acceptor complexes of borazine (BZ) and its substituted derivatives with Lewis acids (A = MCl3, MBr3; M = B, Al, Ga) and Lewis bases (D = NH3, Py) have been theoretically studied at the B3LYP/TZVP level of theory. The calculations showed that complexes with Lewis bases only are unstable with respect to dissociation into their components, while complexes with Lewis acids only (such as aluminum and gallium trihalides) are stable. It was shown that formation of ternary D→BZ→A complexes may be achieved by subsequent introduction of the Lewis acid (acceptor A) and the Lewis base (donor D) to borazine. The nature of substituents in the borazine ring, their number, and position were shown to have only minor influence on the stability of ternary D→BZ→A complexes due to the compensation effect. Much weaker acceptor properties of borazine are explained in terms of large endothermic pyramidalization energy of the boron center in the borazine ring. In contrast to borazine, binary complexes of the isoelectronic benzene were predicted to be weakly bound even in the case of very strong Lewis acids; ternary DA complexes of benzene were predicted to be unbound. The donor-acceptor complex formation was predicted to significantly reduce both the endothermicity (by 70-95 kJ mol-1) and the activation energy (by 40-70 kJ mol -1) for the borazine hydrogenation. Thus, activation of the borazine ring by Lewis acids may be a facile way for the hydrogenation of borazines and polyborazines. © 2010 American Chemical Society.

Averianov A.O.,Saint Petersburg State University | Martin T.,University of Bonn | Lopatin A.V.,Russian Academy of Sciences
Naturwissenschaften | Year: 2013

The endemic South American mammals Meridiolestida, considered previously as dryolestoid cladotherians, are found to be non-cladotherian trechnotherians related to spalacotheriid symmetrodontans based on a parsimony analysis of 137 morphological characters among 44 taxa. Spalacotheriidae is the sister taxon to Meridiolestida, and the latter clade is derived from a primitive spalacolestine that migrated to South America from North America at the beginning of the Late Cretaceous. Meridiolestida survived until the early Paleocene (Peligrotherium) and early Miocene (Necrolestes) in South America, and their extinction is probably linked to the increasing competition with metatherian and eutherian tribosphenic mammals. The clade Meridiolestida plus Spalacotheriidae is the sister taxon to Cladotheria and forms a new clade Alethinotheria. Alethinotheria and its sister taxon Zhangheotheria, new clade (Zhangheotheriidae plus basal taxa), comprise Trechnotheria. Cladotheria is divided into Zatheria (plus stem taxa, including Amphitherium) and Dryolestida, including Dryolestidae and a paraphyletic array of basal dryolestidans (formerly classified as "Paurodontidae"). The South American Vincelestes and Groebertherium are basal dryolestidans. © 2013 Springer-Verlag Berlin Heidelberg.

Stishkov Y.K.,Saint Petersburg State University | Chirkov V.A.,Saint Petersburg State University
Technical Physics | Year: 2012

The main features of the formation of electrohydrodynamic (EHD) flows are analyzed for two basic regimes of electrization of weakly conducting liquids: injection from the electrode surface and dissociation in the bulk. Analysis is carried out on the basis of the results of computer simulation of EHD flows in a strongly nonuniform electric field in the needle-plane electrode system. This system creates favorable conditions for the injection as well as dissociation mechanisms of charge formation. Typical features are revealed for each model of charge formation. The current-time characteristics of the transient process of stabilization of EHD flows are calculated. © 2012 Pleiades Publishing, Ltd.

Samsonov A.A.,Saint Petersburg State University | Sibeck D.G.,NASA | Yu Y.,University of Michigan
Journal of Geophysical Research: Biogeosciences | Year: 2010

We use results from a global MHD simulation to study the interaction of an interplanetary shock with the Earth's magnetosphere for a northward interplanetary magnetic field orientation. We connect intensifications of the transient northward Bz (NBZ) and Region 1 currents in the ionosphere with the appearance of two strong dynamo regions in the magnetosphere: the first on the high-latitude magnetopause near and behind the cusps and the second near the equatorial plane on the flanks. The ionospheric and magnetospheric transients are well synchronized and move antisunward gradually. According to the results obtained, the source of energy for the transient NBZ current is related to shock-intensified lobe reconnection, while the transient Region 1 current corresponds to the reflected fast shock predicted by Samsonov et al. (2007). We speculate that the electric circuits for the quasi-stationary field-aligned currents are similar to the transient electric circuits obtained in this paper. Copyright 2010 by the American Geophysical Union.

Kulikov K.G.,Saint Petersburg State University
Technical Physics | Year: 2012

An electrodynamic model of reflection of a plane wave from a layer simulating a biological structure with a slowly varying thickness is constructed with allowance for roughness in the case when the characteristic size of inhomogeneities on the surface is much larger than the wavelength. The model makes it possible to vary the size of inhomogeneities on the rough surface, the electrophysical parameters of the biological sample under investigation, and the geometrical parameters and to establish the dependences between these parameters and the biological properties of the biotissue being simulated. © 2012 Pleiades Publishing, Ltd.

Bozhokin S.V.,Saint Petersburg State University
Technical Physics | Year: 2012

An analytic expression for a continuous wavelet transform (CWT) is obtained for a nonstationary signal with spectral properties varying with time. As a model of the nonstationary signal, a superposition of elementary nonstationary signals is considered, each of which is the product of the Gaussian-shape envelope and an oscillating function. To obtain the CWT, the mother Morlet wavelet is used. The result is compared with the window Fourier transform (Gabor transform). The advantages of the CWT are illustrated by concrete examples. The applications of the exactly solvable model of nonstationary signals for simulating transient processes in physics are considered. © 2012 Pleiades Publishing, Ltd.

Rebane T.K.,Saint Petersburg State University
Journal of Experimental and Theoretical Physics | Year: 2012

The energy and eigenstate spectrum of a charged particle in the electric field of a 2D anisotropic oscillator and in a uniform magnetic field is considered. The exact analytic solution to the problem is obtained for an arbitrary magnetic field strength. The characteristic features of variation of the energy spectrum depending on the magnetic field strength are analyzed. The results of this study are of interest for the quantum-mechanical theory of magnetism and can be used to simulate the magnetic properties of atoms and molecules. © Pleiades Publishing, Inc., 2012.

Trubilko A.I.,Saint Petersburg State University
JETP Letters | Year: 2012

Collective operators corresponding to two different algebras have been introduced for a simple system consisting of a single two-level atom and a high-quality cavity mode. The generators of the first algebra satisfy boson commutation relations, whereas the generators of the second algebra have been obtained by polynomial deformation of su(2) algebra. It has been shown that dual squeezed states identified using the considered commutation relations can be observed in the system placed in an entangled bath with quantum correlations. © 2012 Pleiades Publishing, Ltd.

Rebane T.K.,Saint Petersburg State University
Physics of Atomic Nuclei | Year: 2012

Drozdovskii A.V.,Saint Petersburg State University | Kalinikos B.A.,Saint Petersburg State University
JETP Letters | Year: 2012

The emergence of the self-modulation instability of monochromatic microwave spin waves excited in a periodic magnetic film structure, a magnonic crystal, has been observed. The magnonic crystal was fabricated by chemically etching the surface a single-crystal yttrium-iron garnet film. The self-modulation instability has been observed at the frequencies corresponding to the band gaps of the spin-wave spectrum of the magnonic crystal caused by Bragg resonances. Above a certain threshold value of the input microwave signal, the time profile of the output pulses corresponds to envelope solitons. © 2012 Pleiades Publishing, Ltd.

Nazarov A.,Saint Petersburg State University
JETP Letters | Year: 2012

Schramm-Loewner evolution (SLE) and conformal field theory (CFT) are popular and widely used instruments to study critical behavior of two-dimensional models, but they use different objects. While SLE has natural connection with lattice models and is suitable for strict proofs, it lacks computational and predictive power of conformal field theory. To provide a way for the concurrent use of SLE and CFT, CFT correlation functions, which are martingales with respect to SLE, are considered. A relation between parameters of Schramm-Loewner evolution on coset space and algebraic data of coset conformal field theory is revealed. The consistency of this approach with the behavior of parafermionic and minimal models is tested. Coset models are connected with off-critical massive field theories and implications of SLE are discussed. © 2012 Pleiades Publishing, Ltd.

Desnitskiy A.G.,Saint Petersburg State University
Russian Journal of Developmental Biology | Year: 2014

This paper presents a brief survey and preliminary classification of embryonic cleavage patterns in the class Amphibia. We use published data on 41 anuran and 22 urodele species concerning the character of the third cleavage furrow (latitudinal or longitudinal) and the stage of transition from synchronous to asynchronous blastomere divisions in the animal hemisphere (4-8-celled stage, 8-16-celled stage or later). Based on this, four patterns of amphibian embryonic cleavage are recognized, and an attempt to elucidate the evolutionary relationships among these patterns is undertaken. The so-called "standard" cleavage pattern (the extensive series of synchronous blastomere divisions including latitudinal furrows of the third cleavage) with the typical model species Ambystoma mexicanum and Xenopus laevis seems to be derived and probably originated independently in the orders Anura and Caudata. The ancestral amphibian cleavage pattern seems to be represented by species with longitudinal furrows of the third cleavage and the loss of synchrony as early as the 8-celled stage (such as in primitive urodele species from the family Cryptobranchidae). © 2014 Pleiades Publishing, Inc.

Andronov I.V.,Saint Petersburg State University
IEEE Antennas and Wireless Propagation Letters | Year: 2013

New high-frequency asymptotic formulas are presented for electromagnetic and acoustic problems of scattering by asymptotically strongly elongated spheroids. Numerical computations show that when spheroids becomes less elongated, scattering cross sections tend to the classical high-frequency limit. © 2002-2011 IEEE.

Ponomarev A.,Saint Petersburg State University
IEEE Transactions on Automatic Control | Year: 2016

Lyapunov-Krasovskii approach is applied to parameter-robustness and delay-robustness analysis of the feedback suggested by Manitius and Olbrot for a linear time-invariant system with distributed input delay. A functional is designed based on Artstein's system reduction technique. It depends on the norms of the reduction-transformed plant state and original actuator state. The functional is used to prove that the feedback is stabilizing when there is a slight mismatch in the system matrices and delay values between the plant and controller. © 2015 IEEE.

Proskurnikov A.,Saint Petersburg State University
Automatica | Year: 2013

Consensus algorithms for multi-agent networks with high-order agent dynamics, time-varying topology, and uncertain symmetric nonlinear couplings are considered. Convergence conditions for these algorithms are obtained by means of the Kalman-Yakubovich-Popov lemma and absolute stability techniques. The conditions are similar in spirit and extend the celebrated circle criterion for the stability of Lurie systems. © 2012 Elsevier Ltd. All rights reserved.

Kharitonov V.L.,Saint Petersburg State University
Annual Reviews in Control | Year: 2010

In this contribution we present some basic results concerning the computation of quadratic functionals with prescribed time derivatives for linear time delay systems. Some lower and upper bounds for the functionals are given. The functionals are defined by special matrix valued functions. These functions are called Lyapunov matrices. The theory of the matrices is a rather young topic. Therefore, principal results with respect to the existence and uniqueness of the matrices are included. Some important applications of the functionals are pointed out. A brief historical survey ends the contribution. © In this contribution we present some basic results concerning the computation of quadratic functionals with prescribed time derivatives for linear time delay systems. Some lower and upper bounds for the functionals are given. The functionals are defined by special matrix valued functions. These functions are called Lyapunov matrices. The theory of the matrices is a rather young topic. Therefore, principal results with respect to the existence and uniqueness of the matrices are included. Some important applications of the functionals are pointed out. A brief historical survey ends the contribution. © 2010 Elsevier Ltd.

Leonov G.A.,Saint Petersburg State University
International Journal of Bifurcation and Chaos | Year: 2013

For Lorenz-like system, conditions of Shilnikov chaos are obtained. Algorithms for computation of bifurcational values of parameters, which correspond to homoclinic trajectories are formulated. Modified Lorenz, Chen and Lu systems are considered. © 2013 World Scientific Publishing Company.

Proskurnikov A.V.,Saint Petersburg State University
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2013

We consider consensus algorithms for multi-agent networks with high-order and delayed dynamics of agents. The topology is assumed to be fixed and undirected, however the couplings may be nonlinear and uncertain, we assume only the symmetry condition to be valid. We obtain conditions of stability for such algorithms that are similar in spirit to the celebrated Popov criterion for the stability of Lurie systems. © IFAC.

Kutcherov D.,Saint Petersburg State University
Journal of Asia-Pacific Entomology | Year: 2016

Insect development times can only be compared over a relatively wide range of permissible temperatures. Both basic and applied branches of entomology widely adopt linear regression that describes the temperature-dependence of developmental rate, which is a reciprocal of time. There is a wealth of literature reporting these parameters for hundreds of economically important species, including leaf beetles. This study begins with a suspicion that the previously published parameters for the temperature-dependent development in the walnut leaf beetle Gastrolina depressa may be imprecise because they disagree with the general variation pattern typical of the family Chrysomelidae. Thus, the immature development in G. depressa is re-studied in order to verify the values of the lower temperature threshold and the slope of developmental rate on temperature. It is found that G. depressa requires 220.2 degree-days accumulated above the threshold of 8.2 °C for total immature development. For example, at 28 °C, the developmental period from oviposition to adult eclosion is as short as 11.4 days. Although development in G. depressa is indeed unusually fast, it does not depart from the general tendencies observed at the family level. Therefore, with extensive published evidence at hand, it has now become possible to approximately predict developmental rates in unstudied species and reveal questionable results in previous studies. In addition, rearing temperature is found to affect adult body mass and sex ratio in this species with males being less abundant at higher temperatures. The latter phenomenon is discussed in light of possible activity of a male-killing microorganism. © 2016 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.

Evarestov R.A.,Saint Petersburg State University | Panin A.I.,Saint Petersburg State University
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2012

Rod groups (monoperiodic subgroups of the 3-periodic space groups) are considered as a special case of the commensurate line groups (discrete symmetry groups of the three-dimensional objects translationally periodic along a line). Two different factorizations of line groups are considered: (1) The standard L = T(a)F used in crystallography for rod groups; F is a finite system of representatives of line-group decomposition in cosets of 1-periodic translation group T(a); (2) L = ZP used in the theory of line groups; Z is a cyclic generalized translation group and P is a finite point group. For symmorphic line groups (five line-group families of 13 families) the two factorizations are equivalent: the cyclic group Z is a monoperiodic translation group and P is the point group defining the crystal class. For each of the remaining eight families of non-symmorphic line groups the explicit correspondence between rod groups and relevant geometric realisations of the corresponding line groups is established. The settings of rod groups and line groups are taken into account. The results are presented in a table of 75 rod groups listed (in international and factorized notation) by families of the line groups according to the order of the principal axis q (q = 1, 2, 3, 4, 6) of the corresponding isogonal point group. © 2012 International Union of Crystallography Printed in Singapore-all rights reserved.

Kudrev A.G.,Saint Petersburg State University
Biophysics (Russian Federation) | Year: 2012

In the present study, the experimental data on the pH-induced formation of the i-motif structure in the nucleotide sequence 5′-CCTTTCCTTTTCCTTTCC-3′ (25°C, pH 3.3-8.9) obtained by spectroscopic techniques, such as UV molecular absorption and circular dichroism, has been analyzed using the chemometric soft modeling-based MCR-ALS approach and the hard modeling-based matrix method. Soft modeling using 2 or 3 spectral species correctly reproduced the spectral variations observed experimentally. The use of hard chemical modeling has allowed proposing an equilibrium model, which describes spectral changes as functions of solution acidity. Additionally, the intrinsic protonation constant Kin and the cooperativity parameter ω have been calculated from fitting of the circular dichroism as well as the molecular absorption spectra. The results indicated that folding was accompanied by a cooperative process, i. e. the enhancement of protonated structure stability upon protonation. © 2012 Pleiades Publishing, Ltd.

Krivovichev S.,Saint Petersburg State University
Acta Crystallographica Section A: Foundations of Crystallography | Year: 2012

The topological complexity of a crystal structure can be quantitatively evaluated using complexity measures of its quotient graph, which is defined as a projection of a periodic network of atoms and bonds onto a finite graph. The Shannon information-based measures of complexity such as topological information content, IG , and information content of the vertex-degree distribution of a quotient graph, I vd, are shown to be efficient for comparison of the topological complexity of polymorphs and chemically related structures. The IG measure is sensitive to the symmetry of the structure, whereas the I vd measure better describes the complexity of the bonding network. © 2012 International Union of Crystallography Printed in Singapore - all rights reserved.

Tetz V.V.,Saint Petersburg State University | Tetz G.V.,Saint Petersburg State University
DNA and Cell Biology | Year: 2010

Biofilm formation plays a crucial role in the development of different infections. This study was designed to examine the effects of extracellular DNA destruction by DNase I on characteristics of forming bacterial biofilms. We have found that extracellular matrix of biofilms formed in the presence of DNase I contains extracellular DNA fragments of about 30kb. These data support the idea that cell-free DNA is constantly released to the extracellular matrix of bacterial biofilms. Our results indicate that extracellular DNA plays an important role in the properties of forming biofilms. Biofilms formed in the presence of DNase I (5.0?μg/mL) displayed reduced biofilm biomass, total bacterial biomass, decreased viability of bacteria, and decreased tolerance to antibiotics. The fact that destruction of extracellular DNA in forming biofilms by DNase I leads to the formation of an altered microbial community with decreased tolerance to environmental factors suggests the possibility to change the characteristics of forming biofilms by modifying cell-free DNA. Copyright 2010, Mary Ann Liebert, Inc.

Demidchik V.,Belarusian State University | Straltsova D.,Belarusian State University | Medvedev S.S.,Saint Petersburg State University | Pozhvanov G.A.,Saint Petersburg State University | And 2 more authors.
Journal of Experimental Botany | Year: 2014

Electrolyte leakage accompanies plant response to stresses, such as salinity, pathogen attack, drought, heavy metals, hyperthermia, and hypothermia; however, the mechanism and physiological role of this phenomenon have only recently been clarified. Accumulating evidence shows that electrolyte leakage is mainly related to K+ efflux from plant cells, which is mediated by plasma membrane cation conductances. Recent studies have demonstrated that these conductances include components with different kinetics of activation and cation selectivity. Most probably they are encoded by GORK, SKOR, and annexin genes. Hypothetically, cyclic nucleotide-gated channels and ionotropic glutamate receptors can also be involved. The stress-induced electrolyte leakage is usually accompanied by accumulation of reactive oxygen species (ROS) and often results in programmed cell death (PCD). Recent data strongly suggest that these reactions are linked to each other. ROS have been shown to activate GORK, SKOR, and annexins. ROS-activated K+ efflux through GORK channels results in dramatic K+ loss from plant cells, which stimulates proteases and endonucleases, and promotes PCD. This mechanism is likely to trigger plant PCD under severe stress. However, in moderate stress conditions, K+ efflux could play an essential role as a 'metabolic switch' in anabolic reactions, stimulating catabolic processes and saving 'metabolic' energy for adaptation and repair needs. © The Author 2014.

Monakov A.,Saint Petersburg State University
Signal Processing | Year: 2013

The problem of signal waveform estimation using an antenna array in case of uncertainties about the steering vector is considered. New asymptotically (in sample size) optimum estimators are derived. In contrast to the known optimal solutions, the employed method of synthesis yields non-iterative direct-form estimators. Simulation results are provided to evaluate the performance of the synthesized estimators. It is shown that the proposed asymptotic estimators perform as well as the iterative optimal estimators and they outperform the MVDR estimator in a wide range of input signal-tonoise and uncertainty ratios. © 2013 Elsevier B.V. All rights reserved.

Gerchikov L.,Saint Petersburg State Polytechnic University | Sheinerman S.,Saint Petersburg State University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Atomic inner-shell photoionization followed by double Auger decay is investigated. The focus of our study is the effect of post-collision interaction (PCI) on the photoelectron energy distribution. A semi-classical approach is employed to describe the PCI distortion of the photoelectron line shapes associated with both direct and cascade double Auger decays. This approach is shown to be valid at low photoelectron energies, whereas for large incident photon energies it reduces to the eikonal approximation. The theory is applied to the case of Ar 2p photoionization spectra and good agreement with available experimental data is achieved. © 2011 American Physical Society.

Telnov D.A.,Saint Petersburg State University | Chu S.-I.,University of Kansas | Chu S.-I.,National Taiwan University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

Recent experimental observations of above-threshold ionization of rare gas atoms and diatomic molecules by midinfrared laser fields revealed a prominent maximum in the electron energy spectrum very close to the ionization threshold which is not reproduced by widely used Keldysh-Faisal-Reiss theories. We have performed fully ab initio theoretical analysis and precision calculations to explore the quantum origin of the low-energy structure (LES) observed in the experiments. Our study shows that an important role in shaping of LES is played by the effect of Coulomb attraction in the final electron state and the Coulomb threshold effect. © 2011 American Physical Society.

Musolin D.L.,Saint Petersburg State University
Physiological Entomology | Year: 2012

The southern green stink bug Nezara viridula (L.) (Heteroptera: Pentatomidae) has long attracted attention not only as a serious pest of numerous agricultural crops, but also as a species expanding its range in many parts of the world. Nezara viridula has also been widely used as a model in different experimental studies. The present review focuses on reproductive (i.e. adult) winter diapause, which is the pivotal element of the species' seasonal cycle. Results from numerous field experiments and observations, as well as laboratory ecophysiological investigations conducted during the few last decades, are analyzed and interpreted. Experimental findings are used to describe in detail the dynamics of physiological changes during overwintering. Reproductive diapause in N. viridula is controlled in both sexes by photoperiodic conditions. The induction of diapause is associated with a reversible change of body colour from green or yellow to russet (or brown). The proper timing of adult emergence and the induction of diapause, as well as the size of adults, is vitally important for successful overwintering. Nezara viridula has been shown to respond strongly to the current trend in climate change by shifting the limit of its northern range, particularly in central Japan. Analysis of historic climate data suggests that the environmental conditions during the last few decades have become more favourable for the overwintering survival of N. viridula in many locations in central Japan. This has likely promoted the northward spread of the species. The relationships between reproductive diapause, reversible body colour change, overwintering success and the recent range expansion are analyzed. Perspectives of the range dynamics of the species are discussed in light of further predicted climate change. © 2012 The Author. © 2012 The Royal Entomological Society.

Malev V.V.,Saint Petersburg State University
Electrochimica Acta | Year: 2015

As known, polaron quasi-particles of conducting polymers contain from 3 to 6 monomer fragments (repeat units) of polymer chains. This is the reason why the widely accepted approach to treating the polaron conductance assumes that the reduced forms of polarons have the same number of repeat units as included into polarons and, moreover, treats such reduced formations as separate quasi-particles. The latter obviously means that charge transfer from a polaron to a neighboring reduced quasi-particle proceeds with simultaneous transformations of all the fragments of these quasi-particles. In other words, the distance of charge transfer in such transitions is assumed to be exactly equal to the polaron size. In contrast to such treatment, the main feature of the proposed approach is a polaron flux reformulation, which assumes a unit polaron translocation to be of a one monomer size independently of number m of monomer fragments included into polaron quasi-particles. As a result, material balance equations of polaron-conducting films take a more complicated form than that accepted in the existing approach. It is shown that, at equilibrium conditions, the obtained equations, as it must be, lead to the relationships being in accordance with thermodynamic ones. At the same time, a proper analysis reveals some differences between quantitative results that follow from the proposed and traditional approaches for both quasi-equilibrium and non-equilibrium conditions. Possible directions of the further development of the represented approach are shortly discussed. © 2015 Elsevier Ltd.

Heslar J.,National Taiwan University | Telnov D.,Saint Petersburg State University | Chu S.-I.,National Taiwan University | Chu S.-I.,University of Kansas
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We present a time-dependent density functional theory (TDDFT) approach with proper asymptotic long-range potential for nonperturbative treatment of high-order harmonic generation (HHG) of diatomic molecules with their molecular axis parallel to the laser field polarization. A time-dependent two-center generalized pseudospectral method in prolate spheroidal coordinate system is used for accurate and efficient treatment of the TDDFT equations in space and time. The theory is applied to a detailed all-electron nonperturbative investigation of HHG processes of homonuclear (N2 and F2) and heteronuclear (CO, BF, and HF) molecules in intense ultrashort laser pulses with the emphasis on the role of multiple molecular orbitals (MOs). The results reveal intriguing and substantially different nonlinear optical response behaviors for homonuclear and heteronuclear molecules. In particular, we found that the HHG spectrum for homonuclear molecules features a destructive interference of MO contributions while heteronuclear molecules show mostly constructive interference of orbital contributions. © 2011 American Physical Society.

Petrov A.N.,Saint Petersburg State University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The role of the interaction with the nearest electronic state 3Σ0-+ on the hyperfine structure and magnetic properties of the a(1)[3Σ1+] state of PbO is assessed. The accounting for this contribution leads to the difference between g factors of the J=1 Ω-doublet levels Δg=37×10-4, which is in good agreement with the experimental data Δg=30(8)×10-4. The contribution of this interaction rapidly grows with J. For J=30, the difference of g factors of Ω-doublet states reaches 100%; for hyperfine constants, it reaches 18%. These differences also depend on the electric field, and, for E=11 V/cm for Pb207O, the difference in g factors turns to zero. The latter is important for suppressing systematic effects in the electron electric dipole moment search experiment. © 2011 American Physical Society.

Berezin A.S.,St Petersburg State Chemical Pharmaceutical Academy | Skorik Y.A.,Saint Petersburg State University
Carbohydrate Polymers | Year: 2015

Novel water-soluble chitosan-isoniazid conjugates were synthesized by two methods: (1) the carbodiimide method using isoniazid (INH) and N-(2-carboxyethyl)chitosan (CEC), and (2) the reaction between INH and N-(3-chloro-2-hydroxypropyl)chitosan (CHPC). The solubility of the conjugates under physiological conditions was enhanced by phosphorylation. Method (1) is preferable in terms of obtaining conjugates with a high content of active substance; depending on reaction conditions, the degree of substitution in the INH-CEC conjugates varies from 0.08 to 0.39. Ultrasound treatment increased the reaction rate by a factor of 1.3-1.5, but caused partial degradation of the polymer. Consecutive modification led to a considerable decrease in polymer biodegradability in the following order: chitosan > CEC or CHPC > conjugate. In vitro screening of the antimicrobial activity against Mycobacterium tuberculosis H37Rv demonstrated a comparable or slightly higher minimum inhibitory concentration for conjugates than for INH itself (0.20, 0.25, and 1.05 μg INH/mL for INH, CEC-INH, and CHPC-INH, respectively). A slug mucosal irritation test employing Limax flavus revealed a lower toxicity for the conjugates than for INH by a factor of 3-4; the most noticeable toxicity decrease was observed for the conjugates obtained by method (1). Studies of acute toxicity in mice revealed a 3-4-fold increase in median lethal dose for the conjugates compared with INH (LD50 210, 850, and 650 mg INH/kg for INH, CEC-INH, and CHPC-INH, respectively). © 2015 Elsevier Ltd. All rights reserved.

Andrianov S.N.,Saint Petersburg State University | Kulabukhova N.,Saint Petersburg State University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

In this paper we discuss some problems of the construction of mathematical models of dynamic processes to effectively carry out computational experiments using high performance computing systems (both parallel and distributed). The suggested approach is based on the Lie algebraic approach and the multi-agents paradigm. The Lie algebraic tools demonstrated high effectiveness in dynamical systems modeling. A matrix presentation for dynamical systems propagation allows to implement a modular representation of the objects of study as well as the corresponding operations. Moreover, the matrix formalism is based upon the multi-agent paradigm for modeling and control of complex systems for physical facilities. The corresponding codes are realized both in symbolic and numerical forms. © Springer International Publishing Switzerland 2016.

Emel'yanov O.A.,Saint Petersburg State University
Technical Physics | Year: 2011

A mechanism of the electrical breakdown is proposed for modern metal-field capacitors with the well-known property of self-healing of the breakdown strength. Upon an increase in the working voltage, the self-healing time increases to tens of microseconds, and the heating of adjacent insulator layers becomes significant. The propagating thermally activated conduction wave facilitates the enhancement of the electric field up to breakdown values. Analysis of the dynamics of electric field increase is carried out for capacitors based on polyethylene terephthalate (PET) dielectric. © 2011 Pleiades Publishing, Ltd.

Krasnova N.K.,Saint Petersburg State University
Technical Physics | Year: 2011

The electronic and optical characteristics of 2D electric fields with a complex potential of the type Ω = i(x + iy)n, where n is a real number, are investigated. Particle dynamics is studied in the symmetry plane and in its neighborhood for constructing an effective spectrograph of electron flows. It is shown that in the range of exponents 0 < n < 1, spatial focusing in the angles of incidence of conical bunches is effected in the system, which has second order in the symmetry plane and at least the first order across it. The line of images of a point source (focal line) is a straight line lying in the symmetry plane, the focusing order being independent of particle energy W. Thus, the spectrographic principle holds, and partial electron fluxes can be detected simultaneously by a position-sensitive detector in a wide range of energy variation. The electrode configuration of these systems is quite simple and can be used in practice for constructing spectrographs. The prospects of application of such spectrographs in energy analysis are considered. © 2011 Pleiades Publishing, Ltd.

Pronina Y.G.,Saint Petersburg State University
Corrosion Science | Year: 2015

The paper presents benchmark solutions for the mechanochemical corrosion of an elastic-perfectly plastic thick-walled spherical shell under internal and external pressure with possible inhibition of corrosion being taken into account. The rates of inner and outer corrosion are linear with equivalent tensile stress at the related surface when the stress increases beyond a certain threshold. The time of initial and complete yielding is determined and compared with the same results for a cylindrical tube that were obtained earlier. © 2014 Elsevier Ltd.

Przhibel'skii S.G.,Saint Petersburg State University
Technical Physics | Year: 2011

Analytical and numerical studies of the energy density spatial distribution of a fluctuating electric field near the model ionic crystal surface as a function of temperature are carried out. It is established that the fluctuating field energy density decreases as h-3.3 with increasing distance h from the crystal surface. The fluctuating field energy increases with temperature and differs from zero at -273°C due to quantum zero-point vibrations of ions in the lattice. © 2011 Pleiades Publishing, Ltd.

Pantserev K.A.,Saint Petersburg State University
ACM International Conference Proceeding Series | Year: 2016

The paper is devoted to the problem of the bridging of the "digital gap" between States of Sub-Saharan Africa and well-developed countries. The author undertakes an attempt of theoretical comprehension of the problem of the digital divide and try to understand which kind of measures are undertaken by Sub-Saharan African countries which dispose strictly limited financial and technological resources and are dependent from foreign aid in order to reduce the digital gap and to build an information society in the region. © 2016 ACM.

Valiev F.F.,Saint Petersburg State University
Bulletin of the Russian Academy of Sciences: Physics | Year: 2011

We propose a new approach to electromagnetic field calculations that involves the consecutive application of both quantum and classical electrodynamics methods. A current's distribution is calculated via simulation modeling, using cross-section values obtained through quantum electrodynamics. The classical delayed potential of a current pulse of arbitrary form and duration, moving in a straight line at hyperlight velocity in the space-time representation, is calculated in an explicit form. © 2011 Allerton Press, Inc.

Golovitskii A.P.,Saint Petersburg State University
Technical Physics | Year: 2011

The model of the positive column (PC) of a moderate-pressure (5-30 Torr) glow discharge in a mixture of inert gases and chlorine under currents of up to 50 mA/cm2 extends the existing models of discharges in electronegative gases. The novelty of the model is the inclusion of radial nonuniformity in the gas temperature and dissociation of chlorine molecules into atoms, as well as allowance for heating of ions by the electric field and step ionization. As a result, the calculated radial profiles of charged particle concentrations are not only in qualitative agreement with earlier-developed theories of electronegative discharges, but also in quantitative agreement with experimental data. It is shown that allowance for dissociation of chlorine molecules and the effect of longitudinal field Ez on the ion temperatures is essential for this conformity in the model of the PC of a glow discharge in the mixture of inert gases and chlorine. However, radial field Er can be disregarded in estimating the ion temperatures. The smallness of the contribution of the ion current to the total current of the discharge, which had earlier only been postulated, is demonstrated. It is shown that diffusion-aided removal is the predominant mechanism of perishing of electrons and positive ions; for this reason, electron-ion recombination (as well as ion-ion recombination in the balance of positive ions) can be disregarded. © 2011 Pleiades Publishing, Ltd.

Koeppe B.,Free University of Berlin | Tolstoy P.M.,Free University of Berlin | Tolstoy P.M.,Saint Petersburg State University | Limbach H.-H.,Free University of Berlin
Journal of the American Chemical Society | Year: 2011

Combined low-temperature NMR/UV-vis spectroscopy (UVNMR), where optical and NMR spectra are measured in the NMR spectrometer under the same conditions, has been set up and applied to the study of H-bonded anions A· middot;H middot; middot;X- (AH = 1-13C-2-chloro-4-nitrophenol, X- = 15 carboxylic acid anions, 5 phenolates, Cl-, Br -, I-, and BF4 -). In this series, H is shifted from A to X, modeling the proton-transfer pathway. The 1H and 13C chemical shifts and the H/D isotope effects on the latter provide information about averaged H-bond geometries. At the same time, red shifts of the π-π* UV-vis absorption bands are observed which correlate with the averaged H-bond geometries. However, on the UV-vis time scale, different tautomeric states and solvent configurations are in slow exchange. The combined data sets indicate that the proton transfer starts with a H-bond compression and a displacement of the proton toward the H-bond center, involving single-well configurations A-H⋯X-. In the strong H-bond regime, coexisting tautomers A · ·H⋯X- and A-⋯H ··X are observed by UV. Their geometries and statistical weights change continuously when the basicity of X- is increased. Finally, again a series of single-well structures of the type A-⋯H-X is observed. Interestingly, the UV-vis absorption bands are broadened inhomogeneously because of a distribution of H-bond geometries arising from different solvent configurations. © 2011 American Chemical Society.

Baluev R.V.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

We consider the 'multifrequency' periodogram, in which the putative signal is modelled as a sum of two or more sinusoidal harmonics with independent frequencies. It is useful in cases when the data may contain several periodic components, especially when their interaction with each other and with the data sampling patterns might produce misleading results. Although themultifrequency statistic itself was constructed earlier, for example by G. Foster in his CLEANest algorithm, its probabilistic properties (the detection significance levels) are still poorly known and much of what is deemed known is not rigorous. These detection levels are nonetheless important for data analysis.We argue that to prove the simultaneous existence of all n components revealed in a multiperiodic variation, it is mandatory to apply at least 2n - 1 significance tests, among which most involve various multifrequency statistics, and only n tests are single-frequency ones. The main result of this paper is an analytic estimation of the statistical significance of the frequency tuples that the multifrequency periodogram can reveal. Using the theory of extreme values of random fields (the generalized Rice method), we find a useful approximation to the relevant false alarm probability. For the double-frequency periodogram, this approximation is given by the elementary formula (π/16)W2e-zz2, where W denotes the normalized width of the settled frequency range, and z is the observed periodogram maximum. We carried out intensive Monte Carlo simulations to show that the practical quality of this approximation is satisfactory. A similar analytic expression for the general multifrequency periodogram is also given, although with less numerical verification. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Bobylev V.V.,Saint Petersburg State University | Bajkova A.T.,Russian Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2013

To estimate the parameters of the Galactic spiral structure - namely the pitch angle i and the number of spiral arms - data on Galactic masers with known trigonometric parallaxes were used. We applied the well-known method based on analysis of the 'position angle - distance logarithm' diagram. Estimates of the pitch angle i obtained from four segments of different arms belonging to the global Galactic structure are self-consistent and close to i=-13° ± 1°. The segment which is most interesting is that of the Outer arm. It contains only three masers. Hence, in order to obtain correct estimates, we also used the data on 12 very young star clusters with distances determined by Camargo et al. from infrared photometry. The estimates obtained allow us to conclude in favour of the four-armed model of the Galactic spiral structure. © 2013 The Authors.

Igoshev A.P.,Saint Petersburg State University | Popov S.B.,Moscow State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

We analyse different possibilities to explain the wide initial spin period distribution of radio pulsars presented by Noutsos et al. With a population synthesis modelling, we demonstrate that magnetic field decay can be used to interpret the difference between the recent results by Noutsos et al and those by Popov and Turolla, where a much younger population of neutron stars associated with supernova remnants with known ages has been studied. In particular, an exponential field decay with Τ mag = 5 Myr can produce a 'tail' in the reconstructed initial spin period distribution up to P0 > 1 s starting with a standard Gaussian with P0 = 0.3 s and σ = 0.15 s. Another option to explain the difference between initial spin period distributions from Noutsos et al. and Popov and Turolla - the emerging magnetic field - is also briefly discussed. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Baluev R.V.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

We perform a detailed analysis of the latest HARPS and Keck radial velocity data for the planet-hosting red dwarf GJ 581, which attracted a lot of attention in recent time. We show that these data contain important correlated noise component ('red noise') with the correlation time-scale of the order of 10 d. This red noise imposes a lot of misleading effects while we work in the traditional white-noise model. To eliminate these misleading effects, we propose a maximum-likelihood algorithm equipped by an extended model of the noise structure. We treat the red noise as a Gaussian random process with an exponentially decaying correlation function. Using this method we prove that (i) planets b and c do exist in this system, since they can be independently detected in the HARPS and Keck data, and regardless of the assumed noise models; (ii) planet e can also be confirmed independently by both the data sets, although to reveal it in the Keck data it is mandatory to take the red noise into account; (iii) the recently announced putative planets f and g are likely just illusions of the red noise; (iv) the reality of the planet candidate GJ 581 d is questionable, because it cannot be detected from the Keck data, and its statistical significance in the HARPS data (as well as in the combined data set) drops to a marginal level of 2γ, when the red noise is taken into account. Therefore, the current data for GJ 581 really support the existence of no more than four (or maybe even only three) orbiting exoplanets. The planet candidate GJ 581 d requests serious observational verification. © 2012 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society.

Savchenko S.S.,Saint Petersburg State University | Reshetnikov V.P.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

We present a detailed photometric study and measurements of spiral arm pitch angles for a sample of 50 non-barred or weakly barred grand-design spiral galaxies selected from Sloan Digital Sky Survey. In order to find pitch angles, we used a new method based on the window Fourier analysis of their images. This method allows us not only to infer the average pitch angle, but to obtain its value as a function of galactocentric radius as well. Our main results are as follows: (1) Spiral arms of most galaxies cannot be described by a single value of the pitch angle. About 2/3 of galaxies demonstrate pitch angle variations exceeding 20 per cent. In most galaxies in the sample their pitch angle decreases by increasing the distance from the centre. (2) Pitch angle variations correlate with the properties of galaxies - with the shape of the surface brightness distribution (envelope-type or truncated disc), and with the sign of stellar disc colour gradient. (3) More luminous and bright bulges produce more tightly wound spiral arms, that is in agreement with current models for spiral arms formation. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Pitjeva E.V.,Russian Academy of Sciences | Pitjev N.P.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

The high precision of the latest version of the planetary ephemeris Ephemerides of the Planets and the Moon (EPM2011) enables one to explore more accurately a variety of small effects in the Solar system. The processing of about 678 thousand of position observations of planets and spacecraft for 1913-2011 with the predominance of modern radar measurements resulted in improving the PPNparameters, dynamic oblateness of the Sun, secular variation of the heliocentric gravitational constant GM⊙, and the stronger limits on variation of the gravitational constant G. This processing made it possible to estimate the potential additional gravitational influence of dark matter on the motion of the Solar system bodies. The density of dark matter dm, if any, turned out to be substantially below the accuracy achieved by the present determination of such parameters. At the distance of the orbit of Saturn the density ρdm is estimated to be under 1.1 × 10-20 g cm-3, andthe mass of dark matter in the area inside the orbit of Saturn is less than 7.9 × 10-11 M⊙ even takinginto account its possible tendency to concentrate in the centre. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Baluev R.V.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

This paper introduces an extension of the linear least-squares (or Lomb-Scargle) periodogram for the case when the model of the signal to be detected is non-sinusoidal and depends on unknown parameters in a non-linear manner. The problem of estimating the statistical significance of candidate periodicities found using such non-linear periodograms is examined. This problem is related to the task of quantifying the distributions of the maximum values of these periodograms. Based on recent results in the mathematical theory of extreme values of a random field (the generalized Rice method), a general approach is provided to find a useful analytic approximation for these distributions. This approximation has the general form e-z} P(√z), where P is an algebraic polynomial and z is the periodogram maximum.The general tools developed in this paper can be used in a wide variety of astronomical applications, for instance in the study of variable stars and extra-solar planets. With this in mind, we develop and consider in detail the so-called von Mises periodogram - a specialized non-linear periodogram in which the signal is modelled by the von Mises periodic function exp (ν cos ωt). This simple function with an additional non-linear parameter ν can model the light curves of many astronomical objects that show various types of periodic photometric variability. We prove that our approach can be perfectly applied to this non-linear periodogram.We provide a package of auxiliary C++ programs, attached as online-only material. These programs should facilitate the use of the von Mises periodogram in practice. © 2013 The Author. Published by Oxford University Press on behalf of the Royal Astronomical Society.

International Journal of Modern Physics A | Year: 2016

The renormalizability of the Yang-Mills quantum field theory in four-dimensional space-time is discussed in the background field formalism. © 2016 World Scientific Publishing Company.

Bykov A.M.,Saint Petersburg State University | Gladilin P.E.,Saint Petersburg State University | Osipov S.M.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2013

Powerful stellar winds and supernova explosions with intense energy release in the form of strong shock waves can convert a sizeable part of the kinetic energy release into energetic particles. The star-forming regions are argued as a favourable site of energetic particle acceleration and could be efficient sources of non-thermal emission. We present here a non-linear time-dependent model of particle acceleration in the vicinity of two closely approaching fast magnetohydrodynamic (MHD) shocks. Such MHD flows are expected to occur in rich young stellar cluster where a supernova is exploding in the vicinity of a strong stellar wind of a nearby massive star. We find that the spectrum of the high-energy particles accelerated at the stage of two closely approaching shocks can be harder than that formed at a forward shock of an isolated supernova remnant. The presented method can be applied to model particle acceleration in a variety of systems with colliding MHD flows. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Giljov A.,Saint Petersburg State University | Karenina K.,Saint Petersburg State University | Malashichev Y.,Saint Petersburg State University
Animal Behaviour | Year: 2012

In many primate species, bipedal stance is a factor increasing manual laterality. To understand this phenomenon better, there is a need to investigate forelimb preferences in nonprimate mammals with bipedal locomotion as the preferred gait, such as bipedal hopping marsupials. We studied laterality in forelimb use in 27 adult red-necked wallabies during their usual daily activity in five zoos. During feeding from the bipedal position adult wallabies displayed group-level left-forelimb preference with the majority of individuals being lateralized. However, no lateralization was found at the group level during feeding from the quadrupedal position, with only a few animals expressing individual preferences. Wallabies showed significant group-level bias while using the right forelimb for supporting the body in the tripedal stance, with nearly half the individuals being lateralized. On a smaller sample of nine wallabies forelimb preferences in unimanual snout autogrooming were studied: seven individuals preferred to use their left forelimb and two displayed no preference. Additionally, we studied asymmetrical limb use during milk suckling in six young-at-foot wallabies. Here, all subjects more often pulled down the mother's pouch edge with the left forelimb and simultaneously supported the body with the right paw. Our results show that marsupials can display motor laterality at both individual and group levels, comparable with those observed in placentals. Moreover, in red-necked wallabies, much as in primates, the bipedal posture favours the expression of manual laterality, while its direction depends on the functional nature of the motor action. Evolutionary scenarios such as the postural origin theory of behavioural lateralization are discussed. © 2011 The Association for the Study of Animal Behaviour.

Koroleva S.V.,Saint Petersburg State University | Victorov A.I.,Saint Petersburg State University
Physical Chemistry Chemical Physics | Year: 2014

Viscoelastic solutions of ionic surfactants with an added salt exhibit a surprisingly strong dependence of their behavior on the nature of the added coion. We apply a recently proposed molecular-thermodynamic model to elucidate the effect of a coion's specificity on the aggregation of cationic and anionic surfactants. We show that micellar growth and branching are opposed by penetration of coions inside a micelle's corona leading to an increase of the aggregate's preferential curvature. These effects result from hydration/dehydration and dispersion attraction of coions and are only important at high salinity where electrostatic repulsion of coions from the micelle is screened and where branching of micelles and viscosity maxima are observed. At low and medium salinity, the coion plays a minor role; its effect on critical micelle concentration and sphere-to-rod transitions is insignificant. Our molecular-thermodynamic approach describes the specific effects of both counterions and coions and their different roles at different salinity levels based on a unified physical picture. This journal is © the Partner Organisations 2014.

Shelyapina M.G.,Saint Petersburg State University | Fruchart D.,CNRS Neel Institute | Wolfers P.,CNRS Neel Institute
International Journal of Hydrogen Energy | Year: 2010

MgH2 is one of the most promising materials for hydrogen storage. However, its rather slow hydrogen absorption and desorption kinetics and high dissociation temperature essentially limit its application in this field. Nevertheless mixing Mg or MgH2 with small amount of transition metals or their oxides remarkably accelerates the hydrogen kinetics. Recently a series of new hydrides Mg7TiHx, Mg6.5NbHx and Mg6VHx of Ca7Ge type structure has been synthesized. The hydrogen desorption properties have been found to be better than for pure MgH2. Here, we report on the results of our theoretical study of the electronic structure of these new hydrides carried out within the framework of the full-potential, self-consistent linearized augmented plane-wave method. We use these results, along with calculations of the heat of formation and relative stability, to discuss the bonding of these materials and their hydrogen-storage properties. © 2010 Professor T. Nejat Veziroglu.

Amelin K.,Saint Petersburg State University | Granichin O.,Saint Petersburg State University
Proceedings of the American Control Conference | Year: 2012

This paper considers the possibilities of randomized controls for designing confidence regions for unknown parameters. The assumptions about external noise that affect a linear plant are reduced to a minimum: external noise can virtually be arbitrary, but, independently of it, the user must be able to add test perturbations through the input channel. Based on a finite set of observations, we suggest a new procedure which can be used in adaptive control schemes. It has been developed in the general framework of counting of leave-out sign-dominant correlation regions (LSCR), which is mostly being promoted by M. Campi et al. for identification problems. The procedure returns confidence regions which are guaranteed to contain true parameters with a user-chosen probability. The theoretical results are illustrated by an example of a nonminimum-phase second-order plant. © 2012 AACC American Automatic Control Council).

Kazarian M.,Steklov Mathematical Institute | Zograf P.,Saint Petersburg State University
Letters in Mathematical Physics | Year: 2015

We compute the number of coverings of ℂP1\{0, 1,∞} with a given monodromy type over ∞ and given numbers of preimages of 0 and 1. We show that the generating function for these numbers enjoys several remarkable integrability properties: it obeys the Virasoro constraints, an evolution equation, the KP (Kadomtsev–Petviashvili) hierarchy and satisfies a topological recursion in the sense of Eynard–Orantin. © Springer Science+Business Media Dordrecht 2015.

Tsiganov A.V.,Saint Petersburg State University
Journal of Geometry and Physics | Year: 2015

We discuss how to get variables of separation, separated relations and the Lax matrix for the Chaplygin system on the sphere with velocity dependent potential starting with the Lax matrix for other integrable system separable in elliptic coordinates on the sphere. © 2015 Elsevier B.V.

Reshchikov A.V.,Saint Petersburg State University
Zootaxa | Year: 2011

Lathrolestes is recorded from Nepal for the first time. Three new species are described and illustrated: L. roerichi sp. nov., L. lidae sp. nov., L. peisseli sp. nov. This is the first record of the tribe Perilissini from Nepal. Copyright © 2011 Magnolia Press.

Hasselmann K.,Max Planck Institute for Meteorology | Kovalevsky D.V.,Saint Petersburg State University
Environmental Modelling and Software | Year: 2013

As a first step towards extending the MADIAM model reported previously to a model hierarchy MADIAMS (Multi-Actor Dynamic Integrated Assessment Model System), we upgrade the basic economic model M2 of the three model levels M1-M3 of MADIAMS to include non-equilibrium processes. The evolution of the economy is governed by the interactions of a few key aggregated actors (a firm, household, a government and a bank). The economy is treated as a nonlinear system described by a set of system-dynamic equations closed by the specification of the actors' control strategies. The model provides a unified framework for studying the dependence of economic growth and transformation on negotiated wage levels, the rate of investment in human capital (technological innovation), consumption versus savings preferences, government policies and various " animal spirit" processes. The latter are " not the outcome of a weighted average of quantitative benefits" (Keynes) and include unstable feedback responses of firms, consumers and investors to changing supply, demand and price signals, leading to business cycles and speculative boom-and-bust events. The inclusion of these dynamic feedback processes in coupled climate-socio-economic models is important for a realistic assessment of the multi-time-scale impact of climate policies. © 2012 Elsevier Ltd.

Korotyaev E.L.,Saint Petersburg State University
Russian Journal of Mathematical Physics | Year: 2011

The Jacobi operator (Jf)n = an-1fn-1 + anfn+1 + bnfn on ℤ with real finitely supported sequences (an - 1)n∈ℤ and (bn)n∈ℤ is considered. The inverse problem for two mappings (including their characterization): (an, bn, n ∈ ℤ) → {the zeros of the reflection coefficient} and (an, bn, n ∈ ℤ) → {the eigenvalues and the resonances} is solved. All Jacobi operators with the same eigenvalues and resonances are also described. © 2011 Pleiades Publishing, Ltd.

Paston S.A.,Saint Petersburg State University
Theoretical and Mathematical Physics | Year: 2011

We propose a formulation of gravity theory in the form of a field theory in a flat space-time with a number of dimensions greater than four. Configurations of the field under consideration describe the splitting of this space-time into a system of mutually noninteracting four-dimensional surfaces. Each of these surfaces can be considered our four-dimensional space-time. If the theory equations of motion are satisfied, then each surface satisfies the Regge-Teitelboim equations, whose solutions, in particular, are solutions of the Einstein equations. Matter fields then satisfy the standard equations, and their excitations propagate only along the surfaces. The formulation of the gravity theory under consideration could be useful in attempts to quantize it. © 2011 Pleiades Publishing, Ltd.

Livshits A.I.,Saint Petersburg State University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2016

The standard equation of diffusion in heterogeneous media is found to be incomplete. The effect of heterogeneity on diffusion phenomena is commonly considered to be caused by only spatial variations of diffusion coefficient while the spatial difference in the potential energy of diffusing particles due to their interactions with the inhomogeneous medium is not taken into consideration. The possibility of new transport phenomena in heterogeneous media follows from the corrected equation. In particular the great increase of hydrogen permeability through the membranes of metallic alloy is turned out possible due to an optimization of spatial distribution of the alloy composition. © 2016 Elsevier B.V. All rights reserved.

Smirnov V.V.,Saint Petersburg State University
Journal of Physics A: Mathematical and Theoretical | Year: 2010

Some problems of the application of the saddle point method for the estimation of a path integral are considered. The calculation scheme using the approximation of an integrand with entire functions is represented. © 2010 IOP Publishing Ltd.

Butikov E.I.,Saint Petersburg State University
Journal of Physics A: Mathematical and Theoretical | Year: 2011

An enhanced and more exact criterion for dynamic stabilization of the parametrically driven inverted pendulum is obtained: the boundaries of stability are determined with greater precision and are valid in a wider region of the system parameters than previous results. The lower boundary of stability is associated with the phenomenon of subharmonic resonances in this system. The relationship of the upper limit of dynamic stabilization of the inverted pendulum with ordinary parametric resonance (i.e. with destabilization of the lower equilibrium position) is established. Computer simulation of the physical system aids the analytical investigation and proves the theoretical results. © 2011 IOP Publishing Ltd.

Demenkov E.,Saint Petersburg State University | Kulikov A.S.,Steklov Institute of Mathematics
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

A Boolean function f: double-struck F2n → double-struck F 2 is called an affine disperser of dimension d, if f is not constant on any affine subspace of double-struck F2 n of dimension at least d. Recently Ben-Sasson and Kopparty gave an explicit construction of an affine disperser for sublinear d. The main motivation for studying such functions comes from extracting randomness from structured sources of imperfect randomness. In this paper, we show another application: we give a very simple proof of a 3n-o(n) lower bound on the circuit complexity (over the full binary basis) of affine dispersers for sublinear dimension. The same lower bound 3n-o(n) (but for a completely different function) was given by Blum in 1984 and is still the best known. The main technique is to substitute variables by linear functions. This way the function is restricted to an affine subspace of F2n. An affine disperser for sublinear dimension then guarantees that one can make n-o(n) such substitutions before the function degenerates. It remains to show that each such substitution eliminates at least 3 gates from a circuit. © 2011 Springer-Verlag GmbH.

Zolotova N.V.,Saint Petersburg State University | Ponyavin D.I.,Saint Petersburg State University
Astrophysical Journal | Year: 2015

The Maunder Minimum (MM), which occurred between 1645 and 1715, is mainly known as an almost spotless period on the Sun. We analyze the nominal number of sunspot groups for each observer individually. Comparing the sunspot drawings and textual reports, we conclude that the latter underestimate the number of sunspots. We also argue that the different points of view of observers in the seventeenth century on the origin of sunspots resulted in the underestimation of sunspot groups or even gaps in observational reports. We demonstrate that Jean Picard and Giovanni Domenico Cassini of the Paris Observatory did not report any sunspots, while other observers reported on the occurrence of spots. Moreover, compared with other observers, La Hire underestimated the solar activity. The MM looks like an ordinary secular minimum with a depressed 11 yr solar cyclicity. © 2015. The American Astronomical Society. All rights reserved..

Vokhmyanin M.V.,Saint Petersburg State University | Ponyavin D.I.,Saint Petersburg State University
Geophysical Research Letters | Year: 2013

The interplanetary magnetic field (IMF) is the magnetic field of the Sun stretched out by the solar wind. The polarity of the IMF is either positive or negative according to the polarity of the original solar magnetic field. The equivalent ionospheric Disturbance Polar current powered by the azimuthal Y component current system is located at polar latitudes and provides specific geomagnetic variations. It is known that the configuration of this system depends on the polarity of the IMF. Thus, in the absence of direct data in the presatellite era, the IMF sector structure could only be inferred from ground-based geomagnetic observations (Svalgaard,1968; Mansurov,1969). In this paper the IMF polarities have been reconstructed for the nineteenth century for the first time. It is possible due to the advent of the digitized geomagnetic records in the Helsinki and St. Petersburg observatories. These data have been available since 1844 and 1878, respectively. We assume that the reconstructions are reliable enough to study the solar magnetic field of the past. The polarities inferred for the nineteenth and twentieth centuries display similar sector structures. Seasonal variations of the ratio of positive and negative sectors give clear evidence of solar magnetic field reversals starting from the second half of the nineteenth century. © 2013. American Geophysical Union. All Rights Reserved.

Gavrilov N.M.,Saint Petersburg State University | Kshevetskii S.P.,Immanuel Kant Baltic Federal University
Advances in Space Research | Year: 2013

Acoustic-gravity waves (AGWs) observed in the upper atmosphere may be generated near the Earth's surface due to a variety of meteorological sources. Two-dimensional simulations of vertical propagation and breaking of nonlinear AGWs in the atmosphere are performed. Forcing near the Earth's surface is used as the AGW source in the model. We use a numerical method based on finite-difference analogues of fundamental conservation laws for solving atmospheric hydrodynamic equations. This approach selects physically correct generalized solutions of the wave hydrodynamic equations. Numerical simulations are performed in a representative region of the Earth's atmosphere up to altitude 500 km. Vertical profiles of temperature, density, molecular viscosity and heat conductivity were taken from the standard atmosphere model MSIS-90 for January. Calculations were made for different amplitudes and frequencies of lower boundary wave forcing. It is shown that after activating the tropospheric wave forcing, the initial pulse of AGWs may very quickly propagate to altitudes of 100 km and above and relatively slowly dissipate due to molecular viscosity and heat conduction. This may increase the role of transient nonstationary waves in effective energy transport and variations of atmospheric parameters and gas admixtures in a broad altitude range. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.

Malkin Z.,Saint Petersburg State University
Journal of Geodynamics | Year: 2013

Variations in free core nutation (FCN) are associated with different processes in the Earth's fluid core and core-mantle coupling. The same processes are generally caused the variations in the geomagnetic field (GMF) particularly the geomagnetic jerks (GMJs), which are rapid changes in GMF secular variations. Therefore, the joint investigation of variations in FCN and GMF can elucidate the Earth's interior and dynamics. In this paper, we investigated the FCN amplitude and phase variations derived from VLBI observations. Comparison of the epochs of the changes in the FCN amplitude and phase with the epochs of the GMJs indicated that the observed extremes in the FCN amplitude and phase variations were closely related to the GMJ epochs. In particular, the FCN amplitude begins to grow one to three years after the GMJs. Thus, processes that cause GMJs are assumed as sources of FCN excitation. © 2013 Elsevier Ltd.

Popov I.Yu.,Saint Petersburg State University
Physica Scripta | Year: 2011

The problem of flow through a nanotube is considered. Classical fluid mechanics does not give an adequate description of the process. Modified hydrodynamic equations are derived from a microscopic model using the dynamical Bogolyubov approach and the Zwanzig projection operator method. © 2011 The Royal Swedish Academy of Sciences.

Tsiganov A.V.,Saint Petersburg State University
Journal of Physics A: Mathematical and Theoretical | Year: 2011

We discuss the concept of natural Poisson bivectors, which allows us to consider the overwhelming majority of known integrable systems on the sphere in the framework of bi-Hamiltonian geometry. © 2011 IOP Publishing Ltd.

Mosenkov A.V.,Saint Petersburg State University | Sotnikova N.Ya.,Saint Petersburg State University | Reshetnikov V.P.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2010

A sample of edge-on spiral galaxies aimed at a thorough study of the main structural and photometric parameters of edge-on galaxies, both of early- and late-types, is presented. The data were taken from the Two Micron All Sky Survey (2MASS) in the J, H and K s filters. The sources were selected according to their angular size mainly on the basis of the 2MASS-selected Flat Galaxy Catalog (2MFGC). The sample consists of 175 galaxies in the K s filter, 169 galaxies in the H filter and 165 galaxies in the J filter. We present bulge and disc decompositions of each galaxy image. All galaxies have been modelled with a Sérsic bulge and exponential disc with the budda v2.1 package. Bulge and disc sizes, profile shapes, surface brightnesses are provided. Our sample is the biggest up-to-date sample of edge-on galaxies with derived structural parameters for discs and bulges. In this paper, we present the general results of the study of this sample. We determine several scaling relations for bulges and discs which indicate a tight link between their formation and evolution. We show that galaxies with bulges fitted by the Sérsic index n ≲ 2 have quite different distributions of their structural parameters than galaxies with n ≳ 2 bulges. At a first approximation the Sérsic index threshold n ≃ 2 can be used to identify pseudobulges and classical bulges. Thus, the difference in parameter distributions and scaling relations for these subsamples suggests that two or more processes are responsible for disc galaxy formation. The main conclusions of our general statistical analysis of the sample are as follows. The distribution of the apparent bulge axis ratio q b for the subsample with n ≲ 2 can be attributed to triaxial, nearly prolate bulges that are seen from different projections, while n ≳ 2 bulges seem to be oblate spheroids with moderate flattening. Triaxiality of late-type bulges may be due to the presence of a bar that thickened in the vertical direction during its secular evolution. For the sample galaxies, the effective radius of the bulge r e,b, the disc scalelength h and the disc scaleheight z 0 are well correlated. However, there is a clear trend for the ratio r e,b/h to increase with n. As n is an indicator of the Hubble type, such a trend unambiguously rules out the widely discussed hypothesis of a scale-free Hubble sequence. The found correlation between z 0 and r e,b is new and was not described earlier. There is a hint that the fundamental planes of discs, which links only disc parameters and the maximum rotational velocity of gas, are different for galaxies with different bulges. This may indicate a real difference of discs in galaxies with low- and high-concentration bulges. The most surprising result arises from the investigation of the photometric plane of sample bulges. It turns that the plane is not flat and has a prominent curvature towards small values of n. For bulges, this fact was not noted earlier. The clear relation between the flattening of stellar discs h/z 0 and the relative mass of a spherical component, including a dark halo, is confirmed not for bulgeless galaxies but for galaxies with massive bulges. Many of our results are in good agreement with the results of other authors, several ones are new. Thus, our sample is very useful for further detailed studying and modelling of the edge-on spiral galaxies. © 2009 RAS.

Syromyatnikov A.G.,Saint Petersburg State University
International Journal of Geometric Methods in Modern Physics | Year: 2016

It was considered within the framework of the conformal gauge gravitational theory CGTG coupling of the standard model fermions to the axial torsion and preliminary discusses the impact of extra dimensions, in particular, in a five-dimensional space-time with Randall-Sundrum metric, where the fifth dimension is compactified on an S1/Z 2 orbifold, which as it turns out is conformally to the fifth dimension flat Euclidean space with permanent trace of torsion, with a compactification radius R in terms of the radius of a CGTG gravitational screening, through torsion in a process Z μ+μ- and LHC data. In general, have come to the correct set of the conformal calibration curvature the Faddeev-Popov diagram technique type, that follows directly from dynamics. This leads to the effect of restrictions on neutral spin currents of gauge fields by helicity and the Regge's form theory. The diagrams reveals the fact of opening of the fine spacetime structure in a process pp γ/Z/T μ+μ- with a center-of-mass energy of 14TeV, indicated by dotted lines and texture columns, as a result of p-p collision on 1.3 → 10-18cm scales from geometric shell gauge bosons of the SM continued by the heavy axial torsion resonance, and even by emerging from the inside into the outside of the ultra-light (freely-frozen in muon's spin) axial torsion. We then evaluate the contribution of the torsion to the muon anomaly to derive new constraints on the torsion parameters. It was obtained that on the N scattering through the exchange of axial torsion accounting, the nucleon anomalous magnetic moment in the eikonal phase leads to additive additives which is responsible for the spin-flip in the scattering process, the scattering amplitude is classical and characterized by a strong the torsion coupling 1. So the scattering of particles, occurs as on the Coulomb center with the charge fT This is the base model which is the g-2 muon anomaly. The muon anomaly contribution due to the heavy axial vector torsion arises from coupling the muon with torsion as external field. This leads to negative energy additive to mass of muons which makes the missing part of the g-2 muon anomaly. It takes place at reasonable values of the transverse front size of the exact solution CGTG equations types of torsion waves with the spin-flip close to the size of the Compton length muon. © 2016 World Scientific Publishing Company.

Das H.K.,Inter-University Center for Astronomy and Astrophysics | Voshchinnikov N.V.,Saint Petersburg State University | I'lin V.B.,Saint Petersburg State University
Monthly Notices of the Royal Astronomical Society | Year: 2010

We extend and investigate the spheroidal model of interstellar dust grains used to simultaneously interpret the observed interstellar extinction and polarization curves. We compare our model with similar models recently suggested by other authors, study its properties and apply it to fit the normalized extinction A(λ)/A V and the polarizing efficiency P (λ)/A(λ) measured in the near-infrared to far-ultraviolet region for several stars seen through one large cloud. We conclude that the model parameter Ω being the angle between the line of sight and the magnetic field direction can be more or less reliably determined from comparison of the theory and observations. This opens a way to study the spatial structure of interstellar magnetic fields by using multiwavelength photometric and polarimetric observations. © 2010 The Authors. Journal compilation. © 2010 RAS.

Polyakov E.A.,Saint Petersburg State University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

The time-dependent fermionic Hartree-Fock equations can be stochastically extended in such a way as to become the exact representation of quantum dynamics. This fact was first observed in the work of Juillet and Chomaz [Phys. Rev. Lett. 88, 142503 (2002)PRLTAO0031-900710.1103/PhysRevLett.88.142503]. During the past decade, this observation has led to the emergence of a whole family of stochastic wave-function methods for fermions. The common feature of all these methods is that they are based on the expansion of the density operator over the dyadic product of the two fermionic Slater determinant states. In this work, we develop a unified and rigorous foundation for this family of methods. We find a general form of stochastic equations and describe the sufficient conditions under which these methods converge towards exact quantum dynamics. To achieve these goals, we employ the representation of quantum dynamics in generalized phase space. In particular, we consider the quasiprobability distributions which emerge in these stochastic methods and their master equations. It is shown that the convergence towards exact quantum dynamics is controlled by the problem of boundary terms. We provide an example of stochastic Hartree-Fock method which is well-defined and free from this problem. © 2016 American Physical Society.

Kocharov D.,Saint Petersburg State University
Proceedings of the International Multiconference on Computer Science and Information Technology, IMCSIT 2010 | Year: 2010

An experimental research with a goal to automatically detect prominent words in Russian speech is presented in this paper. The proposed automatic prominent word detection system could be further used as a module of an automatic speech recognition system or as a tool to highlight prominent words within a speech corpus for unit selection text-to-speech synthesis. The detection procedure is based on the use of prosodic features such as speech signal intensity, fundamental frequency and speech segment duration. A large corpus of Russian speech of over 200 000 running words was used to evaluate the proposed prosodic features and statistical method of speech data processing. The proposed system is speaker-independent and achieves an efficiency of 84.2 %. © 2010 IEEE.

Eremin D.B.,RAS N. D. Zelinsky Institute of Organic Chemistry | Ananikov V.P.,Saint Petersburg State University
Organometallics | Year: 2014

Acetonitrile solutions of nickel(II) acetylacetonate, which is ubiquitously used in different fields of organometallic chemistry and catalysis, were investigated by means of electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). The detected Ni2(acac)3 + ion with the binuclear Ni2O2 core underwent a wide range of reactions after collision-induced dissociation, leading to a variety of products. Activation of C-H, C-C, and C-O bonds was observed involving the binuclear nickel complex. In sharp contrast, similar ions involving mononuclear and trinuclear nickel species did not show such exceptional behavior. The findings may open a fascinating direction in the field of superatoms to develop new chemical transformations for organometallic chemistry and catalysis. The higher relative stability of binuclear species was also observed in ESI mass spectra of copper and vanadyl complexes with acetylacetonate ligands, Cu2(acac)3 + and (VO)2(acac)3 +. An important point concerns the purity of the studied solutions, since even a trace level of contaminants has drastically diminished the outcome of the mechanistic studies. © 2014 American Chemical Society.

Rekant P.V.,Saint Petersburg State University | Gusev E.A.,Saint Petersburg State University
Russian Geology and Geophysics | Year: 2012

Seismic data on the southern (Laptev Sea) extremity of the Lomonosov Ridge were used to develop a new structural model for the sedimentary cover. It permitted a correlation between the seismic cross-sections of the ridge crest and two deep-sea basins: the Podvodnikov Basin and the Amundsen Plain. It is the first time that a seismic model has taken into account both regional seismic-reflection profiles obtained from NP drifting ice stations and recent high-resolution CDP data. Our seismic model agrees both with geological data on the Laptev Sea continental margin and the data obtained from deep-sea drilling into the Lomonosov Ridge under the IODP-302 project. The sedimentary cover of the southern Lomonosov Ridge and adjacent parts of the Amundsen Plain and Podvodnikov Basin was dated at the Aptian-Cenozoic. The sedimentary section is divided by two main unconformities, of Campanian-Paleocene and Oligocene-Early Miocene ages. The cover contains a structurally complicated graben system, which is an extension of the New Siberian system of horsts and grabens, recognized in the shelf. Sedimentation began in the grabens in the Aptian-Albian and ended with their complete compensation in the Paleocene. © 2012.

Pivinskii Y.E.,OOO NVF Kerambet Ogneupor | Dyakin P.V.,Saint Petersburg State University
Refractories and Industrial Ceramics | Year: 2015

The effect of firing temperature in the range 1000-1350Â°C on indices for shrinkage, porosity, density, and strength of specimens based both fuzed quartz HCBS with different fineness, and cast system with a granular filler based upon them, is studied. Maximum indices for ultimate strength in bending are achieved after firing in the range 1200-1250Â°C. Strength values for different materials are within the limits of 6-9%. With a further increase in firing temperature in spite of an increase in density material strength is reduced as a result of cristobalite formation. It is shown that a fundamental factor governing sintering kinetics is starting fuzed quartz viscosity in the corresponding temperature range. Â© 2015 Springer Science+Business Media New York.

Gulbin Y.L.,Saint Petersburg State University
Geology of Ore Deposits | Year: 2012

The possibility of using a garnet-biotite geothermometer to estimate the nucleation temperature of zoned crystals is considered. The data on the temperature evolution of mineral systems in the course of porphyroblast growth estimated with different methods are compared for a number of metamorphic provinces. The temperatures for garnet core and rim growth calculated by the program THERMOCALC are systematically overestimated compared to those derived using the garnet-biotite geothermometer (Kaneko and Miyano, 2004; Gulbin, 2011a, 2011b). The discrepancy reaches 40-70°C for the isopleth method and 60-90°C for the average PT method. © 2012 Pleiades Publishing, Ltd.

Mironova I.A.,Saint Petersburg State University | Usoskin I.G.,University of Oulu | Kovaltsov G.A.,RAS Ioffe Physical - Technical Institute | Petelina S.V.,La Trobe University
Atmospheric Chemistry and Physics | Year: 2012

Energetic cosmic rays are the main source of ionization of the low-middle atmosphere, leading to associated changes in atmospheric properties. Via the hypothetical influence of ionization on aerosol growth and facilitated formation of clouds, this may be an important indirect link relating solar variability to climate. This effect is highly debated, however, since the proposed theoretical mechanisms still remain illusive and qualitative, and observational evidence is inconclusive and controversial. Therefore, important questions regarding the existence and magnitude of the effect, and particularly the fraction of aerosol particles that can form and grow, are still open. Here we present empirical evidence of the possible effect caused by cosmic rays upon polar stratospheric aerosols, based on a case study of an extreme solar energetic particle (SEP) event of 20 January 2005. Using aerosol data obtained over polar regions from different satellites with optical instruments that were operating during January 2005, such as the Stratospheric Aerosol and Gas Experiment III (SAGE III), and Optical Spectrograph and Infrared Imaging System (OSIRIS), we found a significant simultaneous change in aerosol properties in both the Southern and Northern Polar regions in temporal association with the SEP event. We speculate that ionization of the atmosphere, which was abnormally high in the lower stratosphere during the extreme SEP event, might have led to formation of new particles and/or growth of preexisting ultrafine particles in the polar stratospheric region. However, a detailed interpretation of the effect is left for subsequent studies. This is the first time high vertical resolution measurements have been used to discuss possible production of stratospheric aerosols under the influence of cosmic ray induced ionization. The observed effect is marginally detectable for the analyzed severe SEP event and can be undetectable for the majority of weak-moderate events. The present interpretation serves as a conservative upper limit of solar energetic particle effect upon polar stratospheric aerosols. © 2012 Author(s). CC Attribution 3.0 License.

Zenkevich I.G.,Saint Petersburg State University
Russian Journal of Physical Chemistry A | Year: 2013

It is noted that the pK a values of organic acids can be calculated using the unique recurrence relation pK a(n + 1) = apK a(n) + b from the pK a values of other (usually the simplest and, consequently, better characterized) homologues of the same series. It is shown that this relation is valid within two taxonomic groups: insertion homologues of the ω-substituted acids X(CH2) n CO2H (n ≥ 1) and isomers that differ in the position of substituents X in their alkyl fragments, k-X(C n H2n )CO2H (n ≥ 1, 1 ≤ k ≤ n + 1). It is concluded that this algorithm is a consequence of the unique mathematical properties of recurrence relations. © 2013 Pleiades Publishing, Ltd.

Zenkevich I.G.,Saint Petersburg State University
Russian Journal of General Chemistry | Year: 2013

The values of physicochemical properties determine completely the sequence of chromatographic elution of (Z)- and (E)-isomers of 1,2-disubstituted unsaturated compounds and can therefore be used as reference data for their GC-identification. The isomer with the minimum boiling point, relative density, and refractive index has the least retention parameters. By the ratio of the values of these properties the (Z)- and (E)-isomers form two groups: (Z) > (E) and (Z) < (E). This feature is due to the larger polarity of the (Z)-isomers of asymmetrically substituted compounds containing polar substituents at the double bond C=C. The discovered regularities may be extended to the cis- and trans-isomers of 1,2-disubstituted cycloalkanes and even to the position isomers of substituted arenes. © 2013 Pleiades Publishing, Ltd.

Brusnitsyn A.I.,Saint Petersburg State University | Zhukov I.G.,Russian Academy of Sciences
Ore Geology Reviews | Year: 2012

Recent studies provide an overview on hydrothermal-volcaniclastic-sedimentary manganese deposits from the Magnitigorsk palaeovolcanic belt in Southern Urals, Russia (~. 100 deposits). This report presents data on the structures of ore bodies, chemical composition, and mineralogy of manganese ores. These deposits are divided into two types with different ore-bearing band structures, chemical and mineral ore compositions, and ore component accumulation conditions. Manganese ores of the type 1 deposit are associated with jasperites. Ores from type 2 deposits are localised within thin-banded jaspers. Type 1 deposits are thought to form during hydrothermal activity in areas where hydrothermal fluids leak into the seafloor. Type 2 deposits are formed within a closed basin as hydrothermal activity decreases away from hydrothermal vents, and typically contain a greater volcaniclastic contribution. Manganese ores comprised more than 70 mineral types and form three groups of mineral assemblages: (a) minerals formed during low grade regional metamorphism (T. ≈. 200-260. °C, P. =. 2-3. kbar) that compose the main part of ore bodies, (b) mineral assemblages in segregatic and metasomatic veins filling late stage tectonic fractures, and (c) an assemblage of subsurface supergene minerals. Most of these minerals (which total approximately 38 minerals) are metamorphic silicates. The formation of metamorphic mineral assemblages is controlled by the presence of organic material (OM) in primary sediments. The conditions under which type 1 deposits formed favour the accumulation of OM. The metamorphism of these sediments is responsible for the formation of oxide-carbonate-silicate ("reduced") ores, which consist of Mn-silicates and carbonates (such as tephroite, rhodonite, caryopilite, and rhodochrosite), andradite, quartz, hematite, and hausmannite. Insignificant preserved quantities of OM were found in type 2 deposits. During the metamorphic alteration of these sediments, oxide-silicate ("oxidised") ores were formed with the dominance of braunite. © 2012 Elsevier B.V..

Pavilaynen G.V.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The results for the bending of a cantilever beam with the SD-effect under a concentrated load are discussed. To solve this problem, the standard Bernoulli-Euler hypotheses for beams and the Ilyushin model of perfect plasticity are used. The problem is solved analytically for structural steel A40X. The SD-effect for elastic-plastic deformations is studied. The solutions for beam made of isotropic material and material with the SD-effect are compared. © 2015 AIP Publishing LLC.

Pronina Y.G.,Saint Petersburg State University | Sedova O.S.,Saint Petersburg State University | Kabrits S.A.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The paper compares two analytical solutions for the equal-rate mechanochemical corrosion of an elastic spherical shells subjected to internal and external pressure. Results based on the G. Lame's formulas for a pressurized thick hollow sphere and on the thin-walled spherical shell model are analyzed when applied to relatively thin shells. The rates of corrosion at the inner and outer surfaces are supposed to be proportional to the maximum principal stress at the surface involved. © 2015 AIP Publishing LLC.

Kozlov V.V.,University of Brescia | Kozlov V.V.,Saint Petersburg State University | Wabnitz S.,University of Brescia
Optics Letters | Year: 2010

Lossless polarizers are conservative nonlinear optical devices that transform unpolarized light into highly polarized light without polarization-dependent losses. The device proposed here consists of an up to 100-m-long segment of nonlinear highly birefringent or unidirectionally spun fiber pumped from the output end by an intense backwardpropagating beam. An initially unpolarized (scrambled) signal beam acquires a degree of polarization close to 100% toward the fiber output. © 2010 Optical Society of America.

Rusanov A.I.,Saint Petersburg State University
Colloid Journal | Year: 2016

Specific features of surfactant diffusion in micellar systems are described in terms of mobility, i.e., the limiting velocity of a particle under the action of a unit force. Micellar solutions of nonionic and ionic surfactants are analyzed. A relation is established between average surfactant mobility and the mobilities of individual particles. Although micelles have a lower mobility than monomers have, the average mobility of surfactants is shown to increase rather than decrease upon micellization. In parallel, formulas describing diffusion coefficients are derived, with part of the formulas having been available in the literature. © 2016, Pleiades Publishing, Ltd.

Malkin Z.,Saint Petersburg State University
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2016

The Allan variance (AVAR) was introduced 50 years ago as a statistical tool for assessing the frequency standards deviations. For the past decades, AVAR has increasingly been used in geodesy and astrometry to assess the noise characteristics in geodetic and astrometric time series. A specific feature of astrometric and geodetic measurements, as compared with clock measurements, is that they are generally associated with uncertainties; thus, an appropriate weighting should be applied during data analysis. In addition, some physically connected scalar time series naturally form series of multidimensional vectors. For example, three station coordinates time series X, Y, and Z can be combined to analyze 3-D station position variations. The classical AVAR is not intended for processing unevenly weighted and/or multidimensional data. Therefore, AVAR modifications, namely weighted AVAR (WAVAR), multidimensional AVAR (MAVAR), and weighted multidimensional AVAR (WMAVAR), were introduced to overcome these deficiencies. In this paper, a brief review is given of the experience of using AVAR and its modifications in processing astrogeodetic time series. © 2015 IEEE.

Afonin S.S.,Saint Petersburg State University
International Journal of Modern Physics A | Year: 2010

In the usual holographic approach to QCD, the meson spectrum is generated due to a nontrivial five-dimensional background. We propose an alternative five-dimensional scenario in which the spectrum emerges due to coupling to a scalar field whose condensation is supposed to be dual to the formation of gluon condensate and mimics the scale anomaly in QCD. The spectrum of model has finite number of discrete states plus continuum and reveals a Regge-like behavior in the strong coupling regime. © 2010 World Scientific Publishing Company.

Vainola R.,University of Helsinki | Strelkov P.,University of Helsinki | Strelkov P.,Saint Petersburg State University
Marine Biology | Year: 2011

From data on allozyme, nuclear DNA and mitochondrial DNA markers, we show that the originally North Pacific/Northwest Atlantic mussel Mytilus trossulus is widespread on North European coasts, earliM. trossuluser thought to be inhabited only by Mytilus edulis. Several local occurrences of, interspersed with a dominant M. edulis, were recorded on the North Sea, Norwegian Sea and Barents Sea coasts of Norway and the Barents and White Sea coasts of Kola Peninsula in Russia. The proportion of M. trossulus genetic background observed at any one site varied from 0 to 95%. These new occurrences are not related to the previously known, introgressed M. trossulus population that occupies the Baltic Sea. The new northern occurrences retain both the F and M M. trossulus mitochondria, which have been lost from the Baltic stock. While hybridization takes place wherever M. trossulus and M. edulis meet, the extent of hybrization varies between the different contact areas. Hybrids are rare, and the hybrid zones are bimodal in the northern areas; more interbreeding has taken place further south in Norway, but even there genotypic disequilibria are higher than those in the steep transition zone between the Baltic mussel and M. edulis: there is no evidence of a collapse toward a hybrid swarm unlike in the Baltic. The Barents and White Sea M. trossulus are genetically slightly closer to the NW Atlantic than NE Pacific populations, while the Baltic mussel has unique features distinguishing it from the others. We postulate that the presence of M. trossulus in Northern Europe is a result of repeated independent inter- or transoceanic cryptic invasions of various ages, up to recent times. © 2011 The Author(s).

Afonin S.S.,Saint Petersburg State University
International Journal of Modern Physics A | Year: 2010

The AdS/QCD models are known to be closely related to the QCD sum rules in the large-Nc (called also planar) limit. Rewriting the theory of infinite tower of free stable mesons expected in the large-Nc QCD as a five-dimensional theory, we scrutinize to what extend the bottom-up holographic models may be viewed as an alternative language expressing the phenomenology of planar QCD sum rules. It is found that many features of AdS/QCD models can be thereby obtained without invoking prescriptions from the original AdS/CFT correspondence. Under some assumptions, all possibilities leading to simple Regge trajectories are classified, and it is argued that the most phenomenologically consistent model is the one called "soft wall model" in the holographic approach, with a preference to the positive-sign dilaton background. © 2010 World Scientific Publishing Company.

Solovyev D.,Saint Petersburg State University | Labzowsky L.,Saint Petersburg State University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

A rigorous quantum electrodynamics theory of the multiphoton decay of excited states in a hydrogen atom is presented. The "two-photon" approximation is formulated which is limited by the one- and two-photon transitions including cascade transitions with two-photon links. This may be helpful for the strict description of the recombination process in a hydrogen atom and, in principle, for the history of hydrogen recombination in the early universe. © 2010 The American Physical Society.

Chashnikova V.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

In this paper sufficient conditions of identifiability for a linear dynamic system with unknown matrix and control vector are proved. Then for the identified matrix and the vector sufficient conditions of controllability are established. These conditions depend on measuring errors and eigenvalues of matrix. © 2015 AIP Publishing LLC.

Kvitko A.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

An algorithm is proposed for constructing a control function that transfer wide class of nonlinear systems of ordinary differential equations from an initial state to an fixed state. The algorithm is convenient for numerical implementation. A constructive condition is obtained for which this transfer is possible. © 2015 AIP Publishing LLC.

Zolotova N.V.,Saint Petersburg State University | Ponyavin D.I.,Saint Petersburg State University
Astrophysical Journal | Year: 2011

In this paper, the problem of the unusually long 4th sunspot cycle is discussed: was the length of this cycle exceptionally large or really composed of two short cycles? Analyzing the latitude-time diagram in 1784-1798, reconstructed from the drawings by Staudacher, Hamilton, and Gimingham, we suggest that the 4th cycle length can be a result of an impulse of activity in the northern hemisphere during the descending phase. The local minimum in 1793 can be just a gap between impulses of the solar activity, similar to the declining phase in the southern hemisphere of the long cycle 20. The long declining phase of cycle 4 is that the minimum in 1793 may also be due to lack of data. We have shown that sparse observations of the sunspots, in the second half of cycle 4, do not prove the existence of the "lost" tiny cycle from 1793 to 1800. © 2011. The American Astronomical Society. All rights reserved.

Marscher A.P.,Boston University | Jorstad S.G.,Boston University | Jorstad S.G.,Saint Petersburg State University
Astrophysical Journal | Year: 2011

We present an X-ray image of the BL Lacertae (BL Lac) object OJ287 revealing a long jet, curved by 55° and extending 20″ or 90kpc from the nucleus. This de-projects to >1Mpc based on the viewing angle on parsec scales. Radio emission follows the general X-ray morphology but extends even farther from the nucleus. The upper limit to the isotropic radio luminosity, 2 × 1024WHz-1, places the source in the Fanaroff-Riley 1 (FR 1) class, as expected for BL Lac objects. The spectral energy distribution indicates that the extended X-ray emission is from inverse Compton scattering of cosmic microwave background photons. In this case, the derived magnetic field is B 5 μG, the minimum electron energy is 7-40m e c 2, and the Doppler factor is δ 8 in a knot 8″ from the nucleus. The minimum total kinetic power of the jet is (1-2)×10 45ergs-1. Upstream of the bend, the width of the X-ray emission in the jet is about half the projected distance from the nucleus. This implies that the highly relativistic bulk motion is not limited to an extremely thin spine, as has been proposed previously for FR 1 sources. The bending of the jet, the deceleration of the flow from parsec to kiloparsec scales, and the knotty structure can all be caused by standing shocks inclined by 7° to the jet axis. Moving shocks resulting from major changes in the flow properties can also reproduce the knotty structure, but such a model does not explain as many of the observational details. © 2011. The American Astronomical Society. All rights reserved.

Kuzmin A.,University of Latvia | Kalinko A.,University of Latvia | Evarestov R.A.,Saint Petersburg State University
Acta Materialia | Year: 2013

The electronic, structural and phonon properties of antiferromagnetic triclinic CuWO 4 have been studied using the first-principles spin-polarized linear combination of atomic orbital (LCAO) calculations based on the hybrid exchange-correlation density functional (DFT)/Hartree-Fock (HF) scheme. In addition, the local atomic structure around both Cu and W atoms has been probed using extended X-ray absorption fine structure (EXAFS) spectroscopy. We show that, by using the hybrid DFT-HF functional, one can accurately and simultaneously describe the atomic structure (the unit cell parameters and the atomic fractional coordinates), the band gap and the phonon frequencies. In agreement with our EXAFS results, the LCAO calculations reproduce a strong distortion of both the CuO 6 and the WO 6 octahedra, which occur due to the first-order and second-order Jahn-Teller effects, respectively. We found that the HF admixture of 13-16%, which is implemented in the PBE0-13% and WCGGA-PBE-16% functionals, produces the best result for CuWO 4. The calculated properties agree well with the available experimental data provided by diffraction, optical, X-ray photoelectron and Raman spectroscopies. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Rusanov A.I.,Saint Petersburg State University
Russian Chemical Reviews | Year: 2016

As materials science studies physicochemical properties of materials, it needs a support of thermodynamics, which predicts general regularities for physicochemical properties of matter. This survey deals with solid materials the thermodynamic description of which is especially complicated. The achievements of last years provide better insight in the chemical potential anisotropy and, on this grounding, in the anisotropy of chemical affinity governing all processes in solid materials. The survey summarizes novel approaches and thermodynamic equations and then exhibits their use in materials science. As examples, the solubility, creep and corrosion of materials are analyzed. A newly discovered phenomenon, the strain sign effect in corrosion under stress (e.g., a difference in the corrosion rate on the opposite sides of a bent metallic plate), is described and explained thermodynamically.Amodern theory of the strength of materials developed during last years is also presented with the characterization of crack properties, the mechanisms of crack propagation and estimation of the ultimate stress. The development of this area required the introduction of a novel thermodynamic potential that formed the basis for the theory of strength. © 2015 Russian Academy of Sciences and Turpion Ltd.

Moskvin L.N.,Saint Petersburg State University
Separation and Purification Reviews | Year: 2016

A general classification of separation methods is attempted. The two criteria were phase transformations and interfacial transfers. All separation methods of homogenous mixtures were divided into five groups: (i) methods that are based on the formation of new phases by substances to be separated; (ii) methods that are based on differences in the interphase distribution processes, chromatographic methods being singled out as a separate group; (iii) membrane methods that are based on induced transfers of substances from one phase into another one across a third phase, which separates the two; (iv) separation methods within a single phase that are based on velocity and direction differences in spatial displacement of particles of substances to be separated within one fluid phase under the action of various fields; and (v) combined methods working combining previously listed methods. Descriptions of each group of separation methods include their intragroup classification and information on the most important techniques as well as the least known of them. These descriptions are in the form of reviews of fundamental and most important publications, regardless of the time they appeared. For the well-known classical methods of the first group all necessary information can be found in university textbooks. Copyright © 2016 Taylor & Francis Group, LLC.

Stolyarova V.L.,Saint Petersburg State University
Russian Chemical Reviews | Year: 2016

Progress in methods of synthesis of advanced materials as well as utilization of such materials at high temperatures requires information on the vaporization processes and thermodynamic properties of oxide systems. The optimal experimental method for these purposes is high-temperature mass spectrometry. This review summarizes and classifies experimental results obtained in mass spectrometric studies of the high-temperature thermodynamic properties of oxide systems and materials carried out in the last two decades. Published data on the vaporization processes and thermodynamic properties of oxide materials for high-temperature technologies are discussed from the standpoint of acid - base concept and model approaches including statistical thermodynamic methods. The bibliography includes 248 references. © 2015 Russian Academy of Sciences and Turpion Ltd.

Yakusheva D.B.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The method for constructing discrete control functions guaranteing that solutions of nonlinear systems of ordinary differential equations join given points in the phase space is developed. The goal is achieved by reducing the original problem to stabilization of linear nonstationary system of a special kind and solving the Cauchy problem for the auxiliary system of ordinary differential equations. The efficiency of the algorithm is illustrated by numerical simulation of specific practical problem. © 2015 AIP Publishing LLC.

Filippov S.B.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

Buckling of a thin elastic cylindrical shell stiffened by rings of rectangular cross-sections are considered. The parameters of the shell of the minimal weight, having a given critical external pressure, are found. For the evaluating of the optimal parameters the asymptotic approach is used. © 2015 AIP Publishing LLC.

Nikiforov K.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The software complex developed in MATLAB allows modelling of function of diode and triode structures based on field emission electron sources with complex sub-micron geometry, their volt-ampere characteristics, calculating distribution of electric field for educational and research needs. The goal of this paper is describing the physical-mathematical model, calculation methods and algorithms the software complex is based on, demonstrating the principles of its function and showing results of its work. For getting to know the complex, a demo version with graphical user interface is presented. © 2015 AIP Publishing LLC.

Sedova O.S.,Saint Petersburg State University | Pronina Y.G.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The paper considers the double-sided uniform corrosion of an elastic spherical shell under internal and external pressure. It is assumed that corrosion rates are piecewise linear functions of maximum principal stress at the related surface. Analytical solution for the problem is provided. Some examples are given. © 2015 AIP Publishing LLC.

Andrianov S.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The work deals with the construction of strategy for finding optimal control of systems for spatially distributed systems on an example of problems in physics beams. The suggested approach is based on use of exact and approximate invariants as a controlling mechanism for control of modelling process of beam lines. The classical problem of optimal control of similar systems as an optimal control problem is formulated in a functional space. This approach is based on algebraic methods Lie and the corresponding matrix formalism that allows you to build not only the formal procedures for finding optimal solutions, but also provide the necessary constructive computational procedures. © 2015 AIP Publishing LLC.

Alferov G.V.,Saint Petersburg State University | Malafeyev O.A.,Saint Petersburg State University | Maltseva A.S.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

In this paper we formalize and study two game-theoretic models of the process of inspection and intercept. In the first model a pursuer ship of anti-corruption group equipped with sonar, searches and interception adversary submarine (which may be a terrorist, corrupt, drug dealer group). In the second model, the pursuer, carrying n boats j=l,2 ⋯ n with depth charges on board at time t0 spotted at various distances from itself on the sea surface periscopes of n submarines i=l,2 ⋯ n, which at the same time falling under the water with fixed velocities and moving in straight lines in different directions. © 2015 AIP Publishing LLC.

Kabrits S.A.,Saint Petersburg State University | Kolpak E.P.,Saint Petersburg State University
AIP Conference Proceedings | Year: 2015

The article is devoted to numerical study of convergence of calculation results obtained on the basis of two nonlinear models of the theory of shells with thickness decrease. As models are considered nonlinear theory of thin shells, based on the hypotheses of the Kirchhoff-Chernykh and hypotheses type Tymoshenko, modified K.F. Chernykh for the case of hyperelastic rubber-like material. As an example, we consider the problem of axisymmetric conical compression and spherical shell by axial force. The convergence of results with decreasing thickness is disturbed in areas stability loss(buckling). Also happens when in the deformation process is violated the basic assumption of the theory of shells - the thickness is much smaller than radius of curvature (h < < R). © 2015 AIP Publishing LLC.

Pevzner L.M.,Saint Petersburg State University
Russian Journal of General Chemistry | Year: 2015

Bromination of ethyl 4-(diethoxyphosphorylmethyl)-5-methylfuran-2-carboxylate and 4-(diethoxyphosphorylmethyl)-5-methylfuran-2-carbonitrile with N-bromosuccinimide followed by phosphorylation via the Arbuzov reaction have yielded the corresponding 2-substituted 4,5-bis(diethoxyphosphorylmethyl)furans. Synthesis and transformations of bisphosphorylated 2-furoic acid and its derivatives are described. © 2015 Pleiades Publishing, Ltd.

Evsyukova H.V.,Saint Petersburg State University
European Journal of Clinical Investigation | Year: 2011

Background The diffuse neuroimmunoendocrine system (DNIES) is a universal system of response, control and organism protection. Platelets are cells of DNIES producing and storing melatonin which plays an important role in the regulation of physiological processes in the human body, under normal conditions and in pathology. Our previous study has revealed a low basic melatonin production in patients with aspirin-induced asthma (AIA). It has been suggested that low daytime production of melatonin in patients with AIA is attributable to the reduction in its synthesis in platelets in this group of patients. The objective of this study was to investigate this hypothesis. Materials and methods The melatonin expression in platelets has been studied by means of indirect immunofluorescence in nine patients with AIA and 14 healthy subjects. Results The results of the study have revealed that only 13·1±1·3% of platelets in patients with AIA have shown melatonin-specific luminescence, compared to 97·7±0·6% of platelets in healthy subjects (P<0·001). No melatonin expression has been observed in the rest of platelets in patients with AIA. No significant difference between the degree of the melatonin luminescence in platelets of the patients with AIA and control group has been found. Conclusions It can be concluded that the reduced melatonin synthesis in platelets of patients with AIA may determine a low daytime melatonin production and may lead to impairments in platelet receptors and ion channels. This results in disturbances in calcium homoeostasis, which may be a cause of platelet activation and pathological response to exogenous melatonin and acetylsalicylic acid. © 2011 The Author. European Journal of Clinical Investigation © 2011 Stichting European Society for Clinical Investigation Journal Foundation.

Vassilevich D.V.,Federal University of ABC | Vassilevich D.V.,Saint Petersburg State University
Classical and Quantum Gravity | Year: 2010

It is well known that for a given Poisson structure one has infinitely many star products related through the Kontsevich gauge transformations. These gauge transformations have an infinite functional dimension, corresponding to an infinite number of degrees of freedom per point of the base manifold. We show that on a symplectic manifold this freedom may be almost completely eliminated if one extends the star product to all tensor fields in a covariant way and impose some natural conditions on the tensor algebra. The remaining ambiguity corresponds either to constant renormalizations to the symplectic structure, or to maps between classically equivalent field theory actions. We also discuss how one can introduce the Riemannian metric in this approach and the consequences of our results for noncommutative gravity theories. © 2010 IOP Publishing Ltd.

Zenkevich I.G.,Saint Petersburg State University
Journal of Chemometrics | Year: 2014

The series of substituted alkanecarboxylic acids including insertion homologues of ω-substituted acids X(CH2)nCO2H (n≥1) and isomers that differ in the position of substituents X in the alkyl fragments, k-X(CnH2n)CO2H (n=const≥1, 1≤k≤n+1) is the sub-group most poorly characterized by their acidity constants, pKa, comparing with the acids of the other sub-groups. When the experimental data for such compounds are unavailable, the precalculated estimates should be taken into consideration. The pKa values for such acids can be calculated using the single first-order recurrent relation, pKa(n+1)=apKa(n)+b, using pKa values of other (usually the simpler and, consequently, better characterized) homologues and/or isomers of the same series. This algorithm results from the unique mathematical properties of recurrent relations in chemistry. © 2014 John Wiley & Sons, Ltd.

Baluev R.V.,Saint Petersburg State University
Astronomy and Computing | Year: 2013

We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation.Its major abilities include: (i) advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV jitter; (ii) user-friendly multi-Keplerian as well as Newtonian N-body RV fits; (iii) use of more efficient maximum-likelihood periodograms that involve the full multi-planet fitting (sometimes called as "residual" or "recursive" periodograms); (iv) easily calculatable parametric 2D likelihood function level contours, reflecting the asymptotic confidence regions; (v) fitting under some useful functional constraints is user-friendly; (vi) basic tasks of short- and long-term planetary dynamical simulation using a fast Everhart-type integrator based on Gauss-Legendre spacings; (vii) fitting the data with red noise (auto-correlated errors); (viii) various analytical and numerical methods for the tasks of determining the statistical significance.It is planned that further functionality may be added to PlanetPack in the future. During the development of this software, a lot of effort was made to improve the calculational speed, especially for CPU-demanding tasks. PlanetPack was written in pure C++ (standard of 1998/2003), and is expected to be compilable and useable on a wide range of platforms. © 2013 Elsevier B.V.

Zherlitsyn G.,Saint Petersburg State University | Matveev A.S.,Saint Petersburg State University
Automatica | Year: 2010

The paper considers a sensor network whose sensors observe a common quantity and are affected by arbitrary additive bounded noises with a known upper bound. During the experiment, any sensor can communicate only a finite and given number of bits of information to the decision center. The contributions of the particular sensors, the rules of data encoding, decoding, and fusion, as well as the estimation scheme should be designed to achieve the best overall performance in estimation of the observed quantity by the decision center. An optimal algorithm is obtained that minimizes the maximal feasible error. It is shown that it considerably outperforms the algorithm proposed in recent papers in the area and examined only in the idealized case of noiseless sensors. © 2010 Elsevier Ltd. All rights reserved.

Ovid'ko I.A.,Saint Petersburg State University | Sheinerman A.G.,Russian Academy of Sciences
European Journal of Mechanics, A/Solids | Year: 2012

A theoretical model is suggested which describes generation and growth of nanoscale cracks (nanocracks) near tips of blunt cracks in nanocrystalline solids. Within the model, stress concentration near pre-existent/growing blunt cracks induces grain boundary sliding which leads to formation of dislocations at triple junctions of grain boundaries. The superposition of the external stress concentrated near tips of blunt cracks and stresses created by these dislocations is capable of initiating generation and growth of nanocracks. The characteristics of the nanocrack generation and growth in nanocrystalline Al and α-Fe are calculated, and the effects of these processes on toughness/ductility of nanocrystalline solids are discussed. © 2011 Elsevier Masson SAS. All rights reserved.

Miroshnichenko G.P.,Saint Petersburg State University
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2012

A phenomenological Hamiltonian of photons in a single-mode stochastic inhomogeneous optical fiber (OF) is derived. Quantization of radiation is performed in the basis of an ideal OF with proper calibration that ensures transversality of the electric-field-displacement vector. Stochastic parameters of the Hamiltonian are determined by using the reciprocal tensor of the dielectric permittivity averaged over the OF segment volume. The Hamiltonian is parametrized by three phenomenological parameters and preserves the number of photons. It is assumed that the segment of the OF is divided into random subsegments with optical parameters defined by the Wiener process with respect to the longitudinal coordinate. The temporal dynamics of the single-photon density matrix is analyzed in the basis of states with orthogonal polarizations. The relative quantum beat error rate in the sifted quantum key distributed according to the BB84 protocol with polarization coding of information averaged over the scatter of the OF parameters is calculated. © Pleiades Publishing, Ltd., 2012.

Ovid'ko I.A.,Saint Petersburg State University | Sheinerman A.G.,Saint Petersburg State University
Journal of Physics D: Applied Physics | Year: 2012

A special physical micromechanism of plastic flow in pre-cracked nanocrystalline solids is suggested and theoretically described. The micromechanism represents the fast nanoscale rotational deformation (NRD) occurring through collective events of ideal nanoscale shear near crack tips. We calculated the stress and energy characteristics of the NRD. It has been found that such rotational deformation can effectively occur near crack tips and enhance fracture toughness of nanocrystalline materials. Our theoretical model accounts for the in situ experimental observations (Ke et al 1995 Nanostruct. Mater. 5 689, Shan et al 2008 Phys. Rev. Lett. 100 105502, Cheng et al 2010 Phys. Rev. Lett. 104 255501, Liu et al 2011 Scripta Mater. 64 343) of crystal lattice rotations within nanoscale grains and formation of modulated/ agglomerated grain structures near crack tips in deformed nanocrystalline solids with finest grains. © 2012 IOP Publishing Ltd.

Ovid'Ko I.A.,Saint Petersburg State University
Reviews on Advanced Materials Science | Year: 2012

Conventional curved carbon nanostructures such as fullerenes, capped nanotubes and cones can be produced by insertion of pentagons-sources of highly concentrated curvature - Into initially flat hexagonal lattice of single crystalline graphene. This paper is focused on a new approach (suggested and biefly discussed earlier [I.A. Ovid'ko II Rev. Adv. Mater. Sci. 30 (2012) 201]) which potentially allows one to fabricate principally new curved carbon nanostructures with arbitrary geometries/shapes. The approach represents insertion of special defects into grain boundaries (GBs) of initially flat polycrystalline graphene. Since special defects typically serve as flexible sources of weakly concentrated curvature, this approach opens intriguing possibilities to fabricate new carbon nanostructures with novel properties controlled by their curvature. In particular, elastic strains created by weakly varying curvature in polycrystalline graphene can effectively tailor its electronic properties and thus be exploited in electronics based on design of moderately curved graphene. Also, in this paper, technological schemes/strategies are outlined which can be potentially exploited in the fabrication of new curved carbon nanostructures through GB engineering in graphene. © 2012 Advanced Study Centre Co. Ltd.

Ovid'Ko I.A.,Saint Petersburg State University | Skiba N.V.,Saint Petersburg State University
Scripta Materialia | Year: 2012

A new mechanism for enhanced dislocation emission from grain boundaries (GBs) in deformed nanocrystalline (NC) materials is suggested and theoretically described. The dislocation emission is highly enhanced by intergrain sliding (or stress-driven GB migration) and occurs in directions approximately perpendicular to GB planes, in contrast to its conventional counterpart occurring in directions approximately parallel with GBs that carry intergrain sliding. The energy and stress characteristics of the enhanced dislocation emission in NC aluminum and NC silicon carbide are calculated. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Syromyatnikov A.V.,Saint Petersburg State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We discuss spin-12 one-dimensional (1D) and quasi-1D magnets with competing ferromagnetic nearest-neighbor J 1 and antiferromagnetic next-nearest-neighbor J exchange interactions in a strong magnetic field H. It is well known that, due to attraction between magnons, quantum phase transitions (QPTs) take place at H=H s from the fully polarized phase to the nematic phase if J>|J 1|/4. Such a transition at J>0.368|J 1| is characterized by a softening of the two-magnon bound-state spectrum. Using a bond-operator formalism we propose a bosonic representation of the spin Hamiltonian containing, aside from bosons describing one-magnon spin-1 excitations, a boson describing spin-2 excitations whose spectrum coincides at H≥H s with the two-magnon bound-state spectrum obtained before. The presence of the bosonic mode in the theory that softens at H=H s makes the QPT consideration substantially standard. In the 1D case at H

Ovid'Ko I.A.,Saint Petersburg State University
Scripta Materialia | Year: 2012

Crystals are conventionally treated to be deformed through generation and evolution of crystal lattice defects. In this paper, nanoscale amorphization (NA; formation of nanoscale amorphous regions in crystals under mechanical load) is suggested and theoretically described as a special/alternative deformation mode operating in crystalline solids. It is shown that NA can contribute effectively to plastic flow in crystalline Ni and Si nanowires. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Sushko P.V.,University College London | Sushko P.V.,Tohoku University | Abarenkov I.V.,Saint Petersburg State University
Journal of Chemical Theory and Computation | Year: 2010

We present a method and a computer code for accurate calculation of electrostatic potential in an arbitrary crystalline lattice modeled using a finite system. The method is based on complementing a lattice unit cell with a set of point charges in order to annihilate simultaneously all components of any number of the lowest multipole moments. The positions and the values of the complementary charges are determined analytically. The electrostatic potential produced by each modified cell is short range, and the corresponding lattice series converges absolutely, which makes it convenient to use in embedded cluster calculations of solids, surfaces, and low-dimensional structures. The method is illustrated by application to the rutile TiO 2 and α-quartz SiO 2 lattices and to those of several complex minerals. © 2010 American Chemical Society.

Lejzerowicz F.,University of Geneva | Voltsky I.,Saint Petersburg State University | Pawlowski J.,University of Geneva
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2013

Metagenetics represents an efficient and rapid tool to describe environmental diversity patterns of microbial eukaryotes based on ribosomal DNA sequences. However, the results of metagenetic studies are often biased by the presence of extracellular DNA molecules that are persistent in the environment, especially in deep-sea sediment. As an alternative, short-lived RNA molecules constitute a good proxy for the detection of active species. Here, we used a metatranscriptomic approach based on RNA-derived (cDNA) sequences to study the diversity of the deep-sea benthic foraminifera and compared it to the metagenetic approach. We analyzed 257 ribosomal DNA and cDNA sequences obtained from seven sediments samples collected in the Sea of Japan at depths ranging from 486 to 3665. m. The DNA and RNA-based approaches gave a similar view of the taxonomic composition of foraminiferal assemblage, but differed in some important points. First, the cDNA dataset was dominated by sequences of rotaliids and robertiniids, suggesting that these calcareous species, some of which have been observed in Rose Bengal stained samples, are the most active component of foraminiferal community. Second, the richness of monothalamous (single-chambered) foraminifera was particularly high in DNA extracts from the deepest samples, confirming that this group of foraminifera is abundant but not necessarily very active in the deep-sea sediments. Finally, the high divergence of undetermined sequences in cDNA dataset indicate the limits of our database and lack of knowledge about some active but possibly rare species. Our study demonstrates the capability of the metatranscriptomic approach to detect active foraminiferal species and prompt its use in future high-throughput sequencing-based environmental surveys. © 2012 Elsevier Ltd.

Usoskin I.G.,University of Oulu | Kovaltsov G.A.,RAS Ioffe Physical - Technical Institute | Mironova I.A.,Saint Petersburg State University
Journal of Geophysical Research: Atmospheres | Year: 2010

A new version of the CRAC:CRII model computing ionization induced by cosmic rays in the atmosphere is presented, which is extended to the upper atmosphere and can be now applied to the entire atmosphere. The model is able to compute the ionization rate in the atmosphere at any given location and time provided the energy spectrum of incoming cosmic rays is known. It is discussed that the use of earlier models, either analytical or Monte Carlo, with the limited upper energy of 500 MeV, is well validated for the upper atmosphere (above a few g/cm2 atmospheric depth, which corresponds to the altitude about 40 km) to study the effect of solar energetic particles but may lead to a significant underestimate of the background ionization due to galactic cosmic rays. The use of a full model accounting for the atmospheric cascade and full energy range of incoming cosmic rays, rather than earlier simplified models, is recommended to study the ionization effects of galactic cosmic rays in the upper atmosphere. On the other hand, transient strong effects of solar energetic particle events can be studied using truncated models. Copyright 2010 by the American Geophysical Union.

Tsyganenko N.A.,Saint Petersburg State University
Journal of Geophysical Research: Space Physics | Year: 2010

Four data-based models of the magnetospheric magnetic field were tested for the degree of their consistency with a static balance between the magnetic and plasma stresses. To that end, best fit distributions of the plasma sheet pressure and its anisotropy were derived in the midnight meridian plane, using two specific forms of the particle distribution function. The tailward limit of the modeling region was placed at R = 20 RE, where the condition of pressure balance with the tail lobe field was used to avoid the multiplicity of solutions of the force balance equation. Best fit solutions were derived by minimizing the rms difference between the magnetic and plasma stress vectors over a set of points within the model plasma sheet at distances 5 R 20 R E. The obtained equatorial profiles of P⊥ and P ∥ demonstrate a steep decrease of both pressures from the inner to outer boundary and a strong overall increase from quiet to disturbed conditions. The anisotropy ratio = P∥/P⊥ was found to significantly deviate from unity in the case of TU82 and T87 models, with progressively higher values of at larger tailward distances. By contrast, more recent T89 and T96 models yielded more realistic results with nearly isotropic pressure in the tail and a moderate pancake-type anisotropy in the inner magnetosphere, consistent with observations. © 2010 by the American Geophysical Union.

Kulabukhova N.,Saint Petersburg State University
IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference | Year: 2013

High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictorcorrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.

Abakumov E.V.,Saint Petersburg State University
Eurasian Soil Science | Year: 2010

The particle-size distribution in soils sampled near Russian polar stations in West Antarctica has been studied. It is shown that the soils of the Subantarctic zone (the Bellingshausen Station on King George Island) are characterized by a higher content of silt and clay in the fine earth fraction and by a higher content of the fine earth fraction in comparison with the soils of the proper Antarctic tundra barrens near the Lenin-gradskaya Station and the Antarctic cold desert near the Russkaya Station. In the latter soils, the content of rock fragments is higher than that in the soils of the Antarctic tundra barrens. In the soils of the tundra barrens, a considerable accumulation of fine earth may take place in large cavities (hollows) on the stony bedrock surface. Desert pavements are formed in both types of Antarctic landscapes. © Pleiades Publishing, Ltd. 2010.

Abakumov E.V.,Saint Petersburg State University
Eurasian Soil Science | Year: 2010

Original data on humus-forming substances and their elemental and biochemical compositions in Antarctic soils are discussed. Mosses, lichens, algae, remains of higher vascular plants, and penguin guano of two types differ considerably in their chemical compositions. This leads to significant differences in the formation of humic substances in plant materials themselves in the course of their transformation. However, no significant differences in the composition of humus in the fine earth of soils developing under different humus-forming materials have been revealed, which may be related to the extremely low rates of humification. Significant differences between the soils of Antarctic landscapes proper and the soils of the Subantarctic King George Island are only observed in the humus enrichment with nitrogen. The soils of Antarctica are low-humus soils with the humate-fulvate or fulvate types of humus. © 2010 Pleiades Publishing, Ltd.

Biske Yu.S.,Saint Petersburg State University | Seltmann R.,Natural History Museum in London
Gondwana Research | Year: 2010

The Upper Paleozoic orogenic belt of South Tian-Shan (STS) in Kyrgyzstan, Uzbekistan and Tajikistan consists of two structural domains: the south-vergent Bukantau-Kokshaal (BK) in the north and continuing into Xinjiang (China), and the north-vergent Zeravshan-Hissar (ZH) in the south, in Tajikistan. The Bukantau-Kokshaal fold belt was thrust south onto the Kyzylkum-Alai and Tarim continents in the Late Carboniferous. The BK belt is the most prominent collision-related, alpine-type part of the Paleozoic Tian-Shan and, as a prolongation of the Tian-Shan structure, shows close resemblance to the western (outer, west-vergent) part of the Urals. The Kazakhstan continent acts as a hinterland to the BK collision belt. Kazakhstan was constructed by accretion processes in which ancient (presumably Gondwanan) continental terranes and ocean-derived crustal elements of the Early Paleozoic to Early Carboniferous age played a role. The main episode of terrane amalgamation took place during the Middle and Late Ordovician. This appears to reflect active margin development in the Paleoasiatic Ocean, and resembles processes occurring in the recent Western Pacific. Geological differences in construction and protolith age of continental crust in the region are in general agreement with Pb- and Sm-Nd isotopic data. Relatively early (Visean) north-vergent thrust structures in Zeravshan-Hissar and eastern Alai (southwestern STS) bear some resemblance to the Central European Hercynides of Rheic origin, although this region became the location of active margin tectonic processes associated with the closure of the Paleotethys Ocean during the Carboniferous. Post-collisional magmatism occurred from ca. 300 to 270 Ma and is represented by a variety of magma types from A-type granites to nepheline syenites. The spatial distribution of plutons appears to be controlled by transtensional structures associated with east-west, left-lateral wrench faulting. The presence of coeval alkali intrusions and plateau basalts in adjacent areas suggests that this magmatism may have been associated with a mantle plume. Crown Copyright © 2009.

Zaitsev A.N.,Saint Petersburg State University