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.
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.
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.
Noskov B.A.,Saint Petersburg State University
Advances in Colloid and Interface Science | Year: 2014
Experimental results on the dynamic dilational surface elasticity of protein solutions are analyzed and compared. Short reviews of the protein behavior at the liquid-gas interface and the dilational surface rheology precede the main sections of this work. The kinetic dependencies of the surface elasticity differ strongly for the solutions of globular and non-globular proteins. In the latter case these dependencies are similar to those for solutions of non-ionic amphiphilic polymers and have local maxima corresponding to the formation of the distal region of the surface layer (type I). In the former case the dynamic surface elasticity is much higher (> 60 mN/m) and the kinetic dependencies are monotonical and similar to the data for aqueous dispersions of solid nanoparticles (type II). The addition of strong denaturants to solutions of bovine serum albumin and β-lactoglobulin results in an abrupt transition from the type II to type I dependencies if the denaturant concentration exceeds a certain critical value. These results give a strong argument in favor of the preservation of the protein globular structure in the course of adsorption without any denaturants. The addition of cationic surfactants also can lead to the non-monotonical kinetic dependencies of the dynamic surface elasticity indicating destruction of the protein tertiary and secondary structures. The addition of anionic surfactants gives similar results only for the protein solutions of high ionic strength. The influence of cationic surfactants on the local maxima of the kinetic dependencies of the dynamic surface elasticity for solutions of a non-globular protein (β-casein) differs from the influence of anionic surfactants due to the heterogeneity of the charge distribution along the protein chain. In this case one can use small admixtures of ionic surfactants as probes of the adsorption mechanism. The effect of polyelectrolytes on the kinetic dependencies of the dynamic surface elasticity of protein solutions is weaker than the effect of conventional surfactants but exceeds the error limits. © 2013 Elsevier B.V.
Krivovichev S.V.,Saint Petersburg State University
Angewandte Chemie - International Edition | Year: 2014
The discovery of the diffraction of X-rays on crystals opened up a new era in our understanding of nature, leading to a multitude of striking discoveries about the structures and functions of matter on the atomic and molecular scales. Over the last hundred years, about 150 000 of inorganic crystal structures have been elucidated and visualized. The advent of new technologies, such as area detectors and synchrotron radiation, led to the solution of structures of unprecedented complexity. However, the very notion of structural complexity of crystals still lacks an unambiguous quantitative definition. In this Minireview we use information theory to characterize complexity of inorganic structures in terms of their information content. Cause and complexity: Analysis of inorganic crystal structures using information-based complexity measures indicates that structural complexity is generated by the assembly of nanoscale building blocks, modularity induced by complex chemical compositions, and the formation of superlattices as a result of local atomic ordering or displacive phase transitions. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Toukach F.V.,RAS N. D. Zelinsky Institute of Organic Chemistry |
Ananikov V.P.,Saint Petersburg State University
Chemical Society Reviews | Year: 2013
All living systems are comprised of four fundamental classes of macromolecules-nucleic acids, proteins, lipids, and carbohydrates (glycans). Glycans play a unique role of joining three principal hierarchical levels of the living world: (1) the molecular level (pathogenic agents and vaccine recognition by the immune system, metabolic pathways involving saccharides that provide cells with energy, and energy accumulation via photosynthesis); (2) the nanoscale level (cell membrane mechanics, structural support of biomolecules, and the glycosylation of macromolecules); (3) the microscale and macroscale levels (polymeric materials, such as cellulose, starch, glycogen, and biomass). NMR spectroscopy is the most powerful research approach for getting insight into the solution structure and function of carbohydrates at all hierarchical levels, from monosaccharides to oligo- and polysaccharides. Recent progress in computational procedures has opened up novel opportunities to reveal the structural information available in the NMR spectra of saccharides and to advance our understanding of the corresponding biochemical processes. The ability to predict the molecular geometry and NMR parameters is crucial for the elucidation of carbohydrate structures. In the present paper, we review the major NMR spectrum simulation techniques with regard to chemical shifts, coupling constants, relaxation rates and nuclear Overhauser effect prediction applied to the three levels of glycomics. Outstanding development in the related fields of genomics and proteomics has clearly shown that it is the advancement of research tools (automated spectrum analysis, structure elucidation, synthesis, sequencing and amplification) that drives the large challenges in modern science. Combining NMR spectroscopy and the computational analysis of structural information encoded in the NMR spectra reveals a way to the automated elucidation of the structure of carbohydrates. This journal is © The Royal Society of Chemistry 2013.