Novosibirsk State University
  • Novosibirsk, Russia
Recent publications
The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.
Terminal deoxynucleotidyltransferase (TdT) is a member of the DNA polymerase X family that is responsible for random addition of nucleotides to single-stranded DNA. We present investigation into the role of metal ions and specific interactions of dNTP with active-site amino acid residues in the mechanisms underlying the recognition of nucleoside triphosphates by human TdT under pre–steady-state conditions. In the elongation mode, the ratios of translocation and dissociation rate constants, as well as the catalytic rate constant were dependent on the nature of the nucleobase. Preferences of TdT in dNTP incorporation were researched by molecular dynamics simulations of complexes of TdT with a primer and dNTP or with the elongated primer. Purine nucleotides lost the “summarised” H-bonding network after the attachment of the nucleotide to the primer, whereas pyrimidine nucleotides increased the number and relative lifetime of H-bonds in the post-catalytic complex. The effect of divalent metal ions on the primer elongation revealed that Me ²⁺ cofactor can significantly change parameters of the primer elongation by strongly affecting the rate of nucleotide attachment and the polymerisation mode.
We report on transition from single longitudinal mode operation to regular mode-hopping dynamics in Erbium-doped ring fiber laser with a saturable absorber. The laser can be switched from wavelength stabilization (with stability time of up to tens of seconds) to a wavelength self-sweeping regime (in the range of about 20 pm near 1560 nm) with an increase of the pump power and with elongation of the absorbing fiber length. The observed effect is associated with an interplay of amplitude and phase dynamic gratings. Additionally, a continuous wave single-frequency self-sweeping operation in an Erbium-doped fiber laser is demonstrated for the first time. The results are useful both for single-frequency and self-sweeping laser development.
The integration between advanced techniques for groundwater vulnerability to contamination is necessary for groundwater management and risk assessment for aquifer systems. 3D geophysical/hydrogeological modeling has been developed for the delineation of lithostratigraphic layers of the Nubian Sandstone aquifer system based on geophysical and hydrogeological borehole data for 79 groundwater wells with a distance of 1 km between each well in the study area of El-Oweinat. Several parameters contributing to groundwater vulnerability have been selected and represented in 3D views as follows: surface elevation; water table; unsaturated and saturated thicknesses; laminar head losses; turbulent head losses; total drawdown; specific capacity; aquitard and aquifer thicknesses to monitor the aquifer vulnerability to contamination using Petrel software. This integration of lithostratigraphic layers and aquifer parameters (e.g. water depth) can significantly help to delineate and understand both the water pathway and attenuation processes caused by the aquitard layers, which serve as a protective layer for the underlying aquifer layers. 3D modeling of the aquifer system allows the decision-maker to visualize and deal with the issue of contamination as quickly as possible.
The paper examines the dependence of economic growth on the level of energy consumption in various countries of the world, divided into groups according to the level of economic development and geographical location (macro-regions). It is shown that the impact of energy consumption on gross domestic product (GDP) is stronger in non-OECD countries than in the Organization for Economic Co-operation and Development (OECD) countries, which is explained by the extensive nature of economic development. This relationship is clearly seen in such macro-regions as the Asia-Pacific region, Africa, Central and South America. The energy intensity of the countries of the world is calculated, and the main trends for different groups of countries are analyzed.
In 21st century with the growing awareness about climate change and role of fossil fuels in green-house effect, the world is looking for cleaner alternatives for energy sources including the active use of liquefied natural gas (LNG). LNG trade volumes have increased over 3 times in last 20 years and reached almost 50% of global natural gas trade. The purpose of this research is to analyze the possible application of the network link prediction algorithm for the LNG market. Such analysis will help to find out the most feasible potential trade routes between global LNG trade partners and at the same time provide a statistical decision support model to help LNG suppliers find potential LNG markets. Quantitative analysis of the existing network of world LNG trade proved low degree of centrality and density, therefore there is a large room for growth in LNG trade connections. At the same time, the network is divided into 6 large subgroups on a territorial basis. The results from the study showed that European importing countries are emerging as the top potential market for LNG, impacting the developing countries gas supply security as LNG cargoes are being diverted to Europe. The most likely suppliers in this case may be Qatar, Egypt and Norway.
We introduce the notion of λ-double Lie algebra, which coincides with usual double Lie algebra when λ=0. We show that every λ-double Lie algebra for λ≠0 provides the structure of modified double Poisson algebra on the free associative algebra. In particular, it confirms the conjecture of S. Arthamonov (2017). We prove that there are no simple finite-dimensional λ-double Lie algebras.
A detailed analysis of the bremsstrahlung spectrum at nonrelativistic electron scattering on argon and xenon is carried out. It is shown that the approximate formulas widely used for the description of bremsstrahlung spectra lead to predictions that significantly differ from the exact results. In the limit when the photon frequency tends to zero, a rigorous proof of the relationship between the spectrum of the bremsstrahlung with a transport cross section of electron scattering on an atom is given. This proof does not require any assumptions about the dependence of the scattering phases on energy. For electron energies lower than the luminescence threshold, it is shown that the predictions for a number of radiated photons obtained by the exact formula are in good agreement with the available experimental data.
Проведен сравнительный анализ точности численных схем WENO (Weighted Essentially Non-Oscillatory), CWA (Compact high order Weak Approximation) и CU (Central-Upwind) при расчете разрывных решений с ударными волнами, распространяющимися с переменной скоростью. Показано, что WENO и CU схемы повышенной точности на гладких решениях, при построении которых используется нелинейная коррекция потоков, имеют приблизительно пеpвый поpядок интегральной сходимости на интервалах, одна из границ которых находится в области влияния ударной волны. В то же время CWA схема повышенного порядка слабой аппроксимации, при построении которой нелинейная коррекция потоков не применяется, сохраняет приблизительно второй порядок интегральной сходимости в областях влияния ударных волн. В результате в этих областях точность WENO и CU схем оказывается существенно ниже, чем CWA схемы. Предлагается теоретическое обоснование этих численных результатов.
This work is aimed at the numerical analysis of the stationary non-isothermal flows of an incompressible viscoelastic polymer fluid in the channels with elliptical cross-sections. The description of such flows is done on the basis of the mesoscopic approach, and the resolving equations are derived. For solving them three algorithms, which use different techniques of constructing the approximate solutions, are designed: the least-squares collocation method based on the piecewise polynomial approximations, which lead to the overdetermined systems of linear algebraic equations; the finite element method, which uses weak formulations; and the non-local method without saturation, which operates with the global approximations in the elliptical coordinate system and with the matrix Sylvester equations. The proposed algorithms are verified by solving the test problem with the known analytical solution. Further we use them for the numerical analysis of the polymer fluid flows with its parameters varying in wide ranges. Comparison of the results obtained by the different algorithms shows their high performance and confirms that the solution of the considered non-linear problem exists and that it was computed accurately. The singularities of the obtained stationary solutions are analyzed. Taking them into account within the proposed algorithms enables us to increase the accuracy and the speed of simulations.
A combined kinetic Monte Carlo algorithm and continuous thermodynamically based model for simulation of heterogeneous nucleation of GaN islands on a substrate under burst regime when a long incubation time is followed by a rapid nucleation of stable nuclei is developed. In this model the kinetics of GaN islands nucleation on a substrate during their aggregation and disaggregation is simulated directly by the Monte Carlo method while the size of stable nuclei is taken from the thermodynamic theory of nucleation with varying supersaturation under metastable conditions. Simulations are carried out in conditions close to the experimental data on the GaN nanowires growth. Both the height and radius distributions of nanowires are extracted from the simulations which start from the very beginning of the incident Ga and N atoms on a substrate and finish with a stable distribution of nanowires whose radii ri stopped to grow and the heights become 2–4 times larger than their radii. In contrast to standard Becker–Döring nucleation theory, where the following general behavior is known: the longer the incubation time the slower the nucleation rate, a combined hybrid Monte Carlo and metastable thermodynamic model suggested is able to predict a long incubation time followed by relatively rapid nucleation regime. A series of numerical simulations presented supports this conclusion.
The conformational dynamics of the paramagnetic complex [Dy(H2O)n(DOTA)]⁻ has been studied by dynamic ¹H NMR within the framework of the signal bandshape analysis technique taking into account the temperature variation of the lanthanide-induced shifts (LIS). The corresponding values of the free energy of activation ΔG≠298 were 68 kJ/mol for the SAP → TSAP transformation process, and 60 kJ/mol for the reverse transition (TSAP → SAP). In the series of [Ln(H2O)n(DOTA)]⁻ complexes from praseodymium to lutetium, there is first a monotonic increase in the free energy of activation ΔG≠298 of the conformational transition up to Dy, then there is a gradual decrease in the activation barrier (as a manifestation of the gadolinium break effect).
Directed transformation of available natural compounds with native biological activity is a promising area of research in organic and medicinal chemistry aimed at finding effective drug substances. The number of scientific publications devoted to the transformation of natural compounds and investigations of their pharmacological properties, in particular, monoterpenes and their nearest derivatives, increases every year. At the same time, the chemistry of nitrogen-containing heterocyclic compounds has been actively developed since the 1950s after the news that the benzimidazole core is an integral part of the structure of vitamin B12. At the time of writing this review, the data on chemical modifications of monoterpenes and their nearest derivatives leading to formation of compounds with a nitrogen-containing heterocycle core have not been summarized and systematized in terms of chemical transformations. In this review, we tried to summarize the literature data on the preparation and properties of nitrogen-containing heterocyclic compounds synthesized from monoterpenes/monoterpenoids and their nearest derivatives for the period from 2000 to 2021.
In this paper we consider three problems of searching for disjoint subsets among a finite set of points in an Euclidean space. In all three problems, it is required to maximize the size of the minimal cluster so that each intra-cluster scatter of points relative to the cluster center does not exceed a predetermined threshold. In the first problem, the centers of the clusters are given as input. In the second problem, the centers are unknown, but belong to the initial set. In the last problem, the center of each cluster is defined as the arithmetic mean of all its elements. It is known that all three problems are NP-hard even in the one-dimensional case. The main result of the work is constant-factor approximation algorithms for all three problems. For the first two problems, 1/2-approximate algorithms for an arbitrary space dimension are constructed. Also we propose a 1/2-approximate algorithm for the one-dimensional case of the third problem. KeywordsEuclidean spaceClusteringMax-min problemNP-hardnessBounded scatterApproximation algorithm
Inflammatory bowel diseases (IBD) are chronic and relapsing inflammatory disorders of the gastrointestinal tract with complex etiology and no strategies for complete cure. IBD are often complicated by mental disorders like anxiety and depression, indicating substantial shifts in the microbiota gut-brain axis. However, the mechanisms connecting IBD to mental diseases are still under debate. Here we use Muc2 knockout mouse model of chronic colitis to uncouple the effects of the intestinal microbiota on host behavior from chronic inflammation in the gut. Muc2 knockout male mice exhibit high exploratory activity, reduced anxiety-related behaviors, impaired sensorimotor gating, and altered social preference towards males and females. Microbial transfer to wild-type mice via littermate co-housing shows that colitis-associated microbiota rather than inflammation per se defines behavioral features in Muc2 colitis model. Metagenomic profiling and combination of antibiotic treatments revealed that bacterial species Akkermansia muciniphila is associated with the behavioral phenotype in mutants, and that its intestinal abundance correlates with social preference towards males. Metabolomic analysis together with pharmacological inhibition of Gly and NMDA receptors helped us to determine that brain glycine is responsible for the behavioral phenotype in Muc2 mice. Blood and brain metabolic profiles suggest that microbiota-dependent changes in choline metabolism might be involved in regulation of central glycine neurotransmission. Taken together, our data demonstrates that colitis-associated microbiota controls anxiety, sensorimotor gating and social behavior via metabolic regulation of the brain glycinergic system, providing new venues to combat neurological complications of IBD.
A bstract The singly Cabibbo-suppressed decay $$ {D}_s^{+} $$ D s + → K ⁺ π ⁺ π − π ⁰ is observed by using a data set corresponding to an integrated luminosity of 6.32 fb − 1 recorded by the BESIII detector at the centre-of-mass energies between 4.178 and 4.226 GeV. The first amplitude analysis of $$ {D}_s^{+} $$ D s + → K ⁺ π ⁺ π − π ⁰ reveals the sub-structures in this decay and determines the fractions and relative phases of different intermediate processes. The dominant intermediate process is $$ {D}_s^{+} $$ D s + → K *0 ρ ⁺ , with a fit fraction of (40 . 5 ± 2 . 8 stat . ± 1 . 5 syst . )%. With the detection efficiency based on our amplitude analysis, the absolute branching fraction for $$ {D}_s^{+} $$ D s + → K ⁺ π ⁺ π − π ⁰ is measured to be (9 . 75 ± 0 . 54 stat . ± 0 . 17 syst . ) × 10 − 3 .
A facile p-toluenesulfonic acid-catalyzed one-pot synthesis of biologically interesting fluorinated 2-arylchroman-4-one derivatives from 2-(triisopropylsilyl)ethynylphenols and aromatic aldehydes is described. This synthetic method is metal-free, operationally simple, cheap and productive. It provides a rapid access to the title compounds as well as their 3-benzylidene and 8-cinnamoyl derivatives, that are of interest as objects for the evaluation of their pharmacological properties.
Calcium aluminates are attractive materials possessing unique physicochemical properties. In the present work, three aluminate systems of varied Ca/Al ratio (1/2, 6/7, and 3/2) were prepared via aerogel technique and characterized. The decomposition behavior of hydroxide aerogels was studied by differential thermal analysis. As found, the specific surface area (SSA) of the samples dried in an autoclave at 265 °C is increased from 265 ± 10 to 515 ± 30 m2/g when the Ca/Al ratio changes from 3/2 to 1/2. The calcination of these samples at 500 °C decreases the SSA values ~1.6–1.8 times whereas the tendency regarding the Ca/Al ratio remains the same. Reflections assigned to a mixture of various calcium aluminate phases appeared in the diffraction patterns of the samples only after the calcination at 900 °C. The application of the spin probe electron paramagnetic resonance technique allowed registering electron-donor, weak electron-acceptor, and radical sites on the surface of all the aerogel samples of calcium aluminates calcined at 500 °C and their concentrations depended on the Ca/Al ratio. Graphical abstract
Proportional electroluminescence (EL) in noble gases is a physical process routinely used in two-phase (liquid–gas) detectors for low-energy astroparticle-physics experiments. In this work, the time properties of visible-light EL in two-phase argon detectors have been systematically studied for the first time. In particular, two unusual slow components in the EL signal, with their contributions and time constants increasing with electric field, were observed. This puzzling property is not expected in any of the known mechanisms of photon and electron emission in two-phase media. Time constants of these components is about 4–5 $$\upmu $$ μ s and 50 $$\upmu $$ μ s. In addition, a specific threshold behavior of the slow components was revealed: they emerged at a threshold in reduced electric field of 4.8 ± 0.2 Td regardless of the gas phase density, which is about 1 Td above the onset of standard (excimer) EL. There is a conspicuous similarity between this threshold and reduced field threshold of EL in NIR occurring via higher atomic excited states Ar $$^{*}(3p^{5}4p)$$ ∗ ( 3 p 5 4 p ) . An unexpected temperature dependence of slow components was also observed: their contribution decreased with temperature, practically disappearing at room temperature. We show that the puzzling properties of slow components can be explained in the framework of hypothesis that these are produced in the charge signal itself due to trapping of drifting electrons on metastable negative argon ions.
The purpose of thе article is to study the safety indicators of the curd product, which includes cottage cheese prepared with a starter culture of direct application "Evitalia," consisting of bacteria of the genus Lactococcus (L. acidophilius), Streptococcus (Streptococcus thermophilius) and propionobacteria. Other ingredients are crushed mass from green buckwheat, candied pumpkin, cooked Jerusalem artichoke sirup, and fat emulsion based on coconut oil. The sweetness of the curd product is provided by Jerusalem artichoke sirup, whereas fat emulsion based on coconut oil enriches the product with unsaturated fatty acids and gives plasticity and uniformity of structure. The results of the study showed that the formulation with the following ingredients: 40% of cottage cheese, 40% of crushed mass from green buckwheat, 10% of candied pumpkin, 10% of coconut oil emulsion-has the best organoleptic, physico-chemical, structural and plastic properties. The ratio of milk protein of cottage cheese and vegetable protein of green buckwheat is 1:1. This allowed to obtain the chemical composition of the product: proteins-29%, fats-9%, carbohydrates-59%, ash-3%. The obtained research and technological solutions can be used at dairy industry enterprises in the production of combined dairy and vegetable products.
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2,326 members
Alexander Tsyplakov
  • Department of Economics
Michael Sergeev
  • Chair of General Biology and Ecology
Sergey Kobtsev
  • Division of Laser Physics and Innovative Technologies
Sergey Netesov
  • Department of Natural Sciences
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Rector - Prof. Mikhail Fedoruk
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