Results for "Andrii Sotnikov"

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Magnetic field dependence and the possibility of filtering ultraslow light pulses in atomic gases with Bose-Einstein condensatesOct 28 2010This paper studies theoretically the ultraslow light phenomenon in Bose-Einstein condensates of alkali-metal atoms. The description is based on the linear approach that is developed in the framework of the Green function formalism. It is pointed out that ... More
Magnetic phases of mass- and population-imbalanced ultracold fermionic mixtures in optical latticesJan 08 2013May 06 2013We study magnetic phases of two-component mixtures of ultracold fermions with repulsive interactions in optical lattices in the presence of both hopping and population imbalance by means of dynamical mean-field theory (DMFT). It is shown that these mixtures ... More
Perspectives of optical lattices with state-dependent tunneling in approaching quantum magnetism in the presence of the external harmonic trapping potentialSep 17 2015Feb 08 2016We study theoretically potential advantages of two-component mixtures in optical lattices with state-dependent tunneling for approaching long-range-order phases and detecting easy-axis antiferromagnetic correlations. While we do not find additional advantages ... More
Critical entropies and magnetic-phase-diagram analysis of ultracold three-component fermionic mixtures in optical latticesJun 25 2015Aug 25 2015We study theoretically many-body equilibrium magnetic phases and corresponding thermodynamic characteristics of ultracold three-component fermionic mixtures in optical lattices described by the SU(3)-symmetric single-band Hubbard model. Our analysis is ... More
Field-induced exciton condensation in LaCoO3Apr 07 2016Jul 27 2016Motivated by recent observation of magnetic field induced transition in LaCoO3 we study the effect of external field in systems close to instabilities towards spin-state ordering and exciton condensation. We show that, while in both cases the transition ... More
Orbital magnetism of ultracold fermionic gases in a lattice: dynamical mean-field approachFeb 25 2016May 29 2016We study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-like atoms in optical lattices that can be effectively described by the two-band spin-$1/2$ Hubbard model including the Hund's exchange coupling term. Our main ... More
Propagation of relativistic charged particles in ultracold atomic gases with Bose-Einstein condensatesNov 23 2010Jan 15 2011We study theoretically some effects produced by a propagation of the charged particles in dilute gases of alkali-metal atoms in the state with Bose-Einstein condensates. The energy change of the high-speed (relativistic) particle that corresponds to the ... More
Green-function method in the theory of ultraslow electromagnetic waves in an ideal gas with Bose-Einstein condensatesJan 16 2009We propose a microscopic approach describing the interaction of an ideal gas of hydrogenlike atoms with a weak electromagnetic field. This approach is based on the Green-function formalism and an approximate formulation of the method of second quantization ... More
Role of temperature effects in the phenomenon of ultraslow electromagnetic pulses in Bose-Einstein condensates of alkali-metal atomsNov 17 2009We study the temperature dependence of optical properties of dilute gases of alkali-metal atoms in the state with Bose-Einstein condensates. The description is constructed in the framework of the microscopic approach that is based on the Green-functions ... More
Magnetic ordering of three-component ultracold fermionic mixtures in optical latticesFeb 14 2014Jun 03 2014We study finite-temperature magnetic phases of three-component mixtures of ultracold fermions with repulsive interactions in optical lattices with simple cubic or square geometry by means of dynamical mean-field theory (DMFT). We focus on the case of ... More
Suppression and revival of long-range ferromagnetic order in the multiorbital Fermi-Hubbard modelFeb 08 2018Jun 29 2018By means of dynamical mean-field theory allowing for complete account of SU(2) rotational symmetry of interactions between spin-1/2 particles, we observe a strong effect of suppression of ferromagnetic order in the multiorbital Fermi-Hubbard model in ... More
Advantages of Mass-Imbalanced Ultracold Fermionic Mixtures for Approaching Quantum Magnetism in Optical LatticesMar 21 2012Aug 13 2012We study magnetic phases of two-component mixtures of ultracold fermions with repulsive interactions in optical lattices in the presence of hopping imbalance. Our analysis is based on dynamical mean-field theory (DMFT) and its real-space generalization ... More
Suppression and revival of long-range ferromagnetic order in the multiorbital Fermi-Hubbard modelFeb 08 2018By means of dynamical mean-field theory allowing for complete account of SU(2) rotational symmetry of interactions between spin-1/2 particles, we observe a strong effect of suppression of ferromagnetic order in the multiorbital Fermi-Hubbard model in ... More
Effects of anisotropy in simple lattice geometries on many-body properties of ultracold fermions in optical latticesMay 11 2015Nov 01 2015We study the effects of anisotropic hopping amplitudes on quantum phases of ultracold fermions in optical lattices described by the repulsive Fermi-Hubbard model. In particular, using dynamical mean-field theory (DMFT) we investigate the dimensional crossover ... More
Pressure-induced spin-state ordering in Sr$_2$CoO$_3$FFeb 18 2019May 14 2019We study theoretically low-temperature phases of a recently synthesized compound Sr$_2$CoO$_3$F under pressure. The analysis combining LDA+DMFT and a strong-coupling effective model points to the existence of not only normal paramagnetic and antiferromagnetic ... More
Pressure-induced spin-state ordering in Sr$_2$CoO$_3$FFeb 18 2019We study theoretically low-temperature phases of a recently-synthesized compound Sr$_2$CoO$_3$F under pressure. The analysis combining LDA+DMFT and strong-coupling effective model points to the existence of not only normal paramagnetic and antiferromagnetic ... More
Miniversal deformations of pairs of symmetric matrices under congruenceApr 13 2011May 29 2018For each pair of complex symmetric matrices $(A,B)$ we provide a normal form with a minimal number of independent parameters, to which all pairs of complex symmetric matrices $(\widetilde{A},\widetilde{B})$, close to $(A,B)$ can be reduced by congruence ... More
Opening up and control of spectral gaps of the Laplacian in periodic domainsAug 19 2013Dec 20 2014The main result of this work is as follows: for arbitrary pairwise disjoint finite intervals $(\alpha_j,\beta_j)\subset[0,\infty)$, $j=1,\dots,m$ and for arbitrary $n\geq 2$ we construct the family of periodic non-compact domains $\{\Omega^\varepsilon\subset\mathbb{R}^n\}_{\varepsilon>0}$ ... More
Convergence of point processes associated with coupon collector's and Dixie cup problemsApr 29 2019We prove that, in the coupon collector's problem, the point processes given by the times of r-th arrivals for coupons of each type, centered and normalized in a proper way, converge toward a non-homogeneous Poisson point process. This result is then used ... More
Continuous counterparts of Poisson and binomial distributions and their propertiesMar 24 2013On the basis of integral representations of Poisson and binomial distribution functions via complete and incomplete Euler \Gamma- and B-functions, we introduce and discuss continuous counterparts of the Poisson and binomial distributions. The former turns ... More
Honest confidence sets in nonparametric IV regression and other ill-posed modelsNov 09 2016This paper provides novel methods for inference in a very general class of ill-posed models in econometrics, encompassing the nonparametric instrumental regression, different functional regressions, and the deconvolution. I focus on uniform confidence ... More
Using Elements Of Semantic Parsing In E-Learning EnvironmentsJul 01 2018Possibilities for using semantic parsing to estimate the correspondence of text materials to teaching aims, correspondence of test task to theoretical materials and other problems arising during the distance course designing and educational process itself ... More
Designing a blended learning of system programming for software engineering bachelorsJul 30 2018The research objective is to design a blended learning of system programming for software engineering bachelors. Under blended learning we understand the way of implementing the content of the training, which integrates classroom and non-auditing learning ... More
Homogenization of spectral problem on Riemannian manifold consisting of two domains connected by many tubesNov 17 2010Dec 18 2010The paper deals with the asymptotic behavior as $\eps\to 0$ of the spectrum of Laplace-Beltrami operator $\Delta\e$ on the Riemannian manifold $M\e$ ($\mathrm{\dim} M\e=N\geq 2$) depending on a small parameter $\eps>0$. $M\e$ consists of two perforated ... More
Studies of correlations between measurements of jet observablesSep 22 2016We present a method for calculation of statistical correlations between measured jet observables in high energy collisions. The method is compared to sampling based methods used in the past. The case of measurements of jet rates in $e^+e^-$ collisions ... More
UHECRs deflections in the IRAS PSCz catalogue based models of extragalactic magnetic fieldNov 22 2006We present an investigation of the propagation of Ultra High Energy Cosmic Rays (UHECRs) in extragalactic magnetic field (EGMF). We use the IRAS PSCz catalogue in order to reconstruct EGMF taking into account power-law dependence between the magnetic ... More
Optimal conditions for high-fidelity dispersive readout of a qubit with a photon-number-resolving detectorDec 29 2015Feb 27 2016We determine the optimal parameters for a simple and efficient scheme of dispersive readout of a qubit. Depending on the qubit state (ground or excited), the resonance of a cavity is shifted either to the red or to the blue side. Qubit state is inferred ... More
Miniversal deformations of pairs of skew-symmetric matrices under congruenceApr 13 2011Jun 10 2016Miniversal deformations for pairs of skew-symmetric matrices under congruence are constructed. To be precise, for each such a pair $(A,B)$ we provide a normal form with a minimal number of independent parameters to which all pairs of skew-symmetric matrices ... More
Periodic elliptic operators with asymptotically preassigned spectrumJan 18 2012Feb 03 2012We deal with operators in $\mathbb{R}^n$ of the form $$\mathbf{A}=-{1\over \mathbf{b}(x)}\sum\limits_{k=1}^n\ds{\partial\over\partial x_k}(\mathbf{a}(x){\partial \over\partial x_k})$$ where $\mathbf{a}(x),\mathbf{b}(x)$ are positive, bounded and periodic ... More
Periodic Riemannian manifold with preassigned gaps in spectrum of Laplace-Beltrami operatorMay 12 2011Oct 31 2011It is known (E.L. Green (1997), O. Post (2003)) that for an arbitrary $m\in\mathbb{N}$ one can construct a periodic non-compact Riemannian manifold $M$ with at least $m$ gaps in the spectrum of the corresponding Laplace-Beltrami operator $-\Delta_M$. ... More
Multi-interval Sturm-Liouville boundary-value problems with distributional potentialsAug 24 2015We study the multi-interval boundary-value Sturm-Liouville problems with distributional potentials. For the corresponding symmetric operators boundary triplets are found and the constructive descriptions of all self-adjoint, maximal dissipative and maximal ... More
Lower-Hybrid Drift Instability and Macroscopic Flow of Colliding Magnetized PlasmasMay 04 2018Nov 10 2018Microscopic instability and macroscopic flow pattern resulting from colliding plasmas are studied analytically in support of laboratory experiments. The plasma flows are assumed to stream radially from two separate centers. In a quasi-planar (2D) geometry, ... More
Note on Ramsey theorem for posets with linear extensionsAug 18 2016In this note we consider a Ramsey type result for partially ordered sets. In particular, we give an alternative short proof of a theorem for a posets with multiple linear extensions recently obtained by Solecki and Zhao.
Relaxation of Blazar Induced Pair Beams in Cosmic VoidsAug 08 2012May 28 2013The stability properties of a low density ultra relativistic pair beam produced in the intergalactic medium by multi-TeV gamma-ray photons from blazars are analyzed. The problem is relevant for probes of magnetic field in cosmic voids through gamma-ray ... More
Evidence for strong extragalactic magnetic fields from Fermi observations of TeV blazarsJun 17 2010Magnetic fields in galaxies are produced via the amplification of seed magnetic fields of unknown nature. The seed fields, which might exist in their initial form in the intergalactic medium, were never detected. We report a lower bound $B\ge 3\times ... More
Example of periodic Neumann waveguide with gap in spectrumMay 25 2016In this note we investigate spectral properties of a periodic waveguide $\Omega^\varepsilon$ ($\varepsilon$ is a small parameter) obtained from a straight strip by attaching an array of $\varepsilon$-periodically distributed identical protuberances having ... More
Construction of Lyapunov functions for interconnected parabolic systems: an iISS approachOct 12 2014This paper is devoted to two issues. One is to provide Lyapunov-based tools to establish integral input-to-state stability (iISS) and input-to-state stability (ISS) for some classes of nonlinear parabolic equations. The other is to provide a stability ... More
Spectral estimates for Dirichlet Laplacian on tubes with exploding twisting velocityApr 19 2018We study the spectrum of the Dirichlet Laplacian on an unbounded twisted tube with twisting velocity exploding to infinity. If the tube cross section does not intersect the axis of rotation, then its spectrum is purely discrete under some additional conditions ... More
Elementary edge and screw dislocations visualized at the lattice periodicity level in smectic phase of colloidal rodsAug 02 2018We report on the identification and quantitative characterization of elementary edge and screw dislocations in a colloidal smectic phase of tip-labeled rods. Thanks to the micrometer layer spacing, direct visualization of dislocations has been performed ... More
Existence of non-coercive Lyapunov functions is equivalent to integral uniform global asymptotic stabilityJun 07 2018Jun 15 2018In this paper, a class of abstract dynamical systems is considered which encompasses a wide range of nonlinear finite- and infinite-dimensional systems. We show that the existence of a non-coercive Lyapunov function without any further requirements on ... More
Spectral estimates for Dirichlet Laplacian on tubes with exploding twisting velocityApr 19 2018Apr 01 2019We study the spectrum of the Dirichlet Laplacian on an unbounded twisted tube with twisting velocity exploding to infinity. If the tube cross section does not intersect the axis of rotation, then its spectrum is purely discrete under some additional conditions ... More
Diffraction dissociation at the LHCOct 22 2013Predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single- and double low missing-mass diffraction dissociation in the kinematical range of present and future LHC measurements are summarized.
Theory for entanglement of electrons dressed with circularly polarized light in Graphene and three-dimensional topological insulatorsMay 30 2013We have formulated a theory for investigating the conditions which are required to achieve entangled states of electrons on graphene and three-dimensional (3D) topological insulators (TIs). We consider the quantum entanglement of spins by calculating ... More
An upper bound for the size of a $k$-uniform intersecting family with covering number $k$Apr 16 2016Let $r(k)$ denote the maximum number of edges in a $k$-uniform intersecting family with covering number $k$. Erd\H{o}s and Lov\'asz proved that $ \lfloor k! (e-1) \rfloor \leq r(k) \leq k^k.$ Frankl, Ota, and Tokushige improved the lower bound to $r(k) ... More
Neutrinos from Extra-Large Hadron Collider in the Milky WayDec 04 2014Jun 24 2015Neutrino telescope IceCube has recently discovered astrophysical neutrinos with energies in the TeV-PeV range. We use the data of Fermi gamma-ray telescope to demonstrate that the neutrino signal has significant contribution from the Milky Way galaxy. ... More
Microlensing constraint on the size of the gamma-ray emission region in blazar B0218+357Jul 04 2015Context. Observations of the effect of microlensing in gravitationally lensed quasars could potentially be used to study the structure of the source on distance scales down to the size of the supermassive black hole powering the quasar activity. Aims. ... More
Characterizations of input-to-state stability for infinite-dimensional systemsJan 31 2017Sep 20 2017We prove characterizations of input-to-state stability (ISS) for a large class of infinite-dimensional control systems, including some classes of evolution equations over Banach spaces, time-delay systems, ordinary differential equations (ODE), switched ... More
Lyapunov characterization of input-to-state stability for semilinear control systems over Banach spacesAug 26 2017We prove that input-to-state stability (ISS) of nonlinear systems over Banach spaces is equivalent to existence of a coercive Lipschitz continuous ISS Lyapunov function for this system. For linear infinite-dimensional systems, we show that ISS is equivalent ... More
Characterizations of integral input-to-state stability for bilinear systems in infinite dimensionsJun 10 2014Mar 12 2016For bilinear infinite-dimensional dynamical systems, we show the equivalence between uniform global asymptotic stability and integral input-to-state stability. We provide two proofs of this fact. One applies to general systems over Banach spaces. The ... More
Gaps in the spectrum of a periodic quantum graph with periodically distributed $δ'$-type interactionsFeb 16 2015We consider a family of quantum graphs $\{(\Gamma,\mathcal{A}_\varepsilon)\}_{\varepsilon>0}$, where $\Gamma$ is a $\mathbb{Z}^n$-periodic metric graph and the periodic Hamiltonian $\mathcal{A}_\varepsilon$ is defined by the operation $-\varepsilon^{-1} ... More
Dwell-time conditions for robust stability of impulsive systemsFeb 15 2012Dec 21 2012We prove that impulsive systems, which possess an ISS Lyapunov function, are ISS for impulse time sequences, which satisfy the fixed dwell-time condition. If the ISS Lyapunov function is the exponential one, we provide stronger result, which guarantees ... More
Multidimensional Thermoelasticity for Nonsimple Materials -- Well-Posedness and Long-Time BehaviorMay 06 2016An initial-boundary value problem for the multidimensional type III thermoelaticity for a nonsimple material with a center of symmetry is considered. In the linear case, the well-posedness with and without Kelvin-Voigt and/or frictional damping in the ... More
Variability of gamma-ray emission from blazars on the black hole timescalesApr 03 2013We investigate the variability properties of blazars in the GeV band using the data of the Fermi/LAT telescope. We find that blazars exhibit variability on the scales down to the minimal timescale resolvable by Fermi, which is a function of the peak photon ... More
Mechanical Engineers Training in Using Cloud and Mobile Services in Professional ActivityJul 01 2018The purpose of this article is to identify mobile and cloud services of mechanical engineers professional activity and the principles of their use in higher technical education. There have been defined the criteria for evaluation of the tools for edu-cational ... More
Spectrum of a singularly perturbed periodic thin waveguideAug 01 2016We consider a family $\{\Omega^\varepsilon\}_{\varepsilon>0}$ of periodic domains in $\mathbb{R}^2$ with waveguide geometry and analyse spectral properties of the Neumann Laplacian $-\Delta_{\Omega^\varepsilon}$ on $\Omega^\varepsilon$. The waveguide ... More
Spectral properties of elliptic operator with double-contrast coefficients near a hyperplaneApr 09 2014Oct 20 2015In this paper we study the asymptotic behaviour as $\varepsilon\to 0$ of the spectrum of the elliptic operator $\mathcal{A}^\varepsilon=-{1\over b^\varepsilon}\mathrm{div}(a^\varepsilon\nabla)$ posed in a bounded domain $\Omega\subset\mathbb{R}^n$ $(n ... More
Gap control by singular Schrödinger operators in a periodically structured metamaterialFeb 21 2018Nov 20 2018We consider a family $\{\mathcal{H}^\varepsilon\}_{\varepsilon>0}$ of $\varepsilon\mathbb{Z}^n$-periodic Schr\"odinger operators with $\delta'$-interactions supported on a lattice of closed compact surfaces; within a minimal period cell one has $m\in\mathbb{N}$ ... More
Operator estimates for the crushed ice problemOct 09 2017Dec 26 2017Let $\Delta_{\Omega_\varepsilon}$ be the Dirichlet Laplacian in the domain $\Omega_\varepsilon:=\Omega\setminus\left(\cup_i D_{i \varepsilon}\right)$. Here $\Omega\subset\mathbb{R}^n$ and $\{D_{i \varepsilon}\}_{i}$ is a family of tiny identical holes ... More
Fast variability of gamma-ray emission from supermassive black hole binary OJ 287Nov 17 2010Nov 18 2010We report the discovery of fast variability of gamma-ray flares from blazar OJ 287. This blazar is known to be powered by binary system of supermassive black holes. The observed variability time scale T_var < 3-10 hr is much shorter than the light crossing ... More
High energy gamma rays from the massive black hole in the Galactic CenterAug 17 2004Accreting black holes are believed to be sites of possible particle acceleration with favorable conditions also for effective gamma-ray production. However, because of photon-photon pair production, only low energy (MeV) gamma-rays can escape these compact ... More
The shadow of dark matter as a shadow of string theorySep 04 2018Sep 17 2018We point out that the Kalb-Ramond field of string theory can generate a U_Y(1) portal to dark matter. This opens up a new approach to string phenomenology and entails the possibility that the U_Y(1) gauge field is related to a fundamental vector field ... More
Exploring the bounds on the positive semidefinite rankApr 21 2017The nonnegative and positive semidefinite (PSD-) ranks are closely connected to the nonnegative and positive semidefinite extension complexities of a polytope, which are the minimal dimensions of linear and SDP programs which represent this polytope. ... More
Eliminating Exposure Bias and Loss-Evaluation Mismatch in Multiple Object TrackingNov 27 2018Identity Switching remains one of the main difficulties Multiple Object Tracking (MOT) algorithms have to deal with. Many state-of-the-art approaches now use sequence models to solve this problem but their training can be affected by biases that decrease ... More
$δ'$-interaction as a limit of a thin Neumann waveguide with transversal windowAug 16 2018We consider a waveguide-like domain consisting of two thin straight tubular domains connected through a tiny window. The perpendicular size of this waveguide is of order $\varepsilon$. Under the assumption that the window is appropriately scaled we prove ... More
A nitrogen-vacancy spin based molecular structure microscope using multiplexed projection reconstructionMay 12 2015Methods and techniques to measure and image beyond the state-of-the-art have always been influential in propelling basic science and technology. Because current technologies are venturing into nanoscopic and molecular-scale fabrication, atomic-scale measurement ... More
Input-to-state stability of infinite-dimensional control systemsFeb 15 2012Sep 01 2012We develop tools for investigation of input-to-state stability (ISS) of infinite-dimensional control systems. We show that for certain classes of admissible inputs the existence of an ISS-Lyapunov function implies the input-to-state stability of a system. ... More
Binary Stochastic Filtering: a Solution for Supervised Feature Selection and Neural Network Shape OptimizationFeb 12 2019Binary Stochastic Filtering (BSF), the algorithm for feature selection and neuron pruning is proposed in this work. Filtering layer stochastically passes or filters out features based on individual weights, which are tuned during neural network training ... More
Research of X-ray induced conductivity of ZnSe sensors for their application in isotopic thickness gaugesJun 11 2011Measurements of intrinsic conductivity and X-ray induced conductivity were performed on specially undopped ZnSe samples. The measurements demonstrated that sensors made of ZnSe have minor intrinsic conductivity when heating up to the temperature of 180 ... More
Limit theorems for multidimensional renewal setsAug 12 2017Sep 03 2017Consider multiple sums $S_n$ on the $d$-dimensional integer grid,which are generated by i.i.d.\ random variables with a positive expectation. We prove the strong law of large numbers, the law of the iterated logarithm and the distributional limit theorem ... More
Neumann spectral problem in a domain with very corrugated boundarySep 16 2014Jan 06 2015Let $\Omega\subset\mathbb{R}^n$ be a bounded domain. We perturb it to a domain $\Omega^\varepsilon$ attaching a family of small protuberances with "room-and-passage"-like geometry ($\varepsilon>0$ is a small parameter). Peculiar spectral properties of ... More
On the spectrum of narrow Neumann waveguide with periodically distributed $δ'$ trapsMay 06 2014We analyze a family of singular Schr\"odinger operators describing a Neumann waveguide with a periodic array of singular traps of a $\delta'$ type. We show that in the limit when perpendicular size of the guide tends to zero and the $\delta'$ interactions ... More
Gaps in the spectrum of the Neumann Laplacian generated by a system of periodically distributed trapJan 14 2013The article deals with a convergence of the spectrum of the Neumann Laplacian in a periodic unbounded domain $\Omega^\varepsilon$ depending on a small parameter $\varepsilon>0$. The domain has the form $\Omega^\varepsilon=\mathbb{R}^n\setminus S^\varepsilon$, ... More
Global Well-Posedness and Exponential Stability for Heterogeneous Anisotropic Maxwell's Equations under a Nonlinear Boundary Feedback with DelayJun 30 2018Oct 06 2018We consider an initial-boundary value problem for the Maxwell's system in a bounded domain with a linear inhomogeneous anisotropic instantaneous material law subject to a nonlinear Silver-Muller-type boundary feedback mechanism incorporating both an instantaneous ... More
Partial redistribution in 3D non-LTE radiative transfer in solar atmosphere modelsJun 16 2016Resonance spectral lines such as H I Ly {\alpha}, Mg II h&k, and Ca II H&K that form in the solar chromosphere are influenced by the effects of 3D radiative transfer as well as partial redistribution (PRD). So far no one has modeled these lines including ... More
Non-coercive Lyapunov functions for infinite-dimensional systemsDec 20 2016Feb 20 2017We show that the existence of a non-coercive Lyapunov function is sufficient for uniform global asymptotic stability (UGAS) of infinite-dimensional systems with external disturbances provided the speed of decay is measured in terms of the norm of the ... More
Generic matrix polynomials with fixed rank and fixed degreeDec 13 2016The set ${\cal P}^{m\times n}_{r,d}$ of $m \times n$ complex matrix polynomials of grade $d$ and (normal) rank at most $r$ in a complex $(d+1)mn$ dimensional space is studied. For $r = 1, \dots , \min \{m, n\}-1$, we show that ${\cal P}^{m\times n}_{r,d}$ ... More
Generic skew-symmetric matrix polynomials with fixed rank and fixed odd gradeMar 16 2017We show that the set of $m \times m$ complex skew-symmetric matrix polynomials of odd grade $d$, i.e., of degree at most $d$, and (normal) rank at most $2r$ is the closure of the single set of matrix polynomials with the certain, explicitly described, ... More
Theoretical investigation of excitonic magnetism in LaSrCoO$_{4}$Dec 11 2017Mar 15 2018We use the LDA+U approach to search for possible ordered ground states of LaSrCoO$_4$. We find a staggered arrangement of magnetic multipoles to be stable over a broad range of Co $3d$ interaction parameters. This ordered state can be described as a spin-denity-wave-type ... More
A high-temperature expansion method for calculating paramagnetic exchange interactionsJan 13 2016The method for calculating the isotropic exchange interactions in the paramagnetic phase is proposed. It is based on the mapping of the high-temperature expansion of the spin-spin correlation function calculated for the Heisenberg model onto Hubbard Hamiltonian ... More
Quantum interference and contact effects in dangling bond loops on H-Si(100) surfacesJun 23 2015We perform electronic structure and quantum transport studies of dangling bond loops created on H-passivated Si(100) surfaces and connected to carbon nanoribbon leads. We model loops with straight and zigzag topologies as well as with varying lenght with ... More
Role Played by Surface Plasmons on Plasma Instability in Composite Layered StructuresOct 10 2014We demonstrate the engineering of a source of radiation from growing surface plasmons (charge density oscillations) in a composite nano-system. The considered hybrid nano-structure consists of a thick layer of a conducting substrate on whose surface a ... More
Scanning Gate Microscopy of Kondo Dots: Fabry-Pérot Interferences and Thermally Induced RingsMay 01 2013We study the conductance of an electron interferometer formed in a two dimensional electron gas between a nanostructured quantum contact and the charged tip of a scanning gate microscope. Measuring the conductance as a function of the tip position, thermally ... More
Decaying dark matter search with NuSTAR deep sky observationsJul 25 2016We present the results of the search for decaying dark matter with particle mass in the 6-40 keV range with NuSTAR deep observations of COSMOS and ECDFS empty sky fields. We show that main contribution to the decaying dark matter signal from the Milky ... More
Lyapunov small-gain theorems for networks of not necessarily ISS hybrid systemsOct 05 2016We prove a novel Lyapunov-based small-gain theorem for networks of $ n \geq 2 $ hybrid systems which are not necessarily input-to-state stable. This result unifies and extends several small-gain theorems for hybrid and impulsive systems proposed in the ... More
The system of cloud oriented learning tools as an element of educational and scientific environment of high schoolJul 29 2018The aim of this research is to design and implementation of cloud based learning environment for separate division of the university. The analysis of existing approaches to the construction of cloud based learning environments, the formation of requirements ... More
Universal, high-fidelity quantum gates based on superadiabatic, geometric phases on a solid-state spin-qubit at room temperatureApr 29 2018Geometric phases and holonomies (their non-commuting generalizations) are a promising resource for the realization of high-fidelity quantum operations in noisy devices, due to their intrinsic fault-tolerance against noise and experimental imperfections. ... More
Direct and inverse approximation theorems of $2π$-periodic functions by Taylor--Abel--Poisson meansSep 30 2016We obtain direct and inverse approximation theorems of $2\pi$-periodic functions by Taylor--Abel--Poisson operators in the integral metric.
Modeling of the Vela complex including the Vela supernova remnant, the binary system gamma2 Velorum, and the Gum nebulaNov 04 2010We study the geometry and dynamics of the Vela complex including the Vela supernova remnant (SNR), the binary system gamma2 Velorum and the Gum nebula. We show that the Vela SNR belongs to a subclass of non-Sedov adiabatic remnants in a cloudy interstellar ... More
Electrically Reconfigurable Optical Metamaterial Based on Colloidal Dispersion of Metal Nano-Rods in Dielectric FluidDec 06 2009Dec 29 2009Optical metamaterials capture the imagination with breathtaking promises of nanoscale resolution in imaging and invisibility cloaking. We demonstrate an approach to construct a metamaterial in which metallic nanorods, of dimension much smaller than the ... More
The ZEUS long term data preservation projectJul 07 2016The ZEUS data preservation (ZEUS DP) project assures continued access to the data and documentation related to the experiment. It aims to provide the ability to continue the generation of valuable scientific results from these data in the future. This ... More
Blended learning modelsAug 07 2018The article presents the authors' organizational model of blended learning on the basis of existing models of learning at higher educational establishments. The model provides for using the learning management system and reflects current developments ... More
Optical and Boltzmann conductivities for extrinsic buckled honeycomb lattices at finite temperatureNov 22 2017The optical and Boltzmann conductivities have been calculated for doped buckled honeycomb lattice structures such as silicene and germanene, as functions of temperature. By making use of previous results for the temperature-dependent chemical potential ... More
Engineering semiconductor hybrids for sensingOct 14 2014The effect of screening of the coulomb interaction between two layers of two-dimensional electrons, such as in graphene, by a highly doped semiconducting substrate is investigated. We employ the random-phase approximation to calculate the dispersion equation ... More
Automatic Brain Structures Segmentation Using Deep Residual Dilated U-NetNov 10 2018Brain image segmentation is used for visualizing and quantifying anatomical structures of the brain. We present an automated ap-proach using 2D deep residual dilated networks which captures rich context information of different tissues for the segmentation ... More
Supervised learning magnetic skyrmion phasesMar 18 2018Oct 18 2018We propose and apply simple machine learning approaches for recognition and classification of complex non-collinear magnetic structures in two-dimensional materials. The first approach is based on the implementation of the single-hidden-layer neural network ... More
Combined analysis of charm-quark fragmentation-fraction measurementsSep 03 2015Jul 21 2016A summary of measurements of the fragmentation of charm quarks into a specific hadron is given. Measurements performed in photoproduction and deep inelastic scattering in $e^{\pm}p$, $pp$ and $e^+e^-$ collisions are compared, using up-to-date branching ... More
Direct and inverse approximation theorems of functions in the Orlicz type spaces S_MJan 22 2019In the Orlicz type spaces ${\mathcal S}_{M}$, we prove direct and inverse approximation theorems in terms of the best approximations of functions and moduli of smoothness of fractional order. We also show the equivalence between moduli of smoothness and ... More
Theory of nonlinear microwave absorption by interacting two-level systemsFeb 18 2018Jun 26 2018The microwave absorption and noise caused by quantum two-level systems (TLS) dramatically suppress the coherence in Josephson junction qubits that are promising candidates for a quantum information applications. Microwave absorption by TLSs is not clearly ... More
Triangle-free graphs with the maximum number of cyclesJan 06 2015Mar 21 2015It is shown that for $n\geq 141$, among all triangle-free graphs on $n$ vertices, the complete equibipartite graph is the unique triangle-free graph with the greatest number of cycles.
Increasing paths in countable graphsMay 09 2019In this paper we study variations of an old result by M\"{u}ller, Reiterman, and the last author stating that a countable graph has a subgraph with infinite degrees if and only if in any labeling of the vertices (or edges) of this graph by positive integers ... More