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Emission of twin jets from a driven matter-wave soliton in a quasi-one-dimensional geometryMay 24 2019The modulation of the interaction between the atoms in a matter-wave soliton in a quasi-one-dimensional optical trap triggers an emission of correlated atom jets. We characterize the dependence of jet properties on the frequency, amplitude and length ... More

Cesium bright matter-wave solitons and soliton trainsFeb 08 2019Mar 05 2019A study of bright matter-wave solitons of a cesium Bose-Einstein condensate (BEC) is presented. Production of a single soliton is demonstrated and dependence of soliton atom number on the interatomic interaction is investigated. Formation of soliton trains ... More

On normal forms of complex points of small $\mathcal{C}^{2}$-perturbations of real $4$-manifolds embedded in a complex $3$-manifoldJan 07 2019The purpose of this paper is to give a better understanding of complex points up to quadratic terms of real codimension $2$ submanifolds embedded in a complex $3$-manifold. We answer the question how a normal form of a pair of one arbitrary and one symmetric ... More

On regular Stein neighborhoods of a union of two maximal totally real subspaces in $\mathbb{C}^n$Sep 16 2016May 10 2018We present a construction of regular Stein neighborhoods of a union of maximally totally real subspaces $M=(A+iI)\mathbb{R}^n$ and $N=\mathbb{R}^n$ in $\mathbb{C}^n$, provided that the entries of a real $n \times n$ matrix $A$ are sufficiently small. ... More

Lightning-triggered electroporation and electrofusion as possible contributors to natural HGT among prokaryotesDec 21 2012Phylogenetic studies show that horizontal gene transfer (HGT) is a significant contributor to genetic variability of prokaryotes, and was perhaps even more abundant during early evolution. Hitherto, research of natural HGT has mainly focused on three ... More

Defect of a Kronecker product of unitary matricesSep 21 2010Nov 19 2010The generalized defect D(U) of a unitary NxN matrix U with no zero entries is the dimension of the real space of directions, moving into which from U we do not disturb the moduli |U_ij| as well as the Gram matrix U'*U in the first order. Then the defect ... More

On regular Stein neighborhoods of a union of two totally real planes in $\mathbb{C}^2$Apr 03 2015Apr 22 2016In this paper we find regular Stein neighborhoods for a union of totally real planes $M=(A+iI)\mathbb{R}^2$ and $N=\mathbb{R}^2$ in $\mathbb{C}^2$ provided that the entries of a real $2 \times 2$ matrix $A$ are sufficiently small. A key step in our proof ... More

Defect and equivalence of unitary matrices. The Fourier caseOct 30 2013Jun 26 2014Consider the real space D_U of directions moving into which from a unitary N x N matrix U we do not disturb its unitarity and the moduli of its entries in the first order. dim( D_U ) is called the defect of U and denoted D(U). We give an account of Alexander ... More

On regular Stein neighborhoods of a union of two maximal totally real subspaces in $\mathbb{C}^n$Sep 16 2016We present a construction of regular Stein neighborhoods of a union of maximally totally real subspaces $M=(A+iI)\mathbb{R}^n$ and $N=\mathbb{R}^n$ in $\mathbb{C}^n$, provided that the entries of a real $n \times n$ matrix $A$ are sufficiently small. ... More

Permutation Equivalence Classes of Kronecker Products of Unitary Fourier MatricesJan 14 2005Kronecker products of unitary Fourier matrices play important role in solving multilevel circulant systems by a multidimensional Fast Fourier Transform. They are also special cases of complex Hadamard (Zeilinger) matrices arising in many problems of mathematics ... More

Thermally Activated Motion of Sodium Cations in Insulating Parent Low-Silica X ZeoliteJul 06 2017We report a $^{23}$Na spin-lattice relaxation rate, $T_1^{-1}$, in low-silica X zeolite. $T_1^{-1}$ follows multiple BPP-type behavior as a result of thermal motion of sodium cations in insulating material. The estimated lowest activation energy of 15~meV ... More

Defect of a unitary matrixFeb 17 2007Dec 20 2007We analyze properties of a map B = f(U) sending a unitary matrix U of size N into a doubly stochastic matrix defined by B_{i,j} = |U_{i,j}|^2. For any U we define its DEFECT, determined by the dimensionality of the space being the image Df(T_U Unitaries) ... More

Cesium bright matter-wave solitons and soliton trainsFeb 08 2019A setup for studying bright matter-wave solitons of a cesium Bose-Einstein condensate (BEC) is presented. Production of a single soliton is demonstrated and dependence of soliton atom number on the interatomic interaction is studied. Formation of soliton ... More

Hermite parametric surface interpolation based on Argyris elementMay 04 2018In this paper, Hermite interpolation by parametric spline surfaces on triangulations is considered. The splines interpolate points, the corresponding tangent planes and normal curvature forms at domain vertices and approximate tangent planes at midpoints ... More

A study on spline quasi-interpolation based quadrature rules for the isogeometric Galerkin BEMJul 30 2018Two recently introduced quadrature schemes for weakly singular integrals [Calabr\`o et al. J. Comput. Appl. Math. 2018] are investigated in the context of boundary integral equations arising in the isogeometric formulation of Galerkin Boundary Element ... More

A concise guide to complex Hadamard matricesDec 19 2005May 25 2006Complex Hadamard matrices, consisting of unimodular entries with arbitrary phases, play an important role in the theory of quantum information. We review basic properties of complex Hadamard matrices and present a catalogue of inequivalent cases known ... More

On positivity of principal minors of bivariate Bezier collocation matrixJun 03 2011Aug 14 2015It is well known that the bivariate polynomial interpolation problem at domain points of a triangle is correct. Thus the corresponding interpolation matrix $M$ is nonsingular. L.L. Schumaker stated the conjecture, that the determinant of $M$ is positive. ... More

On Normal Forms of Complex Points of codimension 2 submanifoldsSep 22 2017Feb 07 2018In this paper we present some linear algebra behind quadratic parts of quadratically flat complex points of codimension two real submanifold in a complex manifold. Assuming some extra nondegenericity and using the result of Hong, complete normal form ... More

GitHub open source project recommendation systemFeb 08 2016Hosting platforms for software projects can form collaborative social networks and a prime example of this is GitHub which is arguably the most popular platform of this kind. An open source project recommendation system could be a major feature for a ... More

Large electric-field induced strain in BiFeO3 ceramicsApr 13 2011Large bipolar strain of up to 0.36% (peak-to-peak value) was measured in BiFeO3 ceramics at low frequency (0.1 Hz) and large amplitude (140 kV/cm) of the driving field. This strain is comparable to that achievable in highly efficient Pb-based perovskite ... More

Recommender system for learning SQL using hintsJul 07 2018Today's software industry requires individuals who are proficient in as many programming languages as possible. Structured query language (SQL), as an adopted standard, is no exception, as it is the most widely used query language to retrieve and manipulate ... More

Fine Hand Segmentation using Convolutional Neural NetworksAug 26 2016We propose a method for extracting very accurate masks of hands in egocentric views. Our method is based on a novel Deep Learning architecture: In contrast with current Deep Learning methods, we do not use upscaling layers applied to a low-dimensional ... More

Role of charged defects on the electrical and electro-mechanical properties of rhombohedral Pb(Zr,Ti)O3 with oxygen octahedra tiltsJan 31 2016Oxygen octahedra tilting is a common structural phenomenon in perovskites and has been subject of intensive studies, particularly in rhombohedral Pb(Zr,Ti)O3 (PZT). Early reports suggest that the tilted octahedra may strongly affect the domain switching ... More

Adaptive isogeometric analysis with hierarchical box splinesMay 04 2018Isogeometric analysis is a recently developed framework based on finite element analysis, where the simple building blocks in geometry and solution space are replaced by more complex and geometrically-oriented compounds. Box splines are an established ... More

Convexity in scientific collaboration networksNov 27 2018Convexity in a network (graph) has been recently defined as a property of each of its subgraphs to include all shortest paths between the nodes of that subgraph. It can be measured on the scale [0, 1] with 1 being assigned to fully convex networks. The ... More

Piezoelectric nonlinearity and frequency dispersion of the direct piezoelectric response of BiFeO3 ceramicsAug 27 2012We report on the frequency and stress dependence of the direct piezoelectric d33 coefficient in BiFeO3 ceramics. The measurements reveal considerable piezoelectric nonlinearity, i.e., dependence of d33 on the amplitude of the dynamic stress. The nonlinear ... More

Birkhoff's polytope and unistochastic matrices, N=3 and N=4Feb 19 2004Feb 24 2004The set of bistochastic or doubly stochastic N by N matrices form a convex set called Birkhoff's polytope, that we describe in some detail. Our problem is to characterize the set of unistochastic matrices as a subset of Birkhoff's polytope. For N=3 we ... More

Mubs and Hadamards of Order SixOct 19 2006Jun 01 2007We report on a search for mutually unbiased bases (MUBs) in 6 dimensions. We find only triplets of MUBs, and thus do not come close to the theoretical upper bound 7. However, we point out that the natural habitat for sets of MUBs is the set of all complex ... More

An adaptive IGA-BEM with hierarchical B-splines based on quasi-interpolation quadrature schemesJul 10 2018Jul 12 2018The isogeometric formulation of Boundary Element Method (BEM) is investigated within the adaptivity framework. Suitable weighted quadrature rules to evaluate integrals appearing in the Galerkin BEM formulation of 2D Laplace model problems are introduced. ... More

GPU-based Parallel Computation Support for StanJul 01 2019This paper details an extensible OpenCL framework that allows Stan to utilize heterogeneous compute devices. It includes GPU-optimized routines for the Cholesky decomposition, its derivative, other matrix algebra primitives and some commonly used likelihoods, ... More