Results for "Albert Glensk"

total 1839took 0.18s
Anomalous phonon lifetime shortening in paramagnetic CrN caused by magneto-lattice coupling: A combined spin and ab initio molecular dynamics studyFeb 08 2018We study the mutual coupling of spin fluctuations and lattice vibrations in paramagnetic CrN by combining atomistic spin dynamics and ab initio molecular dynamics. The two degrees of freedom are dynamically coupled leading to non-adiabatic effects. Those ... More
Effects of aluminum on hydrogen solubility and diffusion in deformed Fe-Mn alloysApr 30 2016Jul 05 2016We discuss hydrogen diffusion and solubility in aluminum alloyed Fe-Mn alloys. The systems of interest are subjected to tetragonal and isotropic deformations. Based on ab initio modelling, we calculate solution energies, then employ Oriani's theory which ... More
Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objectsJun 29 2007Dec 21 2007All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources with the MAGIC ... More
Conserved network motifs allow protein-protein interaction predictionJun 22 2004High-throughput protein interaction detection methods are strongly affected by false positive and false negative results. Focused experiments are needed to complement the large-scale methods by validating previously detected interactions but it is often ... More
Local structures and local exchange interactions in doped magnetic materials of different dimensionalityOct 02 2015Defects intentionally introduced into magnetic materials often have a profound effect on the physical properties. Specifically tailored neutron spectroscopic experiments can provide detailed information on both the local exchange interactions and the ... More
Compressive Sensing Theory for Optical Systems Described by a Continuous ModelJul 03 2015Aug 01 2016A brief survey of the author and collaborators' work in compressive sensing applications to continuous imaging models.
Exact Localization and Superresolution with Noisy Data and Random IlluminationAug 18 2010Feb 26 2011This paper studies the problem of exact localization of sparse (point or extended) objects with noisy data. The crux of the proposed approach consists of random illumination. Several recovery methods are analyzed: the Lasso, BPDN and the One-Step Thresholding ... More
Time Reversal Communication in Rayleigh-Fading Broadcast Channels with PinholesDec 05 2005Sep 01 2006The paper presents an analysis of the time reversal in independent-multipath Rayleigh-fading channels with $N$ inputs (transmitters) and $M$ outputs (receivers). The main issues addressed are the condition of statistical stability, the rate of information ... More
Phase Space Models for Stochastic Nonlinear Parabolic Waves: Wave Spread and SingularityMar 09 2005Mar 19 2005We derive several kinetic equations to model the large scale, low Fresnel number behavior of the nonlinear Schrodinger (NLS) equation with a rapidly fluctuating random potential. There are three types of kinetic equations the longitudinal, the transverse ... More
Radiative Transfer Limits of Two-Frequency Wigner Distribution for Random Parabolic WavesSep 22 2006Oct 05 2006The present note establishes the self-averaging, radiative transfer limit for the two-frequency Wigner distribution for classical waves in random media. Depending on the ratio of the wavelength to the correlation length the limiting equation is either ... More
Un théorème limite pour les covariances des spins dans le modèle de Sherrington--Kirkpatrick avec champ externeMar 27 2007On \'{e}tudie la covariance (pour la mesure de Gibbs) des spins en deux sites dans le cas d'un mod\`{e}le de Sherrington--Kirkpatrick avec champ externe; lorsque le nombre de sites du mod\`{e}le tend vers l'infini, une \'{e}valuation asymptotique des ... More
From Vector Meson Dominance to Quark-Hadron DualityMar 15 2012A short review of the many contributions to hadron physics made by Mario Greco is presented. The review roughly covers his production between 1971 and 1974, just before the advent of QCD, when quark-model ideas, duality principles and vector meson dominance ... More
Probing Superluminal Neutrinos Via RefractionOct 10 2011Oct 12 2011One phenomenological explanation of superluminal propagation of neutrinos, which may have been observed by OPERA and MINOS, is that neutrinos travel faster inside of matter than in vacuum. If so neutrinos exhibit refraction inside matter and should exhibit ... More
Extensions to the Kompaneets Equation and Sunyaev-Zel'dovich DistortionSep 08 1997Analytical expressions are presented for relativistic corrections to the Kompaneets equation and the Sunyaev-Zel'dovich y-distortion. The latter provides a convenient method of inferring both the temperature and Thomson optical depth of the gas in clusters ... More
A MapReduce Approach to NoSQL RDF DatabasesJan 08 2016In recent years, the increased need to house and process large volumes of data has prompted the need for distributed storage and querying systems. The growth of machine-readable RDF triples has prompted both industry and academia to develop new database ... More
Comment on "Convection in a horizontal fluid layer under an inclined temperature gradient" [Phys. Fluids 23, 084107 (2011)]Jun 06 2012Ortiz-P\'erez and D\'avalos investigated the stability of parallel convective flow. From the article it seems that this equations of flow obtained by the authors. Meanwhile, it is well studied theoretically and experimentally(exact solution obtained more ... More
Long-term photometry of the eclipsing dwarf nova V893 Scorpii: Orbital period, oscillations, and a possible giant planetApr 10 2014The cataclysmic variable V893 Sco is an eclipsing dwarf nova which, apart from outbursts with comparatively low amplitudes, exhibits a particularly strong variability during quiescence on timescales of days to seconds.The present study aims to update ... More
Noncommutative supergeometry and dualityDec 22 1999Apr 27 2000We introduce a notion of Q-algebra that can be considered as a generalization of the notion of Q-manifold (a supermanifold equipped with an odd vector field obeying {Q,Q} =0). We develop the theory of connections on modules over Q-algebras and prove a ... More
Semiclassical approximation in Batalin-Vilkovisky formalismOct 21 1992Oct 23 1992The geometry of supermanifolds provided with $Q$-structure (i.e. with odd vector field $Q$ satisfying $\{ Q,Q\} =0$), $P$-structure (odd symplectic structure ) and $S$-structure (volume element) or with various combinations of these structures is studied. ... More
Late stages of stellar evolution with the Square Kilometer ArraySep 10 2004Stars at the end of their lives return much of their mass back to the ISM. This process is the main source of dust in the ISM, and potentially a source of large molecules. I discuss several areas where SKA will have major impact on our understanding of ... More
Photometry of the long period dwarf nova MU CentauriJan 21 2016Even among the brigher cataclysmic variables an appreciable number of objects exist about which not much is known. One of them, MU Cen, was observed as part of a small project to better characterize these neglected systems. The temporal variations of ... More
Supervised mid-level features for word image representationOct 20 2014Nov 14 2014This paper addresses the problem of learning word image representations: given the cropped image of a word, we are interested in finding a descriptive, robust, and compact fixed-length representation. Machine learning techniques can then be supplied with ... More
Removable singularities for Hölder continuous quasiregular mappings in the planeApr 20 2006We give necessary conditions for a set E to be removable for Holder continuous quasiregular mappings in the plane. We also obtain some removability results for Holder continuous mappings of finite distortion.
Some theoretical and experimental aspects of axion physicsDec 10 2015Dec 15 2015In the first part of the thesis, we revisit the Dine-Fischler-Srednicki-Zhitnisky axion model in light of the recent Higgs LHC results and electroweak precision data. This model is an extension of the two-Higgs-doublet model incorporating a PQ symmetry ... More
A Simulated Annealing Approach to Bayesian InferenceSep 17 2015A generic algorithm for the extraction of probabilistic (Bayesian) information about model parameters from data is presented. The algorithm propagates an ensemble of particles in the product space of model parameters and outputs. Each particle update ... More
Electromagnetic Induction and the Conservation of Momentum in the Spiral ParadoxDec 05 2000The inversion of cause and effect in the classic description of electromagnetism, gives rise to a conceptual error which is at the bottom of many paradoxes and exceptions. At present, the curious fact that unipolar induction or the Faraday Disc constitutes ... More
Bayesian Estimates of the Large-Scale Velocity Field in Real Space and Redshift SpaceOct 04 1993Methods for inferring the velocity field from the peculiar velocity data are described and applied to old and newer data. Inhomogeneous Malmquist bias and ways to avoid it are discussed and utilized. We infer that these biases are probably important in ... More
The CMBR SpectrumMay 22 1997A short review of the measured spectrum of the Cosmic Microwave Background Radiation (CMBR) and implications. Extensions of the Kompaneets equation and Sunyaev-Zel'dovich effect are given.
Theoretical remark on the superconductivity of metalsOct 27 2005Aug 25 2006In this paper Einstein develops some crucial ideas about superconductivity
Gauge theories on noncommutative spacesNov 29 2000I review my results about noncommutative gauge theories and about the relation of these theories to M(atrix) theory following my lecture on ICMP 2000.
Symmetry transformations in Batalin-Vilkovisky formalismOct 19 1993This short note is closely related to Sen-Zwiebach paper on gauge transformations in Batalin-Vilkovisky theory (hep-th 9309027). We formulate some conditions of physical equivalence of solutions to the quantum master equation and use these conditions ... More
Planetary nebulae in 2014: A review of researchJun 17 2015Jun 29 2015Planetary nebulae had a double anniversary in 2014, 250 year since their discovery and 150 year since the correct spectroscopic identification. This paper gives an overview of planetary nebula research published in 2014. Topics include surveys, central ... More
TV-min and Greedy Pursuit for Constrained Joint Sparsity and Application to Inverse ScatteringMay 17 2012Dec 19 2012This paper proposes a general framework for compressed sensing of constrained joint sparsity (CJS) which includes total variation minimization (TV-min) as an example. TV- and 2-norm error bounds, independent of the ambient dimension, are derived for the ... More
Remarks on QFT in the Coordinate SpaceSep 06 2016Oct 26 2016Generators of the Poincar\'e group, for a free massive scalar field, are usually expressed in the momentum space. In this work we perform a transformation of these generators into the coordinate space. This (spatial)-position space is spanned by eigenvectors ... More
Curved Space-Times from Strict Deformations?Aug 09 2016We use a deformed differential structure and the Rieffel deformation to obtain a curved metric by deforming the flat space-time. In particular, a deformed Friedmann-Robertson-Walker and an ultra-static space-time emerge from this strict deformation scheme. ... More
Implementation of the Random Forest Method for the Imaging Atmospheric Cherenkov Telescope MAGICSep 24 2007Nov 08 2007The paper describes an application of the tree classification method Random Forest (RF), as used in the analysis of data from the ground-based gamma telescope MAGIC. In such telescopes, cosmic gamma-rays are observed and have to be discriminated against ... More
On the total absolute curvature of sphere eversionsMar 22 2005Oct 04 2005This paper has been withdrawn by the author, due to an error in Proposition 2.2.
A Mechanistic Dynamic EmulatorDec 22 2011Jul 05 2012In applied sciences, we often deal with deterministic simulation models that are too slow for simulation-intensive tasks such as calibration or real-time control. In this paper, an emulator for a generic dynamic model, given by a system of ordinary non-linear ... More
Discrete-Gauss states and the generation of focussing dark beamsMar 11 2014Mar 25 2014Discrete-Gauss states are a new class of gaussian solutions of the free Schr\"odinger equation owning discrete rotational symmetry. They are obtained by acting with a discrete deformation operator onto Laguerre-Gauss modes. We present a general analytical ... More
A new classical solution in SU(2) Yang-Mills gauge theoryAug 21 2011Oct 20 2013A new classical solution of euclidean Yang-Mills gauge theory, which is governed by $\pi_4 (SU(2))$, is given. Its relationship to knot theory and Hopfions is discussed.
Massless QFT and the Newton-Wigner OperatorOct 20 2016In this work, the second-quantized version of the spatial-coordinate operator, known as the Newton-Wigner-Pryce operator, is explicitly given w.r.t. the massless scalar field. Moreover, transformations of the conformal group are calculated on eigenfunctions ... More
A Note on Semi-Algebraic Proofs and Gaussian Elimination over Prime FieldsFeb 13 2015In this note we show that unsatisfiable systems of linear equations with a constant number of variables per equation over prime finite fields have polynomial-size constant-degree semi-algebraic proofs of unsatisfiability. These are proofs that manipulate ... More
Scale- free networks in cell biologyOct 28 2005A cell's behavior is a consequence of the complex interactions between its numerous constituents, such as DNA, RNA, proteins and small molecules. Cells use signaling pathways and regulatory mechanisms to coordinate multiple processes, allowing them to ... More
Quantum curvesJan 08 2014Aug 16 2014One says that a pair (P,Q) of ordinary differential operators specify a quantum curve if [P,Q]=const. If a pair of difference operators (K,L) obey the relation KL=const LK we say that they specify a discrete quantum curve. This terminology is prompted ... More
Axiomatic conformal theory in dimensions >2 and AdS/CT correspondenceSep 27 2015May 07 2016We formulate axioms of conformal theory (CT) in dimensions $>2$ modifying Segal's axioms for two-dimensional CFT. (In the definition of higher-dimensional CFT one includes also a condition of existence of energy-momentum tensor.) We use these axioms to ... More
Space and time from translation symmetryJan 06 2006May 16 2009We show that the notions of space and time in algebraic quantum field theory arise from translation symmetry if we assume asymptotic commutativity. We argue that this construction can be applied to string theory.
Noncommutative supergeometry, duality and deformationsOct 28 2002Oct 28 2002We introduce a notion of $Q$-algebra that can be considered as a generalization of the notion of $Q$-manifold (a supermanifold equipped with an odd vector field obeying $\{Q,Q\} =0$). We develop the theory of connections on modules over $Q$-algebras and ... More
Quantum observables, Lie algebra homology and TQFTApr 25 1999Let us consider a Lie (super)algebra $G$ spanned by $T_{\alpha}$ where $T_{\alpha}$ are quantum observables in BV-formalism. It is proved that for every tensor $c^{\alpha_1...\alpha_k}$ that determines a homology class of the Lie algebra $G$ the expression ... More
Measurement of gamma and 2 beta + gammaDec 20 2004Jan 26 2005We report on the initial measurements of the angle gamma and the sum of angles 2 beta + gamma of the Unitarity Triangle. When compared with indirect information on the value of gamma from other measurements of CKM parameters, the measurement of these ... More
Nonlinear plasmonic amplification via dissipative soliplasmonsNov 07 2016In this contribution we introduce a new strategy for the compensation of plasmonic losses based on a recently proposed nonlinear mechanism: the resonant interaction between surface plasmon polaritons and spatial solitons propagating in parallel along ... More
Photometry of some neglected bright cataclysmic variables and candidatesNov 01 2016As part of an effort to better characterize bright cataclysmic variables (CVs) which have received little attention in the past light curves of four confirmed systems (CZ Aql, BO Cet, V380 Oph and EF Tuc) and one candidate (Lib 3) are analyzed. For none ... More
Massless QFT and the Newton-Wigner OperatorOct 20 2016Oct 28 2016In this work, the second-quantized version of the spatial-coordinate operator, known as the Newton-Wigner-Pryce operator, is explicitly given w.r.t. the massless scalar field. Moreover, transformations of the conformal group are calculated on eigenfunctions ... More
XMM-Newton observation of the X-ray point source population of the starburst galaxy IC342Aug 06 2003We present the results of an XMM-Newton observation of the starburst galaxy IC342. Thirty-seven X-ray point sources were detected down to a luminosity limit of $\sim 10^{37}$ \lum. Most of the sources are located near the spiral arms. The X-ray point ... More
Dirac operators, shell interactions and discontinuous gauge functions across the boundaryDec 11 2015Given a bounded smooth domain $\Omega\subset\mathbb{R}^3$, we explore the relation between couplings of the free Dirac operator $-i\alpha\cdot\nabla+m\beta$ with pure electrostatic shell potentials $\lambda\delta_{\partial\Omega}$ ($\lambda\in\mathbb{R}$) ... More
Young classes of permutationsAug 26 2010Apr 17 2012We characterise those classes of permutations having the property that for every tableau shape either every permutation of that shape or no permutation of that shape belongs to the class. The characterisation is in terms of the dominance order for partitions ... More
Invariant manifolds and the parameterization method in coupled energy harvesting piezoelectric oscillatorsSep 11 2016Oct 08 2016Energy harvesting systems based on oscillators aim to capture energy from mechanical oscillations and convert it into electrical energy. Widely extended are those based on piezoelectric materials, whose dynamics are Hamiltonian submitted to different ... More
CMB Spectral Distortions from the Scattering of Temperature AnisotropiesMar 20 2007Thomson scattering of CMBR temperature anisotropies will cause the spectrum of the CMBR to differ from blackbody even when one resolves all anisotropies. A formalism for computing the anisotropic and inhomogeneous spectral distortions of intensity and ... More
Measuring Space-Time Geometry over the AgesMay 18 2012Theorists are often told to express things in the "observational plane". One can do this for space-time geometry, considering "visual" observations of matter in our universe by a single observer over time, with no assumptions about isometries, initial ... More
Cohen-Lenstra Moments for Some Nonabelian GroupsJun 25 2016Aug 10 2016Cohen and Lenstra detailed a heuristic for the distribution of odd p-class groups for imaginary quadratic fields. One such formulation of this distribution is that the expected number of surjections from the class group of an imaginary quadratic field ... More
Fourier-Domain Fixed Point Algorithms with Coded Diffraction PatternsJun 10 2014Mar 08 2016Fourier-domain Difference Map (FDM) for phase retrieval with two oversampled coded diffraction patterns are proposed. FDM is a 3-parameter family of fixed point algorithms including Fourier-domain Hybrid-Projection-Reflection (FHPR) and Douglas-Rachford ... More
Time Reversal of Broadband Signals in a Strongly Fluctuating MIMO Channel: Stability and ResolutionSep 18 2005We analyze the time reversal of a multiple-input-multiple-output (MIMO) system in a space-frequency-selective multi-path fading channel described by the stochastic Schr\"odinger equation with a random potential in the strong-fluctuation regime. We prove ... More
Variation for singular integrals on Lipschitz graphs: L^p and endpoint estimatesOct 04 2011Let 0<n<d be integers and let H denote the n-dimensional Hausdorff measure restricted to an n-dimensional Lipschitz graph in R^d with slope strictly less than 1. For r>2, we prove that the r-variation and oscillation for Calder\'on-Zygmund singular integrals ... More
Elementary Considerations on the Interpretation of the Foundations of Quantum MechanicsJul 19 2011This paper appeared in a collection of papers titled "Scientific Papers Presented to Max Born on his retirement from the Tait Chair of Natural Philosophy in the University of Edinburgh", published in 1953 (Oliver and Boyd), pages 33-40.
Topological quantum field theoriesNov 29 2000Following my plenary lecture on ICMP2000 I review my results concerning two closely related topics: topological quantum field theories and the problem of quantization of gauge theories. I start with old results (first examples of topological quantum field ... More
Superanalogs of symplectic and contact geometry and their applications to quantum field theoryJun 17 1994The paper contains a short review of the theory of symplectic and contact manifolds and of the generalization of this theory to the case of supermanifolds. It is shown that this generalization can be used to obtain some important results in quantum field ... More
Geometry of Batalin-Vilkovisky quantizationMay 26 1992The present paper is devoted to the study of geometry of Batalin-Vilkovisky quantization procedure. The main mathematical objects under consideration are P-manifolds and SP-manifolds (supermanifolds provided with an odd symplectic structure and, in the ... More
Noncommutative Algebraic Equations and Noncommutative Eigenvalue ProblemApr 12 2000Apr 27 2000We analyze the perturbation series for noncommutative eigenvalue problem $AX=X\lambda$ where $\lambda$ is an element of a noncommutative ring, $ A$ is a matrix and $X$ is a column vector with entries from this ring. As a corollary we obtain a theorem ... More
Sigma-models having supermanifolds as target spacesJun 10 1995We study a topological sigma-model ($A$-model) in the case when the target space is an ($m_0|m_1$)-dimensional supermanifold. We prove under certain conditions that such a model is equivalent to an $A$-model having an ($m_0-m_1$)-dimensional manifold ... More
Improved Component Predictions of Batting MeasuresMay 20 2015Jun 25 2015Standard measures of batting performance such as a batting average and an on-base percentage can be decomposed into component rates such as strikeout rates and home run rates. The likelihood of hitting data for a group of players can be expressed as a ... More
Satellite-Mounted Light Sources as Photometric Calibration Standards for Ground-Based TelescopesJan 27 2011A significant and growing portion of systematic error on a number of fundamental parameters in astrophysics and cosmology is due to uncertainties from absolute photometric and flux standards. A path toward achieving major reduction in such uncertainties ... More
Graded Unification: A Framework for Interactive ProcessingJun 05 1994An extension to classical unification, called {\em graded unification} is presented. It is capable of combining contradictory information. An interactive processing paradigm and parser based on this new operator are also presented.
Quantum Mechanical Effects from Deformation TheoryJul 09 2013Feb 18 2014We consider deformations of quantum mechanical operators by using the novel construction of warped convolutions. The deformation enables us to obtain several quantum mechanical effects where electromagnetic and gravitomagnetic fields play a role. Furthermore, ... More
Self-Adjointness of Deformed Unbounded OperatorsJun 09 2015Jan 15 2016We consider deformations of unbounded operators by using the novel construction tool of warped convolutions. By using the Kato-Rellich theorem we show that unbounded self-adjoint deformed operators are self-adjoint if they satisfy a certain condition. ... More
Wedge-Local Quantum Fields on a Nonconstant Noncommutative SpacetimeJun 20 2012Within the framework of warped convolutions we deform the massless free scalar field. The deformation is performed by using the generators of the special conformal transformations. The investigation shows that the deformed field turns out to be wedge-local. ... More
Three remarks on Matula numbersMay 23 2013In SIAM Review 10, page 273, D. W. Matula described a bijection between N and the set of topological rooted trees; the number is called the Matula number of the rooted tree. The Gutman-Ivic-Matula (GIM) function g(n) computes the number of edges of the ... More
A Remark on the Omori-Yau Maximum PrincipleMar 01 2012A Riemannian manifold $M$ is said to satisfy the Omori-Yau maximum principle if for any $C^2$ bounded function $g:M\to \Bbb R$ there is a sequence $x_n\in M$, such that $\lim_{n\to \infty}g(x_n)=\sup_M g$, $ \lim_{n\to \infty}|\nabla g(x_n)|=0$ and $\limsup_{n\to ... More
Statistical mechanics of complex networksJun 06 2001Complex networks describe a wide range of systems in nature and society, much quoted examples including the cell, a network of chemicals linked by chemical reactions, or the Internet, a network of routers and computers connected by physical links. While ... More
Dynamics of coupled piezoelectric energy harvestersSep 11 2016In this article we consider an energy harvesting device given by the coupling of two piezoelastic oscillators. We write the system as two coupled duffing equations (which model the mechanical part of the piezoelastic beams) plus a perturbation. The latter ... More
Universal Numerical Encoder and Profiler Reduces Computing's Memory Wall with Software, FPGA, and SoC ImplementationsMar 20 2013In the multicore era, the time to computational results is increasingly determined by how quickly operands are accessed by cores, rather than by the speed of computation per operand. From high-performance computing (HPC) to mobile application processors, ... More
Remarks on QFT in the Coordinate SpaceSep 06 2016Generators of the Poincar\'e group, for a free massive scalar field, are usually expressed in the momentum space. In this work we perform a transformation of these generators into the coordinate space. This (spatial)-position space is spanned by eigenvectors ... More
Compressive Spectral Estimation with Single-Snapshot ESPRIT: Stability and ResolutionJul 06 2016In this paper Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) is developed for spectral estimation with single-snapshot measurement. Stability and resolution analysis with performance guarantee for Single-Snapshot ESPRIT ... More
Absolute Uniqueness of Phase Retrieval with Random IlluminationOct 23 2011Jul 20 2012Random illumination is proposed to enforce absolute uniqueness and resolve all types of ambiguity, trivial or nontrivial, from phase retrieval. Almost sure irreducibility is proved for any complex-valued object of a full rank support. While the new irreducibility ... More
Time Reversal Communication in Multi-Path Fading Channels with PinholesSep 18 2005The paper presents an analysis of the time reversal in multi-path Rayleigh-fading channels with $N$ inputs (transmitters) and $M$ outputs (receivers). The main issues addressed are the condition of statistical stability, the rate of information transfer ... More
Time lags of the flickering in cataclysmic variables as a function of wavelengthMar 10 2015Flickering is a ubiquitous phenomenon in cataclysmic variables (CVs). Although the underlying light source is one of the main contributors to the optical radiation, the mechanism leading to flickering is not understood as yet. The present study aims to ... More
Weak Lensing On the Celestial SphereSep 22 1996This paper details a description of the pattern of galaxy image distortion over the entire sky caused by the gravitational lensing which is the result of large scale inhomogeneities in our universe. We present a tensor spherical harmonic formalism to ... More
Notes on the computation of periodic orbits using Newton and Melnikov's method: Stroboscopic vs Poincaré mapOct 11 2016These notes were written during the 9th and 10th sessions of the subject Dynamical Systems II coursed at DTU (Denmark) during the Winter Semester 2015-2016. They aim to provide students with a theoretical and numerical background for the computation of ... More
Morita equivalence and dualityMay 07 1998It was shown by Connes, Douglas, Schwarz[1] that one can compactify M(atrix) theory on noncommutative torus. We prove that compactifications on Morita equivalent tori are physically equivalent. This statement can be considered as a generalization of non-classical ... More
Grassmannian and string theoryOct 16 1996Dec 02 1996Infinite-dimensional Grassmannian manifold contains moduli spaces of Riemann surfaces of all genera. This well known fact leads to a conjecture that non-perturbative string theory can be formulated in terms of Grassmannian. We present new facts supporting ... More
Gauge theories on noncommutative euclidean spacesNov 20 2001Nov 30 2001We consider gauge theories on noncommutative euclidean space . In particular, we discuss the structure of gauge group following standard mathematical definitions and using the ideas of hep-th/0102182.
Theta-functions on noncommutative toriJul 25 2001Ordinary theta-functions can be considered as holomorphic sections of line bundles over tori. We show that one can define generalized theta-functions as holomorphic elements of projective modules over noncommutative tori (theta-vectors). The theory of ... More
Noncommutative instantons: a new approachFeb 26 2001We discuss instantons on noncommutative four-dimensional Euclidean space. In commutative case one can consider instantons directly on Euclidean space, then we should restrict ourselves to the gauge fields that are gauge equivalent to the trivial field ... More
Mass loss on the Asymptotic Giant BranchMay 03 2006Mass loss on the Asymptotic Giant Branch provides the origin of planetary nebulae. This paper reviews several relevant aspects of AGB evolution: pulsation properties, mass loss formalisms and time variable mass loss, evidence for asymmetries on the AGB, ... More
Isospectral Deformations in QFT: The Massive caseMar 27 2015We consider isospectral deformations of quantum field theories by using the novel construction tool of warped convolutions. The deformation enables us to obtain a variety of models that are wedge-local and have nontrivial scattering matrices.
Relativistic Corrections to the Moyal-Weyl SpacetimeMay 26 2014Feb 04 2015We define a coordinate operator in a QFT-fashion to obtain by a deformation procedure a relativistic Moyal-Weyl spacetime. The idea is extracted from recent progress in deformation theory concerning the emergence of the quantum plane of the Landau-quantization. ... More
Complex projective structures on Kleinian groupsOct 27 1998Let M^3 be a compact, oriented, irreducible, and boundary incompressible 3-manifold. Assume that its fundamental group is without rank two abelian subgroups and its boundary is non-empty. We will show that every homomorphism from pi_1(M) to PSL(2,C) which ... More
Circumventing Heisenberg's uncertainty principle in atom interferometry tests of the equivalence principleSep 27 2015Atom interferometry tests of universality of free fall based on the differential measurement of two different atomic species provide a useful complement to those based on macroscopic masses. However, when striving for the highest possible sensitivities, ... More
Adaptive methods for PDE's: wavelets or mesh refinement?Dec 01 2002Adaptive mesh refinement techniques are nowadays an established and powerful tool for the numerical discretization of PDE's. In recent years, wavelet bases have been proposed as an alternative to these techniques. The main motivation for the use of such ... More
Small Gamma Products with Simple ValuesJul 09 2009Our main result shows that for every odd natural number n > 1 there is a partition of the rational numbers, x/2n in lowest terms, in the unit interval, the product of whose Gamma values takes the form of powers of 2 and pi.
Nonremovable sets for Hölder continuous quasiregular mappings in the planeApr 20 2006We show that for any dimension t>2(1+alpha K)/(1+K) there exists a compact set E of dimension t and a function alpha-Holder continuous on the plane, which is K-quasiregular only outside of E. To do this, we construct an explicit K-quasiconformal mapping ... More
Emergence of scaling in random networksOct 21 1999Systems as diverse as genetic networks or the world wide web are best described as networks with complex topology. A common property of many large networks is that the vertex connectivities follow a scale-free power-law distribution. This feature is found ... More