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Results for "Joachim G. Voss"

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Late-time evolution of ultracompact X-ray binariesOct 23 2012Oct 29 2012Ultracompact X-ray binaries (UCXBs) have orbital periods shorter than about 80 minutes and typically consist of a neutron star that accretes hydrogen-poor matter from a white dwarf companion. Angular momentum loss via gravitational wave radiation drives ... More
Hilbert norms for graded algebrasDec 15 1997Dec 13 2000This paper presents a solution to a problem from superanalysis about the existence of Hilbert-Banach superalgebras. Two main results are derived: 1) There exist Hilbert norms on some graded algebras (infinite-dimensional superalgebras included) with respect ... More
Long-term luminosity behavior of 14 ultracompact X-ray binariesJun 04 2012Context. X-ray binaries are usually divided in persistent and transient sources. For ultracompact X-ray binaries (UCXBs), the mass transfer rate is expected to be a strong function of orbital period, predicting persistent sources at short periods and ... More
Phase synchronization from noisy univariate signalsMay 04 2005We present methods for detecting phase synchronization of two unidirectionally coupled, self-sustained noisy oscillators from a signal of the driven oscillator alone. One method detects soft, another hard phase locking. Both are applied to the problem ... More
Identifying mediating variables with graphical models: an application to the study of causal pathways in people living with HIVJul 10 2019We empirically demonstrate that graphical models can be a valuable tool in the identification of mediating variables in causal pathways. We make use of graphical models to elucidate the causal pathway through which the treatment influences the levels ... More
Upper and Lower Bounds in Exponential Tauberian TheoremsAug 05 2009Sep 30 2009In this text we study, for positive random variables, the relation between the behaviour of the Laplace transform near infinity and the distribution near zero. A result of De Bruijn shows that $E(e^{-\lambda X}) \sim \exp(r\lambda^\alpha)$ for $\lambda\to\infty$ ... More
Very Massive Stars (VMS) in the Local UniverseFeb 08 2013Feb 20 2013Recent studies have claimed the existence of very massive stars (VMS) up to 300 solar masses in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 Msun, it is timely to discuss the status ... More
Population synthesis of classical low-mass X-ray binaries in the Galactic BulgeMay 14 2015May 28 2015Aims. We model the present-day population of 'classical' low-mass X-ray binaries (LMXBs) with neutron star accretors, which have hydrogen-rich donor stars. Their population is compared with that of hydrogen-deficient LMXBs, known as ultracompact X-ray ... More
Carbon-oxygen-neon mass nuclei in superstrong magnetic fieldsJul 15 2016Sep 09 2016The properties of $\isotope[12]{C}$, $\isotope[16]{O}$, and $\isotope[20]{Ne}$ nuclei in strong magnetic fields $B\simeq 10^{17}\,$G are studied in the context of strongly magnetized neutron stars and white dwarfs. The SKY3D code is extended to incorporate ... More
Rare events in population genetics: Stochastic tunneling in a two-locus model with recombinationDec 08 2010Feb 22 2011We study the evolution of a population in a two-locus genotype space, in which the negative effects of two single mutations are overcompensated in a high fitness double mutant. We discuss how the interplay of finite population size, $N$, and sexual recombination ... More
Linear and nonlinear time series analysis of the black hole candidate Cygnus X-1Nov 10 1999We analyze the variability in the X-ray lightcurves of the black hole candidate Cygnus X-1 by linear and nonlinear time series analysis methods. While a linear model describes the over-all second order properties of the observed data well, surrogate data ... More
Discovery of the progenitor of the type Ia supernova 2007onFeb 14 2008Type Ia supernovae are exploding stars that are used to measure the accelerated expansion of the Universe and are responsible for most of the iron ever produced. Although there is general agreement that the exploding star is a white dwarf in a binary ... More
Approximations to the Stochastic Burgers EquationMay 24 2010This article is devoted to the numerical study of various finite difference approximations to the stochastic Burgers equation. Of particular interest in the one-dimensional case is the situation where the driving noise is white both in space and in time. ... More
ScoutBot: A Dialogue System for Collaborative NavigationJul 21 2018ScoutBot is a dialogue interface to physical and simulated robots that supports collaborative exploration of environments. The demonstration will allow users to issue unconstrained spoken language commands to ScoutBot. ScoutBot will prompt for clarification ... More
On the number of cyclic transitive subgroups of a permutation groupJan 26 2015Feb 09 2015We prove an upper bound for the number of cyclic transitive subgroups in a finite permutation group and clarify the structure of the groups for which this bound becomes sharp. We also give an application in the theory of number fields.
Attractor Networks on Complex Flag ManifoldsDec 13 2008Robbin and Salamon showed that attractor-repellor networks and Lyapunov maps are equivalent concepts and illustrate this with the example of linear flows on projective spaces. In these examples the fixed points are linearly ordered with respect to the ... More
Stability of Spherically Symmetric Wave MapsMar 02 2005We study Wave Maps from R^{2+1} to the hyperbolic plane with smooth compactly supported initial data which are close to smooth spherically symmetric ones with respect to some H^{1+\mu}, \mu>0. We show that such Wave Maps don't develop singularities and ... More
On the mod-$p$ distribution of discriminants of $G$-extensionsFeb 15 2019This paper was motivated by a recent paper by Krumm and Pollack investigating modulo-$p$ behaviour of quadratic twists with rational points of a given hyperelliptic curve, conditional on the abc-conjecture. We extend those results to twisted Galois covers ... More
Computation of Hurwitz spaces and new explicit polynomials for almost simple Galois groupsDec 17 2015We compute the first explicit polynomials with Galois groups $G=P\Gamma L_3(4)$, $PGL_3(4)$, $PSL_3(4)$ and $PSL_5(2)$ over $\mathbb{Q}(t)$. Furthermore we compute the first examples of totally real polynomials with Galois groups $PGL_2(11)$, $PSL_3(3)$, ... More
Data types with symmetries and polynomial functors over groupoidsOct 02 2012Polynomial functors are useful in the theory of data types, where they are often called containers. They are also useful in algebra, combinatorics, topology, and higher category theory, and in this broader perspective the polynomial aspect is often prominent ... More
Pathologies on the Hilbert scheme of pointsDec 20 2018We prove that the Hilbert scheme of points on a higher dimensional affine space is non-reduced and has components lying entirely in characteristic p for all primes p. In fact, we show that Vakil's Murphy's Law holds up to retraction for this scheme. Our ... More
Deformations of zero-dimensional schemes and applicationsJul 30 2013Apr 02 2014In this thesis we consider the geometry of the Hilbert scheme of points in P^n, concentrating on the locus of points corresponding to the Gorenstein subschemes of P^n. New results are given, most importantly we provide tools for constructing flat families ... More
A remark on the effect of random singular two-particle interactionsJul 04 2017In this note we study a two-particle bound system (molecule) moving on the positive half-line under the influence of randomly distributed singular two-particle interactions generated by a Poisson process. We give a rigorous definition of the underlying ... More
Arason's filtration of the Witt group of dyadic valued fieldsJan 03 2019Jan 04 2019Generalizing a theorem of Springer, we construct an extended Arason filtration by subgroups for the Witt group of quadratic forms of a general valued field, relating these subgroups with Witt-like groups of the residue field, in arbitrary characteristic. ... More
On rational functions with monodromy group $M_{11}$Mar 23 2015Dec 14 2015We compute new polynomials with Galois group $M_{11}$ over $\mathbb{Q}(t)$. These polynomials stem from various families of covers of $\mathbb{P}^1\mathbb{C}$ ramified over at least 4 points. Each of these families has features that make a detailed study ... More
From Möbius inversion to renormalisationSep 04 2018This paper traces a straight line from classical M\"obius inversion to Hopf-algebraic perturbative renormalisation. This line, which is logical but not entirely historical, consists of just a few main abstraction steps, and some intermediate steps dwelled ... More
Images of function and distribution spaces under the Bargmann transformSep 18 2014Jun 08 2016We consider a broad family of test function spaces and their dual (distribution) space. The family includes Gelfand-Shilov spaces, a family of test function spaces introduced by S. Pilipovic. We deduce different characterizations of such spaces, especially ... More
Classifying local Artinian Gorenstein algebrasNov 25 2015Oct 12 2016The classification of local Artinian Gorenstein algebras is equivalent to the study of orbits of a certain non-reductive group action on a polynomial ring. We give an explicit formula for the orbits and their tangent spaces. We apply our technique to ... More
Existence of weak solutions of an unsteady thermistor problem with p-Laplacian type equationSep 06 2016We prove the existence of weak solutions to an unsteady thermistor system with p-Laplacian type equation for the electrostatic potential, where the electrical conductivity of the thermistor material is a monotone function of the electric field density. ... More
On the number of isolated eigenvalues of a pair of particles in a quantum wireDec 31 2018In this note we consider a pair of particles moving on the positive half-line with the pairing generated by a hard-wall potential. This model was first introduced in [arXiv:1604.06693] and later applied to investigate condensation of pairs of electrons ... More
Diffusive limit of a spatially-extended kinetic FitzHugh-Nagumo modelJun 19 2019We consider a spatially extended kinetic model of a FitzHugh-Nagumo neural network, with a rescaled interaction kernel. Our main purpose is to prove that its diffusive limit in the regime of strong local interactions converges towards a FitzHugh-Nagumo ... More
Bound states of two-dimensional Schrödinger-Newton equationsJul 25 2008We prove an existence and uniqueness result for ground states and for purely angular excitations of two-dimensional Schr\"{o}dinger-Newton equations. From the minimization problem for ground states we obtain a sharp version of a logarithmic Hardy-Littlewood-Sobolev ... More
Model revision inference for extensions of first order logicMay 16 2014I am Joachim Jansen and this is my research summary, part of my application to the Doctoral Consortium at ICLP'14. I am a PhD student in the Knowledge Representation and Reasoning (KRR) research group, a subgroup of the Declarative Languages and Artificial ... More
Elementary remarks on units in monoidal categoriesJul 18 2005Jun 08 2006We explore an alternative definition of unit in a monoidal category originally due to Saavedra: a Saavedra unit is a cancellative idempotent (in a 1-categorical sense). This notion is more economical than the usual notion in terms of left-right constraints, ... More
On pairs of interacting electrons in a quantum wireJan 02 2018In this paper we consider pairs of interacting electrons moving in a simple quantum wire, namely the half-line. In particular, we extend the results obtained in [arXiv:1708.03753] by allowing for contact interactions of the Lieb-Liniger type between the ... More
On the impact of surface defects on a condensate of electron pairs in a quantum wireDec 20 2017Jun 18 2018In this paper we are interested in understanding the impact of surface defects on a condensate of electron pairs in a quantum wire. Based on previous results we establish a simple mathematical model in order to account for such surface effects. For a ... More
The BAHAMAS project: the CMB--large-scale structure tension and the roles of massive neutrinos and galaxy formationDec 06 2017Mar 13 2018Recent studies have presented evidence for tension between the constraints on Omega_m and sigma_8 from the cosmic microwave background (CMB) and measurements of large-scale structure (LSS). This tension can potentially be resolved by appealing to extensions ... More
Dictionary Learning for Adaptive GPR Landmine ClassificationMay 24 2018Jun 12 2019Ground penetrating radar (GPR) target detection and classification is a challenging task. Here, we consider online dictionary learning (DL) methods to obtain sparse representations (SR) of the GPR data to enhance feature extraction for target classification ... More
The Langevin Approach: a simple stochastic method for complex phenomenaFeb 18 2015We describe a simple stochastic method, so-called Langevin approach, which enables one to extract evolution equations of stochastic variables from a set of measurements. Our method is parameter-free and it is based on the nonlinear Langevin equation. ... More
Euro-VO - Coordination of Virtual Observatory activities in EuropeJun 22 2015The European Virtual Observatory Euro-VO has been coordinating European VO activities through a series of projects co-funded by the European Commission over the last 15 years. The bulk of VO work in Europe is ensured by the national VO initiatives and ... More
Morphisms of Coloured Petri NetsAug 07 2006We introduce the concept of a morphism between coloured nets. Our definition generalizes Petris definition for ordinary nets. A morphism of coloured nets maps the topological space of the underlying undirected net as well as the kernel and cokernel of ... More
Measurement of b-Baryons with the CDF II detectorOct 02 2007We report the observation of new bottom baryon states. The most recent result is the observation of the baryon \Xi_b^- through the decay \Xi_b^- to J/\psi \Xi^-. The significance of the signal corresponds to 7.7 sigma and the \Xi_b^- mass is measured ... More
Tangency quantum cohomologyJun 20 2000Let X be a smooth projective variety. Using modified psi classes on the stack of genus zero stable maps to X, a new associative quantum product is constructed on the cohomology space of X. When X is a homogeneous variety, this structure encodes the characteristic ... More
On bound electron pairs in a quantum wireAug 12 2017May 30 2018Based on the quantum two-body problem introduced in [arXiv:1604.06693] we consider bound pairs of electrons moving on the positive half-line. The analysis is motivated by the ground-breaking work of Cooper who identified the pairing of electrons as a ... More
On a two-particles system associated to the one spatial dimensional Galilei groupMar 26 2007In [8], M.Daumens and M.Perroud studied a two Galilean free particles system by realizing the three dimensional Galilei group on its maximal coadjoint orbit. In this paper we realize a similar study for the one spatial dimesnional Galilei group. As its ... More
Characteristic numbers of rational curves with cusp or prescribed triple contactFeb 09 2001This note pursues the techniques of modified psi classes on the stack of stable maps (cf. [Graber-Kock-Pandharipande]) to give concise solutions to the characteristic number problem of rational curves in P^2 or P^1 x P^1 with a cusp or a prescribed triple ... More
Rogue waves and entropy consumptionAug 14 2017Based on data from the Japan Sea and the North Sea the occurrence of rogue waves is analyzed by a scale dependent stochastic approach, which interlinks fluctuations of waves for different spacings. With this approach we are able to determine a stochastic ... More
Cavity optoelectromechanical regenerative amplificationJul 05 2011Jun 29 2012Cavity optoelectromechanical regenerative amplification is demonstrated. An optical cavity enhances mechanical transduction, allowing sensitive measurement even for heavy oscillators. A 27.3 MHz mechanical mode of a microtoroid was linewidth narrowed ... More
Parameter-free resolution of the superposition of stochastic signalsOct 25 2015This paper presents a direct method to obtain the deterministic and stochastic contribution of the sum of two independent sets of stochastic processes, one of which is composed by Ornstein-Uhlenbeck processes and the other being a general (non-linear) ... More
On commutativity of ideal extensionsMay 14 2013In this paper we examine the commutativity of ideal extensions. We introduce methods of constructing such extensions, in particular we construct a noncommutative ring T which contains a central and idempotent ideal I such that T/I is a field. This answers ... More
Connections between Linear Systems and Convolutional CodesMay 30 2000The article reviews different definitions for a convolutional code which can be found in the literature. The algebraic differences between the definitions are worked out in detail. It is shown that bi-infinite support systems are dual to finite-support ... More
Inductive Analysis on Singular Minimal HypersurfacesAug 14 2008The present paper describes a way to relate Martin boundaries on spaces of varying topology. This enables us to approach some detailed inductive analysis of the eigenfunctions of conformal Laplacians on minimal hypersurfaces near their singularities. ... More
Solvability of Generalized Monomial GroupsJan 22 2009The solvability of monomial groups is a well-known result in character theory. Certain properties of Artin L-series suggest a generalization of these groups, namely to such groups where every irreducible character has some multiple which is induced from ... More
Cyclic Theory and the Bivariant Chern-Connes CharacterMar 31 2001We give a survey of cyclic homology/cohomology theory including a detailed discussion of cyclic theories for various classes of topological algebras. We show how to associate cyclic classes with Fredholm modules and $K$-theory classes and how to construct ... More
Hyperbolic Unfoldings of Minimal HypersurfacesMay 06 2018We study the intrinsic geometry of area minimizing (and also of almost minimizing) hypersurfaces from a new point of view by relating this subject to quasiconformal geometry. For any such hypersurface we define and construct a so-called S-structure which ... More
Categorification of Hopf algebras of rooted treesSep 27 2011Apr 28 2012We exhibit a monoidal structure on the category of finite sets indexed by P-trees for a finitary polynomial endofunctor P. This structure categorifies the monoid scheme (over Spec N) whose semiring of functions is (a P-version of) the Connes--Kreimer ... More
A note on the product of two permutations of prescribed ordersAug 10 2015Dec 16 2016We prove a conjecture by Stefan Kohl on the existence of triples of permutations of bounded degree with prescribed orders and product 1. This result leads to an existence result for covers of the complex projective line with bounded degree and prescribed ... More
$C^*$-algebras associated with the $ax+b$-semigroup over $\mathbb N$Nov 17 2006We present a $C^*$-algebra which is naturally associated to the $ax+b$-semigroup over $\mathbb N$. It is simple and purely infinite and can be obtained from the algebra considered by Bost and Connes by adding one unitary generator which corresponds to ... More
Universal Monotonicity of Eigenvalue Moments and Sharp Lieb-Thirring InequalitiesOct 09 2008Oct 13 2008We show that phase space bounds on the eigenvalues of Schr\"{o}dinger operators can be derived from universal bounds recently obtained by E. M. Harrell and the author via a monotonicity property with respect to coupling constants. In particular, we provide ... More
Radioactive 26Al from the Scorpius-Centaurus AssociationJul 26 2010The Scorpius-Centaurus association is the most-nearby group of massive and young stars. As nuclear-fusion products are ejected by massive stars and supernovae into the surrounding interstellar medium, the search for characteristic gamma-rays from radioactivity ... More
Propagating Polaritons in III-Nitride Slab WaveguidesDec 08 2016We report on III-nitride waveguides with c-plane GaN/AlGaN quantum wells in the strong light-matter coupling regime supporting propagating polaritons. They feature a normal mode splitting as large as 60 meV at low temperatures thanks to the large overlap ... More
Electronic properties of graphene antidot latticesJul 01 2009Oct 01 2009Graphene antidot lattices constitute a novel class of nano-engineered graphene devices with controllable electronic and optical properties. An antidot lattice consists of a periodic array of holes which causes a band gap to open up around the Fermi level, ... More
Characteristics of GRIFFIN high-purity germanium clover detectorsNov 14 2017The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new experimental facility for radioactive decay studies at the TRIUMF-ISAC laboratory. The performance of the 16 high-purity germanium (HPGe) clover detectors that will ... More
Analysis of SPDEs arising in path sampling part II: The nonlinear caseJan 05 2006Oct 30 2007In many applications, it is important to be able to sample paths of SDEs conditional on observations of various kinds. This paper studies SPDEs which solve such sampling problems. The SPDE may be viewed as an infinite-dimensional analogue of the Langevin ... More
Type Ia supernovae in globular clusters: observational upper limitsNov 28 2011In the dense stellar environment of the globular clusters, compact binaries are produced dynamically. Therefore the fraction of type Ia supernovae that explode in globular clusters is expected to be higher than the fraction of mass residing in these. ... More
Electromagnetic-induced fission of 238U projectile fragments, a test case for the production of spherical super-heavy nucleiOct 18 2002Isotopic series of 58 neutron-deficient secondary projectiles (205,206At, 205-209Rn, 208-212,217,218Fr, 211-223Ra, 215-226Ac, 221-229Th, 226-231Pa, 231-234U) were produced by projectile fragmentation using a 1 A GeV 238U beam. Cross sections of fission ... More
Slow-scale split-step tau-leap method for stiff stochastic chemical systemsSep 23 2017Dec 18 2018Tau-leaping is a family of algorithms for the approximate simulation of the discrete state continuous time Markov chains. Motivation for the development of such methods can be found, for instance, in the fields of chemical kinetics and systems biology. ... More
The Rate of Convergence for Approximate Bayesian ComputationNov 08 2013Jul 18 2014Approximate Bayesian Computation (ABC) is a popular computational method for likelihood-free Bayesian inference. The term "likelihood-free" refers to problems where the likelihood is intractable to compute or estimate directly, but where it is possible ... More
Indirect Visibility of Gravitational Waves in Magnetohydrodynamic PlasmasMar 17 2005We propose a mechanism to make gravitational waves (GWs) visible in the electromagnetic domain. Gravitational waves that propagate through a strongly magnetized plasma interact with the plasma through its anisotropic stress-energy tensor and excite magnetohydrodynamic ... More
Natural Cohen-Macaulayfication of simplicial affine semigroup ringsJun 29 2010Aug 07 2011Let $K$ be a field, $B$ a simplicial affine semigroup, and $C(B)$ the corresponding cone. We will present a decomposition of $K[B]$ into a direct sum of certain monomial ideals, which generalizes a construction by Hoa and St\"uckrad. We will use this ... More
A vector field method on the distorted Fourier side and decay for wave equations with potentialsJul 09 2013Jun 03 2014We study the Cauchy problem for the one-dimensional wave equation with an inverse square potential. We derive dispersive estimates, energy estimates, and estimates involving the scaling vector field, where the latter are obtained by employing a vector ... More
Pole Placement with Fields of Positive CharacteristicDec 15 2009The pole placement problem belongs to the classical problems of linear systems theory. It is often assumed that the ground field is the real numbers R or the complex numbers C. The major result over the complex numbers derived in 1981 by Brockett and ... More
Polynomial functors and polynomial monadsJun 26 2009Mar 06 2010We study polynomial functors over locally cartesian closed categories. After setting up the basic theory, we show how polynomial functors assemble into a double category, in fact a framed bicategory. We show that the free monad on a polynomial endofunctor ... More
Ultrafast Energy Transfer with Competing Channels: Non-equilibrium Foerster and Modified Redfield TheoriesJan 30 2017We derive equations of motion for the reduced density matrix of a molecular system which undergoes energy transfer dynamics competing with fast internal conversion channels. Environmental degrees of freedom of such a system have no time to relax to quasi-equilibrium ... More
Entropy of shifts on higher-rank graph C*-algebrasMay 09 2006Jan 16 2008Let O_{Lambda} be a higher rank graph C*-algebra of rank r. For every tuple p of non-negative integers there is a canonical completely positive map Phi^p on O_{Lambda} and a subshift T^p on the path space X of the graph. We show that ht(Phi^p)=h(T^p), ... More
The Fubini product and its applicationsMar 15 2016The Fubini product of operator spaces provide a powerful tool for analysing properties of tensor products. In this paper we review the the theory of Fubini products and apply it to the problem of computing invariant parts of dynamical systems. In particular, ... More
The emptiness formation probability correlation in homogeneous and dimerized XX chainsApr 22 2009May 27 2009We review some known properties of the "emptiness formation probability" correlation which we have calculated numerically for spin-1/2 XX chains with constant (homogeneous) or alternating (dimerized) nearest-neighbor coupling and an external field (in ... More
Record-breaking temperatures reveal a warming climateMay 18 2010Nov 25 2010We present a mathematical analysis of records drawn from independent random variables with a drifting mean. To leading order the change in the record rate is proportional to the ratio of the drift velocity to the standard deviation of the underlying distribution. ... More
Structural Relaxation and Mode Coupling in a Simple Liquid: Depolarized Light Scattering in BenzeneApr 08 2002Apr 18 2002We have measured depolarized light scattering in liquid benzene over the whole accessible temperature range and over four decades in frequency. Between 40 and 180 GHz we find a susceptibility peak due to structural relaxation. This peak shows stretching ... More
Higher-Order Compositional Modeling of Three-phase Flow in 3D Fractured Porous Media Using Cross-flow Equilibrium ApproachApr 04 2013Numerical simulation of multiphase compositional flow in fractured porous media, when all the species can transfer between the phases, is a real challenge. Despite the broad applications in hydrocarbon reservoir engineering and hydrology, a compositional ... More
Detecting atmospheric neutrino oscillations in the ATLAS detector at CERNMay 17 2007Nov 16 2007We discuss the possibility to study oscillations of atmospheric neutrinos in the ATLAS experiment at CERN. Due to the large total detector mass, a significant number of events is expected, and during the shutdown phases of the LHC, reconstruction of these ... More
Impurity spin relaxation in S=1/2 XX chainsMay 20 1999Nov 08 1999Dynamic autocorrelations $<S_i^{\alpha}(t) S_i^{\alpha}>$ (\alpha=x,z) of an isolated impurity spin in a S=1/2 XX chain are calculated. The impurity spin, defined by a local change in the nearest-neighbor coupling, is either in the bulk or at the boundary ... More
Restrictions on the geometry of the periodic vorticity equationSep 06 2010We prove that several evolution equations arising as mathematical models for fluid motion cannot be realized as metric Euler equations on the Lie group of all smooth and orientation-preserving diffeomorphisms on the circle. These include the quasi-geostrophic ... More
Coherence for weak unitsJul 27 2009We define weak units in a semi-monoidal 2-category $\CC$ as cancellable pseudo-idempotents: they are pairs $(I,\alpha)$ where $I$ is an object such that tensoring with $I$ from either side constitutes a biequivalence of $\CC$, and $\alpha: I \tensor I ... More
Anisotropic Superfluidity in the Two-Species Polar Fermi GasAug 03 2010Oct 20 2010We study the superfluid pairing in a two-species gas of heteronuclear fermionic molecules with equal density. The interplay of the isotropic s-wave interaction and anisotropic long-range dipolar interaction reveals rich physics. We find that the single-particle ... More
Comment on "Fourier transform of hydrogen-type atomic orbitals'', Can. J. Phys. Vol.\ 96, 724 - 726 (2018) by N. Yükçü and S. A. YükçüApr 29 2019Podolsky and Pauling (Phys. Rev. \textbf{34}, 109 - 116 (1929)) were the first ones to derive an explicit expression for the Fourier transform of a bound-state hydrogen eigenfunction. Y\"{u}k\c{c}\"{u} and Y\"{u}k\c{c}\"{u}, who were apparently unaware ... More
A note on spectral triples and quasidiagonalityOct 29 2008Nov 04 2008Spectral triples (of compact type) are constructed on arbitrary separable quasidiagonal C*-algebras. On the other hand an example of a spectral triple on a non-quasidiagonal algebra is presented.
On symmetries of nonlinear systems in state representation and application of invariant feedback designJun 21 2012Symmetries of nonlinear control systems in state representation are considered. To this end, a geometric approach to ordinary differential equations is advocated. Invariant feedback laws for systems with Lie symmetries, i.e. feedback laws that preserve ... More
Patterson--Sullivan distributions for rank one symmetric spaces of the noncompact typeSep 11 2009Sep 18 2009There is a remarkable relation between two kinds of phase space distributions associated to eigenfunctions of the Laplacian of a compact hyperbolic manifold: It was observed in \cite{AZ} that for compact hyperbolic surfaces $X_{\Gamma}=\Gamma\backslash\mathbb{H}$ ... More
Potential Theory on Gromov Hyperbolic Manifolds of Bounded GeometryMay 06 2018In the 1980s Alano Ancona developed a profound potential theory on Gromov hyperbolic manifolds of bounded geometry. Since then, such hyperbolic spaces have become basic in geometry, topology and group theory. In this paper we make Ancona's original work, ... More
Algebraic K-theory and locally convex algebrasMar 21 2005We consider functors from the category of locally convex algebras to abelian groups and prove invariance under smooth homotopies for weakly J-stable algebras, where J is a harmonic operator ideal. This applies in particular to negative algebraic K-theory. ... More
Noncommutative topological entropy of endomorphisms of Cuntz algebrasApr 28 2008Oct 31 2008Noncommutative topological entropy estimates are obtained for polynomial gauge invariant endomorphisms of Cuntz algebras, generalising known results for the canonical shift endomorphisms. Exact values for the entropy are computed for a class of permutative ... More
The Dynamics of Initiative in Communication NetworksApr 21 2016Human social interaction is often intermittent. Two acquainted persons can have extended periods without social interaction punctuated by periods of repeated interaction. In this case, the repeated interaction can be characterized by a seed initiative ... More
On Lennard-Jones-type potentials on the half-lineMay 14 2018Aug 31 2018In this paper we study a particle under the influence of a Lennard-Jones potential moving in a simple quantum wire modelled by the positive half-line. Despite its physical significance, this potential is only rarely studied in the literature and due to ... More
On a two-particle bound system on the half-lineApr 22 2016Jun 06 2016In this paper we provide an extension of the model discussed in [arXiv:1504.08283] describing two singularly interacting particles on the half-line. In this model, the particles are interacting only whenever at least one particle is situated at the origin. ... More
Two interacting particles on the half-lineApr 30 2015Jan 07 2016In the case of compact quantum graphs, many-particle models with singular two-particle interactions where introduced in [arXiv:1207.5648, arXiv:1112.4751] to provide a paradigm for further studies on many-particle quantum chaos. In this note, we discuss ... More
Spin-Orbit States of Neutron WavepacketsFeb 22 2016We propose a method to prepare an entangled spin-orbit state between the spin and the orbital angular momenta of a neutron wavepacket. This spin-orbit state is created by passing neutrons through the center of a quadrupole magnetic field, which provides ... More
Towards Enhanced Usability of IT Security Mechanisms - How to Design Usable IT Security Mechanisms Using the Example of Email EncryptionJun 23 2015Nowadays, advanced security mechanisms exist to protect data, systems, and networks. Most of these mechanisms are effective, and security experts can handle them to achieve a sufficient level of security for any given system. However, most of these systems ... More
Small data global regularity for half-wave mapsOct 04 2016We formulate the half-wave maps problem with target $S^2$ and prove global regularity in sufficiently high spatial dimensions for a class of small critical data in Besov spaces.
Non-generic blow-up solutions for the critical focusing NLS in 1-dAug 29 2005This paper addresses the existence of codimension one stable manifolds for the pseudo-conformal blow-up solution for critical one-dimensional NLS. By the work of Perelman and Merle, Raphael, the blow-up rate of these solutions is far from the generic ... More