Results for "Florian J. Kolb"

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Formation of Acetaldehyde on CO-rich IcesApr 12 2019The radicals HCO and CH$_3$ on carbon monoxide ice surfaces were simulated using density functional theory. Their binding energy on amorphous CO ice shows broad distributions, with approximative average values of 500 K for HCO and 200 K for CH$_3$. If ... More
Tracing a Z-track in the M31 X-ray Binary RX J0042.6+4115Sep 26 2003Four XMM-Newton observations of the core of M31, spaced at 6 month intervals, show that the brightest point X-ray source, RX J0042.6+4115, has a 0.4-10 keV luminosity of ~5 10^38 erg/s, and exhibits significant variability in intensity and X-ray spectrum ... More
Reorganization of a dense granular assembly: the `unjamming response function'Aug 04 2003Jan 14 2004We investigate the mechanical properties of a static dense granular assembly in response to a local forcing. To this end, a small cyclic displacement is applied on a grain in the bulk of a 2D disordered packing under gravity and the displacement fields ... More
Synthetic Spectral Analysis of the Hot Component in the S-Type Symbiotic Variable EG AndromedaJul 26 2004We have applied grids of NLTE high gravity model atmospheres and optically thick accretion disk models for the first time to archival IUE and FUSE spectra of the S-type symbiotic variable EG And taken at superior spectroscopic conjunction when Rayleigh ... More
Gravitational production of super-Hubble-mass particles: an analytic approachDec 01 2018Dec 08 2018Through a mechanism similar to perturbative particle scattering, particles of mass $m_\chi$ larger than the Hubble expansion rate $H_\mathrm{inf}$ during inflation can be gravitationally produced at the end of inflation without the exponential suppression ... More
On Non-parametric Estimation of the Lévy Kernel of Markov ProcessesApr 17 2012May 12 2013We consider a recurrent Markov process which is an It\^o semi-martingale. The L\'evy kernel describes the law of its jumps. Based on observations X(0),X({\Delta}),...,X(n{\Delta}), we construct an estimator for the L\'evy kernel's density. We prove its ... More
NGC300 X-1 and IC10 X-1: a new breed of black hole binary?Jul 03 2008[ABRIDGED] IC10 X-1 has recently been confirmed as a black hole (BH) + Wolf-Rayet (WR) X-ray binary, and NGC300 X-1 is thought to be. IC10 X-1 and NGC300 X-1 have similar X-ray properties, with luminosities ~10^38 erg/s, and orbital periods ~30 hr. We ... More
Superheavy dark matterFeb 05 1998May 26 1998We show that in large-field inflationary scenarios, superheavy (many orders of magnitude larger than the weak scale) dark matter will be produced in cosmologically interesting quantities if superheavy stable particles exist in the mass spectrum. We show ... More
Are ultrahigh energy cosmic rays signals of supersymmetry?Jul 02 1997Dec 19 1997We investigate the possibility that cosmic rays of energy larger than the Greisen-Zatsepin-Kuzmin cutoff are not nucleons, but a new stable, massive, hadron that appears in many extensions of the standard model. We focus primarily on the S^0, a uds-gluino ... More
Nonthermal Supermassive Dark MatterMay 27 1998Sep 25 1998We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting ... More
Resonance Reaction in Diffusion-Influenced Bimolecular ReactionsFeb 24 2016We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate ... More
Quantum symmetric Kac-Moody pairsJul 25 2012Sep 29 2014The present paper develops a general theory of quantum group analogs of symmetric pairs for involutive automorphism of the second kind of symmetrizable Kac-Moody algebras. The resulting quantum symmetric pairs are right coideal subalgebras of quantized ... More
Quantum Symmetric Pairs and the Reflection EquationDec 27 2005Sep 06 2006It is shown that central elements in G. Letzter's quantum group analogs of symmetric pairs lead to solutions of the reflection equation. This clarifies the relation between Letzter's approach to quantum symmetric pairs and the approach taken by M. Noumi, ... More
Radial part calculations for affine sl2 and the Heun KZB-heat equationOct 02 2013In the present paper we determine the radial part of the Casimir element for the Lie algebra affine sl2 with respect to the Chevalley involution. The resulting operator is identified with a blend of the Inozemtsev Hamiltonian and the KZB-heat equation ... More
Binary evolution with relativistic jetsOct 20 1998Relativistic jets can extract mass-energy from a black hole. In semi-detached black hole binaries the jet ejection process constitutes a `consequential angular momentum loss' (CAML) process. The effect of this jet-induced CAML is to lower the transfer ... More
Braided module categories via quantum symmetric pairsMay 11 2017Let $\mathfrak{g}$ be a finite dimensional complex semisimple Lie algebra. The finite dimensional representations of the quantized enveloping algebra $U_q({\mathfrak g})$ form a braided monoidal category $O_{int}$. We show that the category of finite ... More
The AS-Cohen-Macaulay property for quantum flag manifolds of minuscule weightJul 10 2007It is shown that quantum homogeneous coordinate rings of generalised flag manifolds corresponding to minuscule weights, their Schubert varieties, big cells, and determinantal varieties are AS-Cohen-Macaulay. The main ingredient in the proof is the notion ... More
Multi-Conjugate Adaptive Optics images of the Trapezium ClusterSep 25 2007Multi-Conjugate Adaptive Optics (MCAO) combines the advantages of standard adaptive optics, which provides high contrast and high spatial resolution, and of wide field ~1' imaging. Up to recently, MCAO for astronomy was limited to laboratory experiments. ... More
Discovery and modelling of disc precession in the M31 X-ray binary Bo 158?Nov 02 2005The low mass X-ray binary (LMXB) associated with the M31 globular cluster Bo 158 is known to exhibit intensity dips on a ~2.78 hr period. This is due to obscuration of the X-ray source on the orbital period by material on the outer edge of the accretion ... More
Discovery of disc precession in the M31 dipping X-ray binary Bo 158Mar 11 2005Nov 08 2005We present results from three XMM-Newton observations of the M31 low mass X-ray binary XMMU J004314.4+410726.3 (Bo 158), spaced over 3 days in 2004, July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic intensity dips were previously ... More
On the order reduction of entropy stable DGSEM for the compressible Euler equationsJan 17 2019Is the experimental order of convergence lower when using the entropy stable DGSEM-LGL variant? Recently, a debate on the question of the convergence behavior of the entropy stable nodal collocation discontinuous Galerkin spectral element method (DGSEM) ... More
The systemic velocities of four long-period cataclysmic variable starsJan 31 2002Although a large number of orbital periods of cataclysmic variable stars (CVs) have been measured, comparison of period and luminosity distributions with evolutionary theory is affected by strong selection effects. A test has been discovered which is ... More
Black hole hunting in the Andromeda GalaxySep 06 2004We present a new technique for identifying stellar mass black holes in low mass X-ray binaries (LMXBs), and apply it to XMM-Newton observations of M31. We examine X-ray time series variability seeking power density spectra (PDS) typical of LMXBs accreting ... More
Isocurvature constraints on gravitationally produced superheavy dark matterNov 16 2004We show that the isocurvature perturbations imply that the gravitationally produced superheavy dark matter must have masses larger than few times the Hubble expansion rate at the end of inflation. This together with the bound on tensor to scalar contribution ... More
Estimation of atmospheric turbulence parameters from Shack-Hartmann wavefront sensor measurementsNov 20 2018The estimation of atmospheric turbulence parameters is of relevance for: a) site evaluation & characterisation; b) prediction of the point spread function; c) live assessment of error budgets and optimisation of adaptive optics performance; d) optimisation ... More
Cavity OptomechanicsMar 04 2013We review the field of cavity optomechanics, which explores the interaction between electromagnetic radiation and nano- or micromechanical motion. This review covers the basics of optical cavities and mechanical resonators, their mutual optomechanical ... More
A CURE for noisy magnetic resonance images: Chi-square unbiased risk estimationJun 15 2011In this article we derive an unbiased expression for the expected mean-squared error associated with continuously differentiable estimators of the noncentrality parameter of a chi-square random variable. We then consider the task of denoising squared-magnitude ... More
Nonlinear Eigenmodes of a Polariton Harmonic OscillatorJan 28 2015We investigate theoretically the quantum oscillator-like states recently observed experimentally in polariton condensates (Nat. Phys. 8, 190 (2012)). We consider a complex Gross-Pitaevskii type model which includes the effects of self-interactions, and ... More
A Volterra-series approach to stochastic nonlinear dynamics: The Duffing oscillator driven by white noiseJan 22 2019The Duffing oscillator is a paradigm of bistable oscillatory motion in physics, engineering, and biology. Time series of such oscillations are often observed experimentally in a nonlinear system excited by a spontaneously fluctuating force. One is then ... More
Braid group action and root vectors for the $q$-Onsager algebraJun 27 2017Jun 12 2019We define two algebra automorphisms $T_0$ and $T_1$ of the $q$-Onsager algebra $B_c$, which provide an analog of G. Lusztig's braid group action for quantum groups. These automorphisms are used to define root vectors which give rise to a PBW basis for ... More
Spectral Analysis of Diffusions with Jump BoundaryJan 13 2011In this paper we consider one-dimensional diffusions with constant coefficients in a finite interval with jump boundary and a certain deterministic jump distribution. We use coupling methods in order to identify the spectral gap in the case of a large ... More
Compression, inversion, and approximate PCA of dense kernel matrices at near-linear computational complexityJun 07 2017Mar 22 2019Dense kernel matrices $\Theta \in \mathbb{R}^{N \times N}$ obtained from point evaluations of a covariance function $G$ at locations $\{ x_{i} \}_{1 \leq i \leq N}$ arise in statistics, machine learning, and numerical analysis. For covariance functions ... More
Population synthesis of wide binary millisecond pulsarsAug 18 2002Four evolutionary channels leading to the formation of wide binary millisecond pulsars are investigated. The majority of binary millisecond pulsars are found to descend from systems in which the most massive component undergoes a common-envelope phase ... More
The orbital period distribution of wide binary millisecond pulsarsApr 02 2004Apr 06 2004We present results of a binary population synthesis study on the orbital period distribution of wide binary millisecond pulsars forming through four evolutionary channels. In three of the channels, the progenitor of the millisecond pulsar undergoes a ... More
The bar involution for quantum symmetric pairsSep 17 2014Jan 29 2016We construct a bar involution for quantum symmetric pair coideal subalgebras $B_{\mathbf{c},\mathbf{s}}$ corresponding to involutive automorphisms of the second kind of symmetrizable Kac-Moody algebras. To this end we give unified presentations of these ... More
Symmetric pairs for Nichols algebras of diagonal type via star productsJan 02 2019We construct symmetric pairs for Drinfeld doubles of pre-Nichols algebras of diagonal type and determine when they possess an Iwasawa decomposition. This extends G. Letzter's theory of quantum symmetric pairs. Our results can be uniformly applied to Kac-Moody ... More
Right coideal subalgebras of the Borel part of a quantized enveloping algebraOct 19 2009For the Borel part of a quantized enveloping algebra we classify all right coideal subalgebras for which the intersection with the coradical is a Hopf algebra. The result is expressed in terms of characters of the subalgebras $U^+[w]$ of the quantized ... More
Maximum principle satisfying CWENO schemes for non-local conservation lawsMar 14 2018Oct 29 2018Central WENO schemes are a natural candidate for higher-order schemes for non-local conservation laws, since the underlying reconstructions do not only provide single point values of the solution but a complete (high-order) reconstruction in every time ... More
Homogeneous right coideal subalgebras of quantized enveloping algebrasSep 19 2011For a quantized enveloping algebra of a complex semisimple Lie algebra with deformation parameter not a root of unity, we classify all homogeneous right coideal subalgebras. Any such right coideal subalgebra is determined uniquely by a triple consisting ... More
Prospects for detecting asteroseismic binaries in Kepler dataFeb 11 2014Asteroseismology may in principle be used to detect unresolved stellar binary systems comprised of solar-type stars and/or red giants. This novel method relies on the detection of the presence of two solar-like oscillation spectra in the frequency spectrum ... More
On the late spectral types of cataclysmic variable secondariesApr 21 2000We investigate why the spectral type of most cataclysmic variable (CV) secondaries is significantly later than that of a ZAMS star with the same mean density. Using improved stellar input physics, tested against observations of low-mass stars at the bottom ... More
Brown Dwarfs and the Cataclysmic Variable Period MinimumJun 28 1999Using improved, up-to-date stellar input physics tested against observations of low-mass stars and brown dwarfs we calculate the secular evolution of low-mass donor cataclysmic variables (CVs), including those which form with a brown dwarf donor. Our ... More
Factorisation of quasi K-matrices for quantum symmetric pairsApr 09 2018The theory of quantum symmetric pairs provides a universal K-matrix which is an analogue of the universal R-matrix for quantum groups. The main ingredient in the construction of the universal K-matrix is a quasi K-matrix which has so far only been constructed ... More
On the Bernstein-Gelfand-Gelfand resolution for Kac-Moody algebras and quantized enveloping algebrasMay 17 2006A Bernstein-Gelfand-Gelfand resolution for arbitrary Kac-Moody algebras and arbitrary subsets of the set of simple roots is proven. Moreover, quantum group analogs of the Bernstein-Gelfand-Gelfand resolution for symmetrizable Kac-Moody algebras are established. ... More
The Locally Finite Part of the Dual Coalgebra of Quantized Irreducible Flag ManifoldsJan 22 2003Jun 18 2003The notion of locally finite part of the dual coalgebra of certain quantized coordinate rings is introduced. In the case of irreducible flag manifolds this locally finite part is shown to coincide with a natural quotient coalgebra V of U_q(g). On the ... More
Quasistationary distributions for one-dimensional diffusions with singular boundary pointsSep 08 2014Mar 30 2018In the present work we characterize the existence of quasistationary distributions for diffusions on $(0,\infty)$ allowing singular behavior at $0$ and $\infty$. If absorption at 0 is certain, we show that there exists a quasistationary distribution as ... More
Universal K-matrix for quantum symmetric pairsJul 22 2015Jan 29 2016Let $\mathfrak{g}$ be a symmetrizable Kac-Moody algebra and let $U_q(\mathfrak{g})$ denote the corresponding quantized enveloping algebra. In the present paper we show that quantum symmetric pair coideal subalgebras $B_{c,s}$ of $U_q(\mathfrak{g})$ have ... More
Braid group actions on coideal subalgebras of quantized enveloping algebrasFeb 21 2011We construct braid group actions on coideal subalgebras of quantized enveloping algebras which appear in the theory of quantum symmetric pairs. In particular, we construct an action of the semidirect product of Z^n and the classical braid group in n strands ... More
Pattern phase diagram for 2D arrays of coupled limit-cycle oscillatorsJan 07 2015Arrays of coupled limit-cycle oscillators represent a paradigmatic example for studying synchronization and pattern formation. They are also of direct relevance in the context of currently emerging experiments on nano- and optomechanical oscillator arrays. ... More
Cosmological Bounds to the Magnetic Moment of Heavy Tau NeutrinosMar 12 1996The magnetic moment of tau neutrinos in the MeV mass range may be large enough to modify the cosmological freeze-out calculation and determine the tau-neutrino relic density. In this paper we revisit such a possibility. We calculate the evolution and ... More
Preheating and symmetry restoration in collisions of vacuum bubblesFeb 19 1996In first-order inflation a phase transition is completed by the collisions of expanding true-vacuum bubbles. If bubble collisions produce large numbers of soft scalar particles carrying quantum numbers associated with a spontaneously broken symmetry, ... More
Tensions and correlations in $|V_{cb}|$ determinationsAug 23 2017Sep 06 2017Recently several papers extracted $|V_{cb}|$ using the Belle measurement of the exclusive $\bar B \to D^* \ell\bar\nu$ unfolded differential decay rates, available for the first time. Depending on the theoretical inputs, some of the fits yield higher ... More
A Decomposition-Based Approach to Reasoning about Free Space Path-Connectivity for Rigid Objects in 2DOct 27 2017In this paper, we compute a conservative approximation of the path-connected components of the free space of a rigid object in a 2D workspace in order to solve two closely related problems: to determine whether there exists a collision-free path between ... More
Free-Stream Preservation for Curved Geometrically Non-Conforming Discontinuous Galerkin Spectral ElementsSep 13 2018The under integration of the volume terms in the discontinuous Galerkin spectral element approximation introduces errors at non-conforming element faces that do not cancel and lead to free-stream preservation errors. We derive volume and face conditions ... More
A versatile construction of Bell inequalities for the multipartite scenarioAug 31 2018Local measurements acting on entangled quantum states give rise to a rich correlation structure in the multipartite scenario. We introduce a versatile technique to build families of Bell inequalities witnessing different notions of multipartite nonlocality ... More
Quasi-free Compton Scattering from the Deuteron and Nucleon PolarizabilitiesMar 06 2000Jun 28 2000Cross sections for quasi-free Compton scattering from the deuteron were measured for incident energies of 236--260 MeV at the laboratory angle -135 degrees. The recoil nucleons were detected in a liquid-scintillator array situated at 20 degrees. The measured ... More
An optimal Borsuk-Ulam theorem for products of spheres and Stiefel manifoldsFeb 03 2019We give a new, simplified proof of a general Borsuk--Ulam theorem for a product of spheres, originally due to Ramos. That is, we show the non-existence of certain $(\mathbb{Z}/2)^k$-equivariant maps from a product of $k$ spheres to the unit sphere in ... More
Critical Fields of Nb$_3$Sn Prepared for Superconducting CavitiesOct 31 2018Apr 16 2019Nb$_3$Sn is currently the most promising material other than niobium for future superconducting radiofrequency cavities. Critical fields above 120 mT in pulsed operation and about 80 mT in CW have been achieved in cavity tests. This is large compared ... More
Local chain ordering in amorphous polymer melts: Influence of chain stiffnessJan 22 1999Molecular dynamics simulation of a generic polymer model is applied to study melts of polymers with different types of intrinsic stiffness. Important static observables of the single chain such as gyration radius or persistence length are determined. ... More
Dielectric sensing by charging energy modulation in a nano-granular metalApr 14 2014Several sensing concepts using nanostructures prepared by focused electron beam induced deposition have been developed over the last years. Following work on highly miniaturized Hall sensors for magnetic sensing with soft magnetic Co, strain and force ... More
On the Time-Dependent Analysis of Gamow DecayNov 24 2010Jul 01 2011Gamow's explanation of the exponential decay law uses complex "eigenvalues" and exponentially growing "eigenfunctions". This raises the question, how Gamow's description fits into the quantum mechanical description of nature, which is based on real eigenvalues ... More
A combined first and second order traffic network modelMar 12 2019Second order macroscopic traffic flow models are well-known to be able to reproduce the so-called capacity drop effect, i.e., the phenomenon that the outflow of a congested region is substantially lower than the maximum achievable flow in this particular ... More
Geometric Ergodicity of a Hypoelliptic Diffusion Modelling The Melt-Spinning Process of Nonwoven MaterialsDec 28 2011We analyze the large time behavior of a stochastic model for the lay-down of fibers on a conveyor belt in the production process of nonwovens. It is shown, that under weak conditions this degenerate diffusion process is strong mixing, confirming a conjecture ... More
Hand Tracking based on Hierarchical Clustering of Range DataOct 25 2011Fast and robust hand segmentation and tracking is an essential basis for gesture recognition and thus an important component for contact-less human-computer interaction (HCI). Hand gesture recognition based on 2D video data has been intensively investigated. ... More
On the long time behavior of stochastic Schroedinger evolutionsNov 12 2008Feb 13 2009We discuss the time evolution of the wave function which is solution of a stochastic Schroedinger equation describing the dynamics of a free quantum particle subject to spontaneous localizations in space. We prove global existence and uniqueness of solutions. ... More
Low Redshift Baryon Acoustic Oscillation Measurement from the Reconstructed 6-degree Field Galaxy SurveyMar 05 2018Low redshift measurements of Baryon Acoustic Oscillations (BAO) test the late time evolution of the Universe and are a vital probe of Dark Energy. Over the past decade both the 6-degree Field Galaxy Survey (6dFGS) and Sloan Digital Sky Survey (SDSS) have ... More
The BR1 Scheme is Stable for the Compressible Navier-Stokes EquationsApr 12 2017Apr 09 2018We show how to modify the original Bassi and Rebay scheme (BR1) [F. Bassi and S. Rebay, A High Order Accurate Discontinuous Finite Element Method for the Numerical Solution of the Compressible Navier-Stokes Equations, Journal of Computational Physics, ... More
On a third order CWENO boundary treatment with application to networks of hyperbolic conservation lawsMar 01 2017Dec 13 2017High order numerical methods for networks of hyperbolic conservation laws have recently gained increasing popularity. Here, the crucial part is to treat the boundaries of the single (one-dimensional) computational domains in such a way that the desired ... More
On the Dipole Approximation with Error EstimatesSep 06 2013May 12 2017The dipole approximation is employed to describe interactions between atoms and radiation. It essentially consists of neglecting the spatial variation of the external field over the atom. Heuristically, this is justified by arguing that the wavelength ... More
Residuum-Condition Diagram and Reduction of Over-Complete Endmember-SetsSep 26 2018Extracting reference spectra, or endmembers (EMs) from a given multi- or hyperspectral image, as well as estimating the size of the EM set, plays an important role in multispectral image processing. In this paper, we present condition-residuum-diagrams. ... More
Modeling and simulation of gas networks coupled to power gridsDec 29 2018In this paper, a mathematical framework for the coupling of gas networks to electric grids is presented to describe in particular the transition from gas to power. The dynamics of the gas flow are given by the isentropic Euler equations, while the power ... More
On the proof of the dipole approximationSep 06 2013The dipole approximation is widely used to study the interaction of atoms and Lasers. Employing it essentially means to replace the Laser's vector potential A(r,t) in the Hamiltonian by A(0,t). Heuristically this is justified under usual experimental ... More
On the reheating stage after inflationJul 18 2003We point out that inflaton decay products acquire plasma masses during the reheating phase following inflation. The plasma masses may render inflaton decay kinematicaly forbidden, causing the temperature to remain frozen for a period at a plateau value. ... More
Lorentz invariance violation in top-down scenarios of ultrahigh energy cosmic ray creationJun 29 2003Jan 28 2004The violation of Lorentz invariance (LI) has been invoked in a number of ways to explain issues dealing with ultrahigh energy cosmic ray (UHECR) production and propagation. These treatments, however, have mostly been limited to examples in the proton-neutron ... More
Relating Spectral Indices to Tensor and Scalar Amplitudes in InflationMar 01 1994Mar 19 1994Within an expansion in slow-roll inflation parameters, we derive the complete second-order expressions relating the ratio of tensor to scalar density perturbations and the spectral index of the scalar spectrum. We find that ``corrections'' to previously ... More
GUT Baryogenesis after PreheatingJun 07 1996Oct 24 1996At the end of inflation the universe is frozen in a near zero-entropy state with energy density in a coherent scalar field and must be ``defrosted'' to produce the observed entropy and baryon number. We propose that the baryon asymmetry is generated by ... More
Understanding selection effects in observed samples of cataclysmic variablesOct 21 2006Large differences between the properties of the known sample of cataclysmic variable stars (CVs) and the predictions of the theory of binary star evolution have long been recognised. However, because all existing CV samples suffer from strong selection ... More
Why Low-Mass Black-Hole Binaries Are TransientMay 06 1997We consider transient behavior in low-mass X-ray binaries. In short-period neutron-star systems (orbital period less than ~ 1d) irradiation of the accretion disk by the central source suppresses this except at very low mass transfer rates. Formation constraints ... More
On a stochastic Trotter formula with application to spontaneous localization modelsMar 21 2011We consider the relation between so called continuous localization models - i.e. non-linear stochastic Schr\"odinger evolutions - and the discrete GRW-model of wave function collapse. The former can be understood as scaling limit of the GRW process. The ... More
Supervised Deep Kriging for Single-Image Super-ResolutionDec 10 2018We propose a novel single-image super-resolution approach based on the geostatistical method of kriging. Kriging is a zero-bias minimum-variance estimator that performs spatial interpolation based on a weighted average of known observations. Rather than ... More
Recursion Relations for Long-Range Integrable Spin Chains with Open Boundary ConditionsJan 04 2012Apr 26 2012It is well known that integrable charges for short-range (e.g. nearest-neighbor) spin chains with periodic boundary conditions can be recursively generated by a so-called boost operator. In the past, this iterative construction has been generalized to ... More
On the Structure of Monodromy Algebras and Drinfeld DoublesSep 18 1996Oct 11 1996We give a review and some new relations on the structure of the monodromy algebra (also called loop algebra) associated with a quasitriangular Hopf algebra H. It is shown that as an algebra it coincides with the so-called braided group constructed by ... More
Local cohomology and F-stabilityApr 28 2009Jun 25 2009We study the relationship between the Frobenius stability of an Artinian module over an F-injective ring and its stable part.
On the 2-Abelian Complexity of the Thue-Morse WordApr 15 2014Jun 02 2015We show that the 2-abelian complexity of the infinite Thue-Morse word is 2-regular, and other properties of the 2-abelian complexity, most notably that it is a concatenation of palindromes of increasing length. We also show sharp bounds for the length ... More
Improved Delsarte bounds for spherical codes in small dimensionsJan 27 2005Mar 10 2008We present an extension of the Delsarte linear programming method. For several dimensions it yields improved upper bounds for kissing numbers and for spherical codes. Musin's recent work on kissing numbers in dimensions three and four can be viewed in ... More
The Galois action on M-Origamis and their Teichmüller curvesAug 28 2014We consider a rather special class of translation surfaces (called M-Origamis in this work) that are obtained from dessins by a construction introduced by Martin M\"oller. We give a new proof with a more combinatorial flavour of M\"oller's theorem that ... More
A Probabilistic Look at Conservative Growth-Fragmentation EquationsSep 08 2016Nov 02 2016In this note, we consider general growth-fragmentation equations from a probabilistic point of view. Using Foster-Lyapunov techniques, we study the recurrence of the associated Markov process depending on the growth and fragmentation rates. We prove the ... More
Random colorings and automorphism breaking in locally finite graphsApr 24 2013A colouring of a graph G is called distinguishing if its stabiliser in Aut G is trivial. It has been conjectured that, if every automorphism of a locally finite graph moves infinitely many vertices, then there is a distinguishing 2-colouring. We study ... More
Bounds for the annealed return probability on large finite percolation clustersNov 30 2008Aug 26 2012Bounds for the expected return probability of the delayed random walk on finite clusters of an invariant percolation on transitive unimodular graphs are derived. They are particularly suited for the case of critical Bernoulli percolation and the associated ... More
Optimal regularity for two-dimensional Pfaffian systems and the fundamental theorem of surface theoryApr 16 2019We prove that a Pfaffian system with coefficients in the critical space $L^2_\mathrm{loc}$ on a simply connected open subset of $\mathbb{R}^2$ has a non-trivial solution in $W^{1,2}_\mathrm{loc}$ if the coefficients are antisymmetric and satisfy a compatibility ... More
Invariance of the BFV-complexDec 12 2008Nov 21 2010The BFV-formalism was introduced to handle classical systems, equipped with symmetries. It associates a differential graded Poisson algebra to any coisotropic submanifold $S$ of a Poisson manifold $(M,\Pi)$. However the assignment (coisotropic submanifold) ... More
The MMT API: A Generic MKM SystemJun 13 2013The MMT language has been developed as a scalable representation and interchange language for formal mathematical knowledge. It permits natural representations of the syntax and semantics of virtually all declarative languages while making MMT-based MKM ... More
A Framework for an Ego-centered and Time-aware Visualization of Relations in Arbitrary Data RepositoriesSep 27 2010Understanding constellations in large data collections has become a common task. One obstacle a user has to overcome is the internal complexity of these repositories. For example, extracting connected data from a normalized relational database requires ... More
p-Adic Lifting Problems and Derived EquivalencesFeb 08 2011Jan 08 2012For two derived equivalent $k$-algebras $\bar\Lambda$ and $\bar\Gamma$, we introduce a correspondence between $\OO$-orders reducing to $\bar\Lambda$ and $\OO$-orders reducing to $\bar\Gamma$. We outline how this may be used to transfer properties like ... More
Reverse mathematics of the finite downwards closed subsets of $\mathbb{N}^k$ ordered by inclusionOct 04 2016Oct 05 2016We show that the well-partial orderedness of the finite downwards closed subsets of $\mathbb{N}^k$ ,ordered by inclusion, is equivalent to the well-foundedness of the ordinal $\omega^{\omega^\omega}$. This was conjectured to be the case by Hatzikiriakou ... More
Vortex formation and dynamics in two-dimensional driven-dissipative condensatesJul 23 2016We investigate the real-time evolution of lattice bosons in two spatial dimensions whose dynamics is governed by a Markovian quantum master equation. We derive the generalization of the truncated Wigner approximation for open quantum many-body systems ... More
Images of isogeny classes on modular elliptic curvesJul 20 2004Let K be a number field and E/K a modular elliptic curve, with modular parametrization $X_0(N) \to E$ defined over K. The purpose of this note is to study the images in E of classes of isogenous points in X_0(N).
On the $k$-Semispray of Nonlinear Connections in $k$-Tangent Bundle GeometryJan 05 2016In this paper we present a method by which is obtained a sequence of $k$-semisprays and two sequences of nonlinear connections on the $k$-tangent bundle $T^kM$, starting from a given one. Interesting particular cases appear for Lagrange and Finsler spaces ... More
Breaking graph symmetries by edge colouringsApr 27 2016The distinguishing index $D'(G)$ of a graph $G$ is the least number of colours needed in an edge colouring which is not preserved by any non-trivial automorphism. Broere and Pil\'sniak conjectured that if every non-trivial automorphism of a countable ... More
Almost complex structures on the cotangent bundleJul 04 2005Jan 04 2006We construct some lift of an almost complex structure to the cotangent bundle, using a connection on the base manifold. This generalizes the complete lift defined by I.Sato and the horizontal lift introduced by K.Yano and S.Ishihara. We study some geometric ... More