Results for "Jakob Birkedal Wagner"

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A deep learning approach to identify local structures in atomic-resolution transmission electron microscopy imagesFeb 08 2018Recording atomic-resolution transmission electron microscopy (TEM) images is becoming increasingly routine. A new bottleneck is then analyzing this information, which often involves time-consuming manual structural identification. We have developed a ... More
Step-Indexed Logical Relations for Probability (long version)Jan 12 2015Jan 13 2015It is well-known that constructing models of higher-order probabilistic programming languages is challenging. We show how to construct step-indexed logical relations for a probabilistic extension of a higher-order programming language with impredicative ... More
Two for the Price of One: Lifting Separation Logic AssertionsAug 29 2012Sep 20 2012Recently, data abstraction has been studied in the context of separation logic, with noticeable practical successes: the developed logics have enabled clean proofs of tricky challenging programs, such as subject-observer patterns, and they have become ... More
Relaxing the Upper Bound on the Mass of the Lightest Supersymmetric Higgs BosonAug 30 2004Jan 11 2005We present a class of supersymmetric models in which the lightest Higgs-boson mass can be as large as a few hundred GeV (200 - 300 GeV) while the successful MSSM prediction for gauge coupling unification is preserved. The theories are formulated on a ... More
Little Supersymmetry and the Supersymmetric Little Hierarchy ProblemApr 22 2004Apr 29 2004The current experimental lower bound on the Higgs mass significantly restricts the allowed parameter space in most realistic supersymmetric models, with the consequence that these models exhibit significant fine-tuning. We propose a solution to this `supersymmetric ... More
On the birational section conjecture with local conditionsMar 14 2012Sep 17 2015A birationally liftable Galois section s of a hyperbolic curve X/k over a number field k yields an adelic point x(s) in the smooth completion of X. We show that x(s) is X-integral outside a set of places of Dirichlet density 0, or s is cuspidal. The proof ... More
The Brauer-Manin obstruction for sections of the fundamental groupOct 26 2009We establish Grothendieck's section conjecture for an open subset of the Reichardt-Lind curve, and introduce the notion of a Brauer-Manin obstruction for sections of the fundamental group extension.
A monodromy criterion for extending curvesAug 23 2004Nov 10 2004A family of proper smooth curves of genus $\geq 2$, parametrised by an open dense subset $U$ of a normal variety $S$, extends to $S$ if the natural map $\pi_1(U) \to \pi_1(S)$ on fundamental groups is an isomorphism. The criterion of this note is actually ... More
Affine anabelian curves in positive characteristicJun 18 2002An investigation of morphisms that coincide topologically is used to generalize to all characteristics and partly reprove Tamagawa's theorem on the Grothendieck conjecture in anabelian geometry for affine hyperbolic curves. The theorem now deals with ... More
The Role of Type III Factors in Quantum Field TheoryNov 17 2004Dec 04 2004One of von Neumann's motivations for developing the theory of operator algebras and his and Murray's 1936 classification of factors was the question of possible decompositions of quantum systems into independent parts. For quantum systems with a finite ... More
A logarithmic view towards semistable reductionMay 18 2003The geometric condition of T. Saito for trivial action of the wild monodromy of a smooth proper curve over the generic point of a trait is transformed to the condition of logarithmic smooth reduction. The proof emphasizes methods and results from logarithmic ... More
Uniform central limit theorems for the Grenander estimatorNov 24 2014Jun 26 2015We consider the Grenander estimator that is the maximum likelihood estimator for non-increasing densities. We prove uniform central limit theorems for certain subclasses of bounded variation functions and for H\"older balls of smoothness s>1/2. We do ... More
Discovering and Proving Infinite Binomial Sums IdentitiesJul 07 2015Oct 29 2015We consider binomial and inverse binomial sums at infinity and rewrite them in terms of a small set of constants, such as powers of $\pi$ or $\log(2)$. In order to perform these simplifications, we view the series as specializations of generating series. ... More
On the period-index problem in light of the section conjectureFeb 28 2008Period and index of a curve $X/K$ over a $p$-adic local field $K$ such that the fundamental group $\pi_1(X/K)$ admits a splitting are shown to be powers of $p$. As a consequence, examples of curves over number fields are constructed where having sections ... More
Confidence sets in nonparametric calibration of exponential Lévy modelsFeb 29 2012Sep 19 2013Confidence intervals and joint confidence sets are constructed for the nonparametric calibration of exponential L\'evy models based on prices of European options. To this end, we show joint asymptotic normality in the spectral calibration method for the ... More
Polar sets of anisotropic Gaussian random fieldsAug 03 2012This paper studies polar sets of anisotropic Gaussian random fields, i.e. sets which a Gaussian random field does not hit almost surely. The main assumptions are that the eigenvalues of the covariance matrix are bounded from below and that the canonical ... More
Topics in the Mathematical Physics of Cold Bose GasesFeb 04 2014Feb 14 2014In these notes of six lectures on selected topics in the theory of cold, dilute Bose gases, presented at the 5th Warsaw School of Statistical Physics in June 2013, the following topics are discussed: 1) The concept of BEC, 2) the ground state energy of ... More
Non-equilibrium steady states of stochastic processes with intermittent resettingOct 27 2015Stochastic processes that are randomly reset to an initial condition serve as a showcase to investigate non-equilibrium steady states. However, all existing results have been restricted to the special case of memoryless resetting protocols. Here, we obtain ... More
Weil-Châtelet divisible elements in Tate-Shafarevich groups I: The Bashmakov problem for elliptic curves over QJun 21 2011Aug 21 2013For an abelian variety A over a number field k we discuss the maximal divisibile subgroup of H^1(k,A) and its intersection with the subgroup Sha(A/k). The results are most complete for elliptic curves over Q.
Homotopy theory of symmetric powersOct 16 2015Oct 29 2015We introduce the symmetricity notions of symmetric h-monoidality, symmetroidality, and symmetric flatness. As shown in our paper arXiv:1410.5675, these properties lie at the heart of the homotopy theory of colored symmetric operads and their algebras. ... More
Analytical approximations for spiral wavesJan 26 2013Sep 20 2013We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency $\Omega$ and core radius $R_{0}$. ... More
A uniform central limit theorem and efficiency for deconvolution estimatorsAug 03 2012We estimate linear functionals in the classical deconvolution problem by kernel estimators. We obtain a uniform central limit theorem with $\sqrt{n}$-rate on the assumption that the smoothness of the functionals is larger than the ill-posedness of the ... More
Adaptive confidence bands for Markov chains and diffusions: Estimating the invariant measure and the driftDec 22 2014Jul 07 2016As a starting point we prove a functional central limit theorem for estimators of the invariant measure of a geometrically ergodic Harris-recurrent Markov chain in a multi-scale space. This allows to construct confidence bands for the invariant density ... More
Geometric Modular Action, Wedge Duality and Lorentz Covariance are Equivalent for Generalized Free FieldsOct 20 1999The Tomita-Takesaki modular groups and conjugations for the observable algebras of space-like wedges and the vacuum state are computed for translationally covariant, but possibly not Lorentz covariant, generalized free quantum fields in arbitrary space-time ... More
Market Mechanism Design for Profitable On-Demand Transport ServicesJan 07 2015On-demand transport services in the form of dial-a-ride and taxis are crucial parts of the transport infrastructure in all major cities. However, not all on-demand transport services are equal. In particular, not-for-profit dial-a-ride services with coordinated ... More
Higgs Boson Searches at Hadron CollidersApr 13 2005The investigation of the dynamics responsible for electroweak symmetry breaking is one of the prime tasks of experiments at present and future colliders. Experiments at the Tevatron ppbar Collider and at the CERN Large Hadron Collider (LHC) must be able ... More
Convolutional Neural FabricsJun 08 2016Jun 09 2016Despite the success of convolutional neural networks, selecting the optimal architecture for a given task remains an open problem. Instead of aiming to select a single optimal architecture, we propose a $"$fabric$"$ that embeds an exponentially large ... More
Asymptotic Exactness of Magnetic Thomas-Fermi TheoryAug 24 2003We consider the grand canonical pressure for Coulombic matter with nuclear charges $\sim Z$ in a magnetic field $B$ and at nonzero temperature. We prove that its asymptotic limit as $Z\to\infty$ with $B/Z^3\to 0$ can be obtained by minimizing a Thomas-Fermi ... More
Nonparametric Bayesian posterior contraction rates for discretely observed scalar diffusionsOct 19 2015Mar 29 2016We consider nonparametric Bayesian inference in a reflected diffusion model $dX_t = b (X_t)dt + \sigma(X_t) dW_t,$ with discretely sampled observations $X_0, X_\Delta, \dots, X_{n\Delta}$. We analyse the nonlinear inverse problem corresponding to the ... More
Option calibration of exponential Lévy models: Confidence intervals and empirical resultsFeb 27 2012Oct 17 2012Observing prices of European put and call options, we calibrate exponential L\'evy models nonparametrically. We discuss the efficient implementation of the spectral estimation procedures for L\'evy models of finite jump activity as well as for self-decomposable ... More
More on the pressing down gameMay 24 2009Dec 06 2010We investigate the pressing down game and its relation to the Banach Mazur game. In particular we show: Consistently, there is a nowhere precipitous normal ideal $I$ on $\aleph_2$ such that player nonempty wins the pressing down game of length $\aleph_1$ ... More
Weil-Châtelet divisible elements in Tate-Shafarevich groups II: On a question of CasselsAug 21 2013For an abelian variety A over a number field k we discuss the divisibility in H^1(k,A) of elements of the subgroup Sha(A/k). The results are most complete for elliptic curves over Q.
Oversampling of wavelet frames for real dilationsApr 13 2012We generalize the Second Oversampling Theorem for wavelet frames and dual wavelet frames from the setting of integer dilations to real dilations. We also study the relationship between dilation matrix oversampling of semi-orthogonal Parseval wavelet frames ... More
Anabelian geometry with etale homotopy typesApr 04 2015Jul 12 2016Anabelian geometry with etale homotopy types generalizes in a natural way classical anabelian geometry with etale fundamental groups. We show that, both in the classical and the generalized sense, any point of a smooth variety over a field k which is ... More
Modules over the de Rham cohomology spectrumNov 30 2016We show that the bounded derived category of regular holonomic D-modules on a smooth variety is equivalent to the homotopy catgory of compact (or constructible) modules over the motivic ring spectrum $H_{dR}$ representing algebraic de Rham cohomology. ... More
Guarded Cubical Type TheoryNov 28 2016This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, ... More
Muller's ratchet with overlapping generationsFeb 14 2013Mar 25 2013Muller's ratchet is a paradigmatic model for the accumulation of deleterious mutations in a population of finite size. A click of the ratchet occurs when all individuals with the least number of deleterious mutations are lost irreversibly due to a stochastic ... More
The Ground State Energy of a Dilute Two-dimensional Bose GasFeb 06 2000The ground state energy per particle of a dilute, homogeneous, two-dimensional Bose gas, in the thermodynamic limit is shown rigorously to be $E_0/N = (2\pi \hbar^2\rho /m){|\ln (\rho a^2)|^{-1}}$, to leading order, with a relative error at most ${\rm ... More
The Ground State Energy of a Dilute Bose GasOct 20 1999Aug 20 2000According to a formula that was put forward many decades ago the ground state energy per particle of an interacting, dilute Bose gas at density $\rho$ is $2\pi\hbar^2\rho a/m$ to leading order in $\rho a^3\ll 1$, where $a$ is the scattering length of ... More
Explosion phenomena in stochastic coagulation-fragmentation modelsAug 25 2005First we establish explosion criteria for jump processes with an arbitrary locally compact separable metric state space. Then these results are applied to two stochastic coagulation-fragmentation models--the direct simulation model and the mass flow model. ... More
Boundary Harnack principle for the absolute value of a one-dimensional subordinate Brownian motion killed at $0$Jul 26 2016We prove the Harnack inequality and boundary Harnack principle for the absolute value of a one-dimensional recurrent subordinate Brownian motion killed upon hitting $0$, when $0$ is regular for itself and the Laplace exponent of the subordinator satisfies ... More
Labeled trees, maps, and an algebraic identityJun 16 2011Jun 23 2011We give a short and direct proof of a remarkable identity that arises in the enumeration of labeled trees with respect to their indegree sequence, where all edges are oriented from the vertex with lower label towards the vertex with higher label. This ... More
AGN Observations in the GeV/TeV Energy Range with the MAGIC TelescopeJun 29 2007MAGIC currently is the largest imaging atmospheric Cerenkov telescope world-wide. Since 2004, gamma-ray emission from several active galactic nuclei in the GeV/TeV energy range has been detected, some of which were newly discovered as very-high energy ... More
Synoptic studies of seventeen blazars detected in very high-energy gamma-raysNov 20 2007Jan 30 2008Since 2002, the number of detected blazars at gamma-ray energies above 100 GeV has more than doubled. I study 17 blazars currently known to emit E>100 GeV gamma rays. Their intrinsic energy spectra are reconstructed by removing extragalactic background ... More
Fermionic fields in the pseudoparticle approachAug 17 2007The pseudoparticle approach is a numerical method to compute path integrals without discretizing spacetime. The basic idea is to consider only those field configurations, which can be represented as a linear superposition of a small number of localized ... More
Dealing With Curious Players in Secure NetworksApr 02 2004In secure communications networks there are a great number of user behavioural problems, which need to be dealt with. Curious players pose a very real and serious threat to the integrity of such a network. By traversing a network a Curious player could ... More
Extending Characters of Fixed Point AlgebrasNov 23 2011Sep 09 2015A dynamical system is a triple $(A,G,\alpha)$, consisting of a unital locally convex algebra $A$, a topological group $G$ and a group homomorphism $\alpha:G\rightarrow\Aut(A)$, which induces a continuous action of $G$ on $A$. Further, a unital locally ... More
On the noncommutative spin geometry of the standard Podles sphere and index computationsJul 23 2007Sep 04 2008The purpose of the paper is twofold: First, known results of the noncommutative spin geometry of the standard Podles sphere are extended by discussing Poincare duality and orientability. In the discussion of orientability, Hochschild homology is replaced ... More
Hierarchical models for neural population dynamics in the presence of non-stationarityOct 12 2014Neural population activity often exhibits rich variability and temporal structure. This variability is thought to arise from single-neuron stochasticity, neural dynamics on short time-scales, as well as from modulations of neural firing properties on ... More
Search for Single-Top Production at CDFMay 21 2007This article reports on recent searches for single-top-quark production by the CDF collaboration at the Tevatron using a data set that corresponds to an integrated luminosity of 955 pb^-1. Three different analyses techniques are employed, one using likelihood ... More
Existence of Minkowski spaceSep 20 2016Physics textbooks present Minkowski space as an almost pure mathematical construct, without any explicit restriction on a domain where it is applicable in physics. Meanwhile, its physical meaning cannot but follow the same premises as those which underlies ... More
A First Synoptic Blazar Study Comprising Thirteen Blazars Visible in E>100 GeV Gamma-RaysJun 29 2007Since 2002, the number of detected blazars at E_\gamma > 100 GeV has more than doubled. I study all currently known BL Lac-type objects with published energy spectra. Their intrinsic energy spectra are reconstructed by removing extragalactic background ... More
Boundary Conditions for Electron Flow in Graphene in the Hydrodynamic RegimeSep 23 2015Graphene has generated a lot of research interest due to its special properties, which include a hydrodynamic regime. It is not yet clear however which boundary condition such a hydrodynamic current flow satisfies. The aim of this paper is to investigate ... More
Modelling traffic flow fluctuationsNov 02 2004By analyzing empirical time headway distributions of traffic flow, a hypothesis about the underlying stochastic process can be drawn. The results found lead to the assumption that the headways $T_i$ of individual vehicles follow a linear stochastic process ... More
Top Quark Cross-Section Measurements at the TevatronDec 02 2003Run II of the Tevatron collider at Fermilab is well under way and data samples larger than those of Run I are at hand. In this contribution I summarize the current status of cross-section measurements for top-quark pair production at the CDF and D0 experiments. ... More
Probing Pauli Blocking Factors in Quantum Pumps with Broken Time-Reversal SymmetryJun 21 2000A recently demonstrated quantum electron pump is discussed within the framework of photon-assisted tunneling. Due to lack of time-reversal symmetry, different results are obtained for the pump current depending on whether or not final-state Pauli blocking ... More
Properties of confining gauge field configurations in the pseudoparticle approachOct 23 2006The pseudoparticle approach is a numerical method to approximate path integrals in SU(2) Yang-Mills theory. Path integrals are computed by summing over all gauge field configurations, which can be represented by a linear superposition of a small number ... More
Exchange Currents in Radiative Hyperon DecaysJun 15 1998A short overview of motivations and successes of two-body exchange currents between constituent quarks for electromagnetic hadron observables like charge radii, magnetic and quadrupole moments is given. We then predict and analyze exchange current effects ... More
Exploring Quantum Gravity with Very-High-Energy Gamma-Ray Instruments - Prospects and LimitationsJan 20 2009Some models for quantum gravity (QG) violate Lorentz invariance and predict an energy dependence of the speed of light, leading to a dispersion of high-energy gamma-ray signals that travel over cosmological distances. Limits on the dispersion from short-duration ... More
Volatility Cluster and HerdingJul 11 2002Stock markets can be characterized by fat tails in the volatility distribution, clustering of volatilities and slow decay of their time correlations. For an explanation models with several mechanisms and consequently many parameters as the Lux-Marchesi ... More
The XL-mHG Test For Enrichment: A Technical ReportJul 28 2015Sep 24 2015The minimum hypergeometric test (mHG) is a powerful nonparametric hypothesis test to detect enrichment in ranked binary lists. Here, I provide a detailed review of its definition, as well as the algorithms used in its implementation, which enable the ... More
A Comparison of Secret Sharing Schemes Based on Latin Squares and RSAAug 19 2003Oct 16 2004In recent years there has been a great deal of work done on secret sharing scehemes. Secret Sharing Schemes allow for the division of keys so that an authorised set of users may access information. In this paper we wish to present a critical comparison ... More
Fibre product approach to index pairings for the generic Hopf fibration of SU_q(2)Feb 23 2009A fibre product construction is used to give a description of quantum line bundles over the generic Podles spheres by gluing two quantum discs along their boundaries. Representatives of the corresponding $K_0$-classes are given in terms of 1-dimensional ... More
Censored subordinate Brownian motionAug 03 2016We examine three equivalent constructions of a censored rotationally symmetric L\'{e}vy process on an open set $D$; via the corresponding Dirichlet form, through the Feynman-Kac transform of the L\'{e}vy process killed outside of $D$ and from the same ... More
Asymptotics of generalised trinomial coefficientsMay 24 2012Jul 01 2012It is shown how to obtain an asymptotic expansion of the generalised central trinomial coefficient $[x^n](x^2 + bx + c)^n$ by means of singularity analysis, thus proving a conjecture of Zhi-Wei Sun.
Correlated Variability in BlazarsAug 19 2008Blazars are thought to emit highly-collimated outflows, so-called jets. By their close alignment to our line of sight, relativistic beaming effects enable us to observe these jets over the whole electromagnetic spectrum up to TeV energies, making them ... More
Tail estimates for sums of variables sampled from a random walkAug 30 2006Dec 25 2007We prove tail estimates for variables $\sum_i f(X_i)$, where $(X_i)_i$ is the trajectory of a random walk on an undirected graph (or, equivalently, a reversible Markov chain). The estimates are in terms of the maximum of the function $f$, its variance, ... More
Exchange currents in radiative hyperon decays and hyperon charge radiiOct 06 1998Radiative decays of decuplet hyperons and octet hyperon charge radii are evaluated in a chiral constituent quark model emphasizing the role of exchange currents. Exchange currents largely cancel for the M1 decay amplitudes, while they dominate the E2 ... More
Fermions in the pseudoparticle approachApr 23 2007The pseudoparticle approach is a numerical technique to compute path integrals without discretizing spacetime. The basic idea is to integrate over those field configurations, which can be represented by a sum of a fixed number of localized building blocks ... More
Classes of confining gauge field configurationsAug 08 2006Dec 18 2006We present a numerical method to compute path integrals in effective SU(2) Yang-Mills theories. The basic idea is to approximate the Yang-Mills path integral by summing over all gauge field configurations, which can be represented as a linear superposition ... More
Free Group Actions from the Viewpoint of Dynamical SystemsNov 23 2011In this paper we present a new characterization of free group actions (in classical differential geometry), involving dynamical systems and representations of the corresponding transformation groups. In fact, given a dynamical system, we provide conditions ... More
Evaluating the Strength of Genomic Privacy MetricsJul 20 2016The genome is a unique identifier for human individuals. The genome also contains highly sensitive information, creating a high potential for misuse of genomic data (for example, genetic discrimination). In this paper, I investigated how genomic privacy ... More
How human drivers control their vehicleJan 10 2006The data presented here show that human drivers apply a discrete noisy control mechanism to drive their vehicle. A car-following model built on these observations, together with some physical limitations (crash-freeness, acceleration), led to non-Gaussian ... More
Generalised model-independent characterisation of strong gravitational lenses I: Theoretical foundationsDec 06 2016We extend the model-independent approach to characterise strong gravitational lenses of \cite{bib:Wagner} to its most general form to leading order by using the orientation angles of a set of multiple images with respect to their connection line(s) in ... More
Transitive endomorphisms with critical pointsAug 24 2016We show that a non-wandering endomorphism of the torus with invertible linear part without invariant directions and for which the critical points are in some sense generic is transitive. This improves a result of Andersson by allowing critical points ... More
Charge Fluctuations as Thermometer for Heavy-Ion CollisionsNov 15 2013We present a determination of freeze-out conditions in heavy-ion collisions based on ratios of cu- mulants of net electric charge fluctuations obtained from lattice QCD. These ratios can reliably be calculated for a wide range of chemical potential values ... More
Forces between static-light mesonsAug 09 2010The isospin, spin and parity dependent potential of a pair of static-light mesons is computed using Wilson twisted mass lattice QCD with two flavors of degenerate dynamical quarks. From the results a simple rule can be deduced stating, which isospin, ... More
Groups in simple theoriesApr 25 1997Groups definable in simple theories retain the chain conditions and decomposition properties known from stable groups, up to commensurability. In the small case, if a generic type of G is not foreign to some type q, there is a q-internal quotient. In ... More
The Use of Application Scanners in Software Product Quality AssessmentNov 21 2016Software development needs continuous quality control for a timely detection and removal of quality problems. This includes frequent quality assessments, which need to be automated as far as possible to be feasible. One way of automation in assessing ... More
A Geometric Approach to Noncommutative Principal BundlesAug 01 2011From a geometrical point of view it is, so far, not sufficiently well understood what should be a "noncommutative principal bundle". Still, there is a well-developed abstract algebraic approach using the theory of Hopf algebras. An important handicap ... More
Asymptotics of Toeplitz operators and applications in TQFTJun 08 2011In this paper we provide a review of asymptotic results of Toeplitz operators and their applications in TQFT. To do this we review the differential geometric construction of the Hitchin connection on a prequantizable compact symplectic manifold. We use ... More
Automorphism fixed points in the moduli space of semistable bundlesMay 09 2002Given an automorphism of a smooth complex algebraic curve, there is an induced action on the moduli space of semi-stable rank 2 holomorphic bundles with fixed determinant. We give a complete description of the fixed variety in terms of moduli spaces of ... More
Complexity Hierarchies and Higher-order Cons-free Term RewritingNov 30 2016Constructor rewriting systems are said to be cons-free if, roughly, constructor terms in the right-hand sides of rules are subterms of the left-hand sides; the computational intuition is that rules cannot build new data structures. In programming language ... More
Measuring Dark Matter at CollidersSep 20 2005Sep 26 2005We investigate the need and prospects for measuring dark matter properties at particle collider experiments. We discuss the connections between the inferred properties of particle dark matter and the physics that is expected to be uncovered by the Large ... More
Winning the pressing down game but not Banach MazurSep 25 2006Feb 17 2007Let $S$ be the set of those $\alpha\in\omega_2$ that have cofinality $\omega_1$. It is consistent relative to a measurable that the nonempty player wins the pressing down game of length $\omega_1$, but not the Banach Mazur game of length $\omega+1$ (both ... More
Effects of higher dimension operators on the Standard Model Higgs sectorNov 12 2015Nov 18 2015We study the effect of higher dimension operators on the electroweak finite temperature phase transition in two sectors of the Standard Model. Firstly, the Higgs-Yukawa sector, consisting of the Higgs doublet and the massive Standard Model fermions, is ... More
Shaping wave patterns in reaction-diffusion systemsMay 16 2014Dec 12 2014We present a method to control the two-dimensional shape of traveling wave solutions to reaction-diffusion systems, as e.g. interfaces and excitation pulses. Control signals that realize a pre-given wave shape are determined analytically from nonlinear ... More
The Intersection Type Unification ProblemNov 17 2016The intersection type unification problem is an important component in proof search related to several natural decision problems in intersection type systems. It is unknown and remains open whether the unification problem is decidable. We give the first ... More
Distribution and fragmentation functions in a spectator modelJul 14 1997Quark distribution and spectator functions are estimated in a diquark spectator model. The representation of the functions in terms of non-local operators together with the rather simple model allow estimates for the yet experimentally undetermined functions, ... More
Statistics of Extreme Waves in Random MediaNov 18 2013Waves traveling through random media exhibit random focusing that leads to extremely high wave intensities even in the absence of nonlinearities. Although such extreme events are present in a wide variety of physical systems and the statistics of the ... More
A singular, admissible extension which splits algebraically, but not strongly, of the algebra of bounded operators on a Banach spaceMar 14 2016Let $E$ be the Banach space constructed by Read (J. London Math. Soc. 1989) such that the Banach algebra $\mathscr{B}(E)$ of bounded operators on $E$ admits a discontinuous derivation. We show that $\mathscr{B}(E)$ has a singular, admissible extension ... More
Structure and vibrational properties of the PTCDA/Ag(111) interface: Bilayer vs. monolayerJan 23 2018The structural and vibrational properties of metal-organic interfaces have been examined by means of infrared (IR) absorption spectroscopy and density functional theory (DFT) with an approach accounting for long-range dispersive interactions. We focus ... More
Rigidity of the Laughlin liquidSep 13 2016Nov 30 2016We consider general N-particle wave functions that have the form of a product of the Laughlin state with filling factor $1/\ell$ and an analytic function of the N variables. This is the most general form of a wave function that can arise through a perturbation ... More
Shearlets and Optimally Sparse ApproximationsJun 07 2011Aug 05 2011Multivariate functions are typically governed by anisotropic features such as edges in images or shock fronts in solutions of transport-dominated equations. One major goal both for the purpose of compression as well as for an efficient analysis is the ... More
Compactly Supported ShearletsSep 22 2010Nov 22 2010Shearlet theory has become a central tool in analyzing and representing 2D data with anisotropic features. Shearlet systems are systems of functions generated by one single generator with parabolic scaling, shearing, and translation operators applied ... More
The Intersection Type Unification ProblemNov 17 2016Nov 22 2016The intersection type unification problem is an important component in proof search related to several natural decision problems in intersection type systems. It is unknown and remains open whether the unification problem is decidable. We give the first ... More
Towards a bulk description of higher spin SYKFeb 05 2018We consider on the bulk side extensions of the Sachdev--Ye--Kitaev (SYK) model to Yang--Mills and higher spins. To this end we study generalizations of the Jackiw--Teitelboim (JT) model in the BF formulation. Our main goal is to obtain generalizations ... More
Cosmological constant as confining U(1) charge in two-dimensional dilaton gravityJun 26 2014The cosmological constant is treated as a thermodynamical parameter in the framework of two-dimensional dilaton gravity. We find that the cosmological constant behaves as a U(1) charge with a confining potential, and that such potentials require a novel ... More
Black holes and thermodynamics - The first half centuryFeb 20 2014Mar 17 2014Black hole thermodynamics emerged from the classical general relativistic laws of black hole mechanics, summarized by Bardeen-Carter-Hawking, together with the physical insights by Bekenstein about black hole entropy and the semi-classical derivation ... More
Numerical performance of the parabolized ADM (PADM) formulation of General RelativityDec 08 2007Dec 11 2007In a recent paper the first coauthor presented a new parabolic extension (PADM) of the standard 3+1 Arnowitt, Deser, Misner formulation of the equations of general relativity. By parabolizing first-order ADM in a certain way, the PADM formulation turns ... More