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Results for "Philipp Bender"

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Evolutionary Mechanics: new engineering principles for the emergence of flexibility in a dynamic and uncertain worldJan 21 2011Engineered systems are designed to deftly operate under predetermined conditions yet are notoriously fragile when unexpected perturbations arise. In contrast, biological systems operate in a highly flexible manner; learn quickly adequate responses to ... More
On singularities in B-orbit closures of 2-nilpotent matricesNov 11 2013Nov 26 2013This paper deals with singularities of closures of $2$-nilpotent Borel conjugacy classes in either a $\text{GL}_n$-conjugacy class or in the nilpotent cone of $\text{GL}_n$. In the latter case we construct a resolution of singularities, in the former ... More
The magnetic structure factor of correlated nanoparticle moments in small-angle neutron scatteringApr 12 2019Here, we derive expressions for the magnetic small-angle neutron scattering (SANS) cross section of magnetic nanoparticle ensembles under consideration of a magnetic structure factor. We show that for structurally disordered ensembles with correlated ... More
Ito's Formula for Gaussian Processes with Stochastic DiscontinuitiesJan 30 2018We introduce a Skorokhod type integral and prove an Ito formula for a wide class of Gaussian processes which may exhibit stochastic discontinuities. Our Ito formula unifies and extends the classical one for general (i.e., possibly discontinuous) Gaussian ... More
Global Fluctuations in General Beta Dyson Brownian MotionOct 25 2006We consider a system of diffusing particles on the real line in a quadratic external potential and with repulsive electrostatic interaction. The empirical measure process is known to converge weakly to a deterministic measure-valued process as the number ... More
Optimal Shape of a BlobMar 08 2007This paper presents the solution to the following optimization problem: What is the shape of the two-dimensional region that minimizes the average L_p distance between all pairs of points if the area of this region is held fixed? [The L_p distance between ... More
Dipolar-coupled moment correlations in clusters of magnetic nanoparticlesMar 05 2018Oct 30 2018Here, we investigate the nature of the moment coupling between 10-nm DMSA-coated magnetic nanoparticles, in both colloidal dispersion and in powder form. The individual iron oxide cores were composed of > 95% maghemite and agglomerated to clusters. At ... More
Crepant resolutions and brane tilings II: Tilting bundlesSep 10 2009Given a brane tiling, that is, a bipartite graph on a torus, we can associate with it a singular 3-Calabi-Yau variety. Using the brane tiling, we can also construct all crepant resolutions of the above variety. We give an explicit toric description of ... More
Evaluation of overlaps between arbitrary Fermionic quasiparticle vacuaSep 09 2011We derive an expression that allows for the unambiguous evaluation of the overlap between two arbitrary quasiparticle vacua, including its sign. Our expression is based on the Pfaffian of a skew-symmetric matrix, extending the formula recently proposed ... More
Interpolation between Airy and Poisson statistics for unitary chiral non-Hermitian random matrix ensemblesMar 22 2010We consider a family of chiral non-Hermitian Gaussian random matrices in the unitarily invariant symmetry class. The eigenvalue distribution in this model is expressed in terms of Laguerre polynomials in the complex plane. These are orthogonal with respect ... More
A general non-existence result for linear BSDEs driven by Gaussian processesSep 08 2015Jan 19 2016In this paper, we study linear backward stochastic differential equations driven by a class of centered Gaussian non-martingales, including fractional Brownian motion with Hurst parameter $H\in (0,1)\setminus \{\frac12\}$. We show that, for every choice ... More
Measurable cardinals and good $Σ_1(κ)$-wellorderingsApr 03 2017We study the influence of the existence of large cardinals on the existence of wellorderings of power sets of infinite cardinals $\kappa$ with the property that the collection of all initial segments of the wellordering is definable by a $\Sigma_1$-formula ... More
A novel processing pipeline for optical multi-touch surfacesJan 08 2013In this thesis a new approach for touch detection on optical multi-touch devices is proposed that exploits the fact that the camera images reveal not only the actual touch points but also objects above the screen such as the hand or arm of a user. The ... More
Measurement of VZ production cross sections in Z -> bb decay channels in pp collisions at 8 TeVAug 21 2014We present a measurement of the WZ and ZZ production cross sections in proton-proton collisions at 8 TeV in final states where one Z boson decays to b-tagged jets, while the other gauge boson, either W or Z, is detected through its leptonic decay. The ... More
Dynamic criticality far-from-equilibrium: one-loop flow of Burgers-Kardar-Parisi-Zhang systems with broken Galilean invarianceAug 06 2014Mar 22 2015Burgers-Kardar-Parisi-Zhang (KPZ) scaling has recently (re-) surfaced in a variety of physical contexts, ranging from anharmonic chains to quantum systems such as open superfluids, in which a variety of random forces may be encountered and/or engineered. ... More
An extension of cosmological dynamics with York timeJul 15 2014Feb 12 2015It has been suggested that the York parameter $T$ (effectively the scalar extrinsic curvature of a spatial hypersurface) may play the role of a fundamental time parameter. In a flat, forever expanding cosmology the York parameter remains always negative, ... More
An evaluation of Bradfordizing effectsDec 01 2008The purpose of this paper is to apply and evaluate the bibliometric method Bradfordizing for information retrieval (IR) experiments. Bradfordizing is used for generating core document sets for subject-specific questions and to reorder result sets from ... More
Optimal Reinforcement Learning for Gaussian SystemsJun 04 2011Oct 14 2011The exploration-exploitation trade-off is among the central challenges of reinforcement learning. The optimal Bayesian solution is intractable in general. This paper studies to what extent analytic statements about optimal learning are possible if all ... More
Quantum Computing in the de Broglie-Bohm Pilot-Wave PictureDec 21 2010Much attention has been drawn to quantum computing and the exponential speed-up in computation the technology would be able to provide. Various claims have been made about what aspect of quantum mechanics causes this speed-up. Formulations of quantum ... More
Three-Loop Calculation of the Higgs Boson Mass in SupersymmetryNov 30 2011A Key feature of the minimal supersymmetric extension of the Standard Model (MSSM) is the existence of a light Higgs boson, the mass of which is not a free parameter but an observable that can be predicted from the theory. Given that the LHC is able to ... More
Three-Loop Predictions for the Light Higgs Mass in the MSSMAug 02 2010The Minimal Supersymmetric Extension of the Standard Model (MSSM) features a light Higgs boson, the mass Mh of which is predicted by the theory. Given that the LHC will be able to measure the mass of a light Higgs with great accuracy, a precise theoretical ... More
AU Scale Structures in Extra-planar GasSep 15 2004Recent spectroscopic observations of intermediate- and high-velocity clouds (IVCs and HVCs) in the Milky Way halo have unveiled the presence of diffuse interstellar molecular hydrogen (H_2) several kpc away from the Galactic disk. Most of this H_2 gas ... More
An approach to Griffiths conjectureOct 27 2017The Griffiths conjecture asserts that every ample vector bundle $E$ over a compact complex manifold $S$ admits a hermitian metric with positive curvature in the sense of Griffiths. In this article we give a sufficient condition for a positive hermitian ... More
Neural Machine TranslationSep 22 2017Draft of textbook chapter on neural machine translation. a comprehensive treatment of the topic, ranging from introduction to neural networks, computation graphs, description of the currently dominant attentional sequence-to-sequence model, recent refinements, ... More
Living Labs - An Ethical Challenge for Researchers and Platform ProvidersJun 22 2017The infamous Facebook emotion contagion experiment is one of the most prominent and best-known online experiments based on the concept of what we here call "living labs". In these kinds of experiments, real-world applications such as social web platforms ... More
Binary Evolution and the Progenitor of SN 1987AFeb 13 2017Since the majority of massive stars are members of binary systems, an understanding of the intricacies of binary interactions is essential for understanding the large variety of supernova types and sub-types. I therefore briefly review the basic elements ... More
Vector boson fusion and scattering results from CMSOct 27 2017Measurements on vector boson scattering in the same-sign WW and fully leptonic ZZ channel, and a measurement of vector boson fusion of a Z boson are summarized. The three measurements are based on a dataset of proton--proton collisions at $\sqrt{s}=13\,\mathrm{Te\hspace{-.08em}V}$ ... More
Detecting cities in aerial night-time images by learning structural invariants using single reference augmentationOct 19 2018This paper examines, if it is possible to learn structural invariants of city images by using only a single reference picture when producing transformations along the variants in the dataset. Previous work explored the problem of learning from only a ... More
Semigroup Splitting And Cubature Approximations For The Stochastic Navier-Stokes EquationsMay 12 2011Approximation of the marginal distribution of the solution of the stochastic Navier-Stokes equations on the two-dimensional torus by high order numerical methods is considered. The corresponding rates of convergence are obtained for a splitting scheme ... More
Defining the set of integers in expansions of the real field by a closed discrete setJun 26 2009Oct 22 2009Let D\subseteq \mathbb{R} be closed and discrete and f:D^n \to \mathbb{R} be such that f(D^n) is somewhere dense. We show that (\mathbb{R},+,\cdot,f) defines the set of integers. As an application, we get that for every a,b \in \mathbb{R} with \log_{a}(b)\notin ... More
An analogue of the Baire Category TheoremJan 06 2011May 23 2012Every definably complete expansion of an ordered field satisfies an analogue of the Baire Category Theorem.
Indefinite Sturm-Liouville operators with periodic coefficientsApr 12 2011Apr 27 2012We investigate the spectral properties of the maximal operator $A$ associated with a differential expression $\frac 1 w(-\frac d {dx}(p\frac d {dx}) + q)$ with real-valued periodic coefficients $w$, $p$ and $q$ where $w$ changes sign. It turns out that ... More
Sobolev metrics on shape space of surfacesNov 15 2012Many procedures in science, engineering and medicine produce data in the form of geometric shapes. Mathematically, a shape can be modeled as an un-parameterized immersed sub-manifold, which is the notion of shape used here. Endowing shape space with a ... More
Termination criteria for inexact fixed point methodsSep 30 2013Mar 11 2014We analyze inexact fixed point iterations where the generating function contains an inexact solve of an equation system to answer the question of how tolerances for the inner solves influence the iteration error of the outer fixed point iteration. Important ... More
The Mg-sigma Relation of Elliptical Galaxies at Various RedshiftsJan 15 1997The correlation between the Mg absorption index and the velocity dispersion (sigma) of local elliptical galaxies is very tight. Because the Mg absorption depends on both metallicity and age of the underlying stellar population the observed Mg-sigma relation ... More
Twofold Transition in PT-Symmetric Coupled OscillatorsMay 30 2013The inspiration for this theoretical paper comes from recent experiments on a PT-symmetric system of two coupled optical whispering galleries (optical resonators). The optical system can be modeled as a pair of coupled linear oscillators, one with gain ... More
Asymptotic Analysis of the Boltzmann Equation for Dark Matter RelicsMar 08 2012This paper presents an asymptotic analysis of the Boltzmann equations (Riccati differential equations) that describe the physics of thermal dark-matter-relic abundances. Two different asymptotic techniques are used, boundary-layer theory, which makes ... More
Double-Scaling Limit of the O(N)-Symmetric Anharmonic OscillatorJul 16 2013In an earlier paper it was argued that the conventional double-scaling limit of an O(N)-symmetric quartic quantum field theory is inconsistent because the critical coupling constant is negative and thus the integral representing the partition function ... More
Nonuniqueness of the C operator in PT-symmetric quantum mechanicsFeb 28 2013The C operator in PT-symmetric quantum mechanics satisfies a system of three simultaneous algebraic operator equations, $C^2=1$, $[C,PT]=0$, and $[C,H]=0$. These equations are difficult to solve exactly, so perturbative methods have been used in the past ... More
Thermally-driven spin torques in layered magnetic insulatorsNov 12 2015Thermally-driven spin-transfer torques have recently been reported in electrically insulating ferromagnet$|$normal-metal heterostructures. In this paper, we propose two physically distinct mechanisms for such torques. The first is a local effect: out-of-equilibrium, ... More
Ristretto: Hardware-Oriented Approximation of Convolutional Neural NetworksMay 20 2016Convolutional neural networks (CNN) have achieved major breakthroughs in recent years. Their performance in computer vision have matched and in some areas even surpassed human capabilities. Deep neural networks can capture complex non-linear features; ... More
Axiomatic Description of Lefschetz Type Equivariant Homotopy InvariantsJan 30 2013We describe generators of universal Lefschetz groups consisting of self-maps of equivariant 1-spheres. This allows to formulate a normalization axiom which, together with the usual axioms, determines an equivariant Lefschetz number uniquely. We apply ... More
Are topic-specific search term, journal name and author name recommendations relevant for researchers?Aug 19 2014Aug 31 2014In this paper we describe a case study where researchers in the social sciences (n=19) assess topical relevance for controlled search terms, journal names and author names which have been compiled automatically by bibliometric-enhanced information retrieval ... More
Proceedings of the Data For Good Exchange 2016Sep 30 2016Oct 10 2016These are the proceedings of the Data For Good Exchange 2016, which was held in New York, NY, on September 26th 2016.
Molecular Gas in the Galactic Halo and BeyondSep 12 2001I review recent observations of molecular gas in the halo of the Milky Way and in the Magellanic Clouds. Far-ultraviolet absorption line studies of molecular hydrogen (H_2) with ORFEUS and FUSE have unveiled the presence of a diffuse molecular hydrogen ... More
ORFEUS II echelle spectra : H_2 measurements in the Magellanic CloudsMay 12 2000More than 20 years after the Copernicus satellite, ORFEUS allows the investigation of molecular hydrogen (H_2) in the diffuse interstellar medium by way of FUV absorption spectroscopy once again. This time, targets in the Magellanic Clouds were also observed, ... More
Cosmological perturbation theory with York timeNov 10 2015One method to overcome the notorious problem of time in the quantisation of gravity is the identification of a physically preferred time parameter, a promising candidate being so-called `York time'. The dynamical equations for matter and spatial geometry ... More
Fourier-Splitting methods for the dynamics of rotating Bose-Einstein condensatesNov 11 2014May 08 2015We present a new method to propagate rotating Bose-Einstein condensates subject to explicitly time-dependent trapping potentials. Using algebraic techniques, we combine Magnus expansions and splitting methods to yield any order methods for the multivariate ... More
Negotiation GamesSep 24 2015Negotiations, a model of concurrency with multi party negotiation as primitive, have been recently introduced by J. Desel and J. Esparza. We initiate the study of games for this model. We study coalition problems: can a given coalition of agents force ... More
Updated estimate of the number of edges in induced subgraphs of a special distance graphFeb 06 2018In this article, the author proposes a new approach for the estimating of the number of edges in induced subgraphs of a special distance graph. Author significantly improves previous estimates and suggests a new approach to obtaining better ones.
Constructing smooth and fully faithful tropicalizations for Mumford curvesMay 29 2018The tropicalization of an algebraic variety X is a combinatorial shadow of X, which is sensitive to a closed embedding of X into a toric variety. Given a good embedding, the tropicalization can provide a lot of information about X. We construct two types ... More
Locally definite normal operators in Krein spacesJun 14 2011Jul 29 2011We introduce the spectral points of two-sided positive type of bounded normal operators in Krein spaces. It is shown that a normal operator has a local spectral function on sets which are of two-sided positive type. In addition, we prove that the Riesz-Dunford ... More
Eigenvalues in gaps of selfadjoint operators in Pontryagin spacesNov 13 2011Given an open real interval \Delta\ and two selfadjoint operators A_1, A_2 in a \Pi_\kappa-space with n-dimensional resolvent difference we show that the difference of the total multiplicities of the eigenvalues of A_1 and A_2 in \Delta\ is at most n+2\kappa. ... More
A characterization of arithmetical invariants by the monoid of relations II: The monotone catenary degree and applications to semigroup ringsApr 02 2011The investigation and classification of non-unique factorization phenomena has attracted some interest in recent literature. For finitely generated monoids, S.T. Chapman and P.A. Garc\'ia-S\'anchez, together with several co-authors, derived a method to ... More
A characterization of arithmetical invariants by the monoid of relationsFeb 22 2010Mar 03 2010The investigation and classification of non-unique factorization phenomena have attracted some interest in recent literature. For finitely generated monoids, S.T. Chapman and P. Garcia-Sanchez, together with several co-authors, derived a method to calculate ... More
Expansions of the ordered additive group of real numbers by two discrete subgroupsJul 25 2014May 26 2015The theory of $(\mathbb{R},<,+,\mathbb{Z},\mathbb{Z} a)$ is decidable if $a$ is quadratic. If $a$ is the golden ratio, $(\mathbb{R},<,+,\mathbb{Z},\mathbb{Z} a)$ defines multiplication by $a$. The results are established by using the Ostrowski numeration ... More
The Tate-Voloch Conjecture in a Power of a Modular CurveOct 11 2012Jan 29 2013Let $p$ be a prime. Tate and Voloch proved that a point of finite order in the algebraic torus cannot be $p$-adically too close to a fixed subvariety without lying on it. The current work is motivated by the analogy between torsion points on semi-abelian ... More
Torsion Points on Elliptic Curves in Weierstrass FormMay 23 2011We prove that there are only finitely many complex numbers $a$ and $b$ with $4a^3+27b^2\not=0$ such that the three points $(1,*),(2,*),$ and $(3,*)$ are simultaneously torsion on the elliptic curve defined in Weierstrass form by $y^2=x^3+ax+b$. This gives ... More
A quantum cluster algebra of Kronecker type and the dual canonical basisFeb 14 2010Feb 19 2010The article concerns the dual of Lusztig's canonical basis of a subalgebra of the positive part U_q(n) of the universal enveloping algebra of a Kac-Moody Lie algebra of type A_1^{(1)}. The examined subalgebra is associated with a terminal module M over ... More
Quantum disorder in the spatially completely anisotropic triangular lattice I: Heisenberg $S=1/2$ antiferromagnetMay 09 2012Jan 29 2013Spin liquids occuring in 2D frustrated spin systems were initially assumed to appear at strongest frustration, but evidence grows that they more likely intervene at transitions between two different types of order. To identify if this is more general, ... More
Quantum computation from a de Broglie-Bohm perspectiveMay 11 2012We consider an example of a quantum algorithm from the point of view of the de Broglie-Bohm formulation of quantum mechanics. For concreteness we look at two particular implementations: one using spin-1/2 particles as described by a simple model due to ... More
Proceedings of the Data For Good Exchange 2016Sep 30 2016Oct 28 2016These are the proceedings of the Data For Good Exchange 2016, which was held in New York, NY, on September 26th 2016.
Three-loop corrections to the mass of the light Higgs boson in the MSSMJul 30 2010The Minimal Supersymmetric extension of the Standard Model (MSSM) predicts the existence of a light neutral Higgs boson. Once found at the LHC, its mass will immediately become a precision observable. The theoretical value of the Higgs mass Mh is subject ... More
Absorption Line Studies in the HaloSep 25 2003Significant progress has been made over the last few years to explore the gaseous halo of the Milky Way by way of absorption spectroscopy. I review recent results on absorption line studies in the halo using various instruments, such as the Far Ultraviolet ... More
On the Evolution and Appearance of a Surviving Companion after a Type Ia Supernova ExplosionMar 31 2003One promising method to test progenitor models for Type Ia supernovae is to identify surviving companion stars in historical supernova remnants. A surviving companion will have been strongly affected by its interaction with the supernova ejecta. Here ... More
Inclusive Jets in PHPOct 23 2013Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, ... More
Gravitation and cosmology with York timeSep 13 2016[Shortened abstract:] In this thesis we investigate a solution to the `problem of time' in canonical quantum gravity by splitting spacetime into surfaces of constant mean curvature parameterised by York time. We argue that there are reasons to consider ... More
Notes on socio-economic transparency mechanismsJun 15 2016Clearly, socio-economic freedom requires some extent of transparency regarding the implications of choices. In this paper, we review some established mechanisms for achieving such transparency, without any claim to completeness, and briefly discuss potential ... More
Analysis of aggregated tick returns: evidence for anomalous diffusionJun 18 2006Jun 20 2006In order to investigate the origin of large price fluctuations, we analyze stock price changes of ten frequently traded NASDAQ stocks in the year 2002. Though the influence of the trading frequency on the aggregate return in a certain time interval is ... More
Relevance distributions across Bradford Zones: Can Bradfordizing improve search?May 02 2013The purpose of this paper is to describe the evaluation of the effectiveness of the bibliometric technique Bradfordizing in an information retrieval (IR) scenario. Bradfordizing is used to re-rank topical document sets from conventional abstracting & ... More
When is scalar multiplication decidable?May 29 2015Mar 21 2019Let $K$ be a subfield of $\mathbb{R}$. The theory of $\mathbb{R}$ viewed as an ordered $K$-vector space and expanded by a predicate for $\mathbb{Z}$ is decidable if and only if $K$ is a real quadratic field.
Partition properties for simply definable colouringsJul 02 2018We study partition properties for uncountable regular cardinals that arise by restricting partition properties defining large cardinal notions to classes of simply definable colourings. We show that both large cardinal assumptions and forcing axioms imply ... More
Continuous Shearlet Tight FramesJan 10 2010Based on the shearlet transform we present a general construction of continuous tight frames for $L^2(\mathbb{R}^2)$ from any sufficiently smooth function with anisotropic moments. This includes for example compactly supported systems, piecewise polynomial ... More
Quantum cluster algebras of type A and the dual canonical basisJan 03 2011May 23 2013The article concerns the subalgebra U_v^+(w) of the quantized universal enveloping algebra of the complex Lie algebra sl_{n+1} associated with a particular Weyl group element of length 2n. We verify that U_v^+(w) can be endowed with the structure of a ... More
Quantum disorder in the spatially completely anisotropic triangular lattice II: frustrated hard-core bosonsMay 09 2012Jan 29 2013Spin liquids occuring in 2D frustrated spin systems were initially assumed to appear at strongest frustration, but evidence grows that they more likely intervene at transitions between two different types of order. To identify if this is more general, ... More
Bessel sequences from iterated operator actionsMay 24 2016May 30 2016Given a bounded normal operator $A$ in a Hilbert space and a fixed vector $x$, we elaborate on the problem of finding necessary and sufficient conditions under which $(A^kx)_{k\in\mathbb N}$ constitutes a Bessel sequence. We provide a characterization ... More
Renormalization group theory for fermions and order parameter fluctuations in interacting Fermi systemsSep 08 2011In this thesis, we perform a comprehensive renormalization group analysis of two- and three-dimensional Fermi systems at low and zero temperature. We examine systems with spontaneous symmetry-breaking and quantum critical behavior by deriving and solving ... More
Expectation Propagation on the Maximum of Correlated Normal VariablesOct 01 2009Many inference problems involving questions of optimality ask for the maximum or the minimum of a finite set of unknown quantities. This technical report derives the first two posterior moments of the maximum of two correlated Gaussian variables and the ... More
High-Velocity Clouds and the Local Intergalactic MediumFeb 15 2006In this article I review recent observations of the gaseous halos of galaxies and the intergalactic medium at low redshift. In the first part I discuss distribution, metal content, and physical properties of the Galactic intermediate- and high-velocity ... More
Tensor generators on schemes and stacksJun 23 2013Jul 19 2015We show that an algebraic stack with affine stabilizer groups satisfies the resolution property if and only if it is a quotient of a quasi-affine scheme by the action of the general linear group, or equivalently, if there exists a vector bundle whose ... More
Quantum mechanics as the dynamical geometry of trajectoriesJul 31 2015We illustrate how non-relativistic quantum mechanics may be recovered from a dynamical Weyl geometry on configuration space and an `ensemble' of trajectories (or `worlds'). The theory, which is free of a physical wavefunction, is presented starting from ... More
Quantum mechanics on York slicesJul 06 2015Jul 13 2015For some time the York time parameter has been identified as a candidate for a physically meaningful time in cosmology. An associated Hamiltonian may be found by solving the Hamiltonian constraint for the momentum conjugate to the York time variable, ... More
Nielsen-Schreier implies the finite Axiom of ChoiceJun 10 2015Oct 12 2015We present a new proof that the statement 'every subgroup of a free group is free' implies the Axiom of Choice for finite sets.
D^{+}, D^{0} and Lambda_{c}^{+} production in deep inelastic scattering at HERADec 06 2010Several recent measurements of charmed hadron production in deep inelastic scattering at HERA are reviewed. Cross sections for the production of D mesons were measured and compared to NLO QCD predictions. The charm contribution to the inclusive structure ... More
Curvature of higher direct imagesNov 28 2016Given a holomorphic family $f:\mathcal{X} \to S$ of compact complex manifolds of dimension $n$ and a relatively ample line bundle $L\to \mathcal{X}$, the higher direct images $R^{n-p}f_*\Omega^p_{\mathcal{X}/S}(L)$ carry a natural hermitian metric. We ... More
Bessel orbits of normal operatorsMay 24 2016Nov 01 2016Given a bounded normal operator $A$ in a Hilbert space and a fixed vector $x$, we elaborate on the problem of finding necessary and sufficient conditions under which $(A^kx)_{k\in\mathbb N}$ constitutes a Bessel sequence. We provide a characterization ... More
Malliavin Calculus and Density for Singular Stochastic Partial Differential EquationsSep 10 2018We study Malliavin differentiability of solutions to sub-critical singular parabolic stochastic partial differential equations (SPDEs) and we prove the existence of densities for a class of singular SPDEs. Both of these results are implemented in the ... More
Singular Moduli that are Algebraic UnitsFeb 07 2014We prove that only finitely many $j$-invariants of elliptic curves with complex multiplication are algebraic units. A rephrased and generalized version of this result resembles Siegel's Theorem on integral points of algebraic curves.
On the approximate periodicity of sequences attached to noncrystallographic root systemsJul 14 2016We study Fomin-Zelevinsky's mutation rule in the context of noncrystallographic root systems. In particular, we construct approximately periodic sequences of real numbers for the noncrystallographic root systems of rank 2 by adjusting the exchange relation ... More
Diophantine equations via cluster transformationsFeb 02 2016Motivated by Fomin and Zelevinsky's theory of cluster algebras we introduce a variant of the Markov equation; we show that all natural solutions of the equation arise from an initial solution by cluster transformations.
The fully-implicit log-conformation formulation and its application to three-dimensional flowsMar 12 2015Jul 30 2015The stable and efficient numerical simulation of viscoelastic flows has been a constant struggle due to the High Weissenberg Number Problem. While the stability for macroscopic descriptions could be greatly enhanced by the log-conformation method as proposed ... More
Globally structured 3D Analysis-suitable T-splines: definition, linear independence and m-graded local refinementMay 20 2015May 11 2016This paper addresses the linear independence of T-splines that correspond to refinements of three-dimensional tensor-product meshes. We give an abstract definition of analysis-suitability, and prove that it is equivalent to dual-compatibility, wich guarantees ... More
Strong convergence rates for Markovian representations of fractional Brownian motionFeb 04 2019Feb 15 2019Fractional Brownian motion can be represented as an integral over a family of Ornstein-Uhlenbeck processes. This representation naturally lends itself to numerical discretizations, which are shown in this paper to have strong convergence rates of arbitrarily ... More
Using the singular value decomposition to extract 2D correlation functions from scattering patternsMar 26 2019We apply the truncated singular value decomposition (SVD) to extract the underlying 2D correlation functions from small-angle scattering patterns. We test the approach by transforming the simulated data of ellipsoidal particles and show that also in case ... More
Cold gas accretion by high-velocity clouds and their connection to QSO absorption-line systemsNov 07 2011Mar 13 2012We combine HI 21cm observations of the Milky Way, M31, and the local galaxy population with QSO absorption-line measurements to geometrically model the three-dimensional distribution of infalling neutral gas clouds (HVCs) in the extended halos of low-redshift ... More
Dimensional Reduction Applied to Non-Supersymmetric TheoriesOct 12 2007We consider regularisation of a Yang-Mills theory by Dimensional Reduction (DRED). In particular, the anomalous dimensions of fermion masses and gauge coupling are computed to four-loop order. We put special emphasis on the treatment of evanescent couplings ... More
F_2^bbbar measurement at ZEUSJul 05 2010Two recent measurements of beauty production in deep inelastic scattering based on data collected by the ZEUS detector are summarised. In the first one, the beauty fraction in the data was obtained from events with a muon and a jet. In the second one, ... More
Constructing experimental indicators for Open Access documentsOct 11 2006The ongoing paradigm change in the scholarly publication system ('science is turning to e-science') makes it necessary to construct alternative evaluation criteria/metrics which appropriately take into account the unique characteristics of electronic ... More
Proceedings of the Data For Good Exchange 2016Sep 30 2016Nov 16 2016These are the proceedings of the Data For Good Exchange 2016, which was held in New York, NY, on September 26th 2016.
Commutative rings with a totally disconnected and non-Hausdorff maximal spectrumJan 25 2017In 1969 H\"ochster proved that for every quasi-compact T1-space $X$ we can find a commutative ring $R$ such that $X$ is homeomorphic to the maximal spectrum $\mathrm{Specm}(R)$ of $R$. This result implies the existence of a commutative ring $R$ that admits ... More