Results for "Anja Schedel"

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Capacity and Price Competition in Markets with Congestion EffectsMay 14 2019We study oligopolistic competition in service markets where firms offer a service to customers. The service quality of a firm (from a customer's perspective) depends on the level of congestion and the charged price. A firm can set a price for the service ... More
Wild translation surfaces and infinite genusOct 06 2014Jan 18 2017The Gauss-Bonnet formula for classical translation surfaces relates the cone angle of the singularities (geometry) to the genus of the surface (topology). When considering more general translation surfaces, we observe so-called wild singularities for ... More
Wild translation surfaces and infinite genusOct 06 2014Aug 12 2019The Gauss-Bonnet formula for classical translation surfaces relates the cone angle of the singularities (geometry) to the genus of the surface (topology). When considering more general translation surfaces, we observe so-called wild singularities for ... More
When wild singularities of translation surfaces imply infinite genusOct 06 2014We consider translation surfaces for which the metric completion is not necessarily a compact surface. Certain conditions on the additional points in the metric completion and on the dynamics of the translation surface imply that the surface has infinite ... More
Boson stars with nonminimal couplingDec 17 2015Boson stars coupled to Einstein's general relativity possess some features similar to gravastars, such as the anisotropy in principal pressures and relatively large compactness ($\mu_{max} = 0.32$). However, no matter how large the self-interaction is, ... More
Special rank one groups are perfectNov 23 2011T. De Medts, Y. Segev and K. Tent [Special Moufang sets, their root groups and their \mu-maps, Proc. Lond. Math. Soc. (3) 96 (2008), 767-791] proved that the little projective group of a special Moufang set M(U,\tau) is perfect provided that U has size ... More
Brief Report on the Extended Linear Sigma ModelJan 17 2013We present a chiral effective model which exhibits all the known symmetry features of the QCD Lagrangian. The extended Linear Sigma Model (eLSM) includes (pseudo-)scalar and (axial-) vector mesons, glueballs, and baryons. It has proven to be a useful ... More
Explicit solutions to quadratic BSDEs and applications to utility maximization in multivariate affine stochastic volatility modelsJan 13 2012Over the past few years quadratic Backward Stochastic Differential Equations (BSDEs) have been a popular field of research. However there are only very few examples where explicit solutions for these equations are known. In this paper we consider a class ... More
Radiation Zeros as an Observable to test Physics beyond the Standard ModelJul 05 1999The vanishing of the cross section for particular points in phase space - radiation zeros - is examined for the process $ q \bar q \to W^+W^- \gamma$ at high energy. For photon energies that are not too large, the cross section does exhibit deep dips ... More
Analytical index and eta forms for Dirac operators with one-dimensional kernel over a hypersurfaceMar 06 2015Jul 26 2017We generalize the transgression formula for the eta form of Bismut, Cheeger and Berline, Getzler, Vergne for vertical Dirac operators on a fibre bundle with odd dimensional fibres where the Dirac operators have locally at most one eigenvalue of multiplicity ... More
Horowitz-Randol pairs of curves in q-differential metricsOct 01 2012Nov 05 2013The Euclidean cone metrics coming from q-differentials on a closed surface of genus g > 1 define an equivalence relation on homotopy classes of closed curves declaring two to be equivalent if they have the equal length in every such metric. We prove an ... More
Multi-Syllable Phonotactic ModellingFeb 22 2001This paper describes a novel approach to constructing phonotactic models. The underlying theoretical approach to phonological description is the multisyllable approach in which multiple syllable classes are defined that reflect phonotactically idiosyncratic ... More
$τ$ Vector Spectral Function from a Chirally Invariant Hadronic Model with Weak InteractionNov 28 2014The linear sigma model we present here describes the vacuum phenomenology of the $N_F=2$ scalar, pseudoscalar, vector and axial-vector mesons at energies $\simeq 1\text{ GeV}$. Together with a local $SU(2)_L\times U(1)_Y$ symmetry obtained from a local ... More
Special rank one groups with abelian unipotent subgroups are perfectAug 31 2011T. De Medts, Y. Segev and K. Tent [Special Moufang sets, their root groups and their \mu-maps, Proc. Lond. Math. Soc. (3) 96 (2008), 767-791] proved that the little projective group of a special Moufang set M(U,\tau) is perfect provided that U has size ... More
Spectral tail processes and max-stable approximations of multivariate regularly varying time seriesApr 20 2017Jan 26 2018A regularly varying time series as introduced in Basrak and Segers (2009) is a (multivariate) time series such that all finite dimensional distributions are multivariate regularly varying. The extremal behavior of such a process can then be described ... More
Antiscreening in perturbative quantum gravity and resolving the Newtonian singularitySep 21 2012Aug 30 2013We calculate the quantum corrections to the Newtonian potential induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the graviton vacuum polarization calculated in our previous work and solve the equation of ... More
Dark energy-like stars from nonminimally coupled scalar fieldDec 16 2012Aug 30 2013We show that even a rather minimal extension of the Einstein - Hilbert action by a nonminimal coupling of the scalar field to the Ricci curvature scalar results in configurations that resemble more the dark energy stars then the ordinary boson stars. ... More
Perturbation Theory of Schrödinger Operators in Infinitely Many Coupling ParametersJan 27 1999In this paper we study the behavior of Hamilton operators and their spectra which depend on infinitely many coupling parameters or, more generally, parameters taking values in some Banach space. One of the physical models which motivate this framework ... More
False-Name Manipulation in Weighted Voting Games is Hard for Probabilistic Polynomial TimeMar 07 2013False-name manipulation refers to the question of whether a player in a weighted voting game can increase her power by splitting into several players and distributing her weight among these false identities. Analogously to this splitting problem, the ... More
Testing Stability Properties in Graphical Hedonic GamesDec 21 2018In hedonic games, players form coalitions based on individual preferences over the group of players they belong to. Several concepts to describe the stability of coalition structures in a game have been proposed and analyzed. However, prior research focuses ... More
On the product of projectors and generalized inversesAug 13 2013We consider generalized inverses of linear operators on arbitrary vector spaces and study the question when their product in reverse order is again a generalized inverse. This problem is equivalent to the question when the product of two projectors is ... More
Discrete Time Term Structure Theory and Consistent Recalibration ModelsSep 05 2014We develop theory and applications of forward characteristic processes in discrete time following a seminal paper of Jan Kallsen and Paul Kr\"uhner. Particular emphasis is placed on the dynamics of volatility surfaces which can be easily formulated and ... More
Joint exceedances of random productsMay 13 2015May 12 2016We analyze the joint extremal behavior of $n$ random products of the form $\prod_{j=1}^m X_j^{a_{ij}}, 1 \leq i \leq n,$ for non-negative, independent regularly varying random variables $X_1, \ldots, X_m$ and general coefficients $a_{ij} \in \mathbb{R}$. ... More
$k$-means clustering of extremesApr 05 2019The $k$-means clustering algorithm and its variant, the spherical $k$-means clustering, are among the most important and popular methods in unsupervised learning and pattern detection. In this paper, we explore how the spherical $k$-means algorithm can ... More
Topological inflation with graceful exitAug 20 2015Apr 26 2016We investigate a class of models of topological inflation in which a super-Hubble-sized global monopole seeds inflation. These models are attractive since inflation starts from rather generic initial conditions, but their not so attractive feature is ... More
A novel black hole mimicker: a boson star and a global monopole nonminimally coupled to gravityAug 29 2013Feb 11 2014A field-theoretic model for a highly compact object that mimicks a black hole is found for the gravitationally interacting system of a boson star and a global monopole which are nonminimally coupled to gravity. According to the strength of the nonlinear ... More
Time transients in the quantum corrected Newtonian potential induced by a massless nonminimally coupled scalar fieldJan 26 2011Sep 08 2011We calculate the one loop graviton vacuum polarization induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the Schwinger-Keldysh formalism, which allows us to study time dependent phenomena. As an application ... More
Distributed model predictive control for continuous-time nonlinear systems based on suboptimal ADMMJun 29 2017The paper presents a distributed model predictive control (DMPC) scheme for continuous-time nonlinear systems based on the alternating direction method of multipliers (ADMM). A stopping criterion in the ADMM algorithm limits the iterations and therefore ... More
Managing counterparty credit risk via BSDEsAug 10 2016Aug 16 2016We discuss a general dynamic replication approach to counterparty credit risk modeling. This leads to a fundamental jump-process backward stochastic differential equation (BSDE) for the credit risk adjusted portfolio value. We then reduce the fundamental ... More
Grain Nucleation Experiments and Other Laboratory DataJan 17 2012Jan 19 2012In order to interpret observations influenced by dust and to perform detailed modeling of the observable characteristics of dust-producing or dust-containing objects, knowledge of the micro-physical properties of relevant dust species are needed. Laboratory ... More
The spatial $Λ$-coalescentNov 22 2005This paper extends the notion of the $\la$-coalescent of Pitman (1999) to the spatial setting. The partition elements of the spatial $\Lambda$-coalescent migrate in a (finite) geographical space and may only coalesce if located at the same site of the ... More
Composing and Factoring Generalized Green's Operators and Ordinary Boundary ProblemsOct 31 2013We consider solution operators of linear ordinary boundary problems with "too many" boundary conditions, which are not always solvable. These generalized Green's operators are a certain kind of generalized inverses of differential operators. We answer ... More
New results on pathwise uniqueness for the heat equation with colored noiseDec 18 2012We consider strong uniqueness and thus also existence of strong solutions for the stochastic heat equation with a multiplicative colored noise term. Here, the noise is white in time and colored in q dimensional space ($q \geq 1$) with a singular correlation ... More
On Lennard-Jones systems with finite range interactions and their asymptotic analysisJan 26 2015Mar 17 2016In this work we study a one-dimensional chain of atoms with Lennard-Jones type interactions of finite range. In the bulk scaling we provide an explicit expression for the $\Gamma$-limit of the discrete energy as an integral functional involving the convexification ... More
Conditional Extreme Value Models: Fallacies and PitfallsJun 09 2016Conditional extreme value models have been introduced by Heffernan and Resnick (2007) to describe the asymptotic behavior of a random vector as one specific component becomes extreme. Obviously, this class of models is related to classical multivariate ... More
Uniqueness of solutions for a mathematical model for magneto-viscoelastic flowsMar 22 2017We investigate uniqueness of weak solutions for a system of partial differential equations capturing behavior of magnetoelastic materials. This system couples the Navier-Stokes equations with evolutionary equations for the deformation gradient and for ... More
Global monopoles can change Universe's topologyNov 26 2014Mar 17 2016If the Universe undergoes a phase transition, at which global monopoles are created or destroyed, topology of its spatial sections can change. More specifically, by making use of Myers' theorem, we show that, after a transition in which global monopoles ... More
Learning in a Compiler for MINSAT AlgorithmsDec 16 2003This paper describes learning in a compiler for algorithms solving classes of the logic minimization problem MINSAT, where the underlying propositional formula is in conjunctive normal form (CNF) and where costs are associated with the True/False values ... More
Extended Recurrence Plot Analysis and its Application to ERP DataDec 20 2002We present new measures of complexity and their application to event related potential data. The new measures base on structures of recurrence plots and makes the identification of chaos-chaos transitions possible. The application of these measures to ... More
A Noncommutative Mikusinski CalculusSep 06 2012We set up a left ring of fractions over a certain ring of boundary problems for linear ordinary differential equations. The fraction ring acts naturally on a new module of generalized functions. The latter includes an isomorphic copy of the differential ... More
On a Gamma-convergence analysis of a quasicontinuum methodMay 23 2014Nov 11 2014We investigate a quasicontinuum method by means of analytical tools. More precisely, we compare a discrete-to-continuum analysis of an atomistic one-dimensional model problem with a corresponding quasicontinuum model. We consider next and next-to-nearest ... More
On the graph-density of random 0/1-polytopesJun 17 2003Let X_{d,n} be an n-element subset of {0,1}^d chosen uniformly at random, and denote by P_{d,n} := conv X_{d,n} its convex hull. Let D_{d,n} be the density of the graph of P_{d,n} (i.e., the number of one-dimensional faces of P_{d,n} divided by n(n-1)/2). ... More
Voter models with heterozygosity selectionJan 19 2007Jan 25 2008This paper studies variations of the usual voter model that favor types that are locally less common. Such models are dual to certain systems of branching annihilating random walks that are parity preserving. For both the voter models and their dual branching ... More
On the Allen-Cahn/Cahn-Hilliard system with a geometrically linear elastic energyFeb 23 2012Aug 31 2012We present an extension of the Allen-Cahn/Cahn-Hilliard system which incorporates a geometrically linear ansatz for the elastic energy of the precipitates. The model contains both the elastic Allen-Cahn system and the elastic Cahn-Hilliard system as special ... More
Planck scale operators, inflation and fine tuningNov 23 2016Ultraviolet completion of the standard model plus gravity at and beyond the Planck scale is a daunting problem to which no generally accepted solution exists. Principal obstacles include (a) lack of data at the Planck scale (b) nonrenormalizability of ... More
On Lennard-Jones systems with finite range interactions and their asymptotic analysisJan 26 2015Jun 08 2017The aim of this work is to provide further insight into the qualitative behavior of mechanical systems that are well described by Lennard-Jones type interactions on an atomistic scale. By means of $\Gamma$-convergence techniques, we study the continuum ... More
A stochastic volatility model with flexible extremal dependence structureOct 17 2013Mar 24 2016Stochastic volatility processes with heavy-tailed innovations are a well-known model for financial time series. In these models, the extremes of the log returns are mainly driven by the extremes of the i.i.d. innovation sequence which leads to a very ... More
On spatial coalescents with multiple mergers in two dimensionsSep 24 2012We consider the genealogy of a sample of individuals taken from a spatially structured population when the variance of the offspring distribution is relatively large. The space is structured into discrete sites of a graph G. If the population size at ... More
Notes on the Veech group of the Chamanara surfaceDec 20 2016These notes discuss an infinite translation surface, introduced by Chamanara. We review his proof that the Veech group is a non-elementary Fuchsian group of the second kind which is generated by two parabolic elements.
Nonlinear expectations of random setsMar 12 2019Sublinear functionals of random variables are known as sublinear expectations; they are convex homogeneous functionals on infinite-dimensional linear spaces. We extend this concept for set-valued functionals defined on measurable set-valued functions ... More
$k$-means clustering of extremesApr 05 2019May 25 2019The $k$-means clustering algorithm and its variant, the spherical $k$-means clustering, are among the most important and popular methods in unsupervised learning and pattern detection. In this paper, we explore how the spherical $k$-means algorithm can ... More
Dust from AGB starsFeb 22 2007Dust is formed in the expanding atmosphere during late stages of stellar evolution. Dust influences the dynamics and thermodynamics of the stellar atmosphere by its opacity. The dust opacity depends both on the optical properties of the grain material ... More
Cusp excursion in hyperbolic manifolds and singularity of harmonic measureApr 25 2019We generalize the notion of cusp excursion of geodesic rays by introducing for any $k \geq 1$ the $k^{th}$ excursion in the cusps of a hyperbolic $N$-manifold of finite volume. We show that on one hand, this excursion is at most linear for geodesics that ... More
Conditional Extreme Value Models: Fallacies and PitfallsJun 09 2016Feb 23 2017Conditional extreme value models have been introduced by Heffernan and Resnick (2007) to describe the asymptotic behavior of a random vector as one specific component becomes extreme. Obviously, this class of models is related to classical multivariate ... More
Markov tail chainsApr 29 2013Feb 03 2014The extremes of a univariate Markov chain with regulary varying stationary marginal distribution and asymptotically linear behavior are known to exhibit a multiplicative random walk structure called the tail chain. In this paper, we extend this fact to ... More
Pathwise duals of monotone and additive Markov processesOct 21 2015Feb 28 2016This paper develops a systematic treatment of monotonicity-based pathwise dualities for Markov processes taking values in partially ordered sets. We show that every Markov process that takes values in a finite partially ordered set and whose generator ... More
Non-laminate Microstructures in Monoclinic-I MartensiteJan 31 2012Jun 19 2012We study the symmetrised rank-one convex hull of monoclinic-I martensite (a twelve-variant material) in the context of geometrically-linear elasticity. We construct sets of T3s, which are (non-trivial) symmetrised rank-one convex hulls of three-tuples ... More
Radiation Zeros in W^+W^-γProduction at High-Energy CollidersMay 14 1999The vanishing of the cross section for particular points in phase space - radiation zeros - is examined for the process $ q \bar q \to W^+W^- \gamma$ at high energy. Unlike the process $q \bar q' \to W^\pm \gamma$, actual zeros only occur in the soft-photon ... More
Energy Spectrum of Leptons from $e^+e^- \to W^+W^-$ in the Presence of Strong W^+_LW^-_L InteractionJan 09 1997The energy spectrum of leptons, produced by the decay of one or both W's in the reaction $e^+e^- \to W^+W^-$, is a significant probe of the helicity structure of this process. We calculate the energy spectrum $d \sigma /d E$ of a single decay lepton, ... More
Marked length spectral rigidity for flat metricsApr 05 2015In this paper we prove that the space of flat metrics (nonpositively curved Euclidean cone metrics) on a closed, oriented surface is marked length spectrally rigid. In other words, two flat metrics assigning the same lengths to all closed curves differ ... More
Subcritical contact processes seen from a typical infected siteOct 21 2011May 29 2013What is the long-time behavior of the law of a contact process started with a single infected site, distributed according to counting measure on the lattice? This question is related to the configuration as seen from a typical infected site and gives ... More
On the dust abundance gradients in late-type galaxies: II. Analytical models as evidence for massive interstellar dust growth in SINGS galaxiesJan 16 2012We use simple analytical models of the build up of the dust component and compare these with radial dust distributions derived from observations of SINGS galaxies. The observations show that dust gradients are indeed typically steeper than the corresponding ... More
Pathwise duals of monotone and additive Markov processesOct 21 2015Oct 25 2016This paper develops a systematic treatment of monotonicity-based pathwise dualities for Markov processes taking values in partially ordered sets. We show that every Markov process that takes values in a finite partially ordered set and whose generator ... More
Tightness of voter model interfacesJun 29 2007Jul 11 2007Consider a long-range, one-dimensional voter model started with all zeroes on the negative integers and all ones on the positive integers. If the process obtained by identifying states that are translations of each other is positively recurrent, then ... More
Anomalous Quartic Couplings in $ν\barν γγ$ Production via WW-Fusion at LEP2Jul 05 1999Sep 28 1999The production of $\nu \bar{\nu} \gamma \gamma$ in high-energy $e^+e^-$ collisions offers a window on anomalous quartic gauge boson couplings. We investigate the effect of two possible anomalous couplings on the cross section for $\nu \bar{\nu} \gamma ... More
Anomalous Quartic Couplings in W^+W^-γ, Z^0Z^0γand Z^0γγProduction at Present and Future e^+e^- CollidersMar 10 1999May 14 1999The production of three electroweak gauge bosons in high-energy $e^+e^-$ collisions offers a window on anomalous quartic gauge boson couplings. We investigate the effect of three possible anomalous couplings on the cross sections for $W^+W^-\gamma$, $Z^0Z^0\gamma$ ... More
A particle system with cooperative branching and coalescenceNov 02 2013May 28 2015In this paper, we introduce a one-dimensional model of particles performing independent random walks, where only pairs of particles can produce offspring ("cooperative branching"), and particles that land on an occupied site merge with the particle present ... More
Computing unit-weighted scales as a proxy for principal components or as factor score estimatesSep 18 2016Unit-weighted sum scales are sometimes considered as a simple method to compute factor score estimates and they are sometimes also considered as a proxy for component scores in the context of principal components analysis. The consequences of computing ... More
Genesis and evolution of dust in galaxies in the early Universe I. Modeling dust evolution in starburst galaxiesNov 13 2010Mar 06 2011We have developed a numerical galactic chemical evolution model. The model is constructed such that the effect of a wide range of parameters can be investigated. It takes into account results from stellar evolution models, a differentiation between diverse ... More
Buckling instability of a thin-layer rectilinear Couette flowMar 10 2011We analyse the buckling stability of a thin, viscous sheet when subject to simple shear, providing conditions for the onset of the dominant out-of-plane modes using two models: (i) an asymptotic theory for the dynamics of a viscous plate and (ii) the ... More
A Characterization of Undirected Graphs Admitting Optimal Cost SharesApr 06 2017Oct 04 2017In a seminal paper, Chen, Roughgarden and Valiant studied cost sharing protocols for network design with the objective to implement a low-cost Steiner forest as a Nash equilibrium of an induced cost-sharing game. One of the most intriguing open problems ... More
On the importance of Internet eXchange Points for today's Internet ecosystemJul 19 2013Jul 27 2013Internet eXchange Points (IXPs) are generally considered to be the successors of the four Network Access Points that were mandated as part of the decommissioning of the NSFNET in 1994/95 to facilitate the transition from the NSFNET to the "public Internet" ... More
Semantic Visualization and Navigation in Textual CorpusFeb 08 2012This paper gives a survey of related work on the information visualization domain and study the real integration of the cartography paradigms in actual information search systems. Based on this study, we propose a semantic visualization and navigation ... More
Differentiability of quadratic BSDEs generated by continuous martingalesJul 06 2009Mar 07 2012In this paper we consider a class of BSDEs with drivers of quadratic growth, on a stochastic basis generated by continuous local martingales. We first derive the Markov property of a forward--backward system (FBSDE) if the generating martingale is a strong ... More
Cost Sharing Games for Energy-Efficient Multi-Hop Broadcast in Wireless NetworksMay 28 2018We study multi-hop broadcast in wireless networks with one source node and multiple receiving nodes. The message flow from the source to the receivers can be modeled as a tree-graph, called broadcast-tree. The problem of finding the minimum-power broadcast-tree ... More
Saturation Effects and the Concurrency Hypothesis: Insights from an Analytic ModelNov 15 2016Nov 01 2017Sexual partnerships that overlap in time (concurrent relationships) may play a significant role in the HIV epidemic, but the precise effect is unclear. We derive edge-based compartmental models of disease spread in idealized dynamic populations with and ... More
Preparative fractionation of a random copolymer (SAN) with respect to either chain length or chemical compositionApr 17 2003The possibilities to fractionate copolymers with respect to their chemical composition on a preparative scale by means of the establishment of liquid/liquid phase equilibria were studied for random copolymers of styrene and acrylonitrile (san). Experiments ... More
Morphisms Cohomology and Deformations of Hom-algebrasOct 20 2017The purpose of this paper is to study deformation theory of Hom-associative algebra morphisms and Hom-Lie algebra morphisms. We introduce a suitable cohomology and discuss Infinitesimal deformations, equivalent deformations and obstructions. Moreover, ... More
Rigidity of the saddle connection complexOct 01 2018Nov 19 2018For a half-translation surface (S,q), the associated saddle connection complex A(S,q) is the simplicial complex where vertices are the saddle connections on (S,q), with simplices spanned by sets of pairwise disjoint saddle connections. This complex can ... More
Rotational component spaces for infinite-type translation surfacesDec 01 2014May 06 2016Finite translation surfaces can be classified by the order of their singularities. When generalizing to infinite translation surfaces, however, the notion of order of a singularity is no longer well-defined and has to be replaced by new concepts. This ... More
Rationalizing polymer swelling and collapse under repulsive to highly attractive cosolvent conditionsNov 05 2012The collapse and swelling behavior of a generic homopolymer is studied using implicit-solvent, explicit-cosolvent Langevin dynamics computer simulations for varying interaction strengths. The systematic investigation reveals that polymer swelling is maximal ... More
Radial stability analysis of the continuous pressure gravastarApr 18 2011Sep 25 2012Radial stability of the continuous pressure gravastar is studied using the conventional Chandrasekhar method. The equation of state for the static gravastar solutions is derived and Einstein equations for small perturbations around the equilibrium are ... More
Evolutionary Deep Learning to Identify Galaxies in the Zone of AvoidanceMar 06 2019Mar 20 2019The Zone of Avoidance makes it difficult for astronomers to catalogue galaxies at low latitudes to our galactic plane due to high star densities and extinction. However, having a complete sky map of galaxies is important in a number of fields of research ... More
Online Event Integration with StoryPivotOct 25 2016Modern data integration systems need to process large amounts of data from a variety of data sources and with real-time integration constraints. They are not only employed in enterprises for managing internal data but are also used for a variety of web ... More
Electrically charged gravastar configurationsJul 13 2008Dec 02 2008The notion of a compact object immune to the horizon problem and comprising an anisotropic inhomogeneous fluid with a specific radial pressure behavior, i.e. the gravastar, is extended by introducing an electrically charged component. Einstein-Maxwell ... More
Genesis and evolution of dust in galaxies in the early Universe II. Rapid dust evolution in quasars at z > 6Jan 07 2011Mar 06 2011We assess the most plausible scenarios for generating large amounts of dust in high-z quasars (QSOs) on the basis of observationally derived physical properties of QSOs at z > 6. We use a chemical evolution model to compute the temporal progression of ... More
Rotational component spaces for infinite-type translation surfacesDec 01 2014Aug 09 2018Finite translation surfaces can be classified by the order of their singularities. When generalizing to infinite translation surfaces, however, the notion of order of a singularity is no longer well-defined and has to be replaced by new concepts. This ... More
Trait-dependent branching particle systems with competition and multiple offspringAug 28 2018Dec 20 2018In this work we model the dynamics of a population that evolves as a continuous time branching process with a trait structure and ecological interactions in form of mutations and competition between individuals. We generalize existing microscopic models ... More
Quantifying impacts of the drought 2018 on European ecosystems in comparison to 2003Jun 07 2019Jul 15 2019In recent decades, an increasing persistence of atmospheric circulation patterns has been observed. In the course of the associated long-lasting anticyclonic summer circulations, heat waves and drought spells often coincide, leading to so-called hotter ... More
The shape of a generic translation surfaceSep 27 2018Dec 20 2018A translation structure equips a Riemann surface with a singular flat metric. Not much is known about the shape of a generic translation surface. We consider the stratum H_1(2g-2) of translation surfaces of genus g with one singularity and show that the ... More
How important are metal-poor AGB stars as cosmic dust producers?May 18 2015The efficiency of dust formation in oxygen-rich AGB stars should (in theory) be metallicity dependent since they are not producing their own raw material for dust production. Metal-poor carbon stars may not be very efficient dust producers either, because ... More
Cryptographic protocols based on Nielsen transformationsApr 13 2015Based on a combinatorial distribution of shares we present in this paper secret sharing schemes and cryptosystems using Nielsen transformations.
Limit laws of the empirical Wasserstein distance: Gaussian distributionsJul 15 2015Feb 19 2016We derive central limit theorems for the Wasserstein distance between the empirical distributions of Gaussian samples. The cases are distinguished whether the underlying laws are the same or different. Results are based on the (quadratic) Frechet differentiability ... More
A note on locking materials and gradient polyconvexityJun 13 2017May 31 2018We use gradient Young measures generated by Lipschitz maps to define a relaxation of integral functionals which are allowed to attain the value $+\infty$ and can model ideal locking in elasticity as defined by Prager in 1957. Furthermore, we show the ... More
Modeling disease spread in populations with birth, death, and concurrencyNov 15 2016The existence of sexual partnerships that overlap in time (concurrent relationships) is believed by some to be a significant contributing factor to the spread of HIV, although this is controversial. We derive an analytic model which allows us to investigate ... More
Quantifying impacts of the drought 2018 on European ecosystems in comparison to 2003Jun 07 2019In recent decades, an increasing persistence of atmospheric circulation patterns has been observed. In the course of the associated long-lasting anticyclonic summer circulations, heat waves and drought spells often coincide, leading to so-called hotter ... More
Derivation of $\mathbf{F}=\mathbf{F}^e\mathbf{F}^p$ as the continuum limit of crystalline slipApr 25 2015In this paper we provide a proof of the multiplicative kinematic description of crystal elastoplasticity in the setting of large deformations, i.e. $\mathbf{F}=\mathbf{F}^e\mathbf{F}^p$, for a two dimensional single crystal. The proof starts by considering ... More
Extensibility of a system of transport equations in the case of an impermeable boundaryDec 07 2018We show that the steady and unsteady system of transport equations with a nonhomogeneous right hand side can be extended from its domain that possesses an impermeable $C^2$-boundary to the whole space.
Pilot-wave dynamics of two identical, in-phase bouncing dropletJun 27 2018A droplet bouncing on the surface of a vibrating liquid bath can move horizontally guided by the wave it produces on impacting the bath. The wave itself is modified by the environment, and thus the interactions of the moving droplet with the surroundings ... More
Radial pulsations and stability of anisotropic stars with quasi-local equation of stateOct 05 2010Jan 19 2011Quasi-local variables, i.e. quantities whose values can be derived from physics accessible within an arbitrarily small neighborhood of a spacetime point, are used to construct the equation of state (EoS) for the anisotropic fluid in the spherical symmetry. ... More