Results for "Christian Gleissner"

total 11004took 0.12s
The pluricanonical systems of a product-quotient varietyOct 02 2018We give a method for the computation of the plurigenera of a product-quotient manifold. We give two different types of applications to it: to the construction of Calabi-Yau threefolds and to the determination of the minimal model of a product-quotient ... More
Mixed Threefolds Isogenous to a ProductMar 07 2017In this paper we study \emph{threefolds isogenous to a product of mixed type} i.e. quotients of a product of three compact Riemann surfaces $C_i$ of genus at least two by the action of a finite group $G$, which is free, but not diagonal. In particular, ... More
On Threefolds Isogenous to a Product of CurvesDec 19 2014Jan 14 2015A threefold isogenous to a product of curves $X$ is a quotient of a product of three compact Riemann surfaces of genus at least $2$ by the free action of a finite group. In this paper we study these threefolds under the assumption that the group acts ... More
A family of threefolds of general type with canonical map of high degreeFeb 08 2019In this note we provide a two-dimensional family of smooth minimal threefolds of general type with canonical map of degree 96, improving the previous known bound of 72.
On Threefolds Isogenous to a Product of CurvesDec 19 2014Mar 08 2017A threefold isogenous to a product of curves $X$ is a quotient of a product of three compact Riemann surfaces of genus at least two by the free action of a finite group. In this paper we study these threefolds under the assumption that the group acts ... More
New surfaces with canonical map of high degreeJul 31 2018We give an algorithm that, for a given value of the geometric genus $p_g,$ computes all regular product-quotient surfaces with abelian group that have at most canonical singularities and have canonical system with at most isolated base points. We use ... More
Staggered domain wall fermionsSep 16 2016We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared ... More
Differential Characters and Geometric ChainsMar 26 2013Apr 09 2013We study Cheeger-Simons differential characters and provide geometric descriptions of the ring structure and of the fiber integration map. The uniqueness of differential cohomology (up to unique natural transformation) is proved by deriving an explicit ... More
Distances and large deviations in the spatial preferential attachment modelSep 26 2018Sep 27 2018We investigate two asymptotic properties of a spatial preferential-attachment model introduced by E. Jacob and P. M\"orters (2013). First, in a regime of strong linear reinforcement, we show that typical distances are at most of doubly-logarithmic order. ... More
Relaxed Logarithmic Barrier Function Based Model Predictive Control of Linear SystemsMar 11 2015In this paper, we investigate the use of relaxed logarithmic barrier functions in the context of linear model predictive control. We present results that allow to guarantee asymptotic stability of the corresponding closed-loop system, and discuss further ... More
A stabilizing iteration scheme for model predictive control based on relaxed barrier functionsMar 15 2016Apr 06 2016We propose and analyze a stabilizing iteration scheme for the algorithmic implementation of model predictive control for linear discrete-time systems. Polytopic input and state constraints are considered and handled by means of so-called relaxed logarithmic ... More
Friction force: from mechanics to thermodynamicsNov 17 2009Jul 01 2010We study some mechanical problems in which a friction force is acting on the system. Using the fundamental concepts of state, time evolution and energy conservation we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws ... More
On the relativistic KMS condition for the P(φ)_2 modelSep 29 2006The relativistic KMS condition introduced by Bros and Buchholz provides a link between quantum statistical mechanics and quantum field theory. We show that for the $P(\phi)_2$ model at positive temperature, the two point function for fields satisfies ... More
Spectral properties and chiral symmetry violations of (staggered) domain wall fermions in the Schwinger modelFeb 26 2016Jul 05 2016We follow up on a suggestion by Adams and construct explicit domain wall fermion operators with staggered kernels. We compare different domain wall formulations, namely the standard construction as well as Borici's modified and Chiu's optimal construction, ... More
Thermal Quantum Fields with Spatially Cut-off Interactions in 1+1 Space-time DimensionsJul 25 2003We construct interacting quantum fields in 1+1 space-time dimensions, representing charged or neutral scalar bosons at positive temperature and zero chemical potential. Our work is based on prior work by Klein and Landau and Hoegh-Krohn. Generalized path ... More
On spatial and temporal multilevel dynamics and scaling effects in epileptic seizuresMar 30 2011Jul 29 2011Epileptic seizures are one of the most well-known dysfunctions of the nervous system. During a seizure, a highly synchronized behavior of neural activity is observed that can cause symptoms ranging from mild sensual malfunctions to the complete loss of ... More
Duck Traps: Two-dimensional Critical Manifolds in Planar SystemsAug 30 2018Nov 05 2018In this work we consider two-dimensional critical manifolds in planar fast-slow systems near fold and so-called canard (=`duck') points. These higher-dimension, and lower-codimension, situation is directly motivated by the case of hysteresis operators ... More
Thermal Quantum Fields without Cut-offs in 1+1 Space-time DimensionsMar 26 2004We construct interacting quantum fields in 1+1 dimensional Minkowski space, representing neutral scalar bosons at positive temperature. Our work is based on prior work by Klein and Landau and Hoegh-Krohn
Uncertainty Transformation via Hopf Bifurcation in Fast-Slow SystemsDec 09 2015Propagation of uncertainty in dynamical systems is a significant challenge. Here we focus on random multiscale ordinary differential equation models. In particular, we study Hopf bifurcation in the fast subsystem for random initial conditions. We show ... More
A mathematical framework for critical transitions: normal forms, variance and applicationsJan 14 2011Oct 12 2012Critical transitions occur in a wide variety of applications including mathematical biology, climate change, human physiology and economics. Therefore it is highly desirable to find early-warning signs. We show that it is possible to classify critical ... More
Complex Eigenvalues for Binary Subdivision SchemesJan 21 2008Convergence properties of binary stationary subdivision schemes for curves have been analyzed using the techniques of z-transforms and eigenanalysis. Eigenanalysis provides a way to determine derivative continuity at specific points based on the eigenvalues ... More
A Symplectic Method to Generate Multivariate Normal DistributionsMay 16 2012The AMAS group at the Paul Scherrer Institute developed an object oriented library for high performance simulation of high intensity ion beam transport with space charge. Such particle-in-cell (PIC) simulations require a method to generate multivariate ... More
A Geometrical Method of DecouplingJan 04 2012Jul 16 2013The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries - like midplane symmetrie - are present, then it is possible to treat the betatron motion in the horizontal, the ... More
The GMc-interpretation of Quantum MechanicsFeb 25 2008The GMc-interpretation (Gravitation-Motion of mass-light with maximal speed c) is a consistent approach to quantum mechanics very closely related to classical physics. Several postulates are formulated that are satisfied in classical physics, general ... More
Planar Pixel Sensors for the ATLAS tracker upgrade at HL-LHCJun 15 2012The ATLAS Planar Pixel Sensor R&D Project is a collaboration of 17 institutes and more than 80 scientists. Their goal is to explore the operation of planar pixel sensors for the tracker upgrade at the High Luminosity-Large Hadron Collider (HL-LHC). This ... More
On a Formation Scenario of Star ClustersDec 04 2001Most formation scenarios of globular clusters assume a molecular cloud as the progenitor of the stellar system. However, it is still unclear, how this cloud is transformed into a star cluster, i.e. how the destructive processes related to gas removal ... More
Cryptography in the Bounded-Quantum-Storage ModelSep 03 2007This thesis initiates the study of cryptographic protocols in the bounded-quantum-storage model. On the practical side, simple protocols for Rabin Oblivious Transfer, 1-2 Oblivious Transfer and Bit Commitment are presented. No quantum memory is required ... More
Semileptonic B / Bs decays at BelleMay 16 2013The Belle experiment at the KEKB asymmetric energy e+e- collider recorded large data sets of both, B and Bs decays. Semileptonic decays B(s) -> X l nu (l = electron or muon) constitute approximately one fifth of the total decay width of B(s) mesons and ... More
Sur les quotients discrets de semi-groupes complexesApr 22 2008Let $X=G/K$ be an irreducible Hermitian symmetric space of the non-compact type and let $S\in G^\mbb{C}$ be the associated compression semi-group. Let $\Gamma$ be a discrete subgroup of $G$. We give a sufficient condition for $\Gamma\backslash S$ to be ... More
Potts-like model for ghetto formation in multi-cultural societiesSep 25 2004In a Potts-like model of $Q$ ethnic groups, we follow Schelling (1971) and Meyer-Ortmanns (2003) and simulate the formation of ethnic ghettos as well as their prevention by an increasing social temperature.
Long-range interactions in Sznajd consensus modelSep 14 2002The traditional Sznajd model, as well as its Ochrombel simplification, for opinion spreading are modified to have a convincing strength proportional to a negative power of the spatial distance. We find the usual phase transition in the full Sznajd model, ... More
Ideal Stars and General RelativityJun 06 2006We study a system of differential equations that governs the distribution of matter in the theory of General Relativity. The new element in this paper is the use of a dynamical action principle that includes all the degrees of freedom, matter as well ... More
Action Principle for Hydrodynamics and Thermodynamics including general, rotational flowsMay 28 2014Jan 12 2016The restriction of hydrodynamics to non-viscous, potential (gradient, irrotational) flows is a theory both simple and elegant; a favorite topic of introductory textbooks. It is known that this theory can be formulated as an action principle and expanded ... More
Growth of a Black HoleAug 11 2005This paper studies the interpretation of physics near a Schwarzschild black hole. A scenario for creation and growth is proposed that avoids the conundrum of information loss. In this picture the horizon recedes as it is approached and has no physical ... More
Retrospective on QuantizationMar 14 2001Quantization is still a central problem of modern physics. One example of an unsolved problem is the quantization of Nambu mechanics. After a brief comment on the role of Harrison cohomology, this review concentrates on the central problem of quantization ... More
Integrated Structure and Semantics for Reo Connectors and Petri NetsNov 29 2009In this paper, we present an integrated structural and behavioral model of Reo connectors and Petri nets, allowing a direct comparison of the two concurrency models. For this purpose, we introduce a notion of connectors which consist of a number of interconnected, ... More
Descending plane partitions and rhombus tilings of a hexagon with triangular holeOct 13 2003It is shown that the descending plane partitions of Andrews can be geometrically realized as cyclically symmetric rhombus tilings of a certain hexagon where an equilateral triangle of side length 2 has been removed from its centre. Thus, the lattice structure ... More
Falicov-Kimball Models: A Partial Review of the Ground States ProblemNov 20 1998In this review we present a biased review of the ground state properties of the Falicov-Kimball models in 1,2 and infinite dimensions, considering either fermions or hard-core bosons. In particular we want to show the very rich structure that these models ... More
Exact relativistic treatment of stationary counter-rotating dust disks II: Axis, Disk and Limiting CasesFeb 19 2001This is the second in a series of papers on the construction of explicit solutions to the stationary axisymmetric Einstein equations which can be interpreted as counter-rotating disks of dust. We discuss the class of solutions to the Einstein equations ... More
Synchronous Subsequentiality and Approximations to Undecidable ProblemsSep 24 2015We introduce the class of synchronous subsequential relations, a subclass of the synchronous relations which embodies some properties of subsequential relations. If we take relations of this class as forming the possible transitions of an infinite automaton, ... More
Kleene Algebras, Regular Languages and Substructural LogicsAug 26 2014We introduce the two substructural propositional logics KL, KL+, which use disjunction, fusion and a unary, (quasi-)exponential connective. For both we prove strong completeness with respect to the interpretation in Kleene algebras and a variant thereof. ... More
High Energy Neutrino Astronomy: Status and PerspectivesNov 28 2008The year 2008 has witnessed remarkable steps in developing high energy neutrino telescopes. IceCube at the South Pole has been deployed with 40 of its planned 80 strings and reached half a cubic kilometer instrumented volume, in the Mediterranean Sea ... More
Perspectives on Einstein's scientific works in MilanAug 20 2015The Milanese period in Albert Einstein's life is a key one for the understanding of the development of his scientific questioning. While being a student in Z\"urich from 1896, Einstein returned regularly to Milan to meet his family for the holidays. There, ... More
Clustering strategy and method selectionMar 06 2015This paper is a chapter in the forthcoming Handbook of Cluster Analysis, Hennig et al. (2015). For definitions of basic clustering methods and some further methodology, other chapters of the Handbook are referred to. To read this version of the paper ... More
Critical groups of group representationsJun 02 2016Jul 15 2016This paper investigates the critical group of a faithful representation of a finite group. It computes the order of the critical group in terms of the character values, and gives some restrictions on its subgroup structure. It also computes the precise ... More
A coalgebraic model of graphsAug 10 2015Jan 17 2016For a set-endofunctor $F$, a graph is triple $(V,E,g)$ with a structure map $g:E\rightarrow F V$. This model is a generalized coalgebra over the category of sets. In this note, we model graphs as coalgebras over $Set\times Set$ and use the theory of coalgebras ... More
Finding Preference Profiles of Condorcet Dimension $k$ via SATFeb 18 2014Mar 02 2016Condorcet winning sets are a set-valued generalization of the well-known concept of a Condorcet winner. As supersets of Condorcet winning sets are always Condorcet winning sets themselves, an interesting property of preference profiles is the size of ... More
On the second fluctuation--dissipation theorem for nonequilibrium bathsSep 12 2013Baths produce friction and random forcing on particles suspended in them. The relation between noise and friction in (generalized) Langevin equations is usually referred to as the second fluctuation-dissipation theorem. We show what is the proper nonequilibrium ... More
TiD -- Documentation of TOBI Interface DJul 06 2015This document contains the documentation of TOBI (Tools for BCI) Interface D (TiD). TiD tries to establish a standardized interface for event transmission in neuroscience experiments. It is designed in a client-server architecture. Clients are connecting ... More
Coalgebras and quantizationJun 23 2005Two coalgebra structures are used in quantum field theory. The first one is the coalgebra part of a Hopf algebra leading to deformation quantization. The second one is a co-module co-algebra over the first Hopf algebra and it is used to define connected ... More
A quantum field algebraJan 16 2002The Laplace Hopf algebra created by Rota and coll. is generalized to provide an algebraic tool for combinatorial problems of quantum field theory. This framework encompasses commutation relations, normal products, time-ordered products and renormalisation. ... More
Runge-Kutta methods and renormalizationApr 02 1999A connection between the algebra of rooted trees used in renormalization theory and Runge-Kutta methods is pointed out. Butcher's group and B-series are shown to provide a suitable framework for renormalizing a toy model of field the ory, following Kreimer's ... More
Schwinger Pair Creation of Particles and StringsMar 01 2011I shortly review the worldline instanton method for calculating Schwinger pair production rates in (i) one-loop QED (ii) multiloop QED and (iii) one-loop open string theory.
QED in the Worldline FormalismNov 27 2000A survey is given of applications of the ``string-inspired'' worldline formalism to the computation of amplitudes and effective actions in QED.
An Introduction to the Worldline Technique for Quantum Field Theory CalculationsOct 16 1996Aug 03 1997These two lectures give a pedagogical introduction to the ``string-inspired'' worldline technique for perturbative calculations in quantum field theory. This includes an overview over the present range of its applications. Several examples are calculated ... More
On the Splitting of the Dual Goldie Torsion TheorySep 10 1998Dec 07 1999The splitting of the Goldie (or singular) torsion theory has been extensively studied. Here we determine an appropriate dual Goldie torsion theory, discuss its splitting and answer in the negative a question proposed by Ozcan and Harmanci as to whether ... More
The Secondary Stars of Cataclysmic VariablesJan 07 2011May 04 2011I review what we know about the donor stars in cataclysmic variables (CVs), focusing particularly on the close link between these binary components and the overall secular evolution of CVs. I begin with a brief overview of the "standard model" of CV evolution ... More
The Donor Stars of Cataclysmic VariablesSep 25 2006Jul 04 2007We construct a complete, semi-empirical donor sequence for CVs with orbital periods less than 6 hrs. All key physical and photometric parameters of CV secondaries (along with their spectral types) are given as a function of P_orb along this sequence. ... More
Morphisms to Brauer-Severi varieties, with applications to del Pezzo surfacesFeb 24 2016We classify morphisms from proper varieties to Brauer-Severi varieties, which generalizes the classical correspondence between morphisms to projective space and globally generated invertible sheaves. As an application, we study del Pezzo surfaces of large ... More
The skew diagram poset and components of skew charactersMar 31 2011We investigate the poset of skew diagrams ordered by adding or forming the union of skew diagrams. We will show that a skew diagram which has at least n convex corners to the upper left and also to the lower right is larger than the skew diagram consisting ... More
A Q-Operator Identity for the Correlation Functions of the Infinite XXZ Spin-ChainMar 16 2005Jul 20 2005An explicit construction for Q-operators of the finite XXZ spin-chain with twisted boundary conditions is presented. The massless and the massive regime is considered as well as the root of unity case. It is explained how these results yield an alternative ... More
Representation Theory and Baxter's TQ equation for the six-vertex model. A pedagogical overviewNov 30 2004A summary of the construction procedure of generalized versions of Baxter's Q-operator is given. Illustrated by several figures and diagrams the use of representation theory is explained step-by-step avoiding technical details. The relation with the infinite-dimensional ... More
The twisted XXZ chain at roots of unity revisitedAug 14 2003Aug 22 2003The symmetries of the twisted XXZ spin-chain (alias the twisted six-vertex model) at roots of unity are investigated. It is shown that when the twist parameter is chosen to depend on the total spin an infinite-dimensional non-abelian symmetry algebra ... More
Auxiliary matrices for the six-vertex model at roots of unity IIMay 16 2003Jan 06 2004The spectra of recently constructed auxiliary matrices for the six-vertex model respectively the spin s=1/2 Heisenberg chain at roots of unity q^N=1 are investigated. Two conjectures are formulated both of which are proven for N=3 and are verified numerically ... More
Global spectral fluctuations in the Gaussian Unitary EnsembleOct 20 2015We consider global fluctuations of the spectrum of the GUE. Using results on the linear statistics of such matrices as well as variance bounds on the eigenvalues, we show that under a suitable scaling, global fluctuations of the spectrum can be asymptotically ... More
Linear statistics of the circular $β$-ensemble, Stein's method, and circular Dyson Brownian motionJul 30 2015Apr 25 2016We study the linear statistics of the circular $\beta$-ensemble with a Stein's method argument, where the exchangeable pair is generated through circular Dyson Brownian motion. This generalizes previous results obtained in such a way for the CUE and provides ... More
Unitarity constraints on top quark signatures of Higgsless modelsApr 26 2005Jun 10 2005We use conditions for unitarity cancellations to constrain the couplings of the top and bottom quarks to Kaluza-Klein modes in Higgsless models of electroweak symmetry breaking. An example for the mass spectrum of quark resonances in a theory space model ... More
Gauge checks, consistency of approximation schemes and numerical evaluation of realistic scattering amplitudesJul 04 2003Dec 17 2003We discuss both theoretical tools to verify gauge invariance in numerical calculations of cross sections and the consistency of approximation schemes used in realistic calculations. A finite set of Ward Identities for 4 point scattering amplitudes is ... More
Gamma-Ray Bursts, Collisionless Shocks and Synthetic SpectraJun 23 2005The radiation from afterglows of gamma-ray bursts (GRB) is generated in collisionless plasma shocks. The two main ingredients behind the radiation are high-energy, non-thermal electrons and a strong magnetic field. I argue that in order to make the right ... More
Introducing bisemistructuresJul 25 2006New fundamental mathematical structures are introduced by the triples (left semistructure,right semistructure,bisemistructure) associated with the classical mathematical structures and such that the bisemistructures,resulting from the reciprocal actions ... More
The Thurston's program derived from the Langlands global program with singularitiesDec 21 2006The seven non euclidean geometries of the Thurston's geometrization program are proved to originate naturally from singularization morphisms and versal deformations on euclidean 3-manifolds generated in the frame of the Langlands global program. The Poincare ... More
The Langlands functoriality conjecture in the bisemialgebra frameworkAug 28 2006The Langlands functoriality conjecture envisaged in the bisemialgebra framework is proved to correspond to the nonorthogonal completely reducible cuspidal representations of the bilinear algebraic semigroups.
Electron-positron pair production in inhomogeneous electromagnetic fieldsDec 18 2015The process of electron-positron pair production is investigated within the phase-space Wigner formalism. The similarities between atomic ionization and pair production for homogeneous, but time-dependent linearly polarized electric fields are examined ... More
An Introduction into the Theory of Cosmological Structure FormationAug 29 2012Feb 01 2013This text aims to give a pedagogical introduction into the main concepts of the theory of structure formation in the universe. The text is suited for graduate students of astronomy with a moderate background in general relativity. A special focus is laid ... More
Differential geometry and scalar gravitational wavesNov 05 2013Following some strong argumentations of differential geometry in the Landau's book, some corrections about errors in the old literature on scalar gravitational waves (SGWs) are given and discussed. In the analysis of the response ofi nterferometers the ... More
Dark Energy and Dark Matter like intrinsic curvature in extended gravity. Viability through gravitational wavesNov 06 2012Towards the goal to quantize gravity, in this short review we discuss an intermediate step which consists in extending the picture of standard General Relativity by considering Extended Theories of Gravity. In this tapestry, the equations to quantize ... More
Gravitational wave astronomy: the definitive test for the "Einstein frame versus Jordan frame" controversyOct 11 2010Dec 21 2010The potential realization of a gravitational wave (GW) astronomy in next years is a great challenge for the scientific community. By giving a significant amount of new information, GWs will be a cornerstone for a better understanding of the universe and ... More
Theoretical corrections on scalar gravitational wavesOct 31 2006Jan 08 2012Following some ideas in the Landau book, some corrections about errors in the old literature on scalar gravitational waves are given and discussed. Even if such errors can be considered not important from the point of view of observations, because they ... More
Non-strictly black body spectrum from the tunnelling mechanismMay 17 2013Jul 11 2014A modern and largely used approach to obtain Hawking radiation is the tunnelling mechanism. However, in various papers in the literature, the analysis concerned almost only to obtain the Hawking temperature through a comparison of the probability of emission ... More
Cosmology of Einstein-Vlasov system in a weak modification of general relativityJun 20 2011Aug 19 2011In earlier work it was shown that a weak modification of general relativity, in the linearized approach, renders a spherically symmetric and stationary model of the Universe. This was due to the presence of a third mode of polarization in the linearized ... More
On the longitudinal response function of interferometers for massive gravitational waves from a bimetric theory of gravityJul 31 2008Aug 26 2008Recently, some papers in the literature have shown that, from a bimetric theory of gravity, it is possible to produce massive gravitational waves which generate a longitudinal component in a particular polarization of the wave. After a review of previous ... More
A solution of linearized Einstein field equations in vacuum used for the detection of the stochastic background of gravitational wavesJun 20 2008A solution of linearized Einstein field equations in vacuum is given and discussed. First it is shown that, computing from our particular metric the linearized connections, the linearized Riemann tensor and the linearized Ricci tensor, the linearized ... More
Generalized gauge-invariance for gravitational wavesJun 16 2007Mar 24 2011The aim of this paper is to show the gauge-invariance on the response of interferometers to gravitational waves (GWs). In this process, after a review of results on the Tranverse-Traceless (TT) gauge, where, in general, the theoretical computations on ... More
Equilibrium notions and framing effectsDec 03 2010Oct 10 2011Experimental economics has repeatedly demonstrated that the Nash equilibrium makes inaccurate predictions for a vast set of games. Instead, several alternative theoretical concepts predict behavior that is much more in tune with observed data, with the ... More
A new graphical tool of outliers detection in regression models based on recursive estimationJul 02 2007We present in this paper a new tool for outliers detection in the context of multiple regression models. This graphical tool is based on recursive estimation of the parameters. Simulations were carried out to illustrate the performance of this graphical ... More
Generalized information and entropy measures in physicsFeb 07 2009Feb 14 2009The formalism of statistical mechanics can be generalized by starting from more general measures of information than the Shannon entropy and maximizing those subject to suitable constraints. We discuss some of the most important examples of information ... More
Superstatistics in high energy physics: Application to cosmic ray energy spectra and e+e- annihilationFeb 14 2009We work out a superstatistical description of high-energy scattering processes that takes into account temperature fluctuations in small volume elements. For Gamma-distributed fluctuations of the inverse temperature one effectively obtains formulas similar ... More
Correlations in superstatistical systemsSep 25 2007We review some of the properties of higher-dimensional superstatistical stochastic models. As an example, we analyse the stochastic properties of a superstatistical model of 3-dimensional Lagrangian turbulence, and compare with experimental data. Excellent ... More
Stretched exponentials from superstatisticsOct 31 2005Distributions exhibiting fat tails occur frequently in many different areas of science. A dynamical reason for fat tails can be a so-called superstatistics, where one has a superposition of local Gaussians whose variance fluctuates on a rather large spatio-temporal ... More
Superstatistical Brownian motionAug 10 2005As a main example for the superstatistics approach, we study a Brownian particle moving in a d-dimensional inhomogeneous environment with macroscopic temperature fluctuations. We discuss the average occupation time of the particle in spatial cells with ... More
Chaotic scalar fields as models for dark energyOct 17 2003Mar 31 2004We consider stochastically quantized self-interacting scalar fields as suitable models to generate dark energy in the universe. Second quantization effects lead to new and unexpected phenomena is the self interaction strength is strong. The stochastically ... More
Lagrangian acceleration statistics in turbulent flowsDec 23 2002We show that the probability densities af accelerations of Lagrangian test particles in turbulent flows as measured by Bodenschatz et al. [Nature 409, 1017 (2001)] are in excellent agreement with the predictions of a stochastic model introduced in [C. ... More
On the small-scale statistics of Lagrangian turbulenceMay 18 2001We provide evidence that the small-scale statistics of the acceleration of a test particle in high-Reynolds number Lagrangian turbulence is correctly described by Tsallis statistics with entropic index q=3/2. We present theoretical arguments why Tsallis ... More
On the Bargmann-Michel-Telegdi equations, and spin-orbit coupling: a tribute to Raymond StoraApr 22 2016The Bargmann-Michel-Telegdi equations describing the motions of a spinning, charged, relativistic particle endowed with an anomalous magnetic moment in an electromagnetic field, are reconsidered. They are shown to duly stem from the linearization of the ... More
A Remark to the Theorem of Le Calvez and YoccozMay 28 2016The theorem of Le Calvez and Yoccoz states that there are no minimal homeomorphism on the finite punctered 2-dimensional sphere S 2 . We show that this does not hold for other surfaces. Moreover, we discuss why the fast-conjugation-method fails in the ... More
High- and low-conductance NMDA receptors are present in layer 4 spiny stellate and layer 2/3 pyramidal neurons of mouse barrel cortexApr 14 2016Sep 05 2016NMDA receptors are ion channels activated by the neurotransmitter glutamate in the mammalian brain and are important in synaptic function and plasticity, but are also found in extrasynaptic locations and influence neuronal excitability. There are different ... More
Formation of protostellar jets as two-component outflows from star-disk magnetospheresOct 22 2008Axisymmetric magnetohydrodynamic (MHD) simulations have been applied to investigate the interrelation of a central stellar magnetosphere and stellar wind with a surrounding magnetized disk outflow and how the overall formation of a large scale jet is ... More
Stationary models of relativistic magnetohydrodynamic jetsNov 11 2002Highly relativistic jets are most probably driven by strong magnetic fields and are launched from the accretion disk surrounding a central black hole. In this paper we review some of our recent results considering the two-dimensional magnetic field structure ... More
Magnetohydrodynamic jets from different magnetic field configurationsNov 20 2008Using axisymmetric MHD simulations we investigate how the overall jet formation is affected by a variation in the disk magnetic flux profile and/or the existence of a central stellar magnetosphere. Our simulations evolve from an initial, hydrostatic equilibrium ... More
Relativistic MHD jets and the GRBsNov 01 2002Nov 04 2002High velocity highly collimated beams of plasma -- the jets -- are known as a general phenomenon among astrophysical sources of different energy and spatial scale. The common MHD scenario of astrophysical jet formation allows to describe the different ... More