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Results for "Markus Nagel"

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Exploring the Physical Layer Frontiers of Cellular Uplink - The Vienna LTE-A SimulatorSep 08 2015Communication systems in practice are subject to many technical/technological constraints and restrictions. MIMO processing in current wireless communications, as an example, mostly employs codebook based pre-coding to save computational complexity at ... More
Triple gauge couplings in polarised e-e+ -> W-W+ and their measurement using optimal observablesSep 19 2002The sensitivity of optimal integrated observables to electroweak triple gauge couplings is investigated for the process e-e+ -> W-W+ -> 4 fermions at future linear colliders. By a suitable reparameterisation of the couplings we achieve that all 28 coupling ... More
Probing triple gauge couplings with transverse beam polarisation in e+e- -> W+W-Jun 25 2003Sep 11 2003The prospects of measuring triple gauge couplings in W pair production at future linear colliders with transverse beam polarisation are studied. We consider CP conserving and CP violating couplings with both real and imaginary parts. The maximum achievable ... More
On the consistency of cell division processesDec 02 2013For a class of cell division processes, generating tessellations of the Euclidean space $\mathbb{R}^d$, spatial consistency is investigated. This addresses the problem whether the distribution of these tessellations, restricted to a bounded set $V$, depends ... More
Diagonal Minkowski classes, zonoid equivalence, and stable lawsJun 21 2018We consider the family of convex bodies obtained as transformations of a convex body $K$ by diagonal matrices, their Minkowski sums, and limits of them in the Hausdorff metric. We fix $K$ and consider these sums and their limits as an integral transform ... More
Glicci idealsAug 31 2012A central problem in liaison theory is to decide whether every arithmetically Cohen-Macaulay subscheme of projective $n$-space can be linked by a finite number of arithmetically Gorenstein schemes to a complete intersection. We show that this can be indeed ... More
Glicci simplicial complexesApr 24 2007One of the main open questions in liaison theory is whether every homogeneous Cohen-Macaulay ideal in a polynomial ring is glicci, i.e. if it is in the G-liaison class of a complete intersection. We give an affirmative answer to this question for Stanley-Reisner ... More
Stably slice disks of linksJan 05 2019We define the stabilizing number $\operatorname{sn}(K)$ of a knot $K \subset S^3$ as the minimal number $n$ of $S^2 \times S^2$ connected summands required for $K$ to bound a nullhomotopic locally flat disc in $D^4 # n S^2 \times S^2$. This quantity is ... More
The largest order statistics for the inradius in an isotropic STIT tessellationDec 28 2018A planar stationary and isotropic STIT tessellation at time $t>0$ is observed in the window $W_\rho={t^{-1}}\sqrt{\pi \ \rho}\cdot [-\frac{1}{2},\frac{1}{2}]^2$, for $\rho>0$. With each cell of the tessellation, we associate the inradius, which is the ... More
Numerical MacaulificationFeb 10 2012An unpublished example due to Joe Harris from 1983 (or earlier) gave two smooth space curves with the same Hilbert function, but one of the curves was arithmetically Cohen-Macaulay (ACM) and the other was not. Starting with an arbitrary homogeneous ideal ... More
Monomial and toric ideals associated to Ferrers graphsSep 13 2006Each partition $\lambda = (\lambda_1, \lambda_2, ..., \lambda_n)$ determines a so-called Ferrers tableau or, equivalently, a Ferrers bipartite graph. Its edge ideal, dubbed Ferrers ideal, is a squarefree monomial ideal that is generated by quadrics. We ... More
Minimal links and a result of GaetaApr 03 2008If $V$ is an equidimensional codimension $c$ subscheme of an $n$-dimensional projective space, and $V$ is linked to $V'$ by a complete intersection $X$, then we say that $V$ is {\em minimally linked} to $V'$ if $X$ is a codimension $c$ complete intersection ... More
Liaison and Related Topics: Notes from the Torino Workshop/SchoolMay 14 2002These are the expanded and detailed notes of the lectures given by the authors during the school and workshop entitled "Liaison and Related Topics," held at the Politecnico di Torino during the period October 1-5, 2001. In these notes we have attempted ... More
The $β$-Mixing Rate of STIT TessellationsJun 11 2014We consider homogeneous STIT tessellations $Y$ in the $\ell$-dimensional Euclidean space $R^\ell$ and show that the (spatial) $\beta$-mixing rate converges to zero.
On the capacity functional of excursion sets of Gaussian random fields on $\R^2$Oct 28 2014When a random field $(X_t, \ t\in {\mathbb R}^2)$ is thresholded on a given level $u$, the excursion set is given by its indicator $~1_{[u, \infty)}(X_t)$. The purpose of this work is to study functionals (as established in stochastic geometry) of these ... More
STIT Tessellations -- Ergodic Limit Theorems and Bounds for the Speed of ConvergenceSep 05 2016We consider homogeneous STIT tessellations in the $\ell$-dimensional Euclidean space ${\mathbb R}^\ell$. Based on results for the spatial $\beta$-mixing coefficient an upper bound for the variance of additive functionals of tessellations is derived, using ... More
Ergodic Description of STIT TessellationsNov 09 2010Let (Y_t: t > 0) be the STIT tessellation process. We show that for all polytopes W with nonempty interior and all a>1, the renormalized random sequence (a^n Y_{a^n}: n integer) induced in W, is a finitary factor of a Bernoulli shift. As a corollary we ... More
Equivariant Hilbert Series in non-Noetherian Polynomial RingsOct 09 2015Oct 19 2015We introduce and study equivariant Hilbert series of ideals in polynomial rings in countably many variables that are invariant under a suitable action of a symmetric group or the monoid $Inc(\mathbb{N})$ of strictly increasing functions. Our first main ... More
STIT Process and TreesNov 12 2014Nov 13 2014We study several constructions of the STIT tessellation process in a window of $\RR^\ell$ and supply an exact formula for its transition probability.
Criteria for componentwise linearityAug 19 2011Oct 11 2011We establish characteristic-free criteria for the componentwise linearity of graded ideals. As applications, we classify the componentwise linear ideals among the Gorenstein ideals, the standard determinantal ideals, and the ideals generated by the submaximal ... More
Regenerative processes for Poisson zero polytopesAug 29 2017Let $(M_t: t > 0)$ be a Markov process of tessellations of ${\mathbb R}^\ell$ and $({\cal C}_t:\, t > 0)$ the process of their zero cells (zero polytopes) which has the same distribution as the corresponding process for Poisson hyperplane tessellations. ... More
Data-Free Quantization through Weight Equalization and Bias CorrectionJun 11 2019We introduce a data-free quantization method for deep neural networks that does not require fine-tuning or hyperparameter selection. It achieves near-original model performance on common computer vision architectures and tasks. 8-bit fixed-point quantization ... More
Tetrahedral CurvesJul 16 2004A tetrahedral curve is a space curve whose defining ideal is an intersection of powers of monomial prime ideals of height two. It is supported on a tetrahedral configuration of lines. Schwartau described when certain such curves are ACM, namely he restricted ... More
Reduced arithmetically Gorenstein schemes and simplicial polytopes with maximal Betti numbersMar 28 2001An SI-sequence is a finite sequence of positive integers which is symmetric, unimodal and satisfies a certain growth condition. These are known to correspond precisely to the possible Hilbert functions of Artinian Gorenstein algebras with the Weak Lefschetz ... More
The weak Lefschetz property, monomial ideals, and lozengesSep 18 2009We study the weak Lefschetz property and the Hilbert function of level Artinian monomial almost complete intersections in three variables. Several such families are shown to have the weak Lefschetz property if the characteristic of the base field is zero ... More
Enumerations of lozenge tilings, lattice paths, and perfect matchings and the weak Lefschetz propertyMay 06 2013MacMahon enumerated the plane partitions in an $a \times b \times c$ box. These are in bijection to lozenge tilings of a hexagon, to certain perfect matchings, and to families of non-intersecting lattice paths. In this work we consider more general regions, ... More
Hyperplane sections and the subtlety of the Lefschetz propertiesDec 12 2010The weak and strong Lefschetz properties are two basic properties that Artinian algebras may have. Both Lefschetz properties may vary under small perturbations or changes of the characteristic. We study these subtleties by proposing a systematic way of ... More
Enumerations deciding the weak Lefschetz propertyMay 30 2011Dec 20 2011We introduce a natural correspondence between artinian monomial almost complete intersections in three variables and punctured hexagonal regions. We use this correspondence to investigate the algebras for the presence of the weak Lefschetz property. In ... More
Quantum dynamics in transverse-field Ising models from classical networksJul 20 2017Jan 23 2018The efficient representation of quantum many-body states with classical resources is a key challenge in quantum many-body theory. In this work we analytically construct classical networks for the description of the quantum dynamics in transverse-field ... More
The Multiplicity Conjecture in low codimensionsOct 22 2004We establish the multiplicity conjecture of Herzog, Huneke, and Srinivasan about the multiplicity of graded Cohen-Macaulay algebras over a field, for codimension two algebras and for Gorenstein algebras of codimension three. In fact, we prove stronger ... More
Multivariable signatures, genus bounds and $0.5$-solvable cobordismsMar 22 2017Jan 31 2019We refine prior bounds on how the multivariable signature and the nullity of a link change under link cobordisms. The formula generalizes a series of results about the 4-genus having their origins in the Murasugi-Tristram inequality, and at the same time ... More
Bounds for the Castelnuovo-Mumford regularity of modulesSep 01 2006We establish bounds for the Castelnuovo-Mumford regularity of a finitely generated graded module and its symmetric powers in terms of the degrees of the generators of the module and the degrees of their relations. We extend to modules (and improve) the ... More
Discretisation of stochastic control problems for continuous time dynamics with delayFeb 17 2006As a main step in the numerical solution of control problems in continuous time, the controlled process is approximated by sequences of controlled Markov chains, thus discretising time and space. A new feature in this context is to allow for delay in ... More
The speed of biased random walk among random conductancesApr 28 2017We consider biased random walk among iid, uniformly elliptic conductances on $\mathbb{Z}^d$, and investigate the monotonicity of the velocity as a function of the bias. It is not hard to see that if the bias is large enough, the velocity is increasing ... More
Representation varieties detect essential surfacesApr 03 2016Extending Culler-Shalen theory, Hara and the second author presented a way to construct certain kinds of branched surfaces in a $3$-manifold from an ideal point of a curve in the $\operatorname{SL}_n$-character variety. There exists an essential surface ... More
Extensions of the Multiplicity ConjectureMay 11 2005The Multiplicity conjecture of Herzog, Huneke, and Srinivasan states an upper bound for the multiplicity of any graded $k$-algebra as well as a lower bound for Cohen-Macaulay algebras. In this note we extend this conjecture in several directions. We discuss ... More
Groebner bases via linkageAug 31 2010Jun 03 2011In this paper, we give a sufficient condition for a set $\mathal G$ of polynomials to be a Gr\"obner basis with respect to a given term-order for the ideal $I$ that it generates. Our criterion depends on the linkage pattern of the ideal $I$ and of the ... More
Gamma-ray halos as a measure of intergalactic magnetic fields: a classical moment problemApr 27 2011The presence of weak intergalactic magnetic fields can be studied by their effect on electro-magnetic cascades induced by multi-TeV gamma-rays in the cosmic radiation background. Small deflections of secondary electrons and positrons as the cascade develops ... More
The Hubble diagram as a probe of mini-charged particlesApr 07 2009The luminosity-redshift relation of cosmological standard candles provides information about the relative energy composition of our Universe. In particular, the observation of type Ia supernovae up to redshift of z~2 indicate a universe which is dominated ... More
Exotic Neutrino Interactions in Cosmic RaysNov 29 2006The spectrum of extra-galactic cosmic rays (CRs) is expected to follow the Greisen-Zatsepin-Kuzmin (GZK) cutoff at about 5x10^10 GeV which results from energy losses of charged nuclei in the cosmic microwave background. So far the confrontation of this ... More
Strongly Interacting Astrophysical NeutrinosNov 16 2005The origin and chemical composition of ultra high energy cosmic rays is still an open question in astroparticle physics. The observed large-scale isotropy and also direct composition measurements can be interpreted as an extragalactic proton dominance ... More
On the possiblity of using vertically pointing Central Laser Facilities to calibrate the Cherenkov Telescope ArrayApr 22 2014A Central Laser Facility is a system composed of a laser placed at a certain distance from a light-detector array, emitting fast light pulses, typically in the vertical direction, with the aim to calibrate that array. During calibration runs, all detectors ... More
OPE-AlgebrasSep 03 2002Sep 20 2002In hep-th/0010293 Kapustin and Orlov introduce the notion of an OPE-algebra and propose that it formalizes conformal field theories in the same way as vertex algebras formalize chiral algebras, i.e. the subalgebras of holomorphic fields of conformal field ... More
Weak Positivity and Dyson's LemmaApr 02 2001We state and prove a version of Dyson's Lemma for a product of smooth projective varieties of arbitrary dimension using positivity methods.
Search for Antimatter with the AMS Cosmic Ray DetectorMar 28 2003Antimatter search results of the Alpha Magnetic Spectrometer (AMS) detector are presented. About 100 million triggers were collected in the 1998 precursor flight onboard space shuttle Discovery. This ten day mission exposed the detector on a 51.7 degrees ... More
Modeling the Emission Processes in BlazarsAug 31 2006Blazars are the most violent steady/recurrent sources of high-energy gamma-ray emission in the known Universe. They are prominent emitters of electromagnetic radiation throughout the entire electromagnetic spectrum. The observable radiation most likely ... More
The Harder-Narasimhan system in quantum groups and cohomology of quiver moduliApr 04 2002Methods of Harder and Narasimhan from the theory of moduli of vector bundles are applied to moduli of quiver representations. Using the Hall algebra approach to quantum groups, an analog of the Harder-Narasimhan recursion is constructed inside the quantized ... More
Gliders, Ether and TrianglesDec 01 2010This is a study of the about structures in one-dimensional cellular automata, with the elementary cellular automaton Rule 54 as example. It uses the formalism of "flexible time" to derive expressions that characterise triangles, gliders, and and periodic ... More
Toric Varieties as Spectra of Homogeneous Prime IdealsJun 06 2002Aug 06 2009We describe the construction of a class of toric varieties as spectra of homogeneous prime ideals.
Charge Relaxation in the Presence of Shot Noise in Coulomb Coupled Mesoscopic SystemsJun 25 1999In the presence of shot noise the charge on a mesoscopic conductor fluctuates. We are interested in the charge fluctuations which arise if the conductor is in the proximity of a gate to which it is coupled by long range Coulomb forces only. Specifically ... More
Charge densities and charge noise in mesoscopic conductorsDec 18 2001We introduce a hierarchy of density of states to characterize the charge distribution in a mesoscopic conductor. At the bottom of this hierarchy are the partial density of states which represent the contribution to the local density of states if both ... More
Mass formulae for a class of nonrotating black holesMar 06 1997In the presence of a Killing symmetry, various self-gravitating field theories with massless scalars (moduli) and vector fields reduce to sigma-models, effectively coupled to 3-dimensional gravity. We argue that this particular structure of the Einstein-matter ... More
Physical limits to magnetogeneticsApr 05 2016Jul 04 2016This is an analysis of how magnetic fields affect biological molecules and cells. It was prompted by a series of prominent reports regarding magnetism in biological systems. The first claims to have identified a protein complex that acts like a compass ... More
The Density-Potential Mapping in Quantum DynamicsOct 18 2016This work studies in detail the possibility of defining a one-to-one mapping from charge densities as obtained by the time-dependent Schr\"odinger equation to external potentials. Such a mapping is provided by the Runge-Gross theorem and lies at the very ... More
Advancing Trace Recovery Evaluation - Applied Information Retrieval in a Software Engineering ContextFeb 24 2016Successful development of software systems involves efficient navigation among software artifacts. One state-of-practice approach to structure information is to establish trace links between artifacts, a practice that is also enforced by several development ... More
The Canonical 2-Gerbe of a Complex ManifoldJan 19 2016We present the construction of a holomorphic bundle 2-gerbe for each complex manifold, a higher analog of the canonical line bundle. It is a geometric representative of the second Beilinson-Chern class. Also, an Atiyah class for gerbes is introduced and ... More
Irreducible decomposition of strain gradient tensor in isotropic strain gradient elasticityApr 25 2016In isotropic strain gradient elasticity, we decompose the strain gradient tensor into its irreducible pieces under the n-dimensional orthogonal group O(n). Using the Young tableau method for traceless tensors, four irreducible pieces (n>2), which are ... More
Non-equilibrium interfacial tension during relaxationJun 17 2015Oct 06 2015The concept of a non-equilibrium interfacial tension, defined via the work required to deform the system such that the interfacial area is changed while the volume is conserved, is investigated theoretically in the context of the relaxation of an initial ... More
Sequential decoupling of negative-energy states in Douglas-Kroll-Hess theoryJan 23 2015Sep 25 2015Here, we review the historical development, current status, and prospects of Douglas--Kroll--Hess theory as a quantum chemical relativistic electrons-only theory.
Digit Polynomials and their application to integer factorizationJan 13 2015Dec 20 2015This paper presents the concept of digit polynomials, which leads to a deterministic and unconditional integer factorization algorithm with the runtime complexity $\mathcal{O}(N^{1/4+\epsilon})$. Strassen's well known factoring approach is a special case ... More
A nonsingular solution of the edge dislocation in the gauge theory of dislocationsAug 19 2002Jan 28 2003A (linear) nonsingular solution for the edge dislocation in the translational gauge theory of defects is presented. The stress function method is used and a modified stress function is obtained. All field quantities are globally defined and the solution ... More
Dislocation theory as a 3-dimensional translation gauge theoryJun 19 2000We consider the static elastoplastic theory of dislocations in an elastoplastic material. We use a Yang-Mills type Lagrangian (the teleparallel equivalent of Hilbert-Einstein Lagrangian) and some Lagrangians with anisotropic constitutive laws. The translational ... More
On the correspondence between a screw dislocation in gradient elasticity and a regularized vortexMay 28 2004Aug 17 2004We show the correspondence between a screw dislocation in gradient elasticity and a regularized vortex. The effective Burgers vector, nonsingular distortion and stress fields of a screw dislocation and the effective circulation, smoothed velocity and ... More
A reduction of integer factorization to modular tetrationJul 16 2017Feb 13 2018Let $a,k\in\mathbb{N}$. For the $k-1$-th iterate of the exponential function $x\mapsto a^x$, also known as tetration, we write \[ ^k a:=a^{a^{.^{.^{.^{a}}}}}. \] In this paper, we show how an efficient algorithm for tetration modulo natural numbers $N$ ... More
Double Q($σ$) and Q($σ, λ$): Unifying Reinforcement Learning Control AlgorithmsNov 05 2017Temporal-difference (TD) learning is an important field in reinforcement learning. Sarsa and Q-Learning are among the most used TD algorithms. The Q($\sigma$) algorithm (Sutton and Barto (2017)) unifies both. This paper extends the Q($\sigma$) algorithm ... More
Autonomic Management in a Distributed Storage SystemJul 02 2010This thesis investigates the application of autonomic management to a distributed storage system. Effects on performance and resource consumption were measured in experiments, which were carried out in a local area test-bed. The experiments were conducted ... More
The asymptotic behavior of limit-periodic functions on primes and an application to k-free numbersSep 26 2016We use the circle method to evaluate the behavior of limit-periodic functions on primes. For those limit-periodic functions that satisfy a kind of Barban-Davenport-Halberstam condition and whose singular series converge fast enough, we can evaluate their ... More
Purely electronic transport and localization in the Bose glassSep 11 2009Oct 26 2009We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence ... More
Error bounds for spectral enhancement which are based on variable Hilbert scale inequalitiesNov 13 2009Spectral enhancement -- which aims to undo spectral broadening -- leads to integral equations which are ill-posed and require special regularisation techniques for their solution. Even when an optimal regularisation technique is used, however, the errors ... More
On Semi-Fredholm Band-Dominated OperatorsJul 30 2014In this paper we study the semi-Fredholm property of band-dominated operators $A$ and prove that it already implies the Fredholmness of $A$ in all cases where this is not disqualified by obvious reasons. Moreover, this observation is applied to show that ... More
Neutrino Sources from a Multi-Messenger PerspectiveNov 19 2018The field of high-energy neutrino astronomy is undergoing a rapid evolution. After the discovery of a diffuse flux of astrophysical TeV-PeV neutrinos in 2013, the IceCube observatory has recently found first compelling evidence for neutrino emission from ... More
Dynamical quantum phase transitions: a brief surveyNov 06 2018Nonequilibrium states of closed quantum many-body systems defy a thermodynamic description. As a consequence, constraints such as the principle of equal a priori probabilities in the microcanonical ensemble can be relaxed, which can lead to quantum states ... More
An Immersed Boundary Method with Direct Forcing for the Simulation of Particulate FlowsSep 21 2018We present an improved method for computing incompressible viscous flow around suspended rigid particles using a fixed and uniform computational grid. The main idea is to incorporate Peskin's regularized delta function approach [Acta Numerica 11 (2002) ... More
Knapsack in hyperbolic groupsJul 18 2018Apr 09 2019Recently knapsack problems have been generalized from the integers to arbitrary finitely generated groups. The knapsack problem for a finitely generated group $G$ is the following decision problem: given a tuple $(g, g_1, \ldots, g_k)$ of elements of ... More
The strong Frobenius numbers for cyclic defect blocks are equal to oneMay 22 2018The purpose of this note is to provide a reference for the fact that the strong Frobenius number, in the sense of Eaton and Livesey, of a block of a finite group with a cyclic defect group is equal to one. This answers a question of Farrell and Kessar. ... More
Inversion of circular means and the wave equation on convex planar domainsJun 06 2012Jan 19 2013We study the problem of recovering the initial data of the two dimensional wave equation from values of its solution on the boundary $\partial \Om$ of a smooth convex bounded domain $\Om \subset \R^2$. As a main result we establish back-projection type ... More
On the form of the large deviation rate function for the empirical measures of weakly interacting systemsAug 02 2012Oct 16 2014A basic result of large deviations theory is Sanov's theorem, which states that the sequence of empirical measures of independent and identically distributed samples satisfies the large deviation principle with rate function given by relative entropy ... More
Martingale inequalities for spline sequencesDec 19 2018We show that D. L\'{e}pingle's $L_1(\ell_2)$-inequality \begin{equation*} \Big\| \big( \sum_n \mathbb E[f_n | \mathscr F_{n-1}]^2 \big)^{1/2}\Big\|_1 \leq 2\cdot \Big\| \big( \sum_n f_n^2 \big)^{1/2} \Big\|_1, \qquad f_n\in\mathscr F_n, \end{equation*} ... More
Density Classification Quality of the Traffic-majority RulesSep 11 2014Mar 01 2015The density classification task is a famous problem in the theory of cellular automata. It is unsolvable for deterministic automata, but recently solutions for stochastic cellular automata have been found. One of them is a set of stochastic transition ... More
Lattice Homomorphisms between Sobolev SpacesMay 30 2008Jul 17 2008We show that every vector lattice homomorphism $T$ between Sobolev spaces can be represented by a composition and a multiplication, that is, $T$ is of the form $Tu(x)=u(h(x))g(x)$ for quasi every/almost every $x$ and all $u$.
Cusum tests for changes in the Hurst exponent and volatility of fractional Brownian motionApr 09 2019In this note, we construct cusum change-point tests for the Hurst exponent and the volatility of a discretely observed fractional Brownian motion. As a statistical application of the functional Breuer-Major theorems by B\'egyn (2007) and Nourdin and Nualart ... More
Slices of motivic Landweber spectraMay 21 2008Apr 24 2009We show that the Conjecture of Voevodsky concerning slices of the algebraic cobordism spectrum MGL implies a general statement about the slices of motivic Landweber spectra. In particular it confirms the possible approach suggested by Voevodsky for the ... More
Module Border BasesFeb 26 2013In this paper, we generalize the notion of border bases of zero-dimensional polynomial ideals to the module setting. To this end, we introduce order modules as a generalization of order ideals and module border bases of submodules with finite codimension ... More
A Gröbner basis proof of the flat extension theorem for moment matricesJan 28 2008Jan 19 2009This paper has been withdrawn by the author since $U$ in Lemma 2 is in general not a subspace.
Properties of Extensive Air ShowersFeb 12 2004Some general properties of extensive air showers are discussed. The main focus is put on the longitudinal development, in particular the energy flow, and on the lateral distribution of different air shower components. The intention of the paper is to ... More
On the non-uniform motion of dislocations: The retarded elastic fields, the retarded dislocation tensor potentials and the Liénard-Wiechert tensor potentialsOct 11 2012The purpose of this paper is the fundamental theory of the non-uniform motion of dislocations in two and three space-dimensions. We investigate the non-uniform motion of an arbitrary distribution of dislocations, a dislocation loop and straight dislocations ... More
The elastodynamic Liénard-Wiechert potentials and elastic fields of non-uniformly moving point and line forcesMay 23 2012The purpose of this paper is to investigate the fundamental problem of the non-uniform subsonic motion of a point force and line forces in an unbounded, homogeneous, isotropic medium in analogy to the electromagnetic Li\'enard-Wiechert potentials. The ... More
An elastoplastic theory of dislocations as a physical field theory with torsionMay 14 2001Feb 25 2002We consider a static theory of dislocations with moment stress in an anisotropic or isotropic elastoplastical material as a T(3)-gauge theory. We obtain Yang-Mills type field equations which express the force and the moment equilibrium. Additionally, ... More
OT SIMPLE - a construction-kit approach to Optimality Theory implementationNov 12 1996This paper details a simple approach to the implementation of Optimality Theory (OT, Prince and Smolensky 1993) on a computer, in part reusing standard system software. In a nutshell, OT's GENerating source is implemented as a BinProlog program interpreting ... More
Pointwise estimates for B-spline Gram matrix inversesDec 12 2012Nov 26 2013We present a new method for proving a certain geometric-decay inequality for entries of inverses of B-spline Gram matrices, which is given in [Passenbrunner,Shadrin 2013, arXiv:1308.4824].
Brauer spaces for commutative rings and structured ring spectraOct 13 2011Jul 30 2013Using an analogy between the Brauer groups in algebra and the Whitehead groups in topology, we first use methods of algebraic K-theory to give a natural definition of Brauer spectra for commutative rings, such that their homotopy groups are given by the ... More
A non-trivial ghost kernel for the equivariant stable cohomotopy of projective spacesOct 11 2011It is shown that the ghost kernel for certain equivariant stable cohomotopy groups of projective spaces is non-trivial. The proof is based on the Borel cohomology Adams spectral sequence and the calculations with the Steenrod algebra afforded by it.
Anomalous Anisotropies of Cosmic Rays from Turbulent Magnetic FieldsOct 21 2013Jan 15 2014The propagation of cosmic rays (CRs) in turbulent interstellar magnetic fields is typically described as a spatial diffusion process. This formalism predicts only a small deviation from an isotropic CR distribution in the form of a dipole in the direction ... More
Supersymmetry on the RocksOct 26 2006In R-parity conserving supersymmetric (SUSY) models the lightest SUSY particle (LSP) is stable and a candidate for dark matter. Depending on the coupling and mass of this particle the life time of the next-to-lightest SUSY particle (NLSP) may be large ... More
Models for the Spectral Energy Distributions and Variability of BlazarsJun 25 2010In this review, recent progress in theoretical models for blazar emission will be summarized. The salient features of both leptonic and lepto-hadronic approaches to modeling blazar spectral energy distributions will be reviewed. I will present sample ... More
The Polarization Dependence of Gamma-Gamma Absorption - Implications for Gamma-Ray Bursts and BlazarsSep 05 2014This paper presents an analysis of the dependence of the opacity for high-energy gamma-rays to gamma-gamma absorption by low-energy photons, on the polarization of the gamma-ray and target photons. This process has so far only been considered using the ... More
Higgs Physics at a Future e+e- Linear ColliderJul 26 2001This letter reviews the potential of a high luminosity e+e- linear collider (LC) in the precision study of the Higgs boson profile. The complementarity with the Large Hadron Collider (LHC) Higgs physics program is briefly discussed.
Flexible Time and the Evolution of One-Dimensional Cellular AutomataDec 22 2008Jul 17 2010Here I describe a view of the evolution of cellular automata that allows to operate on larger structures. Instead of calculating the next state of all cells in one step, the method here developed uses a time slice that can proceed at different places ... More
The use of geometric and quantum group techniques for wild quiversApr 15 2003This overview paper reviews several results relating the representation theory of quivers to algebraic geometry and quantum group theory. (Potential) applications to the study of the representation theory of wild quivers are discussed. To appear in the ... More
Quivers, desingularizations and canonical basesApr 30 2001A class of desingularizations for orbit closures of representations of Dynkin quivers is constructed, which can be viewed as a graded analogue of the Springer resolution. A stratification of the singular fibres is introduced; its geometry and combinatorics ... More