Results for "Andrew Meyer"

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Reachability Analysis for Robustness Evaluation of the Sit-To-Stand Movement for Powered Lower Limb OrthosesMay 28 2018A sensitivity-based approach for computing over-approximations of reachable sets, in the presence of constant parameter uncertainties and a single initial state, is used to analyze a three-link planar robot modeling a Powered Lower Limb Orthosis and its ... More
Blade-shaped (PKN) Hydraulic Fracture Driven By A Turbulent Fluid In An Impermeable RockSep 05 2016High flow rate, water-driven hydraulic fractures are more common now than ever in the oil and gas industry. Although the fractures are small, the high injection rate and low viscosity of the water, lead to high Reynolds numbers and potentially turbulence ... More
A first search for a stochastic gravitational-wave background from ultralight bosonsDec 22 2018In this work, we develop a Bayesian data analysis framework to study the SGWB from bosonic clouds using data from Advanced LIGO and Advanced Virgo, building on previous work by Brito (2017). We further improve this model by adding a BH population ... More
Analyzing Machupo virus-receptor binding by molecular dynamics simulationsFeb 28 2013Jan 14 2014In many biological applications, we would like to be able to computationally predict mutational effects on affinity in protein-protein interactions. However, many commonly used methods to predict these effects perform poorly in important test cases. In ... More
Effect of reheating on predictions following multiple-field inflationOct 24 2017Jan 23 2018We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semi-analytic treatment of the impact of perturbative reheating on cosmological perturbations ... More
Vibrational band structure of nanoscale phononic crystalsNov 02 2015Nov 24 2017The vibrational properties of two-dimensional phononic crystals are studied with large-scale molecular dynamics simulations and finite element method calculation. The vibrational band structure derived from the molecular dynamics simulations shows the ... More
Cosmic Neutrinos and Other Light RelicsMay 18 2016Cosmological measurements of the radiation density in the early universe can be used as a sensitive probe of physics beyond the standard model. Observations of primordial light element abundances have long been used to place non-trivial constraints on ... More
High Precision Astrometry with Adaptive Optics aided ImagingMay 27 2010More than 450 exoplanets are known and this number increases nearly every day. Only a few constraints on their orbital parameters and physical characteristics can be determined, as most exoplanets are detected indirectly. Measuring the astrometric signal ... More
Theory of ProgramsJul 02 2015Dec 07 2015A general theory of programs, programming and programming languages built up from a few concepts of elementary set theory. Derives, as theorems, properties treated as axioms by classic approaches to programming. Covers sequential and concurrent computation. ... More
Towards a Calculus of Object ProgramsJul 11 2011Jul 17 2011Verifying properties of object-oriented software requires a method for handling references in a simple and intuitive way, closely related to how O-O programmers reason about their programs. The method presented here, a Calculus of Object Programs, combines ... More
Modularity experiments on $S_4$-symmetric double octicsOct 08 2018We will invest quite some computer power to find double octic threefolds that are connected to weight four modular forms.
Representations of *-algebras by unbounded operators: C*-hulls, local-global principle, and inductionJul 15 2016Sep 29 2016We define a C*-hull for a *-algebra, given a notion of integrability for its representations on Hilbert modules. We establish a local-global principle which, in many cases, characterises integrable representations on Hilbert modules through the integrable ... More
Representations of *-algebras by unbounded operators: C*-hulls, local-global principle, and inductionJul 15 2016Jul 27 2017We define a C*-hull for a *-algebra, given a notion of integrability for its representations on Hilbert modules. We establish a local-global principle which, in many cases, characterises integrable representations on Hilbert modules through the integrable ... More
Selling train tickets by SMSJul 06 2011Selling train tickets has evolved in the last ten years from queuing in the railway station, to buying tickets on the internet and printing them. Both alternatives are still viable options, though they are time consuming or need printing devices. Nowadays ... More
A Popperian Falsification of Artificial Intelligence - Lighthill DefendedApr 23 2017Apr 18 2018The area of computation called artificial intelligence (AI) is falsified by describing a previous 1972 falsification of AI by British applied mathematician James Lighthill. It is explained how Lighthill's arguments continue to apply to current AI. It ... More
A spectral interpretation for the zeros of the Riemann zeta functionDec 14 2004Aug 27 2013Based on work of Alain Connes, I have constructed a spectral interpretation for zeros of L-functions. Here we specialise this construction to the Riemann zeta function. We construct an operator on a nuclear Frechet space whose spectrum is the set of non-trivial ... More
A more general method to classify up to equivariant KK-equivalence II: Computing obstruction classesSep 23 2018We describe Universal Coefficient Theorems for the equivariant Kasparov theory for C*-algebras with an action of the group of integers or over a unique path space, using KK-valued invariants. We compare the resulting classification up to equivariant KK-equivalence ... More
Searches for New Phenomena at the Tevatron and at HERAOct 02 2006Recent results on searches for new physics at Run II of the Tevatron and highlights from HERA are reported. The searches cover many different final states and a wide range of models. All analyses have at this point led to negative results, but some interesting ... More
A Valuation Theoretic Approach to Essential DimensionFeb 24 2012In this essay we explore the notion of essential dimension using the theory of valuations of fields. Given a field extension K/k and a valuation on K that is trivial on k, we prove that the rank of the valuation cannot exceed the transcendence degree ... More
New Charm(onium) Results from CDFSep 07 2003After many upgrades to the CDF detector and to the accelerator complex, Run II began in April 2001. The new detector has improved capabilities for charm physics, and first results from the analysis of early Tevatron Run II data are reported here.
Homological algebra in bivariant K-theory and other triangulated categories. IIJan 09 2008Dec 12 2008We use homological ideals in triangulated categories to get a sufficient criterion for a pair of subcategories in a triangulated category to be complementary. We apply this criterion to construct the Baum-Connes assembly map for locally compact groups ... More
A more general method to classify up to equivariant KK-equivalence II: Computing obstruction classesSep 23 2018Apr 27 2019We describe Universal Coefficient Theorems for the equivariant Kasparov theory for C*-algebras with an action of the group of integers or over a unique path space, using KK-valued invariants. We compare the resulting classification up to equivariant KK-equivalence ... More
Unmating of rational maps, sufficient criteria and examplesOct 31 2011Douady and Hubbard introduced the operation of mating of polynomials. This identifies two filled Julia sets and the dynamics on them via external rays. In many cases one obtains a rational map. Here the opposite question is tackled. Namely we ask when ... More
Expanding Thurston maps as quotientsOct 11 2009Oct 22 2012A Thurston map is a branched covering map $f\colon S^2\to S^2$ that is postcritically finite. Mating of polynomials, introduced by Douady and Hubbard, is a method to geometrically combine the Julia sets of two polynomials (and their dynamics) to form ... More
Invariant Peano curves of expanding Thurston mapsJul 09 2009Apr 09 2013We consider Thurston maps, i.e., branched covering maps $f\colon S^2\to S^2$ that are postcritically finite. In addition, we assume that $f$ is expanding in a suitable sense. It is shown that each sufficiently high iterate $F=f^n$ of $f$ is semi-conjugate ... More
Extreme lattices and vexillar designsDec 14 2008We define a notion of vexillar design for the flag variety in the spirit of the spherical designs introduced by Delsarte, Goethals and Seidel. For a finite subgroup of the orthogonal group, we explain how conditions on the group have the orbits of any ... More
Generalized fixed point algebras and square-integrable group actionsNov 13 2000We analzye Rieffel's construction of generalized fixed point algebras in the setting of group actions on Hilbert modules. Let G be a locally compact group acting on a C*-algebra B. We construct a Hilbert module F over the reduced crossed product of G ... More
The Bivariate Normal CopulaDec 15 2009We collect well known and less known facts about the bivariate normal distribution and translate them into copula language. In addition, we prove a very general formula for the bivariate normal copula, we compute Gini's gamma, and we provide improved ... More
Fast approximate simulation of seismic waves with deep learningJul 18 2018We simulate the response of acoustic seismic waves in horizontally layered media using a deep neural network. In contrast to traditional finite-difference modelling techniques our network is able to directly approximate the recorded seismic response at ... More
Achiral symmetry breaking and positive Gaussian modulus lead to scalloped colloidal membranesOct 21 2016Nov 07 2016In the presence of a non-adsorbing polymer, monodisperse rod-like particles assemble into colloidal membranes, which are one rod-length thick liquid-like monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal monolayer membranes form ... More
Protoplanetary Disk Masses in the Young NGC 2024 ClusterJan 26 2015We present the results from a Submillimeter Array survey of the 887 micron continuum emission from the protoplanetary disks around 95 young stars in the young cluster NGC 2024. Emission was detected from 22 infrared sources, with flux densities from ~5 ... More
GPU Multisplit: an extended study of a parallel algorithmJan 05 2017May 19 2017Multisplit is a broadly useful parallel primitive that permutes its input data into contiguous buckets or bins, where the function that categorizes an element into a bucket is provided by the programmer. Due to the lack of an efficient multisplit on GPUs, ... More
Small-Scale Interstellar Na I Structure Toward M92Apr 02 2001We have used integral field echelle spectroscopy with the DensePak fiber-optic array on the KPNO WIYN telescope to observe the central 27" x 43" of the globular cluster M92 in the Na I D wavelength region at a spatial resolution of 4". Two interstellar ... More
Multiple testing of local maxima for detection of peaks in ChIP-Seq dataMay 28 2013A topological multiple testing approach to peak detection is proposed for the problem of detecting transcription factor binding sites in ChIP-Seq data. After kernel smoothing of the tag counts over the genome, the presence of a peak is tested at each ... More
Coffman deadlocks in SCOOPSep 26 2014Oct 06 2014In this paper we address the deadlock detection problem in the context of SCOOP - an OO-programming model for concurrency, recently formalized in Maude. We present the integration of a deadlock detection mechanism on top of the aforementioned formalization ... More
On the Verification of SCOOP ProgramsApr 27 2015Apr 30 2015In this paper we focus on the development of a toolbox for the verification of programs in the context of SCOOP -- an elegant concurrency model, recently formalized based on Rewriting Logic (RL) and Maude. SCOOP is implemented in Eiffel and its applicability ... More
Complete contracts through specification driversFeb 12 2016Existing techniques of Design by Contract do not allow software developers to specify complete contracts in many cases. Incomplete contracts leave room for malicious implementations. This article complements Design by Contract with a simple yet powerful ... More
Laplacian SimplicesJun 21 2017This paper initiates the study of the "Laplacian simplex" $T_G$ obtained from a finite graph $G$ by taking the convex hull of the columns of the Laplacian matrix for $G$. Basic properties of these simplices are established, and then a systematic investigation ... More
Modularity Component Analysis versus Principal Component AnalysisOct 19 2015Feb 19 2016In this paper the exact linear relation between the leading eigenvectors of the modularity matrix and the singular vectors of an uncentered data matrix is developed. Based on this analysis the concept of a modularity component is defined, and its properties ... More
An upper bound on the essential dimension of a central simple algebraJul 26 2009We prove a new upper bound on the essential p-dimension of the projective linear group PGLn.
Quasi-trees and geodesic treesFeb 20 2019Mar 04 2019A quasi-tree is a metric tree that is doubling and of bounded turning. We prove that every quasi-tree is quasisymmetrically equivalent to a geodesic tree with Hausdorff dimension arbitrarily close to 1.
Inferring coarse-grain histone-DNA interaction potentials from high-resolution structures of the nucleosomeNov 03 2014The histone-DNA interaction in the nucleosome is a fundamental mechanism of genomic compaction and regulation, which remains largely unkown despite a growing structural knowledge of the complex. Here, we propose a framework for the extraction of a nanoscale ... More
C*-Algebras for partial product systems over NFeb 20 2018Nov 23 2018We define partial product systems over N. They generalise product systems over N and Fell bundles over Z. We define Toeplitz C*-algebras and relative Cuntz-Pimsner algebras for them and show that the section C*-algebra of a Fell bundle over Z is a relative ... More
Universal deformation rings for extensions of finite subgoups of $Gl_2(\mathbb{C})$Feb 09 2016In this paper we expand on previous results, studying the extent to which one can detect fusion in certain finite groups $\Gamma$, from information about the universal deformation rings of absolutely irreducible $\mathbb{F}_p\Gamma$-modules. We consider ... More
Some functional forms of Blaschke-Santaló inequalitySep 20 2006We establish new functional versions of the Blaschke-Santal\'o inequality on the volume product of a convex body which generalize to the non-symmetric setting an inequality of K. Ball and we give a simple proof of the case of equality. As a corollary, ... More
Resolutions for representations of reductive p-adic groups via their buildingsFeb 27 2009Jul 28 2009Schneider-Stuhler and Vigneras have used cosheaves on the affine Bruhat-Tits building to construct natural finite type projective resolutions for admissible representations of reductive p-adic groups in characteristic not equal to p. We use a system of ... More
Diversity and network coherence as indicators of interdisciplinarity: Case studies in bionanoscienceJan 10 2009The multidimensional character and inherent conflict with categorisation of interdisciplinarity makes its mapping and evaluation a challenging task. We propose a conceptual framework that aims to capture interdisciplinarity in the wider sense of knowledge ... More
Integral point sets in higher dimensional affine spaces over finite fieldsJan 17 2014We consider point sets in the $m$-dimensional affine space $\mathbb{F}_q^m$ where each squared Euclidean distance of two points is a square in $\mathbb{F}_q$. It turns out that the situation in $\mathbb{F}_q^m$ is rather similar to the one of integral ... More
Modeling Heat Dissipation at the Nanoscale: An Embedding Approach for Chemical Reaction Dynamics on Metal SurfacesFeb 24 2014May 13 2014We present an embedding technique for metallic systems that makes it possible to model energy dissipation into substrate phonons during surface chemical reactions from first principles. The separation of chemical and elastic contributions to the interaction ... More
In silico Proteome Cleavage Reveals Iterative Digestion Strategy for High Sequence CoverageFeb 07 2014In the post-genome era, biologists have sought to measure the complete complement of proteins, termed proteomics. Currently, the most effective method to measure the proteome is with shotgun, or bottom-up, proteomics, in which the proteome is digested ... More
Is Privacy Controllable?Jan 28 2019One of the major views of privacy associates privacy with the control over information. This gives rise to the question how controllable privacy actually is. In this paper, we adapt certain formal methods of control theory and investigate the implications ... More
The Cambridge Jet algorithm: features and applicationsMar 12 1998Apr 02 1998Jet clustering algorithms are widely used to analyse hadronic events in high energy collisions. Recently a new clustering method, known as `Cambridge', has been introduced. In this article we present an algorithm to determine the transition values of ... More
Robustness against Power is PSPACE-completeApr 28 2014Power is a RISC architecture developed by IBM, Freescale, and several other companies and implemented in a series of POWER processors. The architecture features a relaxed memory model providing very weak guarantees with respect to the ordering and atomicity ... More
Admissible and Restrained RevisionSep 28 2011As partial justification of their framework for iterated belief revision Darwiche and Pearl convincingly argued against Boutiliers natural revision and provided a prototypical revision operator that fits into their scheme. We show that the Darwiche-Pearl ... More
AutoFrame: Automatic Frame Inference for Object-Oriented LanguagesAug 27 2018Aug 28 2018Automatic program verification has made tremendous strides, but is not yet for the masses. How do we make it less painful? This article addresses one of the obstacles: the need to specify explicit "frame clauses", expressing what properties are left unchanged ... More
Modularity of some non-rigid double octic Calabi-Yau threefoldsMay 31 2005Jul 11 2005In this paper we discuss four methods of proving modularity of Calabi--Yau threefolds with $h^{12}=1$: existence of elliptic ruled surfaces inside (Hulek-Verrill), correspondence with a product of an elliptic curve and a K3 surface (Livn\'e-Yui), correspondence ... More
Modular Calabi-Yau threefolds of level eightApr 05 2005In the studies on the modularity conjecture for rigid Calabi-Yau threefolds several examples with the unique level 8 cusp form were constructed. According to the Tate Conjecture correspondences inducing isomorphisms on the middle cohomologies should exist ... More
Top Quark PropertiesNov 23 2015Recent measurements of top-quark properties at the LHC and at the Tevatron are presented. The results include precision measurements of standard model parameters, such as the top-quark mass, the measurement of angular distributions as well as the search ... More
The Santalo-regions of a convex bodyJul 05 1997Motivated by the Blaschke-Santal\'o inequality, we define for a convex body K in ${\bf R}^n$ and for $t \in {\bf R}$ the Santal\'o-regions S(K,t) of K. We investigate properties of these sets and relate them to a concept of Affine Differential Geometry, ... More
Expanding Thurston MapsSep 19 2010Oct 10 2017We study the dynamics of Thurston maps under iteration. These are branched covering maps $f$ of 2-spheres $S^2$ with a finite set $\mathop{post}(f)$ of postcritical points. We also assume that the maps are expanding in a suitable sense. Every expanding ... More
Crossed module actions on continuous trace $C^*$-algebrasJun 03 2015Mar 03 2016We lift an action of a torus $\mathbb{T}^n$ on the spectrum of a continuous trace algebra to an action of a certain crossed module of Lie groups that is an extension of $\mathbb{R}^n$. We compute equivariant Brauer and Picard groups for this crossed module ... More
Characters and growth of admissible representations of reductive p-adic groupsAug 11 2009Mar 07 2016We use coefficient systems on the affine Bruhat-Tits building to study admissible representations of reductive p-adic groups in characteristic not equal to p. We show that the character function is locally constant and provide explicit neighbourhoods ... More
Continuous spectral decompositions of Abelian group actions on C*-algebrasMar 10 2007Let G be a locally compact Abelian group. Following Ruy Exel, we view Fell bundles over the Pontrjagin dual of G as continuous spectral decompositions of G-actions on C*-algebras. We classify such spectral decompositions using certain dense subspaces ... More
AutoAlias: Automatic Variable-Precision Alias Analysis for Object-Oriented ProgramsAug 27 2018Apr 19 2019The aliasing question (can two reference expressions point, during an execution, to the same object?) is both one of the most critical in practice, for applications ranging from compiler optimization to programmer verification, and one of the most heavily ... More
Optimal regularity and long-time behavior of solutions for the Westervelt equationFeb 20 2015We investigate an initial-boundary value problem for the quasilinear Westervelt equation which models the propagation of sound in fluidic media. We prove that, if the initial data are sufficiently small and regular, then there exists a unique global solution ... More
C*-Algebras over Topological Spaces: The Bootstrap ClassDec 10 2007Dec 11 2008We carefully define and study C*-algebras over topological spaces, possibly non-Hausdorff, and review some relevant results from point-set topology along the way. We explain the triangulated category structure on the bivariant Kasparov theory over a topological ... More
A Rank Minrelation - Majrelation CoefficientMay 09 2013Improving the detection of relevant variables using a new bivariate measure could importantly impact variable selection and large network inference methods. In this paper, we propose a new statistical coefficient that we call the rank minrelation coefficient. ... More
Continuity of the Perron RootJul 28 2014That the Perron root of a square nonnegative matrix A varies continuously with the entries in A is a corollary of theorems regarding continuity of eigenvalues or roots of polynomial equations, the proofs of which necessarily involve complex numbers. But ... More
Optimal regularity and exponential stability for the Blackstock-Crighton equation in $L_p$-spaces with Dirichlet and Neumann boundary conditionsJun 09 2015The Blackstock-Crighton equation models nonlinear acoustic wave propagation in thermo-viscous fluids. In the present work we investigate the associated inhomogeneous Dirichlet and Neumann boundary value problems in a bounded domain and prove long-time ... More
Exponential growth of some iterated monodromy groupsOct 10 2016Iterated monodromy groups of postcritically-finite rational maps form a rich class of self-similar groups with interesting properties. There are examples of such groups that have intermediate growth, as well as examples that have exponential growth. These ... More
The isotropy constant and boundary properties of convex bodiesDec 08 2015Dec 20 2015Let ${\cal K}^n$ be the set of all convex bodies in $\mathbb R^n$ endowed with the Hausdorff distance. We prove that if $K\in {\cal K}^n$ has positive generalized Gauss curvature at some point of its boundary, then $K$ is not a local maximizer for the ... More
Division Algebras With Infinite GenusJan 23 2013Aug 13 2014To what extent does the maximal subfield spectrum of a division algebra determine the isomorphism class of that algebra? It has been shown that over some fields a quaternion division algebra's isomorphism class is largely if not entirely determined by ... More
Laplacian Simplices II: A Coding Theoretic ApproachSep 09 2018This paper further investigates \emph{Laplacian simplices}. A construction by Braun and the first author associates to a simple connected graph $G$ a simplex $\cP_G$ whose vertices are the rows of the Laplacian matrix of $G$. In this paper we associate ... More
(Un)Conditional Sample Generation Based on Distribution Element TreesNov 13 2017Jun 14 2018Recently, distribution element trees (DETs) were introduced as an accurate and computationally efficient method for density estimation. In this work, we demonstrate that the DET formulation promotes an easy and inexpensive way to generate random samples ... More
Inverse semigroup actions on groupoidsOct 08 2014Jan 09 2017We define inverse semigroup actions on topological groupoids by partial equivalences. From such actions, we construct saturated Fell bundles over inverse semigroups and non-Hausdorff \'etale groupoids. We interpret these as actions on C*-algebras by Hilbert ... More
Iterated crossed products for groupoid fibrationsApr 07 2016We define and study fibrations of topological groupoids. We interpret a groupoid fibration L->H with fibre G as an action of H on G by groupoid equivalences. Our main result shows that a crossed product for an action of L is isomorphic to an iterated ... More
Homological algebra in bivariant K-theory and other triangulated categoriesFeb 06 2007Aug 11 2008Bivariant (equivariant) K-theory is the standard setting for non-commutative topology. We may carry over various techniques from homotopy theory and homological algebra to this setting. Here we do this for some basic notions from homological algebra: ... More
Global well-posedness and exponential stability for Kuznetsov's equation in L_p-spacesSep 07 2012We investigate a quasilinear initial-boundary value problem for Kuznetsov's equation with non-homogeneous Dirichlet boundary conditions. This is a model in nonlinear acoustics which describes the propagation of sound in fluidic media with applications ... More
Some consequences of the Karpenko-Merkurjev theoremNov 15 2008We use a recent theorem of N. A. Karpenko and A. S. Merkurjev to settle several questions in the theory of essential dimension.
Descent Representations of Generalized Coinvariant AlgebrasNov 30 2017Feb 23 2018The coinvariant algebra $R_n$ is a well-studied $\mathfrak{S}_n$-module that is a graded version of the regular representation of $\mathfrak{S}_n$. Using a straightening algorithm on monomials and the Garsia-Stanton basis, Adin, Brenti, and Roichman gave ... More
Relations Between Adjacency and Modularity Graph PartitioningMay 09 2015Mar 30 2019In this paper the exact linear relation between the leading eigenvector of the unnormalized modularity matrix and the eigenvectors of the adjacency matrix is developed. Based on this analysis a method to approximate the leading eigenvector of the modularity ... More
The essential dimension of the normalizer of a maximal torus in the projective linear groupSep 10 2008Let p be a prime, k be a field of characteristic different from p containing a primitive p-th root of unity and N be the normalizer of the maximal torus in the projective linear group PGLn. We compute the exact value of the essential dimension ed(N;p) ... More
Composite fermion basis for two-component Bose gasesJan 16 2017Despite its success, the composite fermion (CF) construction possesses some mathematical features that have, until recently, not been fully understood. In particular, it is known to produce wave functions that are not necessarily orthogonal, or even linearly ... More
Extended Tully-Fisher Relations using HI StackingOct 27 2015We present a new technique for the statistical evaluation of the Tully-Fisher relation (TFR) using spectral line stacking. This technique has the potential to extend TFR observations to lower masses and higher redshifts than possible through a galaxy-by-galaxy ... More
Bigness in compatible systemsAug 13 2009Apr 21 2010Clozel, Harris and Taylor have recently proved a modularity lifting theorem of the following general form: if rho is an l-adic representation of the absolute Galois group of a number field for which the residual representation rho-bar comes from a modular ... More
Average liar count for degree-2 Frobenius pseudoprimesJul 17 2017In this paper we obtain lower and upper bounds on the average number of liars for the Quadratic Frobenius Pseudoprime Test of Grantham, generalizing arguments of Erd\H{o}s and Pomerance, and Monier. These bounds are provided for both Jacobi symbol plus ... More
Quaternionic Kähler Manifolds of Cohomogeneity OneAug 21 1998Nov 24 1998Classification results are given for (i) compact quaternionic K\"ahler manifolds with a cohomogeneity-one action of a semi-simple group, (ii) certain complete hyperK\"ahler manifolds with a cohomogeneity-two action of a semi-simple group preserving each ... More
Non-Abelian Cut Constructions and Hyperkähler ModificationsFeb 09 2010We discuss a general framework for cutting constructions and reinterpret in this setting the work on non-Abelian symplectic cuts by Weitsman. We then introduce two analogous non-Abelian modification constructions for hyperk\"ahler manifolds: one modifies ... More
Toric Hypersymplectic QuotientsApr 30 2004May 06 2004We study the hypersymplectic spaces obtained as quotients of flat hypersymplectic space R^{4d} by the action of a compact Abelian group. These 4n-dimensional quotients carry a multi-Hamilitonian action of an n-torus. The image of the hypersymplectic moment ... More
Hypertoric manifolds and hyperKähler moment mapsJul 14 2016We discuss various aspects of moment map geometry in symplectic and hyperK\"ahler geometry. In particular, we classify complete hyperK\"ahler manifolds of dimension $4n$ with a tri-Hamiltonian action of a torus of dimension $n$, without any assumption ... More
Modifying hyperkaehler manifolds with circle symmetryOct 24 2005Oct 25 2005A construction is introduced for modifying hyperkaehler manifolds with tri-Hamiltonian circle action, that in favourable situations increases the second Betti number by one. This is based on the symplectic cut construction of Lerman. In 4 or 8 dimensions ... More
Magnetic screening properties of superconductor-ferromagnet bilayersMar 12 2009Sep 28 2009We study theoretically the magnetic screening properties of thin, diffusive superconductor/ferromagnet bilayers subject to a perpendicular magnetic field. We find that the effective penetration depth characterizing the magnetic response oscillates with ... More
A bicategorical interpretation for relative Cuntz--Pimsner algebrasAug 11 2017Aug 29 2017We interpret the construction of relative Cuntz-Pimsner algebras of correspondences in terms of the correspondence bicategory, as a reflector into a certain sub-bicategory. This generalises a previous characterisation of absolute Cuntz-Pimsner algebras ... More
A hybrid algorithm for parallel molecular dynamics simulationsOct 31 2016May 29 2017This article describes algorithms for the hybrid parallelization and SIMD vectorization of molecular dynamics simulations with short-range forces. The parallelization method combines domain decomposition with a thread-based parallelization approach. The ... More
Ultraviolet HST Spectroscopy of Planck Cold ClumpsJan 15 2019We report results of the first study utilizing the ultraviolet capabilities of the Hubble Space Telescope to investigate a sample of Planck Galactic Cold Clump (PGCC) sources. We have selected high-resolution spectra toward 25 stars that contain a multitude ... More
SIR epidemics in dynamic contact networksMay 15 2007Contact patterns in populations fundamentally influence the spread of infectious diseases. Current mathematical methods for epidemiological forecasting on networks largely assume that contacts between individuals are fixed, at least for the duration of ... More
Multilayer multi-configuration time-dependent Hartree method: implementation and applications to a Henon-Heiles Hamiltonian and to pyrazineDec 21 2010The multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method is discussed and a fully general implementation for any number of layers based on the recursive ML-MCTDH algorithm given by Manthe [J. Chem. Phys. {\bf 128}, 164116 (2008)] is ... More
Progress in structure recovery from low dose exposures: Mixed molecular adsorption, exploitation of symmetry and reconstruction from the minimum signal levelMar 26 2018We investigate the recovery of structures from large-area, low dose exposures that distribute the dose over many identical copies of an object. The reconstruction is done via a maximum likelihood approach that does neither require to identify nor align ... More
Evaluating the Magnetorotational Instability's Dependence on Numerical Algorithms and ResolutionFeb 26 2010We have studied saturated, MRI-driven turbulence using three-dimensional, isothermal simulations with resolutions that extend from 64 to 192 zones in each direction. The simulations were performed with several higher order Godunov algorithms. A variety ... More
An Ad-Hoc Method for Obtaining chi**2 Values from Unbinned Maximum Likelihood FitsJun 30 2008Jul 02 2008A common goal in an experimental physics analysis is to extract information from a reaction with multi-dimensional kinematics. The preferred method for such a task is typically the unbinned maximum likelihood method. In fits using this method, the likelihood ... More