Results for "Andy Hammerlindl"

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Horizontal vector fields and Seifert fiberingsMar 27 2018This paper gives a classification of vector fields which are nowhere tangent to the fibers of a Seifert fibering.
Center bunching without dynamical coherenceOct 31 2014We answer a question of Burns and Wilkinson, showing that there are open families of volume-preserving partially hyperbolic diffeomorphisms which are accessible and center bunched and neither dynamically coherent nor Anosov. We also show in the volume-preserving ... More
The dynamics of quasi-isometric foliationsOct 25 2011Mar 23 2012If the stable, center, and unstable foliations of a partially hyperbolic system are quasi-isometric, the system has Global Product Structure. This result also applies to Anosov systems and to other invariant splittings. If a partially hyperbolic system ... More
Polynomial Global Product StructureMar 23 2012An Anosov diffeomorphism is topologically conjugate to an infranilmanifold automorphism if and only if it has polynomial Global Product Structure.
Properties of compact center-stable submanifoldsDec 12 2016We show that a partially hyperbolic system can have at most a finite number of compact center-stable submanifolds. We also give sufficient conditions for these submanifolds to exist and consider the question of whether they can intersect each other.
Ergodic components of partially hyperbolic systemsSep 29 2014Oct 14 2015This paper gives a complete classification of the possible ergodic decompositions for certain open families of volume-preserving partially hyperbolic diffeomorphisms. These families include systems with compact center leaves and perturbations of Anosov ... More
On expanding foliationsMar 27 2013Nov 01 2013Certain families of manifolds which support Anosov flows do not support expanding, quasi-isometric foliations.
Constructing center-stable toriOct 20 2016We show that any weakly partially hyperbolic diffeomorphism on the 2-torus may be realized as the dynamics on a center-stable or center-unstable torus of a 3-dimensional strongly partially hyperbolic system. We also construct examples of center-stable ... More
Horizontal vector fields and Seifert fiberingsMar 27 2018Jul 01 2019This paper gives a classification of the topology of vector fields which are nowhere tangent to the fibers of a Seifert fibering.
Partial hyperbolicity on 3-dimensional nilmanifoldsMar 18 2011Nov 26 2012Every partially hyperbolic diffeomorphism on a 3-dimensional nilmanifold is leaf conjugate to a nilmanifold automorphism.
Global manifold structure of a continuous-time heterodimensional cycleJun 27 2019A heterodimensional cycle consists of a pair of heteroclinic connections between two saddle periodic orbits with unstable manifolds of different dimensions. Recent theoretical work on chaotic dynamics beyond the uniformly hyperbolic setting has shown ... More
Partial hyperbolicity and classification: a surveyNov 13 2015Apr 16 2016This paper surveys recent results on classifying partially hyperbolic diffeomorphisms. This includes the construction of branching foliations and leaf conjugacies on three-dimensional manifolds with solvable fundamental group. Classification results in ... More
Classification of systems with center-stable toriFeb 20 2017This paper gives a classification of partially hyperbolic systems in dimension 3 which have at least one torus tangent to the center-stable bundle.
Pointwise partial hyperbolicity in 3-dimensional nilmanifoldsFeb 03 2013We show the existence of a family of manifolds on which all (pointwise or absolutely) partially hyperbolic systems are dynamically coherent. This family is the set of 3-manifolds with nilpotent, non-abelian fundamental group. We further classify the partially ... More
Ergodicity and partial hyperbolicity on the 3-torusAug 28 2012If a non-ergodic, partially hyperbolic diffeomorphism on the 3-torus is homotopic to an Anosov diffeomorphism $A$, it is topologically conjugate to $A$.
Classification of partially hyperbolic diffeomorphisms in 3-manifolds with solvable fundamental groupJul 17 2013Feb 26 2015A classification of partially hyperbolic diffeomorphisms on 3-dimensional manifolds with (virtually) solvable fundamental group is obtained. If such a diffeomorphism does not admit a periodic attracting or repelling two-dimensional torus, it is dynamically ... More
Partially hyperbolic surface endomorphismsNov 22 2018Nov 28 2018We prove that a class of weakly partially hyperbolic endomorphisms on $\mathbb{T}^2$ are dynamically coherent and leaf conjugate to linear toral endomorphisms. Moreover, we give an example of a partially hyperbolic endomorphism on $\mathbb{T}^2$ which ... More
Ergodicity and partial hyperbolicity on Seifert manifoldsJul 10 2019We show that conservative partially hyperbolic diffeomorphism isotopic to the identity on Seifert 3-manifolds are ergodic.
A trajectory-free framework for analysing multiscale systemsDec 23 2014We develop algorithms built around properties of the transfer operator and Koopman operator which 1) test for possible multiscale dynamics in a given dynamical system, 2) estimate the magnitude of the time-scale separation, and finally 3) distill the ... More
Seifert manifolds admitting partially hyperbolic diffeomorphismsJan 05 2017Apr 03 2018We characterize which 3-dimensional Seifert manifolds admit transitive partially hyperbolic diffeomorphisms. In particular, a circle bundle over a higher-genus surface admits a transitive partially hyperbolic diffeomorphism if and only if it admits an ... More
A computational method to extract macroscopic variables and their dynamics in multiscale systemsOct 30 2013Sep 29 2014This paper introduces coordinate-independent methods for analysing multiscale dynamical systems using numerical techniques based on the transfer operator and its adjoint. In particular, we present a method for testing whether an arbitrary dynamical system ... More
Anomalous partially hyperbolic diffeomorphisms III: abundance and incoherenceJun 15 2017Let $M$ be a closed 3-manifold which admits an Anosov flow. In this paper we develop a technique for constructing partially hyperbolic representatives in many mapping classes of $M$. We apply this technique both in the setting of geodesic flows on closed ... More
Thick, syndetic, and piecewise syndetic subsets of Fraïssé structuresAug 15 2016We define and undertake a systematic study of thick, syndetic, and piecewise syndetic subsets of a Fra\"iss\'e structure. Each of these collections forms a family in the sense of Akin and Glasner [AG], and we define and study ultrafilters on each of these ... More
A note on minimal models for pmp actionsMar 06 2019Given a countable group $G$, we say that a metrizable flow $Y$ is model-universal if by considering the various invariant measures on $Y$, we can recover every free measure-preserving $G$-system up to isomorphism. Weiss has constructed a minimal model-universal ... More
Tightness is preserved by Legendrian surgeryApr 07 2014Dec 03 2014This paper describes a characterization of tightness of closed contact 3-manifolds in terms of supporting open book decompositions. The main result is that tightness of a closed contact 3-manifold is preserved under Legendrian surgery.
Amenability and Unique Ergodicity of Automorphism Groups of Fraïssé StructuresApr 10 2013Feb 27 2014In this paper we provide a necessary and sufficient condition for the amenability of the automorphism group of Fra\"iss\'e structures and apply it to prove the non-amenability of the automorphism groups of the directed graph $\mathbf{S}(3)$ and the Boron ... More
Visualization Drivers for Geant4Jun 28 2008This document is on Geant4 visualization tools (drivers), evaluating pros and cons of each option, including recommendations on which tools to support at Fermilab for different applications{\cite{Daniel}}. Four visualization drivers are evaluated. They ... More
High-time Resolution Astrophysics and PulsarsJan 01 2008The discovery of pulsars in 1968 heralded an era where the temporal characteristics of detectors had to be reassessed. Up to this point detector integration times would normally be measured in minutes rather seconds and definitely not on sub-second time ... More
CEDAR: tools for event generator tuningAug 20 2007Aug 30 2007I describe the work of the CEDAR collaboration in developing tools for tuning and validating Monte Carlo event generator programs. The core CEDAR task is to interface the Durham HepData database of experimental measurements to event generator validation ... More
Maximally highly proximal flowsDec 02 2018Feb 26 2019For $G$ a Polish group, we consider $G$-flows which either contain a comeager orbit or have all orbits meager. We single out a class of flows, the maximally highly proximal (MHP) flows, for which this analysis is particularly nice. In the former case, ... More
Toward a graph version of Rado's theoremFeb 12 2012An equation is called graph-regular if it always has monochromatic solutions under edge-colorings of the complete graph on the naturals. We present two Rado-like conditions which are respectively necessary and sufficient for an equation to be graph-regular. ... More
AAO Observer Number 121 (February 2012)Apr 13 2012The newsletter of the Australian Astronomical Observatory. In this issue: Using 2dF and AAOmega to Harness the Full Power of the Supernova Legacy Survey; Emission Lines in the Near Infrared: Tracing the Violent ISM; Dancing Starbugs: vacuum adhesion, ... More
Tools for event generator tuning and validationSep 26 2008I describe the current status of MCnet tools for validating the performance of event generator simulations against data, and for tuning their phenomenological free parameters. For validation, the Rivet toolkit is now a mature and complete system, with ... More
A Kruskal-Katona Type Theorem for GraphsOct 22 2007A bound on consecutive clique numbers of graphs is established. This bound is evaluated and shown to often be much better than the bound of the Kruskal-Katona theorem. A bound on non-consecutive clique numbers is also proven.
Samuel compactifications of automorphism groupsFeb 07 2018We study the Samuel compactification of the automorphism group of a countable first-order structure. A key motivating question is a problem of Ellis and a counter-conjecture by Pestov regarding the difference between $S(G)$, the Samuel compactification, ... More
Preconditioning for boundary control problems in incompressible fluid dynamicsNov 23 2015Oct 17 2017PDE-constrained optimization is a field of numerical analysis that combines the theory of PDEs, nonlinear optimization and numerical linear algebra. Optimization problems of this kind arise in many physical applications, prominently in incompressible ... More
Preconditioning for boundary control problems in incompressible fluid dynamicsNov 23 2015PDE-constrained optimization is a field of numerical analysis that combines the theory of PDEs, nonlinear optimization and numerical linear algebra. Optimization problems of this kind arise in many physical applications, prominently in incompressible ... More
The Largest Compatible Subset Problem for Phylogenetic DataMay 06 2004The phylogenetic tree construction is to infer the evolutionary relationship between species from the experimental data. However, the experimental data are often imperfect and conflicting each others. Therefore, it is important to extract the motif from ... More
Solar Neutrino DecayOct 01 1993We re-examine the neutrino decay solution to the solar neutrino problem in light of the new data from Gallex II and Kamiokande III. We compare the experimental data with the solar models of Bahcall and Pinsonneault and Turck-Chieze and find that neutrino ... More
Cosmic shear measurement with maximum likelihood and maximum a posteriori inferenceMar 28 2016We investigate the problem of noise bias in maximum likelihood and maximum a posteriori estimators for cosmic shear. We derive the leading and next-to-leading order biases and compute them in the context of galaxy ellipticity measurements, extending previous ... More
Tuning of MC generator MPI modelsJun 28 2018MC models of multiple partonic scattering inevitably introduce many free parameters, either fundamental to the models or from their integration with MC treatments of primary-scattering evolution. This non-perturbative and non-factorisable physics in particular ... More
Papers presented at the 32nd International Conference on Logic Programming (ICLP 2016)Aug 18 2016This is the list of the full papers accepted for presentation at the 32nd International Conference on Logic Programming, New York City, USA, October 18-21, 2016. In addition to the main conference itself, ICLP hosted four pre-conference workshops, the ... More
Using R and Bioconductor for proteomics data analysisMay 28 2013This review presents how R, the popular statistical environment and programming language, can be used in the frame of proteomics data analysis. A short introduction to R is given, with special emphasis on some of the features that make R and its add-on ... More
Heuristic Search as Evidential ReasoningMar 27 2013BPS, the Bayesian Problem Solver, applies probabilistic inference and decision-theoretic control to flexible, resource-constrained problem-solving. This paper focuses on the Bayesian inference mechanism in BPS, and contrasts it with those of traditional ... More
The Optimality of Satisficing SolutionsMar 27 2013This paper addresses a prevailing assumption in single-agent heuristic search theory- that problem-solving algorithms should guarantee shortest-path solutions, which are typically called optimal. Optimality implies a metric for judging solution quality, ... More
Transfer Function Synthesis without Quantifier EliminationJul 18 2012Sep 28 2012Traditionally, transfer functions have been designed manually for each operation in a program, instruction by instruction. In such a setting, a transfer function describes the semantics of a single instruction, detailing how a given abstract input state ... More
X-ray Reverberation close to the black hole in RE J1034+396Aug 18 2011In previous work, we discussed the detection of reverberation delays in the NLS1 1H0707-495. The delays originate close to the black hole. Here, we show that RE J1034+396 shows very similar lag properties. At low frequencies (< 1 \times 10-4 Hz), the ... More
Toward a Holographic Model of Superconducting FermionsNov 02 2008We use the AdS/CFT correspondence to study N=4 supersymmetric SU(Nc) Yang-Mills theory, in the limits of large Nc and large 't Hooft coupling, coupled to a number Nf of massless hypermultiplet fields in the fundamental representation of the gauge group. ... More
The mechanics of tidal streamsNov 16 2010Dec 18 2010We present an analysis of the mechanics of thin streams, which are formed following the tidal disruption of cold, low-mass clusters in the potential of a massive host galaxy. The analysis makes extensive use of action-angle variables, in which the physics ... More
The Inverse Redshift-Space Operator: Reconstructing Cosmological Density and Velocity FieldsJan 13 1999We present the linear inverse redshift space operator which maps the galaxy density field derived from redshift surveys from redshift space to real space. Expressions are presented for observers in both the CMBR and Local Group rest frames. We show how ... More
Sparse Matrix Implementation in OctaveApr 03 2006There are many classes of mathematical problems which give rise to matrices, where a large number of the elements are zero. In this case it makes sense to have a special matrix type to handle this class of problems where only the non-zero elements of ... More
Cross-correlation Tomography: Measuring Dark Energy Evolution with Weak LensingJun 03 2003Dec 15 2003A cross-correlation technique of lensing tomography is presented to measure the evolution of dark energy in the universe. The variation of the weak lensing shear with redshift around massive foreground objects like bright galaxies and clusters depends ... More
Gilman's ConjectureJun 16 2018Oct 10 2018We prove a conjecture made by Gilman in 1984 that the groups presented by finite, monadic, confluent rewriting systems are precisely the free products of free and finite groups.
Synchrony in a Boolean network model of the L-arabinose operon in Escherichia coliNov 08 2016The lactose operon in Escherichia coli was the first known gene regulatory network, and it is frequently used as a prototype for new modeling paradigms. Historically, many of these modeling frameworks use differential equations. More recently, Stigler ... More
Joint cosmological inference of standard sirens and gravitational wave weak lensingDec 06 2018Feb 21 2019We present the first joint inference of standard sirens and gravitational wave weak lensing by filtering of the same dataset. We imagine a post-LISA scenario emerging around the late 2030s when LISA will have accumulated a number of detections at high ... More
Counting numerical sets with no small atomsMay 22 2008A numerical set $S$ with Frobenius number $g$ is a set of integers with $\min(S) = 0$ and $\max(\Zbb - S)=g$, and its atom monoid is $A(S) = \setpres{n \in \Zbb}{$n+s \in S$ for all $s \in S$}$. Let $\gamma_g$ be the number of numerical sets $S$ having ... More
Powheg-Pythia matching scheme effects in NLO simulation of dijet eventsAug 11 2016One of the most important developments in Monte Carlo simulation of collider events for the LHC has been the arrival of schemes and codes for matching of parton showers to matrix elements calculated at next-to-leading order in the QCD coupling. The POWHEG ... More
Filling the gaps: Gaussian mixture models from noisy, truncated or incomplete samplesNov 17 2016We extend the common mixtures-of-Gaussians density estimation approach to account for a known sample incompleteness by simultaneous imputation from the current model. The method called GMMis generalizes existing Expectation-Maximization techniques for ... More
Are profile likelihoods likelihoods? No, but sometimes they can beMar 01 2019Mar 08 2019We offer our two cents to the ongoing discussion on whether profile likelihoods are "true" likelihood functions, by showing that the profile likelihood function can in fact be identical to a marginal likelihood in the special case of normal models. Thus, ... More
Solvability of Power Flow Equations Through Existence and Uniqueness of Complex Fixed PointApr 18 2019Variations of loading level and changes in system topological property may cause the operating point of an electric power systems to move gradually towards the verge of its transmission capability, which can lead to catastrophic outcomes such as voltage ... More
Applications of Graph Integration to Function Comparison and Malware ClassificationOct 11 2018Jul 10 2019We classify .NET files as either benign or malicious by examining directed graphs derived from the set of functions comprising the given file. Each graph is viewed probabilistically as a Markov chain where each node represents a code block of the corresponding ... More
A two-level distributed algorithm for general constrained non-convex optimization with global convergenceFeb 20 2019This paper is motivated by the desire to develop distributed algorithms for nonconvex optimization problems with complicated constraints associated with a network. The network can be a physical one, such as an electric power network, where the constraints ... More
Multivariate Location and Scatter Matrix Estimation Under Cellwise and Casewise ContaminationSep 01 2016We consider the problem of multivariate location and scatter matrix estimation when the data contain cellwise and casewise outliers. Agostinelli et al. (2015) propose a two-step approach to deal with this problem: first, apply a univariate filter to remove ... More
Multi-agent evolutionary systems for the generation of complex virtual worldsApr 20 2016Modern films, games and virtual reality applications are dependent on convincing computer graphics. Highly complex models are a requirement for the successful delivery of many scenes and environments. While workflows such as rendering, compositing and ... More
Tailoring Product Ownership in Large-Scale AgileDec 16 2018In large-scale agile projects, product owners undertake a range of challenging and varied activities beyond those conventionally associated with that role. Using in-depth research interviews from 93 practitioners working in cross-border teams, from 21 ... More
Metallic AdS/CFTMay 26 2007Sep 10 2007We use the AdS/CFT correspondence to compute the conductivity of massive N=2 hypermultiplet fields at finite baryon number density in an N=4 SU(N_c) super-Yang-Mills theory plasma in the large N_c, large 't Hooft coupling limit. The finite baryon density ... More
A First Principles Estimate of Finite Size Effects in Quark-Gluon Plasma FormationMar 05 1998Sep 28 1998Using lattice simulations of quenched QCD we estimate the finite size effects present when a gluon plasma equilibrates in a slab geometry, i.e., finite width but large transverse dimensions. Significant differences are observed in the free energy density ... More
Infinite Time Turing MachinesAug 21 1998We extend in a natural way the operation of Turing machines to infinite ordinal time, and investigate the resulting supertask theory of computability and decidability on the reals. The resulting computability theory leads to a notion of computation on ... More
An Uncontrolled Toy That Can Walk But Cannot Stand StillNov 10 1997Nov 18 1997We built a simple two-leg toy that can walk stably with no control system. It walks downhill powered only by gravity. It seems to be the first McGeer-like passive-dynamic walker that is statically unstable in all standing positions, yet is stable in motion. ... More
A computational intuition pump to examine group creativity: building on the ideas of othersMay 06 2016This paper presents a computational approach to modelling group creativity. It presents an analysis of two studies of group creativity selected from different research cultures and identifies a common theme ("idea build-up") that is then used in the formalisation ... More
Powheg-Pythia matching scheme effects in NLO simulation of dijet eventsAug 11 2016Oct 27 2016One of the most important developments in Monte Carlo simulation of collider events for the LHC has been the arrival of schemes and codes for matching of parton showers to matrix elements calculated at next-to-leading order in the QCD coupling. The POWHEG ... More
A New Voltage Stability-Constrained Optimal Power Flow Model: Sufficient Condition, SOCP Representation, and RelaxationMay 29 2017Dec 12 2017A simple characterization of the solvability of power flow equations is of great importance in the monitoring, control, and protection of power systems. In this paper, we introduce a sufficient condition for power flow Jacobian nonsingularity. We show ... More
Adaptive Re-ranking of Deep Feature for Person Re-identificationNov 21 2018Typical person re-identification (re-ID) methods train a deep CNN to extract deep features and combine them with a distance metric for the final evaluation. In this work, we focus on exploiting the full information encoded in the deep feature to boost ... More
Towards determining the neutrino mass hierarchy: weak lensing and galaxy clustering forecasts with baryons and intrinsic alignmentsMay 21 2019The capacity of Stage IV lensing surveys to measure the neutrino mass sum and differentiate between the normal and inverted mass hierarchies depends on the impact of nuisance parameters describing small-scale baryonic astrophysics and intrinsic alignments. ... More
On risk averse competitive equilibriumJun 26 2017We discuss risked competitive partial equilibrium in a setting in which agents are endowed with coherent risk measures. In contrast to socialplanning models, we show by example that risked equilibria are not unique, even when agents' objective functions ... More
A posteriori error estimation for the p-curl problemMay 20 2016We derive a posteriori error estimates for a semi-discrete finite element approximation of a nonlinear eddy current problem arising from applied superconductivity, known as the $p$-curl problem. In particular, we show the reliability for non-conforming ... More
Lost in Translation: Loss and Decay of Linguistic Richness in Machine TranslationJun 28 2019This work presents an empirical approach to quantifying the loss of lexical richness in Machine Translation (MT) systems compared to Human Translation (HT). Our experiments show how current MT systems indeed fail to render the lexical diversity of human ... More
Bayesian Neural Network EnsemblesNov 27 2018Ensembles of neural networks (NNs) have long been used to estimate predictive uncertainty; a small number of NNs are trained from different initialisations and sometimes on differing versions of the dataset. The variance of the ensemble's predictions ... More
Procedural urban environments for FPS gamesApr 20 2016This paper presents a novel approach to procedural generation of urban maps for First Person Shooter (FPS) games. A multi-agent evolutionary system is employed to place streets, buildings and other items inside the Unity3D game engine, resulting in playable ... More
Ranks of Quotients, Remainders and $p$-Adic Digits of MatricesJan 26 2014Jan 31 2014For a prime $p$ and a matrix $A \in \mathbb{Z}^{n \times n}$, write $A$ as $A = p (A \,\mathrm{quo}\, p) + (A \,\mathrm{rem}\, p)$ where the remainder and quotient operations are applied element-wise. Write the $p$-adic expansion of $A$ as $A = A^{[0]} ... More
On the $q$-Charlier Multiple Orthogonal PolynomialsNov 07 2014Mar 28 2015We introduce a new family of special functions, namely $q$-Charlier multiple orthogonal polynomials. These polynomials are orthogonal with respect to $q$-analogues of Poisson distributions. We focus our attention on their structural properties. Raising ... More
On the arbitrarily long-term stability of conservative methodsJul 21 2016We show the arbitrarily long-term stability of conservative methods for autonomous ODEs. Given a system of autonomous ODEs with conserved quantities, if the preimage of the conserved quantities possesses a bounded locally finite neighborhood, then the ... More
Robust regression estimation and inference in the presence of cellwise and casewise contaminationSep 08 2015Cellwise outliers are likely to occur together with casewise outliers in modern data sets with relatively large dimension. Recent work has shown that traditional robust regression methods may fail for data sets in this paradigm. The proposed method, called ... More
A Formal Model of the Safety-Critical Java Level 2 ParadigmMay 27 2018Safety-Critical Java (SCJ) introduces a new programming paradigm for applications that must be certified. The SCJ specification (JSR 302) is an Open Group Standard, but it does not include verification techniques. Previous work has addressed verification ... More
Rotation of a rigid satellite with a fluid component. A new light onto Titan's obliquitySep 14 2017We revisit the rotation dynamics of a rigid satellite with either a liquid core or a global sub-surface ocean. In both problems, the flow of the fluid component is assumed inviscid. The study of a hollow satellite with a liquid core is based on the Poincare-Hough ... More
A Symbolic Approach to Explaining Bayesian Network ClassifiersMay 09 2018We propose an approach for explaining Bayesian network classifiers, which is based on compiling such classifiers into decision functions that have a tractable and symbolic form. We introduce two types of explanations for why a classifier may have classified ... More
A tabu search method for the optimisation of fluid power circuitsMay 17 2016This paper describes the development of an efficient algorithm for the optimization of fluid power circuits. The algorithm is based around the concepts of Tabu search, where different timescale memory cycles are used as a metaheuristic to guide a hill ... More
Mainstreaming video annotation software for critical video analysisApr 20 2016The range of video annotation software currently available is set within commercially specialized professions, distributed via outdated sources or through online video hosting services. As video content becomes an increasingly significant tool for analysis, ... More
A Holographic Two-Impurity Kondo ModelOct 27 2015We propose a model of a strongly-interacting two-impurity Kondo system based on the AdS/CFT correspondence, also known as holography. In a Landau Fermi Liquid, the single-impurity Kondo effect is the screening of an impurity spin at low temperature $T$. ... More
The ADAPT System Description for the IWSLT 2018 Basque to English Translation TaskNov 14 2018In this paper we present the ADAPT system built for the Basque to English Low Resource MT Evaluation Campaign. Basque is a low-resourced, morphologically-rich language. This poses a challenge for Neural Machine Translation models which usually achieve ... More
Multi-Tier Buffer Management and Storage System Design for Non-Volatile MemoryJan 30 2019The design of the buffer manager in database management systems (DBMSs) is influenced by the performance characteristics of volatile memory (DRAM) and non-volatile storage (e.g., SSD). The key design assumptions have been that the data must be migrated ... More
Thresholds in choice behaviour and the size of travel time savingsFeb 14 2014Sep 02 2015Travel time savings are usually the most substantial economic benefit of transport infrastructure projects. However, questions surround whether small time savings are as valuable per unit as larger savings. Thresholds in individual choice behaviour are ... More
Fully implicit time-stepping schemes and non-linear solvers for systems of reaction-diffusion equationsJan 23 2015In this article we present robust, efficient and accurate fully implicit time-stepping schemes and nonlinear solvers for systems of reaction-diffusion equations. The applications of reaction-diffusion systems is abundant in the literature, from modelling ... More
Mining developer communication data streamsJul 23 2014This paper explores the concepts of modelling a software development project as a process that results in the creation of a continuous stream of data. In terms of the Jazz repository used in this research, one aspect of that stream of data would be developer ... More
Quantifying the Impact of Parameter Tuning on Nature-Inspired AlgorithmsMay 03 2013Jul 01 2013The problem of parameterization is often central to the effective deployment of nature-inspired algorithms. However, finding the optimal set of parameter values for a combination of problem instance and solution method is highly challenging, and few concrete ... More
A Chiral Magnetic Effect from AdS/CFT with FlavorJun 20 2011For (3+1)-dimensional fermions, a net axial charge and external magnetic field can lead to a current parallel to the magnetic field. This is the chiral magnetic effect. We use gauge-gravity duality to study the chiral magnetic effect in large-Nc, strongly-coupled ... More
TellTable Spreadsheet Audit: from Technical Possibility to Operating PrototypeMar 12 2008At the 2003 EuSpRIG meeting, we presented a framework and software infrastructure to generate and analyse an audit trail for a spreadsheet file. This report describes the results of a pilot implementation of this software (now called TellTable; see, ... More
Holographic Renormalization of Probe D-Branes in AdS/CFTDec 12 2005Mar 28 2006We perform holographic renormalization for probe branes in AdS_5 x S^5. We show that for four known probe D-branes wrapping an AdS_m x S^n, the counterterms needed to render the action finite are identical to those for the free, massive scalar in AdS_m ... More
Computing Convex Hulls with a Linear SolverNov 04 2003A programming tactic involving polyhedra is reported that has been widely applied in the polyhedral analysis of (constraint) logic programs. The method enables the computations of convex hulls that are required for polyhedral analysis to be coded with ... More
Reconstructing PSCz with a Generalised PIZAJun 02 2000We present a generalized version of the Path Interchange Zel'dovich Approximation (PIZA), for use with realistic galaxy redshift surveys. PIZA is a linear particle-based Lagrangian method which uses the present day positions of galaxies to reconstruct ... More