Results for "David Meder"

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Ergodicity-breaking reveals time optimal economic behavior in humansJun 11 2019Jun 12 2019Ergodicity describes an equivalence between the expectation value and the time average of observables. Applied to human behaviour, ergodic theory reveals how individuals should tolerate risk in different environments. To optimise wealth over time, agents ... More
The Gamification Design ProblemJul 03 2014Under the assumptions that (i) gamification consists of various types of users that experience game design elements differently; and (ii) gamification is deployed in order to achieve some goal in the broadest sense, we pose the gamification problem as ... More
Ergodicity-breaking reveals time optimal economic behavior in humansJun 11 2019Ergodicity describes an equivalence between the expectation value and the time average of observables. Applied to human behaviour, ergodic theory reveals how individuals should tolerate risk in different environments. To optimise wealth over time, agents ... More
Ergodicity-breaking reveals time optimal economic behavior in humansJun 11 2019Jun 19 2019Ergodicity describes an equivalence between the expectation value and the time average of observables. Applied to human behaviour, ergodic theory reveals how individuals should tolerate risk in different environments. To optimise wealth over time, agents ... More
Simple trees in complex forests: Growing Take The Best by Approximate Bayesian ComputationMay 05 2016May 14 2016How can heuristic strategies emerge from smaller building blocks? We propose Approximate Bayesian Computation as a computational solution to this problem. As a first proof of concept, we demonstrate how a heuristic decision strategy such as Take The Best ... More
Fine-Grained Authorization for Job Execution in the Grid: Design and ImplementationNov 20 2003In this paper we describe our work on enabling fine-grained authorization for resource usage and management. We address the need of virtual organizations to enforce their own polices in addition to those of the resource owners, in regard to both resource ... More
Visualizing the Template of a Chaotic AttractorJul 31 2018Sep 10 2018Chaotic attractors are solutions of deterministic processes, of which the topology can be described by templates. We consider templates of chaotic attractors bounded by a genus-1 torus described by a linking matrix. This article introduces a novel and ... More
Security for Grid ServicesJun 24 2003Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations." The dynamic and multi-institutional nature of these environments introduces challenging security issues that demand new technical ... More
The transverse proximity effect in the z ~ 2 Lyman-alpha forest suggests QSO episodic lifetimes of ~1 MyrSep 12 2008We look for signs of the H~I transverse proximity effect in the spectra of 130 QSO pairs, most with transverse separations in the plane of the sky of 0.1 -- 3 Mpc at z ~ 2.2. We expected to see a decrease in Lyman-alpha forest HI absorption in the spectrum ... More
Comet Encounters and Carbon 14Nov 26 2012The $^{14}$C production of shock-accelerated particles is calculated in terms of the total energy released in energetic particles. The recently reported 1.2% jump in the $^{14}$C content of the atmosphere in the year C.E. 775, it is found, would require ... More
Continuum Percolation for Quermass ModelJan 11 2012The continuum percolation for Markov (or Gibbs) germ-grain models is investigated. The grains are assumed circular with random radii on a compact support. The morphological interaction is the so-called Quermass interaction defined by a linear combination ... More
Randomized greedy algorithms for independent sets and matchings in regular graphs: Exact results and finite girth correctionsJul 08 2008We derive new results for the performance of a simple greedy algorithm for finding large independent sets and matchings in constant degree regular graphs. We show that for $r$-regular graphs with $n$ nodes and girth at least $g$, the algorithm finds an ... More
Two Identities relating Eisenstein series on classical groupsAug 05 2018In this paper we introduce two general identities relating Eisenstein series on split classical groups, as well as double covers of symplectic groups. The first identity can be viewed as an extension of the doubling construction introduced in [CFGK17]. ... More
The RASNIK Real-Time Relative Alignment Monitor for the CDF Inner Tracking DetectorsDec 10 2002We describe the design and operation of the RASNIK optical relative alignment system designed for and installed on the CDF inner tracking detectors. The system provides low-cost minute-by-minute alignment monitoring with submicron precision. To reduce ... More
Results for the LISA Phase Measurement System ProjectNov 01 2004Jan 11 2005This article presents some of the more topical results of a study into the LISA phase measurement system. This system is responsible for measuring the phase of the heterodyne signal caused by the interference of the laser beams between the local and far ... More
Site Disordered Spin Systems in the Gaussian Variational ApproximationJun 06 1996Dec 16 1996We define a replica field theory describing finite dimensional site disordered spin systems by introducing the notion of grand canonical disorder, where the number of spins in the system is random but quenched. A general analysis of this field theory ... More
Splitting cycles in graphsApr 26 2012The goal of this paper is to describe a sufficient condition on cycles in graphs for which the edge ideal is splittable. We give an explicit splitting function for such ideals.
Secure, Efficient Data Transport and Replica Management for High-Performance Data-Intensive ComputingMar 28 2001An emerging class of data-intensive applications involve the geographically dispersed extraction of complex scientific information from very large collections of measured or computed data. Such applications arise, for example, in experimental physics, ... More
Stable Leader Election in Population Protocols Requires Linear TimeFeb 14 2015Aug 20 2016A population protocol *stably elects a leader* if, for all $n$, starting from an initial configuration with $n$ agents each in an identical state, with probability 1 it reaches a configuration $\mathbf{y}$ that is correct (exactly one agent is in a special ... More
Binary Survival in the Outer Solar SystemMay 06 2019As indicated by their special characteristics, the cold classical Kuiper belt objects (KBOs) formed and survived at 42-47 au. Notably, they show a large fraction of equal-size binaries whose formation is probably related to the accretion of KBOs themselves. ... More
Integrals derived from the doubling methodOct 21 2018In this note, we use a basic identity, derived from the generalized doubling integrals of \cite{C-F-G-K1}, in order to explain the existence of various global Rankin-Selberg integrals for certain $L$-functions. To derive these global integrals, we use ... More
The Detection of Two Distinct High Ionization States in a QSO Lyman Limit Absorption System: Evidence for Hierarchical Galaxy Formation at z ~ 3?Jan 19 1999We have detected two high ionization phases of gas in the z ~ 2.77 partial Lyman limit system (LLS) towards QSO 1157-3143. We detect the first phase by CIV and SiIV absorption, and the second phase -- which is either warmer or undergoing larger random ... More
Hilbert function spaces and the Nevanlinna-Pick problem on the polydisc IIFeb 21 2013In \cite{ds_hfs}, a geometric procedure for constructing a Nevanlinna-Pick problem on $\D^n$ with a specified set of uniqueness was established. In this sequel we conjecture a necessary and a sufficient condition for a Nevanlinna-Pick problem on $\DT$ ... More
Wrapped microlocal sheaves on pairs of pantsApr 01 2016Inspired by the geometry of wrapped Fukaya categories, we introduce the notion of wrapped microlocal sheaves. We show that traditional microlocal sheaves are equivalent to functionals on wrapped microlocal sheaves, in analogy with the expected relation ... More
Higher Lie and Leibniz algebrasJan 08 2015Jan 10 2015Higher structures - infinity algebras and other objects up to homotopy, categorified algebras, `oidified' concepts, operads, higher categories, higher Lie theory, higher gauge theory... - are currently intensively investigated in Mathematics and Physics. ... More
The Cantor-Bendixson Rank of Certain Bridgeland-Smith Stability ConditionsDec 08 2015Jun 08 2016We provide a novel proof that the set of directions that admit a saddle connection on a meromorphic quadratic differential with at least one pole of order at least two is closed, which generalizes a result of Bridgeland and Smith, and Gaiotto, Moore, ... More
On Double-Entry Bookkeeping: The Mathematical TreatmentJul 07 2014Double-entry bookkeeping (DEB) implicitly uses a specific mathematical construction, the group of differences using pairs of unsigned numbers ("T-accounts"). That construction was only formulated abstractly in mathematics in the 19th century--even though ... More
Niépce-Bell or Turing: How to Test Odor Reproduction?Mar 29 2016Apr 28 2016In 1950 Alan Turing proposed his imitation game, better known as the Turing test, for determining whether a computer system claimed to adequately exhibit intelligence indeed does so. This work was carried out although no such system was anywhere in sight ... More
The probability of generating the symmetric group with a commutator conditionMay 30 2012Dec 08 2013Let B(n) be the set of pairs of permutations from the symmetric group of degree n with a 3-cycle commutator, and let A(n) be the set of those pairs which generate the symmetric or the alternating group of degree n. We find effective formulas for calculating ... More
A topological approach to induction theorems in Springer theorySep 16 2008We give a self-contained account of a construction due to Rossmann which lifts Springer's action of a Weyl group on the cohomology of a Springer fiber to an action on its homotopy type. We use this construction to produce a generalization of an "induction ... More
Accelerating Branes and the String/Black Hole TransitionSep 22 2005String theory in Euclidean flat space with a spacelike linear dilaton contains a D1-brane which looks like a semi-infinite hairpin. In addition to its curved shape, this ``hairpin brane'' has a condensate of the open string tachyon stretched between its ... More
Usability Meets Instant Gratification on the Semantic WebNov 10 2010This paper presents a semantic wiki prototype application named SHAWN [later WikSAR] that allows structuring concepts within a wiki environment. To entice the use of Semantic Web technologies applications need to offer both high usability and instant ... More
A combinatorial interpretation of the eigensequence for compositionJul 08 2005Jul 20 2005The monic sequence that shifts left under convolution with itself is the Catalan numbers with 130+ combinatorial interpretations. Here we establish a combinatorial interpretation for the monic sequence that shifts left under composition: it counts permutations ... More
Some bijections for restricted Motzkin pathsJul 22 2004We give several bijections among restricted Motzkin paths, explaining why various parameters on these paths are equidistributed. For example, the number of doublerise-free Motzkin paths of length n is the same as the number of peak-free Motzkin paths ... More
Pattern avoidance in circular permutationsOct 01 2002Circular permutations on {1,2,...,n} that avoid a given pattern correspond to ordinary (linear) permutations that end with n and avoid all cyclic rotations of the pattern. Three letter patterns are all but unavoidable in circular permutations and here ... More
A uniformly distributed parameter on a class of lattice pathsOct 29 2003Let G_n denote the set of lattice paths from (0,0) to (n,n) with steps of the form (i,j) where i and j are nonnegative integers, not both 0. Let D_n denote the set of paths in G_n with steps restricted to (1,0), (0,1), (1,1), so-called Delannoy paths. ... More
Similarity of the Temperature Profile formed by Fluid Flow along a WallMar 15 2016A new approach to the study of similarity of temperature profiles is presented. It is applicable for any 2-D fluid flow along an isothermal heated (cooled) wall. The approach is based on a simple concept; the area under a set of scaled temperature profile ... More
Determination through Universals: An Application of Category Theory in the Life SciencesMay 29 2013Category theory has foundational importance because it provides conceptual lenses to characterize what is important and universal in mathematics---with adjunctions being the primary lense. If adjunctions are so important in mathematics, then perhaps they ... More
Spooky Action at No Distance: On the individuation of quantum mechanical systemsMar 11 2016Recent experiments have perfectly verified the fact that quantum correlations between two entangled particles are stronger than any classical, local pre-quantum worldview allows. This is famously called the EPR paradox first conceived as a thought experiment ... More
The Logic of Experimental Tests, Particularly of Everettian Quantum TheoryAug 09 2015Jun 18 2016Claims that the standard methodology of scientific testing is inapplicable to Everettian quantum theory, and hence that the theory is untestable, are due to misconceptions about probability and about the logic of experimental testing. Refuting those claims ... More
Some cohomology of finite general linear groupsSep 13 2015We prove that the degree $r(2p-3)$ cohomology of any (untwisted) finite group of Lie type over $\mathbb{F}_{p^r}$, with coefficients in characteristic $p$, is nonzero as long as its Coxeter number is at most $p$. We do this by providing a simple explicit ... More
Tagset Design and Inflected LanguagesApr 03 1995Apr 04 1995An experiment designed to explore the relationship between tagging accuracy and the nature of the tagset is described, using corpora in English, French and Swedish. In particular, the question of internal versus external criteria for tagset design is ... More
Does Baum-Welch Re-estimation Help Taggers?Oct 21 1994Oct 24 1994In part of speech tagging by Hidden Markov Model, a statistical model is used to assign grammatical categories to words in a text. Early work in the field relied on a corpus which had been tagged by a human annotator to train the model. More recently, ... More
Incremental Interpretation of Categorial GrammarMar 14 1995The paper describes a parser for Categorial Grammar which provides fully word by word incremental interpretation. The parser does not require fragments of sentences to form constituents, and thereby avoids problems of spurious ambiguity. The paper includes ... More
Physics of the Bacon Internal Resonator BanjoJun 20 2016The internal resonator banjo, patented and first sold by Fred Bacon around 1906, remains something of a cult favorite and is still produced by some independent luthiers. According to enthusiasts, the characteristic design elements produce a sound that ... More
On J. C. C. Nitsche type inequality for annuli on Riemann surfacesApr 24 2012Apr 27 2012Assume that $(\mathcal{N},\hbar)$ and $(\mathcal{M},\wp)$ are two Riemann surfaces with conformal metrics $\hbar$ and $\wp$. We prove that if there is a harmonic homeomorphism between an annulus $\mathcal{A}\subset \mathcal{N}$ with a conformal modulus ... More
Harmonic mappings and distance functionNov 12 2010We prove the following theorem: every quasiconformal harmonic mapping between two plane domains with $C^{1,\alpha}$ ($\alpha<1$), respectively $C^{1,1}$ compact boundary is bi-Lipschitz. The distance function with respect to the boundary of the image ... More
On boundary correspondence of q.c. harmonic mappings between smooth Jordan domainsOct 26 2009A quantitative version of an inequality obtained in \cite[Theorem~2.1]{mathz} is given. More precisely, for normalized $K$ quasiconformal harmonic mappings of the unit disk onto a Jordan domain $\Omega\in C^{1,\mu} $ ($0<\mu\le 1$) we give an explicit ... More
Lipschitz spaces and harmonic mappingsJan 25 2009In \cite{kamz} the author proved that every quasiconformal harmonic mapping between two Jordan domains with $C^{1,\alpha}$, $0<\alpha\le 1$, boundary is bi-Lipschitz, providing that the domain is convex. In this paper we avoid the restriction of convexity. ... More
Superharmonicity of Logarithm of Jacobian of harmonic mappings between surfacesMar 21 2016We prove that the Logarithm of the Jacobian of a sense preserving harmonic mappings between surfaces is superharmonic, provided that the Gaussian curvature of the image domain is non-negative.
Muckenhoupt weights and Lindelöf theorem for harmonic mappingsOct 30 2014We extend the result of Lavrentiev which asserts that the harmonic measure and the arc-length measure are $A_\infty$ equivalent in a chord-arc Jordan domain. By using this result we extend the classical result of Lindel\"of to the class of quasiconformal ... More
Direct Analysis of Spectra of Type Ib SupernovaeJun 20 2001Synthetic spectra generated with the parameterized supernova synthetic-spectrum code SYNOW are compared to photospheric-phase spectra of Type Ib supernovae (SNe Ib). Although the synthetic spectra are based on many simplifying approximations, including ... More
Type Ia Supernovae: Toward the Standard Model?Dec 13 2000In this short review I suggest that recent developments support the conjecture that Type Ia supernovae (SNe Ia) are the complete disruptions of Chandrasekhar-mass carbon-oxygen white dwarfs in single-degenerate binary systems. The causes of the observational ... More
Solar and Extrasolar Planet TaxonomyAug 02 2013Oct 11 2014A mass-based definition for planets is proposed with dynamical circumstances and compositional characteristics used to define types of planets. Dynamical planet classes include Principal planets, Belt planets, Moons, and Rogue planets. Compositional classes ... More
Cosmological Questions for the European Southern Observatory Very Large TelescopeAug 12 1996The next decade promises an observational revolution which will change cosmology forever. The precise measurement of the angular anisotropy of the cosmic microwave background should specify to a few percent all of the parameters of the cosmological model ... More
Stabilizing and destabilizing Heegaard splittings of sufficiently complicated 3-manifoldsJan 17 2012Let M_1 and M_2 be compact, orientable 3-manifolds with incompressible boundary, and M the manifold obtained by gluing with a homeomorphism $\phi:\bdy M_1 \to \bdy M_2$. We analyze the relationship between the sets of low genus Heegaard splittings of ... More
Regular Labelings and Geometric StructuresJul 01 2010Three types of geometric structure---grid triangulations, rectangular subdivisions, and orthogonal polyhedra---can each be described combinatorially by a regular labeling: an assignment of colors and orientations to the edges of an associated maximal ... More
Optimally fast incremental Manhattan plane embedding and planar tight span constructionSep 10 2009Oct 28 2011We describe a data structure, a rectangular complex, that can be used to represent hyperconvex metric spaces that have the same topology (although not necessarily the same distance function) as subsets of the plane. We show how to use this data structure ... More
Upright-Quad Drawing of st-Planar Learning SpacesJul 20 2006We consider graph drawing algorithms for learning spaces, a type of st-oriented partial cube derived from antimatroids and used to model states of knowledge of students. We show how to draw any st-planar learning space so all internal faces are convex ... More
The lattice dimension of a graphFeb 13 2004We describe a polynomial time algorithm for, given an undirected graph G, finding the minimum dimension d such that G may be isometrically embedded into the d-dimensional integer lattice Z^d.
Treetopes and their GraphsOct 12 2015We define treetopes, a generalization of the three-dimensional roofless polyhedra (Halin graphs) to arbitrary dimensions. Like roofless polyhedra, treetopes have a designated base facet such that every face of dimension greater than one intersects the ... More
Diamond-Kite Adaptive Quadrilateral MeshingJul 21 2012Jan 08 2013We describe a family of quadrilateral meshes based on diamonds, rhombi with 60 and 120 degree angles, and kites with 60, 90, and 120 degree angles, that can be adapted to a local size function by local subdivision operations. Our meshes use a number of ... More
Solving Single-digit Sudoku SubproblemsFeb 23 2012Mar 04 2012We show that single-digit "Nishio" subproblems in nxn Sudoku puzzles may be solved in time o(2^n), faster than previous solutions such as the pattern overlay method. We also show that single-digit deduction in Sudoku is NP-hard.
Isometric Diamond SubgraphsJul 14 2008We describe polynomial time algorithms for determining whether an undirected graph may be embedded in a distance-preserving way into the hexagonal tiling of the plane, the diamond structure in three dimensions, or analogous structures in higher dimensions. ... More
Finding Large Clique Minors is HardJun 30 2008May 13 2009We prove that it is NP-complete, given a graph G and a parameter h, to determine whether G contains a complete graph K_h as a minor.
Setting Parameters by ExampleJul 02 1999We introduce a class of "inverse parametric optimization" problems, in which one is given both a parametric optimization problem and a desired optimal solution; the task is to determine parameter values that lead to the given solution. We describe algorithms ... More
Zero-temperature criticality in a simple glass modelAug 04 1999We introduce the strongly-interacting trap model, a version of Bouchaud's trap model for glasses [Bouchaud J-P 1992 {\em J. Phys. I France {\bf 2}} 1705]. At finite temperatures the model exhibits glassy relaxation over intermediate timeframes but reaches ... More
A stability criterion for two-fluid interfaces and applicationsMay 25 2010We derive here a new stability criterion for two-fluid interfaces. This criterion ensures the existence of "stable" local solutions that do no break down too fast due to Kelvin-Helmholtz instabilities. It can be seen both as a two-fluid generalization ... More
Progressive Temporal Window WideningApr 04 2016Jul 03 2016This paper introduces a scheme for data stream processing which is robust to batch duration. Streaming frameworks process streams in batches retrieved at fixed time intervals. In a common setting a pattern recognition algorithm is applied independently ... More
High-pT pi0 Production with Respect to the Reaction Plane Using the PHENIX Detector at RHICSep 13 2006The origin of the azimuthal anisotropy in particle yields at high pT (pT > 5 GeV/c) in RHIC collisions remains an intriguing puzzle. Traditional flow and parton energy loss models have failed to completely explain the large v2 observed at high pT. Measurement ... More
High-pT Particle Production with Respect to the Reaction PlaneJul 10 2006The PHENIX Run4 data-set provides a powerful opportunity for exploring the angular anisotropy of identified particle yields at high pT. Complementing traditional v2 measurements, we present pi0 yields as a function of emission angle with respect to the ... More
PHENIX Results on Jet Correlations versus Reaction PlaneAug 04 2008In relativistic heavy-ion collisions, studying jet correlations and their dependence on the angle of emission with respect to the reaction plane can be used to shed light on the path length dependence of the energy lost by the jet. In this paper, we present ... More
Statistical Mechanics of systems with long range interactionsNov 19 2008Recent theoretical studies of statistical mechanical properties of systems with long range interactions are briefly reviewed. In these systems the interaction potential decays with a rate slower than 1/r^d at large distances r in d dimensions. As a result, ... More
A Review of the Current Status of Follow-Up Techniques to Study Known Extrasolar PlanetsDec 10 2003I present a review of observational efforts to study known extrasolar planets by methods that are complementary to the radial velocity technique. I describe the current state of attempts to detect and characterize such planets by astrometry, by reflected ... More
Verifying whether One-Tape Non-Deterministic Turing Machines Run in Time $Cn+D$Dec 02 2013May 19 2014We discuss the following family of problems, parameterized by integers $C\geq 2$ and $D\geq 1$: Does a given one-tape non-deterministic $q$-state Turing machine make at most $Cn+D$ steps on all computations on all inputs of length $n$, for all $n$? Assuming ... More
The t-Analogs of q-Characters at Roots of Unity for Quantum Affine Algebras and BeyoundMay 26 2003Apr 22 2004The q-characters were introduced by Frenkel and mReshetikhin to study finite dimensional representations of the untwisted quantum affine algebra for q generic. The $\epsilon$-characters at roots of unity were constructed by Frenkel and Mukhin to study ... More
Delayed Afterglow Onset Interpreted as Baryon-Poor Viewing AngleMar 24 2005We have suggested previously that baryons in GRB fireballs infiltrate from the surrounding walls that collimate the fireball. The efficiency $\epsilon_b$ for generating blast energy can then be angle dependent. Delayed onset of afterglow can be interpreted ... More
Discrete Ambiguities in B-Decay CP Asymmetries and the Search for New PhysicsMar 08 2000The first measurements of CP violation in the B system will probably extract $\sin 2\alpha$, $\sin 2\beta$ and $\cos 2\gamma$. Assuming that the CP angles $\alpha$, $\beta$ and $\gamma$ are the interior angles of the unitarity triangle, this determines ... More
Exotic FermionsMar 22 1993I review the current limits on the mixing of ordinary and exotic fermions.
B Physics: Theory OverviewJul 19 2012Jul 23 2012This is an overview of B physics that can be done at the LHC with the purpose of searching for new physics.
Geometric phases in adiabatic Floquet theory, abelian gerbes and Cheon's anholonomyMay 28 2009Jul 21 2009We study the geometric phase phenomenon in the context of the adiabatic Floquet theory (the so-called the $(t,t')$ Floquet theory). A double integration appears in the geometric phase formula because of the presence of two time variables within the theory. ... More
Non-negative Wigner functions in prime dimensionsJan 31 2007According to a classical result due to Hudson, the Wigner function of a pure, continuous variable quantum state is non-negative if and only if the state is Gaussian. We have proven an analogous statement for finite-dimensional quantum systems. In this ... More
Inflation and Kahler Stabilization of the DilatonFeb 04 2003The problems of attempting inflationary model-building in a theory containing a dilaton are explained. In particular, I study the shape of the dilaton potential today and during inflation, based on a weakly-coupled heterotic string model where corrections ... More
The Effect of Repeating Gamma Ray Bursts on V/VmaxDec 13 1993I consider the effect of repeating gamma ray burst sources on the <V/Vmax> statistic. I find that the treatment of repeating events, if applied consistently, will not affect the effectiveness of <V/Vmax> as a test of burst homogeneity. The calculation ... More
New Methods for Extracting the CKM Angle $γ$ using $B^\pm\to D^0 K^-$; $\bar D^0 K^-$Jul 03 1997In this talk I will discuss the extraction of the CKM angle $\gamma$ at B-factories through the interference of the subprocesses $B^-\to K^- D^0$ and $B^- \to K^-\bar D^0$. This seemingly impossible interference may be accomplished by allowing both $D^0$ ... More
Bath optimization in the Cellular Dynamical Mean Field TheoryMay 10 2010In the Cellular Dynamical Mean Field Theory (CDMFT), a strongly correlated system is represented by a small cluster of correlated sites, coupled to an adjustable bath of uncorrelated sites simulating the cluster's environment; the parameters governing ... More
Primordial perturbations from inflationJan 31 2002I review the standard analysis of adiabatic scalar and tensor perturbations produced by slow-roll inflation driven by a single scalar field, before going on to discuss recent work on the role of non-adiabatic modes during and after inflation. Isocurvature ... More
Local non-Gaussianity from inflationApr 06 2010The non-Gaussian distribution of primordial perturbations has the potential to reveal the physical processes at work in the very early Universe. Local models provide a well-defined class of non-Gaussian distributions that arise naturally from the non-linear ... More
Extended Gravity Theories and the Einstein-Hilbert ActionJul 23 1993I discuss the relation between arbitrarily high-order theories of gravity and scalar-tensor gravity at the level of the field equations and the action. I show that $(2n+4)$-order gravity is dynamically equivalent to Brans-Dicke gravity with an interaction ... More
Undesirable effects of covariance matrix techniques for error analysisMay 17 1993Sep 16 1993Regression with $\chi^2$ constructed from the covariance matrix should not be used for some combinations of covariance matrices and fitting functions. Using the technique for unsuitable combinations can amplify systematic errors. This amplification is ... More
The high-frequency finite-temperature quark dispersion relationOct 07 1993I calculate the dispersion relation for quarks of mass $m$ and momentum $k$ in a quark gluon plasma at temperature $T$, in the limit $m^2+k^2 \gg (gT)^2$, where $g$ is the strong coupling constant. I find three contributions to the dispersion relation: ... More
Three-Dimensional Gauge Theories and ADE MonopolesMar 18 1998We study three-dimensional N=4 gauge theories with product gauge groups constructed from ADE Dynkin diagrams. One-loop corrections to the metric on the Coulomb branch are shown to coincide with the metric on the moduli space of well-seperated ADE monopoles. ... More
Finite complex reflection arrangements are K(pi,1)Oct 26 2006Jan 22 2014Let $V$ be a finite dimensional complex vector space and $W\subseteq \GL(V)$ be a finite complex reflection group. Let $V^{\reg}$ be the complement in $V$ of the reflecting hyperplanes. We prove that $V^{\reg}$ is a $K(\pi,1)$ space. This was predicted ... More
Internally heated convection and Rayleigh-Bénard convectionJun 04 2015Nov 19 2015This work reviews basic features of both Rayleigh-B\'enard (RB) convection and internally heated (IH) convection, along with findings on IH convection from laboratory experiments and numerical simulations. In the first chapter, six canonical models of ... More
Fusion in Fractional Level sl^(2)-Theories with k=-1/2Dec 14 2010Feb 28 2011The fusion rules of conformal field theories admitting an sl^(2)-symmetry at level k=-1/2 are studied. It is shown that the fusion closes on the set of irreducible highest weight modules and their images under spectral flow, but not when "highest weight" ... More
On the Percolation BCFT and the Crossing Probability of WattsAug 26 2008Oct 10 2008The logarithmic conformal field theory describing critical percolation is further explored using Watts' determination of the probability that there exists a cluster connecting both horizontal and vertical edges. The boundary condition changing operator ... More
Optimal and Efficient Decoding of Concatenated Quantum Block CodesJun 14 2006Apr 04 2007We consider the problem of optimally decoding a quantum error correction code -- that is to find the optimal recovery procedure given the outcomes of partial "check" measurements on the system. In general, this problem is NP-hard. However, we demonstrate ... More
Toy Model for a Relational Formulation of Quantum TheoryMay 11 2005Jul 07 2005In the absence of an external frame of reference physical degrees of freedom must describe relations between systems. Using a simple model, we investigate how such a relational quantum theory naturally arises by promoting reference systems to the status ... More
Stabilizer Formalism for Operator Quantum Error CorrectionAug 18 2005Jun 14 2006Operator quantum error correction is a recently developed theory that provides a generalized framework for active error correction and passive error avoiding schemes. In this paper, we describe these codes in the stabilizer formalism of standard quantum ... More
Characterising cosmic inhomogeneity with anomalous diffusionOct 15 2014Jun 26 2015Dark matter (DM) clustering at the present epoch is investigated from a fractal viewpoint in order to determine the scale where the self-similar scaling property of the DM halo distribution transits to homogeneity. Methods based on well-established `counts-in-cells' ... More