Results for "Chris Holmes"

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Scalable Bayesian nonparametric regression via a Plackett-Luce model for conditional ranksJun 24 2015We present a novel Bayesian nonparametric regression model for covariates X and continuous, real response variable Y. The model is parametrized in terms of marginal distributions for Y and X and a regression function which tunes the stochastic ordering ... More
Supervised variable selection in randomised controlled trials prior to exploration of treatment effect heterogeneity: an example from severe malariaJan 11 2019Exploration of treatment effect heterogeneity (TEH) is an increasingly important aspect of modern statistical analysis for stratified medicine in randomised controlled trials (RCTs) as we start to gather more information on trial participants and wish ... More
Encrypted accelerated least squares regressionMar 02 2017Information that is stored in an encrypted format is, by definition, usually not amenable to statistical analysis or machine learning methods. In this paper we present detailed analysis of coordinate and accelerated gradient descent algorithms which are ... More
Bayesian Sparsity-Path-Analysis of Genetic Association Signal using Generalized t PriorsJun 01 2011We explore the use of generalized t priors on regression coefficients to help understand the nature of association signal within "hit regions" of genome-wide association studies. The particular generalized t distribution we adopt is a Student distribution ... More
A Hierarchical Bayesian Framework for Constructing Sparsity-inducing PriorsSep 09 2010Sep 16 2010Variable selection techniques have become increasingly popular amongst statisticians due to an increased number of regression and classification applications involving high-dimensional data where we expect some predictors to be unimportant. In this context, ... More
A Bayesian nonparametric approach to testing for dependence between random variablesJun 02 2015May 12 2016Nonparametric and nonlinear measures of statistical dependence between pairs of random variables are important tools in modern data analysis. In particular the emergence of large data sets can now support the relaxation of linearity assumptions implicit ... More
Approximate Models and Robust DecisionsFeb 25 2014Mar 06 2015Decisions based partly or solely on predictions from probabilistic models may be sensitive to model misspecification. Statisticians are taught from an early stage that "all models are wrong", but little formal guidance exists on how to assess the impact ... More
Assigning a value to a power likelihood in a general Bayesian modelJan 30 2017Bayesian approaches to data analysis and machine learning are widespread and popular as they provide intuitive yet rigorous axioms for learning from data; see Bernardo and Smith (2004) and Bishop (2006). However, this rigour comes with a caveat that the ... More
A Néron model of the universal jacobianDec 06 2014Sep 07 2015The jacobian of the universal curve over $\mathcal{M}_{g,n}$ is an abelian scheme over $\mathcal{M}_{g,n}$. Our main result is the construction of an algebraic space $\beta\colon \tilde{\mathcal{M}}_{g,n} \rightarrow \bar{\mathcal{M}}_{g,n}$ over which ... More
The Coherent Crooks EqualityDec 26 2018This chapter reviews an information theoretic approach to deriving quantum fluctuation theorems. When a thermal system is driven from equilibrium, random quantities of work are required or produced: the Crooks equality is a classical fluctuation theorem ... More
Torsion points and height jumping in higher-dimensional families of abelian varietiesApr 15 2016In 1983 Silverman and Tate showed that the set of points in a 1-dimensional family of abelian varieties where a section of infinite order has `small height' is finite. We conjecture a generalisation to higher-dimensional families, where we replace `finite' ... More
Generalized Bayesian Updating and the Loss-Likelihood BootstrapSep 22 2017In this paper, we revisit the weighted likelihood bootstrap and show that it is well-motivated for Bayesian inference under misspecified models. We extend the underlying idea to a wider family of inferential problems. This allows us to calibrate an analogue ... More
On Markov chain Monte Carlo methods for tall dataMay 11 2015Markov chain Monte Carlo methods are often deemed too computationally intensive to be of any practical use for big data applications, and in particular for inference on datasets containing a large number $n$ of individual data points, also known as tall ... More
A General Framework for Updating Belief DistributionsJun 27 2013Jan 28 2016We propose a framework for general Bayesian inference. We argue that a valid update of a prior belief distribution to a posterior can be made for parameters which are connected to observations through a loss function rather than the traditional likelihood ... More
Scalable Nonparametric Sampling from Multimodal Posteriors with the Posterior BootstrapFeb 08 2019Increasingly complex datasets pose a number of challenges for Bayesian inference. Conventional posterior sampling based on Markov chain Monte Carlo can be too computationally intensive, is serial in nature and mixes poorly between posterior modes. Further, ... More
A Framework for Adaptive MCMC Targeting Multimodal DistributionsDec 06 2018Jan 11 2019We propose a new Monte Carlo method for sampling from multimodal distributions. The idea of this technique is based on splitting the task into two: finding the modes of a target distribution $\pi$ and sampling, given the knowledge of the locations of ... More
General Bayesian Updating and the Loss-Likelihood BootstrapSep 22 2017May 22 2018In this paper we revisit the weighted likelihood bootstrap, a method that generates samples from an approximate Bayesian posterior of a parametric model. We show that the same method can be derived, without approximation, under a Bayesian nonparametric ... More
Multiscale Blind Source SeparationAug 25 2016We provide a new methodology for statistical recovery of single linear mixtures of piecewise constant signals (sources) with unknown mixing weights and change points in a multiscale fashion. We show exact recovery within an $\epsilon$-neighborhood of ... More
Principles of Bayesian Inference using General Divergence CriteriaFeb 26 2018May 17 2018When it is acknowledged that all candidate parameterised statistical models are misspecified relative to the data generating process, the decision maker (DM) must currently concern themselves with inference for the parameter value minimising the KL-divergence ... More
Characterising variation of nonparametric random probability measures using the Kullback-Leibler divergenceNov 24 2014This work studies the variation in Kullback-Leibler divergence between random draws from some popular nonparametric processes and their baseline measure. In particular we focus on the Dirichlet process, the P\'olya tree and the frequentist and Bayesian ... More
Encrypted statistical machine learning: new privacy preserving methodsAug 27 2015We present two new statistical machine learning methods designed to learn on fully homomorphic encrypted (FHE) data. The introduction of FHE schemes following Gentry (2009) opens up the prospect of privacy preserving statistical machine learning analysis ... More
Scalable Bayesian nonparametric measures for exploring pairwise dependence via Dirichlet Process MixturesApr 27 2016In this article we propose novel Bayesian nonparametric methods using Dirichlet Process Mixture (DPM) models for detecting pairwise dependence between random variables while accounting for uncertainty in the form of the underlying distributions. A key ... More
An efficient, nonlinear stability analysis for detecting pattern formation in reaction diffusion systemsJun 10 2012May 22 2013Reaction diffusion systems are often used to study pattern formation in biological systems. However, most methods for understanding their behavior are challenging and can rarely be applied to complex systems common in biological applications. I present ... More
Bayesian Boolean Matrix FactorisationFeb 20 2017Feb 25 2017Boolean matrix factorisation aims to decompose a binary data matrix into an approximate Boolean product of two low rank, binary matrices: one containing meaningful patterns, the other quantifying how the observations can be expressed as a combination ... More
Fields of definition of curves of a given degreeJan 31 2019Kontsevich and Manin gave a formula for the number $N_e$ of rational plane curves of degree $e$ through $3e-1$ points in general position in the plane. When these $3e-1$ points have coordinates in the rational numbers, the corresponding set of $N_e$ rational ... More
Obstacle problems generated by the estimates of square functionSep 17 2018In this note we give the formula for the Bellman function associated with the problem considered by B. Davis in \cite{Davis} in 1976. In this article the estimates of the type $\|Sf\|_p \le C_p \|f\|_p$, $p\ge 2$, were considered for the dyadic square ... More
Relating land use and human intra-city mobilityMay 27 2015Sep 20 2015Understanding human mobility patterns -- how people move in their everyday lives -- is an interdisciplinary research field. It is a question with roots back to the 19th century that has been dramatically revitalized with the recent increase in data availability. ... More
Biased random walk on the trace of biased random walk on the trace of...Jan 15 2019We study the behaviour of a sequence of biased random walks X(i), i>=0 on a sequence of random graphs, where the initial graph is Zd and otherwise the graph for the i-th walk is the trace of the (i - 1)-st walk. The sequence of bias vectors is chosen ... More
Population-Based Reversible Jump Markov Chain Monte CarloNov 01 2007In this paper we present an extension of population-based Markov chain Monte Carlo (MCMC) to the trans-dimensional case. One of the main challenges in MCMC-based inference is that of simulating from high and trans-dimensional target measures. In such ... More
A review of homomorphic encryption and software tools for encrypted statistical machine learningAug 26 2015Recent advances in cryptography promise to enable secure statistical computation on encrypted data, whereby a limited set of operations can be carried out without the need to first decrypt. We review these homomorphic encryption schemes in a manner accessible ... More
Semi-unsupervised Learning of Human Activity using Deep Generative ModelsOct 29 2018Dec 11 2018We introduce 'semi-unsupervised learning', a problem regime related to transfer learning and zero-shot learning where, in the training data, some classes are sparsely labelled and others entirely unlabelled. Models able to learn from training data of ... More
A System of Dependent Types, with an Implementation and a PhilosophyJul 06 2016This is my working paper on a proposed logical framework for the practice of mathematics, which is paralleled by philosophical considerations and a computer implementation (a variant of Automath).
Free energy of singular sticky-sphere clustersMay 27 2016Aug 16 2016Networks of particles connected by springs model many condensed-matter systems, from colloids interacting with a short-range potential, to complex fluids near jamming, to self-assembled lattices, to origami-inspired materials. Under small thermal fluctuations ... More
Generic transversality for unbranched covers of closed pseudoholomorphic curvesJul 02 2014Dec 12 2014We prove that in closed almost complex manifolds of any dimension, generic perturbations of the almost complex structure suffice to achieve transversality for all unbranched multiple covers of simple pseudoholomorphic curves with deformation index zero. ... More
Better together? Statistical learning in models made of modulesAug 29 2017In modern applications, statisticians are faced with integrating heterogeneous data modalities relevant for an inference, prediction, or decision problem. In such circumstances, it is convenient to use a graphical model to represent the statistical dependencies, ... More
Two-sample Bayesian Nonparametric Hypothesis TestingOct 27 2009May 11 2015In this article we describe Bayesian nonparametric procedures for two-sample hypothesis testing. Namely, given two sets of samples $\mathbf{y}^{\scriptscriptstyle(1)}\;$\stackrel{\scriptscriptstyle{iid}}{\s im}$\;F^{\scriptscriptstyle(1)}$ and $\mathbf{y}^{\scriptscriptstyle(2 ... More
Safe, Aggressive Quadrotor Flight via Reachability-based Trajectory DesignApr 11 2019Quadrotors can provide services such as infrastructure inspection and search-and-rescue, which require operating autonomously in cluttered environments. Autonomy is typically achieved with receding-horizon planning, where a short plan is executed while ... More
On the functor l^2Dec 21 2010Jul 29 2015We study the functor l^2 from the category of partial injections to the category of Hilbert spaces. The former category is finitely accessible, and in both categories homsets are algebraic domains. The functor preserves daggers, monoidal structures, enrichment, ... More
Complementarity in categorical quantum mechanicsSep 10 2010Mar 01 2016We relate notions of complementarity in three layers of quantum mechanics: (i) von Neumann algebras, (ii) Hilbert spaces, and (iii) orthomodular lattices. Taking a more general categorical perspective of which the above are instances, we consider dagger ... More
Evidence for a hard equation of state in the cores of neutron starsDec 19 2008The equation of state for matter with energy density above 2 x10^14 g/cm^3 is parametrized by P = kN^Gamma, where N is the number density, Gamma is the adiabatic index, and k a constant. Using this scheme to generate thousands of models, together with ... More
DIS and BeyondAug 30 2013A digest of my closing overview talk at DIS2013
Observational characteristics of accretion onto black holesAug 13 2010These notes resulted from a series of lectures at the IAC winter school. They are designed to help students, especially those just starting in subject, to get hold of the fundamental tools used to study accretion powered sources. As such, the references ... More
The origin of the soft excess in high L/L_Edd AGNMar 16 2007We discuss the origin of the soft X-ray excess seen in AGN. There are clear advantages to models where this arises from atomic processes in partially ionised material rather than where it is a true continuum component. However, current data cannot distinguish ... More
A short note on Simulation and AbstractionSep 20 2013This short note is written in celebration of David Schmidt's sixtieth birthday. He has now been active in the program analysis research community for over thirty years and we have enjoyed many interactions with him. His work on characterising simulations ... More
Implementation of classical communication in a quantum worldJun 19 2012Dec 18 2012Observations of quantum systems carried out by finite observers who subsequently communicate their results using classical data structures can be described as "local operations, classical communication" (LOCC) observations. The implementation of LOCC ... More
Consistent quantum mechanics admits no mereotopologyMay 13 2012Dec 09 2012It is standardly assumed in discussions of quantum theory that physical systems can be regarded as having well-defined Hilbert spaces. It is shown here that a Hilbert space can be consistently partitioned only if its components are assumed not to interact. ... More
If physics is an information science, what is an observer?Aug 24 2011Feb 11 2012Interpretations of quantum theory have traditionally assumed a "Galilean" observer, a bare "point of view" implemented physically by a quantum system. This paper investigates the consequences of replacing such an informationally-impoverished observer ... More
Autonomy all the way down: Systems and dynamics in quantum BayesianismAug 09 2011Apr 07 2012Quantum Bayesianism ("QBism") has been put forward as an approach to quantum theory that avoids foundational problems by altogether disavowing the objective existence of quantum states. It is shown that QBism suffers its own versions of the familiar foundational ... More
On the Ollivier-Poulin-Zurek definition of objectivityFeb 14 2011Jun 25 2013The Ollivier-Poulin-Zurek definition of objectivity provides a philosophical basis for the environment as witness formulation of decoherence theory and hence for quantum Darwinism. It is shown that no account of the reference of the key terms in this ... More
Information contents and architectural requirements of observer "ready" statesAug 09 2009Mar 05 2011A functional analysis of the task of observing multiple macroscopic quantum systems over an extended period of time and then reporting the accumulated results is used to investigate the information that must be encoded in the "ready" state |O^r> of any ... More
A sharp bilinear estimate for the Klein-Gordon equation in arbitrary space-time dimensionsFeb 21 2013We prove a sharp bilinear inequality for the Klein-Gordon equation on $\sr^{d+1}$, for any $d \geq 2$. This extends work of Ozawa-Rogers and Quilodr\'an for the Klein-Gordon equation and generalises work of Bez-Rogers for the wave equation. As a consequence ... More
Particle Physics: Themes and ChallengesNov 28 1995Opening Lecture at the Second Rencontres du Vietnam, October 21-28, 1995.
Ramification of Compatible Systems on Curves and Independence of $\ell$Jun 12 2014Oct 02 2014We show that certain ramification invariants associated to a compatible system of $\ell$-adic sheaves on a curve are independent of $\ell$.
Coupled one-dimensional dynamical systemsJan 19 2012This note aims to bring attention to a simple class of discrete dynamical systems exhibiting some complex behaviour. Each of these systems is defined as a self-mapping of the unit square and is obtained by coupling two families of self-mappings of the ... More
Some Notes on Standard Borel and Related SpacesSep 18 2008These notes give an elementary approach to parts of the theory of standard Borel and analytic spaces.
A new form of the Kerr solutionOct 27 1999Jan 31 2000A new form of the Kerr solution is presented. The solution involves a time coordinate which represents the local proper time for free-falling observers on a set of simple trajectories. Many physical phenomena are particularly clear when related to this ... More
Periodic GraphsJun 12 2008Oct 15 2010Let $X$ be a graph on $n$ vertices with with adjacency matrix $A$ and let $H(t)$ denote the matrix-valued function $\exp(iAt)$. If $u$ and $v$ are distinct vertices in $X$, we say perfect state transfer}from $u$ to $v$ occurs if there is a time $\tau$ ... More
Locally Cartesian Closed Quasicategories from Type TheoryJul 09 2015We prove that the quasicategories arising from models of Martin-L\"of type theory via simplicial localization are locally cartesian closed.
Business Models for e-Health: Evidence from Ten Case StudiesJul 02 2015An increasingly aging population and spiraling healthcare costs have made the search for financially viable healthcare models an imperative of this century. The careful and creative application of information technology can play a significant role in ... More
Probing Light Dark Matter via Evaporation from the SunJun 13 2015Dark matter particles can be captured by the sun with rates that depend on the dark matter mass and the DM-nucleon cross section. However, for masses below $\sim 3.3$ GeV, the captured dark matter particles evaporate, leading to an equilibrium where the ... More
Recent Results from (Full) Lattice QCDMay 04 2000An overview of the Lattice technique for studies of the strong interaction is given. Recent results from the UKQCD lattice collaboration are presented. These concentrate on spectral quantities calculated using full (i.e. unquenched) QCD. A comparison ... More
Quantum Darwinism requires an extra-theoretical assumption of encoding redundancyMar 26 2010May 30 2010Observers restricted to the observation of pointer states of apparatus cannot conclusively demonstrate that the pointer of an apparatus A registers the state of a system of interest S without perturbing S. Observers cannot, therefore, conclusively demonstrate ... More
Decompositional equivalenceApr 12 2010Apr 21 2010Both classical and quantum mechanics assume that physical laws are invariant under changes in the way that the world is labeled. This Principle of Decompositional Equivalence is formalized, and shown to forbid finite experimental demonstrations that given ... More
Three consequences of decompositional consistencyJun 12 2009Decompositions of the world into systems have typically been regarded as arbitrary extra-theoretical assumptions in discussions of quantum measurement. One can instead regard decompositions as part of the theory, and ask what conditions they must satisfy ... More
A Brief Summary of the Group-Variation EquationsApr 29 2001A brief summary is given of the Group-Variation Equations and the island diagram confinement mechanism, with an explanation of the prediction that the cylinder-topology minimal-area spanning surface term in the correlation function of two Wilson loops ... More
Eigenvalues of the static, spherically-symmetric Einstein-Proca equationsSep 20 2016The Proca potential has been used in many contexts in flat spacetime, but not so often in curved spacetime. Here, the static Proca potentials are derived on a Schwarzschild background, and are found to have very different forms from those in flat space. ... More
Roulettes: A weak lensing formalism for strong lensing - I. OverviewMar 15 2016Jul 26 2016We present a new perspective on gravitational lensing. We describe a new extension of the weak lensing formalism capable of describing strongly lensed images. By integrating the non-linear geodesic deviation equation, the amplification matrix of weak ... More
Cosmological Perturbation Theory as a Tool for Estimating Box-Scale Effects in N-body SimulationsDec 17 2013Jun 16 2014In performing cosmological N-body simulations, it is widely appreciated that the growth of structure on the largest scales within a simulation box will be inhibited by the finite size of the simulation volume. Following ideas set forth in Seto (1999), ... More
Localised Solutions of the Maxwell-Dirac EquationsOct 11 1995The full ``classical" Dirac-Maxwell equations are considered under various simplifying assumptions. A reduction of the equations is performed in the case when the Dirac field is {\em static} and a further reduction is performed in the case of {\em spherical ... More
Glueballs, hybrid and exotic mesons and string breakingSep 11 2000We review lattice QCD results for glueballs (including a discussion of mixing with scalar mesons), hybrid mesons and exotic mesons (such as $B_s B_s$ molecules). We also discuss string breaking as a mixing between colour flux states and $B \bar{B}$ states. ... More
Hadronic decays from the latticeSep 06 2006I review the lattice QCD approach to determining hadronic decay transitions. Examples considered include rho to pi pi; b_1 to pi omega; hybrid meson decays and scalar meson decays. I discuss what lattices can provide to help understand the composition ... More
Lifestyle Tradeoffs and the Decline of Societal Well-being: An Agent-based ModelJul 20 2015Jan 01 2016This paper presents a semi-quantitative mathematical model of the changes over time in the statistical distribution of well-being of individuals in a society. The model predicts that when individuals overvalue the more socially conspicuous aspects of ... More
On the functor l^2Dec 21 2010Sep 18 2018We study the functor l^2 from the category of partial injections to the category of Hilbert spaces. The former category is finitely accessible, and its homsets are algebraic domains; the latter category has conditionally algebraic domains for homsets. ... More
Lectures on Symplectic Field TheoryDec 03 2016Dec 08 2016This is the preliminary manuscript of a book on symplectic field theory based on a lecture course for PhD students given in 2015-16. It covers the essentials of the analytical theory of punctured pseudoholomorphic curves, taking the opportunity to fill ... More
A description of the Parry-Sullivan number of a graph using circuitsMar 11 2009In this short note, we give a description of the Parry-Sullivan number of a graph in terms of the cycles in the graph. This tool is occasionally useful in reasoning about the Parry-Sullivan numbers of graphs.
Reversible Markov chains: variational representations and orderingSep 06 2018This pedagogical document explains three variational representations that are useful when comparing the efficiencies of reversible Markov chains: (i) the Dirichlet form and the associated variational representations of the spectral gaps; (ii) a variational ... More
Locally Cartesian Closed Quasicategories from Type TheoryJul 09 2015Sep 17 2017We prove that the quasicategories arising from models of Martin-L\"of type theory via simplicial localization are locally cartesian closed.
A comparison of box and Carleson conditions on bi-treesMar 06 2019Mar 18 2019In this note we give an example of measure satisfying the box condition on certain sub-bi-trees (see below) but not satisfying Carleson condition on those sub-bi-trees. This can be considered as a certain counterexample for two weight bi-parameter embedding ... More
The Density Variance Mach Number Relation in the Taurus Molecular CloudFeb 05 2010Supersonic turbulence in molecular clouds is a key agent in generating density enhancements that may subsequently go on to form stars. The stronger the turbulence - the higher the Mach number - the more extreme the density fluctuations are expected to ... More
Learning and Complexity in Genetic Auto-Adaptive SystemsJan 27 1994We describe and investigate the learning capablities displayed by a population of self-replicating segments of computer-code subject to random mutation: the tierra environment. We find that learning is achieved through phase transitions that adapt the ... More
Semisymmetric cubic graphs of twice odd orderAug 09 2004The groups which can act semisymmetrically on a cubic graph of twice odd order are determined modulo a normal subgroup which acts semiregularly on the vertices of the graph.
Leptophobic U(1)'s and R_b, R_c at LEPJun 20 1996In the context of explaining the experimental deviations in R_b and R_c from their Standard Model predictions, a new type of U(1) interaction is proposed which couples only to quarks. Special attention will be paid to the supersymmetric \eta-model coming ... More
Decompositional equivalence: A fundamental symmetry underlying quantum theoryFeb 26 2014Apr 28 2016Decompositional equivalence is the principle that there is no preferred decomposition of the universe into subsystems. It is shown here, by using simple thought experiments, that quantum theory follows from decompositional equivalence together with Landauer's ... More
Finite Sets and CountingAug 31 2008Jun 19 2010We start by presenting a theory of finite sets using the approach which is essentially that taken by Whitehead and Russell in Principia Mathematica}, and which does not involve the natural numbers (or any other infinite set). This theory is then applied ... More
Robust String Matching in O(\sqrt{N}+M) Quantum QueriesNov 07 2003Aug 10 2004This paper was withdrawn by the author due to a fatal error.
Quantum Circuit IdentitiesJul 16 2003There are quantum circuit identities that simplify quantum circuits, reducing the effort needed physically to implement them. This paper constructs all identities made from 3 or fewer operations taken from a common set of one qubit operations, and explains ... More
The Hidden Subgroup Problem - Review and Open ProblemsNov 04 2004An overview of quantum computing and in particular the Hidden Subgroup Problem are presented from a mathematical viewpoint. Detailed proofs are supplied for many important results from the literature, and notation is unified, making it easier to absorb ... More
Yet More Projective Curves Over F2May 31 2001All binary plane curves of degree less than 7 are examined for curves with a large number of Fq rational points on their smooth model, for q = 2^m ; m = 3, 4,...,11. Previous results are improved, and many new curves are found meeting or close to Serre's, ... More
An open image theorem for a general class of abelian varietiesMar 11 2008Let K be a number field and A/K be a polarized abelian variety with absolutely trivial endomorphism ring. We show that if the Neron model of A/K has at least one fiber with potential toric dimension one, then for almost all rational primes ell, the Galois ... More
Average mixing of continuous quantum walksMar 14 2011Oct 01 2011If $X$ is a graph with adjacency matrix $A$, then we define $H(t)$ to be the operator $\exp(itA)$. The Schur (or entrywise) product $H(t)\circ H(-t)$ is a doubly stochastic matrix and, because of work related to quantum computing, we are concerned the ... More
Particle Physics after the Higgs-Boson Discovery: Opportunities for the Large Hadron ColliderJul 10 2015Aug 26 2015The first run of the Large Hadron Collider at CERN brought the discovery of the Higgs boson, an apparently elementary scalar particle with a mass of 125 GeV, the avatar of the mechanism that hides the electroweak symmetry. A new round of experimentation ... More
Building the Observer into the System: Toward a Realistic Description of Human Interaction with the WorldNov 13 2014Nov 10 2016Human beings do not observe the world from the outside, but rather are fully embedded in it. The sciences, however, often give the observer both a "god's eye" perspective and substantial a~priori knowledge. Motivated by W. Ross Ashby's statement, "the ... More
The general theory of secondary weak gravitational lensingMar 30 2015Weak gravitational lensing is normally assumed to have only two principle effects: a magnification of a source and a distortion of the sources shape in the form of a shear. However, further distortions are actually present owing to changes in the gravitational ... More
The many classical faces of quantum structuresDec 05 2014Mar 25 2015Interpretational problems with quantum mechanics can be phrased precisely by only talking about empirically accessible information. This prompts a mathematical reformulation of quantum mechanics in terms of classical mechanics. We survey this programme ... More
d = 11 Supergravity on almost flat R^4 times a compact hyperbolic 7-manifold, and the dip and bump seen in ATLAS-CONF-2010-088Mar 14 2011Jul 11 2011Rough estimates are presented to show that the bump at 1.7 to 1.9 TeV seen in ATLAS-CONF-2010-088 could arise from about 10^{30} approximately degenerate Kaluza-Klein states of the d = 11 supergravity multiplet in the s channel, that could arise from ... More
Natural TeV-Scale Gravity and coupling constant unification, in Heterotic M-Theory, with the usual hidden and visible sectors swappedJan 15 2002I consider a class of Grand Unified models, in which E8 is broken to SU(3)xSU(2)xSU(2)xSU(2)xU(1)_Y, then to SU(3)xSU(2)_{diag}xU(1)_Y. The breaking of (SU(2))^3 to SU(2)_{diag} reduces the SU(2) coupling constant, at unification, by a factor of 1/\sqrt{3}, ... More
What can the outskirts of galaxies tell us about dark matter?Aug 17 2016Deep observations of galaxy outskirts reveal faint extended stellar components (ESCs) of streams, shells, and halos, which are ghostly remnants of the tidal disruption of satellite galaxies. We use cosmological galaxy formation simulations in Cold Dark ... More
Roulettes: A weak lensing formalism for strong lensing - II. Derivation and analysisMar 15 2016Nov 14 2016We present a new extension of the weak lensing formalism capable of describing strongly lensed images. This paper accompanies Paper I, arXiv:1603.04698 where we provided a condensed overview of the approach and illustrated how it works. Here we give all ... More
Electromagnetic Energy Momentum Tensor in a Spatially Dispersive MediumFeb 24 2016We derive a generalized Minkowski Energy Momentum Tensor for a monochromatic wave in a lossless medium exhibiting temporal and spatial dispersion. The Energy Momentum Tensor is then related to familiar expressions for energy density and energy flux, as ... More
$P$-adic $L$-functions of Bianchi modular formsApr 08 2014Jan 22 2015The theory of overconvergent modular symbols, developed by Rob Pollack and Glenn Stevens, gives a beautiful and effective construction of the $p$-adic $L$-function of a modular form. In this paper, we give an analogue of their results for Bianchi modular ... More