Results for "Ian Walker"

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Geodesic Rosen continued fractionsOct 06 2013Apr 21 2015We describe how to represent Rosen continued fractions by paths in a class of graphs that arise naturally in hyperbolic geometry. This representation gives insight into Rosen's original work about words in Hecke groups, and it also helps us to identify ... More
Graph Convolutional Gaussian ProcessesMay 14 2019We propose a novel Bayesian nonparametric method to learn translation-invariant relationships on non-Euclidean domains. The resulting graph convolutional Gaussian processes can be applied to problems in machine learning for which the input observations ... More
Even-integer continued fractions and the Farey treeAug 06 2015Singerman introduced to the theory of maps on surfaces an object that is a universal cover for any map. This object is a tessellation of the hyperbolic plane together with a certain subset of the ideal boundary. The 1-skeleton of this tessellation comprises ... More
Semi-Supervised Learning via Compact Latent Space ClusteringJun 07 2018Jul 29 2018We present a novel cost function for semi-supervised learning of neural networks that encourages compact clustering of the latent space to facilitate separation. The key idea is to dynamically create a graph over embeddings of labeled and unlabeled samples ... More
Handling an uncertain control group event risk in non-inferiority trials: non-inferiority frontiers and the power-stabilising transformationMay 01 2019Background. Non-inferiority (NI) trials are increasingly used to evaluate new treatments expected to have secondary advantages over standard of care, but similar efficacy on the primary outcome. When designing a NI trial with a binary primary outcome, ... More
Controlling Meshes via Curvature: Spin Transformations for Pose-Invariant Shape ProcessingMar 06 2019We investigate discrete spin transformations, a geometric framework to manipulate surface meshes by controlling mean curvature. Applications include surface fairing -- flowing a mesh onto say, a reference sphere -- and mesh extrusion -- e.g., rebuilding ... More
Thermodynamics of a Simple Three-Dimensional DNA Hairpin ModelJun 23 2016We characterize the equation of state for a simple three-dimensional DNA hairpin model using a Metropolis Monte Carlo algorithm. This algorithm was run at constant temperature and fixed separation between the terminal ends of the strand. From the equation ... More
Bigraphical NetsFeb 26 2013Interaction nets are a graphical model of computation, which has been used to define efficient evaluators for functional calculi, and specifically lambda calculi with patterns. However, the flat structure of interaction nets forces pattern matching and ... More
Detection of a population of carbon-enhanced metal-poor stars in the Sculptor dwarf spheroidal galaxyMar 12 2018Apr 25 2018The study of the chemical abundances of metal-poor stars in dwarf galaxies provides a venue to constrain paradigms of chemical enrichment and galaxy formation. Here we present metallicity and carbon abundance measurements of 100 stars in Sculptor from ... More
Detailed Chemical Abundances in the r-Process-Rich Ultra-Faint Dwarf Galaxy Reticulum 2Jan 15 2016The ultra-faint dwarf galaxy Reticulum 2 (Ret 2) was recently discovered in images obtained by the Dark Energy Survey. We have observed the four brightest red giants in Ret 2 at high spectral resolution using the Michigan/Magellan Fiber System. We present ... More
Yoneda structures and KZ doctrinesMar 25 2017Aug 09 2017In this paper we strengthen the relationship between Yoneda structures and KZ doctrines by showing that for any locally fully faithful KZ doctrine, with the notion of admissibility as defined by Bunge and Funk, all of the Yoneda structure axioms apart ... More
Stable immersions in orbifoldsDec 10 2013Aug 21 2014We prove that in any hyperbolic orbifold with one boundary component, the product of any hyperbolic fundamental group element with a sufficiently large multiple of the boundary is represented by a geodesic loop that virtually bounds an immersed surface. ... More
Coefficient growth in square chainsFeb 27 2019Suppose $((\cdots((x^{2}-c_{1})^{2}-c_{2})^{2}\cdots)^{2}-c_{k-1})^{2}-c_{k}$ splits into linear factors over $\mathbb{Z}$ and $c_{k}\neq0$. We show that for each $j$ and each prime $p$, if $p\leq2^{j-1}$ then $p$ divides $c_{j}$. Consequently, $$\ln ... More
Gowers norms control diophantine inequalitiesMar 02 2017Nov 03 2018A central tool in the study of systems of linear equations with integer coefficients is the Generalised von Neumann Theorem of Green and Tao. This theorem reduces the task of counting the weighted solutions of these equations to that of counting the weighted ... More
Universal properties of bicategories of polynomialsJun 27 2018Dec 23 2018We establish the universal properties of the bicategory of polynomials, considering both cartesian and general morphisms between these polynomials. A direct proof of these universal properties would be impractical due to the complicated coherence conditions ... More
New approaches to Bayesian consistencyMar 29 2005We use martingales to study Bayesian consistency. We derive sufficient conditions for both Hellinger and Kullback-Leibler consistency, which do not rely on the use of a sieve. Alternative sufficient conditions for Hellinger consistency are also found ... More
Global Bifurcation of Positive Equilibria in Nonlinear Population ModelsJul 07 2009Existence of nontrivial nonnegative equilibrium solutions for age structured population models with nonlinear diffusion is investigated. Introducing a parameter measuring the intensity of the fertility, global bifurcation is shown of a branch of positive ... More
Stable commutator length in free products of cyclic groupsApr 23 2013We give an algorithm to compute stable commutator length in free products of cyclic groups which is polynomial time in the length of the input, the number of factors, and the orders of the finite factors. We also describe some experimental and theoretical ... More
An elementary view of familial pseudofunctorsDec 23 2018Mar 16 2019A classical result due to Diers shows that a presheaf $F\colon\mathcal{A}\to\mathbf{Set}$ on a category $\mathcal{A}$ is a coproduct of representables precisely when each connected component of $F$'s category of elements has an initial object. Most often, ... More
An Energy Minimization Approach to 3D Non-Rigid Deformable Surface Estimation Using RGBD DataAug 02 2017We propose an algorithm that uses energy mini- mization to estimate the current configuration of a non-rigid object. Our approach utilizes an RGBD image to calculate corresponding SURF features, depth, and boundary informa- tion. We do not use predetermined ... More
Quantifying the Fragility of Galactic Disks in Minor MergersOct 09 1995We perform fully self-consistent stellar dynamical simulations of the accretion of a companion ("satellite") galaxy by a large disk galaxy to investigate the interaction between the disk, halo, and satellite components of the system during a merger. Our ... More
Center of Gravity-based Approach for Modeling Dynamics of Multisection Continuum ArmsJan 06 2019Multisection continuum arms offer complementary characteristics to those of traditional rigid-bodied robots. Inspired by biological appendages, such as elephant trunks and octopus arms, these robots trade rigidity for compliance, accuracy for safety, ... More
A Mobile Robotic Personal Nightstand with Integrated Perceptual ProcessesOct 13 2013We present an intelligent interactive nightstand mounted on a mobile robot, to aid the elderly in their homes using physical, tactile and visual percepts. We show the integration of three different sensing modalities for controlling the navigation of ... More
Moments of L'(1/2) in the Family of Quadratic TwistsAug 20 2012Nov 12 2012We prove the asymptotic formulae for several moments of derivatives of GL(2) L-functions over quadratic twists. The family of L-functions we consider has root number fixed to -1 and odd orthogonal symmetry. Assuming GRH we prove the asymptotic formulae ... More
Computer Network Defense Through Radial Wave FunctionsOct 06 2016The purpose of this research was to synthesize basic and fundamental findings in quantum computing, as applied to the attack and defense of conventional computer networks. The concept focuses on uses of radio waves as a shield for, and attack against ... More
Axial compression of a thin elastic cylinder: bounds on the minimum energy scaling lawApr 28 2016May 10 2016We consider the axial compression of a thin elastic cylinder placed about a hard cylindrical core. Treating the core as an obstacle, we prove upper and lower bounds on the minimum energy of the cylinder that depend on its relative thickness and the magnitude ... More
Nielsen equivalence in mapping tori over the torusOct 24 2016We use the geometry of the Farey graph to give an alternative proof of the fact that if $A \in GL_2\mathbb Z$ and $G_A=\mathbb Z^2 \rtimes_A \mathbb Z$ is generated by two elements, there is a single Nielsen equivalence class of $2$-element generating ... More
A graph TQFT for hat Heegaard Floer homologyMar 19 2015Apr 02 2015In this paper we introduce an extension of the hat Heegaard Floer TQFT which allows cobordisms with disconnected ends. Our construction goes by way of sutured Floer homology, and uses some elementary results from contact geometry. We provide some model ... More
Revisiting 154-day periodicity in the occurrence of hard flares. A planetary influence?Nov 14 2016Rieger et al (1984) reported observations of a 154 day periodicity in flares during solar cycle 21. This paper discusses the observations in the light of a simple empirical planetary model of sunspot emergence. The planetary model predicts sunspot emergence ... More
Lower bounds on volumes of hyperbolic Haken 3-manifoldsJun 27 1999In this paper, we find lower bounds for volumes of hyperbolic 3-manifolds with various topological conditions. Let V_3 = 1.01494 denote the volume of a regular ideal simplex in hyperbolic 3-space. As a special case of the main theorem, if a hyperbolic ... More
Thermodynamic cycle in a cavity optomechanical systemFeb 16 2014A cavity optomechanical system is initiated by a radiation pressure of a cavity field onto a mirror element acting as a quantum resonator. This radiation pressure can control the thermodynamic character of the mirror to some extent, such as cooling its ... More
Quasi-lattice chains and multipartite entanglement in a cavityJun 12 2013Nov 12 2014Unlike atoms in a lattice, the spacings between neighboring qubits in a superconducting quantum circuit are mesoscopic and non-uniform. The strength of interaction between this quasi-lattice chain of qubits and a resonator mode in circuit transmission ... More
Edge Critical Behaviour of the 2-Dimensional Tri-critical Ising ModelMay 17 2000Using previous results from boundary conformal field theory and integrability, a phase diagram is derived for the 2 dimensional Ising model at its bulk tri-critical point as a function of boundary magnetic field and boundary spin-coupling constant. A ... More
Luttinger liquid parameter for the spin-1 Heisenberg chain in a magnetic fieldAug 15 2005A recently derived general formula and older numerical results are combined to deduce the behavior of the transverse correlation exponent for the spin-1 Heisenberg antiferromagnetic chain in an applied magnetic field: eta = 1/2 - (2.0)m +O(m^2), where ... More
Conformal Field Theory Approach to Quantum Impurity ProblemsNov 23 1993Nov 27 1993A brief review is given of a new method for studying the critical behavior of quantum impurity problems, based on conformal field theory techniques, which I developed with Andreas Ludwig. Some results on the overscreened Kondo problem are reviewed. It ... More
Conformal Field Theory Approach to the Kondo EffectDec 12 1995Recently, a new approach, based on boundary conformal field theory, has been applied to a variety of quantum impurity problems in condensed matter and particle physics. A particularly enlightening example is the multi-channel Kondo problem. In this review ... More
Generalized five-dimensional Kepler system, Yang-Coulomb monopole and Hurwitz transformationSep 21 2011Mar 25 2012The 5D Kepler system possesses many interesting properties. This system is superintegrable and also with a $su(2)$ nonAbelian monopole interaction (Yang-Coulomb monopole). This system is also related to a 8D isotropic harmonic oscillator by a Hurwitz ... More
Polynomial Associative Algebras for Quantum Superintegrable Systems with a Third Order Integral of MotionJan 26 2007We consider a superintegrable Hamiltonian system in a two-dimensional space with a scalar potential that allows one quadratic and one cubic integral of motion. We construct the most general associative cubic algebra and we present specific realizations. ... More
Quartic Poisson algebras and quartic associative algebras and realizations as deformed oscillator algebrasApr 26 2013We introduce the most general quartic Poisson algebra generated by a second and a fourth order integral of motion of a 2D superintegrable classical system. We obtain the corresponding quartic (associative) algebra for the quantum analog and we extend ... More
Cosmological and Astrophysical Constraints on Tensor UnparticlesOct 23 2007We calculate cosmological and astrophysical bounds on the couplings between standard model fields and tensor unparticles. The present day density of tensor unparticles from neutrino-neutrino and photon-photon annihilation is calculated. Also, the supernovae ... More
The Weyl law for algebraic toriAug 29 2018We give an asymptotic evaluation for the number of automorphic characters of an algebraic torus $T$ with bounded analytic conductor. The analytic conductor which we use is defined via the local Langlands correspondence for tori by choosing a finite dimensional ... More
Nielsen equivalence in mapping tori over the torusOct 24 2016Jul 24 2017We use the geometry of the Farey graph to give an alternative proof of the fact that if $A \in GL_2\mathbb Z$ and $G_A=\mathbb Z^2 \rtimes_A \mathbb Z$ is generated by two elements, there is a single Nielsen equivalence class of $2$-element generating ... More
GIT Constructions of Moduli Spaces of Stable Curves and MapsOct 14 2008This largely expository paper first gives an introduction to Hilbert stability and its use in Gieseker's GIT construction of $\overline{M}_g$. Then I review recent work in this area--variants for unpointed curves that arise in Hassett's log minimal model ... More
Higher order superintegrability, Painlevé transcendents and representations of polynomial algebrasApr 26 2019In recent years, progress toward the classification of superintegrable systems with higher order integrals of motion has been made. In particular, a complete classification of all exotic potentials with a third or a fourth order integrals, and allowing ... More
Use of Taus in ATLASOct 24 2002At the LHC, new particles can be expected that decay to final states involving taus. Examples are given from simulations by the ATLAS experiment showing how such final states can be exploited.
Bounds on exceptional Dehn filling IIMar 20 2008We show that there are at most finitely many one cusped orientable hyperbolic 3-manifolds which have more than eight non-hyperbolic Dehn fillings. Moreover, we show that determining these finitely many manifolds is decidable.
Pants immersed in hyperbolic 3-manifoldsFeb 19 2008We show that an immersed thrice-punctured sphere in a cusped orientable hyperbolic 3-manifold is either embedded or has a single clasp in a manifold obtained by hyperbolic Dehn filling on a cusp of the Whitehead link complement.
The Social Architecture of CapitalismJan 06 2004Mar 23 2011A dynamic model of the social relations between workers and capitalists is introduced. The model is deduced from the assumption that the law of value is an organising principle of modern economies. The model self-organises into a dynamic equilibrium with ... More
The duration of recessions follows an exponential not a power lawNov 25 2003Mar 23 2011Ormerod and Mounfield analysed GDP data of 17 leading capitalist economies from 1870 to 1994 and concluded that the frequency of the duration of recessions is consistent with a power-law. But in fact the data is consistent with an exponential (Boltzmann-Gibbs) ... More
The Kondo screening cloud: what it is and how to observe itNov 11 2009Jan 08 2010The Kondo effect involves the formation of a spin singlet by a magnetic impurity and conduction electrons. It is characterized by a low temperature scale, the Kondo temperature, $T_K$, and an associated long length scale, $\xi_K = \hbar v_F/(k_BT_K)$ ... More
Edge Magnetic Field in the xxz Spin-1/2 ChainOct 21 1997Feb 12 1998The critical behavior associated with a transverse magnetic field applied at the edge of a semi-infinite xxz S=1/2 chain is calculated using field theory techniques. Contrary to a recent claim, we find that the long-time behavior is given by a renormalization ... More
Boundary Condition Changing Operators in Conformal Field Theory and Condensed Matter PhysicsNov 09 1996Boundary condition changing operators in conformal field theory describe various types of "sudden switching" problems in condensed matter physics such as the X-ray edge singularity. We review this subject and give two extensions of previous work. A general ... More
Generalized MICZ-Kepler system, duality, polynomial and deformed oscillator algebrasApr 26 2010Aug 27 2010We present the quadratic algebra of the generalized MICZ-Kepler system in three-dimensional Euclidean space $E_{3}$ and its dual the four dimensional singular oscillator in four-dimensional Euclidean space $E_{4}$. We present their realization in terms ... More
Generalized Kaluza-Klein monopole, quadratic algebras and ladder operatorsMar 02 2011We present a generalized Kaluza-Klein monopole system. We solve this quantum superintegrable systems on a Euclidean Taub Nut manifold using the separation of variables of the corresponding Schroedinger equation in spherical and parabolic coordinates. ... More
Geometry and Rank of Fibered Hyperbolic 3-ManifoldsMar 08 2008Assume that M is a closed hyperbolic 3-manifold fibering over the circle with fiber a closed orientable surface of genus g. We show that if M has large diameter and its injectivity radius is bounded below, then the rank of the fundamental group of M is ... More
Evidence of two different types of short term solar modulation of regional surface temperature and cloudJan 22 2014Recent work indicates that 27 day variations in cosmic ray flux during 2007 2009 are phase locked to 27 day variations in cloud and surface temperature at Shetland. Here we extend the study to other regions including Central England, US and Australia ... More
Cross-Polarized Microwave Surface-State Anti-ResonanceOct 22 2013Jul 14 2014We propose a polarization-sensitive measurement of microwave electromagnetic resonances in a magnetic field to detect the metallic surface state of a bulk insulator. A quantitative model is used to demonstrate that a unique, unambiguous signature of the ... More
Introduction to Spin-Polarized Ballistic Hot Electron Injection and Detection in SiliconOct 14 2009Ballistic hot electron transport overcomes the well-known problems of conductivity and spin lifetime mismatch that plagues spin injection in semiconductors with ferromagnetic ohmic contacts. Through the spin-dependent mean-free-path, it also provides ... More
Human-Machine Symbiosis, 50 Years OnDec 13 2007Licklider advocated in 1960 the construction of computers capable of working symbiotically with humans to address problems not easily addressed by humans working alone. Since that time, many of the advances that he envisioned have been achieved, yet the ... More
Special Lagrangian cones in C^3 and primitive harmonic mapsJan 17 2002Jul 02 2002In this article I show that every special Lagrangian cone in C^3 determines, and is determined by, a primitive harmonic surface in the 6-symmetric space SU_3/SO_2. For cones over tori, this allows us to use the classification theory of harmonic tori to ... More
Factorization and high-energy effective actionDec 10 1998I demonstrate that the amplitude for high-energy scattering can be factorized as a convolution of the contributions due to fast and slow fields. The fast and slow fields interact by means of Wilson-line operators -- infinite gauge factors ordered along ... More
Mellin representation of the graviton bulk-to-bulk propagator in AdSFeb 02 2011A Mellin-type representation of the graviton bulk-to-bulk propagator from Ref. 1 in terms of the integral over the product of bulk-to-boundary propagators is derived.
Effective field theory for the small-x evolutionMay 31 2001The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is ... More
Operator Expansion for Diffractive High-Energy ScatteringJun 18 1997I discuss the operator expansion for diffractive high-energy scattering and present the non-linear evolution equation for the relevant Wilson-line operators which describes both the propagator of the BFKL pomeron and the three-pomeron vertex.
T Parity and the Littlest HiggsSep 02 2004Sep 10 2004We construct T-parity invariant extensions of the littlest Higgs model, in which only linear representations of the full symmetry group are employed, without recourse to the non-linear representations introduced by Coleman, Callan, Wess, and Zumino (CCWZ). ... More
Model Independent Extractions of |V_{ub}| from Inclusive B DecaysSep 15 2000We discuss the possibility of extracting |V_{ub}| from various spectra of inclusive B decays, without large systematic errors which usually arise from having to model the Fermi motion of the heavy quark. This strategy can be applied to the electron energy ... More
Polarized Charginos (and Tops) in Stop DecaysApr 01 2013Mar 31 2014Current searches for direct production of scalar top quarks, or stops, in supersymmetry focus on their decays into W boson + b quark + neutralino by way of top + neutralino and bottom + chargino. While the polarization of the top quark depends on the ... More
MIMO Z Channel Interference ManagementMar 31 2012MIMO Z Channel is investigated in this paper. We focus on how to tackle the interference when different users try to send their codewords to their corresponding receivers while only one user will cause interference to the other. We assume there are two ... More
Soliton Confinement and the Excitation Spectrum of Spin-Peierls AntiferromagnetsMay 14 1997The excitation spectrum of spin-Peierls antiferromagnets is discussed taking into acount phonon dynamics but treating inter-chain elastic couplings in mean field theory. This gives a ladder of soliton -anti-soliton boundstates, with no soliton continuum, ... More
Classical ladder operators, polynomial Poisson algebras and classification of superintegrable systemsSep 21 2011Mar 19 2012We recall results concerning one-dimensional classical and quantum systems with ladder operators. We obtain the most general one-dimensional classical systems respectively with a third and a fourth order ladder operators satisfying polynomial Heisenberg ... More
An infinite family of superintegrable systems from higher order ladder operators and supersymmetryAug 18 2010Dec 23 2010We will discuss how we can obtain new quantum superintegrable Hamiltonians allowing the separation of variables in Cartesian coordinates with higher order integrals of motion from ladder operators. We will discuss also how higher order supersymmetric ... More
A Perfect Set of Reals with Finite Self-InformationOct 29 2012We examine a definition of the mutual information of two reals proposed by Levin. The mutual information is I(X:Y)=log(sum(2^{K(s)-K^X(s)+K(t)-K^Y(t)-K(s,t)}, (s,t) pairs of finite binary strings), where K is the prefix-free Kolmogorov complexity. A real ... More
Modular non-repeating codes for DNA storageJun 06 2016Jun 08 2016We describe a strategy for constructing codes for DNA-based information storage by serial composition of weighted finite-state transducers. The resulting state machines can integrate correction of substitution errors; synchronization by interleaving watermark ... More
Sacks of dice with fair totalsNov 09 2014A fair sack is a finite set of independent dice, not required to be fair and allowed to have any number of sides, for which all totals are equally likely. These have been studied for over 60 years. Most results restrict the possible orders of dice in ... More
Decay of correlations for slowly mixing flowsNov 06 2006We show that polynomial decay of correlations is prevalent for a class of nonuniformly hyperbolic flows. These flows are the continuous time analogue of a class of nonuniformly hyperbolic diffeomorphisms for which Young proved polynomial decay of correlations. ... More
Tangency bifurcation of invariant manifolds in a slow-fast systemDec 15 2015We study a three-dimensional dynamical system in two slow variables and one fast variable. We analyze the tangency of the unstable manifold of an equilibrium point with "the" repelling slow manifold, in the presence of a stable periodic orbit emerging ... More
New CleverHans Feature: Better Adversarial Robustness Evaluations with Attack BundlingNov 08 2018This technical report describes a new feature of the CleverHans library called "attack bundling". Many papers about adversarial examples present lists of error rates corresponding to different attack algorithms. A common approach is to take the maximum ... More
Generalized Weyl algebras: category O and graded Morita equivalenceApr 23 2009Nov 04 2009We study the structural and homological properties of graded Artinian modules over generalized Weyl algebras (GWAs), and this leads to a decomposition result for the category of graded Artinian modules. Then we define and examine a category of graded ... More
Graph cobordisms and Heegaard Floer homologyDec 03 2015May 10 2019We construct a graph TQFT for the minus flavor of Heegaard Floer homology. Our graph TQFT extends Ozsv\'{a}th and Szab\'{o}'s TQFT for closed and connected 3-manifolds, and allows for cobordisms with disconnected ends. As an application, we give an explicit ... More
Link cobordisms and absolute gradings on link Floer homologyJan 12 2017Oct 18 2018We show that the link cobordism maps defined by the author are graded and satisfy a grading change formula. Using the grading change formula, we prove a new bound for $\Upsilon_K(t)$ for knot cobordisms in negative definite 4-manifolds. As another application, ... More
On representation schemes and Grassmanians of finite dimensional algebras and a construction of LusztigNov 10 2009Sep 01 2010Let I be a finite set and CI be the algebra of functions on I. For a finite dimensional C algebra A with \CI contained in A we show that certain moduli spaces of finite dimsional modules are isomorphic to certain Grassmannian (quot-type) varieties. There ... More
Asymptotic stability of shear-flow solutions to incompressible viscous free boundary problems with and without surface tensionAug 07 2017This paper concerns the dynamics of a layer of incompressible viscous fluid lying above a rigid plane and with an upper boundary given by a free surface. The fluid is subject to a constant external force with a horizontal component, which arises in modeling ... More
Standing Ring Blowup Solutions for Cubic NLSFeb 05 2010Mar 07 2010We prove there exist solutions to the focusing cubic nonlinear Schr\"odinger equation in three dimensions that blowup on a circle, in the sense of L^2 concentration on a ring, bounded H^1 norm outside any surrounding toroid, and growth of the global H^1 ... More
The role of mutation rate variation and genetic diversity in the architecture of human diseaseAug 29 2013We have investigated the role that the mutation rate and the structure of genetic variation at a locus play in determining whether a gene is involved in disease. We predict that the mutation rate and its genetic diversity should be higher in genes associated ... More
Tunnel conductance spectroscopy via harmonic generation in a hybrid capacitor deviceMar 19 2013Jul 30 2013We address the measurement of density of states within and beyond the superconducting gap in tunnel-coupled finite-size nanostructures using a capacitive method. Third-harmonic generation is used to yield the full differential conductance spectrum without ... More
Summary talk: Gauge Boson Self InteractionsApr 03 1995A review is given of the theoretical expectations of the self couplings of gauge bosons and of the present experimental information on the couplings. The possibilities for future measurements are also discussed.
On the semi-annual, 27 day, variation in geomagnetic activity, cloud cover and surface temperatureDec 03 2013We develop a basic model of the time variation of geomagnetic activity and show that the model predicts, with decreasing levels of exactitude, the time variation of the ~27 day period components of geomagnetic aa index, cloud cover and surface temperature ... More
The evolvability of business and the role of antitrustMar 06 2012In this paper, based on theories of complex adaptive systems, I argue that the main case for antitrust policy should be extended to include the criteria of "evolvability." To date, the main case focuses on economizing, including market power as a key ... More
Multiple Dirichlet Series for Affine Weyl GroupsJun 03 2014Let $W$ be the Weyl group of a simply-laced affine Kac-Moody Lie group, excepting $\tilde{A}_n$ for $n$ even. We construct a multiple Dirichlet series $Z(x_1, \ldots x_{n+1})$, meromorphic in a half-space, satisfying a group $W$ of functional equations. ... More
NS-NS fluxes in Hitchin's generalized geometryDec 12 2006Dec 17 2007The standard notion of NS-NS 3-form flux is lifted to Hitchin's generalized geometry. This generalized flux is given in terms of an integral of a modified Nijenhuis operator over a generalized 3-cycle. Explicitly evaluating the generalized flux in a number ... More
Relating branes and matricesJan 12 2005We construct a general map between a Dp-brane with magnetic flux and a matrix configuration of D0-branes, by showing how one can rewrite the boundary state of the Dp-brane in terms of its D0-brane constituents. This map gives a simple prescription for ... More
AGN astrophysics from comparing radio and Gaia optical astrometryJan 29 2013Gaia will open up a huge volume of new parameter space in which to explore the physics of AGN and black hole evolution. We address the question as to how far along the relativistic jets blazar radio, optical and gamma ray emission originated. In some ... More
A conjecture on the distribution of firm profitJul 27 2004Mar 23 2011A common assumption of political economy is that profit rates across firms or sectors tend to uniformity, and often models are formulated in which this tendency is assumed to have been realised. But in reality this tendency is never realised and the distribution ... More
Singular Isotonic Oscillator, Supersymmetry and SuperintegrabilitySep 19 2012In the case of a one-dimensional nonsingular Hamiltonian $H$ and a singular supersymmetric partner $H_a$, the Darboux and factorization relations of supersymmetric quantum mechanics can be only formal relations. It was shown how we can construct an adequate ... More
Quadratic Algebra Approach to Relativistic Quantum Smorodinsky-Winternitz SystemsDec 08 2010Dec 23 2010There exist a relation between the Klein-Gordon and the Dirac equations with scalar and vector potentials of equal magnitude (SVPEM) and the Schrodinger equation. We obtain the relativistic energy spectrum for the four Smorodinsky-Winternitz systems from ... More
Evidence of a planetary influence on solar activity: Phase coherence of the variation in sunspot area with the tidal effect of MercuryOct 08 2015There have been numerous reports of quasiperiodicities in solar activity in the intermediate period range. However, no accepted explanation for the episodic occurrence of quasiperiodicities has emerged. This paper examines the possibility that the periodicities ... More
Metrizing the Chabauty topologyOct 24 2016Oct 25 2016We describe an explicit metric that induces the Chabauty topology on the space of closed subsets of a proper metric space M.
Double Soft Theorems and Shift Symmetry in Nonlinear Sigma ModelsDec 03 2015We show both the leading and subleading double soft theorems of the nonlinear sigma model follow from a shift symmetry enforcing Adler's zero condition in the presence of an unbroken global symmetry. They do not depend on the underlying coset G/H and ... More
Compiling Process Networks to Interaction NetsSep 13 2016Kahn process networks are a model of computation based on a collection of sequential, deterministic processes that communicate by sending messages through unbounded channels. They are well suited for modelling stream-based computations, but are in no ... More
A new model in the Calogero-Ruijsenaars familyNov 19 2013Dec 22 2013Hamiltonian reduction is used to project a trivially integrable system on the Heisenberg double of $SU(n,n)$, to obtain a system of Ruijsenaars type on a suitable quotient space. This system possesses $BC_n$ symmetry and is shown to be equivalent to the ... More