Results for "Ethan C. Jackson"

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Novelty Search for Deep Reinforcement Learning Policy Network Weights by Action Sequence Edit Metric DistanceFeb 08 2019Reinforcement learning (RL) problems often feature deceptive local optima, and learning methods that optimize purely for reward signal often fail to learn strategies for overcoming them. Deep neuroevolution and novelty search have been proposed as effective ... More
Limiting speed of a second class particle in ASEPMar 22 2019Mar 25 2019We study the asymptotic speed of a second class particle in the two-species asymmetric simple exclusion process (ASEP) on $\mathbb{Z}$ with each particle belonging either to the first class or the second class. For any fixed non-negative integer $L$, ... More
Nonmalleable Information Flow: Technical ReportAug 29 2017Aug 31 2017Noninterference is a popular semantic security condition because it offers strong end-to-end guarantees, it is inherently compositional, and it can be enforced using a simple security type system. Unfortunately, it is too restrictive for real systems. ... More
Magic polarization for light shift cancellation in two-photon optical clocksDec 27 2018May 29 2019We find a simple solution to the problem of probe laser light shifts in two-photon optical atomic clocks. We show that there exists a magic polarization at which the light shifts of the two atomic states involved in the clock transition are identical. ... More
Radically solvable graphsJul 06 2012A 2-dimensional framework is a straight line realisation of a graph in the Euclidean plane. It is radically solvable if the set of vertex coordinates is contained in a radical extension of the field of rationals extended by the squared edge lengths. We ... More
Cosmic evolution and unified models for radio AGNJul 30 1999A new method of deriving the cosmological evolution of radio AGN is described which is based on the premise of unified models for quasars and radio galaxies.
Behavioral Communities and the Atomic Structure of NetworksOct 12 2017We develop a theory of `behavioral communities' and the `atomic structure' of networks. We define atoms to be groups of agents whose behaviors always match each other in a set of coordination games played on the network. This provides a microfoundation ... More
A finite generating set for the genus g (p,q,n)-dipole series from perturbative Yang-Mills theoryOct 12 2011There is an emerging class of permutation factorization questions that cannot be expressed wholly in terms of the centre of the group algebra of the symmetric group. We shall term these non-central. A notable instance appears in recent work of Constable ... More
Testing models of radio source space density evolution with the SUMSS surveyAug 07 1998Aug 10 1998We present the population data as predicted by our space density analysis at the SUMSS frequency of 843 MHz. This data demonstrates the potential of the SUMSS survey to trace in detail the change-over in radio source populations from `radio monsters' ... More
The Redshift Distribution of Extragalactic Radio SourcesAug 25 1998Extragalactic radio sources are a unique cosmological probe in that they trace large-scale structure on scales inaccessible to other wavelengths. However as radio survey data is inherently 2D, the redshift distribution, N(z), is necessary to derive spatial ... More
Radio Galaxy SpectraJan 22 2001Radio spectra of radio galaxies are often ascribed a simple power law form ($S_{\nu} \propto \nu^{\alpha}$) with the spectral index, $\alpha$, being of order -0.7. However, all radio galaxies deviate from this simple power law behaviour. In this paper ... More
Extragalactic radio source evolution & unification: clues to the demographics of blazarsJan 23 2001In this paper we discuss the demographics of the radio blazar population: (i) what are their parent (`unbeamed') sources and (ii) what magnitude and/or type of evolution have they undergone ? The discussion is based on models of radio source evolution ... More
Extragalactic radio source evolution under the dual-population unification schemeAug 07 1998Nov 05 1998We show that a dual-population unification scheme provides a successful paradigm with which to describe the evolution and beaming of all bright extragalactic radio sources. The paradigm consists of two intrinsic radio-source populations, based on the ... More
Rational curves of degree 11 on a general quintic threefoldNov 17 2007Apr 02 2010We prove that the incidence scheme of rational curves of degree 11 on quintic threefolds is irreducible. This implies a strong form of the Clemens conjecture in degree 11. Namely, on a general quintic threefold $F$ in $\mathbb{P}^4$, there are only finitely ... More
Conjugacy in the Cantor Set Automorphism GroupJul 28 2019We survey, and extend, results on the adjoint action of the homeomorphism group $H(X)$ on the space of surjective continuous maps, $C_s(X)$, where $X$ is a Cantor set. We look also at the restriction of the action to various dynamically defined subsets ... More
The Integral Cohomology of the Bianchi GroupsSep 27 2002We calculate the integral cohomology ring structure for various members of the Bianchi group family. The main tools we use are the Bockstein spectral sequence and a long exact sequence derived from Bass-Serre theory.
Rock, Paper, Scissors, Etc - The Theory of Regular TournamentsJun 29 2018Apr 28 2019Following the extension of the classic Rock-Paper-Scissors game of size 3 to Rock-Paper-Scissors-Lizard-Spock of size 5, we consider further extensions to larger odd numbers. Such extensions are modeled by directed graphs called tournaments. The games ... More
Generalized Intransitive Dice: Mimicking an Arbitrary TournamentJan 28 2019Apr 28 2019A generalized $N$-sided die is a random variable $D$ on a sample space of $N$ equally likely outcomes taking values in the set of positive integers. We say of independent $N$ sided dice $D_i, D_j$ that $D_i$ beats $D_j$, written $D_i \to D_j$, if $Prob(D_i ... More
Geometry of curves with exceptional secant planes: linear series along the general curveJun 14 2007Apr 02 2010We study linear series on a general curve of genus $g$, whose images are exceptional with regard to their secant planes. Working in the framework of an extension of Brill-Noether theory to pairs of linear series, we prove that a general curve has no linear ... More
Skip-Thought Memory NetworksNov 19 2015Nov 24 2015Question Answering (QA) is fundamental to natural language processing in that most nlp problems can be phrased as QA (Kumar et al., 2015). Current weakly supervised memory network models that have been proposed so far struggle at answering questions that ... More
On the Generalizability of Linear and Non-Linear Region of Interest-Based Multivariate Regression Models for fMRI DataFeb 03 2018In contrast to conventional, univariate analysis, various types of multivariate analysis have been applied to functional magnetic resonance imaging (fMRI) data. In this paper, we compare two contemporary approaches for multivariate regression on task-based ... More
K2-146: Discovery of Planet c, Precise Masses from Transit Timing, and Observed PrecessionJul 24 2019K2-146 is a mid-M dwarf ($M_\star = 0.331 \pm 0.009 M_\odot$; $R_\star = 0.330 \pm 0.010 R_\odot$), observed in Campaigns 5, 16, and 18 of the K2 mission. In Campaign 5 data, a single planet was discovered with an orbital period of $2.6$~days and large ... More
A Module System for Domain-Specific LanguagesMay 16 2014Domain-specific languages (DSLs) are routinely created to simplify difficult or specialized programming tasks. They expose useful abstractions and design patterns in the form of language constructs, provide static semantics to eagerly detect misuse of ... More
Low-Frequency Measurements of Seismic Velocity and Attenuation in Antigorite SerpentiniteNov 16 2018Laboratory measurements of seismic velocity and attenuation in antigorite serpentinite at a confining pressure of $2$ kbar and temperatures up to $550^\circ$C (i.e., in the antigorite stability field) provide new results relevant to the interpretation ... More
Spontaneous DC Current Generation in a Resistively Shunted Semiconductor Superlattice Driven by a TeraHertz FieldSep 02 1997We study a resistively shunted semiconductor superlattice subject to a high-frequency electric field. Using a balance equation approach that incorporates the influence of the electric circuit, we determine numerically a range of amplitude and frequency ... More
Oort cloud asteroids: Collisional evolution, the Nice Model, and the Grand TackMar 07 2019If the Solar system had a history of planet migration, the signature of that migration may be imprinted on the populations of asteroids and comets that were scattered in the planets' wake. Here, we consider the dynamical and collisional evolution of inner ... More
$\bar{K} + N \to K + Ξ$ reaction and $S=-1$ hyperon resonancesMar 03 2015May 25 2015The $\bar{K} + N \to K + \Xi$ reaction is studied for center-of-momentum energies ranging from threshold to 3 GeV in an effective Lagrangian approach that includes the hyperon $s$- and $u$-channel contributions as well as a phenomenological contact amplitude. ... More
Jordan blocks of Richardson classes in the classical groups and the Bala--Carter TheoremAug 06 2003This paper provides new, relatively simple proofs of some important results about unipotent classes in simple linear algebraic groups. We derive the formula for the Jordan blocks of the Richardson class of a parabolic subgroup of a classical group. This ... More
Pathological phenomena in Denjoy-Carleman classesAug 18 2014Feb 26 2015Let $\mathcal C^M$ denote a Denjoy-Carleman class of $\mathcal C^\infty$ functions (for a given logarithmically-convex sequence $M = (M_n)$). We construct: (1) a function in $\mathcal C^M((-1,1))$ which is nowhere in any smaller class; (2) a function ... More
Is there a Ramsey-Hindman theorem ?Apr 01 2015Aug 21 2015We show that there does not exist a joint generalization of the theorems of Ramsey and Hindman, or more explicitly, that the property of containing a symmetric IP-set is not divisible.
An Empirical Analysis of the Python Package Index (PyPI)Jul 25 2019Jul 26 2019In this research, we provide a comprehensive empirical summary of the Python Package Repository, PyPI, including both package metadata and source code covering 178,592 packages, 1,745,744 releases, 76,997 contributors, and 156,816,750 import statements. ... More
Finite-temperature phase structure of SU(4) gauge theory with multiple fermion representationsFeb 26 2018We investigate the phase structure of SU(4) gauge theory with the gauge field simultaneously coupled to two flavors of fermion in the fundamental representation and two flavors of fermion in the two-index antisymmetric representation. We find that the ... More
Inertial-Range Reconnection in Magnetohydrodynamic Turbulence and in the Solar WindMar 02 2015In situ spacecraft data on the solar wind show events identified as magnetic reconnection with outflows and apparent "`$X$-lines" $10^{3-4}$ times ion scales. To understand the role of turbulence at these scales, we make a case study of an inertial-range ... More
Endomorphisms and automorphisms of minimal symbolic systems with sublinear complexityNov 29 2014We show that if the complexity difference function p(n+1)-p(n) of a infinite minimal shift is bounded, then the the automorphism group of the one-sided shift is finite, and the automorphism group of the corresponding two-sided shift "modulo the shift" ... More
Consistent estimates of deformed isotropic Gaussian random fields on the planeOct 01 2007Aug 21 2009This paper proves fixed domain asymptotic results for estimating a smooth invertible transformation $f:\Bbb{R}^2\to\Bbb{R}^2$ when observing the deformed random field $Z\circ f$ on a dense grid in a bounded, simply connected domain $\Omega$, where $Z$ ... More
WAP Systems and Labeled SubshiftsOct 17 2014Oct 31 2016The main object of this work is to present a powerful method of construction of subshifts which we use chiefly to construct WAP systems with various properties. Among many other applications of this so called labeled subshifts, we obtain examples of null ... More
Gravitational lenses and lens candidates identified from the COSMOS fieldJun 23 2008A complete manual search has been carried out of the list of 285423 objects, nearly all of them galaxies, identified in the COSMOS field that are brighter than I=25. Two certain and one highly probable new gravitational lenses are found, in addition to ... More
Quasar lensingApr 15 2013I review the observations of gravitationally lensed quasars. These systems are important because they allow us to probe the properties of the lensing galaxies at various scales, and they also allow insights into the structures of the quasars themselves. ... More
Infinite irredundant equational axiomatisability for a finite monoidNov 18 2015It is shown that a finite monoid can have an infinite irredundant basis of equations.
Re-Examination of Simple Kaluza-Klein CosmologiesJun 23 2018Simple cosmological models based upon five-dimensional Kaluza-Klein relativity are re-examined and interesting properties are indicated. These models are special cases of those obtained by Davidson et al. and Mann and Vincent, specifically, those with ... More
Reply to Comment on "Reevaluation of the parton distribution of strange quarks in the nucleon"Aug 17 2015Dec 02 2015A Comment on the recently published reevaluation of the polarization-averaged parton distribution of strange quarks in the nucleon using final data on the multiplicities of charged kaons in semi-inclusive deep-inelastic scattering is reviewed. Important ... More
The Hubble ConstantSep 25 2007Nov 20 2014I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual ... More
Liouville Brownian Motion and Thick Points of the Gaussian Free FieldDec 04 2014We find a lower bound for the Hausdorff dimension that a Liouville Brownian motion spends in $\alpha$-thick points of the Gaussian Free Field, where $\alpha$ is not necessarily equal to the parameter used in the construction of the geometry. This completes ... More
The Parkes quarter-Jansky flat-spectrum sample 2. New Optical Spectra and Redshift MeasurementsDec 17 2002We present optical spectra and redshift measurements for 178 flat-spectrum objects from the Parkes quarter-Jansky flat-spectrum sample. These spectra were obtained in order to compile a complete sample of quasars for use in a study of quasar evolution. ... More
HI Observations of the Local Group Dwarf WLMJul 06 2004We present Australia Telescope Compact Array mosaic HI imaging of the Local Group dwarf irregular galaxy WLM. We find an integrated flux of 149 Jy km/s and a total HI mass of 3.2 x 10^7 solar masses. The major axis of the HI is aligned with the stellar ... More
A Spitzer IRAC Census of the Asymptotic Giant Branch Populations in Local Group Dwarfs. II. IC 1613Jun 21 2007We present Spitzer Space Telescope IRAC photometry of the Local Group dwarf irregular galaxy IC 1613. We compare our 3.6, 4.5, 5.8, and 8.0 micron photometry with broadband optical photometry and find that the optical data do not detect 43% and misidentify ... More
Search for New Physics with Atoms and MoleculesOct 05 2017Jul 20 2018This article reviews recent developments in tests of fundamental physics using atoms and molecules, including the subjects of parity violation, searches for permanent electric dipole moments, tests of the CPT theorem and Lorentz symmetry, searches for ... More
Spatially Resolved PAH Emission Features in Nearby, Low Metallicity, Star-Forming GalaxiesSep 14 2010Low-resolution, mid-infrared Spitzer/IRS spectral maps are presented for three nearby, low-metallicity dwarf galaxies (NGC 55, NGC 3109 and IC 5152) for the purpose of examining the spatial distribution and variation of polycyclic aromatic hydrocarbon ... More
Anomalous Primes and the Elliptic Korselt CriterionAug 08 2016Aug 21 2018We explore the relationship between elliptic Korselt numbers of Type I, a class of pseudoprimes introduced by Silverman in [20], and anomalous primes. We generalize a result in [20] that gives sufficient conditions for an elliptic Korselt number of Type ... More
Vortices in Bose-Einstein Condensates: TheoryApr 02 2007Vortices are pervasive in nature, representing the breakdown of laminar fluid flow and hence playing a key role in turbulence. The fluid rotation associated with a vortex can be parameterized by the circulation $\Gamma=\oint {\rm d}{\bf r}\cdot{\bf v}({\bf ... More
Inflection divisors of linear series on an elliptic curveMar 07 2019Mar 25 2019In this largely-expository note, we describe a class of divisors on elliptic curves that index the inflection points of linear series arising (as subspaces of holomorphic sections) from line bundles on $\mathbb{P}^1$ via pullback along the canonical 2-to-1 ... More
Using a 3D printer for 2D beam profile measurements in proton radiotherapyAug 10 2019We have used an inexpensive 3D printer mounting an inexpensive pre-irradiated silicon diode to measure the 2D dose distribution of a small (approximately 10mm FWHM) proton beam. z was measured with high resolution whereas x was changed on a 2mm grid for ... More
EBIT Observation of Ar Dielectronic Recombination Lines Near the Unknown Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy ClustersFeb 04 2019Motivated by possible atomic origins of the unidentified emission line detected at 3.55 keV to 3.57 keV in a stacked spectrum of galaxy clusters (Bulbul et al. 2014), an electron beam ion trap (EBIT) was used to investigate the resonant dielectronic recombination ... More
Finite field elements of high order arising from modular curvesOct 12 2012In this paper, we recursively construct explicit elements of provably high order in finite fields. We do this using the recursive formulas developed by Elkies to describe explicit modular towers. In particular, we give two explicit constructions based ... More
Common Glass-Forming Spin-Liquid State in the Pyrochlore Magnets Dy$_2$Ti$_2$O$_7$ and Ho$_2$Ti$_2$O$_7$Jul 27 2017Nov 27 2018Despite a well-ordered pyrochlore crystal structure and strong magnetic interactions between the Dy$^{3+}$ or Ho$^{3+}$ ions, no long range magnetic order has been detected in the pyrochlore titanates Ho$_2$Ti$_2$O$_7$ and Dy$_2$Ti$_2$O$_7$. To explore ... More
Real inflection points of real linear series on an elliptic curveApr 18 2018Given a real elliptic curve $E$ with non-empty real part and $[D]\in \mbox{Pic}^2 E$ its $g_2^1$, we study the real inflection points of distinguished subseries of the complete real linear series $|\mathcal{L}_\mathbb{R}(kD)|$ for $k\geq 3$. We define ... More
Magnetic Helicity Conservation and Astrophysical DynamosOct 18 2000Dec 18 2000We construct a magnetic helicity conserving dynamo theory which incorporates a calculated magnetic helicity current. In this model the fluid helicity plays a small role in large scale magnetic field generation. Instead, the dynamo process is dominated ... More
The Generation of Magnetic Fields Through Driven TurbulenceMar 27 2000Jun 14 2000We have tested the ability of driven turbulence to generate magnetic field structure from a weak uniform field using three dimensional numerical simulations of incompressible turbulence. We used a pseudo-spectral code with a numerical resolution of up ... More
Adaptive spline fitting with particle swarm optimizationJul 28 2019Jul 30 2019In fitting data with a spline, finding the optimal placement of knots can significantly improve the quality of the fit. However, the challenging high-dimensional and non-convex optimization problem associated with completely free knot placement has been ... More
A Supercooled Spin Liquid State in the Frustrated Pyrochlore Dy2Ti2O7May 13 2015May 20 2015A "supercooled" liquid develops when a fluid does not crystallize upon cooling below its ordering temperature. Instead, the microscopic relaxation times diverge so rapidly that, upon further cooling, equilibration eventually becomes impossible and glass ... More
Using Ontologies To Improve Performance In Massively Multi-label Prediction ModelsMay 28 2019Massively multi-label prediction/classification problems arise in environments like health-care or biology where very precise predictions are useful. One challenge with massively multi-label problems is that there is often a long-tailed frequency distribution ... More
Lattice Diagrams of Knots and Diagrams of Lattice Stick KnotsMar 09 2018We give a simple example showing that a knot or link diagram that lies in the ${\mathbb{Z}}^2$ lattice is not necessarily the projection of a lattice stick knot or link in the ${\mathbb{Z}}^3$ lattice, and we give a necessary and sufficient condition ... More
Bayesian determination of the effect of a deep eutectic solvent on the structure of lipid monolayersOct 17 2018Feb 28 2019In this work, we present the first example of the self-assembly of phospholipid monolayers at the interface between air and an ionic solvent. Deep eutectic solvents are a novel class of environmentally friendly non-aqueous room temperature liquids with ... More
Calibration of the K-Profile Parameterization of ocean boundary layer mixing. Part I: DevelopmentApr 20 2016In model comparisons with observational data, not all data contain information that is useful for answering a specific science question. If non-relevant or highly uncertain data are included in a comparison metric, they can reduce the significance of ... More
Velocity-selective direct frequency-comb spectroscopy of atomic vaporsJun 05 2012We present an experimental and theoretical investigation of two-photon direct frequency-comb spectroscopy performed through velocity-selective excitation. In particular, we explore the effect of repetition rate on the $\textrm{5S}_{1/2}\rightarrow \textrm{5D}_{3/2, ... More
On Extending the Mass-Metallicity Relation of Galaxies by 2.5 Decades in Stellar MassMay 01 2006We report 4.5 micron luminosities for 27 nearby (D < 5 Mpc) dwarf irregular galaxies measured with the Spitzer Infrared Array Camera. We have constructed the 4.5 micron luminosity-metallicity (L-Z) relation for 25 dwarf galaxies with secure distance and ... More
Axiomatisability and hardness for universal Horn classes of hypergraphsApr 07 2017We characterise finite axiomatisability and intractability of deciding membership for universal Horn classes generated by finite loop-free hypergraphs.
What Syntactic Structures block Dependencies in RNN Language Models?May 24 2019Recurrent Neural Networks (RNNs) trained on a language modeling task have been shown to acquire a number of non-local grammatical dependencies with some success. Here, we provide new evidence that RNN language models are sensitive to hierarchical syntactic ... More
Smale Strategies For The N-Person Iterated Prisoner's DilemmaFeb 11 2018Adapting methods introduced by Steven Smale, we describe good strategies for a symmetric version of the Iterated Prisoner's Dilemma with n players.
MHD Turbulence: Scaling Laws and Astrophysical ImplicationsMay 17 2002Turbulence is the most common state of astrophysical flows. In typical astrophysical fluids, turbulence is accompanied by strong magnetic fields, which has a large impact on the dynamics of the turbulent cascade. Recently, there has been a significant ... More
Computing automorphism groups of shifts using atypical equivalence classesMay 11 2015Feb 01 2017We study the automorphism group of an infinite minimal shift $(X,\sigma)$ such that the complexity difference function, $p(n+1)-p(n)$, is bounded. We give some new bounds on $\mbox{Aut}(X,\sigma)/\langle \sigma \rangle$ and also study the one-sided case. ... More
$L(\mathbb{R})$ with Determinacy Satisfies the Suslin HypothesisMar 22 2018The Suslin hypothesis states that there are no nonseparable complete dense linear orderings without endpoints which have the countable chain condition. $\mathsf{ZF + AD^+ + V = L(\mathscr{P}(\mathbb{R}))}$ proves the Suslin hypothesis. In particular, ... More
Integrating out Heavy Fields in InflationMar 17 2012I present the procedure for integrating out quantum fields whose mass M is well above the Hubble scale H in de Sitter space. The effective interaction and density matrix are explicitly computed for a simple example and are found to be of order H/M, are ... More
The algebra of adjacency patterns: Rees matrix semigroups with reversionJul 15 2009We establish a surprisingly close relationship between universal Horn classes of directed graphs and varieties generated by so-called adjacency semigroups which are Rees matrix semigroups over the trivial group with the unary operation of reversion. In ... More
The Stability of Noncommutative Scalar SolitonsMar 26 2001Oct 03 2001We determine the stability conditions for a radially symmetric noncommutative scalar soliton at finite noncommutivity parameter $\theta$. We find an intriguing relationship between the stability and existence conditions for all level-1 solutions, in that ... More
Marathon Environments: Multi-Agent Continuous Control Benchmarks in a Modern Video Game EngineFeb 25 2019Recent advances in deep reinforcement learning in the paradigm of locomotion using continuous control have raised the interest of game makers for the potential of digital actors using active ragdoll. Currently, the available options to develop these ideas ... More
A new measure of treatment effect for random-effects meta-analysis of comparative binary outcome dataJun 09 2018Comparative binary outcome data are of fundamental interest in statistics and are often pooled in meta-analyses. Here we examine the simplest case where for each study there are two patient groups and a binary event of interest, giving rise to a series ... More
The Structure of Matter in Spacetime from the Substructure of TimeFeb 22 2018The nature of the change in perspective that accompanies the proposal of a unified physical theory deriving from the single dimension of time is elaborated. On expressing a temporal interval in a multi-dimensional form, via a direct arithmetic decomposition, ... More
A new distribution for robust least squaresAug 14 2014A new distribution is introduced, which we call the twin-t distribution. This distribution is heavy-tailed like the t distribution, but closer to normality in the central part of the curve. Its properties are described, e.g. the pdf, the distribution ... More
Generalised Proper Time as a Unifying Basis for Models with Two Right-Handed NeutrinosMay 27 2019Models with two right-handed neutrinos are able to accommodate solar and atmospheric neutrino oscillation observations as well as a mechanism for the baryon asymmetry of the universe. While economical in terms of the required new states beyond the Standard ... More
Domain and range for angelic and demonic compositionsOct 30 2018We give finite axiomatizations for the varieties generated by representable domain--range algebras when the semigroup operation is interpreted as angelic or demonic composition, respectively.
All or nothing: toward a promise problem dichotomy for constraint problemsNov 03 2016Apr 30 2017A finite constraint language $\mathscr{R}$ is a finite set of relations over some finite domain $A$. We show that intractability of the constraint satisfaction problem $\operatorname{CSP}(\mathscr{R})$ can, in all known cases, be replaced by an infinite ... More
Hermes and the spin of the protonAug 12 2002HERMES is a second generation experiment to study the spin structure of the nucleon, in which measurements of the spin dependent properties of semi-inclusive deep-inelastic lepton scattering are emphasized. Data have been accumulated for semi-inclusive ... More
Computer Generated Images for Quadratic Rational Maps with a Periodic Critical PointSep 17 2010We describe an algorithm for distinguishing hyperbolic components in the parameter space of quadratic rational maps with a periodic critical point. We then illustrate computer images of the hyperbolic components of the parameter spaces V1 - V4, which ... More
Subrings of $\mathbb{C}$ Generated by AnglesJan 02 2016Consider the following inductively defined set. Given a collection $U$ of unit magnitude complex numbers, and a set initially containing just 0 and 1, through each point in the set, draw lines whose angles with the real axis are in $U$. Add every intersection ... More
Transversity and Spin Structure FunctionsAug 24 2004Measurements of single-spin asymmetries for semi-inclusive electro-production of pions and kaons in deep-inelastic scattering with transverse target polarization open a new window on the transverse quark and gluon structure of the nucleon. The first experimental ... More
Meta-Fibonacci Sequences, Binary Trees, and Extremal Compact CodesApr 19 2005We look at a family of meta-Fibonacci sequences which arise in studying the number of leaves at the largest level in certain infinite sequences of binary trees, restricted compositions of an integer, and binary compact codes. For this family of meta-Fibonacci ... More
Non-archimedean entire curves in closed subvarieties of semi-abelian varietiesJul 30 2019We prove a non-archimedean analogue of the fact that a closed subvariety of a semi-abelian variety is hyperbolic modulo its special locus, and thereby generalize a result of Cherry.
Measurement of $ΔS$ in the nucleon at HERMES from semi-inclusive DISJan 03 2006Sep 13 2006The helicity distribution of the strange quark sea in the proton has been extracted from measurements of polarized production of charged kaons in deep-inelastic scattering from a polarized deuterium target.
Nuclear spin content and constraints on exotic spin-dependent couplingsJul 10 2014Apr 07 2015There are numerous recent and ongoing experiments employing a variety of atomic species to search for couplings of atomic spins to exotic fields. In order to meaningfully compare these experimental results, the coupling of the exotic field to the atomic ... More
Spatial pattern and power function deviation in a cellular automata model of an ant populationDec 29 2015A spatially explicit model previously developed to apply to a population of arboreal nesting ants in southern Mexico is explored in detail, including notions of criticality and robust criticality and expected power law adjustment.
From Unified Field Theory to the Standard Model and BeyondSep 12 2018One hundred years ago this year attempts began to generalise general relativity with the ambition of incorporating electromagnetism alongside gravitation in a unified field theory. These developments led to gauge theories and models with extra spatial ... More
Multi-Level Stochastic Gradient Methods for Nested Composition OptimizationJan 11 2018Jan 12 2018Stochastic gradient methods are scalable for solving large-scale optimization problems that involve empirical expectations of loss functions. Existing results mainly apply to optimization problems where the objectives are one- or two-level expectations. ... More
Accelerating Stochastic Composition OptimizationJul 25 2016Consider the stochastic composition optimization problem where the objective is a composition of two expected-value functions. We propose a new stochastic first-order method, namely the accelerated stochastic compositional proximal gradient (ASC-PG) method, ... More
Dimension counts for singular rational curves via semigroupsNov 26 2015Mar 05 2018We study singular rational curves in projective space, deducing conditions on their parametrizations from the value semigroups $\sss$ of their singularities. In particular, we prove that a natural heuristic for the codimension of the space of nondegenerate ... More
Constructing symplectomorphisms between symplectic torus quotientsMar 22 2019We identify a family of torus representations such that the corresponding singular symplectic quotients at the $0$-level of the moment map are graded regularly symplectomorphic to symplectic quotients associated to representations of the circle. For a ... More
Secant planes of a general curve via degenerationsJan 18 2019Feb 23 2019We study linear series on a general curve of genus g, whose images are exceptional with respect to their secant planes. Each such exceptional secant plane is algebraically encoded by an included linear series, whose number of base points computes the ... More
Combined Diffusion-Relaxometry MRI to Identify Dysfunction in the Human PlacentaOct 09 2018Mar 21 2019Purpose: A combined diffusion-relaxometry MR acquisition and analysis pipeline for in-vivo human placenta, which allows for exploration of coupling between T2* and apparent diffusion coefficient (ADC) measurements in a sub 10 minute scan time. Methods: ... More
Strongly interacting dynamics and the search for new physics at the LHCJan 15 2016Jan 28 2016We present results for the spectrum of a strongly interacting SU(3) gauge theory with $N_f = 8$ light fermions in the fundamental representation. Carrying out non-perturbative lattice calculations at the lightest masses and largest volumes considered ... More
Re-running the QCD shear viscosityNov 06 2017The remarkably small shear viscosity to entropy density ratio $\eta/s < 0.5$ of the quark-gluon plasma (QGP) is a key insight from heavy ion experiments. Nonetheless, the basic understanding of this `observable' still seems to be rudimentary, with existing ... More