Results for "David Thompson"

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Coding Sequence Density Estimation Via Topological PressureSep 27 2011Jan 08 2014We give a new approach to coding sequence (CDS) density estimation in genomic analysis based on the topological pressure, which we develop from a well known concept in ergodic theory. Topological pressure measures the "weighted information content" of ... More
The weak specification property for geodesic flows on CAT(-1) spacesJun 20 2016Jun 28 2018We prove that the geodesic flow on a compact locally CAT(-1) space has the weak specification property, and give various applications. We show that every H\"older potential on the space of geodesics has a unique equilibrium state. We establish the equidistribution ... More
Gamma Ray Pulsars: ObservationsJan 03 2001High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting ... More
Monitoring the Gamma-ray Sky through 4.5 Years of Fermi LAT Flare Advocate ServiceMar 17 2013The Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides for a quick look and review of the gamma-ray sky observed daily by the Fermi Large Area Telescope (LAT). The FA-GSW service provides alerts and communicates to the ... More
The Multiwavelength Approach to Unidentified Gamma-Ray SourcesJul 20 2004As the highest-energy photons, gamma rays have an inherent interest to astrophysicists and particle physicists studying high-energy, nonthermal processes. Gamma-ray telescopes complement those at other wavelengths, especially radio, optical, and X-ray, ... More
Sub-L* Galaxies at Redshifts z~4, 3, and 2: Their UV Luminosity Function and Luminosity DensitySep 15 2005We use very deep (R_lim=27) UGRI imaging to study the evolution of the faint end of the UV-selected galaxy luminosity function from z~4 to z~2. We find that the luminosity function evolves with time and that this evolution is differential with luminosity: ... More
Boundary Conditions for Interacting MembranesDec 17 2009Jan 29 2010We investigate supersymmetric boundary conditions in both the Bagger-Lambert and the ABJM theories of interacting membranes. We find boundary conditions associated to the fivebrane, the ninebrane and the M-theory wave. For the ABJM theory we are able ... More
Space Detectors for Gamma Rays (100 MeV - 100 GeV): from EGRET to Fermi LATJun 25 2015The design of spaceborne high-energy (E>100 MeV) gamma-ray detectors depends on two principal factors: (1) the basic physics of detecting and measuring the properties of the gamma rays; and (2) the constraints of operating such a detector in space for ... More
Gamma Ray Pulsars: Multiwavelength ObservationsDec 10 2003High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves ... More
A Quantum Bousso BoundMar 10 2003The Bousso bound requires that one quarter the area of a closed codimension two spacelike surface exceeds the entropy flux across a certain lightsheet terminating on the surface. The bound can be violated by quantum effects such as Hawking radiation. ... More
Keck Deep Fields. II. The UV Galaxy Luminosity Function at z~4, 3, and 2Jul 21 2005Jan 05 2006We use very deep UGRI multi-field imaging obtained at the Keck telescope to study the evolution of the rest-frame 1700A galaxy luminosity function as the Universe doubles its age from z~4 to z~2. The depth of our imaging allows us to constrain the faint ... More
Keck Deep Fields. III. Luminosity-dependent Evolution of the Ultraviolet Luminosity and Star Formation Rate Densities at z~4, 3, and 2May 17 2006We use the Keck Deep Fields UGRI catalog of z~4, 3, and 2 UV-selected galaxies to study the evolution of the rest-frame 1700A luminosity density at high redshift. The ability to reliably constrain the contribution of faint galaxies is critical and our ... More
Keck Deep Fields. I. Observations, Reductions, and the Selection of Faint Star-Forming Galaxies at Redshifts z~4, 3, and 2Jul 19 2005We introduce a very deep, R_lim~27, multicolor imaging survey of very faint star-forming galaxies at z~4, z~3, z~2.2, and z~1.7. This survey, carried out on the Keck I telescope, uses the very same UGRI filter system that is employed by the Steidel team ... More
AdS Solutions of 2D Type 0ADec 15 2003May 04 2004We present a two-parameter family of AdS solutions to the two-dimensional type 0A effective action.
Descent Relations in Type 0A/0BMay 31 2001Mar 26 2002The type 0 theories have twice as many stable D-branes as the type II theories. In light of this added complication, we find the descent relations for D-branes in the type 0A and 0B theories. In addition, we work out how the two types of D-branes differ ... More
A Thermodynamic Definition of Topological Pressure for Non-Compact SetsJul 14 2008Feb 11 2010We give a new definition of topological pressure for arbitrary (non-compact, non-invariant) Borel subsets of metric spaces. This new quantity is defined via a suitable variational principle, leading to an alternative definition of an equilibrium state. ... More
The Sum of Four Squares Over Real Quadratic Number FieldsOct 21 2016May 23 2018Well-known results of Lagrange and Jacobi prove that the every $m \in \mathbb N$ can be expressed as a sum of four integer squares, and the number $r(m)$ of such representations can be given by an explicit formula in $m$. In this paper, we prove that ... More
Explicit Models for Threefolds Fibred by K3 Surfaces of Degree TwoJan 25 2011Aug 17 2012We consider threefolds that admit a fibration by K3 surfaces over a nonsingular curve, equipped with a divisorial sheaf that defines a polarisation of degree two on the general fibre. Under certain assumptions on the threefold we show that its relative ... More
Degenerations of K3 Surfaces of Degree TwoOct 28 2010Dec 19 2011We consider a semistable degeneration of K3 surfaces, equipped with an effective divisor that defines a polarisation of degree two on a general fibre. We show that the map to the relative log canonical model of the degeneration maps every fibre to either ... More
An Unstable Change of Rings for Morava E-TheorySep 12 2014Mar 16 2018The Bousfield-Kan (or unstable Adams) spectral sequence can be constructed for various homology theories such as Brown-Peterson homology theory BP, Johnson-Wilson theory $E(n)$, or Morava $E$-theory $E_n$. For nice spaces the $E_2$-term is given by Ext ... More
Tori and Heegaard splittingsMar 27 2016Haken showed that the Heegaard splittings of reducible 3-manifolds are reducible, that is, a reducing 2-sphere can be found which intersects the Heegaard surface in a single simple closed curve. When the genus of the "interesting" surface increases from ... More
Dehn surgery on complicated fibered knots in the 3-sphereApr 17 2016Let K be a fibered knot in the 3-sphere. We show that if the monodromy of K is sufficiently complicated, then Dehn surgery on K cannot yield a lens space. Work of Yi Ni shows that if K has a lens space surgery then it is fibered. Combining this with our ... More
Network analysis reveals distinct clinical syndromes underlying acute mountain sicknessMar 26 2013Acute mountain sickness (AMS) is a common problem among visitors at high altitude, and may progress to life-threatening pulmonary and cerebral oedema in a minority of cases. International consensus defines AMS as a constellation of subjective, non-specific ... More
Computational Analysis of Perfect-Information Position AuctionsAug 04 2014After experimentation with other designs, the major search engines converged on the weighted, generalized second-price auction (wGSP) for selling keyword advertisements. Notably, this convergence occurred before position auctions were well understood ... More
Duality Symmetric String and M-TheoryJun 11 2013Dec 09 2014We review recent developments in duality symmetric string theory. We begin with the world sheet doubled formalism which describes strings in an extended space time with extra coordinates conjugate to winding modes. This formalism is T-duality symmetric ... More
Duality Symmetric Strings, Dilatons and O(d,d) Effective ActionsDec 07 2007Dec 10 2007We calculate the background field equations for the T-duality symmetric string building on previous work by including the effect of the Dilaton up to two-loops. Inclusion of the Dilaton allows us to obtain the full beta functionals of the duality symmetric ... More
The `Real' Schwarz LemmaDec 02 2010The purpose of this note is to discuss the real analogue of the Schwarz lemma from complex analysis.
The Robustness of Cosmological Hydrodynamic Simulation Predictions to Changes in Numerics and Cooling PhysicsOct 30 2018We test and improve the numerical schemes in our smoothed particle hydrodynamics (SPH) code for cosmological simulations, including the pressure-entropy formulation (PESPH), a time-dependent artificial viscosity, a refined timestep criterion, and metal-line ... More
An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30Feb 26 2015Feb 28 2015So far, roughly 40 quasars with redshifts greater than z=6 have been discovered. Each quasar contains a black hole with a mass of about one billion solar masses ($10^9 M_\odot$). The existence of such black holes when the Universe was less than 1 billion ... More
The weak specification property for geodesic flows on CAT(-1) spacesJun 20 2016We prove that the geodesic flow on a compact locally CAT(-1) space has the weak specification property, and give various applications of this property. We show that every H\"older continuous function on the space of geodesics has a unique equilibrium ... More
Cosmic Ray Studies with the Fermi Gamma-ray Space Telescope Large Area TelescopeJan 04 2012The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope provides both direct and indirect measurements of Galactic cosmic rays (CR). The LAT high-statistics observations of the 7 GeV - 1 TeV electron plus positron spectrum and limits on ... More
Realization of the Axial Next-Nearest-Neighbor Ising model in U$_3$Al$_2$Ge$_3$May 24 2017Nov 09 2017Here we report small-angle neutron scattering (SANS) measurements and theoretical modeling of U$_3$Al$_2$Ge$_3$. Analysis of the SANS data reveals a phase transition to sinusoidally modulated magnetic order, at $T_{\mathrm{N}}=63$~K to be second order, ... More
Membranes with a boundaryApr 01 2009May 07 2009We investigate the recently developed theory of multiple membranes. In particular, we consider open membranes, i.e. the theory defined on a membrane world volume with a boundary. We first restrict our attention to the gauge sector of the theory. We obtain ... More
Multiplier ideals of monomial space curvesJun 09 2010Feb 22 2011The goal of this paper is to produce a formula for the multiplier ideals of monomial space curves in the spirit of Howald's formula for the multiplier ideals of monomial ideals. This is achieved by constructing a toric blowup of affine space in such a ... More
A criterion for topological entropy to decrease under normalised Ricci flowNov 16 2009Dec 18 2009In 2004, Manning showed that the topological entropy of the geodesic flow for a surface of negative curvature decreases as the metric evolves under the normalised Ricci flow. It is an interesting open problem, also due to Manning, to determine to what ... More
Pulling subdivisions of cones and blowups of monomial ideals on affine toric varietiesDec 29 2016This short note solves the following problem: Given a map of normal toric varieties corresponding to a coherent subdivision of a cone, find an ideal such that the given map is the blowup of that ideal.
Timing and Other Artifacts in EPR ExperimentsApr 29 1997Re-evaluation of the evidence (some of it unpublished) shows that experimenters conducting Einstein-Podolsky-Bohm (EPR) experiments may have been deceived by various pre-conceptions and artifacts. False or unproven assumptions were made regarding, in ... More
Arithmetic functions at consecutive shifted primesMay 17 2014Aug 06 2014For each of the functions $f \in \{\phi, \sigma, \omega, \tau\}$ and every natural number $k$, we show that there are infinitely many solutions to the inequalities $f(p_n-1) < f(p_{n+1}-1) < \dots < f(p_{n+k}-1)$, and similarly for $f(p_n-1) > f(p_{n+1}-1) ... More
On the degrees of divisors of T^n-1Jun 11 2012Fix a field $F$. In this paper, we study the sets $\D_F(n) \subset [0,n]$ defined by [\D_F(n):= {0 \leq m \leq n: T^n-1\text{has a divisor of degree $m$ in} F[T]}.] When $\D_F(n)$ consists of all integers $m$ with $0 \leq m \leq n$, so that $T^n-1$ has ... More
A short note on the multiplier ideals of monomial space curvesJun 06 2014Nov 11 2015Thompson (2014) exhibits a formula for the multiplier ideal with multiplier lambda of a monomial curve C with ideal I as an intersection of a term coming from the I-adic valuation, the multiplier ideal of the term ideal of I, and terms coming from certain ... More
Four new eclipsing mid M-dwarf systems from the New Luyten Two Tenths catalogAug 09 2018Using data from the MEarth-North and MEarth-South transit surveys, we present the detection of eclipses in four mid M-dwarf systems: LP 107-25, LP 261-75, LP 796-24, and LP 991-15. Combining the MEarth photometry with spectroscopic follow-up observations, ... More
An exact tree projection algorithm for waveletsApr 16 2013We propose a dynamic programming algorithm for projection onto wavelet tree structures. In contrast to other recently proposed algorithms which only give approximate tree projections for a given sparsity, our algorithm is guaranteed to calculate the projection ... More
ADE surfaces and their moduliDec 21 2017Jan 12 2018We define a class of surfaces and surface pairs corresponding to the ADE root lattices and construct compactifications of their moduli spaces, generalizing Losev-Manin spaces of curves.
Bielliptic curves of genus 3 in the hyperelliptic moduliMay 20 2013In this paper we study bielliptic curves of genus 3 defined over an algebraically closed field $k$ and the intersection of the moduli space $\M_3^b$ of such curves with the hyperelliptic moduli $\H_3$. Such intersection $\S$ is an irreducible, 3-dimensional, ... More
Generalized beta-transformations and the entropy of unimodal mapsFeb 10 2016Jan 11 2017Generalized beta-transformations are the class of piecewise continuous interval maps given by taking the beta-transformation $x \mapsto \beta x ~\pmod 1$, where $\beta>1$, and replacing some of the branches with branches of constant negative slope. If ... More
A numerical study of the correspondence between paths in a causal set and geodesics in the continuumDec 13 2005This paper presents the results of a computational study related to the path-geodesic correspondence in causal sets. For intervals in flat spacetimes, and in selected curved spacetimes, we present evidence that the longest maximal chains (the longest ... More
The gauge structure of generalised diffeomorphismsAug 29 2012Oct 24 2012We investigate the generalised diffeomorphisms in M-theory, which are gauge transformations unifying diffeomorphisms and tensor gauge transformations. After giving an En(n)-covariant description of the gauge transformations and their commutators, we show ... More
Supersymmetric Branes in AdS_2 x S^2 x CY_3Jun 14 2004The problem of finding supersymmetric brane configurations in the near-horizon attractor geometry of a Calabi-Yau black hole with magnetic-electric charges (p^I,q_I) is considered. Half-BPS configurations, which are static for some choice of global AdS2 ... More
Isoperimetric problems in sectors with densityDec 02 2010We consider the isoperimetric problem in planar sectors with density $r^{p}$, and with density $a>1$ inside the unit disk and $1$ outside. We characterize solutions as a function of sector angle. We also solve the isoperimetric problem in $\mathbb{R}^{n}$ ... More
ASASSN-18di: discovery of a $ΔV \sim 10$ flare on a mid-M dwarfApr 12 2018We report and characterize a white-light superflare on a previously undiscovered M dwarf detected by the ASAS-SN survey. Employing various color-magnitude and color-spectral type relationships, we estimate several stellar parameters, including the quiescent ... More
Forming Super Star Clusters in the Central Starburst of NGC 253Apr 05 2018Oct 24 2018NGC 253 hosts the nearest nuclear starburst. Previous observations show a region rich in molecular gas, with dense clouds associated with recent star formation. We used ALMA to image the 350 GHz dust continuum and molecular line emission from this region ... More
Background Field Equations for the Duality Symmetric StringAug 16 2007Sep 13 2007This paper describes the background field equations for strings in T-duality symmetric formalisms in which the dimension of target space is doubled and the sigma model supplemented with constraints. These are calculated by demanding the vanishing of the ... More
Aspects of Multiple MembranesMar 25 2008This paper examines various aspects of the recently proposed theory of coincident membranes by Bagger and Lambert. These include the properties of open membranes and the resulting boundary theory with an interpretation in terms of the fivebrane and marginal ... More
The TOP-SCOPE survey of Planck Galactic Cold Clumps: Survey overview and results of an exemplar source, PGCC G26.53+0.17Nov 13 2017Dec 19 2017The low dust temperatures (<14 K) of Planck Galactic Cold Clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. TOP-SCOPE is a joint survey program targeting ~2000 PGCCs in J=1-0 transitions of ... More
The prestellar and protostellar population of R Coronae AustralisDec 09 2004Jan 19 2005We present 450 and 850 um maps of R Coronae Australis. We compare the maps to previous surveys of the region, and shed new light on the previously unknown nature of the protostellar sources at the centre of the cloud. We clarify the nature of two millimetre ... More
An Origin for Multi-Phase Gas in Galactic Winds and HalosJul 15 2015Dec 08 2015The physical origin of high velocity cool gas seen in galactic winds remains unknown. Following Wang (1995), we argue that radiative cooling in initially hot thermally-driven outflows can produce fast neutral atomic and photoionized cool gas. The inevitability ... More
Keck Deep Fields. IV. Luminosity Dependent Clustering and Galaxy Downsizing in UV-Selected Galaxies at z=4, 3, and 2Jun 10 2011We investigate the luminosity dependent clustering of rest-frame UV selected galaxies at z~4, 3, 2.2, and 1.7 in the Keck Deep Fields (KDFs), which are complete to R = 27 and cover 169 arcmin^2. We find that at z~4 and 3, UV-bright galaxies cluster more ... More
Mirror Symmetry for Lattice Polarized del Pezzo SurfacesSep 04 2017Mar 22 2018We describe a notion of lattice polarization for rational elliptic surfaces and weak del Pezzo surfaces, and describe the complex moduli of the former and the K\"{a}hler cone of the latter. We then propose a version of mirror symmetry relating these two ... More
Pure-minimal chain complexesDec 31 2017Oct 03 2018We introduce a notion of pure-minimality for chain complexes of modules and show that it coincides with (homotopic) minimality in standard settings, while being a more useful notion for complexes of flat modules. As applications, we characterize von Neumann ... More
Edge-based LBP description of surfaces with colorimetric patternsApr 11 2018In this paper we target the problem of the retrieval of colour patterns over surfaces. We generalize to surface tessellations the well known Local Binary Pattern (LBP) descriptor for images. The key concept of the LBP is to code the variability of the ... More
Measures of maximal entropy for suspension flows over the full shiftAug 01 2017Mar 12 2019We consider suspension flows with continuous roof function over the full shift $\Sigma$ on a finite alphabet. For any positive entropy subshift of finite type $Y \subset \Sigma$, we explictly construct a roof function such that the measure(s) of maximal ... More
Bursty and persistent properties of large-scale brain networks revealed with a point-based method for dynamic functional connectivityJan 13 2016In this paper, we present a novel and versatile method to study the dynamics of resting-state fMRI brain connectivity with a high temporal sensitivity. Whereas most existing methods often rely on dividing the time-series into larger segments of data (i.e. ... More
Network Inference from a Link-Traced Sample using Approximate Bayesian ComputationJan 14 2017We present a new inference method based on approximate Bayesian computation for estimating parameters governing an entire network based on link-traced samples of that network. To do this, we first take summary statistics from an observed link-traced network ... More
Sample average approximation with heavier tails II: localization in stochastic convex optimization and persistence results for the LassoNov 13 2017Oct 07 2018We present exponential finite-sample nonasymptotic deviation inequalities for the SAA estimator's near-optimal solution set over the class of stochastic optimization problems with heavy-tailed random \emph{convex} functions in the objective and constraints. ... More
Equilibrium states beyond specification and the Bowen propertyJun 17 2011Jun 16 2012It is well-known that for expansive maps and continuous potential functions, the specification property (for the map) and the Bowen property (for the potential) together imply the existence of a unique equilibrium state. We consider symbolic spaces that ... More
ADS Labs - Supporting Information Discovery in Science EducationOct 02 2012The SAO/NASA Astrophysics Data System (ADS) is an open access digital library portal for researchers in astronomy and physics, operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant, successfully serving the professional science ... More
Sample average approximation with heavier tails I: non-asymptotic bounds with weak assumptions and stochastic constraintsMay 02 2017Oct 07 2018We derive exponential finite-sample nonasymptotic deviation inequalities for the sample average approximation (SAA) estimator's near-optimal solution set and optimal value. In that respect, we give three contributions. First, our bounds do not require ... More
Measures of maximal entropy for suspension flows over the full shiftAug 01 2017Jul 06 2018We consider suspension flows with continuous roof function over the full shift $\Sigma$ on a finite alphabet. For any positive entropy subshift of finite type $Y \subset \Sigma$, we show there exists a roof function such that the measure(s) of maximal ... More
Distribution of squarefree values of sequences associated with elliptic curvesOct 12 2012May 02 2013Let E be a non-CM elliptic curve defined over Q. For each prime p of good reduction, E reduces to a curve E_p over the finite field F_p. For a given squarefree polynomial f(x,y), we examine the sequences f_p(E) := f(a_p(E), p), whose values are associated ... More
Duality Invariant M-theory: Gauged supergravities and Scherk-Schwarz reductionsJul 31 2012Oct 20 2012We consider the reduction of the duality invariant approach to M-theory by a U-duality group valued Scherk-Schwarz twist. The result is to produce potentials for gauged supergravities that are normally associated with non-geometric compactifications. ... More
Optimization and NP_R-Completeness of Certain FewnomialsApr 26 2009Nov 06 2010We give a high precision polynomial-time approximation scheme for the supremum of any honest n-variate (n+2)-nomial with a constant term, allowing real exponents as well as real coefficients. Our complexity bounds count field operations and inequality ... More
Strong symbolic dynamics for geodesic flow on CAT(-1) spaces and other metric Anosov flowsAug 13 2018We prove that the geodesic flow on a compact, locally CAT(-1) metric space can be coded by a suspension flow over an irreducible shift of finite type with H\"older roof function. This is achieved by showing that the geodesic flow is a metric Anosov flow, ... More
The Landscape of the Neutrino Mechanism of Core-Collapse Supernovae: Neutron Star and Black Hole Mass Functions, Explosion Energies and Nickel YieldsSep 01 2014Jan 05 2015If the neutrino luminosity from the proto-neutron star formed during a massive star core collapse exceeds a critical threshold, a supernova (SN) results. Using spherical quasi-static evolutionary sequences for hundreds of progenitors over a range of metallicities, ... More
Intrinsic ergodicity beyond specification: beta-shifts, S-gap shifts, and their factorsNov 11 2010Jun 17 2011We give sufficient conditions for a shift space $(\Sigma,\sigma)$ to be intrinsically ergodic, along with sufficient conditions for every subshift factor of $\Sigma$ to be intrinsically ergodic. As an application, we show that every subshift factor of ... More
Exploring the NRO Opportunity for a Hubble-sized Wide-field Near-IR Space Telescope -- NEW WFIRSTOct 29 2012Nov 02 2012We discuss scientific, technical and programmatic issues related to the use of an NRO 2.4m telescope for the WFIRST initiative of the 2010 Decadal Survey. We show that this implementation of WFIRST, which we call "NEW WFIRST," would achieve the goals ... More
Herschel and SCUBA-2 observations of dust emission in a sample of Planck cold clumpsNov 26 2017Dec 27 2017Analysis of all-sky Planck submillimetre observations and the IRAS 100um data has led to the detection of a population of Galactic cold clumps. The clumps can be used to study star formation and dust properties in a wide range of Galactic environments. ... More
A deep Large Binocular Telescope view of the Canes Venatici I dwarf galaxySep 21 2007Nov 06 2007We present the first deep color-magnitude diagram of the Canes Venatici I (CVnI) dwarf galaxy from observations with the wide field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, ... More
The JCMT and Herschel Gould Belt Surveys: A comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495Aug 15 2016We present a comparison of SCUBA-2 850-$\mu$m and Herschel 70--500-$\mu$m observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterising the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterise starless ... More
A temperate rocky super-Earth transiting a nearby cool starApr 18 2017M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy [1]. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy ... More
High-Resolution Radio Continuum Measurements of the Nuclear Disks of Arp 220Nov 04 2014We present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy. These images have both the angular resolution to study detailed morphologies of the two nuclei that power the system ... More
Hodge Numbers from Picard-Fuchs EquationsDec 30 2016Jun 18 2017Given a variation of Hodge structure over $\mathbb{P}^1$ with Hodge numbers $(1,1,\dots,1)$, we show how to compute the degrees of the Deligne extension of its Hodge bundles, following Eskin-Kontsevich-M\"oller-Zorich, by using the local exponents of ... More
The number of surfaces of fixed genus in an alternating link complementAug 14 2015Jun 27 2016Let $L$ be a prime alternating link with $n$ crossings. We show that for each fixed $g$, the number of genus $g$ incompressible surfaces in the complement of $L$ is bounded by a polynomial in $n$. Previous bounds were exponential in $n$.
Experimental similarity assessment for a collection of fragmented artifactsApr 11 2018In the Visual Heritage domain, search engines are expected to support archaeologists and curators to address cross-correlation and searching across multiple collections. Archaeological excavations return artifacts that often are damaged with parts that ... More
Effect of Collective Neutrino Oscillations on the Neutrino Mechanism of Core-Collapse SupernovaeJun 28 2011Jun 07 2012In the seconds after collapse of a massive star, the newborn proto-neutron star (PNS) radiates neutrinos of all flavors. The absorption of electron-type neutrinos below the radius of the stalled shockwave may drive explosions (the "neutrino mechanism"). ... More
Early Discoveries of New Gauge Bosons W' and Z' in Leptonic Decay Channels at ATLASOct 16 2008We present the potential of the ATLAS detector to discover new massive gauge bosons in their leptonic decay channels: W' -> l nu_l and Z' -> l+ l-. Emphasis is placed on early data-taking at the LHC with low luminosity (up to 1 fb^-1).
Electrodynamics of Magnetars: Implications for the Persistent X-ray Emission and Spindown of the Soft Gamma Repeaters and Anomalous X-ray PulsarsOct 31 2001Mar 01 2002(ABBREVIATED) We consider the structure of neutron star magnetospheres threaded by large-scale electrical currents, and the effect of resonant Compton scattering by the charge carriers (both electrons and ions) on the emergent X-ray spectra and pulse ... More
Variability in Optical Spectra of epsilon OrionisJan 23 2013Mar 02 2013We present the results of a time-series analysis of 130 echelle spectra of epsilon Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of Halpha (net) and He I 5876 were measured and radial ... More
Detailed Abundances of 15 Stars in the Metal-Poor Globular Cluster NGC 4833Mar 10 2015Apr 11 2015We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard abundance analysis ... More
Global Crustal Dynamics of Magnetars in Relation to their Bright X-ray OutburstsAug 08 2016This paper considers the yielding response of a neutron star crust to smooth, unbalanced Maxwell stresses imposed at the core-crust boundary, and the coupling of the dynamic crust to the external magnetic field. Stress buildup and yielding in a magnetar ... More
Alternating links have at most polynomially many Seifert surfaces of fixed genusSep 28 2018Let $L$ be a non-split prime alternating link with $n>0$ crossings. We show that for each fixed $g$, the number of genus-$g$ Seifert surfaces for $L$ is bounded by an explicitly given polynomial in $n$. The result also holds for all spanning surfaces ... More
Mirror symmetry, Tyurin degenerations and fibrations on Calabi-Yau manifoldsJan 29 2016Nov 07 2016We investigate a potential relationship between mirror symmetry for Calabi-Yau manifolds and the mirror duality between quasi-Fano varieties and Landau-Ginzburg models. More precisely, we show that if a Calabi-Yau admits a so-called Tyurin degeneration ... More
Uniform Preconditioners For The Mixed Darcy ProblemDec 03 2018Preconditioners for porous media flow problems in mixed form are frequently based on H(div) preconditioners rather than the pressure Schur complement. We show that when the permeability, K, is small the pressure Schur complement must also be addressed ... More
Homotopy categories of totally acyclic complexes with applications to the flat-cotorsion theoryDec 11 2018We introduce a notion of total acyclicity associated to a subcategory of an abelian category and consider the Gorenstein objects they define. These Gorenstein objects form a Frobenius category, whose induced stable category is equivalent to the homotopy ... More
Equilibrium states for Mañé diffeomorphismsMar 16 2017Oct 24 2017We study thermodynamic formalism for the family of robustly transitive diffeomorphisms introduced by Ma\~n\'e, establishing existence and uniqueness of equilibrium states for natural classes of potential functions. In particular, we characterize the SRB ... More
10^{-7} contrast ratio at 4.5Lambda/D: New results obtained in laboratory experiments using nano-fabricated coronagraph and multi-Gaussian shaped pupil masksApr 05 2005We present here new experimental results on high contrast imaging of 10^{-7} at 4.5Lambda/D (Lambda = 0.820 microns) by combining a circular focal plane mask (coronagraph) of 2.5Lambda/D diameter and a multi-Gaussian pupil plane mask. Both the masks were ... More
Infrared Dark Cloud Cores in the SCUBA Legacy CatalogueJul 29 2009We present an investigation of candidate Infrared Dark Cloud cores as identified by Simon et al. (2006) located within the SCUBA Legacy Catalogue. After applying a uniform noise cut to the Catalogue data we identify 154 Infrared Dark Cloud cores that ... More
Commuting planar polynomial vector fields for conservative Newton systemsFeb 02 2018We study the problem of characterizing polynomial vector fields that commute with a given polynomial vector field on a plane. It is a classical result that one can write down solution formulas for an ODE that corresponds to a planar vector field that ... More
Large deviations for systems with non-uniform structureApr 19 2013Jul 23 2015We use a weak Gibbs property and a weak form of specification to derive level-2 large deviations principles for symbolic systems equipped with a large class of reference measures. This has applications to a broad class of symbolic systems, including $\beta$-shifts, ... More
Integrability and non-Integrability in N=2 SCFTs and their Holographic BackgroundsApr 23 2018May 16 2018We show that the string worldsheet theory of Gaiotto-Maldacena holographic duals to N=2 superconformal field theories generically fails to be classically integrable. We demonstrate numerically that the dynamics of a winding string configuration possesses ... More
Quantitative $C^1$-estimates by Bismut formulaeJul 22 2017Feb 05 2018For a $C^2$ function $u$ and an elliptic operator $L$, we prove a quantitative estimate for the derivative $du$ in terms of local bounds on $u$ and $Lu$. An integral version of this estimate is then used to derive a condition for the zero-mean value property ... More