Results for "David M. Ambrose"

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Existence theory for a time-dependent mean field games model of household wealthApr 12 2019We study a nonlinear system of partial differential equations arising in macroeconomics which utilizes a mean field approximation. This system together with the corresponding data, subject to two moment constraints, is a model for debt and wealth across ... More
Local Existence Theory for Derivative Nonlinear Schrödinger Equations with Non-Integer Power NonlinearitiesJan 28 2014We study a derivative nonlinear Schr\"{o}dinger equation, allowing non-integer powers in the nonlinearity, $|u|^{2\sigma} u_x$. Making careful use of the energy method, we are able to establish short-time existence of solutions with initial data in the ... More
Global paths of time-periodic solutions of the Benjamin-Ono equation connecting pairs of traveling wavesNov 26 2008Jun 10 2010We classify all bifurcations from traveling waves to non-trivial time-periodic solutions of the Benjamin-Ono equation that are predicted by linearization. We use a spectrally accurate numerical continuation method to study several paths of non-trivial ... More
Computation of Time-Periodic Solutions of the Benjamin-Ono EquationApr 23 2008Jun 09 2010We present a spectrally accurate numerical method for finding non-trivial time-periodic solutions of non-linear partial differential equations. The method is based on minimizing a functional (of the initial condition and the period) that is positive unless ... More
Dispersion vs. anti-diffusion: well-posedness in variable coefficient and quasilinear equations of KdV-typeMay 11 2012We study the well-posedness of the initial value problem on periodic intervals for linear and quasilinear evolution equations for which the leading-order terms have three spatial derivatives. In such equations, there is a competition between the dispersive ... More
Nonexistence of small doubly periodic solutions for dispersive equationsJun 05 2014We study the question of existence of time-periodic, spatially periodic solutions for dispersive evolution equations, and in particular, we introduce a framework for demonstrating the nonexistence of such solutions. We formulate the problem so that doubly ... More
Global existence and analyticity for the 2D Kuramoto-Sivashinsky equationAug 29 2017There is little analytical theory for the behavior of solutions of the Kuramoto-Sivashinsky equation in two spatial dimensions over long times. We study the case in which the spatial domain is a two-dimensional torus. In this case, the linearized behavior ... More
Global bifurcation theory for periodic traveling interfacial gravity-capillary wavesNov 20 2014Dec 29 2014We consider the global bifurcation problem for spatially periodic traveling waves for two-dimensional gravity-capillary vortex sheets. The two fluids have arbitrary constant, non-negative densities (not both zero), the gravity parameter can be positive, ... More
Ill-posedness of degenerate dispersive equationsApr 13 2011In this article we provide numerical and analytical evidence that some degenerate dispersive partial differential equations are ill-posed. Specifically we study the K(2,2) equation $u_t = (u^2)_{xxx} + (u^2)_{x}$ and the "degenerate Airy" equation $u_t ... More
Existence theory for magma equations in dimension two and higherJun 14 2017Jul 08 2018We examine a degenerate, dispersive, nonlinear wave equation related to the evolution of partially molten rock in dimensions two and higher. This simplified model, for a scalar field capturing the melt fraction by volume, has been studied by direct numerical ... More
Serfati solutions to the 2D Euler equations on exterior domainsJan 12 2014We prove existence and uniqueness of a weak solution to the incompressible 2D Euler equations in the exterior of a bounded smooth obstacle when the initial data is a bounded divergence-free velocity field having bounded scalar curl. This work completes ... More
Confinement of vorticity for the 2D Euler-alpha equationsFeb 27 2018In this article we consider weak solutions of the Euler-$\alpha$ equations in the full plane. We take, as initial unfiltered vorticity, an arbitrary nonnegative, compactly supported, bounded Radon measure. Global well-posedness for the corresponding initial ... More
Determination of the number of $ψ^{\prime}$ event at BESIIISep 27 2012Sep 29 2012The number of $\psp$ events accumulated by the BESIII experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is $106.41\times(1.00\pm 0.81%)\times 10^{6} $. The error is systematic only; the statistical ... More
ScotGrid: Providing an Effective Distributed Tier-2 in the LHC EraOct 23 2009ScotGrid is a distributed Tier-2 centre in the UK with sites in Durham, Edinburgh and Glasgow. ScotGrid has undergone a huge expansion in hardware in anticipation of the LHC and now provides more than 4MSI2K and 500TB to the LHC VOs. Scaling up to this ... More
Observation of a charged (DD*bar)- mass peak in e+e- --> pi+ (DD*bar)- at Ecm=4.26 GeVOct 04 2013Oct 08 2013We report on a study of the process e+e- --> pi+(D D*bar)- at Ecm=4.26 GeV using a 525 /pb data sample collected with the BESIII detector at the BEPCII storage ring. A distinct charged structure is observed in the (DD*bar)- invariant mass distribution. ... More
Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuumFeb 11 2016In many transition metal oxides (TMOs), oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth ... More
Observation of the Narrow State $X(3872)\to J/ψπ^{+}π^{-}$ in $\bar{p}p$ Collisions at $\sqrt{s}=1.96 \TeV$Dec 05 2003We report the observation of a narrow state decaying into $J/\psi\pi^+\pi^-$ and produced in $220 pb^{-1}$ of $\bar{p} p $ collisions at $\sqrt{s}=1.96 TeV$ in the CDF II experiment. We observe $ 730 \pm 90 $ decays. The mass is measured to be $3871.3 ... More
Reversal of the lattice structure in SrCoOx epitaxial thin films studied by real-time optical spectroscopy and first-principles calculationsAug 10 2013Using real-time spectroscopic ellipsometry, we directly observed a reversible lattice and electronic structure evolution in SrCoOx (x = 2.5 - 3) epitaxial thin films. Drastically different electronic ground states, which are extremely susceptible to the ... More
Instruction-set Selection for Multi-application based ASIP Design: An Instruction-level StudyMar 28 2014Efficiency in embedded systems is paramount to achieve high performance while consuming less area and power. Processors in embedded systems have to be designed carefully to achieve such design constraints. Application Specific Instruction set Processors ... More
Single-Strip Triangulation of Manifolds with Arbitrary TopologyMay 10 2004Triangle strips have been widely used for efficient rendering. It is NP-complete to test whether a given triangulated model can be represented as a single triangle strip, so many heuristics have been proposed to partition models into few long strips. ... More
A new part-per-million measurement of the positive muon lifetime and determination of the Fermi ConstantSep 29 2011The Fermi Constant, G_F, describes the strength of the weak force and is determined most precisely from the mean life of the positive muon, tau_mu. Advances in theory have reduced the theoretical uncertainty on G_F as calculated from tau_mu to a few tenths ... More
Gamma-Ray Line Observations with RHESSIApr 30 2004The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has been observing gamma-ray lines from the Sun and the Galaxy since its launch in February 2002. Here I summarize the status of RHESSI observations of solar lines (nuclear de-excitation, ... More
The Darkness of Spin-0 Dark RadiationJul 09 2014Dec 01 2014We show that the scattering of a general spin-0 sector of dark radiation off the pre-recombination thermal plasma results in undetectably small spectral distortions of the Cosmic Microwave Background.
What the F-measure doesn't measure: Features, Flaws, Fallacies and FixesMar 22 2015The F-measure or F-score is one of the most commonly used single number measures in Information Retrieval, Natural Language Processing and Machine Learning, but it is based on a mistake, and the flawed assumptions render it unsuitable for use in most ... More
Data Preservation in High Energy PhysicsJan 17 2011Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are in many cases unique. At the same time, HEP has no coherent strategy for data preservation and re-use, and many important and complex data ... More
Multi-Lepton and Isolated Lepton Events at HERASep 16 2009Measurements of the production of events containing isolated high energy leptons (electrons and muons) produced in ep collisions have been performed with the H1 and ZEUS detectors at HERA, using data collected in the period 1994-2007. Topologies with ... More
Thermal rectification effects of multiple semiconductor quantum dot junctionsApr 18 2010Based on the multiple energy level Anderson model, this study theoretically examines the thermoelectric effects of semiconductor quantum dots (QDs) in the nonlinear response regime. The charge and heat currents in the sequential tunneling process are ... More
An artificial boundary approach for short-ranged interactionsNov 12 2015Jun 16 2016Real physical systems are only understood, experimentally or theoretically, to a finite resolution so in their analysis there is generally an ignorance of possible short-range phenomena. It is also well-known that the boundary conditions of wavefunctions ... More
Red Giant Branch Bump Star Counts in Data and Stellar ModelsSep 22 2014Oct 13 2014We compare model predictions to observations of star counts in the red giant branch bump (RGBB) relative to the number density of first-ascent red giant branch at the magnitude of the RGBB, $EW_{RGBB}$. The predictions are shown to exceed the data by ... More
The Age and Helium Abundance of the Galactic BulgeJul 13 2013I discuss the age and helium abundance of the Galactic bulge stellar population. I present examples as to how age and helium abundance can be degenerate observationally, and thus, how unstated assumptions of the helium-metallicity relation can result ... More
The Interstellar Extinction Toward the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae starsMar 22 2016I review the literature covering the issue of interstellar extinction toward the Milky Way bulge, with emphasis placed on findings from planetary nebulae, RR Lyrae, and red clump stars. I also report on observations from HI gas and globular clusters. ... More
LUNA: An algorithm for generating dynamic planet-moon transitsMay 17 2011Apr 23 2012It has been previously shown that moons of extrasolar planets may be detectable with the Kepler Mission, for moon masses above ~0.2 Earth masses Kipping et al. 2009c. Transit timing effects have been formerly identified as a potent tool to this end, exploiting ... More
Parametrizing the exoplanet eccentricity distribution with the Beta distributionJun 20 2013Jun 26 2013It is suggested that the distribution of orbital eccentricities for extrasolar planets is well-described by the Beta distribution. Several properties of the Beta distribution make it a powerful tool for this purpose. For example, the Beta distribution ... More
Transiting planets - lightcurve analysis for eccentric orbitsJul 01 2008Dec 12 2008Transiting planet lightcurves have historically been used predominantly for measuring the depth and hence ratio of the planet-star radii, p. Equations have been previously presented by Seager & Mallen-Ornelas (2003) for the analysis of the total and trough ... More
Taking a Detour to Zero: An Alternative Formalization of Functions Beyond PRSep 23 2016Oct 11 2016There are two well known systems formalizing total recursion beyond primitive recursion (\textbf{PR}), system \textbf{T} by G\"odel and system \textbf{F} by Girard and Reynolds. system \textbf{T} defines recursion on typed objects and can construct every ... More
Concurrent Coding: A Reason to Think Differently About Encoding Against Noise, Burst Errors and JammingJan 28 2019Concurrent coding is an unconventional encoding technique that simultaneously provides protection against noise, burst errors and interference. This simple-to-understand concept is investigated by distinguishing 2 types of code, open and closed, with ... More
Invertible Carnot GroupsAug 20 2014Aug 18 2016We characterize Carnot groups admitting a 1-quasiconformal metric inversion as the Lie groups of Heisenberg type whose Lie algebras satisfy the $J^2$-condition, thus characterizing a special case of inversion invariant bi-Lipschitz homogeneity. A more ... More
The universal simplicial bundle is a simplicial groupApr 22 2012Jul 02 2012The classical universal bundle functor W:sGrp(C) \to sSet(C) for simplicial groups in a category C with finite products lifts to a monad on sGrp(C). This result extends to simplicial algebras for any Lawvere theory containing that of groups.
Range separation: The divide between local structures and field theoriesFeb 08 2019Mar 14 2019This work presents parallel histories of the development of two modern theories of condensed matter: the theory of electron structure in quantum mechanics, and the theory of liquid structure in statistical mechanics. Comparison shows that key revelations ... More
Using integral transforms to estimate higher order derivativesJun 20 2007Integral transformations are used to estimate high order derivatives of various special functions. Applications are given to numerical integration, where estimates of high order derivatives of the integrand are needed to achieve bounds on the error. The ... More
Integrable Background GeometriesMar 14 2014Mar 28 2014This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed ... More
Exploring The Lambda Model Of The Hybrid SuperstringSep 17 2016Sep 21 2016The purpose of this contribution is to initiate the study of integrable deformations for different superstring theory formalisms that manifest the property of (classical) integrability. In this paper we choose the hybrid formalism of the superstring in ... More
Review of Charniak's "Statistical Language Learning"Jun 21 1995This article is an in-depth review of Eugene Charniak's book, "Statistical Language Learning". The review evaluates the appropriateness of the book as an introductory text for statistical language learning for a variety of audiences. It also includes ... More
Throwing fuel on the embers: Probability or Dichotomy, Cognitive or Linguistic?Jul 01 2016Prof. Robert Berwick's abstract for his forthcoming invited talk at the ACL2016 workshop on Cognitive Aspects of Computational Language Learning revives an ancient debate. Entitled "Why take a chance?", Berwick seems to refer implicitly to Chomsky's critique ... More
Evaluation Evaluation a Monte Carlo studyApr 03 2015Over the last decade there has been increasing concern about the biases embodied in traditional evaluation methods for Natural Language Processing/Learning, particularly methods borrowed from Information Retrieval. Without knowledge of the Bias and Prevalence ... More
Search for First Generation Leptoquarks in ep Collisions at HERAFeb 14 2013A search for first generation scalar and vector leptoquarks produced in ep collisions is performed by the H1 Collaboration at HERA. The full H1 data sample is used in the analysis, corresponding to an integrated luminosity 446 pb^-1. No evidence for the ... More
Supersymmetry of Affine Toda Models as Fermionic Symmetry Flows of the Extended mKdV HierarchySep 16 2009May 27 2010We couple two copies of the supersymmetric mKdV hierarchy by means of the algebraic dressing technique. This allows to deduce the whole set of $(N,N)$ supersymmetry transformations of the relativistic sector of the extended mKdV hierarchy and to interpret ... More
On the Case for a Super Tau-Charm FactoryMay 13 2006May 20 2006Design studies for a Super Flavor Factory (SFF), an asymmetric energy e+e- collider utilizing International Linear Collider (ILC) techniques and technology, are in progress. The capablity to run at center-of-mass energies near 3.770 GeV could be included ... More
Efficient, uninformative sampling of limb darkening coefficients for two-parameter lawsJul 31 2013Aug 14 2013Stellar limb darkening affects a wide range of astronomical measurements and is frequently modelled with a parametric model using polynomials in the cosine of the angle between the line of sight and the emergent intensity. Two-parameter laws are particularly ... More
The Transits of Extrasolar Planets with MoonsMay 16 2011Apr 23 2012The search for extrasolar planets is strongly motivated by the goal of characterizing how frequent habitable worlds and life may be within the Galaxy. Whilst much effort has been spent on searching for Earth-like planets, large moons may also be common, ... More
A Generalized Resolution Proof Schema and the Pigeonhole PrincipleAug 28 2016The schematic CERES method is a method of cut elimination for proof schemata, that is a sequence of proofs with a recursive construction. Proof schemata can be thought of as a way to circumvent the addition of an induction rule to the LK-calculus. In ... More
Using Perturbative Least Action to Reconstruct the Local GroupSep 04 2000Sep 06 2000In this paper, we apply the Perturbative Least Action Method to model the Local Group of galaxies for various Cosmological models. We show that though the galaxy masses are theoretically good discriminators of $\Omega_M$ given some observed MW and M31 ... More
Toward a sub-ppm measurement of the Fermi constantJun 21 2010The Fermi constant, G_F, describes the strength of the weak force and is determined most precisely from the mean life of the positive muon, tau_mu. Advances in theory have reduced the theoretical uncertainty on G_F as calculated from tau_mu to a few tenths ... More
Concurrent codes: A holographic-type encoding robust against noise and lossApr 16 2015Sep 07 2015Concurrent coding is an encoding scheme with "holographic" type properties that are shown here to be robust against a significant amount of noise and signal loss. This single encoding scheme is able to correct for random errors and burst errors simultaneously, ... More
A Theoretical Investigation Into Energy Transfer In Photosynthetic Open Quantum SystemsMar 11 2015This thesis looks at the electronic energy transfer in the Fenna-Matthews-Olson complex, in which evidence of long-lived coherence has been observed in 2-dimensional infrared experiments. I use three techniques: the numerically exact Hierarchical Equations ... More
The geometry of the Toda equationAug 30 1999Jan 26 2000I show that solutions of the SU(infinity) Toda field equation generating a fixed Einstein-Weyl space are governed by a linear equation on the Einstein-Weyl space. From this, obstructions to the existence of Toda solutions generating a given Einstein-Weyl ... More
A class of series acceleration formulae for Catalan's constantJun 03 2007In this note, we develop transformation formulae and expansions for the log tangent integral, which are then used to derive series acceleration formulae for certain values of Dirichlet L-functions, such as Catalan's constant. The formulae are characterized ... More
On the Sum Formula for Multiple q-Zeta ValuesNov 12 2004Multiple q-zeta values are a 1-parameter generalization (in fact, a q-analog) of the multiple harmonic sums commonly referred to as multiple zeta values. These latter are obtained from the multiple q-zeta values in the limit as q tends to 1. Here, we ... More
Some remarks on sinc integrals and their connection with combinatorics, geometry and probabilityMay 07 2007We give an alternative, combinatorial/geometrical evaluation of a class of improper sinc integrals studied by the Borweins. A probabilistic interpretation is also noted and used to shed light on a related combinatorial identity.
An infinite series for the natural logarithm that converges throughout its domain and makes concavity transparentApr 17 2012The natural logarithm can be represented by an infinite series that converges for all positive real values of the variable, and which makes concavity patently obvious. Concavity of the natural logarithm is known to imply, among other things, the fundamental ... More
A q-analog of Euler's decomposition formula for the double zeta functionJan 31 2005The double zeta function was first studied by Euler in response to a letter from Goldbach in 1742. One of Euler's results for this function is a decomposition formula, which expresses the product of two values of the Riemann zeta function as a finite ... More
Verhulst's logistic curveJun 21 2007We observe that the elementary logistic differential equation dP/dt=(1-P/M)kP may be solved by first changing the variable to R=(M-P)/P. This reduces the logistic differential equation to the simple linear differential equation dR/dt=-kR, which can be ... More
Hamiltonian quantization of solitons in the $φ^4_{1+1}$ quantum field theory. I. The semiclassical mass shiftApr 04 2019We study of the interaction of a scalar quantum field $\phi $ with a fixed (external) electromagnetic field $A^{ext}_\mu dx^\mu$ in two dimensional space-time. The dynamics is determined by the action functional \[ S\,=\,\int\,\Bigl(\frac{1}{2}\partial_\mu\phi\partial^\mu\phi- ... More
One mask to rule them all: Writing arbitrary intensity distributions by scanning a single illuminated spatially-random screenApr 21 2019Arbitrary intensity distributions may be written by transversely scanning a single spatially-random screen that is normally illuminated by spatially but not necessarily temporally uniform radiation or matter wave fields. The arbitrariness, of the written ... More
Towards a Direct, By-Need Evaluator for Dependently Typed LanguagesSep 23 2015We present a C-language implementation of the lambda-pi calculus by extending the (call-by-need) stack machine of Ariola, Chang and Felleisen to hold types, using a typeless- tagless- final interpreter strategy. It has the advantage of expressing all ... More
Statistical Decision-Tree Models for ParsingApr 29 1995Syntactic natural language parsers have shown themselves to be inadequate for processing highly-ambiguous large-vocabulary text, as is evidenced by their poor performance on domains like the Wall Street Journal, and by the movement away from parsing-based ... More
Visualization of Tradeoff in Evaluation: from Precision-Recall & PN to LIFT, ROC & BIRDMay 03 2015Evaluation often aims to reduce the correctness or error characteristics of a system down to a single number, but that always involves trade-offs. Another way of dealing with this is to quote two numbers, such as Recall and Precision, or Sensitivity and ... More
Search for Lepton Flavour Violation at HERAFeb 14 2013A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep to mu-X and ep to tau-X is performed by the H1 Collaboration at HERA. The full H1 ep data sample taken at a ... More
Search for Lepton Flavour Violation at HERAAug 04 2011A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep -> mu X and ep -> tau X is performed by the H1 experiment at HERA. The full H1 ep data sample taken at a centre-of-mass ... More
Data Preservation and Long Term Analysis in High Energy PhysicsJul 09 2009High energy physics data is a long term investment and contains the potential for physics results beyond the lifetime of a collaboration. Many existing experiments are concluding their physics programs, and looking at ways to preserve their data heritage. ... More
A Pair of Difference Differential Equations of Euler-Cauchy TypeOct 06 2003We study two classes of linear difference differential equations analogous to Euler-Cauchy ordinary differential equations, but in which multiple arguments are shifted forward or backward by fixed amounts. Special cases of these equations have arisen ... More
Logarithmic Time Parallel Bayesian InferenceJan 30 2013I present a parallel algorithm for exact probabilistic inference in Bayesian networks. For polytree networks with n variables, the worst-case time complexity is O(log n) on a CREW PRAM (concurrent-read, exclusive-write parallel random-access machine) ... More
Time Eigenvalues for the One-dimensional Infinite Square WellDec 08 2009Discrete time eigenvalues are found for the Infinite Square Well.
Exacerbating the cosmological constant problem with interacting dark energyJun 05 2016Future cosmological surveys will probe the expansion history of the universe and constrain phenomenological models of dark energy. Such models do not address the fine-tuning problem of the vacuum energy, i.e. the cosmological constant problem (c.c.p.), ... More
Tunneling Current Spectra of a Metal Core/Semiconductor Shell Quantum Dot MoleculeApr 15 2013The transport properties of a metal core/semiconductor shell quantum dot molecule (QDM) embedded in a matrix connected to metallic electrodes are theoretically studied in the framework of Keldysh Green function technique. The effects of the electron plasmon ... More
Fano interference effect on the transition spectrum of single electron transistorsNov 20 2005We theoretically study the intraband transition spectrum of single electron transistors (SETs) composed of individual self-assembled quantum dots. The polarization of SETs is obtained by using the nonequilibrium Green's function technique and the Anderson ... More
A Fast Chi-squared Technique For Period Search of Irregularly Sampled DataJan 14 2009A new, computationally- and statistically-efficient algorithm, the Fast $\chi^2$ algorithm, can find a periodic signal with harmonic content in irregularly-sampled data with non-uniform errors. The algorithm calculates the minimized $\chi^2$ as a function ... More
Uncertainties in The Interstellar Extinction Curve and the Cepheid Distance to M101Jan 21 2015I revisit the Cepheid-distance determination to the nearby spiral galaxy M101 (Pinwheel Galaxy) of Shappee & Stanek (2011), in light of several recent investigations questioning the shape of the interstellar extinction curve at $\lambda \approx 8,000$ ... More
The One-Loop H^2R^3 and H^2(DH)^2R Terms in the Effective ActionJul 22 2008Mar 01 2009We consider the one-loop B^2h^3 and B^4h amplitudes in type II string theory, where B is the NS-NS two-form and h the graviton, and expand to lowest order in alpha'. After subtracting diagrams due to quartic terms in the effective action, we determine ... More
The One-Loop Five-Graviton Amplitude and the Effective ActionJul 15 2008Mar 01 2009We consider the one-loop five-graviton amplitude in type II string theory calculated in the light-cone gauge. Although it is not possible to explicitly evaluate the integrals over the positions of the vertex operators, a low-energy expansion can be obtained, ... More
Kinematic Properties of Globally-Propagating Waves in the Solar CoronaFeb 20 2012Globally-propagating coronal bright fronts (CBFs) in the solar corona are among the most dramatic manifestations of solar activity, but are not well understood despite strong links with both solar flares and coronal mass ejections. Extreme UltraViolet ... More
Arithmetic, Infinite Trees, and Second-order Subsystems: Notes and ObservationsOct 13 2016Work in progress concerning alternative formalizations of arithmetic.
Generalized Palindromic Continued FractionsApr 22 2016In this paper we introduce a generalization of palindromic continued fractions as studied by Adamczewski and Bugeaud. We refer to these generalized palindromes as $m$-palindromes, where $m$ ranges over the positive integers. We provide a simple transcendence ... More
Efficient, uninformative sampling of limb-darkening coefficients for a three-parameter lawSep 11 2015Oct 30 2015Stellar limb-darkening impacts a wide range of astronomical measurements. The accuracy to which it is modelled limits the accuracy in any covariant parameters of interest, such as the radius of a transiting planet. With the ever growing availability of ... More
In Search of ExomoonsMay 06 2014Two decades ago, astronomers began detecting planets orbiting stars other than our Sun, so-called exoplanets. Since that time, the rate of detections and the sensitivity to ever-smaller planets has improved dramatically with several Earth-sized planets ... More
Characterizing Distant Worlds with Asterodensity ProfilingNov 05 2013Jun 09 2014Eclipsing systems, such as transiting exoplanets, allow one to measure the mean stellar density of the host star under various idealized assumptions. Asterodensity Profiling (AP) compares this density to an independently determined value in order to check ... More
Investigations of approximate expressions for the transit durationApr 21 2010In this work, we investigate the accuracy of various approximate expressions for the transit duration of a detached binary against the exact solution, found through solving a quartic equation. Additionally, a new concise approximation is derived, which ... 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
Selfdual Einstein metrics and conformal submersionsJan 07 2000Weyl derivatives, Weyl-Lie derivatives and conformal submersions are defined, then used to generalize the Jones-Tod correspondence between selfdual 4-manifolds with symmetry and Einstein-Weyl 3-manifolds with an abelian monopole. In this generalization, ... More
Embeddings of weighted graphs in Erdős-type settingsDec 11 2017Many recent results in combinatorics concern the relationship between the size of a set and the number of distances determined by pairs of points in the set. One extension of this question considers configurations within the set with a specified pattern ... More
Partition Identities for the Multiple Zeta FunctionFeb 06 2004We define a class of expressions for the multiple zeta function, and show how to determine whether an expression in the class vanishes identically. The class of such identities, which we call partition identities, is shown to coincide with the class of ... More
Counting the Positive Rationals: A Brief SurveySep 01 2005We discuss some examples that illustrate the countability of the positive rational numbers and related sets. Techniques include radix representations, Godel numbering, the fundamental theorem of arithmetic, continued fractions, Egyptian fractions, and ... More
Elementary Proof of MacMahon's ConjectureDec 01 1997Major Percy A. MacMahon's first paper on plane partitions included a conjectured generating function for symmetric plane partitions. This conjecture was proven almost simultaneously by George Andrews and Ian Macdonald, Andrews using the machinery of basic ... More
Ramanujan's formula for the logarithmic derivative of the gamma functionMay 07 2005We prove a remarkable formula of Ramanujan for the logarithmic derivative of the gamma function, which converges more rapidly than classical expansions, and which is stated without proof in Ramanujan's notebooks. The formula has a number of very interesting ... More
On a claim of Ramanujan about certain hypergeometric seriesMay 03 2005We state and prove a claim of Ramanujan. As a consequence, a large class of Saalchutzian hypergeometric series is summed in closed form.
Three alternating sign matrix identities in search of bijective proofsJul 18 2000This paper highlights three known identities, each of which involves sums over alternating sign matrices. While proofs of all three are known, the only known derivations are as corollaries of difficult results. The simplicity and natural combinatorial ... More
Continuous Probability Distributions from Finite DataAug 07 1998Recent approaches to the problem of inferring a continuous probability distribution from a finite set of data have used a scalar field theory for the form of the prior probability distribution. This letter presents a more general form for the prior distribution ... More
Finite homogeneous geometriesJan 18 2017This paper reproduces the text of a part of the Author's DPhil thesis. It gives a proof of the classification of non-trivial, finite homogeneous geometries of sufficiently high dimension which does not depend on the classification of the finite simple ... More
Galaxy-Galaxy Flexion: Weak Lensing to Second OrderJun 16 2004Oct 15 2004In this paper, we develop a new gravitational lensing inversion technique. While traditional approaches assume that the lensing field varies little across a galaxy image, we note that this variation in the field can give rise to a ``Flexion'' or bending ... More