Results for "Jeremy S. Perkins"

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Cherenkov and Jansky: Our Understanding of AGN at the Highest EnergiesJun 21 2012Misaligned blazars have been the subject of some of the most successful radio and gamma-ray multiwavelength campaigns. These campaigns have included many of the major ground and space based gamma-ray telescopes and span decades of energy. Even though ... More
Asynchronous Stochastic Approximation with Differential InclusionsDec 10 2011The asymptotic pseudo-trajectory approach to stochastic approximation of Benaim, Hofbauer and Sorin is extended for asynchronous stochastic approximations with a set-valued mean field. The asynchronicity of the process is incorporated into the mean field ... More
Exactness of Bohr-Sommerfeld quantisation for two non-central potentialsJul 26 2018In this paper we demonstrate the integrability of the Hamilton-Jacobi equation for two non-central potentials in spherical polar coordinates, and present complete solutions for the classically bound orbits. We then show that the semiclassical method of ... More
VERITAS Observations of the Coma Cluster of GalaxiesOct 01 2008Clusters of galaxies are one of the few prominent classes of objects predicted to emit gamma rays not yet detected by satellites like EGRET or ground-based Imaging Atmospheric Cherenkov Telescopes (IACTs). The detection of Very High Energy (VHE, E > 100 ... More
Casimir Interactions between Magnetic Flux Tubes in a Dense LatticeJul 28 2014Feb 18 2015We use the worldline numerics technique to study a cylindrically symmetric model of magnetic flux tubes in a dense lattice and the non-local Casimir forces acting between regions of magnetic flux. Within a superconductor the magnetic field is constrained ... More
Statistical ages and the cooling rate of X-ray dim isolated neutron starsMay 04 2013Aug 12 2013The cooling theory of neutron stars is corroborated by its comparison with observations of thermally emitting isolated neutron stars and accreting neutron stars in binary systems. An important ingredient for such an analysis is the age of the object, ... More
What is the nature of RX J0720.4-3125?Jan 06 1998RX J0720.4-3125 has recently been identified as a pulsating soft X-ray source in the ROSAT all-sky survey with a period of 8.391 s. Its spectrum is well characterized by a black-body with a temperature of $8 \times 10^5$ K. We propose that the radiation ... More
The Thermal Evolution of Ultramagnetized Neutron StarsOct 21 1997Using recently calculated analytic and numerical models for the thermal structure of ultramagnetized neutron stars, we estimate the effects that ultrastrong magnetic fields $B \ge 10^{14}$ G have on the thermal evolution of a neutron star. Understanding ... More
Dynamical Tide in Solar-Type BinariesJan 28 1998Circularization of late-type main-sequence binaries is usually attributed to turbulent convection, while that of early-type binaries is explained by resonant excitation of g modes. We show that the latter mechanism operates in solar-type stars also and ... More
Bulk measurement of copper and sodium content in CuIn(0.7)Ga(0.3)Se(2) (CIGS) solar cells with nanosecond pulse length laser induced breakdown spectroscopy (LIBS)Jan 07 2013In this work, we show that laser induced breakdown spectroscopy (LIBS) with a nanosecond pulse laser can be used to measure the copper and sodium content of CuIn(0.7)Ga(0.3)Se(2) (CIGS) thin film solar cells on molybdenum. This method has four significant ... More
An Analytic Form for the Effective Lagrangian of QED and its Application to Pair Production and Photon SplittingJul 15 1996We derive an analytic form for the Heisenberg-Euler Lagrangian in the limit where the component of the electric field parallel to the magnetic field is small. We expand these analytic functions to all orders in the field strength ($F_{\mu\nu}F^{\mu\nu}$) ... More
A QED Model for the Origin of Bursts from SGRs and AXPsDec 23 2003Aug 31 2004We propose a model to account for the bursts from soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) in which quantum electrodynamics (QED) plays a vital role. In our theory, that we term ``fast-mode breakdown,'' magnetohydrodynamic (MHD) ... More
RCW 103 -- Revisiting a cooling neutron starMay 07 1998Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object's emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence ... More
Nonlinear Electromagnetic Waves in Magnetosphere of a MagnetarFeb 15 2010Nov 10 2010We compute electromagnetic wave propagation through the magnetosphere of a magnetar. The magnetosphere is modeled as the QED vacuum and a cold, strongly magnetized plasma. The background field and electromagnetic waves are treated nonperturbatively and ... More
Polluting White Dwarfs with Perturbed Exo-CometsFeb 24 2017Apr 27 2017We present a model to account for the observed debris disks around young white dwarfs and the presence of metal-lines in their spectra. Stellar evolution models predict that the mass-loss on the AGB will be pulsed; furthermore, observations indicate that ... More
A Study of the Long-term Spectral Variations of 3C 66A Observed with the Fermi and Kanata TelescopesJan 12 20133C 66A is an intermediate-frequency-peaked BL Lac object detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. We present a study of the long-term variations of this blazar seen over 2 years at GeV energies with Fermi and in ... More
Variational study of the antiferromagnetic insulating phase of V2O3 based on Nth order Muffin-Tin-OrbitalsApr 17 2009Motivated by recent results of $N$th order muffin-tin orbital (NMTO) implementation of the density functional theory (DFT), we re-examine low-temperature ground-state properties of the anti-ferromagnetic insulating phase of vanadium sesquioxide V$_2$O$_3$. ... More
An effective spin-orbital Hamiltonian for the double perovskite Sr$_2$FeW O$_6$: Derivation of the phase diagramFeb 14 2003We formulate a superexchange theory of insulating double-perovskite compounds such as Sr$_2$FeWO$_6$. An effective spin-orbital Hamiltonian is derived in the strong coupling limit of Hubbard model for d-electrons on Fe and W ions. The relevant degrees ... More
Lichnerowicz Modes and Black Hole Families in Ricci Quadratic GravityApr 18 2017A new branch of black hole solutions occurs along with the standard Schwarzschild branch in $n$-dimensional extensions of general relativity including terms quadratic in the Ricci tensor. The standard and new branches cross at a point determined by a ... More
Spherically Symmetric Solutions in Higher-Derivative GravityJul 31 2015Dec 19 2015Extensions of Einstein gravity with quadratic curvature terms in the action arise in most effective theories of quantised gravity, including string theory. This article explores the set of static, spherically symmetric and asymptotically flat solutions ... More
Black Holes in Higher-Derivative GravityFeb 03 2015Apr 14 2015Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this paper we study static black-hole solutions in the example of Einstein gravity ... More
Potential for modulation of the hydrophobic effect inside chaperoninsFeb 05 2008Despite the spontaneity of some in vitro protein folding reactions, native folding in vivo often requires the participation of barrel-shaped multimeric complexes known as chaperonins. Although it has long been known that chaperonin substrates fold upon ... More
QED and the High Polarization of the Thermal Radiation from Neutron StarsMar 05 2002May 16 2002The thermal emission of strongly magnetized neutron-star atmospheres is thought to be highly polarized. However, because of the different orientations of the magnetic field over the surface of the neutron star (NS), it is commonly assumed that the net ... More
Trusted Certificates in Quantum CryptographyMar 10 2006This paper analyzes the performance of Kak's three stage quantum cryptographic protocol based on public key cryptography against a man-in-the-middle attack. A method for protecting against such an attack is presented using certificates distributed by ... More
Birthday Inequalities, Repulsion, and Hard SpheresJun 03 2015Nov 26 2015We study a birthday inequality in random geometric graphs: the probability of the empty graph is upper bounded by the product of the probabilities that each edge is absent. We show the birthday inequality holds at low densities, but does not hold in general. ... More
BFKL Pomeron calculus: nucleus-nucleus scatteringDec 19 2011In this paper the action of the BFKL Pomeron calculus is re-written in momentum representation, and the equations of motion for nucleus-nucleus collisions are derived, in this representation. We found the semi-classical solutions to these equations, outside ... More
The Influence of Triaxial Halos on Collisionless Galactic DisksSep 09 2002Sep 11 2002We investigate the effect of rotating, triaxial halos on disk galaxies through an extensive set of numerical N-body simulations. Our simulations use a rigid potential field for the halos and bulges and collisionless particles for the disks. The triaxiality ... More
Cosmic Rays from Pulsars and MagnetarsMay 06 2010We compare the expected abundance of cosmic-ray electrons and positrons from pulsars and magnetars. We assume that the distribution of infant pulsars and magnetars follows that of high-mass stars in the Milky Way and that the production rate of cosmic ... More
Polarization Evolution in Strong Magnetic FieldsSep 20 1999Extremely strong magnetic fields change the vacuum index of refraction. Although this polarization dependent effect is small for typical neutron stars, it is large enough to decouple the polarization states of photons traveling within the field. The photon ... More
The Near-IR Spectrum of Titan Modeled with an Improved Methane Line ListFeb 13 2011Feb 17 2011We have obtained spatially resolved spectra of Titan in the near-infrared J, H and K bands at a resolving power of ~5000 using the near-infrared integral field spectrometer (NIFS) on the Gemini North 8m telescope. Using recent data from the Cassini/Huygens ... More
Supermassive black holes at high redshiftsMar 14 2019MeV blazars are the most luminous persistent sources in the Universe and emit most of their energy in the MeV band. These objects display very large jet powers and accretion luminosities and are known to host black holes with a mass often exceeding $10^9 ... More
cltorch: a Hardware-Agnostic Backend for the Torch Deep Neural Network Library, Based on OpenCLJun 15 2016This paper presents cltorch, a hardware-agnostic backend for the Torch neural network framework. cltorch enables training of deep neural networks on GPUs from diverse hardware vendors, including AMD, NVIDIA, and Intel. cltorch contains sufficient implementation ... More
Random k-SAT and the Power of Two ChoicesSep 24 2012Oct 15 2013We study an Achlioptas-process version of the random k-SAT process: a bounded number of k-clauses are drawn uniformly at random at each step, and exactly one added to the growing formula according to a particular rule. We prove the existence of a rule ... More
The Dirichlet Problem for Harmonic Functions on Compact SetsApr 30 2010Jan 21 2011For any compact set $K\subset \mathbb{R}^n$ we develop the theory of Jensen measures and subharmonic peak points, which form the set $\mathcal{O}_K$, to study the Dirichlet problem on $K$. Initially we consider the space $h(K)$ of functions on $K$ which ... More
Robust adaptive droop control for DC microgridsJan 16 2017Jan 22 2017There are tradeoffs between current sharing among distributed resources and DC bus voltage stability when conventional droop control is used in DC microgrids. As current sharing approaches the setpoint, bus voltage deviation increases. Previous studies ... More
VERITAS Telescope 1 Relocation: Details and ImprovementsDec 18 2009The first VERITAS telescope was installed in 2002-2003 at the Fred Lawrence Whipple Observatory and was originally operated as a prototype instrument. Subsequently the decision was made to locate the full array at the same site, resulting in an asymmetric ... More
Doniach diagram for ordered, disordered and underscreened Kondo latticesAug 28 2007The Doniach's diagram has been originally proposed to describe the competition between the local Kondo effect and the intersite RKKY interactions in cerium compounds. Here we discuss the extension of this diagram to different variations of Kondo lattice ... More
Relaxation time of the global order parameter on multiplex networks: the role of interlayer coupling in Kuramoto oscillatorsAug 06 2017This work considers the timescales associated with the global order parameter and the interlayer synchronization of coupled Kuramoto oscillators on multiplexes. For the two-layer multiplexes with initially high degree of synchronization in each layer, ... More
Two-Component Fokker-Planck Models for the Evolution of Isolated Globular ClustersNov 11 1997Two-component (normal and degenerate stars) models are the simplest realization of clusters with a mass spectrum because high mass stars evolve quickly into degenerates, while low mass stars remain on the main-sequence for the age of the universe. Here ... More
The Early Evolution of Star Clusters in Compressive and Extensive Tidal FieldsFeb 10 2017We present N-body simulations of star clusters that initially evolve within a strong compressive tidal field and then transition into extensive tidal fields of varying strengths. While subject to compressive tides, clusters can undergo significant heating ... More
Experimentally Exploring the Interatomic Potential in a Ferroelectric Crystal via Optimal Ultrafast Lattice ControlJan 31 2017We present a direct comparison between resonant terahertz (THz) and nonresonant impulsive stimulated Raman scattering (ISRS) excitation of phonon-polaritons in ferroelectric lithium niobate. THz excitation offers advantages of selectively driving only ... More
The Sun's meridional circulation and interior magnetic fieldJun 26 2011To date, no self-consistent numerical simulation of the solar interior has succeeded in reproducing the observed thinness of the solar tachocline, and the persistence of uniform rotation beneath it. Although it is known that the uniform rotation can be ... More
Quantum Dot Cluster State Computing with Encoded QubitsJun 03 2005A class of architectures is advanced for cluster state quantum computation using quantum dots. These architectures include using single and multiple dots as logical qubits. Special attention is given to the supercoherent qubits introduced by Bacon, Brown, ... More
Cantor set arithmeticNov 23 2017Every element $u$ of $[0,1]$ can be written in the form $u=x^2y$, where $x,y$ are elements of the Cantor set $C$. In particular, every real number between zero and one is the product of three elements of the Cantor set. On the other hand the set of real ... More
Novel Graph Processor Architecture, Prototype System, and ResultsJul 22 2016Graph algorithms are increasingly used in applications that exploit large databases. However, conventional processor architectures are inadequate for handling the throughput and memory requirements of graph computation. Lincoln Laboratory's graph-processor ... More
Globular cluster absolute ages from cooling brown dwarfsFeb 01 2017Globular clusters are the oldest conglomerates of stars in our Galaxy and can be useful laboratories to test theories from stellar evolution to cosmology. In this paper, we present a new method to estimate the absolute age of a globular cluster from observations ... More
Magnetic Lensing near Ultramagnetized Neutron StarsJan 27 1999Extremely strong magnetic fields change the vacuum index of refraction. This induces a lensing effect that is not unlike the lensing phenomenon in strong gravitational fields. The main difference between the two is the polarization dependency of the magnetic ... More
Hierarchical Multi-scale Attention Networks for Action RecognitionAug 25 2017Aug 28 2017Recurrent Neural Networks (RNNs) have been widely used in natural language processing and computer vision. Among them, the Hierarchical Multi-scale RNN (HM-RNN), a kind of multi-scale hierarchical RNN proposed recently, can learn the hierarchical temporal ... More
CHAM: action recognition using convolutional hierarchical attention modelMay 09 2017May 19 2017Recently, the soft attention mechanism, which was originally proposed in language processing, has been applied in computer vision tasks like image captioning. This paper presents improvements to the soft attention model by combining a convolutional LSTM ... More
Optimized Multichannel Quantum Defect Theory for cold molecular collisionsJun 26 2012Multichannel quantum defect theory (MQDT) can provide an efficient alternative to full coupled-channel calculations for low-energy molecular collisions. However, the efficiency relies on interpolation of the Y matrix that encapsulates the short-range ... More
Cosmic Voids and Galaxy Bias in the Halo Occupation FrameworkMar 06 2006(Abridged) We investigate the power of void statistics to constrain galaxy bias and the amplitude of dark matter fluctuations. We use the halo occupation distribution (HOD) framework to describe the relation between galaxies and dark matter. After choosing ... More
Free Semidefinite Representation of Matrix Power FunctionsMay 18 2013Oct 09 2014Consider the matrix power function X^p defined over the cone of positive definite matrices S^{n}_{++}. It is known that X^p is convex over S^{n}_{++} if p is in [-1,0] or [1,2] and X^p is concave over S^{n}_{++} if p is in [0,1]. We show that the hypograph ... More
Topological and algebraic pullback functorsMay 14 2012We give algebraic equivalents for certain desirable properties of pullback functors on categories of coverings and group sets, namely nullity zero, essential injectivity, and essential surjectivity. Nullity zero turns out to be equivalent to the notion ... More
Pathwise uniqueness for stochastic heat equations with Hölder continuous coefficients: the white noise caseSep 01 2008We prove pathwise uniqueness for solutions of parabolic stochastic pde's with multiplicative white noise if the coefficient is H\"older continuous of index $\gamma>3/4$. The method of proof is an infinite-dimensional version of the Yamada-Watanabe argument ... More
Spectral Thresholds in the Bipartite Stochastic Block ModelJun 22 2015May 24 2016We consider a bipartite stochastic block model on vertex sets $V_1$ and $V_2$, with planted partitions in each, and ask at what densities efficient algorithms can recover the partition of the smaller vertex set. When $|V_2| \gg |V_1|$, multiple thresholds ... More
Composite Photon Theory Versus Elementary Photon TheoryMar 02 2015The purpose of this paper is to show that the composite photon theory measures up well against the Standard Model's elementary photon theory. This is done by comparing the two theories area by area. Although the predictions of quantum electrodynamics ... More
The Antiparticles of Neutral BosonsNov 15 2013With the advent of the ability to create and study antihydrogen, we think it is appropriate to consider the possibility that antiphotons might not be identical to photons. First of all, we will look at the experimental evidence concerning multiple neutral ... More
The p-bar p --> pi_0 pi_0 PuzzleNov 02 1999According to conventional theory, the annihilation reaction p-bar p --> pi_0 pi_0 cannot occur from a p-bar p atomic S state. However, this reaction occurs so readily for antiprotons stopping in liquid hydrogen, that it would require 30% P-wave annihilations. ... More
Colliding Bubble WorldsOct 13 2000We consider a cosmological model in which our Universe is a spherically symmetric bubble wall in 5-dimensional anti-de Sitter spacetime. We argue that the bubble on which we live will undergo collisions with other similar bubbles and estimate the spectrum ... More
On twisted $A$-harmonic sums and Carlitz finite zeta valuesDec 18 2015Jun 16 2016In this paper, we study various twisted A-harmonic sums, named following the seminal log-algebraicity papers of G. Anderson. These objects are partial sums of new types of special zeta values introduced by the first author and linked to certain rank one ... More
Study of the acoustic signature of UHE neutrino interactions in water and iceMar 05 2009Mar 10 2009The production of acoustic signals from the interactions of ultra-high energy (UHE) cosmic ray neutrinos in water and ice has been studied. A new computationally fast and efficient method of deriving the signal is presented. This method allows the implementation ... More
Aspects of classical backgrounds and scattering for affine Toda theory on a half-lineSep 23 1999In this paper we study various aspects of classical solutions to the affine Toda equations on a half-line with integrable boundary conditions. We begin by finding conditions that the theory has a stable vacuum by finding a Bogomolny bound on the energy, ... More
Probing Screening and the Graviton Mass with Gravitational WavesNov 06 2018Gravitational waves can probe fundamental physics, leading to new constraints on the mass of the graviton. Previous tests, however, have neglected the effect of screening, which is typically present in modified theories that predict a non-zero graviton ... More
On Pellarin's $L$-seriesDec 29 2011Nov 02 2012Necessary and sufficient conditions are given for a negative integer to be a trivial zero of a new type of $L$-series recently discovered by F. Pellarin, and it is shown that any such trivial zero is simple. We determine the exact degree of the special ... More
An exact degree for multivariate special polynomialsFeb 17 2014We introduce certain special polynomials in an arbitrary number of indeterminates over a finite field. These polynomials generalize the special polynomials associated to the Goss zeta function and Goss-Dirichlet $L$-functions over the ring of polynomials ... More
Blue-Green Emission from Epitaxial Yet Cation-Disordered ZnGeN$_{2-x}$O$_x$Apr 26 2019ZnGeN$_2$ offers a low-cost alternative to InGaN with the potential for bandgap tuning to span the green gap using cation site ordering. The addition of oxygen on the anion site creates an additional degree of electronic tunability. Here, we investigate ... More
Markov chain approach to anomalous diffusion on Newman-Watts networksJan 31 2019Feb 26 2019A Markov chain (MC) formalism is used to investigate the mean-square displacement (MSD) of a random walker on Newman-Watts (NW) networks. It leads to a precise analysis of the conditions for the emergence of anomalous sub- or super-diffusive regimes in ... More
Super-conducting critical fields and anisotropy of a MgB2 single crystalMay 02 2002May 07 2002Despite the intense activity in the year since the discovery of superconductivity in MgB2, key parameters, in particular the upper and lower critical fields Hc2 and Hc1 and their anisotropies, are not well-established, largely because of the difficulty ... More
Raman scattering in a Heisenberg {\boldmath $S=1/2$} antiferromagnet on the triangular latticeMar 02 2008We investigate two-magnon Raman scattering from the $S=1/2$ Heisenberg antiferromagnet on the triangular lattice, considering both the effect of renormalization of the one-magnon spectrum by 1/S corrections and final-state magnon-magnon interactions. ... More
Helicity Zero ParticlesSep 14 2004In this paper we consider the possibility that a vector particle with mass might exist in only one helicity state, rather than the usual three states with helicity equal to +1, -1, and 0. Massless particles, of course, need only have one helicity state. ... More
A lower bound for $p_c$ in range-$R$ bond percolation in two and three dimensionsMar 14 2016We use the connection between bond percolation and SIR epidemics to establish lower bounds for the critical percolation probability in $2$ and $3$ dimensions as the range becomes large. The bound agrees with the conjectured asymptotics for the long range ... More
Convex and subharmonic functions on graphsApr 01 2013We explore the relationship between convex and subharmonic functions on discrete sets. Our principal concern is to determine the setting in which a convex function is necessarily subharmonic. We initially consider the primary notions of convexity on graphs ... More
Extinction for two parabolic stochastic PDE's on the latticeMar 16 1999Dec 31 2001It is well known that, starting with finite mass, the super-Brownian motion dies out in finite time. The goal of this article is to show that with some additional work, one can prove finite time die-out for two types of systems of stochastic differential ... More
Explicit Formulae for $L$-values in Positive CharacteristicJul 07 2012Apr 30 2014We focus on the generating series for the rational special values of Pellarin's $L$-series in $1 \leq s \leq 2(q-1)$ indeterminates, and using interpolation polynomials we prove a closed form formula relating this generating series to the Carlitz exponential, ... More
Stringent Phenomenological Investigation into Heterotic String Optical UnificationOct 11 2005For the weakly coupled heterotic string (WCHS) there is a well-known factor of twenty conflict between the minimum string coupling unification scale, Lambda_H ~5x10^(17) GeV, and the projected MSSM unification scale, Lambda_U ~ 2.5x10^(16) GeV, assuming ... More
Green functions, the fine topology and restoring coveringsDec 17 2010There are several equivalent ways to define continuous harmonic functions $H(K)$ on a compact set $K$ in $\mathbb R^n$. One may let $H(K)$ be the unform closures of all functions in $C(K)$ which are restrictions of harmonic functions on a neighborhood ... More
Weak convergence of measure-valued processes and $r$-point functionsOct 16 2007We prove a sufficient set of conditions for a sequence of finite measures on the space of cadlag measure-valued paths to converge to the canonical measure of super-Brownian motion in the sense of convergence of finite-dimensional distributions. The conditions ... More
The dimension of the boundary of super-Brownian motionNov 09 2017We show that the Hausdorff dimension of the boundary of $d$-dimensional super-Brownian motion is $0$, if $d=1$, $4-2\sqrt2$, if $d=2$, and $(9-\sqrt{17})/2$, if $d=3$.
Nanoconfined ionic liquids: disentangling electrostatic & viscous forcesJan 03 2018Recent reports of surface forces across nanoconfined ionic liquids have revealed the existence of an anomalously long-ranged interaction apparently of electrostatic origin. Ionic liquids are viscous and therefore it is important to inspect rigorously ... More
The RAPTOR Experiment: A System for Monitoring the Optical Sky in Real TimeSep 16 2002The Rapid Telescopes for Optical Response (RAPTOR) experiment is a spatially distributed system of autonomous robotic telescopes that is designed to monitor the sky for optical transients. The core of the system is composed of two telescope arrays, separated ... More
Long-Term Multiwavelength Studies of High-Redshift Blazar 0836+710Jul 01 2013Aims. The observation of gamma -ray flares from blazar 0836+710 in 2011, following a period of quiescence, offered an opportunity to study correlated activity at different wavelengths for a high-redshift (z=2.218) active galactic nucleus. Methods. Optical ... More
Galaxy Formation in a Variety of Hierarchical ModelsAug 18 1994We predict the observable properties of the galaxy population in popular hierarchical models of galaxy formation. We employ a detailed semianalytic procedure which incorporates the formation and merging of dark matter halos, the shock heating and radiative ... More
Low momentum shell model effective interactions with all-order core polarizationsApr 18 2005An all-order summation of core polarization diagrams using the low-momentum nucleon-nucleon interaction, V_low-k is presented. The summation is based on the Kirson-Babu-Brown (KBB) induced interaction approach in which the vertex functions are obtained ... More
The MERger-event Gamma-Ray (MERGR) TelescopeNov 09 2017We describe the MERger-event Gamma-Ray (MERGR) Telescope intended for deployment by ~2021. MERGR will cover from 20 keV to 2 MeV with a wide field of view (6 sr) using nineteen gamma-ray detectors arranged on a section of a sphere. The telescope will ... More
Modeling of Cables with High and Low Tension Zones using a Hybrid Rod-Catenary FormulationFeb 25 2007Cables under very low tension may become highly contorted and form loops, tangles, knots and kinks. These nonlinear deformations, which are dominated by flexure and torsion, pose serious concerns for cable deployment. Simulation of the three-dimensional ... More
Nonlinear dynamic strand model with coupled tension and torsionFeb 23 2007We simulate the nonlinear dynamic responses in Kirchhoff rod by including the important effects due to inertia and kinematic coupling of tension and torsion. We begin by reviewing a dynamic rod model of a strand (length of cable or DNA) in the form of ... More
Spin systems on Bethe latticesAug 10 2018In an extremely influential paper Mezard and Parisi put forward an analytic but non-rigorous approach called the cavity method for studying spin systems on the Bethe lattice, i.e., the random $d$-regular graph [Eur. Phys. J. B 20 (2001) 217--233]. Their ... More
Surface forces generated by the action of electric fields across liquid filmsApr 07 2019We explore the force generation and surface interactions arising when electric fields are applied across fluid films. Using a surface force balance (SFB) we measure directly the force between two electrodes in crossed-cylinder geometry across dielectric ... More
Diffusion in jammed particle packsJul 31 2015Using random walk simulations we explore diffusive transport through monodisperse sphere packings over a range of packing fractions, $\phi$, in the vicinity of the jamming transition at $\phi_{c}$. Various diffusion properties are computed over several ... More
Structural Modeling of DNA Loops in Lactose-RepressorFeb 23 2007It is well known that the structural deformations (stressed states) of DNA molecule play a crucial role in its biological functions including gene expression. For instance, looping in DNA (often mediated by protein binding) is a crucial step in many gene ... More
Radio scintillation of gamma-ray-burst afterglowsJun 09 1997Stars twinkle to the eye through atmospheric turbulence, but planets, because of their larger angular size, do not. Similarly, scintillation due to the local interstellar medium will modulate the radio flux of gamma-ray-burst afterglows and may permit ... More
Hadron Structure from Lattice QCDDec 15 2014Recent progress in lattice QCD calculations of nucleon structure will be presented. Calculations of nucleon matrix elements and form factors have long been difficult to reconcile with experiment, but with advances in both methodology and computing resources, ... More
Nilpotence in E_n AlgebrasJul 04 2017Nilpotence in the homotopy of $\mathbb{E}_\infty$-ring spectra is detected by the classical $H\mathbb{Z}$-Hurewicz homomorphism. Inspired by questions of Mathew, Noel, and Naumann, we investigate the extent to which this criterion holds in the homotopy ... More
Deformations of vector bundles on coisotropic subvarieties via the Atiyah classOct 18 2010Using the Atiyah class we give a criterion for a vector bundle on a coisotropic subvariety, $Y$, of an algebraic Poisson variety $X$ to admit a first and second order noncommutative deformation. We also show noncommutative deformations of a vector bundle ... More
A Formaldehyde Deep FieldMar 28 2019Formaldehyde (H2CO) is often observed at centimeter wavelengths as an absorption line against the cosmic microwave background (CMB). This is possible when energy level populations are cooled to the point where line excitation temperatures fall below the ... More
Testing Gravity Using Dwarf StarsNov 05 2015Dec 08 2017Generic scalar-tensor theories of gravity predict deviations from Newtonian physics inside astrophysical bodies. In this paper, we point out that low mass stellar objects, red and brown dwarf stars, are excellent probes of these theories. We calculate ... More
Generalized covering space theoriesAug 20 2015In this paper, we unify various approaches to generalized covering space theory by introducing a categorical framework in which coverings are defined purely in terms of unique lifting properties. For each category $\mathcal{C}$ of path-connected spaces ... More
Quadratic forms representing all odd positive integersNov 03 2011Nov 06 2013We consider the problem of classifying all positive-definite integer-valued quadratic forms that represent all positive odd integers. Kaplansky considered this problem for ternary forms, giving a list of 23 candidates, and proving that 19 of those represent ... More
Stability and bifurcation of equilibria for the axisymmetric averaged mean curvature flowNov 08 2012Nov 09 2012We study the averaged mean curvature flow, also called the volume preserving mean curvature flow, in the particular setting of axisymmetric surfaces embedded in R^3 satisfying periodic boundary conditions. We establish analytic well--posedness of the ... More
Equivalences of derived categories for symmetric algebrasJan 08 2002We give a characterization of the sets of objects of the derived category of a block of a finite group algebra (or other symmetric algebra) that occur as the set of images of simple modules under an equivalence of derived categories. We give some applications ... More