Results for "Douglas P. Hamilton"

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Implications of the PSR 1257+12 Planetary System for Isolated Millisecond PulsarsDec 02 2000The first extrasolar planets were discovered in 1992 around the millisecond pulsar PSR 1257+12. We show that recent developments in the study of accretion onto magnetized stars, plus the existence of the innermost, moon-sized planet in the PSR 1257+12 ... More
Secular Orbital Evolution of Compact Planet SystemsFeb 07 2013Oct 24 2013Recent observations have shown that at least some close-in exoplanets maintain eccentric orbits despite tidal circularization timescales that are typically shorter than stellar ages. We explore gravitational interactions with a distant planetary companion ... More
Yarkovsky-Driven Spreading of the Eureka Family of Mars TrojansDec 04 2014Out of nine known stable Mars Trojans, seven appear to be members of an orbital grouping including the largest Trojan, Eureka. In order to test if this could be a genetic family, we simulated the long term evolution of a tight orbital cluster centered ... More
Three-Body Dynamics with Gravitational Wave EmissionSep 29 2005Nov 21 2005We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading order terms of energy loss from gravitational ... More
Three-Body Encounters of Black Holes in Globular ClustersJun 10 2003Jul 01 2003Evidence has been mounting for the existence of black holes with masses from 10^2 to 10^4 M_Solar associated with stellar clusters. Such intermediate-mass black holes (IMBHs) will encounter other black holes in the dense cores of these clusters. The binaries ... More
Three-Body Capture of Irregular Satellites: Application to JupiterNov 06 2009We investigate a new theory of the origin of the irregular satellites of the giant planets: capture of one member of a ~100-km binary asteroid after tidal disruption. The energy loss from disruption is sufficient for capture, but it cannot deliver the ... More
Galileo In-Situ Dust Measurements in Jupiter's Gossamer RingsMar 19 2008During its late orbital mission at Jupiter the Galileo spacecraft made two passages through the giant planet's gossamer ring system. The impact-ionization dust detector on board successfully recorded dust impacts during both ring passages and provided ... More
Chaotic dust dynamics and implications for the hemispherical color asymmetries of the Uranian satellitesJun 17 2013Dust grains generated by the Uranian irregular satellites will undergo chaotic large-amplitude eccentricity oscillations under the simultaneous action of radiation forces and the highly misaligned quadrupole potentials of the oblate planet and distant ... More
Tidal evolution of the Moon from a high-obliquity, high-angular-momentum EarthFeb 09 2018In the giant impact hypothesis for lunar origin, the Moon accreted from an equatorial circum-terrestrial disk; however the current lunar orbital inclination of 5 degrees requires a subsequent dynamical process that is still debated. In addition, the giant ... More
Radial profiles of the Phoebe ring, a vast debris disk around SaturnApr 11 2016We present observations at optical wavelengths with the Cassini Spacecraft's Imaging Science System of the Phoebe ring, a vast debris disk around Saturn that seems to be collisionally generated by its irregular satellites. The analysis reveals a radial ... More
Finding the trigger to Iapetus' odd global albedo pattern: Dynamics of dust from Saturn's irregular satellitesJun 09 2011The leading face of Saturn's moon Iapetus, Cassini Regio, has an albedo only one tenth that on its trailing side. The origin of this enigmatic dichotomy has been debated for over forty years, but with new data, a clearer picture is emerging. Motivated ... More
The Role of the Kozai-Lidov Mechanism in Black Hole Binary Mergers in Galactic CentersApr 18 2016In order to understand the rate of merger of stellar-mass black hole binaries (BHBs) by gravitational wave (GW) emission it is important to determine the major pathways to merger. We use numerical simulations to explore the evolution of BHBs inside the ... More
Dynamical Instabilities in High-Obliquity SystemsNov 30 2012High-inclination circumplanetary orbits that are gravitationally perturbed by the central star can undergo Kozai oscillations---large-amplitude, coupled variations in the orbital eccentricity and inclination. We first study how this effect is modified ... More
Binary Encounters With Supermassive Black Holes: Zero-Eccentricity LISA EventsJul 06 2005Sep 30 2005Current simulations of the rate at which stellar-mass compact objects merge with supermassive black holes (called extreme mass ratio inspirals, or EMRIs) focus on two-body capture by emission of gravitational radiation. The gravitational wave signal of ... More
Mass Segregation in NGC 2298: limits on the presence of an Intermediate Mass Black HoleApr 21 2009[abridged] Theoretical investigations have suggested the presence of Intermediate Mass Black Holes (IMBHs, with masses in the 100-10000 Msun range) in the cores of some Globular Clusters (GCs). In this paper we present the first application of a new technique ... More
Rotation sensing with trapped ionsSep 02 2016We present a protocol for using trapped ions to measure rotations via matter-wave Sagnac interferometry. The trap allows the interferometer to enclose a large area in a compact apparatus through repeated round-trips in a Sagnac geometry. We show how a ... More
Microwave ISM Emission Observed by WMAPNov 24 2003Dec 13 2003We investigate the nature of the diffuse Galactic emission in the Wilkinson Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial dust-correlated emission is observed at all WMAP frequencies, far exceeding the expected thermal dust ... More
Observing Planetary Rings with JWST: Science Justification and Observation RequirementsMar 26 2014Oct 22 2015The James Webb Space Telescope (JWST) will provide unprecedented opportunities to observe the rings and small satellites in our solar system, accomplishing three primary objectives: 1) discovering new rings and moons, 2) unprecedented spectroscopy, and ... More
Fisher Information and Kinetic-energy Functionals: A Dequantization ApproachMay 21 2009We strengthen the connection between Information Theory and quantum-mechanical systems using a recently developed dequantization procedure whereby quantum fluctuations latent in the quantum momentum are suppressed. The dequantization procedure results ... More
Herschel Observations of Cataclysmic VariablesNov 20 2012We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 microns. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE ... More
Intermediate Mass Black Hole Induced Quenching of Mass Segregation in Star ClustersJun 25 2008In many theoretical scenarios it is expected that intermediate-mass black holes (IMBHs, with masses M ~ 100-10000 solar masses) reside at the centers of some globular clusters. However, observational evidence for their existence is limited. Several previous ... More
Exponential decay of connectivity and uniqueness in percolation on finite and infinite graphsOct 16 2016We give an upper bound for the uniqueness transition on an arbitrary locally finite graph ${\cal G}$ in terms of the limit of the spectral radii $\rho\left[ H({\cal G}_t)\right]$ of the non-backtracking (Hashimoto) matrices for an increasing sequence ... More
Proceedings of the Fourth International Workshop on Verification and Program TransformationJul 06 2016This volume contains the revised versions of papers presented at the Fourth International Workshop on Verification and Program Transformation (VPT 2016) on April 2, 2016 in Eindhoven, The Netherlands. The workshop is an event of the European Joint Conferences ... More
The river model of black holesNov 12 2004Aug 31 2006This paper presents an under-appreciated way to conceptualize stationary black holes, which we call the river model. The river model is mathematically sound, yet simple enough that the basic picture can be understood by non-experts. %that can by understood ... More
The physics of the relativistic counter-streaming instability that drives mass inflation inside black holesNov 12 2008Jun 15 2010If you fall into a real astronomical black hole (choosing a supermassive black hole, to make sure that the tidal forces don't get you first), then you will probably meet your fate not at a central singularity, but rather in the exponentially growing, ... More
Detecting Dark Matter Annihilation with CMB Polarization : Signatures and Experimental ProspectsMar 23 2005Dark matter (DM) annihilation during hydrogen recombination (z ~ 1000) will alter the recombination history of the Universe, and affect the observed CMB temperature and polarization fluctuations. Unlike other astrophysical probes of DM, this is free of ... More
How Many Universes Do There Need To Be?May 29 2006Mar 19 2007In the simplest cosmological models consistent with General Relativity, the total volume of the Universe is either finite or infinite, depending on whether or not the spatial curvature is positive. Current data suggest that the curvature is very close ... More
Strong Evidence for Gamma-ray Line Emission from the Inner GalaxyJun 07 2012Jun 14 2012Using 3.7 years of \Fermi-LAT data, we examine the diffuse 80-200 GeV emission in the inner Galaxy and find a resolved gamma-ray feature at $\sim 110-140$ GeV. We model the spatial distribution of this emission with a $\sim3\degree$ FWHM Gaussian, finding ... More
Voltage-Induced Buckling of Dielectric Films using Fluid ElectrodesJan 12 2016Accurate and integrable control of different flows within microfluidic channels is crucial to further development of lab-on-a-chip and fully integrated adaptable structures. Here we introduce a flexible microactuator that buckles at a high deformation ... More
The random members of a $Π^0_1$ classNov 17 2016We examine several notions of randomness for elements in a given $\Pi^0_1$ class $\mathcal{P}$. Such an effectively closed subset $\mathcal{P}$ of $2^\omega$ may be viewed as the set of infinite paths through the tree $T_{\mathcal{P}}$ of extendible nodes ... More
Model-Robust Designs for Quantile RegressionMar 07 2014Sep 16 2014We give methods for the construction of designs for linear models, when the purpose of the investigation is the estimation of the conditional quantile function and the estimation method is quantile regression. The designs are robust against misspecified ... More
An X-Ray Line from eXciting Dark MatterFeb 26 2014Mar 03 2014The eXciting Dark Matter (XDM) model was proposed as a mechanism to efficiently convert the kinetic energy (in sufficiently hot environments) of dark matter into e+e- pairs. The standard scenario invokes a doublet of nearly degenerate DM states, and a ... More
The Real Message in the SkyNov 15 2005A recent paper by Hsu & Zee (physics/0510102) suggests that if a Creator wanted to leave a message for us, and she wanted it to be decipherable to all sentient beings, then she would place it on the most cosmic of all billboards, the Cosmic Microwave ... More
Extended Anomalous Foreground Emission in the WMAP 3-Year DataDec 06 2007We study the spectral and morphological characteristics of the diffuse Galactic emission in the WMAP temperature data using a template-based multi-linear regression, and obtain the following results. 1. We confirm previous observations of a bump in the ... More
Algorithmically random functions and effective capacitiesMar 21 2015We continue the investigation of algorithmically random functions and closed sets, and in particular the connection with the notion of capacity. We study notions of random continuous functions given in terms of a family of computable measures called symmetric ... More
Exciting Dark Matter and the INTEGRAL/SPI 511 keV signalFeb 21 2007May 10 2007We propose a WIMP candidate with an ``excited state'' 1-2 MeV above the ground state, which may be collisionally excited and de-excites by e+e- pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction ... More
Magnetic Inelastic Dark Matter: Directional Signals Without a Directional DetectorNov 12 2010Apr 13 2011The magnetic inelastic dark matter (MiDM) model, in which dark matter inelastically scatters off nuclei through a magnetic dipole interaction, has previously been shown to reconcile the DAMA/LIBRA annual modulation signal with null results from other ... More
Non-extensive diffusion entropy analysis: non-stationarity in teen birth phenomenaMay 24 2002A complex process is often a balance between non-stationary and stationary components. We show how the non-extensive Tsallis q-entropy indicator may be interpreted as a measure of non-stationarity in time series. This is done by applying the non-extensive ... More
Classical kinetic energy, quantum fluctuation terms and kinetic-energy functionalsSep 17 2006Apr 08 2007We employ a recently formulated dequantization procedure to obtain an exact expression for the kinetic energy which is applicable to all kinetic-energy functionals. We express the kinetic energy of an N-electron system as the sum of an N-electron classical ... More
A high resolution UV absorption spectrum of supernova ejecta in SN1006Feb 25 2006We report a high resolution, far-ultraviolet, STIS E140M spectrum of the strong, broad Si II, III, and IV features produced by the ejecta of SN1006 seen in absorption against the background Schweizer-Middleditch star. The spectrum confirms the extreme ... More
An Improved Process for Fabricating High-Mobility Organic Molecular Crystal Field-Effect TransistorsJun 21 2007In this paper we present an improved process for producing elastomer transistor stamps and high-mobility organic field-effect transistors (FETs) based on semiconducting acene molecular crystals. In particular, we have removed the need to use a silanized ... More
Preparation and detection of states with simultaneous spin alignment and molecular orientation in PbOJul 30 2008We are pursuing an experiment to measure the electric dipole moment of the electron using the molecule PbO. This measurement requires the ability to prepare quantum states with orientation of the molecular axis and, simultaneously, alignment of the electron ... More
The Fate of Sub-Micron Circumplanetary Dust Grains I: Aligned Dipolar Magnetic FieldsJan 17 2012We study the stability of charged dust grains orbiting a planet and subject to gravity and the electromagnetic force. Our numerical models cover a broad range of launch distances from the planetary surface to beyond synchronous orbit, and the full range ... More
Variational approach to dequantizationNov 08 2005Mar 28 2006We present a dequantization procedure based on a variational approach whereby quantum fluctuations latent in the quantum momentum are suppressed. This is done by adding generic local deformations to the quantum momentum operator which give rise to a deformed ... More
On the origin of the Trojan asteroids: Effects of Jupiter's mass accretion and radial migrationJul 19 2000We present analytic and numerical results which illustrate the effects of Jupiter's accretion of nebular gas and the planet's radial migration on its Trojan companions. Initially, we approximate the system by the planar circular restricted three-body ... More
Four-Body Effects in Globular Cluster Black Hole CoalescenceFeb 15 2002In the high density cores of globular clusters, multibody interactions are expected to be common, with the result that black holes in binaries are hardened by interactions. It was shown by Sigurdsson & Hernquist (1993) and others that 10 solar mass black ... More
The Fate of Sub-micron Circumplanetary Dust Grains II: Multipolar FieldsJun 05 2012We study the radial and vertical stability of dust grains launched with all charge-to-mass ratios at arbitrary distances from rotating planets with complex magnetic fields. We show that the aligned dipole magnetic field model analyzed by Jontof-Hutter ... More
Production of Intermediate-Mass Black Holes in Globular ClustersJun 11 2001The discovery of numerous non-nuclear X-ray point sources with luminosities L>10^39 erg/s in several starburst galaxies has stimulated speculation about their nature and origin. The strong variability seen in several sources points to massive black holes ... More
The New Horizons and Hubble Space Telescope Search For Rings, Dust, and Debris in the Pluto-Charon SystemSep 23 2017We searched for dust or debris rings in the Pluto-Charon system before, during, and after the New Horizons encounter. Methodologies included searching for back-scattered light during the approach to Pluto (phase $\sim15^\circ$), in situ detection of impacting ... More
Evidence Of Dark Matter Annihilations In The WMAP HazeMay 24 2007The WMAP experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. It has been suggested that this signal, known as the ``WMAP Haze'', could be synchrotron emission from relativistic electrons and positrons ... More
Coupling M2-branes to background fieldsApr 28 2011We discuss some of the issues arising in trying to extend the ABJM action to include couplings to background fields. This is analogous to the Myers-Chern-Simons terms of the multiple Dp-brane action. We review and extend previous results to include terms ... More
Backreaction and the Parametric Resonance of Cosmological FluctuationsJul 20 2000We study the class of two-field inflationary Universe models \lambda\phi^4/4 + g^2\chi^2\phi^2/2, in which parametric resonance during the initial stages of reheating can lead to an exponential amplification of the amplitude of cosmological fluctuations. ... More
A short proof that ``proper = unit''Nov 06 1998A short proof is given that the graphs with proper interval representations are the same as the graphs with unit interval representations.
No evidence for anomalously low variance circles on the skyDec 06 2010Apr 07 2011In a recent paper, Gurzadyan & Penrose claim to have found directions on the sky centred on which are circles of anomalously low variance in the cosmic microwave background (CMB). These features are presented as evidence for a particular picture of the ... More
Observing the evolution of the CMBSep 26 2007Most cosmological parameters are expected to change significantly only on cosmological time scales, but given the large amount of information contained within the Cosmic Microwave Background (CMB) sky, we can expect that changes in the CMB should be observable ... More
Precision cosmology defeats void models for accelerationJul 21 2010Mar 24 2011The suggestion that we occupy a privileged position near the centre of a large, nonlinear, and nearly spherical void has recently attracted much attention as an alternative to dark energy. Putting aside the philosophical problems with this scenario, we ... More
Gravity waves goodbyeApr 18 1999The detection of a stochastic background of long-wavelength gravitational waves (tensors) in the cosmic microwave background (CMB) anisotropy would be an invaluable probe of the high energy physics of the early universe. Unfortunately a combination of ... More
The Electron Injection Spectrum Determined by Anomalous Excesses in Cosmic Ray, Gamma Ray, and Microwave SignalsApr 07 2010Sep 13 2010Recent cosmic ray, gamma ray, and microwave signals observed by Fermi, PAMELA, and WMAP indicate an unexpected primary source of e+e- at 10-1000 GeV. We fit these data to "standard backgrounds" plus a new source, assumed to be a separable function of ... More
Spanning Trees in 2-treesJul 20 2016A spanning tree of a graph $G$ is a connected acyclic spanning subgraph of $G$. We consider enumeration of spanning trees when $G$ is a $2$-tree, meaning that $G$ is obtained from one edge by iteratively adding a vertex whose neighborhood consists of ... More
CMB and 21-cm Signals for Dark Matter with a Long-Lived Excited StateMay 23 2008Aug 16 2008Motivated by the eXciting Dark Matter (XDM) model of Finkbeiner & Weiner, hypothesized to explain the 511 keV signal in the center of the Milky Way, we consider the CMB and 21-cm signatures of models of dark matter with collisional long-lived excited ... More
Inelastic Dark Matter and DAMA/LIBRA: An Experimentum CrucisJun 01 2009Sep 13 2010The DAMA/LIBRA collaboration has detected an annual modulation of the recoil rate in NaI crystals with the phase expected for WIMP scattering events. This signal is dramatically inconsistent with upper limits from other experiments for elastically scattering ... More
The Dark Side of Galaxy ColorApr 19 2013Jul 22 2013We present age distribution matching, a theoretical formalism for predicting how galaxies of luminosity L and color C occupy dark matter halos. Our model supposes that there are just two fundamental properties of a halo that determine the color and brightness ... More
A statistical test of emission from unresolved point sourcesOct 05 2009May 10 2010We describe a simple test of the spatial uniformity of an ensemble of discrete events. Given an estimate for the point source luminosity function and an instrumental point spread function (PSF), a robust upper bound on the fractional point source contribution ... More
The low energy dynamics of charge two dyonic instantonsOct 11 2012Nov 16 2012We explore the low energy dynamics of charge two instantons and dyonic instantons in SU(2) 5-dimensional Yang-Mills. We make use of the moduli space approximation and first calculate the moduli space metric for two instantons. For dyonic instantons the ... More
Real event detection and the treatment of congestive heart failure: an e fficient technique to help cardiologists to make crucial decisionsSep 02 2002Using a method of entropic analysis of time series we establish the correlation between heartbeat long-range memory and mortality risk in patients with congestive heart failure.
The GZK Bound and Strong Neutrino-Nucleon Interactions above 10^19eV: a Progress ReportAug 15 2000Cosmic ray events above 10^19 eV have posed a fundamental problem for more than thirty years. Recent measurements indicate that these events do not show the features predicted by the GZK bound. The events may, in addition, display angular correlations ... More
Extra dimensions and Strong Neutrino-Nucleon interactions above $10^{19}$ eV : Breaking the GZK BarrierJan 05 2000May 19 2000Cosmic ray events above $10^{20}$ eV are on the verge of confronting fundamental particle physics. The neutrino is the only candidate primary among established particles capable of crossing 100 Mpc intergalactic distances unimpeded. The magnitude of $\nu ... More
Geometry and Mechanics of Thin Growing BilayersSep 17 2015Oct 29 2015We investigate how thin sheets of arbitrary shapes morph under the isotropic in-plane expansion of their top surface, which may represent several stimuli such as nonuniform heating, local swelling and differential growth. Inspired by geometry, an analytical ... More
A study of transport suppression in an undoped AlGaAs/GaAs quantum dot single-electron transistorOct 18 2013We report a study of transport blockade features in a quantum dot single-electron transistor, based on an undoped AlGaAs/GaAs heterostructure. We observe suppression of transport through the ground state of the dot, as well as negative differential conductance ... More
Little change in the sizes of the most massive galaxies since z = 1Jan 24 2011Recent reports suggest that elliptical galaxies have increased their size dramatically over the last ~8 Gyr. This result points to a major re-think of the processes dominating the latetime evolution of galaxies. In this paper we present the first estimates ... More
The ATLAS Trigger System Commissioning and PerformanceSep 30 2010Oct 07 2010The ATLAS trigger has been used very successfully to collect collision data during 2009 and 2010 LHC running at centre of mass energies of 900 GeV, 2.36 TeV, and 7 TeV. This paper presents the ongoing work to commission the ATLAS trigger with proton collisions, ... More
Classes on the moduli space of Riemann surfaces through a noncommutative Batalin-Vilkovisky formalismApr 22 2011Using the machinery of the Batalin-Vilkovisky formalism, we construct cohomology classes on compactifications of the moduli space of Riemann surfaces from the data of a contractible differential graded Frobenius algebra. We describe how evaluating these ... More
Piezoelectric rotator for studying quantum effects in semiconductor nanostructures at high magnetic fields and low temperaturesSep 14 2010We report the design and development of a piezoelectric sample rotation system, and its integration into an Oxford Instruments Kelvinox 100 dilution refrigerator, for orientation-dependent studies of quantum transport in semiconductor nanodevices at millikelvin ... More
AlGaAs/GaAs single electron transistors fabricated without modulation dopingMar 01 2010We have fabricated quantum dot single electron transistors, based on AlGaAs/GaAs heterojunctions without modulation doping, which exhibit clear and stable Coulomb blockade oscillations. The temperature dependence of the Coulomb blockade peak lineshape ... More
Mass Inflation in Brans-Dicke gravityApr 17 2009A detailed non-linear analysis of the internal structure of spherical, charged black holes that are accreting scalar matter is performed in the framework of the Brans-Dicke theory of gravity. We choose the lowest value of the Brans-Dicke parameter that ... More
Mass inflation in a D dimensional Reissner-Nordstrom black hole: a hierarchy of particle accelerators ?May 23 2011We study the geometry inside the event horizon of perturbed D dimensional Reissner-Nordstrom-(A)dS type black holes showing that, similarly to the four dimensional case, mass inflation also occurs for D>4. First, using the homogeneous approximation, we ... More
Using light and heat to controllably switch and reset disorder configuration in nanoscale devicesAug 21 2014Aug 25 2014Quantum dots exhibit reproducible conductance fluctuations at low temperatures due to electron quantum interference. The sensitivity of these fluctuations to the underlying disorder potential has only recently been fully realized. We exploit this sensitivity ... More
Classes on compactifications of the moduli space of curves through solutions to the quantum master equationJul 14 2008Apr 28 2009In this paper we describe a construction which produces classes in a compactification of the moduli space of curves. This construction extends a construction of Kontsevich which produces classes in the open moduli space from the initial data of a cyclic ... More
On the classification of Moore algebras and their deformationsApr 22 2003In this paper we will study deformations of A-infinity algebras. We will also answer questions relating to Moore algebras which are one of the simplest nontrivial examples of an A-infinity algebra. We will compute the Hochschild cohomology of odd Moore ... More
Verifying Temporal Properties of Reactive Systems by TransformationDec 12 2015We show how program transformation techniques can be used for the verification of both safety and liveness properties of reactive systems. In particular, we show how the program transformation technique distillation can be used to transform reactive systems ... More
An obstruction based approach to the Kochen-Specker theoremDec 03 1999In [1] it was shown that the Kochen Specker theorem can be written in terms of the non-existence of global elements of a certain varying set over the partially ordered set of boolean subalgebras of projection operators on some Hilbert space. In this paper, ... More
When is Group Cohomology Finitary?Mar 17 2008If $G$ is a group, then we say that the functor $H^n(G,-)$ is finitary if it commutes with all filtered colimit systems of coefficient modules. We investigate groups with cohomology almost everywhere finitary; that is, groups with $n$th cohomology functors ... More
Noncommutative geometry and compactifications of the moduli space of curvesOct 25 2007In this paper we show that the homology of a certain natural compactification of the moduli space, introduced by Kontsevich in his study of Witten's conjectures, can be described completely algebraically as the homology of a certain differential graded ... More
Finitary Group Cohomology and Group Actions on SpheresMar 17 2008We show that if G is an infinitely generated locally (polycyclic-by-finite) group with cohomology almost everywhere finitary, then every finite subgroup of G acts freely and orthogonally on some sphere.
On two constructions of an effective field theoryFeb 20 2015In this paper we discuss two constructions of an effective field theory starting from a local interaction functional. One relies on the well-established graphical combinatorics of the BPHZ algorithm to renormalize divergent Feynman amplitudes. The other, ... More
A nondiagrammatic description of the Connes-Kreimer Hopf algebraMar 13 2012We demonstrate that the fundamental algebraic structure underlying the Connes-Kreimer Hopf algebra -- the insertion pre-Lie structure on graphs -- corresponds directly to the canonical pre-Lie structure of polynomial vector fields. Using this fact, we ... More
Ground-plane screening of Coulomb interactions in two-dimensional systems: How effectively can one two-dimensional system screen interactions in another?Apr 24 2009Aug 19 2009The use of a nearby metallic ground-plane to limit the range of the Coulomb interactions between carriers is a useful approach in studying the physics of two-dimensional (2D) systems. This approach has been used to study Wigner crystallization of electrons ... More
Long-Term Stability of Horseshoe OrbitsJun 08 2012Aug 24 2012Unlike Trojans, horseshoe coorbitals are not generally considered to be long-term stable (Dermott and Murray, 1981; Murray and Dermott, 1999). As the lifetime of Earth's and Venus's horseshoe coorbitals is expected to be about a Gyr, we investigated the ... More
Growth of Intermediate-Mass Black Holes in Globular ClustersFeb 23 2004We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 solar masses and compare ... More
Diffraction at the TevatronOct 09 2007This article contains a summary of the recent results in diffractive physics at the Tevatron. Results from the CDF diffraction program include the single diffractive to non-diffractive ratio in dijet events, observation of exclusive $e^+e^-$ production ... More
Prospects of Forward Energy Flow and Low-x Physics at the LHCOct 09 2007The LHC will soon provide proton-proton collisions at the unprecedented center of mass energy, $\sqrt{s}=$14 TeV. This not only allows us to probe new regions of high-$p_T$ physics, but also low-$x$ and forward physics. A selection of potential measurements ... More
On the extension of a TCFT to the boundary of the moduli spaceFeb 13 2010The purpose of this paper is to describe an analogue of a construction of Costello in the context of finite-dimensional differential graded Frobenius algebras which produces closed forms on the decorated moduli space of Riemann surfaces. We show that ... More
A super-analogue of Kontsevich's theorem on graph homologyOct 18 2005In this paper we will prove a super-analogue of a well-known result by Kontsevich which states that the homology of a certain complex which is generated by isomorphism classes of oriented graphs can be calculated as the Lie algebra homology of an infinite-dimensional ... More
Quasi-particle Lifetimes in a d_{x^2-y^2} SuperconductorJun 08 2001We consider the lifetime of quasi-particles in a d-wave superconductor due to scattering from antiferromagnetic spin-fluctuations, and explicitly separate the contribution from Umklapp processes which determines the electrical conductivity. Results for ... More
Fast Simulation of Facilitated Spin ModelsOct 13 2005Dec 21 2005We show how to apply the absorbing Markov chain Monte Carlo algorithm of Novotny to simulate kinetically constrained models of glasses. We consider in detail one-spin facilitated models, such as the East model and its generalizations to arbitrary dimensions. ... More
Detection of a Far IR Excess with DIRBE at 60 and 100 MicronsApr 12 2000From analysis of the DIRBE weekly averaged sky maps, we have detected substantial flux in the 60 and 100 micron channels in excess of expected zodiacal and Galactic emission. Two methods are used to separate zodiacal light from more distant emission. ... More
Nuclear scattering of dark matter coupled to a new light scalarOct 06 2008Oct 17 2008We consider the nuclear scattering cross section for the eXciting Dark Matter (XDM) model. In XDM, the Weakly Interacting Massive Particles (WIMPs) couple to the Standard Model only via an intermediate light scalar which mixes with the Higgs: this leads ... More
Photometric Biases in Modern SurveysFeb 06 2019Most surveys use maximum-likelihood (ML) methods to fit models when extracting photometry from images. We show these ML estimators systematically overestimate the flux as a function of the signal-to-noise ratio (SNR) and the number of model parameters ... More
Condition number estimates for matrices arising in NURBS based isogeometric discretizations of elliptic partial differential equationsJun 26 2014We derive bounds for the minimum and maximum eigenvalues and the spectral condition number of matrices for isogeometric discretizations of elliptic partial differential equations in an open, bounded, simply connected Lipschitz domain $\Omega\subset \mathbb{R}^d$, ... More
The Effect of Biased Communications On Both Trusting and Suspicious VotersJun 11 2013In recent studies of political decision-making, apparently anomalous behavior has been observed on the part of voters, in which negative information about a candidate strengthens, rather than weakens, a prior positive opinion about the candidate. This ... More