Results for "J. Thompson"

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Generalized beta-transformations and the entropy of unimodal mapsFeb 10 2016Jan 11 2017Generalized beta-transformations are the class of piecewise continuous interval maps given by taking the beta-transformation $x \mapsto \beta x ~\pmod 1$, where $\beta>1$, and replacing some of the branches with branches of constant negative slope. If ... More
Measures of maximal entropy for suspension flows over the full shiftAug 01 2017Jul 06 2018We consider suspension flows with continuous roof function over the full shift $\Sigma$ on a finite alphabet. For any positive entropy subshift of finite type $Y \subset \Sigma$, we show there exists a roof function such that the measure(s) of maximal ... More
Coding Sequence Density Estimation Via Topological PressureSep 27 2011Jan 08 2014We give a new approach to coding sequence (CDS) density estimation in genomic analysis based on the topological pressure, which we develop from a well known concept in ergodic theory. Topological pressure measures the "weighted information content" of ... More
Unique equilibrium states for flows and homeomorphisms with non-uniform structureMay 14 2015May 25 2016Using an approach due to Bowen, Franco showed that continuous expansive flows with specification have unique equilibrium states for potentials with the Bowen property. We show that this conclusion remains true using weaker non-uniform versions of specification, ... More
Intrinsic ergodicity beyond specification: beta-shifts, S-gap shifts, and their factorsNov 11 2010Jun 17 2011We give sufficient conditions for a shift space $(\Sigma,\sigma)$ to be intrinsically ergodic, along with sufficient conditions for every subshift factor of $\Sigma$ to be intrinsically ergodic. As an application, we show that every subshift factor of ... More
Large deviations for systems with non-uniform structureApr 19 2013Jul 23 2015We use a weak Gibbs property and a weak form of specification to derive level-2 large deviations principles for symbolic systems equipped with a large class of reference measures. This has applications to a broad class of symbolic systems, including $\beta$-shifts, ... More
Unique equilibrium states for Bonatti-Viana diffeomorphismsMay 23 2015Feb 21 2018We show that the robustly transitive diffeomorphisms constructed by Bonatti and Viana have unique equilibrium states for natural classes of potentials. In particular, we characterize the SRB measure as the unique equilibrium state for a suitable geometric ... More
Hadrons of Arbitrary Spin and Heavy Quark SymmetryNov 18 1993Dec 08 1993We present a general construction of the spin content of the Bethe-Salpeter amplitudes (covariant wave functions) for heavy hadrons with arbitrary orbital excitations, using representations of the Lorentz group. These wave functions incorporate the symmetries ... More
Clusters AgeS Experiment. Hot subdwarfs and luminous white dwarf candidates in the field of the globular cluster M4Aug 28 2000May 28 2002We present UBV color magnitude diagrams (CMDs) for the globular cluster M4. The CMDs show a sequence of four luminous blue stars (V<20, U-V<-0.6) which appear to be cluster hot subdwarfs. We present spectra for the three brightest ones. We also note the ... More
SOLA inversions for the core structure of solar-type starsOct 19 2001The Subtractive Optimally Localized Averages (SOLA) method, developed and extensively used in helioseismology, is applied to artificial data to obtain measures of the sound speed inside a solar-type star. In contrast to inversion methods which fit models ... More
Dynamics of the Nearly Parametric PendulumMar 11 2008Nov 26 2010Dynamically stable periodic rotations of a driven pendulum provide a unique mechanism for generating a uniform rotation from bounded excitations. This paper studies the effects of a small ellipticity of the driving, perturbing the classical parametric ... More
Multiwavelength Opportunities and Challenges in the Era of Public Fermi DataDec 29 2009The gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers both opportunities and challenges for multiwavelength and multi-messenger studies. Gamma-ray bursts, pulsars, binary sources, flaring Active Galactic Nuclei, and Galactic transient ... More
Quantum Anisotropic Sigma and Lambda Models as Spin ChainsFeb 16 2018Jun 07 2018We consider lambda and anisotropic deformations of the SU(2) principal chiral model and show how they can be quantized in the Hamiltonian formalism on a lattice as a suitable spin chain. The spin chain is related to the higher spin XXZ Heisenberg chain ... More
Low temperature acoustic properties of amorphous silica and the Tunneling ModelDec 10 1999Internal friction and speed of sound of a-SiO(2) was measured above 6 mK using a torsional oscillator at 90 kHz, controlling for thermal decoupling, non-linear effects, and clamping losses. Strain amplitudes e(A) = 10^{-8} mark the transition between ... More
A photometric survey for variable stars in the globular cluster M5Oct 12 1999We present the results of a photometric survey for variable stars in the nearby globular cluster M5. A 14.8x22.8 arcmin^2 field centered on the cluster was monitored for a total of 37 hours with a CCD camera mounted on the 1.0-m Swope telescope. Five ... More
Eclipsing binaries in the open cluster NGC 2243 - I. PhotometrySep 14 2006We obtained BV time series photometry for 12 variable stars from the field of the old open cluster NGC 2243. The sample includes 3 newly identified detached/semi-detached binaries. There are now four detached eclipsing binaries which are likely members ... More
Bound States of Type I D-StringsJan 19 1998We study the infra-red limit of the O(N) gauge theory that describes the low energy modes of a system of $N$ type I D-strings and provide some support to the conjecture that, in this limit, the theory flows to an orbifold conformal theory. We compute ... More
Thermodynamics of complexity and pattern manipulationSep 30 2015Apr 26 2017Many organisms capitalize on their ability to predict the environment to maximize available free energy, and reinvest this energy to create new complex structures. This functionality relies on the manipulation of patterns - temporally ordered sequences ... More
Probing shells against buckling: a non-destructive technique for laboratory testingDec 13 2017This paper addresses testing of compressed structures, such as shells, that exhibit catastrophic buckling and notorious imperfection sensitivity. The central concept is the probing of a loaded structural specimen by a controlled lateral displacement to ... More
On the effects of rotation on acoustic stellar pulsations: validity domains of perturbative methods and close frequency pairsFeb 02 2011Pulsation frequencies of acoustic modes are calculated for realistic rotating stellar models using both a perturbative and a two-dimensional approach. A comparison between the two yields validity domains which are similar to those previously obtained ... More
Nonlinear Dynamics of Spherical Shells Buckling under Step PressureDec 16 2018Feb 06 2019Dynamic buckling is addressed for complete elastic spherical shells subject to a rapidly applied step in external pressure. Insights from the perspective of nonlinear dynamics reveal essential mathematical features of the buckling phenomena. To capture ... More
Measuring the isotopic composition of trace elements in zircon: application to radiogenic molybdenumJun 23 2018Techniques have been developed to measure the isotopic composition of trace elements from matrices predominantly consisting of interfering isotopes. These techniques have been applied to measuring mass-independent fractionation of molybdenum in ancient ... More
Strong symbolic dynamics for geodesic flow on CAT(-1) spaces and other metric Anosov flowsAug 13 2018We prove that the geodesic flow on a compact, locally CAT(-1) metric space can be coded by a suspension flow over an irreducible shift of finite type with H\"older roof function. This is achieved by showing that the geodesic flow is a metric Anosov flow, ... More
Yang Baxter and Anisotropic Sigma and Lambda Models, Cyclic RG and Exact S-MatricesJun 16 2017Jul 25 2017Integrable deformation of SU(2) sigma and lambda models are considered at the classical and quantum levels. These are the Yang-Baxter and XXZ-type anisotropic deformations. The XXZ type deformations are UV safe in one regime, while in another regime, ... More
Alleviating polarity-conflict at the heterointerfaces of KTaO$_3$/GdScO$_3$ polar complex-oxidesJan 31 2014Sep 09 2014We have synthesized and investigated the heterointerfaces of KTaO$_3$ (KTO) and GdScO$_3$ (GSO), which are both polar complex-oxides along the pseudo-cubic [001] direction. Since their layers have the same, conflicting net charges at interfaces, i.e. ... More
Magnetic Structure of Heavy Fermion Ce2RhIn8Feb 13 2001Mar 02 2001Magnetic structure of the heavy fermion antiferromagnet Ce2RhIn8 is determined using neutron diffraction.
A Radio and Mid-Infrared Survey of Northern Bright-Rimmed CloudsJul 08 2004We have carried out an archival radio, optical and infrared wavelength imaging survey of 44 Bright-Rimmed Clouds (BRCs) using the NRAO/VLA Sky Survey (NVSS) archive, images from the Digitised Sky Survey (DSS) and the Midcourse Space eXperiment (MSX). ... More
A compact high-flux cold atom beam sourceJul 27 2011We report on an efficient and compact high-flux Cs atom beam source based on a retro-reflected two-dimensional magneto-optical trap (2D MOT). We realize an effective pushing field component by tilting the 2D MOT collimators towards a separate three-dimensional ... More
Estimating stellar mean density through seismic inversionsJan 09 2012Determining the mass of stars is crucial both to improving stellar evolution theory and to characterising exoplanetary systems. Asteroseismology offers a promising way to estimate stellar mean density. When combined with accurate radii determinations, ... More
A precursor state to unconventional superconductivity in CeIrIn${_5}$Oct 26 2007We present sensitive measurements of the Hall effect and magnetoresistance in CeIrIn${_5}$ down to temperatures of 50 mK and magnetic fields up to 15 T. The presence of a low temperature coherent Kondo state is established. Deviations from Kohler's rule ... More
Normaloid Weighted Composition Operators on $H^2$Nov 26 2017Jul 26 2018When \ph\ is an analytic self-map of the unit disk with Denjoy-Wolff point $a \in \D$, and $\rho(\W) = \psi(a)$, we give an exact characterization for when \W\ is normaloid. We also determine the spectral radius, essential spectral radius, and essential ... More
Functional inequalities for Feynman-Kac semigroupsNov 08 2018Using stochastic analysis, we prove various gradient estimates and Harnack inequalities for Feynman-Kac semigroups with possibly unbounded potentials. One of the main results is a derivative formula which can be used to characterize a lower bound on Ricci ... More
Chandra and RXTE Spectra of the Burster GS 1826-238Aug 16 2005Using simultaneous observations from Chandra and RXTE, we investigated the LMXB GS 1826-238 with the goal of studying its spectral and timing properties. The uninterrupted Chandra observation captured 6 bursts (RXTE saw 3 of the 6), yielding a recurrence ... More
Physical properties of the noncentrosymmetric superconductor Mg_10Ir_19B_16Jun 14 2007Jan 07 2008Specific heat, electrical resistivity, and magnetic susceptibility measurements on a high quality sample of Mg10Ir19B16 provide a self-consistent determination of its superconducting properties. They indicate that Mg10Ir19B16 is a type-II superconductor ... More
Photoluminescence in amorphous MgSiO_3 silicateJul 02 2013Samples of amorphous MgSiO_3 annealed at temperature steps leading up to their crystallisation temperature show a rise in photoluminescence activity, peaking at ~450C. The photoluminescence band has a main peak at 595nm and a weaker peak at 624nm. We ... More
Two-channel point-contact tunneling theory of superconductorsSep 10 2014We introduce a two-channel tunneling model to generalize the widely used BTK theory of point-contact conductance between a normal metal contact and superconductor. Tunneling of electrons can occur via localized surface states or directly, resulting in ... More
Anomalous Pressure Dependence of Kadowaki-Woods ratio and Crystal Field Effects in Mixed-valence YbInCu4Sep 09 2004Mar 04 2006The mixed-valence (MV) compound YbInCu4 was investigated by electrical resistivity and ac specific heat at low temperatures and high pressures. At atmospheric pressure, its Kadowaki-Woods (KW) ratio, A/\gamma ^2, is 16 times smaller than the universal ... More
A generalization of the Goresky-Klapper conjecture, Part IMay 05 2018For a fixed integer $n\geq 2,$ we show that a permutation of the least residues mod $p$ of the form $f(x)=Ax^k$ mod $p$ cannot map a residue class mod $n$ to just one residue class mod $n$ once $p$ is sufficiently large, other than the maps $f(x)=\pm ... More
Magnetotransport in the CeIrIn${_5}$ system: The influence of antiferromagnetic fluctuationsOct 10 2008We present an overview of magnetotransport measurements on the heavy-fermion superconductor CeIrIn$_5$. Sensitive measurements of the Hall effect and magnetoresistance (MR) are used to elucidate the low temperature phase diagram of this system. The normal-state ... More
Analysis of the normal state magnetotransport in CeIrIn${_5}$Oct 10 2008We present an analysis of the normal state magnetotransport in the heavy fermion superconductor CeIrIn${_5}$. The Hall effect and the transverse magnetoresistance in this material do not appear to be uniquely correlated, as inferred from the field dependence ... More
Optical spectroscopy and ultrafast pump-probe studies on the heavy fermion compound CePt$_2$In$_7$Mar 21 2016We report optical spectroscopy and ultrafast pump-probe measurements on the antiferromagnetic heavy fermion compound CePt$_2$In$_7$, a member showing stronger two dimensionality than other compounds in CeIn$_3$-derived heavy-fermion family. We identify ... More
Carbonate Formation in Non-Aqueous Environments by Solid-Gas Carbonation of SilicatesDec 10 2012We have produced synthetic analogues of cosmic silicates using the Sol Gel method, producing amorphous silicates of composition Mg(x)Ca(1-x)SiO3. Using synchrotron X-ray powder diffraction on Beamline I11 at the Diamond Light Source, together with a newly-commissioned ... More
Detecting Cross-Lingual Plagiarism Using Simulated Word EmbeddingsDec 29 2017Jan 03 2018Cross-lingual plagiarism (CLP) occurs when texts written in one language are translated into a different language and used without acknowledging the original sources. One of the most common methods for detecting CLP requires online machine translators ... More
Khovanov complexes of rational tanglesJan 26 2017Dec 12 2018We show that the Khovanov complex of a rational tangle has a very simple representative whose backbone of non-zero morphisms forms a zig-zag. Furthermore, this minimal complex can be computed quickly by an inductive algorithm. (For example, we calculate ... More
Finding geodesics in a triangulated 2-sphereAug 25 2014Sep 09 2014Let S be a triangulated 2-sphere with fixed triangulation T. We apply the methods of thin position from knot theory to obtain a simple version of the three geodesics theorem for the 2-sphere [5]. In general these three geodesics may be unstable, corresponding, ... More
Some Graftings of Complex Projective Structures with Schottky HolonomyDec 10 2010Jan 27 2013Let $\mathcal{G}^*(S,\rho)$ be the graph whose vertices are marked complex projective structures with holonomy $\rho$ and whose edges are graftings from one vertex to another. If $\rho$ is quasi-Fuchsian, a theorem of Goldman implies that $\mathcal{G}^*(S,\rho)$ ... More
The spectrum of large unitarily invariant models with increasingly many spikesMar 29 2019Apr 02 2019In this paper we study random matrix models where the matrices in question contain infinitely many spikes. Recent work has characterized the possible outliers in the spectrum of large deformed unitarily invariant models when the number of spikes in the ... More
The Sum of Four Squares Over Real Quadratic Number FieldsOct 21 2016May 23 2018Well-known results of Lagrange and Jacobi prove that the every $m \in \mathbb N$ can be expressed as a sum of four integer squares, and the number $r(m)$ of such representations can be given by an explicit formula in $m$. In this paper, we prove that ... More
Degenerations of K3 Surfaces of Degree TwoOct 28 2010Dec 19 2011We consider a semistable degeneration of K3 surfaces, equipped with an effective divisor that defines a polarisation of degree two on a general fibre. We show that the map to the relative log canonical model of the degeneration maps every fibre to either ... More
Explicit Models for Threefolds Fibred by K3 Surfaces of Degree TwoJan 25 2011Aug 17 2012We consider threefolds that admit a fibration by K3 surfaces over a nonsingular curve, equipped with a divisorial sheaf that defines a polarisation of degree two on the general fibre. Under certain assumptions on the threefold we show that its relative ... More
Tori and Heegaard splittingsMar 27 2016Haken showed that the Heegaard splittings of reducible 3-manifolds are reducible, that is, a reducing 2-sphere can be found which intersects the Heegaard surface in a single simple closed curve. When the genus of the "interesting" surface increases from ... More
Dehn surgery on complicated fibered knots in the 3-sphereApr 17 2016Let K be a fibered knot in the 3-sphere. We show that if the monodromy of K is sufficiently complicated, then Dehn surgery on K cannot yield a lens space. Work of Yi Ni shows that if K has a lens space surgery then it is fibered. Combining this with our ... More
A generalisation of Dickson's commutative division algebrasFeb 28 2019Dickson's commutative semifields are an important class of finite division algebras. We generalise Dickson's construction of commutative division algebras by doubling both finite field extensions and central simple algebras and not restricting us to the ... More
An Unstable Change of Rings for Morava E-TheorySep 12 2014Mar 16 2018The Bousfield-Kan (or unstable Adams) spectral sequence can be constructed for various homology theories such as Brown-Peterson homology theory BP, Johnson-Wilson theory $E(n)$, or Morava $E$-theory $E_n$. For nice spaces the $E_2$-term is given by Ext ... More
The rate of escape of random walks on polycyclic and metabelian groupsOct 05 2010Sep 13 2011We use subgroup distortion to determine the rate of escape of a simple random walk on a class of polycyclic groups, and we show that the rate of escape is invariant under changes of generating set for these groups. For metabelian groups, we define a stronger ... More
The Gamma-ray Sky with FermiAug 08 2013Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, solar flares, and flaring ... More
Gamma Ray Pulsars: ObservationsJan 03 2001High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting ... More
Advances in Shell Buckling: Theory and ExperimentsSep 10 2014In a recent feature article in this journal, co-authored by Gert van der Heijden, I described the static-dynamic analogy and its role in understanding the localized post-buckling of shell-like structures, looking exclusively at integrable systems. We ... More
Measurements of alpha_s from hadronic event shapes in e+e- annihilationDec 02 1998New studies of hadronic event shape observables in e+ e- collisions between 13 and 183 GeV CM energy have enabled the running of alpha_s to be confirmed and the validity of non-perturbative power-law corrections to be investigated. A more precise value ... More
Grand Challenges in the Physics of the Sun and Sun-like StarsJun 17 2014The study of stellar structure and evolution is one of the main building blocks of astrophysics, and the Sun has an importance both as the star that is most amenable to detailed study and as the star that has by far the biggest impact on the Earth and ... More
Towards a Molecular Inventory of Protostellar DiscsNov 27 2003The chemical environment in circumstellar discs is a unique diagnostic of the thermal, physical and chemical environment. In this paper we examine the structure of star formation regions giving rise to low mass stars, and the chemical environment inside ... More
Monitoring the Gamma-ray Sky through 4.5 Years of Fermi LAT Flare Advocate ServiceMar 17 2013The Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides for a quick look and review of the gamma-ray sky observed daily by the Fermi Large Area Telescope (LAT). The FA-GSW service provides alerts and communicates to the ... More
Profiling filaments: comparing near-infrared extinction and submillimetre data in TMC-1Jun 21 2012Interstellar filaments are an important part of star formation. To understand the structure of filaments, cross-section profiles are often fitted with Plummer profiles. This profiling is often done with submm studies, such as Herschel. It would be convenient ... More
Superconducting and Normal State Properties of Heavily Hole-Doped DiamondSep 23 2004We report measurements of the specific heat, Hall effect, upper critical field and resistivity on bulk, B-doped diamond prepared by reacting amorphous B and graphite under high-pressure/high-temperature conditions. These experiments establish unambiguous ... More
The Peculiar Pulsations of PY VulApr 29 2004The pulsating white dwarf star PY Vul (G~185-32) exhibits pulsation modes with peculiar properties that set it apart from other variable stars in the ZZ Ceti (DAV) class. These peculiarities include a low total pulsation amplitude, a mode with bizarre ... More
Mode Identification from Combination Frequency Amplitudes in ZZ Ceti StarsNov 15 2005The lightcurves of variable DA stars are usually multi-periodic and non-sinusoidal, so that their Fourier transforms show peaks at eigenfrequencies of the pulsation modes and at sums and differences of these frequencies. These combination frequencies ... More
A criterion for topological entropy to decrease under normalised Ricci flowNov 16 2009Dec 18 2009In 2004, Manning showed that the topological entropy of the geodesic flow for a surface of negative curvature decreases as the metric evolves under the normalised Ricci flow. It is an interesting open problem, also due to Manning, to determine to what ... More
Heavy surface state in a possible topological Kondo insulator: Magneto-thermoelectric transport on the (011)-plane of SmB$_6$Dec 17 2014Feb 25 2015Motivated by the high sensitivity to Fermi surface topology and scattering mechanisms in magneto-thermoelectric transport, we have measured the thermopower and Nernst effect on the (011)-plane of the proposed topological Kondo insulator SmB$_6$. These ... More
The Clusters AgeS Experiment (CASE). Variable stars in the field of the globular cluster NGC 6362Dec 29 2014The field of the globular cluster NGC 6362 was monitored between 1995 and 2009 in a search for variable stars. BV light curves were obtained for 69 periodic variables including 34 known RR Lyr stars, 10 known objects of other types and 25 newly detected ... More
Clusters AgeS Experiment. RR Lyr Variables in the Globular Cluster NGC 6362May 31 2000We present V and B-band CCD photometry of 35 RR Lyr stars in the southern hemisphere globular cluster NGC 6362. Fourier decomposition of the light curves was used to estimate the basic properties of these variables. From the analysis of the RRc stars ... More
Cluster AgeS Experiment (CASE): Deficiency of observed dwarf novae in globular clustersApr 07 2008We present the results of a search for dwarf novae (DNe) in globular clusters (GCs). It is based on the largest available homogeneous sample of observations, in terms of the time span, number of observations and number of clusters. It includes 16 Galactic ... More
The Multiwavelength Approach to Unidentified Gamma-Ray SourcesJul 20 2004As the highest-energy photons, gamma rays have an inherent interest to astrophysicists and particle physicists studying high-energy, nonthermal processes. Gamma-ray telescopes complement those at other wavelengths, especially radio, optical, and X-ray, ... More
Gamma Radiation from PSR B1055-52Nov 13 1998The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics ... More
Boundary Conditions for Interacting MembranesDec 17 2009Jan 29 2010We investigate supersymmetric boundary conditions in both the Bagger-Lambert and the ABJM theories of interacting membranes. We find boundary conditions associated to the fivebrane, the ninebrane and the M-theory wave. For the ABJM theory we are able ... More
Parity-Time Symmetry in Coherently Coupled Vertical Cavity Laser ArraysOct 05 2016Dec 13 2016We report parity-time (PT) symmetry breaking in electrically injected, coherently coupled, vertical cavity surface emitting laser arrays. We predict beam steering, mode evolution and mode hopping as a consequence of the non-Hermiticity of the array analyzed ... More
Lattice Models of Nonequilibrium Bacterial DynamicsDec 03 2010Feb 23 2011We study a model of self propelled particles exhibiting run and tumble dynamics on lattice. This non-Brownian diffusion is characterised by a random walk with a finite persistence length between changes of direction, and is inspired by the motion of bacteria ... More
Irregular sets, the $β$-transformation and the almost specification propertyMay 06 2009May 02 2012Let $(X,d)$ be a compact metric space, $f:X \mapsto X$ be a continuous map satisfying a property we call almost specification (which is slightly weaker than the $g$-almost product property of Pfister and Sullivan), and $\phi$ be a continuous function ... More
Interplay of the spin density wave and a possible Fulde-Ferrell-Larkin-Ovchinnikov state in $\mathrm{CeCoIn_5}$ in rotating magnetic fieldFeb 13 2019The $d$-wave superconductor $\mathrm{CeCoIn_5}$ has been proposed as a strong candidate for supporting the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state near the low-temperature boundary of its upper critical field. Neutron diffraction, however, finds ... More
Space Detectors for Gamma Rays (100 MeV - 100 GeV): from EGRET to Fermi LATJun 25 2015The design of spaceborne high-energy (E>100 MeV) gamma-ray detectors depends on two principal factors: (1) the basic physics of detecting and measuring the properties of the gamma rays; and (2) the constraints of operating such a detector in space for ... More
Gamma-Ray Pulsar Studies with GLASTNov 27 2007Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus ... More
Gamma Ray Pulsars: Multiwavelength ObservationsDec 10 2003High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves ... More
High Resolution Spectroscopy of the Pulsating White Dwarf G29-38Mar 25 2003We present the analysis of time-resolved, high resolution spectra of the cool white dwarf pulsator, G29-38. From measuring the Doppler shifts of the H-alpha core, we detect velocity changes as large as 16.5 km/s and conclude that they are due to the horizontal ... More
A multiscale mathematical model of tumour invasive growthMar 24 2016Known as one of the hallmarks of cancer [30], cancer cell invasion of human body tissue is a complicated spatio-temporal multiscale process which enables a localised solid tumour to transform into a systemic, metastatic and fatal disease. This process ... More
Interferometric Observations of V838 MonocerotisFeb 15 2005Feb 16 2005We have used long-baseline near-IR interferometry to resolve the peculiar eruptive variable V838 Mon and to provide the first direct measurement of its angular size. Assuming a uniform disk model for the emission we derive an apparent angular diameter ... More
Pressure-induced superconductivity in single crystal CaFe2As2Jul 04 2008We report pressure-induced superconductivity in a single crystal of CaFe2As2. At atmospheric pressure, this material is antiferromagnetic below 170 K but under an applied pressure of 0.69 GPa becomes superconducting, with a transition temperature Tc exceeding ... More
Optical and submillimetre observations of Bok globules -- tracing the magnetic field from low to high densityJun 01 2009We present optical and submillimetre polarimetry data of the Bok globule CB3 and optical polarimetry data of the Bok globule CB246. We use each set of polarimetry data to infer the B-field orientation in each of the clouds. The optical data can only be ... More
The Antesonic Condition for the Explosion of Core-Collapse Supernovae I: Spherically Symmetric Polytropic Models: Stability & Wind EmergenceJan 08 2018Jan 08 2019Shock revival in core-collapse supernovae (CCSNe) may be due to the neutrino mechanism. While it is known that in a neutrino-powered CCSN, explosion begins when the neutrino luminosity of the proto-neutron star exceeds a critical value, the physics of ... More
Coherence and Raman sideband cooling of a single atom in an optical tweezerSep 13 2012We investigate quantum control of a single atom in an optical tweezer trap created by a tightly focused optical beam. We show that longitudinal polarization components in the dipole trap arising from the breakdown of the paraxial approximation give rise ... More
Pressure-tuned First-order Phase Transition and Accompanying Resistivity Anomaly in CeZn_{1-δ}Sb_{2}Jun 21 2005Mar 07 2006The Kondo lattice system CeZn_{0.66}Sb_{2} is studied by the electrical resistivity and ac magnetic susceptibility measurements at several pressures. At P=0 kbar, ferromagnetic and antiferromagnetic transitions appear at 3.6 and 0.8 K, respectively. The ... More
Latent protein treesAug 11 2011Dec 05 2013Unbiased, label-free proteomics is becoming a powerful technique for measuring protein expression in almost any biological sample. The output of these measurements after preprocessing is a collection of features and their associated intensities for each ... More
Low-temperature triple-alpha rate in a full three-body modelDec 09 2011Aug 02 2012A new full three-body method is introduced to compute the rate of the triple-alpha capture reaction which is the primary source of $^{12}$C in stars. In this work, we combine the Faddeev hyperspherical harmonics and the R-matrix method to obtain a full ... More
Vortexlike excitations in the heavy-fermion superconductor CeIrIn$_5$Feb 25 2016May 05 2016We report a systematic study of temperature- and field-dependent charge ($\boldsymbol{\rho}$) and entropy ($\mathbf{S}$) transport in the heavy-fermion superconductor CeIrIn$_5$. Its large positive thermopower $S_{xx}$ is typical of Ce-based Kondo lattice ... More
Pressure-enhanced superconductivity in Eu$_3$Bi$_2$S$_4$F$_4$Dec 17 2014The pressure effect on the newly discovered charge-transferred BiS$_2$-based superconductor, Eu$_3$Bi$_2$S$_4$F$_4$, with a $T_c$ of 1.5 K at ambient pressure, is investigated by transport and magnetic measurements. Accompanied with the enhancement of ... More
Pressure-tuned quantum criticality in the antiferromagnetic Kondo semi-metal CeNi$_{2-δ}$As$_2$Jan 14 2015Oct 22 2015The easily tuned balance among competing interactions in Kondo-lattice metals allows access to a zero-temperature, continuous transition between magnetically ordered and disordered phases, a quantum-critical point (QCP). Indeed, these highly correlated ... More
Non-aqueous formation of the calcium carbonate polymorph vaterite: astrophysical implicationsMar 15 2013We study the formation of calcium carbonate, through the solid-gas interaction of amorphous Ca-silicate with gaseous CO2, at elevated pressures, and link this to the possible presence of calcium carbonate in a number of circumstellar and planetary environments. ... More
Pressure-Tuned Point-Contact Spectroscopy of URu2Si2 from Hidden Order to Antiferromagnetic States: Similarity of the Fermi Surface GappingDec 23 2011We report soft point-contact spectroscopy studies of URu2Si2 both in the hidder order (HO) and the large-moment antiferromagnetic (LMAF) states accessed by pressure. In the HO state at ambient pressure, the spectroscopy shows two asymmetric peaks around ... More
Helioseismology over the solar cycleMar 19 2010Helioseismology has produced unprecedented measurements of the Sun's internal structure and dynamics over the past 25 years. Much of this work has been based on global helioseismology. Now local helioseismology too is showing its great promise. This review ... More
Gamma ray astrophysics: the EGRET resultsNov 05 2008Cosmic gamma rays provide insight into some of the most dynamic processes in the Universe. At the dawn of a new generation of gamma-ray telescopes, this review summarizes results from the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton ... More
A Color Analysis of the NICMOS Parallel Image ArchiveMay 24 2000We present a photometric analysis of all high Galactic lattitude (|b| > 20d) broad-band parallel images taken by the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument during its initial lifetime in HST Cycle 7. These images, taken ... More
Reverse engineering pairwise entanglementFeb 20 2019Designing algorithms for medium and large scale quantum computers is not easy. In previous work we have suggested, and developed, the idea of using machine learning techniques to train a quantum system such that the desired process is "learned," thus ... More