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Results for "C. M. Lewis"

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Design of Experiments for ScreeningOct 18 2015The aim of this paper is to review methods of designing screening experiments, ranging from designs originally developed for physical experiments to those especially tailored to experiments on numerical models. The strengths and weaknesses of the various ... More
Ab Initio Lifetime and Concomitant Double-Excitation Character of Plasmons at Metallic DensitiesOct 15 2018We use state-of-the-art equation-of-motion coupled-cluster theory with single and double excitations (EOM-CCSD) to calculate the dynamic structure factor of the uniform electron gas. Our calculations are performed at densities corresponding to Wigner-Seitz ... More
Vertex corrections to the polarizability do not improve the GW approximation for moleculesSep 30 2018The $GW$ approximation is based on the neglect of vertex corrections, which appear in the exact self-energy and the exact polarizability. Here, we investigate the importance of vertex corrections in the polarizability only. We calculate the polarizability ... More
Model selection via Bayesian information capacity designs for generalised linear modelsJan 29 2016Oct 26 2016The first investigation is made of designs for screening experiments where the response variable is approximated by a generalised linear model. A Bayesian information capacity criterion is defined for the selection of designs that are robust to the form ... More
Model selection via Bayesian information capacity designs for generalised linear modelsJan 29 2016Aug 14 2016We provide the first investigation of designs for screening experiments where the response variable is approximated by a generalised linear model. We define the Bayesian information capacity criterion for the selection of designs that are robust to the ... More
Gas condensation within a bundle of carbon nanotubes - effects of screeningOct 01 2000We study the low temperature phase behavior of hydrogen within a bundle of carbon nanotubes. Because the carbon environment weakens the attraction between molecules within the same interstitial channel (IC), the ground state of the one-dimensional (1D) ... More
Deep inelastic events containing two forward jets at HERAJul 17 1997We use the BFKL equation to calculate the rate of deep inelastic scattering events containing two forward jets (adjacent to the proton remnants) at HERA. We compare the production of two forward jets with that of only one forward jet (the "Mueller" process). ... More
Response of CsI[Na] to Nuclear Recoils: Impact on Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS)Jul 10 2019A new measurement of the quenching factor for low-energy nuclear recoils in CsI[Na] is presented. Past measurements are revisited, identifying and correcting several systematic effects. The resulting global data are well-described by a physics-based model ... More
Response of CsI[Na] to Nuclear Recoils: Impact on Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS)Jul 10 2019Jul 13 2019A new measurement of the quenching factor for low-energy nuclear recoils in CsI[Na] is presented. Past measurements are revisited, identifying and correcting several systematic effects. The resulting global data are well-described by a physics-based model ... More
Microlensing Induced Spectral Variability In Q2237+0305Aug 12 1995Several macrolensed systems exhibit photometric variability consistent with microlensing due to objects of stellar mass located in the lens. The degree of microlensing amplification is dependent upon the size of the source, with smaller sources being ... More
Observable jets from the BFKL chainJun 19 1996We derive a modified form of the BFKL equation which enables the structure of the gluon emissions to be studied in small $x$ deep inelastic scattering. The equation incorporates the resummation of the virtual and unresolved real gluon emissions. We solve ... More
Astrometric and Photometric Measurements of Binary Stars with Adaptive Optics: Observations from 2002Dec 15 2010The adaptive optics system at the 3.6 m AEOS telescope was used to measure the astrometry and differential magnitude in I-band of 56 binary stars in 2002. The astrometric measurements will be of use for future orbital determination, and the photometric ... More
Π^0_1 classes, strong minimal covers and hyperimmune-free degreesNov 02 2007We investigate issues surrounding an old question of Yates' as to the existence of a minimal Turing degree with no strong minimal cover, specifically with respect to the hyperimmune-free degrees.
On spherically-symmetric accretion by a collisionless polytropeApr 02 2001An isolated, spherically-symmetric, self-gravitating, collisionless system is always a polytrope when it reaches equilibrium (Nakamura 2000). This strongly suggests as a corollary, however, that the same polytrope dominates its precursor states, since ... More
Hierarchical Evidence Accumulation in the Pseiki System and Experiments in Model-Driven Mobile Robot NavigationMar 27 2013In this paper, we will review the process of evidence accumulation in the PSEIKI system for expectation-driven interpretation of images of 3-D scenes. Expectations are presented to PSEIKI as a geometrical hierarchy of abstractions. PSEIKI's job is then ... More
Does the momentum flux generated by gravitational contraction drive AGB mass-loss?Jul 21 1997Jul 23 1997Gravitational contraction always generates a radially directed momentum flux. A particularly simple example occurs in the electron-degenerate cores of AGB stars, which contract steadily under the addition of helium ashes from shell hydrogen burning. The ... More
A renewed search for water maser emission from Mira variablesJun 19 1997Jun 20 1997There is an approximately 60% detection rate for 1612 MHz masers in association with red, color-selected IRAS sources, though few are detected from the bluer circumstellar shells of Mira variables. On the other hand and complementarily, past, pre-IRAS ... More
Closing the Wedge with 300 fb^-1 and 3000 fb^-1 at the LHC: A Snowmass White PaperAug 08 2013The discovery of a Higgs boson at the LHC begins the era of directly measuring the mechanism of electroweak symmetry breaking (EWSB). Searching for extensions of the Standard Model (SM) EWSB sector at the LHC is of vital importance. An important extension ... More
The Detectability of Moons of Extra-Solar PlanetsSep 25 2011The detectability of moons of extra-solar planets is investigated, focussing on the time-of-arrival perturbation technique, a method for detecting moons of pulsar planets, and the photometric transit timing technique, a method for detecting moons of transiting ... More
The Development of a Hybrid Asymptotic Expansion for the Hardy Fuction Z(t), Consisting of Just [2*sqrt(2)-2]*sqrt(t/(2*pi)) Main Sum Terms, some 17% less than the celebrated Riemann-Siegel FormulaFeb 17 2015This paper begins with a re-examination of the Riemann-Siegel Integral, which first discovered amongst by Bessel-Hagen in 1926 and expanded upon by C. L. Siegel on his 1932 account of Riemanns unpublished work on the zeta function. By application of standard ... More
On the Hamiltonian Number of a Planar GraphAug 27 2015The Hamiltonian number of a connected graph is the minimum of the lengths of the closed, spanning walks in the graph. In 1968, Grinberg published a necessary condition for the existence of a Hamiltonian cycle in a planar graph, formulated in terms of ... More
Hindered rotation of H2 adsorbed interstitially in nanotube bundlesOct 12 2001A theoretical study on the rotational dynamics of H2 molecules trapped in the interstitial channels (ICs) of a carbon nanotube bundle is presented. The potential used in this study is modeled as a sum of atom-atom (C-H) van der Waals interactions and ... More
Microlensing induced spectral variability in Q2237+0305Nov 03 1997We present both photometry and spectra of the individual images of the quadruple gravitational lens system Q2237+0305. Comparison of spectra obtained at two epochs, separated by $\sim~3\,$years, shows evidence for significant changes in the emission line ... More
Advanced Diagnostics for the Study of Linearly Polarized Emission. I: DerivationOct 20 2017Linearly polarized emission is described, in general, in terms of the Stokes parameters $Q$ and $U$, from which the polarization intensity and polarization angle can be determined. Although the polarization intensity and polarization angle provide an ... More
Precision physics with a wide band super neutrino beamJul 17 2006Sep 20 2006We carry out a state-of-the-art assessment of long baseline neutrino oscillation experiments with wide band beams. We describe the feasibility of an experimental program using existing high energy accelerator facilities, a new intense wide band neutrino ... More
A critical assessment of models of pair-interactions and screening used in analyzing recent warm-dense matter (WDM) experimentsApr 10 2016Ultra-fast laser experiments yield increasingly reliable data on warm-dense matter (WDM), but rely on entrenched simplistic theoretical models. We re-analyze two topical experiments, avoiding (i) {\it ad hoc} core-repulsion models, (ii) "Yukawa screening" ... More
An analysis of photoemission and inverse photoemission spectra of Si(111) and sulphur-passivated InP(001) surfacesMay 01 1997Photoemission (PES) and inverse-photoemission spectra (IPES) for the sulphur-passivated InP(001) surface are compared with theoretical predictions based on density-functional calculations. As a test case for our methods, we also present a corresponding ... More
A Keck/DEIMOS spectroscopic survey of faint Galactic satellites: searching for the least massive dwarf galaxiesMay 31 2007[abridged] We present the results of a spectroscopic survey of the recently discovered faint Milky Way satellites Boo, UMaI, UMaII and Wil1. Using the DEIMOS spectrograph on Keck, we have obtained samples that contain from 15 to 85 probable members of ... More
Star Formation at Redshift One: Preliminary results from an H-alpha SurveyJul 12 2004We present the first successful demonstration of multi-object near-infrared spectroscopy on high redshift galaxies. Our objective is to address the true star formation history of the universe at z~1, a crucial epoch which some have suggested is the peak ... More
Critical X-ray Scattering Studies of Jahn-Teller Phase Transitions in TbV$_{1-x}$As$_{x}$O$_{4}$Jan 14 2008The critical behaviour associated with cooperative Jahn-Teller phase transitions in TbV$_{1-x}$As$_{x}$O$_{4}$ (where \textit{x} = 0, 0.17, 1) single crystals have been studied using high resolution x-ray scattering. These materials undergo continuous ... More
The Function of Communities in Protein Interaction Networks at Multiple ScalesApr 06 2009Mar 12 2010Background: If biology is modular then clusters, or communities, of proteins derived using only protein interaction network structure should define protein modules with similar biological roles. We investigate the link between biological modules and network ... More
Isochoric, isobaric and ultrafast conductivities of aluminum, lithium and carbon in the warm dense matter (WDM) regimeSep 21 2017We study the conductivities $\sigma$ of (i) the equilibrium isochoric state ($\sigma_{\rm is}$), (ii) the equilibrium isobaric state ($\sigma_{\rm ib}$), and also the (iii) non-equilibrium ultrafast matter (UFM) state ($\sigma_{\rm uf}$) with the ion ... More
Reciprocity Theorems for Ab Initio Force CalculationsAug 22 1996We present a method for calculating ab initio interatomic forces which scales quadratically with the size of the system and provides a physically transparent representation of the force in terms of the spatial variation of the electronic charge density. ... More
The Cosmic Microwave Background and Inflation ParametersJun 07 2004We review the currrent cosmic parameter determinations of relevance to inflation using the WMAP-1year, Boomerang, CBI, Acbar and other CMB data. The basic steps in the pipelines which determine the bandpowers from the raw data from which these estimations ... More
Efficiency in nanostructured thermionic and thermoelectric devicesJun 16 2005Advances in solid-state device design now allow the spectrum of transmitted electrons in thermionic and thermoelectric devices to be engineered in ways that were not previously possible. Here we show that the shape of the electron energy spectrum in these ... More
Reflected Light Phase Curves in the TESS EraMay 29 2019The reflected light signal from a planet throughout its orbit is a powerful probe of a planet's atmospheric properties. There are a number of planets that are amenable to reflected light phase curve studies with present and future space-based instrumentation ... More
Dual Band Electrodes in Generator-Collector Mode: Simultaneous Measurement of Two SpeciesJun 19 2013A computational model for the simulation of a double band collector-generator experiment is applied to the situation where two electrochemical reactions occur concurrently. It is shown that chronoamperometric measurements can be used to take advantage ... More
Correcting the influence of an asymmetric line spread function in 2-degree Field spectrograph dataMar 31 2005May 24 2005We investigate the role of asymmetries in the line spread function of the 2-degree field spectrograph and the variations in these asymmetries with the CCD, the plate, the time of observation and the fibre. A data-reduction pipeline is developed that takes ... More
Reply to comment by Witte et al. on "Isochoric, isobaric, and ultrafast conductivities of aluminum, lithium,and carbon in the warm dense matter regime", Phys. Rev. E $96$, 053206 (2017)May 08 2019In Phys. Rev. E, $99$, 047201 (2019) Witte {\it et al.} have commented on our conductivity calculations [Phys. Rev. E $96$, 053206 (2017)] for warm dense matter (WDM). (i) They criticize our use of the spherically-averaged structure factor $S(k)$ for ... More
Structure and Vibrations of the Vicinal Copper (211) SurfaceDec 05 1997We report a first principles theoretical study of the surface relaxation and lattice dynamics of the Cu(211) surface using the plane wave pseudopotential method. We find large atomic relaxations for the first several atomic layers near the step edges ... More
Right-Handed Neutrinos as the Origin of the Electroweak ScaleApr 24 2014Aug 21 2014The insular nature of the Standard Model may be explained if the Higgs mass parameter is only sensitive to quantum corrections from physical states. Starting from a scale-free electroweak sector at tree-level, we postulate that quantum effects of heavy ... More
Minimal dimensional representations of reduced enveloping algebras for $\mathfrak{gl}_n$May 03 2018Let $\mathfrak g = \mathfrak{gl}_N(k)$, where $k$ is an algebraically closed field of characteristic $p > 0$, and $N \in \mathbb Z_{\ge 1}$. Let $\chi \in \mathfrak g^*$ and denote by $U_\chi(\mathfrak g)$ the corresponding reduced enveloping algebra. ... More
More about excited bottomonium radiative decaysJul 16 2012Sep 18 2012Radiative decays of bottomonium are revisited, focusing on contributions from higher-order relativistic effects. The leading relativistic correction to the magnetic spin-flip operator at the photon vertex is found to be particularly important. The combination ... More
S and P-wave heavy-light mesons in lattice NRQCDMar 15 2000Oct 02 2000The mass spectrum of S and P-wave mesons containing a single heavy quark is computed in the quenched approximation, using NRQCD up to third order in the inverse heavy quark mass expansion. Previous results found third order contributions which are as ... More
O(1/M^3) effects for heavy-light mesons in lattice NRQCDMar 03 1998May 30 1998The masses of spin-singlet and spin-triplet S-wave mesons containing a single heavy quark are computed in the quenched approximation. The light quark action and gauge field action are both classically-improved and tadpole-improved, and the couplings to ... More
Light vector meson decay constants and the renormalization factor from a tadpole-improved actionOct 18 1996The rho, K* and phi decay constants and the vector current renormalization factor are studied by using an O(a^2) classically-improved, tadpole-improved action. Tree-level calculations are used to show how the classical improvement of the action, involving ... More
Probes of turbulent driving mechanisms in molecular clouds from fluctuations in synchrotron intensityDec 16 2016Previous studies have shown that star formation depends on the driving of molecular cloud turbulence, and differences in the driving can produce an order of magnitude difference in the star formation rate. The turbulent driving is characterised by the ... More
Singlet Model Interference Effects with High Scale UV PhysicsMay 16 2016Oct 17 2016One of the simplest extensions of the Standard Model (SM) is the addition of a scalar gauge singlet, S. If S is not forbidden by a symmetry from mixing with the Standard Model Higgs boson, the mixing will generate non-SM rates for Higgs production and ... More
The charmed and bottom meson spectrum from lattice NRQCDOct 02 2000The mass spectrum of S and P-wave mesons containing a single heavy quark has been computed using quenched lattice nonrelativistic QCD. Numerical results have been obtained at first, second and third order in the heavy quark expansion, so convergence can ... More
The rho meson decay constant using a tadpole-improved actionJul 25 1996The rho meson decay constant and the associated renormalization factor are computed in the quenched approximation on coarse lattices using a tadpole-improved action which is corrected at the classical level to O(a^2). The improvement is displayed by comparing ... More
Next Generation of Telescopes or Dynamics Required to Determine if Exo-Moons have Prograde or Retrograde OrbitsJul 16 2014We survey the methods proposed in the literature for detecting moons of extrasolar planets in terms of their ability to distinguish between prograde and retrograde moon orbits, an important tracer of moon formation channel. We find that most moon detection ... More
Restricted shifted Yangians and restricted finite $W$-algebrasMar 07 2019We study the truncated shifted Yangian $Y_{n,l}(\sigma)$ over an algebraically closed field $\mathbb{k}$ of characteristic $p > 0$, which is known to be isomorphic to the finite $W$-algebra $U(\mathfrak{g}, e)$ associated to a corresponding nilpotent ... More
Dark Matter from Hidden ForcesSep 25 2013Oct 11 2013We examine the possibility that dark matter may be the manifestation of dark forces of a hidden sector, i.e. "Dark Force = Dark Matter." As an illustrative and minimal example we consider the hidden SU(2)_h x U(1)_h gauge group. The hidden dynamics is ... More
Excited Upsilon Radiative DecaysAug 04 2011Nov 13 2011Bottomonium S-wave states were studied using lattice NRQCD. Masses of ground and excited states were calculated using multiexponential fitting to a set of correlation functions constructed using both local and wavefunction-smeared operators. Three-point ... More
S-wave charmed mesons in lattice NRQCDSep 04 1998Heavy-light mesons can be studied using the 1/M expansion of NRQCD, provided the heavy quark mass is sufficiently large. Calculations of the S-wave charmed meson masses from a classically and tadpole-improved action are presented. A comparison of O(1/M), ... More
Minimal dimensional representations of reduced enveloping algebras for $\mathfrak{gl}_n$May 03 2018Apr 12 2019Let $\mathfrak g = \mathfrak{gl}_N(k)$, where $k$ is an algebraically closed field of characteristic $p > 0$, and $N \in \mathbb Z_{\ge 1}$. Let $\chi \in \mathfrak g^*$ and denote by $U_\chi(\mathfrak g)$ the corresponding reduced enveloping algebra. ... More
NLO Corrections to Double Higgs Production in the Higgs Singlet ModelAug 21 2015Nov 12 2015Higgs pair production at the LHC from gluon fusion is small in the Standard Model, but can be enhanced in models where a resonant enhancement is allowed. We examine the effect of a resonant contribution from a second scalar arising in a model with a gauge ... More
Large Scale Cosmic Microwave Background Anisotropies and Dark EnergyJul 05 2003Aug 29 2003In this note we investigate the effects of perturbations in a dark energy component with a constant equation of state on large scale cosmic microwave background anisotropies. The inclusion of perturbations increases the large scale power. We investigate ... More
Cyclic variations with twice the accretion disk precession period in the old nova V603 AquilaeFeb 22 2018A dense series of long and high time resolution light curves of the old nova V603 Aql, covering 22 nights (19 of which are consecutive), are analyzed in order to identify and characterize variations on the time scale of hours and days. The well known ... More
Higher angular momentum states of bottomonium in lattice NRQCDApr 20 2012Jun 25 2012On a cubic lattice the zero-momentum meson states have one of 20 possible Lambda^{PC} combinations where Lambda labels the irreducible representation of the octahedral group. Each continuum bottomonium state with specific J^{PC} quantum numbers is contained ... More
Bottom baryons from a dynamical lattice QCD simulationJun 29 2008Jan 12 2009Bottom baryon masses are calculated based on a 2+1 flavor dynamical lattice QCD simulation. The gauge field configurations were computed by the CP-PACS and JLQCD collaborations using an improved clover action. The bottom quark is described using lattice ... More
Spontaneous symmetry breaking in a two-doublet lattice Higgs modelMay 29 2010Sep 01 2010An SU(2) lattice gauge theory with two doublets of complex scalar fields is considered. All continuous symmetries are identified and, using the nonperturbative methods of lattice field theory, the phase diagram is mapped out by direct numerical simulation. ... More
Heavy-light meson spectrum with and without NRQCDOct 02 2000Results for the spectrum of S and P-wave charmed mesons are obtained in the quenched approximation from a tadpole-improved anisotropic gauge field action and a D234 quark action. This is compared to the spectrum obtained from an NRQCD charm quark and ... More
P-wave heavy-light mesons using NRQCD and D234Sep 13 1999The masses of S- and P-wave heavy-light mesons are computed in quenched QCD using a classically and tadpole-improved action on anisotropic lattices. Of particular interest are the splittings among P-wave states, which have not yet been resolved experimentally; ... More
Photon operators for lattice gauge theoryJun 29 2018Jul 06 2018Photon operators with the proper $J^{PC}$ quantum numbers are constructed, including one made of elementary plaquettes. In compact U(1) lattice gauge theory, these explicit photon operators are shown to permit direct confirmation of the massive and massless ... More
A qubit model for U(1) lattice gauge theoryMay 23 2019A conceptually simple model for strongly interacting compact U(1) lattice gauge theory is expressed as operators acting on qubits. The number of independent gauge links is reduced to its minimum through the use of Gauss's law. The model can be implemented ... More
A Renormalization Group Study of Asymetrically Coupled Minimal ModelsMay 04 1998We investigate the renormalization group flows and fixed point structure of many coupled minimal models. The models are coupled two by two by energy-energy couplings. We take the general approach where the bare couplings are all taken to be independent. ... More
Freeze cast porous barium titanate for enhanced piezoelectric energy harvestingFeb 01 2019Energy harvesting is an important developing technology for a new generation of self-powered sensor networks. This paper demonstrates the significant improvement in the piezoelectric energy harvesting performance of barium titanate by forming highly aligned ... More
Why the Canis Major overdensity is not due to the Warp: analysis of its radial profile and velocitiesJul 19 2004Oct 20 2004In response to criticism by Momany et al. (2004), that the recently-identified Canis Major (CMa) overdensity could be simply explained by the Galactic warp, we present proof of the existence of a stellar population in the direction of CMa that cannot ... More
A radial velocity survey of low Galactic latitude structures: I. Kinematics of the Canis Major dwarf galaxyMar 31 2005Jul 01 2005As part of a radial velocity survey of low Galactic latitude structures that we undertook with the 2dF spectrograph on the AAT, we present the radial velocities of more than 1500 Red Giant Branch and Red Clump stars towards the centre of the Canis Major ... More
A kinematically selected, metal-poor stellar halo in the outskirts of M31Feb 28 2006Aug 18 2006We present evidence for a metal-poor, [Fe/H]$\sim-1.4$ $\sigma$=0.2 dex, stellar halo component detectable at radii from 10 kpc to 70 kpc, in our nearest giant spiral neighbor, the Andromeda galaxy. This metal-poor sample underlies the recently-discovered ... More
Hall effect characterization of electronic transition behind the metamagnetic transition in FeRhMay 23 2012Sep 13 2012The antiferromagnetic ground state and the metamagnetic transition to the ferromagnetic state of CsCl-ordered FeRh epilayers have been characterized using Hall and magnetoresistance measure- ments. On cooling into the ground state, the metamagnetic transition ... More
Temperature controlled motion of an antiferromagnet-ferromagnet interface within a dopant-graded FeRh epilayerDec 23 2014Chemically ordered B2 FeRh exhibits a remarkable antiferromagnetic-ferromagnetic phase transition that is first order. It thus shows phase coexistence, usually by proceeding though nucleation at random defect sites followed by propagation of phase boundary ... More
Status of Chiral-Scale Perturbation TheoryOct 05 2015Jun 07 2016Chiral-scale perturbation theory $\chi$PT$_\sigma$ has been proposed as an alternative to chiral $SU(3)_L\times SU(3)_R$ perturbation theory which explains the $\Delta I = 1/2$ rule for kaon decays. It is based on a low-energy expansion about an infrared ... More
A Model for Tracking Fronts of Stress-Induced Permeability EnhancementMay 15 2013Using an analogy to the classical Stefan problem, we construct evolution equations for the fluid pore pressure on both sides of a propagating stress-induced damage front. Closed form expressions are derived for the position of the damage front as a function ... More
Microwave resonance of the reentrant insulating quantum Hall phases in the 1st excited Landau LevelNov 24 2004We present measurements of the real diagonal microwave conductivity of the reentrant insulating quantum Hall phases in the first excited Landau level at temperatures below 50 mK. A resonance is detected around filling factor $\nu=2.58$ and weaker frequency ... More
Jupiter's Phase Variations from Cassini: a testbed for future direct-imaging missionsOct 24 2016We present phase curves of Jupiter from 0-140 degrees as measured in multiple optical bandpasses by Cassini/ISS during the Millennium flyby of Jupiter in late 2000 to early 2001. Phase curves are of interest for studying the energy balance of Jupiter ... More
A long-period Cepheid variable in the starburst cluster VdBH222Oct 22 2015Galactic starburst clusters play a twin role in astrophysics, serving as laboratories for the study of stellar physics and also delineating the structure and recent star formation history of the Milky Way. In order to exploit these opportunities we have ... More
A Keck/DEIMOS Kinematic Study of Andromeda IX: dark matter on the smallest galactic scalesJun 06 2005We present the results of a kinematic survey of the dwarf spheroidal satellite of M31, And-IX, which appears to be the lowest surface brightness and also the faintest galaxy (M_V = -8.3) found to date. Using Keck/DEIMOS spectroscopic data, we have measured ... More
Inside the whale: the structure and dynamics of the isolated Cetus dwarf spheroidalDec 11 2006This paper presents a study of the Cetus dwarf, an isolated dwarf galaxy within the Local Group. A matched-filter analysis of the INT/WFC imaging of this system reveals no evidence for significant tidal debris that could have been torn from the galaxy, ... More
Evidence of a first order phase transition between Wigner crystal and Bubble Phases of 2D electrons in higher Landau levelsJan 23 2004For filling factors $\nu$ in the range between 4.16 and 4.28, we simultaneously detect {\it two} resonances in the real diagonal microwave conductivity of a two--dimensional electron system (2DES) at low temperature $T \approx 35$ mK. We attribute the ... More
Wigner crystalization about $ν$=3Jul 08 2003We measure a resonance in the frequency dependence of the real diagonal conductivity, Re[$\sigma_{xx}$], near integer filling factor, $\nu=3$. This resonance depends strongly on $\nu$, with peak frequency $f_{pk} \approx 1.7$ GHz at $\nu=3.04$ or 2.92 ... More
Testing the jet quenching paradigm with an ultradeep observation of a steadily soft state black holeJun 03 2011We present ultradeep radio observations with the Expanded Very Large Array of 4U 1957+11, a Galactic black hole candidate X-ray binary known to exist in a persistent soft X-ray state. We derive a stringent upper limit of 11.4 micro-Jy beam^-1 (3 sigma) ... More
Microwave resonances of the bubble phases in 1/4 and 3/4 filled higher Landau levelsMay 09 2002Jul 31 2002We have measured the diagonal conductivity in the microwave regime of an ultrahigh mobility two dimensional electron system. We find a sharp resonance in Re[sigma_{xx}] versus frequency when nu > 4 and the partial filling of the highest Landau level, ... More
Know the Star, Know the Planet. III. Discovery of Late-Type Companions to Two Exoplanet Host StarsMar 04 2015We discuss two multiple star systems that host known exoplanets: HD 2638 and 30 Ari B. Adaptive optics imagery revealed an additional stellar companion to both stars. We collected multi-epoch images of the systems with Robo-AO and the PALM-3000 adaptive ... More
SCUBA observations of Hawaii 167Aug 23 2000We present the first submillimetre observations of the z=2.36 broad absorption line system Hawaii 167. Our observations confirm the hypothesis that Hawaii 167 contains a massive quantity of dust, the optical depth of which is sufficient to completely ... More
Dispersive treatment of $K_S\toγγ$ and $K_S\toγ\ell^+\ell^-$Sep 12 2016Nov 11 2016We analyse the rare kaon decays $K_S \to \gamma\gamma$ and $K_S \to \gamma\ell^+\ell^-$ $(\ell = e \mbox{ or } \mu)$ in a dispersive framework in which the weak Hamiltonian carries momentum. Our analysis extends predictions from lowest order $SU(3)_L\times ... More
Stop searches in flavourful supersymmetryApr 01 2016Natural realisations of supersymmetry require light stops ${\tilde t}_1$, making them a prime target of LHC searches for physics beyond the Standard Model. Depending on the kinematic region, the main search channels are ${\tilde t_1}\to t \tilde \chi^0_1$, ... More
Lipschitz behavior of the robust regularizationOct 01 2008To minimize or upper-bound the value of a function "robustly", we might instead minimize or upper-bound the "epsilon-robust regularization", defined as the map from a point to the maximum value of the function within an epsilon-radius. This regularization ... More
Level set methods for finding critical points of mountain pass typeJun 24 2009Jun 20 2010Computing mountain passes is a standard way of finding critical points. We describe a numerical method for finding critical points that is convergent in the nonsmooth case and locally superlinearly convergent in the smooth finite dimensional case. We ... More
Dispersive treatment of $K_S\toγγ$ and $K_S\toγ\ell^+\ell^-$Sep 12 2016We analyse the rare kaon decays $K_S \to \gamma\gamma$ and $K_S \to \gamma\ell^+\ell^-$ $(\ell = e \mbox{ or } \mu)$ in a dispersive framework in which the weak Hamiltonian carries momentum. Our analysis extends predictions from lowest order $SU(3)_L\times ... More
Improved models of upper-level wind for several astronomical observatoriesSep 20 2010An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant astronomical observatories and created mean profiles of ... More
A unitary "quantization commutes with reduction" map for the adjoint action of a compact Lie groupSep 25 2017Mar 28 2018Let $K$ be a simply connected compact Lie group and $T^{\ast}(K)$ its cotangent bundle. We consider the problem of "quantization commutes with reduction" for the adjoint action of $K$ on $T^{\ast}(K).$ We quantize both $T^{\ast}(K)$ and the reduced phase ... More
Permutation Tableaux and the Dashed Permutation Pattern 32-1Jul 28 2010We give a solution to a problem posed by Corteel and Nadeau concerning permutation tableaux of length n and the number of occurrences of the dashed pattern 32--1 in permutations on [n]. We introduce the inversion number of a permutation tableau. For a ... More
Correlation lengths of Wigner crystal order in two dimensional electron system at high magnetic fieldApr 03 2002Apr 03 2002The insulator terminating the fractional quantum Hall series at low Landau level filling \nu is generally taken to be a pinned Wigner crystal (WC), and exhibits a microwave resonance that is interpreted as a WC pinning mode. Systematically studying the ... More
A dwarf nova in the globular cluster M13Mar 23 2011May 06 2011Dwarf novae in globular clusters seem to be rare with only 13 detections in the 157 known Galactic globular clusters. We report the identification of a new dwarf nova in M13, the 14th dwarf nova identified in a globular cluster to date. Using the 2m Faulkes ... More
Neutron scattering from a coordination polymer quantum paramagnetMar 22 2006Mar 23 2006Inelastic neutron scattering measurements are reported for a powder sample of the spin-1/2 quantum paramagnet $\rm Cu(Quinoxaline)Br_2$. Magnetic neutron scattering is identified above an energy gap of 1.9 meV. Analysis of the sharp spectral maximum at ... More
Evidence for TeV gamma ray emission from TeV J2032+4130 in Whipple archival dataMay 26 2004A reanalysis of data taken on the Cygnus region in 1989-90 using the Whipple Observatory atmospheric Cherenkov imaging telescope confirms the existence of the TeV J2032+4130 source reported by the Crimean Astrophysical Observatory and published by the ... More
The kinematic identification of a thick stellar disc in M31Oct 25 2010Dec 21 2010We present the first characterization of a thick disc component in the Andromeda galaxy (M31) using kinematic data from the DEIMOS multi-object spectrograph instrument on Keck II. Using 21 fields in the South West of the galaxy, we measure the lag of ... More
The nucleon's strange electromagnetic and scalar matrix elementsOct 03 2002Quenched lattice QCD simulations and quenched chiral perturbation theory are used together for this study of strangeness in the nucleon. Dependences of the matrix elements on strange quark mass, valence quark mass and momentum transfer are discussed in ... More