Results for "Simon J. Murphy"

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The potential for super-Nyquist asteroseismology with TESSAug 11 2015The perfect 30-min cadence of the full-frame images from the Transiting Exoplanet Survey Satellite (TESS) will impose a hard Nyquist limit of 24 d$^{-1}$ ($\approx 278$ $\mu$Hz). This will be problematic for asteroseismology of stars with oscillation ... More
An examination of some characteristics of Kepler Short and Long Cadence DataJan 30 2012A close comparison of Kepler short- and long-cadence data released prior to 2011 Nov 1 has shown some subtle differences that make the short-cadence data superior to their long-cadence counterparts. The inevitable results of a faster sampling rate are ... More
Gaia's view of the $λ$ Boo star puzzleDec 05 2016The evolutionary status of the chemically peculiar class of $\lambda$ Boo stars has been intensely debated. It is now agreed that the $\lambda$ Boo phenomenon affects A stars of all ages, from star formation to the terminal age main sequence, but the ... More
Deriving the orbital properties of pulsators in binary systems through their light arrival time delaysApr 20 2015We present the latest developments to the phase modulation method for finding binaries among pulsating stars. We demonstrate how the orbital elements of a pulsating binary star can be obtained analytically, that is, without converting time delays to radial ... More
Comparison of Spreadsheets with other Development Tools (limitations, solutions, workarounds and alternatives)Jan 24 2008The spreadsheet paradigm has some unique risks and challenges that are not present in more traditional development technologies. Many of the recent advances in other branches of software development have bypassed spreadsheets and spreadsheet developers. ... More
EuSpRIG 2006 Commercial Spreadsheet ReviewFeb 29 2008This management summary provides an outline of a commercial spreadsheet review process. The aim of this process is to ensure remedial or enhancement work can safely be undertaken on a spreadsheet with a commercially acceptable level of risk of introducing ... More
Spectrophotometric Libraries, Revised Photonic Passbands and Zero-points for UBVRI, Hipparcos and Tycho PhotometryDec 12 2011We have calculated improved photonic passbands for the UBV RI, Hipparcos and Tycho Hp,BT,VT standard systems using the extensive spectrophotometric libraries of NGSL and MILES. Using the Hp passband, we adjusted the absolute flux levels of stars in the ... More
New low-mass members of the Octans stellar association and an updated 30-40 Myr lithium ageNov 20 2014The Octans association is one of several young stellar moving groups recently discovered in the Solar neighbourhood, and hence a valuable laboratory for studies of stellar, circumstellar disc and planetary evolution. However, a lack of low-mass members ... More
Towards a complete census of young stars in the solar neighbourhood with SkyMapperJun 10 2008In this contribution we outline plans for identifying and characterising numerous young, low-mass stars within 150 pc of the Sun using the new SkyMapper telescope and Southern Sky Survey. We aim to learn more about the star formation history of the solar ... More
Super-Nyquist asteroseismology with the Kepler Space TelescopeDec 21 2012Barycentric corrections made to the timing of Kepler observations, necessitated by variations in light arrival time at the satellite, break the regular time-sampling of the data -- the time stamps are periodically modulated. A consequence is that Nyquist ... More
WISE J080822.18-644357.3 - a 45 Myr-old accreting M dwarf hosting a pre-transitional discMar 13 2017WISE J080822.18-644357.3 (WISE J0808-6443) was recently identified as a new M dwarf debris disc system and a candidate member of the 45 Myr-old Carina association. Given that the strength of its infrared excess ($L_{\mathrm{IR}}/L_{\mathrm{\star}}$ ~ ... More
Re-examining the membership and origin of the Epsilon Cha associationMay 17 2013Jul 23 2013We present a comprehensive investigation of the Epsilon Chamaeleontis association (Epsilon Cha), one of several young moving groups spread across the southern sky. We re-assess the putative membership of Epsilon Cha using the best-available proper motion ... More
New members of the TW Hydrae Association and two accreting M-dwarfs in Scorpius-CentaurusJul 29 2015We report the serendipitous discovery of several young mid-M stars found during a search for new members of the 30-40 Myr-old Octans Association. Only one of the stars may be considered a possible Octans(-Near) member. However, two stars have proper motions, ... More
A stellar census of the nearby, young 32 Orionis groupFeb 28 2017The 32 Orionis group was discovered almost a decade ago and despite the fact that it represents the first northern, young (age ~ 25 Myr) stellar aggregate within 100 pc of the Sun ($d \simeq 93$ pc), a comprehensive survey for members and detailed characterisation ... More
RX J0942.7-7726AB: an isolated pre-main sequence wide binaryMay 07 2012We report the discovery of two young M-dwarfs, RX J0942.7-7726 (M1) and 2MASS J09424157-7727130 (M4.5), that were found only 42 arcsec apart in a survey for pre-main sequence stars surrounding the open cluster eta Chamaeleontis. Both stars have congruent ... More
First detection of a low-mass stellar halo around the young open cluster Eta ChamaeleontisMay 18 2010We have identified several lithium-rich low-mass (0.08<M<0.3 Msun) stars within 5.5 deg of the young open cluster Eta Chamaeleontis, nearly four times the radius of previous search efforts. Of these stars we propose 4 new probable cluster members, and ... More
Revealing the Chamaeleon: First detection of a low-mass stellar halo around the young open cluster Eta ChamaeleontisDec 13 2010We have identified several lithium-rich low-mass (0.08<M<0.3 Msun). stars within 5.5 deg of the young open cluster Eta Chamaeleontis, nearly four times the radius of previous search efforts. We propose 4 new probable cluster members and 3 possible members ... More
FM stars II: a Fourier view of pulsating binary stars -- determining binary orbital parameters photometrically for highly eccentric casesApr 20 2015Continuous and precise space-based photometry has made it possible to measure the orbital frequency modulation of pulsating stars in binary systems with extremely high precision over long time spans. Frequency modulation caused by binary orbital motion ... More
A planet in an 840-d orbit around a Kepler main-sequence A star found from phase modulation of its pulsationsAug 09 2016Aug 11 2016We have detected a 12 M$_{\rm Jup}$ planet orbiting in or near the habitable zone of a main-sequence A star via the pulsational phase shifts induced by orbital motion. The planet has an orbital period of $840\pm20$ d and an eccentricity of 0.15. All known ... More
Finding binaries from phase modulation of pulsating stars with Kepler. IV. Detection limits and radial velocity verificationJul 26 2016Aug 01 2016We explore the detection limits of the phase modulation (PM) method of finding binary systems among multi-periodic pulsating stars. The method is an attractive way of finding non-transiting planets in the habitable zones of intermediate mass stars, whose ... More
A nearby young M dwarf with a wide, possibly planetary-mass companionJan 22 2016We present the identification of two previously known young objects in the solar neighbourhood as a likely very wide binary. TYC 9486-927-1, an active, rapidly rotating early-M dwarf, and 2MASS J21265040-8140293, a low-gravity L3 dwarf previously identified ... More
Exploring the Virgo Stellar Stream with SEKBO Survey RR Lyrae StarsOct 01 2008A subset of the RR Lyrae (RRL) candidates identified from the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey data has been followed up photometrically (n=106) and spectroscopically (n=51). Period and light curve fitting reveals a 24 +/_ 7% contamination ... More
Episodic disk accretion in the halo of the 'old' Pre-Main Sequence cluster Eta ChamaeleontisNov 16 2010Nov 26 2010We present multi-epoch medium-resolution observations of two M4.5 candidate members in the halo of the ~8 Myr Eta Chamaeleontis open cluster. Over six months of observations both stars exhibited variations in their H-alpha line profiles on timescales ... More
Pulsational amplitude growth of the star KIC 3429637 (HD 178875) in the context of Am and rho Puppis starsSep 07 2012KIC 3429637 (HD 178875) is a delta Sct star whose light-curve shows continuous pulsational amplitude growth in Kepler Mission photometry. Analysis of the three largest amplitude peaks in the Fourier transform indicates different growth rates for all three. ... More
Validation of the Frequency Modulation technique applied to the pulsating delta Sct - gamma Dor eclipsing binary star KIC 8569819Oct 31 2014KIC 8569819 is an eclipsing binary star with an early F primary and G secondary in a 20.85-d eccentric orbit. The primary is a delta Sct - gamma Dor star pulsating in both p modes and g modes. Using 4 years of Kepler Mission photometric data we independently ... More
Amplitude modulation in $δ$ Sct stars: statistics from an ensemble study of Kepler targetsMay 12 2016We present the results of a search for amplitude modulation of pulsation mode frequencies in 983 $\delta$ Sct stars, which have effective temperatures between 6400 $\leq T_{\rm eff} \leq$ 10 000 K in the Kepler Input Catalogue and were continuously observed ... More
A unifying explanation of complex frequency spectra of gamma Dor, SPB and Be stars: combination frequencies and highly non-sinusoidal light curvesApr 16 2015There are many Slowly Pulsating B (SPB) stars and gamma Dor stars in the Kepler Mission data set. The light curves of these pulsating stars have been classified phenomenologically into stars with symmetric light curves and with asymmetric light curves. ... More
Metal-Rich SX Phe stars in the Kepler FieldNov 30 2016A spectroscopic and photometric analysis has been carried out for thirty-two candidate SX_Phe variable blue straggler stars in the Kepler-field (Balona & Nemec 2012). Radial velocities (RVs), space motions (U,V,W), projected rotation velocities (v sin ... More
Finding binaries among Kepler pulsating stars from phase modulation of their pulsationsApr 22 2014We present a method for finding binaries among pulsating stars that were observed by the Kepler Mission. We use entire four-year light curves to accurately measure the frequencies of the strongest pulsation modes, then track the pulsation phases at those ... More
Copious Amounts of Hot and Cold Dust Orbiting the Main Sequence A-type Stars HD 131488 and HD 121191Aug 13 2013We report two new dramatically dusty main sequence stars: HD 131488 (A1V) and HD 121191 (A8V). HD 131488 is found to have substantial amounts of dust in its terrestrial planet zone (L_IR/L_bol~4x10^-3), cooler dust further out in its planetary system, ... More
Rapid disappearance of a warm, dusty circumstellar diskJul 05 2012Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation ... More
A search for non-pulsating, chemically normal stars in the $δ$ Scuti instability strip using Kepler dataDec 23 2014We identify stars in the $\delta$ Sct instability strip that do not pulsate in p modes at the 50-$\mu$mag limit, using Kepler data. Spectral classification and abundance analyses from high-resolution spectroscopy allow us to identify chemically peculiar ... More
Asteroseismology of 16000 Kepler red giants: Global oscillation parameters, Masses, and radiiFeb 13 2018The Kepler mission has provided exquisite data to perform an ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission ... More
The Planet Formation Potential Around a 45 Myr old Accreting M DwarfDec 10 2018Debris disk detections around M dwarfs are rare, and so far no gas emission has been detected from an M dwarf debris disk. This makes the 45 Myr old M dwarf WISEJ080822.18-644357.3 a bit of a curiosity; it has a strong infrared excess at an age beyond ... More
Asteroseismology of 16000 Kepler Red Giants: Global Oscillation Parameters, Masses, and RadiiFeb 13 2018Apr 03 2018The Kepler mission has provided exquisite data to perform an ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission ... More
Echelle diagrams and period spacings of g modes in gamma Doradus stars from four years of Kepler observationsNov 07 2014We use photometry from the Kepler Mission to study oscillations in gamma Doradus stars. Some stars show remarkably clear sequences of g modes and we use period echelle diagrams to measure period spacings and identify rotationally split multiplets with ... More
Bayesian Intent Prediction in Object Tracking Using Bridging DistributionsAug 25 2015Feb 04 2016In several application areas, such as human computer interaction, surveillance and defence, determining the intent of a tracked object enables systems to aid the user/operator and facilitate effective, possibly automated, decision making. In this paper, ... More
Asteroseismic measurement of surface-to-core rotation in a main sequence A star, KIC 11145123May 01 2014Jul 14 2014We have discovered rotationally split core g-mode triplets and surface p-mode triplets and quintuplets in a terminal age main sequence A star, KIC 11145123, that shows both $\delta$ Sct p-mode pulsations and $\gamma$ Dor g-mode pulsations. This gives ... More
Binary star detectability in $Kepler$ data from phase modulation of different types of oscillationsMay 11 2016Detecting binary stars in photometric time series is traditionally done by measuring eclipses. This requires the orbital plane to be aligned with the observer. A new method without that requirement uses stellar oscillations to measure delays in the light ... More
A Spectroscopic and Photometric Investigation of the Mercury-Manganese Star KIC 6128830Nov 22 2017The advent of space-based photometry provides the opportunity for the first precise characterizations of variability in Mercury-Manganese (HgMn/CP3) stars, which might advance our understanding of their internal structure. We have carried out a spectroscopic ... More
The Solar Neighborhood. XXVI. AP Col: The Closest (8.4 pc) Pre-Main-Sequence StarAug 26 2011We present the results of a multi-technique investigation of the M4.5Ve flare star AP Col, which we discover to be the nearest pre-main-sequence star. These include astrometric data from the CTIO 0.9m, from which we derive a proper motion of 342.0+/-0.5 ... More
Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binariesNov 30 2017The orbital parameters of binaries at intermediate periods ($10^2$--$10^3$ d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to {\it Kepler} light curves ... More
Limits on a Gravitational Field Dependence of the Proton--Electron Mass Ratio from H$_2$ in White Dwarf StarsSep 03 2014Spectra of molecular hydrogen (H$_2$) are employed to search for a possible proton-to-electron mass ratio ($\mu$) dependence on gravity. The Lyman transitions of H$_2$, observed with the Hubble Space Telescope towards white dwarf stars that underwent ... More
Spectroscopic and asteroseismic analysis of the remarkable main-sequence A star KIC 11145123Jun 14 2017A spectroscopic analysis was carried out to clarify the properties of KIC 11145123 -- the first main-sequence star with a determination of core-to-surface rotation -- based on spectra observed with the High Dispersion Spectrograph (HDS) of the Subaru ... More
HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole modeJul 13 2016We present an analysis of the first Kepler K2 mission observations of a rapidly oscillating Ap (roAp) star, HD 24355 ($V=9.65$). The star was discovered in SuperWASP broadband photometry with a frequency of 224.31 d$^{-1}$, (2596.18 $\mu$Hz; $P = 6.4$ ... More
Asteroseismology of 1523 misclassified red giants using $\textit{Kepler}$ dataAug 20 2016We analysed solar-like oscillations in 1523 $\textit{Kepler}$ red giants which have previously been misclassified as subgiants, with predicted $\nu_{\rm max}$ values (based on the Kepler Input Catalogue) between 280$\mu$Hz to 700$\mu$Hz. We report the ... More
Kepler Fourier concepts: The performance of the Kepler data pipelineNov 21 2012Apr 10 2013Given the extreme precision attainable with the Kepler Space Telescope, the mitigation of instrumental artefacts is very important. In an earlier paper (Murphy 2012), the characteristics of Kepler data were discussed in light of their effect on asteroseismology. ... More
Identifying Variations to the IMF at High-$z$ Through Deep Radio SurveysSep 09 2010In this article I briefly describe how deep radio surveys may provide a means to identify variations in the upper end of the initial mass function (IMF) in star-forming galaxies at high redshifts (i.e., $z\gtrsim$3). At such high redshifts, I argue that ... More
Domain Wall Fermion Simulations with the Exact One-Flavor AlgorithmNov 01 2016Nov 22 2016As algorithmic developments have driven down the cost of simulating degenerate light quark flavors the relative cost of simulating single quark flavors with the Rational Hybrid Monte Carlo (RHMC) algorithm has become more expensive. TWQCD has proposed ... More
Asteroseismic measurement of slow, nearly-uniform surface-to-core rotation in the main sequence F star KIC 9244992Dec 17 2014We have found a rotationally split series of core g-mode triplets and surface p-mode multiplets in a main sequence F star, KIC 9244992. Comparison with models shows that the star has a mass of about 1.45 M$_\odot$, and is at an advanced stage of main ... More
Modelling Kepler Red Giants in Eclipsing Binaries:Calibrating the Mixing Length Parameter with AsteroseismologyDec 05 2017Stellar models rely on a number of free parameters. High-quality observations of eclipsing binary stars observed by Kepler offer a great opportunity to calibrate model parameters for evolved stars. Our study focuses on six Kepler red giants with the goal ... More
Asteroseismology of KIC 7107778: a binary comprising almost identical subgiantsJan 27 2018We analyze an asteroseismic binary system: KIC 7107778, a non-eclipsing, unresolved target, with solar-like oscillations in both components. We used \emph{Kepler} short cadence time series spanning nearly two years to obtain the power spectrum. Oscillation ... More
Domain Wall Fermion Simulations with the Exact One-Flavor AlgorithmNov 01 2016As algorithmic developments have driven down the cost of simulating degenerate light quark pairs the relative cost of simulating single quark flavors with the Rational Hybrid Monte Carlo (RHMC) algorithm has become more expensive. TWQCD has proposed an ... More
The Far-Infrared Radio Correlation at High-z: Prospects for the SKAOct 07 2009In this conference proceedings article I summarize the recent work of Murphy (2009) which presents physically motivated predictions for the evolution of the Far-Infrared--radio correlation as a function of redshift arising from variations in the cosmic-ray ... More
Derived equivalence classification of m-cluster tilted algebras of type AJul 24 2008We use the maximal faces of the $m$-cluster complex of type A to describe the m-cluster tilted algebras of type A as quivers with relations. We then classify connected components of m-cluster tilted algebras of type A up to derived equivalence using tilting ... More
The Far-Infrared--Radio Correlation at High Redshifts: Physical Considerations and Prospects for the Square Kilometer ArraySep 30 2009(Abridged) I present a predictive analysis for the behavior of the FIR--radio correlation as a function of redshift in light of the deep radio continuum surveys which may become possible using the SKA. To keep a fixed ratio between the FIR and predominantly ... More
The Role of Merger Stage on Galaxy Radio Spectra in Local Infrared-Bright Starburst GalaxiesAug 20 2013An investigation of the steep, high-frequency (i.e., ~12 GHz) radio spectra among a sample of 31 local infrared-bright starburst galaxies is carried out in light of their HST-based merger classifications. Radio data covering as many as 10 individual bands ... More
An evaluation of the membership probability of 212 $λ$ Boo stars: I. A CatalogueAug 14 2015Aug 26 2015The literature on the $\lambda$ Boo stars has grown to become somewhat heterogenous, as different authors have applied different criteria across the UV, optical and infrared regions to determine the membership status of $\lambda$ Boo candidates. We aim ... More
Large amplitude change in spot-induced rotational modulation of the Kepler Ap star KIC 2569073Jul 18 2017An investigation of the 200 $\times$ 200 pixel 'superstamp' images of the centres of the open clusters NGC 6791 and NGC 6819 allows for the identification and study of many variable stars that were not included in the Kepler target list. KIC 2569073 (V=14.22), ... More
KIC 3749404: A heartbeat Star with Rapid Apsidal Advance Indicative of a Tertiary ComponentAug 08 2016Heartbeat stars are eccentric (e > 0.2) ellipsoidal variables whose light curves resemble a cardiogram. We present the observations and corresponding model of KIC 3749404, a highly eccentric (e = 0.66), short period (P = 20.3 d) heartbeat star with tidally ... More
The Most Metal-Poor Stars. I. Discovery, Data, and Atmospheric ParametersAug 15 2012We report the discovery of 34 stars in the Hamburg/ESO Survey for metal-poor stars and the Sloan Digital Sky Survey that have [Fe/H] < -3.0. Their median and minimum abundances are [Fe/H] = -3.1 and -4.1, respectively, while 10 stars have [Fe/H] < -3.5. ... More
Dust-reddening and gravitational lensing of SDSS QSOs due to foreground damped Lyman-alpha systemsMay 25 2004Sep 06 2004We use Sloan Digital Sky Survey Data Release 2 QSO spectra to constrain the dust-reddening caused by intervening damped Lyman-alpha systems (DLAs). Comparing the spectral index distribution of a 70 sight-line DLA sample with that of a large control sample ... More
Surface waves and surface stability for a pre-stretched, unconstrained, non-linearly elastic half-spaceDec 08 2008An unconstrained, non-linearly elastic, semi-infinite solid is maintained in a state of large static plane strain. A power-law relation between the pre-stretches is assumed and it is shown that this assumption is well-motivated physically and is likely ... More
A consistent formalism for the Thomas-Ehrman Level DisplacementApr 26 2007Usage of the Thomas-Ehrman Level Displacement formalism has been examined. Mistakes and inconsistencies are found in several papers, being repeated in subsequent works. Here, we present a complete formalism with a consistent set of definitions. Full algorithms ... More
Differential Calculi over Quantum Groups and Twisted Cyclic CocyclesOct 18 2001Oct 19 2001We study some aspects of the theory of non-commutative differential calculi over complex algebras, especially over the Hopf algebras associated to compact quantum groups in the sense of S.L. Woronowicz. Our principal emphasis is on the theory of twisted ... More
A sharper view of the outer Galaxy at 1420 and 408 MHz from the Canadian Galactic Plane Survey II: The catalogue of extended radio sourcesMay 18 2007A new catalogue of extended radio sources has been prepared based on arcminute-resolution 1420 MHz images from the Canadian Galactic Plane Survey (CGPS). The new catalogue provides both 1420 MHz and 408 MHz flux density measurements on sources found near ... More
Quantum groups, differential calculi and the eigenvalues of the LaplacianNov 05 2001We study *-differential calculi over compact quantum groups in the sense of S.L. Woronowicz. Our principal results are the construction of a Hodge operator commuting with the Laplacian, the derivation of a corresponding Hodge decomposition of the calculus ... More
A High-Resolution Spectroscopic Search for the Remaining Donor for Tycho's SupernovaOct 09 2012In this paper, we report on our analysis using Hubble Space Telescope astrometry and Keck-I HIRES spectroscopy of the central six stars of Tycho's supernova remnant (SN 1572). With these data, we measured the proper motions, radial velocities, rotational ... More
Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas KinematicsMay 19 2014We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest that they contain ... More
The square root law and structure of finite ringsMay 29 2014Let $R$ be a finite ring and define the hyperbola $H=\{(x,y) \in R \times R: xy=1 \}$. Suppose that for a sequence of finite odd order rings of size tending to infinity, the following "square root law" bound holds with a constant $C>0$ for all non-trivial ... More
Annihilation Radiation in the GalaxyJul 12 2001Observations of annihilation radiation in the Galaxy are briefly reviewed. We summarize astrophysical mechanisms leading to positron production, and recent estimates for production rates from nova and supernova nucleosynthesis in the Galaxy. The physical ... More
Coherent phonon scattering effects on thermal transport in thin semiconductor nanowiresJan 29 2007Feb 26 2007The thermal conductance by phonons of a quasi-one-dimensional solid with isotope or defect scattering is studied using the Landauer formalism for thermal transport. The conductance shows a crossover from localized to Ohmic behavior, just as for electrons, ... More
Co-Amenability of compact quantum groupsOct 26 2000We study the concept of co-amenability for a compact quantum group. Several conditions are derived that are shown to be equivalent to it. Some consequences of co-amenability that we obtain are faithfulness of the Haar integral and automatic norm-boundedness ... More
Low-energy excitations of a boson pair in a double-well trapMar 17 2008The states of a boson pair in a one-dimensional double-well potential are investigated. Properties of the ground and lowest excited states of this system are studied, including the two-particle wavefunction, momentum pair distribution and entanglement. ... More
GRBlog: A Database for Gamma-Ray BurstsDec 11 2003GRBlog is an on-line database providing researchers with quick access to all information reported in the GCN Circulars. Users of the GRBlog web site ( can search the circulars and produce afterglow light curve plots, or ... More
C*-Algebras with the Approximate Positive Factorization PropertyJun 28 1995We say that a unital C*-algrebra A has the approximate positive factorization property (APFP) if every element of A is a norm limit of products of positive elements of A. (There is also a definition for the nonunital case.) T. Quinn has recently shown ... More
Amenability and co-amenability of algebraic quantum groupsNov 02 2001Mar 04 2002We define concepts of amenability and co-amenability for algebraic quantum groups in the sense of A. Van Daele. We show that co-amenability of an algebraic quantum group always implies amenability of its dual. Various necessary and/or sufficient conditions ... More
Exploring the Decision Forest: An Empirical Investigation of Occam's Razor in Decision Tree InductionMar 01 1994We report on a series of experiments in which all decision trees consistent with the training data are constructed. These experiments were run to gain an understanding of the properties of the set of consistent decision trees and the factors that affect ... More
Impact of instrumental systematic errors on fine-structure constant measurements with quasar spectraSep 15 2014Nov 18 2014We present a new `supercalibration' technique for measuring systematic distortions in the wavelength scales of high resolution spectrographs. By comparing spectra of `solar twin' stars or asteroids with a reference laboratory solar spectrum, distortions ... More
Amenability and co-amenability of algebraic quantum groups IINov 02 2001We continue our study of the concepts of amenability and co-amenability for algebraic quantum groups in the sense of A. Van Daele and our investigation of their relationship with nuclearity and injectivity. One major tool for our analysis is that every ... More
NLO and NNLO Low Energy Constants for $SU(2)$ Chiral Perturbation TheoryNov 13 2015We have performed global fits of $f_{\pi}$ and $m_{\pi}$, from a variety of RBC-UKQCD domain wall fermion ensembles, to $SU(2)$ partially quenched chiral perturbation theory at NNLO. We report values for 9 NLO and 8 linearly independent combinations of ... More
Revealing Substructure in the Galactic Halo - The SEKBO RR Lyrae SurveyNov 15 2007We present a search for RR Lyrae variable stars from archival observations of the Southern Edgeworth-Kuiper Belt Object survey. The survey covers 1675 square degrees along the ecliptic to a mean depth of V=19.5, i.e. a heliocentric distance of ~50kpc ... More
Theory and evidence of global Rossby waves in upper main-sequence stars: r-mode oscillations in many Kepler starsNov 14 2017Asteroseismic inference from pressure modes (p modes) and buoyancy, or gravity, modes (g modes) is ubiquitous for stars across the Hertzsprung--Russell diagram. Until now, however, discussion of r modes (global Rossby waves) has been rare. Here we derive ... More
Psychological Frameworks for Persuasive Information and Communications TechnologiesAug 28 2018When developing devices to encourage positive change in users, social psychology can offer useful conceptual resources. This article outlines three major theories from the discipline and discusses their implications for designing persuasive technologies. ... More
Charge and orbital order in frustrated Pb3Mn7O15Jan 13 2012Mar 28 2012The candidate magnetoelectric Pb3Mn7O15 has a structure consisting of 1/3 filled Kagome layers linked by ribbons of edge-sharing octahedra in the stacking direction. Previous reports have indicated a complex hexagonal-orthorhombic structural transition ... More
Slepian functions and their use in signal estimation and spectral analysisSep 29 2009It is a well-known fact that mathematical functions that are timelimited (or spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the finite precision of measurement and computation unavoidably bandlimits our observation and modeling ... More
Programming quantum computers using 3-D puzzles, coffee cups, and doughnutsSep 21 2016The task of programming a quantum computer is just as strange as quantum mechanics itself. But it now looks like a simple 3D puzzle may be the future tool of quantum software engineers.
Classical Control of Large-Scale Quantum ComputersMay 20 2014The accelerated development of quantum technology has reached a pivotal point. Early in 2014, several results were published demonstrating that several experimental technologies are now accurate enough to satisfy the requirements of fault-tolerant, error ... More
Two loop Kahler potential in beta-deformed N=4 SYM theoryMay 23 2008Aug 06 2008In N=2 superconformal field theories the Kahler potential is known to be tree level exact. The beta-deformation of N=4 SU(N) SYM reduces the amount of supersymmetry to N=1, allowing for non-trivial, superconformal loop corrections to the Kahler potential. ... More
Coevality in Young Eclipsing BinariesApr 29 2017The ages of the components in very short period pre-main sequence (PMS) binaries are essential to an understanding of their formation. We considered a sample of 7 PMS eclipsing binaries (EBs) with ages 1 to 6.3 MY and component masses 0.2 to 1.4 Msun ... More
Contribution to Temporal Fault Tree Analysis without Modularization and Transformation into the State SpaceMay 18 2015Background: Fault tree analysis (FTA) is a well established method for qualitative as well as probabilistic reliability and safety analysis. As a Boolean model it does not support modelling of dynamic effects like sequence dependencies between fault events. ... More
Performing Quantum Computing Experiments in the CloudMay 18 2016Sep 01 2016Quantum computing technology has reached a second renaissance in the past five years. Increased interest from both the private and public sector combined with extraordinary theoretical and experimental progress has solidified this technology as a major ... More
A constraint on a varying proton--electron mass ratio 1.5 billion years after the Big BangJan 22 2015A molecular hydrogen absorber at a lookback time of 12.4 billion years, corresponding to 10$\%$ of the age of the universe today, is analyzed to put a constraint on a varying proton--electron mass ratio, $\mu$. A high resolution spectrum of the J1443$+$2724 ... More
Reply to: Critical revision of the ZEPLIN-I sensitivity to WIMP interactionsJan 30 2007Recent objections (Phys.Lett. B 637, 156) to the published Zeplin I limit (Astropart. Phys 23, 444) are shown to arise from misunderstandings of the calibration data and procedure, and a misreading of the data in one of the referenced papers.
Boson Pairs in a One-dimensional Split TrapJul 06 2007We describe the properties of a pair of ultracold bosonic atoms in a one-dimensional harmonic trapping potential with a tunable zero-ranged barrier at the trap centre. The full characterisation of the ground state is done by calculating the reduced single-particle ... More
Applying Monte Carlo configuration interaction to transition metal dimers: exploring the balance between static and dynamic correlationMay 22 2014We calculate potential curves for transition metal dimers using Monte Carlo configuration interaction (MCCI). These results, and their associated spectroscopic values, are compared with experimental and computational studies. The multireference nature ... More
Delayed X- and Gamma-Ray Line Emission from Solar Flare RadioactivityApr 14 2006We have studied the radioactive line emission expected from solar active regions after large flares, following the production of long-lived radioisotopes by nuclear interactions of flare-accelerated ions. This delayed X- and gamma-ray line emission can ... More
Generating of an electric potential on the Moon by Cosmic rays and Solar Wind?Aug 12 2010We investigate the possibility that the Moon develops an electric potential originating from the impinging particles on the Moon from cosmic rays and solar wind. The investigation includes all experimental data of the flux of charged particle for energies ... More
A search for high redshift molecular absorption lines toward millimetre-loud, optically faint quasarsMar 04 2003We describe initial results of a search for redshifted molecular absorption toward four millimetre-loud, optically faint quasars. A wide frequency bandwidth of up to 23 GHz per quasar was scanned using the Swedish-ESO Sub-millimetre Telescope at La Silla. ... More
H_2-bearing damped Lyman-alpha systems as tracers of cosmological chemical evolutionOct 15 2003Dec 09 2003The chemical abundances in damped Lyman-alpha systems (DLAs) show more than 2 orders of magnitude variation at a given epoch, possibly because DLAs arise in a wide variety of host galaxies. This could significantly bias estimates of chemical evolution. ... More