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The Effect of Combined Magnetic Geometries on Thermally Driven Winds I: Interaction of Dipolar and Quadrupolar FieldsJul 13 2017Cool stars with outer convective envelopes are observed to have magnetic fields with a variety of geometries, which on large scales are dominated by a combination of the lowest order fields such as the dipole, quadrupole and octupole modes. Magnetised ... More

The Effect of Combined Magnetic Geometries on Thermally Driven Winds II: Dipolar, Quadrupolar and Octupolar TopologiesJan 23 2018Mar 21 2018During the lifetime of sun-like or low mass stars a significant amount of angular momentum is removed through magnetised stellar winds. This process is often assumed to be governed by the dipolar component of the magnetic field. However, observed magnetic ... More

The Effect of Magnetic Variability on Stellar Angular Momentum Loss II: The Sun, 61 Cygni A, $ε$ Eridani, $ξ$ Bootis A and $τ$ Bootis AMar 23 2019The magnetic fields of low-mass stars are observed to be variable on decadal timescales, ranging in behaviour from cyclic to stochastic. The changing strength and geometry of the magnetic field should modify the efficiency of angular momentum loss by ... More

The Effect of Magnetic Variability on Stellar Angular Momentum Loss I: The Solar Wind Torque During Sunspot Cycles 23 & 24Jul 31 2018Aug 23 2018The rotational evolution of cool stars is governed by magnetised stellar winds which slow the stellar rotation during their main sequence lifetimes. Magnetic variability is commonly observed in Sun-like stars, and the changing strength and topology of ... More

Asymptotic properties of the C-MetricMar 07 2010The aim of this article is to analyze the asymptotic properties of the C-metric, using a general method specified in work of Tafel and coworkers, [1], [2], [3]. By finding an appropriate conformal factor $\Omega$, it allows the investigation of the asymptotic ... More

The energy dependence of $p_t$ angular correlations inferred from mean-$p_{t}$ fluctuation scale dependence in heavy ion collisions at the SPS and RHICMay 17 2006Dec 07 2006We present the first study of the energy dependence of $p_t$ angular correlations inferred from event-wise mean transverse momentum $<p_{t} >$ fluctuations in heavy ion collisions. We compare our large-acceptance measurements at CM energies $\sqrt{s_{NN}} ... More

The multiplicity dependence of inclusive $p_t$ spectra from p-p collisions at $\sqrt{s}$ = 200 GeVJun 23 2006Jun 26 2006We report measurements of transverse momentum $p_t$ spectra for ten event multiplicity classes of p-p collisions at $\sqrt{s} = 200$ GeV. By analyzing the multiplicity dependence we find that the spectrum shape can be decomposed into a part with amplitude ... More

Multi-Strange Baryon Production in Au-Au collisions at sqrt(s_NN) = 130 GeVJul 30 2003The transverse mass spectra and mid-rapidity yields for $\Xi$s and $\Omega$s plus their anti-particles are presented. The 10% most central collision yields suggest that the amount of multi-strange particles produced per produced charged hadron increases ... More

Transverse momentum and collision energy dependence of high $p_{T}$ hadron suppression in Au+Au collisions at ultrarelativistic energiesMay 19 2003Oct 29 2003We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at \sqrtsNN=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for $5\lt\pT\lt12$ GeV/c. The collision ... More

Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at FermilabSep 25 1997We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely ... More

Production of $e^+e^-$ Pairs Accompanied by Nuclear Dissociation in Ultra-Peripheral Heavy Ion CollisionApr 07 2004Jul 19 2004We present the first data on $e^+e^-$ pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, ... More

Pion-Kaon correlations in central Au+Au collisions at $\sqrt{s_{NN}} = 130$ GeVJul 31 2003May 24 2004Pion-kaon correlation functions are constructed from central Au+Au data taken at $\sqrt{s_{NN}} = 130$ GeV. The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e. transverse flow, ... More

rho^0 Production and Possible Modification in Au+Au and p+p Collisions at sqrt(s_NN) = 200 GeVJul 28 2003Mar 08 2004We report results on rho(770)^0 -> pi+pi- production at midrapidity in p+p and peripheral Au+Au collisions at sqrt(s_NN) = 200 GeV. This is the first direct measurement of rho(770)^0 -> pi+pi- in heavy-ion collisions. The measured rho^0 peak in the invariant ... More

Evidence from d+Au measurements for final-state suppression of high $p_T$ hadrons in Au+Au collisions at RHICJun 17 2003Aug 18 2003We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high $p_T$) in minimum bias and central d+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The inclusive yield ... More

Rapidity and Centrality Dependence of Proton and Anti-proton Production from Au+Au Collisions at sqrt(sNN) = 130GeVJun 20 2003We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from Au+Au collisions at sqrt(sNN) = 130GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum ... More

Strange anti-particle to particle ratios at mid-rapidity in sqrt(s_NN)= 130 GeV Au+Au CollisionsNov 22 2002Jul 15 2003Values of the ratios in the mid-rapidity yields of anti-Lambda/Lambda = 0.71 +/- 0.01(stat.) +/- 0.04(sys.), anti-Xi+/Xi- = 0.83 +/- 0.04(stat.) +/- 0.05 (sys.), anti-Omega+/Omega- = 0.95 +/- 0.15(stat) +/- 0.05(sys.) and K+/K- 1.092 +/- 0.023(combined) ... More

Search for the decay K_L-> pi^0 nu nubarJun 08 1998Jun 10 1998We report on a search for the rare decay K_L -> pi^0 nu nubar in the KTeV experiment at Fermilab. We searched for two-photon events whose kinematics were consistent with an isolated pi^0 coming from the decay K_L -> pi^0 nu nubar. One candidate event ... More

Multiplicity fluctuations in Au+Au collisions at $\sqrt{s_{NN}}=130$ GeVJul 08 2003We present the results of charged particle fluctuations measurements in Au + Au collisions at $\sqrt{s_{NN}}=130$ GeV using the STAR detector. Dynamical fluctuations measurements are presented for inclusive charged particle multiplicities as well as for ... More

Evidence for the Galactic X-ray Bulge IIJul 10 1998A mosaic of 5 \ros~PSPC pointed observations in the Galactic plane ($l\sim25^{\circ}$) reveals X-ray shadows in the $0.5-2.0$ keV band cast by distant molecular clouds. The observed on-cloud and off-cloud X-ray fluxes indicate that $\sim15$% and $\sim37$% ... More

The TeV Energy Spectrum of Mrk 421 Measured in A High Flaring StateAug 28 2007The BL Lac object (blazar) Mrk 421 was observed during its outburst in April 2004 with the Whipple 10 m telescope for a total of about 24.5 hours. The measured gamma-ray rate varied substantially over the range from 4 to 10 gamma's/min and eventually ... More

X-Ray Spectral Variability of Extreme BL Lac AGN H1426+428Oct 08 2003Between 7 March 2002 and 15 June 2002, intensive X-ray observations were carried out on the extreme BL Lac object H1426+428 with instruments on board the Rossi X-ray Timing Explorer (RXTE). These instruments provide measurements of H1426+428 in the crucial ... More

The Spectra and Classification of L and T DwarfsSep 24 2001In this contribution, I discuss some of the salient features of L and T dwarf spectra in both the red optical (6300--10000 {\AA}) and near-infrared (1--2.5 $\micron$) wavelength regimes. Important absorption bands and lines, including those of H$_2$O, ... More

Minor arcs, mean values, and restriction theory for exponential sums over smooth numbersAug 07 2014We investigate exponential sums over those numbers $\leq x$ all of whose prime factors are $\leq y$. We prove fairly good minor arc estimates, valid whenever $\log^{3}x \leq y \leq x^{1/3}$. Then we prove sharp upper bounds for the $p$-th moment of (possibly ... More

A note on the maximum of the Riemann zeta function, and log-correlated random variablesApr 02 2013In recent work, Fyodorov and Keating conjectured the maximum size of $|\zeta(1/2+it)|$ in a typical interval of length O(1) on the critical line. They did this by modelling the zeta function by the characteristic polynomial of a random matrix; relating ... More

Deformation of the CP(1) model leading to fixed size solitons in 2+1 dimensionsMar 04 2013Sep 20 2013We discuss static particle-like solitons in the 2+1 dimensional CP(1) model with a small mass deformation $m$ preserving a $U(1) \times Z_2$ symmetry in the Lagrangian. Due to the breaking of scale invariance, the energy function becomes a strictly increasing ... More

Delta- phi Delta- eta Correlations in Central Au+Au Collisions at sqrt{s_{NN}} = 200 GevJul 07 2006Jan 24 2007We report charged-particle pair correlation analyses in the space of Delta -phi (azimuth) and Delta -eta (pseudo-rapidity), for central Au + Au collisions at sqrt{s_{NN}} = 200 GeV in the STAR detector. The analysis involves unlike-sign charge pairs and ... More

Proton-lambda correlations in central Au+Au collisions at sqrt (s_NN)=200 GeVNov 01 2005Dec 09 2006We report on p-Lambda, p-Lambda bar, p bar-Lambda and p bar-Lambda bar correlation functions constructed in central Au-Au collisions at sqrt(s_NN)=200GeV by the STAR experiment at RHIC. The proton and lambda source size is inferred from the p-Lambda and ... More

Multi-strange baryon elliptic flow in Au+Au collisions at sqrt(s_NN)= 200 GeVApr 22 2005We report on the first measurement of elliptic flow $v_2(p_T)$ of multi-strange baryons $\Xi+\bar{Xi}$ and $\Omega+\bar{Omega} in heavy-ion collisions. In minimum bias Au+Au collisions at sqrt(s_NN) = 200 GeV, a significant amount of elliptic flow, comparable ... More

Two-particle correlations on transverse momentum and momentum dissipation in Au-Au collisions at $\sqrt{s_{NN}}$ = 130 GeVAug 11 2004Jan 12 2007Measurements of two-particle correlations on transverse momentum $p_t$ for Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV are presented. Significant large-momentum-scale correlations are observed for charged primary hadrons with $0.15 \leq p_t \leq 2$ ... More

Identified particle distributions in pp and Au+Au collisions at sqrt{s_NN}=200 GeVOct 06 2003Transverse mass and rapidity distributions for charged pions, charged kaons, protons and antiprotons are reported for sqrt{s_NN}=200 GeV pp and Au+Au collisions at RHIC. The transverse mass distributions are rapidity independent within |y|<0.5, consistent ... More

An "almost" full embedding of the category of graphs into the category of groupsDec 02 2009May 18 2010We construct a functor from the category of graphs to the category of groups which is faithful and "almost" full, in the sense that it induces bijections of the Hom sets up to trivial homomorphisms and conjugation in the category of groups. We provide ... More

Large localizations of finite groupsOct 09 2008We construct examples of localizations in the category of groups which take the Mathieu group $M_{11}$ to groups of arbitrarily large cardinality which are ``abelian up to finitely many generators''. The paper is part of a broader study on the group theoretic ... More

SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf BinaryJun 13 2007SDSS J080531.84+481233.0 is a peculiar L-type dwarf that exhibits unusually blue near-infrared and mid-infrared colors and divergent optical (L4) and near-infrared (L9.5) spectral classifications. These peculiar spectral traits have been variously attributed ... More

The Spectrum of HD 3651B: An Extrasolar Nemesis?Sep 20 2006Nov 16 2006This article has been withdrawn; see astro-ph/0611542

Binaries and the L Dwarf/T Dwarf TransitionNov 15 2006High-resolution imaging has revealed an unusually high binary fraction amongst objects spanning the transition between the L dwarf and T dwarf spectral classes. In an attempt to reproduce and unravel the origins of this apparent binary excess, I present ... More

Every countable group is the fundamental group of some compact subspace of R^4Nov 10 2014Feb 16 2015For every countable group G we construct a compact path connected subspace K of R^4 whose fundamental group is isomorphic to G. Our construction is much simpler than the one found recently by Virk.

Directed flow in Au+Au collisions at $\sqrt{s_{_{NN}}}$ =62.4 GeVOct 17 2005Jan 18 2006We present the directed flow ($v_1$) measured in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 62.4 GeV in the mid-pseudorapidity region $|\eta|<1.3$ and in the forward pseudorapidity region $2.5 < |\eta| < 4.0$. The results are obtained using the three-particle ... More

Minijet deformation and charge-independent angular correlations on momentum subspace $(η,φ)$ in Au-Au collisions at $\sqrt{s_{NN}}$ = 130 GeVNov 04 2004Nov 01 2005First measurements of charge-independent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) are presented for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ ... More

Hadronization geometry from net-charge angular correlations on momentum subspace ($η,φ$) in Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeVJun 30 2004Nov 19 2005We present the first measurements of charge-dependent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and ... More

Cross Sections and Transverse Single-Spin Asymmetries in Forward Neutral-Pion Production from Proton Collisions at \sqrt{s} = 200 GeVOct 29 2003Apr 29 2004Measurements of the production of forward high-energy pi0 mesons from transversely polarized proton collisions at \sqrt{s}=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing ... More

Azimuthal anisotropy at RHIC: the first and fourth harmonicsOct 28 2003Jan 22 2004We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). ... More

Applications of Cosmological Perturbation TheoryJun 02 2011Cosmological perturbation theory is crucial for our understanding of the universe. The linear theory has been well understood for some time, however developing and applying the theory beyond linear order is currently at the forefront of research in theoretical ... More

Fruitbat: A Python Package for Estimating Redshifts of Fast Radio BurstsMay 10 2019Fruitbat is an open source Python 2/3 package for estimating redshifts, energies and the galactic dispersion measure contributions of fast radio bursts (FRBs). Fruitbat combines various dispersion measure (DM) and redshift relations with the YMW16 galactic ... More

Equations for Complex-Valued, Twisting, Type N, Vacuum Solutions, with one or two Killing/homothetic vectorsAug 23 2001HH-spaces, i.e., complex spacetimes, of Petrov type NxN are determined by a trio of pde's for two functions, lambda and a, of three independent variables (and also two gauge functions, chosen to be two of the independent variables if one prefers). As ... More

Independent dynamic acousto-mechanical and electrostatic control of individual quantum dots in a LiNbO$_{3}$-GaAs hybridOct 22 2014Dec 16 2014We demonstrate tuning of single quantum dot emission lines by the combined action of the dynamic acoustic field of a radio frequency surface acoustic wave and a static electric field. Both tuning parameters are set all-electrically in a LiNbO$_{3}$-GaAs ... More

Ultracool Subdwarfs: Subsolar Metallicity Objects Down to Substellar MassesJan 29 2007In the past few years, astronomers have uncovered several very low-temperature, metal-poor stars with halo or thick disk kinematics and peculiar spectral and photometric properties, so-called ultracool subdwarfs. These include the first examples of L ... More

The Brown Dwarf-Exoplanet ConnectionMar 09 2009Brown dwarfs are commonly regarded as easily-observed templates for exoplanet studies, with comparable masses, physical sizes and atmospheric properties. There is indeed considerable overlap in the photospheric temperatures of the coldest brown dwarfs ... More

Clouds, Brightening and Multiplicity Across the L Dwarf/T Dwarf TransitionOct 03 2008The transition between the two lowest-luminosity spectral classes of brown dwarfs--the L dwarfs and T dwarfs--is traversed by nearly all brown dwarfs as they cool over time. Yet distinct features of this transition, such as the "J-band bump" and an unusually ... More

Pickands' constant $H_α$ does not equal $1/Γ(1/α)$, for small $α$Apr 22 2014Pickands' constants $H_{\alpha}$ appear in various classical limit results about tail probabilities of suprema of Gaussian processes. It is an often quoted conjecture that perhaps $H_{\alpha} = 1/\Gamma(1/\alpha)$ for all $0 < \alpha \leq 2$, but it is ... More

Sharp conditional bounds for moments of the Riemann zeta functionMay 20 2013We prove, assuming the Riemann Hypothesis, that \int_{T}^{2T} |\zeta(1/2+it)|^{2k} dt \ll_{k} T log^{k^{2}} T for any fixed k \geq 0 and all large T. This is sharp up to the value of the implicit constant. Our proof builds on well known work of Soundararajan, ... More

Bombieri--Vinogradov and Barban--Davenport--Halberstam type theorems for smooth numbersAug 29 2012We prove Bombieri--Vinogradov and Barban--Davenport--Halberstam type theorems for the y-smooth numbers less than x, on the range log^{K}x \leq y \leq x. This improves on the range \exp{log^{2/3 + \epsilon}x} \leq y \leq x that was previously available. ... More

Chains of group localizationsDec 03 2009We construct long sequences of localization functors L_a in the category of abelian groups such that L_a > L_b for infinite cardinals a < b less than some k. For sufficiently large free abelian groups F and a < b we have proper inclusions of L_aF into ... More

K(892)* Resonance Production in Au+Au and p+p Collisions at sqrt(sNN) = 200 GeV at RHICDec 09 2004Apr 22 2005The short-lived $K(892)^{*}$ resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of $K^{*}$ in $\sqrt{s_{_{NN}}}$ = 200 GeV Au+Au and $p+p$ collisions ... More

Open charm yields in d+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeVJul 06 2004Jan 07 2005Mid-rapidity open charm spectra from direct reconstruction of $D^{0}$($\bar{D^0}$)$\to K^{\mp}\pi^{\pm}$ in d+Au collisions and indirect electron/positron measurements via charm semileptonic decays in p+p and d+Au collisions at \srt = 200 GeV are reported. ... More

Forward Neutral Pion Production in p+p and d+Au Collisions at sqrt(s_NN)=200 GeVFeb 09 2006Oct 12 2006Measurements of the production of forward pi0 mesons from p+p and d+Au collisions at sqrt(s_NN)=200 GeV are reported. The p+p yield generally agrees with next-to-leading order perturbative QCD calculations. The d+Au yield per binary collision is suppressed ... More

Homotopical localizations at a spaceMay 17 2002Our main motivation for the work presented in this paper is to construct a localization functor, in a certain sense dual to the f-localization of Bousfield and Farjoun, and to study some of its properties. We succeed in a case which is related to the ... More

An almost full embedding of the category of graphs into the category of abelian groupsApr 29 2011Mar 19 2014We construct an embedding G of the category of graphs into the category of abelian groups such that for graphs X and Y we have Hom(GX,GY)=Z[Hom(X,Y)], the free abelian group whose basis is the set Hom(X,Y). The isomorphism is functorial in X and Y. The ... More

Cloud Formation and Dynamics in Cool Dwarf and Hot Exoplanetary AtmospheresOct 12 2009The lowest-mass stars, brown dwarfs and extrasolar planets present challenges and opportunities for understanding dynamics and cloud formation processes in low-temperature atmospheres. For brown dwarfs, the formation, variation and rapid depletion of ... More

The SpeX Prism Library: 1000+ Low-resolution, Near-infrared Spectra of Ultracool M, L, T and Y DwarfsJun 18 2014The SpeX Prism Library (SPL) is a uniform compilation of low-resolution (R ~ 75-120), near-infrared (0.8-2.5 micron) spectra spanning a decade of observations with the IRTF SpeX spectrograph. Primarily containing ultracool M, L, T and Y dwarfs, this spectral ... More

The L dwarf/T dwarf transition: multiplicity, magnetic activity and mineral meteorology across the hydrogen burning limitDec 31 2012The transition between the L dwarf and T dwarf spectral classes is one of the most remarkable along the stellar/brown dwarf Main Sequence, separating sources with photospheres containing mineral condensate clouds from those containing methane and ammonia ... More

The Physical Properties of HD 3651B: An Extrasolar Nemesis?Nov 16 2006I present detailed analysis of the near infrared spectrum of HD 3651B, a faint, co-moving wide companion to the nearby planet-hosting star HD 3651. These data confirm the companion as a brown dwarf with spectral type T8, consistent with the analysis of ... More

Applying Artifical Neural Networks To Predict Nominal Vehicle PerformanceMar 16 2016This paper investigates the use of artificial neural networks (ANNs) to replace traditional algorithms and manual review for identifying anomalies in vehicle run data. The specific data used for this study is from undersea vehicle qualification tests. ... More

Modelling the transmission dynamics of online social contagionJan 31 2016During 2014-15, there were several outbreaks of nominated-based online social contagion. These infections, which were transmitted from one individual to another via posts on social media, included games such as 'neknomination', 'ice bucket challenge', ... More

Neutral strange particle production at mid unit rapidity in p+p collisions at sqrt(s) = 200 GeVMar 12 2004Mar 19 2004We briefly discuss the methods of analysing reconstructed neutral strange particles in p+p collision data measured at sqrt(s) = 200 GeV taken using the Solenoidal Tracker At RHIC (STAR) detector. We present spectra for K0 short, lambda and anti-lambda ... More

Transverse-momentum $p_t$ correlations on $(η,φ)$ from mean-$p_{t}$ fluctuations in Au-Au collisions at $\sqrt{s_{NN}} = $ 200 GeVSep 23 2005Apr 11 2006We present first measurements of the pseudorapidity and azimuth $(\eta,\phi)$ bin-size dependence of event-wise mean transverse momentum $<p_{t} >$ fluctuations for Au-Au collisions at $\sqrt{s_{NN}} = 200$ GeV. We invert that dependence to obtain $p_t$ ... More

Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC CollisionsJan 13 2005Apr 26 2005We review the most important experimental results from the first three years of nucleus-nucleus collision studies at RHIC, with emphasis on results from the STAR experiment, and we assess their interpretation and comparison to theory. The theory-experiment ... More

Stable laws and Beurling kernelsJun 14 2016We identify a close relation between stable distributions and the limiting homomorphisms central to the theory of regular variation. In so doing some simplifications are achieved in the direct analysis of these laws in Pitman and Pitman (2016); stable ... More

The future of cosmology and the role of non-linear perturbationsNov 29 2011Jan 18 2012Cosmological perturbation theory is a key tool to study the universe. The linear or first order theory is well understood, however, developing and applying the theory beyond linear order is at the cutting edge of current research in theoretical cosmology. ... More

Gauge conditions in combined dark energy and dark matter systemsAug 04 2010Oct 12 2010When analysing a system consisting of both dark matter and dark energy, an often used practice in the literature is to neglect the perturbations in the dark energy component. However, it has recently been argued, through the use of numerical simulations, ... More

Relating metric and covariant perturbation theories in $f(R)$ gravityApr 13 2016Modified theories of gravity have been invoked recently as an alternative to dark energy, in an attempt to explain the apparent accelerated expansion of the universe at the present time. In order to describe inhomogeneities in cosmological models, cosmological ... More

The generalized Levinger transformationDec 22 2007In this paper, we present new results relating the numerical range of a matrix $A$ with generalized Levinger transformation $\mathcal{L}(A,\alpha,\beta) = \alphaH_A +\betaS_A$, where $H_A$ and $S_A$, are respectively the Hermitian and skew-hermitian parts ... More

The Riemann zeta function in short intervals [after Najnudel, and Arguin, Belius, Bourgade, Radziwiłł, and Soundararajan]Apr 17 2019This is the text to accompany my Bourbaki seminar from 30th March 2019, on the maximum size of the Riemann zeta function in "almost all" intervals of length 1 on the critical line. It surveys the conjecture of Fyodorov--Hiary--Keating on the behaviour ... More

Brown Dwarfs as Galactic ChronometersNov 15 2008Brown dwarfs are natural clocks, cooling and dimming over time due to insufficient core fusion. They are also numerous and present in nearly all Galactic environments, making them potentially useful chronometers for a variety of Galactic studies. For ... More

Scaling Properties of Hyperon Production in Au+Au Collisions at sqrt(s_NN) = 200 GeVJun 07 2006We present the scaling properties of Lambda, Xi, Omega and their anti-particles produced at mid-rapidity in Au+Au collisions at RHIC at sqrt(s_NN) = 200 GeV. The yield of multi-strange baryons per participant nucleon increases from peripheral to central ... More

Direct observation of dijets in central Au+Au collisions at sqrt(s_NN) = 200 GeVApr 26 2006The STAR Collaboration at RHIC reports measurements of azimuthal correlations of high transverse momentum (p_T) charged hadrons in Au+Au collisions at higher p_T than reported previously. As p_T is increased, a narrow, back-to-back peak emerges above ... More

Measurements of transverse energy distributions in Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeVJul 02 2004Transverse energy ($E_T$) distributions have been measured for Au+Au collisions at $\sqrt{s_{NN}}= 200$ GeV by the STAR collaboration at RHIC. $E_T$ is constructed from its hadronic and electromagnetic components, which have been measured separately. ... More

Event-wise mean p_t fluctuations in Au-Au collisions at sqrt{s_{NN}} = 130 GeVAug 29 2003Apr 26 2005We present the first large-acceptance measurement of event-wise mean transverse momentum mean p_t fluctuations for Au-Au collisions at nucleon-nucleon center-of-momentum collision energy sqrt{s_{NN}} = 130 GeV. The observed non-statistical mean p_t fluctuations ... More

Cosmological Perturbations: Vorticity, Isocurvature and Magnetic FieldsSep 16 2014In this paper I review some recent, interlinked, work undertaken using cosmological perturbation theory -- a powerful technique for modelling inhomogeneities in the Universe. The common theme which underpins these pieces of work is the presence of non-adiabatic ... More

Homomorphisms from Functional Equations: The Goldie EquationJul 15 2014Nov 07 2014The theory of regular variation, in its Karamata and Bojani\'c-Karamata/de Haan forms, is long established and makes essential use of the Cauchy functional equation. Both forms are subsumed within the recent theory of Beurling regular variation, developed ... More

Cavity versus dot emission in strongly coupled quantum dots-cavity systemsFeb 18 2011We discuss the spectral lineshapes of N quantum dots in strong coupling with the single mode of a microcavity. Nontrivial features are brought by detuning the emitters or probing the direct exciton emission spectrum. We describe dark states, quantum nonlinearities, ... More

Linear and Non-linear Response of Lithographically Defined Plasmonic NanoantennasFeb 18 2015Feb 20 2015We present numerical studies, nano-fabrication and optical characterization of bowtie nanoantennas demonstrating their superior performance with respect to the electric field enhancement as compared to other Au nanoparticle shapes. For optimized parameters, ... More

Estimating magnetic filling factors from Zeeman-Doppler magnetogramsMar 13 2019Low-mass stars are known to have magnetic fields that are believed to be of dynamo origin. Two complementary techniques are principally used to characterise them. Zeeman-Doppler imaging (ZDI) can determine the geometry of the large-scale magnetic field ... More

Direct measurement of plasmon propagation lengths on lithographically defined metallic waveguides on GaAsOct 19 2011We present optical investigations of rectangular surface plasmon polariton waveguides lithographically defined on GaAs substrates. The plasmon propagation length is directly determined using a confocal microscope, with independent polarization control ... More

The Effect of Combined Magnetic Geometries on Thermally Driven Winds II: Dipolar, Quadrupolar and Octupolar TopologiesJan 23 2018During the lifetime of sun-like or low mass stars a significant amount of angular momentum is removed through magnetised stellar winds. This process is often assumed to be governed by the dipolar component of the magnetic field. However, observed magnetic ... More

Electrically probing photonic bandgap phenomena in contacted defect nanocavitiesSep 13 2007We demonstrate an electrically tunable two dimensional photonic crystal nanocavity containing InAs self assembled quantum dots. Photoluminescence and electroluminescence measurements are combined to probe the cavity mode structure and demonstrate a local ... More

Manipulation of the Spontaneous Emission Dynamics of Quantum Dots in 2D Photonic CrystalsJan 04 2005Apr 08 2005We demonstrate the ability to control the spontaneous emission dynamics of self-assembled quantum dots via the local density of optical modes in 2D-photonic crystals. We show that an incomplete 2D photonic bandgap is sufficient to significantly lengthen ... More

Coplanar stripline antenna design for optically detected magnetic resonance on semiconductor quantum dotsFeb 14 2011We report on the development and testing of a coplanar stripline antenna that is designed for integration in a magneto-photoluminescence experiment to allow coherent control of individual electron spins confined in single self-assembled semiconductor ... More

Selective Optical Charge Generation, Storage and Readout in a Single Self Assembled Quantum DotDec 16 2008Jan 20 2009We report the investigation of a single quantum dot charge storage device. The device allows selective optical charging of a single dot with electrons, storage of these charges over timescales much longer than microseconds and reliable optical readout ... More

Temporal Monitoring of Non-resonant Feeding of Semiconductor Nanocavity Modes by Quantum Dot Multiexciton TransitionsMar 15 2010We experimentally investigate the non-resonant feeding of photons into the optical mode of a zero dimensional nanocavity by quantum dot multiexciton transitions. Power dependent photoluminescence measurements reveal a super-linear power dependence of ... More

Cavity-resonant excitation for efficient single photon generationMar 17 2008We present an efficiently pumped single photon source based on single quantum dots (QD) embedded in photonic crystal nanocavities. Resonant excitation of a QD via a higher order cavity mode results in a 100$\times$ reduced optical power at the saturation ... More

Efficient Spatial Redistribution of Quantum Dot Spontaneous Emission from 2D Photonic CrystalsJun 05 2007We investigate the modification of the spontaneous emission dynamics and external quantum efficiency for self-assembled InGaAs quantum dots coupled to extended and localised photonic states in GaAs 2D-photonic crystals. The 2D-photonic bandgap is shown ... More

Surface acoustic wave regulated single photon emission from a coupled quantum dot-nanocavity systemMay 16 2016Jul 11 2016A coupled quantum dot--nanocavity system in the weak coupling regime of cavity quantumelectrodynamics is dynamically tuned in and out of resonance by the coherent elastic field of a $f_{\rm SAW}\simeq800\,\mathrm{MHz}$ surface acoustic wave. When the ... More

Proper Motion of Pulsar B1800-21Jul 20 2006Oct 20 2006We report high angular resolution, multi-epoch radio observations of the young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning approximately a ten year period, we calculate the proper motion of the pulsar. We obtain a proper motion ... More

The Spectra of T Dwarfs. II. Red Optical DataMay 08 2003We present 6300--10100 {\AA} spectra for a sample of 13 T dwarfs observed using LRIS mounted on the Keck I 10m Telescope. A variety of features are identified and analyzed, including pressure-broadened K I and Na I doublets; narrow Cs I and Rb I lines; ... More

CriPS: Critical Dynamics in Particle Swarm OptimizationFeb 27 2014Particle Swarm Optimisation (PSO) makes use of a dynamical system for solving a search task. Instead of adding search biases in order to improve performance in certain problems, we aim to remove algorithm-induced scales by controlling the swarm with a ... More

A graphical tool for demonstrating the techniques of radio interferometryNov 01 2012We present a graphical interface designed to demonstrate the techniques of radio interferometry used by telescopes like ALMA, e-Merlin, the JVLA and SKA, in a manner accessible to the general public. Interferometry is an observational tech- nique used ... More

Study of the volume and spin collapse in orthoferrite LuFeO_3 using LDA+UApr 29 2009Rare earth (R) orthoferrites RFeO_3 exhibit large volume transitions associated with a spin collapse. We present here ab initio calculations on LuFeO_3. We show that taking into account the strong correlation among the Fe-3d electrons is necessary. Indeed, ... More

Low energy dynamics of gapless and quasi-gapless modes of vortices in superfluid $^3$He-BSep 19 2013Oct 09 2013We discuss the low energy effective dynamics of gapless excitations of the mass vortices of systems similar to the Ginzburg-Landau description of superfluid helium-3 in the bulk B phase. Our approach is to determine the vortex solution by considering ... More

An algebraic construction of twin-like modelsSep 19 2011Oct 04 2011If the generalized dynamics of K field theories (i.e., field theories with a non-standard kinetic term) is taken into account, then the possibility of so-called twin-like models opens up, that is, of different field theories which share the same topological ... More

Ab initio thermodynamic model of Cu$_2$ZnSnS$_4$Mar 31 2014Thin-film solar cells based on the semiconductor Cu$_2$ZnSnS$_4$ (CZTS) are a promising candidate for Terawatt-scale renewable energy generation. While CZTS is composed of earth abundant and non-toxic elements, arranged in the kesterite crystal structure, ... More