Results for "Sarah T. Stewart"

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The structure of terrestrial bodies: Impact heating, corotation limits and synestiasMay 22 2017During accretion, terrestrial bodies attain a wide range of thermal and rotational states, which are accompanied by significant changes in physical structure (size, shape, pressure and temperature profile, etc.). However, variations in structure have ... More
Collisions Between Gravity-Dominated Bodies: 1. Outcome Regimes and Scaling LawsJun 29 2011Jan 05 2012Collisions are the core agent of planet formation. In this work, we derive an analytic description of the dynamical outcome for any collision between gravity-dominated bodies. We conduct high-resolution simulations of collisions between planetesimals; ... More
Erosive Hit-and-Run Impact Events: Debris UnboundNov 16 2015Oct 31 2016Erosive collisions among planetary embryos in the inner solar system can lead to multiple remnant bodies, varied in mass, composition and residual velocity. Some of the smaller, unbound debris may become available to seed the main asteroid belt. The makeup ... More
Bayesian hypothesis tests with diffuse priors: Can we have our cake and eat it too?Oct 25 2017We introduce a new class of priors for Bayesian hypothesis testing, which we name "cake priors". These priors circumvent Bartlett's paradox (also called the Jeffreys-Lindley paradox); the problem associated with the use of diffuse priors leading to nonsensical ... More
The Formation of the Collisional Family around the Dwarf Planet HaumeaMar 30 2010Haumea, a rapidly rotating elongated dwarf planet (~ 1500 km in diameter), has two satellites and is associated with a "family" of several smaller Kuiper Belt objects (KBOs) in similar orbits. All members of the Haumea system share a water ice spectral ... More
Minimum Radii of Super-Earths: Constraints from Giant ImpactsMar 01 2010The detailed interior structure models of super-Earth planets show that there is degeneracy in the possible bulk compositions of a super-Earth at a given mass and radius, determined via radial velocity and transit measurements, respectively. In addition, ... More
Constraints on the Source of Lunar Cataclysm ImpactorsDec 10 2009Multiple impact basins formed on the Moon about 3.8 Gyr ago in what is known as the lunar cataclysm or late heavy bombardment. Many workers currently interpret the lunar cataclysm as an impact spike primarily caused by main-belt asteroids destabilized ... More
The origin of the Moon within a terrestrial synestiaFeb 28 2018The giant impact hypothesis remains the leading theory for lunar origin. However, current models struggle to explain the Moon's composition and isotopic similarity with Earth. Here we present a new lunar origin model. High-energy, high-angular momentum ... More
Variational Discriminant Analysis with Variable SelectionDec 17 2018Feb 17 2019A Bayesian method that seamlessly fuses classification via discriminant analysis and hypothesis testing is developed. Building upon the original discriminant analysis classifier, modelling components are added to identify discriminative variables. A combination ... More
HOList: An Environment for Machine Learning of Higher-Order Theorem Proving (extended version)Apr 05 2019We present an environment, benchmark, and deep learning driven automated theorem prover for higher-order logic. Higher-order interactive theorem provers enable the formalization of arbitrary mathematical theories and thereby present an interesting, open-ended ... More
Attention but not musical training affects auditory streamingAug 11 2017While musicians generally perform better than non-musicians in various auditory discrimination tasks, effects of specific instrumental training have received little attention. The effects of instrument-specific musical training on auditory grouping in ... More
Using photoemission spectroscopy to probe a strongly interacting Fermi gasApr 30 2008Ultracold atom gases provide model systems in which many-body quantum physics phenomena can be studied. Recent experiments on Fermi gases have realized a phase transition to a Fermi superfluid state with strong interparticle interactions. This system ... More
Exponential-Family Models of Random Graphs: Inference in Finite-, Super-, and Infinite Population ScenariosJul 15 2017Mar 29 2019Exponential-family Random Graph Models (ERGMs) constitute a large statistical framework for modeling sparse and dense random graphs, short- and long-tailed degree distributions, covariates, and a wide range of complex dependencies. Special cases of ERGMs ... More
Exponential-Family Models of Random Graphs: Inference in Finite-, Super-, and Infinite Population ScenariosJul 15 2017Nov 06 2018Exponential-family Random Graph Models (ERGMs) constitute a large statistical framework for modeling sparse and dense random graphs, short- and long-tailed degree distributions, covariates, and a wide range of complex dependencies. Special cases of ERGMs ... More
Full Numerical Simulations of Catastrophic Small Body CollisionsNov 02 2008The outcome of collisions between small icy bodies, such as Kuiper belt objects, is poorly understood and yet a critical component of the evolution of the trans-Neptunian region. The expected physical properties of outer solar system materials (high porosity, ... More
The Elusive Origin of MercuryDec 21 2017The MESSENGER mission sought to discover what physical processes determined Mercury's high metal to silicate ratio. Instead, the mission has discovered multiple anomalous characteristics about our innermost planet. The lack of FeO and the reduced oxidation ... More
Direct observation of the Fermi surface in an ultracold atomic gasMar 30 2012The ideal (i.e. noninteracting), homogeneous Fermi gas, with its characteristic sharp Fermi surface in the momentum distribution, is a fundamental concept relevant to the behavior of many systems. With trapped Fermi gases of ultracold atoms, one can realize ... More
Verification of universal relations in a strongly interacting Fermi gasFeb 09 2010Many-body fermion systems are important in many branches of physics, including condensed matter, nuclear, and now cold atom physics. In many cases, the interactions between fermions can be approximated by a contact interaction. A recent theoretical advance ... More
A Double Parametric Bootstrap Test for Topic ModelsNov 19 2017Nov 21 2017Non-negative matrix factorization (NMF) is a technique for finding latent representations of data. The method has been applied to corpora to construct topic models. However, NMF has likelihood assumptions which are often violated by real document corpora. ... More
Formation of bright matter-wave solitons during the collapse of Bose-Einstein condensatesJan 30 2006We observe bright matter-wave solitons form during the collapse of 85Rb condensates in a three-dimensional magnetic trap. The collapse is induced by using a Feshbach resonance to suddenly switch the atomic interactions from repulsive to attractive. Remnant ... More
On the postcritical set of a rational mapSep 20 2017The postcritical set $P(f)$ of a rational map $f:\mathbb P^1\to \mathbb P^1$ is the smallest forward invariant subset of $\mathbb P^1$ that contains the critical values of $f$. In this paper we show that every finite set $X\subset \mathbb P^1(\overline{\mathbb ... More
3D SPH simulations of grain growth in protoplanetary disksDec 05 2007Jan 10 2008We present the first results of the treatment of grain growth in our 3D, two-fluid (gas+dust) SPH code describing protoplanetary disks. We implement a scheme able to reproduce the variation of grain sizes caused by a variety of physical processes and ... More
Erosive Hit-and-Run Impact Events: Debris UnboundNov 16 2015Erosive collisions among planetary embryos in the inner solar system can lead to multiple remnant bodies, varied in mass, composition and residual velocity. Some of the smaller, unbound debris may become available to seed the main asteroid belt. The makeup ... More
Self-induced dust traps: overcoming planet formation barriersJan 04 2017Aug 31 2017Planet formation is thought to occur in discs around young stars by the aggregation of small dust grains into much larger objects. The growth from grains to pebbles and from planetesimals to planets is now fairly well understood. The intermediate stage ... More
On the maximum grain size entrained by photoevaporative windsAug 29 2016We model the behaviour of dust grains entrained by photoevaporation-driven winds from protoplanetary discs assuming a non-rotating, plane-parallel disc. We obtain an analytic expression for the maximum entrainable grain size in extreme-UV radiation-driven ... More
Algorithmic Diversity for Software SecurityDec 13 2013Software diversity protects against a modern-day exploits such as code-reuse attacks. When an attacker designs a code-reuse attack on an example executable, it relies on replicating the target environment. With software diversity, the attacker cannot ... More
Collisional Stripping and Disruption of Super-EarthsJul 02 2009The final stage of planet formation is dominated by collisions between planetary embryos. The dynamics of this stage determine the orbital configuration and the mass and composition of planets in the system. In the solar system, late giant impacts have ... More
Physical effects of collisions in the Kuiper beltMay 27 2007Collisions are a major modification process over the history of the Kuiper Belt. Recent work illuminates the complex array of possible outcomes of individual collisions onto porous, volatile bodies. The cumulative effects of such collisions on the surface ... More
Water/Icy Super-Earths: Giant Impacts and Maximum Water ContentJul 19 2010Water-rich super-Earth exoplanets are expected to be common. We explore the effect of late giant impacts on the final bulk abundance of water in such planets. We present the results from smoothed particle hydrodynamics simulations of impacts between differentiated ... More
Event activity measurements and mid-rapidity correlations in 200 GeV p+Au collisions at STARJan 10 2019These proceedings report preliminary measurements of correlations between mid-rapidity charged tracks and high-rapidity event activity (EA) at STAR for $\sqrt{s_\mathrm{NN}}= 200\, \mathrm{GeV}$ p+Au collisions taken in 2015. These correlations are intriguing ... More
Lectures on the stable homotopy of BGOct 31 2007Mar 30 2009This paper is a survey of the stable homotopy theory of BG for G a finite group. It is based on a series of lectures given at the Summer School associated with the Topology Conference at the Vietnam National University, Hanoi, August 2004.
p-wave Feshbach moleculesMar 03 2007May 01 2008We have produced and detected molecules using a p-wave Feshbach resonance between 40K atoms. We have measured the binding energy and lifetime for these molecules and we find that the binding energy scales approximately linearly with magnetic field near ... More
Thermal Inflation and the Gravitational Wave BackgroundJan 28 2008Apr 29 2008We consider the impact of thermal inflation -- a short, secondary period of inflation that can arise in supersymmetric scenarios -- on the stochastic gravitational wave background. We show that while the primordial inflationary gravitational wave background ... More
Parity-Time Symmetry in Coherently Coupled Vertical Cavity Laser ArraysOct 05 2016Dec 13 2016We report parity-time (PT) symmetry breaking in electrically injected, coherently coupled, vertical cavity surface emitting laser arrays. We predict beam steering, mode evolution and mode hopping as a consequence of the non-Hermiticity of the array analyzed ... More
Neutron scattering and muSR investigations of the spin liquid state with quenched disorder in LuCuGaO4Feb 04 2010May 28 2013LuCuGaO4 has magnetic Cu2+ and diamagnetic Ga3+ ions distributed on a triangular bilayer and is suggested to undergo a spin-glass transition with T_g approximately 0.4 K. Using muSR and neutron scattering measurements, we show that at low temperature ... More
Probing Pair-Correlated Fermionic Atoms through Correlations in Atom Shot NoiseFeb 17 2005Pair-correlated fermionic atoms are created through dissociation of weakly bound molecules near a magnetic-field Feshbach resonance. We show that correlations between atoms in different spin states can be detected using the atom shot noise in absorption ... More
MOSAIK: A hash-based algorithm for accurate next-generation sequencing read mappingSep 04 2013This paper presents an accurate short-read mapper for next-generation sequencing data which is widely used in the 1000 Genomes Project, and human clinical and other species genome studies.
Relationship between resistivity and specific heat in a canonical non-magnetic heavy fermion alloy system: UPt_5-xAu_xOct 27 1998UPt_(5-x)Au_x alloys form in a single crystal structure, cubic AuBe_5-type, over a wide range of concentrations from x = 0 to at least x = 2.5. All investigated alloys, with an exception for x = 2.5, were non-magnetic. Their electronic specific heat coefficient ... More
Thermal evolution of Pt-rich FePt/Fe3O4 heterodimers studied using x-ray absorption near edge spectroscopyFeb 25 2011FePt/Fe3O4 nanoparticles can be used as building blocks to obtain, upon thermal annealing, magnetic nanocomposites with combined magnetic properties. Although the pre- and post-annealed samples are usually well characterized, a detailed investigation ... More
ASCA observations of deep ROSAT fields V. The X-ray spectrum of hard X-ray selected QSOsMay 08 2001We present an analysis of the \rosat and \asca spectra of 21 broad line AGN (QSOs) with $z\sim 1$ detected in the 2-10 keV band with the \asca \gis. The summed spectrum in the \asca band is well described by a power-law with $\Gamma=1.56\pm0.18$, flatter ... More
The discovery of a high redshift type 2 QSOSep 04 1995We report the discovery of a high redshift, narrow emission-line galaxy identified in the optical follow-up of deep ROSAT fields. The object has a redshift of z=2.35 and its narrow emission lines together with its high optical and X-ray luminosity imply ... More
Observation of pseudogap behavior in a strongly interacting Fermi gasMar 04 2010Ultracold atomic Fermi gases present an opportunity to study strongly interacting Fermi systems in a controlled and uncomplicated setting. The ability to tune attractive interactions has led to the discovery of superfluidity in these systems with an extremely ... More
Predicting multiple planet stability and habitable zone companions in the TESS eraJan 31 2019We present an approach that is able to both rapidly assess the dynamical stability of multiple planet systems, and determine whether an exoplanet system would be capable of hosting a dynamically stable Earth-mass companion in its habitable zone. We conduct ... More
Effects of pitch and timing expectancy on musical emotionAug 11 2017Pitch and timing information work hand in hand to create a coherent piece of music; but what happens when this information goes against the norm? Relationships between musical expectancy and emotional responses were investigated in a study conducted with ... More
A deep ROSAT Survey - XIV. X-ray emission from faint galaxiesApr 14 1997Jun 24 1997We present a cross-correlation analysis to constrain the faint galaxy contribution to the cosmic X-ray background (XRB). Cross-correlating faint optical galaxy catalogues with unidentified X-ray sources from 3 deep ROSAT fields we find that B < 23 galaxies ... More
A deep ROSAT survey XV. the average QSO spectrum and its evolutionJan 11 2000Using a sample of 165 X-ray selected QSOs from seven deep ROSAT fields we investigate the X-ray spectral properties of an ``average''radio-quiet broad line QSO as a function of redshift. The QSO stacked spectra, in the observers 0.1-2 keV band, in five ... More
The Major and Minor Galaxy Merger Rates at z < 1.5Aug 11 2011Calculating the galaxy merger rate requires both a census of galaxies identified as merger candidates, and a cosmologically-averaged `observability' timescale T_obs(z) for identifying galaxy mergers. While many have counted galaxy mergers using a variety ... More
ASCA observations of deep ROSAT fields I. the nature of the X-ray source populationsApr 15 1997We present ASCA GIS observations (total exposure 100-200 ksec) of three fields which form part of our deep ROSAT survey. We detect 26 sources down to a limiting flux (2-10 keV) of 5x10^{-14} erg cm-2 s-1. Sources down to this flux level contribute 30 ... More
ASCA observations of deep ROSAT fields IV.IR and hard X-ray observations of an obscured high-redshift QSOOct 26 1998We use UKIRT and ASCA observations to determine the nature of a high redshift (z=2.35) narrow-line AGN, previously discovered by Almaini et al. (1995). The UKIRT observations show a broad Halpha line while no Hbeta line is detected. This together with ... More
Computational Topology for Regular Closed SetsFeb 26 2004The Boolean algebra of regular closed sets is prominent in topology, particularly as a dual for the Stone-Cech compactification. This algebra is also central for the theory of geometric computation, as a representation for combinatorial operations on ... More
On the problem of non-zero word error rates for fixed-rate error correction codes in continuous variable quantum key distributionMay 16 2016Mar 17 2017The maximum operational range of continuous variable quantum key distribution protocols has shown to be improved by employing high-efficiency forward error correction codes. Typically, the secret key rate model for such protocols is modified to account ... More
On dust entrainment in photoevaporative windsMar 09 2016May 10 2016We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodrodynamics (SPH). We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid ... More
Radiogenomics models in precision radiotherapy: from mechanistic to machine learningApr 21 2019Machine learning provides a broad framework for addressing high-dimensional prediction problems in classification and regression. While machine learning is often applied for imaging problems in medical physics, there are many efforts to apply these principles ... More
Atom--Molecule Coherence in a Bose-Einstein CondensateApr 20 2002Apr 30 2002Coherent coupling between atoms and molecules in a Bose-Einstein condensate (BEC) has been observed. Oscillations between atomic and molecular states were excited by sudden changes in the magnetic field near a Feshbach resonance and persisted for many ... More
ALMA images of discs: are all gaps carved by planets?Sep 02 2015Protoplanetary discs are now routinely observed and exoplanets, after the numerous indirect discoveries, are starting to be directly imaged. To better understand the planet formation process, the next step is the detection of forming planets or of signposts ... More
Projection of root systemsApr 03 2019Let $a$ be a real euclidean vector space of finite dimension and $\Sigma$ a root system in $a$ with a basis $\Delta$. Let $\Theta \subset \Delta$ and $M = M_{\Theta}$ be a standard Levi of a reductive group $G$ such that $a_{\Theta} = a_M\slash a_G$. ... More
The z=0.54 LoBAL Quasar SDSS J085053.12+445122.5: I. Spectral Synthesis Analysis Reveals a Massive OutflowAug 07 2018We introduce SimBAL, a novel spectral-synthesis procedure that uses large grids of ionic column densities generated by the photoionization code Cloudy and a Bayesian model calibration to forward-model broad absorption line quasar spectra. We used SimBAL ... More
Forecasting [C II] line-intensity mapping measurements between the end of reionization and the epoch of galaxy assemblyDec 19 2018We combine recent simulation work on the SFR--[C II] correlation at high redshift with empirical modeling of the galaxy--halo connection (via UniverseMachine) to forecast [C II] auto power spectra from $z\sim4$ to $z\sim8$. We compare these to sensitivities ... More
Collisional stripping of planetary crustsDec 07 2017Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of 'crustal stripping' ... More
Patterning Superconductivity in a Topological InsulatorOct 27 2016While topological superconductors are predicted to provide building blocks for fault-tolerant quantum computing, one of the remaining challenges is to find a convenient experimental platform that would allow patterning of circuits. We find that superconductivity ... More
On estimation of contamination from hydrogen cyanide in carbon monoxide line intensity mappingJun 09 2017Aug 31 2017Line-intensity mapping surveys probe large-scale structure through spatial variations in molecular line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide line emission, specifically the CO(1-0) line, ... More
The pinnacle set of a permutationApr 18 2017Peak sets of a permutation record the indices of its peaks. These sets have been studied in a variety of contexts, including recent work by Billey, Burdzy, and Sagan, which enumerated permutations with prescribed peak sets. In this article, we look at ... More
Direct Measurement of Interparticle Forces of Titan Aerosol Analogs ("Tholin") Using Atomic Force MicroscopyOct 17 2017Oct 18 2017To understand the origin of the dunes on Titan, it is important to investigate the material properties of Titan's organic sand particles on Titan. The organic sand may behave distinctively compared to the quartz/basaltic sand on terrestrial planets (Earth, ... More
String Breaking in Quenched QCDSep 10 1998Sep 15 1998We present preliminary quenched results on a new operator for the investigation of string-breaking within SU(2)-colour QCD. The ground-state of a spatially-separated static-light meson-antimeson pair is a combination of a state with two distinct mesons, ... More
Architecting Data Quality for Continuous Student Behaviour ManagementMay 16 2016Data capture and use is vital for the continuous improvement of both student learning and behavior management. Previous studies on data use in the education sector have highlighted a number of problems associated with data quality and its subsequent use. ... More
Self-Organization and The Origins of Life: The Managed-Metabolism HypothesisMay 18 2017The managed-metabolism hypothesis suggests that a cooperation barrier must be overcome if self-producing chemical organizations are to transition from non-life to life. This barrier prevents un-managed, self-organizing, autocatalytic networks of molecular ... More
The Self-Organizing Society: A Grower's GuideJun 02 2017Can a human society be constrained in such a way that self-organization will thereafter tend to produce outcomes that advance the goals of the society? Such a society would be self-organizing in the sense that individuals who pursue only their own interests ... More
UBe13 and U1-xThxBe13: Unconventional SuperconductorsDec 23 2018Jan 14 2019UBe13 was the second discovered heavy fermion superconductor, and numerous pieces of evidence exist that imply that it is an unconventional (non-BCS, non-s wave pairing symmetry) superconductor. Exhibiting even more signs of unconventional superconductivity, ... More
Correction: Stable homotopy classification of $BG_{p}^{\wedge}$Mar 03 2010We correct the proof of the main theorem of our paper of the same title (Topology, 34, no.3, 633-649, 1995).
String-breaking in quenched QCDNov 09 1998We present results on a new operator for the investigation of string-breaking effects in quenched SU(2)-colour QCD. The ground state of a spatially-separated static-light meson-antimeson pair is a combination of a state with two distinct mesons, expected ... More
Pushing NRQCD to the limitOct 13 1999Lattice NRQCD has proven successful in describing the physics of the upsilon system and B-mesons, though some concerns arise when it is used in simulations of charm quarks. It is certainly possible that the NRQCD expansion is not converging fast enough ... More
The second cohomology of simple SL_3-modulesJul 27 2009Nov 01 2018Let G be the simple, simply connected algebraic group SL_3 defined over an algebraically closed field K of characteristic p>0. In this paper, we find H^2(G,V) for any irreducible G-module V. When p>7 we also find H^2(G(q),V) for any irreducible G(q)-module ... More
Invisible Major Mergers: Why the Definition of a Galaxy Merger Ratio MattersFeb 13 2009The mapping between dark matter halo mass, galaxy stellar mass, and galaxy cold gas mass is not a simple linear relation, but is influenced by a wide array of galaxy formation processes. We implement observationally-normalized relations between dark matter ... More
A Dirichlet Regression Model for Compositional Data with ZerosOct 18 2014Jun 07 2017Compositional data are met in many different fields, such as economics, archaeometry, ecology, geology and political sciences. Regression where the dependent variable is a composition is usually carried out via a log-ratio transformation of the composition ... More
Stasis Points and Approximating Two-CyclesApr 18 2005Generically, every fixed point for the differential inclusion x' in ConvexHull{f_1,f_2} can be approximated by an arbitrarily small two-cycle for the inclusion x' in {f_1,f_2}, where f_1, f_2 are a C^1 flows on R^n.
On the Mathematics of Data Centre Network TopologiesMay 03 2016The theory of combinatorial designs has recently been used in order to build switch-centric data centre networks incorporating a large number of servers, in comparison with the popular Fat-Tree data centre network. The construction employed, called the ... More
A Collisional Origin to Earth's Non-chondritic Composition?Oct 13 2014Several lines of evidence indicate a non-chondritic composition for Bulk Earth. If Earth formed from the accretion of chondritic material, its non-chondritic composition, in particular the super-chondritic 142Nd/144Nd and low Mg/Fe ratios, might be explained ... More
Tidal evolution of the Moon from a high-obliquity, high-angular-momentum EarthFeb 09 2018In the giant impact hypothesis for lunar origin, the Moon accreted from an equatorial circum-terrestrial disk; however the current lunar orbital inclination of 5 degrees requires a subsequent dynamical process that is still debated. In addition, the giant ... More
Compositional evolution during rocky protoplanet accretionSep 24 2015The Earth appears non-chondritic in its abundances of refractory lithophile elements, posing a significant problem for our understanding of its formation and evolution. It has been suggested that this non-chondritic composition may be explained by collisional ... More
Multivariate Classification with Random Forests for Gravitational Wave Searches of Black Hole Binary CoalescenceDec 19 2014Searches for gravitational waves produced by coalescing black hole binaries with total masses $\gtrsim25\,$M$_\odot$ use matched filtering with templates of short duration. Non-Gaussian noise bursts in gravitational wave detector data can mimic short ... More
Delayed Impact of Fair Machine LearningMar 12 2018Apr 07 2018Fairness in machine learning has predominantly been studied in static classification settings without concern for how decisions change the underlying population over time. Conventional wisdom suggests that fairness criteria promote the long-term well-being ... More
Concentration and consistency results for canonical and curved exponential-family models of random graphsFeb 06 2017Dec 24 2018Statistical inference for exponential-family models of random graphs with dependent edges is challenging. We stress the importance of additional structure and show that additional structure facilitates statistical inference. A simple example of a random ... More
Unquenched Charmonium with NRQCDMay 29 2000Jan 29 2001We present the results from a series of lattice simulations of the charmonium system using a highly-improved NRQCD action, both in the quenched approximation, and with n_f = 2 light dynamical quarks. The spectra show some evidence for quenching effects ... More
An Efficient and Balanced Platform for Data-Parallel Subsampling WorkloadsApr 17 2014With the advent of internet services, data started growing faster than it can be processed. To personalize user experience, this enormous data has to be processed in real time, in interactive fashion. In order to achieve faster data processing often a ... More
Hadronic Molecules in Lattice QCDMar 02 1998An adiabatic approximation is used to derive the binding potential between two heavy-light mesons in quenched SU(2)-colour lattice QCD. Analysis of the meson-meson system shows that the potential is attractive at short- and medium-range. The numerical ... More
3-List Colouring Permutation GraphsApr 26 2011May 03 20113-list colouring is an NP-complete decision problem. It is hard even on planar bipartite graphs. We give a polynomial-time algorithm for solving 3-list colouring on permutation graphs.
Equivalence of the filament and overlap graphs of subtrees of limited treesAug 06 2015Jun 14 2017The overlap graphs of subtrees of a tree are equivalent to subtree filament graphs, the overlap graphs of subtrees of a star are cocomparability graphs, and the overlap graphs of subtrees of a caterpillar are interval filament graphs. In this paper, we ... More
On the eigenvalues of truncations of random unitary matricesNov 20 2018Apr 10 2019We consider the empirical eigenvalue distribution of an $m\times m$ principle submatrix of an $n\times n$ random unitary matrix distributed according to Haar measure. Earlier work of Petz and R\'effy identified the limiting spectral measure if $\frac{m}{n}\to\alpha$, ... More
Gas Accretion and Angular MomentumDec 01 2016In this chapter, we review the role of gas accretion to the acquisition of angular momentum, both in galaxies and in their gaseous halos. We begin by discussing angular momentum in dark matter halos, with a brief review of tidal torque theory and the ... More
The cyclotomic BMW algebra associated with the two string type B braid groupNov 17 2006Oct 07 2010The cyclotomic Birman-Murakami-Wenzl (or BMW) algebras B_n^k, introduced by R. Haring-Oldenburg, are extensions of the cyclotomic Hecke algebras of Ariki-Koike, in the same way as the BMW algebras are extensions of the Hecke algebras of type A. In this ... More
On the center of the ring of differential operators on a smooth variety over $\bZ/p^n\bZ$Apr 14 2011We compute the center of the ring of PD differential operators on a smooth variety over $\bZ/p^n\bZ$ confirming a conjecture of Kaledin. More generally, given an associative algebra $A_0$ over $\bF_p$ and its flat deformation $A_n$ over $\bZ/p^{n+1}\bZ$ ... More
Eigenvalue rigidity for truncations of random unitary matricesMay 06 2019We consider the empirical eigenvalue distribution of an $m\times m$ principal submatrix of an $n\times n$ random unitary matrix distributed according to Haar measure. For $n$ and $m$ large with $\frac{m}{n}=\alpha$, the empirical spectral measure is well-approximated ... More
Cyclic Approximation to K-StasisMar 10 2008Mar 28 2008If a linear combination of k smooth vector fields is zero at a point, then, generically, near this point there are small cycles comprised of segments from the flow of each vector field. This answers a question posed in arXiv:math/0504365.
Supermassive Black-hole Demographics & Environments With Pulsar Timing ArraysMar 19 2019Precision timing of large arrays (>50) of millisecond pulsars will detect the nanohertz gravitational-wave emission from supermassive binary black holes within the next ~3-7 years. We review the scientific opportunities of these detections, the requirements ... More
A Multi-Wavelength Perspective of Flares on HR 1099: Four Years of Coordinated CampaignsFeb 25 2004We report on four years of multiple wavelength observations of the RS CVn system V711 Tau (HR 1099) from 1993, 1994, 1996, and 1998. This combination of radio, ultraviolet, extreme ultraviolet, and X-ray observations allows us to view, in the most comprehensive ... More
The second cohomology of simple SL_3-modulesJul 27 2009Apr 10 2012Let G be the simple, simply connected algebraic group SL_3 defined over an algebraically closed field K of characteristic p>0. In this paper, we find H^2(G,V) for any irreducible G-module V. When p>7 we also find H^2(G(q),V) for any irreducible G(q)-module ... More
Transfer and complex oriented cohomology ringsJul 12 2003For finite coverings we elucidate the interaction between transferred Chern classes and Chern classes of transferred bundles. This involves computing the ring structure for the complex oriented cohomology of various homotopy orbit spaces. In turn these ... More
A Short Note on Nonlinear Games on a GridJul 30 2015Players are arranged on a regular lattice and coded with a specific strategy for a pre-defined game. Each player sums their payoffs from playing the game with each of their neighbors, and then adopts the strategy of the most successful player in the neighborhood. ... More
The second cohomology of simple SL_2-modulesApr 03 2009Jul 27 2009Let $G$ be the simple algebraic group $SL_2$ defined over an algebraically closed field $K$ of characteristic $p>0$. In this paper, we find the second cohomology of all irreducible representations of $G$
On the minimal modules for exceptional Lie algebras: Jordan blocks and stabilisersAug 12 2015Apr 21 2017Let G be a simple simple-connected exceptional algebraic group of type G_2, F_4, E_6 or E_7 over an algebraically closed field k of characteristic p>0 with \g=Lie(G). For each nilpotent orbit G.e of \g, we list the Jordan blocks of the action of e on ... More