Results for "Gregory B. Poole"

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The simplest model of galaxy formation I: A formation history model of galaxy stellar mass growthApr 09 2013Sep 04 2013We introduce a simple model to self-consistently connect the growth of galaxies to the formation history of their host dark matter haloes. Our model is defined by two simple functions: the "baryonic growth function" which controls the rate at which new ... More
The mid-life crisis of the Milky Way and M31May 12 2011Upcoming next generation galactic surveys, such as GAIA and HERMES, will deliver unprecedented detail about the structure and make-up of our Galaxy, the Milky Way, and promise to radically improve our understanding of it. However, to benefit our broader ... More
Parallelized Inference for Gravitational-Wave AstronomyApr 05 2019Bayesian inference is the workhorse of gravitational-wave astronomy, for example, determining the mass and spins of merging black holes, revealing the neutron star equation of state, and unveiling the population properties of compact binaries. The science ... More
Globular clusters and supermassive black holes in galaxies: further analysis and a larger sampleDec 18 2013We explore several correlations between various large-scale galaxy properties, particularly total globular cluster population (N_GCS), the central black hole mass (M_BH), velocity dispersion (nominally sigma_e), and bulge mass (M_dyn). Our data sample ... More
Dark-ages Reionization and Galaxy Formation Simulation - XVII. Sizes, angular momenta and morphologies of high redshift galaxiesApr 02 2019We study the sizes, angular momenta and morphologies of high-redshift galaxies using an update of the Meraxes semi-analytic galaxy evolution model. Our model successfully reproduces a range of observations from redshifts $z=0$-$10$. We find that the effective ... More
Models of the ICM with Heating and Cooling: Explaining the Global and Structural X-ray Properties of ClustersJun 14 2004(Abridged) Theoretical models that include only gravitationally-driven processes fail to match the observed mean X-ray properties of clusters. As a result, there has recently been increased interest in models in which either radiative cooling or entropy ... More
The impact of mergers on relaxed X-ray clusters - I. Dynamical evolution and emergent transient structuresAug 25 2006We report on the analysis of a suite of SPH simulations (incorporating cooling and star formation) of mergers involving idealised X-ray clusters whose initial conditions resemble relaxed clusters with cool compact cores observed by Chandra and XMM. The ... More
Physical Implications of the X-ray Properties of Galaxy Groups and ClustersSep 19 2001Dec 13 2001Within the standard framework of structure formation, where clusters and groups of galaxies are built up from the merging of smaller systems, the physical properties of the intracluster medium, such as the gas temperature and the total X-ray luminosity, ... More
Scaling Relations of Star-Forming Regions: from kpc-size clumps to HII regionsMar 01 2012We present the properties of 8 star-forming regions, or 'clumps,' in 3 galaxies at z~1.3 from the WiggleZ Dark Energy Survey, which are resolved with the OSIRIS integral field spectrograph. Within turbulent discs, \sigma~90 km/s, clumps are measured with ... More
Dark-ages Reionization and Galaxy Formation Simulation - XV. Stellar evolution and feedback in dwarf galaxies at high redshiftAug 10 2018We directly compare predictions of dwarf galaxy properties in a semi-analytic model (SAM) with those extracted from a high-resolution hydrodynamic simulation. We focus on galaxies with halo masses of 1e9<Mvir/Msol<1e11 at high redshift ($z\ge5$). We find ... More
Dark ages reionization & galaxy formation simulation XII: Bubbles at dawnApr 18 2017Jul 21 2017Direct detection of regions of ionized hydrogen (HII) has been suggested as a promising probe of cosmic reionization. Observing the redshifted 21-cm signal of hydrogen from the epoch of reionization (EoR) is a key scientific driver behind new-generation, ... More
Dark-ages Reionization and Galaxy Formation Simulation - XIII. AGN quenching of high-redshift star formation in ZF-COSMOS-20115Apr 11 2017Aug 25 2017Massive quiescent galaxies (MQGs) are thought to have formed stars rapidly at early times followed by a long period of quiescence. The recent discovery of a MQG, ZF-COSMOS-20115 at $z\sim4$, only 1.5 Gyr after the big bang, places new constraints on galaxy ... More
What is an Optimal Diagnosis?Mar 27 2013Within diagnostic reasoning there have been a number of proposed definitions of a diagnosis, and thus of the most likely diagnosis, including most probable posterior hypothesis, most probable interpretation, most probable covering hypothesis, etc. Most ... More
Dark-ages Reionization and Galaxy Formation Simulation - XIV. Gas accretion, cooling and star formation in dwarf galaxies at high redshiftFeb 12 2018Aug 06 2018We study dwarf galaxy formation at high redshift ($z\ge5$) using a suite of high- resolution, cosmological hydrodynamic simulations and a semi-analytic model (SAM). We focus on gas accretion, cooling and star formation in this work by isolating the relevant ... More
Dark-Ages Reionisation & Galaxy Formation Simulation XVI: The Thermal Memory of ReionisationApr 12 2019Intergalactic medium temperature is a powerful probe of the epoch of reionisation, as information is retained long after reionisation itself. However, mean temperatures are highly degenerate with the timing of reionisation, with the amount heat injected ... More
The impact of mergers on relaxed X-ray clusters - II. Effects on global X-ray and SZ properties and their scaling relationsJan 20 2007We use the suite of simulations presented in Poole et al (2006) to examine global X-ray and Sunyaev-Zel'dovich (SZ) observables for systems of merging relaxed X-ray clusters. In all of the scaling relations generated from the properties we have studied, ... More
Dark-ages Reionization and Galaxy Formation Simulation - X. The small contribution of quasars to reionizationMar 15 2017Sep 26 2017Motivated by recent measurements of the number density of faint AGN at high redshift, we investigate the contribution of quasars to reionization by tracking the growth of central supermassive black holes in an update of the Meraxes semi-analytic model. ... More
Dark-ages reionization and galaxy formation simulation XI: Clustering and halo masses of high redshift galaxiesMar 15 2017Sep 15 2017We investigate the clustering properties of Lyman-break galaxies (LBGs) at $z\sim6$ - $8$. Using the semi-analytical model {\scshape Meraxes} constructed as part of the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulation ... More
Dark-ages reionization & galaxy formation simulation IV: UV luminosity functions of high-redshift galaxiesDec 02 2015Apr 27 2016In this paper we present calculations of the UV luminosity function from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project, which combines N-body, semi-analytic and semi-numerical modelling designed ... More
Dark-ages Reionization & Galaxy Formation Simulation I: The dynamical lives of high redshift galaxiesDec 02 2015Mar 21 2016We present the Dark-ages Reionization and Galaxy-formation Observables from Numerical Simulations (DRAGONS) program and Tiamat, the collisionless N-body simulation program upon which DRAGONS is built. The primary trait distinguishing Tiamat from other ... More
Dark-ages reionization & galaxy formation simulation V: morphology and statistical signatures of reionizationDec 02 2015Aug 15 2016We use the Dark-ages, Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) framework to investigate the effect of galaxy-formation physics on the morphology and statistics of ionized hydrogen (HII) regions during the Epoch ... More
Dark-ages reionization and galaxy formation simulation - III. Modelling galaxy formation and the epoch of reionizationDec 02 2015Aug 18 2016We introduce Meraxes, a new, purpose-built semi-analytic galaxy formation model designed for studying galaxy growth during reionization. Meraxes is the first model of its type to include a temporally and spatially coupled treatment of reionization and ... More
Dark-ages reionization and galaxy formation simulation - IX. Economics of reionizing galaxiesMay 20 2017Jun 19 2017Using a series of high-resolution hydrodynamical simulations we show that during the rapid growth of high-redshift (z > 5) galaxies, reserves of molecular gas are consumed over a time-scale of 300Myr, almost independent of feedback scheme. We find that ... More
Dark-ages Reionization & Galaxy Formation Simulation II: Spin and concentration parameters for dark matter haloes during the Epoch of ReionizationDec 02 2015We use high resolution N-Body simulations to study the concentration and spin parameters of dark matter haloes in the mass range $10^8\, {\rm M}_{\odot}\, h^{-1} < {\rm M} < 10^{11}\, {\rm M}_{\odot}\, h^{-1}$ and redshifts $5{<}z{<}10$, corresponding ... More
Dark-ages Reionization & Galaxy Formation Simulation VIII. Suppressed growth of dark matter halos during the Epoch of ReionizationJan 13 2017Feb 21 2017We investigate how the hydrostatic suppression of baryonic accretion affects the growth rate of dark matter halos during the Epoch of Reionization. By comparing halo properties in a simplistic hydrodynamic simulation in which gas only cools adiabatically, ... More
Dark-ages reionization and galaxy formation simulation--VII. The sizes of high-redshift galaxiesAug 02 2016Nov 08 2016We investigate high-redshift galaxy sizes using a semi-analytic model constructed for the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulation project. Our fiducial model, including strong feedback from supernovae and photoionization ... More
Semi-Analytic Galaxy Evolution (SAGE): Model Calibration and Basic ResultsJan 18 2016Jan 22 2016This paper describes a new publicly available codebase for modelling galaxy formation in a cosmological context, the "Semi-Analytic Galaxy Evolution" model, or SAGE for short. SAGE is a significant update to that used in Croton et al. (2006) and has been ... More
Continuous and Discrete Homotopy Operators: A Theoretical Approach made ConcreteOct 25 2005Jun 28 2006Using standard calculus, explicit formulas for the one-dimensional continuous and discrete homotopy operators are derived. It is shown that these formulas are equivalent to those in terms of Euler operators obtained from the variational complex. The continuous ... More
Stages of Homogeneous Nucleation in Solid Isotopic Helium MixturesNov 21 2007We have made pressure and NMR measurements during the evolution of phase separation in solid helium isotopic mixtures. Our observations indicate clearly all three stages of the homogeneous nucleation - growth process: 1) creation of nucleation sites; ... More
The 2-degree Field Lensing Survey: photometric redshifts from a large new training sample to r<19.5Dec 01 2016We present a new training set for estimating empirical photometric redshifts of galaxies, which was created as part of the 2dFLenS project. This training set is located in a 700 sq deg area of the KiDS South field and is randomly selected and nearly complete ... More
KECK/MOSFIRE spectroscopic confirmation of a Virgo-like cluster ancestor at z=2.095Oct 02 2014We present the spectroscopic confirmation of a galaxy cluster at $z=2.095$ in the COSMOS field. This galaxy cluster was first reported in the ZFOURGE survey as harboring evolved massive galaxies using photometric redshifts derived with deep near-infrared ... More
On the Intracluster Medium in Cooling Flow & Non-Cooling Flow ClustersSep 19 2003Recent X-ray observations have highlighted clusters that lack entropy cores. At first glance, these results appear to invalidate the preheated ICM models. We show that a self-consistent preheating model, which factors in the effects of radiative cooling, ... More
A Color-Magnitude Diagram for a Globular Cluster In the Giant Elliptical Galaxy NGC 5128Jun 30 1998The Hubble Space Telescope has been used to obtain WFPC2 (V,I) photometry for a large sample of stars in the outer halo of the giant elliptical NGC 5128 (d = 4 Mpc). The globular cluster N5128-C44, at the center of the Planetary Camera field, is well ... More
Dipole Septum Magnet in the Fast Kicker System for Multi-Axis Advanced RadiographyOct 02 2000Here we present designs for a static septum magnet with two adjacent apertures where ideally one aperture has a uniform dipole field and the other zero field. Two designs are considered. One is a true septum magnet with a thin layer of coils and materials ... More
The Metallicity Distribution in the Halo Stars of NGC 5128: Implications for Galaxy FormationOct 08 1998The Hubble Space Telescope has been used to obtain WFPC2 (V,I) photometry for a sample of 10,000 red giant stars in the outer halo of the giant elliptical NGC 5128. Comparison with the fiducial RGBs of Milky Way globular clusters and model isochrones ... More
Initial Data for Numerical RelativityJul 31 2000Initial data are the starting point for any numerical simulation. In the case of numerical relativity, Einstein's equations constrain our choices of these initial data. We will examine several of the formalisms used for specifying Cauchy initial data ... More
The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshiftsNov 27 2009Aug 04 2010Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z<0.35) for bright ... More
2dFLenS and KiDS: Determining source redshift distributions with cross-correlationsNov 22 2016We develop a statistical estimator to infer the redshift probability distribution of a photometric sample of galaxies from its angular cross-correlation in redshift bins with an overlapping spectroscopic sample. This estimator is a minimum variance weighted ... More
The WiggleZ Dark Energy Survey: measuring the cosmic growth rate with the two-point galaxy correlation functionFeb 21 2013The growth history of large-scale structure in the Universe is a powerful probe of the cosmological model, including the nature of dark energy. We study the growth rate of cosmic structure to redshift $z = 0.9$ using more than $162{,}000$ galaxy redshifts ... More
The WiggleZ Dark Energy Survey: the selection function and z=0.6 galaxy power spectrumMar 30 2010We report one of the most accurate measurements of the three-dimensional large-scale galaxy power spectrum achieved to date, using 56,159 redshifts of bright emission-line galaxies at effective redshift z=0.6 from the WiggleZ Dark Energy Survey at the ... More
The WiggleZ Dark Energy Survey: Star-formation in UV-luminous galaxies from their luminosity functionsJun 17 2013We present the ultraviolet (UV) luminosity function of galaxies from the GALEX Medium Imaging Survey with measured spectroscopic redshifts from the first data release of the WiggleZ Dark Energy Survey. This sample selects galaxies with high star formation ... More
The WiggleZ Dark Energy Survey: Probing the Epoch of Radiation Domination using Large Scale StructureNov 23 2012Nov 03 2015We place the most robust constraint to date on the scale of the turnover in the cosmological matter power spectrum using data from the WiggleZ Dark Energy Survey. We find this feature to lie at a scale of $k_0=0.0160^{+0.0041}_{-0.0035}$ [h/Mpc] (68% ... More
KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clusteringJul 20 2017Nov 08 2017We perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography, and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg$^2$ of imaging data by the Kilo Degree Survey (KiDS) overlapping with two spectroscopic ... More
The 2-degree Field Lensing Survey: design and clustering measurementsAug 09 2016We present the 2-degree Field Lensing Survey (2dFLenS), a new galaxy redshift survey performed at the Anglo-Australian Telescope. 2dFLenS is the first wide-area spectroscopic survey specifically targeting the area mapped by deep-imaging gravitational ... More
The Stellar Masses of ~40,000 UV Selected Galaxies from the WiggleZ Survey at 0.3<z<1.0: Analogues of Lyman Break Galaxies?Feb 20 2013We characterise the stellar masses and star formation rates in a sample of almost 40000 spectroscopically confirmed UV luminous galaxies at 0.3<z<1.0 selected from within the WiggleZ Dark Energy Survey. In particular, we match this UV bright population ... More
The WiggleZ Dark Energy Survey: High Resolution Kinematics of Luminous Star-Forming GalaxiesJul 17 2011We report evidence of ordered orbital motion in luminous star-forming galaxies at z~1.3. We present integral field spectroscopy (IFS) observations, performed with the OH Suppressing InfraRed Imaging Spectrograph (OSIRIS) system, assisted by laser guide ... More
First Results from Z-FOURGE: Discovery of a Candidate Cluster at z = 2.2 in COSMOSDec 12 2011Mar 05 2012We report the first results from the Z-FOURGE survey: the discovery of a candidate galaxy cluster at z = 2.2 consisting of two compact overdensities with red galaxies detected at >20{\sigma} above the mean surface density. The discovery was made possible ... More
On Weak Hamiltonicity of a Random HypergraphOct 27 2014A {\it weak (Berge) cycle} is an alternating sequence of vertices and (hyper)edges $C=(v_0, e_1, v_1, ..., v_{\ell-1}, e_\ell, v_{\ell}=v_0)$ such that the vertices $v_0, ..., v_{\ell-1}$ are distinct with $v_k, v_{k+1} \in e_{k}$ for each $k$, but the ... More
Testing Closeness With Unequal Sized SamplesApr 17 2015We consider the problem of closeness testing for two discrete distributions in the practically relevant setting of \emph{unequal} sized samples drawn from each of them. Specifically, given a target error parameter $\varepsilon > 0$, $m_1$ independent ... More
Modes of the Kerr geometry with purely imaginary frequenciesJul 25 2016In this paper, we examine the behavior of modes of the Kerr geometry when the mode's frequency is purely imaginary. We demonstrate that quasinormal modes must be polynomial in nature if their frequency is purely imaginary, and present a method for computing ... More
The Satisfiability Threshold of Random 3-SAT Is at Least 3.52Oct 13 2003Oct 22 2003We prove that a random 3-SAT instance with clause-to-variable density less than 3.52 is satisfiable with high probability. The proof comes through an algorithm which selects (and sets) a variable depending on its degree and that of its complement.
The Satisfiability Threshold for k-XORSATDec 09 2012Aug 03 2014We consider "unconstrained" random $k$-XORSAT, which is a uniformly random system of $m$ linear non-homogeneous equations in $\mathbb{F}_2$ over $n$ variables, each equation containing $k \geq 3$ variables, and also consider a "constrained" model where ... More
VCG Auction Mechanism Cost Expectations and VariancesOct 07 2013We consider Vickrey-Clarke-Groves (VCG) auctions for a very general combinatorial structure, in an average-case setting where item costs are independent, identically distributed uniform random variables. We prove that the expected VCG cost is at least ... More
On the strength of connectedness of a random hypergraphSep 04 2014Mar 09 2015Bollob\'{a}s and Thomason (1985) proved that for each $k=k(n) \in [1, n-1]$, with high probability, the random graph process, where edges are added to vertex set $V=[n]$ uniformly at random one after another, is such that the stopping time of having minimal ... More
Electric field control of chiral magnetic domains in the high-temperature multiferroic CuOJan 16 2012We have studied the high temperature multiferroic cupric oxide using polarized neutron diffraction as a function of temperature and applied electric field. We find that the chiral domain population can be varied using an external electric field applied ... More
The WiggleZ Dark Energy Survey: Survey Design and First Data ReleaseNov 22 2009Nov 24 2009The WiggleZ Dark Energy Survey is a survey of 240,000 emission line galaxies in the distant universe, measured with the AAOmega spectrograph on the 3.9-m Anglo-Australian Telescope (AAT). The target galaxies are selected using ultraviolet photometry from ... More
The WiggleZ Dark Energy Survey: Final data release and cosmological resultsOct 08 2012This paper presents cosmological results from the final data release of the WiggleZ Dark Energy Survey. We perform full analyses of different cosmological models using the WiggleZ power spectra measured at z=0.22, 0.41, 0.60, and 0.78, combined with other ... More
The WiggleZ Dark Energy Survey: Improved Distance Measurements to z = 1 with Reconstruction of the Baryonic Acoustic FeatureJan 02 2014Jul 28 2014We present significant improvements in cosmic distance measurements from the WiggleZ Dark Energy Survey, achieved by applying the reconstruction of the baryonic acoustic feature technique. We show using both data and simulations that the reconstruction ... More
The WiggleZ Dark Energy Survey: Cosmological neutrino mass constraint from blue high-redshift galaxiesDec 21 2011Apr 16 2012The absolute neutrino mass scale is currently unknown, but can be constrained from cosmology. The WiggleZ high redshift star-forming blue galaxy sample is less sensitive to systematics from non-linear structure formation, redshift-space distortions and ... More
Using the topology of large-scale structure in the WiggleZ Dark Energy Survey as a cosmological standard rulerOct 25 2013We present new and accurate measurements of the cosmic distance-redshift relation, spanning 0.2 < z < 1, using the topology of large-scale structure as a cosmological standard ruler. Our results derive from an analysis of the Minkowski functionals of ... More
Determining accurate measurements of the growth rate from the galaxy correlation function in simulationsFeb 21 2013We use high-resolution N-body simulations to develop a new, flexible, empirical approach for measuring the growth rate from redshift-space distortions (RSD) in the 2-point galaxy correlation function. We quantify the systematic error in measuring the ... More
Lower and Upper Bound for Computing the Size of All Second NeighbourhoodsMay 04 2018We consider the problem of computing the size of each $r$-neighbourhood for every vertex of a graph. Specifically, we ask whether the size of the closed second neighbourhood can be computed in subquadratic time. Adapting the SETH reductions by Abboud ... More
Approximate Killing Vectors on S^2Jun 01 2007We present a new method for computing the best approximation to a Killing vector on closed 2-surfaces that are topologically S^2. When solutions of Killing's equation do not exist, this method is shown to yield results superior to those produced by existing ... More
Collisions of boosted black holes: perturbation theory prediction of gravitational radiationMay 23 1994Jun 01 1994We consider general relativistic Cauchy data representing two nonspinning, equal-mass black holes boosted toward each other. When the black holes are close enough to each other and their momentum is sufficiently high, an encompassing apparent horizon ... More
The Renormalization Group and its Finite Lattice ApproximationsDec 15 1998We investigate finite lattice approximations to the Wilson Renormalization Group in models of unconstrained spins. We discuss first the properties of the Renormalization Group Transformation (RGT) that control the accuracy of this type of approximations ... More
Polynomial Constraint Satisfaction, Graph Bisection, and the Ising Partition FunctionApr 20 2006Apr 01 2009We introduce a problem class we call Polynomial Constraint Satisfaction Problems, or PCSP. Where the usual CSPs from computer science and optimization have real-valued score functions, and partition functions from physics have monomials, PCSP has scores ... More
Excision boundary conditions for black hole initial dataJul 21 2004Apr 01 2005We define and extensively test a set of boundary conditions that can be applied at black hole excision surfaces when the Hamiltonian and momentum constraints of general relativity are solved within the conformal thin-sandwich formalism. These boundary ... More
Searching for Maximum Out-Degree Vertices in TournamentsJan 15 2018A vertex $x$ in a tournament $T$ is called a king if for every vertex $y$ of $T$ there is a directed path from $x$ to $y$ of length at most 2. It is not hard to show that every vertex of maximum out-degree in a tournament is a king. However, tournaments ... More
The Interlace Polynomial of a GraphSep 04 2002Aug 13 2004Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable ``interlace polynomial'' for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and fuse reduction ... More
A Two-Variable Interlace PolynomialSep 05 2002Aug 13 2004We introduce a new graph polynomial in two variables. This ``interlace'' polynomial can be computed in two very different ways. The first is an expansion analogous to the state space expansion of the Tutte polynomial; the significant differences are that ... More
A tight bound on the collection of edges in MSTs of induced subgraphsMay 16 2007Let $G=(V,E)$ be a complete $n$-vertex graph with distinct positive edge weights. We prove that for $k\in\{1,2,...,n-1\}$, the set consisting of the edges of all minimum spanning trees (MSTs) over induced subgraphs of $G$ with $n-k+1$ vertices has at ... More
Variability in Optical Spectra of epsilon OrionisJan 23 2013Mar 02 2013We present the results of a time-series analysis of 130 echelle spectra of epsilon Ori (B0 Ia), acquired over seven observing seasons between 1998 and 2006 at Ritter Observatory. The equivalent widths of Halpha (net) and He I 5876 were measured and radial ... More
The rational homotopy type of the space of self-equivalences of a fibrationMar 09 2009Sep 04 2010Let Aut(p) denote the topological monoid of self-fibre-homotopy equivalences of a fibration p:E\to B. We make a general study of this monoid, especially in rational homotopy theory. When E and B are simply connected CW complexes with E finite, we identify ... More
Inspiral, merger and ring-down of equal-mass black-hole binariesOct 25 2006Jun 22 2007We investigate the dynamics and gravitational-wave (GW) emission in the binary merger of equal-mass black holes as obtained from numerical relativity simulations. Results from the evolution of three sets of initial data are explored in detail, corresponding ... More
Non-degenerate graded Lie algebras with a degenerate transitive subalgebraJan 28 2009Feb 17 2009The property of degeneration of modular graded Lie algebras, first investigated by B. Weisfeiler, is analyzed. Transitive irreducible graded Lie algebras $L=\sum_{i\in \mathbb Z}L_i,$ over an algebraically closed field of characteristic $p>2,$ with classical ... More
Constraining the last 7 billion years of galaxy evolution in semi-analytic modelsOct 11 2012Nov 30 2012We investigate the ability of the Croton et al. (2006) semi-analytic model to reproduce the evolution of observed galaxies across the final 7 billion years of cosmic history. Using Monte-Carlo Markov Chain techniques we explore the available parameter ... More
Structure of random r-SAT below the pure literal thresholdAug 06 2010It is well known that there is a sharp density threshold for a random $r$-SAT formula to be satisfiable, and a similar, smaller, threshold for it to be satisfied by the pure literal rule. Also, above the satisfiability threshold, where a random formula ... More
Online Sum-Paintability: Slow-Coloring of TreesDec 14 2016Oct 02 2017The slow-coloring game is played by Lister and Painter on a graph $G$. On each round, Lister marks a nonempty subset $M$ of the remaining vertices, scoring $|M|$ points. Painter then gives a color to a subset of $M$ that is independent in $G$. The game ... More
How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulationsDec 03 2015Galaxy clusters are an established and powerful test-bed for theories of both galaxy evolution and cosmology. Accurate interpretation of cluster observations often requires robust identification of the location of the centre. Using a statistical sample ... More
Consistency of non-minimal renormalisation schemesMar 23 2016Non-minimal renormalisation schemes such as the momentum subtraction scheme (MOM) have frequently been used for physical computations. The consistency of such a scheme relies on the existence of a coupling redefinition linking it to MSbar. We discuss ... More
Representing Bayesian Networks within Probabilistic Horn AbductionMar 20 2013This paper presents a simple framework for Horn clause abduction, with probabilities associated with hypotheses. It is shown how this representation can represent any probabilistic knowledge representable in a Bayesian belief network. The main contributions ... More
On the applicability of the two-band model to describe transport across n-p junctions in bilayer grapheneJan 11 2010We extend the low-energy effective two-band Hamiltonian for electrons in bilayer graphene (E. McCann, V. I. Fal'ko, Phys. Rev. Lett. 96 (2006) 86805) to include a spatially dependent electrostatic potential. We find that this Hamiltonian contains additional ... More
Coupling of magnetic and ferroelectric hysteresis by a multi-component magnetic structure in Mn2GeO4Aug 06 2012The olivine compound Mn2GeO4 is shown to feature both a ferroelectric polarization and a ferromagnetic magnetization that are directly coupled and point along the same direction. We show that a spin spiral generates ferroelectricity (FE), and a canted ... More
The homotopy operator method for symbolic integration by parts and inversion of divergences with applicationsAug 04 2009Aug 20 2009Using standard calculus, explicit formulas for one-, two- and three-dimensional homotopy operators are presented. A derivation of the one-dimensional homotopy operator is given. A similar methodology can be used to derive the multi-dimensional versions. ... More
A Framework for Decision-Theoretic Planning I: Combining the Situation Calculus, Conditional Plans, Probability and UtilityFeb 13 2013This paper shows how we can combine logical representations of actions and decision theory in such a manner that seems natural for both. In particular we assume an axiomatization of the domain in terms of situation calculus, using what is essentially ... More
Symbolic computation of conservation laws for nonlinear partial differential equations in multiple space dimensionsJul 29 2010Aug 04 2011A method for symbolically computing conservation laws of nonlinear partial differential equations (PDEs) in multiple space dimensions is presented in the language of variational calculus and linear algebra. The steps of the method are illustrated using ... More
Exploiting the Rule Structure for Decision Making within the Independent Choice LogicFeb 20 2013This paper introduces the independent choice logic, and in particular the "single agent with nature" instance of the independent choice logic, namely ICLdt. This is a logical framework for decision making uncertainty that extends both logic programming ... More
Context-Specific Approximation in Probabilistic InferenceJan 30 2013There is evidence that the numbers in probabilistic inference don't really matter. This paper considers the idea that we can make a probabilistic model simpler by making fewer distinctions. Unfortunately, the level of a Bayesian network seems too coarse; ... More
Birth of a giant $(k_1,k_2)$-core in the random digraphAug 17 2016The $(k_1,k_2)$-core of a digraph is the largest sub-digraph with minimum in-degree and minimum out-degree at least $k_1$ and $k_2$ respectively. For $\max\{k_1, k_2\} \geq 2$, we establish existence of the threshold edge-density $c^*=c^*(k_1,k_2)$, such ... More
CANDELS Visual Classifications: Scheme, Data Release, and First ResultsJan 10 2014Oct 09 2015We have undertaken an ambitious program to visually classify all galaxies in the five CANDELS fields down to H<24.5 involving the dedicated efforts of 65 individual classifiers. Once completed, we expect to have detailed morphological classifications ... More
Why is Compiling Lifted Inference into a Low-Level Language so Effective?Jun 14 2016First-order knowledge compilation techniques have proven efficient for lifted inference. They compile a relational probability model into a target circuit on which many inference queries can be answered efficiently. Early methods used data structures ... More
Robust split-step Fourier methods for simulating the propagation of ultra-short pulses in single- and two-mode optical communication fibersApr 06 2015Extensions of the split-step Fourier method (SSFM) for Schr\"odinger-type pulse propagation equations for simulating femto-second pulses in single- and two-mode optical communication fibers are developed and tested for Gaussian pulses. The core idea of ... More
High Level Path Planning with UncertaintyMar 20 2013For high level path planning, environments are usually modeled as distance graphs, and path planning problems are reduced to computing the shortest path in distance graphs. One major drawback of this modeling is the inability to model uncertainties, which ... More
Low-mass galaxy formation and the ionizing photon budget during reionizationMay 29 2014Jul 20 2014We use high-resolution simulations of cosmological volumes to model galaxy formation at high-redshift, with the goal of studying the photon budget for reionization. We demonstrate that galaxy formation models that include a strong, thermally coupled supernovae ... More
Bulk high-Tc superconductors with drilled holes: how to arrange the holes to maximize the trapped magnetic flux ?Nov 12 2008Drilling holes in a bulk high-Tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid. However, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. In this paper, we use the ... More
A numerical study of the correspondence between paths in a causal set and geodesics in the continuumDec 13 2005This paper presents the results of a computational study related to the path-geodesic correspondence in causal sets. For intervals in flat spacetimes, and in selected curved spacetimes, we present evidence that the longest maximal chains (the longest ... More
Hamiltonian lattice QCD at finite chemical potentialDec 25 1999Aug 03 2000At sufficiently high temperature and density, quantum chromodynamics (QCD) is expected to undergo a phase transition from the confined phase to the quark-gluon plasma phase. In the Lagrangian lattice formulation the Monte Carlo method works well for QCD ... More
Universal non stationary dynamics at the depinning transitionJun 13 2009We study the non-stationary dynamics of an elastic interface in a disordered medium at the depinning transition. We compute the two-time response and correlation functions, found to be universal and characterized by two independent critical exponents. ... More
Comment on "Evidence for a small hole pocket in the Fermi surface of underdoped YBa2Cu3Oy; [arXiv:1409.2788v1]"Sep 16 2014Oct 06 2014N. Doiron-Leyraud et al. in [1] report on the experimental observation of small holes pockets in the energy spectrum of YBa2Cu3Oy (YBCO) coming below the transition into the charge ordered (CO) phase as a result of a Fermi surface (FS) reconstruction. ... More
Zero field entanglement in dipolar coupling spin system at negative temperaturesSep 21 2013A dipolar coupled spin system can achieve internal thermodynamic equilibrium states at negative absolute temperature. We study analytically and numerically the temperature dependence of the concurrence in a dipolar coupled spin-1/2 system in both non-zero ... More