Results for "Simon J. Mutch"

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Building disc structure and galaxy properties through angular momentum: The DARK SAGE semi-analytic modelMay 02 2016Jun 24 2016We present the new semi-analytic model of galaxy evolution, DARK SAGE, a heavily modified version of the publicly available SAGE code. The model is designed for detailed evolution of galactic discs. We evolve discs in a series of annuli with fixed specific ... 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
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
The growth of disks and bulges during hierarchical galaxy formation. I: fast evolution vs secular processesApr 07 2016Apr 20 2016We present a theoretical model for the evolution of mass, angular momentum and size of galaxy disks and bulges, and we implement it into the semi-analytic galaxy formation code SAGE. The model follows both secular and violent evolutionary channels, including ... More
The growth of disks and bulges during hierarchical galaxy formation. II: metallicity, stellar populations and dynamical evolutionJun 20 2016We investigate the properties of the stellar populations of model galaxies, using the new semi-analytic model presented in Tonini et al. (2016a). This new model follows the angular momentum evolution of gas and stars, providing the base for a new star ... More
Convergence properties of halo merger trees; halo and substructure merger rates across cosmic historySep 05 2017We introduce gbpTrees: an algorithm for constructing merger trees from cosmological simulations, designed to identify and correct for pathological cases introduced by errors or ambiguities in the halo finding process. gbpTrees is built upon a halo matching ... 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
Model dispersion with PRISM; an alternative to MCMC for rapid analysis of modelsJan 25 2019We have built PRISM, a "Probabilistic Regression Instrument for Simulating Models". PRISM uses the Bayes linear approach and history matching to construct an approximation ('emulator') of any given model, by combining limited model evaluations with advanced ... More
Do you see what I see? Exploring the consequences of luminosity limits in black hole-galaxy evolution studiesJun 01 2017Jun 05 2017In studies of the connection between active galactic nuclei (AGN) and their host galaxies there is widespread disagreement on some key aspects stemming largely from a lack of understanding of the nature of the full underlying AGN population. Recent attempts ... More
Dark-ages Reionization and Galaxy Formation Simulation - XIV. Gas accretion, cooling and star formation in dwarf galaxies at high redshiftFeb 12 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 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
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 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 & 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
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
The Gigaparsec WiggleZ Simulations: Characterising scale dependant bias and associated systematics in growth of structure measurementsJul 01 2014Nov 03 2015We use the Gigaparsec WiggleZ (GiggleZ) simulations to characterise galaxy bias and its scale dependence for a range of redshifts and halo masses in a standard $\Lambda$LCDM cosmology. Assuming bias converges to a scale independent form at large scales, ... More
The Theoretical Astrophysical Observatory: Cloud-Based Mock Galaxy CataloguesMar 20 2014Jan 22 2016We introduce the Theoretical Astrophysical Observatory (TAO), an online virtual laboratory that houses mock observations of galaxy survey data. Such mocks have become an integral part of the modern analysis pipeline. However, building them requires an ... More
Dark-ages reionization & galaxy formation simulation VI: The origins and fate of the highest known redshift galaxyMay 25 2016Using Hubble data, including new grism spectra, Oesch et al. (2016) recently identified GN-z11, a $M_\textrm{UV}$=-21.1 galaxy at $z$=11.1 (just 400 Myr after the Big Bang). With an estimated stellar mass of $\sim$10$^9$M$_\odot$, this galaxy is surprisingly ... 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 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
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
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 and galaxy formation simulation--VII. The sizes of high-redshift galaxiesAug 02 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
Time-Dependent Flow in Arrested States -- Transient BehaviourSep 02 2013The transient behaviour of highly concentrated colloidal liquids and dynamically arrested states (glasses) under time-dependent shear is reviewed. This includes both theoretical and experimental studies and comprises the macroscopic rheological behaviour ... More
Long-lived neighbors determine the rheological response of glassesDec 01 2016Glasses exhibit a liquid-like structure but a solid-like rheological response with plastic deformations only occurring beyond yielding. Thus, predicting the rheological behavior from the microscopic structure is difficult, but important for materials ... More
Magnetic interactions in the $S = 1/2$ square-lattice antiferromagnets Ba$_2$CuTeO$_6$ and Ba$_2$CuWO$_6$: parent phases of a possible spin liquidDec 13 2018The isostructural double perovskites Ba$_2$CuTeO$_6$ and Ba$_2$CuWO$_6$ are shown by theory and experiment to be frustrated square-lattice antiferromagnets with opposing dominant magnetic interactions. This is driven by differences in orbital hybridisation ... More
Stress-strain relations in bulk metallic glasses and colloidal dispersionsFeb 08 2013A comparison is made between the nonlinear rheological response of bulk metallic glass formers and of colloidal dispersions. Stress-strain curves measured after switch-on of constant deformation rates are analyzed quantitatively using a schematic model ... 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
Residual Stresses in GlassesFeb 16 2013The history dependence of the glasses formed from flow-melted steady states by a sudden cessation of the shear rate $\dot\gamma$ is studied in colloidal suspensions, by molecular dynamics simulations, and mode-coupling theory. In an ideal glass, stresses ... More
Psychological Frameworks for Persuasive Information and Communications TechnologiesAug 28 2018When developing devices to encourage positive change in users, social psychology can offer useful conceptual resources. This article outlines three major theories from the discipline and discusses their implications for designing persuasive technologies. ... More
Charge and orbital order in frustrated Pb3Mn7O15Jan 13 2012Mar 28 2012The candidate magnetoelectric Pb3Mn7O15 has a structure consisting of 1/3 filled Kagome layers linked by ribbons of edge-sharing octahedra in the stacking direction. Previous reports have indicated a complex hexagonal-orthorhombic structural transition ... More
Classical Control of Large-Scale Quantum ComputersMay 20 2014The accelerated development of quantum technology has reached a pivotal point. Early in 2014, several results were published demonstrating that several experimental technologies are now accurate enough to satisfy the requirements of fault-tolerant, error ... More
Two loop Kahler potential in beta-deformed N=4 SYM theoryMay 23 2008Aug 06 2008In N=2 superconformal field theories the Kahler potential is known to be tree level exact. The beta-deformation of N=4 SU(N) SYM reduces the amount of supersymmetry to N=1, allowing for non-trivial, superconformal loop corrections to the Kahler potential. ... More
The potential for super-Nyquist asteroseismology with TESSAug 11 2015The perfect 30-min cadence of the full-frame images from the Transiting Exoplanet Survey Satellite (TESS) will impose a hard Nyquist limit of 24 d$^{-1}$ ($\approx 278$ $\mu$Hz). This will be problematic for asteroseismology of stars with oscillation ... More
Coevality in Young Eclipsing BinariesApr 29 2017The ages of the components in very short period pre-main sequence (PMS) binaries are essential to an understanding of their formation. We considered a sample of 7 PMS eclipsing binaries (EBs) with ages 1 to 6.3 MY and component masses 0.2 to 1.4 Msun ... More
Contribution to Temporal Fault Tree Analysis without Modularization and Transformation into the State SpaceMay 18 2015Background: Fault tree analysis (FTA) is a well established method for qualitative as well as probabilistic reliability and safety analysis. As a Boolean model it does not support modelling of dynamic effects like sequence dependencies between fault events. ... More
Performing Quantum Computing Experiments in the CloudMay 18 2016Sep 01 2016Quantum computing technology has reached a second renaissance in the past five years. Increased interest from both the private and public sector combined with extraordinary theoretical and experimental progress has solidified this technology as a major ... More
An examination of some characteristics of Kepler Short and Long Cadence DataJan 30 2012A close comparison of Kepler short- and long-cadence data released prior to 2011 Nov 1 has shown some subtle differences that make the short-cadence data superior to their long-cadence counterparts. The inevitable results of a faster sampling rate are ... More
Fast simulation of stabilizer circuits using a graph state representationApr 15 2005Jan 03 2006According to the Gottesman-Knill theorem, a class of quantum circuits, namely the so-called stabilizer circuits, can be simulated efficiently on a classical computer. We introduce a new algorithm for this task, which is based on the graph-state formalism. ... More
Further Wolf-Rayet stars in the starburst cluster Westerlund 1Mar 14 2005Mar 21 2005We present new low and intermediate-resolution spectroscopic observations of the Wolf Rayet (WR) star population in the massive starburst cluster Westerlund 1. Finding charts are presented for five new WRs - four WNL and one WCL - raising the current ... More
A newly identified Luminous Blue Variable in the galactic starburst cluster Westerlund 1Dec 02 2003We present observations of the massive transitional star W243 in Westerlund 1. We find an apparent spectral type of early-mid A from our data, in contrast to an earlier classification of B2I, made from data obtained in 1981. The concurrent development ... More
Scalable Similarity Search for Molecular DescriptorsNov 30 2016Similarity search over chemical compound databases is a fundamental task in the discovery and design of novel drug-like molecules. Such databases often encode molecules as non-negative integer vectors, called molecular descriptors, which represent rich ... More
A General Approach to Regularizing Inverse Problems with Regional Data using Slepian WaveletsAug 15 2017Slepian functions are orthogonal function systems that live on subdomains (for example, geographical regions on the Earth's surface, or bandlimited portions of the entire spectrum). They have been firmly established as a useful tool for the synthesis ... More
D-modules on rigid analytic spaces II: Kashiwara's equivalenceFeb 04 2015We prove that the category of co-admissible D-cap-modules on a smooth rigid analytic space supported on a closed smooth subvariety is naturally equivalent to the category of co-admissible D-cap-modules on the subvariety, and use this result to construct ... More
Overview of Swallow --- A Scalable 480-core System for Investigating the Performance and Energy Efficiency of Many-core Applications and Operating SystemsApr 23 2015We present Swallow, a scalable many-core architecture, with a current configuration of 480 x 32-bit processors. Swallow is an open-source architecture, designed from the ground up to deliver scalable increases in usable computational power to allow experimentation ... More
Scalar and vector Slepian functions, spherical signal estimation and spectral analysisJun 13 2013It is a well-known fact that mathematical functions that are timelimited (or spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the finite precision of measurement and computation unavoidably bandlimits our observation and modeling ... More
Spatiospectral concentration of vector fields on a sphereJun 13 2013We construct spherical vector bases that are bandlimited and spatially concentrated, or, alternatively, spacelimited and spectrally concentrated, suitable for the analysis and representation of real-valued vector fields on the surface of the unit sphere, ... More
Fixed Block Compression Boosting in FM-IndexesApr 19 2011A compressed full-text self-index occupies space close to that of the compressed text and simultaneously allows fast pattern matching and random access to the underlying text. Among the best compressed self-indexes, in theory and in practice, are several ... More
Gaia's view of the $λ$ Boo star puzzleDec 05 2016The evolutionary status of the chemically peculiar class of $\lambda$ Boo stars has been intensely debated. It is now agreed that the $\lambda$ Boo phenomenon affects A stars of all ages, from star formation to the terminal age main sequence, but the ... More
O VI Observations of the Onset of Convection Zones in Main-Sequence A StarsMay 29 2008If magnetic activity in outer stellar atmospheres is due to an interplay between rotation and subsurface convection, as is generally presumed, then one would not expect to observe indicators of activity in stars with T_eff > 8300 K. Any X-ray or ultraviolet ... More
Generating of an electric potential on the Moon by Cosmic rays and Solar Wind?Aug 12 2010We investigate the possibility that the Moon develops an electric potential originating from the impinging particles on the Moon from cosmic rays and solar wind. The investigation includes all experimental data of the flux of charged particle for energies ... More
Trajectory Clustering, Modelling, and Selection with the Focus on Airspace ProtectionMar 30 2016Take-off and landing are the periods of a flight where aircraft are most vulnerable to a ground based rocket attack by terrorists. While aircraft approach and depart from airports on pre-defined flight paths, there is a degree of uncertainty in the trajectory ... More
Moebius energy of thick knotsAug 30 2001The Moebius energy of a knot is an energy functional for smooth curves based on an idea of self-repelling. If a knot has a thick tubular neighborhood, we would intuitively expect the energy to be low. In this paper, we give explicit bounds for energy ... More
Potential-field estimation from satellite data using scalar and vector Slepian functionsJun 27 2013In the last few decades a series of increasingly sophisticated satellite missions has brought us gravity and magnetometry data of ever improving quality. To make optimal use of this rich source of information on the structure of Earth and other celestial ... More
Effective three-body interactions via photon-assisted tunneling in an optical latticeNov 07 2013We present a simple, experimentally realizable method to make coherent three-body interactions dominate the physics of an ultracold lattice gas. Our scheme employs either lattice modulation or laser-induced tunneling to reduce or turn off two-body interactions ... More
Deriving the orbital properties of pulsators in binary systems through their light arrival time delaysApr 20 2015We present the latest developments to the phase modulation method for finding binaries among pulsating stars. We demonstrate how the orbital elements of a pulsating binary star can be obtained analytically, that is, without converting time delays to radial ... More
Disentangling Mass and Mixing HierarchiesJun 30 2015Oct 23 2015We present a fully perturbative mechanism that naturally generates mass hierarchies for the Standard Model (SM) fermions in a flavor-blind sector. The dynamics generating the mass hierarchies can therefore be independent from the source of flavor violation, ... More
A hidden population of Wolf-Rayet stars in the massive galactic cluster Westerlund 1Nov 12 2002We report the discovery of a hitherto undetected population of Wolf-Rayet stars in the young galactic open cluster Westerlund 1. Optical spectroscopy of the cluster identified 11 such objects; provisional classification suggests that 6 are nitrogen rich ... More
A Specification Format and a Verification Method of Fault-Tolerant Quantum CircuitsDec 28 2017Quantum computations are expressed in general as quantum circuits, which are specified by ordered lists of quantum gates. The resulting specifications are used during the optimisation and execution of the expressed computations. However, the specification ... More
Range Predecessor and Lempel-Ziv ParsingJul 25 2015The Lempel-Ziv parsing of a string (LZ77 for short) is one of the most important and widely-used algorithmic tools in data compression and string processing. We show that the Lempel-Ziv parsing of a string of length $n$ on an alphabet of size $\sigma$ ... More
Entanglement of Formation for Gaussian StatesAug 12 2008The entanglement of formation (EOF) is computed for arbitrary two-mode Gaussian states. Apart from a conjecture, our analysis rests on two main ingredients. The first is a four-parameter canonical form we develop for the covariance matrix, one of these ... More
Behavioural PrototypesSep 03 2016We sketch a simple language of concurrent objects which explores the design space between type systems and continuous testing. In our language, programs are collections of communicating automata checked automatically for multiparty compatibility. This ... More
An introduction to Fault-tolerant Quantum ComputingAug 15 2015In this paper we provide a basic introduction of the core ideas and theories surrounding fault-tolerant quantum computation. These concepts underly the theoretical framework of large-scale quantum computation and communications and are the driving force ... More
The very rich massive post-main-sequence star population of the open cluster Westerlund 1Aug 23 2002We report the discovery of a population of Wolf-Rayet stars in the young Galactic open cluster Westerlund 1. In an incomplete shallow spectroscopic survey, we find six nitrogen-rich (WN) and five carbon-rich (WC) WR stars. We also confirm the presence ... More
Nonexistence of solutions in $(0,1)$ for K-P-P-type equations for all $d\ge 1$Sep 16 2005Consider the KPP-type equation of the form $\Delta u+f(u)=0$, where $f:[0,1] \to \mathbb R_{+}$ is a concave function. We prove for arbitrary dimensions that there is no solution bounded in $(0,1)$. The significance of this result from the point of view ... More
Searching and Indexing Genomic Databases via KernelizationDec 04 2014The rapid advance of DNA sequencing technologies has yielded databases of thousands of genomes. To search and index these databases effectively, it is important that we take advantage of the similarity between those genomes. Several authors have recently ... More
High-Performance Code Generation though Fusion and VectorizationOct 24 2017We present a technique for automatically transforming kernel-based computations in disparate, nested loops into a fused, vectorized form that can reduce intermediate storage needs and lead to improved performance on contemporary hardware. We introduce ... More
Crossed products by twisted partial actions and graded algebrasJun 24 2008For a twisted partial action \Theta of a group G on an (associative non-necessarily unital) algebra A over a commutative unital ring k, the crossed product A X_\Theta G is proved to be associative. Given a G-graded k-algebra B = \oplus_{g\in G}\B_g with ... More
Vortex Chains in Anisotropic SuperconductorsJul 01 2005High-T_c superconductors in small magnetic fields directed away from the crystal symmetry axes have been found to exhibit inhomogeneous chains of flux lines (vortices), in contrast to the usual regular triangular flux-line lattice. We review the experimental ... More
Lempel-Ziv Parsing in External MemoryJul 04 2013For decades, computing the LZ factorization (or LZ77 parsing) of a string has been a requisite and computationally intensive step in many diverse applications, including text indexing and data compression. Many algorithms for LZ77 parsing have been discovered ... More
Session Types as Generic Process TypesAug 07 2014Behavioural type systems ensure more than the usual safety guarantees of static analysis. They are based on the idea of "types-as-processes", providing dedicated type algebras for particular properties, ranging from protocol compatibility to race-freedom, ... More
Observational constraints on the X-ray Bright supergiant B[e] stars LHA 115-S18 \& LHA 120-S 134Mar 01 2016We present the preliminary results of an ongoing series of spectroscopic observations of the Small Magellanic Cloud star LHA 115-S 18 (S18), which has demonstrated extreme photospheric and spectroscopic variability that, in some respects, is reminiscent ... More
Systems-level approach to uncovering diffusive states and their transitions from single particle trajectoriesAug 04 2016The stochastic motions of a diffusing particle contain information concerning the particle's interactions with binding partners and with its local environment. However, accurate determination of the underlying diffusive properties, beyond normal diffusion, ... More
Lattice Surgery Translation for Quantum ComputationAug 18 2016Aug 29 2016In this paper we outline a method for a compiler to translate any non fault tolerant quantum circuit to the geometric representation of the lattice surgery error-correcting code using inherent merge and split operations. Since the efficiency of state ... More
Science with the Australian Square Kilometre Array Pathfinder (ASKAP)Mar 24 2009The future of cm and m-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA ... More
Chi-square simulation of the CIR process and the Heston modelFeb 29 2008Jul 02 2012The transition probability of a Cox-Ingersoll-Ross process can be represented by a non-central chi-square density. First we prove a new representation for the central chi-square density based on sums of powers of generalized Gaussian random variables. ... More
Efficient almost-exact Levy area samplingJul 01 2011Jan 20 2014We present a new method for sampling the Levy area for a two-dimensional Wiener process conditioned on its endpoints. An efficient sampler for the Levy area is required to implement a strong Milstein numerical scheme to approximate the solution of a stochastic ... More
An introduction to SDE simulationApr 05 2010We outline the basic ideas and techniques underpinning the simulation of stochastic differential equations. In particular we focus on strong simulation and its context. We also provide illustratory examples and sample matlab algorithms for the reader ... More
Time versus Hardware: Reducing Qubit Counts with a (Surface Code) Data BusFeb 21 2019A data bus, for reducing the qubit counts within quantum computations (protected by surface codes), is introduced. For general computations an automated trade-off analysis (software tool and source code are open sourced and available online) is performed ... More
Extending the Reach of QKD Using RelaysMar 03 2012One of the obstacles to deployment of QKD solutions has been the distance limitation. Solutions using relays have been proposed but these rely on link-by-link key establishment. We present a new technique to extend the distance of a quantum key distribution ... More
Mass Dependence of Quantum Energy Inequality BoundsFeb 21 2007In a recent paper [J. Math. Phys. 47 082303 (2006)], Quantum Energy Inequalities were used to place simple geometrical bounds on the energy densities of quantum fields in Minkowskian spacetime regions. Here, we refine this analysis for massive fields, ... More
New low-mass members of the Octans stellar association and an updated 30-40 Myr lithium ageNov 20 2014The Octans association is one of several young stellar moving groups recently discovered in the Solar neighbourhood, and hence a valuable laboratory for studies of stellar, circumstellar disc and planetary evolution. However, a lack of low-mass members ... More
Gorenstein rings call the tuneJul 16 2004Hochster's Monomial Conjecture and Canonical Element Conjecture date back some thirty resp. twenty years. They concern all noetherian commutative local rings, and were proved by their originator right away in equal characteristic. Thanks to recent important ... More
Towards a complete census of young stars in the solar neighbourhood with SkyMapperJun 10 2008In this contribution we outline plans for identifying and characterising numerous young, low-mass stars within 150 pc of the Sun using the new SkyMapper telescope and Southern Sky Survey. We aim to learn more about the star formation history of the solar ... More
The covariance of cosmic shear correlation functions and cosmological parameter estimates using redshift informationSep 01 2003Jan 14 2004Cosmological weak lensing by the large scale structure of the Universe, cosmic shear, is coming of age as a powerful probe of the parameters describing the cosmological model and matter power spectrum. It complements CMB studies, by breaking degeneracies ... More
Scalable data abstractions for distributed parallel computationsOct 03 2012The ability to express a program as a hierarchical composition of parts is an essential tool in managing the complexity of software and a key abstraction this provides is to separate the representation of data from the computation. Many current parallel ... More
Plausible fluorescent Ly-alpha emitters around the z=3.1 QSO0420-388Nov 14 2006Feb 28 2007We report the results of a survey for fluorescent Ly-alpha emission carried out in the field surrounding the z=3.1 quasar QSO0420-388 using the FORS2 instrument on the VLT. We first review the properties expected for fluorescent Ly-alpha emitters, compared ... More
A bridge to lower overhead quantum computationSep 04 2012Apr 09 2013Two primary challenges stand in the way of practical large-scale quantum computation, namely achieving sufficiently low error rate quantum gates and implementing interesting quantum algorithms with a physically reasonable number of qubits. In this work ... More
CO-dark gas and molecular filaments in Milky Way-type galaxies - II: The temperature distribution of the gasJul 27 2016We investigate the temperature distribution of CO-dark molecular hydrogen (H2) in a series of disk galaxies simulated using the AREPO moving-mesh code. In conditions similar to those in the Milky Way, we find that H2 has a flat temperature distribution ... More
Systemization of Pluggable Transports for Censorship ResistanceDec 23 2014Jul 29 2016An increasing number of countries implement Internet censorship at different scales and for a variety of reasons. In particular, the link between the censored client and entry point to the uncensored network is a frequent target of censorship due to the ... More
Diphotons from an Electroweak Triplet-SingletMar 29 2016The neutral component of a real pseudoscalar electroweak (EW) triplet can produce a diphoton excess at 750 GeV, if it is somewhat mixed with an EW singlet pseudoscalar. This triplet-singlet mixing allows for greater freedom in the diboson branching ratios ... More
New Algorithms on Wavelet Trees and Applications to Information RetrievalNov 19 2010Wavelet trees are widely used in the representation of sequences, permutations, text collections, binary relations, discrete points, and other succinct data structures. We show, however, that this still falls short of exploiting all of the virtues of ... More
String Inference from the LCP ArrayJun 14 2016The suffix array is often augmented with the longest common prefix (LCP) array which is, in essence, a representation of the suffix tree shape. We consider the problem of inferring a string from an LCP array, i.e., determining whether a given array of ... More
Hydro-mechanical network modelling of particulate compositesJul 26 2017Oct 12 2017Differential shrinkage in particulate quasi-brittle materials causes microcracking which reduces durability in these materials by increasing their mass transport properties. A hydro-mechanical three-dimensional periodic network approach was used to investigate ... More
m-Bonsai: a Practical Compact Dynamic TrieApr 19 2017We consider the problem of implementing a space-efficient dynamic trie, with an emphasis on good practical performance. For a trie with $n$ nodes with an alphabet of size $\sigma$, the information-theoretic lower bound is $n \log \sigma + O(n)$ bits. ... More