Results for "Brett M. Morris"

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Robust Transiting Exoplanet Radii in the Presence of Starspots from Ingress and Egress DurationsJul 13 2018We typically measure the radii of transiting exoplanets from the transit depth, which is given by the ratio of cross-sectional areas of the planet and star. However, if a star has dark starspots (or bright regions) distributed throughout the transit chord, ... More
Are Starspots and Plages Co-Located on Active G and K Stars?Sep 12 2018We explore the connection between starspots and plages of three main-sequence stars by studying the chromospheric and photospheric activity over several rotation periods. We present simultaneous photometry and high-resolution ($R\sim 31,500$) spectroscopy ... More
astroplan: An Open Source Observation Planning Package in PythonDec 27 2017Jan 02 2018We present astroplan - an open source, open development, Astropy affiliated package for ground-based observation planning and scheduling in Python. astroplan is designed to provide efficient access to common observational quantities such as celestial ... More
Diffuser-assisted Photometric Follow-up Observations of the Neptune-sized Planets K2-28b and K2-100bJul 12 2018We present precision transit observations of the Neptune-sized planets K2-28b and K2-100b, using the Engineered Diffuser on the ARCTIC imager on the ARC 3.5m Telescope at Apache Point Observatory. K2-28b is a $R_{p} = 2.56 R_\oplus$ mini-Neptune transiting ... More
Extreme precision photometry from the ground with beam-shaping diffusers for K2, TESS and beyondAug 07 2018The Transiting Exoplanet Survey Satellite (TESS, launched early 2018) is expected to find a multitude of new transiting planet candidates around the nearest and brightest stars. Timely high-precision follow-up observations from the ground are essential ... More
astroquery: An Astronomical Web-Querying Package in PythonJan 14 2019astroquery is a collection of tools for requesting data from databases hosted on remote servers with interfaces exposed on the internet, including those with web pages but without formal application program interfaces (APIs). These tools are built on ... More
Towards Space-like Photometric Precision from the Ground with Beam-Shaping DiffusersOct 04 2017We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such ... More
Optimal Actuator Design for Semi-linear SystemsFeb 16 2018Oct 22 2018Actuator location and design are important choices in controller design for distributed parameter systems. Semi-linear partial differential equations model a wide spectrum of physical systems with distributed parameters. It is shown that under certain ... More
The Role of Professional Societies in STEM DiversityOct 26 2017The overall percentages of African American scientists indicate underrepresentation in most science, technology, engineering, and mathematics (STEM) disciplines and the percentages appear to be declining over the last three decades. We will share insights ... More
Molecular dynamic simulation of a homogeneous bcc -> hcp transitionMar 13 2001We have performed molecular dynamic simulations of a Martensitic bcc->hcp transformation in a homogeneous system. The system evolves into three Martensitic variants, sharing a common nearest neighbor vector along a bcc <111> direction, plus an fcc region. ... More
Optimal control of elliptic PDEs at pointsNov 18 2014We consider an elliptic optimal control problem where the objective functional contains evaluations of the state at a finite number of points. In particular, we use a fidelity term that encourages the state to take certain values at these points, which ... More
Affine nonexpansive operators, Attouch-Théra duality and the Douglas-Rachford algorithmMar 30 2016The Douglas-Rachford splitting algorithm was originally proposed in 1956 to solve a system of linear equations arising from the discretization of a partial differential equation. In 1979, Lions and Mercier brought forward a very powerful extension of ... More
Optimal control of elliptic PDEs on surfaces of codimension 1Nov 18 2014We consider an elliptic optimal control problem where the objective functional contains an integral along a surface of codimension 1, also known as a hypersurface. In particular, we use a fidelity term that encourages the state to take certain values ... More
Stability and Well-posedness of a Nonlinear Railway Track ModelMar 08 2018Jul 03 2018Railway tracks rest on a foundation known for exhibiting nonlinear viscoelastic behavior. Railway track deflections are modeled by a semilinear partial differential equation. This paper studies the stability of solutions to this equation in presence of ... More
Monte-Carlo simulation of ELT scale multi-object adaptive optics deformable mirror requirements and tolerancesJul 17 2013Multi-object adaptive optics (MOAO) has been demonstrated by the CANARY instrument on the William Herschel Telescope. However, for proposed MOAO systems on the next generation Extremely Large Telescopes, such as EAGLE, many challenges remain. Here we ... More
Constraining Stellar Photospheres as an Essential Step for Transmission Spectroscopy of Small ExoplanetsMar 14 2019Transmission spectra probe the atmospheres of transiting exoplanets, but these observations are also subject to signals introduced by magnetic active regions on host stars. Here we outline scientific opportunities in the next decade for providing useful ... More
Exploded FibrationsMay 16 2007Initiated by Gromov, the study of holomorphic curves in symplectic manifolds has been a powerfull tool in symplectic topology, however the moduli space of holomorphic curves is often very difficult to find. A common technique is to study the limiting ... More
Tropical gluing formulae for Gromov-Witten invariantsMar 16 2017We prove two tropical gluing formulae for Gromov-Witten invariants of exploded manifolds, useful for calculating Gromov-Witten invariants of a symplectic manifold using a normal-crossing degeneration. The first formula generalizes the symplectic-sum formula ... More
Field Theories Without a Holographic DualJun 08 2016Oct 24 2016In applying the gauge-gravity duality to the quark-gluon plasma, one models the plasma using a particular kind of field theory with specified values of the temperature, magnetic field, and so forth. One then assumes that the bulk, an asymptotically AdS ... More
A short proof of backward uniqueness for some geometric evolution equationsJan 05 2015We give a simple, direct proof of the backward uniqueness of solutions to a class of second-order geometric evolution equations including the Ricci and cross-curvature flows. The proof, based on a classical argument of Agmon-Nirenberg, uses the logarithmic ... More
An energy approach to the problem of uniqueness for the Ricci flowJun 14 2012We revisit the problem of uniqueness for the Ricci flow and give a short, direct proof, based on the consideration of a simple energy quantity, of Hamilton/Chen-Zhu's theorem on the uniqueness of complete solutions of uniformly bounded curvature. With ... More
Non-uniform covering array with symmetric forbidden edge constraintsJan 08 2019It has been conjectured that whenever an optimal covering array exists there is also a uniform covering array with the same parameters and this is true for all known optimal covering arrays. When used as a test suite, the application context may have ... More
Kepler's Optical Secondary Eclipse of HAT-P-7b and Probable Detection of Planet-Induced Stellar Gravity DarkeningJan 18 2013We present observations spanning 355 orbital phases of HAT-P-7 observed by Kepler from May 2009 to March 2011 (Q1-9). We find a shallower secondary eclipse depth than initially announced, consistent with a low optical albedo and detection of nearly exclusively ... More
Holomorphic curves in exploded manifolds: virtual fundamental classDec 17 2015This paper defines Gromov-Witten invariants of exploded manifolds using embedded Kuranishi structures, constructed in arXiv:1301.4748. The technical heart of this paper is a construction of a virtual fundamental class $[\mathcal K]$ of any Kuranishi category ... More
Gluing formula for Gromov-Witten invariants in a triple productNov 03 2015We present a gluing formula for Gromov-Witten invariants in the case of a triple product. This gluing formula is a simple case of a much more general gluing formula proved and stated using exploded manifolds. We present this simple case because it is ... More
A local version of Bando's theorem on the real-analyticity of solutions to the Ricci flowNov 02 2011It is a theorem of S. Bando that if $g(t)$ is a solution to the Ricci flow on a compact manifold $M$, then $(M, g(t))$ is real-analytic for each $t >0$. In this note, we extend his result to smooth solutions on open domains $U\subset M$.
The Motion of Water Masers in the Pre-Planetary Nebula IRAS 16342-3814Oct 07 2008We present high angular resolution observations, using the Very Long Baseline Array (VLBA) of the NRAO, of the high-velocity water masers toward the "water-fountain" pre-planetary nebula, IRAS 16342-3814. The detailed structure of the water masers appears ... More
An Interesting IdentityMar 13 2015This purpose of this paper is to note an interesting identity derived from an integral in Gradshteyn and Ryzhik using techniques from George Boros'(deceased) Ph.D thesis. The idenity equates a sum to a product by evaluating an integral in two different ... More
Large Starspot Groups on HAT-P-11 in Activity Cycle 1Jan 30 2018HAT-P-11 is a planet-hosting K4V star in the Kepler field, with an activity cycle that bear similarities to the Sun's. The chromospheric activity of HAT-P-11 indicates that a new activity cycle is beginning. We report ground-based observations with holographic ... More
A VLA H92alpha Study of the Arched Filament Complex Near the Galactic CenterFeb 08 2001The VLA has been used at 8.3 GHz in the DnC and CnB array configurations to carry out an H92alpha recombination line study (at 8.3 GHz) of the ionized gas in the Arched Filaments H II complex, which defines the western edge of the Galactic center Radio ... More
Non-monotonic flow curves of shear thickening suspensionsDec 15 2014May 11 2015The discontinuous shear thickening (DST) of dense suspensions is a remarkable phenomenon in which the viscosity can increase by several orders of magnitude at a critical shear rate. It has the appearance of a first order phase transition between two hypothetical ... More
Shear thickening, frictionless and frictional rheologies in non-Brownian suspensionsMar 26 2014Sep 24 2014Particles suspended in a Newtonian fluid raise the viscosity and also generally give rise to a shear-rate dependent rheology. In particular, pronounced shear thickening may be observed at large solid volume fractions. In a recent article (R. Seto, R. ... More
The Molecular Counterpart of the Galactic Center Arched Filament HII Complex: OVRO Observations of the CS(2-1) LineAug 16 2002The Owens Valley Radio Observatory (OVRO) millimeter array was used to make observations of the CS(2-1) line (at 97.981 GHz) arising from the G0.07+0.04 region of the ``-30 km/s'' molecular cloud near the Galactic center with a spatial resolution of ~8". ... More
Potential Science for the OASIS Integral Field Spectrograph with Laser Guide Star Adaptive OpticsSep 15 2005We review the science case for the Laser Guide Star system being built for the William Herschel Telescope (WHT) on La Palma. When used in combination with the NAOMI Adaptive Optics system and the OASIS visible-wavelength Integral Field Spectrograph, we ... More
Particle-in-cell study of the ion-to-electron sheath transitionApr 27 2016The form of a sheath near a small electrode, with bias changing from below to above the plasma potential is studied using 2D particle-in-cell (PIC) simulations. Five cases are studied: (A) an electrode biased more than the electron temperature ($T_e/e$) ... More
Productive Dialog During Collaborative Problem SolvingJun 03 2008Collaboration is an important problem-solving skill; however, novice collaboration generally benefits from some kind of support. One possibility for supporting productive conversations between collaborators is to encourage pairs of students to provide ... More
A Thermodynamic Model of Electric-Field-Induced Pattern Formation in Binary Dielectric FluidsNov 21 2002An electric-field-induced phase transition and pattern formation in a binary dielectric fluid layer are studied using a coarse-grained free energy functional. The electrostatic part of the free energy is a nonlinear functional of the dielectric function, ... More
Searching for Trojan Asteroids in the HD 209458 System: Space-based MOST Photometry and Dynamical ModelingMay 18 2010We have searched Microvariability and Oscillations of STars (MOST) satellite photometry obtained in 2004, 2005, and 2007 of the solar-type star HD 209458 for Trojan asteroid swarms dynamically coupled with the system's transiting "hot Jupiter" HD 209458b. ... More
Zero-temperature Glauber dynamics on Z^dSep 02 2008Nov 26 2009We study zero-temperature Glauber dynamics on \Z^d, which is a dynamic version of the Ising model of ferromagnetism. Spins are initially chosen according to a Bernoulli distribution with density p, and then the states are continuously (and randomly) updated ... More
A New Continuum Formulation for Materials--Part I. The Equations of Motion for a Single-Component FluidSep 17 2013Jan 24 2017The continuum equations of fluid mechanics are rederived with the intention of keeping certain mechanical and thermodynamic concepts separate. A new "mechanical" mass density is created to be used in computing inertial quantities, whereas the actual mass ... More
Elementary proof that $\mathbb Z_p^4$ is a DCI-groupMar 18 2014A finite group $R$ is a DCI-group if, whenever $S$ and $T$ are subsets of $R$ with the Cayley graphs ${\rm Cay}(R,S)$ and ${\rm Cay}(R,T)$ isomorphic, there exists an automorphism $\varphi$ of $R$ with $S^\varphi=T$. Elementary abelian groups of order ... More
Automorphism groups of circulant graphs -- a surveyNov 13 2004A circulant (di)graph is a (di)graph on n vertices that admits a cyclic automorphism of order n. This paper provides a survey of the work that has been done on finding the automorphism groups of circulant (di)graphs, including the generalisation in which ... More
The mixing time of the Thorp shuffleJul 15 2005The Thorp shuffle is defined as follows. Cut the deck into two equal piles. Drop the first card from the left pile or the right pile according to the outcome of a fair coin flip; then drop from the other pile. Continue this way until both piles are empty. ... More
Comparison of discrete and continuum Liouville first passage percolationApr 19 2019Discrete and continuum Liouville first passage percolation (DLFPP, LFPP) are two approximations of the conjectural $\gamma$-Liouville quantum gravity (LQG) metric, obtained by exponentiating the discrete Gaussian free field (GFF) and the circle average ... More
Nonstationary open dynamical systemsAug 16 2018This paper studies nonstationary open dynamical systems from the statistical viewpoint. By open, we mean that trajectories may escape through holes in the phase space. By nonstationary, we mean that the dynamical model itself (as well as the holes) may ... More
Efficient Eligibility Traces for Deep Reinforcement LearningOct 23 2018Eligibility traces are an effective technique to accelerate reinforcement learning by smoothly assigning credit to recently visited states. However, their online implementation is incompatible with modern deep reinforcement learning algorithms, which ... More
Classification of Reconfiguration Graphs of Shortest Path Graphs With No Induced $4$-cyclesAug 28 2018For any graph $G$ with $a,b\in V(G)$, a shortest path reconfiguration graph can be formed with respect to $a$ and $b$; we denote such a graph as $S(G,a,b)$. The vertex set of $S(G,a,b)$ is the set of all shortest paths from $a$ to $b$ in $G$ while two ... More
To stay discovered: On tournament mean score sequences and the Bradley--Terry modelNov 16 2018On being told that a piece of work he thought was his discovery had duplicated an earlier mathematician's work, Larry Shepp once replied "Yes, but when {\em I} discovered it, it {\em stayed} discovered". In this spirit we give discussion and probabilistic ... More
A Note about Stabilization in $A_\R(\D)$Jan 31 2007It is shown that for $A_\R(\D)$ functions $f_1$ and $f_2$ with $$ \inf_{z\in\bar{\D}}(\abs{f_1(z)}+\abs{f_2(z)})\geq\delta>0 $$ and $f_1$ being positive on real zeros of $f_2$ then there exists $A_\R(\D)$ functions $g_2$ and $g_1,g_1^{-1}$ with and $$ ... More
Stabilization in $H^\infty_{\mathbb{R}}(\mathbb{D})$Sep 09 2008Oct 18 2010In this paper we prove the following theorem: Suppose that $f_1,f_2\in H^\infty_\R(\D)$, with $\norm{f_1}_\infty,\norm{f_2}_{\infty}\leq 1$, with $$ \inf_{z\in\D}(\abs{f_1(z)}+\abs{f_2(z)})=\delta>0. $$ Assume for some $\epsilon>0$ and small, $f_1$ is ... More
Arithmetic aspects of the Burkhardt quartic threefoldMay 25 2017May 29 2018We show that the Burkhardt quartic threefold is rational over any field of characteristic distinct from 3. We compute its zeta function over finite fields. We realize one of its moduli interpretations explicitly by determining a model for the universal ... More
Nonstationary open dynamical systemsAug 16 2018May 14 2019This paper studies nonstationary open dynamical systems from the statistical viewpoint. By open, we mean that trajectories may escape through holes in the phase space. By nonstationary, we mean that the dynamical model itself (as well as the holes) may ... More
The properties of Ly-alpha emitting galaxies in hierarchical galaxy formation modelsAug 08 2005Oct 25 2005We present detailed predictions for the properties of Ly-alpha-emitting galaxies in the framework of the Lambda-CDM cosmology, calculated using the semi-analytical galaxy formation model GALFORM. We explore a model which assumes a top-heavy IMF in starbursts, ... More
An evla and carma study of dusty disks and torii with large grains in dying starsJun 21 2011We report the results of a pilot multiwavelength survey in the radio continuum (X, Ka and Q bands, i.e., from 3.6 cm to 7 mm) carried out with the EVLA in order to confirm the presence of very large dust grains in dusty disks and torii around the central ... More
Thermodynamically Stable Blue PhasesJan 28 2011We show theoretically that flexoelectricity stabilizes blue phases in chiral liquid crystals. Induced internal polarization reduces the elastic energy cost of splay and bend deformations surrounding singular lines in the director field. The energy of ... More
High Proper Motion Stars in the Vicinity of Sgr A*: Evidence for a Supermassive Black Hole at the Center of Our GalaxyJul 20 1998Jul 21 1998Over a two year period (1995-1997), we have conducted a diffraction-limited imaging study at 2.2 microns of the inner 6"x6" of the Galaxy's central stellar cluster using the Keck 10-m telescope. The K band images obtained reveal a large population of ... More
Probing the Mass and Structure of the Ring Nebula in Lyra with SOFIA/GREAT Observations of the [CII] 158 micron lineMar 28 2012We have obtained new velocity-resolved spectra of the [CII] 158 micron line towards the Ring Nebula in Lyra (NGC 6720), one of the best-studied planetary nebulae, in order to probe its controversial 3-dimensional structure and to estimate the mass of ... More
Science Requirements and Trade-offs for the MOSAIC Instrument for the European ELTAug 23 2016Building on the comprehensive White Paper on the scientific case for multi-object spectroscopy on the European ELT, we present the top-level instrument requirements that are being used in the Phase A design study of the MOSAIC concept. The assembled cases ... More
Detection of Interstellar HC$_5$O in TMC-1 with the Green Bank TelescopeJun 29 2017We report the detection of the carbon-chain radical HC$_5$O for the first time in the interstellar medium toward the dark cloud TMC-1 using the 100 m Green Bank Telescope. We observe four hyperfine components of this radical in the $J = 17/2 \rightarrow ... More
Stellar Spin-Orbit Alignment for Kepler-9, a Multi-transiting Planetary system with Two Outer Planets Near 2:1 ResonanceDec 18 2017We present spectroscopic measurements of the Rossiter-McLaughlin effect for the planet b of Kepler-9 multi-transiting planet system. The resulting sky-projected spin-orbit angle is $\lambda=-13^{\circ} \pm 16^{\circ}$, which favors an aligned system and ... More
Pushing Automated Abundance Derivations Into the Cool Star Regime: A Test Using Three G and Two K Stars in PraesepeDec 07 2018We present the results of an abundance analysis of three G and two K dwarfs in the Praesepe open cluster based on high-resolution, moderate signal-to-noise-ratio spectra obtained with the ARC 3.5-m Telescope at Apache Point Observatory. Using a Principle ... More
Remarks on Matsumoto and Amano's normal form for single-qubit Clifford+T operatorsDec 23 2013Matsumoto and Amano (2008) showed that every single-qubit Clifford+T operator can be uniquely written of a particular form, which we call the Matsumoto-Amano normal form. In this mostly expository paper, we give a detailed and streamlined presentation ... More
Ricci flow and the holonomy groupMay 18 2011We prove that the restricted holonomy group of a complete smooth solution to the Ricci flow of uniformly bounded curvature cannot spontaneously contract in finite time; it follows, then, from an earlier result of Hamilton that the holonomy group is exactly ... More
Thresholds for contagious sets in random graphsNov 30 2016For fixed $r\geq 2$, we consider bootstrap percolation with threshold $r$ on the Erd\H{o}s-R\'enyi graph ${\cal G}_{n,p}$. We identify a threshold for $p$ above which there is with high probability a set of size $r$ which can infect the entire graph. ... More
An Infrared Study of the Dust Properties and Geometry of the Arched Filaments HII Region with SOFIA/FORCASTFeb 14 2017Massive stellar clusters provide radiation ($\mathrm{\sim 10^7-10^8~L_{\odot}}$) and winds ($\mathrm{\sim 1000~km/s}$) that act to heat dust and shape their surrounding environment. In this paper, the Arched Filaments in the Galactic center were studied ... More
HD 202772A B: A Transiting Hot Jupiter Around A Bright, Mildly Evolved Star In A Visual Binary Discovered By TessOct 04 2018We report the first confirmation of a hot Jupiter discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HD 202772A b. The transit signal was detected in the data from TESS Sector 1, and was confirmed to be of planetary origin through ... More
Predictive modelling of training loads and injury in Australian footballJun 14 2017To investigate whether training load monitoring data could be used to predict injuries in elite Australian football players, data were collected from elite athletes over 3 seasons at an Australian football club. Loads were quantified using GPS devices, ... More
Heterogeneity in $^{12}$CO/$^{13}$CO Ratios Toward Solar-Type Young Stellar ObjectsSep 21 2015This study reports an unusual heterogeneity in [$^{12}$C$^{16}$O]/[$^{13}$C$^{16}$O] abundance ratios of carbon monoxide observed in the gas phase toward seven ~ solar-mass YSOs and three dense foreground clouds in the nearby star-forming regions, Ophiuchus, ... More
Solar Atmospheric Magnetic Energy Coupling: Broad Plasma Conditions and Spectrum RegimesJan 12 2016Sep 20 2016Solar variability investigations that include magnetic energy coupling are paramount to solving many key solar/stellar physics problems, particularly for understanding the temporal variability of magnetic energy redistribution and heating processes. Using ... More
Molecular and ionized gas kinematics in the GC Radio ArcSep 30 2016We present NH3 and H64a+H63a VLA observations of the Radio Arc region, including the M0.20-0.033 and G0.10-0.08 molecular clouds. These observations suggest the two velocity components of M0.20-0.033 are physically connected in the south. Additional ATCA ... More
Radio Detections of Stellar Winds from the Pistol Star and Other Stars in the Galactic Center Quintuplet ClusterJul 13 1999VLA images of the Sickle and Pistol H II regions near the Galactic center at 3.6 and 6 cm reveal six point sources in the region where the dense Quintuplet stellar cluster is located. The spectral indices of five of these sources between 6 cm and 3.6 ... More
Nuclear Structure from the In-Medium Similarity Renormalization GroupMay 23 2018Efforts to describe nuclear structure and dynamics from first principles have advanced significantly in recent years. Exact methods for light nuclei are now able to include continuum degrees of freedom and treat structure and reactions on the same footing, ... More
Verifying Spent Fuel Containers Before Deep Geological Storage with Cosmic Ray MuonsMay 09 2019International nuclear safeguards inspectors do not have a method to verify the contents of sealed storage casks containing spent reactor fuel. The heavy shielding that is used to limit radiation emission attenuates and scatters photons and neutrons emitted ... More
$L^q$-spectra of self-affine measures: closed forms, counterexamples, and split binomial sumsNov 08 2018We study $L^q$-spectra of planar self-affine measures generated by diagonal systems with an emphasis on providing closed form expressions. We answer a question posed by Fraser in 2016 in the negative by proving that a certain natural closed form expression ... More
Hamiltonian cycles in (2,3,c)-circulant digraphsSep 30 2006Let D be the circulant digraph with n vertices and connection set {2,3,c}. (Assume D is loopless and has outdegree 3.) Work of S.C.Locke and D.Witte implies that if n is a multiple of 6, c is either (n/2) + 2 or (n/2) + 3, and c is even, then D does not ... More
The Bass and Topological Stable Ranks of $H^\infty_\R(\D)$ and $A_\R(\D)$Jun 18 2008In this note we prove that the Bass stable rank of $H^\infty_\R(\D)$ is two. This establishes the validity of a conjecture by S. Treil. We accomplish this in two different ways, one by giving a direct proof, and the other, by first showing that the topological ... More
Weighted estimates for the Bergman projection on the Hartogs triangleApr 23 2019May 01 2019We apply modern techniques of dyadic harmonic analysis to obtain sharp estimates for the Bergman projection in weighted Bergman spaces. Our main theorem focuses on the Bergman projection on the Hartogs triangle. The estimates of the operator norm are ... More
Thin Sequences and Their Role in Model Spaces and Douglas AlgebrasOct 02 2014May 05 2015We study thin interpolating sequences $\{\lambda_n\}$ and their relationship to interpolation in the Hardy space $H^2$ and the model spaces $K_\Theta = H^2 \ominus \Theta H^2$, where $\Theta$ is an inner function. Our results, phrased in terms of the ... More
Thin SequencesAug 30 2015Oct 04 2015We look at thin interpolating sequences and the role they play in uniform algebras, Hardy spaces, and model spaces.
Some remarks about interpolating sequences in reproducing kernel Hilbert spacesSep 08 2011Apr 22 2013In this paper we study two separate problems on interpolation. We first give some new equivalences of Stout's Theorem on necessary and sufficient conditions for a sequence of points to be an interpolating sequence on a finite open Riemann surface. We ... More
Uncoverings on graphs and network reliabilityDec 14 2010Apr 13 2011We propose a network protocol similar to the $k$-tree protocol of Itai and Rodeh [{\em Inform.\ and Comput.}\ {\bf 79} (1988), 43--59]. To do this, we define an {\em $t$-uncovering-by-bases} for a connected graph $G$ to be a collection $\mathcal{U}$ of ... More
Probing the intra-group medium of a z = 0.28 galaxy groupJul 12 2016Apr 13 2017We present new MUSE observations of a galaxy group probed by a background quasar. The quasar sightline passes between multiple $z=0.28$ galaxies, whilst showing at the same redshift low ionised metal line species, including Ca II, Mg I, Mg II and Fe II. ... More
The Galactic Centre ChimneyApr 11 2019Evidence has increasingly mounted in recent decades that outflows of matter and energy from the central parsecs of our Galaxy have shaped the observed structure of the Milky Way on a variety of larger scales. On scales of ~15 pc, the Galactic centre has ... More
Weak Factorizations of the Hardy space $H^1(\mathbb{R}^n)$ in terms of Multilinear Riesz TransformsMar 08 2016Mar 19 2016This paper provides a constructive proof of the weak factorizations of the classical Hardy space $H^1(\mathbb{R}^n)$ in terms of multilinear Riesz transforms. As a direct application, we obtain a new proof of the characterization of ${\rm BMO}(\mathbb{R}^n)$ ... More
Reply to comment on: "An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre"Apr 11 2019In response to the comment posted by Nakashima et al. (arXiv:1903.1176), regarding prior claims for the features that we referred to as the Galactic Center Chimneys (2019, Nature, 567, 347), we point out the following: 1) The Nakashima et al. 2019 paper ... More
A search for transits of GJ 581\lowercase{e} and characterization of the host star variability using MOST space telescope photometryNov 02 2012The GJ 581 system has been amply studied since its discovery in 2005: the number of known planets in the system has increased and their orbital parameters are among the most precisely determined for radial velocity detected exoplanets. We have acquired ... More
Isomorphisms of Cayley graphs on nilpotent groupsMar 06 2016Mar 11 2016Let S be a finite generating set of a torsion-free, nilpotent group G. We show that every automorphism of the Cayley graph Cay(G;S) is affine. (That is, every automorphism of the graph is obtained by composing a group automorphism with multiplication ... More
Global Brain Dynamics During Social Exclusion Predict Subsequent Behavioral ConformityOct 02 2017Individuals react differently to social experiences; for example, people who are more sensitive to negative social experiences, such as being excluded, may be more likely to adapt their behavior to fit in with others. We examined whether functional brain ... More
Science with an ngVLA: Observing the Effects of Chemistry on Exoplanets and Planet FormationOct 15 2018One of the primary mechanisms for inferring the dynamical history of planets in our Solar System and in exoplanetary systems is through observation of elemental ratios (i.e. C/O). The ability to effectively use these observations relies critically on ... More
An Apparent Precessing Helical Outflow from a Massive Evolved Star: Evidence for Binary InteractionDec 23 2015Jan 16 2016Massive, evolved stars play a crucial role in the metal-enrichment, dust budget, and energetics of the interstellar medium, however, the details of their evolution are uncertain because of their rarity and short lifetimes before exploding as supernovae. ... More
Perturbatively renormalizable quantum gravityApr 11 2018May 16 2018The Wilsonian renormalization group (RG) requires Euclidean signature. The conformal factor of the metric then has a wrong-sign kinetic term, which has a profound effect on its RG properties. In particular around the Gaussian fixed point, it supports ... More
Infinitely many nonsolvable groups whose Cayley graphs are hamiltonianJul 17 2015This note shows there are infinitely many finite groups G, such that every connected Cayley graph on G has a hamiltonian cycle, and G is not solvable. Specifically, for every prime p that is congruent to 1, modulo 30, we show there is a hamiltonian cycle ... More
A rapidly-converging lower bound for the joint spectral radius via multiplicative ergodic theoryJun 01 2009We use ergodic theory to prove a quantitative version of a theorem of M. A. Berger and Y. Wang, which relates the joint spectral radius of a set of matrices to the spectral radii of finite products of those matrices. The proof rests on a theorem asserting ... More
Cyclic $m$-cycle systems of complete graphs minus a 1-factorNov 13 2015In this paper, we provide necessary and sufficient conditions for the existence of a cyclic $m$-cycle system of $K_n-I$ when $m$ and $n$ are even and $m \mid n$.
A Radio Survey of Galactic Center CloudsDec 20 2013We present a survey of molecules in a sample of Galactic center molecular clouds using the Karl G. Jansky Very large Array, which includes M0.25+0.01, the clouds near Sgr A, and Sgr B2. The molecules detected are primarily NH3 and HC3N; in Sgr B2-N we ... More
MUSE searches for galaxies near very metal-poor gas clouds at z~3: new constraints for cold accretion modelsJul 13 2016Aug 03 2016We report on the search for galaxies in the proximity of two very metal-poor gas clouds at z~3 towards the quasar Q0956+122. With a 5-hour MUSE integration in a ~500x500 kpc^2 region centred at the quasar position, we achieve a >80% complete spectroscopic ... More
Super-Solar Metallicity Stars in the Galactic Center Nuclear Star Cluster: Unusual Sc, V, and Y AbundancesFeb 22 2018Mar 06 2018We present adaptive-optics assisted near-infrared high-spectral resolution observations of late-type giants in the nuclear star cluster of the Milky Way. The metallicity and elemental abundance measurements of these stars offer us an opportunity to understand ... More
Rolling G_2 ModuliAug 28 2003We study the time evolution of freely rolling moduli in the context of M-theory on a G_2 manifold. This free evolution approximates the correct dynamics of the system at sufficiently large values of the moduli when effects from non-perturbative potentials ... More
Quantum coherence fluctuation relationsFeb 16 2018Apr 19 2018We investigate manipulations of pure quantum states under incoherent or strictly incoherent operations assisted by a coherence battery, that is, a storage device whose degree of coherence is allowed to fluctuate in the process. This leads to the derivation ... More
Chain transitive sets for smooth strongly monotone dynamical systemsApr 08 2012Let K denote a compact invariant set for a strongly monotone semiflow in an ordered Banach space E, satisfying standard smoothness and compactness assumptions. Suppose the semiflow restricted to K is chain transitive. The main result is that either K ... More