Results for "Tyler D. Robinson"

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Characterizing Exoplanet HabitabilityJan 18 2017Nov 21 2017A habitable exoplanet is a world that can maintain stable liquid water on its surface. Techniques and approaches to characterizing such worlds are essential, as performing a census of Earth-like planets that may or may not have life will inform our understanding ... More
Temperature Fluctuations as a Source of Brown Dwarf VariabilityMar 10 2014Apr 23 2014A number of brown dwarfs are now known to be variable with observed amplitudes as large as 10-30% at some wavelengths. While spatial inhomogeneities in cloud coverage and thickness are likely responsible for much of the observed variability, it is possible ... More
Maximizing the ExoEarth Candidate Yield from a Future Direct Imaging MissionSep 17 2014Oct 28 2014ExoEarth yield is a critical science metric for future exoplanet imaging missions. Here we estimate exoEarth candidate yield using single visit completeness for a variety of mission design and astrophysical parameters. We review the methods used in previous ... More
Abiotic Ozone and Oxygen in Atmospheres Similar to Prebiotic EarthJul 09 2014The search for life on planets outside our solar system will use spectroscopic identification of atmospheric biosignatures. The most robust remotely-detectable potential biosignature is considered to be the detection of oxygen (O_2) or ozone (O_3) simultaneous ... More
Stability of CO2 Atmospheres on Desiccated M Dwarf ExoplanetsJan 27 2015May 20 2015We investigate the chemical stability of CO2-dominated atmospheres of desiccated M dwarf terrestrial exoplanets using a 1-dimensional photochemical model. Around Sun-like stars, CO2 photolysis by Far-UV (FUV) radiation is balanced by recombination reactions ... More
Six Years of Sustained Activity from Active Asteroid (6478) GaultApr 23 2019May 02 2019We present archival observations demonstrating that main belt asteroid (6478) Gault has an extensive history of comet-like activity. Outbursts have taken place during multiple epochs since 2013 and at distances extending as far as 2.68 au, nearly aphelion. ... More
Detecting and Constraining N$_2$ Abundances in Planetary Atmospheres Using Collisional PairsJul 28 2015Characterizing the bulk atmosphere of a terrestrial planet is important for determining surface pressure and potential habitability. Molecular nitrogen (N$_2$) constitutes the largest fraction of Earth$'$s atmosphere and is likely to be a major constituent ... More
Spectrum-driven Planetary Deglaciation Due to Increases in Stellar LuminosityMar 14 2014Distant planets in globally ice-covered, "snowball", states may depend on increases in their host stars' luminosity to become hospitable for surface life. Using a General Circulation Model (GCM), we simulated the equilibrium climate response of a planet ... More
Earthshine as an Illumination Source at the MoonMar 30 2019Earthshine is the dominant source of natural illumination on the surface of the Moon during lunar night, and at locations within permanently shadowed regions that never receive direct sunlight. As such, earthshine may enable the exploration of areas of ... More
Detecting Ocean Glint on Exoplanets Using Multiphase MappingJan 15 2019Rotational mapping and glint are two proposed methods to directly detect liquid water on the surface of habitable exoplanets. However, false positives for both methods may prevent the unambiguous detection of exoplanet oceans. We use simulations of Earth ... More
Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary SystemSep 20 2018The TRAPPIST-1 planetary system provides an unprecedented opportunity to study terrestrial exoplanet evolution with the James Webb Space Telescope (JWST) and ground-based observatories. Since M dwarf planets likely experience extreme volatile loss, the ... More
The Effect of Host Star Spectral Energy Distribution and Ice-Albedo Feedback on the Climate of Extrasolar PlanetsMay 29 2013Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. Here we explore this effect using a one dimensional (1-D), line-by-line, radiative-transfer ... More
Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike ExoplanetsFeb 09 2017Hazes are common in known planet atmospheres, and geochemical evidence suggests early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic haze formation ... More
The Center of Light: Spectroastrometric Detection of ExomoonsSep 04 2015Direct imaging of extrasolar planets with future space-based coronagraphic telescopes may provide a means of detecting companion moons at wavelengths where the moon outshines the planet. We propose a detection strategy based on the positional variation ... More
Characterizing Earth Analogs in Reflected Light: Atmospheric Retrieval Studies for Future Space TelescopesMar 16 2018Space-based high contrast imaging mission concepts for studying rocky exoplanets in reflected light are currently under community study. We develop an inverse modeling framework to estimate the science return of such missions given different instrument ... More
Generalized Chern-Simons action principles for gravityJun 30 2015Generalized differential forms are employed to construct generalized connections. Lorentzian four-metrics determined by certain of these connections satisfy Einstein's vacuum field equations when the connections are flat. Generalized Chern-Simons action ... More
A Theory of Exoplanet Transits with Light ScatteringJan 19 2017Oct 24 2018Exoplanet transit spectroscopy enables the characterization of distant worlds, and will yield key results for NASA's James Webb Space Telescope. However, transit spectra models are often simplified, omitting potentially important processes like refraction ... More
Completely Colorblind: Advances in Gray Techniques and Applications to Planets Near and FarNov 10 2015Gray models, which replace spectrally-resolved opacities with a wavelength independent mean opacity, are currently seeing wide and diverse application. In this brief review, we discuss both the history of gray techniques as well as recent applications ... More
Modeling the Infrared Spectrum of the Earth-Moon System: Implications for the Detection and Characterization of Earthlike Extrasolar Planets and their Moonlike CompanionsOct 17 2011Large surface temperatures on the illuminated hemisphere of the Moon can lead it to contribute a significant amount of flux to spatially unresolved infrared (IR) observations of the Earth-Moon system, especially at wavelengths where Earth's atmosphere ... More
Habitable zone predictions and how to test themMar 09 2019Mar 12 2019The habitable zone (HZ) is the region around a star(s) where standing bodies of water could exist on the surface of a rocky planet. The classical HZ definition makes a number of assumptions common to the Earth, including assuming that the most important ... More
The remote detectability of Earth's biosphere through time and the importance of UV capability for characterizing habitable exoplanetsMar 13 2019Thousands of planets beyond our solar system have been discovered to date, dozens of which are rocky in composition and are orbiting within the circumstellar habitable zone of their host star. The next frontier in life detection beyond our solar system ... More
Finding the Needles in the Haystacks: High-Fidelity Models of the Modern and Archean Solar System for Simulating Exoplanet ObservationsOct 17 2017We present two state-of-the-art models of the solar system, one corresponding to the present day and one to the Archean Eon 3.5 billion years ago. Each model contains spatial and spectral information for the star, the planets, and the interplanetary dust, ... More
The Habitability of Proxima Centauri b: II: Environmental States and Observational DiscriminantsAug 30 2016Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have ... More
Rotational Variability of Earth's Polar Regions: Implications for Detecting Snowball PlanetsFeb 21 2011We have obtained the first time-resolved, disc-integrated observations of Earth's poles with the Deep Impact spacecraft as part of the EPOXI Mission of Opportunity. These data mimic what we will see when we point next-generation space telescopes at nearby ... More
Observing the Atmospheres of Known Temperate Earth-sized Planets with JWSTAug 14 2017Nov 29 2017Nine transiting Earth-sized planets have recently been discovered around nearby late M dwarfs, including the TRAPPIST-1 planets and two planets discovered by the MEarth survey, GJ 1132b and LHS 1140b. These planets are the smallest known planets that ... More
exocartographer: A Bayesian Framework for Mapping Exoplanets in Reflected LightFeb 19 2018Future space telescopes will directly image extrasolar planets at visible wavelengths. Time-resolved reflected light from an exoplanet encodes information about atmospheric and surface inhomogeneities. Previous research has shown that the light curve ... More
Quasi-diagonal flowsDec 25 2008We introduce two notions for flows on quasi-diagonal C*-algebras, quasi-diagonal and pseudo-diagonal flows; the former being apparently stronger than the latter. We derive basic facts about these flows and give various examples. In addition we extend ... More
Linearized Flux Evolution (LiFE): A Technique for Rapidly Adapting Fluxes from Full-Physics Radiative Transfer ModelsMar 06 2018Solar and thermal radiation are critical aspects of planetary climate, with gradients in radiative energy fluxes driving heating and cooling. Climate models require that radiative transfer tools be versatile, computationally efficient, and accurate. Here, ... More
Constant-Force-Magnitude Chaotic OscillatorMar 24 2003A numerical model is presented for a mechanical oscillator in which the magnitude of the restoring force is constant. Unlike the harmonic oscillator, where force is proportional to displacement, this nonlinear system can be chaotic when externally driven. ... More
Lowest Terms RevisitedSep 13 2006In the September 1994 issue of Math Horizons the following problem is given in the Problem Section (p. 33, Problem 5): Lowest Terms - what fraction has the smallest denominator in the interval (19/94, 17/76)? In this paper we develop a general algorithm ... More
Common 0.1 bar Tropopause in Thick Atmospheres Set by Pressure-Dependent Infrared TransparencyDec 24 2013A minimum atmospheric temperature, or tropopause, occurs at a pressure of around 0.1 bar in the atmospheres of Earth, Titan, Jupiter, Saturn, Uranus and Neptune, despite great differences in atmospheric composition, gravity, internal heat and sunlight. ... More
An Analytic Radiative-Convective Model for Planetary AtmospheresSep 09 2012We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to ... More
Earth as an ExoplanetApr 11 2018The search for habitable and inhabited environments beyond our planet commonly focuses on analogs to Earth, especially in the case of exoplanets. Observations from ground-based facilities, satellites, and spacecraft have yielded a rich collection of data ... More
On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant PlanetsOct 23 2014The atmosphere of a brown dwarf or extrasolar giant planet controls the spectrum of radiation emitted by the object and regulates its cooling over time. While the study of these atmospheres has been informed by decades of experience modeling stellar and ... More
A Simple Model for Radiative and Convective Fluxes in Planetary AtmospheresAug 01 2018One-dimensional (vertical) models of planetary atmospheres typically balance the net solar and internal energy fluxes against the net thermal radiative and convective heat fluxes to determine an equilibrium thermal structure. Thus,simple models of shortwave ... More
Bayesian Vote Manipulation: Optimal Strategies and Impact on WelfareOct 16 2012Most analyses of manipulation of voting schemes have adopted two assumptions that greatly diminish their practical import. First, it is usually assumed that the manipulators have full knowledge of the votes of the nonmanipulating agents. Second, analysis ... More
Memory Efficient Experience Replay for Streaming LearningSep 16 2018Feb 23 2019In supervised machine learning, an agent is typically trained once and then deployed. While this works well for static settings, robots often operate in changing environments and must quickly learn new things from data streams. In this paradigm, known ... More
Implementing the three-particle quantization condition including higher partial wavesJan 21 2019Mar 04 2019We present an implementation of the relativistic three-particle quantization condition including both $s$- and $d$-wave two-particle channels. For this, we develop a systematic expansion about threshold of the three-particle divergence-free K matrix, ... More
Continuous-variable quantum teleportation of entanglementApr 03 2002Oct 31 2002Entangled coherent states can be used to determine the entanglement fidelity for a device that is designed to teleport coherent states. This entanglement fidelity is universal, in that the calculation is independent of the use of entangled coherent states ... More
Technical Report: Optimal Control of Piecwise-smooth Control Systems via Singular PerturbationsMar 28 2019Mar 31 2019This paper investigates optimal control problems formulated over a class of piecewise-smooth vector fields. Instead of optimizing over the discontinuous system directly, we instead formulate optimal control problems over a family of regularizations which ... More
An Empirical Evaluation of Allgatherv on Multi-GPU SystemsDec 14 2018Applications for deep learning and big data analytics have compute and memory requirements that exceed the limits of a single GPU. However, effectively scaling out an application to multiple GPUs is challenging due to the complexities of communication ... More
Parallel Sparse Tensor Decomposition in ChapelDec 14 2018In big-data analytics, using tensor decomposition to extract patterns from large, sparse multivariate data is a popular technique. Many challenges exist for designing parallel, high performance tensor decomposition algorithms due to irregular data accesses ... More
Implications for planetary system formation from interstellar object 1I/2017 U1 (`Oumuamua)Nov 03 2017Nov 09 2017The recently discovered minor body 1I/2017 U1 (`Oumuamua) is the first known object in our Solar System that is not bound by the Sun's gravity. Its hyperbolic orbit (eccentricity greater than unity) strongly suggests that it originated outside our Solar ... More
The Need for Laboratory Work to Aid in The Understanding of Exoplanetary AtmospheresFeb 19 2016Feb 23 2016Advancements in our understanding of exoplanetary atmospheres, from massive gas giants down to rocky worlds, depend on the constructive challenges between observations and models. We are now on a clear trajectory for improvements in exoplanet observations ... More
Spectroastrometry of rotating gas disks for the detection of supermassive black holes in galactic nuclei. I. Method and simulationsJan 07 2010This is the first in a series of papers in which we study the application of spectroastrometry in the context of gas kinematical studies aimed at measuring the mass of supermassive black holes. The spectroastrometrical method consists in measuring the ... More
DTM: Deformable Template MatchingApr 12 2016A novel template matching algorithm that can incorporate the concept of deformable parts, is presented in this paper. Unlike the deformable part model (DPM) employed in object recognition, the proposed template-matching approach called Deformable Template ... More
The Contribution from Scattered Light to Quasar Galaxy HostsMay 25 2009We present models representing the scattering of quasar radiation off free electrons and dust grains in geometries that approximate the structure of quasar host galaxies. We show that, for reasonable assumptions, scattering alone can easily produce ratios ... More
Study of Electron Transport in Organic and Inorganic Atomic Monolayer Based MOS/MOSFETSep 23 2014The wide research interest for the potential nanoelectronics applications are attracted by the organic and inorganic monolayer materials. In this work, we have studied the organic monolayer such as trichloro (1H,1H,2H,2H-perfluorooctyl)-silane (FOTS), ... More
Study Of Organic Monolayer Modified Metal Oxide Semiconductor Devices For High Temperature ApplicationsSep 23 2014We report fabrication and characteristics of an organic monolayer based Metal Oxide Semiconductor (MOS) device. In place of SiO2 oxide layer in the MOS configuration, we used 1H, 1H, 2H, 2H- perfluorooctyl trichlorosilane (FOTS) self-assembled monolayer ... More
Energy conservation in the 3D Euler equations on $\mathbb{T}^2\times \mathbb{R}_+$Nov 01 2016Jun 30 2017The aim of this paper is to prove energy conservation for the incompressible Euler equations in a domain with boundary. We work in the domain $\mathbb{T}^2\times\mathbb{R}_+$, where the boundary is both flat and has finite measure. However, first we study ... More
Energy conservation for the Euler equations on $\mathbb{T}^2\times \mathbb{R}_+$ for weak solutions defined without reference to the pressureJun 01 2018We study weak solutions of the incompressible Euler equations on $\mathbb{T}^2\times \mathbb{R}_+$; we use test functions that are divergence free and have zero normal component, thereby obtaining a definition that does not involve the pressure. We prove ... More
Operator-Valued Frames for the Heisenberg GroupSep 27 2014A classical result of Duffin and Schaeffer gives conditions under which a discrete collection of characters on $\mathbb{R}$, restricted to $E = (-1/2, 1/2)$, forms a Hilbert-space frame for $L^2(E)$. For the case of characters with period one, this is ... More
Search for a stochastic gravitational-wave signal in the second round of the Mock LISA Data ChallengesApr 25 2008The analysis method currently proposed to search for isotropic stochastic radiation of primordial or astrophysical origin with the Laser Interferometer Space Antenna (LISA) relies on the combined use of two LISA channels, one of which is insensitive to ... More
Support Vector Machine Application for Multiphase Flow Pattern PredictionJun 12 2018In this paper a data analytical approach featuring support vector machines (SVM) is employed to train a predictive model over an experimentaldataset, which consists of the most relevant studies for two-phase flow pattern prediction. The database for this ... More
Analytic Scattering and Refraction Models for Exoplanet Transit SpectraNov 03 2017Observations of exoplanet transit spectra are essential to understanding the physics and chemistry of distant worlds. The effects of opacity sources and many physical processes combine to set the shape of a transit spectrum. Two such key processes - refraction ... More
Detecting Oceans on Extrasolar Planets Using the Glint EffectAug 23 2010Glint, the specular reflection of sunlight off Earth's oceans, may reveal the presence of oceans on an extrasolar planet. As an Earth-like planet nears crescent phases, the size of the ocean glint spot increases relative to the fraction of illuminated ... More
Characterizing Rocky and Gaseous Exoplanets with 2-meter Class Space-based CoronagraphsJul 02 2015Nov 12 2015Several concepts now exist for small, space-based missions to directly characterize exoplanets in reflected light. Here, we develop an instrument noise model suitable for studying the spectral characterization potential of a coronagraph-equipped, space-based ... More
Feshbach molecule formation in a Bose-Fermi mixtureDec 04 2012Sep 10 2013We investigate magnetoassociation of ultracold fermionic Feshbach molecules in a mixture of $^{40}$K and $^{87}$Rb atoms, where we can create as many as $7\times 10^4$ $^{40}$K$^{87}$Rb molecules with a conversion efficiency as high as 45%. In the perturbative ... More
Multi-Switch: a Tool for Finding Potential Edge-Disjoint $1$-factorsAug 01 2015Let $n$ be even, let $\pi = (d_1, \ldots, d_n)$ be a graphic degree sequence, and let $\pi - k = (d_1 - k, \ldots, d_n - k)$ also be graphic. Kundu proved that $\pi$ has a realization $G$ containing a $k$-factor, or $k$-regular graph. Another way to state ... More
A Statistical Comparative Planetology Approach to Maximize the Scientific Return of Future Exoplanet Characterization EffortsMar 12 2019Provided that sufficient resources are deployed, we can look forward to an extraordinary future in which we will characterize potentially habitable planets. Until now, we have had to base interpretations of observations on habitability hypotheses that ... More
A note on H_infinity structuresNov 04 2013We give a source of examples of H_infinity ring structures that do not lift to E_infinity ring structures, based on Mandell's equivalence between certain cochain algebras and spaces.
Improved Hölder Continuity of Quasiconformal MapsMar 28 2018Quasiconformal maps in the complex plane are homeomorphisms that satisfy certain geometric distortion inequalities; infinitesimally, they map circles to ellipses with bounded eccentricity. The local distortion properties of these maps give rise to a certain ... More
Geometric Bounds for Favard LengthNov 27 2017Given a set in the plane, the average length of its projections over all directions is called Favard length. This quantity measures the size of a set, and is closely related to metric and geometric properties of the set such as rectifiability, Hausdorff ... More
The product formula in unitary deformation K-theoryMar 22 2005May 15 2006We prove that "unitary deformation K-theory" takes products of finitely generated groups to coproducts of algebra spectra over ku, the connective K-theory spectrum. Additionally, we give spectral sequences for computing the homotopy groups of the unitary ... More
Stretching and Rotation Sets of Quasiconformal MappingsOct 12 2017Quasiconformal maps in the plane are orientation preserving homeomorphisms that satisfy certain distortion inequalities; infinitesimally, they map circles to ellipses of bounded eccentricity. Such maps have many useful geometric distortion properties, ... More
Seymour's Second Neighborhood Conjecture for Subsets of VerticesAug 20 2018Jan 08 2019Seymour conjectured that every oriented simple graph contains a vertex whose second neighborhood is at least as large as its first. In this note, we put forward a conjecture that we prove is actually equivalent: every oriented simple graph contains a ... More
Structured ring spectra and displaysDec 27 2009We combine Lurie's generalization of the Hopkins-Miller theorem with work of Zink-Lau on displays to give a functorial construction of even-periodic commutative ring spectra, concentrated in chromatic layers 2 and above, associated to certain n by n invertible ... More
The Shimura curve of discriminant 15 and topological automorphic formsJan 15 2013Jan 16 2015We find defining equations for the Shimura curve of discriminant 15 over Z[1/15]. We then determine the graded ring of automorphic forms over the 2-adic integers, as well as the higher cohomology. We apply this to calculate the homotopy groups of a spectrum ... More
Loop-weighted WalkOct 12 2014May 30 2016Loop-weighted walk with parameter $\lambda\geq 0$ is a non-Markovian model of random walks that is related to the loop $O(N)$ model of statistical mechanics. A walk receives weight $\lambda^{k}$ if it contains $k$ loops; whether this is a reward or punishment ... More
Non-abelian convexity of based loop groupsSep 17 2015If $K$ is a compact, connected, simply connected Lie group, its based loop group $\Omega K$ is endowed with a Hamiltonian $S^1 \times T$ action, where $T$ is a maximal torus of $K$. Atiyah and Pressley examined the image of $\Omega K$ under the moment ... More
Galactic Outflows, Star Formation Histories, and Timescales in Starburst Dwarf Galaxies from STARBIRDSMay 12 2017Mar 29 2018Winds are predicted to be ubiquitous in low-mass, actively star-forming galaxies. Observationally, winds have been detected in relatively few local dwarf galaxies, with even fewer constraints placed on their timescales. Here, we compare galactic outflows ... More
Design, theory, and measurement of a polarization insensitive absorber for terahertz imagingJul 22 2008Aug 20 2008We present the theory, design, and realization of a polarization-insensitive metamaterial absorber for terahertz frequencies. We derive geometrical-independent conditions for effective medium absorbers in general, and for resonant metamaterials specically. ... More
Controlling Organization and Forces in Active Matter Through Optically-Defined BoundariesDec 22 2018Jan 11 2019Living systems are capable of locomotion, reconfiguration, and replication. To perform these tasks, cells spatiotemporally coordinate the interactions of force-generating, "active" molecules that create and manipulate non-equilibrium structures and force ... More
Classification of Singular Fibres on Rational Elliptic Surfaces in Characteristic ThreeOct 15 2004Mar 12 2005We determine and list all possible configurations of singular fibres on rational elliptic surfaces in characteristic three. In total, we find that 267 distinct configurations exist. This result complements Miranda and Persson's classification in characteristic ... More
Wave Physics as an Analog Recurrent Neural NetworkApr 29 2019Analog machine learning hardware platforms promise to be faster and more energy-efficient than their digital counterparts. Wave physics, as found in acoustics and optics, is a natural candidate for building analog processors for time-varying signals. ... More
Progress report on the relativistic three-particle quantization conditionOct 15 2018We describe recent work on the relativistic three-particle quantization condition, generalizing and applying the original formalism of Hansen and Sharpe, and of Brice\~no, Hansen and Sharpe. In particular, we sketch three recent developments: the generalization ... More
Multidimensional chemical modelling, II. Irradiated outflow wallsJun 03 2009Observations of the high-mass star forming region AFGL 2591 reveal a large abundance of CO+, a molecule known to be enhanced by far UV (FUV) and X-ray irradiation. In chemical models assuming a spherically symmetric envelope, the volume of gas irradiated ... More
Measuring chromatic aberrations in imaging systems using plasmonic nano-particlesAug 04 2015Chromatic aberration in optical systems arises from the wavelength dependence of a glass's refractive index. Polychromatic rays incident upon an optical surface are refracted at slightly different angles and in traversing an optical system follow distinct ... More
Broadband Focal Plane Wavefront Control of Amplitude and Phase AberrationsAug 15 2012The Stroke Minimization algorithm developed at the Princeton High Contrast Imaging Laboratory has proven symmetric dark hole generation using minimal stroke on two deformable mirrors (DM) in series. The windowed approach to Stroke Minimization has proven ... More
Sub-millimeter emission from type Ia supernova host galaxies at z=0.5Dec 03 2003We present deep sub-millimetre observations of seventeen galaxies at z=0.5, selected through being hosts of a type 1a supernova. Two galaxies are detected directly, and the sample is detected statistically with a mean 850 micron flux of 1.01mJy +/- 0.33mJy, ... More
Starburst and AGN activity in ultraluminous infrared galaxiesApr 08 2003(Abridged) We examine the power source of 41 local Ultraluminous Infrared Galaxies using archival infrared and optical photometry. We fit the observed Spectral Energy Distributions (SEDs) with starburst and AGN components; each component being drawn from ... More
Life Beyond the Solar System: Remotely Detectable BiosignaturesJan 20 2018For the first time in human history, we will soon be able to apply the scientific method to the question "Are We Alone?" The rapid advance of exoplanet discovery, planetary systems science, and telescope technology will soon allow scientists to search ... More
Cold Dust in (Some) High z Supernova Host GalaxiesJul 27 2005We present deep submillimetre photometry for 14 galaxies at z=0.5 that are hosts of type 1a supernovae, with the aim of examining the evolution of dust mass and extinction in normal galaxies. We combine these results with our previous observations of ... More
Roadmap For Small Bodies Exploration: Theoretical StudiesMar 25 2011Mar 28 2011This document covers five broad topics from theory of small bodies: planetesimal formation, cosmochemistry, thermal evolution, collisions and dynamics. Each of these topics is described in a separate section, where we prioritize selected main issues over ... More
Mid-Infrared Spectroscopy of Optically Faint Extragalactic 70 micron SourcesMar 06 2009We present mid-infrared spectra of sixteen optically faint sources with 70 micron fluxes in the range 19-38mJy. The sample spans a redshift range of 0.35<z<1.9, with most lying between 0.8<z<1.6, and has infrared luminosities of 10^{12} - 10^{13} solar ... More
Lyman Break Galaxies at z~1 and the evolution of the dust attenuation in star-forming galaxies with the redshiftJun 06 2007Aug 21 2007Ultraviolet (UV) galaxies have been selected from GALEX. The presence of a FUV-dropout in their spectral energy distributions proved to be a very complete (83.3%) but not very efficient (21.4%) tool for identifying Lyman Break Galaxies (LBGs) at z~1. ... More
E-infinity obstruction theoryJan 08 2013The space of E-infinity structures on an simplicial operad C is the limit of a tower of fibrations, so its homotopy is the abutment of a Bousfield-Kan fringed spectral sequence. The spectral sequence begins (under mild restrictions) with the stable cohomotopy ... More
Partition complexes, duality and integral tree representationsOct 26 2004We show that the poset of non-trivial partitions of 1,2,...,n has a fundamental homology class with coefficients in a Lie superalgebra. Homological duality then rapidly yields a range of known results concerning the integral representations of the symmetric ... More
A classical vertex algebra constructed with the use of some logarithmic formal calculusJun 08 2011Jun 21 2011Using some new logarithmic formal calculus, we construct a well known vertex algebra, obtaining the Jacobi identity directly, in an essentially self-contained treatment.
Asynchronous logic circuits and sheaf obstructionsAug 16 2010This article exhibits a particular encoding of logic circuits into a sheaf formalism. The central result of this article is that there exists strictly more information available to a circuit designer in this setting than exists in static truth tables, ... More
Eternal solutions and heteroclinic orbits of a semilinear parabolic equationApr 30 2008This dissertation describes the space of heteroclinic orbits for a class of semilinear parabolic equations, focusing primarily on the case where the nonlinearity is a second degree polynomial with variable coefficients. Along the way, a new and elementary ... More
Classification of connecting solutions of semilinear parabolic equationsSep 17 2007For a given semilinear parabolic equation with polynomial nonlinearity, many solutions blow up in finite time. For a certain large class of these equations, we show that some of the solutions which do not blow up actually tend to equilibria. The characterizing ... More
The Need for Laboratory Measurements and Ab Initio Studies to Aid Understanding of Exoplanetary AtmospheresMay 16 2019We are now on a clear trajectory for improvements in exoplanet observations that will revolutionize our ability to characterize their atmospheric structure, composition, and circulation, from gas giants to rocky planets. However, exoplanet atmospheric ... More
Lyman Break Galaxies and Luminous IR Galaxies at z ~ 1Jan 11 2007We use deep GALEX images of CDFS in UV to define the first large sample of 420 Lyman Break Galaxies at z~1. We use a PSF fitting to estimate UV magnitudes on these deep crowded images. Deep Spitzer IRAC and MIPS provide the first detection of a large ... More
Sheaf and duality methods for analyzing multi-model systemsApr 15 2016Nov 03 2016There is an interplay between models, specified by variables and equations, and their connections to one another. This dichotomy should be reflected in the abstract as well. Without referring to the models directly -- only that a model consists of spaces ... More
Instability of an equilibrium of a partial differential equationApr 30 2007Sep 09 2007A nonlinear parabolic differential equation with a quadratic nonlinearity is presented which has at least one equilibrium. The linearization about this equilibrium is asymptotically stable, but by using a technique inspired by H. Fujita, we show that ... More
Instability of an equilibrium with negative definite linearizationFeb 19 2007Feb 20 2007A nonlinear parabolic differential equation is presented which has at least one equilibrium. This equilibrium is shown to have a negative definite linearization, but a spectrum which includes zero. An elementary construction shows that the equilibrium ... More
Analyzing wireless communication network vulnerability with homological invariantsNov 06 2013This article explains how sheaves and homology theory can be applied to simplicial complex models of wireless communication networks to study their vulnerability to jamming. It develops two classes of invariants (one local and one global) for studying ... More
Sheaves are the canonical datastructure for sensor integrationMar 04 2016Dec 02 2016A sensor integration framework should be sufficiently general to accurately represent all information sources, and also be able to summarize information in a faithful way that emphasizes important, actionable information. Few approaches adequately address ... More
The Nyquist theorem for cellular sheavesJul 27 2013We develop a unified sampling theory based on sheaves and show that the Shannon-Nyquist theorem is a cohomological consequence of an exact sequence of sheaves. Our theory indicates that there are additional cohomological obstructions for higher-dimensional ... More