Results for "Edward W. Schwieterman"

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Earth: Atmospheric Evolution of a Habitable PlanetMar 15 2018Our present-day atmosphere is often used as an analog for potentially habitable exoplanets, but Earth's atmosphere has changed dramatically throughout its 4.5 billion year history. For example, molecular oxygen is abundant in the atmosphere today but ... More
A limited habitable zone for complex lifeFeb 13 2019The habitable zone (HZ) is defined as the range of distances from a host star within which liquid water, a key requirement for life, may exist at a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain ... More
The Increasing Rotation Period of Comet 10P/Tempel 2Sep 15 2010We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band lightcurves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the ... 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
A Quarter-Century of Observations of Comet 10P/Tempel 2 at Lowell Observatory: Continued Spin-Down, Coma Morphology, Production Rates, and Numerical ModelingOct 03 2012We report on photometry and imaging of Comet 10P/Tempel 2 obtained at Lowell Observatory from 1983 through 2011. We measured a nucleus rotation period of 8.950 +/- 0.002 hr from 2010 September to 2011 January. This rotation period is longer than the period ... 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
Rethinking CO Antibiosignatures in the Search for Life Beyond the Solar SystemMar 18 2019Some atmospheric gases have been proposed as counter indicators to the presence of life on an exoplanet if remotely detectable at sufficient abundance (i.e., antibiosignatures), informing the search for biosignatures and potentially fingerprinting uninhabited ... More
Atmospheric Seasonality as an Exoplanet BiosignatureJun 12 2018Current investigations of exoplanet biosignatures have focused on static evidence of life, such as the presence of biogenic gases like O2 or CH4. However, the expected diversity of terrestrial planet atmospheres and the likelihood of both false positives ... 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
Is the Pale Blue Dot unique? Optimized photometric bands for identifying Earth-like exoplanetsDec 01 2015Jan 29 2016The next generation of ground and space-based telescopes will image habitable planets around nearby stars. A growing literature describes how to characterize such planets with spectroscopy, but less consideration has been given to the usefulness of planet ... More
Detection of Ocean Glint and Ozone Absorption Using LCROSS Earth ObservationsMay 18 2014The Lunar CRater Observation and Sensing Satellite (LCROSS) observed the distant Earth on three occasions in 2009. These data span a range of phase angles, including a rare crescent phase view. For each epoch, the satellite acquired near-infrared and ... More
The Importance of UV Capabilities for Identifying Inhabited Exoplanets with Next Generation Space TelescopesJan 09 2018The strongest remotely detectable signature of life on our planet today is the photosynthetically produced oxygen (O2) in our atmosphere. However, recent studies of Earth's geochemical proxy record suggest that for all but the last ~500 million years, ... More
Identifying Planetary Biosignature Impostors: Spectral Features of CO and O4 Resulting from Abiotic O2/O3 ProductionFeb 17 2016O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the ... 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
Exoplanet Biosignatures: Future DirectionsMay 23 2017Aug 08 2017Exoplanet science promises a continued rapid accumulation of new observations in the near future, energizing a drive to understand and interpret the forthcoming wealth of data to identify signs of life beyond our Solar System. The large statistics of ... 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
False negatives for remote life detection on ocean-bearing planets: Lessons from the early EarthFeb 03 2017Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes through its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has ... More
Abiotic O$_{2}$ Levels on Planets around F, G, K, and M Stars: Possible False Positives for Life?Sep 25 2015In the search for life on Earth-like planets around other stars, the first (and likely only) information will come from the spectroscopic characterization of the planet's atmosphere. Of the countless number of chemical species terrestrial life produces, ... More
Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its EnvironmentMay 22 2017Here we review how environmental context can be used to interpret whether O2 is a biosignature in extrasolar planetary observations. This paper builds on the overview of current biosignature research discussed in Schwieterman et al. (2017), and provides ... More
Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric BiosignaturesDec 08 2016Nitrogen is a major nutrient for all life on Earth and could plausibly play a similar role in extraterrestrial biospheres. The major reservoir of nitrogen at Earth's surface is atmospheric N2, but recent studies have proposed that the size of this reservoir ... More
Exoplanet Biosignatures: A Review of Remotely Detectable Signs of LifeMay 16 2017Jun 25 2018In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous ... 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 Pale Orange Dot: The Spectrum and Habitability of Hazy Archean EarthOct 14 2016Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's ... More
The Astrobiology of the AnthropoceneDec 29 2017Jan 07 2018Human influence on the biosphere has been evident at least since the development of widespread agriculture, and some stratigraphers have suggested that the activities of modern civilization indicate a geological epoch transition. The study of the anthropocene ... More
The Importance of 3D General Circulation Models for Characterizing the Climate and Habitability of Terrestrial Extrasolar PlanetsMar 12 2019While recently discovered exotic new planet-types have both challenged our imaginations and broadened our knowledge of planetary system workings, perhaps the most compelling objective of exoplanet science is to detect and characterize habitable and possibly ... More
A simplified derivation of the Linear Noise ApproximationApr 24 2010Sep 28 2010Given a discrete stochastic process, for example a chemical reaction system or a birth and death process, we often want to find a continuous stochastic approximation so that the techniques of stochastic differential equations may be brought to bear. One ... More
A safety net for fast migrators: Interactions between gap-opening and sub-gap-opening bodies in a protoplanetary diskFeb 21 2005Young planets interact with their parent gas disks through tidal torques. An imbalance between inner and outer torques causes bodies of mass $\ga 0.1$ Earth masses to lose angular momentum and migrate inward rapidly relative to the disk; this is known ... More
Large scattering events and the formation of planetary systemsSep 16 2002In the nucleated instability picture of gas giant formation, the final stage is the rapid accretion of a massive gas envelope by a solid core, bringing about a tenfold or more increase in mass. This tends to trigger the scattering of any nearby bodies, ... More
Search for Baryons in the Radiative Penguin Decay b--> s gammaMay 05 2003We have searched for the baryon-containing radiative penguin decays B^- -> \Lambda p-bar \gamma and B^- -> \Sigma^0 p-bar \gamma, using a sample of 9.7 million BBbar events collected at the \Upsilon(4S) with the CLEO detector. We find no evidence for ... More
Nonphotosynthetic Pigments as Potential BiosignaturesMay 18 2015Previous work on possible surface reflectance biosignatures for Earth-like planets has typically focused on analogues to spectral features produced by photosynthetic organisms on Earth, such as the vegetation red edge. Although oxygenic photosynthesis, ... 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
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
Transitivity of an entangled choiceJan 18 2011We describe a quantum model of simple choice game (constructed upon entangled state of two qubits), which involves the fundamental problem of transitive - intransitive preferences. We compare attainability of optimal intransitive strategies in both classical ... More
When "I cut, you choose" method implies intransitivityOct 31 2013Sep 20 2014There is a common belief that humans and many animals follow transitive inference (choosing A over C on the basis of knowing that A is better than B and B is better than C). Transitivity seems to be the essence of rational choice. We present a theoretical ... More
Non-classical transport with angular-dependent path-length distributions. 1: TheorySep 18 2013Oct 08 2013This paper extends a recently introduced theory describing particle transport for random statistically homogeneous systems in which the distribution function p(s) for chord lengths between scattering centers is non-exponential. Here, we relax the previous ... More
Cosmological Bounds to the Magnetic Moment of Heavy Tau NeutrinosMar 12 1996The magnetic moment of tau neutrinos in the MeV mass range may be large enough to modify the cosmological freeze-out calculation and determine the tau-neutrino relic density. In this paper we revisit such a possibility. We calculate the evolution and ... More
Preheating and symmetry restoration in collisions of vacuum bubblesFeb 19 1996In first-order inflation a phase transition is completed by the collisions of expanding true-vacuum bubbles. If bubble collisions produce large numbers of soft scalar particles carrying quantum numbers associated with a spontaneously broken symmetry, ... More
A model of subjective supply-demand: the maximum Boltzmann/Shannon entropy solutionNov 13 2008We investigate activities that have different periods of duration. We define the profit intensity as a measure of this economic category. The profit intensity in a repeated trading has a unique property of attaining its maximum at a fixed point regardless ... More
The Astumian's ParadoxAug 27 2004We discuss some aspects of Astumian suggestions that combination of biased games (Parrondo's paradox) can explain performance of molecular motors. Unfortunately the model is flawed by explicit asymmetry overlooked by the author. In addition, we show that ... More
Kelly Criterion revisited: optimal betsJul 18 2006Kelly criterion, that maximizes the expectation value of the logarithm of wealth for bookmaker bets, gives an advantage over different class of strategies. We use projective symmetries for a explanation of this fact. Kelly's approach allows for an interesting ... More
The relativistic velocity addition law optimizes a forecast gambler's profitSep 26 2007We extend the projective covariant bookmaker's bets model to the forecasting gamblers case. The probability of correctness of forecasts shifts probabilities of branching. The formula for the shift of probabilities leads to the velocity addition rule of ... More
The InterHourly-Variability (IHV) Index of Geomagnetic Activity and its Use in Deriving the Long-term Variation of Solar Wind SpeedJun 07 2007We describe the derivation of the InterHourly Variability (IHV) index of geomagnetic activity. The IHV-index for a geomagnetic element is mechanically derived from hourly values as the sum of the unsigned differences between adjacent hours over a seven-hour ... More
Heliospheric Magnetic Field 1835-2009Feb 15 2010Mar 27 2010We use recently acquired geomagnetic archival data to extend our long-term reconstruction of the HMF strength. The 1835-2009 HMF series is based on an updated and substantiated IDV series from 1872-onwards and on Bartels' extension, by proxy, of his u-series ... More
Non-classical transport with angular-dependent path-length distributions. 2: Application to pebble bed reactor coresSep 24 2013Oct 08 2013We describe an analysis of neutron transport in the interior of model pebble bed reactor (PBR) cores, considering both crystal and random pebble arrangements. Monte Carlo codes were developed for (i) generating random realizations of the model PBR core, ... More
Dibaryons cannot be the dark matterSep 17 2018The hypothetical $SU(3)$ flavor-singlet dibaryon state $S$ with strangeness $-2$ has been discussed as a dark-matter candidate capable of explaining the curious 5-to-1 ratio of the mass density of dark matter to that of baryons. We study the early-universe ... More
Robust Designs via Geometric ProgrammingAug 22 2018An approximate formulation of a robust geometric program (RGP) as a convex program is proposed. Interest in using geometric programs (GPs) to model complex engineering systems has been growing, and this has motivated explicitly modeling the uncertainties ... More
On the reheating stage after inflationJul 18 2003We point out that inflaton decay products acquire plasma masses during the reheating phase following inflation. The plasma masses may render inflaton decay kinematicaly forbidden, causing the temperature to remain frozen for a period at a plateau value. ... More
Lorentz invariance violation in top-down scenarios of ultrahigh energy cosmic ray creationJun 29 2003Jan 28 2004The violation of Lorentz invariance (LI) has been invoked in a number of ways to explain issues dealing with ultrahigh energy cosmic ray (UHECR) production and propagation. These treatments, however, have mostly been limited to examples in the proton-neutron ... More
Relating Spectral Indices to Tensor and Scalar Amplitudes in InflationMar 01 1994Mar 19 1994Within an expansion in slow-roll inflation parameters, we derive the complete second-order expressions relating the ratio of tensor to scalar density perturbations and the spectral index of the scalar spectrum. We find that ``corrections'' to previously ... More
GUT Baryogenesis after PreheatingJun 07 1996Oct 24 1996At the end of inflation the universe is frozen in a near zero-entropy state with energy density in a coherent scalar field and must be ``defrosted'' to produce the observed entropy and baryon number. We propose that the baryon asymmetry is generated by ... More
Representing Structural Information of Helical Charge Distributions in Cylindrical CoordinatesDec 20 1996Structural information in the local electric field produced by helical charge distributions, such as dissolved DNA, is revealed in a straightforward manner employing cylindrical coordinates. Comparison of structure factors derived in terms of cylindrical ... More
Non-Gaussianity from Broken SymmetriesNov 07 2005Recently we studied inflation models in which the inflaton potential is characterized by an underlying approximate global symmetry. In the first work we pointed out that in such a model curvature perturbations are generated after the end of the slow-roll ... More
Parameter estimation by fixed point of function of information processing intensityMar 31 2014We present a new method of estimating the dispersion of a distribution which is based on the surprising property of a function that measures information processing intensity. It turns out that this function has a maximum at its fixed point. We use a fixed-point ... More
Phase groups and the origin of non-locality for qubitsMar 25 2010We describe a general framework in which we can precisely compare the structures of quantum-like theories which may initially be formulated in quite different mathematical terms. We then use this framework to compare two theories: quantum mechanics restricted ... More
Schrödinger type equation for subjective identification of supply and demandDec 20 2018The present authors have put forward a quantum game theory based model of market prices movements. By using Fisher information, we present a construction of an equation of Schr\"{o}dinger type for probability distributions for relationship between demand ... More
Vector Bundles over Elliptic FibrationsSep 26 1997This paper gives various methods for constructing vector bundles over elliptic curves and more generally over families of elliptic curves. We construct universal families over generalized elliptic curves via spectral cover methods and also by extensions, ... More
Fast approximation algorithms for $p$-centres in large $δ$-hyperbolic graphsApr 25 2016We provide a quasilinear time algorithm for the $p$-center problem with an additive error less than or equal to 3 times the input graph's hyperbolic constant. Specifically, for the graph $G=(V,E)$ with $n$ vertices, $m$ edges and hyperbolic constant $\delta$, ... More
Principal G-bundles over elliptic curvesJul 07 1997Feb 23 1998Let $G$ be a simple and simply connected complex Lie group. We discuss the moduli space of holomorphic semistable principal $G$ bundles over an elliptic curve $E$. In particular we give a new proof of a theorem of Looijenga and Bernshtein-Shvartsman, ... More
Cosmological background solutions and cosmological backreactionsJan 28 2009Nov 20 2009The cosmological backreaction proposal, which attempts to account for observations without a primary dark energy source in the stress-energy tensor, has been developed and discussed by means of different approaches. Here, we focus on the concept of cosmological ... More
Light-cone averages in a swiss-cheese universeOct 29 2007Dec 21 2007We analyze a toy swiss-cheese cosmological model to study the averaging problem. In our model, the cheese is the EdS model and the holes are constructed from a LTB solution. We study the propagation of photons in the swiss-cheese model, and find a phenomenological ... More
Light-cone observations and cosmological models: implications for inhomogeneous models mimicking dark energyNov 19 2009Cosmological observables are used to construct cosmological models. Since cosmological observations are limited to the light cone, a fixed number of observables (even measured to arbitrary accuracy) may not uniquely determine a cosmological model without ... More
Large-amplitude isothermal fluctuations and high-density dark-matter clumpsMar 07 1994Large-amplitude isothermal fluctuations in the dark matter energy density, parameterized by $\Phi\equiv\delta\rhodm/\rhodm$, are studied within the framework of a spherical collapse model. For $\Phi \ga 1$, a fluctuation collapses in the radiation-dominated ... More
Non-Linear Axion Dynamics and Formation of Cosmological Pseudo-SolitonsNov 15 1993The $(3+1)$-dimensional evolution of an inhomogeneous axion field configuration around the QCD epoch is studied numerically, including important non-linear effects due to the attractive self-interaction. It is found that axion perturbations on scales ... More
Planetary Migration and Eccentricity and Inclination Resonances in Extrasolar Planetary SystemsJul 28 2009The differential migration of two planets due to planet-disk interaction can result in capture into the 2:1 eccentricity-type mean-motion resonances. Both the sequence of 2:1 eccentricity resonances that the system is driven through by continued migration ... More
Exoplanet Diversity in the Era of Space-based Direct Imaging MissionsMar 10 2018This whitepaper discusses the diversity of exoplanets that could be detected by future observations, so that comparative exoplanetology can be performed in the upcoming era of large space-based flagship missions. The primary focus will be on characterizing ... More
An Introduction To The Web-Based FormalismJun 12 2015Jun 22 2016This paper summarizes our rather lengthy paper, "Algebra of the Infrared: String Field Theoretic Structures in Massive ${\cal N}=(2,2)$ Field Theory In Two Dimensions," and is meant to be an informal, yet detailed, introduction and summary of that larger ... More
Do transitive preferences always result in indifferent divisions?Dec 30 2014Feb 10 2015The transitivity of preferences is one of the basic assumptions used in the theory of games and decisions. It is often equated with rationality of choice and is considered useful in building rankings. Intransitive preferences are considered paradoxical ... More
A Cryptographic Escrow for Treaty Declarations and Step-by-Step VerificationSep 11 2018The verification of arms-control and disarmament agreements requires states to provide declarations, including information on sensitive military sites and assets. There are important cases, however, where negotiations of these agreements are impeded because ... More
Variations in Abundance Enhancements in Impulsive Solar Energetic-Particle Events and Related CMEs and FlaresJul 29 2014We study event-to-event variations in the abundance enhancements of the elements He through Pb for Fe-rich impulsive solar energetic-particle (SEP) events, and their relationship with properties of associated coronal mass ejections (CMEs) and solar flares. ... More
A Green Laser Pointer HazardAug 09 2010An inexpensive green laser pointer was found to emit 20 mW of infrared radiation during normal use. This is potentially a serious hazard that would not be noticed by most users of such pointers. We find that this infrared emission derives from the design ... More
Incomplete Nested DissectionMay 23 2018We present an asymptotically faster algorithm for solving linear systems in well-structured 3-dimensional truss stiffness matrices. These linear systems arise from linear elasticity problems, and can be viewed as extensions of graph Laplacians into higher ... More
First Determination of the Distance and Fundamental Properties of an Eclipsing Binary in The Andromeda GalaxyNov 01 2005We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3-mag semi-detached system with components of late-O and early-B spectral types. From the light and radial velocity ... More
Enhanced signal of astrophysical tau neutrinos propagating through EarthNov 26 2001Earth absorbs $\nue$ and $\numu$ of energies above about 100 TeV. As is well-known, although $\nutau$ will also disappear through charged-current interactions, the $\nutau$ flux will be regenerated by prompt tau decays. We show that this process also ... More
Gravitational production of super-Hubble-mass particles: an analytic approachDec 01 2018Dec 08 2018Through a mechanism similar to perturbative particle scattering, particles of mass $m_\chi$ larger than the Hubble expansion rate $H_\mathrm{inf}$ during inflation can be gravitationally produced at the end of inflation without the exponential suppression ... More
Superheavy dark matterFeb 05 1998May 26 1998We show that in large-field inflationary scenarios, superheavy (many orders of magnitude larger than the weak scale) dark matter will be produced in cosmologically interesting quantities if superheavy stable particles exist in the mass spectrum. We show ... More
Are ultrahigh energy cosmic rays signals of supersymmetry?Jul 02 1997Dec 19 1997We investigate the possibility that cosmic rays of energy larger than the Greisen-Zatsepin-Kuzmin cutoff are not nucleons, but a new stable, massive, hadron that appears in many extensions of the standard model. We focus primarily on the S^0, a uds-gluino ... More
Nonthermal Supermassive Dark MatterMay 27 1998Sep 25 1998We discuss several cosmological production mechanisms for nonthermal supermassive dark matter and argue that dark matter may be elementary particles of mass much greater than the weak scale. Searches for dark matter should not be limited to weakly interacting ... More
The subpulse modulation properties of pulsars at 21 cmJul 12 2005We present the results of a systematic, unbiased search for subpulse modulation of 187 pulsars performed with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands at an observing wavelength of 21 cm. Using new observations and archival WSRT ... More
Statistics of the drifting subpulse phenomenonMay 08 2006We present the statistical results of a systematic, unbiased search for subpulse modulation of 187 pulsars performed with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands at an observing wavelength of 21 cm (Weltevrede et al. 2006). ... More
Exotic massive hadrons and ultra-high energy cosmic raysMay 11 1998Oct 02 1998We investigate the proposal that primary cosmic rays of energy above the Greisen-Zatsepin-Kuzmin cutoff are exotic massive strongly interacting particles (uhecrons). We study the properties of air showers produced by uhecrons and find that masses in excess ... More
WMAPping inflationary physicsMay 12 2003Aug 01 2003We extract parameters relevant for distinguishing among single-field inflation models from the Wilkinson Microwave Anisotropy Probe (WMAP) data set, and from a combination of the WMAP data and seven other Cosmic Microwave Background (CMB) experiments. ... More
From mean-motion resonances to scattered planets: Producing the Solar System, eccentric exoplanets and Late Heavy BombardmentsJun 08 2007We show that interaction with a gas disk may produce young planetary systems with closely-spaced orbits, stabilized by mean-motion resonances between neighbors. On longer timescales, after the gas is gone, interaction with a remnant planetesimal disk ... More
Revealing Carrier-Envelope Phase through Frequency Mixing and Interference in Frequency Resolved Optical GatingJan 20 2015We demonstrate that full temporal characterisation of few-cycle electromagnetic pulses, including retrieval of the carrier envelope phase (CEP), can be directly obtained from Frequency Resolved Optical Gating (FROG) techniques in which the interference ... More
Error correcting codes for adiabatic quantum computationDec 20 2005Oct 10 2006Recently, there has been growing interest in using adiabatic quantum computation as an architecture for experimentally realizable quantum computers. One of the reasons for this is the idea that the energy gap should provide some inherent resistance to ... More
Modeling Thermal Fluctuations: Phase Mixing and PercolationDec 05 1995We consider the nonequilibrium dynamics of a a real scalar field in a degenerate double-well potential. The system is prepared in the lowest free energy state in one of the wells and the dynamics is driven by the coupling of the field to a thermal bath. ... More
The Growth & Migration of Jovian Planets in Evolving Protostellar Disks with Dead ZonesSep 22 2008The growth of Jovian mass planets during migration in their protoplanetary disks is one of the most important problems that needs to be solved in light of observations of the exosolar planets. Studies of the migration of planets in standard gas disk models ... More
Saving Planetary Systems: Dead Zones & Planetary MigrationJun 09 2006Jan 16 2007The tidal interaction between a disk and a planet leads to the planet's migration. A long-standing question regarding this mechanism is how to stop the migration before planets plunge into their central stars. In this paper, we propose a new, simple mechanism ... More
The Radionactive UniverseJun 17 2003Aug 04 2003In a large class of extra-dimensional models, a scalar degree of freedom known as the radion is long-lived, or even stable, on cosmological scales. In this paper we investigate the impact of radionactivity on the evolution of the universe. We demonstrate ... More
Ribbons on the CBR Sky: A Powerful Test of a Baryon Symmetric UniverseApr 09 1997May 02 1997If the Universe consists of domains of matter and antimatter, annihilations at domain interfaces leave a distinctive imprint on the Cosmic Background Radiation (CBR) sky. The signature is anisotropies in the form of long, thin ribbons of width $\theta_W\sim ... More
Structure of the Draco Dwarf Spheroidal GalaxyJan 17 2002This article studies the structure of the Draco dwarf spheroidal galaxy with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry ... More
Revisiting the Sunspot NumberJul 11 2014Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sunspot counts that retrace the last 4 centuries, since the invention of the ... More
The Neutron Star Mass-Radius Relation and the Equation of State of Dense MatterMay 31 2012The equation of state (EOS) of dense matter has been a long-sought goal of nuclear physics. Equations of state generate unique mass versus radius (M-R) relations for neutron stars, the ultra-dense remnants of stellar evolution. In this work, we determine ... More
Type I X-ray Bursts at Low Accretion RatesNov 02 2006Nov 02 2006Neutron stars, with their strong surface gravity, have interestingly short timescales for the sedimentation of heavy elements. Recent observations of unstable thermonuclear burning (observed as X-ray bursts) on the surfaces of slowly accreting neutron ... More
Resonance Trapping in Protoplanetary Disks. I. Coplanar SystemsJan 12 2008Sep 23 2008Mean-motion resonances (MMRs) are likely to play an important role both during and after the lifetime of a protostellar gas disk. We study the dynamical evolution and stability of planetary systems containing two giant planets on circular orbits near ... More
The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run?Aug 09 2007(abridged) We present kinematic results for a sample of 387 stars located near Leo I based on spectra obtained with the MMT's Hectochelle spectrograph near the MgI/Mgb lines. We estimate the mean velocity error of our sample to be 2.4 km/s, with a systematic ... More
High resolution cathodoluminescence hyperspectral imaging of surface features in InGaN/GaN multiple quantum well structuresFeb 09 2011Jul 18 2011InGaN/GaN multiple quantum wells (MQWs) have been studied by using cathodoluminescence hyperspectral imaging with high spatial resolution. Variations in peak emission energies and intensities across trench-like features and V-pits on the surface of the ... More
Induced density correlations in a sonic black hole condensateMay 04 2017Sep 27 2017Analog black/white hole pairs, consisting of a region of supersonic flow, have been achieved in a recent experiment by J. Steinhauer using an elongated Bose-Einstein condensate. A growing standing density wave, and a checkerboard feature in the density-density ... More
Momentum-space engineering of gaseous Bose-Einstein condensatesSep 03 2010Nov 19 2010We show how the momentum distribution of gaseous Bose--Einstein condensates can be shaped by applying a sequence of standing-wave laser pulses. We present a theory, whose validity for was demonstrated in an earlier experiment [L.\ Deng, et al., \prl {\bf ... More
Oligarchic growth of giant planetsMar 12 2003Runaway growth ends when the largest protoplanets dominate the dynamics of the planetesimal disk; the subsequent self-limiting accretion mode is referred to as ``oligarchic growth.'' Here, we begin by expanding on the existing analytic model of the oligarchic ... More
On the relic abundance of light photinosMar 22 1997We solve the coupled Boltzmann equation for the system of light photinos interacting with pions and $R^0$'s (the gluon-gluino bound state) to determine the relic abundance of light photinos in the light gaugino scenario. Cosmology bounds the ratio r of ... More