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Results for "Janice Lee"

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Dwarf Galaxy Starburst Statistics in the Local VolumeOct 28 2008An unresolved question in galaxy evolution is whether the star formation histories of low mass systems are preferentially dominated by starbursts or modes that are more quiescent and continuous. Here, we quantify the prevalence of global starbursts in ... More
Star Formation Rate Distributions: Inadequacy of the Schechter FunctionSep 04 2012In this paper we posit that galaxy luminosity functions (LFs) come in two fundamentally different types depending on whether the luminosity traces galaxy stellar mass or its current star formation rate (SFR). Mass function types reflect the older stars ... More
Dust-Corrected Star Formation Rates of Galaxies. I. Combinations of H-alpha and Infrared TracersAug 03 2009We combine H-alpha emission-line and infrared continuum measurements of two samples of nearby galaxies to derive dust attenuation-corrected star formation rates (SFRs). We use a simple energy balance based method that has been applied previously to HII ... More
Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift AnalogsApr 16 2018We study dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using GALEX, SDSS, and WISE photometry calibrated on Herschel-ATLAS. We use a new method of constraining SED ... More
Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins SpectrographMar 22 2016We report on the detection of Lyman continuum radiation in two nearby starburst galaxies. Tol 0440-381, Tol 1247-232 and Mrk 54 were observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescopes. The three galaxies have radial velocities ... More
On the Mass-Metallicity-Star Formation Rate Relation for Galaxies at $z\sim 2$Jun 09 2015Recent studies have shown that the local mass-metallicity (M-Z) relation depends on the specific star formation rate (SSFR). Whether such a dependence exists at higher redshifts, and whether the resulting M-Z-SFR relation is redshift invariant, is debated. ... More
A Deeper Look at Faint H$α$ Emission in Nearby Dwarf GalaxiesJan 02 2016We present deep H$\alpha$ imaging of three nearby dwarf galaxies, carefully selected to optimize observations with the Maryland-Magellan Tunable Filter (MMTF) on the Magellan 6.5m telescope. An effective bandpass of $\sim$13\AA\ is used, and the images ... More
Metal Abundances of KISS Galaxies III. Nebular Abundances for Fourteen Galaxies and the Luminosity-Metallicity Relationship for HII GalaxiesAug 18 2004We report results from the third in a series of nebular abundance studies of emission-line galaxies from the KPNO International Spectroscopic Survey (KISS). Galaxies with coarse metallicity estimates of 12 + log(O/H) less than 8.2 dex were selected for ... More
Emission-Line Galaxy Surveys as Probes of the Spatial Distribution of Dwarf Galaxies. I. The University of Michigan SurveyJan 21 2000Objective-prism surveys which select galaxies on the basis of line-emission are extremely effective at detecting low-luminosity galaxies and constitute some of the deepest available samples of dwarfs. In this study, we confirm that emission-line galaxies ... More
Transmission of phase information between electrons and holes in grapheneApr 16 2013We have studied quantum interference between electrons and holes in a split-ring gold interferometer with graphene arms, one of which contained a pn junction. The carrier type, the pn junction and the phase of the oscillations in a magnetic field were ... More
Gas Motion Study of Lya Emitters at z~2 Using UV and Optical Spectral LinesJun 11 2012Jan 11 2013We present the results of Magellan/MMIRS and Keck/NIRSPEC spectroscopy for five Lya emitters (LAEs) at z=2.2 for which high-resolution FUV spectra from Magellan/MagE are available. We detect nebular emission lines including Ha on the individual basis ... More
The Connection Between Galaxy Environment and the Luminosity Function Slopes of Star-Forming RegionsJul 13 2016Jul 29 2016We present the first study of GALEX far ultra-violet (FUV) luminosity functions of individual star-forming regions within a sample of 258 nearby galaxies spanning a large range in total stellar mass and star formation properties. We identify ~65,000 star-forming ... More
The Nature of the Second Parameter in the IRX-beta Relation for Local GalaxiesJul 05 2013We present an analysis of 98 galaxies of low-dust content, selected from the Spitzer Local Volume Legacy survey, aimed at examining the relation between the ultraviolet (UV) color, beta, and dust attenuation in normal star-forming galaxies. The IRX-beta ... More
UV/H-alpha TurmoilNov 09 2010A great deal of our understanding of star formation in the local universe has been built upon an extensive foundation of H-alpha observational studies. However, recent work in the ultraviolet (UV) with GALEX has shown that star formation rates (SFRs) ... More
Metal Abundances of KISS Galaxies. IV. Galaxian Luminosity-Metallicity Relations in the Optical and Near-IRFeb 09 2005We explore the galaxian luminosity-metallicity (L-Z) relationship in both the optical and the near-IR using a combination of optical photometric and spectroscopic observations from the KPNO International Spectroscopic Survey (KISS) and near-infrared photometry ... More
Resonant Readout of a Persistent Current QubitJan 12 2005We have implemented a resonant circuit that uses a SQUID as a flux-sensitive Josephson inductor for qubit readout. In contrast to the conventional switching current measurement that generates undesired quasi-particles when the SQUID switches to the voltage ... More
Nonlinear resonant behavior of the dispersive readout scheme for a superconducting flux qubitSep 22 2006A nonlinear resonant circuit comprising a SQUID magnetometer and a parallel capacitor is studied as a readout scheme for a persistent-current (PC) qubit. The flux state of the qubit is detected as a change in the Josephson inductance of the SQUID magnetometer, ... More
The Star Formation Demographics of Galaxies in the Local VolumeNov 09 2007We examine the connections between the current global star formation activity, luminosity, dynamical mass and morphology of galaxies in the Local Volume, using H-alpha data from the 11 Mpc H-alpha and Ultraviolet Galaxy Survey (11HUGS). Taking the equivalent ... More
Life in the last lane: Star formation and chemical evolution in an extremely gas-rich dwarfNov 10 2007We present an analysis of HI, H-alpha, and oxygen abundance data for NGC 3741. This galaxy has a very extended gas disk (~8.8 times the Holmberg radius), and a dark to luminous (i.e. stellar) mass ratio of ~149, which makes it one of the ``darkest'' dwarf ... More
An H-alpha Imaging Survey of Galaxies in the Local 11 Mpc VolumeJul 13 2008As part of a broader effort to characterize the population of star-forming galaxies in the local universe, we have carried out an H-alpha+[NII] imaging survey for an essentially volume-limited sample of galaxies within 11 Mpc of the Milky Way. This paper ... More
HI Properties of Low Luminosity Star-Forming Galaxies in the KPNO International Spectroscopic SurveyAug 27 2002New HI observations are presented for a complete sample of 109 low luminosity star-forming galaxies taken from the KPNO International Spectroscopic Survey (KISS), the first CCD-based wide-field objective-prism survey for emission-line galaxies. This sample ... More
A New Method for Measuring the Upper End of the IMFOct 24 2010A method is presented here for investigating variations in the upper end of the stellar Initial Mass Function (IMF) by probing the production rate of ionizing photons in unresolved, compact star clusters with ages<10 Myr and covering a range of masses. ... More
Visualizing the invisible the relentless pursuit of MTech ImagingJun 04 2016This teaching case describes the challenges faced by MTech Imaging, a Singapore small and medium enterprise (SME) that specializes in providing thermal imaging solutions. In recent years, the company has relentlessly strived to become a digital innovative ... More
Robust and fully automated segmentation of mandible from CT scansFeb 23 2017Mandible bone segmentation from computed tomography (CT) scans is challenging due to mandible's structural irregularities, complex shape patterns, and lack of contrast in joints. Furthermore, connections of teeth to mandible and mandible to remaining ... More
First Spectroscopic Evidence for High Ionization State and Low Oxygen Abundance in Lya EmittersAug 16 2012Mar 21 2013We present results from Keck/NIRSPEC and Magellan/MMIRS follow-up spectroscopy of Lya emitters (LAEs) at z=2.2 identified in our Subaru narrowband survey. We successfully detect Ha emission from seven LAEs, and perform a detailed analysis of six LAEs ... More
Hubble Space Telescope Grism Spectroscopy of Extreme Starbursts Across Cosmic Time: The Role of Dwarf Galaxies in the Star Formation History of the UniverseJun 16 2014Near infrared slitless spectroscopy with the Wide Field Camera 3, onboard the Hubble Space Telescope, offers a unique opportunity to study low-mass galaxy populations at high-redshift ($z\sim$1-2). While most high$-z$ surveys are biased towards massive ... More
Star Cluster Properties in Two LEGUS Galaxies Computed with Stochastic Stellar Population Synthesis ModelsSep 16 2015We investigate a novel Bayesian analysis method, based on the Stochastically Lighting Up Galaxies (slug) code, to derive the masses, ages, and extinctions of star clusters from integrated light photometry. Unlike many analysis methods, slug correctly ... More
Nebular Attenuation in Hα-selected Star-forming Galaxies at z=0.8 from the NewHα SurveyJul 23 2012We present measurements of the dust attenuation of H\alpha-selected emission-line galaxies at z=0.8 from the NewH\alpha\ narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong rest-frame ... More
Mach-Zehnder Interferometry in a Strongly Driven Superconducting QubitDec 29 2005We demonstrate Mach-Zehnder-type interferometry in a superconducting flux qubit. The qubit is a tunable artificial atom, whose ground and excited states exhibit an avoided crossing. Strongly driving the qubit with harmonic excitation sweeps it through ... More
A Critical Look at the Mass-Metallicity-SFR Relation in the Local Universe. I. An Improved Analysis Framework and Confounding SystematicsNov 26 2014Dec 20 2014It has been proposed that the mass-metallicity relation of galaxies exhibits a secondary dependence on star formation rate (SFR), and that the resulting M-Z-SFR relation may be redshift-invariant, i.e., "fundamental." However, conflicting results on the ... More
The Recent Star Formation Histories of M81 Group Dwarf Irregular GalaxiesSep 29 2008We present observations and analysis of nine dwarf irregular galaxies (dIs) in the M81 Group taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. The nine galaxy sample (the Garland, M81 Dwarf A, DDO 53, Ho IX, Ho I, DDO 165, ... More
The H-alpha Luminosity Function and Star Formation Rate Volume Density at z=0.8 from the NEWFIRM H-alpha SurveyNov 11 2010Jun 27 2011[Abridged] We present new measurements of the H-alpha luminosity function (LF) and SFR volume density for galaxies at z~0.8. Our analysis is based on 1.18$\mu$m narrowband data from the NEWFIRM H-alpha Survey, a comprehensive program designed to capture ... More
Chemical Abundances of Seven Irregular and Three Tidal Dwarf Galaxies in the M81 GroupOct 16 2009Nov 04 2009We have derived nebular abundances for 10 dwarf galaxies belonging to the M81 Group, including several galaxies which do not have abundances previously reported in the literature. For each galaxy, multiple H \ii regions were observed with GMOS-N at the ... More
Communicative Competence for Individuals who require Augmentative and Alternative Communication: A New Definition for a New Era of Communication?Nov 03 2014In 1989, Light defined communicative competence for individuals with complex communication needs who require augmentative and alternative communication (AAC) as a dynamic, interpersonal construct based on functionality of communication, adequacy of communication, ... More
On the Thom-Boardman Symbols for Polynomial Multiplication MapsFeb 09 2009The Thom-Boardman symbol was first introduced by Thom in 1956 to classify singularities of differentiable maps. It was later generalized by Boardman to a more general setting. Although the Thom-Boardman symbol is realized by a sequence of non-increasing, ... More
Stellar Populations of Lyman Alpha Emitters at z = 3 - 4 Based on Deep Large Area Surveys in the Subaru-SXDS/UKIDSS-UDS FieldNov 13 2009We investigate the stellar populations of Lyman alpha emitters (LAEs) at z=3.1 and 3.7 in 0.65 deg^2 of the Subaru/XMM-Newton Deep Field, based on rest-frame UV-to-optical photometry obtained from the Subaru/XMM-Newton Deep Survey, the UKIDSS/Ultra Deep ... More
The Relationship between Stellar Mass, Gas Metallicity, and Star Formation Rate for Halpha-selected Galaxies at z~0.8 from the NewHalpha SurveyOct 06 2014Nov 11 2014Using a sample of 299 Ha-selected galaxies at z~0.8, we study the relationship between galaxy stellar mass, gas-phase metallicity, and star formation rate (SFR), and compare to previous results. We use deep optical spectra obtained with the IMACS spectrograph ... More
The Spitzer Local Volume Legacy (LVL) Global Optical PhotometryAug 05 2014We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D < 11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < M_B < -20.7 mag. A composite ... More
Spitzer Local Volume Legacy (LVL) SEDs and Physical PropertiesSep 02 2014We present the panchromatic spectral energy distributions (SEDs) of the Local Volume Legacy (LVL) survey which consists of 258 nearby galaxies ($D<$11 Mpc). The wavelength coverage spans the ultraviolet to the infrared (1500 $\textrm{\AA}$ to 24 $\mu$m) ... More
Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent Current QubitNov 12 2003Nov 13 2003We measured the intrawell energy relaxation time \tau_{d} between macroscopic quantum levels in the double well potential of a Nb persistent-current qubit. Interwell population transitions were generated by irradiating the qubit with microwaves. Zero ... More
Average Metallicity and Star Formation Rate of Lya Emitters Probed by a Triple Narrow-Band SurveyMay 13 2011Dec 02 2011We present the average metallicity and star-formation rate of Lya emitters (LAEs) measured from our large-area survey with three narrow-band (NB) filters covering the Lya, [OII]3727, and Ha+[NII] lines of LAEs at z=2.2. We select 919 z=2.2 LAEs from Subaru/Suprime-Cam ... More
Empirical ugri-UBVRc Transformations for GalaxiesAug 05 2014We present empirical color transformations between Sloan Digital Sky Survey ugri and Johnson-Cousins UBVRc photometry for nearby galaxies (D < 11 Mpc). We use the Local Volume Legacy (LVL) galaxy sample where there are 90 galaxies with overlapping observational ... More
A Dual Narrowband Survey for Hα Emitters at z=2.2: Demonstration of the Technique and Constraints on the Hα Luminosity FunctionApr 30 2012We present first results from a narrowband imaging program for intermediate redshift emission-line galaxies using the newly commissioned FourStar infrared camera at the 6.5m Magellan telescope. To enable prompt identification of H\alpha\ emitters, a pair ... More
The Wyoming Survey for H-alpha. III. A Multi-wavelength Look at Attenuation by Dust in Galaxies out to z~0.4Jun 11 2010We report results from the Wyoming Survey for H-alpha (WySH), a comprehensive four-square degree survey to probe the evolution of star-forming galaxies over the latter half of the age of the Universe. We have supplemented the H-alpha data from WySH with ... More
A Transition Mass in the Local Tully-Fisher RelationJun 12 2015We study the stellar mass Tully-Fisher relation (TFR, stellar mass versus rotation velocity) for a morphologically blind selection of emission line galaxies in the field at redshifts 0.1 $<$ z $<$ 0.375. Kinematics ($\sigma_g$, V$_{rot}$) are measured ... More
GALEX-SDSS-WISE Legacy Catalog (GSWLC): Star Formation Rates, Stellar Masses and Dust Attenuations of 700,000 Low-redshift GalaxiesOct 03 2016In this paper, we present GALEX-SDSS-WISE Legacy Catalog (GSWLC), a catalog of physical properties (stellar masses, dust attenuations and star formation rates (SFRs)) of ~700,000 galaxies with SDSS redshifts below 0.3. GSWLC contains galaxies within the ... More
A Convolutional Autoencoder for Multi-Subject fMRI Data AggregationAug 17 2016Finding the most effective way to aggregate multi-subject fMRI data is a long-standing and challenging problem. It is of increasing interest in contemporary fMRI studies of human cognition due to the scarcity of data per subject and the variability of ... More
A Searchlight Factor Model Approach for Locating Shared Information in Multi-Subject fMRI AnalysisSep 29 2016There is a growing interest in joint multi-subject fMRI analysis. The challenge of such analysis comes from inherent anatomical and functional variability across subjects. One approach to resolving this is a shared response factor model. This assumes ... More
A wildland fire model with data assimilationSep 02 2007Jan 15 2008A wildfire model is formulated based on balance equations for energy and fuel, where the fuel loss due to combustion corresponds to the fuel reaction rate. The resulting coupled partial differential equations have coefficients that can be approximated ... More
Measuring Galaxy Star Formation Rates From Integrated Photometry: Insights from Color-Magnitude Diagrams of Resolved StarsMay 30 2013We use empirical star formation histories (SFHs), measured from HST-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of ~50 nearby dwarf galaxies (6.5 < ... More
The M81 Group Dwarf Irregular Galaxy DDO 165. I. High Velocity Neutral Gas in a Post-Starburst SystemApr 04 2011We present new multi-configuration VLA HI spectral line observations of the M81 group dIrr post-starburst galaxy DDO 165. The HI morphology is complex, with multiple column density peaks surrounding a large region of very low HI surface density that is ... More
A GALEX Ultraviolet Imaging Survey of Galaxies in the Local VolumeSep 23 2010Nov 09 2010We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ~11 Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy (LVL), an ultraviolet-to-infrared imaging program designed ... More
Asymmetric scattering of Dirac electrons and holes in grapheneApr 23 2013The relativistic nature of Dirac electrons and holes in graphene profoundly affects the way they interact with impurities. Signatures of the relativistic behavior have been observed recently in scanning tunneling measurements on individual impurities, ... More
The M81 Group Dwarf Irregular Galaxy DDO 165. II. Connecting Recent Star Formation with ISM Structures and KinematicsApr 04 2011We compare the stellar populations and complex neutral gas dynamics of the M81 group dIrr galaxy DDO 165 using data from the HST and the VLA. Paper I identified two kinematically distinct HI components, multiple localized high velocity gas features, and ... More
Modeling the Effects of Star Formation Histories on Halpha and Ultra-Violet Fluxes in Nearby Dwarf GalaxiesSep 13 2011We consider the effects of non-constant star formation histories (SFHs) on Halpha and GALEX far ultra-violet (FUV) star formation rate (SFR) indicators. Under the assumption of a fully populated Chabrier IMF, we compare the distribution of Halpha-to-FUV ... More
The Nature of Low-Density Star FormationMar 13 2019How do stars manage to form within low-density, HI-dominated gas? Such environments provide a laboratory for studying star formation with physical conditions distinct from starbursts and the metal-rich disks of spiral galaxies where most effort has been ... More
Direct Oxygen Abundances for Low Luminosity LVL GalaxiesMay 30 2012We present MMT spectroscopic observations of HII regions in 42 low luminosity galaxies in the LVL. For 31 galaxies, we measured the temperature sensitive [O III] line at a strength of 4 sigma or greater, and thus determine direct oxygen abundances. Our ... More
LEGUS Discovery of a Light Echo Around Supernova 2012awApr 30 2015We have discovered a luminous light echo around the normal Type II-Plateau Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images obtained approximately two years after explosion with the Wide Field Channel 3 on-board the Hubble Space ... More
Quantum Interference Noise Near the Dirac Point in GrapheneJan 28 2014Effects of disorder on the electronic transport properties of graphene are strongly affected by the Dirac nature of the charge carriers in graphene. This is particularly pronounced near the Dirac point, where relativistic charge carriers cannot efficiently ... More
The Three Dimensional Structural Shape of the Gravitational Potential in the Local GroupMay 10 2006Jun 19 2008The Local Group is a small galaxy cluster with the membership of 62 nearby galaxies including the Milky Way and M31. Although the Local Group has yet to be virialized, it interacts with the surrounding matter as one gravitationally bound system. To understand ... More
Restriction estimates to complex hyper-surfacesMar 11 2019The restriction problem is better understood for hyper-surfaces and recent progresses have been made by bilinear and multilinear approaches and most recently polynomial partitioning method which is combined with those estimates. However, for surfaces ... More
Generalizations of the Choe-Hoppe helicoid and Clifford cones in Euclidean spaceOct 13 2014Oct 26 2015Our goal is to generalize the Choe-Hoppe helicoid and Clifford cones in Euclidean space. By sweeping out $L$ indpendent Clifford cones in ${\mathbb{R}}^{2N+2}$ via the multi-screw motion, we construct minimal submanifolds in ${\mathbb{R}}^{L(2N+2)+1}$. ... More
On the structure of certain valued fieldsAug 27 2016Sep 07 2018For any two complete discrete valued fields $K_1$ and $K_2$ of mixed characteristic with perfect residue fields, we show that if each pair of $n$-th residue rings is isomorphic for each $n\ge1$, then $K_1$ and $K_2$ are isometric and isomorphic. More ... More
On the structure of certain valued fieldsAug 27 2016Sep 19 2016For any two complete discrete valued fields $K_1$ and $K_2$ of mixed characteristic with perfect residue fields, we show that if each pair of $n$-th residue rings is isomorphic for each $n\ge1$, then $K_1$ and $K_2$ are isometric and isomorphic. More ... More
The Variation of Galaxy Morphological Type with the Shear of EnvironmentJan 10 2008Jul 28 2008Recent N-body simulations have shown that the assembly history of galactic halos depend on the density of large-scale environment. It implies that the galaxy properties like age and size of bulge may also vary with the surrounding large-scale structures, ... More
Reconstructing the Intrinsic Triaxial Shape of the Virgo ClusterApr 11 2007To use galaxy clusters as a cosmological probe, it is important to account for their triaxiality. Assuming that the triaxial shapes of galaxy clusters are induced by the tidal interaction with the surrounding matter, Lee and Kang recently developed a ... More
Observation of angle-dependent transmission of Dirac electrons in graphene hetero junctionsApr 19 2013Jan 28 2014The relativistic nature of charge carriers in graphene is expected to lead to an angle- dependent transmission through a potential barrier, where Klein tunneling involves annihilation of an electron and a hole at the edges of the barrier. The signatures ... More
Data Assimilation for Wildland Fires: Ensemble Kalman filters in coupled atmosphere-surface modelsDec 24 2007Jan 15 2009Two wildland fire models are described, one based on reaction-diffusion-convection partial differential equations, and one based on semi-empirical fire spread by the level let method. The level set method model is coupled with the Weather Research and ... More
Unbiased Global Optimization of Lennard-Jones Clusters for N <= 201 by Conformational Space Annealing MethodJul 29 2003We apply the conformational space annealing (CSA) method to the Lennard-Jones clusters and find all known lowest energy configurations up to 201 atoms, without using extra information of the problem such as the structures of the known global energy minima. ... More
Phonological modeling for continuous speech recognition in KoreanJul 18 1996A new scheme to represent phonological changes during continuous speech recognition is suggested. A phonological tag coupled with its morphological tag is designed to represent the conditions of Korean phonological changes. A pairwise language model of ... More
Chart-driven Connectionist Categorial Parsing of Spoken KoreanNov 29 1995While most of the speech and natural language systems which were developed for English and other Indo-European languages neglect the morphological processing and integrate speech and natural language at the word level, for the agglutinative languages ... More
State transfer with quantum side informationAug 14 2017Mar 16 2018We first consider quantum communication protocols between a sender Alice and a receiver Bob, which transfer Alice's quantum information to Bob by means of non-local resources, such as classical communication, quantum communication, and entanglement. In ... More
A New Efficient Key Management Protocol for Wireless Sensor and Actor NetworksDec 03 2009Research on sensor networks has become much more active and is currently being applied to many different fields. However since sensor networks are limited to only collecting and reporting information regarding a certain event, and requires human intervention ... More
Hierarchical Star Formation in Nearby LEGUS GalaxiesApr 24 2014Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies is studied by determining the numbers and fluxes of nested regions as a function of size from ~1 to ~200 pc, and the number as a function of flux. Two starburst dwarfs, NGC 1705 ... More
Neutral-current Hall effects in disordered grapheneApr 22 2015A non-local Hall bar geometry is used to detect neutral-current Hall effects in graphene on silicon dioxide. Disorder is tuned by the addition of Au or Ir adatoms in ultra-high vacuum. A reproducible neutral-current Hall effect is found in both as-fabricated ... More
Comparison of H-alpha and UV Star Formation Rates in the Local Volume: Systematic Discrepancies for Dwarf GalaxiesSep 29 2009(abridged) Using a complete sample of ~300 star-forming galaxies within 11 Mpc, we evaluate the consistency between star formation rates (SFRs) inferred from the far ultraviolet (FUV) non-ionizing continuum and H-alpha nebular emission, assuming standard ... More
Murasugi sums of Morse maps to the circle, Morse-Novikov numbers, and free genus of knotsAug 01 2001Murasugi sums can be defined as readily for Morse maps to the circle of (arbitrary) link complements in the 3-sphere as for fibrations over the circle of (fibered) link complements in the 3-sphere. As one application, I show that if a knot K has free ... More
Quasipositivity as an obstruction to slicenessJul 01 1993Mar 24 2000For an oriented link $L \subset S^3 = \Bd\!D^4$, let $\chi_s(L)$ be the greatest Euler characteristic $\chi(F)$ of an oriented 2-manifold $F$ (without closed components) smoothly embedded in $D^4$ with boundary $L$. A knot $K$ is {\it slice} if $\chi_s(K)=1$. ... More
Hopf plumbing, arborescent Seifert surfaces, baskets, espaliers, and homogeneous braidsOct 15 1998May 20 2000Four constructions of Seifert surfaces - Hopf plumbing, arborescent plumbing, basketry, and T-bandword handle decomposition - are described, and some interrelationships found, e.g.: arborescent Seifert surfaces are baskets; Hopf-plumbed baskets are precisely ... More
Matrix universality of gauge and gravitational dynamicsMar 20 2008Mar 21 2008A simple cubic matrix model is presented, which has truncations that, it is argued, lead at the classical level to a variety of theories of gauge fields and gravity. These include Chern-Simons theory in d=3, and BF theory and general relativity in d=4. ... More
Twistor relative localityNov 01 2013We present a version of relative locality based on the geometry of twistor space. This can also be thought of as a new kind of deformation of twistor theory based on the construction of a bundle of twistor spaces over momentum space. Locality in space-time ... More
The quantization of unimodular gravity and the cosmological constant problemApr 30 2009A quantization of unimodular gravity is described, which results in a quantum effective action which is also unimodular, ie a function of a metric with fixed determinant. A consequence is that contributions to the energy momentum tensor of the form of ... More
Scientific alternatives to the anthropic principleJul 26 2004Jul 29 2004It is explained in detail why the Anthropic Principle (AP) cannot yield any falsifiable predictions, and therefore cannot be a part of science. Cases which have been claimed as successful predictions from the AP are shown to be not that. Either they are ... More
The future of spin networksFeb 17 1997The roles that spin networks play in gauge theories, quantum gravity and topological quantum field theory are briefly described, with an emphasis on the question of the relationships among them. It is argued that spin networks and their generalizations ... More
The G_Newton --> 0 Limit of Euclidean Quantum GravityFeb 22 1992Using the Ashtekar formulation, it is shown that the G_{Newton} --> 0 limit of Euclidean or complexified general relativity is not a free field theory, but is a theory that describes a linearized self-dual connection propagating on an arbitrary anti-self-dual ... More
Towards a background independent approach to M theoryAug 31 1998Work in progress is described which aims to construct a background independent formulation of M theory by extending results about background independent states and observables from quantum general relativity and supergravity to string theory. A list of ... More
A holographic formulation of quantum general relativityAug 31 1998Oct 31 1999We show that there is a sector of quantum general relativity which may be expressed in a completely holographic formulation in terms of states and operators defined on a finite boundary. The space of boundary states is built out of the conformal blocks ... More
Linking Topological Quantum Field Theory and Nonperturbative Quantum GravityMay 17 1995Jan 30 1996Quantum gravity is studied nonperturbatively in the case in which space has a boundary with finite area. A natural set of boundary conditions is studied in the Euclidean signature theory, in which the pullback of the curvature to the boundary is self-dual ... More
Experimental Signatures of Quantum GravityMar 16 1995Jan 30 1996I review several different calculations, coming from string theory, nonperturbative quantum gravity and analyses of black holes that lead to predictions of phenomena that would uniquely be signatures of quantum gravitational effects. These include: 1) ... More
Derived Commutator Complete Algebras and Relative Koszul Duality for OperadsFeb 04 2016Oct 18 2016We prove that a connected commutator (or NC) complete associative algebra can be recovered in the derived setting from its abelianization together with its natural induced structure. Specifically, we prove an equivalence between connected derived commutator ... More
Differential Graded Categories are k-linear Stable Infinity CategoriesAug 12 2013Sep 12 2016We describe a comparison between pretriangulated differential graded categories and certain stable infinity categories. Specifically, we use a model category structure on differential graded categories over k (a field of characteristic 0) where the weak ... More
Nuclear Lattice Simulations with EFTAug 17 2004This proceedings article is a summary of results from work done in collaboration with Bugra Borasoy and Thomas Schaefer. We study nuclear and neutron matter by combining chiral effective field theory with non-perturbative lattice methods. We present results ... More
Singularities of massless planar diagrams, large-N_c mesons in 3+1 dimensions, and the 't Hooft modelDec 12 1997We study the singular Landau surfaces of planar diagrams contributing to scattering of a massless quark and antiquark in 3+1 dimensions. In particular, we look at singularities which remain after integration with respect to the various angular degrees ... More
The symmetric heavy-light ansatzApr 25 2007Feb 12 2008The symmetric heavy-light ansatz is a method for finding the ground state of any dilute unpolarized system of attractive two-component fermions. Operationally it can be viewed as a generalization of the Kohn-Sham equations in density functional theory ... More
Large-N droplets in two dimensionsDec 09 2005May 15 2006Using lattice effective field theory, we study the ground state binding energy of N distinct particles in two dimensions with equal mass interacting weakly via an attractive SU(N)-symmetric short range potential. We find that in the limit of zero range ... More
Mesons with a Light Quark-Antiquark Pair and the Bethe-Salpeter EquationSep 24 1994Sep 24 1994The light quark-antiquark scattering Green's function is considered near a meson resonance peak. The Bethe-Salpeter equation is used to write formal expressions for the resonance width/mass ratio. Arguments are made concerning to what extent this ratio ... More
A convexity theorem for real projective structuresMay 27 2007Given a finite collection P of convex n-polytopes in RP^n (n>1), we consider a real projective manifold M which is obtained by gluing together the polytopes in P along their facets in such a way that the union of any two adjacent polytopes sharing a common ... More
Towards Weakly Constrained Double Field TheorySep 23 2015We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon) transform on a torus is well-suited for describing weakly ... More
Limitation of Multipoles in BOSS DR12 resultsOct 25 2016Recently, the power spectrum (PS) multipoles using the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 (DR12) sample are analyzed \cite{160703150}. Even though the based model for the analysis is the so-called TNS quasi-linear model including ... More
Using prior information to identify boundaries in disease risk mapsAug 24 2012Disease maps display the spatial pattern in disease risk, so that high-risk clusters can be identified. The spatial structure in the risk map is typically represented by a set of random effects, which are modelled with a conditional autoregressive (CAR) ... More