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Results for "Joseph N. Burchett"

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IGM-Vis: Analyzing Intergalactic and Circumgalactic Medium Absorption Using Quasar Sightlines in a Cosmic Web ContextDec 17 2018This article introduces the Intergalactic Medium Visualization, or 'IGM-Vis', a novel visualization and data analysis platform for investigating galaxies and the gas that surrounds them in context with their larger scale environment, the Cosmic Web. Environment ... More
On the CGM Fundamental Plane: The Halo Mass Dependency of Circumgalactic HIDec 06 2017Aug 07 2018We analyze the equivalent widths of HI Ly-$\alpha$ ($W_{Ly\alpha}$) absorption from the inner (R < 160 kpc) circumgalactic medium (CGM) of 85 galaxies at $z \sim 0$ with stellar masses $M*$ ranging $\rm{8 \leq log M* / M_{\odot} \leq 11.6}$. Across three ... More
A Deep Search for Faint Galaxies Associated with Very Low-Redshift C IV Absorbers: A Case with Cold-Accretion CharacteristicsNov 18 2013Studies of QSO absorber-galaxy connections are often hindered by inadequate information on whether faint/dwarf galaxies are located near the QSO sight lines. To investigate the contribution of faint galaxies to QSO absorber populations, we are conducting ... More
Probing the dynamical state, baryon content, and multiphase nature of galaxy clusters with bright background QSOsOct 09 2018We have initiated a programme to study the physical/dynamical state of gas in galaxy clusters and the impact of the cluster environment on gaseous halos of individual galaxies using X-ray imaging and UV absorption line spectroscopy of background QSOs. ... More
The Power Spectrum of the Lyman-$α$ Forest at z < 0.5Aug 16 2018We present new measurements of the flux power-spectrum P(k) of the z<0.5 H I Lyman-$\alpha$ forest spanning scales k ~ 0.001-0.1 s/km. These results were derived from 65 far ultraviolet quasar spectra (resolution R~18,000) observed with Cosmic Origin ... More
Following the Metals in the Intergalactic and Circumgalactic Medium over Cosmic TimeMar 18 2019The circumgalactic medium (CGM) of galaxies serves as a record of the influences of outflows and accretion that drive the evolution of galaxies. Feedback from star formation drives outflows that carry mass and metals away from galaxies to the CGM, while ... More
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic MediumDec 02 2015Sep 15 2016Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C IV absorption systems and the properties of nearby galaxies as well as large-scale ... More
The COS-Halos Survey: Metallicities in the Low-Redshift Circumgalactic MediumFeb 08 2017We analyze new far-ultraviolet spectra of 13 quasars from the z~0.2 COS-Halos survey that cover the HI Lyman limit of 14 circumgalactic medium (CGM) systems. These data yield precise estimates or more constraining limits than previous COS-Halos measurements ... More
The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* GalaxiesJun 02 2014Nov 20 2014We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z $\leq$ 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected ... More
Extreme circumgalactic HI and CIII absorption around the most massive, quenched galaxiesSep 26 2018Luminous red galaxies (LRGs) are the most massive galaxies at $z\sim 0.5$ and, by selection, have negligible star formation. These objects have halo masses between those of $L_{*}$ galaxies, whose circumgalactic media (CGM) are observed to have large ... More
The COS Absorption Survey of Baryon Harbors (CASBaH): Warm-hot Circumgalactic Gas Reservoirs Traced by Ne VIII AbsorptionOct 15 2018We present a sample of 30 galaxies at 0.49 < z(gal) < 1.44 probed by Ne VIII absorption to study the highly ionized circumgalactic medium (CGM) based on high-S/N ultraviolet spectra of z > 1 QSOs and the galaxy database from the COS Absorption Survey ... More
The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas ReservoirsOct 21 2016We present the HI mass inventory for the RESOLVE survey, a volume-limited, multi-wavelength census of >1500 z=0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of 10^9 Msun. This first 21cm data release provides robust ... More
The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas ReservoirsOct 21 2016Nov 01 2016We present the HI mass inventory for the RESOLVE survey, a volume-limited, multi-wavelength census of >1500 z=0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of 10^9 Msun. This first 21cm data release provides robust ... More
Ultraviolet Perspectives on Diffuse Gas in the Largest Cosmic StructuresMar 14 2019The past decade has seen an explosion of discoveries and new insights into the diffuse gas within galaxies, galaxy clusters, and the filaments composing the Cosmic Web. A new decade will bring fresh opportunities to further this progress towards developing ... More
The Shape of Saturn's Huygens Ringlet Viewed by Cassini ISSSep 24 2015Oct 07 2015A new model for the shape of the prominent eccentric ringlet in the gap exterior to Saturn's B-ring is developed based on Cassini imaging observations taken over about 8 years. Unlike previous treatments, the new model treats each edge of the ringlet ... More
An N-body Integrator for Gravitating Planetary Rings, and the Outer Edge of Saturn's B RingJun 05 2013Jun 06 2013A new symplectic N-body integrator is introduced, one designed to calculate the global 360 degree evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely-available code is called epi_int, and it is distinct ... More
Dynamics of the Sharp Edges of Broad Planetary RingsApr 04 2009(Abridged) The following describes a model of a broad planetary ring whose sharp edge is confined by a satellite's m^th Lindblad resonance (LR). This model uses a streamline formalism to calculate the ring's internal forces, namely, ring gravity, pressure, ... More
Warm-hot Gas in X-ray Bright Galaxy Clusters and the H I-deficient Circumgalactic Medium in Dense EnvironmentsMay 16 2017Dec 12 2017We analyze the intracluster medium (ICM) and circumgalactic medium (CGM) in 7 X-ray detected galaxy clusters using spectra of background QSOs (HST-COS/STIS), optical spectroscopy of the cluster galaxies (MMT/Hectospec and SDSS), and X-ray imaging/spectroscopy ... More
Size Effects in the Ginzburg-Landau TheoryApr 22 2015The Ginzburg-Landau theory is analyzed in the case of small dimension superconductors, a couple of orders of magnitude above the coherence length, where the theory is still valid but quantum fluctuations become significant. In this regime, the potential ... More
Accelerated point-wise maximum approach to approximate dynamic programmingJan 11 2019We describe an approximate dynamic programming approach to compute lower bounds on the optimal value function for a discrete time, continuous space, infinite horizon setting. The approach iteratively constructs a family of lower bounding approximate value ... More
Fast, high-resolution surface potential measurements in air with heterodyne Kelvin probe force microscopyJan 11 2016Apr 11 2016Kelvin probe force microscopy (KPFM) adapts an atomic force microscope to measure electric potential on surfaces at nanometer length scales. Here we demonstrate that Heterodyne-KPFM enables scan rates of several frames per minute in air, and concurrently ... More
Shear Selected Cluster Cosmology I: Tomography and Optimal FilteringApr 19 2004Jan 31 2005We study the potential of weak lensing surveys to detect clusters of galaxies, using a fast Particle Mesh cosmological N-body simulation algorithm specifically tailored to investigate the statistics of these mass-selected clusters. In particular, we explore ... More
Hermitian boson mapping and finite truncationMay 23 1994Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are also finite ... More
Pseudo-scheduling: A New Approach to the Broadcast Scheduling ProblemOct 11 2012The broadcast scheduling problem asks how a multihop network of broadcast transceivers operating on a shared medium may share the medium in such a way that communication over the entire network is possible. This can be naturally modeled as a graph coloring ... More
Phenomenological correlations in high-temperature superconductorsJul 13 2014An interpretation of the quadratic parameter of the Ginzburg-Landau theory of superconductivity is presented in this paper. The negative term in the potential, which allows the spontaneous symmetry breaking, is interpreted as a direct contribution from ... More
Rgbp: An R Package for Gaussian, Poisson, and Binomial Random Effects Models with Frequency Coverage EvaluationsDec 06 2016Rgbp is an R package that provides estimates and verifiable confidence intervals for random effects in two-level conjugate hierarchical models for overdispersed Gaussian, Poisson, and Binomial data. Rgbp models aggregate data from k independent groups ... More
Understanding the circumgalactic medium is critical for understanding galaxy evolutionMar 13 2019Galaxies evolve under the influence of gas flows between their interstellar medium and their surrounding gaseous halos known as the circumgalactic medium (CGM). The CGM is a major reservoir of galactic baryons and metals, and plays a key role in the long ... More
MASON: A Model AgnoStic ObjectNess FrameworkSep 20 2018This paper proposes a simple, yet very effective method to localize dominant foreground objects in an image, to pixel-level precision. The proposed method 'MASON' (Model-AgnoStic ObjectNess) uses a deep convolutional network to generate category-independent ... More
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: II. Program Design, Absorption-line Measurements, and Absorber StatisticsOct 05 2015To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium (CGM), we have conducted a blind survey for C IV absorption systems in 89 QSO sightlines ... More
Capture and isolation of highly-charged ions in a unitary Penning trapDec 02 2013We recently used a compact Penning trap to capture and isolate highly-charged ions extracted from an electron beam ion trap (EBIT) at the National Institute of Standards and Technology (NIST). Isolated charge states of highly-stripped argon and neon ions ... More
The Red Dead Redemption Survey of Circumgalactic Gas About Massive Galaxies. I. Mass and Metallicity of the Cool PhaseNov 26 2018We present a search for HI in the circumgalactic medium (CGM) of 21 massive ($\langle \log M_\star \rangle \sim 11.4$), luminous red galaxies (LRGs) at $z\sim0.5$. Using UV spectroscopy of QSO sightlines projected within 500 kpc ($\sim R_{\rm vir}$) of ... More
Avoided Critical Behavior in O(n) SystemsAug 31 1998Oct 12 1998Long-range frustrating interactions, even if their strength is infinitesimal, can give rise to a dramatic proliferations of ground or near-ground states. As a consequence, the ordering temperature can exhibit a discontinuous drop as a function of the ... More
Absence of Scaling in the Integer Quantum Hall EffectJun 18 1998Jun 24 1998We have studied the conductivity peak in the transition region between the two lowest integer Quantum Hall states using transmission measurements of edge magnetoplasmons. The width of the transition region is found to increase linearly with frequency ... More
Analysis of Computer Experiments with Functional ResponseNov 07 2012This paper is motivated by a computer experiment conducted for optimizing residual stresses in the machining of metals. Although kriging is widely used in the analysis of computer experiments, it cannot be easily applied to model the residual stresses ... More
Recipe theorems for polynomial invariants on ribbon graphs with half-edgesOct 26 2014We provide recipe theorems for the Bollob\`as and Riordan polynomial $\mathcal{R}$ defined on classes of ribbon graphs with half-edges introduced in arXiv:1310.3708[math.GT]. We also define a generalized transition polynomial $Q$ on this new category ... More
Embedding Half-Edge Graphs in Punctured SurfacesAug 29 2017Sep 05 2017It is known that graphs cellularly embedded into surfaces are equivalent to ribbon graphs. In this work, we generalize this statement to broader classes of graphs and surfaces. Half-edge graphs extend abstract graphs and are useful in quantum field theory ... More
Using Humanoid Robot to Instruct and Evaluate Performance of a Physical TaskMay 06 2018In this paper, we present a tool to assess users ability to change tasks. To do this, we use a variation of the Box and Blocks Test. In this version, a humanoid robot instructs a user to perform a task involving the movement of certain colored blocks. ... More
Highly Charged Ions in Rare Earth Permanent Magnet Penning TrapsJul 13 2012A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted ... More
The Central Component of Gravitational Lens Q0957+561Jan 25 2008In 1981, a faint radio source (G') was detected near the center of the lensing galaxy of the famous "twin quasar" Q0957+561. It is still unknown whether this central radio source is a third quasar image or an active nucleus of the lensing galaxy, or a ... More
Black Holes and Galactic Density Cusps : From Black Hole to BulgeNov 12 2009Nov 12 2010Aims. In this paper we continue our study of density cusps that may contain central black holes. Methods. We recall our attempts to use distribution functions with a memory of self-similar relaxation, but mostly they apply only in restricted regions of ... More
Black holes and Galactic density cusps -- I. Radial orbit cusps and bulgesNov 12 2009Mar 20 2011In this paper, we study the distribution functions that arise naturally during self-similar radial infall of collisionless matter. Such matter may be thought of either as stars or as dark matter particles. If a rigorous steady state is assumed, then the ... More
Symmetries and Decoherence of Two-Component Confined Atomic Clouds: Study of the Atomic Echo in the two-component Bose-Einstein CondensateJun 28 2001Jul 12 2001Implications of the internal symmetries on the dynamics of the trapped two-component atomic vapors are discussed. In the cases of $^{87}$Rb (bosons) as well as of $^{40}$K (fermions) trapped in the two hyperfine states, the intrinsic $su(2)$ symmetry ... More
A New System of Parallel Isolated Nonthermal Filaments Near the Galactic Center: Evidence for a Local Magnetic Field GradientAug 22 2001We report the discovery of a system of isolated nonthermal filaments approximately 0.5 deg. northwest (75 pc in projection) of Sgr A. Unlike other isolated nonthermal filaments which show subfilamentation, braiding of subfilaments, and flaring at their ... More
Convergence of Nearest Neighbor Pattern Classification with Selective SamplingSep 06 2013In the panoply of pattern classification techniques, few enjoy the intuitive appeal and simplicity of the nearest neighbor rule: given a set of samples in some metric domain space whose value under some function is known, we estimate the function anywhere ... More
Can coarse-graining introduce long-range correlations in a symbolic sequence?Sep 02 2004We present an exactly solvable mean-field-like theory of correlated ternary sequences which are actually systems with two independent parameters. Depending on the values of these parameters, the variance on the average number of any given symbol shows ... More
Penning traps with unitary architecture for storage of highly charged ionsFeb 28 2012Penning traps are made extremely compact by embedding rare-earth permanent magnets in the electrode structure. Axially-oriented NdFeB magnets are used in unitary architectures that couple the electric and magnetic components into an integrated structure. ... More
The effect of patch potentials in Casimir force measurements determined by heterodyne Kelvin probe force microscopySep 17 2014Measurements of the Casimir force require the elimination of electrostatic interactions between the surfaces. However, due to electrostatic patch potentials, the voltage required to minimize the total force may not be sufficient to completely nullify ... More
Beyond the Damping Tail: Cross-Correlating the Kinetic Sunyaev-Zel'dovich Effect with Cosmic ShearSep 11 2003Sep 16 2003Secondary anisotropies of the CMB have the potential to reveal intricate details about the history of our universe between the present and recombination epochs. However, because the CMB we observe is the projected sum of a multitude of effects, the interpretation ... More
Atomic Convolutional Networks for Predicting Protein-Ligand Binding AffinityMar 30 2017Empirical scoring functions based on either molecular force fields or cheminformatics descriptors are widely used, in conjunction with molecular docking, during the early stages of drug discovery to predict potency and binding affinity of a drug-like ... More
On the Location and Composition of the Dust in the MCG-6-30-15 Warm AbsorberAug 01 2003Hubble Space Telescope images of MCG-6-30-15 show a dust lane crossing the galaxy just below the nucleus. In this paper, we argue that this dust lane is responsible for the observed reddening of the nuclear emission and the Fe I edge hinted at in the ... More
A Polynomial Invariant for Rank 3 Weakly-Colored Stranded GraphsJan 09 2013Apr 01 2013The Bollobas-Riordan polynomial [Math. Ann. 323, 81 (2002)] is a universal polynomial invariant for ribbon graphs. We find an extension of this polynomial for a particular family of graphs called rank 3 weakly-colored stranded graphs. These graphs live ... More
Recurrent Exponential-Family Harmoniums without Backprop-Through-TimeMay 19 2016Exponential-family harmoniums (EFHs), which extend restricted Boltzmann machines (RBMs) from Bernoulli random variables to other exponential families (Welling et al., 2005), are generative models that can be trained with unsupervised-learning techniques, ... More
The zero-energy state in graphene in a high magnetic fieldAug 14 2007Dec 05 2007The fate of the charge-neutral Dirac point in graphene in a high magnetic field $H$ has been investigated at low temperatures ($T\sim$ 0.3 K). In samples with small $V_0$ (the gate voltage needed to access the Dirac point), the resistance $R_0$ at the ... More
A Performance Estimator for Quantum Annealers: Gauge selection and Parameter SettingMar 03 2015With the advent of large-scale quantum annealing devices, several challenges have emerged. For example, it has been shown that the performance of a device can be significantly affected by several degrees of freedom when programming the device; a common ... More
Complex dynamics and development of behavioural individualityMar 22 2018Behavioural differences may arise in the absence of genetic or environmental variation. Chaotic dynamics may influence behavioural development, and so this among-individual variation. We discuss methods and experimental designs to test this idea. Ultimately, ... More
Classes of f-Deformed Landau Operators: Nonlinear Noncommutative Coordinates from Algebraic RepresentationsDec 03 2008We consider, in a superspace, new operator dependent noncommutative (NC) geometries of the nonlinear quantum Hall limit related to classes of f-deformed Landau operators in the spherical harmonic well. Different NC coordinate algebras are determined using ... More
Universality for polynomial invariants on ribbon graphs with flagsOct 14 2013In this paper, we analyze the Bollobas and Riordan polynomial for ribbon graphs with flags introduced in arXiv:1301.1987 and prove its universality. We also show that this polynomial can be defined on some equivalence classes of ribbon graphs involving ... More
Extending Tutte and Bollobás-Riordan Polynomials to Rank 3 Weakly-Colored Stranded GraphsJan 09 2013Aug 24 2017The Bollob\'as-Riordan polynomial [Math. Ann. 323, 81 (2002)] is a universal polynomial invariant for ribbon graphs. We find an extension of this polynomial for a particular family of combinatorial objects called rank 3 weakly-colored stranded graphs. ... More
A study on the curling number of graph classesDec 03 2015Jun 21 2016Given a finite nonempty sequence $S$ of integers, write it as $XY^k$, consisting of a prefix $X$ (which may possibly be empty), followed by $k$ copies of a non-empty string $Y$. Then, the greatest such integer $k$ is called the curling number of $S$ and ... More
Measurement of the Kr XVIII 3d $^2D_{5/2}$ lifetime at low energy in a unitary Penning trapApr 24 2014A different technique is used to study the radiative decay of a metastable state in multiply ionized atoms. With use of a unitary Penning trap to selectively capture Kr$^{17+}$ ions from an ion source at NIST, the decay of the 3d $^2D_{5/2}$ metastable ... More
Gemini H-band imaging of the field of a z=10 candidateSep 21 2004We present a deep H-band image of the field of a candidate z=10 galaxy magnified by the foreground (z=0.25) cluster A1835. The image was obtained with NIRI on Gemini North to better constrain the photometry and investigate the morphology of the source. ... More
Centrifugal Effects in a Bose-Einstein CondensateJul 17 1996Single particle states in the atomic trap employing the rotating magnetic field are found using the full time-dependent instantaneous trapping potential. These states are compared with those of the effective time-averaged potential. We show that the trapping ... More
Magnetism in C60 Films Induced by Proton IrradiationMar 13 2005Mar 22 2005It is shown that polycrystalline fullerene thin films on hydrogen passivated Si(111) substrates irradiated by 2 MeV protons displays ferromagnetic-like behavior at 5 K. At 300 K both the pristine and the irradiated film show diamagnetic behavior. Magnetization ... More
The Exploration of the UnknownOct 08 2004Nov 26 2004The Square Kilometre Array is conceived as a telescope which will both test fundamental physical laws and transform our current picture of the Universe. However, the scientific challenges outlined in this book are today's problems--will they still be ... More
RE L$_{3}$ X-ray absorption study of REO$_{1-x}$F$_{x}$FeAs (RE=La, Pr, Nd, Sm) oxypnictidesOct 12 2009Rare-earth L$_{3}$-edge X-ray absorption near edge structure (XANES) spectroscopy has been used to study REOFeAs (RE=La, Pr, Nd, Sm) oxypnictides. The Nd L$_{3}$ XANES due to 2p$_{3/2}\to5\epsilon$d transition shows a substantial change in both white ... More
The Radio Wavelength Time Delay of Gravitational Lens 0957+561Jul 11 1998The gravitational lens 0957+561 was monitored with the Very Large Array from 1979 to 1997. The 6 cm light curve data from 1995-1997 and the 4 cm data from 1990-1997 are reported here. At 4 cm, the intrinsic source variations occur earlier and are twice ... More
Modeling the dynamics of hypoxia inducible factor-1α (HIF-1α) within single cells and 3D cell culture systemsSep 17 2014Sep 22 2014HIF (Hypoxia Inducible Factor) is an oxygen-regulated transcription factor that mediates the intracellular response to hypoxia in human cells. There is increasing evidence that cell signaling pathways encode temporal information, and thus cell fate may ... More
Detection of Sagittarius A* at 330 MHz with the Very Large ArrayDec 08 2003We report the detection of Sagittarius A*, the radio source associated with our Galaxy's central massive black hole, at 330 MHz with the Very Large Array. Implications for the spectrum and emission processes of Sagittarius A* are discussed and several ... More
Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destructionFeb 28 2014Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T > 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in ... More
New Nonthermal Filaments at the Galactic Center: Are They Tracing a Globally Ordered Magnetic Field?Feb 03 2004New high-resolution, wide-field 90 cm VLA observations of the Galactic Center region by Nord et al. have revealed twenty nonthermal filament (NTF) candidates. We report 6 cm polarization observations of six of these. All of the candidates have the expected ... More
Sensitivity and accuracy of Casimir force measurements in airNov 17 2018Quantum electrodynamic fluctuations cause an attractive force between metallic surfaces. At separations where the finite speed of light affects the interaction, it is called the Casimir force. Thermal motion determines the fundamental sensitivity limits ... More
Long term Ultra-Violet Variability of Seyfert galaxiesOct 13 2018Flux variability is one of the defining characteristics of Seyfert galaxies, a class of active galactic nuclei (AGN). Though these variations are observed over a wide range of wavelengths, results on their flux variability characteristics in the ultra-violet ... More
Possible Evidence for MeV Dark Matter In Dwarf SpheroidalsNov 06 2003Nov 29 2004It has been recently proposed that the observed 511 keV emission from the Galactic bulge could be the product of very light (1-100 MeV) annihilating dark matter particles. Other possible explanations for this signal are associated with stellar objects, ... More
A Quantum Annealing Approach for Fault Detection and Diagnosis of Graph-Based SystemsJun 30 2014Oct 02 2014Diagnosing the minimal set of faults capable of explaining a set of given observations, e.g., from sensor readouts, is a hard combinatorial optimization problem usually tackled with artificial intelligence techniques. We present the mapping of this combinatorial ... More
The 6 cm Light Curves of B0957+561, 1979-1994: New Features and Implications for the Time DelayJul 16 1996Nov 26 1996We report on 15 years of VLA monitoring of the gravitational lens B0957+561 at 6 cm. Since our last report in 1992, there have been 32 additional observations, in which both images have returned to their quiescent flux density levels and the A image has ... More
Investigating Galactic supernova remnant candidates with LOFARJun 27 2017May 09 2018We investigate six supernova remnant (SNR) candidates --- G51.21+0.11, G52.37-0.70, G53.07+0.49, G53.41+0.03, G53.84-0.75, and the possible shell around G54.1-0.3 --- in the Galactic Plane using newly acquired LOw-Frequency ARray (LOFAR) High-Band Antenna ... More
New Variable Stars in the Globular Cluster NGC 6584May 04 2012Using the Southeastern Association for Research in Astronomy 0.6 meter telescope located at Cerro Tololo, we searched for variable stars in the southern globular cluster NGC 6584. We obtained images during 8 nights between 28 May and 6 July of 2011. After ... More
Rapid, Machine-Learned Resource Allocation: Application to High-redshift GRB Follow-upDec 15 2011As the number of observed Gamma-Ray Bursts (GRBs) continues to grow, follow-up resources need to be used more efficiently in order to maximize science output from limited telescope time. As such, it is becoming increasingly important to rapidly identify ... More
Distributed Gradient Descent in Bacterial Food SearchApr 11 2016Communication and coordination play a major role in the ability of bacterial cells to adapt to ever changing environments and conditions. Recent work has shown that such coordination underlies several aspects of bacterial responses including their ability ... More
Some New Results on the Curling Number of GraphsOct 01 2015Aug 09 2016Let $S=S_1S_2S_3\ldots S_n$ be a finite string. Write $S$ in the form $XYY\ldots Y=XY^k$, consisting of a prefix $X$ (which may be empty), followed by $k$ copies of a non-empty string $Y$. Then, the greatest value of this integer $k$ is called the curling ... More
X-ray absorption spectroscopy characterization of iron-oxide nanoparticles synthesized by high temperature plasma processingJan 15 2014Iron-oxide nanoparticles have been synthesized by high temperature arc plasma route with different plasma currents and characterized for their structure, morphology and local atomic order. Fe K-edge x-ray absorption spectra reveal distinct local structure ... More
Complex diffusion-weighted image estimation via matrix recovery under general noise modelsDec 14 2018We propose a patch-based singular value shrinkage method for diffusion magnetic resonance image estimation targeted at low signal to noise ratio and accelerated acquisitions. It operates on the complex data resulting from a sensitivity encoding reconstruction, ... More
Action potential restitution and hysteresis in a reaction-diffusion system with pacing rate dependent excitation thresholdMay 28 2008Aug 14 2008We have demonstrated that rate dependent restitution and action potential duration-refractory period hysteresis can be reproduced in a one-dimensional two-variable Chernyak-Starobin-Cohen reaction-diffusion medium with variable excitation threshold. We ... More
Cassini imaging search rules out rings around RheaAug 10 2010We have conducted an intensive search for any material that may orbit Rhea, using images obtained by the Cassini ISS narrow-angle camera. We find no evidence for any such material, contradicting an earlier and surprising inference that Rhea, the second-largest ... More
Determination and correction of persistent biases in quantum annealersMar 19 2015Calibration of quantum computing technologies is essential to the effective utilization of their quantum resources. Specifically, the performance of quantum annealers is likely to be significantly impaired by noise in their programmable parameters, effectively ... More
Radio Recombination Lines at Decametre Wavelengths: Prospects for the FutureOct 02 2010This paper considers the suitability of a number of emerging and future instruments for the study of radio recombination lines (RRLs) at frequencies below 200 MHz. These lines arise only in low-density regions of the ionized interstellar medium, and they ... More
Mechanism for puddle formation in grapheneDec 05 2011When graphene is close to charge neutrality, its energy landscape is highly inhomogeneous, forming a sea of electron-like and hole-like puddles, which determine the properties of graphene at low carrier density. However, the details of the puddle formation ... More
Curling Numbers of Certain Graph PowersSep 01 2015Nov 17 2015Given a finite nonempty sequence $S$ of integers, write it as $XY^k$, where $Y^k$ is a power of greatest exponent that is a suffix of $S$: this $k$ is the curling number of $S$. The concept of curling number of sequences has already been extended to the ... More
Atiyah-Sutcliffe type constructions exist for all classical groupsAug 17 2015If $G$ is a compact Lie group, with Lie algebra $\mathfrak{g}$ and Weyl group $W$, and $T$ is a maximal torus of $G$, with Lie algebra $\frak{t}$, then the Berry-Robbins problem for $G$, as formulated by Sir Michael Atiyah and Roger Bielawski, asks whether ... More
Affine-compact functorsAug 15 2016May 18 2018Several well known polytopal constuctions are examined from the functorial point of view. A naive analogy between the Billera-Sturmfels fiber polytope and the abelian kernel is disproved by an infinite explicit series of polytopes. A correct functorial ... More
Convex normality of rational polytopes with long edgesDec 07 2009Dec 13 2011We introduce the property of convex normality of rational polytopes and give a dimensionally uniform lower bound for the edge lattice lengths, guaranteeing the property. As an application, we show that if every edge of a lattice d-polytope P has lattice ... More
Authentication Based Solutions to Counterfeiting of Manufactured GoodsNov 27 2015Oct 03 2016Counterfeiting of manufactured goods is presented as the theft of intellectual property, patents, copyright etc. accompanied by identity theft. The purpose of the identity theft is to facilitate the intellectual property theft. Without it the intellectual ... More
Differencing Methods for Korobov-type exponential sumsJun 25 2016We study exponential sums of the form $\sum_{n=1}^N e^{2\pi i a b^n/m}$ for non-zero integers $a,b,m$. Classically, non-trivial bounds were known for $N\ge \sqrt{m}$ by Korobov, and this range has been extended significantly by Bourgain as a result of ... More
Absolutely abnormal, continued fraction normal numbersDec 01 2015In this short note, we give a proof, conditional on the Generalized Riemann Hypothesis, that there exist numbers x which are normal with respect to the continued fraction expansion but not to any base b expansion. This partially answers a question of ... More
A simpler normal number construction for simple Luroth seriesNov 19 2013Champernowne famously proved that the number $0.(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)...$ formed by concatenating all the integers one after another is normal base 10. We give a generalization of Champernowne's construction to various other digit systems, ... More
On sigma-finite measures related to the Martin boundary of recurrent Markov chainsNov 07 2014In our monograph with B. Roynette and M. Yor, we construct a sigma-finite measure related to penalisations of different stochastic processes, including the Brownian motion in dimension 1 or 2, and a large class of linear diffusions. In the last chapter ... More
Quantum Versus Mean Field Behavior of Normal Modes of a Bose-Einstein Condensate in a Magnetic TrapNov 26 1996Nov 27 1996Quantum evolution of a collective mode of a Bose-Einstein condensate containing a finite number N of particles shows the phenomena of collapses and revivals. The characteristic collapse time depends on the scattering length, the initial amplitude of the ... More
Energy dependent sputtering of nano-clusters from a nanodisperse target and embedding of nanoparticles into a substrateFeb 28 2005Au nanoparticles, prepared by thermal evaporation under high vacuum condition on Si substrate, are irradiated with Au ions at different ion energies. During ion irradiation, embedding of nanoparticles as well as ejection of nano-clusters is observed. ... More
A unifying representation for a class of dependent random measuresNov 20 2012We present a general construction for dependent random measures based on thinning Poisson processes on an augmented space. The framework is not restricted to dependent versions of a specific nonparametric model, but can be applied to all models that can ... More
Persistence-infectivity trade-offs in environmentally transmitted pathogens change population-level disease dynamicsFeb 15 2018Human pathogens transmitted through environmental pathways are subject to stress and pressures outside of the host. These pressures may cause pathogen pathovars to diverge in their environmental persistence and their infectivity on an evolutionary time-scale. ... More