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Stimulating STDP to Exploit Locality for Lifelong Learning without Catastrophic ForgettingFeb 08 2019Stochastic gradient descent requires that training samples be drawn from a uniformly random distribution of the data. For a deployed system that must learn online from an uncontrolled and unknown environment, the ordering of input samples often fails ... More

ASP: Learning to Forget with Adaptive Synaptic Plasticity in Spiking Neural NetworksMar 22 2017Jun 08 2018A fundamental feature of learning in animals is the "ability to forget" that allows an organism to perceive, model and make decisions from disparate streams of information and adapt to changing environments. Against this backdrop, we present a novel unsupervised ... More

Electron doped Ca10(Pt3As8)(Fe2As2)5 and Ca10(Pt4As8)(Fe2As2)5 - High Tc superconductors with skutterudite intermediary layersJun 10 2011It has been argued that the very high transition temperatures of the highest Tc cuprate superconductors are facilitated by enhanced CuO2 plane coupling through the (Bi,Tl,Hg)-O intermediary layers. Whether enhanced coupling through intermediary layers ... More

Near-Ultraviolet Spectra of Flares on YZ CMiNov 02 2006Near-ultraviolet spectroscopic data obtained with the HST STIS instrument on the dMe flare star YZ Canis Minoris (YZ CMi) were analyzed. Flare and quiet intervals were identified from the broadband near-UV light curve, and the spectrum of each flare was ... More

Forward Modeling of Synthetic EUV/SXR Emission from Solar Coronal Active Regions: Case of AR 11117Sep 12 2014Recent progress in obtaining high spatial resolution images of the solar corona in the extreme-ultraviolet (EUV) with Hinode, TRACE, SDO and recent Hi-C missions and soft X-ray (SXR) bands opened a new avenue in understanding the solar coronal heating, ... More

Investigating the response of loop plasma to nanoflare heating using RADYN simulationsApr 16 2018We present the results of 1D hydrodynamic simulations of coronal loops which are subject to nanoflares, caused by either in-situ thermal heating, or non-thermal electrons (NTE) beams. The synthesized intensity and Doppler shifts can be directly compared ... More

Solar Ellerman Bombs in 1-D Radiative HydrodynamicsJan 16 2017Recent observations from the Interface Region Imaging Spectrograph (IRIS) appear to show impulsive brightenings in high temperature lines, which when combined with simultaneous ground based observations in H$\alpha$, appear co-spatial to Ellerman Bombs ... More

Radiative Hydrodynamic Models of the Optical and Ultraviolet Emission from Solar FlaresJul 13 2005We report on radiative hydrodynamic simulations of moderate and strong solar flares. The flares were simulated by calculating the atmospheric response to a beam of non-thermal electrons injected at the apex of a one-dimensional closed coronal loop, and ... More

From Radio to X-ray: Flares on the dMe Flare Star EV LacertaeNov 09 2004We present the results of a campaign to observe flares on the M dwarf flare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet spectroscopic, and ... More

From Radio to X-ray: The Quiescent Atmosphere of the dMe Flare Star EV LacertaeApr 11 2006We report on multi-wavelength observations spanning radio to X-ray wavelengths of the M dwarf flare star, EV Lacertae, probing the characteristics of the outer atmospheric plasma from the upper chromosphere to the corona. We detect the star at a wavelength ... More

Brownmillerite Ca2Co2O5: Synthesis, Stability, and Re-entrant Single-Crystal-to-Single-Crystal Structural TransitionsNov 20 2014Ca2Co2O5 in the brownmillerite form was synthesized using a high-pressure optical-image floating zone furnace, and single crystals with dimensions up to 1.4x0.8x0.5 mm3 were obtained. At room temperature, Ca2Co2O5 crystallizes as a fully ordered brownmillerite ... More

Complete Analysis of a Random Forest ModelMay 07 2018Sep 21 2018Random forests have become an important tool for improving accuracy in regression problems since their popularization by [Breiman, 2001] and others. In this paper, we revisit a random forest model originally proposed by [Breiman, 2004] and later studied ... More

Parameterizations of Chromospheric Condensations in dG and dMe Model Flare AtmospheresNov 26 2017The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic simulations in 1D have shown that high energy deposition ... More

Anisotropic $H_{c2}$ determined up to 92 T and the signature of multi-band superconductivity in Ca$_{10}$(Pt$_{4}$As$_{8}$)((Fe$_{1-x}$Pt$_{x}$)$_{2}$As$_{2}$)$_{5}$ superconductorFeb 22 2012The upper critical fields, $H_{c2}$($T$), of single crystals of the superconductor Ca$_{10}$(Pt$_{4-\delta}$As$_{8}$)((Fe$_{0.97}$Pt$_{0.03}$)$_{2}$As$_{2}$)$_{5}$ ($\delta$ $\approx$ 0.246) are determined over a wide range of temperatures down to $T$ ... More

Symmetry of re-entrant tetragonal phase in Ba1-xNaxFe2As2: Magnetic versus orbital ordering mechanismSep 18 2014Magneto-structural phase transitions in Ba1-xAxFe2As2 (A = K, Na) materials are discussed for both magnetically and orbitally driven mechanisms, using a symmetry analysis formulated within the Landau theory of phase transitions. Both mechanisms predict ... More

Bi2Te1.6S1.4 - a Topological Insulator in the Tetradymite FamilyMay 14 2012We describe the crystal growth, crystal structure, and basic electrical properties of Bi2Te1.6S1.4, which incorporates both S and Te in its Tetradymite quintuple layers in the motif -[Te0.8S0.2]-Bi-S-Bi-[Te0.8S0.2]-. This material differs from other Tetradymites ... More

Bulk Intergrowth of a Topological Insulator with a Room Temperature FerromagnetFeb 22 2012We demonstrate that the layered room temperature ferromagnet Fe7Se8 and the topological insulator Bi2Se3 form crystallographically oriented bulk composite intergrowth crystals. The morphology of the intergrowth in real space and reciprocal space is described. ... More

Nonparametric Bayesian Modeling for Automated Database Schema MatchingJul 06 2015The problem of merging databases arises in many government and commercial applications. Schema matching, a common first step, identifies equivalent fields between databases. We introduce a schema matching framework that builds nonparametric Bayesian models ... More

Coincident structural and magnetic order in BaFe$_2$(As$_{1-x}$)P$_x$)$_2$ revealed by high-resolution neutron diffractionOct 09 2014We present neutron diffraction analysis of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ over a wide temperature (10 to 300 K) and compositional ($0.11 \leq x \leq 0.79$) range, including the normal state, the magnetically ordered state, and the superconducting state. ... More

A Measure of Control for Secondary Cytokine-Induced Injury of Articular Cartilage: A Computational StudyJul 24 2013In previous works, the author and collaborators establish a mathematical model for injury response in articular cartilage. In this paper we use mathematical software and computational techniques, applied to an existing model to explore in more detail ... More

Charge ordering and ferrimagnetism in the strongly correlated $β$-V$_2$PO$_5$ single crystalDec 28 2017A combined study of transport, thermodynamic, neutron diffraction, nuclear magnetic resonance measurements and first principles calculation were performed for $\beta$-V$_2$PO$_5$ single crystal. It was shown to be a semiconductor with a band gap of 0.48 ... More

Tetragonal magnetic phase in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ from x-ray and neutron diffractionMay 06 2015Combined neutron and x-ray diffraction experiments demonstrate the formation of a low-temperature minority tetragonal phase in Ba$_{0.76}$K$_{0.24}$Fe$_2$As$_2$ in addition to the majority magnetic, orthorhombic phase. A coincident enhancement in the ... More

Geometric Solutions for the Neutrino Oscillation Length ResonanceApr 02 1999We give a geometric interpretation of the neutrino 'oscillation length resonance' recently discovered by Petcov. We use this picture to identify two new solutions for oscillation length resonances in a 3-layer earth model.

A 3D Model of AR 11726 Heated by NanoflaresJul 02 2018The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) and the Hinode/ EUV Imaging Spectrometer (EIS) observed AR 11726 on 2013 April 23. We present intensity images in numerous atomic lines constructed from these observations. These lines are ... More

Double-Q spin-density wave in iron arsenide superconductorsMay 22 2015Elucidating the nature of the magnetic ground state of iron-based superconductors is of paramount importance in unveiling the mechanism behind their high temperature superconductivity. Until recently, it was thought that superconductivity emerges only ... More

Estimates of Stellar Weak Interaction Rates for Nuclei in the Mass Range A=65-80Nov 12 2002We estimate lepton capture and emission rates, as well as neutrino energy loss rates, for nuclei in the mass range A=65-80. These rates are calculated on a temperature/density grid appropriate for a wide range of astrophysical applications including simulations ... More

Detailed magnetic and structural analysis mapping a robust magnetic C4 dome in Sr1-xNaxFe2As2Jan 21 2016The recently discovered $C_4$ tetragonal magnetic phase in hole-doped members of the iron-based superconductors provides new insights into the origin of unconventional superconductivity. Previously observed in Ba$_{1-x}A_x$Fe$_2$As$_2$ (with $A =$ K, ... More

Derivative-free optimization for parameter estimation in computational nuclear physicsJun 20 2014Sep 17 2014We consider optimization problems that arise when estimating a set of unknown parameters from experimental data, particularly in the context of nuclear density functional theory. We examine the cost of not having derivatives of these functionals with ... More

A New Connection between Central Engine Weak Physics and the Dynamics of Gamma-Ray Burst FireballsSep 10 2000Feb 13 2001We demonstrate a qualitatively new aspect of the dynamics of Gamma-Ray Burst (GRB) fireballs: the development of a substantial dispersion in the proton component in fireballs in which neutron decoupling occurs and is sufficiently pronounced. This effect ... More

Light Element Synthesis in High Entropy Relativistic Flows Associated with Gamma Ray BurstsMay 03 2002We calculate and discuss the light element freeze-out nucleosynthesis in high entropy winds and fireballs for broad ranges of entropy-per-baryon, dynamic timescales characterizing relativistic expansion, and neutron-to-proton ratios. With conditions characteristic ... More

Risk Bounds for High-dimensional Ridge Function Combinations Including Neural NetworksJul 05 2016Jul 26 2016Let $ f^{\star} $ be a function on $ \mathbb{R}^d $ satisfying a spectral norm condition. For various noise settings, we show that $ \mathbb{E}\|\hat{f} - f^{\star} \|^2 \leq v_{f^{\star}}\left(\frac{\log d}{n}\right)^{1/4} $, where $ n $ is the sample ... More

A Unified Term for Directed and Undirected Motility in Collective Cell InvasionMar 22 2012In this paper we develop mathematical models for collective cell motility. Initially we develop a model using a linear diffusion-advection type equation and fit the parameters to data from cell motility assays. This approach is helpful in classifying ... More

Finite-sample risk bounds for maximum likelihood estimation with arbitrary penaltiesDec 29 2017The MDL two-part coding $ \textit{index of resolvability} $ provides a finite-sample upper bound on the statistical risk of penalized likelihood estimators over countable models. However, the bound does not apply to unpenalized maximum likelihood estimation ... More

Minimax Lower Bounds for Ridge Combinations Including Neural NetsFeb 09 2017Estimation of functions of $ d $ variables is considered using ridge combinations of the form $ \textstyle\sum_{k=1}^m c_{1,k} \phi(\textstyle\sum_{j=1}^d c_{0,j,k}x_j-b_k) $ where the activation function $ \phi $ is a function with bounded value and ... More

Local Structure Controlling the Glass Transition in a Prototype Metal-Metalloid GlassJan 21 2019We use a structure analysis technique that quantifies cluster geometries using machine learning to identify a bicapped square antiprism (BSAP) as the nearest-neighbor cluster involved in the glass transition in Pd82Si18, a prototype metal-metalloid metallic ... More

Halpha line profile asymmetries and the chromospheric flare velocity fieldOct 07 2015The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Halpha and Ca II 8542 {\AA} lines are studied using high spatial, ... More

Can a Large Neutron Excess Help Solve the Baryon Loading Problem in Gamma-Ray Burst Fireballs?Apr 21 2000Sep 10 2000We point out that the baryon-loading problem in Gamma-Ray Burst (GRB) models can be amelioriated if a significant fraction of the baryons which inertially confine the fireball are converted to neutrons. A high neutron fraction in some circumstances can ... More

A Cyber Science Based Ontology for Artificial General Intelligence ContainmentJan 28 2018The development of artificial general intelligence is considered by many to be inevitable. What such intelligence does after becoming aware is not so certain. To that end, research suggests that the likelihood of artificial general intelligence becoming ... More

Statistical Guarantees for Estimating the Centers of a Two-component Gaussian Mixture by EMAug 07 2016Recently, a general method for analyzing the statistical accuracy of the EM algorithm has been developed and applied to some simple latent variable models [Balakrishnan et al. 2016]. In that method, the basin of attraction for valid initialization is ... More

Hubble Space Telescope Far Ultraviolet Spectroscopy of the Dwarf Nova VW Hyi in SuperoutburstMar 02 2007We obtained three consecutive HST spectroscopic observations of a single superoutburst of the dwarf nova VW Hydri. The spectra cover the beginning, middle, and end of the superoutburst. All of the spectra are dominated by strong absorption lines due to ... More

Approximation by Combinations of ReLU and Squared ReLU Ridge Functions with $ \ell^1 $ and $ \ell^0 $ ControlsJul 26 2016May 23 2018We establish $ L^{\infty} $ and $ L^2 $ error bounds for functions of many variables that are approximated by linear combinations of ReLU (rectified linear unit) and squared ReLU ridge functions with $ \ell^1 $ and $ \ell^0 $ controls on their inner and ... More

On prime non-primitive von Neumann regular algebrasMar 21 2011Let $E$ be any directed graph, and $K$ any field. We classify those graphs $E$ for which the Leavitt path algebra $L_K(E)$ is primitive. As a consequence, we obtain classes of examples of von Neumann regular prime rings which are not primitive.

Structural, Magnetic, and Superconducting Properties of Ba1-xNaxFe2As2Sep 30 2013We report the results of a systematic investigation of the phase diagram of the iron-based superconductor system, Ba1-xNaxFe2As2, from x = 0.1 to x = 1.0 using high resolution neutron and x-ray diffraction and magnetization measurements. We find that ... More

Uniform Approximation by Neural Networks Activated by First and Second Order Ridge SplinesJul 26 2016Aug 08 2016We establish sup-norm error bounds for functions that are approximated by linear combinations of first and second order ridge splines and show that these bounds are near-optimal.

Risk Bounds for High-dimensional Ridge Function Combinations Including Neural NetworksJul 05 2016Oct 29 2018Let $ f^{\star} $ be a function on $ \mathbb{R}^d $ with an assumption of a spectral norm $ v_{f^{\star}} $. For various noise settings, we show that $ \mathbb{E}\|\hat{f} - f^{\star} \|^2 \leq \left(v^4_{f^{\star}}\frac{\log d}{n}\right)^{1/3} $, where ... More

Approximation and Estimation for High-Dimensional Deep Learning NetworksSep 10 2018Sep 18 2018It has been experimentally observed in recent years that multi-layer artificial neural networks have a surprising ability to generalize, even when trained with far more parameters than observations. Is there a theoretical basis for this? The best available ... More

Single-Shot Terahertz Time-Domain Spectroscopy in Pulsed High Magnetic FieldsAug 29 2016We have developed a single-shot terahertz time-domain spectrometer to perform optical pump/terahertz probe experiments in pulsed, high magnetic fields up to 30 T. The single-shot detection scheme for measuring a terahertz waveform incorporates a reflective ... More

Single-Shot Terahertz Time-Domain Spectroscopy in Pulsed High Magnetic FieldsAug 29 2016Oct 12 2016We have developed a single-shot terahertz time-domain spectrometer to perform optical-pump/terahertz-probe experiments in pulsed, high magnetic fields up to 30 T. The single-shot detection scheme for measuring a terahertz waveform incorporates a reflective ... More

Fermi surface topology and low-lying electronic structure of a new iron-based superconductor Ca10(Pt3As8)(Fe2As2)5Oct 21 2011We report a first study of low energy electronic structure and Fermi surface topology for the recently discovered iron-based superconductor Ca10(Pt3As8)(Fe2As2)5 (the 10-3-8 phase, with Tc = 8K), via angle-resolved photoemission spectroscopy (ARPES). ... More

Holographic algorithms without matchgatesApr 02 2009The theory of holographic algorithms, which are polynomial time algorithms for certain combinatorial counting problems, yields insight into the hierarchy of complexity classes. In particular, the theory produces algebraic tests for a problem to be in ... More

On the uniqueness of promotion operators on tensor products of type A crystalsJun 19 2008May 05 2009The affine Dynkin diagram of type $A_n^{(1)}$ has a cyclic symmetry. The analogue of this Dynkin diagram automorphism on the level of crystals is called a promotion operator. In this paper we show that the only irreducible type $A_n$ crystals which admit ... More

Complexity, Statistical Risk, and Metric Entropy of Deep Nets Using Total Path VariationFeb 02 2019Feb 06 2019For any ReLU network there is a representation in which the sum of the absolute values of the weights into each node is exactly $1$, and the input layer variables are multiplied by a value $V$ coinciding with the total variation of the path weights. Implications ... More

A Unified Computational Model for Solar and Stellar FlaresJul 15 2015We present a unified computational framework which can be used to describe impulsive flares on the Sun and on dMe stars. The models assume that the flare impulsive phase is caused by a beam of charged particles that is accelerated in the corona and propagates ... More

Magnetically-Driven Suppression of Nematic Order in an Iron-Based SuperconductorMar 11 2013Feb 17 2015A theory of superconductivity in the iron-based materials requires an understanding of the phase diagram of the normal state. In these compounds, superconductivity emerges when stripe spin density wave (SDW) order is suppressed by doping, pressure or ... More

Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)Nov 11 2008Feb 02 2009The recently discovered iron arsenide superconductors, which display superconducting transition temperatures as high as 55 K, appear to share a number of general features with high-Tc cuprates, including proximity to a magnetically ordered state and robustness ... More

Observations and simulations of the Na I D1 line profiles in an M-class solar flareSep 26 2016We study the temporal evolution of the Na I D1 line profiles in the M3.9 flare SOL2014-06-11T21:03 UT, using high spectral resolution observations obtained with the IBIS instrument on the Dunn Solar Telescope combined with radiative hydrodynamic simulations. ... More

Multi-robot Dubins Coverage with Autonomous Surface VehiclesAug 07 2018In large scale coverage operations, such as marine exploration or aerial monitoring, single robot approaches are not ideal, as they may take too long to cover a large area. In such scenarios, multi-robot approaches are preferable. Furthermore, several ... More

Origins of diamond surface noise probed by correlating single spin measurements with surface spectroscopyOct 31 2018The nitrogen vacancy (NV) center in diamond exhibits spin-dependent fluorescence and long spin coherence times under ambient conditions, enabling applications in quantum information processing and sensing. NV centers near the surface can have strong interactions ... More

SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517BMar 29 2006We have mapped linearly polarized dust emission from the prestellar cores L1498 and L1517B with the James Clerk Maxwell Telescope (JCMT) using the Submillimetre Common User Bolometer Array (SCUBA) and its polarimeter SCUBAPOL at a wavelength of 850um. ... More

Theory of Rabi interaction between an infrared-active phonon and cavity-resonant modesDec 29 2006Jan 05 2007We present the theory of interaction between a polar vibration in a semiconductor and an electromagnetic mode of a surrounding cavity. Tuning the cavity frequency near the transverse optical phonon frequency couples the phonon-induced polarization field ... More

Ferromagnetic resonance phase imaging in spin Hall multilayersNov 25 2015We experimentally image the magnetic precession phase of patterned spin Hall multilayer samples to study the rf driving field vector using time-resolved anomalous Nernst effect (TRANE) microscopy. Our ferromagnetic resonance (FMR) measurements quantify ... More

On Steady State Neutrino Heated Ultra-Relativistic Winds from Compact ObjectsMar 27 2001Mar 28 2001We study steady state winds from compact objects in the regime where the wind velocity at infinity is ultra-relativistic. This may have relevance to some models of Gamma-Ray-Bursts (GRB's). Particular attention is paid to the case where neutrinos provide ... More

High Precision TOA-based Direct Localization of Multiple Sources in MultipathMay 12 2015Localization of radio frequency sources over multipath channels is a difficult problem arising in applications such as outdoor or indoor gelocation. Common approaches that combine ad-hoc methods for multipath mitigation with indirect localization relying ... More

An Assessment of the Energy Budgets of Low-Ionization Nuclear Emission RegionsJan 17 2010Using the SEDs of the weak AGNs 35 LINERs presented in a companion paper, we assess whether photoionization by the weak AGN can power the emission-line luminosities measured through the large (few-arcsecond) apertures used in ground-based spectroscopic ... More

FEMSIM+HRMC: Simulation of and Structural Refinement using Fluctuation Electron Microscopy for Amorphous MaterialsJul 14 2016FEMSIM, a Fortran code, has been developed to simulate the fluctuation electron microscopy signal, the variance, V(k), from a model atomic structure. FEMSIM has been incorporated into a hybrid-reverse Monte Carlo code that combines an embedded atom or ... More

The graphs with all but two eigenvalues equal to $-2$ or $0$Jan 21 2016Jul 08 2016We determine all graphs for which the adjacency matrix has at most two eigenvalues (multiplicities included) not equal to $-2$, or $0$, and determine which of these graphs are determined by their adjacency spectrum.

DiSPy: Implementation of Distortion Symmetry for the Nudged Elastic Band MethodOct 03 2018Dec 20 2018The nudged elastic band (NEB) method is a commonly used approach for the calculation of minimum energy pathways of kinetic processes. However, the final paths obtained rely heavily on the nature of the initially chosen path. This often necessitates running ... More

BIMA N2H+ 1-0 mapping observations of L183 -- fragmentation and spin-up in a collapsing, magnetized, rotating, pre-stellar coreJun 19 2009We have used the Berkeley-Illinois-Maryland Array (BIMA) to make deep N2H+ 1-0 maps of the pre-stellar core L183, in order to study the spatial and kinematic substructure within the densest part of the core. Three spatially and kinematically distinct ... More

Reproducing Type II White-Light Solar Flare Observations with Electron and Proton Beam SimulationsJun 01 2018We investigate the cause of the suppressed Balmer series and the origin of the white-light continuum emission in the X1.0 class solar flare on 2014 June 11. We use radiative hydrodynamic simulations to model the response of the flaring atmosphere to both ... More

Lagrangian Relaxation for MAP Estimation in Graphical ModelsSep 28 2007We develop a general framework for MAP estimation in discrete and Gaussian graphical models using Lagrangian relaxation techniques. The key idea is to reformulate an intractable estimation problem as one defined on a more tractable graph, but subject ... More

The Abundance of Interstellar NitrogenOct 15 1997Using the HST Goddard High Resolution Spectrograph (GHRS), we have obtained high S/N echelle observations of the weak interstellar N I 1160, 1161 A absorption doublet toward the stars Gamma Cas, Lambda Ori, Iota Ori, Kappa Ori, Delta Sco, and Kappa Sco. ... More

A Mathematical Framework Exhibiting the Emergence of Dynamic Expansion of Task Repertoire in \emph{Pheidole dentata}Nov 18 2015Apr 14 2016The division of labor (DOL) and task allocation among groups of ants living in a colony is thought to be highly efficient, and key to the robust survival of a colony. A great deal of experimental and theoretical work has been done toward gaining a clear ... More

Constraints and tensions in testing general relativity from Planck and CFHTLenS including intrinsic alignment systematicsJan 13 2015Jun 19 2015We present constraints on testing general relativity (GR) at cosmological scales using recent data sets and assess the impact of galaxy intrinsic alignment (IA) in the CFHTLenS lensing data on those constraints. We consider CMB temperature data from Planck, ... More

The Dixmier-Moeglin equivalence for Leavitt path algebrasMay 24 2010Jun 04 2010Let $K$ be a field, let $E$ be a finite directed graph, and let $L_K(E)$ be the Leavitt path algebra of $E$ over $K$. We show that for a prime ideal $P$ in $L_K(E)$, the following are equivalent: \begin{enumerate} \item $P$ is primitive; \item $P$ is ... More

Effect of a weak ion collisionality on the dynamics of kinetic electrostatic shocksOct 04 2018Feb 06 2019In strictly collisionless electrostatic shocks, the ion distribution function can develop discontinuities along phase-space separatrices, due to partial reflection of the ion population. In this paper, we depart from the strictly collisionless regime ... More

Demonstration of a Cold Atom Fountain Electron Electric Dipole Moment ExperimentFeb 01 2006Mar 14 2006A Cs fountain electron electric dipole moment (EDM) experiment using electric-field quantization is demonstrated. With magnetic fields reduced to 200 pT or less, the electric field lifts the degeneracy between hyperfine levels of different|mF| and, along ... More

Deep Searches for Radio Pulsations and Bursts from Four Southern Anomalous X-ray PulsarsMar 11 2007We have searched for persistent radio pulsations, bright single pulses, and bursts from four Southern anomalous X-ray pulsars (AXPs). Deep observations were conducted at 1.4 GHz in 1999 July and August with the Parkes 64-m telescope. For all of the target ... More

A Generalized Muon Trajectory Estimation Algorithm with Energy Loss for Application to Muon TomographyJan 23 2018This work presents a generalized muon trajectory estimation (GMTE) algorithm to estimate the path of a muon in either uniform or nonuniform media. The use of cosmic ray muons in nuclear nonproliferation and safeguards verification applications has recently ... More

Estimating the Coefficients of a Mixture of Two Linear Regressions by Expectation MaximizationApr 26 2017Oct 16 2018We give convergence guarantees for estimating the coefficients of a symmetric mixture of two linear regressions by expectation maximization (EM). In particular, we show that the empirical EM iterates converge to the target parameter vector at the parametric ... More

Cyber Security Awareness Campaigns: Why do they fail to change behaviour?Jan 09 2019The present paper focuses on Cyber Security Awareness Campaigns, and aims to identify key factors regarding security which may lead them to failing to appropriately change people's behaviour. Past and current efforts to improve information-security practices ... More

NRC-Canada at SMM4H Shared Task: Classifying Tweets Mentioning Adverse Drug Reactions and Medication IntakeMay 11 2018Our team, NRC-Canada, participated in two shared tasks at the AMIA-2017 Workshop on Social Media Mining for Health Applications (SMM4H): Task 1 - classification of tweets mentioning adverse drug reactions, and Task 2 - classification of tweets describing ... More

Properties of a Chemically Enriched Lya Absorption System at z=0.167 and Implications for the Total Baryons in Extended Gaseous Envelopes Around GalaxiesAug 03 2001We present a detailed analysis of the chemical abundances, ionization state, and origin of a partial Lyman limit system (N(HI) ~ 10^{16} cm^{-2}) at low redshift (z=0.167 towards PKS0405-1219). We also present the first estimate of the total baryons in ... More

Spectral Properties of Compressible Magnetohydrodynamic Turbulence from Numerical SimulationsMar 05 2003We analyze the spectral properties of driven, supersonic compressible magnetohydrodynamic (MHD) turbulence obtained via high-resolution numerical experiments, for application to understanding the dynamics of giant molecular clouds. Via angle-averaged ... More

An interleaved sampling scheme for the characterization of single qubit dynamicsMar 22 2010Dec 07 2011In this paper, we demonstrate that interleaved sampling techniques can be used to characterize the Hamiltonian of a qubit and its environmental decoherence rate. The technique offers a significant advantage in terms of the number of measurements that ... More

Unambiguous separation of the inverse spin Hall and anomalous Nernst Effects within a ferromagnetic metal using the spin Seebeck effectJul 24 2014The longitudinal spin Seebeck effect is measured on the ferromagnetic insulator Fe$_3$O$_4$ with the ferromagnetic metal Co$_{0.2}$Fe$_{0.6}$B$_{0.2}$ (CoFeB) as the spin detector. By using a non-magnetic spacer material between the two materials (Ti), ... More

Spectral Energy Distributions of Weak Active Galactic Nuclei Associated With Low-Ionization Nuclear Emission RegionsJan 17 2010We present a compilation of spectral energy distributions of 35 weak AGNs in LINERs using recent data from the published literature. We make use of previously published compilations of data, after complementing and extending them with more recent data. ... More

The graphs with all but two eigenvalues equal to $\pm 1$Oct 24 2013We determine all graphs whose adjacency matrix has at most two eigenvalues (multiplicities included) different from $\pm 1$ and decide which of these graphs are determined by their spectrum. This includes the so-called friendship graphs, which consist ... More

A concurrent precursor inflow method for Large Eddy Simulations and applications to finite length wind farmsMay 05 2014In order to enable simulations of developing wind turbine array boundary layers with highly realistic inflow conditions a concurrent precursor method for Large Eddy Simulations is proposed. In this method we consider two domains simultaneously, i.e. in ... More

Transport fluctuations in integrable models out of equilibriumDec 05 2018We present exact results for the full counting statistics, or the scaled cumulant generating function, pertaining to the transfer of arbitrary conserved quantities across an interface in homogeneous integrable models out of equilibrium. We do this by ... More

Secular and orbital variability of Cir X-1 observed in optical spectraSep 11 2001We have observed variations in the optical emission lines from the X-ray binary Circinus X-1. These variations may be attributed both to orbital variations and to long term secular changes in line strength. We have detected double-peaked H-alpha emission ... More

Initial results from a laboratory emulation of weak gravitational lensing measurementsAug 18 2013Sep 17 2013Weak gravitational lensing observations are a key science driver for the NASA Wide Field Infrared Survey Telescope (WFIRST). To validate the performance of the WFIRST infrared detectors, we have performed a laboratory emulation of weak gravitational lensing ... More

A new cohomological formula for helicity in $\R^{2k+1}$ reveals the effect of a diffeomorphism on helicityMar 08 2009Oct 26 2012The helicity of a vector field is a measure of the average linking of pairs of integral curves of the field. Computed by a six-dimensional integral, it is widely useful in the physics of fluids. For a divergence-free field tangent to the boundary of a ... More

Weak Gravitational Lensing Systematics from Image CombinationOct 12 2013Extremely accurate shape measurements of galaxy images are needed to probe dark energy properties with weak gravitational lensing surveys. To increase survey area with a fixed observing time and pixel count, images from surveys such as the Wide Field ... More

Topological Surface States and Dirac point tuning in ternary Bi2Te2Se class of topological insulatorsJun 04 2012Dec 14 2012Using angle-resolved photoemission spectroscopy, we report electronic structure for representative members of ternary topological insulators. We show that several members of this family, such as Bi2Se2Te, Bi2Te2Se, and GeBi2Te4, exhibit a singly degenerate ... More

Beyond the Knudsen number: assessing thermodynamic non-equilibrium in gas flowsJan 10 2012For more than 150 years the Navier-Stokes equations for thermodynamically quasi-equilibrium flows have been the cornerstone of modern computational fluid dynamics that underpins new fluid technologies. However, the applicable regime of the Navier-Stokes ... More

Gravitational Shear, Flexion and Strong Lensing in Abell 1689Feb 09 2007Jun 07 2007We present a gravitational lensing analysis of the galaxy cluster Abell 1689, incorporating measurements of the weak shear, flexion, and strong lensing induced in background galaxies. This is the first time that a shapelet technique has been used to reconstruct ... More

Prospects for measurement-based quantum computing with solid state spinsJan 20 2009Jan 21 2009This article aims to review the developments, both theoretical and experimental, that have in the past decade laid the ground for a new approach to solid state quantum computing. Measurement-based quantum computing (MBQC) requires neither direct interaction ... More

Semi-Supervised Nonlinear Distance Metric Learning via Forests of Max-Margin Cluster HierarchiesFeb 23 2014Metric learning is a key problem for many data mining and machine learning applications, and has long been dominated by Mahalanobis methods. Recent advances in nonlinear metric learning have demonstrated the potential power of non-Mahalanobis distance ... More

Berkeley Supernova Ia Program II: Initial Analysis of Spectra Obtained Near Maximum BrightnessFeb 09 2012May 04 2012In this second paper in a series we present measurements of spectral features of 432 low-redshift (z < 0.1) optical spectra of 261 Type Ia supernovae (SNe Ia) within 20 d of maximum brightness. The data were obtained from 1989 through the end of 2008 ... More

Leavitt path algebras satisfying a polynomial identityAug 17 2014Leavitt path algebras L of an arbitrary graph E over a field K satisfying a polynomial identity are completely characterized both in graph-theoretic and algebraic terms. When E is a finite graph, L satisfying a polynomial identity is shown to be equivalent ... More