Results for "Yvonne W Lui"

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Identifying Mild Traumatic Brain Injury Patients From MR Images Using Bag of Visual WordsOct 18 2017Feb 14 2018Mild traumatic brain injury (mTBI) is a growing public health problem with an estimated incidence of one million people annually in US. Neurocognitive tests are used to both assess the patient condition and to monitor the patient progress. This work aims ... More
MTBI Identification From Diffusion MR Images Using Bag of Adversarial Visual FeaturesJun 27 2018In this work, we propose bag of adversarial features (BAF) for identifying mild traumatic brain injury (MTBI) patients from their diffusion magnetic resonance images (MRI) (obtained within one month of injury) by incorporating unsupervised feature learning ... More
A Deep Unsupervised Learning Approach Toward MTBI Identification Using Diffusion MRIFeb 08 2018Apr 11 2018Mild traumatic brain injury is a growing public health problem with an estimated incidence of over 1.7 million people annually in US. Diagnosis is based on clinical history and symptoms, and accurate, concrete measures of injury are lacking. This work ... More
Einstein Bianchi equations with sourcesNov 07 2005In this article, dedicated to one of the best specialist of the FOSH systems, we couple the Bianchi equations with the equations satisfied by the dynamical acceleration of a charged fluid and the derivatives of the associated Maxwell field.
Bianchi - Euler system for relativistice fluids and Bel - Robinson type energyJun 29 2002We write a first order symmetric hyperbolic system coupling the Riemann with the dynamical acceleration of a relativistic fluid. W determine the associated, coupled, Bel - Robinson energy, and the integral equality that it satisfies.
On H. Friedrich's formulation of Einstein'equations with fluid sourcesFeb 05 2002We establish a variant, which has the advantage of introducing only physical characteristics, of the symmetric quasi linear first order system given by H.\ Friedrich for the evolution equations of gravitating fluid bodies in General Relativity which can ... More
Constraints and evolution in cosmologyFeb 05 2002We review some old and new results about strict and non strict hyperbolic formulations of the Einstein equations.
Einstein-Bianchi Hyperbolic System for General RelativityOct 07 1997Feb 26 1998By employing the Bianchi identities for the Riemann tensor in conjunction with the Einstein equations, we construct a first order symmetric hyperbolic system for the evolution part of the Cauchy problem of general relativity. In this system, the metric ... More
The Web of Human Sexual ContactsJun 25 2001Many ``real-world'' networks are clearly defined while most ``social'' networks are to some extent subjective. Indeed, the accuracy of empirically-determined social networks is a question of some concern because individuals may have distinct perceptions ... More
An algorithm for computing the canonical bases of higher-level q-deformed Fock spacesSep 14 2006Dec 12 2006We derive a straightening-free algorithm that computes the canonical bases of any higher-level q-deformed Fock space.
Tevatron LegacyFeb 28 2012Several major milestones and discoveries were attained during the lifetime of the Tevatron proton-antiproton collider at Fermilab, from 1987 to 2011. One of the most important was the discovery of the top quark in 1995, followed by an intense program ... More
Canonical bases of higher-level q-deformed Fock spacesJun 09 2006We show that the transition matrices between the standard and the canonical bases of infinitely many weight subspaces of the higher-level q-deformed Fock spaces are equal.
A conjecture for q-decomposition matrices of cyclotomic v-Schur algebrasMay 18 2005Apr 27 2006The Jantzen sum formula for cyclotomic v-Schur algebras yields an identity for some q-analogues of the decomposition matrices of these algebras. We prove a similar identity for matrices of canonical bases of higher-level Fock spaces. We conjecture then ... More
fastMRI: An Open Dataset and Benchmarks for Accelerated MRINov 21 2018Accelerating Magnetic Resonance Imaging (MRI) by taking fewer measurements has the potential to reduce medical costs, minimize stress to patients and make MRI possible in applications where it is currently prohibitively slow or expensive. We introduce ... More
Solar irradiance variability: A six-year comparison between SORCE observations and the SATIRE modelApr 05 2011Aims: We investigate how well modeled solar irradiances agree with measurements from the SORCE satellite, both for total solar irradiance and broken down into spectral regions on timescales of several years. Methods: We use the SATIRE model and compare ... More
Nanotesla-level, shield-less, field-compensation-free, wave-mixing-enhanced body-temperature atomic magnetometry for biomagnetismApr 22 2018We report an optical inelastic-wave-mixing-enhanced atomic magnetometry technique that results in nT-level magnetic field detection at temperatures compatible with the human body without magnetic shielding, zero-field compensation, or high-frequency modulated ... More
Regularity for parabolic integro-differential equations with very irregular kernelsDec 11 2014We prove H\"older regularity for a general class of parabolic integro-differential equations, which (strictly) includes many previous results. We present a proof which avoids the use of a convex envelop as well as give a new covering argument which is ... More
Optical study of the electronic phase transition of strongly correlated YbInCu_4Jul 10 2000Infrared, visible and near-UV reflectivity measurements are used to obtain conductivity as a function of temperature and frequency in YbInCu_4, which exhibits an isostructural phase-transition into a mixed-valent phase below T_v=42 K. In addition to a ... More
Derived invariants for surface algebrasNov 03 2014Mar 25 2016In this paper we study the derived equivalences between surface algebras, introduced by David-Roesler and Schiffler. Each surface algebra arises from a cut of an ideal triangulation of an unpunctured marked Riemann surface with boundary. A cut can be ... More
Analytical treatment of neutrino asymmetry equilibration from flavour oscillations in the early universeMar 19 2002Jun 05 2002A recent numerical study by A. D. Dolgov, S. H. Hansen, S. Pastor, S. T. Petcov, G. G. Raffelt, and D. V. Semikoz (DHPPRS) [hep-ph/0201287] found that complete or partial equilibrium between all active neutrino flavours can be achieved before the big ... More
Flows on Simplicial ComplexesJun 11 2012Given a graph $G$, the number of nowhere-zero $\ZZ_q$-flows $\phi_G(q)$ is known to be a polynomial in $q$. We extend the definition of nowhere-zero $\ZZ_q$-flows to simplicial complexes $\Delta$ of dimension greater than one, and prove the polynomiality ... More
Gluons and gravitons at one loop from ambitwistor stringsNov 27 2017Mar 09 2018We present new and explicit formulae for the one-loop integrands of scattering amplitudes in non-supersymmetric gauge theory and gravity, valid for any number of particles. The results exhibit the colour-kinematics duality in gauge theory and the double-copy ... More
Higher order corrections to the large scale matter power spectrum in the presence of massive neutrinosSep 04 2008Oct 06 2008We present the first systematic derivation of the one-loop correction to the large scale matter power spectrum in a mixed cold+hot dark matter cosmology with subdominant massive neutrino hot dark matter. Starting with the equations of motion for the density ... More
A "Twistor String" Inspired Formula For Tree-Level Scattering Amplitudes in N=8 SUGRAJun 27 2012We propose a new formulation of the complete tree-level S-matrix of N = 8 supergravity. The new formula for n particles in the k R-charge sector is an integral over the Grassmannian G(2,n) and uses the Veronese map into G(k,n). The image of a point in ... More
The odd-even invariant and Hamiltonian circuits in tope graphsOct 17 2016In this paper we consider the question of the existence of Hamiltonian circuits in the tope graphs of central arrangements of hyperplanes. Some of the results describe connections between the existence of Hamiltonian circuits in the arrangement and the ... More
Approximating the Chromatic PolynomialAug 17 2016Chromatic polynomials are important objects in graph theory and statistical physics, but as a result of computational difficulties, their study is limited to graphs that are small, highly structured, or very sparse. We have devised and implemented two ... More
Keller's Theorem RevisitedAug 21 2017Keller's theorem relates the components of the macroscopic dielectric response of a binary two-dimensional composite system with those of the reciprocal system obtained by interchanging its components. We present a derivation of the theorem that, unlike ... More
Probing Strong Field Gravity Through Numerical SimulationsFeb 24 2015This article is an overview of the contributions numerical relativity has made to our understanding of strong field gravity, to be published in the book "General Relativity and Gravitation: A Centennial Perspective", commemorating the 100th anniversary ... More
Thermopower of Graphene Nanoribbons in the Pseudodiffusive RegimeSep 08 2018Thermoelectric measurements for graphene ribbons are currently performed on samples that include atomic disorder via defects and irregular edges. In this work, we investigate the thermopower or Seebeck coefficient of graphene ribbons within the linear ... More
Continued fractions and irrationality exponents for modified Engel and Pierce seriesOct 23 2018An Engel series is a sum of reciprocals of a non-decreasing sequence $(x_n)$ of positive integers, which is such that each term is divisible by the previous one, and a Pierce series is an alternating sum of the reciprocals of a sequence with the same ... More
Grain-resolved kinetics and rotation during grain growth of nanocrystalline Aluminium by molecular dynamicsAug 26 2016Nov 15 2016Grain growth in nanocrystalline Al was studied by means of molecular dynamics simulations. The novelty of this study results from the utilization of an algorithm to resolve per-grain kinetics and orientation change from molecular dynamics data sets. To ... More
Grain reconstruction and determination of grain attributes from MD data sets of FCC polycrystalsAug 26 2016An algorithm for the identification and reconstruction of crystallites from molecular dynamics data sets of FCC materials was developed. The algorithm was tested in an Al polycrystal possessing a weak texture. For the conditions tested, the algorithm ... More
Collision Avoidance for Bi-Steerable Car Using Analytic Left InversionMar 19 2016A case study is presented of a collision avoidance system that directly integrates the kinematics of a bi-steerable car with a suitable path planning algorithm. The first step is to identify a path using the method of rapidly exploring random trees, and ... More
Future Global in time einsteinian spacetimes with U(1) isometry groupDec 19 2001We prove that spacetimes satisfying the vacuum Einstein equations on a manifold of the form $\Sigma \times U(1)\times R$ where $\Sigma $ is a compact surface of genus $G>1$ and where the Cauchy data is invariant with respect to U(1) and sufficiently small ... More
Motion of Isolated bodiesMay 17 2006It is shown that sufficiently smooth initial data for the Einstein-dust or the Einstein-Maxwell-dust equations with non-negative density of compact support develop into solutions representing isolated bodies in the sense that the matter field has spatially ... More
Global Hyperbolicity and CompletenessJan 17 2002Jan 21 2002We prove global hyperbolicity of spacetimes under generic regularity conditions on the metric. We then show that these spacetimes are timelike and null geodesically complete if the gradient of the lapse and the extrinsic curvature $K$ are integrable. ... More
V+jets Background and Systematic Uncertainties in Top Quark AnalysesNov 28 2013Vector boson production in association with jets is an important process to test perturbative quantum chromodynamics and also a background process in top quark analyses. Measurements on vector boson production in association with light and heavy flavour ... More
Discrete-Time Approximations of Fliess OperatorsOct 24 2015A convenient way to represent a nonlinear input-output system in control theory is via a Chen-Fliess functional expansion or Fliess operator. The general goal of this paper is to describe how to approximate Fliess operators with iterated sums and to provide ... More
The Influence of Bars on Nuclear ActivityApr 11 1997We test ideas on fueling of galactic nuclei by bar-driven inflow by comparing the detection rate and intensity of nuclear H II regions and AGNs among barred and unbarred galaxies in a sample of over 300 spirals selected from our recent optical spectroscopic ... More
Second-Harmonic Generation in Nano-Structured MetamaterialsDec 14 2018We conduct a theoretical and numerical study on the second-harmonic (SH) optical response of a nano-structured metamaterial composed of a periodic array of inclusions. Both the inclusions and their surrounding matrix are made of centrosymmetrical materials, ... More
Faa di Bruno Hopf Algebra of the Output Feedback Group for Multivariable Fliess OperatorsJun 20 2014Nov 01 2014Given two nonlinear input-output systems written in terms of Chen-Fliess functional expansions, it is known that the feedback interconnected system is always well defined and in the same class. An explicit formula for the generating series of a single-input, ... More
Diffusion Variational AutoencodersJan 25 2019A standard Variational Autoencoder, with a Euclidean latent space, is structurally incapable of capturing topological properties of certain datasets. To remove topological obstructions, we introduce Diffusion Variational Autoencoders with arbitrary manifolds ... More
Combinatorial Hopf algebra for interconnected nonlinear systemsMay 08 2018A detailed expose of the Hopf algebra approach to interconnected input-output systems in nonlinear control theory is presented. The focus is on input-output systems that can been represented in terms of Chen-Fliess functional expansions or Fliess operators. ... More
Nonextensive Thermostatistics and the $H$-Theorem RevisitedMar 02 2004In this paper we present a new derivation of the $H$-theorem and the corresponding collisional equilibrium velocity distributions, within the framework of Tsallis' nonextensive thermostatistics. Unlike previous works, in our derivation we do not assume ... More
Evolutionary Transitions and Top-Down CausationJul 19 2012Top-down causation has been suggested to occur at all scales of biological organization as a mechanism for explaining the hierarchy of structure and causation in living systems. Here we propose that a transition from bottom-up to top-down causation -- ... More
A combinatorial Hopf algebra for nonlinear output feedback control systemsJun 20 2014Sep 27 2015In this work a combinatorial description is provided of a Faa di Bruno type Hopf algebra which naturally appears in the context of Fliess operators in nonlinear feedback control theory. It is a connected graded commutative and non-cocommutative Hopf algebra ... More
Top Quark Physics at the TevatronFeb 14 2013Mar 26 2013The heaviest known elementary particle, the top quark, was discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton-antiproton collider at Fermilab. Since its discovery, a large program was set in motion by the CDF and D0 collaborations ... More
Cauchy problem with data on a characteristic cone for the Einstein-Vlasov equationsJun 02 2012We show how to solve the Cauchy problem for the Einstein-Vlasov equations with geometric initial data on a light-cone.
When Can a Distributed Ledger Replace a Trusted Third Party?Jun 28 2018The functionality that distributed ledger technology provides, i.e., an immutable and fraud-resistant registry with validation and verification mechanisms, has traditionally been implemented with a trusted third party. Due to the distributed nature of ... More
Relic neutrino clustering and implications for their detectionDec 17 2004We study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter and baryonic structures within the flat $\Lambda$CDM model. We then discuss the implications of clustering for scattering-based relic neutrino detection methods, ... More
Particle Identification with the ALICE Transition Radiation DetectorFeb 14 2014The Transition Radiation Detector (TRD) provides particle identification in the ALICE central barrel. In particular, it allows electron identification via the measurement of transition radiation for $\rm p >$ 1 GeV/$c$, where pions can no longer be rejected ... More
Finite Volume Modeling of Poroelastic-Fluid Wave Propagation with Mapped GridsMay 13 2013In this work we develop a high-resolution mapped-grid finite volume method code to model wave propagation in two dimensions in systems of multiple orthotropic poroelastic media and/or fluids, with curved interfaces between different media. We use a unified ... More
A Search for "Dwarf" Seyfert Nuclei. V. Demographics of Nuclear Activity in Nearby GalaxiesApr 11 1997We use the sample of emission-line nuclei derived from a recently completed optical spectroscopic survey of nearby galaxies to quantify the incidence of local (z = 0) nuclear activity. Consistent with previous studies, we find detectable amounts of ionized ... More
Dendriform-Tree Setting for Fully Non-commutative Fliess OperatorsAug 29 2014This paper provides a dendriform-tree setting for Fliess operators with matrix-valued inputs. This class of analytic nonlinear input-output systems is convenient, for example, in quantum control. In particular, a description of such Fliess operators is ... More
Critical dynamics of gauge systems: Spontaneous vortex formation in 2D superconductorsAug 08 2001Aug 28 2001We examine the formation of vortices during the nonequilibrium relaxation of a high-temperature initial state of an Abelian-Higgs system. We equilibrate the scalar and gauge fields using gauge-invariant Langevin equations and relax the system by instantaneously ... More
On the geometry of moduli spaces of holomorphic chains over compact Riemann surfacesDec 21 2005We study holomorphic $(n+1)$-chains $E_n\to E_{n-1} \to >... \to E_0$ consisting of holomorphic vector bundles over a compact Riemann surface and homomorphisms between them. A notion of stability depending on $n$ real parameters was introduced in the ... More
Misleading Stars: What Cannot Be Measured in the Internet?May 26 2011Jun 19 2011Traceroute measurements are one of our main instruments to shed light onto the structure and properties of today's complex networks such as the Internet. This paper studies the feasibility and infeasibility of inferring the network topology given traceroute ... More
Modeling specific action potentials in the human atria based on a minimal reaction-diffusion modelSep 05 2017We present an effective method to model empirical action potentials of specific patients in the human atria based on the minimal model of Bueno-Orovio, Cherry and Fenton adapted to atrial electrophysiology. In this model, three ionic are currents introduced, ... More
$h$-vectors of small matroid complexesJun 13 2011Stanley conjectured in 1977 that the $h$-vector of a matroid simplicial complex is a pure $O$-sequence. We give simple constructive proofs that the conjecture is true for matroids of rank less than or equal to 3, and corank 2. We used computers to verify ... More
Application of Padé interpolation to stationary state problemsJul 08 2002Feb 05 2003If the small and large coupling behavior of a physical system can be computed perturbatively and expressed respectively as power series in a coupling parameter $g$ and $1/g$, a Pad\'{e} approximant embracing the two series can interpolate between these ... More
The post-AGB evolution of AGB mass loss variationsMay 20 2003We present new numerical hydrodynamical modelling of the evolution of Asymptotic Giant Branch (AGB) mass loss fluctuations during the post-AGB/Planetary Nebula phase. These models show that after ionization, the observable effects of the mass loss fluctuations ... More
Intuitive Source Code Visualization Tools for Improving Student Comprehension: BRICSMar 04 2008Even relatively simple code analysis can be a daunting task for many first year students. Perceived complexity, coupled with foreign and harsh syntax, often outstrips the ability for students to take in what they are seeing in terms of their verbal memory. ... More
Solar Irradiance VariabilityOct 22 2012The Sun has long been considered a constant star, to the extent that its total irradiance was termed the solar constant. It required radiometers in space to detect the small variations in solar irradiance on timescales of the solar rotation and the solar ... More
On the augmented Biot-JKD equations with Pole-Residue representation of the dynamic tortuosityApr 28 2018Sep 18 2018In this paper, we derive the augmented Biot-JKD equations, where the memory terms in the original Biot-JKD equations are dealt with by introducing auxiliary dependent variables. The evolution in time of these new variables are governed by ordinary differential ... More
Measurement and Control of Quasiparticle Dynamics in a Superconducting QubitJun 27 2014Oct 24 2014Superconducting circuits have attracted growing interest in recent years as a promising candidate for fault-tolerant quantum information processing. Extensive efforts have always been taken to completely shield these circuits from external magnetic field ... More
A Schrodinger Cat Living in Two BoxesJan 21 2016Quantum superpositions of distinct coherent states in a single-mode harmonic oscillator, known as "cat states", have been an elegant demonstration of Schrodinger's famous cat paradox. Here, we realize a two-mode cat state of electromagnetic fields in ... More
A Deep Unsupervised Learning Approach Toward MTBI Identification Using Diffusion MRIFeb 08 2018Mild traumatic brain injury (mTBI) is a growing public health problem with an estimated incidence of one million people annually in US. Neurocognitive tests have been used to both assess the patient condition and to monitor the patient progress. This ... More
Einstein constraints on a characteristic coneFeb 07 2010We analyse the Cauchy problem on a characteristic cone, including its vertex, for the Einstein equations in arbitrary dimensions. We use a wave map gauge, solve the obtained constraints and show gauge conservation.
The light-cone theoremMay 13 2009Jun 11 2009We prove that the area of cross-sections of light-cones, in space-times satisfying suitable energy conditions, is smaller than or equal to that of the corresponding cross-sections in Minkowski, or de Sitter, or anti-de Sitter space-time. The equality ... More
Top Quark Mass Measurements at the TevatronSep 23 2013Since the discovery of the top quark in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron proton antiproton collider, precise measurements of its mass are ongoing. Using data recorded by the D0 and CDF experiment, corresponding to up to the ... More
High-Resolution Finite Volume Modeling of Wave Propagation in Orthotropic Poroelastic MediaMay 25 2012Nov 27 2012Poroelasticity theory models the dynamics of porous, fluid-saturated media. It was pioneered by Maurice Biot in the 1930s through 1960s, and has applications in several fields, including geophysics and modeling of in vivo bone. A wide variety of methods ... More
Z-bursts from the Virgo clusterMay 27 2005Sep 02 2005Resonant annihilation of ultra-high energy cosmic neutrinos (UHECnu) on the cosmic neutrino background (CnuB) into Z bosons--the Z-burst mechanism--and its associated absorption and emission phenomenology provide a unique, albeit indirect, probe of the ... More
Neutrinos in Non-linear Structure Formation - The Effect on Halo PropertiesApr 23 2010We use N-body simulations to find the effect of neutrino masses on halo properties, and investigate how the density profiles of both the neutrino and the dark matter components change as a function of the neutrino mass. We compare our neutrino density ... More
On the Windfall and Price of Friendship: Inoculation Strategies on Social NetworksJan 09 2011Jan 11 2011This article investigates selfish behavior in games where players are embedded in a social context. A framework is presented which allows us to measure the Windfall of Friendship, i.e., how much players benefit (compared to purely selfish environments) ... More
Global solutions of the Einstein-Maxwell equations in higher dimensionsAug 24 2006Nov 01 2006We consider the Einstein-Maxwell equations in space-dimension $n$. We point out that the Lindblad-Rodnianski stability proof applies to those equations whatever the space-dimension $n\ge 3$. In even space-time dimension $n+1\ge 6$ we use the standard ... More
An existence theorem for the Cauchy problem on a characteristic cone for the Einstein equationsJun 29 2010We prove an existence theorem for the Cauchy problem on a characteristic cone for the vacuum Einstein equations.
Solar irradiance models and measurements: a comparison in the 220 nm to 240 nm wavelength bandNov 08 2011Solar irradiance models that assume solar irradiance variations to be due to changes in the solar surface magnetic flux have been successfully used to reconstruct total solar irradiance on rotational as well as cyclical and secular time scales. Modelling ... More
Loop Integrands for Scattering Amplitudes from the Riemann SphereJul 01 2015Sep 10 2015The scattering equations on the Riemann sphere give rise to remarkable formulae for tree-level gauge theory and gravity amplitudes. Adamo, Casali and Skinner conjectured a one-loop formula for supergravity amplitudes based on scattering equations on a ... More
Algebraic and combinatorial aspects of sandpile monoids on directed graphsMay 12 2011Aug 17 2012The sandpile group of a graph is a well-studied object that combines ideas from algebraic graph theory, group theory, dynamical systems, and statistical physics. A graph's sandpile group is part of a larger algebraic structure on the graph, known as its ... More
Adaptability of non-genetic diversity in bacterial chemotaxisNov 25 2015Bacterial chemotaxis systems are as diverse as the environments that bacteria inhabit, but how much environmental variation can cells tolerate with a single system? Diversification of a single chemotaxis system could serve as an alternative, or even evolutionary ... More
Kinetics of Particles in Relativistic Collisionless ShocksOct 14 2003Charged plasma particles form an anisotropic counter-streaming distribution at the front of a shock. In the near- and ultra-relativistic regimes, Weibel (or two-stream) instability produces near-equipartition, chaotic, small-scale magnetic fields. The ... More
Macroscopic optical response and photonic bandsDec 21 2012We develop a formalism for the calculation of the macroscopic dielectric response of composite systems made of particles of one material embedded periodically within a matrix of another material, each of which is characterized by a well defined dielectric ... More
Single Top Quark Production at the TevatronOct 26 2012While the heaviest known elementary particle, the top quark, has been discovered in 1995 by the CDF and D0 collaborations in ttbar events, it took 14 more years until the observation of single top quark production. In this article, we discuss recent studies ... More
A non local Monge-Ampere equationOct 01 2014Jun 26 2015We introduce a non local analog to the Monge-Ampere operator and show some of its properties. We prove that a global problem involving this operator has C 1,1 solutions in the full space.
On the Evans-Krylov theoremMay 08 2009Sep 08 2010In this note, motivated by our work on integral fully nonlinear equations, we provide a variation of the proof of Evans-Krylov theorem about the interior $C^{2,\alpha}$ a priori estimate for concave fully nonlinear elliptic equations. The proof we present ... More
The Central Regions of Early-Type Galaxies Hosting Active Galactic Nuclei as Viewed with HST/NICMOSFeb 28 2001We present preliminary results from surface photometry of a sample of early-type galaxies observed with NICMOS on board HST in the F160W (H-band) filter. Dust is found to occur mostly in galaxies which possess unresolved nuclei, and in a few cases the ... More
Discovery of Radio Outbursts in the Active Nucleus of M81May 06 1999The low-luminosity active galactic nucleus of M81 has been monitored at centimeter wavelengths since early 1993 as a by-product of radio programs to study the radio emission from Supernova 1993J. The extensive data sets reveal that the nucleus experienced ... More
A Search for "Dwarf" Seyfert Nuclei. IV. Nuclei with Broad H-alpha EmissionApr 11 1997We present the results of an optical spectroscopic survey designed to search for low-luminosity, "dwarf" Seyfert nuclei in a magnitude-limited sample of 486 bright, northern galaxies. Moderate-resolution spectra of exceptionally high quality were obtained ... More
Stellar Winds and Embedded Star Formation in the Galactic Center Quintuplet and Arches Clusters: Multifrequency Radio ObservationsAug 08 2005A multi-frequency, multi-configuration study has been made of the compact radio sources in the Galactic Center Quintuplet and Arches stellar clusters using the Very Large Array. Ten radio sources have been detected in the Quintuplet cluster. The majority ... More
Non-line-of-sight Node Localization based on Semi-Definite Programming in Wireless Sensor NetworksDec 31 2009An unknown-position sensor can be localized if there are three or more anchors making time-of-arrival (TOA) measurements of a signal from it. However, the location errors can be very large due to the fact that some of the measurements are from non-line-of-sight ... More
An Architecture for Person-Following using Active Target SearchSep 24 2018This paper addresses a novel architecture for person-following robots using active search. The proposed system can be applied in real-time to general mobile robots for learning features of a human, detecting and tracking, and finally navigating towards ... More
The Evans-Krylov theorem for non local fully non linear equationsMay 08 2009We prove an interior regularity result for solutions of a purely integro-differential Bellman equation. This regularity is enough for the solutions to be understood in the classical sense. If we let the order of the equation approach two, we recover the ... More
Effective Dielectric Response of MetamaterialsJan 22 2009Jun 18 2009We use a homogenization procedure for Maxwell's equations in order to obtain in the local limit the frequency ($\omega$) dependent macroscopic dielectric response $\epsilon^M(\omega)$ of metamaterials made of natural constituents with any geometrical ... More
Optical and Electrical Properties of Nanostructured Metallic Electrical ContactsSep 15 2016We study the optical and electrical properties of silver films with a graded thickness obtained through metallic evaporation in vacuum on a tilted substrate to evaluate their use as semitransparent electrical contacts. We measure their ellipsometric coefficients, ... More
The Many Faces of Graph DynamicsAug 05 2016The topological structure of complex networks has fascinated researchers for several decades, resulting in the discovery of many universal properties and reoccurring characteristics of different kinds of networks. However, much less is known today about ... More
Top quark Physics at the TevatronJan 06 2012When the heaviest elementary particle known today, the top quark, was discovered in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron collider, a large program to study this particle in details has started. In this article, an overview of ... More
The Many Faces of Graph DynamicsAug 05 2016Oct 12 2016The topological structure of complex networks has fascinated researchers for several decades, resulting in the discovery of many universal properties and reoccurring characteristics of different kinds of networks. However, much less is known today about ... More
Effect of uncertainties in stellar model parameters on estimated masses and radii of single starsNov 29 2011Accurate and precise values of radii and masses of stars are needed to correctly estimate properties of extrasolar planets. We examine the effect of uncertainties in stellar model parameters on estimates of the masses, radii and average densities of solar-type ... More
Is it possible to tell the difference between fermionic and bosonic hot dark matter?Jul 22 2005We study the difference between thermally produced fermionic and bosonic hot dark matter in detail. In the linear regime of structure formation, their distinct free-streaming behaviours can lead to pronounced differences in the matter power spectrum. ... More
One-loop amplitudes on the Riemann sphereNov 19 2015Mar 16 2016The scattering equations provide a powerful framework for the study of scattering amplitudes in a variety of theories. Their derivation from ambitwistor string theory led to proposals for formulae at one loop on a torus for 10 dimensional supergravity, ... More