Results for "Eric T. Chung"

total 78297took 0.45s
Adaptive generalized multiscale finite element methods for H(curl)-elliptic problems with heterogeneous coefficientsFeb 08 2018In this paper, we construct an adaptive multiscale method for solving H(curl)-elliptic problems in highly heterogeneous media. Our method is based on the generalized multiscale finite element method. We will first construct a suitable snapshot space, ... More
Generalized Multiscale Finite Element Method for Elasticity EquationsAug 25 2014In this paper, we discuss the application of Generalized Multiscale Finite Element Method (GMsFEM) to elasticity equation in heterogeneous media. Our applications are motivated by elastic wave propagation in subsurface where the subsurface properties ... More
Mixed GMsFEM for the simulation of waves in highly heterogeneous mediaSep 08 2015Numerical simulations of waves in highly heterogeneous media have important applications, but direct computations are prohibitively expensive. In this paper, we develop a new generalized multiscale finite element method with the aim of simulating waves ... More
An adaptive GMsFEM for high-contrast flow problemsSep 24 2013In this paper, we derive an a-posteriori error indicator for the Generalized Multiscale Finite Element Method (GMsFEM) framework. This error indicator is further used to develop an adaptive enrichment algorithm for the linear elliptic equation with multiscale ... More
An enriched multiscale mortar space for high contrast flow problemsSep 08 2016Mortar methods are widely used techniques for discretizations of partial differential equations and preconditioners for the algebraic systems resulting from the discretizations. For problems with high contrast and multiple scales, the standard mortar ... More
A conservative local multiscale model reduction technique for Stokes flows in heterogeneous perforated domainsAug 25 2016In this paper, we present a new multiscale model reduction technique for the Stokes flows in heterogeneous perforated domains. The challenge in the numerical simulations of this problem lies in the fact that the solution contains many multiscale features ... More
Generalized multiscale finite element methods for wave propagation in heterogeneous mediaJun 29 2013Numerical modeling of wave propagation in heterogeneous media is important in many applications. Due to the complex nature, direct numerical simulations on the fine grid are prohibitively expensive. It is therefore important to develop efficient and accurate ... More
Generalized multiscale finite element methods for space-time heterogeneous parabolic equationsMay 24 2016In this paper, we consider local multiscale model reduction for problems with multiple scales in space and time. We developed our approaches within the framework of the Generalized Multiscale Finite Element Method (GMsFEM) using space-time coarse cells. ... More
Goal-oriented adaptivity for GMsFEMSep 18 2015In this paper we develop two goal-oriented adaptive strategies for a posteriori error estimation within the generalized multiscale finite element framework. In this methodology, one seeks to determine the number of multiscale basis functions adaptively ... More
Residual-driven online Generalized Multiscale Finite Element MethodsJan 19 2015The construction of local reduced-order models via multiscale basis functions has been an area of active research. In this paper, we propose online multiscale basis functions which are constructed using the offline space and the current residual. Online ... More
Re-iterated multiscale model reduction using the GMsFEMJun 18 2016Numerical homogenization and multiscale finite element methods construct effective properties on a coarse grid by solving local problems and extracting the average effective properties from these local solutions. In some cases, the solutions of local ... More
An online generalized multiscale discontinuous Galerkin method (GMsDGM) for flows in heterogeneous mediaApr 17 2015Offline computation is an essential component in most multiscale model reduction techniques. However, there are multiscale problems in which offline procedure is insufficient to give accurate representations of solutions, due to the fact that offline ... More
Mixed Generalized Multiscale Finite Element Methods and ApplicationsJun 04 2014In this paper, we present a mixed Generalized Multiscale Finite Element Method (GMsFEM) for solving flow in heterogeneous media. Our approach constructs multiscale basis functions following a GMsFEM framework and couples these basis functions using a ... More
Adaptive mixed GMsFEM for flows in heterogeneous mediaJul 07 2015In this paper, we present two adaptive methods for the basis enrichment of the mixed Generalized Multiscale Finite Element Method (GMsFEM) for solving the flow problem in heterogeneous media. We develop an a-posteriori error indicator which depends on ... More
Generalized Multiscale Finite Element Methods for problems in perforated heterogeneous domainsJan 14 2015Complex processes in perforated domains occur in many real-world applications. These problems are typically characterized by physical processes in domains with multiple scales (see Figure 1 for the illustration of a perforated domain). Moreover, these ... More
An adaptive generalized multiscale discontinuous Galerkin method (GMsDGM) for high-contrast flow problemsSep 11 2014In this paper, we develop an adaptive Generalized Multiscale Discontinuous Galerkin Method (GMs-DGM) for a class of high-contrast flow problems, and derive a-priori and a-posteriori error estimates for the method. Based on the a-posteriori error estimator, ... More
A staggered discontinuous Galerkin method for a class of nonlinear elliptic equationsOct 07 2016In this paper, we present a staggered discontinuous Galerkin (SDG) method for a class of nonlinear elliptic equations in two dimensions. The SDG methods have some distinctive advantages, and have been successfully applied to a wide range of problems including ... More
Multiscale stabilization for convection-dominated diffusion in heterogeneous mediaSep 23 2015We develop a Petrov-Galerkin stabilization method for multiscale convection-diffusion transport systems. Existing stabilization techniques add a limited number of degrees of freedom in the form of bubble functions or a modified diffusion, which may not ... More
Online Adaptive Local Multiscale Model Reduction for Heterogeneous Problems in Perforated DomainsMay 24 2016In this paper, we develop and analyze an adaptive multiscale approach for heterogeneous problems in perforated domains. In many applications, these problems have a multiscale nature arising because of the perforations, their geometries, the sizes of the ... More
Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic mediaSep 11 2014Apr 18 2015It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference ... More
BDDC and FETI-DP algorithms with adaptive coarse spaces for three-dimensional elliptic problems with oscillatory and high contrast coefficientsJun 24 2016BDDC and FETI-DP algorithms are developed for three-dimensional elliptic problems with adaptively enriched coarse components. It is known that these enriched components are necessary in the development of robust preconditioners. To form the adaptive coarse ... More
Adaptive multiscale model reduction with Generalized Multiscale Finite Element MethodsApr 28 2016In this paper, we discuss a general multiscale model reduction framework based on multiscale finite element methods. We give a brief overview of related multiscale methods. Due to page limitations, the overview focuses on a few related methods and is ... More
Stabilization of ultra-short pulses in cubic nonlinear mediaDec 13 2005Apr 07 2006We study the propagation of ultra-short pulses in a cubic nonlinear medium. Using multiple-scale technique, we derive a new wave equation that preserves the nonlocal dispersion present in Maxwell's equations. As a result, we are able to understand how ... More
Nonlinear Color-Metallicity Relations of Globular Clusters. III. On the Discrepancy in Metallicity between Globular Cluster Systems and their Parent Elliptical GalaxiesSep 23 2011One of the conundrums in extragalactic astronomy is the discrepancy in observed metallicity distribution functions (MDFs) between the two prime stellar components of early-type galaxies-globular clusters (GCs) and halo field stars. This is generally taken ... More
Alternative subtraction scheme using Nagy Soper dipolesJan 15 2010We present an alternative subtraction scheme for the treatment of infrared divergences in NLO QCD calculations. In this scheme, the number of transformations is greatly reduced with respect to the standard subtraction scheme by Catani and Seymour. We ... More
Sparse Generalized Multiscale Finite Element Methods and their applicationsJun 29 2015Aug 03 2015In a number of previous papers, local (coarse grid) multiscale model reduction techniques are developed using a Generalized Multiscale Finite Element Method. In these approaches, multiscale basis functions are constructed using local snapshot spaces, ... More
Staggered Discontinuous Galerkin approximation for Immersed Boundary MethodSep 05 2016In this paper, we present a staggered discontinuous Galerkin immersed boundary method (SDG-IBM) for the numerical approximation of fluid-structure interaction. The immersed boundary method is used to model the fluid-structure interaction, while the fluid ... More
Method and Advantages of Genetic Algorithms in Parameterization of Interatomic Potentials: Metal-OxidesJun 05 2013The method and the advantages of an evolutionary computing based approach using a steady state genetic algorithm (GA) for the parameterization of interatomic potentials for metal oxides within the shell model framework are developed and described. We ... More
Anomalous thermoelectric transport in two-dimensional Bose gasJun 17 2013In condensed matter physics, transport measurements are essential not only for the characterization of materials, but also to discern between quantum phases and identify new ones. The extension of these measurements into atomic quantum gases is emerging ... More
An Equivariant Liapunov Stability Test and the Energy-Momentum-Casimir MethodJul 12 2001Feb 11 2002We present an equivariant Liapunov stability criterion for dynamical systems with symmetry. This result yields a simple proof of the energy-momentum-Casimir stability analysis of relative equilibria of equivariant Hamiltonian systems.
On the tenth-order mock theta functionsSep 16 2016Oct 09 2016Using properties of Appell-Lerch functions, we give insightful proofs for six of Ramanujan's identities for the tenth-order mock theta functions.
A double-sum Kronecker-type identityJan 08 2016Aug 11 2016We prove a double-sum analog of an identity known to Kronecker and then express it in terms of functions studied by Appell and Kronecker's student Lerch, in so doing we show that the double-sum analog is of mixed mock modular form. We also give related ... More
Long distance coherent tunneling effect on the charge and heat currents in serially coupled triple quantum dotsSep 06 2013Mar 12 2014The effect of long distance coherent tunneling (LDCT) on the charge and heat currents in serially coupled triple quantum dots (TQDs) connected to electrodes is illustrated by using a combination of the extended Hurbbard model and Anderson model. The charge ... More
Bipolar thermoelectric effect in a srially coupled quantum dot systemApr 14 2011Nov 01 2011The Seebeck coefficient (S) of a serially coupled quantum dot (SCQD) junction system is theoretically studied via a two-level Anderson model. A change of sign in S with respect to temperature is found, which arises from the competition between tunneling ... More
Thermoelectric and thermal rectification properties of quantum dot junctionsFeb 21 2010The electrical conductance, thermal conductance, thermal power and figure of merit (ZT) of semiconductor quantum dots (QDs) embedded into an insulator matrix connected with metallic electrodes are theoretically investigated in the Coulomb blockade regime. ... More
Tunnelling current and emission spectrum of a single electron transistor under optical pumpingJun 01 2005Theoretical studies of the tunnelling current and emission spectrum of a single electron transistor (SET) under optical pumping are presented. The calculation is performed via Keldysh Green's function method within the Anderson model with two energy levels. ... More
Effects of electron correlation on the photocurrent in quantum dot infrared photodetectorsOct 16 2002The effect of electron correlation on the photocurrent of self-assembled InAs/InGaAs quantum dot infrared photo-detector (QDIPs) is studied. It is found that Coulomb interaction and level mixing in the many-body open system lead to double peaks associated ... More
Stokes tomography of radio pulsar magnetospheres. I. Linear polarizationOct 14 2010Dec 20 2010Polarimetric studies of pulsar radio emission traditionally concentrate on how the Stokes vector (I, Q, U, V) varies with pulse longitude, with special emphasis on the position angle (PA) swing of the linearly polarized component. The interpretation of ... More
Thermoelectric Properties of a Semiconductor Quantum Dot Chain Connected to Metallic ElectrodesSep 04 2012Jan 10 2013The thermoelectric properties of a semiconduct quantum dot chain (SQDC) connected to metallic electrodes are theoretically investigated in the Coulomb blockade regime. An extended Hubbard model is employed to simulate the SQDC system consisted of {\color{blue}N=2,3,4, ... More
Bistable states of quantum dot array junctions for high-density memoryDec 29 2008We demonstrate that two-dimensional (2D) arrays of coupled quantum dots (QDs) with six-fold degenerate p orbitals can display bistable states, suitable for application in high-density memory device with low power consumption. Due to the inter-dot coupling ... More
Thermal rectification properties of multiple-quantum-dot junctionsJan 08 2010It is illustrated that semiconductor quantum dots (QDs) embedded into an insulating matrix connected with metallic electrodes and some vacuum space can lead to significant thermal rectification effect. A multilevel Anderson model is used to investigate ... More
Light emitting single electron transistorsJun 03 2006Jun 22 2006The dynamic properties of light-emitting single-electron transistors (LESETs) made from quantum dots are theoretically studied by using nonequilibrium Green's function method. Holes residing at QD created by small ac signals added in the base electrode ... More
Stark effect on the exciton complexes of individual quantum dotsOct 17 2005The emission spectrum of exciton complexes formed in individual self-assembled quantum dots (QDs) embedded into a p-n junction is theoretically studied using an effective mass model. We calculate the particle Coulomb interactions, eletron-hole overlaps ... More
Tunneling current spectroscopy of a nanostructure junction involving multiple energy levelsFeb 05 2007A multi-level Anderson model is employed to simulate the system of a nanostructure tunnel junction with any number of one-particle energy levels. The tunneling current, including both shell-tunneling and shell-filling cases, is theoretically investigated ... More
Stokes tomography of radio pulsar magnetospheres. II. Millisecond pulsarsApr 06 2011The radio polarization characteristics of millisecond pulsars (MSPs) differ significantly from those of non-recycled pulsars. In particular, the position angle (PA) swings of many MSPs deviate from the S-shape predicted by the rotating vector model, even ... More
Untangling the Web of E-Research: Towards a Sociology of Online KnowledgeAug 14 2009e-Research is a rapidly growing research area, both in terms of publications and in terms of funding. In this article we argue that it is necessary to reconceptualize the ways in which we seek to measure and understand e-Research by developing a sociology ... More
Indirect Inference With(Out) ConstraintsJul 21 2016Aug 30 2016The traditional implementation of Indirect Inference (I-I) is to perform inference on structural parameters $\theta$ by matching observed and simulated auxiliary statistics. These auxiliary statistics are consistent estimators of instrumental parameters ... More
A Simple Holographic InsulatorJun 16 2014Jul 11 2014We present a simple holographic model of an insulator. Unlike most previous holographic insulators, the zero temperature infrared geometry is completely nonsingular. Both the low temperature DC conductivity and the optical conductivity at zero temperature ... More
DiscoverFriends: Secure Social Network Communication in Mobile Ad Hoc NetworksMay 27 2015May 02 2016This paper presents a secure communication application called DiscoverFriends. Its purpose is to securely communicate to a group of online friends while bypassing their respective social networking servers under a mobile ad hoc network environment. DiscoverFriends ... More
Quantum phase transitions in a resonant-level model with dissipation: Renormalization-group studiesJun 14 2007We study a spinless level that hybridizes with a fermionic band and is also coupled via its charge to a dissipative bosonic bath. We consider the general case of a power-law hybridization function $\Gamma(\w)\propto |\w|^r$ with $r\ge 0$, and a bosonic ... More
Higgs-Stoponium Mixing Near the Stop-Antistop ThresholdSep 15 2016Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop ... More
Micromagnetic Simulation of Amorphous Ferrimagnetic TbFeCo Films with Exchange Coupled NanophasesApr 30 2016Amorphous ferrimagnetic TbFeCo thin films are found to exhibit exchange bias effect near the compensation temperature by magnetic hysteresis loop measurement. The observed exchange anisotropy is believed to originate from the exchange interaction between ... More
Bistability in the Tunnelling Current through a Ring of $N$ Coupled Quantum DotsMay 26 2012We study bistability in the electron transport through a ring of N coupled quantum dots with two orbitals in each dot. One orbital is localized (called b orbital) and coupling of the b orbitals in any two dots is negligible; the other is delocalized in ... More
Quantum interference and structure-dependent orbital-filling effects on the thermoelectric properties of quantum dot moleculesMay 15 2015Jun 30 2015The quantum interference and orbital filling effects on the thermoelectric (TE) properties of quantum dot molecules with high figure of merit are illustrated via the full solution to the Hubbard- Anderson model in the Coulomb blockade regime. It is found ... More
Endpoint Logarithms in e+e- -> J/psi + eta_cJan 16 2013We investigate the origin of the double logarithms of Q^2/m_c^2 that appear in the calculation of the cross section for e+e- -> J/psi + eta_c at next-to-leading order in alpha_s. We find that, diagram-by-diagram, the double logarithms are accounted for ... More
A Consistent Picture for Resonance Neutron Peak and ARPES Spectra in High-Tc SuperconductorsDec 30 1999The spectra observed in ARPES measurements are examined together with the resonance peak observed in neutron scatterings, based on the slave-boson approach to $t-t^{\prime}-J$ model. We show that the peak/dip/hump features arise from the scattering of ... More
Low-energy Spectra of the t-J-Type Models Studied by Variational ApproachSep 28 2006We discuss recent progress of understanding the phenomena observed in high Tc cuprates by studying the d-wave resonating-valence-bond (d-RVB) based trial wave functions for the 2-dimensional t-J-type models. Treat exactly the strong correlation between ... More
Inflationary Cosmology Connecting Dark Energy and Dark MatterApr 24 2007Oct 09 2007Kination dominated quintessence models of dark energy have the intriguing feature that the relic abundance of thermal cold dark matter can be significantly enhanced compared to the predictions from standard cosmology. Previous treatments of such models ... More
Theory of spin blockade, charge ratchet effect, and thermoelectrical behavior in serially coupled quantum-dot systemJan 30 2011Oct 30 2011The charge transport of a serially coupled quantum dots (SCQD) connected to the metallic electrodes is theoretically investigated in the Coulomb blockade regime. A closed-form expression for the tunneling current of SCQD in the {\color{red} weak interdot ... More
Order-alpha_s corrections to the quarkonium electromagnetic current at all orders in the heavy-quark velocityJul 16 2008Jan 14 2009We compute in order alpha_s the nonrelativistic QCD (NRQCD) short-distance coefficients that match quark-antiquark operators of all orders in the heavy-quark velocity v to the electromagnetic current. We employ a new method to compute the one-loop NRQCD ... More
IPA-CuCl$_3$: a S=1/2 Ladder with Ferromagnetic RungsJun 15 2005The spin gap material IPA-CuCl3 has been extensively studied as a ferromagnetic-antiferromagnetic bondalternating S = 1/2 chain. This description of the system was derived from structural considerations and bulk measurements. New inelastic neutron scattering ... More
Double Logarithms in $e^+ e^- \to J/ψ+ η_c$Jun 07 2014Nov 07 2014Double logarithms of $Q^2/m_c^2$ that appear in the cross section for $e^+e^-\to J/\psi + \eta_c$ at next-to-leading order (NLO) in the strong coupling $\alpha_s$ account for the bulk of the NLO correction at $B$-factory energies. (Here, $Q^2$ is the ... More
Duplication Models for Biological NetworksAug 31 2002Are biological networks different from other large complex networks? Both large biological and non-biological networks exhibit power-law graphs (number of nodes with degree k, N(k) ~ k-b) yet the exponents, b, fall into different ranges. This may be because ... More
Designing a cross-correlation search for continuous-wave gravitational radiation from a neutron star in the supernova remnant SNR 1987AFeb 23 2011A strategy is devised for a semi-coherent cross-correlation search for a young neutron star in the supernova remnant SNR 1987A, using science data from the Initial LIGO and/or Virgo detectors. An astrophysical model for the gravitational wave phase is ... More
Does the accreting millisecond pulsar XTE J1814-338 precess?Aug 28 2008Oct 23 2008Precession in an accretion-powered pulsar is expected to produce characteristic variations in the pulse properties. Assuming surface intensity maps with one and two hotspots, we compute theoretically the periodic modulation of the mean flux, pulse-phase ... More
A heat engine made of quantum dot molecules with high figure of meritsJan 05 2016The transport of electrons through serially coupled quantum dot molecules (SCQDM) is investigated theoretically for application as an energy harvesting engine (EHE), which converts thermal heat to electrical power. We demonstrate that the charge current ... More
Quantum interference and electron correlation in charge transport through triangular quantum dot moleculesJan 30 2015We study the charge transport properties of triangular quantum dot molecule (TQDM) connected to metallic electrodes, taking into account all correlation functions and relevant charging states. The quantum interference (QI) effect of TQDM resulting from ... More
Precise Orbital Parameters and Anomalous Phase Variations of the Accretion-powered Millisecond Pulsar XTE J1807-294Jan 07 2008This study reports pulse variation analysis results for the forth discovered accretion-powered millisecond pulsar XTE J1807-294 during its 2003 outburst observed by {\it Rossi X-ray Timing Explorer}. The pulsation is significantly detected only in the ... More
Higgs-Stoponium Mixing Near the Stop-Antistop ThresholdSep 15 2016Oct 03 2016Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop ... More
Spectral Weights, d-wave Pairing Amplitudes, and Particle-hole Tunneling Asymmetry of a Strongly Correlated SuperconductorJun 25 2006Sep 23 2006The spectral weights (SW's) for adding and removing an electron of the Gutzwiller projected d-wave superconducting (SC) state of the t-J-type models are studied numerically on finite lattices. Restrict to the uniform system but treat exactly the strong ... More
Mean lattice point discrepancy bounds, II: Convex domains in the planeJan 08 2005Feb 08 2007We consider planar curved strictly convex domains with no or very weak smoothness assumptions and prove sharp bounds for square-functions associated to the lattice point discrepancy.
Comparison of the color-evaporation model and the NRQCD factorization approach in charmonium productionApr 03 2005Jul 06 2005We compare the color-evaporation model (CEM) and nonrelativistic QCD (NRQCD) factorization predictions for inclusive quarkonium production. Using the NRQCD factorization formulas for quarkonium production and for perturbative QQ-bar production, we deduce ... More
Multi-Level Analysis and Annotation of Arabic Corpora for Text-to-Sign Language MTMay 24 2016In this paper, we present an ongoing effort in lexical semantic analysis and annotation of Modern Standard Arabic (MSA) text, a semi automatic annotation tool concerned with the morphologic, syntactic, and semantic levels of description.
Quadratic algebras of skew type and the underlying semigroupsOct 15 2002We consider algebras over a field K defined by a presentation K <x_1,..., x_n : R >, where $R$ consists of n choose 2 square-free relations of the form x_i x_j = x_k x_l with every monomial x_i x_j, i different from j, appearing in one of the relations. ... More
The Corona Problem for Kernel Multiplier AlgebrasOct 31 2014Oct 10 2016We prove an alternate Toeplitz corona theorem for the algebras of pointwise kernel multipliers of Besov-Sobolev spaces on the unit ball in $\mathbb{C}^{n}$, and for the algebra of bounded analytic functions on certain strictly pseudoconvex domains and ... More
QCD Corrections to W Boson plus Heavy Quark Production at the TevatronNov 29 1995The next-to-leading order QCD corrections to the production of a $W$-boson in association with a jet containing a heavy quark are presented. The calculation is fully differential in the final state particle momenta and includes the mass of the heavy quark. ... More
Massive quiver matrix models for massive charged particles in AdSOct 15 2015We present a new class of ${\cal N}=4$ supersymmetric quiver matrix models and argue that it describes the stringy low-energy dynamics of internally wrapped D-branes in four-dimensional anti-de Sitter (AdS) flux compactifications. The Lagrangians of these ... More
The Mass Dependence of Dwarf Satellite Galaxy QuenchingJul 22 2014We combine observations of the Local Group with data from the NASA-Sloan Atlas to show the variation in the quenched fraction of satellite galaxies from low mass dwarf spheroidals and dwarf irregulars to more massive dwarfs similar to the Magellanic clouds. ... More
Planetary Nebulae Principles & Paradigms: Binaries, Accretion, Magnetic FieldsAug 30 2007Oct 01 2007Observations suggest that many, if not all, post AGB systems evolve through an aspherical outflow phase. Such outflows require a sufficient engine rotational energy which binaries can provide. Via common envelope evolution, binaries can directly eject ... More
Diffusive Migration of Low-Mass Proto-planets in Turbulent DisksMar 09 2006Apr 28 2006Torque fluctuations due to magnetorotational turbulence in proto-planetary disks may greatly influence the migration patterns and survival probabilities of nascent planets. Provided that the turbulence is a stationary stochastic process with finite amplitude ... More
Exclusive Double-Charmonium Production from e^+ e^- Annihilation into Two Virtual PhotonsDec 24 2002Oct 25 2005We calculate the contributions from QED processes involving two virtual photons to the cross sections for e^+ e^- annihilation into two charmonium states with the same C-parity. Generically, the cross sections are three orders of magnitude smaller than ... More
e^+ e^- Annihilation into J/psi + J/psiDec 13 2002Oct 25 2005Recent measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. We suggest that a significant part of the discrepancy can be explained by the process ... More
Machine Learning of User Profiles: Representational IssuesDec 09 1997Dec 11 1997As more information becomes available electronically, tools for finding information of interest to users becomes increasingly important. The goal of the research described here is to build a system for generating comprehensible user profiles that accurately ... More
Confronting Models of Dwarf Galaxy Quenching with Observations of the Local GroupJun 07 2013A number of mechanisms have been proposed to connect star-forming dwarf irregular galaxies with the formation of non-star-forming dwarf spheroidal galaxies, but distinguishing between these mechanisms has been difficult. We use the Via Lactea dark matter ... More
W plus Heavy Quark Production at the TevatronJun 03 1996We present the next-to-leading order QCD corrections to the production of a $W$-boson in association with a jet containing a heavy quark. The calculation is fully differential in the final state particle momenta and includes the mass of the heavy quark. ... More
Magnetic Fields and Massive Star FormationJul 15 2014Massive stars ($M > 8$ \msun) typically form in parsec-scale molecular clumps that collapse and fragment, leading to the birth of a cluster of stellar objects. We investigate the role of magnetic fields in this process through dust polarization at 870 ... More
The Open Connectome Project Data Cluster: Scalable Analysis and Vision for High-Throughput NeuroscienceJun 15 2013Jun 18 2013We describe a scalable database cluster for the spatial analysis and annotation of high-throughput brain imaging data, initially for 3-d electron microscopy image stacks, but for time-series and multi-channel data as well. The system was designed primarily ... More
An Efficient Approach for Computing Optimal Low-Rank Regularized Inverse MatricesApr 06 2014Standard regularization methods that are used to compute solutions to ill-posed inverse problems require knowledge of the forward model. In many real-life applications, the forward model is not known, but training data is readily available. In this paper, ... More
Modeling Porous Dust Grains with Ballistic Aggregates. II. Light Scattering PropertiesJan 15 2009We study the light scattering properties of random ballistic aggregates constructed in Shen et al. (Paper I). Using the discrete-dipole-approximation, we compute the scattering phase function and linear polarization for random aggregates with various ... More
Astala's Conjecture on Distortion of Hausdorff Measures under Quasiconformal Maps in the PlaneMay 30 2008Jul 24 2009Let E be a compact set in the plane, g be a K-quasiconformal map, and let 0<t<2. Then H^t (E) = 0 implies H^{t'} (g E) = 0, for t'=[2Kt]/[2+(K-1)t]. This is a refinement of a set of inequalities on the distortion of Hausdorff dimensions by quasiconformal ... More
Modeling Porous Dust Grains with Ballistic Aggregates I: Geometry and Optical PropertiesJan 14 2008Aug 21 2008We investigate the scattering and absorption of light by random ballistic aggregates of spherical monomers. We present a general measure for the porosity of an irregular particle. Three different classes of ballistic aggregates are considered, with different ... More
On-chip Inter-modal Brillouin ScatteringNov 11 2016Stimulated Brillouin interactions mediate nonlinear coupling between photons and acoustic phonons through an optomechanical three-wave interaction. Though these nonlinearities were previously very weak in silicon photonic systems, the recent emergence ... More
A Two Weight Inequality for the Hilbert transform Assuming an Energy HypothesisJan 22 2010Mar 17 2011Subject to a range of side conditions, the two weight inequality for the Hilbert transform is characterized in terms of (1) a Poisson A_2 condition on the weights (2) A forward testing condition, in which the two weight inequality is tested on intervals ... More
Two Weight Inequalities for Maximal Truncations of Dyadic Calderón-Zygmund OperatorsNov 19 2009Mar 29 2011We consider L^p two weight inequalities for maximal truncations of dyadic Calderon-Zygmund operators. In the case of one weight being doubling, a characterization is given, and for the general case, sufficient conditions are given, including standard ... More
Two Weight Inequalities for Discrete Positive OperatorsNov 17 2009Nov 26 2010We characterize two weight inequalities for general positive dyadic operators. We consider both weak and strong type inequalities, and general (p,q) mapping properties. Special cases include Sawyers Fractional Integral operator results from 1988, and ... More
Nonequilibrium finite-frequency noise of a resonance-level quantum dot close to a dissipative quantum phase transition: Functional Renormalization Group approachesOct 25 2010Nov 15 2012We calculate the finite-frequency current noise of a nonequilibrium resonance-level quantum dot close to a dissipative quantum phase transition of the Kosterlitz-Thouless (KT) type between a de-localized phase for weak dissipation and a localized phase ... More
Dynamical properties of a nonequilibrium quantum dot close to localized-delocalized quantum phase transitionsAug 23 2010We calculate the dynamical decoherence rate and susceptibility of a nonequilibrium quantum dot close to the delocalized-to-localized quantum phase transitions. The setup concerns a resonance-level coupled to two spinless fermionic baths with a finite ... More
Optimal regularized inverse matrices for inverse problemsMar 18 2016In this paper, we consider optimal low-rank regularized inverse matrix approximations and their applications to inverse problems. We give an explicit solution to a generalized rank-constrained regularized inverse approximation problem, where the key novelties ... More
Neutral-current Neutrino-nucleus Scattering in Quasielastic RegionJul 10 2007Jul 20 2007The neutral-current neutrino-nucleus scattering is calculated through the neutrino-induced knocked-out nucleon process in the quasielastic region by using a relativistic single particle model for the bound and continuum states. The incident energy range ... More
Ultra-short pulses in linear and nonlinear mediaAug 10 2004We consider the evolution of ultra-short optical pulses in linear and nonlinear media. For the linear case, we first show that the initial-boundary value problem for Maxwell's equations in which a pulse is injected into a quiescent medium at the left ... More