Results for "Paul Beard"

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Directionality is an inherent property of biochemical networksJan 02 2007Feb 01 2007Thermodynamic constraints on reactions directions are inherent in the structure of a given biochemical network. However, concrete procedures for determining feasible reaction directions for large-scale metabolic networks are not well established. This ... More
Enhancing Compressed Sensing Photoacoustic Tomography by Simultaneous Motion EstimationFeb 14 2018A crucial limitation of current high-resolution 3D photoacoustic tomography (PAT) devices that employ sequential scanning is their long acquisition time. In previous work, we demonstrated how to use compressed sensing techniques to improve upon this: ... More
Enhancing Compressed Sensing 4D Photoacoustic Tomography by Simultaneous Motion EstimationFeb 14 2018Jun 15 2018A crucial limitation of current high-resolution 3D photoacoustic tomography (PAT) devices that employ sequential scanning is their long acquisition time. In previous work, we demonstrated how to use compressed sensing techniques to improve upon this: ... More
Model based learning for accelerated, limited-view 3D photoacoustic tomographyAug 31 2017Recent advances in deep learning for tomographic reconstructions have shown great potential to create accurate and high quality images with a considerable speed-up. In this work we present a deep neural network that is specifically designed to provide ... More
Approximate k-space models and Deep Learning for fast photoacoustic reconstructionJul 09 2018We present a framework for accelerated iterative reconstructions using a fast and approximate forward model that is based on k-space methods for photoacoustic tomography. The approximate model introduces aliasing artefacts in the gradient information ... More
Accelerated High-Resolution Photoacoustic Tomography via Compressed SensingApr 30 2016Sep 28 2016Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue. ... More
Acoustic Wave Field Reconstruction from Compressed Measurements with Application in Photoacoustic TomographySep 09 2016We present a method for the recovery of compressively sensed acoustic fields using patterned, instead of point-by-point, detection. From a limited number of such compressed measurements, we propose to reconstruct the field on the sensor plane in each ... More
Model based learning for accelerated, limited-view 3D photoacoustic tomographyAug 31 2017Mar 26 2018Recent advances in deep learning for tomographic reconstructions have shown great potential to create accurate and high quality images with a considerable speed-up. In this work we present a deep neural network that is specifically designed to provide ... More
New Experimental limit on Optical Photon Coupling to Neutral, Scalar BosonsJun 16 2008We report on the first results of a sensitive search for scalar coupling of photons to a light neutral boson in the mass range of approximately 1.0 milli-electron volts and coupling strength greater than 10$^-6$ GeV$^-1$ using optical photons. This was ... More
Metabolic Futile Cycles and Their Functions: A Systems Analysis of Energy and ControlNov 04 2005Jun 14 2006It has long been hypothesized that futile cycles in cellular metabolism are involved in the regulation of biochemical pathways. Following the work of Newsholme and Crabtree, we develop a quantitative theory for this idea based on open-system thermodynamics ... More
Relationship between Thermodynamic Driving Force and One-Way Fluxes in Reversible Chemical ReactionsJul 14 2006Nov 22 2006Chemical reaction systems operating in nonequilibrium open-system states arise in a great number of contexts, including the study of living organisms, in which chemical reactions, in general, are far from equilibrium. Here we introduce a theorem that ... More
Specification, Construction, and Exact Reduction of State Transition System Models of Biochemical ProcessesMar 15 2012Biochemical reaction systems may be viewed as discrete event processes characterized by a number of states and state transitions. These systems may be modeled as state transition systems with transitions representing individual reaction events. Since ... More
Simulations of Discrete Quantum Systems in Continuous Euclidean TimeFeb 29 1996Path integrals are usually formulated in discrete Euclidean time using the Trotter formula. We propose a new method to study discrete quantum systems, in which we work directly in the Euclidean time continuum. The method is of general interest and can ... More
An Overview of Particle Methods for Random Finite Set ModelsFeb 12 2016This overview paper describes the particle methods developed for the implementation of the a class of Bayes filters formulated using the random finite set formalism. It is primarily intended for the readership already familiar with the particle methods ... More
The dynamics of domain wall SkyrmionsMay 13 2013It has recently been shown that Skyrmions with a fixed size can exist in theories without a Skyrme term, providing the Skyrmion is located on a domain wall. Here we numerically compute domain wall Skyrmions of this type, in a (2+1)-dimensional O(3) sigma ... More
Run Time Approximation of Non-blocking Service Rates for Streaming SystemsApr 02 2015Apr 13 2015Stream processing is a compute paradigm that promises safe and efficient parallelism. Modern big-data problems are often well suited for stream processing's throughput-oriented nature. Realization of efficient stream processing requires monitoring and ... More
Automorphisms of $\mathscr{P}(λ)/\mathscr{I}_κ$Jun 10 2015Aug 27 2015We study conditions on automorphisms of Boolean algebras of the form $P(\lambda)/I_\kappa$ (where $\lambda$ is an uncountable cardinal and $I_\kappa$ is the ideal of sets of cardinality less than $\kappa$) which allow one to conclude that a given automorphism ... More
The Visible and Infrared Survey Telescope for Astronomy (VISTA): Design, Technical Overview and PerformanceSep 16 2014Mar 11 2015The Visible and Infrared Survey Telescope for Astronomy (VISTA) is the 4-metre wide-field survey telescope at ESO's Paranal Observatory, equipped with the world's largest near-infrared imaging camera (VISTA IR Camera, VIRCAM), with 1.65 degree diameter ... More
Efficient Cluster Algorithm for CP(N-1) ModelsFeb 14 2006Despite several attempts, no efficient cluster algorithm has been constructed for CP(N-1) models in the standard Wilson formulation of lattice field theory. In fact, there is a no-go theorem that prevents the construction of an efficient Wolff-type embedding ... More
An Efficient Cluster Algorithm for CP(N-1) ModelsOct 06 2005We construct an efficient cluster algorithm for ferromagnetic SU(N)-symmetric quantum spin systems. Such systems provide a new regularization for CP(N-1) models in the framework of D-theory, which is an alternative non-perturbative approach to quantum ... More
Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crustJul 25 2012We consider the astrophysical reaction rates for radiative neutron capture reactions ($n,\gamma$) in the crust of a neutron star. The presence of degenerate neutrons at high densities (mainly in the inner crust) can drastically affect the reaction rates. ... More
An annotated English translation of `Kinetics of stationary reactions' [M. I. Temkin, Dolk. Akad. Nauk SSSR. 152, 156 (1963)]Jan 16 2010Temkin's 1963 article on one-way fluxes and flux ratios in steady-state reaction systems bears directly on current research in physical and biological chemistry, such as in the interpretation of metabolic exchange fluxes determined from isotopomer labeling ... More
A simple analytic model for astrophysical S-factorsOct 12 2010We propose a physically transparent analytic model of astrophysical S-factors as a function of a center-of-mass energy E of colliding nuclei (below and above the Coulomb barrier) for non-resonant fusion reactions. For any given reaction, the S(E)-model ... More
A Lexicon for Underspecified Semantic TaggingMay 14 1997The paper defends the notion that semantic tagging should be viewed as more than disambiguation between senses. Instead, semantic tagging should be a first step in the interpretation process by assigning each lexical item a representation of all of its ... More
Semiparametric Efficiency of GMM under Approximate ConstraintsNov 22 2010Nov 23 2010Generalized empirical likelihood and generalized method of moments are well spread methods of resolution of inverse problems in econometrics. Each method defines a specific semiparametric model for which it is possible to calculate efficiency bounds. ... More
Discrepancy, separation and Riesz energy of finite point sets on compact connected Riemannian manifoldsMar 26 2014Jun 28 2014On a smooth compact connected $d$-dimensional Riemannian manifold $M$, if $0 < s < d$ then an asymptotically equidistributed sequence of finite subsets of $M$ that is also well-separated yields a sequence of Riesz $s$-energies that converges to the energy ... More
Self-field and magnetic-flux quantum mechanicsApr 06 2005Self-field and quantized magnetic-flux are employed to generate the quantum numbers n, m, and l of atomic physics. Wave-particle duality is shown to be a natural outcome of having a particle and its self-field.
Asyptotic Normality for Maximum Likelihood Estimation and Operational RiskAug 12 2015Aug 25 2016Operational risk models commonly employ maximum likelihood estimation (MLE) to fit loss data to heavy-tailed distributions. Yet several desirable properties of MLE (e.g. asymptotic normality) are generally valid only for large sample-sizes, a situation ... More
Transfert du pseudo-coefficient de Kottwitz et formules de caractere pour la serie discrete de GL(N) d'un corps localMar 30 2012Let G be the group GL(N,F), where F is a non-archimedean locally compact field. Using Bushnell and Kutzko's simple types, as well as an original idea of Henniart's, we construct explicit pseudo-coefficients for the discrete series representations of G. ... More
The equivariant pair-of-pants product in fixed point Floer cohomologyNov 10 2014May 31 2015The Floer cohomology of a symplectic automorphism and that of its square are related by the pair-of-pants product. For exact symplectic automorphisms, we introduce an equivariant version of that product, and use it to prove a Smith-type inequality of ... More
Lagrangian homology spheres in (A_m) Milnor fibres via C^*-equivariant A_infinity modulesFeb 09 2012Aug 08 2012We establish restrictions on Lagrangian embeddings of rational homology spheres into certain open symplectic manifolds, namely the (A_m) Milnor fibres of odd complex dimension. This relies on general considerations about equivariant objects in module ... More
Exact Lagrangian submanifolds of $T^*S^n$ and the graded Kronecker quiverJan 17 2004This short and fairly informal note is an attempt to explain how methods of homological algebra may be brought to bear on problems in symplectic geometry. We do this by looking at a familiar sample question, which is that of the topology of Lagrangian ... More
Homological mirror symmetry for the quartic surfaceOct 26 2003Aug 06 2013This proves Kontsevich's mirror conjecture for (on the symplectic side) a quartic surface in P^3.
Graded Lagrangian submanifoldsMar 09 1999May 31 2000In the usual setup, the grading on Floer homology is relative: it is unique only up to adding a constant. "Graded Lagrangian submanifolds" are Lagrangian submanifolds with a bit of extra structure, which fixes the ambiguity in the grading. The idea is ... More
Disjoinable Lagrangian spheres and dilationsJul 18 2013Oct 20 2013We consider open symplectic manifolds which admit dilations (in the sense previously introduced by Solomon and the author). We obtain restrictions on collections of Lagrangian submanifolds which are pairwise disjoint (or pairwise disjoinable by Hamiltonian ... More
On Those Analytic Functions of One Variable which possess an Algebraic Addition TheoremDec 26 2012This is a literal word-for-word translation from the German of the article by Paul Koebe which contains a proof of Weierstrass's famous theorem characterizing all analytic functions which possess an algebraic addition theorem.
Nesting Induced Large Magnetoelasticity in the Iron Arsenide SystemsDec 17 2013Sep 02 2014A novel feature of the iron arsenides is the magnetoelastic coupling between the long wavelength in-plane strains of the lattice and the collective spin fluctuations of the electrons near the magnetic ordering wavevectors. Here, we study its microscopic ... More
Interaction Correction of Conductivity Near a Ferromagnetic Quantum Critical PointSep 07 2007Nov 05 2008We calculate the temperature dependence of conductivity due to interaction correction for a disordered itinerant electron system close to a ferromagnetic quantum critical point which occurs due to a spin density wave instability. In the quantum critical ... More
Collective flow without hydrodynamics: simulation results for relativistic ion collisionsApr 10 2015Sep 14 2015Flow signatures in experimental data from relativistic ion collisions are usually interpreted as a fingerprint of the presence of a hydrodynamic phase during the evolution of these systems. In this work, flow signatures arising from event-by-event viscous ... More
Causal Viscous Hydrodynamics for Central Heavy-Ion Collisions II: Meson Spectra and HBT RadiiJan 11 2007Feb 16 2007Causal viscous hydrodynamic fits to experimental data for pion and kaon transverse momentum spectra from central Au+Au collisions at \sqrt{s_{NN}}=200 GeV are presented. Starting the hydrodynamic evolution at 1 fm/c and using small values for the relaxation ... More
Hyperspherical Partial Wave Theory with Two-term Error CorrectionFeb 14 2008Hyperspherical Partial Wave Theory has been applied to calculate T-matrix elements and Single Differential Cross-Section (SDCS) results for electron-hydrogen ionization process within Temkin-Poet model potential. We considered three different values of ... More
Recent Physics results with the COMPASS ExperimentNov 03 2005Nov 06 2005The COMPASS experiment has obtained first physics results in the field of polarized distribution functions for quarks and gluons using muon scattering off polarized deuterons. The analysis using open charm production and pairs of high $p_T$ hadrons is ... More
Selected Aspects of Neutron DecayApr 18 2005Precision measurements of neutron decay offer complementary access to particle physics at small distance scales or high energies. In particular they allow tests of the V-A structure of the weak interaction. Among many experimental activities which are ... More
Strangeness in Hadronic SystemsSep 23 1999This paper reviews different aspects of hadronic systems with strange quarks. It reviews production, spectroscopy and decay of baryons and hypernuclei with emphasis on recent results obtained in this field. It includes a comparison of different systems ... More
The Fermion Content of the Standard ModelOct 27 2014We describe a simple model that automatically generates the sum over gauge group representations and chiralities of a single generation of fermions in the Standard Model, augmented by a sterile neutrino. The model is a modification of the world-line approach ... More
Generating functions attached to some infinite matricesJun 10 2009Let V be an infinite matrix with rows and columns indexed by the positive integers, and entries in a field F. Suppose that v_{i,j} only depends on i-j and is 0 for |i-j| large. Then V^n is defined for all n, and one has a "generating function" G=\sum ... More
It was twenty years ago today ...Aug 14 2011Sep 13 2011To mark the 20th anniversary of the (14 Aug 1991) commencement of (now, I've adapted this article from one that first appeared in Physics World (2008), was later reprinted (with permission) in Learned Publishing (2009), ... More
Exponentiation of commuting nilpotent varietiesJun 22 2013Sep 20 2014Let $H$ be a linear algebraic group over an algebraically closed field of characteristic $p>0$. We prove that any "exponential map" for $H$ induces a bijection between the variety of $r$-tuples of commuting $[p]$-nilpotent elements in $Lie(H)$ and the ... More
Support Varieties for Frobenius Kernels of Classical GroupsJan 13 2012Sep 26 2012Let G be a simple classical algebraic group over an algebraically closed field of positive characteristic. We describe the support variety of a simple G-module over the r-th Frobenius kernel of G, in terms of its calculation over the first Frobenius kernel. ... More
Compactly generated quasitopological homotopy groups with discontinuous multiplicationMay 31 2011For each positive integer Q there exists a path connected metric compactum X such that the Qth-homotopy group of X is compactly generated but not a topological group (with the quotient topology).
Lemma 4: Haptic Input + Auditory Display = Musical Instrument?Nov 21 2013In this paper we look at some of the design issues that affect the success of multimodal displays that combine acoustic and haptic modalities. First, issues affecting successful sonification design are explored and suggestions are made about how the language ... More
Computing with Hereditarily Finite SequencesDec 16 2011e use Prolog as a flexible meta-language to provide executable specifications of some fundamental mathematical objects and their transformations. In the process, isomorphisms are unraveled between natural numbers and combinatorial objects (rooted ordered ... More
On Two Infinite Families of Pairing BijectionsJan 01 2013We describe two general mechanisms for producing pairing bijections (bijective functions defined from N x N to N). The first mechanism, using n-adic valuations results in parameterized algorithms generating a countable family of distinct pairing bijections. ... More
Declarative Combinatorics: Boolean Functions, Circuit Synthesis and BDDs in HaskellAug 06 2008We describe Haskell implementations of interesting combinatorial generation algorithms with focus on boolean functions and logic circuit representations. First, a complete exact combinational logic circuit synthesizer is described as a combination of ... More
Pairing Functions, Boolean Evaluation and Binary Decision Diagrams in PrologAug 05 2008Feb 04 2009A "pairing function" J associates a unique natural number z to any two natural numbers x,y such that for two "unpairing functions" K and L, the equalities K(J(x,y))=x, L(J(x,y))=y and J(K(z),L(z))=z hold. Using pairing functions on natural number representations ... More
Provably Manipulation-Resistant Reputation SystemsNov 05 2014We consider a community of users who must make periodic decisions about whether to interact with one another. We propose a protocol which allows honest users to reliably interact with each other, while limiting the damage done by each malicious or incompetent ... More
The Hawaiian earring group and metrizabilityMar 10 2006Endowed with quotient topology inherited from the space of based loops, the fundamental group of the Hawaiian earring fails to be metrizable. The fundamental group of any space which retracts to the Hawaiian earring is also nonmetrizable.
Absolute Algebra III - The saturated spectrumOct 31 2013Let B1 denote the set {0,1} with the usual operations except that $1+1=1$, in other words, the smallest characteristic 1 semifield . We compare two possible analogues of the notion of prime ideal for B1--algebras. We then consider the relations between ... More
Algèbre absolueNov 10 2009We give an exposition of Zhu's theory concerning a formal analogue of the field Fp, "for p = 1", and then compare it to Deitmar's.-- Nous exposons la th\'eorie de Zhu concernant un analogue formel du corps Fp "pour p = 1", et la comparons \`a celle de ... More
Qualitative Decision Making Under Possibilistic Uncertainty: Toward more discriminating criteriaJul 04 2012The aim of this paper is to propose a generalization of previous approaches in qualitative decision making. Our work is based on the binary possibilistic utility (PU), which is a possibilistic counterpart of Expected Utility (EU).We first provide a new ... More
The Evolution of AGN in Groups and ClustersOct 08 2009The evolution of AGN in groups and clusters provides important information about how their black holes grow, the extent to which galaxies and black holes coevolve in dense environments, and has implications for feedback in the local universe and at the ... More
Symplectic packing in dimension 4Jun 06 1996Jun 09 1996We discuss closed symplectic 4-manifolds which admit full symplectic packings by $N$ equal balls for large $N$'s. We give a homological criterion for recognizing such manifolds. As a corollary we prove that ${\Bbb C}P^2$ can be fully packed by $N$ equal ... More
Noncommutative String Theory, the R-Matrix, and Hopf AlgebrasNov 04 1999Motivated by the form of the noncommutative *-product in a system of open strings and Dp-branes with constant nonzero Neveu-Schwarz 2-form, we define a deformed multiplication operation on a quasitriangular Hopf algebra in terms of its R-matrix, and comment ... More
Ward Identities and Anomalies in Pure W_4 GravitySep 11 1998Feb 12 1999W_4 gravity is treated algebraically, represented by a set of transformations on classical fields. The Ward identities of the theory are determined by requiring the algebra to close. The general forms for the anomalies are found by looking for solutions ... More
Derivatives and the Role of the Drinfel'd Twist in Noncommutative String TheoryMar 26 2000Mar 29 2000We consider the derivatives which appear in the context of noncommutative string theory. First, we identify the correct derivations to use when the underlying structure of the theory is a quasitriangular Hopf algebra. Then we show that this is a specific ... More
Effects of mathematical locality and number scaling on coordinate chart useMay 13 2014A stronger foundation for earlier work on the effects of number scaling, and local mathematics is described. Emphasis is placed on the effects of scaling on coordinate systems. Effects of scaling are represented by a scalar field, $\theta,$ that appears ... More
Fields of Iterated Quantum Reference Frames based on Gauge Transformations of Rational String StatesApr 18 2006This work is based on a description of quantum reference frames that seems more basic than others in the literature. Here a frame is based on a set of real and of complex numbers and a space time as a 4-tuple of the real numbers. There are many isomorphic ... More
A representation of complex rational numbers in quantum mechanicsMar 16 2005Jun 20 2005A representation of complex rational numbers in quantum mechanics is described that is not based on logical or physical qubits. It stems from noting that the zeros in a product qubit state do not contribute to the number. They serve only as place holders. ... More
Tightening the Theory-Experiment Connection in Physics: R_{n} based Space and TimeAug 11 2004Some aspects of replacing C based physics by C_{n} based physics are discussed. Here C_{n} ={R_{n},I_{n}} where R_{n} and I_{n} are the real and imaginary components of the numbers in C_{n}, and both R_{n} and I_{n}) are sets of length 2n string numbers ... More
The Representation of Numbers by States in Quantum MechanicsSep 29 2000The representation of numbers by tensor product states of composite quantum systems is examined. Consideration is limited to k-ary representations of length L and arithmetic modulo k^{L}. An abstract representation on an L fold tensor product Hilbert ... More
Dynamics of Induced Surfaces in Four-Dimensional Euclidean SpaceDec 15 2006The Davey Stewartson hierarchy will be developed based on a set of three matrix differential operators. These equations will act as evolution equations for different types of surface deformation in Euclidean four space. The Weierstrass representation ... More
Closed Unitary and Similarity Orbits of Normal Operators in Purely Infinite C*-AlgebrasAug 31 2012Nov 29 2012We will investigate the norm closure of the unitary and similarity orbits of normal operators in unital, simple, purely infinite C*-algebras. An operator theoretic proof will be given to the classification of when two normal operators are approximately ... More
Cyclic MonopolesOct 06 1996We study charge k SU(2) BPS monopoles which are symmetric under the cyclic group of order k. Approximate twistor data (spectral curves and Nahm data) is constructed using a new technique based upon a Painleve analysis of Nahm's equation around a pole. ... More
Knots in the Skyrme-Faddeev modelMay 10 2007The Skyrme-Faddeev model is a modified sigma model in three-dimensional space, which has string-like topological solitons classified by the integer-valued Hopf charge. Numerical simulations are performed to compute soliton solutions for Hopf charges up ... More
Kink Chains from Instantons on a TorusSep 29 1994We describe how the procedure of calculating approximate solitons from instanton holonomies may be extended to the case of soliton crystals. It is shown how sine-Gordon kink chains may be obtained from CP1 instantons on a torus. These kink chains turn ... More
Spanning Trees in Grid GraphsSep 15 2008Building on work by Desjarlais, Molina, Faase, and others, a general method is obtained for counting the number of spanning trees of graphs that are a product of an arbitrary graph and either a path or a cycle, of which grid graphs are a subclass. Results ... More
Analyticity of strictly static and strictly stationary, inheriting and non-inheriting Einstein-Maxwell solutionsApr 19 2007Following the technique of M\"uller-zum-Hagen, refs [1,2], we show that strictly static and strictly stationary solutions of the Einstein-Maxwell equations are analytic in harmonic coordinates. This holds whether or not the Maxwell field inherits the ... More
A comment on positive mass for scalar field sourcesMay 31 2011We use a transformation due to Bekenstein to relate the ADM and Bondi masses of asymptotically-flat solutions of the Einstein equations with, respectively, scalar sources and conformal-scalar sources. Although the conformal-scalar energy-momentum tensor ... More
Conditions for nonexistence of static or stationary, Einstein-Maxwell, non-inheriting black-holesNov 05 2006We consider asymptotically-flat, static and stationary solutions of the Einstein equations representing Einstein-Maxwell space-times in which the Maxwell field is not constant along the Killing vector defining stationarity, so that the symmetry of the ... More
A Note on Riemannian Anti-self-dual Einstein metrics with SymmetrySep 11 2006We give a complete proof of the result stated in an earlier article, that the general Einstein metric with a symmetry, an anti-self-dual Weyl tensor and nonzero scalar curvature is determined by a solution of the $SU(\infty)$-Toda field equation. We consider ... More
Two linear transformations each tridiagonal with respect to an eigenbasis of the otherJun 27 2004Let $K$ denote a field and let $V$ denote a vector space over $K$ with finite positive dimension. We consider a pair of linear transformations $A:V\to V$ and $A^*:V\to V$ that satisfy both conditions below: (i) There exists a basis for $V$ with respect ... More
GL(2,R)-Invariant Measures in Marked Strata: Generic Marked Points, Earle-Kra for Strata, and IlluminationJan 28 2016Let H be a component of a stratum of abelian differentials and let H(m,n) be the collection of translation surfaces in H together with m+n distinct marked points, none coinciding with zeros, m of which are labelled and n of which are unlabelled. We show ... More
On Integrability of Type 0A Matrix Model in the Presence of D braneJan 11 2011We consider type 0A matrix model in the presence of a spacelike D brane,localized in matter direction at any arbitrary point. It appears that in order to have an appropriate string/MQM correspondence we must need to impose a constraint on the matrix model ... More
Parton Propagation in a Gluon FieldFeb 22 2005The phenomenological success of PQCD is based on processes where the effects of the color field environment on parton propagation can be eliminated or is universal. In hard diffraction and quarkonium production the PQCD subprocess is the same as in fully ... More
The Unexpected Role of Final State Interactions in Deep Inelastic ScatteringJul 21 2003Rescattering of the struck quark in Deep Inelastic Scattering implies that measured parton distributions are not directly related to the Fock state probabilities of the target wave function. The production amplitudes acquire dynamical phases, which gives ... More
Confinement with Perturbation Theory, after All?Sep 16 2014Nov 17 2014I call attention to the possibility that QCD bound states (hadrons) could be derived using rigorous Hamiltonian, perturbative methods. Solving Gauss' law for $A^0$ with a non-vanishing boundary condition at spatial infinity gives an \order{\alpha_s^0} ... More
Are hadrons simpler than they seem?Mar 07 2013I briefly review a systematic approximation scheme of QCD in which the quark model picture of hadrons emerges at lowest order. A linear A^0 potential arises if Gauss' law is solved with a non-vanishing boundary condition at spatial infinity. Similarly ... More
Measuring transverse size with virtual photonsOct 15 2011Fourier transforming the virtual photon transverse momentum in \gamma*(q)+N \to f processes allows new insight into hadron dynamics as a function of impact parameter b. I discuss how previous analyses of charge density based on elastic and transition ... More
Soft Perturbative QCDAug 30 1999There are indications of a faith transition in QCD: The strong coupling may freeze at a sufficiently low value to make PQCD relevant even in the confining regime. The properties of PQCD at low Q^2 depend on the asymptotic field configuration assumed at ... More
Entropy of Overcomplete Kernel DictionariesNov 01 2014In signal analysis and synthesis, linear approximation theory considers a linear decomposition of any given signal in a set of atoms, collected into a so-called dictionary. Relevant sparse representations are obtained by relaxing the orthogonality condition ... More
An eigenanalysis of data centering in machine learningJul 10 2014Many pattern recognition methods rely on statistical information from centered data, with the eigenanalysis of an empirical central moment, such as the covariance matrix in principal component analysis (PCA), as well as partial least squares regression, ... More
Approximation errors of online sparsification criteriaSep 21 2014Many machine learning frameworks, such as resource-allocating networks, kernel-based methods, Gaussian processes, and radial-basis-function networks, require a sparsification scheme in order to address the online learning paradigm. For this purpose, several ... More
Analyzing sparse dictionaries for online learning with kernelsSep 21 2014Many signal processing and machine learning methods share essentially the same linear-in-the-parameter model, with as many parameters as available samples as in kernel-based machines. Sparse approximation is essential in many disciplines, with new challenges ... More
Structure of the Standard ModelApr 19 2003The structure of the standard model is concisely summarized, including the standard model Lagrangian, spontaneous symmetry breaking, the reexpression of the Lagrangian in terms of mass eigenstates after symmetry breaking, and the gauge interactions. The ... More
Time Variation of Fundamental Constants as a Probe of New PhysicsApr 09 2003Apr 10 2003Time variation of fundamental constants would not be surprising in the framework of theories involving extra dimensions. The variation of any one constant is likely to be correlated with variations of others in a pattern that is diagnostic of the underlying ... More
Alternatives to the Seesaw: Extra Z's and Constraints on Large Extra DimensionsApr 04 2003Apr 10 2003Alternatives to the traditional grand unified theory seesaw for neutrino masses are briefly described. These include the possibility of large extra dimensions and various possibilities for models involving an extra U(1)' gauge symmetry. The difficulty ... More
Neutrino Oscillation Workshop 2000: Conference SummaryJan 22 2001The NOW2000 Workshop summarized the present status and future possibilities for all aspects of neutrino physics and astrophysics. Neutrino oscillation physics has truly come of age in the last few years. It is now data driven (analogous to cosmology and ... More
Theoretical Summary, Electroweak PhysicsMay 20 1999Aspects of theoretical electroweak physics are summarized, including the status of electroweak radiative corrections, the hadronic contribution to the running of alpha, global fits to precision data and their implication for testing the standard model ... More
Theoretical Study of the Electroweak Interaction -- Present and FutureAug 17 1994There have been several important recent developments in precision electroweak tests. These include: the new LEP energy scan during the 1993 run; the first high-precision results on the left-right asymmetry from the SLD Collaboration at SLAC; the probable ... More
Solar NeutrinosMar 10 1993The status of solar neutrino experiments and their implications for both nonstandard astrophysics ({\it e.g.,} cool sun models) and nonstandard neutrino properties ({\it e.g.,} MSW conversions) are discussed. Assuming that all of the experiments are correct, ... More