Results for "John van de Wetering"

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Entailment Relations on DistributionsAug 04 2016In this paper we give an overview of partial orders on the space of probability distributions that carry a notion of information content and serve as a generalisation of the Bayesian order given in (Coecke and Martin, 2011). We investigate what constraints ... More
Graph-theoretic Simplification of Quantum Circuits with the ZX-calculusFeb 08 2019We present a new circuit-to-circuit optimisation routine based on an equational theory called the ZX-calculus. We first interpret quantum circuits as ZX-diagrams, a flexible, lower-level language for describing quantum computations graphically. Then, ... More
Probing photo-ionization: Experiments on positive streamers in pure gasses and mixturesDec 04 2009Feb 08 2010Positive streamers are thought to propagate by photo-ionization whose parameters depend on the nitrogen:oxygen ratio. Therefore we study streamers in nitrogen with 20%, 0.2% and 0.01% oxygen and in pure nitrogen, as well as in pure oxygen and argon. Our ... More
Spontaneous symmetry breaking of (1+1)-dimensional $\bf φ^4$ theory in light-front field theory (III)Sep 03 1994We investigate (1+1)-dimensional $\phi^4$ field theory in the symmetric and broken phases using discrete light-front quantization. We calculate the perturbative solution of the zero-mode constraint equation for both the symmetric and broken phases and ... More
Subgeometries in the André/Bruck-Bose representationSep 22 2014We consider the Andr\'e/Bruck-Bose representation of the projective plane $\mathrm{PG}(2,q^n)$ in $\mathrm{PG}(2n,q)$. We investigate the representation of $\mathbb{F}_{q^k}$-sublines and $\mathbb{F}_{q^k}$-subplanes of $\mathrm{PG}(2,q^n)$, extending ... More
First-Principles Calculations of Luminescence Spectrum Line Shapes for Defects in Semiconductors: The Example of GaN and ZnOMar 12 2013We present a theoretical study of broadening of defect luminescence bands due to vibronic coupling. Numerical proof is provided for the commonly used assumption that a multi-dimensional vibrational problem can be mapped onto an effective one-dimensional ... More
Role of excited states in Shockley-Read-Hall recombination in wide-band-gap semiconductorsMay 18 2016Defect-assisted recombination is an important limitation on efficiency of optoelectronic devices. However, since nonradiative capture rates decrease exponentially with energy of the transition, the mechanisms by which such recombination can take place ... More
H$α$ Imaging spectroscopy of Balmer-dominated shocks in Tycho's supernova remnantSep 12 2016We present Fabry-P\'erot interferometric observations of the narrow H$\alpha$ component in the shock front of the historical supernova remnant Tycho (SN 1572). Using GH$\alpha$FaS (Galaxy H$\alpha$ Fabry-P\'erot Spectrometer) on the William Herschel Telescope, ... More
Clean and As-covered zinc-blende GaN (001) surfaces: Novel surface structures and surfactant behaviorMay 13 1997Mar 31 1998We have investigated clean and As-covered zinc-blende GaN (001) surfaces, employing first-principles total-energy calculations. For clean GaN surfaces our results reveal a novel surface structure very different from the well-established dimer structures ... More
A generalization of Jaynes' principle: an information-theoretic interpretation of the minimum principles of quantum mechanics and gravitationJan 18 2000By considering the "kinetic-energy" term of the minimum principle for the Schr\"{o}dinger equation as a measure of information, that minimum principle is viewed as a statistical estimation procedure, analogous to the manner in which Jaynes ({\it Phys. ... More
The Boltzmann/Shannon entropy as a measure of correlationJan 17 2000IIt is demonstrated that the entropy of statistical mechanics and of information theory, $S({\bf p}) = -\sum p_i \log p_i $ may be viewed as a measure of correlation. Given a probability distribution on two discrete variables, $p_{ij}$, we define the ... More
Non-linear connections on phase space and the Lorentz force lawJan 26 2000The equations of parallel transport for a non-linear connection on phase space are examined. It is shown that, for a free-particle Lagrangian, the connection term first-order in momentum reproduces the geodesic equation of General Relativity and the term ... More
Rapid detection of coherent tunneling in an InAs nanowire quantum dot through dispersive gate sensingDec 20 2018Dispersive sensing is a powerful technique that enables scalable and high-fidelity readout of solid-state quantum bits. In particular, gate-based dispersive sensing has been proposed as the readout mechanism for future topological qubits, which can be ... More
A Graph Signal Processing View on Functional Brain ImagingSep 29 2017Jan 29 2018Modern neuroimaging techniques provide us with unique views on brain structure and function; i.e., how the brain is wired, and where and when activity takes place. Data acquired using these techniques can be analyzed in terms of its network structure ... More
Early stages of ramified growth in quasi-two-dimensional electrochemical depositionDec 22 1995I have measured the early stages of the growth of branched metal aggregates formed by electrochemical deposition in very thin layers. The growth rate of spatial Fourier modes is described qualitatively by the results of a linear stability analysis [D.P. ... More
Bose polarons in the strongly interacting regimeMay 03 2016When an impurity is immersed in a Bose-Einstein condensate, impurity-boson interactions are expected to dress the impurity into a quasiparticle, the Bose polaron. We superimpose an ultracold atomic gas of $^{87}$Rb with a much lower density gas of fermionic ... More
A Slow-Growing Sequence Defined by an Unusual RecurrenceFeb 22 2006The sequence starts with a(1) = 1; to extend it one writes the sequence so far as XY^k, where X and Y are strings of integers, Y is nonempty and k is as large as possible: then the next term is k. The sequence begins 1, 1, 2, 1, 1, 2, 2, 2, 3, 1, 1, 2, ... More
Singular perturbation of quantum stochastic differential equations with coupling through an oscillator modeSep 06 2006We consider a physical system which is coupled indirectly to a Markovian resevoir through an oscillator mode. This is the case, for example, in the usual model of an atomic sample in a leaky optical cavity which is ubiquitous in quantum optics. In the ... More
KdV type hierarchies, the string equation and $W_{1+\infty}$ constraintsMar 15 1994May 17 1994To every partition $n=n_1+n_2+\cdots+n_s$ one can associate a vertex operator realization of the Lie algebras $a_{\infty}$ and $\hat{gl}_n$. Using this construction we make reductions of the $s$--component KP hierarchy, reductions which are related to ... More
Weakly decomposable regularization penalties and structured sparsityApr 21 2012Dec 10 2012It has been shown in literature that the Lasso estimator, or l1-penalized least squares estimator, enjoys good oracle properties. This paper examines which special properties of the l1-penalty allow for sharp oracle results, and then extends the situation ... More
An Integral View of Fast Shocks around Supernova 1006Feb 18 2013Jan 26 2015Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ~ 1000 km/s into the ambient, tenuous interstellar medium, producing ... More
Piecewise Flat Gravity in 3+1 dimensionsNov 28 2011We study a model for gravity in 3+1 dimensions, inspired in general relativity in 2+1 dimensions. In contrast regular general relativity in 3+1 dimensions, the model postulates that space in absence of matter is flat. The requirement that the Einstein ... More
Exact Piecewise Flat Gravitational WavesJun 27 2011Nov 20 2011We generalize our previous linear result [1] in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to construct ... More
Resonantly enhanced kicks from equatorial small mass-ratio inspiralsJun 10 2014Aug 19 2014We calculate the kick generated by an eccentric black hole binary inspiral as it evolves through a resonant orbital configuration where the precession of the system temporarily halts. As a result, the effects of the asymmetric emission of gravitational ... More
The Peculiar-Velocity-Field in Structure Formation Theories with Cosmic StringsOct 29 1997We investigate the peculiar velocity field due to long cosmic strings in several cosmological models and analyse the influence of a nonscaling behaviour of the string network, which is expected in open cosmological models or models with a cosmological ... More
Steering Macro-Scale Network Community Structure by Micro-Scale FeaturesMar 17 2016Network science plays an increasingly important role to model complex data in many scientific disciplines. One notable feature of network organization is community structure, which refers to clusters of tightly interconnected nodes. A prominent problem ... More
The $[n_1,n_2,\ldots,n_s]$--th reduced KP hierarchy and $W_{1+\infty}$ constraintsNov 10 1994To every partition $n=n_1+n_2+\cdots+n_s$ one can associate a vertex operator realization of the Lie algebras $a_{\infty}$ and $\hat{gl}_n$. Using this construction we obtain reductions of the $s$--component KP hierarchy, reductions which are related ... More
Voids and the Cosmic Web: cosmic depressions & spatial complexityNov 03 2016Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do they represent a key constituent of the Cosmic Web, they also are one of the cleanest probes and measures of global cosmological parameters. The shape and ... More
Phase properties of exponentially-fitted symmetric multistep methods for y''=f(x,y)Nov 26 2006A convenient tool to obtain numerical methods specially tuned on oscillating functions is exponential fitting. Such methods are needed in various branches of natural sciences, particularly in physics, since a lot of physical phenomena exhibit a pronounced ... More
Statistical Theory for High-Dimensional ModelsSep 30 2014These lecture notes consist of three chapters. In the first chapter we present oracle inequalities for the prediction error of the Lasso and square-root Lasso and briefly describe the scaled Lasso. In the second chapter we establish asymptotic linearity ... More
Discussion of ``2004 IMS Medallion Lecture: Local Rademacher complexities and oracle inequalities in risk minimization'' by V. KoltchinskiiAug 01 2007Discussion of ``2004 IMS Medallion Lecture: Local Rademacher complexities and oracle inequalities in risk minimization'' by V. Koltchinskii [arXiv:0708.0083]
Collisions in piecewise flat gravity in 3+1 dimensionsFeb 19 2010We consider the (3+1)-dimensional locally finite gravity model proposed by 't Hooft. In particular we revisit the problem of resolving collisions of string defects. We provide a new geometric description of the configurations of strings using piecewise ... More
Cosmic Strings and Structure FormationOct 26 1998We discuss structure formation in cosmic string theories. Emphasis is laid on the properties of the peculiar velocity field, non-gaussian features and clusters of galaxies. It is found that the predicted peculiar velocity field is quiet ($v<150$ km/s ... More
Twisted Toroidal Lie AlgebrasJun 14 2001Using $n$ finite order automorphisms on a simple complex Lie algebra we construct twisted $n$-toroidal Lie algebras. Thus obtaining Lie algebras wich have a rootspace decomposition. For the case $n=2$ we list certain simple Lie algebras and their automorphisms, ... More
The vector k-constrained KP hierarchy and Sato's GrassmannianAug 30 1996We use the representation theory of the infinite matrix group to show that (in the polynomial case) the $n$--vector $k$--constrained KP hierarchy has a natural geometrical interpretation on Sato's infinite Grassmannian. This description generalizes the ... More
Worst possible sub-directions in high-dimensional modelsMar 27 2014We examine the rate of convergence of the Lasso estimator of lower dimensional components of the high-dimensional parameter. Under bounds on the $\ell_1$-norm on the worst possible sub-direction these rates are of order $\sqrt {|J| \log p / n }$ where ... More
Shuffled equi-n-squaresJan 09 2017A formal n-square is the set of positions in an square matrix of size n. A shuffle of a formal n-square consists of independent rotations of each row and of each column. A key result turns out to be valid at least for n <= 34 and n = 37: Each set of n ... More
Gravitational self-force on eccentric equatorial orbits around a Kerr black holeJun 20 2016Aug 17 2016This paper presents the first calculation of the gravitational self-force on a small compact object on an eccentric equatorial orbit around a Kerr black hole to first order in the mass-ratio. That is the pointwise correction to the object's equations ... More
Galaxy growth from redshift 5 to 0 at fixed comoving number densityJul 06 2016Studying the average properties of galaxies at a fixed comoving number density over a wide redshift range has become a popular observational method, because it may trace the evolution of galaxies statistically. We test this method by comparing the evolution ... More
The Geometry of Massless Cosmic StringsNov 19 2012Jan 29 2013We study the geometry generated by a massless cosmic string. We find that this is given by a Riemann flat spacetime with a conical singularity along the worldsheet of the string. The geometry of such a spacetime is completely fixed by the holonomy of ... More
Piecewise Flat Gravitational WavesDec 09 2010Feb 22 2011We examine the continuum limit of the piecewise flat locally finite gravity model introduced by 't Hooft. In the linear weak field limit we find the energy--momentum tensor and metric perturbation of an arbitrary configuration of defects. The energy--momentum ... More
Noncanonical number systems in the integersApr 14 2008The well known binary and decimal representations of the integers, and other similar number systems, admit many generalisations. Here, we investigate whether still every integer could have a finite expansion on a given integer base b, when we choose a ... More
Self-force corrections to the periapsis advance around a spinning black holeOct 11 2016The linear in mass ratio correction to the periapsis advance of equatorial orbits around a spinning black hole is calculated for the first time and to very high precision, providing a key benchmark for different approaches modelling spinning binaries. ... More
Generic chaining and the l1-penaltyMay 16 2012We address the choice of the tuning parameter $\lambda$ in $\ell_1$-penalized M-estimation. Our main concern is models which are highly nonlinear, such as the Gaussian mixture model. The number of parameters $p$ is moreover large, possibly larger than ... More
Multicomponent multisublattice alloys, nonconfigurational entropy and other additions to the Alloy Theoretic Automated ToolkitJun 08 2009A number of new functionalities have been added to the Alloy Theoretic Automated Toolkit (ATAT) since it was last reviewed in this journal in 2002. ATAT can now handle multicomponent multisublattice alloy systems, nonconfigurational sources of entropy ... More
Voids and the Cosmic Web: cosmic depressions & spatial complexityNov 03 2016Nov 13 2016Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do they represent a key constituent of the Cosmic Web, they also are one of the cleanest probes and measures of global cosmological parameters. The shape and ... More
The Effect of Galactic Feedback on Gas Accretion and Wind RecyclingDec 02 2016In the absence of galactic winds, the rate at which gas accretes onto galaxies is determined by the gravitational potential and by radiative cooling. However, outflows driven by supernovae and active galactic nuclei not only eject gas from galaxies, but ... More
Consciousness is Pattern RecognitionMay 04 2016Jun 28 2016This is a proof of the strong AI hypothesis, i.e. that machines can be conscious. It is a phenomenological proof that pattern-recognition and subjective consciousness are the same activity in different terms. Therefore, it proves that essential subjective ... More
A low upper mass limit for the central black hole in the late-type galaxy NGC 4414Oct 13 2016We present our mass estimate of the central black hole in the isolated spiral galaxy NGC 4414. Using natural guide star adaptive optics assisted observations with the Gemini Near-Infrared Integral Field Spectrometer (NIFS) and the natural seeing Gemini ... More
Twisted GL_n Loop Group Orbit and Solutions of the WDVV EquationsApr 12 2000Apr 13 2000We show that all (n-component) KP tau-functions, which are related to the twisted loop group of $GL_n$, give solutions of the Darboux-Egoroff system of PDE's. Using the Geometry of the Grassmannian we construct from the corresponding wave function the ... More
The Adler-Shiota-van Moerbeke formula for the BKP hierarchyNov 22 1994We study the BKP hierarchy and prove the existence of an Adler--Shiota--van Moerbeke formula. This formula relates the action of the $BW_{1+\infty}$--algebra on tau--functions to the action of the ``additional symmetries'' on wave functions.
The $n$--TH Reduced BKP Hierarchy, the String Equation and $BW_{1+\infty}$--ConstraintsNov 10 1994We study the BKP hierarchy and its $n$--reduction, for the case that $n$ is odd. This is related to the principal realization of the basic module of the twisted affine Lie algebra $\hat{sl}_n^{(2)}$. We show that the following two statements for a BKP ... More
The $W_{1+\infty}(gl_s)$--symmetries of the $S$--component KP hierarchyNov 10 1994Adler, Shiota and van Moerbeke obtained for the KP and Toda lattice hierarchies a formula which translates the action of the vertex operator on tau--functions to an action of a vertex operator of pseudo-differential operators on wave functions. This relates ... More
Matrix integrals and the geometry of spinorsSep 29 1999Apr 01 2001We obtain the collection of symmetric and symplectic matrix integrals and the collection of Pfaffian tau-functions, recently described by Peng and Adler and van Moerbeke, as specific elements in the Spin-group orbit of the vacuum vector of a fermionic ... More
Conditions for Sustained Orbital Resonances in Extreme Mass Ratio InspiralsNov 18 2013May 09 2014We investigate the possibility of sustained orbital resonances in extreme mass ratio inspirals. Using a near-identity averaging transformation, we reduce the equations of motion for a particle moving in Kerr spacetime with self-force corrections in the ... More
On Gravity, Holography and the QuantumJan 17 2000Jan 20 2000The holographic principle states that the number of degrees of freedom describing the physics inside a volume (including gravity) is bounded by the area of the boundary (also called the screen) which encloses this volume. A stronger statement is that ... More
Cosmic String Network Evolution in arbitrary Friedmann-Lemaitre modelsMay 26 1997We use the velocity-dependent one-scale model by Martins & Shellard to investigate the evolution of a GUT long cosmic string network in arbitrary Friedmann-Lemaitre models. Four representative models are used to show that in general there is no scaling ... More
Studies Supporting PMT Characterization for the IceCube Collaboration: Precise Photodiode CalibrationNov 07 2015A laboratory set-up has been developed to more precisely measure the DOM optical sensitivity as a function of angle and wavelength. DOMs are calibrated in water using a broad beam of light whose intensity is measured with a NIST calibrated photodiode. ... More
On the uniform convergence of empirical norms and inner products, with application to causal inferenceOct 21 2013Uniform convergence of empirical norms - empirical measures of squared functions - is a topic which has received considerable attention in the literature on empirical processes. The results are relevant as empirical norms occur due to symmetrization. ... More
The (n,1)-Reduced DKP Hierarchy, the String Equation and W ConstraintsJun 13 2013Jan 15 2014The total descendent potential of a simple singularity satisfies the Kac-Wakimoto principal hierarchy. Bakalov and Milanov showed recently that it is also a highest weight vector for the corresponding W-algebra. This was used by Liu, Yang and Zhang to ... More
A low upper mass limit for the central black hole in the late-type galaxy NGC 4414Oct 13 2016Oct 24 2016We present our mass estimate of the central black hole in the isolated spiral galaxy NGC 4414. Using natural guide star adaptive optics assisted observations with the Gemini Near-Infrared Integral Field Spectrometer (NIFS) and the natural seeing Gemini ... More
An active, asynchronous companion to a redback millisecond pulsarSep 26 2016PSR\,J1723$-$2837 is a "redback" millisecond pulsar (MSP) with a low-mass companion in a 14.8\,h orbit. The system's properties closely resemble those of "transitional" MSPs that alternate between spin-down and accretion-powered states. In this paper ... More
The Arab Spring: A Simple Compartmental Model for the Dynamics of a RevolutionOct 05 2012The self-immolation of Mohamed Bouazizi on December 17, 2011 in the small Tunisian city of Sidi Bouzid, set off a sequence of events culminating in the revolutions of the Arab Spring. It is widely believed that the Internet and social media played a critical ... More
LOFAR: Early imaging results from commissioning for Cygnus AJun 06 2011The Low Frequency Array (LOFAR) will operate between 10 and 250 MHz, and will observe the low frequency Universe to an unprecedented sensitivity and angular resolution. The construction and commissioning of LOFAR is well underway, with over 27 of the ... More
An Integral View of Balmer-dominated Shocks in Supernova RemnantsJul 30 2013We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 km/s) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution of the instrument ... More
A Probabilistic Modeling Approach to Hearing Loss CompensationFeb 03 2016Sep 06 2016Hearing Aid (HA) algorithms need to be tuned ("fitted") to match the impairment of each specific patient. The lack of a fundamental HA fitting theory is a strong contributing factor to an unsatisfying sound experience for about 20% of hearing aid patients. ... More
A multi-wavelength interferometric study of the massive young stellar object IRAS 13481-6124Nov 10 2015We present new mid-infrared interferometric observations of the massive young stellar object IRAS 13481-6124, using VLTI/MIDI for spectrally-resolved, long-baseline measurements (projected baselines up to $\sim120$ m) and GSO/T-ReCS for aperture-masking ... More
Magnetism and exchange interaction of small rare-earth clusters; Tb as a representativeMay 31 2016Here we follow, both experimentally and theoretically, the development of magnetism in Tb clusters from the atomic limit, adding one atom at a time. The exchange interaction is, surprisingly, observed to drastically increase compared to that of bulk, ... More
On non-asymptotic bounds for estimation in generalized linear models with highly correlated designSep 06 2007We study a high-dimensional generalized linear model and penalized empirical risk minimization with $\ell_1$ penalty. Our aim is to provide a non-trivial illustration that non-asymptotic bounds for the estimator can be obtained without relying on the ... More
The symmetries of the 2phi1Jul 02 2008We show that the only symmetries of the 2phi1 within a large class of possible transformations are Heine's transformations. The class of transformations considered consists of equation of the form 2phi1(a,b;c;q,z)= f(a,b,c,z) 2phi1(L(a,b,c,q,z)), where ... More
A variety that cannot be dominated by one that liftsFeb 21 2019We prove a precise version of a theorem of Siu and Beauville on morphisms to higher genus curves, and use it to show that if a variety $X$ in characteristic $p$ lifts to characteristic $0$, then any morphism $X \to C$ to a curve of genus $g \geq 2$ can ... More
The Third Stromlo Symposium - The Galactic Halo: Bright Stars and Dark MatterJan 29 1999This summary discribes the highlights of the Third Stromlo Symposium, on the nature of the stellar, gaseous, and dark components of the Galactic Halo.
Reflection and transmission at dimensional boundariesAug 16 2006An inhomogeneous Kaluza-Klein compactification of a higher dimensional spacetime may give rise to an effective 4d spacetime with distinct domains having different sizes of the extra dimensions. The domains are separated by domain walls generated by the ... More
Progress with the LOFAR Imaging PipelineAug 27 2010One of the science drivers of the new Low Frequency Array (LOFAR) is large-area surveys of the low-frequency radio sky. Realizing this goal requires automated processing of the interferometric data, such that fully calibrated images are produced by the ... More
Robust and parallel scalable iterative solutions for large-scale finite cell analysesSep 04 2018Sep 05 2018The finite cell method is a highly flexible discretization technique for numerical analysis on domains with complex geometries. By using a non-boundary conforming computational domain that can be easily meshed, automatized computations on a wide range ... More
Ruijsenaars' hypergeometric function and the modular double of U_q(sl(2,C))Jan 24 2005Sep 19 2006Simultaneous eigenfunctions of two Askey-Wilson second order difference operators are constructed as formal matrix coefficients of the principal series representation of the modular double of the quantized universal enveloping algebra U_q(sl(2,C)). These ... More
The CKM matrix and flavor physics from lattice QCDNov 16 2009I discuss the role of lattice QCD in testing the Standard Model and searching for physics beyond the Standard Model in the quark flavor sector. I first review the Standard Model CKM framework. I then present the current status of the CKM matrix, focusing ... More
Factors of disconnected graphs and polynomials with nonnegative integer coefficientsMar 03 2011We investigate the uniqueness of factorisation of possibly disconnected finite graphs with respect to the Cartesian, the strong and the direct product. It is proved that if a graph has $n$ connected components, where $n$ is prime, or $n=1,4,8,9$, and ... More
A linear set view on KM-arcsDec 15 2015In this paper, we study KM-arcs of type t, i.e. point sets of size q + t in PG(2, q) such that every line contains 0, 2 or t of its points. We use field reduction to give a different point of view on the class of translation arcs. Starting from a particular ... More
More basic hypergeometric limits of the elliptic hypergeometric beta integralJul 09 2013In this article we continue the work from arXiv:0902.0621. In that article Eric Rains and the present author considered the limits of the elliptic beta integral as p->0 while the parameters t_r have a p-dependence of the form t_r=u_rp^{\alpha_r} (for ... More
Number systems and the Chinese Remainder TheoremJun 21 2011A well-known generalisation of positional numeration systems is the case where the base is the residue class of $x$ modulo a given polynomial $f(x)$ with coefficients in (for example) the integers, and where we try to construct finite expansions for all ... More
High-dimensional generalized linear models and the lassoApr 04 2008We consider high-dimensional generalized linear models with Lipschitz loss functions, and prove a nonasymptotic oracle inequality for the empirical risk minimizer with Lasso penalty. The penalty is based on the coefficients in the linear predictor, after ... More
Fibered Transverse Knots and the Bennequin BoundMar 05 2008Jul 09 2009We prove that a nicely fibered link (by which we mean the binding of an open book) in a tight contact manifold $(M,\xi)$ with zero Giroux torsion has a transverse representative realizing the Bennequin bound if and only if the contact structure it supports ... More
An approximation of Itô diffusions based on simple random walksMar 25 2014The aim of this paper is to develop a sequence of discrete approximations to a one-dimensional It\^o diffusion that almost surely converges to a weak solution of the given stochastic differential equation. Under suitable conditions, the solution of the ... More
Projected Data AssimilationFeb 12 2019We introduce a framework for Data Assimilation (DA) in which the data is split into multiple sets corresponding to low-rank projections of the state space. Algorithms are developed that assimilate some or all of the projected data, including an algorithm ... More
Near Horizon Geometry of Strings Ending on Intersecting D8/D4-branesJul 16 2014We consider solutions of massive IIA supergravity corresponding to the half-BPS intersection of D8/D4-branes with fundamental strings. The $1+1$-dimensional intersection preserves the symmetry $D(2,1;\gamma;1) \times SO(4)$. We give a reduction and partial ... More
The spacetime of a shift automorphismOct 25 2016The automorphism group of a one dimensional shift space over a finite alphabet exhibits different types of behavior: for a large class with positive entropy, it contains a rich collection of subgroups, while for many shifts of zero entropy, there are ... More
Reducing reflections from mesh refinement interfaces in numerical relativityMay 19 2005Full interpretation of data from gravitational wave observations will require accurate numerical simulations of source systems, particularly binary black hole mergers. A leading approach to improving accuracy in numerical relativity simulations of black ... More
Effects of Defects and Dephasing on Charge and Spin Currents in Two-Dimensional Topological InsulatorsSep 06 2016Using the non-equilibrium Keldysh Green's function formalism, we investigate the effect of defects on the electronic structure and transport properties of two-dimensional topological insulators (TI). We demonstrate how the spatial flow of charge changes ... More
The mechanical creep compliance of tissue cells is gamma distributedFeb 05 2010Jul 13 2011Investigations of natural variation among cells within a population are essential for understanding the stochastic nature of tissue cell deformation under applied load. In the existing literature, the population variation of single-cell creep compliance ... More
Monoids in the mapping class groupApr 08 2015In this article we survey, and make a few new observations about, the surprising connection between sub-monoids of mapping class groups and interesting geometry and topology in low-dimensions.
Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas KinematicsMay 19 2014We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest that they contain ... More
On the origin and extent of mechanical variation among cellsApr 04 2011Jun 21 2011Investigations of natural variation in cell mechanics within a cell population are essential to understand the stochastic nature of soft-network deformation. Striking commonalities have been found concerning the average values and distribution of rheological ... More
Controlling the Flow of Spin and Charge in Nanoscopic Topological InsulatorsSep 28 2015Controlling the flow of spin and charge currents in topological insulators (TIs) is a crucial requirement for applications in quantum computation and spin electronics. We demonstrate that such control can be established in nanoscopic two-dimensional TIs ... More
Clustering at 74 MHzAug 28 2009In order to construct accurate point sources simulations at the frequencies relevant to 21 cm experiments, the angular correlation of radio sources must be taken into account. Using the 74 MHz VLSS survey, we measured the angular 2-point correlation function, ... More
Intriguing sets of partial quadranglesDec 15 2008The point-line geometry known as a \textit{partial quadrangle} (introduced by Cameron in 1975) has the property that for every point/line non-incident pair $(P,\ell)$, there is at most one line through $P$ concurrent with $\ell$. So in particular, the ... More
Global General Relativistic Magnetohydrodynamic Simulations of Accretion ToriMar 11 2003This paper presents an initial survey of the properties of accretion flows in the Kerr metric from three-dimensional, general relativistic magnetohydrodynamic simulations of accretion tori. We consider three fiducial models of tori around rotating, both ... More
Electroweak Vacuum Stability and the Seesaw Mechanism RevisitedOct 02 2015Feb 25 2016We study the electroweak vacuum stability in Type I seesaw models for 3 generations of neutrinos in scenarios where the right-handed neutrinos have explicit bare mass terms in the Lagrangian and where these are dynamically generated through the mechanism ... More
Three-Dimensional Hydrodynamic Simulations of Accretion Tori in Kerr SpacetimesApr 09 2002Jun 05 2002This paper presents results of three-dimensional simulations of global hydrodynamic instabilities in black hole tori, extending earlier work by Hawley to Kerr spacetimes. This study probes a three-dimensional parameter space of torus angular momentum, ... More
Physics Motivations for Future CERN AcceleratorsDec 04 2001We summarize the physics motivations for future accelerators at CERN. We argue that (a) a luminosity upgrade for the LHC could provide good physics return for a relatively modest capital investment, (b) CLIC would provide excellent long-term perspectives ... More