Results for "Griffin Foster"

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Theory of excitations of the condensate and non-condensate at finite temperaturesJan 18 1999Jan 20 1999We give an overview of the current theory of collective modes in trapped atomic gases at finite temperatures, when the dynamics of the condensate and non-condensate must both be considered. A simple introduction is given to the quantum field formulation ... More
Conserving and Gapless Approximations for an Inhomogeneous Bose Gas at Finite TemperaturesFeb 07 1996We derive and discuss the equations of motion for the condensate and its fluctuations for a dilute, weakly interacting Bose gas in an external potential within the self--consistent Hartree--Fock--Bogoliubov (HFB) approximation. Account is taken of the ... More
Some hereditarily just infinite subgroups of the Nottingham GroupSep 16 2002This work examines the commutator structure of some closed subgroups of the wild group of automorphisms of a local field with perfect residue field, a group we call $\Cal J.$ In particular, we establish a new approach to evaluating commutators in $\Cal ... More
BEC and the New World of Coherent Matter WavesNov 25 1999This paper is based on three tutorial lectures given at the CRM Summer School in Banff, Alberta, June 27-July 10, 1999 on "Theoretical Physics at the End of the Twentieth Century". They will be published by Springer-Verlag. Lecture I gives a quick overview ... More
Condensate Oscillations, Kinetic Equations and Two-Fluid Hydrodynamics in a Bose GasJun 23 2000This is based on 4 lectures given at the 13th Australian Physics Summer School, Australia National University, Canberra, Jan 17-28, 2000. The main topic is the theory of collective modes in a trapped Bose gas at finite temperatures. A generalized Gross-Pitaevskii ... More
A Brief History of Our Understanding of BEC: From Bose to BeliaevJan 13 1999We review how our current ideas about BEC developed in the early period 1925-1965, which had the specific goal of understanding superfluid $^4$He. This history is presented by commenting on the key contributions made by Einstein, Fritz London, Tisza, ... More
On the Phase-Space Distribution of Bloch Eigenmodes for Periodic Point ScatterersJun 29 2015Jul 26 2016Consider the 3-dimensional Laplacian with a potential described by point scatterers placed on the integer lattice. We prove that for Floquet-Bloch modes with fixed quasi-momentum satisfying a certain Diophantine condition, there is a subsequence of eigenvalues ... More
Operadic comodules and (co)homology theoriesMar 19 2014An operad describes a category of algebras and a (co)homology theory for these algebras may be formulated using the homological algebra of operads. A morphism of operads $f:\mathcal{O}\rightarrow\mathcal{P}$ describes a functor allowing a $\mathcal{P}$-algebra ... More
General tax structures for a Lévy insurance risk process under the Cramér conditionJun 16 2018We investigate the Levy insurance risk model with tax under Cram\'er's condition. A direct analogue of Cram\'er's estimate for the probability of ruin in this model is obtained, together with the asymptotic distribution, conditional on ruin occurring, ... More
Associating curves of low genus to infinite nilpotent groups via the zeta functionSep 20 2002It is known from work of du Sautoy and Grunewald in \cite{duSG1} that the zeta functions counting subgroups of finite index in infinite nilpotent groups depend upon the behaviour of some associated system of algebraic varieties on reduction $\modp.$ Further ... More
Rigorous Density Functional Theory for Inhomogeneous Bose-Condensed FluidsNov 20 1995The density functional theory originally developed by Hohenberg, Kohn and Sham provides a rigorous conceptual framework for dealing with inhomogeneous interacting Fermi systems. We extend this approach to deal with inhomogeneous interacting Bose-condensed ... More
Current and Nascent SETI InstrumentsSep 06 2011Here we describe our ongoing efforts to develop high-performance and sensitive instrumentation for use in the search for extra-terrestrial intelligence (SETI). These efforts include our recently deployed Search for Extraterrestrial Emissions from Nearby ... More
HERA results on the structure of the protonNov 07 2002A selection of results from the H1 and ZEUS experiments at HERA are reviewed, particularly in the area of deep inelastic scattering and diffraction. Quantum chromodynamics gives a good explanation of these data down to surprisingly low values of the four-momentum ... More
Visions of ep physicsJun 04 2002The subject of lepton-hadron scattering is discussed from its earliest beginnings, concentrating on what we have learnt from the HERA electron-proton storage ring. A brief selection of the HERA I results most relevant to LHC are discussed. The HERA and ... More
Zeus at HERA IIJul 24 2001The ZEUS detector has been upgraded in a number of areas to prepare for the physics opportunities of HERA II. These upgrades, and their physics rationale and promise, are briefly outlined. The measurement of polarisation at HERA II, and its importance ... More
Galois actions on analytifications and tropicalizationsMar 22 2017Mar 30 2017This paper initiates a research program that seeks to recover algebro-geometric Galois representations from combinatorial data. We study tropicalizations equipped with symmetries coming from the Galois-action present on the lattice of $1$-parameter subgroups ... More
Low-x PhysicsAug 28 2000Low-x physics is reviewed, with particular emphasis on searches for deviations from GLAP evolution of the parton densities. Although there are several intriguing indications, both in HERA and Tevatron data, as yet there is no unambiguous evidence for ... More
Higher configuration operads by way of quiver GrassmanniansNov 19 2012We introduce a construction that associates, to each finite dimensional k-vector space V, a family of projective k-varieties that comes equipped with the structure of a operad in the category of k-schemes. When dim V = 1, this operad contains, as a suboperad, ... More
Static Hopfion solutions of the extended Skyrme-Faddeev modelOct 02 2012We construct non-axially symmetric static soliton solutions, with non-zero topological charges, of an extension of the Skyrme-Faddeev model. The model has an extra quartic-derivative term and we choose its coupling to the Skyrme-term to be negative. We ... More
Deep Inelastic Scattering at HERADec 23 1997Results from the H1 and ZEUS experiments at HERA on deep inelastic scattering are reviewed. The data lead to a consistent picture of a steep rise in the F_2 structure function and in the gluon density within the proton. Important new information on the ... More
High Precision Arithmetic for Scientific ApplicationsSep 21 2013All but a few digital computers used for scientific computations have supported floating-point and digital arithmetic of rather limited numerical precision. The underlying assumptions were that the systems being studied were basically deterministic and ... More
A Noncommutative Version of the Natural NumbersMar 10 2010In this note, we construct and study an algebraic system similar to the natural numbers, but with noncommutative addition. The addition we introduce is a binary operation that commutes with itself in the sense of N. Durov. Neverheless, the multiplication ... More
HT90 and "simplest" number fieldsJul 25 2012A standard formula (1) leads to a proof of HT90, but requires proving the existence of $\theta$ such that $\alpha\ne 0$, so that $\beta=\alpha/\sigma(\alpha)$. We instead impose the condition (M), that taking $\theta=1$ makes $\alpha=0$. Taking $n=3$, ... More
Human-Machine Symbiosis, 50 Years OnDec 13 2007Licklider advocated in 1960 the construction of computers capable of working symbiotically with humans to address problems not easily addressed by humans working alone. Since that time, many of the advances that he envisioned have been achieved, yet the ... More
Neutrino Factory R&D - a global perspectiveNov 15 2002The current world status of plans for future particle-physics accelerators and accelerator research and development is outlined. The developments for a neutrino factory are placed in this context. Finally, a specific initiative relevant for Europe is ... More
Lectures on HERA physicsJun 05 2002In these lectures I introduce the basics of HERA physics and give a survey of the major aspects, discussing in somewhat more depth the subject of low $x$ physics.
The decay of Hopf solitons in the Skyrme modelOct 05 2016It is understood that the Skyrme model has a topologically interesting baryonic excitation which can model nuclei. So far no stable knotted solutions, of the Skyrme model, have been found. Here we investigate the dynamics of Hopf solitons decaying to ... More
Massive HopfionsDec 12 2010The Skyrme-Faddeev model is a (3+1)-dimensional model which has knotted, string-like, soliton solutions. In this paper we investigate a Skyrme-Faddeev model with an SO(3) symmetry breaking potential. We then rescale this model and take the mass to infinity. ... More
Classifying the near-equality of ribbon Schur functionsOct 01 2018We consider the problem of determining when the difference of two ribbon Schur functions is a single Schur function. We prove that this near-equality phenomenon occurs in sixteen infinite families and we conjecture that these are the only possible cases. ... More
An adaptive truncation method for inference in Bayesian nonparametric modelsAug 09 2013May 21 2014Many exact Markov chain Monte Carlo algorithms have been developed for posterior inference in Bayesian nonparametric models which involve infinite-dimensional priors. However, these methods are not generic and special methodology must be developed for ... More
Modelling and computation using NCoRM mixtures for density regressionAug 02 2016Aug 03 2016Normalized compound random measures are flexible nonparametric priors for related distributions. We consider building general nonparametric regression models using normalized compound random measure mixture models. We develop a general approach to the ... More
Convolution equivalent Lévy processes and first passage timesMay 22 2012Jul 22 2013We investigate the behavior of L\'{e}vy processes with convolution equivalent L\'{e}vy measures, up to the time of first passage over a high level u. Such problems arise naturally in the context of insurance risk where u is the initial reserve. We obtain ... More
Fermi excitations in a trapped atomic Fermi gas with a molecular Bose condensateFeb 02 2004Feb 10 2004We discuss the effect of a molecular Bose condensate on the energy of Fermi excitations in a trapped two-component atomic Fermi gas. The single-particle Green's functions can be approximated by the well-known BCS form, in both the BCS (Cooper pairs) and ... More
Superfluidity and collective modes in a uniform gas of Fermi atoms with a Feshbach resonanceFeb 11 2003We investigate strong-coupling superfluidity in a uniform gas of Fermi atoms attractively interacting via quasi-molecular bosons associated with a Feshbach resonance. This interaction is tunable by the threshold energy $2\nu$ of the Feshbach resonance, ... More
Landau-Khalatnikov two-fluid hydrodynamics of a trapped Bose gasSep 21 2000Starting from the quantum kinetic equation for the non-condensate atoms and the generalized Gross-Pitaevskii equation for the condensate, we derive the two-fluid hydrodynamic equations of a trapped Bose gas at finite temperatures. We follow the standard ... More
Single-particle excitations in a trapped gas of Fermi atoms in the BCS-BEC crossover regionOct 08 2004We investigate the single-particle properties at T=0 of a trapped superfluid gas of Fermi atoms with a Feshbach resonance. A tunable pairing interaction associated with the Feshbach resonance leads to the BCS-BEC crossover, where the character of superfluidity ... More
Hydrodynamic modes and pulse propagation in a cylindrical Bose gas above the Bose-Einstein transitionJun 09 1998We study hydrodynamic oscillations of a cylindrical Bose gas above the Bose-Einstein transition temperature using the hydrodynamic equations derived by Griffin, Wu and Stringari. This extends recent studies of a cylindrical Bose-condensed gas at T=0. ... More
Surface Region of Superfluid Helium as an Inhomogeneous Bose-Condensed GasNov 20 1995We present arguments that the low density surface region of self-bounded superfluid $^4$He systems is an inhomogeneous dilute Bose gas, with almost all of the atoms occupying the same single-particle state at $T = 0$. Numerical evidence for this complete ... More
Optimal Control Model of Software Quality for Digital VendorsDec 30 2014This paper models a firm's level of effort in mobile software application production as an optimal control problem to maximize market share and profit in a digital marketplace. Through a rumor-spreading system dynamic, a digital goods vendor can capture ... More
The sine-Gordon model and the small k^+ region of light-cone perturbation theoryJul 24 1992The non-perturbative ultraviolet divergence of the sine-Gordon model is used to study the $k^+ = 0$ region of light-cone perturbation theory. The light-cone vacuum is shown to be unstable at the non-perturbative $\beta^2 = 8\pi$ critical point by a light-cone ... More
Solving 3+1 QCD on the Transverse Lattice Using 1+1 Conformal Field TheoryAug 20 1991A new transverse lattice model of $3+1$ Yang-Mills theory is constructed by introducing Wess-Zumino terms into the 2-D unitary non-linear sigma model action for link fields on a 2-D lattice. The Wess-Zumino terms permit one to solve the basic non-linear ... More
Light Front Hamiltonian for Transverse Lattice QCDNov 01 1994A calculational framework for determining masses of low lying hadrons using light front quantization is discussed. The method is based upon four theoretical tools: discrete light cone quantization, which has been very successful in 1+1 dimensional models, ... More
A Boundary Tilting Persepective on the Phenomenon of Adversarial ExamplesAug 27 2016Deep neural networks have been shown to suffer from a surprising weakness: their classification outputs can be changed by small, non-random perturbations of their inputs. This adversarial example phenomenon has been explained as originating from deep ... More
The APEX/EPOS Quandary: the Way Out via Low Energy StudiesFeb 16 1998Feb 17 1998A scorecard summary of the various data of the ``Sharp Lepton Problem'' is presented. The present situation, in which APEX reports ``...no evidence for sharp pairs...'' even as their data exhibits a sharp pair excess near 800 keV, is discussed. Two kinds ... More
Comment on "A Search for Narrow Sum Energy Lines in Electron-Positron Pair Emission from Heavy Ion collisions near the Coulomb Barrier"Mar 18 1997The report of Ahmad et al., states that ``No evidence is found for sharp peaks in the present data.'' But this statement is factually inaccurate. Figure 1 exhibits the APEX' published U + Th ``wedge cut'' data, and background, which show a distinct (3.2 ... More
Genuine onion: Simple, Fast, Flexible, and Cheap Website AuthenticationJun 12 2015Tor is a communications infrastructure widely used for unfettered and anonymous access to Internet websites. Tor is also used to access sites on the .onion virtual domain. The focus of .onion use and discussion has traditionally been on the offering of ... More
Cacti and filtered distributive lawsSep 25 2011Motivated by the second author's construction of a classifying space for the group of pure symmetric automorphisms of a free product, we introduce and study a family of topological operads, the operads of based cacti, defined for every pointed topological ... More
The obstacle problem for subelliptic non-divergence form operators on homogeneous groupsJul 16 2013The main result established in this paper is the existence and uniqueness of strong solutions to the obstacle problem for a class of subelliptic operators in non-divergence form. The operators considered are structured on a set of smooth vector fields ... More
Intrinsic Instrumental Polarization and High-Precision Pulsar TimingJul 24 2015Radio telescopes are used to accurately measure the time of arrival (ToA) of radio pulses in pulsar timing experiments that target mostly millisecond pulsars (MSPs) due to their high rotational stability. This allows for detailed study of MSPs and forms ... More
Fast Radio Burst 121102 Pulse Detection and Periodicity: A Machine Learning ApproachSep 09 2018We report the detection of 72 new pulses from the repeating fast radio burst FRB 121102 in Breakthrough Listen C-band (4-8 GHz) observations at the Green Bank Telescope. The new pulses were found with a convolutional neural network in data taken on August ... More
Single-particle excitations in the BCS-BEC crossover region II: Broad Feshbach resonanceAug 09 2005We apply the formulation developed in a recent paper [Y. Ohashi and A. Griffin, Phys. Rev. A {\bf 72}, 013601, (2005)] for single-particle excitations in the BCS-BEC crossover to the case of a broad Feshbach resonance. At T=0, we solve the Bogoliubov-de ... More
Landau damping of Bogoliubov excitations in optical lattices at finite temperatureJun 01 2005We study the damping of Bogoliubov excitations in an optical lattice at finite temperatures. For simplicity, we consider a Bose-Hubbard tight-binding model and limit our analysis to the lowest excitation band. We use the Popov approximation to calculate ... More
Damping of Bogoliubov Excitations in Optical LatticesNov 13 2003Extending recent work to finite temperatures, we calculate the Landau damping of a Bogoliubov excitation in an optical lattice, due to coupling to a thermal cloud of such excitations. For simplicity, we consider a 1D Bose-Hubbard model and restrict ourselves ... More
Hydrodynamic damping in trapped Bose gasesNov 05 1997Jan 06 1998Griffin, Wu and Stringari have derived the hydrodynamic equations of a trapped dilute Bose gas above the Bose-Einstein transition temperature. We give the extension which includes hydrodynamic damping, following the classic work of Uehling and Uhlenbeck ... More
The Surface Region of Superfluid $^4$He as a Dilute Bose-Condensed GasJun 10 1996In the low-density surface region of superfluid $^4$He, the atoms are far apart and collisions can be ignored. The only effect of the interactions is from the long-range attractive Hartree potential produced by the distant high-density bulk liquid. As ... More
Non linear difference equations arising from a deformation of the q-Laguerre weightApr 11 2014We study, in this paper, a one parameter deformation of the $q-$Laguerre weight function. An investigation is made on the polynomials orthogonal with respect to such a weight. With the aid of the two compatibility conditions previously obtained in \cite{Chen-Ism} ... More
Sample path behavior of a Lévy insurance risk process approaching ruin, under the Cramér-Lundberg and convolution equivalent conditionsSep 26 2013Jan 07 2016Recent studies have demonstrated an interesting connection between the asymptotic behavior at ruin of a L\'evy insurance risk process under the Cram\'er-Lundberg and convolution equivalent conditions. For example, the limiting distributions of the overshoot ... More
Staggered fermions and chiral symmetry breaking in transverse lattice regulated QEDJul 24 1992Staggered fermions are constructed for the transverse lattice regularization scheme. The weak perturbation theory of transverse lattice non-compact QED is developed in light-cone gauge, and we argue that for fixed lattice spacing this theory is ultraviolet ... More
Limit theorems for skew translationsJul 16 2014Bufetov, Bufetov-Forni and Bufetov-Solomyak have recently proved limit theorems for translation flows, horocycle flows and tiling flows, respectively. We present here analogous results for skew translations of a torus.
The Fesenko groups have finite widthOct 03 2003We prove that the Fesenko Groups, which occur as natural closed subgroups of the Nottingham Group, have finite width and infinite obliquity.
Implementation of a Direct-Imaging and FX Correlator for the BEST-2 ArrayJan 27 2014A new digital backend has been developed for the BEST-2 array at Radiotelescopi di Medicina, INAF-IRA, Italy which allows concurrent operation of an FX correlator, and a direct-imaging correlator and beamformer. This backend serves as a platform for testing ... More
A Problem-Specific Fault-Tolerance Mechanism for Asynchronous, Distributed SystemsMar 12 2000The idle computers on a local area, campus area, or even wide area network represent a significant computational resource---one that is, however, also unreliable, heterogeneous, and opportunistic. This type of resource has been used effectively for embarrassingly ... More
Strong field effects on binary systems in Einstein-aether theoryJun 05 2007Sep 23 2008"Einstein-aether" theory is a generally covariant theory of gravity containing a dynamical preferred frame. This article continues an examination of effects on the motion of binary pulsar systems in this theory, by incorporating effects due to strong ... More
Degenerations of toric varieties over valuation ringsAug 17 2015Jul 02 2016We develop a theory of multi-stage degenerations of toric varieties over finite rank valuation rings, extending the Mumford--Gubler theory in rank one. Such degenerations are constructed from fan-like structures over totally ordered abelian groups of ... More
Universality of collapsing two-dimensional self-avoiding trailsJul 15 2009Aug 13 2009Results of a numerically exact transfer matrix calculation for the model of Interacting Self-Avoiding Trails are presented. The results lead to the conclusion that, at the collapse transition, Self-Avoiding Trails are in the same universality class as ... More
Scattering of SkyrmionsDec 30 2014Jun 30 2015In this paper, we present a detailed study of Skyrmion-Skyrmion scattering for two $B=1$ Skyrmions in the attractive channel where we observe two different scattering regimes. For large separation, the scattering can be approximated as interacting dipoles. ... More
The Mass Spectrum of a Static Adjoint ParticleSep 16 1997The bound states of fermions in the adjoint representation are of interest in supersymmetric models. We investigate the energy spectrum of the simplest -- the gluino-gluon bound states -- on several lattices in the quenched approximation. We use a static ... More
Semisimplicity of certain representation categoriesSep 04 2015We exhibit a correspondence between subcategories of modules over an algebra and sub-bimodules of the dual of that algebra. We then prove that the semisimplicity of certain such categories is equivalent to the existence of a Peter-Weyl decomposition of ... More
Applications of Data Mining to Electronic CommerceOct 02 2000Electronic commerce is emerging as the killer domain for data mining technology. The following are five desiderata for success. Seldom are they they all present in one data mining application. 1. Data with rich descriptions. For example, wide customer ... More
Mission Opportunities for Human Exploration of Nearby Planetary BodiesOct 18 2016We characterize mission profiles for human expeditions to near-Earth asteroids, Venus, and Mars. Near-Earth objects (NEOs) are the closest destinations beyond cis-lunar space and present a compelling target with capabilities already under development ... More
Classical-physics applications for Finsler $b$ spaceApr 23 2015The classical propagation of certain Lorentz-violating fermions is known to be governed by geodesics of a four-dimensional pseudo-Finsler $b$ space parametrized by a prescribed background covector field. This work identifies systems in classical physics ... More
Usage Policy-based CPU Sharing in VOsNov 12 2004Resource sharing within Grid collaborations usually implies specific sharing mechanisms at participating sites. Challenging policy issues can arise within virtual organizations (VOs) that integrate participants and resources spanning multiple physical ... More
Noether charges and black hole mechanics in Einstein-aether theorySep 29 2005Dec 09 2005The Noether charge method for defining the Hamiltonian of a diffeomorphism-invariant field theory is applied to "Einstein-aether" theory, in which gravity couples to a dynamical, timelike, unit-norm vector field. Using the method, expressions are obtained ... More
Multifractal nature of the surface local density of states in three-dimensional topological insulators with magnetic and nonmagnetic disorderNov 28 2011Feb 22 2012We compute the multifractal spectra associated to local density of states (LDOS) fluctuations due to weak quenched disorder, for a single Dirac fermion in two spatial dimensions. Our results are relevant to the surfaces of Z_2 topological insulators such ... More
Primes in short intervals on curves over finite fieldsJan 24 2017Mar 31 2018We prove an analogue of the Prime Number Theorem for short intervals on a smooth projective geometrically irreducible curve of arbitrary genus over a finite field. A short interval "of size E" in this setting is any additive translate of the space of ... More
Radiation Damping in Einstein-Aether TheoryFeb 01 2006Sep 23 2008This work concerns the loss of energy of a material system due to gravitational radiation in Einstein-aether theory-an alternative theory of gravity in which the metric couples to a dynamical, timelike, unit-norm vector field. Derived to lowest post-Newtonian ... More
Metric Redefinitions in Einstein-Aether TheoryFeb 14 2005Aug 01 2005`Einstein-Aether' theory, in which gravity couples to a dynamical, time-like, unit-norm vector field, provides a means for studying Lorentz violation in a generally covariant setting. Demonstrated here is the effect of a redefinition of the metric and ... More
Physics of Low-Dimensional Ultracold Bose GasesFeb 03 2013In this work we investigate the unique properties of ultracold Bose gases in one and two dimensions. In two dimensions, we present simulations of the Berezinskii-Kosterlitz-Thouless (BKT) phase transition using the projected Gross-Pitaevskii equation ... More
Negative Baryon density and the Folding structure of the B=3 SkyrmionJan 17 2013The Skyrme model is a non-linear field theory whose solitonic solutions, once quantised, describe atomic nuclei. The classical static soliton solutions, so-called Skyrmions, have interesting discrete symmetries and can only be calculated numerically. ... More
Surface critical behaviour of the Interacting Self-Avoiding Trail on the square latticeJul 01 2010The surface critical behaviour of the interacting self-avoiding trail is examined using transfer matrix methods coupled with finite-size scaling. Particular attention is paid to the critical exponents at the ordinary and special points along the collapse ... More
Any-gram Kernels for Sentence Classification: A Sentiment Analysis Case StudyDec 19 2017Any-gram kernels are a flexible and efficient way to employ bag-of-n-gram features when learning from textual data. They are also compatible with the use of word embeddings so that word similarities can be accounted for. While the original any-gram kernels ... More
Better Image Segmentation by Exploiting Dense Semantic PredictionsJun 05 2016It is well accepted that image segmentation can benefit from utilizing multilevel cues. The paper focuses on utilizing the FCNN-based dense semantic predictions in the bottom-up image segmentation, arguing to take semantic cues into account from the very ... More
Coupled Hartree-Fock-Bogoliubov kinetic equations for a trapped Bose gasDec 16 1998Using the Kadanoff-Baym non-equilibrium Green's function formalism, we derive the self-consistent Hartree-Fock-Bogoliubov (HFB) collisionless kinetic equations and the associated equation of motion for the condensate wavefunction for a trapped Bose-condensed ... More
Lasso ANOVA Decompositions for Matrix and Tensor DataMar 24 2017Feb 09 2019Consider the problem of estimating the entries of an unknown mean matrix or tensor given a single noisy realization. In the matrix case, this problem can be addressed by decomposing the mean matrix into a component that is additive in the rows and columns, ... More
Structured Shrinkage PriorsFeb 13 2019Feb 15 2019In many regression settings the unknown coefficients may have some known structure, for instance they may be ordered in space or correspond to a vectorized matrix or tensor. At the same time, the unknown coefficients may be sparse, with many nearly or ... More
Spin lattices with two-body Hamiltonians for which the ground state encodes a cluster stateMay 19 2008Jan 05 2009We present a general procedure for constructing lattices of qubits with a Hamiltonian composed of nearest-neighbour two-body interactions such that the ground state encodes a cluster state. We give specific details for lattices in one-, two-, and three-dimensions, ... More
Dynamic correlation functions in one-dimensional quasi-condensatesDec 04 2002We calculate the static and dynamic single-particle correlation functions in one-dimensional (1D) trapped Bose gases and discuss experimental measurements that can directly probe such correlation functions. Using a quantized hydrodynamic theory for the ... More
Damped Bogoliubov excitations of a condensate interacting with a static thermal cloudSep 01 2000Oct 25 2000We calculate the damping of condensate collective excitations at finite temperatures arising from the lack of equilibrium between the condensate and thermal atoms. We neglect the non-condensate dynamics by fixing the thermal cloud in static equilibrium. ... More
Damping of condensate collective modes due to equilibration with the non-condensateMar 29 2000Oct 04 2000We consider the damping of condensate collective modes at finite temperatures arising from lack of equilibrium between the condensate and the non-condensate atoms, an effect that is ignored in the usual discussion of the collisionless region. As a first ... More
Quantized hydrodynamic model and the dynamic structure factor for a trapped Bose gasJun 11 1996We quantize the recent hydrodynamic analysis of Stringari for the low-energy collective modes of a trapped Bose gas at $T=0$. This is based on the time-dependent Gross-Pitaevskii equation, but omits the kinetic energy of the density fluctuations. We diagonalize ... More
Compound random measures and their use in Bayesian nonparametricsOct 02 2014Sep 02 2015A new class of dependent random measures which we call {\it compound random measures} are proposed and the use of normalized versions of these random measures as priors in Bayesian nonparametric mixture models is considered. Their tractability allows ... More
Verifying and Reporting Fast Radio BurstsAug 23 2018Fast Radio Bursts (FRBs) are a class of short-duration transients at radio wavelengths with inferred astrophysical origin. The prototypical FRB is a broadband signal that occurs over the extent of the receiver frequency range, is narrow in time, and is ... More
Structured Shrinkage PriorsFeb 13 2019In many regression settings the unknown coefficients may have some known structure, for instance they may be ordered in space or correspond to a vectorized matrix or tensor. At the same time, the unknown coefficients may be sparse, with many nearly or ... More
Surface Contribution to Raman Scattering from Layered SuperconductorsMar 01 1996Generalizing recent work, the Raman scattering intensity from a semi-infinite superconducting superlattice is calculated taking into account the surface contribution to the density response functions. Our work makes use of the formalism of Jain and Allen ... More
Optimal Weighting of Multi-View Data with Low Dimensional Hidden StatesSep 25 2012Sep 26 2012In Natural Language Processing (NLP) tasks, data often has the following two properties: First, data can be chopped into multi-views which has been successfully used for dimension reduction purposes. For example, in topic classification, every paper can ... More
The statistical mechanics of the two-dimensional hydrogen-bonding self-avoiding walk including solvent effectsOct 28 2007A two-dimensional square-lattice model for the formation of secondary structures in proteins, the hydrogen-bonding model, is extended to include the effects of solvent quality. This is achieved by allowing configuration-dependent nearest-neighbour interactions. ... More
Large scale canonical correlation analysis with iterative least squaresJul 16 2014Dec 30 2014Canonical Correlation Analysis (CCA) is a widely used statistical tool with both well established theory and favorable performance for a wide range of machine learning problems. However, computing CCA for huge datasets can be very slow since it involves ... More
Fast Ridge Regression with Randomized Principal Component Analysis and Gradient DescentMay 15 2014We propose a new two stage algorithm LING for large scale regression problems. LING has the same risk as the well known Ridge Regression under the fixed design setting and can be computed much faster. Our experiments have shown that LING performs well ... More
Drinfeld Orbifold Algebras for Symmetric GroupsNov 01 2016Drinfeld orbifold algebras are a type of deformation of skew group algebras generalizing graded Hecke algebras of interest in representation theory, algebraic combinatorics, and noncommutative geometry. In this article, we classify all Drinfeld orbifold ... More
The Size, Shape and Orientation of Cosmological Voids in the Sloan Digital Sky SurveyApr 30 2009Jun 23 2009We present a detailed description of our void finding algorithm which is an extension of the prescription by Hoyle and Vogeley (2002). We include a discussion of the reproducibility and robustness of the algorithm as well as the statistical significance ... More