Results for "Morgan Trassin"

total 1362took 0.11s
A dynamical magnetic field accompanying the motion of ferroelectric domain wallsApr 12 2019The recently proposed dynamical multiferroic effect describes the generation of magnetization from temporally varying electric polarization. Here, we show that the effect can lead to a magnetic field at moving ferroelectric domain walls, where the rearrangement ... More
Magnetic properties and domain structure of ultrathin yttrium iron garnet/Pt bilayersMar 19 2019We report on the structure, magnetization, magnetic anisotropy, and domain morphology of ultrathin yttrium iron garnet (YIG)/Pt films with thickness ranging from 3 to 90 nm. We find that the saturation magnetization is close to the bulk value in the thickest ... More
Domain wall architecture in tetragonal ferroelectric thin filmsFeb 22 2017Domain walls in ferroelectrics exhibit a plethora of phases and functionalities not found in the bulk. The interplay of electrostatic, chemical, topological, and distortive inhomogeneities at the walls can be so complex, however, that this obstructs their ... More
Magnetoresistance of heavy and light metal/ferromagnet bilayersOct 21 2015We studied the magnetoresistance of normal metal (NM)/ferromagnet (FM) bilayers in the linear and nonlinear (current-dependent) regimes and compared it with the amplitude of the spin-orbit torques and thermally induced electric fields. Our experiments ... More
Overview of Deeply Virtual Compton Scattering at HERMESJun 14 2012Deeply Virtual Compton Scattering represents the best experimental channel through which to understand Generalised Parton Distributions. The HERMES experiment measured the most diverse set of DVCS results of any experiment; this talk discusses the most ... More
Unary Classical MechanicsJan 02 2019Classical mechanics is presented here in a unary operator form, constructed using the binary multiplication and Poisson bracket operations that are given in a phase space formalism, then a Gibbs equilibrium state over this unary operator algebra is introduced, ... More
In orbifolds, small isoperimetric regions are small ballsDec 23 2006Jun 28 2008In a compact orbifold, for small prescribed volume, an isoperimetric region is close to a small metric ball; in a Euclidean orbifold, it is a small metric ball.
Regularity of area-minimizing surfaces in 3D polytopes and of invariant hypersurfaces in R^nApr 27 2004In (the surface of) a convex polytope P^3 in R^4, an area-minimizing surface avoids the vertices of P and crosses the edges orthogonally. In a smooth Riemannian manifold M with a group of isometries G, an area-minimizing G-invariant oriented hypersurface ... More
Classical states, quantum field measurementSep 20 2017Mar 06 2019Classical Koopman--von Neumann Hilbert spaces of states are constructed here by the action of classical random fields on a vacuum state in ways that support an action of the quantized electromagnetic field and of the $U(1)$--invariant observables of the ... More
A graphical presentation of signal delays in the datasets of Weihs et alJul 24 2012A graphical presentation of the timing of avalanche photodiode events in the datasets from the experiment of Weihs et al. [Phys. Rev. Lett. 81, 5039 (1998)] makes manifest the existence of two types of signal delay: (1) The introduction of rapid switching ... More
Lie fields revisitedApr 25 2007Nov 27 2007A class of interacting classical random fields is constructed using deformed *-algebras of creation and annihilation operators. The fields constructed are classical random field versions of "Lie fields". A vacuum vector is used to construct linear forms ... More
A relativistic variant of the Wigner functionApr 28 2003Dec 17 2003The conventional Wigner function is inappropriate in a quantum field theory setting because, as a quasiprobability density over phase space, it is not manifestly Lorentz covariant. A manifestly relativistic variant is constructed as a quasiprobability ... More
Models of measurement for quantum fields and for classical continuous random fieldsJul 24 2006A quantum field model for an experiment describes thermal fluctuations explicitly and quantum fluctuations implicitly, whereas a comparable continuous random field model would describe both thermal and quantum fluctuations explicitly. An ideal classical ... More
Bell inequalities for random fieldsMar 29 2004May 24 2006The assumptions required for the derivation of Bell inequalities are not usually satisfied for random fields in which there are any thermal or quantum fluctuations, in contrast to the general satisfaction of the assumptions for classical two point particle ... More
Bell inequalities and incompatible measurementsJul 17 2003Bell inequalities are a consequence of measurement incompatibility (not, as generally thought, of nonlocality). In classical terms, this is equivalent to contextuality -- measurement devices do have a significant effect. Contextual models are reasonable ... More
A classical perspective on nonlocality in quantum field theoryJun 25 2001Nov 07 2001A classical statistical field theory hidden variable model for the quantized Klein-Gordon model is constructed that preserves relativistic signal locality and is relativistically covariant, but is at the same time relativistically nonlocal, paralleling ... More
Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strainSep 20 2016A current challenge studying magnetically-driven multiferroics is to identify systems that allow a targeted tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state in a thin film of the archetypal ... More
DVCS at HERMESJan 08 2013Jan 11 2013This talk explores the impact that the Hermes experiment has had regarding knowledge of the Deeply Virtual Compton Scattering process. We discuss the various measurements that Hermes has contributed to the library of DVCS knowledge, with focus in particular ... More
Extremal divisors on moduli spaces of rational curves with marked pointsSep 27 2013Apr 28 2016We study effective divisors on $\overline{M}_{0,n}$, focusing on hypertree divisors introduced by Castravet and Tevelev and the proper transforms of divisors on $\overline{M}_{1,n-2}$ introduced by Chen and Coskun. Results include a database of hypertree ... More
Nonlinear Wightman fieldsNov 12 2012Dec 06 2012A nonlinear Wightman field is taken to be a nonlinear map from a linear space of test functions to a linear space of Hilbert space operators, with inessential modifications to other axioms only to the extent dictated by the introduction of nonlinearity. ... More
Embedding quantum and random optics in a larger field theoryJun 09 2008Introducing creation and annihilation operators for negative frequency components extends the algebra of smeared local observables of quantum optics to include an associated classical random field optics.
Nonlinear dependence of the renormalization scale on test functionsSep 19 2013Quantum electrodynamics exhibits an informal nonlinear dependence on Lorentz invariant test function properties that determine the renormalization scale, such as Mandelstam variables, contrary to the linear dependence on test functions that is required ... More
Equivalence of the Klein-Gordon random field and the complex Klein-Gordon quantum fieldMay 08 2009Aug 29 2009The difference between a Klein-Gordon random field and the complex Klein-Gordon quantum field is characterized, explicitly comparing the roles played by negative frequency modes of test functions in creation and annihilation operator presentations of ... More
Weakened linearity for quantum fieldsDec 22 2005Oct 10 2006There are still no interacting models of the Wightman axioms, suggesting that the axioms are too tightly drawn. Here a weakening of linearity for quantum fields is proposed, with the algebra still linear but with the quantum fields no longer required ... More
Hexagonal surfaces of KapouleasMay 07 2004For the "hexagonal" norm on R^3, for which the isoperimetric shape is a hexagonal prism rather than a round ball, we give analogs of the compact immersed constant-mean-curvature surfaces of Kapouleas.
Mitchell-style forcing, with small working parts and collections of models as side conditions, and gap-one simplified morassesNov 22 2014We give a modification of Mitchell's technique for adding objects of size $\omega_2$ with conditions with finite working parts in which the collections of models used as side conditions are very highly structured, arguably making them more wieldy. We ... More
Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strainSep 20 2016Oct 31 2016A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic ... More
Re-encoding reformulation and application to Welch-Berlekamp algorithmDec 21 2012Jul 11 2014The main decoding algorithms for Reed-Solomon codes are based on a bivariate interpolation step, which is expensive in time complexity. Lot of interpolation methods were proposed in order to decrease the complexity of this procedure, but they stay still ... More
New Set of Codes for the Maximum-Likelihood Decoding ProblemNov 12 2010The maximum-likelihood decoding problem is known to be NP-hard for general linear and Reed-Solomon codes. In this paper, we introduce the notion of A-covered codes, that is, codes that can be decoded through a polynomial time algorithm A whose decoding ... More
Cuntz-Pimsner Algebras and Twisted Tensor ProductsJan 28 2016Given two correspondences $X$ and $Y$ and a discrete group $G$ which acts on $X$ and coacts on $Y$, one can define a twisted tensor product $X\boxtimes Y$ which simultaneously generalizes ordinary tensor products and crossed products by group actions ... More
Cuntz-Pimsner Algebras Associated to Tensor Products of CorrespondencesOct 16 2015Given two correspondences X and Y, we show that (under mild hypotheses) the Cuntz-Pimsner algebra of the tensor product of X and Y embeds as a certain subalgebra of the tensor product of the Cuntz-Pimsner algebra of X and the Cuntz=Pimsner algebra of ... More
Quantum Hamiltonian reduction of W-algebras and category OOct 26 2015We define a quantum version of Hamiltonian reduction by stages, producing a construction in type A for a quantum Hamiltonian reduction from the W-algebra $U(\mathfrak{g},e_1)$ to an algebra conjecturally isomorphic to $U(\mathfrak{g},e_2)$, whenever $e_2 ... More
Quantum Hamiltonian reduction of W-algebras and category OFeb 25 2015W-algebras are a class of non-commutative algebras related to the classical universal enveloping algebras. They can be defined as a subquotient of U(g) related to a choice of nilpotent element e and compatible nilpotent subalgebra m. The definition is ... More
On an extension of Galligo's theorem concerning the Borel-fixed points on the Hilbert schemeDec 01 2005Given an ideal $I$ and a weight vector $w$ which partially orders monomials we can consider the initial ideal $\init_w (I)$ which has the same Hilbert function. A well known construction carries this out via a one-parameter subgroup of a $\GL_{n+1}$ which ... More
Multi-particle quantum fields for bound states and interactionsJul 29 2015Mar 01 2017The Fock-Hilbert space generated by a single-particle interaction-free Wightman field is augmented by introducing non-trivial multi-particle (that is, multi-point, multilinear) quantum fields, which is justified insofar as Haag's theorem establishes that ... More
The Space of Planar Soap Bubble ClustersMay 24 2016Soap bubbles and foams have been extensively studied by scientists, engineers, and mathematicians as models for organisms and materials, with applications ranging from extinguishing fires to mining to baking bread. Here we provide some basic results on ... More
Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strainSep 20 2016Mar 25 2017A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic ... More
High-speed domain wall racetracks in a magnetic insulatorFeb 14 2019Recent reports of current-induced switching of ferrimagnetic oxides coupled to a heavy metal layer have opened realistic prospects for implementing magnetic insulators into electrically addressable spintronic devices. However, key aspects such as the ... More
Dvcs @ HermesJan 08 2013The study of Generalised Parton Distributions (GPDs) promises to provide new knowl- edge of the structure of the nucleon, including, most notably, access to the total angular momentum of quarks within the nucleon. It can be difficult to ascertain new ... More
Interest Point Detection for Reconstruction in High Granularity Tracking DetectorsJun 15 2010This paper presents an investigation of the use of interest point detection algorithms from image processing applied to reconstruction of interactions in high granularity tracking detectors. Their purpose is to extract keypoints from the data as input ... More
A local version of Gotzmann's PersistenceOct 01 2007Gotzmann's Persistence states that the growth of an arbitrary ideal can be controlled by comparing it to the growth of the lexicographic ideal. This is used, for instance, in finding equations which cut out the Hilbert scheme (of subschemes of $\mathbf{P}^n$ ... More
2-Selmer Parity for Hyperelliptic Curves in Quadratic ExtensionsApr 08 2015We study the 2-parity conjecture for Jacobians of hyperelliptic curves over number fields. Under some mild assumptions on their reduction, we prove it over quadratic extensions of the base field, providing essentially the first examples of the 2-parity ... More
Issues in Light Hadron SpectroscopyNov 02 1993A high priority in light spectroscopy is to seek out and characterize various types of non-$(Q\bar{Q}$) meson. The large quantity of new data now appearing will present a great opportunity. To identify the non-$(Q\bar{Q}$) intruders one needs to know ... More
Regularization by Test FunctionJun 22 2014Quantum fields are generally taken to be operator-valued distributions, linear functionals of test functions into an algebra of operators; here the effective dynamics of an interacting quantum field is taken to be nonlinearly modified by properties of ... More
A succinct presentation of the quantized Klein-Gordon field, and a similar quantum presentation of the classical Klein-Gordon random fieldNov 21 2004Mar 22 2005A succinct presentation of the algebraic structure of the quantized Klein-Gordon field can be given in terms of a Lorentz invariant inner product. A presentation of a classical Klein-Gordon \emph{random} field at non-zero temperature can be given in the ... More
A geometry for the electroweak fieldFeb 07 2003The structure of the electroweak theory is suggested by classical geometrical ideas. A nonlinear map is constructed, from a 12-dimensional linear space of three Weyl spinors onto the 12-dimensional tangent bundle of the Stiefel manifold of orthonormal ... More
The derivation of Bell inequalities for beablesSep 21 2000Jul 17 2003The derivation of Bell inequalities for beables is well-known to require a "no-conspiracy" assumption. This assumption is widely accepted, the alternative being correlations between instrument settings and hidden beables. Two further assumptions are identified ... More
Unary Classical MechanicsJan 02 2019Mar 20 2019Classical mechanics is presented here in a unary operator form, constructed using the binary multiplication and Poisson bracket operations that are given in a phase space formalism, then a Gibbs equilibrium state over this unary operator algebra is introduced, ... More
An atlas of coronal electron density at 5Rs I: Data processing and calibrationSep 10 2015Tomography of the solar corona can provide cruicial constraints for models of the low corona, unique information on changes in coronal structure and rotation rates, and a valuable boundary condition for models of the heliospheric solar wind. This is the ... More
The information-carrying capacity of certain quantum channelsJul 16 2010In this thesis we analyse the type of states and ensembles which achieve the capacity for certain quantum channels carrying classical information. We first concentrate on the product-state capacity of a particular quantum channel, that is, the capacity ... More
Rho-0 Meson Helicity Amplitude Ratios at HERMESJun 14 2012The study of {\rho}0 meson helicity amplitude ratios at HERMES shows that the amplitude hierarchy expected from pQCD is confirmed. The contribution of Unnatural Parity Exchange in the production of {\rho}0 mesons is significant at HERMES kinematics and ... More
Physics Updates from HERMESJan 08 2013The HERMES collaboration presents two sets of recent results: the first related to an extraction of the g2 nucleon structure function determined for DIS on a polarised target and the second related to the measurement of asymmetries related to the deeply ... More
Convergence properties of Donaldson's $T$-iterations on the Riemann sphereJun 28 2007Aug 25 2008In a recent paper Donaldson defines three operators on a space of Hermitian metrics on a complex projective manifold: $T, T_{\nu}, T_K.$ Iterations of these operators converge to balanced metrics, and these themselves approximate constant scalar curvature ... More
In polytopes, small balls about some vertex minimize perimeterApr 20 2004Dec 23 2006In (the surface of) a convex polytope P^n in R^n+1, for small prescribed volume, geodesic balls about some vertex minimize perimeter. This revision corrects a mistake in the mass bound argument in the proof of Theorem 3.8.
Comment on "A glance beyond the quantum model" [arXiv:0907.0372]Jan 27 2010The aim of "A glance beyond the quantum model" [arXiv:0907.0372] to modernize the Correspondence Principle is compromised by an assumption that a classical model must start with the idea of particles, whereas in empirical terms particles are secondary ... More
The direction of time in quantum field theoryOct 27 2008The algebra of observables associated with a quantum field theory is invariant under the connected component of the Lorentz group and under parity reversal, but it is not invariant under time reversal. If we take general covariance seriously as a long-term ... More
The straw man of quantum physicsOct 15 2008The violation of Bell inequalities by experiment has convinced physicists that we cannot maintain a classical view of the world. When we argue against the possibility of local realist hidden-variable models, however, the ubiquitous requirement of realism, ... More
An empirically equivalent random field for the quantized electromagnetic fieldAug 17 2009Oct 09 2011A random field that is empirically equivalent to the quantized electromagnetic field is constructed. A mapping between the creation and annihilation operator algebras of a random field and of the quantized electromagnetic field provides a functor between ... More
Lie random fieldsMar 18 2009The algebras of interacting "Lie random fields" that were introduced in J. Math. Phys. 48, 122302 (2007) are developed further. The conjecture that the vacuum vector defines a state over a Lie random field algebra is proved. The difference between Lie ... More
Violation of Bell inequalities through the coincidence-time loopholeJan 11 2008The coincidence-time loophole was identified by Larsson & Gill (Europhys. Lett. 67, 707 (2004)); a concrete model that exploits this loophole has recently been described by De Raedt et al. (Found. Phys., to appear). It is emphasized here that De Raedt ... More
Displacement deformed quantum fieldsOct 10 2006A displacement operator d_\zeta is introduced, verifying commutation relations [d_\zeta, a_f^\dagger]=[d_\zeta, a_f]=\zeta(f)d_\zeta with field creation and annihilation operators that verify [a_f,a_g]=0, [a_f,a_g^\dagger]=(g,f), as usual. f and g are ... More
The Levy-Gromov Isoperimetric Inequality in Convex Manifolds with BoundaryOct 10 2007We observe after Bayle and Rosales that the Levy-Gromov isoperimetric inequality generalizes to convex manifolds with boundary.
Mean action of periodic orbits of area-preserving annulus diffeomorphismsOct 11 2018Nov 08 2018An area-preserving diffeomorphism of an annulus has an "action function" which measures how the diffeomorphism distorts curves. The average value of the action function over the annulus is known as the Calabi invariant of the diffeomorphism, while the ... More
Quadratic twists of abelian varieties and disparity in Selmer ranksJun 19 2017We study the parity of 2-Selmer ranks in the family of quadratic twists of a fixed principally polarised abelian variety over a number field. Specifically, we determine the proportion of twists having odd (resp. even) 2-Selmer rank. This generalises work ... More
Unexpected Termination Switching and Polarity Compensation in LaAlO3/SrTiO3 heterostructuresJan 19 2018Polar crystals composed of charged ionic planes cannot exist in nature without acquiring surface changes to balance an ever-growing dipole. The necessary changes can manifest structurally or electronically. An electronic asymetry has long been observed ... More
Interior derivative estimates for the Kähler-Ricci flowJul 10 2011We give a maximum principle proof of interior derivative estimates for the K\"ahler-Ricci flow, assuming local uniform bounds on the metric.
Constructing Piecewise Flat Pseudo-Manifolds with Minimal Pseudo-FoliationsJul 28 2004Piecewise Euclidean structures (identified solid Euclidean polyhedra) on topological 3-dimensional manifolds and pseudo-manifolds are constructed so that they admit pseudo-foliations, a generalized type of foliation. The construction of non-manifold point ... More
Merger as Intermittent AccretionMay 08 2007Oct 01 2008The Self-Similar Secondary Infall Model (SSIM) is modified to simulate a merger event. The model encompass spherical versions of tidal stripping and dynamical friction that agrees with the Syer & White merger paradigm's behaviour. The SSIM shows robustness ... More
A theory of semiprimitive groupsJul 13 2016A transitive permutation group is semiprimitive if each of its normal subgroups is transitive or semiregular. Interest in this class of groups is motivated by two sources: problems arising in universal algebra related to collapsing monoids and the graph-restrictive ... More
On locally semiprimitive graphs and a theorem of WeissMay 06 2014Jan 14 2015In this paper we investigate graphs that admit a group acting arc-transitively such that the local action is semiprimitive with a regular normal nilpotent subgroup. This type of semiprimitive group is a generalisation of an affine group. We show that ... More
Accounting for Stochastic Fluctuations when Analysing Integrated Light of Star Clusters. I: First SystematicsMar 11 2010Apr 26 2010Star clusters are studied widely both as benchmarks for stellar evolution models and in their own right. Cluster age and mass distributions within galaxies are probes of star formation histories, and of cluster formation and disruption processes. The ... More
The Alex Catalogue, A Collection of Digital Texts with Automatic Methods for Acquisition and Cataloging, User-Defined Typography, Cross-searching of Indexed Content, and a Sense of CommunityFeb 02 1999This paper describes the Alex Catalogue of Electronic Texts, the only Internet-accessible collection of digital documents allowing the user to 1) dynamically create customized, typographically readable documents on demand, 2) search the content of one ... More
Erupting filaments with large enclosing flux tubes as sources of high-mass 3-part CMEs, and erupting filaments in the absence of enclosing flux tubes as sources of low-mass unstructured CMEsJun 10 2016The 3-part appearance of many CMEs arising from erupting filaments emerges from a large magnetic flux tube structure, consistent with the form of the erupting filament system. Other CMEs arising from erupting filaments lack a clear 3-part structure and ... More
Near-resonant optical forces beyond the two-level approximation for a continuous source of spin-polarized cold atomsJan 18 2013Mar 14 2013We propose a method to generate a source of spin-polarized cold atoms which are continuously extracted and guided from a magneto-optical trap using an atom-diode effect. We show that it is possible to create a pipe-like potential by overlapping two optical ... More
Strain effects on oxygen vacancy formation energy in perovskitesNov 28 2017Oxygen vacancy formation energy is an important quantity for enabling fast oxygen diffusion and oxygen catalysis in technologies like solid oxide fuel cells. Both previous literature in various systems and our calculations in LaMnO3, La0.75Sr0.25MnO3, ... More
Contests with a Non-Convex Strategy SpaceSep 12 2018Nov 28 2018We characterize the Nash equilibria of a class of two-player contests with "lumpy" effort. Our main result shows that under quite reasonable conditions, constraints on the players' choice sets heighten competition. This stands in sharp contrast to the ... More
The strong converse theorem for the product-state capacity of quantum channels with ergodic Markovian memoryFeb 26 2016Aug 26 2016Establishing the strong converse theorem for a communication channel confirms that the capacity of that channel, that is, the maximum achievable rate of reliable information communication, is the ultimate limit of communication over that channel. Indeed, ... More
The spin-statistics connection in classical field theoryJan 03 2006Sep 18 2006The spin-statistics connection is obtained for a simple formulation of a classical field theory containing even and odd Grassmann variables. To that end, the construction of irreducible canonical realizations of the rotation group corresponding to general ... More
Spin and Statistics in Classical MechanicsJan 14 2004The spin-statistics conection is obtained for classical point particles. The connection holds within pseudomechanics, a theory of particle motion that extends classical physics to include anticommuting Grassmann variables, and which exhibits classical ... More
A Bayesian Estimator for Linear Calibration Error Effects in Thermal Remote SensingJan 17 2005The Bayesian Land Surface Temperature estimator previously developed has been extended to include the effects of imperfectly known gain and offset calibration errors. It is possible to treat both gain and offset as nuisance parameters and, by integrating ... More
$Λ$\<-Trees and Their ApplicationsJan 01 1992To most mathematicians and computer scientists the word ``tree'' conjures up, in addition to the usual image, the image of a connected graph with no circuits. In the last few years various types of trees have been the subject of much investigation, but ... More
A nonlocal classical perspective on quantum electrodynamicsSep 05 2001The ideas behind the nonlocal classical statistical field theory model for the quantized Klein-Gordon field introduced in Morgan(2001, quant-ph/0106141) are extended to accommodate quantum electrodynamics. The anticommutation rules for the quantized Dirac ... More
Uniform Bounds for Solutions to Volume-Surface Reaction Diffusion SystemsDec 29 2015We consider a reaction-diffusion system where some components react and diffuse on the boundary of a region, while other components diffuse in the interior and react with those on the boundary through mass transport. We establish criteria guaranteeing ... More
Realising $π_\ast^e R$-algebras by global ring spectraApr 11 2019We approach a problem of realising algebraic objects in a certain universal equivariant stable homotopy theory; the global homotopy theory of Schwede \cite{s}. Specifically, for an (ultra-commutative) ring spectrum $R$, we consider which classes of ring ... More
Oscillation and synchronization of two quantum van der Pol oscillatorsJun 11 2015The synchronization properties of two self-sustained quantum oscillators are studied in the Wigner representation. Instead of considering the quantum limit of the quantum van-der-Pol master equation we derive the quantum master equation directly from ... More
Results on the quantitative mu-calculus qMuSep 15 2003The mu-calculus is a powerful tool for specifying and verifying transition systems, including those with both demonic and angelic choice; its quantitative generalisation qMu extends that to probabilistic choice. We show that for a finite-state system ... More
Efficient achievability for quantum protocols using decoupling theoremsJan 27 2014Feb 14 2014Proving achievability of protocols in quantum Shannon theory usually does not consider the efficiency at which the goal of the protocol can be achieved. Nevertheless it is known that protocols such as coherent state merging are efficiently achievable ... More
Global exact controllability of a 1D Schrödinger equations with a polarizability termSep 26 2013We consider a quantum particle in a 1D interval submitted to a potential. The evolution of this particle is controlled using an external electric field. Taking into account the so-called polarizability term in the model (quadratic with respect to the ... More
Notes on Geometric Measure Theory Applications to Image Processing; De-noising, Segmentation, Pattern, Texture, Lines, Gestalt and OcclusionMay 29 2006May 30 2006Regularization functionals that lower level set boundary length when used with L^1 fidelity functionals on signal de-noising on images create artifacts. These are (i) rounding of corners, (ii) shrinking of radii, (iii) shrinking of cusps, and (iv) non-smoothing ... More
An Improved Energy-Area Inequality for Harmonic Maps Using Image CurvatureJul 28 2004Aug 24 2004An ODE variational calculation shows that an image principle curvature ratio factor can raise the lower bound, 2(Image Area), on energy of a harmonic map of a surface into Rn. In certain situations, including all radially symmetry harmonic maps, equality ... More
MyLibrary: A Model for Implementing a User-centered, Customizable Interface to a Library's Collection of Information ResourcesFeb 02 1999The paper describes an extensible model for implementing a user-centered, customizable interface to a library's collection of information resources. This model, called MyLibrary, integrates the principles of librarianship (collection, organization, dissemination, ... More
Probing Dynamical Dark Energy with Press-Schechter Mass FunctionsMar 04 2007Measurement of accelerated expansion in the Universe led to propose a new cosmic fluid as its cause: dark energy. Its various incarnations offer a wealth of models whose relevance it is important to discriminate via contacts with observations. I will ... More
A note on reductions between compressed sensing guaranteesJun 02 2016Jun 05 2016In compressed sensing, one wishes to acquire an approximately sparse high-dimensional signal $x\in\mathbb{R}^n$ via $m\ll n$ noisy linear measurements, then later approximately recover $x$ given only those measurement outcomes. Various guarantees have ... More
Local controllability of 1D Schrödinger equations with bilinear control and minimal timeAug 27 2012Jan 16 2013We consider a linear Schr\"odinger equation, on a bounded interval, with bilinear control. Beauchard and Laurent proved that, under an appropriate non degeneracy assumption, this system is controllable, locally around the ground state, in arbitrary time. ... More
Parity and the Spin-Statistics ConnectionOct 06 2004The spin-statistics connection is obtained in a simple and elementary way for general causal fields by using the parity operation to exchange spatial coordinates in the scalar product of a locally commuting field operator, evaluated at position x, with ... More
Contests with a Non-Convex Strategy SpaceSep 12 2018Feb 20 2019We characterize the Nash equilibria of a class of two-player contests with "lumpy" effort. Our main result shows that under quite reasonable conditions, constraints on the players' choice sets heighten competition. This stands in sharp contrast to the ... More
Vertical waves in the solar neighbourhood in Gaia DR2Sep 10 2018Nov 07 2018The vertical structure and dynamics of stars in our local Galactic neighbourhood contains much information about the local distribution of visible and dark matter and of perturbations to the Milky Way disc. We use data on the positions and velocities ... More
Reconciling Graphs and Sets of SetsJul 18 2017Jul 25 2018We explore a generalization of set reconciliation, where the goal is to reconcile sets of sets. Alice and Bob each have a parent set consisting of $s$ child sets, each containing at most $h$ elements from a universe of size $u$. They want to reconcile ... More
Correction to Section 19.2 of Ricci Flow and the Poincare ConjectureDec 02 2015This note corrects a mistake in the original book in the evolution equations of total curvature for the curve-shrinking flow in an ambient Ricci Flow. The resulting upper bound for the evolution of total curvature is an exponential bound in time. The ... More