Results for "Cornelis Storm"

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Off-lattice Monte Carlo Simulation of Supramolecular Polymer ArchitecturesDec 24 2010We introduce an efficient, scalable Monte Carlo algorithm to simulate cross-linked architectures of freely-jointed and discrete worm-like chains. Bond movement is based on the discrete tractrix construction, which effects conformational changes that exactly ... More
Actin Remodeling and Polymerization Forces Control Dendritic Spine MorphologyOct 29 2015Oct 30 2015Dendritic spines are small membranous structures that protrude from the neuronal dendrite. Each spine contains a synaptic contact site that may connect its parent dendrite to the axons of neighboring neurons. Dendritic spines are markedly distinct in ... More
Accurate determination of elastic parameters for multi-component membranesDec 21 2006Jun 28 2007Heterogeneities in the cell membrane due to coexisting lipid phases have been conjectured to play a major functional role in cell signaling and membrane trafficking. Thereby the material properties of multiphase systems, such as the line tension and the ... More
Geometric localization in supported elastic strutsJun 11 2019Localized deformation patterns are a common motif in morphogenesis and are increasingly finding widespread applications in materials science, for instance as memory devices. Here we describe the emergence of spatially localized deformations in a minimal ... More
Theory of High-Force DNA Stretching and OverstretchingJun 27 2002Single molecule experiments on single- and double stranded DNA have sparked a renewed interest in the force-extension of polymers. The extensible Freely Jointed Chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded ... More
Curvature-induced cross-hatched order in two-dimensional semiflexible polymer networksJul 14 2015A recurring motif in the organization of biological tissues are networks of long, fibrillar protein strands effectively confined to cylindrical surfaces. Often, the fibers in such curved, quasi-2D geometries adopt a characteristic order: the fibers wrap ... More
Catch Bonding in the Forced Dissociation of a Polymer EndpointSep 07 2017Applying a force to certain supramolecular bonds may initially stabilize them, manifested by a lower dissociation rate. We show that this behavior, known as catch bonding and by now broadly reported in numerous biophysics bonds, is generically expected ... More
Crowding induced clustering under confinementJul 17 2015We present Langevin dynamics simulations that study the collective behavior of driven particles embedded in a densely packed background consisting of passive particles. Depending on the driving force, the densities of driven and passive particles, and ... More
The bend stiffness of S-DNADec 06 2002We formulate and solve a two-state model for the elasticity of nicked, double-stranded DNA that borrows features from both the Worm Like Chain and the Bragg--Zimm model. Our model is computationally simple, and gives an excellent fit to recent experimental ... More
Self-assembling multiblock amphiphiles: Molecular design, supramolecular structure, and mechanical propertiesJul 20 2015We perform off-lattice, canonical ensemble molecular dynamics simulations of the self-assembly of long segmented copolymers consisting of alternating, tunably attractive and hydrophobic {\em binder} domains, connected by hydrophilic {\em linker} chains ... More
Disorder, pre-stress and non-affinity in polymer 8-chain modelsJul 15 2015To assess the role of single-chain elasticity, non-affine strain fields and pre-stressed reference states we present and discuss the results of numerical and analytical analyses of modified 8-chain Arruda-Boyce model for cross-linked polymer networks. ... More
Confinement without boundaries: Anisotropic diffusion on the surface of a cylinderJul 14 2014Jul 21 2014Densely packed systems of thermal particles in curved geometries are frequently encountered in biological and microfluidic systems. In 2D systems, at sufficiently high surface coverage, diffusive motion is widely known to be strongly affected by physical ... More
Evidence for Slow Velocity Relaxation in Front Propagation in Rayleigh-Bénard ConvectionNov 02 2001Recent theoretical work has shown that so-called pulled fronts propagating into an unstable state always converge very slowly to their asymptotic speed and shape. In the the light of these predictions, we reanalyze earlier experiments by Fineberg and ... More
Teaching natural language to computersApr 29 2016Jun 28 2016"Natural Language," whether spoken and attended to by humans, or processed and generated by computers, requires networked structures that reflect creative processes in semantic, syntactic, phonetic, linguistic, social, emotional, and cultural modules. ... More
Beam-Beam Effects in the SPS Proton-Anti Proton ColliderOct 13 2014During the proton-anti proton collider run several experiments were carried out in order to understand the effect of the beam-beam interaction on backgrounds and lifetimes. In this talk a selection of these experiments will be presented. From these experiments, ... More
Determination of single-bond association kinetics by tethered particle motion: concept and simulationsFeb 06 2016Tethered particle motion (TPM) --- the motion of a micro- or nanoparticle tethered to a substrate by a macromolecule --- is a system that has proven extremely useful for its ability to reveal physical features of the tether, because the thermal motion ... More
A new construction of naturally reductive spacesMay 02 2016A new construction of naturally reductive spaces is presented. This construction gives a large amount of new families of naturally reductive spaces. First the infinitesimal models of the new naturally reductive spaces are constructed. A concrete transitive ... More
Structure theory of naturally reductive spacesOct 05 2018The main result of this paper is that every naturally reductive space can be explicitly constructed from the construction in \cite{Storm2018}. This gives us a general formula for any naturally reductive space and from this we prove reducibility and isomorphism ... More
Restricted Schur Polynomials and Finite N CountingOct 23 2008Restricted Schur polynomials have been posited as orthonormal operators for the change of basis from N=4 SYM to type IIB string theory [1,2,3,4]. In this letter we briefly expound the relationship found between the restricted Schurs and the operators ... More
How good are RR Lyrae and Cepheids really as Distance Indicators? The observational approachOct 06 2005A number of recent technical developments, including the Hipparcos satellite, the Hubble Space Telescope fine guidance sensors and long base line near-IR interferometry has made it possible to employ several largely geometrical methods to determine direct ... More
Persistence-driven durotaxis: Generic, directed motility in rigidity gradientsDec 18 2015Cells move differently on substrates with different elasticities. In particular, the persistence time of their motion is higher on stiffer substrates. We show that this behavior will result in a net transport of cells directed up a soft-to-stiff gradient. ... More
Weakly nonlinear subcritical instability of visco-elastic Poiseuille flowOct 01 2003It is well known that the Poiseuille flow of a visco-elastic polymer fluid between plates or through a tube is linearly stable in the zero Reynolds number limit, although the stability is weak for large Weissenberg numbers. In this paper we argue that ... More
Universal Algebraic Relaxation of Velocity and Phase in Pulled Fronts generating Periodic or Chaotic StatesAug 16 1999We investigate the asymptotic relaxation of so-called pulled fronts propagating into an unstable state. The ``leading edge representation'' of the equation of motion reveals the universal nature of their propagation mechanism and allows us to generalize ... More
Semiflexible Filamentous CompositesAug 30 2010Inspired by the ubiquity of composite filamentous networks in nature we investigate models of biopolymer networks that consist of interconnected floppy and stiff filaments. Numerical simulations carried out in three dimensions allow us to explore the ... More
An institutional approach to computational social creativityMay 08 2016Jun 25 2016Modelling the creativity that takes place in social settings presents a range of theoretical challenges. Mel Rhodes's classic "4Ps" of creativity, the "Person, Process, Product, and Press," offer an initial typology. Here, Rhodes's ideas are connected ... More
Persistence-driven durotaxis: Generic, directed motility in rigidity gradientsDec 18 2015Mar 08 2017Cells move differently on substrates with different elasticities. In particular, the persistence time of their motion is higher on stiffer substrates. We show that this behavior will result in a net transport of cells directed up a soft-to-stiff gradient. ... More
Sources, sinks and wavenumber selection in coupled CGL equations and experimental implications for counter-propagating wave systemsFeb 16 1999We study the coupled complex Ginzburg-Landau (CGL) equations for traveling wave systems in the regime where sources and sinks separate patches of left and right-traveling waves. We show that sources and sinks are the important coherent structures that ... More
Fluctuation-stabilized marginal networks and anomalous entropic elasticityApr 11 2013Aug 12 2013We study the elastic properties of thermal networks of Hookean springs. In the purely mechanical limit, such systems are known to have vanishing rigidity when their connectivity falls below a critical, isostatic value. In this work we show that thermal ... More
Fast DNA translocation through a solid-state nanoporeApr 28 2004We report translocation experiments on double-strand DNA through a silicon oxide nanopore. Samples containing DNA fragments with seven different lengths between 2000 to 96000 basepairs have been electrophoretically driven through a 10 nm pore. We find ... More
The classification of 7- and 8-dimensional naturally reductive spacesOct 08 2018A new method for classifying naturally reductive spaces is presented. This method relies on the structure theory of naturally reductive spaces developed in \cite{Storm2018a} and the new construction of naturally reductive spaces in \cite{Storm2018}. We ... More
Modeling the effect of intercalators on the high-force stretching behavior of DNADec 22 2015DNA is structurally and mechanically altered by the binding of intercalator molecules. Intercalation strongly affects the force-extension behavior of DNA, in particular the overstretching transition. We present a statistical model that captures all relevant ... More
Nonlinear Elasticity in Biological GelsJun 01 2004Unlike most synthetic materials, biological materials often stiffen as they are deformed. This nonlinear elastic response, critical for the physiological function of some tissues, has been documented since at least the 19th century, but the molecular ... More
Self-stresses control stiffness and stability in overconstrained disordered networksDec 03 2018We investigate the interplay between pre-stress and mechanical properties in random elastic networks. To do this in a controlled fashion, we introduce an algorithm for creating random freestanding frames that support exactly one state of self stress. ... More
Geometry and the onset of rigidity in a disordered networkSep 08 2017Disordered spring networks that are undercoordinated may abruptly rigidify when sufficient strain is applied. Since the deformation in response to applied strain does not change the generic quantifiers of network architecture - the number of nodes and ... More
Diffusion limits for a Markov modulated binomial counting processJan 11 2018Feb 04 2019In this paper we study limit behavior for a Markov-modulated (MM) binomial counting process, also called a binomial counting process under regime switching. Such a process naturally appears in the context of credit risk when multiple obligors are present. ... More
The Search for Computational IntelligenceJan 31 2015We define and explore in simulation several rules for the local evolution of generative rules for 1D and 2D cellular automata. Our implementation uses strategies from conceptual blending. We discuss potential applications to modelling social dynamics. ... More
Total variation distance and the Erdős-Turán law for random permutations with polynomially growing cycle weightsOct 20 2014We study the model of random permutations of $n$ objects with polynomially growing cycle weights, which was recently considered by Ercolani and Ueltschi, among others. Using saddle-point analysis, we prove that the total variation distance between the ... More
The curious moduli spaces of unmarked Kleinian surface groupsJun 30 2009Jul 31 2010Fixing a closed hyperbolic surface S, we define a moduli space AI(S) of unmarked hyperbolic 3-manifolds homotopy equivalent to S. This 3-dimensional analogue of the moduli space M(S) of unmarked hyperbolic surfaces homeomorphic to S has bizarre local ... More
The Zeta Function of a HypergraphAug 30 2006We generalize the Ihara-Selberg zeta function to hypergraphs in a natural way. Hashimoto's factorization results for biregular bipartite graphs apply, leading to exact factorizations. For $(d,r)$-regular hypergraphs, we show that a modified Riemann hypothesis ... More
Some graph properties determined by edge zeta functionsAug 14 2007Stark and Terras introduced the edge zeta function of a finite graph in 1996. The edge zeta function is the reciprocal of a polynomial in twice as many variables as edges in the graph and can be computed in polynomial time. We look at graph properties ... More
The barycenter method on singular spacesJan 09 2003Mar 05 2009Bonahon conjectured that compact convex cores with totally geodesic boundary uniquely minimize volume over all hyperbolic 3-manifolds in the same homotopy class. This paper proves Bonahon's conjecture. The proofs extend the techniques of Besson-Courtois-Gallot. ... More
Fission of a multiphase membrane tubeApr 19 2004Sep 01 2004A common mechanism for intracellular transport is the use of controlled deformations of the membrane to create spherical or tubular buds. While the basic physical properties of homogeneous membranes are relatively well-known, the effects of inhomogeneities ... More
Forced transport of deformable containers through narrow constrictionsMay 06 2014Nov 19 2014We study, numerically and analytically, the forced transport of deformable containers through a narrow constriction. Our central aim is to quantify the competition between the constriction geometry and the active forcing, regulating whether and at which ... More
NNexus ReloadedApr 25 2014Interlinking knowledge is one of the cornerstones of online collaboration. While wiki systems typically rely on links supplied by authors, in the early 2000s the mathematics encyclopedia at introduced a feature that provides automatic linking ... More
X575: writing rengas with web servicesJun 25 2016Our software system simulates the classical collaborative Japanese poetry form, renga, made of linked haikus. We used NLP methods wrapped up as web services. Our experiments were only a partial success, since results fail to satisfy classical constraints. ... More
Charles Sanders Peirce and the Abduction of Einstein: On the Comprehensibility of the WorldOct 01 2016Einstein was deeply puzzled by the success of natural science, and thought that we would never be able to explain it. He came to this conclusion on the ground that we cannot extract the basic laws of physics from experience using induction or deduction, ... More
On the impact of quantum computing technology on future developments in high-performance scientific computingMay 21 2017Jun 19 2017Quantum computing technologies have become a hot topic in academia and industry receiving much attention and financial support from all sides. Building a quantum computer that can be used practically is in itself an outstanding challenge that has become ... More
Spiral Density Waves in a Young Protoplanetary DiskOct 17 2016Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the ... More
Grain Growth in the Circumstellar Disks of the Young Stars CY Tau and DoAr 25Sep 24 2015We present new results from the Disks@EVLA program for two young stars: CY Tau and DoAr 25. We trace continuum emission arising from their circusmtellar disks from spatially resolved observations, down to tens of AU scales, at {\lambda} = 0.9, 2.8, 8.0, ... More
Integrability and Applications of the Exactly-Solvable Haldane-Shastry One-Dimensional Quantum Spin ChainSep 30 1995Recently, the one dimensional model of $N$ spins with $S=\frac{1}{2}$ on a circle, interacting with an exchange that falls off with the inverse square of the separation: $H_{\rm ISE} =\sum_{i\neq j} \frac{1}{[\frac{N}{\pi} \sin(\frac{i-j}{N}\pi)]^2}(\svec_i\cdot ... More
Implementing feedback in creative systems: A workshop approachMay 26 2015One particular challenge in AI is the computational modelling and simulation of creativity. Feedback and learning from experience are key aspects of the creative process. Here we investigate how we could implement feedback in creative systems using a ... More
Hyperbolic convex cores and simplicial volumeSep 17 2004Mar 09 2009This paper investigates the relationship between the topology of hyperbolizable 3-manifolds M with incompressible boundary and the volume of hyperbolic convex cores homotopy equivalent to M. Specifically, it proves a conjecture of Bonahon stating that ... More
The order of large random permutations with cycle weightsMay 18 2015The order $O_n(\sigma)$ of a permutation $\sigma$ of $n$ objects is the smallest integer $k \geq 1$ such that the $k$-th iterate of $\sigma$ gives the identity. A remarkable result about the order of a uniformly chosen permutation is due to Erd\"os and ... More
The KPZ Equation on the Real LineAug 01 2018We prove existence and uniqueness of distributional solutions to the KPZ equation globally in space and time, with techniques from paracontrolled analysis. Our main tool for extending the analysis on the torus to the full space is a comparison result ... More
The KPZ Equation on the Real LineAug 01 2018Feb 20 2019We prove existence and uniqueness of distributional solutions to the KPZ equation globally in space and time, with techniques from paracontrolled analysis. Our main tool for extending the analysis on the torus to the full space is a comparison result ... More
Sources, sinks and holes in a one-dimensional traveling wave convection experimentNov 13 2001Jan 29 2003We study dynamical behavior of local structures, such as sources and holes, in traveling wave patterns in a very long (2 m) heated wire convection experiment. The {\em sources} undergo a transition from stable coherent behavior to erratic behavior when ... More
Rapid Variations of Narrow Absorption Line Components in the Spectrum of P CygniApr 21 2003We report the detection of rapid wavelength and intensity variations of narrow components in absorption line profiles of the hot galactic supergiant P Cygni. During most of the time, in one week of observations, there were two such components present. ... More
A Rough Super-Brownian MotionMay 14 2019We study the scaling limit of a branching random walk in static random environment in dimension $d=1,2$ and show that it is given by a super-Brownian motion in a white noise potential. In dimension $1$ we characterize the limit as the unique weak solution ... More
Infinitesimal rigidity of a compact hyperbolic 4-orbifold with totally geodesic boundarySep 21 2008Kerckhoff and Storm conjectured that compact hyperbolic n-orbifolds with totally geodesic boundary are infinitesimally rigid when n>3. This paper verifies this conjecture for a specific example based on the 4-dimensional hyperbolic 120-cell.
Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured QuasarsJan 24 2008Recent work has suggested that the fraction of obscured AGN declines with increasing luminosity, but it has been difficult to quantify this trend. Here, we attempt to measure this fraction as a function of luminosity by studying the ratio of mid-infrared ... More
A critical analysis of shock models for chondrule formationAug 20 2014In recent years many models of chondrule formation have been proposed. One of those models is the processing of dust in shock waves in protoplanetary disks. In this model, the dust and the chondrule precursors are overrun by shock waves, which heat them ... More
The Communication-Hiding Conjugate Gradient Method with Deep PipelinesJan 15 2018Krylov subspace methods are among the most efficient present-day solvers for large scale linear algebra problems. Nevertheless, classic Krylov subspace method algorithms do not scale well on massively parallel hardware due to the synchronization bottlenecks ... More
Estimation in linear errors-in-variables models with unknown error distributionDec 03 2018Parameter estimation in linear errors-in-variables models typically requires that the measurement error distribution be known (or estimable from replicate data). A generalized method of moments approach can be used to estimate model parameters in the ... More
An IGA Framework for PDE-Based Planar Parameterization with Arbitrary Interface ContinuityApr 05 2019The first step towards applying isogeometric analysis techniques to solve PDE problems on a given domain consists in generating an analysis-suitable mapping operator between parametric and physical domains with one or several patches from no more than ... More
Gamma Rays from Star Formation in Clusters of GalaxiesJun 08 2012Jun 21 2012Star formation in galaxies is observed to be associated with gamma-ray emission. The detection of gamma rays from star-forming galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation ... More
Large cycles and a functional central limit theorem for generalized weighted random permutationsFeb 24 2013The objects of our interest are the so-called $A$-permutations, which are permutations whose cycle length lie in a fixed set $A$. They have been extensively studied with respect to the uniform or the Ewens measure. In this paper, we extend some classical ... More
Exact ICL maximization in a non-stationary time extension of the latent block model for dynamic networksJun 12 2015The latent block model (LBM) is a flexible probabilistic tool to describe interactions between node sets in bipartite networks, but it does not account for interactions of time varying intensity between nodes in unknown classes. In this paper we propose ... More
Finitely generated subgroups of lattices in PSL(2,C)Apr 21 2005Let G be a lattice in PSL(2,C). The pro-normal topology on G is defined by taking all cosets of non-trivial normal subgroups as a basis. This topology is finer than the pro-finite topology, but it is not discrete. We prove that every finitely generated ... More
Lipschitz minimality of Hopf fibrations and Hopf vector fieldsSep 28 2010Given a Hopf fibration of a round sphere by parallel great subspheres, we prove that the projection map to the base space is, up to isometries of domain and range, the unique Lipschitz constant minimizer in its homotopy class. Similarly, given a Hopf ... More
Moduli spaces of hyperbolic 3-manifolds and dynamics on character varietiesNov 09 2009Sep 13 2010The space AH(M) of marked hyperbolic 3-manifold homotopy equivalent to a compact 3-manifold with boundary M sits inside the PSL_2(C)-character variety X(M) of \pi_1(M). We study the dynamics of the action of Out(\pi_1(M)) on both AH(M) and X(M). The nature ... More
Entanglement in ground and excited states of gapped fermion systems and their relationship with fermi surface and thermodynamic equilibrium propertiesAug 28 2013Sep 12 2013We study bipartite entanglement entropies in the ground and excited states of model fermion systems, where a staggered potential, $\mu_s$, induces a gap in the spectrum. Ground state entanglement entropies satisfy the `area law', and the `area-law' coefficient ... More
Proceedings of the 3rd Workshop on Domain-Specific Language Design and Implementation (DSLDI 2015)Aug 14 2015The goal of the DSLDI workshop is to bring together researchers and practitioners interested in sharing ideas on how DSLs should be designed, implemented, supported by tools, and applied in realistic application contexts. We are both interested in discovering ... More
WISEA J064750.85-154616.4: a new nearby L/T transition dwarfJun 04 2014Aims: Our aim is to detect and classify previously overlooked brown dwarfs in the solar neighbourhood. Methods: We performed a proper motion search among bright sources observed with the Wide-field Infrared Survey Explorer (WISE) that are also seen in ... More
Local rigidity of hyperbolic manifolds with geodesic boundaryJun 13 2009Let W be a compact hyperbolic n-manifold with totally geodesic boundary. We prove that if n>3 then the holonomy representation of pi_1 (W) into the isometry group of hyperbolic n-space is infinitesimally rigid.
From the hyperbolic 24-cell to the cuboctahedronMay 28 2008We describe a family of 4-dimensional hyperbolic orbifolds, constructed by deforming an infinite volume orbifold obtained from the ideal, hyperbolic 24-cell by removing two walls. This family provides an infinite number of infinitesimally rigid, infinite ... More
Formation of planetary cores at Type I migration trapsJan 05 2011One of the longstanding unsolved problems of planet formation is how solid bodies of a few decimeters in size can "stick" to form large planetesimals. This is known as the "meter size barrier". In recent years it has become increasingly clear that some ... More
The first stages of planet formation in binary systems: How far can dust coagulation proceed?Oct 20 2010We examine the first phase of the core accretion model, namely the dust growth/fragmentation in binary systems. In our model, a gas and dust disk is present around the primary star and is perturbed by the secondary. We study the effects of a secondary ... More
Research evaluation per discipline: a peer-review method and its outcomesJul 26 2013This paper describes the method for ex-post peer review evaluation per research discipline used at the Vrije Universiteit Brussel (VUB) and summarizes the outcomes obtained from it. The method produces pertinent advice and triggers responses - at the ... More
An EM Algorithm for Estimating an Oral Reading Speed and Accuracy ModelMay 30 2017This study proposes a two-part model that includes components for reading accuracy and reading speed. The speed component is a log-normal factor model, for which speed data are measured by reading time for each sentence being assessed. The accuracy component ... More
The Communication-Hiding Conjugate Gradient Method with Deep PipelinesJan 15 2018Jan 28 2019Krylov subspace methods are among the most efficient solvers for large scale linear algebra problems. Nevertheless, classic Krylov subspace algorithms do not scale well on massively parallel hardware due to synchronization bottlenecks. Communication-hiding ... More
The Impact of Dust Evolution and Photoevaporation on Disk DispersalFeb 25 2015Protoplanetary disks are dispersed by viscous evolution and photoevaporation in a few million years; in the interim small, sub-micron sized dust grains must grow and form planets. The time-varying abundance of small grains in an evolving disk directly ... More
Modelling time evolving interactions in networks through a non stationary extension of stochastic block modelsSep 08 2015In this paper, we focus on the stochastic block model (SBM),a probabilistic tool describing interactions between nodes of a network using latent clusters. The SBM assumes that the networkhas a stationary structure, in which connections of time varying ... More
Exact ICL maximization in a non-stationary temporal extension of the stochastic block model for dynamic networksMay 09 2016Jul 10 2017The stochastic block model (SBM) is a flexible probabilistic tool that can be used to model interactions between clusters of nodes in a network. However, it does not account for interactions of time varying intensity between clusters. The extension of ... More
Quark-gluon Jet Discrimination At CMSSep 10 2014Many physics analyses at the LHC are looking into processes where the signal jets are originating from quarks, while jets in the background are more gluon enriched. Based on observables sensitive to fundamental differences in the fragmentation properties ... More
On the wavelets-based SWIFT method for backward stochastic differential equationsNov 09 2016We propose a numerical algorithm for backward stochastic differential equations based on time discretization and trigonometric wavelets. This method combines the effectiveness of Fourier-based methods and the simplicity of a wavelet-based formula, resulting ... More
Numerically Stable Recurrence Relations for the Communication Hiding Pipelined Conjugate Gradient MethodFeb 08 2019May 15 2019Pipelined Krylov subspace methods (also referred to as communication-hiding methods) have been proposed in the literature as a scalable alternative to classic Krylov subspace algorithms for iteratively computing the solution to a large linear system in ... More
Exact ICL maximization in a non-stationary temporal extension of the stochastic block model for dynamic networksMay 09 2016The stochastic block model (SBM) is a flexible probabilistic tool that can be used to model interactions between clusters of nodes in a network. However, it does not account for interactions of time varying intensity between clusters. The extension of ... More
Modeling dust growth in protoplanetary disks: The breakthrough caseJun 03 2014Simple toy models are often not sufficient to cover the complexity of the dust coagulation process, and a number of numerical approaches are therefore used, among which integration of the Smoluchowski equation and various versions of Monte Carlo algorithm ... More
Numerically Stable Recurrence Relations for the Communication Hiding Pipelined Conjugate Gradient MethodFeb 08 2019Pipelined Krylov subspace methods (also referred to as communication-hiding methods) have been proposed in the literature as a scalable alternative to classic Krylov subspace algorithms for iteratively computing the solution to a large linear system in ... More
Efficient Computation of Various Valuation Adjustments Under Local Lévy ModelsMay 05 2019Various valuation adjustments, or XVAs, can be written in terms of non-linear PIDEs equivalent to FBSDEs. In this paper we develop a Fourier-based method for solving FBSDEs in order to efficiently and accurately price Bermudan derivatives, including options ... More
SkyFACT: High-dimensional modeling of gamma-ray emission with adaptive templates and penalized likelihoodsMay 11 2017Aug 21 2017We present SkyFACT (Sky Factorization with Adaptive Constrained Templates), a new approach for studying, modeling and decomposing diffuse gamma-ray emission. Like most previous analyses, the approach relies on predictions from cosmic-ray propagation codes ... More
Quaternionic Heisenberg groups as naturally reductive homogeneous spacesMar 28 2015In this note, we describe the geometry of the quaternionic Heisenberg groups from a Riemannian viewpoint. We show, in all dimensions, that they carry an almost $3$-contact metric structure which allows us to define the metric connection that equips these ... More
Exact solutions to the nonlinear Schrödinger equationAug 19 2009A review of a recent method is presented to construct certain exact solutions to the focusing nonlinear Schr\"odinger equation on the line with a cubic nonlinearity. With motivation by the inverse scattering transform and help from the state-space method, ... More
Modelling serendipity in a computational contextNov 03 2014Jul 27 2016Building on a survey of previous theories of serendipity and creativity, we advance a model of serendipitous occurrences, and a definition of the serendipity potential of a system. Practitioners can use these theoretical tools to evaluate a computational ... More
Pricing options and computing implied volatilities using neural networksJan 25 2019This paper proposes a data-driven approach, by means of an Artificial Neural Network (ANN), to value financial options and to calculate implied volatilities with the aim of accelerating the corresponding numerical methods. With ANNs being universal function ... More
Forming chondrules in impact splashes. I. Radiative cooling modelJan 23 2015The formation of chondrules is one of the oldest unsolved mysteries in meteoritics and planet formation. Recently an old idea has been revived: the idea that chondrules form as a result of collisions between planetesimals in which the ejected molten material ... More
Chemistry and line emission of outer protoplanetary disksSep 21 2005The structure and chemistry of protoplanetary disks depends strongly on the nature of the central star around which it has formed. The dust temperature is mainly set by the stellar luminosity, while the chemistry of the upper disk layers depends on the ... More
Synchrotron Emission from Dark Matter Annihilation: Predictions for Constraints from Non-detections of Galaxy Clusters with New Radio SurveysJul 04 2016Mar 21 2017The annihilation of dark matter particles is expected to yield a broad radiation spectrum via the production of Standard Model particles in astrophysical environments. In particular, electrons and positrons from dark matter annihilation produce synchrotron ... More
On the progressive hardening of the cosmic-ray proton spectrum in the inner GalaxyJul 12 2018Spatial variations of the average properties that characterize the hadronic component of the diffuse Galactic cosmic-ray sea, in particular the spectral slope and normalization, may unveil critical information about their confinement mechanism in the ... More
Imaging flux distributions around superconductors: Geometrical susceptibility in the Meissner stateNov 12 2013Experiment and analytical calculations show that the demagnetizing field of a superconductor is a sensitive probe of quantities otherwise difficult to measure, such as the sample-probe distance in flux-density imaging experiments, and the field of first ... More