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Results for "Henk A. Dijkstra"

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Resonances in a Chaotic Attractor Crisis of the Lorenz FlowMay 23 2017Local bifurcations of stationary points and limit cycles have successfully been characterized in terms of the critical exponents of these solutions. Lyapunov exponents and their associated covariant Lyapunov vectors have been proposed as tools for supporting ... More
An early warning indicator for atmospheric blocking events using transfer operatorsFeb 03 2015Mar 14 2015The existence of persistent midlatitude atmospheric flow regimes with time-scales larger than 5-10 days and indications of preferred transitions between them motivates to develop early warning indicators for such regime transitions. In this paper, we ... More
Crisis of the Chaotic Attractor of a Climate Model: A Transfer Operator ApproachJul 08 2015Dec 13 2017The destruction of a chaotic attractor leading to rough changes in the dynamics of a dynamical system is studied. Local bifurcations are characterised by a single or a pair of characteristic exponents crossing the imaginary axis. The approach of such ... More
On the state dependency of fast feedback processes in (palaeo) climate sensitivityMar 21 2014Apr 30 2014Palaeo data have been frequently used to determine the equilibrium (Charney) climate sensitivity $S^a$, and - if slow feedback processes (e.g. land ice-albedo) are adequately taken into account - they indicate a similar range as estimates based on instrumental ... More
Mixing Spectrum in Reduced Phase Spaces of Stochastic Differential Equations. Part II: Stochastic Hopf BifurcationMay 22 2017The spectrum of the Markov semigroup of a diffusion process, referred to as the mixing spectrum, provides a detailed characterization of the dynamics of statistics such as the correlation function and the power spectrum. Stochastic analysis techniques ... More
The sensitivity and stability of the ocean's thermohaline circulation to finite amplitude perturbationsFeb 10 2007Within a simple model context, the sensitivity and stability of the thermohaline circulation to finite amplitude perturbations is studied. A new approach is used to tackle this nonlinear problem. The method is based on the computation of the so-called ... More
A Climate Network Based Stability Index for El Niño VariabilityMar 18 2015Most of the existing prediction methods gave a false alarm regarding the El Ni\~no event in 2014. A crucial aspect is currently limiting the success of such predictions, i.e. the stability of the slowly varying Pacific climate. This property determines ... More
Deep ocean early warning signals of an Atlantic MOC collapseMay 06 2014The Atlantic Meridional Overturning Circulation (MOC) is a crucial part of the climate system because of its associated northward heat transport. The present-day MOC is sensitive to freshwater anomalies and may collapse to a state with a strongly reduced ... More
Crisis of the Chaotic Attractor of a Climate Model: A Transfer Operator ApproachJul 08 2015The destruction of a chaotic attractor leading to a rough change in the dynamics of a system as a control parameter is smoothly varied is studied. While bifurcations involving non-chaotic invariant sets, such as fixed points or periodic orbits, can be ... More
Constraining Reionization with Lyman Alpha Emitting GalaxiesNov 04 2015Neutral diffuse intergalactic gas that existed during the Epoch of Reionization (EoR) suppresses Lyman Alpha (Lya) flux emitted by background galaxies. In this chapter I summarise the increasing observational support for the claim that Lya photons emitted ... More
New methods to bound the critical probability in fractal percolationOct 15 2012Oct 07 2013Fractal percolation has been introduced by Mandelbrot in 1974. We study the two-dimensional case, with integer subdivision index M and survival probability p. It is well known that there exists a non-trivial critical value p_c(M) such that a.s. the largest ... More
Large time-dependent coercivity and resistivity modification under sustained voltage application in a Pt/Co/AlOx/Pt junctionOct 29 2014The coercivity and resistivity of a Pt/Co/AlOx/Pt junction are measured under sustained voltage application. High bias voltages of either polarity are determined to cause a strongly enhanced, reversible coercivity modification compared to low voltages. ... More
Using Network Theory and Machine Learning to predict El NiñoMar 27 2018Aug 10 2018The skill of current predictions of the warm phase of the El Ni\~no Southern Oscillation (ENSO) reduces significantly beyond a lag of six months. In this paper, we aim to increase this prediction skill at lags up to one year. The new method to do so combines ... More
Effects of Drake Passage on a strongly eddying global oceanOct 14 2015The climate impact of ocean gateway openings during the Eocene-Oligocene transition is still under debate. Previous model studies employed grid resolutions at which the impact of mesoscale eddies has to be parameterized. We present results of a state-of-the-art ... More
Derivation of Delay Equation Climate Models Using the Mori-Zwanzig FormalismFeb 08 2019Models incorporating delay have been frequently used to understand climate variability phenomena, but often the delay is introduced through an ad-hoc physical reasoning, such as the propagation time of waves. In this paper, the Mori-Zwanzig formalism ... More
Common and Distinct Components in Data FusionJul 08 2016In many areas of science multiple sets of data are collected pertaining to the same system. Examples are food products which are characterized by different sets of variables, bio-processes which are on-line sampled with different instruments, or biological ... More
Foundations of Descriptive and Inferential StatisticsFeb 11 2013Aug 30 2015These lecture notes were written with the aim to provide an accessible though technically solid introduction to the logic of systematical analyses of statistical data to undergraduate and to postgraduate students, in particular in the Social Sciences ... More
Altmetrics as traces of the computerization of the research processOct 17 2015I propose a broad, multi-dimensional conception of altmetrics, namely as traces of the computerization of the research process. Computerization should be conceived in its broadest sense, including all recent developments in ICT and software, taking place ... More
An Open Ended TreeDec 15 2003An open ended list is a well known data structure in Prolog programs. It is frequently used to represent a value changing over time, while this value is referred to from several places in the data structure of the application. A weak point in this technique ... More
Topological invariance of the sign of the Lyapunov exponents in one-dimensional mapsSep 06 2004Nov 02 2004We explore some properties of Lyapunov exponents of measures preserved by smooth maps of the interval, and study the behaviour of the Lyapunov exponents under topological conjugacy.
Subideal Border BasesMay 07 2009In modeling physical systems it is sometimes useful to construct border bases of 0-dimensional polynomial ideals which are contained in the ideal generated by a given set of polynomials. We define and construct such subideal border bases, provide some ... More
Slow and Ordinary Provability for Peano ArithmeticFeb 04 2016Jun 06 2016The notion of slow provability for Peano Arithmetic ($\mathsf{PA}$) was introduced by S.D. Friedman, M. Rathjen, and A. Weiermann. They studied the slow consistency statement $\mathrm{Con}_{\mathsf{s}}$ that asserts that a contradiction is not slow provable ... More
Dynamic Transitions of Surface Tension Driven ConvectionMay 05 2011We study the well-posedness and dynamic transitions of the surface tension driven convection in a three-dimensional (3D) rectangular box with non-deformable upper surface and with free-slip boundary conditions. It is shown that as the Marangoni number ... More
Iran's scientific dominance and the emergence of South-East Asian countries as scientific collaborators in the Persian Gulf RegionFeb 15 2016Apr 04 2016A longitudinal bibliometric analysis of publications indexed in Thomson Reuters' Incites and Elsevier's Scopus, and published from Persian Gulf States and neighbouring Middle East countries, shows clear effects of major political events during the past ... More
An Introduction to Business MathematicsSep 11 2015Sep 16 2015These lecture notes provide a self-contained introduction to the mathematical methods required in a Bachelor degree programme in Business, Economics, or Management. In particular, the topics covered comprise real-valued vector and matrix algebra, systems ... More
Phase behavior of hard spheres confined between parallel hard plates: Manipulation of colloidal crystal structures by confinementApr 06 2006Jun 11 2006We study the phase behavior of hard spheres confined between two parallel hard plates using extensive computer simulations. We determine the full equilibrium phase diagram for arbitrary densities and plate separations from one to five hard-sphere diameters ... More
A Maintainability Checklist for SpreadsheetsJan 30 2014Spreadsheets are widely used in industry, because they are flexible and easy to use. Often, they are even used for business-critical applications. It is however difficult for spreadsheet users to correctly assess the maintainability of spreadsheets. Maintainability ... More
Transience and thermodynamic formalism for infinitely branched interval mapsApr 28 2011We study a one-parameter family of countably piecewise linear interval maps, which, although Markov, fail the `large image property'. This leads to conservative as well as dissipative behaviour for different maps in the family with respect to Lebesgue. ... More
Bias-voltage dependence of the magneto-resistance in ballistic vacuum tunneling: Theory and application to planar Co(0001) junctionsMay 22 2003Motivated by first-principles results for jellium and by surface-barrier shapes that are typically used in electron spectroscopies, the bias voltage in ballistic vacuum tunneling is treated in a heuristic manner. The presented approach leads in particular ... More
Correlated fractal percolation and the Palis conjectureOct 30 2009Let F1 and F2 be independent copies of correlated fractal percolation, with Hausdorff dimensions dimH(F1) and dimH(F2). Consider the following question: does dimH(F1)+dimH(F2)>1 imply that their algebraic difference F1-F2 will contain an interval? The ... More
Return time statistics for invariant measures for interval maps with positive Lyapunov exponentAug 02 2007Apr 20 2009We prove that multimodal maps with an absolutely continuous invariant measure have exponential return time statistics around a.e. point. We also show a `polynomial Gibbs property' for these systems, and that the convergence to the entropy in the Ornstein-Weiss ... More
Lyman Alpha Driven Outflows Around Star Forming GalaxiesJul 16 2008Sep 11 2008We present accurate Monte-Carlo calculations of Lyman Alpha (hereafter Lya) radiation pressure in a range of models which represent galaxies during various epochs of our Universe. We show that the radiation force that Lya photons exert on hydrogen gas ... More
A Blichfeldt-type inequality for the surface areaMay 15 2007In 1921 Blichfeldt gave an upper bound on the number of integral points contained in a convex body in terms of the volume of the body. More precisely, he showed that $#(K\cap\Z^n)\leq n! \vol(K)+n$, whenever $K\subset\R^n$ is a convex body containing ... More
Linear, third- and fifth-order nonlinear spectroscopy of a charge transfer system coupled to an underdamped vibrationFeb 23 2015We study hole, electron and exciton transport in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations ... More
Dynamic Transitions of Quasi-Geostrophic Channel FlowFeb 11 2015The main aim of this paper is to describe the dynamic transitions in flows described by the two-dimensional, barotropic vorticity equation in a periodic zonal channel. In \cite{CGSW03}, the existence of a Hopf bifurcation in this model as the Reynolds ... More
Tuning magnetic chirality by dipolar interactionsApr 03 2019Chiral magnetism has gained enormous interest in recent years because of the anticipated wealth of applications in nanoelectronics. The demonstrated stabilization of chiral magnetic domain walls and skyrmions has been attributed to the actively investigated ... More
Intrinsic unpredictability of strong El Niño eventsJul 09 2016The El Ni\~no-Southern Oscillation (ENSO) is a mode of interannual variability in the coupled equatorial ocean/atmosphere Pacific. El Ni\~no describes a state in which sea surface temperatures in the eastern Pacific increase and upwelling of colder, deep ... More
High-Performance Distributed Multi-Model / Multi-Kernel Simulations: A Case-Study in Jungle ComputingMar 01 2012High-performance scientific applications require more and more compute power. The concurrent use of multiple distributed compute resources is vital for making scientific progress. The resulting distributed system, a so-called Jungle Computing System, ... More
Unified functional network and nonlinear time series analysis for complex systems science: The pyunicorn packageJul 02 2015Apr 06 2016We introduce the \texttt{pyunicorn} (Pythonic unified complex network and recurrence analysis toolbox) open source software package for applying and combining modern methods of data analysis and modeling from complex network theory and nonlinear time ... More
Notes on the roots of Ehrhart polynomialsJun 04 2006We determine lattice polytopes of smallest volume with a given number of interior lattice points. We show that the Ehrhart polynomials of those with one interior lattice point have largest roots with norm of order n^2, where n is the dimension. This improves ... More
Pressure function and limit theorems for almost Anosov flowsNov 20 2018We obtain limit theorems (Stable Laws and Central Limit Theorems, both Gaussian and non-Gaussian) and thermodynamic properties for a class of non-uniformly hyperbolic flows: almost Anosov flows, constructed here. The proofs of the limit theorems for these ... More
Finite-size scaling in the canonical ensembleAug 15 2005We investigate the critical scaling behavior of finite systems in the canonical ensemble. The essential difference with the grand canonical ensemble. i.e., the constraint on the number of particles, is already known to lead to the Fisher renormalization ... More
A discrete version of Koldobsky's slicing inequalityNov 09 2015Let $\# K$ be a number of integer lattice points contained in a set $K$. In this paper we prove that for each $d\in {\mathbb N}$ there exists a constant $C(d)$ depending on $d$ only, such that for any origin-symmetric convex body $K \subset {\mathbb R}^d$ ... More
Semi-passivity and synchronization of diffusively coupled neuronal oscillatorsMar 20 2009We discuss synchronization in networks of neuronal oscillators which are interconnected via diffusive coupling, i.e. linearly coupled via gap junctions. In particular, we present sufficient conditions for synchronization in these networks using the theory ... More
Lyman Alpha Radiation From Collapsing Protogalaxies I: Characteristics of the Emergent SpectrumOct 13 2005Jun 14 2006We present Monte Carlo calculations of Lyman alpha (Lya) radiative transfer through collapsing gas clouds, representing proto-galaxies that are caught in the process of their assembly. Such galaxies produce Lya flux over an extended solid angle from a ... More
The pressure function for infinite equilibrium measuresNov 14 2017Oct 09 2018Assume that $(X,f)$ is a dynamical system and $\phi:X \to [-\infty, \infty)$ is a potential such that the $f$-invariant measure $\mu_\phi$ equivalent to $\phi$-conformal measure is infinite, but that there is an inducing scheme $F = f^\tau$ with a finite ... More
Integrality Gaps of Integer Knapsack ProblemsNov 11 2016We obtain optimal lower and upper bounds for the (additive) integrality gaps of integer knapsack problems. In a randomised setting, we show that the integrality gap of a "typical" knapsack problem is drastically smaller than the integrality gap that occurs ... More
Goldstone modes in Lyapunov spectra of hard sphere systemsDec 20 2003Apr 29 2004In this paper, we demonstrate how the Lyapunov exponents close to zero of a system of many hard spheres can be described as Goldstone modes, by using a Boltzmann type of approach. At low densities, the correct form is found for the wave number dependence ... More
The boundary between long-range and short-range critical behaviorDec 27 2001We investigate phase transitions of two-dimensional Ising models with power-law interactions, using an efficient Monte Carlo algorithm. For slow decay, the transition is of the mean-field type; for fast decay, it belongs to the short-range Ising universality ... More
Factorized sectorial relations, their maximal sectorial extensions, and form sumsMar 07 2019In this paper sectorial operators, or more generally, sectorial relations and their maximal sectorial extensions in a Hilbert space ${\mathfrak H}$ are considered. The particular interest is in sectorial relations $S$, which can be expressed in the factorized ... More
The Impact of The IGM on High-Redshift Lyman Alpha Emission LinesJan 23 2007May 04 2007We calculate the impact of the intergalactic medium (IGM) on the observed Lyman alpha lines (hereafter Lya) emitted by galaxies in an ionised IGM at z>4. Our model accounts for gas clumping in the IGM and for the fact that high-redshift galaxies reside ... More
Non-trivial topological valence bands of common diamond and zinc-blende semiconductorsApr 10 2019The diamond and zinc-blende semiconductors are well-known and have been widely studied for decades. Yet, their electronic structure still surprises with unexpected topological properties of the valence bands. In this joint theoretical and experimental ... More
The Grism Lens-Amplified Survey from Space (GLASS). I. Survey overview and first data releaseSep 01 2015Sep 04 2015We give an overview of the Grism Lens Amplified Survey from Space (GLASS), a large Hubble Space Telescope program aimed at obtaining grism spectroscopy of the fields of ten massive clusters of galaxies at redshift z=0.308-0.686, including the Hubble Frontier ... More
Conducting-angle-based percolation in the XY modelDec 17 2009We define a percolation problem on the basis of spin configurations of the two dimensional XY model. Neighboring spins belong to the same percolation cluster if their orientations differ less than a certain threshold called the conducting angle. The percolation ... More
Tricritical O(n) models in two dimensionsSep 27 2008We show that the exactly solved low-temperature branch of the two-dimensional O($n$) model is equivalent with an O($n$) model with vacancies and a different value of $n$. We present analytic results for several universal parameters of the latter model, ... More
Equivalent-neighbor percolation models in two dimensions: crossover between mean-field and short-range behaviorAug 17 2018We investigate the influence of the range of interactions in the two-dimensional bond percolation model, by means of Monte Carlo simulations. We locate the phase transitions for several interaction ranges, as expressed by the number $z$ of equivalent ... More
Supplementary material for: Adaptive Observers and Parameter Estimation for a Class of Systems Nonlinear in the ParametersApr 15 2013Apr 16 2013This supplement illustrates application of adaptive observer design from (Tyukin et al, 2013) for systems which are not uniquely identifiable. It also provides an example of adaptive observer design for a magnetic bearings benchmark system (Lin, Knospe, ... More
Homological Pisot Substitutions and Exact RegularityJan 12 2010Jul 06 2018We consider one-dimensional substitution tiling spaces where the dilatation (stretching factor) is a degree d Pisot number, and where the first rational Cech cohomology is d-dimensional. We construct examples of such "homological Pisot" substitutions ... More
Spin Seebeck and Spin Nernst Effects of Magnons in Noncollinear Antiferromagnetic InsulatorsMar 28 2019Our joint theoretical and computer experimental study of heat-to-spin conversion reveals that noncollinear antiferromagnetic insulators are promising materials for generating magnon spin currents upon application of a temperature gradient: they exhibit ... More
Medium-range interactions and crossover to classical critical behaviorJul 03 1996We study the crossover from Ising-like to classical critical behavior as a function of the range R of interactions. The power-law dependence on R of several critical amplitudes is calculated from renormalization theory. The results confirm the predictions ... More
A general realization theorem for matrix-valued Herglotz-Nevanlinna functionsOct 21 2005New special types of stationary conservative impedance and scattering systems, the so-called non-canonical systems, involving triplets of Hilbert spaces and projection operators, are considered. It is established that every matrix-valued Herglotz-Nevanlinna ... More
Emergent O(n) Symmetry in a series of three-dimensional Potts ModelsAug 19 2015Aug 29 2016We study the q-state Potts model on the simple cubic lattice with ferromagnetic interactions in one lattice direction, and antiferromagnetic interactions in the two other directions. As the temperature T decreases, the system undergoes a second-order ... More
Percolation in the canonical ensembleOct 12 2012Jan 01 2013We study the bond percolation problem under the constraint that the total number of occupied bonds is fixed, so that the canonical ensemble applies. We show via an analytical approach that at criticality, the constraint can induce new finite-size corrections ... More
Percolation transitions in two dimensionsJan 10 2009We investigate bond- and site-percolation models on several two-dimensional lattices numerically, by means of transfer-matrix calculations and Monte Carlo simulations. The lattices include the square, triangular, honeycomb kagome and diced lattices with ... More
Interparticle torques suppress motility-induced phase separation for rodlike particlesApr 02 2019To study the role of torque in motility-induced phase separation (MIPS), we simulate a system of self-propelled particles whose shape varies smoothly from isotropic (disks/spheres) to weakly elongated (rods). We construct the phase diagrams of 2D active ... More
Western Europe is warming much faster than expectedJun 04 2008Jun 06 2008The warming trend of the last decades is now so strong that it is discernible in local temperature observations. This opens the possibility to compare the trend to the warming predicted by comprehensive climate models (GCMs), which up to now could not ... More
Notes on the roots of Steiner polynomialsMar 13 2007We study the location and the size of the roots of Steiner polynomials of convex bodies in the Minkowski relative geometry. Based on a problem of Teissier on the intersection numbers of Cartier divisors of compact algebraic varieties it was conjectured ... More
Limit Cycle Bifurcations in a Quartic Ecological ModelFeb 16 2009In this paper we complete the global qualitative analysis of a quartic ecological model. In particular, studying global bifurcations of singular points and limit cycles, we prove that the corresponding dynamical system has at most two limit cycles.
Spin polarization of the L-gap surface states on Au(111)May 22 2003The electron spin polarization (ESP) of the L-gap surface states on Au(111) is investigated theoretically by means of first-principles electronic-structure and photoemission calculations. The surface states show a large spin-orbit induced in-plane ESP ... More
Calibration of weak-lensing shear in the Kilo-Degree SurveyJun 16 2016Jan 20 2017We describe and test the pipeline used to measure the weak lensing shear signal from the Kilo Degree Survey (KiDS). It includes a novel method of `self-calibration' that partially corrects for the effect of noise bias. We also discuss the `weight bias' ... More
The galaxy-subhalo connection in low-redshift galaxy clusters from weak gravitational lensingJun 19 2017May 16 2018We measure the gravitational lensing signal around satellite galaxies in a sample of galaxy clusters at $z<0.15$ by combining high-quality imaging data from the Canada-France-Hawaii Telescope with a large sample of spectroscopically-confirmed cluster ... More
A Unifying Framework for Strong Structural ControllabilityMar 08 2019This paper deals with strong structural controllability of linear systems. In contrast to existing work, the structured systems studied in this paper have a so-called zero/nonzero/arbitrary structure, which means that some of the entries are equal to ... More
Proofs of two conjectures on ternary weakly regular bent functionsMar 19 2008We study ternary monomial functions of the form $f(x)=\Tr_n(ax^d)$, where $x\in \Ff_{3^n}$ and $\Tr_n: \Ff_{3^n}\to \Ff_3$ is the absolute trace function. Using a lemma of Hou \cite{hou}, Stickelberger's theorem on Gauss sums, and certain ternary weight ... More
Geometric properties of two-dimensional O(n) loop configurationsAug 25 2006We study the fractal geometry of O($n$) loop configurations in two dimensions by means of scaling and a Monte Carlo method, and compare the results with predictions based on the Coulomb gas technique. The Monte Carlo algorithm is applicable to models ... More
Dependence of GAMA galaxy halo masses on the cosmic web environment from 100 square degrees of KiDS weak lensing dataApr 25 2016Galaxies and their dark matter haloes are part of a complex network of mass structures, collectively called the cosmic web. Using the tidal tensor prescription these structures can be classified into four cosmic environments: voids, sheets, filaments ... More
An Empirical Study of Intel Xeon PhiOct 22 2013Dec 20 2013With at least 50 cores, Intel Xeon Phi is a true many-core architecture. Featuring fairly powerful cores, two cache levels, and very fast interconnections, the Xeon Phi can get a theoretical peak of 1000 GFLOPs and over 240 GB/s. These numbers, as well ... More
On the observability of individual Population III stars and their stellar-mass black hole accretion disks through cluster caustic transitsMar 13 2019Recent near-IR power-spectra and panchromatic Extragalactic Background Light measurements provide upper limits on the near-IR surface brightness (SB>31 mag/arcsec^2) that may come from Pop III stars and accretion disks around resulting stellar-mass black ... More
Electrical transport through carbon nanotube junctions created by mechanical manipulationSep 05 2000Using an atomic force microscope we have created nanotube junctions such as buckles and crossings within individual single-wall metallic carbon nanotubes connected to metallic electrodes. The electronic transport properties of these manipulated structures ... More
Monte Carlo investigations of phase transitions: status and perspectivesAug 19 1999Using the concept of finite-size scaling, Monte Carlo calculations of various models have become a very useful tool for the study of critical phenomena, with the system linear dimension as a variable. As an example, several recent studies of Ising models ... More
The impact of high spatial frequency atmospheric distortions on weak lensing measurementsOct 21 2011Dec 02 2011High precision cosmology with weak gravitational lensing requires a precise measure of the Point Spread Function across the imaging data where the accuracy to which high spatial frequency variation can be modelled is limited by the stellar number density ... More
Phase transitions in self-dual generalizations of the Baxter-Wu modelSep 05 2009We study two types of generalized Baxter-Wu models, by means of transfer-matrix and Monte Carlo techniques. The first generalization allows for different couplings in the up- and down triangles, and the second generalization is to a $q$-state spin model ... More
Short-range correlations in percolation at criticalityJun 01 2014Feb 02 2015We derive the critical nearest-neighbor connectivity $g_n$ as $3/4$, $3(7-9p_c^{tri})/[4(5-4p_c^{tri})]$, and $3(2+7p_c^{tri})/[4(5-p_c^{tri})]$ for bond percolation on the square, honeycomb and triangular lattice respectively, where $p_c^{tri}=2\sin(\pi/18)$ ... More
The circumgalactic medium in Lyman-alpha: a new constraint on galactic outflow modelsJan 13 2019Galactic outflows are critical to our understanding of galaxy formation and evolution. However the details of the underlying feedback process remain unclear. We compare Ly$\alpha$ observations of the circumgalactic medium (CGM) of Lyman Break Galaxies ... More
The LyAlpha Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum LeakageJan 23 2015We present new Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet (far-UV) spectroscopy and Keck Echellete optical spectroscopy of 11 ultraluminous infrared galaxies (ULIRGs), a rare population of local galaxies experiencing massive gas ... More
The stellar-to-halo mass relation of GAMA galaxies from 100 square degrees of KiDS weak lensing dataJan 25 2016Apr 21 2017We study the stellar-to-halo mass relation of central galaxies in the range 9.7<log_10(M_*/h^-2 M_sun)<11.7 and z<0.4, obtained from a combined analysis of the Kilo Degree Survey (KiDS) and the Galaxy And Mass Assembly (GAMA) survey. We use ~100 deg^2 ... More
Dynamical Heterogeneities and Cooperative Motion in Smectic Liquid CrystalsJun 17 2009Using simulations of hard rods in smectic-A states, we find non-gaussian diffusion and heterogeneous dynamics due to the equilibrium periodic smectic density profiles, which give rise to permanent barriers for layer-to-layer diffusion. This relaxation ... More
Pushing the glass transition towards random close packing using self-propelled hard spheresJun 15 2013Oct 25 2013Although the concept of random close packing with an almost universal packing fraction of ~ 0.64 for hard spheres was introduced more than half a century ago, there are still ongoing debates. The main difficulty in searching the densest packing is that ... More
Near-infrared observations of water-ice in OH/IR starsJan 27 2006A search for the near-infrared water-ice absorption band was made in a number of very red OH/IR stars which are known to exhibit the 10um silicate absorption. As a by-product, accurate positions of these highly reddened objects are obtained. We derived ... More
Steiner polynomials via ultra-logconcave sequencesDec 20 2011We investigate structural properties of the cone of roots of relative Steiner polynomials of convex bodies. We prove that they are closed, monotonous with respect to the dimension, and that they cover the whole upper half-plane, except the positive real ... More
Bisimulation Relations Between Automata, Stochastic Differential Equations and Petri NetsMar 25 2010Two formal stochastic models are said to be bisimilar if their solutions as a stochastic process are probabilistically equivalent. Bisimilarity between two stochastic model formalisms means that the strengths of one stochastic model formalism can be used ... More
Acoustic and Textual Data Augmentation for Improved ASR of Code-Switching SpeechJul 28 2018In this paper, we describe several techniques for improving the acoustic and language model of an automatic speech recognition (ASR) system operating on code-switching (CS) speech. We focus on the recognition of Frisian-Dutch radio broadcasts where one ... More
Local Axisymmetric Diffusive Stability of Weakly-Magnetized, Differentially-Rotating, Stratified FluidsFeb 06 2004We study the local stability of stratified, differentially-rotating fluids to axisymmetric perturbations in the presence of a weak magnetic field and of finite resistivity, viscosity and heat conductivity. This is a generalization of the Goldreich-Schubert-Fricke ... More
On extensions of Minkowski's theorem on successive minimaMay 20 2014Minkowski's 2nd theorem in the Geometry of Numbers provides optimal upper and lower bounds for the volume of a $o$-symmetric convex body in terms of its successive minima. In this paper we study extensions of this theorem from two different points of ... More
Tuning independently Fermi energy and spin splitting in Rashba systems: Ternary surface alloys on Ag(111)May 07 2010By detailed first-principles calculations we show that the Fermi energy and the Rashba splitting in disordered ternary surface alloys (BiPbSb)/Ag(111) can be independently tuned by choosing the concentrations of Bi and Pb. The findings are explained by ... More
Code-Switching Detection with Data-Augmented Acoustic and Language ModelsJul 28 2018In this paper, we investigate the code-switching detection performance of a code-switching (CS) automatic speech recognition (ASR) system with data-augmented acoustic and language models. We focus on the recognition of Frisian-Dutch radio broadcasts where ... More
Interacting Multiple Model-Feedback Particle Filter for Stochastic Hybrid SystemsMay 26 2013In this paper, a novel feedback control-based particle filter algorithm for the continuous-time stochastic hybrid system estimation problem is presented. This particle filter is referred to as the interacting multiple model-feedback particle filter (IMM-FPF), ... More
Polydispersity stabilizes Biaxial Nematic Liquid CrystalsJun 26 2011Aug 17 2011Inspired by the observations of a remarkably stable biaxial nematic phase [E.v.d. Pol et al., Phys. Rev. Lett. 103, 258301 (2009)], we investigate the effect of size polydispersity on the phase behavior of a suspension of boardlike particles. By means ... More
Involvement of Surfactant Protein D in Ebola Virus Infection Enhancement via Glycoprotein InteractionJan 09 2019Since the largest 2014-2016 Ebola virus disease outbreak in West Africa, understanding of Ebola virus infection has improved, notably the involvement of innate immune mediators. Amongst them, collectins are important players in the antiviral innate immune ... More
Calibration of colour gradient bias in shear measurement using HST/CANDELS dataAug 21 2017Apr 19 2018Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point-spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity ... More
Out-of-equilibrium processes in suspensions of oppositely charged colloids: liquid-to-crystal nucleation and gel formationJul 13 2009We study the kinetics of the liquid-to-crystal transformation and of gel formation in colloidal suspensions of oppositely charged particles. We analyse, by means of both computer simulations and experiments, the evolution of a fluid quenched to a state ... More