Results for "Mattias Beck"

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Sub-cycle measurement of intensity correlations in the Terahertz rangeDec 07 2015Dec 16 2015The Terahertz frequency range bears intriguing opportunities, beyond very advanced applications in spectroscopy and matter control. Peculiar quantum phenomena are predicted to lead to light emission by non-trivial mechanisms. Typically, such emission ... More
Quantum Cascade Laser Frequency CombsOct 30 2015It was recently demonstrated that broadband quantum cascade lasers can operate as frequency combs. As such, they operate under direct electrical pumping at both mid-infrared and THz frequencies, making them very attractive for dual-comb spectroscopy. ... More
THz ultrastrong light-matter couplingNov 28 2016Cavity photon resonators with ultrastrong light-matter interactions are attracting interest both in semiconductor and superconducting systems displaying the capability to manipulate the cavity quantum electrodynamic ground state with controllable physical ... More
Coexisting frequency combs spaced by an octave in a monolithic quantum cascade laserOct 24 2018Quantum cascade lasers are proving to be instrumental in the development of compact frequency comb sources at mid-infrared and terahertz frequencies. Here we demonstrate a heterogeneous terahertz quantum cascade laser with two active regions spaced exactly ... More
Magneto-transport controlled by Landau polariton statesMay 02 2018Oct 17 2018Hybrid excitations, called polaritons, emerge in systems with strong light-matter coupling. Usually, they dominate the linear and nonlinear optical properties with applications in quantum optics. Here, we show the crucial role of the electronic component ... More
Pulses from a mid-infrared quantum cascade laser frequency comb using an external compressorMay 14 2019A Martinez-type stretcher-compressor is used to modify the spectral phases of a high-power (~1 W) QCL comb emitted at 8.2 {\mu}m with more than 100 cm-1 spectral bandwidth. Using this scheme, we demonstrate a compression of the QCL output from a 134 ps ... More
Birational geometry of moduli of curves with an $S_3$-coverMay 09 2019We consider the space $\mathcal R_{g,S_3}^{S_3}$ of curves with a connected $S_3$-cover, proving that for any odd genus $g\geq 13$ this moduli is of general type. Furthermore we develop a set of tools that are essential in approaching the case of $G$-covers ... More
Moduli of $G$-covers of curves: geometry and singularitiesMay 07 2019In a recent paper Chiodo and Farkas described the singular locus and the locus of non-canonical singularities of the moduli space of level curves. In this work we generalize their results to the moduli space $\overline{\mathcal R}_{g,G}$ of curves with ... More
A preconditioning strategy for linear systems arising from nonsymmetric schemes in isogeometric analysisMay 11 2017In the context of isogeometric analysis, we consider two discretization approaches that make the resulting stiffness matrix nonsymmetric even if the differential operator is self-adjoint. These are the collocation method and the recently-developed weighted ... More
Isomorphisms between complements of projective plane curvesFeb 17 2019In this article, we study isomorphisms between complements of irreducible curves in the projective plane $\mathbb{P}^2$, over an arbitrary algebraically closed field. Of particular interest are rational unicuspidal curves. We prove that if there exists ... More
A sound nebula: the origin of the Solar System in the field of a standing sound waveMar 15 2016According to the planetary origin conceptual model proposed in this paper, the protosun centre of the pre-solar nebula exploded, resulting in a shock wave that passed through it and then returned to the centre, generating a new explosion and shock wave. ... More
A comparison between pretriangulated $\mbox{A}_{\infty}$-categories and $\infty$-Stable categoriesSep 02 2016In this paper we will prove that the $\mbox{A}_{\infty}$-nerve of two quasi-equivalent $\mbox{A}_{\infty}$-categories are weak-equivalent in the Joyal model structure, a consequence of this fact is that the $\mbox{A}_{\infty}$-nerve of a pretriangulated ... More
A note on the universality of Hurwitz-Lerch zeta functionsDec 02 2016In this note we show that the Lerch zeta function $L(\lambda,\alpha,s)$ is strongly universal when $\lambda$ is irrational and $\alpha$ is rational, and for any $\lambda$ when $\alpha$ is irrational algebraic. This settles in the positive the conjecture ... More
Expanding solitons to the Hermitian curvature flow on complex Lie groupsOct 11 2018We investigate the algebraic structure of complex Lie groups equipped with left-invariant metrics which are expanding semi-algebraic solitons to the Hermitian curvature flow (HCF). We show that the Lie algebras of such Lie groups decompose in the semidirect ... More
Surgery and dualityMay 01 1999Surgery, as developed by Browder, Kervaire, Milnor, Novikov, Sullivan, Wall and others is a method for comparing homotopy types of topological spaces with diffeomorphism or homeomorphism types of manifolds of dimension >= 5. In this paper, a modification ... More
Invariant construction of solutions to Einstein`s field equations - LRS perfect fluids IDec 05 1996The properties of some locally rotationally symmetric (LRS) perfect fluid space-times are examined in order to demonstrate the usage of the description of geometries in terms of the Riemann tensor and a finite number of its covariant derivatives for finding ... More
On the space of metrics with invertible Dirac operatorMar 01 2006On a compact spin manifold we study the space of Riemannian metrics for which the Dirac operator is invertible. The first main result is a surgery theorem stating that such a metric can be extended over the trace of a surgery of codimension at least three. ... More
Degenerations of amoebae and Berkovich spacesJun 05 2014Apr 07 2015We prove a continuity result for the fibers of the Berkovich analytification of a complex algebraic variety with respect to the the maximum of the Archimedean norm and the trivial norm. As a consequence, we obtain generalizations of a result of Mikhalkin ... More
Prescribing eigenvalues of the Dirac operatorNov 11 2003Aug 05 2005In this note we show that every compact spin manifold of dimension $\geq 3$ can be given a Riemannian metric for which a finite part of the spectrum of the Dirac operator consists of arbitrarily prescribed eigenvalues with multiplicity 1.
On Bohr's equivalence theoremJan 20 2016Jan 21 2016In this note we show a converse of Bohr's equivalence theorem.
The Spitzer Data Fusion: Contents, Construction and Applications to Galaxy Evolution StudiesApr 08 2016Jun 21 2016We present the Spitzer Data Fusion, a database incorporating far-ultraviolet to far-infrared flux measurements as well as photometric and spectroscopic redshifts for 4.4 million IRAC-selected sources detected over 8 extragalactic fields covering 65 deg$^2$ ... More
Empirical Bayesian Learning in AR Graphical ModelsJul 08 2019We address the problem of learning graphical models which correspond to high dimensional autoregressive stationary stochastic processes. A graphical model describes the conditional dependence relations among the components of a stochastic process and ... More
The Forward Euler Scheme for Nonconvex Lipschitz Differential Inclusions Converges with Rate OneJan 30 2009In a previous paper it was shown that the Forward Euler method applied to differential inclusions where the right-hand side is a Lipschitz continuous set-valued function with uniformly bounded, compact values, converges with rate one. The convergence, ... More
POSSIS: predicting spectra, light curves and polarization for multi-dimensional models of supernovae and kilonovaeJun 10 2019We present POSSIS, a time-dependent three-dimensional Monte Carlo code for modelling radiation transport in supernovae and kilonovae. The code incorporates wavelength- and time-dependent opacities and predicts viewing-angle dependent spectra, light curves ... More
Existence and extinction in finite time for Stratonovich gradient noise porous media equationsNov 26 2018We study existence and uniqueness of distributional solutions to the stochastic partial differential equation $dX - ( \nu \Delta X + \Delta \psi (X) ) dt = \sum_{i=1}^N \langle b_i, \nabla X \rangle \circ d\beta_i$ in $]0,T[ \times \mathcal{O}$, with ... More
Expanding solitons to the Hermitian curvature flow on complex Lie groupsOct 11 2018Mar 05 2019We investigate the algebraic structure of complex Lie groups equipped with left-invariant metrics which are expanding semi-algebraic solitons to the Hermitian curvature flow (HCF). We show that the Lie algebras of such Lie groups decompose in the semidirect ... More
Signatures of Many-Particle InterferenceAug 22 2019This Tutorial will introduce the mathematical framework for describing systems of identical particles, and explain the notion of indistinguishability. We will then focus our attention on dynamical systems of free particles and formally introduce the concept ... More
Distributed Kalman Filtering under Model UncertaintyJul 13 2019We study the problem of distributed Kalman filtering for sensor networks in the presence of model uncertainty. More precisely, we assume that the actual state-space model belongs to a ball, in the Kullback-Leibler topology, about the nominal state-space ... More
Dirac eigenvalues for generic metrics on three-manifoldsApr 18 2002Jul 03 2013We show that for generic Riemannian metrics on a closed spin manifold of dimension three the Dirac operator has only simple eigenvalues.
InGaAs/AlInGaAs THz Quantum Cascade Lasers operating up to 195 K in strong magnetic fieldNov 06 2014Feb 20 2015Terahertz quantum cascade lasers based on InGaAs wells and quaternary AlInGaAs barriers were measured in magnetic field. This study was carried out on a four quantum well active region design with photon energy of 14.3 meV processed both with Au and Cu ... More
Octave-spanning semiconductor laserJul 11 2014We present here a semiconductor injection laser operating in continuous wave with an emission covering more than one octave in frequency, and displaying homogeneous power distribution among the lasing modes. The gain medium is based on a heterogeneous ... More
Room temperature terahertz polariton emitterJan 09 2012The strong-coupling regime between an electronic transition and the photonic mode of a optical resonator manifests itself in the lifting of the degeneracy between the two modes and the creation of two polariton states with mixed optical and electronic ... More
Evidence of Linear Chirp in Mid-Infrared Quantum Cascade LasersApr 11 2018We measure the inter-modal phase relation of a quantum cascade laser frequency comb operating at 8 um using a coherent beatnote spectroscopy. We find these phases to be reproducible after cycling the power of the device, and to be smoothly varying with ... More
Coupled-waveguides for dispersion compensation in semiconductor lasersNov 24 2017The generation of optical frequency combs via direct electrical pumping of semiconductor lasers is an attractive alternative to the well-established mode-locked laser sources in terms of compactness, robustness and integrability. However, the high chromatic ... More
Galactic and extragalactic magnetic fieldsDec 19 2000The current state of research of the Galactic magnetic field is reviewed critically. The average (equipartition) strength of the total field derived from radio synchrotron data is 6 +/- 2 muG locally and about 10 +/- 3 muG at 3 kpc Galactic radius. These ... More
Magnetic Visions: Mapping Cosmic Magnetism with LOFAR and SKAApr 29 2008The origin of magnetic fields in the Universe is an open problem in astrophysics and fundamental physics. "Cosmic Magnetism" has been accepted as Key Science Project both for the Low Frequency Array (LOFAR, under construction) and the planned Square Kilometre ... More
Determination of the E2/M1 Ratio in the γN \to Δ(1232) Transition from a Simultaneous Measurement of p(\vecγ,p)π^0 and p(\vecγ,π^+)nAug 26 1999Tagged linearly polarized photons have been used at the Mainz Microtron MAMI for simultaneous measurements of the p(\vec{\gamma},p)\pi^0 and p(\vec{\gamma},\pi^+)n reaction channels to study the \gamma N \to \Delta(1232) transition. The energy dependence ... More
Magnetic fields in nearby galaxies: prospects with future radio telescopesSep 01 2009The origin of magnetic fields in the Universe is an open problem in astrophysics and fundamental physics. Our present-day knowledge is limited to regions of strong magnetic fields and to star-forming disks of galaxies. Low-energy electrons emitting at ... More
Galactic Dynamos and Galactic WindsNov 29 2007Apr 24 2008Spiral galaxies host dynamically important magnetic fields which can affect gas flows in the disks and halos. Total magnetic fields in spiral galaxies are strongest (up to 30 \muG) in the spiral arms where they are mostly turbulent or tangled. Polarized ... More
Crystal structure of level zero extremal weight modulesMay 09 2002Dec 20 2002We consider the crystal structure of the level zero extremal weight modules $V(\lambda)$ using the crystal base of the quantum affine algebra constructed by Beck, Chari and Pressley. This approach yields an explicit form for the U^- extremal weight vectors ... More
Estimating grouped data models with a binary dependent variable and fixed effect via logit vs OLS: the impact of dropped unitsOct 26 2018This letter deals with a very simple issue: if we have grouped data with a binary dependent variable and want to include fixed effects (group specific intercepts) in the specification, is Ordinary Least Squares (OLS) in any way superior to a logit form ... More
Boundary regularity for elliptic systems under a natural growth conditionFeb 09 2010Jul 28 2010We consider weak solutions $u \in u_0 + W^{1,2}_0(\Omega,R^N) \cap L^{\infty}(\Omega,R^N)$ of second order nonlinear elliptic systems of the type $- div a (\cdot, u, Du) = b(\cdot,u,Du)$ in $\Omega$ with an inhomogeneity satisfying a natural growth condition. ... More
Calabi-Yau orbifolds over Hitchin basesJul 13 2018Any irreducible Dynkin diagram $\Delta$ is obtained from an irreducible Dynkin diagram $\Delta_h$ of type $\mathrm{ADE}$ by folding via graph automorphisms. For any simple complex Lie group $G$ with Dynkin diagram $\Delta$ and compact Riemann surface ... More
The Role of Magnetic Fields in Spiral GalaxiesDec 12 2002Interstellar magnetic fields are strong: up to 25 muG in spiral arms and 40 muG in nuclear regions. In the spiral galaxy NGC 6946 the average magnetic energy density exceeds that of the thermal gas. Magnetic fields control the evolution of dense clouds ... More
Magnetism in the spiral galaxy NGC 6946: magnetic arms, depolarization rings, dynamo modes and helical fieldsMay 29 2007Jun 05 2007The spiral galaxy NGC 6946 was observed in total intensity and linear polarization in five radio bands between 3cm and 21cm. At the inner edge of the inner gas spiral arm the ordered magnetic field is only mildly compressed and turns smoothly, to become ... More
Molecular structures and clustering effects in reactions induced by light nucleiFeb 26 2014$\alpha$-clustering study since the pioneering discovery of $^{12}$C+$^{12}$C molecular resonances half a century ago. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains ... More
Clustering effects induced by light nucleiMar 05 2013Mar 06 2013Since the pioneering discovery, half a century ago, of 12C+12C molecular resonances, a great deal of research work has been undertaken in theSince the pioneering discovery, half a century ago, of 12C+12C molecular resonances, a great deal of research ... More
Testing axion physics in a Josephson junction environmentOct 26 2011Nov 17 2011We suggest that experiments based on Josephson junctions, SQUIDS, and coupled Josephson qubits can be used to construct a resonant environment for dark matter axions. We propose experimental setups in which axionic interaction strengths in a Josephson ... More
Nuclear alpha-clustering, superdeformation, and molecular resonancesJan 06 2004Nuclear alpha-clustering has been the subject of intense study since the advent of heavy-ion accelerators. Looking back for more than 40 years we are able today to see the connection between quasimolecular resonances in heavy-ion collisions and extremely ... More
Molecular resonance phenomena and alpha-clustering: recent progress and perspectivesJan 06 2004The connection between molecular resonance phenomena in light heavy-ion collisions, alpha-clustering and extremely deformed states in light $\alpha$-like nuclei is discussed. For example, the superdeformed bands recently discovered in light N=Z nuclei ... More
Generalized statistical mechanics of cosmic raysJan 20 2003We consider a generalized statistical mechanics model for the creation process of cosmic rays which takes into account local temperature fluctuations. This model yields Tsallis statistics for the cosmic ray spectrum. It predicts an entropic index q given ... More
Spatio-temporal Chaos and Vacuum Fluctuations of Quantized FieldsJul 09 2002We consider deterministic chaotic models of vacuum fluctuations on a small (quantum gravity) scale. As a suitable small-scale dynamics, nonlinear versions of strings, so-called `chaotic strings' are introduced. These can be used to provide the `noise' ... More
Nonextensive methods in turbulence and particle physicsOct 03 2001We describe some recent applications of Tsallis statistics in fully developed hydrodynamic turbulence and high energy physics. For many of these applications nonextensive properties arise from spatial fluctuations of the temperature or the energy dissipation ... More
Non-additivity of Tsallis entropies and fluctuations of temperatureMay 18 2001We show that the non-additivity relation of the Tsallis entropies in nonextensive statistical mechanics has a simple physical interpretation for systems with fluctuating temperature or fluctuating energy dissipation rate. We also show that there is a ... More
Competition between quasi-molecular resonances and fusion-fission in light dinuclear systemsAug 21 1998The results presented in this paper clearly suggest that a coherent framework may exist which connects the topics of heavy-ion molecular resonances, hyperdeformation effects, and fission shape isomerism. New data on particle-particle-$\gamma$ triple coincidences ... More
Axion physics in a Josephson junction environmentAug 12 2010Nov 23 2011We show that recent experiments based on Josephson junctions, SQUIDS, and coupled Josephson qubits have a cosmological interpretation in terms of axionic dark matter physics, in the sense that they allow for analogue simulation of early-universe axion ... More
Alpha-Cluster States Populated in 24Mg+12CAug 18 2008Charged particle and gamma decays in light alpha-like nuclei are investigated for 24Mg+12C. Various theoretical predictions for the occurence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are presented. The ... More
Superstatistics in hydrodynamic turbulenceMar 15 2003Superstatistics is a `statistics of a statistics' relevant for driven nonequilibrium systems with fluctuating intensive parameters. It contains Tsallis statistics as a special case. We show that the probability density functions of velocity differences ... More
Chaotic strings and standard model parametersMay 16 2001We introduce so-called chaotic strings (coupled 1-dimensional noise strings underlying the Parisi-Wu approach of stochastic quantization on a small scale) as a possible amendment of ordinary string theories. These strings are strongly self-interacting ... More
Non-extensive statistical mechanics approach to fully developed hydrodynamic turbulenceMay 24 2000We apply non-extensive methods to the statistical analysis of fully developed turbulent flows. Probability density functions of velocity differences at distance r obtained by extremizing the Tsallis entropies coincide well with what is measured in turbulence ... More
Future Observations of Cosmic Magnetic Fields with the SKA and its PrecursorsNov 24 2011Aug 02 2012The origin of magnetic fields in the Universe is an open problem in astrophysics and fundamental physics. Polarization observations with the forthcoming large radio telescopes, especially the Square Kilometre Array (SKA), will open a new era in the observation ... More
Transfer/Breakup Channel Couplings in Sub-barrier Fusion ReactionsAug 31 2012Oct 22 2012With the recent availability of state-of-the-art radioactive ion beams, there has been a renew interest in the investigation of nuclear reactions with heavy ions near the Coulomb barrier. The role of inelastic and transfer channel couplings in fusion ... More
An uncombed inversion of multi-wavelength observations reproducing the Net Circular Polarization in a sunspots' penumbraOct 11 2010I derived a geometrical model of the penumbral magnetic field topology from an uncombed inversion setup that aimed at reproducing the NCP of simultaneous spectra in near-IR (1.56 mu) and VIS (630 nm) spectral lines. I inverted the spectra of five photospheric ... More
Recent developments in superstatisticsNov 26 2008Feb 15 2009We provide an overview on superstatistical techniques applied to complex systems with time scale separation. Three examples of recent applications are dealt with in somewhat more detail: the statistics of small-scale velocity differences in Lagrangian ... More
Superstatistical turbulence modelsJun 14 2005Recently there has been some progress in modeling the statistical properties of turbulent flows using simple superstatistical models. Here we briefly review the concept of superstatistics in turbulence. In particular, we discuss a superstatistical extension ... More
Superstatistics: Theory and ApplicationsMar 15 2003Superstatistics is a superposition of two different statistics relevant for driven nonequilibrium systems with a stationary state and intensive parameter fluctuations. It contains Tsallis statistics as a special case. After briefly summarizing some of ... More
Dynamical foundations of nonextensive statistical mechanicsMay 18 2001We construct classes of stochastic differential equations with fluctuating friction forces that generate a dynamics correctly described by Tsallis statistics and nonextensive statistical mechanics. These systems generalize the way in which ordinary Langevin ... More
Non-extensive statistical mechanics and particle spectra in elementary interactionsApr 25 2000We generalize Hagedorn's statistical theory of momentum spectra of particles produced in high-energy collisions using Tsallis' formalism of non-extensive statistical mechanics. Suitable non-extensive grand canonical partition functions are introduced ... More
A 3-D sunspot model derived from an inversion of spectropolarimetric observations and its implications for the penumbral heatingDec 19 2007I deduced a 3-D sunspot model that is in agreement with spectropolarimetric observations, to address the question of penumbral heating by the repetitive rise of flow channels. I performed inversions of data taken simultaneously in infrared and visible ... More
Dark energy, chaotic fields, and fundamental constantsFeb 10 2005To explain the currently observed accelerated expansion of the universe, a large number of different theoretical models are presently being discussed. In one way or another, all of these contain `new physics', though at different levels. The big question ... More
Combinatorial Reciprocity TheoremsJan 11 2012A common theme of enumerative combinatorics is formed by counting functions that are polynomials evaluated at positive integers. In this expository paper, we focus on four families of such counting functions connected to hyperplane arrangements, lattice ... More
Outermost apparent horizons diffeomorphic to unit normal bundlesJun 27 2016For $p \geq 1$, $q \geq 2$ with $n = p + q \leq 7$ and a compact, embedded submanifold $S \subset \mathbb R^p$ of dimension at most $p - 1$ we construct an $n$-dimensional asymptotically Euclidean Riemannian manifold with zero scalar curvature having ... More
Isogeometric preconditioners based on fast solvers for the Sylvester equationFeb 04 2016Jul 21 2016We consider large linear systems arising from the isogeometric discretization of the Poisson problem on a single-patch domain. The numerical solution of such systems is considered a challenging task, particularly when the degree of the splines employed ... More
Sparse plus Low rank Network Identification: A Nonparametric ApproachOct 10 2015Oct 09 2016Modeling and identification of high-dimensional stochastic processes is ubiquitous in many fields. In particular, there is a growing interest in modeling stochastic processes with simple and interpretable structures. In many applications, such as econometrics ... More
A Bayesian Approach to Sparse plus Low rank Network IdentificationMar 25 2015Sep 26 2015We consider the problem of modeling multivariate time series with parsimonious dynamical models which can be represented as sparse dynamic Bayesian networks with few latent nodes. This structure translates into a sparse plus low rank model. In this paper, ... More
AR Identification of Latent-variable Graphical ModelsApr 30 2014Dec 01 2014The paper proposes an identification procedure for autoregressive gaussian stationary stochastic processes wherein the manifest (or observed) variables are mostly related through a limited number of latent (or hidden) variables. The method exploits the ... More
Model Predictive Control meets robust Kalman filteringMar 15 2017Model Predictive Control (MPC) is the principal control technique used in industrial applications. Although it offers distinguishable qualities that make it ideal for industrial applications, it can be questioned its robustness regarding model uncertainties ... More
Production of W and Z bosons accompanied by jets at LHC startupSep 29 2008Oct 09 2008We report on potential for measurement of W and Z boson production accompanied by jets at the CMS experiment. Of particular interest are jet multiplicity and Pt distributions. The 10/pb to 100/pb datasets expected in the startup year of operation of LHC ... More
The effect of rotation on the thermal instability of stratified galactic atmospheres - II. The formation of High Velocity CloudsMar 14 2019Whether High Velocity Clouds (HVCs) can form by condensation of the hot ($T \sim 10^6 \, {\rm K}$) Galactic corona as a consequence of thermal instabilities has been controversial. Here we re-examine this problem and we suggest that rotation of the corona ... More
The motivic class of the classifying stack of the special orthogonal groupSep 26 2016Jul 05 2017We compute the class of the classifying stack of the special orthogonal group in the Grothendieck ring of stacks, and check that it is equal to the multiplicative inverse of the class of the group.
Convergence of p-adic pluricanonical measures to Lebesgue measures on skeleta in Berkovich spacesMay 07 2019Let $K$ be a non-archimedean local field, $X$ a smooth and proper $K$-scheme, and fix a pluricanonical form on $X$. For every finite extension $K'$ of $K$, the pluricanonical form induces a measure on the $K'$-analytic manifold $X(K')$. We prove that, ... More
Tree Ensembles with Rule Structured Horseshoe RegularizationFeb 16 2017Feb 15 2018We propose a new Bayesian model for flexible nonlinear regression and classification using tree ensembles. The model is based on the RuleFit approach in Friedman and Popescu (2008) where rules from decision trees and linear terms are used in a L1-regularized ... More
On the coupling of Model Predictive Control and Robust Kalman FilteringApr 17 2018Apr 20 2018Model Predictive Control (MPC) represents nowadays one of the main methods employed for process control in industry. Its strong suits comprise a simple algorithm based on a straightforward formulation and the flexibility to deal with constraints. On the ... More
Canonical heights for plane polynomial maps of small topological degreeFeb 01 2012Oct 24 2012We study canonical heights for plane polynomial mappings of small topological degree. In particular, we prove that for points of canonical height zero, the arithmetic degree is bounded by the topological degree and hence strictly smaller than the first ... More
Hermitian curvature flow on locally homogeneous complex surfacesJun 27 2019We study the Hermitian curvature flow of locally homogeneous non-K\"ahler metrics on compact complex surfaces. In particular, we characterize the long-time behaviour of the solutions to the flow. Finally, we compute the Gromov-Hausdorff limit of immortal ... More
Community structure and interaction dynamics through the lens of quotesApr 15 2016This is the first work investigating community structure and interaction dynamics through the lens of quotes in online discussion forums. We examine four forums of different size, language, and topic. Quote usage, which is surprisingly consistent over ... More
The Kato-Nakayama space as a transcendental root stackNov 12 2016We give a functorial description of the Kato-Nakayama space of a fine saturated log analytic space that is similar in spirit to the functorial description of root stacks. As a consequence we get a global description of the comparison map constructed in ... More
Infinite root stacks and quasi-coherent sheaves on logarithmic schemesOct 05 2014We define and study infinite root stacks of fine and saturated logarithmic schemes, a limit version of the root stacks introduced by Niels Borne and the second author. We show in particular that the infinite root stack determines the logarithmic structure, ... More
The motivic class of the classifying stack of the special orthogonal groupSep 26 2016We compute the class of the classifying stack of the special orthogonal group in the Grothendieck ring of stacks, and check that it is equal to the multiplicative inverse of the class of the group.
Sparse Control of Multiagent SystemsSep 23 2016In recent years, numerous studies have focused on the mathematical modeling of social dynamics, with self-organization, i.e., the autonomous pattern formation, as the main driving concept. Usually, first or second order models are employed to reproduce, ... More
Radiation damping in pulsed Gaussian beamsOct 05 2011We consider the effects of radiation damping on the electron dynamics in a Gaussian beam model of a laser field. For high intensities, i.e. with dimensionless intensity a0 \gg 1, it is found that the dynamics divide into three regimes. For low energy ... More
Identifying the Neutrino mass Ordering with INO and NOvAMar 15 2012Oct 24 2012The relatively large value of $\theta_{13}$ established recently by the Daya Bay reactor experiment opens the possibility to determine the neutrino mass ordering with experiments currently under construction. We investigate synergies between the NOvA ... More
Scalar Perturbations in Two-Temperature Cosmological PlasmasApr 11 2006We study the properties of density perturbations of a two-component plasma with a temperature difference on a homogeneous and isotropic background. For this purpose we extend the general relativistic gauge invariant covariant (GIC) perturbation theory ... More
Photon-Axion mixing in an inhomogeneous universeJul 24 2002May 28 2003We consider the dimming of photons from high redshift type 1a supernovae by mixing with a pseudoscalar axion field in the intergalactic medium. We model the electron density using a lognormal probability distribution and assume frozen in magnetic fields. ... More
Effective Neutrino Mixing and Oscillations in Dense MatterSep 06 2004Feb 18 2005We investigate the effective case of two-flavor neutrino oscillations in infinitely dense matter by using a perturbative approach. We begin by briefly summarizing the conditions for the three-flavor neutrino oscillation probabilities to take on the same ... More
Exact series solution to the two flavor neutrino oscillation problem in matterMay 05 2004Jul 26 2004In this paper, we present a real non-linear differential equation for the two flavor neutrino oscillation problem in matter with an arbitrary density profile. We also present an exact series solution to this non-linear differential equation. In addition, ... More
Magnetic fields in the early universe in the string approach to MHDApr 26 1999There is a reformulation of magnetohydrodynamics in which the fundamental dynamical quantities are the positions and velocities of the lines of magnetic flux in the plasma, which turn out to obey equations of motion very much like ideal strings. We use ... More
Regular Polynomial Endomorphisms of C^kMay 18 1998We study the dynamics of polynomial mappings f:C^k to C^k of degree at least 2 that extend continuously to projective space P^k. Our approach is to study the dynamics near the hyperplane at infinity and then making a descent to K --- the set of points ... More
Rotating matter in general relativity -- stationary state INov 14 1996Stationary rotating matter configurations in general relativity are considered. A formalism for general stationary space times is developed. Axisymmetric systems are discussed by the use of a nonholonomic and nonrigid frame in the three-space of the time-like ... More
A Spectrum Sharing Solution for the Efficient Use of mmWave Bands in 5G Cellular ScenariosAug 15 2018Regulators all around the world have started identifying the portions of the spectrum that will be used for the next generation of cellular networks. A band in the mmWave spectrum will be exploited to increase the available capacity. In response to the ... More