Results for "Thanja Lamberts"

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Tunneling Reaction Kinetics for the Hydrogen Abstraction Reaction H + H$_2$S -> H$_2$ + HS in the Interstellar MediumDec 06 2017The hydrogen abstraction reaction between H and H$_2$S, yielding HS and H$_2$ as products, has been studied within the framework of interstellar surface chemistry. High-temperature rate constants up to 2000 K are calculated in the gas phase and are in ... More
Influence of surface and bulk water ice on the reactivity of a water-forming reactionAug 18 2017On the surface of icy dust grains in the dense regions of the interstellar medium a rich chemistry can take place. Due to the low temperature, reactions that proceed via a barrier can only take place through tunneling. The reaction H + H$_2$O$_2$ $\rightarrow$ ... More
Atom Tunneling in the Water Formation Reaction H$_2$ + OH $\rightarrow$ H$_2$O + H on an Ice SurfaceAug 18 2017OH radicals play a key role as an intermediate in the water formation chemistry of the interstellar medium. For example the reaction of OH radicals with H$_2$ molecules is among the final steps in the astrochemical reaction network starting from O, O$_2$, ... More
Thermal H/D exchange in polar ice - deuteron scrambling in spaceFeb 12 2015We have investigated the thermally induced proton/deuteron exchange in mixed amorphous H$_2$O:D$_2$O ices by monitoring the change in intensity of characteristic vibrational bending modes of H$_2$O, HDO, and D$_2$O with time and as function of temperature. ... More
Quantum tunneling during interstellar surface-catalyzed formation of water: the reaction H + H$_2$O$_2$ $\rightarrow$ H$_2$O + OHNov 28 2016The final step of the water formation network on interstellar grain surfaces starting from the H + O$_2$ route is the reaction between H and H$_2$O$_2$. This reaction is known to have a high activation energy and therefore at low temperatures it can only ... More
Importance of tunneling in H-abstraction reactions by OH radicals: The case of CH4 + OH studied through isotope-substituted analogsDec 21 2016We present a combined experimental and theoretical study focussing on the quantum tunneling of atoms in the reaction between CH4 and OH. The importance of this reaction pathway is derived by investigating isotope substituted analogs. Quantitative reaction ... More
Low Temperature Surface Formation of NH3 and HNCO: hydrogenation of nitrogen atoms in CO-rich interstellar ice analoguesMay 25 2017Solid state astrochemical reaction pathways have the potential to link the formation of small nitrogen-bearing species, like NH3 and HNCO, and prebiotic molecules, specifically amino acids. To date, the chemical origin of such small nitrogen containing ... More
Formation of Acetaldehyde on CO-rich IcesApr 12 2019The radicals HCO and CH$_3$ on carbon monoxide ice surfaces were simulated using density functional theory. Their binding energy on amorphous CO ice shows broad distributions, with approximative average values of 500 K for HCO and 200 K for CH$_3$. If ... More
Experimental evidence for Glycolaldehyde and Ethylene Glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditionsMay 25 2017This study focuses on the formation of two molecules of astrobiological importance - glycolaldehyde (HC(O)CH2OH) and ethylene glycol (H2C(OH)CH2OH) - by surface hydrogenation of CO molecules. Our experiments aim at simulating the CO freeze-out stage in ... More
Efficient Surface Formation Route of Interstellar Hydroxylamine through NO Hydrogenation II: the multilayer regime in interstellar relevant icesMay 25 2017Hydroxylamine (NH2OH) is one of the potential precursors of complex pre-biotic species in space. Here we present a detailed experimental study of hydroxylamine formation through nitric oxide (NO) surface hydrogenation for astronomically relevant conditions. ... More
On the relevance of the H2 + O reaction pathway for the surface formation of interstellar water - A combined experimental and modeling studySep 10 2014The formation of interstellar water has been commonly accepted to occur on the surfaces of icy dust grains in dark molecular clouds at low temperatures (10-20 K), involving hydrogenation reactions of oxygen allotropes. As a result of the large abundances ... More
Spline approximations to conditional Archimedean copulaNov 15 2013We propose a flexible copula model to describe changes with a covariate in the dependence structure of (conditionally exchangeable) random variables. The starting point is a spline approximation to the generator of an Archimedean copula. Changes in the ... More
A remark on gradient estimates for spacelike mean curvature flow with boundary conditionsOct 07 2016We prove a gradient estimate for graphical spacelike mean curvature flow with a general Neumann boundary condition in dimension $n=2$. This then implies that the mean curvature flow exists for all time and converges to a translating solution.
M-Theory and Maximally Supersymmetric Gauge TheoriesMar 19 2012May 21 2012In this informal review for non-specalists we discuss the construction of maximally supersymmetric gauge theories that arise on the worldvolumes branes in String Theory and M-Theory. Particular focus is made on the relatively recent construction of M2-brane ... More
On the Computation of Certain Weighted ColimitsNov 16 2017The present paper gives computations of weighted pseudo-colimits of pseudo-functors on 1-categories valued in certain 2-categories, such as the 2-category of contravariant pseudo-functors on a 1-category. The main result is a generalization of the well-known ... More
Representation Embeddings of Cartesian TheoriesDec 08 2016Nov 07 2017A representation embedding between cartesian theories can be defined to be a functor between respective categories of models that preserves finitely-generated projective models and that preserves and reflects certain epimorphisms. This recalls standard ... More
Some problems with a Scotsman and a Russian: Caveats on Bayesian and hidden-Markov models (v2.3)Aug 18 2016This paper describes a number of fundamental and practical problems in the application of hidden-Markov models and Bayes when applied to cursive-script recognition. Several problems, however, will have an effect in other application areas. The most fundamental ... More
Caveats on Bayesian and hidden-Markov models (v2.6)Aug 18 2016Oct 28 2016This paper describes a number of fundamental and practical problems in the application of hidden-Markov models and Bayes when applied to cursive-script recognition. Several problems, however, will have an effect in other application areas. The most fundamental ... More
Probabilistic Models for the (sub)Tree(s) of LifeMar 11 2016Jul 08 2016The goal of these lectures is to review some mathematical aspects of random tree models used in evolutionary biology to model gene trees or species trees. We start with stochastic models of tree shapes (finite trees without edge lengths), culminating ... More
Incomplete determinantal processes: from random matrix to Poisson statisticsDec 02 2016We study linear statistics of a class of determinantal processes which interpolate between Poisson and GUE/Ginibre statistics in dimension 1 or 2. These processes are obtained by performing an independent Bernoulli percolation on the particle configuration ... More
Mesoscopic central limit theorem for the circular beta-ensembles and applicationsFeb 18 2019We give a simple proof of a central limit theorem for linear statistics of the Circular beta-ensembles which is valid at almost arbitrary mesoscopic scale and for functions of class C^3. As a consequence, using a coupling introduced by Valko and Virag, ... More
CLT for biorthogonal ensembles and related combinatorial identitiesNov 19 2015We study the fluctuations of certain biorthogonal ensembles for which the underlying family $\{P,Q\}$ satisfies a finite-term recurrence relation of the form $x P(x) = \mathbf{J}P(x)$. For polynomial linear statistics of such ensembles, we reformulate ... More
Representation Embeddings of Cartesian TheoriesDec 08 2016A representation embedding between cartesian theories can be defined to be a functor between respective categories of models that preserves indecomposable projective models and that preserves and reflects certain epimorphisms. This recalls standard definitions ... More
A large-scale field test on word-image classification in large historical document collections using a traditional and two deep-learning methodsApr 17 2019This technical report describes a practical field test on word-image classification in a very large collection of more than 300 diverse handwritten historical manuscripts, with 1.6 million unique labeled images and more than 11 million images used in ... More
The perpendicular Neumann problem for mean curvature flow with a timelike cone boundary conditionAug 16 2011Nov 23 2011This paper demonstrates existence for all time of mean curvature flow in Minkowski space with a perpendicular Neumann boundary condition, where the boundary manifold is a convex cone and the flowing manifold is initially spacelike. Using a blowdown argument, ... More
Mesoscopic fluctuations for unitary invariant ensemblesOct 13 2015Sep 11 2016Considering a determinantal point process on the real line, we establish a connection between the sine-kernel asymptotics for the correlation kernel and the CLT for mesoscopic linear statistics. This implies universality of mesoscopic fluctuations for ... More
The allelic partition for coalescent point processesApr 16 2008Feb 09 2009Assume that individuals alive at time $t$ in some population can be ranked in such a way that the coalescence times between consecutive individuals are i.i.d. The ranked sequence of these branches is called a coalescent point process. We have shown in ... More
Construction of Maximal Hypersurfaces with Boundary ConditionsAug 22 2014Oct 07 2016We construct maximal hypersurfaces with a Neumann boundary condition in Minkowski space via mean curvature flow. In doing this we give general conditions for long time existence of the flow with boundary conditions with assumptions on the curvature of ... More
Gamma-ray binaries : a bridge between Be stars and high energy astrophysicsOct 14 2014Advances in X-ray and gamma-ray astronomy have opened a new window on our universe and revealed a wide variety of binaries composed of a compact object and a Be star. In Be X-ray binaries, a neutron star accretes the Be disk and truncates it through tidal ... More
Theta-vexillary signed permutationsJul 23 2018Theta-vexillary signed permutations are elements in the hyperoctahedral group that index certain classes of degeneracy loci of type B and C. These permutations are described using triples of $s$-tuples of integers subject to specific conditions. The objective ... More
Random ultrametric trees and applicationsFeb 25 2017Ultrametric trees are trees whose leaves lie at the same distance from the root. They are used to model the genealogy of a population of particles co-existing at the same point in time. We show how the boundary of an ultrametric tree, like any compact ... More
The law of large numbers for the maximum of the characteristic polynomial of the Ginibre ensembleFeb 06 2019We compute the leading asymptotics of the logarithm of the absolute value of the characteristic polynomial, denoted \Psi_N, of the Ginibre ensemble as the dimension of the random matrix N tends to +\infty. The method relies on an upper-bound which follows ... More
Heterotic M2-branesJul 28 2015Aug 05 2015We construct the action for N M2-branes on $S^1/{Z}_2$. The resulting theory has a gauge anomaly but this can be cancelled if the two fixed point planes each support 8 chiral Fermions in the fundamental of U(N). Taking the low energy limit leads to the ... More
Flux and Freund-Rubin Superpotentials in M-theoryFeb 22 2005Apr 14 2005We discuss the effective action for weak G_2 compactifications of M-theory. The presence of fluxes acts as a source for the the axions and drives the Freund-Rubin parameter to zero. The result is a stable non-supersymmetric vacuum with a negative cosmological ... More
The M5-brane on K3 x T^2Dec 19 2007Jan 10 2008We discuss the low energy effective theory of an M5-brane wrapped on a smooth holomorphic four-cycle of K3 x T^2, including the special case of T^6. In particular we give the lowest order equations of motion and resolve a puzzle concerning the counting ... More
Lessons from M2's and Hopes for M5'sMar 07 2019In this talk we will review the construction of M2-brane SCFT's highlighting some novelties and the role of 3-algebras. Parts of our discussion will closely follow parts of arXiv:1203.3546. Next we will discuss M5-branes: the basics, the obstacles as ... More
Species abundance distributions in neutral models with immigration or mutation and general lifetimesSep 01 2010We consider a general, neutral, dynamical model of biodiversity. Individuals have i.i.d. lifetime durations, which are not necessarily exponentially distributed, and each individual gives birth independently at constant rate \lambda. We assume that types ... More
The branching process with logistic growthMay 12 2005In order to model random density-dependence in population dynamics, we construct the random analogue of the well-known logistic process in the branching process' framework. This density-dependence corresponds to intraspecific competition pressure, which ... More
The constant angle problem for mean curvature flow inside rotational toriJul 18 2012We flow a hypersurface in Euclidean space by mean curvature flow with a Neumann boundary condition, where the boundary manifold is any torus of revolution. If we impose the conditions that the initial manifold is compatible and does not contain the rotational ... More
The contour of splitting trees is a Lévy processApr 24 2007Feb 09 2009Splitting trees are those random trees where individuals give birth at constant rate during a lifetime with general distribution, to i.i.d. copies of themselves. The width process of a splitting tree is then a binary, homogeneous Crump--Mode--Jagers (CMJ) ... More
The genealogy of a sample from a binary branching processOct 05 2017At time 0, start a time-continuous binary branching process, where particles give birth to a single particle independently (at a possibly time-dependent rate) and die independently (at a possibly time-dependent and age-dependent rate). A particular case ... More
Flexible estimation in cure survival models using Bayesian P-splinesDec 09 2013May 14 2014In the analysis of survival data, it is usually assumed that any unit will experience the event of interest if it is observed for a sufficient long time. However, one can explicitly assume that an unknown proportion of the population under study will ... More
Conformal symmetries of gravity from asymptotic methods: further developmentsSep 16 2014Aug 10 2015In this thesis, the symmetry structure of gravitational theories at null infinity is studied further, in the case of pure gravity in four dimensions and also in the case of Einstein-Yang-Mills theory in $d$ dimensions with and without a cosmological constant. ... More
Modeling Multiple M2'sNov 09 2006Feb 21 2007We investigate the worldvolume theory that describes N coincident M2-branes ending on an M5 brane. We argue that the fields that describe the transverse spacetime coordinates take values in a non-associative algebra. We postulate a set of supersymmetry ... More
Steering of a Bosonic Mode with a Double Quantum DotFeb 13 2003We investigate the transport and coherence properties of a double quantum dot coupled to a single damped boson mode. Our numerically results reveal how the properties of the boson distribution can be steered by altering parameters of the electronic system ... More
Nonabelian (2,0) Tensor Multiplets and 3-algebrasJul 18 2010Aug 01 2010Using 3-algebras we obtain a nonabelian system of equations that furnish a representation of the (2,0)-supersymmetric tensor multiplet. The on-shell conditions are quite restrictive so that the system can be reduced to five-dimensional gauge theory along ... More
Heterotic p-branes from Massive Sigma ModelsMay 02 1996Jul 11 1996We explicitly construct massive (0,4) supersymmetric ADHM sigma models which have heterotic p-brane solitons as their conformal fixed points. These yield the familiar gauge 5-brane and a new 1-brane solution which preserve 1/2 and 1/4 of the spacetime ... More
Stability analysis of the Witten black hole (cigar soliton) under world-sheet RG flowMay 14 2012Sep 01 2012We analyze the stability of the Euclidean Witten black hole (the cigar soliton in mathematics literature) under first-order RG (Ricci) flow of the world-sheet sigma model. This analysis is from the target space point of view. We find that the Witten black ... More
Quantum Hall ferromagnetic phases in the Landau level N=0 of a graphene bilayerJan 14 2013In a Bernal-stacked graphene bilayer, an electronic state in Landau level $% N=0$ is described by its guiding-center index $X$ (in the Landau gauge) and by its valley, spin, and orbital indices $\xi =\pm K,\sigma =\pm 1,$ and $% n=0,1.$ When Coulomb interaction ... More
Relativistic simulations of long-lived reverse shocks in stratified ejecta: the origin of flares in GRB afterglowsFeb 14 2017Dec 05 2017The X-ray light curves of the early afterglow phase from gamma-ray bursts present a puzzling variability, including flares. The origin of these flares is still debated, and often associated with a late activity of the central engine. We discuss an alternative ... More
Radio Scintillation due to Discontinuities in the Interstellar Plasma DensityNov 18 1999We develop the theory of interstellar scintillation as caused by an irregular plasma having a power-law spatial density spectrum with a spectral exponent of 4 corresponding to a medium with abrupt changes in its density. An ``outer scale'' is included ... More
Quantum Resonances of Weakly Linked, Mesoscopic, Superconducting DotsMar 04 1994We examine quantum properties of mesoscopic, Josephson coupled superconducting dots, in the limit that charging effects and quantization of energy levels within the dots are negligible, but quasi-particle transmission into the weak link is not. We demonstrate ... More
The Stokes phenomenon in the confluence of the hypergeometric equation using Riccati equationJun 12 2007Nov 01 2007In this paper we study the confluence of two regular singular points of the hypergeometric equation into an irregular one. We study the consequence of the divergence of solutions at the irregular singular point for the unfolded system. Our study covers ... More
Estimates of the Quantum Fisher Information in the $S=1$ Anti-Ferromagnetic Heisenberg Spin Chain with Uniaxial AnisotropyOct 03 2018The quantum Fisher information is of considerable interest not only for quantum metrology but also because it is a useful entanglement measure for finite temperature mixed states. In particular, it estimates the degree to which multipartite entanglement ... More
Evolution of discrete populations and the canonical diffusion of adaptive dynamicsJan 26 2006Feb 28 2007The biological theory of adaptive dynamics proposes a description of the long-term evolution of a structured asexual population. It is based on the assumptions of large population, rare mutations and small mutation steps, that lead to a deterministic ... More
On the VLBI measurement of the Solar System accelerationOct 10 2013We propose new estimates of the secular aberration drift, mainly due to the rotation of the Solar System about the Galactic center, based on up-to-date VLBI observations and and improved method of outlier elimination. We fit degree-2 vector spherical ... More
Membranes on an OrbifoldApr 07 2008Apr 15 2008We harvest clues to aid with the interpretation of the recently discovered N=8 supersymmetric Chern-Simons theory with SO(4) gauge symmetry. The theory is argued to describe two membranes moving in the orbifold R8/Z2. At level k=1 and k=2, the classical ... More
Two Loop Renormalization of Massive (p,q) Supersymmetric Sigma ModelsOct 18 1995We calculate the beta-functions of the general massive (p,q) supersymmetric sigma model to two loop order using (1,0) superfields. The conditions for finiteness are discussed in relation to (p,q) supersymmetry. We also calculate the effective potential ... More
Perturbation Theory From Automorphic FormsJan 19 2010May 12 2010Using our previous construction of Eisenstein-like automorphic forms we derive formulae for the perturbative and non-perturbative parts for any group and representation. The result is written in terms of the weights of the representation and the derivation ... More
D-brane Bound States and the Generalised ADHM ConstructionJul 17 1997Jan 08 1998We discuss the sigma model description of a D-string bound to k D-fivebranes in type I string theory. The effective theory is an (0,4) supersymmetric hyper-Kahler with torsion sigma model on the moduli space of Sp(k) instantons on R^4. Upon toroidal compactification ... More
Basic concepts in single-molecule electronicsJan 02 2016This tutorial outlines the basic theoretical concepts and tools which underpin the fundamentals of phase-coherent electron transport through single molecules. The key quantity of interest is the transmission coefficient T(E), which yields the electrical ... More
Search for the primordial gravitational waves with Very Long Baseline InterferometryMar 30 2016Some models of the expanding Universe predict that the astrometric proper motion of distant radio sources embedded in space-time are non-zero as the radial distance from observer to the source grows. Systematic proper motion effects would produce a predictable ... More
Non-Lorentzian RG flows and SupersymmetryApr 10 2019We describe a general process where a non-Lorentzian rescaling of a supersymmetric field theory leads to a scale-invariant fixed point action without Lorentz invariance but where the supersymmetry is preserved or even enhanced. We apply this procedure ... More
A geometric inequality for convex free boundary hypersurfaces in the unit ballJun 20 2016We use the inverse mean curvature flow with a free boundary perpendicular to the sphere to prove a geometric inequality involving the Willmore energy for convex hypersurfaces of dimension $n\geq 3$ with boundary on the sphere.
Non-Lorentzian Field Theories with Maximal Supersymmetry and Moduli Space DynamicsAug 08 2018Oct 17 2018We present gauge theories in 2+1 and 4+1 dimensions with 16 supersymmetries which are invariant under rotations and translations but not boosts. The on-shell conditions reduce the dynamics to motion on a moduli space of BPS states graded by a topologically ... More
Charged Chiral Fermions from M5-BranesFeb 21 2018Apr 16 2018We study M5-branes wrapped on a multi-centred Taub-NUT space. Reducing to String Theory on the circle fibration leads to D4-branes intersecting with D6-branes. D-braneology shows that there are additional charged chiral fermions from the open strings ... More
New approaches of source-sink metapopulations decoupling the roles of demography and dispersalOct 17 2012Source-sink systems are metapopulations of habitat patches with different, and possibly temporally varying, habitat qualities, which are commonly used in ecology to study the fate of spatially extended natural populations. We propose new techniques that ... More
The peripatric coalescentMar 13 2013We consider a dynamic metapopulation involving one large population of size N surrounded by colonies of size \varepsilon_NN, usually called peripheral isolates in ecology, where N\to\infty and \varepsilon_N\to 0 in such a way that \varepsilon_NN\to\infty. ... More
Splitting trees stopped when the first clock rings and Vervaat's transformationOct 13 2011We consider a branching population where individuals have i.i.d.\ life lengths (not necessarily exponential) and constant birth rate. We let $N_t$ denote the population size at time $t$. %(called homogeneous, binary Crump--Mode--Jagers process). We further ... More
On Conway mutation and link homologyJan 04 2017Jan 30 2017We give a new, elementary proof that Khovanov homology with $\mathbb{Z}/2\mathbb{Z}$--coefficients is invariant under Conway mutation. This proof also gives a strategy to prove Baldwin and Levine's conjecture that $\delta$--graded knot Floer homology ... More
Symplectic surfaces and bridge positionApr 10 2019We give a new characterization of symplectic surfaces in CP^2 via bridge trisections. Specifically, a minimal genus surface in CP^2 is smoothly isotopic to a symplectic surface if and only if it is smoothly isotopic to a surface in transverse bridge position. ... More
Recovering the Brownian Coalescent Point Process from the Kingman Coalescent by Conditional SamplingNov 04 2016We consider a continuous population whose dynamics is described by the standard stationary Fleming-Viot process, so that the genealogy of $n$ uniformly sampled individuals is distributed as the Kingman $n$-coalescent. In this note, we study some genealogical ... More
Coagulation-transport equations and the nested coalescentsJul 24 2018The nested Kingman coalescent describes the dynamics of particles (called genes) contained in larger components (called species), where pairs of species coalesce at constant rate and pairs of genes coalesce at constant rate provided they lie within the ... More
The law of large numbers for the maximum of almost Gaussian log-correlated fields coming from random matricesNov 27 2016We compute the leading asymptotics as $N\to\infty$ of the maximum of the field $Q_N(q)= \log\det|q- A_N|$, $q\in \mathbb{C}$, for any unitarily invariant Hermitian random matrix $A_N$ associated to a non-critical real-analytic potential. Hence, we verify ... More
M2-Branes and Background FieldsAug 20 2009We discuss the coupling of multiple M2-branes to the background 3-form and 6-form gauge fields of eleven-dimensional supergravity, including the coupling of the Fermions. In particular we show in detail how a natural generalization of the Myers flux-terms, ... More
Enhanced Coset Symmetries and Higher Derivative CorrectionsMar 31 2006Aug 17 2006After dimensional reduction to three dimensions, the lowest order effective actions for pure gravity, M-theory and the Bosonic string admit an enhanced symmetry group. In this paper we initiate study of how this enhancement is affected by the inclusion ... More
Comments on Multiple M2-branesDec 21 2007Feb 02 2008Recently a three-dimensional field theory was derived that is consistent with all the symmetries expected of the worldvolume action for multiple M2-branes. In this note we examine several physical predictions of this model and show that they are in agreement ... More
Quantizing the (0,4) Supersymmetric ADHM Sigma ModelAug 09 1995Dec 01 1995We discuss the quantization of the ADHM sigma model. We show that the only quantum contributions to the effective theory come from the chiral anomalies and compute the first and second order terms. Finally the limit of vanishing instanton size is discussed. ... More
Inflated Discrete Beta Regression Models for Likert and Discrete Rating Scale OutcomesMay 19 2014Discrete ordinal responses such as Likert scales are regularly proposed in questionnaires and used as dependent variable in modeling. The response distribution for such scales is always discrete, with bounded support and often skewed. In addition, one ... More
Predicting the loss of phylogenetic diversity under non-stationary diversification modelsJun 12 2013For many taxa, the current high rates of extinction are likely to result in a significant loss of biodiversity. The evolutionary heritage of biodiversity is frequently quantified by a measure called phylogenetic diversity (PD). We predict the loss of ... More
The coalescent point process of branching treesJan 12 2011Feb 12 2013We define a doubly infinite, monotone labeling of Bienayme-Galton-Watson (BGW) genealogies. The genealogy of the current generation backwards in time is uniquely determined by the coalescent point process $(A_i; i\ge 1)$, where $A_i$ is the coalescence ... More
Covering relations of k-Grassmannian permutations of type BMar 08 2018The main result of this work is the characterization of the covering relations of the Bruhat order of the maximal parabolic quotients of type B. Our approach is mainly combinatorial and is based in the pattern of the corresponding permutations also called ... More
Gaussian and non-Gaussian fluctuations for mesoscopic linear statistics in determinantal processesApr 24 2015We study mesoscopic linear statistics for a class of determinantal point processes which interpolates between Poisson and Gaussian Unitary Ensemble statistics. These processes are obtained by modifying the spectrum of the correlation kernel of the GUE ... More
The inverse mean curvature flow perpendicular to the sphereOct 20 2014We consider the smooth inverse mean curvature flow of strictly convex hypersurfaces with boundary embedded in $\mathbb{R}^{n+1},$ which are perpendicular to the unit sphere from the inside. We prove that the flow hypersurfaces converge to the embedding ... More
Three-Algebras and N=6 Chern-Simons Gauge TheoriesJul 01 2008Dec 19 2008We derive the general form for a three-dimensional scale-invariant field theory with N=6 supersymmetry, SU(4) R-symmetry and a U(1) global symmetry. The results can be written in terms of a 3-algebra in which the triple product is not antisymmetric. For ... More
Duality Groups, Automorphic Forms and Higher Derivative CorrectionsNov 29 2006Feb 21 2007We study the higher derivative corrections that occur in type II superstring theories in ten dimensions or less. Assuming invariance under a discrete duality group G(Z) we show that the generic functions of the scalar fields that occur can be identified ... More
Moduli and Brane IntersectionsSep 17 2002Nov 13 2002We discuss the worldvolume description of intersecting D-branes, including the metric on the moduli space of deformations. We impose a choice of static gauge that treats all the branes on an equal footing and describes the intersection of D-branes as ... More
Topological Massive Sigma ModelsDec 01 1994May 03 1995In this paper we construct topological sigma models which include a potential and are related to twisted massive supersymmetric sigma models. Contrary to a previous construction these models have no central charge and do not require the manifold to admit ... More
Macro-evolutionary models and coalescent point processes: The shape and probability of reconstructed phylogeniesAug 06 2013Forward-time models of diversification (i.e., speciation and extinction) produce phylogenetic trees that grow "vertically" as time goes by. Pruning the extinct lineages out of such trees leads to natural models for reconstructed trees (i.e., phylogenies ... More
Asymptotic behavior of local times of compound Poisson processes with drift in the infinite variance caseJun 17 2012May 23 2013Consider compound Poisson processes with negative drift and no negative jumps, which converge to some spectrally positive L\'evy process with non-zero L\'evy measure. In this paper we study the asymptotic behavior of the local time process, in the spatial ... More
The weak convergence of regenerative processes using some excursion path decompositionsFeb 13 2012May 23 2013We consider regenerative processes with values in some Polish space. We define their \epsilon-big excursions as excursions e such that f(e)>\epsilon, where f is some given functional on the space of excursions which can be thought of as, e.g., the length ... More
Splitting trees with neutral Poissonian mutations II: Largest and Oldest familiesAug 24 2011We consider a supercritical branching population, where individuals have i.i.d. lifetime durations (which are not necessarily exponentially distributed) and give birth (singly) at constant rate. We assume that individuals independently experience neutral ... More
Adaptive dynamics in logistic branching populationsJun 28 2007We consider a trait-structured population subject to mutation, birth and competition of logistic type, where the number of coexisting types may fluctuate. Applying a limit of rare mutations to this population while keeping the population size finite leads ... More
Deep Adaptive Learning for Writer Identification based on Single Handwritten Word ImagesSep 28 2018There are two types of information in each handwritten word image: explicit information which can be easily read or derived directly, such as lexical content or word length, and implicit attributes such as the author's identity. Whether features learned ... More
Stability of Wavelengths and Spatiotemporal Intermittency in Coupled Map LatticesAug 01 1994In relation to spatiotemporal intermittency, as it can be observed in coupled map lattices, we study the stability of different wavelengths in competition. Introducing a two dimensional map, we compare its dynamics with the one of the whole lattice. We ... More
Past, growth and persistence of source-sink metapopulationsNov 10 2011Source-sink systems are metapopulations of patches that can be of variable habitat quality. They can be seen as graphs, where vertices represent the patches, and the weighted oriented edges give the probability of dispersal from one patch to another. ... More
The distribution of the overlapping functionOct 27 2011We consider the set of finite sequences of length n over a finite or countable alphabet C. We consider the function which associate each given sequence with the size of the maximum overlap with a (shifted) copy of itself. We compute the exact distribution ... More
Bridge trisections in $\mathbb{CP}^2$ and the Thom conjectureJul 26 2018In this paper, we develop new techniques for understanding surfaces in $\mathbb{CP}^2$ via bridge trisections. Trisections are a novel approach to smooth 4-manifold topology, introduced by Gay and Kirby, that provide an avenue to apply 3-dimensional tools ... More
From the divergence between two measures to the shortest path between two observablesNov 04 2016Dec 27 2017We consider two independent and stationary measures over $\chi^\mathbb{N}$, where $\chi$ finite or countable alphabet. For each pair of $n$-strings in the product space we define $T_n^{(2)}$ as the length of the shortest path connecting one string to ... More
Introduction to Black Hole EvaporationOct 30 2013Jan 16 2014These lecture notes are an elementary and pedagogical introduction to the black hole evaporation, based on a lecture given by the author at the Ninth Modave Summer School in Mathematical Physics and are intended for PhD students. First, quantum field ... More