Results for "F. Niel"

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Density of quasismooth hypersurfaces in simplicial toric varietiesSep 23 2014Mar 23 2016This paper investigates the density of hypersurfaces in a projective normal simplicial toric variety over a finite field having a quasismooth intersection with a given quasismooth subscheme. The result generalizes the formula found by B. Poonen for smooth ... More
Factorization and weak amenability of A(X)Nov 28 2003We investigate weak amenability of the Banach algebra A(X) of approximable operators on a Banach space X and its relation to factorization properties of operators in A(X). We show that if A(X) is weakly amenable, then either A(X) is self-induced (a nice ... More
Computing basepoints of linear series in the planeMay 09 2018We present an algorithm for detecting basepoints of linear series of curves in the plane. Moreover, we give an algorithm for constructing a linear series of curves in the plane for given basepoints. The underlying method of these algorithms is the classical ... More
Local alignment of Markov chainsOct 05 2006We consider local alignments without gaps of two independent Markov chains from a finite alphabet, and we derive sufficient conditions for the number of essentially different local alignments with a score exceeding a high threshold to be asymptotically ... More
A Note on Unconditional Structures in Weak Hilbert SpacesApr 24 1992We prove that if a non-atomic separable Banach lattice in a weak Hilbert space, then it is lattice isomorphic to $L_2(0,1)$.
The unreasonable accuracy of the Jastrow approach in many-body physicsJul 14 2003We investigate in a simple model whether a Jastrow-based approach for a many-body system containing two-body interactions can be exact. By comparison with recent assertions to the contrary, we find that in general the exact wave function is \emph{not} ... More
Quark deconfinement as supernova explosion engine for massive blue-supergiant starsDec 23 2017Oct 27 2018Blue-supergiant stars develop into core-collapse supernovae --- one of the most energetic outbursts in the universe --- when all nuclear burning fuel is exhausted in the stellar core. Previous attempts failed to explain observed explosions of such stars ... More
Ancient mean curvature flows and their spacetime tracksJan 16 2019Feb 26 2019We study properly immersed ancient solutions of the codimension one mean curvature flow in $n$-dimensional Euclidean space, and classify the convex hulls of the subsets of space reached by any such flow. In particular, it follows that any compact convex ... More
Resonant-tunnelling-assisted crossing for subwavelength plasmonic slot waveguidesSep 22 2008We theoretically investigate the properties of crossing for two perpendicular subwavelength plasmonic slot waveguides. We show that, when encountering nano intersection, the crosstalk for the direct crossing is around 25%, almost same as throughout. In ... More
On Adjoint Additive ProcessesJan 11 2019Starting with an additive process $(Y_t)_{t\geq0}$, it is in certain cases possible to construct an adjoint process $(X_t)_{t\geq0}$ which is itself additive. Moreover, assuming that the transition densities of $(Y_t)_{t\geq0}$ are controlled by a natural ... More
Continuum models for twisted bilayer graphene: the effects of lattice deformation and hopping parameterMar 01 2019We analyze a description of twisted graphene bilayers, that incorporates deformation of the layers due to the nature modern interlayer potentials, and a modification of the hopping parameters between layers in the light of the classic Slonczewski-Weiss-McClure ... More
Lattice Deformation, Low Energy Models and Flat Bands in Twisted Graphene BilayersMar 01 2019Twisted graphene bilayers show a complex electronic structure, further modified by interaction effects. The main features can be obtained from effective models, which make use a few phenomenological parameters. We analyze the influence of effects at the ... More
A weak*-topological dichotomy with applications in operator theoryFeb 28 2013Feb 18 2014Denote by $[0,\omega_1)$ the locally compact Hausdorff space consisting of all countable ordinals, equipped with the order topology, and let $C_0[0,\omega_1)$ be the Banach space of scalar-valued, continuous functions which are defined on $[0,\omega_1)$ ... More
Twists and the electronic structure of graphitic materialsMar 20 2019We analyze the effect of twists on the electronic structure of configurations of infinite stacks of graphene layers. We focus on three different cases: an infinite stack where each layer is rotated with respect to the previous one by a fixed angle, two ... More
Towards a Unified Quark-Hadron Matter Equation of State for Applications in Astrophysics and Heavy-Ion CollisionsApr 26 2018May 28 2018We outline an approach to a unified equation of state for quark-hadron matter on the basis of a $\Phi-$derivable approach to the generalized Beth-Uhlenbeck equation of state for a cluster decomposition of thermodynamic quantities like the density. To ... More
Factorization of the identity through operators with large diagonalSep 10 2015Given a Banach space $X$ with an unconditional basis, we consider the following question: does the identity on $X$ factor through every bounded operator on $X$ with large diagonal relative to the unconditional basis? We show that on Gowers' space with ... More
Assumptions and Axioms: Mathematical Structures to Describe the Physics of Rigid BodiesMay 05 2010This paper challenges some of the common assumptions underlying the mathematics used to describe the physical world. We start by reviewing many of the assumptions underlying the concepts of real, physical, rigid bodies and the translational and rotational ... More
Factorization of the identity through operators with large diagonalSep 10 2015Nov 08 2017Given a Banach space~$X$ with an unconditional basis, we consider the following question: does the identity on~$X$ factor through every operator on~$X$ with large diagonal relative to the unconditional basis? We show that on Gowers' unconditional Banach ... More
Degrees of Freedom for Piecewise Lipschitz EstimatorsJan 14 2016Feb 10 2017A representation of the degrees of freedom akin to Stein's lemma is given for a class of estimators of a mean value parameter in $\mathbb{R}^n$. Contrary to previous results our representation holds for a range of discontinues estimators. It shows that ... More
Frobenius splitting of cotangent bundles of flag varieties and geometry of nilpotent conesSep 08 1998We use the G-invariant non-degenerate form on the Steinberg module to Frobenius split the cotangent bundle of a flag variety in good prime characteristics. This was previously only known for the general linear group. Applications are a vanishing theorem ... More
Enhanced transmission through arrays of subwavelength holes in gold films coated by a finite dielectric layerMar 08 2007Enhanced transmissions through a gold film with arrays of subwavelength holes are theoretically studied, employing the rigid full vectorial three dimensional finite difference time domain method. Influence of air-holes shape to the transmission is firstly ... More
Mesoscopic magnetism in dielectric photonic crystal meta materials: topology and inhomogeneous broadeningOct 19 2006We consider meta materials made from a two-dimensional dielectric rod-type photonic crystal. The magnetic response is studied within the recently developed homogenization theory and we in particular study the effects of topology and inhomogeneous broadening. ... More
Observational signature of near-extremal Kerr-like black holes in a modified gravity theory at the Event Horizon TelescopeJun 13 2018Nov 09 2018We study the shadows cast by near-extremal Kerr-MOG black holes for different values of the parameter in modified gravity (MOG). In particular, we consider an isotropic emitter orbiting near such black holes and analytically compute the positions, fluxes ... More
A unified quark-nuclear matter equation of state from the cluster virial expansion within the generalized Beth-Uhlenbeck approachDec 31 2018We consider a cluster expansion for strongly correlated quark matter where the clusters are baryons with spectral properties that are described within the generalized Beth-Uhlenbeck approach by a medium dependent phase shift. We employ a simple ansatz ... More
Linking interstellar and cometary O$_2$: a deep search for $^{16}$O$^{18}$O in the solar-type protostar IRAS 16293--2422May 31 2018Recent measurements carried out at comet 67P/C-G with the ${\it Rosetta}$ probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar ... More
From quantum to classical modelling of radiation reaction: a focus on the radiation spectrumFeb 08 2018Soon available multi petawatt ultra-high-intensity (UHI) lasers will allow us to probe high-amplitude electromagnetic fields interacting with either ultra-relativistic electron beams or hot plasmas in the so-called moderately quantum regime. The correct ... More
Photonic nanowire-based single-photon source with polarization controlMay 23 2016This document describes a modal method for optical simulations of structures with elliptical cross sections and its application to the design of the photonic nanowire (NW)-based single-photon source (SPS). The work was carried out in the framework of ... More
Self force on a scalar charge in Kerr spacetime: inclined circular orbitsAug 13 2014Feb 02 2015Accurately modeling astrophysical extreme-mass-ratio-insprials requires calculating the gravitational self-force for orbits in Kerr spacetime. The necessary calculation techniques are typically very complex and, consequently, toy scalar-field models are ... More
A degree bound for families of rational curves on surfacesFeb 11 2014Feb 20 2018We give an upper bound for the degree of rational curves in a family that covers a given birational ruled surface in projective space. The upper bound is stated in terms of the degree, sectional genus and arithmetic genus of the surface. We introduce ... More
Cohomology of G-sheaves in positive characteristicDec 19 2002Apr 13 2003Let X be a noetherian scheme defined over an algebraically closed field of positive characteristic p, and G be a finite group, of order divisible by p, acting on X. We introduce a refinement of the equivariant K-theory of X to take into account the information ... More
Impact of slow-light enhancement on optical propagation in active semiconductor photonic crystal waveguidesAug 21 2015We derive and validate a set of coupled Bloch wave equations for analyzing the reflection and transmission properties of active semiconductor photonic crystal waveguides. In such devices, slow-light propagation can be used to enhance the material gain ... More
Euclidean sums and Hamiltonian products of circles in the 3-sphereJun 08 2013Mar 18 2019We classify the singular loci of surfaces in the 3-sphere that are the pointwise Euclidean sum or Hamiltonian product of circles. Such surfaces are the union of circles in at least two ways. As an application we classify surfaces that are covered by both ... More
Minimal degree rational curves on real surfacesJun 13 2018We classify real families of minimal degree rational curves that cover an embedded rational surface. A corollary is that if the projective closure of a smooth surface is not biregular isomorphic to the projective closure of the unit-sphere, then the set ... More
Estimating coupling directions in the cardio-respiratory system using recurrence propertiesJun 04 2013The asymmetry of coupling between complex systems can be studied by conditional probabilities of recurrence, which can be estimated by joint recurrence plots. This approach is applied for the first time on experimental data: time series of the human cardio-respiratory ... More
A degree bound for families of rational curves on surfacesFeb 11 2014Sep 10 2015We give an upper bound for the degree of rational curves in a family that covers a given birational ruled surface in projective space. The upper bound is stated in terms of the degree, sectional genus and arithmetic genus of the surface. We introduce ... More
When Ext is a Batalin-Vilkovisky algebraOct 04 2016We show under what conditions the complex computing general Ext-groups carries the structure of a cyclic operad such that Ext becomes a Batalin-Vilkovisky algebra. This is achieved by transferring cyclic cohomology theories for the dual of a (left) Hopf ... More
Exceptional Jacobi polynomialsApr 04 2018Dec 21 2018In this paper we present a systematic way to describe exceptional Jacobi polynomials via two partitions. We give the construction of these polynomials and restate the known aspects of these polynomials in terms of their partitions. The aim is to show ... More
When Ext is a Batalin-Vilkovisky algebraOct 04 2016Jun 14 2018We show under what conditions the complex computing general Ext-groups carries the structure of a cyclic operad such that Ext becomes a Batalin-Vilkovisky algebra. This is achieved by transferring cyclic cohomology theories for the dual of a (left) Hopf ... More
Hypersurfaces with defectOct 13 2016A projective hypersurface $X \subseteq \mathbb P^n$ has defect if $h^i(X) \neq h^i(\mathbb P^n)$ for some $i \in \{n, \dots, 2n-2\}$ in a suitable cohomology theory. This occurs for example when $X \subseteq \mathbb P^4$ is not $\mathbb Q$-factorial. ... More
The passive and active periods for the intermittent use of an active sensor to detect an evasive targetDec 18 2013Your task is to detect a submarine with your active sonar. The submarine can hear your active sonar before you can detect him. If the submarine is fast enough he can evade you before you can detect him. How do you then detect him? If you are using your ... More
Clifford and Euclidean translations of circlesJun 08 2013Jul 13 2015Celestials are surfaces that contain at least two real circles through a general point. We present a partial classification of celestials in the three-sphere up to Moebius equivalence. In particular, we consider translational celestials, which are the ... More
Sur les représentations du groupe fondamental d'une variété privée d'un diviseur à croisements normaux simplesApr 10 2007Feb 15 2008Given a projective variety X over an algebraically closed field of characteristic zero, we show that finite parabolic bundles along a fixed simple normal crossings divisor D are in one to one correspondence with representations of the \'etale fundamental ... More
Push-outs of derivationsApr 10 2008Let A be a Banach algebra and let X be a Banach A -bimodule. In studying the bounded Hochschild cohomology groups H^1(A,X) it is often useful to extend a given derivation D: A-> X to a Banach algebra B containing A as an ideal, thereby exploiting (or ... More
Fibrés paraboliques et champ des racinesApr 20 2006Following ideas of Nori, Biswas, ..., we show that given an integer r>0, a noetherian scheme X, and an effective Cartier divisor D on it, the parabolic vector bundles on (X,D) with weights multiples of 1/r (in the sense of Maruyama-Yokogawa) are equivalent ... More
Your Rugby Mates Don't Need to Know your Colleagues: Triadic Closure with Edge ColorsNov 23 2018Given an undirected graph $G=(V,E)$ the NP-hard Strong Triadic Closure (STC) problem asks for a labeling of the edges as weak and strong such that at most $k$ edges are weak and for each induced $P_3$ in $G$ at least one edge is weak. In this work, we ... More
Destroying Bicolored $P_3$s by Deleting Few EdgesJan 11 2019We introduce and study the Bicolored $P_3$ Deletion problem defined as follows. The input is a graph $G=(V,E)$ where the edge set $E$ is partitioned into a set $E_b$ of blue edges and a set $E_r$ of red edges. The question is whether we can delete at ... More
Fast, Compact, and High Quality LSTM-RNN Based Statistical Parametric Speech Synthesizers for Mobile DevicesJun 20 2016Jun 22 2016Acoustic models based on long short-term memory recurrent neural networks (LSTM-RNNs) were applied to statistical parametric speech synthesis (SPSS) and showed significant improvements in naturalness and latency over those based on hidden Markov models ... More
Homogeneous Buchberger algorithms and Sullivant's computational commutative algebra challengeAug 16 2005We give a variant of the homogeneous Buchberger algorithm for positively graded lattice ideals. Using this algorithm we solve the Sullivant computational commutative algebra challenge.
Families of bitangent planes of space curves and minimal non-fibration familiesFeb 27 2013Jan 06 2014We define a cone curve to be a reduced sextic space curve which lies on a quadric cone and does not go through the vertex. We classify families of bitangent planes of cone curves. The methods we apply can be used for any space curve with ADE singularities, ... More
Batalin-Vilkovisky algebra structures on (Co)Tor and Poisson bialgebroidsMay 14 2013Dec 28 2014In this article, we extend our preceding studies on higher algebraic structures of (co)homology theories defined by a left bialgebroid (U,A). For a braided commutative Yetter-Drinfel'd algebra N, explicit expressions for the canonical Gerstenhaber algebra ... More
Algorithms for singularities and real structures of weak Del Pezzo surfacesFeb 27 2013Jan 01 2014In this paper we consider the classification of singularities (Du Val) and real structures (Wall) of weak Del Pezzo surfaces from an algorithmic point of view. It is well known that the singularities of weak Del Pezzo surfaces correspond to root subsystems. ... More
Interaction Corrections to Spin-Wave Theory in the Large-S Limit of the Quantum Heisenberg FerromagnetApr 09 2016Oct 04 2016The Quantum Heisenberg Ferromagnet can be naturally reformulated in terms of interacting bosons (called spin waves or magnons) as an expansion in the inverse spin size. We calculate the first order interaction correction to the free energy, as an upper ... More
Webs of rational curves on real surfaces and a classification of real weak del Pezzo surfacesJul 16 2018We classify webs of minimal degree rational curves on surfaces and give a criterion for webs being hexagonal. In addition, we classify Neron-Severi lattices of real weak del Pezzo surfaces. These two classifications are related to root subsystems of E8. ... More
Surfaces that are covered by two families of circlesFeb 27 2013Mar 01 2019We classify real surfaces that contain at least two circles through a general point. Our main Moebius invariant is the Neron-Severi lattice enhanced with an involution coming from the real structure.
Deriving the Gross-Pitaevskii equationApr 17 2014In experiments, Bose-Einstein condensates are prepared by cooling a dilute Bose gas in a trap. After the phase transition has been reached, the trap is switched off and the evolution of the condensate observed. The evolution is macroscopically described ... More
A functional renormalization group approach to thermodynamics of weakly interacting Bose gases: from linear to hydrodynamic fluctuationsFeb 19 2019We study weakly interacting Bose gases using the functional renormalization group with a hydrodynamic effective action. We use a scale-dependent parametrization of the boson fields developed previously that interpolates between a Cartesian representation ... More
Hyperfine-Structure-Induced Depolarization of Impulsively Aligned $\rm I_2$ MoleculesApr 12 2018A moderately intense $450$ fs laser pulse is used to create rotational wave packets in gas phase $\rm{I_2}$ molecules. The ensuing time-dependent alignment, measured by Coulomb explosion imaging with a delayed probe pulse, exhibits the characteristic ... More
Embeddings of homogeneous spaces in prime characteristicsFeb 16 1995Let $G$ be a reductive linear algebraic group. The simplest example of a projective homogeneous $G$-variety in characteristic $p$, not isomorphic to a flag variety, is the divisor $x_0 y_0^p+x_1 y_1^p+x_2 y_2^p=0$ in $P^2\times P^2$, which is $SL_3$ modulo ... More
Families of circles on surfacesFeb 27 2013Jan 01 2014We classify surfaces in 3-space that carry at least 2 families of real circles. Equivalently, we classify surfaces with at least 2 real circles through a generic closed point. We call such surfaces real celestials. We show that celestials are weak Del ... More
Surfaces that are covered by two families of circlesFeb 27 2013Jan 05 2019We classify real surfaces that contain at least two circles through a general point. Our main Moebius invariant is the Neron-Severi lattice enhanced with an involution coming from the real structure.
Themis-ml: A Fairness-aware Machine Learning Interface for End-to-end Discrimination Discovery and MitigationOct 18 2017As more industries integrate machine learning into socially sensitive decision processes like hiring, loan-approval, and parole-granting, we are at risk of perpetuating historical and contemporary socioeconomic disparities. This is a critical problem ... More
Efficient configurational-bias Monte-Carlo simulations of chain molecules with `swarms' of trial configurationsOct 09 2017Proposed here is a dynamic Monte-Carlo algorithm that is efficient in simulating dense systems of long flexible chain molecules. It expands on the configurational-bias Monte-Carlo method through the simultaneous generation of a large set of trial configurations. ... More
A rigidity result for crossed products of actions of Baumslag-Solitar groupsSep 29 2015Nov 01 2015Let BS(n_1,m_1) $\curvearrowright$ X_1 and BS(n_2,m_2) $\curvearrowright$ X_2 be two ergodic essentially free probability measure preserving actions of nonamenable Baumslag-Solitar groups whose canonical almost normal abelian subgroups act aperiodically. ... More
Gerstenhaber and Batalin-Vilkovisky structures on modules over operadsDec 05 2013Jan 22 2015In this article, we show under what additional ingredients a comp (or opposite) module over an operad with multiplication can be given the structure of a cyclic k-module and how the underlying simplicial homology gives rise to a Batalin-Vilkovisky module ... More
Minimal families of curves on surfacesFeb 27 2013Jan 06 2014A minimal family of curves on an embedded surface is defined as a 1-dimensional family of rational curves of minimal degree, which cover the surface. We classify such minimal families using constructive methods. This allows us to compute the minimal families ... More
Different approach to the modeling of nonfree particle diffusionApr 03 2018A new approach to the modeling of nonfree particle diffusion is presented. The approach uses a general setup based on geometric graphs (networks of curves), which means that particle diffusion in anything from arrays of barriers and pore networks to general ... More
Bounded Hochschild cohomology of Banach algebras with a matrix-like structureNov 28 2003Let B be a unital Banach algebra. A projection in B which is equivalent to the identitity may give rise to a matrix-like structure on any two-sided ideal A in B. In this set-up we prove a theorem to the effect that the bounded Hochschild cohomology H^n(A,A^*) ... More
Milnor-Witt Cycle ModulesNov 29 2018We generalize Rost's theory of cycle modules using Milnor-Witt K-theory instead of the classical Milnor K-theory. We obtain a (quadratic) setting to study general cycle complexes and their (co)homology groups. The usual constructions are developped: proper ... More
Computing curves on real rational surfacesMay 10 2018We present an algorithm for computing curves and families of curves of prescribed degree and geometric genus on real rational surfaces.
Gravitational waves from bodies orbiting the Galactic Center black hole and their detectability by LISAMar 05 2019We present the first fully relativistic study of gravitational radiation from bodies in circular equatorial orbits around the massive black hole at the Galactic Center, Sgr A* and we assess the detectability of various kinds of objects by the gravitational ... More
Contact angle hysteresis and oil film lubrication in electrowetting with two immiscible liquidsJan 08 2018Apr 12 2018Electrowetting (EW) of water drops in ambient oil has found a wide range of applications including lab-on-a-chip devices, display screens, and variable focus lenses. The efficacy of all these applications is dependent on the contact angle hysteresis (CAH), ... More
Moving frames applied to shell elasticityJul 19 2006Exterior calculus and moving frames are used to describe curved elastic shells. The kinematics follow from the Lie-derivative on forms whereas the dynamics via stress-forms.
Measuring Resonance Parameters of Heavy Higgs Bosons at TESLAAug 13 2003This study investigates the potential of the TESLA Linear Collider for measuring resonance parameters of Higgs bosons beyond the mass range studied so far. The analysis is based on the reconstruction of events from the Higgsstrahlung process e+e- -> HZ. ... More
A relative Shafarevich theoremApr 08 2002Suppose given a Galois etale cover Y -> X of proper non-singular curves over an algebraically closed field k of prime characteristic p. Let H be its Galois group, and G any finite extension of H by a p-group P. We give necessary and sufficient conditions ... More
Knotted boundaries and braid only form of braided beltsAug 12 2018The Helon model identifies Standard Model quarks and leptons with certain framed braids joined together at both ends by a connecting node (disk). These surfaces with boundary are called braided 3-belts (or simply belts). Twisting and braiding of ribbons ... More
Truncated Groebner fans and lattice idealsSep 11 2005We outline a generalization of the Groebner fan of a homogeneous ideal with maximal cells parametrizing truncated Groebner bases. This "truncated" Groebner fan is usually much smaller than the full Groebner fan and offers the natural framework for conversion ... More
Self-induced Banach algebrasNov 28 2003A Banach algebra A is self-induced if the multiplication is an isomorphism from the A-balanced projective tensor-square of A to A. The class of self-induced Banach algebras is a natural generalization of unital Banach algebras, providing a fertile framework ... More
Translationally invariant treatment of pair correlations in nuclei: I. Spin and isospin dependent correlationsJul 15 1996We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation operators. Our techniques are tailored to those nuclei that can be dealt with ... More
Deep NuSTAR and Swift Monitoring Observations of the Magnetar 1E 1841-045May 13 2015May 20 2015We report on a 350-ks NuSTAR observation of the magnetar 1E 1841-045 taken in 2013 September. During the observation, NuSTAR detected six bursts of short duration, with $T_{90}<1$ s. An elevated level of emission tail is detected after the brightest burst, ... More
A fields only version of the Lorentz Force Law: Particles replaced by their fieldsNov 20 2012We show that the Lorentz force law, F^L_1=q_1(E+v_1xB) being the charge on particle 1 interacting with the electromagnetic fields due to all other particles, can be written in a pure field form F^L_1=-\nabla_1 U^{EM}. In this expression U^{EM} is the ... More
Quantum Corrections to the Schwarzschild and Kerr MetricsNov 08 2002We examine the corrections to the lowest order gravitational interactions of massive particles arising from gravitational radiative corrections. We show how the masslessness of the graviton and the gravitational self interactions imply the presence of ... More
GRB010921: Localization and Observations by the HETE SatelliteJan 29 2002On September 21 at 18950.56 SOD (05:15:50.56) UT the FREGATE gamma-ray instrument on the High Energy Transient Explorer (HETE) detected a bright gamma-ray burst (GRB). The burst was also seen by the X-detector on the WXM X-ray instrument and was therefore ... More
No More Active Galactic Nuclei in Clumpy Disks Than in Smooth Galaxies at z~2 in CANDELS / 3D-HSTJul 28 2014We use CANDELS imaging, 3D-HST spectroscopy, and Chandra X-ray data to investigate if active galactic nuclei (AGNs) are preferentially fueled by violent disk instabilities funneling gas into galaxy centers at 1.3<z<2.4. We select galaxies undergoing gravitational ... More
Strange matter prospects within the string-flip modelOct 25 2017Jan 04 2018In this contribution we extend the recently developed two-flavor quark-matter string-flip model by including strange quarks. We discuss implications for compact stars.
Identifying a first-order phase transition in neutron star mergers through gravitational wavesSep 04 2018Jan 16 2019We identify an observable imprint of a first-order hadron-quark phase transition at supranuclear densities on the gravitational-wave (GW) emission of neutron star mergers. Specifically, we show that the dominant postmerger GW frequency f_peak may exhibit ... More
The Hidden K-edge Signal in K-edge ImagingJun 13 2015K-edge imaging is commonly used for viewing contrast pharmaceuticals in a variety of multi-energy x-ray imaging techniques, ranging from dual-energy and spectral computed tomography to fluoroscopy. When looking for the K-edge signal of a specific contrast, ... More
Dzyaloshinskii-Moriya interaction and the magnetic ground state in magnetoelectric LiCoPO$_4$Mar 21 2019Magnetic structures are investigated by means of neutron diffraction to shine a light on the intricate details that are believed to be key to understanding the magnetoelectric effect in LiCoPO$_4$ . At zero field, a spontaneous spin canting of $\varphi ... More
Finding flows in the one-way measurement modelNov 29 2006Feb 29 2008The one-way measurement model is a framework for universal quantum computation, in which algorithms are partially described by a graph G of entanglement relations on a collection of qubits. A sufficient condition for an algorithm to perform a unitary ... More
A complete algorithm to find flows in the one-way measurement modelMar 08 2006Feb 16 2007This article is the complement to [quant-ph/0611284], which proves that flows (as introduced by [quant-ph/0506062]) can be found efficiently for patterns in the one-way measurement model which have non-empty input and output subsystems of the same size. ... More
Fundamental gerbesOct 24 2016For a class of affine algebraic groups $\mathcal C$ over a field, we define the notions of $\mathcal C$-fundamental gerbe of a fibered category, generalizing what we had done in arXiv:1204.1260 for finite group schemes. We give sufficient conditions on ... More
Sub-Poissonian Phonon Lasing in Three-Mode OptomechanicsFeb 13 2015We propose to use the resonant enhancement of the parametric instability in an optomechanical system of two optical modes coupled to a mechanical oscillator to prepare mechanical states with sub-Poissonian phonon statistics. Strong single photon coupling ... More
Nonparametric likelihood based estimation of linear filters for point processesApr 01 2013Feb 12 2014We consider models for multivariate point processes where the intensity is given nonparametrically in terms of functions in a reproducing kernel Hilbert space. The likelihood function involves a time integral and is consequently not given in terms of ... More
Klein's double discontinuity revisited: what use is university mathematics to high school calculus?Jun 29 2013Mar 10 2014Much effort and research has been invested into understanding and bridging the gaps which many students experience in terms of contents and expectations as they begin university studies with a heavy component of mathematics, typically in the form of calculus ... More
Cyclic structures in algebraic (co)homology theoriesNov 15 2010This note discusses the cyclic cohomology of a left Hopf algebroid ($\times_A$-Hopf algebra) with coefficients in a right module-left comodule, defined using a straightforward generalisation of the original operators given by Connes and Moscovici for ... More
Black Holes in Higher-Dimensional GravityFeb 04 2008These lectures review some of the recent progress in uncovering the phase structure of black hole solutions in higher-dimensional vacuum Einstein gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e. static solutions with an event ... More
Air-clad fibers: pump absorption assisted by chaotic wave dynamics?Jul 09 2007Wave chaos is a concept which has already proved its practical usefulness in design of double-clad fibers for cladding-pumped fiber lasers and fiber amplifiers. In general, classically chaotic geometries will favor strong pump absorption and we address ... More
Dimensional asymptotics of effective actions on S^n, and proof of Bär-Schopka's conjectureSep 01 2007We study the dimensional asymptotics of the effective actions, or functional determinants, for the Dirac operator D and Laplacians \Delta +\beta R on round S^n. For Laplacians the behavior depends on ``the coupling strength'' \beta, and one cannot in ... More
Note sur la détermination algébrique du groupe fondamental pro-résoluble d'une courbe affineAug 01 2007May 07 2008Let X be a smooth projective algebraic curve of genus g minus $r\geq 1$ points defined over an algebraically closed field k of characteristic $p\geq 0$. The structure of the largest prime to p quotient of the \'etale fundamental group is well known by ... More
Semi-analytical approach to short-wavelength dispersion and modal properties of photonic crystal fibersJan 17 2005Feb 14 2005We consider photonic crystal fibers made from arbitrary base materials and derive a unified semi-analytical approach for the dispersion and modal properties which applies to the short-wavelength regime. In particular we calculate the dispersion and the ... More
Using Structurally Well-Defined Norbornyl-Bridged Acene Dimers to Map a Mechanistic Landscape for Correlated Triplet Formation in Singlet FissionJan 18 2019Structurally well-defined TIPS-acetylene substituted tetracene (TIPS BT1') and pentacene (TIPS BP1') dimers utilizing a [2.2.1] bicyclic norbornyl bridge have been studied -primarily using time-resolved spectroscopic methods - to uncover mechanistic details ... More