Results for "Johannes Staguhn"

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Characterizing Extragalactic Anomalous Microwave Emission in NGC 6946 with CARMANov 25 2014Using 1 cm and 3 mm CARMA and 2 mm GISMO observations, we follow up the first extragalactic detection of anomalous microwave emission (AME) reported by Murphy et al. 2010 in an extranuclear region (Enuc. 4) of the nearby face-on spiral galaxy NGC 6946. ... More
SOFIA/HAWC+ detection of a gravitationally lensed starburst galaxy at $z$ = 1.03Jul 17 2018Jul 19 2018We present the detection at 89 $\mu$m (observed frame) of the {\it Herschel}-selected gravitationally lensed starburst galaxy HATLASJ1429-0028 (also known as G15v2.19) in 15 minutes with the High-resolution Airborne Wideband Camera-plus (HAWC+) onboard ... More
350 micron Galactic Center Dust Observations with SHARC IIDec 06 2004We present first and preliminary submillimeter continuum images of the Galactic Center region obtained with the new Caltech Submillimeter Observatory facility camera SHARC II. The instrument allows 350 micron observations with unprecedented sensitivity ... More
Taking Census of Massive, Star-Forming Galaxies formed <1 Gyr After the Big BangMar 13 2019Two decades of effort have been poured into both single-dish and interferometric millimeter-wave surveys of the sky to infer the volume density of dusty star-forming galaxies (DSFGs, with SFR>100M$_\odot$ yr$^{-1}$) over cosmic time. Though obscured galaxies ... More
Dust formation, evolution, and obscuration effects in the very high-redshift universeMay 05 2014The evolution of dust at redshifts z>9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because ... More
SOFIA observations of S106: Dynamics of the warm gasMar 22 2012Context. The HII region/PDR/molecular cloud complex S106 is excited by a single O-star. The full extent of the warm and dense gas close to the star has not been mapped in spectrally resolved high-J CO or [CII] lines, so the kinematics of the warm, partially ... More
The far-infrared polarization spectrum of Rho Ophiuchi A from HAWC+/SOFIA observationsMay 02 2019We report on polarimetric maps made with HAWC+/SOFIA toward Rho Oph A, the densest portion of the Rho Ophiuchi molecular complex. We employed HAWC+ bands C (89 $\mu$m) and D (154 $\mu$m). The slope of the polarization spectrum was investigated by defining ... More
Constraining the Active Galactic Nucleus and Starburst Properties of the IR-luminous Quasar Host Galaxy APM 08279+5255 at Redshift 4 with SOFIAMar 21 2019We present far-IR photometry and infrared spectrum of the z=3.9114 quasar/starburst composite system APM 08279+5255 obtained using the Stratospheric Observatory for Infrared Astronomy (SOFIA)/HAWC+ and the Spitzer Space Telescope Infrared Spectrograph ... More
An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z GalaxiesJun 14 2018Deep, pencil-beam surveys from ALMA at 1.1-1.3mm have uncovered an apparent absence of high-redshift dusty galaxies, with existing redshift distributions peaking around $z\sim1.5-2.5$. This has led to a perceived dearth of dusty systems at $z>4$, and ... More
The Brightest Galaxies in the Dark Ages: Galaxies' Dust Continuum Emission During the Reionization EraMay 25 2018Though half of cosmic starlight is absorbed by dust and reradiated at long wavelengths (3$\mu$m-3mm), constraints on the infrared through millimeter galaxy luminosity function (the `IRLF') are poor in comparison to the rest-frame ultraviolet and optical ... More
First detections of the [NII] 122 μm line at high redshift: Demonstrating the utility of the line for studying galaxies in the early universeSep 07 2011Sep 09 2011We report the first detections of the [NII] 122 {\mu}m line from a high redshift galaxy. The line was strongly (> 6{\sigma}) detected from SMMJ02399-0136, and H1413+117 (the Cloverleaf QSO) using the Redshift(z) and Early Universe Spectrometer (ZEUS) ... More
Submillimeter Observations of CLASH 2882 and the Evolution of Dust in this GalaxySep 30 2015Two millimeter observations of the MACS J1149.6+2223 cluster have detected a source that was consistent with the location of the lensed MACS1149-JD galaxy at z=9.6. A positive identification would have rendered this galaxy as the youngest dust forming ... More
Quarkonium Spectroscopy: Beyond One-Gluon ExchangeJul 09 2007In this work an improved potential model for quarkonium spectra (charmonium, bottomonium) is constructed. Beside the one-gluon exchange and a linear confinement potential, the model includes systematically effects from two-gluon exchange and the induced ... More
On uniform approximation to successive powers of a real numberMar 30 2016Apr 20 2016We establish new inequalities involving classical exponents of Diophantine approximation. This allows for improving on the work of Davenport, Schmidt and Laurent concerning the maximum value of the exponent $\hat{\lambda}_{n}(\zeta)$ among all real transcendental ... More
Duality for Lie-Rinehart algebras and the modular classFeb 08 1997Jan 29 2004We introduce a notion of duality for a Lie-Rinehart algebra giving certain bilinear pairings in its cohomology generalizing the usual notions of Poincar\'e duality in Lie algebra cohomology and de Rham cohomology. We show that the duality isomorphisms ... More
The singularities of Yang-Mills connections for bundles on a surface. I. The local modelNov 22 1994Let $\Sigma$ be a closed surface, $G$ a compact Lie group, not necessarily connected, with Lie algebra $g$, endowed with an adjoint action invariant scalar product, let $\xi \colon P \to \Sigma$ be a principal $G$-bundle, and pick a Riemannian metric ... More
Topological quantization of boundary forces and the integrated density of statesNov 08 2003For quantum systems described by Schr\"odinger operators on the half-space $\RR^{d-1}\times\RR^{leq 0}$ the boundary force per unit area and unit energy is topologically quantised provided the Fermi energy lies in a gap of the bulk spectrum. Under this ... More
On The Algebraic Characterization of Aperiodic Tilings Related To ADE-Root SystemsOct 14 1992Dec 30 1992\noindent The algebraic characterization of classes of locally isomorphic aperiodic tilings, being examples of quantum spaces, is conducted for a certain type of tilings in a manner proposed by A. Connes. These $2$-dimensional tilings are obtained by ... More
Comments on the distinction between color- and flavor-branes and new D3-D7 solutions with eight superchargesJul 07 2010We investigate the distinction between color- and flavor-branes, that is usually made in the context of gauge/string duality with backreacting flavors. Our remarks are based on a series of examples concerning the role of source terms in relatively simple ... More
Nonparametric estimation in functional linear models with second order stationary regressorsJan 27 2009We consider the problem of estimating the slope parameter in functional linear regression, where scalar responses Y1,...,Yn are modeled in dependence of second order stationary random functions X1,...,Xn. An orthogonal series estimator of the functional ... More
Deformations of asymptotically cylindrical G_2 manifoldsMay 30 2007Mar 11 2009We prove that for a 7-dimensional manifold M with cylindrical ends the moduli space of exponentially asymptotically cylindrical torsion-free G_2 structures is a smooth manifold (if non-empty), and study some of its local properties. We also show that ... More
Reduction of Multiple Harmonic Sums and Harmonic PolylogarithmsFeb 18 2004May 03 2004The alternating and non-alternating harmonic sums and other algebraic objects of the same equivalence class are connected by algebraic relations which are induced by the product of these quantities and which depend on their index calss rather than on ... More
Discovery Potential of MSSM Higgs Bosons with ATLASDec 19 2005In this article the potential of the ATLAS experiment to discover MSSM Higgs bosons is discussed. Various Monte-Carlo studies for SM Higgs boson production and dedicated MSSM Higgs boson analyses are taken into account to investigate the discovery potential ... More
Results on searches for new physics at HERAMay 13 2003The H1 and ZEUS collaborations have searched for signals of physics beyond the Standard Model in ep collisions at a center-of-mass energy of 301-319 GeV. During the HERA I phase each experiment accumulated an integrated luminosity of about 110 pb^{-1} ... More
BPS-like potential for compactifications of heterotic M-theory?Sep 09 2011Nov 07 2011We analyze the possibility to rewrite the action of Horava-Witten theory in a BPS-like form, which means that it is given as a sum of squares of the supersymmetry conditions. To this end we compactify the theory on a seven dimensional manifold of SU(3) ... More
Recent development in parton shower multijet mergingJul 07 2016Higher order calculations are necessary to predict and describe measurements in high energy collider physics. In recent years multiple approaches to combine multiple next-to-leading (NLO) order corrections with parton showers had been presented. We present ... More
Efficient Completion of Weighted AutomataSep 13 2016We consider directed graphs with edge labels from a semiring. We present an algorithm that allows efficient execution of queries for existence and weights of paths, and allows updates of the graph: adding nodes and edges, and changing weights of existing ... More
Some notes on the regular graph defined by Schmidt and Summerer and uniform approximationJan 05 2016Jan 12 2016Within the study of parametric geometry of numbers W. Schmidt and L. Summerer introduced so-called regular graphs. Roughly speaking the successive minima functions for the classical simultaneous Diophantine approximation problem have a very special pattern ... More
Secure Numerical and Logical Multi Party OperationsNov 12 2015Jan 31 2016We derive algorithms for efficient secure numerical and logical operations using a recently introduced scheme for secure multi-party computation~\cite{sch15} in the semi-honest model ensuring statistical or perfect security. To derive our algorithms for ... More
Discrete quantum geometries and their effective dimensionOct 29 2015In several approaches towards a quantum theory of gravity, such as group field theory and loop quantum gravity, quantum states and histories of the geometric degrees of freedom turn out to be based on discrete spacetime. The most pressing issue is then ... More
Describing the Heat Transport of Turbulent Rayleigh--Bénard Convection by POD methodsOct 23 2015Rayleigh--B\'enard convection, which is the buoyancy-induced motion of a fluid enclosed between two horizontal plates, is an idealised setup to study thermal convection. We analyse the modes that transport the most heat between the plates by computing ... More
G-bundles on the absolute Fargues-Fontaine curveJun 03 2016We prove that the category of vector bundles on the absolute Fargues-Fontaine curve is canonically equivalent to the category of isocrystals. We deduce a similar result for G-bundles for some arbitrary reductive group G over a p-adic local field.
Measuring Object-Oriented Design PrinciplesFeb 23 2016The idea of automatizing the assessment of objectoriented design is not new. Different approaches define and apply their own quality models, which are composed of single metrics or combinations thereof, to operationalize software design. However, single ... More
Paradigm shifts. Part I. Collagen. Confirming and complementing the work of Henry SmallNov 27 2014Dec 07 2014The paradigm shift in collagen research during the early 1970s marked by the discovery of the collagen precursor molecule procollagen was traced using co-citation analysis and title word frequency determination, confirming previous work performed by Henry ... More
Change-point tests under local alternatives for long-range dependent processesJun 24 2015We consider the change-point problem for the marginal distribution of subordinated Gaussian processes that exhibit long-range dependence. The asymptotic distributions of Kolmogorov-Smirnov- and Cram\'er-von Mises type statistics are investigated. A special ... More
Normality of algebras over commutative rings, crossed pairs, and the Teichmueller classDec 22 2015Let S be a commutative unitary ring, Q a group that acts on S, and let R be the subring of S fixed under Q. A Q-normal S-algebra consists of a central S-algebra A and a homomorphism s from Q to the group Out(A) of outer automorphisms of A that lifts the ... More
Deformations of $Ξ(s)=Ξ(1-s)$ and the heat equationOct 13 2015This paper studies deformations of the well-known $\Xi(s)=\Xi(1-s)$ equation for the Riemann $\Xi$ function satisfied by $\Xi_\rho(s):=\int_{0}^\infty\frac{{\d}t}{t}{t^{\frac{s}{2}}}\Psi(t)e^{-\rho\ln^2(t)}$ where ${\Psi(t)=\sum_{n\in\mathbb{N}^+}e^{-\pi{n}^2t}}$. ... More
Matching effective few-nucleon theories to QCDSep 25 2015May 17 2016The emergence of complex macroscopic phenomena from a small set of parameters and microscopic concepts demonstrates the power and beauty of physical theories. A theory which relates the wealth of data and peculiarities found in nuclei to the small number ... More
The spinorial energy functional: solutions of the gradient flow on Berger spheresOct 16 2015We study the negative gradient flow of the spinorial energy functional (introduced by Ammann, Wei{\ss}, and Witt) on 3-dimensional Berger spheres. For a certain class of spinors we show that the Berger spheres collapse to a 2-dimensional sphere. Moreover, ... More
A General Multi-Party Protocol for Minimal Communication and Local ComputationAug 31 2015Jan 31 2016A client wishes to outsource computation on confidential data to a network of servers. He does not trust a server on its own, but believes that servers do not collude. To solve this problem we introduce a new scheme called \emph{JOS} for perfect security ... More
Drawing and Analyzing Causal DAGs with DAGittyAug 19 2015DAGitty is a software for drawing and analyzing causal diagrams, also known as directed acyclic graphs (DAGs). Functions include identification of minimal sufficient adjustment sets for estimating causal effects, diagnosis of insufficient or invalid adjustment ... More
Research at UNIS - The University Centre in Svalbard. A bibliometric studyMay 25 2014Jun 17 2014The scientific output 1994-2014 of the University Centre in Svalbard (UNIS) was bibliometrically analysed. It was found that the majority of the papers have been published as international cooperations and rank above world average. Analysis of the content ... More
Functional linear instrumental regression under second order stationarityMar 04 2016We consider the problem of estimating the slope parameter in functional linear instrumental regression, where in the presence of an instrument W, i.e., an exogenous random function, a scalar response Y is modeled in dependence of an endogenous random ... More
How Are Programs Found? Speculating About Language Ergonomics With Curry-HowardDec 02 2016Functional languages with strong static type systems have beneficial properties to help ensure program correctness and reliability. Surprisingly, their practical significance in applications is low relative to other languages lacking in those dimensions. ... More
The Martingale Property in the Context of Stochastic Differential EquationsJun 02 2013Apr 26 2015This note studies the martingale property of a nonnegative, continuous local martingale Z, given as a nonanticipative functional of a solution to a stochastic differential equation. The condition states that Z is a (uniformly integrable) martingale if ... More
The low-dimensional homotopy of the stable mapping class groupJul 06 2007Due to the deep work of Tillmann, Madsen, Weiss and Galatius, the cohomology of the stable mapping class group $\gaminf$ is known with rational or finite field coefficients. Little is known about the integral cohomology. In this paper, we study the first ... More
Ricci-flat deformations and special holonomyAug 03 2010Let G be one of the Ricci-flat holonomy groups SU(n), Sp(n), Spin(7) or G_2, and M a compact manifold of dimension 2n, 4n, 8 or 7, respectively. We prove that the natural map from the moduli space of torsion-free G-structures on M to the moduli space ... More
The Weight in EnumerationDec 02 2016In our setting enumeration amounts to generate all solutions of a problem instance without duplicates. We address the problem of enumerating the models of B-formulae. A B-formula is a propositional formula whose connectives are taken from a fixed set ... More
Rational approximation to surfaces defined by polynomials in one variableJan 12 2016We study the rational approximation properties of special manifolds defined by a set of polynomials with rational coefficients. Mostly we will assume the case of all polynomials to depend on only one variable. In this case the manifold can be viewed as ... More
On the spectrum of positive finite-rank operators with a partition of unity propertyMar 18 2014We characterize the spectrum of positive linear operators $T:X \to Y$, where $X$ and $Y$ are complex Banach function spaces with unit $1$, having finite rank and a partition of unity property. Then all the points in the spectrum are eigenvalues of $T$ ... More
The Lie algebra perturbation lemmaAug 29 2007Oct 16 2007Let g be a differential graded Lie algebra and suppose given a contraction of chain complexes of g onto a general chain complex M. We show that the data determine an sh-Lie algebra structure on M, that is, a coalgebra perturbation of the coalgebra differential ... More
On uniform approximation to successive powers of a real numberMar 30 2016Jan 11 2017We establish new inequalities involving classical exponents of Diophantine approximation. This allows for improving on the work of Davenport, Schmidt and Laurent concerning the maximum value of the exponent $\hat{\lambda}_{n}(\zeta)$ among all real transcendental ... More
Power Utility Maximization in Discrete-Time and Continuous-Time Exponential Levy ModelsMar 29 2011Apr 26 2012Consider power utility maximization of terminal wealth in a 1-dimensional continuous-time exponential Levy model with finite time horizon. We discretize the model by restricting portfolio adjustments to an equidistant discrete time grid. Under minimal ... More
Jantzen sum formula for restricted Verma modules over affine Kac-Moody algebras at the critical levelDec 01 2012May 21 2013For a restricted Verma module of an affine Kac-Moody algebra at the critical level we describe the Jantzen filtration and give an alternating sum formula which corresponds to the Jantzen sum formula of a baby Verma module over a modular Lie algebra. This ... More
Equivariant cohomology over Lie groupoids and Lie-Rinehart algebrasJul 31 2009Using the language and terminology of relative homological algebra, in particular that of derived functors, we introduce equivariant cohomology over a general Lie-Rinehart algebra and equivariant de Rham cohomology over a locally trivial Lie groupoid ... More
Research performance of UNU - A bibliometric analysis of the United Nations UniversityDec 15 2016The scientific paper output of the United Nations University (UNU) was bibliometrically analysed.It was found that (i) a noticeable continous paper output starts in 1995, (ii) about 65% of the research papers have been published as international cooperations ... More
Pattern equivariant functions and cohomologyNov 29 2002The cohomology of a tiling or a point pattern has originally been defined via the construction of the hull or the groupoid associated with the tiling or the pattern. Here we present a construction which is more direct and therefore easier accessible. ... More
Resonances associated to a closed hyperbolic trajectory in dimension 2Sep 12 2002We consider resonances in the semi-classical limit, generated by a single closed hyperbolic orbit, for an operator on ${\bf R}^2$. We determine all such resonancess in a domain independent of the semi-classical parameter As an application we determine ... More
Eigenvalue distributions and Weyl laws for semi-classical non-self-adjoint operators in 2 dimensionsApr 25 2008In this note we compare two recent results about the distribution of eigenvalues for semi-classical pseudodifferential operators in two dimensions. For classes of analytic operators A. Melin and the author obtained a complex Bohr-Sommerfeld rule, showing ... More
A vanishing theorem for characteristic classes of odd-dimensional manifold bundlesFeb 27 2009Mar 09 2010We show how the Atiyah-Singer family index theorem for both, usual and self-adjoint elliptic operators fits naturally into the framework of the Madsen-Tillmann-Weiss spectra. Our main theorem concerns bundles of odd-dimensional manifolds. Using completely ... More
KMS states on the Toeplitz algebras of higher-rank graphsMay 23 2018The Toeplitz algebra $\mathcal{T}C^{*}(\Lambda)$ for a finite $k$-graph $\Lambda$ is equipped with a continuous one-parameter group $\alpha^{r}$ for each $ r\in \mathbb{R}^{k}$, obtained by composing the map $\mathbb{R} \ni t \to (e^{itr_{1}}, \dots , ... More
Quantifying macroeconomic expectations in stock markets using Google TrendsMay 01 2018Among other macroeconomic indicators, the monthly release of U.S. unemployment rate figures in the Employment Situation report by the U.S. Bureau of Labour Statistics gets a lot of media attention and strongly affects the stock markets. I investigate ... More
Real-analytic Eisenstein series via the Poincaré bundleJan 17 2018Feb 14 2018A classical construction of Katz gives a purely algebraic construction of real-analytic Eisenstein series using the Gau\ss--Manin connection on the universal elliptic curve. This approach gives a systematic way to study algebraic and $p$-adic properties ... More
Pseudo Maurer-Cartan perturbation algebra and pseudo perturbation lemmaDec 14 2018We introduce the pseudo Maurer-Cartan perturbation algebra, establish a structural result and explore the structure of this algebra. That structural result entails, as a consequence, what we refer to as the pseudo perturbation lemma. This lemma, in turn, ... More
Even an infinite bureaucracy eventually makes a decisionApr 01 2014We show that the fact that a political decision filtered through a finite tree of committees gives a determined answer generalises in some sense to infinite trees. This implies a new special case of the Matroid Intersection Conjecture.
A compactification of the moduli space of self-maps of $\mathbb{CP}^1$ using stable mapsApr 29 2016We present a new compactification $M(d,n)$ of the moduli space of self-maps of $\mathbb{CP}^1$ of degree $d$ with $n$ markings. It is constructed via GIT from the stable maps moduli space $\ ar M_{0,n}(\mathbb{CP}^1 \times \mathbb{CP}^1, (1,d))$. We show ... More
Auslander-Reiten triangles and Grothendieck groups of triangulated categoriesApr 04 2019We prove that if the Auslander-Reiten triangles generate the relations for the Grothendieck group of a Hom-finite Krull-Schmidt triangulated category with a cogenerator, then the category has only finitely many isomorphism classes of indecomposable objects ... More
Competing interactions and symmetry breaking in the Hubbard-Holstein modelJul 22 2009May 19 2010Competing interactions are often responsible for intriguing phase diagrams in correlated electron systems. Here we analyze the competition of instantaneous short range Coulomb interaction $U$ with the retarded electron-electron interaction induced by ... More
Barbasch-Sahi algebras and Dirac cohomologyAug 26 2016Sep 06 2016We define a class of algebras which are distinguished by a PBW property and an orthogonality condition, and which we call Hopf-Hecke algebras, since they generalize the Drinfeld Hecke algebras defined by Drinfeld. In the course of studying the orthogonality ... More
Index theory in spaces of noncompact manifolds I: Analytical foundationsAug 04 2016We develop elliptic regularity theory for Dirac operators in a very general framework: we consider Dirac operators linear over $C^*$-algebras, on noncompact manifolds, and in families which are not necessarily locally trivial fibre bundles.
A theoretical study of the dynamics of paramagnetic superrotors in external magnetic fieldsApr 13 2015Apr 20 2015We present a detailed theoretical study of oxygen molecules in high rotational states (molecular superrotors) interacting with an external magnetic field. The system shows rich dynamics, ranging from a spin-selective splitting of the angular distribution ... More
Extended moduli spaces and the Kan construction.II.Lattice gauge theoryJun 14 1995Let $Y$ be a CW-complex with a single 0-cell, $K$ its Kan group, a model for the loop space of $Y$, and let $G$ be a compact, connected Lie group. We give an explicit finite dimensional construction of generators of the equivariant cohomology of the geometric ... More
Symplectic and Poisson structures of certain moduli spaces. II. Projective representations of cocompact discrete planar groupsDec 21 1994Let $G$ be a Lie group with a biinvariant metric, not necessarily positive definite. It is shown that a certain construction carried out in an earlier paper for the fundamental group of a closed surface may be extended to an arbitrary infinite orientation ... More
Extensions of Lie-Rinehart algebras and the Chern-Weil constructionJun 01 1997A Chern-Weil construction for extensions of Lie-Rinehart algebras is introduced. This generalizes the classical Chern-Weil construction in differential geometry and yields characteristic classes for arbitrary extensions of Lie-Rinehart algebras. Some ... More
Geometric limits to geometric optical imaging with infinite, planar, non-absorbing sheetsJan 23 2009May 25 2009New ray-optical elements allow generalized refraction of light rays, but geometry imposes limitations on possible mappings between the positions of an object and its geometric image. Here I study the case of an infinite, planar, non-absorbing sheet that ... More
Bayesian evidence for non-zero theta_13 and CP-violation in neutrino oscillationsMay 20 2012Aug 31 2012We present the Bayesian method for evaluating the evidence for a non-zero value of the leptonic mixing angle theta_13 and CP-violation in neutrino oscillation experiments. This is an application of the well-established method of Bayesian model selection, ... More
Trust, but verify: benefits and pitfalls of least-squares refitting in high dimensionsJun 01 2013Least-squares refitting is widely used in high dimensional regression to reduce the prediction bias of l1-penalized estimators (e.g., Lasso and Square-Root Lasso). We present theoretical and numerical results that provide new insights into the benefits ... More
Spectral properties of Luther-Emery systemsFeb 15 1996We calculate the spectral function of the Luther-Emery model which describes one-dimensional fermions with gapless charge and gapped spin degrees of freedom. We find a true singularity with interaction dependent exponents on the gapped spin dispersion ... More
The homotopy type of a topological stackJan 21 2009The notion of the \emph{homotopy type} of a topological stack has been around in the literature for some time. The basic idea is that an atlas $X \to \mathfrak{X}$ of a stack determines a topological groupoid $\mathbb{X}$ with object space $X$. The homotopy ... More
Elliptic regularity for Dirac operators on families of noncompact manifoldsAug 04 2016Jan 18 2018We develop elliptic regularity theory for Dirac operators in a very general framework: we consider Dirac operators linear over $C^*$-algebras, on noncompact manifolds, and in families which are not necessarily locally trivial fibre bundles.
Non-equilibrium dynamics of gene expression and the Jarzynski equalityDec 03 2007In order to express specific genes at the right time, the transcription of genes is regulated by the presence and absence of transcription factor molecules. With transcription factor concentrations undergoing constant changes, gene transcription takes ... More
Statistical mechanics of random two-player gamesOct 22 1999Using methods from the statistical mechanics of disordered systems we analyze the properties of bimatrix games with random payoffs in the limit where the number of pure strategies of each player tends to infinity. We analytically calculate quantities ... More
Short time existence of the heat flow for Dirac-harmonic maps on closed manifoldsMay 24 2017The heat flow for Dirac-harmonic maps on Riemannian spin manifolds is a modification of the classical heat flow for harmonic maps by coupling it to a spinor. It was introduced by Chen, Jost, Sun, and Zhu as a tool to get a general existence program for ... More
On the C*-algebraic approach to topological phases for insulatorsSep 21 2015Feb 17 2017The notion of a topological phase of an insulator is based on the concept of homotopy between Hamiltonians. It therefore depends on the choice of a topological space to which the Hamiltonians belong. We advocate that this space should be the $C^*$-algebra ... More
Reductive group schemes over the Fargues-Fontaine curveMar 02 2017For an arbitrary non-archimedean local field we classify reductive group schemes over the corresponding Fargues-Fontaine curve by group schemes over the category of isocrystals. We then classify torsors under such reductive group schemes by a generalization ... More
Tunneling HamiltonianFeb 06 2013Mar 07 2013For the description of the transport of electrons across a quantum dot, which is tunnel coupled to leads at different chemical potentials, it is usual to assume that the total Hamiltonian of the composite system of the leads and the quantum dot is the ... More
A spectral method for integral formulations of medium-frequency scattering problemsAug 26 2005A fast method for the computation of layer potentials that arise in acoustic scattering is introduced. The principal idea is to split the singular kernel into a smooth and a local part. The potential due to the smooth part is computed efficiently using ... More
Cubic approximation to Sturmian continued fractionsMar 29 2016Sep 12 2017We determine the classical approximation constants $w_{3}(\zeta),w_{3}^{\ast}(\zeta),\lambda_{3}(\zeta)$ such as the uniform constants $\widehat{w}_{3}(\zeta),\widehat{w}_{3}^{\ast}(\zeta),\widehat{\lambda}_{3}(\zeta)$ associated to real numbers $\zeta$ ... More
Generalized Binomial Edge IdealsOct 30 2012This paper studies a class of binomial ideals associated to graphs with finite vertex sets. They generalize the binomial edge ideals, and they arise in the study of conditional independence ideals. A Gr\"obner basis can be computed by studying paths in ... More
Local limit theorem for the maximum of a random walkMar 28 2014Mar 31 2014Consider a family of $\Delta$-latticed aperiodic random walks $\{S^{(a)},0\le a\le a_0\}$ with increments $X_i^{(a)}$ and non-positive drift $-a$. Suppose that $\sup_{a\le a_0}\mathbf{E}[(X^{(a)})^2]<\infty$ and $\sup_{a\le a_0}\mathbf{E}[\max\{0,X^{(a)}\}^{2+\varepsilon}]<\infty$ ... More
Kaehler quantization and reductionJul 19 2002Apr 08 2004Exploiting a notion of Kaehler structure on a stratified space introduced elsewhere we show that, in the Kaehler case, reduction after quantization coincides with quantization after reduction: Key tools developed for that purpose are stratified polarizations ... More
Classical phase space singularities and quantizationOct 20 2006Simple classical mechanical systems and solution spaces of classical field theories involve singularities. In certain situations these singularities can be understood in terms of stratified Kaehler spaces. We give an overview of a research program whose ... More
Singularities and Poisson geometry of certain representation spacesDec 19 2000Playing off against each other the real and complex structures, we elucidate the local structure of certain representation spaces in the world of Poisson geometry. Particular cases of these spaces arise as moduli spaces of semistable holomorphic vector ... More
An Analytic Description of Local Intersection Numbers at Non-Archimedian Places for Products of Semi-Stable CurvesApr 10 2014We generalise a formula of Shou-Wu Zhang, which describes local arithmetic intersection numbers of three Cartier divisors with support in the special fibre on a a self-product of a semi-stable arithmetic surface using elementary analysis. By an approximation ... More
Weyl law for semi-classical resonances with randomly perturbed potentialsNov 15 2011Dec 21 2013In this work we consider semi-classical Schr\"odinger operators with potentials supported in a bounded strictly convex subset ${\cal O}$ of ${\bf R}^n$ with smooth boundary. Letting $h$ denote the semi-classical parameter, we consider certain classes ... More
The spectrogram expansion of Wigner functionsJul 01 2016May 01 2018Wigner functions generically attain negative values and hence are not probability densities. We prove an asymptotic expansion of Wigner functions in terms of Hermite spectrograms, which are probability densities. The expansion provides exact formulas ... More
Spectral properties of non-self-adjoint operatorsFeb 25 2010This text is a slightly expanded version of my 6 hour mini-course at the PDE-meeting in \'Evian-les-Bains in June 2009. The first part gives some old and recent results on non-self-adjoint differential operators. The second part is devoted to recent results ... More
The sh-Lie algebra perturbation LemmaOct 10 2007Feb 04 2010Let R be a commutative ring which contains the rationals as a subring and let g be a chain complex. Suppose given an sh-Lie algebra structure on g, that is, a coalgebra perturbation of the coalgebra differential on the cofree coaugmented differential ... More
Perturbations of selfadjoint operators with periodic classical flowMar 03 2003We consider non-selfadjoint perturbations of a self-adjoint $h$-pseudodifferential operator in dimension 2. In the present work we treat the case when the classical flow of the unperturbed part is periodic and the strength $\epsilon $ of the perturbation ... More
Fractal Models for Normal Subgroups of Schottky GroupsMay 31 2011Mar 31 2013For a normal subgroup $N$ of the free group $\F_d$ with at least two generators we introduce the radial limit set $\Lr(N,\Phi)$ of $N$ with respect to a graph directed Markov system $\Phi$ associated to $\F_d$. These sets are shown to provide fractal ... More