Results for "Nathaniel Roth"

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Monte Carlo Radiation Hydrodynamics with Implicit MethodsApr 17 2014Jan 28 2015We explore the application of Monte Carlo transport methods to solving coupled radiation-hydrodynamics problems. We use a time-dependent, frequency-dependent, 3-dimensional radiation transport code, that is special relativistic and includes some detailed ... More
An Arena for Multi-Messenger Astrophysics: Inspiral and Tidal Disruption of White Dwarfs by Massive Black HolesFeb 18 2019The tidal disruption of stars by (super-)massive black holes in galactic nuclei has been discussed in theoretical terms for about 30 years but only in the past decade have we been able to detect such events in substantial numbers. Thus, we are now starting ... More
A unified model for tidal disruption eventsMar 08 2018In the past few years wide-field optical and UV transient surveys as well as X-ray telescopes have allowed us to identify a few dozen candidate tidal disruption events (TDEs). While in theory the physical processes in TDEs are expected to be ubiquitous, ... More
What Sets the Line Profiles in Tidal Disruption Events?Jul 10 2017Mar 01 2018We investigate line formation in gas that is outflowing and optically thick to electron scattering, as may be expected following the tidal disruption of a star by a super-massive black hole. Using radiative transfer calculations, we show that the optical ... More
PSpectRe: A Pseudo-Spectral Code for (P)reheatingMay 11 2010Aug 20 2010PSpectRe is a C++ program that uses Fourier-space pseudo-spectral methods to evolve interacting scalar fields in an expanding universe. PSpectRe is optimized for the analysis of parametric resonance in the post-inflationary universe, and provides an alternative ... More
The Dynamics of Ultracompact HII RegionsNov 22 2013Many ultracompact HII regions exhibit a cometary morphology in radio continuum emission. In such regions, a young massive star is probably ablating, through its ultraviolet radiation, the molecular cloud clump that spawned it. On one side of the star, ... More
Arbitrary p-Gradient ValuesJul 19 2012Jan 19 2013For any prime number p and any positive real number {\alpha}, we construct a finitely generated group {\Gamma} with p-gradient equal to {\alpha}. This construction is used to show that there exist uncountably many pairwise non-commensurable groups that ... More
Rank gradient and p-gradient of amalgamated free products and HNN extensionsSep 15 2013Jul 17 2014We calculate the rank gradient and p-gradient of free products, free products with amalgamation over an amenable subgroup, and HNN extensions with an amenable associated subgroup. The notion of cost is used to compute the rank gradient of amalgamated ... More
On complex H-type Lie algebrasJun 10 2014Oct 14 2016H-type Lie algebras were introduced by Kaplan as a class of real Lie algebras generalizing the familiar Heisenberg Lie algebra $\mathfrak{h}^3$. The H-type property depends on a choice of inner product on the Lie algebra $\mathfrak{g}$. Among the H-type ... More
An introduction to HKR character theoryAug 06 2013The generalized character theory of Hopkins, Kuhn, and Ravenel is an important tool in the study of Morava E-theory and higher height phenomena in chromatic homotopy theory. In this paper, we provide an introduction to HKR character theory with many examples, ... More
Pseudoholomorphic quilts with figure eight singularityOct 14 2014We show that the novel figure eight singularity in a pseudoholomorphic quilt can be continuously removed when composition of Lagrangian correspondences is cleanly immersed. The proof of this result requires a collection of width-independent elliptic estimates ... More
Hypoelliptic heat kernel inequalities on H-type groupsJun 07 2014Dec 01 2016We study inequalities related to the heat kernel for the hypoelliptic sublaplacian on an H-type Lie group. Specifically, we obtain precise pointwise upper and lower bounds on the heat kernel function itself. We then apply these bounds to derive an estimate ... More
Gradient estimates for the subelliptic heat kernel on H-type groupsApr 11 2009Jun 24 2014We prove the following gradient inequality for the subelliptic heat kernel on nilpotent Lie groups $G$ of H-type: $$|\nabla P_t f| \le K P_t(|\nabla f|)$$ where $P_t$ is the heat semigroup corresponding to the sublaplacian on $G$, $\nabla$ is the subelliptic ... More
Precise estimates for the subelliptic heat kernel on H-type groupsOct 17 2008Jun 24 2014We establish precise upper and lower bounds for the subelliptic heat kernel on nilpotent Lie groups $G$ of H-type. Specifically, we show that there exist positive constants $C_1$, $C_2$ and a polynomial correction function $Q_t$ on $G$ such that $$C_1 ... More
Moduli spaces of witch curves topologically realize the 2-associahedraDec 04 2017For $r \geq 1$ and $\mathbf{n} \in \mathbb{Z}_{\geq0}^r\setminus\{\mathbf{0}\}$, we construct the compactified moduli space $\overline{2\mathcal{M}}_{\mathbf{n}}$ of witch curves of type $\mathbf{n}$. We equip $\overline{2\mathcal{M}}_{\mathbf{n}}$ with ... More
Supercharacter theories of type $A$ unipotent radicals and unipotent polytopesDec 10 2015Even with the introduction of supercharacter theories, the representation theory of many unipotent groups remains mysterious. This paper constructs a family of supercharacter theories for normal pattern groups in a way that exhibit many of the combinatorial ... More
Analysis and Probability on Infinite-Dimensional SpacesJul 13 2016Sep 07 2016These lecture notes contain an introduction to some of the fundamental ideas and results in analysis and probability on infinite-dimensional spaces, mainly Gaussian measures on Banach spaces. They originated as the notes for a topics course at Cornell ... More
The X-ray through Optical Fluxes and Line Strengths of Tidal Disruption EventsOct 28 2015Aug 11 2016Observations of luminous flares resulting from the possible tidal disruption of stars by supermassive black holes have raised a number of puzzles. Outstanding questions include the origin of the optical and ultraviolet (UV) flux, the weakness of hydrogen ... More
3-D Radiative Transfer Calculations of Radiation Feedback from Massive Black Holes: Outflow of Mass from the Dusty "Torus"Mar 31 2012Sep 10 2012Observational and theoretical arguments suggest that the momentum carried in mass outflows from AGN can reach several times L / c, corresponding to outflow rates of hundreds of solar masses per year. Radiation pressure on lines alone may not be sufficient ... More
The Compass Project: Charting a New Course in Physics EducationNov 20 2012Jan 11 2013This article tells the story of the founding of the Compass Project at UC Berkeley and describes its impacts. The Compass Project is a self-formed group of graduate and undergraduate students in the physical sciences. Its goals are to improve undergraduate ... More
Assessing Wikipedia-Based Cross-Language Retrieval ModelsJan 10 2014This work compares concept models for cross-language retrieval: First, we adapt probabilistic Latent Semantic Analysis (pLSA) for multilingual documents. Experiments with different weighting schemes show that a weighting method favoring documents of similar ... More
Pinching of the First Eigenvalue of the Laplacian and almost-Einstein Hypersurfaces of the Euclidean SpaceFeb 07 2007In this paper, we prove new pinching theorems for the first eigenvalue of the Laplacian on compact hypersurfaces of the Euclidean space. These pinching results are associated with the upper bound for the first eigenvalue in terms of higher order mean ... More
Importance Truncation for Large-Scale Configuration Interaction ApproachesMar 26 2009We introduce an iterative importance truncation scheme which aims at reducing the dimension of the model space of configuration interaction approaches by an a priori selection of the physically most relevant basis states. Using an importance measure derived ... More
On the stability of the Wulff shapeNov 15 2015Given a positive function F on S n satisfying an appropriate con-vexity assumption, we consider hypersurfaces for which a linear combination of some higher order anisotropic curvatures is constant. We define the varia-tional problem for which these hypersurfaces ... More
Standard Model FitsMay 12 2004The status of the electroweak precision measurements as of winter 2004 and the global test of the Standard Model are discussed. Important input data are the precision variables measured on the Z resonance at LEP and SLC and the measurements of the W mass ... More
Should We Adjust for the Test for Pre-trends in Difference-in-Difference Designs?Apr 04 2018May 02 2018The common practice in difference-in-difference (DiD) designs is to check for parallel trends prior to treatment assignment, yet typical estimation and inference does not account for the fact that this test has occurred. I analyze the properties of the ... More
Counting Restricted Homomorphisms via Möbius Inversion over Matroid LatticesJun 26 2017We present a framework for the complexity classification of parameterized counting problems that can be formulated as the summation over the numbers of homomorphisms from small pattern graphs H_1,...,H_l to a big host graph G with the restriction that ... More
Constant Slope Models for Finitely Generated MapsJul 14 2017We study countably monotone and Markov interval maps. We establish sufficient conditions for uniqueness of a conjugate map of constant slope. We explain how global window perturbation can be used to generate a large class of maps satisfying these conditions. ... More
On the category of Euclidean configuration spaces and associated fibrationsApr 06 2009We calculate the Lusternik-Schnirelmann category of the k-th ordered configuration spaces F(R^n,k) of R^n and give bounds for the category of the corresponding unordered configuration spaces B(R^n,k) and the sectional category of the fibrations pi^n_k: ... More
Comment on `Formation of a Dodecagonal Quasicrystalline Phase in a Simple Monatomic Liquid'Jun 12 1997In a recent paper M. Dzugutov, Phys. Rev. Lett. 70 2924 (1993), describes a molecular dynamics cooling simulation where he obtained a large monatomic dodecagonal quasicrystal from a melt. The structure was stabilized by a special potential [Phys. Rev. ... More
W Mass at LEP and Standard Model FitsMay 05 2006May 16 2006The W-mass measurements from LEP and the results of a global fit of the Standard Model parameters to the electroweak data are presented. Comprehensive studies of experimental systematic effects allowed a measurement of the W mass with an accuracy of better ... More
Pontryagin's maximum principle for the Loewner equation in higher dimensionsFeb 27 2014In this paper we develop a variational method for the Loewner equation in higher dimensions. As a result we obtain a version of Pontryagin's maximum principle from optimal control theory for the Loewner equation in several complex variables. Based on ... More
Analysis of neuronal sequences using pairwise biasesMar 09 2016Sequences of neuronal activation have long been implicated in a variety of brain functions. In particular, these sequences have been tied to memory formation and spatial navigation in the hippocampus, a region of mammalian brains. Traditionally, neuronal ... More
Spinorial Characterization of Surfaces into 3-dimensional homogeneous ManifoldsJun 21 2007We give a spinorial characterization of isometrically immersed surfaces into 3-dimensional homogeneous manifolds with 4-dimensional isometry group in terms of the existence of a particular spinor, called generalized Killing spinor. This generalizes results ... More
Pattern groups and a poset based Hopf monoidOct 03 2018The supercharacter theory of algebra groups gave us a representation theoretic realization of the Hopf algebra of symmetric functions in noncommuting variables. The underlying representation theoretic framework comes equipped with two canonical bases, ... More
A family of meta-Fibonacci sequences defined by variable order recursionsAug 26 2005Sep 30 2005We define a family of meta-Fibonacci sequences where the order of the of recursion at stage n is a variable r(n), and the n^{th} term of a sequence is the sum of the previous r(n) terms. For the terms of any such sequence, we give upper and lower bounds ... More
Brown-Peterson cohomology from Morava E-theorySep 18 2015We prove that the $p$-completed Brown-Peterson spectrum is a retract of a product of Morava $E$-theory spectra. As a consequence, we generalize results of Ravenel-Wilson-Yagita and Kashiwabara from spaces to spectra and deduce that the notion of good ... More
Brown-Peterson cohomology from Morava E-theorySep 18 2015Feb 19 2017We prove that the $p$-completed Brown-Peterson spectrum is a retract of a product of Morava $E$-theory spectra. As a consequence, we generalize results of Ravenel-Wilson-Yagita and Kashiwabara from spaces to spectra and deduce that the notion of good ... More
The combinatorics of $\mathrm{GL}_n$ generalized Gelfand--Graev charactersMay 04 2015Introduced by Kawanaka in order to find the unipotent representations of finite groups of Lie type, generalized Gelfand--Graev characters have remained somewhat mysterious. Even in the case of the finite general linear groups, the combinatorics of their ... More
Nonzero coefficients in restrictions and tensor products of supercharacters of $U_n(q)$Dec 09 2009The standard supercharacter theory of the finite unipotent upper-triangular matrices $U_n(q)$ gives rise to a beautiful combinatorics based on set partitions. As with the representation theory of the symmetric group, embeddings of $U_m(q)\subseteq U_n(q)$ ... More
First passage percolation and competition modelsMay 04 2010This paper is a survey of various results and techniques in first passage percolation, a random process modeling a spreading fluid on an infinite graph. The latter half of the paper focuses on the connection between first passage percolation and a certain ... More
$q$-Partition Algebra CombinatoricsJun 24 2008Sep 08 2009We compute the dimension $d_{n,r}(q) = \dim(\IR_q^r)$ of the defining module $\IR_q^r$ for the $q$-partition algebra. This module comes from $r$-iterations of Harish-Chandra restriction and induction on $\GL_n(\FF_q)$. This dimension is a polynomial in ... More
The structure of normal lattice supercharacter theoriesOct 02 2018The character theory of finite groups has numerous basic questions that are often already quite involved: enumerating of irreducible characters, their character formulas, point-wise product decompositions, and restriction/induction between groups. A supercharacter ... More
On Yoccoz Return FunctionsAug 23 2009We study the dynamics of complex polynomials. We obtain results on Poincare return maps defined on certain neighborhoods of a point with bounded orbit under a polynomial. We introduce a generalization of the Yoccoz tau-function, the Yoccoz return function, ... More
Exclusive Signals of an Extended Higgs SectorJul 20 2012Nov 27 2012Expectations for the magnitude of Higgs boson signals in standard Higgs search channels at the LHC relative to Standard Model (SM) expectations are investigated within the framework of various types of CP and flavor conserving two Higgs doublet models ... More
Rational cohomology from supersymmetric field theoriesMar 06 2014We show that Sullivan's model of rational differential forms on a simplicial set $X$ may be interpreted as a (kind of) $0|1$-dimensional supersymmetric quantum field theory over $X$, and, as a consequence, concordance classes of such theories represent ... More
Laser frequency upconversion in plasmas with finite ionization ratesMay 15 2019Laser frequency can be upconverted in a plasma undergoing ionization. For finite ionization rates, the laser pulse energy is partitioned into a pair of counter-propagating waves and static transverse currents. The wave amplitudes are determined by the ... More
Instability in Predictive MatterNov 29 2016We study the dynamics of a swarm in which agents have full knowledge of the physical laws governing the system they live in. Agents aim to maximize their resource uptake by solving these laws to predict the future of their environment and other agents. ... More
Collective Motion of Predictive SwarmsNov 29 2016Nov 06 2017Theoretical models of populations and swarms typically start with the assumption that the motion of agents is governed by the local stimuli. However, an intelligent agent, with some understanding of the laws that govern its habitat, can anticipate the ... More
Rescuing Massive Photons from the SwamplandOct 12 2018Stringent Swampland conjectures aimed at effective theories containing massive abelian vectors have recently been proposed (arXiv:1808.09966), with striking phenomenological implications. In this article, we show how effective theories that parametrically ... More
On the weakest version of distributional chaosDec 22 2014Mar 01 2016The aim of the paper is to correct and improve some results concerning distributional chaos of type 3. We show that in a general compact metric space, distributional chaos of type 3, denoted DC3, even when assuming the existence of an uncountable scrambled ... More
Sympathetically cooled molecular ions: from principles to first applicationsDec 05 2008We review the current status of the field of sympathetically cooled molecular ions, i.e. the method used for cooling the translational degrees of freedom, the techniques applied for detection and analysis of the cold trapped ion ensembles produced as ... More
Term Definitions Help Hypernymy DetectionJun 12 2018Existing methods of hypernymy detection mainly rely on statistics over a big corpus, either mining some co-occurring patterns like "animals such as cats" or embedding words of interest into context-aware vectors. These approaches are therefore limited ... More
Pinching of the first eigenvalue for second order operators on hypersurfaces of the Euclidean spaceOct 13 2015We prove stability results associated with upper bounds for the first eigenvalue of certain second order differential operators of divergence-type on hypersurfaces of the Euclidean space. We deduce some applications to $r$-stability as well as to almost-Einstein ... More
Iterative Residual Refinement for Joint Optical Flow and Occlusion EstimationApr 10 2019Deep learning approaches to optical flow estimation have seen rapid progress over the recent years. One common trait of many networks is that they refine an initial flow estimate either through multiple stages or across the levels of a coarse-to-fine ... More
No Semiconjugacy to a Map of Constant SlopeMar 11 2014We study countably piecewise continuous, piecewise monotone interval maps. We establish a necessary and sufficient criterion for the existence of a nondecreasing semiconjugacy to a map of constant slope in terms of the existence of an eigenvector of an ... More
Pushed beyond the brink: Allee effects, environmental stochasticity, and extinctionMay 07 2014A demographic Allee effect occurs when individual fitness, at low densities, increases with population density. Coupled with environmental fluctuations in demographic rates, Allee effects can have subtle effects on population persistence and extinction. ... More
Reply to Comment on ``Ab Initio Study of 40-Ca with an Importance Truncated No-Core Shell Model''Jan 09 2008We respond to Comment on our recent letter (Phys.Rev.Lett.99:092501,2007) by Dean et al (arXiv:0709.0449).
The Unitary Correlation Operator Method from a Similarity Renormalization Group PerspectiveMar 01 2007Apr 24 2007We investigate how the Unitary Correlation Operator Method (UCOM), developed to explicitly describe the strong short-range central and tensor correlations present in the nuclear many-body system, relates to the Similarity Renormalization Group (SRG), ... More
Dynamic structure factor of ultracold Bose and Fermi gases in optical latticesJul 14 2004We investigate the dynamic structure factor of atomic Bose and Fermi gases in one-dimensional optical lattices at zero temperature. The focus is on the generic behaviour of S(k,omega) as function of filling and interaction strength with the aim of identifying ... More
Phase Diagram of Bosonic Atoms in Two-Color SuperlatticesApr 02 2003We investigate the zero temperature phase diagram of a gas of bosonic atoms in one- and two-color standing-wave lattices in the framework of the Bose-Hubbard model. We first introduce some relevant physical quantities; superfluid fraction, condensate ... More
Phase diagram of trapped degenerate Fermi gases including effective s- and p-wave interactionsAug 15 2001The influence of s- and p-wave interactions on trapped degenerate one and two-component Fermi gases is investigated. The energy functional of a multicomponent Fermi gas is derived within the Thomas-Fermi approximation including the s- and p-wave terms ... More
Pade-resummed high-order perturbation theory for nuclear structure calculationsOct 19 2009We apply high-order many-body perturbation theory for the calculation of ground-state energies of closed-shell nuclei using realistic nuclear interactions. Using a simple recursive formulation, we compute the perturbative energy contributions up to 30th ... More
Multiphase coexistence in polydisperse colloidal mixturesAug 02 2006Dec 08 2006We study the phase behavior of mixtures of monodisperse colloidal spheres with a depletion agent which can have arbitrary shape and can possess a polydisperse size or shape distribution. In the low concentration limit, considered here, we can employ the ... More
Topological defect formation from 2PI effective action techniquesDec 06 2010Feb 02 2011We propose a quantum approach to nonequilibrium dynamics which combines the successful aspects of classical-statistical simulations on a lattice with the ability to take into account quantum corrections. It is based on the 2PI effective action for inhomogeneous ... More
Light Neutron-Rich Hypernuclei from the Importance-Truncated No-Core Shell ModelOct 13 2017Feb 28 2018We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from $^5_\Lambda$He to $^{11}_\Lambda$He and from $^7_\Lambda$Li to $^{12}_\Lambda$Li --- in the ab ... More
Symbolic regression of generative network modelsSep 08 2014Networks are a powerful abstraction with applicability to a variety of scientific fields. Models explaining their morphology and growth processes permit a wide range of phenomena to be more systematically analysed and understood. At the same time, creating ... More
Epistemic communities: description and hierarchic categorizationSep 06 2004Sep 07 2004Social scientists have shown an increasing interest in understanding the structure of knowledge communities, and particularly the organization of "epistemic communities", that is groups of agents sharing common knowledge concerns. However, most existing ... More
Study of muon pairs in hadronic events with bottom tag using L3 data recorded near the Z resonanceMay 03 2019A recent publication based on ALEPH $\mathrm{e}^+\mathrm{e}^-$ data taken near the Z resonance reports an excess, near 30 GeV, in the di-muon mass spectrum for events containing b quarks. In this paper we measure the di-muon mass spectrum for L3 data ... More
Seshadri constants, Diophantine approximation, and Roth's Theorem for arbitrary varietiesJun 12 2013Apr 27 2015In this paper, we associate an invariant $\alpha_{x}(L)$ to an algebraic point $x$ on an algebraic variety $X$ with an ample line bundle $L$. The invariant $\alpha$ measures how well $x$ can be approximated by rational points on $X$, with respect to the ... More
Conformal MetricsMay 15 2008This paper surveys some selected topics in the theory of conformal metrics and their connections to complex analysis, partial differential equations and conformal differential geometry.
Counting Induced Subgraphs: A Topological Approach to #W[1]-hardnessJul 05 2018We investigate the problem $\#\mathsf{IndSub}(\Phi)$ of counting all induced subgraphs of size $k$ in a graph $G$ that satisfy a given property $\Phi$. This continues the work of Jerrum and Meeks who proved the problem to be $\#\mathrm{W[1]}$-hard for ... More
Testing standard perturbation theory and the Eulerian local biasing scheme against N-body simulationsJan 07 2011Mar 21 2011We test third-order standard perturbation theory (SPT) as an approximation to non-linear cosmological structure formation. A novel approach is used to numerically calculate the three-dimensional dark matter density field using SPT from the initial conditions ... More
Can we really measure fnl from the galaxy power spectrum?May 14 2012Jul 02 2012The scale-dependent galaxy bias generated by primordial non-Gaussianity (PNG) can be used to detect and constrain deviations from standard single-field inflation. The strongest signal is expected in the local model for PNG, where the amplitude of non-Gaussianity ... More
Two Discourse Driven Language Models for SemanticsJun 17 2016Jun 27 2016Natural language understanding often requires deep semantic knowledge. Expanding on previous proposals, we suggest that some important aspects of semantic knowledge can be modeled as a language model if done at an appropriate level of abstraction. We ... More
The spinor representation formula in 3 and 4 dimensionsSep 02 2013In the literature, two approaches to the Weierstrass representation formula using spinors are known, one explicit, going back to Kusner & Schmitt, and generalized by Konopelchenko and Taimanov, and one abstract due to Friedrich, Bayard, Lawn and Roth. ... More
Binary hard-sphere fluids near a hard wallMar 16 2000By using the Rosenfeld density functional we determine the number density profiles of both components of binary hard-sphere fluids close to a planar hard wall as well as the corresponding excess coverage and surface tension. The comparison with published ... More
A Mathematical Model of MechanotransductionNov 24 2016This article reviews the mechanical bidomain model, a mathematical description how the extracellular matrix and intracellular cytoskeleton are coupled by integrin proteins. The fundamental hypothesis is that differences between intracellular and extracellular ... More
Position-aware Self-attention with Relative Positional Encodings for Slot FillingJul 09 2018This paper describes how to apply self-attention with relative positional encodings to the task of relation extraction. We propose to use the self-attention encoder layer together with an additional position-aware attention layer that takes into account ... More
TwoWingOS: A Two-Wing Optimization Strategy for Evidential Claim VerificationAug 10 2018Aug 28 2018Determining whether a given claim is supported by evidence is a fundamental NLP problem that is best modeled as Textual Entailment. However, given a large collection of text, finding evidence that could support or refute a given claim is a challenge in ... More
f-Biharmonic and bi-f-harmonic submanifolds of generalized space formsSep 27 2016We study f-biharmonic and bi-f-harmonic submanifolds in both generalized complex and Sasakian space forms. We prove necessary and sufficient condition for f-biharmonicity and bi-f-harmonicity in the general case and many particular cases. Some non-existence ... More
LUSIFER: a LUcid approach to SIx-FERmion productionJun 06 2002Sep 04 2002LUSIFER is a Monte Carlo event generator for all processes e+e-->6fermions, which is based on the multi-channel Monte Carlo integration technique and employs the full set of tree-level diagrams. External fermions are taken to be massless, but can be arbitrarily ... More
The affine stratification number and the moduli space of curvesJun 19 2004We define the affine stratification number asn X of a scheme X. For X equidimensional, it is the minimal number k such that there is a stratification of X by locally closed affine subschemes of codimension at most k. We show that the affine stratification ... More
Lattices for Dynamic, Hierarchic & Overlapping Categorization: the Case of Epistemic CommunitiesSep 04 2005We present a method for hierarchic categorization and taxonomy evolution description. We focus on the structure of epistemic communities (ECs), or groups of agents sharing common knowledge concerns. Introducing a formal framework based on Galois lattices, ... More
Universal locally univalent functions and universal conformal metrics with constant curvatureSep 29 2017Apr 03 2018We prove Runge-type theorems and universality results for locally univalent holomorphic and meromorphic functions. Refining a result of M. Heins, we also show that there is a universal bounded locally univalent function on the unit disk. These results ... More
Electronic excitation spectrum of doped organic thin films investigated using electron energy-loss spectroscopyFeb 25 2015The electronic excitation spectra of undoped, and potassium as well as calcium doped phenantrene-type hydrocarbons have been investigated using electron energy-loss spectroscopy (EELS) in transmission. In the undoped materials, the lowest energy excitations ... More
Skew Killing spinorsOct 10 2011In this paper, we study the existence of a skew Killing spinor (see the definition below) on 2 and 3-dimensional Riemannian spin manifolds. We establish the integrability conditions and prove that these spinor fields correspond to twistor spinors in the ... More
Collective excitations in deformed sd-shell nuclei from realistic interactionsSep 02 2014Background: Collective excitations of nuclei and their theoretical descriptions provide an insight into the structure of nuclei. Replacing traditional phenomenological interactions with unitarily transformed realistic nucleon-nucleon interactions increases ... More
Second RPA and correlated realistic interactionsMay 27 2008We examine the response of closed-shell nuclei using a correlated interaction, derived with the Unitary Correlation Operator Method (UCOM) from the Argonne V18 potential, in second RPA (SRPA) calculations. The same correlated two-body interaction is used ... More
Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell ModelMay 28 2007We propose an importance truncation scheme for the no-core shell model, which enables converged calculations for nuclei well beyond the p-shell. It is based on an a priori measure for the importance of individual basis states constructed by means of many-body ... More
Effective s- and p-Wave Contact Interactions in Trapped Degenerate Fermi GasesFeb 22 2001The structure and stability of dilute degenerate Fermi gases trapped in an external potential is discussed with special emphasis on the influence of s- and p-wave interactions. In a first step an Effective Contact Interaction for all partial waves is ... More
Stability of Trapped Ultracold Fermi Gases Using Effective s- and p-Wave Contact-InteractionsMar 15 2000Sep 15 2000The stability of trapped dilute Fermi gases against collapse towards large densities is studied. A hermitian effective contact-interaction for all partial waves is derived, which is particularly suited for a mean-field description of these systems. Including ... More
Rogosinski's lemma for univalent functions, hyperbolic Archimedean spirals and the Loewner equationNov 04 2013We describe the region $\mathcal{V}(z_0)$ of values of $f(z_0)$ for all normalized bounded univalent functions $f$ in the unit disk $\mathbb{D}$ at a fixed point $z_0 \in \mathbb{D}$. The proof is based on identifying $\mathcal{V}(z_0)$ as the reachable ... More
The Schramm-Loewner equation for multiple slitsNov 04 2013Jan 31 2014We prove that any disjoint union of finitely many simple curves in the upper half-plane can be generated in a unique way by the chordal multiple-slit Loewner equation with constant weights.
Copula Mixture Model for Dependency-seeking ClusteringJun 27 2012We introduce a copula mixture model to perform dependency-seeking clustering when co-occurring samples from different data sources are available. The model takes advantage of the great flexibility offered by the copulas framework to extend mixtures of ... More
Isometric immersions into manifolds with metallic structuresJun 29 2017We consider submanifolds into Riemannian manifold with metallic structures. We obtain some new results for hypersurfaces in these spaces and we express the fundamental theorem of submanifolds into products spaces in terms of metallic structures. Moreover, ... More
The Effect of Toroidal Magnetic Fields on Solar Oscillation FrequenciesJan 24 2018Solar oscillation frequencies change with the level of magnetic activity. Localizing subsurface magnetic field concentrations in the Sun with helioseismology will help us to understand the solar dynamo. Because the magnetic fields are not considered in ... More
Ion Acceleration - Target Normal Sheath AccelerationMay 30 2017Energetic ions have been observed since the very first laser-plasma experiments.Their origin was found to be the charge separation of electrons heated by thelaser, which transfers energy to the ions accelerated in the field. The adventof ultra-intense ... More
High-Energy Approximation of One-Loop Feynman IntegralsMay 28 1996We provide high-energy approximations for all one-loop scalar 3- and 4-point functions and the corresponding tensor integrals that appear in scattering processes with four external on-shell particles. Our expressions are valid if all kinematical invariants ... More
Unit Dependency Graph and its Application to Arithmetic Word Problem SolvingDec 03 2016Math word problems provide a natural abstraction to a range of natural language understanding problems that involve reasoning about quantities, such as interpreting election results, news about casualties, and the financial section of a newspaper. Units ... More