Results for "Michael Hanfland"

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High-pressure study of X-ray diffuse scattering in ferroelectric perovskitesJul 27 2007We present a high-pressure x-ray diffuse scattering study of the ABO$_3$ ferroelectric perovskites BaTiO_3 and KNbO_3. The well-known diffuse lines are observed in all the phases studied. In KNbO_3, we show that the lines are present up to 21.8 GPa, with ... More
Crystal structure of solid Oxygen at high pressure and low temperatureNov 21 2001Results of X-ray diffraction experiments on solid oxygen at low temperature and at pressures up to 10 GPa are presented.A careful sample preparation and annealing around 240 K allowed to obtain very good diffraction patterns in the orthorhombic delta-phase. ... More
Anisotropic compression in the high pressure regime of pure and Cr-doped vanadium dioxideOct 09 2011May 24 2012We present structural studies of V$_{1-x}$Cr$_x$O$_2$ (pure, 0.7% and 2.5% Cr doped) compounds at room temperature in a diamond anvil cell for pressures up to 20 GPa using synchrotron x-ray powder diffraction. All the samples studied show a persistence ... More
Observation of the Sb2S3-type post-post-GdFeO3-perovskite: A model structure for high density ABX3 and A2X3 phasesOct 10 2014Ten years have passed since the description of the perovskite to post-perovskite transition in MgSiO3 and its' impact on the mineralogy and rheology of the D" region at the base of the Earth's mantle. Much work has explored the mechanisms operating during ... More
Formation of transition metal hydrides at high pressuresJul 13 2009Silane (SiH4) is found to (partially) decompose at pressures above 50 GPa at room temperature into pure Si and H2. The released hydrogen reacts with surrounding metals in the diamond anvil cell to form metal hydrides. A formation of rhenium hydride is ... More
Jahn-Teller, polarity and insulator-to-metal transition in BiMnO3 at high pressureJun 25 2013Feb 20 2014The interaction of coexisting structural instabilities in multiferroic materials gives rise to intriguing coupling phenomena and extraordinarily rich phase diagrams, both in bulk materials and strained thin films. Here we investigate the multiferroic ... More
High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid perovskiteMay 11 2016In this paper we provide an accurate high-pressure structural and optical study of MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition towards an orthorhombic structure around 0.3 GPa followed by full amorphization of the ... More
Structural transformations of Li2C2 at high pressuresApr 26 2016Structural changes of Li2C2 under pressure were studied by synchrotron x-ray diffraction in a diamond anvil cell under hydrostatic conditions and by using evolutionary search methodology for crystal structure prediction. We show that the high-pressure ... More
Pressure induced Hydrogen-Hydrogen interaction in metallic FeH revealed by NMRFeb 08 2019Knowledge of the behavior of hydrogen in metal hydrides is the key for understanding their electronic properties. So far, no experimental methods exist to access these properties beyond 100 GPa, where high-Tc superconductivity emerges. Here, we present ... More
Symmetry preserving lattice collapse in tetragonal SrFe_(2-x)Ru_xAs_2 (x = 0, 0.2) -- a combined experimental and theoretical studyApr 27 2011In a joint experimental and theoretical study, we investigate the isostructural collapse from the ambient pressure tetragonal phase to a collapsed tetragonal phase for non-superconducting metallic SrFe2As2 and SrFe_1.8Ru_0.2As_2. The crystallographic ... More
Discovery of a superhard iron tetraboride superconductorApr 18 2013Single crystals of novel orthorhombic (space group Pnnm) iron tetraboride FeB4 were synthesised at pressures above 8 GPa and high temperatures. Magnetic susceptibility measurements demonstrated bulk superconductivity below 2.9 K. The putative isotope ... More
Deconfinement transition and dimensional crossover in the Bechgaard-Fabre salts: pressure- and temperature-dependent optical investigationsSep 25 2009The infrared response of the organic conductor (TMTSF)$_2$PF$_6$ and the Mott insulator (TMTTF)$_2$PF$_6$ are investigated as a function of temperature and pressure and for the polarization parallel and perpendicular to the molecular stacks. By applying ... More
Superconductivity in Weyl Semimetal Candidate MoTe2Aug 14 2015Mar 02 2016In recent years, layered transition-metal dichalcogenides (TMDs) have attracted considerable attention because of their rich physics; for example, these materials exhibit superconductivity, charge density waves, and the valley Hall effect. As a result, ... More
High-pressure synthesis of ultraincompressible hard rhenium nitride pernitride Re$_{2}$(N$_{2}$)N$_{2}$ stable at ambient conditionsFeb 25 2019Here we report the synthesis of metallic, ultraincompressible (bulk modulus $K_{0}$ = 428(10) GPa) and very hard (nanoindentation hardness 36.7(8) GPa) rhenium (V) nitride pernitride Re$_{2}$(N$_{2}$)N$_{2}$. While the empirical chemical formula of the ... More
Crystal structure of LaTiO_3.41 under pressureFeb 27 2004The crystal structure of the layered, perovskite-related LaTiO_3.41 (La_5Ti_5O_{17+\delta}) has been studied by synchrotron powder x-ray diffraction under hydrostatic pressure up to 27 GPa (T = 295 K). The ambient-pressure phase was found to remain stable ... More
Pressure-induced structural phase transition in the Bechgaard-Fabre saltsMay 28 2009The crystal structures of the quasi-one-dimensional organic salts (TMTTF)$_2$PF$_6$ and (TMTSF)$_2$PF$_6$ were studied by pressure-dependent x-ray diffraction up to 10 GPa at room temperature. The unit-cell parameters exhibit a clear anomaly due to a ... More
Structural investigations on $ε$-FeGe at high pressure and low temperatureMar 01 2007The structural parameters of $\epsilon$-FeGe have been determined at ambient conditions using single crystal refinement. Powder diffraction have been carried out to determine structural properties and compressibility for pressures up to 30 GPa and temperatures ... More
Pressure-driven orbital reorientation and change in Mott-Hubbard gap in YTiO3Apr 15 2005We investigate the crystal structure of YTiO3 at high pressures up to 30 GPa by synchrotron x-ray powder diffraction (T = 295 K). The variation of the Ti--O bond lengths with pressure evidences a distinct change in the distortion of the TiO_6 octahedra ... More
Plasmons in Sodium under Pressure: Increasing Departure from Nearly-Free-Electron BehaviorApr 18 2011We have measured plasmon energies in Na under high pressure up to 43 GPa using inelastic x-ray scattering (IXS). The momentum-resolved results show clear deviations, growing with increasing pressure, from the predictions for a nearly-free electron metal. ... More
Quantum and Classical Orientational Ordering in Solid HydrogenMay 14 1996Jan 17 1997We present a unified view of orientational ordering in phases I, II, and III of solid hydrogen. Phases II and III are orientationally ordered, while the ordering objects in phase II are angular momenta of rotating molecules, and in phase III the molecules ... More
Structural properties of the sesquicarbide superconductor La2C3 at high pressureMar 24 2005The effect of pressure on the structural properties of lanthanum sesquicarbide La2C3 (T_c = 13 K) has been investigated at room temperature by angle-dispersive powder x-ray diffraction in a diamond anvil cell. The compound remains in the cubic Pu2C3-type ... More
Superconducting and normal phases of FeSe single crystals at high pressureApr 11 2009May 12 2009We report on the synthesis of superconducting single crystals of FeSe, and their characterization by X-ray diffraction, magnetization and resistivity. We have performed ac susceptibility measurements under high pressure in a hydrostatic liquid argon medium ... More
CPT and Other Symmetries in String/M TheorySep 20 2004Feb 05 2005We initiate a search for non-perturbative consistency conditions in M theory. Some non-perturbative conditions are already known in Type I theories; we review these and search for others. We focus principally on possible anomalies in discrete symmetries. ... More
Linear programming methods for exponential dominationJan 19 2018For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1 \le \sum_{d \in D}$ $\left( \tfrac{1}{2} \right)^{dist(d,v) -1}$ for every $v \in V(G),$ where $dist(d,v)$ denotes the length of the shortest $dv$ path. The ... More
On exponential domination of the consecutive circulant graphDec 14 2017For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1\le \sum_{d \in D}$ $\left( \frac{1}{2} \right)^{\text{dist}(d,v) -1}$ for every $v \in V(G),$ where dist$(d,v)$ denotes the length of the smallest $dv$ path. ... More
An algorithm for quantifying dependence in multivariate data setsJul 04 2012Sep 27 2012We describe an algorithm to quantify dependence in a multivariate data set. The algorithm is able to identify any linear and non-linear dependence in the data set by performing a hypothesis test for two variables being independent. As a result we obtain ... More
Logic Programming with Graph Automorphism: Integrating naut with Prolog (Tool Description)Jul 17 2016Aug 01 2016This paper presents the plnauty~library, a Prolog interface to the nauty graph-automorphism tool. Adding the capabilities of nauty to Prolog combines the strength of the "generate and prune" approach that is commonly used in logic programming and constraint ... More
Slow Steady-Shear of Plastic Bead RaftsOct 12 2004Experimental measurements of the response of a two dimensional system of plastic beads subjected to steady shear are reported. The beads float at the surface of a fluid substrate and are subjected to a slow, steady-shear in a Couette geometry. The flow ... More
Asymmetric response of a jammed plastic bead raftMay 18 2006Fluctuation-dissipation relations have received significant attention as a potential method for defining an effective temperature in nonequilibrium systems. The successful development of an effective temperature would be an important step in the application ... More
Examples of nonpolygonal limit shapes in i.i.d. first-passage percolation and infinite coexistence in spatial growth modelsSep 13 2010Mar 13 2013We construct an edge-weight distribution for i.i.d. first-passage percolation on $\mathbb{Z}^2$ whose limit shape is not a polygon and whose extreme points are arbitrarily dense in the boundary. Consequently, the associated Richardson-type growth model ... More
Interface dynamics in discrete forward-backward diffusion equationsApr 05 2013We study the motion of phase interfaces in a diffusive lattice equation with bistable nonlinearity and derive a free boundary problem with hysteresis to describe the macroscopic evolution in the parabolic scaling limit. The first part of the paper deals ... More
Group analysis of differential equations and generalized functionsDec 28 1999We present an extension of the methods of classical Lie group analysis of differential equations to equations involving generalized functions (in particular: distributions). A suitable framework for such a generalization is provided by Colombeau's theory ... More
What the characters of irreducible subrepresentations of Jordan cells can tell us about LCFTJul 22 2013Jan 04 2014In this article, we review some aspects of logarithmic conformal field theories which can be inferred from the characters of irreducible submodules of indecomposable modules. We will mainly consider the W(2,2p-1,2p-1,2p-1) series of triplet algebras and ... More
A Worst-case Bound for Topology Computation of Algebraic CurvesApr 08 2011Computing the topology of an algebraic plane curve $\mathcal{C}$ means to compute a combinatorial graph that is isotopic to $\mathcal{C}$ and thus represents its topology in $\mathbb{R}^2$. We prove that, for a polynomial of degree $n$ with coefficients ... More
Comparison between step strains and slow steady shear in a bubble raftDec 20 2004We report on a comparison between stress relaxations after an applied step strain and stress relaxations during slow, continuous strain in a bubble raft. A bubble raft serves as a model two-dimensional foam and consists of a single layer of bubbles on ... More
Evaluation of Contactless Smartcard AntennasJul 23 2015This report summarizes the results of our evaluation of antennas of contactless and dual interface smartcards and our ideas for user-switchable NFC antennas. We show how to disassemble smartcards with contactless capabilities in order to obtain the bare ... More
A Variant of K-theory: K_{+-}Feb 11 2003We describe a variant of K-theory for spaces with involution, built from vector bundles which are sent to their negative under the involution.
The periodic Floer homology of a Dehn twistOct 04 2004May 02 2005The periodic Floer homology of a surface symplectomorphism, defined by the first author and M. Thaddeus, is the homology of a chain complex which is generated by certain unions of periodic orbits, and whose differential counts certain embedded pseudoholomorphic ... More
The role of blood circulatory system in thermal regulation of animals explained by entropy production analysisAug 16 2013A novel model of thermal regulation of homoeothermic animals has been implemented. The model is based on a non-equilibrium thermodynamic approach which introduces entropy balance and the rate of entropy generation as a formulation of The Second Law. The ... More
Hysteresis and phase transitions in a lattice regularization of an ill-posed forward-backward diffusion equationOct 18 2016We consider a lattice regularization for an ill-posed diffusion equation with trilinear constitutive law and study the dynamics of phase interfaces in the parabolic scaling limit. Our main result guarantees for a certain class of single-interface initial ... More
Stopping Active Learning based on Predicted Change of F Measure for Text ClassificationJan 26 2019During active learning, an effective stopping method allows users to limit the number of annotations, which is cost effective. In this paper, a new stopping method called Predicted Change of F Measure will be introduced that attempts to provide the users ... More
Hysteresis and phase transitions in a lattice regularization of an ill-posed forward-backward diffusion equationOct 18 2016Aug 06 2017We consider a lattice regularization for an ill-posed diffusion equation with trilinear constitutive law and study the dynamics of phase interfaces in the parabolic scaling limit. Our main result guarantees for a certain class of single-interface initial ... More
A note on Neumann problems on graphsMar 22 2018We discuss Neumann problems for self-adjoint Laplacians on (possibly infinite) graphs. Under the assumption that the heat semigroup is ultracontractive we discuss the unique solvability for non-empty subgraphs with respect to the vertex boundary and provide ... More
Open Mobile API: Accessing the UICC on Android DevicesJan 12 2016This report gives an overview of secure element integration into Android devices. It focuses on the Open Mobile API as an open interface to access secure elements from Android applications. The overall architecture of the Open Mobile API is described ... More
On Covert Acoustical Mesh Networks in AirJun 04 2014Covert channels can be used to circumvent system and network policies by establishing communications that have not been considered in the design of the computing system. We construct a covert channel between different computing systems that utilizes audio ... More
Root Refinement for Real PolynomialsApr 07 2011Jun 12 2013We consider the problem of approximating all real roots of a square-free polynomial $f$. Given isolating intervals, our algorithm refines each of them to a width of $2^{-L}$ or less, that is, each of the roots is approximated to $L$ bits after the binary ... More
A natural probability measure derived from Stern's diatomic sequenceJun 01 2017Mar 15 2018Stern's diatomic sequence with its intrinsic repetition and refinement structure between consecutive powers of $2$ gives rise to a rather natural probability measure on the unit interval. We construct this measure and show that it is purely singular continuous, ... More
Pressure-induced phase transitions and high-pressure tetragonal phase of Fe1.08TeSep 06 2012We report the effects of hydrostatic pressure on the temperature-induced phase transitions in Fe1.08Te in the pressure range 0-3 GPa using synchrotron powder x-ray diffraction (XRD). The results reveal a plethora of phase transitions. At ambient pressure, ... More
Renormalization of unicritical analytic circle mapsSep 23 2016In this paper we generalize renormalization theory for analytic critical circle maps with a cubic critical point to the case of maps with an arbitrary odd critical exponent by proving a quasiconformal rigidity statement for renormalizations of such maps. ... More
Introducing Molly: Distributed Memory Parallelization with LLVMSep 07 2014Programming for distributed memory machines has always been a tedious task, but necessary because compilers have not been sufficiently able to optimize for such machines themselves. Molly is an extension to the LLVM compiler toolchain that is able to ... More
Algorithmic Diversity for Software SecurityDec 13 2013Software diversity protects against a modern-day exploits such as code-reuse attacks. When an attacker designs a code-reuse attack on an example executable, it relies on replicating the target environment. With software diversity, the attacker cannot ... More
Recent reproducibility estimates indicate that negative evidence is observed over 30 times before publicationMay 19 2016Sep 12 2016The Open Science Collaboration recently reported that 36% of published findings from psychological studies were reproducible by independent researchers. We can use this information together with Bayes theorem to estimate the statistical power needed to ... More
Singular sets and parameters of generalized triangle orbifoldsMar 03 2001Aug 22 2001We study groups generated by three half-turns in Lobachevsky space and their factor-orbifolds. This generalized triangle groups are directly connected with the arbitrary 2-generator Kleinian groups. Our main result is a complete description of the singular ... More
Malliavin calculus method for asymptotic expansion of dual control problemsSep 28 2012Oct 14 2013We develop a technique based on Malliavin-Bismut calculus ideas, for asymptotic expansion of dual control problems arising in connection with exponential indifference valuation of claims, and with minimisation of relative entropy, in incomplete markets. ... More
Semi-static hedging for certain Margrabe type options with barriersOct 28 2008Feb 12 2010It turns out that in the bivariate Black-Scholes economy Margrabe type options exhibit symmetry properties leading to semi-static hedges of rather general barrier options. Some of the results are extended to variants obtained by means of Brownian subordination. ... More
Small product sets in compact groupsFeb 07 2014Jun 03 2016We show in this paper that a sub-critical pair $(A,B)$ of sufficiently "spread-out" Borel sets in a compact and second countable group $K$ with an \emph{abelian} identity component, must reduce to a Sturmian pair in either $\bT$ or $\bT \rtimes \{-1,1\}$. ... More
On the antiderivative of inverse functionsDec 12 2013Jun 05 2014One of the basics of calculus is the following proposition: If $F$ and $G$ are antiderivatives of two real functions $f$ and $g$ resp., then an antiderivative of $\lambda f+g$ is $\lambda F + G$. It may be surprising that such systematic an integration ... More
An asymptotic approach in Mahler's methodNov 24 2015Nov 25 2015We provide a general result for the algebraic independence of Mahler functions by a new method based on asymptotic analysis. As a consequence of our method, these results hold not only over $\mathbb{C}(z)$, but also over $\mathbb{C}(z)(\mathcal{M})$, ... More
Concordance of certain 3-braids and Gauss diagramsApr 14 2016Let $\beta:=\sigma_1\sigma_2^{-1}$ be a braid in $B_3$, where $B_3$ is the braid group on 3 strings and $\sigma_1, \sigma_2$ are the standard Artin generators. We use Gauss diagram formulas to show that for each natural number $n$ not divisible by $3$ ... More
Link invariants via counting surfacesSep 03 2012Nov 22 2013A Gauss diagram is a simple, combinatorial way to present a knot. It is known that any Vassiliev invariant may be obtained from a Gauss diagram formula that involves counting (with signs and multiplicities) subdiagrams of certain combinatorial types. ... More
On quasi-morphisms from knot and braid invariantsJul 15 2009Jul 02 2012We study quasi-morphisms on the groups Pn of pure braids on n strings and on the group D of compactly supported area-preserving diffeomorphisms of an open two-dimensional disc. We show that it is possible to build quasi-morphisms on Pn by using knot invariants ... More
Griffiths singularities and algebraic order in the exact solution of an Ising model on a fractal modular networkJan 15 2007Apr 12 2007We use an exact renormalization-group transformation to study the Ising model on a complex network composed of tightly-knit communities nested hierarchically with the fractal scaling recently discovered in a variety of real-world networks. Varying the ... More
Product set phenomena for measured groupsJun 02 2016Following the works of Furstenberg and Glasner on stationary means, we strengthen and extend in this paper some recent results by Di Nasso, Goldbring, Jin, Leth, Lupini and Mahlburg on piecewise syndeticity of product sets in countable \textsc{amenable} ... More
Speeding-Up Convergence via Sequential Subspace Optimization: Current State and Future DirectionsDec 31 2013This is an overview paper written in style of research proposal. In recent years we introduced a general framework for large-scale unconstrained optimization -- Sequential Subspace Optimization (SESOP) and demonstrated its usefulness for sparsity-based ... More
The Evening Tutoring Center at the United States Air Force AcademyFeb 09 2011The United States Air Force Academy (USAFA) has opened an Evening Tutoring Center to provide after-hours tutoring every evening before class days. The center focuses on first and second year courses in challenging quantitative disciplines: mathematics, ... More
pyro: A teaching code for computational astrophysical hydrodynamicsJun 28 2013Jun 12 2014We describe pyro: a simple, freely-available code to aid students in learning the computational hydrodynamics methods widely used in astrophysics. pyro is written with simplicity and learning in mind and intended to allow students to experiment with various ... More
Hilbert C*-modules over monotone complete C*-algebrasAug 31 1994Jul 27 2010The aim of the present paper is to describe self-duality and C*- reflexivity of Hilbert {\bf A}-modules $\cal M$ over monotone complete C*-algebras {\bf A} by the completeness of the unit ball of $\cal M$ with respect to two types of convergence being ... More
The primitive ontology of quantum physics: guidelines for an assessment of the proposalsJun 03 2014The paper seeks to make progress from stating primitive ontology theories of quantum physics, notably Bohmian mechanics, the GRW matter density theory and the GRW flash theory, to assessing these theories. Four criteria are set out: (a) internal coherence; ... More
Interest Rates and InflationApr 12 2011A relation between interest rates and inflation is presented using a two component economic model and a simple general principle. Preliminary results indicate a remarkable similarity to classical economic theories, in particular that of Wicksell.
The Cayley Trick for Tropical Hypersurfaces With a View Toward Ricardian EconomicsJun 29 2016The purpose of this survey is to summarize known results about tropical hypersurfaces and the Cayley Trick from polyhedral geometry. This allows for a systematic study of arrangements of tropical hypersurfaces and, in particular, arrangements of tropical ... More
Bounds on Integrals with Respect to Multivariate CopulasJun 28 2016Jun 30 2016Finding upper and lower bounds to integrals with respect to copulas is a quite prominent problem in applied probability. In their 2014 paper, Hofer and Iaco showed how particular two dimensional copulas are related to optimal solutions of the two dimensional ... More
Generalized Splines and Graphic ArrangementsJun 09 2016We define a chain complex for generalized splines on graphs, analogous to that introduced by Billera and refined by Schenck-Stillman for splines on polyhedral complexes. The hyperhomology of this chain complex yields bounds on the projective dimension ... More
Large deviations and rain showersJun 09 2015Rainfall from ice-free cumulus clouds requires collisions of large numbers of microscopic droplets to create every raindrop. The onset of rain showers can be surprisingly rapid, much faster than the mean time required for a single collision. Large-deviation ... More
Reply to Comment by M. Rohloff, T. Lapp and J. VollmerOct 25 2014This is a reply to a Comment on 'A test-tube model for rainfall', {\it Europhys. Lett.}, {\bf 106}, 40001, (2014).
Three Generative, Lexicalised Models for Statistical ParsingJun 17 1997In this paper we first propose a new statistical parsing model, which is a generative model of lexicalised context-free grammar. We then extend the model to include a probabilistic treatment of both subcategorisation and wh-movement. Results on Wall Street ... More
Syllable parsing in English and FrenchJun 02 1995In this paper I argue that Optimality Theory provides for an explanatory model of syllabic parsing in English and French. The argument is based on psycholinguistic facts that have been mysterious up to now. This argument is further buttressed by the computational ... More
The complexity of normal form rewrite sequences for AssociativityJun 20 1994Jun 20 1994The complexity of a particular term-rewrite system is considered: the rule of associativity (x*y)*z --> x*(y*z). Algorithms and exact calculations are given for the longest and shortest sequences of applications of --> that result in normal form (NF). ... More
A Computational Model of Syntactic Processing: Ambiguity Resolution from InterpretationJun 20 1994Syntactic ambiguity abounds in natural language, yet humans have no difficulty coping with it. In fact, the process of ambiguity resolution is almost always unconscious. But it is not infallible, however, as example 1 demonstrates. 1. The horse raced ... More
Free field construction for the eight-vertex model: representation for form factorsMar 18 2001Dec 06 2001The free field realization of the eight-vertex model is extended to form factors. It is achieved by constructing off-diagonal with respect to the ground state sectors matrix elements of the $\Lambda$ operator which establishes a relation between corner ... More
Long-range Fermi sea correlations as the resource for encoding quantum informationMay 14 2014An extra constant phase can be added to the wave function of a finite-length portion of a chiral Fermi sea. This phase can be read-out with the help of an imbalanced interferometer, where such a phase carrier interferes with the reference Fermi sea. As ... More
Half-levitons -- zero-energy excitations of a driven Fermi seaMar 15 2016A voltage pulse of a Lorentzian shape carrying a half of the flux quantum excites out of a zero-temperature Fermi sea an electron in a mixed state, which looks like a quasi-particle with an effectively fractional charge $e/2$. A prominent feature of such ... More
Toward the Graphics Turing Scale on a Blue Gene SupercomputerJan 09 2008We investigate raytracing performance that can be achieved on a class of Blue Gene supercomputers. We measure a 822 times speedup over a Pentium IV on a 6144 processor Blue Gene/L. We measure the computational performance as a function of number of processors ... More
Combinatorial Structure of Finite Dimensional Representations of Yangians: the Simply-Laced CaseNov 25 1996Mar 18 1997We compute the decomposition of representations of Yangians into g-modules for simply-laced Lie algebras g. The decomposition has an interesting combinatorial tree structure. Results depend on a conjecture of Kirillov and Reshetikhin.
Verbesserung von OS- und Service-Fingerprinting mittels FuzzingMar 03 2014Fingerprinting of services and operating systems is an essential part of penetration tests. In order to successfully penetrate the computing system's security measurements, preexisting fingerprinting methods are described and the paradigm of fingerprinting ... More
L^p Estimates for Maximal Averages Along One-variable Vector Fields in R^2Feb 01 2008We prove a conjecture of Lacey and Li in the case that the vector field depends only on one variable. Specifically: let v be a vector field defined on the unit square such that v(x,y) = (1,u(x)) for some measurable u from [0,1] to [0,1]. Fix a small parameter ... More
Kakeya Sets and Directional Maximal Operators in the PlaneMar 19 2007We completely characterize the boundedness of planar directional maximal operators on L^p. More precisely, if Omega is a set of directions, we show that M_Omega, the maximal operator associated to line segments in the directions Omega, is unbounded on ... More
Stable maps and singular curves on K3 surfacesJul 01 2015In this thesis we study singular curves on K3 surfaces. Let $\mathcal{B}_g$ denote the stack of polarised K3 surfaces of genus $g$ and set $p(g,k)=k^2(g-1)+1$. There is a stack $ \mathcal{T}^n_{g,k} \to \mathcal{B}_g$ with fibre over the polarised surface ... More
The Moduli of Singular Curves on K3 SurfacesJan 06 2014Mar 07 2015In this article we consider moduli properties of singular curves on K3 surfaces. Let $\mathcal{B}_g$ denote the stack of primitively polarized K3 surfaces $(X,L)$ of genus $g$ and let $\mathcal{T}^n_{g,k} \to \mathcal{B}_g$ be the stack parametrizing ... More
Beyond ECH capacitiesSep 04 2014Apr 04 2015ECH (embedded contact homology) capacities give obstructions to symplectically embedding one four-dimensional symplectic manifold with boundary into another. These obstructions are known to be sharp when the domain and target are ellipsoids (proved by ... More
Lecture notes on embedded contact homologyMar 22 2013Feb 06 2014These notes give an introduction to embedded contact homology (ECH) of contact three-manifolds, gathering together many basic notions which are scattered across a number of papers. We also discuss the origins of ECH, including various remarks and examples ... More
NJL-model analysis of dense quark matterFeb 23 2004Jan 27 2005Investigations of deconfined quark matter within NJL-type models are reviewed, focusing on the regime of low temperatures and ``moderate'' densities, which is not accessible by perturbative QCD. Central issue is the interplay between chiral symmetry restoration ... More
Assessment of the Effects of Azimuthal Mode Number Perturbations upon the Implosion Processes of Fluids in CylindersFeb 04 2016Fluid instabilities arise in a variety of contexts and are often unwanted results of engineering imperfections. In one particular model for a magnetized target fusion reactor, a pressure wave is propagated in a cylindrical annulus comprised of a dense ... More
Glycol-Water Interactions and co-existing phases and Temperature Dependent Solubility. An Example Of Carbon-Hydrogen Chemistry In WaterOct 26 2010Recently there has been great interest in Glycol-Water chemistry and solubility and temperature dependent phase dynamics. The Glycol-Water biochemistry of interactions is present in plant biology and chemistry, is of great interest to chemical engineers ... More
On a problem of NeumannSep 22 2015Oct 20 2015A conjecture widely attributed to Neumann is that all finite non-desarguesian projective planes contain a Fano subplane. In this note, we show that any finite projective plane of even order which admits an orthogonal polarity contains a Fano subplane. ... More
Effective T-odd P-even hadronic interactions from quark modelsMay 13 1996Tests of time reversal symmetry at low and medium energies may be analyzed in the framework of effective hadronic interactions. Here, we consider the quark structure of hadrons to make a connection to the more fundamental degrees of freedom. It turns ... More
Light-front field theory of hot and dense quark matterOct 01 2004Extending the concepts of light-front field theory to quantum statistics provides a novel approach towards nuclear matter under extreme conditions. Such conditions exist, e.g., in neutron stars or in the early stage of our universe. They are experimentally ... More
How often is a permutation an n'th power?Dec 03 1997We give a short argument that for any fixed n, the probability that a permutation on m letters is an n'th power is asymptotically C m^{phi(n)/n - 1}.
Calculating two- and three-body decays with FeynArts and FormCalcOct 30 2002The Feynman diagram generator FeynArts and the computer algebra program FormCalc allow for an automatic computation of 2->2 and 2->3 scattering processes in High Energy Physics. We have extended this package by four new kinematical routines and adapted ... More
J/Psi production in direct and resolved gamma gamma collisionsOct 09 2002The production of J/Psi mesons in gamma gamma collisions allows for a test of factorization in color-octet processes as predicted by NRQCD and observed at the Tevatron. We calculate the cross sections for J/Psi production with direct and resolved photons, ... More
When Newton meets Descartes: A Simple and Fast Algorithm to Isolate the Real Roots of a PolynomialSep 28 2011We introduce a new algorithm denoted DSC2 to isolate the real roots of a univariate square-free polynomial f with integer coefficients. The algorithm iteratively subdivides an initial interval which is known to contain all real roots of f. The main novelty ... More