Results for "Lukas Simon"

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Stochastic Proximal Gradient Algorithms for Multi-Source Quantitative Photoacoustic TomographyJan 22 2018Feb 08 2018The development of accurate and efficient image reconstruction algorithms is a central aspect of quantitative photoacoustic tomography (QPAT). In this paper, we address this issues for multi-source QPAT using the radiative transfer equation (RTE) as accurate ... More
Towards Blockchain-based Auditable Storage and Sharing of IoT DataMay 22 2017Nov 14 2017Today the cloud plays a central role in storing, processing, and distributing data. Despite contributing to the rapid development of IoT applications, the current IoT cloud-centric architecture has led into a myriad of isolated data silos that hinders ... More
vh@nnlo-v2: New physics in Higgs StrahlungFeb 13 2018Introducing version 2 of the code vh@nnlo, we study the effects of a number of new-physics scenarios on the Higgs-Strahlung process. In particular, the cross section is evaluated within a general 2HDM and the MSSM. While the Drell-Yan-like contributions ... More
Analysis of the Linearized Problem of Quantitative Photoacoustic TomographyFeb 15 2017Quantitative image reconstruction in photoacoustic tomography requires the solution of a coupled physics inverse problem involvier light transport and acoustic wave propagation. In this paper we address this issue employing the radiative transfer equation ... More
Highly selective dry etching of GaP in the presence of Al$_\textrm{x}$Ga$_{1-\textrm{x}}$PJan 19 2018We present an inductively coupled-plasma reactive-ion etching process that simultaneously provides both a high etch rate and unprecedented selectivity for gallium phosphide (GaP) in the presence of aluminum gallium phosphide (Al$_\textrm{x}$Ga$_{1-\textrm{x}}$P). ... More
Self-organizing magnetic beads for biomedical applicationsOct 05 2011In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts ... More
The structure of DGA resolutions of monomial idealsOct 20 2016Let $I \subset k[x_1, \dotsc, x_n]$ be a squarefree monomial ideal a polynomial ring. In this paper we study multiplications on the minimal free resolution $\mathbb{F}$ of $S/I$. In particular, we characterize the possible vectors of total Betti numbers ... More
Stanley depth and simplicial spanning treesOct 14 2014Mar 09 2015We show that for proving the Stanley conjecture, it is sufficient to consider a very special class of monomial ideals. These ideals (or rather their lcm lattices) are in bijection with the simplicial spanning trees of skeletons of a simplex. We apply ... More
On the Complexity of SailsFeb 07 2011Dec 15 2011This paper analyses stable commutator length in groups Z^r * Z^s. We bound scl from above in terms of the reduced wordlength (sharply in the limit) and from below in terms of the answer to an associated subset-sum type problem. Combining both estimates, ... More
On eigenvalue and eigenvector estimates for nonnegative definite operatorsMar 16 2005In this article we further develop a perturbation approach to the Rayleigh--Ritz approximations from our earlier work. We both sharpen the estimates and extend the applicability of the theory to nonnegative definite operators . The perturbation argument ... More
Non-normal affine monoidsSep 27 2012Jun 07 2015We give a geometric description of the set of holes in a non-normal affine monoid $Q$. The set of holes turns out to be related to the non-trivial graded components of the local cohomology of $k[Q]$. From this, we see how various properties of $k[Q]$ ... More
A digit reversal property for Stern polynomialsOct 01 2016We consider the following polynomial generalization of Stern's diatomic series: let $s_1(x,y)=1$ and for $n\geq 1$ set $s_{2n}(x,y)=s_n(x,y)$ and $s_{2n+1}(x,y)=x\,s_n(x,y)+y\,s_{n+1}(x,y)$. The coefficient $[x^iy^j]s_n(x,y)$ is the number of hyperbinary ... More
Single-stage reconstruction algorithm for quantitative photoacoustic tomographyJan 19 2015Mar 25 2015The development of efficient and accurate image reconstruction algorithms is one of the cornerstones of computed tomography. Existing algorithms for quantitative photoacoustic tomography currently operate in a two-stage procedure: First an inverse source ... More
Combinatorial Reciprocity for Monotone TrianglesNov 11 2011The number of Monotone Triangles with bottom row k1 < k2 < ... < kn is given by a polynomial alpha(n; k1,...,kn) in n variables. The evaluation of this polynomial at weakly decreasing sequences k1 >= k2 >= ... >= kn turns out to be interpretable as signed ... More
The $v_n$-periodic Goodwillie tower on Wedges and CofibresDec 08 2016We introduce general methods to analyse the Goodwillie tower of the identity functor on a wedge $X \vee Y$ of spaces (using the Hilton-Milnor theorem) and on the cofibre $\mathrm{cof}(f)$ of a map $f: X \rightarrow Y$. We deduce some consequences for ... More
The Stanley Depth in the Upper Half of the Koszul ComplexAug 25 2014Nov 17 2014Let $R = K[X_1, ..., X_n]$ be a polynomial ring over some field $K$. In this paper, we prove that the $k$-th syzygy module of the residue class field $K$ of $R$ has Stanley depth $n-1$ for $\lfloor n/2 \rfloor \leq k < n$, as it had been conjectured by ... More
Valuations and Surface Area MeasuresOct 26 2014We consider valuations defined on polytopes containing the origin which have measures on the sphere as values. We show that the classical surface area measure is essentially the only such valuation which is SL(n) contravariant of degree one. Moreover, ... More
A Canonical module characterization of Serre's $(\mathrm{R}_1)$Jun 08 2015Jan 19 2016In this short note, we give a characterization of domains satisfying Serre's condition $(\mathrm{R}_1)$ in terms of their canonical modules. In the special case of toric rings, this generalizes a result of the second author (K. Yanagawa, Dualizing complexes ... More
Soft See-Saw: Radiative Origin of Neutrino Masses in SUSY TheoriesSep 23 2016Radiative neutrino mass generation within supersymmetric (SUSY) construction is studied. The mechanism is considered where the lepton number violation is originating from the soft SUSY breaking terms. This requires extensions of the MSSM with states around ... More
Kahler Potential for M-theory on a G_2 ManifoldMay 09 2003Nov 21 2003We compute the moduli Kahler potential for M-theory on a compact manifold of G_2 holonomy in a large radius approximation. Our method relies on an explicit G_2 structure with small torsion, its periods and the calculation of the approximate volume of ... More
A simple explicitly solvable interacting relativistic N-particle modelFeb 03 2015In this paper, we generalize a previous relativistic $1+1$-dimensional model for two mass-less Dirac particles with relativistic contact interactions to the $N$-particle case. Our model is based on the notion of a multi-time wave function which, according ... More
Centro-Affine Tensor ValuationsSep 13 2015We completely classify all measurable $\operatorname{SL}(n)$-covariant symmetric tensor valuations on convex polytopes containing the origin in their interiors. It is shown that essentially the only examples of such valuations are the moment tensor and ... More
On stable sl3-homology of torus knotsApr 02 2014The stable Khovanov-Rozansky homology of torus knots has been conjecturally described as the Koszul homology of an explicit non-regular sequence of polynomials. We verify this conjecture against newly available computational data for sl(3)-homology. Special ... More
On classical upper bounds for slice generaNov 08 2016We introduce a new link invariant called the algebraic genus, which gives an upper bound for the topological slice genus of links. In fact, the algebraic genus is an upper bound for another version of the slice genus proposed here: the minimal genus of ... More
The maximal order of hyper-($b$-ary)-expansionsNov 26 2015Using methods developed by Coons and Tyler, we give a new proof of a recent result of Defant, by determining the maximal order of the number of hyper-($b$-ary)-expansions of a nonnegative integer $n$ for general integral bases $b\geqslant 2$.
Moments and ValuationsJul 05 2015All measurable and $\operatorname{SL}(n)$-covariant vector valued valuations on convex polytopes containing the origin in their interiors are completely classified. The moment vector is shown to be essentially the only such valuation.
Rank Revealing Gaussian Elimination by the Maximum Volume ConceptFeb 08 2018A Gaussian elimination algorithm is presented that reveals the numerical rank of a matrix by yielding small entries in the Schur complement. The algorithm uses the maximum volume concept to find a square nonsingular submatrix of maximum dimension. The ... More
Design Considerations of Biaxially Tensile-Strained Germanium-on-Silicon LasersNov 18 2015Dec 14 2015Physical models of Ge energy band structure and material loss were implemented in LASTIP(TM), a 2D simulation tool for edge emitting laser diodes. The model calculation is able to match experimental data available. Important design parameters of a Fabry-Perot ... More
Gap control in phosphorene/BN structures from first principles calculationsJul 27 2016Using both DFT as well as $G_0W_0$ calculations, we investigate static and dynamic effects on the phosphorene band gap upon deposition and encapsulation on/in BN multilayers. We demonstrate how competing long- and short-range effects cause the phosphorene ... More
Comparison of models and lattice-gas simulations for Liesegang patternsMar 25 2008For more than a century Liesegang patterns -- self-organized, quasi-periodic structures occurring in diffusion-limited chemical reactions with two components -- have been attracting scientists. The pattern formation can be described by four basic empirical ... More
Phase diagram of electronic systems with quadratic Fermi nodes in $2<d<4$: $2+ε$ expansion, $4-ε$ expansion, and functional renormalization groupNov 14 2016Several materials in the regime of strong spin-orbit interaction such as HgTe, the pyrochlore iridate Pr$_2$Ir$_2$O$_7$, and the half-Heusler compound LaPtBi, as well as various systems related to these three prototype materials, are believed to host ... More
On Estimating Many Means, Selection Bias, and the BootstrapNov 15 2013With recent advances in high throughput technology, researchers often find themselves running a large number of hypothesis tests (thousands+) and esti- mating a large number of effect-sizes. Generally there is particular interest in those effects estimated ... More
Fast stray field computation on tensor gridsSep 27 2011Sep 30 2011A direct integration algorithm is described to compute the magnetostatic field and energy for given magnetization distributions on not necessarily uniform tensor grids. We use an analytically-based tensor approximation approach for function-related tensors, ... More
A tunable cancer cell filter using magnetic beads: cellular and fluid dynamic simulationsOct 05 2011In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts ... More
Topological Phases: An Expedition off LatticeFeb 01 2011Motivated by the goal to give the simplest possible microscopic foundation for a broad class of topological phases, we study quantum mechanical lattice models where the topology of the lattice is one of the dynamical variables. However, a fluctuating ... More
Centroid Velocity Statistics of Molecular CloudsOct 23 2014We compute structure functions and Fourier spectra of 2D centroid velocity (CV) maps in order to study the gas dynamics of typical molecular clouds (MCs) in numerical simulations. We account for a simplified treatment of time-dependent chemistry and the ... More
LaBonte's method revisited: An effective steepest descent method for micromagnetic energy minimizationSep 23 2013We present a steepest descent energy minimization scheme for micromagnetics. The method searches on a curve that lies on the sphere which keeps the magnitude of the magnetization vector constant. The step size is selected according to a modified Barzilai-Borwein ... More
Systemic risk through contagion in a core-periphery structured banking networkJun 25 2014We contribute to the understanding of how systemic risk arises in a network of credit-interlinked agents. Motivated by empirical studies we formulate a network model which, despite its simplicity, depicts the nature of interbank markets better than a ... More
CBinfer: Change-Based Inference for Convolutional Neural Networks on Video DataApr 14 2017Jun 21 2017Extracting per-frame features using convolutional neural networks for real-time processing of video data is currently mainly performed on powerful GPU-accelerated workstations and compute clusters. However, there are many applications such as smart surveillance ... More
Symmetry-protected topological invariant and Majorana impurity states in time-reversal-invariant superconductorsAug 12 2013Jun 02 2015We address the question of whether individual nonmagnetic impurities can induce zero-energy states in time-reversal-invariant topological superconductors, and define a class of symmetries which guarantee the existence of such states for a specific value ... More
Streamline integration as a method for two-dimensional elliptic grid generationOct 25 2016We propose a new numerical algorithm to construct a structured numerical grid of a doubly connected domain that is bounded by the contour lines of a given function. It is based on the integration of the streamlines of the two vector fields that form the ... More
Clustering of microscopic particles in constricted blood flowAug 22 2016A mixed suspension of red blood cells (RBCs) and microparticles flows through a cylindrical channel with a constriction mimicking a stenosed blood vessel. Our three-dimensional Lattice-Boltzmann simulations show that the RBCs are depleted right ahead ... More
Archetypal Analysis for Sparse Representation-based Hyperspectral Sub-pixel QuantificationFeb 08 2018The estimation of land cover fractions from remote sensing images is a frequently used indicator of the environmental quality. This paper focuses on the quantification of land cover fractions in an urban area of Berlin, Germany, using simulated hyperspectral ... More
Critical O(N) models above four dimensions: Small-N solutions and stabilityApr 12 2016We explore O(N) models in dimensions $4<d<6$. Specifically, we investigate models of an O(N) vector field coupled to an additional scalar field via a cubic interaction. Recent results in $d=6-\epsilon$ have uncovered an interacting ultraviolet fixed point ... More
Finding binomials in polynomial idealsJul 07 2016We describe an algorithm which finds binomials in a given ideal $I\subset\mathbb{Q}[x_1,\dots,x_n]$ and in particular decides whether binomials exist in $I$ at all. We demonstrate with several examples that binomials in polynomial ideals can be well hidden. ... More
Embedded desingularization for arithmetic surfaces -- toward a parallel implementationDec 21 2017We present an approach for algorithmic embedded desingularization of arithmetic surfaces bearing in mind implementability. Our algorithm is based on work by Cossart-Jannsen-Saito, though we present a variant using a refinement of the order instead of ... More
Quantum-phase synchronizationNov 13 2015We study mechanisms that allow one to synchronize the quantum phase of two qubits relative to a fixed basis. Starting from one qubit in a fixed reference state and the other in an unknown state, we find that contrary to the impossibility of perfect quantum ... More
An Abundance of Heterotic VacuaAug 15 2008Sep 17 2008We explicitly construct the largest dataset to date of heterotic vacua arising from stable vector bundles on Calabi-Yau threefolds. Focusing on elliptically fibered Calabi-Yau manifolds with spectral cover bundles, we show that the number of heterotic ... More
Coset construction of AdS particle dynamicsOct 26 2016Nov 07 2016We analyze dynamics of the AdS$_{N+1}$ particle realized on the coset SO$(2,N)/$SO$(1,N)$. Hamiltonian reduction provides the physical phase space in terms of the coadjoint orbit obtained by boosting a timelike element of ${\frak so}(2,N)$. We show equivalence ... More
Backscattering in helical edge states from a magnetic impurity and Rashba disorderFeb 27 2015Feb 06 2016Transport by helical edge states of a quantum spin Hall insulator is experimentally characterized by a weakly temperature-dependent mean free path of a few microns and by reproducible conductance oscillations, challenging proposed theoretical explanations. ... More
Antimargination of microparticles and platelets in the vicinity of branching vesselsJan 26 2018We investigate the margination of microparticles/platelets in blood flow through complex geometries typical for in vivo vessel networks: a vessel confluence and a bifurcation. Using 3D Lattice-Boltzmann simulations, we find that behind the confluence ... More
Using Deep Learning For Title-Based Semantic Subject Indexing To Reach Competitive Performance to Full-TextJan 20 2018For (semi-)automated subject indexing systems in digital libraries, it is often more practical to use metadata such as the title of a publication instead of the full-text or the abstract. Therefore, it is desirable to have good text mining and text classification ... More
A recursive approach to determine correlation functions in multi-baryon systemsJan 21 2013May 29 2013We propose a recursive algorithm for the calculation of multi-baryon correlation functions that combines the advantages of a recursive approach with those of the recently proposed unified contraction algorithm. The independent components of the correlators ... More
Non-perturbative vacua for M-theory on G2 manifoldsSep 24 2004We study moduli stabilization in the context of M-theory on compact manifolds with G2 holonomy, using superpotentials from flux and membrane instantons, and recent results for the Khaeler potential of such models. The existence of minima with negative ... More
Algorithmic Algebraic Geometry and Flux VacuaJun 14 2006We develop a new and efficient method to systematically analyse four dimensional effective supergravities which descend from flux compactifications. The issue of finding vacua of such systems, both supersymmetric and non-supersymmetric, is mapped into ... More
Reliable a-posteriori error estimators for $hp$-adaptive finite element approximations of eigenvalue/eigenvector problemsDec 02 2011We present reliable a-posteriori error estimates for $hp$-adaptive finite element approximations of eigenvalue/eigenvector problems. Starting from our earlier work on $h$ adaptive finite element approximations we show a way to obtain reliable and efficient ... More
Functional Renormalization Group Approach for Inhomogeneous One-Dimensional Fermi Systems with Finite-Ranged InteractionsSep 23 2016Jan 16 2017We introduce an equilibrium formulation of the functional renormalization group (fRG) for inhomogeneous systems capable of dealing with spatially finite-ranged interactions. In the general third order truncated form of fRG, the dependence of the two-particle ... More
Numerical analysis of lognormal diffusions on the sphereJan 11 2016Nov 01 2016Numerical solutions of stationary diffusion equations on the unit sphere with isotropic lognormal diffusion coefficients are considered. H\"older regularity in $L^p$ sense for isotropic Gaussian random fields is obtained and related to the regularity ... More
Effective Theories for Circuits and AutomataJun 28 2011Feb 20 2012Abstracting an effective theory from a complicated process is central to the study of complexity. Even when the underlying mechanisms are understood, or at least measurable, the presence of dissipation and irreversibility in biological, computational ... More
Volatility Swap Under the SABR ModelMar 25 2013The SABR model is shortly presented and the volatility swap explained. The fair value for a volatility swap is then computed using the usual theory in financial mathematics. An analytical solution using confluent hypergeometric functions is found. The ... More
One way cuts in oriented graphsDec 28 2007Nov 19 2010This paper has been withdrawn by the author.
(k+1)-sums versus k-sumsNov 19 2010Jun 08 2012A $k$-sum of a set $A\subseteq \mathbb{Z}$ is an integer that may be expressed as a sum of $k$ distinct elements of $A$. How large can the ratio of the number of $(k+1)$-sums to the number of $k$-sums be? Writing $k\wedge A$ for the set of $k$-sums of ... More
The Lattice Fermi SurfaceOct 08 2001The Nambu - Jona-Lasinio model in 2+1 dimensions is simulated for non-zero baryon chemical potential with a diquark source term. No evidence for a BCS condensate or gap is seen at high density; rather, critical behaviour with novel exponents is observed, ... More
Improving the Lattice QED ActionNov 24 1994Strongly coupled QED is a model whose physics is dominated by short-ranged effects. In order to assess which features of numerical simulations of the chiral phase transition are universal and which are not, we have formulated a quenched version of the ... More
Monte Carlo Study of the 3D Thirring ModelFeb 05 1997I review three different non-perturbative approaches to the three dimensional Thirring model: the 1/N_f expansion, Schwinger-Dyson equations, and Monte Carlo simulation. Simulation results are presented to support the existence of a non-perturbative fixed ... More
Nuts have no hairAug 18 1995We show that the Riemannian Kerr solutions are the only Riemannian, Ricci-flat and asymptotically flat ${\rm C}^{2}$-metrics $g_{\mu\nu}$ on a 4-dimensional complete manifold ${\cal M}$ of topology ${\rm R}^{2} \times {\rm S}^{2}$ which have (at least) ... More
Spreadsheet HellJan 21 2008This management paper looks at the real world issues faced by practitioners managing spreadsheets through the production phase of their life cycle. It draws on the commercial experience of several developers working with large corporations, either as ... More
A Galois-Connection between Cattell's and Szondi's Personality ProfilesMay 05 2014We propose a computable Galois-connection between, on the one hand, Cattell's 16-Personality-Factor (16PF) Profiles, one of the most comprehensive and widely-used personality measures for non-psychiatric populations and their containing PsychEval Personality ... More
Retrieving the three-dimensional matter power spectrum and galaxy biasing parameters from lensing tomographyFeb 09 2012Apr 16 2012With the availability of galaxy distance indicators in weak lensing surveys, lensing tomography can be harnessed to constrain the three-dimensional (3D) matter power spectrum over a range of redshift and physical scale. By combining galaxy-galaxy lensing ... More
On dp-minimal ordered structuresSep 23 2009We show some basic facts about dp-minimal ordered structures. The main results are : dp-minimal groups are abelian-by-finite-exponent, in a divisible ordered dp-minimal group, any infinite set has non-empty interior, and any theory of pure tree is dp-minimal. ... More
Finding generically stable measuresSep 18 2010We discuss two constructions for obtaining generically stable Keisler measures in an NIP theory. First, we show how to symmetrize an arbitrary invariant measure to obtain a generically stable one from it. Next, we show that suitable sigma-additive probability ... More
Restrictions of SL_3 Maass forms to maximal flat subspacesAug 04 2013Aug 26 2014Let \psi be a Hecke-Maass form on a cubic division algebra over \Q. We apply arithmetic amplification to improve the local bound for the L^2 norm of \psi restricted to maximal flat subspaces.
Constructive Gelfand duality for non-unital commutative C*-algebrasDec 05 2014Feb 03 2015We prove constructive versions of various usual results related to the Gelfand duality. Namely, that the constructive Gelfand duality extend to a duality between commutative nonunital C*-algebras and locally compact completely regular locales, that ideals ... More
Bend conductance of crossed wires in the presence of Andreev scatteringApr 12 1994We study the 4-probe bend conductance $G_{14,32}$ of a mesoscopic crossed wire structure in the ballistic regime in the absence of a magnetic field, which for normal devices is usually negative. We predict that for sufficiently large devices and for small ... More
How to determine a K3 surface from a finite automorphismApr 29 2016In this article we pursue the question when an automorphism determines a (complex) K3 surface up to isomorphism. We prove that if the automorphism is finite non-symplectic and the transcendental lattice small, then the isomorphism class of the K3 surface ... More
Global existence and convergence for a higher order flow in conformal geometryApr 22 2004We study a higher-order parabolic equation which generalizes the Ricci flow on two-dimensional surfaces. The metric is deformed conformally with a speed given by the Q-curvature of the metric. Under a condition on the Q-curvature of the initial metric ... More
Meromorphic Szego functions and asymptotic series for Verblunsky coefficientsFeb 23 2005We prove that the Szeg\H{o} function, $D(z)$, of a measure on the unit circle is entire meromorphic if and only if the Verblunsky coefficients have an asymptotic expansion in exponentials. We relate the positions of the poles of $D(z)^{-1}$ to the exponential ... More
Mass Equidistribution for Automorphic Forms of Cohomological Type on GL_2Jun 16 2010Aug 13 2010We extend Holowinsky and Soundararajan's proof of quantum unique ergodicity for holomorphic Hecke modular forms on SL(2,Z), by establishing it for automorphic forms of cohomological type on GL_2 over an arbitrary number field which satisfy the Ramanujan ... More
Quasi-modularity of generalized sum-of-divisors functionsJun 16 2015Jul 24 2015In 1919, P. A. MacMahon studied generating functions for generalized divisor sums. In this paper, we provide a framework in which to view these generating functions in terms of Jacobi forms, and prove that they are quasi-modular forms.
Introduction to Modular FormsJul 04 2014We introduce the notion of modular forms, focusing primarily on the group PSL2Z. We further introduce quasi-modular forms, as wel as discuss their relation to physics and their applications in a variety of enumerative problems. These notes are based on ... More
A limit theorem for moments in space of the increments of Brownian local timeJun 24 2015Dec 01 2015We proof a limit theorem for moments in space of the increments of Brownian local time. As special cases for the second and third moments, previous results by Chen et al. (Ann. Prob. 38, 2010, no. 1) and Rosen (Stoch. Dyn. 11, 2011, no. 1), which were ... More
Optimal Convergence Rates and One-Term Edgeworth Expansions for Multidimensional Functionals of Gaussian FieldsMay 28 2013Nov 11 2013We develop techniques for determining the exact asymptotic speed of convergence in the multidimensional normal approximation of smooth functions of Gaussian fields. As a by-product, our findings yield exact limits and often give rise to one-term generalized ... More
Tropical linear spaces and tropical convexityMay 08 2015In classical geometry, a linear space is a space that is closed under linear combinations. In tropical geometry, it has long been a consensus that tropical varieties defined by valuated matroids are the tropical analogue of linear spaces. It is not difficult ... More
An almost-integral universal Vassiliev invariant of knotsMay 23 2001Sep 05 2002A `total Chern class' invariant of knots is defined. This is a universal Vassiliev invariant which is integral `on the level of Lie algebras' but it is not expressible as an integer sum of diagrams. The construction is motivated by similarities between ... More
Curves between Lipschitz and $C^1$ and their relation to geometric knot theoryFeb 29 2016In this article we investigate regular curves whose derivatives have vanishing mean oscillations. We show that smoothing these curves using a standard mollifier one gets regular curves again. We apply this result to solve a couple of open problems. We ... More
Exceptional digit frequencies and expansions in non-integer basesNov 28 2017In this paper we study the set of digit frequencies that are realised by elements of the set of $\beta$-expansions. The main result of this paper demonstrates that as $\beta$ approaches $1,$ the set of digit frequencies that occur amongst the set of $\beta$-expansions ... More
Non-Gaussianities in a two-field generalization of Natural InflationNov 23 2017We describe a two-field model that generalizes Natural Inflation, in which the inflaton is the pseudo-Goldstone boson of an approximate symmetry that is spontaneously broken, and the radial mode is dynamical. We analyze how the dynamics fundamentally ... More
The Maser-Starburst connection in NGC253Nov 07 2017NGC253 is one of the closest starburst galaxies to the Milky Way and as such it has been studied in detail across the electromagnetic spectrum. Recent observations have detected the first extragalactic class I methanol masers at 36 and 44 GHz and the ... More
Numerical study of the $2+1d$ Thirring model with U($2N$)-invariant fermionsAug 25 2017In 2+1 dimensions the global U($2N$) symmetry associated with massless Dirac fermions is broken to U($N)\otimes$U($N$) by a parity-invariant mass. I will show how to adapt the domain wall formulation to recover the U($2N$)-invariant limit in interacting ... More
The Spectral Gap of Sparse Random DigraphsAug 01 2017The second largest eigenvalue of a transition matrix $P$ has connections with many properties of the underlying Markov chain, and especially its convergence rate towards the stationary distribution. In this paper, we give an asymptotic upper bound for ... More
A remark on the group-completion theoremSep 07 2017Suppose that $M$ is a topological monoid satisfying $\pi_0M=\mathbb{N}$ to which the McDuff-Segal group-completion theorem applies. This implies that a certain map $f: \mathbb{M}_{\infty}\rightarrow \Omega BM$ defined on an infinite mapping telescope ... More
Resolving the observer reference class problem in cosmologyJul 14 2017The assumption that we are typical observers plays a core role in attempts to make multiverse theories empirically testable. A widely shared worry about this assumption is that it suffers from systematic ambiguity concerning the reference class of observers ... More
On the Computation of the Shannon Capacity of a Discrete Channel with NoiseJan 30 2017Jan 31 2017Muroga [M52] showed how to express the Shannon channel capacity of a discrete channel with noise [S49] as an explicit function of the transition probabilities. His method accommodates channels with any finite number of input symbols, any finite number ... More
A heteroclinic orbit connecting traveling waves pertaining to different nonlinearitiesJun 13 2017In this paper we consider a semilinear parabolic equation in an infinite cylinder. The spatially varying nonlinearity is such that it connects two (spatially independent) bistable nonlinearities in a compact set in space. We prove that, given such a setting, ... More
Silicon Technologies for the CLIC Vertex DetectorJun 01 2017CLIC is a proposed linear e+e- collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics ... More
Kitaev MaterialsJan 24 2017In transition-metal compounds with partially filled $4d$ and $5d$ shells spin-orbit entanglement, electronic correlations, and crystal-field effects conspire to give rise to a variety of novel forms of topological quantum matter. This includes Kitaev ... More
Book to the Future - a manifesto for book liberationJul 04 2015The Book Liberation Manifesto is an exploration of publishing outside of current corporate constraints and beyond the confines of book piracy. We believe that knowledge should be in free circulation to benefit humankind, which means an equitable and vibrant ... More
Particle Dark EnergyNov 11 2004Feb 23 2006We explore the physics of a gas of particles interacting with a condensate that spontaneously breaks Lorentz invariance. The equation of state of this gas varies from 1/3 to less than -1 and can lead to the observed cosmic acceleration. The particles ... More
Splitting the Curvature of the Determinant Line BundleDec 21 1998It is shown that the determinant line bundle associated to a family of Dirac operators over a closed partitioned manifold has a canonical Hermitian metric with compatible connection whose curvature satisfies an additivity formula with contributions from ... More
Approximations of generating functions and a few conjecturesNov 25 2009This is a collection of 1031 formulas that were generated by a computer program in 1992. The set is the database of integer sequences as of 1992 which contained 4568 sequences. These sequences were later published in the Encyclopedia of Integer Sequences ... More