Results for "Rob Gontrum"

total 1119took 0.11s
High-contrast Imager for Complex Aperture Telescopes (HiCAT): 6. Software Control Infrastructure and CalibrationMar 07 2019High contrast imaging using coronagraphy is one of the main avenues to enable the search for life on extrasolar Earth analogs. The HiCAT testbed aims to demonstrate coronagraphy and wavefront control for segmented on-axis space telescopes as envisioned ... More
Thermodynamics of Inozemtsev's Elliptic Spin ChainFeb 16 2016Apr 11 2016We study the thermodynamic behaviour of Inozemtsev's long-range elliptic spin chain using the Bethe ansatz equations describing the spectrum of the model in the infinite-length limit. We classify all solutions of these equations in that limit and argue ... More
Revenge of the Bell Heads: How the Net Heads Lost Control of the InternetSep 19 2001A dichotomy in regulatory treatment and corporate cultures exists between Internet Service Providers (ISPs) and telecommunication carriers. Telephone company executives (Bell Heads) may resent regulation, but they accept their fate and work creatively ... More
High energy astrophysics with the next generation of radio astronomy facilitiesOct 06 2008High energy astrophysics has made good use of combined high energy (X-ray, gamma-ray) and radio observations to uncover connections between outbursts, accretion, particle acceleration and kinetic feedback to the local ambient medium. In the field of microquasars ... More
Phenomenological aspects of supergravity theories in de Sitter vacuaAug 31 2016We introduce an $N=1$ supergravity model based on the gauged shift symmetry of a single chiral multiplet, which can be identified with the string dilaton or a compactification modulus. The model allows for a tunably small and positive value of the cosmological ... More
Independent Experimentation on the Activation of Deuterium-Loaded Materials by X-Ray ExposureSep 06 2017In an attempt to replicate work performed elsewhere [1], we have searched for x-ray induced nuclear activation of deuterated materials. Our first results, reported in September 2015, showed no evidence of nuclear activation, contrary to the results reported ... More
Order polaritiesJan 15 2019We define an order polarity to be a polarity $(X,Y,R)$ where $X$ and $Y$ are partially ordered, and we define an extension polarity to be a triple $(e_X,e_Y,R)$ such that $e_X:P\to X$ and $e_Y:P\to Y$ are poset extensions and $(X,Y,R)$ is an order polarity. ... More
Stable concordance of knots in 3-manifoldsDec 26 2008Knots and links in 3-manifolds are studied by applying intersection invariants to singular concordances. The resulting link invariants generalize the Arf invariant, the mod 2 Sato-Levine invariants, and Milnor's triple linking numbers. Besides fitting ... More
Contributions of effective theories with linearly realized and strongly interacting Higgs sectors to the process $e^+e^- \to W^+W^-$Jan 12 1996Previous form-factor-based analyses of $e^+e^-\to W^+W^-$ have focused upon non-standard contributions to the $WWZ$ and $WW\gamma$ vertices. A more complete form-factor-based formalism is presented which allows for more general corrections, including ... More
No finite axiomatizations for posets embeddable into distributive latticesOct 04 2016Nov 17 2017Let $m$ and $n$ be cardinals with $3\leq m,n\leq\omega$. We show that the class of posets that can be embedded into a distributive lattice via a map preserving all existing meets and joins with cardinalities strictly less than $m$ and $n$ respectively ... More
Finiteness properties of congruence classes of infinite matricesNov 03 2014We look at spaces of infinite-by-infinite matrices, and consider closed subsets that are stable under simultaneous row and column operations. We prove that up to symmetry, any of these closed subsets is defined by finitely many equations.
Data engineering for archive evolutionOct 13 2014From the moment astronomical observations are made the resulting data products begin to grow stale. Even if perfect binary copies are preserved through repeated timely migration to more robust storage media, data standards evolve and new tools are created ... More
The Modal Interpretation of Algebraic Quantum Field TheoryMar 04 2000In a recent article, Dieks has proposed a way to implement the modal interpretation of (nonrelativistic) quantum theory in relativistic quantum field theory. We show that his proposal fails to yield a well-defined prescription for which observables in ... More
Structure and asymptotics for Motzkin numbers modulo small primes using automataDec 24 2016We establish the asymptotic density and some structure results for the Motzkin numbers modulo primes up to 29 using automata.
Asymptotic density of Motzkin numbers modulo small primesNov 15 2016Dec 24 2016We establish the asymptotic density of the Motzkin numbers modulo small primes.
Asymptotic density of Catalan numbers modulo 3 and powers of 2Nov 11 2016Dec 24 2016We establish the asymptotic density of the Catalan numbers modulo 3 and modulo powers of 2.
Recursive axiomatizations for representable posetsJun 21 2018Jan 31 2019We use model theoretic techniques to construct explicit first-order axiomatizations for the classes of posets that can be represented as systems of sets, where the order relation is given by inclusion, and existing meets and joins of specified countable ... More
On Thickness and Packing Density for Knots and LinksMar 28 2002We describe some problems, observations, and conjectures concerning thickness and packing density of knots and links in $\sp^3$ and $\R^3$. We prove the thickness of a nontrivial knot or link in $\sp^3$ is no more than $\frac{\pi}{4}$, the thickness of ... More
Jets from X-ray binariesMar 14 2003Aug 28 2003Relativistic outflows, or `Jets', represent one of the most obvious, important and yet poorly-explained phenomena associated with accreting relativistic objects, including X-ray binaries. In the past decade we have observed highly relativistic flows, ... More
Relativistic Jets from X-ray binariesJul 05 1999In this review I summarise the status of observational research into relativistic jets from X-ray binaries, highlighting four areas in particular: (i) How relativistic are the jets ?, (ii) The disc : jet coupling, (iii) the nature of the underlying flat ... More
Searching for a gigamaser in APM08279+5255, and other short storiesMar 28 2006May 04 2006Bolometer arrays on large antennas at high, dry sites have unveiled a dusty population of massive, luminous galaxies - submillimetre galaxies, or SMGs - which make a significant contribution to the star-formation rate density at z > 1. The most crucial ... More
Non-elementary classes of representable posetsJul 18 2016A poset is $(\omega,C)$-representable if it can be embedded into a field of sets in such a way that all existing joins, and all existing \emph{finite} meets are preserved. We show that the class of $(\omega,C)$-representable posets cannot be axiomatized ... More
Closure operators, frames, and neatest representationsFeb 08 2017Nov 17 2017Given a poset $P$ and a standard closure operator $\Gamma:\wp(P)\to\wp(P)$ we give a necessary and sufficient condition for the lattice of $\Gamma$-closed sets of $\wp(P)$ to be a frame in terms of the recursive construction of the $\Gamma$-closure of ... More
Whitney towers and gropes in 4--manifoldsOct 20 2003Feb 17 2012Many open problems and important theorems in low-dimensional topology have been formulated as statements about certain 2--complexes called gropes. This paper describes a precise correspondence between embedded gropes in 4--manifolds and the failure of ... More
Structure and asymptotics for Motzkin numbers modulo primes using automataMar 02 2017We establish a lower bound of 2/p(p-1) for the asymptotic density of the Motzkin numbers divisible by a general prime number p > 3. We provide a criteria for when this asymptotic density is actually 1. We also provide a partial characterisation of those ... More
The Catalan numbers have no forbidden residue modulo primesMar 08 2017Let $C_n$ be the $n$th Catalan number. For any prime $p \geq 5$ we show that the set $\{C_n : n \in \mathbb{N} \}$ contains all residues mod $p$. In addition all residues are attained infinitely often. Any positive integer can be expressed as the product ... More
No finite axiomatizations for posets embeddable into distributive latticesOct 04 2016Oct 06 2016Let $m$ and $n$ be cardinals with $3\leq m,n\leq\omega$. We show that the class of posets that can be embedded into a distributive lattice via a map preserving all existing meets and joins with cardinalities strictly less than $m$ and $n$ respectively ... More
MAXI, LOFAR and Microquasars - All-sky monitoring of X-ray binaries in X-rays and radioOct 06 2008In this paper I will discuss future synergies between the Japanese MAXI X-ray all-sky monitor, to be placed on the International Space Station in 2009, and the next-generation radio astronomy array LOFAR, currently under construction in The Netherlands. ... More
Relativistic outflows from X-ray binaries (a.k.a. `Microquasars')Sep 27 2001In this review I summarise the observational connections between accretion and relativistic outflows -- jets -- in X-ray binaries. I argue that jets are likely to be a fairly ubiquitous property of X-ray binaries as a whole, an assertion which can be ... More
Microquasars: hard X-ray/gamma-ray emissionJan 15 2001I review some of the basic observational details of jets from X-ray binaries, or `microquasars'. It is shown that in both (Z and Atoll) NS and BHC systems radio emission, and therefore jet formation, is correlated with the presence of hard (30-500 keV) ... More
Energetics of jets from X-ray binariesOct 30 2000I discuss the energetics of synchrotron-emitting outflows, increasingly found to be present in many different classes of X-ray binary systems. It is shown that the outflow is likely to be comparable in power to the integrated X-ray luminosity, traditionally ... More
Membranes by the NumbersMar 06 2017Many of the most important processes in cells take place on and across membranes. With the rise of an impressive array of powerful quantitative methods for characterizing these membranes, it is an opportune time to reflect on the structure and function ... More
A comparison of the non-standard effects of effective theories with linearly realized and strongly interacting Higgs sectorsJan 12 1996Effective theories provide a powerful tool for testing the Standard Model and for searching for the effects of new physics in a model-independent manner. In general one assumes that the effects of new physics characterized by a high-energy scale may be ... More
Representing numbers as the sum of squares and powers in the ring $\mathbb{Z}_n$Aug 13 2017Sep 23 2017We examine the representation of numbers as the sum of two squares in $\mathbb{Z}_n$ for a general positive integer $n$. Using this information we make some comments about the density of positive integers which can be represented as the sum of two squares ... More
Weyl Asymptotics for Perturbations of Morse Potential and Connections to the Riemann Zeta FunctionNov 12 2018Let $N(T;V)$ denote the number of eigenvalues of the Schr\"odinger operator $-y'' + Vy$ with absolute value less than $T$. This paper studies the Weyl asymptotics of perturbations of the Schr\"odinger operator $-y'' + \frac{1}{4}e^{2t}y$ on $[x_0,\infty)$. ... More
Akbulut's corks and h-cobordisms of smooth simply connected 4-manifoldsDec 04 1997This is primarily an exposition, combining work of several authors (Curtis, Hsiang, Freedman, Stong, Matveyev, and Bizaca), of the proof that a smooth 5-dimensional h-cobordism between simply connected 4-manifolds is a product off of a contractible piece ... More
Circularly polarised radio emission from GRS 1915+105 and other X-ray binariesJun 10 2003I report the detection of circular polarisation, associated with relativistic ejections, from the `microquasar' GRS 1915+105. I further compare detections and limits of circular polarisation and circular-to-linear polarisation ratios in other X-ray binaries. ... More
Algebraic linking numbers of knots in 3-manifoldsFeb 04 2002Oct 04 2003Relative self-linking and linking "numbers" for pairs of knots in oriented 3-manifolds are defined in terms of intersection invariants of immersed surfaces in 4-manifolds. The resulting concordance invariants generalize the usual homological notion of ... More
Shedding light on the dark side of galaxy formation: submillimetre surveys through lensing clustersJul 12 2000Most new sub-mm/mm surveys, both deep and shallow, are being targeted at rich cluster fields. I explain why, comparing surveys that have exploited weak lensing by massive foreground clusters with those done in blank fields.
Asymptotic density of Motzkin numbers modulo small primesNov 15 2016We establish the asymptotic density of the Motzkin numbers modulo small primes.
Complementarity between Position and Momentum as a Consequence of Kochen-Specker ArgumentsDec 26 1999We give two simple Kochen-Specker arguments for complementary between the position and momentum components of spinless particles, arguments that are identical in structure to those given by Peres and Mermin for spin-1/2 particles.
Beables in Algebraic Quantum MechanicsNov 09 1997John Bell once argued that one ought to select, out of the 'observables' of quantum theory, some subset of 'beables' that can be consistently ascribed determinate values. Moreover, this subset should be selected so as to guarantee (among other things) ... More
Asymptotic density of Catalan numbers modulo 3 and powers of 2Nov 11 2016We establish the asymptotic density of the Catalan numbers modulo 3 and modulo powers of 2.
Conformal Structures and Necksizes of Embedded Constant Mean Curvature SurfacesJul 19 2002Let M = M_{g,k} denote the space of properly (Alexandrov) embedded constant mean curvature (CMC) surfaces of genus g with k (labeled) ends, modulo rigid motions, endowed with the real analytic structure described in [kmp]. Let $P = P_{g,k} = r_{g,k} \times ... More
Categories of frame-completions and join-specificationsJun 02 2018Given a poset $P$, a join-specification $\mathcal U$ for $P$ is a set of subsets of $P$ whose joins are all defined. The set $\mathcal I_{\mathcal U}$ of downsets closed under joins of sets in $\mathcal U$ forms a complete lattice, and is, in a sense, ... More
The decision problem for normed spaces over any class of ordered fieldsApr 17 2011May 01 2011It is known that the theory of any class of normed spaces over the reals that includes all spaces of a given dimension d > 1 is undecidable, and indeed, admits a relative interpretation of second-order arithmetic. The notion of a normed space makes sense ... More
Structure and asymptotics for Catalan numbers modulo primes using automataJan 11 2017Let $C_n$ be the $n$th Catalan number. We show that the asymptotic density of the set $\{n: C_n \equiv 0 \mod p \}$ is $1$ for all primes $p$, We also show that if $n = p^k -1$ then $C_n \equiv -1 \mod p$. Finally we show that if $n \equiv \{ \frac{p+1}{2}, ... More
Representable posetsMar 16 2016Aug 30 2016A poset is representable if it can be embedded in a field of sets in such a way that existing finite meets and joins become intersections and unions respectively (we say finite meets and joins are preserved). More generally, for cardinals $\alpha$ and ... More
Non-elementary classes of representable posetsJul 18 2016Apr 12 2017A poset is $(\omega,C)$-representable if it can be embedded into a field of sets in such a way that all existing joins, and all existing \emph{finite} meets are preserved. We show that the class of $(\omega,C)$-representable posets cannot be axiomatized ... More
Unit Groups of Representation Rings and their Ghost Rings as Inflation FunctorsNov 02 2016The theory of biset functors developed by Serge Bouc has been instrumental in the study of the unit group of the Burnside ring of a finite group, in particular for the case of p-groups. The ghost ring of the Burnside ring defines an inflation functor, ... More
Structure Preserving Bisimilarity, Supporting an Operational Petri Net Semantics of CCSPSep 19 2015In 1987 Ernst-R\"udiger Olderog provided an operational Petri net semantics for a subset of CCSP, the union of Milner's CCS and Hoare's CSP. It assigns to each process term in the subset a labelled, safe place/transition net. To demonstrate the correctness ... More
Asymmetric DiffusionDec 22 2004Sep 14 2005Diffusion rates through a membrane can be asymmetric, if the diffusing particles are spatially extended and the pores in the membrane have asymmetric structure. This phenomenon is demonstrated here via a deterministic simulation of a two-species hard-disk ... More
Quantum Communication TechnologyJul 23 2010Quantum communication is built on a set of disruptive concepts and technologies. It is driven by fascinating physics and by promising applications. It requires a new mix of competencies, from telecom engineering to theoretical physics, from theoretical ... More
Accretion modes and jet production in black hole X-ray binariesSep 07 2005We review our current understanding of the radio properties of black hole X-ray binaries in connection with the X-ray spectral states, and discuss them in the framework of the recently proposed unified model for the jet-accretion coupling in these systems. ... More
Entropy Bumps and Another Sufficient Condition for the Two--Weight Boundedness of Sparse OperatorsSep 26 2016In this short note, we give a very efficient proof of a recent result of Treil-Volberg and Lacey--Spencer giving sufficient conditions for the two-weight boundedness of a sparse operator. We also give a new sufficient condition for the two-weight boundedness ... More
Low Energy INTEGRAL Positrons from eXciting Dark MatterSep 17 2011The origin of the e^+e^- 511 keV line observed by INTEGRAL remains unclear. The rate and morphology of the signal have prompted questions as to whether dark matter could play a role. We explore the case of dark matter upscattering in the framework of ... More
Gauged R-symmetry and de Sitter vacua in supergravity and string theoryMar 06 2014Apr 20 2016A new class of metastable de Sitter vacua is presented and analyzed in N =1 supergravity and string theory with tunable (infinitesimally small) value of the cosmological constant. They are based on a gauged R-symmetry and the minimal spectrum contains ... More
The Spinor Representation of Surfaces in SpaceOct 08 1996The spinor representation is developed for conformal immersions of Riemann surfaces into space. We adapt the approach of Dennis Sullivan, which treats a spin structure on a Riemann surface M as a complex line bundle S whose square is the canonical line ... More
Membrane-protein interactions in mechanosensitive channelsJun 09 2004In this paper, we examine the mechanical role of the lipid bilayer in ion channel conformation and function with specific reference to the case of the mechanosensitive channel of large conductance (MscL). In a recent paper (Wiggins and Phillips, 2004), ... More
Whitney towers and the Kontsevich integralJan 30 2004Sep 28 2004We continue to develop an obstruction theory for embedding 2-spheres into 4-manifolds in terms of Whitney towers. The proposed intersection invariants take values in certain graded abelian groups generated by labelled trivalent trees, and with relations ... More
Prediction and outlier detection: a distribution-free prediction set with a balanced objectiveMay 10 2019May 14 2019We consider the multi-class classification problem when the training data and the out-of-sample test data may have different distributions and propose a method called BCOPS (balanced and conformal optimized prediction set) that constructs a prediction ... More
Representing integers as linear combinations of power productsJan 19 2012Let P be a finite set of at least two prime numbers, and A the set of positive integers that are products of powers of primes from P. Let F(k) denote the smallest positive integer which cannot be presented as sum of less than k terms of A. In a recent ... More
A Graph-Theoretic Approach to Efficient Voice-LeadingFeb 09 2016We study the Neo-Riemannian principle of parsimonious voice-leading using tools and techniques from classical graph theory and the modern field of complex networks. We quantify the relative importance of particular chords within this framework. The graph-theoretic ... More
The Import and Export of Cognitive ScienceNov 18 2009From its inception, a large part of the motivation for Cognitive Science has been the need for an interdisciplinary journal for the study of minds and intelligent systems. One threat to the interdisciplinarity of Cognitive Science, both the field and ... More
Stellar Mass Black Holes and Ultraluminous X-Ray SourcesAug 06 2012We review the likely population, observational properties, and broad implications of stellar-mass black holes and ultraluminous x-ray sources. We focus on the clear empirical rules connecting accretion and outflow that have been established for stellar-mass ... More
A one-sided power sum inequalityJul 27 2011Nov 06 2012In this note we prove results of the following types. Let be given distinct complex numbers $z_j$ satisfying the conditions $|z_j| = 1, z_j \not= 1$ for $j=1,..., n$ and for every $z_j$ there exists an $ i$ such that $z_i = \bar{z_j}. $ Then $$\inf_{k} ... More
FIRI - a Far-Infrared InterferometerJul 12 2007Half of the energy ever emitted by stars and accreting objects comes to us in the FIR waveband and has yet to be properly explored. We propose a powerful Far-InfraRed Interferometer mission, FIRI, to carry out high-resolution imaging spectroscopy in the ... More
Discriminant Analysis with Adaptively Pooled CovarianceNov 07 2011Dec 06 2011Linear and Quadratic Discriminant analysis (LDA/QDA) are common tools for classification problems. For these methods we assume observations are normally distributed within group. We estimate a mean and covariance matrix for each group and classify using ... More
Are Rindler Quanta Real? Inequivalent particle concepts in quantum field theoryAug 05 2000Philosophical reflection on quantum field theory has tended to focus on how it revises our conception of what a particle is. However, there has been relatively little discussion of the threat to the "reality" of particles posed by the possibility of inequivalent ... More
Generic Bell correlation between arbitrary local algebras in quantum field theorySep 12 1999Jan 08 2000We prove that for any two commuting von Neumann algebras of infinite type, the open set of Bell correlated states for the two algebras is norm dense. We then apply this result to algebraic quantum field theory -- where all local algebras are of infinite ... More
Quantum CommunicationMar 27 2007Quantum communication, and indeed quantum information in general, has changed the way we think about quantum physics. In 1984 and 1991, the first protocol for quantum cryptography and the first application of quantum non-locality, respectively, attracted ... More
The Poincaré-Hopf Theorem for relative braid classesApr 03 2012Braid Floer homology is an invariant of proper relative braid classes. Closed integral curves of 1-periodic Hamiltonian vector fields on the 2-disc may be regarded as braids. If the Braid Floer homology of associated proper relative braid classes is non-trivial, ... More
Gauging MSSM global symmetries and SUSY breaking in de Sitter vacuumNov 13 2015We elaborate on a recent study of a model of supersymmetry breaking we proposed recently, in the presence of a tunable positive cosmological constant, based on a gauged shift symmetry of a string modulus, external to the Standard Model (SM) sector. Here, ... More
Not Just a Matter of Time: Field Differences and the Shaping of Electronic Media in Supporting Scientific CommunicationSep 07 1999Apr 29 2000The shift towards the use of electronic media in scholarly communication appears to be an inescapable imperative. However, these shifts are uneven, both with respect to field and with respect to the form of communication. Different scientific fields have ... More
Monod-Wyman-Changeux Analysis of Ligand-Gated Ion Channel MutantsJan 22 2017We present a framework for computing the gating properties of ligand-gated ion channel mutants using the Monod-Wyman-Changeux (MWC) model of allostery. We derive simple analytic formulas for key functional properties such as the leakiness, dynamic range, ... More
On Affine Logic and Łukasiewicz LogicApr 02 2014Aug 14 2014The multi-valued logic of {\L}ukasiewicz is a substructural logic that has been widely studied and has many interesting properties. It is classical, in the sense that it admits the axiom schema of double negation, [DNE]. However, our understanding of ... More
A Curry-Howard Correspondence for the Minimal Fragment of Łukasiewicz LogicSep 12 2018In this paper we introduce a term calculus ${\cal B}$ which adds to the affine $\lambda$-calculus with pairing a new construct allowing for a restricted form of contraction. We obtain a Curry-Howard correspondence between ${\cal B}$ and the sub-structural ... More
Mutual Information based labelling and comparing clustersFeb 27 2017After a clustering solution is generated automatically, labelling these clusters becomes important to help understanding the results. In this paper, we propose to use a Mutual Information based method to label clusters of journal articles. Topical terms ... More
The radio spectrum of a quiescent stellar mass black holeOct 15 2004Observations of V404 Cyg performed with the Westerbork Synthesis Radio Telescope at four frequencies, over the interval 1.4-8.4 GHz, have provided us with the first broadband radio spectrum of a `quiescent' stellar mass black hole. The measured mean flux ... More
Neutral hydrogen absorption towards Fast Radio BurstsMay 05 2015If Fast Radio Bursts (FRBs) are truly at astronomical, in particular cosmological, distances, they represent one of the most exciting discoveries in astrophysics of the past decade. However, the distance to FRBs has, to date, been estimated purely from ... More
Maximal Beable Subalgebras of Quantum-Mechanical ObservablesMay 13 1999Given a state on an algebra of bounded quantum-mechanical observables (the self-adjoint part of a C*-algebra), we investigate those subalgebras that are maximal with respect to the property that the given state's restriction to the subalgebra is a mixture ... More
Entanglement and Open Systems in Algebraic Quantum Field TheoryJan 28 2000Entanglement has long been the subject of discussion by philosophers of quantum theory, and has recently come to play an essential role for physicists in their development of quantum information theory. In this paper we show how the formalism of algebraic ... More
Simulating Quantum Mechanics by Non-Contextual Hidden VariablesAug 09 1999May 29 2000No physical measurement can be performed with infinite precision. This leaves a loophole in the standard no-go arguments against non-contextual hidden variables. All such arguments rely on choosing special sets of quantum-mechanical observables with measurement ... More
A pliable lasso for the Cox modelJul 18 2018We introduce a pliable lasso method for estimation of interaction effects in the Cox proportional hazards model framework. The pliable lasso is a linear model that includes interactions between covariates X and a set of modifying variables Z and assumes ... More
An optimal adaptive wavelet method for First Order System Least SquaresNov 16 2017In this paper, it is shown that any well-posed 2nd order PDE can be reformulated as a well-posed first order least squares system. This system will be solved by an adaptive wavelet solver in optimal computational complexity. The applications that are ... More
Lipid Domain Order and the Algebra of MorphologyMay 09 2009Lipid membranes regulate the flow of materials and information between cells and their organelles. Further, lipid composition and morphology can play a key role in regulating a variety of biological processes. For example, viral uptake, plasma membrane ... More
Analytic models for mechanotransduction: gating a mechanosensitive channelNov 10 2003Analytic estimates for the forces and free energy generated by bilayer deformation reveal a compelling and intuitive model for MscL channel gating analogous to the nucleation of a second phase. We argue that the competition between hydrophobic mismatch ... More
How the Avidity of Polymerase Binding to the -35/-10 Promoter Sites Affects Gene ExpressionApr 03 2019Although the key promoter elements necessary to drive transcription in Escherichia coli have long been understood, we still cannot predict the behavior of arbitrary novel promoters, hampering our ability to characterize the myriad of sequenced regulatory ... More
Meet-completions and ordered domain algebrasFeb 23 2015Using the well-known equivalence between meet-completions of posets and standard closure operators we show a general method for constructing meet-completions for isotone poset expansions. With this method we find a meet-completion for ordered domain algebras ... More
Bounds for approximate discrete tomography solutionsJul 17 2012In earlier papers we have developed an algebraic theory of discrete tomography. In those papers the structure of the functions $f: A \to \{0,1\}$ and $f: A \to \mathbb{Z}$ having given line sums in certain directions have been analyzed. Here $A$ was a ... More
Higher order intersection numbers of 2-spheres in 4-manifoldsAug 07 2000Nov 17 2000This is the beginning of an obstruction theory for deciding whether a map f:S^2 --> X^4 is homotopic to a topologically flat embedding, in the presence of fundamental group and in the absence of dual spheres. The first obstruction is Wall's self-intersection ... More
(Dual) Hoops Have Unique HalvingMar 02 2012Oct 14 2013Continuous logic extends the multi-valued Lukasiewicz logic by adding a halving operator on propositions. This extension is designed to give a more satisfactory model theory for continuous structures. The semantics of these logics can be given using specialisations ... More
Stability of Galerkin discretizations of a mixed space-time variational formulation of parabolic evolution equationsFeb 17 2019We analyze Galerkin discretizations of a new well-posed mixed space-time variational formulation of parabolic PDEs. For suitable pairs of finite element trial spaces, the resulting Galerkin operators are shown to be uniformly stable. The method is compared ... More
Homotopy versus isotopy: spheres with duals in 4--manifoldsApr 28 2019David Gabai recently proved a smooth 4-dimensional ``Light Bulb Theorem'' in the absence of involutions in the fundamental group. More precisely, he showed that homotopy implies isotopy for embedded 2-spheres which have a common geometric dual. We extend ... More
Jet-dominated advective systems of all mass scalesNov 21 2006We show that the radio emission of black hole (BH) and neutron star (NS) X-ray binaries (XRBs) follows the analytical prediction of a jet model where the jet carries a constant fraction of the accretion power. The radio emission can therefore be used ... More
MSSM soft terms from supergravity with gauged R-symmetry in de Sitter vacuumJul 24 2015We work out the phenomenology of a model of supersymmetry breaking in the presence of a tiny (tunable) positive cosmological constant, proposed by the authors in arXiv:1403.1534. It utilises a single chiral multiplet with a gauged shift symmetry, that ... More
High energy emission from microquasarsOct 20 2003The microquasar phenomenon is associated with the production of jets by X-ray binaries and, as such, may be associated with the majority of such systems. In this chapter we briefly outline the associations, definite, probable, possible, and speculative, ... More
Predicting Depth, Surface Normals and Semantic Labels with a Common Multi-Scale Convolutional ArchitectureNov 18 2014Dec 17 2015In this paper we address three different computer vision tasks using a single basic architecture: depth prediction, surface normal estimation, and semantic labeling. We use a multiscale convolutional network that is able to adapt easily to each task using ... More
Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos CatalogueJul 02 2010Nov 02 2010We develop Bayesian statistical methods for discovering and assigning probabilities to non-random (e.g., physical) stellar companions. These companions are either presently bound or were previously bound. The probabilities depend on similarities in corrected ... More
A Submillimeter Survey of Gravitationally Lensed QuasarsJan 25 2002Submillimeter (and in some cases millimeter) wavelength continuum measurements are presented for a sample of 40 active galactic nuclei (probably all quasars) lensed by foreground galaxies. The object of this study is to use the lensing boost, anywhere ... More