Results for "Christine L. Borgman"

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Digital Data Archives as Knowledge Infrastructures: Mediating Data Sharing and ReuseFeb 08 2018Digital data archives play essential roles in knowledge infrastructures by mediating access to data within and between communities. This three-year qualitative study of DANS, a digital data archive containing more than 50 years of heterogeneous data types, ... More
Effects of Quantum Stress Tensor Fluctuations with Compact Extra DimensionsJun 16 2004The effects of compact extra dimensions upon quantum stress tensor fluctuations are discussed. It is argued that as the compactification volume decrease, these fluctuations increase in magnitude. In principle, this would have the potential to create observable ... More
Open Data, Grey Data, and Stewardship: Universities at the Privacy FrontierFeb 08 2018As universities recognize the inherent value in the data they collect and hold, they encounter unforeseen challenges in stewarding those data in ways that balance accountability, transparency, and protection of privacy, academic freedom, and intellectual ... More
From Artifacts to Aggregations: Modeling Scientific Life Cycles on the Semantic WebJun 14 2009Oct 21 2009In the process of scientific research, many information objects are generated, all of which may remain valuable indefinitely. However, artifacts such as instrument data and associated calibration information may have little value in isolation; their meaning ... More
The Durability and Fragility of Knowledge Infrastructures: Lessons Learned from AstronomyOct 31 2016Infrastructures are not inherently durable or fragile, yet all are fragile over the long term. Durability requires care and maintenance of individual components and the links between them. Astronomy is an ideal domain in which to study knowledge infrastructures, ... More
Using the Jupyter Notebook as a Tool for Open Science: An Empirical StudyApr 16 2018As scientific work becomes more computational and data intensive, research processes and results become more difficult to interpret and reproduce. In this poster, we show how the Jupyter notebook, a tool originally designed as a free version of Mathematica ... More
The Effects of Stress Tensor Fluctuations upon FocusingJul 10 2003Nov 10 2004We treat the gravitational effects of quantum stress tensor fluctuations. An operational approach is adopted in which these fluctuations produce fluctuations in the focusing of a bundle of geodesics. This can be calculated explicitly using the Raychaudhuri ... More
Selfish Routing on Dynamic FlowsJul 13 2015Selfish routing on dynamic flows over time is used to model scenarios that vary with time in which individual agents act in their best interest. In this paper we provide a survey of a particular dynamic model, the deterministic queuing model, and discuss ... More
Splitting formulae for the Kontsevich-Kuperberg-Thurston invariant of rational homology 3-spheresNov 19 2004M. Kontsevich proposed a topological construction for an invariant Z of rational homology 3-spheres using configuration space integrals. G. Kuperberg and D. Thurston proved that Z is a universal real finite type invariant for integral homology spheres ... More
Indefinite Affine Hyperspheres Admitting a Pointwise Symmetry. Part 2Oct 19 2009An affine hypersurface $M$ is said to admit a pointwise symmetry, if there exists a subgroup $G$ of ${\rm Aut}(T_p M)$ for all $p\in M$, which preserves (pointwise) the affine metric $h$, the difference tensor $K$ and the affine shape operator $S$. Here, ... More
Conditional least squares estimation in nonstationary nonlinear stochastic regression modelsJan 13 2010Let $\{Z_n\}$ be a real nonstationary stochastic process such that $E(Z_n|{\mathcaligr F}_{n-1})\stackrel{\mathrm{a.s.}}{<}\infty$ and $E(Z^2_n|{\mathcaligr F}_{n-1})\stackrel{\mathrm{a.s.}}{<}\infty$, where $\{{\mathcaligr F}_n\}$ is an increasing sequence ... More
Linear programming bounds for codes in Grassmannian spacesOct 26 2006We introduce a linear programming method to obtain bounds on the cardinality of codes in Grassmannian spaces for the chordal distance. We obtain explicit bounds, and an asymptotic bound that improves on the Hamming bound. Our approach generalizes the ... More
The rank of a hypergeometric systemJul 02 2008Feb 10 2010The holonomic rank of the A-hypergeometric system M_A(\beta) is the degree of the toric ideal I_A for generic parameters; in general, this is only a lower bound. To the semigroup ring of A we attach the ranking arrangement and use this algebraic invariant ... More
The mixed functors of the category Fquad: a first studyNov 18 2006In previous work, we defined the category of functors Fquad, associated to vector spaces over the field with two elements equipped with a nondegenerate quadratic form. In this paper, we define a special family of objects in the category Fquad, named the ... More
Characterization of the non-classical nature of conditionally prepared single photonsDec 23 2004A reliable single photon source is a prerequisite for linear optical quantum computation and for secure quantum key distribution. A criterion yielding a conclusive test of the single photon character of a given source, attainable with realistic detectors, ... More
A Survey on Latent Tree Models and ApplicationsFeb 04 2014In data analysis, latent variables play a central role because they help provide powerful insights into a wide variety of phenomena, ranging from biological to human sciences. The latent tree model, a particular type of probabilistic graphical models, ... More
Chip-based frequency combs sources for optical coherence tomographyFeb 20 2019The Optical coherence tomography (OCT) is a powerful interferometric imaging technique widely used in medical fields such as ophthalmology, cardiology and dermatology, for which footprint and cost are becoming increasingly important. Here we present a ... More
Mapping Complex Networks: Exploring Boolean Modeling of Signal Transduction PathwaysNov 03 2009Dec 14 2009In this study, we explored the utility of a descriptive and predictive bionetwork model for phospholipase C-coupled calcium signaling pathways, built with non-kinetic experimental information. Boolean models generated from these data yield oscillatory ... More
GMC Evolution in a Barred Spiral Galaxy with Star Formation and Thermal FeedbackJun 15 2016We explore the impact of star formation and thermal stellar feedback on the giant molecular cloud (GMC) population forming in a M83-type barred spiral galaxy. We compare three high-resolution simulations (1.5 pc cell size) with different star formation/feedback ... More
10 Simple Rules for the Care and Feeding of Scientific DataJan 09 2014This article offers a short guide to the steps scientists can take to ensure that their data and associated analyses continue to be of value and to be recognized. In just the past few years, hundreds of scholarly papers and reports have been written on ... More
Magneto-HydroDynamic activity and Energetic Particles - Application to Beta Alfven EigenmodesDec 14 2009The goal of magnetic fusion research is to extract the power released by fusion reactions and carried by the product of these reactions, liberated at energies of the order of a few MeV. The feasibility of fusion energy production relies on our ability ... More
Surgery formulae for finite type invariants of rational homology 3--spheresMar 12 2007We first present three graphic surgery formulae for the degree $n$ part $Z_n$ of the Kontsevich-Kuperberg-Thurston universal finite type invariant of rational homology spheres. Each of these three formulae determines an alternate sum of the form $$\sum_{I ... More
Generic representations of orthogonal groups: projective functors in the category FquadApr 04 2007In this paper, we continue the study of the category of functors Fquad, associated to F_2-vector spaces equipped with a nondegenerate quadratic form, initiated in two previous papers of the author. We define a filtration of the standard projective objects ... More
The functor category FquadJun 20 2006In this paper, we define the functor category Fquad associated to vector spaces over the field with two elements, F\_2, equipped with a quadratic form. We show the existence of a fully-faithful, exact functor \iota: \F \to Fquad, which preserves simple ... More
A Spitzer MIPS Study of 2.5-2.0 M\odot Stars in Scorpius-CentaurusJul 14 2012We have obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 {\mu}m and 70 {\mu}m observations of 215 nearby, Hipparcos B- and A-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. ... More
The Formation of Massive Cluster GalaxiesJul 08 2010We present composite 3.6 and 4.5 micron luminosity functions for cluster galaxies measured from the Spitzer Deep, Wide-Field Survey (SDWFS) for 0.3<z<2. We compare the evolution of m* for these luminosity functions to models for passively evolving stellar ... More
Large Deviations for Random TreesDec 13 2007We consider large random trees under Gibbs distributions and prove a Large Deviation Principle (LDP) for the distribution of degrees of vertices of the tree. The LDP rate function is given explicitly. An immediate consequence is a Law of Large Numbers ... More
q-Cartan matrices and combinatorial invariants of derived categories for skewed-gentle algebrasApr 27 2005Feb 24 2006Cartan matrices are of fundamental importance in representation theory. For algebras defined by quivers (i.e. directed graphs) with relations the computation of the entries of the Cartan matrix amounts to counting nonzero paths in the quivers, leading ... More
Optimality and uniqueness of the (4,10,1/6) spherical codeAug 29 2007May 14 2008Linear programming bounds provide an elegant method to prove optimality and uniqueness of an (n,N,t) spherical code. However, this method does not apply to the parameters (4,10,1/6). We use semidefinite programming bounds instead to show that the Petersen ... More
Semidefinite programming, multivariate orthogonal polynomials, and codes in spherical capsOct 27 2006Oct 18 2007We apply the semidefinite programming approach developed in arxiv:math.MG/0608426 to obtain new upper bounds for codes in spherical caps. We compute new upper bounds for the one-sided kissing number in several dimensions where we in particular get a new ... More
Thermodynamic Geodesics of a Reissner Nordström Black HoleSep 23 2016Starting from a Geometrothermodynamics metric for the space of thermodynamic equilibrium states in the mass representation, we use numerical techniques to analyse the thermodynamic geodesics of a supermassive Reissner Nordstr\"om black hole in isolation. ... More
Critical points and bifurcations of the three-dimensional Onsager model for liquid crystalsSep 08 2015We study the bifurcation diagram of the Onsager free-energy func- tional for liquid crystals with orientation parameter on the sphere in three dimensions. In particular, we concentrate on a very general class of two- body interaction potentials including ... More
Weighted locally gentle quivers and Cartan matricesNov 24 2005We study the class of weighted locally gentle quivers. This naturally extends the class of gentle quivers and gentle algebras, which have been intensively studied in the representation theory of finite-dimensional algebras, to a wider class of potentially ... More
New upper bounds for kissing numbers from semidefinite programmingAug 16 2006Oct 03 2007Recently A. Schrijver derived new upper bounds for binary codes using semidefinite programming. In this paper we adapt this approach to codes on the unit sphere and we compute new upper bounds for the kissing number in several dimensions. In particular ... More
Compactness properties for modulation spacesApr 03 2018We prove that if $\omega _1$ and $\omega _2$ are moderate weights and $\mascB$ is a suitable (quasi-)Banach function space, then a necessary and sufficient condition for the embedding $i\, :\, M (\omega _1,\mascB )\to M (\omega _2,\mascB )$ between two ... More
Characterizing entanglement in pulsed parametric downconversion using chronocyclic Wigner functionsFeb 27 2013Pulsed parametric downconversion (PDC) processes generate photon pairs with a rich spectral-temporal structure, which offer an attractive potential for quantum information and communication applications. In this paper, we investigate the four-dimensional ... More
Non-negatively curved 6-manifolds with almost maximal symmetry rankDec 06 2016We classify closed, simply-connected, non-negatively curved 6-manifolds of almost maximal symmetry rank up to equivariant diffeomorphism.
Distortions of the HelicoidMay 30 2008Colding and Minicozzi have shown that an embedded minimal disk $0\in\Sigma\subset B_R$ in $\Real^3$ with large curvature at 0 looks like a helicoid on the scale of $R$. Near 0, this can be sharpened: on the scale of $|A|^{-1}(0)$, $\Sigma$ is close, in ... More
Non-negatively curved 6-manifolds with almost maximal symmetry rankDec 06 2016Nov 15 2017We classify closed, simply-connected, non-negatively curved 6-manifolds of almost maximal symmetry rank up to equivariant diffeomorphism.
Non-negative curvature and torus actionsJun 29 2015Nov 15 2017Let $\mathcal{M}_{0}^n$ be the class of closed, simply-connected, non-negatively curved Riemannian manifolds admitting an isometric, effective, isotropy-maximal torus action. We prove that if $M\in \mathcal{M}_{0}^n$, then $M$ is equivariantly diffeomorphic ... More
Kiloparsec-scale Variations in the Star Formation Efficiency of Dense Gas: the Antennae Galaxies (NGC 4038/39)Feb 07 2019We study the relationship between dense gas and star formation in the Antennae galaxies by comparing ALMA observations of dense gas tracers (HCN, HCO$^+$, and HNC $\mathrm{J}=1-0$) to the total infrared luminosity ($\mathrm{L_{TIR}}$) calculated using ... More
Molecular Gas in Candidate Double Barred Galaxies I. The Diverse Morphology and Dynamics of NGC 2273 and NGC 5728Apr 24 2002Double bars have been proposed as a means of transporting molecular gas past inner Lindblad resonances into the nuclear regions, where it can fuel active or starburst nuclei. Thus far, the existence of double bars has been determined predominantly through ... More
Stability of the vanishing of the $\overline\partial_b$-cohomology under small horizontal perturbations of the CR structure in compact abstract q-concave CR manifoldsOct 30 2008We consider perturbations of CR structures which preserve the complex tangent bundle. For a compact generic CR manifold its concavity properties and hence the finiteness of some $\overline\partial_b$-cohomology groups are also preserved by such perturbations ... More
Poincaré lemma and global homotopy formulas with sharp anisotropic Hölder estimates in q-concave CR manifoldsOct 29 2008We prove sharp anisotropic H\"older estimates for the local solutions of the tangential Cauchy-Riemann equation in q-concave CR manifolds and we derive the same kind of estimates for global solutions when the manifold is compact.
On p-parts of Brauer character degrees and p-regular conjugacy class sizesApr 23 2018Let $G$ be a finite group, $p$ a prime, and $IBr_p(G)$ the set of irreducible $p$-Brauer characters of $G$. Let $\bar e_p(G)$ be the largest integer such that $p^{\bar e_p(G)}$ divides $\chi(1)$ for some $\chi \in IBr_p(G)$. We show that $|G:O_p(G)|_p ... More
$D$-modules arithmétiques, distributions et localisationJan 27 2014Jun 26 2017Let $p$ be a prime number, $V$ a discrete valuation ring of unequal caracteristics $(0,p)$, $G$ a smooth affine algebraic group over $Spec \,V$. Using partial divided powers techniques of Berthelot, we construct arithmetic distribution algebras, with ... More
Modified Gravity and the CMBSep 27 2011Dec 09 2011We consider the effect of modified gravity on the peak structure of the Cosmic Microwave Background (CMB) spectrum. We focus on simple models of modified gravity mediated by a massive scalar field coupled to both baryons and cold dark matter. This captures ... More
SupersymmetronSep 02 2011Dec 09 2011We consider a supersymmetric model of dark energy coupled to cold dark matter: the supersymmetron. In the absence of cold dark matter, the supersymmetron converges to a supersymmetric minimum with a vanishing cosmological constant. When cold dark matter ... More
Efficient Multi-Objective Optimization through Population-based Parallel Surrogate SearchMar 06 2019Multi-Objective Optimization (MOO) is very difficult for expensive functions because most current MOO methods rely on a large number of function evaluations to get an accurate solution. We address this problem with surrogate approximation and parallel ... More
On (almost) extreme components in Kronecker products of characters of the symmetric groupsMay 16 2011Apr 12 2013Using a recursion formula due to Dvir, we obtain information on maximal and almost maximal components in Kronecker products of characters of the symmetric groups. This is applied to confirm a conjecture made by Bessenrodt and Kleshchev in 1999, which ... More
Large Deviations for Random Trees and the Branching of RNA Secondary StructuresMar 27 2008We give a Large Deviation Principle (LDP) with explicit rate function for the distribution of vertex degrees in plane trees, a combinatorial model of RNA secondary structures. We calculate the typical degree distributions based on nearest neighbor free ... More
Smith Normal Form of a Multivariate Matrix Associated with PartitionsNov 24 2013Apr 18 2014Consideration of a question of E. R. Berlekamp led Carlitz, Roselle, and Scoville to give a combinatorial interpretation of the entries of certain matrices of determinant~1 in terms of lattice paths. Here we generalize this result by refining the matrix ... More
An Inhomogeneous Space-Time Patching Model Based on a Nonlocal and Nonlinear Schrodinger EquationMay 04 2016We consider an integrable, nonlocal and nonlinear, Schr\"odinger equation (NNSE) as a model for building space-time patchings in inhomogeneous loop quantum cosmology (LQC). We briefly review exact solutions of the NNSE, specially those obtained through ... More
An Approach to Loop Quantum Cosmology Through Integrable Discrete Heisenberg Spin ChainsSep 17 2012Nov 16 2012The quantum evolution equation of Loop Quantum Cosmology (LQC) -- the quantum Hamiltonian constraint -- is a difference equation. We relate the LQC constraint equation in vacuum Bianchi I separable (locally rotationally symmetric) models with an integrable ... More
Neutrino Mixing and the Frobenius Group T13Jun 01 2011Jul 25 2011We show that the Frobenius group $T_{13} = Z_{13} \rtimes Z_3$ is a suitable family symmetry group to study neutrino oscillations. Our approach is to catalog all possibilities within an effective field theory approach, assuming only SU(2)xU(1) supplemented ... More
Five guidelines for the evaluation of site-specific medium range probabilistic temperature forecastsOct 04 2003Probabilistic temperature forecasts are potentially useful to the energy and weather derivatives industries. However, at present, they are little used. There are a number of reasons for this, but we believe this is in part due to inadequacies in the methodologies ... More
Observed Cosmological Reexpansion in Minimal QFT with Bose and Fermi FieldsJul 14 2014In this work we aim at explaining the re-acceleration of the expansion of the universe, or equivalently, the hierarchy problem, with the help of a simple field-theoretical model. In particular, we want to account for the notorious discrepancy between ... More
Un théorème de Beilinson-Bernstein pour les D-modules arithmétiquesApr 30 2007May 25 2007One proves a Beilinson-Bernstein theorem in the context of arithmetic D-modules introduced by Berthelot, for flag varieties. This generalizes in the arithmetic context previous results of Brylinski-Kashiwara and Beilinson-Bernstein in the complex case. ... More
$(\varphi,Γ)$-modules associés aux courbes hyperelliptiques lissesJun 07 2013Jan 02 2014In 2003, Kedlaya gave an algorithm to compute the zeta function associated to a hyperelliptic curve over a finite field, by computing the rigid cohomology of the curve. Edixhoven remarked that it is actually possible to compute the crystalline cohomology ... More
Sur l'homologie des groupes orthogonaux et symplectiques à coefficients tordusAug 29 2008Oct 19 2009We compute the stable homology of orthogonal and symplectic groups over a finite field k with coefficients coming from an usual endofunctor F of k-vector spaces (exterior, symmetric, divided powers...), that is, for all natural integer i, we compute the ... More
Detecting highly cyclic structure with complex eigenpairsAug 24 2016Many large, real-world complex networks have rich community structure that a network scientist seeks to understand. These communities may overlap or have intricate internal structure. Extracting communities with particular topological structure, even ... More
Dynamic nuclear polarization in a magnetic resonance force microscope experimentJan 27 2016Feb 18 2016We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves ... More
The Wyoming Survey for H-alpha. I. Initial Results at z ~ 0.16 and 0.24Feb 05 2008The Wyoming Survey for H-alpha, or WySH, is a large-area, ground-based, narrowband imaging survey for H-alpha-emitting galaxies over the latter half of the age of the Universe. The survey spans several square degrees in a set of fields of low Galactic ... More
Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field linesMar 18 2011The issue of magnetic confinement in magnetic fusion devices is addressed within a purely magnetic approach. Using some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is shown in a unified way. Away from resonances, ... More
Solitons of discrete curve shorteningAug 28 2015Jun 20 2016For a polygon in Euclidean space we consider a transformation T which is obtained by applying the midpoints polygon construction twice and using an index shift. For a closed polygon this is a curve shortening process. A polygon is called (affine) soliton ... More
The quadratic assignment problem: the linearization of Xia and Yuan is weaker than the linearization of Adams and Johnson and a family of cuts to narrow the gapOct 06 2017Jun 29 2018The quadratic assignment problem is a well-known optimization problem with numerous applications. A common strategy to solve it is to use one of its linearizations and then apply the toolbox of mixed integer linear programming methods. One measure of ... More
Multiplicity free Schur, skew Schur, and quasisymmetric Schur functionsMay 21 2011Mar 02 2012In this paper we classify all Schur functions and skew Schur functions that are multiplicity free when expanded in the basis of fundamental quasisymmetric functions, termed F-multiplicity free. Combinatorially, this is equivalent to classifying all skew ... More
Logarithmically spiraling helicoidsApr 28 2014Apr 29 2014We construct helicoid-like embedded minimal disks with axes along self-similar curves modeled on logarithmic spirals. The surfaces have a self-similarity inherited from the curves and the nature of the construction. Moreover, inside of a "logarithmic ... More
Recurrent Surface HomeomorphismsMar 20 2003Mar 02 2009An orientation-preserving recurrent homeomorphism of the two-sphere which is not the identity is shown to admit exactly two fixed points. A recurrent homeomorphism of a compact surface with negative Euler characteristic is periodic.
Deconvolving RNA Base Pairing SignalsJan 09 2018The structure of an RNA sequence encodes information about its biological function. A sequence is typically predicted to fold to a single minimum free energy conformation. But, an increasing number of RNA molecules are now known to fold into multiple ... More
Filling area conjecture, optimal systolic inequalities, and the fiber class in abelian coversDec 01 2004Sep 23 2005We investigate the filling area conjecture, optimal systolic inequalities, and the related problem of the nonvanishing of certain linking numbers in 3-manifolds.
Superconducting Optoelectronic Neurons III: Synaptic PlasticityMay 04 2018Jul 03 2018As a means of dynamically reconfiguring the synaptic weight of a superconducting optoelectronic loop neuron, a superconducting flux storage loop is inductively coupled to the synaptic current bias of the neuron. A standard flux memory cell is used to ... More
Stationary analysis of the shortest queue problemApr 21 2017Dec 12 2017A simple analytical solution is proposed for the stationary loss system of two parallel queues with finite capacity $K$, in which new customers join the shortest queue, or one of the two with equal probability if their lengths are equal. The arrival process ... More
A versatile and accurate approximation for LRU cache performanceFeb 17 2012In a 2002 paper, Che and co-authors proposed a simple approach for estimating the hit rates of a cache operating the least recently used (LRU) replacement policy. The approximation proves remarkably accurate and is applicable to quite general distributions ... More
Generalized frieze pattern determinants and higher angulations of polygonsMay 06 2013Jun 16 2014Frieze patterns (in the sense of Conway and Coxeter) are in close connection to triangulations of polygons. Broline, Crowe and Isaacs have assigned a symmetric matrix to each polygon triangulation and computed the determinant. In this paper we consider ... More
Nuclear Masses in AstrophysicsDec 09 2008Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry ... More
Pseudocodewords of Tanner graphsApr 05 2005Aug 18 2007This papers presents a detailed analysis of pseudocodewords of Tanner graphs. Pseudocodewords arising on the iterative decoder's computation tree are distinguished from pseudocodewords arising on finite degree lifts. Lower bounds on the minimum pseudocodeword ... More
LoCuSS: Scaling relations between galaxy cluster mass, gas, and stellar contentJan 31 2019We present a simultaneous analysis of galaxy cluster scaling relations between weak-lensing mass and multiple cluster observables, across a wide range of wavelengths, that probe both gas and stellar content. Our new hierarchical Bayesian model simultaneously ... More
Adjusting for Unmeasured Spatial Confounding with Distance Adjusted Propensity Score MatchingOct 24 2016Propensity score matching is a common tool for adjusting for observed confounding in observational studies, but is known to have limitations in the presence of unmeasured confounding. In many settings, researchers are confronted with spatially-indexed ... More
Pulsar Constraints on Screened Modified GravityJan 23 2013Jul 25 2014We calculate the rate of energy loss from compact astrophysical objects due to a scalar field in screened modified gravity models of the chameleon, dilaton and symmetron types. The cosmological evolution of the field results in a time-variation of the ... More
SUPER-ScreeningDec 18 2012We present a framework for embedding scalar-tensor models of screened modifed gravity such as chameleons, symmetrons and environmental dilatons into global supersymmetry. This achieved by secluding the dark sector from both the observable and supersymmetry ... More
Signatures of Modified Gravity on the 21-cm Power Spectrum at ReionisationJul 05 2012Jul 12 2012Scalar modifications of gravity have an impact on the growth of structure. Baryon and Cold Dark Matter (CDM) perturbations grow anomalously for scales within the Compton wavelength of the scalar field. In the late time Universe when reionisation occurs, ... More
Torus equivariant D-modules and hypergeometric systemsAug 27 2013Jun 12 2018We formalize, at the level of D-modules, the notion that A-hypergeometric systems are equivariant versions of the classical hypergeometric equations. For this purpose, we construct a functor on a suitable category of torus equivariant D-modules and show ... More
Primitive Collections and Toric VarietiesAug 13 2008Sep 03 2008This paper studies Batyrev's notion of primitive collection. We use primitive collections to characterize the nef cone of a quasi-projective toric variety whose fan has convex support, a result stated without proof by Batyrev in the smooth projective ... More
All $SL_2$-tilings come from infinite triangulationsMar 30 2016May 24 2017An $SL_2$-tiling is a bi-infinite matrix of positive integers such that each adjacent 2 by 2 submatrix has determinant 1. Such tilings are infinite analogues of Conway-Coxeter friezes, and they have strong links to cluster algebras, combinatorics, mathematical ... More
Disformally Coupled Scalar Fields and Inspiralling TrajectoriesMar 09 2019We show how a nearly massless scalar field conformally and disformally coupled to matter can affect the dynamics of two bodies in their inspiralling phase before merging. We discuss both the conservative dynamics, e.g. how the energy of the bound system ... More
Convergence Stability for Ricci FlowMay 01 2018The principle of convergence stability for geometric flows is the combination of the continuous dependence of the flow on initial conditions, with the stability of fixed points. It implies that if the flow from an initial state $g_0$ exists for all time ... More
Crosscap numbers and the Jones polynomialAug 19 2014Sep 22 2015We give sharp two-sided linear bounds of the crosscap number (non-orientable genus) of alternating links in terms of their Jones polynomial. Our estimates are often exact and we use them to calculate the crosscap numbers for several infinite families ... More
Normal and Jones surfaces of knotsFeb 21 2017Mar 23 2018We describe a normal surface algorithm that decides whether a knot, with known degree of the colored Jones polynomial, satisfies the Strong Slope Conjecture. We also discuss possible simplifications of our algorithm and state related open questions. We ... More
Perturbation Biology: inferring signaling networks in cellular systemsAug 23 2013We present a new experimental-computational technology of inferring network models that predict the response of cells to perturbations and that may be useful in the design of combinatorial therapy against cancer. The experiments are systematic series ... More
Fine-grained Material Associated with a Large Sulfide returned from Comet 81P/Wild 2Jun 29 2018In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine-grained material (FGM) in contact with a large sulfide particle. The FGM was partially located ... More
On the edge capacitated Steiner tree problemJul 24 2016Given a graph G = (V,E) with a root r in V, positive capacities {c(e)|e in E}, and non-negative lengths {l(e)|e in E}, the minimum-length (rooted) edge capacitated Steiner tree problem is to find a tree in G of minimum total length, rooted at r, spanning ... More
Dark Energy and Doubly Coupled BigravityJun 17 2016Nov 04 2016We analyse the late time cosmology and the gravitational properties of doubly coupled bigravity in the constrained vielbein formalism (equivalent to the metric formalism) when the mass of the massive graviton is of the order of the present Hubble rate. ... More
Geometric approaches to the thermodynamics of black holesMar 31 2016May 30 2016In this summary, we present the main topics of the talks presented in the parallel session "Black holes - 5" of the 14th Marcel Grossmann Meeting held in Rome, Italy in July 2015. We first present a short review of the main approaches used to understand ... More
Formation of Topological Defects in a Second Order Phase TransitionMar 11 1994The classical evolution equations of the Abelian Higgs model are studied at temperatures below the Ginsburg temperature of a phase transition which is assumed to be second order. It is shown that the initial thermal fluctuations provide a domain structure ... More
Cohomology rings of certain seven dimensional manifoldsOct 11 2008Dec 08 2008We calculate the cohomology rings of a collection of seven dimensional manifolds supporting an S^3 x S^3-action with one dimensional orbit space. These manifolds are of interest to differential geometers studying non-negative and positive sectional curvature. ... More
Investigating the importance of edge-structure in the loss of H/H2 of PAH cations: the case of dibenzopyrene isomersNov 08 2017We present a detailed study of the main dehydrogenation processes of two dibenzopyrene cation (C24H14+) isomers, namely dibenzo(a,e)pyrene (AE+) and dibenzo(a,l)pyrene (AL+). First, action spectroscopy under VUV photons was performed using synchrotron ... More
Polynomial functors from Algebras over a set-operad and non-linear Mackey functorsSep 07 2012Sep 11 2012In this paper, we give a description of polynomial functors from (finitely generated free) groups to abelian groups in terms of non-linear Mackey functors generalizing those given in a paper of Baues-Dreckmann-Franjou-Pirashvili published in 2001. This ... More
Revisiting Kneser's Theorem for Field ExtensionsOct 05 2015Feb 24 2017A Theorem of Hou, Leung and Xiang generalised Kneser's addition Theorem to field extensions. This theorem was known to be valid only in separable extensions, and it was a conjecture of Hou that it should be valid for all extensions. We give an alternative ... More
Prediction and Sampling with Local Graph Transforms for Quasi-Lossless Light Field CompressionMar 08 2019Graph-based transforms have been shown to be powerful tools in terms of image energy compaction. However, when the support increases to best capture signal dependencies, the computation of the basis functions becomes rapidly untractable. This problem ... More