1,041 research outputs found

    Gaussian limits for multidimensional random sequential packing at saturation (extended version)

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    Consider the random sequential packing model with infinite input and in any dimension. When the input consists of non-zero volume convex solids we show that the total number of solids accepted over cubes of volume λ\lambda is asymptotically normal as λ\lambda \to \infty. We provide a rate of approximation to the normal and show that the finite dimensional distributions of the packing measures converge to those of a mean zero generalized Gaussian field. The method of proof involves showing that the collection of accepted solids satisfies the weak spatial dependence condition known as stabilization.Comment: 31 page

    Magnetism, FeS colloids, and Origins of Life

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    A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via physicalphysical interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed Krishnaswami Alladi, Springer 201

    Random parking, Euclidean functionals, and rubber elasticity

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    We study subadditive functions of the random parking model previously analyzed by the second author. In particular, we consider local functions SS of subsets of Rd\mathbb{R}^d and of point sets that are (almost) subadditive in their first variable. Denoting by ξ\xi the random parking measure in Rd\mathbb{R}^d, and by ξR\xi^R the random parking measure in the cube QR=(R,R)dQ_R=(-R,R)^d, we show, under some natural assumptions on SS, that there exists a constant SˉR\bar{S}\in \mathbb{R} such that % limR+S(QR,ξ)QR=limR+S(QR,ξR)QR=Sˉ \lim_{R\to +\infty} \frac{S(Q_R,\xi)}{|Q_R|}\,=\,\lim_{R\to +\infty}\frac{S(Q_R,\xi^R)}{|Q_R|}\,=\,\bar{S} % almost surely. If ζS(QR,ζ)\zeta \mapsto S(Q_R,\zeta) is the counting measure of ζ\zeta in QRQ_R, then we retrieve the result by the second author on the existence of the jamming limit. The present work generalizes this result to a wide class of (almost) subadditive functions. In particular, classical Euclidean optimization problems as well as the discrete model for rubber previously studied by Alicandro, Cicalese, and the first author enter this class of functions. In the case of rubber elasticity, this yields an approximation result for the continuous energy density associated with the discrete model at the thermodynamic limit, as well as a generalization to stochastic networks generated on bounded sets.Comment: 28 page

    Weighted second-order Poincaré inequalities: Application to RSA models

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    Consider an ergodic stationary random field A on the ambient space R d. In a recent work we introduced the notion of weighted (first-order) functional inequalities , which extend standard functional inequalities like spectral gap, covariance, and logarithmic Sobolev inequalities, while still ensuring strong concentration properties. We also developed a constructive approach to these weighted inequalities, proving their validity for prototypical examples like Gaussian fields with arbitrary covariance function , Voronoi and Delaunay tessellations of Poisson point sets, and random sequential adsorption (RSA) models, which do not satisfy standard functional inequalities. In the present contribution, we turn to second-order Poincaré inequalities à la Chatterjee: while first-order inequalities quantify the distance to constants for nonlinear functions X(A) in terms of their local dependence on the random field A, second-order inequalities quantify their distance to normality. For the above-mentioned examples, we prove the validity of suitable weighted second-order Poincaré inequalities. Applied to RSA models, these functional inequalities allow us to complete and improve previous results by Schreiber, Penrose, and Yukich on the jamming limit, and to propose and fully analyze a more efficient algorithm to approximate the latter

    The 5th Conference of PhD Students in Computer Science

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    Quantification of uncertainty in coarse-scale relative permeability for reservoir production forecast

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