Biomedical subjects

H Larralde

Publications and source records attributed to H Larralde.

15 recordsLinked to original sources

PubMed2001

Simple model of a random walk with arbitrarily long memory.

We present a generalization of the persistent random-walk model in which the step at time n depends on the state of the step at time n-T, for arbitrary T. This gives rise to arbitrarily long memory effects, yet by an appropriate transformation the model is tractable by essentially the same techniques applicable to the usual persistent random-walk problem. We apply our results to the specific case of delayed "step" persistence, and analyze its asymptotic statistical properties.

Journal Article↗

PubMed2000

Dynamical weight functions for a planar crack

The stress intensity factors are evaluated for a moving planar crack for loadings which vary arbitrarily in time and three dimensions of space. We exploit the adjoint elasticity equation obeyed by the corresponding weight functions, and a new and more universal Wiener-Hopf factorization of the Rayleigh function, this being the central difficulty in such calculations. For the mode II weight function we give further asymptotic results crucial to a subsequent calculation of crack stability with respect to out-of-plane perturbations.

Journal Article↗

PubMed2000

Statistical characterization of random electrostatic potentials

In this work we study statistical properties of random electrostatic potentials generated by one dimensional lattices with random charges. We show that the resulting random potentials are correlated Gaussian processes, satisfying the Lindeberg version of the central limit theorem, if certain restrictions are imposed on the individual potentials generated by the particles on the lattice. Since most of the point-particle electrostatic potentials occurring in nature satisfy the Lindeberg condition, the correlation properties of the random potentials are not arbitrary and must comply with the central limit theorem. Based on this theorem we can obtain explicit expressions for these correlations. We thus are able to give a characterization of a broad class of potentials yielding feasible physical scenarios. We illustrate some consequences of our findings by considering dynamical properties of a test particle interacting with the lattice. We show how the long range correlations generate statistical features in these properties, which are best exhibited when considering different length scales.

Journal Article↗

PubMed1996