Terrissa gironina trobada a la Casa de Cultura

Descripció de les peces de terrissa que el museu Arqueològic de Catalunya–Girona guarda de l’antiga Casa de la Misericòrdia i antic Hospici, actualment Casa de Cultura, de Girona. Inclou un breu resum sobre l’edifici

[Ressenya del llibre Ullastret: guía de las excavaciones y su museo, d'Aurora Martín Ortega]

Ressenya del llibre Ullastret: guía de las excavaciones y su museo. Ullastret és un dels pocs jaciments que reuneixen les condicions òptimes per a ésser visitat. Però, per tal que sigui ben profitosa, calia oferir al visitant una guia que expliqués les principals característiques del lloc i el llibre de l’Aurora Martín ho fa

Fronts from complex two-dimensional dispersal kernels: theory and application to Reid's paradox

Bimodal dispersal probability distributions with characteristic distances differing by several orders of magnitude have been derived and favorably compared to observations by Nathan [Nature (London) 418, 409 (2002)]. For such bimodal kernels, we show that two-dimensional molecular dynamics computer simulations are unable to yield accurate front speeds. Analytically, the usual continuous-space random walks (CSRWs) are applied to two dimensions. We also introduce discrete-space random walks and use them to check the CSRW results (because of the inefficiency of the numerical simulations). The physical results reported are shown to predict front speeds high enough to possibly explain Reid's paradox of rapid tree migration. We also show that, for a time-ordered evolution equation, fronts are always slower in two dimensions than in one dimension and that this difference is important both for unimodal and for bimodal kernels