Long-Time Behaviour and Self-Similarity in a Coagulation Equation with Input of Monomers

For a coagulation equation with Becker-Doring type interactions and time-independent monomer input we study the detailed long-time behaviour of nonnegative solutions and prove the convergence to a self-similar function.Comment: 30 pages, 5 Figures, now published in Markov Processes and Related Fields 12, 367-398, (2006

Avoided crossings in mesoscopic systems: electron propagation on a non-uniform magnetic cylinder

We consider an electron constrained to move on a surface with revolution symmetry in the presence of a constant magnetic field $B$ parallel to the surface axis. Depending on $B$ and the surface geometry the transverse part of the spectrum typically exhibits many crossings which change to avoided crossings if a weak symmetry breaking interaction is introduced. We study the effect of such perturbations on the quantum propagation. This problem admits a natural reformulation to which tools from molecular dynamics can be applied. In turn, this leads to the study of a perturbation theory for the time dependent Born-Oppenheimer approximation

Efeito da umidade do solo sobre o dano da lagarta Elasmo, Elasmopalpus lignosellus (Zeller) na cultura do milho.

O objetivo deste trabalho foi estudar o efeito da umidade do solo sobre o ataque da lagarta elasmo, Elasmopalpus lignosellus (Zeller), na cultura do milho. Avaliou-se o efeito de seis laminas de agua sobre o dano causado pela lagarta, com idade de quatro, 10 e 15 dias. Atraves de irrigacao por aspersao, aplicaram-se diariamente as laminas de agua no solo, coletando-se amostras de solo antes e apos a irrigacao, para determinar a umidade. Os resultados mostraram uma relacao quadratica entre o conteudo de umidade do solo e a porcentagem de plantas de milho atacadas pela praga. Concluiu-se que o dano causado por lagartas com ate 10 dias de idade pode ser reduzido com o manejo da umidade do solo em sistema irrigados

Properties of Very Luminous Galaxies

Recent analysis of the SSRS2 data based on cell-counts and two-point correlation function has shown that very luminous galaxies are much more strongly clustered than fainter galaxies. In fact, the amplitude of the correlation function of very luminous galaxies ($L > L^*$) asymptotically approaches that of $R \ge 0$ clusters. In this paper we investigate the properties of the most luminous galaxies, with blue absolute magnitude $M_B \le -21$. We find that: 1) the population mix is comparable to that in other ranges of absolute magnitudes; 2) only a small fraction are located in bona fide clusters; 3) the bright galaxy-cluster cross-correlation function is significantly higher on large scales than that measured for fainter galaxies; 4) the correlation length of galaxies brighter than \MB $\sim -20.0$, expressed as a function of the mean interparticle distance, appears to follow the universal dimensionless correlation function found for clusters and radio galaxies; 5) a large fraction of the bright galaxies are in interacting pairs, others show evidence for tidal distortions, while some appear to be surrounded by faint satellite galaxies. We conclude that very luminous optical galaxies differ from the normal population of galaxies both in the clustering and other respects. We speculate that this population is highly biased tracers of mass, being associated to dark halos with masses more comparable to clusters than typical loose groups.Comment: 29 pages (6 figures) + 2 tables; paper with all figures and images available at http://boas5.bo.astro.it/~cappi/papers.html; The Astronomical Journal, in pres