Jamming in a lattice model of stochastically interacting agents with a field of view

We study the collective dynamics of a lattice model of stochastically interacting agents with a weighted field of vision. We assume that agents preferentially interact with neighbours, depending on their relative location, through velocity alignments and the additional constraint of exclusion. Unlike in previous models of flocking, here the stochasticity arises intrinsically from the interactions between agents, and its strength is dependent on the local density of agents. We find that this system yields a first-order jamming transition as a consequence of these interactions, even at a very low density. Furthermore, the critical jamming density is found to strongly depend on the nature of the field of view.Comment: 5 pages, 3 figures + 3 pages supplementary materia

Manpower information

A description of the NAL nominal roll database (listing basic information about NAL employees) created using the Ingres relational database software. Using this database it is possible to provide a wide variety of reports about NAL staff, respond to a wide assortment of queries and undertake elementary statistical analysis to tabulate (and pictorially depict) the average age of NAL scientists, the future retirement pattern of NAL employees etc

Exact Persistence Exponent for One-dimensional Potts Models with Parallel Dynamics

We obtain \theta_p(q) = 2\theta_s(q) for one-dimensional q-state ferromagnetic Potts models evolving under parallel dynamics at zero temperature from an initially disordered state, where \theta_p(q) is the persistence exponent for parallel dynamics and \theta_s(q) = -{1/8}+ \frac{2}{\pi^2}[cos^{-1}{(2-q)/q\sqrt{2}}]^2 [PRL, {\bf 75}, 751, (1995)], the persistence exponent under serial dynamics. This result is a consequence of an exact, albeit non-trivial, mapping of the evolution of configurations of Potts spins under parallel dynamics to the dynamics of two decoupled reaction diffusion systems.Comment: 13 pages Latex file, 5 postscript figure

Management of Fresh water Fisheries

The book under review 'Management of Fresh Water Fisheries' by Jacques Arrignon is a very valuable compendium of knowledge on fresh water fisheries presented in three parts, such as ecological fundamentals, fish breeding and management of aquatic media. The contents of the book are a collection appropriate and authentic record of information which heavily deal with many fundamentals, topics, methodology, breeding and culture practices, management of medium which are relevant, applicable and replicable to many universal situations