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

Realistic Chemotherapeutic policies for Tuberculosis in India

A series of controlled studies carried out at the Tuberculosis Chemotherapy Centre have revealed that ambulatory chemotherapy for tuberculosis based on a well-organized clinic service for a year, is virtually as effective as sanatorium treatment for the same period, not only in the immediate therapeutic response in terms of overall radiographic improvement, cavity closure and sputum conversion (Tuberculosis Chemotherapy Centre, Madras, 1959) but also in the likelihood of relapse in a subsequent 4-year period of follow-up (Dawson et al, 1966). Further, principally owing to the rapid sputum conversion of patients receiving effective chemotherapy there was no increased risk of contracting the disease to close family contacts of the patients treated at home, the main risk to them being before treatment had begun (Andrews et al, 1960; Kamat et al, 1966). These studies also clearly showed that the traditionally held virtues of sanatorium treatment namely, prolonged bed-rest, good diet, good airy accommodation, nursing and isolation were remarkably unimportant provided adequate chemotherapy was administered. There have been 5 other controlled trials based on random allocation . reported in the world medical literature which compared either sanatorium treatment with clinic treatment (Tyrell, 1956 ; Bell, 1960) or rest with ambulation (Kay, 1957 ; Tuberculosis Society of Scotland, 1960; Wier et al, 1957 ; Wynn-Williams and Shaw, 1960) and not one demonstrated any advantage either of sanatorium treatment over clinic treatment or of rest over ambulation. Because of these findings and because of the gross shortage of hospital beds for tuberculosis, ambulatory chemotherapy for the major or the entire period of treatment has become the accepted practice in the tuberculosis control programmes in India as well as in many other developing countries of the world