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

Finfish resources in the north eastern region in the Indian EEZ

Bottom trawling conducted in 53 stations lat. 16°00'N -20°30'N; long. 81°30'E - 87°15'E revealed a production range of 3 - 15000 kg/haul with a mean of 581 kg/haul; the average catch in the region was 567.3 kg/hr. The dominant finfish in the surveyed area were Indian drift fish (36.4%), carangids (22.5%), catfishes (7.1%), bull's eye (6.9%), goat fishes (3.9%), nemipterids (3.3%) etc. The bathymetric zones above 200 m and 51-100 m were found to be highly productive with average catch rate of 1615 and 830 kg/hr respectively. In the surveyed region the highest production rate was at lat. 19°N (1384 kg/hr)

Inactivators of Isoniazid, Based on The Ratio of The Urinary Excretion of Acetylisoniazid To Isoniazid

Following an intramuscular injection of isoniazid 3 mg/kg body-weight, the urinary excretion of isoniazid and acetylisoniazid during the periods 0-1, 1-2, 2-3 and 3-4 h was determined for 124 patients with pulmonary tuberculosis. On the same occasion, the serum isoniazid concentration at 4½ h was determined by microbiologic assay. The ratios of acetylisoniazid to isoniazid in the urine collections at 2, 3 and 4 h. were bimodally distributed. Rules were derived from these. ratios for classifying subjects as slow or rapid inactivators of isoniazid. There was 100% agreement between the classification based on each of these ratios and that based on the serum isoniazid concentration at 4½ h

Persistence at the onset of spatiotemporal intermittency in coupled map lattices

We study persistence in coupled circle map lattices at the onset of spatiotemporal intermittency, an onset which marks a continuous transition, in the universality class of directed percolation, to a unique absorbing state. We obtain a local persistence exponent of theta_l = 1.49 +- 0.02 at this transition, a value which closely matches values for theta_l obtained in stochastic models of directed percolation. This result constitutes suggestive evidence for the universality of persistence exponents at the directed percolation transition. Given that many experimental systems are modelled accurately by coupled map lattices, experimental measurements of this persistence exponent may be feasible.Comment: 7 pages, Latex, 6 Postscript figures, Europhysics Letters (to appear

On the mathematical modeling of wound healing angiogenesis in skin as a reaction-transport process

Over the last 30 years, numerous research groups have attempted to provide mathematical descriptions of the skin wound healing process. The development of theoretical models of the interlinked processes that underlie the healing mechanism has yielded considerable insight into aspects of this critical phenomenon that remain difficult to investigate empirically. In particular, the mathematical modeling of angiogenesis, i.e., capillary sprout growth, has offered new paradigms for the understanding of this highly complex and crucial step in the healing pathway. With the recent advances in imaging and cell tracking, the time is now ripe for an appraisal of the utility and importance of mathematical modeling in wound healing angiogenesis research. The purpose of this review is to pedagogically elucidate the conceptual principles that have underpinned the development of mathematical descriptions of wound healing angiogenesis, specifically those that have utilized a continuum reaction-transport framework, and highlight the contribution that such models have made toward the advancement of research in this field. We aim to draw attention to the common assumptions made when developing models of this nature, thereby bringing into focus the advantages and limitations of this approach. A deeper integration of mathematical modeling techniques into the practice of wound healing angiogenesis research promises new perspectives for advancing our knowledge in this area. To this end we detail several open problems related to the understanding of wound healing angiogenesis, and outline how these issues could be addressed through closer cross-disciplinary collaboration

Triangle percolation in mean field random graphs -- with PDE

We apply a PDE-based method to deduce the critical time and the size of the giant component of the ``triangle percolation'' on the Erd\H{o}s-R\'enyi random graph process investigated by Palla, Der\'enyi and VicsekComment: Summary of the changes made: We have changed a remark about k-clique percolation in the first paragraph. Two new paragraphs are inserted after equation (4.4) with two applications of the equation. We have changed the names of some variables in our formula

Nonequilibrium steady states in a vibrated-rod monolayer: tetratic, nematic and smectic correlations

We study experimentally the nonequilibrium phase behaviour of a horizontal monolayer of macroscopic rods. The motion of the rods in two dimensions is driven by vibrations in the vertical direction. Aside from the control variables of packing fraction and aspect ratio that are typically explored in molecular liquid crystalline systems, due to the macroscopic size of the particles we are also able to investigate the effect of the precise shape of the particle on the steady states of this driven system. We find that the shape plays an important role in determining the nature of the orientational ordering at high packing fraction. Cylindrical particles show substantial tetratic correlations over a range of aspect ratios where spherocylinders have previously been shown by Bates et al (JCP 112, 10034 (2000)) to undergo transitions between isotropic and nematic phases. Particles that are thinner at the ends (rolling pins or bails) show nematic ordering over the same range of aspect ratios, with a well-established nematic phase at large aspect ratio and a defect-ridden nematic state with large-scale swirling motion at small aspect ratios. Finally, long-grain, basmati rice, whose geometry is intermediate between the two shapes above, shows phases with strong indications of smectic order.Comment: 18 pages and 13 eps figures, references adde

Pseudomoduli Dark Matter

We point out that pseudomoduli -- tree-level flat directions that often accompany dynamical supersymmetry breaking -- can be natural candidates for TeV-scale dark matter in models of gauge mediation. The idea is general and can be applied to different dark matter scenarios, including (but not limited to) those of potential relevance to recent cosmic ray anomalies. We describe the requirements for a viable model of pseudomoduli dark matter, and we analyze two example models to illustrate the general mechanism -- one where the pseudomoduli carry Higgsino-like quantum numbers, and another where they are SM singlets but are charged under a hidden-sector $U(1)'$ gauge group.Comment: 20 pages, refs adde

A double-blind study to determine the maximum tolerated dose of ethionamide, when administered twice-weekly to patients with pulmonary tuberculosis

ATI earlier report from this Centre (Tuber-culosis Chemotherapy Centre, Madras, 1964) showed that a fully supervised twice-weekly regimen of streptomycin plus high-dosage isoniazid was highly effective in the treatment of patients with newly-diagnosed bacteriologi-cally confirmed pulmonary tuberculosis. How-ever, this regimen involves intramuscular injections of streptomycin and may not always be easy to organize, especially in rural areas and in developing countries with limited resources. For this reason, it was decided to investigate the possibility of replacing strepto-mycin in the twice-weekly regimen by two oral drugs, namely ethionamide and PAS. Ethiona-mide was chosen since, apart from isoniazid and streptomycin, it was the most potent drug available at the time, and PAS was included with a view to enhance the efficacy of the regimen. Finally, it was decided that the patients should be given an intensive phase of daily treatment with streptomycin, PAS and isoniazid for two weeks. Experiments in the guinea-pig had shown that the size of the individual dose of a drug needed to be increased as the interval between successive doses was increased (Dickinson & Mitchison, 1966). As PAS is bulky and the dosage of isoniazid in the twice-weekly regimen was already high, namely 15 mg./kg. body-weight, it was decided to explore the possibility of increasing the dosage of ethionamide to a level higher than that usually employed (0.5— 1.0 g.) in daily regimens. An investigation was therefore undertaken to determine the maximum tolerated dose of ethionamide. when administered twice-weekly together with isonia-zid plus PAS. Since the assessment of ethio-namide intolerance is largely subjective, the study was conducted ‘double-blind’ with respect to the dosage of ethionamide

Long term follow up of HIV-infected patients with tuberculosis treated with 6-month intermittent short course chemotherapy

Background . Tuberculosis occurs in 60%–70% of HIVpositive persons in India. The outcome of HIV-positive patients treated with 6-month intermittent short course antituberculosis regimens in India is not well described. Methods . This was a prospective observational feasibility study of 71 patients with HIV and tuberculosis who were treated with category I regimen of the Revised National Tuberculosis Control Programme (ethambutol, isoniazid, rifampicin and pyrazinamide thrice weekly for the initial 2 months followed by rifampicin and isoniazid thrice weekly for the next 4 months). Sputum was examined by smear and culture for Mycobacterium tuberculosis every month up to 24 months. Chest X-ray, CD4 cell count and viral load were done prior to and at the end of treatment. None of the patients received antiretroviral therapy. Results . We present here the treatment response of patients with sputum culture-positive pulmonary tuberculosis to category I regimen. By efficacy analysis, among 43 patients treated with category I regimen, sputum smear conversion was observed in 79% and culture conversion in 82% at the second month. A favourable response was seen in 72% of patients. The mean (SD) CD4% fell from 12.6 (5.9) to 8.9 (4.9) (p<0.001) with no significant change in mean (SD) CD4 cell count (169 [126] to 174 [158]; ns) at the end of treatment. Viral load change from 1.8x105 at baseline to 1.3x105 at the end of treatment was not statistically significant. Thirty-one patients, who completed the full course of treatment, were declared cured and were followed up for 24 months. Twelve had recurrent tuberculosis (39%); 16 of 43 (37%) patients had died by the end of 24 months, twothirds due to causes other than tuberculosis. Conclusion . Though the early bacteriological response to intermittent short course antituberculosis regimen was satisfactory, the overall outcome was adversely affected by the high mortality (during and after completion of treatment) and recurrence rate among HIV-infected patients with tuberculosis. Immune status deteriorated in spite of antituberculosis treatment, highlighting the need for antiretroviral treatment in addition to antituberculosis treatment to improve the long term outcome. The results of this pilot study need to be confirmed by larger studies