Papers by Indranath Chaudhuri
Recently, Lenski et al [1, 2, 3] have carried out several experiments on bacterial evolution. The... more Recently, Lenski et al [1, 2, 3] have carried out several experiments on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. They have further quantified the relative contributions of adaptation, chance and history to bacterial evolution. In this paper, we show that a modified M-trait Bak-Sneppen model can explain many of the experimental results in a qualitative manner.
We study the Gierer-Meinhardt model of reaction-diffusion on a site-disordered square lattice. Le... more We study the Gierer-Meinhardt model of reaction-diffusion on a site-disordered square lattice. Let p be the site occupation probability of the square lattice. For p greater than a critical value pc, the steady state consists of stripe-like patterns with long-range connectivity. For p < pc, the connectivity is lost. The value of pc is found to be much greater than that of the site percolation threshold for the square lattice. In the vicinity of pc, the cluster-related quantities exhibit power-law scaling behaviour. The method of finite-size scaling is used to determine the values of the fractal dimension df, the ratio, γ ν, of the average cluster size exponent γ and the correlation length exponent ν and also ν itself. The values appear to indicate that the disordered GM model belongs to the universality class of ordinary percolation. PACS number(s): 05.70. Ln I.
Arxiv preprint cond-mat/9812243, 1998
We study the Gierer-Meinhardt model of reaction-diffusion on a site-disordered square lattice. Le... more We study the Gierer-Meinhardt model of reaction-diffusion on a site-disordered square lattice. Let p be the site occupation probability of the square lattice. For p greater than a critical value p c , the steady state consists of stripe-like patterns with long-range connectivity. For p < p c , the connectivity is lost. The value of p c is found to be much greater than that of the site percolation threshold for the square lattice. In the vicinity of p c , the cluster-related quantities exhibit power-law scaling behaviour. The method of finite-size scaling is used to determine the values of the fractal dimension d f , the ratio, γ ν , of the average cluster size exponent γ and the correlation length exponent ν and also ν itself. The values appear to indicate that the disordered GM model belongs to the universality class of ordinary percolation.
International Journal of Modern Physics C - IJMPC, 2001
Recently, Lenski et al \cite{Elena,Lenski,Travisano} have carried out several experiments on bact... more Recently, Lenski et al \cite{Elena,Lenski,Travisano} have carried out several experiments on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. They have further quantified the relative contributions of adaptation, chance and history to bacterial evolution. In this Brief Report, we show that a modified M-trait Bak-Sneppen model can explain many of the experimental results in a qualitative manner.
Universality and herd immunity threshold: Revisiting the SIR model for COVID-19
International Journal of Modern Physics C
COVID-19 pandemic has been raging all around the world for almost a year now, as of November 1, 2... more COVID-19 pandemic has been raging all around the world for almost a year now, as of November 1, 2020. In this paper, we try to analyze the variation of the COVID-19 pandemic in different countries in the light of some modifications to the susceptible-infected-recovered (SIR) model. The SIR model was modified by taking time-dependent rate parameters. From this modified SIR model, the basic reproduction number, effective reproduction number, herd immunity, and herd immunity threshold are redefined. The re-outbreak of the COVID-19 is a real threat to various countries. We have used the above-mentioned quantities to find the reasons behind the re-outbreak of this disease. Also, the effectiveness of herd immunity to prevent an epidemic has been analyzed with respect to this model. We have also tried to show that there are certain universal aspects in the spread and containment of the disease in various countries for a short period of time. Finally, we have also analyzed the current pande...
Physica A: Statistical Mechanics and its Applications, 1999
Recently, Lenski et al have carried out an experiment on bacterial evolution. Their findings supp... more Recently, Lenski et al have carried out an experiment on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. We show that the M=2 Bak-Sneppen model can explain some of the experimental results in a qualitative manner.
Physical Review E, 1997
We study the effect of randomness and anisotropy on Turing patterns in reaction-diffusion systems... more We study the effect of randomness and anisotropy on Turing patterns in reaction-diffusion systems. For this purpose, the Gierer-Meinhardt model of pattern formation is considered. The cases we study are (i) randomness in the underlying lattice structure; (ii) the case in which there is a probability p that at a lattice site both reaction and diffusion occur, otherwise there is
Uploads
Papers by Indranath Chaudhuri