arXiv subjects

Supurna Sinha

Publications and source records attributed to Supurna Sinha.

62 records · Page 4Linked to original sources

arXiv2004

Dynamics of Vibrated Grains

We study number density distribution and the behavior of time correlation functions in the density of grains for a quasi-two dimensional system of vibrated grains. We study the system at various packing fractions, from low to high. At low densities we recover usual gas like behavior, reflected in a Poissonian statistics for the number density distribution. At higher densities we notice effects like formation of cages of the kind that are seen in glass transition.

cond-mat.soft↗

arXiv2004

The Writhe Distribution Of Stretched Polymers

Motivated by experiments in which single DNA molecules are stretched and twisted we consider a perturbative approach around very high forces, where we determine the writhe distribution in a simple, analytically tractable model. Our results are in agreement with recent simulations and experiments.

cond-mat.soft↗

arXiv2003

Onset of Shear Waves In A Bacterial Bath: A Novel Effect

Recent experiments on particle diffusion in bacterial baths indicate the formation of correlated structures in the form of bacterial swirls. Here we predict that such a structural ordering would give rise to the new effect of propagating shear waves in a bacterial bath at length scales of the order of a swirl, which corresponds to time scales of the order of the lifetime of a swirl. Our prediction can be tested against future experiments in bacterial baths.

cond-mat.soft↗

arXiv2003

Biopolymer Elasticity

In recent years molecular elasticity has emerged as an active area of research: there are experiments that probe mechanical properties of single biomolecules such as DNA and Actin, with a view to understanding the role of elasticity of these polymers in biological processes such as transcription and protein-induced DNA bending. Single molecule elasticity has thus emerged as an area where there is a rich cross-fertilization of ideas between biologists, chemists and theoretical physicists. In this article we present a perspective on this field of research.

physics.ed-ph↗

arXiv2003

Molecular elasticity and the geometric phase

We present a method for solving the Worm Like Chain (WLC) model for twisting semiflexible polymers to any desired accuracy. We show that the WLC free energy is a periodic function of the applied twist with period 4 pi. We develop an analogy between WLC elasticity and the geometric phase of a spin half system. These analogies are used to predict elastic properties of twist-storing polymers. We graphically display the elastic response of a single molecule to an applied torque. This study is relevant to mechanical properties of biopolymers like DNA.

cond-mat↗

arXiv2002

Elasticity of semi-flexible polymers

We present a numerical solution of the Worm-Like Chain (WLC) model for semi-flexible polymers. We display graphs for the end-to-end distance distribution and the force-extension relation expected from the model. We predict the expected level of fluctuations around the mean value in force-extension curves. Our treatment analyses the entire range of polymer lengths and reproduces interesting qualitative features seen in recent computer simulations for polymers of intermediate length. These results can be tested against experiments on single molecules. This study is relevant to mechanical properties of biological molecules.

cond-mat.soft↗

arXiv2000

Brownian Motion on a Sphere: Distribution of Solid Angles

We study the diffusion of Brownian particles on the surface of a sphere and compute the distribution of solid angles enclosed by the diffusing particles. This function describes the distribution of geometric phases in two state quantum systems (or polarised light) undergoing random evolution. Our results are also relevant to recent experiments which observe the Brownian motion of molecules on curved surfaces like micelles and biological membranes. Our theoretical analysis agrees well with the results of computer experiments.

cond-mat↗

arXiv1997

Thomas Rotation and Polarised Light: A non-Abelian Geometric Phase in Optics

We describe a non-Abelian Berry phase in polarisation optics, suggested by an analogy due to Nityananda between boosts in special relativity and the effect of elliptic dichroism on polarised light. The analogy permits a simple optical realization of the non-Abelian gauge field describing Thomas rotation. We also show how Thomas rotation can be understood geometrically on the Poincaré sphere in terms of the Pancharatnam phase.

quant-ph↗