Bulbul Chakraborty

3Silke Henkes
3Dapeng Bi
3Allison Ferguson
3Corey S O'Hern
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A field theory of frictionless grain packings in two dimensions is shown to exhibit a zero-temperature critical point at a nonzero value of the packing fraction. The zero-temperature constraint of force balance plays a crucial role in determining the nature of the transition. Two order parameters, <z>, the deviation of the average number of contacts from(More)
We construct a statistical framework for static assemblies of deformable grains which parallels that of equilibrium statistical mechanics but with a conservation principle based on the mechanical stress tensor. We define a state function that has all the attributes of entropy. In particular, maximizing this function leads to a well-defined granular(More)
A broad class of disordered materials including foams, glassy molecular systems, colloids and granular materials can form jammed states. A jammed system can resist small stresses without deforming irreversibly, whereas unjammed systems flow under any applied stresses. The broad applicability of the Liu-Nagel jamming concept has attracted intensive(More)
In this paper we report the results of simulations of a 2D gravity driven, dissipative granular flow through a hopper system. Measurements of impulse distributions P (I) on the simulated system show flow-velocity-invariant behavior of the distribution for impulses larger than the average impulse < I >. For small impulses, however, P (I) decreases(More)
We study the appearance of large-scale dynamical heterogeneities in a simplified model of a driven, dissipative granular system. Simulations of steady-state gravity-driven flows of inelastically colliding hard disks show the formation of large-scale linear structures of particles with a high collision frequency. These chains can be shown to carry much of(More)
We study a one-dimensional model of microtubule assembly and disassembly in which GTP bound to tubulins within the microtubule undergoes stochastic hydrolysis. In contrast to models that consider only a cap of GTP-bound tubulin, stochastic hydrolysis allows GTP-bound tubulin remnants to exist within the microtubule. We find that these buried GTP remnants(More)
We study numerically frictionless ellipse packings versus the aspect ratio alpha, and find that the jamming transition is fundamentally different from that for spherical particles. The normal mode spectra possess two gaps and three distinct branches over a range of alpha. The energy from deformations along modes in the lowest-energy branch increases(More)
ACKNOWLEDGEMENTS Many people have enabled me to pursue my graduate work at Brandeis. First among these is my thesis advisor Prof. Seth Fraden, who brought me into his laboratory despite my utter lack of experimental skills. His direction and knowledge were an invaluable part of my time at Brandeis. He always encouraged and supported my experimental work and(More)
Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a nonuniform density pattern. In this work, we focus on the emergence of shear rigidity in a class of solids where this paradigm is challenged. Dry granular(More)