arXiv subjects

Sudipto Muhuri

Publications and source records attributed to Sudipto Muhuri.

22 records · Page 2Linked to original sources

arXiv2011

Phase segregation and transport in a two species multi-lane system

We present a two channel driven lattice gas model with oppositely directed species moving on two parallel lanes with lane switching processes. We study correlated lane switching mechanism for particles so that switching may occur with finite probability only when oppositely directed species meet on the same channel. The system is analyzed for closed ring with conserved total particle number. For asymmetric particle exchange between the lanes, the system exhibits unique polarization phenomenon with segregation of oppositely directed species between the two lanes. The polarization phenomenon can be understood as a consequence of existence of an absorbing steady state. For symmetric exchange rate of particles between the lanes, the system remains unpolarized, with equal particle density on both the lanes in the thermodynamic limit of large system size. We study the system using a combination of a Mean Field(MF) analysis and Monte Carlo simulations. The nature of phase segregation that we see for this system, is distinct from driven particle systems which are in contact with particle reservoir. The features observed for this minimal model will have ramifications for biofilament based intracellular transport, wherein cellular cargo, e.g; organelles and vesicles are transported by oppositely directed particles on multiple filament tracks.

cond-mat.stat-mech↗

arXiv2011

Bidirectional transport in a multispecies TASEP model

We study a minimal lattice model which describes bidirectional transport of "particles" driven along a one dimensional track, as is observed in microtubule based, motor protein driven bidirectional transport of cargo vesicles, lipid bodies and organelles such as mitochondria. This minimal model, a multi-species totally asymmetric exclusion process (TASEP) with directional switching, can provide a framework for understanding the interplay between the switching dynamics of individual particles and the collective movement of particles in 1-dimension. When switching is much faster than translocation, the steady state density and current profiles of the particles are homogeneous in the bulk and are well described by a Mean-Field (MF) theory, as determined by comparison to a Monte Carlo simulation. In this limit, we construct a non-equilibrium phase diagram. Away from this fast switching regime, the MF theory fails, although the average bulk density profile still remains homogeneous. We study the steady state behaviour as a function of the ratio of the translocation and net switching rates, Q, and find a unique first-order phase transition at a finite Q associated with a discontinuous change of the bulk density. When the switching rate is decreased further (keeping translocation rate fixed), the system approaches a jammed phase with a net current that tends to zero as J ~ 1/Q.

cond-mat.stat-mech↗

arXiv2010

Lattice-gas model for active vesicle transport by molecular motors with opposite polarities

We introduce a multi-species lattice gas model for motor protein driven collective cargo transport on cellular filaments. We use this model to describe and analyze the collective motion of interacting vesicle cargoes being carried by oppositely directed molecular motors, moving on a single biofilament. Building on a totally asymmetric exclusion process (TASEP) to characterize the motion of the interacting cargoes, we allow for mass exchange with the environment, input and output at filament boundaries and focus on the role of interconversion rates and how they affect the directionality of the net cargo transport. We quantify the effect of the various different competing processes in terms of non-equilibrium phase diagrams. The interplay of interconversion rates, which allow for flux reversal and evaporation/deposition processes introduce qualitatively new features in the phase diagrams. We observe regimes of three-phase coexistence, the possibility of phase re-entrance and a significant flexibility in how the different phase boundaries shift in response to changes in control parameters. The moving steady state solutions of this model allows for different possibilities for the spatial distribution of cargo vesicles, ranging from homogeneous distribution of vesicles to polarized distributions, characterized by inhomogeneities or {\it shocks}. Current reversals due to internal regulation emerge naturally within the framework of this model. We believe this minimal model will clarify the understanding of many features of collective vesicle transport, apart from serving as the basis for building more exact quantitative models for vesicle transport relevant to various {\it in-vivo} situations.

cond-mat.stat-mech↗

arXiv2006

Shear flow induced isotropic to nematic transition in a suspension of active filaments

We study the effects of externally applied shear flow on a model of suspensions of motors and filaments, via the equations of active hydrodynamics [PRL {\bf 89} (2002) 058101; {\bf 92} (2004) 118101]. In the absence of shear, the orientationally ordered phase of {\it both} polar and apolar active particles is always unstable at zero-wavenumber. An imposed steady shear large enough to overcome the active stresses stabilises both apolar and moving polar phases. Our work is relevant to {\it in vitro} studies of active filaments, the reorientation of endothelial cells subject to shear flow and shear-induced motility of attached cells.

cond-mat.soft↗