arXiv subjects

Soumitra Kolya

Publications and source records attributed to Soumitra Kolya.

4 recordsLinked to original sources

arXiv2026

Mode-coupling theory for aging in active glasses: relaxation dynamics and evolution towards steady state

Aging refers to the evolution of system properties with waiting time $t_w$. It is a key feature of glassy dynamics. Recent experiments have demonstrated aging in biological systems that are inherently active with a magnitude of self-propulsion force $f_0$ and a persistence time $\tau_p$. Thus, what governs the aging dynamics in these active systems has fundamental importance. We formulate a generic mode-coupling theory (MCT) of active glasses to address this question. The aging solutions of the theory show that the two-point correlation function decays more slowly with growing $t_w$, and the relaxation time $t_r$ increases. The activity-modification of the MCT critical point, $\lambda_\text{C}$, has profound significance for active aging: the quench distance from $\lambda_\text{C}$ governs aging and determines $\delta$, where $t_r\sim t_w^\delta$. $\delta$ decreases with increasing $f_0$, in agreement with existing simulations. However, the variation with $\tau_p$ depends on the nature of activity. Our work has fundamental theoretical implications for active glasses and paves the way for a deeper understanding of the aging dynamics in biological systems.

cond-mat.soft↗

arXiv2025

Glassy dynamics in active epithelia emerge from an interplay of mechanochemical feedback and crowding

Glassy dynamics in active biological cells remain a subject of debate, as cellular activity rarely slows enough for true glassy features to emerge. In this study, we address this paradox of glassy dynamics in epithelial cells by integrating experimental observations with an active vertex model. We demonstrate that while crowding is essential, it is not sufficient for glassy dynamics to emerge. A mechanochemical feedback loop (MCFL), mediated by cell shape changes through the contractile actomyosin network, is required to drive glass transition in dense epithelial tissues, as revealed via a crosstalk between actin-based cell clustering and dynamic heterogeneity in experiments. Incorporating MCFL into the vertex model reveals contrasting results from those previously predicted by theories -- we show that the MCFL can counteract cell division-induced fluidisation and enable glassy dynamics to emerge through active cell-to-cell communication. Furthermore, our analysis reveals, for the first time, the existence of novel collective mechanochemical oscillations that arise from the crosstalk of two MCFLs. Together, we demonstrate that an interplay between crowding and active mechanochemical feedback enables the emergence of glass-like traits and collective biochemical oscillations in epithelial tissues with active cell-cell contacts.

physics.bio-ph↗

arXiv2024

Active Inhomogeneous Mode-Coupling Theory (aIMCT) for Dense Systems of Self-Propelled Particles

Glassy dynamics in a dense system of active particles with self-propulsion force $f_0$ and persistence time $\tau_p$ are crucial for many biological processes. Recent studies have shown that, unlike relaxation dynamics, dynamic heterogeneity (DH) in active glasses exhibits nontrivial behavior. However, the mechanism by which activity affects DH remains unknown. We have developed an active inhomogeneous mode-coupling theory (aIMCT) for DH in active glasses. We show that the nontrivial behavior of DH comes from a novel nonequilibrium effect of activity that leads to distinct behaviors of DH and relaxation dynamics in active glasses. When activity is small, DH exhibits equilibrium-like behavior with a power-law divergence of the peak height of the four-point correlation function, $\chi_C^\text{peak}$, and the aIMCT value of the exponent, $\mu\simeq 1.0$, is consistent with the existing and our new simulations of active glasses. However, $\chi_C^\text{peak}$ deviates from the scaling relations at higher $f_0$ values because of the novel effect on DH, although the deviation with varying $\tau_p$ is relatively weak.

cond-mat.soft↗

arXiv2024

The structure-dynamics feedback mechanism governs the glassy dynamics in epithelial monolayers

The glassy dynamics in confluent epithelial monolayers is crucial for several biological processes, such as wound healing, embryogenesis, cancer progression, etc. Several experiments have indicated that, unlike particulate systems, the glassy dynamics in these systems correlates with the static properties and shows a readily-found sub-Arrhenius relaxation. However, whether the statics-dynamics correlation is only qualitative or can provide quantitative predictions and what leads to the sub-Arrhenius relaxation remains unclear. We apply a particular analytical theory of glassy dynamics, the mode-coupling theory (MCT) that predicts dynamics using static properties alone as input, to the confluent systems. We demonstrate the remarkable applicability of MCT in simulations of the Vertex model and experiments on Madin-Darby Canine Kidney cells and show the quantitative nature of the structure-dynamics correlation in these systems. Our results elucidate that the structure-dynamics feedback mechanism of MCT, and not the barrier crossing mechanism, dominates the glassy dynamics in these systems where the relaxation time diverges as a power law with a universal exponent of $3/2$. This slower-than-exponential divergence naturally explains the sub-Arrhenius relaxation dynamics in these systems. The quantitative nature of the structure-dynamics correlation also suggests the possibility of describing various complex biological processes, such as cell division and apoptosis, via the static properties of the systems, such as cell shape or shape variability.

cond-mat.soft↗