SEMINAR INFORMATION

Title: Stochastic approach to complex systems modeling

Speaker: ATHOKPAM Langlen Chanu*

*Asia Pacific Center for Theoretical Physics (APCTP)

As the 21st century unfolds, complexity is starting to rule everywhere, from cells to societies to the universe. Complexity is profound in nature, society, technology, and data. We can broadly look at complex systems from three angles: dynamics, networks, and data. Stochastic processes are used to study the dynamical properties of various complex systems at varying scales ranging from gene expression, protein structural dynamics, metabolic pathways, biochemical reaction networks, disease dynamics, social dynamics to astrochemical dynamics. In this talk, I will present a stochastic approach to studying various complex systems using the chemical Master equation formalism and stochastic simulation methods. A stochastic approach can reveal hidden dynamical patterns and behaviors, especially the roles of fluctuations in the system dynamics. We found that stochastic fluctuations play important roles, such as the emergence of demographic stochasticity in epidemics or noise enhancement in a non-equilibrium autocatalytic chemical reactions system. Biological cells are complex biochemical systems that are open systems where many biological activities are contributed by different transport processes and non-linear chemical reactions. They exhibit far from equilibrium dynamics. Again, complex biological systems generally show non-Markovian dynamics. Time delay, a non-Markovian character, is found to have multi-functional roles in complex biological systems. Inside a biological cell, biomolecular processes function far from equilibrium by consuming free energy out of the ATP hydrolysis cycle and are dissipative. This naturally leads to a free-energy cost. The Thermodynamic Uncertainty Relation (TUR) is a fundamental relation between the free-energy cost of maintaining such non-equilibrium processes and the relative uncertainty in the random variable quantifying the output of such processes. In this talk, I will present the investigation of the TUR in a biological model system of interlinked cascades.