Abstract : Collective cell dynamics exists extensively and plays key regulating roles in vast physiological or pathological processes including embryo development, wound healing, and tumor invasion. It involves the dynamic self-assembly of intracellular cytoskeleton, the regulation of biochemical signaling pathways, as well as the interactions among cells and those between cells and microenvironment, making it a challenging frontier topic in biophysics. Via combining experiments, theory, and simulations, I study collective cell dynamics in confluent cell monolayer systems. In this talk, I’ll present my primary research on collective cell dynamics during my PhD career. My work can be mainly divided into three parts as below.
Firstly, I investigate the velocity distribution statistics of collective cell migration in 2D cell monolayer systems. Through live-cell imaging experiments and PIV analysis, I find that cell velocities in 2D monolayers obey the q-Gaussian distribution. The velocity distribution statistics keeps almost invariant during the jamming transition of cell monolayers and has no apparent dependence on cell type and substrate stiffness, revealing its universality.
Secondly, collective cell migration on both planar and curved substrates are studied based on a proposed active vertex model. The regulating roles of intercellular social interactions and geometric constraints on collective migration modes, characteristic scales, and density fluctuations in cell monolayers are elucidated.
Thirdly, a chemomechanical model is established to investigate the collective morphodynamics in 2D cell monolayer systems. Taking the collective shape oscillations in Drosophilaamnioserosa as a typical example, I study the pattern, polarization, and synchronization of collective cell oscillations. Further, the regulating roles of mechanical forces and boundary constraints are deciphered.

A new quantization prescription is able to endow quantum field theory with a new type of "particle", the fakeon (fake particle), which mediates interactions, but cannot be observed. A massive fakeon of spin 2 (together with a scalar field) allows us to build a theory of quantum gravity that is both renormalizable and unitary, and to some extent unique. After presenting the general properties of this theory, I discuss its classical limit, which carries important remnants of the fakeon quantization prescription. I also discuss the possibility that the Higgs boson might be a fakeon.