Integrated Calendar

Living in a social environment involves diverse types of interactions between members of the same species that are essential for the health, survival, and reproduction of animals. The intricate nature of social interaction requires the ability to identify and recognize other members of the group in the right context, season, sex, age and reproductive state, and to respond appropriately to different social encounters.We study mechanisms that shape social interaction in Drosophila melanogaster and investigate the ways by which social interaction modulates motivational states and leads to different action selection in subsequent social encounters.

Shape transitions in developing organisms can be driven by active stresses, notably, active contractility generated by myosin motors. We study the contraction and buckling of actomyosin networks isolated from bounding surfaces as a model system for studying shape transitions in developing tissues. This system offers a well-controlled way to study the role of physical constraints and boundary conditions mechanically induced spontaneous shape transition.

Grain boundaries (GBs) are the 2D interfaces between crystals of the same material with different orientations. The dynamics of GBs is central to both microstructure evolution and the mechanics of polycrystals. GB dynamics are largely controlled by the motion of line defects that are constrained to lie in the GB. These line defects, known as disconnections, have both dislocation character (Burgers vector) and step character (step height). Possible Burgers vectors and step heights are completely determined by crystallography (i.e., crystal structure and the relative orientations of the two grains). In this talk, I will discuss disconnections, their crystallography, their nucleation and motion, and present a statistical mechanics-based description of a wide range of GB properties based on disconnection dynamics. In particular, I will discuss the thermal roughening of GBs, the migration of GBs, GB shear coupling, and how GBs interact with with applied stresses and compare these predictions with both molecular dynamics and experimental results. I will end by describing the remaining challenges in developing a quantitative approach to the microstructure evolution of polycrystalline materials.