We introduce mathematical methods for reducing complexity of deep neural networks 
in the context of computer vision for mobile and IoT applications such as sparsification and differentiable architecture search. We also describe applications in infectious disease prediction, and a deep learning and optimal 
transport (the deep particle) method in predicting invariant measures of 
stochastic dynamical systems arising in partial differential 
equation (PDE) modeling of transport in chaotic flows (e.g. rapid stirring of coffee and milk, raging forest fires in the wind). 

Living cells exhibit many forms of spatial-temporal dynamics, including recently-discovered traveling waves. Cells use these traveling waves to organizer their insides, to improve cell-cell communication, and tune their ability to move around the body. Some of these traveling waves arise from excitability (positive feedback) and non-local coupling (dynamics that spread spatially on timescales much faster than the timescale of wave motion). In collaboration with graduate students at UC Irvine, our research has studied two traveling waves involving the mechanics of the cytoskeletal protein actin: one that is approximately equivalent to a reaction-diffusion system [Barnhart et al, 2017, Current Biology], and one that is not [Manakova et al, 2016, Biophys J]. For the non-reaction-diffusion wave, we demonstrate conditions for wave travel analogous to ones previously derived for reaction-diffusion waves. We also demonstrate the existence of a "pinned" regime of parameter space absent in the equivalent reaction-diffusion system.

I will talk about some challenging problems and the role of Fourier concentration in an emerging field called learning theory. Suppose we want to learn a certain data. The basic question we ask is what is the minimal amount of information needed  to learn (predict)  the data with high precision and probability, and what is the role of Fourier analysis in these questions.