Recently we proved with Durcik, Kovac, Skreb variational estimates providing sharp quantitative norm convergence results for bilinear ergodic averages with respect to two commuting transformations. The proof uses so called twisted technology developed in recent years for estimating bi-parameter paraproducts. Another application of the technique is to cancellation results for simplex Hilbert transforms.
I will discuss some results and open questions related to transport properties of 1D quasiperiodic operators with absolutely continuous spectra, and their relations to integrable many-body systems. Most of the results will be based on https://arxiv.org/abs/1505.07150