Growth of velocity norms in Navier--Stokes flows, Clay Mathematics Institute Workshop on Geometry and Fluids (Oxford, April 2014); Global regularity of MHD turbulence with partial hyperdissipation, IUTAM Symposium on Understanding Common Aspects of Extreme Events in Fluids (Dublin, July 2012); A dynamical systems approach to fluid turbulence, Fourth International Symposium on Bifurcations and Instabilities in Fluid Dynamics (Barcelona, July 2011); A quantitative description of turbulence, Canadian Mathematical Society Meeting (Edmonton, June 2011); The number of degrees of freedom of three-dimensional Navier--Stokes turbulence, Fields Institute Workshop on the Dynamics in Environmental and Geophysical flows (Waterloo, July 2009)