Dear friends and colleagues, on Monday, 4 April 2016, 2-3pm Yihong Du (University of New England, Armidale) is giving a talk in the PDE Seminar with the above-given title. An abstract is available at http://www.maths.usyd.edu.au/u/PDESeminar/abstracts16/du.xhtml The talk is in Carslaw, level 8, Rm 829 (AGR) at the University of Sydney. Everybody is invited to attend the talk and take part at the discussion afterwards in Carslaw Common Room 727 on level 7. Kind regards, Daniel D and Daniel H P.S: If you know suitable speakers or want to give a talk yourself, please let us know.