Plenary invited talk, 14th Canadian Conference on General Relativity and Relativistic Astrophysics, St. Johns, Newfoundland (July 11, 2012)

Black Holes VIII, Niagara Falls, Canada (May 13, 2011)

Colloquium, Dept of Math & Stats, Univ of New Brunswick (23 Oct, 2008)

Cosmo 2008, Univ of Wisconsin, USA (26 Aug, 2008)

Colloquium, Dept of Physics, Univ of New Brunswick (Jan 25, 2008)

Invited lectures, 4th Aegean Summer School, Greece (Sept 21-22, 2007)

Cosmo 2007, Univ of Sussex, Brighton, UK (21 Aug, 2007)