LaViolette predicted quasars as short-term phenomenon. He confirms this prediction published in his dissertation in 1983. He remarks that it is related to galactic core outbursts, such as have occurred in our galaxy, the latest of which shut off around 10-11,000 years ago. New evidence confirms this short period cycle: http://www.physorg.com/news/2010-11-cosmic-curiosity-reveals-ghostly-dead.html
More about this is discussed in the Starburst superwave forum.