TUESDAY NEWSDAY, IN BRIEF:
* Jonathan Chait in the disarray of the Senate Democrats.
* Obama's toughest critic? Might be Paul Krugman. More from Dan Froomkin here.
* Why the BBC rules: mapping the fall of Communism.
* Video games can improve your vision. And longer schooling in youth reduces dementia in old age.
* Oh, snap: MGK on the difference between Pixar and Dreamworks.