[youtube]http://www.youtube.com/watch?v=E2FlcRVTuCA[/youtube]Mos Def will take part in Gulf Aid Sunday at Mardi Gras World River City on the Uptown side of the Convention Center. Here he samples Juvenile’s “Nolia Clap” for “Katrina Klap (Dollar Day),” his outraged take on the government’s slow response to post-K flooding.