Xiu Xiu specializes in a rutty brand of noise pop that relies on the most extreme feelings for impact-a kind of bipolar pathos music. As such, Jamie Stewart's catalog tends to ricochet between opposite ends of a diseased spectrum. On The Air Force, the group loads a half hour with unchecked fits and medicated slogs that recalibrate with a remarkable fluidity. It's only seconds of pretty piano before off-kilter percussion stabs and jagged sub-bass lead everything into a train wreck of atonal harmonies and unsettling silence. Naturally, such a depressive and exhaustive M.O. demands a lot, but the unpacking is well worth it.