dramatic reversal just now for the entire lower end of the stack.  4.5's shot up 6 ticks in very short order.  Now down only 2 ticks on the day at 101-15.  4.0's unchanged on the day, just over 100-02.  5.0's down only 2 ticks at 102-15.  Possible Fed buying the culprit, and if that doesn't turn out to be the case, even better, as the market itself would have basically just marked this morning's lows as a buying point.  Whatever the case, stay tuned for additional devlopments on this volatile day.