My girlfriend is working tonight, in casualty in the UK.  Emergency Room in America.  Not surprisingly, she had today off, but got called in to fill in.  She called me as she got there, telling me about the seven ambulances sitting outside, knowing its going to be an ugly queue inside.<p>Some days she gets there and finds a five hour wait, which they work hard to get down to a sensible level.  Traffic is variable, often seemingly random, and not just number of people.  Different kinds of problems need different kinds of solutions.<p>Some days she tells me about the number of people who died on her.  Those are the hard nights.  It's a hard job.  It's not a job that lends itself to predictability.