There are a few shifts between the two parts of this novel. When part two begins, there is of course a shift in setting. Julius is on a plane that is about to land in New York after using all of his vacation days in Europe. But the character of Julius has changed as well. As part two develops, the people and environment around him make him increasingly anxious about his mortality and fragility. Note the foreshadowing at the beginning of chapter 12, the first chapter in the second part:

The weeks to come were going to be difficult (152).

While Julius thinks this in reference to the next few weeks at work, the reader soon sees that it applies to other parts of his life as well. It’s almost as if the time he spent away from the city made him feel like things were happening too fast when he returned. Consider how he notes Professor Saito's intense pain and the advancement of Saito's nurse's pregnancy. And after Nadege calls and tells Julius she is engaged, he says:

I had the ulcerous sensation of too many things happening at once (184).

Here we see that Julius feels increasingly overwhelmed in the second part of the novel. As many negative events occur in his world, he begins to feel himself slipping out of control as well. For example, he cannot recall his ATM pin for weeks, and becomes incredibly anxious about aging. He becomes paranoid about bedbug infestations, Professor Saito dies, and he gets beat up so badly on the street that he needs surgery. The rapid, flurrying pace of events in the second part marks Julius’s realization that life inevitably moves with his participation or without it.