The office has the look and feel of an Internet start-up. The workers are young, the dress is casual and the computer of choice is an Apple notebook. They inhabit a single open room. The walls have whiteboards for scribbling ideas when inspiration strikes. But the office in Manhattan is not dedicated to the latest app. It is the base camp of the United Nations Global Pulse team — a tiny unit inside an institution known for its sprawling bureaucracy, not its entrepreneurial hustle.