The collaboration is happening. The way we collaborate is through scientific journal articles. The communications are peer reviewed. There are articles that go back and forth in which findings are concurred with or disputed. That's the way the collaboration occurs. Periodically in the U.S. there are meetings where DU is discussed, but other than the normal communications that happen between people who are studying the same thing, the primary way is through the literature.
On March 19th, 2013. See this statement in context.