The following items determine whether a good a service has elastive demand:
C. Availability of substitutes for a good or service
A. If the good is a necessity of luxury.
There is not a specific antonym for diaspora, but the opposite of a diaspora would be the regrouping of a community or the coming together of a community. It could also be a renewal of a specific cultural group or ethnicity coming back together in a sort of revival of their culture.
This one is pretty easy, emperor Constsntine, I think that's how you spell his name.
