Nomad: A Personal Journey through the Clash of Civilizations, by Ayaan Hirsi Ali; HarperCollins, 2010, 304 pages, $35. Few have experienced a more precipitous learning curve than Ayaan Hirsi Ali. Somalia’s most famous (or notorious, depending on your perspective) emigrant has completed a second autobiography, Nomad, at the relatively young age of forty. If her life continues to be as eventful as it has been until now—and her round-the-clock security regime does its job properly—we may see many more memoirs penned by the brave and articulate Hirsi Ali.                  During her childhood Hirsi Ali found herself living not only in Somalia…