Whether you are a homeland security pundit, closet xenophobe, or simply a concerned Washingtonian, odds are you were at least a little alarmed by the recently announced acquisition of P&O Ports by Dubai Ports World, a shipping firm owned and operated by the government of the United Arab Emirates. The acquisition has local ramifications — P&O Ports operate Baltimore’s port. Lest we become too comfortable with our port-less city economy, we mustn’t forget that we…