Welcome back to the work week, D.C. While some may have been celebrating the arrival of Christopher Columbus to the Americas yesterday, others were protesting for one cause or another. Students at American University organized to push for president Ben Ladner’s dismissal (which came last night), while anti-circumcision activists, at right, took to the streets outside the Washington Convention Center, where the American Academy of Pediatrics was meeting (yes, we will have a full write-up…