When the world last came together for the Winter Olympics, Russia was in the doghouse because of doping. Jacques Rogge, then head of the International Olympic Committee, was so unhappy about a string of doping positives in Russian cross-country skiing and biathlon that he publicly upbraided the 2014 Olympic host, demanding that it "respond with strong anti-doping actions" and disclosing that he had voiced his concerns directly to Dmitry Medvedev, then Russia's president. In the four years since, and as part of its preparations to host the games that open Feb. 7 in Sochi, Russia has dramatically improved its anti-doping regime, say outside experts working with the Russians on that effort.