Tour rocked by new positive tests Two Tour de France stage winners have tested positive for an advanced blood doping product. Italy's Leonardo Piepoli and Germany'sStefan Schumacher tested positive forContinuous Erythropoiesis ReceptorActivator (Cera).Italy's Riccardo Ricco has alreadyadmitted to using Cera, a version ofthe blood booster erythropoietin (EPO).Between them the three riders won fivestages during the July race - or abouta quarter of the 21 stages. How Ceefax switches to Digital TV 697