ace MARCH 1997, PAGE 431 Convergent Multiplicative Processes Repelled from Zero: Power Laws and libuncated Power Laws Didier Sornette (I,2,') and Raina Cola (I) (I ) Laboratoire de Physique de la Matière Condensée ("), Université des Sciences, BP 70, Parc Valrose, 06108 Nice Cedex 2, France Department