om 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 of Earth and Space Science. and Institute of Geophysics and Planetary Physics, Univers