Rights:
© 2009 American Physical Society (APS). This is the accepted version of the following article: Bonachela, Juan A. & Alava, Mikko J. & Muñoz, Miguel A. 2009. Cusps, self-organization, and absorbing states. Physical Review E. Volume 79, Issue 5. 050106/1-4. ISSN 1539-3755 (printed). DOI: 10.1103/physreve.79.050106, which has been published in final form at http://journals.aps.org/pre/abstract/10.1103/PhysRevE.79.050106.