Instabilities in vertically vibrated fluid-grain systems P. J. King, P. Lopez-Alcaraz, H. A. Pacheco-Martinez, C. P. Clement, A. J. Smith and M. R. Swift Eur. Phys. J. E, 22 3 (2007) 219-226 Published online: 17 January 2007 DOI: 10.1140/epje/e2007-00001-6