Jamming and critical outlet size in the discharge of a two-dimensional silo A. Janda, I. Zuriguel, A. Garcimartín, L. A. Pugnaloni and D. Maza EPL, 84 4 (2008) 44002 Published online: 12 November 2008 DOI: 10.1209/0295-5075/84/44002