Autocorrelation spectra of an air-fluidized granular system measured by NMR S. Lasič, J. Stepišnik, A. Mohorič, I. Serša and G. Planinšič Europhys. Lett., 75 6 (2006) 887-893 Published online: 11 August 2006 DOI: 10.1209/epl/i2006-10193-6