Behringer, RP; Bi, D; Chakraborty, B; Henkes, S; Hartley, RR, *Why do granular materials stiffen with shear rate? Test of novel stress-based statistics.*,
Physical Review Letters, vol. 101 no. 26
(December, 2008),
pp. 268301 [19437678], [doi] .
**Abstract:**

*Recent experiments exhibit a rate dependence for granular shear such that the stress grows linearly in the logarithm of the shear rate, gamma. Assuming a generalized activated process mechanism, we show that these observations are consistent with a recent proposal for a stress-based statistical ensemble. By contrast, predictions for rate dependence using conventional energy-based statistical mechanics to describe activated processes, predicts a rate dependence of (ln(gamma))(1/2).*