Behringer, RP; Chakraborty, B; Henkes, S, *Why Do Granular Materials Stiffen at Faster Shear Rates? A Test of Novel Stress-Based Statsitical Mechanics*,
Phys. Rev. Lett., vol. 101 no. 26
(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).*