and temperature dependence of $R_{\infty}$ is in good agreement with this expectation.

![Top: time dependence of the asymptotic structure factor $R_{\infty}$ at a temperature of 1200 K, full line: slope 0.25 of the double-logarithmic plot; bottom: temperature dependence of $R_{\infty}$ at time $3ns$, full line: slope 0.25 of the double-logarithmic plot. \[fig:rtimetemp\]](Rtimetemp.pdf){width="3.3in"}

A generic representation of the roughening behavior at all times and all temperatures is obtained by introducing the new variables $u = d({\cal T} t/B)^{-1/z}$ and $w = R (k_{\rm B}T)^{-\zeta} B^{\zeta/z} {\cal T}^{\zeta(z-1)/z} t^{-\zeta/z}$ in which the structure factor has the universal form $$w = u^{\zeta} \Phi(u^{-z}).$$ This is illustrated in Figure \[fig:rougheningT\], bottom, which shows a compilation of structure factor curves pertaining to different temperatures and roughening times after re-scaling to the universal variables $u$ and $w$. The plot demonstrates the existence of an underlying generic scaling curve that represents the evolving shapes at all times and temperatures.

Roughening and pinning in a spatially random force field {#sec:4.2}
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In this section, we investigate the interaction of a dislocation with a spatial time-independent force field. Spatially random force fields can be used to model structural disorder on the atomic scale as prominent in random solid solutions 