When Benoit Mandelbrot discussed the problem of fractional Brownian mo
tion in his classic book The Fractal Geometry of Nature, he already po
inted out some strong relations to the Riemann-Liouville fractional in
tegral and differential calculus. Over the last decade several papers
have appeared in which integer-order, standard differential equations
modeling processes of relaxation, oscillation, diffusion and wave prop
agation are generalized to fractional order differential equations. Th
e basic idea behind all that is that the order of differentiation need
not be an integer but a fractional number (i.e. d(q)/dt(q) with 0 < q
< 1). Applications to slow relaxation processes in complex systems li
ke polymers or even biological tissue and to selfsimilar protein dynam
ics will be discussed. In addition, we investigate a fractional diffus
ion equation and we present the corresponding probability density func
tion for the location of a random walker on a fractal object. Fox-func
tions play a dominant part.