  A model for highly non-linear transport in heterogeneous media consisting of
anisotropic particles with a preferred orientation is proposed and applied to
the current transport in weakly textured magnesium diboride, MgB2. It
essentially explains why, unlike in conventional superconductors, a significant
macroscopic anisotropy of the critical currents can be induced by the
preparation of MgB2 tapes. The field and angular dependence of the critical
current is calculated for various degrees of texture and compared to
experimental data.
