Substitutions, tiling dynamical systems and minimal self-joinings

We investigate substitution subshifts and tiling dynamical systems arising from the substitutions (1) \theta : 0 \rightarrow 001,1 \rightarrow 11001 and (2) \eta : 0 \rightarrow 001,1 \rightarrow 11100. We show that the substitution subshifts arising from \theta and \eta have minimal self-joinings and are mildly mixing. We also give a criterion for 1-dimensional tiling systems arising from \theta or \eta to have minimal self-joinings. We apply this to obtain examples of mildly mixing 1-dimensional tiling systems.