Results for selected intermediate-mass AGB models with and without the inclusion of PMZs. The solid lines represent model predictions without the inclusion of a PMZ, the dashed line models with a PMZ of 1 × 10^-4 M_⊙. The observed [Rb/Fe] and [Zr/Fe] ranges are indicated by the grey shaded area, note that [Rb/Fe] ranges up to 2.5 (±0.8, see Table 1). (This figure is available in color in the electronic form.)