Mass fraction produced by the s-process channel of production (top panels) and [X/Eu] vs [Fe/H] (bottom panels) for Zr (left panels), Ba (central panels) and La (right panels) for models with different IMFs. In the top panels, we show the results for models adopting the reference Kroupa (2001) IMF (thin dash-dotted lines), Kroupa et al. (1993) IMF (thin dashed), and a modified a top-light IMF (thick solid). In the bottom panels, blue solid lines an cyan shaded regions are genuine chemical tracks and predictions accounting for observational uncertainties ('synthetic model') for a model with a top-light IMF. Data include the Solar s-process mass fraction (Sneden et al. 2008, top panels) and those shown in Fig. 5 (bottom panels).