Upper panels: [Ba/Si] versus age trend in the inner, solar, and outer regions. The observational data trend is represented by the logarithmic fit with the associated 1σ error bar curve. The result of Model 2 is shown by the black line. The dashed black and yellow lines represent Model 2 with reduced s-process production and its associated residual curve. Bottom panel: absolute abundance of Ba as predicted by the reduced Model 2 (dashed black line) together with the computed missing abundance of Ba in the age ranges of interest (see text for details).