![Comparison of evolution tracks calculated for models with mass $M = 15 M_\odot$ with (solid line) and without (dashed line) inward overshooting from the non-burning convective zone. OPAL opacity tables and metallicity $Z = 0.015$ were used.[]{data-label="fig2"}](fig2.eps){width="86mm"}

The presented examples show that properties of mixing, especially the convective overshooting, have a huge impact on the behaviour of the blue loops. It is difficult to discriminate between different effects but generally it seems that the inward overshooting from the outer convective zone on the RGB is indispensable to obtain blue loops for the models in the studied range of masses. The overshooting from the hydrogen core suspends the emerging of the blue loops and the overshooting from the helium core has a slight effect on their extension.

Instability domains
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For the models considered in Section2.1, we computed pulsational instability for modes with the degrees $\ell = 0, 1, 2$. They are shown as thick lines in in Fig.\[fig1\]. The top panels show models calculated with $Z=0.01$ and OPAL (the top-left panel) and OP opacity tables (the top-right panel). The central panels depicts models calculated for $Z=0.015$ and OPAL tables without and with mass loss (the central-left and central-right panels, respectively). 