factor of 10 is derived to reduce the metallicity to 1-2 times solar. In recent simulations [@sca10] demonstrate that turbulent mixing can effectively drive a galactic wind. Although they stated that their models lead to a complex, chaotic distribution of bubbles, loops and filaments as observed in NGC 1569, other observational facts have not been compared.

Detailed numerical simulations of the chemical evolution of these SBDG by [@rec06b] could simultaneously reproduce both, the oxygen abundance in the warm gas as well as the metallicity in the hot outflow. Surprisingly, [@rec07a] demonstrated that the leakage of metals from a SBDG is not prevented by the presence of clouds because the clouds pierce holes into the wind shells. This leads to a final metallicity a few tenths of dex lower than in models without clouds.

Consequently, the crucial question must be answered which physical processes trigger such enormous SFRs as observed in SBDGs and consume all the gas content within much less than the Hubble time. One possibility which has been favoured until almost two decades ago was that at least some of these objects are forming stars nowadays for the very first time. Today it is evident that the most all 