  A general treatment of disk star formation is developed from a dissipative
multi-phase model, with the dominant dissipation due to cloud collisions. The
Schmidt-Kennicutt law emerges naturally for star-forming disks and starbursts.
We predict that there should be an inverse correlation between Tully-Fisher law
and Schmidt-Kennicutt law residuals. The model is extended to include a
multi-phase treatment of supernova feedback that leads to a turbulent
pressure-regulated generalization of the star formation law and is applicable
to gas-rich starbursts. Enhanced pressure, as expected in merger-induced star
formation, enhances star formation efficiency. An upper limit is derived for
the disk star formation rate in starbursts that depends on the ratio of global
ISM to cloud pressures. We extend these considerations to the case where the
interstellar gas pressure in the inner galaxy is dominated by outflows from a
central AGN. During massive spheroid formation, AGN-driven winds trigger star
formation, resulting in enhanced supernova feedback and outflows. The outflows
are comparable to the AGN-boosted star formation rate and saturate in the
super-Eddington limit. Downsizing of both SMBH and spheroids is a consequence
of AGN-driven positive feedback. Bondi accretion feeds the central black hole
with a specific accretion rate that is proportional to the black hole mass.
AGN-enhanced star formation is mediated by turbulent pressure and relates
spheroid star formation rate to black hole accretion rate. The relation between
black hole mass and spheroid velocity dispersion has a coefficient (Salpeter
time to gas consumption time ratio) that provides an arrow of time. Highly
efficient, AGN-boosted star formation can occur at high redshift.
