  Using the flatification by blow-up result of Raynaud and Gruson, we obtain
new results for submersive and subtrusive morphisms. We show that universally
subtrusive morphisms, and in particular universally open morphisms, are
morphisms of effective descent for the fibered category of etale morphisms. Our
results extend and supplement previous treatments on submersive morphisms by
Grothendieck, Picavet and Voevodsky. Applications include the universality of
geometric quotients and the elimination of noetherian hypotheses in many
instances.
