Quasistationarity in a Branching Model of Division-Within-Division

Many biological processes include branching phenomena, which may be called division-within-division. Examples are gene amplification in cancer cells and elsewhere, plasmid dynamics in bacteria, and proliferation of viral particles in host cells. In some cases, the loss of “smaller” particles from the “large” ones leads to extinction of the latter. The logical question is then to ask about the distribution of the nonextinct particles, which mathematically leads to the consideration of quasistationarity, ie. stationarity of the process conditional on nonabsorption.