We present a formulation of branching and aging processes that allows age distributions along lineages to be studied within populations, and provides a new interpretation of classical results in the theory of aging. We establish a variational principle for the stable age distribution along lineages. Using this optimal lineage principle, we show that the response of a population's growth rate to...

An age-structured population is considered in which the birth and death rates of an individual of age a is a function of the density of individuals older and/or younger than a. An existence/uniqueness theorem is proved for the McKendrick equation that governs the dynamics of the age distribution function. This proof shows how a decoupled ordinary differential equation for the total population s...

in this study, some of biological parameters of vimba vimba from february 2009 to june 2010 were examined. in total, 281 fish samples were caught by gill- net. in two regions had of five age groups that, the most frequent age groups were related to 2+. sex ratio of male to female were in gorganrud population 67% ? to 33% ? and in mahmoudabad population 57% ? to 43% ? (p?0.05). there was no sign...