Specific growth rate
= Specific growth rate
{title2=$\mu$}
The <specific growth rate> is biomass production per unit existing biomass per unit time. For <biomass concentration> $x>0$ with growth alone, $\dot x=\mu x$ and $\mu=\mathrm{d}(\ln x)/\mathrm{d}t$. A constant positive <specific growth rate> produces <exponential growth>, $x(t)=x(0)e^{\mu t}$, with doubling time $\ln2/\mu$. In a <chemostat>, removal makes the net rate $\dot x/x=\mu(s)-D$, rather than $\mu(s)$ itself.