= Monotone Jeans growth with positive cosmological constant
If $\eta^2=-s^2<0$, $\delta(0)>0$ and $\dot\delta(0)\geq0$, the <integrating factor> identity $(e^{2\mu t}\dot\delta)'=s^2e^{-\mu t}\delta$ proves that $\delta$ stays positive and increases. Its finite limit satisfies $\delta_\infty=\delta(0)+\dot\delta(0)/(2\mu)+s^2\int_0^\infty e^{-3\mu t}\delta(t)dt/(2\mu)>\delta(0)$. The initial sign condition is essential: the positive decaying <modified Bessel function> mode has limit zero.
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