deletions | additions       diff --git a/Swimmers.tex b/Swimmers.tex  index a7cecd0..b57df78 100644  --- a/Swimmers.tex  +++ b/Swimmers.tex 
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\begin{enumerate}  \item Why do the swimmers float on top?  \item For now consider the simple case of a single swimmer inert particle  in a concentration gradient. Say it moves towards the source of the chemical. It will follow some mean trajectory, but with plenty of scatter. This is an out-of-equilibrium process. \begin{enumerate}  \item Which part is out of equilibrium?  \item What does the scatter in trajectories tell us about the system? Anything useful? Use linear-response theory (is this justified? Why?).  \end{enumerate}   \item Then consider a single active swimmer in a concentration gradient. Get superposition of two behaviours.  \end{enumerate}