deletions | additions       diff --git a/Payam & DNA.tex b/Payam & DNA.tex  index 03e1e28..8e0936f 100644  --- a/Payam & DNA.tex  +++ b/Payam & DNA.tex 
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\item Dimensional analysis argument not fully understood: I guessed $t_{\rm h}\sim \ell/c_{\rm s}$ on physical grounds, but Payam says $t_{\rm h}\sim \ell^2\rho/\eta$ from dimensional analysis. What is the interpretation of Payam's $t_{\rm h}$?  %  \begin{itemize}  \item The two $t_{\rm h}$s are measuring different things. Payam's $t_{\rm h}$ is considering the {\it diffusion }of a particle's momentum: momentum, or the vorticity of the fluid; or  the characteristic time in the velocity autocorrelation. autocorrelation of neighbouring particles.  My $t_{\rm h}$ is about information flow via sonic waves: this is much smaller than the vorticity time-scale.\\ I want to think about {\it which time scale is more appropriate in this context and why?}  \item So, {\it what should the time-scale be from }physical {\it reasoning: what is the physics behind establishing the flow profile $\vec{v}(\vec{x})$ in the fluid around the DNA/jet?}\\