deletions | additions       diff --git a/subsectionInfall_Fou.tex b/subsectionInfall_Fou.tex  index b093680..30cc9a0 100644  --- a/subsectionInfall_Fou.tex  +++ b/subsectionInfall_Fou.tex 
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\subsection{Infall}  Four sources, N62-1, N65-2, N90-2 and N117-3, have a non-Gaussian line profile (see Fig. \ref{infall}). profile.  In three cases the line profile is stronger on the blue-side. The line-profile of blue-side {\bf (see Fig. \ref{infall})}. {\bf Of these three sources,  N117-3 is double-peaked with the blue-shifted peak stronger than has {\bf  the strongest  red-shifted peak. emission, with two clear peaks present}.  The line-profiles of N62-1 and N90-2 are single-peaked but with a plateau on the red-shifted side. We interpret these three profiles as evidence of infall. N62-1 and N90-2 both are located in infrared dark clouds that intersect their nearby bubble (N62 and N90). Thus, infall, if present, could be triggered by an expanding HII region via radiatively driven implosion or collect-and-collapse. N117-3 is located within in the bubble, in projection. There is no obvious interpretation for this infall candidate's interaction with the associated bubble N117. \citet{Myers1996} and \citet{Williams1999} present a model of infall that predicts line profiles similar to these observations. They assume two clouds (near and far) falling toward a common center and estimate the resulting line profiles accounting for optical depth effects as well as standard radial-dependencies of velocity and excitation temperature. \citet{Myers1996} show that an optically thick line and a higher excitation temperature on the cloud on the fars side can produce a blue-shifted weighted line-shape. With further simplifications they show that by measuring five parameters, the Myers et al. (1996) model allows an estimate of the infall velocity. The measured parameters are: $\sigma$ (velocity dispersion of an optically thin tracer), T$_{BD}$ (the blue-shifted excess emission), T$_{RD}$ (the red-shifted emission), T$_D$ (the plateau emission), v$_{red}$ (the red-shifted peak emission velocity) and v$_{blue}$ (the blue-shifted peak emission velocity). See Figure 2 in \citet{Myers1996} for a diagram of these different quantities. When all quantities can be measured, the infall velocity is estimated to be: