Fig.~\ref{r_sigma} shows luminous mass as a function of radius, $R$, for each GMA, with the expected fit line as found in \citet{Solomon_1987} for GMCs in the Milky Way galaxy:

\begin{equation}
M_{\mathrm{lum}} = 540R^2 (M_{\odot}).
\label{eqn1}
\end{equation}

The nuclear GMAs are more massive for their sizes compared to equivalently sized disk clouds. While the inter-arm GMAs are less massive than similarly sized arm GMAs.
