\begin{table}%t6 %\centering \par \caption {\label{table:dustgas2}Power-law relations and correlation coefficients $r_{\rm c}$ between the emission from dust and ionized gas. } \begin{tabular}{ l l l l l l l l} \hline\hline \noalign{\smallskip} $X$ & $Y$ & $R$ & ~~~~~~ $a_{\rm c}$ & ~~~~~~$b$ & $n$ & ~~~~~~ $r_{\rm c}$ & $t$\\ ($10^{-7}$ erg~s$^{-1}$~cm$^{-2}$~sr$^{-1}$) & (MJy/sr) & ($\arcmin$)& & & & &\\ \hline $I_{{\rm H}\alpha}$ &$I_{24~\mu{\rm m}}$ & 0--30 & --1.76~$\pm$~0.05 & 0.94~$\pm$~0.03 & 417 & 0.79~$\pm$~0.03 & 27\\ & & 30--50 & --1.75~$\pm$~0.05 & 1.00~$\pm$~0.03 & 677 & 0.75~$\pm$~0.03 & 30\\ & & 0--50 & --1.75~$\pm$~0.05 &0.98~$\pm$~0.02 & 1094 & 0.76~$\pm$~0.02 & 38\\ & & & & & & &\\ $I_{{\rm H}\alpha}$ & $I_{70\mu{\rm m}}$ & 0-30 & --1.04~$\pm$~0.03 & 1.10~$\pm$~0.03 & 412 & 0.83~$\pm$~0.03 & 30\\ & & 30--50 &--0.96~$\pm$~0.03 &1.09~$\pm$~0.03 & 677 & 0.78~$\pm$~0.02 & 32 \\ & & 0--50 &--0.98~$\pm$~0.02 &1.09~$\pm$~0.02 & 1089 & 0.79~$\pm$~0.02 & 43 \\ & & & & & & &\\ $I_{{\rm H}\alpha}$& $I_{160\mu{\rm m}}$ & 0-30 & 0.26~$\pm$~0.05 & 0.76~$\pm$~0.03 & 417 & 0.54~$\pm$~0.04 & 13\\ & & 30--50 &0.47~$\pm$~0.04 &0.72~$\pm$~0.02 & 678 & 0.73~$\pm$~0.03 & 28 \\ \hline \end{tabular} \tablefoot {Ordinary least-squares fits of bisector log~($Y$)~=~$a_{\rm c}+b$~log~($X$) through $n$ pairs of (log~$X$, log~$Y$), where $n$ is the number of independent points (Isobe et~al. 1990); $t$ is the student-t test.} \end{table}