\begin{table}%t2
\caption{\label{param}Models parameters.}  
%\centerline
{\small
\begin{tabular}{ccccc} 
  \hline\hline 
\noalign{\smallskip} 
Model &  $\tau$ & $\nu$ & Thres. & Line \\ 
& Gyr & Gyr$^{-1}$ & $M_{\odot}~$pc$^{-2}$ & type \\ 
\noalign{\smallskip} 
  \hline 
\noalign{\smallskip} 
MW-A1 & $0.75R+1.08$ & 1.0 & 7 & solid  \\ 
% &  &  \\ 
MW-A2 & $0.75R+1.08$ & 1.0 & 4 & dots \\ 
MW-B & $0.75R+1.08$ & $11/R-0.4$ & 4 & dashed \\ 
% &  &  \\ 
M~31-A1 & $0.62R+1.62$ & 1.0 & 5 & solid \\ 
% &  &  \\ 
M~31-A2 & $0.62R+1.62$ & 2.0 & 5 & dots\\ 
% &  &  \\  
M~31-B & $0.62R+1.62$ & $24/R-1.5$ & 5 & dashed \\ 
 M~31-Bk1.25* &  $0.62R+1.62$ & $24/R-1.5$ & 5 & dot-dashed \\
M~33-A05 & $0.85R+4.54$ & 0.5 & 2 & solid \\ 
M~33-A01 & $0.85R+4.54$ & 0.1 & 2 & dots \\ 
M~33-B & $0.85R+4.54$ & 1/R & 2 & dashed \\ 
\hline 
\end{tabular}} 
\tablefoot{*~For M~31, we tested a model with a different exponent for the gas density in the SFR ($k=1.25$), using the lower value proposed by Kennicutt (\cite{Kennicutt1998}) $1.4 \pm 0.15$.}
\end{table}