Remember that the estimates of \sigma are on the log scale, so negatives imply a standard deviation smaller than 1. E.g. the standard deviation for USA in 1994 might be something like \sigma_\texttt{USA,1994}=\exp(s_\texttt{USA} + s_\texttt{1994})=\exp(0.2-0.4)=\exp(-0.2)\approx 0.82.
Ps: just out of the blue… Are you working with FDI data?