\newcommand{\CGrowTime}{
\Delta \log       \mathbf{C} _{t+1} & = & \varsigma + \chi
\Delta \mathbf{E}[\log       \mathbf{C}_{t} ]
 + \eta \mathbf{E}[\Delta \log       \mathbf{Y} _{t+1}] +
{\alpha} \mathbf{E}[{     A }_{t}]
}
\newcommand{\CMeasGrowTime}{
\Delta \log       \underbrace{\tilde{\mathbf{C}} _{t+1}}_{=\epsilon_{t+1}\mathbf{C}_{t+1}} & = & \varsigma + \tilde{\chi }
\Delta \mathbf{E}[\log \tilde{  \mathbf{C}}_{t} ]
 + \eta \mathbf{E}[\Delta \log  \bar{     \mathbf{Y} }_{t+1}] +
{\alpha} \mathbf{E}[{ \bar{    A }}_{t}]
}
