uniform notation of cross section with d, not \partial.

Doc/UserManual/Instrument.tex

@@ -277,14 +277,14 @@ Altogether,
 the expected count rate in detector pixel $(i,j)$ is proportional to
 \begin{equation}\label{EItrafo_cos}
   I_{ij} = \cos^3\!\alpha_\sf\, \cos^3\!\phi_\sf\:
-          \frac{\partial\sigma}{\partial\Omega}(\q_{ij}),
+          \frac{\d\sigma}{\d\Omega}(\q_{ij}),
 \end{equation}
 where we have omitted constant factors $L^{-2}$, $\Delta y$ and $\Delta z$.
 Using pixel coordinates instead of angles, this can be rewritten as
 \Emph{%
 \begin{equation}\label{EItrafo_pix}
   I_{ij} = \left( 1+\frac{y^2+z^2}{L^2}\right)^{-3/2}
-          \frac{\partial\sigma}{\partial\Omega}\bigl(\q_{ij}(y,z)\bigr).
+          \frac{\d\sigma}{\d\Omega}\bigl(\q_{ij}(y,z)\bigr).
 \end{equation}
 \vspace*{-2pt}}
 %(usually as the centre between the transmitted