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\begin{equation}
  S(r)=S_{0,1}(1+\frac{r^2}{r_{c,1}^2})^{-3\beta_1+1/2}+S_{0,2}(1+\frac{r^2}{r_{c,2}^2})^{-3\beta_2+1/2}\notag
\end{equation}
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