\item Curvature of the band:\\
$\frac{d^2E}{dk^2}=\frac{d^2}{dk^2}\frac{\hbar^2k^2}{2m_{eff}}
=\frac{\hbar^2}{m_{eff}}$
- \item
+ \item \begin{minipage}{0.5\textwidth}
+ $m_n=m_p$:\\
+ \includegraphics[width=5cm,angle=-90]{dos_is_1.eps}
+ \includegraphics[width=5cm,angle=-90]{fermi_1.eps}
+ \includegraphics[width=5cm,angle=-90]{ccc_1.eps}
+ \end{minipage}
+ \begin{minipage}{0.5\textwidth}
+ $m_n \ne m_p$:\\
+ \includegraphics[width=5cm,angle=-90]{dos_is_2.eps}
+ \includegraphics[width=5cm,angle=-90]{fermi_2.eps}
+ \includegraphics[width=5cm,angle=-90]{ccc_2.eps}
+ \end{minipage}
\end{enumerate}
\section{'Density of state mass' of holes in silicon}