\renewcommand{\rmdefault}{ptm}
%
% make sure that all versions of pdftex can process more than 512 inclusions
%
\let\normalpdfximage\pdfximage\def\pdfximage{\immediate\normalpdfximage}

\def\headrulewidth{0pt}
\setcounter{tocdepth}{3}
%\twocolumn
\columnseprule 0pt      %    Width of rule between columns.

\makeatletter
\def\subsection{\@startsection{subsection}{2}{\z@}{2.6ex plus .8ex minus
   .17ex}{1.2ex plus .17ex}{\large\it}}
\def\section{\secdef\@sectionb\@sections}
\def\@sectionb[#1]#2{\@sections{#2}}
\def\@sections#1{\@startsection {section}{1}{\z@}
                {2.8ex plus 0.8ex minus .1ex}{1.5ex plus .2ex}
                {\large\bf\boldmath\centering}{\uppercase{#1}}}
\def\abstract{\subsection*{Abstract}}
\def\endabstract{\par}
\def\maketitle{\par
 \begingroup
   \twocolumn[\@maketitle]
 \endgroup
 \let\maketitle\relax
 \let\@maketitle\relax
 \gdef\@author{}\gdef\@title{}}

\newlength{\titleblockheight}       % so user can change it if need be
\setlength{\titleblockheight}{50mm}

\def\@maketitle{\vbox to \titleblockheight {\hsize\textwidth
  \linewidth\hsize \vskip 3pt \centering
  {\Large\bf \@title \par}
  \vskip 2em                % Vertical space after title.
  {\large\begin{tabular}[t]{@{}c@{}}\@author \end{tabular}\par}
  \vfil}}
\makeatother

\newcommand\high[1]{\ensuremath{^{#1}}}
\newcommand\low[1]{\ensuremath{_{#1}}}
