def _improve_latex(s):
    """Improve an OSIRIS-generated latex string using common rules."""
    s2 = s.replace('\\omega_p', '\\omega_{\\mathrm{p}}')
    s2 = s2.replace('m_e', 'm_{\\mathrm{e}}')
    s2 = s2.replace('a.u.', '\\mathrm{a.u.}')
    return s2
