The Scaling Relations of Local and High-Redshift Star-Forming Regions {#sec:scaling}
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The internal kinematics and luminosities of H[ii]{} regions in local galaxies, derived from the line widths of their emission lines, have been the subject of various studies for some time [e.g. @Terlevich81; @Arsenault90; @Rozas98; @Rozas06; @Relano05]. In particular, if the large line widths of star-forming H[ii]{} regions reflect the virialization of the gas then they can be used to determine their masses. However, it is unlikely that this condition holds exactly at any time during the evolution of a H[ii]{} region due to the input of radiative and mechanical energy, principally from their ionizing stars [e.g.  @Castor75]. Nonetheless, the least evolved H[ii]{} regions may well be within a factor of a few (2–3) of having their kinematics determined by their virial masses (at an early stage, the stellar ionizing luminosities are maximized whereas the mechanical energy input is minimized; @Leitherer99). In the case of H[ii]{} regions close to virial equilibrium, the use of the line-width to compute gaseous masses offers a relatively direct means to study the properties since it is independent of the small-scale structure (density, filling factor, etc.).

@Terlevich81 showed that the H$\beta$ luminosity of the most 