Relationship between the size, Hα luminosity (no reddening corrected), and velocity dispersion of the clumps of star formation. This figure is similar to that presented by Wisnioski et al. (2012), but here we focus on the comparison between the U/LIRGs clumps (blue) and those for high-z samples (red). The present values correspond to those of the narrow component in a two-Gaussian fit (see text). Note that we have homogenized luminosity and size measurements among the different studies. For the works by Genzel et al. (2011) and Wisnioski et al. (2012), the Hα luminosity correspond to the total value after removing the contribution of the broad component with a mean global value of 40 percent (Wisnioski et al.), and the individual values reported by Genzel et al.. We have only considered individual clumps from Genzel et al. (2011). For Monreal-Ibero et al. (2007) and Genzel et al. (2001) the observed (i.e., non-reddening corrected) luminosities were calculated from the observed fluxes. In order to homogenize the different methods for inferring sizes, in this plot we have transformed the present half-light measurements given in Table B.1 (and those by Monreal-Ibero et al. 2007) into core measurements as those considered by Wisnioski et al. and Genzel et al., following the results by Forster-Schreiber et al. (2009), according to which 0.5 × FWHM/r_hl ~ 1.45. The clump in IRAS 06206 is not included, as only an upper limit on its size was derived. The dash lines correspond to the mean behaviour (i.e., least-squares best fit) reported by Wisnioski et al. using a large compilation of local and high-z data, and statistically dominated by the local HII regions and giant HII regions.