Testing Larson's relationships in massive clumps
  We tested the validity of the three Larson relations in a sample of 213
massive clumps selected from the Herschel Hi-GAL survey and combined with data
from the MALT90 survey of 3mm emission lines. The clumps have been divided in 5
evolutionary stages to discuss the Larson relations also as function of
evolution. We show that this ensemble does not follow the three Larson
relations, regardless of clump evolutionary phase. A consequence of this
breakdown is that the virial parameter $\alpha_{vir}$ dependence with mass (and
radius) is only a function of the gravitational energy, independent of the
kinetic energy of the system, and $\alpha_{vir}$ is not a good descriptor of
clump dynamics. Our results suggest that clumps with clear signatures of infall
motions are statistically indistinguishable from clumps with no such
signatures. The observed non-thermal motions are not necessarily ascribed to
turbulence acting to sustain the gravity, but they may be due to the
gravitational collapse at the clump scales. This seems particularly true for
the most massive (M$\geq$1000 M$_{\odot}$) clumps in the sample, where also
exceptionally high magnetic fields may not be enough to stabilize the collapse.
