Exploring the Variability of the Flat Spectrum Radio Source 1633+382.
  II: Physical Properties
  The flat spectrum radio quasar 1633+382 (4C~38.41) showed a significant
increase of its radio flux density during the period 2012 March - 2015 August
which correlates with gamma-ray flaring activity. Multi-frequency simultaneous
VLBI observations were conducted as part of the interferometric monitoring of
gamma-ray bright active galactic nuclei (iMOGABA) program and supplemented with
additional radio monitoring observations with the OVRO 40m telescope, the
Boston University VLBI program, and the Submillimeter Array. The epochs of the
maxima for the two largest gamma-ray flares coincide with the ejection of two
respective new VLBI components. Analysis of the spectral energy distribution
indicates a higher turnover frequency after the flaring events. The evolution
of the flare in the turnover frequency - turnover flux density plane probes the
adiabatic losses in agreement with the shock-in-jet model. Derived synchrotron
self absorption magnetic fields, of the order of 0.1mG, do not seem to
dramatically change during the flares, and are much smaller, by a factor
$10^4$, than the estimated equipartition magnetic fields, indicating that the
source of the flare may be associated with a particle dominated emitting
region.
