  We have carried out the Gaussian model-fitting to the 15 GHz VLBA cores for a
sample of blazars from the MOJAVE database, analyzed the correlations in the
model-fitted parameters and studied the variability properties for different
group of sources. We find that the Fermi LAT-detected blazars have on average
higher position angle changes of cores than the LAT non-detected blazars, and
that the LAT-detected ones largely associate with more variable cores in flux
density.
