Anomalous peculiar motions of high-mass young stars in the Scutum spiral
  arm
  We present trigonometric parallax and proper motion measurements toward 22
GHz water and 6.7 GHz methanol masers in 16 high-mass star-forming regions.
These sources are all located in the Scutum spiral arm of the Milky Way. The
observations were conducted as part of the Bar and Spiral Structure Legacy
(BeSSeL) survey. A combination of 14 sources from a forthcoming study and 14
sources from the literature, we now have a sample of 44 sources in the Scutum
spiral arm, covering a Galactic longitude range from 0$^\circ$ to 33$^\circ$. A
group of 16 sources shows large peculiar motions of which 13 are oriented
toward the inner Galaxy. A likely explanation for these high peculiar motions
is the combined gravitational potential of the spiral arm and the Galactic bar.
