Spiral structure parameters in the solar neighbourhood
  Two samples of O- and B-type stars and Cepheids with Hipparcos data have been used to characterize galactic rotation and spiral arm kinematics in the solar neighbourhood. An extensive set of simulations has been performed in order to assess the capabilities of the method and its sensitivity to sample errors and biases in the adopted parameters. 
D. Fernandez, X. Luri, F. Figueras, J. Torra