A dynamically young and perturbed Milky Way disk.

The evolution of the Milky Way disk, which contains most of the stars in the Galaxy, is affected by several phenomena. For example, the bar and the spiral arms of the Milky Way induce radial migration of stars and can trap or scatter stars close to orbital resonances. External perturbations from satellite galaxies can also have a role, causing dynamical heating of the Galaxy, ring-like structures in the disk and correlations between different components of the stellar velocity.

Cardio-respiratory changes during the onset of head-down tilt.

Background: During spaceflight, changes in the cardiovascular system and in pulmonary mechanics take place but no apparent impairment of respiratory function occurs. However, little is known about the first hours in microgravity.

Hypothesis: The changes occurring at the same time in the cardiovascular and pulmonary systems could interact and lead to a transient impairment of blood gases at the onset of microgravity.