Oral title: Envelope kinematics of First Core Candidates at 1000 AU scales

Oral abstract: We use multi-lines observations towards the first cores candidates L1451-mm and Per-bol 58, probing their 
envelope kinematics and evolutionary state.  L1451-mm lines, which show infall and rotation, gave us estimates for the infall 
rate and central source mass that further support L1451-mm as the most promising first core candidate. Per-bol 58 spectra 
show two velocity components which can be explained by simulations of a collapsing core, likely just past protostar 
formation, in which infall is regulated by a combination of turbulence and magnetic fields.