Water loss from M-dwarf planets during pre-main sequence evolution

Luger & Barnes "Extreme Water Loss and Abiotic O₂ Buildup On Planets Throughout the Habitable Zones of M Dwarfs"
http://arxiv.org/abs/1411.7412

M dwarfs spend a long time in the pre-main sequence phase, during which time they are substantially more luminous than during the main sequence. This indicates that planets within the habitable zones of M dwarfs spend long periods of time in a runaway greenhouse stage, during which time they can lose large quantities of water and build up abiotic oxygen atmospheres.

Depending on the efficiency at which oxygen is removed from the atmosphere, large quantities of oxygen may remain in the planet's atmosphere, so finding such conditions on a world orbiting an M-dwarf may indicate a desiccated, post-runaway state and thus be an anti-biosignature.

Another one that comes to similar conclusions.

Ramirez & Kaltenegger "The Habitable Zones of Pre-Main-Sequence Stars"
http://arxiv.org/abs/1412.1764

Also consistent with Venus losing its water during its accretion.