2013a-395 adaptation astronautics astrophysics cardiovascularphysiologicalphenomena cardiovascularsystem clinicalmedicine congresses diseases earthsciences effectofreducedgravityon effectofspaceflighton erythrocytes evidence-basedmedicine exobiology fitness fluids general gravity health heliosphere(astrophysics) hypergravity hypogravity internalmedicine matter medical oxygenconsumption physicalsciences physiological physiologicaleffect physiology qp research spacemedicine unitedstates weightlessness wg102