Renal macrostructural and hilar Doppler hemodynamic stability during a 7-day head-down tilt bed rest: an exploratory ultrasound-based study in humans under simulated microgravity - Fengxia Yu; Xia Ma; Yawen Liu; Rui Wang; Yiwen Wang; Peng-Gang Qiao; Wei Zheng; Xiangdong Hu; Linxue Qian; Pengling Ren; Zhenchang Wang (Life Sciences in Space Research, 2026)