INTRODUCTION Orthostatic hypotension is a serious risk for crewmembers returning from spaceflight. Numerous cardiovascular mechanisms have been proposed to account for this problem, including vascular and cardiac dysfunction, which we studied during bed rest. METHODS Thirteen subjects were studied before and during bed rest. Statistical analysis was limited to the first 49-60 d of bed rest an...

rade control structures are used to control bed erosion in steep small rivers mostly in the mountains. Scour downstream of this structure can lead to failure. Over the past years, the effect of different variables on this phenomena have been studied, however the effect of upward seepage which is common due to head difference of the banks water table or water surface level between the upstream a...

the effect of chair position on respiratory parameters in patients undergoing mechanical ventilation     fallahinia ghh [1] ,baghcheghi n [2] ,oshvandi kh [3] *,taher a [4] , soltanian ar [5]     received: 7 feb, 2013 accepted: 15 may, 2013    abstract  background & aims : there are many barriers to the movement of patients requiring mechanical ventilation and these patients are at risk for com...

Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that...

We determined the effects of prolonged head-down tilt bed rest (HDT) on lung mechanics and gas exchange. Six subjects were studied in supine and upright postures before (control), during [day 113 (D113)], and after (R + number of days of recovery) 120 days of HDT. Peak expiratory flow (PF) never differed between positions at any time and never differed from controls. Maximal midexpiratory flow ...