نتایج جستجو برای: weightlessness
تعداد نتایج: 445 فیلتر نتایج به سال:
Background: spacecrafts rotate around the Earth every 90 minutes, so the 24-hour cycle turns to 90 minutes. Retinoic acid, an active metabolite of vitamin A, plays a role in regulating the circadian rhythm and its deficiency can impair the biological clock function and consequently impair the circadian rhythm of locomotor activity. The goal of the study was to assay the effects of simulated spa...
An object in outer space is weightless due to the absence of gravity, but astronauts can still judge whether one object is heavier than another one by accelerating the object. How heavy an object feels depends on the exploration mode: an object is perceived as heavier when holding it against the pull of gravity than when accelerating it. At the same time, perceiving an object's size influences ...
Weight-bearing bone is constantly adapting its structure and function to mechanical environments. Loading through routine exercises stimulates bone formation and prevents bone loss, but unloading through bed rest and cast immobilization as well as exposure to weightlessness during spaceflight reduces its mass and strength. In order to elucidate the mechanism underlying unloading-driven bone ada...
The principal objective of the research reported here was to determine whether a plant's periodic growth oscillations, called circumnutations, would persist in the absence of a significant gravitational or inertial force. The definitive experiment was made possible by access to the condition of protracted near weightlessness in an earth satellite. The experiment, performed during the first fl...
Many astronauts after being weightless in space become hypotensive and presyncopal when they assume an upright position. This phenomenon, known as orthostatic intolerance, may interfere with astronaut function during reentry and after spaceflight and may limit the ability of an astronaut to exit a landed spacecraft unaided during an emergency. Orthostatic intolerance is more pronounced after lo...
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