Answer:
Free fall.
Explanation:
When astronauts sleep in space, they sleep in small cabins or in sleeping bags that are attached to the wall or ceiling of the station. Everything is weightless as there’s no gravity in space. So while sleeping there is a chance of floating around and bumping into things. Astronauts use sleeping bags that can be tethered to the wall or ceiling to solve this problem. Also the tethered sleeping bags provide a normal sleeping environment to the astronauts as they can feel pressure on their back and head. Their sleeping cabin is well ventilated as they can wake up with breathing trouble as a result of the inhalation of their own exhaled carbon dioxide which formed around their heads as a bubble. They use earplugs and a sleep mask to block the noise and light and can sleep vertically or horizontally. Compared to earth, sleeping is a bit different in space.
Water is a key element and necessary thing life needs in order to live and thrive without water everything would die.
When
the morning announcements call for you to rise to recite the pledge of
allegiance, the signal to stand up on your feet is sent by the somatic nervous system. The somatic nervous system is <span>part of the peripheral nervous system. Its functions are : </span><span>voluntary movement of the muscles and organs and reflex movements. So, the signal to stand up on our feet in the morning is movement of the organs sent by this system. </span>
Designing efficacious norovirus vaccines remains a major challenge due to several factors:
(1) the extreme genetic variability within the norovirus family and within genogroups
(2) the rapid evolution of antigenically dissimilar pandemic GII.4 norovirus strains
(3) the lack of lasting immunity upon natural exposure to noroviruses in at least a proportion of the population.
