I got two hours of sleep a day, which is not enough, although four hours would be sufficient. In order to get more sleep this time I'm going to try to reduce the amount of air-traffic control communication that I have to do, so that I'm not constantly on the radio. NOVA: Your last flight lasted a little over six days.
Alpha and beta glucose differ in stereochemistry at one single carbon. In the alpha-form, a bulky group is in a so-called axial position, and in the beta-form, the group is in a more favourable equatorial position. These different positions lead to different bonds in polysaccharides, giving rise to a need for different enzymes to digest them.
When the glucose level is high, the beta cells secrete insulin into the blood; when glucose levels are low, secretion of insulin is inhibited. Their neighboring alpha cells, by taking their cues from the beta cells, secrete glucagon into the blood in the opposite manner: increased secretion when blood glucose is low, and decreased secretion when glucose concentrations are high.