[Organism as a functional unity of oscillation processes of varying frequency].

The present concept of organism as an oscillating system is discussed in light of the biological rhythms theory. The phenomenon of biological rhythm is viewed as a result of unity and mutual confrontation of the fundamental conflicts in the life process - destruction and creation. Consideration is given to the system-making role of diurnal rhythms keeping the organism functioning as integration.

[Heart rate and energy expenditure during extravehicular activity in different time of day].

The article discusses the comparative heart rate (HR) characteristics associated with day and night extravehicular activities (EVA). HR was commonly higher in the night but not in the daytime. Presumably, the reason is psychological and physiological challenges of the night work on the background of natural performance decrement.

[Topics of cosmonauts' work and rest management on board the International Space Station].

Intensity of the rest and work cycle (WRC) of the ISS cosmonauts was examined in terms of overplanning, as well as frequency of sleep shifting and incidence of crew overstrain evidenced from the weekly reports of MCC-M medical operators. Level of WRC intensity in the recent ISS missions was compared with the WRC chronicles of early missions made by three crewmembers including one cosmonaut, and subsequent missions by six crewmembers including 2 or 3 cosmonauts. Though weak, a trend toward a WRC reduction in the period of 2010-2011 was achieved through a more realistic task planning for an average cosmonaut.

[Stress effects of 72-hour sleep deprivation].

Stress effects of 3-d (72-hr) continuous vigilance were studied for renal excretion of 17-oxycorticoids (17-KS), electrolytes (potassium and sodium), and liquid. The investigation involved 12 male subjects aged 23 to 36. Baseline parameters displayed diurnal variations with comparatively high day and comparatively low night values.

[Dynamics of operator's efficiency under the condition of long continuous vigil].

Chambered male test-subjects (n = 8) kept awake over 72 hours. Every one or two hours during the initial 67 hours they did a tracking test that took 10 to 15 minutes. The test required intense tracking of rhythmic light spots with unpredictably varying frequency and pressing the button as the frequency changed.