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Biomedical subjects

S I Stepanova

Publications and source records attributed to S I Stepanova.

25 records · Page 2Linked to original sources
PubMedDate not supplied

[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. Time of latent reaction was determined. The variable was shown to extend with the confinement and fluctuate with the period of approx. 28 hours. Average values on the first sleepless night was longer than the ones on the previous day in all subjects with personal difference ranging from 7 to 37% and averaging 21%. That is, on the first night everyone was less efficient as compared with the previous day which could be excused by fatigue and natural variations in mental efficiency known to rise in the day and reduce in the night hours.

Adult↗
PubMedDate not supplied

[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. During the 72-hr vigilance, significant and consistent (statistically fiducial) intensification of 17-KS and potassium excretion occurred in the night-time, i.e., in the period of naturally low values, but only in the first two sleepless nights. As for sodium and liquid excretion, stress-related reduction in these parameters was more consistent and distinct in the day-time, i.e., in the period of naturally high values, rather than in the nighttime. Therefore, the two factors that should be accounted for by investigators of continuous vigilance (and, maybe, other stresses) are the anticipated direction of a stress-reaction and baseline diurnal variation of parameters under study. If stress is expected to increase a parameter, measurements should be done when the parameter is naturally low and, vice versa, if stress is known to reduce a parameter, then measurement should be planned in the period when it is naturally high. If direction of stress-related changes is predictable, investigations can be performed on a twenty-four hour basis.

17-Ketosteroids↗
PubMedDate not supplied

[Stress and biological rhythms].

Numerous data give evidence that the reactions of the human body to diverse stimuli vary in an oscillatory, wave-like pattern. This phenomenon is associated with a general biological law of the wave-like pattern of adaptive processes, according to which they are realized at any stage (anxiety, resistance, depletion) in an oscillatory pattern. The wave-like pattern of the adaptive process is an expression of the dialectic law of unity and struggle of opposites; in this case, unity and struggle of construction and destruction, maintaining continuous self-reproduction and self-preservation of a living system in its environment. In order to improve the methods and procedures for sustaining man-in-space, further studies are required to investigate specific manifestations of this law.

Adaptation, Physiological↗
PubMedDate not supplied

[Biorhythm status as 1 of the selection criteria for cosmonauts].

The concept of biorhythmological status of the human body understands it as a sum total of biorhythmological characteristics of the organism. The status is discussed in two aspects: constancy and variability of circadian rhythns of vital functions. The relationship between the two parameters is described in the light of a hierarchic structure of the circadian system. The dependence of stress-resistance upon integrity and level of organization of the circadian system is ascertained. The importance of assessment of biorhythmological status for proper cosmonaut selection is emphasized.

Adaptation, Physiological↗