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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Densitography - A new method for evaluation of cardiac performance of rest and during exercise.

The validity of the densitographic curves obtained from the pinna of the ear for measuring the systolic intervals has been investigated in 28 subjects. This technique is found to permit the performance of noninvasive physiologic studies during physical activities, exercise tests, flight conditions, and probably long-term monitoring of critically ill patients. Densitographic curves constitute an excellent substitute by which to measure time-base intervals of the cardiac cycle when the carotid pulse tracing is not available.

Chirife, R.↗
NASA NTRS1972

Skin and muscle components of forearm blood flow in directly heated resting man.

Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

Detry, J.-M. R.↗
NASA NTRS1972

+Gz tolerance after 14 days bed rest and the effects of rehydration.

Measurement of the reduction in centrifugation tolerance after two weeks of bedrest with moderate daily exercise, with an attempt to determine if rehydration improves +Gz tolerance. There were significant reductions in +Gz tolerance during bedrest periods at three acceleration levels. Rehydration resulted in a significant increase in tolerance at 2.1G but it did not restore tolerance to control levels. Rehydration did not affect tolerance at 3.2G and 3.8G.

Greenleaf, J. E.↗
NASA NTRS1972

An upper limit on the neutrino rest mass.

It is pointed out that the measurement of the deceleration parameter by Sandage (1972) implies an upper limit of a few tens of electron volts on the sum of the masses of all the possible light, stable particles that interact only weakly. In the discussion of the problem, it is assumed that the universe is expanding from an initially hot and condensed state as envisaged in the 'big-bang' theories.

Cowsik, R.↗
NASA NTRS1975

Structural and cytochemical investigations of the gravity receptor under conditions of relative rest and following exposure to accelerations

When investigating the influence of g-forces on vertebrates, a number of cytochemical and ultrastructural changes are observed: deflection of the stereocilia, change in concentration as well as the localization of a number of chemical biologically active substances, displacement of the mitochondria, their pressure against the membranes, the release into the cytoplasm of the ribosomes of nucleolar RNA, the formation of additional membranes in the cytoplasmatic network, etc. According to preliminary data, it is assumed that similar processes are observed in the gravity receptors of invertebrates as well. It is concluded that gravity receptors in vertebrates and invertebrates are strikingly similar despite different evolutionary paths.

Aronova, M. Z.↗
NASA NTRS1977

Vectorcardiographic changes during extended space flight (M093): Observations at rest and during exercise

The objectives of Skylab Experiment M093 were to measure electrocardiographic signals during space flight, to elucidate the electrophysiological basis for the changes observed, and to assess the effect of the change on the human cardiovascular system. Vectorcardiographic methods were used to quantitate changes, standardize data collection, and to facilitate reduction and statistical analysis of data. Since the Skylab missions provided a unique opportunity to study the effects of prolonged weightlessness on human subjects, an effort was made to construct a data base that contained measurements taken with precision and in adequate number to enable conclusions to be made with a high degree of confidence. Standardized exercise loads were incorporated into the experiment protocol to increase the sensitivity of the electrocardiogram for effects of deconditioning and to detect susceptability for arrhythmias.

Smith, R. F.↗
NASA NTRS1976

Body composition changes in men and women after 2-3 weeks of bed rest

Several parameters of body composition were measured in eight men before and after 14 days of continuous recumbency, and in eight women before and after 17 days of recumbency. The parameters measured included body weight, body water, body potassium, plasma volume, and plasma protein concentrations. From these, values were derived for body fat content, lean body mass, body mass, and circulating plasma proteins. In general, the men and women responded similarly to continuous recumbency. Characteristically, there was significant reduction of plasma volume and body potassium in both groups. The women showed a significant reduction in circulating plasma protein, entirely in the albumin fraction; a similar change was observed in the men. The women, but not the men, showed a significant increase in circulating fibrinogen. Both men and women lost body cell mass, while body fat content remained the same or tended to increase slightly. It is expected that similar changes would occur in weightlessness. It is further concluded that women should tolerate the weightlessness of space flight physiologically as well as men.

Pace, N.↗
NASA NTRS1978

Development of an hypothesis for simulating anti-orthostatic bed rest

The Guyton model, modified by the addition of leg compartments and the effect of the gravity vector, was used to evaluate hypotheses describing leg dehydration and fluid shifts. While the study is not complete, the basic approach was shown to be useful by identifying important mechanisms, identifying systems which need further experimental description and by assisting in the development of a general hypothesis.

Leonard, J. I.↗