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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 253 records · Page 14

All sources NASA NTRS DOE OSTI

NASA NTRS1972

Circadian rhythm asynchrony in man during hypokinesis.

Posture and exercise were investigated as synchronizers of certain physiologic rhythms in eight healthy male subjects in a defined environment. Four subjects exercised during bed rest. Body temperature (BT), heart rate, plasma thyroid hormone, and plasma steroid data were obtained from the subjects for a 6-day ambulatory equilibration period before bed rest, 56 days of bed rest, and a 10-day recovery period after bed rest. The results indicate that the mechanism regulating the circadian rhythmicity of the cardiovascular system is rigorously controlled and independent of the endocrine system, while the BT rhythm is more closely aligned to the endocrine system.

Winget, C. M.↗

NASA NTRS1974

Compact telemetry package for remote monitoring of neutron responses in animals

Battery-powered telemeter includes FM transmitter and is light enough to be mounted on animal's head. Animal has complete freedom of movement while its neuron responses are transmitted to receiver in laboratory. Construction may also be applied to monitor blood pressure, body temperature, and different muscular signals.

Baker, C. D.↗

NASA NTRS1974

Heart-rate pulse-shift detector

Detector circuit accurately separates and counts phase-shift pulses over wide range of basic pulse-rate frequency, and also provides reasonable representation of full repetitive EKG waveform. Single telemeter implanted in small animal monitors not only body temperature but also animal movement and heart rate.

Anderson, M.↗

NASA NTRS1974

Circadian, endocrine, and metabolic effects of prolonged bedrest: Two 56-day bedrest studies

Two bedrest studies of 56 days each have been conducted to evaluate the effects of prolonged bedrest on circadian synchrony and endocrine and metabolic function. Measurements included the pituitary-adrenal, thyroid, parathyroid, insulin-glucose-growth hormones, catecholamine excretion, body temperature, and heart rate. The results indicated that a rigorous regimen of exercise did not prevent the endocrine and metabolic effects of prolonged bedrest. Changes in circadian, endocrine, and metabolic functions in bedrest appear to be due to changes in hydrostatic pressure and lack of postural cues rather than to inactivity, confinement, or the bleeding schedule. Prolonged bedrest, particularly beyond 24 days, resulted in rhythm desynchronization in spite of well regulated light/dark cycles, temperature, humidity, activity, and meal times and meal composition and in increased lability of all endocrine parameter measured. It also resulted in an apparent insensitivity of the glucose response to insulin, of cortisol secretion to ACTH, and of growth hormone secretion to hypoglycemia.

Vernikos-Danellis, J.↗

NASA NTRS1974

Cycles in metabolism and heat loss

Using calorimetric techniques, subjects' metabolism, thermoregulation, and body temperatures were monitored continuously for 24-hour days, using three types of experimental routines. A water cooling garment (WCG) was used for direct calorimetry, while partitional calorimetry was used to establish a non-suited comparison for one of the routines. In this replicated routine, called the quiet day, the subjects were sedentary throughout the daytime hours and slept normally at night. Results indicate that the WCG may act to reduce 24-hour total oxygen consumption (VO2) or heat production, possibly due to the lowered energy cost of thermoregulation.

Annis, J. F.↗

NASA NTRS1973

Effect of skin wettedness on sweat gland response

Investigation of the effect of skin wettedness upon sweating rate. Several techniques were used to gain a better understanding of the quantitative nature of this effect. The results include the finding that the evaporative power of the environment has a profound effect on the relationship between body temperature and sweating rate.

Nadel, E. R.↗

NASA NTRS1974

Analytic model for assessing the thermal performance of scuba divers

A biothermal model with a physically-controlled subsystem and a dynamically-controlled subsystem is developed to simulate the thermoregulatory system of man under immersed conditions. The model is consistent with experimental data for seminude subjects immersed to neck in cool to temperate water and for 'wet-suited' subjects immersed to neck in cold water. Equations are derived for predicting body temperatures under various dive conditions.

Montgomery, L. D.↗

NASA NTRS1975

Recent NASA contributions to biomedical telemetry

The present work reviews technological progress over the past five years in the field of long-term telemetric monitoring of physiological parameters during space flight. Emphasis is placed on those developments that have direct application to animal or human use on earth. An effort was made in these recent developments to free subjects from encumbering wires: a swallowable telemetry capsule for monitoring body temperature and a wristwatch transmitter connected to EKG leads were two of the devices developed.

Sandler, H.↗

NASA NTRS1975

Radio-frequency and microwave energies, magnetic and electric fields

The biological effects of radio frequency, including microwave, radiation are considered. Effects on body temperature, the eye, reproductive systems, internal organs, blood cells, the cardiovascular system, and the central nervous system are included. Generalized effects of electric and magnetic fields are also discussed. Experimentation with animals and clinical studies on humans are cited, and possible mechanisms of the effects observed are suggested.

Michaelson, S. M.↗

NASA NTRS1976

Propranolol and pyrogen effects on shivering and nonshivering thermogenesis in rats

The influence of pyrogen and propranolol (a beta-adrenergic antagonist) on shivering and nonshivering thermogenesis (NST) in male rats exposed to 24-25 C and 17-18 C is studied. It is found that intavenous injection of an exogenous pyrogen into rats exposed to 24-25 C elicited a thermogenic response manifested by elevated body temperature, rate of oxygen consumption, and shivering activity, and that propranolol markedly diminished the pyrogen-induced increases in oxygen consumption and colonic temperature, with little changes in shivering activity. In contrast, in cold-exposed rats, propranolol did nor significantly affect the pyrogen-evoked thermogenesis; shivering rather tended to increase when NST was blocked. It is suggested that the fibrile responses evoked by exogenous pyrogen involve differential effects on the two modes of heat production. The assumption that pyrogen acts at a site common to both shivering and nonshivering pathways or that it uniformly alters the individual set points and/or thresholds for both thermogenic effectors is therefore unlikely in the light of the data presented.

Horwitz, B. A.↗

NASA NTRS1975

Biological rhythms

An overview is given of basic features of biological rhythms. The classification of periodic behavior of physical and psychological characteristics as circadian, circannual, diurnal, and ultradian is discussed, and the notion of relativistic time as it applies in biology is examined. Special attention is given to circadian rhythms which are dependent on the adrenocortical cycle. The need for adequate understanding of circadian variations in the basic physiological indicators of an individual (heart rate, body temperature, systolic and diastolic blood pressure, etc.) to ensure the effectiveness of prophylactic and therapeutic measures is stressed.

Halberg, F.↗

NASA NTRS1977

Skylab hardware report operational bioinstrumentation system

The Skylab Operational Bioinstrumentation System is a personal, individually adjustable biomedical system designed to monitor the basic physiological functions of each suited crewman during specified periods of a manned space mission. The basic physiological functions of this system include electrocardiogram, respiration by impedance pneumogram, body temperature, cardiotachometer, and subject identification. The Operational Bioinstrumentation System was scheduled to monitor each crewman during launch, extravehicular activities, suited intravehicular experiments, and undocking and return.

Luczkowski, S.↗

NASA NTRS1976

Two mechanisms of rephasal of circadian rhythms in response to a 180 deg phase shift /simulated 12-hr time zone change/

A model developed by Wever (1966) is considered. The model describes the behavior of circadian rhythms in response to photoperiod phase shifts simulating time zone changes, as a function of endogenous periodicity, light intensity, and direction of phase shift. A description is given of an investigation conducted to test the model upon the deep body temperature rhythm in unrestrained subhuman primates. An evaluation is conducted regarding the applicability of the model in predicting the type and duration of desynchronization induced by simulated time zone changes as a function of endogenous periodicity.

Deroshia, C. W.↗

NASA NTRS1979

Hand-held vital-signals monitor

Complete miniaturized physiological vital-signs monitor displays body temperature, heart rate, and breath rate, and has provision to display blood-pressure data fed from external circuitery.

Rinard, G. A.↗

NASA NTRS1978

Continuous metabolic and cardiovascular measurements on a monkey subject during a simulated 6-day Spacelab mission

An adult male pig-tailed monkey (Macaca nemestrina) with surgically implanted biotelemetry unit was inserted into a fiberglass pod system which was installed in a Spacelab mock-up to simulate a 6-day mission during which extensive physiological measurements were obtained. The purpose of the pod was to make possible the study of respiratory gas exchange. Body temperature and selected cardiovascular parameters were recorded continuously for 2.6 days prior to 'launch', 6.3 days during 'flight', and 1.8 days after 'landing'. The results are surveyed, and it is concluded that it is feasible to perform sound physiological experiments on nonhuman primates in the Spacelab environment

Pace, N.↗

NASA NTRS1978

Structures for hypersonic airbreathing tactical missiles

The studies to date were encouraging and indicated that materials were available or could be developed to satisfy scramjet requirements. Some of the more promising materials for the critical components were indicated. This information is summarized as follows : (1) radome - Slip cast fused silica is the current candidate, but others are being investigated. One shortcoming of slip cast fused silica is its susceptability to rain damage. (2) inlet leading edges - A refractory metal with a good oxidation protective coating will be required. Tantalum T222 with a Hafnia coating looks promising. (3) inlet ducts - An uninsulated refractory alloy will be required. Columbium F-85 was the best of those considered for the noncircular ducts. (4) external body - The external body temperatures are sufficiently low to permit the use of super alloys. (5) combustor and nozzle - The pyrolytic graphite/silicon carbide coating is very attractive for use in the combustor and nozzle areas.

Caywood, W. C.↗

NASA NTRS1978

Effect of sodium and calcium ingestion on thermoregulation during exercise in man

The effects of hypertonic sodium and calcium ingestion on body temperature during exercise in cool and hot environments are investigated. Rectal and mean skin temperatures, sweat rates and arm and leg total blood flows were measured in men during periods of rest, submaximal exercise and recovery at temperatures of 26.5 C and 39.4 C after ingestion of NaCl and CaCl2 solutions. In both environments, higher rectal temperatures are observed after hypertonic sodium ingestion, which is also associated with attenuated blood flow in the extremities, lower sweat rates and slightly higher skin temperature in the heat, indicating significant thermoregulatory responses. Hypertonic calcium and isotonic sodium cause no temperature change, although calcium caused a reduction of blood flow in the extremities.

Greenleaf, J. E.↗

NASA NTRS1979

Thermoregulation in unrestrained rats during and after exposure to 1.5-4 G

Unrestrained rats were exposed to cold for 1 h during and immediately after exposure to hypergravic fields (1.5-4 G) to determine if they recover their ability to thermoregulate on reentry to 1-G conditions. In contrast to the decreased body temperatures observed when cold exposure occurred concurrently with acceleration, hypothalamic, carotid, and brown fat temperatures did not fall when rats were exposed to cold immediately after return to 1 G. These results support the hypothesis that the thermoregulatory alterations seen under hypergravic conditions are manifestations of an effect of ongoing exposure to hypergravity and can be reversed on termination of acceleration. The reversibility of the thermoregulatory impairment is apparently unaffected by the magnitude of the acceleration field over a range of 1.5-4 G.

Giacchino, J.↗