Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “HEART”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Biomedical ultrasonoscope

An instrument with a single ultrasonic transducer probe and a linear array of transducer probes permitting three operator modes is described. An 'A' and an 'M' mode scanner were combined with a 'C' mode scanner and a single receiver is used. The 'C' scanner mode enables two-dimensional cross sections of the viewed organ. Video-produced markers enable measurement of the dimensions of the heart. COS/MOS integrated logic circuit components are used to minimize power consumption and permit battery operation.

Lee, R. D.↗
NASA NTRS1975

Application of a dedicated micro-processor for automatic data acquisition of load strain and acoustic-emission data

This paper describes an automatic system for acquisition, logging and analysis of stress, strain and acoustic emission data. The complete system is a combination of several standard items of equipment and a newly developed intelligent data logger which has the capability to send data directly to a large scale computer for reduction and plotting. The data logging and all interfacing with peripheral equipment are accomplished using digital electronics. The heart of the system is a four-bit microprocessor and digital cassette tape unit. The system, which is controlled by instructions from a cathode ray tube terminal, has the capability to transmit data from the cassette unit to a large computer via a time sharing option. Typical results are presented for acoustic emission count rate and total count curves superimposed on stress-strain diagrams for boron/epoxy advanced composites.

Wilson, G. H.↗
NASA NTRS1975

Lightweight fuel cell powerplant for Tug

The design and characteristics of a lightweight powerplant based on advanced cell technology to meet the requirements of the Space Tug are described. The powerplant can be operated off low-pressure hydrogen and oxygen rocket propellant tanks and avoid the need for a dedicated reactant supply. Product water can be condensed or not, depending on vehicle or payload requirements. The heart of the unit, the fuel cell power section, consist of lightweight, series-connected, alkaline cells, while the power section contains accessory components for reactant conditioning, distribution, and venting, coolant circulation, passive product water removal and electric control. The proposed design offers at least a 50 per cent saving in powerplant weight, so that the total estimated powerplant dry weight including structure, tubing, wiring, interface connectors, and interface heat exchanger is 48 lb.

Handley, L. M.↗
NASA NTRS1975

Explorer 45 /S3-A/ observations of the magnetosphere and magnetopause during the August 4-6, 1972, magnetic storm period

The Explorer 45 (S3-A) satellite performed extensive field and particle measurements in the heart of the magnetosphere during the double magnetic storm period of August 4-6, 1972. Both the ground level magnetic records and the magnetic field deformations measured along the orbit by the satellite indicated the existence of only a moderate ring current. This was confirmed by the measurements of the total proton energy density by the on-board particle detectors, which showed a maximum energy density less than the densities observed during the December 1971 and June 1972 magnetic storms. The plasmapause in the noon quadrant was eroded continuously from the onset of the first storm at the beginning of August 4 to an altitude below L = 2.07 at about 1800 hours on August 5. Throughout the entire orbit during which the second sudden commencement occurred, a large amount of low-frequency electric and magnetic field noise was encountered. The most remarkable observation during this orbit was the contraction of the magnetopause to distances inside the satellite location at L = 5.2.

Hoffman, R. A.↗
NASA NTRS1976

Search for correlation between geomagnetic disturbances and mortality

A search is conducted for a possible correlation between solar activity and myocardial infarction and stroke in the United States. A statistical analysis is performed using data on geomagnetic activity and the daily U.S. mortality due to coronary heart disease and stroke for the years 1962 through 1966. None of the results are found to yield any evidence of a correlation. It is concluded that correlations claimed by Soviet workers between geomagnetic activity and the incidence of various human diseases are probably not statistically significant or probably are not due to a causal relation between geomagnetic activity and disease.

Lipa, B. J.↗
NASA NTRS1976

Role of arterial baroreceptors in mediating cardiovascular response to exercise

Experiments were conducted to define the role of the major arterial baroreceptors during moderately severe exercise by comparing the responses of untethered conscious dogs instrumented for the measurement of aortic pressure and cardiac output with those of dogs with total arterial baroreceptor denervation. The reflex heart rate responses to intravenous bolus doses of methoxamine were also examined in intact animals, both at rest and during exercise. Methoxamine is found to cause striking bradycardia at rest, but little bradycardia during exercise. Experimental findings suggest that the arterial baroreceptor reflex is normally inhibited during severe exercise and therefore plays little role in modulating the cardiovascular response to exercise.

Mcritchie, R. J.↗
NASA NTRS1976

Pre- and postflight systolic time intervals during LBNP - The second manned Skylab mission

Before and after the 59 day Skylab 3 flight, the astronauts were stressed with lower body negative pressure (LBNP), and their vectorcardiograms, pneumograms, phonocardiograms, and carotid pulse tracings were monitored together with the intervals of systole. In the immediate postflight period elevations in heart rate and blood pressure were observed in response to -50 mm Hg of LBNP. Postflight abnormalities in the systolic time intervals (STI) at rest and during stress were due to an increase in afterload and a decrease in preload. As blood volume was restored and blood pressure reduced, STI abnormalities persisted as long as one month, suggesting a possible reduction in ventricular contractility and/or a functional impairment to venous return.

Bergman, S. A., Jr.↗
NASA NTRS1976

Exercise cardiac output following Skylab missions - The second manned Skylab mission

Cardiac output was measured during preflight and postflight exercise-stress tests on the Skylab astronauts. In the postflight tests immediately following the 28-, 59-, and 84-d earth orbital missions, the astronauts exhibited an approximate 30% decrease in cardiac output coupled with an approximate 50% decrease in cardiac stroke volume during exercise. These changes were accompanied by elevated heart rates and significant increases in total systemic peripheral vascular resistance. Mean arterial pressure was unchanged. All parameters returned to normal preflight values within 30 d of the end of the orbital period. Duration of the zero-G exposure did not appear to influence either the magnitude of the hemodynamic changes or the time-course of their return to normal. These results are discussed in relation to other cardiovascular findings and possible mechanisms responsible for the observations are outlined.

Buderer, M. C.↗
NASA NTRS1976

Physiologic and anti-G suit performance data from YF-16 flight tests

Biomedical data were collected during high-G portions of 11 YF-16 test flights. Test pilots monitored revealed increased respiratory rate and volume, decreased tidal volume, and increased heart rate at higher G levels, with one pilot exhibiting various cardiac arrhythmias. Anti-G suit inflation and pressurization lags varied inversely with G-onset rate, and suit pressurization slope was near the design value.

Gillingham, K. K.↗
NASA NTRS1976

Cardiovascular function during sustained +G/z/ stress

The development of aerospace systems capable of very high levels of positive vertical accelerators stress has created a need for a better understanding of the cardiovascular responses to acceleration. Using a canine model, the heart and cardiovascular system were instrumented to continuously measure coronary blood flow, cardiac output, left ventricular and aortic root pressure, and oxygen saturation in the aorta, coronary sinus, and right ventricle. The animals were exposed to acceleration profiles up to +6 G, 120 s at peak G; a seatback angle of 45 deg was simulated in some experiments. Radiopaque contrast medium was injected to visualize the left ventricular chamber, coronary vasculature, aorta, and branches of the aorta. The results suggest mechanisms responsible for arrhythmias which may occur, and subendocardial hemorrhage which has been reported in other animals.

Erickson, H. H.↗
NASA NTRS1976

The effect of low light intensity on the maintenance of circadian synchrony in human subjects

Experiments were conducted on six healthy male subjects aged 20-23 yr and exposed for 21 days in a confined regulated environment to 16L:8D light:dark cycle with a view toward determining whether the light environment of 16L:8D at the relatively low light intensity of 15 ft.c. is adequate for the maintenance of circadian synchrony in man. The light intensity was 100 ft.c. during the first seven days, reduced to 15 ft.c. during the next seven days, and increased again to 100 ft.c. during the last seven days. Rectal temperature (RT) and heart rate (HR) were recorded throughout the three phases. In the 100 ft.c. regime, the RT and HR rhythms remained stable and circadian throughout. It is shown that 15 ft.c. light intensity is at or below threshold for maintaining circadian synchrony of human physiologic rhythms marked by instability and internal desynchronization with degradation of performance and well-being.

Winget, C. M.↗
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 NTRS1976

Body size and chronic acceleration

Experiments were conducted to study body composition as a function of acceleration (1-4.7 G) in mice and rats. It is shown that fat-free body mass is a predictable function of acceleration, and that of nine components of the fat-free body mass only skeletal muscle, liver and heart contributed to observed changes induced by delta G. Fat-free body mass was found to pass through a maximum at 1 G when it was plotted vs G for mice, rats and monkeys (1-4.7 G) and men (0-1 G).

Pitts, G. C.↗
NASA NTRS1976

Polyphosphazenes - New polymers with inorganic backbone atoms

Unique and useful properties of the class of nonhydrocarbon, nonhalocarbon, nonsilicone polymers known as polyphosphazenes are discussed at length. These polymers, with molecular weights to 4 million (degree of polymerization 15,000), can be fabricated as tubes, fibers, woven fabrics, flexible films, or plates, and many variants are stable to attack by water, bases, aqueous acids, jet fuels, oils, hydraulic fluids, gasoline, or other hydrocarbons. Rubbery polymers with these properties can be fashioned into flexible hose, fuel hose, gaskets, or O-rings. Since they do not provoke clotting reactions in blood, and reveal no carcinogenic effects to date, they are considered for internal prosthetic applications (replacement bone, temporary skin, heart valves), as biodegradable suturing material, as carriers for slow release of drugs, and as carriers for chemotherapeutic agents against cancers.

Allcock, H. R.↗
NASA NTRS1976

Space motion sickness medications - Interference with biomedical parameters

The possibility that drugs administered to Skylab 3 and 4 crewmen for space motion sickness may have interfered with their biomedical evaluation in space is investigated. The mixture of scopolamine and dextroamphetamine produced changes which allow a more valid interpretation of the early biomedical changes ocurring in weightlessness. There is no doubt that the dramatic increase in aldosterone excretion is not attributable to the drug, while the drug could have contributed to the in-flight changes observed in cortisol, epinephrine, heart rate and possibly urine volume.

Vernikos-Danellis, J.↗
NASA NTRS1976

Potential biomedical applications of ion beam technology

Electron bombardment ion thrusters used as ion sources have demonstrated a unique capability to vary the surface morphology of surgical implant materials. The microscopically rough surface texture produced by ion beam sputtering of these materials may result in improvements in the biological response and/or performance of implanted devices. Control of surface roughness may result in improved attachment of the implant to soft tissue, hard tissue, bone cement, or components deposited from blood. Potential biomedical applications of ion beam texturing discussed include: vascular prostheses, artificial heart pump diaphragms, pacemaker fixation, percutaneous connectors, orthopedic pros-thesis fixtion, and dental implants.

Banks, B. A.↗
NASA NTRS1976

Biomedical technology transfer: Applications of NASA science and technology

The major efforts of the Stanford Biomedical Applications Team Program at the Stanford University School of Medicine for the period from October 1, 1975 to September 31, 1976 are covered. A completed EMG biotelemetry system which monitors the physiological signals of man and animals in space related research is discussed. The results of a pilot study involving lower body negative pressure testing in cardiac patients has been completed as well as the design and construction of a new leg negative pressure unit for evaluating heart patients. This technology utilizes vacuum chambers to stress the cardiovascular system during space flight. Laboratory tests of an intracranial pressure transducer, have been conducted. Extremely stable long term data using capacative pressure sensors has lead to the order of commercially manufactured monitoring systems base. Projects involving commercialization are: flexible medical electrodes, an echocardioscope, a miniature biotelemetry system, and an on-line ventricular contour detector.

Source record↗
NASA NTRS1975

Tutorial: angiocardiography, past and present

The contribution of X-ray methodology and angiocardiography in the ability to study cardiac and cardiovascular function is presented. Angiocardiography remains the most reliable method for determination of overall chamber size and shape particularly in the face of disease states of varying etiologies. It also presents the most accurate means for obtaining dimensional information concerning the heart and blood vessels without the use of surgery or attachment of transducers.

Sandler, H.↗