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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 NTRS1976

Cerebellar pressor response in the dog

A fastigial pressor response has been elicited in the anesthetized mongrel dog. Stimulation within the rostral portions of this nucleus results in mean arterial pressure rises up to 150 mmHg above control. A proportional tachycardia is simultaneously evoked which may rapidly attain heart rates of 190 beats/min above control levels. Peak tachycardias immediately subside and often the heart rate declines below control values during stimulation while arterial pressure remains elevated. When either the carotid sinuses were isolated by ligation or a bilateral vagotomy was performed, the fastigial tachycardia was sustained. The response could still be attained when submaximal doses of alpha-chloralose anesthesia or high levels of barbiturates (30-40 mg/kg) were given. Both portions of the response result from widespread sympathetic activation; however, buffering of the response through the baroreceptor reflexes is only demonstrated in the cardiac segment of the response.

Dormer, K. J.↗
NASA NTRS1977

Ocular accommodative changes in humans induced by positional changes with respect to gravity

Results are presented for an experimental study concerning ocular accommodation measurements in normal human subjects while they were rotated at a speed of 1 deg/sec about their naso-occipital axis. A few rotations were done about an interaural axis. It is shown that altering the head position with respect to gravity is followed by a change in ocular refraction, with the major change being in a lens-thickening or accommodative direction. Reasons for ascribing these changes to reflex changes in ocular accommodation are given. Arguments are presented relating this accommodative response to the utricles, which are nearly parallel to the earth horizontal.

Markham, C. H.↗
NASA NTRS1977

Vestibular functions and sleep in space experiments

Physical indices of sleep were continuously monitored in an owl monkey living in a chamber continuously rotating at a constant angular velocity. The electrophysiological data obtained from chronically implanted electrodes was analyzed to determine the chronic effects of vestibular stimulation on sleep and wakefulness cycles. The interaction of linear and angular acceleration on the vestibulo-ocular reflex was investigated in three rhesus monkeys at various angular accelerations.

Perachio, A. A.↗
NASA NTRS1978

Determination of carbon by the oxidation reduction reaction with chromium

Free carbon was determined in silicon and boron carbides in ash, oxides, and other materials by oxidation to carbon dioxide with a mixture of K2Cr2O7 + H2SO4. The determination was made from the amount of CR(6) consumed, by adding excess Mohr's salt and titrating with a standard solution of KMnO4. The amount of Cr(6) self reduced was determined in a blank test. Optimum oxidation and conditions were achieved when the volumes of 5% k2Cr2Oz and H2SO4 were equal. The mixture was boiled for 1-2 hours using a reflex condenser. The volume should not be reduced, in order to avoid an increase in the sulfuric acid concentration. The relative error was 4-7% for 0.005-0.04 g C and less than or equal to 3.5% for 0.1 g C.

Mashkovich, L.↗
NASA NTRS1978

The control and prevention of seizures in children, a developmental and environmental approach

The clinical effectiveness of neurophysiological and developmental factors in controlling and preventing seizure mechanisms is detailed. It is shown that as cortical control advances with maturation, it requires increasingly severe environmental adversity to release this residual defensive reflex mechanism. Administration of anticonvulsant drugs is discouraged because of possible undesirable neuronal effects on the very young brain.

Lewinn, E. B.↗
NASA NTRS1979

Subsonic longitudinal and lateral aerodynamic characteristics for a systematic series of strake-wing configurations

A systematic wind tunnel study was conducted in the Langley 7 by 10 foot high speed tunnel to help establish a parametric data base of the longitudinal and lateral aerodynamic characteristics for configurations incorporating strake-wing geometries indicative of current and proposed maneuvering aircraft. The configurations employed combinations of strakes with reflexed planforms having exposed spans of 10%, 20%, and 30% of the reference wing span and wings with trapezoidal planforms having leading edge sweep angles of approximately 30, 40, 44, 50, and 60 deg. Tests were conducted at Mach numbers ranging from 0.3 to 0.8 and at angles of attack from approximately -4 to 48 deg at zero sideslip.

Luckring, J. M.↗
NASA NTRS1979

Flow visualization studies of a general research fighter model employing a strake-wing concept at subsonic speeds

A systematic wind tunnel study was conducted in the Langley high-speed 7 by 10 foot tunnel to document, by oil-flow photographs, the surface flow patterns for configurations incorporating strake-wing geometries indicative of current and proposed maneuvering aircraft. The configurations employed combinations of strakes with reflexed planforms having exposed spans of 10 percent, 20 percent, and 30 percent of the reference wing span and wings with trapezoidal planforms having leading-edge sweep angles of approximately 30 deg, 44 deg, and 60 deg. Tests were conducted at Mach numbers of 0.3 and 0.5 and at angles of attack ranging from approximately 5 deg to 30 deg in 5 deg increments at 0 deg sideslip. The configurations incorporating the strake-wing geometries exhibited more organized flow patterns with smaller asymmetries to higher angles of attack than the corresponding configurations incorporating the wing-alone geometries did.

Luckring, J. M.↗
NASA NTRS1977

The robot's eyes - Stereo vision system for automated scene analysis

Attention is given to the robot stereo vision system which maintains the image produced by solid-state detector television cameras in a dynamic random access memory called RAPID. The imaging hardware consists of sensors (two solid-state image arrays using a charge injection technique), a video-rate analog-to-digital converter, the RAPID memory, and various types of computer-controlled displays, and preprocessing equipment (for reflexive actions, processing aids, and object detection). The software is aimed at locating objects and transversibility. An object-tracking algorithm is discussed and it is noted that tracking speed is in the 50-75 pixels/s range.

Williams, D. S.↗
NASA NTRS1979

Cardiopulmonary readjustments in passive tilt

The readjustment of cardiopulmonary variables in human volunteers at various tilt angles on a tilt board is studied. Five healthy subjects (18-31 yr) with thorough knowledge of the experimental protocol are tested, passively tilted from the supine to the upright position in 15-deg increments in random sequence. The parameters measured are cardiac output (Q), heart rate (HR), stroke volume (SV), minute and alveolar ventilation /V(E) and V(A)/, functional residual capacity (FRC), and arterial-end-tidal P(CO2) pressure difference. It is found that changes in Q and FRC are linearly related to the sine of the tilt angle, indicating that either reflexes are absent or their net effect is proportional to the effects of gravity. This is clearly not the case for other variables /HR, SV, V(E), V(A)/, where it is possible to demonstrate threshold values for the appearance of secondary changes.

Matalon, S. V.↗
NASA NTRS1979

Effect of prolonged hypodynamia on certain physiological functions in dogs

The behavior of 20 dogs whose mobility was restricted was experimentally investigated. Their reactions to hypodynamia were either active behavior or progressive general depression and increased muscular weakness. Arterial pressure, pressor sinocarotid reflex valve, body weight, pulse rate, body temperature, and plasma cholinesterase activity were monitered for 28 days. Results are reported.

Yaremenko, B. R.↗
NASA NTRS1980

Experimental gastric ulcers induced by immobilization and electric shock of rats and their pharmacotherapy

The mechanism of development of experimental gastric ulcers, induced in rats by combined immobilization and electric shock, was analyzed pharmacologically with peripheral neurotropic agents. It is concluded that: (1) The most marked preventive effect in the development of the experimentally induced gastric ulcers was displayed by agents capable of blocking the ascending activation system of the reticular formation. (2) Sympathetic fibers, which disrupt the trophism of the gastric wall, form the efferent portion of the reflex arc. (3) Gastric secretion does not appear to be the primary cause of ulceration.

Zabrodin, O. N.↗
NASA NTRS1980

Results of the investigation of the otolith function in manned space flights

The effects of conditions of long term and short term space flights on the otolith function of cosmonauts were investigated via pre and post examinations. The results show that after long term flight, the intensity of the otolith reflex increased and asymmetry occurred in the indicators of the otolith function. Large changes in terms of expression and duration in the indicators of the otolith function after long term flight as compared with short term flight were also noted.

Kornilova, L. N.↗
NASA NTRS1980

Life sciences experiments on Spacelab 1

The objectives and procedures regarding various biological experiments to be conducted on Spacelab 1 are reviewed. These include the mapping of the HZE cosmic ray particle flux within the Spacelab module, investigating the effects of nullgravity on circadian cycles in the slime mold, Neurospora crassa, and measuring nutations of the dwarf sunflower, Helianthus annus. Emphasis is placed on research regarding possible changes in vestibulocular reflexes, vestibulospinal pathways, cortical functions involving perception of motion and spatial susceptibility. Also discussed are experiments regarding erythrokinetics in man and the effects of prolonged weightlessness of the humoral immune response in humans.

Buderer, M. C.↗
NASA NTRS1980

Evaluation of biological models using Spacelab

Biological models of hypogravity effects are described, including the cardiovascular-fluid shift, musculoskeletal, embryological and space sickness models. These models predict such effects as loss of extracellular fluid and electrolytes, decrease in red blood cell mass, and the loss of muscle and bone mass in weight-bearing portions of the body. Experimentation in Spacelab by the use of implanted electromagnetic flow probes, by fertilizing frog eggs in hypogravity and fixing the eggs at various stages of early development and by assessing the role of the vestibulocular reflex arc in space sickness is suggested. It is concluded that the use of small animals eliminates the uncertainties caused by corrective or preventive measures employed with human subjects.

Tollinger, D.↗
NASA NTRS1980

Visually induced self-motion sensation adapts rapidly to left-right visual reversal

The experimental demonstration of a reversal of the circularvection (CV) phenomenon is reported. After one to three hours of active movement while wearing vision-reversing goggles, 9 of 12 stationary human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as the seen stripe motion. In addition, the subjects showed a 17% reduction in vestibulo-ocular reflex slow phase gain over their brief exposure period. It is noted that whether a subject demonstrated reversed CV within the allowed exposure period appeared to be correlated with CV strength produced with a narrow field stimulus.

Oman, C. M.↗
NASA NTRS1980

Results of the study of the vestibular apparatus and the functions of the perception of space in cosmonauts (pre- and post-flight observations)

The effect of the set of space flight factors caused a change in the activity of the vestibular apparatus and the spatial perception function. More significant and longer shifts were observed during expeditions of great duration. The detected disorders (increase in reactivity of the otolithic apparatus, decrease in sensitivity of the cupula receptor, deterioration in the perception accuracy, etc.) had a definite tendency to be restored. The primary damage to the otolithic reflex (changes were found in practically all the subjects) is probably caused by the specific effect of zero gravitation, and apparently, may be one of the trigger mechanisms for discrepancy in the activity of the sensory systems, disorders in the correcting function of the cerebellum, and central vestibular formations.

Yakovleva, I. Y.↗