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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Design methodology for a community response questionnaire on sonic boom exposure

A preliminary draft questionnaire concerning community response to sonic booms was developed. Interviews were conducted in two communities that had experienced supersonic overflights of the SR-71 airplane for several years. Even though the overflights had ceased about 6 months prior to the interviews, people clearly remembered hearing sonic booms. A total of 22 people living in central Utah and 23 people living along Idaho/Washington state border took part in these interviews. The draft questionnaire was constantly modified during the study in order to evaluate different versions. Questions were developed which related to annoyance, startle, sleep disturbance, building vibration, and building damage. Based on the data collected, a proposed community response survey response instrument was developed for application in a full-scale sonic boom study.

Farbry, John E., Jr.↗
NASA NTRS1990

Development of an Artificial Gravity Sleeper (AGS)

The design and construction of a 2-meter radius 'human compatible' centrifuge termed the Artificial Gravity Sleeper (AGS) is considered. The centrifuge will accommodate up to four subjects at a time, operate at a broad range of speeds, and have safety features. Experiments that will be conducted on the AGS will help to investigate the quality of sleep during 100 percent gradient centrifugation. A microgravity simulation also will be studied using bed rest to assess the ability of 100 percent gradient centrifugation to function as a countermeasure to cardiovascular deconditioning.

Cardus, David↗
NASA NTRS1992

Photic effects on sustained performance

Research is described which evaluates manipulating environmental light intensity as a means to attenuate fatigue. A counter balanced, within-subjects design was used to compare nine male subjects exposed to dim (100 lux) and bright (3000 lux) light conditions. Oral temperature values were greater for the bright light group over the dim light condition. Melatonin levels were suppressed by bright light treatment. Also, the frequency of eye blink rate was less for subjects during bright over dim light exposure. Light exposure was without effect on subjective fatigue. However, irrespective of light condition, significant effects on confusion, fatigue, and vigor mood dimensions were found as a result of 30 hour sleep deprivation. The findings suggest that bright lights may be used to help sustain nocturnal activity otherwise susceptible to fatigue. Such findings may have implications for the lighting arrangements on space flights during the subjective night for astronauts.

French, J.↗
NASA NTRS1991

Alertness management in flight operations - Strategic napping

Strategic napping in two different flight operation environments is considered to illustrate its application as a fatigue countermeasure. Data obtained from commercial short-haul and long-haul operations demonstrated the utility and current practices of strategic napping. A preplanned cockpit nap acted as an acute 'safety valve' for the sleep loss, circadian disruption, and fatigue that occurs in long-haul flying.

Rosekind, Mark R.↗
NASA NTRS1992

Therapeutic effectiveness of medications taken during spaceflight

The therapeutic effectiveness of medications during spaceflight is considered in light of extensive anecdotal and experimental evidence. Attention is given to a range of medications for space motion sickness, sleeplessness, and physical discomfort. About 70 individual cases are reviewed in which crewmembers used such medications as: (1) scopolamine hydrobromide, dextroamphetamine sulfate, and promethazine hydrochloride for motion sickness; (2) metoclopramide hydrochloride and naloxone hydrochloride for bowel motility; and (3) aspirin and acetaminophen for headache and back pain. The effectiveness of orally ingested medications for space motion sickness is shown to be very low, while promethazine hydrochloride is effective when administered intramuscularly. The medications for pain are shown to be generally effective, and the use of sleep-inducing medications is limited by potentially detrimental performance effects.

Pool, Sam L.↗
NASA NTRS1992

NASA Space Human Factors Program

This booklet briefly and succinctly treats 23 topics of particular interest to the NASA Space Human Factors Program. Most articles are by different authors who are mainly NASA Johnson or NASA Ames personnel. Representative topics covered include mental workload and performance in space, light effects on Circadian rhythms, human sleep, human reasoning, microgravity effects and automation and crew performance.

Source record↗
NASA NTRS1990

NASA/NSF Workshop on Antarctic Research

Viewgraphs that accompanied an Ames Research Center presentation address Ames' currently-supported life sciences activities. These include crew factor issues such as human, automation, and telecommunication systems; strategic behavior and workloads; sleep, fatigue, and circadian rhythms; and virtual reality and spatial instrumentation. The need, background, and examples of pertinent research are provided.

Connors, Mary M.↗
NASA NTRS1993

A comparison of low-gravity measurements on-board Columbia during STS-40

The first NASA Spacelab Life Sciences mission (SLS-1) flew 5 Jun. to 14 Jun. 1991 on the orbiter Columbia (STS-40). The purpose of the mission was to investigate the human body's adaptation to the low-gravity conditions of space flight and the body's readjustment after the mission to the 1 g environment of earth. In addition to the life sciences experiments manifested for the Spacelab module, a variety of experiments in other scientific disciplines flew in the Spacelab and in Get Away Special (GAS) Canisters on the GAS Bridge Assembly. Several principal investigators designed and flew specialized accelerometer systems to better assess the results of their experiments by means of a low-gravity environment characterization. This was also the first flight of the NASA Microgravity Science and Applications Division (MSAD) sponsored Space Acceleration Measurement System (SAMS) and the first flight of the NASA Orbiter Experiments Office (OEX) sponsored Orbital Acceleration Research Experiment accelerometer (OARE). A brief introduction to seven STS-40 accelerometer systems are presented and the resulting data are discussed and compared. During crew sleep periods, acceleration magnitudes in the 10(exp -6) to 10(exp -5) g range were recorded in the Spacelab module and on the GAS Bridge Assembly. Magnitudes increased to the 10(exp -4) g level during periods of nominal crew activity. Vernier thruster firings caused acceleration shifts on the order of 10(exp -4) g and primary thruster firings caused accelerations as great as 10(exp -2) g. Frequency domain analysis revealed typical excitation of Orbiter and Spacelab structural modes at 3.5, 4.7, 5.2, 6.2, 7, and 17 Hz.

Rogers, Melissa J. B.↗
NASA NTRS1993

Body fluid alterations during head-down bed rest in men at moderate altitude

To determine the effects of hypoxia on fluid balance responses to simulated zero-gravity, measurements were made in six subjects before and during -5 deg continuous head-down bed rest (HDBR) over 8 d at 10,678 ft. The same subjects were studied again at this altitude without HDBR as a control (CON) using a cross-over design. During this time, they maintained normal upright day-time activities, sleeping in the horizontal position at night. Fluid balance changes during HDBR in hypoxia were more pronounced than similar measurements previously reported from HDBR studies at sea level. Plasma volume loss was slightly greater and the diuresis and natriuresis were doubled in magnitude as compared to previous studies in normoxia and sustained for 4 d during hypoxia. These changes were associated with an immediate but transient rise in plasma atrial natriuretic peptide (ANP) to day 4 of 140 percent in HDBR and 41 percent in CON (p less than 0.005), followed by a decline towards baseline. Differences were less striking between HDBR and CON for plasma antidiuretic hormone and aldosterone, which were transiently reduced by HDBR. Plasma catecholamines showed a similar pattern to ANP in both HDBR and CON, suggesting that elevated ANP and catecholamines together accounted for the enhanced fluid shifts with HDBR during hypoxia.

Loeppky, J. A.↗
NASA NTRS1993

'And we were tired' fatigue and aircrew errors

Cooper, White, and Lauber analyzed jet-transport accidents worldwide for the period 1968 to 1976 and found more than 60 in which breakdowns of the crew-performance and decision-making process played a pivotal role. It is the contention of this paper that the results reported by Cooper, et al., are related to fatigue and that fatigue is related to sleep deprivation, circadian desynchronosis, and lack of good nutrition. It is further argued, and supporting research is cited, that fatigue does not cause loss of skill in flying the aircraft but may have disastrous effects on judgmental and decision-making functions.

Ritter, Richard D.↗
NASA NTRS1986

Foods and food constituents that affect the brain and human behavior

Until recently, it was generally believed that brain function was usually independent of day-to-day metabolic changes associated with consumption of food. Although it was acknowledged that peripheral metabolic changes associated with hunger or satiety might affect brain function, other effects of foods on the brain were considered unlikely. However, in 1971, Fernstrom and Wurtman discovered that under certain conditions, the protein-to-carbohydrate ratio of a meal could affect the concentration of a particular brain neurotransmitter. That neurotransmitter, serotonin, participates in the regulation of a variety of central nervous system (CNS) functions including sleep, pain sensitivity, aggression, and patterns of nutrient selection. The activity of other neurotransmitter systems has also been shown to be, under certain conditions, affected by dietary constituents which are given either as ordinary foods or in purified form. For example, the CNS turnover of two catecholamine neurotransmitters, dopamine and norepinephrine, can be altered by ingestion of their amino acid precursor, tyrosine, when neurons that release these monoamines are firing frequently. Similarly, lecithin, a dietary source of choline, and choline itself have been shown to increase the synthesis of acetylcholine when cholinergic neurons are very active. It is possible that other neurotransmitters could also be affected by precursor availability or other, as yet undiscovered peripheral factors governed by food consumption. The effects of food on neurotransmitters and behavior are discussed.

Lieberman, Harris R.↗
NASA NTRS1993

Exercise countermeasures for bed-rest deconditioning

The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

Greenleaf, John↗
NASA NTRS1993

New Mars free-air and Bouguer gravity: Correlation with topography, geology and large impact basins

Free-air and Bouguer gravity anomalies from a 50x50 field (MGM635), derived at the Goddard Space Flight Center, with global topography, geology, and the distribution of large impact basins was compared. The free-air gravity anomalies were derived from re-analysis of Viking Orbiter and Mariner 9 tracking data and have a spatial resolution of 250-300 km. Bouguer anomalies were calculated using a 50x50 expansion of the current Mars topography and the GSFC degree 50 geoid as the equipotential reference surface. Rotational flattening was removed using a moment of inertia of 0.365 and the corrections from Table B2 of Sleep and Phillips. Crustal density and mean density were assumed to be 2.9 and 3.93 gm/cm(sup 3). The spherical harmonic topography used has zero mean elevation, and differs from the USGS maps by about 2 km. Comparisons with global geology use a simplified map with about 1/3 the number of units on the current maps. For correlation with impact basins, the recent compilation by Schultz and Frey was used.

Frey, Herbert↗
NASA NTRS1994

Crew factors in flight operations 6: Psychophysiological responses to helicopter operations

Thirty-two helicopter pilots were studied before, during, and after 4-5 day trips providing support services from Aberdeen, Scotland, to rigs in the North Sea oil fields. Early on-duty times obliged subjects to wake up 1.5 hours earlier on trip days than on pretrip days. Consequently, they slept nearly an hour less per night on trips. They reported more fatigue on post-trip days than on pretrip days, suggesting a cumulative effect of duty-related activities and sleep loss. Fatigue and negative affect were higher, and activation lower, by the end of trip days than by the end of pretrip days. The earlier a subject went on duty, the lower his activation by the end of the day. Caffeine consumption increased 42 percent on trip days. The incidence of headache doubled, of back pain increased twelve fold, and of burning eyes quadrupled. In the aircraft studied, thermal discomfort and high vibration levels were common. The longer pilots remained on duty, the more negative their mood became.

Gander, Philippa H.↗
NASA NTRS1991

Measurement and modification of the EEG and related behavior

Electrophysiological changes in the sensorimotor pathways were found to accompany the effect of rhythmic EEG patterns in the sensorimotor cortex. Additionally, several striking behavioral changes were seen, including in particular an enhancement of sleep and an elevation of seizure threshold to epileptogenic agents. This raised the possibility that human seizure disorders might be influenced therapeutically by similar training. Our objective in human EEG feedback training became not only the facilitation of normal rhythmic patterns, but also the suppression of abnormal activity, thus requiring complex contingencies directed to the normalization of the sensorimotor EEG. To achieve this, a multicomponent frequency analysis was developed to extract and separate normal and abnormal elements of the EEG signal. Each of these elements was transduced to a specific component of a visual display system, and these were combined through logic circuits to present the subject with a symbolic display. Variable criteria provided for the gradual shaping of EEG elements towards the desired normal pattern. Some 50-70% of patients with poorly controlled seizure disorders experienced therapeutic benefits from this approach in our laboratory, and subsequently in many others. A more recent application of this approach to the modification of human brain function in our lab has been directed to the dichotomous problems of task overload and underload in the contemporary aviation environment. At least 70% of all aviation accidents have been attributed to the impact of these kinds of problems on crew performance. The use of EEG in this context has required many technical innovations and the application of the latest advances in EEG signal analysis. Our first goal has been the identification of relevant EEG characteristics. Additionally, we have developed a portable recording and analysis system for application in this context. Findings from laboratory and in-flight studies suggest that we will be able to detect appropriate changes in brain function, and feed this information to on-board computers for modification of mission requirements and/or crew status.

Sterman, M. B.↗
NASA NTRS1994

Basic features of the STS/Spacelab vibration environment

The Space Shuttle acceleration environment is characterized. The acceleration environment is composed of a residual or quasi-steady component and higher frequency components induced by vehicle structural modes and the operation of onboard machinery. Quasi-steady accelerations are generally due to atmospheric drag, gravity gradient effects, and rotational forces. These accelerations tend to vary with the orbital frequency (approx. 10(exp -4) Hz) and have magnitudes less than or equal to 10(exp -6) g(sub 0) (where 1 g(sub 0) is terrestrial gravity). Higher frequency g-jitter is characterized by oscillatory disturbances in the 1-100 Hz range and transient components. Oscillatory accelerations are related to the response of large flexible structures like antennae, the Spacelab module, and the Orbiter itself, and to the operation of rotating machinery. The Orbiter structural modes in the 1-10 Hz range, are excited by oscillatory and transient disturbances and tend to dominate the energy spectrum of the acceleration environment. A comparison of the acceleration measurements from different Space Shuttle missions reveals the characteristic signature of the structural modes of the Orbiter overlaid with mission specific hardware induced disturbances and their harmonics. Transient accelerations are usually attributed to crew activity and Orbiter thruster operations. During crew sleep periods, the acceleration levels are typically on the order of 10(exp -6) g(sub 0) (1 micro-g). Crew work and exercise tend to raise the accelerations to the 10(exp -3) g(sub 0) (1 milli-g) level. Vernier reaction control system firings tend to cause accelerations of 10(exp -4) g(sub 0), while primary reaction control system and Orbiter maneuvering system firings cause accelerations as large as 10(exp -2) g(sub 0). Vibration isolation techniques (both active and passive systems) used during crew exercise have been shown to significantly reduce the acceleration magnitudes.

Baugher, Charles R.↗
NASA NTRS1994

Extended duration orbiter medical project variability of blood pressure and heart rate (STS-50/USML-1)

Decreases in arterial baroreflex function after space flight may be related to changes in blood pressure and heart rate patterns during flight. Ambulatory blood pressure and heart rate were measured for 24 hours, in fourteen astronauts on two occasions before flight, two to three occasions in flight, and 2 days after landing on Shuttle missions lasting 4 to 14 days. Blood pressure and heart rate were recorded every 20minutes during awake periods and every 30 minutes during sleep. In pre- and postflight studies, the 24-hour ambulatory measurements were followed by studies of carotid baroreceptor-cardiac reflex responses. Carotid baroreceptors were stimulated using a sequence of neck pressure and suction from +40 to -65 mmHg.

Fritsch-Yelle, Janice M.↗
NASA NTRS1995

Neurodynamic oscillators

Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

Espinosa, Ismael↗