Adaptation of sleep and circadian rhythms was examined in three temperate zone dwellers arriving in Antarctica during summer. Rectal temperature, wrist activity, and heart rate were monitored continuously, sleep timing and quality noted on awakening, and mood and fatigue rated every 2 h while awake. Sleep was poorer in 2/3 subjects in Antarctica, where all subjects reported more difficulty rising. Sleep occurred at the same clock times in New Zealand and Antarctica, however, the rhythms of temperature, activity, and heart rate underwent a delay of about 2 h. The subject with the most Antarctic experience had the least difficulty adapting to sleeping during constant daylight. The subject with the most delayed circadian rhythms had the most difficulty. The delay in the circadian system with respect to sleep and clock time is hypothesized to be due to differences in zeitgeber strength and/or zeitgeber exposure between Antarctica and New Zealand.Abstract
Vision through a restricted field of view (RFOV) is becoming increasingly common in aviation with the use of helmet mounted displays. Our first experiment investigated the influence of a narrow (20° binocular RFOV on performance during head-free visuo-manual tracking of a wide range (±85°) horizontally moving target. Second, the effects of two levels of RFOV (20°, 70°)on a similar tracking task presented with various eccentricities were compared to full field of view (FOV). Eye and head movement around the yaw axis were recorded and analyzed versus headofroe visual pursuit alone. Tracking performance appeared moderately impaired when RFOV was set to 20° but did not improve with a 70° field. Discomfort due to unusually large head movements was ruled out as a causal factor. Visuo-manual tracking apparently implies a need for head stability. RFOV degrades this basic requirement which, in turn, could explain performance impairment. Analysis of eye-head coordination characteristics following FOV task conditions supports this hypothesis.Abstract
Good visual contrast sensitivity (CS) is often described as a visual capability important for success as a military aviator and so has been suggested as a physical standard for personnel selection and retention. To evaluate this idea, we measured the CS of 135 U.S. Navy fighter pilots ranging in age from 24 to 44 years (mean = 30.20, S.D. = 4.06) and compared these to the CS of non-aviators. We obtained the non-aviator data from published studies of other investigators who used similar procedures with the same widely used, commercially available apparatus (Nicolet CST 2000). In addition to this comparison, we correlated the pilots' CS with their air-to-air target detection distances measured during air combat maneuver training and to their night carrier landing performance scores. The major findings were: I ) The mean CS of the aviators and the non-aviators were within ± 1.0 S.D. of each other in most instances, and those few instances where a greater difference was found were parsimoniously explained by methodological and procedural factors; 2) sensitivities to different spatial frequencies were highly correlated among themselves, indicating much redundancy among the measurements; 3) there was no evidence of a relationship between CS and air-to-air target detection distances or night carrier landing performance.Abstract
The ratio of reabsorption of osmotically free water to osmolal clearance in individual urine voids was about the same before and after short-term spaceflights (the points fall on the same regression line). This ratio was reduced after long-term flights, so that the regression lines for pre- and postflight values have different slopes. This change in the function relating the two factors was accompanied by increased vasopressin in blood plasma and probably was caused by altered cellular reaction to vasepressin. The decrease in the effect of vasopressin may have been caused by development of hypokalernia and hypercalcernia in the cosmonauts, and decrease in cellular potassium in the outer renal medulla {this effect was observed in experiments on rats after flights on biosateliites). We established that, in addition to cAMP, cGMP and inositol trisphosphate participate in cellular reactions to vasepressin. Increases in the concentration of cGMP and decrease in the formation of inositol trisphosphate in the presence of neomycin increase the hydro-osmotic effect of vasopressin. We hypothesize that modulation of the effect of vasepressin in cosmonauts is due to change in the functional state of their kidneys.Abstract
In this study we have determined the effect of severe and moderate hypoxemia on plasma hypaxanthine and lactate values. Hypoxemia was induced in healthy humans in a low pressure chamber. The test subjects breathed atmospheric air at barometric pressures of 279 mm Hg and 385 mm Hg, representing o simulated altitude of about 7,620 and 5,334 m (25,000 and 17,500 ft), respectively. Exposure to 279 mm Hg represents a severe hypoxemia and all subjects exposed to this simulated altitude for 2 min showed symptoms related to hypoxia. After this exposure, plasma hypoxanthine increased by an average of 2.4 times compared to preexposure values. Exposure to 385 mm Hg represents a moderate hypoxemia and the persons tested at this simulated altitude for 45 min showed no or minor symptoms related to hypoxia and there was no change in plasma hypoxanthine values. In contrast to the unchanged plasma hypoxanthine values there was a 50% increase in plasma lactate values after 30 rain exposure. We conclude that plasma hypoxonthine is a reliable marker far severe cellular hypoxia in humans and that enhanced plasma hypoxanthine levels are a rapid response to cellular hypoxia.Abstract
We studied the effect of apomorphlne on the performance of rots, maintained on a free-operont shock-avoidance schedule under normoxic and hypexic (12, 10, and 8% O2) environments. In a normoxic environment, apomorphine (1, 2, 4, and 8 mg/kg, i.p.) produced stereotyped behaviors and dose-dependent increases in the rats' lever-pressing response rate. In a hypexic environment, however, the increase of the response rate induced by apomorphine at 1 mg/kg was suppressed by the hypoxic conditions tested. At a dose of 8 mg/kg apemorphine, it was also suppressed by exposure to severe hypoxia (10 and 8% O2). These results suggest that the impairment of avoidance behavior in rats by hypoxia was not always improved by apomorphine, and that the degree of improvement depends on the combined effects of the dosage of the drug injected, the degree of hypoxia, and the type of behavior observed.Abstract
The levels of histamine (HA) and tole-methylhistamine (t-MH) were determined in five brain regions of Suncus murinus (suncus) and the effects of motion stimulus or drugs influencing the turnover of these amines were studied to elucidate the role of histamine in motion sickness. Shaking the animals for 2 min increased HA contents in telencephalon and diencephalon without significantly changing the t-MH levels, a-Fluoromethylhistidine (α-FMH), which is presumed to deplete the neuronal HA, tended to raise the HA levels. α-FMH slightly alleviated the vomiting response to motion stimulus and suppressed the HA increase in diencephalon caused by shaking. Compound 48/80, which releases HA from mast cells, did not alter the control HA levels, but effectively prevented the motion sickness and completely suppressed the motion-induced rises in HA levels. These results provide further evidence that brain HA plays an important role in the development of motion sickness.Abstract
We have made a systematic experimental study since we proposed the Qigong (Q-G) maneuver in 1986. The purpose of this article is to summarize our 5-year research project. It describes the theoretical problems of the Q-G maneuver, including the mechanism of blood pressure elevation induced by the Q-G maneuver, analysis of the maneuver elements and their respective contribution, the theory and method of muscular contraction in the Q-G maneuver, and the theory and practice of seated posture in the anti-G maneuver. We also describe the characteristics of the Q-G maneuver in five aspects.Abstract
The effect of body composition an the thermal and metabolic responses of 24 male volunteers (20 to 35 years) was examined during 90 rain of moderately cold (18, 22, or 26°C) water immersion to the first thoracic vertebrae. Body composition was determined via underwater densiometry. Subjects were divided with respect to body fat (high fat (HF) = 18-22%, n = 12; Low fat (LF)= 8-12%, n = 12) and randomly assigned to one of three water temperatures. Rectal temperature (°c) after 90 rain of immersion did nat differ in LF and HF at 18° (35.9 vs. 36.2), 22°C (36.0 vs. 36.0), and 26° (36.0 vs. 36.3). Oxygen uptake (Vo2, ml - kg−1. min−1) was greater in LF than in HF in all water temperatures. Oxygen uptake at 90 min was greater for LF than HF in 18°C (11.48 vs. 9.19), 22°C (9.79 vs. 4.70), and 26°C (6.21 vs. 5.44). Mean skin temperature in LF and HF approached water temperature within the first 5 rain. Despite the thermal strain of cold water immersion, the LF subjects were able to maintain a similar Tre compared to the HF due to a significantly greater shivering thermogenesis.Abstract
A survey, replicating one originally conducted by the International Federation of Airline Pilots' Associations (IFALPAI in 1967, was carried out to investigate the aetiology of inflight incapacitation on commercial flight decks. The questionnaire was construtted by IFALPA and distributed worldwide by its member associations. Since response to the questionnaire was voluntary, no control of the sample population was possible. The results indicate that 29%of the 4,345 respondents had been incapacitated at least once. As in 1967, gastro-intestinal symptoms accounted for the majority (58%) of incidents, other main causes being symptoms of nasal and sinus congestion (‘blocked’ ear and sinus pain), headaches, and faintness or general weakness. Of those who had experienced an incident of incapacitation, 48% claimed that safety was actually, or potentially, affected. However, when all respondents were asked whether they were concerned about safety in the event of incapacitation inflight (excluding take-off and landing), only 25% expressed concern. Slightly more pilots operating in three-man crews (50.5%) thought incapacitation affected the safety of the flight than those operating in two-man crews (45.3%).Abstract
Aviators presenting for annual flight medical examinations at the 379th Strategic Hospital at Wurtsmith Air Force Base were studied to determine the prevalence of substandard visual acuity. The prevalence of the use of outdated (superseded) corrective lenses was also studied. We conducted 342 examinations on different aviators and 92 (26.9%) of these aviators were found to require corrective lenses. There were 23 (6.7%) aviators who were found to have inadequate visual acuity and 14 of these (4.1%) were found to be wearing superseded lenses. The visual screening method prescribed by the United States Air Force did not identify four of the aviators who wore superseded lenses. Three aviators were found to be wearing lenses obtained from civil sources. The study suggests that improvements could be made in U.S. Air Force visual screening and care.Abstract
This is a case report of a male undergraduate pilot student referred from the aerospace medicine service because of difficulty coping with stresses associated with undergraduate pilot training (UPT). Two phases of a short-term cognitive-behavioral treatment program were undertaken. The initial phase of treatment involved assisting the student to become aware of cognitive, behavioral, and physiological cues that were associated with increased levels of stress, and relaxation training. The second treatment phase involved stress inoculation strategies and coping procedures that were competency based, rather than mastery based. The latter had previously been unsuccessfully used by the student. Results indicated increases in self-reported stress management skills and in objective reports of training performance. Although generalizability of this study is limited, short-term cognitive behavioral therapy procedures are felt to be an important tool for improving the performance of UPT students, and may also reduce the probability of self-initiated elimination due to subjective stress complaints.Abstract
Because a large amount of general aviation activity occurs in Central Florida, we reviewed our admissions for victims of small airplane crashes. We identified 13 burn victims of small aircraft accidents over a 7-year period. Of the 13, 12 survived their burn injuries, an overall survival rate of 92%. The extent of burn injury, Abbreviated Burn Severity Index (ANSI), complications, other injuries and rehabilitation potential are reviewed. Burn injury resulting from small airplane crashes is usually survivable if the patient arrives at the Burn Center alive. These burn victims generally are highly motivated individuals, are easily rehabilitated, and continue productive lives. Small airports and local hospitals should be aware of burn center availability because of the usual major extent of the burn injury.Abstract
Superior situational awareness, on extraordinary awareness of the total flight environment and aerial combat situation, is a significant contributor to success in aerial engagement. Review of over 1,00O published sources has led to the formulation of situational awareness as being principally in the cognitive domain. Superior awareness involves exceptional sensitivity to performance-critical cues in the operational environment, an exceptional capacity to anticipate changes in system states and operational conditions, and the ability to act on those changes in a proactive mode. Three important constructs are described: 1) automatic information processing; 2) near-threshold processing; and 3) skilled memory. In combination, they constitute a pilot attribute which uniquely facilitates the full armamentarium of skills and abilities of the superior tactical pilot.Abstract
All air forces use routine medical examination to ensure the health of their pilots and flying safety. I compared pilot physicals in 12 air farces, and reviewed literature dealing mainly with routine medical examination of asymptomotic individuals. The discussion considers what should be done during the routine pilot examination to ensure flying safety, health and mission completion. General recommendations are given on ways to keep cost and effort within limits without foiling to achieve the objective. Methods to achieve this include differentiating the intervals between examinations in different age groups and inclusion of procedures only beyond a certain age. Caution is odvised when considering the inclusion of new procedures, and attention should be paid to whether such a test can be expected to produce unacceptable numbers of false positive results.Abstract
We summarised and tabulated the literature dealing with the electroencephalogram in pilot selection published since a review in 1976. The incidence of seizure development in healthy groups with epileptiform discharges in their EEGs was found to be very low. An alternative interpretation is offered of the significance of epileptiforrn discharges in these groups in the context of pilot selection, and a plea is made for international standardization of procedures in this area.Abstract
The question of whether sickle cell trait (SCT) is potentially dangerous to military aircrew personnel who have it and, consequently, whether such individuals should be allowed to fly in military aircraft is a very emotional issue. This article traces the evolution of how the U.S. military has dealt with the problem, and the present status of individuals with SCT in the U.S. military aviation community. Extensive studies and means for subjectively evaluating the problem were instituted by the Department of Defense in 1981, after making the decision not to restrict aircrew with the trait from aviation duties. All research projects and educational programs were abruptly stopped in 1985. Today, there are no actual restrictions on individuals with SeT for duty in the aviation and diving communities.Abstract
During his term as surgeon general, Maj. Gen. Harry G. Armstrong was interested in the French monument commemorating the balloon flight of John Jeffries, the first American aviator, and Jean Pierre Blanchard. Maj. Gen. Armstrong proposed to visit the monument, located in a French forest, and have it renovated with appropriate multi-national ceremonies. The monument is at the landing site of the first flight across the English Channel. The authors discovered the former and current condition of the monument in Guines, France and compare that monument, of interest to Maj. Gen. Armstrong, to a new monument named for him, the newly enlarged U.S.A.F. Armstrong Laboratory.Abstract