Aviat Space Envir Md
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A comprehensive review of helicopter accident data from ACC sources is presented for the period 1971-1982. Accident and fatality rates have declined from the high values quoted in earlier studies in the 1960's and are now similar to those of fixed wing aircraft equipped with ejection seats. This improvement is related to the replacement of older reciprocating engined helicopters by turbine powered units and parallel progress in helicopter design, aircraft servicing, and pilot training. ⋯ Particular attention is paid to subsidiary aetiologies such as tail rotor strikes, disorientation, and ground accidents. Helicopter accidents involving fatalities on Operation Corporate are mentioned briefly. Methods whereby occupant protection and aircraft crashworthiness can be improved are covered and it is concluded that assisted escape, although an ideal solution, is by no means an urgent requirement for helicopters, in view of the dramatic reduction in accident and fatality rates.
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Aviat Space Envir Md · Feb 1985
Comparative StudyCarbohydrate metabolism in U.S. Navy submarine personnel.
One- and two-hour postprandial glucose and insulin values were measured in 58 submariners with 5 or more FBM patrols and in 58 non-submariners. An interrelationship between serum glucose and insulin for classifying defects in carbohydrate metabolism indicated that 55% of the submariners and 45% of the non-submariners exhibited some type of defect. Exercise appears to play an important role in the maintenance of normal carbohydrate metabolism in these subjects. ⋯ Negative correlation between exercise vs. 1 and 2-h glucose and 2-h insulin was significant for all subjects. An inverse relationship was observed between amount of exercise and the severity of carbohydrate metabolic defects in submariners and non-submariners as well as in normal weight and obese individuals. No statistical differences were found between the submariner and non-submariner groups with respect to age, % body fat, fatness (normal or obese), glycosylated hemoglobin, or family history of diabetes.
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The effects of saline or atropine injection (2 mg, im) on eccrine sweating and performance time in seven healthy male subjects were evaluated during treadmill walking (1.34 m X s-1) in a hot-dry environment (Ta = 49 degrees C, Tdp = 20.5 degrees C) before and after heat acclimation (HA). Mean skin temperature (Tsk), rectal temperature (Tre), and heart rate (HR) were continuously measured. Sweat loss from the skin (Msw) was calculated by changes in body weight. ⋯ The change in Tre X min-1 (delta Tre/delta t) was lower (p less than 0.05) in atropine-injected subjects following heat acclimation, and their worktime was improved by an average of 23.5 min (p = 0.08). These data demonstrate that heat acclimation improves the endurance time of atropine-treated subjects in a hot-dry environment. This improvement was, in part, due to the potentiation of sweat gland activity enabling greater evaporative cooling for the same dose of atropine.
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Aviat Space Envir Md · Apr 1984
Comparative StudyCoagulation and fibrinolytic responses to exercise and cold exposure.
This study examined the effect of acute cold exposure on coagulation (PTT) and fibrinolysis (ELT), and the effect of cooling on subsequent exercise-induced coagulation and fibrinolytic responses. Ten male volunteers were tested at 5 degrees C and 28 degrees C on alternate days. Each subject began by sitting quietly for 60 min. ⋯ ELT was shortened to 74, 62, and 44% while HCT increased to 107, 107, and 111% of pretest values for CR, NE, and CE, respectively. No significant change was noted for PTT. It is concluded that acute cold exposure as well as exercise stress results in an increase in ELT activity of blood; simultaneous enhancement of the coagulation status of the blood in response to stress is not inextricably linked to an elevation of fibrinolytic activity, a result that questions the importance of the Hageman factor dependent pathway between coagulation and fibrinolysis.
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Although acute mountain sickness (AMS) has been studied for well over a century, a standard measure or index of the degree of illness for use in experimental research does not exist. This paper outlines a definition and procedures for an operational measurement of AMS using the Environmental Symptoms Questionnaire (ESQ). After 58 men completed over 650 ESQs during a stay of 1-3 weeks atop Pike's Peak (4300 m), factor analysis produced nine distinct symptom groups, with two factors representing AMS. ⋯ Signal detection theory was used to establish a criterion score value for each factor. Standard deviation values were used to derive indices of sickness severity. Discussion is given to the possible relationships between the two types of AMS and the more serious conditions of cerebral and pulmonary edema.