The complex interaction of cold stress with environmental and organismic variables in exercising influence on human performance is a problem that still requires extensive investigation. Some relatively well-known interactions of cold with other stressors are reviewed. A description of the functioning of thermoregulative mechanisms in relation to cold stress and cold injury as a result of exposure in extreme climates is presented. Ways and means of counteracting cold stress to improve task performance are emphasized. The literature relating personnel selection, acclimatization, training, indoctrination, leadership, morale, and physical protection to the mitigation of cold stress and to measures of performance effectiveness is reviewed. Despite the paucity of meaningful data, it is felt that adequate and encouraging progress is being made in the understanding of the psychophysiology of cold stress.
The effects of moderate cold stress on bare or lightly covered hands was determined on five subjects exposed to alternate cycles of hand cooling at rest in a 0° C controlled environmental chamber and rewarming at rest in a room at 24° C. Repeated cycles of hand cooling and rewarming were characterized by a decrease in time for the hands to become cold and an increase in time for the hands to become warm, resulting in a progressively decreasing percentage of the elapsed time spent in the cold environment. Although the subjects were adequately clothed except for hand covering, body and skin temperatures fluctuated in relation to the exposure to the cold or warm environment. A relatively steady decrease in rectal temperature throughout the duration of the experimental period indicates that much of the heat loss from the hands was replaced by heat from the body "core" even though the hands were rewarmed in a warm environment. It appears that clothing adequate to protect the body will not prevent deep body heat loss from exposed hands, and other approaches to the problem of performing delicate manual tasks in a cold environment must be considered.
This report concerns travel and survival on Arctic sea ice. Information is totally derived from literature and deals mainly with Alaskan Eskimo practices but includes some from areas of the Canadian Arctic. Much of the information is anecdotal and unsystematic observation made by pioneers and explorers familiar with the Arctic and the Eskimo. The report lists environmental phenomena or "stimuli" which are likely to occur in the Arctic, and the activities or "responses" which the sea ice traveler must make in order to cope with these external forces or to utilize resources which the environment provides. The author has segregated a series of external forces and resources, and has suggested one or several ways to deal with them. These are divided into the physical environment and biological environment. The first includes temperature, wind, precipitation, atmospheric phenomena, astronomical phenomena, and the sea ice itself. The second includes all sources of energy available to the sea ice hunter: invertebrates, fish, birds and mammals.
The Wolff Integrating Motor Pneumotachograph was utilized to determine oxygen consumption of men traveling on foot, on snowshoes or on skis. As expected, the energy cost of walking in unbroken snow was greater than that of any other activity studied. The advantage of wearing snowshoes in deep snow varied greatly, evidently according to the skill of the wearer. The authors concluded that when the subject is wearing skis, the most efficient speed for covering a long distance is best determined by the subject himself, since caloric cost is approximately independent of speed within a reasonable range of speeds.
Arctic Aeromedical Laboratory. Aerospace Medical Division, Alaska Force Systems Command. Fort Wainwright, Alaska. Technical documentary report TDR-63-14. 10 p.
Arctic Aeromedical Laboratory. Aerospace Medical Division, Alaska Force Systems Command. Fort Wainwright, Alaska. Technical documentary report TDR-63-14. 10 p.
The purpose of this study was to determine what effect the usual dosage of acetylsalicylic acid (aspirin) would have on the normal pattern of cold defense in man. Seven subjects participated in the experiment, with three exposures per subject conducted at 4° C. Subjects received ten grains of aspirin in one exposure and a ten-grain placebo in the second; the third exposure was a control with no capsule given. Results of these exposures are shown in graphs of skin and rectal temperatures. A discussion of the results is presented. The usual dosage of acetylsalicylic acid in itself appears to have no significant effect on the normal pattern of cold defense in man. There was a psychogenic reaction when a placebo or aspirin was administered.
Arctic Aeromedical Laboratory. Aerospace Medical Division, Alaska Force Systems Command. Fort Wainwright, Alaska. Technical documentary report TDR-62-14. 21 p.
Department of Physiology, School of Medicine, University of California at Los Angeles
Source
Arctic Aeromedical Laboratory. Aerospace Medical Division, Alaska Force Systems Command. Fort Wainwright, Alaska. Technical documentary report TDR-62-14. 21 p.
In six cats bipolar stainless steel electrodes were stereotactically implanted in septai and hypothalamic loci. Observations were made of autonomic, somatomotor and behavioral responses to electrical stimulation delivered while the cats were unanesthetized and unrestrained. Septal stimulation evoked sympathetic and parasympathetic responses in varying combinations on various days. This suggested that responses to septal stimulation were influenced by the relative excitability of anterior and posterior hypothalamic neurons at a given time. Shivering was produced during stimulation of both septal and hypothalamic loci, thereby confirming previous results obtained from anesthetized preparations.
The object of this study was to determine possible differences in the course of salmonellosis in mice maintained at 25° C and others kept at 5° C, and to uncover, if possible, mechanisms responsible for such differences. The LD50 dose for mice of Salmonella typhimurium, strain RIA, is 4.6 X 105 for animals individually housed without bedding and maintained at 25° C. It is 3.8 X 10³ for animals similarly housed but kept at 5° C. An intravenous injection of 0.1 ml of saccharated iron oxide (Proferrin) two hours prior to infection lowers the LD50 to 4.9 X 10³ and 4.0 X 10 for mice kept respectively at 25° C and at 50 C. Low environmental temperature and "blockage" of the reticuloendothelial system (RES) lower the resistance of mice to about the same degree, but low temperature and RES impairment together lower resistance as if each is acting independently. Doubling the volume of Proferrin more than doubles the change in susceptibility to infection manifested by the mice but this amount seems to be toxic for mice. Even more important is the incidence of staphylococci found in liver or kidney of mice infected with S. typhimurium and kept at 5° C. Cultures were made on animals that survived infection for a period of 14 days and, except for the largest challenge doses where only a few animals remained, the incidence of staphylococci was proportional to the number of salmonellae injected. At 25° C only a small percentage of mice have staphylococci in tissues and these occur independent of the infectious dose of salmonellae.
In both accidental and surgical hypothermia, the chief hazard to life is the occurrence of ventricular fibrillation. Glycine, an amino acid,, has been used to inhibit cyclopropane-epinephrine induced arrhythmias, and this compound was evaluated in the prevention of arrhythmias due to lowered body temperatures. Mongrel dogs were used; pH, blood pressure, electrocardiograms, plasma potassium, and blood sugar were determined at frequent intervals during cooling. Control animals, receiving no medication were cooled to terminus and the incidence of ventricular fibrillation was 96%. A second group receiving glycine, 1.5 to 2.0 gm./kg., was cooled to terminus, and the incidence of fibrillation was reduced to 0%. In animals cooled to a reduced temperature of 24° C and subjected to a right thoracotomy, right ventriculotomy, and 10 minutes' venous occlusion, the incidence of ventricular fibrillation was 93%; the frequency of fibrillation in glycine treated animals during hypothermic cardiac surgery was 29%. Glycine treated animals exhibited significantly higher blood sugar and plasma potassium levels during hypothermia. The most likely explanation of the antiarrhythmic effect of glycine in hypothermia appears to be its ability to increase plasma potassium concentration.
The annotated bibliographies in this series include the following titles issued as separate publications: I. The Basic Psychology of Group Behavior. II. Dimensions of Group Structure and Group Behavior. III. Environmental Stress and Behavior Ecology. IV. Organizational Staffing. V. Organizational Management and Leadership, VI. Leadership in Formal Groups.
In addition, a special methodological review of approaches to the analysis of sociometric data has been prepared as a separate report.
The present report, Basic Psychology of Group Behavior, is organized in six sections: A. General Studies and Reviews, B. Roles, Status and Intra-Group Interactions, C. Communication and Information, D. Individual Perceptions in Group Behavior, E. Attitudes and Attitude Change, and F. Methodological Studies.
INTRODUCTION The disposal of excreta and other wastes at isolated sites in the arctic presents a problem which has not yet been solved satisfactorily. The use of latrines or pit privies is satisfactory as a temporary measure for small units for short periods of time, but for permanent or semi-permanent sites, and for larger numbers of men, an improved type of disposal is desirable. Due to the difficulty in obtaining water in adequate quantities, particularly during the winter months at sites located at high altitudes, and the problems associated with water and waste water disposal, water carriage has not proven satisfactory for use in these areas. It was the purpose of this study to devise a system for the complete destruction and disposal of human wastes in the arctic through the use of a system in keeping with the high degree of scientific equipment found at arctic Air-Force bases.
This review of medical and scientific literature was undertaken to establish what knowledge was existent regarding effects of alcohol and other drugs in the presence of reduced environmental temperatures on the behavior of animals and man. The gathering, classifying, and reviewing of this literature was necessary to determine whether further work should be done in this area. The paramount problem was to determine whether reduced environmental temperatures such as might be expected in environments in which Air Force personnel would be operating in their world-wide mission were a factor which should be considered in predicting behavior1 following the ingestion of alcohol, taking of drugs or exposure to other agents which might have effects on the central nervous system. This review was accomplished in part by direct reference to journals dealing with the action of drugs and environmental agents1 and in part by reference to standard abstracting sources. Special attention was paid to material appearing in the Quarterly Journal of Studies on Alcohol. Wherever the subject matter seemed of sufficient importance to require critical review of original data1 the original articles were sought out and analyzed. In a111 more than 4, 500 articles and abstracts were read. Of these, 1200 were selected as being especially pertinent and 700 of these were carefully reviewed. A cross-index was prepared according to major topic headings. Due to the paucity of material pertaining to the subject of the environment1 the original scope of the project was enlarged to consider information which would be requisite to an experimental investigation of the problem. Special attention was directed toward the pharmacology, physiology, effects on the nervous system, and behavior following acute or repeated intake of alcohol. Numerous observations have been made regarding the effect of alcohol alone. Relatively few have been made concerning the combinations of alcohol with other drugs. Practically no information was available concerning the effect of the environment, drugs and chemicals, especially as regards reduced temperatures. Based on the literature review, a narrative description of the material necessary to evaluate the original problem was made and recommendations were set forth for an experimental program which would obviously have to be carried over some period of time in order to clarify the many undetermined factors relating to the effects of alcohol alone and in combination with other drugs as influenced by reduced ambient temperatures.
This report summarizes experimental results obtained in the elevation of the effect of alcohol alone and in combination with other drugs as influenced by decreased environmental temperatures. The acute toxicity of ethyl alcohol was doubled by 24 hours exposure to 0-5° C, immediately prior to administration of the test. Cold exposure of 2, 24 or 168 hours did not materially affect the height of the blood alcohol level, nor was there any difference in the time required to reach maximum blood concentrations in animals given single doses. There were no significant differences in the alcohol blood/brain and brain/breath ratios resulting from short or prolonged exposures to cold. Motor coordination, as measured by ability to maintain equilibrium, deteriorated significantly in animals exposed to cold for 168 hours and administered small doses of alcohol. A further difference in deterioration of performance did not occur at higher doses of alcohol or later than 30 minutes after the dose was administered. While the percent of absorption of alcohol administered orally is greater with small doses than with the large, per unit of time, cold had no significant effect on over-all absorption rate. Rates of alcohol metabolism were not significantly altered by either acute or prolonged cold exposure, though body temperatures were altered significantly. When animals were habituated by receiving an aqueous solution of alcohol as their only source of fluid intake, equilibrium was impaired to a greater extent in some cold-exposed groups, the total increase in body weight per unit of time was depressed, the absorption rate was greater and oxidation rate slower than in groups habituated at room temperature. While the blood pentobarbital concentration was increased in animals exposed to cold for long periods, cold alone had no effect on the sleeping time induced by pentobarbital, and affected the increased sleeping time resulting from the simultaneous administration of alcohol and pentobarbital only when the two drugs were given within a short interval and the dose of alcohol was low. Chlorpromazine had a bivalent effect on body temperature, raising the temperature in animals exposed to cold and lowering the temperature in animals maintained at room temperature or when given to cold exposed animals in combination with alcohol. Cold had a brief effect on the impairment produced by alcohol and chlorpromazine together. Present data do not indicate a prolongation of the time during which performance is impaired due to the combined effects of chlorpromazine, ethyl alcohol, and cold.
Mice made tolerant to bacterial endotoxin show an increase in rate of carbon clearance from the blood and a greater stability of liver tryptophan pyrrolase following endotoxin poisoning compared with normal mice. Injections of actinomycin D, but not of ethionine nor 2-thiouracil, prevent these changes associated with tolerance. Animals exposed to 5° C cold are capable of being made tolerant despite their increased sensitivity to endotoxin. Acclimatization to cold reduces this sensitivity. Neither hemagglutinins against endotoxin coated erythrocytes nor bacterial agglutinins show any change of titer in tolerant animals. It is believed that the phenomenon of tolerance is dependent upon enzymatic stabilization.
Fifty-one species and subspecies of fleas are currently known in Alaska; 37 species normally occur on mammals, and 14 are associated with birds. With the possible exception of one or two species, none are restricted to the political entity, Alaska. From a study of geography, paleozoology, morphology and taxonomy, the fleas of Alaskan mammals are reported to be derived from three principal faunas. The largest group apparently arose from Eurasia as the mammals migrated across the Bering Land Bridge during the glacial periods of the Pleistocene epoch and earlier. These animals found refuge in a large nonglaciated area of interior Alaska and the Yukon Territory. These fleas are now common to both the Nearctic and Palearctic regions, their hosts generally being Holarctic in distribution. The second group of fleas are Nearctic in origin and have migrated northward along with their hosts as the Pleistocene glaciers receded. A number of the genera in this second group are restricted exclusively to the Nearctic region; however, certain genera are also represented in Eurasia. A third group of fleas arose from the Pacific Northwest. These fleas, like the second group, have spread northward as the Pleistocene glaciers receded. Fleas of this third group now occupy a narrow strip of land, mostly west of the Coast and Alaska Ranges. A study of host associations reveals that distribution of the fleas is not concordant with that of the preferred hosts. For example, of six species as so dated with microtine rodents in the taiga, only two have followed the same hosts into the vast tundra region to the north. Fleas originally thought to be restricted to the Arctic regions are now known to have adapted to hosts within the taiga, albeit the distribution is not an extensive one. These distribution patterns indicate that the Siphonaptera are subject to ecological factors and pressures over and above those which affect the distribution of the mammals and birds upon which they depend for their existence. Additional knowledge is urgently needed in order to understand the biology of the flea, especially in the subarctic and Arctic areas of the world. The data collected thus far indicate that most fleas in the taiga have one or possibly two generations a year. By late winter and early spring, Malaraeus penicilliger dissimilis (Jordan, 1938) is frequently the only species encountered upon the microtine rodents. During July, August, September and October, the small mammals are most abundant. Simultaneously, the flea infestation rates upon the mammals increase, and the number of different species encountered also becomes more varied.
The experiment described in this report was undertaken to explore practicable measures that might minimize dehydration and other metabolic derangements in a fasting, arctic survival situation. Twenty- eight men, divided into four groups, were fed a standard diet of USAF IF#10 rations in barracks for two days, then subjected to a three-day simulated survival situation, followed by two days of standard diet in barracks. Group A received no supplements, Group B received an electrolyte supplement administered as 150 mEq NaCl the first day and 150 mEq NaHCO3 the next two days, Group C 500 kcal as sucrose, and Group D 500 kcal as sucrose plus electrolyte as in B. Results suggest that a survival ration could, with benefit, comprise 500 kcal/day of carbohydrate supplemented with a sodium salt, as this combination ameliorates dehydration, hypoglycemia and ketonuria ordinarily associated with a survival situation. Provision of sodium as bicarbonate did not appear to be of any advantage.
Previous work has shown that several of the deleterious effects of a fasting, arctic survival situation can be ameliorated by provision of supplemental sodium and as little as 500 kcal/day as sucrose. The basis of current arctic survival ration is "pemmican" or a meat bar composed of powdered lean meat mixed with fat. The present experiment compares, under survival conditions, metabolic changes in men fasting completely, men receiving sucrose and electrolyte supplements, and men receiving the meat bar. Eighteen men divided into three groups of six men each, ate a standard diet of USAF IF#10 rations in barracks for two days, then underwent a seven-day simulated survival situation. Group A received no supplement; B received 500 kcal as sucrose daily, plus 150 mEq NaCl on day 1 and 150 mEq NaHCO3 on days 2 - 7; C received 500 kcal as meat bar. Mean % weight losses were: Group A, 7.64; Group B, 5.72; Group C, 6.92. Total ketone excretions were respectively 23.7, 2.7, and 11.7 gm. Sodium "balances" were, respectively -249, -388, and -240 mEq. Isocaloric intake of pemmican at this level did not appear to have any great advantage over simple starvation, whereas sucrose with a sodium salt supplement prevented or ameliorated some of the symptoms of starvation. It was concluded that although the caloric density and high protein content of pemmican are advantageous to fully-fed men, pemmican is inferior to sucrose plus sodium salts for severly limited calorie regime.
Toxicity of the tranquilizers, chlorpromazine and chlordiazepoxide, and the sedative hypnotics, morphine and promethazine, increased with acute exposure to cold. Toxicity of amphetamine, a stimulant, was lowered at reduced temperatures. In non-cold-acclimatized rats, all drugs tested except amphetamine produced some degree of depression in avoidance response rates. With addition of alcohol and cold, response rates were depressed further. Depressant effects of drugs, alcohol and cold appeared to be approximately additive, except in the case of chlordiazepoxide, which interacted with alcohol to produce a synergistic effect. Usually a decrease in response rate was accompanied by an increase in shock rate. Rats receiving alcohol alone, however, sometimes showed a simultaneous reduction in shock rate and response rate while amphetamine increased response rate and decreased shock rate. This stimulating effect was antagonized by both alcohol and cold. Cold-acclimatized animals responded as well or better in the cold than at room temperature despite the presence of drugs. Addition of alcohol to chlorpromazine or saline produced a depression commensurate with that observed in non-acclimatized rats. Alcohol enhanced the effects of amphetamine at reduced temperatures. There were only small differences among treatments with regard to shock rates in rats receiving saline or amphetamine. In rats given chlorpromazine, there was an increase in shock rates where responses decreased with addition of alcohol. Alcohol depressed habituated rats more than non-habituated rats. Habituated, acclimatized rats showed an even greater impairment in avoidance behavior at room temperature than did cold-acclimatized but non-habituated rats.
Heart rates, body temperature, and urinary output were studied in a variety of activity states in one or all of a group of four bears (two grizzly bears, Ursus horribilis, and two black bears, Ursus americanus Pallas). In addition, the cardiac activity of three black bears was studied during whole body hypothermia. The resting heart rates obtained during winter dormancy from three bears were significantly lower (75-91%) than those obtained during the summer. The physiological activity cycle of the dormant bears did not change appreciably as they continued to show a relatively high heart rate (40 beats/minute) in the morning hours. Body temperatures obtained from one black bear during winter dormancy showed only a 4° C depression. One dormant bear did not urinate for at least three months, and it was not until the third day post-arousal that voiding occurred. The three black bears subjected to whole body hypothermia experienced asystole and cardiac arrest at body temperatures of 16° - 21° C. At the time of cardiac arrest, heart rates as low as 1 beat/minute were recorded, indicating that bears could maintain low hypothermic heart rates.
Infrared thermograms were made with a scanning radiometer of 15 nude subjects exposed to environments of 4° and 23° C for two hours and sweating subjects exposed to an environment of 27° C for 10 minutes. Surface temperatures of 41 different body areas were determined by relating calculated temperature values for a gray scale on each thermogram with densitometer readings. Surface temperatures were found to be more variable in the cold, 8° to 15° C, with an average mean temperature of 11° C. The nose, pectoral area, patella, gluteus maximus and fatty tissue about the waist were cold regions whereas the upper chest, forehead and spinal column were warm regions. In a comfortable environment, the subjects' surface temperatures were less variable, 25° to 29° C. Surface temperatures of subjects in comfort environments show similar differences between identical body regions as seen in the cold, but the magnitude of the temperature gradients was less. Sweating subjects had uniform surface temperatures, mean 33° C, with only small variations. These data were used to compare various methods for determining mean skin temperatures.
Records were made of heart rates of 4 black bears, 2 males and 2 females, ages 1 to 42 months, weighing 0.6 - 70 kg. In the large bears, succinylcholine chloride was administered intramuscularly. The cubs were held while syringe needles connected to an EKG machine were inserted subcutaneously. It appears there is a marked fall in heart rate in black bears with increasing age until adulthood is reached. Succinylcholine vs. handling without anesthetic does not appear to be a factor in the results. Rates seem high, especially those of the larger, older bears. Though rectal temperature was normal, the excitement incident to anesthetic injection and the convulsive nature of its onset of action must be considered as factors in elevation of heart rate. Thus it seems possible that heart rates of the young bears are more reliable and that decrease in heart rate with age is even more marked than shown here.
