This study evaluated the effect of a macro- versus a microcooling system on the cognitive, psychomotor and physiological performance of human operators. Male subjects (n = 24) were acclimatized for four days and then subjected to three different environmental conditions: hot ambient (40°C; 40% RH), microcooling and macrocooling. Each environmental condition was repeated twice; once under a rest condition and once while simulating a physical workload of 40 W. Four performance tests (reasoning, eye-hand coordination, memory, reaction time) were conducted once every hour for four hours. Five physiological measurements, viz rectal temperature, skin temperature, heart rate, total sweat loss and sweat rate, were taken. A significant difference existed between the physiological responses under the hot ambient condition and both cooling conditions. For all five physiological parameters he human operator benefitted substantially whatever the cooling condition. The psychological performance results indicated a greater benefit under the cooling conditions, though various external factors may have influenced responses. User perception showed that macrocooling was perceived to be the optimal method of cooling. The results showed that there was no difference in the extent to which both rectal temperature and heart rate (for rest and work conditions) decreased over the 4-hour study period with micro- and macrocooling. In the baseline hot environment both increase. Sweat rate was lowest when resting or working in a microcooled environment and at its highest in the hot baseline environment. Mean skin temperature was lowest (for rest and work conditions) with microcooling and highest in the hot baseline environment. Reaction time and memory/attention were the same under all three environmental conditions. Eye-hand coordination was better with cooling than without, but did not differ between the two cooling conditions. Reasoning ability was poorest under the hot baseline condition and best in the macrocooled environment. User perception showed that the subjects found macrocooling highly acceptable. Microcooling was found to be uncomfortable, particularly because cold air (18 - 21°C) entered the jacket at one point which caused numbness of the skin at that point. Jackets did not always fit subjects well and the umbilical cord restricted free movement.

Abstract The purpose of the study was to examine the amount of cold exposure and factors affecting it at the population level in Finland, to determine what type of cold acclimatisation, if any, develops in urban residents in winter, and to find out whether cold acclimatisation or acclimation has a functional significance on psychological or physical performance. Tasks of low physical activity requiring attention and concentration (cognition, postural control) were assessed in cold. In a cross-sectional population study Finns aged from 25 to 74 years (n=6,951) were queried of their wintertime outdoor exposure duration and factors affecting it. In experimental studies seasonal cold acclimatisation (thermal responses) and its effect on cognition were assessed in the laboratory, where 15 young urban subjects were exposed to cold in winter and summer in bright or dim light. A controlled cold acclimation trial (n=10) was performed to study the effects of repeated exposures to cold on cognitive performance and postural control in young urban subjects. In the Finnish population the average amount of cold exposure in winter represents 4% of the total time. Most of the cold exposure occurs during leisure time and in outdoor occupations (agriculture, forestry, mining, industry, construction). Factors explaining increased occupational cold exposure were: occupation, age and a lesser amount of education. Factors associated with more leisure-time cold exposure were: being employed in outdoor occupations, being a pensioner, housewife, unemployed, practising physical exercise, and reporting at least average health. The experimental studies showed seasonal differences and aggravated thermal responses in urban residents in winter, but did not detect habituation responses typical of cold acclimatisation. In both seasons, acute moderate cold exposure resulted in positive, negative or mixed effects on cognition, reflected as changes in response times and accuracy. Simple cognitive tasks were impaired in cold, and in complex tasks both negative, positive and mixed effects were observed. It is suggested that cold exposure affects cognition through different mechanisms related to either distraction or arousal. Cold exposure increased postural sway by 70-90%, suggesting impaired postural control. Repeated exposures to moderate cold, reducing stress and discomfort and dampening physiological responses, did not markedly affect cognitive performance or postural control.

After an initial four week baseline period, during which headache activity and medication consumption were monitored, 28 migraineurs were randomly assigned to one of the following groups: (a) the biofeedback temperature warming group, (b) the visual imagery group, (c) the combined treatment group, or (d) the comparison group. All four groups continued to monitor their headache activity and medication consumption during the eight week treatment period and the eight week follow-up period. A two way analysis of variance computed on groups over time indicated a significant decrease in headache activity and medication consumption. During the follow-up period (a) the combined treatment group had significantly fewer headaches than the biofeedback group or the comparison group and (b) the visual imagery group and the combined treatment group had significantly fewer headache hours than the biofeedback group or the comparison group. These results do not appear to be attributable to differences between groups on the amount of time spent in home practice or subjective ratings of relaxation. There was no consistent relationship between increases in finger temperature and headache activity improvement. Decreases in powerful other scores, as measured by the Health Attribution Test, and increases in subjective ratings of internal control were consistent with a reduction in headache activity and medication consumption.

The effect of total metabolic cost expenditures on the precision of behavioral thermoregulation was investigated for the purportedly eurythermic Northern Alligator lizard (Gerrhonotus coeruleus). An operant apparatus was designed to test metabolic output at different heat reinforcement magnitudes. The mean TB reflected in each trial was positively correlated to the length of reinforcement. The shuttle rate during each trial was inversely correlated to the length of reinforcement. The standard deviation and total metabolic costs did not vary significantly between trials undertaken at the same ambient temperature. Eurythermality in G. coeruleus is caused by fluctuations in preferred body temperature and not by fluctuations around this temperature. The metabolic cost of behavioral thermoregulation did not change with corresponding changes in reinforcement magnitude. This indicates that eurythermality is the recorded effect of lizards behaviorally regulating to different TB in a stenothermic manner, rather than of random TB fluctuations in a wide range of normal activity (the classical view of eurythermality).

Within the few years following the publications of the first studies on reptilian thermoregulation (Mosauer, 1936; Attsatt, 1939; Cowles and Bogert, 1944; and Strelnidov, 1944) there has been an increasing number of investigations concerned with the mechanisms that underlie this phenomenon. Many studies have demonstrated that heliothermic lizards maintain a relatively constant body temperature during per- iods of diurnal and seasonal activity. Much of this regulation is dependent upon behavior. An extensive review of thermoregulation in both lizards and snakes has been compiled by St. Girons and St. Girona (1956).

The purpose of this investigation was to separate the effects, and determine the optimal and most feasible methods, of promoting skin temperature increase in a clinical prison population. There were no significant differences among the instructional sets with respect to skin temperature increase. Skin Temperature feedback significantly delayed the time of maximum temperature increase. However, the average delay of 3.5 minutes was not considered to be clinically significant. No other significant effects were evidenced from feedback training. It was suggested that the lack of differential effects among the instructional sets and feedback training may be a characteristic of the early stages of training and that significant differences might emerge if training were continued over a greater number of sessions.The question was raised as to whether skin-temperature training had taken place during the two training sessions. The subjects may have been displaying a nonspecific "relaxation response" or habituation to the experimental situation. It may take more than two sessions before significant conditioning of the skin-temperature response occurs. Recommendations for future research were specified, including an increase in the number of training sessions and the addition of new control procedures.

Five adult male volunteers were studied to investigate the effect of opiate receptor blockade on the physiological response to a maximum of 60 minutes of stationary cycling at 70% V02peak in a hot (33 0 C/65% RH) environment. Exercise bouts were conducted following the administration of naloxone (4mg IV) 5 minutes prior to exercise with a follow-up 4mg dose at 25 minutes of exercise. In the placebo trial, volume-matched doses of saline were administered at the same points. No significant drug effect was observed on rectal or mean skin temperature during exercise. Post-exercise skin temperature was significantly (P<.001) higher on naloxone versus saline. Forearm blood flow (FBF) was consistently higher from minute 25 of exercise until test termination, although only the minute 25 and minute 55 data points were significantly elevated (P<.05, P<.005, respectively) . The rectal temperature threshold at which FBF plateaued was higher on naloxone (P=.054), and the FBF: rectal temperature slope was higher on naloxone throughout the trial. No significant changes were observed in heart rate or estimated mean arterial pressures, although both were consistently lower on naloxone. Gross sweat response was not altered by the drug. Plasma Beta-Endorphin was significantly (P<.Ol) higher on naloxone versus saline, and Beta-Endorphin was significantly elevated in the naloxone trial only. The observation that FBF was significantly higher on naloxone without inducing compensatory heart rate or blood pressure changes suggests that the opioids may be involved in the blood volume shifts that occur during prolonged exercise in the heat. / Master of Science

Animals in the Southern African sub-region are faced with unpredictable seasonal rainfall patterns and unpredictably low resource availability due to the influence of the El Nino Southern Oscillation System. This has led to conservative energetic traits in animals that offset the costs of maintaining homeostasis in the unpredictable environments they inhabit. One of these animals is the rock hyrax (Procavia capensis). Past research has looked at the thermoregulation of rock hyrax in the laboratory. Results indicated that rock hyrax had labile body temperatures that reached lethal levels at ambient temperatures above 39°C. Laboratory studies separate endogenous thermoregulation from behavioural thermoregulation and do not reflect the overall thermoregulatory potential of the rock hyrax in maintaining body temperatures. This study looked at the thermoregulation of rock hyrax in their natural environment. Body temperatures were measured in the field using Thermochron iButtons inserted into the intraperitonial cavity of the animals. Behavioural observations were also recorded on subgroups and individually marked animals. Rock hyraxes were exposed to large fluctuations in ambient temperatures and food availability during the course of this study. In winter, ambient temperatures ranged between 5-25°C and in summer between 18-42°C. Our results show that rock hyrax seasonally and daily altered both their physiological and behavioural thermoregulation to control body temperature efficiently. The physiological alterations observed in rock hyrax differed between winter and summer. During winter, when food availability was low, rock hyrax maintained body temperatures at a lowered level relative to summer. Body temperatures fluctuated to a greater extent during winter as a result of reduced body temperatures at night and increased body temperatures due to basking during the diurnal hours. During summer, rock hyrax displayed high body temperatures, which reached hyperthermic levels. This enabled rock hyrax to forage during midday hours since heat loads could be easily dissipated through passive conduction in the cooler rock crevices. Rock hyrax employed different behavioural patterns in winter and summer. It is proposed that rock hyraxes are unable to meet energetic demands on a low quality and patchy food resource under low ambient temperatures. Predation is also a cost to foraging and becomes increasingly important when rock hyraxes have to move large distances away from crevices to find food. The most frequent behaviour recorded in rock hyrax during winter was basking. Basking enabled rock hyrax to maintain body temperatures with very little thermoregulatory cost. Differences were also recorded in behavioural patterns in rock hyrax of different sizes. Juveniles, due to their small body size and high energetic demands foraged more frequently than adult rock hyrax. During summer, rock hyrax spent considerable time in the rock crevices. This was because ambient temperatures exceeded the upper limit of the thermoneutral zone of the rock hyrax throughout most of the day. Rock hyrax therefore escaped the excessive temperatures by utilizing the cooler rock crevices, which remained at temperatures within the rock hyraxes thermoneutral zone. The most frequent behaviour recorded in rock hyrax aboveground was foraging. Since forage was abundant around the rock crevices during summer, predation risk was less of a factor influencing foraging behaviour. Since basking is an essential component of the rock hyraxes thermal biology during winter we examined basking behaviour in more detail. Basking in the morning was not used to increase body temperatures from hypothermic levels as otherwise thought. Instead, it was used to maintain body temperatures at low ambient temperatures by altering posture, orientation to the sun and basking bout lengths. During the early morning, when heating rates were greatest, rock hyrax orientated their bodies exposing the greatest surface area to solar radiation. During midday, reduced basking bout lengths and the reduction of surface areas exposed to the sun reduced the heat loads during the hottest parts of the day. Rock hyrax appeared to utilize the warm rock surfaces during the late afternoon when the sun was setting to maintain body temperatures before entering the crevices for the night. The combination of physiological and behavioural thermoregulation therefore enables rock hyrax to maintain homeostasis with very little energetic costs in an environment that displays variability in both ambient temperatures and resource availability. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2003.

Dissertation (Ph.D.)--University of South Florida, 2006. / Title from PDF of title page. Document formatted into pages; contains 107 pages. Includes vita. Includes bibliographical references.

This study compared biofeedback assisted cue-controlled skin temperature training with skin temperature biofeedback training in subjects attempting to raise the digital skin temperature of their dominant hand. In addition to classification according to training, the subjects were also divided into two diagnostic groups. One group was composed of subjects with cold hands and Raynaud's disease while the other group consisted of nonRaynaud's disease cold handed subjects. The treatment and diagnostic groups were compared along the dimensions of amount of posttreatment digital skin temperature change and degree of generalization of digital skin temperature control to a cold room challenge task.