Model of human/liquid cooling garment interaction for space suit automatic thermal control.

The Wissler human thermoregulation model was augmented to incorporate simulation of a space suit thermal control system that includes interaction with a liquid cooled garment (LCG) and ventilation gas flow through the suit. The model was utilized in the design process of an automatic controller intended to maintain thermal neutrality of an exercising subject wearing a liquid cooling garment. An experimental apparatus was designed and built to test the efficacy of specific physiological state measurements to provide feedback data for input to the automatic control algorithm. Control of the coolant inlet temperature to the LCG was based on evaluation of transient physiological parameters that describe the thermal state of the subject, including metabolic rate, skin temperatures, and core temperature. Experimental evaluation of the control algorithm function was accomplished in an environmental chamber under conditions that simulated the thermal environment of a space suit and transient metabolic work loads typical of astronaut extravehicular activity (EVA). The model was also applied to analyze experiments to evaluate performance of the automatic control system in maintaining thermal comfort during extensive transient metabolic profiles for a range of environmental temperatures. Finally, the model was used to predict the efficacy of the LCG thermal controller for providing thermal comfort for a variety of regiments that may be encountered in future space missions. Simulations with the Wissler model accurately predicted the thermal interaction between the subject and LCG for a wide range of metabolic profiles and environmental conditions and matched the function of the automatic temperature controller for inlet cooling water to the LCG.

Automatic control of thermal neutrality for space suit applications using a liquid cooling garment.

BACKGROUND: Thermal control in the EVA spacesuit requires attention from the astronaut which is not always desirable or feasible. Improvements in thermal control involve implementation of an automatic thermal control system operating independently of the knowledge of the working astronaut. METHODS: A control system was designed, developed, and tested to automatically maintain a subject's thermal neutrality while wearing a liquid cooling garment (LCG). Measurement of CO2 production as an indication of metabolic rate was used as a signal to initiate the control response. Mean body temperature, computed as a function of ear canal temperature and mean skin temperature, provided feedback to account for the thermal state of subjects as they were being cooled by the LCG. The control algorithm was tested on nine subjects, six males and three females, who performed a varying 90-min metabolic profile using an arm cranking ergometer. A total of 27 tests, three for each subject, were conducted in a thermal chamber at three different environmental temperatures: 10 degrees C, 18.3 degrees C and 26.7 degrees C. RESULTS AND CONCLUSIONS: Evaluation of subjective comfort rating and quantitative energy storage indicates good performance of the controller in maintaining thermal neutrality for the subject over a wide range of environmental and transient metabolic states. Measurements of metabolic rate effectively initiated controller response, and feedback of mean body temperature to the controller proved very capable of accounting for various steady-state environmental conditions and inter-subject variability.

Exercise Medicine in Medical Education in the United States.

In brief: A review of 92 US medical school bulletins showed that only four schools (4%) offer exercise medicine as part of required undergraduate course work. In 31 schools (34%) exercise information is offered on an elective basis; 57 schools (62%) offer no formal instruction of this type. Despite both the increasing study of the health aspects of cardiorespiratory fitness and the public's growing awareness of these benefits, medical schools continue to place little emphasis on this important component of preventive medicine. The authors recommend that medical students be required to take at least a short course in exercise medicine that emphasizes cardiorespiratory fitness.

Analysis of public attitudes toward homosexual behavior.

Data from a 1974 representative survey of the white American adult population indicate that most white Americans (75%) disapprove of homosexual relations. Those persons who tend to hold more favorable attitudes toward homosexual relations are those under 30 years of age, those living in larger urban centers, and those with college experience.

Sexual aspirations and sexual behaviors among homosexually behaving males and females: the impact of the gay community.

Questionnaires were administered to 100 males and 168 females who expressed strong homoerotic aspirations. These two groups were further divided into those who were members of the gay community and those who were not. Two questions served to focus the research effort: (a) to what extent is the relationship between homoerotic sexual aspirations and subsequent gratifications different for homosexuality behaving females and males, and (b) what, if any, effect does membership in the gay community have on the sexual facilitation of these aspirations? Analysis of the data suggests that issues pertaining to differences between homosexually behaving males and females cannot be addressed apart from corresponding issues concerning the impact of the gay community as a facilitator of homoerotic sexual aspirations.